Chemistry of the carbon compounds; or, Organic chemistry

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A TEXT- BOOK

OF

ORGANIC CHEMISTRY.

RICHTER.

STANDARD TEXT-BOOKS.

RICHTER'S INORGANIC CHEMISTRY.

A TEXT-BOOK FOR STUDENTS. By PrOF. VICTOR VON RiCHTER,

University of Breslau. Third American from Fifth German Edi-
tion. Authorized Translation. By Edgar F. Smith, m.A., PH.D.,
Prof, of Chemistry, University of Pennsylvania, Philadelphia. With
89 lUus. and a Colored Plate of Spectra. l2mo. Cloth, ;j2.oo

From Prof. B. Silliman, Yale College, New Haven, Conn. — *' It is decidedly
a good book, and in some respects the be^t manual we have."

From Prof. A, A. Bennett, Chicago University. — " I am satisfied this work
is the best that I have yet seen, and that it will in a high degree fill the want."

Front the Science Record, Boston. — " Notwithstanding the multitude of text-
books on chemistry, there is always room for a good one, and the present work
will undoubtedly fall under this head. Prof. Von Richter's work met with great
success abroad,'owing to its unusual merit. In presenting the subject to the
student, the author makes a point to bring out prominently the relations existing
between fact and theory, too commonly considered apart. * * * The rapid
sale, in Germany, of three editions of this work seems to show the common ver-
dict is greatly in favor of its inductive methods. * * * The periodic system
is so treated as to prove a really valuable aid to the student, and especially in
the relations of the metals. * * * Von Richter's text-book deserves a hearty
welcome at the hands of teachers of chemistry desirous of instructing in modern
theories and on a rational basis. This translation is neatly printed on paper of
light weight, making a very convenient handbook."

SMITH'S ELECTRO-CHEMICAL ANALYSIS.

A PRACTICAL HANDBOOK. By Edgar F. Smith, Professor of
Chemistry, University of Pennsylvania, Translator of Richter's
Chemistries, etc. 26 Illustrations. l2mo. Cloth, $1.00

*^* This handbook is designed to meet the wants of a large and
growing class of students and chemists, who are desirous of becom-
ing acquainted with this method of quantitative analysis that is daily
acquiring more importance. The author has devoted much time to
this branch of analysis and has succeeded in making a book that is
exceedingly clear, concise and practical.

SMITH & KELLER, EXPERIMENTS.

arranged for STUDENTS IN GENERAI, CHEMISTRY. By PrOF.

Edgar F. Smith, Translator of Richter's Chemistries, and Prof.
H. F. Keller, Prof, of Chemistry in Michigan Mining School,
Houghton, Mich. Second Edition, Enlarged. With many Illus-
trations. Interleaved for Notes. 8vo. Cloth, net, .60

*^* The first edition of this little Laboratory book excited much
attention as being the most practical guide for the student that has yet
appeared. This edition has been revised and considerably enlarged.

F. BLAEISTON, SON & CO., PUBLISHERS, PHILADELPHIA,

CHEMISTRY

CARBON COMPOUNDS

%

ORGANIC CHEMISTRY

PROF. VICTOR VON RICHTER,

UNIVERSITY OF BRESLAU.

AUTHORIZED TRANSLATION

BY

EDGAR F. SMITH,

PROFESSOR OF CHEMISTRY, UNIVERSITY OF PENNSYLVANIA.

SECOND AMERICAN EDITION

FROM THE

SIXTH GERMAN EDITION.

WITH ILLUSTRATIONS.

PHILADELPHIA :

P. BLAKISTON, SON & CO.,

No. I0I2 Walnut Street.
1891.

A. M-oGo^

ORi\!ELL\
UmVER£^TY

COPYRIGlfe. I§W?, W TE* ^tiKlStOI^-, JSON & CO,

Press of Wm. F. Fell & Co.,

1220-24 Sansom St.,

philadelphia.

PREFACE TO SECOND EDITION.

The present American edition of v. Richter' s Organic Chemistry
will be found to differ very considerably, in its arrangement and
size, from the first edition. The introduction contains new and
valuable additions upon analysis, the determination of molecular
weights, recent theories on chemical structure, electric conductivity,
etc. The section devoted to the carbohydrates has been entirely
rewritten, and presents the most rfecent views in regard to the con-
stitution of this interesting grbup of compounds. The sections
relating to the trimethylene, tetraraethylene and pentaraethylene
series, the furfurane, pyrrol and thiophene derivatives, have been
greatly enlarged, while the "subsequent .chapters, devoted to the dis-
cussion of the aromatic compounds, are quite exhaustive in their
treatment of special and important groups. Such eminent author-
ities, as Profs. Ostwald, von Baeyer and Emil Fischer, have kindly
supervised the author's presentation of the material drawn from
their special fields of investigation.

The characteristic features of the first edition have been retained,
so that the work will continue to be available as a text-book for
general class purposes, useful and reliable as a guide in the prepara-
tion of organic compounds, and well arranged and satisfactory as a
reference volume for the advanced student as well as for the prac-
tical chemist.

The translator would here express his sincere thanks to Prof.
V. Richter, whose hearty co-operation has made it possible for him
to issue this translation so soon after the appearance of the sixth
German edition.

PREFACE

TO THE

FIRST AMERICAN EDITION,

The favorable reception of the American translation of Prof,
von Richter's Inorganic Chemistry has led to this translation of
the "Chemistry of the Compounds of Carbon," by the same
author. In it will be found an unusually large amount of material,
necessitated by the rapid advances in this department of chemical
science. The portions of the work which suffice for an outline of
the science are presented in large type, while in the smaller print
is given equally important matter for the advanced student. Fre-
quent supplementary references are made to the various journals
containing original articles, in which details in methods and fuller
descriptions of properties, etc., may be found. The volume thus
arranged will answer not only as a text-book, and indeed as a
reference volume, but also as a guide in carrying out work in the
organic laboratory. To this end numerous methods are given for
the preparation of the most important and the most characteristic
derivatives of the different classes of bodies.

TABLE OF CONTENTS,

INTRODUCTION.

Organic Chemistry Defined, 17. Elementary Organic Analysis, 18. Determina-
tion of Nitrogen, 22. Determination of the Molecular Formula, (l) from the
Vapor Density, 29 ; (2) from the Behavior of Solutions, 33.

Chemical Structure of the Carbon Compounds, 37. Radicals and Formulas, 45.
Early Theories upon the Constitution of Carbon Compounds, 47. Stereo-
Chemical Theories, 50. Tautomerism, 54. Physical Properties, 55. Specific
Gravity, 55. Melting Points — Boiling Points, 58. Optical Properties, 60.
Electric Conductivity, 65.

SPECIAL PART.

CLASS I.— FATTY BODIES OR METHANE DERIVATIVES.

Hydrocarbons, 69.

Hydrocarbons CnH^^+j, 70. Petroleum, 71. Paraffins, 73. Unsaturated

Hydrocarbons CuHjo, 79. Hydrocarbons CnHjn_j — Acetylene Series, 86.

Halogen Derivatives of Hydrocarbons, 90.
Compounds CnH^n+i X — Alkylogens, 93. Compounds CjHjn_i X, 96.

AUyl Iodide, 98.
Compounds CnHjnX^, 99. Chloroform, 102.
Nitro-derivatives, 105.
Nitro- paraffins, 107. Nitrolic Acids, 109.
Pseudo-nitrols, 109. Nitrosates, ill. Nitroform, 112.
Alcohols, Acids and their Derivatives, 114.

Monovalent Compounds, 116.
Monovalent Alcohols, 116.

Structure of Monovalent Alcohols, 117. Formation of Alcohols, n8. Prop-
erties and transpositions, 123.
Alcohols CoHjn+i.OH. Methyl Alcohol, 124. Ethyl Alcohol, 125. Propyl

Alcohols, 127. Butyl Alcohols, 128. Arayl Alcohols, 129.
Unsaturated Alcohols, 134. AUyl Alcohol, 134. Propargyl Alcohol, 135.
Ethers, simple and mixed, 136. Ethyl Ether, 139.

vii

via TABLE OF CONTENTS.

Mercaptans and Thio-ethers, 140. Alkyl Sulphines, 144.

Esters of Minerals Acids, 146. Esters of Nitric Acid, 147. Esters of Sul-
phuric Acids, 148. Esters of Sulphurous Acid, 150. Sulpho-Acids, 152.
Sulphinic Acids, 154. Esters of the Phosphoric Acids, 155. Esters of the
Arsenic Acids, 156. Esters of Sihcic Acids, 156.

Amines, 157.

Primary, 162. Secondary, 163. Tertiary, 164. Nitroso-amines, 164. Nitro-,
amines, 164. Ammonium Bases, 165. Hydroxylamine Derivatives, 166.

Hydrazines, 166. Diazo-compounds, 167.

Phosphines or Phosphorus Bases, 168.

Arsenic Bases, 170. Cacodyl Compounds, 172.

Antimony Compounds, 174. Boron Compounds, 175. Silicon Compounds,
176.

Metallo-Organic Compounds, 177.

Compounds of the Alkali Metals, 178. Zinc Compounds, 179. Mercury
Compounds, 181. Aluminium Compounds, 182. Tin Compounds, 183.
Lead Compounds, 185. Bismuth Compounds, 185.

Aldehydes and Ketones, 186.

Aldehydes, 187. Aldoximes, 191. Aldehydes of Paraffin Series — Methyl
Aldehyde, 191. Acetaldehyde, 193. Condensation of Aldehydes, 194.
Chloral, 196. Thialdehyde, 197. Amyl Aldehydes, 198.

Unsaturated Aldehydes, 198. Acrylaldehyde, 199. Crotonaldehyde, 199.

Ketones, 200. Acetone, 203. Acetoximes, 205, Glyoximes, Z07. Conden-
sation of Acetone, 207. Phorcne, 208. Acetone Bases, 208. Acetone
Homologues, 209.

Monobasic Acids, 211.

Fatty Acids CjHjnOj, 215. Formic Acid, 216. Acetic Acid, 219. Sub-
stituted Acetic Acids, 221. Propionic Acid, 222. Butyric Acids, 226.
Valeric Acids, 228. Hexoic Acids, 229. Heptoic Acids, 230. Higher
Fatty Acids, 230. Soaps, 231. Stearic Acid, 232.

Unsaturated Acids CoHjo—^Oj, 233. Acrylic Acid, 236. Crotonic Acids, 238.
Angelic Acid, 240. Oleic Acid, 242. Linoleic Acid, 243.

Acids CjH^n— 4O2 ; Propiolic Acid, 244. Sorbic Acid, 245.
The Acid Haloids, 246. Acetyl Chloride, 247.

Cyanides of Acid Radicals, 247.

Acid Anhydrides, 248. Thio-acids and Thio-anhydrides, 250.

Esters of the Fatty Acids, 251. Spermaceti, Beeswax, 255.

Acid Amides, 255. Amide-chlorides, 258. Thio-amides, 260.

Cyan-, sulpho , and Amido- derivatives of Acids, 261.

TABLE OF CONTENTS. IX

Cyanogen Compounds, 363,

Dicyanogen, 263. Hydrocyanic Acid, 265. Halogen Compounds of Cya-
nogen, 267. Metallic Cyanides, 268. Nitroprussides, 270.

Cyanic Acids, 271. Cyanuric Acids, 272. Esters of Cyanic Acids or Cyan-
etholins, 273. Isocyanic Esters, 274. Esters of Cyanuric Acids, 275. Thio-
cyanic Acids, 277. Esters of Tiiio- and iso-thiocyanic Acids, 278. AUyl
Mustard Oil, 2S1.

Cyanides of Alcohol Radicals, Nitriles, 282.

Acetonitrile, 283. Mercury P'ulminate, 285. Fulminuric Acid, 286. Iso-
cyanides or Carbylamines, 287.

Amide Derivatives of Cyanogen, 288. Amides of Dicyanic Acids, 289.
Melamine, 290. Imido-ethers, 292. Amidines, 292. Oxamidines, 292.
Guanidines, 294.

Divalent Compounds, 296.

Divalent (diliydric) Alcohols or Glycols, 296. Methylene Derivatives, 301
Ethylene Glycol, 3ot. Ethylene Oxide, 303. Polyethylene Glycols, 304
Ethidene Compounds, 305. Propylene Glycols, 308. Butylene Glycols, 309
Amines of Divalent Radicals, 311. Imines, 312. Oxy-ethyl Bases, 314
Alkines, alkei'nes, 315. Choline, 315. Ptomaines, 316. Betaine, 31-6. Sul
phonic Acids of Divalent Radicals, 317. Isethionic Acid, 318. Taurine,
319. Ethidene Sulphonic Acids, 320.

Aldehyde Alcohols, 320. Aldol, 321. Ketone Alcohols, 321. Kelon-Alde
hydes, 323. Acetyl Aldehyde, 323. Dialdehydes, 324: — Glyoxal, 324.
Glyoxime, 324. Diketones: a- Diketones, 325. ji- Diketones, 327. y- Dike-
tones, 328. Aldehyde Acids/ 329. Glyoxylic Acid, 330. Formyl Acetic
Acid, 331.

Ketonic Acids, 331. a- Ketonic Acids, 332. Pyroracemic Acid, 332. ji- Ke-
tonic Acids, 333. Acetoacetic Ester, 338. 7- Ketonic Acids, 343. Lpevu-
linic Acid, 343.

Unsaturated Ketonic Acids, 344. Aceto acrylic Acid, 344.

Divalent Monobasic Acids, 345. a-, fS and y-oxy-acids, 348. Their Decom-
position, 350. Anhydrides of Oxy-acids, 351. Lactones, 351.
Oxy-Fatty Acids CnHjoOj, 353. GlycoUic Acid, 354. Glycolide, 356. Lactic
Acids, 356. Chloralides, 360. Hydracrylic Acid, 361. Oxybutyric Acids,
362. Butyrolactone, 362. Oxyvaleric Acids, 363.
Amides of Dihydric Acids, 363. Amido-acids, 366.

Glycocoll, 369. Alanine, 371. Leucine, 373. Diazo-acids, 373. Diazo-acetic
Acid, 374. Triazo-acids, 375. Carbonic Acid and Derivatives, 375. Cyan-
carbonic Acid, 377. Esters of Carbonic Acid, 377. Trithio-carbonic Acid,
379. Dithio-carbonic Acid, 380. Xanthic Acids, 380. Monothiocarbonic
Acids, 381. Amide Derivatives, 382. Urethanes, 382. Chlorimido-carbonic
Ethers, 384. Dithio-urethanes, 385. Thiourethanes, 385.

X TABLK OF CONTENTS.

Urea, 386. Compound Ureas, 388. Ureides, 391. Hydantoin, 391. AUo-

phanic Acid, 393. Thiourea, 394. Sulpho-hydantoin, 396.
Guanidine Derivatives, 397. Creatine, 398.

Dibasic Acids, 399. Anhydrides, 401.

Oxalic Acid, 403. Amides of Oxalic Acid, 406. Malonic Acid, 408. Succinic
Acids, 410. Succinimide, 412. Pyrotartaric Acids, 416. Adipic_Acid, 419.
Suberic Acid, 422.

Unsaturated Dibasic Acids, 423.

Fumaric and Maleic Acids, 425. Itaconic Acid, 429. Teraconic Acid, 431-
Xeronic Acid, 431.

Acetylene Dicarboxylic Acids, 431. Muconic Acid, 432. Ketone Dlcarboxylic
Acids, 432. Mesoxalic Acid, 434. Oxalo-acetic Acid, 435. Acetone Dicar-
boxylic Acid, 435. Oxal-diacetic Acid, 437. Diaceto-succinic Acid, 437.

Carbamides of Dibasic Acids, 438. Parabanic Acid, 439. Barbituric Acid,
441. Alloxan, 443. Uric Acid, 445. Guanine, 448. Caffeine, 449.

Trivalent Compounds, 450.

Trivalent Alcohols, 451. Orthoformic Ester, Ortho-acetic Ester, 452. Gly-
cerol, 452. Haloid Esters of Glycerol, 454. Glycide Compounds, 456. Alcohol

Ethers of Glycerol, 457. Acid Esters of Glycerol, 458.
Fats and Oils, 459.
Polyglycerols, 459. Butyl Glycerol, 460.

Trivalent Monabasic Acids. Glyceric Acid, 460.

Dibasic Mono-oxy-Acids. Tartronic Acid, 463. Malic Acid, 464. Amides
of Malic Acid, 465. Asparagine, 466.
Oxy-pyrotartaric Acids, 467. Paraconic Acid, 468.
Terebic Acid, 469.

Tribasic Acids. Formyl Tricarboxylic Acid, 471. Tricarballylic Acid, 472.
Aconitic Acid, 472.

Tetravalent Compounds.
Tetrahydric Alcohols, 473. Erythrol, 474.

Monobasic Acid. Erythritic Acid, 474.
Dibasic Acids. Tartaric Acid, 475. Racemic Acid, 478.

Tribasic Acids. Carboxytartronic Acid, 480. Citric Acid, 480.

Tetrabasic Acids. Acetylene Tetracarboxylic Acid, 481. Dicarbon-tetracar-
boxylic Acid, 482.

Pentavalent Compounds.
Arabite, 483. Arabinose, Xylose, Isodulcite, 483. Saccharin, 484. Aposorbic
Acid, 485. Desoxalic Acid, 485.

TABLE OF CONTENTS. xi

Hexavalent Compounds.

Manitol, 487. Dulcitol, 488. Gluconic Acid, 489, Mannonic Acid, 490.

Dloxytartaric Acid, 491. Saccharic Acid, 492. Mucic Acid, 493.
Heptavalent (Heptahydric) Compounds, 494.
Perseite, 494. Glucose •Carboxylic Acid, 495.
Butane Heptacarboxylic Acid, 496.
Manno-octite, 496.
Manno-nonite, 496.

Carbohydrates, 497. Hexoses, 497. Osazones, 501. Mannoses, 503.

Glucoses, 503. Fructoses, 505. Heptoses and Octoses, 507. Disaccharides : — •
Cane Sugar, 508. Maltose, 510. Raffinose, 511, Polysaccharides : — Starch,
512. Dextrine, 513. Cellulose, 514.

Derivatives of Closed Chains. Polymethylene Derivatives, 515. Trimethylene
Carboxylic Acid, 516,

Tetramethylene Derivatives, 519.
Tetramethylene Carboxylic Acid, 519.
Pentamethylene Derivatives, 520.
Hexamethylene, 521.
Furfurane, Thiophene and Pyrrol Derivatives.

Furfurane Group, 523.
Furfurane, 523. Furfurol, 524. Furfurane Carboxylic Acid, 526. Furfur-
acrylic Acid, 527. Methionic Acid, 528.

Thiophene Group, 528.

Thiophene, 529. Thiotolene, 531. Thioxene, 531. Thiophenin, 533. Thio-
phenaldehyde, 534. Thiophene Carboxylic Acid, 535. Dithienyl, 536. Fen-
thiophene Derivatives, 537. Methylpenthiopheae, 537.

Pyrrol Group, 538.

Pyrrol, 539. lodol, 541. Pyrrol Homologues, 542. Pyrrol Ketones, 544.
Pyrrol-Carboxylic Acid, 546. PyrocoU, 547. Pyrrol Dicarboxylic Acid, 548.
Pyrroline, Pyrrolidine, 549.

Azole Compounds or Diazoles, 551. Pyrazole, 551. Glyoxalines, 552. Tri-
azoles, 553. Thiazoles, 554. Oxazoles, 555.

CLASS II. BENZENE DERIVATIVES.

Benzene Nucleus, 556. Isomerism of Benzene Derivatives, 559. Structure of
Same, 559. Constitution of Benzene Nucleus, 563. Formation of Benzene
Derivatives, 565. Addition Products, 567.

Hydrocarbons, Cn H^n — ,, 568.

Benzene, 571. Toluene, 572. Xylenes, 573. Mesitylene, 574. Cumene,
575. Durene, 576. Cymene, 577. Hexamethyl Benzene, 579.

Xli TABLE OF CONTENTS.

Halogen Derivatives of the Hydrocarbons, 579.

Chlor-benzenes, 581. Chlortoluenes, 583. Benzyl Chloride, S84' Chlor-
ethyl Benzene, 586.

Nitro-derivatives of Hydrocarbons, 586.
Nitrobenzene, 587. Nitro-chlorbenzenes, 588. Nitro-toluenes, igo.

Nitroso-Compounds, 591.

Amido-Compounds, 591.
Aniline, 595. Substituted Anilines, 596. Nitranilines, 598. Alcoholic Ani-
lides, 599. Dimethyl Aniline, 6oi. Diphenylamine, 603. Thiodiphenyl-
amine, 604. Methylene Blue, 605. Acid Anilides, 606. Acetanilide, 607.
Anilido-acids, 608. Diphenyl Urea, 612. Phenyl Urethanes, 612. Phenyj
Mustard Oil, 614. Phenyl-thiourethane, 615. Pbenylthiurea, 616. Phenyl-
thiohydantoin, 618. Phenyl Guanidines, 619. Phenyl Amidines, 620.

Phenyl Phosphines, 621. Mercury Phenyl, 622. Toluidines, 623. Xylidines.
624. Cumidines, 624.

Diamido-Compounds, 625. Condensation Products, 627.

Diazo-Compounds, 629. Diazobenzene Nitrate, 636. Diazoimido Derivatives,

639-
Azo-Compounds, 640. Amido-azo-compounds, 641. Tropseolines, 644. Azo-

dyes, 650. Mixed Azo-compounds, 652.

Hydrazine-Compounds, 653. Phenylhydrazones, 656. Alkylhydrazines, 657.
Sulpho-Compounds, of the Hydrocarbons, 659. Benzene Sulphonic Acid, 661.
Nitrobenzene Sulphonic Acids, 664. Amidobenzene Sulphanilic Acid, 664.
Toluene Sulphonic Acids, 665.
Phenols, 666.
Monohydric Phenols, 669. Phenol, 669. Phenyl Carbonate, 670. Chlor-
phenols, 673. Nitroso-phenol, 674. Nitro-phenols, 676. Picric Acid, 677.
Amido-phenols, 679. Carbamido-phenols, 680. Amido-thiophenol, 681.
Thioanilines, 684. Phenol-sulphonic Acids, 684.
Cresols, 685. Xylenols, 687. Thymol, 687. Carvacrol, 687.

Dihydric Phenols, 689. Pyrocatechin, 689. Resorcin, 690. Hydroquininone,
•691. Orcin, 692. Creosol, 693,

Trihydric Phenols, 694. Pyrogallic Acid, 694. Phloroglucin, 695. Oxyhy-

droquinone, 696. Hexoxybenzene, 697. Quercite, Pinite, 697.
Quinones, 698.

Quinone, 699. Azophenine, 700. Chloranil, 701. Nitranilic Acid, 701. Oxy-
quinones, 702. Triquinoyl, 703. Croconic Acid, 703. Toluquinone, 704.
Thymoquinone, 705. Quinone-chlorimides, 705. Indophenols, 705. Indo-
anilines, 707. Indoamines, 708.

Alcohols, 708.
Benzyl Alcohol, 709. Benzyl hydroxylamines, 711, Tolyl Alcohols, 711.

TABLE OF CONTENTS. XUl

Divalent Alcohols, 712. Benzoyl Carbinol, 712. Phenol Alcohols, Saligenin,

713.

Phenyl Glycerol, 714.

Aldehydes, 714. Benzaldehyde, 716. Hydrobenzamide, 717. Benzaldoxime, 718.

Nitrobenzaldehydes, 719. Amidobenzaldehydes, 720. Cumic Aldehyde, 722.

Oxy-aldehydes, 723. Salicylic Aldehyde, 723. Anisic Aldehyde, 724. Pro-
tocatechuic Aldehyde, 724. Vanillin, 725. Piperonal, 726.
Ketones, 726. Acetophenone, 727. Amidoacetophenone, 728.

Keton-Aldehydes, 730. Benzoyl aldehyde, 730.

Di- Ketones : Benzoyl acetyl, 731. Benzoyl Acetone, 731.

Nitriles, 732. Benzonitrile, 733. Benzyl Cyanide, 734. Dicyanbenzenes, 735.
Benzimido-ethers, 735. Benzenylamidines, 735. Benzenyl Amidoximes, 737.
Azoximes, 737.

AROMATIC ACIDS, 737.
Monobasic Acids, 742.
Benzoic Acid, 752. Hippuric Acid, 744. Halogen Benzoic Acids, 746.

Nitro-benzoic Acids, 747. Amido-benzoic Acids, 748. Anthranilic Acid,

748. Chrysanisic Acid, 750. Azo-benzoic Acids, 750. Diazobenzoic

Acids, ^51.
Toluic Acids, 753. Phenyl-acetic Acid, 753. Lactams and Lactimes, 755.
Xylic Acids, 757. Hydrocinnamic Acid, 757. Phenylalanine, 758. Hydro-

carbostyril, 758. Cumic Acid, 760.
Ketonic Acids, 761. Phenylglyoxylic Acid, 762. Isatinic Acid, 762. Ben-
zoylacetic Acid, 763. Benzoyl Propionic Acid, 764. Di-ketonic Acids:

Benzoyl Pyroracemic Acid, 765. Quinisatinic Acid, 765.
Mono-oxy-acids, 766. Salicylic Acid, 767. Oxybenzoic Acid, 770. Paraoxy-

benzoic Acid, 770. Anisic Acid, 770.
Cresotinic Acids, 771. Phthalide, 772. Mandelic Acid, 772. Tyrosine, 775

Phen5'l-lactic Acids, 776. Oxycinnamic Acids, 777. Phenyl Glycidic Acid,

777-
Dioxy-acids, 778. Protocatechuic Acid, 779. Piperonylic Acid, 780.
Orsellic Acid, 781. Styceric Acid, 782. Trioxy-acids, 782. Gallic Acid,
782. Tannic Acids, 784. Quinic Acid, 785.

Dibasic Acids, 786.

Phthalic Acid, 786. Hydrophthalic Acids, 788. Isophthalic Acid, 788. Tere-
phthalic Acid, 789. Uvitic Acid, 790. Phenyl-succinic Acid, 791. Oxy-
di-carboxylic Acids, 792. Oxyphthalic Acid, 792. Phthalid-acetic Acid,
793. Dioxydicarboxylic Acids, 793. Hemipinic Acid, 794. Meconine, 794.
Dioxy-terephthalic Acid, 794. Succino-succinic Acid, 795. Dioxy-quinone
Dicarboxylic Acid, 796.

Tribasic Acids : Trimesic Acid, 797. Trimellitic Acid, 797.

XIV TABLE OF CONTENTS.

Tetrabasic Acids: Pyromellitic Acid, 798. Quinone Tetracarboxylic Ester

798. Mellophanic Acid, 799.
Hexabasic Acids : Mellitic Acid, 799. Euchroic Acid, 799.

Unsaturated Compounds.

Styrolene, 800. Phenyl Acetylene, 802. AUyl Phenols, 803, Safrol, Asarone,
804. Styryl Alcohol, 804. Benzylidene Acetone, 805. Cinnamic Acid,
808. Isocinnamic Acid, 812. • Atropic Acid, 813. Phenyl-propiolic Acid,
814. Coumaric Acid, 818. Coumarin, 819. Umbelliferon, 821. Piperic
Acid, 822. Benzmalonic Acid, 823. Phthalyl-acetic Acid^ 823.

Derivatives with Closed Side-Chains.

Benzofurfurane Group, 825. Coumarone, 825.
Benzothiophene Group, Benzothiophene, 826.
Benzopyrrol, or Indol Group, 826.

Indol, 827. Alkyl Indols, 828. Skatole, 830. Oxindol, 831. Indoxyl, 832.
Indogenides, 833. Dioxindol, 834. Isatin, 834. Isatoxime, 837. Indigo-
Blue, 837. Indigo-White, 840.
Benzo-diazole Compounds : Indazole, 841. Isindazole, 841.
Derivatives with Several Benzene Nuclei, 842,

(i) Derivatives of Directly Combined Nuclei. Diphenyl Group.
Diphenyl, 843. Ditolyls, 844. Benzidine, 844. Benzidine Dyes, 845.
Carbazol, 847. Coeroulignone, 848. Diphenic Acid, 849.
Diphenylene Derivatives, 850. Fluorene, 850. Diphenylene Ketone Acids,

852.
Diphenyl Benzene, Triphenyl Benzene, 852.

(2) Derivatives of Benzene Nuclei Joined by one Carbon-atom.
Diphenyl Methane Derivatives, 852.

Diphenyl Methane, 856. Benzophenone, 858. Auramine, 859. Diphenyl

Ethanes, 861. Diphenyl Acetic Acid, 861. Benzilic Acid, 862. Phenyl-

tolyl Methanes, 862. Benzoyl-benzoic Acids, 863.
Triphenyl Methane Derivatives, 864.
Triphenyl Methane, 865. Diphenyltolyl Methane, 866.
Amido-derivatives. Malachite-green, 867. Rosaniline, 871. Alkylic Ro-

sanilines, 873. Pararosaniline Derivatives, 874.
Phenol Derivatives, 876. Benzeines, 877. Rosamines, 877. Aurines, 877.

Rosolic Acid, 878.
Carboxyl Derivatives, 879. Phthalophenone, 880. Phthaleins, 88l. Fluorescein,

882. Fluorescin, 883. Coerulein, 883. Rhodamines, 884,

(3) Derivatives of Benzene Nuclei Joined by two Carbon-atoms.
Dibenzyl Group, 884.

Dibenzyl, 884. Stilbene, 885. Hydrobenzo'ins, 886. Benzoin, 887. Benzil,
888. Benzil Dioximes, 888. Pinacones and Pinacolines, 889. Carboxyl
Derivatives, 889. Tetraphenyl Ethane, 891. Dibenzyl Ketone, 891,

TABLE OF CONTENTS. XV

Anthracene Group, 892.

Anthracene, 894. Oxyanthracenes, 896. Phthalidins and Phthalidelns, 896.

Anthraquinone, 896. Oxyanthraquinones, 897. Dioxyanthraquinones : Ali-
zarin, 898. Trioxyanthraquinones : Purpurin, gcx).

Alkylic Anthracenes, 900. Methyl Anthracene, 901. Chrysophanic Acid,
901. Anthracene Carboxylic Acids, 902.
Indene and Hydrindene Group, 902. Hydrindone, 904.

(4) With Condensed Benzene Nuclei.

Naphthalene, 905. Homologous Naphthalenes, 909. Acenaphthene, 909.
Amidonaphthalenes, gio. Hydronaphthylamines, 911. Naphthylene Dia-
mines, 912. Naphthalene Red, 914. Naphthionic Acid, 915. Naphthols,
915. Naphthoquinones, 9 1 8. Naphthalene-alizarin, 919. Naphthoic Acids,
922. Naphtho-furfurane and Naphthindol, 923. Phenanthrene, 924.
Phenanthraquinone, 925. Retene, 926. Fluoranthene, 927. Pyrene, 928.
Chrysene, 928. Naphanthracene, 929.

Derivatives of Nuclei containing Nitrogen.
(i) Derivatives of five-membered Nuclei.
Phenyl-pyrazoles, 930. Fyrazolons, 933. Antipyrine, 933.
Phenol glyoxalines, 934. Phenyl-triazoles, 935.
(2) Derivatives of six-membered Nuclei.

(1) Pyridine Group, 937. Pyridine, 941. Alkyl Pyridines, 942. Oxypyri-
dines, Pyridones, 945. Lutidones, 945. Pyridine Carboxylic Acids, 946.
Pyridine Tricarboxylic Acids, 949.

Hydropyridines : Piperidine, 950.

Conine, 952. Piperideines, Tropine, 953. Nicotine, 953.

Diazines or Azines: Pyrazines, 954. Pyrimidines, 955. Pyiidazines, 957.

Oxazines and Morpholines, 957.
Pyrone Group, 958.

(2) Quinoline Group, 960. Quinoline, 965. Oxyquinolines, Kalrine, 967.
Thallin, 967. Carbostyril, 968. Alkyl Quinolines, 969. Quinaldine, 969.

Flavaniline, 971. Quinoline Carboxylic Acids, 972. Quinaldinic Acid, 972.
Quininic Acid, 973. Naphtholquinoline, 974. Phenanthridine, 974. An-
thraquinoline, 975.

Isoquinoline Group, 975.

Benzodiazines : Cinnolines, 976. Quinazolines, 977. Quinoxalines, 978.

Benzotriazines, Benzoxazines, 981.

Acridine Group, 981. Chrysaniline, 983. Phenoxazine, 983.

Phenazine Group, 984.

Eurhodines, 986. Toluylene Red, 988. Safranines, 989. Indulines, 990,
Rosindulines, 991.

XVI TABLE OF CONTENTS.

Alkaloids : 991.
Opium Bases, 992.
Cinchona Bases, 994.
Strychnine Bases, 995.
Atropine, 996. Cocaine, 996.

Terpenes, 998. Plnene, 999. Caniphenes, looi. Cilrene, looi. Cinene, 1002.
Sylvestrene, ICX33.

Camphor, 1004. Borneo-camphor, 1006. Mentha-camphor, 1006. Camphoric
acid, 1007.

Resins, 1008.
Glucosides, 1008.
Coloring Substances : Aloes, loio.
Biliary Substances, loi I. Gelatines, 1012.

Albuminates: Albumen, 1014. Fibrin, 1015. Casein, 1015. Oxyhaemoglobin
1015. Lecithin, 1016.

ERRATA.

Page 78. — 13th line from top, read hexa-hydropseudocumene for mesitylene
hexahydride.

Page 313. — 8lh line from top, read ethylene imine identical with piperazine

(P- 955)-
Page 356. — 1st line, tead. pseudo-diketothiazole.

Page 645. — 2ist line from bottom of page, read disazo-derivatives for diazo-deri-
vatives.

Page 657. — I4tli line from bottom, read a-methyl-phenyl-hydrazine, instead of
o-methylhydrazine.

Page 707. — 8th line from bottom, read

N.CeH,.N(CH3)„

^N instead

of

Page 788. — 23d line from top, read hydrogenized for hydrided.
Page 874. — 8th line from top, read iodine for iodide.
Page 912. — 5th line from top, read alicyclic for alicylic.

A TEXT-BOOK

OF

ORGANIC CHEMISTRY.

INTRODUCTION.

The chemistry of the carbon compounds was formerly called
Organic Chemistry. This designation originated in the time of
Lavoisier (i 743-1 794), who announced the fundamental ideas of
the nature of the chemical elements and compounds. He it was,
too, who first recognized the true composition of the so-called
organic substances occurring in the organism of plants and animals.
He discovered that by their combustion, carbon dioxide and water
were always formed, and showed that the component elements were
generally carbon, hydrogen, and oxygen, to which sometimes — •
especially in animal substances — nitrogen was added. Lavoisier
fur' her gave utterance to the opinion that peculiarly constituted
atomic groups, or radicals, were to be accepted as present in organic
substances ; while the mineral substances were regarded by him as
the direct combinations of single elements.

In this way it was proved that the substances peculiar to the
plant and animil kingdoms possess a composition different from
that of mineral matter. As, however, it seemed impossible, for a
long time, to prepare the former from the elements synthetically,
the opinion prevailed that there existed an essential difference
between the organic and inorganic substances ; and this led to
the distinction of the chemistry of the first as Organic Chemistry,
and that of the second as Inorganic Chemistry. The prevalent
opinion was, that the chemical elements in the living bodies were
subject to other laws than those in the so-called inanimate nature,
and that the organic substances were formed only in the organism
by the intervention of a peculiar vital force, and that they could
not possibly be prepared in an artificial way.

One fact sufficed to prove these rather restricted views to be
217 ♦

18 ORGANIC CHEMISTRY.

unfounded. The first organic substance artificially prepared was
urea (Wohler, 1828). By this synthesis chiefly, to which others
were soon added, the idea of a peculiar force necessary to the
formation of organic compounds, was contradicted. However, even
as late as 1840, Gerhardt clung to the view that chemical forces only
exercise a destroying action, and wiih Berzelius, defined organic
substances as those produced by vital force. Numerous additional
syntheses soon showed that such opinions were no longer tenable.
AH further attempts to separate organic substances from the inor-
ganic were futile. At present v,e know that these do not differ
essentially from each other; that the peculiarities of organic com-
pounds are dependent solely on the nature of their essential con-
stituent. Carbon ; and that all substances belonging to plants and
animals, can be artificially prepared from the elements.

Organic Chemistry is, therefore, the chemistry of the carbon
compounds. Its separation from general chemistry is demanded by
practical considerations; it is occasioned by the very great number
of carbon compounds.

We wruld here note the difference between the conceptions of organic and
organized \ia&\&s. Diffeient carl on compounds possess the power to assume in
the living organisms an organized structure— to foim cells. The causes and con-
ditions of this ].ower are as yet unknown to us. We l<now no more of them than
of the cause of the union of molecules to form crystals, or of the atoms to form
molecules.

Further, notice that organic chemistry does not occupy itself with the investiga-
tion of Ih^chemical processes in vegetable and animal organisms. This is the
office of Physiolcgical Chemistry.

COMPOSITION OF CARBON COMPOUNDS.

ELEMENTARY ORGANIC ANALYSIS.

Most carbon compounds occurring in vegetables and animals
consist of carbon, hydrogen, and oxygen. Many, also, contain
nitrogen, and on this account these elements are termed Organogens.
Sulphur and phosphorus are present in some naturally occurring
substances. Almost all the elements, metalloids and metals, may
be artificially introdticed as constituents of carbon compounds in
direct union with carbon. The number of known carbon com-
pounds is exceedingly great, while the possible ones are almost
without limit. The general procedure, therefore, of isolating the
several compounds of a mixture, as is done in mineral chemistry in
the separation of bases from acids, is impracticable. The mixtures
occurring in vegetable and animal bodies, are only separated by
special methods. The task of elementary organic analysis is to

DETERMINATION OF CARBON AND HYDROGEN. 19

determine, qualitatively and quantitatively, the elements of a carbon
compound after it has been obtained in a pure state and charac-
terized by definite properties. The analysis is generally limited to
the determinations of carbon, hydrogen, and nitrogen. Simple
practical methods for the direct determination of oxygen do not
exist. Its quantity is usually calculated by difference, after the
other constituents have been found.

DETERMINATION OF CARBON AND HYDROGEN.

The presence of carbon in a substance is shown by its charring
when ignited away from air. Ordinarily its quantity, as also that
of the hydrogen, is ascertained by combustion. The substance is
mixed in a glass tube with copper oxide and heated. Carbon burns
to carbon dioxide, the hydrogen to water. In quantitative analysis,
these products are collected in separate vessels, and the increase in
weight of the latter determined. Carbon and hydrogen are always
simultaneously determined in one operation. The details of the
quantitative analysis are fully described in the text-books of analytical

Fig.

chemistry. It is only necessary here, therefore, to outline the
methods employed. As a usual thing, the combustion is effected
by the aid of copper oxide in a tube of hard glass, fifty to sixty
centimetres long, and drawn into a point at one end (Fig. i).

Dry, freshly ignited, granular copper oxide is first introduced
into the tube (from a to 6) ; then the mixture of the solid substance
(about 0.2-0.3 g""-) ^•'^ pulverized cupric oxide (1$ to c), and
afterwards granular copper oxide (to d}, upon which is placed a
wad of asbestos. If the substance to be analyzed is a liquid, it is
weighed out in a glass bulb drawn out to a point, and this placed
in the combustion tube. When the latter has been filled, the
open end is closed with a cork, carrying a straight or bent calcium
chloride tube (Fig. 2).

This is filled with dried granulated chloride of calcium, which
absorbs the aqueous vapor produced in the combustion tube, while
the carbon dioxide passes on unchanged. To the calcium chlo-
ride tube is attached, by means of rubber tubing, a Liebig bulb
(Fig. 3), containing potassium hydroxide (of sp. gr. 1.27); the
potash bulb of Geissler is better. The carbon dioxide formed in

20

ORGANIC CHEMISTRY.

the combustion is absorbed in this. To the potash bulb there
is also attached a small tube ; this is filled with stick potash. It
serves to retain the slight quantity of aqueous vapor which might
escape from the bulbs. Before the combustion takes place, the
calcium chloride tube and the apparatus containing potassium
hydroxide (also the small tube) are weighed separately. Their

Fig.

Fig. 3.

connection is then made, and the combustion tube placed in
the furnace. The arrangement of the apparatus is illustrated in
(Fig. 4).

The front and back portions of the combustion tube are heated
first. These parts contain only pure cupric oxide. Subsequently
the middle portion, containing the substance, is gradually and

Fig. 4.

partially heated. The heat should be so applied that the liberated
carbon dioxide enters the potash bulbs in separate bubbles. When
this no longer occurs the combustion is complete. The flames are
then extinguished, the draw-out end of the tube is connected, by
means of rubber tubing, with a drying apparatus ; the point of the
tube is broken off and air drawn through, to remove all aqueous

DETERMINATION OF CARBON AND HYDROGEN. 21

vapor and carbon dioxide from the combustion tube, and to bring
them into their proper absorption vessels (the drying apparatus
removes moisture and carbon dioxide from the aspirated air). When
the substance is difficult to burn, it is advisable finally to conduct
a stream of oxygen through the combustion lube, in order that all
the carbon may be converted into carbon dioxide. After complet-
ing the operations just outlined, disconnect the apparatus and weigh
the various pieces separately. The increase in weight of the cal-
cium chloride tube represents the quantity of water produced ; that
of the potash bulbs, the amount of carbon dioxide. From these we
can readily calculate the quantity of carbon and hydrogen in the
substance analyzed.

Instead of mixing the substance with cupric oxide, it may be
placed in a porcelain or platinum boat, then introduced into a tube
open at both ends. The combustion in this case is carried out in
a stream of air or oxygen — method of Glaser (Fig. 5).

A layer of granular copper oxide fills the tube from rfto ^ (enclosed
by two asbestos wads). This is ignited in a current of air, then
allowed to cool. The end (/) is connected with the usual apparatus,

Fig. 5.

previously weighed ; the boat containing the substance (<:) is intro-
duced at the opposite end, and the latter joined either to an oxygen
gasometer or some apparatus for purifying gases. The layer of
cupric oxide is brought to a red heat, and the combustion executed
in a slow current of air or oxygen. To avoid a diffusion of the
gases backward in the tube, there is placed immediately behind the
boat a wad (^) of asbestos or some copper ; or a layer of mercury
is introduced between the drying apparatus and the combustion
tube. A second analysis may be commenced as soon as the first is
ended.

In this last method, platinum black (mixed with asbestos) may be substituted for
cupric oxide : — method of Kopfer. A much shorter and more simple combus-
tion furnace may then be employed. The method is adapted to the combustion
of compounds containing the halofjens (Zeitschrift fiir anal. Chemie, 1878,
17, l). Dudley has found that a platinum tube, having a layer of granular man-
ganic oxide in the anterior part, is of great service when substances are placed in
boats and exposed to combustion (Ber., 21, 3172).

When nitrogen is present in the substances burned, oxides of it are sometimes
produced, and these are absorbed in the calcium chloride tube and potash bulbs.
To avoid this source of error, the oxides must be reduced to nitrogen. This
may be accomplished by conducting the gases of the combustion over a layer of

2 2 ORGANIC CHEMISTRY.

metallic copper filings, or a copper spiral, placed in the front portion of the combus-
tion tube. The latter, in such cases, should be a little longer than usual. The
copper is previously reduced in a current of hydrogeo, then ignited, when it often
includes hydrogen, which subsequently becomes water. To remedy this, the cop-
per heated in a current of hydrogen is raised to a temperature of 200° in an air-
bath, or better, in a current of carbon dioxide or in a vacuum. Its reduction by the
vapors of formic acid or methyl alcohol is more advantageous; this may be done
by pouring a small quantity of these liquids into a dry test tube and then suspend-
ing in them the roll of copper heated to redness ; copper thus reduced is perfectly
free from hydrogen. It is generally unnecessary to use n copper spiral when the
combustions are executed in open tubes, because nitric oxide (NO) only is pro-
duced, and this passes through the caustic potash unabsorbed {Ber., 22, 3066,
Not.).

In the presence of chlorine, bromine or iodine, halogen copper compounds
(CuX) arise. These are somewhat volatile and pass over into the calcium
chloride tube. The placing of a spiral of copper or silver foil in the front part of
the tube will obviate this. When the organic compound contains sulphur a por-
tion of the latter will be converted into sulphur dioxide, during the combustion
with cupric oxide. This may be combined by introducing a layer of lead peroxide
(Zeitschrift f. anal. Chemie, 17, i). Or lead chromate may be substituted for the
cupric oxide. This would convert the sulphur into non-volatile lead sulphate. In
the combustion of organic salts of the alkalies or earths, a portion of the carbon
dioxide is retained by the base. To prevent this and to expel the COj, the sub-
stance in the boat is mixed with some potassium bichromate or chromic oxide
(Berichte, 13, 1641). When carbon alone is to be determined this can be effected,
in many instances, in the wet way, by oxidation with chromic acid and sulphuric
acid (Afessingerj £er., 21, 2910).

DETERMINATION OF NITROGEN.

In many instances, the presence of nitrogen is disclosed by the
odor of burnt feathers when heat is applied to the compounds
under examination. Many nitrogenous substances yield ammonia
when heated with alkalies (best with soda-lime). A simple and
very delicate test for the detection of nitrogen is the following :
Heat the substance under examination in a test tube with a
small piece of sodium or potassium. When the substance is ex-
plosive, add dry soda. Cyanide of potash, accompanied by slight
detonation, is the product. Treat the residue with water; to the
filtrate add ferrous sulphate, containing a ferric salt, and a few drops
of potassium hydroxide, then apply heat and add an excess of hydro-
chloric acid. An undissolved, blue-colored precipitate (Prussian
blue), or a bluish-green coloration, indicates the presence of nitro-
gen in the substance examined.

Nitrogen is determined, quantitatively, either by volume, by
burning the substance and collecting the liberated, free nitrogen, or
as ammonia, by igniting the substance with soda-lime. The first
method is applicable with all substances, while the second can only
be employed with the amide and cyanide compounds, not with those
containing the nitro- and the azo- groups.

DETERMINATION OF NITROGEN.

23

I. Method of Dumas. — In a glass tube sealed at one end
(length 70-80 cm.), place a layer (about 20 cm.) of dry, primary
sodium carbonate or magnesite, then pure cupric oxide (6 cm.),
afterwards the mixture of the substance with oxide, then a^ain pure
granular cupric oxide (20-30 cm.), and finally fill the tube with
pure copper turnings (page 22) (absut 20 cm.). In the open end of
the tube is placed a rubber cork bearing a gas-delivery tube, which
extends into a mercury bath.

The back part of the combustion tube, containing the carbonate,
is heated first ; this causes the liberated carbon dioxide to expel
the air from all parts of the apparatus. We can be certain of this
by placing a test tube filled with potassium hydroxide over the exit
tube in the mercury trough. Complete absorption of the eliminated
gas proves that air is no longer present. This done, a graduated

Fig. 6.

cylinder filled with mercury is placed over the end of the exit tube
and into the tube containing mercury is introduced, by means of
a pipette, several cubic centimetres of concentrated potassium
hydroxide. Proceed now with the combustion. First heat the
metallic copper and the layer of cupric oxide in the anterior por-
tion of the tube, and afterwards gradually approach the mixture.
When the combustion is ended, again apply heat to another part of
the sodium carbo,nate layer, to insure the removal of all the nitrogen
from the tube and its entrance into the graduated tube. The potas-
sium hydroxide absorbs all the disengaged carbon dioxide, and only
pure nitrogen remains in the graduated vessel. The latter is then
placed in a large cylinder of water, allowed to stand a short time
until the temperature is equalized, when the volume of gas is read
and the temperature of the surrounding air and the barometer

24 ORGANIC CHEMISTRY.

height noted. With these data, the weight (G) of the nitrogen
volume, in grams, may be calculated from the formula —

G = ^ ^'' - '"') X 0.0012562,

760 (I +0.00367 t)

in which V represents the observed volume in cubic centimetres,
k the barometric pressure, and w the tension of aqueous vapor at
the temperature t. The number 0.0012562 is the weight, in grams,
of I c. c. nitrogen at 0° C. and 760 mm. pressure.

Instead of reducing the observed gas volume V, from the observed baiometric
pressure and the temperature at the lime of the experiment, to the normal pressure
of 760mm. and the temperature of 0° (as recommended in the preceding formula),
the reduction may be more readily effected by comparing the observed volume of gas
or vapor with the expansion of a normal gas-volume (100) measured at 760 mm. and

o°s For this purpose employ the equation ¥„ = V , in which v represents

V

the changed normal volume (100). The apparatus recommended by Kreusler
(Ber., 17, 30) and Winkler (Ber., 18, 2534), or even the Lunge nitrometer will
answer very well for this purpose.

Tlie nitrogen determinations, as a general thing, are a little high in result, be-
cause it is almost impossible to expel the air from the combustion tube, and the
metallic copper sometimes contains H (page 22). It is, therefore, well to remove
the air from the tube by a mercury air-pump {^Zeitschrift f. analyt. Cheiiiie, 17,
409). Frarkland conducts the combustion in a vacuum, and dispenses with the
layer of metallic copper in the anterior portion of the lube. If any nitric oxide is
formed it is collected together with the nitrogen, and is subsequently removed by
absorption {Ber., 22, 3065).

Instead of collecting the disengaged nitrogen in an ordinary graduated glass
tube, peculiar " azotometers" may be employed. Of these the apparatus of Schiff
[Berichte, 13, 886), Zulkowsky {ibid., 1099), Groves [ibid., 1341), and Ilenski
{itid., 17, 1348), may be recommended. Consult the Zeitschrift fiir analyt.
Chemie, 17, 409, and Ber., 19, Ref. 710, for methods by which carbon, hydrogen,
and nitrogen are determined simultaneously.

See Gehrenbeck {Ber., 22, 1694) when a method is desired for the simultaneous
estimation of nitrogen and hydrogen in cases where the carbon was determined in
the wet way.

We can determine the nitrogen of nitro- and nitroso-compounds indirectly with
a titrated solution of stannous chloride. The latter converts the groups NO.^ and
NO into the amide group, with production of stannic chloride ; the quantity of
the latter is learned by the titration of the excess of stannous salt with an iodine
solution. Method of Limpricht {Berichte, 11, 40).

2. Method of Will and Varrentrap. — When most nitro-
genous organic compounds (nitro-derivatives excepted) are ignited
with alkalies, all the nitrogen is eliminated in the form of ammo-
nia gas. The so-called soda-lime is best adapted for this decompo-
sition ; it is prepared by adding 2 parts lime hydrate to the aqueous
solution of pure sodium hydroxide (i part), then evaporating the
mixture and gently igniting it. Mix the weighed, finely pulver-
ized substance with soda-lime (about lo parts), place the mixture

DETERMINATION OF NITROGEN. 25

in a combustion tube about 30 cm. in length, and fill in with soda-
lime. In the open end of the tube there is placed a rubber cork
bearing a bulb apparatus (Fig. 7), in which there is dilute hydro-
chloric acid. The anterior portion of the tube is first heated in the
furnace, then that containing the mixture. To carry all the am-
monia into the bulb, conduct air through the tube, after breaking
off the point. The ammonium chloride in the hydrochloric acid is
precipitated with platinic chloride, as ammonio-platinum chloride
(PtCl^. 2NH4C1), the precipitate ignited, and the residual Pt
weighed ; i atom of Pt corresponds to 2 molecules of NH3 or 2
atoms of nitrogen.

Generally, too little nitrogen is obtained by this method. A portion of the
ammonia suffers decomposition. This is avoided by adding sugar to the mixture
of substance and soda-lime, and by not heating ibe tube too intensely [Zeitschrift,
19, 91). It is also advisable to fill up the tube vfith soda-lime as far as is possible
{Zeit. fur analyt. C/iemie, 22, 280). A more rapid volumetric meihod may be
substituted for the gravimetric method in determining the ammonia. A definite

Fig. 7.

volume of acid is placed in the bulb apparatus, and its excess after combustion
ascertained by residual titration, employing fluorescein or methyl orange as in-
dicator.

The method of Will and Van entrap is made more widely applicable by adding
reducing substances to the soda-lime. Goldberg uses a mixture of soda-lime (100
parts), stannous sulphide (100 parts), and .sulphur (20 parts); this he considers
especially advantageous in estimating the nitrogen of niiro- and azo-compounds
(^Ber., 16, 2549). ,For nitrates, C. Arnold [Ber., 18, 806) employs a mixture of
soda-lime (2 parts), sodium hyposulphite (l part), and sodium formate (i part).

3. Method of Kjeldahl. — The substance is dissolved by heating it with con-
centrated sulphuric acid. Potassium permanganate (pulverized, or its solution in
sulphuric acid) is then added until a distinct green color appears. This treatment
decomposes the organic matter; its nitrogen is converted into ammonia. After
the liquid has been diluted with water the ammonia is expelled from it by boiling
with sodium hydroxide [Zeil.f. a. Chem., ■2,'2., 366). This method is well adapted
for the determination of the nitrogen of plants (compare £er.,.i8, Ref 199).

When estimating the nitrogen of nitro- and cyanogen compounds it will be
found decidedly advantageous to add sugar, and with nitrates, benzoic acid. The
addition of potassium permanganate will be unnecessary. Pyridine and quinoline
cannot be analyzed by this method [Ber., ig, Ref 367, 368).

26 ORGANIC CHEMISTRY.

DETERMINATION OF THE HALOGENS.

Substances containing chlorine and bromine yield, .when burned,
a flame having a green-tinged border. The following reaction is
exceedingly delicate. A little cupric oxide is placed on a platinum
wire, ignited in a flame until it appears colorless, when a little of
the substance under examination is put on the cupric oxide and
this heated in the non-luminous gas flame. The latter is colored
an intense greenish-blue in the presence of chlorine or bromine.
More decisive is to ignite the substance in a test tube with burnt
lime, dissolve the mass in tiitric acid, and then add silver nitrate.

The following quantitative methods for estimating halogens are
in use: —

1. A hard glass tube, closed at one end, and abaut 30 cm. in
length, is partly filled with calcium oxide, the;i the mixture of the
substance with lime, followed by a layer of calcium oxide. The
latter should be free of chlorine. Heat the tub; in a combustion
furnace; after cooling shake its contents into dilute nitric acid,
filter, add silver nitrate and weigh the precipitated silver haloid.

The decomposition is easier, if we substitute for lime a mixture of lime with )^
part sodium carbonate, or I part sodium carbonate, with 2 parts potassium nitrate,
and in the case of substances volatilizing with difficulty, a platinum or porcelain
crucible, heated over a gas lamp, may be used (/4««., 195, 295 and 190,40). With
compounds containing iodine, iodic acid is apt t ) form ; but after solution of the
mass this may be reduced liy sulphurous acid. The volu'iietric metli id of Volhard
(Ann. 190, l) for estimating ha'ogens by means of ammonium sulphocyanide may
be employed instead of the cU|Stomary gravimetric course.

The same decomposition can also be effected by ignition with ferric oxide
{Berichte, 10, 290).

2. Method of Carius. — The substance, weighed o.ut in a small
glass tube, is heated together with ^pceiitrated HNO3 and silver
nitrate to 156-300° C, in a sealed tube, "and the quantity of the
resulting silver haloid determined. The furnace of Babo {Berichte,
13, 1 2 19) is especially adapted for the heating of tubes.

In some cases the substance may also be oxidized by the method proposed by
P. Klason (p. 27).

3. In many instances, especially when the substances are soluble
in water, the halogens may be separated by the action of sodium
amalgam, and converted into salts, the quantity of which is deter-
mined in the filtered liquid.

DETERMINATION OF SULPHUR AND PHOSPHORUS.

The presence of sulphur is often shown by fusing the substance
examined with potassium hydroxide ; potassium sulphide results, and
produces a black stain of silver sulphide on a clean piece of silver.

DETERMINATION OF THE MOLECULAR FORMULA. 27

Heating the substance with metallic sodium is more accurate and
always succeeds (even when sulphur is combined with oxygen) :
the aqueous filtrate is tested for sodium sulphide with sodium
nitro-prusside.

In estimating sulphur and phosphorus ignite the weighed sub-
stance with a mixture of saltpetre and potassium carbonate ; or,
according to Carius, oxidize it by heating with nitric acid in a
sealed tube (see Ber., 20, 2928). The resulting sulphuric and
phosphoric acids are estimated by the usual methods.

Bru^elmann employs a method not only applicable in the case of sulphur and
phosphorus, but also adapted for the halogens. He burns the substances in an
open combustion tube in a current of oxygen, conducting the products through
a layer of pure granular lime (or soda-lime), which is placed in the same tube,
and raised to a red heat. Later, the lime is dissolved in nitric acid, the halogens
precipitated by silver nitrate, the sulphuric acid by barium chloride and the phos-
phoric acid (after removal of the excess of silver by HCl) by uranium acetate.
Arsenic maybe (^termined similarly {Zeits. f. anal. Chemie^ 15, I and 16, i).
Sauer recommends collecting the sulphur dioxide, arising in the combustion of the
substance, in hydrochloric acid containing bromine [Ibiti., 12, 178). To deter-
mine sulphur and the halogens by the method siiggested by P. Klason [Ber., 19,
1910), the substance is oxidized in a current of oxygen charged with nitroso-
vapors. The products of combustion are conducted over rolls of platinum foil.
Consult Th. Poleck (Zeit. f. a. Chem., 22, 17) upon a method which is applicable
for the estimation of the sulphur contained in coal gas.

Sulphur and phosphorus can often be estimated by the wet method. The oxida-
tion is effected by tneans of potassium permanganate and caustic alkali, or with
potassium bichromate and hydrochloric acid (Messinger, Ber., 21, 2914).

DETERMINATION OF THE MOLECULAR FORMULA.

The elementary analysis affords the percentage composition of
the analyzed substance. There remains, however, the " deduction
of the atomic-molecular formula.

We arrive at the simplest ratio in the number of elementary
atoms contained in a compound, by dividing the percentage
numbers by the respective atomic weights of the elements. Thus,
the analysis of lactic acid gave the following percentage com-
position ; —

Carbon 40.0 per cent.

Hydrogen 6.6 "

Oxygen 53.4 " (by difference.)

loo.o

Dividing these numbers by the corresponding weights (C =12,
H =: I, O ^ 16), the following quotients are obtained : —

40.0 6.6 , - 53.4

- — — 3-3 — = 6.6 i^ = 3.3
12 •'■' I 16 •'■'

28 ORGANIC CHEMISTRY.

Therefore, the ratio of the number of atoms of C, H and O, in
the lactic acid, is as i : 2 : i. The simplest atomic formula, then,
would be CH2O ; however, it remains undetermined what multiple
of this formula expresses the true composition. Indeed, we are
acquainted with different substances having the empirical formula
CHjO, for example oxymethylene, CHjO, acetic acid, CjHiOj, lactic
acid, CgHeOs, grape sugar, CeHijOe, etc. With compounds of com-
plicated structure, the derivation of the simplest formula is, indeed,
unreliable, because various formulas may be deduced from the
percentage numbers by giving due regard to the possible sources of
error in observation. The true molecular formula, therefore, can
only be ascertained by some other means. Three courses of pro-
cedure are open to us. First, the study of the chemical reactions,
and the derivatives of the substance under consideration ; this is
common to all cases. Second, the determination of the vapor
density of volatile substances. Third, determining certain pro-
perties of the solutions of soluble substances. *

(i) Determination of the Molecular Weight by the Chemical
Method.

This is applicable to all substances. It is generally very compli-
cated, and does not invariably lead to definite conclusions. It
consists in preparing derivatives, analyzing them and comparing
their formulas with the supposed formula of the original compound.
The problem becomes simpler when the substance is either a base
or an acid. Then it is only necessary to prepare a salt, determine
the quantity of metal combined with the acid, or of the mineral
acid in union with the base, and from this calculate the equivalent
formula. A few examples will serve to illustrate this.

Prepare the silver salt of lactic acid (the silver salts are easily
obtained pure, and generally crystallize without water) and deter-
mine the quantity of silver in it. We find 54.8 per cent. Ag. As
the atomic weight of silver = 107.7, '^^ amount of the other con-
stituent combined with one atom of Ag in silver lactate, may be
calculated from the proportion —

54.8 : (loo — S4.8) : : 107.7 = -^
X = 89.0.

Granting that lactic acid is monobasic, that in the silver salt one
atom of H is replaced by silver, it follows that the molecular weight
of the free (lactic) acid must = 89 -f- i = 9°. Consequently, the
simplest empirical formula of the acid, CHjO =30, must be tripled.
Hence, the" molecular formula of the free acid is CsHeOj = 90 :

Q =36 40.0

^6= 6 6.7

03=48 53-3

DETERMINATION OF THE MOLECULAR FORMULA. 29

When we are studying a base, the platinum double salt is usually
prepared. . The constitution of these double salts is analogous to
that of ammonio-platinum chloride — PtCl4.2(NH3HCl) — the am-
monia being replaced by the base. The quantity of Pt in the
double salt is determined by ignition, and calculating the quantity
of the constituent combined with one atom of Pt (198 parts).
From the number found, subtract six atoms of CI and two atoms of
H, then divide by two ; the result will be the equivalent or mole-
cular weight of the base.

(2) Determination of the Molecular Weight from the Vapor

Density.

This method is much simpler than the first. The results are per-
fectly reliable. It is, however, limited to only those substances
which can be gasified and volatilized without suffering decomposi-
tion. The method is based upon the law of Avogadro, according
to which equal volumes of all gases and vapors at like temperature
and like pressure, contain an equal number of molecules (see v.
Richter's Inorganic Chemistry). The molecular weights are, there-
fore, the same as the specific gravities. As the specific gravity is
compared with H ^ i, but the molecular weights with H, = 2, we
ascertain the molecular weights by multiplying the specific gravity
by two. Should the specific gravity be referred to air ^ i , then the
molecular weight is equal to the specific gravity multiplied by 28.86
(since air is 14.43 times heavier than hydrogen).

Molecular Weight. Specific Gravity.

Air — — 1443 I

Hydrogen H, = 2 i 0.0693

Oxygen O2 = 31.92 15.96 i.lo6o

Chlorine Cl^ = 70.74 35.37' 2.4550

Nitrogen N, = 28 14 0.970

Hydrogen Chloride HCl =36.37 18.18 1.260

Water H,0 = 18 '9 0.622

Ammonia NH, = 17.96 8.98 0.589

Methane CH^ ^15.97 7.98 0553

Ethane CjHg ^29.94 '4.97 1.037

Pentane QH,^ = 71.85 35,92 2.489

Ethylene QHj = 27.94 13. 97 0.964

Amylene C5H11, =; 69.85 34.92 2.430

The results arrived at by the chemical method, by transpositions,
and those obtained by the physical method, by the vapor density —
are always identical. Experience teaches this. If a deviation
should occur, it is invariably in consequence of the substance
suffering decomposition, or dissociation, in its conversion into
vapor.

3°

ORGANIC CHEMISTRY.

Fig. 8.

DETERMINATION OF THE VAPOR DENSITY.

Two essentially different principles underlie the methods employed
in determining the vapor density. According to one, by weighing
a vessel of known capacity filled with vapor, we ascertain the weight
of the latter — method of Dumas. Or, in accordance with the
other principle, a weighed quantity of substance is vaporized and
the volume of the resulting vapor determined. In this case the
vapor volume may be directly measured — methods of Gay-Lussac
and A. W. Hofmann — or it may be calculated from the equivalent
quantity of a liquid expelled by the vapor — displacement methods.
The first three methods, of which a fuller description may be found
in more extended text-books,* are seldom employed at present in

laboratories, because the recently
published method of V. Meyer,
characterized by simplicity in exe-
cution, affords sufficiently accurate
results for all ordinary purposes.
Consult £eruh/e, 15,2777,21,2018,
upon the applicability of the various
methods.

Method of Victor Meyer, —
Vapor density determination by air
displacement.^ According to this
a weighed quantity of substance is
vaporized in an enclosed space,
when it displaces an equal volume
of air, which is measured. Fig. 8
represents the apparatus constructed
for this purpose. It consists of a
narrow glass tube about 60 mm.
long, to which is fused the cylin-
drical vessel. A, of 100 c.cm. ca-
pacity. The upper, somewhat en-
larged opening, B, is closed with a
caoutchouc stopper. There is also
a short capillary gas-delivery tube,
C, intended to conduct out the dis-
placed air. It terminates m the
water bath, D. The substance is
weighed out' in a small glass tube
provided with a stopper, and va-
porized in A. The escaping air is

* Consult Handworterbuch der Chemie, Ladenburg, Bd. 3, 244.
t Ber., II, 1867 and 2253.

DETERMINATION OF THE VAPOR DENSITY. 3I

collected in the eudiometer, E. The vapor-bath, used in heating,
consists of a wide glass cylinder^ F,^ whose lower, somewhat enlarged
end, is closed and filled with a liquid of known boiling point.
The liquid employed is determined by the substance under examina-
tion ; its boiling point must be above that of the latter. Some of
the liquids in use are water (ioo°), xylene (about 140°), aniline
(184°}, ethyl benzoate (213°), amyl benzoate (261°), and dipheny-
lamine (310°).

The air-baths, suggested by Lothar Meyer {Ber., 16, logl) can be used for heating
purposes; they may be substituted for the vapor-balhs.

The method of operation is as follows : First clean and dry the
apparatus, A B, by drawing air through it by means of a long,
thin, glass tube, and, for safety, cover the bottom oi A with ignited
asbestos, or thin platinum spirals. Next place it in the heating cylin-
der, F, containing about 200 c.cm. of the heating liquid, close
B and dip the end of C into the water-bath, D. With a lamp
bring the contents of F to boiling, and wholly encircle A with
vapor, which condenses somewhat higher and flows regularly back.
The air in A is thus heated, expands, and in part escapes from the
side delivery tube through the water-bath. The non-evolution of
air bubbles indicates a constant temperature in A B, which is now
prepared to receive the substance. The cork at B is rapidly
removed, and the substance (0.05-0.1 gr.) weighed out in a small
glass vessel, permitted to drop into A, the opening is again closed,
and the end of the delivery tube, C, placed under the graduated
tube* filled with water. An improved method for the introduction
of the substance is described below. When the substance vaporizes
it displaces an equal volume of air which collects in the graduated
tube. The quantity of material taken for each determination is
always small, because it is desirable that the volume of its vapor
should not exceed Yi of the volume of A. As soon as bubbles are
no longer emitted, the determination is finished. The graduated
tube is placed to one side, the cork at B eased, to admit air and
thus avoid the entrance of water when the apparatus cools. The
volume of vapor formed is represented in the eudiometer by an
equal volume of air, reduced to the temperature of the water-bath
and given air pressure. Read off its volume and note the tempera-
ture and barometric pressure.

The calculation of the vapor density, S, from the volume of gas
found and the quantity of substance employed is simple. It equals
the weight of the vapor, P (afforded by the weight of the sub-

* See Ber., ig, 1862, for another form of vapor mantle.

32 ORGANIC CHEMISTRY.

Stance employed), divided by the weight of an equal volume of
air, F—

P

I c. cm. air at o° and 760 mm. pressure weighs 0.001293 gram.
The air volume found at the observed temperature is under the
pressure H — w, in which H indicates the barometric pressure
and w the tension of the aqueous vapor at temperature t. The

weight then would be —

, H — w*

p/ = 0.001293. *V. J ■_^ ^^^^^ / y6o ■

Consequently, the vapor density sought is —

P (i- + 0.00367 t.) 760 t_
0.001293. V. H — w

V. Meyer's method yields results that are perfectly satisfactory /?-a<rAVffl//)/, al-
though not without some slight error in principle. However, they answer, because
in deducing the molecular weight from the vapor density, relatively large numbers
are considered and the little differences discarded. A greater inaccuracy may arise
in the method in filling in the substances as described, because air is apt to enter
the vessel. L. Meyer [Ber., 13, 991), Piccard {iliid., 13, 1080), Mahlmann [ibid.,
18, 1624), and V. Meyer and Bilz (ibid., 21, 688) have suggested different devices
to avoid this source of error. To test the decomposability of the substance at the
temperature of the experiment, heat a small portion of it in a glass bulb provided
wilh a long point (see Berichte, 14, 1466)..

Substances boiling above 300° are heated in a lead-bath (jBerichte, 11, 2255).
Porcelain vessels are used when the temperature required is so high as to melt
glass, and the heating is conducted in gas-ovens [Berichte, 12, 1 1 12). Where air
affects the substances in vapor form, the apparatus is filled with pure nitrogen.
(Compare Ber., 18, 2809; 21, 688). When the substances under investigation
attack the porcelain, tubes of platinum are substituted for the latter. These are
enclosed in glazed porcelain tubes, and heated in furnaces [Ber., i'2, 2204; Zeit.
phys. Chem., i, 146; Ber., 21, 688). This form of apparatus allows of the simul-
taneous determination of temperature. The air or nitrogen which may be in them
can be displaced by carbon dioxide or hydrochloric acid gas [Ber., 15, 141. Zeit.
phys. Chem., i, 153).

For modifications in methods of determining the density of gases, consult V.
Meyer, Berichte, 15, 137, 1161 and 771 ; Langer and V. Meyer, Pyrotechnische
Untersuchungen, 1885 ; Crafts, Berichte, 13, 851, 14, 356, and 16, 457. Forair-
baths and regulators, see L. Meyer, Berichte, 16, 1087 ; 17, 478; 18, 2838.

Modifications of the displacement method, adapted for work under reduced
pressure, have been proposed by La Coste [Ber., 18, 2122), Schall [Ber., 20, 1827
and 2127; 21, 100), Malfatti [Zeit. phys. Chem, i, 159), and Eyckmann [Ber.,
22, 2754). For the method of Nilson and Petterson, see Ber., 17, 987 and ig,
Ref. 88; a\s,o Jour. pr. Chem., 33, I. See Ber., 21, 2767, for the method of Bilz.

* It is simpler to make the reduction to 760 mm. and 0° by comparison with a
normal volume (p. 24).

f The calculation of the molecular weight can be made directly and more
readily by using the equation given on p. 34.

DETERMINATION OF MOLECULAR WEIGHT. .33

(3) Determination of the Molecular Weight of Substances when in

Solution.

I. By means of Osmotic Pressure. — Recently Van't Hoff
has developed an exceedingly important theory in regard to solu-
tions. * According to this new idea chemical substances, when in
dilute solution, exhibit a deportment similar to that observed when
in a gaseous or vapor-form ; therefore, the laws applicable to gases
(Boyle, Gay-Lussac and Avogadro) possess the same value for solu-
tions. We know that the gas-particles exert pressure, and it is also
true that the particles of compounds, when dissolved, exert a pres-
sure, which is directly expressed or shown by the osmotic phe-
nomena, and hence it is termed osmotic pressure. This pressure is
equal to that which would be exerted by an equal amount of the
substance, if it were converted into gas, and occupied the same
volume, at the same temperature, as the solution. Solutions con-
taining molecular quantities of different substances exert the same
osmotic pressure. It is, therefore, possible, as in the case of gas-
pressure, to directly deduce the molecular weight of the substances
in solution from this osmotic pressure. The methods thus far
employed for the determination of this pressure have been too
complicated and time-consuming to permit of their application in
practical work. The determination of the vapor pressure, or the
freezing point of solutions is more suitable ; these are intimately
related to osmotic pressure (p. 35).

Pfeffer determines osmotic pressure by means of ailiHcial cells, having semi-
permeable walls. These are produced by saturating porous earthenware cells with
solutions of copper sulphate, and potassium ferrocyanide. A sheet of cnpper
ferrocyanide is formed in the wall of the cell, through which water can circulate,
but not sugar or other substances which may be held in solution. The pressure
exerted on the membranous cell, by the dissolved substances, is measured by the
osmotic elevation, or by a manometer. If suitably modified this method promises
to be of wide applicability (Ladenburg, Ber., 22, 1225).

The plasmolytic method of de Vries [Zeit. phys. Ckem., 2, 415), employed in
determining osmotic pressure, is based upon the use of living plant cells ; the proto-
plasraa of the latter is clothed with a thin pellicle (the protoblast), which is semi-
permeable (see above). When such cells are introduced into aqueous solutions of
definite concentration their membranes contract, if the external osmotic pressure
exceeds that of the cell-contents [Zeit. phys. Chem., 2, 415).

To calculate the molecular weight, make use of the general formula for gases:
pv = RT, in which R represent a constant, and T the absolute temperature,
caculated from — 273° forward.

If this equation is also to include the law of Avogadro (that the molecular
weights of gases or dissolved substances occupy the same volume at like tempera-
ture and pressure), then molecular quantities of the substances must always be

* Van't Hoff, Zeit. phys. Chem., i, 481 ; 3, 198. " Ein elementare Darstellung
der Theorie der Losungen," see Ostwald's " Grundriss der allgemeinen Chemie,"
i88q.

34- ORGANIC CHEMISTRY.

taken into consideration. The constant equals 84506 for gram molecular weights
(2 grams hydrogen, or 31.92 grams oxygen) at ihe temperature 0° (or 273°), and
the pressure (gas or osmotic pressure) of 76 cm. of mercury.

p . V = 84500 . T*.

V represents the volume corresponding to the gram molecular weight

M
(v = , in which a is the weight in grams of I c.cm. of the gas, or dissolved

a
stibstance, contained in i c.cm. of the solution). Substituting figures the formula

would read : p . 13.59 X = 84500 (273 + t), with the four variables p, M,

a
a and t. • If three of these be given the fourth can be calculated. Consequently, the
molecular weight .^is found from the formula : —

M

_ a . 84500 (273 + t) _ a. 6218 (273 + t)

P- I3S9 P

2. From the Lomrering of the Vapor Pressure. — The lowering of the
vapor pressure of solutions is closely allied to osmotic pressure. It is a known
fact that solutions at the same temperature have a lower vapor pressure (f) than
the pure solvent (f), and consequently boil at a more elevated temperature than
the latter. The lowering in pressure (f — i') is in proportion to the quantity
of the substance dissolved (WUilner). This harmonizes with the equation

f f/

= k. g, in which k represents the " relative lowering of the vapor pressure "

I \ for I per cent, so'utions, and g their percentage content.

If the lowering be referred not to equal quantities, but rather to molecular
quantities of the substances dissolved, it will be discovered that equi-molecular
solutions (those containing molecular quantities of the different substances in equal
amounts in the same solvent) show equal lowering — the molecular vapor pressure
lowering is constant : —

M. f-n£'=c.
f

Again, on comparing the relative lowering of vapor pressure in different solvents,
it will be found also that they are equal, if equal amounts of the substances are
dissolved in molecular quantities of the solvent. In its broadest sense the law
would read : The lowering of vapor-pressure is to the vapor-pressure of the solvent
(f) as the number of molecules of the dissolved body (n) is to the total number of
molecules (n -|- N) : —

f — f^ __ n
f n + N'

Substituting the quotients -5_ and (g and G represent the weight quanti-

m M

ties of the substance and the solvent ; m and M are their molecular weights), for
n and N, it will be easy to calculate the molecular weights.

F. M. Raoult (1887) developed these rules empirically. Soon thereafter van't

* R = ^^ ; p = 1033 = 76 X 13-59 (sp- gr- of mercury) ; v = 22330 =

, , 1033 X 22320

3 1. 92/0.001430 (wt. of I c.cm. of oxygen). R = —

273

DETERMINATION OF MOLECULAR WEIGHT. 35

Hoff {Zeii. phys. Chem., 3, 115), deduced them theoretically from the osmotic
pressure. They are only of value for non-volatile (as compared with the solvent)
substances, or such as volatilize with difficulty. The same abnormalities observed
with osmotic pressure and depression in the freezing point also appear here.

The methods for the determination of vapor-pressure are yet too little known
and primitive in their nature to be applied in the practical determination of mo-
lecular weights {Ber., 22, 1084). It is easier to determine the rise in the boiling
points; this is also more reliable (Beckmann, Zeit. phys. Chem., 4, 5).

3. From the Depression of the Freezing' Point. — The

molecular weights of dissolved substances are more accurately and
readily deduced from the depression of the freezing points of their
solutions. Blagden in 1788, and Riidorff in 1861, found that the
depression of the freezing points of crystallizable solvents, or sub-
stances (as water, benzene and glacial acetic acid) is proportional
to the quantity of substance dissolved by them. The later re-
searches of Coppet (187 1), and especially those of Raoult (1882),
have established the fact that when molecular quantities of different
substances are dissolved in the same amount of a solvent they show
the same depression in their freezing points (Law of Raoult). If t
represents the depression produced by/ grams of substance in 100

grams of the solvent, the co efficient of depression — will be the

depression for i gram of substance in 100 grams of the solution.*

The molecular depression is the product obtained by multiplying
the depression co-efficient and the molecular weight of the dissolved
substances. This is a constant for all substances having the same
solvent : —

M . 1 = C.
P

Raoult's experiments show the constant to have the following
values: for benzene 4.9; for glacial acetic acid 39; for water 19.
When the constant is'known the molecular weight is calculated as
follows: —

M = C P-.
t

A comparison of the constants found for different solvents will disclose the fact
that they bear the same ratio to each other as the molecular weights — that conse-
quently the quotient obtained from the molecular depressions and molecular weights
is a constant value (about 0.62). It means, expressed differently, that the molecule
of any one substance dissolved in 100 molecules of a liquid lowers the point of
s jIidihca(ion very nearly 0.62.

Guldberg (1870) and van't Hoff (1886), have since made a theoretical deduc-
tion of these laws from the lowering of the vapor pressure, and from the osmotic

* Ranult {Zeit. phys. Chem., 2, 353). Arrhenius expresses the content of solu-
tions by the weight in grams of the substances contained in lOO c.c. of the solution.

36

ORGANIC CHEMISTRY.

pressure. The constant C is obtained, for the various solvents, from the formula

'f 2

o, 02 TTjrp. Here T indicates the temperature of solidification of the solvent calcu-
lated from the absolute zero-point forward. W is its latent heat of fusion. In this
viray van't Hoff calculated the constants for lienzene (53), acetic acid (38.8), and
water 18.9 (see above).

The laws just described possess a direct value for indifferent sub-
stances, having but slight chemical activity. Salts, strong acids and
bases (all electrolytes) constitute the exceptions. The depressions
in freezing point are greater for these than their calculated values
(they also have greater osmotic pressure, and greater lowering of the
vapor pressure). The electrolytic dissociation theory of Arrhenius *
would account for this by the assumption that the electrolytes have
separated into their free ions. However even the indifferent bodies
exhibit many abnormalities — generally the very opposite of the
ordinary. These. seem to be due to the fact
Fig- 9- that the substances held in solution had not

completely broken up into their individual
molecules. The most accurate results are ob-
tained by operating with very dilute solutions,
and by employing glacial acetic acid as solvent.
This dissociates solids most readily.

DETERMINATION OF THE DEPRESSION OF THE
FREEZING POINT.

A weighed quantity of the solvent, is placed in a wide
test-lube of hard glass, and its freezing point deteVmined.
In the mouth of the tube is a large cork through which a
thermometer and a stirring rod pass. A wtighed quantity
of substance is now added to the solvent, and dissolved
in it. The freezing point is again determined (HoUe-
mann, Ber.^ 21, 860).

Various forms of apparatus suitable for the above pur-
pose, and methods ol working have been proposed by
Auwers, f Hentschel, J Beckmann, \ Eykmann, || and
Klobukow. If

Beckmann's Method.— A hard gla=s tube A, 2-3
cm., in widlh, with a side projection E (Fig. 9', is filled
with 15-20 grams of the solvent (weighed out accurately
in centigrams), and closed with a cork, in which rie
placed an accurate tliermometer (Walferdin), and a stout
platinum wire serving as a stirring rod. The lower part
of the tube is attached by means of a cork to a somewhat
larger, wider tube. The latter serves as an air-jacket.
The entire apparatus projects into a beaker glass filled with a freezing mixture.

* Zeit.phys. C/ieiii., I, 631 ; I, 577 ; 2, 491.
■\ Ber„ 21, 711 ; % Zeit. phvs. Cheni., 2, 307;
T[ Ibid., 4, 66.

? //w/.,2, 638; 112,966;

CHEMICAL STRUCTURE OF CARBON COMPOUNDS. 37

Cold water will answer for glacial acetic acid (congealing at 16°), and ice-water
for benzene (aliout 5°). Fiist determine the congealing point of the solvent by
cooling it 1-2° below its freezing point, and then by agitation with the platinum
lod (after addition of platinum clippings), induce ihe formation of crystals.
During this operation the thermometer rises, and when the mercury is stationary
it indicates the freezing point of the solvent. Allow the mass to melt, and intro-
duce an accurately wtit;hed amount of substance through E. When this has
dissolved the freezing point is re-determined as before.

Eykmann t^Zeit. phys. Ckem., 2, 966) has designed a method by which it is
possible to use smaller amounts of solution (6-8 grams) and substance. This is done
by using phenol (m. p. about 38°), as the solvent. Its molecular depression has
been theoretically deduced; it is about 76 (see above).

Paterno's investigations show, contrary to earlier observations, that the carbon
derivatives mostly yield normal results j the exceptions being the alcohols, phenols,
acids and oximes.*

Naphthalene may aUo be used for determinations of this kind. Van't Hoff gives
its depression constant as equal to about 70 [Ber., 22, 2501 ; and Eykmann, £er.,
23, Ref. I).

CHEMICAL STRUCTURE OF THE CARBON COMPOUNDS.

The molecular weight of a given substance and the absolute
number of atoms contained in the latter, are ascertained by elemen-
tary analysis, and the study of the chemical transpositions, or by the
determination of the vapor density. The problem of establishing
the chemical formula of a compound would soon be solved, did
not experience show that very often entirely different substances
are possessed of the same molecular composition. Isomerides
(from la()[i€piji;, consisting of equal parts), is the name given these.
In a more extended sense, isomerism includes all bodies of like per-
centage composition. When the isomerism depends upon a differ-
ence in molecular weight (p. 28), it is itrmtd polymerism ; a special
case of the latter is the allotropy of the elements (see Richter's
Inorganic Chemistry).

Real isomerism, i. e., the phenomenon of bodies of like compo-
sition and like number of atoms, being different, is interpreted only
by granting a different grouping or arrangement of the atoms in
the molecule. That this, indeed, occurs, follows from the investi-
gation of chemical reactions, as it is easy to split off from isomeric
bodies entirely different atomic groups and atoms, or even to
replace them by others. Hence, the atoms in such compounds are
differently 'distributed or linked to one another. To investigate
this different chemical union of the atoms, the chemical constitution
of compounds — as an expression for their entire chemical deport-
ment— is the task presented us. Since, however, the nature of
chemical affinity and the manner of the union of atoms to mole-

* Ber., 22, 1431, and Zei/.phys. Chem., 5, 94.

38 ORGANIC CHEMISTRY.

cules are absolutely unknown to us, the expression of chemical
constitution can only be hypothetical — a mere formulation of the
actually known regularities in the chemical transpositions of
compounds.

The various attempts to formulate the chemical constitution
of compounds belong to the history of chemistry (p. 47). At
present, the problem, especially in its relation to the derivatives of
carbon, is largely solved by the doctrine or theory of chemical
structure. This is based upon the ideas of differences in valence
in the elementary atom^, and upon their capability of combining by
single affinity units (see Richter's Inorganic Chemistry).

Although the number of cases of isomerism is but limited in
inorganic chemistry, and there being consequently but little import-
ance attached to the presentation of structural formulas, the phe-
nomena of this kind are exceedingly abundant with the carbon
compounds, so that constitutional or structural formulas, represent-
ing the entire chemical deportment, are absolutely necessary.
Frequently, very complicated relations occur, yet the structure of
all investigated carbon derivatives may be deduced from the
following principles: —

1. The carbon atoms, in their hydrogen combinations, are
constantly quadrivalent. The position of carbon in the periodic
system gives expression to this fact. The only derivative in which
carbon apparently figures as a bivalent element is carbon monoxide,
CO (see below).

2. The four affinity units of carbon are, as generally represented,
equal and similar, i. e., no differences can be discovered in them
when thsy form compounds. If these four affinities be attached to

, different elements or groups, the order of their combination is
entirely immaterial. The compounds —

CHsCl CHj-NEr^ CH,.COOII CH,CH,

Melhyl Methyl Acetic Di-niethyi.

Chloride. Amine. Acid.

CH,CI, C0(CH3^ CO/g:CH^^ CH,Ch/0;C»H.,0

Methyl Methyl- Methyl- Ethylidene

Bichloride. ethyl Acetone. ethyl Carbonate. Aceto-propionate.

are known in but one modification each ; their isomerides have
never been prepared.

3. The carbon atoms can unite in a chain-like series, by com-
bining with each other by one or more units. This they can do,
also, with other elementary atorn.s.

These principles express the relations really known at present All investi-
gated compounds prove carbon to be quadrivalent. Carbon monoxide, CO, is not
a contradiction, as valence is a relative fimction of the atoms (compare Richter's
Inorganic Chemistry), and its existence is affected in the same way by the nature

CHEMICAL STRUCTURE OF CARBON COMPOUNDS. 39

of oxygen, as by carbon; we can, with equal correctness, represent O in CO as
quadrivalent and C as bivalent. Bec.iuse CO does exist, if. in no mmner follows
that carbon can figure as a dvad in the hydrogen derivatives. Repeated efforts
to prepare compounds containing bivalent carbon were unsuccessful ^page 42).

The equi-valence of the four cvrbon affinities, in the sense above illustrated,
has likewise been positively confirmed. By the early type or substitution theory,
it appeared possible that compounds like

CH3CI and CCIH3 or CH3NHJ and NH^CH,, etc.,

were isomeric. All experiments instituted proved that the succession of substitu-
tion or the replacement of the substituting atoms again were without effect;
identical bodies resulted in all analogous cases.

It may be added, in regard to the capability of union of the carbon atoms with
each other and with other elements, that all the imaginable combinations are
really not possible. Certain groupings can in no way be realized, and the union
of two atoms is very often influenced by the atoms present with them in the mole-
cule. The related phenomena, which are of such great interest as regards the
constitution, will be developed later, in special cases.

The different manner, in the linking of the carbon atoms, shows

itself most plainly in their hydrogen compounds — in the so-called

hydrocarbons. By removing one atom of hydrogen from the

simplest hydrocarbon, methane, CH,, the remaining univalent

group, CH3, can combine with another, yielding CH3 — CH3, or

CgHe, ethane or dimethyl. Here, again, a hydrogen atom may

be replaced by the group CH,, resulting in the compound CH3 —

CH2 — CH3 propane. The structure of these derivatives may be

more clearly represented graphically: —

H H H H H H

I II III

H— C— H H— C— C— *t. H— C— C— C— H etc.

I II III

H H H H H H

CH4 CjHg Cjltj

By continuing this chain-like union of the carbon atoms, there
arises "an entire series of hydrocarbons: —
CH3 — CH, — CH, — CH3 CH3 — CHj — CH, — CHj — CH,, etc.

having the common formula C„ Hj^^j, in which each member
differs from the one immediately preceding and the one following,
byCH,.

The compounds constituting such a series are said to be homolo-
gous. In addition to the hydrocarbons forming such a series, many
others exist, e. g., the monohydric alcohols and monobasic acids : —

CH,

CH,0

CVifl,

C^H,

qH,0

C,H,0,

CjHg

QHjO

QHeO^

^i^^lO

QHjoO

c^n.o.

c:h;:

c:h;:o

C^H^A

4° ORGANIC CHEMISTRY.

The compounds belonging to such an homologous series, because
of their similarity in chemical structure, exhibit great analogy in
their entire chemical character.

The manner. of union just considered, that of a simple, open
chain, is designated normal structure. In this we distinguish inter-
mediate and terminal carbon atoms; the first are connected with
two other carbon atoms and have two valence units which may be
saturated by two hydrogen atoms (or other elements). The ter-
minal carbon atoms of the chain are combined with three hydro-
gen atoms. Usually, the normal structure may be expressed by the
following formulas : —

CH3 - {CH3)n - CH3 or (CH,)„/^g»

Carbon atoms can unite with even three or four other carbon
atoms, then tertiary or quaternary union or structure arises :

CH. CH,

I I

H — C — CHg H — C — CH2 — CHg

I I

Tertiary Tertiary

'Eutane. Fentane.

CHg ^ ,S

I I

H,C— C— CH„— CH,

CHg CHg

Quaternary Quaternary

Pentane. Hexane.

This varying union of the carbon atoms explains the numberless
isomerides possible for the higher series. This will be especially
observed in case of the hydrocarbons.

In all the structural cases introduced here, the two carbon
atoms are in simple combination with each other. The number
of valence units (hydrogen atoms) with which the carbon nuclei
consisting of n atoms can directly combine equals an + 2 (p. 39).
This cannot be exceeded without the consequent destruction of the
carbon nucleus. Therefore, compounds constituted according to
the general formula CcXj^^j (in which X represents the valences
directly joined to C), are termed ja/^ra/^^/ compounds or paraffins.

Besides the hydrocarbons CnH.^„ + 2, there exists another homolo-
gous series (p. 39) of the form C^Hjo: —

C^H^ Ethylene.
C3H5 Propylene,
i CjHj Butylene.

CHEMICAL STRUCTURE OF CARBON COMPOUNDS. 41

Their existence is accounted for by assuming that in them two
carbon atoms are united by two valences — a double or bivalent
union. The following structural formulas indicate this : —

Ethylene. Propylene.

For the formula CiHg, three structures are possible : —

CH3 — CHj — CH = CHj CHj— CH = CH — CHj

and CHgN^y-i prr

As only a simple union is required for the linking of the carbon
atoms, such compounds as the last are yet capable of saturating two
valence units j they are, therefore termed unsaturated compounds.
By the addition of two hydrogen atoms, they pass into Q-J^^^j^^.
The double changes to single union : —

CH2 CHj

II + H, = I .

CHj CHj

The acceptance of this double union of the carbon atoms in no manner indi-
cates (as sometimes erroneously supposed) a close, stronger combination. It
has long been known, that the unsaturated compounds could be much more
readily broken up than the saturated ; and that they p assess, too, a greater spe-
cific volume ; hence, the double union is less intimate than the simple. (Com-
pare 1st Ed. of this book, p. 40.) The use of the double lines represents the
fact that only two directly combined carbon atoms are capable of saturation

(P- 39)-

That the unsaturated compounds do possess a greater heat of combustion is an
argument in favor of the view that the union of the carbon atoms is less intimate.
A. Baeyer [Ber., 18, 2277) has published an experimental proof of this deportment.

A third series of hydrocarbons arises when a triple union of two
carbon atoms occurs. Their composition corresponds to the com-
mon formula C„H2n_2: —

CjHj Acetylene.

C3H4 AUylene.

CjHj Crotonylene, etc.

Their structural formulas are —

CH = CH CHj — C = CH CH3 — CHj — C = CH.

We can view these as unsaturated hydrocarbons of the second
degree. They are capable of combining directly with two and
four valences, passing into the compounds C„H2„ or C^Hjo ^ j.

Compounds containing a like number of carbon atoms, with a
gradually decreasing number of hydrogen atoms, are designated
isologous compounds. The following are examples : —

CjHj

Ethane.

C3H8

Propane.

C3H3O

Propyl alcohol.

c^h'

Ethylene.

C3H,

Propylene.

CjHeO

AUyl alcohol.

C^H,

Acetylene.

C3H,

AUylene.

CjH.O

Propargylic alcohol.

42 ORGANIC CHEMISTRY.

Finally, theie is a large series of carbon compounds bearing the
name aromatic. They all originate from a nucleus composed of
six carbon atoms. Benzene, QHn, represents their simplest com-
bination. The simplest structure of this nucleus is probably one
in which the six carbon atoms form a closed ring, with alternating
single and double union, as represented by the following : —

CH = CH

/ \
HC = CH — CH = CH — CH = CH or CH CH

w /

CH — CH

j

The innumerable aromatic or benzene compounds resulting from
the replacement of H in benzene by other atoms or groups, consti-
tute a distinct class.

The ring-shaped compounds trimethylene, CsHs, tetramethylene,
CjHs, and pentamethylene, C5H0, recently described, are forerun-
ners of the stable, closed benzene ring : —

/CH,

CHj-CH,

/CH,-CH,

CH, 1

1 1

CH, 1

\CH,

CH, — CH,

\CHj — CH,

Trimethylene.

Tetramethylene.

Pentamethylene.

A series of compounds is likewise derived by the replacement of
hydrogen in the preceding hydrocarbons.

Formerly, another view prevailed relative to the ursaluraled carbon com-
pounds. It was assumed that bivalent carbon atoms could occur in the hydrogen
compounds, just as well as in carbon monoxide. The other two affinities re-
mained unsaturated or free. This view would allow the existence of innumerable

isomeric derivatives. Thus two bodies, CH2 = CH, and CHj — CH, could corres-
pond to the formula CjHj, but only the first, ethylene, really exists. In addition

to the true propylene, CH3 — CH^CH,, two other bodies, CHg — CH, — CH

1/

and CHj — C — CHj, could correspond to the formula CjHj. The preparation of
such isomerides has been fruitless. The compound CH„ methylene (see this),
cannot be made. In the case of all sufficiently well-studied unsaturated compounds,
it is established that the two free valences imariably belong to two different car-
bon atoms. By adding two atoms of chlorine to ethylene, CH, = CH„ there

arises the compound CHjCl — CHjCl ; the isomeride CH3CH, should yield CH,

— CHCl,. Inversely, we get ethylene, CH,= CH„ from its chloride, CHjCl

— CHjCl, while the isomeric, so-called ethylidene, CH3CH, cannot be obtained
from ethylidene chloride, CHg — CHCI,. If really, as above supposed, the free
affinities of the two carbon atoms are combined with each other — if double union
occur — it cannot be asserted with certainly, and it is entirely irrelevant, as we
possess no representation as to the nature of the union. It is doubtless certain that

CHEMICAL STRUCTURE OF CARBON COMPOUNDS. 43

the possibility of the so- called free valence of a carbon atom is influenced by the free
valence of another atom, vphich is in direct union with the first. It is very likely there

11 //

exists CH3 — CHj — CHj (propylene), but not the forms CH, — CHj — CH or
CH3 — C — CH3. This knowledge accords with the actual facts, and considerably
limits the number of possible isomerides. It finds expression in the supposition of
the constant tetra valence of carbon. If new isomerides are discovered in the future,
the assumption of the divalence of carbon can be admitted. So long, however, as
convincing reasons are not present, we must refrain from introducing a new, funda-
mental, and far-reaching hypothesis, which would remove the existing regularities.

In the preceding pages we have discussed the different ways in
which the carbon atoms are bound to each other in their hydrogen
derivatives. We meet these in all other carbon compounds that
may be regarded as derivatives of the hydrocarbons, resulting from
the replacement of hydrogen by other elements or groups.

Since all the facts go to prove that the four valences of the car-
bon atom are similar (p. 38), isomerisms in similar carbon nuclei can
take place only when the entering elements or groups attach them-
selves to carbon atoms with different functions; or, as ordinarily
expressed, when they occupy different chemical positions. The fol-
lowing examples serve to illustrate: —

According to the formula C2H5CI, there can be but one body
of the structure CH3 — CHjCl, because, in the original substance
CHj — CHs, dimethyl, both carbon atoms act alike. On the other
hand, two isomeric bodies of the structure —

CH3 — CHj; — CHjCl and CH3 — CHCl — CH3,

correspond to the formula CsHyCl, because, in propane, CH3 —
CH2 — CH3, from which they originate, the carbon atoms are not
similarly united, consequently, the entering halogen atoms can
occupy relatively different positions. Thus, too, four isomerides
correspond to the formula C4H9CI, two springing from normal
butane, CH3 — CHj — CHj — CH3, and two from isobutane —

^"aXfH CH etc

The number of isomerides is further increased by the entrance of
two or several similar or dissimilar atoms or groups. For the
formula C2H4C12 we have two isomerides : — CHjCl — CHjCl and
CHs — CHCI2.

For the formula CaHeClj four structural cases are possible : —

CH, CH, CH3 CHjCl

I I I I

CHj CCI2 CHCl CH,

CHCI2 CHj CHjCl CHjCI.

44 ORGANIC CHEMISTRY.

All Other possible isomerides are derived in the same manner.
The nature of the atoms or groups entering is immaterial as far as
the isomeric relations (p. 38) are concerned.

Compounds obtained from the hydrogen derivatives by the re-
placement of hydrogen by halogens or the nitro group, NO2, are
usually designated substitution products ; generally they retain the
chemical character of the parent substance. In a broader sense,
one can consider all carbon compounds as substitution derivatives
of the hydrocarbons, or of methane, CH4.

Two bivalent elements like S and O can unite with C with either
one or two valences. In the first case, they may be combined with
one or two carbon atoms : —

CH3 — CH = O CH^X CH3 — O — CH3

Aldehyde I O Methyl Oxide, or

Ethylidene Oxide. (jjj y Dimethyl Ether.

Ethylene
Oxide.

If the bivalent element unite with but one affinity to carbon, the
other must be saturated by some other element : —

CH3 — CHj — OH CH3— CHj — SH.

Ethyl Alcohol. Ethyl Mercaptan.

Likewise, the trivalent elements, like nitrogen and phosphorus,
may unite with carbon with all or with one affinity — either with one
carbon atom —

CH, — N^y CO = NH CH = N

Ethylamine. Carbimide. Hydrogen

Cyanide.

or with two or three carbon atoms : —

CH3 \

)NH CH3 — N

CH,

/

Dimethylamine. Trimethylamine.

In this way two or more carbon atoms may be united to a mole-
cule through the agency of an element of higher valence.

Those isomeric bodies (of like composition) containing several
different carbon groups, held in combination by an atom of higher
valence, are termed metameric. Examples are —

£^» ^O and ^S^^O, also

Methyl- Diethyl

opyl Ether. Ether.

1 CH3 1 C3H,-)

\ N C2H5 In and H I ]

i H J H j

Methyl- Diethyl

propyl Ether. Ether.

CH3-) CHg ■) CgH,

CHj \ N C,Hs ^ N and H S- N

Trimethylamine. Methylethylamine. Propylamine.

CHEMICAL STRUCTURE OF CARBON COMPOUNDS.

45

These can be resolved by various reactions into their component
carbon groups (or their derivatives), and inversely be synthesized
from these groups or their derivatives.

Law of Even Numbers. — In every carbon compound, the sum of
the elements of uneven valence (of the monads and triads), like
H, CI, Br, and N, P, As, is an even number. Thus, in cyanuric
acid, C3H3N3O3, the sum of the hydrogen and nitrogen atoms = 6 ;
in ammonium trichloracetate, C2CI3 (NHJOj, the sum of the atoms
of CI, N and H = 8. This law, established empirically at first,
and of importance in the deduction of chemical formulas, finds, at
present, as observed in preceding lines, a simple explanation in the
quadrivalent nature of carljon and the property of the elements to
unite themselves by single affinities.

Radicals and Formulas. — Radicals or residues are atomic
groups remaining after the removal of one or more atoms from
saturated molecules. Ordinarily, radicals are groups containing
carbon, while all others, like O, SH, NHj, NOj, are residues or
groups. By the successive removal of hydrogen from the hydro-
carbons of the formula CnHjn + a. radicals of difierent, increasing
valence result. These may combine with other elements or groups

until the form C„H,

n-^-'Jn + J

is attained :-

C/3

<
o

5

Molecules.

univalent.

bivalent.

trivalent.

quadrivalent.

Methane.

CH3
Methyl.

CH,

Methylene.

CH
Methine.

c

Carbon,

CzHg

Ethane.

Ethyl.

Ethylene.
C2H3
Vinyl.

Acetylene.

CsHg
Propane.

C3H,

Propyl.

C3H5
Propylene.

C3H5
Glyceryl.

C3H4
AUylene.

Butane.

CjHg.

Butyl.
C^Hg

Butylene.

C4HT,

Crotonyl.

Crotonylene.

It may be observed from the preceding pages, that radicals are
not capable of existing free. When the univalent radicals separate
from their compounds they double themselves : —

CH3I
CH3I

2 mols. Methyl
Iodide.

CH3

+ 2Na = I + 2NaI.

CH3

Dimethyl.

The bivalent and quadrivalent radicals can only be isolated from
their compounds when the affinities that are liberated belong to
two adjacent carbon atoms — that is, those mutually uniting each
other : —

CH^Cl
CHjCl .

Ethylene
Chloride.

+ 2Na = 2NaCl +

CH„

II
Ethylene.

46 ORGANIC CHEMISTRY.

The radical CH3 — CH =: cannot be isolated from CH3 — CHClj
(comp. p. 42).

As in the examples just given, acetylene may be obtained from
dichlorethylene : —

CHCl

CH

II + 2Na =

III + 2NaC),

CHCl

CH

lichlorethylene.

Acetylene.

The acceptance of radicals leads to a special nomenclature of
the compounds. Monochlorethane, QHsCl, derived by substitution
from the molecule of ethane, CaHs, may be viewed as a compound
of the group ethyl with chlorine, hence, called Ethylchloride.
C2H2CI2 is called dichlormethane or methylene chloride ; C2H5NH2 is
known as amidoethane or ethylamine, etc. For this reason it is
customary to ascribe especial names to the simpler and more fre-
quently occurring radicals or atomic groups (see above). Alco-
holic radicals or alkyls is the name applied to the univalent radicals
Cja^u + u from their most important compounds — the alcohols,
CoH2o^.iOH. Those groups that are bivalent are called alkylens,
etc.

The univalent radicals are again distinguished s& primary, second-
ary and tertiary, according as the unsaturated carbon atom is
attached to one, two or three carbon atoms : —

CH3 - CH2 - CH2 - 8h /CH - (<^H3)3C -

Primary Propyl. Secondary Propyl. Tertiary Butyl.

These correspond to the primary, secondary and tertiary alcohols
(see these).

Structural formulas are those indicating the complete grouping
of all the atoms : —

CH, — CHj — CH2.OH ch'/^^ ~ '^^

Primary Propyl Alcohol. Secondary, or Isopropyl Alcohol.

They are a representation of the whole chemical deportment of
a given compound. The rational or constitutional formulas only
indicate the union of individual atoms — such as are especially
characteristic of the compound. Thus, the formula C3H,.0H indi-
cates that the body is an alcohol ; has properties common to all
alcohols ; it leaves undetermined, however, whether it is a primary
or a secondary alcohol. For simplicity we employ siich formulas
and assign special names to the isomeric radicals. The empiric or
unitary formula CjHgO affords no hint as to the character of the
compound, since it belongs to an entire series of bodies that are
isomeric, yet wholly different.

CONSTITUTION OF CARBON COMPOUNDS. 47

EARLY THEORIES RELATING TO THE CONSTITUTION OF THE CARBON

COMPOUNDS.

The opinion that the cause of chemical afHnity resided in electricil forces,
came to light in the commencement of this centnry, when the remarkable decompo-
sitions of chemical bodies, through the agency of the electric current, were dis-
covered. It was assumed that the elementary atoms possessed different ele;trical
polarities, and the elements were arranged in a series according to their electrical
deportment. Chemical union depended ot the obliteration of different electri-
cities. The dualistic idea of the constitution of compounds was a necessary
consequence of this hypothesis. According to it, every chemical compound was
composed of two groups, electrically different, and these were further made up of
two difiFerent groups or elements. Thus, salts were viewed as combinations of elec-
tro-positive bases (metallic oxides), with electronegative acids (acid anhydrides),
and these, in turn, were held to be binary compounds of oxygen with metals and
metalloids. (See Richter's Inorganic Chemistry.) With this basis, there was
constructed the electro-chemical, dualistic theory of Berulius. This prevailed
almost exclusively in Germany, until about i860.

The principles predominating in inorganic chemistry were also applied to
organic substances. It was thought tliat in the latter complex groups (radicals)
pre-existed, and played the same role that the elements did in mineral mxtter.
Organic chemistry was defined as the chemistry of the compound radicals (Liebig,
1832), and led to the chemical-radical theory, which flourished in Germany
simultaneously with the electro-chemical theory. According to this view, the
object of organic chemistry was the investigation and isolation of radicals, in the
sense of the dualistic idea, as the more intimate components of the organic com-
pounds, and by this means they sought to explain the constitution of the latter.

In the meantime, about 1830, France contributed facts not in harmony with
the electro-chemical, dualistic theory. It had been found that the hydrogen
in organic compounds, could be replaced (substituted) by chlorine and bromine,
without any apparent change in the character of the compounds. To the electro-
negative halogens was ascribed a chemical function similar to electro-positive
hydrogen. This showed the electrochemical hypothesis to be erroneous. The
dualistic idea was superseded by a unitary theory. Laying aside all the primitive
speculations on the nature of chemical affinity, the chemical compounds began to
be looked upon as constituted in accordance with definite mechanical ground-forms
— types — in which the individual elements could be replaced by others (early-type
theory of Dumas, nucleus theory of Laurent). At the same time the dualistic view
on the pre-existence of radicals was refuted. The correct establishment of the ideas,
equivalent, atom and molecule {"Lwir&ni and Gerhardt), was an important conse-
quence of the typical unitary idea of chemical compDunds. By means of it a cor-
rect foundation was laid for further generalization. The molecule having been
determined a chemical unit, the study of the grouping of atoms in the molecule be-
came possible, and chemical constitution could again be more closely examined.
The investigation of the reactions of double decomposition, whereby single atomic
groups (radicals or residues) were preserved and could be exchanged (Gerhardt) ;
the important discoveries of the amines or substituted ammonias by Wurtz (1849),
and Hofmann (1850); the epoch-miking researches of Williamson, ujjon the
composition of ethers, and the discovery of acid-forming oxides by Gerhardt —
these all contributed to the announcement of the type theory of Gerhardt (1853),
which was nothing more than an amalgamation of the early type or substitution
theory of Dumas and Laurent with the radical theory of Berzelius and Liebig.
The molecule was its basis — and to it there was attached a more extended grouping
of the'atoms in the molecule. The conception of radicals became different. They
were no longer regarded as atomic groups that could be isolated and compared

48 ORGANIC CHEMISTRY.

with elements, but as molecular residues which remained unaltered in certain
reactions.

Comparing the carbon compounds with the simplest inorganic derivatives,
Gerhardt referred them to the following principal fundamental forms or type: —

E}

en

h;

Hydrogen.

Hydrogen
Chloride.

g}0 gJN

Water. H J

Ammonia.

From these they could be obtained by substituting the ccmpound radicals for
hydrogen atoms. All compounds that could be viewed as consisting of two
directly combined groups were referred to the hydrogen and hydrogen chloride
types, e. g. .•—

C.H.J

^^^^f}

CN\
H/

CN

C.H3OI

Ethyl

Ethyl

Cyanogen

Ethyl

Acetyl

Hydride.

Chloride.

Hydride.

Cyanide.

Chloride.

It is customary to refer all those bodies derivable from water by the replace-
ment of hydrogen, to the water type; /'. c, those in which two groups are united
by oxygen : —

CjHs")^ CaHaOl^ C^Hjl^-, CjHjOIq

H r ^ H ; "' CjH= f " CjHjO / ^

Alcohol. Acetic Acid. Ethyl Ether. Acetic Anhydride.

The compounds containing three groups united by nitrogen are considered
ammonia derivatives: —

CH,-| CH,^ qHjOl „o

These types no longer possessed their early restricted meaning. Sometimes a
compound was referred to different types, according to the transpositions the
formula was intended to express. Thus aldehyde was referred to the hydrogen or
water type ; cyanic acid to the water or ammonia type : —

C,H,0

} -<> "^^'}0. ^l]0 and COJ,

The development of the idea of polyatomic radicals, the knowledge that the
hydrogen of carbon radicals could be replaced by the groups OH and NHj, etc.,
contributed to the further establishment of multiple and mixed types : —

Compound Types: —

Ha

H,1

e.g.:—

Cll

Ethylene Chloride.

^io
h}o

CO";

hJn

Ethylene

Carbamide,

Glycol.

THEORIES RELATING TO STRUCTURE. 49

Mixed Types : —

hJ ■' h}o HJO

Chlorhydrin. Oxamic Amido-acetic Acid.

Acid,

The manner of arrangement finding expression in these multiple and mixed
types was this : two or more groups were united into one whole — a molecule — ^by
the univalent radicals. Upon comparing these typical with the structural formulas
employed at present, we observe that the first constitute the transitional state from
the empirical to the unitary formulas of the present day. The latter aim to express
the perfect grouping of the atoms in the molecule. By granting a particular
function to the atoms — their atomicity or valence — Kekuld (1858) indicated the
idea of types ; the existence and combining valence of radicals was explained
by the tetravalence of the carbon atoms, and their tendency to mutually combine
with each other, according to definite affinity units (KekulS and Cooper). The
type theory, consequently, is not, as sometimes declared, laid aside as erroneous;
but it has only found generalization and amplification in a broader principle — just
as the present structural theory will, at some future lime, find wider importance in
a more general hypothesis which encompasses the nature of chemical affinity.

RECENT VIEWS RELATING TO THE THEORY OF STRUC-
TURE.

The theories now extant, relating to the manner in which the
atoms are connected, do explain in a great measure the isomerisms
and the behavior of carbon derivatives, yet they fail to give a com-
plete picture, inasmuch as they do not touch, or even attempt to
convey any idea as to the spatial relations of the atoms. Nor do
they include any explanation of the nature of chemical affinity
(p. 38). The instances, in which the ordinary structural formulas
do not satisfy the actual relations, have become so numerous, that
additions must be made to our structural theory, and many parts of
it wholly recast. This cannot be deferred any longer. Two series
of phenomena demand it.

The one series comprises all cases in which one and the same struc-
tural formula must be assigned two or more different compounds.
Heretofore, such derivatives were regarded as physical isomerides.
They were explained by assuming them to be different aggregations
of molecules which were chemically similar. At present many
different compounds are known to which one and the same struc-
tural formula must be assigned. For example, the two oxy-pro-
pionic acids, CH3. CH(OH). CO-^H (lactic acid, and sarco-lactic

50 ORGANIC CHEMISTRY.

acid), the two acetylene dicarboxylic acids (fumaric and maleic
acids), the three dioxy-succinic acids (dextro-, laevo- and inactive
tartaric acid), etc. Isomerides of this kind, different from the
ordinary, may be formulated as alloisomeric bodies ; the phenomenon
is termed alloisomerism (Michael, Ber., ig, 1384). An explanation,
for these phenomena, has been sought in the spatial relations of the
atoms, hence we speak of a spatial or geometrical isomerism, and of
stereochemical formulas. For the term constitution or structure is
substituted the phrase configuration of the molecules. The word
position corresponds to the old term union (linking) (J. Wislicenus,

In the second ^Qxi?:^ of phenomena are mcluded all compounds to
which two different structural formulas may be rightly attributed.
Such formulas are tautomeric. Tautomerism is explained- by the
assumption of motion of atoms between two positions (points) in
equilibrio (Laar, p. 54).

STERKOCHEMICAL THEORIES.

As the assumption that the four atoms or groups, combined with
one carbon atom, are arranged or lie in the same plane, leads to a
far greater number of isomerides than are known, and as isomerides
corresponding, e.g., to the two planimetric and different atomic
arrangements

a b

I I

a — C — b and a — C — a

L I

have not been proved to exist, the structural theory makes no attempt
to interpret spatial relations, but confines itself to the union of
atoms in definite successive series. Le Bel and van't Hoff (1874)*
were the first to demonstrate in what manner the actual relations
might be made to harmonize with these representations. Their
assumptions are embodied in the three following propositions : —

(i) The four affinities of the carbon atom, while separated in
space, are arranged like the summits of the tetrahedron. The union
of other atoms consists in the attachment of the same to these sum-
mits (tetrahedral angles). Hence, isomerides can only occur when
the carbon atom is combined with four different monovolent groups.
In such instances two isomeric derivatives C a b c d are possible.
This is evident from an inspection of the tetrahedron model, and
stands proved by the existence of, for example, two a-oxypropionic

* van't Hoff-Herrmann : "Die Lagerung der Atome In Raum," 1877. van't
Hoff: " Dix Annies dans I'hiitoire d'une tlieorie." 18S7.

STEREOCHEMICAL THEORIES. 5 I

acids, CH3.CH(OH). CO^H. Carbon atoms of this kind, linked
to four different groups, are called asymmetric (represented by an
italic C). This representation is chiefly employed by Le Bel and
van't Hoff* to explain the optical rotatory power of the derivatives
of carbon (p. 63).

(2) Single linking (union) between two carbon atoms occurs when
two tetrahedra unite and have a pair of summits in common. The
resulting form is a double pyramid, with six solid angles, to which
the remaining six groups of the general formula, abcC — Cdef,
attach themselves. This representation gives rise to a series of iso-
merides, greater in number than is known, or even probable ; there-
fore van't Hoff assumes that the two tetrahedra, united with each
other, rotate about a common axis, and that isomerism can only
occur when the rotating systems are different. Compounds, with
six different groups, abcC — Cdef, could then occur in four different
forms. By doubling each of the three different. groups — in accord-
ance with the formula, abcC — Cabc, as in dioxy-succinic acid (tar-
taric acid) and dimethylsuccinic acid, three isomerides are possible
for each. Compounds of the formula aabC — Cabc, as oxysuc-
cinic or malic acid, can exist in two isomeric modifications each,

CH2. COOH
etc., while succinic acid, | (on rotating the octahedron),

CH,. COOH
cannot possibly have any isomerides.

(3) The double linking (union) of two carbon atoms is repre-
sented by two tetrahedra having two summits in common (by an
edge each.) The two previously rotating tetrahedra are now ar-
rested, and isomerisms are therefore possible, where they could not
formerly occur when they were united by single bonds. Thus, the
compounds abC = Cab (or abC = Cac) must exist in two isomeric
modifications each, the one in which similar groups are arranged
upon the same side (maleic acid), or that in which they are on oppo-
site sides (fumaric acid) : —

CO^H

The same idea is expressed in a simpler way, as follows :

(i) HC. CO2H (2) HOjC. CII

and II

H HC. COJI.

* JHd.

A.

52 ORGANIC CHEMISTRY.

The first formula allows maleic acid to form an anhydride. Fumaric
acid is not adapted thereto, because of the distance between the
two carboxyls.

Triple union of two carbon atoms is represented by two tetra-
hedra, with three pairs of common summits (according to van't
Hoff ) — that is, each tetrahedron presents one of its plane surfaces.
Geometrical isomerides are not possible for the compounds aC ^ Cb.
This is also the case with the structural formulas.

These ideas, first employed by Le Bel and van't Hoff almost
exclusively for the purpose of explaining the optical activity of the
carbon compounds (p. 63), have been given more recently a
broader development, through the labors of J. Wislicenus*; they
have been especially applied in the interpretation of chemical rela-
tions. This has been achieved by the introduction of two new
theories bearing upon the manner (kind) of the additive-reactions
of the unsaturated ■ carbon compounds, and also upon the mutual
influence of the groups in union with carbon.

C. CO2H

For example, begin with acetylene dicarboxylic acid, ||

C. CO^H.
In this, the two carbon tetrahedra have three summits in common.
When addition products are formed, the groups added must be
attached upon the same sides of the tetrahedra (just as is the case
with the two carboxyls). The addition of two hydrogen atoms,
therefore, to the acetylene dicarboxylic acid would produce maleic
and not fumaric acid. In the stereochemical formulas corresponding
to these acids (see above), the position of similarly named groups in
formula i is designated plane-symmetrk , in formula 2 (that of fuma-
ric acid) it is called central or axially-symmetric. The positions on
the same sides of the tetrahedra are also termed corresponding.

Additions occur with the " double linking" of carbon atoms, just
the same as in the case of " triple linking." The added groups
occupy corresponding positions. The addition of hydrogen to maleic
and fumaric acids gives rise to two different configurations : —

(i) H. CH. CO2H (2) HO2 C. H. CH

II ^''^ II

H. CH. COjH H. CH. Q.O^.

corresponding to two isomeric succinic acids. When, however, the
" double linking " is broken, the tetrahedra which, previously, were
stationary, become movable and revolve about their common axis,
and for this reason isomerism is impossible (according to van't Hoff).
Wislicenus maintains, however, that singly-linked tetrahedra can
become fixed in position, and that in consequence there will result

* J. Wislicenus, Ueber die raumliche Anordnung der Atome, 1887.

STEREOCHEMICAL THEORIES. 53

a partial rotation (about 1 20°) of the same. This is induced by the
mutual action or influence of the elements or groups in union with
the carbon atoms, in which case like-named groups (positive or
negative) repel, and those that are unlike, strive to approach one
another. In the plane-symmetric formula (i) given above, the
two carboxyls and the hydrogen atoms, occupying corresponding
positions, repel each other and produce a rotation of the system,
which reaches to the axially-symmetric position (formula 2). The
latter configuration is the preferable one ; therefore, the more stable,
or the bnly one that really exists.

K. Auwers and V. Meyer* have made perfectly similar observa-
tions upon the " fixation" of two " singly-linked" tetrahedra. At
the same time they call attention to the fact that compounds of the
general formula aabC — Caab (<?. g. benzil dioxime) can occur in
three'isomeric configurations.

By means of the representations just described, it is possible to
interpret and explain the facts which, in many cases, fall far short
of meeting satisfactory explanation from the structural theory.
However, many and great difficulties yet remain ;f so that, in ap-
plying the stereochemical views, reserve and caution should be used.

It should not be forgotten that even the new doctrine includes no
explanation for, or representation of, the nature of chemical affinity ;
hence, like the structural formulas, it gives but an imperfect
formulation of actual facts. The basis of this theory, that the
" double " and " triple linking " is dependent upon a more inti-
mate, therefore more stable position or arrangement of the atoms,
is rather questionable, as it is well established that the unsaturated
compounds possess greater specific volume, greater heat of combus-
tion, less stability, etc., than those that are saturated (p. 5 7). There-
fore, the stereochemical doctrine can only be regarded as an empiri-
cal amplification of the theory of atomic linking. Like the Ptolemaic
epicycles, it can have but a restricted, temporary value.

V. Meyer and E. Riecke have also developed a hypothesis upon
the linking of atoms (jBer., 21, 946) ; it, however, leaves the nature
of chemical affinity undisturbed, and for that reason further deduc-
tions do not follow from it. A. Baeyer seeks to evolve a mechanical
representation upon the polyvalent and ring-shaped union of the
carbon tetrahedra by assuming the deviation of the points of attrac-
tion. The tensions thus induced correspond approximately to the
variable stability and heat of combustion of these compounds (^i?r. ,
18, 2278).

* Ber., 21, 790,948,3511.

t Aronstein, Ber., ai, 2831 ; Hell, Ber., 22, 57 ; v. Miller, 22, 1713; Michael,
Jmir.p: Chem., 38, i. Compare Annalen, 248, 342; Anschiitz, Ann., 254, 170;
L. Meyer, Ann., 247, 251.

54 ORGANIC CHEMISTRY.

THE TAUTOMERIC THEORY.

Those cases in which, according to the structural theory, two
formulas are possible, while but one corresponding compound is
known, contradict the idea of alloisomerism. If we build up the
compound corresponding to the formulas by means of synthetic re-
actions, two different products are not obtained. On the contrary,
but one results. Conversely, such bodies frequently react, in different
reactions, in two different directions as indicated by the formulas.
Therefore, such formulas seem to be identical — tautomeric — and in
tautomeric compounds the atoms appear to hold an alterable position
(Laar, Ber., i8, 730; Rathke, Ber., 20, 1057). Examples of this
class are : —

^N
^

NH

./ f^

0

and 0

0 and ^

^OH

^^0

^NHj NH

Cyanic Acic

[. Isocyanic Acid.

Cyanamide. Carbdi-imide.

— CH

— CH^

— NH — N

II

and 1

1 ■ and ' II

— C.OH

—CO

—CO — C.OH

Hydroxylform.

Ketoneform.

Lactam. . Lactim,

•^bHi^OH *""^

CsHj. N : N CjHj. NH. N
1 and 1
CioHj. OH C,„H,=0

Nitrosophenol.

Quinone-oxime.

Phenyl-azonaphthol. Naphtho-quinone-
phenyihydrazone.

From their formulas, these compounds are apparently different ;
in reality, they are identical. Laar assumes that the cause of this
is to be ascribed to a mobile- (hydrogen) atom oscillating between
two points in equilibrio, and thereby rendering the entire aggrega-
tion movable. This phenomenon Laar styles tautomerism, while
others designate it desmotropy (Ber., 21, 2228). The replacement of
this hydrogen atom of tautomeric bodies by less mobile alkyls
gives rise to the isomerides of the tautomeric compounds.

A. Baeyer opposes the preceding idea by maintaining that there
is but one definite formula for each compound (Ber., 16, 2188), and
of the tautomeric forms but one will be stable while the other is
unstable and can only exist in its derivatives. The latter form or
modification is designated pseudomeric (see lactams and lactims).
Hantzsch (Ber., 20, 2801, 21, 1754), too, holds that every com-
pound has but one definite structural formula. Tautomeric bodies
(reacting in two directions) can exist in two " phenomenon-forms,"
corresponding to the tautomeric formulas ; these are distinguished
by physical characteristics, and are designated desmotropic conditions

SPECIFIC GRAVITY. 55

(see the ester of hydroquinone dicarboxylic acid). However, it is fre-
quently impossible to fix upon any particular formula for a compound
(see nitrosophenol), or to prove that it exists in two modifications.
Tautomerism, therefore, appears to be the limit, and its desmotro-
pism constitutes the gradual transition to isomerism {£er.,2i, 1857).
In determining questions pertaining to tautomerism, those reactions
only are applicable, from which electrolytic dissociation is excluded
(Goldschmidt, Ber., 23, 253).

PHYSICAL PROPERTIES OF THE CARBON COMPOUNDS.

Usually we can foresee that the physical, as well as the chemical,
properties of the derivatives of carbon must be conditioned by
their composition and constitution. Such a regular connection,
however, has been as yet only approximately established for a few
properties. Those meriting consideration here, serving,' therefore,
chiefly for the external characterization of carbon derivatives,
are the specific gravity in the gaseous and liquid condition,
the melting and boiling temperatures, the behavior towards light,
and electric conductivity.

SPECIFIC GRAVITY.

By this term is understood the relation of the absolute weights
of equal volumes of bodies, in which case we take as conventional
units of comparison, water for solids and liquids, and air or hydro-
gen for gaseous bodies (see p. 29).

For the latter, as we have already seen, the ratio of the specific
gravity (gas density) to the chemical composition is very simple.
Since, according to Avogadro's law, an equal number of molecules
are present in equal volumes, the gas densities stand in the same
ratio as the molecular weights. Therefore, the specific volume, i. e. ,
the quotient of the molecular weight and specific gravity, is a con-
stant quantity for all gases (at like pressure and temperature). The
relations are different in the cases of liquid and solid bodies.
Since in the solid and liquid states the molecules are considerably
nearer each other than when in the gaseous condition, the specific
gravities cannot be, as -with gases, proportional to the molecular
weight, and are also modified by the size of the molecules and their
distance from each other. The size and distance are unknown to
us; the latter increases, too, with the temperature, therefore, the
theoretical groundwork for deduction of specific gravities is far
removed from us. However, some regularities have been empirically
established for the specific gravity of /iguid bodies. These appear,
upon comparing the specific volumes or molecular volumes.

5 6 ORGANIC CHEMISTRY.

In determining the specific gravity of liquid compounds, a small bottle — a pyk-
nometer — is used. Its contracted portion is provided with a mark ; more compli-
cated apparatus is employed where greater accuracy is sought (Annalen, 203, 4).
Descriptions of modified pyknometers will be found in the Handworterbuch v.
Ladenburg, 3, 238. To get comparable numbers, it is recommended to make
all determinations at a temperature of 20° C, and refer these to water at 4°, and a
vacuum. Letting m represent the weight of substance, v that of an equal volume
of water at 20°, then the specific gravity at 20° referred to water at 4°, and a vacuum
(with an accuracy of four decimals), may be ascertained by the following equation
\Annakn, 203, 8) : —

20 m . 099707

d ^— ^ I 0.0012.

To find the specific volumes at the boiling temperature, the specific gravity at
any temperature, the coefficient of expansion and the boiling point must be ascer-
tained ; with these data the specific gravity at the boiling point is calculated, and
by dividing the molecular weight by this, there results the specific or molecular vol-
ume. Kopp's dilatometer {Annalen, 94, 257, compare XVox-^z, Journal Chem. Soc,,,
1880, 141, and Weger, Annalen, 221, 64), is employed in obtaining the expansion
of liquids. For a method of getting the direct specific gravity at the boiUng point,
consult Ramsay, Ber., 12, 1024; Schiff, Ann., 220, 78, and Ber., 14, 2761 ; also
Schall, ^^r., 17, 2201, and Ngubeck, Zeit.fhys. Chem., 1, 651.

H. Kopp ascertained that the following relations existed between
the composition of carbon compounds and their molecular volumes
at the boiling temperature : —

1 . Isomeric compounds possess approximately like specific volumes.

2. Like differences in specific volume correspond to like differences in compo-
sition.

From these data arose the following law : the specific volume of a liquid com-
pound (mol. volume), at its boiling point, is equal to the sum of the specific volumes
of its constituents (of the atomic volumes). This gives to every element a definite
atomic volume in its compounds.

In homologous compounds the difference, CHj, corresponds to a difference of
22 in specific volume, for example : —

Molecular Specific
Weight. Volume. Diflference.

Formic Acid CHjO^ 46 42 | 22

Acetic Acid QH^^ 60 ^4- I 22

Propionic Acid C3H5O2 74 86 J

Butyric Acid C^HjOj 88 108 | 22

The replacement of a carbon atom by two hydrogen atoms, does not cause any
alteration in specific gravity, c. g., —

Molecular Specific

Weight. Volume.

Cymene Ci„H„ 134 187

Octane..... CjHjj 114 187

As the specific volume of the group CII^ equals 22, and the specific volume of one
atom of C is equal to that of two hydrogen atoms, it follows that the specific volume
of one carbon atom (its atomic volume) is II, and that of one hydrogen atom 5.5.
In a similar manner Kopp deduced two different atomic volumes for oxygen. If

SPECIFIC GRAVITY. 57

oxygen be in union with both affinities to one carbon atom (intra-radical), its ato-
mic volume is equal to 7.8 ; but if it be combined (extra-radical) with two different
atoms (as in (CjHj) ^O and C2H5OH), its atomic volume is equal to 12.2. Hence,
the specific volume of a compound of the formula dHbOoO'd (O represents intra-
and O' extra-radical oxygen) may be calculated from the equation : —

Molecular Volume =11 . a -|- S-5 • b -f- 12.2 . c -f- 78 . d.

The other elements exhibit similar definite specific volumes in their compounds,
e. g., chlorine = 22.8, bromine = 27.8, iodine = 37.5. Sulphur, like oxygen,
has two values: the atomic volume of the intra-radical sulphur (in CS) equals
28.6; that of the extra-radical, 22.6. In ammonia and its derivatives, nitrogen has
the specific volume 2.3, in the CN group 17, in NO2, 8.6.

With such data the molecular volumes, and, of course, the specific gravities, can
be obtained with approximate accuracy.

The most recent researches,* based upon an abundance of material, and at the
same time giving due consideration to the structural relations of the carbon com-
pounds, prove conclusively that the supposed regularities, mentioned above, are un-
founded. The fact is, isomeric compounds in no manner have equal molecular
volumes, and their atomic volumes are not constant (Lossen, Ann., 213, 316).
The volume for the difference CHj (see above) is not constant in the different
homologous series, but varies, for example, in the esters of the fatty acids, from 19-28,
and constantly increases with the higher members. Further, the hydrogen volume
is not always 5.5, but it varies according to the manner in which it is derived (see
Ann., 233, 318; Ber., 20, 767). The atomic volume of O is exceedingly variable
(Ann., 233, 322) ; at times the entrance of oxygen into compounds causes a de-
crease in volume (Ber., 19, 1594): —

Vol. Vol.

Toluene, CjHg 103.8 1 Propyl Alcohol, C3H3O 73.4

Benzyl Alcohol, CjHgO 102.1 | Propyl Glycol, CaHgOj 72.1

Another point to be considered is that the comparability of the sp. volumes of
liquid bodies is not fixed by the boiling temperature, because the boiling points are
dependent upon external pressure, and vary very widely in accordance with pressure.
Consequently at temperatures other than that of boiling, similar but varying regular-
ities were observed (Horstmann, Ber., ig, 1579; Lossen, ^«k., 243, loi). Hence
it is (i) that the molecular volumes in nowise represent the sums of the atotiiic
volumes, (2) that the latter are scarcely determinable, (3) that the specific gravities
and molecular volumes depend less upon the volume of the atoms, than upon their
manner of linkage, and upon the structure of the molecules. Therefore to deduce
regularities in the specific volumes it is first necessary to carefully consider the
chemical structure of the compounds. For an exhaustive treatment of these rela-
tions, see Kopp, Ann., 230, 1-117; Ber., 22, Ref., igo. In this connection the
influence of the double union of the C- atoms in the unsaturated compounds and
the ring-form linking in the benzene derivatives, is significant. It has long been
known (Buff) that the molecular volumes of the unsaturated compounds of the
paraffin series were from 1.5-3 greater than those calculated by Kopp. Later
research made them 4.4 (Ann., 220, 298 and 221, 104), which has been confirmed
by Horstmann's most recent investigations (Ber., 19, 1591 and 20, 779). The
divalent union is therefore less intimate (p. 41) and the unsaturated compounds
consequently show a greater heat of combustion (Ann., 220, 320).

* Lossen and others: Ann.,2H, 81,138: 231, 61; 224, 56; 225, 109; 333, 249. 3^6: R- Schiff,
Axn., 230, 113, 278; Horstmann, £er., 19, 1579 ; 20, 766 and 31, 2211. Lossen, Annalen, 343,
1-103.

s

58 ORGANIC CHEMISTRY.

In the conversion of benzene hydrocarbons into their hydrides there is an increase
in volume which is three times as great as in the conversion of the defines into their
corresponding paraffins. This would emphasize the theory that in the benzene
nucleus there are three doubly combined carbon atoms [Ann., 225, 119 and £er.,
20, 771). The specific gravities of the benzene hydrides is notably greater (conse-
quently the molecular volumes are smaller) than their corresponding defines, and
that accounts for the fact that in the ring-linking of the C- atoms in the benzene
nucleus there is an appreciable contraction in volume [Ann., 225, 114 and Ber., 20,
773). P'or further investigations relating to the benzene derivatives see Horstmann,
£er., 21, 2211, and Neubeck, Zeit. phys. Chem., 1, 649.

MELTING POINTS— BOILING POINTS.

Every pure carbon compound, if at all fusible or volatile, exhibits
a definite melting and boiling temperature. It is customary to
determine these for the characterization of the substance.

Boiling Points. These are determined in a so-called boiling
flask, i. e. , a small flask With wide neck, and provided on the side
with an exit tube. The thermometer is fixed in the opening of
the neck by means of a cork. It should not be allowed to dip into
the liquid ; it must only be surrounded by the vapors.

In accurate determinations it is necessary to apply corrections to the indicated
temperatures. If a thermometer is not wholly immersed in vapor, but as ordi-
narily happens, is partly extended into the air beyond the distillation vessel, the
external mercury column will not be heated the same as that on the interior,
hence the recorded temperature will be less than the real. The necessary cor-
rection will be reached with sufficient accuracy by adding to the observed temper-
ature the quantity n (T — t). 0.000154. Here n indicates the length of the mer-
curial column without the vessel, in degrees of the thermometer, T the observed
temperature, t the medium temperature of the air about the external column
of mercury (this is approximately ascertained by holding a second thermometer
about the middle of the exposed part); 0.000154 is the apparent coefficient of
expansion of mercury in glass. The correction is best avoided by having the
entire mercurial column played upon by the vapors of the liquid. Pawlewski
has presented a simple device to effect this [Berichte, 14, 88). It is also appli-
cable in cases where but small quantities of liquid are employed.

If the barometric column did not indicate a normal pressure of 760 mm. during
the distillation a second correction in the observed boiling temperature is neces-
sitated. This is ordinarily accomplished by either adding to or deducting from
the observed temperature 0.1° C. for a difference of every 2.7 mm. between the
observed and normal barometric height (760 mm). This correction is, however,
very inaccurate, because the differences between pressure and boiling point vary
widely for each body [Ber., 20, 709). To avoid this correction it is advisable to
reduce the pressure in the apparatus to the normal. The pressure regulators of
Bunte [Ann., 168, 139) and Lothar Meyer (Ann., 165, 303) are adapted to this
purpose. In distilling under any pressure the forms of apparatus devised by Stae-
del and Schuhmann {Ann., 195, 218 and Ber., 13, 839) will be found very ser-
viceable. For a method, applicable in determining the boiling points of very small
amounts of liquids, see Ber,, ig, 794.

Liquids of different^ boiling points are separated by fractional distillation, an
operation performed in almost every distillation. The portions passing over

MELTING POINTS — BOILING POINTS. 59

between definite temperature intervals (from I-lo°, etc.) are ciuglit apart and
subjected to repeated distillation, the portions boiling alike being united. To
attain a more rapid separation of the rising vapors, these should be passed through
a vertical tube. In this the vapors of the higher boiling compound will be con-
densed and flow back, as in the apparatus employed in the rectification of spirit.
To this end there is placed on the boiling Hask a so-called fractional tube of
Wiirtz. Excellent modifications of this have been described by Linnemann, Le
Bel, Hempel and others. For the action of these boiling tubes see Ann., 224,
259; Ber., 18, Ref. loi, and Ann., 247, 3. It is often required to perform the
distillation in vacuo; and this is best effected by exhausting the boiling cham-
ber. An apparatus answering this purpose is mentioned in Berichte, g, 1870. A
very simple contrivance, regulating the pressure at the same time, is that de-
scribed by F. Krafft (^Berichte, 15, 1693; 22, 823). Also consult Thorne and
Godefroy, Ber., 16, 1327, and 17, Ref. 159; as well as Anschiitz, '■Distillation
under reduced pressure," 1887. Vessels designed for the collection of the distil-
lates have been described by L. Meyer, Ber., 20, 1833, and Brvihl, Ber., 21, 3339.

The connection between the boiling points and chemical consti-
tution of compounds will be discussed later in the several homolo-
gous groups. Generally the boiling point rises with the complica-
tion of the molecule. The unsaturated compounds boil at a higher
temperature than those that are saturated. With isomerides having
an equally large carbon nucleus those of normal structure possess
the highest boiling points. These fall with the accumulation of
methyl groups.

It may also be noted that the lower boiling isomerides possess
a greater specific volume {Ber., 15, 2570).

Melting Points. To determine these, introduce the substance
into a thin, drawn-out tube, sealed at one end. This is attached
to a thermometer and allowed to dip into a small beaker containing
water, or a high boiling compound — paraffin. The beaker is warmed
upon a sand bath until the substance in the little tube melts, and
the temperature noted. For convenient apparatus for this purpose,
see £erichte,lLO, 1800.

The greater part of the mercury column of the thermometer extends beyond
the heated bath, and therefore receives less heat. In all accurate determinations,
a correction for this is consequently necessary. This is done as described with the
boiling temperature. Correction for barometric pressure is not required, because
the melting, points are but slightly affected by pressure.

See Ber., 19, 1970, for a device intended for the direct determination of the
corrected melting point. The melting point is generally rather high if the
melting tube is very narrow. The most accurate results are obtained when larger
quantities of material are used in the determination [Ber., 21, Ref 638).

Very often slight admixtures, which can hardly be excluded,
even by fractional crystallization, will materially lower the melting
point.

The relation between the melting point and the chemical consti-
tution will be more fully considered under the different homologous
groups of bodies.

6o ORGANIC CHEMISTRY.

OPTICAL PROPERTIES.

, Refraction. The carbon compounds (like all transparent sub-
stances) possess a variable light refracting power. In this case, as
in other cases, the quotient of the sine of the angle of refraction (r)
into the sine of the angle of incidence (/) is a constant quantity for
each substance. This number is termed the coefficient of refraction,
or refractive index (n) : —

sin i

sin r

The refractive index of liquids is mostly determined by two methods. In the one
the deviation of a ray of light is noted when it passes through a cylinder filled with
the liquid under examination. The spectrometer of Meyerstein is especially adapted
to this purpose. The second method (that of Wollaston) is less accurate, but much
simpler than the first. It is also applicable to small amounts of substance. It is
based on the total refraction caused by a layer of liquids. This is determined by
means of the refractometer of Pulfrich and Abb6.

The coefficient of refraction (n) varies with the temperature, con-
sequently also with the specific gravity of the liquid.

Their relation was formerly assumed to correspond to the formula
" ~ '» in which d represented the sp. gr. of the liquid for a given
temperature. It is an almost constant quantity for all temperatures,
and is called the specific refractive power. However, later re-
search has proved that the theoretically deduced equation, ° ~ '
(the so called n'-formula), more nearly represents the actual facts
{£er., 19, 2760). It is therefore, at present, applied almost
exclusively.*

On comparing the refractive constants (using the n — 1 or n* —
formula) of a mixture of several liquids with those of the con-
stituents, it will be discovered that the first equals the sum of
the refractive constants of the latter, and corresponds to their

* For a more accurate representation of these relations, see Landolt, Pogg. Ann.,
123, 595 ; Ber., 15, 1031 ; Bruhl, Ber., 19, 2746 and 2821 ; Ann., 235, 1, and 236,
233; Ber., 20, 2288, and Zeit. phys. C/iem., i, 307; Wiegmann, Zeit. phys. Chem.,
I, 218 and 257; Ketleler, ibid., 2, 905.

The refractive index (n) can be referred to any wave-length that may be desired.
Since, however, different substances have different dispersive power, such indices
are not directly comparable, and they were, therefore, referred to rays of infinite
wave-length (accordmg to Cauchy's dispersion formula). The indices supposed to
be freed from the influence of dispersion were represented by the letter A, and the

refractive constants by and ■• The most careful investigations

d (A2 + 2)d ^

have shown that these assumptions possess neither theoretical nor empirical value,
and on that account it is necessary to come back to the refraction of one definite
ray. Therefore, either the yellow sodium line (D of the sun's spectrum) or the
red line of hydrogen Ha (C of the sun's spectrum) may be used.

OPTICAL PROPERTIES. 6 1

percentage content in the mixture. A similar relation exists for
chemical compounds. Designating the product of the specific re-
fractive power of a compound R (according to n — or n'' — for-
mula), the molecular weight M as the molecular refraction, and the
product of the refractive index of the elements and their atomic
•^^\^\s,, \!vA atomic refraction, \}PA proposition would read: "The
molecular refraction of a liquid carbon compound is equal to the
sum of the atomic refractions," corresponding to the equation : —

MR = amr -|- bmV ■\- cm."!",

in which a, b, c, represent the number of elementary atoms in the
compound. The atomic refractions of the elements are deduced
from the molecular refractions of the compounds obtained empiri-
cally, in the same manner as the atomic volumes are obtained from
the molecular volumes (see p. 5,7).

While it was formerly assumed that but one atomic refraction
existed for each element in its compounds, later researches have
proved that the atomic refraction of the polyvalent elements is in-
fluenced by their manner of union. The following atomic refrac-
tions have been calculated for the red hydrogen ray, Ha, and the
formula " ~ ' {Briihl, Ann., 235, 35, and Conrady, Ber., 32, Ref.
224) ; "singly linked " carbon has the atomic refraction* (r^) equal
to 2.48, hydrogen 1.04. chlorine 6.02, bromine 8.95. Oxygen has
two "atomic refractions." When it is united by one bond to car-
bon (as hydroxyl, and in ethers), the constant is 1.58 (1.52 and 1.68
for the line D), while in its double union (in C = 0) it is 2.34.
Similarly, sulphur exhibits two different values {Ber., 15, 2878).

The deportment of double- and treble-linked carbon atoms is
worthy of note. The double union (C, ^), according to Briihl, is
1.78 (for r^), that of the triple union (Q^) 2.18, i. e., if two car-
bon atoms are " doubly linked," their atomic refraction equals
2X2.48-]- i.78 = 6..74,whileintripleunionit is4.96-(- 2.18=7.14.

These relations have met with frequent application in the decision
of questions pertaining to chemical constitution. Thus the greater
molecular refraction (by 3X i- 78 = 5.34units) of the benzene bodies,
confirms the view previously deduced from chemical facts, that
there is present in the benzene nucleus three " double-linked " car-
bon atoms {Ber., 20, 2288). However, the regularities noted above
only hold good for bodies with slight dispersive power (the fatty
bodies). In the case of substances possessing a greater dispersive
power than cinnamyl alcohol, the molecular refraction is valueless
for the determination of chemical structure {Ber., 19, 2746).

* The molecular refraction of a ray of indefinite wave-length (index A) is
designated by R^, the atomic refraction by r^.

62 ORGANIC CHEMISTRY.

Rotation of the Plane of Polarization.*— Many carbon
compounds, liquid and solid, are capable of rotating the plane of
polarized light. These are chiefly naturally occurring substances,
like the various vegetable acids, amyl alcohol, the sugars, carbo-
hydrates and glucosides, the terpenes and camphors, allcaloids and
albuminoids ; they are said to be optically active. The rotation
(of the angle a) is proportional to the length 1 of the rotating plane,

hence, the expression " is a constant quantity. To compare sub-
stances of different density, in which very unequal masses fall upon
the same plane, these must be referred to like density, and hence,
the rotation must be divided by the sp. gr. of the substance at a

definite temperature. The expression _^ = [a], in which the

1-" d

length of the rotating plane is giv€n in decimeters, is called the

specific rotatory power of a substance at a definite temperature and is

designated by [a]„ or [a]j, according as the rotation is referred to

the yellow sodium line D or the transitional color j. For solid,

active substances, with an indifferent solvent, the expression

[a] := ''°° ° will answer ; in this p represents the quantity of

p ■ 1 • d
substance in loo parts by weight of the solution, and d represents
the specific gravity of the latter.

The specific rotatory power is constant for every substance at a definite tem-
perature; it varies, however, with the latter, and is also influenced more or
less by the nature and quantity of the solvent. Therefore, in the statement of
the specific rotatory power of a substance, the temperature and the percentage
amount of the solution must be included. By investigating a number of solu-
tions of different concentration, the influence of the solvent may be established and
the true specific rotation or the true rotatory constant of the pure substance,
designated by A„, may then be calculated. The product of the specific rotatory
power and the molecular weight / divided by lOO is designated the molecular
rotatory power : —

[M] =IM

lOO

Consult Ber., 2i, 191, 2586, 2599, upon the influence of inactive substances on
the rotatory power.

In crystalline substances, the rotatory power is connected with
the crystalline form, and is usually conditioned by the existence of
hemihedral planes {see Tartaric Acids). As the activity of most of
them is retained by solution, or is then first perceptible, it is sup-
posed that crystal molecules exist in the solution, and that these
consist of a union of several chemical molecules. Since, further,

* Compare Landolt, " Das optische Drehungsvermogen," 1879.

OPTICAL PROPERTIES. 63

numerous solids and liquids are known in dextro- and Isevo-rotatory
and inactive modifications, in which we can detect no difference in
chemical structure, besides the active modifications mostly con-
vertible into inactive, it was concluded that the activity was caused
not by single chemical molecules, but by groups ol physical mole-
cules. These were termed physical isomerides. Since we have as-
certained that turpentine oil and camphor, in the form of vapor,
possess the same specific rotatory power as when they are in the
liquid or solid state, and inasmuch as optically different substances,
having the same structural formula, possess the same molecular
weight, it can no longer be doubted that the activity is induced by
a peculiar, chemical atomic-grouping, which finds no expression in
the structural formulas usually offered. Le Bel and van't Hoff *
deserve the credit of having advanced a theory, based on the spatial
relations of atoms, that succeeds in bringing the latter and the
optical rotatory power into full harmony.

According to this theory, the activity of the carbon compounds is dependent upon
the presence oi asymmetric carbon atoms, i. e., such as are combined with different
atoms or atomic groups.

In all cases of this nature, every compound C a b e d, having its four groups
arranged like the four solid angles (summits) of a tetrahedron, can have two possible
configurations, the one being nothing more than the reflected image of the other.
These forms are not superposable. There are two corresponding isomerides for
each of these forms. These all agree perfectly in their chemical behavior, and
differ from each other only in their opposite rotatory power, and opposite
hemihedral (enantiomorphous) crystalline forms (see Tartaric Acids).

The following are examples of those compounds in which one asymmetric
carbon atom is present : —

CH3. CH(OH)COjH C2H5. CH(CH,)COjH CjHj. CH(CH3). CH,OII

Ord. Lactic Acid. Active Valeric Acid. Active Amyl Alcohol.

CH(OH). CO^H CH(NH2). CO^H CH(NHj) . CO^H

CH,. CO^H CH^. CO. NHj. CH,. CO^H, etc.

Malic Acid. Asparagine. Aspartic Acid.f

Each of these compounds can occur in a. dextro- and Itevo- rotatory modification.
What is more, the oppositely active forms can combine in equal quantities with
each other, and produce an inactive double form, capable of re-solution into two
active varieties (p. 64). Therefore, compounds containing one asymmetric carbon
atom can give rise to three isomerides — two of which are active, and the third
inactive, but capable of further division.

When two asymmetric carbon atoms are present in a compound, the number of
possible iiomerides is correspondingly greater. If the entire six groups in union
with the two carbon atoms are different, corresponding to the general formula
abcC — Cdef, then four different configurations (p. 51) can exist, two of

* van't Hoff, " Dix ann^es dans I'historie d'une thSorie,'' 1887.
f The asymmetric carbon atoms are indicated by an italic C.

64 ORGANIC CHEMISTRY.

which will be opposite and active. If each of the two carbon atoms are in union
with three similar groups, as in tartaric acid —

CH(OH). COjH

CH(OH). CO2H

three configurations are possible for each : a dextro- and Icsvo- form, as well as an
inactive modification not capable of division. This is known as the anti-modifica-
tion ; in it the three groups are diametrically opposed to each other, and there re-
sults an inner compensation. Besides these there is also the inactive ox para-form,
resulting from the union of the two active varieties; this can be separated again
into its components. Hence, tartaric acid may occur in four isomeric modifica-
tions, while malic acid yields but three isomerides (see above). The inactive form,
capable of further division, is not possible in this instance.

Further research has fully confirmed the deductions of Le Bel and van't Hoff,
so that at present it is an established fact that all known active substances contain
asymmetric carbon atoms; conversely, it has repeatedly occurred that asymmetric
compounds, previously known only in their active- form, have been split up into
their components (see tartaric acid, lactic acid, mandelic acid), while compounds,
not asymmetric, have never yet undergone such a separation (Ann., 239, 164).

On converting active substances into other derivatives, the activity is retained,
providing asymmetric carbon atoms are present ; when they disappear the deriva-
tives are inactive. Thus, from the two active tartaric acids are derived the two
corresponding active malic acids ; whereas, the symmetrical succinic acid, ob-
tained from the latter by further reduction, is inactive. Again, active amyl iodide
affords an active ethylamyl and diamyl ; on the other hand, an inactive amyl
hydride (see Active Amyl Alcohol).

The asymmetric compounds, prepared by artificial means from inactive sub-
stances, are almost always inactive. This is explained by the fact that both
modifications are found simultaneously and in like amounts; further, they also
have the tendency to combine into inactive conglomerates. To this must be
added that energetic reactions, or heat, tend to change the active into the inactive,
decomposable variety («. g., dextro-tartaric acid changes at 175° into raceraic
acid) ; consequently the active variety formed is eventually changed to the inac-
tive. Thus, when the albuminates are decomposed on heating them with baryta,
the products are inactive leucine, tyrosine and glutamine, whereas at a lower tem-
perature hydrochloric acid produces the active modifications {Ber., 18, 358).

Artificially inactive, asymmetric compounds can be split into the two active forms.
This spliiting-up may sometimes be effected by the crystallization of salts, as was
first demonstrated by Pasteur (1848) in the case of racemic acid. (See above.)
This decomposition occurs at a fixed temperature, known as the conversion tempera-
ture ; it is also dependent upon the solubility of the salts {Ber.,ig, 2148 and 2975).

The decomposition of inactive substances takes place more readily by the inter-
vention of other active substances (especially cinchonine and quinine). This, too,
was first observed by Pasteur with racemic acid. It seems to be due to the ten-
dency of the active substance to unite itself exclusively with an active form of the
inactive compound. By the employment of cinchonine not only racemic acid,
but also malic, mandelic and tropaic acids have been thus split up. The splitting-
jip of inactive o-propyl piperidine into active conine, and that of methyl- and
ethyl-piperidine, was effected through the use of active tartaric acid (.5,??-., 20, 339).

A third procedure for the splitting-up of these derivatives is noteworthy; it de-
pends upon the action of ferments — especially Penicil/ium glaucum — which re-
sults in the destruction of one of "the active modifications. Under this treatment,
racemic acid yields Ijevo-tartaric acid (Pasteur), inactive amyl alcohol passes into

ELECTRIC CONDUCTIVITY. 65

dextro-amyl alcoliol, and methyl propyl carbinol and propylene glycol yield their
Isevo-rotatory modifications. Penicillium glaucum or Bacterium termo converts the
synthetic, inactive mandelic acid into its dextro-rotatory form, while Saccharomyces
ellipsoideus orSchizomycetes-fermentation produces the IsEvo-acid {Ber., 16, 1568).
Glyceric acid and ordinary lactic acid {Ber., 16, 2721), as well as leucine and
glutaminic acid, have sustained similar decomposition.

All these observations confirm the proposition of Le Bel and van't Hoff, that the
asymmetrically constituted inactive carbon derivatives can be broken up into two
oppositely active modifications.

ELECTRIC CONDUCTIVITY.

It is well known that substances capable of conducting electricity-
arrange themselves into two widely-separated groups : conductors
of the first class, or those which conduct electricity without sus-
taining any change, and conductors of the second class, or those
which constitute the electrolytes, and conduct only with their simul-
taneous separation into two ions. Conductivity can also be con-
sidered as a resistance, which the conductor opposes to the passage
of the electricity. The customary measure of conductivity or resist-
ance is the mercury unit. This is a column of mercury of one sq.
mm. cross section, and one meter in length, at the temperature 0°.

Ostwald's investigations have demonstrated that the conductivity
of electrolytes is intimately related to chemical affinity. It is a
direct measure of the chemical affinity .of acids and bases. There-
fore, the determination of the conductivity of electrolytes (in aque-
ous solution), to which all organic acids and their salts belong, is of
great interest and importance for all carbon derivatives.

Kohlrausch* has suggested a very simple and accurate means of
determining the conductivity of electrolytes, which has been exten-
sively applied by Ostwald.f

It is dependent upon the application of alternating currents, pro-
duced by an induction spiral, so that the disturbing influence of
galvanic polarization is obviated.

The conductivity of electrolytes is not referred to the percentage
content of their aqueous solutions, but (as the conductivity is ascer-
tained by the equivalent ions) to solutions containing a molecule,
or an equivalent of substance in grams. This value is the molecular
(or equivalent) conductivity of the substance {Zeit. phys. Chem., 2,

567).

The strong acids have the greatest molecular conductivity, then the
fixed alkalies and alkali salts. Most organic acids, on the contrary

* Wiedemann, Ann., 11, 653.

f Journ.pr. Chem., 3a, 300, and 33, 353 ; Zeit.phys. Chem., x, 561.

6

66 ORGANIC CHEMISTRY.

{e.g. acetic acid) are poor conductors in a free condition, while
their alkali salts approach those of the strong acids in conductivity.
The molecular conductivity increases by about 2 per cent, per
degree of temperature. It also increases with increasing dilution,
and in the case of the poor conductors it is far more rapid than with
the good conductors; in both instances it approximates a maxi-
mum (limiting) value. With good conductors this is attained at a
dilution of 1000 litres to the gram-molecule ; while with those poor
in conducting power it is only reached when the dilution is indefi-
nitely large. In fact, in such cases the conductivity is practically
indeterminable.

An interesting observation in connection with the alkali salts of
all acids is the variable increase of the molecular conductivity with,
increasing dilution. This is true both in the case of the strong and
the weak acids (most organic acids belong to the latter class), and it
varies according to their basicity. With sodium salts of monobasic
acids, this increase equals from 10-13 unils, by dilution of 32-1024
litres for the equivalent of substance, for the salts of dibasic acids
from 20-25 units, for those of the tribasic 28-31, for those of the
tetrabasic about 40, and those of the pentabasic about 50 units.
Thus it may be seen that the increase in conductivity of acids, in
their sodium salts, offers a means of determining the basicity and,
consequently, the molecular magnitude of acids (Ostwald, Zeif.
phys. Chem., i, 74 and 97; 2., 901; Walden, Ibid., i, 530, and
2, 49)-

Molecular conductivity has acquired still greater importance by
its application to the measurement of the dissociation of the elec-
trolytes ; it is at the same time the measure of the reactivity or
chemical afiSnity, first, of acids, then bases, and^ finally, of salts.

Arrhenius's electrolytic dissociation theory maintains that in
aqueous solution the electrolytes are more or less separated into
their ions ; this would give a simple explanation for the variations
of solutions from the common laws (under osmotic pressure, under
the depression at the freezing point, etc.). The dissociation is also
manifest in the molecular conductivity, for the latter is dependent
upon the degree of dissociation and the speed of migration of the
free ions ; it is directly proportional to the quantity of the latter.
Molecular conductivity increases with dilution and dissociation.
When the latter is complete, it attains its maximum {jj.^ ). The
degree of dissociation (m) (or the fraction of the electrolyte split
up into ions) for any dilution is found from the ratio of the molec-
ular conductivity at this dilution (/*) to the maximum conductivity
(for an indefinite dilution) : —

/'oo

ELECTRIC CONDUCTIVITY. 67

The latter cannot be directly measured in the case of free organic
acids, because most of them are poor conductors. But it can be
obtained from the molecular conductivity of their sodium salts, by
deducting from their maximum values the speed of migration of the
sodium-ions (41. i), and adding those of the hydrogen-ions (285.8).

Since the molecular conductivity depends upon the dissociation
of the electrolytes into their ions, their alteration by dilution of so-
lution must proceed by the same laws as those prevailing in the dis-
sociation of gases. This influence of dilution or volume (v) upon
the molecular conductivity, or the degree of dissociation (m) is,
therefore, expressed in the equation : —

o

= k,

v(l — m)

which represents the law of dilution advanced by Ostwald {Zeit.phys.
Chem., 2, 36 and 270). This law has been fully confirmed by the
perfect agreement of the calculated and observed values (van't Hoff,
Zeit.phys. Chetn-, 2, 777).

The value, k, is the same at all dilutions for every monobasic acid ;
hence, it is a characteristic value for each acid, and is the measure
of its chemical affinity. The determination of these chemical
affinity-constants by Ostwald for more than 240 acids, has proved
that they are closely related to the structure and constitution of
organic acids {Zeit. phys. Chem., 3, 170, 241, 371).

SPECIAL PART.

The carbon derivatives may be arranged in two classes — the
fatty and aromatic compounds. The name of the first class is
borrowed from the fats and fatty acids comprising it. These
were the first derivatives accurately studied. It would be better to
name them marsh gas or methane derivatives, inasmuch as they all
can be obtained from methane, CH4. They are further classified
into saturated and unsaturated compounds. In the first of these,
called also paraffins, the directly united tetravalent carbon atoms
are linked to each other by a single affinity.

The number of n carbon atoms possessing affinities capable of
further saturation, therefore, equals 2n -\- 2 (see p. 40). Their
general formula is C„X2„ + 2. Here X represents the affinities of the
elements or groups directly combined with carbon. The unsatu-
rated compounds result from the saturated by the exit of an even
number of affinities in union with carbon. According to the
number of affinities yet capable of saturation, the series are dis-
tinguished as C„X.2„, C„X2„_2, etc. (See p. 41-).

All the aromatic or benzene compounds contain a group consist-
ing of six carbon atoms. The simplest derivative of this series is
benzene, CeHg (see p. 42). This accounts for the great similarity
in their entire character. Their direct synthesis from the methane
derivatives is only possible in exceptional cases ; as a usual thing
they cannot be converted into the series CaHj^^z. Their relatively
great stability distinguishes them from the fatty bodies. They are
generally more reactive, yielding, for instance, nitro-substitution
products very readily, and forming various derivatives which the
fatty compounds cannot possibly yield.

The recently investigated trimethylene and tetramethylene de-
rivatives (see p. 42), with which may be included those of furfurol,
thiophene and pyrrol, may be viewed as the transition stage from
the methane compounds containing the open carbon chain, to those
of benzene.

68

HYDROCARBONS. 69

CLASS I.

FATTY BODIES, OR METHANE DERIVATIVES.
HYDROCARBONS.

The hydrocarbons show most clearly and simply the different
manner in which the carbon atoms are bound to each other. We
may regard them as the parent substances from which all other
carbon compounds arise by the replacement of the hydrogen atoms
by differents elements or groups.

The outlines of the linking of carbon atoms were presented in the
Introduction. In consequence of the equivalence (confirmed by
facts) of the four affinities of carbon (see p. 38) no isomerides are
possible for the, first three members of the series CJiia+i : —

CH^ CH3 — CH3 CH3 — CHj — CHj

Methane. Ethane. Propane.

Two structural cases exist for the fourth member, C4H10: —

Normal Butane.

/CH,

and CH— CH3

\CH3

Trimethylmethane.
(Isobutane.)

For the fifth member, pentane, CsHjj, three isomerides are
possible : —

/CH3
CHg — CH2 — Clig — CIij — ^"3 CH — Cra3

Normal Pentane. XCH^ . CH3

Dimethyl-ethyl Methane. and

CII3V ^Cllg

^C^ Telramethyl Methane.

CH,/ \CH3

Hexane, CsHh, the sixth member, has five isomerides (see p. 75).
With reference to the different formulation of these hydrocarbons
see p. 72.

Formation of Hydrocarbons. — The higher paraffins can be grad-
ually built up synthetically from methane, CH,, yet not produced
directly from their elements. Methane itself can be synthesized
from carbon disulphide, CS2 (produced by direct union of carbon
and sulphur on application of heat) by passing the latter, in form
of gas, together with hydrogen sulphide, over red-hot copper : —

CSj + 2H2S + 8Cu = CH4 + 4CajS,

or by heating with phosphonium iodide, PHJ; further, by the
action of chlorine, carbon disulphide may be changed to carbon

70 ORGANIC CHEMISTRY.

tetrachloride, CCI4, and this reduced, by means of nascent hydrogen
(sodium amalgam and water), to methane : —

CCl^ + 4H2 = CH4 + 4HCI,

The direct union of carbon and hydrogen has only been observed
in passing the electric spark between carbon points in a hydrogen
atmosphere ; the product is acetylene, C^Hj, which, with additional
hydrogen (in presence of platinum black), becomes ethylene, CaHj,-
and then ethane, CjHg.

A universal method of producing the hydrocarbons consists in
the dry distillation of complex carbon compounds, like wood,
lignite and bituminous coal. At higher temperatures, e. g. , when
their vapors are conducted through red-hot tubes, the hydro-
carbons can condense to more complicated bodies, hydrogen
separating. Thus, tlie compounds Cjle, C2H4, C^He (benzene),
CioHs (naphthalene), and others, are obtained from CH4, niethane.

A noteworthy formation of the hydrocarbons, especially the
paraffins, is that of the action of hydrochloric acid or dilute sulphuric
acid, and even steam, upon iron carbide.

(I) PARAFFINS OR

ETHANES.

Co

Hjn

+ T

CH4 Methane.
CjHg Ethane.
CgHj Propane.
C^Hjo Butane.
C5H1J Pentane.

CjHjj Hexane.

C,Hij Heptane.

CgEIis Octane.

CgHjD Nonane.

Cii,Hj2 Decane, etc. (see p. 76),

There is no known limit to these hydrocarbons, or the number of
carbon atoms attaching themselves to eachother.

Formerly these hydrocarbons were designated as the hydrides of
the corresponding monovalent radicals or alkyls : CH, (methyl),'
CjHs (ethyl), C3H7 (propyl), etc. (see p. 45), because they were
first obtained from compounds of these with other elements or
groups. Hence the names methyl hydride for methane, ethyl hy-
dride for ethane, etc. The most accessible and first known deriva-
tives of the alkyls, C^Hjo .|. 1, were their hydroxides or alcohols as
C2H5.OFI, ethyl alcohol, and the halogen ethers of the latter.

The following are the most important methods serving to con-
vert the alkyl, CoH^n + i, derivatives into the corresponding hydro-
carbons : —

I. Treat the alkylogens, C„H2„ + i CI (readily produced from the
alcohols, CnHjn + 1 OH), with nascent hydrogen. This may be done

PARAFFINS OR ETHANES. 7 1

by allowing zinc and hydrochloric acid, or sodium amalgam, to act
upon the substance dissolved in alcohol : —

C,H5Cl + H, = C,He + HCI.

Ethyl Ethane.

Chloride. Ethyl

Hydride.

2. Decompose the zinc alkyl compounds with water or the mer-
cury derivatives with hydrochloric acid (compare metallic com-
pounds of the alcohol radicals) : —

^"\C,h' + ^^^'^ = ""^^^ + Zn(OH),.

Zinc Ethyl. Ethyl Hydride.

A more convenient mode of preparation is a combination of both methods :
heat the iodides of the radicals with zinc and water, in sealed tubes, to l20°-l8o°,

3. A mixture of the salts of fatty acids (the carboxyl deriva-
tives of the alkyls) and sodium or potassium hydroxide is sub-
jected to dry distillation. Soda-lime is preferable to the last
reagents: —

CHjCOjNa -I- NaOH = CH, + Na^COj.
Sodium Acetate. Methane

Methylhydride.

When the higher fatty acids are subjected to this treatment the usual products
are the ketones; hydrocarbons, however, are produced when sodium methylate is
used {Ber., 22, 2133).

The dibasic acids are similarly decomposed : —

.COjNa
CeH, / + 2NaOH = C^H,, -|- aCOjNa,.

^COjNa

The hydrides of the radicals obtained by the preceding methods
were distinguished from the so-called y9-i?i? alcohol radicals. These
were prepared synthetically, as follows : —

1. By the action of sodium (or reduced silver or copper) upon
the bromides or iodides of the alcohol radicals in ethereal solu-
tion : — CjHs

2C,H5l-hNa,= | -H2NaI.

Diethyl.

The iodides react in the same manner with the zinc alkyls : —

2C2H5I + Zn = 2 I -f ZnTj.

C2H5/ CjHj

2. By the electrolysis of the alkali salts of the fatty acids in
concentrated aqueous solution : here, as in the decomposition of

72 ORGANIC CHEMISTRY.

inorganic falts, the metal separates at the negative pole, decompos-
ing water with liberation of hydrogen, while the hydrocarbons and
carbon dioxide appear at the positive pole : —

CH3
aCHg.COjK = I + 2CO2 + K,.

Potassium CH,

Acetate. Dimethyl.

Both synthetic methods proceed in an analogous manner, if a mixture of the
iodides of two different alcohol radicals, or the salts of different acids, be em-
ployed : —

CH3
CHjI + CjHjI + Naj = I +2NaI
C3H,
Propyl Methyl.

QHj.COjK + C,H,.COjK = I +2C0, + K,.

C3H,

Propyl Ethyl.

It is known that the hydrocarbons obtained by these different
methods are of similar composition and similar structure. Di-
methyl is identical with ethyl hydride (ethane) ; diethyl with methyl
propyl or butyl hydride (butane). This is evident from a con-
sideration of the structural formulas. Thus, normal butane,
CH3 — CHj — CHj — CHg, may be viewed as butyl hydride,

C2H5 CH,

C4H9H, or as diethyl, | , or propyl methyl,

CH3

Isobutane, CH3 — CH(' , can be regarded as isobutyl hydride,
CHj
CH3 CH3

H.CHj — CH(' or as isopropyl methyl, | , or tri-

^CH,, CH(CH,), ,

methyl methane, CH(CH3)3, etc. Thus, the various syntheses of a
given hydrocarbon may be deduced from its structural formula.

Of other synthetic methods we will yet mention the one employed
in the preparation of quaternary hydrocarbons (p. 40). It consists
in the action of the zinc alkyls upon acetone chloride and bodies
similarly constituted : —

CHov >Cxi3 CHqs /^^s

)CC1, + ZnC = )C( + ZnCl..

CU/ \CH3 CH,/ ^CHj

Acetone Zinc Tetramethyl

Chloride. Methyl. Methane.

The ethanes arise in the dry distillation of wood, turf,. bitumi-
nous shales, h'gnite and bituminous coal, and especially Boghead

PARAFFINS OR ETHANES.

73

and cannel coal, rich in hydrogen ; hence they are also present
in illuminating gas and the light tar oils. Petroleum contains
them already formed. They are, from methane to the highest
hydrocarbon, almost the sole constituents of this compound.

The lowest members, up to butane, are gases, at ordinary temper-
atures, soluble in alcohol and ether. The intermediate members
form colorless liquids of faint, characteristic odor, insoluble in
water, but miscible with alcohol and ether. The higher members,
finally, are crystalline solids (paraffins), soluble in alcohol, more
readily in ether. The specific gravities of the hquid and solid
hydrocarbons increase with the molecular weights, but are always
less than that of water. The boiling points, too, rise with the
molecular weights, and, indeed, the difference for CHj in case of
similar structure of homologues, equals 36°, subsequently, with
higher members it varies from 25°-i3° (see p. 76). The isomer-
ides of normal structure (p. 40) possess the highest boiling points;
the lowest are those of the quaternary hydrocarbons. The general
rule is — the boiling point of isomeric compounds falls with the
accumulation of methyl groups in the molecule.

The paraffins are not capable of saturating any additional affini-
ties ; hence, they are not absorbed by bromine or sulphuric acid,
being in this way readily distinguished and separated from the
unsaturated hydrocarbons. They are slightly reactive and are
very stable, hence, their designation as paraffins (from parutn
affinis). Fuming sulphuric acid and even chromic acid are with-
out much effect upon them in the cold ; when heated, however,
they generally burn directly to carbon dioxide and water. When
acted upon by chlorine and bromine they yield substitution pro-
ducts:—

CH^ + Q\ = CH3CI + HCI,
CHj + 4CI2 = CCI4 + 4HCI.

Other derivatives may be easily obtained by employing these
products.

(i) Methane, CHi (Methyl hydride), is produced in the decay
of organic substances, therefore disengaged in' swamps (marsh
gas) and mines, in which, mixed with air, it forms fire damp.

In certain regions, like Baku in the Caucasus, and the petro-
leum districts of America, it escapes, in great quantities, from
the earth. It is also present, in appreciable amount, in illu-
minating gas. .

The synthesis of methane from CS2 and CCI4 was noticed upon
page 69. It is most conveniently prepared by heating sodium

74 ORGANIC CHEMISTRY.

acetate, in a glass retort, with 2 parts of soda-lime: CHsCOjNa
+ NaOH = CH4 + C03Na2.

Methane is a colorless, odorless gas, compressible under great
pressure and at alow temperature; its critical temperature is — 82°,
and its critical pressure 55 atm. Its density equals 8 (H = i) (or
0.5598, air= i). It is slightly soluble in water, but more readily
in alcohol. It burns with a faintly luminous, yellowish flame, and
forms an explosive mixture with air : —

CH4 + 20j = CO2 + 2H2O.

I vol. 2 vols. I vol. 2 vols.

It is decomposed into carbon and hydrogen by the continued
passage of the electric spark. When mixed with two volumes of
chlorine it explodes in direct sunlight, carbon separating (CH, -|-
2CI2 =: C -\- 4HCI) ; in diffused sunlight the substitution products
CH3CI, CHjClj, CHCl,, and CCU are produced.

(2) Ethane, C^Hs (Ethyl Hydride, Dimethyl), is a colorless and
odorless gas, condensable at 4° and a pressure of 46 atmospheres.
Its formation from C2H5I, (C2H5)2Zn, CH3I and CH3.CO2K cor-
responds to the general methods.

To prepare ethane, decompose zinc ethyl with water. It is obtained more
conveniently by heating acetic anhydride with barium peroxide : —

2(C2H,0)20 + Ba02 = CjHe + [C^Kfi,), Ba + 200,.

The identity of the ethanes prepared by the various methods is ascertained from
their derivatives, and confirmed by their similar heat of combustion {Btrickfe, 14,
SOI)-

Ethane is almost insoluble in water ; alcohol dissolves upwards
of 1.5 vols. Mixed with an equal volume of chlorine it yields
ethyl chloride, C2H5CI, in dispersed sunlight; higher substitution
products arise with excess of chlorine.

(3) Propane, C^Hj, ethyl methyl, occurs dissolved in crude petroleum, and
is most conveniently formed by the action of zinc and hydrochloric acid upon the
two propyl iodides, CjH,!. It is a gas, but becomes a liquid below 17°. Alcohol
dissolves upwards of six volumes of it.

(4) Butanes, C^Hjj (Tetranes). According to the rules of chemical structure,
two isomerides correspond to this formula : —

(i) CHj— CHj — CH, — CH, (2) CH3— CH/

Normal Butane. ^CH

Trimethyl Methane.

1. Normal butane (or diethyl, or propyl methyl, p. 72) occurs in crude petro-
leum, and is obtained synthetically by the action of zinc or sodium upon ethyl
iodide, CjHjI. It condenses below 0° to a liquid, boiling at + 1°.

2. Trimethyl methane or isopropyl methyl, also termed isolDutane, is prepared
from the iodide of tertiary butyl alcohol, (CH3)3CI, by the action of zinc and
hydrochloric acid. It condenses to a liquid at — 17°.

PARAFFINS OR ETHANES. 75

(5) Pentanes, CjHjj. There are three possible isomeridf s : —

(I) CH3 — CH,— CHj — CH2 — CHj (2) CH3 — CHj — Ch/ '

Normal Pentane. ^CH

B. P. 38°. Dimethyl Ethyl Methane.

B. P. 30°.

(3) CH, CH3

X

CH3 CH3

Tetramethyl Methane,
B. P. 10°.

1 . Normal pentane exists in petroleum and the light tar oils of cannel coal, but
has not been obtained by synthesis. It is a liquid, boiling at 37-39°, and having
a specific gravity of 0.626 at 17°.

2. Isopentane is also present in petroleum, and is obtained from the iodide of
the amyl alcohol of fermentation. It is a liquid, boiling at 30° ; specific gravity
= 0.638 at 14°.

3. Tetramethyl methane (quaternary pentane) is made by acting upon the
iodide, (€113)301, of tertiary butyl alcohol, or upon so-called acptone chloride,

^CClj, vpith zinc methyl (comp. p. 71). It is a liquid, boiling at 9.5°, and

solidifying to a white mass at — 20°. The addition of methyl groups constantly
lowers the boiling point, but facilitates the transition to the solid state — raises the
melting point.

(6) Hexanes, CgHj^. Five isomerides are possible : —

(I) CH3— CHj— CHj— CHj— CH^— CH3 (2) CHj— CHj— CHj— CH^

Normal Hexane. Propyl-dimethyl-methane. ^CH ,

Dipropyl, B. P. 71°. Propyl-isopropyl, B. P. 62°.

CH3, .CH3 CH2— CHg

(3) )CH-CH/ (4) CH3-CH(

^' Cn/ ^CH, " \CH,-CH3

Di-isopropyl, B. P. 58°. Diethyl-methyl-methane.

CH3. yCHj — CH3

^^^CH3/''\CH3

Tri-methyl-ethyl-methane, B. P. 43°-48°.

Four of these are known. Normal hexane, occurring in petroleum, may be
obtained artificially by the action of sodium uponjnormal propyl iodide, CH3.
CHj.CHjI; by the distillation of suberic acid withAjarium oxide (p. 71); and
further when nascent hydrogen acts on hexyl iodide, C5H13I (from mannitol).
It boils at 71.5°, and has the specific gravity 0.663 ^t '7°-

(7) Heptanes, C,H,,. Four of the nine possible isomerides are known.
Normal heptane, CH,.— (CH2)5— CH3, is contained in petroleum and the tar

oil from cannel coal. Together with octane it constitutes the chief mgredient
of commercial ligroine (p. 77). It is produced in the distillation of azelaic
acid, CjHijO^, with barium oxide. It boils at 99°. Its specific gravity at
19° ^0.6967.

(8) Octanes, CgHjg. Of the eighteen possible isomerides, two are known.
Normal octane is present in petroleum and is obtained from normal butyl iodide,

76

ORGANIC CHEMISTRY.

C^HjI, by action jof sodium (hence dibutyl), also from sebacylic acid,
CijHjgO^, and from octyl iodide, CgHi,!. It boils at 125°, and its specific
gravity at 0° = 0.718.

The higher homologUes occur in petroleum and tar oils, but cannot be
isolated perfectly pure by fractional distillation. The different isomerides are
obtained according to the methods already indicated. A series of normal
paraffins in pure condition has been prepared by the reduction of the corres-
ponding acids, Cn HsnOj, acetones, Cn H^nO, and alcohols, Cn H211 + =0 (of
normal structure). The reduction of acids to paraffins ensues when the former
are directly heated to 200-250° with concentrated HI and amorphous phos-
phorus; the acetones (ketones) must first be converted into the chlorides,
Cn HanClj, through the agency of PCI5, and the alcohols also into chlorides,
Cn Han + 1 CI, and alkylens, Cn Hjn. The higher paraffins can be readily pre-
pared by the action of sodium upon the methyl iodides. In this way the following
normal paraffins hare been obtained (F. KraSt, BericAie, 15, 1687 and 1711;

17, 2218).

Melting Point,

Nonane C,

Decane C,

H20
nH,

Undecane CnHj^

Dodecane CjjHjg

Tridecane C13H2J

Tetradecane ^14^30

Pentadecane C^H^j

Hexdecane CjjHj^

Heptdecane Ci,Hgg

Octdecane CjjHjg

Nondecane CjoH

Eicosane C

Heneicosane C_

Docosane C22H4

Tricosane CjjH^

Tetracosane Cj^Hj

Heptacosane Cj^H^

Hentriacontane CjjHg

Dotriacontane CgjHg

Pentatriacontane C,,H,

40
20"42
H. ,

-51°
— 32°
—26.5°
—12°
—6.2°

+4-5°
-1-10°
+18°

+22.5°
+ 28°
+32°
+36.7°
+ 4.0.4°

+44.4°

+47-7°
+51.1°

+59-5°
+68.1°
+70.0°
+74-7°

B.P.

149-5°
173°
194.5°
214°

234°

252.5°

270.5°

287.5°

303°

317°

L33o°

"205°
215°
224.5°
234°
243°
270°
302°
310°

1331°

Sp. Gr.*

0-7330
0.7456

0.774s
0.773
0-775
0.775

0.775
0.77s
0.776
0.776
0.777
0.777
0.778
0.778
0.778
0.778

0.779
0.780
0.781
0.781

The higher normal paraffins, from hexdecane, C^^H^^, forward, are solids at
ordinary temperatures, and crystallize readily from alcohol or ether. It is very
remarkable that the specific gravities of the higher members are almost equal at
their melting points, consequently the molecular volumes are nearly proportional
to the molecular weights {Berichie, 15, 1719). Compare Ann., 223, 268.

The highest paraffin that has yet been obtained is Hexacontane, Cj^Hj^j, or
JMmyruyl. It is produced when potassium or sodium acts upon myricyl iodide,
CjjHgil (from myricyl alcohol). It dissolves with difficulty in alcohol and
ether, and separates in the form of a white powder from benzene and chloroform.
It melts at 102°, and when distilled, even in vacuo, sustains a partial decom-
position [Ber., 22, 502).

The higher members of this series are contained in petroleum
and the tar oils prodiiced in the distillation of turf, lignite and

* The specific gravities correspond to the temperatures at which the bodies melt (for nonane
and decane at 0°).

PARAFFINS OR ETHANES. 77

bituminous coal. To isolate them in a pure condition, crude petro-
leum or the light tar oils are treated with concentrated sulphuric
acid, which dissolves the non-saturated hydrocarbons, e.g., CnHjn,
and those of the benzene series (in tar oil) and destroys other
organic substances. The separated oil is further treated with fuming
nitric acid and sodium hydroxide, washed with water, dried, and
fractionated over metallic sodium. In this way a whole series of
hydrocarbons is obtained. Two series of hydrocarbons have been
isolated from that fraction of American petroleum that boils from
o°-i30°. The members of the first series possess normal struc-
ture : —

C4H1I,

0°

C5H12

38°

C5H1,

30°

^6^14

71°

^6^14

61°

C»Hi5

99°

C,Hj5

91°

CjHis

125°

CgHis

118°

The members, C9H20 to CieHj, (boiling at 270°), separated from
the higher fractions, have not been obtained perfectly pure.

Petroleum or rock-oil (naphtha) was probably produced by the
dry distillation of coal beds, caused by the earth's heat, or more
probably by that of the fatty constituents of fossil animals (see
Ehgler, Ber., 21, 1816). It occurs widely distributed in the upper
strata of the earth — in Italy, Hungary, Gallicia, and in very con-
siderable quantities in the Crimea and the Caucasus (on the shore
of the Caspian). Its occurrence in Alsace and Hanover is not very
extensive. It is obtained in remarkably large quantities in North
America (in Pennsylvania and Canada) by boring. In a crude
condition, it is a thick, oily liquid, of brownish color, with greenish
lustre. Its more volatile constituents are lost upon exposure to the
air ; it then thickens and eventually passes into asphaltum. The
greatest differences prevail in the various kinds of petroleum ; it is
only of late years that their thorough study has been commenced.

American petroleum consists almost exclusively of normal paraf-
fins ; yet minute quantities of some of the benzene hydrocarbons
(cumene and mesitylene) appear to be present. In a crude form it
has a specific gravity of 0.8-0.92, and distils over from 30-360°
and beyond this. Various products, of technical value, have been
obtained from it by fractional distillation : Petroleum ether, specific
gravity 0.665-0.67, distilling about 50-60°, consists of pentane and
hexane ; petroleum benzine, not to be confounded with the benzene
of coal tar, has a specific gravity of 0.68-0.72, distils at 70-90°,
and is composed of hexane and heptane ; ligroine, boiling from
90°-! 20°, consists principally of heptane and octane; refined
petroleum, called also kerosene, boils from 150-300° and has a
specific gravity of 0.78-0.82. The portions boiling at higher tem-

78 ORGANIC CHEMISTRY.

peratures are applied as lubricants ; small amounts of vaseline and
paraffins (see below) are obtained from them.

Caucasian petroleum (from Baku) ha.s a higher specific gravity than the Ameri-
can; it contains far less of the light volatile constituents, and distils about 150°.
Upwards of 10 per cent, benzene hydrocarbons (CjHg to cymene Cj oH, 4) may be
extracted by shaking it with concentrated sulphuric acid ; and in addition less
saturated hydrocarbons, C„ H2o_g, etc., {Ber., 19, Ref. 672). These latter are also
present in the German oils (Naphthenes, Ber., 20, 605). That portion of the
Caucasian petroleum insoluble in sulphuric acid consists almost exclusively of
CnHjn hydrocarbons, of peculiar constitution. They are designated naphthenes,
octonaphthene, CjHjg, nononaphthene, CgHj , (^^r., 16, 1873; 18, Ref. 186).
At present they are considered identical with the benzene hexa-hydrides (octonapn-
theiie is xylene-hexahydride, nononaphthene is mesitylene hexahydride {Ber., 20,
1850, Ref. 570). From its composilion, Gallician petroleum occupies a position
intermediate between the American and that from Baku (Annalen, 220, 188).

German petroleum also contains benzene hydrocarbons (extracted by sulphuric
acid), but consists chiefly of the saturated hydrocarbons and naphthenes (Kraemer,
Ber., 20, S45)- The so-called petrolic acids are present in all varieties of petro-
leum (see oleic acids).

Products similar to those afforded by American petroleum, are
yielded by the tar resulting from the dry distillation of cannel coal
(in Scotland) and a variety of coal found in Saxony. The com-
bustible oils obtained from the latter usually bear the names, photo-
gene and solar oil. Large quantities of solid paraffins are also
present in these tar oils.

'&y paraffins, we ordinarily understand the high-boiling (beyond
300°) solid hydrocarbons, arising from the distillation of the tar
obtained from turf, lignite and bituminous shales. They are more
abundant in the petroleum from Baku than in that from America.
Mineral wax, ozokerite (in Gallicia and Roumania) and neftigil (in
Baku), are examples existing in a free solid condition. For their
purification, the crude paraffins are treated with concentrated sul-
phuric acid, to destroy the resinous constituents, and theii re-distilled.
Ozokerite that has been directly bleached, without distillation, bears
the name ceresine, and is used as a substitute for beeswax. Paraffins
that liquefy readily and fuse between 30-40°, are known as vaselines;
they find application as salves.

When pure, the paraffins form a white, translucent, leafy, crys-
talline mass, soluble in ether and hot alcohol. They melt between
45° and 70°, and are essentially a mixture of hydrocarbons boiling
above 300°, but appear to contain also those of the formula C^ Hja.
Chemically, paraffin is extremely stable, and is not attacked by
fuming nitric acid. Substitution products are formed when chlo-
rine acts upon paraffin in a molten state.

The hydrocarbons, C^^H^g, Cj^Hgo and C2gH5 j, were isolated from a com-
mercial paraffin, melting at 52-54°, by fractional distillation and crystallization.

ALKYLENS OR OLEFINES. ' yr)

They have been proved identical with the normal paraiifins prepared artificially
(see p. 76). r r r J

Another paraffin, known as scaly paraffin, has been resolved into hydrocarbons
ranging from heptdecane, C^Hj^, to C^jH^, (tricosane), Ber., 21, 2256).

Caucasian ozokerite consists mainly of one hydrocarbon (called lekene) melting
at 79°, and having the composition C„H2„ + ^ or C^H^ {Berichte, 16, 1548).

(2) UNSATURATED HYDROCARBONS C^H^^.

ALKYLENS OR OLEFINES.

CjH^ Ethylene. C^Hi^ Hexylene.

C3H, Propylene. CjHj^ Heptylene.

C^Hj Butylene. CjHig Cetene.

C^H^o Amylene. Ca^Hgo Melene.

The hydrocarbons of this series contain two hydrogen atoms less
than the first series. In their general structure, two adjacent car-
bon atoms are united by two affinity units each— by double linking
(see p. 42) :

CHj = CHj CH3— CH = CH^

Ethylene. Propylene.

Three structural cases are possible for the third member: —
(I) CH,-CH,— CH = CH, (2) CH3-CH = CH-CH3

Butylene. Isobutylene.

(3) CH, = C/

^CHj

Pseudobutylene.

Five isomerides of the formula C5H10 are possible.* The most
important general methods for the preparation of these hydro-
carbons are : —

(i) Distil the monohydric alcohols, C„H2„ + iOH, with dehy-
drating agents, e. g., sulphuric acid, chloride of zinc, and phos-
phorus or boron trioxide. These remove one molecule of water : —

C^HjO — HjO = CjHj

Alcohol. Ethylene.

The secondary and tertiary alcohols decompose with special readiness. The
higher alcohols, not volatile without decomposition, suffer the above change when
heat is applied to them; thus cetene, CjjHjj, is formed on distilling cetyl alcohol,

* The ring-shaped atomic linkings, exemplified in trimethylene, CjHg, and
tetramethylene, CjHg (see p. 42), are not included here. Their properties are
different from those of the alkylens, and they at the same time form a transition to
the closed ring of benzene. For this reason they will be considered after the
fatty bodies.

So ORGANIC CHEMISTRY.

When sulphuric acid acts upon the alcohols, acid esters of sulphuric acid (the
so-called acid ethereal salts — see these) appear as intermediate products. When
heated these break up into sulphuric acid and Cn Hjn hydrocarbons : —

SO / = SO,H, + C,H,

NQH Ethylene.

Ethylsulphuric
Acid.

The higher olefines may be obtained from the corresponding
alcohols by distilling the esters they form with the fatty acids.
The products are an olefine and an acid {Berichte, i6, 3018) : —

CigHjiO . O . CijHjj =Ci5H3jO . OH + Cj^H^i
Dodecyl Ether of Palmitic Acid. Dodecylene.

Palmitic Acid.

(2) The halogen derivatives, readily formed from the alcohols, are
digested with alcoholic sodium or potassium hydroxide : —

I +KOH=|| +KBr + HjO.
CHjBr CHj

Ethyl Bromide. Ethylene.

In this reaction also, the haloid (especially the iodides) derivatives corresponding
to the secondary and tertiary alcohols break up very readily. Heating with lead
oxide effects the same result {Berichte, 11, 414).

(3) Electrolyze the alkali salt,of a dibasic acid (see p. 71) :■:—

CHj— COjK CH,

I =11 +2C0, + K,.

CHj— COjK CHj

Potassium
Succinate.

This reaction is perfectly analogous to the formation of the dialkyls
from the monobasic fatty acids (see p. 72).

(4) The olefines also result, on heating some of the dihalogen
compounds, CnHj^Xj, with sodium: —

CH,C1 CH,

+ Na, = 2NaCI -f 11 .

::h,ci cHj

Ethylene Chloride. Ethylene.

ii

The olefines can be prepared synthetically according to methods
similar to those employed with the normal hydrocarbons (see p. 69).

The formation of higher alkylens in the action of lower members with tertiary
alcohols or alkyl-iodides is noteworthy. Thus, from tertiary butyl alcohol and
isobutylene, with the assistance of zinc chloride or sulphuric acid, we get
isodibutylene, {Annalen, 189, 65) : —

(CH3),C . OH + CH, : C(CH3), = (CH,),C . CH : CCCHg), + H^O.

Isodibutylene.

ALKYLENS OR OLEFINES. 8l

Tetramethyl ethylene {Berichte, i6, 398) is singularly produced on heating ^-isoamy-
lene (see p. 85) with methyl iodide and lead oxide : —

(CH3),C : CH . CH3 + CH3I = (CH3),C : CCCHg), + HI.

In the dry distillation of many complicated carbon compounds,
the defines are produced along with the normal paraffins, hence
their presence in illuminating gas and in tar oils.

As far as physical properties are concerned the defines resemble
the normal hydrocarbons ; the lower members are gases^ the inter-
mediate ethereal liquids, while the higher (from CieHsj up) are
solids. Generally their boiling points are a few degrees higher than
those of the corresponding paraffins.

Being unsaturated, they can unite directly with two univalent
atoms or groups ; then the double binding becomes single.
With chlorine, bromine and iodine they combine directly :
CH2 CIj[2Br

II -\- Br^ = 11^ , forming oily liquids ; hence the designation

Cxij CiigBr

of ethylene as olefiant gas, and that of olefines for the entire
series. The liquid olefines react very energetically with bromine ;
on this account they should be cooled and diluted with ether.

Concentrated sulphuric acid absorbs them, forming ethereal
salts : —

O.C^H,

Very often the absorption takes place only at high temperatures.

They combine, too, directly with HCl, HBr and with especial
readiness with HI.

They yield so-called chlorhydrins with aqueous hypochlorous

"'acid : —

CHj CHjCl

II -fC10H=f

CHj tejOH.

Nascent hydrogen (zinc and hydrochloric acid, or sodium amal-
gam) converts the olefines into the saturated hydrocarbons:
CjHi -j- Hj = C3H5.

Concentrated hydriodic acid effects the same if aided by heat,
and, especially, when phosphorus is present. The iodide formed
at first is reduced by a second molecule of HI : —

C.H, +HI = CjH5land
C2HJ + HI = QH,+I,.

82 ORGANIC CHEMISTRY.

Oxidation of Okfines. It has been generally supposed that when
the olefines were exposed to the action of oxidizing agents {e.g.,
potassium permanganate, and chromic acid), they were split up
at the point of their double union {Ann., 197, 225). The most
recent research, however, has demonstrated that two hydroxyl
groups always result, thus giving rise to the formation of dihydric
alcohols (see these) (Wagner, Ber., 21, 1230 and 3359) : —

CHj.OH

CHj.OH.

The unsaturated alcohols and acids are similarly oxidized. Potassium per-
manganate is without action upon trimethylene.

Polymerization of Olefines. When acted upon by dilute hydro-
chloric acid, zinc chloride, boron fluoride and other substances,
many olefines sustain, even at ordinary temperatures, a polymeri-
zation, in consequence of the union of several molecules. Thus
there result from isoamylene, CsHjo : di-isoamylene, CjoHj,, ; tri-
isoamylene, QsHjo, etc., etc. Butylene and propylene behave in
the same way. Ethylene, on the other hand, is neither condensed
by sulphuric acid nor by boron fluoride. The polymerides act like
unsaturated compounds, and are capable of binding two affinities.

The nature of the binding of the carbon atoms in polymerization is, in all
probability, influenced by the different structure of the alkylens. The manner of
formation and structure of the isodibutylene produced from isobutylene corres-
pond to the formulas : —

(CH3),C : CH, + CH, : C(CH,), = (CH3)3C.CH : qCH,),.
2 Mols. Isobutylene. Isodibutylene.

Tertiary butyl alcohol very probably figures as an intermediate product, and
afterwards unites with a second molecule of isobutylene, and condenses to iso-
dibutylene.

Although ethylene suffers no alteration, yet its substitution products polymerize
very readily.

Methylene, CHj, the first member of the series C„ Han, does not exist. In
all the reactions in which it might be expected to occur, for instance, when copper
acts on methylene iodide, CHj Ij, we obtain only polymerides; ethylene, CjHj,
propylene, CjHj, etc.

(i) Ethylene, C2H4 (olefiant gas), is formed in the dry distillation
of many organic substances, and is, therefore, present in illuminating
gas (6 per cent.). It is best prepared by the action of sulphuric
acid upon ethyl alcohol.

A mixture of I vol. 80 per cent, alcohol and 6 vols, sulphuric acid is permitted
to stand for awhile, then heated, in a capacious vessel, upon a sand bath. The
foaming may be prevented by the addition of sand. The liberated gas is conducted
through a vessel containing potassium hydroxide, to remove COj and SOj, and,
finally, collected over water [Anna/en, 192, 244).

ALKYLENS OR OLEFINES. 83

Ethylene is a colorless gas, with a peculiar, sweetish odor. Its
sp. gr. equals 14 (H = i). Water dissolves but small quantities
of it, while alcohol and ether absorb about 2 volumes. It is lique-
fied at 0°, and a pressure of 42 atmospheres. At ordinary pressure
it boils at — 105°, and is suitable for the production of very low
temperatures. It burns with a bright, luminous flame, decomposing
into CHj and C. In chlorine gas the flame is very smoky ; a mix-
ture of ethylene and chlorine burns away slowly when ignited. It
forms a very explosive mixture with oxygen (3 volumes).

When in alcoholic solution ethylene combines readily with
chlorine, bromine and iodine. Fuming hydriodic acid absorbs
it with formation of C2H5I. Aided by platinum black it will
combme with H^ at ordinary temperatures, yielding CjHe. At the
ordinary temperature it combines with sulphuric acid only after
continued shaking; the absorption is, however, rapid and com-
plete at 160-174°. By boiling the resulting ethylsulphuric acid
with water we can get alcohol. Potassium permanganate oxidizes
ethylene first to ethylene glycol, CJi^OH), (p. 82), and then to
oxalic and formic acids.

(2) Propylene, CsHe = CH3.CH : CH^, is obtained from many
organic substances, e. g., amyl alcohol, when their vapors are
conducted through red-hot tubes. Propyl and isopropyl iodide
are converted into it when boiled with alcoholic potash : —

CjH,! + KOH = C3H5 -f KI + H,0.

The same end is achieved by the action of nascent hydrogen
(zinc and hydrochloric acid) or hydriodic acid upon allyl iodide : —

C3H5l-(-HI = C3H,-|-I,.

Preparation. — 1. Digest a mixture of 80 gr. isopropyl iodide, 50 gr., 95 per
cent, alcohol, and Jo gr. KOH upon a water bath ; at 40-50° a regular stream of
propylene escapes. 2. A solution of allyl iodide in glacial acetic acid, or, better,
one in alcohol, is allowed to drop upon granulated zinc {Ber., 6, 1550).

Propylene is a gas, liquefiable under great pressure. It combines
directly with the halogens and their hydrides. Concentrated
H2SO4 dissolves it with formation of isopropyl sulphuric acid and
polymeric propylenes (C3H6)n . It dissolves in concentrated HI,
yielding isopropyl iodide: —

CH, — CH = CH2 -f HI = CH3 _ CHI — CH3.

Trimethylene, CjHg, isomeric with propylene, is obtained from trimethylene
bromide (see p. 102), by aid of sodium, Unlike propylene, it unites with difficulty
with bromine to trimethylene brorpide, and with HI to normal propyl iodide. It
appears to contain a closed carbon chain (see p. 42), and, with its derivatives, is
considered after the fatty bodies.

84 ORGANIC CHEMISTRY.

(3) Butylenes, C^Hg. — Theoretically, three isomerides are possible: —

CH3 . CHj . CH : CHj CH3 . CH : CH . CH3 (CHgj^C : CH^.
a-Butylene /3-Butylene Isobutylene.

(1) a-ButyUne (norinal Butylene) is formed from normal butyl iodide,
CH3 . CH2 . CH2 . CH^I, by aid of alcoholic potash; and also from brom-
ethylene and zinc-ethyl : 2CH2 : CHBr + (C2H5)2Zn = 2CH2 : CH . C^Hj
+ ZnBrj. In the cold it condenses to a liquid, boiling at — 5°. With HI,
it forms secondary butyl iodide, CHj CHj . CHI . CHg. Its bromide,
C^HjBr^, boils at 66°.

(2) ^-Butylene (pseudo-butylene) results from secondary butyl iodide (see
above) and alcoholic potash or mercuric cyanide; also (together with isobutylene)
from isobutyl alcohol, in which case there occurs a molecular transposition. It
boils at ■\- 1° and solidifies on cooling. It yields secondary butyl iodide with HI.
Its bromide, C^HjBr^, boils at 159°, and is changed by alcoholic potash to crctony-
lene, CH3 . C : C . CH3 (p. 89). See Ann., 250, 252, for the geometrical isomerides
of pseudobutylene.

(3) Isobutylene is obtained from isobutyl iodide, (CHj)^ CH . CHjI, and ter-
tiary butyl iodide, (CH3)2C1 . CH3, when alcoholic potash acts upon them;
further from isobutyl alcohol, (CH3)2 . CH . CHjOH, when heated with zinc
chloride or sulphuric acid. Pseudo-butylene appears at the same time (Berichte,
13, 2395 and 2404, 16, 2284). For a method of separating these two butylenes, con-
sult Ber., 19, Ref. 554. It boils at — 6° and dissolves in sulphuric acid (diluted
one half with water), forming butyl-sulphuric acid. The latter yields trimelhyl
carbinol, when boiled with water. Concentrated HI absorbs isobutylene with
formation of tertiary butyl iodide. Its bromide boils at 149°. Potassium perman-
ganate oxidizes isobutylene to its glycol, (CH3)2 . C(OH) . CH2(GH) (p. 82).

When isobutylene is digested with H2SO4 and HjO (equal volumes) it becomes
isodibutylene, (CH3)3C . CH : C(CH3)2, boiling at 130° (see p. 81).

(4) Amylenes, CsHj^. — Five isomerides are theoretically possible : —

(i) CH3 . CHj . CHj . CH : CHj. (2) CH, . CHj . CH : CH . CH3.
a-Amylene, Normal Propyl Ethylene. )3-Amylene, Ethyl Methyl Ethylene.

CH3. CH3.

(3) )CH . CH : CH2 (4) )C : CH . CH3.

CH3/ CH3/

a-Isoamylene, Isopropyl Ethylene. /S-Isoamylene, Trimethyl Ethylene.

CH3

(5) >C : CH2.

•y-Amylene, Unsym. Ethyl Methylethylene.

(1) a-Amylene, C3H, . CH : CHj (normal amylene, propylethylene), has not
yet been prepared in a pure condition; it appears to be that part of ordinary
amylene (see below) which is insoluble in sulphuric acid, boils about 37° and is
oxidized by a KMn04 solution chiefly to butyric and formic acids {Amtalen,
197, 253). It unites with HI to the iodide, C3H, . CHI . CH,, boiling at 144°.

(2) ^Amylene, CjHj . CH : CH . CH3 (sym. ethylmethyl-ethylene), is
produced from the iodide of diethylcarbinol, CjHj . CHI . C2H5, boiling at
145°. The boiling point of /3-amylene is 36°; with HI it yields the same
iodide as o-amylene. Its*bromide, C5Hj„Br2, boils at 178°.

(3) a-Isoamylene, (CH3)2CH.CH:CH2 (isopropyl ethylene), is formed together
with y-amylene, from the iodide of the amyl ajcohol of fermentation (see this), by
the action of alcoholic potash {Annalen, 190, 351). A mixture of these two

ALKYLENS OR OLEFINES. 85

amylenes results, and boils at 23-27°. On shaking with cold H^SO^ (diluted one-
half with water) the y-variety dissolves, leaving a-isoamylene unaltered (about 60
per cent, of the mixture). Similarly, by action of HI (or HBr) upon the mixture
at — 20°, y-amylene is changed to the iodide, while a-amylene is not affected.
It yields propyl-ethylene glycol when oxidized with potassium permanganate.
Isoamylene boils at 2I.1°-2I.3°. It does not unite in the cold (below 0°) with
H2SO4, HI, or HBr. At ordinary temperatures it combines gradually with
HI, 'HBr, and H CI, yielding derivatives of methyl isopropyl carbinol, (CHj)^.
CH.CHX. CH3.

(4) P- Isoamylene, (CH3)2.C:CH.CHj (trimethyl ethylene) produced from
the iodides of methyl isopropyl carbinol, (CH3)2CH.CHI.CH3, and dimethyl-
ethyl carbinol, (CH3)2.CI.CH2.CH3, boils at 36—38°. At ordinary temperatures
it reunites with HI to the iodide, (CHj'Jj.CI.CHg.CHg. It combines readily,
in the cold, with sulphuric acid to the sulphuric ether, and the latter, when boiled
with water, affords dimethyl-ethyl carbinol, (CH3)2.C^OH).CH2CH3.

/5-Isoamylene is the chief ingredient of the ordinary amylene
obtained from fermentation amyl alcohol by distillation with zinc
chloride. (See Annalen, 190, 332.) The product, boiling about
25-40°, is a mixture of ^-isoamylene (50 per cent.) with pentane
(boiling about 29°) and probably contains, in addition, ^--amylene
and also a-amylene. On shaking crude amylene in the cold
( — 20°) with sulphuric acid, diluted with J^-i vol. of HjO, the
^-isoamylene dissolves (also any ^'-amylene that may be present) to
amyl-sulphate, which yields dimethyl-ethyl carbinol, (CHa)^.
C(OH).CH2.CH3. The chief constituents of the undissolved oil
are pentane and a-amylene, which are oxidized by KMnO^ to
butyric and formic acids (see above).

On shaking ordinary crude amylene with H^SO^ (diluted with ^ vol. water),
without cooling, polymeric amylenes are produced: diamylene, Ci^Hj^, boiling
at 156°, triamylene, CjjHgo, boiling at 240-250°, and tetramylene, boiling about
360°. All these are oily liquids, which combine with bromine.
CH3.

(5) y-Amylene, ^Q:CR^, (unsym. methyl-ethyl ethylene), is contained

C2H5/
(40 per cent.) in crude amylene, obtained from the iodide of fermentation amyl
alcohol (see above 3), hence, very probably also present in ordinary amylene. It

CHg.^

very likely comes from the>ctive alcohol, CH.CHj.OH, present in the

fermentation alcohol, although itself not active. It cannot be isolated because of its
very ready union with H2SO4 and HI, even in the cold. Both the sulphuric acid
ethf r from it and the iodide yield tertiary amyl alcohol. The iodide of acUve amyl
alcohol furnishes an amylene boiling at 31° (Le Bel). This is probably pure

CH3,
7-amylene. It gives the chloride, pCCl.CHj, with HCl. This boils ^t

87°, and decomposes with alcoholic potash into /3-isoamylene.

Various higher olefines have been prepared from the correspond-
ing alcohols'. The highest can be made by the distillation of the

86 ORGANIC CHEMISTRY.

esters derived from the alcohols and the higher fatty acids (p. 80).
In this way the following olefines of normal structure have been
prepared :

Melting Point. B. P. at is mm. Sp. Gr.

Dodecylene CijHj^ — 3i-5° 96° 0.7954

Tetfadecylene Ci^H^g —12° 127° 0.7936

Hexadecylene CigHja +4° 154° 0-79I7

Octodecylene CigHjj +18° 179° 0.79IO

Hexadecylene, CieHsj, is sometimes called cetene; it was first ob-
tained from cetyl alcohol, and at ordinary temperatures boils about
240°. Cerotene, from Chinese wax, melts at 58°, while melene,
CsoHgo, from ordinary wax, melts at 62°-

(3) HYDROCARBONS C„H2„_2.
ACETYLENE SERIES.

CjHj Acetylene.

CjHg Valerylene.

CjH^ Allylene.

CgHjj Hexoylene.

C^H-g Crotonylene.

The above hydrocarbons, differing from the normal C^H.^^ + j by
four atoms of hydrogen, may be based upon two structurally differ-
ent but possible formulas. In one case we assume a triple union of
two neighboring carbon atoms —

CH=CH CH3— C^CH

Acetylene. Allylene.

while in the second a double union occurs twice —

CH^ = C = CH^ CHj = CH— CH^— CHj— CH = CHj,.

Isomeric Allylene. Diallyl.

This structural difference is abundantly manifest in the varying
chemical behavior, since only members of the first class (having
the group =CH) that can be regarded as true acetylenes, possess the
power of entering into combination with copper and silver, thereby
yielding derivatives in which the H of the group sCH is replaced
by metals.

These compounds result from the action of acetylene upon ammoniacal silver
nitrate and cupric chloride solutions (p. 87). The silver derivatives are obtained
without difficulty by using an alcoholic solution of silver nitrate {Ber., 21J Ref
609).

Diolefines, such as diallyl (see above), dp not form copper and silver compounds,
but produce precipitates with mercury sulphate and chloride in aqueous solutiori
{Ber., 21, Ref. 185 and 717, and allylene, p. 89).

ACETYLENK SERIES. 87

The hydrocarbons of this series are produced according to the
same methods as those of the ethylene series. They are formed on
heating the haloids, C„Hj„_iX (corresponding to the alcohols of
the allyl series) and CoHa^Xj, with alcoholic potash ; in the latter
case the reaction proceeds in two phases —

CHjBr CHBr

I + KOH = II + KBr + H,0
CHjBr CHj

and CHBr CH

II + KOH = III + KBr + H„0.
CHj CH

If the heating with alcoholic potash be too violent the acetylene which has
formed frequently sustains a transposition ; thus, ethyl acetylene, CjHj.C^CH,
yields dimethyl acetylene, CHj. C^C. CHj, and propyl acetylene, C3H,. C^CH,
furnishes ethyl methyl acetylene, C2H5.C^C. CH,, etc. {Ber., 20, Ref. 781).

The reverse transposition sometimes occurs on heating with metallic sodium :
ethyl methyl acetylene passes into propyl acetylene, and dimethyl allene, (CHj)^
C^=C=:CH2, yields isopropyl acetylene, etc. {^Ber., 21, Ref. 177).

Acetylenes also arise in the electrolysis of unsaturated dibasic
acids (compare p. 80).

CH.CO.H CH
II = III + 2CO, + H,.

CH.COjH CH

Fumaric Acid. Acetylene.

As unsaturated compounds of second degree, the hydrocarbons
C„H2„_2 are capable of adding to themselves four affinity units.
Hence they unite with one and two molecules of the halogens and
their hydrides. Thus acetylene forms CjHjBrj and CjHjBr^. They
are absorbed by concentrated sulphuric acid with the formation of
sulphuric ethers ; condensation occurs at the same time. Nascent
hydrogen converts them into the hydrocarbons CoHj^ and

In the presence of HgBr, and other salts of mercury, the acetylenes can unite
with water. In this way we get from acetylene, aldehyde, C^H^O, from allylene,
C3H4, acetone, CsHjO, from valerylene, CjHg, a ketone, C5H10O {Benchte, 14,
1542 and 17, 28). Very often moderately dilute sulphuric acid will act in the
same way (see Allylene).

A characteristic of the true acetylenes is their power to yield
solid crystalline compounds by the action of ammoniacal splutions
of silver and copper salts. Hydrochloric acid will again liberate
the acetylenes from these salts. This behavior affords a very con-
venient method for separating the acetylenes from other gases, as
well as obtaining them in a pure condition.

88 ORGANIC CHEMISTRY.

Like the alkylens (p. 82) the acetylenes condense, and in this manner we
very frequently obtain bodies that belong to the benzene series. At a red heat
benzene, CjH 5, is obtained from acetylene, CjHj ; mesityleue, CjHi, (trimethyl-
benzene, C„H, (CHj),), from allylene, C^H^, by the action of sulphuric acid, and
hexamethyl benzene, CuHig (see p. 89), from crotonylene, C^H^.

Acetylene, C2H2, is formed when many carbon compounds, like
alcohol, ether, marsh gas, methylene, etc., are exposed to intense
heat (their vapors conducted through tubes heated to redness).
Hence it is present in illuminating gas, to which it imparts a
peculiar odor. Its direct synthesis from carbon and hydrogen is
described on p. 70 ; acetylene results, too, in the decomposition of
calcium carbide by water. Its formation in the electrolysis of the
alkali salts of fumaric and maleic acids is significant : —

C2H2(C02H), = CjHj + 2CO2 + H,.

It is produced when silver, copper or zinc dust acts upon iodoform.

Preparation. — I. Ethylene bromide, CjHjBrj, is heated with two parts of
KOH and strong alcohol, in a flask provided with an upright condenser. The
escaping gas is conducted through an ammoniacal silver solution, the precipitate
washed with water and decomposed by hydrochloric acid {Annalen, igi, 368).
2. Let the flame of a Bunsen burner strike back, i. e., bum within the tube, and
then aspirate the gases through a silver solution (Berthelot's apparatus).

Acetylene is a gas of peculiar, penetrating odor, and may be
liquefied at -|- 1° and under a pressure of 48 atmospheres. It is
slightly soluble in water ; more readily in alcohol and ether. It
burns with a very smoky flame. The color of the copper compound,
CjHCu. CuOH, is red, while that of the silver derivative, CjHAg. Ag
OH, is white ; their composition is not definitely established. ^Vhen '
heated, both explode very violently. When acetylene is conducted
through ammoniacal silver chloride, a white, curdy precipitate,
CjHAg. AgCl, is thrown out of solution. Sodium heated in acety-
lene gas disengages hydrogen, and we obtain the compounds CzHNa
and QNa,.

Nascent hydrogen (zinc and ammonia) converts acetylene into
C2H4 and C^Hj ; and when hydrogen and acetylene are passed over
platinum black, CjHj, is formed.

Acetylene reacts very energetically with chlorine gas. It forms a crystalline
compound with SbClj, but heat changes this to dichlor-ethylene, CHCI : CHCl
and SbClj. With bromine it forms CjHjBrj and CjHjBr^.

MonochloT-acetylene, CjHCl, obtained from dichloracrylic acid, is an explo-
sive gas.

ACETYLENE SERIES. 89

Monobrom-acetylene, CjHBr, obtained by boiling acetylene dibromide with
alcoholic potash, is a gas that inflames in contact with air. Below 0° it condenses
to a liquid, which on exposure to the light poljrmerizes to a yellow powder. The
latter contains symmetrical tri-brom-benzene, CjH.Brj.

Mono-iodo-acetylene, CjHI, results on boiling iodoprdpargylate of barium
with water. It is an oil with a very disagreeable odor. It solidifies on cooling.
When preserved it polymerizes to tri-iodo-benzene, C5H3I3 [Ber., 18, 2274).

Di-iodo-tacetylene, C^Ij, results from the action of iodine upon the silver
compound of acetylene. It melts at 78°. It is very readily decomposed when
exposed 10 a higher heat. In the light it polymerizes to hexa-iodo-benzene, Cjlj.

AUylene, C3H,= CH3— C=CH. This is produced by the
action of alcoholic potash upon monochlor-propylene, CHs.
CCl : CHj, and by heating dichloracetone chloride, CHj.CClj.
CHClj, with sodium ; further, in the electrolysis of the alkali salts
of mesaconic and citraconic acids. It is very similar to acetylene.
Its copper compound is siskin green in color ; the silver derivative,
CaHjAg, -is white. AUylene forms the compound (C3H3)2Hg with
mercuric oxide. This crystallizes from alcohol in brilliant needles ;
acids decompose it into allylene and a mercury salt. With bromine
we get the liquid bromides, CsHjBrj and CsHiBri ; and with two
molecules of the halogen hydrides the compounds CH3.CX2.CH3.

Allylene is soluble in concentrated sulphuric acid- A large
quantity of acetone is produced by diluting this solution with
water ; but on distilling it the allylene condenses to mesitylene :
3C3H4 = CgHij, a benzene derivative. In the presence of mercury
salts, allylene combines with water to form acetone (see p. 87).

Isomeric Allylene, CHj:C:CHj. This does not unite with CQpper and silver.
It is produced by the electrolysis of potassium itaconate ; by the action of sodium
upon dichlor-propylene, €311^013 (from dichlorhydrin, see glycerol), or of zinc
dust and alcohol upon dibrom-propylene, CjH^Brj (from tribromhydrin) {Ber.,
21, Ref. 717). It forms precipitates in aqueous solutions of mercuric sulphate or
chloride (p. 86). Sulphuric acid and water coiivert it into acetone, and when,
heated with sodium to 100° it passes into allylene. With brpnune it forms a tetra-
bromide, CgH^Bfj, crystallizing in leaflets aud melting at 195°.

Crotonylene, C^Hj, Valerylene, CjHj, Hexoylenef, CgHj„, or Butine, Pentine
Hexine, etc., are the higher members of the series Cn H2o_ j.

Crotpnylene.CHj.C ■ C.CHj — dimethyl acetylene {Ann., 250, 252), is a strong
smelling liquid obtained from the bromide of pseudo-butylene, CH3.CH:CH.CH3,
by the action of alcoholic potash. Its boiling point is 180°. When it is shaken
with sulphuric acid (diluted ^ with water), it is converted into solid hexamethyl
benzene, C^iCtl^)^, melting at 164° :—

3C4H5 =CijHij = C(i(CH3)5.

Diallyl, CH^iCH.CHj.CHj.CHiCHj, is produced when silver or sodium acts
upon allyl iodide (see p. 98), and by distilling allyl mercury iodide, CjHjHgl,
with potassium cyanide. It boils at 59°, and when oxidized with KM.nO^ yields
two isomeric diglycols, C^^w (OH)^ {Ber., 21, 3344). It forms two tetrabromides,
CjHijBr^, the crystalline melting at 63°, and the other a liquid {Ber., 22, 2497).
As it does not Oontaiij the group =CH, it forms no metal derivatives. Higher
8

go ORGANIC CHEMISTRY.

members have been obtained from the dibromides of the higher alkylens (p. 86),
Ber., 17, 1374 ;—

B. P.

M. P. at 15 mm. sp. gr.

Dodecylidene C,jHjj —9° 105° 0.8097

Tetradecylidene, ...... CuH^j +6-5° I34° 0.8064

Hexadecylidene, Cje^ao 20° 160° 0.8039

Octadecylidene, ....*.. CijHg^ 30° 184° 0.8016

(4) HYDROCARBONS Q, H-in-i-

Various bodies of this series have been obtained from the tar oil (from cannel
coal) boiling as high as 300°. In all probability they result from the polymeriza-
tion of the hydrocarbons Cn H20 _ 2, contained in the coal tar, through the agency
of sulphuric acid.

The lowest member of this series would be vinyl acetylene, CjH^ = CHjiCH.C
: CH. It has not been isolated. Its homologue is-

Valylene, CjHg, with the structure CHj.CHiCH.C ■ CH or CHjiC (CH3).
C : CH. This is obtained from valerylene dibromide, CjHjBr, by the action of
alcoholic potassium hydroxide. It boils at 5°°. aud l^as an alliaceous odor. It
forms precipitates with ammoniacal copper and silver solutions, and yields the
hexabromide CsHgEr^, with 6 atoms of bromine.

The terpenes, CuHjj, are hydrogen addition products of benzene compounds,
and are homologues of the hydrocarbons just described.

(S) HYDROCARBONS C„H2„_6

Diacetylene, C^H, = HC : C.C : CH, is formed from diacetylene dicarbonic
acid on heating its copper salt with potassium cyanide. It is a gas that yields a
yellow precipitate with an ammoniacal silver solution. Iodine converts the silver
compound into di-iodo- diacetylene, Cjlj, a colorless, crystalline body, melting at
101°. It has an odor ^ke that of iodoform. It explodes when heated.

Dipropargyl, CjHg ^ OH : C.CHj.CHj.C : CH. This is isomeric with ben-
zene, but its properties are entirely different. On warming solid crystalline diallyl-
tetrabromide, CgHj^Br^ (see above), with KOH, there is formed dibrom-diallyl,
CjHjBrj (together with a little dipropargyl), a liquid boiling at 205-210°. On
treating the latter compound with alcoholic potash we obtain dipropargyl, CgHj.
This is a very mobile liquid, of penetrating odor, and boiling at 85° ; its specific
gravity at 18' equals 0.81.

The compound C^H^CUj-l- aHjO, which it forms with ammoniacal copper
solutions is siskin yellow in color; that with silver, C.H^Agj -|- aH^O, is white,
but blackens on exposure to the air. Acids again liberate dipropargyl from
these.

If dipropargyl be allowed to stand, or if heat be applied to it, it polymerizes
and becomes thick and resinous. It unites energetically with bromine to C^Hj
Brj and CgHjEr, ; the latter melts at 140°.

Dimethyl Di-acetylene, CH3.C=C.C=C.CH3, is the second isomeride of
benzene. It has been obtained from the copper derivative of allylene, CHj.
C— C.Me. It melts at 64° and boils at 130° [Ber., 20, 564).

HALOGEN DERIVATIVES OF THE HYDROCARBONS.

The halogen substitution products result from the replacement of
hydrogen in the hydrocarbons by the halogens. In general charac-
ter they resemble the compounds from which they have their origin.

ACETYLENE SERIES. 9 1

The following are the most important methods for their prepara-
tion : —

(t) By direct action of the halogens upon the hydrocarbons,
when one or all the hydrogen atoms will suffer replacement, the
hydrides of the halogens forming at the same time : —

' C„Hn. + xCl2 = CnHm-xClx+xHCl.

The action of chlorine is accelerated, and very often also dependent upon direct
sunlight, or the presence of small quantities of iodine. It is the ICIj, which arises in
the latter case, that facilitates the reaction. SbClj also plays the r61e of a chlorine
carrier, since upon heating it yields SbCl, and 2CI. Ferric chloride serves as an
excellent chlorine and bromine carrier (Ahn., 225, 196 and 231, 132). When the
chlorination is very energetic a rupture of the carbon linking takes place (Berichte,
8, 1296, 10, 801). Heat hastens the action of bromine. Usually iodine does not
replace well, inasmuch as the final iodine products sustain reduction through the
hydriodic acid formed simultaneously with them : —

C3H,I+HI = C,H, + I,.

In the presence of substances (like HIO3 and HgO) capable of uniting or de-
composing HI, iodine frequently effects substitution : —

SC3H, + 2I, + IO3H = sCjHjI -1- 3H,0,
2C,H3-+-2l,-f HgO =2C,H,I + H,0 + HgI,.

And in the presence of ferric chloride iodation occurs with the liberation of
hydrogen chloride [Ann., 231, 19S).

In direct substitution a mixture of mono- and poly-substitution products gen-
erally results, and these are separated by fractional distillation or crystallization.

(2) By adding halogens to the unsaturated hydrocarbons : —

CH. CH.Cl

\\ +ci.= l

CHj CH^Cl.

At ordinary temperatures, chlorine and bromine react very vio-
lently ; in the absence of light the action is more regular, and when
it is present, substitution products also arise. Iodine (in alcoholic
solution) generally enters combination only upon application of
heat.

(3) By adding halogen hydrides to the unsaturated hydrocarbons.
In concentrated aqueous solution, HI reacts very readily : —

CH,.CH:CH2 + HI = CHj.CHI.CH,.

Heres^ain we observe the common rule that the halogen atom almost invariably
attaches itself to the least hydrogenized carbon atom (Annalen, 179, 296 and 325 ).
Sulphuric acid attaches itself similarly (p. 81). The reaction proceeds in accord-
ance with the principle of the greatest heat evolution (Ber., 21, Ref. 179).

(4) By replacing the hydroxyl groups of the alcohols C„ H^^ + 1 OH
by halogens. This is the most convenient method of preparing the

92 ORGANIC CHEMISTRY.

mono-halogen products, as the alcohols are very readily obtained.
The transposition is brought about by heating the alcohol prC'
viously saturated with the halogen hydride : —

CjHs.OH + H Br = CjHjBr + H,0.

This rearrangement between the two reacting compounds is, how-
ever, not complete. It depends very much on the 'mass of the
substances reacting, and upon the temperature (compare esters of
mineral and fatty acids). The alteration is most speedy with HI >
however, transpositions sometimes occur in this case, in the higher
alcohols. See p. 95.

The change is most complete when effected by the halogen pro-
ducts of phosphorus: —

C2H5.OH + PCI5 =CjH5Cl -t-PCl,0 + Ha,
SC.H^.OH + PC1,0 = sCjHsCl + PO(OH)3,
SC.Hj.OH-fPCl, =3C,H5C1 + P03H3.

Even here the reaction is not perfect. Phosphoric and phos-
phorous acids are formed, and these convert a portion of the alcohol
into ethereal salts, which constitute the residue after distilling off
the halogen derivatives.

(5) By the action of PClf and PBrj' upon the aldehydes and
ketones, when an atom of oxygen is replaced by two halogen
atoms : —

CH,CHO + PCls = CHj.CHClj + PClsO,

Aldehyde.
Ketone.

The halogen derivatives prepared according to these methods
are partly identical, as will be seen further on, and partly isomeric.
They are generally colorless, ethereal smelling liquids, insoluble
in water. The iodides redden in sunlight, iodine separating. The
chlorides and bromides burn with a green-edged flame.

Nascent hydrogen (zinc and hydrochloric acid or glacial acetic
acid, sodium amalgam and water) can reconvert all the halogen
derivatives, by successive removal of the halogen atoms, into the
corresponding hydrocarbons: —

CHCl, -f 3H, = CH^ + 3HCI.

When the mono-halogen compounds are heated with moist silver
oxide, the corresponding alcohols are produced : —

C,H,I -f AgOH isCjJIs-OH -j- Agl.

HALOGEN COMPOUNDS. 93

Alcoholic sodium and potassium hydroxides occasion the splitting
off of a halogen hydride, and the production of unsaturated com-
pounds: (pp. 80, 87): —

CHj.CHj.CHjBr + KOH = CHj.CHiCH^ + KBr + HjO.

Propyl Bromide. Propylene.

In this reaction the halogen attracts to itself the hydrogen of the least hydro-
genized adjacent carbon atom (compare p. 91). Such a splitting sometimes occurs
on application of heat, .and it appears that the primary alkylogens are more easily
decomposed than the secondary and tertiary (see p. 94).

(I) HALOGEN COMPOUNDS— Ca Ha. + iX.
ALKYLOGENS.

Because of their formation from the alcohols by the action of the
halogen hydrides, the alkylogens are called haloid esters. They are
perfectly analogous to the true esters produced by the action of
alcohols and oxygen acids.

Monochlonnethane, CH3CI, Methyl chloride, is obtained
from methane or methyl alcohol. At ordinary temperatures it is a
gas, that may be condensed to a liquid (by a freezing mixture of
ice and calcium chloride). It boils at — 22°. Alcohol will dissolve
35 volumes of it, and water 4 volumes.

. It is prepared by heating a mixture of i part methyl alcohol (wood spirit), 2
parts sodium chloride, and 3 parts sulphuric acid. A better plan is to conduct
HCl into boiling methyl alcohol in the presence of zinc chloride (J^ part). The
disengaged gas is washed with KOH, and dried by means of sulphuric acid.
Commercial methyl chloride usually occurs in a compressed condition. It finds
application in the manufacture of the aniline dyes, and in producing cold. It is
obtained by heating trimethylamine hydrochloride, N(CH3)3.HC1.

Monochlorethane, C2H5CI, Ethyl chloride, is an ethereal
liquid, boiling at 12.5°; specific gravity at 0° = 0.921. It is
miscible with alcohol, but is sparingly soluble in water.

Preparation. — Heat a mixture of i part ethyl alcohol, 2 parts HjSO^, and_2
parts NaCl. The gas is washed by passing through warm water and condensed in
a strongly cooled receiver. Or HCl may be passed into 95 per cent, alcohol con-
taining % part ZnCIj. Heat should be applied.

If heated with water to 100° (in a sealed tube), it changes to
ethyl alcohol. The conversion is more rapid with potassium
hydroxide. In dispersed sunlight, chlorine acts upon it to form
ethylidene chloride, CH3.CHCI2, and substitution products. Of
these C2HCI5 was formerly employed as ^ther anastheticus.

Monochlorpropane, CsHjCl. Two isomerides are possible : —

Normal propyl chloride, CH3 CHj.CHj.Cl, derived from normal

propyl alcohol, boils at 46.5°. Its specific gravity is 0.8898 at 0°.

94 ORGANIC CHEMISTRY.

Isopropyl chloride, CH3.CHCI.CH3, obtained from the corres-
ponding alcohol, and by the union of propylene with HCl, boils at
37° ; its specific gravity is 0.874 at 10°.

Monochlor-Butanes, C^HjCl, Butyl chlorides. Four isomerides are possi-
ble : two of these arise from the normal and two from the tertiary butane (see p.
43). These (and also their homologues) will be mentioned under the correspond-
ing alcohols.

The alkyl fltiorides are produced when the potassium salts of the alkyl sul-
phates are heated with acid fluoride of potassium. The first four members, from
Methyl Fluoride, CH3FI, to Butyl Fluoride, C4H9FI, are gases with an ethereal
odor.

■ For the preparation of the bromides from the alcohols, the al-
ready made PBrj (or PCIgBrj) (see p. 92) is not essential. Amorphous
phosphorus is taken, alcohol poured over it, and while carefully
cooling, bromine is gradually added. The mixture is subsequently
distilled : —

3C,H,.OH -f- P -I- 3Br = sC^H.Br -f PO3H,.

The distillate is washed with HjO and dilute KOH, dried over
CaCla, and then fractionated. The bromides boil from 22-24°
higher than their corresponding chlorides.

The bromides may be obtained from the chlorides, by heating
with aluminium bromide {Berichte, 14, 1709) : —

SC.H^Cl + AlBr, = sC^H^Br + AlCl,.

Conversely, the bromides are changed to chlorides through the
agency of HgGlj.

Methyl Bromide, CHjBr — Monobrommethane — boils at -\-
4.5° ; its specific gravity is 1.73 at 0°.

Ethyl Bromide, CjHsBr, boils at 39° ; its specific gravity is
1.47 at 13°. Ethylidene I Bromide, CHsCHBrj, and ethylene
bromide, CHjBr.CHsBr, are obtained from it by the action of
bromine.

Propyl Bromide, CsH,Br, from the normal alcohol, boils at
71° ; its specific gravity is 1.3520 at 20°.

Isopropyl Bromide, CsH^Br, from its corresponding alcohol,
boils at 60-63°; >'s specific gravity is 1.3097 at 20°. It is most
conveniently obtained by the action of bromine upon isopropyl
iodide {Berichte, 15,1904).

Upon boiling with aluminium bromide, or by heating to 250°, normal propyl
bromide passes over into the isopropyl bromide (not completely, however,
Berichte, 16, 391). Such a transposition, due to displacement of the atoms in the
molecule, occurs rather frequently, and is termed molecular transposition. In
many instances it may be explained by the formation of intermediate products.
Thus, it may be assumed that the normal propyl bromide, CHj.CHj.CHj.Br, at
first breaks up into propylene, CHj.CHiCHj and HBr (see p. 93), which then,

HALOGEN COMPOUNDS. 95

according to a common rule of addition (p. 92), unite with the propylene to isopro-
pyl bromide, CH5.CHBr.CH3. Similarly, isobutyl bromide, (CH3)2.CH.CH2.Br,
changes at 240° to tertiary butyl bromide, (CH,)jj.CBr.CH 3. The transpositions
occurring on heating the halogen hydrides with the alcohols may be explained in
the same manner.

The iodides are obtained just like the bromides, that is, by heat-
ing a mixture of the alcohols, phosphorus (yellow or amorphous)
and iodine. Concentrated HI converts the alcohols into iodides : —

CjHj.OH + HI = CjHsI + H,0.

Excess of HI, however, again reduces them. (Compare p. 91.)

The polyhydric alcohols (containing several hydroxyl groups) also yield mono-
iodides : —

C,H, (OH), + 3HI = QHJ + I, + 2H,0
C3H5 (OH), + SHI = CjH,! + 21, + 3H,0
C,H3 (OH), + 7HI = C,H,I + 3I, + 4H,0
CeH8(0H), +11HI = C,Hi3l + 5L, + 6H,0.

The mechanism of the reaction will be more carefully studied when we reach
allyl and isopropyl iodides.

Many iodides can be obtained from the chlorides by heating
with Alia (or Cal,) Berichte, 16, 392, and 19, Ref. 166) :

SCjHjCl + AII3 = sCjH,! + AlCV

In some cases HI accomplishes the same result. Conversely the
iodides can be changed to chlorides by heating with mercuric,
cupric or stannic chlorides: —

2C3H,I + HgClj = 2C3H,C1 + Hglj.

Free chlorine and bromine can also replace iodine directly: —

CjHjI + Cl, = C,HjCl + ICl.

As to the action of various metallic haloids upon organic chlor-, brom-, and
iodo- derivatives, see Ann., 225, 146, 171, and 231, 257. These transpositions are,
in general, determined by the thermo-chemical deportment of the compounds.

On exposure to the air the iodides soon become discolored by
deposition of iodine. The iodides of the secondary and tertiary
alcohols are easily converted by heat into alkylens, C„H2„ and HI.
Their boiling points are about 33° higher than those of the corres-
ponding bromides.

Methyl Iodide, CH3I, is a heavy, sweet-smelling liquid, boil-
ing at 45°, and has a sp. gr. = 2.19 at 0°. In the cold it unites
with HjO to form a crystalline hydrate, 2CH3I -|- H^O.

96 ORGANIC CHEMISTRY.

Ethyl Iodide, CjHbIj is a colorless, strongly refracting liquid,
boiling at 72° and having a sp. gr. of 1.975 ^^ °°-

Preparation. — Pour 5 parts alcohol (90 per cent.) over i part amorphous
phosphorus, then gradually add 10 parts iodine and distil. The distillate is
poured back on the residue and redistilled. It is advisable to previously dissolve
the iodine in alcohol or ethyl iodide, and add this to the alcohol containing
phosphorus. In this case yellow phosphorus may be employed.

Propyl Iodide, CaH,!, boils at 102°, and has a specific gravity
of 1.7427 at 20°.

Isopropyl Iodide, CsHjI, is formed from isopropyl alcohol,
propylene glycol, CsHeCOH),, or from propylene, and is most con-
veniently prepared by distilling a mixture of glycerol, amorphous
phosphorus and iodine : —

C3H, (OH), + sHI = CjH,! + 2I, + 3H,0.

Here we have allyl iodide produced first (see p. 98), and this is
further changed to propylene and isopropyl iodide : —

CHj = CH — CHjI + HI = CHj = CH — CH, + Ij,
Allyl Iodide. Propylene,

and

CHj = CH — CHj + HI = CHj — CHI — CH,.

Propylene. Isopropyl Iodide.

Preparation. — 300 gr. iodine and 200 gr. glycerol (diluted with an equal
volume of H^O) are placed in a tubulated retort, and 55 gr. of yellow phosphorus
added gradually. The portion passing over first is returned and redistilled. To
remove admixed allyl ipdide from the isopropyl iodide, conduct it into HI and let
stand. (Annalen, 138, 364.)

Isopropyl iodide boils at 89.9°, and has a specific gravity of
1.7033 at 20°-

The higher alkyl iodides are mentioned under the corresponding
alcohols.

HALOGEN DERIVATIVES— CnHan-iX and C^'R^-^Tii.

As a general thing, the halogen substitution products of the un-
saturated hydrocarbons cannot be prepared by direct action of the
halogens, since addition products are apt to result (p. 91). They
are produced, however, by the moderated action of alcoholic potash,
or AgjO, upon the substituted hydrocarbons C^Hb^Xj. This re-
action occurs very readily if we employ the addition products of
the olefines : —

CjH^Clj -\- KOH = C^HsCl -f KCl + HjO.

Ethylene Monochlor-

Chloride. ethylene.

HALOGEN DERIVATIVES. 97

When the alcoholic potash acts very energetically the hydro-
carbons of the acetylene series are formed (p. 86). Being un-
saturated compounds they unite directly with the halogens, and also
the hydrides of the latter : —

CHj

CHjBr

II + Br, =

1

CHBr

CHBr,

Monochlorethylene, C2H3C1 = CH2:CHC1, or Vinyl chloride (the group
CHjiCH is called Vinyl), derived from ethylene chloride, CH^Cl.CHjCl, and
(although with greater difificulty) irom ethylidene chloride, CHj.CHClj, is a gas
with garlic-like smell, liquefying at — 18° and polymerizing in the sunlight.

Monobromethylene, C^HjBr, Vinyl bromide, is obtained by boiling ethy-
lene bromide with aqueous potassium hydroxide. It possesses an odor similar to
that of the chloride, boils at i6°, and has a specific gravity of 1.52. Under cer-
tain conditions, in sunlight, for example, it is converted into a solid polymeric
modification. It dissolves readily in concentrated sulphuric acid, and if the
solution be boiled with water crotonaldehyde results (^om acetaldehyde that is
formed previously). Vinyl bromide does not react with CNAg or CNK, and,
indeed, does not appear capable of double decompositions. (Berichte, 14, 1532.)

Ethylene Mono-iodide, C2H,I, Vinyl iodide, is obtained fi-om ethylene and
ethylidene iodides, by the aid of alcoholic potash, and boils at 55°; its specific
gravity is 1.98.

Ethylene Dichlorides and Dibronudes: —

Ethylene a-dichloride.

Ethylene o-Dichloride (unsymmetrical) ,is formed fi-om ethylene chloride^
CHjCl. CHClj, by the action of alcoholic potash, and boils at 37°. Ethylene
/3-dichloride (symmetrical) is formed by the union of acetylene, C2HJ, with
SbClj. It boils at 55°. Ethylene a-Dibromide, from bromethylene bromide,
CHjBr.CHBrj, boils at 91°. Ethylene /3-dibromide, formed from acetylene
by addition of Br^, and from acetylene tetrabromide, CjHjBrj, through the
agency of zinc, boils at 110°. Ethylene a-dibromide, with benzene and AlClj,
yields ethylene diphenyl, CHjiCjC^Hj),; but from ethylene ;3-dibromide
dibenzyl is obtained CjH^.CHj.CHj C5H5. {Berichte, 16, 622.)

The unsymmetrical products are inclined to polymerize. This is not the case
with the symmetrical {Berichte, 12, 2076). The ethylene mono-haloids polymerize
similarly, but ethylene itself does not change. It appears, too, that the power of
direct union with oxygen, thereby yielding the chloranhydrides of substituted
acetic acids, is only possessed by the unsymmetrical substitution products, CHj:
CBr, -f O = CHj. Br. COBr. {Berichte, 16, 2918.) For the course of the re-
action see Ber., 21, 3356.

Two isomeric Di-iodo-ethylenes, CHjI. CHjI, are said to form when acetylene
unites with iodine in an alcoholic solution {Ann., 178, 118).

9^ ORGANIC CHEMISTRY.

Three different mono-halogen products are derived from propylene, CHj —
CH = CHg : —

(i) CH3 — CH = CHX (2) CHj — CX = CHj (3) CH,X — CH = CH,.

o-Derivadves. jS-Berivatives. y-Derivatives.

(i) The a-derivatives are obtained from the propylidene compounds, CH, ■
CHj.CHXj (from propyl aldehyde), when the latter are heated with alcoholic
potassium hydroxide, while from the addition products of propylene, CHj.CHBr.
CHj.Br, we obtain the /3-derivatives at the same time. Propylene a-chloride
boils at 35° (see Ber., 20, 1040 for a geometrical, isomeric a-chlorpropylene).
a-Brompropylene boils at 59-60°; its specific gravity at 19° is 1.428.

(2) The ;3-derivatives, CHj.CXiCH,, are prepared in pure condition from the
halogen compounds derived from acetone. Propylene ;3-chloride boils at 23°;
its sp. gr. at 9° is 0.918. Propylene /3-bromide boils at 48°; its sp. gr. at 19° is
1.364.

Continued heating with alcoholic potash causes both a- and /3-varieties to
pass into allylene. Propylene /3-bromide combines in the cold with HBr to form
acetal bromide, CHj.CBrj.CHj, while the alpha variety only unites with it at
loo°, and then yields a mixture of propylene and propylidene bromide (p. loi).
Sulphuric acid and water, aided by heat, convert the /3-chloride into acetone,
CH3.CO.CH3. The a-products especially appear to react with far more difficulty
(like ethylene monochloride) than the /3-varieties (compare the chlorides of
styrolene).

(3) The j'-derivatives of propylene, CHjX — CH =: CHj, are
designated Allyl haloids, because they correspond to allyl alcohol,
CHjrCH.CHjOH. The allyl group (CHjiCH.CHO occurs in
some vegetable substances (mustard oil, oil of garlic). Heated
with alcoholic potash the allyl haloids yield allyl ethyl ether, C3H5.
O.QHj. The ease with which they undergo transpositions is
characteristic, and serves to distinguish them from the a- and
/9-products.

Allyl chloride, C3H5CI, is formed by the action of PCI 3 or HCl upon allyl
alcohol, or by the transposition taking place between allyl iodide and HgClj
(P' 95)- It 's a liquid with an odor resembling that of leeks ; boils at 46°, and
has a specific gravity of 0.9379 *' 20°. If heated to 100° with concentrated
hydrochloric acid it yields propylene chloride, CH-.CHCl.CHjCl (trimethylene
chloride, CH^Cl.CHj.'CH^Cl, is not produced).

Allyl Bromide, C3H5Br, boils at 70-71°; its specific gravity at 0° equals
1. 46 1. Upon warming to 100° C, it combines with concentrated HBr to form
trimethylene bromide, CH^Br.CHj.CHjBr (see p. 102).

Allyl Iodide, C3H5I, is obtained from allyl alcohol, or better,
from glycerol, by the action of HI, or iodine and phosphorus (com-
pare p. 95) :- -

CHjOH CHj

[.OH -f 3HI = CH -f 3H,0 -f- 1^.
CHJ

CH.C

DIHALOGEN COMPOUNDS. 99

We may suppose that at first CHjI.CHI.CHJ forms, but is sub-
sequently decomposed into CHjrCH.CHjI and I^. With excess
of HI or phosphorus iodide, allyl iodide is further converted into
propylene and isopropyl iodide (p. 96).

Preparation. — 150 parts of concentrated glycerol and 100 parts pulverized
iodine are introduced into a tubulated retort, and 60 parts of yellow phosphorus
gradually added to the mixture. When the first action has passed away, the allyl
iodide is distilled ofif, and the distillate washed with dilute potassium hydroxide.
When larger quantities are employed explosions sometimes occur; these may be
obviated if the operation be carried out in a stream of COj gas. (Compare
Annalen, 185, 191 and 226, 206.)

Allyl iodide is a colorless liquid, with a leek-like odor, boiling
at 101°. Its specific gravity equals 1.789 at 16°. By continued
shaking of allyl iodide (in alcoholic solution) with mercury, CsHjHgl
separates in colorless leaflets (see mercury ethyl). Iodine liberates
pure allyl iodide from this : —

C,H.HgI + I, = C^H^I + Hgl,.

DIHALOGEN COMPOUNDS C,Hj„X2.

These derivatives of the paraffins arise by direct substitution,
by the addition of halogens to the alkylens, Cn H^n, and the halogen
hydrides to the substituted alkylens, Cn H^n — i X; and by the action
of the phosphorus haloids upon the aldehydes and ketones (p. 92).
The products thus obtained are of like composition, and are partly
identical, partly isomeric. The direct addition products, Cn H2nX2,
have the halogen atoms attached to two adjacent carbon atoms (see
p. 86). In the compounds resulting from the replacement of the
oxygen of aldehydes and ketones, both halogen atoms are in union
with the same carbon atom : —

CH, CH, CH, CH,

I yields I >CO yields >CClj.

CHO CHCl, CH3/ OR/

Aldehyde. Acetone.

Heated with alcoholic potash, the addition products pass into the compounds
Cn Hzn — I X and Cn H^n — z (page 96). The alkylens result when the dihalogen
compounds are heated with sodium: —

CHj-a CHjs

I + Na, = II + 2NaCl.

CHjCl CH^

Those derivatives, in which the halogens are attached to different carbon atoms,
are capable of forming glycols : —

CHjCl CHjOH

I yields |

CH,C1 CH,OH.

lOO ORGANIC CHEMISTRY.

Methylene Chloride, Dichlormethane, CHjClj, is produced in the cMoiina-
tion of CHjCl, by the action of CI upon CH^Ij or CH,!, and by the reduction of
chloroform by means of zinc and ammonia. It is a colorless liquid, boiling at
41°, and having a specific gravity of 1.36 at 0°.

Methylene Bromide, CH^Brj, results on heatmg CHjBr with bromine
(together with CHBrj), and by the action of bromine upon methylene iodide. It
boils at 81° (98.5°) and has a specific gravity of 2493 at 0°.

Methylene Iodide, CHjIj, is produced in the action of sodium alcoholate upon
iodoform, CHIj, and is best prepared by heating CHCl, or CHI, with fumiiig
HI to 130° :—

CHCI3 + 4HI = CHjIj + I2+ sttCl.

It is a colorless liquid with a specific gravity of 3.34. It boils, with decomposi-
tion, about 182°. At low temperatures it forms shining leaflets, melting at + 4°.

The empirical formula C2H4X2 has two possible structures : —

CH,X CH,

I and I

CHjX CHXj

Ethylene Ethylidene

Compounds. Compounds.

The first originate from ethylene, the second from aldehyde
CH3.COH. The former yield acetylene with alcoholic potash, the

latter acetal, CHj. CH^ ; the former yield glycol, the

latter do not. ^O.CzHs

Ethylene Chloride, QH^Cla, is obtained by the direct union
of equal volumes of ethylene and chlorine gas, or by conducting
ethylene through warm SbCls. It is a colorless, pleasant-smelling
liquid, of specific gravity 1.2521 at 20°, and boils at 84°.

Ethylidene Chloride, CH3.CHCI2, is produced by the chlori-
nation of ethyl chloride (both gases are conducted over animal
charcoal heated to about 300°) and from aldehyde (better paralde-
hyde) by the action of PCls, or phosgene {Ber., 18, 578). On a
large scale it appears as a by-product in the preparation of chloral.
It is a liquid, smelling like chloroform, with a specific gravity of
1 . 1 743 at 20°, boils at 5 7. 7°, and is employed as an anaesthetic. By
further chlorination it yields CHs.CCla together with a little
CHjCl.CHClj. When AICI3 is present, the latter is the only
product.

Ethylene Bromide, CjH^Brj, is formed by saturating bromine
with ethylene gas {Annalen, 192, 244), and is an oily, pleasant-
smelling liquid, boiling at 131" ; its specific gravity is 2.178 at 20°.
At 0° it solidifies to a crystalline mass, fusing at -|- 9°.

Ethylidene Bromide, CzH^Brj = CHs.CHBrj, formed together
with ethylene bromide by the bromination of CjHs.Br (in presence

DIHALOGEN COMPOUNDS. lOI

of AlBra, only ethylene bromide istoroduced), is obtained by the ac-
tion of PClsBrj upon aldehydl. If boils at 110.5°, ^nd has a spe-
cific gravity of 2.082 at 21°.

The formation of ethylene and ethylidene bromides from monobromethylene is
quite interesting. When the latter is heated with very concentrated HBr, ethy-
lene bromide forms, while with more dilute acid ethylidene bromide results.

Ethylene Iodide, C^H^I^, is produced in the union of iodine with ethylene,
by conducting the latter into a solution of iodine in alcohol. It crystallizes from
alcohol in brilliant needles, which rapidly become yellow on exposure to light.
The compound melts at 81°, and at higher temperatures decomposes into CjH^
and 1 2. It may be distilled in an atmosphere of ethylene gas without decom-
position.

Ethylidene Iodide, CH3.CHI2, is obtained from ethylidene chloride by the
action of aluminium iodide (p. 95). It boils at 178°, sustaining partial decompo-
sition ; its specific gravity is 2.84 at 0°. It is also formed by the addition of 2HI
to acetylene.

Four different di-halogen products are derived from propane
CaHg : —

(I) CH-.CHj.CHX,. (2) CHa.CXj.CHj. (3) CHs.CHX.CHjX, and
(4) CH.X.CHj.CH.X.

(1) Derivatives of the first structure, called propylidene compounds, arise from
propyl aldehyde, CHj.CHj.CHO, by the action of PCI5.

Propylidene Chloride, C3H5CI2, is a liquid, with an odor resembling that of
leeks, and boiling at 84-87°. Its spedfic gravity at 10° is 1.443- The bromide,
C,H5Br2, from propylene o-bromide, boils at 130°.

(2) Derivatives of the formula CHj.CXj.CHg are obtained from acetone by
the action of PCI5 and PBrj:—

CH,. CH,.

^CO yields ^CXj,

CH3/ CH,/

Dimethyl Methylene Chloride, CjHeClj = CH,.Ca^.Cn„ methyl chlor-
Bcetol or acetone chloride, is formed by the addition of 2HCI to jiUylene (together
with propylene chloride) : —

CH3 CH3 CH,

C -f2Ha yields CCla and CHCl;

CH CH3 (^H.Cl

and by the chlorination of isopropyl chloride, CH3.CHCI.CH3.

It is a colorless liquid, boiling at 69-70°, and having a specific gravity 1.827 at
16°. /3-Monochlorpropylene is obtained from it by the action of aleohohc potasn
(p. oSV Heated to 150° with water, it changes in part to acetone.

Dimethyl Methylene Bromide, CjHgBr^, from acetone, and from allylene,
by the addition of 2 HBr, boils at 113-116°; its specific gravity at 0° is 1.875-

I02 ORGANIC CHEMISTRY.

(3) We get the derivatives of the structure CHs.CHX.CHjX
by uniting propylene with the halogens : —

CH, — CH = CHj affords CH5.CHX.CHjX.

This class passes into propylene glycol when acted upon by moist
silver oxide; with alcoholic potash they yield CHa.CXiCHj, and
allylene.

Propylene Chloride, CH^Cl, = CHs.CHCl.CHjCl, is pro-
duced, together with acetone chloride, when chlorine acts in sun-
light upon isopropyl-chloride (in presence of iodine the chlorina-
tion extends only to propylene chloride). It boils at 97°, and has
a specific gravity of 1.165 at 14°.

Propylene Bromide, CaHeBr^ = CHs.CHBr.CHjBr, is a
liquid boiling at 141°. It is formed in the bromination of propyl
bromide and isopropyl bromide. Its specific gravity at 17° equals
1.946. Propionic aldehyde and acetone result when propylene
bromide or the chloride is heated, together with H2O, to 200°.

Propylene Iodide, CsHel^ = CHa.CHI.CHJ, results by
the union of iodine with propylene at 50°. It is a colorless oil,
that cannot be distilled without suffering decomposition.

(4) The products of the formula CH^X.CHj.CHjCl are designated trime-
thylene derivatives.

Trimethylene Chloride, C3H6Cl2 = CH2Cl.CHj.CH2Cl, is obtained by
heating the corresponding bromide with mercuric chloride to 160°, It is an
agreeably smelling liquid, that boils at 1 19°, and at 15° has a sp. gr. = 1.201.

Trimethylene Bromide, CjHjClj, results on heating allyl bromide, CH^ ;
CH.CHjBr, vpith concentrated hydrobromic acid. Propylene bromide is pro-
duced at the same time. This can be removed by fractional distillation. (With
HCl the only product of allyl chloride is propylene chloride, CH,.CHCl.CHj
CI.) It is obtained in a purer form on saturating allyl bromide with HBr in the
cold, and letting the whole stand some time {Annalen, igy^ 184). Trimethylene
bromide is a colorless liquid, boiling at 164°, and has a specific gravity of 2.01
at 0°. When treated with alcoholic potash, it yields allyl bromide and allyl ethyl
ether. Trimethylene is the product with sodium (p. 83). Continued boiling
with water converts it into trimethylene glycol.

Trimethylene Iodide, CaHgl^, obtained on heating trimethylene bromide
with sodium iodide, is a colorless oil, boiling near 224°.

.THE HALOGEN COMPOUNDS CnHj^.jXj.

Chloroform, CHCls, Trichlormethane, is formed : by the
chlorination of CH^ or CH3CI; by the action of chloride of lime«
upon different carbon compounds, e.g., methyl or ethyl alcohol, T
acetone, acetic acid ; and by heating chloral with aqueous
potassium or sodium hydroxide : —

CClj.CHO + KOH = CCI3H + CHKOj.

■* Chloral. . Potassium

Formate.

THE HALOGEN COMPOUNDS. I03

In preparing chloroform a mixture of alcohol, bleaching lime, and water is dis-
tilled from a capacious retort {Annalen, 165, 349). It would be an advantage lo
substitute acetone for the alcohol. The chloroform produced is carried over with
the steam and collects in the bottom of the receiver as a heavy oil. It is purified
by shaking with HjSO^ and repeated distillation. At present it is generally
obtained from chloral. Pure chloroform should not color on the addition of con-
centrated sulphuric acid.

Chloroform is a colorless liquid of an agreeable ethereal odor and
sweetish taste. It solidifies in the cold and melts at — 71°. It boils
at 61°, and its specific gravity at 0° equals 1.526. Inhalation of its
vapors causes unconsciousness, and at the same time has an anaes-
thetic effect. It is uninflammable. Chlorine changes it to CCI4.
Potassium formate is produced when chloroform is heated with
alcoholic potash : —

CHCI3 + 4KOH = CHO.OK + 3KCI -f- 2H2O.

The so-called triba'sic formic acid ester, CH (0. C2H5)3, is produced
by treating chloroform with sodium alcoholate. When heated to
180° with aqueous or alcoholic ammonia, it forms ammonium cyan-
ate and chloride. When KOH is present, an energetic reaction
takes place at ordinary temperatures. The equation is —

CHCI3 4- NH3 + 4KOH = CNK -f 3KCI + 4H2O.

Brornoform, CHBrj, is produced in the same way as chloro-
form, by the action of bromine and KOH upon methyl and ethyl
alcohol. It is a colorless, agreeable-smelling liquid, solidifying at
— 9°. It boils at 151° and has a specific gravity 2.83 at 0°.

Iodoform, CHI3. This compound results when iodine and
potash act upon ethyl alcohol, or acetone, aldehyde and other sub-
stances containing the methyl group. Pure methyl alcohol, how-
ever, does not yield iodoform. {Berichte, 13, 1002).

Preparation. — Dissolve 2 parts crystallized soda in 10 parts of water, add I
part alcohol, bring the whole to 60-80°, and gradually introduce I part of iodine.
The iodoform that separates is filtered off. By renewed warming of the filtrate
with KOH and alcohol, followed by the introduction of chlorine, an additional
quantity of iodoform may be obtained.

Iodoform crystallizes in brilliant, yellow leaflets, soluble in
alcohol and ether. Its odor is saffron-like. It evaporates at medium
temperatures; fuses at 119° and distils over with the aqueous
vapor. Digested with alcoholic KOH, or HI, it passes into
methylene iodide, CHjIj.
Two isomeric tri-halogen derivatives may be obtained from^ ethane CjHj : —
CH, — CX3 and CHjjX — CHX^.

a-Trichlor- Ethane, CHa.CCl,, is produced (together with CH^CLCHClj)
by the chlorination of ethyl and ethylidene chloride in sunlight. It is a liquid

I04 ORGANIC CHEMISTRY.

with chloroform-like odor, and boils at 74.1°. Its specific gravity at 0° is 1.346.
If heated with KOH it yields potassium acetate : —

CH3.CCI, + 4KOH = CHj.CO.OK + 3KCI + 2nf>.

Treated with sodium alcoholate it yields the tri-ethyl ester CHg.C(0.QH5),.
Further chlorination of trichlor-ethane produces CHjCl.CClj, boiling at 131°,
CHCI2.CCI3, at 162°, and perchlor-ethane, CC1,.CC1, (see p. 105). CHClj.CHCl^
from dichlor-aldebyde, boils at 113.7° {Berichte, 15, 2563).

;3-Trichlor-Ethane, CH,Cl.CHClj, monochlor- ethylene chloride, is pro-
duced by the union of vinyl chloride, CHj.CHCl, with Clj, and boils at 113.7°.
Its specific gravity at 0° equals 1.422.

a-Tribrom-Ethane, CH^CBr,, has not been formed.

;3-TribiDm. Ethane, CHjCHBr^, monobrom-ethylene bromide, forms upon
brominating ethyl and ethylene bromides, also by addition of bromine to brom-
ethylene, CHj.CHBr. It boils at 187°; its specific gravity at 21° equals 2.610.

Trisubstituted propane, C3H5XJ, can have five structural forms.

The most important derivatives are those having the formula
CHjX.CHX.CHjX. They correspond to glycerol, CH^COH).
CH(OH).CHj(OH). The trivalent group CHj.CH.CH^, present
in them, is termed glyceryl. They are produced by the addition of
chlorine or bromine to allyl chloride and bromide : —

CHj:CH.CHj.Cl + Clj = CHjCl.CHCl.CHjCl;

or by the action of PCls upon dichlbrhydrin, which is derived
from glycerol :—

CH,a CH„C1

I J.

CH.OH + PCK = CHCl + POCI3 + HCl.

CHjCl CHjCl

Moist silver oxide converts them into glycerol.

Glyceryl Chloride, C3H5CI3, allyl trichloride, triehlorhydrin, is a liquid vvith
an odor resembling that of chlorofonn, and boiling at 158°. Its specific gravity
at 15° equals 1.4 17.

Glyceryl Bromide, CjHjBrj, tribromhydrin, is best obtained by the action
of bromine upon allyl iodide : —

C3HJ+4Br = C,H,Br3 + IBr.

It crystallizes in colorless, shining leaflets, fusing at 16°, and boiling at 220°.
Glyceryl Iodide, C3H5I3, appears not to exist. It decomposes at once into
allyl iodide and I, (p. 98).

Among the higher substitution products may be mentioned the
following carbon haloids : —

Tetrachlor-methane or Carbon Tetrachloride, CClj, is
formed by the action of chlorine upon chloroform, and by conduct-
ing % mixture of CI and CSj through tubes heated to redness.

NITRO-DERIVATIVES OF HYDROCARBONS. I05

Preparation. Chlorine is conducted through boiling chloroform exposed to
sunlight, or through a mixture of CSj and SbClj. In the latter case, sulphur
chloride is formed at the same time. This may be decomposed by shaking with
KOH.

It is a pleasant-smelling liquid, boiling at 76-77°. Its specific
gravity is 1.631 at 0°. At — 30° it solidifies to a crystalline mass.
Heated with alcoholic KOH, it decomposes according to the fol-
lowing equation : —

cell 4- 4KOH = COj 4- 2H,0 + 4KCI.

When the vapors are conducted through a red-hot tube, decom-
position occurs ; CjCl, and CjCls are produced.

Tetrabrommethane, CBr^, obtained by the action of brom-iodide upon
bromoform or CSj, crystallizes in shining plates, melting at 92.5°, and boiling,
with but little decomposition, at 189°.

Tetraiodomethane, CI^, carbon iodide, is formed when CCl^ is heated with
aluminium iodide (p. 95). It crystallizes from ether in dark red, regular octa-
liedra, of specific gravity 4.32 at 20°. On exposure to air it decomposes into
CO, and I. Heat accelerates the decomposition.

Perchlorethane, CjCl,, is the final product in the action of CI upon CjHjCl
or CjHjClj. It is a crystalline mass, with a camphor-like odor and specific gravity
2.01. It melts (in a capillary tube) at 187-188°. At ordinary pressure it vapor-
izes without fusing, as its critical pressure (compare Inorganic Chemistry), lies
above 760 mm. It boils at i85°.5 under a pressure of 776.7 mm. It is readily
soluble in alcohol and ether. When its vapors are conducted through tubes heated
to redness, it breaks up into Clj and ethylene perchloride, C^Cl^. This is a
mobile liquid, boiling at 121°. Its specific gravity at 20° is 1.6226.

Perbromethane, CjEr^, is a colorless crystalline compound, sparingly soluble
in alcohol and ether. At 200° it decomposes into Br, and ethylene perbromide,
CjBr^, which consists of colorless crystals, melting-at 53°.

Perchlormesole, C^Clg, is formed on heating hexyl iodide or amyl chloride
with IClj. It melts at 39°, and boils at 284° (Berichte, 10, 804).

NITRO-DERIVATIVES OF THE HYDROCARBONS.

By this designation is understood compounds of carbon in which
the hydrogen combined with the latter is replaced by the mono-
valent nitro-group, NOj. The carbon is directly united to the
nitrogen by one affinity. A universal method for the production
of nitro-compounds consists in acting upon the hydrocarbon deriv-
atives with concentrated nitric acid : —

C,H, -f NO3H = C,H, (NO,) + H,0.

The reaction is promoted by the presence of HjSOi, which serves to
combine with the water that is generated. The fatty bodies capable
of this reaction are exceptional ; the benzene derivatives, however,
readily yield nitro-derivatives.
9

Io6 ORGANIC CHEMISTRY.

A common method for the preparation of the mono-nitro deriv-
atives of fatty hydrocarbons — the nitro-paraffins — consists in
heating the iodides of the alcohol radicals with silver nitrite
(F. Meyer): —

C.HJ + AgNO, = C3H5.NO2 + Agl.

The isomeric esters of nitrous acid, such as CjHj.O.NO arise (see Btrichte,
I5> 1574) in tliis reaction. From this we would infer that silver nitrite con-
ducted itself as if apparently consisting of AgNOj and Ag.O.NO. (Potassium
nitrite does not act like AgNO^). Since, however, CH3I only yields nitro-
methane, and the higher allcyliodides decompose more readily into alkylens the
greater the quantity of nitrous acid esters, it would appear that the formation of
esters is influenced by the production of alkylens, which afterwards form esters
by the union with HNO^ (compare Annalen, 180, 157, and Ber., 9, 529).

The nitro-compounds generally decompose with an explosion, if
quickly heated. They are not broken up by sodium or potassium
hydroxide. These reagents convert the isomeric nitrous esters,
with ease, into nitrous oxide and alcohol. Nascent hydrogen
reduces the mono-nitro derivatives to araido-corapounds, by con-
verting the group NO2 into NHj — the amido group: —
C.Hj.NO^ + 3H2 = C.H^.NH, + 2H,0.

The compounds resulting from the action of nitrogen tetroxide upon the alky-
lenes, e. g., C^H^NjO^, are not nitro-derivatives ; they belong to the class known
as nUrosates.

The nitroso-compounds, containing the group NO attached
to carbon, are classified with the nitro-compounds. Few of them are
known. The pseudo-nitrols probably belong to this class (p. no).
Most of the compounds resultftig from the action of nitrous acid
are isonitroso- and not nitroso-derivatives {Ber., 20, 331 ; 21, 1294).
The nitroso-amines, (CH3)2N.NO, form another class of nitroso-
compounds. In them the nitroso-group is linked to nitrogen. Their
treatment will be found under the corresponding amines.

The isonitroso-, or oximido-compounds — (CHj^.C : N.OH
— containing the bivalent oximid group = N.OH linked to car-
bon— are isomeric with the above nitroso-derivatives. They are
formed, especially when nitrous acid acts upon bodies containing
the group CHj attached to two CO groups. They also result from
the action of hydroxylamine upon ketones R.CO.R, and aldehydes
R.COH:—

Ch'/'^° + HaN.OH = ^^s^QN.OH -|- H^O.

Consequently these isonitroso-compounds will be treated with
the derivatives from which they originate. The so-called alkyl-
nitrolic-acids may be included with them. (See p. 109.)

NITRO-PARAFFINS. I07

The nitroso derivatives (of the benzene class and the nitroso-amines) give blue
colorations in their action upon a mixture of phenol and sulphuric acid, especially
after dilution with water and super- saturation with alkali. The isonitroso-com-
pounds, however, do not yield this reaction [Berickte, 15, 1529).

NITRO-PAKAFFINS C„ Hj. + 1 (NO^.)

Those formed by the action of silver nitrite upon the alkyl-
iodides are colorless liquids almost insoluble in water. They are
rather stable, distil without decomposition and decompose with
difficulty. It is worthy of note that they possess an acidic charac-
ter (distinctive from the halogen substitution products) : this is in-
dicated by the substitution of metals for one hydrogen atom, through
the action of alkaline hydroxides : —

CH3.CH,(NO,) 4- KOH = CH3.CHK(N02) + H,0.

The nitro-group always exerts such an acidic influence upon hy-
drogen linked to carbon ; the further addition of halogens or nitro-
groups increases the same, but it is confined to the hydrogen linked
to the same carbon atom. Thus the compounds : CHs.CHBr(N02),
brom-nitroethane, CH3.CHCN02)2,di-nitroethane, CH(N02)3, nitro-
form, etc., are strong acids, while CHs.CBr^^NOj) and {CR^y/Z
(N02)2, /J-dinitro-propane, etc., possess neutral reaction and do not
combine with bases.

The nitro-paraffins may be viewed as isonitroso-compounds {Ber., 20, 531, and
Ref. 296).

For compounds resulting from the action of sodium ethylate and the alkyl
iodides upon the nitro ethanes, e.g., CgH^NO, see Ber., ai, Ref. 58 and 710.

Zinc ethide converts the nitro-paraffins into tri-ethyl-hydroxylamines {Ber., 22,
Ref. 250). Brom-nitro ethane, CH3.CHBr(N02), and zinc methyl yield nitror
isopropane.

Nitromethane, CH3.NO2, is produced by boiling chloracetate
of potassium, CH2CI.COOK, with potassium nitrite. In this in-
stance it is very probable nitro-acetic acid is first formed, but it
subsequently breaks up into nitromethane and carbon dioxide : —
CHj.NOj.CO2H = CH3NO2 -f COj.

It is an agreeable-smelling, mobile liquid, sinking in water and
boiling at 101°. Mixed with an alcoholic sodium hydroxide solur
tion it gives a crystalline precipitate, CHjNaCNOj) + C2H6O, which
loses alcohol on standing over sulphuric acid. Salts of the heavy
metals precipitate metallic compounds (like CH2Ag(N02)) from
the aqueous solution. These are in most cases violently explosive.
Nitromethane is liberated again from the salts by mineral acids.

I08 ORGANIC CHEMISTRY.

Heated with concentrated HClto 150° nitromethane breaks up into
formic acid and hydroxylamine : —

CH3.(N0,) + H,0 = CH.O^ + NH,.OH.

Chlorine water converts sodium nitromethane into nitrochlormethane, CHjCI.
(NO2), which is an oil boiling at 122°. In like mapner, through the agency of
bromine, we obtain bromnitromethane, CH2Br{NO)2, a pungent smelling oil,
boiling at 144°, from which are also prepared dibrom-, and tribrom-nitromethane,
CHBr2(N05j) and CBr8(N02).— Bromopicrin (p. 113). The first three bodies
have an acid reaction and dissolve in alkalies.

Nitroethane, C2H5.NOJ, is similar to nitromethane. It boils at
113-114° and its specific gravity at 13° equals 1.058. Nascent
hydrogen converts it into CjHj.NHj. Heated to 140° with con-
centrated hydrochloric acid, it decomposes into acetic acid and
hydroxylamine. Ferric chloride imparts a blood-red color and
copper sulphate a dark green to the sodium compound.

Bromine converts nitroethane, in alkaline solution, into bromnitroethane, CHj.
CHBr(N02), an oil with a pungent odor, boihng at 147°, and into dibromnitro-
ethane, CHg.CBr2N02, boiling at 105°. The &st reacts strongly acid and dis-
solves in NaOH to CH3.CNaBr(N02); the second is neutral and insoluble in
alkalies.

o-Nitropropane, C3H,.N02 = CH,.CH2.CH2.N02, boils at 125-127°.
;8-Nitropropane, (CH3)2CH.N02, boils from 115-117°. Both have an acid
reaction and yield salts with the alkalies.

Brom-a nitropropane, CH3.CH2.CHBr(N02), boiling at i6o-i65°,has a strong
acid reaction and dissolves in alkalies. On the other hand, dibrom -o-nitro-
propane, CH3.CH2.CBr2(N02), boiling at 185°, is a neutral compound insoluble
in alkalies. Brom-;3-nitropropane, (CHj)jCBr(N02), boihng at 148-150° is also
a neutral compound (see p. 107).

Nitrobutanes, C^H5.N02 (compare Butyl alcohols). Normal nitrobutane,
CHj.CHj.CHj.CHj.NOj. boils at 151° and yields normal butylamine by

reduction. Secondary nitrobutane, CH3.CH2.CH(N02).CH3 =;^|^5"^CH.N02,

boils about 140°. Nitroisobutane, (CH3)2CH.CH2.N02, boils at 137-140°, and
has an odor resembling that. of peppermint. The three nitrobutanes are acid, dis-
solve in alkalies and yield bromine derivatives. Tertiary nitrobutane, (CH3) JC.NO2,
on the contrary, boiling at 120° is a neutral compound, insoluble in alkalies.

Nitroisoamyl, CjHji.NOj, obtained from amyl-alcohol of fermentation, boils
at 150-160° and yields metallic compounds.

Nitropropylene, CjHj.NOj, allyl nitryl, from allyl bromide, is an oil boiling
at 96°.

Nitroalkylens, Cn Hjn — i(N02), are formed in the action of nitric acid upon
some alkylens and tertiary alcohols. Thus there is a nitro-butylene, CjHj(N02),
obtained from isobutylene, (CH3)2C:CH2, and trimethyl-carbinol (6113)30.06.
It boils about 156°. A nitroamylene, C,Hg(N02), is also obtained from dimethyl

ethyl carbinol ^ r H^ f '--•OH. Upon reduction, these nitroalkylens do not yield

amido-compounds, but part with the nitrogen as ammonia or hydroxylamine.

NITRO-PARAFFINS. I09

The varying depoitment of the nitro-paraffins with nitrous acid (better NOjK
and HjSO^) is very interesting, according as they are derived from primary,
secondary or tertiary radicals, (p. 46).

On mixing the primary nitro-compounds (those in which NOj is attached to
CHj) with a solution of NOjK in concentrated potassium hydroxide and adding
dilute H2SO4, the solution assumes in the beginning an intense red color and
the Ethyl-nitrolic acids are produced. Their structure very probably corre-
sponds to the formula —

N.OH
CH J .C^ ethyl nitrolic acid.

The nitrolic acids are colorless crystalline bodies, soluble in ether. They behave
like acids. Their alkali salts are dark red in color — hence the appearance, in the
beginning, of a red coloration, which disappears in presence of excess of sul-
phuric acid and reappears on addition of alkali.

The nitro-compounds of the secondary radicals (those in which NO^ is joined
to CH), when exposed to similar treatment, yield a dark blue coloration, after
which colorless compounds — the pseudo-nitrols — separate. These are not turned
red by addition of alkali : —

^HaXcHNO, yields ^^ >C<^^^ •

In the solid state pseudo nitrols are colorless ; when liquid or in solution they
are dark blue.

The nitro-compounds of tertiary radicals (like (CH3)3C.N02) do not react with
nitrous acid and do not yield colors. Therefore, the preceding reactions serve as
a very delicate and characteristic means of distinguishing primary, secondary,' and
tertiary alcoholic radicals (in their iodides) from each other (secondary nitro-pen-
tane no longer exhibits the reaction). In a similar manner the primary and sec-
ondary nitro-derivatives may be detected in a mixtiBe at the same time {Berichte,
9, 539, and Annalen, 180, 139).

NO,
:^ + H,0,

OH

The alkyl-nitrolic acids, produced by the action of nitrous acid
(or NO2K and H2SO4) upon the primary nitro-paraffins (see
above) : —

CH,.CH2(NO)^ + NO.OH = CH,.C/^
* Nj

may be prepared synthetically by treating the dibrom nitro-paraffins

with hydroxylamine : —

^ ./NO,

CH3.CBr,(N0,) -f H,N.OH = Cn,.C^ ^ ^HBr.

^N.OH

Therefore they are to be regarded as isonitroso- or oximid -com-
pounds (see p. 106).

The nitrolic acids are solid, crystalline, colorless, or family-

no ORGANIC CHEMISTRY.

yellow colored bodies, soluble in water, alcohol, ether, and chloro-
form. They are strong acids, and form salts with alkalies that are
not very stable, yielding at the same time a dark red color. They
are broken up into hydroxylamine and the corresponding fat acids,
by tin and hydrochloric acid. When heated with dilute sulphuric
acid they split up into oxides of nitrogen and fatty acids.

/NO,
Methyl Nitrolic Acid, CH^ , forms colorless prisms, fusing at 54°.

N.OH
It decomposes into formic acid and nitrogen oxides.

NO,
Ethyl Nitrolic Acid, CHj.C^ . Bright yellow prisms, of sweet taste,

^N.OH
melting at 81-82°, and decomposing when covered with concentrated HjSO^,
into acetic acid and nitrogen oxides.

NO,
Propyl Nitrolic Acid, CHj.CHj.C^ . Bright yellow prisms, melting

^NO.H
at 60°, with decomposition.

By the action of sodium amalgam upon the alkyl-nitrolic acids, and also upon
dinitro-paraiifins, the lieucauTolic acids, like (C^H^N^O),, are produced. These
probably correspond to the azo-compounds of the benzene group {Anna/en,
214, 328).

The pseudo-nitrols, isomeric with the nitrolic acids, and formed
by the action of nitrous acid upon the secondary nitro-paraffins (see
p. 109) :—

.NO,
{CH3.),CH(N0,) + NO.OH = (CH3),C<^ + H,0,

Isonitro-propane NO

are to be viewed as nitro-nitroso compounds. They are more easily
produced by the action of N2O4 upon ketonoximes (see these) (^Ber. ,

21, 507):—

/NO,
4(CH,),C : N.OH + 3N,0^ = 4{CK^)fi( + 2H,0 + 2NO.

^NO

They are, in all probability, the nitric acid esters of the acetoximes,
(CHj),C = N.O.NO, (^1?^., 21, 1294). The pseudo-nitrols are
crystalline bodies, colorless in the solid condition, but exhibiting
a deep blue color when fused or dissolved (in alcohol, ether, chloro-
form). They show a neutral reaction, and are insoluble in water,
alkalies and acids. Dissolved in glacial acetic acid, they are
oxidized by chromic acid to dinitro-compounds.

NO,
Propyl Pseudonitrol, (CH.),Cr , nitro-nitroso-propane, is a white

^NO
powder, crystallizing from alcohol in colorless, brilliant prisms. It melts at 76°,
to a dark blue liquid, and decomposes into oxides of nitrogen and dinitropro-
pane. Chromic acid changes it to ;3-dinitropropane and acetone.

NITRO-PARAFFINS.

C,H NO,

Butyl Pseudonitrol, .C( , is a colorless, crystalline mass, melt-

ens'^ \NO
ing at 58°. In its fused state, or when dissolved, it exhibits a deep blue color.

The dinitro-derivatives of the paraffins are obtained by the oxida-
tion of the pseudo-nitrols, and by the action of KNO2, upon the
monobrom-derivatives of the nitro-paraffins : —

/NO,
CH3.CHBr(N0,) -f NOjK = CH3.CH/ -f KBr.

^NO,

They also result from the acetones by action of concentrated HNO3. Thus
from diethyl ketone, ^CjHjJjCO, we get dinitroethane, from a-djpropyl ketone,
(C.H.jjCO, a-dinitropropane, etc. Methyl-propyl ketone yields a-dinitro-propane
(.ff^»-., 15, Ref. 56). ^

They are also produced in an analogous manner from the alkylized aceto-acetic
esters (see these) on warming the latter with HNO3 {Berichte, %$, 1495) = —

CH,.CO.C(R)H.COj.C2H5 yields CR^.CO^n -f C(R)H(N02)^ + CO,.

The secondary alcohols (isopropyl alcohol excepted) yield dinitro-parafEns
with nitric acid, sustaining at the same time a decomposition analogous to that of
the corresponding ketones {Ber., 18, Ref. 217).

Dinitroethane, CH3.CH(N02)2, from brom-nitroethane, is a colorless oil, of
specific gravity 1.35 at 23°. It boils at 185-186°. Tin and hydrochloric acid
change it to hydroxylamine, aldehyde and acetic acid. It reacts acid and dis-
solves in potassium hydroxide, forming CHj.CK(N02)2, which crystallizes in
yellow prisms. An oil, CH3.CBr(N02)2, that cannot be distilled, is produced by
the action of bromine.

as-Dinitropropane, CHg.CH2.CH(N0j')2, from brom-nitropropane, is a
colorless oil of specific gravity 1.258 at 22°; it boils at 189°, reacts acid and
dissolves in the alkalies, forming salts.

/3-Dinitropropane, (CH3)jC(N02)2, is also produced by acting upon isobu-
tyric and isovaleric acids {Berichte, 15, 2325) with HNOj. It forms white camphor-
like crystals, fusing at 53° and boilmg at 185.5°. I' '^ neutral and insoluble in
alkalies. Tin and hydrochloric acid change it to acetone and hydroxylamine.
. ^-Dinitrobutane, CH3.CH2.C(N0j)2.CH3, from butyl pseudo-nitrol, boils at
199° and does not dissolve in alkalies. Hydroxylamine and methyl ethyl ketone
are the products it furnishes when acted upon by tin and hydrochloric acid.

DinitTohexane, CjHi2(N02)2, from methyl hexyl carbinol, boils at 2I2°C.

Nitrosales and Nitrosites. These compounds are produced by the action of
nitrogen teU-oxide and nitrogen trioxide upon the alkylenes : * —

^O.NO.

C6Hi„-l-N20. = C5H,^

N.OH
O.NO

C3H,„-fN203=C,H,(^^^

*Wallach, Ann., 241, 288; 245, 241; 248, 161. Ber., 20, Ref. 638; 21,
Ref. 622.

112 ORGANIC CHEMISTRY.

They contain an iso-nitroso-group, which is also present in the allcyl-nilrolic
-acids (p. 109), and the ketonoximes (see these). In addition to this the nitrate
group (O.NOj), and nitrite group (O.NO) are prfesent. In consequence they
manifest at the same time the properties of nitric and nitrous acid esters. The
nitrosates can be formed by the action of nitric acid and amyl nitrite on the
alkylenes {Ber., 21, Ref. 622). If hydrochloric acid be substituted for nitric acid
in diis reaction the NUroso-chlorides will result. These contain chlorine instead

/^'
^N.OH.

The nitroso-nitrates, or nitrosates, are very reactive, and like the nitric acid
esters react so that the nitrate group is replaced. -With the amines, such as ethyl-
amine and aniline, they yield the Nitrolamines : —

of the nitrate group, e.g., amylene-nitroso-chloride, CjHji

C5H / + NH,.C,H5 = C,H / + NO,.OH.

^N.OH ^N.OH

Amylene-nitrol-
aniline.

When these are boiled with water the isonitroso-group splits off (similar to the
ketonoximes, see same), and is replaced by oxygen, thus giving rise to the Keto-
amines : —

C,n,(^ + H,0 = CjH^O.NH.C.Hs + H.N.OH.

^N.OH Amylene-keto-

anilide.

Cyanides (nitriles) result on treating the nitrosates with potassium cyanide : —

-O.NO, ,CN.

^i^t\. + CNK ^ CjHgi' from these the corresponding acids

■^N.OH ^N.OH;

can be obtained.

^-Isoamylene-nitrosate, C5Hg(N.OH).O.N02, formed from ordinary amylene
(p. 84) (see above and Ber., 22, Ref. 16), crystallizes in cubes or needles,
melting at 97°. Its Nitro-anilide, C5Hg(N.0H).NH.CgH5, melts at 141°.
Potassium cyanide converts the nitrosate into Isonitrosoeyanide, C5Hg.(N.0H).
CN, melting at 100°. By saponification of the latter the acid, C5H9(N.OH).
CO^H, is formed. This melts at 97° and suffers further decomposition into COj
acd C5Hj„(N.0H). The latter compound is identical with methyl-isopropyl
ketoxime, (CH3)2.CH.C(N.OH).CH3. The structure of these derivatives, there-
fore, corresponds to the following formulas: —

(CH,)2.C.O.NO, (CH3),.C.CN. (CH3),C.C02H

(CH8).C(N.OH) CHj.qN.OH) CH,,.C(N.0H).

Iso-amylene Iso-amylene- Ketoxime-

Nitrosate. iso-nitroso-cyanide. dimethyl-acetic Acid.

We may note the following among the nitro-compounds, result-
ing from the action of nitric acid: —

Nitroform, CH(N02)3, Trinitromethane, is produced in slight
quantity when nitric acid acts upon various carbon compounds. It
is most conveniently prepared from trinitro-acetonitrile, Cj(NOj)sN.

NITRO-PARAFFINS.

"3

(See this.) When the latter is boiled with water, carbon dioxide is
generated, and the ammonium salt of nitroform produced : —
C(NOj)3.CN + 2H,0 = C(N02)a.NH, + CO,.

Trinitro-acetonitrile Ammonium Nitroform.

The last is a yellow crystalline compound, from which con-
centrated sulphuric acid separates free nitroform. This is a
colorless, thick oil, solidifying below -|- 15° to a solid, consisting
of cubes. It dissolves rather easily in water, imparting to the
latter a yellow color. It explodes when heated rapidly.

Nitroform behaves like a strong acid ; the presence of three
nitro-groups imparts to hydrogen, in union with carbon, an acid
character. Therefore it unites with NH3 and the alkalies to form
salts like C(N02)aK, from which acids again liberate nitroform
(p. 107). The hydrogen of nitroform can also be replaced by
bromine or NO,.

Brom-nitroform, C(N02)3Br, Brom-trinitromethane, is produced by per-
mitting bromine to act for several days upon nitroform exposed to sunlight. The
reaction takes place more rapidly by adding bromine to the aqueous solution of
the taercury salt of nitroform. In the cold it solidifies to a white crystalline mass,
fusing at -)- 12°. It volatilizes in steam without decomposition.

Tetranitromethane, CCNOj)!, results on heating nitroform
with a mixture of fuming nitric acid and sulphuric acid. It is a
colorless oil that solidifies to a crystalline mass, fusing at 13°. It
is insoluble in water, but dissolves readily in alcohol and ether. It
is very stable, and does not explode on application of heat, but
distils at 126° without sustaining any decomposition.

Nitrochloroform, C(N02)Cl3 — Chloropicrin, trichlor-nitro-
methane, is frequently produced in the action of nitric acid upon
chlorinated carbon compounds (chloral), and also when chlorine
or bleaching powder acts upon nitro-derivatives (fulminating
mercury, picric acid and nitro methane).

In the preparation of chloropicrin, 10 parts of freshly prepared bleaching powder
are mixed to a thick paste with cold water and placed in a retort. To this is
added a saturated solution of picric acid, heated 1030°. Usually the reaction
occurs without any additional heat, and the chloropicrin distils over with the
aqueous vapor [Annalen, 139, in).

Chloropicrin is a colorless liquid, boiling at 112°, and having a
specific gravity of 1.692 at 0°. It possesses a very penetrating
odor that attacks the eyes powerfully. It explodes when rapidly
heated. When treated with acetic acid and iron filings it is con-
verted into methylamine : —

CCIjCNO^) + 6H2 = CH3.NH, + 3HCI -f 2H2O.

Bromopicrin, CBr3(N02)— Tribrom-nitromethane, is formed, like the pre-
ceding chloro-compound by heating picric acid with calcium hyjjobromite (calcium

114 ORGANIC CHEMISTRY.

hydroxide and bromine), or by heating nitrfpietba^e with bromine (p. ?o8). It
closely resembles chloropicrin and becomes crystalling below -|- io°. It can be
distilled in a vacuum without decomposition.

ALCOHOLS, ACIDS AND THEIR DERIVATIVES..

All organic compounds are derived from the hydrocarbons,
the simplest derivatives of carbon, by the replacement of the
hydrogen atoms by other atoms or atomic groups. The different
groups of chemical bodies are characterized in their specific
properties by the presence p,f such substituting side-groups. Thus
the alcohols contain OH, the aldehydes C.HQ, the acids COOH,
etc., etc.

In the following pages we will consider the carbon compounds
according to the number of side groups yet capable of replace-
ment— as ijqoaovaleiit, divalent, trivalent, etc., compounds. To
each of these groups other derivatives are attached bearing intimate
genetic connection with them.

By the replacement of one atom of hydrogen of the hydrocarbons
by the hydroxyl group OH we get the monovalent (monohy-
dric) alcohols, e. g. C2H5.OH, in which the H of OH is capable
of further exchange. The thio-alcohols or mercaptans, <?. g. etbj;l
mercaptan, C2H5.SH, are analogous to these. Ethers result from
the union of two monovalent alcohol radicals throwgh the agency
of an oxygen atom ; corresponding to those are the thio^ethers or
sulphur alky Is : —

Ethyl Ether. Ethyl Sulphide.

The Aniines, C^Hs-NHj, Phosph|nes and the SQ-called
metallo-organic compounds are also derivatives of the alcohol
radicals.

When two hydrogen atoms of a methyl group, CH3, of the
hydrocarbons are replaced by one oxygen atom the aldehydes
result. These are easily obtained fi;om the alcohols by o}^i,dation, :—

CHj.CH^.OH + 0 = CHj.CHO -|- H^O.

Ethyl Alcohol. Acetaldehyde.

The group CHO (aldehyde group), is characteristic of aldehydes.
The ketones are compounds in which two hydrogen, atoms of an
intermediate carbon atprij (see p. 40) are replaced by one a,tom pf
oxygen : —

CHj.CaCHj = ^^s^^CO Eimethyl-ketoos.

They are characterized by the group CO, united to. two alkyls>

ALCOHOLS, AeiDS AND THEIR DERIVATIVES. 1 15

When the two hydrogen atoms attached to the carbon carrying
OH are replaced by oxygen, we obtain the monobasic acids : —

CH,

CH»

1 yields

I

CHj.OH

CO. OH

Ethyl Alcohol.

Acetic Acid,

The carboxyl group — CO. OH — is characteristic of organic acids.
The hydrogen atom present in it may be readily replaced by met-
als, giving rise to salts.. Or, the acids may be viewed as com-
pounds of OH with residual atomic groups (i?. g. CH3.CO ^QHjO,
acetyl) designated acid radicals. Th« latter, like the alcoholic
radicals, are capable of entering into further combinations : —

C.H.aCl r^H^n'^O^ C^HjO.NH,

Acetyl Chloiide. Acetvf Oxide '***'''' ■^"'^'^

The following formulas exhibit the connection between alcohols,
aldehydes (or ketones) and acids : —

C^HeO C,H,0 C.H^O,

Alcohol, Aldehyde. Acid.

The unsaturated hydrocarbons also yield unsaturated alcohols,
aldehydes, acids, etc.

The dihydric alcohols, known as glycols, are formed when two
hydrogen atoms of the hydrocarbons are replaced by hydroxyl : —

CH,.OH

Ethylene Glycol.
H«.OH.

I

In these, four hydr(^;en atoms can be replSaeed by oxygen, giving
rise to the dihydric mombmsic and the dihydric dibasic acids : —

CH^OH CO.OH

CO.OH CO.OH

Dihydric Monobasic Acid. Dibasic Acid.

The number of CO.OH groups in the adds determines their
basicity. The number of h^roxyl- groraips present is indicated by
the terms vaoao-mlent, dx-valent, tit. In the same manner, tri-
valent (trihydric), mono-,, di- and tri-basic acids,, etc,, are derived
from the trivalent alcohols.

The, relations ofthe alcohols and acids to each other, with refereace
to their valence and basicity, is manifest from the following table : —

ii6

ORGANIC CHEMISTRY.

ALCOHOLS.

ACIDS.

I -basic.

2-basic.

3-basic

1

CH3.OH

Methyl Alcoliol.

C^Hj.OH
Ethyl Alcohol.

CHO.OH
Formic Acid.

CH,.COOH

Acetic Acid.

1

Q

CHj.OH

CHj.OH
Ethylene Glycol.

CaH.COH),
Propylene Glycol.

CHj.OH

1
CO.OH

GlycoUic Acid.

<-2"4<co.OH

Lactic Acid.

CO.OH

1
CO.OH

Oxalic Acid.

p„ /CO.OH

*-"2<-CO.OH

Malonic Acid.

1

>

CHj.OH

CH.OH

CHj.OH

Glycerine.

CHjj.OH

CH.OH

1
CO.OH

Glyceric Acid.

CO.OH
CH.OH
CO.OH

Oxymalonic Acid'.

C3H5 \ CO,H '
ICO.H

Tricarballylic Acid.

C,H,.(OH),
Erythrite.

C4H^0.(0H)^
Erythric Acid.

C,H,0,.(OH),
Tartaric Acid.

C,H,03.(0H),

Citric Acid.

:C,H,.(OH),
Mannite,

CeHeO.(0H)e
Mannitic Acid.

CeH,0,.(OH),
Mucic Acid.

MONOVALENT COMPOUNDS.

MONOVALENT ALCOHOLS.

MONOHYDRIC ALCOHOLS.

The monovalent alcohols contain one hydroxyl group, OH;
bivalent oxygen links the monovalent alcohol radical to hydrogen :
CH3.O.H, methyl alcohol. This hydrogen atom is characterized
by its ability, in the action of dcids upon alcohol, to exchange
itself for acid residues, forming compound ethers or esters, corres-
ponding to the salts of mineral acids : —

CjHj.OH -f NOj.OH :

Ethyl Alcohol.

= C2H5.O.NO2 + H,0.

Ethyl Nitrate or
Nitric Ethyl Ester.

Alkyls and metals can also replace the hydrogen in alcohol : —

CjH^.O.CHs

Ethyl-methyl Ether.

CjHj.ONa.
Sodium Ethylate.

MONOVALENT COMPOUNDS. II7

£ Structure of the Monovalent Alcohols.— The possible
isomeric alcohols may be readily derived from the hydrocarbons ;
they correspond to the mono-halogen isomerides (p. 43). There is '
one possible structure for the first two members of the normal
alcohols : —

CHj.OH C2H5.OH.

Methyl Alcohol. Ethyl Alcohol.

Two isomerides can be obtained from propane, CaHg = CH3.
CHj.CHj : —

CHj.CHj.CHj.OH and CH3.CH(OH).CH3.

Propyl Alcohol. Isopropyl Alcohol.

Two isomerides correspond to the formula C4H10 (p. 74) : —

CH3.CH2.CH3.CHs and CH{CHs)3.
Normal Butane. Isobutane.

Two isomeric alcohols may be obtained from each of these : —

CH3
CH,

CH,

and

CHj.OH
Primary Butyl Secondary Butyl

Alcohol. Alcohol.

CH,

I

CH, /CH3 /CH,

I CH— CHjj.OH and C(OH)— CH,

CH.OH \CH, XCH,

I Prim. Isobutyl Tert. Isobutyl

QTT Alcohol. Alcohol.

The following is a very good method of formulating the alcohols.
They are considered as derivatives of methyl alcohol or carbinol,
CHs.OH. By the replacement of one hydrogen atom in carbinol
by alky Is (p. 46) the primary alcohols result : —

C -

^z^a c H

H I 2^5

H ^^ '

OH CHj.OH

Methyl Carbinol, or Ethyl Carbinol, or

Ethyl Alcohol. Propyl Alcohol.

If the replacing group possesses normal structure, the primary
alcohols are said to be normal. In alcohols of this class the carbon
atom carrying the hydroxyl group has two additional hydrogen
atoms. Hence compounds of this variety may very easily pass into
aldehydes (with group COH) and acids (with COOH group) on
oxidation (see p. 114): —

CH,
and I

COOH

Acid.

CH,

CH,

CHj.OH

yields 1

COH

Primary Alcohol.

Aldehyde

"8 ORGANIC CHEMISTRY.

The secondary akoJwh result when two hydTOgen atoms in
carbinol, CHs.OH, are replaced by alkyls:—

CHj
CH3
H
OH

CH,

I
= CH.OH C-^

CH3

^^8 = CH.OH

Dimethyl Carbinol, or Ethyl-methyl Carbinol, or

tsopropyl Alcohol. Isobatyl Alcohol.

In alcohols of this class the carbon atom carrying the OH group
has but one additional hydrogen atom. They do not furnish
corresponding aldehydes and acids. When oxidized they pass into
ketones (p. 114): —

-CH,

(CHj CHj^

C-l ^^3 yields C|CH3 = '"^CO

OH

(O CHj

Dimethyl Carbinol. Acetone.

When, finally, all three hydrogen atoms in carbinol are replaced
by alkyls, we get the tertiary alcohols : —

CHjX
= CHj— C.OH Trimethyl Carbinol.
CH3/

These are not capable of forming corresponding aldehydes, acids
or ketones. Under the influence of strong oxidizing agents they
suffer a decomposition ; and acids having a less number of car-
bon atoms result.

Primary alcohols, therefore, contain the group CH2.OH joined to
one alcohol radical (in methyl alcohol it is linked to H) ; the
group CH.OH linked to two alkyls is peculiar to secondary alco-
hols; while in tertiary alcohols the C in combination with OH has
three alkyls attached to it : —

R\

R— I

Primary Alcohols, SeCoiTdary Alcohols. ^Z

^^CH.OH R— C.OH

Tertiary Alcohals.

The secondary and tertiary alcohols, in distinction from the pri-
mary or true alcohols, are designated pseudo-alcohols. They
are capable of forming esters (p. 116).

Formation of Alcohols. — The most important methods of pre-
paring the monohydric alcohols are the following : —

(i) The replacement of the halogen of monosubstituted hydro-
carbons by hydroxyl. This is most easily effected by the action of

MONOVALENT COMPOUNDS. II9

freshly precipitated, moist silver oxidd: It acts in this instance
like a hydroxide : —

C.H^I + AgOH = C.Hj.OH + Agl.

In many cases the change is best brought about by heating the halogen deriva-
tives with lead oxide and water ; the formation of alkylens is avoided in this way.
The iodides are more reactive than the chlorides or bromides. Even heating with
water alone at high temperatures causes a partial transposition of halogen into
hydroxy! derivatives. The halogen derivatives of the secondary and tertiary
radicals are very reactive. If heated for some time with I0-15 volumes of water
to 100° they are completely converted into alcohols {Annalen, i85, 390).

Water at ordinary temperatures converts the tertiary alkyl iodides into alcohols.
Heated to 100° with methyl alcohol they pass into alcohols and methyl iodide
{^Annalen, 220, 158).

it is often more practical to first convert the halogen derivatives
into acetic acid esters, by heating with silver or potassium acetate : —

GjHsBr -t- CjHjO.OK = CjHj.O.CjHjO + KBr,
Potassium Acetate. Ethyl Acetic Ester,

and then boil these with potassium or sodium hydroxide (saponi-
fication), and obtain the alcohols : —

CjHj.O.CaHjO + KOH = C^Hj.OH -|- CjHjO.OK.

(2) By decomposing the acid esters of sulphuric acid with boil-
ing water : —

^O.CjHj
SO,/ + H,0 = CJH5.OH + SOiH,.

Ethyl Sulphuric Acid.

These esters may be easily obtained by directly combining the
unsaturated hydrocarbons with sulphuric acid (see p. 8i) : —

C,H, + SOjH, = SO /

A like conversion of unsaturated hydrocarbons is attained by
means of hypoehlorous acid ; the chlorine derivatives first produced
are further changed by nascent hydrogen : —

CH, CHjCl

11 + ClOH =1 , and

CH^ CH,.OH

C,Hp.OH + H, = CjHj.OH + HC1-.

Many alkylens (like iso- and pseudo-butylene) dissolve at once in dilute nitric
acid, absorb water, and yield alcohols {Annalen, 180, 245).

(3) By acting on the aldehydes and ketones with nascent

I20 ORGANIC CHEMISTRY.

hydrogen. The former yields primary, and the latter secondary
alcohols (compare p. ii8) : —

CH3.CHj.CHO + Hj = CH, CH2.CH2.OH,

Propyl Aldehyde. Propyl Alcohol.

CH:>CO + H,= g5)cH.OH.
Acetone. Isopropyl Alcohol.

Sodium amalgam in presence of dilute sulphuric or acetic acid will effect this
reduction. It is, however, best to use iron flings and 50 per cent, acetic acid
(Lieben), or zinc dust and glacial acetic acid; the acetic esters are the first pro-
ducts {^Berickte, 16, 1715).

(4) A very remarkable synthetic method, which led to the dis-
covery of the tertiary alcohols, consists in the action of the zinc
compounds of the alkyls upon the chlorides of the acid radicals.
The product is then further changed by the action of water (But-
lerow). Thus, from acetyl chloride and zinc methyl, we obtain
trimethyl carbinol (CH3)3.C.OH :—

CH3.COCI yields CH3.C(CH3)j.OH.

Acetyl Chloride. ' Trimethyl Carbinol.

The acid chloride (i molecule) is added, drop by drop, to zinc methyl (2 mole-
cules), cooled with ice, and allowed to remain undisturbed for some hours in the
cold, until the ma,ss has become crystalline. After subsequent exposure for two 01
three days, at ordinary temperatures, the product is decomposed with ice water.
Ketones are formed if water be added any sooner {Annalen, 188, 121 u. 113).

The reaction divides itself into three phases. At first only one molecule of zinc
alkyl reacts : —

/,0 (-CH3

(I) CHj.C^ +Zn(CH3)j=CH3CJO.Zn.CH3.

Acetyl Chloride.

The resulting compound gives a crystalline product with the second molecule
of the zinc alkyl, and this immediately decomposed with water yields acetone. By
longer standing, however, further reaction takes place : —

fCH, fCH,

(2) CH3.C \ O.Zn.CH, + Zn (CH3)2 = CHj.C \ O.Zn.CHj + Zn \ )tr
ICl (.CH3 "-^"s-

If now water be permitted to take part, a tertiary alcohol will be formed from
the first body. The equation is : —

fCH, J-CH3

CH3.C -^ O.Zn.CHj + HjO = CH3.C-^ OH -f ZnO + CH,.
ICH3 (CH3

If in the second stage the zinc compound of another radical be employed, the
latter may be introduced, and in this manner we obtain tertiary alcohols witli two
or three different alkyls [Annalen, 175, 261, and 188, no, 122).

MONOVALENT COMPOUNDS. 121

It is remarkable that only zinc methyl and ethyl furnish tertiary alcohols, while
zinc propyl affords only those of the secondary type. (Berickte, i6, 2284.)

(5) Jubt as we obtained tertiary alcohols from the acid radicals, so can we de-
rive secondary alcohols from the esters of formic acid. Zinc alkyls are allowed to
react in this case (or alkyl iodides and zinc), and two alkyls are introduced. At
first crystallinfe intermediate products are produced ; these yield the alcohols when
treated with water : — 0

0.d ■ /CH, /CH,

HC^ ■^ ' yields HC— O.Zn.CH, and HC— OH

^O.CjHj XCHj XCH,

Ethyl Formic Ester. Dimethyl Carbinol.

Using some other zinc alkyl in the second stage of the reaction, or by working with
a mixture of two alkyl iodides and zinc, two different alkyls may also be intro-
duced here (Anna/en, 175, 362, 374).

Zinc and allyl iodide (not ethyl-iodide, however) react similarly upon acetic acid
esters. Two alkyl groups are introduced and unsaturated tertiary alcohols formed
(Annalen, 185, 175): —

^O /C3H, /C,H,

CH,.Cf „ f, „ yields CH,.C— O.Znl and CH-.C— OH

Ethyl Acetic Ester. Methyl-diallyl Carbinol.

When zinc alkyls act upon aldehydes, only one alkyl group enters, and the reaction
product of the first stage yields a secondary alcohol when treated with water.
(Compare Annalen, 213, 369, and Berickte, 14, 2557) : —

CH3.CHO yields CU^.CVl(^^^^ ^ and CHj.CH.C^^^j^s
Aldehyde. ^. //Iji Methyl-ethyl Carbinol.

All aldehydes (even those with unsaturated alkyls, and also furfuran) react in this
way — but only with zinc methyl and zinc ethyl, while with the higher zinc alkyls
the aldehydes suffer reduction to their corresponding alcohols [Berickte, 17, Ref.
318). With zinc methyl chloral yields trichlorisopropyl alcohol, CCl3.CH(0H).
CH3 ; whereas with zinc ethyl it is only reduced to trichlorethyl alcohol [Annalen,
223, 162).

The Ketones do not react with the zinc alkyls. Even in the action of zinc and
ethyl iodide upon such ketones as contain a methyl group, the only result is the
splitting-off of water. On the other hand, diethyl-acetone, (C^HsJ^CO, and
dipropyl ketone, (C3H,)2CO, are converted by zinc and methyl (ethyl) iodide into
zinc alkyl compounds; these, under the influence of water, -pass into alcohols
[Berickte, 19, 60 ; 24, Ref. 35) : —

(C^HJ^CO and zinc ethyl give (C2H5)3C.OH.
Proplone. Triethyl

Carbinol.

(C3H,)2CO and zinc methyl give (C3H,)2.C(CH3).OH.
Butyrone. Dipropyl-methyl

Carbinol.

We get unsaturated tertiary alcohols from all the ketones by the action of zinc
and allyl iodide [Annalen, 196, 113) : —

(CH3),C0 yields (CH3),.(C3H,).C.OH.

Dimethyl Dimethyl-allyl

Ketone. Carbinol.

122 ORGANrC CHEMISTRY.

(6) By the aetioik of haseent hydrogen upon the chlorides of acid ladicftls or
acid anhydiides : —

cttj.cbci + 2b[j = cSj.cHj.OH + kc\,

Acetyl
Chloride.

c'h'0/° + ^^2 = C2H5.6H + C,H,d.OH.

Acetic Acid

AhhydHde.

Very probably aldehydes are pi-bduSed at the bejginhing and are subsequently
reduced to alcohols (see p. 121). Primary alcohols alone result by this reaction.
Sodium amalgam, or better sodium, serves as the reducing agent. {Berichte, 9,
1312.)

(7) Action of nitrous acid upon the primary amines : —

CjHj.NH, + NO.OH = CjHj.OH + Nj -f HjO.

Very often transpositions occur with the higher alkyl-amines and instead of the
primary we obtain secondary alcohols. (Compare Berichte, 16, 744.)

In addition to the above universal methods, alcohols are formed
by various other reactions. Their formation in the alcohohc
fermentation of sugars in the presence of ferments is of great
practical importance. Appreciable quantities of methyl alcohol are
produced in the dry distillation of wood; Many alcohols^ too,
exist, as already formed natural products in toinpeunds> ehiefly as
compound ethers of organic acids;

Cottifersion ef Primary into Secondary and Tertiary Alcohols. By the elimina-
tion of water the primary alcohols beeome unsaturated hydrocarbons Qa Han (p.
79). The latter, treated with concentrated HIj yield iodides of secondary alco-
holic radicals, as iodine does not attach itself to the terminal but to the less hydro-
genized carbon atom (p. 93)1 Secondly alcohols appear when these iodides are
acted upon with silver oxide. The successive conversion is illustrated in the follow-
ing formulas : —

Cxlg Cflg Cxiq Clla

CHj CH CHI CH.OH

I II I I

CH^.OH CH^ CH3 CHj

Propyl Propylene. Isopropyl Isopropyl

AlGdhoi. Iodide. . Alcohol.

Primary alcohols in whicli the group CH2.OH is jojiied to £k secondary radical,
pass in the same manner into tertiary alcohols : —

CH 3 . CH 3 V CH 3 ^

)CH.CHj.OH >C = CHj \ct— CH,
CH3/ CH3/ CH3/

Iscbutyl Alcohol. Isobutylfene. Tertiary Butyl Itidide,

CH,

. )C(OH).CH,
CH3/
Tertiary Butyl Alcohol.

MONOVALENT COMPOUNDS. 1 23

The change is better effected by the aid of sulphuric atid.

The sulphuric esters (p. 80), arising from the alkylens, have the sulphuric acid
residue linked to the carbon atom, with the least number of attached hydrogen
atoms :-^

CH3 CH3

CH + HO.SOj.OH = CH.O.SOjIt.

II I

These pass into alcohols when boiled with water.

Properties and Transpositions. The alcohols are neutral, being
neither acid nor basic compounds. They resemble the bases, in
that by their action with acids they yield esters (compound ethers),
which correspond to salts. In this change, the hydrogen atom of
the OH group is replaced by an acid radical (p. ii6). Na and K
can also replace this hydrogen atom, and then we obtain the metal-
lic alcoholates.

In physical properties alcohols exhibit a |;radation corresponding
to their increase in molecular weight. This is true of other bodies
belonging to hotnologous series. The lower alcohols are mobile
liquids, dissolving readily in water, and possessing the characteristic
alcohol odor ; the intermediate members are more oily, and dissolve
with digiculty in water, while the higher are crystalline solids, with-
out odor or taste. They resemble the fats. Their boiling points
increase gradually (with similar structure) in proportion to the
increase of their molecular weights. This is about 19° for tTie
difference, CH,. The primary alcohols boil higher (about 5°) than
the isomeric secondary, and the latter higher than the tertiary.
Here we observe again that the boiling points are lowered with the
accumulation of methyl groups (see p. 73). The higher members
are not volatile without decomposition. By distillation they pat^
tially break up into water and hydrocarbons CnHj^ (p. 80)1

Oxidizing agents (KjCrO* and H2SO4) convert the primary
alcohols first into aldehydes and then into acids ; those of second-
ary form yield ketones, and the tertiary suffer a partial decom-
position (p. 118). The three varieties of alcohols maybe readily
distinguished by converting them into their iodides and then into the
nitro-derivatives, which afford characteristic color reactions (p. 109).

Primary and secondary alcohols, heated with acetic acid, yield esters of the
latter; the tertiary, on the contrary, lose water and pass into alkylens [Annalen,
220, 165).

The primary alcohols change to their acids when heated with soda-lifltte : —

R.CHj.OH + NaOH = R.CO^H + 2Hj.

This reaction may be employed for the detection and estimation of this class of
alcohols {Annalen, 223, 259).

124 ORGANIC CHEMISTRY.

When the alcohols are heated with the hydrogen haloids, or
what is better, with the halogen derivatives of phosphorus, they
are transformed into their corresponding halogen compounds
(see p. 92) : —

C,H,.OH + HCl = C.HsCl + HjO,
C.Hj.OH +■ PCls = C2H5CI + POCI3 4- HCl.

These derivatives are therefore designated also halogen esters of
the alcohols.

- Hydrogen (nascent) acting on these, causes a change back into
the corresponding hydrocarbons.

Other changes of alcohols will be noted later.

(i) THE ALCOHOLS, Cn Hj„+,.OH.
Methyl Alcohol, CH^O = CH,.OH.

Ethyl "

C,H,0

= CjH^.OH.

Propyl Alcohols,

CsH^O

= C.H,.OH.

Butyl "

C,H.„0

= C^Hg.OH.

Amyl "

C,H,,0

= C.H,,.OH.

Hexyl "

C,Hi,0

= C.Hi,.OH.

Heptyl "

C,Hi,0

= C,Hi5.0H, etc.

Cetyl Alcohol,

C16H34O

= Ci3H33.0H.

Ceryl "

C^H^.O

= C„H,5.0H.

Melissyl «

C3„H,,0

= C3„H3,.OH.

I. Methyl Alcohol, CH3.OH, wood spirit, occurs among the
dry distillation products of wood. We find the methyl group in
various natural products, and from them it may be eliminated in
the form of the above alcohol. Thus methyl alcohol is obtained by
boiling wintergreen oil, the methyl ester of salicylic acid, with potas-
sium hydroxide.

Methyl alcohol is a mobile liquid, with spirituous odor, boiling
at 66° (the apparent boiling point can vary very much, according
to the nature of the vessel), and having a sp. gr. of 0.796 at 20°.
It mixes with water, alcohol, and ether. Its aqueous mixtures
have a sp. gr. almost like that of mixtures of ethyl alcohol and
equal amounts of water.

The aqueous product obtained in the distillation of wood contains methyl alco-
hol, acetone, acetic acid, methyl acetic ester, and other compounds. It is dis-
tilled over burnt lime. The crude wood spirit that results contains acetone as its
chief impurity. To remove this add anhydrous calcium chloride. The latter
combines with the alcohol to a crystalline compound. This is removed, freed
from acetone by distillation, and afterward decomposed by distilling with water.
Pure aqueous methyl alcohol passes over; this is dehydrated with lime. To pro-

THE ALCOHOLS. 1 25

cure it perfectly pure, it is only necessary to break up oxalic methyl ester, or methyl
acetic ester, with KOH.

To detect ethyl in methyl alcohol, heat the latter with concentrated HjSO^,
when acetylene will be formed from the first. Under this treatment, methyl
alcohol becomes methyl ether. The amount of methyl alcohol in wood spirit is
determined, quantitatively, by converting it into methyl iodide, CHgl, through
the agency of PI, {Berickte, g, 1928). We estimate the quantity of acetone by
the iodoform reaction {Berichte, 12, 1000).

Wood spirit is employed as a source of heat, and as a solvent
for gums and resins. It combines directly with CaClj, to form
CaCl2.4CHiO, crystallizing in brilliant six-sided plates. The
alcohol in this salt conducts itself like water of crystallization.
Potassium and sodium dissolve in anhydrous alcohol, to form
methylates, e. g., CHj.ONa (see sodium ethylate, p. 126). Barium
oxide dissolves in it to yield a crystalline compound (Ba0.2CH40).
When methyl alcohol is heated with soda-lime, sodium formate
results : —

CH3.OH + NaOH = CHO.ONa + 2Hj.

Oxidizing agents and also air, in presence of platinum black, change
methyl alcohol to formic aldehyde and formic acid.

2. Ethyl Alcohol, C2H5.OH, may be obtained from ethyl
chloride, C2H5CI, and from ethylene, C,!!,, by the general methods
previously described (p. 119). Its formation in the spirituous fer-
mentation of different varieties of sugar e.g., grape sugar, invert
sugar, maltose — is practically very important. It is induced- by
yeast cells, occurs only in dilute aqueous solution at temperatures
ranging from 5-30°, and demands the presence of mineral salts
(especially phosphates) and nitrogenous substances (compare Fer-
mentation). Alcoholic fermentation may set in under certain con-
ditions, in ripe fruits, even in the absence of yeast. The various
sugars, when fermenting, break up principally into ethyl alcohol
and carbon dioxide : —

CeHijOj = 2C2HO, + 2CO2.

Glucose.

Other compounds, like propyl, butyl and amyl alcohols (the fusel
alcohols), glycerol, and succinic acid, are produced in small quanti-
ties at the same time.

The crude spirit obtained from the fermented aqueous solution (of the fer-
mented mash) by distillation is further purified on an extensive scale by fractional
distillation in a column apparatus (p. 59). The first portion of the distillate con-
tains the more volatile bodies, like aldehyde, acetal and other substances. Next
comes a purer spirit, containing 90-96 per cent, alcohol, and after this common
spirit, containing the fusel oils. To remove the latter entirely, the spirit, before
distillation and after dilution with water, is filtered through ignited wood,^ charcoal,
which retains the fusel oils. V

126 ORGANIC CHEMISTRY.

To prepare anhydrous alcohol, the rectified spirit (9095 per cent, alcohol) is
distilled with substances having greater attraction for water than alcohol itself.
For this purpose calcium chtoride^ ignited potashes, or, better, caustic Hme
(Anaakn, 160, 249), or barium oxide may be employed. Absolutfl alcohol dis-
solves barium oxide, assuming a yellow color at thie saime time. It is soluble
without tiurbidity iu a little benzene; when more than three per cent, water is
present cloudiness ensues. On adding anhydrous or absolute alc<Aol to a mix.
ture of very little anthraquinone and some sodium aanajgam it become* ienk green
in color, but in the presence of traces of water a red coloration appears (Berichte,
10,927). Traces of alcohol in solutions are detected and determined either by
oxidation to aldehyde (see this) or by converting it by means of dilute potash anid
iodine into iodoform {Berickte, 13, 1002).

Its conversion into ethyl benzoate, by shaking with benzoyl chloride and sodium
hydroxide {Berichte,, 19, 321,8), afee answers for this purpose-
Absolutely pure aleohol possesses an agreeable etheieal. odor,
boils at 78.3°, and has a specific gravity of 0,80625 at o'*^ or
o- 78945 at 20°-. At -^90° it is a thick liquid, at — 130° it solidi-
fies to a white mass. It absorbs water energetically from the air.
When mixed with water a contraction occurs, accompanied by rise
of temperature^ the maximum is reached when one molecule of
aleohol is mixed with three molecules of water, corresponding to
the formula, QHbO -f 3H2O. The amount of alcohol in aqueous
solutions is given either in per cents, by weight (degrees according
to Richter) or volume per cents, (degrees according to Tralles).

Alcohol dissolves many mineral salts, the alkatRes, hydrocarbons,
resins, fatty acids, and almost all the carbon derivatives. The most
of the gases are more readily soluble in it than in water ; roo
volumes of alcohol dissolve 7 volumes of hydrogen, 25 volumes of
oxygen, and 13 volumes of nitrogen.

Ethyl alcohol forms crystalline compounds wtth some salts, like
calcium chloride and magnesium chloride. It plays the. r61e Qf
water of crystallization in them.

Potassium and sodium dissolve in it (also in all other alcohols}, sepaarat&ig
hydrogen from the hydroxyl group and yielding the. so-called metallic alcoholates,
e.g., CjHj.ONa. AH the alcohol cannot be thus changed; on evaporating the
excess, white crystalline compounds, CjH 5. ONa or CjHj.OK, having two and
three molecules, of alcohol,, remain. The alcohol does not escape until the com-
pounds aiie heated to 200° ; then the residual alcoholates form a white, volumi-
nous powder. (Consult Berichte, 22, loir, on the preparation of sodium alco-
holate.) Excess of water converts them into alcohol and sodium hydroxide.
When but little water is employed, the transposition is only partial. Hence the
ethylates are also formed in dissolving KOH and NaOH in strong alcohoh Other
metallic oxMes^ ^g-, bariium oxide, yield similair derivatives. When aluminium
and iodine act upon ethyl and other alcohols, aluminium alcoholates, e.g^, atemim-
ium ethylate, Al^'OC^H'^)), result; these can be distilled in vacuo.

Oxidizing agents (MtiO^ and' HjSO^, chromic acid, pla^tiflium
black and air) convert ethyl alcohol into acetaldel^ydie. aad acetic

THE ALCOHOLS., 127

aeid. Nitric acid changes it at 20-30° iatQ glyoxal, glyoxalic
acid, glycollic acid and oxalic acid. When acted upoa by chlorine
and bromine, chloral and bromal (CCI3.CHO and CBrj-CHO) are
produced.

The wo»<»-substituted alcohols^ CHjX.CHj.OH, will be described as halogen-
hydrins UQder the glycpls. ,

Trichlor-Ethyl Alcctbol, CCl^.CHj.OH, resulting from the action of zijie
ethyl upon chloral, consists of white rhombic crystals, fusing at 17.8° and boiling
at 151°; specific gravity 1.55, at 23°. It is sjightly soluble in water, but readily
splu,ble in alcohol and ether. When oxidized with nitric acidj it yields trichlor-
apetic acid {A^tmalen, 210,, §3).

Nitro-Ethyl Aicohol, CH2(N02).CHj.OH, is prepared in a manner similar
to those employed for the nitro-paraffins — by the action of silver nitrite upon
ethylene-iodhydrin.CHjI.CHj.QH. It forms an oil miscible with water. It
yields a beautiful sodium salt, and is capable of forming azo-dyes (Berichte, 21,
3529; Annalen, 256, 28).

3, Propyl Alcohola, CsH^.OH:^

CP3,CH2.CHj.OH CH,.,CH(OH)— CH,.

Propyl Alcohol, Isopropyl Alcohol.

(i) Normal Propyl Alcohol, CH3.CHj.CH2. OH, is produced
in the fermentation of sugars, etc. It may be obtained from fusel
oil by fractionjd distillation (p. 125). To get it perfectly pure, the
corresponding bromide is converted into the acetate,, and this
broken up by potassium bydf oxide. It may be artificially prepared
from propyl aldehyde and propionic ?bnh,ydride. by the action of
nascent hydrogen (sodium amalgam). It is an agreeable-smelling
liquid of specific gravity 0,8044 at 20°, and boijing at 97.4°. The
boiling point is very materially affected by slight additions of water,
as a hydrate, CaHgC-f H2O,, is formed, which boils at 87°. It is
miscible in every proportion with water, but on the addition of
calcium chloride and other easily soluble salts, it separates again
from its aqueous solution. Hence it is in^soluble in a saturated,
cold calcium chloride soljition,. and this distinguishes it firom ethyl
alcohol.

It passes into propionic aldehyde and; propionic acid,, under the influence of
oxidizing agents. When heated "with 5 volumes of H^SO^, it yields propylene.
Its chloride, boils at 46.5°-, the bromide at 71°, the iodide ^\ 102° (p. 96).

(2) Secondary or Isopropyl Alcohol-, (CH3)a,CK.0H,
dimethyl carbinol, is prepared from, the isoriodide (p. 96)= ; fiom
acetone ('CH3)2.C(>, by the action of sodium amalgam ; from acro-
lein, C3H4O, propylene oxide, CsHgO, and dichtorhydrin, CsHjClv.
OH, by means of n^cent hydrogen; froni glycol iodhydrin,
CjHJ.OH, by section of zinc methyl ; from propylamine (p. 122)

IZ8 ORGANIC CHEMISTRY.

by action of nitrous acid, and from formic ester by the aid of zinc
and methyl iodide (p. 121).

Preparation. — A mixture of one volume acetone and five volumes of water is
shaken with liquid solium amalgam, and the distillate repeatedly subjected to the
same treatment, until an energetic liberation of hydrogen is perceptible. It is then
distilled, the distillate dehydrated with ignited potashes and afterwards mixed with
pulverized calcium chloride. The resulting crystalline co npound is deprived of
all adhering acetone by standing over sulphuric acid. If heated, it breaks up into
CaClj and isopropyl alcohol.

The most practical method of obtaining it is to boil the iodide with ten parts of
water and freshly prepared lead hydroxide in a vessel connected with a return
condenser, or simply by heating the iodide with twenty volumes of water to 100°
{Annalen, 186, 391).

Isopropyl alcohol boils at 82.7°, and has a specific gravity 0.7887
at 20°. It is miscible with water, alcohol and ether ; potash will
separate it again from the aqueous solution. Oxidizing agents
convert it into acetone. Its chloride, CsHjCl, boils at 37°, the
bromide at 60-63°, and ^^ iodide at 89° (p. 96). The benzoic
ester, C3H,O.C7H50, breaks up on distillation into benzoic acid
and propylene.

CCI3

Trichlorisopropyl Alcohol, ^CH.OH, is produced in the action of

CH,/
zinc methyl on chloral. It is crystalline, fuses at 49°, and boils about iSS°
(Annalen, 210, 78).

4. Butyl Alcohols, C^Hg.OH. According to theory four isomerides are
possible : 2 primary, i secondary, and I tertiary (p. 117): —

CrT,.CHo.CH«

:. , 2. ?^<ch:

CHj.OH CHj. OH

. Isobutyl Alcohol.

Normal Butyl Alcohol. Isopropyl Carblnol.

Propyl Carbinol.

3. '\ciI.OH 4. (CH3)3.COH

CH,.CH/ Trimethyl Carbinol.

Methyl-ethyl Carbinol.

(i) Normal Butyl Alcohol, CjHj.CH^.OH, forms in the [action of sodium
amalgam upon normal butyl aldehyde, CjH^.COH, upon butyryl chloride,
CjH,. CO. CI, and upon butyric anhydride. It is further produced by a peculiar
fermentation of glycerol, brought about in the presence of a schizomycetes
(Berichte, 16, 1438). It is prepared most readily in this way. It is a liquid with
an agreeable odor, has a sp. gr. of 0.8099 ^' 20° and boils at 116.8°. It is soluble
at 22° in 12 volumes of water. Calcium chloride and other salts separate it again
from its solution. When oxidized it passes into butyl aldehyde and butyric acid.
Its chloride, CjHf .CHjCl, boils at 77.6°, the bromide at 99.8°, and the iodide at
120°.

Trichlorbutyl Alcohol, CHj.CHCl.CClj.CH^.OH, results when zinc ethyl
and butyl chloral (see Trichlor-ethyl alcohol, p. 127) are brought together. It

THE ALCOHOLS. 1 29

crystallizes in prisjns, fuses at 62°, and boils under 45 mm. pressure at 120°. If
oxidized with nitric acid it yields trichlorbutyric acid {Annalen, 213, 374).

(2) Isobutyl Alcohol, CsHj.CH^.OH, butyl alcohol of fermen-
tation, occurs in several fusel oils and especially in the spirit from
potatoes. It is a liquid possessing a fusel-oil odor, has a sp. gr. of
0.8020 at 20° and boils at 108.4°. It is soluble in ten parts of water,
arid is again separated from solution on the addition of salts. When
oxidized it affords isobutyric acid. Its chloride, CiHgCl, boils at
69°, the bromide at 92°, and the iodide at 121°. When the bromide
is heated to 240° it is converted into tertiary butyl bromide ; very
probably (CH3)2.C:CH2 forms at first, and subsequently yields
(CH3)3CBr with HBr (p. 94).

When isobutyl alcohol is heated with HCl, HBr or HI there result, in addition
to the normal halogen esters, also those of trimethyl carbinol, (CH3)3CX,
because isobutylene, (CH3)2.C;CH2, is produced from the former, and this then
combines with the halogen hydrides to compounds of the type (CH3)2.CX.CH3
(see p. 122).

CH3.

(3) Methyl-ethyl Carbinol, )CH.OH (Butylene Hydrate), is obtained

from its iodide, produced by heating erythrite with hydriodic acid (p. 95) ; the
same iodide is also formed from normal butylene (pp. 84 and 122). The alcohol
may further be made by treating formic ester with Zn and CH3I and C2H5I;
and from the dichlor-ether, CHjCl.CHCl.O.CaHj, (see Ether) by the aciion of
zinc- ethyl and HI. It is a strongly smelling liquid, boiling at 98°-ioo°. Its sp.
^. at 0° is 0.827. Heated to 240°-2So° it decomposer into water and /3-butylene,
CHa.CH:CH.CH3. (Compare Berichte, 19, Ref. 610I. It yields methyl-ethyl

CH3.
ketone, ^CO, when oxidized. Its iodide boils at 119-120°.

C H "^

{4) Trimethyl Carbinol. {CH3)3.C.OH, ferfta?^ butyl alcohol, is found in
small quantities in fusel-oil, and arises in the action of acetyl chloride upon zinc
methyl (p. 120). It can also be obtained from the butyl alcohol of fermentation
by means of isobutylene (p. 122). _

When perfectly anhydrous it crystallizes in rhombic prisms or plates, fusmg at
28° and boiling at 83-84°. Its sp. gr. at 30° is 0.7788. It is miscible with water
in all proportions, forming the hydrate, iC^l^-^^O + HjO, which crystallizes m a
freezing mixture, and boils at 80°. When oxidized with chromic acid it yields
carbon dioxide, acetic acid, acetone, and a little isobutyric acid.

Its chloride, CiHgCl, boils at 50-51°, and the iodide at 99°. When the latter
is heated with zinc and water trimethyl methane, CgHm, and isobutylene,
C H. = (CH3),C:CH2, result. On combining the latter with ClOH,
(CH3)2CCI.CH2.0H will be formed ; nascent hydrogen converts this into isobutyl
alcohol, (CH3)2.CH.CH2.0H.

(5) Amyl Alcohols, CjHu.OH. Theoretically 8 isomerides are possible: 4
primary alcohols, 3 secondary, and I tertiary : —

II

13° ORGANIC CHEMISTRY.

CH,-CH,-CH3 CH,-CH<gl[^»

Primary: I. I 2. | '

CH,— CH-.OH CHj.OH

.C,H, C(CH3)3

^«<ck? 4.

CHj.OH

C,H,, CH

CH,.OH

Secondary: 5. ' '^CH.OH 6. '^.CH.OH

C,h/ C3H/

CH3.
7. )CH.OH

C VI ^

CHg.CHjX

Tertiary: 8. CH3— C.OH.

CH3/

( i) Normal Amyl Alcohol, C^H 9 .CHj .OH (contains the normal butyl group),
is obtained from valeraldehyde and from normal pentane. It is most easily prepared
from normal amylamine (from caproic acid) by the action of nitrous acid (p. 122, and
Annalen, 233, 252). It is almost insoluble in water, has a fusel-oil odor, and boils at
137°. Itssp. gr. at 20° equals 0.8 1 68. On oxidation it yields normal valeric acid.

Its chloride bo\\s 3.1 106-107° ^-i it is produced (together with C3H,.CHC1.CH3)
in the chlorination of normal pentane. The bromide boils at 129°, and the iodide
at 155.5°

(2) Isobutyl Carbinol, (CH3)jCH.CH2.CH2.0H (Inactive
amyl alcohol, isopentyl alcohol), constitutes the chief ingredient of
the amyl alcohol of fermentation obtained from fusel oil (p. 125),
and occurs as esters of angelic and tiglic acids in Roman camo-
mile oil. It may be obtained in a pure condition by synthesis from
isobutyl alcohol, (CH3)j.CH.CH2.0H, by converting the latter
into the cyanide, the acid, the aldehyde, and finally into the alco-
hol. It boils at 131.4°, and its sp. gr. at 20° is 0.8104. At 13° it
dissolves in 50 parts water. Its chloride, C5H11CI, boils at 100°,
the bromide at 120.4°, and the iodide at 148°. When oxidized it
yields inactive valeric acid.

The so-called alcohol of fermentation, possessing a disagreeable
odor and boiling at 129-130°, occurs in fusel oil and consists
mainly of inactive isobutyl carbinol. In addition, methyl-ethyl
carbinol (active amyl alcohol) and probably, too, normal amyl
alcohol are present. It rotates the plane of polarization to the left ;
its activity is due to the presence of active amyl alcohol. The
latter distils over first when fusel oil is thus treated.

Fermentation amyl -alcohol, treated with sulphuric acid, yields two amyl-
sulphuric acids. The different solubilities and crystalline forms of their barium
salts distinguish them. From the more sparingly soluble Salt, which forms in
rather large quantity, isobutyl carbinol may be obtained by boiling its acid with
water. Active amyl alcohol is prepared from the more readily soluble salt. The

THE ALCOHOLS. I3I

first alcohol yields inactive valeric acid on oxidation, the second the active acid.
A more complete separation of the alcohols is reached by conducing HCl into
the mixture. Isobutyl carbinol will be etherified first, the active aniyl alcohol re-
miining (Le Bel) [Annalen, 220, 149). When the crude fermentation alcohol is
distilled witlj zinc chloride ordinary amylene is the product. This consists mainly
of (CH3)jC:CH.CH3, resulting from a transposition of isobutyl carbinol; it con-
tains, besides, y-amylene and a-amylene (compare p. 84). The iodide of the fer-
mentation alcohol is made up principally of (0113)2. CH.CHjI ^""^
CH3-

JiCH.CHjI, and yields the amylenes, (€113)2. CH.CHiCH^ and

CH3.

>C:CH2 (p. 8s).

CH3

(3) Active Amyl Alcohol, ^CH.CHj.OH, secondary butyl carbinol,

methyl-ethyl carbinol, is the active ingredient (about 13 per cent.) of the fermen-
tation alcohol, and may be separated from this by the method above described.
It boils at 127°. In accordance with its asymmetric structure (p. 63) it is
optically inactive and is indeed lievo-rotatory [a] 6 = 4.4°. Its chloride,
C5H11CI, boils from 97-99°, the bromide from 117-120°, and the iodide ixoxa
144-145°. These are all optically active. The same may be noted in regard
to ethyl amyl and diamyl obtained from the iodide. Those derivatives, on the
contrary, not containing an asymmetric carbon atom, are inactive, e, g., amyl

CH3, CH3

hydride, "^CH.CHs, and y-amylene, ^CiCHj (p. 63 and Annalen,

C,n/ C2H/

CH3,
220,157). Active valeric acid, JCH.COjH, results from the oxidation of

active amyl alcohol.

Active amyl alcohol becomes inactive on boiling with NaOH, otherwise it
manifests all the properties of the active modification. A mucor will render it
again active, but dextro-rotatory {Berichte, 15, 1506).

(4) Tertiary Butyl Carbinol, (CHg)3.C.CH2.0H, has not yet been obtained,
but no doubt may be prepared from tertiary butyl alcohol through the cyanide
(as in the case of isobutyl carbinol).

(5) Diethyl Carbinol, (C2H5)2.CH.OH, is formed by the action of zinc and
ethyl iodide upon ethyl formate (p. 121). It boils at 116-1 17°, and has a specific
gravity at 0° of 0.832. Its iodide boils at 145°, and the acetate at 132°.
;8-Amylene (p. 84) is obtained from the iodide. Diethyl ketone, (€2115)200,
results from the oxidation of the alcohol. Since ^-amylene, C2H5.CH:OH.OH3,
yields O2H5.CH2.OHI.CH3 with HI, from which methyl normal propyl carbinol
is obtained, we can in this manner convert the diethyl carbinol into the latter

alcohol.

CH3.

(6) Methyl Normal Propyl Carbinol, ^CH.OH.is formed from methyl

3 7

propyl ketone by the action of nascent hydrogen. It may be obtained, too, frotn
\\i&iodide, 0,H,.CHI.0H3 (from a- and ;3-amylene, see above) and the chlonde
C H CHCl.CH. (from normal pentane). It boils at 118.5°. Its sp. gr. at 0° is
o 824 lis iodide boils at 144-145°. and the chloride at 103-105°. Methyl

132 ORGANIC CHEMISTRY.

normal propyl ketone is the oxidation product of the alcohol. The iodide yields
/3-amylene.

CH3.

(7) Methyl Isopropyl Carbinol, )CH.OH, is obtained by the action of

sodium amalgam upoit an aqueous solution of the corresponding ketone. It is an
oil with a fusel odor, boils at 112.5°, ^"^ ^^^ " sp. gr. at 0° of 0.833. When
oxidized it yields methyl isopropyl ketone.

When acted upon by halogen hydrides and also PCI5, the derivatives of the
CH3.
type, ^CHX, do not form, but, in a singular manner, those of tertiary amyl

c,h/

alcohol : — pjt

'^CH.OH yields (CH3)2CX.CH2.CH3.
(CH3),CH/

Very probably amylene, (CHjjjCiCH.CITj, is the first product, and this by
addition of the halogen hydrides yields the derivatives of tertiary amyl alcohol
(compare p. 122).

The real derivatives of methyl-isopropyl-carbinol are obtained from o-isoamy.
lene, (CH3)2.CH.CH:CH2 (p. 84), by the addition of halogen hydrides at ordinary
temperatures or when warmed. The resulting iodide, (CH3)2.CH.CHI.CH3,
boils at 137-139°, the bromide at 114-116°, and the chloride at 91°. The iodide
yields /J-isoamylene, (CH3)2C:CH.CH3.

(8) Tertiary Amyl Alcohol, '^^^^ j C.OH, Dimethyl-ethyl-carbinol, Amy-
lene hydrate. This is synthetically prepared by the action of zinc methyl on

propionyl chloride. It may be obtained from y-amylene, ^CiCHj, and

r H '
^-isoamylene, (CH3)2C:CH.CH3, when their HI compounds are heated with lead
oxide and water. Since ordinary amylene consists chiefly of /3-isoamylene (p. 85),
tertiary amyl alcohol is most practically prepared from the first by shaking it with
sulphuric acid and boiling the soluiion with water [Anna/en. 190, 345).

Tertiary amyl alcohol has an odor like that of camphor, boils at 102.5°, solidifies
at — 12.5° and melts at — 12°. Its specific gravity at 0° is 0.827. Its iodide boils
at 127-128°, the bromide at 108-109°, ^^^ tl^^ chloride at 86°. At 200° it
decomposes into water and ^isoamylene. Acetic acid and acetone are its oxida-
tion products.

6. Hexyl and Caproyl Alcohols, CjHjg.OH. Seventeen isomerides are
theoretically'possible: 8 primary (as there are eight amyl radicals), 6 secondary,
and 3 tertiary. Of the eight known at present there may be mentioned :—

(I) Normal Hexyl Alcohol, CH3.(CH2)4.CHj.OH. This was first obtained
(together with methyl butyl carbinol) from normal hexane. It can be prepared
pure from caproic acid, CgHj^Ojjby reduction, and by the transformation of hexyl-
amine (from cenanthylic acid, C,Hj^02, Berichte, 16, 744). Hexyl butyrate
occurs in the volatile products of some j^rac/faffz varieties (together with octyl
acetate). The alcohol may be obtained from these by saponification with caustic
potash. It boils at 157°, and has a specific gravity at 23° of 0.819. Normal
caproic acid is its oxidation product. The iodide, CgHjjI, boils at 180°, and the
chloride, CjHijCl, at 130-133°.

(2) Methyl-tertiary Butyl Carbinol, (CH3)3.C.CH.OH.CH3, Pinacolyl alco-
hol. Nascent hydrogen acting on pinacoline (see this) produces the above

THE ALCOHOLS. 1 33

alcohol. When cooled it crystallizes and melts at -|-4°. It boils at 120°, and has
a specific gravity of 0.834. If oxidized with a chromic acid mixture it first yields

(CH3)3C

the ketone, /CO, finacoline, which afterwards breaks up into carbon

CH3/
dioxide and trimethyl acetic acid.

(3) Fermentation Hexyl Alcohol or Caproyi Alcohol, CgHjj.OH, is found
in the fusel oil of grape spirit. It boils at 150°. Its constitution is not well deter-
mined. That it is a primary alcohol is evident from the fact that when it is oxid-
ized it changes to caproic acid.

7. Heptyl or CEnanthyl Alcohols, CjHjj.OH. Thirteen of the thirty-eight
possible isomerides are known. The following may be noticed : —

(1) Normal Heptyl Alcohol, CH3(CH2)5.CH2.0H, from oenanthyl aldehyde
(Anna/en, 200, 102) and normal heptane, boils at 175° and yields normal cenan-
thylic acid on oxidation.

(2) Dimethyl-tertiary Butyl Carbinol, C(CH3)3.C(CH,)2.0H, or Penta-
methyl ethyl alcohol, obtained from trichlor-meihyl acetic anhydride, C(CH,)3.
COCI, by means of zinc methyl, melts at -f- 17° and boils at 131-132°. It yields
a crystalline hydrate, 2C,Hi50 + Hfi, with water. This melts at 83°. Its
chloride boils at 136°, and the iodide at 141°.

The following higher normal alcohols are known : Octyl, cetyl, ceryl, and melis-
syl alcohols occur naturally as esters; the others are obtained from the correspond-
ing aldehydes by reduction (p. 120).

Octyl Alcohol, CjHjgO, occurs as octyl acetate in the volatile oil of Heracleutn
spondylium, as butyrate in the oil of Pastinaca sativa, and together with hexyl
butyrate in the oil from Heradeum giganteum. It boils at 190-192°, and at l6°
it has a sp. gr. = 0.830, Caprylic acid is its oxidation .product.

Decyl Alcohol, CjjHjj.OH, from capric aldehyde, melts at -|-7°, and under 15
mm. pressure boils at 43.5°.

Dodecatyl Alcohol, Cj^Hj^.OH, from lauraldehyde, melts at 24°, and boils
at 119° under a pressure of 15 xa'ca.

Tetradecatyl Alcohol, CijHjj.OH, from myrisitaldehyde, melts at 32°, and
under a pressure like that given with tlie preceding compounds boils at 167°.

Cetyl Alcohol, C16H33.OH, Hexadecyl Alcohol, .formerly
called ethal, is prepared from the cetyl ester of palmitic acid, the
chief ingredient of spermaceti, by saponification with alcoholic
potash : —

\0 + KOH = C,eH33.0H -f q.Hj.O.OK.
/ Etbal. Potassium

Ethal.

Palmitale.

It may also be obtained in a pure condition by the reduction of
palmitic aldehyde, whereas when prepared from spermaceti it is
contaminated with octodecyl alcohol {Berichte, 17, 1627).

Ethal is a white, crystalline mass fusing at 49-5°' ^"^ distilling
about 340° with scarcely any decomposition (under 15 mm. pressure
it boils at 189°). It yields, when fused with potassium hydroxide,
palmitic acid.

Octodecyl Alcohol, CisHji-OH, from stearaldehyde, fuses at 59°, and boils at
210° (under 15 mm.).

134 ORGANIC CHEMISTRY.

Ceryl Alcohol, C27H55.OH— CVw/i«— as ceryl cerotic ester,
constitutes Chinese wax. It is obtained by melting the latter with
caustic potash :-r-

" "" \0 + KOH = C^Hjj.OH + C„H,30.0K.
r H / Cerotin. Potassium

"-2l"55 Cerotate.

Ceryl alcohol is a white, crystalline mass, fusing at 79°. It yields
cerotic acid when fused with potassium hydroxide.

Melissyl Alcohol, CsoHsi.OH, myricyl alcohol, occurs as
myricyl palmitate in beeswax. It is isolated in the same manner as
the preceding compound, and melts at 85°. Its chloride melts at
64°, and the iodide at 69.5°.

2. UNSATURATED ALCOHOLS, CnH:,„_,.OH.

These are derived from the unsaturated alkylens, CnHj^, in the
same manner as the normal alcohols are obtained from their hydro-
carbons. In addition to the general character of alcohols they are
also capable of directly binding two additional affinities.

The lowest member of the series — the so-called vinyl alcoAol— C^H^. OH =
CHj.-CH.OH, appears to exist in ordinary crude ether {Berichte, 22, 2000), but
cannot be prepared artificially, because in all the reactions in which it should form,
flie isomeric acetaldehyde, CH3.CHO, is produced. It seems to be the universal
rule, that the atomic grouping = C-.CH.OH, in the act of formation, is transposed
into = CH.CHO, as aldehydes result instead of the expected secondary alcohols.
The group C.C(OH:CH2 (with tertiary alcohol group) passes over into C.CO.CH3,
since ketones are always produced (compare acetone).* These facts explain many
abnormal reactions (compare Berichte, 13, 309, and 14, 320). The same rule holds
good for the unsaturated oxy-acids in free condition, but does not apply to their
sails and esters {Berichte, 16, 2824). When the' allyl alcohols are oxidized with
potassium permanganate they yield triatomic glycerols (p. 82).

I. Allyl Alcohol, C3H5.OH = CH2:CH.CH,.0H. This may
be prepared by heating allyl iodide to 100° (p. 99) with 20 parts
water. It is produced, also, when nascent hydrogen acts upon
acrolein, CH^iCH.COH, and sodium upon dichlorhydrin. CHjCl.
CHCI.CH2.OH. It is best prepared from glycerol by heating the
latter with formic or oxalic acid.

Preparation. — A mixture of four parts glycerol and I part crystallized oxalic
acid, with addition of ^ per cent, ammonium chloride, is slowly heated to 100° in
a retort. Carbon dioxide is disengaged, while formic acid and some allyl alcohol

* The two isomeric forms are probably tautomeric (see p. 54) .

UNSATURATED ALCOHOLS.

135

pass over. When the liberation of gas has ceased somewhat, the heat is raised to
200°, and the distillate collected. The latter contains, besides ally] alcohol, some
allyl formate and acrolein. To further purify it the distillation is repeated, the
product warmed with KOH and dehydrated by distillation over barium oxide
[Annalen, 167, 222).

In this reaction the oxalic acid at first breaks up into carbon dioxide and formic
acid, which forms an ester with the glycerol; this then decomposes into allyl alco-
hol, carbon dioxide, and water : —

•"'''l /-; ,A^ CHj.O.CHO CH„

y^r^^XM>0 I II '

u,^+ .uc3«i.Wv CH.OH'*""*''^=CH +*C0, + H20.

CH,.OH (in^.OH

By this method 20-25 per cent, of the glycerol is changed to allyl alcohol.

Allyl alcohol is a mobile liquid with a pungent odor, boiling at
96-97°, and having at 20° a specific gravity of 0.8540. It solidifies
at — 50°. It is miscible with water and burns with a bright flame.

It yields acrolein and acrylic acid when oxidized with silver
oxide, and only formic acid (no acetic) when chromic acid is the
oxidizing agent. Nascent hydrogen is apparently without effect
upon it; when heated to 150° with KOH formic acid, normal
propyl alcohol and other products are obtained.

For the halogen esters of allyl alcohol see page 98.

It combines with Cl^ and Brj to form the /3-dichlorhydrins of glycerol (see these).
The monosubstituted allyl alcohols are represented by two isomerides : —

CH2:CC1.CH2.0H and CHChCH.CH^.OH.

a-Chlorallyl Alcohol. /3-Chlorallyl Alcohol.

The first of these is formed from a-dichlorpropylene, CHjiCCLCH^Cl, on
boiling with a sodium carbonate solution; it boils at 136°. When it is dissolved
in sulphuric acid and distilled with water it becomes acetone alcohol, CH,.CO.
CHj OH.

/S-Chlorallyl Alcohol, from ;3-dichlorpropylene, CHChCH.CH^CI, boils at
153°, and causes painful blisters.

^-Bromallyl Alcohol, CHBriCH.CH^.OH, from ^-dibrompropylene, boils at
152°, and yields propargylic alcohol with KOH.

2. Crotyl Alcohol, C4H,.OH = CH3.CH:CH.CH2.0H, is obtained from
crotonaldehyde, CHj.CHiCH.CHO, by means of nascent hydrogen. It boils at
117-120°.

3. Higher unsaturated alcohols of the allyl series, having tertiary structure,
arise in the action of zinc and allyl iodide upon ketones and in the decomposition of
the resulting product with water (p. I2i).

(3) UNSATURATED ALCOHOLS, CnH^-j.OH.

Propargyl Alcohol, CaHiO = CHiC.CH^.OH, is the only
known alcohol of the acetylene series. There is a triple union of
two carbon atoms present in this compound. It is produced on

136 ORGANIC CHEMISTRY.

heating /S-broraallyl alcohol (see above) with potassium hydroxide
and water: —

CHBrrCH.CHj.OH yields CH : C.CHj.OH.

Propargyl alcohol (or propinyl alcohol) is a mobile, agreeable-
smelling liquid, with a sp. gr. at 20° of 0.9715. It boils at 114-
115°, and dissolves readily in water. With an ammoniacal cuprous
chloride solution (p. 87) it forms a yellow precipitate, (QHj.
OH)2Cu2, from which the alcohol is again set free by acid. Silver
solutions produce a white precipitate, CsHjAg.OH.

Trichloride of phosphorus converts the alcohol into the chloride, C3H3CI.
This boils at 65°. Ths bromide, CjHgBr, formed by PBr,, boils at 88-90°; the
iodide boils at 115°. The acetate, CjHj.O.CjHjO, results when acetyl chloride
acts upon the alcohoL Its boiling point is 125°.

Ethyl- Propinyl Ether, C3H3.O.C2H5, is made from glyceryl bromide,
CjHjBrj, and the various dichlor- and dibrom-propylenes, CgH^Br^, by the
aid of alcoholic potash. It is a liquid with a penetrating odor, of sp. gr. 0.8326
at 20°, and boils at 80°. Its copper compound, (C3H2.0.C2H5)2Cu, is yellow
colored, while that with silver, CjHjAg.O.CjHg, is white.

Higher alcohols, in which the double union of carbon atoms occurs twice, are
produced by the action of zinc and allyl iodide upon ethers of formic acid and even
of acetic acid, whereby secondary and tertiary alcohols result (p. 120). These
alcohols absorb four bromine atoms, but do not, however, enter into combination
with copper and silver. This accords with their structure.

ETHERS.

The oxides of the alcohol radicals are thus designated. In the
ethers of the monohydric alcohols two alkyls are present, joined to
each other by an oxygen atom. They may be considered also as
anhydrides of the alcohols, formed by the elimination of water from
two molecules of alcohol : —

CjHj.OH + C^H^.OH = ' °\0 + H2O.

Ethers containing two similar alcohol radicals are termed simple
ethers ; those with different radicals, mixed ethers : —

C2H5, C2H5,

C2H5/ CH3/

Ethyl Ether, or Methyl-ethyl

Diethyl Ether. Ether.

We m.ust make a distinction between the above and the so-called

ETHERS. j,»

compound ethers or esters, in which both an alcohol radical and an
acid radical are present, e. g. , —

CjHj

\r

>0 Ethyl Acetic Ester.

The properties of these are entirely different from those of the
alcohol ethers. In the following pages they will always be termed
esters.

The following are the most important methods of preparing

1. Action of the alkylogens upon metallic oxides, especially silver
oxide : —

2C,H,I + Ag,0 = (C,H,),0 + 2AgI.

2. The action of the alkylogens upon the sodium alcoholates in
alcoholic solution. Mixed ethers are also formed here :

C H

C.Hj.ONa + C2H5CI = ' '\o + NaCI.

C H
C.Hj.ONa + CjHjCl = ' '\o + NaCl.

c,h/

Consult Berichte, 22, Ref. 381, upon the speed of these reactions.

3. Heating the sulphuric esters with alcohols : —

/O.C.H^ C,H

SO / + C,H,.OH = )o + SO^H,.

Ethyl Sulphuric Diethyl

Acid. Ether.

-O.CHg C2Hg.

S02<; + CjHs.OH = )0 + SO^Hj.

^OH CH3/

Methyl Sulphuric Methyl-ethyl

Acid. Ether.

The formation of ethers by directly heating the alcohols with
sulphuric acid is based on this reaction : —

zC.H^.OH + SO^H, = (C,H5),0 + SO^H^ + H^O.

By mixing and warming alcohol with sulphuric acid, a sulphuric
ester (together with water) is produced (p. 119). With excess of alco-
hol, on application of heat, this breaks up into ether and sulphuric
acid. The ether and water distil over while the sulphuric acid
remains behind. If a new portion of alcohol be added to this residue
the process repeats itself. In this way, an unlimited amount of

138 ORGANIC CHEMISTRY.

alcohol can be changed to ether by one and the same quantity or
sulphuric acid, providing the latter does not sustain a slight and
otherwise different transposition. Formerly, when the mechanism
of the reaction was yet unexplained, this process was included in
the category of catalytic actions. The explanation of the etheri-
fication process (by Williamson, in 1852) marks an important turn-
ing point in the history of chemistry.

When a mixture of two alcohols is permitted to act upon
sulphuric acid, three ethers are simultaneously formed ; two are
simple and one a mixed ether. Other polybasic acids, like phos-
phoric, arsenic, and boric, behave like sulphuric acid.

Ethers are neutral, volatile bodies, nearly insoluble in water.
The lowest members are liquid ; the highest, e. g. , cetyl ether, are
solids. Their boiling points are very much lower than those of the
corresponding alcohols {Annalen, 243, i).

Chemically; ethers are very indifferent, because all the hydrogen
is attached to carbon. When oxidized they yield the same pro-
ducts as their alcohols. They yield ethereal salts when heated with
concentrated sulphuric acid. Phosphorus chloride converts them
into alkyl chlorides : —

^CH3/° + ^^'= = ^''"^^^ + ^^=^^ + ^°^'''-

The same occurs when they are heated with the haloid acids,
especially with HI : —

^CH3/° + ^'^^ = C2H5I + CH,I -K H,0.

When acted upon by HI in the cold, they decompose into alcohol and an iodide.
With mixed ethers it is the iodide of the lower radical that is invariably produced
{^Berichte, g, 852) : —

:^h'/° + hi = CH3I -f- C,H,.OH.

5/

Many ethers, especially those with secondary and tertiary alkyls and those with
unsaturated alkyls, break up into alcohols {Berichte, 10, 1903), when heated with
water or dilute sulphuric acid to 150°.

Methyl Ether, (CH3)20, is prepared by heating methyl alcohol
with sulphuric acid. It is an agreeable-smelling gas, which may be
condensed to a liquid at about — 23°. Water dissolves 37 volumes
and sulphuric acid upwards of 600 volumes of the gas.

ETHERS.

'39

In preparing it 4 parts methyl alcohol and 6 parts concentrated sulphuric acid
are heated to 140°, in a ilask, in connection with a return condenser. The liber-
ated gas is purified by conducting it through potash. (Berichte, 7, 699.)

Substitution products form when chlorine is allowed to act
gradually: CHjCl.O.CHa boils at 60°, {C¥i.^CX)j:) boils at 105°,
and at last perchlormethyl ether, (CCl3)20, which decomposes
about 100°.

Ethyl Ether, (CjHs)^©, is prepared by heating ethyl alcohol
with sulphuric acid (p. 137).

A mixture of 5 parts (80-90 per cent.) alcohol and 9 parts HjSO^ is wanned
in a flask connected with a condenser. A thermometer passes through the cork
of the vessel and dips into the liquid. When the temperature has reached 140°,
a slow stream of alcohol is allowed to enter the flask through a tube leading into
the latter. The temperature given must be maintained. The ethyl sulphuric acid
produced at the beginning reacts at 140° upon the entering alcohol forming sul-
phuric acid and ether, which regularly distils over with the water formed in the
reaction. The distillate is a mixture of ether, water, and some alcohol. It is
shaken with soda, to combine sulphurous acid, the lighter layer of elher is siphoned
off and distilled over lime. There is always some alcohol in the product. To
remove this entirely distil repeatedly over sodium, until hydrogen is no longer
evolved. Any water in the ether may be detected by shaking the latter with an
equal volume of CSj, when a turbidity will ensue. To detect alcohol, ether is
agitated with aniline violet. When the former is absent the ether remains uncolored.

Ethyl ether is a mobile liquid with peculiar odor and specific
gravity at 0° of o. 736. When anhydrous, it does not congeal at
— 80°. It boils at 35° and evaporates very rapidly even at medium
temperatures. It dissolves in 10 parts water and is miscible with
alcohol. Nearly all the carbon compounds insoluble in water,
such as the fats and resins, are soluble in ether. It is extremely
inflammable, burning with a luminous flame. Its vapor forms a
highly explosive mixture with air. When inhaled, ether vapor
brings about unconsciousness. Hoffmann's Anodyne is a mixture of
3 parts alcohol and i part ether.

Ether unites with bromine to form peculiar, crystalline addition products, some-
what like bromine hydrate ; it combines, too, with water and metallic salts. When
heated with water and sulphuric acid to 1 80° ethyl alcohol results. Chlorine act-
ing upon cooled ether forms various substitution products : monochlorether, CH3.
CHCI.O.C2H5, boiling point 98°, dichlorethyl oxide, CH2CI.CHCI.O.C2H5,
boiling point 145°, and higher derivatives. An isomeric dichlorether, (CH3.CH.
CHoO, is produced when HCl acts upon aldehyde. It boils at 116°. Ferchlori-
nated Ether, {CJC\^)j:i, the last product of the action of chlorine on ethyl oxide,
is a crystalline body, fusing at 68° and decomposing upon distillation into CjClg
and trichloracetyl chloride, C2CI3O.CI.

When ozone is conducted into anhydrous ether, a thick liquid, having the com-
position CgH-oOj, is formed. This explodes on being heated. It is considered
an ethyl peroxide, {C^YL^^fi^. Water converU it into alcohol and hydrogen
peroxide.

14° ORGANIC CHEMISTRY.

Methyl Ethyl Ether, CHj.O.C.H., boils at ii°. Methyl Propyl Ether,
CH3.O.C3H,, at $0°.

Normal Propyl Ether, (CsH,)^^ boils at 86°. Isopropyl Ether, from
isopropyl iodide, boils at 60-62°.

Isoamyl Ether, (C5Hii)20, is formed together with amylene, and its poly-
merides when fermentation amyl alcohol is heated with sulphuric acid. It boils
at 176°, and has a specific gravity of 0.779.

Cetyl Ether, (CigH33)20, from cetyl iodide, crystallizes from ether in brilliant
leaflets, fuses at 55°, and boils at 300°.

Vinyl Ether, (C2H3)20, is obtained from vinyl sulphide by the action of dry
silver oxide. It boik at 39°.

Allyl Ether, (CsHsJjO, from allyl iodide, boils at 85°.

Vinyl Ethyl Ether, CjHj.O.C^Hj, is produced when chloracetal, CH^Cl.CH.
(O.C2Hg)2 (obtained from acetal by chlorination and from dichlor-ether, CH2CI.
CHCI.O.C2H5, by aid of sodium alcoholate), is heated with sodium. It is a
liquid with an allyl-like odor, and boils at 35.5°. The addition of chlorine changes
it again to dichlorether. When boiled with dilute sulphuric acid it decomposes into
ethyl alcohol and aldehyde (p. 134).

Allyl Ethyl Ether, C3H5.O.C2H5, from allyl iodide and sodium ethylate, boils
at 66°. It combines directly with Br,, Cl^ and ClOH.

MERCAPTANS AND THIO-ETHERS.

The sulphur analogues of the alcohols and ethers are the ikio-
alcohols or mercaptans and thioethers or alkyl-sulphides : — ,

CjHg.SH CjHjXc

Ethyl Hydrosulphide. CjHj/ '

Ethyl Sulphide.

Although they closely resemble the alcohols and ethers in general,
the sulphur in them imparts additional specific properties. . In
the alcohols the H of OH is replaceable by alkali metals almost
exclusively ; in the mercaptans it can also be replaced by heavy
metals (by action of metallic oxides). The mercaptans react very
readily with mercuric oxide, to form crystalline compounds : —

zCjHj.SH + HgO = (CjHj.SjjHg + H,0.

Hence their designation as mercaptans (from Mercurium capians).

The methods resorted to for their formation are perfectly analogous to those
employed for the alcohols. They are produced : —

(i) By the action of the alkylogens upon potassium sulphydrate in alcoholic
solution : —

C2H5CI + KSH = C2H5.SH + KCl.

Similarly, the thio-ethers are formed by action of the alkylogens upon potassium
sulphide : —

2C2H5CI + KjS = (C2H5)2S + 2KCI.

MERCAPTANS AND THIO-ETHERS. I4I

When polysuIpWdes are employed instead of KjS, polysulphides of the alcohol
radicals, like ^2J^5 \ g^, are obtained.
Etiiyl Bisulphide.

The alkyl sulphides are also produced when the alkylogens act upon the metal-
lic compounds of the mercaptans. Mixed thio-ethers can also- be made by this
method : — ^

C^H^.SK + C3H, Cl = ^2H5\g ^ KCl.

Farther, they are jiroduced when the mercury mercaptides are subjected to heat :—
(C,H,.S),Hg = (C,H,),S + HgS.

(?) By distilling salts of the sulphuric esters with potassium sulphydrate or
potassium sulphide (see p. 119) : r 1

SO^/^K^^B + KSH = C,H,.SH + SO.K,.
2SO /gj^^H, _|_ jj^g _ (C,H,),S + 2S0,K,.

The neutral esters of sulphuric acid, e.g., ^OJ^O.C^ViA^ (p. 148), also yield
mercaptans when heated with KSH. ^f t y. i

(3) A direct replacement of the O of alcohols and ethers by S may be attained
by phosphorus sulphide: —

SC^Hj.OH + P.Ss = 5C2H5.SH + P.Os and
S(C,H3),0 + P.S, = S(C3H,),S + P,0,.

The PjOj is likely to react further upon the alcohols, and then phosphoric acid
esters will appear simultaneously with the preceding compounds.

The alkyl disulphides (p. 140) are prepared jujt the same as the monosulphides ;
by distillation of salts of ethyl sulphuric acid with potassium disulphide ; also, by
the action of iodine upon the mercaptides : —

2C2H5.SK + I, = (C2H,),S, + 2KI.

A simpler method is the action of sulphuryl chloride upon the mercaptans
\Berichte, 18, 3178) : —

2C,H5.SH + S0,C1, = {C^n^^^^ + SO, + 2HCI.

Mixed alkyl disulphides result from the action of bromine upon a mixture of two
mercaptans (Berichte, 19, 3132).

Nascent hydrogen converts the alkyl disulphides into mercaptans, and zinc dust
reduces them to mercaptides : (€2115)282 + Zn = (C2H5.S)2Zn. On heating
■with potassium sulphide they yield potassium mercaptides {Berichte, 19, 3129).
See also phenyl disulphide.

142 ORGANIC CHEMISTRY.

The mercaptans and thio-ethers are colorless liquids, mostly in-
soluble in water, and possessed of a disagreeable, garlic-like odor.
The metallic derivatives of the mercaptans — termed mercaptides —
may, be obtained by the double decomposition of the alkali com-
pounds, and also by the direct action of the metallic oxides.

They absorb oxygen from the air and yield alkyl disulphides.
They become mercaptah and mercaptols by their union with alde-
hydes and ketones. When oxidized with nitric acid the mercaptans
unite with three atoms of oxygen, and yield the so-called sulphonic
acids (p. 152) : —

C2H,.SH + 30 = CjHs.SOjH.

Ethyl Sulphonic Acid.

Conversely, the mercaptans result by the reduction of the sulphonic
acids (their chlorides) (p. 152).

The sulphur ethers (the alkyl sulphides) also, take up one and
two oxygen atoms when treated with HNOs, and yield sulphoxides
and sulphones ; —

Diethyl Sulph-oxide. Diethyl-sulphone.

These compounds may be compared to the ketones. Nascent
hydrogen (Zn and HjSO^) deoxidizes the sulphoxides to sulphides.
The sulphones may be considered the esters of the alkyl sulphinic
acids, inasmuch as they can be formed from the salts of the latter
through the agency of the alkyl iodides (p. 154) : —

C2H,.S0,K -f- C,H,I = c^H°/S°2 + ^^-

Pot. Ethyl Sulphinate. Diethyl Sulphone.

Methyl Mercaptan, CHs.SIf, is alightliquid,t1iatwill swim on water,an(l boils
at 20°. Perchlor-methyl Mercaptan, CSCI4 = CCI3.SCI, results from the action
of chlorine upon SjC (Berichte, 20, 2377). It is a yellow liquid, boiling at 147°.
Nitric acid oxidizes it to CClj.SOjCl (p. 153). Stannous chloride converts it into
thiophosgene, CSClj. Methyl Sulphide, (CH3)jS, boils at 37.5°, and combines
with bromine to yield a crystalline compound, (CHj^jSBr^. Concentrated nitric
acid oxidizes methyl sulphide to sulphoxide, (CHjjjSO, which forms the salt
(CH3)2SO.N03H with an excess of acid. Barium carbonate separates the free
sulphoxide from this. Silver oxide produces the same compound when it acts
upon the bromide, (CH3)2SBrj. The sulphoxide is an oil, soluble in water and
congealed by cold. On heating methyl sulphide with fuming nitric acid we obtain
dimethyl-sulphone, (€113)2802. This is a crystalline body, fusing at 109° and boil-
ing at 238°. Methyl Disulphide, (€113)282, boils at 112° C.

Ethyl Mercaptan, C2H5.SH, is a colorless liquid, boiling at 36°,
and solidifying to a crystalline mass upon rapid evaporation. Its

MERCAPTANS AND THIO-ETHERS. 143

sp. gr. at 20° is 0.839. I' is but slightly soluble in water; readily
in alcohol and ether.

It may be prepared by saturating a concentrated KOH solution with hydrogen
sulphide, adding potassium ethyl' sulphate to this, and then distilling, when the light
mercaptan will swim upon the aqueous distillate. To obtain it perfectly pure, shake
with HgO, recrystallize the solid mercaptide from alcohol, and then decompose it
with HjS.

Mercury mercaptide, (C2H5.S)2Hg, crystallizes from alcohol in
brilliant leaflets, fusing at 86°, and is only slightly soluble in water.
When mercaptan is mixed with an alcoholic solution of HgClj
'the compound CjHj.S.HgCl is precipitated. The potassium and
sodium compounds are best obtained by dissolving the metals in
mercaptan diluted with ether ; they crystallize in white needles.

Ethyl Sulphide, (C2Hg)jS, obtained by the distillation of ethyl chloride with
an alcoholic solution of KjS, boils at 91°. It combines with some metallic chlo-
rides to yield double compounds, like (C2H5)2S.HgClj and [{C2H5)2S]j.PtCl^.

If oxidized with dilute nitric acid it forms the sulphoxide, (CjHjJjSO, an oily
liquid, which decomposes when distilled. Fuming nitric acid produces diethyl
sulphone, (CjHjjjSO^, soluble in water and alcohol, and crystallizing in large,
colorless plates. It melts at 70°, and boils, undecomposed, at 248°. Nascent
hydrogen (zinc and sulphuric acid) converts the sulphoxide into ethyl sulphide.

Ethyl Disulphide, (€2115)252, is obtained from ethyl mercaptan either by
means of iodine or sulphuryl chloride (p. 142). It is an oil with a garlicky odor.
It boils at 151°.

Propyl Mercaptan, CjHj.SH, boils at 68°, and the iso-derivative at 58-60°.
Dipropy I sulphide, {C^\l^)^5, boils at 130-135°.

Normal Butyl Mercaptan, C4HD.SH, boils at 98° ; dibutyl sulphide at 182° ;
di-isobutyl sulphide at 173°. The latter yields only one monoxide with nitric acid,
while a dioxide is also obtained from dibutyl sulphide [Annalen, 175, 349).

Cetyl Sulphide, (€,61133)28, crystallizes in shining leaflets, fusing at 57°.

Vinyl Sulphide, (C2H,)2S (compare p. 97), is the principal ingredient of the
oil of Allium ursinum, and is perfectly similar to allyl sulphide. It boils at 101° ;
its sp. gr. is 0.9125. It forms (C2H3Br2)2SBr2 with six atoms of bromine.
Silver oxide changes it to vinyl oxide (C2H3"')20 (p. 140). Like allyl sulphide, it
combines with silver nitrate and mercuric chloride to form perfectly analogous com-
pounds {Annalen, 241, 90).

Allyl Mercaptan, C3H5.SH, is very similar to ethyl mer-
captan, and boils at 90°.

Allyl Sulphide, (C3H5)2S, is the chief constituent of the oil of
garlic (from Allium sativuni), and is obtained by the distillation of
garlic with water. It occurs in many of the Cruciferce. It may be
prepared artificially by digesting allyl iodide with potassium sul-
phide in alcoholic solution. It is a colorless, disagreeable-smelling
oil, but slightly soluble in water. It boils at 140°. It forms crys-
talline precipitates with alcoholic solutions of HgCU and PtCU.

144 ORGANIC CHEMISTRY.

With silver nitrate it yields the crystalline compound (C3H5)2S.
2AgN03.

AUyl mustard oil is produced on heating the mercury derivative
with potassium sulphocyanide. Vinyl mustard oil is prepared in an
analogous manner.

Sulphine Compounds. The sulphides of the alcohol radicals
(thio-ethers) combine with the iodides (also with bromides and
chlorides) of the alcohol radicals at ordinary temperatures, more
rapidly on application of heat, and form crystalline compounds : —

(C,H5),S + C,H,I = {C^U,\Sl.

TriethVl Sttlphine Iodide.

These are perfectly analogous to the halogen derivatives of the
strong basic radicals (the alkali metals). By the action of moist
silver oxide the halogen atom in them may be replaced by hydroxyl,
and hydroxides similar to potassium hydroxide be formed : —

(C,ll,),Sl + AgOH = (C,H5)3S.OH + Agl.

Tbe sulphine haloids are also obtained on heating the sulphur ethers with the
halogen hydrides : —

2(C,H,),S + HI = (C,H,),SI + C,H,.SH.

The acid chlorides react similarly. Often wheii the alkyl iodides act on the
suljhides of higher alkyls the latter are displaced (^Berichte, 8, 325) : —

(C,H,),S + 3CH3I = (CH3)3SI + 2C,H,I.

(C2H5)2S.CH3l and p „' ")S.C2H5l are to be isomeric, in which case a

difference of the 4 valences of S would be proven.

As in similar cases, the most recent investigations^ have shown them to be identi-
cal (Berichte, 22, Ref.

The sulphine hydroxides are crystalline, efflorescent, strongly
basic bodies, readily soluble in water. Like the alkalies they pre-
cipitate metallic hydroxides from metallic salts, set ammonia free
from ammoniacal salts, absorb CO2 and saturate acids, with the
formation of neutral salts : —

(C2H,),S.OH + NO3H = (C2H5)3S.N03 + H,0.

We thus observe that relations similar to those noted with the
nitrogen group prevail with sulphur (also with selenium and tellu-
rium). Nitrogen and phosphorus combine with four hydrogen
atoms (also with alcoholic radicals) to form the groups ammonium,
NH4, and phosphonium, PH4, which yield compounds similar to

SELENIUM AND TELLURIUM COMPOUNDS. 1 45

those of the alkali metals. Sulphur and its analogues combine in
like manner with three monovalent alkyls, and give sulphonium and
sulphine derivatives. Other metalloids and the less positive metals,
like lead and tin, exhibit a perfectly similar behavior. By addition
of hydrogen or alkyls they acquire a strongly basic, metallic char-
acter (see the metallo-organic compounds).

Only the sulphine derivatives of methane and ethane have been carefully
studied ; the former are perfectly similar to the latter.

Triethyl Sulphine Iodide, (€2115)331, obtained by heating ethyl sulphide
and iodide to 100°, crystallizes from water and alcohol in rhombic plates. Pla-
tinum chloride precipitates the double salt [(C2H5)3SCl]2.PtCl4, from a solution
of the chloride. It forms red needles.

Triethyl Sulphine Hydroxide, (C2Hj)3S.OH, forms efflorescent crystals and
possesses an alkaline reaction. Its nitrate, (C2Hg)3S.O.N02, crystallizes in
efflorescent scales. Hydrochloric acid converts the hydroxide into chloride,
(C2H5),SC1.

SELENIUM AND TELLURIUM COMPOUNDS.

These are perfectly analogous to the sulphur compounds. The methods of
formation are also similar.

Ethyl Hydroselenide, C2H5.SeH, is a colorless, unpleasant-smelling, very
mobile liquid. It combines readily with mercuric oxide to form a mercaptide.

Ethyl Selenide, (C2H5)2Se, is a heavy, yellow oil, boiling at 108°. It unites
directly with the halogens, e. g., (C2H5)2SeCl2. It dissolves in nitric acid with
formation of the oxide, (C2H5)2SeO, which yields the salt, (C2H5)2Se(N03)2.

Methyl Telluride, (CH3)2Te, is obtained by distilling barium methyl sul-
phate with potassium telluride. It is a heavy, yellow oil, boiling from 80-82°.
Dilute nitric acid' converts it into the nitrate of the oxide, (CH3)2Te(N03)2.
From an aqueous solution of this salt hydrochloric acid precipitates a white,
crystaUine chloride, (CH3)2TeCl2; this yields the oxide, (CH3)jTeO, with
silver oxide. This is a crystalline, efflorescent compound. In properties it
resembles CaO and PbO. It reacts strongly alkaline, expels ammonia from am-
monium salts, and forms salts by neutralizing acids.

Methyl telluride combines with methyl iodide to form Trimethyl tellurium
iodide, (CH3)3TeI, which passes into the strongly basic ^ hydroxide,
(CH3)3Te.OH, by the action of moist silver oxide. It resembles potassium

hydroxide. . , , ,

Tri-ethyl Tellurium Chloride, Te(C2H5)3Cl, has been obtamed by the
action of zinc ethide on tellurium tetrachloride. It consists of colorless leaflets,
melting at 174° C. Hydriodic acid converts it into the iodide, melting at 9°

{Berichte, 21, 2043). , ,. , , ^ ., , v, • •. • -j

Ethyl Telluride, (C2H5)2Te, is a reddish-colored oil, soluble m nitric acid
with formation of {C2H5)2Te(N03)2. Hydrochloric acid precipitates the
chloride, (CjHJjTeClj, from an aqueous solution of the salt. Hydriodic acid
precipitates the iodide, (C2H5)2Tel2. This is an orange-red powder, fusing at
50°.

146 OKGANIC CHEMISTRY.

ESTERS OF THE MINERAL ACIDS.

If we compare the alcohols with the metallic bases, the esters or
compound ethers (see p. 137) are perfectly analogous in constitution
to the salts. We can regard them as alcohol derivatives, arising
by the substitution of acid radicals for alcoholic hydrogen, or they
may be viewed as derivatives of the acids formed by substituting
alcohol radicals for the hydrogen of acids. The various designa-
tions of esters would indicate this : —

CJH5.O.NO2 or NO2.O.C2H5.
Ethyl Nitrate. Nitric Ethyl Ester.

The first view is better adapted for esters of the polyhydric
alcohols, while the second answers best for those of the polybasic
acids. In these all or only one hydrogen atom can be replaced by
alcohol radicals ; thus arise the neutral esters and the so-called ether-
acids, which correspond to the acid salts : —

550 /O-CjHj eo /O.C2H5

Sulphuric Ethyl Ester. Ethyl Sulphuric Acid.

Almost all the neutral esters are volatile; therefore the determi-
nation of their vapor density is a convenient means of establishing
the molecular size and also the basicity of the acids. The ether-acids
are not volatile, but soluble in water and yield salts with the bases.

All esters, and especially the ether-acids are decomposed into
alcohols and acids when heated with water. Sodium and potassium
hydroxides, in aqueous or alkaline solution, accomplish this with
great readiness when aided by heat. The process is termed saponifi-
cation : —

C^h'^O /O + ^O^ = C2H5.OH -I- C,H,O.OK.

>-2i.ij>-'/ Alcohol. Potassium Acetate.

Ethyl Acetate, Ethyl Acetic Ester.

There are two synthetic methods of producing the esters that
favor the views of considering them derivatives of alcohols or acids.
These are : —

(i) By reacting on the acids (their silver or alkali salts) with
alkylogens : —

NO,.O.Ag -f- C.HJ = NOj.O.C.H^ -f Agl.

(2) By acting upon the alcohols or metallic alcoholates with acid
chlorides : —

zC.Hj.OH -f- SO.Cl, = SO,/°-^2J^5 + 2HCI.

SC.Hj.OH -f BCI3 = B(0.C,h/)3 ' + 3HCI.

In addition to these reactions, which generally occur with ease.

NITRIC ACID ETHERS. 1 47

the esters can also be prepared by allowing alcohols and acids to act
directly ; water is also produced : —

C2H5.OH + NO2.OH = C2H5.O.NO2 + H2O.

This transposition, however, only takes place gradually, progressing with time ;
it is accelerated by heat, but is never complete. We always find alcohols and
acids together with the esteri, and they do not react any further upon each other.
If the ester be removed, c g., by distillation, from the mixture, as it is formed, an
almost perfect reaction may be attained. These relations are perfectly similar to
those observed in the action of two salts (compare Inorganic Chemistry). A
more comprehensive statement of the processes taking place in the action of acids
and alcohols will be given under the esters of the fatty acids.

When acted upon by alcohols, the polybasic acids mostly yield
the primary esters or ether-acids. The haloid acids behave just like
the mono-basic acids ; the alkylogens formed (see p. 93) may be
termed haloid esters of the alcohols.

NITRIC ACID ETHERS (ESTERS).

Methyl Nitrate, CH3.O.NO2, Miric Methyl Ester, is produced
by distilling methyl alcohol with nitric acid. It is a colorless
liquid, slightly soluble in water, and boiling at 66°. Its specific
gravity, at 20°, is 1.182. When struck or heated to 150° it ex-
plodes very violently.

It is prepared by distilling a mixture of methyl alcohol (5 pts.) with sulphuric
acid (10 pts.) and nitre (2 pts.), or a mixture of wood spirit and nitric acid",
adding a little urea at the same time (compare ethyl nitrate).

Ethyl Nitrate, C2H5.O.NO2, Mtric Ethyl Ester. When
alcohol is heated with nitric acid, there is a partial oxidation of
the alcohol, which causes the formation of nitrous acid and nitrous
ethyl ester. If, however, we destroy the nitrous acid (best by
addition of urea), pure nitric ethyl ester results.

Distil 120-150 grms. of a mixture consisting of i volume nitric acid (of specific
gravity 1.4) and 2 volumes alcohol (80-90 per cent.), to which 1-2 grams urea
have been added. Explosions sometimes occur when larger quantities are employed.
The distillate is shaken with water, and the heavier ester separated from the aqueous
liquid.

Ethyl nitrate is a colorless, pleasant-smelling liquid, boiling at
86°, and having a specific gravity of 1.112, at 15°. It is almost
insoluble in water, and burns with a white light. It will explode
if suddenly exposed to high heat. Heated with ammonia it passes
into ethylamine nitrate. Tin and hydrochloric acid convert it into
hydroxylamine.

Ths propyl ester, C^H^O.^O^, {Benchte, 14, 421) boils at 110°, the iso-propyl
ester at 101-102°, and the isobutyl ester at 123°. Cetyl ester, C15H33.O.NO2,
solidifies at 10°.

148 ORGANIC CHEMISTRY.

NITROUS ACID ETHERS (ESTERS).

These are isomeric with the nitro-paraffins (p. 107). The group
NO2 is present in both ; while, however, in the nitro-compounds
nitrogen is combined with carbon, in the esters the union is effected
by oxygen : —

CjHj.NO, CjHg^O.NO.

Nitro-ethane. Nitrous Ethyl Ester. _

The nitrous esters, as might be inferred from their different
structure, decompose into alcohols and nitrous acid when acted on
by alkalies. Similar treatment will nof decompose the nitro-com-
pounds. Nascent hydrogen (tin atid hydrochloric acid) converts
the latter into amines, while the esters yield alcohols.

Nitrous acid esters are produced in the action of nitrous acid
upon the alcohols. The latter are saturated with nitrous acid vapors
and distilled ; or a mixture of alcohol, KNO3 and HjSOi is distilled.
A late procedure consists in adding the calculated quantity of alco-
hol to the dilute solution of sodium nitrite. To this cold mixture
add hydrochloric acid, then distil {Berichte, 19, 915).

Methyl Nitrite, Nitrous Methyl Ester, CH5.O.NO, is an agreeable-smelling gas.
When exposed to great cold, it is condensed to a yellowish liquid, boiling at — 12°.

Ethyl Nitrite, Nitrous Ethyl Ester, CjHj.O.NO, is a mobile, yellowish liquid,
of specific gravity 0.947, at 15°, and boils at+ 16°. It is insoluble in water, and
possesses an odor resembling that of apples. It is best obtained by heating a mix-
ture of alcohol and nitric acid with copper turnings, or may be made by distilling a
mixture of alcohol and fuming nitric. acid, after having stood for some hpurs. The
distillate is shaken with water (to withdraw alcohol) and a soda solution, then de-
hydrated and distilled (see Annalen, 126, 71 ; Berichte, 21, Ref. 515).

When ethyl nitrite stands with water it gradually decomposes, nitrogen oxide
being eliminated; an explosion may occur under some conditions. Hydrogen
sulphide changes it ijito alcohol and ammonia.

Tertiary Butyl Nitrite, C(CH3)3.0.NO, boils at 77°.

Amyl Nitrite, CjHjj.O.NO, obtained by the distillation of fermentation amyl
alcohol with nitric acid, is a yellow liquid, boiling at 96°; its sp. gr. is 0.902. An
explosion takes place when the vapors are heated to 250°. Nascent hydrogen
changes it into amyl alcohol and ammonia. Heated with methyl alcohol, it is
transformed into methyl nitrite and amyl alcohol. The result is the same if ethyl
alcohol be used (Berichte, 20, 656).

ESTERS OF SULPHURIC ACID (ETHYL SULPHATES).

Sulphuric acid being dibasic forms two series of esters^the neu-
tral esters and the primary esters or ether-acids (ethereal salts)
(p. 146.)

(i) The neutral esters are formed by the action of the alkyl
iodides upon silver sulphate, SOjAgj ; they are also produced, in

ESTERS OF SULPHURIC ACID. 149

slight quantity on heating the primary esters or alcohols with sul-
phuric acid. They can be extracted with chloroform from the
product, and are heavy liquids, soluble in ether, possess an odor
like that of peppermint, and boil without decomposition. They
will sink in water, and gradually decompose into a primary ester
and alcohol : —

The Dimethyl Ester, SO^{O.CB^^ — normal methyl sulphate— boils, without
decomposition, at 188°. The diethyl-ester, 802(0.02115)2, normal ethyl sulphate,
boils at 208°, sustaining at the same time a partial decomposition. When heated
with alcohol, ethyl sulphuric acid and ethyl ether are formed {Berichte, 13, 1699;
15. 947)-

(2) The primary esters or ether-acids are produced when the
alcohols are mixed with concentrated sulphuric acid : —

S02(OH)2 + C2H,.OH = S02<^°-^^^= + H2O.

The reaction takes place only when aided by heat, and it is not complete, be-
cause the mixture always contains free sulphuric acid and alcohol (compare p.
147). To isolate the ether-acids, the product of the reaction is diluted with water
and boiled up with an excess of barium carbonate. In this way the unaffected sul-
phuric acid is thrown out as barium sulphate ; the barium salts of the ether-acids
are soluble and crystallize out when the solution is evaporated. To obtain the
acids in a free state their salts are treated with sulphuric acid or the lead salts
(obtained by saturating the acids with lead carbonate) may be decomposed by
hydrogen sulphide, and the solution allowed to evaporate over sulphuric acid.

These acids are also prepared by the union of the alkylens with
concentrated sulphuric acid (p. 80). They are thick liquids, that
cannot be distilled. They sometimes crystallize. In water and
alcohol they dissolve readily, but are insoluble, in ether. When
boiled or warmed with water they break up into sulphuric acid
and alcohol : —

S°»\Oh'"' + ^^^ = S°*^^ + C:=H5-°^-

When distilled they yield sulphuric acid and alkylens (p. 80.)
Upon heating them with alcohols simple and mixed ethers (p. 136)
are produced.

They show a strongly acid reaction and furnish salts that dissolve
quite readily in water, and crystallize without great trouble. The
salts gradually change' to sulphates and alcohol when they are
boiled with water. Those with the alkahes are frequently applied
in different reactions. Thus with KSH and K^S they yield mer-

15° ORGANIC CHEMISTRY.

captans and thio-ethers (p. 140) ; with salts of fatty acids they
furnish esters, and with KCN the alkyl cyanides,, etc.

Methyl Sulphuric Acid, S04(CH3)H, is a thick oil, that does not solidify at
—30°. The potassium salt (S04)CH3K+ ^H^O), forms deliquescent leaflets.
T-heb'aiium salt, (CH3.S04)2Ba + zH^O, crystallizes in plates.

Ethyl Sulphuric Acid, S04(C2H5)H, is obtained by mixing I part alcohol with
2 parts concentrated sulphuric acid, and by the union of CjH^ with sulphuric acid
(p. 81). It is a thick, non-crystallizable liquid, having, at 16°, a specific gravity
of 1.316. The potassium salt, S04(C2H5)K, is anhydrous; it crystallizes in
plates, that dissolve quite readily. The .barium and calcium,,$alts crystallize in
large tablets with two molecules of H^O each. Consult Annalen, 218, 299,,for
two different barium salts bf methyl and ethyl sulphuric acid. "

Amyl Sulphuric Acid, ?>0^{C^iiii)^. ^Two isomeric barium amyl sulphates
are obtained by mixing ordinary fermentation amyl alcohol with sulphuric acid,
and then neutralizing with barium carbonate. These salts both crystallize in
large tablets, and show varying solubility in water, and may be separated by
repeated crystallization. The more sparingly soluble salt is produced in the
greater abundance and furnishes isobutyl carbinol, while active amyl alcohol is
obtained from the more readily soluble salt (p. 131).

Allyl Sulphuric Acid, 804(03115)11, has been made from allyl alcohol and
sulphuric acid.

The chlorides or chloranhydrides oi ihe ether sulphuric acids/ SOjC^pj ^ ^ I,

called esters of chlorsulphonic acids, result in the action of sulphuryl chloride
upon the alcohols : —

C.H^.OH + SO.Cl, = SO./gj^^Ha ^ hCI;

Chloride of Ethyl
Sulphuric Acid.

and by the action of SO, upon the esters of hypochlotous acids (Berichte, 19,
860) :—

SO, + CIO.C.H^ = ^^(^c^-H^.

All are liquids with penetrating odor, and boil with scarcely any decomposition.
Cold water decomposes them very slowly, without the formation of the ether
acids. These they yield, together with ethyl chlorides, on adding alcohol to them.
The reaction is rather energetic.

Chloride of Ethyl Sulphuric Acid, CjHg.O.SOjCl, boils about 152°.
Methyl Sulphuric Chloride, CHj.O.SOjCl, boils at 132°.

SULPHUROUS ACID ETHERS (ESTERS).

The empirical formula of sulphurous acid, SO3H2, may have one
of two possible structures : —

JX./OH VI

^"\0H ""^ HSO^.OH.

Symm. Sulphurous Acid. Unsymm. Sulphurous Acid.

The ordinary sulphites correspond to formula 2, and it appears

SULPHUROUS ACID ETHERS. 151

that in them one atom of metal is in direct combination with
sulphur : —

Ag.SO2.OAg. K.SO2.OH.

Silver Sulphite. Prim. Pot. Sulphite.

This is evident from the following considerations : —

(i) JEsters of Symmetrical Sulphurous Acid.

These are produced in the aclion of thionyl chloride, SOClj, or sulphur mono-
chloride, SjClj, upon alcohols : —

SOjClj + 2C2H5.OH = SO^'q^^Hs ^ 2HCI and
S^CU + 3C2H5.OH =S0/°;^^g^ + C^H^.SH + 2HCI.

The mercaptan that is simultaneously formed sustains further decomposition,
The sulphites thus produced are volatile liquids, insoluble in water, with an odor
resembling that of peppermint, and decomposed by water, especially when heated,
into alcohols and sulphurous acid.

Sulphurous Methyl Ester, SO{O.CH3)2, methyl sulphite, boils at 121°.

The Ethyl-Ester, SO(O.C2H5)2, boils at 161°. Its specific gravity at 0° is

1.106. PCI3 converts it into the chloride, SO<Qq^ jj , a liquid boiling at

122°, and decomposed by H^O into alcohol, SO, and HCl. It is isomeric with
ethyl sulphonic chloride, CjHs.SOjCl (p. 153). On mixing the ester with a

dilute solution of the equivalent amount of KOH, a potassium salt, SO.^q'jt* *'

separates in glistening scales. This is viewed as a salt of the unstable ethyl sul-
phurous acid.

(2) Esters of the Unsymmetrical Sulphurous Acid. — These are
formed by the action of silver sulphite upon the alkyl iodides in
ethereal solution : —

Ag.SOj.OAg + 2C2H5I = C2H5.SO2.O.C2H5 + 2AgI.

One of the alkyl groups is joined to sulphur, the other to oxygen.
When heated with water the latter one only is separated as alcohol,
and sulphonic acids result : —

C,H5.SO,.O.C,H, -f H,0 = C,H,.SO,,OH + C^H.-OH.

Ethyl Sulphonic Acid.

Conversely, the esters can be prepared from the sulphonic acids,
by acting on their salts with alkyl iodides or upon the sodium alco-
holates with the chlorides of the sulphonic acids :—

C2H5.SO2CI + C^Hs.ONa = C2H5.SO,.p.C2H5 H- NaCl.
Ethyl Sulphonic Chloride. Ethyl Sulphonic Eth^Ester.

Hence, the esters formed from silver sulphite may be regarded
as esters of the sulpho-acids. They boil much higher than the
isomeric esters of symmetrical sulphurous acid. They are distm-

152 ORGANIC CHEMISTRY.

guished from the latter by having but one of their alkyl groups
separated out by alkalies (see above).

Ethyl Sulphonic Ethyl Ester, CjHj.SO^.O.CjHj, produced as above
described, boils at 213.4°, and has a sp. gr. of 1.171 at 0°.
The methyl ester, CjHs.SO^.O.CHs, boils at 198°.

3. Sulpho-acids, C„H2„ + iS02.0H.

The sulpho- or sulphonic acids, which contain the group — SO2OH
attached to carbon, may be viewed as esters of unsymmetrical sul-
phurous acid, HSO2OH, inasmuch as they are produced from its
neutral esters by the separation of an alkyl group (p. 151). Fur-
thermore, their salts are directly obtained from the alkaline sulphites
(preferably ammonium sulphite) by heating them with alkylogens
(in concentrated aqueous solution to 120-150°) : —

K.SO2.OK -f CjHjI = C,H5.SO,.OK + KI.

Potassium Ethyl Sulphonate,

2K.SOj.OK -f- CjHjBrj = QHj^l^^-^^-f- 2KBr-
Potassium Ethylene Disulphonate.

The oxidation of mercaptans and alkyl disulphides (p. 142)
(also sulphocyanides) with nitric acid also affords the sulpho-
acids : —

CjHj.SH + 30 = C,H5.SOj.OH.

Ethyl Mercaptan. Ethyl Sulphonic Acid.

Conversely, these sulpho-acids can be again reduced to mercaptans
(by action of zinc and hydrochloric acid upon their chlorides — as
QH5.SO2CI): QH5 SOyCl + 3H2 = QH5.SH + HCl + 2HjO.
They may also be obtained by oxidizing the sulphinic acids and
can be again converted into the latter- (see p. 154). All these
reactions plainly indicate that in the sulpho-acids the alkyl group
is joined to sulphur, and that, therefore, it is very probable that in
the sulphites the one atom of metal is directly combined with sul-
phur. Finally, the sulpho-acids can be prepared by the action of
sulphuric acid or sulphur trioxide (SO3) upon alcohols, ethers and
various other bodies. This reaction is very general and'easily exe-
cuted with the benzene derivatives.

These acids are thick liquids, readily soluble in water, and gen-
erally crystallizable. They suffer decomposition when exposed to
heat, but are not altered when boiled with alkaline hydroxides. When
fused with solid alkalies they break up vcAo sulphites sxi^ alcohols: —

C2H5.SOj,.OK + KOH = KSOj.OK + qHj.OH.

PCI5 changes them to chlorides, e.g., CjH^.SOjCl, which become mercaptans
through the agency of hydrogen, or by the action of sodium alcoholates pass into
the neutral esters — CjH5.SO3.CjH5 (p. 151).

ESTERS OF THIO-SULPHURIC ACID. 153

Methyl Sulphonic Acid, CH3.SO3H, is a thick, uncrystalliz-
able liquid, soluble in water. When heated above 130° it sustains
decomposition. In order to obtain the pure acid it is converted
into the lead salt, the solution of which is treated with H^S, the lead
sulphide filtered off and the filtrate concentrated.

Its salts are readily soluble in water and crystallize well. The barium salt,
(CH3.S0s)jBa + i^HjO, crystallizes in rhombic plates. Methyl sulphonic
chloride, CHj.SOjCl, boils near 1 60° and is slowly decomposed by water into the
acid and hydrogen chloride.

The following is an interesting method of preparing methyl sulphonic acid :
Moist chlorine is allowed to act upon carbon disulphide, CSj, when there is pro-
duced the compound, CC1^.S02, which must be considered as the chloride of tri-
chlormethyl sulphonic acid, CClj.SO^Cl. It is colorless and crystalline ; it fuses
^^ 135°) ^"d boils at 170°. It is soluble in alcohol and ether, but not in water.
Its odor resembles that of camphor, and excites tears. To prepare the chloride a
mixture of 500 gr. HCl, 300 grms. coarse-grained CrjOjKj, 200 gr. nitric acid
and 30 gr. CSj, are allowed to stand in an open flask. Water is then added, to
dissolve the salts, and the crystals of CCl^.SOj are filtered off.

On boiling the chloride with potassium or barium hydrate salts of trichlormethyl
sulphonic acid, CClj.SOjH, are formed. The barium salt, (CCl3.S08)2Ba + HjO,
crystallizes in leaflets. Sulphuric acid releases the acid from it. It consists
of deliquescent prisms. Nascent hydrogen (sodium amalgam) in an aqueous solu-
tion of the acid produces successively CHCl^.SOjH, CH^Cl.SOjH, and, finally,
CHj.SOjH — methyl sulphonic acid. These reactions represent one of the first
instances of the conversion of an inorganic (mineral) substance (CSj) into a so-
called organic derivative.

Ethyl Sulphonic Acid, CjHj.SOsH, is a thick, crystallizable
liquid.

Its lead salt, (CjH5.S03)jPb, crystallizes in readily soluble leaflets. Concen-
trated nitric acid oxidizes it to ethyl sulphuric acid, S04(C2H5)H. Its chloride,
CjH5.SOjCl, is a Uquid, boiling at 173°. Its ethyl ester, C2H5.SO3.C2H5, boils at
213.4° (p. 151).

ESTERS OF THIO-SULPHURIC ACID (AND ALKYL THIO-
SULPHONIC ACIDS).

On p. 151 we saw how the alkyl sulphonic acids were obtained firom the sul-
phites by the alkyl iodides. In the same way the corresponding alkyl thiosul-
phonic acids can be prepared from the salts of thiosulphuric acid (hyposulphurous
acid) : —

KS.S08K + C^HjI = CjHj.S.SOaK + KI.

Only the primary saturated alkyl iodides, however, react in this way {Berichte,
15, 1939). The ethyl compound can be made, too, by letting iodine act on a
mixture of mercaptan and sodium sulphite, Na^SOj. , , , , , . .,

The salts of these acids crystallize well. When boiled with hydrochloric acid
they are decomposed into mercaptans and primary sulphates. When heated they
break up into alkyl disulphides, (CjHJ^Sj, and dithionates (SO^Kj -j- SOj).

13

ISA ORGANIC CHEMISTRY.

The Alkyl Thiosulphonic Acids, R.SOj.SH, differ from the alkyl thiosul-
phuric acids. They are formed by the action of the chlorides of sulpho-acids upon
potassium sulphide: C2H5.SO2CI + KjS = KCl + CjHj.SOa.SK. Theesters,
R.SOjSK, of this new class were formerly called alkyl disulphoxides, R^S^O^, and
are obtained from the alkali salts by the action of the alkyl bromides {Bericiie,
15, 123),C2H5.S02.SK + CjHsBr = C2H5.SO2.SK + KBr; and bythe ox-
idation of mercaptans and alkyl dlsulphides with dildte nitric acid : (C2H5)2Sj +
O2 = C^Hg.SOj.SCjHj. These esters are liquids, insoluble in water, and pos-
sessed of a disgusting onion-like odor. When distilled they suffer partial decom-
position, but in a current of steam volatilize undecomposed. They are saponified
by the alkalies, forming sulphinic acids and disulphides, while the latter, in part,
decompose into sulphinic acids and mercaptans (Berichie, ig, 1241). With potas-
sium sulphide the esters yield alkyl thiosulphonates and mercaptides {Berichte, 19,
3131). Zinc and sulphuric acid reduce the esters to disulphides and mercaptans,
while zinc dust changes them to alkyl sulphinic acids (zinc salts) and zinc mercap-
tides. Nitric acid oxidizes th^' esters to two molecules of the sulphinic acids.
Ethyl Thiosulphuric Ethyl Ester, CjHj.SOj.S.CjHj, boils from I30°-I40°-

Esters of Hydrosulphurous Acid — Sulphinic Acids. Two structural

formulas are possible fpr hydrosulphurous acid : H.SO.OH and ji "^SO,. Re-

• r

place one hydrogen atom and the sulphinic acids result, «.^.: (l) C2H5.SO.OH or

(2) tV' ^ pSOj. Both forms are probably identical or tautomeric (p. 54), where-
as their alkyl derivatives are isomeric : —

CjH^.SO.O.CaHj and c^hO^^s-

Ethyl Sulphinic Diethyl-sulphone.

Ester.

These relations are exactly analogous to those of the'isomeric esters of sulphurous
acid (p. 151).

When SOj acts upon the zinc alkyls, the sulphinic acids (their zinc salts)
result : —

(CjHg)2Zn -f 2SO2 == (C2H5.SOj)j2ii, just as the carbonic acids {e.g.,
CjHj.COjH) are produced by the action of CO,.

A simpler method would be to let zinc dust act upon the chlorides of the snl-
phonic acids: 2C2H5.SO2CI + 2Zn = (C2H5.S02)2Zn + ZnCl,. To obtain
the free acids the zinc salts are converted into barium salts and these, in turn, de-
composed by sulphuric acid. The sulphinic acids are thick, strongly acid liquids,
decomposed by heat. Their sodium salts are formed in the oxidation of the oxy-
sodium mercaptides in the air: C2H5.SNa -f- 0, = C2H5.S02Na.

The sulphones (p. 142) are produced in the action of alkyl iodides upon the
alkaline sulphonates, while the real esters result from the etheriBcation of the acids
with alcohol and hydrochloric acid, or by the action of chlorcarbonic esters upon
the sulphinates {Berichte, 18, 2493) : R.SOjNa -f Cl.COjR = R.SO.OR +
CO3 + NaCl. When these esters are saponified by alcohol or water they break
up into alcohol and sulphinic acid, while the isomeric sulphines are not altered.
Free sulphinic acids are not very stable ; they rapidly oxidize to sulphonic acids.
Potassium permanganate and acetic acid convert the sulphinic esters into sulphonic
esters (Berichte, 19, 1225), whereas the isomeric sulphones remain unchanged.
Methyl Sulphinic Acid, GHj.SOjH, and Ethyl Sulphinic Acid, CjHg.SOjH,
are liquids, dissolving readily in water. In aqueous solution they soon decompose
with the separation of sulphur.

ESTERS OF THE PHOSPHORIC ACIDS. 155

ESTERS OF CHLORIC ACIDS.

Ethyl Perchlorate, ClOj.O.CjHj, is obtained by the action of ethyl iodide
upon silver perchlorate. It is a colorless liquid that explodes when heated.

The Esters of hypochlorous acid, ClOH, form on mixing concentrated aqueous
■Solutions of hypochlorous acid with alcohol. They separate as yellow oils. When
carefully heated they boil without decomposition, but if overheated they explode
with great violence (Berichte, i8, 1767, and 19, 857).

Methyl Hypochlorite, CIOCH3, boils at 12°; Ethyl Hypochlorite, ClOCjHj,
boils at 36°. Both have a penetrating odor that attacks the respiratory organs
powerfully.

Sulphur dioxide converts these esters into chlorsulphonic esters (p. ijo), while
with KCN they yield chlorimide carbonic acid esters, C(NCl) (0.02115)2 (see
these).

ESTERS OF BORIC ACID.

The esters of the tribasic acid, B(0H)3, are formed along with those of the
monobasic acid, BO.OH, when BCI3 acts upon the alcohols. The first are vola-
tile; thick liquids, while the second decompose when distilled. Acid esters are not
known. Water decomposes both the preceding varieties.

Methyl Borate, B(O.CH3)3, boils at 65°.

Ethyl Borate, B(O.C2H5)3, is obtained by distilling potassium ethyl sulphate
together with borax. It boils at 119°.

ESTERS OF THE PHOSPHORIC ACIDS.

Tribasic phosphoric acid, P0(0H)3, yields three series of esters — the primary,
secondary and tertiary, all of which are thick liquids. Only the last volatilize
without decomposition.

Triethyl Phosphoric Ester, PO.(O.C2H5)3, is formed when phosphorus oxy-
cbloride acts upon sodium ethylate : —

POCI5 + sCjHj.ONa = PO(O.C2H5)3 + sNaCI.

A thick liquid, soluble in water, alcohol and ether, and boiling at 215°. The
aqueous solution decomposes readily into diethyl-phosphoric acid, the lead salt of
which is made by boiling with PbO.

Diethyl Phosphoric Acid, VoV^^^^^'^' is obtained by decomposing

the lead salt with H2S. It is a thick syrup. The lead salt crystallizes in silky

needles. When heated it passes into the triethyl ester and lead monoethyl

phosphate, insoluble in water. The acid of this last salt has the formula
PO(OH)a.O.C2H5.

The esters of symmetrical phosphorous acid, P(0H)3, result when PCI3 acts on
the alcohols. Triethyl phosphite, P(0.C2H5)3, boils at 191°. , ,. . ,

Acids of the structure C2H5.PO(OH)2, corresponding to the sulpho-acids,
C H SO .OH, (p. 152) may be derived from the unsymmetrical phosphorous
acid, HPd(OH)2. They are produced by the oxidation of primary phosphines
(see these) with nitric acid: —

P(CH3)H2 +03 = CH3.PO(OH)2.

IS6 ORGANIC CHEMISTRY.

They are spermaceti-like, crystalline bodies, soluble in water and reacting
strongly acid. They furnish both acid and neutral salts, that are mostly crystal-
lizable.

Methyl Phosphite, CH3PO(OH)2, melts at 105°. PCI5 converts it into
CH3.POCI2, which fuses at 32°, and boils at 163°. Water again produces the
acid from the chloride.

Ethyl Phosphite, C^H^.TOiOU)^, melts at 44°.

PCI3 converts aldehydes into compounds, which yield oxy-alkyl phosphorous
acids, ^. g-., CH3.CH.OH.PO(OH)a (Berichte, ;8, Ref. in), when treated with
water.

From hypophosphorous acid, Hj.PO.OH, we obtain similar compounds that can
be called phosphinic acids. They result yirhen nitric acid acts on the secondary
phosphines : —

P(CH3),H + O, = (CH3),P0.OH,

Dimethyl Phosphinic Acid, (CH3)2PO.OH, resepibles ppraffin, fuses at 76°
and volatilizes without decomposition.

ESTERS OF ARSENIC ACIDS.

Ethyl Arsenate, AsO(O.C2H5)3, is the product of the action of ethyl iodide
upon silver arsenate, AsO^Agj. It is a liquid, boiling at i'^^.

The esters of arsenious acid, As(0H)3, form when AsBr3 is distilled with
sodium alcoholates. They distil without decomposition. Water immediately
changes them to arsenious acid and alcohols. The methyl ester, As^O.CHj),,
boils at 128°; the ethyl ester at 166°.

Arsenic compounds analogous to the phosphorous and phosphinic acids,
C2H5.PO(OH^2 and (C2H5)2PO.OH, exist. They are: methyl arsinic acid,
CH3.AsO(OH)2, and dimethyl arsinic acid, (CH3)2AsO.OH, or c^codylic acid.
These will be considered with arsenic alcoholic radicals.

ESTERS OF SILICIC ACIDS,

These are obtained by the action of SiCl^ and SiFl^ upon alcohols or sodium
alcoholates. The esters of normal silicic acid, Si(OH)4, of metasilicic acid,
SiO(OH)2, and disilicic acid, SijO^Hj, are formed together and can be separated
by fractional distillation.

The normal Methyl Ester, Si(0.CH3)^, boils at 120-122°; methyl disilicafe,
Sij0,(CH3)3,at?o2°.

The Ethyl Ester,S\{0.C^'R^)^,hoi\s3)iies°. Ethyl disilicate, Si^O^iC^li^)^,
which can also be produced by action of silicon oxychloride, SijOClj, on ^cohol,
boils at 236°; ethyl-metasilicate,SiO.(O.C2H5)2, boils at 360°-

These derivatives on standing awhile in moist air, or by addition of water, slowly
decompose with separation of silicic acid, which sometimes solidifies to a trans-
parent hard glass.

AMINES. 157

AMINES.

Among the derivatives of carbon exists a series of very basic
bodies, which have been designated organic bases or alkaloids.
They all contain nitrogen and are viewed as ammonia derivatives ;
this accounts for their basic character. We will consider here only
the monatnines derived from ammonia by the replacement of hydro-
gen by monovalent alkyls.

One, two and three hydrogen atoms of the ammonia molecule
may suffer this replacement, thus yielding the primary, secondary
and tertiary amines (also called amide, imide, and nitrile bases): —

N-H

N— C.H^

N— C2H5

\H

Ethylamine.

\H

Diethylamine.

\C,H,.

Triethylamine.

Derivatives also exist that correspond to the ammonium salts and
hypothetical ammonium hydroxide, NHi.OH: —

(CaH5)^NCl (C,H5)^N.0H.

Tctra-ethyl Ammonium Chloride. Tetra-etliyl Ammonium Hydroxide.

The following methods are the most important for preparing the
above compounds :^-

(i) The iodides or bromides of the alcohol radicals are heated
to 100°, in sealed tubes, with alcoholic ammonia (A. W. Hofmann,
1849). In this way the alkyl displaces the hydrogen of amnionia ;
the hydrogen haloid formed at the same time combines with the
amine and yields ammonium salts : —

NH3 + C2H5I = NH JC2H5).HI
NH3 + aCjHsI = NH(C,HJ,.HI + HI
NH3 + 3c'h,I = N{C,H,),.HI + 2UI.

When these salts are distilled with sodium or potassium hydroxide,
free amines pass over : —

NH(C,H5),.HI + KOH =• NHCC.Hs)^ + KI + H,0.

It is interesting to know that the primary alkyl iodides form both secondary and
tertiary amines, while the secondary alkyl iodides (like isopropyl iodide) only
furnish primary amines (also alkylens) (Berichte, 15, 1288).

In the same process tertiary amines further unite with alkyl
iodides and form tetra-alkyl ammonium salts: —

N(C,H5)3 + C,H J = N(C,H5) J.

IS 8 ORGANIC CHEMISTRY.

These are not decomposed when distilled with KOH; but if
treated with moist silver oxide they yield ammonium hydroxides : —

N(C,H5) J + AgOH = N(C,H,),.OH + Agl.

B/ the action of primary alkylogens upon ammonia, a mixture of primary,
secondary and tertiary amine salts and those of the ammonium bases, always
results. The latter may be easily obtained pure by distilling the inixture with
KOH, when the amines pass over and the ammonium bases mike up the residue,
inasmuch as their halogen compounds are not decomposed by alkalies.

Fractional distillation is a poor means of separating the amines. The follow-
ing procedure serves this purpose better (Berichte, 8, 760) : The mixture of the
dry bases is treated with diethyl oxalate, when the prinjary amine, e. g., methyl-
amine, is changed to diethyl oxamide, which is soluble in water ; dimethylamine
is converted into the ester of dimethyl oxamic acid (see oxalic acid compounds) ;
and trimethylamine is not acted upon : —

2NH,{CH3) + C,0,/g;g^^2= = C,0,/NH.CH, ^ 2C,H,.0H.

Diethyl Oxalate. Dimethyl Oxamide.

NH(CH3), + C,0,/O.C,H, _ (,^Q^/O.C,H ^ c,H,.OH.

Bimethyl-oxamic Ester.

When the reaction-product is distilled the unaltered trimethylamine passes
over. Water will extract the dimethyl oxamide from the residue ; on distillation
with caustic potash it becomes methylamine and potassium oxalate : —

^»°»\NH:ch', + 2K0H = C30,K, +2NH,(CH.).

The insoluble dimethyl.oxamic ester is converted, by distillation with potash,
into dimethylamine : —

C2O2 (^n'cc'h,'), + 2^0^ = C2O4K, + NH(CH3), + C,H,.OH.

Another procedure furnishing a partial separation of the amines depends on
their varying behavior towards carbon disulphide. The free bases (in aqueous,
alcoholic or ethereal solution) are digested with CS^, when the primary and
secondary amines form salts of the alkyl dithio-carbaminic acids (see these), while
the tertiary amines remain unafiected, and may be distilled off. On boiling the
residue with HgClj or FeClj, a part of the primary amine is expelled from the
compound as mustard oil (^Berichte, 14, 2754 and 15, 1290).

The esters of nitric acid, when heated to 100° with alcoholic
ammonia, react in a manner analogous to the alkyl iodides : —

C.H^.O.NO^ + NH3 =C2H,.NH, +HNO3.

This reaction is often very convenient for the preparation of the
primary amines (Berichte, 14, 421).

Mono-, di-, and tri-alkylamines are obtained by directly heating the alcohols to
250-300° with zinc-ammonium chloride {Berichte, 17, 640). -

AMINES. 159

(^2) The ethers of isocyanic or isocyanuric acid are distilled with
potassium hydroxide (^Wilrtz, 1848): —

COtN.CHj + 2KOH = NH2.CH3 + CO3K2.

Cyanic acid is changed to ammonia in precisely the same man-
ner:—

CO:NH + 2KOH = NH3 + COjKj.

In the above reaction only primary amines are produced.

To convert alcoholic radicals into corresponding amines, the iodides are heated
together with silver cyanate ; the product of the reaction is then mixed with pul-
verized caustic soda, and distilled in an oil bath [Berichte, 10, 131).

Above we observed the decomposition of the isocyanic ethers by
alkalies. Their analogues in constitution — the isothio-cyanic ethers
(the mustard oils, etc.,) — are also broken up into primary amines
by sulphuric acid.

3. Warm the isocyanides of the alkyls with dilute hydrochloric acid; formic
acid will split off (^. W. ffofmann): —

CjH5.NC + 2H,d = C2H5.NH, + CH,0,.

The isocyanides are obtained by heating the alkyl iodides with silver cyanide
(see these).

J 4) By the action of nascent hydrogen upon the nitriles or alkyl cyanides
endius) : — ■

HCN + 2Hj = CH3.NH,.

Hydrogen Cyanide. Methylamine.

CH3.CN + 2Hj = CH3.CHj.NHj.

Acetonitrile. Ethylamine.

A more advantageous course consists in allowing metallic sodium
to act upon the nitrile dissolved in absolute alcohol. In this way
the dicyanides can be converted into diamines (^Berichte, 18, 2957 ;
19, 783 ; 22, 8i3).

(5) By action of nascent hydrogen (HCl and Zn) upon the nitro-paraffins
^^ ' CHj.NOj + 3Hj = CHj.NHj -j- 2HjO.

(6) A method entirely new, and especially adapted to the forma-
tion of primary amines, consists in the transformation of fatty acids
{A. W. Hofmann, Berichte, 15, 762). The amides of these acids
are converted, through the agency of Br and KOH, mto brom-
amides : —

CjH5.CO.NHj -H Brj + KOH = CjH5.CO.NHBr -I- KBr -|- HjO.

l6o ORGANIC CHEMISTRY.

On further heating with alkali, carbon dioxide escapes and
primary amines result : —

CjH5.C0.NHBr+ 3KOH = CjH^.NHj + CO.Kj + KBr + HjO.

When I molecule bromine and 2 molecules of the amide react, the product con-
sists of mixed ureas : —

/NH.CO.CHj
2CH3.CO.NH. + Br, = CO + 2HBr.

\NH.CH3

Methyl Aceto-urea.

The fatty-acid amides, with more than 5 C-atogis, not only yield amines, but also
large quantities of the nitriles of the next lower acids : —

CgHi,.CO.NH2 yields CjHu.CN.

In this way CO is eliminated, and amines form. These yield dibromides with
bromine, and by the further action of KOH are changed to nitriles (Berichte, 17,
1406, 1920) : —

CjH^.NBr^CCjHij.CH.NBr,) yields CjHij.CN.

These reactions are also adapted to the conversion of acid amides of the benzene
series into amines {Berichte, 18, 2734, and ig, 1822).

(7) For the conversion of the aldehydes and ketones into their
corresponding primary amines, their phenylhydrazine derivatives
are treated with nascent hydrogen j best by the action of sodium
amalgam and glacial acetic acid upon the alcoholic solutions {Be-
richte, 19, 1925; 22, 1854): —

CH3.CH:N,H.C,H5 -f 2H, = CHj.CH^.NH, -]- C.H^.NH^.

The primary amines can also be obtained, in a similar manner,
from the hydroxylamine derivatives of the aldehydes and ketones
(see the aldoximes and acetoximes) {Berichte, 19, 3232).

The methods above are those ordinarily employed; others exist
for the production of amines ; e. g., they arise in the decomposition
of complex nitrogenous derivatives, as shown in the case of the
amido-acids.

Tertiary, secondary and primary amines may also be obtained by
the dry distillation of the halogen salts of the ammonium bases : —

CI =N(CH,), +CH3CI
HCl = NH(CH3)j + CH3CI
)fi.CX = NH2(CH3) + CH3CI, etc.

These reactions . serve for the commercial production of methyl
chloride from trimethylamine.

On a large scale, the amines are best prepared by acting on the
alkyl bromides with ammonia (Berichte, 22, 700).

AMINES. l6l

The amines are very similar to ammonia in their deportment.
The lower members are gases, with ammoniacal odor, and are very
readily soluble in water; their combustibility distinguishes them
from ammonia. The higher members are liquids, soluble in water,
and only the highest are sparingly soluble. The amines are best
dehydrated by distillation over barium oxide. Their basicity is
greater than that of ammonia, and increases with the number of
alkyls introduced ; the tertiary amines are stronger bases than the
secondary, and the latter stronger than the primary. Therefore,
they can expel ammonia from the ammonium salts. Like ammonia,
they unite directly with acids to form salts, which differ from
ammoniacal salts by their solubility in alcohol. They combine
with some metallic chlorides, and afford compounds perfectly analo-
gous to the ammonium double salts; e. g. : —

[N(CH,)H3Cl],PtCl4. N(CH3)H3Cl.AuCV [N(CH3),nCl],HgCl,.

The ammonia in the alums, the cuprammonium salts and other
compounds may be replaced by amines.

The behavior of amines with nitrous acid is very characteristic.
The latter compound converts the primary amines (better to act on
the haloid salts with AgNOj) into the corresponding alcohols (see
p. 122): —

C^Hj.NHj + NO.OH = CjHj.OH + N^ + H^O.

This is a reaction analogous in every respect to the decomposition
of ammonium nitrite into water and nitrogen : —

NH3 + NO.OH = nfi + N2 + HjO.

Nitrous acid changes the secondary amines into nitroso-amines

(p. 164) : —

(CH3),NH + NO.OH = (CH3),N.N0 + H,0.

Nitroso-dimethylainine.

The tertiary amines remain intact or suffer decomposition. These
reactions may also be employed to effect the separation of the amines.

When aided by heat KMnO^ breaks up the amines, nitrogen being eliminated
and the alkyls being oxidized to aldehydes and acids {Berichte, 8, 1237).

Bromine in alkaline solution converts the primary amines (their HCl-salts) into
alkylized nitrogen dibromides, e.g., CjH^.NBrj, the secondary amines at the
same time throw off alkylen bromides and become primary ammes {Benchie, 16,

558):—

' (C,H5)3NH + Br, = C^H^-NH, + C.H^Br,.

The alkalies change the bromides of the higher alkylamines into
nitriles (p. 160). Well characterized compounds are those obtamed
by the action of dinitrochlorbenzene upon the primary and secondary
amines {^Berichte, 18, Ref. 540).
14

l62 ORGANIC CHEMISTRY.

The possible isomerides of the amines are very numerous ; they
are determined not only by the isomerism of alcoholic radicals, but
also by the number of replacing groups, as is manifest from the fol-
lowing examples : —

fC.H, fC.H^ fCH,

1h 1h ICH,.

Propyl and Methyl. Trimethyl-

Isopropylamine. ethylamine. amine.

They are thus distinguished : by the action of ethyl iodide the
primary amines can receive two, the secondary, however, only one
additional ethyl group, while the tertiary amines form ammonium
bases directly. The power of forming carbylamines and mustard
oils (see these) is especially characteristic of the primary amines ;
these are easily recognized by their odor {Berichte, 8, 108 and 461).

PRIMARY AMINES.

Methylamine, CH3.NH2, is produced when the methyl ester of
cyanic acid is heated with potash (p.. 159); by the action of tin
and hydrochloric acid upon chloropicrin, CCl3(N02) ; when nascent
hydrogen acts upon hydrogen cyanide ; and by the decomposition
of various natural alkaloids, like theine, creatine, and morphine.
The best way of preparing it is to warm brom-acetamide with
caustic potash (see p. 159 and Berichte, 14, 764) : —

CH,.CO.NHBr + 3KOH = CH5.NH2 + CO5K2 + KBr + H^O.

Methylamine is a colorless gas, with an ammoniacal odor ; it con-
denses to a liquid at — r6°. Its combustibility in the air distin-
guishes it from ammonia. At 12" i volume of water dissolves 1150
volumes of the gas. The aqueous solution manifests all the proper-
ties of aqueous ammonia, but does not, however, dissolve the
oxides of cobalt, nickel and cadmium. Iodine (also Br) throws
out a dark red precipitate, CH3.NI2, from the solutions of methyl-
amine : —

2CHa.NH2 + 2I2 = CHj.NIj + 2CH8.NHj.HI.

When methylamine is conducted over heated potassium it decom-
poses into potassium cyanide and hydrogen : —

CHj.NHj + K = CNK + sH.

The salts of methylamine are soluble in water. Its hydrochloride crystallizes
in large, deliquescent leaflets, fusing at 100° and distilling without decomposition.
It yields a yellow, crystalline, double salt— [NH2(CH3)HCl]j.PtCl4— with
PtCl^. Its double salt with auric chloride crystallizes in needles.

SECONDARY AMINES. 1 63

Ethylamine, CjHj.NHj, is a mobile liquid, that boils at i8°
and has a sp. gr. of 0.696 at 8°. It mixes with water in all propor-
tions. It expels ammonia from ammoniacal salts, and when in ex-
cess redissolves aluminium hydroxide ; otherwise it deports itself in
every respect like ammonia.

Its hydrochloride, NH8(C2H5)C1, crystaUizes in large, deliquescent leaaets,
fusing at 80°. Its platinum double salt crystallizes in orange-red rhombohedra.
Like ammonia, it also combines with PtClj to form PtCl2(C2H5.NH2)2. It exists
as a white mass when in union with COj, and in this condition if added to aBaCl,
solution it gradually precipitates barium carbonate. It probably corresponds to
ammonium carbaminate.

/3-Brom-Ethylamine, CHjBr.CHj.NHj, is formed from brom-ethyl-phthalimide
by the aid of HBr. Its hydrobromic acid salt melts at 155° (Berichte, 21, 566).
Silver oxide or KOH converts the latter into Vinylamine. For further derivatives
consult Berichte, 22, 1139, 2222.

Propylamine, CgHj-NH,, boils at 49°; isopropylamine, CjH^.NH^, is
most readily obtained by the reduction of dimethyl acetoxime, (CH5)jC|N.OH
(see p. 160) ; it boils at 3l°-32°. (Berichte, 20, 505.)

Butylamine, C^Hj.NHj (normal), boils at 76°; isobutylamine, C^Hj.NHj,
obtained from fermentation butyl alcohol and from ordinary valeramide, boils
at 66°.

Normal Amylamine, C.H,,.NHo, from normal caproylamide, C=H„.
CO.NH2,boils at 103°.

Isoamylamine, C5H11.NH2, is a liquid boiling at 95°; it is obtained from
leucine by distillation with caustic potash, or from isocaproylamide. It is miscible
with water, and bums with a luminous flame. Nonylamine, C9Hjg.NH2, ob-
tained from normal caprylamide, boils about 195°, and is sparingly soluble in water.
The higher alkylamines, containing an odd number of C-atoms, are most readily
obtained by the action of sodium in alcoholic solution upon the nitriles of the
fatty acids, CnH2n.CN — (see p. 159 and Berichte, 22, 812); while those with an
even number of carbon atoms are produced by the action of bromine, in alkaline
solution, upon the acid amides (p. 159 and Berichte, 21, 2486).

Vinylamine, CJH3.NH2 (p. 134), results when silver oxide, or potassium hy-
droxide, acts upon bromethylamine. It is only known in solution. When evapo-
rated with concentrated hydrochloric acid it yields chlorethylamine, C2H4CI.NH2.
It forms taurine, CH3(NH2).CH3.S03H, with sulphurous acid, amido-ethyl-
sulphuric acid with H^SO^, and oxy- ethylamine, CHj.(NH2).CH2.0H (Berichte,
21, 2664) with water (by the action of nitric acid).

AUylamine, C5H^.NH2, is obtained by the action of concentrated sulphuric
acid, or zinc and hydrochloric acid, upon mustard oil (C3H5.N:CS) ; it is a liquid
boiling at 58°.

Brom-allylamine, CgH^Br.NHj is obtained from the dibromide of allyl-
amine. It boils at 125° (Berichte, 21, 3190.)

SECONDARY AMINES.

Dimethylamine, NH(CH3)2, is a gas that dissolves readily in
water. It is condensed to a liquid by cold, and boils at 7.2°. It is
most conveniently obtained by boiling nitroso-dimethyl aniline or
dinitro-dimethyl aniline with caustic potash {Annalen, 222, 119).
The platinum double salt crystallizes in large needles.

164 ORGANIC CHEMISTRY.

Diethylamine, NHCQHj),, is a liquid boiling at 56° and is
readily soluble in water. Its HCl-salt fuses at 216° and boils at
325°-

The secondary amines are also designated imide-bases.

Sulphamides, <. ^., SOa/^i^^']'" are formed by the action of sulphuiyl

chloride, SO2CI2, upon the free secondary amines, whereas their chlorides,

SO 2 ^ p, ^ , result when the HCl-salts are employed. Water converts the chlorides

into sulphaminic acids, SOj/qjt^ (^««a/if», 222, 118). SO3 reacts similarly

with the primary and secondary amines, forming mono- and dialkyl-sulphaminic
acids ( Berichte, 16, 1265).

Nitroso-amines. These are compounds having the nitroso-group attached to
N (p. 106). All basic secondary amines (imines), like (CHj)2NH and

P A f^ /NH, can become nitroso-amines through the replacement of the hydro-
gen of the imide group. They are obtained from the free imides by the action of
nitrous acid upon their aqueous, ethereal, or glacial acetic acid solutions, or by
warming their salts in aqueous or acid solution with potassium nitrite (^Berichte,
g, 112). They are mostly oily, yellow liquids, insoluble in water, and maybe
distilled without suifering decomposition. Alkalies and acids are usually without
effect upon them ; with phenol and sulphuric acid they give the nitroso reaction
(see p. 107). When reduced in alcoholic solution by means of zinc dust and
acetic acid they become hydrazines (p. 1 66). Boiling hydrochloric acid decom-
poses them into nitrous acid, and dialkylammes.

Dimethyl Nitrosamine, (CHj)2N.N0, is a yellow oil, of penetrating odor.
It boils at 148°.

Diethyl Nitrosamine, (C2H5)2N.NO, is also an oil, boiling at 177°; it is ob-
tained from HCl-diethylamine by distilling it with KNO2 in aqueous solution.
Concentrated hydrochloric acid regenerates diethylamine from it.

Nitroamines, containing the nitro-group in union with nitrogen, are produced
by the action of concentrated nitric acid upon various amide derivatives {^Berichte,
18, Ref. 146; 22, Ref. 295).

Methyl-nitramine, CH3.NH(N02), from the esters of methyl carbaminate,
melts at 38°. It has an acid reaction. Ethylnitramine, C2H5.NH(N02),
from ethyl carbaminate, solidifies on cooling, and melts at 3°, Dimethyl-hitra-
mihe, (CHj)2.N(N02), is formed by the action of potassium hydroxide and
methyl iodide upon methylnitramine. It melts at 58°, and boils at 187° (^Berichte,
32, Ref. 296).

TERTIARY AMINES.

Trimethylamine, N(CHs)3. This is isomeric with propyl-
amine, CaHj.NHj, and is present in herring-brine ; it is produced
by distilling betame (from the beet) with caustic potash. It is
prepared from herring-brine in large quantities, and also by the
distillation of the "vinasses" of the French beet root. Trimethyl-
amine is a liquid, very soluble in water, and boils at 3.5°. The

AMMONIUM BASES. 165

penetrating, fish-like smell is characteristic of it. Its HCl-salt is
very deliquescent.

Triethylamine, N(C2H5)3, boils at 89° and is not very soluble in water. It
is produced by heating ethyl isocyanate with sodium ethylate: — CO:N.C,H. +
2C,H..ONa = N(C,H,)3 + COjNa,.

AMMONIUM BASES.

The tertiary amines combine with alkyl iodides and yield am-
monium iodides ; these are scarcely affected by the alkalies, even on
boiling (p. 158) ; but when treated with moist silver oxide the am-
monium hydroxides are formed : —

N(C,H5) J + AgOH = N(C,H5)^.0H + Agl.

These hydroxides are perfectly analogous to those of potassium
and sodium. They possess strong alkaline reaction, saponify fats,
and deliquesce in the air. They crystallize when their aqueous
solutions are concentrated in vacuo. With the acids they yield
ammonium salts ; these usually crystallize well.

On exposure to strong heat they break up into tertiary amines and
alcohols, or their decomposition products (QHan and HjO) : —

N(C,H5),.0H= NCC.H^), + C.H^ -f H,0.

If the ammonium base contains different alkyls, it is usually the ethyl group that
is split off {Berichte, 14, 494).

If iodine is added to the aqueous solution of the iodides, com-
pounds are precipitated which contain three and five atoms of
iodine: (C,H5)iNI.l2 and (S^^^$il.2\.

The tri-iodides are mostly dark violet bodies ; the penta-iodides
resemble iodine very much.

Tetraethyl Ammonium Iodide, N(C2H5)4l, is obtained by mixing triethyl-
amine with ethyl iodide ; the mixture becomes warm and when it cools is crys-
talline. It separates from water or alcohol in large prisms, that fiise when heated,
and then decompose into N(C2Hg)3 and CjHgl. Moist silver oxide converts
it into

Tetraethyl Ammonium Hydroxide, N(C2H5)40H, which crystallizes • in
delicate, deliquescent needles. It absorbs COj from the an- with avidity. Its
platinum double salt, [N(C2H5)4Cl]j.PtCl4, crystallizes in octahedrons.

Tetraethyl Ammonium Cyanide, {<Z^\^)^.Z'ii, is a white, crystalline
mass. It is obtained by acting on the hydroxide with HCN, or upon the iodide
with barium cyanide. When boiled with alkalies it decomposes into NH 3, formic
acid and ammonium hydroxide. (CVi \ 1

Dimethyl-diethyl Ammonium Chloride, \ jj3/2 jNCl, is obtained from

dimethylamine and ethyl iodide, and from diethylamine and methyl iodide : —

CH3 !-N.C,HJ and C^Hj J- N.CHjI.
C,H,

, In.CjHJ and CjHs^N.C
i J CH3 J

l66 ORGANIC XHEMISTRY.

These two compounds are identical (Annalen, i8o, 273). They
demonstrate, too, that the ammonium compounds are not molecular
derivatives as formerly assumed (the above formulas are only intended
to exhibit the different manner of formation), but represent true
atomic compounds. They further show the equivalence of the five
nitrogen valences (compare Le Bel, Berichte, 23, Ref. 147).

HYDROXYLAMINE DERIVATIVES.

The amines are derived from ammonia. Hydroxylamine also yields a series of
analogous alkyl compounds, very similar to the amines. The entrance of one
alkyl group produces two isomeric forms : —

(a) NHj.O.CHj and (/3) CH.,.NH.OH.

Hydroxylamine Ether. Alkyl Hydroxylamine.

The derivatives of the first modification are also called Alkylhydroxylamines.
They result fi-om the decomposition of the ethers of os-benzaldoxime, e. g.,
CjHj.CH: N.O.CH3, on digesting them with acids, or from the esters of ethyl-
benzhydroxamic acid (see this) {Berichte, 16, 827 ; 22, Ref 587). The /?-alkyl-
hydroxylamines seem to be similarly derived from the ethers of /3-benzaidoxime
{Berichte, 23, S99).

a-Methylhydroxylamine, NHj.O.CHj, Methoxylamine, prepared by the first
two methods, yields an HCl-salt, which melts at 149°. It differs from hydroxyl-
amine in that it does not reduce alkaline copper solutions.

P-Methylhydroxylamine, CH,.NH.OH(?), from the methyl ether of ;8-isoben-
^aldoxime, forms an HCl-salt, melting at 85-90°.

a-Ethylhydroxylamine, NH2.0.C2H5(?), Ethoxylamine, derived from ethyl-
benzhydroxamate, is a liquid, boiling at 68°. The compound obtained firom ethyl-
benzaldoxime has not been accurately studied (Berichte, 16, 829).

The action of ethyl bromide upon ethoxylamine produces Diethylkydroxylamine,
CjHj.NH.O.CjHj, and Trietkylhydroxylamine, (C2H5)2.N.O.C2H5, boiling at
98° {Berichte, 22, Ref. 590). An isomeridfi of the latter has been prepared by
the interaction of zinc ethide and nitro-ethane. It boils at 155° {Berichte, 22,
Ref. 250).

HYDRAZINES.

Just as the amines are derived from ammonia, NH3, so the hydra-
zines are derived from hydrazine or diamide, H^N — NHj, an ana-
logue of liquid hydrogen phosphide, HjP — PHj, and dimethyl-
arsine (cacodyl), (CH3)2A? — As(CH3)2.

The preparation of hydrazine in a free state is of recent date. It
has been obtained from diazo-acetic acid (see this). Its deriva-
tives, however, have been known for quite a long time, and have
been prepared by a variety of methods. They hold an important
place in the benzene series (see phenyl hydrazine, CeHj.NH.NHa)
(E. Fischer, Annalen, gg, 281).

The mono- and dialkyl hydrazines are at present the only known
derivatives.

HYDRAZINES. 167

In physical and chemical properties they closely resemble the
amines, but are distinguished from them by their ability to reduce
alkaline copper solutions. They are powerful bases, uniting with
one and two equivalents of acids to form salts.

The mono-alkyl hydrazines are obtained from the mono-alkyl ureas, NHj.CO.
NH.R, and from the symmetrical dialkylureas by their conversion into nitroso-
compounds, and the reduction of the latter to hydrazines of the ureas : —

CH,NH\„Q . ,, CH3.NH\p„ CHj.NHX™

\NO \NH

When the latter are heated with alkalies or acids they split up, like all urea deriva-
tives, into their components, COj, alkylamine and alkylhydrazine.

Methyl Hydrazine, CHg.NH.NHj, from methyl urea, is a very mobile liquid,
boiling at 87°. Its odor is like that of methylamine. In the air it absorbs moist-
ure and fiimes {Berichte, 2a, Ref. 670).

Ethyl Hydrazine, (CjHjjHN.NH^, obtained from diethyl urea, is perfectly
similar to the methyl derivative. It boils at 100°. Both compounds reduce
Fehling's solution in the cold.

When ethyl hydrazine is acted upon by potassium disulphate, and the product
treated with monopotassium carbonate, potassium ethyl hydrazine sulphonate,
CjHj.NH — NH.SO3K, is formed. Mercuric oxide changes this to potassium
diazo-ethy I sulphonate, C2Hj.N = N.S03K. This is the only well-known repre-
sentative in the fatty-series of a numerous and highly important class of derivatives
of the benzene series — the diazo-compounds. They are characterized by the diazo
group, — N=N — , which is in union with carbon radicals.

Dialkylhydrazines, like (CH3)2N.NHj, are formed by the reduction of
nitroso-amines, in aqueous and alcoholic solution, by zinc dust and acetic acid : —

(CH3),N.N0 + 2H, = (CH3),N.NH, + H,0.

C H \
Nitroso-amines containing at the same time acid radicals, e.g., p A q yN.NO, do

not yield corresponding hydrazines, but revert to amides. 23/

Dimethyl Hydrazine, (CH3)2N.NH2,and Diethyl Hydrazine, (CjHJjN.

NH2, are mobile liquids, of ammoniacal odor, and readily soluble in water, alcohol

and ether. Diethyl hydrazine boils at 97°, and the dimethyl compound at 62°.

They reduce Fehling's solution when warm.

Diethylhydrazine unites with ethyl iodide and yields the compound (CjHs)^.

V NH,

N.NHj.CjHjI, which is to be viewed as the ammonium iodide, (CjH5)3N^

■■■I

as it is not decomposed by alkalies, and moist silver oxide converts it into a strong

alkaline hydroxide. Nascent hydrogen (zinc and sulphuric acid) decomposes this

iodide in the manner indicated in the following equation : —

(C,H,)3n/ ' + 2H = {C,H,)3N + NH3 + HI.

This reaction is an additional proof that the ammonium compounds represent
atomic derivatives of pentavalent nitrogen (Annalen, 199, 318). When mercuric
oxide acts upon diethylhydrazine /«/>-3«««^,(C2H5)jN.N:N.N(C2H5)2, is formed.
This is a strong basic liquid with an alliaceous odor.

l68 ORGANIC CHEMISTRY.

PHOSPHINES OR PHOSPHORUS BASES.

Hydrogen phosphide, PHj, has slight basic properties. Its
compound with HI — phosphonium iodide, PHJ — is not very
stable. Through the introduction of aikyls (alcohol radicals), it
acquires the strong basic character of ammonia ; its derivatives —
the phosphines or phosphorus bases — correspond perfectly to the
amines.

When the alkyl iodides act upon phosphine, tertiary phosphines
and phosphonium iodides (Th6nard) are the sole products : —

PH3 + 3C,H,I = P(C,H5)3.HI + 2HI, and
P(C,H3)3 + C,H,I = P(C,H5) J.

It was A. W. Hofmann (1 871) who prepared the Jirimary and secondary deri-
vatives by letting the alkyl iodides act upon phosphonium iodide in the presence of
certain metallic oxides, chiefly zinc oxide, the mixture being at the same time heated
to about 150°. This procedure yields a mixture of the two classes (their HI
salts) : —

2PH J + aCjH^I + ZnO = 2P(C2H5)Hj.2HI + Znl, + H.O, and
PH J + 2C,H5l + ZnO = P(C2H5),H.HI + Znl, + H,0.

Water releases the monophosphine from the crystalline mass : —

V{C^-ii,)n,l + H,0 = P(C,H3)H, + HI + H,0.

This is like the decomposition of PH^I by water into PHj and HI. The HI
salt of the diethylphosphine is not affected. But by boiling the latter with sodium
hydroxide, diethylphosphine is set free.

Thinard (1846) first discovered the tertiary phosphines by acting upon calcium
phosphide with alkyl iodides. They also result when zinc aikyls are brought in
contact with phosphorous chloride : —

2PCI3 + 3(CH3),Zn = 2P(CH3), + sZnCl,,

and upon heating the alkyl iodides to 100° with amorphous phosphorus. The
easiest course is to heat phosphonium iodide with alkyl iodides to I5o°-l8o°,
whereby phosphonium iodides are produced at the same time : —

PH,I + 3CH3I = P(CH3)3.HI + 3HI, and
P(CH3)3HI + CH3I =P(CH3)J +HI.

If these be digested with potassium hydroxide, the tertiary phosphine is elim-
inated, while the iodide of the phosphonium base is unaltered (the case with the
amines).

The phosphines are colorless, strongly refracting, extremely powerful-smelling,
volatile liquids. They are nearly insoluble in water. On exposure to the air they
are energetically oxidized and usually inflame spontaneously ; hence, they must be
prepared away from air contact. They combine readily with sulphur and carbon
disulphide. They form salts with the acids. Primary phosphines are very slightly
basic, therefore, water decomposes their salts (see above).

PHOSPHINES OR PHOSPHORUS BASKS, 1 69

PRIMARY PHOSPHINES.

Methyl Phosphine, P(CH3)H2, is a gas, condensing at — 20° to a mobile
liquid. It is readily soluble in alcohol and ether. Concentrated hydrochloric
acid does not decompose its HCl-salt, P(CH„)H2.HC1. It yields a double salt
with platinic chloride. Fuming nitric acid oxidizes it to methyl phosphinic acid,
CHj.PO.COH^) (p. 156).

Ethyl Phosphine, FiC^il^)}^^, boils at + 25° and swims upon water. It is
very energetically oxidized by air contact, and ignites when brought near chlorine
and bromine. Its platinum double salt consists of red needles.

Isopropyl Phosphine, P(C3H,)H2, boils at 41°, and the isobutyl deriva-

SECONDARY PHOSPHINES.

Dimethyl Phosphine, P(CH3)2H, boils at 25° C, and takes fire on exposure
to the air. Concentrated nitric acid converts it into dimethyl phosphinic acid,
(CH3)jPO.OH (p. 156).

Diethyl Phosphine, P(C2H5)2H, boils at 85° and inflames spontaneously.
Nitric acid oxidizes it to diethyl phosphinic acid (C2H5)2PO.OH.

Di-isopropyl Phosphine, P(C3H,)2H, boils at 118°. Di-isoamyl Phos-
phine, P(C5Hii)2H, boils at 2lo°-2i5°, fumes in the air, but is not self-inflam-
mable.

Water does not decompose the salts of the secondary phosphines. The HI
salts and the double salts with platinic chloride are prepared with the least difiS-
culty.

TERTIARY PHOSPHINES.

Trimethyl Phosphine, P(CH3)3, is prepared by heating carbon
disulphide with phosphonium iodide. It is a colorless, very dis-
agreeably smelling liquid, which will swim upon water. It boils at
40°- It fumes in the air, absorbing oxygen and igniting. When
slowly oxidized it changes to trimethyl phosphine oxide, P(CH3)30,
which forms crystals that are deliquescent in the air. Sulphur will
dissolve in the base and give a crystalline sulphide, P(CH3)3S.
It combines in a like manner with the halogens, their hydrides, and
also with CSj. It yields salts with the acids ; these are very soluble
in water.

Triethyl Phosphine, P(CjH5)3, is analogous to the above compound. It
boils at 117°, and has a specific gravity of 0.812 at 15°. It has a neutral reac-
tion. It dissolves slowly in acids, yielding salts. Its platinum double salt,
[P(C2H5)3HCl]2.PtCl4, is sparingly soluble in water and crystallizes in red
needles. It forms crystalline halogen derivatives, P(CjH5)3X2.

Triethyl Phosphine^Oxide, P(C2H5)30, results from the slow oxidation of
phosphine in the air, and by the action of mercuric oxide : —

P(C2H3)3 + HgO = nC,U,),0 + Hg.

It forms deliquescent needles, melting at 53°, and distilling without decompo-
sition at 243°. With the haloid acids it yields dihaloids, «.^., P(C2H5)3Cij
from which triethyl phosphine is produced on warming with sodium.

170 ORGANIC CHEMISTRY.

Triethyl phosphiae dissolves sulphur to form a sulphide, P^CjjH5)3S, which
crystallizes from water in brilliant needles, fusing at 94° and distilling about 100°.
Mercury or lead oxide converts it into the oxide. Carbon disulphide also com-
bines with triethyl phosphine, and the product is P(C2H5)3.CS2, crystallizing in
red leaflets. It is insoluble in water, fuses at 95°, and sublimes without decom-
position.

According to almost all these reactions, triethyl phosphine resembles a strongly
positive bivalent metal ; for example, calcium. By the addition of three alkyl
groups, the pentavalent, metalloidal phosphorus atom acquires the character of
a bivalent alkaline earth metal. By the further addition of an alkyl to the phos-
phorus in the phosphonium group, P(CHj)^, the former acquires the properties of a
monovalent alkali metal. Similar conditions manifest themselves with sulphur,
with tellurium, with arsenic, and also with almost all the less positive metals.

PHOSPHONIUM BASES.

The tertiary phosphines combine with the alkyl iodides to form phosphonium
iodides, not decomposed by alkalies : —

P(CH3), + CH3l = P(CH3)J.

If, however, the iodides be treated with moist silver oxide the phosphonium
iases result : —

P(CH,) J + AgOH = P(CH,)^.OH + Agl.

These are perfectly analogous to the ammonium bases ; they react alkaline, ab-
sorb carbon dioxide, and saturate the acids to form salts. When strongly heated
they break up into phosphine oxide and hydrocarbons of the paraffin series : —

P(CH3)^.0H = P(CH3)30 + CH^.

Tetraethyl Phosphonium Iodide, P(C2H5)^I, consists of very soluble,
white needles. When heated these decompose into P(C2Hg)3 and C^HjI.

Tetraethyl Phosphonium Hydroxide, P(C2H5)^.OH, is a crystalline com-
pound that .deliquesces on exposure. With acids it forms crystalline salts. The
platinum double salt cirystallizes in orange-red octahedra.

ARSENIC BASES.

Arsenic is quite metallic in its character; its alkyl compounds
constitute the transition from the nitrogen and phosphorus bases to
the so-called metallo -organic derivatives, i. e., the compounds of the
alkyls with the metals (p. 177). The similarity to the amines and
phosphines is observed in the existence of tertiary arsines, As(CHs)3,
but these do not possess basic properties, nor do they unite with
acids. They show in a marked degree the property of the tertiary
phosphines, in their uniting with oxygen, sulphur and the halogens,

TERTIARY ARSINES AND ARSONIUM COMPOUNDS.

171

to form compounds of the type As(CH3)aXj. They yield arsonium
todtdes with the alkyl iodides, : —

MCH3), + CH3I = As(CH3) J,

and these in turn become hydroxides by the action of moist silver
oxide: —

MCH3) J + AgOH = As(CH3)^.0H + Agl.

These hydroxides are analogous to the ammonium and phospho-
nium bases ; they are very alkaline and yield salts with acids.

The arsines analogous to the primary and secondary amines and
phosphines, such as As(CH3)H, and As(GH3)2H, are unknown, and
probably cannot exist. Through an accumulation of alkyls, arsenic,
like the metals, receives a more positive character; As(CH3)jCl
and As(CH3)Cl2 act like the chlorides of the more positive metals.

By the acquisition of two halogen atoms the compounds of the
form AsXj pass into AsXj : —

As(CH3)3 yieWs As(CH3).Cl,
As(CH3),a « As(CH3),Cl3
As(CH3)Cl3 " As(CH3)Cl^.

Heat converts these into the compounds of the form AsXj and
alkylogens : —

AsfCHj^^Cl =As(CH3)3 +CHaCI
As(CH3)3Cl, = As(CH3),Cl + CH3CI
As(CH3)jCl3 = As(CH3)Clj, + CH3CI and
As(CH3)a^ =AsCl3 +CH3CI.

The readiness with which these compounds are decomposed in-
creases with the accumulation of the halogen atoms, e. g.,
As(CHg)Cl4 breaks up at 0°, while AsClj has not been obtained.

TERTIARY ARSINES AND ARSONIUM COMPOUNDS.

The tertiary arsines are formed by the action of the zinc alkyls
upon arsenic trichloride : —

2ASCI3 + 3Zn(CH3)2 = 2As(CH3)3 + sZnClj ;

and by heating the alkyl iodides with sodium arsenide \—r

AsNa3 + SC^H^I = ^&{C^^^)^ + aNal.

Cacodyl, formed simultaneously, is separated by fractional dis-
tillation.

Trimethylarsine, (CH3)3As, is a colorless liquid, insoluble in water, and
boils below 100° C. Its odor is very disagreeable.' It fumes in the air, and ab-

172 ORGANIC CHEMISTRY.

sorbs oxygen, to form the oxides, As(CH3)jO, consisting of large deliquescent
crystals. It also unites with the halogens and sulphur, forming As(CHj)3Br2 and
As(CH3)3S, soluble in water. At ordinary temperatures it combines with methyl
iodide, forming tetramethyl-arsonium iodide, As(CH3)4l, which crystallizes
from water in brilliant tables. Heat decomposes this last derivative into As(CH3)3
and CH3I. By the action of moist silver oxide tetramethyl-arsonium
hydroxide, As(CHj)4.0H, is obtained. This substance has a strongly alkaline
reaction, is deUquescent, expels ammonia from its salts, and yields crystalline salts
with the acids.

Triethylarsine, As (€2115)3, is a liquid sparingly soluble in water, and boil-
ing at 140°, with partial decomposition. It fumes in the air, but only takes
fire when heated. From its ethereal solution iodine precipitates the iodide,
As(C2H5)3l2, a yellow amorphous substance. The oxide, As(C2H5)30, is a
heavy oil, of disagreeable odor. It seems to combine to a salt with nitric acid.
The sulphide, As(C2H5)5S, is a crystalline substance, soluble in water.

Tetraethyl-arsonium Iodide, As(C2H5)4l, is produced by the union of
triethyl-arsine and ethyl iodide. It is a crystalline compound, which forms an
hydroxide, As(C2H5)4.0H, when treated with silver oxide. This is a strongly
basic, deliquescent body, yielding salts with the acids. The platinum double salt
consists of sparingly soluble, orange-red crystals.

DIMETHYLARSINE COMPOUNDS.

The monovalent group, As(CHa)2, is strongly basic (see p. 171),
and can form a series of derivatives, which, owing to their ex-
tremely disgusting odor, have been termed cacodyl compounds (from
xax6z and dSsiv) : —

Cacodyl Chloride. As(CH3)j

A"s(CH:iP" Cacodyl Oxide. ^^^cH,),

ffCHsWs Cacodyl Sulphide. As(CH3)2.CN Cacodyl Cyanide.

■*^=(CHs)2 As(CH3)jO.OH CacodylicAcid.

Cacodyl Chloride, As(CHj)2Cl, is formed by heating trimethyl arsen-
dichloride, As(CH3)3Cl2 (see above), and by acting upon cacodyl oxide with
hydrochloric acid. It is more readily obtained by heating the corrosive subli-
mate compound of the oxide with hydrochloric acid. It is a colorless liquid,
boiling at about 100°, and possessing a stupefying odor. It acts like a chloride
of the alkali metals, and yields an insoluble double salt with FtCl^. It unites
with chlorine to form the trichloride, ^(C'S.^SX~,-^\iv^ decomposes at 50°
into AsrCH3)Cl2 and CH3CI.

The bromide and iodide, As(CHj)2l, resemble the chloride, and are prepared
in an analogous way.

As(CH3)2

Cacodyl, As2(CH3)4 = | , diarsentetramethyl, is formed by heating

As(CH3)2
the chloride with zinc filings in an atmosphere of CO2. It is a colorless liquid,
insoluble m water. It boils at 170°, and solidifies at — 6°. Its odor is fright-
fully strong, and may induce vomiting. Cacodyl takes fire very readily in the
air and bums to AS2O3, carbon dioxide and water. It yields cacodyl chloride
with chlorine and the sulphide with sulphur. Nitric acid converts it into a
nitrate, As(CH3)2.0.N02.

DIMETHYLARSINE COMPOUNDS. 1 73

Cacodyl Oxide, Asrcn'v/^' *^^° termed alcarsin, is most
easily made by distilling arsenic trioxide with potassium acetate : —

4CH3.CO,K + A^Oj = ;^[c5)^/0 + 2CO3K, + 2CO,.

The distillate ignites spontaneously, because it contains some
free cacodyl ; the pure oxide does not act in this way.

Cacodyl oxide is a liquid with stupefying odor ; it boils at 150°,
and at — 25° solidifies to a scaly mass; its specific gravity at 15° is
1.462. It is insoluble in water, but dissolves very readily in alcohol
and ether. It unites with acids to form salts; these are purified
with great difficulty. The sulphate appears to have the formula : —

Slow oxidation converts the oxide into cacodyl cacodylate, which breaks up
when distilled with HjO into the oxide and cacodylic acid : —

2A^(!So)o + H^O = [As(CH3) J,0 + 2As(CH3),0.0H.

Cacodyl Sulphide, As[cH°1 /^' ^ ol'tai^ed by distilling cacodyl chloride
with b^um sulphide. It is an oily liquid insoluble in water, and inflames in the
air. Hydrochloric acid decomposes it into cacodyl chloride and HjS. Sulphur
dissolves in both it and cacodyl, forming the disulphide, [As(CH3)j]2S2, crystal-
lizing in rhombic tables, iiising at 50°.

Cacodyl Cyanide, As(CH3)2.CN, is formed by heating cacodyl chloride with
mercuric cyanide, or by the action of CNH upon cacodylic oxide. It crystallizes
in glistening prisms, which fuse at 37°, and boil at 140°.

Cacodylic Acid, (CH3)jAsO.OH (see p. 156), (dimethyl-arsinic acid), is
obtained by the action of mercuric oxide upon cacodylic oxide : —

AsfcH3)\'/° + ^"^° + ^^° = 2As(CH,),0.0H + 2Hg.

It is easily soluble in water, and crystallizes in large prisms, which melt at 200°,
with partial decomposition. Cacodylic acid is odorless, and appears to be non-
poisonous. Its solution reacts acid, and forms crystallizable salts with the metallic
oxides, e.g., (CHjj^AsO.OAg.

Hydriodic acid reduces the acid to iodide : —

As(CH3)20.0H -f 3HI = AsCCHj) J I + iVLfi + I^.

Hydrogen sulphide changes it to sulphide.

The salts of the thio-cacodylic acid, (CH3)2AsS.SH, corresponding to caco-
dylic acid, are formed by the action of salts of the heavy metals upon cacodyl
disulphide.

174 ORGANIC CHEMISTRY.

There are ethyl compounds analogous in constitution to the preceding methyl
derivatives, but they have not been well investigated.
As(C2H5)2
Ethyl Cacodyl, |. , diethylarsine, is formed together with triethyl-

arsine on heating sodium arsenide with ethyl iodidST It is an oil, boiling at
185-195°, and takes fire in the air. When its alcoholic solution is permitted to
slowly oxidize in the air, diethyl arsinic acid, (C2H5)2AsO.OH (see p. 156), is
produced; this crystallizes in deliquescent leaflets.

MONOMETHYL ARSINE COMPOUNDS.

Methylarsen-Dichloride, As(CH3)Cl2, results in the decomposition of ca-
codylic acid with hydrochloric aicid : —

As(CH3)20.0H + 3HCI = As(CH3)Cl2 + CH3CI + aH^O.

It is a heavy liquid, soluble in water, and boils at 133°. At — 10° it unites with
chlorine, forming As(CH3)Clj, which at 0° breaks up into AsCl, and CHgCl. From
the alcoholic solution hydrogen sulphide precipitates the sulphide, As(CH3)S, prys-
t^Uizing in colorless needles, melting at 1 10°.

When sodium carbonate acts upon the aqueous solution of the dichloride
methyl-arsenoxide, As(CH3)0, is formed. This is soluble, with difficulty, in
water, and crystallizes from alcohol in colorless prisms, which fiise at 95°, and
distil along with steam. The oxide is basic, and may be converted by the haloid
acids and H.S into the halogen derivatives, AsCHjX,, and the sulphide,
AsCHjS.

Silver oxide acting upon the aqueous solution of the above oxide changes it
into the silver salt of mono-methyl arsinic acid, (CH3)AsO(OH)j, an analogue of
methyl phosphinic acid (p. 156). The free acid crystallizes in large plates, reacts
acid, expels CO, from carbonates, and combines with bases to yield salts, like
(CHg)AsO(O.Ag)j. Phosphorus pentachloride converts it into As(CH3)Cl2.
When ethyl iodide acts upon sodium arsenite, AsOgNa, (p. 152), sodium mono-
ethyl arsinate, CjH5.AsO(ONa),, is produced.

ANTIMONY COMPOUNDS.

The derivatives of antimony and the alkyls are perfectly analogous to those of
arsenic ; but those containing one and two alkyl groups do not exist.

Trimethylstibine, Sb(CHg)g, antimony trimethyl, is obtained by heating
methyl iodide with an aUoy of antimony and potassium. It is a heavy liquid,
insoluble in water, fuming and also taking fire in the air. It boils at 80°. It
dissolves with difficulty in alcohol, but readily in ether. It forms compounds
similar to those of triethyl stibine with the halogens and with oxygen. Antimony
pentamethyl, Sb(CH3)5, is formed when zinc methyl is permitted to act upon
trimethyl stibine di-iodide. It is a liquid, and boils at about 100°. It does not
ignite spontaneously.

Methyl iodide and trimethyl stibine unite, and yield tetraniethylstibonium iodide,
Sb^CHjj^I, which crystallizes from water in beautiful tables. Digested with
moist silver oxide it passes into the hydroxide, Sb(CH3)^.OH, — a deliquescent,
crystalline mass with strong alkaline reaction. The hydroxide forms beautifully
crystallized salts with acids.

BORON COMPOUNDS. 1 75

Triethylstibine or Stibethyl, Sb(CjH5)j. This is perfectly analogous to the
methyl derivative. In all its reactions it manifests the character of a bivalent
metal, perhaps calcium or zinc (see p. 170). With oxygen, sulphur, and the halo-
gens, it combines energetically and decomposes the concentrated haloid acids,
expelling their hydrogen : —

Sb(C,H5), + 2HCI = Sb(C,H5),Cl, + H,.

The dichloride, Sb(C2H5)3Cl2, is a thick liquid, having an odor like that of
turpentine. The bromide solidifies at — 10° ; the iodide crystallizes in needles,
fusing at 70°. Stibethyl slovirly oxidized in the air becomes triethylstibine oxide,
Sb(C2H5)sO, an amorphous solid, soluble in water. It behaves like a di-acidic
oxide, forming basic and neutral salts, which crystallize well, c. g. : —

Sb(C2H,)3/g-Ng2 and Sb(C,H,) 3/0^02
Neutral Nitrate. Basic Nitrate.

Triethylstibine Sulphide, Sb(C2H5)jS, is formed by the union of stibethyl
and sulphur. It consists of shining crystals, melting at about 100°. It behaves
somewhat like calcium sulphide. It dissolves readily in water, precipitates sul-
phides from solutions of the heavy metals and is decomposed by acids with the
formation of hydrogen sulphide' and salts of triethylstibine oxide.

Tetraeihylstibonium Iodide, ?>h(C^^^, is obtained from ethyl iodide and
triethylstibine. It separates from water in large prisms. Silver oxide converts the
iodide into tetraethylstibonium hydroxide, 'Sii^C.^^^XiYl, a thick liquid, reacting
strongly alkaline, and yielding well crystallized salts with acids.

BORON COMPOUNDS.

Triethylborine, or Borethyl, 8(02115)3, is formed by the action of zinc ethyl
upon boric ethyl ester (p. 155) : —

2B(O.C2H5)3 + 3Zn(C2H5)2 = ^-R^C^^t + z{C^^.O\Zi^.

It is a colorless,.mobile liquid, of penetrating odor; its boiling point is 95°, and its
sp. gr. at 23° equals 0.696. It ignites in contact.with the air and bums with a
green flame. When heated together with hydrochloric acid it decomposes into
diethylborine chloride and ethane: —

B(C2H5)3 + HCl = -&{<:- fi^fX + CjH,.

Slowly oxidized in the air triethylborine passes into the diethyl ester of ethyl boric
acid or Boron Etho-diethoxide, V.{Qf^C){'^-^i^^7.: This is a liquid boiling at
125°; water decomposes it into alcohol and ethyl boric acid, CjH5.B(OH)2. The
latter is a crystalline, volatile body, which has a faintly acid reaction and is soluble
in water, alcohol and ether.

Bormethyl, trimethylborine, B(CH3)s, is a colorless gas, that may be condensed
by cold.

176 ORGANIC CHEMISTRY.

SILICON COMPOUNDS.

The nearest analogue of carbon is silicon, therefore its derivatives
with alcoholic radicals are very similar to the hydrocarbons.

Silicon-methyl, Si(CH3)4, is formed on heating SiCU with
zinc methyl: —

SiCl^ + 2Zn(CH3)2 = Si(CH3)4 + zZnCl^.

It is a mobile liquid, boiling at 30°. It is not changed by water,
boils at + 10°, and behaves like a hydrocarbon (carbon tetra-
methane, C(CHs)4).

Silicon-Ethyl, Silicon-Tetraethide, Si(C2H5)4, is similar to
the preceding, and boils at 153°. By the action of chlorine there

is formed a substitution product, Si-j V,rT/^[, boiling at 185°,

which acts exactly like a chloride of a hydrocarbon. By the action
of potassium acetate on this an acetic ester results : —

(C,H5),slc,H4.0.C,H30.
Alkalies decompose this into acetic acid and the alcohol : —

(C,H5)3Si.C,H,.OH.

This so-called silico-nonyl alcohol corresponds to nonyl alcohol,
(C2H5)3C.CH2.CH20H. It boils at 195°, and is insoluble in water.

Silicon Hexethyl, or Hexethyl-silicoethane, Si2(CjH5)j, is formed by the action
of zinc ethyl upon Si^Ig (obtained from I^Si by means of silver). It is a liquid,
boiling from 250-253°.

On heating ethyl silicate, Si(O.C2H5)4 (p. 156), with zinc ethyl and sodium, the
ethoxyl groups, (O.C^Hj), are successively replaced by ethyl groups. The product
is a mixture of mono-, di- and triethylsilicon esters and silicon tetraethide, which
are separated by fractional distillation, iv

Triethylsilicon Ethylate, (CjH5)3Si.O.Cj|H5, Is a liquid, boiling at 153°,
insoluble in water, and having a sp. gr. 0.841 at 0°. Acetyl oxide converts it into
the acetic ester, which yields triethylsilicon hydroxide, (CjHjjgSi.OH, when
saponified with potash. The latter is sometimes called triethylsilicol ; it is analo-
gous to triethyl carbinol, (CjH5)3C.OH, and deports itself like an alcohol. It is
an oily liquid, insoluble in water.

Diethylsilicon-diethylate, (C2H5)jSi.(O.CjH5),. An agreeable - smelling
liquid, insoluble in water, and boiling at 155.8°. Its sp. gr. equals 0.875 ^t 0°.

On treating it with acetyl chloride the compounds (€2115)281^™^ ^, and

(CjH5)2SiCl2, are formed. The latter is a liquid, boiling at 148°. It fumes in air,
and with water yields diethylsilicon oxide, (€2115)2310, analogous to diethyl
ketone, (CjH5)2CO.

Ethylsilicon-triethylate, (CjH5)Si(O.C2H5)3, is a liquid with a camphor like
odor, boiling at 159°, and slowly decomposed by water. Heated with acetyl

METALLO-ORGANIC COMPOUNDS. 1 77

chloride it forms ethyl silicon trichloride, (C2H5)SiCl3. This liquid fiimes strongly
in the air, boils at about 100°, and when treated with water passes into ethyl silicic
acid, (C^jHjjSiO.OH (Silico-propionic acid), which is analogous to propionic acid,
CjH5.CO.OH, in constitution. It is a white, amorphous powder, that becomes
incandescent when heated in the air. It dissolves in potassium and sodium hydrox-
ides to form salts.

METALLO-ORGANIC COMPOUNDS.

The metallo-organic compounds are those resulting from the
union of metals with monovalent alkyls ; those with the bivalent
alkylens have not yet been prepared. Inasmuch as we have no
marked line of difference between metals and non-metals, the
metallo-organic derivatives attach themselves, on the one side, by
the derivatives of antimony and arsenic, to the phosphorus and
nitrogen bases ; and on the other, through the selenium compounds,
to the sulphur alkyls and ethers. The tin derivatives approach the
silicon alkyls and the hydrocarbons.

Upon examining the metals as they arrange themselves in the periodic system
it is rather remarkable to find that it is only those which attach themselves to the
electro-negative non-metals that are capable of yielding alkyl derivatives. In the
three large periods this power manifests and extends itself only as far as the group
of zinc (Zn, Cd, Hg). (Compare Inorganic Chemistry.) The alkyl derivatives
of potassium and sodium, which cannot be isolated and are non-volatile, appear to
possess a constitution analogous to that of the hydrogen compounds, NajH and
KjH, or sodium acetylene, C,HNa.

Those compounds in which the metals present their maximum
valence, e.g.,

II III IV IV v

Hg(CH3), AKCH,), Sn(CH3), PbCCH,)^ SbCCH,),,

are volatile liquids, usually distilling undecomposed in vapor form ;
therefore, the determination of their vapor density is an accurate
means of establishing their molecular weight, and the Valence of the
metals. Being saturated compounds, they are incapable of taking
up additional affinities.

The behavior of the metallo-organic radicals, derived from the molecules by
the separation of single alkyls, is especially noteworthy. The monovalent radi-
cals, e. g.,

II III IV IV V

Hg(CH,)- Tl(CH3)j- Sn(CH3)3- Pb(CH3)3- Sb(CH3),-,

show great resemblance to the alkali metals in all their derivatives. Like other
monovalent radicals they cannot be isolated. They yield hydroxides, d. g.,

HgCCjH5).OH T1(CH3),.0H Sn(CH3)3.0H,

perfectly similar to KOH and NaOH. Some of the monovalent radicals, when

IS

T78 ORGANIC CHEMISTRY.

separated from their compounds, double themselves (derivatives of metals of the
silicon group) : —

SiCCH,), Sn(CH3), Pb(CH,),

Si(CH3)3 Sn(CH,)3 PKCH,);

By the exit of two alkyls from the saturated compounds, the bivalent radicals
result : —

III IV IV V

=Bi(CH,) =Te(CH3), =Sn{C,n,), =Sb(CH3)3.

In their compounds (oxides and salts) these resemble the bivalent alkaline earth
metals, or the metals of the zinc group. A few of them occur in free condition.
As unsaturated molecules, however, they are highly inclined to saturate two aiKni-
ties directly. Antimony triethyl, Sb(CjH5)3 (see p. 175), and apparently, too,
tellurium .diethyl, Te(C2H5)2, have the power of uniting with acids to form salts;
hydrogen is liberated at the same time. This would indicate a distinct metallic
character. v

' Finally, the trivalent radicals, like As(CH3)2, can also figure as monovalent.
This is the case, too, with vinyl, CjH,. These may be compared to aluminium,
and the so-called cacodylic acid, As(CH3)jO.OH (p. 173), to aluminium meta*
hydrate, AIO.OH.

We conclude, therefore, that the electro-negative metals, by the successive
union of alcohol radicals, always acquire a more strongly impressed basic, alkaline
character. This also finds expression with the non-metals (sulphur, phosphorus,
arsenic, etc.). (Compare pp. 145 and 170.) All the reactions of the alkyl com-
pounds indicate that the various properties of the elementary atoms may be ex-^
plained by the supposition of yet simpler primordial substances. (See Inorganic
Chemistry'.)

Most of the metallo-organic compounds can be prepared by the
direct action of the metals, or their sodium amalgams,- upon the
bromides and iodides of the alkyls : —

ZnNaj + .2C2H3I = Zn/^a^s + 2NaI.

Derivatives of the electro-negative metals can also be formed from
the metallic chlorides by the action of zinc and mercury alkyls : —

SnCU + 2Zn(CH,)j = Sn(CH3)^ + 2ZnClj.

COMPOUNDS OF THE ALKALI METALS.

When sodium or potassium is added to zinc methide or ethide,
zinc separates at the ordinary temperature, and from the solution
that is thus produced, crystalline compounds deposit on cooling.
The liquid retains a great deal of unaltered zinc alkyl, but it also
appears to contain the sodium and potassium compounds — at least
it sometimes reacts quite differently from the zinc alkyls. Thus, it
absorbs carbon dioxide, forming salts of the fatty acids: —

C^HjNa + CO2 = C,H5.C0,Na.

Sodium Propionate.

COMPOUNDS OF THE METALS OF THE MAGNESIUM GROUP. 1 79

The ketones are produced by the action of carbon monoxide.
1 hese supposed alkali derivatives (p. 1 77) cannot be isolated, because
when heat is applied to them, potassium and sodium separate and
decomposition ensues. Their solutions are energetically oxidized
when exposed to the air. Water decomposes them with extreme

violpnrp

COMPOUNDS OF THE METALS OF THE MAGNESIUM GROUP.

I. BeiylUuin Ethide, Be(C2H5)„ is formed by heating beryllium with mer-
cury ethyl. It IS a colorless liquid, boiling from l8s°-i88°. It fumes strongly in
the air and Ignites spontaneously. Water decomposes it with violence, beryllium
hydroxide, Be(OH)j, separating. Beryllium Propyl, Be(CsH,)2, boils about

,/'-,***S"«S'"™ Etl^i'le. MgCCjHs)^. On warming magnesium filings with
ethyl iodide sway from contact with the air, magnesium ethyl iodide first results :—

Mg + C.H^I = Ug(^^^'-

on applying heat to this it decomposes according to the ibllowing equation :

2Mg(C,H,)I = MgCC.HJ, -f Mgl,.

Magnesium ethide is a liquid that takes fire on exposure to the ajr, and is decom-
posed by water with the production of ethane :^-

Mg(CaH J, -f- H,0 = 2C,Hj + MgO.

3. Zt'fic compounds.

The reaction observed above with magnesium may occur here,
/. e., when zinc filings act upon iodides of the alcohol radicals in
sunlight, iodides are formed, which are decomposed by heat: —

zZn/j^^Hs ^ Zn(C,H,), + Znl^.

The dialkyl derivatives may be obtained by heating a solution
of the alkyl iodides, in absolute ether, with granulated zinc or zinc
turnings, in closed vessels, to ioo°-2oo° (Frankland).

The reaction occurs at a lower temperature if an alloy of zinc and sodium be
employed as a substitute for the metallic zinc. The operation is as follows : in a
flask provided with a doubly perforated caoutchouc cork, bearing an inverted con-
denser, there is introduced a mixture of the alkyl iodide with ether and zinc-
sodium. The air is expelled from the vessel by a current of carbon dioxide, and
the heat of a water bath is then applied to it. When the reaction is complete, the
condenser is reversed, and the zinc compound distilled off in a current of COj.

Pure zinc turnings may replace the zinc-sodium if they have been previously
attacked by sulphuric acid, and the pressure of the apparatus increased. This
may be accomplished by connecting the inner tube of the condenser with another
tube extending into mercury. The most convenient method of preparing zinc
ethide is to let ethyl iodide act upon zinc-copper. (Berickie, 6, 200.)

l8o ORGANIC CHEMISTRY.

The zinc alkyls, are colorless liquids, fuming strongly in the air
and igniting readily ; therefore, they can only be handled in an
atmosphere of carbon dioxide. They inflict painful wounds when
brought in contact with the skin. Water decomposes them very
energetically, forming hydrocarbons and zinc hydroxide : —

ZnCCH,)^ + 2HjO = 2CH4 + Zn(OH)j.

Oxygen is added by slow oxidation in tlie air and compounds, e. g., (CH3)2Zn02,

analogous to peroxides, are produced: — Zn^p^jj' +O2 ^ Zn^^'p^jj^

These explode readily and liberate iodine from potassium iodide (Berichte, 23, 396).
The alcohols convert the zinc alkyls into zinc alcoholates and hydrocarbons : —

Zn(C,H,), + C,H5.0H = Zn/°^^2H5 ^C,He.

The free halogens decompose both the zjnc alkyls and those of Qther metals very
energetically : —

ZnCCjHs)^ + 2Brj = 2C,H5Br+ ZnEr^.

Zinc Methide, Zn(CHj)2, is a disagreeably smelling, njobfle liqui4, which bpils
at 46°. Its sp. gr. at lo" is 1.386.

Zinc Ethide, Zn(CjH5)2, boils ^t 118°, and ha? the sp. gr. 1.182 at 18'.
With alcohol it yields zinc alcoholate and ethane :—

Zn(C,H5), + 2C,H5.0H = Zn(O.C7H,), + 2C,H,.

Sulphur dissolves in it, forming zinc merc^ptide, Zn(S.C2H5)2.
Zinc Isoamyl, Zn(CjHi^)2, boils at 220°, fumes strongly in the air, but does
not ignite spontaneously.

The zinc alkyls are very reactive, hence, serve for the prepara-
tion of many other compounds. Thus, they readily react with
chlorides of the heavy metals and the metalloids, whereby alkyl
derivatives of the latter are produced (p. 178). The hydrocarbons
(see p. 71) are produced when they are heated to 150° with alkyl
iodides : —

ZnCC^H,)^ + 2C,H5l = 2C2H5.C3H, + Znl,,
Ethyl-allyl. '

Carbon oxychloride converts them into ketones ! —
COCI2 + Zn{CH3)3 = C0/^g=

The ketones are also produced in the action of the zinc alkyls
upon the chlorides of the acid radicals in the cold : —

2CH3.CO.CI + Zn(C2H5)2 = 2C0/^'^j| + ZnClj.
Acetyl Chloride. Methyl-ethyl Ketone.

When an excess of the zinc alkyl is employed, tertiary alcohols are
formed (p. 120).

COMPOUNDS OF THK METALS OF THE MAGNESIUM GROUP. l8l

The zinc alkyls unite with the aldehydes and ketones to form
compounds, which are decomposed by water into higher secondary
and tertiary alcohols (p. 120). The alkyl oxides and the alkylen
oxides are not affected by the zinc alkyls (JBerichte, 17, 1968).

The zinc alkyls absorb sulphur dioxide and become zinc salts of the sulphinic
acids (p. 154). Nitric oxide dissolves in zinc diethyl and forms a crystalline com-
pound, from which the zinc salts of the so-called dinitroethylic acid, C2H5.
NjOjH, is obtained by the action of water and COj.

4. Mercury Compounds.

These are formed according to methpds similar to those em-
ployed for the zinc compounds. The alkyl iodides unite with
mercury at ordinary teniperatyres to yield iodides (sunlight is
favorable) :t—

Hg + C,H,I = Hg/^^,H,

The dialkyl compounds are produced when sodium amalgam acts
upon the alkyl iodides : —

HgNa^ -f 2C,H,I = Pg$(c'H' + ^^al.

The reaction may be executed as follows : Liquid sodium amalgam is gradually
added to the mixture of the iodide or bromide with ylj volume ethyl acetate,
accompanied by Irequent shaking of the vessel ; the reaction occurs then with
increase of heat. When the mass becomes syrupy, it is distilled, and the opera-
tion repeated until all the iodide is decomposed (until on boiling with HNO3,
iodine no longer separates). The oily distillate is shaken W>th potassium hydroxide
to decompose the ethyl acetate, the heavy oily mercury alkyl separated, and after
drying with calcium chloride it is distilled. (Annalen, 103, 105, and log,)

The action of zinc alkyls upon mercuric chloride also produces
them ;— r

HgCI, -f (CjH,),Zn = HgCC.Hs), + ZnCl,.

These compounds qre colorless, heavy liquids, possessing a faint,
peculiar odor. Their vapors are extremely poisonous. Water and
air occasion no change in them, but when heated they ignite easily.

The haloid acids cause one alkyl group to split off, leaving salts
of the monoalkyl derivatives i^—

Hg<§H' + HC1 = Hg/^f ^» + C,H„

and when moist silver oxide acts on the halogen derivatives,
hydroxyl com'^oyyc^A^ are produced : —

Hg(C2H5)Cl -f AgOH = Hg(C,H5).0H -f AgCl;
these are strongly alkaline, and form crystalline salts with the acids.

iSz ORGANIC CHEMISTRY.

One and two alkyls separate from the mercury alkyls by the
action of the halogens : —

HgCC.H,), + I, = Hg(C,H5)I + C,H,I and
Hg(C,H,5l M- I, = Hgl, + C,H,I.

Mercury-Methyl, Hg(CH3)2, is a liquid having a specific gravity of 3.069;
it boils at 95°, and is but slightly soluble in water. When a molecule of iodine
is added to its alcoholic solution there is formed mercury methyl iodide,
Hg(CH3)I, insoluble in water, but soluble in alcohol, from which it crystallizes
in shining leaflets, fusing at 143°. Potassium cyanide converts the iodide again
into mercury-methyl. When treated with silver nitrate the salt, Hg(CH,).O.NOj,
is produced.

Mercury Ethide, Hg(C2H5)2, has a specific gravity of 2.44, and boils at
159°. At 200° it decomposes into Hg and C4Hi„. Its cAl/>riiie,Ilg{C2tli)Cl,
separates in brilliant needles, when its alcoholic solution is digested with HgClj.
Direct sunlight decomposes the iodide into Hg and C^Hjg. These halogen
derivatives when treated with moist silver oyiiAe,y\e\A mercury ethyl hydroxide,
Hg(C2H5).OH, a thick liquid of strong alkaline reaction, and soluble in both
water and alcohol. It forms crystalline salts with the acids.

Mercury-Allyl Iodide, Hg(C,H5)I, is obtained when allyl iodide is shaken
with mercury. It crystallizes from alcohol in shining leaflets, fusing at 135°.
Propylene results when hydriodic acid acts on the iodide : —

Hg(C,H,)I + HI =^ Hgl, + C,H,.

COMPOUNDS OF THE METALS OF THE ALUMINIUM GROUP.

The aluminium alkyl derivatives attach themselves to those springing from
boron (p. 175); however, it appears that only those exist in which three alkyls
are present. They are produced by the action of the mercury alkyls upon
aluminium filings: —

2AI + 3Hg(CH,)2 = 2A1(CH,)3 + 3Hg.

Aluminium-Methyl, A1{CH3)3, boils at 130°, and crystallizes at 0°. It
fumes in the an:, and is spontaneously inflammable. Water decomposes it with
great yiolence, forming ethane and aluminium hydroxide. Its vapor density, has
been found to be 2.8 (or 35.6, H ^ 1) at 240° ; this would answer to the mole-
cular formula A^CH,), = 72.3. It, however, appears that at low temperatures
the molecules Al2(CH3)3 also exist (see Berichte, 22, 551).

Aluminium-Ethyl, AirCgHj),, is perfectly analogous to the preceding com-
pound, but does not solidify in the cold. It boils at 194°. At 240° its vapor
density has been found equal to 4.5 (or 64, H = 1), almost corresponding to the
molecular formula A1(C2H5)3 = H4.3.

The derivatives of trivalent gallium and indium have not been prepared.

The thallium-diethyl compounds, TlfC^HjjjX, are known.

Thallium-Diethyl Chloride, T^CjHJjCI, is formed when zinc ethide is
allowed to act upon thallium chloride : —

TICI3 -I- Zn(C2H5)2 = T1(C2H3)2C1 + ZnCl^.

Thallium-diethyl salts, e.^., T1(C2H5)20.N02, are obtained from this by double
decomposition with silver salts. . If the sulphate be decomposed with barium

COMPOUNDS OF THE METALS OF THE GERMANIUM GROUP. 1 83

\y Ax Ac,tkallium-diethyl hydroxide, tiif^^^^.OH, is obtained. This is readily
soluble in water, crystallizes therefrom in glistening needles, and has a strong
alkaline reaction.

COMPOUNDS OF THE METALS OF THE GERMANIUM GROUP.

The alkyl derivatives of the tetravalent metals, germanium (7'2.3),
tin (117) and lead (206), are perfectly analogous in constitution to
those of silicon (p. 176) belonging to the same group; the dif-
ferences in reaction of the tin and lead compounds are induced by
the more positive, metallic nature of tin and lead (see p. 178).
The compounds of germanium form the transition to those of sil-
icon and tin.

1. Germanium-Kthide, Ge(C2H5)4, is formed when zinc ethide acts upon
germanium chloride. It is a liquid with a leek-like odor. It boils at 160°, and
its sp. gr. is 0.96. At Ordinary telnperatures it is not altered on exposure to the
air.

2. Tin Compounds. — In addition to the saturated derivatives
with four alkyls, tin is also capable of uniting with three and two
alkyls to groups which act like basic radicals, forming salt-like com-
pounds with negative groups : —

Sn(C2H5)4 Tin tetraethyl
Sn(C2H5)3Cl Tin triethyl chloride
Sn(C2H5)aCl2 Tin diethyl chloride.

Tin diethyl, Sn(C2H5)2, appears to exist as an unsaturated mole-
cule (like tin dichloride, SnClj), while the group, Sn(C2H5)3, in
free condition doubles itself: —

Sn(C2H5)s

Sn2(C2H5)6 = | -Di-t}ntriethyl.^

Sn(C,Hj3

Tin Tetraethyl, Stannic Ethi4e, Sn(CjH5)i, is best pre-
pared by distilling tin chloride with zinc ethyl; —

Sna^ + aZnCCaHs)^ = SnCC^H,)^ + aZnCl^.

It is a colorless, ethereal smelling liquid, boiling at 181° and pos-
sessing a specific gravity of 1.187 at 23°. Its vapor density equals
8.02 or 116 (H = i). It is insoluble in water and does not suffer
change on exposure to the air. By the action of the halogens the
alkyls are successively eliminated ;-^

Sn C h'JJi + I. = Sn(C2H,),l2 + C^ H I
SnCC^Hj) Ja + I2 =T Snl4 + zC^HJ.

Hydrochloric acid acts similarly : —

SnCCjHJ^ 4- HCl = Sn(C2H5)3Cl + 2C2He, etc.

184 ORGANIC CHEMISTRY.

Tin Tetramethyl, SnCCHa)^, is similar to the preceding, boils
at 78°, and has a specific gravity at 0° of 1.314.

On heating an alloy of tin and a little sodium (about 2 per cent.) with ethyl
iodide, there results a mixture consisting of Sn(C2H5)3l and Sn(C2H5)2l2,
which may be separated by fractionation. With an alloy rich in sodium (about
20 per cent.) the products are 80(02115)2 and 802(02115)5 ; the latter is almost
insoluble in alcohol, while the first is very soluble and can be re-precipitated by
water.

Tin-Triethyl Iodide, Sn(C2H5)3l, is a colorless oil, insoluble in water and
having a disagreeable smell. It boils at 231°, and has a specific gravity of 1.833
at 22°. Hydrochloric acid precipitates the chloride, Sn(C2H5)3Cl, from tin
triethyl salts, as a heavy oil, which solidifies at 0°. It boils from 208-210°, and
has a specific gravity of 1.428. Alcohol is a solvent for both. When either one
is acted upon by silver oxide or caustic potash, there is produced : —

Tin-Triethyl Hydroxide, Sn(C2H5)3.0H, crystallizing in shining prisms,
melting at 66°, and boiling undecomposed at 272°. It volatilizes along with the
steam. It is sparingly soluble in water, but dissolves readily in alcohol and ether.
It reacts strongly alkaline, absorbs carbon dioxide, and yields crystalline salts with
the acids, e. g,, Sn(C2H5)j.O.N02. When the hydroxide is heated for some
time to almost the boiling temperature, it breaks up into water and tin-triethyl

oxide, On/r'^jj'x' /0> ^° °'^y liquid, which in the presence of water at once

r^enerates the hydrate.

Sn(C2H5),
Free Tin-Triethyl, | = Sn2(C2H5)5, or Stannoso-stannic Ethide,

Sn(C2H5),
IS produced, as already described, by heating tin-sodium with ethyl iodide; also
on warming tin-triethyl iodide with sodium : —

2Sn(C2H5)3l + Na2 = Sn2(C2H5)5 + 2NaI.

It is a liquid, of mustard-like odor, insoluble in alcohol, but readily soluble in
ether. It distils with slight decomposition at 265-270*^. It combines with

oxygen, forming tin-triethyl oxide, „ /r'^H^v yOi ^°^ w't** iodine yields tin-
triethyl iodide :— aiH^-a^sh/.

Sn(C2H5)3

I -f l2 = 28n(C2H5)3l.

Sn(C2H5)3

Tin- Diethyl, or Stannous Ethide, 80(02115)2. Its preparation is described
above. It is a thick oil, decomposed when distilled, therefore its molecular
weight has not been determined. It combines with oxygen and the halogens : —

Sn(C2H5)2 + l2 = Sn(C2H5)2l2.

When distilled it decomposes completely into tin and tintetraethyl: —

28o(C2H5)2 = Sn(C2H5)^ + Sn.

Tin-Diethyl Chloride, Sn(C2H5)2Cl2, is best prepared by dissolving tin-diethyl-
oxide in hydrochloric acid. It is insoluble in water, alcohol and ether, crystal-
lizes in needles, fusing at 60° and boils at 220°. The iodide, Sn(C2H5)jl2, is

COMPOUNDS OF BISMUTH. 1 85

also produced by the action of ethyl iodide in sunlight upon zinc filings. It crys-
tallizes in needles, fuses at 44.5°, and boils at 245°.

Ammonium hydroxide and the alkalies precipitate from aqueous solutions of
both the halogen compounds: —

Tin-Diethyl Oxide, Sn(C2Hj20, a white, insoluble powder. It is soluble in ex-
cess of alkali, and forms crystalline salts with the acids, ^. p-., SnfC,H = ') ^S"™*

3. LEAD COMPOUNDS.

These are very similar to the preceding ; derivatives with two alkyls do not,
however, exist : —

Pb(C2H5)^ Lead tetraethyl.
Pb(C2H5)3Cl Lead triethyl chloride.
V\{C^^\ Di-leadtriethyl.

Lead- Tetraethyl, Pb(C2H5)^, is obtained by heating lead chloride with zinc
ethide : —

2PbCl2 -f iLD.{Q.^^\ = PbCCjHj)^ -f. aZnClj + Pb.

It is an oily liquid, distilling out of air contact at about 200°, with partial decom-
position. When heated in the air it takes fire and burns with an orange-colored
flame. When hydrogen chloride acts upon it, ethane is evolved and Lead Tri-
ethyl chloride, Pb(C2H5)3Cl, formed, which crystallizes in silky, shining needles.
The iodide, Pb( 02115)31, is very similar to the last, and is produced when iodme
acts upon lead-tetraethyl. On heating either of these derivatives with silver oxide
or caustic potash, Uadtriethyl hydroxide, Pb(C2H5)3.0H, distils over. This
reacts very alkaline, and forms crystalline salts with the acids. The sulphate,
[Pb(C2H5)3]2S04, dissolves in water with difficulty.

Lead- Triethyl, Pb.^(C2H5)5, is obtained by the action of ethyl iodide on an
alloy of lead and sodium : —

2PbNa3 -f eC^H^I = PbjfC^Hs)^ -f 6NaI.

Lead triethyl is a yellowish liquid, insoluble in water, possessing a sp. gr. of
1.471 at 10°, and boiling with partial decomposition. It reacts energetically with
the halogens : —

• Pb,(C,H5)5-|-I, = 2Pb(qH5)3l.

The lead-methyl derivatives are perfectly analogous to the ethyl compounds.

Consult Berichte, 22, 467, for the experiments made with the view of preparing
Titanium-Tetraethyl, Ti(CjH5)4.

COMPOUNDS OF BISMUTH.

These arrange themselves with those derived from antimony and arsenic ; but
in accordance with the complete metallic nature of bismuth, we do not meet any
compounds here analogous to stibonium (p. 171) or arsoniura.

Bismuth- Trimethyl, Bi(CH3)3, results from the interaction of zinc ethide and
bismuth tribromide. It is a mobile, strongly refracting liquid, with a disagreeable
odor. Its sp. gr. is 2.3 at i8°. It fumes in the air, and oxidizes rapidly. It ex-
plodes if heated in air. Surrounded by an indifferent gas it boils at 110° without
decomposition (Berichte, 20, 1516; 21, 2035).

Bismuth-Triethyl, ^\(C^^^, is formed by acting upon an alloy of bismuth
and potassium with ethyl iodide. It is perfectly similar to the methide, and in-
16

1 86 ORGANIC CHEMISTRY.

flames rapidly on exposure to the air. It explodes if heated to 150°. It distils
without decomposition under reduced pressure (below 7.9 mm. at 107°). It
reacts very energetically with the halogens, according to the equation : —

BilC^Hj), + 2I, = Bi(CjHj)I, + 2C,H5l.

Bismuth-ethyl Chloride, Bi(CjH5)Cl2, is formed when mercuric chloride acts
on bismuth-triethyl : —

Bi(C,H,)3 + aHgC), = Bi(C,H5)Cl, + 2Hg(C,H5)Cl.

The iodide, Bi(C2H5)Ij, results when the chloride is warmed with KI. This
salt crystallizes in yellow leaflets. From its alcoholic solution the alkalies pre-
cipitate Bismuth-ethyl oxide, Bi(C2H5)0, an amorphous, yellow powder, which

takes fire readily in the air. The mtrate,'Ei{C^^^r)-Kr\' ^ produced by
adding silver nitrate to the iodide. This crystallizes from alcohol, explodes on
being warmed, and is decomposed by water with formation of bismuth dinitrate,
Bi{OH)(N03),.

ALDEHYDES AND KETONES.

Aldehydes and ketones contain the carbonyl group CO, which in
the latter unites two alkyls, but in the former is combined with
only one alkyl and one hydrogen atom : —

AldehydS Dimethyl Ketone.

This expresses the similarity and the difference in character of
aldehydes and ketones.

The methods of preparation common to both classes of com-
pounds are : —

I . Oxidation of the alcohols,' whereby ■ the primary alcohols
change to aldehydes and the secondary to ketones (see p. 118) : —

CH3 CH.

I +0=1
CHj.OH iHO

Ethyl Alcohol. Aldehyde.

+ H,0

ch:>h.oh + o = ^|^ha

Isopropyl Alcohol. Dimethyl Ketone.

The above oxidation may be effected by oxygen ; or air in presence of platinum
sponge, or by ozone. It takes place more readily on warming the alcohols with
potassium dichromate (or MnO^) and dilute sulphuric acid. To prevent the oxid-
ation extending too far, it is sometimes recommended to employ an aqueous
solution of chromic acid (Berichte, 5, 699).

ALDEHYDES. 1 87

Conversely, aldehydes and ketones again become primary and
secondary alcohols by an addition of hydrogen : —

CHj.CHO + H2 = CH3.CHj.OH

Aldehyde. Ethyl Alcohol.

ch:>co+h,= ^H3\^,jjojj

Acetone. Isopropyl Alcohol.

Further oxidatipn converts the aldehydes into acids, but the ketones
suflfer decomposition by means of it : —

CH..CHO + O = CH3.CO.OH.

Aldehyde. Acetic Acid.

Empirically, the aldehydes are distinguished from the alcohols by
possessing two atoms less of hydrogen — hence their name (from
Alkohol dehydrogenatus), e. g., ethyl aldehyde, propyl aldehyde,
etc., etc. On account of their intimate relationship to the acids,
their names are also derived from the latter, like acetaldehyde,
propionic aldehyde, etc.

2. The dry distillation of a mixture of the calcium, or better,
barium salts of two monobasic fatty acids. Should in this case one
of the acids be formic acid, aldehydes are produced : —

CH3.CO.OM' + HCO.OM' = CH3.COH + COjMe'j
An Acetate. Formate. Acetaldehyde.

In all other instances ketones result, and they are either simple,
with two similar alkyls, or mixed, with two dissimilar alkyls : —

CH3.CO.OM' + CH3CO.OM' = chO^° + C^sMe/

An Acetate. An Acetate. Dimethyl Ketone.

CH3.CO.OM' f C2H5.CO.OM' = (^h'/CO + CO3M/
An Acetate. A Propionate. Methyl-ethyl Ketone.

When working with higher aldehydes, which volatilize with dif-
ficulty, and ketones, it is advisable to distil in vacuo.

Both aldehydes and ketones combine with primary alkaline sul-
phites, yielding crystalline compounds (see later).

ALDEHYDES.

The aldehydes, e. g., acetaldehyde, CH3.CHO, are compounds
containing the group COH, which is readily formed by the oxida-
tion of the primary alcoholic group, CH^.OH (p. 117)- Again,
in accordance with their fatty acid origin, aldehydes may be
viewed as the hydrogen derivatives of the acid radicals. This would

l88 ORGANIC CHEMISTRY.

explain their formation by the action of nascent hydrogen (sodium
amalgam) upon the chlorides of acid radicals, or their oxides (the
acid anhydrides) : —

CH..C0C1 + Hj = CH,.COH + HCl,
Acetyl Chloride. Acetaldehyde. -

CH CO/° + ^"» = 2CH3.COH + Hp.
Acetic Anhydride. Acetaldehyde.

Hence, they may be regarded as the oxides of bivalent radicals
(like CH3. CH = ethidene), or as the anhydrides of the very un-
stable dihydroxyl derivatives of these. Wherever the formation of
these latter compounds occurs we can expect, from their close anal-
ogy to the glycols, that water will split off and the aldehydes
result : —

CH3.Ch/°^ = CH3.CHO + HjO.

This explains the formation of e. g., acetaldehyde (ethidene oxide) from
ethidene chloride, CHjCHClj, when heated with water (more readily in presence
of lead oxide), and also its production from the ethereal and ester-like compounds,
such as ethidene diacetate, CH3.CH(O.C2H30)2, by saponification with alkalies or
sulphuric acid. In a similar manner, on heating glycollic and lactic acids,

CH.j(^P^ „,CH3.CHQ p„ TT, with acids, there occurs a splitting-off of formic

acid (or of CO and HjO) and the products are methylene oxide, CHjO (formic
aldehyde), acetaldehyde, CH3.CHO, etc.

Besides these general methods the aldehydes, as the transitional
members to the acids, frequently appear in the oxidation (by means
of manganese peroxide and dilute sulphuric acid, or a chromic acid
solution) of complex substances such as the albuminoids.

The aldehydes exhibit in their properties a gradation similar to
that of the alcohols. The lower members are volatile liquids,
soluble in water, and have" a peculiar odor, but the higher are
solids, insoluble in water, and cannot be distilled without decom-
position. In general they are more volatile and dissolve with more
difficulty in water than the alcohols. In chemical respects the alde-
hydes are neutral substances, yet they are easily oxidized to acids
on exposure to the air : —

CHs.CHO,+ O = CHj.CO.OH.

Their ready oxidation by the oxides and salts of the noble metals
(the latter being separated in free condition) is characteristic of
aldehydes. On adding an aqueous aldehyde solution to a weak
ammoniacal silver nitrate solution, silver separates on the sides of
the vessel as a brilliant mirror.

ALDEHYDES. 1 89

The reaction is more delicate in the presence of caustic potash [Berickte, 15,
1635 and 1828) ; such a solution will even reduce cane sugar and glycerol when
assisted by heat. Alkaline copper solutions are reduced, too, by many fatty alde-
hydes {jBerichte, 14, 675 and 1950). The reduction of alkaline silver and copper
solutions is, however, not peculiar to the aldehyde groups alone, but belongs also
to some other atomic groups (see acetone alcohol, glycid alcohol, hydrazine). A
very delicate reaction of the aldehydes is their power of imparting an intense
violet color to a fuchsine solution previously decolorized by sulphurous acid
(jBerichte, 14, 1848). Chloral hydrate and the glucoses do not, but some ketones
do, show this reaction (jBerichte, 14, 79l)- The following is more sensitive : Add
an aldehyde and a little sodium amalgam to the sodium hydroxide solution of diazo-
benzene sulphonic acid and a violet-red coloration is produced. Grape sugar and
other sugars, but not chloral, will do the same. Acetone and acetic ether produce-^
a dark red coloration {Berickte, 16, 657, and 17, Ref. 385). "^

When oxygen or air is conducted through the hot solution of an aldehyde (like
paraldehyde) in alcoholic potash, an intense light-display is observed; many
aldehyde derivatives, and even grape sugar, deport themselves similarly {Berickte,
10, 321).

Nearly all the aldehydes are converted into resin by the alkalies ;
some are transformed into acids and alcohols by alcoholic alkali
solutions : —

2C^Hg.COH + KOH = CiH9.CO.OK + C^Hg.CHj.OH.

Amyl Aldehyde. Pot. Valerate. Amyl Alcohol.

Phosphorus pentachloride replaces the oxygen of aldehyde by
two chlorine atoms (p. 92) : —

CH j.CHO + PCI5 = CH3.CHCI2 + PCI3O.

Notwithstanding they are really saturated compounds, aldehydes
possess, in a remarkable degree, the property of uniting two affini-
ties directly, and thereby changing the oxygen united with. two
affinities to the hydroxyl group : —

, CH3.CHO + HX = CH3.Ch/qjj

Thus they become alcohols by the addition of two hydrogen atoms.
They unite directly with ammonia to form crystalline compounds,
called aldehyde-ammonias : —

CH3.CHO -I- NH3 = CHj.CH/gg".

These are readily soluble in water but not in ether, hence am-
monia gas will precinitate them in crystalline form from the ethereal
solution of the/ aldehyi^es. They are father unstable and dilute
acids again resflfve them'into their components. Aldehydes unite
in a similar manner with acid alkaline sulphites, forming crystalline
compounds : —

CH3.CHO -1- SOjHNa = CH3.Ch/°^^j^^,

19° ORGANIC CHEMISTRY.

which may be regarded as salts of oxysulphonic acids. The alde-
hydes may be released from these salts by distillation with dilute
sulphuric acid or soda. This procedure permits of the separation
and purification of aldehydes from other substances.

Aldehydes also combine with hydrogen cyanide, yielding oycy-
ryawzV/w or cyanhydrins : —

CH3.CHO + CNH = CH3.CH (^

from which oxyacids are prepared.

These cyanides are often crystalline and may be prepared by prolonged heating
of the aldehydes with a concentrated CNH solution, or by adding hydrochloric
acid to a mixture of the aldehyde and pulverized potassium cyanide (BerichU, 14,
23S and 1965). When these compounds are distilled they usually break up into
their components. The alkalies also cause a separation of CNH. When hydro-
chloric or sulphuric acid acts upon them they pass into oxyacids.

With ammonium cyanide aldehydes form ainiddcyanides, like

CH3.CH ^ pvr") which yield amido-acids (see these).

Being the oxides of the radicals, R.CH= (p. 188), aldehydes
can, by direct additions, form ether and ester derivatives. Thus
they combine at 100° with the alcohols and build the so-called
acetals : —

CH3.CHO + aC.Hj.OH = CH3.Ch/°;^^H5 ^ h,0;

Ethidene-diethyl Ether.

and with the acid anhydrides they yield esters: —

CH CHO'-L ^2"3C*\(-) ftr ctj/O-CjHjO

eH.3.i.tiu -i- c^nf)/^ — ^"3-'""\o.CjH,o.

Ethidene Diacetate.

These compounds will be treated with the derivatives of the bivaleat
radicals.

The polymerization of the aldehydes depends upon a similar par-
tial separation of the oxygen atoms and the union through the latter
of several aldehyde radicals, CHs.CH^. This occurs especially
with the lower members of the series. Thus from formic aldehyde,
CH2O, arises trioxymethylene, (CH20)3, from acetaldehyde, CjHiO,
paraldehyde, (C2H40)3, and metaldehyde, (CjH40)n (see p. 194).

The readiness with which the polymerides break up into simple molecules
shows that in them the carbon atoms are not in union with each other; their
power of refracting light (p. 60) would also indicate this {Annalen, 203, 44).

Finally, the aldehydes condense readily, /. e., two molecules
unite by means of two carbon atoms, and water may or may not
separate (aldehyde and aldol condensation see p. 194).

ALDEHYDES OF THE PARAFFIN SERIES. I9I

By such an exit of water the aldehydes (also the ketones) are en-
dowed with the power of entering into combination with free
hydroxylamine (or its HCl-salt), and forming the so-called aldox-
imes facetoximes) (V. Meyer) : —

CHj.CHO + HjN.OH = CHj.CHtN.OH +11 fi.
Acetaldehyde. Ethyl Aldoxime.

These contain the bivalent oximide group, N.OH, combined with
one carbon atom. They are isomerides of the nitroso-compounds
(see p. 106), hence also designated the isonitroso-derivatives of the
hydrocarbons. The aldoximes are, as a usual thing, liquid bodies
that boil without decomposition. Ethers are produced when the
hydrogen of their hydroxyl group is replaced by acid radicals, or by
the alkali metals (by means of sodium alcoholate) and the alkyls.
When boiled with acids they are again changed to aldehyde and
hydroxylamine. By the action of acetic anhydride or acetyl chloride
the aldoximes become nitriles, while the acetoximes are. changed
to acetyl esters {Berichte, ig, 1613, and 20, 501, 2196). Nascent
hydrogen converts them into amines (p. 160).

The aldoximes result from all compounds which, like the aldehydes, contain the
aldehyde group, CHO, e. g., the aldehyde acids (^Berichte, 15, 2783, 16, 823, and
1780).^ Paraldehyde and metaldehyde (see above) do not react with hydroxyl-
amineT All the ketones and compounds containing the group CO, peculiar to
them, yield corresponding acetoximes (see Ketones). These oximido- or isonitroso-
derivatives do not show the nitroso reaction (see p. 164).

All the aldehydes (and the ketones) react more readily with
phenyl hydrazine {Berichte, 16, 661, 17, 574) than with hydroxyl-
amine to form oily or solid condensation products — the hydra-
zones : —

CH3.CHO + H3N,. QH5 = CH3. CH: HN,. CeHs + H,0.

These serve for the characterization and recognition of the alde-
hydes. Boiling acids break up the hydrazones into their compo-
nents. Sodium amalgam decomposes them with the formation of
amines (p. 160) {Berichte, 17, 574)-

The aldehydes also unite with p-amido-dimethylaniline {Berichte, 17, 2939).
On boiling the aldehydes with an alcoholic solution of resorcinol and a trace of
hydrochloric acid insoluble compounds are produced. The ketones do not react
under these conditions {Berichte, ig, 1389). Mercaptals are formed by the union
of the mercaptans with the aldehydes (and ketones).

I. ALDEHYDES OF THE PARAFFIN SERIES, Cn H^nO.

I. Methyl Aldehyde, CH^O, called Formic Aldehyde,

or oxymethylene, is only known in aqueous solution and in gaseous
form. It arises in the oxidation of methyl alcohol, if its vapors

192 ORGANIC CHEMISTRY.

mixed with air be conducted over an ignited platinum spiral ; also
by the distillation of calcium formate and upon digesting methylal
with sulphuric acid.

It is noteworthy that formic aldehyde appears to exist in the plant
cells which contain chlorophyll {Berichte, 14, 2147).

Preparation : (l) Mix methylal or other acetals with sulphuric acid, fidd water
and distil. Aqueous formic aldehyde passes over (Berichie, 19, 1841); (2) con-
duct a mixture of air and the vapors of methyl alcohol over a plaU'num spiral
heated to redness (Hofmann). If a copper spiral be used a solution will be ob-
tained, containing 30 to 40 per cent, formic aldehyde (Journ. frk. Ck., 33, 321.
Berichte, ig, 2133; 20, 144; Annalen, 243, 335). i

The dilute solution may be concentrated by distillation. But little aldehyde is
expelled in this way. When the solution is very concentrated and itjis allowed to
evaporate over sulphuric acid at a low temperature, or in a vacuum, paraformalde-
hyde separates {^Berichte, 16, 917, and ig, 2135). To determine the quantity of
formic aldehyde present in a solution digest the latter with ammonia, when hexa-
methyleneamine (p. 193) will be formed, and the excess of ammonia can be de-
termined with sulphuric acid in the presence of litmus (^Berichte, 22, 1565, 1929).
Or the liquid can be evaporated below 50° to dryness and the residue, hexamethylene-
amine weighed [Legler, Berichte, 16, 1333).

The concentrated aqueous solution of formic acid not only con-
tains volatile CHjO, but also the hydrate CHj^^ j-.tt , i. <?., hypo-
thetical methylene glycol, and non-volatile poly hydrates, e. g.,
(CH2)jO(OH)2, corresponding to polyethylene glycols. Therefore
the determinations of the molecular weight of the solution, by the
method of Raoult, have yielded different values (^Berichte, 21, 3503;
22, 472). On complete evaporation of the solution the hydrates
condense to the solid anhydride (CHbO)^, paraformaldehyde.

Hydrogen sulphide precipitates formic aldehyde from its aqueous solution com-
pletely as trithiomethylene (see below). It unites with ammonium to hexamethy-
leneamine, (CH2)5N4 (see below). When heated with sodium hydroxide it
yields methyl alcohol and formic acid: aCH^O + H^O = CH^O + CHjOj.
The alkalies or alkaline earths in dilute solution convert formic aldehyde into
methyl enenitan and formose; these substances resemble the sugars.

Paraformaldehyde, (CH^Ojj, formerly called Trioxymethylene, is obtained
by the action of silver oxide upon methene di-iodide, or by heating methene di-
acetyl ester with water, to 100°. It is best prepared by distilling glycoUic acid
with a little concentrated sulphuric acid. It is most easily obtained by the con-
densation of formic aldehyde (see above). It is a white, indistinctly crystalline
mass. It sublimes below 100°. The sublimed compound melts at 171°. The
vapors have the formula CHjO which corresponds to their density. When cooled
they again condense to the trimolecular form. When paraformaldehyde is heated
with water to 130° it changes to the simple molecule CHjO.

When paramethaldehyde is heated with a trace of sulphuric acid to 120° in a
sealed tube it is changed into the isomeric Trioxymethylene, (CH20)3, crystal-
lizing in long needles and melting at 60°. Its vapor density corresponds to the
formula CjHgOj {Berichte, 17, Ref. 567).

When hydrogen sulphide is conducted into the aqueous solution of CH^O,

ALDEHYDES OF THE PARAFFIN SERIES. I93

condensed oxysulphydrides, with exceedingly disagreeable odor, are produced.
If these are boiled with concentrated hydrochloric acid, water splits off,

and Trithiomethylene, Trithioformaldehyde, CjHgSa = CH^J^'o'^S^Xg^
results. When pure it is perfectly inodorous, and Trimethylenetrisulphone,
CHj/gQ2'^jj2\so^ (^Berichte, 23, 60, 71), is produced when trithioform-
aldehyde is oxidized with potassium permanganate.

Another polymeric ThiomeihyUne, (CH^S),,, obtained from hexamethylene-
amine, results at 176° (Berichte, 19, 2344), and crystallizes in shining white
needles, fusing at 216°, and subliming readily. The vapor density answers to the
formula CjHgSj.

HexamethyUneamine, {C]A^^j^, is obtained by the action of ammonia on
aqueous formic aldehyde {Berichte, 19, 1842). It is readily soluble in water and
crystallizes from alcohol in shining rhombohedra. It sublimes in vacuo without
decomposition. For the molecular weight of the solution see Berichte, 21, 1570.
It is resolved into CHjO and ammonia again by distillation with sulphuric acicl.
It is a monacidic base, but does not react with litmus {Berichte, 22, 1929). It
unites with the alkyl iodides {Berichte, ig, 1842). Formic aldehyde also com-
bines with phenylhydrazine, amines and anilines (Berichte, 18, 3300). Nitrous
acid produces pecuhar nitrosamines {Berichte, 21, 2883).

2. Acetaldehyde, QH4O = CH3. CHO, is formed according
to the methods described above, but is generally prepared by the
oxidation of ethyl alcohol with potassium bichromate and dilute
sulphuric acid. Commercial aldehyde, and especially that employed
in the preparation of aniline colors, is obtained from the first run-
nings in the rectification of spirit. It is made, too, in the oxida-
tion of alcohol in running over wood charcoal. Its production
from vinylsulphuric acid, •S04H(C2H3), (from acetylene), by boil-
ing with water, is of theoretical interest. (Compare p. 134.)

Preparation. — Pour 12 parts H^O over 3 parts KjCr^O,, and then gradually add,
taking care to have the solution cooled, a mixture of 4 parts concentrated H2SO4,
and 3 parts alcohol (90 per cent.) ; the heat of a water-bath is now applied, and
the vapors that escape are condensed in a receiver. The resulting distillate,
consisting of alcohol, aldehyde and acetal, is next heated to 50°, and the escaping
aldehyde vapors conducted into ether, and this solution saturated with dry NH3,
when the aldehyde-ammonia, CjH^O.NHj, will separate in a crystalline form.
Pure aldehyde may be obtained from this by distilling it together with dilute
sulphuric acid. The aldehyde vapors are freed from moisture by conducting them
over heated calcium chloride.

Acetaldehyde is a piobile, .peculiar-smelling liquid. It boils at
20.8°, and has a sp. gr. of 0.8009 at 0°. It is miscible in all pro-
portions with water, ether and alcohol. It slowly oxidizes to
acetic acid when exposed to the air. From an ammoniacal silver
solution it immediately throws out metallic silver as a mirror-like
deposit. Nascent hydrogen transforms aldehyde into ethyl alcohol.
PCI5 and PBrs convert it into CHs.CHCIi, and CHa-CHBr^ (p. 189).

194 ORGANIC CHEMISTRY.

Ethylaldoxime, CHj.CHiN.OH, isonitrosoethane, produced by the action of
hydroxylamine upon acetaldehyde (p. 191), boils at 115°, possesses an aldehyde-
like odor, and is miscible with water, alcohol and ether.

Ethylidene-phenylhydrazone, CH3.CH:N:NH.C6H5, from aldehyde and
.phenylhydrazine, is a liquid boiling near 250°.

When an ethereal solution of aldehyde is saturated with dry ammonia, alde-
hyde-ammonia, C2H^O.NH:3.(p. 189), separates out. This compound is readily
soluble in water, but not so readily in alcohol, and crystallizes in large, glistening
rhombohedra, which fuse at 70°-8o°, and vaporize undecomposed in a vacuum.

On shaking aldehyde with aqueous solutions of acid alkaline sulphites, crystal-
line compounds, e.g., CH3.CHO.HSO3K (see p. 189), separate. If these be
heated together with acids, they break up into their components.

With anhydrous hydrocyanic acid, aldehyde yields CHj.CH(OH)CN (see p.
190), a liquid readily soluble in water and alcohol, and boiling with slight decom-
position at 183°. The alkalies break it up into its components, and concentrated
hydrochloric acid converts it into lactic acid.

Polymeric Aldehydes. Small quantities of acids (HCl, SOj) or salts (espe-
cially ZnClj) convert aldehyde at ordinary temperatures into paraldehyde,
(CjH^Ci^,^ (see p. 192); the change (accompanied by evolution of heat and
contraction) is particularly rapid, if a few drops of sulphuric acid be added to
the aldehyde. Paraldehyde is a colorless liquid boiling at 124°, and of sp. gr.
0.9943 at 20°. It dissolves in about 12 vols. H^O, and is, indeed, more soluble
in the cold than in the warm liquid. This behavior would point to the formation
of a hydrate. The vapor density agrees with the formula CjHjjOj. When dis-
tilled with sulphuric acid ordinary aldehyde is generated.

Metaldehyde, (C^H^Ojo, is produced by the same reagents (see above) act-
ing on ordinary aldehyde at temperatures below 0°. It is a white crystalline body,
insoluble in water, but readily dissolved by hot alcohol and ether. If heated to
Il2°-ii5°it sublimes without previously melting, and passes into ordinary alde-
hyde with only slight decomposition. When heated in a sealed tube the change
is complete.

There are many reagents that change meta- and paraldehydes to ordinary alde-
hyde and its derivatives ; e. g., PCI5 converts them 'into ethidene dichloride,
CHj.CHClj. They do not combine with NHj or alkaline bisulphites, do not
reduce silver solutions, nor do they give an aldoxime with hydroxylamine (p. 191).
Paraldehyde is not attacked by sodium, even when assisted by heat. These facts
go to prove that in the polymeric aldehydes, the aldehyde radicals are linked by
oxygen atoms (see p. 190), the same as the alkyls in the ethers. Their refractive
power and their specific volume would also indicate that the oxygen atoms present
in them are united to carbon by but one affinity.

Condensation Products. When acetaldehyde is heated with
zinc chloride, water separates and crotonaldehyde is produced : —

CH,.CHO -f CH3.CHO = CH,.CH:CH.CHO -f H^O.

2 Mols. Aldehyde. Crotonaldehyde.

By long contact with dilute sulphuric acid, aldehyde first becomes
aldol (see this) : —

CHj.CHO -I- CH3.CHO = CH,.CH(OH).CHj.CHO,

ALDEHYDES OF THE PARAFFIN SERIES. I95

and this when heated with zinc chloride, gives up water and passes
into crotonaldehyde : —

CH,.CH(OH).CH2.CHO = CHj.CHrCH.CHO + H^O.

When chlorine is conducted into cold aldehyde chlor-crotonaldehyde, CHj.
CHiCClj.CHO, and trichlorbutyraldehyde, C4H5CI3O (p. 197), are formed, and
by the action of nascent hydrogen (sodium amalgam) there results butylene glycol,
CH5.CH.OH.CH2.CH2.OH.

Sulphuric acid, sodium acetate {Berichte, 16, 786), and alkalies (sodium hy-
droxide and baryta water), exert the same power of condensation as zinc chloride
and hydrochloric acid.

Such a union of two or more molecules, by the linking of carbon
atoms (followed either with or without water separation), and the
formation of complicated carbon chains, is ordinarily termed con-
densation, distinction being made at the same time between the
aldol condensation and genuine aldehyde condensation, in which an
exit of water does occur.

In the case of the higher aldehydes (also ketones), the condensa-
tion is so made that the oxygen of aldehyde unites with the hydro-
gen of a CH2 group. Thus, from propylaldehyde we get methyl-
fethyl acrolein : —

CjHj.CHO + CH /^^=C,Hj.CH:C(CH3).CH0 + HjO.

The aldehydes act in a perfectly similar manner upon the esters
of malonic acid, CH2(C02R)2, acetic acid and analogous com-
pounds {Annalen, 218, 121).

Another very remarkable condensation is sustained by the alde-
hydes through the action of ammonia (heating of aldehyde-ammo-
nias) ; nitrogenous bases (pyridine bases) are produced.

Substituted Aldehydes. These are obtained by the action of chlorine upon
acetaldehyde or ethyl alcohol, the latter being simultaneously oxidized to aldehyde.
The only pure compound that can be formed in tRis manner is the final chlorina-
tion product, trichloraldehyde.

Monochloraldehyde, CHjCl.CHO, is obtained pure by distilling monochlor-
acetal, CH2C1.CH(0.C2H5)2, with anhydrous oxalic acid. It is a Uquid that
boils at 85°, and polymerizes very rapidly to a white mass {Berichte, 15, 2245).
%Vhen oxidized it yields monochloracetic acid ; with CNH and hydrochloric acid
it becomes ;3-chlorlactic acid.

Dichloraldehyde, CHClj.CHO, is produced in the distillation of dichloracetal,
CHCL.CHfO.CaHs)^, with concentrated sulphuric acid. It boils at 88°-90°,
and when preserved, changes into a solid polymeric modification. The hydrate,
CHCl-.CHO + HjO, corresponding to chjoral hydrate, fuses at S7° and boils
at 110°. When it is oxidized with HNO3 dichloraldehyde is converted into
dichloracetic acid. It yields dichloriactic acid by the action of CNH and hydro-
chloric acid.

196 ORGANIC CHEMISTRY.

Trichloracetaldehyde, CCI3.CHO, Chloral, is best prepared
by conducting chlorine into alcohol and distilling the crystalline
product with sulphuric acid. It is an oily, pungent-smelling liquid,
which boils at 97°, and has the sp. gr. 1.541 at 0°. With NH3,
CNH, acid sulphites of the alkali metals, etc., chloral furnishes
compounds similar to those of ordinary aldehyde ; it also reduces
an ammoniacal silver solution. When kept for some time it passes
into a solid polymeride. It yields trichloracetic acid when oxid-
ized by HNO3. When heated with alkalies it breaks up into
chloroform and a formate : —

CCI3.CHO + KOH = CCI3H 4. CHO.OK.

When it combines with a small quantity of water chloral
changes to ynvf

Chloral Hydrate, C2HCI30.HjO = CC1,.CH^q^, which con-
sists of large monoclinic prisms, fusing at 57° and distilling at
96—98°. The vapors dissociate into chloral and water. Chloral
hydrate dissolves readily in water, possesses a peculiar odor and
a sharp, biting taste ; when taken internally it produces sleep.
Concentrated sulphuric acid resolves the hydrate into water and
chloral.

Chloral and alcohol combine to Chloral Alcobolate, — trichlorethidene ethyl

ether— CCl3.CH(^9j^'' ° a crystalline solid, fusing at 56° and boiling at 114-

115°. When acetyl chloride is allowed to act upon the preceding derivative
the acetyl ester, trichlorethidene ethyl acetin, is produced. This boils at ig8°.
Concentrated sulphuric acid reproduces chloral from the alcoholate.

Acetic anhydride and chloral yield trichlorethidene diacetate, CCl3.CH(O.Cj
H30)2,which boils at 221°. It unites with ammonia to form chloral-ammonia, —

trichlorethidene hydramine — CCl,.CH^-.,„ , melting at 63°. With prussic

^ ^ TT /OH

acid it furnishes chloTal-cyanhydrate, CCI3.C (' p^ a crystalline derivative,

fusing at 61-62°, and passing into trichlorlactic acid when treated with hydro-
chloric acid.

Dibromacetaldehyde, CHBr2.CH0, oblained by the bromination of alde-
hyde or paraldehyde, is a liquid, boiling at 142°. After standing some time it
becomes solid — a polymeric modification. It yields a crystalline hydrate with

water. It combines with CNH to form the compound, CHBr2.CH^„TT, from
which dibromlactic acid may be obtained. ^

Tribromaldehyde, CBrj.CHO, Bromal, is perfectly analogous to chloral.
It boils at 172-173°, and with water forms a solid hydrate fusing at 53°. The
alcoholate melts at 44° and decomposes at 100°. Heated with alkalies bromal

breaks up into bromoform and a formate. It yields a cyanide, CBrj.CH^ P^
with CNH and this hydrochloric acid converts into tribromlactic acid.

3-^""\CN,

ft

ALDEHYDES OF THE PARAFFIN SERIES. I97

lodo-acetaldehyde, CHjT.CHO, is made by acting on aldehyde with iodine
or iodic acid. It is an oily liquid, with a very disgusting odor ( Berichte, 22, Ref.
561). Silver cyanide converts it into cyanaldehyde, C2H3(CN)0 {Berichte, 22,
Ref. 563).

Sulphur Compounds. — On passing hydrogen sulphide into an aqueous solu-
tion of aldehyde the reaction proceeds in the same manner as with formic aldehyde.
In the presence of hydrochloric acid two isomeric trithioaldehydes, (CjH^S),,
are produced. They crystallize in long needles and prisms, a- Tnthioaldehyde
melts at 101°, and the ^- modification at 120°. Both boil about 245°. Concen-
trated HjSOj, or acetylchloride, converts the a- into the j3- variety. When oxid-
ized with KMnOj both varieties yield the same Trialdehydetrisulphone, (CH,.
CH)3(SOj)3 {Berichte, 22, 2600; 23, 60).

Thialdin, CjHjjNS,, separates on conducting H^S into an aqueous solution of
aldehyde-ammonia. It consists of large, colorless crystals, fusing at 43°. It is a
monacidic, secondary base, and may be viewed as a. trithioaldehyde in which an
atom of sulphur is replaced by the imide group, inasmuch as it can also be made
by allowing ammonia to act upon trithioaldehyde. In a similar manner methyl-
amine produces Methylthialdin, (<Z^^^.^(^.Q'&^, melting at 19° {Berichte, 19,
2378)-

3. Propionic Aldehyde, CsHjO = CjHj.CHO, is obtained
from normal propyl alcohol, and by the dry distillation of calcium
propionate an3 formate. It is very similar to acetaldehyde, boils
at 49°, and has a sp. gr. 0.8066 at 20°. It is soluble in 5 vols. HjO
at 20°. With PCI5 it yields QH5.CHCI2.

Propyl Aldoxime, CjHj.CHtN.OH (see p. 191), boils at 131°.

/3-Chlorpropionic Aldehyde, CHjCl.CHj.CHO. This is produced when HCI
is added to acrolein ; it fuses at 35°, and, when distilled, again breaks up into
acrolein and HCI. Nitric acid oxidizes it to /3-chlorpropionic acid.

4. Butyraldehydes, Q.^fi = C3H7.CHO. Two isomeric
aldehydes of this form exist ; they correspond to the two primary
butyl alcohols.

(i) Normal Butyraldehyde, CH3.CH.2.CH2.CHO, from nor-
mal butyl alcohol and normal butyric acid {^Berichte, 18, 3364), is
a liquid boiling near 75°, and has a sp. gr. 0.8170 at 20°. It dis-
solves in 27 parts HjO, and oxidizes readily to butyric acid.
Heated with alcoholic ammonia it yields the base paraconine,
CsHijN, boiling at 170° and very similar to conine, CsHnN.
The isomeric paraconine obtained from isobutyraldehyde boils at
146°.

3-Chlorbutyraldehyde, CHj.CHCl.CH^.CHO, is produced from crotonalde-
hyde, CH3.CH:CH.CHO, by the addition of HCI, and consists of needles, fusing
at 96°. Nitric acid oxidizes it to /3-chlorbutyric acid.

Trichlorbutyraldehyde, CH3.CHCl.CClj.CHO, formerly obtained from croton-
aldehyde, C^HjClgO, is produced by the action of chlorine upon acetaldehyde or
paraldehyde, the first product being chlorcrotonaldehyde, CHg.CH:CCl.COH
(p. 195), which further unites with C\, yielding butylchloral {Annalen, 219, 374).

198 ORGANIC CHEMISTRY.

The latter compound, like the ordinary chloral, is a heavy, oily liquid, boiling at
163-165°, and forming with water the hydrate, C4H5CI3O + H,0; this last crys-
tallizes in tablets, fusing at 78°. The alkalies decompose butyl chloral into acetic
acid, potassium chloride and allylene dichloride, CHjCChCHCl. It yields a
trichlorbutyric acid when oxidized with nitric acid.

(2) Isobutyraldehyde, (CHa^CH.CHO, obtained from fer-
mentation butyl alcohol and calcium isobutyrate, has the sp. gr.
0.7898 at 20°, and boils at 63°. It dissolves in nine volumes of
water at 20°- A small quantity of concentrated sulphuric acid
converts it into Para-isobutyraldehyde, (C4H80)3, which crys-
tallizes in brilliant needles, melting at 60°, and boiling at 194°.

5. Atnyl Aldehydes, CjHj^O = C^Hg.CHO, Valeraldehydes. There are four
possible isomerides ; two of these are known : —

Normal Amyl Aldehyde, (CH3)(CHj,)3CHO, from valeric acid, boils at 102°.
Isoamyl Aldehyde, (CHjJj.CH.CHj.CHO, from the amyl alcohol of fermenta-
tion and from isovaleric acid, is a liquid, with fruit-like odor, boiling at 92°, and
polymerizing readily. When oxidized it becomes isovaleric aCid. On heating
with alcoholic ammonia to 150° it yields two basic compounds, valeridine, CjjHjjN,
and valeritrine, CjjHjjN, which boils near 250°.

Normal Hexyl Aldehyde, CjHuO = CjHu.CHO, Caproyl Aldehyde, from
caproic acid, boils at 128°. Normal Heptyl Aldehyde, 0,^1^0, cenanthylic
aldehyde, or oenanthol, is produced along with hendecatoic acid in the distilla-
tion of castor-oil, best under diminished pressure. It is a pungent-smelling liquid,
boiling at 153-154°. It becomes normal heptylic acid, CjHjjOj, when oxidized
with dilute nitric acid (i : 2 vols. H^O).

The higher aldehydes are most advantageously prepared by the distillation,
under diminished pressure, of the barium salts of the corresponding fatty acids
with barium formate {Berkhte, 16, 1716). Like their acids, they all have normal
structure. They can be boiled without decomposition only under a somewhat
diminished pressure.

Decatoic Aldehyde, CjjHjuO, Capric Aldehyde, obtained from capric acid,
boils at 106° under a pressure of 15 mm.

Dodecatyljc Aldehyde, CuHj^O, Laurie Aldehyde, from lauric acid, crys-
tallizes in shining tablets, fusing at 44.5°, and boiling at 142° (22 mm.).

Tetradecatylic Aldehyde, Ci^Hj^O, Myrisitaldehyde, made from myristic
acid, melts at 52.5°, and under 22 mm. pressure boils at 168° C.

Hexdecatylic Aldehyde, C1JH32O, Palmitic Aldehyde, from palmitic acid,
fuses at 58.5°, and under 22 mm. pressure boils at 192° C.

Octdecatylic Aldehyde, C^^^, Stearaldehyde, consists of tablets having
a bluish lustre. It fuses at 63.5°, and boils at 192° C. (under 22 mm. pressure).

2. UNSATURATED ALDEHYDES, CoH2„_jO.

These derivatives bear the same relation to the alcohols of the
allyl series as the aldehydes just considered bear to the alcohols
CoH^n + jO, of the saturated hydrocarbons. Inasmuch as they are
unsatiirated compounds they are capable of directly saturating two
affinities.

The first and lowest member of the series is : —

UNSATURATED ALDEHYDES. 199

Acrylaldehyde, CsH^O = CH^tCH.CHO, or Acrolein. This
is produced by the oxidation of allyl alcohol and by the distillation
of glycerol or fats : —

CsH^COH), = qH,0 + 2H,0.

Glycerol.

One part of glycerol is distilled with two parts of acid potassium sulphate. The
distillate is redistilled over lead oxide (Annalen, Suppl., 3, 180).

Acrolein is a colorless, mobile liquid, boiling at 52°, and possess-
ing a sp. gr. of 0.8410 at 20°. It has a pungent odor and attacks
the mucous membranes in a frightful manner. The odor of burn-
ing fat is occasioned by acrolein. It is soluble in 2-3 parts water.
It reduces an ammoniacal silver solution, with formation of a mirror-
like deposit, and when exposed to the air it oxidizes to acrylic acid.
It does not combine with primary alkaline sulphites. Nascent
hydrogen converts it into allyl alcohol.

Phosphorus pentachloride converts acrolein into propylene dichloride, CHj :
CH.CHClj, boiling at 84° C. With hydrochloric acid it yields ;3.chlorpropionic
aldehyde (p. 197). With bromine it yields a dibromide, CHj.Br.CHBr.CHO,
which becomes /3-dibrompropionic acid upon oxidation.

When preserved, acrolein passes into an amorphous, white mass {disacryf). On
wanning the HCl compound of acrolein (see above) with alkalies or potassium
carbonate metacrolein is obtained. The vapor density of this agrees with the
formula (031140)3. It crystallizes from alcohol in tablets, fusing at 45-46°, and
dissociating at 160° C.

Ammonia changes acrolein to the so-called acrolein- ammonia, CjHjNO +
;^H,0 :—

2C3H4O + NH3 = CjHjNO + HjO.

This is a yellowish mass that on drying becomes brown, and forms amorphous
salts with acids. It f\Ads, picoline, CjH^N (methyl-pyridine, CjHjN.CHj), when
distilled.

Crotonaldehyde, QHeO = CHg.CHiCH.CHO, is obtained
by the condensation of acetaldehyde (p. 194) when heated with
dilute hydrochloric acid, with water and zinc chloride, or with a
sodium acetate solution, to 100° C. {Berichte, 14, 5i4and 516) : —

CH3.CHO + CH3.CHO = CH3.CH:CH.,CH0 + H^O.

It is also produced when the sulphuric acid solution of brom-
ethylene is boiled with water (see p. 134). Crotonaldehyde is a
liquid with irritating odor, soluble in water ; at 0° it has a sp. gr.
of 1.033, 3.nd boils at 104-105°- On exposure to the air it oxidizes
to crotonic acid ; it reduces silver oxide. It combines with hydro-
chloric acid to form /9-chlorbutyraldehyde (p. 197) ; on standing
with hydrochloric acid it unites with water and becomes aldol. Iron

20O ORGANIC CHEMISTRY.

and acetic acid change it to croton-alcohol, butyraldehyde and
butyl alcohol.

o Chlorcrotonaldehyde, CHj.CHiCCl.CHO, is a by-product in the prepara-
tion of butyl-chloral, and may also be obtained by the condensation of aldehyde
with monochloraldehyde. It is a pungent-smelling oil, boiling at 150°. It com-
bines directly with two atoms of chlorine to butyl chloral (p. 197).

When the alcoholic solution of acetaldehyde-ammonia is heated to 120°, Cro-
tonal-ammonia, CgHjgNO (Oxtetraldine), is produced. This bears the same
relation to crotonaldehyde that acrolein-ammonia does to acrolein. It is a brown
amorphous mass, yielding amorphous salts with acids. When heated it breaks
up into water and collidine, CgHjjN = trimethylpyridine, C5H2N(CH3)5.

Methyl-ethyl Acrolein, C2H5.CH:C(CH3).CHO, is produced by the con,
densation of propionic aldehyde (p. 195), and boils at 137° C.

KETONES.

The ketones are characterized by the group CO in combination
with two alkyls. They share many analogies with the aldehydes,
indicated by the similar methods of production (see p. 186). We
have the following specific methods for their formation : —

1. The action of the zinc alkyls (i molecule) upon the chlorides
of the acid radicals (2 molecules) : —

2C2H5.COCI 4- Zn(CH3)j = 2C2H5.CO.CH3 + ZnClj,

Propionyl Chloride. Methyl-ethyl Ketone,

2CJH5.COCI + Zn(CjH5)j = 2C2H5.CO.CjH5 + ZnClj.
Diethyl Ketone.

To the zinc alkyl (l molecule), cooled by ice, there are added drop by drop at
iirst, then rapidly, 2 molecules of the acid chloride, and the product of the reaction
is immediately decomposed by a large quantity of water. The reaction is similar
to that occurring in the formation of the tertiary alcohols (p. 120). At first the
same intermediate product is produced : —

fC^Hg

CH3.COCI + Zn(CjH5), = CHg.C-^ O.Zn.CjH5,

I CI

which (with a second molecule of the acid chloride) afterwards yields the
ketone : —

CH3.C J O.ZnXjHs + CH3.COCI = 2CH3.CO.CjH5 + ZnClj.

In many cases, especially in the preparation of the pinacolines, it is, however,
more advantageous to employ double the quantity of the zinc alkyl (l molecule to I
molecule acid chloride) which will serve to dilute the mixture {Annalen, 188,
144) ; in this manner the intermediate product forms the ketone with water, and
there occurs a. simultaneous evolution of paraffins. The aqueous solution is dis-
tilled, and the ketone separated from it by means of soda.

2. By the action of anhydrous ferric chloride upon the acid radicals. At first
hydrochloric acid gas is evolved and an intermediate product formed, which is

KETONES. 20 1

changed by water and evolution of CO^ into a ketone {Berichte,i2, Ref. 141)
Propinyl chloride, treated as above, yields diethyl ketone : —

/CH3

2C,H5.COCl = qH5.CO.CH<;^^^3,j _,. HCl

HCl.

and C,H,.CO.CH/^g3,^ + H,0 = C,H,.CO.C,H, + CO, +
Butyryl chloride, CjHj.COCl, yields dipropyl ketone, CjHj.CO.CjH,.

3. The oxidation of the acids of the lactic series with secondary
alkyls, by means of bichromate of potash and dilute sulphuric acid
(see p. 1 88): —

(CH,),C(OHVCO,H + O = (CH,),CO + CO, + Hp.

Oxyisobutyric Acid. Dimethyl Ketone.

4. The decomposition of the aceto-acetic acids and their esters
(see these) : —

CH,.CO.CHj.COj.CjH5 + HjO = CH3.CO.CH3 + COj + CjHj.OH.

The ketones are also produced in the dry distillation of wood,
sugar, and many other carbon compounds.

The names of the ketones are derived by combining the names
of the alkyls with the syllable ketone. A. Baeyer regards the ketones
as keto-substitution products of the hydrocarbons resulting from the
replacement of two hydrogen atoms by one atom of oxygen. Ac-
cordingly dimethyl ketone, CHs.CO.CH3, is called ketopropane,
ethyl-methyl ketone, C2H5.CO.CHs, a-ketobutane, etc. {Berichte,
19, 160).

The ketones are generally ethereal-smelling, volatile liquids, in-
soluble in water. They do not reduce ammoniacal silver solutions.
They combine, like aldehydes, with the primary alkaline sulphites ;
but it appears that only those of the higher ketones, in which the
group CO is in combination with the methyl group, are adapted to
this reaction. Boiling alkaline carbonates again separate the ketone
from these compounds (p. 190). Hence, these reactions serve both
for the isolation and the purification of these derivatives.

Nascent hydrogen (sodium amalgam) converts them into second-
ary alcohols: —

(CH3)jC0 + Hj = {CH3)jCH.0H.

At the same time there occurs here, as with the aldehydes (p. 194), a condensa
tion of the ketone molecule, accompanied by the formation of dihydric alcohols : —

(CH3)jC.OH
2(CHs),C0 -f Hj = I

(CH3),C.0H.

17

202 ORGANIC CHEMISTRY.

These are termed pinacones. When heated with acids they sustain a peculiar
transposition of atoms, and are converted into ketones : —

(CH3),C.0H (CH3),C

I = >CO + H,0.

(CH3)2C.OH CVL/

Tertiary Butyl-methyl Ketone.

Such ketones, containing a tertiary alkyl group, are designated pinacolines.
They may be synthesized by the action of zinc alkyls upon the chlorides of such
fatty acids as contain tertiary alkyls : —

(CH3)sC.COCl yields (CH3)3C.CO.CH3.
Trimethyl Acetyl Pinacoline.

Chloride.

The ketones also unite with HCN, forming oxycyanides, e.g., (CH3)jC(0H).
CN (see Berichte, 15, 2306), from which the corresponding oxyacids may be ob-
tained (see p. 190). Similarly, acetone in the presence of caustic soda combines

with chloroform, yielding acetone chloroform, (CH3)jC;^ pq This, too, can

be converted into the corresponding oxyacid.

All the ketones (like the aldehydes, p. 191) combine with hydroxylamine, and
become oximid- or isonitroso- compounds, called acetoximes, or ketoximes (see p.
20s) :—

(CH3)jCO + HjN.OH = (CH3)2C:N.OH + HjO.

To prepare the ketoximes the ketones are allowed to stand for some time with
hydroxylamine hydrochloride. The reaction is accelerated by heating in a water-
bath, or in a sealed tube. Frequently the reaction will only occur in feebly alkaline
solutions. Soda or caustic soda is then added in equivalent amount. At times a
great excess of caustic soda (3 mol.) must be added [Berichtt, 22, 605). Instead
of using hydroxylamine hydrochloride, potassium hydroxylamine-disulphonate (re-
ducing salt) may be used (Annalen, 241, 1S7). This salt is obtained by acting
upon sodium nitrite with monosodium sulphite.

The acetoximes, like the aldoximes, are split up into their compo-
nents when boiled with acids. They are similarly transformed into
amine's by sodium amalgam and acetic acid (p. 160). . They are
distinguished from the aldoximes in that the latter yield nitriles
with acetyl chloride, while the acetoximes, under like influence,
form oils with peculiar odor. Nitrogen tetroxide converts the ketox-
imes into pseudo-nitrols.

Acetoximes with tertiary hydrogen atoms, readily suffer molecular rearrange-
ments under the influence of acetyl chloride {Berichte, 20, 506) : — .

(CH3)jCH. (CH3),CH.CO

>C(N.OH) yields I

{CH.,\CR'^ (CHs)jCH.NH.

Di-isopropyl Acetoxime. Isobutyryl-isopropyl

Amine.

>C(N.OH) yields

I
Acetoxime. Ii

All ketoximes sustain an analogous transformation by the action of hydrochloric.

KETONES. 203

sulphuric or acetic acid. Thus, methyl-propyl-ketoxime yields acetopropyJamine
{Beckmann, 21, 2530) : —

C3H,.C(NOH).CH3 = ,C3H,.NH.CO.CH3.

All bodies possessing the ketone group CO (or the aldehyde group), e. g., the
ketonic acids and alcohols, react with hydroxylamine in a manner similar to that
of the ketones. Some acid anhydrides, e.g., phthalic anhydride [Berichte, 16,
1780), do the same. This is not, however, the case with the lactones and alky-
len oxides. The diketones, such as glyoxal, CHO.CHO, are capable of a double
reaction with hydroxylamine, yielding compounds known as acetoximic acids or
glyoximes. The ketones react more readily with phenylhydrazine, forming crystal-
line compounds (the hydrazones) than with hydroxylamine {Berichte, 17, 576 ; 16,
661; 20,513).

BoiUng nitric acid converts the ketones into dinitroparaffins. In this reaction
the nitro-groups attach themselves to the higher alkyl of the mixed ketones. The
ketones (like the aldehydes, p. 191) form mercaptols with the mercaptans.

The ketones cannot be directly oxidized. When they are boiled with KjCrjO,
and dilute sulphuric acid, they break up in such a manner that the CO group
passes out in combination with the lower alkyl, thus producing an acid. Should
the other higher alkyl chance to be of a primary character, it, too, will be oxidized
to an acid : —

CH3.CH,.CH:>C0 + 30 = CH3.CO.OH + CH3.CH,.C0.0H.

Methyl Propyl Acetic Acid. Propionic

Ketone. Acid.

When the higher radical is secondary, it first becomes a ketone, and this de-
composes further : —

(CH3).Ch0cO -f 20 = CH3.CO.OH + (CH3).CO.

Methyl Isopropyl Acetic Acid. Acetone.

Ketone.

When the CO group is united to carbon atoms carrying an equal number of
hydrogen atoms, it remains with the higher alkyl when decomposition occurs
{Berichte, 15, 1 194). For further details of the decomposition, see Benchte, 18,

2266, and Ref. 181. . . . , , 1

To oxidize ketones, proceed as follows : dilute a mixture consisting of i molecule
ketone, l molecule KjCr^Oj and 4 molecules H^SO^, with 5-10 parts water, and
heat the same in a large flask, provided with a long, upright glass tube serving
as a condenser. The reaction is complete when the mixture assumes the pure,
green color of chromium sulphate (compare Annalen, 190, 349) :—

K,Cr,0, + 4H,SO, = (SO,)3Cr, + K,SO, + 4H,0 + 3O.

The acids produced are distilled over with water.

A similar decomposition is sustained by the ketones when oxidized by free
chromic acid, potassium permanganate, PbOa, etc. {Annalen, 186, 257.)

Dimethyl Ketone, C3H3O = (CHs^CO, Acetone. In addi-

204 ORGANIC CHEMISTRY.

tion io the general methods of formation, acetone is produced by
heating chlor- and brom-acetol (p. loi) with water to i6o°-i8o° : —

CH3.CCI2.CH3 + H20 = CH3.CO.CH3 + 2HCI;

and also by the dry distillation of tartaric and citric acids, sugar,
wood, etc. This accounts for its presence in crude wood spirit
(p. 124). It is usually obtained by the dry distillation of calcium
acetate (p. 187). It occurs, too, in small quantities in the blood
and normal urine, while in the urine of those suffering from diabetes
it is present in corisiderable amount.

Of theoretical interest is its formation from /3-chlor- and brom-propylene,
CHj.CBriCHj, -when these are heated with water to 200°, or dissolved in sul-
phuric acid and boiled with water. We would naturally expect an alcohol, CHg.
C(OH):CH2, to be formed here, but a transposition of atoms occurs and acetone
results (see p. 134). Acetone is similarly formed from allylene, CHj.C: CH, by
action of sulphuric acid or HgBr^ in the presence of water (p. 87).

Acetone is a mobile, peculiar-smelling liquid, boiling at 56.5°
and having a sp. gr. of 0.7920 at 20°. It is miscible with water,
alcohol and ether. Calcium chloride or other salts set it free from
its aqueous solution. The compound it forms with primary sodium
sulphite has one molecule of water, and consists of pearly scales,
easily soluble in water. Excess of sodium sulphite or alcohol sepa-
rates it from its solution. When in aqueous solution, sodium amal-
gam converts it into isopropyl alcohol. The chromic acid mixture
oxidizes it to acetic and formic acids, which, as a general thing,
are still further oxidized to CO2 and water : —

CH3.CO.CH3 -f 3O = CH3.CO.OH -1- CHO.OH'.

Acetic Acid. Formic Acid.

The ketones are similarly decomposed when their vapors are con-
ducted over heated soda-lime.

An aqueous acetone solution, mixed with KOH and an iodine solution, yields
iodoform (p. 103). This reaction (Lieben) serves to detect acetone even in pres-
ence of alcohol (Berichte, 13, 1004). All ketones containing the group CO.CH3,
do the same (Berichte, 14, 1948). In the presence of alcohol it is better to use an
iodine solution and ammonia, for then the alcohol will not yield iodoform (Gun-
ning, Berichte, 17, Ref. 503). According to the reaction of Weyl and Legal-,
sodium nitroprusside and sodium hydroxide impart a brown-red color in the pres-
ence of acetone (Berichte, 17, Ref. 503, and 18, Ref. 19S). "
vert acetone into chlor- and brom-acetol (p. loi).

Acetone Substitution Products result by the direct action of chlorine or
bromine upon acetone and by various other methods.

Monochloracetone, CHj.CO.CHjCl, is obtained by conducting chlorine into

KETONES. 205

cold acetone (Berichte, 19, Ref. 48), or by the action of hypochlorous acid upon
monochlor- or monobrom-propylene : —

CHj.CBnCH^ + ClOH = CH3.CO.CH2CI + HBr.

It is a liquid, insoluble in water; its vapors provoke tears.

There are two possible Dichloracetones, CaHjCl^O: (a) CHg.CO.CHCl^ and
(;8) CHjCl.CO.CHjCl. The first is formed on treating warmed acetone with
chlorine, and is obtained from dichloraceto-acetic ester, on boihng the same with
hydrochloric acid. {£erichle,i$, 1164.) It is an oily liquid, with a sp. gr. of
1.236 at 21°, and boils at 120°. The ;3-dichloracetone is produced in the oxida-
tion of dichlorhydrin, CH5Cl.CH(OH).CH2Cl (see glycerol), with potassium
dichromate and sulphuric acid. {Berichte, 13, 1701.) It consists of rhombic
plates, fusing at 45°, and boiling at I72°-I74°.

For other chloracetones, see Berichte, 20, Ref. 48.

Symmetrical Tetrachloracetone, CHCl^.CO.CHClj, is readily obtained by the
action of potassium chlorate and hydrochloric acid upon chloranilic acid {Berichte,
ai, 318) and triamidophenol {Berichte, 22, Ref. 666), or of chlorine upon the
finest phloroglucin {Berichte, 22, 1478). It is a yellow oil. Under a pressure of
725 mm. it boils at 180°. It combines readily with water to the hydrate CjHj
CI4O + 4HjO, crystallizing in large prisms, and melting at 48°. It unites to the
corresponding acid with HCN {Berichte, 22, Ref. 810). Bromine yields similar
substitution products.

Monobromacetone, CH3Br.CO.CH3, and Symmetrical Dibromacetone,
CHj.Br.CO.CHjBr {Berichte, 21, 3288) are oils. They can only be distilled under
reduced pressure.

lodo-Acetone, CHj.CO.CHjI, is produced when iodine and iodic acid act
upon acetone. It is a heavy oil with a disagreeable odor {Berichte, 18, Ref 330).

/3-Di-iodoacetone, CHjI.CO.CHjI, forms when iodine chloride acts upon
acetone. It fiises at 62° and decomposes about 120°.

Liquid apetone-chloroform is produced by the action of chloroform and caustic
alkali upon acetone. It boils at 170°. In moist air it passes into the isomeric solid
Acetone-chloroform, (CH,)j.C(0H).CCl3 (compare p. 202). This consists of crys-
tals, melting at 97° and boiling at 167°. They have an odor like that of camphor.
Aqueous alkalies convert it into oxyisobutyric acid. Two complex acids result in
the presence of acetone {Berichte, 20, 2449).

Acetone-eyanhydrin, (CH3)j.C(OH).CN, is obtained from acetone and CNH.
It is a liquid, boiling at 120°.

Hydrogen sulphide converts acetone into Trithioacetone, {C3H5S)3. This is
analogous to trithioaldehyde. Colorless needles, melting at 24° and boiling at 230°
{Berichte, 22, 2592). KMnOj oxidizes this compound to Triacetone-trisulphone,

fCH.I.C-^oS^ ~ S'/SS'^^SO,. This also results from the action of NaOH and

CH3I upon trimethylene trisvilphone (p. 193) {Berichte, 22, 2609; 23, 71).

Hydroxylamine- or Oximido-Derivatives (p. io6 and p.
202). Acetoxime, (CH3)2C:N.OH, dimethylacetoxime, formed
in the action of hydroxylamine upon acetone (p. 202) {Berichte,
20, 1505), is a compound readily soluble in water, alcohol and
ether. It fuses at 60° and boils at 135°. Boiling acids regenerate
acetone and hydroxylamine.

2o6 ORGANIC CHEMISTRY.

Hypochlorous acid converts acetoxime into an ester, (CH3)2.C:N.O.CI. This is a
liquid with an agreeable odor. It boils at 134°. It explodes when rapidly
heated {^Berichte, ao, 1505).

The hydroxyl hydrogen present in this compound may be replaced by acid
radicals through the agency of acid chlorides or anhydrides. With sodium alco.
holate.the sodium derivative results, which yields the alkyl ethers, (CH3)jC:N.OR,
when acted upon by the alkylogens. On boiling these ethers with acids, acetone
and alkylized hydroxylamines, NHpR {Berichte, 16, 170), are produced. The
higher acetoximes show a perfectly analogous deportment.

Isonitroso-acetone, CHa.CO.CHiN.OH. This is obtained
from the isonitroso-aceto-acetic ester (^Berichte, 15, 1326). Nitrous
acid converts aceto-acetic acid directly into isonitroso-acetone and
carbon dioxide : —

CH3.CO.CH2.CO2H + ON.OH = CHa.CO.CH(N.OH) + CO^ + HjO.

The isonitroso-derivatives of the higher acetones are made directly, after the
same manner, from monoalkylized aceto-acetic acids and their esters {Berichte, 20 ,

530 •—

CH3.CO.Ch/^O^jj + NO.OH = CH.3CO.c/^ QH + CO, + H,0.

The dialkylic aceto-acetic acids are not reactive {Berichie, 15, 3067).

The isonitrosoketones are the direct product of the action of amyl nitrite, in
presence of sodium ethylate or hydrochloric acid, upon the ketones. At times
sodium ethylate and again hydrochloric acid gives the best yield (^Berichte, 20, 2194;
22, 526) :—

CH3.CO.CH3 + NO.O.C5H11 = CH3.CO.CH(N.OH) + C5H11.OH.

An excess of amyl nitrite decomposes the isonitroso-compound. The isonitroso-
group is replaced by oxygen and a-diketone compounds are produced at the same
time (Berichte, 22, 527).

Isonitrosoketones are also produced by the action of nitrogen trioxide upon the
ketones (Berichte, 20, 639J.

The isonitroso-acetones are colorless, crystalline bodies, readily
soluble in alcohol, ether and chloroform ; but, as a general thing,
they dissolve with difficulty in water. They impart an intense
yellow color to their alkaline solutions, and with phenol and sul-
phuric acid yield a yellow coloration, but not the nitroso-reaction
(see p. 107). When boiled with concentrated hydrochloric acid
they lose hydroxylamine.

The isonitroso-group of the isonitroso-ketones can be split off and replaced by
oxygen. The result will be diketo-compounds, CO.CO. This transformation may
be effected by the action of sodium bi^lphite, and subsequent boiling of the result-
ing imidosulphonic acids with dilute acids [Berichte, 20, 3162). The same effect is
obtained by directly boiling the isonitrosoketones with dilute sulphuric acid {Berichte,
20, 3213). Nitrous acid sometimes produces the decomposition even more readily
(Berichte, 22, S32).

KETONES. 207

Isonitroso-acetone, CH3.CO.CH(N.OH), is very readily soluble
in water; crystallizes in silvery, glistening tablets or prisms; fuses
at 65°, and decomposes at higher temperatures, but may be volatil-
ized in a current of steam.

By the action of sodium alcoholate upon benzylcMoride we get the benzyl-
ether, which is isomeric with benzyl- isonitroso-acetone, obtained from benzyl-
aceto acetic acid : —

CH,.CO.CH:N.O.C,H, and CH3.CO.C ' '

%N.OH.
Isonitrosoacetone-benzyl Ether. Benzyl-isonitrosoacetone.

This is proof sufficient of the presence of the oximid-group N.OH in the isoni-
troso compounds (Berichte, 15, 3073). -For the salts of the isonitrosoketones con-
sult Berichte, 16, 835.

Dehydrating agents, like acetic anhydride, convert the isonitrosoketones into
acidylcyanides {Berichte, 20, 2196).

When the isonitroso-acetones are reduced with tin and hydrochloric acid they
yield peculiar bases, called ketines (CjHjNj, ketine, CgHj ^Nj, dimethyl ketine).
Phenylhydrazine (2 mols.) converts the isonitrosoketones into osazones, e. g.,
acetone-osazone, CH5.C(N2H.C«H5).CH(NjH.CeH5).

Any further action of hydroxylamine (or its HCl salt, Berichte, 16, 182)
upon isonitroso-acetone (or upon a-dichloracetone, CHj.CO.CHClj) leads to a
replacement of the ketone oxygen and the formation of

Acetoximic Acid, CH3.C(N.OH).CH(N.OH), or Methylglyoxime, a deri-
vative of glyoxime, CH(N.OH).CH(N.OH), (see p. 202) obtained from glyoxal,
CHO.CHO. 'The(/!a%/.^/)/oj^'»««j,likeCH3.C(N.OH).C(N.OH).CH3,dimethyl-
glyoxime, are similarly derived from the higher isonitrosoketones. The glyoximes
are solid, crystalline bodies, which dissolve with difficulty in water, and sublime
without decomposition. Afethyl glyoxime mAls 3.1 153°; methyl-ethyl glyoxime ^\.
170°. Glyoxime and methyl glyoxime show an acid reaction, and dissolve in
alkalies without imparting color, because the hydrogen of the CH-group is
replaced. The dialkylic glyoximes, on the other hand, are insoluble in alkalies
and do not yield salts {Berichte, 16, 180, 506, and 2185).

Di-isonitroso-acetone, CH(N.OH).CO.CH(N.OH),is formed when nitrous acid
acts upon acetone-dicarboxylic acid. A crystalline compound, melting at 144°.
The acid solution rapidly decomposes on heating. It forms crystalline, yellow
salts with alkalies {Berichte, ig, 2465).

Hydroxylamine converts this compound into Tri-isonitroso-propane, CH(N.OH).
C(N.OH).CH(N.OH). This crystallizes from water and alcohol in colorless
needles, melting at 171° {Berichte, 21, 2989).

For the compounds of acetone and isonitroso-acetone with phenylhydrazme see
the latter and Berichte, 11, 2995 ; ^2,528. , , r.^^ u

Condensation Products.— '&y the action of dehydrating agents (H^SO^, burnt
lime, zinc chloride, hydrochloric acid) and sodium, acetone (like aldehyde, p. 19S)
loses a molecule of water, and condenses to complex molecules. Mesityl oxide,
phorone and raesitylene are produced in this way : —

2C3H,0 = CeH»0 + H,0
Mesityl Oxide.

3C3H3O = CgHi.O -h 2H,0.

Phorone.

2o8 ORGANIC CHEMISTRY.

To prepare mesityl oxide and phorone, saturate acetone with HCl and let stand
for some time, then treat the product with aqueous potash. On diluting with water
an oily liquid separates, consisting of mesityl oxide and phorone, which are sepa-
rated by fractional distillation [Anna/en, i8o, 4).

Mesityl Oxide, CgHi^O, is 1 mobile liquid, smelling like peppermint and
boiling at 130°. It acts like acetone ; it takes on hydrogen, combines with sodium
bisulphite and forms a chloride, CgHmCl^, with PCI5. When boiled with dilute
sulphuric or hydrochloric acid mesityl oxide decomposes into two molecules of
acetone. It combines directly with Br^ and HI.

Mesitonic or dimethyl-lsevulinic acid, CjHjjOj, is a derivative of mesityl oxide
{Berichte, 21, Ref. 643).

Phorone, CjHj^O, crystallizes in large, yellow prisms, melting at 28° and
boiling at 196°. Boiled with dilute sulphuric acid it breaks up into 3 molecules
of acetone (mesityl oxide appears as an intermediate product). With bromine it
forms a tetrabromide, fusing at 86°.

Acetone condenses to mesityl oxide and phorone in the same manner that acet-
aldehyde becomes crotonaldehyde (p. 194). Their structure probably agrees with
the formulas (compare Berichte, 14, 253) : —

^S^Xc = CH.CO. CH, and SS»(^ ^CO.

Mesityl Oxide. CHj/ ~

Phorone.

Both mesityl oxide and phorone unite with hydroxylamine, yielding corres-
ponding acetoximes (Berichte, 16, 494).

Mesitylene,CgYi.-^^, is produced when acetone is distilled with concentrated
sulphuric acid : —

3C3H,0 = CeH,,+3H,0.

This is a derivative of benzene (see this). It is also produced from mesityl
oxide and phorone, through the action of sulphuric acid, but if phorone be heated
with PjOj, pseudo-cumene is obtained. Other ketones, when acted upon with
sulphuric acid, also yield analogous benzene derivatives.

Acetone Bases. — ^When ammonia acts on acetone a condensation of two and
three molecules occurs, giving rise to the bases : Diacetonamine and Tri-
acetonamine : —

aCjH.O + NH3 = CeHijNO + H,0.

Diacetonamine.

3C3H,0 + NH, = C,H„NO + lU^O.
Triacetonamine.

Diacetonamine is a colorless liquid, not very soluble in water. When dis-
tilled it decomposes into mesityl oxide and NH3 ; conversely mesityl oxide and
NHj combine to form diacetonamine. It acts strongly alkaline and is an amide
base, forming crystalline salts with one equivalent of acid. If potassium nitrite
be allowed to act on the HCl-salt diacetone alcohol, (CHg)jC(OH).CHj.CO.CH3,
results; this loses water and becomes mesityl oxide.

Triacetonamine crystallizes in anhydrous needles, melting at 39.6°. With one
molecule of water it forms large quadratic plates, fusing at 58°. It is an imide

ACETONE HOMOLOGUES.

209

base (p. 167) with feeble alkaline reaction; potassium nitrite converts its HCl salt
into the nitrosoamine compound, C9Hie(NO)NO, which fuses at 73° and passes
into phorone when boiled with caustic soda. Hydrochloric acid regenerates tri-
acetonamine from the nitroso-derivative.

Diacetonamine and triacetonamine are intimately related to mesityl oxide and
phorone- (p. 208) ; their structure probably corresponds to the formulas :—

CH NH, »> X'

yc( and NH CO.

CHj/ ^CHj.CO.CHj \ /

Diacetonamine. (CH3)2C— CH,

Triacetonamine.

By the oxidation of diacetonamine with a chromic acid mixture (p. 203) we
get amido-isobutyric acid, (CH3)jC(NH2).C02H, and amido-isovaleric acid,
(CHj)j.C(NH2).CHj.C02H. By the addition of 2H to triacetonamine, converting
the CO group into CH.OH, there results an alkamine, CjH^NO, which may be
viewed as tetramsthyl oxypiperidine. By the abstraction of water from this the
base CjHijN, triacetonine, results. This approaches tropidine, CoHiaN, very
closely (^cnVA/f, 16, 2236; 17, 1788).

ACETONE HOMOLOGUES.

Methyl- ethyl Ketone, (P^^Xco = C^HjO, is formed :—

1. By oxidation of secondary butyl alcohol (p. 129).

2. By action of zinc ethide on acetyl chloride or zinc methyl upon propionyl

chloride.

3. By distillation of a mixture of calcium propionate and acetate.

4. By oxidation of methyl-ethyl oxyacetic acid and from methyl aceto-acetic ester

(see this).

Methyl-ethyl ketone is an agreeably smelling liquid, having a specific gravity
of 0.812 at 13°, and boiling at 81°. It combines with the primary sulphites.
When oxidized with chromic acid it yields two molecules of acetic acid. Its
acetoxime, CH3.C(N.OH).CjH5 (p. 205), is liquid and boils at 153°. The iso.
nitroso compound, CH3.CO.C{N.OH).CH3, isonitroso-methyl acetone, crystallizes
in pearly tables, melting at 74°, and boiling at 185°. It is converted into diaceiyl,
CH3.CO.CO.CH3, by the replacement of the N.OH-group. Dimethyl, glyoxime,
CH3.C(N.OH).C(N.OH).CHs (p. 207) consists of colorless crystals, which melt
on rapid heating.

Ketones, CgHijO:—

QHjXp^ CHjX-ifv CH3\p,Q

c,H x^" c,H,/^" an,/^"-

Diethyl Ketone. Metllyl-propyl Ketone. Methyl-isopropyl Ketone,
B, P. 101°, B, P. 103O. B, P. 96°,

These are produced according to the methods generally employed for making the
ketones. When boiled with a chromic-acid mixture, they decompose according to
the rules of oxidation (p. 203), and also otherwise exhibit all the usual ketone
reactions.

Diethyl Ketone, called Propione, because obtained by the distillation of cal-
18

2IO ORGANIC CHEMISTRY.

cium propionate, is obtained from carbon monoxide and potassium ethylate (p.
187). It is distinguished from the two methyl propyl ketones by not yielding
compounds with the primary alkaline sulphites. Amyl nitrite converts it into
isonitroso-diethyl-ketone, CH3.CH2.CO.C(N.OH).CH3 {Berichte, 22, 528).
Mention may here be made of the following higher ketones : —

Methyl-tertiary Butyl Ketone, C^^f) = ^h°/*^°' ^''^ *^ tertiary
butyl group (CH3)3C, called Pinacoline, is obtained from the hexylene glycol
termed pinacone, on warming with hydrochloric or dilute sulphuric acid (p. 202) ;
also by the action of zinc methyl on trimethyl acetyl chloride. It boils at 106°.
Its specific gravity at 0° is 0.823. When oxidized with chromic acid it decom-
poses into acetic and trimethyl acetic acids. Nascent hydrogen converts it into
pinacolyl alcohol (p. 129).

Dipropyl Ketone, C,H„0 = (C3H,)2CO, Butyrone, is the principal product
of the distillation of calcium butyrate. It boils at 144°, and at 20° has a specific
gravity equal to 0.8200. A chromic acid mixture changes it to butyric and
propionic acids. (-.jr >

Methyl Hexyl Ketone, /-■ w ' ^CO, Methyl cenanthol, is formed by the

oxidation of the corresponding octyl alcohol, and the distillation of calcium cenau-
thylate and acetate. It boils at 171° ; sp. gr. 0.818. It yields ^etic and caproic
acids when oxidized. ^tt v

Methyl-nonyl Ketone, C,,H,,0 ^ p „ ' ];,CO, is the chief constituent

of -oil of rue (from Ruta graveolens) ; it may be extracted from this by shaking
with primary sodium sulphite. It is produced in the distillation of calcium
caprate with calcium acetate. It is a bluish, fluorescent oil, which on cooling
solidifies to plates, melting at -|- 13°, and boiling at 225°. When oxidized it yields
acetic and pelargonic (CgHjgO^) acids.

The following additional ketones have been obtained by distilling the barium
salts of fatty acids with barium acetate (Berichte, 15, 1 7 10) : —

CjjHjjO = CjjHjj.CO.CHj from undecylic acid.

.bO =

«.CO.CH, "

QsHsoO = Ci3Hj,.CO.CH3
QieHsjO = C14Hjg.CO.CH3
CwHjjO = C15H31.CO.CH3

: C15H33.CO.CH3

' CijHgj.CO.CHj

lauric
tridecylic "
myristic "
pentadecatoic acid,
palmitic acid,
margaric "
stearic "

21°
28°
34°
39°
43°
48°

52°

SS-5°

When the salts of the higher fatty acids are distilled alone (p. 187) the simple
ketones (with two similar alkyls) result : —

(C,H„)jCO

(c,h:

IV^UXljj
to3„2I^2'

ilco

CO

caprone from caproic acid.

I

• 14.6

oenanthone " oenanthylic acid.

30°

caprylone " caprylic. "

.ii

40°

nonone " nonoic' "

58°

laurone " lauric "

(£1 ■

69°

myristone " myristic "

^

76°

palmitone " palmitic "

•r!

83°

stearone " stearic "

1

88°

^5^3o9 '

C35H,„0=(C„H35),CO

The corresponding paraffins are obtained when these ketones are reduced (see
p. 76).

MONOBASIC ACIDS. 211

MONOBASIC ACIDS.

The organic acids are characterized by the atomic group, CO.
OH, called carboxyl. The hydrogen of this can be replaced by
metals, forming salts (see p. 115). These organic acids may be
compared to the analogously constituted sulphonic acids, containing
the sulpho-group, SOj.OH.

The number of carboxyl groups present in them determines their
basicity, and distinguishes them as mono-, di-, tri-basic, etc., or as
mono-, di- and tri-carboxylic acids: —

CH,.CO,H CH /^g^g CjH.-Co'h

Acetic Acid. Malonic Add. „. ^Vy?.'

Monobasic. Dibasic. Tncarballylic Acid.

Tnbasic.

We can view the monobasic saturated acids as combinations of
the carboxyl group with alcohol radicals; they are ordinarily
\x.va\&A fatty acids. The unsaturated acids of the acrylic acid and
propiolic acid series, corresponding to the unsaturated alcohols, are
derived from the fatty acids by the exit of two and four hydrogen
atoms.

The most important and general methods of obtaining the
monobasic acids are : —

1. Oxidation of the primary alcohols and aldehydes: —

CH3.CH2.OH -f O2 = CH3.CO.OH -I- HjO,

Ethyl Alcohol. Acetic Acid.

CH-.COH + O = CH3.CO.OH.

Aldehyde. Acetic Acid.

2. The transformation of the cyanides of the alcohol radicals
(the so-called nitriles), by heating them with alkalies or dilute
mineral acids. The cyanogen group changes to the carboxyl group,
while the nitrogen separates as ammonia : —

CH..CN + 2H„0 H-HCl = CH3.CO2H -l-NH^Cl and
CH3.CN -j- H,0 -l-KOH = CHj.CO.K -)-NH,.

The change of the nitriles to acids is, in many instances, most advantageously
executed by digesting the former with sulphuric acid (diluted with an equal
volume of water) ; the fatty acid will then appear as an oil upon the top of the
solution. (Berichte, 10, 262.)

To convert the nitriles directly into esters of the acids, dissolve them in alco-
hol, and conduct HCI injo this solution, or warm the same with sulphuric acid.
{BeHchte, 9, 1590.)

3. Action of carbtjn dioxide upon sodium alkyls ^see p. 170) : —

CjHsNa -I- CO2 = CjHj.COjNa.

4. Action of carbon monoxide upon the sodium alcoholates heated to l6o°-200°.

CjHj.ONa -f. CO = C^Hs.COjNa.
Sodium Ethylate. Sodium Propionate.

il^ ORGANIC G&EMISTRY.

Fonnic acid results when the. caustic alkalies are employed : —

HONa + CO = H.COjNa.

Sodium Formate,

Usually, the rfeaction is very incomplete, and is often accompanied by secondary
reactions, resulting in the formation of higher acids. (Annalen, 2oa, 294.)

5. By the action of phosgene gas upon the zinc alky Is. At first

acid chlorides are formed, but they subsequently yield acids with

water :^—

Zn(CH3)2 + 2C0Clj = 2CH5.COCI + ZnClj, and
Acetyl Chloride.

CHj.CO.Cl + HjO = CH3.CO.OH + HGl.
Acetic Acid.

6. The following is a very interesting and a commonly applied method for the
synthesis of the fatty acids. By the action of sodium upon acetic esters, the
so-called aceto-acetic esters are produced, in which, by the aid of sodium and alkyl
iodides, one and two hydrogen atoms can be replaced by alkyls (R) (see acelb-
acetic esters) : —

CH,CO.CH,.CO.O.CA yields { ^g-^C.-ggliS^O^q'a?' '"'

Sodium alcoholate decomposes these alkylic esters (or alkyl ketonic acids) in
such a manner, that the group CH3.CO splits off and the fatty acid esters are pro-
duced, but are at once saponified, yielding salts : —

CH3.CO.CH(R).CO.O.CjH5 yields CH2(R).CO.OH
CH3.CO.C(Rj).CO.O.CjH5 " CH(R,).CO.OH.

We may r^ard the acids thus obtained as the direct derivatives of acetic acid,
CH3.CO.OH, in which one and two hydrogen atoms of the CHj group are replaced
by alkyls ; hence, the designations, methyl and dimethyl acetic acid, etc. : —

CH,.CH3 CHj.CjHs CH(CH3),

CO.OH CO.OH CO.OH.

Methyl Acetic Acid Ethyl Acetic Acid Dimethyl Acetic Acid

or Propionic Acid. or Butyric Acid. or Isobutyric Acid.

Very many fatty acids have been prepared in the above way (first by Frankland
and Duppa).

7. From the dicarboxylic acids, in which the two carboxyl groups
are in union with the same carbon atom. On the application of
heat, these sustain a loss of carbon dioxide : —

^'"^XCo'h = CHj.CO.H + CO^.

Malonic Acid. Acetic Acid.

In malonic acid, as in aceto-acetic acid (its esters, see above), the hydrogen
atoms of the group CHj may be replaced by alkyls; the resulting alkylic malonic
acids, when heated, sustain a loss of carbon dioxide, and form alkylic acetic acids.
{BeHchle, 13, 595.)

MONOBASIC ACIDS. 2 1 3

The isomerisms of the monobasic acids are influenced by the
isomerisms of the hydrocarbon radicals, to which the carboxyl
group is attached. There are no possible isomerides of the first
three members of the series C^HjoOa : —

HCO2H CH3.CO2H C2H5.CO2H.

Formic Acid. Acetic Acid. Propionic Acid.

Two Structural cases are possible for the fourth member, CiHgOj :
CHj.CHj.CHj.COjH and (CH,)2.CH.C02H.

Butyric Acid. Isobutyric Acid.

Four isomerides are possible with the fifth member, C5H10O2 =
C^Hj.COjH, inasmuch as there are four butyl, C4H9, groups, etc.

The hydrogen of carboxyl replaced by metals yields salts, and
when replaced by alkyls, compound ethers or esters are formed
(see p. 146).

CHs.CO.OH + KOH = CHj.COjK + H^O.

Potassium Acetate.

CH3.CO.OH + CjHj.OH = CH3.CO.O.C2H5 + HjO.

Ethyl Acetic Ester.

The residues combined in the acids with hydrogen are termed
aeid radicals : —

CH3.C0— CH3.CH2.CO— CH3.CH2.CH2.CO—

Acetyl. Propionyl. Butyryl.

These are capable of entering various combinations. Their halo-
gen derivatives, or the haloid anhydrides of the acids, like

CH3.CO.CI CH3.CHj.CO.Cl.

Acetyl Chloride. Propionyl Chloride.

are produced when the halogen derivatives of phosphorus act upon
the acids or their salts (p. 92) : —

CH3.CO.OH + PCI5 = CH3.CO.CI + PCI3O + HCl.

The aldehydes are the hydrides of these acid radicals, and the
ketones their compounds with alcohol radicals : —

CH3.CO.H CH3.COCH3.

Acetaldehyde. Acetone.

The conversion of the acids into aldehydes and ketones has
already received attention (pp. 188 and 200).

When an atom of oxygen unites two acid radicals we obtain
oxides of the latter, or the acid anhydrides : —

214 ORGANIC CHEMISTRY.

CjHjO.Cl + C2H30.0K=^2^3g\o + KCl.

Acetyl Chloride; Pbtassium Acetic

Acetate. Anhydride.

The amides of the acids appear by the union of the acid radicals
with the amide group : —

C2H3O.CI + NH3 = CjHjO.NHj, + HCI.

Acetamide.

Sulphur Compounds, corresponding to the acids and their anhy-
drides, exist: —

CjHjU.bU CjH.O/^-

Thioacetic Acid. Acetyl Sulphide.

Furthermore, substituted acids are obtained by the direct substi-
tution of halogens for the hydrogen of the alkyls present in the
acids : —

CHjCl.COjH CCI3.CO3H.

Monochlor-acetic Acid. Trichlor-acetic Acid.

The Jluorine derivatives (their esters) appear to form when HFl acts upon the
esters of the diazo-fatty acids (see these) : CN^HCO^H + HFl = CHjFl.COjH

The nitro-derivatives of the fatty acids are prepared by treating some of the
iod acids with silver nitrite (see Nitropropionic acid), or by the action of nitric
acid upon the fatty acids containing a tertiary CH-group {Berickte, 15, 2318).

Isonitroso-derivatives are obtained from the Icetone acids by the action of hy-
droxylamine (p. 203) ; —

CH3.CO.COjH -I- HjN.OH = CH3.C(N.OH).C02H + H^O.
Acetyl-carboxylic Acid. a-Isonitroso-propionic Acid.

In the same manner the /3-isonitroso-acids are produced from the aceto-acetic
esters (and their alkyl derivatives) by means of HjN.OH and saponification with
alkalies (Berichte, 16, 2996) : —

CH3.CO.CH2.CO2R yields CH3.C(N.OH).CH2.C02H.
Aceto-acetic Ester. . ^-Isonitroso-butyric Acid.

Alcoholic sodium and NaNOj acting on the monoalkylic aceto-acetic esters, pro-
duce the a-isonitroso-acids {BericAte, 15, 1057 ; 16, 2180) : —

CH3.CO.CHR.CO2R yields R.C(N.OH).COjH.

By reduction with tin and hydrochloric acid these derivatives become amido-
acids. They do not give the nitroso-reaclion with phenol and sulphuric acid
(p. 107).

Of the decomposition reactions of the acids those may be men-
tioned again which lead to the formation of hydrocarbons.

I. The distillation of the alkali salts with alkalies or lime (see
p. 71):—

CHj.eOjK + KOH = CH^ -f COsKj.

FATTY ACIDS.

215

2. The electrolysis of the alkali salts in concentrated aqueous
solution ; hydrogen separates upon the negative pole, and carbon
dioxide and the hydrocarbon upon the positive (see p. 71) : —

2CH3.CO2K + H^'O = C,H, + CO3K, + CO, + H3.

It may not be amiss here to direct attention to the successive reduction of the
higher into lower fatty acids. It serves as an excellent mode of preparing the
latter. To this end the acid is first converted into its amide, and this, by the reac-
tion of Hofmann (p. 159) (action of Br and NaOH), is changed into the next
lower amine. The further action of bromine and sodium hydroxide changes the
amine into a nitrile, and the latter is then readily converted into the corresponding
acid-amide; from which again by the further action of Br and NaOH the next
lower amine results {Berichie, 19, 1433) : —

^14^28^2 ^13^2?

.CO.NH, C,,H,,NH,

Myristic Acid. Myristic Amide. " TrlJecy'lamine."

C12H2.CN
Tridecyl Nitrile.

Ci,H„.CO.NH„etc.

Tridecylamide.

I. FATTY ACIDS, CnH^nOj.

Formic Acid

CHA =HCO,H

Acetic "

QHA = CH3.CO2H

Propionic "

CsHeO, = C,H5.C03

Butyric "

CHsOj = CaH^.CO^H

Valeric "

C5H10O2 = CiHg.COjH

Caproic "

C6H12O2 = CsHii.COjH

CEnanthylic "

C7H14O2 = CeHis.COjH

Caprylic

Acid CgHijOj +i6°*

Pelargonic Acid CgHijO^ +

12°

Capric

" CioHmO^ 31-4°

Undecylic " CuH^jOj

28°

Laurie

« Ci,H,A 43-6°

Tridecylic " CuH^jO,

40.5°

Myristic

" CiiH,A 54°

Pentadecatoic " CijHgjOj

51°

Palmitic

« QsHjA 62°

Margaric " C^t'^u'^.i

60°

Stearic

" q^H^A 69°

Nondecylic " C19H35O2

655°

Arachidic

« C,„H^,02 75°

Medullic " CjiH^Oj

72°

Behenic

" C,,H«0, 73°

- " C,,H„0,

—

Lignoceric

" CyH^Oj 80.5°

Hysenic " C^s,i^^O^

77°

Cerotic Acid

C„H„0, 79°

Melissic "

CaoHjoO, 91°

The acids of this series are known as the fatty acids, because their
higher members occur in the natural fats, and the free acids (ex-
cepting the first members) resemble fats. The latter are ester-like

* Melting points.

2l6 ORGANIC CHEMISTRY.

compounds of the fatty acids, and are chiefly esters of the trihydric
glycerol. On boiling them with caustic potash or soda (saponifica-
tion) alkali salts of the fatty acids are formed, and from these the
mineral acids release the fatty acids.

The lower acids (with exception of the first members) are oily
liquids; the higher, commencing with capric acid, are solids at
ordinary temperatures. The first can be distilled without decom-
position ; the latter are partially decomposed, and can only be dis-
tilled without alteration in vacuo. All of them are readily volatil-
ized with steam. Acids of like structure show an increase in their
boiling temperatures of about 19° for every -j-CHj. It may be
remarked, in reference to the melting points, that these are higher
in acids of normal structure, containing an even number of carbon
atoms, than in the case of those having an odd number of carbon
atoms (see above). The dibasic acids exhibit the same characteristic.
As the oxygen content diminishes, the specific gravities of the acids
grow successively less, and the acids themselves at the same time
approach the hydrocarbons. The lower members are readily solu-
ble in water. The solubility in the latter regularly diminishes with
increasing molecular weight. All are easily soluble in alcohol, and
especially so in ether. Their solutions redden blue litmus. Their
acidity diminishes with increasing molecular weight; this is very
forcibly expressed by the diminution of the heat of neutralization,
and the initial velocity in the etherification of the acids.

A mixture of the volatile acids can be separated by fractionation only with great
difficulty. It is advisable to combine this with & partial saturation. For instance,
a mixture of two acids, 1?.^., butyric and valeric acids, is about half saturated with
potash, and the aqueous solution distilled as long as the distillate continues to re-
act acid. If enough alkali had been added to saturate the less volatile acid (in
this case valeric), the more volatile compound (butyric acid) will be almost the
sole constituent of the distillate. Should the contrary be the real condition, the
distillate is subjected again to the same operation. The residue after distillation
is a mixture of salts of both acjds. This is true when the quantity of alkali was
more than sufficient for the saturation of the less volatile acid (valeric). The acids
are liberated from their salts by distillation with sulphuric acid, and the distillate
again submitted to the process described above.

To be assured of the purity of the acids, the aqueous solution of their alkali salts
is fractionally precipitated with silver nitrate. The less soluble silver salts (of the
higher acids) are the first to separate out.

(i) Formic Acid, CHA = HCO.OH.

Formic acid (^Acidum formicum) is found free in ants, in stinging
nettles, in shoots of the pine, in various animal secretions, and may
be obtained from these substances by distilling them with water. It
is produced artificially according to the usual methods (p. 211) : by

FATTY ACIDS.

217

the oxidation of methyl alcohol ; by heating hydrocyanic acid with
alkalies or acids : —

HCN + 2HjO = HCO.OH + NH,;

and on boiling chloroform with alcoholic potash : —

CHCI3 + 4KOH = HCO.OK + 3KCI + zRfi.

Worthy of mention, is the direct production of formates by the
action of CO upon concentrated potash at 100°. The reaction
occurs more easily if soda-lime at zoo°-22o° {jBertchie, 13, 718)
be employed : —

CO + NaOH = HCO.ONa ;

also by letting moist carbon dioxide act upon potassium : —

3CO2 + 4K + HjO = 2HCO.OK + COaKjj

potassium carbonate is produced at the same time.

Formates are also formed in the action of sodium amalgam upon a concentrated
aqueous ammonium carbonate solution, or with the same reagent upon aqueous
primary carbonates :— CO5KH -f H^ = HCOjK + H^O ; likewise on boiling
zinc carbonate with caustic potash and zinc dust. In all these methods it is the
nascent hydrogen which, in presence of the alkali, unites itself to carbon
dioxide ; —

COj + 2H + KOH = HCO.OK -f- HjO.

The most practical method of preparing formic acid consists in
heating oxalic acid : —

CPjHj = HCO.OH + CO2.

This decomposition is accelerated by the presence of glycerol, be-j
cause free oxalic acid sublimes with partial decomposition : — /

Crystallized oxalic acid (CgO^H, -\- zHjO) is added to moist concentrated
glycerol and the whole heated to 100-110°. Carbon dioxide is evolved and
formic acid distils over. As soon as COj ceases generating, add more oxalic
acid and heat anew, when a concentrated formic acid passes over. Continued
addition of oxalic' acid and the application of beat furnish a regular 56 per cent,
aqueous formic acid. The mechanism of the reaction is this : on heating crys-
tallized oxalic acid it parts with its water of crystallization and imites with the
glycerol to form glycerol formic ester (see p. 135) : —

fOH fOH

CaHJoH-t-C.O^H, =C3hJoH -f CO, + H,0.
{ OH (. O.COH

On further addition of oxalic acid the latter again breaks up into anhydrous
acid and water, which converts the glycerol formic ester into glycerol and
forpiic acid : —

C3H5(OH)2.(O.CHO) + HjO = C3Hj(OH)3 -f CHO.OH,-

2l8 ORGANIC CHEMISTRY.

The anhydrous oxalic acid unites anew with the regenerated glycerol to produce
the formic ester. The quantities of acid and water distilling over in the latter
part of the operation correspond to the equation : —

C.H^O, + 2H,0 = CH,0, + CO3 + 2H,0.

To obtain anhydrous acid, the aqueous product is boiled with PbO and the
beautifully crystallized lead salt decomposed, at 100°, in a current of hydrogen
sulphide. If anhydrous acid be employed in the reaction a 95-98 per cent,
formic acid can be immediately obtained. Boron trioxide will completely dehy-
drate this {^Berichte, 14, 1709).

Anhydrous formic acid is a mobile liquid, with a specific gravity
of 1.223 at 0° and boils at 99°. It becomes crystalline at 0°, and
fuses at +8.6°. It has a pungent odor (from ants) and causes
blisters on the skin. It mixes in all proportions with water, alco-
hol and ether, and yields the hydrate 2CH2O2 + H^O, which boils
at 105° and dissociates into formic acid and water. Concentrated,
hot sulphuric acid decomposes formic acid into carbon monoxide
and water: — CH2O2 = CO + HjO. A temperature of 160° suf-.
fices to break up the acid into carbon dioxide and hydrogen. The
same change may occur at ordinary temperatures by the action of
pulverulent rhodium^ iridium and ruthenium, but less readily
when platinum sponge is employed.

According to its structure, HCO.OH, formic acid is also an alde-
hyde, as it contains the group CHO ; this would account for its
reducing property, its ability to precipitate silver from a hot neu-
tral solution of silver nitrate, and mercury from mercuric nitrate,
the acid itself oxidizing to carbon dioxide.

The formates, excepting^ the sparingly soluble lead and silver salts, are readily
soluble in water.

The alkali salts deliquesce in the air; heated carefully to 250° they become
oxalates : — ^

CO.OK
2CHO.OK =1 + Hj.

CO.OK

By strong ignition of the resulting oxalate with an excess of alkali it decom-
poses with the formation of a carbonate and the liberation of hydrogen. These
reactions serve for the preparation of pure hydrogen. The ammonium salt,
CHO.O.NH4, decomposes into hydrogen cyanide and water when heated
to 180°:—

CH02.NH^= CNH + 2HjO.

The lead salt, (CH02)2Pb, crystallizes in brilliant needles, soluble in 36 parts of
cold water. The silver salt, CHOjAg, is obtained by the double decomposition
of the alkali salt with silver nitrate. It is precipitated in the form of white needles
that rapidly blacken on exposure to light. When heated, it decomposes into sil-
ver, carbon dioxide and formic acid : —

2CHO2 Ag = 2Ag -1- CO2 + H.qOjH.
The mercury salt sustains a similar decomposition.

FATTY ACIDS.

219

Monochlorformic acid, CCIO.OH, is regarded as chlor-carbonic acid.

(2) Acetic Acid, QH40, = CHs.CO.H.

This acid {Acidum aceticum) is produced in the decay of many
organic substances and in the dry distillation of wood, sugar, tar-
taric acid, and other compounds. It may be synthetically prepared :

1. By the action of carbon dioxide upon sodium methyl : — •

CH3.Na + COj = CHj.COjNa;

2. By heating sodium methylate with carbon monoxide to 100° : —

CHj.ONa + CO = CHj.COaNa;

3. By boiling methyl cyanide (acetonitrile) with alkalies or acids
(p. 211):—

CH3.CN + 2H20 = CH3.C02H + NH3.

It is made on a large scale by the oxidation of ethyl alcohol, and
by the distillation of wood.

( 1 ) In the presence of platinum sponge, the oxygen of the air converts ethyl alco-
hol into acetic acid; this occurs, too, in the acetic fermentation induced by a minute
organism (^Mycoderma aceti). The process is applied technically in the manufac-
ture of vinegar (p. 220). Dilute aqueous solutions of whiskey, wine or starch mash
are mixed with vinegar and yeast, and exposed to the air at a temperature of
20-40°. To hasten the oxidation, proceed as follows : Large, wooden tubs are
filled with shavings previously moistened with vinegar, then the diluted (10 per
cent.) alcoholic solutions are poured upon these. The lower part of the tub is
provided with a sieve-like bottom, and all about it are holes permitting the
entrance of air to the interior. The liquid collecting on the bottom is run
through the same process two or three times, to insure the conversion of all the
alcohol into acetic acid. It is very evident that this process is based on accelerated
oxidation, due to the increased exposure of the liquid surface to the air.

Pasteur contends that the presence of porous substances (wood shavings) is not
required in the vinegar manufacture, all that is necessary being the exposure of
the alcoholic fluid, mixed with Mycoderma aceti, to the air. (French or Orleans
Method.)

(2) Considerable quantities of acetic acid are also obtained by the dry distillation
of wood in cast-iron retorts. The aqueous distillate, consisting of acetic acid,
wood spirit, acetone, and empyreumatic oils, is neutralized with soda, evaporated
to dryness, and the residual sodium salt heated 230°-25o°. In this manner, the
greater portion of the various organic admixtures is destroyed, sodium acetate
remaining unaltered. The salt purified in this way is distilled with sulphuric
acid when acetic acid is set free and purified by further distillation over potassium
chromate.

"Anhydrous acetic acid at low temperatures consists of a leafy,
crystalline mass, fusing at 16.7°, and forming at the same time a
penetrating, acid-smelling liquid, of specific gravity 1.0514 at 20°.
It boils at 118°, and mixes with water in all proportions. In this
case, a contraction first ensues, consequently the specific gravity

220 ORGANIC CHEMISTRY.

increases until the composition of the solution corresponds to the
hydrate, QHA + H^O (== CH3.C(0H)s); the specific gravity
then equals 1.0754 at 15°. On further dilution, the specific gravity
becomes less, until a 50 per cent, solution possesses about the same
specific gravity as anhydrous acetic acid. Ordinary vinegar con-
tains about 5-15, per cent, acetic acid. Pure acetic acid should not
decolorize a drop of potassium permanganate.

Acetates. The acid combines with one equivalent of the bases,
forming readily soluble, crystalline salts. It also yields basic §alts
with lead and copper j these dissolve with difficulty in water. The
alkali salts have the additional property of combining with a mole-
cule of acetic acid, yielding acid salts, C2H3KO2 + C2H4O2. In
this respect, acetic acid behaves lilfe a dibasic acid. The fact that
it furnishes only neutral esters proves it, however, to be only mono-
basic. The existence of acid salts points to a condensation of two
molecules of the acid, analogous to that occurring with the alde-
hydes.

Potassium Acetate, C2H3KO^, deliquesces in the air, and dissolves readily in
alcohol. Carbon dioxide will set free acetic acid and precipitate potassium car-
bonate in such an alcoholic solution ; but in an aqueous solution, acetic acid will
displace carbon dioxide from the carbonates. On adding acetic acid to neutral
potassium acetate, an acid salt, CzHgKOj.CjH^Oj, crystallizes out on evapora-
tion ; this consists of pearly leaflets. It fuses at 148°, and at 200° decomposes
into the neutral salt and acetic acid.

Sodium Acetate, C2H3Na02 + sHjO, crystallizes in large, rhombic prisms,
soluble in 2.8 parts water at medium temperatures. Thp crystals effloresce on ex-
posure, and lose all their water. When heated, the anhydrous salt remains un-
changed at 310°.

Ammonium Acetate, C2Hj(NH^)02, is obtained as a crystalline mass on
saturating acetic acid with ammonia. 'When the aqueous solution is evaporated,
the salt decomposes into acetic acid and ammonia. Heat applied to the dry salt
converts it into water and acetamide, CjHj.O.NHj.

Ferrous Acetate, (C2H302)2Fe, is produced on dissolving iron in acetic acid;
it consists of green colored, readily soluble pi isms. The aqueous solution oxidizes
in the air to basic ferric acetate. Neutral ferric acetate, (C2H302)8Fe2, is not
crystallizable, and dissolves in water with a deep, reddish-brown color. On boil-
ing, ferric oxide is precipitated in the form of basic acetate. The same may be
said in regard to aluminium acetate.

Neutral Lead Acetate, (C2H302)2Pb -|- sHjO, is obtained by dissolving lith-
arge in acetic acid. The salt forms brilliant four-sided prisms, which effloresce
on exposure. It possesses a sweet taste (hence, called sugar of lead), and is
poisonous. When heated, it melts in its water of crystallization, loses all of the
latter at 100°, and at higher temperatures passes into acetone, CO2, and lead
oxide. If an aqueous solution of sugar of lead be boiled with litharge, basic
lead salts of varying lead content are produced. Their alkaline solutions find
application under the designation — lead vinegar. Solutions of basic lead acetates
absorb carbon dioxide from the air and deposit basic carbonates of lead — white lead.

Neutral Copper Acetate, (C2H30,),Cu -\- HjO, is obtained by the solution of
cupric oxide in acetic acid, and crystallizes in dark-green rhombic prisms. It is
easily soluble in water. Basic copptr salts occur in trade under the title of verdi-

SUBSTITUTION PRODUCTS OF ACETIC ACID. 23 1

^T"' rJ^^^ ^""^ obtained By dissolving cijpper strips in acetic acid in presence of
air. Tlie double salt of acetate and arsenite of copper is the so-called Schwein-
furt Green — mitis green.

Silver Acetate, C^HjOjAg, separates in brilliant needles pr leaflets when con-
centrated acetate solutions and silver nitrate are mixed. The salt is soluble in q8
parts water at 14° C.

SUBSTITUTION PRODUCTS OF ACETIC ACID.

The three hydrogen atoms of the methyl groUp in acetic acid can be replaced
by halogens. The chlorine derivatives result by the action of chlorine in the
sunlight Upon acetic acid, or if chlorine be conducted into a boiling aqueous solu-
tion of the acid containing iodine (compare p. 91). It is more practicable to
chlorinate acetyl chloride, CjHjO.Ci, and convert the product into the acids by
means of water. In this way a mixture of the mono-, di-, and tri-substituted acids
is always formed. They may be separated by fractional distillation. They are
more powerful acids than acetic. The monobalogen fatty acids can be obtained
from their corresponding oxy-fatty acids by the action of the haloid acids :
CH^OH.COjH + HBr = CHjBr.CO^H + H^O ; as well as from the diaM-
fatty acids (see these).

Monochloracetic Acid, CH3CI.CO2H (Preparation, Berichte, 17, 1286),
crystallizes in rhombic prisms or plates, fusing at 62°, and boiling at i85°-i87°.
The silver salt, CjHjClOjAg, crystallizes in pearly, glistening scales, and at 70°
decomposes into AgCl and glycolide. The ethyl ester, CjKjClOj.CjH^, obtained
by conducting HCl into a mixture of the acid and absolute alcohol, boils at 143.5°.

When monochloracetic acid is heated with alkalies or silver oxide, the chlorine
is replaced by the hydroxyl group and we get glycollic acid (C2H3(OH)02).
Amido-acetic acid, CH2(NH2).C02H, or glycocoU, results when the monochlor-
acid is digested with ammonia.

Dichloracetic Acid, CHCl^.COjH, is produced when chloral is heated with
CNK and some water : —

GClj.CHO + H2O + CNK = CHClj.COjH +KC1 + CNH,

and by the action of alkalies upon trichloracetic acid {^Berichte, 18, 757). It boils
from I90°-I9I°, and solidifies below 0°. The free acid is best obtained by heat-
ing its potassium salt (prepared from the ethyl ester) in a current of HCl gas.

The ethyl ester, C^HCljO.O.CjHj, is prepared by the action of potassium
cyanide and alcohol upon chloral. (For the mechanism of this peculiar reaction,
see Berichte, 10, 2120.) It is a heavy liquid, boiling from I56°-IS7°. Alcoholic
potash decomposes it immediately into potassium dichloracetate and alcohol. When
the acid is boiled with aqueous potash, it breaks up into oxalic and acetic acids.
The salts of the di-chlor acid reduce silver solutions, forming at first glyoxylic acid
(Berichte, 18, 227).

Trichloracetic Acid, CCl,.CO^H, is made by letting chlorine act in the sun-
light upon tetrachlorethylene, CjCl^. It is best obtained by the oxidation of
chloral with fuming nitric acid, chromic acid, potassium permanganate, or potas-
sium chlorate [Berichte, i8, 3336) : —

CCI3.COH -[- O = CClj.COjH.

It consists of rhombic crystals, which deliquesce, melt at 52°, and boil at 195°- It
yields easily soluble, crystalline salts with bases, but on evaporation they are soon
broken up. The ethyl ester, GjGljO.O.G^-Hj, boils at 164".

222 ORGANIC CHEMISTRY.

When the acid is heated with ammonia or alkalies it yields CHClj and carbon
dioxide: CClj.COjH = CCI3H + CO^. Sodium alcoholate changes it into
potassium carbonate and formate, and potassium chloride.

Nascent hydrogen (sodium amalgam) reconverts the substituted acetic acids into
the original acetic acid.

The bromine substitution acids result when anhydrous acetic acid is heated in
sealed tubes along with bromine.

The bromination is more readily effected (also in the case of the homologous
acids) in the presence of amorphous phosphorus (Hill). Then, under certain
circumstances, the reaction proceeds without pressure, and the monosubstituted
acids are the sole products (Volhard) (Berichte, 21, Ref. 5 ; 21, 1725 and 1904).

Monobromacetic Acid, CjHgBrOj (Preparation, see Berichte, 16, 2502),
crystallizes in deliquescent rhombohedra, and boils at 208°. Its ethyl ester, C^H,
BrOj.CjHj, is a liquid which boils at 159°, and suffers a slight decomposition at
the same time.

Dibromacetic Acid, CjHjBrjOj, is a crystalline mass, melting at 54-56°, and
boiling from 232-235°. Its salts are very unstable. The Ethyl ester, C^HBrjO.
O.CjHj, like that of the dichloracid, may be prepared from broraal with CNKand
alcohol. It boils at 192-194°.

Tribromacetic Acid, C2HBr302, made from tribromacetyl bromide, CBr,.
COBr, and by the oxidation of bromal with nitric acid, consists of table-like crys-
tals, permanent in the air. It melts at 135°, and boils at 245°.

The iodine substitution acids (their esters) are obtained from the chlor- and
brom-acid esters when the latter are heated with potassium iodide (p. 95). They
are also produced on boiling acetic acid anhydride with iodine and iodic acid
(p. 91).

Moniodacetic Acid, CjHjIOj, crystallizes in colorless plates, which melt at
82°, and decompose when more strongly heated. Its salts are unstable. The
ethyl ester boils at 178-180°. When heated with HI it passes into acetic acid (p.
91) : CHjLCOjj + HI = CHj.CO^H + I^:

Di-iodacetic Acid, CHIj.COjH. Its ethyl ester, first prepared from dibrom-
acetic acid ester and KI, may also be made by allowing iodine to act upon diazo-
acetic ester (see this). It is a heavy, bright-yellow colored oil. It is volatile with
steam, decomposes on heating, and when exposed to the air liberates iodine
rapidly.

Ethyl Nitroacetic Ester, CH2(NOj).C02.CjH5, is produced in the action of
silver nitrite upon bromacetic ester, and boils at 151-152° with scarcely any de-
composition. By reduction with tin and hydrochloric acid it yields amido-acetic
acid. The free nitro-acetic acid at once decomposes into nitromethane, CH..
(NO2), and COj.

Ethyl Isonitroso-acetic Ester, CH(N.OH).C02.(C2H5), or oximido-acetic
ester (p. 205), is produced by the action of nitric acid upon the aceto-acetic ester.
It is a yellow oil, which suffers decomposition when distilled {Annalen, 222, 48).

3. Propionic Acid, CsHgOj = CH3.CHj.CO2H, may be pre-
pared by the methods in general use in making fatty acids, and by
the oxidation of normal propyl alcohol with chromic acid, or froKi

SUBSTITUTION PRODUCTS OF ACETIC ACID. 223

ethyl cyanide. CsHs.CN (propio-nitrile) by the action of sulphuric
acid (p. 211). Especially noteworthy is its formation from acrylic
acid, CaHjOj, through the agency of nascent hydrogen (sodium
amalgam) ; likewise its production from lactic and glyceric acids
when these are heated with hydriodic acid : —

CHs.CH(OH).COjH + 2HI = CHj.CH^.COjH + H^O + t,.
Lactic Acid.

Propionic acid is a colorless liquid, of penetrating odor, with
specific gravity 0.992 at 18°, and boiling at 140°. Calcium chlo-
ride separates it from its aqueous solution, in the form of an oily
liquid.

The barium salt, (C3H502)jBa + H^O, crystallizes in rhombic prisms. The
silver salt, CjHjOjAg, consists of fine needles, soluble in 119 parts water at 17°.
Its ethyl ester boils at 98°.

Substitution Products. — By the replacement of one hydrogen
atom in propionic acid, two series of mono-derivatives, termed the
a- and /J-derivatives, arise : — *

a-Derivative. /3-Derivative.

The isomeric compounds of the higher fatty acids are similarly
designated as a-, /S-, y, etc.

Whenever bromine is introduced into the fatty acids, it occupies
preferably the a- position. In the formation of the halogen de-
rivatives from the unsaturated acids by addition of the halogen
hydride, the halogen enters in preference the /J- or ;'- position (see
Berichte, 22, Ref. 742) : —

CHjcCH.CO^H + HI = CHjI.CHj.COjH.

Acrylic Acid. i8-Iodpropionic Acid.

The a-halogen acids yield a-oxy-acids when heated with aqueous bases, whereas
the ;3-derivatives readily part with a halogen hydride, and become unsaturated
acids (Annalen, 219, 322) : —

CHaCl-CHj.COjH CHjiCH.CO^H + HCl.

Acrylic Acid.

From the y-acids originate salts of y-oxy-acids through the action of bases-
When in free condition they change to lactones. The alkaline carbonates imme-
diately convert them into the latter.

a-Chlorpropionic' Acid, C3H5CIO2, is obtained by the decomposing action of
water upon lactyl chloride (see lactic acid) : —

CH3.CHCI.COCI -f HjO = CH,.CHCl.CO.OH -f HCl.

2 24 ORGANIC CHEMISTRY.

It is a thick liquid, of specific gravity 1.28, and boils at 186°. When heated
with moist oxide of silver, it becomes a-lactic acid. The ethyl ester boils at 146°.
It is obtained by the action of alcohol upon lactyl chloride.

/3-Chlorpropionic Acid, CaH^ClO^, is ptodaced by the action of chlorine
water upon /3-iodpropionic acid, and the addition of HCl to acrylic acid :^

CH2:CH.C02H + HCl = CH^Cl.CH^.CO^H.

Also upon heating ^-oxypropionic acid (hydracrylic acid) to 120° with fuming
hydrochloric acid.

It is crystalline, and melts at 41.5°. The ethyl ester boils at 155° (162°).

a-Brompropionic Acid, CjHjBrO^, is produced by the direct bromination of
propionic acid in the presence of bromine {^Berichte, 22, 162), and when o-lactic
acid is treated with HBr. It is crystalline, melts at 24.5°, and boils near 202°.
The ethyl ester boils about 162°.

/?-Brompropionic Acid, CjHjBrOj, is formed when bromine water acts on
jS-iodpropionic acid, or by the addition of HBr to acrylic acid, and when hydracrylic
acid is heated with hydrobromic acid. The acid crystallizes, and melts at 61.5°.

(z-Iodpropionic Acid, CjHjIOj, is produced by acting on a lactic acid, with
phosphorus iodide. It is an oily liquid.

/3- lodpropionic Acid, C3H5IO2, forms when PI3 and water are allowed to
act on glyceric acid (Annalen, 191, 284) : —

CH2.0H.CH(OH).C02H + 3HI = CHjI.CH^.COjH + Ij + HjO,

and when HCl is added to acrylic "acid. Tg prepare it, treat crude glyceric acid
with iodine and phosphorus {Berichte, 21, 24). The acid crystallizes in large,
colorless, six-sided plates, with peculiar odor. They melt at 85°. Hot water dis-
solves the acid readily. Heated with concentrated hydriodic acid, it is reduced to
propionic acid. The ethyl ester boils at 202° [Berichte, 21, 97).

)3-NitrOpropionic Acid, CH2(N02).CH2.C02H. This is formed, like the
nitro-paraffins (p. 107), by the action of silver nitrite upon /3-iodpropionic acid.
It is very readily soluble in water, alcohol and ether. It crystallizes from chloro-
form in brilliant scales, melting at 66—67°. Reduced with tin and hydrochloric
acid it becomes /3amidopropionic acid. The ethyl ester, obtained from /3-iod-
propionic ester, boils from 161^165°.

a-Isonitroso-propionic Acid, CH3.C(N.OH).C02H, is a white, crystalline
powder, made from acetyl carboxylic acid and methyl aceto-acetic ester (p. 214). It
decomposes at 177° without fusitig. Reduction converts it into a- amidopropionic
acid (Alanine).

The ethyl ester consists of shining crystals, melting at 94°, and boiling at 233°.
It is also formed when nitrous acid acts upon isosuccinic ester (JBerichte, 20, S33)'

The disubstitution products of propionic acid may exist in three isomeric
forms ; —

CHj.CXj.COjH CHj.X.CHX.COjH CHX^.CHj.COjH.

a-Deri^ttves. a^ Derivatives. -^-Derivatives.

SUBSTITUTION PRODUCTS OF ACETIC ACID.

225

The derivatives of the homologous acids are similarly named. The a-deriva-
tives are almost the exclusive product in the chlorination and bromination of the
fatty acids or their derivatives. The addition of chlorine or bromine (best in
CSj solution) to the unsaturated acids converts them into 0,8-derivatives :—

CH^iCH.COjH + Br^ = CH2Br.CHBr.COj.H.

Boiling water scarcely affects the a-derivatives ; but the OjS-compounds become
halogen hydroxy-acids : —

CH2C1.CH(0H).C02H and CH2(0H).CHC1.C02H.

The alkalies convert these into anhydride or ether-acids (glycide acids).

a-Dichlorpropionic Acid, CHj.CCljj.COjI^ is obtained from dichlorpropio-
nitrile, CHj.CCl2.CN (by chlorination of propionitrile), with sulphuric acid (see
p. 211). The ethyl ester may be formed from pyroracemic acid, CHj.CO.COjH,
by the action of PCI 5 and the decomposition of the chloride produced at first
with alcohol. It is a liquid that boils at i85°-igo°, solidifies below 0°, and is
volatilized in a current of steam. The ethyl ester, CgHjCl^.Oa.CjHj, boils at
IS6°-IS7°; its chloride boils at 105°-! 15°, and the amide, CHj.CClj.CO.NH^,
melts at 116°.

When the aqueous solution of the a-dichlorpropionates are boiled, they sustain
decomposition. Zinc and sulphuric acid convert the acid into propionic acid.
The silver salt changes to CHj.CO.CO2H (pyroracemic acid), and o-dichlorpro-
pionic acid (see Berichte, 18, 1227). a-Chlcracrylic acid is produced on boiling
with alcoholic potash. Zinc and hydrochloric acid convert it into propionic acid.

a/3-Dichlorpropionic Acid, CHjCl.CHCl.CGjH, follows from the oxidation
of dichlorhydrin, CHjCl.CHCl.CH^.OH (from glycerol and allyl alcohol, p. 134),
also by heating a-chloracrylic acid (melting at 64°) to 100° with HCl {Berichte,
10, 1599), and by heating glyceric acid with hydrochloric acid (together with
chlorlactic acid, Berichte, 12, 178). If PCI5 be allowed to act upon glyceric
acid, the chloride, CHjCl.CHCl.COCI, forms, and this yields the ester of the
a^-acid when treated with alcohol. a/3-Dichlorpropionic acid crystallizes in fine
needles which melt at 50° and boil at 210°, suffering slight decomposition. The
ethyl ester boils at 184°.

/3-Dichlorpropionic Acid, CHCI2.CH2.CO2H, is produced by heating
/3-chloracrylic acid with hydrochloric acid. It melts at 56°, and is reconverted by
caustic potash into /3-chloracrylic acid {Berichte, 20, Ref. 415).

a-Dibrompropionic Acid, CHj.CBrj.COjH, is obtained by heating propionic
acid or abrompropionic acid with bromine {Berichte, 18, 235). It crystallizes in
quadratic tables, melting at 61°, and boils, with slight decomposition, at 220°.
The ethyl ester is a liquid with camphor-like odor, and boils at 190°. The salts
of the acid are tolerably stable. Zinc and sulphuric acid reduce it at once to pro-
pionic acid. Alcoholic potash changes it to a-bromacrylic acid, CHjtCBr.COjH,
and the latter combines with HBr and becomes a^S-dibrompropionic acid. When
the a-dibrom-acid is heated to 100°, with fuming HBr, it is transformed into an
isomeric aj3-dibrom-acid. It is very probable that a-bromacrylic acid forms at first
and then takes on HBr.

a^-Dibrompropionic Acid, CH2Br.CHBr.CO2H, is produced by oxidizing
dibromhydrin, CH2Br.CHBr.CH20H (dibromallyl alcohol, p. 134), and acrolein
dibromide (p. 199) with nitric acid; also by adding Br2 to acrylic acid and HBr
to o-bromacrylic acid. This compound is capable of existing in two allotropic
modifications, which can be readily converted one into the other. The one form
melts at 51°, the other, more stable, at 64°. The acid boils at 227°, with partial
decomposition. The ethyl ester has a fruit-like odor, and boils at 2II°-2I4°.

19

226 ORGANIC CHEMISTRY.

The salts are very stable. Zinc and sulphuric acid reduce the acid first to acrylic
acid. Potassium iodide effects the same. Alcoholic potash changes the acid to
a-bromacrylic acid. Brom-lactic acid is produced by digesting the silver salt with
water lyBerichte, i8, 236). The proiluct is glyceric acid if an excess of silver oxide
has been employed. •

4. Butyric Acids, CiHeOj.
Two isomeric acids are possible : —

CH3.CH2.CH2.CO2H ^^sXcH.CO^H.

Normal Butyric Acid. Isobutyric Acid.

(i) Normal Butyric^Acid, butyric acid of fermentation, oc-
curs free and also as the glycerol ester in the vegetable and animal
kingdoms, especially in the butter of cows. It exists as hexyl ester
in the oil of Heracleum giganteum, and as octyl ester in Pastinaca
saiiva. It is produced in the butyric fermentation of sugar, starch
and lactic acid, in the decay or oxidation of normal butyl alcohol,
and by the action of nascent hydrogen upon crotonic acid, QHjOj.
It is prepared synthetically from propyl cyanide (butyronitrile) on
boiling with alkalies or acids : —

C3H7.CN + 2H2O = CjHy.COjH + NH3 ;

also, from ethylic-aceto-ethyl acetate, and ethylmalonic acid (p.
212) ; hence the term ethyl acetic acid.

Ordinarily the acid is obtained by the fermentation of sugar or starch, induced
by the previous addition of decaying substances. According to Fitz, the butyric
fermentation of glycerol or starch is most advantageously evoked by the direct
addition of schizomycetes, especially butyl-bacillus and Bacillus subtilis (^Berichte,
". 49. S3)-

Butyric acid is a thick, rancid-smelling liquid, wliich solidifies
when cooled. It boils at 163°; its specific gravity equals 0.9587
at 20°. It dissolves readily in water and alcohol, and may be
thrown out of solution by salts. The ethyl ester boils at 1 20°.

The butyrates dissolve readily in water. The barium salt, {C^Yi^O^^a. -\-
SHjO, crystaUizes in pearly leaflets. The calcium salt, (C4H,02)2Ca + HjO
(Annalen, 213, 67), also yields brilliant leaflets, and is less soluble in hot than in
cold water (in 3.5 parts at 15°); therefore the latter grows turbid on warming.
Silver nitrate precipitates silver butyrate in shining needles from solutions of the
butyrates. It is soluble in 400 parts water at 14°.

The butyrates uoite to double salts with the acetates ; these behave like salts
of a butyro-acetic acid, C^HjOj.CjH^Oj. The free acid appears in the fer-
mentation of calcium tartrate ; when distilled, it breaks up into butyric and acetic
acids.

y-Chlorbutyric Acid, CH^Cl.CHj.CHj.CO^H, has been prepared from
7-chlortrimethylenecyanide. It solidifies in the cold and melts at 10°. When
distilled it yields HCl and 7-caprolactone (see this).

SUBSTITUTION PRODUCTS OF ACETIC ACID. 227

a^-Dichlorbutyric Acid, CHj.CHCl.CHCl.CO^H. This results upon the
addition of chlorine to crotonic acid. It melts at 63°. With KOH it forms
chlorisocrotonic acid {Berichte, 20, 1008).

Trichlorbutyric Acid, C4H5CL3O2, appears in the oxidation of trichlorbutyr-
aldehyde or alcohol (p. 197), in the cold, with concentrated nitric acid, or by
means of chlorine. It consists of needles, melting at 60° and soluble in 25 parts
of water. /3-Chlorcrotonic acid is formed when the trichloracid is boiled with
zinc and water: C4H5CIJO2 + Zn = CiHgClOa + ZnCl^.

Bromine converts butyric acid into a-Brombutyric Acid, CHgCHj.CHBr.
CO. OH, which boils about 215°. Alcoholic potash changes this to crotonic acid.
Its ethyl ester boils at 178°. With CNK the latter yields a-cyanbutyric ester,
boiling at 208°.

j8-Brombutyric Acid, CHj.CHBr.CH^.COg.H, is produced (together with a
little a-acid) on heating crotonic acid with hydrobromic acid. Crotonic acid com-
bines with bromine to form a/3-dibrombutyric acid, CHj.CHBr.CHBr.COjH,
which melts near 87°.

y-Brom- and lodobutyric acids result from butyrolactone (see this) by the
action of HBr and HI; the first melts at 33°, the second at 41° {Berichte, 19,
Ref. 165).

/3-Iod-butyric Acid is obtained by the union of crotonic acid and isocrotonic
acid with hydriodic acid ; it melts at 110° {Berichte, 22, Ref. 741).

a-Isonitroso-butyric Acid, C2H5.C(N.OH).C02H, obtained from ethylic
aceto-ethyl acetate (p. 214), consists of silky needles, melting with decomposition
at 152°. The ;3-Isonitroso Acid, CH3.C(N.OH).CH2C02H, from ethyl aceto-
acetic ester and hydroxylamine, melts with decomposition at 140°.

When a saturated solution of calcium butyrate is heated for some
time it slowly passes into calcium isobutyrate {Annalen, 181, 126).

C2) Isobutyric Acid, (CH3).i.CH.C02H, dimethyl-acetic acid,
is found free in carobs (^Ceratonia siliqua), as octyl ester in' the oil
of Pastinaca sativa, and as ethyl ester in croton oil. It is prepared
by oxidizing iso butyl alcohol, and from isopropyl cyanide : —

CjHj.CN + 2H2O = C3H,.C02H + NH3.

It is also obtained from dimethyl-aceto-acetic ester and from
dimethyl malonic acid (p. 212), therefore the name dimethyl acetic
acid.

Isobutyric acid bears great similarity to normal butyric acid, but
is not miscible with water, and boils at 155°- Its specific gravity
at 20° is 0.9490. It is soluble in 5 parts of water.

The calcium salt, (C4H,02)2Ca + sHjO, crystallizes in monoclinic prisms
and dissolves more readily in hot than in cold water. The silver salt, C^H^Oj Ag,
consists of shining leaflets soluble in 1 10 parts H^O at 16°. The ethyl ester boils
at 1 10° ; its specific gravity = 0.89 at 0°. Potassium permanganate oxidizes it to
a-oxyisobutyric acid.

a-Bromisobutyric Acid, (CH3)2.CBr.C02H, is produced when isobutyric
acid is heated with bromine to 140°. It crystallizes in white tables, melting at
48°, and boiling at i98°-200°. The ethyl ester boils at 163° (corr.) ; its sp.gr.
= I 328 at 0° ° Moist silver oxide or barium hydrate converts it into a oxyiso-
butyric acid, (CH3)2.C(OH),C02H. When boiled together with silver it yields
tetratnethyl succinic acid and grimethyl glutaric acid.

228 ORGANIC CHEMISTRY.

5. Valeric Acids, C5H10O2. There are four possible isomer-
ides : —

1^'"' CH/^|f= C(CH3),

\CH3
I " COjH COj

CO,H CO,H Methyl-ethyl Trlmethyl

I. CH, 2. CH2 3. I \''"« and 4. I

Propyl Acetic Acid. Isopropyl

Normal Valeric Acid. Acetic Acid.
Isovaleric Acid.

Acetic Acid. Acetic Acid.

(1) Normal Valeric Acid, CH3.(CH2)3.C02H, formed in the oxidation of
normal amyl alcohol and from butyl cyanides, is similar to butyric acid, but is more
sparingly soluble in water (l part in 27 parts at 16°). It boils at x86°. Its specific
gravity at 0° equals 0.9568. It congeals in the cold, and melts at — 20° [Berichte,
21, Ref. 649).

The a isonitroso-acid, C3Hj.C(N.OH).C02H, derived from propyl aceto-acetic
ester (p. 212), melts with decomposition at 144°. 'Vii&y isonitroso-acid, CW^.Q.
(N.OH).CH2.CH2.C02H, formed from Isevulinic acid and hydroxylamine, fuses
with decomposition at 96°, and when digested with sulphuric acid, passes into
imido-lactone {^Berichte, 20, 2671).

(2) Isovaleric Acid, (CH3)2.CH.CH2.C02H, isopropyl acetic
acid, or isobutyl carboxylic acid, is obtained from isobutyl cyanide,
CiHc,. CN, by saponification with alkalies, likewise from isopropyl
aceto-acetic ester, and from isopropyl-malonic ester (see p. 212).
It is an oily liquid with an odor resembling that of old cheese ;
possesses a specific gravity of 0.947, and boils at 174°. It is
optically inactive.

The isovalerates generally have a greasy touch. When thrown in small pieces
upon water they have a rotary motion, dissolving at the same time. The
barium salt, (C^^O^^dL, usually crystallizes in thin leaflets, and is soluble in
2 parts water at 18°. The calcium salt, (C5Hg02)2Ca + sHjO, forms rather
stable, readily soluble needles. The officinal zinc%aS\., (C5Hg02)2Zn + 2H2O,
crystallizes in large, brilliant leaflets; when the solution is boiled a basic salt
separates. The silver salt, CjHgOjAg, is very sparingly soluble in water (in 520
parts at 21°). The ethyl ester, C5Hg(C2H5)02, boils at 135°.

a-Brom-isffvaleric acid, C3H,.CBr.C02H, is formed in the bromination of iso-
valeric acid in the presence of phosphorus. It melts at 40° {Berichte, 21, Ref. 5).
Silver converts its ester into two dipropylsuccinic acids {^Berichte, 22, 48).

Potassium permanganate oxidizes isovaleric acid to /3-oxy isovaleric acid, (CHj)2.
C(OH).CH2.C02H. Nitric acid attacks in addition the CH-group, forming
methyloxysuccinic 'acid and ;3 nitroisovaleric acid, (CHg)2.C(N02).CH2.C02H,
which crystallizes in large leaflets and is sparinglj^ soluble in water; ^-dinitro-
propane, (CH3)2C(N02)2 (Berichte, 15, 2324), is produced at the same time.

Ordinary valeric acid occurs free, and as esters in the animal and
vegetable kingdom, chiefly in the small valerian root {^Valeriana
officinalis), and in the root of Angelica Archangelica, from which it
may be isolated by boiling with water or a soda solution. It is a
mixture of isovaleric acid with the optically active methyl-ethyl

SUBSTITUTION PRODUCTS OF ACETIC ACID. 229

acetic acid, and is therefore also active. A similar artificial mix-
ture may be obtained by oxidizing the amyl alcohol of fermentation
(p. 130) with a chromic acid solution. Inasmuch as the salts of
methyl-ethyl acetic acid dissolve with difficulty, it is a general
thing to obtain only isovalerates from the ordinary valeric acid.
Valeric acid combines with water and yields an officinal hydrate,
CjHioOj -f H2O, soluble in 26.5 parts of water at 15°.

(3) Methyl-ethyl Acetic Acid, ^^^aXcH.COjH (active valeric acid), Is

obtained by synthesis from methyl-ethyl- aceto-acetic ester, from methyl-ethyl-ma-

lonic ester (p. 212), and from the so-called methyl-ethyl oxalic acid, /^S'^^C

(OH).C02H (see this); also from methylcrotonic acid (p. 241), CsHjOj, by
addition of 2H (when heated with HI), and from brom- and iodmethyl ethyl
acetic acid (from methylcrotonic acid and angelic acid) by reduction with sodium
amalgam.

The acid possesses a valerian-like odor, boils at 175° and has a specific gravity
of 0.941 at 2i°- The calcium salt, (€511,02)203 -f SHjO, crystallizes in brilliant
needles which slowly effloresce in the air. The barium salt, {C^^O^^ Ba, is a
gummy amorphous mass, and is not crystallizable. The silver salt, C5H902Ag,
is much more soluble than that of the isovaleric acid (in 88 parts at 20°J and crys-
tallizes in groups of feather- shaped, shining needles.

The synthesized methyl-ethyl acetic acid is optically inactive. An active modi-
fication is present in the naturally occurring valeric acid, and is obtained by the
oxidation of the amyl alcohol of fermentation (see above). The silver salt affords
a means of separating it from the accompanying isovaleric acid (Annalen, 204,
159). The active acid has not yet been isolated in a pure condition; otherwise
it exhibits all the properties of the inactive i^ariety, and yields perfectly similar
salts.

(4) Trimethyl Acetic Acid, (CH3)3C.C02H (Pinalic acid), is formed from
tertiary butyl iodide, (0113)301 (p. 131), by means of the cyanide, also by the
oxidation of pinacoline (p. 210). It is a leafy, crystalline mass, melting at 35° and
boiling at 163°. The acid is soluble in 40 parts HjO at 20°, and has an odor
resembling that of acetic acid.

The barium salt, (C^ll^O^)^'^^ -f sHjO, and calcium salt, (CsHgO^jgCa -{-
5H2O, crystallize in needles or prisms. The silver salt, CjHgOjAg, is pre-
cipitated in glistening, flat needles. The ethyl ester, C^"R^O^.C^^, boils at
118.5°-

The Hexoic or Caproic Acids, CeHj^Oj = CsHn.COjH.

Eight isoraerides are theoretically possible (because there are
eight C5H11 (amyl) groups). Seven of these have been prepared.
We may mention : — *

(i) Normal Caproic Acid or Hexoic Acid, CH3(CH2)4.C02H, which is
produced in the fermentation of butyric acid, and may be obtained by the oxida-
tion of normal hexyl alcohol, and from normal amyl cyanide, C5Hj1.CN. In
addition, it forms when butyl iodide acts on aceto-acetic ester. It is an oily liquid
that has a sp. gr. of 0.928 at 20°, boils at 205°, solidifies in the cold and melts at
—2°. Its barium salt, {C^U.^-S:>^)^^a. -f 3H2O, is soluble in 9 parts of water
at 10°. The ethyl ester boils at 167°-

230 ORGANIC CHEMISTRY.

(2) Isobutyl Acetic Acid, (CH3)2.CH.CH2.C02H, is obtained from isoamyl
cyanideand from isobutyl aceto-acetic ester (p. 212). Some fats apparently contain
it. It has a specific gravity of 0.93 1 at 15° and boils at 200°. The ethyl ester\x>\\i
at 161°. By the oxidation of isobutyl acetic acid with potassium permanganate the
lactone of y-oxy-isocaproic acid, (CH3)2.C(OHf).CH2.CH2.C02H, is formed.

(3) Methylpropyl Acetic Acid, *^^^' ^CH.COaH, is prepared from niethyl-

propyl carbinol (p. 131) through the cyanide and from amethyl valerolactone
(from saccharin) by reduction with HI. It boils at 198° and has the specific
gravity 0.94.1 at 0° [Berichte, 16, 1832). The same acid has been obtained from
isosaccharin {Berichte, 18, 633).

Heptoic Acids, CyHi^O^ = CgHia.COjH.
Six of the seventeen possible isomerides are known.

(1) Normal Heptoic or CEnanthylic Acid, CH3(Cj,H5)5.C02H, is pro-
duced by the oxidation of oenanthol (p. 198) with nitric acid, and also from normal
hexyl cyanide, CgH13.CN. It is a fatty-smelling oil, boiling near 223°, and solid-
ifying, when cooled, to a crystalline mass, which melts at — 10.5°. The ethyl ester

boils at 188°. prr .

(2) Methyl-n-butyl Acetic Acid, J^'J^sXcH.COjH, obtained synthetically

from aceto-acetic ester, has been prepared by reducing Isevulocarboxylic acid. It
boils at 210° {^Berichte, ig, 224). C H \

(3) Ethyl-n-propyl Acetic Acid, r^-^ ^CH.COjH, from aceto-acetic ester,

boils at 209° {Berichte 19, 227).

The Octoic Acids, CgHijOj = C^Hu.COjH.

Normal Octoic or Caprylic Acid is present in fusel oil, and as glycerol ester
in many oils and fats. It is produced by the oxidation of fats and oleic acid
with nitric acid; also obtained from normal octyl alcohol. The acid crystallizes
in needles or leaflets, which melt at l6°-i7°, and boil at 236°-237°. The barium
salt is soluble in 50 parts boiling water, and crystaUizes in fatty tablets.

Nonoic Acid, CgHjgOj, Pelargonic Acid, occurs in the leaves of Pelargo-
nium roseum, and is prepared by the oxidation of oleic acid and oil of rue
(methyl nonyl ketone, p. 2lo), with nitric acid. It may also be obtained from
norma.] octyl cyanide, CgH17.CN, and by the fusion of undecylenic acid (p. 242)
with potassium hydroxide. It is, therefore, the normal nonoic acid. It fuses at
+ 12.5° and boils at;;2S3°-2S4°.

HIGHER FATTY ACIDS.

These (p. 215) are chiefly solids at ordinary temperatures, and
can usually be distilled without suffering decomposition. They are
volatilized by superheated steam. They are insoluble in water,
but readily soluble in alcohol and ether, from which they may
be crystallized out. In the naturally occurring oils and solid
fats, they exist in the form of glycerol esters (see these). When

HIGHER FATTY ACIDS.

231

fats are saponified by potassium or sodium hydroxide, salts of
the fatty acids — soaps — are produced. The sodium salts are solids
and hard, while those with potassium are soft. Salt water will con-
vert potash soaps into sodiuip soaps. In small quantities of water
the salts of the alkalies dissolve completely, but with an excess of
water they suffer decomposition, some alkali and fatty acid being
liberated. The action of soap depends on this fact. The remain-
ing metallic salts of the fatty acids are sparingly soluble or insoluble
in water, but generally dissolve in alcohol. The lead salts, formed
directly by boiling fats with litharge and water, constitute the
so-called lead plaster.

The natural fats almost invariably contain several fatty acids (frequently, too ,
oleic acid). To separate them, the acids are set free from their alkali salts by
means of hydrochloric acid and then fractionally crystallized from alcohol. The
higher, less soluble acids separate out first. The separation is more complete if
the acids be fractionally precipitated (see p. 216). The free acids are dissolved
in alcohol, saturated with ammonium hydroxide and an alcoholic solution of mag-
nesium acetate added. The magnesium salt of the higher acid will separate out
first, this is then filtered off and the solution again precipitated with magnesium
acetate. The acids obtained from the several firactions are subjected anew to the
same treatment, until, by further fractionation, the milting point of the acid
remains constant — an indication of- purity. The melting point of a mixture of
two fatty acids is usually lower than the melting points of both acids (the same is
the case with alloys of the metals).

The fatty acids existing in fats and oils all possess the normal
structure 6i the carbon chains, inasmuch as they yield only lower
and normal acids when oxidized. It is an interesting fact, that in
the natural fats only acids exist that have an even number of carbon
atoms. Those that possess an uneven number of carbon atoms (as
undecylic and tridecylic) are artificially prepared by the oxidation
of their corresponding ketones (p. 200). The latter are obtained
by distilling the calcium salt of an acid having one carbon atom
more, with calcium acetate. In this manner there is derived from
lauric acid, C11H23.CO2H, the ketone, C11H23.CO.CH3, which is
oxidized to undecylic acid, QiHajOa = CioH^i.COzH, by chromic
acid. Undecylic acid yields the ketone, C10H21.CO.CH3, and this
the acid, C10H20O2, etc. Thus, starting with the highest acid, we
can successively form all the lower members of the series.

Capric Acid, CjoHjoOj, present in butter, in cocoanut oil and in many fats,
forms a crystalline mass, melting at 31.4°, and boiling, with partial decomposi-
tion, at 268°-27o°- The barium salt crystallizes from alcohol in fatty, shining
needles or scales. The ethyl ester is a liquid, and possesses a fruit-like odor. It
boils at 243°.

Undecylic Acid, CuHjaOjtis obtained by oxidation from undecyl-methyl
ketone, CnHjj.CO.CHj (see above), and from undecylenic acid, when the latter
is heated with hydriodic acid. It is a scaly, crystalline mass, which melts at 28.5°,

232 ORGANIC CHEMISTRY.

and boils at 212° under a pressure of 100 mm. An acid obtained from the fruit
of the California bay-tree appears to be identical with the preceding acid.

Laurie Acid, Cj^H^^O^, occurs as glycerol-ester in tlie iraitof Laurus nobilis
and in pichuriutn beans. It crystallizes in lame, brilliant needles, melting at 43-^°'
The ethyl ester possesses a fruit-like odor, anTrooils at 269°.

Tridecylic Acid, CuHzsOzi'^ formed by the oxidation of tridecyl-metbyl
ketone, CijHj^CO.CHj (from myristic acid), and crystallizes in scales, which
melt at 40.5° and under 100 mm. pressure boil at 235°.

Myristic Acid, C-^^^fi^, obtained from muscat butter (from Myrisiica mos-
chaid), from spermaceti and oil of cocoanut, is a shining, crystalline mass, melting
at 54°. The ethyl ester is solid.

Pentadecatoic Acid, CuHjdOj,, is prepared from pentadecato-methyl ketone,
C15H31.CO.CH3 (from palmitic acid); it melts at 51°, and boils under a pressure
of 100 mm. at 257°.

Palmitic Acid, CieHgjOj. The glycerol-ester of this acid and
that of stearic acid constitute the principal ingredients of solid ani-
mal fats. The stearin employed in the candle manufacture is a
mixture of free palmitic and stearic acids. Palmitic acid occurs in
rather large quantities, partly uncombined, in palm oil. Spermaceti
is the cetyl-ester of the acid, while the myricyl ester is the chief
constituent of beeswax. The acid is most advantageously obtained
from olive oil, which consists almost exclusively of the glycerides of
palmitic and oleic acid (see latter) ; also, from Japanese beeswax, a
glyceride of palmitic acid {Berichte, 21, 2265). The acid is arti-
ficially made by heating cetyl alcohol with soda-lime : —

Ci.Hji.CH^.OH -t- KOH = C^Hji.CO^K + 2H, ;

also by fusing together oleic acid and potassium hydroxide.

Palmitic acid crystallizes in white needles, which melt at 62°, and
solidify to a crystalline mass.

Margaric Acid, C17H34O2, does not apparently exist naturally
in the fats. It is made in an artificial way by boiling cetyl cyanide
with caustic potash: —

CisHas-CN + 2H,0 = Ci.Hjj.CO.H -f NH,.

The acid bears great resemblance to palmitic acid, and melts at

S9-9°-

Stearic Acid, CieHseOa, is associated with'^almitic and oleic
acids as a mixed ether in solid animal fats^j^e tallows. The acid
crystallizes from alcohol in brilliant leaflets, melting at 62.2°.

The so-called stearin of candles consists of a mixture of stearic and
palmitic acids. For its preparation, beef tallow and suet, both solid
fats, are saponified with potassium hydroxide or sulphuric acid. The
acids which separate are distilled with superheated steam. The yel-
low, semi-solid distillate, a mixture of stearic, palmitic and oleic
acids, is freed from the liquid oleic acid by pressing it between

UNSATURATED ACIDS. 233

warm plates. The residual, solid mass is then fused together with
some wax or paraffin, to prevent crystallization occurring when the
mass is cold, and molded into candles.

Cetyl Acetic Acid, Cj5H33.CH2.CO2H, is probably identical with the above,
and is obtained from cetyl acetoacetic ester and cetyl malonic acid (see p. 212)
[Berichie, 17, 1629). An isomeric acid, called dioctyl acetic acid (C8H„)2CH.
CO2H, is prepared from dioctyl-aceto-acetic ester and from dioctylmalonic acid.
It melts at 38.5°.

We may briefly mention the following higher acids (see p. 215) : —

Arachidic Acid, C^oH^jOj, occurs in earth-nut oil (from Arachis hypogma),
and is composed of shining leaflets, melting at 75°. It has been obtained syn-
thetically from aceto-acetic ester and octodecyl iodide (from stearyl aldehyde) {JBe-
richte, 17, Ref. 570).

Cerotic Acid, C2,H5,02, or CggHj^Oj (see Annalen, 224, 225), occurs in a
free condition in beeswax, and may be extracted from this on boiling with alcohol.
As ceryl ester, it constitutes the chief ingredient of Chinese wax. On boiling the
latter with an alcoholic potash solution, potassium cerotate and ceryl alcohol are
produced. The acid may also be obtained by oxidizing ceryl alcohol, or by fusing
it with KOH :—

C2,H5,0 4- KOH =C2,H5302K + 2H2.

It crystallizes from alcohol in delicate needles, melting at 78°.

Melissic Acid, CjjHgjO,, is formed from myricyl alcohol (p. 134) when the
latter is heated with soda-lime. It is a waxy substance, melting at 88°, and is
really, as it appears, a mixture of two acids. The so-called Theobromic Acid,
C54H128O2, obtained from cacao butter, melts at 72°, and is apparently identical
with arachidic acid.

2. UNSATURATED ACIDS, CnH^n-aO,.

Acrylic Acid, C3H4O2 == C2H3.CO2H

Crotonic " QHeO^ = C3H5.CO2H

Angelic " C5H3O2 = C4H,.C02H

Pyroterebic " QHi„02 = C5H9.CO2H

Oleic Acid, C^^^^fi^ — Erucic Acid, C^jH^jOj.

The acids of this series, bearing the name Oleic Adds, differ
from the fatty acids by containing two atoms of hydrogen less than
the latter. They also bear the same relation to them that the alco-
hols of the allyl series do to the normal alcohols. We can consider
them derivatives of thaalkylens, C^Hj^, produced by the replace-
ment of one atom of hydrogen by the carboxyl group. In this
manner their possible isomerides are readily deduced.

As unsaturated compounds the oleic acids are capable of com-
bining directly with two affinities, when the double union of the two
carbon atoms becomes simple. Hence they unite directly with the
halogens and halogen hydrides : —

CH2:CH.C02H + Br^ = CH2Br.CHBr.CO2H.
Acrylic Acid. a;8-Dibrompropionic Acid.

20

234 ORGANIC CHEMISTRY.

On combining with two hydrogen atoms they become fatty

acids : —

CHjiCH.COjH 4- Hj = CH3.CH2.CO2H.
Acrylic Acid. Propionic Acid.

The lower members, as a general thing, combine readily with the Hj evolved
in the action of zinc upon dilute sulphuric acid ; while the higher remain unaf-
fected. All may be hydrogenized, however, by heating with hydriodic acid and
phosphorus [Berichte, 12, Ref. 376). The union with halogen hydrides occurs
somewhat differently than observed with the alkylens. The halogen atom does
not, as in the latter instance, attach itself to the carbon atom carrying the least
number of hydrogen atoms, but prefers the /3 or 7 position (p. 225).

The methods employed for the preparation of the unsaturated
acids are similar to those used with the fatty acids, since the latter
can be obtained from the" unsaturated compounds by analogous
methods. They are formed from the saturated fatty acids by the
withdrawal of two hydrogen atoms, just as the alkylens are derived
from the normal hydrocarbons : —

(i) Like the fatty acids they are produced by the oxidation of
their corresponding alcohols and aldehydes ; thus allyl alcohol and
its aldehyde afford acrylic acid : —

CH^rCH.CHj.OH and CH^rCH.CHO yield CH^jCH.CO^II.
Ailyl Alcohol. Acrolein, Acrylic Acid.

(2) Some may be prepared synthetically from the halogen deriv-
atives, CaH2n_iX, aided by the cyanides (see p. 211); thus allyl
iodide yields allyl cyanide and crotonic acid : —

C,HJ forms C,H,.CN and C,H,.CO,H.

ditioned by the structure of the latter. Although allyl iodide, CHjiCH.CHjI,
yields a cyanide, ethylene chloride, CHjrCHCl, and /3-chlorpropylene, CH3.CCI:
CH 2, are not capable of this reaction.

(3) Another synthetic method is to introduce the allyl group, C3H5 (by means
of allyl iodide), into aceto-acetic ester and malonic ester, and then further trans-
pose the products first formed (p. 212). Allyl acetic acid, C3H5.CH2.CO2H, and
diallyl acetic acid, (C3H5)2CH.C02H, have been obtained in this manner.

(4) Some acids have been synthetically prepared_by Perkins' reaction. This
is readily executed with benzene derivatives. It consists in letting the aldehydes
act upon a mixture of acelic anhydride and sodium acetate (compare Cinnamic
Acid): C^HijCHO -f CHj-CO^Na = CeHi3.CH = CH.COjNa + H^O

CEnanthol. Nonylenic Acid.

(Annaltn, 227, 79).

Pyroracemic acid acts analogously with sodium acetate ; carbon dioxide splits
off and crotonic acid results (Berichte, 18, 987).

(5) Unsaturated /Jy-acids are prepared by distilling alkylized paraconic acids.
Thus methyl paraconic acid yields ethylidene propionic acid (Berichte, 23,
Ref. 91) : C.HjO^ = C,\ifi^ + CO^.

UNSATURATED ACIDS. 235

Generally, the unsaturated acids are prepared from the satu-
rated by

(i) The action of alcoholic potash (p. 80) upon the monohalo-
gen derivatives of the fatty acids : —

CH3.CH2.CHCI.CO2H and CH3.CHC1.CH,.C02H yield CH3.CH:CH.C0,H.

o-Chlorbutyric Acid. ;8-ChIorbutyric Acid. Crotonic Acid.

The /?- derivatives are especially reactive, sometimes parting with halogen hy-
drides on boiling with water (p. 223). (The 7-halogen acids yield oxyacids and
lactones.) Similarly, the a/3-derivatives of the acids (p. 225) readily lose two
halogen atoms, either by the action of nascent hydrogen —

CH2Br.CHBr.CO2H + 2H = CHjiCH.COjH + zHBr,

a^-Dibrompropionic Acid. Acrylic Acid.

or even more readily when heated with a solffltion of potassium iodide, in which
instance the primary di-iod-compounds part withiHodine (p. 99).

CH2I.CHI.CO2H = CH^iCH.cbjH + Ij.

(2) The removal of water (in the same manner in which the
alkylens CnHa^ are formed from the alcohols) from the oxy-fatty
acids (the acids belonging to the lactic series) : —

CH3.CH(OH).C02H and CH2(OH).CH2.C02H yield CHjiCaCOaH.
o-Oxypropionic Acid. ^-Oxypropionic Acid. Acrylic Acid.

Here again the ;3-derivatives are most inclined to alteration, losing water when
heated. The removal of water from a-derivatives is best accomplished by acting
on the esters with PCI 5. The esters of the unsaturated acids are formed first, and
can be saponified by means of alkalies.

(3) From the unsaturated dicarboxylic acids, containing two car-
boxyl groups attached to one carbon atom (see p. 212) : —

CH3.CH:C(C02H)2 = CHj.CHrCH.COjH -f CO^.
Ethidene Malonic Acid. Crotonic Acid.

Like the saturated acids in their entire character, the unsaturated
derivatives are, however, distinguished by their ability to take up
additional atoms (p. 234). Their behavior, when fused with potas-
sium or sodium hydroxide, is interesting, because it affords a means
of ascertaining their structure. By this treatment their double
union is severed and two monobasic fatty acids result : —

CHjiCH.CO^H -|-2H20= CH^Oj -|- CHj.CO^H + H^,

Acrylic Acid. Formic Acid. Acetic Acid.

CH3CH;CH.C02H + zHfi = CHj.CO^H + CH3.CO2H + H^.

Crotonic Acid. Acetic Acid. Acetic Acid.

236 ORGANIC CHEMISTRY.

Oxidizing agents (chromic acid, nitric acid, permanganate of potash) have the
same effect. The group linked to carboxyl is usually (jirther oxidized, and thus
a dibasic acid results.

When carefully oxidized with permanganate (see p. 82), the unsaturated acids sus-
tain an alteration similar to that of the defines; dioxy-acids result (Saytzeff, Fittig,
Hazura, Berichte, 21, 919, 1648, 1878). For example, phenylacrylic acid yields
phenylglyceric acid : —

CJis.CHrCH.CO.H + O + H,0 = CeH5.CH(OH).CH(OH).CO,H.
Phenylacrylic Acid. Phenylglyceric Acid.

When the unsaturated acids are heated to 100°, with KOH or NaOH, they fre-
quently absorb the elements of water and pass into oxy-acids. Thus, from acrylic
acid we obtain a-lactic acid (CH^iCH.CO^H + H^O = CH3.CH(OH).C02H),
and malic from fumaric acid, etc.

I. Acrylic Acid, CsHiO., = CH^rCH.COjH, the lowest mem-
ber of this series, is obtained according to the general methods : —

(i) From iod-propionic acid by the action of alcoholic potash or
lead oxide.

(2) From a/?-dibrompropionic acid by the action of zinc and sul-
phuric acid, or potassium iodide.

(3) By heating /3-oxypropionic acid (hydracrylic acid).

The best method consists in oxidizing acrolein with silver oxide.

The aqueous solution (3 parts HjO) of acrolein is mixed with silver oxide, di-
gested for some time in the cold and then heated to boiling. Sodium carbonate
is next added, the filtrate concentrated and distilled with dilute sulphuric acid.
The acrylic acid in the distillate is converted into the silver or lead salt, which is
decomposed by heating in a current of H^S, that the acid may be obtained in an
anhydrous condition.

Acrylic acid is a liquid with an odor like that of acetic acid, and
solidifies at low temperatures to crystals melting at -\- 7°. It boils
at 139-140°, and is miscible with water. If allowed to stand for
some time it is transformed into a solid polymeride. By protracted
heating on the water bath with zinc and sulphuric acid it is con-
verted into propionic acid. This change jjdoes not occur in the
cold. It combines. with bromine to form a/?-Qibrompropionic acid,
and with the halogen hydrides to yield /J-substitution products of
propionic acid (p. 224). If fused with caustic alkalies it is broken
up into acetic and formic acids.

The salts of acrylic acid, the silver salt excepted, are very soluble in water and
crystallized with difficulty. They suffer decomposition when heated to 100°.
The silver salt, CjHjOjAg, consists of shining needles which blacken at 100°.
The lead salt, (CjHjOjjjPb, crystallizes in long, silky, glistening needles.

UNSATURATED ACIDS. 237

The ethyi ester, C5H302.C2H5^ obtained from the ester of a^dibrompropionic
acid by means of zinc and sulphuric acid, is a pungent-smelling liquid boiling at
101-102°- The methyl ester boils at 85°, and after some time polymerizes to a
solid mass. •

Substitution Products. There are two isomeric forms of mono-substituted
acrylic acids (p. 223) : —

CHjjiCCl.COjH and CHChCH.CO^H.
a-Derivatives. ^-Derivatives.

a-Chloracrylic Acid is probably the acid which results when a/3-dichIorpro-
pionic acid is heated with alcoholic potash (Berichte, 18, 241). It crystallizes in
needles, melts from 64-65°, and is even volatile at ordinary temperatures. It com-
bines with HCl at 100° to produce a/3-dichlorpropionic acid {Berichte, 10, 1499;
18, 244).

;8- Chloracrylic Acid is produced together with dichloracrylic acid in the re-
duction of chloralid with zinc and hydrochloric acid (Annalen, 239, 263), also
from propiolic acid, C^HjOj (p. 244), by the addition of HCl. It crystallizes in
leaflets and melts at 84° [Annattn, 203, 83). The ethyl ester boils at 142-144°,
and is most easily obtained from the ester of trichlorlactic acid by reduction with
zinc and hydrochloric acid in alcoholic solution. The ester of dichloracrylic acid
is obtained at the same time.

a-Bromacrylic Acid is prepared from a- and a/3-dibrompropionic acids with
alcoholic potash (Berichte, 14, 1867). It crystallizes in large plates melting at
69—70°. It combines with H]3r to form o^-dibrompropionic acid.

;8-Bromacrylic Acid is obtained from the chloralid of tribromlactic acid when
this is reduced with zinc and hydrochloric acid. It may also be prepared from
propiolic acid by the addition of HBr (Berichte, 19, 541). It consists of fine
needles, melting at 115-116°.

lodoacrylic Acid, CjHjIOj (probably /3), is obtained from propiolic acid by
the addition of HI. It forms leaflets melting at 140°. There is also formed at
the same time an acid melting at 65°, which probably is the second possible geo-
metrical isomeride [Berichte, 19, 542).

There are two disubstituted acrylic acids : —

CHXrCX-CO^H and CX^iCH.CO^H.
aP-Derivative. ;3-Derivative. _

reiS-Dibromacrylic Acid is obtained from mucobromic acid and tribromsuccinic
acid ; and the /3-Dibromacrylic Acid from the latter and also from brompropiolic
acid by the addition of HBr (p. 245). Both acids melt from 85-86° [Berichte,
19, 1396).

a,3-Di-iodo-acrylic Acid, formed by the addition of iodine to propiolic acid,
melts at 106°. /3-Di-iodo-acrylic Acid is produced by the addition of HI to
iodopropiolic acid. It melts at 133° [Berichte, 18, 2284I.

238 ORGANIC CHEMISTRY.

2. THE CROTONIC ACIDS, C^HjOj = C3H5.CO2H.

According, to the current representations of the constitution of
the unsaturated monocarboxylic acids three isomerides of the above
formula are possible : — *

I. CH3 — CH = CH — COjH 2. CH2 = CH — CHj — COjH

Normal Crotonic Acid. Isocrotonic Acid.

Methylacrylic Acid.

The first formula is attributed to the ordinary solid crotonic acid,
while the second is ascribed to the liquid isocrotonic acid. Yet it
would seem that the same structural formula (i) belonged to both
acids, and that relations existed here similar to those noted with
maleic and fumaric acids, for which the present structural formulas
give no explanation.

Following J. Wislicenus, it is assumed that crotonic and isocrotonic acids have
the same structural formula. They are geometrical or stereochemical isomerides,
corresponding to the formulas : —

HC.CH3 HC.CH3

II and II

HC.CO2H HOjC.CH.

Crotonic Acid. IsocrotoDic Acid.

The first occupies the plane-symmetric and the second the central symmetric
position (p. 52). This seems to be confirmed by the formation of ordinary cro-
tonic acid from tetrolic acid by means of sodium amalgam {Berichte, 22, 1 183).
The analogy with the two cinnamic acids, CgHj.CHiCH.COjH, favors this as-
sumption. The differences between these la.st two acids cannot be explained by
structural formulas.

Two mono-chloracids can be derived from each of the two stereo-isomeric cro-
tonic acids [Berichte, 20, Ref. 449; 22, Ref. 51 and 816).

I. Ordinary Crotonic Acid is obtained : —
(i) By the oxidation of crotonaldehyde, CHa.CHiCH.COH (p.
199).

(2) By the dry distillation of ;S-oxybutyric acid, CH3.CH(0H.).
CH^.CO.H.

(3) By the action of alcoholic potash upon a-brombutyric acid,
and KI upon a/3-dibrombutyric acid.

(4) From allyl iodide by means of the cyanide.

(5) By the action of sodium amalgam on tetrolic acid {Berichte,
21, Ref. 494).

* A supposed fourth crotonic acid, the so-called vinyl acetic acid (from the
so-called vinylmalonic acid) appears identical with trimethyl carboxylic acid
derived from trimethylene.

THE CROTONIC ACIDS. 239

The most practicable method of obtaining crotonic acid is to
heat malonic acid, CH2(C02H)2, with paraldehyde and acetic
anhydride. The ethidene malonic acid first produced decomposes
into CO2 and crotonic acid (p. 235) {Annalen, 218, 147).

Crotonic acid crystallizes in fine, woolly needles or in large plates,
which fuse at 72° and boil at 182°. It dissolves in 12 parts water
at 20°. The warm aqueous solution will reduce alkaline silver solu-
tions with the formation of a silver mirror. Zinc and sulphuric acid,
but not sodium amalgam, convert it into normal butyric acid. It
combines with HBr and HI to yield ;S-brom- and iodbutyric acid,
and with chlorine and bromine to a/S-dichlor- and dibrombutyric
acid. When fused with caustic potash, it breaks up into two mole-
cules of acetic acid ; nitric acid oxidizes it to acetic and oxalic
acids.

a-Chlorcrotonic Acid, CH^.CHiCCl.COjH, is obtained when trichlorbutyric
acid (p. 227) is treated with zinc and hydrochloric acid, or zinc dust and water.
Further, by the action of alcoholic potash on a/3-dichlorbutyric ester [Berichie, 21,
Ref. 243). It melts at 99°, boils at 212°, and is not affected when boiled with
alkalies (see below).

/3-Chlorcrotonic Acid, CHg.CCLCH.CO^H, is obtained in small quantities
(together with /3-chlorisocrotonic acid) from aceto-acelic ester, and by the addition
of HCl to tetrolic acid {Berichte, 22, Ref. 51). It melts at 94.5° and boils at 2oS°.
Sodium amalgam reduces it to crotonic acid, and with boiling alkalies it yields te-
trolic acid (p. 244). Sodium amalgam converts both a- and /3-chlorcrotonic acid
into ordinary crotonic acid.

(i-Bromcrotonic Acid, from the ester of dibrombutyric acid, melts at 106.5°.
/?-Bromcrotonic Acid, formed by the addition of HBr to tetrolic acid, melts at
92° [Berichie, 22, Ref. 243).

(2) Isocrotonic Acid, CH2:CH.CH2.C02H(?), is obtainedfrom /3-chlorisocro-
tonic acid by the action of sodium amalgam and similarly from the achlor-acid. It
is a liquid which does not solidify; boils at 172°, and has a specific gravity of
i.oiS at 25°. When heated to I70°-l8o°, in a sealed tube, it changes to ordi-
nary crotonic acid. This alteration occurs partially, even during distillation. This
explains why upon fusing isocrotonic acid with KOH, formic and propionic acids
(which might be expected), are not produced, but in their stead acetic acid, the
decomposition product of crotonic acid. Sodium amalgam does not change it. It
combines with HI to yield j8-iodo-butyric acid [Berichte, 22, Ref 741). It yields
a liquid dichloride, C^HgCljOj (Iso-a/3-dichlorbutyric acid), with Clj. This passes
intoa-chlorcrotonic acid. Sodium amalgam converts this acid into butyric acid.

a Chlor-isocrotonic Acid, CH3.CH:CC1.C02H (?), is obtained by the action
of sodium hydroxide on free aj3-dichlorbutyric acid. It is the most soluble of the
four chlor-crotonic acids. It crystallizes in needles, melting at 66.5° {Berichte, 22,
Ref. 52).

When PCI 5 and water act upon aceto-acetic ester, CH3.CO.CH2.CO.C2H5,
;3-chlorisocrotomc acid (with /3-chlorcrotonic acid) is produced. It is very probable
that /3-dichlorbutyric acid is formed at first, and this afterwards parts with HCl. It
is also formed by protracted heating of /3-chlorcrotonic acid.

Sodium amalgam converts both the a- and ^-chlorisocrotonic acid into liquid iso-
crotonic acid [Berichte, 22, Ref 53).

a-Bromisocrotonic Acid, CHj.CHrCBr.CO^H (?), is produced by the action

240 ORGANIC CHEMISTRY.

of sodium hydroxide upon free a/3-dibrombutyric acid. It melts at 90°-92° {JBe-
richte, 21, Ref. 242). /PH

(3) Methacrylic Acid, CH2:C<^^q«jj Its ethyl ester was first obtained

by the action of PCIg upon oxy-isobutyric ester, (CH3)2.C(OH).C02.C2Hj. It
is, however, best prepared by boiling citrabrompyrotartaric acid (from citraconic
acid and HBr) with water or a sodium carbonate solution : —

C5H,BrO^ = C.HeO, + CO, + HBr.

It consists of prisms that are readily soluble in water, fuse at +'6°, and boil at
160.5°. NaHg converts the acid into isobutyric acid. It combines with HBr and
HI to form a-brom-, and iod-isobutyric acid, and with bromine to form a/3-dibrom-
isobutyric acid, which confirms the assumed constitution [Journ. pr. Chemie, 25,
369). When fused with KOH, it breaks up into propionic and acetic acids.

3. ACIDS OF FORMULA C5H3O2 = CiHj.CO^H.

Of the many isomerides of this formula angelic and tiglic acids appear to bear
the same relation to each other that was observed with crotonic and isocrotonic
acids (p. 238). Both probably have the same structural formula [Annalen, 216,
161). According to Wislicenus they are only geometrical isomerides. They cor-
respond to the stereochemical formulas : —

CH3.CH HC.CH3

II and II

CH3.C.CO2H CH3.C.CO2H.

a-Methyl-isocrotonic Acid. a-Methyl-crotonic Acid.

Angelic Acid. Tiglic Acid.

When fused with alkalies, both acids split up into acetic and propionic acids.
They yield methyl-ethyl acetic acid when heated with HI and phosphorus. They
form two different dibromides with bromine ; these yield two different brombuty-
lenes [Annalen, 250, 240).

I. Angelic Acid, C4H,.C02H, exists free along with valeric
and acetic acids in the roots of Angelica arckangelica, and as butyl
and amyl esters in Roman oil of cumin.

To prepare the acid, boil the angelica roots with milk of lime, and distil the
solution of the calcium salt with sulphuric acid. From the oily distillate, con-
taining acetic, valeric and angelic acids, the latter crystallizes on cooling. The
saponification of Roman cumin oil with potash, also furnishes the acid [Annalen,
250, 242).

Roman oil of cumin (from Artemis nobilis) contains the esters of several acids.
The following fractions may be obtained from that portion of it which boils up to
210°:—

1. Isobutyl butyrate, boiling 147-148°.

2. " angelate, " 177-178°.

3. Amyl angelate, " 200-201°-

4. Amyl tiglate, " 204-205°.

When these esters are saponified and distilled with sulphuric acid, the free acids
are obtained. We can separate angelic and tiglic acids by means of the calcium
salts, that of the first being very readily soluble in cold water. [Berichie, 17,
2261).

TERACRYLIC ACID. 241

Angelic acid crystallizes in shining prisms, melts at 45", and boils
at 185°. When boiled for some time it is converted into tiglic
acid. Concentrated .sulphuric acid at 100°, effects the same. Thp
acid dissolves readily in hot water and alcohol. It is volatile with
steam. Its ethyl ester, CjHjOj.CjHs, boils at 141°.

2. a-Methylcrotonic Acid, CH3.CH:C(f „„ '„ (?) Tiglic Acid, present in

Roman oil of cumin (see above), and in Croton oil (from Croton tiglium), is a
mixture of glycerol esters of various fatty and oleic acids. It is obtained artificially

by acting with PCI3 upon methyl-ethyl oxy-acetic acid, ^„ ppr' / C(0H).C02H

(its ester), and from amethyl-/3-oxybutyric acid, CH3.CH(OH).Cir(CH3).C02H,
on heating the latter to 200° (Annalen, 250, 243).

Tiglic acid crystallizes in prisms or tables, is soluble vpith difficulty in water,
melts at 64.5°, and boils at 198°. Its ethyl ester, CjHjOj.CjHj, boils at 152°.

3. AUyl-acetic Acid, CHjiCH.CHj.CHj.CO^H, obtained from allylaceto-
acetate and allyl malonic acid (p. 235), is an oil, smelling like valeric acid, and
boiling at 188°. Nitric acid oxidizes it to succinic acid. It unites with concen-
trated hydrobromic acid, and forms y-bromvaleric acid (a non-solidifying oil),
which, upon heating with water, parts with HBr and yields the lactone of y-oxy-
valeric acid (see Lactones).

4. Propylidene Acetic Acid, CHj.CHj.CHiCH.COjH, is obtained from
propylidene malonic acid, C3H5:C(C02H)2 (p. 235), and boils at 196° {Anna-
len, 218, 160). It has also been obtained from pyrocatechol and amidophenol
(Berichte, 22, 495).

5. Ethidene Propionic Acid, CHj.CHiCH.CHj.COjH, is produced by the
distillation of methyl paraconic acid, CgHjO^. It is a liquid boiling at 104°. It
unites with HBr to y-bromvaleric acid, which readily passes into valerolactone
(Berichte, 23, Ref. 91).

6. Dimethyl Acrylic Acid, (CH3)2C:CH,C02H, is obtained from /3-oxy-
isovaleric acid, (CH3)2.C(OH).CH2.C02H, by distillation with dilute sulphuric
acid. It melts at 70°-

Tetramethylene carboxylic acid (see this) is isomeric with these unsaturated
acids.

The following higher, unsaturated acids, may also be mentioned. Little is
known concerning their constitution. They frequently sustain molecular transpo-
sitions : —

Pyroterebic Acid, C8H,„02 = (CH3)2.C:CH.CH2.C02H, is formed in small
quantity (together with the isomeric lactone of y-oxy-isocaproic acid) (see this), in
the distillation of terebic acid, CjHjjOj {Annalen, 208, 39 and 119). It is an oil
which does not solidify at — 15°. The calcium salt, (CjHg02)2Ca 4- 3H2O,
crystallizes in shining prisms. Protracted boiling causes the free acid to change
to isomeric isocaprolactone : —

(CH3)2.C:CH.CH2.C02H forms (CH3)2.C.CH2.CH2 _

t) CO

concentrated hydrobromic acid effects the same change.

Teracrylic Acid, C,Hij02 = CjHj.CHrCH.CH^.COjH, is obtained by the
distillation of terpentic acid, C^yfif, (see this), just as pyroterebic acid is formed
from terebic acid. An oily liquid, with an odor resembling that of valeric acid,
and boiling at 208° without decomposition. HBr converts it into the isomeric
lactone of y-oxyheptoic acid, C7Hi3(OH)02.

242 ORGANIC CHEMISTRY.

Nonylenic. Acid, CgHijOj = CH3(Cn2)5CH:CH.C02H, is obtained from
oenanthol (p. 198) by Perkins' reaction (p. 234). It is an tiily liquid, which vola-
tilizes with steam.

^Decylenic Acid, CjoHijOj, formed together with decylacetone in the distilla-
tion of hexylparaconic acid {Berickte, 18, Ref. 144), solidifies in the cold and melts
at + 10° C.

Undecylenic Acid, C^-Jrl^^O^, is produced by distilling castor oil under
reduced pressure, when the ricinoleic acid, CjgHj^Oj (p. 243), present as a glycer-
ide, breaks up into oenanthol, C^HijO, and undecylenic acid. It melts at 24.5°,
and boils with partial decomposition at 275°. It distils unchanged under reduced
pressure. When fused with caustic potash, it splits up into acetic and nonoic
acid, CgHigO. Hence its structure corresponds to the formula, CgHi,.CH:CH.
CO2H. (compare Berichte, ig, Ref. 338, and ig, 2224),

Hypogseic Acid, CijHjqOj, found as glycerol ester iu earthnut oil (from the
fruit of Arachis. hypogad), crystallizes in needles, and melts at 33°. Nitrous acid
converts it into an isomeric modification — gaeidinic acid, melting at 38°.

Oleic Acid, CigHsiOj, occurs as glycerol ester (triolein) in
nearly all fats, especially in the oils, as olive oil, almond oil, cod-
liver oil, etc. It is obtained in large quantities as a by-product in
the manufacture of stearin candles.

In preparing oleic acid, olive or mandel oil is saponified with potash and the
aqueous solution of the potassium salts precipitated with sugar of lead. The lead
salts which separate are dried and extracted with ether, when lead oleate dissolves,
leaving as insoluble lead palmitate, stearate and the salts of all other fatty acids.
•Mix the ethereal solution with hydrochloric acid, filter off the lead chloride, and
concentrate the liquid. To purify the acid obtained in this way, dissolve it in am-
monium hydroxide, precipitate with barium chloride, crystallize the barium salt
from alcohol, and decompose it away from the air by means of tartaric acid.

Oleic acid is a colorless oil, which crystallizes on cooling. It
melts at -f- 14°- In a pure condition it is odorless, and does not
redden litmus. On exposure to the air it oxidizes, becomes yellow
and acquires a rancid odor. On fusion with caustic potash it splits
up into palmitic and acetic acids. Nitric acid oxidizes it with for-
mation of all the lower fatty acids from capric to acetic, and at the
same time dibasic acids, like sebacic acid, are produced. A per-
manganate solution oxidizes it to azelaic acid, CgHieOj. Moderated
oxidation produces dioxystearic acid. The oleates are very similar
to the salts of the fatty acids. Much water decomposes them.
The solubility of the lead salt, (Ci8H3302).iPb, in ether is charac-
teristic.

When heated to 200° with hydriodic acid and phosphorus, or
with iodine (i %) to 280°, oleic changes to stearic acid, CigHjeOz.
It unites with bromine to form liquid dibromstearic acid, CisHsiBrjO^,
which is converted by alcoholic KOH into monobromoleic acid,
CisHsjBrOj, and then into stearoleic acid.

LINOLEIC ACID. 243

Nitrous acid changes oleic into the isomeric crystalline
Elaidic Acid, CigHj^Oj. This consists of brilliant leaflets,
melting at 44°-45°. If fused with potash it decomposes into pro-
pionic and acetic acids. Hydriodic acid and phosphorus convert
it into stearic acid. With bromine it yields the bromide, CigHgjBrj
O2, which melts at 27°, and when acted upon with sodium amal-
gam, passes back into elai'dic acid.

Iso-oleic acid, obtained by the distillation of oxystearic acid, appears to be dif-
ferent from elaidic acid. It also melts at 45° {Berichte, 21, Ref. 398; 21, 1879).

Erucic Acid, C^^^^O^, is present as glyceride in rape-seed oil (from Bras-
sica campestris) and in the fatty oil of mustard". For its preparation, rape-seed oil
is saponified with lead oxide, and the lead erucate removed with ether. Erucic
acid crystallizes from alcohol in long needles, which melt at 33°-34°. It forms
■o. dibromide, ^,^^,^^^^^,1^, with bromine. This crystallizes in warty masses,
melting at 42°, and when acted upon with alcoholic potash, changes to bromerucic
acid, melting at 33°.

Hot nitric acid (Berichte, ig, 3321) converts erucic acid into isomeric brassidic
acid, melting at 56°. •

The petrolic acids, found in the different varieties of petroleum, are isomeric
with the oleic acids. Up to the present time the following have been isolated :
CnH2|)02, CjjHj^Oj and CjjHggOj. In all probability they are the carbox-
ylic acids of the naphthenes (p. 78) (Berichte, 20, 596; 23,

Linoleic and ricinoleic acids, although not belonging to the same
series, yet closely resemble oleic acid. The first is a simple, unsat-
urated acid, the second an unsaturated oxy-acid.

Linoleic Acid, CigHajOj, occurs as glyceride in drying oils (see
glycerol), such as linseed oil, hemp oil, poppy oil and nut oil. In
the non-drying oils we have the oleic-glycerol ester. To prepare
linoleic acid, saponify linseed oil with potash, precipitate the aque-
ous solution of the potassium salt with calcium chloride and dis-
solve out calcium linoleate with ether. Linoleic acid is a yellowish
oil that has a specific gravity of 0.921. It is not altered by nitrous
acid.

Various oxy-fatty acids are produced when linoleic acid is oxidized with potas-
sium permanganate. From the fact that they can be formed it has been concluded
that certain other acids (like linolenic and isolinolenic acid, CigHjoOj) exist in
the crude linoleic acid (Berichte, 21, Ref. 436 and 659).

Ricinoleic Acid, CigHajOs, is present in castor oil, in the form
of a glyceride. It is a colorless oil, which solidifies in the cold to
a hard, white mass, melting at 16-17°. The lead salt is soluble in
ether. Subjected to dry distillation ricinoleic acid splits into
oenanthol, QHuO, and undecylenic acid, CuHjoO^. Fused with
caustic potash it changes to sebacic acid, C8Hi6(C02H)2, and

secondary octylalcohol,^^^'^CH.OH. It combines with bro-

244 ORGANIC CHEMISTRY.

mine. to a solid dibromide. When heated with HI (iodine and
phosphorus) it is transformed into iodstearidic acid, C18H33IO2,
which yields stearic acid when treated with zinc and hydrochloric
acid. Nitrous acid converts ricinoleic acid into isomeric ricine-
laidic acid. This melts at 53° C. (see Berichte, 21, 2 73S)-

• UNSATURATED ACIDS, C^YL^^-^O^.
PROPIOLIC ACID SERIES.

The members of this series have four hydrogen atoms less than
the normal acids. They cap be obtained from the acids of the
acrylic series by treating the halogen derivatives of the latter with
alcoholic potash — ^just as the acetylenes are produced fom the de-
fines (see p. 87). Thus tetrolic acid, QHiOj, is obtained from the
bromide of crotonic acid, Q.^^x^O^, and from bromcrotonic acid,
CiHsBrOj. They must be viewed as acetylene derivatives, formed
by the replacement of one hydrogen ^tom by carboxyl ; conse-
quently they can be obtained by letting CO^ act upon the sodium
compounds of acetylene (p. 88) : —

CH^.C: CNa + CO2 = CHj.C: C.COjNa.
Sodium Allylene. Sodium Tetrolate.

Like the acetylenes they are capable of directly binding 2 and
4 affinities. From their structure they may contain one triple union
or two double unions of two carbon atoms (see p. 87).

Propiolic Acid, CsH^O^ = CH ; CCO^H, Propargylic Acid
(p. 135), corresponds to propargyl alcohol. The potassium salt,
C3HKO2 -|- HjO, is produced from the primary potassium salt of
acetylene dicarboxylic acid, when its aqueous solution is heated : —

C.COjH CH

III =111 +C02.-

C.C02K C.C02K

Acetic acid results in like manner from malonic acid (p. 212).

The aqueous solution of the salt is precipitated by ammoniacal
silver and cuprous chloride solutions, with formation of explosive
metallic derivatives. By prolonged boiling with water the potassium
salt is decomposed into acetylene and potassium carbonate.

Free propiolic acid, liberated from the potassium salt, is a liquid
with an odor resembling that of glacial acetic acid. When cool it
solidifies to silky needles which melt at -f 6°. The acid dissolves
readily in water, alcohol and ether, boils with decomposition at 144°
and reduces silver and platinum salts. Exposed to sunlight (away
from air contact) it polymerizes to trimesinic acid, 3C2H.CO2H =^
C6H3(C02H)3. Sodium amalgam converts it into propionic acid.
It forms /?-halogen acrylic acids with the halogen acids (p. 237)
{Berichte, 19, 543).

UNSATURATED ACIDS. 245

The ethyl ester, CjHOj.CjHj, is formed on digesting the acid with alcohol and
sulphuric acid. It boils at 119°. With ammoniacal cuprous chloride it unites to
a. stable yellow-colored compound. Zinc and sulphuric acid reduce it to ethyl
propargylic ester (p. 135) (Berichte, 18, 2271).

Chlorpropiolic Acid, CjHClOj, and Brompropiolic Acid, CjBrHO^, have
been obtained as barium salts from dichloracrylic and mucobromic acids, CjHjCljOj
and CjHjBr^Oj. They are readily decomposed with evolution of chlor- and brom-
acetylene. lodopropiolic Acid, CjHIOj = CI] C.CO2H, is obtained by saponi-
fying its ethyl ester with NaOH. It crystallizes from ether in small prisms, melting
at 140°. On warming its alkali salts with water carbonates and iodoacetylene are
produced. The acid combines with iodine to form tri-iodo-acrylic acid, C3HI3O2
, I [Berichte, 18, 2274 and 2282). The ethyl ester, CglO^.CjHj, may be prepared
from the Cu- derivative of propiolic ester (see above) by the action of iodine. It
crystallizes from ether in large prisms, melting at 68°. What is remarkable about
this compound is the stable union of the iodine contained in it (Berichte, 19, 540).

Tetrolic Acid, C^HjOj ^= CHj.C \ C.COjH, is obtained from /3 chlorcrotonic
acid and ^-chlorisocrotonic acid (p. 239) when these are boiled with potash
(Annalen, 2ig, 346) ; from sodium allylene by the action of COj (see above), and
from the chloride of allylene by means of Na and CO2. The acid consists of tables,
very readily soluble in water, alqphol and ether. It melts at 76° and boils at 203°.
At 210° the acid decomposes into CO^ and allylene, CjH^. Potassium perman-
ganate oxidizes it to acetic and oxalic acids. It combines with HCl and forms
^-chlorcrotonic acid.

Propyl-acetylene Carbonic Acid, CgH,.C \ C.COjH, from propylacetylene
sodium, CjHj.C \ CNa, melts at 27°. Isopropyl-acetylene Carbonic Acid,
from isopropyl acetylene, melts at 38° [Berichte, 21, Ref.' 178).

Sorbic Acid, CjHgOj = CjHj.COjH, occurs together with mahc acid in the
juice of unripe mountain-ash berries (from Sorbis aucufaria). Liberated from its
salts by distillation with sulphuric acid {Annalen, no, 129) it is an oil which does
not solidify until after it has been heated with potash. In cold water it is almost
insoluble, but crystallizes from alcohol in long needles, melting at I34-5°j a"<J dis-
tilling at 228° without decomposition. It combines with bromine and yields the
bromides, CjHaBr^O^ and CjHgBr402— the first melting at 95° and the second at
183°. The ethyl ester boils at 195°. Nascent hydrogen converts the acid into
hydrosorbic acid, CgHmOj. This possesses an odor like that of perspiration,
boils at 208°, and, wheil fused with KOH, yields acetic and butyric acids.

Diallylacetic Acid, CjHi^Oa = (C3H5)2.CH.C02H, is obtained from ethyl
diallyl-aceto-acetate and diallyl malonic acid. It is a liquid, boiling at 221°.
Nitric acid oxidizes it to tricarballylic acid : —

CHj.CaCHj CHj.CO^H

Diallyl-acetic Acid CH.CO^H yields CH.CO2H Tricarballylic Acid.

CHj.CHiCH^ CH^.CO^H

Undecolic Acid, CuHi j02,is obtained from the bromide of undecylenic acid
(p. 242). It fuses at 59.5°. Palmitolic Acid, C-^^Yi^fi^, isomeric with Imoleic
acid (p. 243), is obtained from the bromide of hypog^ic acid and gceldmic acid
(p. 242). It melts at 42°. Stearoleic Acid, C^^Yi^fi^, is obtained from oleic
• • and elaidic acids. It melts at 48°. Behenolic Acid, C^^H^oOj, from the bro-
mldes of erucic and brassidic acids, melts at 57.5°. On warming the last three
acids with 'fuming nitric acid they absorb 3 atoms of oxygen m a very peculiar
manner, and yield the monobasic acids: palmitoxylic , CuH^gO^, stearoxyhc,
C18H32O1, and behenoxylic, C^^H^oO,, which melt at 67°, 86° and 96 ,
respectively.

246 ORGANIC CHEMISTRY.

DERIVATIVES OF THE ACIDS.
I. THE ACID HALOIDS.

The haloid anhydrides of the acids (or acid haloids) are those
derivatives which arise in the replacement of the hydroxyl of acids
by halogens ; they are the halogen compounds of the acid radicals
(p. 213). Their most common method of formation consists in
letting the phosphorus haloids act upon the acids or their salts — ^just
as the alkylogens are produced from the alcohols (p. 92).

(i) At ordinary temperatures phosphorus pentachloride acts very energetically
upon the acids : —

C2H3O.OH + PCI5 = C2H3O.CI + POCI3 + HCl.

The product of the reaction is subjected to fractional distillation. It is better
to have FCI3 act upon the alkali salts or the free acids; heat is then not neces-
sary : —

3C2H3O.OK + PCI3 = 3C2H3O.CI + PO3K3.

By this method the pure acid chloride is at once obtained in the distillate —
while the phosphite remains as residue. Or, phosphorus oxychloride (i molecule)
may be permitted to act on the dry alkali salt (2 molecules) when a m'etaphosphate
will remain : —

2C2H30.0Na + POCI3 = 2C2H3O.CI + POjNa + NaCl.

Should there be an excess of the salt, the acid will also act upQn it and acid anhy-
drides result (p. 248).

Phosphorus bromides behave similarly. A mixture of amorphous phosphorus
and bromine may be employed as a substitute for the prepared bromide (p. 95).
Phosphorus iodide will not convert the acids into iodides of the acid radicals ;
this only occurs when the acid anhydrides are employed.

(2) Carbon oxychloride acts upon the free acids and their salts the same as the
chlorides of phosphorus. Acid chlorides and anhydrides are produced. This
method has met with technical application {Berichte, 17, 1285; 21, 1267) : —

C2H3O.OH + COClj =. C2H3OCI + CO2 + HCl.

(3) An interesting method for preparing the acid bromides consists in letting
air act upon certain bromide derivatives of the alkylens, whereby oxygen will be
absorbed. Thus, from CBrjiCHj we obtain bromacetyl bromide, CHjBr.COBr;
from CBrjrCHBr, dibromacetyl bromide, CBr^H.COBr (p. 97 and Berichte, 13,
1980; 21,3356).

The acid haloids are sharp-smelling liquids, which fume in the
air, because of their transformation into acids and halogen hydrides.
They are heavier than water, sink in it, and at ordinary tempera-
tures decompose, forming acids : — ' '

C2H3O.CI + HjjO = CJH3O.OH + HCl.

The more readily soluble the resulting acid is in water, the more
energetic will the reaction be.

ACID CYANIDES. 247

The acid chlorides act similarly upon many other bodies. They
yield compound ethers, or esters, with the alcohols or alcoholates
(p. 251). With salts or acids they yield acid anhydrides (p. 248),
and with ammonia, the amides of the acids, etc.

Sodium amalgam, or better, sodium and alcohol, will convert the
acid chlorides into aldehydes and alcohols (pp. 122 and 188). They
yield ketones and tertiary alcohols when treated with the zinc alkyls
(pp. 200 and 120).

Acetyl Chloride, C^HjOCl = CH3.CO.CI, is produced also by
the action of hydrogen chloride and phosphorus pentoxide upon
acetic acid, and when chlorine acts on aldehyde. It is a colorless,
pungent-smelling liquid which boils at 55°, and has a specific gravity
of 1. 130 at 0°. Water decomposes it very energetically.

Preparation. — Bring PCI5 into a retort with a tubulure, and through the latter
gradually add anhydrous acetic acid. After the first violent action, apply heat and
fractionate the distillate. It would be better to distil carefully a mixture of acetic
acid (3 parts) and PCI3 (2 parts). Or, heat POCI3 (2 moleculesj with acetic acid
(3 molecules), as long as HCl escapes, then distil [Annalen, 175, 378). The
acetyl chloride is purified by again distilling over a little dry sodium acetate.

Acetyl chloride forms the following substitution products with chlorine :
C^HjClO.Cl, boiling at 106°; C^HCIjO.Cl and CjCljO.Cl; the latter boil at 118°.
These are also obtained when phosphorus chloride acts on the substituted acetic
acids. Monobromacetyl chloride, CjHjBrO.Cl, boils at 134°.

Acetyl Bromide, C2H3O.Br, boils at 81° and forms substitution products with
bromine. Monochloracetyl Bromide, C^H^ClO.Br, from monochloracetic acid,
boils at 134°.

Acetyl Iodide, CjlIjO.!, is obtained by letting I and P act upon acetic an-
hydride. It boils at 108° and is colored brown by separated iodine.

Propionyl Chloride, CHj.CHj.CO.Cl, boils at 80°; the bromide, C3H5O.Br,
at 97°, and the iodide, C3H5O.I, at 127°.

Butyryl Chloride, C^H,O.Cl,from normal butyric acid, boils at 101°. Sodium
amalgam converts it into normal' butyl alcohol. Isobutyryl Chloride, (CH3)2.
CH.CO.CI, boils at 92°.

Isovaleryl Chloride, CjHgO.Cl, from isovaleric acid, boils at 115°.

2. ACID CYANIDES.

When the chlorides of the acid radicals are heated with silver cyanide, cyanides
of the acid radicals, like acetyl cyanide, CH3.CO.CN, result. They can also be
obtained by the action of dehydrating agents, e. g., acetic anhydride upon isonitroso-
ketones {Berichte, 20, 2196) : —

CH3.C0.CH:N.0H = CH3.CO.CN + H^O.

Water or alkalies will readily convert these into their corresponding acids and
hydrogen cyanide, CH3.CO.CN -|- H^O = CH3.CO.OH + CNH. With con-

248 ORGANIC CHEMISTRY.

centrated hydrochloric acid, on the contrary, they sustain a transposition similar
to that of the alkyl cyanides (p. 211), i. e., carboxyl derivatives of the acid radi-
cals— the so-called a-ketonic acids (see these) — are produced : —

CH3.CO.CN -f 2H2O 4- HCI = CH3.CO.CO2H -I- NH4CI.

Acetyl Cyanide, CH3.CO.CN, boils at 93°. When preserved for some time,
or by the action of KOH or sodium, it is transformed into a polymeric, crystalline
compound, (C2H30CN)2, diacetyl cyanide. This melts at 69° and boils at 208°.
Concentrated hydrochloric acid converts it into pyroracemic acid.

Diacetyl cyanide is also produced by the action of potassium cyanide upon acetic
anhydride [Berichte, 18, 256).

Propionyl Cyanide, CHj.CH^.CO.CN, from propionyl chloride, boils at 108-
110°. Dipropionyl Cyanide, (C3H50.CN)2, formed by the action of silver
cyanide upon propionyl bromide, melts at 59°, and boils at 200-210° {^Berichte,
i8,Ref. 140). ButyrylCyamde,C3H,.CO.CN,boilsat 133-137°; isobutyryl •
"■, at 118-120°. These polymerize readily to dicyanides.

3. ACID ANHYDRIDES AND PEROXIDES.

The acid anhydrides are the oxides of the acid radicals. In those
of the monobasic acids two acid radicals are united by an oxygen
atom ; they are analogous to the oxides of the monovalent alcohol
radicals — the ethers. They cannot, however, be made by the
direct withdrawal of water from the acids. Anhydrides do indeed
result by the action of P2O5, but their quantity is very small. The
following methods are employed in their preparation : —

(i) The chlorides of the acid radicals are allowed to act on anhy-
drous salts, viz., the alkali salts of the acids :—

CjjHjO.OK -I- C2H3O.CI = c^H^O/*-* + ■''^^'•

The simple anhydrides, those containing two similar radicals, can as a general
thing be distilled, while the mixed anhydrides, with two dissimilar radicals, decom-
pose when thus treated, into two simple anhydrides : —

C2H30\q _ C^Yi,0\ C^H.OXq

C,H,0/*^ - C2H3O/" + C^HgO/*^-

Hence they are not separated from the product of the reaction by distillation, but
are dissolved out with ether.

A direct conversion of the acid chlorides into the corresponding anhydrides may
be effected by permitting the former to act upon anhydrous oxalic acid {^Annalen,
226, 14): —

2C2H3OCI + C.O^H^ = (C2H302)0 + 2HCI + CO, -f CO.

(2) Phosphorus oxychloride (i molecule) acts upon the dry
alkali salts of the acids (4 molecules). The reaction is essentially

ACID ANHYDRIDES AND PEROXIDES. 249

the same as the first. The acid chloride which appears in the
beginning acts immediately upon the excess of salt: —

2C2H3O.OK + POCI3 . =2C,H30.C1 + PO3K + KCl, and
C.HaO.OK + C.HeO.Cl = (C,H30)20 + KCl.

Phosgene, COCl^, acts like POCI3. In this reaction acid chlorides are also
produced.

The anhydrides of the fatty acids can be produced further by the action of acetyl
chloride on the latter ^ Berichte, 10, 1881).

The acid anhydrides are liquids or solids of neutral reaction,
and are soluble in ether. Water decomposes them into their
constituent acids : —

(C2H30)20 + H^O = 2C3H3O.OH.

With alcohols they yield the acid esters (p. 251) : —

{C^nfi)^0 + C2H5.OH = ^^^^°^0 + C,H30.0H.

Chlorine splits them up into acid chlorides and chlorinated
acids : —

(C^-S-fi^j^O + CI2 = C2H3O.CI + C2H3CIO.OH.

Heated with hydrochloric acid they decompose into an acid
chloride and free acid : —

(C2H30)aO + HCl = C2H3O.CI f C2H3O.OH.

HBr and HI act similarly. As the heat modulus is positive in this reaction, the
reverse reaction (action of acid chloride upon the acid) is generally not adapted
to the formation of anhydrides (compare Annalen, 226, 5).

Acetic Anhydride — Acetyl Oxide, (CjHaO)^©, is a mobile
liquid boiling at 137°. Its specific gravity equals 1.073 ^' °°-

To prepare it, distil a mixture of anhydrous sodium acetate (3 parts) with
phosphorus oxychloride (l part) ; or, better, employ equal quantities of the salt
and acetyl chloride. The distillate is redistilled over sodium acetate, to entirely
free it from chloride.

Nascent hydrogen converts it first into aldehyde and then into
alcohol (p. 188).

Propionic Anhydride or Propionyl Oxide, (CjHsOjjO, boils at 168°. Bu-
tyric Anhydride, (C4^H,0)a, boils near 190°; its specific gravity = 0.978 at
21

250 ORGANIC CHEMISTRY.

12.5°. Isovaleric Anhydride, {C^Hfi)fi, boils with partial decomposition
about 215°. Its specific gravity at 15° equals 0.934. It possesses an odor like
that of apples.

The higher anhydrides do not volatilize virithout undergoing decomposition.
Caprylic Anhydride, (CjHi 50)20, melts at '0°. Myristic Anhydride, [C^^
H2,0)20, forms a fatty mass, fusing at 54°.

The peroxides of the acid radicals are produced on digesting the chlorides or
anhydrides in ethereal solution vfith barium peroxide: —

2C2H3O.CI + BaOj = {C^iifi)fi^ + BaClj.

Acetyl Peroxide is a thick liquid, insoluble in water, but readily dissolved by
alcohol and ether; It is a powerful oxidizing ^ent, separating iodine from potas-
sium iodide solutions, and decolorizing a solution of indigo. Sunlight decomposes
it, and when heated it explodes violently. With barium hydroxide it yields
barium acetate and barium peroxide.

4. THIO-ACIDS AND THIO-ANHYDRIDES.

The thio-acids, e.g., thio-acetic acid, CH3.CO.SH, correspond
to the thio-alcohols or mercaj)tans (p. 140), and are produced by
analogous methods : by the action of acid chlorides upon potassium
sulphydrate, KSH, and by heating acids with phosphorus penta-
sulphide : —

SC2H3O.OH + V,S, = 5C2H3O.SH + P2O5.

The thio-anhydrides arise in the same manner by the action of
phosphorus sulphide upon the acid anhydrides.

The thio-acids are disagreeably-smelling liquids, more insoluble
in water and possessing lower boiling temperatures than the corre-
sponding oxygen acids. Like the latter, they yield salts and esters.
When heated with dilute mineral acids they break up into H^S and
fatty acids. Water slowly decomposes the thio-anhydrides into a
thio-acid and an oxy-acid.

The esters are obtained when the alkylogens react with the salts of the thio-
acids, and by letting the acid chlorides act upon the mercaptans or mercaptides : —

C2H3O.CI + CjHj.SNa = C2H3O.S.C2H5 + NaCl.

They also appear in the decomposition of alkylic isothio-acetanilides with dilute
hydrochloric acid : —

CH3.c/|^(5^^s^ -f H2O = CH3.CO.S.C2H5 -f NH,.C3H5.
Ethyl-isothio-acetanilide. Thioacetic Ester. Aniline.

ESTERS OF THE FATTY ACIDS. 25 1

Concentrated potash resolves the esters into fatty acids and mercaptans.

Thiacetic Acid, CjHjO.SH, is a colorless liquid, boiling at 93°, and having
a specific gravity of 1.074 at 10°. Its odor resembles that of acetic acid and hydro-
gen sulphide. It is sparingly soluble in water, but dissolves readily in alcohol and
ether. The lead salt, (C2H30.S)2Pb, crystallizes in delicate needles, and readily
decomposes with formation of lead sulphide. Ethyl Thiacetate, C^HjO.S.CjHj,
boils at 115°.

Acetyl Sulphide, (€21130)28, is a heavy, yellow liquid, insoluble in water;
and is slowly decomposed by this liquid into acetic acid and thiacetic acid. It
boils at 121°.

Acetyl Disulphide, (€21130)282, is produced when acetyl chloride acts upon
potassium disulphide, or iodine upon salts of the thio-acids : —

2C2H30.8Na + 12 = (C2H30)2S2 + 2NaI.

5. E8TER8 OF THE FATTY ACID8.

The esters of organic acids resemble those of the mineral acids in
all respects (p. 146), and are prepared by analogous methods: —

(i) By the action of acid chlorides (or acid anhydrides, p. 246)
on the alcohols or alcoholates : —

C2H3O.CI + C2H5.OH = ^2^3 0->o + HCl.

Transpositions frequently occur when alcoholates are used, for example, when
ethyl ester is converted into a methyl ester by the action of methyl sodium. It is
also true in the reverse case [Berichte, 20, ISS4)-'

(2) By the action of the alkylogens upon salts of the acids: —

C2H5CI + CjHjO.ONa = ^^Hs O^q ^ j^^^^^j

(3) By the dry distillation of a mixture of the alkali salts of the
fatty acids and salts of alkyl sulphates (p. 149) : —

SO

^O K^"' + C.H3O.OK = S0,K2 + l^^^ o>0.

2\0.K

(4) By direct action of acids and alcohols, whereby water is
formed at the same time : —

C2H5.OH + C2H3O.OH = C2H5.O.C2H3O + H2O.

This transposition, as already stated, only takes place slowly
(p. 147); heat hastens it,' but it is never complete. If a mixture
of like equivalents of alcohol and acid be employed, there will
occur a time in the action when a condition of equilibrium will
prevail, when the ester formation will cease, and both acid and
alcohol will be simultaneously present in the mixture. This ensues.

252 ORGANIC CHEMISTRY.

because the heat modulus of the reaction is very slight, and hence,
in accordance with the principles of thermo-chemistry, and under
slightly modified conditions, the reaction pursues a reverse course,
/. e., the ester is decomposed by more water into alcohol and acid,
since heat is generated when they are dissolved by the water. Both
reactions mutually limit themselves. With excess of alcohol, more
acid can be changed to ester, and with excess of acid more alcohol.
The formation of the esters is more complete and rapid, if the re-
action products are assiduously withdrawn from the mixture. This
may be effected either by distillation (providing the ester is readily
volatilized), or by combining the water formed with sulphuric or
hydrochloric acid, when the heat modulus will be appreciably aug-
mented.* We practically have from the above the following
methods of preparation. Distil the mixture of the acid or its salt
with alcohol and sulphuric acid. Or, when the esters volatilize with
difficulty, the acid or its salt is dissolved in excess of alcohol (or
the alcohol in the acid), and while applying heat, HCl gas is con-
ducted into the mixture (or H2SO4 added), and the ester precipi-
tated by the addition of water. The acid nitriles can be directly
converted into esters, by dissolving them in alcohol, and heating
them with dilute sulphuric acid (p. 211).

Berthelot has executed more extended investigations upon the ester formation.
These are of great importance to chemical dynamics. He observe^, for instance,
that the reaction is materially accelerated by heat, but that a limit to the ester
production invariably occurs, and that it equals that of the reverse transposition
of the esters by water. This limiting point is independent of the speed of the
reaction and temperature, but is controlled by the relative quantities, as well as
the nature of the alcohol and acid. According to Berthelot the speed of the ester
formation in the case of the primary normal alcohols is almost the same; the
degree of the conversion or transposition equals about 66 per cent, of the mix-
ture (with equivalent quantities of alcohol and acid). Proceeding from the simple
assumption that the quantities of alcohol and acid combining in a unit of time
(speed of reaction) are proportional to the product of the reacting masses, whose
quantity regularly diminishes, Berthelot has proposed a formula (Annalen chim.
phis,, 1862) by which the speed of the reaction in every moment of time, and its
extent, can 'be calculated, van't Hoff has deduced a similar formula {^Berickte,
10, 669), which Guldberg-Waage and Thomsen pronounce available for all lim-
ited reactions (ibid, 10, 1023). For a tabulation of the various calculations relating
to this matter, see Berichte, 17, 2177; ig, 1700. Of late Menschutkin has ex-
tended the investigations upon ester formations to the several homologous series of
acids and alcohols (^««3/i?«, 195, 334 and 197, 193; Berichte, 15, 1445 and
1572; 21, Ref. 41).

Usually the esters of fatty acids are volatile, neutral liquids, sol-
uble in alcohol and ether, but generally insoluble in water. Heated
with the latter they sustain a partial decomposition into alcohol and

* Consult Annalen, 211, 208.

ESTERS OF FORMIC .ACID. 253

acid. This decomposition {saponification) is more rapid and com-
plete on heating with alkalies in alcoholic solution : —

qHaO.O.CjHs + KOH = C^HjCOK + C^H^.OH.

Consult Annalen, 228, 257, and 232, 103 ; Berichte, 20, 1634, upon the velocity
of saponification by various bases.

Ammonia changes the esters into amides (p. 256) :

C.HjO.O.C.H, +NH3=C,H3.0.NH2 +C2H5.OH.
icids convert the esters into acids and haloid-esters (

C^HjO.O.C^Hg + HI = C.H^O.OH + C,H.,I.

The haloid acids convert the esters into acids and haloid-esters (Annalen, 211
178):—

PCI5 introduces chlorine, and the radicals are converted into halogen deriva-
tives : —

CjHjO.O.C.H^ -f PCI5 = C^HjO.Cl + C2H5CI + POClg.

The esters of the fatty acids possess an agreeable fruity odor, are
prepared in large quantities, and find extended application as arti-
ficial fruit essences. Nearly all fruit-odors may be made by mixing
the different esters. The esters of the higher fatty acids occur in
the natural varieties of wax.*

ESTERS OF FORMIC ACID.

Methyl Formic Ester, CHOj.CHj, is obtained by distilling sodium formate
with sodium methyl sulphate, or more advantageously by adding methyl alcohol
(13 parts) saturated with HCl-gas to calcium formate (10 parts) and then distil-
ling. Another course consists in conducting HCl into a mixture of formic acid
and alcohol, and then distilling. A mobile, agreeably-smelling liquid, that boils at
32.5° and has a specific gravity of 0.9984 at 0°. In sunlight chlorine produces
Perchlor-methyl formic ester, CClOj.CClj, which boils at 180-185°. Heated
to 305° it breaks up into carbonyl chloride, CjCl^O^ = 2COCI2. Aluminium
chloride converts it into CCI4 and COj.

Ethyl Formic Ester, CHO^.C^Hj, boils at 54.4° and dissolves in 10 parts
water. Its specific gravity equals 0.9445. To prepare it, distil a mixture of dry
sodium formate (7 parts), sulphuric acid (10 parts), and 90 per cent, alcohol (6
parts). It is better to heat a mixture of oxalic acid, glycerol and alcohol in a
flask with a return cooler, until the evolution of carbon dioxide ceases, then distil
off the ester; at first a glycerol ester of formic acid is produced (p. 217), which
the alcohol decomposes.

The above ester serves in the manufacture of artificial rum and arrack.

The propyl ester, CHO2.C3H,, boils at 8l°. The butyl ester, CYiO^.C^^,
boils at 107°. The normal amyl ester boils at 130.4°. Isoamyl ester, CHOj.
CjHji, has a fruity odor and boils at 123°.

The allyl ester, CHOj.CgHj, is formed on heating oxalic acid with glycerol,
and boils at 82-83° (P- 134)-

For higher esters consult Annalen, 233, 253.

* Ueber die Siedepunkte der Fettsaureester und ihre spec. Gewichte s. Be-
richte, 14, 1274 u. Annalen, 218, 337. Ueber die specif. Volumen. s. Annalen,
220, 290 u. 319; Annalen, 223, 249.

254 ORGANIC CHEMISTRY.

ESTERS OF ACETIC ACID.

The Methyl Ester, Methyl Acetate, C2H3O2.CH3, occurs in crude wood-
spirit, boils at 57.5°, and has n specific gravity of 0.9577 at 0°. When chlorine
acts upon it the alcohol radical is first substituted: CjHjOj.CHjCl boils at 150°;
CjHjOj.CHClj boils at 148°.

The Ethyl Ester, Ethyl Acetate— Acetic Ether— C2H3O2.C2H5, is a liquid
with refreshing odor, and boils at 77°- At 0° its sp. gr. equals 0.9238. It dis-
solves in 14 parts water, and readily decomposes into acetic acid and alcohol. In
preparing it, heat a mixture of 100 c.c. HjSO^ and 100 c c. alcohol to 140°, and
gradually run in a mixture of i litre alcohol (95°) and i litre acetic acid {£e-
richte, 16, 1227). The distillate is shaken with a concentrated solution of salt, to
withdraw all alcohol, the ether is siphoned off, dehydrated over calcium chloride,
and finally rectified.

Chlorine produces substitution products of the alcohol radicals. Sodium dis-
solves in the anhydrous ester, forming sodium aceto-acetic ester. The propyl ester,
CjHjOj.CjH,, boils at 101°; sp. gr. 0.9091 at 0°. The isopropyl ester boils at
91°.

The butyl ester, CjHjOj.CiHg, is obtained from normal butyl alcohol. It boils
at 124°. The ester of primary isobutyl alcohol boils at 116°; that of the second-
ary alcohol at 1 1 1°, and that of the tertiary at 96°.

Amyl Esters, C^fi,^.Q^^.^. The ester of normal amyl alcohol boils at
148°; that of propyl-methyl carbinol at 133°, and that of isopropyl methyl carbinol
at 125°. At 200° it splits up into amylene and acetic acid. The acetic ester
of amyl alcohol of fermentation (p. 130) boils at 140°- A dilute alcoholic solu-
tion of it has the odor of pears and is used as pear oil.

Hexyl acetic ester, CjHjOj-CgHig, with the normal hexyl group, occurs in
the oil of Heracleum. giganteum. It boils at 169-170° and possesses a fruit-like
odor.. The octyl ester, C^HgOj.CgHj,, is also present in the oil of Heracleum
giganteum. It boils at 207° and has the odor of oranges.

The allyl-ester, CjHjO.O.CjHj, obtained from allyl iodide, boils at 98-100°.

Consult Annalen, 233, 260 for higher acetic acid esters.

ESTERS OF PROPIONIC ACID.

The methyl ester, C3H5O2.CH3, boils at 79.5°. The ethyl ester, C3H5O2.
CjHj, boils at 98°. The propyl ester, C3H5O2.C3H,, boils at 122° ; the isobutyl
ester, CgH^O^.C^Hg, at 137°; and the isoamyl ester, C3H5O2.C5HJ1, at 160°;
the latter has an odor like that of pine-apples. (See Annalen, 233, 265.)

ESTERS OF THE BUTYRIC ACIDS.

Methyl Butyric Ester, C4H,02.CH3, boils at 102.3°. The ethyl ester,
C^HjOj.CjHj, boils at 120.9°, has a pine-apple-like odor, and is employed in
the manufacture of artificial rum. Its alcoholic solution is the artificial /««?-«///«
oil. This is prepared on a large scale by saponifying butter with sodium hydroxide
and distilling the sodium salt which is formed with alcohol and sulphuric acid.

The normal propyl ester, C^HjOj.CjH,, boils at 143° ; the isopropyl ester,
C4H,Oj.C3H„ at 128°. The isobutyl ester, C^f).,.Q.^^, boils at 157°. The
isoamyl ester, C4H,02.C5H,j, boils at 178°, and its odor resembles that of pears.
The hexyl ester and octyl ester are found in the oil obtained from various species
of Heracleum (see above). See, also, Annalen, 233, 271.

Ethyl Isobutyric Ester, C^HyO^.C^Hj, boils at 110°.

ACID AMIDES. 255

The esters of the higher acids, as well as those of the substituted acids, are
mostly mentioned along with the latter. We may yet notice here : —

Isoamyl Isovaleric Ester, CjHgOj.CjH,!, boils at 196°, and is obtained by
direct oxidation of the amyl alcohol of fermentation. Its odor is very much like
that of apples, and it finds application under the name apple oil.

See Annalen 233, 273-290, for esters of hexoic, heptoic, valeric and octoic acids.

The complex esters, having high molecular weights, are solids, and cannot be
distilled without suffering decomposition. Thus cetyl acetic ester, CjHjOj.CjjHjj,
melts at 18.5° ; ethyl palmitic ester, CjjHjiOj.C^H^, at 24°. These esters are pre-
pared by dissolving the acid in alcohol, or the latter in the acid, and then satu-
rating the solution with HCl (p. 252). The esters with high alkyls break up into
defines and fatty acids (p. 80) when distilled under pressure.

Some of the higher esters occur already formed in waxes and in
spermaceti.

Spermaceti {^Cetaceum, Sperma Ceti) occurs in the oil from pecu-
liar cavities in the head of whales (particularly Physeter macro-
cephalus), and upon standing and cooling it separates as a white
crystalline mass, which can be purified by pressing and recrystal-
lization from alcohol. It consists of Cetyl Palmitic Ester,
CifiHsiO^. CisHss, which crystallizes from hot alcohol in waxy, shin-
ing needles or leaflets, and melts at 49°. It volatilizes undecom-
posed in a vacuum. Distilled under pressure, it yields hexadecy-
lene and palmitic acid. When boiled with caustic potash it
becomes palmitic acid and cetyl alcohol.

Chinese wax is Ceryl Cerotic Ester, CjjHjjOj.C^jHjj. Alcoholic potash de-
composes it into cerotic acid and ceryl alcohol.

Ordinary beeswax is a mixture of cerotic acid, CjjHjjOj, with Myricyl
Palmitic Ester, C,5H3i02.Cg|,H5i. Boiling alcohol extracts tfie cerotic acid and
the ester remains. Annalen, 224, 225.

Beeswax further contains the two hydrocarbons Heptacosane, CjjHjj, and
Hentriacontane, CjjHj^, in addition to several alcohols, from C^sHjjO to
C31H84O {Annalen, 235, 106).

Carnauba wax, from the leaves of the carnuba tree, melts at 83°- It contains
free ceryl alcohol, and various acid esters (Annalen, 223, 283).

6. ACID AMIDES.

These correspond to the amines of the alcohol radicals (p. 157).
The hydrogen of amtnonia can be replaced by acid radicals forming
primary, secondary and tertiary amides.

The following general methods for preparing primary amides are
in use : —

ZS6 ORGANIC CHEMISTRY.

1. The action of acid chlorides upon aqueous ammonia: —

C2H3O.CI + 2NH3 = C2H3O.NH2 + NH^Cl.

Acetamide.

This method is especially adapted to the higher fatty acids {Be-
richte, 15, 1728). If amine bases be substituted for ammonia, mixed
amides result : —

C3H3O.CI + C.Hj.NH, =c'^H30>^^ + ■"^'-

Ethylamine. Ethyl Acetamide.

The acid anhydrides have a similar action upon ammonia and
the amines : —

(C2H30)20 + 2 NH3 = C2H3O.NH, + C3H30.0.NH^.

Acetic Anhydride. Acetamide,

2. The action of ammonia or amines upon the esters — a reaction
that frequently takes place in the cold ; it is best, however, to apply
heat to the alcoholic solution : —

C^HjO.O.C.Hj + NHj =C,H30.NH, + C^H^.OH,

Acetamide.

C2H30.0.C,H5 + C^Hs.NH^ = ^^^^^'^ >NH + C^H^.OH.

Ethyl Acetamide.

This is one of the so-called reversible reactions, inasmuch as the action of alco-
hols upon acid amides again produces esters and ammonia [Berichte, 22, 24).

3. The dry distillation of the ammonium salts of the acids of
this series. This procedure is adapted to the preparation of vola-
tile amides. A mixture of the sodium salts and ammonium chloride
may be substituted for the ammonium salts ; the latter will be pro-
duced at first : —

C^HjO.O.NHi = C2H3O.NH2 + H^O.

Ammonium Acetate. Acetamide.

A more abundant yield is obtained by merely heating the ammo-
nium salts to about 230° {Berichte, 15, 979). Consult Berichte,
17, 848, upon the velocity and limit of the amide production.

4. The distillation of the fatty acids with potassium sulphocyanide : —

2C2H3O.OH -I- CN.SK = qHjO.NHj + CjHjO.OK -f COS.

Simply heating the mixture is more practical [Berichte, 16, 2291, and 15, 978).
In this reaction the aromatic acids yield nitriles.

5. The addition of i molecule of water to the, nitriles of the
acids (cyanides of the alcohol radicals) : —

CH3.CN + HjO = CH3.CO.NH2.

Acetonitrile. Acetamide.

AMIDES. 257

This conversion is often accomplished by acting in the cold with concentrated
hydrochloric acid, or by mixing the nitrile with glacial acetic acid and concen-
trated sulphuric acid (Berichte, 10, 1061). Hydrogen peroxide will also convert
the nitriles, with oxygen liberation, into the amides (Berichte, 18, 7.'!,c,\ : R CN -4-
2H20, = R.CO.NH, + H,0 + 0,. ' '^"^ ^

The preceding methods are not applicable in the preparation of secondary and
tertiary amides, as the acid chlorides do not generally act on the primary amides.
They are obtained by heating the alkyl cyanides (the nitriles) with acids, or acid
anhydrides, to 200° : —

CH3.CN + CH3.CO.OH = ch' CO/^^'
Methyl Cyanide. Acetic Acid. Diacetamide.

CH3.CN + (CH3.CO)20 = (CH3.CO)3N.
Acetic Anhydride. Triacetamide.

The secondary amides can also be prepared by heating primary amides with dry
hydrogen chloride : —

2CJH3O.NH2 + HCl = (C2H30)2NH + NH^CI.

Diacetamide.

Mixed amides, which at the same time contain alcohol radicals, are further pro-
duced by the action of esters of ordinary isocyanic acid upon acids or acid anhy-
drides : —

CO:N.C,H5 + C2H3O.OH = ^^HsOXnh -f CO^,
' Ethyllsocyanate. '-'Z^s/

COiN.C^H, + (C,H30),0 = ^^g^°^N.C,H, -^ CO,.

Ethyl Diacetamide.

The amides of the fatty acids are usually solid, crystalline bodies,
soluble in both alcohol and ether. The lower members are also
soluble in water, and can be distilled without decomposition. As
they contain the basic amido-group they are able to unite directly
with acids, forming salt-like derivatives {e.g., C2H3O.NH2.NO3H),
but these are not very stable, because the basic character of the
amido-group is strongly neutralized by the acid radical. Further-
more, the acid radical 'imparts to the NHj-group the power of ex-
changing a hydrogen atom with metals not very basic, forming
metallic derivatives, e.g., (CH3.C0.NH)j.Hg — mercury acetamide,
analogous to the isocyanates (from isocyanic acid, CO:NH).

The union of the amido-group with the acid radicals (the group
CO) is very* feeble in comparison with its union with the alkyls in
the amines (p. 158). The amides, therefore, readily decompose
into their components. Heating with water effects this, although
it is more easily accomplished by boiling with alkalies or acids : —

CH3.CO.NH2 -I- H2O = CH3.CO.OH + NH3.
22

258 ORGANIC CHEMISTRY.

Nitrous acid decomposes the primary amides similarly (p. 161),
whereby the ammonia breaks up with the evolution of nitrogen and
the formation of water : —

C2H3O.NH2 + NO^H = CjHsO.OH + N2 + H^O.

Bromine in alkaline solution changes the primary amides to
brom-araides {^Berichte, 15, 407 and 752) : —

C2H3O.NH2 + Br^ = CjHjO.NHBr + HBr,

which then form amines (p. 160). On heating with phosphorus
pentoxide, or with the chloride, they part with i molecule of water
and become nitriles (cyanides of the alcohol radicals) : —

CH3.CO.NH2 = CHj.CN + HjO.

In this action a replacement of an oxygen atom by two chlorine
atoms takes place; the resulting chlorides, like CH3.CCI2.NH2,
then lose, upon further heating, 2 molecules of CIH with the forma-
tion of nitriles : —

CH3.CCI2.NH2 = CH3.CN + 2HCI.

In the mixed amides, containing an alcohol radical besides the acid .radical in
the amido-group, PCI5 effects a similar substitution of 2CI for an oxygen atom.
The products are the so-called amid-chlorides, which readily part with HCl and
become imid-chlorides : —

CH3.CCl2.NH(C2H5) = CH3.CC1:N(C2H5) + HCl.

These regenerate the amides with water :—CH3.CCl:N(C2H5) + H^O = CH3.
CO.NH(C2H5) -\- HCl. When heated they lose, however, hydrochloric acid
and yield chlorinated bases : —

2CH3.CC1:N(C2H3) = C^HijClN^ + HCl.

The chlorine in the imid-chlorides is very reactive; the action of ammonia on
amines produces the amidines (see these) : —

CH3CC1:N(C,H,) + NH^.C^H, = CH3.C^^j^^(Pfj^ -f HCl.

Hydrogen sulphide converts them into thio-amides.

The chlorimides, containing the group NCI, but only known in the benzene
series, are isomeric with the imid-chlorides, RN:CC1. They can be converted
into the latter by a molecular rearrangement (see Benzoanilide, Berichte, 19, 992).

AMIDES.

259

Formamide, CHO.NHj, the amide of formic acid, is obtained
by heating ammonium formate to 230°, or ethyl formic ester with
alcoholic ammonia to 100° {Berichte, 15, 980) ; also by boiling
formic acid with ammonium sulphocyanide {Berichte 16, 2291).
It is a liquid, readily soluble in water and alcohol, and boils with
partial decomposition at i92°-i95°. Heated rapidly, it breaks up
into CO and NH3 ; P^Oj liberates HCN from it.

Mercuric oxide dissolves in it with the formation of mercury formamide,
(CHO.NHjjHg, This is a feebly alkaline liquid, sometimes applied as a subcu-
taneous injection.

Ethyl Formamide, CHO.NH.C^Hj, is obtained from ethyl formic ester and
ethylamine ; also by distilling a mixture of the latter with chloral : —

CCI3.CHO + NH2.C2H5 = CHO.NH.C^Hs + CCljH.

It boils at 199°.

Acetamide, C2H3O.NH2, is produced on heating a mixture of
dry sodium acetate and ammonium chloride, or by digesting acetic
ester with alcoholic ammonia {Berichte, 15, 980). Another method
consists in supersaturating glacial acetic acid with ammonia, and
then distilling in a current of ammonia {Berichte, 18, Ref. 436).
It crystallizes in long needles, melts at 82-83°, and boils at 222°
undecomposed. It dissolves with ease in water and alcohol, and
when boiled with alkalies or acids, passes into acetic acid and
ammonia. With acids, it forms unstable compounds, like QHjNO.
NO3H and (C2H5N0)2.HC1. When the aqueous solution is boiled
with mercuric oxide, the lattef dissolves, and on cooling mercury
acetamide, (C2H30.NH)2Hg, separates (p. 257).

Acetbromamide, C^HjO.NHBr (p. 258), crystallizes from water and ether with
I molecule HjO, in large plates, and melts in an anhydrous condition at 108°.

Substituted acetamides are derived from substituted acetic esters by the action
of alcoholic ammonia, and evaporation at ordinary temperatures. Chloracetamide,
C2H2CIO.NH2, melts at 116°, and boils at 224°-225°. Dichloraceiaviide,
CjHClgO.NHj, njelts at 96°, and boils at 233°-234°. Trichloracetamide melts
at 136°, and boils at 238°-239°

Diacetarriide, (C2H30)2NH, obtained by heating acetamide in a stream of
HCl (p. 257), is readily soluble in water, fuses at 59°, and boils at 2Io°-2IS°.

Triacetamide, (C2H30)3N, is prepared by heating acetonitrile (methyl
cyanide) with acetic anhydride to 200° (p. 257). It melts at 78°-79°.

Propionamide, CjHjO.NHj, is similar to acetamide, melts at 75° and boils
at 210°.

Butyramide, C^HjO.NHj, crystallizes in leaflets, fusing at 115° and boiling
at 216°. Isobutyramide fuses at 129°.

Isovaleramide, CsHgO.NHj, from valeric acid, sublimes in leaflets, soluble
in water and fusing at 126°.

Lauramide, C,2H230.NH2, fuses at 102°; Myristamide, Ci^HjjO.NHj,
at 104°; Palmitamide, Ci6H3iO.NH2,at 107°; Stearamide.Ci jHgsO.NHj,

26o ORGANIC CHEMISTRY.

at 109° (Berichte, 15, 984 and 15, 1728). These higher amides may also be
prepared by saponifying the fats with alcoholic ammonia, when the glycerol esters
will react, in a manner similar to that of the monohydric alcohols.

Hydroxamic Acids.

These are produced when free hydroxylamine, or its hydrochloride, is allowed
to act upon acid amides. They contain the isonitroso-group in the place of the
carbonyl oxygen {Berichte, 22, 2854) : —

CH3.CO.NH2 + NH2.OH = CHj.C^Q^^ + NH3.

Ethyi-hydroxamic Acid.

They are crystalline compounds, acid in character, and form an insoluble copper
salt in ammoniacal copper solutions. Ferric chloride imparts a cherry-red color to
both their acid and neutral solutions.

Ethyl Hydroxamic Acid, CH3.C(N.0H).0H, with ^^HjO, is a crystalline
hydrate, melting at 59°. It dissolves very easily in water and alcohol, but not in
ether. Compare Benzhydroxamic acid.

7. THIO-AMIDES.

Thio-amides of the acids, e.g., thio-acetamide, CH3.CS.NH2, and thio-benza-
mide, C5H5.CS.NH2, are formed by letting phosphorus sulphide act upon the
acid amides (p. 250), and by the addition of H^S to the nitriles : —

CH3.CN + HjS = CH3.CS.NH2.
Acetonitrile. Thio-acetamide.

Phenyl thio-amides, in which the H of the amido-group is replaced by C3H5,
e.g., thio-acetanilide, CH3.CS.NH.C5H5, are obtained from the anilides (see
these) by the action of PjSj ; also by acting with HjS upon the amid-chlorides,
imid-chlorides, and amidines, and by treating the latter with CSj {Berichte, 22,
506). The thio-anilides of formic acid, thio-formanilides, result by the addition
of HjS to the isonitriles or isocyanides (of the benzene series) : —

C2H5.NC -I-H2S = C^Hj.NH.CHS.
Phenyl Isocyanide, Thioformanilide.

The thio-amides resemble the amides and are readily broken up into fatty acids,
SHjiNHj and amines. They manifest more of an acid character than the oxy-
gen amides, dissolve in alkalies, and readily yield metallic derivatives by the
replacement of I hydrogen atom of the amidogroup.

In the action of hydroxylamine upon the thio-amides the S-atom is replaced by
the iso-nitroso-group, with production of amidoximes (see these).

When iodides of the hydrocarbons act on the sodium compound of thio-aceta-
nilide, iso-thio-acetanilides containing alcohol radicals result: —

<^«a-<N(Na).C3H, + CH3I = CH,.cQ^^^^ + Nal.
Sodium Thio-acetanilide. Methyl-isothio-acetanilide.

These are viewed as derivatives of the so called isothio-acetamide, CHg.

C^-vTTT The latter compound has not yet been obtained free; it is isomeric

\iMrl. /^PT

with thio-acetamide {Berichte^ 12, 1062, and 16, 144). The forms CHq.C^^ -^ttt

and CHg.C^ ^^ are probably tautomeric. Hydrochloric acid converts tl^e iso-

THIO-AMIDES. 26 1

compounds having alcohol radical groups, into aniline and esters of thio-acetic
acid (p. 250).

The so-called imido-thio-ethers (see these) possess a constitution like the isothio-
amides.

8. CYAN-, SULPHO- AND AMIDO-DERIVATIVES OF THE ACIDS.

In the acids, the hydrogen of the acid radicals can be substituted,
the same as in the hydrocarbons, by the monovalent groups, SO3H,
sulpho-, CN, cyan-, NHj, amido-, etc. The resulting derivatives,
having two side groups, belong to the divalent compounds, and are
in part described with the divalent alcohols and acids, for the prepa-
ration of which they serve as transition stages. Here we will merely
call attention to the ordinary methods used in their production: —

The Sulpho-derivatives of the monobasic acids correspond
perfectly to the sulpho-compounds of the alcohol radicals (p. 152),
and are obtained according to similar methods: —

(1) By the action of sulphur trioxide upon the fatty acids r —

CH3.C0,H + SO3 = CH./^O^g.

Acetic Acid. Sulplio-acetic Acid.

or by acting with fuming sulphuric acid on the nitriles, or amides of the acids, in
which case the latter first change to acids.

(2) By heating concentrated aqueous solutions of the salts of the monosubsti-
tuted fatty acids with alkaline sulphites (p. 151) : — •

CHj.Cl.COjK + K.SO3K = CH /gQ^^ + KCl.

Some of the sulpho-fatty acids are analogously obtained by the addition of alka-
line sulphites to unsaturated acids [BeruAie, 18, 483) : —

CH3.CH:CH.C02H -f K2SO3 = CHj.CH^.Ch/^^s^

(3) By oxidizing the thioacids corresponding to the oxy-acids with nitric
acid : —

„TT /SH 1 -n CVf /^'^s^

•^^^XCO^H + 3" - ^"2\C0,H.
ThioglycoUic Acid.

The formulas indicate these sulpho-acids to be dibasic (mixed
carboxylic and sulpho-acids). They correspond to the dicarboxylic

acids, like CH2('^q''^— malonic acid. They are mostly crys-
talline substances, easily soluble in water and deliquescent in the
air. Their salts generally crystallize well. The sulpho-group in
them is not so intimately combined as in the sulphonic acids of the
alcohol radicals. Boiling alkalies convert them into oxy-acids : —

262 ORGANIC CHEMISTRY.

Sulpho-acetic Acid, CHj/Iq^-OH^ ^^ obtained by oxidizing isothionic

acid, CHj(OH).CH2.S03H, with nitric acid. Sulpliuric acid liberates it from its
readily soluble barium salt. The acid crystallizes with lyi molecules H^O in

deliquescentprisms, which fuse at 75°. The barium salt, CH2<f ^Q^yBa + H^O,

forms leaflets. Pentachloride of phosphorus converts it into the chloride,

CH,/?,9-29}. By reduction of the latter with tin and hydrochloric acid thio-

glycoUic acid, CH^^^q jj is produced.

Its ethyl ester results from the action of ethyl iodide upon its silver salt. The
hydrogen atotns of the CH 2 -group in this ester (as in acetoacetic and malonic
esters) can be replaced by alkyls {Berichte, 21, 1550).

See Berichte, 22, 518, upon the sulpho- derivatives of the higher acids of the
marsh-gas series.

The Cyan-derivatives are obtained by heating the mono-
halogen acids (their salts or esters) with aqueous or alcoholic potas-
sium cyanide : —

CH^Cl.COjK -f CNK = CH /^Q ^ + KCl.

In this reaction the halogen is not only replaced by cyanogen, but very often
there is a simultaneous doubling of the acid ester {Berichte, 21, 3166 and 3399).

As a usual thing they crystallize poorly and are unstable. ' When
boiled with alkalies or acids they are converted into dibasic acids
(p. 211):—

Cyanacetic Acid. Malonic Acid.

Cyanformic Acid, CN.COjH. In the following pages this will be considered
as cyancarbonic acid.

Cyanacetic Acid, CH2(CN).C02H, is derived from monochlor-
acetic acid. It is a crystalline mass, readily soluble in water, melt-
ing at 65° {Berichte, 20, Ref. 477), and splitting up into CO2 and
acetonitrile, CH3.CN, at 165°. Malonic acid is produced when it
is boiled with alkalies or acids.

Preparation. — Boil monochloracetic ester (5 pirts) with potassium cyanide (6
parts) and water (24 parts), or alcohol, until the odor of prussic acid has disap-
peared, then neutralize /the solution with HjSO^, concentrate, supersaturate with
sulphuric acid and withdraw the cyanacetic acid by shaking the liquid with ether.

Ethyl Cyanacetate, CH„f^ „,, „ „ boils about 207°. The hydrogen of its

CHj-group is replaceable by alkyls {^Berichte, 20, Ref. 477) and acid radicals {^Ber-
ichte, 21, Ref. 353). Aceto-cyanacetic ester is identical with cyan-acetoacetic
ester {Berichte, 20, Ref. 477).

CYANOGEN COMPOUNDS. 263

a-Cyanpropionic Acid, CH3.CH(CN).C02H, from a-brompro-
pionic acid, yields isosuccinic acid when saponified. Its ethyl ester
boils at 197°. The hydrogen of its CH-group can be replaced by
sodium and alkyls {Berichte, 21, 3164). /J-Cyanpropionic Acid,
CH2(CN).CH2.COiH, from ;3-chlorpropionic acid, yields ordinary
succinic acid when saponified.

CYANOGEN COMPOUNDS.

The monovalent group CN, in which trivalent nitrogen is linked
with three affinities to carbon, N=C — '-, is capable of forming quite a
number of different derivatives. It shows in many respects great
similarity to the halogens, chlorine, bromine, and iodine. Like
these, it combines with hydrogen, forming an acid, and combines
with the metals to salts which resemble and are frequently isomor-
phous with the haloid salts. Thus, the alkali salts assume the cube
form in crystallizing, and silver cyanide is in all respects like silver
chloride. Potassiurn and sodium burn in cyanogen gas, as in chlo-
rine, forming cyanides. The monovalent group CN cannot exist
free, but it doubles itself, just as all other monovalent grdaps,?.^.,
CH3, when it separates from its compounds, and we get the mole-
cule : —

Dicyanogen, C^N^ = NC— CN.

In organic cyanogen compounds where CN is attached to alkyls
the union of the cyanogen group is very firm. Yet the nitrogen
atom in CN can be easily liberated as ammonia, and the carbon
atom will pass into the carboxyl group, COjH. This behavior
is characteristic of cyanogen derivatives. It may be effected by the
absorption of water, which can occur by boiling with acids and
alkalies: —

R_CN 4- 2H2O = R— CO.OH -t- NH3.

Nascent hydrogen causes a partial separation of nitrogen, pro-
ducing amines : —

CH=N + 2H2 = CHg-NHj. -

An oxygen atom can be inserted into the CH group — see cyanic
acid.

A similar, partial separation accounts also for the condensation
of the cyan-group to polymeric forms, e. g., dicyanogen, CjN,,
and tricyanogen, C3N3. The following formulas express their

structure : —

— C=N — C=N— C—

I I and I II

IJ=C— N=C— N

Dicyanogen, Divalent. |

Tricyanogen, Trivalent,

264 ORGANIC CHEMISTRY.

Very many cyanogen derivatives readily adapt themselves to such
polymerizations.

Besides the above normal cyanogen derivatives there also exist
isomeric Pseudo- and /r^-cyanogen compounds. These will receive
attention further on (with the cyanic acids and carbylamines).

The nitrogen atom in the cyanogen group is trivalent ; it may be
considered as ammonia in which carbon replaces the hydrogen
atoms. This would explain why so many cyanogen derivatives, in
the same manner as the amides, combine directly with the haloid
acids and metallic chlorides, yielding compounds similar to the
ammonium salts : —

CH3.CN.HCI = ch,,.c=n/^j.

These are, however, unstable. Perhaps it is necessary to admit (p.
258) that the halogen hydride has effected an entrance for itself in
the CN group (as in CH3.CCI = N.CH3).

Yellow prussiate of potash and potassium cyanide serve as start-
ing-out substances in the preparation of the cyanogen derivatives.
Potassium cyanide is obtained by the ignition of nitrogenous
organic matter with KOH or potashes (see Text-Book of Inorganic
Chemistry). The direct union of carbon and nitrogen to cyanogen
is only effected with difificulty. It may be accomplished by con-
ducting nitrogen over a mixture of carbon and metallic potassium
or potassium carbonate raised to a red heat. Potassium cyanide is
then formed. The yield is more abundant if ammonia gas be con-
ducted over the mixture. The ignition of carbon in ammonia gas
yields ammonium cyanide : —

C + 2NH3 = CN.NH^ -I- Hj.

All these methods, however, are not applicable on a large scale.

Free Cyanogen or Dicyanogen, CjNj ^= NC.CN, is present
in small quantity in the gases of the blast furnace. It is obtained
by the ignition of silver or mercury cyanide : —

Hg(CN), = C,N, -f Hg.

The transposition proceeds more readily by the addition of mercuric chloride.

It is most readily prepared from potassium cyanide. To this end the concen-
trated aqueous solution of i part KCN is gradually added to 2 parts cupric sul-
phate in 4 parts of water. Heat is then applied. At first a yellow precipitate of
copper cyanide, Cu(CN)2, is produced, but it immediately breaks up into cyanogen
gas and cuprous cyanide, CuCN.

Its preparation from ammonium oxalate, through the agency of
heat, is of theoretical interest : —

CO.O.NH^ CN

1 = I + 4H2O.

CO.O.NH. CN

CYANOGEN COMPOUNDS. 265

It is on this account to be considered as the nitrile of oxalic
acid.

Cyanogen is a colorless, peculiar-smelling, poisonous gas, of
specific gravity 26 (H = i). It may be condensed to a mobile
liquid by cold of — 25'', or by a pressure of four atmospheres at
ordinary temperatures. In this condition it has a sp. gr. 0.866,
solidifies at — 34° to a crystalline mass, and boils at — 21°. It
burns with a bluish-purple mantled flame. Water dissolves 4 vol-
umes and alcohol 23 volumes of the gas.

On standing the solutions become dark and break up into ammonium oxalate
and formate, hydrogen cyanide and urea, and at the same time a brown body, the
so-called azulmic acid, C4H5N5O, separates. With aqueous potash cyanogen
yields potassium cyanide and isocyanate. In these reactions the molecule breaks
down, and if a slight quantity of aldehyde be present in the aqueous solution only
oxaraide results : —

CN CO.NH2

I + 2H,0 = I

CN CO.NHj.

CN
With hydrogen sulphide cyanogen yields hydroflavic acid, C2N2.H2S= |

CS.NHj CS.NH2,

and hydrorubianic acid, C2N2.2H2S = | These two compounds may

CS.NHj.
be considered thioamides, or as tautomeric isothioamides (p. 260) : —

CN CN CS.NH2 C(NH).SH

I or I I or I

CS.NH2 C(NH).SH CS.NH2 C(NH).SH

Hydroflavic Acid. Hydrorubianic Acid.

The first consists of yellow crystals, the second of red, and is best prepared by
conducting cyanogen gas into an alcoholic solution of potassium sulpTiydrate, and
adding hydrochloric acid {Berichte, 22, 2305). It unites with two molecules of
hydroxylamine (like the thioamides) to form oxaldiamidoximes.

On heating mercuric cyanide there remains a dark substance, paracyanogen, a
polymeric modification, (C2N2)n. Strong ignition converts it again into cyan-
ogen. It yields potassium cyanate with caustic potash.

Hydrocyanic Acid, CNH, Prussic Acid, is obtained from
various plants containing amygdalin (from cherry-stones, bitter
almonds, etc.), on standing in contact with water, when the
amygdalin undergoes a fermentation, breaking up into hydro-
cyanic acid, sugar and oil of bitter almonds. Its production
from ammonium formate by the application of heat is of theoretic

interest : —

CHO.O.NH^ = CHN -f 2H2O.

This reaction would show it to be the nitrile of formic acid.

Hydrogen cyanide may also be obtained by passing the silent
electric discharge through a mixture of CjN^ and hydrogen :
C2N2 -I- H2 = 2CNH.

266 ORGANIC CHEMISTRY.

The metallic cyanides yield it when they are distilled with
mineral acids.

Anhydrous hydrocyanic acid is a mobile liquid, of specific grav-
ity 0.697 at 18°, and becomes a crystalline solid at — 15°. It boils
at -f- 26.5°. Its odor is peculiar and resembles that of oil of bitter
almonds. The acid is extremely poisonous.

The following procedure serves for the preparation of aqueous prussic acid.
Finely pulverized yellow prussiate of potash (10 parts) is covered with a cooled
mixture of sulphuric acid (7 parts) and water (10 to 40 parts, according to the
desired strength of the prussic acid), and then distilled from a retort provided
with a condenser. The heat of a sand-bath is necessary. The decomposition of
the yellow prussiate occurs according to the equation : —

2FeCyeK^ + aSO^H, = Fe^Cy^K, + 3SO4K, + 6CNH.

About half the cyanogen contained in the ferrocyanide is converted into hydro-
cyanic acid.

The anhydrous acid can be obtained from the hydrous by fractional distillation
and dehydration by calcium chloride.

The aqueous acid decomposes readily upon standing, yielding
ammonium formate and brown substances. The presence of a
very slight quantity of stronger acid renders it more stable. When
warmed with alkalies or mineral acids it breaks up into formic acid
and ammonia : —

CNH + all^O = CHO.OH + NH,.

Nascent hydrogen (zinc and hydrochloric acid) reduces it to
methylamine (p. 159).

Hydrocyanic acid is a feeble acid, and imparts a faint red color
to blue litmus. Like the haloid acids, it reacts with metallic oxides,
producing metallic cyanides. From solutions of silver nitrate it
precipitates silver cyanide, a white, curdy precipitate.*

* In hydrocyanic acid the hydrogen, replaceable by metals, is in union with
carbon, whereas, ordinarily, it is only the hydrogen of hydroxyl (in acids and
alcohols) that is capable of replacements like this. The acetylenes, — C^CH,
nitroparaffins (p. 107), aceto-acetic esters and the analogously constituted malonic
esters manifest a similar deportment. In these compounds, two or three carbon
valences are generally saturated by negative elements or groups, and they
manifest also analogous behavior, in that their alkali salts are less stable than those
with the heavy metals.

The hydrogen attached to nitrogen possesses also the function of acid hydro-
gen, if two aCSnities of the nitrogen are combined with negative groups, as in
the imides : —

CO:NHand~^^\NH.

HALOGEN COMPOUNDS OF CYANOGEN. 267

To detect small quantities of free prussic acid or its soluble salts, saturate the
solution under examination with caustic potash, add a solution of a ferrous salt
contammg some ferric salt, and boil for a short time. Add hydrochloric acid to
dissolve the precipitated iron oxides. If any insoluble Prussian blue should re-
main, It would indicate the presence of hydrocyanic acid. The following reaction
IS more sensitive. A few drops of yellow ammonium sulphide are added to the
prussic acid solution, and this then evaporated to dryness. Ammonium sulpho-
cyanide will remain, and if added to a ferric salt, will color it a deep red.

Dry prussic acid combines directly with the gaseous halogen
hydrides (p. 264) to form crystalline compounds like CHN.HCl,
easily soluble in water and ether. The aqueous solutions rapidly
decompose, yielding formic acid and ammonium salts. The acid
also unites with some metallic chlorides, e. g., FejCle, SbCIj.

HALOGEN COMPOUNDS OF CYANOGEN.

These result by the action of the halogens upon metallic cyanides.
The chlorid? and bromide can condense to tricyanides, in which
we assume the presence of the tricyanogen group, C3N3 (p. 263).

Cyanogen Chloride, CNCl, is produced by acting with chlo-
rine upon aqueous hydrocyanic acid. It is a mobile liquid, solidi-
fying at —5°, and boiling at + 15.5°. It is heavier than water,
and only slightly soluble in it, but readily dissolved by alcohol and
ether. Its vapors have a penetrating odor, provoking tears, and
acting as a powerful poison.

In preparing it, saturate a cold mercuric cyanide solution with chlorine. The
cyanogen chloride which escapes on the application of heat, is conducted through a
tube filled with copper turnings, to free it of chlorine. Or strongly cooled prussic
acid (containing 20 per cent. CNH), is saturated with chlorine gas, the oily cyano-
gen chloride separated, and then distilled over mercuric oxide, to remove excess of
prussic acid.

Cyanogen chloride combines with different metallic chlorides.
With ammonia, it yields ammonium chloride and cyanamide,
CN.NHj. Alkalies decompose it into metallic cyanides and iso-
cyanates.

Tricyanogen Chloride, C3N3CI3, solid chlorcyan, is produced when the liquid
chlorine is kept in sealed tubes. It is formed directly by leading chlorine into an
ethereal solution of CNH, or into anhydrous hydrocyanic acid exposed to direct
sunlight {Berichte, ig, 2056). It appears, too, in the distillation of cyanuric acid,
C3O3N3H3, with phosphorus pentachloride. It crystallizes in shining needles or
leaflets, melts at 146°, and boils at 190°. It is not very soluble in cold water, but
readily in alcohol and ether. Its vapor density equals 92 (H = i). When boiled
with acids or alkalies, it breaks up into hydrochloric and cyanuric acids (Berichte,
19, Ref. 599) :—

C3N3CI3 + 3H,0 = C3N3(OH)3 + 3HCI.

268 , , ' ORGANIC CHEMISTRY.

Cyanogen Bfotnide, CNBr, is obtained when bromine acts on anhydrous
prussic acid or upon Ynercuric cyanide : —

Hg(CN)2 + zBrj = HgBrj + 2CNBr.

It is a very volatile, crystalline substance, readily soluble in water, alcohol and
ether. On heating the anhydrous bromide or its ethereal solution in sealed tubes
to 130-140°, it becomes polymeric tricyanogen bromide, CjNjBrg. The latter
is more easily obtained By heating dry yellow or red prussiate of potash with bro-
mine at 250° [Berichte, 16, 2893), or on conducting HBr into the ethereal solution
of CNBr {Berichte, 18, 3262). It is an amorphous white powder, soluble in ether
and benzene. It melts about 300°, and is volatile at higher temperatures. It
decomposes in moist air, or upon boiling with water, into HBr and cyanuric acid.

Cyanogen Iodide, CNI, is prepared by subliming a mixture of mercuric cya-
nide (I molecule) and iodine (2 molecules) ; or by adding iodine to a concen-
trated aqueous solution of potassium cyanide. The cyanogen iodide which results
is withdrawn by ether. It has a sharp odor, dissolves in water, alcohol and ether,
and subUmes near 45°, without melting, in brilliant white needles. Ammonia
converts it into cyanamide and ammonium iodide.

Cyanuric Iodide, C3N3I3, is produced by the action of hydriodic acid upon
cyanuric chloride. It is a dark brown, insoluble powder. At 125° water decom-
poses it into hydrogen iodide and cyanuric acid. At 200° it readily breaks up into
iodine and paracyanogen, (CN)o {Berichte, ig, Ref. 599). *

METALLIC DERIVATIVES OF CYANOGEN.

The metallic derivatives of cyanogen have already been considered
in inorganic chemistry. Here attention will only be directed to
certain generalizations.

The properties of and the methods of preparing the metallic cyan-
ides vary greatly. The alkali cyanides may be formed by the direct
action of these metals upon cyanogen gas ; thus, potassium burns
with a red flame in cyanogen, at the same time yielding potassium
cyanide, CjNj -f Kj =: 2CNK. The strongly basic metals dissolve
in hydrocyanic acid, separating hydrogen and forming cyanides.
A more common procedure is to act with the acid upon metallic
oxides and hydroxides : 2CNH + HgO = Hg(CN)2 + HjO. The
insoluble cyanides of the heavy metals are obtained by the double
decomposition of the metallic salts with potassium cyanide.

The cyanides of the light metals, especially the alkali and alkaline
earths, are easily soluble in water, react alkaline and are decomposed
by acids, even carbon dioxide, with elimination of hydrogen cya-
nide ; yet they are very stable, even at a red heat, and sustain no
change. The cyanides of the heavy metals, however, are mostly
insoluble, and are only decomposed, or not at all, by the strong
acids. When ignited the cyanides of the noble metals suffer de-
composition, breaking up into cyanogen gas and metals.

The following simple cyanides may be mentioned : —

Potassium Cyanide, KCN, crystallizes in cubes or octahedra, and fuses at a

METALLIC DERIVATIVES OF CYANOGEN. 269

bright red heat to a clear liquid. In moist air it deliquesces and gives up (by the
action of carbon dioxide) hydrogen cyanide. It is scarcely soluble in absolute
alcohol, but dissolves readily in aqueous alcohol. The best mode of preparing
chemically pure potassium cyanide consists in conducting prussic acid into an
alcoholic solution of KOH (in 90 per cent, alcohol). Take i part KOH for 3
parts of the yellow prussiate (p. 266). The potassium cyanide separates as a
powder or jelly, which is drained upon a filter. The so-called Liebig potassium
cyanide, occurring in trade, contains potassium cyanide and isocyanate. It is
made by igniting a mixture of dry yellow prussiate of potash (8 parts) with pure
potashes (3^ parts) : —

FeCyjK^ + COgKj = sKCy + CNOK + CO^ + Fe.

At present chemically pure potassium cyanide is obtained by mere ignition of
potassium ferrocyanide : —

Fe(CN)„K, = 4KCN + FeC, + N,.

The exceedingly finely divided iron carbide which adheres to the salt is re-
moved by filtering the molten mass through porous clay crucibles.

The aqueous or alcoholic solution becomes brown on exposure, and when boiled,
rapidly decomposes into potassium formate and ammonia. If fused in the air or
with metallic oxides which are readily reduced, potassium cyanide absorbs oxygen,
and is converted into potassium isocyanate. When fused with sulphur it yields
potassium thiocyanate.

Ammonium Cyanide, NH^CN, is formed by the direct union of CNH with
ammonia, by heating carbon in ammonia gas, and by conducting carbon monoxide
and ammonia through red-hot tubes. It is best prepared by subliming a mixture
of potassium cyanide or dry ferrocyanide with ammonium chloride. An aqueous
solution of it may be made by distilling the solution of ferrocyanide and ammonium
chloride. It yields colorless cubes, easily soluble in alcohol and subliming at 40°,
with partial decomposition into NHg and CNH. When preserved it becomes
dark in color and decomposes.

Mercuric Cyanide, Hg(CN)2, is obtained by dissoli^^ merpuric oxide in
hydrocyanic acid, or by boiling Prussian blue (8 parts) mm mercuric oxide (l
part) with water, until the blue coloration disappears. It dissolves readily in hot
water (in 8 parts cold water), and crystallizes in bright, shining, quadratic prisms.
When heated it yields cyanogen and mercury (p. 264).

Silver Cyanide, AgCN, is precipitated as a white, curdy compound from silver
solutions by potassium cyanide or prussic acid. It resembles silver chloride very
much. It darkens on exposure to the air, and dissolves readily in ammonium
hydrate and potassium cyanide.

From some reactions, it would seem that silver cyanide may contain the iso-
cyanogen group, C = N — , and that silver, consequently, is linked to nitrogen
(as in silver nitrite, NOjAg, p. 106). Compare Carbylamines (p. 287).

Compound Metallic Cyanides. The cyanides of the heavy metals
insohible in water dissolve in aqueous potassium cyanide, forming
crystallizable double cyanides, which are soluble in water. Most
of these compounds behave like double salts. Acids decompose
them in the cold, with disengagement of hydrocyanic acid and
the precipitation of the insoluble cyanides : —

AgCN.KCN + HCl == AgCN + KCl -\- CNH.

270 ORGANIC CHEMISTRY.

In Others, however, the metal is in more intimate union with the
cyanogen group, and the metals in these cannot be detected by the
usual reagents. Iron, cobalt, platinum, also chromium and man-
ganese in their ic state, form cyanogen derivatives of this class.
The stronger acids do not eliminate prussic acid from them, even
in the cold, but hydrogen acids are set free, and these are capable
of producing salts : —

Pe(CN),K^ + 4HCI = Fe(CN)eH^ + 4KCI.
Potassium Ferrocyanide. Hydroferrocyanic Acid.

It may be assumed that polymeric cyanogen groups — dicyanogen
-and tricyanogen (p. 263) — are present in these derivatives of
cyanogen : —

. "/C3N3.K2 in^CjNj.K /C2N2.K

Fe<.C3N3.K' Fe\c». P'\C,N,.K.

Potassium Ferrocyanide. Potassium Ferricyanide. Potassium Platinocyanide.

This view is sustained by the. fact that' these cyanides, although
soluble in water, are yet not poisonous. We do not know of a
sharp line'of j^ifference between cyanides of the first and those of
the second variety ; different compounds, e. g., potassium gold cy-

III
anide, Au(CN)4K, show an intermediate behavior. The most import-
ant compound cyanides have been already treated in the Inorganic
Chemistry.

Nttroprussides^^hest arise on treating the ferrocyanides with
nitric acid. ••.T^^ftost important of them is

Sodium^Nitroprusside. Its constitution has not yet been
definitely determined {Berichte, 15, 2613). The simplest expres-
sion of it is given by the formula, Fe(CN)5(NO)Na2 + zH^O. It
crystallizes in beautiful red rhombic prisms, readily soluble in water.
Sunlight decomposes it into nitric oxide and Prussian blue.

Preparation. — Heal pulverized potassium ferrocyanide with two parts concen-
trated nitric acid, diluted with an equal volume of water, until ferric chloride
ceases to produce a blue precipitate. The cooled solution is filtered off from the
separated saltpetre, saturated with soda, and evaporated until near the point of
crystallization, when 3-4 parts of alcohol are added.

Sodium nitroprusside serves as a very delicate reagent for alka-
line sulphides, which give with it an intense violet coloration even
in very dilute solution.

It yields precipitates with most of the heavy metals. When hydrochloric acid
is added to the nitroprussides, hydrogen nitroprusside, Fe(CN)5(NO)H2 + H^O,
is liberated. This crystallizes in vacuo from its aqueous solution, in dark-red
prisms.

OXYGEN COMPOUNDS OF CYANOGEN. 271

OXYGEN COMPOUNDS OF CYANOGEN.

The empirical formula, CNOH, of cyanic acid, has two possible
structures: — . i

N=CO— H and CO=N— H.
Normal Cyanic Acid. Isocyanic Acid. -

These formulas are probably tautomeric, so that ihey can both be assigned to the
known cyanic acid. The difference between them is fcst observed when hydrogen
is replaced by radicals. The ordinary salts of cyani© acid appear to be derivatives
of the isocyanic acid, CO:NH (or carbimide, the imide of carbonic acid), as iso-
cyanic esters are produced by the action of alkyl iodides upon the silver salt. The
ordinary cyanic esters are constituted according to the formula, CO:NR, and are
termed isocyanic esters, while the esters of normal cyanic acid, CN.OR, are desig-
nated cyanetholines (p. 273).

Ordinary Cyanic Acid, CONH, is obtained by heating poly-
meric cyanuric acid. The vapors which distil over are condensed
in a strongly cooled receiver.

The acid is only stable below o°, and is aj mcfbile, very volatile
liquid, which reacts strongly acid, and smells ver35|jna|ich like glacial
acetic acid. It produces blisters upon the skin. About o°, the
aqueous solution is rapidly converted into carbon dioxide and
ammonia: —

CONH -f H^O = CO2 + NH3.

At 0°, the aqueous cyanic acid passes rapidly into the polymeric
cyamelide — a white, porcelain-like mass, which is insoluble in water,
and when distilled reverts to cyanic acid. jA1^^o°, the conver-
sion of liquid cyanic acid into cyamdide.oqHPB|ft|mpanied by
explosive foaming. Cyanic acid dissolv-es ™iij^WwB7*7^di°g-
esters of allophanic acid.

The salts of the above acid are obtained by double decomposition from the
potassium salt; those of the heavy metals are insoluble in water, and those of the
earths are precipitated by alcolyil. Heat decomposes both varieties into CO2 and
salts of cyanamide (see this).

Potassium Isocyanate, QO:^'^,ordinarycyanate of potassium,
is formed in the oxidation of potassium cyanide in the air or with
readily reducible metallic oxides (CNK -f O = CO:NK). It
results, too, on conducting dicyanogen, or cyanogen chloride into
caustic potash {Berichte, 13, 2201). The salt crystallizes in shining
leaflets, resembling potassium chlorate, and dissolves readily in cold
water, but with more difficulty in hot alcohol. In aqueous solution
it decomposes rapidly into ammonia and potassium carbonate.

Preparation.— F\3S& in a crucible a mixture of dehydrated yellow prussiate of
potash (8 parts), potashes (3 parts), and gradually add, while stirring, lead oxide

272 ORGANIC CHEMISTRY.

or minium (15 parts) : CNK + PbO = CNOK + Pb. The reduced lead melts
together on the bottom of the vessel. The white mass is poured out and the
potassium cyanate extracted with alcohol. .

Potassium isocyanate ppcipitates aqueous solutions of the heavy
metals. The lead, silver and mercurous salts are white, the cupric
salt is green in color.

Ammonium cyanate, CN.O.NH^ or C0:N(NH4), is a white crystalline powder,
formed by contact of cyanic acid vapors with dry ammonia. Caustic potash decom-
poses it into potassium isocyanate and ammonia. On evaporating the aqueous
solution it passes into isomeric urea : —

CON.NH^ = Co/^g^.

The cyanates of the primary and secondary amines are similarly converted into
alkylic ureas, whereas the salts of the tertiary amines remain unchanged.

Three molecules of CNOH condense to Trtcyanic or Cyanurtc
Acid, C3N3O3H3 (p. 263). Here again two structural cases are pos-
sible : —

HO— C=N— C— OH OC— NH— CO

I II and I I

N=C— N HN— CO— NH

i

Isocyanuric Acid

locyar

r Tricarbimide.

H

.Tiuric Acid.

Oratnary^PmMR^cid is most probably constituted according to
formula (i), because when sodium alcoholates act upon cyanuric
bromide, CgNaBrj, and alkyl iodides upon ordinary silver cyanate
esters of normal cyanuric acid result (p. 275). Isocyanuric acid
(formula 2) is not known in a free state, and is probably tautomeric
with' normal cyanuric acid, since upon saponifying the isocyanuric
esters (p. 276), constituted according to the carbimide formula
(2), ordinary cyanuric acid invariably results {Rerichte, 20, 1056).

Ordinary Cyanuric Acid, C3O3N3H3, probably normal cyan-
uric acid, C3N3(OH)3 (see above), is obtained from tricyanogen
chloridef C3N3CI3, by boiling the latter with water and alkalies (see
above).

Dilute acetic acid added to a solution of potassium isocyanate,
gradually separates primary potassium isocyanate, C3N3O3H2K, from
which mineral acids release cyanuric acid. It appears, too, on
heating urea : —

3C0N,H, = C,03N3H3 + 3NH3.

ESTERS OF CYANIC ACID. 273-

Preparation. — Carefully teat urea until the diseng^ement of ammonia ceases
and the mass, which at first fused, has become solid again. The residue is dis-
solved in potash and the cyanuric acid precipitated with hydrochloric acid. A
better plan is to lead dry chlorine gas over fused urea at a temperature of 130-
140° :—

aCONjH^ + 3CI = C3O3N3H3 + 2NH4CI + HCl + N.

Cold water is employed to remove the ammonium chloride from the residue, and
the latter recrystallized from hot water.

Cyanuric acid is more easily obtained by heating tribromcyanide with water
{Berickte, 16, 2893).

Cyanuric acid crystallizes from aqueous solution wjth 2 molecules
of water (C3N3O3H3 -(- 2H2O) in large rhombic prisms. It is
soluble in 40 parts cold water, and easily soluble in hot water and
alcohol. When boiled with acids it decomposes into carbonic acid
and ammonia. When distilled it breaks up into cyanic acid. PCI5
converts it into tricyanogen chloride.

Cyanuric acid is tribasic and yields three series of salts, all of
which crystallize well. The salts of the heavy metals are not soluble
in water. A characteristic salt is the trisodium salt, C3N803Na3.
This separates from aqueous solutions of cyanuric acid upon warm-
ing them with concentrated sodium hydroxide. It forms minute
needles.

Two supposed isomeric cyanuric acids are identical with ordinary
cyanuric acid {Berkhte, 19, 2022).

I. ESTERS OF THE CYANIC ACIDS.

Those of normal cyanic acid, CN.OH (p. 271), result when cyan-
ogen chloride acts upon sodium alcoholates : —

CNCl + C2H5 ONa = CN.O.C2H5 + NaCl.

They are also termed cyanetholines. They are liquids, of ethereal
odor, are insoluble in water, and suffer decomposition when distilled.
The ethyl ester is the only one that has been closely studied.

Ethyl Cyanic Ester, CN.O.C^H-, cyanetholine, is obtained by the action of
cyanogen chloride or iodide upon a solution of sodium ethylate in absolute alcohol.
On diluting with water it precipitates out in the form of a colorless oil, of sp. gr.
1. 127 at 15°- It dissolves readily in alcohol ,and ether. When boiled with caustic
potash it decomposes into CO^, NH, and ethyl alcohol. Acid esters of isocyanuric
acid are produced when it is boiled with hydrochloric acid. It polymerizes into
solid ethyl cyanuric esters after standing some time.

The homologous esters are prepared in a similar manner, but they have been but
little investigated.
23

2 74 ORGANIC CHEMISTRY.

Esters of Isocyanic Acid, CO:NH, ordinary cyanic acid esters.
Wilrtz prepared these, in 1848, by distilling potassium ethyl sulphate
with potassium isocyanate : —

SOjKCCjHs) + CO:NK = CO;N.C2H5 + SO^Kj.

Esters of isocyanuric acid are formed at the same time, in conse-
quence of polymerization. Isocyanic esters are produced, too, by
oxidizing the carbylamines with mercuric oxide : —

C^H^.NC + O = C^H^.NrCO;
and by the action of silver isocyanate upon alkyl iodides : —

C2H5I + CO:NAg = COrN.C^Hs + Agl.

These esters are volatile liquids, boiling without decomposition,
and possessing a very disagreeable, penetrating odor, which provokes
tears. They are decomposed by water and alcohol, but dissolve
without decomposition in ether. On standing they pass rather
rapidly into the polymeric isocyanuric esters.

In all their reactions they behave like carbimide derivatives.
Heated with KOH they become primary amines and potassium
carbonate (p. 159) : —

COiN.CjHj + 2KOH = CO3K2 + NH2.C2H5.

A.cids in aqueous solution behave similarly : —

CO:N.C2H5 + HjO + HCl = CO2 + C^Hs.NH^.HCl.

With the amines and ammonia they yield alkylic ureas (see these).
Water breaks tMj^ up at once into CO2 and dialkylic ureas. In
this decomposition amines form first, CO2 being set free, and these
combine with the excess of isocyanic ester to dialkylic ureas (see
these).

The esters of isocyanic acid unite with alcohol, yielding esters of carbaininic
acid : —

COrN.C^Hj +C2H,.OH = Co/^^'^^^'"'

They react similarly with the polyvalent alcohols, forming complex carbaminic acid
esters {BericAte, 18, 968).

As derivatives of ammonia the isocyanic esters are capable of combining di-
rectly with the haloid acids : —

^N + HCl = ^^N.HCl.
C,H,/ ^ C,H,/

Water decomposes these products at once into COj and amine salts. They very

probably are identical with the alkyl urea chlorides, C0(^ c\ ^ ^ (^^^ these),

from which the isocyanic esters are again separated by distillation with lime.

ESTERS OF THE CYANURIC ACIDS.

275

Methyl Isocyanic Ester, C0:N.CH3, methyl carbimide, is obtained by dis-
tilling potassium methyl sulphate with potassium isocyanate. It is a very volatile
liquid, boiling at 44°. When boiled with KOH it forms methylamine, CH3.NH,

Ethyl Isocyanic Ester, COrN.CjHj, ethyl carbimide. This boils at 60°, and
has the specific gravity of 0.891. It produces ethylamine with boiling alkalies-
with sodium ethylate it yields triethylamine : — '

CO.-N.CjHj + aCjHj.ONa = COjNa, + N(C2H5)3.

Isoamyl Isocyanic Ester, C0:N.C5Hn, amyl carbimide, from amyl alcohol
of fermentation, boils near 100°.

Allyl Isocyanic Ester, COiN.CjHj, is obtained by heating allyl iodide and
potassium cyanate. It boils at 82°-

2. ESTERS OF THE CYANURIC ACIDS.

The esters of the normal cyanuric acid, C3N3(OH)3 (p. 272), are
formed, as already observed, by the polymerization of the cyanic
esters (cyanetholines) after long standing : —

SCN.O.qH^ = C3N3(0.qH5)„

and are produced directly, together with the cyanic esters, in the
preparation of the latter, by conducting cyanogen chloride into
sodium alcoholates.

A simpler procedure is to act upon the sodium alcoholates with
cyanuric chloride or bromide {Berichte, 18, 3263 and 19,2063): —

C3N3CI3 + 3Na.O.C,H, = C3N3(O.C,H,)3 + sNaCl.

The normal cyanuric esters are also formed by the action of alkyl iodides upon
silver cyanurate, C3N3(OAg)3 at ioo°- Since, however, the normal esters, under
the influence of heat, are transposed into the isomeric isocyanuric esters (see below),
the latter are produced in large quantities even at low temperatures, while at ele-
vated temperatures they are the only products {Berichte, 18, 3269). The separation
of the isomeric esters may be effected by the aid of mercuric chloride, since only
the normal cyanuric derivatives yield with the latter double compounds, which are
characteristic (see, on contrary, Hofmann, Berichte, 19, 2093).

The normal cyanuric esters, on digesting with the alkalies, break up into cyanuric
acid and alcohol. They combine with six atoms of bromine. PCI 5 converts them
into cyanuric chloride.

Methyl Cyanuric Ester, C3Ng(O.CH3)3, crystallizes from hot water or alco-
hol in needles, melting at 135° It boils, with scarcely any alteration, at i6o°-
1 70°. The distillate contains but traces of the iso-ether. If it be boiled for some time
in connection with a return cooler, the conversion into isomeric isocyanuric ester is
complete. It dissolves in concentrated HCl, and is reprecipitated unchanged by
ammonia. Methyl chloride and cyanuric acid are produced on boiling with Ibydro-
chloric acid.

Ethyl Cyanuric Ester, C3N3(O.C2H5)3, is produced when sodium alcoholate
acts upon cyanogen bromide, or cyanuric chloride (see above) ; also from methyl
cyanuric ester, and normal methyl thio-cyanuric ester, when boiled with sodium

276 ORGANIC CHEMISTRY.

ethylate and alcohol. It crystallizes in needles, melts at 29°, and boils unaltered
at 275°. Prolonged boiling, in connection with a return cooler, gradually leads to
the isocyanuric ester (melting at 95°).

Partial saponification of the normal cyanuric esters by NaOH or Ba(0H)2 gives
rise to normal dialkyl cyanuric acids ; these, when heated, rearrange themselves
into dialkyl isocyanuric acids [Berichte, 19, 2067).

Dimethyl Cyanuric Acid, C3N3(O.CH3)j.OH, crystallizes in small leaflets,
melting at l6o°-l8o°, and suddenly passes into dimethyl isocyanuric acid (melting
at 222°). This change is accompanied by the evolution of much heat.

Diethyl Cyanuric Acid, C3N3(O.C2H5'l20H, also melts at i6o°-i8o°, and
is suddenly converted into diethyl isocyanuric acid (m. p. 173°) {Berickie, 18,
3268V

When acid chlorides act upon silver cyanurate mixed anhydrides are formed,
and these are again resolved into their components upon heating with water (Be-
richte, 18, 3261 and 19, 311).

Cyanuric Triacetate, C3N3(O.CjH30)3, melts with partial decomposition at
170°.

Esters of Isocyanuric Acid, C303(N. CH3)3, Tricarbimide
esters, are formed together with the isocyanic esters, when the latter
are prepared by the distillation of KCNO with potassium ethyl
or methyl sulphate. We have already spoken of their formation
as a result of the molecular transposition of the cyanuric esters.
They are solid crystalline bodies, soluble in water, alcohol, and
ether, and may be distilled without decomposition. They pass
into primary amines and potassium carbonate when boiled with alka-
lies, similar to the isocyanates: —

C303(N.C2H,)3 + 6KOH = 3CO3K2 + 3NH2.qH5.

Methyl Isocyanuric Ester, C303(N.CHg)j, crystallizes in bright prisms. It
melts at 175°, and boils undecomposed at 296°. Heated with PCI 5, chlormethyl iso-
cyanuric ester, C303(N.CH2C1)3, is produced, whereas cyanuric chloride results
from normal methyl cyanuric ester (Berichte, 19, 2087).

Ethyl Isocyanuric Ester, C303(N.C2H5)3, consists of large rhombic prisms,
melting at 95° and boiling at 276°. It volatilizes with steam.

Dialkyl Isocyanuric Esters, or Isocyanuric Dialkyl Esters, as C3O3
(N.CHjjjNH, are formed, together with the trialkyl esters and in the distillation
of monoalkyl ureas. They are also obtained from the normal dialkyl cyanuric
acids by a rearrangement in consequence of the action of heat {Berichte, 19, 2069,
2077). They volatilize without decomposition, and, when boiled with alkalies,
break up into carbonate, primary amine and ammonia. See Berichte, 19, 2094,
upon the structure of the dialkyl isocyanuric acids.

Dimethyl-isocyanuric Acid, C303(N.CH3)j.NH, crystallizes from water in
needles, or leaflets, melting at 222°. Its silver salt crystallizes with ]4 molecule
of water, C30s(NCH3)j.NAg + i^Hp.

■ Diethyl-cyanuric Acid, C303(N.C2H5)2.NH, crystallizes in hexagonal prisms,
melting at 173°, and distilling without decomposition.

SULPHUR COMPOUNDS OF CYANOGEN. 277

SULPHUR COMPOUNDS OF CYANOGEN.
The thiocyanic acids are : —

N=C— SH and S=C=NH.
Thiocyanic Acid. Isothiocyanic Acid.

Sulphocyanic Acid. Thiocarbiraide.

These correspond to the two isomeric cyanic acids (p. 271).

The known thiocyanic acid and its salts (having the group
NC.S — ) are constituted according to the first formula. They are
obtained from the cyanides by the addition of sulphur, just as the
isocyanates result by the absorption of oxygen. The different union
of sulphur and oxygen in this instance is noteworthy : —

CNK + 0 = CO:NK. CNK + S = CN.SK.

Isothiocarbimide, CS:NH, and its salts are not known. Its esters
(the mustard oils) do, however, exist and are isomeric with those of
sulphocyanic acid.

Thiocyanic Acid, CN.SH, sulphocyanic acid, is obtained by
distiUing its potassium salt with dilute sulphilric acid, or decom-
posing the rjiercury salt with dry HjS or HCl. It is a liquid, with
a penetrating odor, and solidifies at — 12.5°- It is soluble in water
and alcohol. Its solutions react acid. The free acid, and also its
salts, color solutions of ferric salts a dark red. The free acid
decomposes readily, especially in the presence of strong acids, into
hydrogen cyanide and perthiocyanic acid, C2N2S3H2.

The alkali thiocyanates, like the isocyanates, are obtained by
fusing the cyanides with sulphur.

Potassium Thiocyanate, CN. SK, sulphocyanate of potash, crystal-
lizes from alcohol in long, colorless prisms, which deliquesce in the
air.

Preparation. — Fuse 32 parts sulphur with 17 parts dry potassium carbonate,
add 46 parts dehydrated yellow prussiate of potash, and again heat until the latter
is completely decomposed. The fusion is finally exhausted with alcohol.

The sodium salt is very deliquescent, and occurs in the saliva and urine of dif-
ferent animals.

Ammonium Thiocyanate, CN.S.NH^, is formed on heating prussic
acid with yellow ammonium sulphide, or a solution of ammonium
cyanide with sulphur. It is most readily obtained by heating CS2
with alcoholic ammonia : —

CS2 -H 4NH3 = CN.S.NH^ 4- (NHJ^S.

A mixture of 300 parts concentrated ammonia solution, 300 parts strong alcohol,
and 70-80 parts carbon disulphide, is permitted to stand for a day. Two-thirds
of the liqujd are then distilled off (the distillate, consisting of alcohol and some

278 ORGANIC CHEMISTRY.

ammonium thiocyanate, may be used in a second preparation), and the residue
carefully evaporated until crystallization sets in.

The salt crystallizes in large, clear prisms, which readily dissolve
in water and alcohol. It melts at 147°, and at 170° molecular
transposition into thiourea occurs (similar to ammonium cyanate
(p. 272):—

CN.S.NH^ yields CS^^^^.

The salts of the heavy metals are mostly insoluble, and are obtained by precipi-
tation. The mercury salt, (CN.S)2Hg, is a gray, amorphous precipitate, which
burns on ignition and swells up strongly (Pharaoh's serpents). Tkt ferric salt,
(CN,S)5Fe2, is a black, deliquescent mass, dissolving in water with a deep red
color.

Cyanogen Sulphide, (CN)2S, is formed when cyanogen iodide in ethereal
solution, acts on silver thiocyanate : —

CN.S.Ag + CNI = Agl + (CN)2S.

The product is extracted with carbon disulphide, and the solution evaporated.
Cyanogen sulphide forms rhombic plates, melting at 65° and subliming at 30°.
Its odor resembles that of the iodide, and the compound dissolves in water, alco-
hol and ether. KOH breaks it up into potassium thiocyanate and isocyanate : —

(CN)2S + 2KOH = CN.SK + CO.NK + H^O.

Pseudo-Cyanogen Sulphide, CjNjHSj, is formed in the oxidation of potas-
sium sulphocyanide with nitric acid or chlorine. It is a yellow, amorphous powder
insoluble in water, alcohol and ether. It dissolves with a yellow color in alkalies.

Kanarine is similar to and probably identical with pseudo- cyanogen sulphide.
It is obtained from KCNS by electrolysis, or by oxidation with KCIO3 and HCl
(Berichte, 17, Ref. 279, and 18, Ref. 676). It is applied as a yellow or orange dye
for wool and does not require a mordant.

ESTERS OF THE THIOCYANIC ACIDS.

Those of normal thiocyanic acid, CN.SH, are obtained by distil-
ling organic salts of sulphuric acid in concentrated aqueous solution
with potassium sulphocyanide, or by heating with alkyl iodides : —

CN.SK + C2H5I = CN.S.C2H5 +KI.

Further, by the action of CNCl upon salts of the mercaptans: —

C2H5.SK 4- CNCl = C2H5.S.CN -f KCl.

They are liquids, not soluble in water, and possess a leek-like odor.
Nascent hydrogen (zinc and sulphuric acid) converts them into
hydrocyanic acid and mercaptans : —

CN.S.C^Hj -f- Hj = CNH -j-CjHj.SH.

ESTERS OF THE THIOCYANIC ACIDS. 279

With aqueous potash they behave as follows : —

2CN.S.C2H5 + 2KOH = (CjHJ^S^ + CNK + CONK -f H^O.

On digesting with alcoholic potash the reaction is : —

CN.S.C2H5 + KOH = CN.SK + C2H5.OH.

The isomeric mustard oils do not afford any potassium sulpho-
cyanate. With HjS they yield the dithiourethanes, whereas the
isomeric mustard oils are not attacked, or decompose into CSu and
amines. Boiling nitric acid oxidizes them to alkylsulphonic acids
with separation of the cyanogen group.

Methyl Thiocyanic Ester, CN.S.CH3, boils at 133°, and has a specific
gravity i.o88 at 0°. When heated to 180-185° '' '^ converted into the isomeric
methyl-isothiocyanic ester, vfith simultaneous polymerization to trithiocyanic ester,
C3N3S3(CH3)3 {Berichte, 18, 2197).

Ethyl Thiocyanic Ester, CN.S.CjH^, boils at 142°. Its specific gravity
equals 1.033 at 0°. It combines directly with the haloid acids.

Isopropyl Thiocyanic Ester, CN.S.CjH,, boils at 152-153°. The isoamyl
ester, CN.S.C5H1 j, boils at 197°.

Allyl Thiocyanic Ester, CN.S.C3H5, is formed when allyl iodide or bromide
acts upon alcoholic potassium thiocyanate at 0°. When heat is applied allyl
mustard oil, CSiN.CgHj, results by molecular transposition. It is produced, loo,
when CNCl acts upon lead allyl mercaptide. A yellow, oily liquid, smelling
somewhat like CNH, and boiling at 161°. Its specific gravity equals 1.071 at 0°.
On boiling it rapidly changes to isomeric allyl mustard oil, CSiN.CjHj ; at ordi-
nary temperatures the conversion is gradual. In the cold zinc and hydrochloric
acid decompose the ester into CNH and allyl mercaptan, C3H5.SH.

The esters of iso thiocyanic acid, CS:NH, are termed mustard oils,
from their most important representative. They may also be con-
sidered as thiocarbimide derivatives. They are formed : —

I. By mixing carbon disulphide with primary (or secondary)
amines in alcoholic, or better, ethereal solution. By evaporation we
get amine salts of alkyl carbaminic acids (see these) : —

OS, + 2NH,.CH3 = CS(^^(™3 CH3).

On adding silver nitrate, mercuric chloride or ferric chloride, to
the aqueous solution of these salts, formed with primary amines,
and then heating to boiling, the metallic compounds first precipi-
tated decompose into metallic sulphides, hydrogen sulphide and
mustard oils, which distil over with steam : —

2CS/^^-^'^^ = 2CS:N.CH3 + Ag,S + H,S.

28o

ORGANIC CHEMISTRY.

Hofmann's mustard oil test for the detection of primary amines
(p. 162) is based on this behavior.

It is advisable to use ferric chloride {Berickte, 8, 108), because mercuric chloride
will desulphurize the mustard oils, and the latter will be transposed into dialkyl
ureas. Iodine, too, forms mustard oils from the amine salts of the dithiocarbaminic
acids, but the yield is small.

2. By distilling the dialkylic thio-ureas (see these) with phosphorus
pentoxide {Berichte, 15, 985) : —

^^\Nh'.CH3 = CS:N.CH3 + NH^-CHj.
Dimethyl Thio-urea. Methyl Mustard Oil.

and by heating the isocyanic esters wlthPjSj {Berichte, 18, Ref. 72) : COiN.CjH,
yields CS:N.C2H5.

The mustard oils are liquids, almost insoluble in water, and pos-
sess a very penetrating odor. They boil at lower temperatures than
the isomeric thiocyanic esters.

When heated with hydrochloric acid to 100°, or with HjO to
200°, they break up into amines, hydrogen sulphide and carbon
dioxide : —

CSiN.C.H^ + 2H,0 = CO, + SH, + NH^.C^H^.

On heating with a little dilute sulphuric acid carbon oxysulphide,
COS, is formed together with the amine. Nascent hydrogen (zinc
and hydrochloric acid) acts as follows : —

CS:N.C2H5 + 2H2 = CSH3 + NH^.C^Hj.

The mustard oils change to urethanes on heating them with abso-
lute alcohol to 100°, or with alcoholic potash. They unite with
ammonia and amines, yielding alkylic thio-ureas (see these). Upon
boiling their alcoholic solution with HgO or HgClj, a substitution
of oxygen for sulphur occurs, with formation of esters of isocyanic
acid. These immediately yield the dialkylic ureas with water (see
p. 274).

Methyl Mustard Oil, CScN.CHj, methyl isothiocyanic ester, methyl thio-
carbimide. It is a crystalline mass, melting at 34° and boiling at 119?.

Ethyl Mustard Oil, CSiN.CjHj, boils at 133° and has a specific gravity
1.019 at 0°. Propyl Mustard Oil, CSrN.C-H,, boils at 153°. Isopropyl
Mustard Oil, CSrN.CjH,, boils at 137°.

Butyl Mustard Oil, CSiN.C^H,, (with normal butyl), boils at 167. Isobutyl
Mustard Oil, CSiN.C^Hg (from isobutylamine), boils at 162°; specific gravity

0.9638 at 14°. The mustard oil having the secondary butyl group, 5|?5\cH,

3 /
occurs in the ethereal oil of Cochlearea officinalis. It boils at 159.5°; its specific
gravity equals 0.944 at 12°.

Isoamyl Mustard Oil, CSiN.CsHu, boils at 183°.

ESTERS OF TRITHIOCYANURIC ACID. 281

The most important of the mustard oils is the common or —
AUyl Mustard Oil, CS:N.C3H5— AUyl Thiocarbimide. This
is the principal constituent of ordinary mustard oil, which is obtained
by distilling powdered black mustard seeds (from Sinapis nigra).
In the latter there is potassium myronate (see Glucosides), which in
the presence of water, under the influence of a ferment, myrosin
(also present in the seed), breaks up into grape sugar, primary
potassium sulphate and mustard oil : —

Ci„Hi,KNO„S, = C,Hi,0, + SO^KH + CS.N.C3H,.

The reaction occurs even at o°, and there is a small amount of
allyl sulphocyanate produced at the same time.

Mustard oil is artificially prepared by distilling allyl iodide or
bromide with alcoholic potassium or silver thiocyanate : —

CN.SK + C3H5I = CS.N.C3H,, + ICI;

a molecular rearrangement occurs here (p. 279). It may also be
obtained by distilling the mercuric chloride of allyl sulphide with
potassium sulphocyanide (p. 143).

Pure allyl thiocarbimide is a liquid not readily dissolved by
water, and boiling at 150.7° ; its specific gravity equals 1.017 at 10°.
It has a pungent odor and causes blisters upon the skin. When
heated with water or hydrochloric acid the following reaction
ensues i —

CSiN.CjH^ + 2H2O = CO2 + SH2 + NH2.C3H5.

It unites with aqueous ammonia to allyl thio-urea. When heated
with water and lead oxide it yields diallyl urea.

ESTERS OF TRITHIOCYANURIC ACID.

Trithiocyanuric acid corresponds to thiocyanic acid, but thio-isocyanuric acid is
not known.

Trithiocyanuric Acid, C3N3(SH)3, is formed in the action of cyanuric chlo-
ride upon sodium sulphide, and may be obtained from its esters by saponification
with sodium sulphide. Acids separate it from its salts in small yellow needles,
which decompose but do not melt above 200° C. Its esters result when cyanuric
chloride and sodium mercaptides interact, and by the polymerization of the thio-
cyanic esters, CN.SR, when heated to 180° with a little HCl. More HCl causes
them to split up into cyanuric acid and mercaptans.

Methyl Trithiocyanuric Ester, C3N3(S.CH3)3, melts at 188° and sublimes
with scarcely any decomposition. Heating with ammonia causes a successive
replacement of the mercaptan residues by amide groups, the final product being
melamine (p. 290) : —

ffS.CHg), r{S.CH3)

C3N3 , C3N3 NH, and C3N3(NH,)3. .

InH, InH^ Melamme.

The esters react similarly with methylamine and dimethylamine {Berickte, 18,

2755)-

24

2S2 ORGANIC CHEMISTRY.

CYANIDES OF THE ALCOHOL RADICALS,
(i) NITRILES.

By this term we understand those derivatives of the alcohol radi-
cals with the cyanogen group, CN, in which the fourth affinity of
carbon is linked to the alcohol radicals.

The following general methods serve for their formation : —

1. The distillation of a potassic alkyl sulphate with potassium
cyanide : —

^°*\K ^' + '^^^ = C2H5.CN + SO,K, ;

or by heating the alkylogens with potassium cyanide in alcoholic
solution to 100° : —

C2H5I + CNK = C2H5.CN + KL

Isocyanides (p. 287) form in slight amount in the first reaction. For their re-
moval shake the distillate with aqueous hydrochloric acid until the unpleasant
odor of the isocyanides has disappeared, then neutralize with soda and dry the
nitriles with calcium chloride.

2. The dry distillation of ammonium salts of the acids with P2O5,
or some other dehydrating agent : —

CHj.CO.O.NH^ — 2H2O = CH3.CN.

Ammonium Acetate. Acetonitrile.

This method of production explains why these cyanides are termed
acid nitriles.

3. By the removal of water from the amides of the acids when
these are heated with PzOs, P2S5 — or phosphoric chloride (see amid-
chlorides, p. 258) : —

CH3.CO.NH2 + PCI5 = CH3.CN + POCI3 + 2HCI,
SCH3.CO.NH2 + P2S5= 5CH3.CN + P2O5 + SH2S.

The nitriles occur already formed in bone-oils.

The nitriles are liquids, usually insoluble in water, possessing an
ethereal odor, and distilling without decomposition. When heated
to 100° with water, they break up into acids and ammonia : —

CH3.CN + 2H2O = CH3.CO.OH + NH3.

This decomposition is more readily effected on heating with acids
or alkalies (p. 211). The acid amides result by the union of the
nitriles with i molecule of water.

CYANIDES OF THE ALCOHOL RADICALS. 283

Nascent hydrogen (sodium amalgam) converts them into amines : —

CH3.CN + 2H2 = CH3.CH2.NH2.

This conversion is most easily accomplished by means of metallic sodium and
absolute alcohol (p. 159 and £erichte,i2, 812).

The nitriles can unite directly with bromine and with the halogen hydrides : —

CH3.CN yields CHj.CBnNH and CHj.CBrj.NHj.

These compounds are identical with those formed by the action of PCI5 upon
the amides (p. 258).

The nitriles form thio-amides with HjS (p. 260) : —

CH3.CN + SH2 = CH3.CS.NH2.

With monobasic acids and acid anhydrides they yield secondary and tertiary
amides (p. 257).

They combine with alcohols and HCl to imido-ethers, R.C:f ^-r, (p. 292) ; thus,

from CNH we get formido-ethers. The nitriles become amidines with ammonia
and the amines (p. 293). Hydroxylamine unites with them to form oxamidines,
or amidoximes (p. 294) . Metallic sodium induces in them peculiar polymerizations ;
bimolecular cyan-alkyls, like dicyan methyl (p. 284), being formed in ethereal
solutions. If, however, sodium acts upon the pure nitriles at a temperature of
150° the products are cyanalkines (thus methyl cyanide, CjHjN, yields cyanmeth-
ine, CgHgNg; ethyl cyanide, C3H5N, yields cyanethine, CjHjjNg) ; these were
formerly classed as tri-molecular cyanides, but really belong to the pyrimidine
or metadiazine bases (see these, and Berichte, 22, Ref. 328).

Formonitrile or Hydrogen Cyanide, H.CN

Acetonitrile " Methyl " CH3.CN

Fropionitrile " Ethyl " C^Hj.CN

Butyronitrile " Propyl " CgHj.CN

Valeronitrile " Butyl " C^Hg.CN, etc.

I. Hydrogen Cyanide, CNH (p. 265), the lowest member of
the series, is to be regarded as formonitrile, because it is obtained
from ammonium formate by the withdrawal of water: —

CHO.O.NH^ — 2H2O = CHN.

Conversely, on boiling with acids or alkalies it yields formic acid
and ammonia. Nascent hydrogen converts it into methylamine,
CH3.NH,.

Acetonitrile, Methyl Cyanide, CH3.CN = C2H3N, is best
obtained by distilling acetamide with P2O5. It is a liquid with an
•agreeable odor, and boils at 81.6°. It is miscible with water, and
burns with a violet light. When boiled with acids or alkalies it
yields ammonia and acetic acid. Nascent hydrogen converts it
into ethylamine.

284 ORGANIC CHEMISTRY.

Dicyan-methyl, C4HgN2, is obtained by the action of sodium upon an ethereal
solution of acetonitrile. It is constituted according to the tautomeric formulas : —

C(NH).CH3 C(NH2).CH3

I °>^ il

CH^.CN CH.CN.

Imido-acetyl Nitrite of

Cyanmethyl. IS-Amidocrotonic Acid.

It crystallizes from ether in colorless needles, melting at 53°. It forms cyan-
acetone with concentrated hydrochloric acid (Berichte, 22, Ref. 325 and 327).

Substituted acetonitriles are obtained from the substituted acetamides by distil-
lation with PgOj. CHjCI.CN boils at 124°; its specific gravity at 11° equals
1.204. CHClj.CN boils at 112°, and its specific gravity is 1.374 at 11°. CClj.
CN boils at 83°; its specific gravity at 12° is 1.439. The direct chlorination of
acetonitrile only occurs in the presence of iodine [Annalen, 229, 163.) Trichloro-
acetonitrile condenses in sunlight to the polymeride, C3N3(CCl3)3, melting at 96°.
Boiling potash changes it to chloroform and cyanuric acid.

3. Propionitrile, Ethyl Cyanide, C3H5N= C2H5.CN. This is also formed
by the action of cyanogen chloride and dicyanogen upon zinc ethyl. It is an
agreeably smelling liquid, which boils at 98°. Its specific gravity equals 0.787.
Salt separates it from its aqueous solution. In all its reactions, it is perfectly analo-
gous to acetonitrile.

Metallic sodium converts ethyl' cyanide in ethereal solution into dicyan-ethyl,

C(NH)C,Hs
CjHjnNj. It is probably iraido-propionyl-cyanethine, | (see above).

CH^.CH^.CN
It is crystalline, melts at 48° and boils at 258°. Acids convert it into propionyl-

CO.CjHj
cyanethine, I {Berichte, 22, Ref. 833 ; 22, Ref. 325). Cyanacetone,

CHj.CHj.CN
CgHijNs = C4N2(CH3)(C2H5)2(NHa), the amido derivative of methyl- diethyl-
pyrimidine (see this), results on heating ethyl cyanide and sodium to 150°.

Chlorine displaces two hydrogen atoms in propionitrile, yielding a-dichlorpro-
pionitrile, CHj.CClj.CN. This is a liquid, boiling at 103-107°, and upon stand-
ing, it polymerizes to the solid (C3H3Cl2N)3. Sodium, or sodium amalgam,
effects the same more rapidly. The product crystallizes in plates, which melt at
73.5°, and decompose when heated. Heated with sulphuric acid and water, both
compounds yield a dichlorpropionic acid, and with alcohol and sulphuric acid its
ester (p. 225). When polymeric dichloropropionltrile is reduced with zinc dust it
yields cyanur-triethyl (p. 285).

4. Butyronitrile, Propyl Cyanide, C3Hj.CN, boils at 118-119°, and has
the odor of bitter-almond oil. Isopropyl Cyanide, CjH^.CN, is formed by the
prolonged heating of isobutyric acid with potassium thiocyanate. It boils at
107-108°.

5. Valeronitriles, C^Hg.N = C^Hj.CN, Butyl Cyanides.

(l) Normal iuiyl cyanide hoi\s 3X 140-141°; its specific gravity is 0.816 at 0°.
(2) hobutyl cyanide boils at 126-128°, and has the odor of oil of bitter almonds;
its specific gravity equals 0.8227 at 0°. (3) Tertiary butyl cyanide is produced
on heating tertiary butyl iodide, (CH3)3CI, with potassio-mercuric cyanide. It
boils at 105-106°, becomes crystalline in the cold, and melts at -(- 16°.

The following higher nitriles may be easily derived from their respective acid
amides by action of P2O5 {Berichte, 15, 1730) : Lauroniirile, Cj2H2 3N(F.P. -|-
4°); myristonitrile, Ci4H2,N (19°); palmilonitrile, C-^^^^ (3'°)) *"'l
stearonitrile, CijHjsN (41°).

NITRO-DERIVATIVES OF ACETONITRILE. 285

Allyl Cyanide, CjHj.CN = CHjiCH.CH^.CN, is not known. The com-
pound produced by heating allyl iodide with potassium cyanide is the isomeric
Propenyl Cyanide, C3H5.CN = CHj.CHiCH.CN. This results from a molecu-
lar rearrangement. It occurs in crude mustard oil.

It is a liquid with an odor resembling that of leeks, boils at 118°, and has a
specific gravity of 0.835 ^t 'S°- It combines with bromine to a dibromide,
CjHjBr^.CN. This becomes a ;3 dibrombutyric acid by saponification {Berichte,
22, Ref. 49S). It yields nothing but acetic acid when oxidized with a chromic
acid mixtvffe. It yields crotonic acid when boiled with alcoholic potash (p. 238).

Tricyanalkyls or Cyanur-trialkyls. Although the cyanogen derivatives fre-
quently condense to tricyanogen or cyanuric compounds, yet tricyanhydride, or
cyanuric acid, is not known. Its alkyl derivatives exist.

Cyanuric Triethyl, C3N3(C2H5)3, results from the action of zinc dust upon
polymeric a-dichloropropionitrile (p. 284), or zinc dust and acetic acid (Berichte,
22, 1446 ; 20, Ref. 55). It is very volatile, and has a narcotic odor. It melts at
29° and boils at 119°^. It is decomposed into propionic acid and ammonia (Be-
richte, 23, 766) by hydrochloric acid at the ordinary temperatures.

A general method for the preparation of diphenylated cyanur-alkyls consists in
the action of AlCl, upon a mixture of benzonitrile and the chlorides of fatty acids.
The nitriles of. fatty acids do not yield analogous compounds {Berichte, 23, 765).

NITRO-DERIVATIVES OF ACETONITRILE.

In this section a class of compounds will be considered which,
although not directly obtained from acetonitrile, are yet regarded
as derivatives of it [Berichte, i6, 2419).

Nitro-acetonitrile, .QHoNjO^ = CH2CN02).CN, or hypothe-
tical fulminic acid, is considered the basis of the so-called fulminates,
derived from it by the introduction of metals for two hydrogen
atoms. The influence of the negative groups, CN and NO2, ex-
plains the acid nature of acetonitrile (p. 266).

A compound having the composition of nitro-acetonitrile has been obtained by
the action of concentrated sulphuric acid upon ammonium fulminurate. It is a
crystalline solid, insoluble in water, melts at 40°, and volatilizes very readily
(Berichte, 9, 783).

Mercury Fulminate, C,HgN,0, = CHg(N02).CN(?) {Be-
richte, 18, Ref. 148), is formed by heating a mixture of alcohol,
nitric acid and mercuric nitrate.

I part mercury is dissolved in 12 parts nitric acid (sp. gr. 1.345), S-5 parts
alcohol of 90 per cent, added, and the whole well shaken. After a little time, as
soon as energetic reaction commences, 6 parts alcohol more are gradually added.
At first metallic mercury separates, but subsequently dissolves and deposits as
mercuric fulminate in flakes (Berichte, g, 787). Modifications of this method may
be found in Berichte, 19, 993 and 1370.

Fulminating mercury crystallizes in shining, gray-colored prisms,
which are tolerably soluble in hot water. It explodes violently on

286 ORGANIC CHEMISTRY.

percussion and also when acted upon by concentrated sulphuric
acid. Hydrogen sulphide precipitates mercuric sulphide from its
solution, the liberated fulminic acid immediately breaking up into
CO2 and ammonium thiocyanate. Concentrated hydrochloric acid
evolves COj and yields hydroxylamine hydrochloride, a procedure
well adapted for the preparation of hydroxylamine {Berichte, 19,
993)-

Bromine converts mercuric fulminate into dibromnitroacetonitrile , CBr2(N02).
CN, which forms large crystals, soluble in alcohol and ether, and melting at 50°.
Iodine produces the iodide, Cl2(N02).CN; colorless prisms, melting at 86°.
Chlorine gas changes mercuric fulminate into HgCl2, GNCl and chloropicrin.
Ammonia in aqueous solution decomposes it into urea and guanidine.

On boiling mercury fulminate with water and copper or zinc, metallic mercury
is precipitated and copper and zinc fulminates (C2CUN2O2 and CjZnNjOj) are
produced. Silver fulminate, C2Ag2N202, is prepared after the manner of the
mercury salt, and resembles the latter. Potassium chloride precipitates from hot
silver fulminate one atom of silver as chloride and the double salt, C2AgKN202,
crystallizes from the solution. Nitric acid precipitates from this salt acid silver
fulminate, C2AgHN202, a white, insoluble precipitate.

Dinitro-acetonitrile, CH(N02)2.CN. Its ammonium salt is produced when
hydrogen sulphide acts upon trimtro-acetonitrile : —

C(N02)3.CN + 4H2S = C(NHJ(N02)2.CN + 4S + 3H20.

Sulphuric acid liberates the nitrile from this salt, and it may be withdrawn from
the solution by shaking with ether. It forms large, colorless crystals and con-
ducts itself like a monobasic acid. The silver salt, C2Ag(N02)2N, explodes
very violently. It forms C2Br(N02)2N with bromine.

Trinitro-acetonitrile, C2(N02)3N, is obtained by the action of a mixture of
concentrated nitric and sulphuric acids upon potassium fulminate. It separates out
as a thick oil, with evolution of CO2, and on cooling solidifies.

Trinitro-acetonitrile is a white, crystalline, camphor-like mass, melting at 41.5°,
and exploding at 200°- It volatilizes at 60° in an air current. Water and alcohol
decompose it, even in the cold, into CO 2 and the ammonium salt of nitroform
(p. 112).

Fulminuric Acid, C3N5.O3H3, or Isocyanuric Acid.. Its alkali salts are
obtained by boiling mercuric fulminate with potassium chloride or ammonium
chloride and water. In its preparation 60-75 grams of mercuric fulminate are
heated with 60 c.c. of a saturated ammonium chloride solution, and 700-800 c.c.
of water, until mercuric oxide no longer separates. The solution will then con-
tain HgCl2 and ammonium fulminurate. Ammonium hydrate is now employed
to throw out all the mercury, when the solution is filtered and concentrated to
crystallization. To obtain the free acid, add lead acetate to the solution of the
ammonium salt, decompose the lead salt with hydrogen sulphide, and evaporate
the filtrate down to a small bulk.

Fulminuric acid is an indistinctly crystalline mass, soluble in water, alcohol and
ether, and deflagrating at 145°. It is a monobasic acid, yielding finely crystallized
alkali salts. Especially characteristic is the Cuprammonium salt, CjNjOjH,
(CuNHg), which precipitates from the aqueous solution of the acid or its alkali

ISOCYANIDES OR CARBYLAMINES. 287

salt when boiled with ammoniacal copper sulphate. It consists of glistening dark
blue prisms. Mercury fulminurate is produced when mercury fulminate is heated
with alcoholic ammonia. *

Trinitroacetonitrile is formed by the action of a mixture of concentrated nitric
and sulphuric acids upon fulminuric acid : —

C3N3O3H3 + 2NO3H = q{N0,)3N + N H3 + CO2 + H,0.

The constitution of fulminuric acid is not known. Consult Berichte, ig, Ref.
22, upon an isomeric isofulminuric acid.

(2) ISOCYANIDES OR CARBYLAMINES.

These constitute a series of compounds parallel to, and isomeric
with, the nitriles or alkylcyanides. They are obtained: —

1. By digesting chloroform and primary amines with alcoholic
potash (A. W. Hofmann) : —

C2H5.NH2 + CCI3H = CjHj.NC + 3HCI.

The carbylamine test of Hofmann for detection of primary
amines is based on this (p. 162).

2. By action of the alkyl iodides upon silver cyanide (p. 269)
(Gautier) :—

C^HJ + NCAg = QHj.NC + Agl.

Preparation. — Heat 2 molecules of silver cyanide with I molecule of the iodide,
diluted with J^ volume of ether, in sealed tubes to I30°-I40° for several hours.
Water and potassium cyanide {yi, part) are added to the product (a compound of
the isocyanide with silver cyanide) and the whole distilled upon a water bath
{Annalen, 151, 239).

3. The isonitriles are produced, too, in slight quantity, in the
preparation of the nitriles from alkyl sulphates and potassium cyan-
ide (p. 282).

The carbylamines are colorless liquids which can be distilled,
and possess an exceedingly disgusting odor. They are sparingly
soluble in water, but readily soluble in alcohol and ether.

While, in the nitriles, the carbon of the cyanogen group is firmly
attached to the alcohol radicals, and nitrogen splits off readily as
NH3, in all decomposition reactions of the isonitriles nitrogen
remains in combination with the alcohol radical. Hence, in the
latter we assume the presence of the isomeric isocyanogen group, in
which nitrogen figures as a pentad : —

CH3 _ N= C and CH3 _ C = N.
isocyanide. Cyanide.

The isocyanides are characterized by their ready decomposition
by dilute aqids into formic acid and amines : —

C2H5.NC + 2H2O = C2H5.NH2 + CHjOj.

288 ORGANIC CHEMISTRY.

The same decomposition occurs when they are heated with water
to 1 80°. When oxidized by mercuric oxide they become isocyanic
esters (p. 274) : —

C2H5.NC + HgO = C2H5.N;CO + Hg.

The isocyanides, like the cyanides, form crystalline compounds
with HCl ; water decomposes these into formic acid and amine
bases (p. 283). They pass into thio-formamides by their union
with H2S (p. 260).

Methyl Isocyanide, CH3.NC, methyl carbylamine, boils at S9° and dissolves
in 10 parts of water. When heated with water it decomposes.

Ethyl Isocyanide, CjHj.NC, is an oily liquid which swims upon water and
boils at 79°.

Isoamyl Isocyanide, CjHjj.NC, boils at 137° and swims on water.

AUyl Isocyanide, C3H5.NC, boils near 106°, and has a specific gravity of
0.796 at 17°.

AMIDE DERIVATIVES OF CYANOGEN.

Cyanamide, CN.NHj, or carbodiiraide, C(NH)2, is formed by
the action of chlor- or brom-cyan upon an ethereal or aqueous solu-
tion of ammonia (JBerichte, 18, 462), and also by the desulphurizing
of thio-urea by means of mercuric chloride or lead peroxide {Berichte,
18,461):—

•^^XNHj + ^^SO = CN^Hj + HgS + H^O.

It forms colorless crystals, easily soluble in water, alcohol and
ether, and melting at 40°. If heated it polymerizes to dicyan-
diamide and tricyan-triamide (melamine). It forms salts with
strong acids, but these are decomposed by water. Again it unites
with metals to salts. An ammoniacal silver nitrate solution throws
down a yellow precipitate, CNjAgj, from its solutions. Copper sul-
phate precipitates black CNjCu.

Such metallic compounds are obtained directly by heating the
salts of isocyanic acid with the alkaline earths and the heavy
metals : —

(C0:N)2Ca = CNjCa + CO^.

By. the action of sulphuric acid or hydrochloric acid, it absorbs
water and becomes urea : CN2H2 -}- H2O = CO(NH2)2. H2S con-
verts it into thio-urea, and NHj into guanidine (p. 294).

The transpositions and syntheses of cyanamide give no positive
evidence as to whether it should be considered as amide, CN.NH2,
or carbodiimide, HN:C:NH. Perhaps the. forms are tautomeric.
However, two isomeric varieties of alkyl derivatives d(J exist (same
as with cyanic acid).

AMIDES OF THE DICVANIC ACIDS. 289

Alkylic Cyanamides are obtained by letting cyanogen chloride act upon primary
amines in ethereal solution : —

NHj.CHj + CNCl = NH(CH3).CN + HCI.

They may be prepared also by heating the corresponding thio ureas with mer-
curic oxide and water : —

CS^NH^ "' + ^g° = CN.NH(CH3) + HgS + H,0.

Methyl Cyanamide, CNjH(CH3), and Ethyl Cyanamide, CN2H(CjH(_
are noncrystallizable thick syrups with neutral reaction. They are readily con
verted into polymeric isomelamine derivatives.

Diethyl Cyanamide, CN.N(C2H5)j, is prepared by the interaction of silver
cyanamide and ethyl iodide. It is a liquid, boiling at 186-190°. Boiling hydro-
chloric acid resolves it into COj, NH3 and diethylamine, NIKCjHj)^.

Allyl Cyanamide, CNjHfCjHs), called Sinamine, is obtained from allylthio-
urea. It is crystalline and polymerizes readily into triallylmelamine (see below).

5;>

Dicyanamide, NH(CN)2, is only known in its salts. The potassium salt,
C2N3K, is obtained by heating potassium cyanide with paracyanogen or with mer-
curic cyanide (Berichte, 13, 2202). It crystallizes in thin needles. Silver nitrate
precipitates a white silver salt, CjNjAg, from its solution.

AMIDES OF THE DICYANIC ACIDS.

Cyanamide, CN.NHj, may be considered as the amide of normal cyanic acid,
CN.OH, and carbodi-imide the imide of hypothetical isocyanic acid, HN:CO (p.
271). Similarly, there may be derived from the latter acid two isomeric dicyanic
acids : —

HO.C/^ JCOH and Co/^H\co
Normal Dicyanic Acid. Isodicyanic Acid.

and their amide derivatives : —

H,N.c/N\c.NH, and HN:C<^^H\c^^jj
Dicyandiamide, Isodicyandiimide.

These are probably tautomeric forms and only isomeric in their alkyl derivatives
(not yet known).

Dicyandiamide, C2N4H4, Param, results from the polymerization of cyanamide
upon long standing or by evaporation of its aqueous solution. It crystallizes in
leaflets which melt at 205°. It is insoluble in ether. Its structure probably agrees

with the formula, NHiC^^^jj'i^^jg- Hence, it can be called cyanguanidine

(Berichte, 16, 1464; 18, 3106). However, these reactions (together with guanyl-
urea), are explained by the amide or imide formulas (Berichte, 19, 2086).

Dicyandiamidine, CjHgNp = NH:C(^^^2(.q j^jj (guanyl urea), is formed
by the action of dilute acids upon dicyandiamide or cyanamide, or by fusing a
guanidine salt with urea. It is a strongly basic, crystalline substance, and absorbs

290 ORGANIC CHEMISTRY.

COj. When digested with baryta water it decomposes into CO2, NH,, an-d urea
(Berichie, zo, 68).

By boiling dicyandiamide with baryta water it is converted into Amido-dicy-

anic Acid, CO;('?JS'^C:NH (?). This crystallizes in needles, and when heated

with sulphuric acid changes to biuret.

AMIDES OF THE CYANURIC ACIDS.

There are also amide and imide derivatives of the cyanuric acids. These are
probably tautomeric and only isomeric in the alkyl compounds: —

OH NH, NHj NHj

I I I I

c c c c

/% /\ /\ /%

NN NN NN NN

II I II I II II

HO.C CO.H HO.C C.OH HO.C C.NH^ H^N.C C.NHj

\^ \^ \<^ \<^

N N N N

Normal Cyanuric Cyanurmonamide Cyanurdiamide Cyarurtriamide,

Acid, Ammelide. Ammeiine. Melamine.

O NH NH NH

II II II II

c c c c

/\ /\ /\ /\

HN NH HN NH HN NH HN NH

II II II II

OC CO OC CO OC C:NH HN:C C:NH

\ / \ X \ / \ /

N N N N

H H H H

Isocyanuric Isocyanurmonamide Isocyanurdiimide Isocyanurtriimide

Acid. Melanuric Acid. Isoammeline. Isomelamine.

Melamine, CgHgN,, ^= C3N3(NH2)3 (see above), Cyanuramide, is produced
by:—

The polymerization of cyanamide or dicyandiamide on heating to 150° (together
with melam); by heating methyl trithiocyanuric ester to 180° with concentrated
ammonia ; and by heating cyanuric chloride to 100° with concentrated ammonia : —

C3N3CI3 + 6NH3 = C3H3(NH,)3 + sNH.Cl.

It is obtained from crude melam (p. 291) by extraction with water and precipi-
tation with soda [Berichte, ig, Ref. 345) ; or more easily from cyanuric chloride
(Hofmann, Berichie, 18, 2765).

Melamine is nearly insoluble in alcohol and ether. It crystallizes from hot
water in shining monoclinic prisms. It sublimes on heating and decomposes into
melam and NH3. It forms crystalline salts with I equivalent of acid.

On boiling with alkalies or acids melamine splits off ammonia and passes suc-
cessively into ammeiine, C3H5N5O = C3N3(NHj)2.0H (a white powder insoluble
in water, but soluble in alkalies and mineral acids) {Berickte, 21, Ref 789) ;
ammelide, CjH^N^Oj = C3N3(NH,^)(OH)2, a white powder that forms salts with
both acids and bases, and finally cyanuric acid, C3N3(OH}3 — {Berichie, 19, Ref.
341). Potassium cyanate is directly formed by fusing melamine with KOH.

COMPLEX CYANIDES. 29 1

Melanurenic Acid, CgH^N^Oj, from melam and melem (p. 292) wlien heated
with concentrated HjSOt [Berichte, ig, Ref. 244), and from dicyandiamide by
the addition of COj (on heating (NH^)2C03), is a white amorphous powder, soluble
in alkalies and acids with formation of salts, and breaks off into NHg and cyanuric
acid when boiled with alkalies and acids. It is probably identical with ammelide
(Berichte, 19, Ref. 341), or it is the isomeric isocyanurimide {Berichte, 18, 3106).
According to its salts melurenic acid appears to have the doubled formula, CgHg
N8O4 (Berichte, 19, Ref. 245).

Thioammeline, C3H5N5S = (CN)3(NHj)2.SH, is obtained from dicyandiamide
by the addition of thiocyanic acid, CN.SH, and from cyanuric chloramide,
C3N3{NH2)2C1, by the action of potassium sulphydrate. It corresponds to amme-
line (see above) [Berichte, 20, 1059). Its esters result from heating trithiocy-
anuric esters with ammonia (p. 281).

ALKYL DERIVATIVES OF MELAMINE.

While melamine is only known in one form as cyanurtriamide, two series of
isomeric alkyl derivatives exist — obtained from normal melamine and hypothetical
isomelamine : —

(I) C3N3(NHR)3 and C3H3(NR,)3. (2) C3N3H3(NR)3.

Normal Alkylmelamines. Isoalkylmelamines.

These are distinguished from each other not only in the manner of their prepa-
ration but also in their transpositions.

(i) Normal Alkylmelamines are obtained from the trithiocyanuric esters,
C3N3(S.CH3)3, and from cyanuric chloride, CSN3CI3, upon heating with primary
and secondary amines {Berichte, 18, Ref. 498) : CgNjCla + 3NH(CH3)2 r=

C3N3(NpJ;') + 3HCI. Heating with hydrochloric acid causes them to split

up into cyanuric acid and the constituent alkylamines.

Trimethylmelamine, C3N3(NH.CH3)g, dissolves readily in water, alcohol
and ether. It melts at 115°. Triethylmelamine, C3N3(NH.C2H5)3, crystal-
lizes in needles and melts at 73-74° C.

Hexamethylmelamine, C3N3[N(CH3)2]3, consists of needles, melting at
171° C. Hexaethylmelamine, C3H3[N(C2H5)2]3, is a liquid, and is decom-
posed by hydrochloric acid into cyanuric acid and 3 molecules of diethylamine.

(2) Alkylisomelamines are formed by the polymerization of the alkylcyan-
amides, CN.NHR, upon evaporating their solutions (obtained from the alkyl-
thioureas on warming with mercuric oxide and water). They are crystalline bodies.
When heated with hydrochloric acid they yield cyanuric esters and ammonium
chloride [Berichte, 18, 2784).

Trimethylisomelamine, C3N3H3(N.CH3)3 + sH^O, melts at 179° when
anhydrous. It sublimes about 100°. Triethylisomelamine, C3N3H3(N.C2H5)3
+ 4H2O, consists of very soluble needles. Consult Hofmann, Berichte, 18, 3217,
for the phenyl derivatives of the mixed melamines (also amide and imide bodies).

COMPLEX CYANAMIDES.

Melam, C(;H<,N„. Formed on rapidly heating CNSNH4 or CNSK to 200°
with ammonium chloride. Melam and sulphocyan-melamine are produced at the
same time. The latter dissolves on boiling with water, while melam and melem
constitute the residue, and are separated by alcohol, the first being soluble in this

292 ORGANIC CHEMISTRY.

solvent {Berichte, ig, Ref. 340). It is a granular powder insoluble in water.
Boiling alkalies or acids decompose it into NH3 and ammeline. Its constitution
is, therefore, probably (NHj)jC3N3(NH)C3N3(NHj)(l. c).

Melem, CgHgNi„ (see above), decomposes on boiling with alkalies or adds
into NH3 and ammelide. Its composition is probably (NH2)C3N3(NHj)C3N3(NHj).

Mellon, C3H3N9 = C3N3(NH)3C3N3, is produced on igniting ammonium sul-
phocyanide, melam, ammeline, etc. Boiling acids decompose it into NH3 and
cyameluric acid, C5H3N,03 {Berichte, 19, Ref. 340).

IMIDO-ETHERS, AMIDINES AND OXAMIDINES.

The imido-ethers, the amidines, the oxamidines and guanidine (p. 294) are
intimately related to the nitriles and cyanamides.

(i) The Imido-Ethers, R-C^qr C'^^''' '^^^ i^\'^), are produced by the
action of HCl upon a mixture of a nitrile with an alcohol (in molecular quantities)
(Pinner, Berichte, 16, 3S3, 1654) : —

CH3.CN + CjjHj.OH + HCl = CH3.C:^^^-^^'

Acetimido-ether.

Acetimido-ethyl Ether, when liberated from its HCl-salt by means of NaOH,
is a peculiar-smelling liquid, boiling at 97°. Its HCl-salt crystallizes in shining
leaflets, and like the other imido-ethers is readily decomposed by heat (with forma-
tion of acetamide and ethyl chloride).

The formimido-ethers are obtained from CNH, alcohol and HCl by a reaction
analogous to that given above : —

HCN + C2H5.OH -f HCl = HC^Q^-][^^'

Formimido-ethyl Ether.

These are only known in their salts, which suffer various noteworthy transforma-
tions. Upon standing with alcohols they pass into esters of orthoformic acid (see
this) :—

y^NH HCl /O.CH3

HCf i^:"'"^' + 2CH3.OH = HC— O.CH3 + NH.Cl.

\^-^2"5 \O.CjH5

They yield amidines with ammonia and amines (primary and secondary) :. —

^^^\0™/ + NH3 = Hc(^NH^jjQ ^ C,H,.OH.

All the other imido ethers react similarly. With hydroxylamine they yield the
acidoximes {Berichte, 17, 185), corresponding to the aldoximes and acetoximes: —

^<^.?;^?+ ^H,.OH = RC(N(9H)^ + NH.Cl.

See Berichte, 17, 2002, for the phenylhydrazine derivatives of the imido-ethers.

IMIDO-ETHERS, AMIDINES AND OXAMIDINES. 293

/^^ imido-thio-ethers correspond to the imido-ethers. They are obtained by
the action of HCl upon nitriles (of the benzene series), and mercaptans : —

C,H,.CN + HS.C,H, = C^H^.C^gNH^^ _

further, when the thio-amides (of the benzene series) are treated with alkyl-iodides
{Benchte, 15, 564) :—

C,H,.CS.NH, + C,H,I = C,H,.C^|[H ^^ ^ ^^

This class of compounds has a constitution similar to that of the isothioaraides
(p. 260).

(2) The amidines, K.-C/j^j^ , whose hydrogen atoms can be replaced by
alkyls, are produced : —

1. From the imid-chlorides, thio-amides, and isothio- amides (p. 255) {Berichte,
i5, 146), by the action of ammonia or amines (primary and secondary) : —

CH,.CC1:N(C.H,) + NH,.CH3 = CH3.c(N^^3^^ + HCI,
C,H,.CS.NH, + NH3 = C,H,.C^NH^ V H,S.

2. From the nitriles by heating them with ammonium chloride, or HCl-
amines : —

CH3.CN + NH,.C,H, = CH3.C^N^^»^5 .

3. From the amides of the acids when treated with HCl {Berichte, 15, 208) :—

2CH3.CO.NH, = CHjC^^g^ + CH3.C0,H.

4. From the imido-ethers (p. 292) when acted upon with ammonia and amines
{Berichte, 16,1647 ; 17. 179)-

The amidines are mono-acid bases. In a free condition they are quite unstable.
The action of various reagents on them induces water absorption, the imid-group
splits off, and acids or amides of the acids are regenerated : —

^^'■^\NH, + ^2° = CH3.CO.NH, -f NH3.

HjS causes the elimination of the imid- or amid-group from the amidines, and
thus converts them into thio-amides (p. 260). CSj effects the same, sulpho-cyanic
acid, CNSH, and mustard oils, CS.NR, being simultaneously produced [Annalen,
192, 30). Hydroxylamine supplants the imid-group in them with the oximid-
group, N.OH, with formation of oxamidines, or amidoximes (see these).

Aceto-acetic ester, or acetic anhydride {Berichte, 22, 1 600) , converts the amidines
into pyrimidines or raetadiazine derivatives (see these). They also combine with
phenyl cyanates, with diazo compounds, with chloral, and other aldehydes (see
benzamidine, and Berichte, 22, 1607).

Formamidine, CNjH, =CHf :^TT (Methenylamidine), is only known

294 ORGANIC CHEMISTRY.

in its salts. The HCI-salt, CNjH^.HCI, is obtained from CNH.HCl (p. 267) on
heating it with alcohol : —

2CNH.HCI + 2C2H5.OH = CNjH^.HCl + CjHsCl + CHO2.C2H5.

It consists of very hygroscopic needles, melting at 81°, and is decomposed into
NHg and formic acid by the alkalies.

Acetamidine, C2H(;N2 = CH3.C^j,pj (Acediamine), is obtained by heat-
ing acetamide in a stream of HCl. Its hydrochloric acid salt crystallizes in large,
shining prisms that melt at 165°- The acetamidine, separated by alkalies, reacts
strongly alkaline and readily breaks up into NH3 and acetic acid. The higher
amidines and their alkyl derivatives are easily obtained by the usual methods \Be-
richte, 17, 178).

The so-called anhydro-bases and ethenyl derivatives of the benzene series (see
these) are classed with the amidines.

Methenyl-amidoxime, CH^NjO ^ CH^„ „?T (Isuretine), is isomeric

with urea, CO(NH2)2.

It appears on evaporating the alcoholic solution of hydroxylamine and hydrogen

cyanide. It crystallizes in rhombic prisms, similar to those of urea, and melts with

. partial decomposition at I04°-I0S°. It reacts alkaline and forms crystalline salts

with I equivalent of the acids. On heating the solutions of its salts, the latter

decompose into formic acid, ammonia and hydroxylamine.

Ethenyl-amidoxime, C^^^O = CH3.C<^Sq|t' from acetonitrile and

hydroxylamine, is very soluble in water, crystallizes in needles, and melts at 135°.
Warm water breaks it up into HjN.OH and acetamide. Acid anhydrides or
chlorides convert the amidoximes into azoximes {Berichte, 18, 1062 ; see Benzenyl
amidoxime).

(3) Oxamidines, or Amidoximes, R.c/-xtVt . These may be considered

amidines, in which one H-atom of the amid- or imid-groups is replaced by hy-
droxyl. They arise : —

1 . From the action of hydroxylamine upon amidines.

2. By the addition of hydroxylamine to the nitriles {Berichte, 17, 2746) : —

CH3.CN + NH,OH = CHj.c/^l^^jj .
Acetonitrile. Ethenylamidoxime.

3. From the addition of hydroxylamine to thio-amides (^Berichte, ig, 1668) : —

CH3.CS.NH, -f NH.OH =CH3.C/^H|^ ^ H,S.

The amidoximes are crystalline, very unstable bodies, which readily break up into
hydroxylamine and acid amides or acids.

Guanidine, CNsHj = HN:C(^^!I' carb-diamid-imide, is an

amidine of carbonic acid. It may also be considered as urea,
CO(NH2)2, in which the oxygen has been replaced by the imid-

IMIDO-ETHERS, AMIDINES AND OXAMIDINES. 295

group. It was first obtained by the oxidation of guanine with hy-
drochloric acid and potassium chlorate, hence its name. It is formed
synthetically by heating cyanogen iodide and NH^ and fromcyana-
mide (p. 289) and ammonium chloride in alcoholic solution at
100°:—

/NH2
CN.NHj + NHj-HCl = C=NH.HC1.

This is analogous to the formation of formamidine from HCN.
It is also produced by heating chloropicrin or esters of orthocar-
bonic acid, with aqueous ammonia, to 150° : —

CCI,(N02) + 3NH3 = CN3H5.HCI + aHCl + NO^H.

It is most readily prepared from the sulphocyanate salt, which is made by pro-
longed heating of ammonium sulphocyanate to l8o°-l90°, and the further trans-
position of the thio urea that forms at first : —

^S:n)cS = g^N\c.NH.CNSH + H,S.

To get the free guanidine from this salt, evaporate the aqueous solution with an
equivalent quantity of potassium carbonate, extract the potassium thiocyanate from
the mass with boiling alcohol, and convert the residual guanidine carbonate into
sulphate, and from this liberate the guanidine by means of baryta {Berichte,T, 92).

The crystals of guanidine are very soluble in water and alcohol,
and deliquesce on exposure. It is a strong base, absorbing COj
from the air and yielding crystalline salts with i equivalent of the
acids. The nitrate, CN3H5.HNO3, consists of large scales, which
are sparingly soluble in water. The HCl-salt, CN3H5.HCI, yields a
platinum double salt, crystallizing in yellow needles. The carbo-
nate, (CN3H5)2.H2C03, consists of quadratic prisms, and reacts alka-
line. The sulphocyanate, CN3H5.HSCN, crystallizes in large leaf-
lets, that melt at 118°.

Guanidine is most readily detected by converting it into guanyl urea (p. 289)
{Berichte, 20, 71).

The substituted guanidines, resulting from the introduction of alcohol radicals,
are obtained by reactions analogous to those employed in the preparation of guani-
dine, viz., the heating of cyanamide with the HCl-salts of the primary amines : —

CN.NH2 -f NHj,(CH3).HCl = CN6H^(CH3).HC1.

Methyl Guanidine, CN3H4(CH3). Silver oxide separates this from the HCl-
salt. It forms a deliquescent, crystalline mass. Its salts with I equivalent of acid
crystallize quite well. It is also produced on boihng creatine with mercuric oxide
and water.

Triethyl Guanidine, CN3H2(C2H5)3, is obtained by boiling diethyl thio-urea

296 ORGANIC CHEMISTRY.

and ethylamine in alcoholic solution with mercuric oxide whereby sulphur is
directly replaced by the imid-group (see thio-ureas) : —

•^^XNH.c'h', + NH,.C,H, + HgO =
C,H,.N:C/^g;^^g^ + HgS + H,0.

Vice versa, the alkylic guanidines, when heated with CSj, have their imid-
group replaced by sulphur (same as with the amidines, p. 293), with formation of
thio-ureas.

The guanidine-benzene derivatives are especially numerous. Acid residues may
also replace the hydrogen of guanidine ; these derivatives will receive attention
when the urea compounds are described.

Guanidine also forms salts with the fatty acids. When these are heated to
220-230°, water and ammonia break off, and the guanamines result. These are
produced by the union of I molecule of acid and 2 molecules of guanidine. They
are mono-acids, and very probably have a structure similar to that of the amidines
p. 293). Formo-guan amine, C3H5N5, from guanidine formate, ar^/o-^«a«<7»2!»^,
C^HjNj, from the ^.ceX3X&,propio-guanamine,Q^'R^'^^,butyro- and isobutyro-
guanamine, C^HjjNj, etc., [Berichte, 9, 454) belong here.

DIVALENT COMPOUNDS.

The introduction of two monovalent groups into the hydrocarbons
for two hydrogen atoms produces the divalent compounds.

The replacement of hydrogen by two hydroxyl groups yields the
divalent alcohols or glycols, which we can also term dialcohols (see

p. 114):—

,OH CH..OH
C,H / = I

\0H CH2.OH

Ethylene Glycol.

By replacing two hydrogen atoms in the glycols by oxygen, we get
the divalent (dihydric) monobasic acids, containing one carboxyl
and one hydroxyl group : —

,0H CH„.OH
C,H,0( = I

^OH CO.OH

GlycoUic Acid.

The substitution of two additional hydrogen atoms by oxygen yields
the divalent, dibasic acids, with two carboxyl groups : —

-OH CO.OH
^^OH CO.OH "

c,o,/

Oxalic Acid,

Numerous related derivatives attach themselves to these three prin-
cipal groups of divalent compounds.

DIHYDRIC ALCOHOLS OR GLYCOLS. 297

The divalent compounds contain either two similar reactive atomic groups, like
the dialdehydes (glyoxal), the diketones (diacelyl), the diamines (ethylene diamine),
etc., and hence manifest the typical properties of the monovalent compounds
doubly, or they contain two different typical atomic groups, present in the same
molecule, and thus present simultaneously the typical characters of different groups
of compounds. Derivatives possessed of this mixed function are in addition to
the oxyacids or alcohol-acids (see above) : the aldehyde alcohols (glycol aldehyde,
CH2(0H).CH0), the ketone alcohols (acetyl carbinol, CHj.CO.CHj.OH), the
aldehyde acids (glyoxylic acid), the ketonic acids, the amido-acids, etc.

DIVALENT (DIHYDRIC) ALCOHOLS OR GLYCOLS.

Wilrtz obtained the glycols in 1856, from the haloid compounds
of the alkylens, C^H^^. They are formed as follows : —

1. By heating the alkylen haloids (p. 100) with silver acetate (and
glacial acetic acid), or with potassium acetate in alcoholic solution : —

C,H,Br, + 2C,H30,.Ag = C.H./g-^^gaO ^ ^^gBr.

Ethylene Diacetate.

The resulting acetic esters are purified by distillation, and then
saponified by KOH : —

^^'^^xacfn^o + 2KOH = c,H,/°g + 2C,H30,K.

Generally in using potassium acetate, a mixture of di-acetate and mono-acetate
is produced with free glycol. The mixture is saponified writh KOH, or Ba(0H)2.
A direct conversion of alkylen haloids into glycols may be attained by heating
them with water and lead oxide, or sodium and potassium carbonate (p. 1 19).
When ethylene bromide is heated for some time with much water above 100° it
is completely changed to ethylene glycol, whereas with little water aldehyde
results (Annalen, 186, 393).

2. Another procedure consists in shaking the alkylens, CnH^n, with aqueous
hypochlorous acid, and afterwards decomposing the chlorhydrins formed with
moist silver oxide : —

C,H^ + ClOH = C,H,/g^jj and

The glycols appear in small quantities when hydrogen peroxide acts on the

defines CnH.n : —

C,H, + H,0, = C,H,(OH),.

3. By the oxidation of the olefines in alkaline solution (p. 82 and Berichte,
21, 1230) with potassium permanganate : —

CH^ CH^.OH

II +0 + H20=. I

CH, CH.jOH

25

298 ORGANIC CHEMISTRY.

Isobutylene, (CH3)2C:CH, yields isobutylene glycol, (CH3)aC(OH).CH2.0H,

etc

From the method of producing glycols out of the alkylens, C^H^'', by means
of their addition products, it would appear that in the glycols the hydroxyl groups
are bound to ^wo different Cix\>aa atoms. One carbon atom can link but one OH
group. Thus from ethidene chloride, CHj.CHClj, we cannot obtain the corre-
sponding glycol, CH3.CH(OH)2. When dihydroxides'do form, water separates
and the corresponding anhydrides — the aldehydes (p. 1 88) — result : —

CHj.Ch/^^ yields CH3.CHO + H^O.

The union of two OH groups to one carbon atom is more stable if the neighboring
carbon atom be attached to negative elements. Thus the rather stable hydrate of
chloral, CCI3.CHO + H^O, can be viewed as a dihydroxyl derivative (as tri-

chlorethidene glycol), CCl3.CH<f„TT (compare glyoxylic and mesoxalic acids).

Such hydroxyl groups are usually not capable of further exchange, as is the case
with those in the glycols.

While, therefore, the union of two hydroxyl groups to one carbon atom is but
feeble, two oxygen atoms may be firmly attached, if they are linked at the same
time with alcoholic or acid radicals, as in —

PH Th/ 2 5 and CH Ph/ 2 3O

Ethidene-diethylate. Ethidene-diacetate.

The possible isomerisms for the glycols are deduced from the
corresponding hydrocarbons, according to the ordinary rules, with
the single limitation that but one OH group can be attached to
each carbon atom. Thus two glycols, C3He(OH)2, are derived from
propane : —

CH3.CH(OH).CH2.0H and CH2(OH).CH2.CH2.0H.

a-Propylene Glycol. |3-Propylene Glycol.

The first contains both a primary and a secondary alcohol group
(p. 118), and therefore can be caWtA primary-secondary glycol ; the
second has two primary alcoholic groups, and represents a di-primary
glycol, etc. The higher glycols are similarly named.

The glycols are neutral, thick liquids, holding, as far as their
properties are concerned, a place intermediate between the monohy-
dric alcohols and trihydric glycerol. The solubility of a compound
in water increases according to the accumulation of OH groups in
it, and it will be correspondingly less soluble in alcohol, and espe-

DIVALENT ALCOHOLS OR GLYCOLS. 299

cially in ether. There will be also an appreciable rise in the boiling
temperature, while the body acquires at the same time a sweet taste,
inasmuch as there occurs a gradual transition from the hydrocarbons
to the sugars. In accord with this, the glycols have a sweetish taste,
are very easily soluble in water, slightly soluble in ether, and boil
much higher (about ioo°) than the corresponding monohydric
alcohols.

The hydrogen of the hydroxyls may be replaced by the alkali
metals (with formation of metallic glycollates, p. 126), and by acid
and alcohol radicals. The acid esters are produced by the action
of the salts of the fatty acids upon haloid compounds of the alky-
lens, or even when the free acids act on the glycols (p. 250) ; —

C.H,/g}|[ i- C,H30.0H = C.H./g^^H'O + H,0,
C.H,/gg +2C,H30.0H = C,H,/g;^^g30 ^ ^H.O.

The formation of acid esters is an excellent means of proving the number of
hydroxyl groups present in the polyvalent alcohols (the glycerols — sugars and the
phenols). The benzoic esters are especially easy of production by merely shaking
the substance under examination with benzene chloride and sodium hydroxide
(Berichte, 21, 2744; 22, Refs. 668 and 817). The nitric acid esters are also quite
well adapted to this purpose, and also the carbaminic esters, throtigh the action of
isocyanic acid esters (p. 273), more especially phenylisocyanic ester (see this).

The alcohol-ethers are obtained from the metallic glycollates by the action of
the alkyl iodides : —

C^H./gg' + C,H,I = C,H,(g-CzH5 + Nal,
C.H.<gS: + 2C,H,T = C,H,/g;g^H, ^ ^^^j

When the glycols are treated with hydrochloric and hydrobromic acid, the
primary and secondary /4a/«;(/ esters (p. 124) are produced. The former are also
called chlor- and brom-hydrins, while the latter represent the halogen compounds
of the alkylens : —

C.H.<gg + HCl = C,H,(g/^ + H,0,

Ethylene Chlorhydrin.

C,H^/gg + 2HCI = C,H,C1, + 2H,0.
Ethylene Chloride.

When heated with HI, a more extensive reaction occurs (p. 98).
The primary haloid esters can also be considered as substitution products of the
monohydric alcohols: —

C,H,/gf = CH,C1.CH,.0H.
Glycol Chlorhydrin. Chlor-ethyl Alcohol.

300 ORGANIC CHEMISTRY.

They, can be obtained, too, by the direct addition of hypochlorous acid to the
alkylens : —

CH^ CHXl

II + ClOH = I
CHj CHj.OH

Tlie hypochlorous acid is prepared by acting with chlorine upon HgO suspended
in water, or by saturating a dilute and cold solution of NaOH with the gas [Be-
richte, i8, 1767), or by the addition of aa excess of boric acid to a solution of
chloride of lime [Berichte, 18, 2287).

Nascent hydrogen converts them into monohydric alcohols: —

C2H4CI.OH + Hj = C2H5.OH + HCl.
When they are digested with salts they form primary esters: —
C.H,/°jj + C,H30.0K = C,H,/g-^^H30 ^ j^^I.

By treating the haloidhydrins with alkalies we obtain the anhy-
drides of the glycols or alkylen oxides : —

CHgCl CHgv

I + KOH =1 )0 + KCl + H^O.

CH„.OH CH/

Ethylene Oxide.

This is the only method of forming the a-alkylen oxides (those in which the
0-atoms are in union with adjacent C-atoms), whereas the y- and d-alkylen oxides
(those in which the second union occurs in the 7- or d-position with reference to
the first) can be obtained from the corresponding glycols by direct withdrawal ol
water when heated alone or upon boiling with 5°% sulphuric acid (Berichte, 18,
3285; 19, 2843). The a-glycols, under like treatment, yield either unsaturated
alcohols, aldehydes or pinacolines, depending upon their constitution (p. 310).

Such oxides, havirrg the oxygen attached to two carbon atoms,
are isomeric with the aldehydes and ketones, and boil at lower tem-
peratures than the latter. Notwithstanding they show neutral reac-
tion, they yet possess a strong basic character, precipitating metallic
hydroxides from solutions of metallic salts and uniting with acids
to form primary esters of the glycols : —

C,H,0-|-HCl = C,H,/g\j_
C,H,0 + C.H^O.OH = C^H.^g-j^^'^^aO

With the acid anhydrides they yield secondary esters of the
glycols : —

C,H,0 + (C,H30),0 = C,H,/g;C2H30

ETHYLENE GLYCOL. 30 1

The alkylen oxides are readily soluble in water (distinction from
alkyl oxides or esters). When the a-alkylen oxides are heated with
water the glycols are regenerated: This is not the case with the y-
and 5-glycols. It is also true that only the a-alkylen oxides form
hydramines with ammonia (p. 314). All alkylen oxides unite with
hydrochloric acid to form chlorhydrins.

Like the monohydric alcohols, the glycols also form sulphur com-
pounds, amines and sulphonic acids.

Methylene Derivatives.

Methylene Glycol, CH2(OH)2, is not known and cannot exist (p. 298).
Wherever it should occur it eliminates water and yields methylene oxide (i. e.,
formaldehyde), and trioxymethylene (p. 188). Its ethers and esters have been
prepared.

Methylene Diacetic Ester, CH2(O.C2H30)2, is produced on heating methyl-
ene iodide with silver acetate. An oily liquid, insoluble in water and boiling at
170°. Boiling alcohols saponify it, but instead of yielding the expected methylene
glycol, trioxymethylene is produced.

Methylene Dimethyl Ether, CHjfO.CHj)^, Methylalox Formal, is obtained
in the oxidation of methyl alcohol with MnOj and sulphuric acid. It is an ethereal
liquid of specific gravity 0.855, ^°<i ^^o-Ca at 42°. It is miscible with alcohol and
ether, and dissolves in 3 parts water. The diethyl ether, CH2(O.C2H5)2, is pre-
pared by the action of sodium ethylate upon methylene chloride, or iodide, and by
distilling trioxmethylene with alcohol and sulphuric acid. It boils at 89° (82°).
Its specific gravity is 0.8275 at 17°. Consult Berichte, 20, 553 for the higher
methylals.

I. Ethylene Glycol, QHeO^ = C^H^COH),.

This is a colorless, thick liquid, with a specific gravity of 1.125
at 0°, and boiling at 197.5°. It solidifies when exposed to low
temperatures, and melts at — 11.5°^ It is miscible with water and
alcohol. Ether dissolves but small quantities of it.

Preparation. — Heat a mixture of 195 grams ethylene bromide (l molecule),
102 grams potassium acetate (2 molecules) and 200 grams alcohol, of 90 per cent.,
until all the ethylene bromide is dissolved, then filter off the potassium bromide
and fractionate the filtrate {Demote). 2. Boil 188 grams ethylene bromide, 133
grams KjCO, and i litre of water, until all the ethylene bromide is dissolved
[Annalen, igz, 240 and 250).

On heating ethylene glycol with zinc chloride water is eliminated
and acetaldehyde (and crotonaldehyde) (p. 199) formed. Nitric
acid oxidizes glycol to glycollic and oxalic acids : —

CH,.OH CH^.OH CO.OH

I yields I and | .

tn,.OH CO.OH CO.OH

Glycol. Glycollic Acid. Oxalic Acid.

302 ORGANIC CHEMISTRY.

The following aldehyde-compounds are produced at the same
time : —

CHO CHO

I and I

CHO CO.OH.

Glyoxal. Glyoxylic Acid.

And when glycol is heated, together with caustic potash, to 250°,
it is oxidized to oxalic acid with evolution of hydrogen.

Heated to 200° with concentrated -hydrochloric acid, glycol is
converted into ethylene chloride, C2H4CI2.

Metallic sodium dissolves in glycol, forming sodium mono-ethylenate
C2H4/™ , and (at 170°) disodium ethylenate, C2H4(ONa)2. Both are white,
crystalline bodies, regenerating glycols with water. The alkylogens convert them
into ethers. /OH

Ethylene Ethyl Ether, C^H^- „ „ „ , is formed by the union of ethylene

oxide with ethyl alcohol. A pleasantly smelling liquid, boiling at 127°.

Ethylene Diethyl Ether, C2H^(O.C2H5)2, is insoluble in water, and boils
at 123°.

The following acid esters have been made : —

Glycol Mono-acetate, CjH^/q^^ "O^ boils at 182°, and is miscible with

water.

If hydrochloric acid gas be conducted into the warmed solution, glycol chlor-

acetin, C2'H.^(^'^^^^^^^,or chlorinated acetic ethyl ester, CH2Cl.CH2!o.

CjHjO, is produced. This boils at 144°.

Glycol Diacetate, C2H^(O.C2H30)2,is obtained by heating ethylene bromide
with silver acetate. A liquid of specific gravity 1. 128 at 0°, and boiling at 186°.
It is soluble in 7 parts water.

Glycol or Ethylene Chlorhydrin, CH2.Cl.CH2.0H(p. 299), is formed by
heating glycol to 160°, and conducting HCl through it, or by the addition of ClOH
to CjH^. It is a liquid, boiling at 128°, and is miscible with water. A chromic
acid mixture oxidizes it to monochlor-acetic acid, CH2CI.CO2H. Ethylene
bromhydrin, C2H4Br.OH, is not very soluble in water, and boils at 147°; its
specific gravity at 0° equals 1.66. When chlorhydrin is heated with potassium
iodide we get glycol iodhydrin, CjH^I.OH. This is a thick liquid, which de-
composes when distilled. /nw

Glycol or Ethylene- hydroxy-sulphuric Acid, CjH^/^^ „„ ^-.tt, is pro-
duced on heating glycol with sulphuric acid. It is perfectly similar to ethyl sul-
phuric acid (p. 150), and decomposes, when boiled with water or alkalies, into
glycol and sulphuric acid.

Ethylene Nitrate, C2H4(O.N02)2, is produced on heating ethylene iodide
with silver nitrate in alcoholic solution, or by dissolving glycol in a mixture of
concentrated sulphuric and nitric acids : —

C2H4(OH)2 + 2NO2.OH = C2H^(O.N02)2 + 2H2O.

TAis reaction is characteristic of all hydroxyl compounds [the folyhydric alco-
hols and polyhydric acids) ; the hydrogen of hydroxyl is replaced by the NO^
group.

ETHYLENE OXIDE.

303

The nitrate is a yellowish liquid, insoluble in water, and has a specific gravity
of 1.483 at 8°. It explodes when heated (like the so-called nitroglycerol). The
alkalies saponify the esters with formation of nitric acid and glycol.

Ethylene Cyanide, C2H4(CN)2, is obtained on heating an alcoholic solution
of ethylene bromide and potassium cyanide, and in the electrolysis of cyanacetic
acid. It forms a crystalUne mass, fusing at 54.5°. Boiled with acids or alkalies,
it passes into succinic acid, hence may be looked upon as the nitrile of the latter.
Nascent hydrogen converts it into butylene diamine, C.tH8(NH2)3.

• CH2

Ethylene Oxide, QH^O = | ;0, is isomeric with acetal-

ch/

dehyde, and is produced on distilling ethylene chlorhydrin or
ethylene chloracetin with caustic potash. A mobile, pleasantly
smelling, ethereal liquid, which boils at 13.5°, and at 0° has a
specific gravity equal to 0.898. It is miscible with water, gradually
combining with it to form ethylene glycol.

It unites with the acids to form chlorhydrins and glycol esters.
It also precipitates metallic hydroxides from solutions of metallic
salts (p. 300).

It combines with bromine, forming a crystalline, red bromide, (C^H^O^gBr,
which melts at 65°, and distils at 95°. Mercury changes the bromide to diethylene

CHj— O— CHj
ffXzV?, (CjH^O)^ = I I . This melts at 9°, and distils at 102°. It

CH2— O— CH2

combines with acetaldehyde to form ethylene-ethylidene ether, C^H^^^^ CH.
CH3, which boils at 82.5°.

Ethylene Thiohydrate, CjH^^^'ctt, glycol mercaptan, is formed on heating

an alcoholic solution of potassium sulphydrate with ethylene bromide [jBerichte, ig,
3263 and 20, 461). The odor of this compound is something like that of mercap-
tan. It boils at 146°; its specific gravity is I.I2. Insoluble in water, it dissolves
in alcohol and ether. Acids reprecipitate it from alkaline solutions. It throws out
mercaptides, e.g., CjH^.SjPb, from the salts of the heavy metals. It yields mer-
captals with aldehydes (p. 306). Sodium ethylate and alkyl iodides convert it into
dithio-ether, C2H^(S.R}2; the stronger organic acids change it to a dithio-ester,
e,g.,C^n^{%.C^nfi)^.

The monothiohydrate, CgH^^'^Qtr, is obtained when ethylene chlorhydrin

acts on potassium sulphydrate. It yields mercaptides with 1 equivalent of the
metals.

Ethylene Sulphide, C^H^S — isomeric with thioaldehyde, CH,.CHS, — is
formed on heating ethylene bromide with alcoholic sodium sulphide. It is
only known in its polymeric forms. At first a polymeric ethylene sulphide,
(C2H^S)n , is formed. This is a white, amorphous powder, insoluble in the ordi-
nary solvents. It melts at 145°, but is not very volatile. Protracted boiling with

phenol, changes it to diethylene disulphide, CjH^^g J)C2H^. It is analogous to

304 ORGANIC CHEMISTRY.

thiophene, and contains a closed chain of six members (Annalen, 240, 303). It is
similar to naphthalene. It melts at iio°, and boils at 200°. Diethylene sulphide
may be synthetically prepared from ethylene mercaptan, C2H4(SH)2, by the action
of sodium ethylate upon ethylene bromide, and this procedure will also yield the poly-
meric derivative, if it is desired [Berickte, 19, 3263). Another polymeric ethylene
sulphide (C^H^Sjn (this does not break up) is obtained from ethylene bromide
on boiling with aqueous potassium sulphide. It is very similar to the first, but is
not decomposed on boiling with phenol. Bromine and diethylene disulphide yield

CHg.S.CHg
Methyl Sulphurane, | , is produced on distilling this iodide with

sodium hydroxide. The closed ring of diethylene disulphide is broken.

The union of the derivatives of diethylene disulphide with the higher alkyl
iodides yields homologous compounds known as sulphuranes. They are the
alkyl vinyl ethers of thioethylene. Ethyl sulphurane or ethylvinyl ether has beea
synthetically prepared from glycolchlorhydrin {Berichte, 20, 1 830 ; Annalen, 240,

305)-

The mercaptals are closely related to diethylene disulphide. This is especially
true of ethidine dithioethylene, in which there is a closed ring of five members.

Diethylene Tetrasulphide, C^H^;' ^^ ^CjH^, is produced by the action of

the halogens upon ethylene thiohydrate (or sulphuryl chloride or hydroxylamine,
(p. 141). It is a white, amorphous powder, melting about 150° (^Berickte, 21, 1470).

Polyethylene Glycols or Alcohols.

The glycols, like the other dihydroxyl compounds (see disulphuric acid), can
condense to polyglycols by the coalescence of several molecules, water sepa-
rating at the same time. These condensed forms arise by the direct union of the
glycols with alkylen oxides, especially when heat of 100° is applied : —

,OH
C H '
CjH40 + C2H.(OH)„= " *\o Diethylene glycol.

r H '

,crH

2C2H4O + CjH /°g = CjH / Triethylene glycol.

\OH,

&c.

The polyglycols are thick liquids, with high boiling points. They behave like
the glycols. Anhydro-acids may be obtained from them by oxidation with dilute
nitric acid ; thus diglycoUic acid (see this) is formed from diethylene alcohol.

Diethylene Glycol, (C2H^)20(OH)2, boils at 250°. Triethylene Glycol,
(C2Hi)302(OH)2, boils at 285-290°. Tetraethylene Glycol boils above 300"".

ETHIDENE-DIETHYL ETHER. 305

Ethidene or Ethylidene Compounds.

Ethidene Oxide, CH3.CHO, is ordinary acetaldehyde. On mixing with water
heat is evolved, and we may suppose that, perhaps at the time, ethidene dihydrate,
CHs.CH(OH)2, is produced (p. 297). The ether derivatives, the acetals, on the
contrary, are very stable.

The alcohol ethers of ethylidene are formed in the oxidation of alcohols, whereby
aldehydes are first produced, and in turn combine with two molecules of the alco-
hols to yield acetals (p. 300). Hydrochloric acid acting on a mixture of an alde-
hyde and an alcohol, also produces them, chlorhydrins, however, being the first
products : —

CH3.CHO + C2H5OH + HCl = QYiyZYi.(^^^^ -f HjO,

and from these, through the action of sodium alcoholates, mixed acetals, e.g., me-
thyl butyl acetal, can be obtained [Berichte, 19, 3007 ; see, however, Berichte, 17,
Ref. 464). On heating the acetals with alcohols, the higher alkyls are displaced
by the lower alkyls (Annalen, 218, 44). On shaking or digesting the acetals with
hydrochloric acid, they are readily resolved into their components and reduce an
ammoniacal silver solution with the production of a silver mirror.
The acid chlorides form chlorhydrins : —

CH3.CHO + CjHsOCl = CH3.CH(^°-^2^^3°,

from which mixed acid acetals can be made by the action of organic silver salts
{Berichte, 17, 473).

/O cw
Ethidene-dimethyl Ether, CH3.CH<' q'^S', Dimethyl Acetal, occurs in

crude wood-spirit, and is produced in the oxidation of a mixture of methyl and
ethyl alcohols; also upon heating acetaldehyde with metliyl alcohol. An ethereal
liquid, boiling at 64°; its specific gravity, equals 0.867 at l°-

Ethidene-methyl-ethyl Ether, CHj.CH^' ^'^^ ^ is produced together with

the dimethyl ether in the oxidation of wood-spirit and alcohol. It boils at 80-85°.
It is a mixture of dimethyl and diethyl acetal-(see above).

Ethidene-diethyl Ether, CH3.CH('q„2 6, Acetal, occurs in the course

of the distillation of crude spirit and is produced: —

1. By oxidizing alcohol with MnOj and sulphuric acid.

2. By heating alcohol and acetaldehyde to 100°.

3. By the action of sodium ethylate upon ethidene bromide and monochlor-

ether.

Acetal is sparingly soluble in water, has an odor somewhat like that of alcohol,
and boils at 104°; at 20° its specific gravity equals 0.8314, It is rather stable in
presence of alkalies; dilute acids, however, easily convert it into aldehyde and
alcohol {Berichte, 16, 512). Chlorine produces substitution products; mono-,
di-, and tri-chloracetal, CCl3.CH.(O.C2H5)j. Sulphuric acid breaks these up into
alcohol and aldehyde (p. 19S). Monochlor-acetal, C'H.^.CC\{O.C^'iiX, }^ most
readily obtained by boiling the dichlor-ether with absolute alcohol {Berichte 21,
617). It boils at 157°. When heated with alcoholic ammonia, it passes into ace-
talamine, C)i^.C{^Yi.^{O.Cfi.^.„ an alkaline liquid, boiling at 163°- It yields
condensation products quite readily (j5^>-2Vy4/.?, 21, 1482; 22, 568).

Acid esters of ethidene may be prepared by heating ethidene chloride with salts
26

306 ORGANIC CHEMISTRY.

of the fatty acids, and by the union of aldehyde with acids, acid chlorides, and acid
anhydrides (p. 248).

Acid chlorides convert ethidene into chlorhydrin : —

CH3.CHO + C2H3OCI = CHs.Ch/^j^^^sO.

Mixed acid acetals are obtained from the latter by the action of organic silver
salts [Berkhte, 17, Ref. 473).

Ethidene Chloracetate, CHg.CH/^^j*"'!^^*-*, chlorinated acetic ethyl ester,

boils at 121.5°, 3"<J 's gradually decomposed by v\rater into aldehyde, acetic acid
and HCl.

Ethidene Diacetate, CH3.CH<^q^2H30^ j^ ^^^ ^^ soluble in water,
boils at 188.4°, ^nd is split into aldehyde and acetic acid when boiled with water.

Ethidene Acetpropinate, CHj.Ch/qS^^^O boiling at 178.6°, is identi-
cal with ethidene propio- acetate (see above). This is a further proof of the equi-
valence of the carbon affinities {Annalen, 225, 267).

Aldehyde ammonia, CHo.CH^ pitt ^, and aldehyde hydrocyanide (oxycyanide),
/CN \UH

CHj.CH^ ^TT (p. 190), are also ethidene compounds.

SULPHUR COMPOUNDS.

The thio-acetals are perfectly similar to the acetals. They have been called
mercaptals and mercaptols. Mercaptals are formed from mercaptans and aldehydes
by the interaction of HCl:— CH,.CHO + 2C,H5SH = CHj.Ch/^-^^Hs

+ HjO. The mercaptols are obtained in the same manner from the ketones, e.g.,
(CHjjjCO. These thio-acetals are insoluble in water and generally liquid com-
pounds. They are quite stable and are not changed by boiling with alkalies or
acids [Berichti, 18, 883; ig, 2803). Analogous compounds are obtained with
the ketonic acids (Berichte, 19, 1787).

Instead of using the mercaptans for the preparation of the mercaptols, employ
the alkyl-thiosulphates. Hydrochloric acid decomposes these into primary sul-
phates and mercaptans, and the latter, in the presence of acetones, immediately
yield the mercaptols (^Berichte, 22, Ref. 115).

Methylene Mercaptal, CH2(J5.C2H5)2, has been obtained from methylene
iodide by the action of sodium ethyl mercaptide. It is an oil, boiling at 180°.

Ethidene Dithioethyl, CH3.CH(S.C2H5)2, dithioacetal, the ethyl mercaptal
of acetaldehyde, is a very mobile liquid, with an odor like that of thioaldehyde.
It is lighter than water and boils at 186°.

Acetone Dithioethyl, (CH3)2C(S.C2H5)2, the ethyl mercaptal of acetone,
boils at 190° {Berichte, 19, 1787 ; 22, 2595). Permanganate of potassium oxidizes
it to sulphonal.

Propidene-dithio ethyl, C2H5.CH(S.C2H5)2, from propionic aldehyde and
ethyl mercaptan, boils about 198°.

CH^.S,

Ethylene Mercaptals, ^. ^., | ;CH.CH,, and Ethylene Mercaptols,

CH,.S/

DISULPHONES. 307

are similarly produced by the action of ethylene mercaptan upon aldehydes and
ketones {Berichte, 21, 1473) : —

HS.CHj .S.CH^

CH3.CHO + I = CHj.CHf I + H.O.

HS.CH2 \S.CH2

They contain a nucleus of five members. It is somewhat less stable than the
nucleus of diethylene disulphide, containing six members (p. 304).

Ethylene-dithio-ethidene, CjH^SjiCH.CHj. An oil boiling at 173°.

DISULPHONES.

These are produced in oxidizing the dithio-ethers or thioacetals with a perman-
ganate solution. Each sulphur atom takes up two oxygen atoms : —

Dithio-ethyl-ethidene. Ethidene-diethyl Sulphone.

Mercaptals yield disulphones of the type RCHfSOj.CjHj)^, and the mercap-
tols those of the form RjC^SOj.CjHjjj. Athird class of disulphones is kiiown:
0112(802.02115)2, obtained by oxidizing ortho-thio-formic ester, CH(S.C2H6)3.

In the disulphones of the first and third classes the hydrogen of the groups CH 2
and CRH can be easily replaced by the halogens, and by the alkali metals [Be-
richte, 21, 652). This is similar to the substitutions in aceto-acetic ester and
malonic ester. The alkali metals which enter can be further replaced by alkyls
{Berichte, 21, 185 ; 22, Ref 678) :—

CH3.CH(S02.C2H5)2 yields ^^C{%O^.C^n,\.
Ethidene-diethyl Sulphone, Acetone-diethyl Sulphone.

These disulphones are solid, crystalline and very stable compounds. Acids and
alkalies do not attack them.

Methylene-diethylsulphone, CH2(S02-C2H5)2, is formed by the oxidation
of trithioformic ester and methylene mercaptal. It crystallizes in needles, melting
at 104°. It is very soluble in alcohol and water.

Ethidene-diethylsulphone, CH3.CH(S02.C2H5)2, from ethidene mercaptal,
has also been prepared from a-dithio-ethylpropionic acid. It melts at 75° and
boils at 320° without decomposition.

Acetone-diethylsulphone, (CH.,)2C(S02.C2H5)2, Sulphonal, is made by
oxidizing acetone-ethylmercaptol with permanganate. It also results from the
action of sodium hydroxide and methyl iodide [Annalen, 253, 147) upon ethidene-
diethylsulphone. It dissolves in 100 parts water at 16°, in 20 parts at 100°, and
readily in alcohol.

It crystallizes in colorless leaflets or plates, melting at 126°. It is odorless and
tasteless. In doses of 0.5-3 S?- '' "^ "^ed as a hypnotic.

Consult Berichte, 22, 678 and 829 for additional sulphones.
CHj.SOjR CH2.SO2

Ethylene Disulphones, I and I >CH.R, result from the oxi-

CH2.SO2.R CH2.SO2
dation of ethylene 'dithio-ethers, C2H4(S.C2H5)2 (p. 303), and ethylene-mer-
captals and mercaptols (p. 306). These sulphones are saponified and decomposed
on boiling with alkalies {Berichte, 21, 1474}.

308 ORGANIC CHEMISTRY.

CHg.SOg.CgHg
Ethylene-diethylsulphone, | , has been obtained from ethylene

CH2.S02'C2Hg
bromide by the adtion of 2 molecules of sodium ethyl sulphinate, and from sodium
ethylene disulphinate (p. 303) by the action of 2 molecules of ethyl bromide. The
hexavalence of sulphur in the sulphones is thus proved (see p. 144 and Berichte,
21, Ref. 102). It yields colorle'ss needles, melting at 137°.

Diethylene Disulphone, C^H^/lQ^^CaHi, results from the oxidation of

diethylenedisulphide (p. 303), and ethylene disulphinate of sodium with ethylene
bromide.

Trimethylene trisulphone (p. 193), trialdehyde trisulphones (p. 197), and tri-
acetone trisulphone (p. 205) are examples of trisulphones.

2. Propylene Glycols, CaHgO^ = CsHeCOH)^.
The two glycols theoretically possible are known : —

CH3.CH(OH).CH2.0H and CH2(OH).CH2.CH,.OH.

o-Propylene Glycol. p-Propylene Glycol.

a-Propylene Glycol is obtained by heating propylene bromide
with silver acetate and saponifying the acetic ester first produced
with caustic potash. Propylene chloride heated with water and
lead oxide also yields it. It is most readily prepared by distilling
glycerol with sodium hydroxide {Berichte,'!.^, 1805). It is a thick
liquid, with sweetish taste. It boils at 188°. At 0° its specific
gravity equals 1.051. Platinum black oxidizes it to ordinary lactic
acid. Only acetic acid is formed when chromic acid is the oxidiz-
ing agent. Concentrated hydriodic acid changes it to isopropyl
alcohol and its iodide.

When exposed to the action of the ferment Bacterium termo, ordinary pro-
pylene glycol becomes optically active and yields an active propylene oxide
{Berichte, 14, 843).

Propylene Diacetate,Z^^^(p.C^fi')^,h<yA?, at 186°; specific gravity 1. 109
ato°. The a-chlorhydrin, CH3.CH(OH).CH2Cl, is produced when sulphuric
acid and water act upon allyl chloride. It boils at 127° and is oxidized to
mono-chloracetic acid by nitric acid. ^-Chlorhydrin, CHg.CHCl.CHj.OH, is
produced by adding ClOH to propylene. This also boils at 127°, but on oxida-
tion yields a-chlorpropionic acid, CH3.CHCI.CO.OH. a- Propylene Oxide,

Y-TT /O, from the chlorhydrins, boils at 35°, is readily soluble in water, and

yields isopropyl alcohol, CH3.CH(OH).CH3, with nascent hydrogen.

i3- Propylene Glycol, CH5,(OH).CH2.CH2(OH), trimethylene
glycol, is formed by boiling trimethylene bromide with a large
quantity of water or potassium carbonate {Berichte, 16, 393). Its
■formation from glycerol in the schizomycetes-fermentation is worthy

BUTYLENE GLYCOL. 309

of note. It is a thick liquid, miscible with water and alcohol, boil-
ing at zi6°, and having a specific gravity at o° of 1.065. Hydro-
bromic acid changes it to bromhydrin, which yields ^'-oxybutyria
acid with potassium cyanide. Moderately oxidized it forms /S-oxy-
propionic acid.

Its diacetaie, CH2(CH2. 0.031130)2, boils at 210°; its specific gravity at 19° is
1.07. Tliechlorhydrin,CH^Cl.CH2.CH2.0H,is obtained by conducting HOI into
glycol. It boils at 160°, and its specific gravity at 0° is 1.146. It is soluble in
2 volumes of water, and, virhen oxidized with chromic acid, becomes j3-chlorpro-
pionic acid. Trimethylene oxide, CHjcf ^tt* ^O, is prepared by heating chlor-

hydrin with caustic potash. A mobile liquid, with penetrating odor, and boiling
at 50°. It mixes readily with water and condenses without difficulty.

3. Butylene Glycols, QHioO., = QHsCOH),.

Four of the six possible butylene glycols (p. 298) are known.

(i) a-Eutylene Glycol, CH3.CH2.CH(OH).OH2.0H,is obtained from a-buty-
lene bromide; boils at 191-192°, and at 0° has a specific gravity of 1.0189. Nitric
acid oxidizes it to glycoUic and glyoxylic acids.

(2) /9-Butylene Glycol,CH3.CH(OH).CH2.CH3.0H, is formed
in slight quantity, together with ethyl alcohol, in the action of
sodium amalgam upon aqueous acetaldehyde (p. 193). Aldol very
probably appears as an intermediate product in this reaction, and
from it the glycol can be directly made by the use of sodium amal-
gam {Berichte, 16, 2505) : —

CH3.0H(0H).CHj.CH0 + H^ = CH3.CH(OH).CH2.CH2.0H.

/3-Butylene glycol is a thick liquid, which boils at 207°, and
mixes with both water and alcohol. When oxidized by either nitric
or chromic acid it forms acetic and oxalic acids (along with some
crotonaldehyde) .
" Aldol is the aldehyde of butylene glycol.

(3) 7-Butylene Glycol, OH3.CH(OH).CH(OH).CH3, is formed from /3-buty-
lene bromide. It boils at 183-184°- Its specific gravity at 0° equals i .048. Nitric
acid oxidizes it to oxalic acid.

(4) Isobutylene Glycol, (CH3)2.C(OH).CH2.0H, is obtained from isobuty-
lene bromide. It boils at 176-178°. At 0° its specific gravity is 1.0129. Nitric
acid converts it into a-oxyisobutyric acid.

Its chlorhydrin, (CH3)2.CCl.CH2.0H,is produced by adding ClOH to isobuty-
lene. It boils at 128-130°, and when oxidized becomes chlor-isobutyric acid.

(5) Tetramethylene Glycol, CH2(OH).(CHj)2.0H2.0H, has been obtained
from tetramethylene-diamine (p. 313). Its dibromide boils at 190°.

4. Amylene Glycols, C.HijOj = O.Hjj(OH)2.

(I) /3-Ainylene Glycol, CH3.CH.,.CH(OH).CH(OH).CH3, is derived from-

310 ORGANIC CHEMISTRY.

;3-amylene bromide (p. 84). It boils at 187°. Its specific gravity at 0° is 0.994.
By oxidation it yields a-oxybutyric acid and acetic acid.

(2) a-Isoamylene Glycol, (CH3)2CH.CH(OH).CH2(OH), from a-isoamy-
lene bromide, boils at 206°- Its specific gravity at 0° is 0.998. When oxidized
it yields oxy-isovaleric acid.

(3) /J.Jsoamylene Glycol, (CH3)2C(OH).CH{OH).CH3, from /3-isoamylene
bromide, boils at 177°- Its specific gravity at 0° is 0.967. When oxidized it
yields a-oxy-isobutyric acid.

(4) y-Pentylene Glycol, CH3.CH(OH).CHj.CH2.CH2.0H, is formed from
aceto-propyl alcohol, CHj.CO.CH^.CHj.CHj.OH (p. 322), by the action of sodium
amalgam. A thick oil, very soluble in water, and boiling at 219°. At this tem-
perature it partly decomposes into water and 7-pentylene oxide, C.Hj„0, boiling
about 80°. The latter product is tetrahydromethylfurfurane, CjHjO {Berichle,
22, 2567).

/PT-T PM OT-T

(5) Pentamethylene Glycol, CH^^' CH^ Ch'' OH ' °'^'*'°^'l ^7 ^^ action

of silver nitrite upon pentamethylene-diamine hydrochloride (p. 313), boils at 260°.

5. Hexylene Glycols, CjHijOj.

(i) Hexylene Glycol, CgHj2(OH)2, from hexylene bromide, boils at 207°.
Its specific gravity at 0° is 0.967.

(2) Diallyl Hydrate, C^i^{0^\, is obtained from diallyl, (€3115)2 (p. 89), by
means of the Hl-compound, C^^^^. It boils at 212-215°.

(3) <5-HexyIene Glycol, CH3.CH(OH).(CH2)3.CH20H, is obtained from
aceto-butyl alcohol, CH3.CO.CjHg.OH (p. 322), by the action of sodium amalgam.
It boils near 235° (under 710 mm. pressure) and speedily passes into S-hexylene
oxide, CgHijO, boiling at 105° C. (p. 300).

(4) Tetramethyl-ethylene Glycol, (CH3)2.C(OH).C(OH.(CH3)2, or Pina-
cone, is formed, together with isopropyl alcohol, when soOium amalgam or sodium
acts upon aqueous acetone (p. 203}.

CgAcO + Cq/CHs ^ h, = ^g^>C(OH) - .C(0H)/CH3 . .

it can be obtained, too, from the bromide of tetramethyl-ethylene (from dimethyl-
isopropyl-carbinol). It crystallizes from its aqueous solution in the form of the
hydrate, CgH^Oj -f- 6H2O, which consists of large quadratic plates, melting at
42°, and gradually efflorescing on exposure. In the anhydrous state it is a crys-
talline mass which melts at 38° and boils at 171-172°-

When heated with dilute sulphuric or hydrochloric acid pinacone parts with i
molecule of water, and by molecular transposition, becomes pinacoline, CjHjjO
(p. 203).

Dimethyl-pinacone is the representative of a series of similarly constituted
glycols — the pinacones. These contain two hydroxyl groups attached to two
adjoining carbon atoms, which in turn are linked to two alkyls. All the pinacones
show similar deportment, in that when they are heated with acids they part with
water and suffer molecular transposition into ketones — the pinacolines (p. 202) —
see also benzpinacone.

Another pinacone of the fatty series is : —

Methyl-ethyl Pinacone, J^^3\c(OH).C(OH)/^^ . This is obtained
from p tt' yQO. It is a crystalline mass, melting at 28°, and boiling at 200-

AMINES OF THE DIVALENT RADICALS. 3IT

205°. It does not form a hydrate with water. When heated with sulphuric acid
(diluted with i part water) it yields pinacoline by a transposition of the methyl
group :—

CH3\

CH3— C— CO— CjHj, Ethyl-tertiary-amyl-ketone.
CM,/

This is a liquid with an odor like that of camphor, and boils at 145-150°. When
oxidized with chromic acid it decomposes into acetic acid and dimethylethyl acetic

acid, ("^i^s)2%c.COjH.

The higher glycols have received very little attention.

AMINES OF THE DIVALENT RADICALS.

The di-, like the mono-valent alkyls, can replace two hydrogen atoms in two
ammonia molecules and produce primary, secondary, and tertiary diamines. These
are di-acid bases, and are capable of forming salts by direct union with two"
equivalents of acids. They are prepared by heating the alkylen bromides with
alcoholic ammonia to 100° (p. 157) in sealed tubes: —

C,H,Br, + 2NH3 = C,H /?JJ!^2HBr,

Ethylene Bromide. ^^ ,^ i?.2 •

Ethylene Diamine.

2CH,Br„ + 4NH3 = N— C.H,— N.aHBr + 2NH4Br,
\NH/

Diethylene Diamine.

SCoH.Br. + 6NH3 = N— QHj— N.2HBr + 4NH4Br.
\C,H,/
Triethylene Diamine.

To liberate the diamines, the mixture of their HBr-salts is distilled with KOH
and the product thfn fractionated.

Another very convenient method for the preparation of diamines is the reduction
of alkylen dicyanides (p. 313) with metallic sodium and absolute alcohol (see
p. 159 and Berichte, 20, 2215) : —

CH..CN

1 + 4H, = I

CHj.CN CH,.CH2.NH2

Ethylene Cyanide. Tetramethylene Diamine.

In the primary and secondary diamines the amid-hydrogen (by action of alkyl
iodides) can.be further substituted by alkyls, whereas the tertiary diamines unite
with the alkyl iodides to ammonium iodides.

Further, the diamines unite directly with water, forming ammonium oxides: —

P „ /NH^ , H O - C H /NHsNn

312 ORGANIC CHEMISTRY.

These compounds are very stable, and only lose water when distilled over KOH.
They part with water when acted upon with acids and yield diamine salts.

Acid derivatives result from the action of acid chlorides upon the
diamines. The formation of the dibenzoyl compounds, e. g.,
C2H4(NH.CO.C6H5)2, on shaking benzoyl chloride and sodium
hydroxide with the diamines, is employed for the detection of the
latter {Berichte, 21, 2744).

The separation of ammonia from the diamines gives rise to the
imines, which may be compared to the acid-imides. They also
appear together with the diamines in the reduction of the alkylen
cyanides (see above), and are directly, obtained from the diamines
upon heating their HCl-salts {Berichte, 18, 2956) : — .

CHj.CH^.NHj CHj.CHj.
I = I )NH + NH3.

These imines are identical with the tetrahydro-compounds of the
pyrrol and pyridine bases.

Of the many diamine derivatives formed by these methods, we may cite the
following : —

Ethylene Diamine, C^/-^^, is a colorless liquid, boiling at 123°. It

reacts strongly alkaline, and has an ammoniacal odor. It is also produced when
nascent hydrogen (tin and HCl) acts upon dicyanogen (p. 265) : —

CN CH,.NH,

1
CN

+ 4H, = I
CI

Nitrous acid converts it into ethylene oxide, ethylene glycol being very probably
first formed (p. 161) : —

CH2.NH2 CHj.

I + N,03 =1 )0 + 2H,0 + 2N,.

CH^.NHj CH/

Ethylene diamine, like the ortho-diamines of the benzene series, combines with
ortho-diketones, e.g., phenanthraquinone and benzil, to form tetrahydropyrazin-
derivatives {Berichte, ao, 267). It also unites with the benzaldehydes and benzo-
ketones [Berichte, 20, 276; 21, 2358).

Diace'tyl-diethylene Diamine, C2H^(NH.C2H30)2, is produced by the ac-
tion of acetic anhydride upon ethylene diamine. It consists of colorless needles,
melting at 172°. When this compound is heated beyond its melting point, water
splits off, and there follows an inner condensation that leads to the formation of an
amidine base (p. 293) {Berichte, 21, 2332) : —

CHj.NH.CO.CH, CH,.NH

I =1
CH2.NH.CO.CH3 CH^.N;
Diacetyl-diethylene Ethylene-ethenyl

Diamine. Amidine.

\C.CH3 + CH3.CO2H.

PENTAMETHYLENIMINE. 313

The derivatives of other acids, as well as the propylene diamine and trimethylene
derivatives, react similarly. These amidine bases are intimately related to the gly-
oxalines.

Ethylene-ethenyl Amidine, CjHjiNjHiqHj.or Ethylene acetamidine, is a
white crystalline mass very readily soluble in water. It melts at 88°, and boils
about 223°. »

On heating its HCl-salt, a molecule of NH, escapes fronr ethylene diamine, and

there results ethylene imine, \ ^NH (see above), which is apparently identical

CH/
with the base spermine, CjHjN (Berichte, 20, 444).

Di-ethylene Diamine, CjH^Q /C^Hj =1 I , containing a

^NH/ CHj.NH.CHj

chain of six members, is to be regarded as hexahydro-pyrazine (piperazine). It is
formed in the action of ethylene bromide on ethylene diamine. It is a liquid, boil-
ing at 172° {Berichte, 20, 444).

CHj.CH.NHj
Propylene Diamine, | , from propylene bromide and alcoholic

CH,.NH,
ammonia, is a liquid, boiling at li7°-i2o°. Its diacetyl derivative yields an ami-
dine base when heated. /rw tctt
Trimethylene Diamine,CH2<f^g2-^g2^ from trimethylene bromide, boils at

I3S°-I36°- By the action of trimethylene bromide upon potassium phthalimide,
a derivative of y-brompropylamine, CHjBr.CIIj.CHj.NHj, is produced. This loses

water, and apparently yields trimethylene-imine, CHj/^p^^Xnh (Berichte, 21,

^^78)- CH,CH,Ni<

Tetramethylene Diamine, C4Hj(NH2)2 = | , is obtained from

CH2.CH2.NHj
ethylene cyanide by the action of nascent hydrogen (see above), and by the action
of hydroxylamine upon pyrrol, C^H^NH, accompanied by further reduction {Be-
richte, 22, 1968). It is identical with the putrescine {Berichte, 21, 2938), which
has been isolated from decaying matter. It is a liquid with a peculiar odor. It
fumes in the air, and boils at i56°-t6o° It solidifies on cooling to a crystalline
mass, melting at 24°. There is always present with the diamine a slight quantity
of teiramethy/en-imine' C^Hg-.NH. (see above), which can be directly obtained by
heating the HCl-salt of the diamine. It is identical with pyrrolidine or tetrahydro-

Pyrol- /CH CH NH

Pentamethylene Diamine, C5Hi„(NH2)2 = CH/ ch" CH^ Nh''' o^t^i^ed

by the reduction of trimethylene cyanide, C3H8(CN)2, is a thick liquid, with an
odor resembling that of piperidine. It boils at I78°-I79°, and solidifies in the
cold. Its specific gravity at 0° is 0.9174 {Berichte, 18, 2956; ig, 780). It is
identical with cadaverine (p. 316), a ptomaine isolated from decaying corpses {Be-
richte, 20, 2216 and Ref. 69).

Neuridine, CjHi^Nj {Berichte, 18, 86), formed by the decay of fish and meat,
is isomeric with pentamethylene diamine. /cv\ CW v

Pentamethylenimine, C5HiiN=CH2<'^y=i'^H2\NH, from trimethylen-

cyanide, and also from its HCl-salt, is identical with piperidine-hexahydropyridine
{Berichte, 18, 2956). CHj.CH.CHj.NHj

fl-Methyl-tetramethylene Diamine, I , from pyrotartaric

CH2.CH2.NH2
acid nitrile, CH3.C2H3(CN)2, boils at I72°-I73°, and by splitting off NH3, yields

314 ORGANIC CHEMISTRY.

CHg.CH.CHg V
/3-Methyl Pyrrolidine, | J) N, boiling at 103° (Berichte, 20, 1654).

CHj.CH/
CHj.CH(CH3)
a-Methyl Pyrrolidine, | >NH, is produced by the reduction oC

CH,.CH,^'
y-amido valeric acid. It boils at 97° (Berickte, 22, 1866).
CH2.CH(CH3).NH2
DiamidoHexane, I ,is formed in the reduction of the di-

CH2.CH(CH3).NH2
phenylhydrazone of acetonyl acetone. It boils at 175°. On splitting off NH^,
it becomes (i.4)-Dimethyl Pyrrolidine, boiling at 107° {Berichte, 22, 1859)/-

By permitting the tertiary monamines to act upon ethylene bromide we obtain
the bromides of ammonium bases ; —

rrH^N-l-rHRr ('-'2^5)3 \ ^

I'-a^shJ-^ + <-2"4Jirj _ c^H^Br i N.Br.

The bromine attached to the nitrogen of these compounds can be readily re-
placed, whereas, the other bromine atom is more intimately combined. Silver
nitrate produces the nitrate of triethyt-bromethyl-ammonium : —

(?2J?5)3|n.O.N02

C,H,BrJ

And by the action of moist silver oxide, the bromine atom in union with carbon
is also attacked, HBr separates, and the group, CHjBr.CH^, is changed to the
vinyl group, CHjiCH. In this manner we get the triethyl-vinyl- ammonium base

(^2115)3 1 V
C2H3 TN.OH.

OXYETHYL BASES OR HYDRAMINES.

When ethylene oxide and aqueous ammonia act upon each other, i, 2 and 3
molecules of ethylene oxide unite with l molecule of ammonia, and form the
bases : —

CH2{OH).CH2.NH, Ethylene Hydramine.

CH2(0H).CH,\,,„

CH^^OHJ.CH^/^" Diethylene "

CHJ0H).CH2\

CHJOHJ.CH^— N Triethylene "

CH,(OH).CH,/

The HCl-salts of these bases are produced by the action of ethylene chlor-
hydrin, CH2CI.CH2.OH, upon ammonia. The bases are separated by fractional
crystallization of their HClsalts, or platinum double salts. They are thick,
strongly alkaline liquids, which decompose upon distillation.

OXYETHYL BASES OR HYDRAMINES. 315

The alkylen oxides and their chlorhydrins also combine with the amines. Such
oxyalkyl bases may be obtained from the allyl amines by addition of water (by the
action of H2SO4 (Berichte, 16, 532). The bases obtained from the secondary
amines are alkamines or alkines {Berichte, 15, 1 143) : —

(C,H5)2NH + CH.Cl.CH^.OH = (C^H J,N.CH,.CH,OH + HCl.

Triethyl Alkamine.

When digested with organic acids and hydrochloric acid, these oxyethyl bases
yield (by replacement of the hydrogen of OH by acid radicals) ester-like com-
pounds, termed Alkeines (see Tropeine).

Oxy-ethylamine, CH^OH.CHj NHj, amido-ethyl alcohol, is produced when
vinylamine is evaporated with nitric acid [Berichtg, 21, 2668).

Oxy-ethylmethylamine, CHjOH.CHj NH.CH3, results from ethylene chlor-
hydrin and methylamine when they are exposed to a temperature of iio°. It is a
liquid, boiling at 130-140°.

Oxy-ethyldimethylamine, CH20H.CH2.N(CH3)2, has been obtained in the
decomposition of morphine [Berichte, 22, ms). It boils at 128-130°.

Dioxy-ethylamine, cn'rom CH^/'^'^ = C^HuNOj, imido-ethyl alcohol,
is formed in the action of ammonia upon ethylene oxide and glycol chlorhydrin.

If this compound be heated to 160° with hydrochloric acid and distilled with
caustic potash it loses water, and yields an inner anhydride, C^HgNO : —

CH2(0H).CH.,/^" — "XCHj.CHj/^" + "2^-
Dioxy-ethylamine. Morpholine.

This contains a closed, six-membered nucleus, consisting of four C-atoms, one
O-atom, and one N-atom. It is the tetrahydro-derivative of Para-azoxine,
C4H5NO. It has been called morpholine, as it is very probable that an analogous
atomic grouping exists in morphine.

Alkylized morpholines, C^H8N(R)0 [Berichte, 22, 2081), are produced in an
analogous manner from the dioxy-ethyl alkylamines, [CHj(OH).CH2]2NR.

The bases obtained from the tertiary amines are especially interesting. Choline
is one of them. It is quite important physiologically.

Choline, C5H15NO2 = C^H^/g^jj^^^ qH^ oxyethyl-trimethyl

ammonium hydroxide. This was first discovered in the bile (henge
called choline or bilineurine). It is quite widely distributed in the
animal organism, especially in the brain, and in the yolk of egg, in
which it is present as lecithin, a compound of choline with glycero-
phosphoric acid and fatty acids. It is present in hops, hence occurs
in beer. It is obtained, too, from sinapin (the alkaloid of Sinapis
alba), when it is boiled with alkalies (hence the name sincalin).
Choline is artifically prepared by heating trimethylamine with
ethylene oxide in aqueous solution : —

(CH3)3N + qH.O + H2O = (CH3)3N/ggy^"-°"-

3l6 ORGANIC CHEMISTRY.

Its hydrochloride is produced by means of ethylene chlor-
hydrin : —

(CH3)3N + CH,Cl.CH,.OH = (CH,)3-N/^f ^'^^^^-^"^

Choline deliquesces in the air and crystallizes with difficulty. It
possesses a strong alkaline reaction and absorbs CO^. Its platinum
double salt, (C5Hi40NCl)2.PtCU, crystallizes in beautiful reddish-
yellow plates, insoluble in alcohol.

Isocholine, CH3.CH(OH).N(CHj)3.0H, isomeric with choline, is obtained by
introducing CH3 into aldehyde- ammonia (^Berichte, 16, 207). Muscarine, CjHj
(OH)2.N(CH3)3.0H, is an oxycholine. It is found in fly agaric, and is formed
by oxidizing choline with HNO3.

When choline is heated with hydriodic acid, we obtain the compound, (CHj),

j^ / 2- 2 -pjjjg jnoist silver oxide converts into vinyl-trimethyl-amnionium
hydroxide : —

(CH3)3N/gg=CH2 _ qHj3NO.

This base resembles choline ; it has also been obtained from the brain substance,
and bears the name Neurine. It is very poisonous. It is produced when cho-
line decomposes, or upon boiling it with baryta water. It occurs with the
ptomaines — alkaloids of decay, partly poisonous and partly non-toxic. This decom-
position is due to pathogenic bacteria, and the first product is choline, then neuri-
dine, CjHj^Nj (p. 313), and trimethylamine. Later, cadaverine, CjHjjNj,
identical with pentamethylene diamine (p. 313), putrescine, C^HjjNj, identical
with tetramethylendiamine, and saprine, CjHj^Nj, appear, and with them the toxic
oxygen bases mydatoxine, CjHj3N02, and mydine, CgHjjNO. Mytilotoxine,
C5H]5N02, has been prepared from a poisonous mussel. It is similar to curara
(see Brieger, Berichte, 20, Ref. 58, upon ptomaines).

Betai'ne (oxyneurine, lycine), C5H11NO2, is allied to choline.
It must be considered as trimethyl glycocoll (see this). It is
obtained by the careful oxidation of choline, when the primary
alcohol group, CHj.OH, is converted into CO. OH, and the ammo-
nium hydroxide that is first formed parts with a molecule of water
(see Amido-acids) : —

(CH3)3N/gg2CO-OH _ (cH3)3N/g'^° + H2O.

Trimethyl Glycocoll.

Its hydrochloride is obtained directly by synthesis, when tri-
methylamine is heated with monochloracetic acid : —

V .CH2.CO.OH
(CH3)3N -f CH2CI.CO.OH = (CH3)3N<;

^Cl

and on heating amidoacetic acid (glycocoll), NHj.CHj.COOH,
with methyl iodide, caustic potash and wood spirit.

SULPHONIC ACIDS OF THE DIVALENT RADICALS. 317

Betaine occurs already formed in the sugar-beet {Beta vulgaris),
hence, is present in the molasses from the beet. It crystallizes from
alcohol with one molecule of water in shining crystals, which deli-
quesce in the air, has an alkaline reaction and a sweetish taste. At
100° it loses one molecule of water. When boiled with alkalies it
decomposes, liberating trimethylamine.

PHOSPHORUS BASES.

A number of diphosphines are derived from phosphine ; they are perfectly
analogous to the diamines (p. 157).

When triethylphosphine acts upon ethylene bromide we obtain ; —

(C,H,)3P + C,H,Br, = (C,H,)3P/^J^^*^^

Triethyl-bromethyl-
phosphonium Bromide.

Br

(CjHj),?/
and zCC^H^),? + C^H.Br, = )C,H,

(C,H,)3P/

^Br.

Hexethyl-ethylene-diphosphortium

Bromide.

The phosphonium bases are set free by the action of silver nitrate or oxide upon
the preceding compounds.

Triethyl arsine, As(C2H5)3, forms similar derivatives with ethylene bromide.

SULPHONIC ACIDS OF THE DIVALENT RADICALS (p. 152).

Methene Disulphonic Acid, CH^^gQ^^, Methionic Acid, is obtained by

acting on acetamide or methyl cyanide with filming sulphuric acid. The acid
forms long, deliquescent needles. The barium salt, CH2(S03)2Ba + aH^O,
occurs in pearly leaflets, and is sparingly soluble in water. Barium chloride pre-
cipitates it from a solution of the acid. The free acid is very stable and not
decomposed when boiled with HNOg.

HydroxymetheneSulphonic Acid.CHj/gQ^jj, or oxy-methyl sulphonic

acid, CH2(OH).S08H, is formed when SO3 acts upon methyl alcohol, and the
product is boiled with water. Very likely a compound is first produced m this
reaction which is analogous to ethionic acid (p. 319). It crystallizes with difficulty
and is very stable. The barium salt crystallizes in small anhydrous plates.

In addition to the preceding acid we have oxymethene disulphonic acid,
CH(0H)<;^|q3H anijinethine trisulphonic acid, CH(S03H)3.

Ethylene Disulphonic Acid, CjH^/Iq^h, is produced by oxidizing glycol
mercaptan and ethylene sulphocyanate with concentrated njtric acid ; by acting

3l8 ORGANIC CHEMISTRY.

upon alcohol or ether with fuming sulphuric acid ; and by boihng ethylene bromide
with a concentrated solution of potassium sulphite : —

C,H,Br, + 2KS0,.0K = C,H,/|g2;°^ + 2KBr.

The acid is a thick liquid, readily soluble in water, and crystallizes with difficulty.
When it yields crystals these fuse at 94°. The barium salt, C2H^(S03)2Ba, crys-
tallizes from water in six-sided plates. Ethylene Disulphinic Acid, CjH^
(SOaH)^, results from the reduction of ethylene disulphonic acid.

CHj.OH
Hydroxyethylene Sulphonic Acid, | , Isethionic

CHj.SOsH
Acid, oxyethysulphonic acid, C2H4(OH).S03H, is isomeric with
ethyl sulphuric acid, S04H(C2H5), and is produced by oxidizing

monothioethylene glycol, CjHj/ „„ , with HNO3; by the action of

I nitrous acid upon taurine (below) : —

\

by heating ethylene chlorhydrin with potassium sulphite : —

C^H./OH ^ KS03K= C^H./g^^^j^ + KCl;
and further by boiling ethionic acid (p. 319) with water.

Preparation. — Conduct the vapors of SO3 into strongly cooled, anhydrous
alcohol or ether, dilute with water and then boil for several hours. The fluid will
contain isethionic, sulphuric, and some methionic acids. It is next saturated with
barium carbonate, and the barium sulphate removed by filtration. When the so-
lution is evaporated barium methionate crystallizes out first, and after further con-
centration barium isethionate {Berichte, 14, 64, axiA Annalen, 223, 198).

isethionic acid is obtained as a thick liquid, which solidifies when
allowed to stand over sulphuric acid. Being a sulphonic acid, it is
not decomposed when boiled with water. Its salts are very stable
and crystallize well.

The barium salt is anhydrous. The ammonium salt forms rhombic plates,

which fuse at 135°, and at 210-220° it changes to di-isethionic acid {Berichte, 14,

65). Ethyl isethionate, C2H4{OH).S03.C2H5, boils at I20°, and is formed in the

distillation of the diethyl sulphuric ester (p. 149; see Berichte, 15, 947). Chromic

acid oxidizes the isethionic acid to sulpho-acetic acid.

/CI
PCI5 converts the acid or its salts into the chloride, C^H^T <,« p, , a liquid,

boiling at 200°. When it is boiled with water it is converted into chlorethyl-
sulphonic acid, CH^Cl.CHj.SOjH [Annalen, 223, 212).

TAURINE. — ETHIONIC ACID. 319

CH,.NH,

Taurine, CaHjNSOs, Amido-ethylsulphonic acid, | ,

CH2.SO3H
occurs as taurocholic acid, in combination with cholic acid, in the
bile of oxen and many other animals, and also in the different ani-
mal secretions. It can be artificially prepared by heating chlor-
ethylsulphonic acid, CHjCl.CHj.SOgH (from isethionic acid with
PCI5), with aqueous ammonia and by the union of vinylamine (p.
163) with sulphurous acid, when they are evaporated together: —

C2H3NH, + SO3H, = CaH^/^^^2^ (Berichte, 21, 2667).

Taurine crystallizes in large, monoclinic prisms, insoluble in
alcohol, but readily dissolved by hot water. It melts and decom-
poses about 240°.

Taurine contains the groups NHj and SO3H, and is, therefore,
both a base and a sulphonic acid. But as the two groups neutralize
each other the compound has a neutral reaction. It can, however,
form salts with the alkalies. It separates unaltered from its solution
in acids (see Glycocoll).

Nitrous acid converts it into isethionic acid (p. 318). Boiling
alkalies and acids do not affect it, but when fused with caustic
potash it breaks up according to the equation : —

C2H4<^S(?3k + ='^°'^ = C2H3KO, + SO3K, + NH3 + H,.
By introducing methyl into taurine we obtain tauro-betalne, analogous to
betaine (p. 316) : [a^^)^^(^^^^'&0^.

Carbyl Sulphate, CgH^S^Og {Annalen, 213, 210), is formed when the vapors
of SO3 are passed through anhydrous alcohol. It is the anhydride of ethionic
acid : —

CH,— 0-SO,— \^ CH,-0— SO,.OH

CH.-SO^--^ CH.-SO^.OH.

Carbyl Sulphate. Ethionic Acid.

It is also produced in the direct union ot ethylene with two molecules of SO3.
It is a deliquescent, crystalline mass, fusing at 80°. With water it yields Ethionic
Acid, C^H^/'?^?!^. The constitution of the latter would indicate it to be

both a sulphonic acid and primary sulphuric ester. It is therefore dibasic, and on
boiling with water readily yields sulphuric and isethionic acids : —

320

ORGANIC CHEMISTRY.

Ethidene Sulphonic Acids. The following grouping is intended to express
the relations of the sulphonic acids of this group with those of ethylene and the
corresponding carboxylic acids : —

CH„.OH

I

CH^.COjH
Ethylene Lactic Acid.

CHj.SOsH

Isethionic Acid.

CHj.SOjH

CHJ.SO3H

Ethylene Disulphonic
Acid.

CH,.CO,H

CH2.CO2H

Ethylene Dicarboxylic

Acid.

Succinic Acid.

CH,.CH

/OH

"\CO,H

Ethidene Lactic Acid.

Ethidene-hydroxy-sulphonic Acid.

CH,CH(|g3H

Ethidene-disulphonic
Acid.

Ethidene Dicarboxylic
Acid.
Isosuccinic Acid.

The compounds formed by the union of aldehydes with alkaline sulphites
(p. 189), are viewed as salts of ethidene-hydroxy-sulphonic acid : —

CH3.CHO + SO3KH = CHj.Cn/g^j^

The potassium salt is anhydrous and forms needles ; the sodium salt, CjH^

(OHj.SOjNa + HjO, consists of shining leaflets. When these are heated with

water they decompose into aldehyde, water and sulphites.

/CI
Ethidene Chlorsulphonic Acid, CHj.CH;' o(-> xi! a-chlorethyl sulphonic acid,

is obtained by heating ethidene chloride to 140° with aqueous neutral sodium sul-
phite. The acid is quite stable ; its salts crystallize well. The sodium salt
forms pearly leaflets.

Ethidene Disulphonic Acid, CH3,CH(S03H)2, results when thioaldehyde, or
thialdine, is oxidized with MnO^K. It forms very stable salts {Berichte, 12, 682).

When ethyl iodide acts upon its silver salt the product is the diethyl ester,
CH3.CH(S03.C2H5)j. This is an oil, insoluble in water and caustic soda. The
hydrogen of its CH-group can be exchanged for sodium by the action of sodium
alcoholate and then by alkyls. Herein it resembles sulpho-acetic ester and malonic
ester, (p. 262) (Berichte, 21, 1551).

ALDEHYDE ALCOHOLS.

These contain both an alcoholic hydroxyl group and the aldfehyde group CHO,
hence their properties are both those of alcohols and aldehydes (p. 296). The
addition of 2 H-atoms changes them to glycols, while by oxidation they yield the
oxy-acids.

KETONE-ALCOHOLS. 32 1

(1) G/ycalyi A/deAyJe, CH^{OlV).CtiO, may he considered the first aldehyde
of glycol, and glyoxal (p. 324) the second or dialdehyde.

(2) Aldol, QHsO^ = CH3.CH(OH).CH2.CHO, /9-oxybutyr-
aldehyde. This is obtained by letting dilute hydrochloric acid act
upon crotonaldehyde (p. 199) and acetaldehyde : —

CH3.CHO + CH3.CHO = CH3.CH(OH).CH2.CHO.

A mixture of acetaldehyde and dilute hydrochloric acid, prepared in the cold, is
permitted to stand 2-3 days, at a medium temperature, until it has acquired a
yellow color. It is then neutralized with sodium carbonate, shaken with ether,
the latter evaporated, and the residual aldol distilled in a vacuum (^Berichle, 14,
2069).

Aldol is a colorless, odorless liquid, with a specific gravity of
1. 120 at 0°, and is raiscible with water. Upon standing it changes
to a sticky mass, which cannot be poured. Aldol distils in a vacuum
undecomposed at 100° ; but under atmospheric pressure it loses
water and becomes crotonaldehyde :^-

CH3.CH(OH).CHj.CHO = CHj.CHiCH.CHO + Hfi.

As an aldehyde it will reduce an ammoniacal silver nitrate solu-
tion. Heated with silver oxide and water it yields /J-oxybutyric
acid, CH3.CH(OH).CH2.C02H.

On standing it polymerizes into paraldol, {Cfi.f)^-a. , which melts at 80-90°.
Should the mixture of aldehyde and hydrochloric acid used for the preparation of
aldol stand for some time, water separates, and we obtain the so-called dialdan,
CgHnOg. This melts at 139°, and reduces ammoniacal silver solutions.

Ammonia converts aldol in ethereal solution into aldol-ammonia, C^HjO^.NHj,
a thick syrup, soluble in water. When heated with ammonia we get the bases,
CgHisNOj, CgHijNO (oxytetraldin, p. 199) and CgHuN (coUidine). With aniline
aldol forms methyl quinoline.

KETONE-ALCOHOLS.

These compounds contain both the ketone and alcohol groups. A simpler desig-
nation for them is ketoh. They are distinguished, with reference to the relative
position of the two groups, as a-, /3-, y-, or (1.2)-, (1.3)-, etc., ketols (compare
diketones, p. 325) [Berichte, 22, 21 14). Being ketones, the ketols unite with the
primary alkaline sulphites, with phenylhydrazine, etc.

Acetyl Carbinol, Methyl Ketol, Acetol, CH3.CO.CH2.OH, is only known
in aqueous solution. It is obtained from monobromacetone by the action of silver
oxide or potassium carbonate, and by fusing cane and grape sugar with caustic
alkali {Berichte, 16, 837). Acetol, its ethyl ether, and its esters may be formed
from the corresponding propargylic compounds by hydration with HgEr, (p. 87) :—

CHiC.CHj.OH -f H2O = CH3.CO.CH2.OH.
27

322 ORGANIC CHEMISTRY.

Its solution reduces alkaline copper solutions even in the cold. The ethyl
ether, CgHsO.O.CjH^, boils at 128°. It is produced by the action of sodium
upon chloracetic acid. Its phenylhydrazone yields an indol derivative when heated
{Berickte, 21, 2649). The acetyl ester, CjHsO.O.C^HjO.is obtained from chlor-
acetone, CHj.CO.CHjCl, by heating the latter with potassium acetate and alcohol.
It boils at 172°, and is readily soluble in water. The benzoyl ester, CgHjO.O.CjHjO,
melts at 24°. The esters reduce warm alkaline copper solutions, forming o-lactic
acid [Berichte, 13, 2344) : —

CHg.CO.CHj.OH + O = CH.,.CH(OH).CO.OH.

Acetol. a-Lactic Acid.

Acetol combines with 2 molecules of phenylhydrazine and forms the osazone,
CH3.C(N2H.C5H5).CH(N2H.CeH5) (see the osazones, and Berichte, ai, Ref.
98). In this respect it resembles the glucoses.

Homologous Acetols, R.CO.CHjOH, have been obtained as ethers from the
halogen derivatives of alkylized acetoacetic esters (Berichte, 21, 2648).

Acetyl-methyl Carbinol, C4H50j= CH3.CH(0H).C0.CHjj, or Dimethyl
Ketol, corresponds to benzoin of the aromatic series. It is prepared by reducing
diacetyl (p. 326) with zinc and sulphuric acid. It is a liquid, boiling at 142°. It
is miscible with water, and reduces Fehling's solution. It yields the osazone ol
diacetyl {Berichte, 22, 2214) when heated with phenylhydrazine.

The following is a y-, or (i.3)-Ketol: —

Acetopropyl Alcohol, C^,f>^ = CHo.CO.CHj.CH^.CHjOH, is obtained from

bromethyl acetoacetic ester, CH-.CO.CH^ rci^V' w' (from acetyl Irimethylene

carboxylic ester), upon boiling with hydrochloric acid. It is a mobile liquid,
of peculiar odor, and boils at 208°. It does not reduce either an ammoniacal
silver solution or Fehling's solution. When slowly distilled it separates into water
and an anhydride (a pleasant-smelling liquid, boiling about 75°). The latter can
be considered a methyl-dihydrofurfurane, 0^115(0113)0. Acetopropyl alcohol
yields a hydrazone anhydride with phenylhydrazine. Chromic acid oxidizes it to
Isevulinic acid {Berichte, 21, 1 196; 22, Ref. 572).

Hydrobromic acid converts the alcohol into brom-fropyl-methyl ketone, CH3.CO.
CH^.CHjCHjBr. This, like the y-diketones (p. 328), yields a pyrrol derivative when
heated with ammonia {Berichte, ig, 2844).

Acetobutyl Alcohol.CjHj^Oj = CHg.CO.C,Hg.CHj.OH, is obtained by boiling
brom-propyl acetoacetic ester, CH3.CO.CH/pJ?2'^w''*^^2Br^ ^^j^ hydrochloric

acid {Berichte, 18, 3277); also from acetyl teti amethylene carboxylic ester {Be-
richte, ig, 2558). It is a liquid, very soluble in water, alcohol and ether, and has
an odor resembling that of camphor. It boils about 155°. It does not reduce either
an ammoniacal silver solution, or Fehling's solution. Sodium amalgam converts
it into rf-hexylene glycol (p. 310) ; while chromic acid oxidizes it to y-aceto-
butyric acid. Boiling HBr-acid converts it into brom-butylmethyl ketone, CH,.
CO.CjHj.CHjBr. This is a liquid, boiling at 21.6°. It forms a pyridine derivative
(tetrahydropicoline) (Berichte, ig, 2844), when heated with ammonia. In this
respect it is like the a-diketones.

Diacetone Alcohol, CgHj^O.^ = CH3.CO.CH,.C(CH3).pH, is obtained from
diacetonamine (p. 208) by the action of nitrous acid. A liquid, miscible with water,
alcohol and ether. Specific gravity = 0.930 at 25°. It boils at 164°. Mixed
with sulphuric acid it parts with water and becomes mesityl oxide (p. 208).

KETON-ALDEHYDES.

K ETON- ALDEHYDES.

323

Pyroracemic Aldehyde, CH,.CO.CHO, Acetyl-formyl or Methyl Glyoxal,
is obtained by boiling isonitroso-acetone (p. 206) with dilute sulphuric acid (this is
analogous to the formation of the a-diketoues, p. 325). Hydroxylamine is split
off in this reaction (see the oximes, p. 202) : —

CH3.C0.CH:N.0H + H^O = CH3.CO.CHO + NH^.OH;

a volatile yellow oil. It reduces an ammouiacal silver solution. It forms a hydra-
zone very readily {Berichte, 20, 3218). It yields an osazone, CjsHjjN^, with
2 molecules of phenylhydrazine ; the same compound is obtained from acetol
(p. 321). {Berichte, 21, Ref. 98).

^-Keton-aldehydes, general formula R.CO.CHj.COH, are synthetically pre-
pared by the interaction of ketones, R.CO.CH3, and formic acid esters, in the
presence of sodium alcoholate. The sodium compounds first result (Claisen, Be-
richte, 20, 2191 ; 21, Ref. 915 ; 22, 3273) : —

R.CO.CH3 -f CHO.O.C3H5 + NaO.C^Hj = R.CO.CHNa.CHO + 2C2H5OH.
Formic Ester,

The ketones R.CO.CH^R react similarly with these esters, but not those of the
type R.CO.CHRj. This is explained by assuming that an earlier union occurs
between the acid ester and sodium ethylate [Berichte, 22, 533).

The keton-aldehydes, R.CO.CH^.CHO, and R.CO.CHR.CHO, like the /3-di-
ketones, R.CO.CH^.CO.R, are acid in their nature. The hydrogen of the groups
CHj and CHR is readily replaced by metals. They dissolve in alkaline carbo-
nates to form salts, c. g., R.CO.CHNa.CHO. They produce green-colored pre-
cipitates with copper acetate [Berichte, 22, 1018). Ferric chloride imparts a deep
violet or red color to their alcoholic solutions [Berichte, 22, 3277). They readily
yield oximes, anilides, benzene azo-derivatives [Berichte, 21, 1699), hydrazones,
pyrrazoles, isoxazoles, etc.

The keton-aldehydes, R.CO.CHR.CHO, are very unstable when free. They
condense readily. Their sodium and other salts are, however, very stable. The
monoalkylic keton-aldehydes, R.CO.CHR.CHO, are so constituted that they can-
not sustain analogous condensation, hence they are stable when in a free condi-
tion, and can generally be distilled [Berichte, 22, 3274).

Acetyl aldehyde, CHg.CO.CHj.CHO, Formyl acetone, from acetone and
formic ester, is a liquid, boiling near 100°. Its odor resembles that of acetoacetic
ester and of acetone. Ferric chloride colors it a deep red. It readily condenses,
even in solution, to triacetyl benzene : —

3CH3.CO.CH,.CHO = C3H3(CO.CH3)3 + 3H,0.

It forms methyl-phenyl-pyrrazole with phenylhydrazine [Berichte, 21, 1144).

Propionyl Aldehyde, CrHj.CO.CHj.CHO = C ^'B. fi ^, formyl methyl-ethyl
ketone, results from methyl-ethyl ketone and formic ester. It yields ethyl -phenyl
pyrrol with phenylhydrazine.

Propionyl-propionic Aldehyde, CjHjoOj = C^^.CO.Cii(^^^-^Q, formyl

diethyl ketone, from diethylketone, is stable when free (see above). It consists ot
crystals having a peculiar odor. They melt at 40°. For additional keton-alde-
hydes consult Berichte 22, 3277.

324 ORGANIC CHEMISTRY.

DIALDEHYDES.

The only known dialdehyde of the fat series is glyoxal.

Glyoxal, C^HA = CHO.CHO, Diformyl, is the dialdehyde
of ethylene glycol, while glycolyl aldehyde (p. 321) represents the
first or half aldehyde : —

CH.OH CH„OH CHO

I I I

CH^OH CHO CHO

Glycol. Glycolyl Aldehyde. Glyoxal.

Glyoxal, glycollic acid and glyoxylic acid are formed in the careful
oxidation of ethylene glycol, ethyl alcohol, or acetaldehyde with
nitric acid.

In preparing glyoxal, alcohol, or better, aldehyde and fuming nitric acid are
placed, layer after layer, in narrow glass cylinders, using a funnel tube for the
introduction of the acid. Let the whole stand for 5-6 days (Berichte, 14, 2685).
The residue obtained by evaporation of the mixture to syrup consistence contains
chiefly glyoxal, with a little glycollic acid and glyoxylic acid. These can be-
removed in the form of calcium salts. To obtain the glyoxal, the residue is directly
treated with a concentrated solution of primary sodium sulphite, when the double
salt with glyoxal (see below) will crystallize out (^Berichte, 17, 169).

On evaporating the solutions the glyoxal is obtained as an amorphous, non-vola-
tile mass. It deliquesces in the air. It is very soluble in both alcohol and ether.
In this condition it is probably a polymeric modification (C2H202)2, because
methylglyoxal (p. 323) and dimethyl glyoxal (p. 326) are very volatile (^Berichte,
21, 809). The alkalies convert it, even in the cold, into glycollic acid.

In this change the one CHO group is reduced, while the other is oxidized
(compare benzil and benzilic acid) : —

CHO CH2OH

I +H20 = |
CHO CH2OH.

As a dialdehyde it unites directly with 2 molecules of primary sodium sulphite,
forming the crystalline compound, C2H203(SOjHNa)2 -|- HjO. It also reduces
ammoniacal silver solutions.

With ammonium cyanide and hydrochloric acid, glyoxal forms diamido-succinic
acid (p. 190). It also yields a dioxime with two molecules of hydroxylamine ;
this is the so-called Glyoxime, CH(N.OH).CH(N.OH) (p. 207). This is also
produced when hydroxylamine acts upon trichlorlactic acid [Berichte, 17, 2001).
It is soluble in water, alcohol and ether. It crystallizes in rhombic plates, melts
at 178°, and sublimes without difficulty. It has a faintly acid reaction and forms
salts with the bases.

As to the deportment of other dialdehydes towards hydroxylamine see Berichte,
20, 507.

See Berichte, 21, Ref. 636, for the compounds of glyoxal with malonic and aceto-
acetic esters.

Glyoxal combines with 2 molecules of phenylhydrazine and yields —

CH:N2H.C,H5

Glyoxal Diphenyl Hydrazine, | . This derivative can also

CH:N2H.C5H5

DIKETONES. 325

be prepared from trichlorlactic acid {Berichte, 17, 20Ol). It crystallizes in needles
or leaflets, melting at 170°. Its HCI-salt is a yellow-colored compound {Berichte,
19, Ref. 303).

Glyoxal and orthophenylene diamines unite and form quinoxaline derivatives
(see these).

Concentrated ammonia yields two bases with glyoxal : Glycosin, CJH5N4, of
unknown constitution, and in larger quantity, Glyoxaline, CjH^N^, the parent
substance of the glyoxalines (oxalines), or amidazoles (/3-diazoles) (see these).
/CHO CHj.CHO

Malonyl Aldehyde, CH,Q rvjr\' ^^^ Succinyl Aldehyde, 1 , have

^'^"^ CHj.CHO

not been obtained. They are the aldehydes of trl- and tetramethylene glycols.
CH^.CHCN.OH)
Succinyl Aldoxime, | , results from the action of hydroxyla-

CH2.CH(N.0H)
mine upon pyrrol. It yields tetramethylene diamine when reduced with metallic
sodium (p. 313) {Berichte, 22, 1968).

DIKETONES.

The diketones contain two ketone groups, — CO. The relative
position of these groups determines them to be either a-, /?-, or
j'-diketones,-etc. Peculiar characteristics distinguish these classes.

(i) a-Diketones, R.CO.CO.CH3.

The a-, (or 1.2) -diketones have their two CO-groups united
directly to each other. In the aromatic series they are called ortho-
diketones (see these). They may be regarded as diketo-substituted
ethanes. Hence, the name a/9-diketo-butane for the compound,
CH3.CO.CO.CH3 (seep. 201); or they can be viewed as compounds
of two acid radicals (that cannot exist uncombined) (p. 246) : —

CHj.CO^ CHj.CO^ .

CH3.CO -^ C,H5.C0/

Diacetyl. Acetyl-propionyl.

The a-diketones are prepared by boiling the isonitrosoketones
(same as acetyl formyl from isonitrosoacetone, p. 323) with dilute
sulphuric acid (p. 206) (v. Pechmann, Berichte, 20, 3213) : —

CH3.CO.C(N.OH).CH3 + Hp = CH3.CO.CO.CH3 + NH,.OH.

The solutions obtained by the action of nitrous acid upon mono-alkyl-acetoacetic
esters may be used for this purpose, instead of the prepared nitrosoketones {Ber-
ichte, 21, 141 1 ). At times nitrous acid effects the decomposition more rapidly than
sulphuric acid {Berichte, 22, 532, 527).

The a-diketones are yellow-colored, volatile liquids. They possess a penetratmg
odor They yield monoximes with one molecule of hydroxylamine. These com-
pounds are also called ketoximes {Berichte, 21, 2994). With 2 molecules ot
hydroxylamine* they form the dioximes (glyoximes or acetoximic acids, p. 203).
These can form anhydrides (see benzildioxime or diphenylglyoxime). The
a-diketones with I molecule of phenylhydrazine yield vionohydrazones (or keto-

326 ORGANIC CHEMISTRY.

hydrazones), and with 2 molecules of phenylhydrazine the dihydrazones, called
also osazones.*

The osazones are bright red, crystalline compounds. When digested with
alcohol and ferric chloride they produce reddish-brown colorations, soluble in
ether (reaction of Pechtnann). Oxidation takes place and the osotetrazones
result : —

CH,.C:N,H.C.H5 CHj.CiN.N.CeHj

I +0= '1 '+H,0.

CHa.C-.NjH.CjHs CH3.C:N.N.CjH5

These split off one phenyl group and pass into the osotriazones {Berichie, 21,
2751).

-Vhehydrazoximes, e.g., CH3.C(N.OH).C(N2H.C,H5).CH3, diacetyl hydrazox-
ime, are compounds of the diketones with I molecule of liyHroxylamine and I
molecule of phenylhydrazine. They form when phenylhydriizine acts upon the
mon-oximes, or hydroxylamine upon the mono-hydrazones (or ketohydrazones)
[Berichte, 21, 2994).

The a-diketones are characterized and distinguished from the /3-, and y-ketones
by their ability to unite with the orthophenylene diamines (similarto glyoxal). In
this way they are condensed to the quinoxalines (see these) : —

.NH„ CO.R ,N:CR

C6H4( + I = CeH / I + 2H,0.

^NH^ CO.R \N:CR

All compounds containing the group — CO.CO— , e. g., glyoxal, pyroracemic
acid, glyoxylic acid, alloxan, dioxytartaric acid, etc., react similarly with the
o-phenylene diamines. The glyoxalines are the products of the union of the
a-diketones with ammonia and the aldehydes, a- Diketones, containing a CH^-
group, together with the CO-group, sustain a rather remarkable condensation when
acted upon by the alkaUes. Quinogens are first produced, and later the quinones
{Berichie, 21, 1418; 22, 2215) : —

CH,.CO.CO.CH3 CH3.C.CO.CH3 CH3.C.CO.CH

II yield II and || \

CH,.CO.CO.CH, CH.CO.CO.CH3 CH.CO.C.CH3.

2 Molecules Diacetyl. Dimethyl-quinogen. p-Xyloquinone.

(i) Diacetyl, eH3.CO.CO.CH3, Diketobutane, Dimethyl diketone, from
isonitrosomethylacetone or methyl acetoacetic ester (p. 209) [Berichte, 21, 141 1),
has also been obtained from oxalyldiacetic acid (ketipic acid) by the splitting-off
of the carboxyls upon the application of heat (Berichte, 20, 3183). It is a yel-
low liquid, with an odor like that of quinone. It boils at 87-89°. It dissolves
rather readily in water, and is miscible with both alcohol and ether. Sulphurous
acid decolorizes the yellow solution. HCl-hydroxylamine precipitates the dioxime,
C4Hg(N.OH)2 ; this melts at 234°. The m.onophenylhydrazone,C.^fi{J^^.C^X
is also formed from methyl acetoacetic acid and benzene diazochloride. It melts
at 133°. The dihydrazone, C^^(^,^.Cfi.^^ (see above), melts at 242°. It has
been obtained from the hydrazone of pyroracemic acid (Berichte, 2i, 549)-

*The a-aldehyde alcohols and aketon alcohols (p. 321) yield similar osazones
with 2 molecules of phenylhydrazine. An atom of oxygen from the air acts at
the same time (just as with the osazones of the glucoses).

DIKETONES.

327

Two molecules of CNH convert diacetyl into dicyanhydrin, CiHjfOH) (CN).
(see p. 202). The latter yields dimethyl racemic acid iBerUhte, 22, Ref. 137).

Tetrachlor-diacetyl, CHClj.CO.CO.CHCl^, results in the action of potassium
chlorate upon chloranilic acid (together with tetrachloracetone, p. 205). It crys-
tallizes in yellow plates, melting at 84°. It yields a quinoxaline derivative with
ophenylenediamine, and a dihydrazone with phenylhydrazine (Berichte, 22, Ref
809; 23, Ref. 20).

Tetrabrom-diacetyl, QHjBr^j {Berichte, 23, 35) and Dibrona-diacetyl,
(CHjBr.CO)^, are produced by the action of bromine upon diacetyl.

(2) Acetyl-propionyl, CjHj.CO.CO.CHg, Methyl-ethyl-diketone, from iso-
nitroso-ethylacetone, or ethyl acetoacetic ester, is very similar to diacetyl. It boils
at 108° {Berichie, 22, 21 17).

Acetyl-butyryl or Methyl-propyldiketone, CjHj.CO.CO.CHj, Acetyl-iso-
butyryl, etc., as well as the mixed a-diketones of the paraffin and aromatic series,
are analogous compounds {Berichte, 22, 2127).

(2) '?- (or i.3)-Diketones, R.CO.CH^.CO.R.

In these compounds the two carbonyls are separated by an inter-
vening C-atom. They are frequently formed by the breaking down
of acidyl-acetoacetic esters (see benzoyl acetone). The usual course
is analogous to the reaction by which the keton-aldehydes (p. 323)
are produced. It consists in the interaction of acetic esters and
ketones in the presence of sodium ethylate, or better, metallic sodium
(Claisen, Berichte, 22, 1009 ; 23, Ref. 40) : —

CH3.CO.CH3 + C2H5.O.CO.CH3 = CH3.CO.CHj.CO.CH3 -f C2H5.OH.

Ethyl Acetate. Acetyl Acetone.

The /3-diketones, like the /3-ketonaldehydes (p. 323) have an acid character.
An H-atom of the CHj-group can be replaced by metals (this is similar to the
^-ketonic esters). They are, therefore, soluble in caustic alkalies, forming alkali
salts, and with copper acetate they generally yield precipitates of copper salts
{^Berichte, 22, 1017). Ferric chloride imparts an intense red color to their alco-
holic solution. They combine with i molecule of hydroxylamine with the separa-
tioiyof two ipolecules of water. The products are the remarkable oxime-anhy-
drides. These belong to the so-called oxyazoles (see these, and Berichte, 21,
if78).

' With phenylhydrazine the /3diketones (and all other compounds containing the
groups — CO.CHg.CO — ) -j\t\6i fyrrazole compounds (see these). Methylphenyl-
hydrazine, however, converts them into hydrazones {Berichte, 22, Ref. 671).

Acetyl-acetone, CjHgOj = CH3.CO.CHj.CO.CH3, Diacetylmethane, (CH3.
CO)2CH2, was first prepared by digesting acetyl chloride with AICI3 {Berichte, 22,
1009). It is most easily obtained by the action of metallic sodium upon acetone
and acetic ester {Berichte, 23, Ref. 40)'. It is a colorless liquid, boiling at 137°,
and very readily soluble in ether. It dissolves in the caustic alkalies, and splits up
into acetone and acetic acid. Its copper salt, (C5H,Oj)2Cu (see above), is precipi-
tated as a blue-colored, crystalline precipitate. Phenylhydrazine converts it into
dimethylphenyl pyrrazole, and with diazobenzene-chloride yields an azo-derivative
{Berichte, 21, 1699).

Acetyl-methyl-ethyl Ketone, CHj.CO.CHj.CO.CjHj = CjHioO^, acetyl-
propionyl methane, from methylethyl ketone and acetic ester, boils at 158°. Its
sp. gr. is 0.9538.

Acetyl-methylpropyl Ketone, CjHjjOj = CHj.CO.CHj.CO.CsH,, acetyl-
butyryl methane, boils at 161° {^Berichte, 22, 1015).

328 ORGANIC CHEMISTRY.

Diacetylacetone, CO(^^|[^2-CO.CH3^ j^ ^ ^ triketone. It apparently is formed

from dimethylpyrone [Berichte, 22, 1570).
CO.CH2.CO.CH3
Oxalyldiacetone, I , is an a/3-tetraketone. It is produced

CO.CHj.CO.CH3
when sodium ethylate acts upon oxalic ester and acetone. It melts at 121° and
dissolves easily in alcohol and ether. Ferric chloride colors it a brownish red
{Berichte, 21, 1141).

3. ^'-Diketones, R.CO.CH^.CH^.CO.R.

These correspond to the paraquinones of the aromatic series (see
these). They are not capable of forming salts, hence are not soluble
in the alkalies. They form mono- and di-oximes with hydroxyl-
amine, and mono- and di-hydrazones with phenylhydrazine ; these
are colorless. The readiness with which the ^--diketones form
pyrrol, furfurane, and thiophene derivatives is characteristic of
them.

Acetonyl Acetone, QHioO^ = CH3.CO.CH2.CHj.CO.CH3,
diacetylethane, is obtained from pyrotritartaric acid, C^HsOs (see
this), and from acetonyl acetoacetic ester (p. 336), upon heating to
160° with water {Berichte, 18, 58), and from isopyrotritartaric acid,
and diacetylsuccinic ester, when they are allowed to stand in con-
tact with sodium hydroxide {Beri'chte, 22, 2100). A liquid with
an agreeable odor. It is miscible with water, alcohol and ether.
It boils at 188° C.

It unites to a dioxime with 2 molecules of hydroxylamine. This new derivative
crystallizes in shining leaflets, melting at 136°. It is also produced by the action
of hydroxylamine upon (l.4)-dimethylpyrrol (Berichte, 22, 3177). With 2 mole-
cules of phenylhydrazine it yields a di-hydrazone, melting at 120°. Monophenyl-
hydrazone, by the loss of 2 molecules of water, passes into a pyrrol derivative
{Berichte, 22, 170). Dimethyl pyrrol is produced on heating acetonyl acetone
with alcoholic ammonia (Paal, Berichte, 18, 58, 367) : —

CHn.CO.CHj CH = C,{ vrtj' I -,tr r\
CH2.CO.CH3 ^^ t _ CH3

Dimethyl Pyrrol.

All compounds containing two CO-groups in the (1.4) position react similarly
with ammonia and amines. Such are diacelo-succinic ester and Isevulinic ester.
All the pyrrol derivatives formed as above, when boiled with dilute mineral
acids, have the power of coloring a pine chip an intense red. This reaction
is, therefore, a means of recognizing all (i.4)-diketone compounds {Berichte, 19,
46).

These derivatives react similarly with amidophenols and amido-
acids (^Berichte, 19, 558).

CH2.CO.CH3

CH =

1 +SH,

= 1

CH,.CO.CH,

CH =

ALDEHYDE ACIDS. 329

When heated with phosphorus sulphide acetonyl acetone yields
dimethyl thiophene (Paal, Berichte, 18, 2251): —

/CH3

\S + 2H2O.

\CH3

Dimethyl Thiophene.

All the ;'-diketones or (i.4)-dicarboxyl compounds, e. g., the
^--ketonic acids (p. 343), yield the corresponding thiophene deriva-
tives upon like treatment {Berichte, 19, 551).

The direct removal of one molecule of water from acetonyl
acetone (by distillation with zinc chloride or P2O5) affords dimethyl
furfurane {Berichte, 20, 1085): —

/CH3
CHj.CO.CHj CH = C(
'I =1 )0 +H,0.

CH,.C0.CH3 CH=C(

\CH3
Dimethyl Furfurane.

Other T'-diketone compounds react in a similar manner (Knorr,
Berichte, 17, 2756).

In all these conversions of acetonyl acetone into pyrrol, thio-
phene, and furfurane derivatives it may be assumed that it first
passes from the diketone form into the isomeric or tautomeric form
of the unsaturated dihydroxyl (p. 54) : —

CH2.CO.CH3 CH = C('^^3

I yields I ,Qjj ,

CH2.CO.CH3 CH = C('gg

and from this, by replacing the 2OH groups with S, O, or NH,
the corresponding furfurane, thiophene and pyrrol compounds are
produced {Berichte, ig, 551).

(1.5) or (!-Diketones.

Derivatives of this class are produced when benzaldehyde acts upon esters of
diazoacetic acid {Berichte, 18, 2372) and upon aeetoacetic ester [Berichte, 18,
2583). They do not yield pyridine derivatives with ammonia.

ALDEHYDE ACIDS.

These are the compounds containing both the CHO and the
COjH groups. Their properties are both those of the aldehyde and
the acid. The only member of this class in the fat series is Gly-
oxylic Acid.
28

33° ORGANIC CHEMISTRY.

CHO CH(OH),

Glyoxylic Acid, QH^Oj = | or QHA = | ,

CO2H CO. OH

glyoxalic acid. The aldehydes frequently yield hydrates by eom-
bining with one molecule of water ; these derivatives are regarded
asdihydroxyl compounds (see chloral hydrate, p. 196). Glyoxylic
acid exhibits similar behavior. The free crystalline acid has the
formula, C2H2O3.H2O = C2H4O4; all its salts are obtained from it.
Hence, we must consider it a dihydroxyl compound, which may be
designated a dioxy-acetic acid. By withdrawal of water, the alde-
hyde group is produced, and the acid conducts itself as a true alde-
hyde acid.

Glyoxylic acid is obtained by oxidizing glycol, alcohol and alde-
hyde (p. 324). It is most readily prepared by heating dichlor- and
dibrom-acetic acid to 120° with water: —

CHCI2.CO2H + 2H2O = CH(OH)2.C02H -I- 2HCI.

It is a thick liquid, readily soluble in water, and crystallizes in
rhombic prisms by long standing over sulphuric acid. The crystals
have the formula, CjH^Oj. It distils undecomposed with steam.

As a monobasic acid it forms salts with one equivalent of acid. When dried at
100°, the salts have the formula, CjHjMeO^. The ammonium salt alone has the
formula, C2H(NH4)03. The calcium salt, {C^^O^^Ca., crystallizes with one
and two molecules of water {^Berichte, 14, 585), and is sparingly soluble in water
(in 140 parts at 18°). Lime water precipitates an insoluble basic salt from its solu-
tion. The silver salt, C^HjAgO^, is a white, crystalline precipitate.

Again, glyoxylic acid manifests all the properties of an aldehyde. It reduces
ammoniacal silver solutions with formation of a mirror, and combines with primary
alkali sulphites. When oxidized (silver oxide) , it yields oxalic acid; by reduction
(zinc and water) it forms glycoUic acid : CHO.CO^H + Hg =CH2(OH.)C03H.
On boiling the acid or its salts with lime water, or alkalies, glycollic and oxalic
acids are produced [Berichle, 13, 1392) : —

CHO CHj.OH CO.OH

I + H,0 = I +1

CO.OH CO.OH CO.OH

This is analogous to the transposition of aldehydes to alcohol and acid (p. 1 89).
When hydrocyanic and hydrochloric acids act upon glycollic acid, a like transposi-
tion ensues.

Phenylhydrazine unites with glyoxylic acid to phenyl-hydrazine-glyoxylic acid,
CH(N2H.CsH5).C02H {Berichte, 17, 577).

Homologous /?-aldehydic acids (their esters) are produced (analogous to the ^-
ketonic esters, p. 338) by the action of sodium, or sodium ethylate, upon amixture
of formic ester and acetic ester (or other esters) {^'mSiS, Berichte,7a,^%T; W.
Wislicenus, Berichte, 20, 2930) : —

CHO.O.C2H5 -f CH3.CO2.C2H5 = CHO.CHj.COj.CjHj -I- C2H5.OH.
Formic Acetic Formyl Acetic

Ester. Ester. Ester.

KETONIC ACIDS. 33 1

Formyl Acetic Acid, CH2<^„q \t, may be called the half aldehyde of malonic

acid, CH2(COOH)2. Its ethyl ester, from acetic and formic esters, is very unstable.
It condenses immediately {analogous to the condensation of acetyl aldehyde to
triacetyl benzene (p. 323) to the ester of trimesinic acid : —

3CHO.CH,.CO,.C,H, = CeH3(CO,.C,H,)3 + 311,0

[Berichte, 21, 1 146).

KETONIC ACIDS.

These contain both the groups CO and CO^H ; they, therefore,
show acid and ketone characters with all the specific properties
peculiar to these. In conformity with the manner of designating
the mono- and di-substituted fatty acids (pp. 223 and 224), we
distinguish the groups a-, /?- and y- of the ketonic acids. These
differ from each other by various peculiarities : —

R.CO.COjH R.CO.CH2.CO2H R.CO.CHj.CHj.CO^H.

a-Ketonic Acids. ^-Ketonic Acids. 7-Ketonic Acids.

The a- and ;'-acids are quite stable, even in a free condition. This
is only the case with the /9-acids when in the form of esters. If they
are set free from these they readily decompose (p. 323).

The names of the ketonic acids are usually derived from the fatty
acids, inasmuch as the acid radicals are introduced into these
(p. 213); e.g.,—

CH3.CO.CO2H CH3.CO.CH2.CO2H, etc.

Acetyl-formic Acid. Acetyl-acetic Acid.

According to a more recent suggestion of A. Baeyer, these acids
should be viewed as /?:,f/^-substitution products of the fatty acids,
being formed by the substitution of oxygen for 2H in the CH^-
group {^Beruhte, 18, 160); hence the names: —

CH3.CO.CO2H CH3.CO.CH2.CO2H, etc.

o-Ketopropionic Acid. |3-Ketobutyric Acid.

In accord with their ketonic nature, they unite with alkaline sul-
phites to form crystalline compounds, from which alkalies or acids
again set them free {Berichte, 17, Ref. 568). They form oximes
or isonitroso fattv acids (p. 214) with hydroxylamine, and with
phenyl-hydrazine' phenyl-hydrazo-fatty acids. Nascent hydrogen
converts all the ketonic acids into the corresponding divalent oxy-
acids. In this change the ketonic group becomes a secondary alco-
hol group : —

CH-.CO.CO^H + H, = CH3.CH(0H).C0,H.

a-Lactic Acid.

332 ORGANIC CHEMISTRY.

I. a-J^e^onuAcids—R.CO.CO^U.

In this class the ketone group CO is in direct union with the
acid-forming carboxyl group, COjH. We can view them as com-
pounds of acid radicals with carboxyl, or as derivatives of formic
acid, HCO.OH, in which the hydrogen linked to carbon is replaced
by an acid radical — hence the designation acetyl carboxylic acid or
acetyl formic acid for the acid, CHj.CO.COjH. The first name
indicates, too, the general synthetic method of formation of these
acids from the cyanides of acid radicals (p. 247), which, by the
action of concentrated hydrochloric acid, are changed to the cor-
responding ketonic acids : —

CH3.CO.CN + 2H2O + HCl = CHo.CO.COjH + NH^Cl.
Acetyl Cyanide. Acetyl Carboxylic Acid.

(i) Pyroracemic Acid, a-Ketopropionic Acid (acetyl car-
boxylic acid), C3H4O3 = CH3.CO.CO2H, was first ojjtained in the
distillation of racemic acid, tartaric acid and glyceric acid. It is syn-
thetically prepared from a-dichlorpropionic acid, CH3.CCI2.CO2H
(p. 225), when healed with water and silver oxide, and from acetyl
cyanide by the action of hydrochloric acid (see above). Further,
by the action of concentrated hydrochloric acid upon acetyl cya-
nide. Its formation in the oxidation of ordinary lactic acid with
potassium permanganate, and by the decomposition of oxalacetic
ester, is rather remarkable. '

For its preparation heat tartaric acid in an iron pan until it chars and swells up.
After cooling, the mass is broken into pieces, placed in a retort and distilled over
a free flame [Annalen, 172, 142). A large yield (about 60 per cent.) is reached
by distilling tartaric acid with potassium bisulphate {Berichle, 14, 321). The
formation of pyroracemic acid from tartaric acid (racemic acid and glyceric acid) : —

CH(0H).C02H CH,

I = I +CO2 + H2O,

CH(0H).C02H CO.COjH

is quite similar to the transpositions cited on page 134.

Pyroracemic acid is a liquid, soluble in alcohol, water and ether,
and has an odor quite similar to that of acetic acid. It boils at
165-170°, decomposing partially into COj and pyrotartaric acid
(2C3H4O3 = CsHaOi -\- CO2). This change is more readily effected
if the acid be heated to 100° with hydrochloric acid.

The acid reduces ammoniacal silver solutions with the production of a silver
mirror, the decomposition products being CO2 and acetic acid. When heated with
dilute sulphuric acid to 150° it splits up into CO2 and aldehyde, CH3.COH. This
ready separation of aldehyde accounts for the ease with which pyroracemic acid
enters into various condensations, e.g., the formation of crotonic acid by the action

KETONIC ACIDS. 333

of acetic anhydride (p. 238), and the condensations with dimethyl aniline and
phenols {Berichte, 18, 987, and 19, 1089).

Pyruvic acid is monobasic. Its salts crystallize with difficulty. Its zinc salt,
(C5H303)2Zn -f^ 3H2O, is a. crystalline powder, soluble with difficulty in water.
AH the salts are colored red by ferric chloride.

When the acid or its salts are heated with water, or if the acid be set free from
its salts by mineral acids, it passes into a syriip-]il«e, non-volatile mass.

Pyruvic acid forms crystalline compounds with the acid alkaline sulphites.
It resembles the ketones in this respect. Nascent hydrogen (Zn and HCI, or HI)
changes it to ordinary a-lactic acid, CHg.CH(0H).C02H. PCI 5 converts it into the
chloride of a-dichlorpropionic acid, CHj.CClj.COCl (p. 225). Pyroracemic acid,
in aqueous, ethereal or acid solution, unites very readily with phenyl hydrazine to
form CH3.C(HN2.CgH5).C02H, a crystalline solid, melting at 182° with decom-
position {^Berichte, 21, 987). This reaction will serve for the detection of minute
quantities of the acid \Berichte, 16, 2242). With hydroxylamine it yields a-iso-
nitrosopropionic acid (p. 224). It combines with CNH, like all ketone compounds,
and forms an oxycyanide (p. 202), from which a-oxyisosuccinic acid is obtained.
Pyruvic acid also condenses readily to benzene derivatives (p. 208). Thus, uvitic
acid, CjHjOi, results when the acid is heated with barium hydrate. Ammonia,
however, produces uvitonic acid (by the decomposition of the imido-pyroracemic
acid, which is first formed) — a pyridine derivative. It readily furnishes condensa-
tion products with hydrocarbons of the benzene series (^Berichte, 14, 1595, and 16,
2071). It also unites with anilines and amido-acids {Berichte, 19, 2554).

It combines with bromine, forming a crystalline, unstable addition product,
CjH^OjBrj. Substitution products result by heating the acid with bromine and
water to 100°; dibrom-pyrumc acid, CBr2H.CO.CO2H, crystalhzes with 2H2O
in large, rhombic plates. It loses its water of crystallization when exposed, and
melts at 89°. Tribrom-pyi-uvic acid,CQx^.CO. CO ^\i or CBr3.C(OH)2.C02H,
is formed by heating a-lactic acid wilh bromine and water. It has two molecules
of water of crystallization, and consists of brilliant leaflets which lose water at 100°,
and then fuse at 90°. When heated with water or ammonia, it breaks up into
bromoform, CHBrg, and oxalic acid.

(2) Propionyl-carboxylic Acid, CjHj.CO.COjH, a-Ketobutyric Acid, is
obtained from propionyl cyanide. It is very similar to pyruvic acid, and can only
be distilled under diminished pressure. Nascent hydrogen converts it into a-oxy-
butyric acid.

(3) Butyryl-carboxylic Acid, CjHj.CO.COjH, is derived from butyryl
cyanide, and boils at 180-185° with slight decomposition. It decomposes readily
into CO 2 and butyric acid.

(4) Trimethyl-Pyroracemic Acid, (CH3)3.C.CO.C02H, results from the
oxidation of pinacoline (p. 210) with potassium permanganate. It melts at 90°
and boils at 185° {Berichte, 23, Ref. 21).

2. ^-Ketonic Adds.

In the /9-ketonic acids the ketone oxygen atom is attached to the
second carbon atom, counting from the carboxyl group forward.
These compounds are very unstable when free and when in the form
of salts. Heat decomposes them into carbon dioxide and ketones.
Their esters, on the other hand, are very stable, can be distilled
without decomposition, and serve for various and innumerable syn-
theses.

334 ORGANIC CHEMISTRY.

The first acid of this class is : —

Aceto-acetic Acid, QHeO, = CH3.CO.CH,.CO,H, /J-Keto-
butyric Acid. We can regard this as acetic acid in which a hydro-
gen atom of methyl is replaced by acetyl, CH3.CO, Or as acetone,
in which carboxyl has taken the place of a hydrogen atom — hence,
the designation acetone carboxylic acid. To obtain the acid, the
esters are saponified in the cold by dilute potash, or the barium salt
is decomposed with sulphuric acid, and the solution shaken wit4i
ether {Berichie, 15, 1781 ; 16, 830). Concentrated over sulphuric
acid, aceto-acetic acid is a thick liquid, strongly acid, and miscible
with water. When heated, it yields carbon dioxide and acetone : —

CH3.CO.CH2.CO2H = CH3.CO.CH3 4- CO2.

Nilrous acid converts it at once into COj and isonitroso-acetone (p. 206). Its
salts are not very stable. It is difficult to obtain them pure, and they sustain
changes similar to those of the acid. Ferric chloride imparts to them, and also to
the esters, a violet-red coloration. Occasionally the sodium or potassium salt is
found in urine [Berichie, 16, 2314).

The stable aceto-acetic esters, CH3.CO.CH2.CO2R, are produced
by the action of metallic sodium upon acetic esters. In this reac-
tion the sodium compounds constitute the first product (Geuther,
1862 ; Frankland and Duppa) : —

CH3 CH3

I -f Na^ = ]

CO.O.G2H5 CO.CHNa.CO.O.CjH^ -\- C^H^.ONa -f H^.

By similar treatment acetic methyl ester yields the sodium com-
pound of methyl aceto-acetic ester (see below). The free esters
result upon treating their sodium compounds with acids. They are
obtained pure by distillation. The aceto-acetic esters are liquids,
dissolving with difficulty in water. They possess an ethereal odor.
They can be distilled without decomposition. Like the free acid,
they break up into carbon dioxide, acetone and alcohols, when
heated with alkalies or acids : —

CH3.CO.CH2.CO2R -J- H^O = CH3.CO.CH, + CO2 -f R.OH.

The formation of aceto-acetic ester is probably such that there first results a so-
dium aceto-acetic ester, CHjNa.COj.CjHj, which in turn reacts with a second
molecule of the acetic ester, a molecule of alcohol, separating at the same time (see
Berichte, 18, 3460) : —

CH3.CO2.C2H5 + CH2Na.CO2.C2H5 = CH3.CO.CHNa.CO2.C2H5 -j- C2H5OH.

It may be, however, that an addition of sodium ethylate to aceto-acetic ester occurs
(Claisen, Berichte, 20, 65I), and the additional product, CH3.C(OC2Hj)2.0Na,
reacts with a second molecule (Claisen, Berichte, 20, 651 ; 21, USS).

KETONIC ACIDS. 335

Sodium also reacts analogously with propionic ester, forming propiopropionic
ester (p. 342).

|8-Aldehydic esters (p. 330) are formed if sodium, or sodium ethylate, acts
upon a mixture of acetic ester (or the ester of any other monocarbonic acid) and
formic ester, whereas, by using a mixture of Icetones and formic esters, aldehyde
ketones are produced. Diketones result if the mixture consists of ketones and
acetic esters (p. 327). The oxalic esters and fatty acid esters yield keton-dicar-
boxylic acids (see oxalacetic acid). All these condensations, are analogous. An
exit of alcohol occurs in each instance. They may well be termed ester-condensa-
tions. It is very probable that in every case the first action consists of the addition
of sodium ethylate {Berichte, 21, II56; 22, 553).

The esters of aceto-acetic acid, contrary to expectation, possess
an acid-like character. They dissolve in alkalies, forming salt-like
compounds in which a hydrogen atom is replaced by metals. All
their reactions indicate that it is the hydrogen of the CHj (attached
to two CO groups) that has the nature of an acid hydrogen.

We here observe an influence of the negative groups CO upon
the hydrogen in union with carbon (in the atomic grouping CO.
CHj.CO) similar to that exercised by the nitro-group in the nitro-
parafEns (p. 107).

It matters not whether the carboxyl group be attached to hydro-
gen, forming the aldehyde or formyl group, or to an alkyl group,
forming the ketone group, or to anoxyalkyl group, forming a
carboxyl-ester group : —

— COH — CO.R — CO.OR

Aldehyde Group. Ketone Group. Carboxyl-ester Group.

The union of two such groups to an atom of carbon gives rise to
six classes of compounds : —

„„ /COH p„ /COR p„ /CO.OR

'^^^2\COH '^'^^XCOR ^"2\C0.0R

Dialdehydes. Diketones. Dicarboxylic Esters.

„„ /CHO p„ /CHO p„ /COR

•-^^XCOR ^"2\C0.0R *-"2\C0.0R

Aldehyde Ketones. Aldehydic Acids. Ketonic Acids.

These are acid in character. Their metallic derivatives are formed
by the replacement of the hydrogen of the CH,- (or CHR-) group.

The formyl group — CHO exercises the most powerful acid influence. Next in
acidity is the ketone group —COR, while the ester group —CO.OR is the most
feeble in its acid nature. Therefore, compounds containing the first group arethe
most acid. The ;8-diketones and the /3-ketonic esters follow in regular succession.
The entrance of an alkyl into the group CH2 greatly diminishes the acid function
of the homologous compounds [Berichte, 22, 1018).

The sodium and potassium compounds are obtained pure from
the aceto-acetic esters by treating the latter with potassium or

336 ORGANIC CHEMISTRY.

sodium, or better, the alcoholates of the latter (in equivalent quan-
tities) : —

C^H^Oa.C.Hj + C.H^.ONa = C^H.NaO^.C.H, + C.H^.OH.

They dissolve readily in water and alcohol, react alkaline and on
exposure decompose. The decomposition is more rapid on boiling
with water (similar to the free aceto-acetic esters) (p. 334)- Di-
lute acids liberate the esters. When the latter are dissolved in
barium hydroxide, corresponding barium compounds are formed,
from which derivatives of the heavy metals are obtained by double
decomposition. "Ammoniacal solutions of metallic salts afford the
same directly from the aceto-esters {Annalen, 188, 268). Consult
Annalen, 201, 143, upon the preparation of the dry sodium com-
pounds.

In quite a number of different reactions aceto-acetic ester conducts itself as if it
possessed the constitution indicated by the formula of its isomeride /3 oxy-crotonic
ester, CH3.C(OH):CH.C02.C2H5. Hence many writers give the ester this con-
stitution (Geuther, Berichte, 21, Ref. 295). The sodium salt is represented by the
formula CH3.C(ONa):CH.C02.C2H5 (A. Michael, Berichte, 21, Refs. S30 and
573). Usually the unsaturated hydroxylform, C(0H):CH2, rearranges itself to the
ketone form (p. 134). Yet, it appears, the reverse sometimes occurs (Berichte, 17,
2621). The two forms may therefore be considered pseudomeric or tautomeric
(Berichte, ig, 730; 20, 651 ; 21, 1084).

Different monovalent radicals can be substituted for the metal in
the sodium aceto-acetic esters. Thus by the action of the alkyl
iodides (or bromides), sodium iodide separating, we get: —

^"\CH.(CH3).C02.C2H3 '-^\CH(C2H,).C02.C2H5.

Methyl Aceto-acetic Ester, Ethyl Aceto-acetic Ester.

In these mono-alkylic aceto-acetic esters another hydrogen atom
can be replaced by sodium, by the action of the metal or sodium
ethylate : —

*-*-'\CNa(CH3).C02.C2H5.
Sodium Methyl Aceto-acetic Ester.

If alkyl iodides be again permitted to act upon these last deriva-
tives, a second alkyl group may be introduced, yielding dialkylic
aceto-acetic esters, e. g. : —

^^\C(CH3)2.C02.C2H, C0( / CH3\ rn C H

Dimethyl Aceto-acetic Ester. ^ClC2H5/ •"-^-'a-'-z^s-

Methyl-ethyl Aceto-acetic Ester.

KETONIC ACIDS. 337

To execute these syntheses, it is not necessary to prepare pure sodium com-
pounds. To the acetoacelic ester dissolved in 10 times its volume of absolute alco-
hol, add an equivalent amount of sodium and then the alkyl iodide, after which
heat is applied. To introduce a second alkyl, employ again an equivalent quantity
of the sodium alcoholate and the alkyl iodide (Anna/en, 192, 153). In some cases
sodium hydroxide may be substituted for sodium ethylate in these syntheses [An-
nalen, 250, 123).

On heating the mono- or dialkylic aceto-acetic esters with alkalies
in dilute aqueous or alcoholic solution, or with barium hydroxide,
they decompose after the manner of aceto-acetic esters (p. 334),
forming ketones (alkylic acetones) (ketone decomposition) : —

C0<C(^k3)H.C0,.C,H, + ^KOH = Co/CHa cjj + C03K,+ C,H,OH,

Methyl Acetone.

CO<cf^k3),CO,.C,n, + ^I^OH = CO <^i^cH3), +C03K,-fC,H,.0H._

Dimethyl Acetone.

At the same time another splitting-off takes place, by which the
alkylic acetic acids, i. e., the higher fatty acids (p. 212) are pro-
duced along with acetic acid (acid decomposition): —

.CH, CH3

CO( + 2KOH = I +CHJCH3).CO,K+ C2H5.OH.

\CH(CH3).C02.C2H5 CO.OK Potassium Propionate.

Potassium Acetate.

Both of these reactions, in vfhich decomposition occurs (the splitting-off of ke-
tone and of acid), usually take place simultaneously. In using dilute potash or
caustic baryta, the ketone-decomposition predominates, whereas, with very concen-
trated alcoholic potash, the same may be asserted in regard to the acid-decompo-
sition (J. Wislicenus, Annalen, igo, 276). The splitting-ofiF of ketone, with elimi-
nation of CO 2, occurs almost exclusively on boiling with sulphuric or hydrochloric
acid (i part acid and 2 parts water). In this case, ketones, or with the dibasic
ketonic acids, ketone monocarboxylic acids are produced (Annalen, 216, 133).
The aceto-acetic esters undergo a decomposition similar to the splitting-off of acid
if they are heated alone to 250°, or with sodium ethylate free from alcohol, when,
instead of acetic acid, we obtain dehydracetic acid, C3H3O4.

The aceto-acetic esters are changed by nascent hydrogen (sodium
amalgam) into the corresponding /3-oxy-acids (of the lactic acid
series) (p. 331) : —
CH3.C0.CH„.C0,.QH, -f H, + H,0 = CH3.CH(0H).CH,.C0,H + C,H,.OH.

Aceto-acetic Ester. ^-Oxybutyric Acid.

They are saponified at the same time. As ketones, they also
unite with CNH, forming oxycyanides (p. 202), which hydrochloric
acid converts into oxydicarboxylic acids : —

CH3.CO CH3-c/g^^ CH3.C(0H).C0,H

I yields I ^ and J

CH,.CO,.C,H5 CH,.CO,.C,H, (iH,.CO,H.

Aceto-acetic Acid. Oxycyanide. Oxypyrotartanc Acid.

338 ORGANIC CHEMISTRY.

In the aceto-acetic esters, the hydrogen of the group CO.CHj.CO can be directly
replaced by chlorine and bromine. The products, like

CHj.CO.CCIj.COj.CjH- and CHj.CO.CCICCHsl.CO^.QHs,
Dichloraceto-acetic Ester. Chlormethylaceto-acetic Ester.

suffer changes with alkalies and acids analogous to those sustained bythe aceto-
acetic esters (see above). Thus, from dichloraceto-acetic esters are obtained
dichloracetone, CHg.CO.CHCI,, and dichloracetic acid, CHClj.COjH ; and from
chlormethylaceto-acetic ester result chlormethyl-ethyl ketone, and a-chlorpropionic
acid, CH3.CHa.CO2H, etc.

All the aceto-acetic esters combine with hydroxylatnine to form esters of the
corresponding |3-isonitroso-fatty acids (p. 214). Nitrous acid changes them to the
isonitroso-derivatives, CH3.C0.C(N.0H).C0jR, which readily break up into
isonitroso- acetone and COj and alcohols (see below). The aceto-acetic esters with
one alcohol radical decompose directly into isonitroso-acetones (p. 206).

The aceto-acetic esters combine with the diazo-compounds (Berichte, 21, 549)
of the benzene series, and are capable of forming various condensation products
(with aldehydes, etc.).

Ethyl Aceto-acetic Ester, CH3.CO.CHj.COj.C2H5 =
CsHioOs, Aceto-acetic Ester, is formed by the action of sodium upon
ethyl acetic ester (p. 254). It also results when acetone-dicarbonic
ester splits off a COjR-group. It is a pleasantly smelling liquid, of
sp. gr. 1.0526 at 20°, boils at 180.8° and distils over with steam.
The ester is only slightly soluble in water, and has a neutral reaction
(that of the methyl ester is acid). Ferric chloride colors it violet.

Boiling alkalies or acids convert the ester into acetone, carbon
dioxide and alcohol.

Preparation of Ethyl Aceto-acetic Ester. — 60 parts metallic sodium are gradu-
ally dissolved in 2000 parts pure ethyl acetic ester. The excess of the latter is dis-
tilled off. On cooling the mass solidifies to a mixture of sodivim aceto-acetic ester
and sodium ethylate. The mass remaining liquid is mixed with acetic acid (50 per
cent.) in slight excess. The oil separated and floating on the surface of the water
is siphoned off, dehydrated with calcium chloride, and fractionated [Annalen, 186,
214 and 213, 137). For the preparation of the dry sodium compound, see Anna-
ten, 201, 143.

The sodium compound, C^H^NaOj.CjHj, crystallizes in long needles, and is
made by heating ethyl acetic ester with sodium ethylate : —

2C2H3O2.C2H5 + C^H^.ONa = CuHgNaOa + 2C2H5.OH.

The copper salt, (CgHg03)2Cu, (Preparation, Berichte, ig, 21), is precipitated in
the form of a bright green powder.

Heated alone or with sodium ethylate, it yields ethyl acetic ester and dehydra-
cetic acid.

The pyron-group is then formed. The action of sulphuric acid causes aceto-
acetic ester to pass into a condensation product, from which the isomeric iso-dehy-
dracetic acid, CgHjO^, splits off. Phosgene, COClj, and copper aceto-acetic ester
yield dimethyl pyron-dicarboxylic ester (Berichte, ig, 22 and 20, 151).

KETONIC ACIDS. 339

Aceto-acetic ester becomes /9-oxybutyric acid under the action
of sodium amalgam. It forms an oxycyanide with CNH, from
which oxypyrotartaric acid is formed (p. 337). PCI5 replaces the
oxvgen of the CO-group by 2 atoms of chlorine. The chloride,
CH3.CCI2. CHj. CO. CI, readily splits off hydrochloric acid and yields
two chlor-crotonic acids (p. 239). Fuming nitric acid changes
it to isonitroso-acetic ester (p. 222).

Chlorine (or sulphuryl chloride, SOjClj) and bromine convert aceto-acetic ester,
or its copper derivative, into a-mono-, and di-substitution products. The CHj-group
is first attacked {Berichte, 21, Ref. 831 ; 22, Ref. 680; Annalen, 253, 168).

a-Chlor-aceto-acetic Ester, CHj.CO.CHCl.COj.C^Hj, is an oil with a very
penetrating odor. It boils at 193°. In the action of chlorine, the y-chloraceto-
acetic Ester, CH2CkCO.CH2.CO2.C2H5, is said to be produced simuhaneously
with the a-product. It boils at 188°. It yields citric acid with potassium cyanide
(Berichte, 22, Ref. 255).

a-Brom-aceto-acetic Ester, CHg.CO.CHBr.COj.CjHj, (see above), is an oil
witli piercing odor. It boils at 2io°-2i5°. It attacks the eyes strongly.

a-Dichloraceto-acetic Ester, CH3.CO.CCI2.CO2.C2H5, is a pungent-smelling
liquid, boiling at 205°. Heated with HCl it decomposes into a-dichloracetone,
CH3.CO.CHCI2, alcohol and COj ; with alkalies it yields acetic and dichloracetic
acids {^Berichte, 16, 1553).

a-Iodo aceto-acetic Ester, CH3.CO.CHI.CO2.C2H5, is produced when
iodine acts upon copper aceto-acetic ester. It is a green-colored oil. It forms a
pyrazolon-derivative with phenylhydrazine (253, 19+).

Isonitroso-aceto-acetic Ester, CH3.CO.C(N.OH).C02.C2H5, is formed on
dissolving ethyl aceto-acetate in dilute potash, adding a solution of potassium ni-
trite (l molecule NOjK) and acidifying with dilute sulphuric acid (^Berichte, 15,
1326). Shining leaflets or prisms readily soluble in alcohol or ether; they melt
at 53°, and decompose when heated (p. 338). It has an acid reaction, dissolves
in alkalies with a yellow color and is colored an intense red by phenol and sul-
phuric acid (p. 107). Hydroxylamine forms di-iso nitroso-butyric ester, CHg.
C(N.OH).C(N.OH).C02.C2H5, with it {Berichte, 17, 821).

Ammonia converts aceto-acetic ester into paramido-aceto-acetic ester, C5H;iN02,
which may be regarded either as /3 Imido butyric Ester, CH3.C(NH).CH2.
CO2.C2H5, or as ^-Amidocrotonic Ester, CH3.C(NH2):CH.CO.C2H5 {Anna-
len, 226, 294). It crystallizes in bright leaflets, melts at 34°, and boils at 210°-
215°, with partial decomposition. When distilled, it passes into a luHdone deriva-
tive {Berichte, 20, 445), while it forms hydrocoUidine dicarboxylic ester with alde-
hyde.

Aceto-acetic ester also unites with methylamine and diethlyamine {Berichte, 18,
619). With aniline it yields phenyl-imido butyric acid (see this), which easily
passes over into quinoline derivatives. With amidines, pyrimidine compounds re-
sult {Berichte, 18, 759). Acetamide and aceto-acetic ester form aceto-/3-imido-
butyric ester {Berichte, 18, Ref 141). Pyrazolon-derivatives are formed by union
with phenylhydrazine (see these).

Nitrous acid converts /3-imidobutyric ester into imido-isonitroso-butyric ester,
CH3.C(NH).C(N.OH).C02.C2H5. This is a yellow oil. When reduced with
zinc dust, it condenses to dimethyl-pyrrol-dicarboxylic ester {Berichte, 17, 1638).
Zinc chloride condenses it to a ketine derivative (see Ketines).

34° ORGANIC CHEMISTRY.

Methyl Acetoacetic Ester, CHj.CO.CH^.CO^.CHj, is formed from methyl
acetate (p. 338). It boils at 170°, and is colored a dark cherry-red by ferric
chloride. Otherwise it is perfectly similar to the ethyl ester.

Methyl Ethyl Aceto-acetic Ester,CO(' (-,,(4jj sjj CO C H

= QHijOs (p. 336), (a-aceto-propionic ester). This boils at 186°
and has a specific gravity of i.oi at 12°. Potash readily decom-
poses it into methyl acetone, carbon dioxide and alcohol. By the
acid-decomposition it yields propionic acid. Free methyl aceto-
acetic acid, obtained by saponification of the ester with alkalies in
the cold, is very similar to aceto-acetic acid (p. 336).

Dimethyl Aceto-acetic' Ester, CO([^f^,p''rT > ^^ r w ^= CgHj^O,, is an

oil, nearly insoluble in water, of sp. gravity 0.991 at 16°. It boils at 190°. Boil-
ing aqueous potash does not affect it. Alcoholic potash, however, or baryta water,
changes it to dimethyl acetone, carbon dioxide, and alcohol. By the acid-decom-
position it yields isobutyric acid, (CH3)2.CH.C02H. "Vae-free acid is crystalline,
but very unstable. /CH

Ethyl Aceto-acetic Ester, CO; rYtir h "i CO C H ' '^ sparingly soluble in
water. It boils at 195°. Its specific gravity equals 0.998 at 6°- Ferric chloride
colors it blue. Boiled with aqueous potash, it decomposes into ethylacetone,
carbon dioxide, and alcohol. In the acid- decomposition it forms normal butyric
acid. /CH

Diethyl Aceto-acetic Ester, CO.^ p, J „ , ^^ „ „ ':= CjjHjjOj, is insolu-

\U(^1^2rl5)2.^^U2C2rl5

ble in water, boils at 210-212°, and has a specific gravity ato° of 0.974. Aqueous
potash has no effect upon it, while with alcoholic potash or baryta water it yields
diethyl ketone, CH3.CO.CH(C2H5)2. By the acid-decompasition (with sodium
ethylate) diethylacetic acid results. The free diethyl-aceto-acetic acid is liquid,
and when distilled, yields COj and diethyl acetone.

Methyl-ethyl Aceto acetic Ester, CO^ CfCH MT H ^ CO C H ^^ ^^\f^v
boils at 198°. By decomposition it furnishes methyl-ethyl acetone and methyl-
ethyl acetic acid (p. 229).

For other mixed alkyl aceto-acetic esters consult Annalen, 226, 206.

Allyl Aceto-acetic Ester, CO^ „[,?(-. tt ■, /-.(-, p cj ^= CgHjjOj, is obtained

by the action of allyl iodide upon sodium aceto-acetic ester. It boils at 206°; its
specific gravity is 0.982 at 17.5°. Ferric chloride gives a carmine-red coloration.
When it decomposes, allyl acetone and allyl acetic acid are produced (p. 241).
Sodium amalgam changes it into allyloxybutyric acid. By the addition of more
allyl, we obtain — • //-.tt

Diallyl aceto-acetic Ester, COc „,„3 . „„ „ tj- which boils at 206°,

\C(,C3tl5)2.C02.C2H5,

and decomposes into diallyl acetone and diallyl acetic acid.

By the action of propyl iodide, isopropyl iodide, isobutyl iodide, amyl iodide,

benzyl chloride, CgH5.CH2CI, etc., higher aceto-acetic esters have been formed,

from which, by decomposition, higher ketones and fatty acids resulted, and were

converted into higher oxy-acids by the addition of Hj.

The following is an a-7-kelonic ester : — /CCi CH

Acetonyl-aceto-acetic Ester, CH3.CO.CH2.CH(^^X r ' , is produced

KETONIC ACIDS. 34 1

by the action of chloracetone, CHj.CO.CHjCl, upon aceto-acetic ester. It forms
pyrotritaric ester {Berickte, 17, 2759) with fuming hydrochloric acid. On heating
the ester with water to l6o° C. acetonyl acetone results.

By the action of chlorcyanogen upon sodium methyl aceto-acetic ester the follow-
ing derivatives are produced : —

Methyl Cyan-acetoacetic Ester, CH3.CO.CH(CN).C02.CH3. This can
be prepared from methyl cyanacetic ester when acetyl chloride acts upon its sodium
compound {Berichte, 21, Ref. 187 ; 22, Ref. 207). It is crystalline, readily solu-
ble in alcohol and ether, and meilts at 46°. Its reaction is acid. Its salts crys-
tallize well.

Ethyl Cyan-acetoacetic Ester, CH3.CO.CH(CN).C02.C2H5, from ethyl
cyanacetic ester, melts at 26°.

Methyl and ethylaceto-acetic esters yield corresponding cyanogen products, CHj.
CO.C(CN)R.C02.C2H5. These are insoluble in alkalies {Berichte, 22, Ref. 407).

The hydrogen in the aceto-acetic esters may also be replaced by
acid radicals, by letting the acid chlorides act on the sodium com-
pounds, suspended in ether. Thus arise the diketon-monocarboxylic
esters. Acetyl chloride forms : —

Acetyl Aceto-acetic Ester, C2H30.CH(C2H30).C02.CjH5 or Diaceto-acetic

Ester.pjT^'pQ ^CH.C02.CjH5. It boils with partial decomposition at 210°, and

is broken up by water, even at ordinary temperatures, into acetic acid, aceto-acetic
ester and COj (Annalen, 226, 210). Sodium ethylate displaces an acetyl group in it,

C T-T 0\
forming aceto-acetic ester and sodium aceto-acetic ester : p'-u^n / CH.COj.CjHj -(-

C2H5.0Na= C2H3O.CHNa.CO2.C2H5 4- C2H3O.O.C2H5. ^Acetyl-methyl-aceto-
acetic ester and acetyl-ethyl-aceto-acetic ester, (C2H30)2C(CjH5).C02.C2H5, are
produced in an analogous manner.

CH CO \
Benzoyl aceto-acetic Ester,^ t|' p^-, /CH.C02.C2H5,obtained from aceto-
acetic ester by benzoyl chloride, breaks up, when boiled with sulphuric acid, into
benzoyl acetone, CH'j.CO.CHj.CO.CgH^ {Berichte, z.^, 2239), and CO2.

The following is a monobasic Diketonic Acid :

Aceto-pyroracemic Acid, CjHgO^ = CH3.
Oxalic Acid. Its ethyl ester results when sodium ethylate acts upon acetone and
oxalic ester. It boils at 214° {Berichte, 20, 2189). Ferric chloride imparts a dark
red color to it. Copper acetate precipitates the green copper compound (C5H504)2
from its alcoholic solution. The acid, liberated from the ester, condenses quite
readilv to symmetrical oxytoluic acid (Berichte, 22, 3271). As a /3-diketone com-
pound (CO.CHg. CO), acetone-oxahc ester manifests all the reactions peculiar to
this class.

Acetophenone, CeHj.CO.CHs, by treatment analogous to that
just described above, passes into the ester of benzoyl pyroracemic
acid, C6H5.CO.CH2.CO.CO2H (see this).

342 ORGANIC CHEMISTRY.

Acid residues can also be introduced into the aceto-acetic esters,
by allowing esters of substituted fatty acids to act upon the sodium
compounds. The esters of the ketone dicarboxylic acids are ob-
tained in this way. Chlorformic ester produces

Aceto-malonic Ester, CHs.CO.CH^^^q^-^'^^ Chlor-
acetic ester, CH2CI.CO2.R, yields ynxj rn v>

Aceto-succinic Ester, CH3.C0.CH( ^q^-^'^''-^. These

dibasic ketonic acids will be discussed after the oxy-acids. Di-

CH3.CO.CH.CO2.C2H5
acetyl succinic Ester, | , a rather remark-

CH3.CO.CH.CO.,.QH5
able body, produced by the action of iodine upon sodium aceto-
acetic ester, properly belongs in the same section.

Sodium also facilitates the conversion of propionic ester into a-propionyl-propio-
nic ester [Berichte, 20, 1320 and Annalen 239, 386) : —

CHj.CHNa CH3CH.CO.CH2.CH3

I -f CjH^.O.OC.CH^.CHjz^ I

CO^.C^H, io^.C^H. + C^Hj.ONa.

2 Molecules Propionic Ester. a-Propionyl-propionic Ester.

On the other hand normal butyric ester, isobutyric ester and isovaleric ester, when
acted upon by sodium, do not yield analogous compounds, but the oxy-alkyl de-
rivatives of higher fat-acids [Berichte, 22, Ref. 22). The action of ferric chloride
upon fatty acid chlorides is a common synthetic method for the preparation of
higher /3-ketonic acid esters. In this reaction the chlorides of the ketones are first

formed: 2C2H5.CO.CI = C^Hj.CO.Ch/^qS^j + HCl. When treated with

water they split off CO2, and become ketones (p. 200). With alcohol they are
converted into esters of the ketonic acids (Hamonet, Berichte, 22, Ref 766) : —

C2H,.CO.CH/^g3^,+ C2H,.OH = C2H,.CO.Ch/^^^3(,^jj^ + HCl.

a-Propionyl-propionic Acid.

a-Propionyl-propionic Ester, CjHj.CO.CH^^PQ 'p „ , prepared by both

methods, is an agreeably smelling liquid, boiling at 199° ; its specific gravity at 0°
is 0.995. Sodium alcoholate and ethyl iodide do not convert it into ethyl propi-
onyl-propionic ester, but into the decomposition products of the latter — propionic
ester and methyl ethyl acetic ester. Sodium amalgam converts it into the corres-
ponding oxy-acid, which passes into methyl propyl acetic acid by reduction (p. 230).

CHj.CO.CH.COj.CjHj
Succinyl-succinic Ester, CijH.jOg = | | ,

CjH5.CO2.CH. CO.CH2
may be similarly obtained from succifiic ethyl ester by the action of sodium or so-
dium alcoholate. This new coihpound is doubtless a quino-tetrahydro-dicarboxy-
lic ester, and will be considered mw^sx the benzene derivatives.

KETONIC ACIDS. 343

3. y-Keionic Adds.

These have the ketone oxygen atom attached to the third carbon
atom from the carboxyl group (p. 331) and are distinguished from
the acids of the /J-variety by the fact that they are stable in a free
condition even when heated. By the addition of two hydrogen
atoms they yield ;'-oxy-acids, which immediately pass into lactones
(see these).

When distilled, the 7-ketonic acids split off water and pass into unsaturated
lactones [Berichte, 18, 2263). This transposition may be explained by assuming
that the tautomeric form of the y-lactone is to be ascribed to the 7 ketone acids
(Annalen, 226, 225) : —

CH3.CO.CH2.CH2 CH3.C(OH).CH2.CH2 CH^.CCH.CH^
I or I I yields I I

COOH O CO O CO.

Laevulinic Acid. Angelica Acetone.

/3-Aceto-propionic Acid, CsHgOs = CH3. CO. CH^. CH^. CO^H,
Laevulinic Acid, ^-Ketovaleric Acid. This is isomeric with methyl
aceto-acetic acid, which may be designated a-aceto-propionic acid
(p. 340). It is obtained from aceto-succinic ester (p. 342) on
boiling with hydrochloric acid or baryta water, and from cane sugar,
Isevulose, starch, and apparently from all the carbohydrates {Ber-
ichte, 19, 707) on boiling them with dilute hydrochloric or sulphuric
acid.

Preparation. — Heat 500 grs. of sugar dissolved in I litre of water with 250
grs. of crude concentrated hydrochloric acid until the separation of brown humus
substances ceases. The solution is then concentrated, repeatedly extracted with
ether, and the Isevulinic acid, remaining after the evaporation of the ethereal solu-
tion, is purified by distillation in a vacuum. A yield of about 8 per cent, of acid
is obtained in this way (^Annalen, 227, 99).

A more advantageous method is to boil starch with hydrochloric acid {Berichte,
20, 1775). The yield of acid is about 13 per cent. It is obtained commercially
by heating cane sugar with dilute hydrochloric acid [Berichte, 19, 2572).

Laevulinic acid dissolves very readily in water, alcohol and
ether, and crystallizes in scales, melting at 33.5°. The acid boils
with slight decomposition at 239°. Traces of moisture lower the
melting point. The molecular refractions of the free acid and its
esters confirm the idea of its being a ketonic acid (p. 60).

In accordance with this view it yields y-isonitrosovaleric acid (p. 228) with
hydroxylamine. It unites with phenylhydrazine acetate to form phenylhydrazine-
Isevulinic acid, C5H5.N2H:C{CH3).CH2.CHj.C02H. This passes into an anhy-
dride, CiiHijNjO, when heated to 166° [Berichte, 22, Ref. 673). It melts at 108".
The hydrazone yields y-amidovaleric acid by reduction (p. 319).

The calcium salt, (C5H,03)2Ca -f 2H2O, forms delicate needles; the barium
salt is a gummy mass. The silver salt is a characteristic, crystalline precipitate,
dissolving in water with difficulty, Ta& methyl ester, C5H,(CH3)03, boils at
191°, the ethyl ester at 200°.

344 ORGANIC CHEMISTRY.

When heated to 150-200° with hydriodic acid and phosphorus,
lasvulinic acid is changed to normal valeric acid. By the action of
sodium amalgam sodium ;'-oxyvalerate is produced. The acid
liberated from this becomes valerolactone. Dilute nitric acid con-
verts laevulinic acid (analogous to the oxidation of ketones, p. 203)
into acetic and malonic acid and again into succinic acid and car-
bon dioxide.

Lgevulinic acid unites with potassium cyanide, forming the lactbne cyanide,
CH3.C(CN).CH2.CH2

I I , from which a-methyl-glutaric acid is obtained by hydro-

O CO

chloric acid {Berichte, ig, 3269).

Two angelica lactones, CjHgOj (a and ;3), are produced on distilling laevulinic
acid. Water separates at the same time. The a-derivative yields /J-bromlsevu-
linic acid by the addition of hydrobromic acid.

;8-Bromlsevulinic Acid, CHj.CO.CHBr.CH^.COjH, obtained from the
lactone (^see above), melts at 59°. Its ethyl ester is produced in the bromination of
Isevulinic ester, and boils at 240°. It yields diaceto glutaric ester [Berichte, 19,
47) with sodacetoacetic ester. Warming with sodium hydroxide converts the
/3-bromlaevulinic acid into hydroxy-l^vulinic acid and aceto-acrylic acid (see below)
{^Berichte, 20, 425). Aniline converts brom- Isevulinic acid into dimethyl-indol, as
all compounds with the group — CO.CHBr — react analogously [Berichte, 21, 3360).

/3-Aceto.butyric Acid, CHj.CO.Ch/^J^" ^q j^ = C^H^f)^, ^methyl

aceto-propionic acid, is obtained from a-methyl aceto-succinic ester (p. 342). It
boils at 242° and becomes crystalline at — 12°. The ethyl ester boils near 205°.
The isomeric — ^tt ^^ rvf \

/3-Aceto-isobutyric acid, ^"^'■^^■^^■'ycn.CO^n=:C^^if)^,a-mt\hy\-

Ijevulinic acid, from ;3-methyl aceto-succinic ester, boils at 248°. Its ethyl ester
boils at 207°.

Nitric acid oxidizes both acids to CO 2 and methyl succinic acid (pyrotartaric
acid). Consult Berichte, 23, 622 upon the lactone formation of the alkyl-lsevu-
linic acids.

6'Ketonic Acid.

7-Aceto-butyric Acid, CHj.CO.CH^.CHj.CHj.CO^H = C^Yiyf)^, is ob-
tained from the ester of aceto-glutaric acid (p. 341) by the withdrawal of C02.
It melts at 13° and boils at 275°. Sodium amalgam converts it into a salt of
(S-oxycaproic acid, which yields a rf-lactone [Annalen, 216, 1 27).

UNSATURATED KETONIC ACIDS.

^-Aceto-acrylic Acid, CHj.CO.CHiCH.CGjH, is derived from |3-bromlsevu-
linic acid (see above) upon digestion with a soda solution. It crystallizes from
alcohol in brilliant needles melting at 125° C. It combines with phenylhydrazine
{Berichte, 21, 2937) and with brornine, forming in the latter case dibrom-lsevu-
linic acid. Ammonia converts this into tetramethyl pyrazine (dimethyl ketine)
{Berichte, 20, 426).

;8-Trichlor-aceto-acrylic Acid, CCIj.CO.CHiCH.CO^H, is very probably
Trichlorphenomalic Acid. This is obtained from benzene by the action of potas-

ALCOHOL- OR OXY-ACIDS^ 345

slum chlorate and sulphuric acid (Annalen, 223, 170). It crystallizes from water
in shining leaflets, melting at 131°. It breaks up into chloroform and maleic acid
when boiled with barium hydroxide. /CO CHj

Ethidene Aceto-acetic Acid, CHj.CHiC _^ . The ethyl ester re-

\CO2H
suits from the action of hydrochloric acid upon aldehyde and aceto-acetic ester.
A liquid with penetrating odor, and boiling at 2H° Caustic potash decomposes
it (Annalen, 218, 172).

A series of homologous acids, CnHjn— iO,, has been prepared from the bromi-
nated alkyl aceto-acetic esters by the action of alcoholic potash, or by heating them
alone or with water. These have been called pentinic, tetrinic acids, etc., etc.
(Demarcay).

Tetrinic Acid melts at 189° and boils at 262° It takes on a violet color upon
the addition of ferric chloride.

Pentinic AcidmA'a at 126.5° ^'^^ 's colored cherry-red by ferric chloride.

The two compounds appear, however, not to be carboxylic acids, but are more

,C0— O
properly ketolactones of the formula R.CH:^ | (see Berichte, 21, 2603 ;

22, 243). , ^CO— CH2

The Oxy tetrinic Acid, CjH^Oj, from tetrinic acid, is identical with mesaconic
acid (Berichte, 21, Ref. 180).

The sulpho-carboxylic acids are analogues of the keton-carboxylic acids. They
form a-, /3-, and y-derivalives : —

C5H5.SO2.CO2H C2H5.SO2.CH2.CO2H Cj^j.SO^.CH^.CH^.CO.H.
Phenyl sulpho-formic Ethyl sulpho-acetic Acid. Ethyl sulpho-propionic Acid.

Acid.

These are prepared by the action of the sulphinates, R.SO^Na, upon the esters
of chlorfatty acids, e. g., chlorformic ester, CICO^R, chloracetic ester, etc. {Berichte,
21, 89, 992).

ALCOHOL- OR OXY-ACIDS.

^""^-XCO-.H.

Acids of this series, with the empirical formula, CnHj^Os, show
a twofold character in their entire deportment. Since they contain
a carboxylic group, they are monobasic acids ,with all the attaching
properties and transpositions of the latter ; the OH-group linked to
the radical bestows upon them all the properties of the monohydric
alcohols. They may, therefore, be designated alcohol acids (corre-
sponding'to the ketonic acids, p. 331, and the aldehyde acids, p.
329). They were formerly called divalent or dihydric {diatomic')
acids, as they contained two hydroxyl groups (an alcoholic and an
acid) and could be obtained by oxidizing the dihydric alcohols
(p. 297). At present they are mostly termed oxy- or hydroxy-fatty
29

346 ORGANIC CHEMISTRY.

acids, because of their origin from the fatty-acids by the replace-
ment of a hydrogen atom by OH : —

C.H^.CO.H and C^H./^J^h"

Propionic Acid. Oxypropionic Acid.

This view of them is especially well adapted for the nomenclature
of the acids (p. 348).

The following are the chief methods of producing the oxy-
acids : —

1. The transposition of the mono-halogen fatty acids with silver
oxide, boiling alkalies, or even water : —

CHjCl.CO^H + KOH = CH /°Q ^ + KCl.
Monochloracetic Acid. Oxy-acetic Acid.

The conditions of the reaction are perfectly similar to those observed in the
conversion of the alkylogens into alcohols (p. 119). The a-derivatives yield
a-oxy-acids ; the ^-derivatives are occasionally changed to unsaturated acids by the
splitting-off of a haloid acid (p. 235), while the y-compounds form 7-oxy-acids,
which subsequently pass into lactones. y-Halogen acids are converted directly
into lactones by the. alkaline carbonates.

The oxy-acids can be reconverted into fatty acids by heating
them with hydriodic acid (p. 94) : —

CH2(OH).C02H -f 2HI = CHj.COjH + H^O + I^,

or are first changed to monobrom-acids with hydrobromic acid : —
CH2(OH).C02H + HBr = CH^Br.CO^H + H^O,

and the product reduced with nascent hydrogen.

2. Some fatty acids have OH directly introduced into them.
This is accomplished by oxidizing them with KMnOj in alkaline
solution : —

(CH3),.CH.C02H -f O = (CH3),.C(0H)C0,H.

Isobutyric Acid. a-Oxyisobutyric Acid.

Only acids containing the tertiary group CH (a so-called tertiary H-atom) are
adapted to this kind of transposition [Annalen, 208, 60, 220, 56). Nitric acid
effects the same as MnO^K {Berichte, 14, 1782; 15, 2318).

3. The action of nascent hydrogen (sodium amalgam, zinc and
hydrochloric acid) upon the ketonic acids and their esters (p. 331): —

CH3.CO.CO2H -f Hj = CH3.CH(OH).C02H.
Racemic Acid. a-Oxypropionic Acid.

4. By the action of nitrous acid upon amido-acids : —
CH3(NH J.COjH + NO2H = CH2(OH).C03H + N^ -f H^O.

Amido-Acetic Acid. Oxyacetic Acid.

ALCOHOL- OR OXY-ACIDS. 347

This reaction is perfectly similar to that observed in the conver-
sion of aniines into alcohols (p. i6i). The intermediate products
are the diazofatty acids, and on boiling them with water or dilute
acids oxyacids result (see these).

5. Careful oxidation of the glycols with dilute nitric acid or
platinum sponge : —

CH^.OH CH^.OH

I + O2 = 1 + H2O,

CH^.OH CO.OH

Glycol. GlycoUic Acid.

CH3.CH.OH CH3.CH.OH

I -fO,= I -(-H3O.

CH^.OH CO.OH.

a-Propylene Glycol. a-Lactic Acid.

6. By allowing hydrocyanic acid and hydrochloric acid to act
u'pon the aldehydes and ketones. At first oxycyanides are pro-
duced (p. 202), after which hydrochloric acid changes the cyanogen
group into carboxyl : —

CH3.CHO + NCH = CH3.Ch/°^ and
CH3.CH<'g^ +. 2H,0 = CH3.Ch/0^^jj + NH3.

a-Oxypropionic Acid.

In preparing the oxycyanides, the aldehydes or ketones are heated under pres-
.sure, with the equivalent amount of hydrocyanic acid (from 20-30 per cent.). Or
we can add pulverized potassium cyanide to the ethereal solution of the ketone,
and follow it with the gradual addition of concentrated hydrochloric acid {^Berichte,
14, 1965; 15, 2318). The concentrated hydrochloric acid, changes the cyanides
to acids, the amides of the acids being at first formed in the cold, but on boiling
with more dilute acid they sustain further change to acids. Sometimes the change
occurs more readily by heating with a little dilute sulphuric acid.

The glycol chlorhydrins (p. 302) undergo a like alteration
through the action of potassium cyanide and acids : —

CH2.(0H).CH2C1 -I- CNK = CH2(OH).CH2.CN + KCI and
CH2.(OH).CH2CN -f 2H20= CH2(OH).CH2.C02H + NH3.

jS-OxypropiQnic Acid.

7. A method of ready applicability in the synthesis of oxyacids
consists in permitting zinc and alkyl iodides to act upon diethyl
oxalic ester (Frankland and Duppa). This reaction is like that in
the formation of tertiary alcohols from the acid chlorides by means
of zinc ethyl, or of the secondary alcohols from formic esters (p. 121)
— I and 2 alkyl groups are introduced into one carboxyl group
{Annalen, 185, 184) : —

CO.O.C.Hs C(CH3)2.0H CH3 OH

I yields I = /C,

CO.O.C.H, io.O.C^H, CH3/ ^CO,,C,H,

Oxalic Ester. Dimethyl-oxalic Ester.

348 ORGANIC CHEMISTRY.

If we employ two alkyl iodides two different alkyls may be intro-
duced.

The acids obtained, as indicated, are named in accordance with
their derivation from oxalic acid, but it would be more correct to
view them as derivatives of oxy-acetic acid or glycoUic acid,
CH2(OH).C02H, and designate, e. g., dimethyl-oxalic acid, as
dimethyl-oxyacetic acid.

8. The fatty acids are formed from alkyl malonic acids, CRR'(C02H)2,by the
withdrawal of one carboxyl group (p. 2iz), and the oxy-fatty acids are obtained
in a similar manner from alkyl oxymalonic acids or tartronic acids : —

CR(0H)<'^°2j[^ = CRH(0H).C02H.
Alkyl-tartronic Acid. Alkyl-oxy-acetic Acid,

The tartronic compounds are synthetically prepared from malonic acid esters,

/CO C H
c. g., CH„<' rri^ r^ 1^^ ' ^J ^^^^ introducing the alkyl group (see malonic acid),

then replacing the second hydrogen of CHj by chlorine, and finally saponifying
the alkylic monochlor-malonic ester with baryta {Berichie, 14, 619). The suc-
cessive transformations correspond to the formulas ; — •

"""^XCO^.CHj ^"'^^XCOj.CHj ^"^^'xCOi.CHj and UK(Uhl)^(,Q^jj.

The possible isomerides of the dihydric acids are best derived
from their corresponding monobasic acids, by replacing a hydrogen
atom in the latter by OH.

Only one oxy-acid can be derived from acetic acid, viz., glycollic

acid, CH2.OH.COOH. From propionic acid, CHg.CHj.CO^H,

we can obtain two oxy-acids. Five isomerides agree with the for-

/ OTT
mula, CjHjOs = CsHe^^ pQ tt ; three of them are derived from

normal butyric acid, CH3.CH,.CH2.C02.H, and two from isobu-
tyric acid, (CH3)2CH.C02H, etc.

The above compounds are named like the substituted fatty acids
(p. 223), i. e., as a-, /?-, -;', etc., oxy-acids: —

CH3.CH(OH).C02H CH2(OH).CH2.C02H

a-Oxypropionic Acid. |8-Oxypropionic Acid.

CHj^OHj.CHj.CHj.COjH

y-Oxybutyric Acid.

CH:>C(0H).C02H CH2(ol')>CH.C02H.

a-Oxyisobutyric Acid. |3-0xyisobutyric Acid.

The a- and /3-oxy-acids exist free, while the ^-acids are only
known in their salts and acids. When liberated from the latter
they immediately give up a molecule of water and pass into their

ALCOHOL- OR OXY-ACIDS. 349

anhydrides, the lactones. Various other peculiarities distinguish
them (p. 350).

The oxy-fatty acids containing one OH group are, in consequence,
more readily soluble in water, and less soluble in ether than the
parent acids (p. 297). They are less volatile, and as a general thing,
cannot be distilled without undergoing a change.

Their chemical properties fully accord with their structure, by
which they are both acids and alcohols. The acid hydrogen (of
the carboxyl group) can be easily replaced by metals and hydro-
carbon residues, thus giving rise to normal salts and esters : —

CHj.OH CH2.OH

and I
O.OK

i

The remaining OH-group deports itself like that of the alcohols.
Alkali metals and alkyls may replace its hydrogen. Acid radicals
and NO2 are substituted for it by the action of chlorides of mono-
basic acid radicals (like C2H3O.CI), and a mixture of concentrated
nitric and sulphuric acids : —

„ jj /O.C2H3O ^ (. jj /O.NO^

Aceto-lactic Acid. Nitro-lactic Acid,

Bo^h these reactions are characteristic of the hydroxyl groups of
the alcohols (p. 302).

PCI5 replaces the two hydroxyl groups by chlorine : —

GlycoUic Acid. Glycolyl Chloride, or

Chloracetyl Cliloride.

The chlorine in union with CO is very reactive with water and
alcohols, yielding free acids and their esters j in the case cited,
monochlor-acetic acid, CHjCLCO^H, and its esters result. The
remaining chlorine atom is, on the contrary, firmly united, as in
ethyl chloride.

The various esters of the dihydric acids exhibit similar rela-
tions : —

rvi /OH f.rr /O.C2H5 CH /O-C^Hs

Etliyl GlycoUic Ethyl GlycoUic Ethyl Etho-glycoUic

Ester. Acid. Ester.

Alkalies cause the alkyl combined with CO^ to separate, forming
ethyl glycollic acid, CH2 ^q |j *-

See Berichte, 15, 162, upon the formation of esters of the oxy-
acids.

35° ORGANIC CHEMISTRY.

In the preceding transpositions all the oxy-acids react similarly,
but in those following they exhibit variations influenced by the
position of the OH group.

Their varying behavior when oxidized is characteristic, especially
when chromic acid is employed as the oxidizing agent (p. 203).

The primary oxy-acids, containing the primary alcohol group,
GH2.OH, may have the latter converted into aldehyde, and car-
boxyl groups (p. 117), and the products will then be aldehyde-acids
and dicarboxylic acids. Thus, from glycoUic acid are derived
glyoxylic and oxalic acids : —

CH^.OH

CHO

yields |

CO.OH

1

CO.OH

CO.OH

CO.OH.

Glycollic Acid.

Glj-oxylic Acid.

Oxalic Acid.

The secondary oxy-acids, with the secondary alcoholic group,
>CH.OH, can yield ketones, which, however, pass very readily
into other compounds (p. 333). The a-oxy-acids, too, lose carboxyl
when boiled with a chromic acid mixture. In them the CO^H and
OH groups are attached to one carbon atom. Should the latter be
linked to two hydrocarbon residues, ketones and carbon dioxide are
produced : —

CH3/^(°^^)-^°2^ + O = CH3/CO -t- CO, + H,0 ;
a-Oxyisobutyric AcidV Acetone.

whereas, if it be in combination with only one such group, alde-
hydes are first formed : —

CH3.CH(OH).C02H + O = CH3.CHO + CO^ + H^O;
a-Oxypropionic Acid. Aldehyde.

and these can then be further oxidized to acids. '

The a-oxyacids undergo a like decomposition when heated with dilute sulphuric
or hydrochloric acid (or by action of concentrated HjSO^). Their carboxyl group
is removed as formic acid (when concentrated HjSO^ is employed, CO and HjO
are the products) : —

(CH3)2C(OH).C02H + HjO = (CH3)2CO + HCO^H,
CH3.CH(OH).C02H + H2O = CH3.CHO -f HCOjH.

Another alteration is sustained by the a-oxy-acids at the same time ; it, however,
does not extend far. Water is eliminated and unsaturated acids are produced.
This change is easily effected when PCI3 is allowed to act on the esters of a-oxy-
acids (p. 235).

When the |3-oxy-acids are heated alone- or with acids, water is withdrawn and
unsaturated acids are almost the sole products (p. 346) : —

CH2(OH).CH2.C02H = CH^iCH.CO^H + H^O.

jS-Oxypropiojiic Acid. Acrylic Acid.

ALCOHOL- OR OXY-ACIDS. 35 1

Anhydrides of the Oxy- acids. — The anhydrides of the oxy-acids may be pro-
duced in three ways. If two molecules of the acids unite so that the water can be
withdrawn from the carboxyl groups, the true or real acid anhydrides are formed.
These are perfectly analogous to the anhydrides of the fatty acids (p. 248). If the
water should arise from the alcohol hydroxyls, then the products are alcohol anhy-
drides or anhydridic acids : —

CH^.OHCHj.OH CH2— O— CHj

II ^°<i i i

CO— O— CO CO.OH CO.OH.

Acid Anhydride, Alcohol Anhydride,

GlycoUic Anhydride. DiglycolUc Acid.

The acid anhydrides of the oxy-fatty-acids have not yet been prepared. The
alcohol anhydrides, like diglycoUic acid, correspond perfectly to the ethers and
sometimes appear on heating the oxy-acids. As a general thing they are prepared
according to the same methods as the ethers of the alcohols. Thus diglycoUic acid
(and some glycoUic acid) is obtained from monochloracetic acid, CH^Cl.COjH, by
the action of bases (lime water or lead oxide) ; further, dilactic acid (its esters) is
made from a-chlorpropionic ester and sodium lactic ester : —

CH3.CHCI CH(ONa).CH. CH,.CH— O— CH.CH,

I + I ' ' ' = ^ I

COjR CO2R COjR CO2R

a-Chlorpropionic Sodium Lactic Dilactic Ester.

Ester. Ester.

These ether acids (anhydridic acids), like the alcohol ethers, break up into
oxy-acids on heating them with hydrochloric acid to 100°.

In the third class of anhydrides, the ester anhydrides, the reaction is between
the hydroxyl groups of carboxyl and the alcohol (p. 251). Should two molecules
of the oxy-acid react we may have the single and double ester formation. Thus,
glycoUic acid forms a first and second anhydride: —

CHj.OH CO.OH CHj— O— CO CH^— O— CO

1 + I yield I - I and I | .
CO.OH CH^.OH CO.OH CH^.OH CO— O — CH^

2 Molecules GlycoUic Acid. ist Anhydride 2d Anhydride

GlycoUic Anhydride. Glycolide.

From lactic acid (aoxy-propionic acid), CjHgOj, we get lactic anhydride,
CgHjjOj, and the so-called Lactide, CgHjO^, (p. 358). Only the a-oxy-acids
are capable of entering this simple and double " ester anhydride formation " by
the union of two molecules. Heat hastens the reaction (occurs on standing in the
dessicator). Conversely the ester anhydrides when heated with water absorb it
and the oxy-acids are regenerated.

Should the anhydride formation occur within one and the same
molecule of the oxy-acids, we get what are designated lactones
{Pittig, Annalen, 208, in ; 216, 27; 226, 322) : —

CH,.CH2.0H CHjj.CH.

I -H,0= I )0.

CHj.CO.OH CHj.CO ^

Y-Oxy-butyric Acid. y-Butyrolactone.

The ;'- and 5-oxy-acids (from mono- and dicarboxylic acids)
especially are adapted to this lactone formation, hence we distinguish

352 ORGANIC CHEMISTRY.

;'- and 5-lactones {Annalen, 216, 127). In the first we have a
chain of four, in the second a chain of five carbon atoms closed by
oxygen. This resembles the union in the anhydrides of the dibasic
acids. Generally the lactones are liquids, easily soluble in water,
alcohol and ether. They show neutral reaction, possess a faintly
aromatic odor, and can be distilled without decomposition. The
alkaline carbonates precipitate them from their aqueous solution in
the form of oils. The ^--lactones are characterized by great
stability. They are partially converted into oxy-acids by water,
but this only occurs after protracted boiling, whereas those of the
5-variety gradually absorb water at the ordinary temperature and
soon react acid {Berichte, 16, 373). Boiling alkaline carbonates
convert lactones into oxy-acid salts. The caustic alkalies effect this
more readily. If the oxy-acids are freed from their salts by the
mineral acids they at once break up into water and lactones. Heat
hastens the conversion.

The ^--lactones can be obtained : —

(i) By boiling the ^'-halogen fatty acids with water, or with
caustic alkalies, and then liberating them with mineral acids. The
lactones are produced even in the cold by the action of the alkaline
carbonates (p. 346).

Many y-derivatives, ?. ^., y-chlorbutyric acid (p. 226), decompose directly into
lactone and HCl (Berichte, 19, Ref. 13) when distilled.

(2) By digesting the unsaturated acids, in which the double union
occurs in the {p : ;') or (;' : 5)-position, with hydrobromic or sul-
phuric acid (diluted with i volume H2O) ; or by their distillation
\Berichte, 16, 373 ; 18, Ref. 229) : —

CHjiCH.CHj.CHj.CO^H = CHj.CH.CII^.CH^

Allyl Acetic Acid. [ t

o o.

Valerolactone.

(3) By the action of sodium amalgam upon the /--ketonic acids,
and the decomposition of the sodium salts by mineral acids (see
above). Unsaturated lactones are formed upon distilling ^-ketonic
acids {Berichte, 18, 2263), e. g., the two angelica lactones (p. 343)
from laevulinic acid : —

CH3.CO.CH2.CH2.CO.OH yields CHj.OCH.CH- and CH.iC.CHj.CH^

II II-
O — CO O CO

4. Finally, by the distillation of lactone carboxylic acids (split-
ting-off of CO.2), whereby the isomeric unsaturated acids are also
produced, owing to a rearrangement of the atoms.

Some lactones have their lactone union severed, and the elements

OXY- ACIDS. 353

of a halogen hydride added, through the action of HI, or by heat-
ing with hydrochloric or hydrobromic acid. The products in this
case are ^--halogen fatty acids {Berichte 19, Ref. 165) :—

CHj.CHj.CH^

i I + HI = CH,I.CH,.CH,.CO,H.

O CO 2222

With other lactones this transposition does not occur except in
the presence of alcohol. Then the esters of the halogen fatty
acids are formed {Berichte, 19, 513). The lactones are reduced to
fatty acids upon boiling with hydriodic acid. Ammonia converts
them into the amides of the ^--oxyacids, which rapidly regenerate
the lactones. Valerolactone, for example, unites with potassium
cyanide to form ^'-cyanvaleric acid, CH3.CH(CN).CH,.CH3.C02H
(p. 344 and Berichte, 19, Ref. 439). The lactones do not react
with phenylhydrazine.

(J-Caprolactone is the only known member of its class (p. 365).

Besides the 7 and (J-oxyacids some /Joxyacids (of the benzene series) are capa-
ble of yielding corresponding lactones {Berichte 16, 3001 ; 17, 415). These
^-lactones are much less stable, pass readily into their corresponding oxyacids, and
split oflf carbon dioxide with ease. The existence of an a-lactone seems also to
have been demonstrated {Berichte, 15, 579).

The divalent groups, attached to the two hydroxyl groups, in the
oxy-acids, are often called radicals: —

CH2_ CH,.CH

I I "~

co_ co_

Glycolyl. Lactyl.

OXY-ACIDS CJ-T,„03.

Carbonic Acid — CH.O, = CoC^
^ ^ \0H

GlycoUic Acid or I „ „ ^ — r-w /OH

Oxyacetic " f ^i"-i^i — ^"2\C02H

Lactic Acids or 1 r R n ~ r tt /OH

Oxypropionic Acids J ^z^i^i — "-a'^iXCOgH

Oxybutyric Acids C.H.O, = CjH./g^^jj

Oxyvaleric " C,H^,0, =<^^^,(^^^^

etc., etc.

I. Carbonic Acid, CHjOj — oxyformic acid — is the lowest member of the
series. It cannot exist free, and its character varies considerably from those of

/OH
the rest. From its symmetrical structure, CO^ qxt, and the fact that no differ-
ence exists in the OH groups, this compound is a dibasic acid, although very feeble.
30

3S4 ORGANIC CHEMISTRY.

Therefore it and its numerous derivatives will be treated later, after the other
dihydric acids.

2. GlycoUic Acid, C,HA = CH,(0H).C02H.

GlycoUic, or oxyacetic acid, is obtained according to the
methods given as follows : from ethylene glycol, from monochlor-
or brom-acetic acid, and from amido-acetic acid, CH2(NH2).
CO2H, by means of nitrous acid. It is produced, also, when nas-
cent hydrogen (zinc and sulphuric acid) acts upon oxalic acid : —

CO.OH CHj.OH

I +2H2= I + H^O;

CO.OH CO.OH

by oxidizing ethyl alcohol with nitric acid at ordinary temperatures
(with glyoxal and glyoxylic acid, p. 330) ; from glycosin and its
derivatives, and from glycerol by the action of silver oxide
{Berichte, 16, 2414).

The best method of preparing the acid is to boil chloracetic acid with alkahes
or calcium carbonate. The calcium salt first formed is decomposed with an
equivalent amount of oxalic acid and the filtrate concentrated (Berichie, 16,
2954).

GlycoUic acid is a thick syrup, which gradually crystallizes upon
standing over sulphuric acid. The crystals melt at 80° and deli-
quesce in the air. It dissolves easily in water, alcohol and ether.
When distilled it decomposes with formation of paraformaldehyde
(p. 192).

Its alkali salts are very deliquescent. The calcium salt, (C2H303)2Ca, with
3 and 4 HjO, is sparingly soluble in cold water (i part in 8 parts HjO at 10°),
and crystallizes in needles. The silver salt, (C2H303Ag)2 + HjO, is also
rather insoluble. The ethyl ester, CH2(OH).C02.C2H5, is a liquid, possessing a
specific gravity equal to 1.03, and boils at 150°.

Alcohol and acid radicals can replace the hydrogen in alcohol-
hydroxyl of glycoUic acid.

The acid derivatives are formed : —

(i) On heating glycoUic acid with monobasic acids: —

•^^^^XCO^H + C2H3O.OH = CH,/g^^^^»0 + H2O;

Acetogly collie Acid.
or by acting upon esters of the acid with acid chlorides : —

CH<C02.C,H, + C.HaOCl = CH2(goC;H30^ + HCl.

(2) By action of the alkali salts of acids upon esters of monochlor-acetic acid : —

CH2CI.CO2.C2H5 + C,H,O.OK = ^^■,(^q'^§^^ + KCI.

Potassium Benzoate. Benzoyl Glycollic
Ester.

OXY- ACIDS. 355

We obtain the alcohol derivatives when sodium alcoholates act on monochlor-
acetic acid : —

CH,a.CO,Na + C,H,.ONa= CH3/°^^?^^5 + NaCl.

Ethyl GlycoUic Acid.

Methyl Glycollic Acid.CH ^^^ ^s boils at 198°; ethyl glycollic acid,

CH2(O.C2H5).C02H, at 206°. Both are very stable, and boiling allcalies do not
decompose them.

The ^//^ifr-^j-^ifrj, like CHj^' pQ r H ' ''^^'^^'^ when chloracetic

esters are acted upon by sodium alcoholates. For their boiling
points see Berichte, 17, 486.

Thioglycollic Acid, CHj^^pj-. „, is both an acid and a mercaptan. It is

obtained from monochloracetic acid and potassium sulphydrate; from thiohy-
dantoin (see this), and its phenyl derivatives, vifhen they are heated virith alkalies
(Annalen, 207, 124). It is an oil, which is readily soluble in water, alcohol and
ether. Heat decomposes it. On adding ferric chloride to the acid solution, then
neutralizing with ammonia, we obtain a purple-red coloration. Thioglycollic acid
behaves like a dibasic acid, forming primary and secondary salts. This is due to
the SH group imparting the properties of the mercaptans. The barium salt,

CH2(' p^^Ba 4- 3H2O, dissolves with difficulty in water.
The acid (its alkali salts), on exposure to the air, oxidizes to —
DithiodiglycoUic Acid, Sji' p ij^ CO^H" "^' "^^ ^'^° ^^ produced by oxi-
dation with ferric chloride, or by the action of iodine upon potassium thioglycoUate
(Berichte, ig, 114). It is crystalline and fuses at 100° C.

ThiodiglycoUic Acid, S(' CH^ CO H' ^^^^ fr°™ '^^ action of chloracetic
acid upon potassium sulphide. It crystallizes in plates and melts at 129°. Potas-
slum permanganate oxidizes it to sulphodiacetic acid, 'S>0^{ ph^ CO^H' '^^ '^''
ter exhibits a deportment analogous to that observed with aceto-acetic acid, in that
its CH2-group is very reactive {Berichte, 18, 3241 and p. 307).

Thioglycollic acid, and also thioacetic acid (p. 262), like the mercaptans (p. 306),
unite with the aldehydes, ketones and ketonic acids to form compounds of the

type, R-.C^o rS'^'rn^H- Boiling concentrated hydrochloric acid resolves them

into their components {Berichte, 21, 478).

Thiocyanacetic Acid, CH2<^^q^, Sulphocyanacetic Acid, is formed
by the action of chloracetic acid upon KCNS. It is a thick oil. Its ethyl ester,
from chloracetic ester, boils about 220° C.

On boiling the latter (or thiohydantoin) with concentrated hydrochloric acid,

rhodanacetic acid, CHj/^^^j, is formed. This acid should probably be viewed

35 6 ORGANIC CHEMISTRY.

as pseudo-dioxythiazole, I ^CO {Berichte, 22, Ref. 19). Large leaflets,

CH„-S

CO— NH^

melting at 128°. It forms a benzylidene compound with benzaldehyde [Berichte,
22, Ref. 333). ,„TT

Rhodanic Acid, CH2<r ?.q c rK, tlie mixed anhydride of thioglycollic (see

above) and sulphocyanic acids, is obtained by the action of CNS(NH4) upon chlor-
acetic acid. It consists of yellow prisms or plates, and melts at 169° with decom-
position. Upon digestion with baryta water it splits up into thioglycollic and
hydro-sulphocyanic acids (Berichte, 19, 1 14; 22, Ref. 334). It, in all probability,

CH,-S ,
represents a thioxythiazole, \ ^CS.

CO— nh/

Anhydrides of Glycollic Acid.

Glycollic Anhydride, C^HeOs = CH2(OH).CO.O.CH2.C02H, the first
ester anhydride of glycollic acid (p. 354), is produced on heating glycollic acid to
100°. It is a solid, insoluble in alcohol, water and ether. It melts at 128-130°.
Boiling water changes it to glycollic acid.
CH^— O— CO

Glycolide, C^H^O^ := • ■ — the second ester anhydride of gly-

CO— O — CH^
collie acid (p. 354) — is obtained by strongly igniting glycollic acid (to 250°) or
tartronic acid, and by heating potassium or silver glycoUate (^Berichte, 14, 577).
It forms a powder almost insoluble in water, and melts at 220°. It returns to
glycollic acid when boiled with water. When heated with ammonia it yields

glycolamide, CH^v^ p^ ^^u , which boils at 120°. Formerly glycolide was sup-

posed to be an ester anhydride (p. 351) with the formula, CH2X co^' "^^^

present double formula is assigned it from its analogy to lactide (p. 359).

DiglycoUic Acid, C^HjOj, the alcohol anhydride of glycollic acid (p. 351),
is formed on boiling monochloracetic acid with lime, baryta, magnesia, or lead
oxide (also with glycollic acid), and in the oxidation of diethylene glycol,

'^Cch'ch'o}! (P- 3°4)> wi'li °''"C acid and platinum sponge. When sepa-
rated from its rather insoluble calcium salt with sulphuric acid, diglycoUic acid
crystallizes in rhombic prisms, which mell at 148°. Boiling alkalies do not alter
it. It is only when heated with concentrated hydrochloric acid to 120° that it
breaks up into glycollic acid. The acid is dibasic, yielding primary and secondary
salts.

3. Lactic Acids, or Oxypropionic Acids, CsHeOs.
There are two possible isomerides : —

CH3.CH(OH).COjH and CH2(OH).CH2.C02H
a-Oxypropionic Acid. ^-Oxypropionic Acid,

Ethidene Lactic Acid. Ethylene Lactic Acid.

(i) Ethidene Lactic Acid, Ordinary Lactic Acid of Fer-
mentation, CH3.CH(OH).C02H, is formed by a peculiar fer-
mpntation of sugar (milk sugar, cane sugar), gum and starch, in the

OXY-ACIDS. 357

presence of albuminoid substances (chiefly casein). It is, therefore,
contained in many substances which have soured, e,g., in sour milk,
in sour-kraut, pickles, also in the gastric juice. The lactic fermen-
tation occurs by the action of a particular, organized ferment, at
temperatures from 35-45°. Excess of free acid arrests it, but it is
renewed, if the acid be neutralized by alkalies.

The acid is artificially prepared by the methods already described,
p. 347 : — from a-chlor- or brom-propionic acid by boiling with alka-
lies ; from a-propylene glycol by oxidation with nitric acid ; from
alanine, CH3.CH(NH2).C02H, by means of nitrous acid, and by
the action of nascent hydrogen upon racemic acid. Other methods
consist in heating grape sugar and cane sugar with water and 2-3 parts
barium hydrate, to 160°, and a-dichloracetone, CHj.CO.CHClj,
with water to 200°.

Preparation. — Lactic acid is usually obtained by the fermentation of cane sugar.
2 Kilograms of cane sugar and 1 5 grams of tartaric acid are dissolved in 1 7 litres
of water, and the solution allowed to stand several days. Then add 100 grams
decaying cheese, previously macerated in 4 litres of sour milk, and 1200 grams
zinc-white, and let the mixture ferment at 40°-45° for 8-10 days (longer fermenta-
tion changes the lactic into butyric acid). The entire mass is next brought to
boiling, 61tered, and the filtrate strongly concentrated. The zinc lactate which
separates out is decomposed by H^S, the zinc sulphide removed by filtration, and
the filtrate containing the lactic acid evaporated on the water bath. To separate
the lactic acid produced in this manner from the mannitol (formed simultaneously)
dissolved by it, shake the residue with ether, which will not dissolve the mannitol.

Fermentation lactic acid is a thick syrup, with a specific gravity
r. 215, but it cannot be obtained crystallized. It is miscible with
water, alcohol and ether, and absorbs moisture when exposed to
the air. . Placed in a dessicator over sulphuric acid it partially de-
composes into water and its anhydride. When distilled it yields
lactide, aldehyde, carbon monoxide and water.

It is optically inactive. Penicillium glaucum converts its ammo-
nium salt into active sarcolactic acid (Lewkowitsch, Berichte, 16,
2720).

Heated to 130° with dilute sulphuric acid it decomposes into
aldehyde and formic acid (p. 350) ; when oxidized with chromic
acid, acetic acid and carbon dioxide are formed. Heated with
hydrochloric acid, it changes to a-brompropionic acid :

CH3.CH(OH).C02H + HBr = CHj.CHBr.CO^H + H^O.
Hydriodic acid at once reduces it to propionic acid.

The sodium salt, CjHjOaNa, is an amorphous mass. When heated with metal-
lic sodium, the alcoholic hydrogen is replaced, and we get the disodium compound :

C3H,03Na, = CH3.Ch/0^^*j^.^.

35 8 ORGANIC CHEMISTRY.

The calcium salt, (C3H503)2Ca + SH^O, crystallizes in hard warts, consisting
of concentrically grouped needles. It is soluble in ten parts cold water, and is
very readily dissolved by hot water and alcohol.

The zinc salt, (C3H503)2Zn + 3H2O, crystallizes in shining needles, which
dissolve in 58 parts cold "and 6 parts hot water. "Xh.^ iron salt, (CjHjOjjjFe
+ 3H2O, is very sparingly soluble in water, and yields crusts consisting of deli-
cate needles. It is also obtained by boiling whey with iron filings. The salts of
lactic acid are called lactates.

Ethyl Lactic Ester, CH3.CH(OH).C02.C2H5, is formed when lactic acid and
anhydrous alcohol are heated to 170°. It is a neutral liquid, which boils at 156°.
It is soluble in water, and rapidly decomposes into lactic acid and alcohol. When
potassium and sodium act upon the ester, they replace alcoholic hydrogen, and if
the product be treated with ethyl iodide we obtain : —

Ethyl Etholactic Ester, CR,.CYi( f^'f^'^f^^-f^ . This is formed also on heating

a-chlorpropionic ester (or lactyl chloride) with sodium ethylate : —

CH3.CHCI.CO2.C2H5 + C2H5.0Na = CH3.Ch/°^2^5^ + NaCl.

It boils at 156°, and is insoluble in water. When the ester is boiled with caustic
soda ethyl-lactic acid is produced.

Ethyl Lactic Acid, CH^.CH^ P^ Vr *. A strongly acid syrup, yielding crys-
talline salts, which revert to the diethyl ester when acted upon with ethyl iodide.
Hydriodic acid breaks it up into lactic acid and ethyl iodide : —

CH3.Ch/°^^2^5 + hi = CH3.Ch/0^^jj + C2H5I.

/O C H O

Aceto-lactic Acid, CHj.CH^ „U 2 ' , occurs together with sarcolactic acid in

beef extract. It results from the interaction of lactic acid, as well as of sarcolactic
acid, with acetic acid. Its amorphous zinc salt distinguishes it from the other
lactic acids (Berichte, 22, 271 1).

On adding lactic acid to a mixture of nitric and sulphuric acids (p. 349) it dis-
solves, forming nitrolactic acid, CH, CH^'pl-. tt^. A yellow liquid, slightly
soluble in water. It decomposes readily. Its specific gravity equals 1.35.

Lactyl Chloride, CHj.CHj'^P^ ™, a-chlorpropionyl chloride, is obtained by

the distillation of dry lime lactate (l part) with PCI5 (2 parts). It is imperfectly
separated from the PCI3O which is formed at the same time. With water it yields
a-chlorpropionic acid ; with alcohol o-chlorpropionic ester. Lactic acid is regen-
erated when the chloride is heated with alkalies.

ANHYDRIDES OF LACTIC ACID.

Lactie«'Anhydride, CgHjjOj, is the first ester anhydride of lactic acid (p. 351).
It is formed when lactic acid is heated to 130°, or when it stands over sulphuric
acid ; further, by the action of potassium lactate upon a-brompropionic acid : —

CH3.CH.OH CO,H CH3.CH.OHCO2H

I +1 =11 + KBr.

CO.OK CHBr.CH, CO— O— CH.CH,

ANHYDRIDES OF LACTIC ACID. 359

It is an amorphous powder, almost insoluble in water. Tbe alkalies imme-
diately convert it into lactic acid.

T t-H r w r, _ CH3.CH— O— CO

L,actiae, CgUjU^ — r^n <-. /-.'ti ^tt ' ''^^ second ester anhydride, is

^ CH.CHg

obtained by distilling lactic acid, or by passing dry air through the acid heated to
150°. It crystallizes from alcohol in rhombic plates, melting at 124.5° and boiling
at 255°. It dissolves slowly in water with gradual formation of lactic acid. The
vapor density agrees with the formula, C^Ufi^{Berichte, 7, 755). It was for-
merly believed that it was " an inner anhydride," CHj.CHXq

CO/
CH3— CH— O-CH.CH3
Dilactic Acid, CjHjjOs = | The diethyl ester is

, COjH CO2H.

produced on heating a-brompropionic ester with sodium lactic ester (p. 351), in
alcoholic solution. It boils at 235°, and when heated above 100° with water,
breaks up into lactic acid and alcohol.

Substituted Lactic Acids : —

)3-Chlorlactic Acid, CH2C1.CH(0H).C05,H = C3H5CIO3, is formed by the
oxidation of epichlorhydrin and o-chlorhydrin, CHjCl.CH(0H).CH2.0H, with
concentrated HNO3 ; by the addition of hypochlorous acid to acrylic acid (together
with a-chlorhydracrylic acid (p. 362) : —

CH^iCH.COjH yields CH2C1.CH(0H).C02H and CH2(OH).CHCl.C02H ;
Acrylic Acid. J8-Chlorlactic Acid. a-Chlorliydracrylic Acid.

and by the addition of HCl to epihydrinic acid (glycidic acid) : —
CHj.CH.CG^H _^ jj(-,j ^ CH2C1.CH(0H).C02H.

Brom- and iod- acetic acids are obtained in the same manner (Berichte, 14,
937). The first melts at 89°-90°, the second at ioo°-ioi°. ;3-Chlorlactic acid
is also formed from monochloraldehyde by the action of hydrocyanic and hydro-
chloric acids (p. 347).

jS-Chlorlactic acid crystallizes from water in large transparent plates or prisms,
and melts at 78°-79°. Silver oxide converts it into glyceric acid; when reduced ,
with hydriodic acid it becomes /3-iodpropionic acid. Heated with alcoholic
potash it is again changed to epihydrinic acid (see above), just as ethylene oxide
is obtained from glycolchlorhydrin (p. 300).

Dichlorlactic Acid, CHCl2.CH(0H).C02H, is obtained from dichloraldehyde
through the cyanide (p. 347). It forms deliquescent plates, melting at 77°- It
reduces ammoniacal silver solutions.

Trichlorlactic Acid, CCl3.CH(OH).C02H, is made by heat-

ing chloralcyanhydrin, CClg.CH^ P^^ (p. 196), with concentrated

hydrochloric acid {Berichte, 17, 1997). It is a crystalline mass,
melting at 105°-! 10°, and soluble in water, alcohol and ether.
Alkalies easily change it to chloral, chloroform and formic acid.
Zinc and hydrochloric acid reduce it to dichlor- and mono-chlor-

360 ORGANIC CHEMISTRY.

acrylic acids (p. 237). Its ethyl ester melts at 66°-67°, and boils
at 235°. The best method of preparing it consists in heating
chloralcyanhydrin with alcohol and sulphuric acid (or HCl, Be-
richte, 18, 754).

Because trichlorlactic acid yields chloral without diflficulty, it is converted quite
readily, by different reactions, into derivatives of chloral and glyoxal. It forms
glyoximes with hydroxylamine, and glycosin with ammonia (p. 325, and Berichte,

18, 754).

When trichlorlactic acid is heated to 150° with excess of chloral, we obtain
trichlorethidene-trichlorlaclic ester : —

CCla.CH/^QQjj + CHO.CCI3 = CCI3.CH/ ^ ^CH.CCls + H^O.

The same body, C^HjCljOj, called Chloralide, was at first prepared by heat-
ing chloral (l part) with fuming sulphuric acid {3 parts) to 105°. It crystallizes
from alcohol and ether in large prisms, is insoluble in water^melts at ri4°-il5°
and boils at 272°-273°. When heated to 140° with alcohol, it breaks up into
trichlorlactic ester and chloral alcoholate. Chloral also unites with lactic and
other oxy-acids, like glycoUic, malic, salicylic, etc., forming the so-called chloral-
ides {Annalen, 193, l).

Tribromlactic Acid, CBr3.CH(OH).C02H, from bromal cyanhydrin, melts
at 141°- 143° and unites with chloral and bromal to corresponding chloralides and
bromalides.

a Thio-lactic Acid, CH3.CH(SH).C02H, Thio-dilactic Acid,
/CH(CH3).C0,H jj^; ,jj J jj g /CH(CH3).CO,H

^\CH(CH3).CO,H ^^^ uitniodiiacHc Acm, ^2\CH(CH3).C02H' ^'^ °^
tained from n-chlorpropionic acid by methods analogous to those employed with
thioglycoUic acids (p. 318). They can also be prepared from racemic acid by the
action of hydrogen sulphide. Racemic acid yields alkyl-thio-oxypropionic acids,
with the mercaptans ; —

CH CO /yrl

' I + CgHsSH = CHj.^^^-^s^s {^Berichte, 18, 262).

Cystein is probably an amido-thiolactic acid, CHj.Cj^rjL j.COjH. It is

obtained from cystin by reduction with tin and hydrochloric acid. A crystalline
powder, very soluble in water, and yielding an indigo-blue color with ferric chlo-
ride. In the air it rapidly oxidizes to cystin (Berichte, 18, 258, and 19, 125).
Cystin, CgHjjNjO^Sj, probably dithio-diamido-dilaclic acid,

^2x ^}^^H'vlSIH^ m^H' o*^*^""^^ '" some calculi and urinary sediments. It
forms colorless leaflets. It is insoluble in water and alcohol, but dissolves in acids
and alkalies.

The Mercapturic Acids (^Berichte, 18, 258) are probably acetyl compounds
of alkyl-thio-lactic acids.

Sarco-lacfic or Paralactic Acid is a peculiar modification of
fermentation lactic acid. It is present in different animal organs,
especially in the juice of the flesh. Liebig's Beef Extract furnishes

ETHYLENE LACTIC ACID. 361

It. In all its transpositions it behaves like ordinary lactic acid,
hence we must accept the same chemical structure for it. The
existence of the two modifications is explained by the asymmetry of
a carbon atom in the acid (p. 63). Sarco-lactic acid is distin-
guished from the ordinary variety by turning the plane of polariza-
tioii to the right (the ordinary acid is inactive) and by differences
in Its salts. When heated to 130° it yields lactic anhydride (p.
358), which water changes back to ordinary lactic acid.

Its calcium salt, {C^fl^fis., contains four molecules of water, and is more
sparingly soluble in water than that of ordinary lactic acid. The zinc sail con-
tains two molecules of water, yields shining, thick prisms and is more soluble (l
part in 17 parts H^O at 15°) in water than the zinc salt of ordinary lactic acid.

2. Ethylene Lactic Acid, or Hydracry lie Acid, CH^COH).
CH2.CO2H, /J-oxypropionic acid, is obtained from /3-iodpropionic
acid on heating it with moist silver oxide, or on boiling with
water: —

CH^I.CH^.CO.H + AgOH = CH.COHj.CH^.CO^H + Agl;
P-Iodpropionic Acid. ;3-Oxypropionic Acid.

by the careful oxidation of /J-propylene glycol (p. 308), or by con-
version of the same into chlorhydrin and ^-chlorpropionic acid : —
CH^.OH CHXl CH.Cl CH,.OH

CHj CH. CH„ and CH„ ;

I I I I '

CH^.OH CHj.OH CO.OH CO.OH

by the action of CNK and HCl upon ethylene chlorhydrin : —

CHj.OH CH^.OH CH^.OH

I yields | and | ;

CH2CI CHj.CN CH^.COjH

and from ethylene oxide through the agency of CNH and HCl.
The formation of the acid from acrylic acid by heating with aqueous
sodium hydroxide to 100° is also very interesting.

The free acid yields a non-crystallizable, thick syrup. When
heated alone, or when boiled with sulphuric acid (diluted with i
part HjO), it loses water and forms acrylic acid (hence the name
hydracrylic acid, p. 350) : —

CH2(OH).CH2.C02.H = CHj.-CH.COjH -f- H^O.

Hydriodic acid again changes it to /3-iodpropionic acid. It yields
oxalic acid and carljon dioxide when oxidized with chromic acid or
nitric acid.

362 ORGANIC CHEMISTRY.

The sodium salt, CjHjOjNa, is indistinctly crystalline, and melts without
change at 142-143°. It loses water at 150°, and forms sodium acrylate. The
calcium salt, (C3H503)2Ca + 2H2O, forms large rhombic prisms, loses its water
of crystallization at 100°, and fuses at 140-145° without decomposition. Heated
to 190° it parts with water and becomes calcium acrylate. The zinc salt,
(C3H503)2Zn -f- 4H2O, crystallizes from a moderately concentrated solution, in
large, shining prisms, and dissolves in an equal part of water at 15°. If the solu-
tion is very concentrated it will only crystallize with difficulty. The zinc salt is
soluble in alcohol, whereas the latter precipitates zinc a-lactate and paralactate.

a-Chlorhydracrylic Acid, CHjiOHj.CHCl.CO^H, from acrylic acid, is a
liquid, ^and is converted into hydracrylic acid by nascent hydrogen ; it yields gly-
cidic acid with the alkalies.

4. Oxybutyric Acids, QHgOs = C3H6(OH).C02H.
Four of the five possible oxybutyric acids are known : —
(i) a-Oxybutyric Acid, CH3.CH2.CH(OH).C02H, isobtained
by boiling a-brombutyric acid with moist silver oxide or caustic
potash, and from propionic aldehyde with hydrocyanic and hydro-
chloric acids. It is crystalline and deliquescent in the air. It melts
at 43-44°. The zinc salt, {Q.^^O^.[Lvi -\- 2H2O, crystallizes from
water in white leaflets, sparingly soluble in cold water. When
oxidized with chromic acid, the acid decomposes into propionic
acid and CO2.

(2) ^-Oxybutyric Acid, CH3.CH(OH).CH2.C02H, is formed by the action
of sodium amalgam upon acetoacetic ester (p. 338), by the oxidation of aldol (p.
321) with silver oxide, and from n-propylene chlorhydrin, CH3.CH(OH).CH2Cl,
(p. 308) by the action of CNK and subsequent saponification of the cyanide. It is
a thick, non-crystallizable syrup, which volatilizes with steam. The Ca- and Zn-
salts are amorphous and readily soluble in water. When heated the acid decom-
poses (like all j8-oxy-acids, p. 350) into water and crotonic acid, CHg.CHiCH.
COjH. An optically active (3-oxybutyric acid has been isolated from diabetic urine
{Berichte, 18, Ref. 451).

(3) ^Oxybutyric Acid, CH2(OH).CH2.CH2.C02H, is not
very stable in a free condition, because it readily breaks up, like all
^'-oxy-acids (p. 351) into water and its inner anhydride butyrolac-
tone, C4He02. The acid (its salts) is obtained by letting sodium
amalgam act on succinyl chloride, C2Hj(CO.Cl)2, and from the
bromhydrin of /^-propylene glycol (p. 308) by means of CNK and
the after-saponification of the cyanide, and from butyrolactone car-
boxylic acid (see this), by the splitting-off of CO2 (^Berichte, 16,
2592) ; by the distillation of y-chlorbutyric acid (p. 352) ; and from
the reaction product of ethylene chlorhydrin and aceto-acetic ester
by decomposing it with baryta {Berichte, 18, Ref. 26). Butyrolac-
tone, obtained from its salts, is a neutral, thick liquid, boiling at
203° ; its specific gravity equals 1. 130 at 20°. , It is miscible with
water, and is precipitated by soda.

OXYVALERIC ACIDS. 363

(4) a-Oxyisobutyric Acid, ^^^')C(OH).CO,H, was first ob-
tained by the action of CNH and HCl on acetone (p. 203), hence
called acetonic acid : —

^^3\co yields CH3\ /OH

CH3/'-" y*"*^ CH3/C\CO,H.

It is further obtained from acetone chloroform (p. 205) ; from ox-
alic ester by the action of CH3I and Zn (see p. 347), hence termed
dimethyloxalic acid, or better, dimethyl-oxyacetic acid ; from a-
bromisdbutyric acid on boiling with baryta water : —

(CH3)2CBr.C02H + H^O = (CH3)2C(OH).C02H + HBr:

from /9-isoamylene glycol by oxidation with nitric acid (p. 310)
(hence called butyl lactic acid), and from isobutyric acid, QHgO^,
by oxidizing with potassium permanganate (p. 227). Oxy-isobutyric
acid crystallizes in prisms and is very soluble in water and ether.
It sublimes at 50°, in long needles, melts at 79° and distils at 212°.
Methacrylic acid is formed when PCI3 acts on its esters (p. 240).
When oxidized with chromic acid, it breaks up into acetone and
carbon dioxide.

The barium salt, {<Z^^0^^3., consists of easily soluble shining needles.
The zinc salt, (C^Hj03)2Zq + sH^O, crystallizes in microscopic, six-sided
plates, sparingly soluble in water.

(5) i3-Oxyisobutyric Acid, CHj,OH.CH(CH3).C02H, has not been ob-
taiaed.

5- Oxyvaleric Acids, QHioO, = QH8(0H).C0,H.

•

(1) ffi-Oxyvaleric Acid, CH3.CH2.CH2.CH(OH).C02H, has been obtained
from normal a-bromvaleric acid and from normal butyric aldehyde. It forms
table-like crystals, melting at 28-29° {Berichte, 18, Ref. 79).

(2) y-Oxyvaleric Acid, CH3.CH(OH).CH2.CH2.C02H, like all the 7-oxy-
acids, decomposes when separated from its salts into water and its inner anhydride,
valerolactone, CjHgO^ (p. 352). The latter is prepared directly from 7-brom.
valeric acid (from allyl acetic acid, p. 241), on heating it with water above 100°. It
may be obtained more readily by acting on /3-aceto-propionic acid (Isevulinic acid,
P- 343). with sodium amalgam and water. Sulphuric acid is added to the solu-
tion and the latter shaken with ether. Valerolactone is a coloriess liquid which
does not solidify at .—18°, and boils at 206-207°. It is miscible with water, form-
ing a neutral solution from which it is reprecipitated by alkaline carbonates.
When boiled with alkalies, baryta or hme it forms 7-oxyvalerates. It yields suc-
cinic acid when oxidized with nitric acid (Annalen, zo8, 104).

(3) a-Oxyisovaleric Acid, (CH3)2.CH.CH(OH).C02H, is obtained from a-
bromisovaleric acid and from isobutyraldehyde,(CH3)2CH.CHO,bymeansof CNH
and HCl. It crystallizes in large rhombic plates, which melt at 86° and volatilize

364 ORGANIC CHEMISTRY.

at 100°. Its ethyl ester, boiling at 175°, is obtained from oxalic ester by zinc and
isopropyl iodide. Heated witli sulphuric acid it decomposes into isobutyraldehyde
and formic acid, and when oxidized with chromic acid it yields isobutyric acid
and COj. Heated to 200° it affords an anhydride, (CjH ,02)2 (?) (p. 358), resem-
bling lactide. It mells at 136°.

(4) ^-Oxyisovaleric Acid, (CH3)2C(OH).CHjj.C02H, is formed on oxid-
izing dimethyl allylcarbinol (p. 121) with chromic acid, or isopropyl. acetic acid,
(CH3)2.CH.CH2.C02H, with an alkaline KMnOi solution (p. 346). It is a
liquid which is not volatile with steam. Chromic acid oxidizes it to acetone, acetic
acid and carbon dioxide. ptr »

(5) Methyl-ethyl Oxyacetic Acid, }, -A ^C(0H).C02H, a-methyl-a-oxy-

butyric acid, is obtained from methyl-ethyl acetic acid (p. 229), by oxidation with
a solution of potassium permanganate ; from oxalic ester by means of CH3I,
C2H5I and zinc ; and from methyl-ethyl ketone by means of CNH and HCl. It
is crystalline, melts at 68°, and sublimes at 100°. Hydriodic acid reduces it to
methyl-ethyl acetic acid, while CrOj oxidizes it to methyl-ethyl ketone and CO2.
Its ethyl ester boils at 165°. CH'X

(6) a-Methyl-/3-oxybutyric Acid, ^„ „„,(-,„, ^CH.COjH, is obtained

from methyl aceto acetic ester, CH3.CO.CH(CH3).C02.C2H5 (p. 340). It is a
liquid, which decomposes, when distilled or if heated with HI, into water and
methyl crotonic acid.

6. Oxycaproic Acids, CgHi^Og = C5H,o(OH).C02H.

(i) a-Oxycaproic Acid, CH3.(CH2)3.CH(OH).C02H, is probably the so-
called leucic acid, obtained from leucine by the action of nitrous acid.

It is crystalline, melts at 73°, and sublimes near 100°. The oxycaproic acid
obtained from bromcaproic acid appears to be different. This compound melts at
60-62° [Berichte, 14, 1401).

(2) 7-Oxycaproic Acid, CH3.CHj.CH(OH).CH2.CH2.C02H, like a y-oxy-
acid, decomposes when free into water and its lactone, Caprolactone, CjHidOj.
The latter is obtained from bromcaproic acid (from hydrosorbic acid and HBr, p.
245), on heating the latter with water [Annalen, 208, 66), and from arabinose-
carbonic acid, CjHjjO,, by reduction with hydriodic acid {Berichte, 20, 339).
It is a liquid, boiling at 200°, and dissolves in 5-6 volumes H2O at 0°. On heat-
ing, caprolactone again separates. Nitric acid oxidizes it to succinic acid.

(3) d-Oxycaproic Acid, CH3.CH(OH).(CH2)3.C02H, -is formed from y-
aceto-butyric acid (p. 344). It furnishes a j-lactone (p. 353), which melts at 18°,
and Boils at 230°. It forms a neutral solution with water, but this becomes acid
after some time.

(4) y-Oxyisocaproic Acid, (CH3)2.C(OH).CH2.CH2.C02H. When free,
this breaks up into water and the corresponding lactone, Isocaprolactone,
CjHjgOj. The latter appears in oxidizing isocaproic acid with KMnO^ or
HNO3 ; by the distillation of terebic acid (see this), and in the transposition of
pyroterebic acid (p. 241), when heated alone or with hydrobromic acid [Annalen,
208, 55) :—

(CH3)2C.CH2.CH2
(CH3)2C:CH.CH2.CO.OH yields | |

O- -CO.

Pyroterebic Acid. Isocaprolactone.

Isocaprolactone melts near 7°, boils at 206-207°, ^^^ '^ soluble in double its
volume of water at 0°. When the solution is heated, it becomes turbid and the
lactone separates. Dilute nitric acid oxidizes a CHj group in caprolactone (also
in valerolactone) to carboxyl {Berichte, 15, 2324).

AMIDES OF THE DIHYDRIC ACIDS. 365

(5) >-Oxy-a-methylvaleric Acid, CH3.CH(OH).CHi,.CH/^Q Sjj and

its lactone, a-Methylvalerolactone, or symmetrical caprolactone,
CHj.CH.CHj.CH.CHj

I I , are obtained from /3-aceto-isobulyric acid (p. 344), by

O CO

the action of nascent hydrogen, and by reducing saccharin, CjIIjjO^, with hy-
driodic acid {Bericfite, i5, 1821). The lactone boils at 206°, and dissolves in 20
volumes of water. Further heating with HI, changes it to methyl-propyl acetic
acid (p. 230).

(6) 7-Oxy-/3-methylvaleric Acid, CH3.CH(OH).CH(CH3).CH2.C02H,
and its lactone, |8-methyl valerolactone, are obtained from ;8-aceto-butyric acid (p.
344). The lactone boils at 210°.

(7) Oxyheptylic Acids, C,Hn03.

The heptolactone, C^Hj^Oj, corresponding to y-oxyheptylic acid, is formed
on reducing teracrylic acid, C^HjjOj (p. 241), with hydrobromic acid, just as
iso-caprolactone is obtained from pyroterebic acid (see above). Heptolactone
melts at 11°, and boils at 220°. It dissolves in 12 volumes of water at o°-

Many other higher oxy-fatty acids have been obtained from oxalic ester by
means of propyl iodide, amyl iodide, etc., and zinc, and also from the higher
aceto-acetic esters, by the use of sodium amalgam. The unsaturated acids, alfyl
oxyacetic add, C^ii^.C}i{0}i).CO ^}ii, snAdiallyl oxyacelic acid, (C3H5)2C(OH).
CO2H, are produced in a similar manner.

UNSATURATED OXY-ACIDS, CnH^n-jOj.

But few of this class are known.

(i) Oxyacrylic Acid, C3H4O3 = CH(0H):CH.C02H, appears to form
upon boiling ;3-chloracrylic ester with baryta. It is very unstable, and passes
rapidly into malonic acid.

(2) Oxycrotonic Acid, Cfifi^, is not known in a free condition. The
alkylized /3-oxycrotonic acids : —

CH3.C(O.CH3):CH.C02H and CH3.C(O.C2H5):CH.C02H,
Methyloxycrotonic Acid. EthyloxycrotoHic Acid.

have been prepared from /3-chlorcrgtonic and chlorisocrotonic acids by the action
of sodium methylate and ethylate. Both are crystalline, insoluble in water and
very readily sublimed. The first melts at 128°, the second at 137°.

(3) Oxyangelic Acid, C5H3O3. The lactones of the y- and d-oxy acids
have been obtained by the distillation of Isevulinic acid (p. 343).

AMIDES OF THE DIHYDRIC ACIDS.

In the dihydric acids both the alcoholic and acid hydroxyl group can be re-
placed by the amid-group, NH^. In the first instance amic or amido-acids result,
while in the second case we get the isomeric acid amides (p. 25S). The imides
result by substituting the divalent acid radicals for two of the hydrogen atoms of
ammonia (p. 353) : —

„„ /OH PH /^^2

C"<CO.NH„ ^"^XCOOH

Glycolamide. Glycolamidic Acid.

CHj.CH. ^Q >.

Lactimide,

366 ORGANIC CHEMISTRY.

1. Amides.

Glycolamide, C2H5NO2 = CHj^^^ ^„ , is directly prqduced on heating

glycolide (p. 3'S6) with dry ammonia, or from acid ammonium tartronate when
heated to 150°. It crystallizes in needles, melting at 120°, possesses a sweet taste,
and dissolves easily in water, but with difficulty in alcohol. When boiled with
alkalies it breaks down into glycoUic acid and ammonia.

Lactamide, C,H,N02 = CHj.CH'^ pq -j^tt , is obtained by the union of lac-
tide with ammonia, and upon heating ethyl lactic ester with ammonia. It forms
crystals, readily soluble in water and alcohol, and melts at 74°. Boiling alkalies
break it up into lactic acid and ammonia.

Lactimide, C3H5NO = CgH^OiNH, is produced by heating alanine,

CHg.CH^pQlj, in a current of HCl to 180-200°. It consists of colorless
leaflets or needles, which melt at 275°, and dissolve readily in water and alcohol.

2. Amic or Amido-Acids.

Here the alcoholic hydroxyl is replaced by the group NH.^: —

CHj.OH CHjj.NHj

I and I

CO.OH CO.OH

GlycoUic Acid Glycolamidic Acid.

It is simpler to view them as amido-derivatives of the mono-
basic fatty acids, produced by the replacement of one hydrogen
atom in the latter by the amido-group ; —

CH. CH,.NH„

I I :

CO.OH CO.OH

Acetic Acid. Amidoacetic Acid.

Hence they are usually called amido-fatty acids. The firm union
of the amido-group in them is a characteristic difference between
these compounds and their isomeric acid amides. Boiling alkalies
do not eliminate it (similar to the amines). Several of these amido-
acids occur already formed in animal organisms. Great physio-
logical importance attaches to them here. They have received the
name alanines or glycocolls from their most important representa-
tives.

The general methods in use for preparing the amido-acids
are : —

(i) The transposition of the monohalogen fatty acids when heated
with ammonia (similar to the formation of the amines from the
alkylogens, p. 157):—

CH^Cl.COjH + 2NH3 = CH2(NH2).C02H + NH^Cl.

Monociilor-acetic Acid. Amido-acetic Acid.

AMIDES OK THE DIHYDRIC ACIDS. 367

(2) The reduction of nitro- and isonitroso-acids (p. 214) with
nascent hydrogen (Zn and HCl) :—

CH2(NOj).CH,.C02H + 3H2 = CH2(NH2).CH2.C02H + zU^O.

P-Nitropropionic Acid. |5-Amido-propionic Acid.

(3) Transposition of the cyan-fatty acids (p. 262) with nascent
H(Zn and HCl, or by heating with HI), in the same manner that
the amines are produced from the alkyl cyanides (p. 159) : —

CN.CO.OH + 2H2 = CH2(NH2).C02H.
Cyanformic Acid. Amido-acetic Acid.

Cyanformic acid and glycocoll are formed from dicyanogen by
the same method.

(4) A synthetic method consists in heating the aldehyde-ammo-
nias with hydrocyanic acid and hydrochloric acid (p. 190) : —

CH3.Ch/^H, ^ ^j^jj _ CH3.CH^^^^ + H,0.

The amido acids are then obtained on boiling the products with
hydrochloric acid.

A more advantageous method consists in converting the cyanides of the aldehydes
(p. I go) into amid-cyanides by means of alcoholic ammonia (in equivalent quan-
tity) :-

CH,.CH/g^ + NH3 = CH3.CH/^^^ + H,0,

and saponifying these with hydrochloric acid (BertcAU, 14, 1965). In this man-
ner the ketones can also be changed through the cyanides (p. 255) to amido-
acids: —

(CH3),C0 forms (CH3),c/^H2^.

The aldehydes, too, can be converfed into amido-acids by means of ammonium
cyanide {Berichte, 14, 2686).

(5) The conversion of the unsaturated acids upon heating them to 100° with
ammonia. This seems to be a very common method. Thus, crotonic acid, by this
treatment, becomes /5-amido-butyric acid (p. 372). Aspartic acid results in a simi-
lar manner from fumaric and maleic acids [Berkhte, 21, Refs. 86 and 523).

As the amido-acids contain both a carboxyl and an amido-group,
they are acids and bases (amines). They yield salt-like derivatives
with metallic oxides and with acids, and are capable also of directly
combining with certain salts. Since, however, the carboxyl and
araido-groups mutually neutralize each other, the amido-acids show
neutral reaction, and it is very probable that both groups combine
to produce an ammonium salt : —

V

ch3.ch(Nh^jj = ch3.ch(NH,\o.

368 ORGANIC CHEMISTRY.

The existence and method of producing trimethyl glycocoll or
betaine would indicate this (p. 316). A separation of the two
groups would again occur in the formation of the salts.

The hydrogen of the CO.OH group can be replaced by alcohol radicals with
formation of esters, which are, however, unstable. On the other hand, the hydro-
gen of the amido-group can be replaced by both acid and alcohol radicals. The
acid derivatives appear when acid chlorides act upon the amido-acids or their
esters : —

CH<co;h + C.HaO.Cl = CH,(NH.C.H30 ^ j^^l;

Acetyl Amido-acetic Acid,

whereas the alcohol derivatives are obtained by the action of the amines on sub-
stituted fatty acids : —

CH,C1.C0,H + NH(CH3), = CH./^^Jgs)^ + hCI.

Dimethyl Glycocoll.

The amido-acids are crystalline bodies with usually a sweet, taste,
and are readily soluble in water. As a general thing, they are
insoluble in alcohol and ether. Consult Berichte, 18, 388, upon
active and inactive amido acids. They are not affected by boiling
alkalies, but when fused they decompose into salts of the fatty acids
and into amines or ammonia. By dry distillation (with baryta
especially) they yield amines and carbon dioxide : —

CH^.Ch/^^^^jj = CH3.CH,.NH, + CO,.

Ethylamine.

Nitrous acid converts them into oxy-acids : —

CH<?o;h + NO.H = CH,/OH ^ ^ ^^ ^ H,0.
Glycollic Acid.

When potassium nitrite is allowed to act on the hydrochlorides
of the esters of the amido-acids, esters of the diazo-fatty acids (p.
373) are produced. Their formation serves as a test for even
minute quantities of the amido-acids ( Berichte, 17, 959). Ferric
chloride yields a red color with all the amido-acids. Acids dis-
charge the same.

By continuing the introduction of methyl into the amido-acids it is possible to
entirely split off the amido-group. Unsaturated acids result. Thus, a-amidopro-
pionic acid yields acrylic acid, and a amido-butyric acid yields crotonic acid (.5;?--
ichte, 21, Ref. 86).

Amido-anhydrides are produced by the elimination of water from the amido-
acids. They correspond to the ester anhydrides (p. 351). When this change
occurs with glycocoll and glycollic acid (p. 351) two molecules unite (Berichte, 2\,
Ref. 254, and 22, 793) : —

2CH /^'^^ Yield CH /NH-CO\p„
^^"■i\CO^n yield CH2^^Q_j_jj^^t.H2.

Glycocoll.

AMIDES OF THE DIHYDRIC ACIDS. 369

The 7- and d-amido-acids are capable of forming amido-anhydrides by inner con-
densation. In tliis respect they are analogous to 7- and rf-oxy-acids. This new
class of compounds has been designated lactams (compare the lactams of the
aromatic series). They contain closed chains of five and six members. Thus,
7-amido-butyric acid yields pyrrolidon (belonging to the pyrrol series) {Berichte,
22, 3338; 23, 888) :—

.CH„.NH. ,CH„.NH

CH / = CH / I + H,0.

^CHj.COjH ^CH^.CO

(S-Amido-valeric acid, CH2(NH2).CH2.CH2.CH2.C02H, is similarly converted
into oxy-piperidine, CjHgNO (or piperidon).

Taurine, described p. 319, belongs to the amido-acids.

Glycocoll, C2H5NO2

Alanine, CsHjNOj

Propalanine, C4H9NO2

Butalanine, C5H11NO2

Leucine, CeHjaNOa.

I. Glycocoll, Amido-acetic Acid, C2H5NO2 = CH2(NH2).C02
H, is produced in the decomposition of various animal substances,
like hippuric acid, glycocholic acid or glue (hence the name
glycocoll : glucus, sweet ; kolla, glue), when they are boiled with
alkalies or acids. It is obtained synthetically : by heating mono-
chloracetic acid with ammonia ; by conducting cyanogen gas into
boiling hydriodic acid : —

CN CH2.NH2

I H-2H20 +2H2= I +NH3;

CN CO.OH

furthermore, by the action of zinc and hydrochloric acid upon
cyancarbonic ester (p. 377) in alcoholic solution : —
CN CH2.NH2

I +2H2+H20= I +C2H5.OH;

CO2.C2H5 CO2H

and finally, by letting ammonium cyanide and sulphuric acid act
upon glyoxal, CHO.CHO (p. 324), when the latter probably at first
yields formaldehyde, CH^O {Berichte, f5, 3087). Alanine is analo-
gously formed from acetaldehyde and ammonium cyanide.

In preparing glycocoll, pour 2 parts of concentrated sulphuric acid over finely
divided glue (i part), let stand several days, then add 8 parts of water and boil
for some time, with occasional addition of water to replace the evaporated steam.
Next, neutralize with chalk, filter and concentrate the filtrate. The glycocoll
obtained in this manner is crystallized from hot, dilute alcohol, to free it of any
adherent leucine.

37° ORGANIC CHEMISTRY.

A simpler procedure employs hippuric acid, CHj<^^„ '„' ^ (benzoyl gly-

cocoU). The latter is boiled with concentrated HCl (4 parts) for about one hour,
allowed to cool, the separated benzoic acid filtered off, and the filtrate concentrated.
The resulting glycocoll hydrochloride is boiled with water and lead oxide, the
lead chloride filtered off and the excess of Pb precipitated by H^S. In evaporat-
ing the filtered solution glycocoll crystallizes out.

Glycocoll is also obtained by warming monochloracetic acid with dry ammonium
carbonate [Berichte, 16, 2827).

It is most easily prepared by heating phthalylglycocoll ester, CjH^OjrN.CHj.
COj.C^Hj (from phthalimide and chloracetic ester), to 200° with hydrochloric acid
{Berichte, 22, 426).

Glycocoll crystallizes from water in large, rhombic prisms, which
are soluble in 4 parts of cold water. It is insoluble in alcohol and
ether. It possesses a sweetish taste, ^nd melts with decomposition
at 232-236°. Heated with baryta it breaks up into methylamine
and carbon dioxide ; nitrous acid converts it into glycollic acid.
Ferric chloride imparts an intense red coloration to glycocoll solu-
tions ; acids discharge this, but ammonia restores it.

Glycocoll yields the following compounds with hydrochloric acid : CjHjNOj.
HCI and 2(C2H5N02).HC1. The firstis obtained with an excess of hydrochloric
acid. It crystallizes in long prisms. The nitrate, CjHjNOj.HNOj, forms large
prisms.

An aqueous solution of glycocoll will dissolve many metallic oxides, forming
salts. Of these the copper salt, {C^^O^)^Q\x -\- HjO, is very characteristic.
It crystallizes in dark blue needles. 'Va.t silver salt, Q,^^O^h%, crystallizes
on standing over sulphuric acid. The combinations of glycocoll with salts, e. g.,
C2H5NO2.NO3K, CjHsNOj.NOsAg, are mostly crystalline.

The ethyl ester, CHj^^'^j-. ^ (Berichte, 17, 957), is an oil with an odor

resembling that of cacao, and boiling at 149°. It is very unstable and readily
becomes an anhydride (CH2(NH)CO)2 (Berichte, 16, 755). On leading HCl gas
into glycocoll and absolute alcohol, the HCl-salt is formed ; this melts at 144°.
The hydrochlorides of the methyl and propyl esters, etc. [Berichte, in, Ref. 253),
are produced in a similar manner.

Glycocoll Anhydride, (CH2.CO.NH)2 (?), forms upon evaporating glycocoll
ester with water. It crystallizes from hot water in large plates. When these are
rapidly heated they sublime in needles. If heated slowly, they become brown at
245° and melt at 275° (Berichte, 22, 793).

Glycocollamide, CH2<^f^Q |jtt , amidoacetamide, is produced when glycocoll

is heated with alcoholic ammonia to 160°. A white mass which dissolves readily
in water, and reacts strongly alkaline. The HCl-salt results on heating chloracetic
ester to 70° with alcoholic ammonia. y-Kt-a pir

Methyl-glycocoU, CjHjNOj = CHj^'^q ^^^3, Sarcosine, is obtained in

the action of methylamine upon monochloracetic acid (p. 368), and is also pro-
duced when creatine and caffeine are heated with baryta. It crystallizes in
rhombic prisms, which dissolve readily in water but with difficulty in alcohol. It
melts at 210-220°, decomposing into carbon dioxide and dimethylamine, yielding
at the same time an anhydride, (C3H5NO)2, which melts at 150° and boils at 350°

AMIDES OF THE DIHYDRIC ACIDS. 371

(Berichle, 17, 286) . It forms salts with acids ; these have an acid reaction. Ignited
with soda-lime it evolves methylamine. Nitrous acid changes it to the nitroso-

cooipound, CHjCf pi „ '' '. Sarcosine yields methylhydantoin with cyanogen
chloride. X^v-Zgn.

Triinethylglycocoll, C^i(^QQ^>, is betaine, described p. 316.

Ethyl-glycocoU, C^H^NO.^ = CH^cf ^q '^2^^ is obtained by heating mono-

chloracetic acid with ethylamine. It consists of deliquescent leaflets ; it unites
with acids, bases and salts, /-ksic ft N

Diethyl-glycocoll, ^^i\roh ''^i is derived from monochloracetic acid

and diethylamine. It consists of deliquescent crystals which sublime under 100°.

Aceto-glycocoU, CH^^^ ^-.q Vt^ ^ , aceturic acid, is obtained by the action

of acetyl chloride upon glycocoU silver, and of acetamide upon monochloracetic
acid. It consists of small needles, which dissolve readily in water and alcohol,
and char at 130°. It conducts itself like a monobasic acid. (Compare phenyl-
acetonic acid, Berichte, 21, Ref. 715.)

GlycocoU may be viewed as ammonia with one hydrogen atom replaced by the
monovalent groujj, — CHj.COjH. It is plain that two and three hydrogen atoms
in NH3 may be replaced by this group : —

/PH CCi H /CHj.CUjH
NH,.CH..C02H NH(^S:2-^X w N— CH^.CO^H

'Acid. D,gIycolam.d,c T>ig,y,^„,^„,?di<:

Acid.

These compounds are formed, together with glycocoU, on boiling monochloracetic
acid with concentrated aqueous ammonia. The solution is concentrated, filtered
off from the separated ammonium chloride, and boiled with lead oxide. On cool-
ing, the lead salt of triglycolamidic acid separates out, while glycocoU and lead
diglycolamidate remain dissolved. To remove the last compound, hydrogen sul-
phide is added to the solution, and the filtrate boiled with zinc carbonate. Zinc
diglycolamidate separates out, whUe glycocoU remains dissolved.

Di- and triglycolamidic acids are crystaUine compounds, forming salts with
bases and acids; the first is dibasic, the second tribasic. Diglycolamidic acid
yields a nitroso-compound with nitrous acid.

2. Amidopropionic Acids, CsHjNOj ^ C3H5(NH2)0.i.

(i) a-Amidopropionic Acid, CH3.CH(NH2).COjH, Alanine,
is derived from a-chlor- and brom-propionic acid by means of
ammonia, and from aldehyde ammonia by the action of CNH
and HCl (p. 367). Aggregated, hard needles, with a sweetish
taste. The acid dissolves in 5 parts of cold water and with more
difficulty in alcohol ; in ether it is insoluble. When heated it com-
mences to char about 237°, melts at 255° and then sublimes. It is

372 ORGANIC CHEMISTRY.

partially decomposed into ethylamine and carbon dioxide. Nitrous
acid converts it into a-lactic acid.

(z) /3Amidopropionic Acid, CH2(NH2).CH2.C02H, is obtained from ;8-iod-
propionic acid and ;3-nitropropionic acid (p. 224). It crystallizes in rhombic
prisms which dissolve readily in water. When heated it melts at 180° and sub-
limes with partial decomposition. Its copper compound is far more soluble than
that of the isomeric alanine.

3. Amidobutyric Acids, CjH,(NH2)02.

a-Amidobutyric Acid, CH3.CH2.CH(NHj).C02H, Propalanine, is obtained
from brombutyvic acid. It crystallizes in little leaflets or needles and is very
soluble in water.

/3-Amidobutyric Acid, CH,.CH(NH2).CH2.C02H, is apparently produced
when crolonic acid is heated with ammonia (p. 367).

7-Amidobutyric Acid, CH2(NH2).CH2JCH2.C02H, can be obtained from
phlhalimidetrimethylene cyanide {Berichte, Z2, 3337). It is very readily soluble
in water. It melts at 183°, and breaks down into water and pyrrolidon (p. 369).

K-Amidoisobutyric Acid, (CH3)2C(NH2).C02H, is made from acetonyl urea
on healing with hydrochloric acid, and is obtained from acetone by means of
CNH, Nllg and HCl (p. 367). It is also produced in the oxidation of diaceto-
namine with chromic acid • (together with amido-isovaleric acid, p. 208). It
ciystallizes in large rhombic plates, and sublimes without decomposition near 220°.

4. Amido-valeric Acids, C5Hg(NH2)02. — a-Amido-isovaleric Acid,
CH3.CH2.CH2CH(NH2).C02H, is formed on treating butyraldehyde with
hydrocyanic and hydrochloric acids. It consists of shining prisms, which sublime
without fusing. It is also produced by the oxidation of conine [Berichte, ig,
500).

y-Amidovaleric Acid, CH3.CH(NH2).CH2.CH2.CO,H, results from the
decomposition of phenyl hydrazone-lsevulinic acid (p. 343) by sodium amalgam
{Berichte, 22, i85o). It is crystalline, melts at 193° and forms an anhydride,
which is a pyrroline derivative. Boiling alkalies and baryta convert it again into
the acid.

(5-Amidovaleric Acid, CH2(NH2).(CH2)3.C02H (Homopiperidic Acid), is
produced when piperidine is oxidized. It forms shining leaflets; melts at 158°,
and breaks down into water and oxy-piperidine, CjHgONH. The latter is
resolved, by acids or alkalies, into the amido-acid. The latter is an indifferent
compound, but oxy-piperidine is a powerful poison (Berichte, 21, 2235).

a- Amido-isovaleric Acid, (CH3)2.CH.CH(NH2).C02H, Bu-
talanine, occurs in the pancreas of the ox, and is produced by the
action of ammonia upon bromisovaleric acid. It consists of shining
prisms which sublime without fusing. It dissolves with more diffi-
culty than leucine in water and alcohol.

^-Amido-isovaleric Acid, (,CH3)2C(NH2).CH2.C02H, is obtained by the
reduction of the nitro-acid (p. 228) ; Jt melts and sublimes at 215°.

DIAZO-ACIDS.

373

(S) a-Amido-caproic Acid, CH3.(CH2)3.CH(NH,).COjH,
Leucine, occurs in different animal juices, in the pancreas, and is
formed by the decay of albuminoids, or when they are boiled with
alkalies or acids. Artificial leucine prepared from bromcaproic
acid and valeric aldehyde appears to be an isomeride of the pre-
ceding.

Leucine crystallizes in shining leaflets, which have a fatty feel,
melt at 170° and sublime undecomposed when carefully heated.
Rapid heating breaks it up into amylamine and CO,. It is soluble
in 48 parts of water at 12° and in 800 parts of alcohol.

The leucines derived from different sources differ in their optical
behavior. The synthetic variety (from brom-caproic acid and
valeric aldehyde) is inactive. Penicillium glaucum causes this
variety to ferment, and it is then transformed into the Igevorotatory
variety. Boiling baryta water changes this again into the inactive.
Therefore, when albuminoids are decomposed by boiling baryta
water the product is inactive leucine. Active laevo-leucine results
if the decomposition be effected with hydrochloric acid {Berichte,
17. 1439 J 18, 2984).

Nitrous acid converts it into leucic acid (p. 364). Fused with potash it decom-
poses into ammonium and potassium valerates. When oxidized with lead peroxide
we get valeronitrile, CjHjj.CN.

DIAZO-ACIDS.

Acids of this class, like diazo-acetic acid, CHN2.CO2H, contain
the diazo-group N2 =, consisting of two nitrogen atoms, instead of
two hydrogen atoms. They are similar to the diazo-derivatives of
the aromatic series, but not wholly like them. When liberated from
their salts, by mineral acids, they immediately sustain decomposi-
tion. They are rather stable when existing as esters or amides.

The esters of the diazo-acids are obtained by the action of potas-
sium nitrite upon the hydrochlorides of the amido-fatty acid esters
(P- 370) (Curtius, 1883 ; Berichte, 16, 2230) : —
HCl.(H,N)CH,.CO,.C,H, 4- KNO, = CH(N2).CO,.C2H, + KCl + 2H,0.

Hydrochloride of Glycocoll Ester. Diazo-acetic Ester. .

The diazo-acids are very volatile, yellow-colored liquids, with peculiar odor.
They distil undecomposed with steam, or under reduced pressure. They are
slightly soluble in water, but mix readily with alcohol and ether. The hydrogen
of their CHN^-group can be replaced by alkali metals. This change may be
effected by the action of alcoholates. It shows that they possess a feeble acid
nature. Aqueous alkalies gradually saponify and dissolve them, with the forma-
tion of salts, CHNa.COjMe. Acids decompose these at once with the evolution
of nitrogen.

374 ORGANIC CHEMISTRY.

Ethyl Diazoacetate, CHNj.COj.CjHj, boils at 143-144° (under 120 mm.
pressure) ; its sp. gr. is 1.073 at 22°. When chilled it solidifies, forming a leafy,
crystalline mass, melting at — 24°. It explodes with violence when brought in
contact with concentrated sulphuric acid. A blow does not have this effect. Con-
centrated ammonia converts it into an amide, diazoacetamide, CHNj.CO.NHj,
that crystallizes from water and alcohol in golden-yellow plates or prisms. The
crystals become non transparent at 112°, and melt at 114° with decomposition.

The diazo compounds of the marsh gas series are especially reactive. They
split off nitrogen, and its place is taken either by two monovalent atoms or radicals.

The diazo-esters are converted, by boiling water or dilute acids, into esters of
the oxy- fatty acids (glycol acids) : —

CHN,.C0,.C,H5 + H,0 = CH,(OH).C02.C2H5 + N,.

Ester of Glycollic Acid.

This reaction can serve for the quantitative estimation of the nitrogen in diazo-
derivatives. Allcyl glycollic esters are produced on boiling with alcohols : —

CHN,.C0,.C3H, + C,H5.0H=CH,(O.C,H,).CO,.C2H5 -f N,;

a small quantity of aldehyde is produced at the same time.

Acid derivatives of the glycollic esters are obtained on heating the diazo-com-
pounds with organic acids : —

CHN,.C0,.C,H5 + C,H30.0H = CH,(O.C,H30).CO,.C,H5 + N^.
Acetic Acid. Aceto-glycollic Ester.

The haloid acids act, even in the cold, upon the diazo-compounds. The pro-
ducts are haloid fatty acids : —

CHN2.CO2.C2H5 + HCl = CH2CI.CO2.C2H5 + Nj.

The halogens produce esters of dihaloid fatty acids : —

CHN,.C0,.C,H5 + I, = CHI,.C0,.C,H5 + N,.
Di-iodo-acetic Ester.

Diazo-acetamide is changed, in a similar manner, to di-iodo-acetamide, CHI^.
CO.NH2. By titration with iodine it is possible to employ this reaction for the
quantitative estimation of diazo-fatty compounds {Berichte, 18, 1285).

The esters of the diazo-fatty acids unite with aldehydes to form esters of the
ketonic acids, e. ^., benzoylacetic ester, CjHj.CO.CHj.COjj.CjHj {Berichte, 18,
1 371). They produce peculiar acid esters by their union with the benzenes.
These compounds are isomeric with the esters of the phenyl fatty acids (^Berichte,
21, 2637) :—

C,H, -f CHN,.C0,.C2H, = C,H5.CH,.CO,.C,H5 + N,.

The diazoacetic esters and the esters of the unsaturated acids (acrylic, cinnamic,
fumaric) combine to additive products, which crystallize well : —

CH2 CHg^

II . +N2CH.C02R= I ^N^rCH.COjR.

RO2C.CH Diazoacetic Ester. ROjCCH/

Acrylic Ester. Acrylic-diazoacetic Ester.

On the application of heat nitrogen is split off, and an ester of trimethylene
carboxylic acid results : —

I ^NjiCH.CO^R = I )CH.CO,R.

ROj.C.CH/ ROjCCH/

Trimethylene-dicarboxylic Ester.

CARBONIC ACID AND DERIVATIVES. 375

In a similar manner cinnamic ester yields phenyl-trimethylene-dicarboxylic ester,
and fumaricesterjC2H2(C02R)2, trimethylene-tricarboxylic ester, C3H3.(C02R)3
(Berichte, 21, 2637; 23, 701). The compound with acetylene dicarboxylic ester
\Berichte, 22, 842) conducts itself differently.

The esters of anilido- fatty acids result from the union of the anilines with diazo-
esters. They revert to the amido-acids upon reduction (with zinc dust and glacial
acetic acid). Hydrazine-fatty acids are intermediate products. These are not
very stable [Berichte, 17, 9S7).

a-Diazo-propionic Ester, CHg.CNj.COj.CjHj, is similarly obtained from
the hydrochloride of alanine ethyl ester (p. 371). It is a yellow oil. It behaves
very much like diazo-acetic ester (Berichte, 22, Ref. 104) (see this). Diazosuc-
cinic acid is a dibasic diazo-acid.

Triazo Compounds.

Triazo - acetic Acid (Triazo - trimethylene - tricarboxylic acid), CjHjNg
(COjH),, is formed (as sodium salt) when com;entrated sodium hydroxide acts upon
diazo-acetic ester. It contains three molecules of water, and crystallizes in orange-
yellow, shining plates. When rapidly healed they melt at 152° (Berichte, 22,
Ref. 133). The acid is almost insoluble in cold water, ether and benzene, but
soluble in alcohol and glacial acetic acid. Its sodium salt is sparingly soluble.
The ethyl ester melts at 110°. Ammonia converts its ester into triazo-acetamide.
The acid is resolved into oxalic acid unA hydrazine [Berichte, 22, Ref. 134), when
digested with water or mineral acids : —

C3H3Ne(CO,H)3 + eH^O = sC^H^O, + sN^H,.

Consult t\itJour. pr. Chemie, 39, 107, upon the constitution of the diazo- and
triazo-derivatives {Berichte, 22, Ref. 196).

CARBONIC ACID AND DERIVATIVES.

r

The acid only exists in its salts (p. 353), and may be regarded
as oxyformic acid, HO. CO. OH. Its symmetrical structure distin-
guishes it, however, from the other oxy-acids containing three atoms
of oxygen. It is a weak dibasic acid and constitutes the transition
to the true dibasic dicarboxylic acids — hence it will be treated
separately.

Carbon Monoxide, CO, and Carbon Dioxide, CO2, the
anhydride of carbonic acid, have already received mention in
inorganic chemistry. Paper moistened with a solution of palla-
dious chloride is blackened by CO, hence it may be employed as a
reagent for this latter compound.

Carbonyl Chloride, C0C1„ Phosgene Gas, is formed by the
direct union of CO with Cl^ in sunlight (they combine very slowly
in diffused light) ; by conducting CO into boiling SbCIs, and by
oxidizing chloroform (2 parts) with a mixture of concentrated sul-
phuric acid (50 parts) and potassium bichromate (5 parts) :—

2CHCI3 -1- 3O = 2COCI2 -h HjO + CI 2.

376 ORGANIC CHEMISTRY.

The simplest course is to conduct CO and Clj over pulverized and cooled bone
charcoal (Patern6). Instead of condensing the gas it may be collected in cooled
benzene. To remove excess of chlorine the COClj is passed over heated anti-
mony.

Carbonyl chloride is a colorless gas with suffocating odor, and on
cooling is condensed to a liquid which boils at -\-8°. Water at once
breaks it up into CO^ and 2HCI.

When phosgene gas is allowed to act upon anhydrous alcohols,
the esters of chlorcarbonic acid are formed : —

COCI2 + C2H5.OH = Cq/q (, ^ + HCl.

They are more correctly termed esters of chlorformic acid,
CCIO.OH (p. 219). These are volatile, disagreeable-smelling
liquids, decomposable by water. When heated with anhydrous
alcohols they yield the neutral carbonic esters.

The methyl ester, CCIO.O.CH3, boils at 71.4°, the ethyl ester, CCIO^.C^H,,
at 94°, the propyl ester, at 115°, the isobutyl ester, at 128.8°, and the isoamyl
ester, at 154° (^Berichte, 13, 2417).

The amide of chlorcarbonic acid, CO;^ pi ^, called urea chloride, is produced

by. the interaction of phosgene gas and ammonium chloride at 400° {^Berichte, 20,
858; 21, Ref. 293) :—

COCI2 + NH3.HCI = CO(^^'jj + HCl.

It is a liquid with penetrating odor. It solidifies in needles, which melt at 50°
and boil at 6i°-62°, when it dissociates into hydrochloric aciji and isocyanic acid,
HCNO. The latter partly polymerizes to cyamelide. Urea chloride suffers a like
change on standing. Water or moist air decomposes it into carbon dioxide and
ammonium chloride. It reacts violently with amines, forming substituted ureas ; —

CO\NH, + CzHa-NH, = Cq/^H.C.H, ^ ^^^

With the benzenes and phenol ethers it yields acid amides: COCl.NHj -\- C^Hj
= C5H5.CO.NH2 + HCl {Berichte, 21, Ref. 214).

Alkyl Derivatives, Alkyl Urea Chlorides, ^^C'fiVlVJ ''^^"'' ^^°^ "^^ action
of COClj upon the HCl-amines at 250-270° C. [Berichte, 20, 118, 858; 21, Ref.
293) :—

C0CI2 + NH2.C2H5.HCi = cq/^'jj C H + ^^^'■

These are badly-smelling compounds boiling apparently without decomposi-
tion, yet they suffer dissociation into hydrochloric acid and isocyanic acid esters,

CO.NR, which reunite on cooling: CO.NR + HCl = CO(^^'jjg^. The reac-
tions of the alkyl urea chlorides are perfectly analogous to those of urea chloride
itself.

They are decomposed into COj and HClamines by water, and with amines

ETHYL CARBONIC ACID. 377

they yield alkylized ureas. They form carbamic and allophanic esters with alco-
hols {Berichte, 2l,Ref. 293). The benzenes convert them into alkylamides of
the carboxylic acids (see above). When distilled with lime they pass into isocy-
anic esters (see above). ,„,

Ethyl Urea Chloride, CO^' jjrx q^ „ , also obtained from ethylisocyanate and

hydrochloric acid, boils at 60-61°. Methyl Urea Chloride, CO^£L (,„ , crys-
tallizes in large leaflets, melts about 90° and boils with dissociation (see above) at

Dimethyl Urea Chloride, Co/q(*-'^3)2^ dimetliylcarbamic chloride (p. 384),

is produced by the action of dimethylamine upon COClj dissolved in benzene.
It boils at 150° C. Water decomposes it into CO2 and dimethylamine hydro-
chloride. /N(C H 1

Diethyl Urea Chloride, CO/pA ^ ^'''■, is obtained from diethyl oxamic acid,

(C2H5)2N.CO.C02H, by means of PCI5. It boils at 190-195°.

Ethyl Cyancarbonic Ester, CO('q'^„ „ , or cyanformic ester, is obtained

by distilling oxamic ester with V,^0^, or better with PCI5 : —

CO.NH2 CN

I -H,0= I

CO.O.CjHj CO.O.C2H5

It is a pungent-smelling liquid, boiling at 115-116°. It is insoluble in water,
but is gradually decomposed by the latter into COj, CNH and alcohol. Zinc and
hydrochloric acid convert it into glycocoll (p. 366). Concentrated hydrochloric
acid decomposes it into oxalic acid and ammonium chloride. Bromine or anhy-
drous HCl, at 100°, converts it into a crystalline, polymeric modification, melting
at 165°, and transformed by the action of alkalies in the cold into salts of para-
cyancarbonic acid, c. g., (CN.COjKjn.

The methyl ester, CN.CO^.CHj, boils at 100-101°.

The primary esters of carbonic acid are not stable in a free
condition. The potassium salt of Ethyl Carbonic Acid,

CO^ DTC ^ ^' separates in pearly scales on adding CO2 to the

alcoholic solution of potassium alcoholate. Water decomposes it
into potassium carbonate and alcohol.

The neutral esters appear when the alkyl iodides act on silver
carbonate : —

COjAg^ -I- 2C2HJ = CO^{C^YL^-)^ -I- 2AgI;

also by treating esters of chlorformic acid with alcohols, whereby
mixetl esters may also be obtained : —

C0<ScH3 + C3H.OH = C0/g;CfHa + HCl.

Methyl-ethyl Carbonate.

It is also true, that, with application of heat, the higher alcohols are able to ex-
pel the lower alcohols from the mixed esters : —

Kacb';^ + C^Ha.OH = C0(g:^3H= + CH3OH.
Methyl Ethyl Ester. Diethyl Ester.

32

378 ORGANIC CHEMISTRY.

Hence, to obtain the mixed ester, the reaction must occur at a lower temperature.

As regards the nature of the product, it is immaterial as to what order is pursued
in introducing the alkyl groups, i. c, whether proceeding from chlorformic ester,
we let ethyl alcohol act upon it, or reverse the case, letting methyl alcohol act
upon ethyl chlorformic ester ; the same methyl ethyl carbonic acid results in each
case [Berichte, 13, 2417). This is an additional confirmation of the like valence
of the carbon affinities, already proved by numerous experiments made with that
direct object (with the mixed ketones) in view.

The neutral carbonic esters are ethereal smelling liquids, insoluble
in water. Excepting ditnethyl and the methyl-ethyl ester, all are
lighter than water. With ammonia they first yield carbamic esters
and then urea. When they are heated with phosphorus pentachloride,
an alkyl group is eliminated, and in the case of the mixed esters this
is always the lower one, while the chlorformic esters constitute the
product : —

C0<8:cfl}, + PC'= = ^°\aC,H, + PClsO + CH.Cl.

Methyl Carbonic Ester, €03(0113)2, is produced from chlorformic ester
by heating with lead oxide. It boils at 91°- The methyl ethyl ester,

CO 3\c^ '^^^ ^' ^°^°' Theethyl ester, C03(C2H5)2, is obtained from ethyl
oxalate, QfiJ^C,^^)^, on warming with sodium or sodium ethylate (with evolu-
tion of CO2). It boils at 126°. The methyl propyl ester, C03(CH3)(C3H7), boils
at 130°.

Thi ethylene ^j/f?-, CO jCjH^, glycol carbonate, obtained from glycol and COClj,
melts at 39°, and boils at 236°.

Carbon mono-sulphide, analogous to carbon monoxide, is
unknown.

Carbon Oxysulphide, COS, occurs in some mineral springs,
and is formed in various ways, as, for example, by conducting sul-
phur vapor and carbon monoxide through red hot tubes. It is
most easily prepared by heating potassium thiocyanate with sulphuric
acid, diluted with an equal volume of water: CN.SH -(- HjO =
CSO + NHj {Berichte 20, 550).

In order to obtain it pure, conduct the gas into an alcoholic
potash solution, and decompose the separated potassium ethyl thio-

/ O C Ff
carbonate, CO' gjV '^ ^ (p. 382), with dilute hydrochloric acid.

Carbon oxysulphide is a colorless gas, with a faint and peculiar
odor. It unites readily, and forms an explosive mixture with air.
It is soluble in an equal volume of water. It is decomposed by the
alkalies according to the following equation : —

COS -I- 4KOH = CO3K2 -f KjS -I- 2H2O.

Thiocarbonyl Chloride, CSClj, is produced when chlorine acts upon carbon
disulphide, and when the latter is heated with PCL in closed tubes to 200° : CS,
-(- PCI5 = CSCl2 + PCI3S.

TRI-THIOCARBONIC ACID. 379

It is most readily obtained by reducing perchlormethylmercaptan, CSCI^ (p.
142), with stannous chloride, or tin and hydrochloric acid (Klason, Berichte, 20,
2380; Billeter, 21, 102) : —

CSCI4 + SnClj = CSCI2 + SnCl^.

This is the method employed for its production in large quantities.

It is a pungent, red-colored liquid, insoluble in water, and boiling at 73° ; its sp.
gr. is 1.508 at 15° On standing exposed to sunlight, it is converted into a poly-
meric, crystalline compound, C2S2CI4, = CI.CS.S.CCI3, methyl perchlor-dithio-
formate, which melts at 116°, and at 180° reverts to the liquid body (Berichte, 21,

337)-.

Thiocarbonyl chloride converts secondary amines (i molecule) into dialkyl
sulpho-carbamic chlorides (p. 386) : —

CSCl, + NH(C,H,)C,H, = CS(^1 (,^H,)C,H,-

A second molecule of the amine produces tetra-alkylic thioureas {Berichte, 7.^,102).

Carbon Disulphide, CS^, is obtained by conducting sulphur
vapor over ignited charcoal. It is a colorless liquid, with strong
refractive power, boils at 47°, and at 0° has a specific gravity of
1.297. It is obtained pure by distilling the commercial product
over mercury or mercuric chloride; its odor is then very faint.
It is almost insoluble in water, but mixes with alcohol and ether.
It serves as an excellent solvent for iodine, sulphur, phosphorus,
fatty oils and resins. In the cold it combines with water, yielding
the hydrate 2CS2 + H^O, which decomposes again at — 3°.

Carbon disulphide, in slight amount, is detected by its conversion into potassium
xanthate. This is accomplished by means of alcoholic potash. The copper salt
is obtained from the potassium compound. The production of the bright-red com-
pound of CS2 with triethyl phosphine (p. 169, and Berichte, 13, 1732) is a more
delicate test.

Dry chlorine gas converts CSj into sulphur monochloride and thiocarbonyl
chloride, CSCI2. By the addition of chlorine we obtain CSCl^ = CCI3.SCI, per-
chlormethyl mercaptan, a yellow liquid, which becomes CClj.SOjCI (p. 153) when
oxidized. Zinc and hydrochloric acid convert CSj into trithiomethylene (p. 193).

Carbon disulphide can be called the sulphanhydride of tri-thio-
carbonic acid, CS3H2. It is perfectly analogous to CO2, and unites
with metallic sulphides, forming tri-thiocarbonates.

Tri-thiocarbonic Acid, CSsH^^ CSQgjj. Hydrochloric acid

precipitates this as a reddish-brown, oily liquid, from solutions of its
alkali salts. The sodium salt, CSsNa,, separates in the form of a
thick, red liquid when alcohol and ether are added to a solution of
sodium sulphide containing carbon disulphide. This salt is readily
dissolved by water. The barium salt, CSgBa, is a yellow crystalline
powder, obtained by shaking aqueous BaS with CSj.

380 ORGANIC CHEMISTRY.

Ethyl Trithiocarbonate, CS^ S'p s^js formed when an alcoholic solution

of ethyl iodide acts upon sodium trithiocarbonate. It is a yellow oil,, insoluble in
water, and boils at 240°. It forms red-colored, crystalline derivatives with two
atoms of chlorine or bromine. These regenerafe the ether when treated with water.
The methyl ester, CS(S.CH3)2,boils at 204-205°. The action of ethylene bromide

upon the sodium salt yields the ethylene ester, CS^'g^CjH^; large, yellow crys-
tals, melting at 36.5°. These dissolve readily in ether, but with more difficulty in
alcohol. When oxidized with dilute nitric acid the ester becomes ethylene-dithiocar-
bonic ester, COS»:C„H,, which forms plates, melting at 31°.

Ethyl-trithiocarbonic Acid, CS<^ j-'tt^ ', is not known in a free condition.

,/S.C,H,

'\SH

The potassium salt, CS^ ^^ ^ '', is produced by the direct union of carbon -di-
sulphide, with potassium mercaptide, C^Hj.SK.

Dithiocarbonic acid, COSjHa, may have one of two formulas : —

p«/SH pq/SH

Dithiocarbonic Acid. Thiosulphocarbonic Acid.*

The free acids are not known ; dialkyl esters, however, do exist.
Thiosulphocarbonic acid is capable of forming esters or ether acids

of the type CS^ oVt ^ ^ called xanthic acids : —

Methyl Xanthate. Ethyl Xanthic Acid.

The esters oi dithiocarbonic acid, C0(SH)2, result when COCl^ acts upon the
mercaptides : —

COClj + 2C2H5.SK = COCS.CaHs)^ -f 2KCI;

and when thiocyanic esters (p. 278J are heated wilh concentrated sulphuric
acid : —

2CN.S.CH3 + 3H2O = CO(S.CH3)2 -\- CO2 + 2NH5.

They are liquids with garlicky odor. Alcoholic ammonia decomposes them
into urea and mercaptans : —

CO(S.C,H,), -f 2NH3 = Co/^g^ -f 2C,H,.SH.

The methyl ester, CO(S.CH3)2, boils at 169° ; the ethyl ester, CO(S.C2H5)2,
at 196°.

, * To distinguish the isomerides the sulphur joined with two valences to carbon
is called sulpho-, the monovalent sulphur, thio.

THIOCARBONIC ACID. 38 1

The xanthates, R.O.CS.SM', are produced by the combined
action of CS^ and caustic alkalies in alcoholic solutions : —

CS, + KOH + CH3.OH = CS^gj^^s + HjO.

Potassium Methylxanthate.

Cupric salts precipitate yellow copper salts from solutions of the
alkaline xanthates. By the action of alkyl iodides upon the salts
we obtain the esters : —

Ethyl-methyl Xanthic Ester.

The latter are liquids, not soluble in water. Ammonia breaks
them up into mercaptans and esters of sulphocarbamic acid (p.
385):-

C<s:§h: + NH, = CS(0C.H5 + c,H,SH.

With alkali alcoholates, mercaptan and alcohol separate, and
salts of the alkyl thiocarbonic acids (p. 382) are formed (^Berichte,

13.530):— t

C<S.§h; + CHs-OK + H,0 = WH ^ coQ^^.

Xanthic Acid, or ethyl oxydithiocarbonic acid, CjHj.O.CS.SH. A heavy
liquid, not soluble in water. It decomposes at 25° into alcohol and CSj.

Potassium Xanlhate, C^Hj.O.CS.SK, forms on mixing alcoholic potash with
carbon disulphide. It consists of silky needles, which dissolve very readily' in
water, and are quite insoluble in alcohol. The salts of the heavy metals are in-
soluble in water, and are obtained from the potassium salt by double decomposition.
The copper salt is yellow ; it decomposes on drying.
S.CS O.C2H5

Xanthic Disulphide, | , is produced on adding an alcoholic solu-

S.CS.O.C2H5
tion of iodine to the potassium salt (p. 251). Insoluble, shining needles, melting
at 28°-

When ethyl chloride acts upon potassium xanthate, we get the ethyl ester,
C2H5.O.CS.S.C2H5, a colorless oil, boiling at 200°.

The remaining alkyl oxydithiocarbonic acids are perfectly similar to xanthic
acid. Ethyl-methyl xanthic ester, CH.O.CS.S.C2H5, and methyl xanthic ester,
C2H5.O.CS.S.CH3, both boil at 184°. They are distinguished by their behavior
toward ammonia and sodium alcoholate (see above).

Carbonic acid, containing one sulphur atom, may exist in two
isomeric forms (p. 380) : —

CS<OH and Co/gH

Sulphocarbonic Thiocarbonic

Acid. Acid.

382 organic' CHEMISTRY.

Both acids are incapable of existing free, but they yield isomeric
dialkyl esters. Thiocarbonic acid can, like xanthic acid, yield

ether-thiocarbonates of the type, CO(^?J^' ^

Sulphocarbonic Acid. Its ethyl ester, CS(O.C2H5)2, is produced by the
action of sodium alcoholate upon thiocarbonyl chloride, CSClj, and in the dis-
tillation of 32(05.0.02115)2 (see above). It is an ethereal smelling liquid, boil-
ing at 161-162°. With alcoholic ammonia the ester decomposes into alcohol and
ammonium thiocyanate, CN.S.NH4; alcoholic potash converts it into alcohol and
potassium ethyl thiocarbonate. .„ „ „

Ethyl Thiocarbonic Acid. 'V\is potassium salt, COj^g^^^s^ is obtained

from xanthic esters and alcoholic potash (p. 381), and in the union of carbon
dioxide with potassium mercaptide, CjHj.SK. It crystallizes in needles and
prisms, which readily dissolve in water and alcohol. With ethyl iodide the potas-

slum salt forms ethyl thioxycarbonate, COy c'p^u*; which can be prepared

from chlorcarbonic ester, CGCl.O.CjHj, and sodium mercaptide. It boils at 156°.
Alkalies decompose it into carbonate, alcohol and mercaptan. Such esters can
also be prepared by acting upon the zinc mercaptides with esters of chlorcarbonic
acid {Berichte, 19, 1228).

AMIDE DERIVATIVES OF CARBONIC ACID.

Carbonic acid is dibasic, and forms amide derivatives similar to
those of the dibasic dicarboxylic acids : —

^q/NH2 C0/NH2

Carbamic Acid. Carbamide.

HN:C(^^|[][ CO = NH:

Imido-carbonic Acid. Carbimide.

Carbamic Acid, H^N.CO.OH, Amidoformic Acid, is not
known in a free state. It seems its ammonium salt is contained in
commercial ammonium carbonate, and is prepared by the direct
union of two molecules of ammonia with carbon dioxide. It is a
white mass which breaks up at 60° into 2NH3 and COj, but these
combine again upon cooling. Salts of the earth and heavy metals
do not precipitate the aqueous solution j it is only after warming
that carbonates separate, when the carbamate has absorbed water
and becomes ammonium carbonate. When ammonium carbamate
is heated to 130-140° in sealed tubes, water is withdrawn and urea,
CO(NH2)2, formed.

The esters of carbamic acid are called ur ethanes ; these are
obtained by the action of ammonia at ordinary temperatures upon
carbonic esters : — <

C<a8:H: + NH3 = C0(NH^^jj^ + C2H,.0H;

AMIDE DERIVATIVES OF CARBONIC ACID. 383

and in the same manner from the esters of chlorcarbonic and cyan-
carbonic acids : —

CO<Sc,H, + NH3 = C0(NH,^^ ^ HCl,

■ CO\8!^,H, + ^NH3 = C0(NH.^^ + CN.NH,.

Also by conducting cyanchloride into the alcohols : —

CNCl + 2C2H5.OH = CO^^p V + C^H.Cl;

and by the direct union of cyanic acid with the alcohols : —

CO.NH + C^Hs.OH = C0/q^2jj .

When there is an excess of cyanic acid employed, allophanic esters are also pro-
duced.

The urethanes are crystalline, volatile bodies, soluble in alcohol, ether and water.
Alkalies decompose them into COj, ammonia and alcohols. They yield urea when
heated with ammonia ; —

CO<0.?:h, + NH3 = C0(NH^^ + C,H,OH.

Conversely, on heating urea or its nitrate with alcohols, the urethanes are re-
generated. „jj

Methyl Carbamic Ester, C0(' q ^fp , methyl urethane, crystallizes m

plates, which melt at 52°, and boil at 177°. The ethyl ester, CO(NH2).O.C2H5,
also called urethane, consists of large plates, which melt at 47-50°, and boil at
180°. The propyl ester melts at 53°, and boils at 195°- The isoamyl ester ctjs-
tallizes from water in silky needles, which melt at 60°, and boil at 220°. The allyl
ester, CO(NH2).O.C3H5, is a solid, melting at 21°, and boiling at 204°.

Alcohol radicals can replace the hydrogen of NHj in carbamic
acid. The esters of these alkylized carbamic acids are formed, like
the urethanes, by the action of carbonic or chlorcarbonic esters
upon amines; and on heating isocyanic esters (p. 274) with the
alcohols to 100° : —

CO:N.C,H, + C,H,.OH =Co(^^^^^^;

also, by the interaction of the chlorides of alkyl urea and the alco-
hols:—

CO<NHR + C,H,.OH= C0(0-Cf a + HCl.

Methyl Etho-carbamic Ester, CHj.HN.CO.O.CjH,, boils at 170°.
Ethyl Etho-carbamic Ester, (C3H5)HN.CO.O.C2H5, boils at 175°.

384 ORGANIC CHEMISTRY.

Derivatives of carbamic acid with divalent radicals are produced by the union of
esters of the acid with aldehydes : —

Ethidene Urethane, CH3.CH(HN.CO.O.C2H5)2, from urethane and acetal-
dehyde, crystallizes in shining needles, melting at 126° C.

Chloral Urethane, CCl3.CH.(f tt-t ^^^ ^ ^ „ , from urethane and chloral,
melts at io^° \H.iN.(^U.U. 1^2^15

Ulcus at luj . /NHCN

Cyanamido-carbonic Acid, CO^" qtt' , Cyancarbamic acid. Its salts

are formed by the addition of CO^ to salts of cyanamide : —

2CN.NHNa + CO^ = Co/q|^^)-^^ + CN.NH^.

The esters of this acid result by the action of alcoholic potash upon esters of cyan-

amidodicarbonic acid, CN.N^' (-.q'^^tt^. The latter are produced by allowing

the esters of chlorcarbonic acid to react with sodium cyanamide i^Jour. pr. Chem.,

16,146). The <r,4/on(i5? of carbamic acid, C0(' p. '', has been described as the

amide of chlorcarbonic acid (p. 376). Its alkylic derivatives, or alkyl urea chlor-
ides (p. 376) may also be termed alkyl carbamic acid chlorides.

Imido-carbonic Acid, HNiC^' (-.rr.

The esters of this acid are obtained by reducing the esters of <chlorimido-car-
bonic acid (see above) with potassium arsenite. They are alkaline liquids, with am-
moniacal odor, miscible with water, and again separated upon the addition of caustic
alkalici. They are very unstable, distil with decomposition, and are decomposed
by acids into ammonia and esters of carbonic acid. They give off the odor of car-
bylamine, CN.CjH^, when heated with zinc dust. They unite with amide deriva-
tives and at the same titne split off the imide group.

Their combinations with orthophenylene-diamines and ortho-amido-phenols (Be-
richte, ig, 862 and 2650) are quite interesting. ,„ (-, tt

The esters of Chlorimido-carbonic Acid, C1N:C(^ q p^tr^i ^^2 produced in the

action of esters of hypochlorous acid (p. 155) upon a concentrated potassium cya-
nide solution. They are solids, with a peculiar penetrating odor, and distil with
decomposition. Alkalies have little effect upon them, while acids break them up
quite easily, forming ammonia, esters of carbonic acid and nitrogen chloride.

The ethyl ester, C1N:C(0.C2H5)2, melts at 39°, and the methyl ester, C1N:C
{O.C3H,)2,at2o°. „j^

The c,4/oW<fi?j of dialkylic sulpho-carbamic acids, CS^ ™ 2, are produced by

the action of thiophosgene upon secondary amines (p. 378).

Cyanic acid (p. 271) is probably the imide of carbonic acid —
Carbimide, CO:NH.

AMIDE DERIVATIVES OF CARBONIC ACID. 385

Perfectly analogous amides are derived from the thio-carbonic acids.

Dithiocarbamic Acid, CS(^ ojt ^, is a reddish oil, obtained by decomposing

the ammonium salt with dilute sulphuric acid. It breaks up very readily into thio-
cyanic acid and hydrogen sulphide : —

Cs/?^2 ^ CN.SH H- SH,.
\0ri2

Water decomposes it into cyanic acid and 2SH2. The ammonium salt
CS^ o ^|t , forms yellow needles or prisms, and is produced in the action oi

alcoholic ammonia upon CSj.

By heating this salt together with aldehyde we obtain the compound, H^N.CS.
S.N (CH3.CH)2 = C5H,|,S2N2, carbothialdine. This is also obtained on
mixing CSj with alcoholic aldehyde-ammonia [Berichte, 11, 1384). It consists of
large, shining crystals, and when boiled with acids decomposes into ammonia,
carbon disulphide and aldehyde.

The dithiourethanes are the esters of the above acid. They arise when the
thiocyanic esters are heated with H 2 S (compare phenyl dithiocarbamic acid) : — ■

CN.S.C2H5 + HjS = Cs/g ^2^

They are crystalline compounds, soluble in alcohol and ether, and are decom-
posed into ammonium thiocyanate and mercaptans, when treated with alcoholic
ammonia.

The eikyl ester melts at 41-42° and the propyl ester at 97°. Both crystallize in
shining leaflets.

Alkyls may replace hydrogen of NHj in dithiocarbamic acid. The amine
salts of these compounds are obtained on heating CSj with alcoholic solutions of
the primary and secondary amines : —

Ubj -t- 21^2«5-J-^^i2 — ^°\S(NH3.C2H5)-

Boiling aqueous soda eliminates ethylamine from this salt and produces sodium

ethyl dithiocarbamic acid, CS^ gjj ' ^ *. The free acid obtained from this is

an oil which solidifies to a crystalline mass. When its amine salts are heated to
110°, dialkylic thio- ureas are produced (p. 395) : —

„„ /NH.C2H, _ „g/NH.C2H5 g

<^S \S.(NH3.C2H5) - ^^\NH.C2H, + "^^-

Diethyl Sulphocarbaraide.

If the aqueous solution of the salts obtained from the primary amines be digested
with metallic salts, e.g., AgNO,, FeClj or HgClj, salts of ethyl-dithiocarbamic
acid are precipitated : —

C<^(S-Sfc:H,) + ^gN03 = CS<NH-^.H, ^ (NH3.C2H,)N03.
These yield the mustard oils when boiled with water (p. 279) :—

2CS<^sS'^'"' = 2CS:N.C2H, + Ag^S + SH2.

The salts obtained from the secondary amines do not yield mustard oils
{Berichte, 8, 107).

386 ORGANIC CHEMISTRY.

Monosulphur carbamic acid can occur in two isomeric forms in its esters : —

Sulphocarbamic Ester. Thiocarbamic Ester.*

(1) The esters of sulphocarbamic acid — thiourethanes — are formed when
alcoholic ammonia acts upon the xanthic esters (p. 381) : — .

They are crystalline compounds, which decompose into mercaptans, cyanic acid
and cyanuric acid on heating. Alcoholic alkalies decompose them into alcohols
and thiocyanates, CNSK.

The ethyl ester of sulphocarbamic acid is slightly soluble in water and melts at
38°. '^\i& methyl ester ^€i.\s.3X./^l°.

The esters of alkylic sulphocarbamic acids are obtained when the mustard oils
are heated to 1 10° with anhydrous alcohols : —

CS:N.C,H5 + C^Hs.OH = CS^^^-^^^^

They are liquids with an odor like that of leeks, boil without decomposition and
break up into alcohols, CO2, HjS and alkylamines, when acted upon with alkalies
or acids.

Ethyl Etho-sulphocarhamic Ester, C2H5.NH.CS.O.C2H5, boils at 204-208°.
Allyl sulphocarbamic ester, C3H5.NH.CS.O.C2H5, from allyl mustard oil, boils at
210-215°.

(2) The esters of thiocarbamic acid are obtained by conducting hydrochloric
acid gas into a solution of CNSK (or of alkyl sulphocyanates, Berichte, 19, 1083)
in alcohols (together with esters of sulphocarbamic acid — Joum. pract. Chem.,
16, 358) ; and by the action of ammonia upon the dithiocarbonic esters,
CO(S.C2H5)j, and chlorthioformic esters : —

CO<S.C,H, + ^NHs = CO(f §H, + NHP.

These are crystalline compounds, which are dissolved with difficulty in water,
and decompose when heated.

The methyl ester, NHj.CO.S.CHj, melts at 95-98°- The ethyl ester melts at

I08°(lO2°). ,j^jj

Ammonium Thiocarbonate, CO^ c »t|t , is prepared by leading COS into

alcoholic ammonia. It is a colorless, crystalline mass, which acquires a yellow
color on exposure to the air, owing to the formation of ammonium sulphide. When
heated to 130° it breaks up into hydrogen sulphide and urea.

Carbamide, Urea, CH^N^O = C0('^}|^

This was discovered in urine in 1773, and was first synthesized
by Wohler in 1828. It occurs in various animal fluids, chiefly in

* Imidothiocarbonic acid, HN:C(f <,„ , is isomeric with these acids. It is only
known in its phenyl derivatives (see phenyl isothiourethane) .

CARBAMIDK — UREA. 387

the urine of mammals, birds, and some reptiles. It may be pre-
pared artificially in various ways: (i) by evaporating the aqueous
solution of ammonium isocyanate, when an atomic transposition
occurs (Wohler) : —

COiN.NHj yields CO^SS^ ;
• \iNnj

(2) by the action of ammonia upon carbonyl chloride or carbonic
esters : —

COCI2 + 2NH, = C0<^^g2 + 2HCI,

(3) by heating ammonium carbamate or thiocarbamate to 130-
140° :—

It is further produced in the action of alkalies upon creatine and
allanto'in ; in the oxidation of uric acid, guanine and xanthine, and
when small quantities of acids act upon cyanamide (p. 288): —

CN.NH^ + H,0 = COc^^g^.

Preparation from Urine. Urine is evaporated to a. thick syrup, and when
cool concentrated nitric acid (or, better, oxalic acid) is poured over it. The sepa-
rated, brown-colored nitrate is repeatedly crystallized from dilute nitric acid, in
order to obtain it pure ; it is then dissolved in water, heated with barium carbonate,
and the filtrate evaporated to dryness. The urea is extracted from the residue with
absolute alcohol.

The best synthetic method is its preparation from ammonium cyanate. Mixed
aqueous solutions of potassium cyanate and ammonium sulphate (in equivalent
quantities) are evaporated; on cooling potassium sulphate crystallizes out. and is
filtered off, the filtrate being evaporated to dryness, and the urea extracted by means
of hot alcohol. The following gives good practical results : 28 parts of anhydrous
yellow prussiate of potash are fused with 14 parts of manganese dioxide. The
fused mass is dissolved in water, 20^ parts of ammonium sulphate are added, and
the entire solution is then evaporated to dryness. The urea is extracted from the
residue with alcohol.

The easiest course to pursue in order to obtain the urea is to conduct ammonia
into fused phenyl carbonate, 00(0.05115)2 {Berickte, 17, 1286).

Urea crystallizes in long, rhombic prisms or needles, which have
a cooKng taste, like that of saltpetre. It dissolves in i part of cold
water and in 5 parts of alcohol ; it is almost insoluble in ether. It
melts at 132°, and above that temperature breaks up into ammonia,
ammelide, biuret and cyanuric acid. When urea is heated above
100° with water, or when boiled with alkalies or acids, it decom-
poses into its constituents : —

COiN^H, -H HjO = CO2 -f 2NH3.

388 ORGANIC CHEMISTRY.

Nitrous acid decomposes urea, in the same manner that it decom-
poses all other amides : —

<^°\NH, + ^A = CO, + 2N, + 2H,0.

Urea, like glycocoll, forms crystalline compounds with acids, bases and salts.
Although it is a diamide it combines with but one equivalent of acid (one of the
amido-groups is neutralized by the carbonyl group).

Urea Nitrate, CH^N^O.HNOj, crystallizes in shining leaflets, which are not
very soluble in nitric acid. The HCl-salt, CH^NjO.HCl, is formed when dry
HCl-gas is conducted over urea; it is a yellow oil, decomposing on exposure to
the air. The oxalate, {QM.^^)^^^^ -f "2H2O, is precipitated by oxalic
acid from an aqueous solution of urea in the form of thin leaflets, which are not
readily soluble in water.

The compound with mercuric oxide, CH^N20.2HgO, is a white precipitate,
obtained on adding potassium hydroxide and mercuric nitrate, Hg(NOj)2,to a
urea solution. Mercuric chloride produces a white precipitate, which assumes a
yellow color when washed with water, and has then the composition expressed by
the formula, CH^NjO.sHgO. Silver oxide yields a crystalline, gray compound,
(CH.N^Oj^.sAg^O.

On evaporating a solution containing both urea and sodium chloride, the com-
pound, CH^NjO.NaCl + HjO, separates in shining prisms. Large rhombic
prisms of CH^NjO.AgNOj crystallize from a concentrated solution of urea and
silver nitrate.

Mercuric nitrate precipitates compounds of variable composition from aqueous
urea ; a volumetric method for estimating the latter is founded on this fact.

Isuretine, CH;^ jj ^„, is isomeric with urea : it is produced by the direct
union of hydroxylamine, NH3O, with CNH (p. 294).

Hydroxy-urea, Q,0\^ ^tt' , is obtained by mixing aqueous

hydroxylamine nitrate with potassium isocyanate. It is readily
soluble in water and alcohol, but is thrown out of these solutions in
rhombic leaflets by ether. .It melts at 128-130°.

COMPOUND UREAS.

By this term we designate all compounds derived from urea by
the replacement of hydrogen in the amido-groups by alcofeol or
acid radicals.

I. Alkylic ureas are produced according to the same reactions
which yield urea, substituting, however, amine bases for ammonia
or isocyanic esters for cyanic acid : —

COiNH + NH^.C^H^ = Co/^g-^^2^5,

Ethyl Urea.

COMPOUND UREAS. 389

CO:N.C,H, + NH,.CH3 = Cq/^H.C^Hs.

Methyl-ethyl Urea.

CO:N.C,H, + NH(C,H,), = Co/^H.C^H,^_

Triethyl Urea.

This is the reaction with the primary and secondary amines, but
not with the tertiary amines.

Alkylic ureas are formed, too, when isocyanic esters are heated
with water — COj, and amines being produced ; the latter unite with
the esters : —

COiN.CjHj + HjO = NH2.C2H5 + CO2 and

CO:N.C,H, + NH,.C,H, = 00^^^;^^^^

They are also obtained by the action of urea chloride and alkyl-
urea chlorides (p. 376) upon amines : —

C0(^i^2 + NH,.C,H, = CO/NH,^^^^ ^ jjCl,

CO/NHR ^ NH,R = CO/NHR ^_ jjCl.

Ureas of this class are perfectly analogous to ordinary urea so far
as properties and reactions are concerned. They generally form
salts with one equivalent of acid. They are crystalline salts, with
the exception of those containing four alkyl groups. On heating
those with one alkyl group, cyanic acid (or cyanuric acid) and an
amine are produced. The higher alkylized members can be dis-
tilled without decomposition. Boiling alkalies convert them all
into CO2 and amines : —

CO/^H^"' + H,0 = CO, + NH, + NH^.CH,.

Methyl Urea, CO^i,jrT' ', results on heating methyl aceto-urea (from aceta-
\JNrl2
mide by the action of bromine and caustic potash, p. 391 and Berichte, 15, 409)
with potassium hydroxide (^Berichte, 14, 2734). It consists of prisms melting at
102°. Sodium nitrite converts its nitrate into nitroso-methyl urea, CO(NH2).
N(NO).CH3. By reduction this yields methylhydrazine (p. 167).

Ethyl Urea, C0(^^5^^ S forms large prisms,' melting at 92°. They dis-
\JNrl2
solve readily in water and alcohol. Nitric acid does not throw them out of aque-
ous solution. /NH C H

o-Diethyl Urea, CO^^i^S'p 5^, crystallizes in long prisms, melting at 112°,

and boiling undecomposed at 263°. Nitrous acid (or KNOj upon the sulphate)

changes it to nitrosodielhyl urea, ^'^'C^i^q^ q -^ ■ This is a yellow oil, that

solidifies on cooling, and melts at -f S° By reduction, it yields an amido-deriva-
tive, which breaks up into CO^, ethylamine, and ethyl hydrazine (p. 167).

390 ORGANIC CHEMISTRY.

^-Diethyl \JiesL,(^L,i^ H 1 ' '^ f°'""6<i when potassium cyanate acts upon
diethylamine sulphate. Colorless crystals, melting at 70°.

Triethyl Urea, Co/^7^^^^,5 , melts at 63°, and distils at 223° ; it is very
soluble in water, alcohol and ether.

Tetraethyl Urea, COcf^tJvQ^S^K is produced on conducting COClj into a
solution of diethylamine in benzene : —

COCl, + 2NH(C,H,), = Co/^jg^Js). + 2HCI.

This liquid boils at 210-215°, and has an odor resembling that of peppermint.
It is soluble in acids, but is reprecipitated by alkalies.

Allyl Urea, C0(' -hjtt' ' ^, is obtained from allyl cyanic ester and ammonia,
or from allylamine sulphate and potassium cyanate. It consists of beautiful prisms,
melting at 85°. /NH C H

Diallyl Urea, CO^jru ,-.'tt*, Sinapoline, is formed when allyl isocyanic

ester is heated with water (p. 389) : —

2CO:N.C3H5 + H,0 = CQ/^gl^aHs + cO,;

or by heating mustard oil with water and lead oxide. Diallyl-thio-urea is first
formed, but the lead oxide desulphurizes it (p. 395). Diallyl-urea crystallizes in
large, brilliant leaflets, melting at 100°. They do not dissolve readily in water,
and have an alkaline reaction.

Ethylene Urea, C0:^tJ5 yC^Hj, is produced on heating ethyl carbonate to

i8o°,together with ethylene-diamine. Needles, melting at 131°, and readilysolu-
ble in both water and hot alcohol.
(.q/NH,

Ethylene Diurea, ^-ntw y*--2H4> '^ produced upon heating ethylene dia-

mine hydrochloride with silver cyanate. It dissolves with [difficulty in alcohol,
but readily in hot water. It melts at 192°, with decomposition.
Ethylated ethylene ureas are similarly formed : —

„o/NH.C,H, CO/'^^^

^^\NHC,H5 . "-"\NH,

From Cyanic Ester and From Cyanic Acid and

Ethylene Diamine. Dietliyl Ethylene Diamine.

Derivatives of urea with aldehyde radicals exist. They are produced at ordi-
nary temperatures by the union of urea with aldehydes ; water is eliminated [Ber-
ichte, 22, Ref. 579)- yNH\

Methylene Urea, C0(' \,„ ^CHj, is formed from urea and concentrated

formic aldehyde. White, granular crystals.

Ethidene Urea, C0<^Sj;^CH.CH3,is not very soluble in water, and melts

at 154°. Chloral Urea, CO(NH)2:CH.CCl3, crystallizes in leaflets, which melt
at 150° with decomposition.

When boiled with water these compounds break up into aldehydes and urea.

GLYCOLYL UREA. 39 1

CHj— O ^ CHj— O .

Ethylene.pseudo(iso)-Urea, I ,C:NH, or 1 >C.NH„, is

CH2— NH^ CHj— N^

isomeric with ethylene urea. It is a derivative of hypothetical iso- or pseudo-urea,

HO.C(f j^jj2 (compare isothiourea (p. 394), and ethylene pseudo-thioiirea (p. 396).

It is produced by the action of brom-ethylamine hydrobromide (p. 163) upon
potassium cyanate. It is a basic oil, which solidifies with difficulty [Berichte, 22,
1451).

Propylene-pseudo Urea, CjHjiCONjHj, is quite analogous. It results from
HBr-propylamine and potassium cyanate, as well as from allyl urea, by a molecu
lar rearrangement induced by hydrobromic acid (Berichte, 22, 2990).

2. DERIVATIVES OF UREA WITH ACID RADICALS, OR UREIDES.

The derivatives of the monobasic acids are obtained in the action
of acid chlorides or acid anhydrides upon urea. By this procedure,
however, it is possible to introduce but one radical. The com-
pounds are solids ; they decompose when heat is applied to them,
and do not form salts with acids. Alkalies cause them to separate
into their components.

Acetyl Urea, CO^ •j^tt' ^ * , is not very soluble in cold water and alcohol.

It forms long, silky needles, which melt at 1 1 2°. Heat breaks it up into acetamide
and isocyanuric acid. Chloracetyl urea, HjN CO.NH.CO.CHjCl, from urea and
chloracetyl chloride, crystallizes in fine needles, which decompose about 160°.
Bromacetyl urea dissolves with difficulty in water. When heated with ammonia
it changes to hydantoin (see above).

Methyl Acetyl Urea, CO<^ NFT CH ' ' ^^ obtained from methyl urea upon

digesting it with acetic anhydride, and by the action of bromine and potassium
hydroxide upon acetamide (p. 160). It dissolves very readily in hot water, crys-
tallizes in large prisms and melts at i8o°-

Diacetyl Urea, CO(^ tjit Vh^O' '^^"'''^ when COClj acts on acetamide,
NHj.CjHjO, and sublimes in needles without decomposition.

Derivatives of Urea with Divalent Acids : —
Glycolyl Urea, C3H4N2O2, Hydantoin, is produced by heat-
ing bromacetyl urea with alcoholic ammonia : —

C0/NH.C0.CH,Br _ CO/'"''- 1° +HBr;
\^"2 \nH.CHj

and from allantoin, and from alloxan'ic acid by heating with hydri-
odic acid. It crystallizes from hot water and alcohol, in needles,
which melt at 216°, and show a neutral reaction. When boiled
with baryta water, it passes into glycoluric acid : —

.NH.CO .NHj

Co/ I + H^O = C0(

\nh.ch, \nh.ch,co.oh.

Glycolyl Urea, Glycoluric Acid.

392 ORGANIC CHEMISTRY.

Nitrohydantoin, 03H3(N02)N202, is produced when very strong nitric acid
acts upon hydantoin. It melts at 170°. The alkyl hydantoins react in like
manner (Berickte, 21, 2320; 22, Ref. 58).

Glycoluric Acid, CjHgNjOj, Hydantoic Acid, was originally obtained from
uric acid derivatives (allantoin, glyco-uril, hydantoin), but may be synthesized by
heating urea with glycocoU, to 120° : —

or by digesting glycocoU sulphate with potassium isocyanate : —

CO:NH + NH,CH,CO,H = Co(NH^cH,CO,H.

Hydantoic acid is very soluble in hot water and alcohol. It crystallizes in large,
rhombic prisms. It is a monobasic acid, whose salts are generally very readily
soluble ; when heated with hydriodic acid they yield COj.NH, and glycocoU.

Hydantoin contains a closed or ring-shaped nucleus of five members, consisting
of three C-atoms and two nitrogen atoms. In this respect it resembles the glyox-
alines or imido-azoles. The hydantoin ring is, however, not very stable, owing
to the presence of two CO-groups. The alkylic hydantoins are derived by the
replacement of the hydrogen atoms of the CHj- and the two NH-groups. They
are known as a-, /3- and /-derivatives, and are represented as follows :^

/NH.CHj
C0( I .

^NH.CO

V

The ra-derivatives may be synthesized by heating the cyanhydrins of the aldehydes
and ketones (p. 203) with lu'ea (see a-phenyl-hydantoin, and Berickte, 21,
2320) : —

,CN /CO.NH

R.CH( + H.N.CO.NH, = R.CH<; | + NH3.

\0H ^NH.CO

a-Alkyl-hydantoin.

/3-Methyl-hydantoin, C3H3(CH3)N202, was first obtained from creatinine,
and is also formed when sarcosine (p. 370) is heated with urea : —

NH, N(CH3).CH2

)( + NH(CH3).CH2 = CO( I

^NH, I \nH . CO

CO,H

CO(f ^ + NH(CH3).CH2 = Cq/ ' °' I ' + ^Hj + H^O,

or by heating the sarcosine with cyanogen chloride {^Berickte, 15, 211). It forms
soluble prisms which melt at 157°, and sublime in shining needles. It forms
metallic derivatives on boiling with silver or mercury oxide, when the hydrogen of
the imid-group suffers replacement.

/3-Ethyl-hydantoin, CjH3(C2H5)N202. It is formed like the preceding,
and crystallizes in rhombic plates which melt at 100° and sublime readily.

a-Lactyl Urea, C4H3N2O2, a-Methyl-hydantoin. It is formed from alde-
hyde ammonia along with alanine (p. 371), if cyanide of potassium, containing

ALLOPHANIC ACID.

393

potassium isocyanate, be used in its preparation. It is very likely that then the
alanine (a-amidopropionic acid) first produced acts upon the cyanic acid (as in the
formation of hydantoic acid) {Berichte, 21, 516) : —

NH,.CH.CH3 .NH.CH.CH3

CO:NH+ I =CO<; I +H,0.

CO.OH ^NH.CO

a-Amido-Propionic Acid. Lactyl Urea.

It has one molecule of HjO, and crystallizes in large, rhombic prisms, which
effloresce on exposure. It melts at 140-145°, and sublimes with partial decom-
position. Boiled with baryta it absorbs water and forms a-Lacturic Acid,
C0/NH.CH(CH3).C03H, ^^^^ ^^,,^ ^^ ^^^^

^ "^ .NH— C(CH3)jj

Acetonyl Urea, CjHgN^Oj = CO^ | , a-Dimethyl-hydan-

^NH— CO
torn, the ure'ide of a-oxyisobutyric acid, (CH3)2.C(HO).C02H, is obtained like
the preceding compound, on heating acetone and potassium cyanide (containing
potassium isocyanate) with fuming hydrochloric acid. It is very soluble in water,
and crystallizes in large prisms, which melt at 175° and sublime in needles. When
heated to 160° with fuming hydrochloric acid, it breaks up into a-oxyisobutyric
acid, NHj and CO2. Boiling baryta water converts it into acetonyluric acid,
H2N.CO.NH.C(CH3)2.C02H, which fuses at 155-160°.

The ureldes of the dibasic acids and those of glyoxylic acid, CHO.COjH, will
receive attention under the uric acid derivatives. We will yet mention those of
carbonic acid : allophanic acid, biuret and carbonyl diurea.

Allophanic Acid, CO/^-|,jtt^/-.q tj, is not known in a free state. Its esters

are formed when chlorcarbonic esters act upon urea : —

co<nh: + ccio.o.CH, =co(NH^co,.c,H, + ^ci;

or by leading cyanic acid vapors into the anhydrous alcohols : 2C0:NH -\- C jHj.OH
= NH2.CO.NH.C02.C2H5. At first carbamic acid esters are produced (p. 383) ;
these combine with a second molecule of cyanic acid and yield allophanic esters
{Berichie, 22, 1572). The action of urea chloride upon alcohols (p. 376) proceeds
in a similar manner. The first products are carbamic esters. These unite with a
second molecule of the chloride and produce allophanic esters : CI.CO.NH2 +
H^NiCO.CjHj = H2N.CO.NH.CO2.C2H5 {Berichie, 2r, Ref. 293). The allo-
phanic esters are crystalline, dissolve with difficulty in water, and, when heated,
split up into alcohol, ammonia and cyanuric acid. The allophanates are obtained
from them by means of the alkalies or baryta water. They show an alkaline reac-
tion and are decomposed by carbonic acid. On attempting to free the acid by
means of mineral acids, it at once breaks up into CO, and urea.

^%/v4//tf/>5<7»2V-£j^^?',NH2.CO.NH.C02.C2H5, is obtained when hydrochloric
acid acts upon a solution of potassium isocyanate dissolved in alcohol. Shining
needles, melting at 190-191°. lY^e. propyl ester melts at 155°

AUophanamide, Cq/^^ (,q ^^ , Biuret, is formed on heating the allo-
phanic esters with ammonia to 100°, or urea to 150-160° : —

2C0\Nh' - ^"\NH.CO.NH, + ^"""a.
33

394 ORGANIC CHEMISTRY.

It is readily soluble in alcohol and water, and crystallizes with I molecule of
water, in the form of warts and needles; When anhydrous, biuret melts at 190°,
and decomposes further into NHj and cyanuric acid. The aqueous solution, con-
taining KOH, is colored a violet red by copper sulphate. Heated in a current of
HCl, biuret decomposes into NHj, CO2, cyanuric acid, urea and guanidine.

Carbonyl Diurea, CjHgN^O,, is formed on heating urea wfth COCl^ to
100° :—

.CO<NH. + COC, = CO<Ng-CO^^H\,^ ^ ,„,,

It is a crystalline powder, not readily dissolved by Nwater. Heat converts it inlo
ammonia and cyanuric acid.

Thio-urea, Sulphocarbamide, CS^j^tt'' . It is obtained by

heating ammonium thiocyanate to 170°, when a transposition,
analogous to that occurring in the formation of urea, takes place
(p. 387) :—

CSiN.NH^ yields Cs/^JI" ;
\iNxa2

and by the action of hydrogen sulphide (in presence of a little
ammonia), or ammonium thiocyanate upon cyanamide : —

CN.NH2 + SHj = CS<

Nnh^-

Preparation. — Heat dried ammonium thiocyanate to 180° for several hours.
The mass is then treated with an equal weight of hot water and the filtered solu-
tion allowed to crystallize {^Annalen, 179, 113).

Sulphocarbamide crystallizes in fine, silky needles, or in thick,
rhombic prisms, which dissolve easily in water and alcohol, but
with difficulty in ether ; they possess a bitter taste and have a neu-
tral reaction. They melt at 169° {Berichte, 18, 461) and decom-
pose at higher temperatures. When sulphocarbamide is heated with
water to 140° it again becomes ammonium thiocyanate. If boiled
with alkalies, hydrochloric acid or sulphuric acid, it decomposes
according to the equation : —

CSN2H4 -f- 2H2O = CO2 -f 2NH3 + H^S. .

Nitrous acid eliminates nitrogen. Silver, mercury, or lead oxide
and water will convert it, at ordinary temperatures, into cyanamide,
CN2H2; and on boiling into dicyandiamide (p. 289).

* The hypothetical isothiourea orimido-thiocarbamic acid, HN =: C(f ^tt ^, is

isomeric with thio urea. It is, however, only known in its derivatives (p. 396 and
phenyl-isothiourea). Both are probably tautomeric and change into each other,
while their alkyl derivatives are isomeric (p. 54, and Berichte, 18, 3103; 21,
1859)-

DERIVATIVES OF UREA WITH ACID RADICALS. 395

Thio-urea combines with i equivalent of acid to form salts. The nitrate,
CSNjH^.HNOj, occurs in large crystals. Auric chloride and platinic chloride
throw down red colored double chlorides from the concentrated solution. Silver
nitrate precipitates (CSN2H4)2.Ag20 + 4H2O, and mercuric nitrate, (CSNjH^)^
3HgO + 3H2O (see Berichte, 17, 297).

Compound Sulphocarbamides, in which hydrogen is replaced by alcohol radi-
cals, are formed : —

(1) On heating the mustard oils (p. 279) with amine bases : —

CSrN.C^H., + NH3 = CS^'^^-'^^Hs

Ethyl Sulphocarbamide \

CS:N.C,H, + NH^.CH, = Cs/nhIcH^'- . I

Ethyl-methyl Sulphocarbamide..^. ' , -j

(2) By heating the amide salts of the alkyl dithiocarbamic acids (piJES) : —

The sulphocarbamides regenerate amines and mustard oils by distillation with
P2O5, or when heated in HCl-gas: —

^S<NH(C2H^j = CSiN.C^H, + NH^.C^H,.

Ethyl Sulphocarbamide, CS<^jTrT' ^ ^, crystallizes in needles, melting
at 106°. jtA r ri

Diethyl Sulphocarbamide, CS<^j^j^'q^jj5^ consists of large crystals, not

very soluble in water. It melts at 77°. /jj'h CH
Methyl Ethyl Sulphocarbamide, CS^'j^pj'^ j|, is derived from ethyl

mustard oil and methylamine. It melts at 54°.

The sulphur in the alkylic sulphocarbamides may be replaced by oxygen if
these compounds are boiled with water and mercuric oxide. Those that contain
two alkyl groups yield the corresponding ureas : —

^S\NH.qH° + ^g° - '-"\NH.C2H5 + ^^^'

whereas the mono-derivatives pass into alkylic cyanamides (and melamines) after
parting with hydrogen sulphide (p. 289) : —

CS/^H-C^H^ ^ NjCNH.C^H. + SH^.

On digestine the dialkylic sulphocarbamides with mercuric oxide and amines,
oxygen is exchanged for the imid group and guanidine derivatives appear (p. 295) :—

.NH.C2H5 ' /NH.C^H^

CS/ + NH2.C2H, + HgO = C^N.qH^ -f HgS -f H,0.

\NH.CjH5 \NH.C2H5

Consult Berichte, 23, 283, upon the different propyl-sulphocarbamides.

396 ORGANIC CHEMISTRY.

AUyl Sulphocarbamide, CS(^tJ^ ' ^^ Thio-sinamine, is formed by the
union of allyl mustard oil with ammonia ; —

CSiN.CsH, + NH3 = Cs/^g'^'"^

It forms shining prisms, with bitter taste, and melts at 74°. It decomposes at
higher temperatures. It is readily soluble in water, alcohol and ether; combines
with one equivalent of acid, and forms salts with acid reaction. Water decom-
poses them. Allyl cyanamide and triallyl-melamine are produced on boiling with
mercuric oxide or lead hydroxide (p. 289). Foi' the constitution of the dialkyl
sulphocarbamides compare diphenyl-sulphocarbamides and Berichte, 23, 271.

Ethylene Sulphocarbamide, CS( -^-c, ^CjH^, is obtained from ethylene-
diamine and carbon disulphide {Berichte, 5, 242). It is crystalline, and melts at
194°. It does not combine with acids. CHj — S \

Ethylene-pseudo(iso) Sulphocarbamide, I ^C:NH or

CHj— S . CHj— NH/.

I ^C.NH2, is isomeric with the preceding. It is a derivative of pseudo-

CHj— N'^

sulphocarbamide (p. 391). It is obtained from HBr-ethyleneamine (p. 163) and
potassium thiocyanate. Bromethyl-sulphocarbamide, CHjBr.CHj.NH.CS.NHj,
is formed at first and splits off hydrobromic acid. Ethylene pseudo-sulphocarba-
mide is a base with strong basic properties. Its salts crystallize well. Alkalies
separate it from these in the form of an oil. This in time solidifies and then melts
at 85° [Berichte, 22, 1 141).

Propylene-pseudo-thio-urea, C3H5:CSN2Hj, from brompropylamine and
potassium thiocyanate, is perfectly similar. It also results from allyl thiourea by
action of hydrobromic acidi^Berichte, 22, 2984; 23, 964).

Acetyl sulphocarbamide and Thiohydantoin are considered as acid derivatives
of sulphocarbamide. The latter is undoubtedly a derivative of the isomeric iso-
thiocarbamide (p. 394).

Acetyl Sulphocarbamide, CS/NH.^^H,0, °' ^^ = c/^H.^^q, is
obtained from thio-urea by heating it with acetic anhydride. Its formation from
cyanamide (carbodiimide, p. 288) and thio-acetic acid argues for the .second
formula : —

CN.NH^ + C2H30.SH = NH:C/^^2jj q.

It crystallizes from hot water in prisms; these melt at 165°.

The so-called Thio- or Sulpho-hydantoln, CjH^NjSO, is not constituted
according to the formula I, corresponding to that of hydantoin (p. 391), but
according to 2 : —

.NH.CO .NH.CO

I. CS ( I and 2. HN:C.:; I .*

^NH.CHj ^S— CHj

Glycolyl Thio-urea. Glycolyl Isothio-urea.

* Real sulphohydantoins (of the formula i) have been prepared in the benzene
series (see phenyl sulphhydantoin and Berichte, 17, 425).

GUANIDINE DERIVATIVES. 397

The grouping {Annalen, 207, 121) in this instance is analogous to that shown
by the isothio-amides (p. 260) and the phenyl isothiourethanes (p. 396).

The c\Qst&,Jive-membered ring in thiohydantoin and in ethylene pseudo-thio-
urea consists of three C-atoms, one N-atom, and one S-atom. It is known as the
Thiazoline-nug. It is closely allied to thiazole derivatives (see these).

Sulphohydantoi'n is obtained when chloracetic acid and its anhydride act on
sulphocarbamide ; or (analogous to the formation of acetylsulphocarbamide) by
evaporating an aqueous solution of cyanamide and thioglycollic acid (p. 355), when
the sulphohydantoic acid (see below), produced at first, parts with a molecule of
water :—

,SH .NH.CO

CN.NHj + CH^^ = HN:C( | + H^O.

^COjH ^S — CHj

Sulphohydantoin crystallizes from hot water in long needles, and decomposes
near 200°. When boiled with baryta water it decomposes into thioglycollic acid
and dicyandiamide. Unlike the thio-ureas, it is not desulphurized when boiled
with lead oxide or mercuric oxide and water.

Boiling acids convert it into mustard-oil acetic acid, with elimination of NH3.

Isonitrosohydantoin (Berichte, ig, Ref 14) is produced by the action of
nitrous acid upon it. ytzvi

Sulphohydantoic Acid, CgHgN^SOj = HN:C(^g"^ ^-.q ^ is obtained

by heating sulphocarbamide with sodium chloracetic acid. It is a crystalline
compound, not very soluble in water. It resembles the amido-acids in having a
neutral reaction, but dissolves in alkalies and acids with production of salts. When
heated with acids it reverts to thiohydantoin.

GUANimNE DERIVATIVES.

Guanidine, like urea, is capable of yielding acid derivatives
(p. 296), but few of them, however, are known. Creatine and
creatinine, compounds of great significance physiologically, belong
in this class and are derived from glycocyamine.

Glycocyamine, CjHjNjOj, guanidoacetic acid, is obtained by the direct
union of glycocoU with cyanamide : —

/NH /^^^

CN.NH, + CH^C ro R = C=NH

Cyanamide. GlycocoU. Glycocyamine.

On mixing the aqueous solutions it separates after a time in granular crystals.
It is soluble in 120 parts cold water and rather readily in hot water; while it is
insoluble in alcohol and ether. It forms crystalline compounds with acids and
bases. When boiled with water and lead peroxide, or with dilute sulphuric acid,
it breaks down into guanidine, oxalic acid and carbon dioxide.

^-Guanidopropionic Acid, C^HgNgOj (alacreatine, CNjH^.CH^.CHj.
COjH), is homologous with the preceding, and is obtained in a similar manner
from cyanamide and ;9-amidopropionic acid. It decomposes at 205°. Isomeric
a-guanidopropionic acid melts at 180°

398 ORGANIC CHEMISTRY.

Glycocyamidine, C3H5N3O, glycolyl guanidine, bears the same relation to
glycocyamine as hydantoin to hydantoic acid (p. 391). Its hydrochloride is pro-
duced when glycocyamine hydrochloride is heated to l6o° : —

/NHj /NH— CO

C=NH = C=NH I + H2O.

\NH— CHj— COjH \NH— CHj

The free base crystallizes in deliquescent laminae, having an alkaline reaction.
PtClj precipitates its hydrochloride.

The methyl derivatives of glycocyamine and glycocyamidine are : —

.NH2 ,NH CO

NH=C/ NH=C( I

\N(CH3)-CH2-C0,H ^N(CH3)-CH,.

Creatine. Creatinine.

Creatine, C4H9N3O2, methyl glycocyamine, occurs in the animal
organism, especially in the juice of muscles. It may be artificially
prepared, like glycocyamine, by the union of sarcosine (methyl
glycocoU) with cyanamide : —

NH.CH3 .NHj

CN.NHj + I = NH:C(

CH2.CO2H \N(CH3)— CHj— COjH

To obtain creatine, exhaust finely divided flesh with cold water, boil the solution
to coagulate the albumen, precipitate the phosphoric acid in the filtrate with baryta
water and evaporate the liquid, then let it crystallize.

Creatine crystallizes with one molecule of water in glistening
prisms. Heated to 100°, they sustain a loss of water. It reacts
neutral, has a faintly bitter taste and dissolves rather readily in
boiling water; it dissolves with difficulty in alcohol, and yields
crystalline salts with one equivalent of acid.

When digested with acids, creatine loses water and becomes creatinine (see
above), and with baryta water it falls into urea and sarcosine : —

,NH, NH^ NH(CH3)

NH:C( +H„0 = CO/ + 1

^N(CH3)— CHj— CO2H ^NHj CHj.COjH.

Ammonia is liberated at the same time and methyl hydantotn (p. 392) is formed.
When its aqueous solution is heated with mercuric oxide, creatine becomes oxalic
acid and methyl guanidine. Ammonia and methylamine are disengaged when it
is ignited with soda lime.

Creatinine, C^HiNaO, methyl glycocyamidine, occurs con-
stantly in urine (about 0.25 per cent.), and is readily obtained
from creatine by evaporating its aqueous solution, especially when
acids are present. It crystallizes in rhombic prisms and is much
more soluble than creatine, in water and alcohol. It is a strong
base which can expel ammonia from ammonium salts and yields

DIBASIC ACIDS. 399

well crystallized salts with acids. Its compound with zinc chloride,
(C4H,NsO)2.ZnCl2, is particularly characteristic. Zinc chloride
precipitates it from creatinine solutions as a crystalline powder,
dissolving with difficulty in water.

Bases cause creatinine to absorb water and become creatine again. Boiled with
baryta water it decomposes into methyl hydantoin and ammonia : —

When boiled with mercuric oxide it breaks up like creatine into methyl-guanidine
and oxalic acid.

When creatinine is heated with alcoholic ethyl iodide, the ammonium iodide of
ethyl creatinine, C4H,(C2H5)N50.I, is produced. Silver oxide converts this
into the ammonium base, C4H,(C2H5)N30.0H.

DIBASIC ACIDS, CJi,,_,0^.

Oxalic Acid C^H^Oi = (CO^H),
Malonic " CjH.Oi = CHjCCO^H)^
Succinic Acids CiHeOt = CaH^CCO^H),
Pyrotartaric Acid CjHsO^ = CsHsCCO^H)^
Adipic " CeHioOi = CACCO^H)^, etc.

The acids of this series contain two carboxyl groups, hence are
dibasic. They are produced according to methods analogous to
those employed with the monobasic acids, by a repetition of the
formation of the carboxyl group.

The most important general methods are : —

(i) By oxidation of oxy-fatty acids, in which OH is linked to

CH2 :—

CH„.OH CO.OH

I +0^= 1 +H2O.

CO.OH CO.OH

Glycollic Acid. Oxalic Acid.

(2) By oxidation of the corresponding dihydric alcohols: —

CH..OH CO.OH

I +20^= I +2H2O.

CHj.OH CO.OH

Oxalic Acid.

(3) Conversion of monohalogen substituted fatty-acids into cyan-
derivatives, and boiling the latter with alkalies or acids (pp. 2 1 1

and 282): —

CH^.CN .CO^H

I +2H20 = CH2<; +NH3.

CO.OH ^CO^H

Cyanacetic Acid. Malonic Acid.

400 ORGANIC CHEMISTRY.

(4) Conversion of the halogen addition products of the alkylens,
CnH2„, into cyanides and the saponification of the latter : —

CH,.CN CH2.CO2H

+ 4H,0 = I +2NH3.

,.CN CH,.CO,H

CH,.C

Only the halogen products having their halogen atoms attached to
two different carbon atotns can be converted into dicyanides.

(5) A very general method for the synthesis of dibasic acids is
founded upon the transposition of aceto-acetic esters. Acid resi-
dues are introduced into the latter and the products decomposed
by concentrated alkali solutions (p. 341). Thus from aceto-
malonic ester we get malonic acid . —

CH3.CO.Ch/CO,.C,H3 y.^j,^ CH,<(CO.H.

and from aceto-succinic ester, succinic acid : —

/CHgiiCOg.CgHg
CHj.CO.CH^ yields |

^CO^.C.H, CH,.CO,H

(6) In a perfectly similar manner, higher dibasic acids can be
prepared from malonic esters, CH2(C02R)2. One hydrogen atom
of CHj is replaced by sodium and then the .alkyls introduced by
means of the alkyl iodides : —

CHNa^^°2-R yields CH(CH3)/^°2|, etc.
Sodium Malonic Ester. Methyl Malonic or Isosuccinic Ester,

In these monoalkylic esters the' second hydrogen atom can be
replaced by sodium and alkyls : —

CNa(CH,)(CO.R yields gg'^>C <^g^^^, etc.
Dimethyl Malonic Ester.

The free acids are obtained by saponifying the esters with
alkalies.

In performing these syntheses the malonic ester is mixed with the theoretical
amount of sodium dissolved in absolute alcohol (10 volumes), the alkyl iodide
added, and heat applied until the alkaline reaction disappears. After expelling
the excess of alcohol, the ester is precipitated with water (in preparing the dialkyl
derivatives 2 equivalents of sodium alcoholate and alkyl iodide are added. Annalen,
204, 1 29) . Tri- and poly-carboxylic acids may likewise be obtained by the introduc-
tion of acid esters (by means of chloracetic ester, etc. (p. 341 and Berichte, 15, 1 109).
The synthesis of the alkyl derivatives may also be effected by means of the alkyl
iodides and zinc [Berichte, ao, 203). AUyl iodide reacts similarly with zinc
{Berichte, 2,1, Ref. 181).

DIBASIC ACIDS. 40I

The dibasic acids .are also formed on oxidizing the fatty acids
CnHj^Oa, the acids of the oleic acid series, and the fats with nitric
acid. Potassium permanganate oxidizes some hydrocarbons, CnHj^,
to dibasic acids.

The acids of this series are solids, crystallizable, and generally
volatile without decomposition. They are mostly soluble in water
and have a strong acid reaction. The melting points of the normal
dicarboxylic acids exhibit the same regularity observed with the
fatty acids (p. 215), /. e., the members containing an even number
of carbon atoms melt higher than those with an odd number
{^Berichte, 10, 1286). The melting points of both series fall with
increasing carbon content {Berichte, 18, Ref. 59).

At higher temperatures those members which are capable of yield-
ing anhydrides part with water and pass into such compounds,
whereas, the others, having both carboxyl groups attached to one
carbon atom, decompose more or less readily into CO2 and mono-
basic fatty-acids (p. 211). Thus, from oxalic acid we get formic
acid, from raalonic acid, CH2(C02H)2, acetic acid, from isosuccinic
acid, CH3.CH(C02H)2, propionic acid, etc. Similarly, malonie
acid, and mono-alkyl malonie acids, R.CH(C02H)2, are decom-
posed, at the ordinary temperature, by concentrated nitric acid,
with the evolution of two molecules of carbon dioxide, while the
dialkyl malonie acids, R2C(C02H)2, and succinic, pyrotartaric and
the unsaturated acids, fumaric and maleic, etc., are unattacked by
cold nitric acid {Berichte, 18, Ref. 146; ig, Ref. 337).

Having two carboxyls, the dibasic acids can form neutral and
acid salts, likewise neutral and acid esters or ether-acids (similar to
sulphuric acid) : —

C TT /CO2.C2H5 „ „ /CO2.C2H5

Neutral Ester, Primary Ester,

The best method to use in making the neutral esters is to dissolve
the acid in alcohol, and while applying heat lead in a stream of
hydrogen chloride gas ; on adding water the ester is precipitated,
and may then be purified either by distillation or crystallization.

See Berichte, 14, 2630, for the ester formation of dibasic acids (p, 251),

With the dibasic acids the anhydride formation takes place within
one molecule and leads to the formation of inner anhydrides;
those resulting from the union of two molecules are not known (p.
34

402 ORGANIC CHEMISTRY.

351). The anhydrides are obtained by either heating the acids (see
above), or by the action of PCI5 (i molecule) : —

^^^KcoIh + PC's = '^^^*\co)° + ^^'3° + '^c'-

Succinic Acid. Succinic Anhydride.

In many cases the analogous action of chlorides of the fatty acids, e.g., acetyl
chloride, on the free acids or their silver salts, is better adapted to the preparation
of anhydrides {^Berichte, 13, 1844) : —

•^^^^XCO.OH + C.H3O.CI = C,H,/^g\o + C.H^O.OH + HCl.

It is a singular fact that anhydrides cannot be prepared from
oxalic acid, CjO^Hj, malonic acid, CH2(C02H)2, isosuccinic acid,
CH3.CH(C02H)2, etc., whereas succinic acid, normal pyrotartaric
acid, also maleic and phthalic acids are capable of such formations.
It seems, then, that anhydrides are only possible with dicarboxylic
acids (p. 352) in which there is a chain of four or five carbon atoms.*

The members obtained from succinic acid, by the entrance of
*alkylens, are more inclined to the formation of anhydrides accord-
ing to the number of methyl groups they may contain {Berichte,
23, loi and 620).

The anhydrides of this series are perfectly analogous in properties
and transpositions to those of the fatty acids ; they slowly dissolve
in water, more readily on heating, with regeneration of their acids.

When two molecules of phosphorus pentachloride are permitted
to act on the dicarboxylic acids chloranhydrides of the acids are
formed : —

C^H^XCO'.OH + 2PC'.^ = c^H*\co.ci + ^^^'3° + "HC'-

These behave in all respects like monovalent acid chlorides.

The divalent residues joined to the two OH's are termed the
radicals of the dicarboxylic acids, e.g., CjOj, oxalyl, CH2(CO)2,
malonyl, C2H4(CO)2, succinyl.

The amides are similar to those of the monobasic acids (p. 255). Both acia
amides or aviic acids, and the real diamides exist : —

P „ /CO.NH2 p „ /CO.NH2

Succinamic Acid, Succinamide.

* Malonic acid, succinic acid, and others, can be distilled without decompo-
sition under reduced pressure. Adipic acid, CjIJiqOj, is the first member of the
series that can be distilled at the ordinary pressure without sustaining decomposition
{Berichte, 22, 816).

DIBASIC ACIDS. 403

The imides are derived by substituting divalent acid radicals for two hydrogen
atoms in one molecule of ammonia [Annalen, 215, 172) : — ■

CgH^^PQ .NH, Succinimide.

The amide compounds may also be derived from the primary and neutral am-
monium salts by the withdrawal of water : —

Acid Ammonium Salt — HjO yields Amic Acid.

" « « — 2H2O " Imide.

Neutral " " — zH^O " Amide.

By withdrawing 4 molecules of HjO from the neutral salt the acid nitriles or
cyanides of the divalent alcoholic radicals result (p. 265) : —

P „ /CO.O.NH^ P „ /CO.NHj, „ „ /-CN

>-2J*4N^CO.O.NHi ^2"*\CO.NH2 ^2"*\CN-

Ammonium Salt. Amide. Nitrile,

The possible cases of isomerism correspond with those of the .
C„H2„ hydrocarbon groups ; the two COOH groups may be at-
tached to two different carbon atoms or to a single carbon atom.
Isomerides of the first two members of the series —

COjH .CO2H

I and CH.^(

COjH ^COjH

Oxalic Acid. Malonic Acid.

are not possible. For the third member two structural cases
exist : —

CHj.COnH yCC\ TT

I and CHj.CH/p^^".

CH,.CO,H \CO,il

Ethylene Dicarboxylic Acid, Ethidene Dicarboxylic Acid,
Succinic Acid. Isosuccinic Acid.

There are four possible isomerides with the formula CsHj^ CO^H'

etc. Many acids are named from malonic acid ; this accords with
their synthesis and is quite practicable (p. 400).

I*. Oxalic Acid, C2O4H2 {Acidum oxalicum), occurs in many-
plants, chiefly as potassium salt in the diiferent varieties of Oxalis
and Rumex. The calcium salt is often found crystallized in plant
cells ; it constitutes the chief ingredient of certain calculi. The
acid may be prepared artificially by oxidizing many carbon com-
pounds with nitric acid, or by fusing them with alkalies. It is

404 ORGANIC CHEMISTRY.

formed synthetically by rapidly heating sodium formate above
440° :—

CHO.ONa _ ^0-ONa

' run ONa — I ' 2'

CUU.uiMa cO.ONa

by oxidizing formic acid with nitric acid {Berichte, 17, 9) ; by
adding water to cyanogen : —

CN CO.O.NH4

I +4H,0= I ;

CN CO.O.NH^

and by conducting carbon dioxide over metallic sodium heated to
350-360° : —

2CO2 + Na^ = CjO^Na^.

Formerly, the acid was obtained from the different oxalis species or by oxi-
dizing sugar with nitric acid. At present it is prepared on an immense scale by
fusing sawdust (cellulose) with a mixture of KOH and NaOH (eqjial parts) in
iron pans and inaintaining a temperature of 200-220°. The brown fusion is
extracted with water and boiled with millc of lime. The separated calcium salt
is decomposed with sulphuric acid and the filtrate evaporated to crystallization.

The ease with which sodium oxalate is produced from sodium formate (above),
and the latter from CO and NaOH (p. 217) would make it appear possible to
obtain the acid on a commercial scale by these reactions {Berichte, 15, 150.8).

Oxalic acid with the formula, CjHjOi -(- 2H2O = C2(OH)6, crys-
tallizes in fine, transparent, monoclinic prisms, which effloresce at
20° in dry air and fall to a white powder. It is soluble in 9 parts
of water of medium temperature, and quite easily in alcohol. The
hydrated acid melts at 101° if rapidly heated, and the anhydrous
at 189° {Berichte, 21, .1901). When carefully heated to 150° the
anhydrous acid sublimes undecomposed ; rapidly heated it decom-
poses into formic acid and carbon dioxide : —

C^H^Oi = CH,0, + CO2.

Oxalic acid decomposes into carbonate and hydrogen by fusion
with alkalies or soda-lime (p. 218): —

CpjCj + 2KOH = 2C0s K2 + Hj.

Heated with concentrated sulphuric acid it yields carbon monox-
ide, dioxide and water : — ^

qHA = COj -h CO + H^O.
Nascent hydrogen (Zn and H^SOi) converts it into glycollic acid.

The oxalates, excepting those with the alkali metals, are almost insoluble in
water.

The neutral potassium salt, C^O^K, -|- HjO, is very soluble in water, and parts
with its water of crystallization at 180°. The acid salt, C2O4HK, dissolves with

ESTERS OF OXALIC ACID. 405

more difficulty, and occurs in the juices of plants (of Oxalis and Rumex). Potas-
sium quadroxalate, C^O^KH, C^O^H^ + zHjO, forms triclinic crystals, soluble
in 20 parts of water at 20° Commercial salt of sorrel consists generally of a
mixture of the acid and the super-salt.

Neutral Ammonium Oxalate C20^(NH^)2 + HjO, consists of shining,\
rhombic prisms, and is easily soluble in water. When heated it becomes oxamide,
which further decomposes into CgN^, COj, CO and NH3. Acid ammonium
oxalate, Cfi^[^Yi.^, yields oxamic acid on heating. The calcium oxalate,
CjO^Ca + H^O, is formed in a crystalline state in plant cells; it is precipitated
as a white crystalline powder (quadratic octahedra) on the addition of an oxalate
to a warm solution of a calcium salt. (A salt with sH^O separates from very
dilute and cold solutions.) Calcium oxalate is insoluble in water and acetic acid,
but is dissolved by the mineral acids. It parts with its water of crystallization at
200°. The silver salt, CjO^Agj, explodes when quickly heated.

ESTERS OF OXALIC ACID.

Oxalic Methyl Ester, C202(O.CH3)2,is obtained by distilling oxalic acid (i
part) or potassium oxalate (2 parts) with methyl alcohol (l part) and sulphuric
acid (i part) ; or by boiling anhydrous oxalic acid with methyl alcohol. It forms
large, rhombic plates, which are easily soluble in water and alcohol ; possesses an
aromatic odor, melts at 5l°^and distils at 163°. Water, especially when boiling,
decomposes it into oxalic acid and methyl alcohol.

CO.O.CH3

The acid ester (methyl oxalic acid), | , is very unstable, and is found

CO.OH i

in the mother-liquor from the neutral ester.

Oxalic Ethyl Ester, C202(O.C2lf5)2, is an aromatic-smelling liquid, of sp. ,
gr. 1.0793 ^t ^o*" ajid boils at 186°. It diss'olves with difficulty in water, and is
gradually decomposed by it into oxalic acid and ethyl alcohol. It is produced.by
distilling equal parts of salt of sorrel, alcohol and sulphuric acid. The following
method yields it more readily. Anhydrous oxalic acid (3 parts) is dissolved on the
water bath, in absolute alcohol (2 parts), and the solution then introduced into a
tubulated retort and heated to 100°. Gradually raising the temperature to 130°,
the vapor of z parts absolute alcohol is conducted into the liquid; water and alco-
hol distil off. The oxalic ester is separated from the residue by fractional distil-
lation {Berichte, 18, Ref. 221).

It forms oxamide and alcohol when shaken with aqueous ammonia ; dry ammo-

/O C IT
nia converts it into oxamic ester. Potassium ethyl oxalate, CjOj^'qVt^ '

mixed with CjOjK^, is precipitated by adding alcoholic potash to a solution, of
oxalic ester. The same salt is formed when monochloracetic ester is heated with
KNOj. It is a crystalline powder, which decomposes above 140°. Vrse ethyl
oxalic acid is obtained by heating anhydrous oxalic acid with absolute alcohol,
and distils undecomposed at 117° under 15 mm. pressure. Distilled under ordi-
nary atmospheric pressure it decomposes into COj, formic ester and oxalic ester.
See Berichte, 19, 1442; 22, 1807, for homologous alkyloxalic acids.

/CI
POCI3 converts potassium ethyl oxalate into chloroxalic ester, C^Oj^" q /- ji

A better method is to heat oxalic ester with PCI 5 until no more ethyl chloride is
disengaged : —

CO.Cl
+ PC1, = | -f POCI3 + C^H.Cl. ;

4o6 ORGANIC CHEMISTRY.

The first product is di-ethyl dicWorglycollic ester, which, upon distillation, sepa-
rates into CjHjCl and chloroxalic ester : —

CO.Cl

I + C.H^Cl.

CO.O.C2H5 CO.O.C2H5

This course is very convenient for the preparation of the ester of chloroxalic acid
{Berichte, 19, 2159). The action of PClj- upon the homologues of oxalic ester is
similar (Berichte, ig, 1443, Ref. 806).

When separated from the POCI3 by fractional distillation, ethyl oxalyl chloride
is a pungent-smelling liquid, boihng at 131.5°. It fumes strongly in the air and
rapidly decomposes into oxalic acid. It sinks in water and gradually passes into
oxalic acid, hydrochloric acid and alcohol. It reacts very energetically with alco-
hols and forms neutral esters. By further heating with PCI5, it is slowly changed
to trichloracetic ester.

The Isoamyl Ester, C202(O.C5H,j)2, is obtained by heating amyl alcohol

with oxalic acid. It is a thick oil which boils at 262°, and smells like bedbugs.

/CI
Phosphorus pentachloride converts it into amyl oxalyl chloride, C^O,^ n r w

an oil which partly decomposes on the application of heat [^Berichte, 14, 175°);
diamyl dichlorglycoUic ester [^Berichte, 19, 1443) is an intermediate product.

The AUyl Ester, €202(0.03115)2, obtained by the action of allyl iodide on
silver oxalate, boils at 206-207°, and has a specific gravity of 1.055.

AMIDES OT OXALIC ACID.

Oxamide, C202(NH2)2, separates as a white, crystalline powder,
when neutral oxalic ester is shaken with aqueous ammonia. It is
insoluble in water and alcohol. It is also formed when water and
a trace of aldehyde act on cyanogen, CjNj, or by the direct union
of hydrocyanic acid and hydrogen peroxide (2CNH -)- HjOj = Cj
O2N2H4). Oxamide is partially sublimed when heated, the greater
part, however, being decomposed. When heated to 200° with
water, it is converted into ammonium oxalate.

Hydrorubianic Acid (p. 265) may be considered as Dithio-oxamide, C2S2
(NH2)2, or isothio-oxamide, C2(SH)2(NH2)2.

The substituted oxamides containing alcohol radicals are pro-
duced by the action of the primary amines upon the oxalyl esters,
e.g.:—

C „ /NH.CH3 „ „ /NH.C2H5

Dimethyl Oxamide, Diethyl Oxamide.

These compounds are more soluble in hot water and alcohol than
oxamide, and distil without decomposition. The first melts at 210°.
The alkalies break them up into oxalic acid and amines.

OXAMIC ACID. 407

When two molecules of PCI5 act upon dimethyl or diethyl oxamide the oxygen
atoms are replaced by chlorine. The resulting amid-chlorides (p. 258) —

CCl2.Ntl.CH3 CCl2.NH.CjH5

I and I ,

CCI2.NH.CH3 CCI2.NH.C2H5

readily part with three molecules of HCl and yield chlorinated bases : chloroxal-
meihylin, C^HjClN^, and chloroxalethylin, C5HgClN2. Both are very alkaline
liquids, soluble in water; the first boils at 205°, the second at 217-218°. On heat-
ing them with hydriodic acid and amorphous phosphorus we get bases that do not
contain chlorine ; Oxalmethylin, C4H8N2,andOxalethylin, CgHj^Nj; the first
is identical with methyl glyoxaline, the second with ethyl glyoxalethylin (p. 325).

Oxamic Acid, Q.^^'f^^^' , is obtained from its ammonium salt, which is pro-
duced by heating acid ammonium oxalate, or by boiling oxamide with ammonia,
and then liberating the acid with hydrochloric acid [Berichte, 19, 3229). It is
most easily obtained by boiling oxamethane with ammonia (.Smc/i/if, 22, 1569).
It is a crystalline powder, that dissolves with difficulty in cold water, and melts at
1 73°. It is monobasic and forms crystalline salts. It passes into acid ammonium
oxalate when heated with water.

Its esters result from the action of alcoholic, or dry ammonia upon the esters of
oxalic acid : —

Ethyl Oxamic Ester (Oxamethane), C^OjCf ^ p'tt consists of shining, fatty-

feeling leaflets. It melts at 114-115° and boils at 200°. PCI5 converts it into the
amid-chloride, CCl2(NH2).CO.O.C2H5 (see above), a crystalline compound, which
reverts to oxamethane, when exposed to moist air. HCl separates when heat is
applied and the product is cyancarbonic ester, CN.CO.O.CjHj. Isomeric bodies,
alkylic oxamic acids, are obtained by heating salts of the primary amines of

• XTTT /-. TT

oxalic acid. Ethyloxamic acid, C202^qtt' ^ 5, crystallizes in six-sided plates
and melts at 120°. /NfC H "l

Ethyl Dietho- oxamic Ester, Q.j^^Cr}'c\f (Diethyloxamethane),boilsat254°

and is produced by the action of diethylamine upon oxalic esters. It regenerates
diethylamine on distilling with potash. A method for separating the amines (p.
158) is based on this behavior.
CO,
Oxalimide, \ ^ NH, is obtained from oxamic acid by the aid of PCI5 or PCI3O.

co/

It dissolves with difficulty in cold water, and crystallizes in shining needles from
hot water. Boiling water decomposes it into oxalic acid and oxamide. Aqueous
ammonia converts it into oxamide [Be}-ichte, ig, 3229).
Cyanogen is the nitrile of oxalic acid (p. 263).

The oximido-ether is produced when HCl acts upon cyanogen in
alcoholic solution : —

CN C(NH).O.C2H5

I -f 2C2H5.OH = I
CN C(NH).O.C2H5

408 ORGANIC CHEMISTRY.

This is analogous to the formation of the itnido-ethers (p. 292)
from nitriles.

Alcoholic ammonia converts the product into oxamidine,
C(NH).NH2

I (Berichte, 16, 1655).

C(NH).NH2

C(N.OH).NH,
Oxaldiamid-oxime, | , the dioxime of oxamide, is formed when

C(N.OH).NHj
ammonia acts upon oximido-ether, or hydroxylaniine (2 molecules) upon cyano-
gen, CN.CN, upon cyan-aniline, or hydrorubianic acid (p. 265). It crystallizes,
from alcohol, in white needles, melting at 196°. It exhibits all the properties of
the amidines, and dissolves in acids and alkalies ( Berichte, 22, 2942 and 2946).

(2) Malonic Acid, C3H4O4 = CHjCCOOH)^, occurs in the
deposit found in the vacuum pans employed in the beet sugar
manufacture. It is obtained by the oxidation of malic acid (and
hydracrylic acid) with chromic acid : —

COjH
CH^.COjH I

I +Oj = CH, +C0, -fH.O;

CH(0H).C02H \

CO,H

by the decomposition of malonyl urea (barbituric acid, see this)
with alkalies, and by the oxidation of propylene and allylene with
potassium permanganate. It may be prepared, too, by boiling
cyanacfetic acid (p. 262) with alkalies or acids : —

CH.<^0,H + ^H,0 = CH./CO.H ^ ^^^

Preparation. — loo grams of chloracetic acid, dissolved in 200 grams of water,
are neutralized with sodium carbonate (i 10 grams), and to this 75 grams of pure,
pulverized potassium cyanide are added, and the whole carefully heated, after
solution, upon a water-bath. The cyanide produced is saponified either by con-
centrated hydrochloric acid or potassium hydroxide (Berichte, 13, 1358, and
Annalen, 204, 125). To obtain the malonic ester directly, evaporate the cyanide
solution, cover the residue with absolute alcohol and lead HCl gas into it (Anna-
len, 218, 131).

Malonic acid crystallizes in large tables or laminae. It is easily
soluble in water, alcohol and ether, and melts at 132°- At higher
temperatures it decomposes into acetic acid and carbon dioxide.
The ethyl ester is similarly broken up into COj and acetic ester
when it is heated with water to 150° Bromine in aqueous solution
converts it into tribromacetic acid and COj. Its barium salt,

MALONIC ACID. 409

(C3H204)Ba "1- 2HjO, forms silky, shining needles. The calcium
salt, (CgHjOjCa) ■\- 2H2O, dissolves with difificulty in cold water,
hence is precipitated by calcium chloride from neutral solutions.
Silver nitrate precipitates the silver salt, CgHjAgjOi, as a white,
crystalline compound.

The malonic esters are obtained by dissolving the acid in alcohol, and conduct-
ing HCl-gas into the solution (see above).

The methylester, CH2(C02.CH3)2, boils at 175-180°. The ethyl ester \>oKii at
195°: its specific gravity at 18° is 1.068. This compound is useful in performing
various syntheses (see above). By the action of sodium ethylate upon it the
Na-compounds, CHNa(C02.C2H,)2 and CNa2(C02.C2H5)2 [Berichte, 17,
2783), result. Upon heating sodium malonic ester to 145° a condensation of 3
molecules occurs, with a splitting off of 3 molecules of alcohol, and there
remains the ester of trisod-phloroglucin tricarboxylic acid (a derivative of ben-
zene) [Berichte, 18, 3458) : —

3CHNa(C02.C2H5)2 = Ce03Na3(C02.C2H,)3 -f 3C2H,.OH.

The amide of malonic acid (CH2.(CO.NH2)2), formed from malonic ester and
ammonia, consists of crystals, and melts at 170° (Berichte, 17, 133).

Malononitrile, CH2(' /-vr, methylene cyanide, is obtained by distilling cyanace-

tamide, CN.CHj.CO.NHj, with P2O5. A crystalline mass, melting at 30° and
boiling at 218° C. Silver nitrate precipitates CAg2(CN)2 from the aqueous solu-
tion [Berichte ig, Ref. 485).

As in the aceto-acetic esters, so in the malonic esters, the hydrogen of the methy-
lene group (CHg) can be replaced by alkali metals (p. 400). Malonic ester
unites with formaldehyde to produce propantetracarboxylic ester [Berichte, ig,
1054). Consult Berichte, 20, Refs. 504, 552, upon the action of sodmalonic
esters upon unsaturated acids.

When iodine acts upon sodmalonic ester the product is an ester of ethane-tetra-
carboxylic acid. The disodium compound, under like treatment, would yield
ethylene-tetracarboxylic ester, C2(C02R)4-

When nitrous acid is conducted into the solution of the sodium compound of
the ethyl ester, isonitrosomalonic ester, C(N.0H)(C02. €2115)2, is formed.
This is a yellow oil which decomposes when heated. Its specific gravity at 15°
is 1. 149. Saponification with alkalies liberates isonitrosomalonic acid,
C(N.OH)(C02H)2. This is also formed by the action of hydroxylamiM>-
[Berichte, 16, 608, 1621) upon violuric acid (see this) and mesoxalic aod,
CO(C02H)2. It is easily soluble in water, crystallizes in shining needles, and
melts near 126°, decomposing at the same time into hydrocyanic acid, carbon
dioxide and water. Nitroxnalonic Ester, CH(N02)(C02.C2H5), forms when
malonic ester dissolves in concentrated nitric acid." It dissolves in ammonia and'
forms an ammonium salt [Berichte, 23, Ref. 62). Amidomalonic Acid,
CH(NH2).(C02H)2, is obtained from it by reduction with sodium amalgam. This
new acid is readily dissolved by water, and when warmed passes into glycocoU,
CH2(NH2').C02H and CO2. Tte amide of amidomalonic acid is obtained from
chlormalonic ester [Berichte, 15, 607).

Chlormalonic Ester, CHC1(C02. 02115)2 is obtained by conducting chlorine
into warm malonic ethylate. It boils at 222°. When saponified with excess of
caustic alkalies it yields oxymalonic acid (tartronic acid), CH.OH.(C02H)2. The
addition of one molecule of sodium ethylate to its solution produces at first sodium
chlormalonic ester, CNaCl(C02R)2- The alkylogens convert this into chlorinated

41 0 ORGANIC CHEMISTRY.

alkyl malonic esters {Berichte, 13, 2159). The latter yield higher oxydicarboxylic
acids, R.C(OH){C02H)2 {Annalen, 209, 232), when saponified with excess of
caustic alkalies.

Two molecules of sodium alcoholate convert it into the sodium sail of chlor-
malonic acid, which crystallizes in shining prisms that melt at 133°, and at 180°
decompose into COj and monochloracetic acid {^Berichte, 15, 605).

Monobrom-malonic Acid, CHBr(C02H)2, is produced in slight quantity
when malonic acid is treated with bromine. It consists of deliquescent needles.
Silver oxide converts it into oxymalonic acid (tartronic acid).

Dibrom-malonic Acid, CBr2(CO.OH)2, is formed when bromine (dissolved
in chloroform) is allowed to act upon malonic acid. Deliquescent needles, which
melt at 126° and then decompose. Heated with baryta water it changes to dioxy-
malonic acid (mesoxalic acid).

Cyanmalonic Ester, CH(CN)(C02R)2, results from the action of cyanogen
chloride upon sodium malonic ester (^Berichte, 20, Ref. 563), or acetyl chloride
upon sodium cyanacetic ester. It is a pungent-smelling liquid which boils with
decomposition in a vacuum. It has a very acid reaction, and decomposes the alka-
line carbonates, forming salts, like CNa(CN){C02R)2 {Berichte, 22, Ref. 567).

3. Succinic Acids, C4H5O4 := Q^/ rn^R-

\C02H-

CH2.CO2H* .CO2H

1 CH3.CH(

CH2.CO2H ^COjH

Ordinary Succinic Acid. Isosuccinic Acid.

I. Succinic Acid, or ethylene dicarboxylic acid, occurs in
aniber, in some varieties of lignite, in resins, turpentine oils and in
animal fluids. It is formed in the oxidation of fats with nitric acid,
in the fermentation of calcium malate or ammonium tartrate and
in the alcoholic fermentation of sugar.

It is synthetically prepared : —

(i) By boiling ethylene cyanide (from ethylene bromide) (p. 303)
with alkalies or acids : —

CH2.CN CHo.COjH

I +4H20=| +2NH3;

CH2.CN CH2.CO2H

(2) By converting /3-iodpropionic acid (p. 224) into cyanide
and decomposing the latter with alkalies or acids : —

^'^^x^CHj.COjH "t" ^"2^ — ^"2\CH2.C02H ^ ^^"3.

* Considered stereochemically, succinic acid must have the axial-symmetric
HO2C.CH2
configuration, I . The plane-symmetric form is unstable, and is

CH2.CO2H

CH2.CO.
ojAy fixed in succinic anhydride, | ^O.

CH,.CO/

SUCCINIC ACID. 411

(3) By the action of nascent hydrogen upon fumaric and malelc
acids: —

r H /COjH . „ „ „ /CO.H

(4) By reducing malic acid (oxysuccinic acid) and tartaric acid
(dioxysuccinic acid) with hydriodic acid (p. 41) : —

CH2.CO2H CHj.COjH

I +2HI= I +H,0 +I„

CH(OH).COjH CH^.CO^H

Malic Acid. Succinic Acid.

CH(OH).CQ2H CHj.COjH

I +4HI= I +2H,0 + 2l,.

CH(0H).C02H CHj.COjH

Tartaric Acid.

Malic acid undergoes a like reduction in the fermentation of its
calcium salt.

(5) By the decomposition of aceto-succinic esters (p. 400), and
from ethene-tricarboxylic acid by the elimination of carbon dioxide.

Preparation. — Distil amber from "an iron retort; evaporate the distillate and
purify the residual, brown crystalline mass, by crystallization from dilute nitric
acid. The acid is easily prepared by letting calcium malate ferment. Water
and rancid cheese are added to crude calcium malate and the mixture let stand
at a temperature of 30-40° for several days. Subsequently the succinate of cal-
cium, obtained in this manner, is decomposed with sulphuric acid, the gypsum
filtered off and the filtrate evaporated to crystallization. Consult Berichte, 14, 214,
upon the production of succinic acid by the fermentation of ammonium tartrate.

Succinic acid crystallizes in monoclinic prisms or plates, and has
a faintly acid, disagreeable taste. It melts at 180° (185°) and dis-
tils at 235°, at the same time decomposing partly into water and
succinic anhydride. At the ordinary temperature it dissolves in 20
parts of water. It dissolves with more difficulty in alcohol. Ether
will extract nearly all of the acid from its aqueous solution.

Uranium salts decompose aqueous succinic acid in sunlight into
propionic acid and COj. The galvanic current acts as indicated
by the equation (p. 87) : —

qH.cco^H)^ = qn, + 2CO, + H3.

It (also the alkyl succinic acids) forms fluorescein dyes when heated with resor-
cinol and sulphuric acid.

The salts with the alkali metals are readily soluble in water. The potassium
sail, C4H^04K2 + 3H2O, forms deliquescent needles. The calcium salt,
C^H^O^Ca, separates with 3 molecules of HjO from a cold solution, but when
it is deposited from a hot liquid it contains only iH^O. It dissolves with diffi-
culty in water. When ammonium succinate is added to a solution containing a
ferric salt, all the iron is precipitated as reddish-brown basic ferric succinate.

Ethyl Succinic Ester, Cfi^QO^.C.^^^, is obtained in the action of hydro-

412 ORGANIC CHEMISTRY.

chloric acid upon an alcoholic solution of succinic acid. It is a thick oil, insoluble
in water and boils at 216°.

Its specific gravity at 0° is 1.072. Sodium converts it into ethyl succino-succi-
nate.

Methyl Succinic Ester, CjHi(C02.CH3)2, has been obtained from silver sue
cinate and methyl iodide, as well as from succinyl chloride and sodium methylate.
It melts at 19°, and boils at 80°, under a pressure of 10 mm.

Ethylene Succinic Ester, C^Ji^/^Q^yC^H^, is produced by heating suc-
cinic acid and ethylene glycol to 200°. It fuses at 90°, and decomposes upon dis-
tillation.

Succinic Anhydride (succinyl oxide), C^H^J^qq^O, is produced in the dis-
tillation of succinic acid, or more readily by heating it with i molecule of PCI5 ;
further, by heating succinic acid with acetyl chloride (p. 402). It crystallizes in
needles or prisms from alcohol or ether, melts at 120° and distils at 250°. When
boiled with water, it reverts to succinic acid.

Two molecules of PCI 5 convert succinic acid into —

Succinyl Chloride, C^nycaCl' " '^2^4\CO '/° i^^''''^^^' ^^' 3'84)-
This is an oil, solidifying at 0° and boiling at 190°. It forms succinic dimethyl
ester with 2 molecules of sodium methylate. By acting with sodium amalgam
upon an ethereal solution of succinyl chloride and glacial acetic acid, we get

butyrolactone, C^}i^^7^7^^\o (p. 362), which was formerly considered succinic

dialdehyde, CjHi(CH0)2.

Zinc ethide converts succinyl chloride into C,,ll^<iS^ ^ ^'^yo, y-diethyl-

butyrolactone, which boils at 230° ; it forms salts of the corresponding acid with
alkalies.

' Succinamide, CjHj/pQ'itf;'', is produced by shaking succinic ester with

aqueous ammonia. It is a white powder. It is insoluble in water and alcohol,
and crystallizes, from hot water, in needles. At 200° it decomposes into ammonia
and succinimide.

Ethylene cyanide, CjH4(CN)2, (p. 303), is the nitrile of succinic acid.

Succinimide, CaH^^'^Q yNH. Gentle ignition of the anhy-
dride in a current of dry ammonia or the distillation of ammonium
succinate produces this compound. It crystallizes with i molecule
of HjO in rhombic plates, and dissolves readily in water and
alcohol. It crystallizes from acetone in rhombic octahedra without
any water. When anhydrous it melts at 126° and boils at 288°.

Succinimide combines with metallic oxides like those of silver and lead, exchang-
ing its imide hydrogen for metals, for instance, CjH^^' j,„ ^NAg. The same com-
pounds are obtained by the double decomposition of the potassium derivative with
salts of the heavy metals {Annalen, 215, 200). The potassium compound, CjHj
(C0)2NK and C^U^iCCTj^Y:. -f ^H^O, is formed by adding alcoholic potash to
an alcoholic solution of succinimide. Ether precipitates it, either as a powder, or
crystalline mass. The silver salt, C,H4(CO)2NAg and C2H4(CO)2NAg -f
yiH^O, crystallizes in silky needles.

PYRROLIDINE.

413

These compounds show that succinimide, like other imides, possesses
an acid character.

It is not only the carboxyl group that determines the acid char-
acter of the carbon compounds ; the imide group, NH, also seems
capable of exchanging hydrogen for metals (forming salts), if it
be attached to one or two carbonyl groups, CO (as in CO = NH,

cyanic acid, and in pQ ^ NH). This is particularly manifest in the

urea derivatives of the dicarboxylic acids (see these).

Methyl Succinimide, C2H^(^„j-.^N.CH3, is obtained by distilling methyl-
amine succinate. It crystallizes in leaflets, melts at 66.5° and boils at 234°-

Ethyl Succinimide, C2H^(fpQ^N.C2H5, crystallizes in broad needles, which
dissolve easily in water, alcohol and ether. It melts at 26° and boils at 234°.

On distilling succinimide with zinc dust, oxygen is withdrawn
and pyrrol, C^HsN (see this), is formed : —

CHj.CO. CH = CH.

1 )NH yields I ^NH.

CH^.CO^ CH = CH-^

Succinimide. Pyrrol.

Ethyl Pyrrol, CiH4N(C2H5), is obtained in a similar manner from
ethyl succinimide.

Pyrrolidine, C4H9N {Berichte, 20, 2215), is formed in the action
of sodium upon succinimide dissolved in absolute alcohol.

Succinamic Acid, ^■i}^iCcT\(\iL' '^ produced by heating succinimide with
baryta water : —

C,H /COXj,H ^ H,0 = C,H /CaNH,

It is crystalline, and water decomposes it with ease into succinic acid and
ammonia.

See Annalen, 254, 155, upon the Chlorsuccinic Acids.

Mono- and Dibrom-succinic Acids are formed when succinic acid, bromine
and water are heated to 150-180° in sealed tubes. The first is the chief product
when an excess of water is used. The bromine is more readily introduced into
succinic esters, or succinyl chloride, or the anhydride (p. 221). It is not even
necessary to use the last two compounds as such ; it will suffice to warm the sue-
cinic acid with amorphous phosphorus and water {Berichte, ai, Ref. 5).

/PO IT

Monobrom-succinic Acid, CjHjBri' pj-,*TT, is obtained by the union of

fiimaric or male!c acid with HBr(C^H404 -)- HBr = C^HjErO^) [Annalen, 254,
161). It crystallizes in warty masses, consisting of minute needles, and is readily

414 ORGANIC CHEMISTRY.

soluble in water. It melts at l6o°, and decomposes into HBr and fumaric acid.
It suffers similar decomposition when heated with water. On boiling with moist
silver oxide it yields oxysuccinic acid, C2H3(OH)(COjH)j (Malic Acid). Its
ethyl ester, CjH3Br(COj.CjH5)2, boils at 150-160°, under 50 mm. pressure.
With KCN, or when distilled at the ordinary temperature, it forms fumaric ester

,CO
(Berichte, 22, Ref. 813). Its anhydride, CjHjBr^ >0, is produced by heat-

-^CO
ing the acid with acetyl chloride. It melts at 30°. When distilled it decomposes
into hydrobromic acid and maleic anhydride.

Dibrom-succinic Acid, Z^fi'c^O.^^, results by the direct union of
fumaric acid with bromine. It may be obtained by heating succinic acid (12
parts) with bromine (33 parts) and water (12 parts) to 150-180°, until all the
bromine has disappeared. It is more easily prepared by heating fumaric acid with
bromine and water to 100° C. (^Berichte, 18, 676). It consists of prisms which
are not very soluble in cold water. When heated to 200-235° it breaks up into
HBr and brommaleic acid. Boiling water decomposes its salts ; the silver salt
yields dioxysuccinic acid (inactive tartaric acid), the sodium-salt monobrom-malic
acid, C2H2Br(OH)(C02H)j, and the barium salt, inactive tartaric acid and mono-
brom-maleic acid, C2HBr(COjH)2. When dibromsuccinic acid is heated with a solu-
tion of potassium iodide it becomes fumaric acid; boiling water decomposes it into
HBr and brommaleic acid. The methyl ester, C2H2Br2(C02.CH3lj, melts at
62° ; the ethyl ester at 68°, and when distilled it suffers decomposition. It forms
fumaric ester when digested with reduced silver.

Isodibrom -succinic Acid, C2H2Br2(C02H)2, is isomeric with the preceding.
It is obtained in slight quantity by adding bromine to succinic acid, but is better
prepared by the addition of Br^ to maleic acid (see this), or by digesting the anhy-
dride of the latter with water. It is crystalline and very soluble in water. It melts
at 160° and decomposes at 180°, or by boiling with water, into HBr and so-called
brona-fumaric acid (p. 425). Silver oxide and water convert it into brom-fumaric
and racemic acids (Berichte, 21, 267). Sodium amalgam changes it to succinic
acid. When warmed with a solution of potassium iodide it passes into fumaric
acid.

The esters of this acid are prepared by conducting HCl-gas into the alcoholic
solution of the acid. They are liquids, and readily decompose when heated. The
anhydride, C2H2Br2(CO)20, results on heating maleic anhydride, C2H2(CO)20, to
100° with bromine (dissolved in chloroform). It crystallizes in tables, melts at
42°, and at 100° decomposes into HBr and brom-maleic anhydride. It readily
unites with water to yield isodibrom-succinic acid.

Both dibrom-acids are converted by alcoholic potash into acetylene dicarboxylic
acid, C2(C02H)2 (p. 431)-

It was generally assumed that the two dibrom-acids were derived
from ordinary succinic acid and corresponded to the formulas ; —

CHBr.COjH

CBrj-COjH

CHBr.C02H

and 1 .

CHj.COjH

Dibromsuccinic

Isodibromsuccinic

Acid.

Acid.

Their reactions, however, indicate that both have the iirst struc-
tural formula {Berichte, 21, 264, 788). They, therefore, exhibit
the phenomenon of alloisomerism (p. 50), analogous to that of all

DIAMIDO-SUCCINIC ACID. 415

CHX.COjH
the other symmetrical disubstituted succinic acids, |
(p. 419)- CHX.CO.H

Tribrom-succinic .Acid, CjHBr3(C02H)2, is produced when bromine (and
water) acts upon brom-maleic acid and isobrom-maleic acid ; it consists of acicular
crystals, which melt at 136-137°. The aqueous solution decomposes at 60° into
COj, HBr, and dibromacrylic acid, CjHjBrjOj, which melts at 85°.

Sulpho-succinic Acid, CjHj -j k-^ f, •'2, is obtained by dissolving succinic

acid in fuming sulphuric acid, or by the union of fumaric or maleic acid with pri-
mary alkali sulphites. It is tribasic.

C(N.0H).C02H
Isonitroso-succinic Acid, I , oximido-succinic acid. Its ethyl

CHj.COjH
ester is forme.d by the action of hydroxylamine hydrochloride upon oxalo-acetic
ester. It is a colorless oil. Sodium amalgam reduces it to aspartic acid {Berichte,
21, Ref. 351). The mono-ethyl ester is obtained from the dinitroso derivative of
succino -succinic ester. It yields ethylic-asparto-ether acid (Berichte, 22, Ref. 241).

C(N.0H).C02H
Di-isonitroso-succinic Acid, , , is formed by acting upon tetra-

C(N.0H).C02H
oxysuccinic acid with hydroxylamine. It crystallizes in prisms and melts with
decomposition at 128-130° {Berichte, 16, 2985).

Amido-succinic acid (aspartic acid), C2H3(NH2) (COiH)^, and

/ CO IT

amido-succinamic acid (asparagine), CjH3(NH2) ^ ^q^ ^ttt , will

be described under malic acid, as they bear the same relation to it
that glycocoU (amido-acetic) bears to glycollic acid.

Diamido-succinic Acid, C2H2(NH2)2y rc\\ii '^ foi'^^d fro™ dibromsuccinic

acid by the action of ammonia, and also results from the diphenylhydrazine deriva-
tive of dioxy-tartaric acid through the decomposition brought about by sodium
amalgam {Berichte, 20, 245) : —

C(OH)2.C02H CH(NH2).C02H

I , yields |

C(OH)2.C02H CH(NH2).C02H

It is almost insoluble in the ordinary reagents, but dissolves in mineral acids and
alkalies, with the formation of salts, which are nearly all decomposed by water.
It separates from them as a crystalline powder. Rapidly heated, it is almost
wholly carbonized. As it contains 2 COOH groups and 2 amide groups, it is a
diglycocoU (p. 367).

Another diamido-succinic acid has been described. Its ethyl ester was obtained
by the action of alcoholic ammonia upon dibrom -succinic acid {Berichte, 15, 1848).

C(N2).C02.C2H5

Ethyl Diazo-succinic Ester, I , is obtained from HCl-ethyl

CH2.C02.C,H5
amido-succinic ester (ester of aspartic acid) by the action of sodium nitrite (p.
373). It is a dark-yellow oil, which volatilizes in steam with only partial decom-

41 6 ORGANIC CHEMISTRY.

position. Its reactions show it to be wliolly analogous to diazo-acetic ester. Wlien
boiled with water it yields nitrogen and fumaric ester. When heated, it sustains
a complicated transposition with the formation of the ester of azin-succinic acid
{Berichte, i8, 1302; ig, 2460). Zinc dust and ammonia convert it into the esters
of aspartic acid.

Cyan-succinic Acid, CjH3(CN)(C02H)2,is produced when potassium cyanide
acts upon brom-succinic ester (p. 262). The hydrogen of the CH-group, in its
diethyl ester, can be replaced by sodium and alkyls {^Berichte, 22, Ref. 267).

(2) Isosuccinic Acid, CHj.CH/pQ^TT, ethidene dicarboxy-

lic acid, methyl malonic acid, is obtained from a-chlor- and brom-
propionic acids through the cyanide {Berichte, 13, 209) : —

CH3.Ch/^N ^ ^ ^j^^Q _ CH3.CH/^g^^g + NH3.

When ethidene bromide, CHs.CHBrj, is heated with potassium
cyanide and alkalies, we do not obtain ethidene succinic acid by
the operation, but ordinary ethylene succinic acid. When malonic
esters are treated with sodium and me.thyl iodide they yield iso-
succinic acid. The latter crystallizes in needles or prisms, and is
more readily soluble than ordinary succinic acid (in 4'parts HjO).
It sublimes below 100° in plates, melts at 130°, and by further
application of heat breaks up into carbon dioxide and propionic
acid (p. 351):—

CH3.CH/gg;gg = CH^.CH^.CO.H + CO,.

When heated with water above 100° the result is the same. The
ethyl ester, C4H404(C2H5)2, boils at 196°; the methyl ester aX 179°.

Brom-isosuccinic Acid, CH3.CBr(C02H)2 is formed on heating isosuccinic
acid with water and bromine to 100°. Large deliquescent prisms, which decom.
pose readily.

4. Pyrotartaric Acids, CsHsO^ = CjHs/^q^^.

Four of these acids are theoretically possible : —

CH3 CH„.COoH CH, CH,-

1 I I I

CH.CO2H CH2 CH, and c/^^a^.

I I I 1^ ^

CH2.CO2H CH2.CO2H c^xco'h *^^^'

Pyrotartaric Acid. Glutaric Acid. Ethyl Malonic Acid. Dimethyl Malonic Acid.

(0 Pyrotartaric Acid, CH3.CH<^'^^'^q ■^, propylene di-
carboxylic acid, was first obtained in the dry distillation of tartaric

GLUTARIC ACID. 41 7

acid (mixed with pumice stone). It may be synthetically prepared
from propylene bromide, by means of the cyanide —

CH3.CH/gg^^j^ yields CH^.Ch/^O.^q^jj^

or by the action of nascent hydrogen upon the three isomeric
acids: ita-, citra-, and mesa-conic acids: CsHeO, -}- Hj = C5
H8O4. It is further formed from a- and yJ-methyl aceto-succinic
esters (made by introducing methyl into aceto-succinic esters) and
by acting on aceto-acetic esters with a-brompropionic esters, p. 400;
from ^-brombutyric acid by means of the cyanide, and by heating
pyroracemic acid, CH3.CO.CO2H, alone to 170°, or with hydro-
chloric acid to 100°. The acid consists of small, rhombic prisms,
which dissolve readily in water, alcohol and ether. It melts at 112°
and when quickly heated above 200°, decomposes into water and
the anhydride. If, however, it be exposed for some time to a tem-
perature of 200-210°, it splits into CO2 and butyric acid. It suffers
the same decomposition when in aqueous solution, if acted upon by
sunlight in presence of uranium salts.

The neutral calcium salt, CjHjO^Ca -\- zHjO, dissolves with difficulty in water.
The same may be remarked of the acid potassium salt, CjHjKO^. The ethyl ester
.boils at 21 S°. /CO

The a«%'aWa'^, CHg.CH^J „TT /-./-> >0, obtained by heating pyrotartarlc acid

above 220°, is a heavy oil, which boils at 244.9°, sinks in water and gradually
reverts to the acid (Annalen, 191, 48).

(2) Glutaric Acid, CH2<^ptt^"pq''tt, Normal Pyrotartaric

Acid, was first obtained by the reduction of a-oxyglutaric acid with
hydriodic acid. It may be synthetically prepared from trimethylene
bromide (p. 102), through the cyanide ; from aceto-acetic ester by
means of the aceto-gliitaric ester (p. 400) ; from glutaconic acid
(p. 425), and from propane tetracarboxylic acid, C3H4(C02H)4, by
the removal of 2CO2. Glutaric acid crystallizes in large mono-
clinic plates, melts at 97°, and distils near 303°, with scarcely any
decomposition. It is soluble in 1.2 parts water at 14°.

The calcium salt, CjHjO^Ca -f- 4H2O, and barium salt, Z^flfis. + sHjO,
are easily soluble in water ; the first more readily in cold than in warm water.
The ethyl ester, C5H504(C2H5)2, boils at 237°. The anhydride, C5H5O3, forms
on slowly heating the acid to 230-280°, and in the action of acetyl chloride on the
silver salt of the acid. It crystalUzes in needles, melting at 56-57° (after solidifi-
cation it melts at 36°), and boils near 285°-

Glutarimide, C3H6(CO)2NH, results by the distillation of ammo-
nium glutarate. It crystallizes in shining leaflets and melts at 152°,

35

41 8 ORGANIC CHEMISTRY.

The vegetable alkaloid piperidine, C5H10NH, is obtained from it by
distilling .with zinc dust. PCI5 and HI convert it into the base
pyridine^ CsHjN, just as succinimide yields pyrrol (p. 413), {Berichte,
16, 1683).

.(3) Ethyl Malonic Acid, CjHj.CH^f ^-^ jg obtained from a-brombutyric

ester, through the cyanide, and by the action of Na and CjHjI upon malonic
ester. It is very similar to ordinary tartaric acid, melts at 111.5° ^'I'i decomposes
at 160°, more rapidly at 170°, into butyric acid and COj. The calcium salt,
CjHjOjCa -|- HjO, forms prisms, and is more easily soluble in cold than in hot
water. Its ^//5y/ «^^7- boils at 200°. For sodium- and chlor- ethyl malonic ester,
see Berichte, 21, 2085. prr v /co H

(4) Dimethyl Malonic Acid,„j,* pCx f^Q^Ti, is obtained from o-bromiso-

butyric ester by means of potassium cyanide ; by introducing methyl into malonic
ester, and from mesitylenic acid {Berichte, 15, 581). It crystallizes in four-sided
prisms, and dissolves with difficulty in alcohol, but is rather readily soluble in water.
It is not as soluble as its isomerides. It sublimes about 120° and melts at 170°,
decomposing at the same time into COj and isobutyric acid. The barium salt
crystallizes in needles; the calcium salt is more soluble in cold than in warm
water. The ethyl ester boils at 195°.

The isomeric chlorine and bromine substitution products of the pyrotartaric
acids are produced by the direct addition of HCl, HBr and Br^, to the unsaturated
isomeric acids, C^HgO^ : itaconic, citraconic and mesaconic acids (p. 429). The
new derivatives are known as ita-, citra- and mesa-pyrotartaric acids : —

Itaconic Acid ") ( Ita- ) -,.,

Citraconic Acid Ic.HA + Br, = C,H,Br,oJ Citra- [^jScid^
Mesaconic Acid J (. Mesa- J '"'""= ""i^-

Itachlor-pyrotartaric Acid, CjHjClO^, is formed by heating itaconic acid with
fuming hydrochloric acid to 130°. It melts at 145°. When heated with water or
alkalies it passes into itamalic acid, C5H,(0H)0j. It yields paraconic acid, CjHj
Q^, with silver oxide.

Citra- or Mesa-chlorpyrotartaric Acid is obtained on treating citraconic
anhydride with cold concentrated hydrochloric acid, and by heating mesaconic
acid to 140° with concentrated hydrochloric acid. It crystallizes in plates and
melts at 129°. When boiled with water it breaks up into HCl and mesaconic
acid. Boiling alkalies change it into HCl, CO, and methacrylic acid, C^HjOj.

Fuming hydrobromic acid converts citraconic acid, its anhydride and also
mesaconic acid (at 140°) into the same brompyrotartaric Acid, CjHjBrOj. It
melts at 148°, and when boiled with water yields COj, HBr and methacrylic acid.
Itabrompyrotartaric Acid, from itaconic acid, is not so soluble in water, and
melts at 137°-

The ita-, citra- and mesa-dibrompyrotartaric acids, CjHjBrjO^, are dis-
tinguished by their different solubility in water. The ita- compound changes to
aconic acid, CjHjOj, when the solution of its sodium salt is boiled; the citra-
and mesa- compounds, on the other hand, yield brom-meth acrylic acid (p. 240).

Nascent hydrogen causes all these substitution derivatives to revert to ordinary
pyrotartaric acid.

ADIPIC ACID. y^ig

S. Acids, C,Hi„0, = C.Hj/^g^H

Nine are possible and eight known: (i) Normal Butandicarboxylic acid or
Adipic acid. (2) a- and /3-Methyl glutaric acids (isomerides), derived from

glutaric acid, CHj(^ CH^ CO*H' ^3) Symmetrical and unsymmetrical dimethyl

succinic acids and ethyl succinic acid (isomerides) derived from succinic acid,
CHj.COjH

I . (4) Propyl, isopropyl and methyl- ethyl malonic acids (isomerides),

CHj.COjH
derived from malonic acid.

Symmetrical dimethyl succinic acid, like other symmetrical disubstituted suc-
CHX.COjH
cinic acids, I (as dibromsuccinic acid (p. 414), dioxysuccinic acid or

CHX.COjH
tartaric acid, diethyl-, methylethyl-, diisopropyl-, diphenyl-succinic acid, etc.),
exists in two modifications. These have the same structural formulas, and are,
therefore, to be regarded as alloisomeric (p. 50). In the case of dioxysuccinic
or tartaric acid (see this) there are two active and two inactive forms (one capa-
ble of division, the other not). They are striking examples of the facts that
vant' HofF endeavors to explain by his theory of asymmetric carbon atoms , (p.
63). The various dialkyl succinic acids also contain asymmetric carbon atoms,
and show some analogy to /a/'a-tartaric (racemic acid) and anti- or ?kmo- tartaric
acids. On this account their isomerism is presumed to be due to the same cause,
and in consequence the modification with the higher melting point, and dissolving
with greater difficulty, is known as the para form, while the more soluble variety,
with lower melting point, is known as the anti form (Bischoff, Berichte, 20, 2990;
21, 2106). This assumption seems rather questionable, as no one has yet suc-
ceeded in converting any of the dialkyl-succinic acids, which are always inactive,
into an active form {Berichte, 22, 1819).

Another explanation, emphasizing the similarity that may be traced between the
two different modifications of the dialkylsuccinic acids and maleic and fumaric
acids, calls the one form " fumaroid," and the other " maleinoid" (Berichte, 21,
3169). The isomerism is supposed to be due to the same cause that underlies the
isomerism of fumaric and maleic acids, van't Hoff' attributes it to the " fixation "
of two doubly-linked carbon atoms. This would, then, establish the " fixation " of
carbon atoms united by single bonds. The result would be the removal of one of
the fundamental ideas of the far-reaching theory of van't Hoff.

A third attempt to elucidate the existing difficulty is known as the " Theory oi
dynamical Isomerism" {Berichte, 23, 624). It, probably, finds expression in the
fact that it seeks to account for isomerides that do not exist [Berichte, 23, 1606).

(i) Adipic Acid, CeHioOi, was first obtained by oxidizing fats
with nitric acid. It is synthetically prepared by heating /?-iod-
propionic acid, with reduced silver, to 130-140° : —

CHj.CHj.COjH
2CH2l.CH2.C0,H + Ag2 = I -f 2AgI.

CH2.CH2.CO2H

It is also obtained by the action of nascent hydrogen upon hydro-
muconic acid, CsHsOi (p. 430), and by oxidizing sebacylic acid
with nitric acid (along with succinic acid), and by the separation of

420. ORGANIC CHEMISTRY.

aCOj from tetramethylene tetracarboxylic acid, CiHeCCOjH)!. It
crystallizes in shining leaflets or prisms, which dissolve in 13 parts
of cold water, and melt at 148°.

(2) a-Methyl Glutaric Acid,CH^{^^^r^^^^^Q ^, is obtaiaed from methyl

aceto-acetic ester, by the action of /3-iodpropionic ester and the elimination of
ketone (p. 400), by the reduction of saccharon with hydriodic acid, and by the
action of KCN upon Isevulinic acid. It melts at 76°. It yields methylpenthio-
phene {Berichte, 19, 3270) when heated with PjSj.

(3) The /3-acid, CHj.CH^ Ch'' CO H' ^'°™^ ethidene dimalonic acid (Anna-
len, 218, i6l), melts at 86°, and forms an anhydride, which melts at 46° and boils
at 283°. /CO H

(4) Ethyl Succinic Acid, CjHj.CjHj;' j^q'^tt, results from ethyl aceto suc-
cinic ester, by elimination of ketone, also from a- and j3-ethyl ethane tricarbonic
ester, C2H5.C2H2(COjR)3, when boiled with sulphuric acid (Berichte, 23, 638).
It melts at 98°. When heated it yields a liquid anhydride, CjHjOj, boiling at
243.°. CH,.CO,H

(5) Unsymmetrical Dimethyl Succinic Acid, I , is pro-

(CHsl.-C.CO^H

duced from isobutylene tricarboxylic acid, (CHg)2.C^ pji/rn tj\ (from malonic

ester and a-bromiso-butyric acid, Berichte, 18, 2350 ; 23, 636), by splitting off COj ;
when copaiva oil is oxidized {Berichte, 18, 321 1) ; and from isobutylene bromide
by means of the dicyanide (Berichte, 22, 1739). It crystallizes in prisms, melts at
140°, and at higher temperatures, passes into the anhydride, CjHjOj, fusing at
29°, and boiling at 230°. CHj.CH.COjH

(6) Symmetrical Dimethyl Succinic Acid, | , exists in two

CHj.CH.COjH
alloisomeric forms, the malelnoid (anti-) form, and the fumaroid (para-) modifica-
tion. These (their esters) are produced as follows : By the elimination of two
molecules of carbon dioxide from dimethyl ethane tetracarboxylic acid ; by the
saponification of a/3-dimethyl-ethane tricarboxylic esters, (CH3)j.C2H(COjR)3,
with hydrochloric or sulphuric acid (Bischoff, Berichte, 22, 389 ; 23, 639) ; from
0(3-dimethyl aceto succinic ester by the elimination of acid (p. 400) ; by heating
(i-brompropionic acid, CH3.CHBr.CO2H, with reduced silver (Berichte, 22, 60),
or more readily by the action of potassium cyanide upon a-brompropionic ester
(ZeWosVy, Berichte, 21,3160); also by the reduction of dimethyl fumaric acid,
pyrocinchonic acid (p. 430) with sodium amalgam or hydriodic acid (Berichte, 20,
2737 ; 23, 644). Both symmetrical dimethyl succinic acids are produced in all of
these syntheses. They are separated by crystallization from water.

The^«ra-acid (analogous to racemicand fumaric acids) is soluble in 96 parts of
water at 14°. It forms needles and prisms, melting at I92°-I94°. They sustain
a partial loss of water upon melting. If the acid be heated for some time to 1 80°-
200°, it yields a mixture of the anhydrides, C^HgOj, of the para- and a«/j acid.
With water each reverts to its corresponding acid. When acetyl chloride acts on
the /3?-a-acid, its anhydride is the only product. It crystallizes from ether in
rhombic plates, melts at 38°, distils at 234°, and unites with water to form the
pure para-acid (Berichte, 20, 2741 ; 21, 3171 ; 22, 389 ; 23, 641).

If the para-2iC\&. be heated to 130° with bromine, it yields pyrocinchonic acid,
CjHjOj (p. 430). Both acids, when digested with bromine and phosphorus,
yield the same brom-dimethyl succinic acid, CjH^BrO^, melting at 91°. Zinc and

METHYL ETHYL SUCCINIC ACID. 42 1

hydrochloric acid change it to the anii-acid [Berichte, 22, 66). The ethyl ester oi
the paraacid (from the silver salt) boils at 219° ; the methyl ester at 199°.

The 3«ri-acid (analogous to anti-tartaric acid and malelc acid) dissolves in 33
parts of water at 14°. It crystallizes in shining prisms, and fuses, after repeated
crystallizations from water, at 120-123°. It yields its anhydride, CjHjOj, when
heated to 200°. This melts at 87°. It regenerates the acid with water. If the
anti-acid be heated with hydrochloric acid to 190°, it becomes the para-acid. The
methyl ester boils at 200° ; the ethyl ester at 222°- When the anti-acid is etherified
with HCl, it yields a mixture of the esters of the anti- and para-acid [Berichie, 22,
389, 646; 23, 639). „„ ^

(7) Methyl-ethyl Malonic Acid, ^^s"\c(C02H)2, melts at 118°, and

decomposes into CO 2, and methyl-ethyl acetic acid.

(8) Propyl Malonic Acid, C3H,.CH(C02H).^, obtained from malonic acid,
and by the reductionof dichloradipic acid [Berichte, 18, 852), melts at 96°, and at
150° decomposes into COj, and normal valeric acid.

(9) Isopropyl Malonic Acid, CjH^.CH^^ COW ''°™ sodium malonic ester,
melts at 87°, and at I7S° breaks up into COj and normal valeric acid.

6. Acids, CjHijO^ = C5Hi|,(C02H)2. .^^ CH CO H

(i) Normal Pentan-dicarboxylic Acid, CHj^' „TT*'pTT^'pQ^rT, a-pimelic

acid, first prepared by oxidizing suberone, CjHjjO (p. 422), by heating furonic
acid, CjHjOj, with HI, and in the oxidation of fats with nitric acid, can be ob-
tained synthetically from trimethylene bromide and malonic ester by heating pen-
tamethylene tetracarboxylic acid, which is the first product of the reaction {^Berichte,
18, 3249). It consists of large laminas or prisms, melting at I02°-I04°.

/PT-T CO T-T "

(2) ;3-Ethyl Glutaric Acid,C2H5.CH.;^ ^^' ^1^^ ^,propylidene diacetic acid ,

from propylidene dimalonic acid (from propionic aldehyde and malonic acid)
{Annalen, 218, 167), melts at 67°. /CHfCH 1 CO H

(3) Symmetrical Dimethyl Glutaric Acid, CH^^^ CHICh'I CO^H' '^ P™"
duced in two alloisomeric forms when methylene iodide acts upon a-cyanpropionic
ester. These melt at 103° and 128°. The first (regarded as trimethyl-succinic
acid") has also been obtained from methyl malonic ester.and a-bromiso-butyric ester
{^Berichte, 22, 2823; 23, 1600). Symmetrical diphenyl glutaric acid has been
prepared in but one variety [Berichte, 22, 3289).

/PfT CO T-T

(4) Propyl Succinic Acid, CjH^.CH^ (-.Q^u 2 ^ from propyl-ethylene

tricarboxylic ester {Annalen, 214, 54), crystallizes in warty masses, and melts at

(5) Isopropyl Succinic Acid, (0113)2. CH.CH(^(^„ 2^ 2 , Pimelic Acid,

was first prepared by fusing camphoric acid, and may be synthetically obtained
from aceto-acetic or malonic esters (^Berichte, 16, 2622 ; Annalen, 220, 271). It
forms crusts, is readily soluble in water, alcohol and ether, melts at 114°, and on
stronger heating, yields an anhydride, boiling at 250°.

CH3.CH.CO2H

(6) Methyl Ethyl Succinic Acid, | , exists in two alloiso-
^ ' C2H5.CH.CO2H

meric modifications. It results after heating a^-methyl-ethyl ethylene tricarboxylic
ester with sulphuric acid. The /«ro-acid melts at 168°, and when heated for

422 ORGANIC CHEMISTRY.

some time passes into the anhydride of the anti-variety.' The anti- or OTMo-acid
melts at 84°, and yields a liquid anhydride, boiling at 243°.

(7) Normal Butyl Malonic Acid, C4,Hg.CH(COjjH)2,ha| been obtained from
a-bromcaproio acid and potassium cyanide. It melts at 101°, and at 140° decom-
poses into CO 2 and caproic acid.

(8) Isobutyl Malonic Acid, (CH3)2.CH.CH2.CH(C02H)2, from malonic
ester, melts at 107°.

(9) Diethyl Malonic Acid, (C2H5)2C(C02H)2, from ethyl malonate, melts
at 121°, and above 170°, decomposes into COj and diethyl acetic acid.

7. Acids, CgH^p, = CjHijCCOjH)^.

(i) Suberic Acid, CjHjjOj, probably of normal structure, is obtained by boil-
ing corks, or fatty oils, with nitric acid {Berichle, 13, 1165). It is soluble in 200
parts of cold water, readily in hot water, alcohol and ether. It crystallizes in
needles or plates, melting at 140° and subliming without decomposition. Its
ethyl ester boils at 280-282°. Hexane, CjHjjj, and Suherone, C,HjjO =
CW (""HT Pf-T
prr^- 2- 2\.co (Aunalen, 211, 117), result when its calcium salt is distilled.

Suberone is a liquid boiling at 1 80°. Its odor resembles that of peppermint.

CH2.CH(CH3).C02H

(2) osaDimethyl Adipic Acid, | , has been prepared by

CH2.CH(CH3).C02H
the action of reduced silver upon /3bromisobutyric acid. It occurs in two allo-
isomeric modifications. One melts at 139°, the other is a liquid (i?ifnV.4^^, 23,

295)' /P/^PTT ^ CO TT

(3) Trimethyl Glutaric Acid, CHj;^ rHrCH S CO H' '^ formed, together

with tetramethyl succinic acid (p. 423), when a-bromisobutyric acid is heated with
reduced silver. It melts at 97° and sublimes without decomposition. It is not
volatile with steam. When the acid is heated for some time, or acted upon with
acetyl chloride, it changes to its anhydride, CgHji^Oj, melting at 96°, and boiling
at 262° {Berichte, 23, 300). C^Hs.CH.COjH

(4) Symmetrical Diethyl Succinic Acid, | , exists, like other

C2H5.CH.CO2H
symmetrical dialkylsuccinic acids, in two alloisomeric modifications (p. 419). These
are obtained: By the elimination of 2CO2 from diethylethane-tetracarboxylic acid,
{C^^jZ^{CO^)^ [Berichte, 21, 2085) ; by heating xeronic anhydride (p. 431) with
hydriodic acid (Berichte, 20, Ref 416; 21, 2105). The diethyl ester results upon
heating a-brombutyric ester with silver (Hell, Berichte, 22, 67), and upon boiling
a;3diethyl-ethane-tricarboxylic ester, (C2H5)2C2H(C02R)3, with sulphuric acid
[Berichte, 21, 2089; 23, 650). The para-acid is soluble in 162 parts of water
at 23°. It crystallizes in needles and melts about 189-192°. It then loses water. .
The anti-acid is soluble in 41 parts of water at 23°, and melts at 129°. Heated
to 240° the anti- acid forms a liquid anhydride, CJHJ2O3, boiling at 246°, and
reverting to the acid when treated with water. The para-acid, after long heating
at 240°, also yields the anhydride of the anti-acid. Vice-versS, the a«^z-acid is
changed to the para-acid when heated to 200° with hydrochloric acid or water,
[Berichte, 21, 2102; 23, 656).

There is a third diethylsuccinic acid. It is supposed to be symmetrical [Be-
richte, 23, 628). It melts at 137.5°. It is very probably ethyl-methyl-glutaric
acid [Berichte, 23, 1606). CH2.CO2H

(5) Unsymmetrical Diethyl Succinic Acid, | , has been

(C2H,)2C.C02H
obtained from a-diethyl-ethane-tricarboxylic ester. It melts at 86°. It forms an
anhydride, boiling about 71° [Berichte, 23, 651).

For two additional ethyl-dimethyl-succinic acids, see Berichte, 23, 1606.

UNSATURATED DICARBOXYLIC ACIDS. 423

(CH3)2.C.C02H

(6) Tetramethyl Succinic Acid, | , is formed, together with

(CH3)2.C.CO,H
trimethyl glutaric affid (p. 422), when a-bromisobutyric acid (or its ethyl ester) is
heated with silver. It is volatile with steam. It melts about 190-192°. It parts
quite readily with water and passes into the anhydride, CgHuOj, melting at
147°, and boiling at 230° {Berichie, 23, 297).

(7) n-Pentyl Malonic Acid,»C5Hjj.CH(C02H)j, from brom-oenanthylic ester
and potassium cyanide, melts at 82°. It decomposes above 129° and splits off
CO,.

Symmetrical Diisopropyl Succinic Acid, | (?), appears in

CjH^j.CH.CO^H
two alloisomerides when a-bromisovaleric acid, CjHj.CHBr.COjH, is acted upon
with silver. The one variety volatilizes with steam and melts at 178°. It readily
passes into an oily anhydride on healing. The other is non-volatile, melts at 197°,
and sublimes undecomposed above 210° [Berichte, 22, 48).

Higher dibasic acids are produced by oxidizing the fatty acids or oleic acids
with nitric acid. They always form succinic and oxalic acids at the same time.
The acids of the series, CnH2n— 4O2 (p. 244), usually decompose into the acids
CnH2„04, when oxidized with fuming nitric acid. The mixture of acids that
results rs separated by fractional crystallization from ether; the higher members,
being less soluble, separate out first [Berichte, 14, 560).

Lepargylic Acid, CgfljjO^, Azelaic Acid, is best prepared by oxidizing
castor oil [Berichte, 17, 22:4). It crystallizes in shining leaflets, resembling
benzoic acid. It melts at lo5°, and dissolves in 100 parts of cold water.

Sebacic Acid, CijHjgO^, is obtained by the dry distillation of oleic acid, by
the oxidation of stearic acid and spermaceti, and by fusing castor oil with caustic
potash. It crystallizes in shining laminae, which melt at 127°.

Brassylic Acid, CjjHjqOj, obtained by oxidizing behenoleic and erucic acids,
melts at 108°, and is almost insoluble in water.

Roccellic Acid, Cyfi.^j^^, occurs free in Roccelta tinctoria. Prisms melting
at 132°.

Cetyl Malonic Pi.z\di,.C^^^^^Q,^^^^.ZB.{^0^)^, from malonic ester
and cetyl iodide, melts at 121°, and immediately breaks down into CO.^ and
stearic acid.

UNSATURATED DICARBOXYLIC ACIDS, C,,H2„_A-

The acids of this series bear the same relation to those of the
oxalic acid series that the acids of the acrylic series bear to the
fatty acids. They can be obtained from the saturated dicarboxylic
acids by the withdrawal of two hydrogen atoms. This is effected
by acting on the monobrom-derivatives with alkalies : —

CoHjBrCCOaH)^ + KOH = C^Vi.^{0:)^n)^ + KBr + H^O;
Bromsuccinic Acid. Fumaric Acid.

424 ORGANIC CHEMISTRY.

or, the same result is reached by letting potassium iodide act upon
the dibrom-derivatives (p. 235). Thus, fumaric acid is formed
from both dibrom- and isodibrom-succinic acids:-*

C,H,Br,(C02H), + 2KI = C,H,(CO,H), + 2KBr + I,;

and mesaconic acid, C3H4(C02H)2, from citra- and mesa-dibrom-
pyrotartaric acids, C3H4Br2(C02H)2. jfs a general thing the unsatu-
rated acids are obtained from the oxydicarboxylic acids by the
elimination of water (p. 235).

The esters of these acids are obtained in the condensation of
malonic esters with aldehydes : —

CH3.CHO + CHjfCOjR), = CH3,CH:C(C02R)2 + H^O.

Ethidene malonic esters are formed at the same time ; from them
we can get saturated dicar boxy lie acids {Afinalen, 218, 156).

The union is more easily brought about by the action of sod-malonic
ester {Berichte, 20, Ref. 258, 552).

The isomerisms of the acids of this series offer peculiar relations, as yfet unex-
plained. The lowest member of the series has the formula C3H2(C02H)j. This
can be structurally represented in two ways : —

CH.COjH CHj

(I) II and (2) II .CO^H.

CH.CO2H C(

\CO2H

The first would correspond to succinic acid, the second to the iso-acid. Two
acids — maleic and fumaric — with the formula C2H2(C02H)2, are known. Owing
to its ability to form an anhydride, maleic acid is supposed to have the first struc-
tural formula. (The supposition that a divalent carbon atom is present in the acid
offers no explanation for its behavior.) The second formula is then ascribed to
fumaric acid. Certain synthetic methods (p. 425) used in forming these acids
argue for the preceding views. Yet most of the transpositions suffered would seem
to show that the acids have the same structural formula.

This is evidently a case of alloisomerism (p. 50), which our present structural for-
mulas fail to represent. Various hypotheses have been advanced for the explana-
tion of the peculiar isomerism of these two acids [Annalen, 239, 161), but have,
to some extent, been, abandoned, f.^., the supposition that the relations existing
between the acids (fumaric and maleic) were similar to those existing between
racemic and inactive tartaric acid, has been disproved by a determination of the mole-
cular weight according to Raoult (Patern6, Berichte, 21, 2156). Another suggestion
is that the isomerism is due to a difference of structure in the two carboxyl groups,
and that maleic acid should be viewed as a dioxylactone {ibid.). A more prom-
ising indication for the solution of these difficulties, seems to lie in the introduction
of representations upon the spatial relations of the atoms in accordance with the
view or hypothesis of LeBel and van't Hoff, lately elaborated by J. WisHcenus (see
pp. 51, 52, and (Berichte, 20, Ref. 448; 21, Ref. 501).

UNSATURATED DICARBOXYLIC ACIDS. 425

This view ascribes to fumaric acid the axial-symmetric, and to maleic acid the
plane-symmetric configuration, briefly represented as follows : —

H*^C— CO.OH HO.OC— C— H

II and II

H— C— CO.OH H— C— CO^H

Maleic Acid. Fumaric Acid.

The arrangement of the two carboxyls upon the same (corresponding) side gives
maleic acid the power of forming an anhydride. In fumaric acid the carboxyls
oppose each other; an anhydride cannot be formed.

I. Fumaric and Maleic Acids, C^B.^^^^^, are obtained by
distilling malic acid : —

C,H3(0H)(C0,H), = C,H,(CO,H), + H,0;

fumaric acid remains in the residue, while maleic acid and its anhy-
dride pass 'over into the receiver {Berichte, 12, 2281). The last
two are formed in especially large quantities on rapidly heating
malic acid, whereas, by prolonged heating at i4o°-i5o°, fumaric
acid is the chief product (^Berichte, 18, 676). If maleic acid be
heated for some time at 130° it changes to fumaric acid ; when the
latter is distilled it decomposes into water and maleic anhydride.
Maleic acid is only completely converted into fumaric acid when it
is heated, either alone, or in aqueous solution, to 200-201°, in a
sealed tube. Fumaric acid is fully changed to maleic anhydride .
by heating to 160° with P2O5 (Tanatar). For the conversion of
maleic into fumaric acid, by means of bromine and hydrobromic
acid, consult Berichte, 21, Ref. 501, and Annalen, 248, 342.
Acetylene is obtained by the electrolysis of a concentrated solution
of the sodium salts of the two acids (p. 87).

We can obtain maleic acid (its ester) synthetically by heating dichloracetic
ester, CHClj.COj.CjHj, with silver or sodium. Fumaric acid is formed from
a;8-dichlorpropionic acid (which yields a-chloracrylic acid, CH2:CC1.C02H, p.
237), by the action of potassium cyanide and caustic potash. Both syntheses
indicate that the first formula properly falls to maleic acid and the second to
fumaric (p. 424). This conclusion is contradicted by the formation of maleic acid
from j8-dibrompropionic acid (which yields a bromacrylic acid, CH2:CBr.C02H,
p. 237), by the action of potassium cyanide and potash, and fumaric acid from
chlorethenyl tricarboxylic ester, C2H2Cl(C02.C2Hg)3 {^Berichte, 13, 100 and
2163) ; 'also, by the fact that fumaric acid is formed from dichloracetic and malonic
acids {^Annalen, 218, 169). The action of sodium ethylate upon abromisobu-
tyric acid produces ct-ethoxy-isosuccinic acid (see Isomalic Acid). /3-Ethoxy-iso-
succinic ester and methylene malonic ester are produced by the interaction of
methylene iodide and sodium malonic ester.

Fumaric Acid occurs free in many plants, in Iceland moss, in
Fumaria officinalis and in some fungi. It is produced by heating
dibrom- and isodibrom-succinic acids with a solution of potassium
36

426 ORGANIC CHEMISTRY.

iodide; and from monobrora- and sulpho-succinic acids by fusion
with potash. It may be prepared by boiling brom-succinyl chloride
with water {Berichte, 21, Ref. 5). It is almost insoluble in water.
Mineral acids precipitate it from solutions of its alkali salts as a
white crystalline powder. It crystallizes from hot water in small,
striated prisms. It has a very acid taste, and dissolves readily in
alcohol and ether. It melts with difficulty, sublimes at 200°, form-
ing male'ic anhydride and water. Sodium amalgam, hydriodic acid
and other reducing agents convert it into succinic acid. Metallic
zinc combines with fumaric acid in the presence of water, forming
zinc succinate : C4H4O4 -|- Zn ^ CiH^OiZn.

Fuming hydrobromic acid at 100° converts fumaric into mono-
bromsuccinic acid. At ordinary temperatures it combines with
bromine (and water) very slowly, more rapidly on heating to 100°,
yielding dibromsuccinic acid. When fumaric acid (also maleic
acid, Berichte, 18, 2713) is heated with caustic soda to 100°, or
with water to 150-200°, it passes into inactive malic acid, which,
at 135°, decomposes into water and maleic acid. The esters of
fumaric and maleic acids pass into alkyloxysuccinic acids {Berichte,
18, Ref. 536) when heated with sodium alcoholates. On oxidizing
the acid with MnOjK it yields racemic, whereas, maleic acid forms
inactive tartaric acid {Berichte, 14, 713).

With the exception of the alkali, all the salts of fumaric acid dissolve with diffi-
• culty in water. The silver salt, C^HjO^Ag^, is perfectly insoluble; hence, silver
nitrate will completely precipitate fumaric acid from even dilute solutions.

The esters are obtained from the silver salt by the action of alkyl iodides, and
by leading HCl into the alcoholic solutions of fumaric and maleic acids {Berichte,
12, 2283). They are also produced in the distillation of the esters of brom-suc-
cinic acid, malic acid and aceto-malic acid (^i??-«V^/?, 22, Ref. 813). They unite
just as readily as the esters of maleic acid with 2Br (forming esters of dibromsuc-
cinic acid).

The methyl ester, C2H2(C02.CH3)2, forms white needles, melting at 102°, and
boiling at 192°. The ethyl ester is liquid, and boils at 218°. It can be obtained
by the action of PCI3 upon esters of malic acid.

Maleic Acid crystallizes in large prisms or plates, is very
easily soluble in cold water, and possesses a peculiar taste. It
melts at 130° and distils at 160°, decomposing partially into the
anhydride and water. Heated for some time at 130°, or boiled
with dilute sulphuric acid, or nitric acid, with HBr and til, it
changes to fumaric acid. Nascent hydrogen converts it into ordi-
nary succinic acid. Metallic zinc dissolves in aqueous maleic acid
without evolving hydrogen, and forms zinc maleate and acid zinc

SllCCin3.t6 '

3C4HP, + 2Zn = C,H,0,Zn + (C,HA)2H2Zn.

Fuming hydrobromic acid combines with maleic acid at 0° and
yields monobrorasuccinic acid ; an equivalent of fumaric acid forms

UNSATURATED DICARBOXYLIC ACIDS. 427

at the same time. Bromine (and water) at ordinary temperatures
converts the acid into isodibrom-succinic and fumaric acids.

The esters are produced in the same manner as those of the preceding acid.
Traces of iodine will change them, on warming, into esters of fumaric acid. The
latter also result in conducting HClgas into the alcoholic solutions of maleic acid.
Bromine converts them into esters of dibrom-succinic acid ; fumaric acid very
probably appears at first.

The methyl ester, C2H2(C02.CH3)2, is a liquid, and boils at 205°- The ethyl
ester boils at 225°.

Maleic anilide separates when aniline acts upon aqueous maleic acid. All the
derivatives of this acid react similarly, while fumaric acid and its derivatives do not
enter such a combination (jBerichte, 19, 1375. Compare Annalen, 239, 137).

Maleic Anhydride— Maleyl Oxide, C,YiS^^=C,Yi.^(^^0.

This is produced by distilling maleic or fumaric acid, or more
readily by heating maleic acid with acetyl chloride (p. 402) ; it is
purified by crystallization from chloroform {Berichte, 12, 2281, and
14, 2546). It consists of needles or prisms, which melt at 53° (60°)
and boil at 202° (196°). It regenerates maleic acid by union with
water, and forms isodibromsuccinic anhydride when heated with
bromine to 100°.

Brom-malelc Acid, C^HgBrO^, is produced by boiling barium dibromsuccinate
or the free acid with water. It consists of prisms, melting at 128°. Brom-fumaric
Acid, CjHjBrOj, .called isobrommaleic acid, is formed, the same as the preceding,
from isodibromsuccinic acid, or its barium salt, or by the addition of HBr to ace-
tylene dicarboxylic acid (p. 431). It consists of very soluble leaflets, which melt
at 179°.

These two brom-acids conduct themselves toward bromine and HBr the same
as maleic and fumaric acids. When boiled with HBr brommaleic acid is con-
verted into bromfumaric acid; its esters, too, change to those of bromfumaric acid
when they are heated with iodine. Sodium amalgam changes both to fumaric and
subsequently to succinic acid. By distillation, both yield water and brommaleic
anhydride, C^HBrOj. The latter readily unites with water, forming brommaleic
acid [Annalen, 195, 56).

Dibrom-maleic Acid, C2Br2(C02H)2, is obtained by acting on succinic acid
with Br, or by the oxidation of mucobromic acid with bromine water, silver oxide
or nitric acid. It is very readily soluble, melts at i2o°-i25°, and readily forms
the anhydride, C2Br2(CO)20, which melts at 11$°, and sublimes in needles (Be-
richte, 13, 736). Its half-aldehyde is the so-called mucobromic acid,C4H2Br203=

C^Brj^pTT^ , which results from the action of bromine water upon pyromucic

acid. It crystallizes in glistening laminae, and melts at 120°. When oxidized it
is converted into dibrom-maleic acid ; baryta changes it to malonic, dibrom-acrylic
and brompropiolic acids.

Thi dialdehyde of dibrom-maleic acid, C^Brj/^ (-,„„, is produced when brom-
ine water acts upon dibrompyromucic acid, C^HjEr^Oj. It melts at 88°, and
when oxidized yields mucobromic acid.

428 ORGANIC CHEMISTRY.

CCl.CO
Dichlormaleiic Acid, C^CIJCO^U)^. Its imide, \\ >NH, is obtained

CCl.CO
when the perchlorpyrocoU and succinimide (p. 412) are heated in a current of
chlorine. It consists of needles melting at 179°. Boiling caustic potash converts
the imide into dichlormaleic acid. This consists of deliquescent needles, which
on the application of heat pass into the ankydride, C 2 CI 2 (CO) 2 O, which melts at
120°. When the imide is heated with water CO2 splits off and a-dichloracrylic
acid is produced [Berichte, 16, 2394; 17, 553). Potassium nitrite converts the
imide into an analogue of nitranilic acid [Berichle, 22, 33).

PCI5 converts succinic chloride into two isomeric dichlormaleic chlorides, C4CI5O,
from which the acid and anhydride can be obtained [Berichte, 18, Ref. 184).
The half-aldehyde of dichlormaleic acid is the so-called mucochloric acid,

CjCljQ PJ-. TT. This is obtained when chlorine water acts upon pyromucic acid.

It melts at 125°. Alkalies convert it into formic and a-dichloracrylic acid.

Methylene Malonic Acid, CH^-.C^f^fJ^^ (p. 424), is hypothetical and iso-
meric with fumaric and maleic acids. It cannot be obtained free. Its diethyl
«^i»;-, C^H204(C2H5)2, is produced when i molecule of methylene iodide and
2 molecules of sodium ethylate act upon I molecule of malonic ethyl ester
(together with ;8-ethoxy iso-succinic ester, C2H5.0.CH2.CH(C02R)2 (Berichle,
23, 194; 22, 3294). Under diminished pressure it distils as a mobile, badly-
smelling oil. If allowed to stand, it soon changes to a white, solid mass,
(CgHjjO^jj. The liquid ester deports itself like an unsaturated compound. It
unites with bromine. When saponified with alcoholic potash it takes up alcohol
and becomes /3-ethoxy-isosuccinic acid, C2H5.0.CH2.CH(C02H)2.

2. Acids, C5H13O4 = C3H4(C02H)2.

Six unsaturated dicarboxylic acids of this formula are known : ethidene malonic,
methylene succinic, glutaconic, itaconic, citraconic and mesaconic acid ; the struc-
ture of the last three is yet in doubt. The so-called vinylmalonic acid, obtained
from ethylene bromide and the ester of malonic acid, is identical with a-trimethy-
lene dicarboxylic acid, derived from trimelhylene.

Ethidene Malonic Acid, CH3.CH:C(C02H)2, is only known in its ethyl
ester. This is formed by the condensation of malonic ester with acetaldehyde
on heating with acetic anhydride (p. 424). It boils at 220°, and at 118-120°
under a pressure of 21 mm. When saponified with baryta water it yields an
oxydicarboxyhc acid, C3H5(0H)(C02H)2. It combines with malonic ester on
heating, and becomes ethidene dimalonic ester.

The condensation of malonic ester with chloral maybe effected by heating them
with acetic acid anhydride, the product being the diethyl ester of Trichlor ethi-
dene tnalonic acid, CCls.CH:C(C02H)2, a thick oil, boiling about 160° under 23
mm. pressure.

CHjiC.COjH

Methylene Succinic Acid, | , is probably /3-trimethylene dicar-

CHj.COjH
boxylic acid (see this), inasmuch as it is produced from malonic ester and a-brom-
acrylic ester (Berichle, 20, Ref. 47).

Glutaconic Acid, CH^^^^'^q ^^ , arises in the saponification of the dicar-

UNSATURATED DICARBOXYLIC ACIDS. 429

boxy-glutaconic ester (obtained from the ester of malonic ester and chloroform,
Annalen, 222, 249). It melts at 132°. Sodium amalgam converts it into glutaric
acid.

PCI5 converts acetone dicarboxylic acid (p. 435) into Chlorglutaconic Acid,

CCl^ PjT^PQ |t , melting at 129°, and when acted upon by alcoholic potash,

passing into glutinic acid (p. 432) {Berichte, 20, 147).

Citraconic and itaconic acids, judging from their behavior, bear the same rela-
tions to mesaconic acid that maleic sustains to fumaric acid. They yield anhy-
drides, whereas mesaconic acid when distilled passes into citraconic anhydride.

Citraconic and itaconic acids are obtained in the distillation of citric acid.
Aconitic acid, C,H3(C02H)j (see this), is produced at first and by the subse-
quent withdrawal of water and COj it yields itaconic and citraconic anhydrides :
CgHjOg = CjH^Oj -f" HjO -|- CO2. Both anhydrides are present in the filtrate.
The first yields itaconic acid by union with water [Be'richU, 13, 1541.) When free
itaconic acid is distilled it yields water and citraconic anhydride, which changes to
the acid on warming with water. If citraconic acid be heated for some time to
100° or its aqueous solution to 130°, itaconic acid is produced. Boiling dilute
nitric acid or concentrated haloid acids convert citraconic into mesaconic acid.

Citra-, ita- and mesaconic acids unite with chlorine, bromine and the halogen
hydrides, yielding derivatives of pyrotartaric acid (p. 416); the first two acids
react in the cold ; mesaconic acid (like fumaric acid) only on the application of
heat. Nascent hydrogen converts them all into the same pyrotartaric acid. The
electrolysis of their sodium salts (p. 87) decomposes them, according to the
equation : —

CjHJCO.H), = C3H, + 2CO, + H„

when ordinary allylene, CHg.C • CH, results from citra- and itaconic acid, and iso-
allylene (p. 89) from itaconic acid.

Citraconic Acid, CjHjOj, is obtained from its anhydride by heating the latter
with water. It crystallizes in glistening prisms, which deliquesce in the air, and
melt at 80°- It breaks up by distillation into its anhydride and water. Citraconic
Anhydride, CjHjOj, is also formed by heating the acid with acetyl chloride, and
is obtained li>y the repeated distillation of the distillate (see above) resulting from
citric acid. It is an oily liquid which boils at 213-214° with partial transformation
into xeronic anhydride (see below) ; it combines to citraconic acid when heated
with water.

Itaconic Acid, C5H5O4, is best obtained by heating citraconic anhydride with
3-4 parts water to 150°. It crystallizes in rhombic octahedra, dissolves in 17 parts
of H^O at 10°, melts at 161° and decomposes when distilled into citraconic anhy-
dride and water. Itaconic acid gives the maleic acid reaction with aniline (p. 427
and Berichte, 19, 1383). Itaconic Anhydride, CjHjOj, is prepared from the
acid on heating with acetyl chloride (^Berichte, 13, 1541). It crystallizes from
chloroform in rhombic prisms, melts at 68° and distils unaltered under diminished
pressure, but at ordinary pressures changes to citraconic anhydride. It dissolves in
water with formation of itaconic acid.

Mesaconic Acid, C5H5O4, is prepared by heating citra- and itaconic acid with
a little water to 200° and may be obtained by evaporating citraconic anhydride with
dilute nitric acid {Annalen, 188, 73). It dissolves with difficulty in water (47
parts at 18°), crystallizes in glistening needles or prisftis, melts at 202° and at 205°
decomposes into citraconic anhydride and water.

Consult Berichte, 14, 2785, for the esters of citra-, ita-, and mesaconic acids.

43° ORGANIC CHEMISTRY.

3. Acids, C^HsOi == C^H^CCO^H),.*

AUyl Malonic Acid, CHjiCH.CH^.CH^COjH)^, is obtained from malonic
ester by means of allyl iodide. It crystallizes in prisms and melts at 103° [Anna-
len, 216, 52). Hydrobromic acid converts it into carbovalerolactonic acid, CjH jOj
(the lactone of 7-oxyproprio-malonic acid) (p. 352) : —

-COjH CH3.CH.CHj.CH.COjH
CHj:CH.CH„.CH( yields | |

^COjH O CO

The latter is a thick liquid, readily soluble in water. When heated to 200° it
breaks up into CO, and valerolactone (p. 363).

Propylidene Malonic Acid, C2H5.CH:C(C02H)2, is produced by the action
of malonic acid upon propionic aldehyde. It breaks down into carbon dioxide
and propylidene acetic acid (p. 241), when distilled.

Hydromuconic Acid exists in a stable and an unstable modification {Berickte,
23, Ref. 231) :—

COjH.CHj.CHiCH.CHj.COjH and COaH.CHj.CHj.CHiCH.COjH.

Unstable or ASy-acid. Stable or Aa/3-acid.

The unstable variety is formed in the reduction of dichlormuconic acid, or of mu-
conic acid (p. 432), and of diacetylene dicarboxylic acid (p. 432). It dissolves
with difficulty in cold water. It melts at 195°- Potassium permanganate dissolves
it to form malonic acid. If boiled with sodium hydroxide it is transformed into
the stable acid. The latter melts at 169°. Potassium permanganate converts it into
succinic acid. Sodium amalgam reduces the unstable acid, after its conversion
into the stable variety, to adipic acid.

CHj.CCOjH
Dimethyl Fumaric Acid or Maleic Acid || , pyrocinchonic acid,

CHj.CCOjH
is only known in its salts and ethers. When separated from the latter it is at once
transformed into the anhydride, C5H5O3. The latter is obtained by oxidizing
turpentine oil (together with terebic acid), by heating cinchonic acid, CjHjOj,
(with separation of COj), and by heating a-dichlor-, or dibrom- propionic acid,
CH3.CBrj.CO2H, with reduced silver {Berickte, 18, 826, 835). The anhydride
crystallizes from water in large pSarly laminae, which melt at 96° and distil at 223°.
The aqueous solution has a very acid reaction and decomposes alkaline carbonates.
The salts have the formula, CgHgO^Mcj ; its solutions acquire a dark-red color
on the addition of ferric chloride. It is oxidized by a chromic acid mixture, and
yields 2 molecules ofacetic acid and 2 molecules of carbon dioxide. By the action of
sodium amalgam, or by heating with hydriodic acid it is converted into unsymmetri-
cal dimethylsuccinic acid (p. 420) {Berickte, 18, 838). Pyrocinchonic acid, like
malic acid, unites with metallic zinc {Berickte, 18, 844). Consult Berickte, 23,
Ref. 92, upon- metkylitaconic and metkylcitraconic acids.

4. Acids, C,Hi„0, = C5H3(COjH)j.

Allyl Succinic Acid, CgHj.CH./^Q 2j^°2^, results by the withdrawal of

carbon dioxide from allyl ethenyl tricarboxylic acid, C3H5.C2H2(COjH)j (Be-
rickte, 16, 335). It crystallizes firom alcohol in leaflets, melts at 94° and when

* Tetramethylene dicarboxylic acid is isomeric with these unsaturated acids.

DIBASIC ACIDS. 43 1

heated above 140° passes into the corresponding anhydride, C^HgOj — an oil boil-
ing near 250°. Hydrobromic acid converts it into Carbocaprolactonic Acid,
CjHi„04, the lactone of y-oxypropio-succinic acid : —

,CH..CO.H CH..CH.CH,.CH.CH„.CO„H
CH^iCH.CHj.CH/ yields | |

^COjH O CO

The latter melts at 69° and distils at 260° without decomposition.

VCO H
Teraconic Acid, (CH3)2C:CC (-.TT^ r^ri ti, i^ produced in small quantity

(together with pyroterebic acid) (p. 241) in the distillation of terebic acid {Anna-
len, 208, 50), and may be prepared by the action of sodium upon terebic esters
{Annalen, 220, 254). It melts at 162°, decomposing at the same time into water
audits anhydride, CjHgOg. The latter boils near 275° and by its union with
water regenerates teraconic acid. Hydrobromic acid or heat and sulphuric acid
cause it to change to isomeric terebic acid (alactouic acid, see this) {Annalen,22G,
363) :—

(CH3),C:C/ ' yields (C^^3).C.CH ^^.j^a
^ CH,.CO,H 1 '

Teraconic Acid. „.^. . .j

1 erebic Acid.

C2H5.C.CO2H
5. Xeronic Acid, CjHjjOi. or Diethyl Fumaric Acid, ||

C.Hj.C.CO.H
[Berichte, 15, 1321), is very much like dimethyl fumaric acid, and when it is freed
from its salts it immediately decomposes into water and the anhydride, CgHj^Oj.
The latter is produced in the distillation of citraconic anhydride, and is an oil
which is not very soluble in water. It boils at 242°. It volatilizes in a current of
steam. It is also obtained from a-dibrombutyric acid, CjHj.CBrj.COjH, when
heated with silver [Annalen, 239, 276). If it is heated with hydriodic acid it suf-
fers reduction to diethylsuccinic acid (p. 422).

DIBASIC ACIDS, C„H.,„_e04.

CCOjH
Acetylene Dicarboxylic Acid, CJ^fi^ =111 )'s obtained when alco-

C.CO2H
holic potash is allowed to act upon dibrom- and isodibrom-succinic acid (^Berichte,
18, 677; 21, Ref. 658). It crystallizes with two molecules of water, but these
escape on exposure. The anhydrous acid crystallizes from ether in thick plates,
and melts with decomposition at 175°. The acid unites with the haloid acids
to form halogen fumaric acids, C4H3XO4 (p. 427). Its esters unite with bromine
and form dibrommaleic esters. With water they yield oxalacetic acid {Berichte,
22, 2929). The primary potassium salt, C4HKO4, is not very soluble in water
and when heated decomposes into CO2 and potassium propiolate (p. 244).
Traces of acetylene are produced at the same time. Phenylhydrazine converts
acetylene dicarbonic ester directly into the phenylhydrazone of oxalacetic ester
(P- 435)-

432 ORGANIC CHEMISTRY.

C.COj.H
Glutinic Acid, ||| , is obtained by the action of alcoholic potash upon

CCOjH
chlorglutaconic acid (p. 429). It crystallizes from water in minute needles, melt-
ing at 145-146° with evolution of carbon dioxide. This gas is also liberated
when the acid is boiled with water.

CH = CH.CO^H
Muconic Acid, I , is formed when alcoholic potash acts upon

CH = CH.COjH
the dibromide of /3y-hydromuc^nic acid (p. 430). It melts above, 260°. Dichlor-
muconic Acid, CgH^Cl204, results when PCI5 acts upon mucicacid. It yields
/3yhydromuconic acid with sodium amalgam (BerichU, 23, Ref.>232).

Diallyl Malonic Acid, {C^'H.^)^C^^p^„,m obtained from malonic ester.

It melts at 133°- Hyrlrobromic acid converts it into the corresponding dilactone,
which melts at 106° [Annalen, 216, 67), When heated it breaks up into COj and
diallyl acetic acid (p. 245).

Unsaturated Acids : —

(SC.COjH

Diacetylene Dicarboxylic Acid, CjHjO^ = | , is made by the

CsCCO^H
action of potassium ferricyanide upon the copper compound of propiolic acid
[Berichle, 18, 678, 2269). It dissolves quite readily in water, alcohol and ether,
crystallizes in needles or plates with I molecule H^O, instantly assumes a dark
red color on exposure to light, and at 177° explodes with a loud report. Sodium
amalgam reduces it tjo hydromuconic acid, then to adipic acid and at the same
time splits it up into propionic acid. The ethyl ester is an oil boiling at 184°
under a pressure of 200 mm. Zinc and hydrochloric acid decompose it and yield
propargylic ethyl ether, CH=C.CH2.0.C2H5 (p. 136), compare p. 244.

CsC.CsCCOjH

. CO,
C=C.C=C.C02H

escapes on digesting the acid sodium salt of diacetylene dicarboxylic acid with
water, and there is formed the sodium salt of diacetylene monocarboxylic acid,
which cannot be obtained in a free condition. When ferricyanide of potassium
acts upon the copper compound of this acid tetra-acetylene dicarboxylic acid is
formed. This crystallizes from ether in beautiful needles, rapidly darkening on
exposure to light and exploding violently when heated {Berichte, 18, 2271).
Consult Berichte, 18, 2277, for an experiment made to explain the explosibility
of this derivative.

KETONE DICARBOXYLIC ACIDS.

In this class are included the dibasic acids, which contain ketone
groups in addition to the two carboxyl groups. They may be syn-
thesized in the following manner : —

I. By introducing acid radicals into malonic ester. This is done
by acting upon the sodium compounds with acid chlorides : —

CHj.COCl + CHNa(C02.R)2 = CH3.CO.CH(C02R)2 + NaCl.

Aceto-malonic ester.

KETONE DICARBOXYLIC ACIDS.

433

2. By the introduction of acid residues into aceto-acetic ester.
In this case esters of the fatty acids are allowed to act upon the
sodium derivatives (p. 342) : —

CH..C0.CHNa.C02R + Cl.CO„.R = CHj.CO.Ch/^^^^ + NaCl.
Chlorformic Ester. , , .NJT^aK-

Aceto-malonic Ester.

Chloracetic ester, CH2CI.CO2.R, under like conditions, yields
acetosuccinic ester, while ;S-iodo-propionic ester forms acetoglu-
taric ester, etc. Many other dibasic acids are produced in an
analogous manner {Annalen, 216, 39, 127).

The /^ketone dicarboxylic acids, formed as above, sustain the same decomposi-
tions as the /3-ketone monocarboxylic acids (p. 333). Thus, acetosuccinic ester
when acted upon with concentrated potassium hydroxide, breaks down into acetic
and succinic acids (acid decomposition) : —

CH3.CO.CH.CO2R CHj.CO.H

I + 3H2O = CHs.CO.OH + I + 2ROH,

CHj.CO^R CHj.CO^H

Aceto-succinic Ester.

whereas, if boiled with baryta water, or acids, the ketone decomposition occurs,
and the products are CO2, and ;8-acetopropionic acid (Isevulinic acid) : —

CHj.CO.CH.COjR

I + H^O = CH3.CO.CH2.CH2.CO2R + CO2 4- ROH.

CH^.CO^R

Both decompositions occur simultaneously, as in the case of aceto-monocarboxylic
ester.

3. By the condensation of oxalic ester and fatty acid esters
through the action of sodium or sodium alcoholate. This is
analogous to the formation of aldehydic and ketonic esters ( W.
Wislicenus, Berichte, 19, 3325; 20, 3392): —

CO.OR CO.OR

I + CH3.CO2R + Na = I + R.OH.

CO.OR Acetic Ester. CO.CHNa.CO2R

Oxalic Ester. Oxalacetic Ester.

The sodium compounds are first formed. The esters are obtained
by heating them with acids.

The esters of all the fatty acids having primary radicals (carboxyl attached to a
CHj-group, e. g., propionic acid, normal butyric acid), act like the acetic esters.
Isobutyric acid does not react [Berichte, 21, 1156). Propionic ester yields methyl

CO.OR
oxalacetic ester, I , etc.

CO.CH(CH3).C02R

434 ORGANIC CHEMISTRY.

In the same way oxalic and Isevulinic esters yield oxal-laevulinic ester [Beriehte,
22, 885), and oxalic and succinic esters yield oxal-succinic ester — a ketone tricar*
boxylic acid.

I. Mesoxalic Acid, C3H2O5 = COCCO^H).! or C3HA = C
(OH)2.(C02H)2, dioxymalonic acid, is formed from amidomalonic
acid by oxidation with iodine in an aqueous solution of potassium
iodide ; from dibrom-malonic acid by boiling with baryta water or
silver oxide : —

C'^^KSh + ^H.O = C(OH) /^0,H ^ ^HB^.
and by boiling alloxan (mesoxalyl urea) with baryta water.

Preparation. — Add harium alloxanate (5 gr.) to water (l litre) of 80°, then
quickly heat to boiling (5-10 minutes) and filter. As the solution cools, barium
mesoxalate will separate in the form of a fine, crystalline powder. It is decom-
posed with an equivalent quantity of sulphuric acid, the barium sulphate removed
b^. filtration, and the solution concentrated at a temperature of 40-50°, until the
remaining mesoxalic acid solidifies in a crystalline mass.

Mesoxalic acid crystallizes in deliquescent prisms containing i
molecule HjO ; it melts at 115° without loss of water, and at higher
temperatures decomposes into COj and glyoxylic acid, CHO.COjH.
It breaks up into CO and oxalic acid by the evaporation of its
aqueous solution.

As mesoxalic acid contains i molecule of water intimately com-
bined, and as all its salts dried at 110° contain i molecule HjO, it
is considered a dihydroxyl derivative — dioxymalonic acid, C(0H)2.
(C02H)2. Here, as in the case of glyoxylic acid, we observe an
intimate union of two OH groups with i carbon atom, already com-
bined with negative CO2H groups (p. 331). Again, mesoxalic acid
deports itself like a ketonic acid (p. 329), inasmuch as, with a loss
of water, it unites with primary alkaline sulphites, and when acted
upon by sodium amalgam in an aqueous solution of 90°, it is
changed to tartronic acid : —

It combines with hydroxylamine to isonitrosoraalonic acid
(p. 409). With phenylhydrazine it forms the phenylhydrazone,
C(N.NHC8H5)(C02H)2. This is identical with benzene malonic
acid obtained by the action of benzene diazo-salts upon malonic
acid {^Beriehte, 21, 118).

Barium mesoxalate, C(OH)2(^p„2\Ba, and calcium mesoxalate, are crystal-
line powders, not very soluble in water. The ammonium salt, C(,OH)2.(C02.
NH^)^, obtained by evaporating a solution of the acid in ammonium carbonate.

ACETONE DICARBOXYLIC ACID. 435

■ crystallizes in needles. The silver sail, C(OU.) ^.{CO ^Ag) ^, is a white amorphous
powder, which blackens on exposure to the air, and when boiled with water affords
mesoxalic acid, silver oxalate, silver and COj.

The dietkyl ester, C(OH)2(C02.C2H5)2, is obtained by the action of C^HJ
upon the silver salt. It is an unstable oil. It forms a crystalline diamide,
C(OH)2.(CO.NH2)2, with aqueous ammonia. Acetyl chloride converts it into

the diacetyl compound, C{(:>.Q.^\\^0)^(^^-^-i^^^ (p. 196), which crystallizes in
long needles, melting at 145°. X'-Uj.i-atis

CO.CO2H

2. Oxalo-Acetic Acid, C^f>^ ^= I . The diethyl ester (analogous

CH2.CO2H
to acetoacetic ester, p. 431) is formed when sodium acts upon a mixture of oxalic
and acetic esters, and when acetylene dicarboxylic ester is digested with sulphuric
acid. The ester is a thick oil. Heat soon decomposes it. When boiled with
alkalies it breaks down into alcohol, oxalic and acetic acids. Boiling H2SO4
causes it to undergo the ketone decomposition (p. 337) whereby CO, and pyro-
racemic acid (CH3.CO.CO2H) are produced. Ferric chloride imparts a deep red
color to the solution of the ester.

Oxalo-acetic acid is both an a- and /if-ketonic acid (331). The union of the
ester with phenylhydrazine gives rise to a condensation product — a pyrazolon-
derivative {Berichte, 22, 2929). C(N2H.CgH5).C02H

The phenylhydrazine derivativeofamido-oxalo-acetic acid, | ,

CH(NH2).C02H
has been prepared by the reduction of the osazone of dioxytartaric acid [Berithte,
20, 245).

Bromine converts oxalo acetic ester into the dibromide, C4H2Br205. This
undergoes decomposition quite readily [Berichte, 22, 2912).

3. Acids, CgHgOj.

(i) Aceto-malonic Acid, CH3.CO.CH(C02H)2. Its ethyl ester is formed
when chlorcarbonic ester acts upon sodium aceto-acetic ester [Berichte, 22, 2617;
21,3567). It is a mobile liquid, boiling about 240°- It decomposes into CO 2,
acetone and acetic acid when saponified.

2. Acetone Dicarboxylic Acid, CO('^^'-^q'^, may be
obtained by warming citric acid with sulphuric acid : —

CHj. COjH CH2.CO2H

C(0H).C02H = CO + H2O + CO.

CH2.CO2H CH2.CO2H.

Dehydrated citric acid is heated upon a water bath with 2 parts concentrated sul-
phuric acid until the evolution of CO ceases and that of CO2 begins. The rapidly
cooled mass is then mixed with 2^ parts water, when the acid separates as a
crystalline mass. To obtain the diethyl ester the product of the above^^reaction
is at once poured into absolute alcohol (Berichte, 17, 2542; 18, Ref. 468).

Acetone dicarboxylic acid dissolves readily in water and ether;
it crystallizes in colorless needles, melting at 130° when it decom-
poses into CO2 and acetone. The same alteration occurs on boil-
ing the acid with water, acids or alkalies; aceto-acetic ester is also

436 ORGANIC CHEMISTRY.

an intermediate product. The solutions of the acid are colored
violet by ferric chloride. Being a ketonic acid it unites with
phenylhydrazine ; with HCN it yields an oxy-cyanide (p. 202),
which is reconverted into citric acid by hydrochloric acid. The
diethyl ester, 05114(02115)205 (preparation above) is an oily liquid,
which can only be distilled under reduced pressure. The 4H-
atoms of the two OHj-groups in it can be successively replaced by
alkyls {Berichte, 18, 2289).

PCI5 converts the acid into chlorglutaconic acid (p. 429). Ammonia and the
diethyl ester combine to form oxyamidoglutaminic ester {Berichte, 18, 2290),
which condenses further to glutazine (see this) — a trioxypyridine derivative
{Berichte, 19, 2694). The esters of acetone dicarboxylic acid condense with
anilines to form esters of oxyquinoline carboxylic aqids. Phenylhydrazine yields
derivatives of oxy-quinizine (-pyrazole) {Berichte, 18, Ref. 469), Metallic sodium
causes the ester to condense to dioxyphenylaceto-dicarboxylic ester {Berichte, ig,
1446). CO.CO2H

(2) Methyl Oxal-acetic Acid, | , a-oxal- propionic acid.

CH(CH3).C02H
It's ethyl ester is obtained from the esters of oxalic and propionic acids. It is a
colorless oil. Its alcoholic solution is colored an intense red by ferric chloride.
It decomposes into alcohol, oxalic and propionic acids when boiled with alkalies.
By the ketone decomposition (boiling with sulphuric acid) it separates into CO^,
and propionyl carboxylic acid, CHj.CHj.CO.COjH (p. 342) {Berichte, 20, 3394).

4. Acids, CgHjO^.

CH3.CO.CH.CO2H
(i) Aceto-succinic Acid, | . Its ethyl ester is prepared

CHjj.COjH
from aceto-acetic ester and chlor-acetic ester. It boils at 244-250°. Ferric
chloride does not color it. By the acid decomposition it yields acetic and succinic -
acids; by the ketone decomposition the products are COj, and ;8 aceto-propionic
acid (p. 343). The hydrogen atom of the CH-group, in the esters, can be re-
placed by alkyls with the formation of alkyl- aceto-succinic acids (see below).

CO.CO2H
(2) Kthyl Oxal-acetic Acid, | , a-oxal-butyric acid, is ob-

C2H5.CH.CO2H
tained as ethyl ester from oxalic and butyric esters. Isobutyric ester does not
react (p._434)-

5. Acids, CjHigOj. /rH CH CO H

(i) Aceto-glutaricAcid,CH3.CO.CHf ^^2^"2'-'-'2"- its ethyl ester

is formed from aceto-acetic ester, and /3-iodopropionic ester. It yields acetic and
glutaric acids in the acid decomposition.

CH3.CO.C(CH3).C02H

(2) a-Methyl Aceto-succinic Acid, I . Its methyl

CHj.CO^H
ester is formed from methyl aceto-acetic ester and chloracetic ester; also by
methylating aceto-succinic ester. It boils at 263°. The acid decomposition con-
verts it into methyl succinic acid and acetic acid, while by the ketone decompo-
sition (separation of CO»R) the product is /3-aceto-butyric acid (p. 344).

CH3.CO.CH.CO2H

(3) /3-MethyI Aceto-succinic Acid, I , from aceto-

CH(CH,).C02H
acetic ester and a-brom -propionic ester, CH^.CHjBr.COjR, also boils at 263°,

DIACETO-SUCCINIC ACID. 437

and in the acid decomposition breaks down into methyl-succinic acid and acetic
acid. The ketone decomposition yields COjR and /3-aceto-isobutyric acid (p. 344).
(4) Acetone-diacetic Acid, CO<^5^2'CH2.C02n j^^^^ ^^^^^ ^^^ becomes
the 7-dilactone, CyHsO^ :— \^H2.CM.2.t.UjH

CH 2 .0112.0,011 2 -CH 2

I /\ I •

CO O O CO

This is formed when succinic acid is boiled for some time : —

.aC^H^O^ = C,H,0^ + CO2 + 2H,0

(Berichte, 22, 681). It melts at 75°, and distils without decomposition under
reduced pressure. Boiling water, or better, boiling alkalies cause it to become
acetone diacetic acid, by absorption of water. This acid is identical with propion-
dicarboxylic acid, and kydrochelidonic acid. The first is obtained by the action
of HCl upon furfur-acrylic acid, and the latter by the reduction of chelidonic
acid.

Acetone diacetic acid melts at 143°. Acetyl chloride or acetic anhydride will
again convert it into the 7-dilactone. Hydroxylamine changes it to the oxime,
C(N.0H)(C2H^.C02H)2, melting at 129°. Its phenylhydrazone, C(N2H.
C6H5)(C2H4.C02H)2, melts at 107° {Berichte, 22, 68z).

Diketone-dicarboxylic Acids : —

C0.CH,.C0,H

1. Oxal-diacetic Acid, CgHgOj =1 .Its ethyl ester, like

CO.CHj.CO^H
oxal-acetic ester (p. 43S), is produced in the action of sodium upon a mixture of
- oxalic ester with two molecules of acetic ester, (^Berichte, zo, 591) ; also from
oxalic ester and chlor-acetic ester by the action of zinc {Ketipic Acid, Berichte,
20, 202). It consists of leafy crystals, melting at 77°. Ferric chloride imparts
an intense red color to its alcoholic solution. Concentrated hydrochloric acid
sets free the oxaldiacetic acid. This is a white insoluble powder. When heated
it yields, 2 COj, and diacetyl (p. 326). Chlorine and bromine convert the ester
into tetrachlor- and teirabrom-oxaldiacetic ester. The first is called tetrachlordi-
keto-adipic ester, and is also produced when chlorine acts upon dioxyquinone
dicarboxylic ester {Berichte, 20, 3183). ■ CHj.CO.CH^.CH.COjH

2. Oxal-lsevulinic Acid, C-H.Og = \ (?). The

CO.COjH
ethyl ester results from the action of sodium or sodium ethylate upon oxalic and
Isevulinic esters. It is a thick oil. Ferric chloride colors its alcoholic solution
an intense red. Cupric acetate precipitates the copper salt from an alcoholic
solution {Berichte, 21, 2583).

3. Diaceto-succinic Acid, CgHmOj. Iodine converts sod-aceto-acetic
ester (2 molecules) into its ethyl ester {Annalen, 201, 144) : —

CH,.CO.CHNa.CO„R CHj.CO.CH.COjR

+ I. = I + 2NaI.-

CH3.CO.CHNa.CO2R CH3.CO.CH.CO2R

It crystallizes in thin plates and melts at 78°. It is very unstable. It undergoes
various re-arrangements, in accord with its y-diketonic nature (with the atomic
group — CO.CH.CH.CO — ). Thus, when heated or when acted upon by acids.

438 ORGANIC CHEMISTRY.

it yields carbopyrotritartaric ester (a derivative of furfurol). Pyrrol derivatives
result when it is acted upon with ammonia and amines. This reaction will serve
for the detection of diaceto-succinic ester {Berichte, ig, 14). Phenylhydrazone
produces dipyrazolbn derivatives [Annalen, 238, 168).

Sodium hydroxide causes the ester to break down into aCOj, and acetonyl
acetone (p. 328).

Iodine, acting upon disod-diaceto-succinic ester, produces diaceto-fumaric ester,
CHs.CO.C.COjR

II ■ , melting at 96°.

CH,.CO.C.CO,R

Analogues of Diacetosuccinic Acid : —

CH2.CH(CO.CH3).C02H

Diaceto-adipic Acid, | . Ethylene bromide acting

CH2.CH(CO.CH3).C02H

upon two molecules of sodacetoacetic ester, forms its diethyl ester [Berichte, 19,

2045). Phenylhydrazine converts it" into a dipyrazolon-derivative [Berichte, 19,

2045). CH3.CO.CH.CO2H

Diaceto-glutaric Acid, | . Its ester is obtained from

CHj.CO.CH.CHjjCOaH
aceto-acetic ester and from Isevulinic ester (p. 343). Being a y-diketone com-
pound it unites with ammonia and forms a pyrrol-derivative [Berichte, 19, 47).

CO.CH.COjH
Oxal-succinic Acid, C5H5O- ^ | \ , is an analogous ketone

COjHCH^.COjH
tricarboxylic acid. Its ethyl ester forms when sodium ethylate acts upon oxalic
ester and succinic ester. When its dilute solutions are digested, oxalic and
Isevulinic acids are produced. Being a j8-ketonic acid derivative, its ester yields
a pyrazolon compound with phenylhydrazine [Berichte, 22, 885).

When metallic sodium is permitted to act upon a mixture of oxalic ester, with
two molecules of acetic ester, the product will be —
CO.CH2.CO2.C2H5
Oxalyl-diacetic Ester, I = Ci^Hi^Oj. Thisisaleafy

CO.CH2.COj.C2H5
crystalline mass, melting at 76-77°. Its alcoholic solution becomes an intense
red upon the addition of ferric chloride [Berichte, 20, 591). This ester is also
called ketipic ester and results in the action of zinc upon a mixture of oxalic ester
and chloracetic ester [Bfrichte, 20, 202).

CARBAMIDES OF THE DICARBOXYLIC ACIDS.

The urea derivatives or carbamides (ureides) of these acids are
perfectly analogous to those of the dihydric acids (p. 399). By the
replacement of two hydrogen atoms in urea we obtain the true
ureides. The alkalies convert these then into acids of the uric acid
group:—

.NH.CO .NH.CO.CO.OH

C0( I +H,0 = CO(

^NH.CO ^NHj

Oxalyl Urea. Oxaluric Acid.

CARBAMIDES OF THE DICARBOXYLIC ACIDS. 439

The latter decompose further into urea (also COj and NHj) and
acid, whereas the ureides of the divalent acids yield amido-acids.
Most of the carbamides were first obtained as decomposition pro-
ducts of uric acid. .NH.CO

Oxalyl Urea, C3H2N,03 = CO( | , Parabanic Acid,

/^ NH.CO
is produced in the energetic oxidation of liric acid and alloxan (p.
443), and is obtained by evaporating a solution of uric acid in
three parts of ordinary nitric acid {Annalen, r'jT., 74). It is syn-
thetically prepared by the action of POCls upon a mixture of urea
and oxalic acid. It is soluble in water and alcohol, but not in ether,
and crj^tallizes in needles or prisms. Under peculiar conditions
it crystallizes with one molecule of water, which it does not lose
until heated to 150°. Oxalyl urea reacts acid, possesses an acid
character, as it contains two imide groups (p. 412) linked to car-
bonyls, and is ordinarily termed parabanic acid.

Its salts are unstable; water converts them at once into oxalurates. The primary
alkali salts, e. g., CjHKNjOj, are obtained as crystalline precipitates by the addi-
tion, of potassium or sodium ethylate to an alcoholic solution of parabanic acid.
Silver nitrate precipitates the crystalline disilver salt, CjAgjNjOj, from solutions of
the acid.

Methyl Parabanic Acid, C3H(CH3)Nj03, is formed by boiling methyl uric
acid, or methyl alloxan, with nitric acid, or by treating theobromine vfith a chromic
acid mixture. It is soluble in ether and crystallizes in prisms, which melt at 149.5°-
Alkalies convert it into methyl urea and oxalic acid.

Dimethyl Parabanic Acid, C3(CH3)jNj03, Cholestrophane, is obtained
from thelne by boiling with nitric acid, chlorine water or chromic acid, or by
heating methyl iodide with silver parabanate, C3Ag2N205. It crystallizes in pearly
laminas, melts at 145°, and distils at 276°. Allcalies decompose it into oxalic acid
and dimethyl urea; the latter even yields CO2 and two molecules of CH3.NH2.

Oxaluric Acid, C3H,N.04 = C0(^J5J^-^°-^°^". Its salts

are formed by the action of bases on parabanic acid. They are not
readily soluble in water, and usually separate in crystalline form.
The ammonium salt, C3H3(NH4)N204, and the silver salt, C^^k.^^
Oi, crystallize in glistening needles. Free oxaluric acid is liberated
by mineral acids from its salts as a crystalline powder, dissolving
with difficulty. When boiled with alkalies or water it decomposes
into urea and oxalic acid ; heated to 200° with POCI3 it is again
changed into parabanic acid.

The ethyl ester, C^Yi^[C^Yi-^)'Vi fi ^, is formed by the action of ethyl iodide on
the silver salt, and has been synthetically prepared by letting ethyl oxalyl chloride
act upon urea :—

,NH, GOCl NH.CO.CO2.C2H5

Co/ -f I = CO( + HCl.

\nH2 CO2.C2H5 ^NH^

44° ORGANIC CHEMISTRY.

It crystallizes from warm water in thin, shining needles, which melt with decom-
position at 177°. Ammonia and silver nitrate added to the solution of the ether
precipitate silver parabanate.

Oxaluramide, C3H5N3O3 = C0<;^^g-'^°-'-'°-^^2, Oxalan, is produced on

heating ethyl oxalurate with ammonia, and by fusing urea with ethyl oxamate,

Q,0{ ^,^ '^r \^ • It is a crystalline precipitate, dissolving with difficulty in water,

and decomposing when boiled with water into urea, ammonia and oxalic acid.

-NH.CH.OH
= CO^ I , AUanturic Acid, is the

^NH.CO

urelde of glyoxalicacid, CHfOHjj.COjH, and is obtained from allantoiin on warm-
ing with baryta water or with PbOj, and by the oxidation of glycolyl urea (hydan-
toin, p. 391). It is a deliquescent, amorphous mass, insoluble in alcohol; it forms
salts with one equivalent of base. When the potassium salt is boiled with water it
decomposes into urea and glyoxalic acid, which is further transposed into glycoUic
and oxalic acids (see p. 330).

Allantoiin, C^HgN^Oj, is a di-urelde of glyoxalic acid. It is present in the
urine of sucking calves, in the allantoic liquid of cows, and in human urine after
tlie ingestion of tannic acid. It is produced artificially on heating glyoxalic acid
(also mesoxalic acid CO(C02H)2) with urea to 100° : —

.NH^ CHO /NH.CH.NH ,

2C0( + I =C0<; I )C0 + 2H2O.

^NHj CO.OH ^NH.CO.NH^ ^

Pyruvil (CjHjNiOj) is formed in a similar manner from urea and pyroracemic
acid.

AUantoin is formed by oxidizing uric acid with PbOjjMnOj, potassium ferri-
cyanide, or with allcaline KMnO^ [Berichie, 7, 227) ; —

C,H^N^03 + O + H^O = C^HeN^O, + CO^.

AUantoin crystallizes in glistening prisms, which are slightly soluble in cold
water, but readily in hot water and in alcohol. It has a neutral reaction, but dis-
solves in alkalies, forming salts. Ammoniacal silver nitrate precipitates the com-
pound, CjHjAgN^Oj — a white powder. When boiled with baryta water it decom-
poses into COj, NH3, oxalic acid and glycolyl urea (hydantoin).

Sodium amalgam' converts allantoin into glyco-uril, C^HgN^^Og, which is
identical with acetylene urea (^Berichie, ig, 2479) '■ —

,NH2- CHO /NH.CH.NH.

2C0( + I = CO( I >C0 + 2H2O.

^NHj CHO ^NH.CH.NH/

It crystallizes in long needles or prisms. It breaks down into hydantoic acid (p.
392) and urea when boiled with baryta water.

NITROBARBITURIC ACID. 441

Malonyl Urea, C^H^NaO, = CO<^^y-^Q\CH„ Barbituric

Acid, the ureide of malonic acid, is obtained from alloxantin (p.
444) by heating it with concentrated sulphuric acid, and from di-
brombarbituric acid by the action of sodium amalgam. It may also
be synthetically obtained by heating malonic acid and urea to ioo°
with POCI3. It crystallizes with two molecules of water in large
prisms from a hot solution, and when boiled with alkalies is decom-
posed into malonic acid and urea.

The hydrogen of CHj in malonyl urea can be readily replaced
by bromine, NO2 and the isonitroso-group. The metals in its salts
are joined to carbon and may be replaced by alkyls (^Berichte, 14,
1643 ; 15. 2846).

When silver nitrate is added to an ammoniacal solution of barbituric acid, a
white silver salt, C^H^AgjNjOj, is precipitated. Methyl iodide converts this

into Dimethylbarbituric Acid, CO;f NH TO / *-'(^^3)2- ''^^''^ forms shining

laminae, does not melt at 200°, and sublimes readily. Boiling alkalies decompose
it into CO2, NH3, and dimethyl malonic acid. Its isomeride, /3-Dimethyl Bar-
bituric Acid, C0(^ iyT/pTT'<'pQ yCHj, is produced from malonic acid and

dimethyl urea through the agency of POCI3. It melts at 123°.

Bromine converts barbituric acid, nitro-, isonitroso-, and amido-barbituric acids

into Dibrombarbituric Acid, C^^HjEr^NjOj = CO^ jttt'pq ^CBrj. This

dissolves readily in hot water, in alcohol and in ether. It crystalliEes in laminae
or prisms. Boiling water converts it into mesoxalyl-urea (alloxan).' Nascent
hydrogen or hydriodic acid causes it to revert to barbituric acid, and hydrogen
sulphide transforms it into tartronyl-urea (dialuric acid).

Nitrobarbituric Acid, C4H3(N02)N203, Dilituric Acid, is obtained by the
action of fuming nitric acid upon barbituric acid and by the oxidation of violuric
acid [Berichte, 16, 1135). It crystallizes with three molecules of water in color-
less laminae or prisms, which impart a yellow color to water. It can exchange
3 hydrogen atoms for metals. Its salts are principally those haying but one equiva-
lent of metal. They are very stable and, as a general thing, are not decomposed
by mineral acids.

Isonitroso-barbituric Acid, C4H2(N.OH)N203, Violuric Acid, is obtained
by acting with potassium nitrite upon barbituric acid. Barium chloride precipi-
tates a red colored salt from the solution ; this is decomposed by sulphuric acid.
Furthermore, it is prepared (according to the usual methods of forming isonitroso-
compounds, p. 214) by the action of hydroxylamine upon alloxan. It crystallizes
in yellow, rhombic octahedra with i molecule of water. It gives blue, violet and
yellow colored salts with one equivalent of metal. The potassium salt, C^H^K
(N0)N20, -j- 2H2O, crystallizes in dark blue prisms and dissolves in water with
a violet color. Ferric acetate imparts a dark blue color to the solution. When
heated with alkalies violuric acid breaks up into urea and isonitroso malonic acid
(p. 409).

Amido-barbituric Acid, C4H3(NH2)N203 (Uramil, Dialuramide, Murexan),
is obtained in the reduction of nitro- and isonitroso-barbituric acid with hydriodic

37

442 ORGANIC CHEMISTRY.

acid ; by boiling thionuric acid with water, and by boiling alloxantin witli an
ammonium chloride solution : —

CjH^N^O, + NHj.HCI = C^H (NH,)N203 + C^H.N^O^ + HCl.
Alloxantin. Uramil. Alloxan.

Alloxan remains in solution, while uramil crystallizes out. It is only slightly soluble
in water, and crystallizes in colorless, shining needles, which redden on exposure.
Murexide (p. 445) is produced when the solutionis boiled with ammonia. Nitrous
acid converts uramil into alloxan : —

C0<SS:^8>CH.NH, yields Co(Ng;CO\o.

Thionuric Acid, C4H5N3SO5 = CO/^ jttt'qq /C(^c,„ ?,,sulphamidobar-

bituric acid, is obtained by heating isonitrosobarbituric acid or alloxan with ammo-
nium sulphite. Its ammonium salt, C^H^[T^'il^'!fi^50^ -f- HjO, is made by
boiling alloxan with sulphurous acid and ammonia. It forms bright scales.. Free
thionuric acid is obtained by acting on the lead salt with hydrogen sulphide. It is
a readily soluble crystalline mass. It reduces ammoniacal silver solutions, and
when boiled with water breaks up into sulphuric acid and uramil.

Uracyl, C^H^NjOj ^= C^OCjjh CO /^^' '^^ ureide of j8-oxyacrylic acid,

CH(OH):CH COjH, is only known in its derivatives.

Methyl Uracyl, C4H3(CH3)N202 = Cq/^^-^^^^s) Vh. Thisispro-

duced when urea acts upon aceto-acetic ester, which reacts in the tautomeric form
of ;8-oxycrotonic ester {^Annaien, 229, l) : —

NH, CH(CH3) NH.C(CH3)\
C0( + II = C0( I CH + R.OH + H.O.

^NHa C(OH).CO.OR ^NH.CO /

Concentrated nitric acid converts it into Nitrouracyl-carboxylic Acid,

CO(^-^Trj'pn ^ '' /C.NO3. This passes, by elimination of CO.H, and reducr

\i>iri.i.^u / /NH CH==i^

tion of its nitro-group, mto amidouracyl, COf ivTH-'r-n ^~^CMl^„,&nAoxyura-

/NH CH ==:;--. \iNrl,t.U /

cyl, CO;' -|.TTT'r.n ^~~;C.OH, isobar bituric acid. Bromine water converts the

latter into isodialuric acid, Q0{ jjij rn ^C.OH. This yields uric acid when

heated with urea and sulphuric acid (p. 445) [Benckte,zi, 999; Annalen, 251,

235)-

Tartronyl Urea, QH^N^Oj, = CO/^][][-^q^CH.OH, dialu-

ric acid, the ureide of tartronic acid, CH(OH)(C02H)2, is formed
by the reduction of mesoxalyl urea (alloxan) with zinc and hydro-
chloric acid, and from dibrombarbituric acid by the action of hydro-
gen sulphide. On adding hydrocyanic acid andjpotassium car-

MESOXALYL UREA. 443

bonate to an aqueous solution of alloxan, potassium dialurate separates
but potassium oxalurate remains dissolved : —

2C^H,N,0^ + 2KOH = C^H,KN,0^ + CjH.KN.O^ + CO,.

Potassium Dialurate, Potassium Oxalurate.

Dialuric acid crystallizes in needles or prisms, has a very acid
reaction and forms salts with i and 2 equivalents of the metals. It
becomes red in color in the air, absorbs oxygen and passes over into
alloxantin, zQH^N.O^ + O = CsH^NiO, + 2H2O.

MesoxalylUrea,QH,N204=CO(^^![][-^Q^CO, Alloxan,

the ureide of mesoxalic acid, is produced by the careful oxidation
of uric acid, or alloxantin with nitric acid or chlorine and bromine.

Preparation. — Add uric acid gradually to cold nitric acid of specific gravity
1.4, as long as a reaction occurs. Then let the whole stand for some time. The
separated, crystalline mass of alloxan is drained upon an asbestos filter, warmed
upon a water bath to expel all nitric acid, and then recrystallized from water ;
alloxantin remains in the mother-liquor.

Moisten alloxantin with concentrated nitric acid (sp. gr. 1.46), let stand until it
has been completely changed to alloxan (a small portion should dissolve readily
in cold water), and then purify the latter as already described.

Alloxan crystallizes from warm water in long, shining, rhombic
prisms, with 4 molecules of H^O. When exposed to the air they
effloresce with separation of 3H2O. The last molecule of water is
intimately combined (p. 434), as in mesoxalic acid, and does not
escape until heated to 150°. Small stable crystals, with i H2O
separate out from hot solutions. Alloxan is easily soluble in water,
has a very acid reaction and possesses a disagreeable taste. The
solution placed on the skin slowly stains it a purple red. Ferrous
salts impart a deep indigo blue color to the solution. When hydro-
cyanic acid and ammonia are added to the aqueous solution the
alloxan decomposes into COj, dialuric acid and oxaluraraide (p. 440),
which separates as a white precipitate (reaction for detection of
alloxan).

The primary alkali sulphites unite with alloxan just as they do with mesoxalic
acid, and we can obtain crystalline compounds, r.g., CiHjN^O^.SOjKH + HjO.
Pure alloxan can be preserved without undergoing decomposition, but in the
presence of even minute quantities of nitric acid it . is converted into alloxantin.
Alkalies, lime or baryta water, change it to alloxanic acid, even when acting in the
cold. Its aqueous solution undergoes a gradual decomposition (more rapid on
heating) into alloxantin, parabanic acid and COj : —

■^ * " ' Alloxantin. Oxalyl Urea.

444 ORGANIC CHEMISTRY.

Boiling dilute nitric aeid oxidizes alloxan to parabanic acid (oxalyl urea) and
CO^:—

.NH.CO. .NH.CO

co(f )co + o = cor I + cOj.

^nh.cq/ ^NH.CO

Mesoxalyl Urea. Oxalyl Urea.

The mesoxalic acid residue, like the free acid (p. 434), splits off a CO-group,
readily forming oxalyl.

Reducing agents, like hydriodic acid, change alloxan, in the cold, to alloxantin,
on warming, however, into tartronyl urea (dialuric acid).

Methyl Alloxan, C4H(CHg)N204, is produced by the oxidation of methyl uric
acid. Alkalies convert it at once into methyl alloxanic acid. Nitric acid changes
it to methyl parabanic acid (p. 439).

Dimethyl Alloxan, CO(N.CH3)jC303, is produced when aqueous chlorine
(hydrochloric acid and KCIO3) acts on theine, and by the careful oxidation of
tetramethyl alloxantin with nitric acid. When the solution is concentrated, dime-
thyl alloxan remains as a non-crystallizable syrup. It gives all the reactions of
alloxan. HjS reduces it to tetramethyl alloxantin (see below). By energetic
oxidation, it yields dimethyl oxalyl urea (p. 405).

Alloxanic Acid, C^H^NjOj = co/^g^*-'-^°-^°''-'^. When the alkalies

act on alloxan the latter absorbs water and passes into the acid. If baryta water
be added to a warm solution of alloxan, as long as the precipitate which forms con-
tinues to dissolve, barium alloxanate, C^^ri2^^LNfi^ -|- 4H2O, will separate out in
needles when the solution cools. To obtain the free acid, decompose the barium
salt with sulphuric acid and evaporate at a temperature of 30-40°. A mass of
crystals is obtained by this means. Water dissolves them easily. Alloxanic acid
shows a very acid reaction, dissolves zinc, and is indeed a dibasic acid, inasmuch
as both the hydrogen of carboxyl and of the imide group can be exchanged for
metals. When the salts are boiled with water, they decompose into urea and
mesoxalates.

By the union of two molecules of the ureides of the dicarboxylic acids we get
the compounds oxalantin, alloxantin, and hydurilic and purpuric acids. These are
termed di-ureides.

Oxalantin, CjHjN^Oj, Leucoturic Acid, is obtained by the action of zinc
and hydrochloric acid upon oxalyl urea: — aCjHjNjOj + Hj ^ CgHjN^Og.
HjS separates it from the zinc salt. It forms crystalline crusts which dissolve with
difficulty in water, and it also reduces ammoniacal solutions of both silver and
mercury.

Alloxantin, CjH^N^^O,, is obtained by reducing alloxan with SnClj, zinc and"
hydrochloric acid, or H^S in the cold: aC^H^NjO^ + H, = CgH^NiO, +
H^O ; or by mixing solutions of alloxan and dialuric acid : C,H2N204 + CjH^N204
=: CjH^N^O, + HjO. Most readily prepared by warming uric acid with dilute
nitric acid [Annalen, 147, 367). It crystallizes from hot HjO in small, hard
prisms with 3HjO and turns red in air containing ammonia. Its solution has an
acid reaction ; ferric chloride and ammonia give it a deep blue color, and baryta
water produces a violet precipitate, which on boiling is converted into a mixture
of barium alloxanate and dialurate.

Tetramethyl Alloxantin, C8(CH3)4N40, = 01^11^ ^'i'i^O.,, Amalic Acid,
is formed by the action of nitric acid or chlorine water upon theine, or better, by

URIC ACID. 445

the reduction of dimethyl alloxan (see above) with hydrogen sulphide [Anna/en,
215, 258) :—

2C,(CH3),N,0, + H, = Ce(CH3),N,0, + H,0.

It consists of colorless, sparingly soluble crystals, which impart a red color to the
skin; alkalies and baryta water give it a violet-blue color. When carefully
oxidized by nitric acid, or by the action of chlorine [Annalen, 221, 339) it is again
altered to dimethyl alloxan ; more energetic reaction produces dimethyl parabanic
acid.

Hydurilic Acid, CgHgN^Og. The ammonium salt is formed on boiling
alloxantin with dilute sulphuric acid; by heating dialuric acid with glycerol to
150°; and also on heating aqueous alloxan or alloxantin to 170°. The free acid
is obtained by decomposing the copper salt with hydrochloric acid. It crystallizes
from hot water in little prisms having 2H2O, and is a dibasic acid. Ferric chlor-
ide imparts a dark green color to the solution of the acid or its salts. Ordinary
nitric acid decomposes hydurilic acid into nitro- and nitroso-barbituric acid ; fuming
nitric acid forms alloxan.

Purpuric Acid, CjHjNjO^, is not known in the free state, because as soon
as it is liberated from its salts by mineral acids it immediately decomposes into
alloxan and uramil. The ammonium salt, C5H^(NH^)N508 -f- HjO, is the
dye-stuff murexide. This is formed by heating alloxantin to 100° in ammonia
gas ; by mixing ammoniacal solutions of alloxan and uramil : —

C.H^N^O, .+ C,H,N303 -f NH3 = C3H,(NHJN,0e -f H3O;

and by evaporating uric acid with dilute nitric acid and pouring ammonia over
the residue (murexide reaction). It is most readily obtained from uramil (p. 441).
Dissolve 4 parts of the latter in dilute ammonium hydroxide, add 3 parts of mer-
curic oxide and heat to boiling, when mercury will separate and the solution
assume a dark-red color : —

2C,H,N303 + O = C3H,(NHJN30, -f H,0.

Murexide separates from the solution on cooling. It forms four-sided plates or
prisms with one molecule of HjO, and has a gold-green color. It dissolves in
water with a purple-red color, but is insoluble in alcohol and ether. It dissolves
with a dark blue color in potash ; on boiling NH3 is disengaged and the solution
decolorized.

Uric Acid, C5H4N4O3, occurs in the juice of the muscles, in the
blood and in the urine, especially of the carnivorse, the herbivorse
separating hippuric acid; also, in the excrements of birds, reptiles
and insects. When urine is exposed for awhile to the air, uric acid
separates ; this also occurs in the organism (formation of gravel and
joint concretions) in certain abnormal conditions.

Uric acid is prepared artificially by heating glycocoU with urea
(10 parts) to 200-230° {Berichte, 17, 443.)) Pr trichlorlactamide
with urea {Berichte, 20, Ref. 472). It may be directly synthesized
by heating isodialuric acid (p. 442) and urea with sulphuric acid (p.
446) (Behrend, Berichte, 22, Ref. 397).

446 ORGANIC CHEMISTRY.

Uric acid is best prepared from guano and the excrements of reptiles. Guano is
boiled with a hot borax solution (i part borax in 120 parts H^O) and the uric
acid precipitated from the filtrate by hydrochloric acid. Or, after removing the
phosphates from guano by means of dilute hydrochloric acid, it is dissolved in
concentrated sulphuric acid (in equal weight), and the uric acid precipitated by
pouring the solution into water (12-15 'vols). To obtain the acid pure, it is dis-
solved in caustic potash and carbon dioxide conducted into the liquid, when potas-
sium urate will be precipitated ; hydrochloric acid sets free the uric acid.

The excrements of reptiles (ammonium urate) are boiled with dilute potassium
or sodium hydroxide until the odor of ammonia is no longer perceptible, the hot
solution filtered and the filtrate poured into dilute hydrochloric acid.

Uric acid is precipitated as a shining, white powder, from solu-
tions of its salts. It is odorless and tasteless, insoluble in alcohol
and ether, and dissolves with difficulty in water; i part requires
15,000 parts water of 20° for its solution, and 1800 parts at 100°.
Its solubility is increased by the presence of salts like sodium phos-
phate and borate. Water precipitates it from its solution in con-
centrated sulphuric acid. On evaporating uric acid to dryness with
nitric acid, we obtain a yellow residue, which assumes a purple-red
color if moistened with ammonia, or violet with caustic potash or
soda (murexide reaction, p. 445). Heat decomposes uric acid into
NH3, CO2, urea and cyanuric acid.

Uric acid acts like a weak dibasic acid, forming chiefly, how-
ever, salts containing but one equivalent of metal. The secondary
alkali salts are obtained by dissolving the primary salts or the free
acid in the hydroxides of potassium and sodium ; they show a very
alkaline reaction, and are changed to the primary form by CO, and
water. When CO2 is conducted through the alkaline solution, the
primary salts are precipitated. Uric acid forms primary salts with
the alkaline carbonates.

The dipotassium salt, CjHjKjNjOj, separates in needles when its solution is
evaporated. It dissolves easily in potash and in 40 parts of water at ordinary tem-
peratures. The primary salt, CjHjKNjOj, is precipitated from solutions of the
dipotassium salt as a jelly, which soon becomes granular and dissolves in 800 parts
of water at 20°. The primary sodium salt is more insoluble. The primary am-
monium salt, CjH3(NHj)N403, is precipitated as a sparingly soluble powder, by
ammonium chloride, from the solutions of the other salts.

Methyl Uric Acid, C5H3(CH3)N403, is obtained by heating primary lead
urate with methyl iodide and ether to 160°. It consists of small needles, which
are rather insoluble in water. When heated with concentrated hydrochloric acid
to 170° it decomposes into NHj, COj, methylamine and glycocoU [Berichte, 17,
330) •

Dimethyl Uric Acid, C5Hj(CH3)jN^03, obtained from the secondary lead
salt, crystallizes with one "molecule of water, which is not expelled until heated to
160°. It yields the same decomposition products as the preceding (2 molecules
methylamine). Both acids are capable of forming primary and secondary salts,
which are perfectly analogous to those of uric acid.

URIC ACID. 447

Careful oxidation converts dimethyl uric acid (analogous to uric acid) into
methyl alloxan and methyl urea.

Consult Berichte, 17, 1777, for an isomeric /3-methyl- and /?-dimetliyl uric acid.

When uric acid is carefully oxidized, either with cold nitric acid
or with potassium chlorate and hydrochloric acid, it yields mesoxalyl
urea and urea: —

C,H,NA + O + H,0 = C0/^H-C0\ CO ^ H,N/^°-

Its structure is probably represented by the formula : —

NH— C— NH.
/ II )co,

CO C— NH^

\ I

NH— CO

which was first proposed by Medicus. This would make it the di-
ureide of acrylic acid, or more correctly, that of the hypothetical
compound, CO = C(0H)—C02H (^mV/^/^, 17, 1776). This is
demonstrated by its synthesis from urea and the amide of trichlor-
lactic acid (p. 445), and more directly by its synthesis from iso-
dialuric acid and urea : —

NH— C(OH) HjN. /NH— C— NH.

/ II + )CO=CO II )C0

CO C(OH) H.N/ \ C— NH ^ + H^O.

\ I • \ 1

NH— CO NH— CO

Isodialuric Acid. , Uric Acid.

The presence of four imide groups explains how it and also di-
methyl uric acid are capable of forming salt-like compounds with
I and 2 equivalents of the metals.

Guanine, xanthine, hypoxanthine, and carnine stand in close
relation to uric acid. Like it they occur as products of the meta-
bolism of the animal organism. Xanthine and hypoxanthine occur
in the extract of tea. Theobromine and caffeine found in the
vegetable kingdom are very similar to them ; these are also in-
cluded among the alkaloids because of their basic character. An
approximate representation of the constitution of xanthine, theo-
bromine and caffeine is given in the following formulas : —

H— N C=N CH3.N C=N CH3.N C=N

I I \ro I I "^CO I I \co

CO C— NH/^" CO C-N/^^ CO C— N/^^ .

I II I II \CH I II \CH

H— N CH H— N C "-"sCHj-N C '^"^

Xanthine. ' Theobromine. Caffeine.

448 ORGANIC CHEMISTRY.

They would accordingly be the di-ureides of an acid with three
carbon atoms (as mesoxalic acid). Theobromine is dimethyl- and
caffeine trimethyl-xanthine. They may be artificially prepared by
introducing methyl into xanthine. The decomposition of caffeine
(by action of chlorine) into dimethyl oxalyl-urea (dimethyl alloxan,
p. 444) and methyl urea (also Annalen, 221, 313) is especially sug-
gestive in explaining the constitution : —

Caffeine. Dimethyl Alloxan. Methyl Urea.

Nitrous acid converts guanine into xanthine, and in its decomposition yields

guanidine, ^t^ \(;;__ NH; hence we can consider it as xanthine, in which a

guanidine residue occurs instead of that of urea, i. e., the oxygen of a CO-group
has been replaced by imide, NH.

Sodium amalgam converts uric acid into xanthine and sarcine, hence all these
compounds are intimately related to uric acid, which fact is manifest in their
analogous formulas.

Guanine, C5H5N5O, occurs in the pancreas of some animals and
very abundantly in guano.

To obtain it, guano is boiled several times with milk of lime until the liquid no
longer shows a brown color; in this manner coloring substances and certain acids
are removed ; uric acid and guanine constitute the chief portion of the residue. The
latter is boiled with soda, filtered, sodium acetate added, and the whole strongly
acidulated with hydrochloric acid, which causes the precipitation of guanine,
accompanied by some uric acid. The precipitate is dissolved in boiling hydro-
chloric acid and the guanine thrown down by ammonium hydroxide.

Guanine is an amorphous powder, insoluble in water, alcohol and
ether. It yields crystalline salts with i and 2 equivalents of acid,
e.g., C5H5N5O.2HCI. It also forms crystalline compounds with
bases. Silver nitrate gives a crystalline precipitate, CsHjNsO.
NOaAg.

Nitrous acid converts guanine into xanthine. Potassium chlorate
and hydrochloric acid decompose it into parabanic acid, guanidine
and COj (see above).

Xanthine, CjH^N^Oj, occurs in slight amounts in many animal secretions, in
the blood, in urine, in the liver, in some forms of calculi and in tea extract. It
results from the action of nitrous acid upon guanine {^Annalen, 215, 309). It is a
white, amorphous mass, somewhat soluble in boiling water, and combines with
both acids and bases. It is readily soluble in boiling ammonia; silver nitrate pre-
cipitates C5H2.Ag2N402 -f H2O from its solution. The corresponding lead com-
pound yields theobromine (dimethyl xanthine) when heated to 100° with methyl
iodide. When xanthine (analogous to caffeine, page 449) is warmed with potas-
sium chlorate and hydrochloric acid it splits into alloxan and urea.

THEOBROMINE — CAFFEINE. 449

Sarcine, CjH^N^O, Hypoxanthine, is a constant attendant of xanthine in the
animal organism, and is distinguished principally by the difficult solubility of its
hydrochloride. It consists of needles not very soluble in water, but dissolved by
alkalies and acids. Silver nitrate precipitates the compound CjHjAgjN^^O -j-
HjO from ammoniacal solutions.

Adenine, C5H5N5, has been isolated from beef pancreas. It also occurs in
tea extract. It crystallizes in leaflets with pearly lustre. It has three molecules
of water of crystallization. At 54° the salt becomes white in color, owing to loss
of water. Nitroiis acid converts it into hypoxanthine. It is, therefore, an amide,
C5H3(NHj)Ni, or imide, CjH^CNHjN^, (Berichte, 23, 225).

Carnine, CjHgNiO + H2O, has been found in the extract of beef. It is a
powder, rather easily soluble in water, and forms a crystalline compound with
hydrochloric acid. Bromine water or nitric acid converts carnine into sarcine.

Theobromine, C,H8N402 = C5H.,(CH3)jN402, dimethyl xan-
thine, occurs in cocoa-beans (from Theobroma Cacao) and is pre-
pared by introducing methyl into xanthine (see above).

Divided cocoa-beans are boiled with water, tannic acid and other substances
precipitated by basic lead acetate, and hydrogen sulphide conducted into the fil-
trate to remove excess of lead. The solution is then evaporated to dryness and
the theobromine extracted firom the residue with alcohol.

Theobromine is a crystalline powder with a bitter taste and dis-
solves with difficulty in hot water and alcohol, but rather easily in
ammonium hydroxide. It sublimes (about 290°) without decompo-
sition, when it is carefully heated. It has a neutral reaction, but
yields crystalline salts on dissolving in acids ; much water will de-
compose these. Silver nitrate precipitates the compound, C,H,Ag
NiOz, in crystalline form from the ammoniacal solution after pro-
tracted heating. When this salt is heated with methyl iodide it
yields methyl theobromine, C,H,(CH3)N402, i. e., caffeine.

Theophylline, C^HgN^Oj = C5Hj(CH,)2N402, is isomeric with thepbro-
mine. It is present in tea extract. It contains one molecule of water of crystal,
lization, which it loses at 110°. The introduction of methyl converts it into
theine. [^Berichte, 21, 2164).

Caffeine, Theine, CsHuNA, methyl theobromine, trimethyl
xanthine (p. 447), occurs in the leaves and beans of the coffee tree
(i^ per cent.), in tea (2-4 per cent.), in Paraguay tea (from Ilex
Paraguay ensis), and in guarana (about 5 per cent.) the roasted pulp
*of the fruit of Paullinia sorbilis. The caffeine is procured from
these sources, just as theobromine is obtained. It is also found in
minute quantities in cocoa.

Caffeine consists of long, silky needles with i molecule of water ;
they are only slightly soluble in cold water, and alcohol. At 100°
it loses its water, melts at 225° and sublimes at higher temperatures.

It has a feeble bitter taste and forms salts with the strong min-
eral acids; water readily decomposes them. On evaporating a
38

45° ORGANIC CHEMISTRY.

solution of chlorine water containing traces of caffeine we get a
reddish-brown spot, which acquires a beautiful violet-red color
when dissolved in ammonia water.

Sodium hydroxide converts theine into caffeidine carboxylie acid, C,HjjN40.
CO2H, which readily decomposes into CO^ and caffeidine, Q,^Yi.^^^O {Berichte,
16, 2309). The latter is also obtained when caffeine is boiled with baryta water;
it is a readily soluble, strong base and decomposes on protracted boiling into NHj,
methylamine, formic acid and methyl glycocoll. For other caffeine derivatives (apo-
caffeine, caffuric acid, caffolin) see Annalen, 215, 261, and 228, 141.

Chlorine water breaks caffeine up into dimethyl alloxan and methylurea (p. 448).
By energetic action of chlorine, dimethyl parabanic acid.is produced. This is
also formed in the oxidation of theine with chromic acid, while theobromine
yields methyl parabanic acid.

TRIVALENT (TRIHYDRIC) COMPOUNDS.

The trivalent compounds are derived from the hydrocarbons in
the same manner as the mono- and divalent ; three hydrogen atoms
are replaced by three monovalent groups. Their methods of for-
mation and transposition are also perfectly analogous to those of
the mono- and di-derivatives.

When three hydroxyl groups are introduced trivalent (trihy-
dric) alcohols are formed: —

CaHsCOH), = CH,(0H).CH(0H).CH2.0H.

Glycerol.

By the conversion of one primary alcoholic group, CHj.OH, into
carboxyl, we obtain the trivalent monobasic acids, in which two
alcoholic hydroxyls remain, hence they can be termed dioxy-mono-
carboxylic acids: —

■ ■■ CO.OH

'I

CH.OH = CH2(0H).CH(0H).C0.0H.

CH,.OH.

Trivalent Monobasic Acid,
Glyceric Acid or Dioxypropionic Acid.

The trivalent dibasic acids contain two carboxyl groups and one ,
alcohol group; hence may be called oxy-dicarboxylic acids : —

CO.OH

CH.OH = CHCOH^/^S'SS

I
CO.OH

CH(OH)(---g_

Trivalent Dibasic Acid,
Tartronic or Oxymalonic Acid.

TRIHYDRIC ALCOHOLS.

451

The tribasic acids, finally, contain three carboxyl groups : —
C3H,(CO,H)3.

Tribasic or Tricarboxylic Acid.

Many derivatives attach themselves to the trivalent alcohols and
acids.

TRIVALENT (TRIHYDRIC) ALCOHOLS.

. In these, three hydrogen atoms can be replaced by alcohol or
acid residues, forming ethers and esters: —

C,H

fOB

Job
(o.c

oh

OH

2 6
Ethyl Glycerol.

OH

fOH

C3hJo.c,h,
IO.C2H5

Diethyl Glycerol.
fOH

C3hJo.C,H30
lo.C.HjO

Diacetin.

The polybasic acids yield similar esters :-

C,H

OH
O.C.HjO

Monacetin.

fO.CjHs

C3HJo.C,H3

lo.C.H^

Triethyl Glycerol.

CsHa

Triacetin.

fOH

^i^A 0\c H O

Succinin.

fOH
C3HJ0H

(.O.SO3H
Glycerol Sulphuric
Acid.

(-01
sHJoI

'OH

OH

. i.PO(OH),

Glycerol Phosphoric

Acid.

The esters of the haloid acids, like

C3H3(0H)2C1

Monochlorhydrin.

C,H5(OH)CI,
Dichlorhydrin.

•^sHsClj,
Trichlorhydrin,

may be viewed as substitution products of the di- and trivalent
alcohols.

Glycerol, C3H5(OH)3, is the first member of the trihydric alco-
hols. Lower homologues cannot exist, because in general one car-
bon atom is capable of linking only one hydroxyl group in such a
manner that the hydrogen in it will be exchangeable in any further
replacement. Ethers and esters of trihydroxyl compounds, with
one and two carbon atoms, exist (p. 298).

The trihydroxyl derivatives are formed artificially in the same manner as the
mono- and di-hydroxyl compounds (p. 297). They can be obtained by oxidizing
the unsaturated alcohols with potassium permanganate (pp. 82, 297). Thus allyl
alcohol yields glycerol : — '

CH^iCH.CH^.OH + 0 + H^O = CH,(OH).CH(OH).CH2(OH).

Amyl glycerol, C,H5.CH(OH).CH(OH).CH2(OH), is obtained from ethyl viny
carbinol, C2H5.CH(OH).CH:CH2, etc. {Berichte, 21, Ref. 183 ; 22, Ref. 798).

452 ORGANIC CHEMISTRY.

Certain hydrates of the fatty acids, having constant boiling points at times (see
formic acid), may be considered as trihydroxyl derivatives ; hence, they have been
called ortho-acids : —

CHjOj + Hfi = CH(OH)s CH3.CO2H + H,0 = CH3.C(0H),,

Orthoformic Acid. Orthoacetic Acid.

just as the hydrate of nitric acid, NO3H -(- HjO = NOfOH),, is termed ortho-
nitric acid.

We get the esters of orthoformic acid by heating chloroform with an alcoholic
solution of sodium alcoholates : —

CHCI3 + sCHj.ONa = CH(O.CH3)3 + sNaCl;

or by the union of form-imido-ethers (p. 292) with alcohols, resulting in mixed
esters (Berichte, 16, 1645) : —

Cn{^-^^ + 2CH3.OH = Ch/oIcH, + NH.Cl.

When sodium mercaptides act on chloroform, we obtain esters of orthothio-
formic acid, e. g., CH{S.CH3)3.

Methyl Orthoformic Ester, (^H(0.CHj)3, boils at 102°, and has a specific
gravity 0.974 at 23°. The Triethyl Ester CH(O.C2H5)g, is an aromatic smell-
ing liquid, insoluble in water, and boiling at 146° ; sp. gr. 0.896. It decomposes
into ethyl formic, and ethyl acetic esters, when heated with glacial acetic acid.

The Triallyl Ester, CH(O.CgH5)3, formed by the action of metallic sodium
upon chloroform and allyl alcohol, boils about 200°.

Ethyl Orthoformic Ester, CH(S.C2H5)3, from sodium chloroform and sodium
mercaptide, is an oil with an odor like that of garlic. When oxidized it becomes
a disulphone, Q,\i^{%O^.C^W.^)^ (p. 307).

Methine Trisulphonic Acid, CH(S03H)3, is obtained by heating chloro-
picrin, CCl3(NO)2, with a concentrated aqueous solution of sodium sulphite, or
by heating calcium methyl sulphonate (p. 153) with fuming sulphuric acid. This
acid, like all sulphonic acids, is very stable and is not affected by boiling alkalies.

Ethyl Orthoacetic Ester, CHg.qO.CjH^Jj, triethyl acetyl ester, is ob-
tained by heating a-trichlorethane, CH3.CCI3, with an ethereal solution of sodium
ethylate. It boils at 142°, and when heated with water to 120° breaks up into
acetic acid and alcohol.

Isomeric with the preceding is

CH2.O.C2H5
Triethyl Ethenyl Ester, | . which is obtained from chloracetal,

CH(O.CjH5)2
CVi.fX.CVi{,O.QTA^\ (p. 305). It boils at 186°.

Glycerol, C3H8O3 = CsHsCOH,), glycerine, is produced 'in
small quantities in the alcoholic fermentation of sugar. It is pre-
pared exclusively from the fats and oils, which are glycerol esters of

GLYCEROL. 453

the fatty acids (p. 458). When the fats are saponified by bases or
sulphuric acid, they decompose, like all esters, into fatty acids and
the alcohol — glycerol. It is obtained synthetically from allyl tri-
bromide (p. 104) by converting the latter, with silver acetate, into
glycerol acetate and saponifying this ester with boiling alkahes : —

CH^Br CHj.O.C^H.O CH,.OH

I I I
CHBr yields CH.O.C,H,0 and CH.OH

II I
CHjBr CH2.O.C2H3O CHj.OH.

Glycerol is similarly formed "from glycerol trichloride (from pro-
pylene chloride) by heating it with water to 170°.

In preparing glycerol from fats (chiefly olive oil) the latter were formerly
saponified by boiling them with lead oxide and water. The aqueous solution of
glycerol was separated from the insoluble lead salt of the fatty acids (lead plaster,
p. 216), the dissolved lead precipitated by hydrogen sulphide and the filtrate con-
centrated by evaporation.

At present glycerol is produced in large, quantities in the manufacture of
stearic acid ; the fats are saponified by means of superheated steam, converting
them directly into glycerol and fatty acids. In most stearic acid factories sul-
phuric acid is employed for the saponification. The glycerol then exists as gly-
cerol-sulphuric acid (p. 454) in the aqueous solution. To liberate the glycerol the
solution is boiled with lime, the gypsum filtered off, the liquid concentrated and
distilled with superheated steam. In order to obtain a pure product the glycerol
is again distilled under diminished pressure.

Anhydrous glycerol is a thick, colorless syrup, of specific gravity
1.265 ^' '^S"- Under certain conditions it solidifies to a white,
crystalline mass, which melts at -(- 1 7°. Under ordinary atmospheric
pressure it boils at 290° (cor.) without decomposition ; under
diminished pressure, or with superheated steam, it distils entirely
unaltered. See Berichte, 17, Ref. 522, for the specific gravities
and boiling points of its aqueous solutions. It has a pure, sweet
taste, hence the name glycerol. It absorbs water very ener-
getically when exposed and mixes in every proportion with water
and alcohol, but is insoluble in ether. It dissolves the alkalies,
alkaline earths and many metallic oxides, forming with them, in all
probability, metallic compounds similar to the alcoholates (p. 126).

When glycerol is distilled with dehydrating substances, like sul-
phuric acid and phosphorus pentoxide, it decomposes into water and
acrolein (p. 199). It sustains a similar and partial decomposition
when it is distilled alone. When fused with caustic potash, it evolves
hydrogen, and yields acetic and formic acids. Platinum black, or
dilute nitric acid, oxidizes it to glyceric and tartronic acids, but
under energetic oxidation the products are oxalic acid, glycollic
acid, glyoxylic and other acids. Moderated oxidation (with nitric

454 ORGANIC CHEMISTRY.

acid, or bromine) produces g/yeerose, which consists chiefly of dipxy-
acetone, CO(CH2.0H)2. This unites with CNH and forms trioxy-
butyric acid {JBerichte, 22, io6 ; 23, 387). Phosphorus iodide or
hydriodic acid converts it into ally! iodide, isopropyl iodide and
propylene (p. 98). In the presence of yeast at 20-30° it ferments,
forming propionic acid.

Nitroglycerine, Trinitrin, glycerol nitric ester, C3H5(O.N02)3 (p. 302), is pro-
duced by the action of a n:)ixture of sulphuric and nitric acids upon glycerol. The
latter is added, drop by drop, to a well-cooled mixture of equal volumes of concen-
trated nitric and sulphuric acids, as long as it dissolves ; the solution is then poured
into water, and the separated, heavy oil (nitsoglycerine) is washed with water and
dried by means of calcium chloride.

Nitroglycerine is a colorless oil, of sp. gr. 1.6, and becomes crystalline at — 20°.
It has a sweet taste and is poisonous when taken inwardly. It is insoluble in water,
dissolves with diffipulty in cold alcohol, but is easily soluble in wood spirit and
ether. Heated quickly, or upon percussion, it explodes very violently (NobeVs
explosive oil) ; mixed with kiesetguhr it forms dynamite.

Alkalies convert nitroglycerine into glycerol and nitric acid ; ammonium sul-
phide also regenerates glycerol. Both reactions prove that nitroglycerine is not a
nitro-compound, but a nitric-acid ester.

Glycerol-Nitrite, CjH5(O.NO)3, is formed by the action of N^Oj upon gly-
cerol. It boils at 150° with_partial decomposition. Water breaks it up with evo-
lution of oxides of nitrogen. Its isomeride, Trinitropropane, C3H5(N02)3, is
obtained from glyceryl bromide by the action of silver nitrite. It is an oil, boil-
ing at 200°. , ,Qjj>

Glycerol-Sulphuric Acid, C3H5 < k cr) ^ti) 's formed by mixing i part gly-
cerol with r part of sulphuric acid. The free acid decomposes when its aqueous
solution is heated. Its salts are readily soluble ; the calcium salt is crystalline.

Glycerol-Phosphoric Acid, CjHj/k pQ ti , occurs combined with the

fatty acids and choline as lecithin (see this) in the yolk of eggs, in the brain, in
the bile, and in the nervous tissue. It is produced on mixing glycerol with meta-
phosphoric acid. The free acid is a stiff syrup, which decomposes into glycerol
and phosphoric acid when it is heated with water. It yields easily soluble salts
with two equivalents of metal. The calcium salt is more insoluble in hot than in
cold water ; on boiling its solution, it is deposited in glistening leaflets.

HALOID ESTERS OF GLYCEROL.
Monocklorhydrins, C3H5(OH)jCl. There are two possible isomerides : —

CH2(OH).CH(OH).CH2Cl and CH2(0H).CHC1.CH2.0H.
a-Chlorhydrin. /3-Chlorhydrin.

a-Chlorhydrin is produced, together with a little of the ^-variety, on heating
glycerol and hydrochloric acid to 100°. It is best prepared by heating epichlor-
hydrin (p. 456) with water (i molecule) to 120° (Berichte, 13, 457). It is a thick
liquid, soluble in water, alcohol and ether ; it boils with partial decomposition at
215°- Sodium amalgam converts it into propylene glycol; and when oxidized, it
becomes j3-chlorlactic acid.

HALOID ESTERS OF GLYCEROL. 455

^-Chlorhydrin is obtained from allyl alcohol by the addition of hypochlorous
acid. It boils at 230°.

Dichlorkydrins, C3H5(OH)Cl2 {Dichlorpropyl Alcohols) :—

CH2Cl.CH(OH).CHja and CHjCl.CHCl.CHj.OH.

d-Dichlorhydrin. /3-Dichlorhydrin.

a-Dichlorhydrin is produced by the action of hydrochloric
acid or chloride of sulphur upon glycerol. It is obtained perfectly
pure by shaking epichlorhydrin (p. 456) with concentrated hydro-
chloric acid.

Preparation. — Saturate a mixture of glycerol (3 parts) and glacial acetic acid
(2 parts) with hydrochloric acid gas, accelerating the absorption toward the end
by applying heat. The strongly fuming product is washed with a soda solution
and the separated oil distilled. The portion going over from 160-200° contains
a-dichlorhydrin and acetochlorhydrin. These are difficult to separate [Annalen,
208, 361). Therefore, epichlorhydrin is first prepared from the crude dichlor-
hydrin by adding pulverized caustic soda gradually to the portion which distils at
170-180°, so that the temperature does not exceed 130°. The resulting epichlor-
hydrin is distilled off (^i?r2V/4z'^, 10, 557) and changed to a-dichlorhydrin by shaking
with concentrated hydrochloric acid.

a-Dichlorhydrin is a liquid, with ethereal odor, of sp. gr. 1.367
at 19°, and boils at 174°. It is not very soluble in water (in 9
parts at 19°), but dissolves readily in alcohol and ether. When
heated with hydriodic acid it becomes isopropyl iodide ; sodium
amalgam produces isopropyl alcohol. Chromic acid oxidizes it to
^-dichloracetone (p. 205) and chloracetic acid.

When sodium acts on an ethereal solution of a-dichlorhydrin, we do not get

trimethylene alcohol, | ")CH.OH, but allyl alcohol as a result of molecular

CH/
transposition {Berichie, 21, 1289).

/S-Dichlorhydrin, CH^Cl.CHCl.CH^.OH, obtained by adding
chlorine to allyl alcohol, or hypochlorous acid to allyl chloride, boils
at 182-183°; its sp. gr. = 1.379 at 0°. Sodium converts it into
allyl alcohol. Fuming nitric acid oxidizes it to a/J-dichlorpro-
pionic acid.

Both dichlorhydrins are changed to epichlorhydrin by the
alkalies.

Trichlorhydrin, C3H5CI3, is made by the action of PCI5 upon
both dichlorhydrins, and has already been described, p. 104, as
glyceryl trichloride.

a-Monobroinhydrin,C3H5(OH)2Br,is formed when HBr acts on glycerol. It
is an oily liquid, which boils at 180° under diminished pressure (Berichie, 21, 2890).

a-Dibromhydrin, CH2Br.CH(OH).CH2Br, is an ethereal-smelling liquid,
which boils at 219°; its sp, gr. at 18° is 2.1 1.

45^ ORGANIC CHEMISTRY. ^

/3-Dibroinhydrm, CHjBr.CHBr.CHj.OH, boils at 212-214°.

Tribromhydrin, CjHjBrj, is described on p. 104. a-Monoiodhydrin, CjHj
(OH)^!, is obtained by heating glycerol and HI to 100°; it is o. thick liquid of
sp. gr. 1.783. I

a-Di-iodhydrin, CH2l.CH(OH).CH2l, is prepared by heating a-dichlorhy- '
drin with aqueous potassium iodide. A thick oil of specific gravity 2.4 and \
solidifying at — 15°. 1

GLYCIDE COMPOUNDS.

By this designation we understand certain compounds formed
from glycerol derivatives by the exit of H^O or HCl. These are
again readily converted into glycerol derivatives.

Epichlorhydrin, C3H5OCI, is isomeric with monochloracetone,
and obtained from both dichlorhydrins (p. 455) by the action of
caustic potash or soda (analogous to the formation of ethylene oxide,
from glycolchlorhydrin, (p. 302) : —

CH^Cl CH,\

I 1 °

CH.OH + KHO = CH / -f KCl + H^O.

CHjCl CH^Cl

It is a very mobile liquid, insoluble in water and boils at 117".
Its sp. gravity at 0° is 1.203. ^'^ odor resembles that of chloro-
form, and its taste is sweetish and burning. It forms a-dichlorhy-
drin with concentrated hydrochloric acid. PCI5 converts it into
trichlorhydrin. Continued heating with water to 180° changes it
to a-monochlorhydrin. Concentrated nitric acid oxidizes it to
/J-chlorlactic acid.

Like ethylene oxide, epichlorhydrin combines with sodium bisulphite, and with

CNH to the oxycyanide, C^HjClcf „^ . Hydrochloric acid changes the latter to

an acid. Epicyanhydrin, C3H5.O.CN, is formed when CNK acts on epichlorhy-
drin. Brilliant crystals which fuse at 162.3°, ^°<i become Epihydrin-carboxylic
Acid, C3H5O.CO2H, under the influence of HCl {Berichle, 15, 2586).

The ethers of chlorhydrin, like C,H5Cl(OH)O.C2H5, are produced on warm-
ing epichlorhydrin with alcohols. When they are distilled with caustic potash
glycide ethers appear :

CHg.Cl CHov

CH.OH + KOH = CH ^ + KCl + H.O.

I I

CH^.O.C.H^ t^^.o.c^n^

Ethyl Glycide Ether, C3H5O.O.C2H5 (Epiethylin), boils at 126-130°; amy!
glycide ether, CsH,O.O.CsH„, at 188°.

Acetic Glycide Ester, C3H5O.O.C2H3O, is produced by heating epichlorhy-
drin with anhydrous potassium acetate. It boils at 168-169°.

ALCOHOL ETHERS OF GLYCEROL. 457

Glycide Alcohol, CjHjO.OH, is formed by the decomposition of its acetate
by caustic soda or baryta. It boils near 162° and is miscible with water, alcohol
and ether ; its specific gravity is i . 1 65 at 0°. It reduces ammoniacal silver solu-
tions at ordinary temperatures. This is also true of its acetic ester.

When epichlorhydrin is heated with sodium acetate and absolute alcohol, the
reaction proceeds as follows : —

C3H50Cl+C2H302Na+C2H5.0H = C3H50.0H + C2H302.C2H5 + NaCl

The glycide formed at first condenses to polyglycides, chiefly diglycide (C3H5O.
OH) 2, which boils at 250° (p. 459).

Glycidic Acid, CjH^Oj, an oxide or anhydridic acid, is formed (similar to
epichlorhydrin) from /3-chlorlactic acid and achlorhydracrylic acid, when treated
with alcoholic potash or soda : —

CH^Cl CH^.OH CH,.

I I I >o.

CH.OH and CHCl yields CH /

I I I

CO.OH CO.OH CO. OH.

j3-Chlorlactic Acid. a-Chlorhydracrylic Acid. Glycidic Acid.

When separated firom its salts by sulphuric acid, it is a mobile liquid, miscible
with water, alcohol and ether. It volatilizes when heated and possesses a pun-
gent odor. Its potassium salt, C3H3KO3 + ^H^O, forms warty, crystalline
aggregates. Ferrous sulphate does not color the acid or its salts red (distinction
from the isomeric pyroracemic acid). It combines with haloid acids to form
/3-halogen lactic acids, and on warming yields glyceric acid.

Its ethyl ester, obtained by the action of ethyl iodide upon its silver salt, is a
liquid, with an odor resembling that of malonic ester. It boils at 162°.

See p. 461 for the homologous glycidic acids.

Epibromhydrin, C3H50Br, from the dibromhydrins, is analogous to epichlor-
hydrin and boils at 130-140°.

Epi-iodhydrin, C3H5OI, results from the treatment of epichlorhydrin with a
solution of potassium iodide, and boils at 160°.

ALCOHOL ETHERS OF GLYCEROL.

Mixed ethers of glycerol with alcohol radicals (p. 299) are obtained by heating
the mono- and dichlorhydrins with sodium alcoholates : —

C3H,{gj^ + 2C,H3.0Na = C3H,{OH,,H,),+ ^^aCI.
Monoethylin, C3H5 I '^qq\ , is soluble in water, and boils at 230°. Di-

ethvlin C,'hA9^^ n \ , dissolves with difficulty in water, has an odor re-

sembling that of peppermint, and boils at 191°; its specific gravity is 0.92. When
its sodium compound is treated with ethyl iodide we obtain Triethylin, C3H5
(O.C2H5)3, insoluble in water and boiling at 185°

AUylin, C3H5|l?^^j^ , monoallyl ether^, is produced by heating glycerol

with oxalic acid, and is present in the residue from the preparation of allyl alcohol
(p. 134). It is a thick liquid, boiling at 225-240°.

458 ORGANIC CHEMISTRY.

A compound of the formula, C^Hj^^Og, and designated glycerin ether,
(CljHj)^©,, occurs with allylin, and boils at 169-172° (see Berichte, 14, 1496 and
2270).

ACID ESTERS OF GLYCEROL.

By replacing i, 2 and 3 hydrogen atoms in glycerol with acid
radicals we obtain the so-called mono-, di-, and triglycerides. They
are formed when glycerol and fatty acids are heated to 100-300°;
whereas in the action of acid chlorides upon glycerol, esters of the
chlorhydrins (p. 455) are produced : —

C3H5(OH)3 + C^H^aCl = C3H,Cl(OH)(O.C,H30) + H,0.

When the acid glycerides are acted upon with alkalies, lime water,
or lead oxide, they all revert to glycerol and salts of the fatty acids
(soap) (p. 216). Concentrated sulphuric acid decomposes them
into free acids and glycerol sulphuric acid (p. 454).

Monoformic Ester, C3H5 \ 0 CHO' Monoformin, is produced by heating

glycerol with oxalic acid (p. 217). It distils near 200°, and decomposes partly
into ally! alcohol, carbon dioxide and water ; it distils without decomposition in
a vacuum. /^)H^

Monacetin, C3H5 | K f h O' '^ formed on heating glycerol with glacial

acetic acid to 100°. It is a liquid which dissolves readily in water and ether,

r OTT
Diaceiin, C3H5.J fO C H 01 > is obtained from glycerol and glacial acetic acid

when they are heated to 200°. It boils at 280°.

Triacetin, C3H5(O.C2H30)3, is prepared by prolonged heating of diacetin
with an excess of glacial acetic acid to 250° ; it boils at 268°. It is found in
slight quantities in the oil of Euonymus europaus.

Tributyrin, C3H5(O.C4H,0)3, occurs along with other higher triglycerides
in cow's butter.

The glycerides of the higher fatty acids, Cn HunOj, and those of the oleic acid
series, C^}iiia-..^0^, occur in the natural fatty oils, fats, and tallows; they can be
obtained artificially by heating glycerol with the acids.

Monopalmitin, C3H5 ■[ IPirJ^ melts at 58°. Dipalmitin, C3H5

1 CO C H 0^ ' ^' S9°- Tripalmitin, C3H5(O.Cj3H3jO)3, is found in most

fats, especially in palm oil, from which it can be obtained by strong pressing and
recrystallization from ether. It separates from olive oil when the latter is strongly
cooled. It crystallizes from ether in pearly, glistening laminae, which melt at 63°.
By repeated fusion and solidification the melting point falls quite considerably.
Like all higher triglycerides, it is not very soluble in alcohol.

Trimyristin, or Myristin, CjHjIO.Ci^Hj, 0)3, glycerol myristic ester, oc-
curs in spermaceti, in muscat butter, and chiefly in oil nuts (from Myristica surina-
mensis), from which it is most readily obtained (^Berichte, 18, 201 1). It crystal-
lizes from ether in glistening needles, melting at 55°. It yields myristic acid (p.
215) when saponified. •

Tristearin, C3H5(O.Ci3H350)3, occurs mainly in solid fats (tallows). It can
be obtained by heating glycerol and stearic acid to 280-300°. It crystallizes from

POLYGLYCEROLS. 459

ether in shining leaflets, and melts at 66.5°. Its melting point is also lowered by
repeated fusion.

Triolein, C3H5(O.CjgH3jO)3, is found in oils, like olive oil. It solidifies at
— 6°. It is oxidized on exposure to the air. Nitrous acid converts it into the
isomeric elaidin, which melts at 36° (p. 243).

Nearly all the natural fatty oils and fats (tallows) of animal and
vegetable origin are mixtures of the triglycerides of the fatty acids.
The former are chiefly triolein, the latter (beef tallow, sheep tallow,
cocoa butter, etc.), tristearin and tripalmitin. They are insoluble
in water, dissolve with difficulty in alcohol, readily in ether, carbon
disulphide, benzene ether, etc. They are lighter than water and
swim upon it. They form spots on paper which do not disappear
when heated — distinction from the volatile oils. They are not
volatile, and decompose when strongly heated.

The fatty oils are distinguished as drying and non-drying oils.
The former oxidize readily in the air, are coated with a film and
become solid; they comprise the glycerides of the unsaturated
acids — linoleic and ricinoleic acids (p. 243). The non-drying oils
are glycerides of oleic acid ; the production of free acid in them
is the cause of their becoming rancid. Among the drying oils are
limeed oil, hemp oil, walnut oil, castor oil, etc. Non-drying oils
are olive oil, rape-seed oil (from Brassica campestris), also from
the oil of Brassica rapa, almond oil, train oil and cod oil.

Boiling alkalies saponify all the fats.

SULPHUR DERIVATIVES OF GLYCEROL.

Glycerol mercaptans are formed on heating the chlorhydrins with an alcoholic
solution of potassium sulphydrate ; — ■

C3H5CI3 + 3KSH = CaH^CSH), + 3KCI.

The hydrogen atoms in the SH groups can be replaced by heavy metals.
Hydrochloric acid precipitates them in the form of thick oils. When oxidized
they yield sulpho-acids, which may be prepared from the chlorhydrins by means of
alkaline sulphites.

POLYGLYCEROLS.

They are obtained like the polyglycols (p. 304), viz., by the union of several
molecules of glycerol and withdrawal of water. To obtain them, glycerol
(diluted % with water), is saturated with HCl and heated to 130° for some hours ;
or glycerol and monochlorhydrin are heated together. They are thick liquids,
which can be separated from each other by distillation under diminished pressure.
When heated with solid caustic potash they sustain further loss of water and
become polyglycides (p. 457) : —

Diglycerol. Diglycide.

fOH

l"5 J O

i^^5 (oh

460 ORGANIC CHEMISTRY.

Of the higher trihydric alcohols which have been prepared, we have : Butyl
glycerol, C4Hi„03 = CH3.CH(OH).CH(OH).CHj.OH, from the bromide of
crotyl alcohol, by boiling it with water. It is a thick, sweet liquid, boiling at
172-175° under 27 mm. pressure.

Hexyl Glycerol, C(;Hi403. There are three isomeric derivatives of this class,
obtained from the corresponding unsaturated, monohydric alcohols, CgH j 2O, by the
addition of bromine, and then boiling with water. They are thick liquids, readily
soluble in water [Berichie, 22, Ref. 788).

Other glycerols have been obtained by oxidizing unsaturated monohydric alco-
hols with potassium permanganate (p. 45 1 ) .

MONOBASIC ACIDS, C.H^^O^.

The acids of this series bear the same relation to the glycerols,
that the lactic acids bear to the glycols. They, too, can be re-
garded as dioxy-fatty acids (p. 345).

They may be synthetically prepared by the common methods
used in the production of oxyacids (p. 346), also by oxidizing un-
saturated acids with potassium permanganate (p. 236) [Berichte,2,x,
Ref. 660).

The first and lowest dioxyacid (p. 330) has been described as glyoxylic acid,
(dioxyacetic acid). Both free and in its salts it has one molecule of water firmly
combined: CHO.COOH -4- H^O = CH(OH)2.C02H. However, the two
hydroxyl groups do not manifest the usual reactions, but split off water with for-
mation of the aldehyde group.

Glyceric Acid, CsHgO^ (dioxypropionic acid), s formed : (i)
by the careful oxidation of glycerol with nitric acid : —

CH2(OH).CH(OH).CH2(OH) -f O^ = CH2(0H).CH(0H).C0.0H + H^O;

(2) by the action of silver oxide upon /5-chlorlactic acid, CH^Cl.
CH(OH).C02H, and a-chlorhydracrylic acid, CH2(0H).CHC1.
CO2H (p. 457) ; (3) b/ heating glycidic acid with water (p. 457).

Preparation. — A mixture of I volume of glycerol and I volume of water is
placed in a tall glass cylinder and then i part HNO3 (sp. gr. 1.5) is introduced
by means of a funnel whose end reaches to the bottom of the vessel. Two layers
of liquid form and the mixture is permitted to stand for several days at 20°, until
the layers have completely united. The liquid is then evaporated to syrup con-
sistence, diluted with water, saturated while boiling with calcium carbonate and
some lime water added, to precipitate any impurities. When the filtrate is con-
centrated calcium glycerate separates in warty crusts. It is decomposed with
oxalic acid, filtered from the separated oxalate and the filtrate boiled^ with lead
oxide to remove all excess of oxalic acid. Hydrogen sulphide precipitates the
lead in this filtrate and the liquid is then concentrated upon a water bath (Berichie,
9, 1902, 10, 267, 14, 2071).

The acid may be obtained in small quantities by oxidizing glycerol with mer-
, curie oxide and baryta water [Berichte, 18, 3357).

(GLYCERIC ACID. 46 1

Glyceric acid forms a syrup which cannot be crystallized. It is
easily soluble in water and alcohol. It is optically inactive, but
as it contains an asymmetrical carbon atom (p. 63), it may be
changed to active Isevo-rotatory glyceric acid by the fermentation
of its ammonium salt, through the agency of Penicillium glaucum
(P- 357)-

Its calcium salt (CjHjOjjjCa -)- aHjO, crystallizes in warty masses, consisting
of concentrically grouped needles. It dissolves readily in water but not in
alcohol. The lead salt, (C3H504)2Pb, is not very soluble in water. The ethyl
ester, CjHjOj.CjHj, is formed on heating glyceric acid with absolute alcohol. It
is a thick liquid of sp. gr. 1.193 ^t 0°, and boils at 230-240°.

When the acid is heated to 140° it decomposes into water, pyro-
racemic and pyrotartaric acids. When fused with potash it forms
acetic and formic acids, and when boiled with it yields oxalic and
lactic acids. Phosphorus iodide converts it into /3-iodpropionic
acid. Heated with hydrochloric acid it yields a-chlorhydracrylic
acid and a/9-dichlorpropionic acid.

When glyceric acid is preserved awhile it forms an ester-like modification or
anhydride, (0311^03)2 (?). This is sparingly soluble and crystallizes in fine needles.
When boiled with water it again reverts to the original acid.

Amido-glycerol, or Serin, CH2(OH).CH(NHj).C02H, a-amidohydracrylic
acid, is obtained by boiling serecin with dilute sulphuric acid. It forms hard
crystals, soluble in 24 parts of water at 20°, but insoluble in alcohol and ether.
Being an amido-acid it has a neutral reaction, but combines with both acids and
bases. Nitrous acid converts it into glyceric acid.

Isomeric ^amido-lactic acid, CHj(NH2).CH(OH).C02H, is obtained from
;3-chlorIactic acid and glycidic acid by the action of ammonia (Berichte, 13, 1077).
It dissolves with more difficulty in water than serin.

The Hydrate of trichlorpyroracemic acid, CCl3.CO.COjH + H^O, may be
considered as isotrichlorglyceric acid, CClg.C(OH)2.C02H. It is formed from
trichloracetyl cyanide, CCI3.CO.CN, by the action of hydrochloric acid (p. 332).
It crystallizes in long needles, melts at 102° and distils undecomposed. It
reduces ammoniacal silver solutions and alkaline copper solutions. An interest-
ing method of forming it (along with tricarballylic acid) consists in the action
of KCIO3 and hydrochloric acid upon gallic acid, saUcylic acid and phenol
{Berichte, 13, 1938).

Mention may b.e made of the following higher dioxyacids : —

The dioxybutyric acids, C^HgO^, are known in three isomeric forms :
(I) o^-Dioxybutyric Acid, CH3.CH(OH).CH(OH).C02H, ^-Methylgly-
ceric Acid, is prepared fi-om a/S-dibrombutyric acid on boiling it with water, or
upon digesting /3-methyl glycidic acid (see below) with water. A thick liquid,
gradually becoming solid and crystalline. It melts at 80° C. Its corresponding
^-Methyl glycidic acid, CH3.CH.CH.CO2H (p. 457), has been obtained from

\ /
O
chloroxybutyric acid (m. p. 62-63°, from normal crotonic acid and ClOH) by
the action of alcoholic potash. It crystallizes in rhombic prisms, melting at 84°

462 ORGANIC CHEMISTRY.

(Annalen, 234, 204). The . same acid is also formed from the chloroxybutyric
acid melting at 82-85° (from isocrotonic acid by addition of ClOH and from
/3-methyl glycidic acid with HCl) (Annalen, 234, 221). It yields a^dioxybutyric
acid when heated with water.

(2) ^Sy-Dioxybutyric Acid, CH2(OH).CH(OH).CH2.C02H, butyl glyceric
acid, from a-chlorhydrin (p. 454), HCN and HCl, is a thick liquid, which passes
into an anhydride (oxybutyrolactone) at 100° C.

(3) Dioxyisobutyric Acid, '-•^2(°^^\c(OH).C02H,a.methyl glyceric acid,

results upon warming a-methyl glycidic acid with water to 100°. It crystallizes
after long standing and melts at 100°. The a-methyl glycidic acid corresponding
to it, has been obtained from chloroxyisobutyric acid (melting at 106-107°, fr°™
methacrylic acid p. 457, by addition of CIOH) when acted upon by alcoholic
potash. It is a thick liquid. It combines with HCl to form chloroxyisobutyric
acid.

The following acids have been obtained by oxidizing unsaturated fatty acids
with potassium permanganate :-

Dioxyundecj'
melts at 84-86°.

Dioxybehenic Acid, C22Hj5,(OH)j02, from erucic acid, CjjH^jOj, melts at 133°.

Dioxystearic Acid, CjgH3^(OH)j02, from oleic acid, CigHj^Oj, melts at 136°
[Berichte, 22, 743).

DIBASIC OXY-ACIDS, QH,,_,a5.

We can regard these as derivatives of the dibasic acids,
C„H2„(C02H)2, from which they are obtained by the introduction
of one OH-group for one atom of hydrogen (p. 345). Those
oxydicarboxylic acids, in which the hydroxyl group occupies the
^-position with reference to one of the two carboxyls, a-oxyglu-
taric acid (p. 467) excepted, immediately decompose when set free
into water, — and lactonic acids or lactone carboxylic acids (see
itamalic acid, p. 468). . Such lactonic acids can be directly pre-
pared synthetically by digesting the aldehydes with sodium succin-
ate in the presence of acetic anhydride {Berichte, 18, 2523; 23,
Ref. 8s) :—

CO2H

/
CH,.CO,H = CH,.CH.CH.

\

CH3.CHO + I

Acetaldehyde. CH^.COaH
Succinic
, Acid. '

CH2 -f H2O.

O CO

Methyl Paracoiiic Acid.

Ethyl paraconic acid is formed, in a similar manner, from suc-
cinic acid and propionic aldehyde, and propionparaconic acid
from succinic acid and butyraldehyde.

TARTRONIC ACID. 463

The reaction probably proceeds in a manner analogous to that of aldehyde
upon aceto-acetic ester and malonic ester. First, unsaturated acids are produced.
These undergo a rearrangement of atoms and become lactonic acids. This is
analogous to the conversion of allylacetic acid into valerolactone. Or, they can
also be obtained from the corresponding unsaturated dicarboxylic acids by mole-
cular transposition (when acted upon by hydrobromic acid) (see allyl malonic
acid, p. 430, and allyl succinic acid, p. 430). The aldehydes also react with pyro-
racemic acid. Two isomeric lactonic acids result (Berichte, 23, Ref. 90). When
neutralized in the cold with caustic alkali, or with alkaline carbonates, the lactonic
acids from the oxydicarbonic acids usually form monobasic salts with the free car-
boxyl group, whereas when boiled with alkalies dibasic salts of the oxydicarboxylic
acids result. Heated alone, or when boiled with dilute sulphuric acid, the lactonic
acids split up into CO^ and lactones, which are in part converted into the isomeric
/3y-unsaturated acids (p. 352) ; unsaturated dibasic acids are formed at the same
time. The lactonic acids derived from pyroracemic acid yield carbon dioxide
and unsaturated hydrocarbons when they are distilled. Lactones and unsatu-
rated agids are also formed {Berichte, 23, Ref. 91).

I. Tartronic Acid, C3H A = CH(OH):^^q^^, oxymalonic

acid, is produced from chlor- and brom-malonic acid, CHC1(C02H)2,
by the action of silver oxide or by saponifying their esters with
alkalies ; from mesoxalic acid, CO(C02H)2, by the action of sodium
amalgam; from dibrompyroracemic acid, CHBrj.CO.COjH, when
digested with baryta water ; from glycerol by oxidation with potas-
sium peynanganate. Also from glyoxylic acid, CHO.CO2H, by
the action of CNH and hydrochloric acid, and from nitro-tartaric
acid, and dioxytartaric acid, as well as from trichlorlactic acid
when the latter is digested with alkalies.

Preparation. — Nitrotartaric acid is gradually introduced into warm aqueous
alcohol {Berichte, \o, 1789). Abetter method consists in adding trichlorlactic
ester (p. 360) to a warm sodium hydroxide (4 molecules) solution. After acidu-
lation wiflr acetic acid barium chloride is added to precipitate barium tartronate,
and this is then decomposed with sulphuric acid. To obtain the ethyl ester mix
the barium tartronate with alcohol and saturate with hydrochloric acid gas {Be-
richte, 18, 7S4, 2852).

Tartronic acid is easily soluble in water, alcohol and ether, and
crystallizes in large prisms. When pure it melts at 184°, decom-
posing into carbon dioxide and glycolide, (Q^^O^^- (Berichte, 18,

756)-
The calcium salt, CsH^OjCa, and barium salt, CjHjOsBa + 2HjO,

dissolve with difficulty in water and are obtained as crystalline

precipitates. The ethyl ester, CHjOsCQHs)^ (^ee above) is a liquid

boiling at 219".

Tartramic Acid, CH(NH2).(C02H)j, was described on p. 409 as amidomalonic
acid.

464 ORGANIC CHEMISTRY.

CH,.CO,H
2. Malic Acid, QH^Os = | Oxysuccinic Acid,

CH(OH).CO,H,
{Acidum malicuni), occurs free or in the form of salts in many plant
juices, in unripe apples, in grapes and in mountain-ash berries
(from Sorbus aucuparid). It is artificially prepared by the action
-of nitrous acid upon "asparagine or aspartic acid (p. 466) ; by boil-
ing bromsuccinic acid with silver oxide : —

C,H3Br/™2^H + ^gOH = C,H3(0H)/^g»g + AgBr;

by the reduction of tartaric and racemic acids with hydriodic acid
(p. 411) ; by heating fumaric acid with caustic soda to 100° or with
water to 200° ; and by saponifying the esters of chlorethenyltri-
carboxylic acid (p. 471).

The best source of malic acid is the juice of unripe mountain-ash berries.
This is concentrated, fihered, and while boiling saturated with milk of lime. The
pulverulent lime salt which separates is dissolved in hot dilute nitric acid (i part
HNO3 in 10 parts water) ; on cooling acid calcium malate crystallizes from the
liquid. To obtain the pure acid, the lead salt is prepared and decomposed with
hydrogen sulphide [Annalen, 38, 259).

Malic acid forms deliquescent crystals, which dissolve readily in
alcohol, slightly in ether, melt at 100°, and at 140° lose water and
pass into fumaric and maleic acids (p. 425).

It exists in three different modifications ; these are identical in
structure {Berichte, 18, 2170, 2713). They are chiefly distinguished
,by their optical deportment. As malic acid contains an asymmetric
carbon atom, it is possible for it, according to van' t Hoff's theory,
to appear in three forms — a laevo-rotatory, a dextro-rotatoryTaiid ah
inactive (para) form. The latter can be resolved into the active
varieties.

The natural malic acid (from mountain-ash berries) rotates the
plane of polarization to the left, that obtained from dextrotartaric
acid and aspartic acid turns it to the right ([a]„ = 3.3°). The
variety obtained from fumaric and chlorethenyltricarboxylic acids is
inactive and melts at 130-135° {Annalen, 214, 50). The inactive
acid, formed in the reduction of racemic acid, fumaric acid and >
maleic acid, can be resolved, by means of the cinchonine salt, into
a dextro- and Isevo-rotatory malic acid {Berichte, 18, Ref. 537).

Succinic acid is formed by the reduction of malic acid. This is
accomplished by the fermentation of the lime salt with yeast, or by
heating the acid with hydriodic acid to 130° (p. 411). When it is
warmed with hydrobromic acid, it forms monobrom-succinic acid.
Bromine converts malic acid into bromoform and carbon dioxide.

MALIC ACID. 465

When the acid is heated to 180° it decomposes into water, fumaric
acid, maleic acid and maleic anhydride (p. 427). The coumarines are
produced when the acid is heated with phenols and sulphuric acid.
This result is probably to be explained by assuming that the malic
acid first changes to the first aldehyde of malonic acid, CHO.CH2.
CO2H, and this then condenses with the phenols {^Berich(e,\'j, 1647).
When malic acid is heated alone, or with sulphuric acid or zinc
chloride, the product is cumalic acid (see this).

The neutral alkali malates do not crystallize well and soon deliquesce; the
primary salts, however, do crystallize. Iheprimary ammonium salt, Q,^^(^^^^0^,
forms large crystals, and when exposed to a temperature of 160-200°, becomes
fumarimide, C^^HjOj.NH.

Neutral Calcium Malate, C^H^OjCa + HjO, separates as a crystalline powder
on boiling. The acid salt, (QHjOjjjCa + SH^O, forms large crystals which are
not very soluble [Berichte, 19, Ref. 679). Sugar of lead precipitates an amorphous
lead salt from the aqueous solution. This melts in boiling water.

Sodium Brommalate (from the acid, CjHjBrOj), is formed when the aqueous
solution of sodium dibromsuccinate is boiled; milk of lime transforms it into
tartaric acid.

The diethyl ester, Q.fif(^.^^^c,, suffers partial decomposition when boiled.

( C\ c w o
Acetyl chloride converts it into ethyl aceto-malate, C2H3-< ,^f^ C "R \ ' w^'*^^

boils at 258°.

Consult Berichte, 18, 1952, for the boiling temperatures of the malic acid esters.

As an isomeride of malic acid, may be mentioned : —

a-Oxyisosuccinic Acid, CH3.C(OH).(C02H)2, Methyl Tartronic Acid,
which is formed from pyroracemic acid, CH3.CO.CO2H, by means of CNH, etc.
Isomalic acid, obtained from bromisosuccinic acid by the action of silver oxide, is
probably identical with the preceding. Both decompose at 178° into carbon di-
oxide and a-lactic acid.

Its ethyl ester, CH3.C(O.C3H5)(C02H)2, and not methylene-malonic acid (p.
428), is formed when bromisosuccinic acid is acted upon with alcoholic potash.

p-Oxyisosuccinic Acid, CH2.0H.CH.(C02H)2. Its ethyl ester is produced
when methylene-malonic ester (p. 428) is saponified with alcoholic potash {Be-
richte, 23, Ref. 194).

Amides of Malic Acid : — ,

Malamic Acid. Malamide.

C^HjCNH^X^^O^^ C2H3(NH2)^(,qjjjj^ '-2^3(.^"2)\cO.NH2-
Aspartic Acid. Asparagine. Triamide (unltnown).

Aspartic acid bears the same relation to malic and succinic acids, as glycocoll
bears to glycoUic aciS and acetic acid {p. 366) ; hence, it may be called amido-
succinic acid.
39

466 ORGANIC CHEMISTRY.

Malamide, C^HgOgN,, is formed by the action of ammonia upon dry ethyl
malate. It forms large crystals. When heated with water, it breaks up into malic
acid and ammonia, thus plainly distinguishing itself from isomeric asparagine.

Ethyl Malamate, CjHalOH)/ „9'-'^z , is obtained by leading ammonia

into the alcoholic solution of malic ester ; it forms a crystalline mass.

CH(NH2).C02H
Aspartic Acid, C4H,N0i= | , amidosuccinic

CH,.CO,,H
acid, occurs in the vinasse obtained from the beet root, and is
procured from albuminous bodies in various reactions. It is pre-
pared by boiling asparagine with alkalies and acids {Berichte, 17,
2924).

It may be synthetically formed as follows: By the reduction of isonitroso-
succinic acid (the oxime of oxalacetic acid, p. 435) with sodium amalgam; by
heating fumaric and maleic esters to 110° with alcoholic ammonia [Berichte, 21,
86, 644) ; and by hestfing fumarimide and maleimide with water : C^H202:NH -f
2H2O := C^HjNO^. As it contains an asymmetric carbon atom, it can (like
malic acid) exist in a Isevo-rotatory, dextro-rotatory and inactive variety. Naturally
occurring aspartic acid is Isevo-rotatory ; it crystallizes in rhombic prisms, or leaflets,
and dissolves with difficulty in water (in 256 parts at 10° and in 18 parts at 100°).
The synthetic acid is inactive. It is more soluble in water, and consists of mono-
clinic crystals. Active aspartic acid is changed to the inactive form by heating it
with hydrochloric acid to 180°. Like glycocoU it combines with alkalies and
acids yielding salts ; with the former it yields acid and neutral salts, c. g., C^Hj
NO^Na -f HjO and [C^n^■^0^\^^. + sHp.

Nitrous acid changes it to malic acid: —

C,H3(NH,)/^g2j yields C,U,{OU)(^^^;

from the active variety there results the active malic acid, and from the inactive,
the inactive malic modification.

CHCNHO.CO^H
Asparagine, CiHgNaOa =1 , the monamide of

CH2.CO.NH2
aspartic acid,. is found in many plants, chiefly in their seeds; in
asparagus, in beet-root, in peas and beans, etc. It often crystal-
lizes from the pressed juices of these plants after evaporation. It
is artificially produced when bromsuccinic ester is heated to 100°
with ammonia {Berichte, 20, Ref. 152), or by the Action of alco-
holic ammonia upon aspartic ester {Berichte, 20, Ref. 510; Berichte,
22, Ref. 243). Natural asparagine forms shining, four-sided, rhom-
bic prisms, containing one molecule of water, and is readily solu-
ble in hot water, but not in alcohol ,or ether. Its aqueous solution
is laevo-rotatory. Dextro-a.spa.i:a.g'me, from the sprouts of vetches,
has been produced on heating inactive aspartic ester with alcoholic
ammonia. It differs from ordinary asparagine in having a sweet

OXY-PYROTARTARIC ACIDS. 467

taste, and in forming right-hemihedral crystals {Berichie, 19, 1691).
It forms salts with bases and acids (i equivalent). It changes to
aspartic acid, giving off ammonia, when it is boiled with water ;
the conversion is more speedy when alkalies or acids are employed.
Nitrous acid converts it into malic acid : —

CH(NH,).C02H _ ' CH(0H).C02H

I yields I

CH^.CO.NHj CHj.COjH

It forms ammonium succinate when it ferments in the presence
of albuminoids.

a-Amido-isosuccinic Acid, CYi. ^.Z{^VL) ^(^^^, is the only amid-de-

rivative prepared from oxysuccinic or isomalic acid. It has been obtained by the
action of hydrocyanic acid and alcoholic ammonia upon pyroracemic acid, CH .
CO.COjH {Berichte, 20, Ref. 507).

3. OXY-PYROTARTARIC ACIDS, CgHgOj = CjHJOH)/^^^^.

(I) a-Oxyglutaric Acid, CH2<^^g^*^^)-^°2^ [Annalen, 208, 66, and

Berichte, 15, IIS7), is obtained by the action of nitrous acid upon glutaminic
acid ; it occurs in molasses. It crystallizes with difficulty, and melts at 72°.
Heated with hydriodic acid it yields glutaric acid (p. 417).

Glutaminic Acid, CS.^(^^^^^^'^-^^ = C^YL^{}>in^)0^, occurs with

aspartic acid in the molasses from beet root, and is formed along with other com-
pounds (p. 366) when albuminoid substances are boiled with dilute sulphuric
acid. It consists of brilliant rhombohedra, soluble in hot water but insoluble in
alcohol and ether. It melts at 140° and suffers partial decomposition. Like all
other amido-acids, it forms salts with acids and bases. Mercuric nitrate throws it
out of aqueous solution as a white precipitate.

Ordinary glutaminic acid is dextro-rotatory. Upon decomposing the albuminoid
conglutin with hydrochloric acid, the ordinary active variety of glutaminic acid is
produced, but if the rupture be brought about by baryta water, an inactive gluta-
minic acid is obtained. The latter is converted into tevorotatory glutaminic acid
by Penicillium glaucum (p. 65) (^Berichte, 17, 388). '

As glutaminic acid is a y-amido-acid it has power to form an amido-anhydride
(a lactam); the resulting (by heating to 190°) Pyroglutaminic Acid, CjH,
NO3, yields pyrrol, C4H5N (Berichte, 15, 1222), when heated further: —

,CO.H CH:CH.

CH^.CH/ yields | )NH.

CH,.CO^

NH CH:CH

Glutamin, C^^{^Yi^<^r-^ k^ 2^ the amide of amido-glutaric acid, corres-
ponding to asparagine, occurs together with this in beet sprouts. It crystallizes in

468 ORGANIC CHEMISTRY.

needles. When digested with baryta water, glutamin changes to amido-glutaric
acid.

(2) j3-Oxyglutaric Acid, CH(OH)/^^2-^q2^, is obtained from a-dicUor-

hydrin (p. 455) by means of potassium cyanide. It forms crystals- which dissolve
easily in water, alcohol and ether, and melt at 135°.

(3) a-Oxypyrotartaric Acid, CH3.C(OH)('^q2^°2^, is produced by the

action of hydrocyanic and hydrochloric acids upon ethyl aceto-acetate, or by oxid-
izing isovaleric acid with nitric acid (p. 347). It forms a thick syrup, which
solidifies in a vacuum and then melts at 108°. Near 200° it decomposes into water
and citraconic anhydride.

(4) Itamalic Acid is only stable in its salts. When free, it decomposes into
water and Paraconic Acid, C5H5O4 [Anna/en, 218, 77) : —

CH,(0H).CH/ yields V ' \CH, •

Itamalic Acid. Paraconic Acid.

Calcium itamalate is obtained by boiling itachlorpyrotartaric acid (p. 418) with
calcium carbonate. Paraconic acid is best prepared by boiling itabrom-pyrotartaric
acid with water. It is very deliquescent and melts at S7-'58°. When boiled with
bases, it forms salts of itamalic acid ; it yields citraconic anhydride when it is
distilled,

(5) y-Oxy-ethyl Malonic Acid, CH2{OH).CH2.CH(C03H)2. Butyro-
lactone carboxylic acid is its lactone acid. This is obtained from brom-ethyl-
malonic acid (melting at 1 17°^— from vinyl malonic acid = Irimethylene dicarboxy-
lie acid) when heated with water : —

yc*c\ TT CH2.CII2.CH.CO2H
CH,Br.CH„.CH( ^X w = I I + HBrj

and when isomeric vinaconic acid (a-trimethylene dicarboxylic acid) is digested
with dilute sulphuric acid (p. 352) [Anna/en, 227, 13).

Heated to 120° it breaks up into carbon dioxide and butyrolactone (p. 362).

(6) Citramalic Acid, C3H5(OH)-Q „^2 jg obtained by the action of zinc

and hydrochloric acid upon chlorcitramalic acid, CjHjClOj (by addition of ClOH
to citraconic acid). Large crystals, melting at 1 19° and decomposing at 130° into
water and citraconic acid.

(7) Ethyl Tartronic Acid, C2H5.C(OH);^^925,is obtained bychlorinating

etbyl malonate, C2Hj.CH(C02H)2, and subsequently saponifying it with baryta
water (p. 409). It melts at 98° and at 180° decomposes into carbon dioxide and
o-oxybutyric acid.

4. Acids, CeHioOs.

(i) Methyl Itamalic Acid, CgHijOj, and Methyl Paraconic Acid,

/CO2H .CO2H

CH3.CH(0H).CH( yields CH3.CH.CH<f

^CH2.C02H I ^CHj

0 CO.

DIATEREBIC ACID. 469

Methyl paraconic acid is produced when acetaldehyde and sodium succinate
are heated with acetic anhydride (p. 463). It crystallizes from benzene in needles
or leaflets. It melts at 79°, and resolidifies at 84°- It unites with bases, in the
cold, to form salts of the formula, CgH^O^Mfe. When it is boiled with bases salts
of methyl itamalic acid are produced : CgHjOgMcj. When distilled methyl para-
conic acid yields valerolactone, ethylidene propionic acid (p. 241), methylitaconic
acid and methyl citraconic acid (p. 463 and Berichte, 24, Ref. 91). . *

(2) Ox3rpropyl Malonic Acid, CgHjoOj, and a-Carbovalerolkctonic
Acid, C,H,0, :—

/CO,H CIIj.CH.CH^.CH.COaH

CH3.CH(OH).CH2.CH( yields | I

^CO^H O CO.

The' second acid has been prepared from allyl malonic acid (p. 430). At 200°
it decomposes into valerolactone and carbon dioxide (p. 363).

(3) Methyl Oxyglutaric Acid, C5H10O5, and 7-Carbovalerolactonic Acid,
C,H,0,:-

.CO2H /COjH

CHj.qOH)/ yields CHj.C/

\CH2.CH2.CO2H I ^CH^.CHj

O CO.

The latter is produced when isocaprolactone (p. 364) is oxidized with nitric
acid (Annalen 208, 62), and by the action of CNK and hydrochloric acid upon
l^vulinic acid (p. 343). It yields deliquescent needles, melting at 68-70°. Salts
of methyl glutaric acid are formed when it is boiled with bases.
5. Acids, CjHijOj.

(i) Ethyl Itamalic Acid, C^Hi^Oj, and Ethyl Paraconic Acid,
C,H,„0, :-

.CO2H /CO'jH

C,H,.CH(OH).CH( yields C^H^.CH.CH/

\cH2.CO2H I ^CH^.

O CO

/3-Caprolactonic acid is obtained from propionic aldehyde and sodium succinate
(p. 463), and crystallizes in needles or leaflets, melting at 85° C. If boiled with
bases it forms salts of ethylparaconic acid with the formula C,Hj gOsMSj- When
distilled it breaks up chiefly into carbon dioxide and caprolactone (p. 364). Iso-
meric hydrosorbic acid is formed at the same time (p. 245) {Berichte, 23, Ref. 93).

(2) Diaterebic Acid, C^M-^^O^, and Terebic Acid, CyHioO^:—

,CO,H

(CH3),C.CH,.CH/ yields (CH3),C.CH2.CH.C02H
I ^CO,H I I

OH 6 CO.

Terebic acid is formed when turpentine oil is oxidized with nitric acid (also
some dimethyl fumaric acid, p. 430) and when teraconic acid (p. 431) is heated
with hydrobromic or sulphuric acid (p. 352). It is sparingly soluble in cold
water, crystallizes in shining prisms, melts at 175° and sublimes even below this
temperature. It is a monobasic acid, and with carbonates yields the salts
C,HgMeO^, which are generally easily soluble; stronger bases will change these
compounds into salts of dibasic-diaterebic acid, C^IA^^yi&f)^. When terebic

47° ORGANIC CHEMISTRY.

acid is distilled it forms carbon dioxide and pyroterebic acid (isocaprolactone is
produced at the same time, p. 364). When sodium acts on the ethyl salt it forms
ethyl teraconate (431) (Annaltn, 226, 363).

(3) Carbocaprolactonic Acid, CHj.CH.CHj.CH.CHj.COjH, from allyl

i-i do

sucanic acid (p. 430), melts at 69°, and distils with scarc^y any decomposition
at 260°/

6. Acids, CjHi^Os.

(i) Propylitamalic Acid, CgHj^Oj, and Propylparaconic Acid,
CgHiaO^:—

-COjH .COjH

C3H,.CH(0H).CH( yields CjH-.CH.CH^

^CH,.COH, I ^CH,

O CO

Propylparaconic acid is obtained from butyraldehyde and succinic acid. It melts
at 73-5°. On boiling with bases it forms salts of propylitamalic acid, CjHuOgM^j.
Heptolactone, heptylenic acid, CjHjjOj, and propylitaconic acid,CjHj20^ (Be-
richte, 20, 3180), are produced by the distillation of propylparaconic acid.

(2) Isopropylitamalic and Isopropylparaconic Acids are similarly obtained
from isobutyraldehyde and succinic acid. The second melts at 69°, and when dis-
tilled decomposes into isoheptolactone and isoheptylenic acid {Berichte, 23, Ref.

94)-

(3) DiaterpenylieAcid,CgHi^05. Itslactone, Terpenylic Acid, CjHjjO^,
is obtained by oxidizing turpentine oil and various terpenes with potassium chlo-
rate and sulphuric acid (Berichte, 18, 3207). It crystallizes in large leaflets with one
molecule of water, and melts when anhydrous at 90°. It unites with carbonates
and forms salts of terpenylic acid, CjHjjMeO^. Caustic alkalies convert these
into salts of dibasic diaterpenylic acid, CgHj2Mej05. When distilled, terpenylic
acid decomposes into carbon dioxide and teracrylic acid, CjHjjOs (p- 241).

UNSATURATED OXYDICARBOXYLIC ACIDS, C^^^-Si^.
The supposed Oxymaleic Acid, 0^11405 = C2H(OH)/~92H ^^^^ \)xom-

malelc acid, appears not to exist (Annalen, 227, 233).

Oxyitaconic Acid, C5H5O5, is only stable in its salts. Its lactone acid — mono,
basic Aconic Acid, CjH^Oi — results from boiling monobromitaconic acid (from
itabrompyrotartaric acid, p. 418), with water. Soluble rhombic crystals, melting
at 164°. It is not capable of combining with bromine [Annalen, 216, 91).

Oxycitraconic Acid, C5H5O5, is obtained from chlorcitramalic acid (p. 468)
by means of baryta water. It forms readily soluble prisms. It does not unite with
bromine or nascent hydrogen, but when heated to 1 10° with hydriodic acid, it is
converted into citramalic acid, C^HgOj. When boiled with water, it decomposes
into 2CO2 ^"'^ propionic aldehyde {Annalen, 227, 237).

Oxyhydromuconic Acid, C^HjOg. Its lactone-anhydride, monobasic Mu-
colactonic Acid, or Muconic Acid, CgHg04, is obtained by heating dibrom-
adipic acid, CgHjBrjO^, (from hydromuconic acid, p. 430), with silver oxide.
Large, readily soluble crystals, which melt near 100°. It decomposes into carbon
dioxide and acetic and succinic acids when boiled with baryta water.

TRIBASIC ACIDS. 47 1

TRIBASIC ACIDS, C^H^^-^Oe.

Formyl Tricarboxylic Acid, Methenyl Tricarboxylic Acid, CH(C02H)3
= C^Hfig, is decomposed into carbon dioxide and malonic acid, CH2(C02H)2,
when it is freed from its esters by alkalies or acids (p. 401). The triethyl ester,
CH(C02.C2H5)3, is obtained from sodium malonic ester, CHNa(COj.C2H5)2,
and ethyl chlorcarbonate [BericAte, 21, Ref. 531); it is crystalline, melts at 29°,
and boils at 253°- Sodium alcoholate decomposes it.

CHj.COjH

Ethenyl Tricarboxylic Acid, "j = CgH-O,, is obtained by the

CH(C02H)2
saponification of ethyl acetylene tetracarboxylate, C2H2(C02.C2Hg)4, and firom
esters of cyansuccinic acid, C2H3(CN)(C02R)2. It melts at 159° and is decom-
posed into carbon dioxide and succinic acid. The ethyl ester, C5H3{C2H5)30j,
is obtained from sodium ethyl malonate and the ester of chloracetic acid. It boils
at 278°. Chlorine converts it into Chlorethenyl Tricarboxylic Ester, C2H2CI
(COj.CjHj),. This boils at 290°, and when heated with hydrochloric acid,
yields carbon dioxide, hydrochloric acid, alcohol and fumaric acid ; when saponi-
fied with alkalies, carbon dioxide and malic acid are the products {Annalen, 214,

44)-

Higher tricarboxylic acids have been variously produced by analogous methods :

(1) By the action of the esters of haloid fatty acids upon the sod-malonic esters,
CHNa.(C02R)2, and the sod-alkyl-malonic esters, R.CNa(C02R)2.

(2) By the action of alkyl haloids upon esters of ethenyl tricarboxylic esters.
Of the resulting isomeric acids, those obtained by the second method are desig-
nated ^-derivatives of ethane- or ethenyl-tricarboxylic acid (see above).

Many tri- and poly • carboxylic acids have been prepared. They lose carbon
dioxide, and yield the corresponding mono- and dialkylic succinic acids (p. 400)
(Annalen, 214, 58; Berichte, 16, 333; 23, 633).

CH3.CH.CO2H

a-Methyl Ethenyl Tricarboxylic Acid, CjHjO, = I ,

(!:h(C02H)2

a-propenyl tricarboxylic acid (isomeric with tricarballylic acid). Its ethyl ester,
C8H50g(C2H5)3,is prepared from ethyl malonate and the ester of a-brompropio-
nic acid. It boils at 270°.

The free acid melts at 140°, and.breaks down into carbon dioxide and methyl
succinic acid.

CH2.CO2H
fl-Methyl Ethenyl Tricarboxylic Acid, | ,/3 propenyl tricar-

CH3.C(C02H)2
boxylic acid. Its methyl ester is formed when chloracetic ester acts upon methyl
malonic ester, or methyl iodide upon ethenyl tricarboxylic ester. It boils at 273°.
It yields methyl succinic acid when saponified with sulphuric acid.

CjHg.CH.COjH
a-Ethyl Ethenyl Tricarboxylic Acid, ) , a-butane tricar-

CH(C02H)2
boxylic acid. The ethyl ester is obtained from malonic ester and a-brombutyric
ester. It boils at 278°. It passes, by saponification, into ethyl succinic acid.

CHj.COjH
3-Ethyl Ethenyl Tricarboxylic Acid, I , /3-butane tricar-

CjH5.C(C02H)2
boxylic acid. The ethyl ester is formed in the action of chloracetic ester upon
ethyl malonate, as well as that of ethyl iodide upon ethenyl tricarboxylic ester. It
boils at 281°. It forms ethyl succinic acid when saponified.

472 ORGANIC CHEMISTRY.

(CH3)2.C.C02H
a-Dimethyl Ethenyl Tricarboxylic Acid, | , isobutylene

CH(COjH)
tricarboxylic acid. Its ethyl ester is obtained from a-bromisobutyric ester, (CH3)j.
CBr.COj.CjHj, and malonic ester. It boils at 277° C. It yields unsymmetrical
dimethyl succinic acid (p. 420) when saponified.

CHj.CH.COjH
aj} Dimethyl Ethenyl Tricarboxylic Acid, I • , butane tricar-

CH3.t(C0,H),
boxylic acid. Its ethyl ester is made from a-brompropionic ester and methyl
malonic ester, as well as by the action of methj^ iodide upon a- propenyl tricarboxy-
lic ester. It boils at 279°, and yields both dimethyl succinic acids (p. 420) when
saponified.

a/3-Methyl-ethyl-, a;3-diethyl-, etc., ethenyl tricarboxylic esters, (RR'')C2Hj
(C02R)3, have been produced in an analogous manner. They have also yielded
the corresponding alkylic succinic acids when saponified (p. 400 and Berichte, 23,
647).

Tricarballylic Acid, CsHsOe = C3H5(CO,H)3, is obtained :
(i) by heating tribromallyl with potassium cyanide and decompos-
ing the tricyanide with potash : —

CH,Br CH,.CO,H

i:

HBr yields CH.CO^H;

CHjBr CHj.COjH

(2) by oxidizing diallyl acetic acid (p. 245) ; (3) by acting upqn
ethyl aceto-succinate with sodium and the ester of chloracetic acid,
then saponifying the aceto-tricarballylic ester (p. 342) ; (4) by the
decomposition of a-propylene-tetracarboxylic acid ; (5) by the ac-
tion of nascent hydrogen upon aconitic acid, CsHsOg {Berichte, 22,
2921), and by the reduction of citric acid with hydriodic acid; also
from dichlorglycide, C3H4CI2, and chlorcrotonic ester, C^HjClOj.
C2H5, by the action of potassium cyanide. The acid occurs in un-
ripe beets, and also in the deposit in the vacuum pans used in beet-
sugar works. It crystallizes in rhombic prisms, which dissolve easily
in water, alcohol and ether, and melt at 158° (166°).

The iz'/pf?- jo//, CjHgOjAgg, is insoluble in water. Calcium tricarballylate
(C5H505)2Ca3 -|- 4H2O, is a powder that dissolves with difficulty. The trime-
thyl ester, C5H508(CH3)3, boils at 150°, under a pressure of 13 mm. The chlor-
ide ol tricarballylic acid, €3115(00.01)3, results from the action of phosphorus
pentachloride. The triamide, CgH5(CO.NH2)3, melts at 206°.

Aconitic Acid, CeHgOe ^ CsH3(C02H)3* belongs to the class
of unsaturated tricarboxylic acids.

V —

* It is isomeric with trimethylene tricarboxylic acid (see this).

TETRAHYDRIC ALCOHOLS. 473

It occurs in different plants, for example, in Aconitum Napellus,
in Equisetum fluviatile, in sugar cane and in beet roots. It is ob-
tained by heating citric acid alone or with concentrated hydrochloric
acid : —

CHj.COjH CH.COjH

C(0H).C02H = C.COjH + HjO.

CH2.CO2H CH^.COjH

Citric Acid. , Aconitic Acid.

Its formation, when acetylene dicarboxylic acid is treated with
alcoholic potash, is rather peculiar {Berichte, 22, 3055).

Preparation. — Citric acid is rapidly heated in a flask until the formation of white
vapors ceases and oily streaks line the neck. The residue is taken up in a little
water, evaporated to crystallization, and the crystalline deposit extracted with ether,
which will dissolve only aconitic acid. To obtain the latter pure, decompose the
lead salt with hydrogen sulphide {Berichte,^, 1751).

A beUer method consists in boiling citric acid (100 grs.) with water (50 grs.)
and sulphuric acid (100 grs.) for a period of 4-6 hours {Berichte, 20, Ref. 254).

Aconitic acid crystallizes in small plates, which dissolve readily in
alcohol, ether and water. It melts at 186-187° ^'^^ decomposes into
carbon dioxide and itaconic acid. Nascent hydrogen converts it
into tricarballylic acid, CsHeOe -|- Ha = CsHgOs.

It gives rise to three series of salts. The tertiary lead salt is insoluble in hot
water. The calcium salt (CgHjO^ j^Caj -f- 6H2O, dissolves with difficuliy. The
esters of aconitic acid are obtained by conducting hydrochloric acid gas into alco-
holic solutions of the acid {Berichte, 21, 670) ; as well as by heating aceto-citric
esters to 250-280°. The trimethyl ester, C5H30j{CH3)3, is a yellow oil. It boils
at 200°.

Concentrated ammonia converts the esters into aconitic triamide, C3Hj(CO NH 2)3.
A yellow, crystalline powder, soluble in water. Acids change it to citrazic acid
(== dioxypyridine carboxylic acid) {Berichte, 22, 1078, 3054 ; 23, 831).

Isomeric Pseudo-aconilic Acid, CjHgOj, results upon heating a-propylene tetra.
carboxylic acid (p. 482) to 200°, when it splits off carbon dioxide. It melts at
145-150° C.

TETRAVALENT COMPOUNDS,

TETRAHYDRIC ALCOHOLS.

Ortho-carbonic Ester, C{O.Cfi^)^{oi Basset), may be regarded as the ether ot
the tetrahydric alcohol or normal carbonic acid, C(0H)4. It is produced when
sodium ethylate acts on chloropicrin : —

CCl3(N02) + 4C2H5.0Na. = Ci^.C^YL^^^ + sNaCl + NO^Na.

It is a liquid with an ethereal odor, and boils at 158-159°. When heated with
ammonia it yields guauidine.
40

474 ORGANIC CHEMISTRY.

The propyl ester, Q.[O.Q,^,,')^^, boils at 224, the isobutyl ester at 250°, and it
seems the methyl ester cannot be prepared (Annalen, 205, 254).

Erythrol, Erythrite, QHioO^ = CH,(OH).CH(OH).CH
(0H).CH2.0H, Erythroglucin or Phycite, occurs free in the
alga Protococcus vulgaris. It exists as erythrin (orsellinate of
erythrite) in many lichens and some algse, especially in Roccella
Montagnei, and is obtained from these by saponification with caus-
tic soda or milk of lime : —

"4^6 1

(oSh,03),+ 2^2° ^ C,H,(OH), + 2C3H,0,.

Erythrin. Erythrol. Orsellinic Acid.

Erythrol forms large quadratic crystals, which dissolve readily in
water, with difficulty in alcohol, and are insoluble in ether. Like
all polyhydric alcohols erythrol possesses a sweet taste. It melts at
126° and boils at 330° {Berichte, 17, 873). When heated with
hydriodic acid it is reduced to secondary butyl iodide : —

C,H,(OH), + 7HI = C.HJ + 4H,0 + 3I..

By carefully oxidizing erythrol with dilute nitric acid an aldehyde body is ob-
tained, which combines with two molecules of phenylhydrazine to form phenyl
erythrosazone, C4H502(N2H.C8H5)j, melting at 167° {Berichte, 20, IO90).
More intense oxidation with nitric acid produces inactive tartaric acid.

Erythrol yields esters with acids. The nitric acid ester, the so-called nitroery-
thrite, C^^iOMO^^, is obtained by dissolving erythrol in fuming nitric acid;
it separates in brilliant plates, melting at 61°. It burns with a bright flame and
explodes violently when struck.

Concentrated hydrochloric acid converts Erythrol vcAo the dichlorhydrin, C^Hg
(OH)2Cl2 (melting at 125°). Caustic potash converts this into the dioxide, the
so-called Erythrol ether, CHj.CH.CH.CH^. This is a pungent-smelling liquid

of sp. gr. I.I 13 at 18°; boils at 138° and volatilizes with ether vapors. In its
reactions it is perfectly similar to the alkylen oxides (p. 300) . It combines gradu-
ally with water, forming erythrol, with 2HCI yielding dichlorhydrin, with 2CNH
to form the nitrile of dioxyadipic acid, etc. {Berichte, 17, 1091).

MONOBASIC ACIDS.

Erythritic Acid, C^HjOj = CgH^ { CO H ' erythroglucic acid, trioxybutyric

acid, is produced in the oxidation of an aqueous erythrol solution with platinum
sponge. It forms a deliquescent crystalline mass. The same acid is probably
formed on oxidizing Isevulose with mercuric oxide or bromine water (Berichte, 19,
•390). It also results from the oxidation of mannitol with potassium permanga-
nate [Berichte, 19, 468).

Tartaric Acid, CiHgOg = 1 , or Dioxysuccinic Acid.

CI

TARTARIC ACID. 475

DIBASIC ACIDS.

Dioxymalonic Acid, CsH^Og = C{OH) /^q^^, obtained from dibrom-
malonic acid, is identical with mesoxalic acid (p. 434).
CH(OH)— CO2H

i;H(OH)— co^h'

Several modifications of this acid are known ; all possess the
same structure {Berichfe, 21, 519) and can be converted into each
other. They are the ordinary or dextro-tartaric acid, Isevo-tartaric
acid, racemic acid and inactive mesotartaric acid. They are chiefly
distinguished by their different optical rotatory power, but all, how-
ever, yield the same products of transposition, hence they are
viewed as physical isomerides (p. 49).

The dififerences in these acids, according to the Le Bel-van't Hoff theory, are
attributable to the presence of two asymmetric carbon atoms in dioxysuccinic
acid (p. 63) :—

II H

i I

HO— C C— OH.

I I

CO2H COjH

The two intermediate carbon tetrahedra, having a common axis and joined by
one summit, have the three different groups arranged right or left. This would
result in a dextro- and Isevo-rotatory tartaric acid. If, however, the three side
groups are arranged in opposite directions, their influence will cease, and the pro-
duct will be an inactive tartaric acid. This cannot be resolved ; it is known as
the meso- or anti-form. Again, the dextro- and laevo-modifications can unite,
producing an optically inactive modification, that can be resolved into its two
active components. This is the para-iorm. It is represented by racemic acid
(p. 478). Consequently, dioxysuccinic acid can exist according to theory in three
or four different modifications. This is confirmed, too, by inany facts (Berichte,
21, 2106; 22, 1813).

Dioxysuccinic acid is synthetically prepared by boiling dibrom-
succinic acid with moist silver oxide : —

CHBr.COjH CH(OH).C02H

I + 2AgOH = I + 2AgBr.

CHBr.CO^H CH(0H).C02H

The product in this reaction consists of inactive tartaric acid and
racemic acid. Only the latter is formed when hydrocyanic acid and
hydrochloric acid (p. 324) act upon glyoxal : —

CHO CH(0H).C02H

-f 2CNH -f 4H„0 = I + 2NH3.

HO CH(0H).C02H

i

47^ ORGANIC CHEMISTRY.

Racemic acid is also produced when fumaric acid is oxidized with
potassium permanganate, while maleic acid, by the same treatment,
yields inactive tartaric acid. Mannitol, when oxidized with nitric
acid, yields racemic acid, and sorbine yields inactive tartaric acid.

Racemic acid can yield dextro- and laevo-tartaric acid (p. 478).
Heat converts ordinary dextro-tartaric acid and also racemic acid
into inactive tartaric acid ; conversely, the latter can change to
racemic acid by heat (p. 478).

All the tartaric acids, when heated with hydriodic acid, sustain a
reduction of the OH-groups and change first to malic and then into
succinic acid (p. 410) ; in this case active tartaric acid yields malic
acid, the inactive tartaric, however, inactive malic acid — whereas
succinic acid is always inactive (p. 64).

I. Dextro-rotatory or Ordinary Tartaric Acid {Acidum
tartaricuni) is widely distributed in the vegetable world, and occurs
principally in the juice of the grape, from which it deposits after
fermentation in the form of acid potassium tartrate (argol). It
results on oxidizing saccharic acid and milk sugar with nitric acid.

Preparation. — Crude argol is purified by crystallization and boiled with pul-
verized chalk and water ; this causes it to separate into easily soluble, neutral potas-
sium tartrate and neutral calcium tartrate, which separates as an insoluble powder.
Calcium chloride precipitates all the tartaric acid as neutral calcium salt from the
filtered solution containing neutral potassium tartrate. The calcium salt is decom-
posed by dilute sulphuric acid, the gypsum filtered ofif, and the solution concentrated
by evaporation.

Common tartaric acid crystallizes in large monoclinic prisms,
which dissolve readily in water and alcohol, but not in ether. Its
solution turns the ray of polarized light to the right. It melts at
167-170° {Berichte, 22, 1814), when rapidly heated, and in so
doing is converted into an amorphous modification, called metatar-
taric acid, which crystallizes again from water as tartaric acid.
Heated for some time at 150° water escapes, and we get the anhy-
drides (p. 351) : Ditartaric acid (or tartralic acid), CgHioOn, iar-
trelic acid and tartaric anhydride, C4H4O5. The latter is a white
powder which reverts to tartaric acid when boiled with water. Py-
roracemic and pyrotartaric acids are products of its dry distillation.

When gradually oxidized tartaric acid becomes oxymalonic acid
(p. 463) ; stronger oxidizing agents decompose it into carbon
dioxide and formic acid.

Tartrates.— T^xz acid forms salts which contain usually one and two equivalents
of metal; there are, however, some with four equivalents of metal; here four hy-
drogen atoms (two of the CO^H groups and two of the OH groups) are replaced.
The polyvalent acids form such salts with less.basic metals, like lead and tin.

The neutral potassium salt, C^H^KjOg + ^H^O, is readily soluble in water;
from it acids precipitate the salt C4H5KO5, which is not very soluble in water, and
constitutes natural tartar [Cremor tartari).

ljevo-tartaric acid. 477

Potassium- Sodium Tartrate, C^H^KNaOj + 4H2O {Seigneitis salt), is made
by saturating cream of tartar with a sodium-carbonate solution. It crystallizes in
large prisms witli hemihedral faces. The calcium ,salt, C^H^CaO, + 4H2O, is
precipitated from solutions of neutral tartrates, by calcium chloride, as an insoluble,
crystalline powder. It dissolves in acids and alkalies, and is reprecipitated on
boiling — a reaction serving to distinguish tartaric from other acids. Consult Anna-
len, 226, 161, upon the calcium salts of the different tartaric acids.

The neutral lead salt, C^H^PbOj, is a curdy precipitate. On boiling its ammo-
nia solution a basic salt, C^HjPbjOg, is deposited; in this the hydrogen atoms of
the four OH groups of tartaric acid ar« replaced by lead.

Potassio-aniimonious Tartrate, C4H^(SbO)KOj + ^HjO, tartar emetic.
In this an atom of hydrogen is replaced by antimonyl (SbO) [Berickte, 13, 1787).
It is prepared by boiling cream of tartar with antimony oxide and water. It crys-
tallizes in rhombic octahedrons, which slowly lose their water of crystallization on
exposure and fall to a powder. It is soluble in 14 parts water at 10°. Its solu-
tion possesses an unpleasant, metallic taste, and acts as a. sudorific and emetic.
When the salt is heated to 200°, i molecule of water escapes and we get the basic

///
salt, C^HjSbKOg, corresponding to basic lead tartrate. Consult Berichte, 16,

2379-

To obtain the esters of tartaric acid, CjHj02(C02R)2, dissolve the acid in me-
thyl or ethyl alcohol, conduct hydrochloric-acid gas through the solution, and distil
the liquid under diminished pressure, repeating the process (Berichte, 13, 1175).
The esters of the other tartaric acids are similarly obtained [Berichte, 18, 1397).
The dimethyl ester, C^H40g(CH3)2, is crystalline, melts at 48°, and boils at 280°.
The diethyl ester, Cfifi^^Cfi^^^, is a liquid, also boiling at 280°. It is dextro-
rotatory. The dipropyl ester, boils at 300° C.

When acetyl chloride acts upon the diethyl ester, the hydrogen of the alcoholic
hydroxyl groups is replaced and we obtain acetyl and diethyl diacetyl tartaric esters,
C2H2{O.CjH30)2(C02.CjH5)2; the first is a liquid ; the second melts at 67°,
and boils without decomposition at 290°.

The.nitro-group, NO^, can effect the same kind of substitution as noted above
(p. 302). By dissolving pulverized tartaric acid in concentrated nitric acid and

adding sulphuric acid, so-called Nitro-tartaric Acid, C^J^^O.^^{q^y{^

results. This is a gummy mass, which on drying becomes white and shining. It
is soluble in water. When its solution is heated tartronic acid is produced. It
slowly decomposes into tetra-oxysuccinic acid.

Tartramic Acid,C^^(pYL)yf^Q ^ 2_ Its ammonium salt is obtained by

acting on tartaric anhydride, C^H^Oj, with ammonia. From a solution of this
salt calcium chloride precipitates calcium tartramate. The acid can be obtained
in large crystals from the latter.

Tartramide,C^^^{0\V)^<^^^-^^^,\s produced by the action of ammonia
upon diethyl tartrate. ^ ' ^

2. Lxvo- Tartaric Acid is very similar to tlie dextro-variety, also
melts at 167-170°, and only differs from it in deviating the ray of
polarized light to the left. Their salts are very similar, and usually
isomorphous, but those of the Isevo-acid exhibit opposite hemihedral
faces. On mixing the two acids, we get the optically inactive ra-
cemic acid, which in turn may be separated into the two original
acids (see below).

478 ORGANIC CHEMISTRY.

The esters of Isevo-tartaric acid are obtained in the same manner as those of
the dextro-acid (see above). The dimethyl ester, C^H^Og(CH5)2, is similar to
that of the latter. It melts at 48°, and boils at the same temperature as the
dextro-ester. It is, however, Isevo-rotatory.

3. Racemic Acid\% sometimes found in conjunction with tartaric
acid in the juice of the grape, and is obtained from the mother
liquor in crystallizing cream of tartar.

The mother liquor is boiled and saturated with chalk; the calcium salt which
separates is decomposed with sulphuric acid and the filtrate evaporated to crystal-
lization. As the crystals of racemic acid effloresce on exposure to the air, they can
be readily separated mechanically from ordinary tartaric acid.

Racemic acid appears in the oxidation of mannitol, dulcitol and
mucic acid with nitric acid. It is synthetically obtained from
glyoxal by means of prussic and hydrochloric acids, and (together
with meso-tartaric acid) from dibromsuccinic acid, by the action of
silver oxide (p. 475) ; in addition by heating desoxalic acid or its
ester (p. 485) with water or dilute acids to 100° : — CsHgOs ^ CiHgOt
+ CO2. An interesting method of preparing it is that of oxidizing
fumaric acid with potassium permanganate (p. 426)".

Racemic acid is most readily made by heating ordinary tartaric
acid with water {^ part) to 175°. The product consists of inac-
tive tartaric acid and racemic acid. These can be separated very
easily by crystallization.

Racemic acid crystallizes in prisms having a molecule of water.
These slowly effloresce in dry air, and at 100° lose water. It is
less soluble (i part in 5.8 parts at 15°) in water than the tartaric
acid, and has no effect on polarized light. It loses its crystal water
when heated to 110°. In the anhydrous condition it melts at 205-
206°. It foams at the same time. Its salts closely resemble those
of tartaric acid, but do not show hemihedral faces. The acid
potassium salt is appreciably more soluble than cream of tartar.
The calcium salt dissolves with more difficulty, and is even precipi-
tated by the acid from solutions of calcium chloride and gypsum.
Acetic acid and ammonium chloride do not dissolve it.

The acid is composed of dextro- and Isevo-tartaric acids. It is
most readily converted into these through the sodium ammonium
salt, C4H4Na(NH4)06 + 4H2O. On saturating acid sodium race-
mate with ammonia and allowing it to crystallize, large rhombic
crystals form. Some of these show right, others left hemihedral
faces. Removing the similar forms, we discover that the former
possess right-rotatory power and yield common tartaric acid, whereas
the latter yield the Isvo-acid. The separation is easier if we project
crystal fragments into a supersaturated mixture of the acids. In
this case only crystals of the forms introduced will separate. By

DIBASIC ACIDS. 479

mixing dextro- and Isevo-acid, we again obtain racemic acid. Peni-
cillium glaucum destroys the dextro-tartaric acid, and thus decom-
poses the racemic acid.

The methods employed for the preparation of the esters of ordinary tartaric
acid (p. 477) will serve for the production of those of racemic acid. The dime-
thyl ester, 0^11405(0113)2, consisting of monoclinic prisms, melts at 85° and
boils at 282°. It is inactive. It can be made with exactly the same properties by
fusing together the dimethyl ester of dextro- and Isevotartaric acids. In vapor
form the ester of racemic acid has the simple formula given above ; hence, in this
condition it consists of the dimethyl ester of the dextro- and Isevo-tartaric acids,
and upon cooling these reunite to the dimethyl ester of racemic acid (Berichte,
18, 1397).. The dimethyl-diethyl racemic ester deports itself similarly [Berichte,
21, Ref. 643.)

4. Inactive Tartaric Acid, Mesotartaric Acid, Antitartaric Acid,
is obtained when sorbine and erythrol are oxidized with nitric acid,
or when dibromsuccinic acid is treated with silver oxide (p. 475)
and maleic acid with potassium permanganate (p. 426). It is most
readily prepared by heating common tartaric acid with water to 65°
for two days. The acid potassium salt affords a means of separating
it from unaltered acid and the little racemic acid produced at the
same time. At 175° more racemic acid is obtained. The latter
acid, when heated alone or with water to 170-180°, may be changed
to the inactive acid. Conversely, when the inactive acid is raised
to the same temperature with water, it is transformed into racemic
acid ; a state of equilibrium occurs between the two acids in solu-
tion ; this can be overcome by removing one of the acids and by
repeated heatings (Jungfleisch).

Mesotartaric acid resembles racemic acid very much. It is more
soluble in water (i part in 0.8 parts at 15°). It crystallizes in long
prisms containing one molecule of water. These effloresce in the
dessicator, lose all their water at 110°, and then melt at 143°. The
acid is optically inactive and cannot be directly transformed into
the active tartaric acids. Its salts and esters also distinguish it from
racemic acid {Berichte, 17, 141 2; 21, 519).

CH3.C(OH).C02H
Dimethyl Racemic Acid, C.H,„08 = I , is a- homologue of

CH3.C(OH).C02H
racemic acid. It is produced when hydrocyanic and hydrochloric acids act upon
diacetyl, CH3.CO.CO.CH3 (p. 326). This procedure is analogous to tha,t by which
glyoxal yields racemic acid. The acid contains one molecule of crystal water and
when anhydrous, melts at 179° (Berichte, 22, Ref. 137).

48o ORGANIC CHEMISTRY.

TRIBASIC ACIDS.

The supposed Carboxytarlronic Acid,C^^O^ = C(OH)(C02H)3, has been
proved to be a dibasic acid — Tetraoxysuccinic Acid, Q.^(OYi>j^.(y,0^')^ =
C^H.O, (p. 490-

Citric Acid, CeHsO, = C3H,(OH)(CO,H)3, oxytricarballylic
acid {Acidum citricum), occurs free in lemons, in black currants, in
bilberry, in beets and in other acid fruits. It is obtained from
lemon juice for commercial purposes.

Lemon juice is boiled (to coagulate albuminoid substances), 61tered and satu-
rated with calcium carbonate and slacked lime. The calcium salt which separates
is decomposed with sulphuric acid and the filtrate concentrated.

The acid can be prepared synthetically from /9-dichloracetone ; this
is accomplished by first acting on the latter compound with prussic
acid and hydrochloric acid, when we get dichloroxyisobutyric acid
(p. 363), which is then treated with KCN and a cyanide obtained.
The latter is saponified with hydrochloric acid : —

CHjCl CH3CI CHj.CN CHj.COjH

CO C(0H).C02H C(0H).C02H C(OH).COjH.

CHjCl CHjCl CHj.CN CHj.COjH

|3-Dichloracetone. Dichloroxyisobutyric Dicyanoxyisobutyric Citric Acid.

Acid. Acid.

Citric acid is also obtained by the action of prussic and hydro-
chloric acids upon acetone dicarboxylic acid, and from cyanacetic
ester, CN.CHj.CO.CHj.COjR, by the same reagents (BerjcAU, 22,
Ref. 256).

Citric acid crystallizes with one molecule of water in large rhom-
bic prisms, which melt at 100°, lose their crystal water at 130° and
then melt at 153°. It dissolves in 4 parts of water of ordinary
temperatures, readily in alcohol and with difficulty in ether. The
aqueous solution is not precipitated by milk of lime when cold, but
on boiling the tertiary calcium salt separates. This is insoluble,
even in potash (.see Tartaric Acid). When heated to 175° citric
acid decomposes into water and aconitic aci'd (p. 472). It breaks
up into acetic and oxalic acids when fused with caustic potash, and
by oxidation with nitric acid. Acetone dicarboxylic acid (p. 435)
is produced when citric acid is digested with concentrated sulphuric
acid.

Being a tribasic acid it forms three series of salts. Tertiary potassium citrate,
C5H5K3O7 + HjO, is made by saturating the acid; it consists of deliquescent
needles. The secondary salt, CjIi^KjO,, is amorphous; the primary salt, CjHj
KOj -{- 2HjO, forms large prisms. All three dissolve readily in water. Ter-

TETRABASIC ACIDS. 48 1

tiary calcium citrate, (CjHsOjj^Ca, + 4H2O (p. 480), is a crystalline powder.
The silver salt, CjHjAgjO,, is a white precipitate which turns black on ex-
posure.

The neutral esters are produced by conducting hydrochloric acid into hot alco-
holic solutions of the acid. The trimethyl ester, C3H4(OH).{C02.CH,)3, is
crystalline, melts at 79° and distils near 285°, decomposing partially at the same
time into aconitic ester and water (Berichte, 17, 2683). The triethyl ester,
C,H4(0H).(C02. 02115)3, boils near 280° (Berichte, 13, 1953).

The action of acetyl chloride on the esters replaces the alcoholic hydrogen.
The acetocompound, C3H4(O.CjH30)(C02.C2H,)3, boils at 280°. It breaks
down into acetic acid and aconitic ester, when it is distilled. Nitric acid, too,
substitutes the nitro-group for the hydrogen of hydroxyl in the esters.

Citramide, C3H4(OH)(CO.NH2) j, is formed by the action of NH3 upon ethyl
citrate. The mono- and diamine acids are formed at the same time {Berichte, 17,
2682). Citramide is crystalline, dissolves readily in hot water and blackens when
heated above 200° C. When digested with hydrochloric or sulphuric acid it is
condensed to citrazinic acid (dipxypyridine carboxylic acid) (Berichte, 23, 831).

TETRABASIC ACIDS.

CHCCOa.H)^

Acetylene Tetracarboxylic Acid, | . Its ester, C^Hj

CH(C02.H)2
(02115)408, is obtained from sodium malonic ester, 0HNa(C02.C2H5)2, by
the action of chlormalonic ester, CHC^COj. 02115)2, or from sodium malonic
ester and iodine {Berichte, 17, 2781). It consists of long, shining needles, which
melt at 76° and boil at 305°- Aqueous potash converts it into ethenyl tricarboxylic
acid and COj (p. 471).

Acetylene tetracarboxylic ester and sodium ethylate yield a disodium com-
pound which unites with o-xylylene bromide, C8H4(CH2Br)2, to form tetrahydro-
naphthalene tetracarboxylic ester {Berichte, 17, 449).

See Berichte, ai, 2085, upon diethyl-ethenyl tetracarboxylic acid.

Acids, CjHjO, = C^Yi.^{CO^W)^.

Sodium and ethyl chloracetate change ethenyl tricarboxylic ester into the ester

of a-Propane-Tetracarboxylic Acid, C(C02H)2(' q^^qq^jj, which boils

with slight decomposition at 295°. The free acid is obtained by saponifying the
ester. It melts at 151° and decomposes into carbon dioxide and tricarballylic
acid. ,

;3-Propane Tetracarboxylic Acid, CH2(^^|[][|co'h)'- ^'^ tetraethyl ester
is obtained by the condensation of formic aldehyde, CHjO, or methylene iodide
{Berichte, 22, 3294) with two molecules of malonic ester, and by the action of
zinc dust and acetic acid upon ^-propylene tetracarboxylic acid {Berichte, 23,
Ref. 240). It is a thick oil, boiling at 240° under 100 mm. pressure. The free acid
decomposes into 2CO2 and glutaric acid, 0H2.(CH2.CO2H)2 (p. 417)- Its
disodium compound and alkyl iodides yield dialkyl derivatives. Bromine converts
it into ;8 trimethylene tetracarboxylic ester.

Acids, CjHioOg = C'^^{CO^Yi)^.

(I) Ethidene Dimalonic Acid, CH3.Ch/^|[^|^°^H)2 ^g ethyl ester is
produced by the union of ethidene malonic ester (p. 428) and malonic ester. It

482 ORGANIC CHEMISTRY.

is a thick oil, boiling at 210° under 20 mm. pressure. The free acid separates
into aCO, and ethidene diacetic acid (p. 420) when distilled.

CHj.qCO.H),

(2) Dimethyl-Acetylene Tetracarboxyllc Acid, | . The

CHj.qCO.H)^
tetraethyl ester is produced by the introduction 'of 2 CH 3 -groups into acetylene
tetracarboxylic ester; also from sodium-methyl malonic ester, CH3.CNa(C02R)2,
by the action of iodine {Berickie, 18, 1202). The free acid splits off COj afld
yields symmetrical dimethyl succinic acid (p. 420).

CaHs.qCOjH)^

(3) Ethyl-Acetylene Tetracarboxylic Ester, I . Its ethyl

(!;H(C0,H),
ester is obtained from ethyl malonic ester and chlormalonic ester. It is a thick
oil (Berichte, 17, 2785).

CHj.CH(COjH)2

(4) Butane Tetracarboxylic Acid, | . The methyl ester

CH,.CH(CO,H),
is formed together with a-triinethylene dicarboxylic ester when ethylene bromide
acts upon sodium malonic ester (Berichte, ig, 2038) :

CHjBr CHj.CH(C02R)2

I + 2CHNa(C02R)2 = | + 2Na,Br.

CHjBr CH2.CH(C02R)2

Tetramethylene tetracarboxylic ester is produced when bromine acts upon its
disodium compound.

Acids, CgHijOj.

Pentane-Tetracarboxylic Acid, CH2('^|[][2-^^|^q2^K The ethyl ester

is formed, together with tetramethylene dicarboxylic ester (see this) in the action of
trimethylene bromide upon two molecules of sodium malonic ester (Berichte, 18,
3249). Its disodium compound, when acted upon by bromine, yields penta-
methylene-tetracarboxylic ester.

UNSATURATED TETRACARBOXYLIC ACIDS.

C(CO,H),
Dicarbon-Tetracarboxylic Acid, || . Its tetra-ethyl ester is ob-

C(CO,H), , , . ,

tained by letting sodium ethylate act upon chlormalonic ester, and by the action of
iodine upon disodium malonic ester (Berichte, 17, 2781). Its ester cry.staUizes in
large plates, melting at 58°, and boiling near 325°. The free acid is unstable.

CH.COjH

ffi-Propylene Tetracarboxylic Acid, C^HjO, = C^^^^^^H Its ethyl

\cH(COjH)j.
ester is formed from brommaleic ester and sodium malonic ester. The acid con-
tains two molecules of water of crystallization. These esjape at 100°. The anhy-
drous acid melts at 191°, with decomposition into COj and pseudo-aconitic acid
(p. 473) (Annalen, 229, 89).

^ Propylene-Tetracarboxylic Acid, CH(C02H)2.CH;C{C02H)j, dicar-
boxyl-glutaconic acid. Its ethyl ester results from the interaction of sodium

PENTAVALENT COMPOUNDS. 483

malonic ester and chloroform. When saponified with hydrochloric acid it yields
glutaconic acid. Sodium amalgam converts it into dicarboxyl-glutaric ester. It
splits off alcohol and then condenses to a pyrone derivative (Berichte, 22, 1419).

PENTAVALENT (PENTAHYDRIC) COMPOUNDS.

Arabite, C5H,A= CH,OH.(CH.OH)3.CH,OH, normal penta-
oxypentane, is formed from its aldehyde arabinose, C5H10O5, by
the action of sodium amalgam. It' crystallizes from hot alcohol in
shining needles, melting at 102". It has a sweet taste but does not
reduce Fehling's solution.

Arabinose, C5H10O5 == CH,(0H).(CH.0H)3.CH0, is its alde-
hyde. This was formerly thought to be a glucose, CeHijOe, although
it contains but five C-atoms, and belongs to the group of pentaglu-
coses or pentoses (p. 497). It is made from gum arable (also from
other gums which yield no, or at least but traces of, mucic acid,
when oxidized by nitric acid) on boiling with dilute sulphuric acid
{Berichte, ig, 3030).

It crystallizes in shining prisms that melt at 100°. It is dextro-rotatory, is
slightly soluble in cold water, has a sweet taste (less than that of cane sugar) and
reduces Fehling's solution, but is not fermented by yeast. Oxidation converts it
into arabonic acid, CjHjjOg (p. 484) and trioxyglutaric acid. Boiling mineral
acids convert it into furfurol, and not into laavulinic acid (as in the case of the car-
bohydrates).

Two molecules of phenylhydrazine and arabinose (like the glucoses) unite and
form a phenylosazone, C5Hg03(N2H.CgH5)2, melting at 158° (Berichte, 20,
345). Hydrocyanic acid, etc., converts it into /-mannonic and /-gluconic acids
(p. 490). The constitution of arabinose is thus established (Berichte, 20, 341,
1234). Sodium amalgam converts it into arabite.

Xylose, C^HjoOj, is alloisomeric with arabinose. It is obtained by boiling
wood-gum (beech- wood, jute, etc.) with dilute acids (Berichte, 22, 1046; 23, Ref.
15). It is perfectly similar to arabinose, and has also been included in the group
of pentaglucoses. It assumes a cherry-red coloration when digested with phloro-
glucin and hydrochloric acid. Its phenylosazone, like that of arabinose, melts at
160°. Nitric acid oxidizes it to trioxyglutaric and trioxybutyric acids.

Pentaoxyhexane, CgHjiOj = CH,(CH.0H)^.CH2.0H, is an homologous
pentahydric alcohol. It is rhamnite. (Berichte, 23, 3103). Its aldehyde is

Rhamnose, C5H12O5 = CHj^CH.OHj^CHO, or Isodulcite. It results
upon decomposing different glucosides (quercitrine, xanthoramnine, hesperidine)
with dilute sulphuric acid. It forms large vitreous crystals containing one mole-
cule of water. It melts at 93°- The crystals lose water at 100°, and form
C5H1J5O5. By the absorption of water they revert to CgHjiOg. Isodulcite
yiplds a-methylfurfurol when distilled with sulphuric acid (Berichte, 22, Ref. 751).

In its properties rhamnose resembles the glucoses, and (with arabinose and
xylose) is included under the Pentoses (p. 497). It reduces alkaline copper solu-
tions, but is not fermented by yeast. Being an aldehyde-alcohol it combines with
two molecules of phenylhydrazine to form an osa!ione,C^^ffi^{^^.C^^^,

484 ORGANIC CHEMISTRY.

melting at 180°. lis phenylhydrazone, Cf^^fi^{ii2Yi.CgH^), melts at 159°
(Berichte, 20, 2575). Hydrocyanic acid and hydrochloric acid convert it into
rhamnose carboxylic acid, CH,.(CH.0H)<.CH(0H).C02H (p. 491). Nitric
acid oxidizes it to trioxyglutaric acid (p. 485) {^Berichte, 22, 1702).

Quercite, CgHi^Os' *"'i Finite, C5H12O5, are two pentahydric derivatives
similar to arabite and the various sugars. The latest researches show that they
belong to the benzene series ; they will, therefore, be discussed under the poly-
hydric phenols.

MONOBASIC ACIDS.

Arabonic Acid, C5H1A =CH,(0H).(CH.0H)3.C0,H, tetra-
oxyvaleric acid, is obtained by the action of bromine water or nitric
acid upon arabinose {Berichte, 21, 3007). When liberated from
its salts by mineral acids, it splits off water and becomes the lactone
CsHgOs (Berichte, 20, 345). Further oxidation changes it to tri-
oxyglutaric acid. Its phenylhydrazide melts at 215°.

Saccharic Acid, CjHj^Osi tetraoxycaproic acid, readily changes, when free,
into Saccharin, its lactone : —

CH2(0H).CH(0H).CH(0H).C(0h/^q»jj

Saccharic Acid.

CH2(OH).CH.CH(OH).C(OH).CH3
O CO

Saccharin.

Calcium saccharate is obtained by boiling dextrose and laevulose (or from invert
sugar) with milk of lime. As soon as the acid is liberated from its salts it decom-
poses into water and saccharin {Berichte, 15, 2954). The latter dissolves with
difficulty in water (in 18 parts), forms large crystals, tastes bitter, melts at 160° and
sublimes without decomposition. It is reduced to o-methylvalerolactone (365) when
heated with hydriodic acid and phosphorus.

Aqueous saccharin possesses right-rotatory power ; the salts are Isevo-rotatory.

Nitric acid oxidizes it to saccharonic acid (p. 485). Oxidized with silver oxide
it yields glycollic, oxalic and also acetic acids. Boiling potash produces lactic
acid. Ljevulinic acid is not formed by the action pf hydrochloric acid {Berichte,
18, 1334). It yields a phenylhydrazide with phenylhydrazine. It melts at 165°.

Isomerides of saccharin : —

Isosaccharin, CjHidOj, results from the action of lime upon milk sugar
and maltose {Berichte, 18, 631). It is very similar to saccharin, and when
heated with HI and phosphorus it also yields o-methylvalerolactone. However,
it does not yield acetic acid with silver oxide, and when acted upon by nitric acid
it forms dioxypropenyl tricarboxylic acid (p. 486). See Berichte, 18, 2514, upon
the constitution of isosaccharic acid.

Metasaccharin, CjHj^Oj, is found in small quantities Jogether with the pre-
ceding (Berichte, 18, 642). It crystallizes in plates and melts at 142°. Hydri-
odic acid and phosphorus reduce it to normal caprolactone (p. 364). Nitric acid
oxidizes it to trioxyadipic acid, CgHi^O,.

TRIBASIC ACIDS. 485

DIBASIC ACIDS.

Aposorbic Acid, C^U^O^ = C3H3(OH)3(^^q2^ is produced on oxidizing

sorbine with nitric acid. It crystallizes in small leaflets which melt with decompo-
sition at 1 10°. It is easily soluble in water.

Trioxyglutaric Acid, CsHjO, = (CH.OH),/^^^^, appears to be different

from the preceding. It is found when arabinose, sorbinose and rhamnose are
oxidized with nitric acid {^Berichte, 22, 1698). The free acid crystallizes in small
plates, that melt at 118-120°.

Saccharon, CeHsOs, is the lactone of Saccharonic Acid,
CsHioO, : —

COjH.CH.CH(OH).C(OH).CH, COjH.CH.CH(OH).C(OH).CHj
OH COjH O CO

Saccharonic Acid. Saccharon.

Both are formed when saccharin is oxidized by nitric acid {An-
nalen, 218, 363).

The acid is quite soluble in water. It forms large crystals. In the dessicator
or when heated to 90° it breaks up into water and saccharon, which yields salts,
CjHjMeOg, with carbonates. On boiling, with HI and phosphorus, it is reduced
to o-methyl glutaric acid (p. 420). ,p^ „

Trioxyadipic Acid, CjHioO, = C^H5(OH)3('^Q2g_ results from the

oxidation of metasaccharin (see above) with dilute HNO3 {Berickie, 18, 1555).
It crystallizes in small laminse, and melts at 146° with decomposition. It is not
capable of forming a lactonic acid. Heated with HI and phosphorus it is reduced
to adipic acid, C ^li. ^{CO ^U.) ^.

TRIBASIC ACIDS.

Desoxalic Acid,C5HsO, = C5,H(OH)2(C02H)3,dioxyethenyl tricarboxylic
acid. Its tri-ethyl ester, C5H3(C2H5)30s, results from the action of sodium
amalgam upon diethyl oxalate. Large, shining prisms, which melt at 85°. Soluble
in 10 parts water and readily in ether. The free acid is obtained by saponifying
the ester with baryta water, decomposing the salt with sulphuric acid and slowly
evaporating the solution at 40°. The product is a crystalline, deliquescent mass.
When its aqueous solution is evaporated or when its ester is heated with water or
dilute acids to 100°, the acid yields carbon dioxide and racemic acid : CjHjOg =
C^HjOj + COj. Acid radicals can be substituted for the two hydroxyl groups of
the desoxalic ester. Heated with hydriodic acid desoxalic acid gives off carbon
dioxide, and is reduced to succinic acid. Its structure and transformation into
racemic acid are expressed by the following formulas: —

H0.C/^°«J^ HO.CH— COjH

I XCOa" = I + CO,.

HO.CH— COjH HO.CH— CO-H

Desoxalic Acid. Racemic Acid.

486 ORGANIC CHEMISTRY.

Oxycitric Acid, C^HjOj = CjH3(OH)2.(C02H)3, dioxytricarballylic acid,
accompanies aconitic, tricarballylic and citric acids in beet juice, and is produced
by boiling chlorcitric acid (from aconitic acid and ClOH) with alkalies or water
{Berichte, i6, 1078).

Dioxypropenyl Tricarboxylic Acid, CjHgOj = €3113(0^1)2(00211)3, re-
sults from tte oxidation of isosaccharin with nitric acid. It is a thick syrup. At
100° it loses carbon dioxide, and forms dioxyglutaric acid, C3Hj(OH)2.(C02H)2,
which is different from the dioxyglutaric acid obtained from glutaconic acid (^^-
richte, 18,2514). Hydriodic acid and phosphorus convert it into glutaric acid,

C3H,(C02H)2.

Propenyl Pentacarboxylic Acid, CgHgOj,, = €3113(002115), is a penta-
basic acid. Its ethyl ester is formed by the action of sodium malonic ester upon
chlorethenyl tricarboxylic ester (p. 471).

HEXAVALENT (HEXAHYDRIC) COMPOUNDS.

C3H3(OH)3 C,H3 } (0H)| c,H, } gH)^^^.

Mannitol, Dulcitol, Mannonic Acid, Saccharic Acid,

Sorbite. Gluconic Acid. Muctc Acid.

Since in all alcohols each carbon atom bears but one hydroxyl

group, we conclude that in the hexahydric alcohols, mannitol and

■ dulcitol, the six hydroxyl groups are attached to 6 different carbon

atoms. Mannitol, dulcitol and sorbite are reduced to secondary

hexyl iodide when heated with hydriodic acid (p. 95) : —

03H3(OH)3 + iiHI = CeH^I + 6H2O + Sl^-

The three are, therefore, derivatives of normal hexane, CeHu, and
normal hexoxy-hexane, QHsCOH^ = CH.,(OH)(CH.OH)4.CHj.
OH. They are examples of alloisomerism. To explain them, it
will be necessary to introduce stereochemical considerations.\

According to LeBel and vant' Hoff 's theory upon asymmetric carbon atoms,
the presence of one asymmetric 0-atom determines the existence of two modifi-
cations, differing chiefly in their opposite optical rotatory power. In the sexivalent
hexaoxyhexane there are four such asymmetrical carbon atoms; hence, a number
of modifications are possible. In fact, recent research has shown that we have not
only ordinary, right-rotatory or o'-mannitol, but also a Isevo-variety, and further that
these may combine to inactive, j'-mannitol. The latter is identical with so-called
a-acrite, derived from synthetic a-acrose. In this manner, it has been possible to
effect the synthesis of the compounds of the mannitol series (^Berichte, 23, 373).

'Y\it hexahydric alcohols approach the sugars very closely in their
properties. . They have a very sweet taste. They differ from them
inrthat they do not reduce an alkaline copper solution and are not
fermented by yeast. Their optical activity can only be observed
after the addition of borates. Moderate oxidation converts them

HEXAVALENT COMPOUNDS. 487

into glucoses, CeHuOs. They are obtained from the latter by the
action of sodium amalgam.

I. Mannitol or Mannite, QHuOg, exists in three modifications:
dextro-, laevo-, and inactive mannitol (see above). The ordinary,
or ^-mannitol, occurs rather frequently in plants and in the manna-
ash {^Fraxinus ornus), whose dried sap is manna. It is produced in
the mucous fermentation of the different varieties of sugar, and may
be artificially prepared by the action of sodium amalgam upon d-
mannose and fruit-sugar, and with more difficulty from grape sugar
{^Berichte, 17, 227): CeHi^Os -|- Hj^ CsHijOe. Mannitol is also
obtained by extracting manna with alcohol and allowing the solution
to crystallize.

Mannitol forms delicate needles or rhombic prisms ; it dissolves
in 6.5 parts of water at i6°, and readily in boiling alcohol. It pos-
sesses a very sweet taste and melts at i66°. Its solution is dextro-
rotatory in the presence of borax. When oxidized with care, it
yields fruit-sugar (called mannitose, Berichte, 20, 831), and man-
nose {Berichie, 21, 1805). Nitric acid oxidizes mannitol to sac-
charic acid and oxalic acid. Hydriodic acid converts it into hexyl
iodide (p. 486).

When mannitol is heated to 200° it loses water and forms the anhydrides, Man-
«!Vffl», CjHijOj, and Mannide,Q,^.^(P^^. The latter is also obtained by dis-
tilling mannitol in a vacuum. It melts at 87° and boils at 274° [Berichte, 17,
Ref. 108).

Mannitol resembles the sugars in combining with bases to yield compounds like
CgHnOg.CaO. When heated with organic acids mannitan esters are usually
produced : —

CsHi^Og -f 4Ci8H3,0, = C,H3(Ci3H350),05 -]- 5H,0.
Mannitol. Stearic Acid. Mannitan Stearate,

The hexacetate of mannitol, C5Hj(O.C2H30)5, is produced by heating man-
nitol with acetic anhydride; it is crystalline and melts near loo°-

Mannitol dichlorhydrin, C^Hg | L J*, is formed when mannitol is heated

with concentrated hydrochloric acid. It consists of laminae, melting at 174°- Hydro-

bromic acid yields the dibromhydrin, C^Hj | ^^ '^, melting at 178°.

Nitro-mannite, C8H8(O.NO.^)8, isobtained by dissolving mannitol in a mixture
of concentrated nitric and sulphuric acids. It crystallizes from alcohol and ether
in bright needles; it melts when carefully heated and deflagrates strongly. When
struck it explodes very violently. Alkalies and ammonium sulphide regenerate
mannitol. ■ ',

Laevo-mannitol, C^Hi^Oj, /-Mannite, is obtained by the reduction of /:man-
nose (from arabinose carboxylic acid, p. 488) in weak alkaline solutign with sodium
amalgam {Berichte, 20, 375). It is quite similar to ordinary mannite, but melts a
little lower (163-164°), and in the presence of borax is Isevorotatofy .'■*'•

Inactive Mannitol, C^"R^fi^, z-Mannite, is produced in a similar maniler,
from inactive mannose (from «-mannonic acid). It is identical with the syntheti-
cally prepared a-acrite (from a-acrose, p. 499) {Berichte^ 23, 383). It resembles

488 ORGANIC CHEMISTRY.

ordinary mannitol, melts 3° higher (at 168°), and in aqueous solution is inactive
even in the presence of borax. Nitric acid oxidizes it to irtactive mannose and
inactive mannonic acid. The latter can be resolved into d- and /-mannonic acids
{Berichte, 23, 391).

2. Dulcitol, Dulcite, CeHuOe, occurs in various plants and is
obtained from dulcitol ■ manna (originating from Madagascar
manna). It is made artificially by the action of sodium amalgam
upon milk sugar and galactose. It crystallizes in large monoclinic
prisms, having a sweet taste. It dissolves in water with more dif-
ficulty than mannite, and is almost insoluble in boiling alcohol. It
melts at 188°. The hexacetate, CeHeCO.CjHjOX, melts at 171°.
Hydriodic acid converts it into the same hexyl iodide that mannitol
yields. Nitric acid oxidizes dulcitol to mucic acid. There is also
an intermediate aldehyde compound that combines with two mole-
cules of phenylhydrazine and forms the osazone, C6Hio04(N2H-
€6115)2 {Berichte, 20, 1091).

(3) Sorbite, CgHj^^Oj + H^O, occurs in mountain-ash berries, forming small
crystals which dissolve readily in water. When heated they lose water and melt
near 110°. It is reduced to secondary hexyl iodide {Berichte, 22, 1048) when
heated with hydriodic acid and phosphorus. It corresponds, in all probability, to
grape sugar {Berichte, 23, 2623).

HEXAVALENT (HEXAHYDRIC) ALDEHYDES AND
KETONES.

When the hexahydric alcohols, CsHuOa, are carefully oxidized,
they lose two atoms of hydrogen, and are converted into their alde-
hydes and ketones. These products are identical wiih the glucoses
that occur naturally as such and are treated with these under the
carbohydrates. Polyhydric mono- and poly-carboxylic acids result
if the alcohols or glucoses are further oxidized : —

CeHi^O^.or C^Yi.,^Q^,ox C,H,,0„or

C,He(OH)5.CH,.OH. C5H,(0H),.CH0. C,H,(OH)5.CO,H.

Hexahydric Alcohols. Glucoses. Mouocarboxylic Acid.

Mannitol. Fruit Sugar, Mannose. Mannonic Acid, Gluconic Acid,

MONOBASIC ACIDS.

The penta-oxy-monocarboxylic acids are produced by the further
oxidation of the alcohols and glucoses corresponding to them. They
may also be obtained synthetically from the pentoses (arabinose,
rhapnose, p. 483) by the aid of HCN, etc. (p. 494) : —

C.HioO, yields C.H^COHjs.CO^H.

Arabinose, Arabinose Carboxylic Acid.

HEXAVALENT ALDEHYDES AND KETONES. 489

Being j'-oxy-derivatives, nearly all of these acids are very unstable
when in a free condition. They lose water readily and pass into
lactones {^1. 352): QHuO, = CsHioOs + H^O. When acted upon
in acid solution by sodium amalgam, these lactones (not the acids)
reabsorb two atoms of hydrogen, and are converted into the cor-
responding glucoses (E. Fischer, Berichte, 22, 2204; 23, 370, 799,
930) (p. 494) : CeHioOe + H, = QH^Oe-

Thus, the three mannonic acids yield three mannoses, the three
gluconic acids three glucoses, and galactonic acid galactose.

These acids (like other carboxylic acids), when acted upon with one mole-
cule of phenylhydrazine, lose the hydroxyl of the carboxyl group, and form (^&x-
&c\.er\s,\\c pheny/kydrazides, CgHjjOg.NgHj.CgHj (p. 495). The latter generally
result on healing the acids (l part) with phenylhydrazine (l part), water (10 parts),
and 50 per cent, acetic acid (j part). They usually separate from the solution in
a crystalline form [Berichte, 22, 2728). They are resolved into their components
when boiled with alkalies. They are distinguished from the hydrazones of the
aldehydes and ketones by the reddish-violet coloration produced upon mixing them
with concentrated sulphuric acid and a drop of ferric chloride.

These acids are reduced to normal caprolactone, if they are heated
with hydriodic acid and phosphorus (p. 364). They must, there-
fore, be considered as pentaoxycaproic acids, having the same struc-
tural formula, C5H6(OH5).C02H, and are physical or geometrical iso-
merides (p. 486). Gluconic and mannonic acids also occur in
dextro- and Isevo-rotatory modifications. These unite and produce
inactive forms (^Berichte, 23, 371, 2623).

1. Mannitic Acid, CgHj^O,, is obtained by the action of platinum black
upon aqueous mannitol. It is a very soluble gummy mass which reduces Fehling's
solution {Berichte, 23, 3223).

2. Gluconic Acid, CoHijO,, exists in a dextro-, a Isevo- and
an inactive form. ^/-Gluconic Acid is formed by the oxidation
of dextrose, cane sugar, dextrine, starch and maltose with chlorine
or bromine water, and is most readily obtained from glucose {Be-
richte, 17, 1298). Gluconic acid, separated from its lead salt by
hydrogen sulphide, forms a syrup which is almost insoluble in alco-
hol. When evaporated, or upon standing, it changes in part to its
crystalline lactone, CeHuOe, melting at 130-135°. Its barium salt
crystallizes with three molecules of water, the calcium salt with one.
The acid is dextro-rotatory, but does not reduce Fehling's solution.

Its phenylhydrazide, CeHnOeCN^H^.CeHj), crystallizes in bril-
liant leaflets and prisms. When rapidly heated it melts about 200°.
{Berichte, 23, 802, 2625).

When ^-gluconic acid is heated to 140° with quinoline it is converted into
aT-mannonic acid. And, the latter, when similarly treated, becomes (/-glu-

41

49° ORGANIC CHEMISTRY.

conic acid. A state of equilibrium occurs in this case similar to that observed in
the transposition of racemic acid and mesotartaric acid when heated with water
(p. 479). If sodium amalgam be allowed to act upon the lactone of gluconic
acid, when in a cold, acid solution, it is changed to grape sugar {^Berichte, 23 ,

/-Gluconic Acid is obtained by heating /-mannonic acid. This is similar to
the formation of (/-gluconic acid from fZ-mannonic acid (see above). A more con-
venient course consists in exposing arabinose to the action of CNH, etc. This
acid is more soluble than /-mannonic acid, and is, therefore, found in the mother
liquor from the latter. It is separated by means of its phenylhydrazide, CjH, ,0j.
N2H2.C5H5. This melts at 200° {Berichte, 23, 2613). Heated to 140° to-
gether with quinoline, it is partially converted into /-mannonic acid.

?-Gluconic Acid (and its lactone) is formed upon evaporating the aqueous solu-
tion of a mixture of d- and /-gluconic acids. Its calcium salt dissolves with diffi-
cully. The acid is inactive. Its phenylhydrazide is also inactive. It melts at
190° (Berichte, 23, 2618).

The three gluconic acids yield the three corresponding saccharic acids, when
they are oxidized with nitric acid (p. 492). The three glucoses result upon their
reduction (p. 503).

3. Mannonic Acid, CsHijO,, occurs as dextro-, laevo- and in-
active mannonic acid.

Ordinary or a? mannonic acid is produced when ordinary (/-mannose is oxidized
with bromine water. It is obtained pure by boiling its phenylhydrazide with
baryta water {Berichte, 22, 3220). When the solution is evaporated it solidifies
to a crystalline mass. This is the /arfow^, CjHjjOj, which crystallizes from alcohol
in long shining needles, melting at 149-153°. The aqueous solution of the lac-
tone is neutral and dextro-rotatory \a\„ = + 53.8°. Its phenylhydrazide,
C5HijOj(N2Hj.CsH5) crystallizes from hot water in brilliant prisms, melting
at 214-216°. When the acid is heated to 140° together with quinoline, it changes
to gluconic acid (see abovej.

Laevo-mannonic Acid, CgHj^O^, is identical with arabinose-carboxylic
acid, obtained from arabinose by the action of hydrocyanic acid, etc. {Berichte,
19, 3033). It is further produced, together with laT-mannonic acid, by the decom-
position of «-mannonic acid. When its solution is concentrated it passes into the
/a^/o»i?, CjHjjOj. The latter crystallizes from alcohol in needles that dissolve
with difficulty. They become soft at 140-150°. Its solution is Isevo-rotatory
[a] „ = 54.8°. The phenylhydrazide of /-mannonic acid is very similar to that
of (/-mannonic acid. It also melts at 214-216°. /-Mannose and /-mannitol result
from the reduction of /-mannonic lactone (p. 487).

Inactive Mannonic Acid, CjHijOj. 2-mannonic acid, is obtained by the
union of equal parts of d- and /-mannose. Its lactone, CgHjoOj, separates in
colorless radiating crystals, when the solution is evaporated. When the latter is
concentrated the crystals assume a prism form. The lactone melts somewhat
higher than its components, softens at 149° and fuses at 155°. The phenylhydra-
zide of the acid crystallizes from hot water in forms similar to those of sodium
chloride. When rapidly heated it melts at 230°. The acid can be resolved into
its components if it be fermented by penicillium glaucum, or by the crystallization
of the strychnine salt. Sodium amalgam converts it into j-mannose and !-man-
nite, which is identical with a-acrite — prepared synthetically from aacrose. If
j-mannite be oxidized with nitric acid it yields z-mannose, which bromine water
can further change to i-mannonic acid. Thus, the synthesis of all the members
of the mannite series has been realized {Berichte, 23, 391).

DIBASIC ACIDS. 49 1

When the mannonic acids are oxidized with nitric acid they yield the correspond-
ing mannosaccharic acids (p. 494).

4. Lactonic Acid, CgHujO:,, galactonic acid, is produced from millc sugar,
galactose and gum arabic by the action of bromine water (Berichte, 18, 1552).
It crystallizes, on standing over sulphuric acid, in small needles. Prolonged heat-
ing to 100° converts it into the corresponding lactone, C^HioO^*. Its phenylhy-
drazide crystallizes in brilliant laminae, melting at 200-205°. Sodium amalgam
causes the lactone to revert to galactose (Berichte, 23, 935.) It yields mucic acid
on oxidation with nitric acid. /OH

Rhamnose-carboxylic Acid, C,Hi^O, = CH3(CH.0H)^.CH/^q jj ,

from rhamnose, is homologous with the preceding acids. When its solution is
evaporated it leaves the lactone, C,Hi20g, a crystalline mass, melting at 162-
\(i%° {^Berichte, 21,2173). Its phenylhydrazide, C,Hi30g.N2Jl2.CjH5, forms
six-sided leaflets, melting about 210° (Berichte 22, 2733).

When the acid is heated with hydriodic acid and phosphorus it is reduced to
normal heptylic acid. Sodium amalgam converts the lactone into methylhexose,
CjHi^Oe = C,H„(CH3)0e (Berichte 23, 936).

Glycuronic Acid, CjHj„Oj = CKO. (CH.0H)^.C02H, a tetraoxyaldehydic
acid, is obtained by decomposing euxanthic acid (see this) on boiling with dilute
sulphuric acid. Various glucoside-like compounds of glycuronic acid with camphor,
bomeol, chloral, phenol and different other bodies (Berichte, 19, 2919; Ref. 762)
occur in urine after the introduction of these compounds into the system. Boiling
acids decompose them into their components. Glycuronic acid is a syrup, which
rapidly passes into the lactone CjHjO, on warming. The latter consists of large
plates, of sweet taste, melting at 169° C. Bromine water oxidizes it to saccharic
acid. It also appears that when saccharic acid is reduced glycuronic acid results
(Berichte, 23, 937).

DIBASIC ACIDS.

C(OH)2.C02H
1. Tetra-oxysuccinic Acid, C.H.O. = I , Dioxytartaric Acid.

C(OH)2.C02H
This was formerly regarded as carboxytartronic acid, C(0H).(C02H)g. It is
obtained when protocatechuic acid, pyrocatechin and guaiacol, in ethereal solu-
tion, are acted upon with NjOj, or from nitro-tartaric acid through the action of
an alcoholic solution of nitrous acid (Annalen, 221, 246). The addition of sodium
carbonate to the aqueous solution separates the sodium salt, C^H^Na^Oj +
zHjO, as a sparingly soluble crystalline powder. When heated with water it
decomposes into CO^ and sodium tartronate, CgH^NajOj. The free acid, obtained
from the sodium salt by means of hydrochloric acid and ether, is crystalline. It
melts with decomposition at 98° (Berichte, 22, 2015). On reducing the acid with
zinc and hydrochloric acid, it passes into inactive tartaric acid and racemic acid.
This deportment is explained by the fact that tetraoxysuccinic acid represents a

CO.COjH
diketonic acid, I , which, like glyoxylic acid and mesoxalic acid, con-

CO.COjH
tains two molecules of water that may be readily split oft.

Being a diketonic acid dioxytartaric acid combines with I and 2 molecules of
phenylhydrazine, forming,

C02H.C(OH)2 CO^H.CN^H.C.H,

I and I

COjH.GN^H.CeHs CO^H.&N^H.C.H^

Phenylizine dioxytartaric acid. Diphenylizine dioxytartaric acid.

492 ORGANIC CHEMISTRY.

The first melts with decomposition at 218°. The second is an orange yellow
powder, yielding yellow salts with bases. Concentrated (fuming) sulphuric acid
converts it into a disulpho-acid, which is also formed by the union of dioxytartaric
acid' with phenylhydrazine-sulplipnic acid. The disodium salt of this acid,
COjjH.C-.NjH.CjH^.SOaNa

I ■ , is an orange yellow powder. As Tartrazine, it is

COjH.GN^H.CjH^.SOaNa
applied as a yellow dye for wool {Berichte, 20, 834).

2. Acids, CeHioOs = C,H,(0H),(C0,H)2..

There are four known isomeric acids of this formula : saccharic,
mucic, isosaccharic and manno-saccharic acids. All are obtained
by the oxidation of various carbohydrates with nitric acid, and are
readily prepared from the corresponding monocarboxylic acids,
C6He(OH)5. CO2H (p. 488), upon oxidation with chlorine or bromine
water. Gluconic acid yields saccharic acid, galactonic mucic acid,
arabinose carboxylic acid, manno-saccharic acid, while the mono-
carboxylic acid, corresponding to isosaccharic acid, is not known.
When reduced by III and phosphorus all four acids are converted
into normal adipic acid, QH8(C02H)2 ; hence all of them must be
considered as normal tetraoxyadipic acids. They are physical or
stereochemical isomerides.

I. Saccharic Acid, CeHuOs, Acidum saccharicum, like glu-
conic and mannonic acids, exists in three modifications : dextro-,
Isevo- and inactive saccharic acid. Ordinary, or ^/-saccharic acid,
results in the oxidation of cane sugar, ^Tglucose (grape sugar),
(/-gluconic acid, and many other carbohydrates with nitric acid.

Cane sugar (l part) is heated with common nitric acid (3 parts) until a stormy
reaction sets in, then cooled and heated anew to 50°, until brown vapors cease
coming off. The liquid is then diluted with ^ volume of water, saturated with
potassium carbonate, and an excess of acetic acid added. In the course of a few
days the primary potassium sal: will separate in hard crystals, which may be puri-
fied by recrystallization from hot water. The free acid is obtained by decomposing
the cadmium salt with hydrogen sulphide, or the silver salt with hydrochloric acid
(Berichle, 21, Ref. 472).

Ordinary, ^/-saccharic acid forms a deliquescent, gummy mass,
readily soluble in alcohol. If the pure, syrupy acid be allowed to
stand for some time, it changes to its crystalline lactonic acid,
CgHsO,, that melts at 130-132° {Berichte, 21, Ref. 472). When
prepared from cane sugar, its solution is Isevo-rotatory and reduces
ammoniacal silver solutions. It turns brown at 100° and decom-
poses. When oxidized with nitric acid, dextro-tartaric acid and
oxalic acid are formed. Hydriodic acid reduces it to adipic acid.

It forms acid and neutral salts. The primary potassium salt, CjHgKOj, and
the ammonium salt, CeH5(NH4)Oj, crystallize well and dissolve with difficulty in
cold water. The neutral alkali salts are deliquescent ; the salts of the heavy metals

MUCIC ACID. 493

are insoluble. The diethyl ester, C^Yi.^{0Yi>)4(X)^.C^\\^)^, is crystalline and is
readily soluble in water. With ammonia it forms the ainide, C4H^(OH)j(CO.NHj)2,
a white powder. When acetyl chloride acts on the ester we obtain the tetra-ace-
tate, CjH4(O.C,H30)4.(C02.CjH5)j, which forms prisms, melting at 6i° ; insoluble
in water. Acetyl chloride, acting upon free saccharic acid, converts it into the
lactone of diaceiyl-sauharic acid, Q.^^^(:).Z^f))f)^, melting at l88°.

Two molecules of phenylhydrazine and rf-saccharic acid form a diphenylhydra-
zide, C5HgOg(N2H2.C|;H.)2, that melts at 210° with decomposition (p. 489 and
Berichte, 21, Ref. 186).

/-Saccharic acid is obtained upon oxidizing /gluconic acid with nitric acid. It
is quite similar to (/saccharic acid, but is lasvorotatory. It also forms a dihydra-
zide, melting at 214°.

/-Saccharic acid is formed when /-gluconic acid is oxidized, or by mixing (/-sac-
charic with /-saccharic acid. It is inactive and forms a dihydrazide, melting at
210°.

The monopotassiiim salts, CgHgOjK (Berichte, 23, 2621), are characteristic
derivatives of the three saccharic acids.

2. Mucic Acid, CeHioOg, Acidum mucicum, is obtained in the
oxidation of dulcitol, milk-sugar, galactose, galactonic acid and
nearly all the gum varieties.

Preparation. — Heat 100 grams of lactic acid with 1200 c.c. of nitric acid (sp.
gr. 1. 15), until the volume is reduced to 200 c.c. Cool, and wash the mucic acid
that is formed with water (Berichte, 227, 224).

It is a white crystalline powder, soluble in 60 parts of boiling
water. It is almost insoluble in cold water and alcohol. It melts
at 210° with decomposition. When boiled for some time with water
it passes into an isomeric paramucic acid. Boiling nitric acid de-
composes it into racemic acid andoxalicacid. Hydriodic acid reduces
it to adipic acid.

The neutral potassium salt and ammonium salt, C^H^(^Yi^ fig, crystaWize
well and dissolve with difficulty in cold water; the primary salts dissolve readily.
The silver salt, CjHgAgjOg, is an insoluble precipitate. When heated the neutral
ammonium salt decomposes into NHj, water and pyrrol, C4H5N.

The diethyl ester, €4114(011)4(002.02115)2, is obtained by heating mucic acid
and alcohol with sulphuric acid. It is crystalline, is soluble in hot water and melts
at 158°. Acetyl chloride converts it into the tetra- acetate, which melts at 177°-
The free acid also forms a tetra-acetyl compound (Berichte, 21, Ref. 186).

The ready conversion of mucic acid into furfurane derivatives
is rather retnarkable. Digestion with fuming hydrochloric or
hydrobromic acid changes it to furfurane dicarboxylic acid
(dehydromucic acid) : —

/COjH
CH(OH).CH(OH).C02H CH = C^
I =1 > O + 3H2O.

CH(0H).CH(0H).C02H CH = C

494 ORGANIC CHEMISTRY.

When mucic acid is heated alone it splits off carbon dioxide and
becomes furfane monocarboxylic acid (pyromucic acid) : —

C,H,(OH),(CO,H), ^ CjHaO.CO.H + 3HP + CO,.

Heated with barium sulphide it passes in like manner into a-thio-
phene carboxylic acid {Berichte, 18, 456).

3. Isosaccharic Acid, CgHjjOg (see above), results from HCl-glucosamine
(p. 505) upon oxidizing it with nitric acid {Berichte, 19, 1258). It is very soluble
in water and alcohol, forms rhombic crystals and melts at 185°. Its solution is
dextrorotatory; (a)„ = 46.1°. Its diethyl ester, Q,^fi^[<Zfi^^,'saA\s at 73°.
Acetyl chloride converts the ester into the tetra-acetyl compound, Q^^{p.Q^^')^.
(CO^.CjHjjj, melting at 47°. Hydriodic acid reduces isosaccharic acid to normal
adipic acid (see above).

Like mucic acid it yields furfane derivatives. It breaks up into water, carbon
dioxide and pyromucic acid when distilled. Dehydromucic acid is formed on
heating isosaccharic, acid in a current of hydrogen chloride. Pyromucic acid and
a-thiophene carboxylic acid are produced when the iso-acid is heated with barium
sulphide. When its diethyl ester is heated with alcoholic ammonia anhydro-
(zVawiiisfe, CjHjO.(OH)2.(CO.NH2)2, is produced; this by distillation yields pyro-
mucamide, C^^.CO.'^Yi^i^Berichte, ig, 1277).

4. Metasaccharic Acid, CjHjjOg, /-mannosaccharic acid, is produced by
oxidizing arabinose carboxylic acid with nitric acid {Berichtej2X>, 2710; 23, 2131).
On evaporating the solution, its double lactone, CjHjOj + 2H2O, crystallizes. It
has a neutral reaction, and on standing over sulphuric acid loses two molecules of
water. When air-dried it melts at 68°, and when anhydrous, at 1 80°. Hydri^
odic acid reduces it to adipic acid. Sodium amalgam converts it into mannite,
CgHj^Oj (^Berichte, 22, 2204).

The diphenylhydrazide of metasaccharic acid, C^H^(OH)4.(CO.N2Hj.C5H5)j, is
produced on heating the double lactone with phenylhydrazide and sodium acetate.
It melts at 213°. Concentrated sulphuric acid and ferric chloride color it red
(p. 489). Acetic anhydride converts the double lactone into the diacetyl deriva-
tive, C8H405(C2HgO)2, melting at 155° [^Berichte, 21, 1422; 22, 524).

Butane Hexacarboxylic Acid, Cj^Hj^Ou ^ 0^11^(00211)5, is a hexabasic
acid. Its hexa-ethyl ester is formed by the action of iodine upon the sodium com-
pound of ethenyl tricarboxylic ester (p. 471). It forms hexagonal plates, which
melt at 56° {^Berichte, 17, 2786).

HEPTAVALENT (HEPTAHYDRIC) COMPOUNDS.

Perselte, C,H]gO, = C,Hg(0H),, is an heptahydric alcohol. It is found in
the leaves and geeds of Laurus persea. It is artificially prepared by reducing its
aldehyde mannoheptose, C,Hj^0, (p. 507), with sodium amalgam {Berichte, 23,
935). It crystallizes in needles, melting at 184°. At 250° it parts with water,
and forms a compound resembling mannitan. It does not reduce Fehling's solu-
tion, and is not fermented by yeast. Nitric acid reoxidizes it to mannoheptose.

The heptahydric aldehydes, CiH^O,, resemble the sugars in
their behavior. They will be discussed with them under the desig-
nation oiheptoses (p. 507).

GLUCOSE-CARBOXYLIC ACID. 495

The heptahydric monocarboxylic acids, CjHiiOg, are obtained
synthetically from the hexaglucoses or hexoses, CeHuOe, by the
action of hydrocyanic acid, and the subsequent transformation
of the oxycyanides first formed (Kiliani, Berichte, 19, 767 ; 21, 915.
E. Fischer, Berichte, 22, 370) : —

CHa(OH)(CH.OH)4.CHO yield CH2{OH)(CH.OH)4.Ch/°q ^

Glucoses, Galactoses, Mannoses. Glucose-, Galactose-, and Mannose-

Carboxylic Acid.

CHj(OH)(CH.OH)3.CO.CHj.OH yields CHj{OH)(CH.OH)3.C(OH)/^^^2°^
Fructose. Fructose-Carboxylic Acid.

Glucose-, galactose-, and mannose-carboxylic acids have the
same constitutional formulas. They also yield normal heptylic
acid, C5H13.CO2H, when reduced with hydriodic acid and phos-
phorus. Therefore, they are either to be considered as physical
or stereochemical isomerides.

Like other carboxylic acids, all of these acids combine with phenylhydrazine to
form phenylhydrazides, C,Hj jOf.NjH^.CjHj, which are distinguished from the
phenylhydrazones by the violet coloration they give when acted upon with sul-
phuric acid and ferric chloride {^Berichte, 22, 2728).

Sodium amalgam reduces these acids (their lactones) to the corres-
ponding aldehydes or aldoses, C7H14O7 (this is similar to the reduc-
tion of the pentaoxy-monocarboxylic acids to the hexoses, CeHi-jOs,
p. 489) :—

CH2(OH).(CH.OH)5.C02H yields CH2(OH)(CH.OH)5.CHO.

These are the higher synthetic varieties of sugar — the heptoses.
From the latter, it is possible, by similar reactions, to obtain the
heptocarboxylic acids and the octoses, corresponding to them (E.
Fischer, Berichte, 22, 2204; 23, 930).

Glucose-carboxylic Acid, CjH^Og, hexaoxyheptylic acid, is obtained from
dextrose (grape sugar) by means of CNH, etc. The lactone, CjHi20,, crystallizes
from the concentrated solution. This is a neutral substance, that dissolves readily
in water. It softens about 145°. Hydriodic acid and phosphorus reduce it to
heptolactone, CjHj jO^, and normal heptylic acid. Sodium amalgam reduces the
lactone to dextroheptose (glucoheptose) (p. 507) {Berichte, 23, 936). The phenyl-
hydrazide of dextrose-carboxylic acid melts at 171°. Pentaoxypimeltc acid (p. 496)
is formed when dextrose-carboxylic acid is oxidized with nitric acid.

(/-Mannose-carboxylic Acid, CjHi^Og, from ordinary (/-mannose (p. 503),
separates from concentrated solutions as a lactone, CjHijO,, in warty crystals. It
is very soluble in water, has a neutral reaction, and melts at 148-150°. Hydriodic
acid and phosphorus reduce the acid to heptolactone and heptylic acid (see above
and Berichte, 22, 370). l\s phenylhydrazide (see above) melts about 220° with
decomposition. Sodium amalgam reduces the lactone to mannoheptose, C,H]^0,,
and then to the heptahydric alcohol perseite, C,H,bO, {Berichte, 23, 936, 2226).

496 ORGANIC CHEMISTRY.

Galactose-carboxylic Acid, C,H]^Og, from galactose, crystallizes in minute
hydrous needles. It has an acid reaction. After the acid has been dried over
sulphuric acid it melts at 145°, and passes into its lactone ; this is also produced
on heating the solution. It consists of needles, melting at 150°. Sodium amal-
gam changes it into galaheptose, CjHjjOj.

Fructose-carboxylic Acid, CjHj^Oj, is obtained from leevulose by the action
of hydrocyanic and hydrochloric acids (BericAte, ig, 222). When oxalic acid
acts upon its calcium salt, it liberates a mixture of the acid and its lactone, C,HjjO,.
Reduction with hydriodic acid forms heptolactone and heptylic acid, C,Hi402.
The latter is identical with melhyl-normal butyl acetic acid (p. 230). Hence it is
evident that lavulose is a ketone-akohol

Pentaoxy-dicarboxylic Acids, C5H5(OH)5/^q2H.

Pentaoxy-pimelic Acid, CjHjjOj, is produced in the oxidation 01 dextrose-
carboxylic acid with nitric acid. The lactone is crystalline, and melts at 143°
(^Berichte, ig, 191 7).

Carboxy-galactonic Acid, CjHi^Oa, is formed in the oxidation of galactose-
carboxylic acid with nitric acid. It dissolves with difficulty in water, crystallizes
in plates, and melts at 171° with decomposition [Berichie, 22, 523). Aldehyde-

galactonic Acid, C,Hi20g = C ^W. ^[OH.) ^'C ^^ „, is a transition product in

the formation of the preceding acid. It is an analogue of glycuronic acid (p. 491)
{Berichte, 22, 1385).

Butane-heptacarboxylic Acid, C4H3(C02H)j, is a heptacarboxylic acid,
formed by the action of chlormalonic ester, CHCl (C02R)2, upon sodium propenyl-
pentacarboxylic ester (p. 486). It boils at 280-285° under a pressure of 130 mm.

Higher polycarboxylic esters have been prepared in an analogous manner i^Be-
richte, 21, 2 113) : —

Hexane decacarboxylic Ester, C|.H4^(C02R)io, is produced by the action
of chlor-propenyl pentacarboxylic ester (p. 486) upon sodium-propenyl-pentacar-
boxylic ester. It is a yellow oil.

Octan-tesserakaideca-carboxylic Acid, CjH4(C02R)i4, is the highest
polycarboxylic acid that has been prepared. It is obtained from sodium butane-
heptacarboxylic ester and chlorbutane-hepfacarboxylic ester. It is a thick oil
(^Berichte, 21, 21 13).

OCTO- AND NONO-HYDRIC COMPOUNDS.

rf-Manno octite, CjHjjOj, is an octohydric alcohol. It is produced when
(/-mannoctose is reduced with sodium amalgam. It dissolves with difficulty in water,
crystallizes in small plates, melts at 258°, and sublimes without decomposition.
Its aldehyde is described on p. 507 as manno-octose.

(/-Mannooctonic Acid, CgHijOg.has been obtained as a syrup by the action
ofCNH, etc, upon a'-mannoheptose, CjlIj^O,. Its hydrazide, CjHjsOj.NjHj.
C5H5, is crystalline, and melts at 243°. The /af/o«^, CgHj^Og, has a neutral
reaction, a sweet taste, and melts about 1 68°. . By reduction it forms (/-mannoctose
(^Berichte, 23, 2234).

i/' Mannononite, CjIIjuOg, is a nono-hydric alcohol. It may be prepared by
reducing its aldehyde, mannononose, CjHjgOj (p. 507) with sodium amalgam.

o^-Manno-nononic Acid, CjHjjOiq, has been obtained from manno-octose.

GLUCOSES. 497

CgH, sO,, by means of CNH, etc. Its hydrazide, C9H1 jOj.NjH^.CgH^, dis-
solves wiih difficulty, and melts about 254°. Its lactone, CgHj ^Og, forms minute
needles, melting at 176°. When reduced it forms a'manno-nonose, CjHjjOg
(P- S°7} {Berichte, 23, 2236).

CARBOHYDRATES.

This term is applied to a large class of compounds, widely dis-
tributed in nature. They contain six, or a multiple of six carbon
atoms. The ratio of their hydrogen and oxygen atoms is the same
as that of these elements in water. The carbohydrates may be ar-
ranged into three groups : the glucoses, CsHuOe, grape sugar and
fruit sugar; the sugars, CijITzjOn, or disaccharides, as cane sugar,-
and the polysaccharides (CeHioOs)^ as starch and dextrine. The
glucoses were discovered to be the aldehyde- or ketone-derivatives
of the hexahydric alcohols (chiefly through the investigations of
Kiliani (1885) upon the hydrogen cyanide addition-products), into
which they might be converted by the absorption of two hydrogen
atoms. Consequently, they could be produced by the oxidation of
the alcohols. The di- and polysaccharides proved to be ethereal
anhydrides of the glucoses (similar to polyglycols, p. 304) ; inasmuch
as all of them could be converted into the glucoses by hydrolytic
decomposition. The more recent and widely extended researches
of E. Fischer have amplified these views quite considerably, and in
many cases modified them very materially (^Berichte, 23, 21 14).
The glucose character of a compound is very much affected by its
constitution, as aldehyde alcohol — CH(OH).CHO, or ketone
alcohol — CO.CHj.OH, and we thus have glucoses containing not
only six, but even a less or greater number of carbon and oxygen
atoms. According to the number of the oxygen atoms, they are
known zs, pentoses, hexoses, heptoses, octoses, etc. It is also obvious
that only those compounds contain twice as many hydrogen atoms
as oxygen atoms in which the number of oxygen and carbon atoms
is equal, /. e., those in which the valence corresponds to the number
of carbon atoms — as the pentoses, CsHujOs, and hexoses, CeHjaOe,
whereas rhamnose (methyl pentose) has the formula CeHiaOa, and
methyl hexose, the formula QHuOe-

I. GLUCOSES (MONOSES).

The glycoses, or glucoses, are mostly crystalline substances, very
soluble in water, but dissolving with difficulty in alcohol. They
posS"Ssa sweet taste. Their reducing power distinguishes them from
other sweet-tasting, polyhydric alcohols, e ^..glycerol, erythrol and
mannitol. This is in accord with their aldehyde or ketone charac-
ter. The aldehyde alcohols, containing the atomicgroup — CH(OH).
42

498 ORGANIC CHEMISTRY.

CHO, are also known as aldoses, while the ketone alcohols — CO.
CHj.OH, have been called ketoses. The reducing properties of the
latter correspond to those of acetyl carbinol, and the analogous
a-ketols (p. 321).

(i) Glycerose, CgHgOj, Triose, derived from glycerol, may be considered the
loweat glucose. It consists of a mixture of glycerol aldehyde and dioxy- acetone,
CH2(OH) CO.CH2{OH) (p. 454).

(2} Erythrose, C^HjO^, Tetrose, from eryihrol, probably represents a mixture
of an aldose and a ketose.

(3) Pentoses; Arabinose and Xylose, CjHjjOs, and Rhamnose,
CuHjjOj, methyl arabinose, belong to this class. They are aldoses or aldehyde
derivatives of pentahydric alcohols, with which they are more fully discussed
(p. 483). They manifest the general character of hexoses, in that they reduce
Fehling's solution, yield osazones with phenylhydrazine, but cannot be fermented.
They readily pass into furfurol when distilled with sulphuric and hydrochloric
acids (Berichic, 23, 1751).

(4) Hexoses. These are the aldehyde or ketone derivatives of
the hexahydric alcohols. Mannose, glucose and galactose are alde-
hyde derivatives. Fructose and probably sorbinose are ketoses.
These compounds correspond to the formulas : —

CHj(OH).(CH.OH)j,.CHO and CHj(OH).(CH.OH)3.CO.CH2(OH).
Glucose, Mannose, Galactose. li'ructose. Sorbinose.

This is evident from the conversion of the glucoses, by means
of CNH, etc., into the corresponding hexa-oxy-carboxylic acids,
and also by the reduction to heptylic acids. The first three yield
normal heptylic acids, while fructose is converted into methyl-
butyl acetic acid (pp. 495, 496). Bromine water, even in the cold,
oxidizes the aldoses to their corresponding monocarboxylic acids
(p. 489), whereas the ketoses (fructose and sorbinose) are not
attacked {Berichte, 23, 2116).

Mannose, glucose, and galactose have the same structural formula,
and are therefore (like the hexahydric alcohols, p. 486) alloisomeric
^r stereo-isomeric compounds. Mannose and fructose are derived
from mannitol ; galactose is the aldose of dulcitol, while glucose
(grape sugar) probably corresponds to sorbite (p. 4^8). Further, ,
mannose, glucose, arid fructose, in accordance with the hypothesis
of asymmetric carbon atoms (like mannitol, p. 487) exist in three
optically different modifications — the dextro-, the laavo-and inactive
forms.

In some reactions the glucoses behave differently from the aldehydes. Thus,
they do not oxidize on exposure to the air, and do not react with fuchsine-sulphu-
rous acid (p. 189). The penta-acetyl- and penta-benzoyl derivatives of dextrose
and galactose "do not manifest an aldehyde character {Berichte, 21, 2842; 22,
Ref. 66g). It has therefore been assumed that the hexoses possess a constitution
similar to ethylene oxide or the \&xX.ox\es, [Berichte, ^^, 22\\). However, it is

HEXOSES. 499

hardly probable that this assumption is correct [Berichte, 21, 2841 ; 22, 2212;
23, 21 17).

The hexoses occur frequently in plants, especially in ripe fruits.
They are formed by the hydrolytic decomposition of all di- and
poly-saccharides when they are boiled with dilute acids, or by
ferments (p. 507). Mannose and fructose have been made artifi-
cially by oxidizing mannite. A more common method pursued in
the formation of the glucoses is to reduce the monocarboxylic
acids (their lactones) with sodium amalgam in acid solution {^Be-
richte, 23, 930). Different hexoses have been directly synthesized
by the condensation of formic aldehyde, CHjO, acrolein, CsHjO,
and glyceric aldehyde, CsHjOs : —

6CH,0 = CsH,,Oe 2Z^fi^ = CjH^.O,.

Formic Formose. Glyceric Acrose.

Aldehyde. Aldehyde.

E. Fischer (1890) effected the complete synthesis of grape sugar
and fruit sugar by these methods.

Methylenitan was the first compound, resembling the sugars, that was pre-
pared. Butlerow (l86l) obtained it by condensing trioxymethylene (p. 192) with
lime water. O. Loew (1885) ohKwa^i. formose [/our.pr. C/iemie, 33, 321) in an
analogous manner from oxymethylene, and somewhat later the fermentable
vielhose, by the use of magnesia [Berichie, 22, 470, 478). E. Fischer considers
these three compounds mixtures of different glucoses, among which a-acrose
occurs {Berichte, 22, 360). The latter (together with /3-acrose) is obtained by
the action of barium hydroxide upon acrolein bromide, C3H50Br2. This is
probably because the glyceric aldehyde in it condenses {Berichte, 23, 389, 2131).
By reduction with sodium amalgam a-acrose (identical with inactive fructose)
passes into a-acrite, identical with inactive mannitol (p. 487). When the latter is
oxidized it yields z-mannonic acid, which can be resolved into d- and / mannonic
acid (p. 490). By reduction these acids are converted into d- and /-mannose.
(/-Mannose is changed through its osazone into ^/-fructose, i. e., fruit sugar (p. 505)
(E. Fischer, Berichte, 23, 373). af-Mannonic acid is converted into a'-gUiconic acid
when heated, and by reduction with sodium amalgam the latter becomes <f-glucose,
i.e., grape sugar (Berichte, 23, 799).

The hexoses show the ordinary aldehyde reactions : —
(i) By reduction they become hexahydric alcohols. Mannose
and fructose yield mannitol, galactose yields dulcitol, and sorbite
seems to result from the reduction of glucose (grape sugar).

(2) The oxidation of the hexoses does not occur directly upon
exposure to the air. Oxidizing agents are necessary. Hence tliey
show feeble reducing power. They precipitate the noble metals
from solutions of their salts, and even reduce ammoniacal silver
solutions in the cold. A very marked characteristic js their
ability to precipitate cuprous oxide from warm alkaline cupric
solutions (this is accelerated by tartaric acid). One molecule of
hexose precipitates about five atoms of copper, as CujO. This is

500 ORGANIC CHEMISTRY.

the basis of the volumetric method for the estimation of the glu-
coses by means of Fehling's solution. Maltose and milk sugar, of
the di- and polysaccharides, only act directly upon the application
of heat. The others must be first \con verted into glucoses (p. 508).

To prepare Fehling's solution, dissolve 34.65 grams of crystallized copper
sulphate in water, then add 200 grams Rochelle salt and 600 c.crh of NaOH
(sp. gr. 1. 1200), and dilute the solution to i litre. 0.05 gram hexose is required
to completely reduce 10 c.c. of this liquid. The end reaction is rather difficult to
recognize, hence it is frequently recommended to estimate the separated cuprous
oxide gravimetrically {Berickte, 13, 826; Jour. pr. Chem., 21, 524). Consult
Berichte, 23, 1035 for Soldaini's suggestion of using a copper carbonate solution
for the estimation of the hexoses.

The hexoses are converted into their corresponding mono-
carboxylic acids (p. 488) by moderated oxidation with chlorine
and bromine water, or silver oxide. More energetic oxidation
changes them to saccharic and mucic acids. Milk sugar yields
both acids at the same time. When boiled with dilute hydrochloric
or sulphuric acid the hexoses, and apparently all the carbohydrates,
sustain a gradual oxidation, the product being Isevulinic acid,
CsHgOa (p. 343) {Berichte, 21, 230).

When the glucoses are heated with dilute alkalies they turn brown, and pass
into humus-like compounds. Saccharinic acids are produced when they are
boiled with lime. Tiie hexoses form tartaric acid chiefly when they reduce an
alkaline copper solution.

In many reactions, for example, when heated alone or with sulphuric acid, we
find that nearly all the carbohydrates yield traces of furfarol. This may be
detected by the red coloration it yields with aniline {Berichte, 20, S41). The
reaction of Molisch, for the detection of carbohydrates by means of anaphlhol
and sulphuric acid (production of deep violet colors), is due to this compound
(Berickte, ig, Ref. 746; 20, Ref. 517; 21, 2744).

(3) Being aldehydes or ketones the glucoses unite with hydro-
cyanic acid to form cyanhydrins. These yield the monocarboxylic
acids. They combine with HjN.OH to form oximes. Only those
of galactose and mannose have been isolated {Berichte, 20, 2673).

(4) The phenylhydrazine derivatives are especially interesting
(pp. 191, 326). If one molecule of the phenylhydrazine (acetate)
is allowed to act the first product will be a hydrazone, CeHi^Os.
(N.NH.CsHj). This class of compounds dissolves readily in water
(with the exception of those derived from the mannoses and the
higher glucoses, Berichte, 23, 2118). They generally crystallize
from hot alcohol in colorless needles. Cold concentrated hydro-
chloric acid resolves them into their components.

Diphenylhydrazine, H2N.N(C6H5)2, often produces dipheny-
hydrazones, C6Hi205:N2(C6H5J2 {Berichte, 23, 2619), that dissolve
with difficulty.

HEXOSES. 50T

In the presence of an excess of phenylhydrazine the hexoses,
like all glucoses, combine with two molecules of it upon applica-
tion of heat and form the osazones (E. Fischer) : —

CeHi.O^ + 2H,N.NH.C,H5 = C.Hi^O.lN.NH.C.HJ, + 2H,0 + H,.

Glucosazonc.

The reaction is carried out by adding two parts of phenylliydrazine, two parts of
50^ acetic acid, and about twenty parts of water to one part of glucose. This
mixture is digested for about one hour upon the water bath/ The osazone then
separates in a crystalline form (^Berichte, 17, 579; 20, 822; 23, 21 17). In this
reaction a hydrazone is first produced, and one of its alcohol groups, adjacent to
either an aldehyde or ketone group, is oxidized to CO (inasmuch as two hydrogen
atoms in the presence of phenylhydrazine produce aniline and ammonia), which
then acts further upon a second molfecule of phenylhydrazine. The same ^/ucosa-
zone, CH2(OH).(CH.OH)3.C(N,H.CeHg).CH(N2H.C8H5) (see BeHchte, 23,
21 18), is thus obtained from mannose, glucose and fructose.

The osazones are yellow colored compounds (see larlrazine, p. 492). They are
usually insoluble in water, dissolve with difficulty in alcohol, and crystallize quite
readily. When glucosazone is reduced with zinc dust and acetic acid it becomes
isoglucosamine (p. 505). Nitrous acid converts the latter into fructose {Berichte,
23, 2110). The reformation of the hexoses from their osazones is readily effected
by digestion with concentrated hydrochloric acid ; they are then resolved into
phenylhydrazine and the osones [BeHchte, 22, 88; 23, 2120) : —

C,Hj„0,(N,H.C,H,), + 2H,0 =

Glucosazone.

CH2(OH).(CH.OH)3.CO.COII + 2N2H3.C6H5.

Glucosone.

The osones dissolve readily in water, and have not been obtained free. They
combine, like ketone-aldehydes, with two molecules of phenylhydrazine and form
an osazone (p. 326). They are converted into glucoses by reduction (when
digested with zinc dust and acetic acid). In this way fruit-sugar is prepared from
glucosazone [Berichte, 23, 2121).

The osones yield quinoxalines with the orthodiamines. The glucoses also com-
bine directly with the ortho-phenylenediamines [BeHchte, 20, 281).

The alcoholic character of the hexoses is made manifest in the
following reactions : —

I. The hydrogen of the hydroxyls can be" readily replaced by
acid radicals. The mixture of nitric and sulphuric acids (p. 454)
, converts them into esters of nitric acid-^the nitro compounds
(p. 514). The acetyl esters are best obtained by heating them
with acetic anhydride and sodium acetate (or ZnCl^). Five acetyl
groups are thus introduced {Berichte; 22, 2207). The benzoyl
esters are prepared with even less difficulty, it being only necessary
to shake the hexoses with benzoyl chloride and caustic soda (p. 299).
Pentabenzoyl derivatives are then formed {Berichte, 22, Ref.
668).

An elementary analysis will not yield a positive conclusion as to the number of
acidyls that have entered compounds like those just mentioned. This is ascer-

502 ORGANIC CHEMISTRY.

tained by first saponifying them with titrated alkali solutions, or better, with mag-
nesia {^Berichte, 12, 1531). Or, the acetic esters are decomposed by boiling them
with dilute sulphuric acid. The acetic acid that distils over is then titrated {An-
nalen, 220, 217 ; Berichte, 23, 1442). The presence of hydroxyl in the glucoses
may also lie proved by means of phenylisocyanate, with which they form carbani-
lic esters {Berichte, 18, 2606).

Alkyl-sulphuric acids result upon treating the glucoses with
chlorosulphonic acid, CIHSO3. This is similar to the behavior of
alcohols when exposed to like treatment {Berichte, 17, 2457).
Anilides of the glucoses are formed when the latter are digested
with the anilines. This is due to the replacement of a hydroxyl
group {Berichte, 21, Ref. 399).

The esters of sugars with organic acids do occur abundantly in
plants and are termed glucosides. Thus, the tannins are glucosides
of aromatic acids. All glucosides yield their components, when
heated with acids or alkalies, or through the action of ferments.

The alcoholic hydrogen of the glucoses can also be replaced by
bases, like CaO, BaO, and PbO, forming saccharates, which corres-
pond to the alcoholates, and which are again decomposed by car-
bon dioxide.

The hexoses can be made to undergo fermentation quite readily
when exposed to schizomycetes. They sustain various decompo-
sitions. The alcoholic fermentation is especially important. It is
induced by yeast cells.

Alcoholic Fermentation. — This is indiiced by yeast, which is composed of micro-
scopic (o.oi mm.) cells of Saccharomyces cerevisits and vini, which multiply during
fermentation by budding. Alcoholic fermentation occurs at temperatures varying
from 3—35° and is most rapid from 20-30°. Oxygen is requisite at the commence-
ment, but it afterwards proceeds without air access. The hexoses mainly decom-
pose, during fermentation, into alcohol and carbon dioxide : C^yf)^ = aC^HgO
-|- 2CO2. Glycerol (as much as 2.5 per cent.), succinic acid (0.6 per cent.), and
fusel oils are formed simultaneously. Tke hexoses ferment directly, grape sugar
somewhat more rapidly than fruit sugar. The di saccharates, CjjHjjOn, are first
decomposed by the soluble ferment of the yeast into hexoses ; hence their fermen-
tation proceeds very slowly and demands more yeast.

Other budding fungi, like Mueor mucedo, cause alcoholic fermentation. The
fermentation phenomena -occasioned by schizomycetes are exceedingly interesting.
It is evident that the production of fusel oils in ordinary yeast fermentation (butyl
and amyl alcohol) is due to these.

Alcoholic fermentation can occur unaccompanied by organisms in unimpaired,
ripe fruits (grapes, cherries), providing the latter are exposed to an atmosphere of
carbon dioxide.

In the lactic acid fermentation, the hexoses, milk sugar and gums decompose
directly into lactic acid ■>—

CjHijOj = 2C3H5O3.

The active agents are Uittle, wand-like organisms (bacteria and micrococci).
Decaying albuminous matter (decaying cheese) is requisite for their development,
and it only proceeds in liquids which are not too acid (p. 357). The temperature

GLUCOSE. 503

most favorable varies from 30-50°. By prolonged fermentation tlie lactates suffer
butyric fermentation ; this is owing to the appearance of other bacilli fp. 2261 :
2C3HSO3 = C,HA + 2CO, + 2H,. ^'^ ^

In mucous fermentation chain-like cells (of o.ooi mm. diameter) appear. These
convert grape sugar, with evolution of carbon dioxide, into a mucous, gummy sub-
stance; mannitol and lactic acid are formed at the same time.

Almost all the naturally occurring carbohydrates are optically
active, as their solutions deviate the plane of polarization. Their
specific rotatory power (p. 62) is not only governed by tem-
perature and the concentration of their solutions, but is also very
frequently influenced by the presence of inactive substances
{Berichte, 21, 2586 and 2599). Further, some substances show the
phenomena of bi-rotation and semi-rotation. Brief heating of their
solutions will usually bring about a recurrence of constant rotation.
The determination of the rotatory power of the carbohydrates by
means of the saccharimeter serves to ascertain their purity and is
frequently applied in estimating their percentage content — optical
sugar test.

1. Mannose, CeHijOg, is the aldehyde of mannitol. Like the
latter, it exists in three forms (p. 487) : dextro-, Isevo- and inactive
mannose.

(/-Mannose was firf,t prepared by oxidizing ordinary o'-mannitol (logether with
(/fructose) with platinum black or nitric acid [Berichte, 22, 365). It is also ob-
tained from salep mucus [Annalen, z^g, 251 ; Berichte, 21, 2150), and most easily
from seminine (reserve-cellulose), occurrins; in different plant seeds, when this is
boiled with dilute sulphuric acid (hence called seminose) {Berichte, 22, 609, 3218).
(/-Mannouic acid yields it upon reduction. It is an amorphous mass, very soluble
in water, and dextro-rotatory. It reduces Fehlino;'s solution, and is fermented by
yeast {Berichte, 22, 3224). Its hydrazone dissolves with difficulty in water, and
forms brilliant leaflets, that melt at 195°. Its osa%one,<Zfi.^fP^{^^.C^^^^,
is identical with (/-glucosazone. Nascent hydrogen converts it into (/-mannitol.
Bromine oxidizes it to (/-mannonic acid. Hydrocyanic acid causes it to pass into
(/-mannoheptonic acid (p. 495).

/-Mannose results when /-mannonic acid is reduced (p. 490, Berichte, 23,
373). It is very similar to the preceding compound, but is Isevo-rotatnry, and is
fermented wilh more difficulty. Its hydrazone also dissolves with difficulty, and
melts at 195°. It unites with two molecules of phenylhydrazine to form /gluco-
sazone (see below). It becomes /-mannitol by reduction.

/-Mannose is formed by the reduction of inactive mannonic acid. It is quite
similar to the two preceding compounds, but is inactive. Its hydrazone dissolves
with difficulty, melts at 195°, and is inactive. Its osazone is /-gluccsazone. Yeast
decomposes it, the (/-mannose is fermented, and /mannose remains (Berichte, 23,
382)-

2. Glucose, CeHijOs, is probably the aldehyde of sorbite, and
occurs as dextro- Isevo- and inactive glucose (p. 498).

(/-Glucose, or Grape Sugar, formerly called dextrose, occurs
(always with fruit sugar) in many sweet fruits and in honey ; also

504 ORGANIC CHEMISTRY.

in the urine in Diabetes vieUiius. It is formed by the hydrolytic
decomposition of poly-saccharides (cane sugar, starch, cellulose)
and glucosides. It is prepared on a large scale by boiling starch
with dilute sulphuric acid (see ^mc^/if, 13, 1761). The synthesis
of grape sugar has been made ppssible by tlie production of glucose
in the reduction of d-gluconic acid (p. 499).

Commercial grape sugar is an amorphous, compact mass, containing only about
60 per cent, glucose, along witli a dexlrine-iike substance (gallesine, €,21^240,5),
which is not fermentable (Berichie, 17, 2456). Pure grape sugar, wiih one mole-
cule of water, cnn lie prepared from this, l>y crvstal ization from alcohol.

The best method for preparing pure crystallized grape sugar consists in adding
to 80 per cent, alcohol, mixed with ^'^ volume fuming hydrochloric acid, finely
pulverized cane sugar, as long as the latter dissolves on shaliing {Juuin. frakt.
Chem., 20, 244).

Grape sugar crystallizes from water at the ordinary temperature,
or dilute alcohol, with one molecule of water, in nodular masses,
melting at 86°; at 110° it loses its water of crystallization. At
30-35° it crystallizes from its concentrated aqueous solution, and
from its solution in ethyl or methyl alcohol, in anhydrous, hard
crusts, melting at 146° {Berichie, 15, 1105).

Grape sugar is not quite so sweet to the taste as cane sugar, and
serves to doctor wines.

Aqueous grape sugar is dextro-rotatory [re]„ ^= 52.6°, and exhibits bi-rotatory
power, i. e , the freshly prepared solution deviates the polarized r.iy almost twice
as strongly as it does after standing some time. At ordinary temperatures the
deviation doe? not become constant untd the expiration of twenty-four hours,
whereas when boiled it does so in the course of a few minutes. Furthermore, the
specific rotation of dextrose is appreciably augmented by concentration [Berichte,
17, 2234). This is dependent upon the decomposition of more complex crystal-
molecules into normal molecules. This has been proved by determining the mole-
cular weight by the method of RaouU {Beiichle,2i, Ref 505).

Wiih barvta and lime grape sugar forms saccharates, like C|.H,20g.CaO, and
CjHjjOj.BaO. These are precipitated by alcohol. Wiih NaCl it forms large
crvslals, 2CsH,20g.NaCl -f- HjO, which sometimes separate in the evaporation
of (I'ahetic urine.

When grape sugar and acetyl chloride are heated, so-called acetocMorhydrose,

CjHjO S (o r H 01 ' ''^^''''^- '^'^'^ ''^^ \iexxi used in the synthesis of the disac-
charates.

Grape sugar exhibits all the properties of the aldoses (p. 498).
\Xs, phenylhydrazone is very soluble and melts at 145°.*

d-Glucosazone, its osazone, consists of yellow needles, melting
at 204-205° to a red liquid. Its aqueous solution is laevo-rotatory.

* .SUraup (^Berichte, 22, Ref. 669) maintains that grape sugar forms two hydra-
zones with phenylhydrazine, the one melting at 143°, and the other at 116°.

FRUIT SUGAR. 505

It may also be prepared from //-mahnose and fl'-fructose, as well as from
glucosamine and isoglucosamine. Invert sugar is best adapted for
the preparation of (/-glucosazone (see below, Berichte, ig, 1921).
Concentrated hydrochloric acid converts rf-glucosazone into phenyl-
hydrazine and glucosone, CsHjoOe (p. 501); which regenerates
^-ghicosazone with two molecules of phenylhydrazine. It is a non-
fermentable liquid, and if it be reduced with zinc and acetic anhy-
dride, is converted into fruit sugar (= (/-fructose) {Berichte, 22, 88).

The following are derivatives of grape sugar : — •

Isoglucosamine, CgHigNO^ =;= CH2(OH)(CH.OH)3.CO.CH2.NH2, is
formed hy reducing glucosazoiie with zinc rlust and acetic acid. It reduces alka-
line copper s)lutions, combines with phenylhydrazine to re firm t/glucosazone and
is converted by nitrous acid into fruit sugar {Beric/ite, 23, 2120).

Glucosamine, CjHj^NOj, is produced on warming chitine (found in lobster
sheila) with concentrated HCl (Berickte,\T, 243). Free jilucnsamine separates from
alcohol in needles. Nitric acid oxidizes it to isotaccharic acid. It forms glucosa-
zone wiih phenylhydrazine.

/-Gluco^e.CjHjjOg, is formed when the lactone of /-gluconic acid (p. 490) is
reduced with .=odium amalgam. It is perfectly similar to grape sugar. It melts at
143°, but is Issvo-rotatory, [«]„ = — 514°. Its glucosazone is, however, dextro-
rotatory, lis difi/imylkytirazone, C^Hj |,05:N.N(^C5 115)2, dissolves ^'''^ difficulty,
and melts at 163° [Berichle, 23, 2618).

2-Glucose, CjHjjO,., results from the union of d- and /glucose, and by the
reduction of /-gluconic lactone. Phenylhydrazine converts it into i-glucosazone,
Q.^\1.^^0^{^^\l.Q,^\i^^. This may also be obtained from /-mannose. It crys-
tallizes in yellow needles, melting at 217-218°- The same /-glucosazone is pro-
duced from synthetic a-acrose (fructose), (/-mannose, (/glucose and (/-fructose
(fruit-sugar) {^Berichte, 23, 383, 2620). Inactive fructose is formed when /-gluco-
sazone is decomposed with hydrochloric acid, and by the reduction of the /-gluco-
sone, first formed, with zinc dust and acetic acid. Diphenylhydrazine and /-glu-
cose yield a diphenylhydrazone, crystallizing in leaflets, melting at 133°- /-Glucose
is fermented by yeast. /-Glucose remains behind.

3. Fruit Sugar, CsHijOs, is the ketone derivative (the ketose)
of marinitol. It occurs as dextro-, Isevo- and inactive fruit sugar

(p. 498)-

(/-Fructose, or Fruit Sugar, formerly called Icsvuiose, is found
in almost all sweet fruits, together with an equal amount of grape
sugar. It is likely that cane sugar first forms in the plants and that
a ferment at once breaks it up into grape sugar and fruit sugar. It
is formed, together with grape sugar, in the so-called inversion, or
decomposition of cane sugar, by boiling with acids or by the action
of ferments. The mixture of the two is called /«»ifr/w|ar. The de-
composition of inosite yields fruit sugar. It is artificially prepared
(together with (/-mannose) by oxidizing (/-mannitol, as well as
from (/-glucosazone and isoglucosamine. In this way the complete
synthesis of fruit sugar has been effected (p. 499).

Preparation. — Mix ID parts invert sugar with 6 parts calcium hydroxide and 50
parts of water. On pressing the moist mass, the liquid lime compound of dextrose

5o6 ORGANIC CHEMISTRY.

is removed and the residual solid is the lime compound of Isevulose. This is decom-
posed by oxalic acid, the lime oxalate filtered off, and the solution evaporated
{Berickle, 14, 2418).

A much simpler method is to heat inuline, with water, to 100° for twenty-four
hours, when it is completely changed to Isevulose [Anna/en, 205, 162; Berichte,
23, 2107).

Fruit sugar forms a thick syrup which at 100° dries to a gummy,
deliquescent mass. When the syrup is repeatedly extracted with
cold absolute alcohol, the laevulose gradually crystallizes out in fine,
silky needles, which fuse at 95° and lose water at 100°. It is more
readily soluble in water and alcohol than grape sugar, and rotates
the plane to the left more powerfully than the latter. Its specific
rotatory power in 20 per can):, solution is ■[«]„ = — 71.4° at 20°
(^Berichte, 19, 393). Consequently invert sugar (grape sugar and
fruit sugar) is laevo-rotatory. Fruit sugar is more slowly fermented
by yeast than grape sugar; therefore in the fermentation of invert
sugar the solution finally contains only fruit sugar.

In all reactions fruit sugar closely resembles grape sugar, and
reduces an alkaline copper solution in the same proportion as the
latter. It is converted into rf-mannitol by sodium amalgam. It
yields the same ^f-glucosazone with phenylhydrazine. However, in
oxidations it sustains, owing to its ketone character, more complete
decompositions, resulting in the production of gluconic and tartaric
acids. Hydrochloric and hydrocyanic acids convert it into fruc-
tose-carboxylic acid, which may be reduced to methylbutyl acetic
acid (p. 496).

/-Fructose, CjHjjOj, is produced by fermenting inactive fructose (a-acrose)
with yeast ; the a?- fructose being destroyed. It has not been isolated, but yet forms
/-glucosazone (p. 505) with phenylhydrazine (^Berichle, 23, 389).

/-Fructose, inactive tevulose, is probably identical with synthetic a-acrose.
Sodium amalgam converts it into a-acrite, identical with zmannitol (p. 4S7).
Yeast breaks it up, leaving /-fructose. Its osazone is identical with j'glucosazone,
from which j-fruclose can again be regenerated. ci-Acrite can also yield z'-manno-
nic acid, and the latter fruit sugar and grape sugar.

4. Galactose, CjHijOj, Lactose, is the aldose of dulcitol (p. 488). It is
formed on boiling milk sugar with dilute acids, and is obtained from such gums
(called galactans) [Berickle, 20, 1003), as yield much mucic acid when oxidized.
To prepare it boil milk sugar with dilute sulphuric acid [Annalen, 227, 224). It
crystallizes in nodules of grouped needles or leaflets, which melt at 166°; it dis-
solves with much more difficulty in water than rf-glucose. Its solution is dextro-
rotatory. It readily reduces alkaline copper solutions and is fermentable with
yeast [Berichte, 21, 1573). Nitric acid oxidizes it to mucic acid, bromine to
galactonic acid (p. 491) and sodium amalgam converts it into dulcitol. Hydro-
cyanic and hydrochloric acids convert it into galactose-carboxylic acid. Phenyl-
hydrazine converts galactose into a hydrazone, CjH^^OsiNjH.CgHj, melting at
158°, anA galaciosazone, CjHjoO^.fNjH.CgHs)^, melting at 193°.

5. Sorbinose, Sorbine, CjHijOg, a ketone alcohol (ketose), is found in
mountain-ash berries, and consists of large crystals, which possess a very sweet
taste. It reduces alkaline copper solutions, but is incapable of fermentation under

DISACCHARIDES. 507

the influence of yeast. Oxidized with nitric acid it yields trioxyglutaric acid
[Berichte, 21, 3276). Its osazone, sorbinosazone, melts at 164°.

6. Methyl Hexose, C^Yi^^O^ = C5Hji(CH,)0j, rhamno-hexose, is pro-
duced in the reduction of rhamnose-carboxylic acid (p. 491). It crystallizes quite
readily from alcohol and melts at 181° Its osazone melts near 200° (Berichte,
23. 936). Hydrocyanic acid and hydrochloric acid convert it into methylheptonic
acid. This yields methylheptone by reduction.

(5) Heptoses, CyH^Oj.

These compounds are synthetically prepared by reducing the corresponding
heptonic acids, C^Hj^Og (their lactones), with sodium amalgam. In their
properties they are very similar to the hexoses. They are not fermented by yeast
(^Berichte, 23, 935).

fl'-Manno-heptose,C,Hj jOj.is obtained frpm mannoheptonic acid {Berichte,
23, 2228). Perseite yields it when oxidized (p. 494). It crystallizes in needles
melting at 135°. Its hydrazone, C,H]40|j{N2H.C„Hj), dissolves with difficulty
and melts about 198°. Its osazone, Q^Yi.-^^0^{^^.C^Yi.^^, melts near 200°.
Sodium amalgam converts it into perseite (p. 494). Manno-octonic acid,
CjHjgOg, is obtained upon treating It with hydrocyanic and hydrochloric acids
{Berichte, 23, 2233).

(/•Gluco-heptose, CjHj40,, from gluco-heptonic acid, crystallizes in beautiful
plates, meliing at 190°. Its hydrazone is very soluble. Its osazone melts at 197°.
Hydrocyanic acid and hydrochloric acid convert it into gluco-octonic acid.

Gala-heptose, CyHj^O,, from galaheptonic acid, forms a hydrazone that
dissolves with difficulty. Its osazone melts about 220°-

Methyl Heptose, CgHi^Oj =: C,ii^(CHg)0^, riamno-he/iiose, is derived
from methyl heptonic acid. Its hydrazone dissolves with difficulty.

(6) Octoses, CjHijOj and Nonoses, CjHjjOg. The octoses are derived
from the heptose-carboxylic acids.

</-Manno-octose, CjHuOg, from manno-octonic acid (p, 496), is syrup-like,
but yields a beautiful hydrazone and osazone. Sodium amalgam converts it into
i/manno-octite, CgHijOg (Berichte, 23, 2234). Prussic and hydrochloric acids
convert it into izf-manno-nononic acid, CgHigOj^ (p. 496). By reduction the
latter yields

(/-Manno-nonose, CjHuOg. This is very similar to grape sugar. It fer-
ments under the influence of yeast. The heptoses and octoses do not ferment.
The hydrazone melts at 223°, the osazone about 217° {Berichte, 23, 2237).

2. DISACCHARIDES.

Only the disaccharides of the hexoses, CsHijOe, are known.
They consist of two molecules of the glucoses or monoses (p. 497),
and therefore are called btoses. Their formula would therefore
be C12H22O11. By the absorption of water— by hydrolysis— they
are resolved into two molecules of the hexoses: —

CijHj.Oii + H,0 = 2C,Hj,0,.

Thus cane sugar decomposes into grape-sugar (^-glucose) and
fruit-sugar (rt?-fructose), milk sugar into ^-glucose and galactose,
maltose into two molecules of (/-glucose, etc., etc., etc.

508 ORGANIC CHEMISTRY.

When the di- and poly-saccharides are heated with water and a litUe acid they
undergi hydrolysis. Its rapidity, according to Ostwald, bears a close relation to
the affinity of the aciJs {jour, pr. Ckeni. (2), 31, 307). The action of various
unorganized ferments., sucli as diastase and synaptase or emulsin (contained in
sweet and Liner almonds), upon the saccharides produces a similar decomposition.
Invertin (the ferment of yeast), ptyalin (the ferment of saliva), trypsin, pepsin,
and other animal secretions exert a like action. Thus, yeast resolves cane sugar
into grape sugar and fruit sugar, and starch into dextrine and maltose.

Formerly the decomposition of cane sugar was termed inversion, because the
optical rotation was reversed (owing to the stronger Isevo-deviation of the plane
by the fruit sugar). The product (a mixture of dextrose and ItevuloSe) is invert
sugar (■^. <iol').

Prolonged heating with acids causes reversion ; the glucoses (especially fructose)
undergo a retrogressive condensation to dextrine like substances [Beric/Ue, 23,
2094).

The constitution of the disaccharides indicates that they are
ether-like anhydrides of the hexoses. The union is effected through
the alcohol or aldehyde groups. Milk sugar and maltose also
contain the aldose group, CH(OH).CHO, because they reduce
Fehling's solution upon boiling, form osazones with phenylhydra-
zine, and when oxidized with bromine water yield monobasic acids,
CizHjjOij, lacto- and malto-bionic acid (p. 510) {Berichfe, 21,
2633; 22, 361).

Cane sugar does not show reducing power and does not yield an
osazone. The reducing groups (of grape sugar and fruit sugar)
appear to be combined in this compound. It is consequently not
capable of direct fermentation with yeast. Inversion must first
take place. Maltose is fernnented quite readily, while milk sugar
ferments with difificulty. After inversion cane sugar forms the same
glucosazone as grape sugar and fruit sugar.

Cane Sugar, C12H22O11 = Ci2H„03(OH)8, Saccharose, occurs
in the juice of many plants, chiefly in sugar cane, in some varieties
of maple and in beet-roots (10-20 per cent.) from which it is pre-
pared on a commercial scale. While the hexoses occur mainly in
fruits, cane sugar is usually contained in the stalks of plants..

Its commercial manufacture from cane or beet sugar is, from a chemical point
of view, very simple. The sap obtained by pressing or diffusion is boiled with
milk of lime, to saturate the acids, and precipitate the albuminoid substances.
The juice is next saturated vvith carbon dioxide, filtered through animal charcoal,
concentrated in a Roberts' Machine, and further evaporated in vacuum pans to
a thick syrup, out of which the solid sugar separates on cooling. The raw sugar
obtained in this manner is further purified with a pure sugar solution, in the
centrifugal machine, etc. — refined sugar.

The syrupy mother liquor from the sugar is called molasses; it contains
upwards of 50 per cent, of cane sugar which is prevented from crystallizing by
the presence of salts and other substances. It is either converted into alcohol or
the cane-sugar is extracted from it by the fermenting process. The sparingly
soluble saccharates of lime and strontium are obtained from the molasses (see

DISACCHARIDES. 5O9

below) and these are freed from impurities by washing with water or dilute alcohol.
The purified saccharates are afterwards decomposed by carbon dioxide, and the
juice which is then obtained, after the above plan, is further worked up.

When its solutions are evaporated slowly cane sugar separates in
large monoclinic prisms and dissolves in yi part water of medium
temperature; it dissolves with difficulty in alcohol. Its sp. gr.
equals 1.606. Its aqueous solution is Isevo-rotatory ; the influence
of concentration upon the specific rotation is slight ; it, however,
diminishes (opposite of grape sugar) with increased concentration.
Its real rotatory power, A^, at 20° is -f- 64.1 (p. 62). Cane sugar
melts at 160° and on cooling solidifies to an amorphous glassy
mass ; in time this again becomes crystalline and non-transparent.
At 190-200° it changes to a brown non-crystallizable mass, called
Caramel, which finds application in coloring liquors.

Cane sugar decomposes into dextrose and laevulose (invert sugar)
when boiled with dilute acids. Mixed with concentrated sulphuric
acid it is converted into a black, humus-like body. Sacccharic
acid, inactive tartaric acid and oxalic acid are formed when it is
boiled with nitric acid.

Cane sugar yields saccharates (p. 502) with the bases. An aqueous sugar solu-
tion readily dissolves lime. If finely divided burnt lime (CaO) (i molecule to i
molecule sugar) be dissolved in a dilute sugar solution (6-12 per cent.) alcohol
will precipitate the monobasic saccharate, Cj2H2 20i].CaO + 2H2O, which,
when deprived of its water at 100°, is a white amorphous mass, that is quite
soluble in cold water. Two molecules of CaO afford C12H22O, ,. 2CaO, which
separates, in the cold, in beautiful crystals. If CaO be added to its solution at
temperatures below 35°, all the sugar will be precipitated as tribasic saccharate,
Ci2H220ii.3CaO; this is not readily soluble in water. Upon the above deport-
ment is based C. Steffen's substitution process, by which sugar is separated from
molasses [Beric/ite, 16, 2764). Strontium and barium give perfectly similar sac-
charates [Berichte, 16, 984). On boiling the sugar solution with lead oxide we
get Ci2Hi8Pb20ii.

Cane sugar heated to 160° with an excess of acetic anhydride gives octacetyi
ester, C^^Yi^^O ^(O.C^'R^O\ \ this is a white mass, insoluble in water and acetic
acid. The action of concentrated nitric acid and sulphuric acid yields the tetra-
nitrate, Ci2Hig(N02)40ii, a white mass; it explodes violently.

Milk Sugar, CijHjjOu -f HjO, Lactose, has thus far been
found in the animal kingdom only, and occurs in the milk of
mammals, in the amniotic liquor of cows, and in certain patholog-
ical secretions.

Milk sugar is prepared from whey. This is evaporated to the point of crystal-
lization and the sugar which separates purified by repeated crystallization.

Milk sugar crystallizes in white, hard, rhombic prisms, contain-
ing one molecule of water. It is soluble in 6 parts cold or 2j^
parts hot water, has a faint sweet taste, and is insoluble in alcohol.

510 ORGANIC CHEMISTRY.

Its aqueous solution is dextro-rotatory and exhibits bi-rotaiion
(p. 504). When the constant rotatory point is obtained by heating,
the specific rotatory power will vary considerably with the concen-
tration. Milk sugar loses its water of crystallization at 140°, chars,
melts at 205°, and suffers further decomposition. It resembles the
hexoses in reducing ammonical silver solutions; this it effects even
in the cold, but in case of alkaline copper solutions boiling is
necessary to reach the desired end. Milk sugar yields galactose
and (/-glucose when it is heated with dilute acids ; it ferments with
difficulty with yeast, but undergoes the lactic fermentation with
great readiness. Nitric acid oxidizes it to saccharic acid, mucic
acid and additional oxidation products.

Bromine water converts it into lactobionic acid, Q,^.^^fi^^, which is changed
to gluconic acid and galactose upon digesting it with acids [Serichte, zz, 361).

An octacetyl" ester is obtained by treating the acid with acetic anhydride. A
so-called nitro-lactose, Ci2Hi,(N02).,Oii, crystallizes from alcohol in leaflets.
This melts at 139° and explodes at IS5°.

It unites with phenylhydrazine and iotxoi phenyl-lactosazone, Q-^^^f^O^.i^^.
CgHj)^, that melts at 200° [Berichte, 20, 829).

Maltose, CisHj^On -|- H^O, is a variety of sugar formed,
together with dextrine, by the action of malt diastase (p. 508) upon
starch (in the mash of whiskey and beer). It is capable of direct
fermentation. It was formerly supposed to be grape sugar. It is
also an intermediate product in the action of dilute sulphuric acid
upon starch, and of ferments (diastase, salivaj pancreas) upon gly-
cogen (p. 513).

In the normal sugaring of pasty starch by diastase, at a temperature of 50-63°,
nearly ^ maltose and "^ dextrine are produced : —

3C,H,„05 -f H,0 = C„H,,0„ -f CeH.oOj.
Starch. Maltose. Dextrine.

The quantity of maltose produced at more elevated temperatures (above 63°)
steadily diminishes up to 75° when the action of diastase ceases [Berichte, 12,
949). These conditions are important in the manufacture of rum and the brewing
of beer. In the first case the mash obtained by the production of sugar at 60° is
cooled, then the maltose at once ferments and dextrine in consequence of the after-
action of the diastase, is first converted into grape sugar and then fermented ;
therefore, the fermentation of starch is almost a perfect one. In beer-brewing the
mash is boiled, to destroy the diastase, so that by the action of ferments only the
maltose suffers fermentation ; dextrine remains unaltered.

In preparing maltose, starch paste made by boiling with water is converted, at
60°, into sugar, by diastase, the solution then boiled, the filtrate concentrated to
a syrup and the maltose extracted by strong alcohol [Annalen, zzo, 209).

Maltose is usually obtained in the form of crystalline crusts, com-
• posed of hard, white needles, that lose their water of crystallization at
ioo°. In properties it closely approaches grape sugar. It is directly
fermented by yeast and reduces an alkaline copper solution, but to

MELITOSE, RAFFINOSE. ^H

only about ^ the amount effected by grape sugar; loo parts malt-
ose, judging from its reducing power, are equivalent to 6i parts grape
sugar, but in the case of Fehling's solution diluted four times, they
correspond to about 66.8 parts of the second {Annalen, 220, 220).
Its rotatory power is but slightly influenced by the temperature and
concentration of the solution, [a]„= +140.6° {Annalen, 220, 200).

Diastase does not exert any further change upon maltose ; when boiled with
dilute acids, it passes completely into grape sugar. Nitric acid oxidizes it to
saccharic acid, while chlorine changes it to malto-bionic acid, C, ^H^^O-^ ^. This
yields grape sugar and gluconic acid when it is heated with acids. Maltose and
milk sugar very probably possess the same structural formula [Berichte, 22,. 1941).

When heated with sodium acetate and acetic anhydride, it yields octoacet-maltose,
Ci2H,4(C2H30)|,Oii, which melts at 150-155°.

When boiled with lime water, it forms isosaccharin (p. 484). Phenylhydra-
zine converts it into phenylmaltosazone, CijH2„09(N2H.CjH,)2, melting at
82°.

Mycose, CjjHjjOu + ^H^O, Trehalose, occurs in several species of fungi,
in ergot of rye, and in the oriental Trehala. It is distinguished from cane sugar
by its ready solubility in alcohol, greater stability and stronger rolatory power.

Melebiose, CjjHjzOii) '^ produced, together wi'h ^/-fructose, in the hydroly-
sis of meletriose. Its osazone, Ci2H2o09.(N2H.C5H,)2, is soluble. Further
hydrolysis converts it into rf-glucose and galactose (Berichte, 22, 31 19; 23, 1438).

Rafhnose and melezitose are Trisaccharides.

Melitose, Raffinose, CiaH380ui + 5H2O, Melitriose. It occurs
in rather large quantity in Australian manna (varieties of Eucalyp-
tus), in the flour of cotton seeds, in small amounts in sugar beets, and
being more soluble than cane sugar, it accumulates in the molasses
in the sugar manufacture. From this it crystallizes out with the
sugar. Its crystals have peculiar terminal points, and show strong
rotatory power (Plus sugar).

Rafifinose is obtained from molasses, or by treating plus sugar with alcohol, in
which the raffinose dissolves with more difficulty than the sugar (Annalen, 232,
173). To determine the raffinose in the molasses and tailings, extract it with
methyl alcohol {Berichte, 19, 2872), then polarize and invert, or determine the
amount of mucic acid obtained by oxidizing the raffinose with HNO3 [Berichte,
19, 3H6).

It crystallizes in needles, more soluble in water and lessin alcohol
than cane sugar. It dissolves quite readily in methyl alcohol. It
loses its water of crystallization in a vacuum and when warmed. It
is more strongly dextro-rotatory than cane sugar : (a)„ = 104°. It
does not reduce Fehling's solution, but is easily fermented by yeast.

By hydrolysis it yields fructose and melibiose [Berichle, 23, Ref. 103). The
determination of its molecular weight by the method of Raoult showed it to be a
triose {Berichte, 21, 1569).

Melezitose, C, gHgjOj e -f ^Hfi, occurs in the juice of Fimts Larix, and
resembles cane sugar very much, his distinguished from the latter by its greater
rotatory power and in not being s6 sweet to the taste. It melts at 148° when anhy-
drous. It is also a triose [Berichte, 22, Ref. 759).

512 ORGANIC CHEMISTRY.

3. POLYSACCHARIDES.

It is very probable that the polysaccharides having the empirical
formula QHioOs, really possess a much higher molecular weight,
(CsHioOs)^. They differ much more from the hexoses than the di-
and tri-saccharides. They are, as a general thing, amorphous, dis-
solve with difficulty in water, and lack most of the chemical char-
acteristics of the hexoses. By hydrolysis, that is when boiling them
with dilute acids, or under the influence of ferments (p. 508), nearly
all are finally broken up into their component hexoses (see dextrine).
Their alcoholic nature is shown in their ability to form acetyl and
nitric esters.

Starch, Amylum, (C6H]o05)„ or CasHe^Ogi (p. 497), is found in
the cells of many plants, in the form of circular or elongated micro-
scopic granules, having an organized structure. The size of the
granules varies, in different plants, from 0.002-0.185 mm. Air
dried starch contains 10-20 per cent, of water ; dried over sulphuric
acid it retains some water which is only removed at ioo°- Starch
granules are insoluble in cold water and alcohol. When heated
with water they swell up at 50°, burst, partially dissolve and form
starch paste, which turns the plane of polarization to the right.
The soluble portion is called ^ranu/ose, the insoluble, starch cellulose.
Alcohol precipitates a white powder — soluble starch — from the
aqueous solution. The blue coloration produced by iodine is char-
acteristic of starch, both the soluble variety and that contained in
the granules {Berichte, 20, 694). Heat discharges the coloration,
but it reappears on cooling.

Boiling dilute acids convert starch into dextrine and (/-glucose.
When heated from 160-200° it changes to dextrine. Malt diastase
changes it to dextrine and maltose.

Concentrated sulphuric acid combines with starch, yielding a compound which
forms salts with bases. Heated wiih acetic acid we get the triacetyl derivative,
CgH ,0^(0 CjH jOjj, an amorphous mass, which regenerates starch when treated
with alkalies. Concentrated nitric acid produces nitrates.

Other starch-like compounds are : —

Paramylum, CjHjdO,, which occurs in form of white grains in the infusoria
Euglena viridts. It resembles common starch, but is not colored by iodine, and
is soluble in polassium hydroxide.

Lichenine, C^H, ^Oj, moss-starch, occurs in many lichens, and in Iceland moss
{^Cetraria islandicd), from which it may be extracted by water. The solution
becomes gelatinous, dries to a hard mass, and on treatment with boiling water
again forms a jelly. Iodine imparts a dirty blue color to it. It yields dextrose
when boiled with dilute acids.

Inulin is found in the roots of dahlia, in chicory, and in many Compositae (like
Inula Helinium) ; it is a white powder which dissolves in boiling waier, forming
a clear solution. Iodine gives it a yellow color. When boiled with water it is
completely changed to fruit sugar.

POLYSACCHARIDES. 5 1 3

Glycogen, CgHjoOj, animal starch, occurs in the liver of mammals and is a
reealy powder, which is precipitated from solution by alcohol ; it forms a paste
with colli water, and on heating is dissolved in it. Iodine imparts a reddish-brown
color to it. Boiling with dilute acids causes it to revert to dextrose, and ferments
change it to maltose.

The Gums, (CeHioOj)^. These are an)orphous,|ransparent sub-
stances widely disseminated in plants ; they form sticky masses with
water and are precipitated by alcohol. They are odorless and
tasteless. Some of them yield clear solutions with water, while
others swell up in that menstruum and will not filter through paper.
The first are called the real gums and the second vegetable mucilages.
Nitric acid oxidizes them to mucic and oxalic acids.

Dextrine. By this name are understood substances, readily
soluble in water and precipitated by alcohol ; they appear as by-
products in the conversion of starch into dextrine, e.g., heating
starch alone from 170-200°, or by heating it with dilute sulphuric
acid. Different modifications arise in this treatment ; amylo-
dextrine, erythrodextrine, achrodextrine ; they have received little
study. They are gummy, amorphous masses, whose aqueous solu-
tions are dextro-rotatory, hence the name dextrine. They do not
reduce Fehling's solution, even on boiling, and are incapable of
direct fermentation ; in the presence of diastase, however, they can
be fermented by yeast (p. 510). They are then converted into
^-glucose. They yield the same product when boiled with dilute
acids. r

Dextrine is prepared commercially by moistening starch with two per cent,
nitric acid, allowing it to dry in the air, and then heating it to 1 10°. It is em-
ployed as a substitute for gum {Berichte, 23, 2104).

Arabin exudes from many plants, and solidifies to a transparent, glassy,
amorphous mass, which dissolves in water to a clear solution. Gum arable or
gum Senegal consists of the potassium and calcium salts of arable acid. The
latter can be obtained pure by adding hydrochloric acid and alcohol to the solu-
tion. It is then precipitated as a white, amorphous mass, which becomes glassy
at 100°, and possesses the composition (C5Hi|,05)2 + H2O. It forms com-
pounds with nearly all the bases; these dissolve readily in water.

Some gum varieties, e.g., gum-arabic, yield galactose in considerable quantity
when boiled with dilute sulphuric acid; and with nitric acid they are converted
into mucic acid; others (like cherry gum) are transformed on boiling with sul-
phuric acid into arabinose, Cfi^f);, (p. 483), and into oxalic acid, not mucic acid,
by nitric acid. The gum, extracted from beechwood by alkalies and precipitation
with acids, is converted into xylose (p. 483) by hydrolytic decomposition.

Bassorin, vegetable gum, constitutes the chief ingredient of gum tragacanth,
Bassora gum, and of cherry and plum gums (which last also contain arabin). It
swells up in water, forming a mucilaginous liquid, which cannot be filtered; it
dissolves very readily in alkalies.

43

S.I 4 ORGANIC CHEMISTRY.

Cellulose, QaHjoOio, wood fibre, lignose, fornis the principal
ingredient of the cell membranes of all plants, and exhibits an
organized structure. To obtain it pure, plant fibre, or better,
wadding, is treated successively with dilute potash, dilute hydro-
chloric acid, water, alcohol and ether, to remove all admixtures
(incrusting substances). Cellulose remains then as a white, amor-
phous mass. Fine, so-called Swedish, filter paper consists almost
entirely of pure cellulose.

Cellulose is insoluble in most of the usual solvents, but dissolves
without change in an ammoniacal copper solution. Acids, various
salts of the alkalies and sugar precipitate it as a gelatinous mass
from such a solution. After washing with alcohol it is a white,
amorphous powder. Cellulose swells up in concentrated sulphuric
acid and dissolves, yielding a paste from which water precipitates
a starch-like compound (amyloid), which is colored blue by iodine.
After the acid has acted for some time the cellulose dissolves to
form dextrine, which passes into grape sugar, when the solution is
diluted, with water and then boiled.

So-called parchment paper (vegetable parchment) is prepared by
immersing unsized filter paper in sulphuric acid (diluted Y^ with
water) and then washing it with water. It is very similar to ordi-
nary parchment, and is largely employed.

Hexacet-cellulose, Ci^Hj ^0^(0.021130)5, is obtained by heating cellulose
(cotton) with acetic anhydride to 180°. It is an amorphous mass, soluble in con-
centrated acetic acid.

Cold, concentrated nitric acid, or what is better, a mixture of
nitric and sulphuric acids, converts cellulose or cotton into esters
or so-called nitro-celluloses. That these compounds are not nitro-
derivatives, but true esters, is manifest, when we consider that upon
treatment with alkalies they yield cellulose and nitric acid (p. 454).
Alkaline sulphides and ferrous chloride also regenerate cellulose,
the nitrogen escaping as ammonia or nitric oxide. The latter
only is evolved by iron sulphate in a concentrated hydrochloric
acid solution {Berichte, 13, 172).

The resulting products exhibit varying properties, depending upon their method
of formition. Pure cotton dipped for a period of 3-10 minutes into a mixture of
iHNOj and 2-3H2SO4, then carefully washed with water, gives gun cotton
(pyroxylin). This is insoluble in alcohol and ether or even in a mixture of the two.
It explodes violently if fired in an enclosed space, either by a blow or percussion.
It burns energetically when ignited in the air, but does not explode. Cotton
exposed for some time to the action of a warm mixture of 20 parts pulverized
nitre and 30 parts concentrated sulphuric acid becomes soluble pyroxylin, which
dissolves in ether containing a little alcohol. The solution, termed collodion,
leaves the pyroxylin, on evaporation, in the form of a thin, transparent film, not
soluble in water. It is employed in covering wounds and in photography.

DERIVATIVES OF CLOSED CHAINS. 515

In composition gun cotton is cellulose hexanitrate, Ci2H,^(0.N0,').0. ,
whereas the pyroxylin, soluble in ether and alco'iol, is essentially a tetra nitrate,
Cj2Hi^(O.N02)406,and a penta-nitrate, Ci2K,5(O.N02)50. (Beric/ite, 13',
1861.

Collodion dissolved in nitroglycerol (equal parts), yields explosive gelatine or
smokeless powder.

DERIVATIVES OF CLOSED CHAINS.
I. Polymethylene Compounds.

All the compounds considered in the preceding pages, in other
words, the so-called /«//>» derivatives, contain open, not closed carbon
chains, in which terminal and intermediate carbon atoms can be
distinguished very readily (p. 42). The numerous derivatives of
the benzene class, on the other hand, possess throughout a similar
and hence supposed closed carbon chain, made up of six carbon
atoms. Preceding the very stable benzene nucleus is a class of
compounds discovered in recent years, in which we have closed
chains. As examples we may mention trimethylene, tetra-
methylene and pentamethylene : —

/CH, CH^— CH, .CH,-CH,

ch/| I I ch/ I \

^CH^ CH,-CH, \CH,— CH,

Trimethylene. Tetramethylene. Pentamethylene.

CjHs. C^Hg. CjHk,.

In these closed rings or chains of symmetrically combined
C-atoms, the latter are all alike, so that isomerides are only possible
by the introduction of two or several substituting groups. These
parent substances and their derivatives have the same general form-
ula, CnXan, as the olefines and the other unsaturated compounds of ^
the same series ; the latter, however, are chiefly distinguished by -
their great additive power (p. 81). Indeed, the trimethylene
derivatives can, by energetic action, absorb bromine and HBr (but
not H, or I^) : the tetra- and pentamethylene compounds, on the
other hand, attach themselves fully to the hexahydro-benzene de-
rivatives.

The absence of " double linkage " in the polymethylene derivatives is very
evident from the fact that they cannot be oxidized by potassium permanganate.
An alkaline solution of the latter is not decolorized even upon standing for long
periods (p. 82) (Baeycr, Armalen, 245, 146). Consult A. Baeyer, Berichte, 18,
2278; Sachse, Berichte, 23, 1363, for stereochemical views relating to the poly-
methylene rings.

5l6 ORGANIC CHEMISTRY.

I. TRIMETHYLENE GROUP.

Trimethylehe, CsHg (see above), was first obtained by heat-
ing trimethylene bromide (p. 102) with metallic sodium {Preund,
1882) :—

yCHgBr .CHg

CH / + 2Na = CH / I + 2NaBr.

^CHjBr ^CHj,

It is more easily produced by the action of alcohol and zinc dust {Berichte,
■2,0, Ref. 706; 21, 1282).

It is a gas, like its isomeride, propylene. It differs from
this, in that it unites with difficulty with bromine and hydriodic
acid — forming trimethylene bromide and normal propyl iodide.
To account for this we assume that the closed ring has been
broken. Unlike the olefines it is not oxidized by potassium per-
manganate.

Experiments have been made to prepare trimethylene alcohol by acting upon
o-dichlorhydrin with metallic sodium. The product, however, was allyl. alcohol.

Carboxyl-derivatives of trimethylene are produced
(1) From raalonic ester, acetic ester and analogous compounds by
the action of alkylen bromides and sodium alcoholate (2 molecules)
(Perkin, 1S84) (Anna/en, 256, 193; Berichte, 21, 2693): —

CH^Br .COjR *7^\ CO^R

I +CH/ = )C( + 2HBr.

CH,Br \C0,R \^ ~^^^

Malonlc Ester.

a-Trimethylene-dicarboxylic Ester.

(2) By heating the addition products of diazo-acetic esters and
acrylic esters, when two nitrogen atoms split off (p. 375) (Cur-
tius) : —

I '^NjrCH.COjR = | ^'^CH.COjR + N,.

ROaC— CH / R.OjCCH ^

Acryl-diazo-acetic Ester. Trimethylene-dlcarboxylic Ester.

Fumaric ester, C2H2(C02R)2, yields trimethylene-tricarboxylic ester, and cin-
namic ester yields phenyltrimethylene-tricarboxylic ester, etc., when exposed to
like treatment {Berichte, 23, 701). /CHj

Trimethylene-carboxylic Acid, CHg^ | , isomeric with vinylacetic

^CH.CO^H
acid (isocrotonic acid, p. 238), is formed from a-dicarboxylic acid by heating it
to 160°. Carbon dioxide is eliminated. It is an oil with faint odor and boils at
190°. It does not unite with bromine, like the isomeric crotonic acids (p. 238).
Its ethyl eiter, C^HjOj.CjHj, from the silver salt and ethyl iodide, boils at
133°. It cannot take up bromine.

TRICARBOXYLIC ACIDS. 517

DICARBOXYLIC ACIDS.

a-Trimethylene-dicarboxylic Acid, CHj^; | , is isomeric with hypo-

Ihetical vinyl malonic acid, C2H3.CH(C02H)2, or Vinaconic Add [Anna/en, 227,
25). lis diethyl ester (see above) is formed from ethylene bromide and malonic
ester. Butan-tetracarboxylic ester is formed at the same time by the aclion of
ethylene bromide upon two molecules of malonic ester. The diethyl ester is an
oil that boils at 207°- The free acid melts at 140° and above 160° decomposes
into CO2 and trimethylene carboxylic acid (with butyro-lactone). Digestion with
dilute sulphuric acid converts it into isomeric butyrolactone carboxylic acid
(p. 468). It, however, combines wilh HBr, disrupting the trimethylene ring and
forming bromethyl malonic acid fp. 418). It unites in an analogous manner with
bromine and forms dibrom-ethyl-malonic acid, which decomposes and melts at
100-110° yBerichie, 18, 3414). These reactions indicate that the acid is vinyl-
malonic acid. However, it cannot be further alkylized, and, unlike the mono-
alkylic-malonic acids, it is not attacked by nitric acid, potassium permanganate — or
even sodium amalgam (^Berichte, 23, 704). This behavior argues in favor of its
trimethylene character. , CH.COjH

/3- or (i, 2)-Trimethylene-dicarboxylic Acid, CHjcf | , is obtained

\ CH.COjH
(together with its anhydride) from a-trimethylene tricarboxylic acid, by healing the
latter to 190°, when CO2 splits ofif, and also from /3-trimethylene telracarboxylic acid
by a similar loss of aCO,. It crystallizes in vitreous prisms and melts at 139°- It
is not affected by either potassium permanganate or sodium amalgam. Its anhy-
dride, C3H^(CO).20, forms needles, melting at 59° and unites with water at 140°,
regenerating the acid [Beric/iU, 23, Ref. 241).

7-Trimethylene-dicarboxylic Acid, 0,11^(00211)2. Its dimethyl ester is
formed (together with the ester of glutaconic acid, p. 428) upon distilling acryl-
diazo-acetic ester. It boils at 2io° under a pressure of 720° mm. The free acid
melts at 175°, distils unaltered, and does not form an anhydride. Potassium per-
manganate and sodium amalgam do not affect it.

The y-acid appears to have the same structural formula as the /3-acid. It is,
therefore, assumed that they are stereochemical isomerides. As the /3-acid readily
yieUls an anhydride, it is called the maleinoid-, and the y-?iciAfumaroid (i, 2)-tri-
methylene dicarboxylic acid (p. 424) [Berichte, 23, 702).

TRICARBOXYLIC ACIDS.

/

C(C02H)2

a-Trimethylene-tricarboxylic Acid, CH„( | . The trimethyl ester

\CH.CO2.H
is obtained in a manner analogous to that employed in the case of the dicarboxylic
ester. It is an agreeably smelling liquid, which boils at 276° {Berichle, 17, 1 187).
The same ester results from the union of malonic ester and a-bromacrylic ester. It
is, therefore, probably CH2:C(C02H).CH(C02H)2 {Berichte, 20, Ref. 140,258).
The free acid crystallizes in shining needles and melts at 184°, decomposing into
CO2 and ;3-trimelhylene-dicarboxylic acid. CH.COjH

Sym. (1,2, 3)-Trimethylene-tricarboxylic Acid, (C02H)2CH(_ | ,

^ ^ \CH.CO2H

is formed from a-tetracarboxylic acid by splitting off carbon dioxide. It melts

about 150° [Berickte, 17, 1652). When fumaric-diazoacetic ester is heated,

5l8 ORGANIC CHEMISTRY,

it yields the trimethyl ester of a trimethylene-tricarboxylic acid that is identical
with the preceding. It is not changed by potassium permanganate or sodium
amilgam. It melts at 220°. If it is heated to 240°, it loses water and

becomes the anhydride, C,H3(C02H)/pQ>0, melting at 187°. It boils at 265°
{•JS mm.) {BericAie, 21, 2641). ^

TETRACARBOXYLIC ACIDS.

CH.COjH
a-Trimethylene-tetracarboxylic Acid, (COjHj^C:; | . Its tetra-

^ CH.COjH
ethyl ester is obtained from milonic and dibromsuccinic esters. It boils at 246°
' The free acid melts at 95-100° C, decomposing into COj and symmetrical (1,2, 3).
tricarboxylic aciil. , C(C02H)2

;8-Trimethylene-tetracarboxylic Acid, CHj^ | . Its tetracthyl

^ C(CO,H),
ester is produced by the action of bromine upon disodium propan-tetracarboxylic
ester (p. 482) : —

CNa(C02R)2 C(CO,R),

CH/ +2Br = CH/| + 2NaBr.

\CNa(CO,R), \C(CO,R),

It melts at 43°, and under a pressure of 12 mm. boils at 187°.

The free acid decomposes into 2CO2 and /3-trimethylene dicarboxylic acid [Be'
richie, 23, Ref. 241) when heated above 200° C.

ICETONIC ACIDS.

Aceto-trimethylene Carboxylic Acid, CH3CO.C5H^.C02H. Its ester is
formed when ethylene bromide and sodium ethylate (2 molecules) act upon aceto-
acetic ester : —

CH^Br .CO.CH3 CHj. .CO.CH3

I + CH / = I )C( + 2HBr.

CH^Br ^CO^R CH./ ^CO^R

Diaceto-adipic ester (p. 438) results simultaneously through the action of C^H^Br,
upon two molecules of sodium aceto acetic ester.

The ethyl ester is a faintly-smelling liquid, boiling about 195°- As a ketone, it
combines with phenylhydrazine. HBr induces the rupture of the trimelhylene ring
and brom-ethyl acetoacetic ester results (p. 340) [Berichte, 16, 2565). The free
acid is a thick oil, which decomposes at 200° into CO2 and aceto-trimethylene,
CH3.CO3.C3H5, which boils at 113° [Berichte, Z2, Rcf. 502, 572; 22, i2lo).

Benzoyltrimethylene Carboxylic Acid, CjHj.CO CjH^.COjH, is pro-
duced, like the preceding, from lienzoyl-acetic e«ter. It forms large prisms, melts
at 149°, and decomposes into COj and benzoyl-trimethylene, CjHj.CO.CjHj.
An oil,-boiling at 239°. It forms an oxime with hydroxylamine [Berichte, ig,
2S6s)._

Boiling alkalies do not decompose benzoyl- and aceto-trimethylene carboxylic
acids. Herein they differ from allyl aceto-acetic and allyl-benzoyl acetic acids.
In a similar manner paranitro-benzoyl acetic ester yields paranitrobenzoyl tri-
methylene tricarboxylic ester [Berichte, 18, 958).

TETRAMETHYLENE DERIVATIVES. 519

2. TETRAMETHYLENE DERIVATIVES.

Tetramethylene derivatives (p. 515) are obtained by acting upon malonic ester
with trimethylene bromide and sodium alcoholate (2 molecules) (Perkin) : —

^"^^XCH^Br + CH,(CO,R), = CH./^^XqcOaR)^ + 2HBr.

Tetramethylene-carboxylic Acid, C^Hj.C02H, isomeric witb allyl-acetic
acid, is formed from the dicarboxylic acid by withdrawal of COj. It is an oil,
which boils at 194°, and has an odor like that of a fatty acid.

Not tetramethylene, C^Hg, but Ditetramethylene Ketone, C^Hj.CO.C^H,,
is formed by distilling its lime salt. This is a liquid, with an odor like that of pep-
permint. It boils at 205° (Berichte, ig, 3113).

(2-Tetramethylene-dicarboxylic Acid, C ^U ^{CO ^Yi) ^. Its* diethyl ester
(isomeric with allyl malonic ester, p. 430) is formed (together with pentan-tetra-
carboxylic ester, p. 482) from trimethylene bromide and malonic ester {^Berichte,
ai, 2693). It is an oil with camphor-like odor, and boils at 224° (Berichte, 16,
1787). The free acid dissolves easily in ether and benzene, but not in chloroform
and benzine; it crystallizes in shining prisms, and melts at 155°, decomposing into
the monocarboxylic acid and COj. Cllj — CH.COjH

/3-Tetramethylene Dicarboxylic Acid, | I , results upon

CHj— CH.COjH
heating tetracarboxylic acid (see below) to 180° C. with water. It splits off aCOj
groups. It is crystalline and melts at 130° C. At 300° it loses water and becomes
the anhydride C4H5(CO)20, melting at TJ°' {Beric/Ue, 19, 2042).

The third Tetramethylene Dicarboxylic Acid, (C02H)Ch/^[|2\ch.

CO^H, appears to be tetrylene dicarboxylic acid, whose ester results from the
action of a-chlorpropionic ester and sodium ethylate. It boils above 230° [Annalen,
208, 333). Its free acid is crystalline, melts at 171° and sublimes in needles.
The acid and the ester do not combine with nascent hydrogen, HBr or bromine.
Consult Berichte, 23, Ref. 432 for its anhydride derivatives.

a-Tetramethylene Tetracarboxylic Acid, | | .Its ethyl ester

CH,.C(C0,H),
is produced by the action of bromine (as with /3 trimethylene tetracarboxylic ester)
upon butan-tetracarboxylic ester (its disodium compound) : —

CH,.CNa(C0„R)2 CH^— C(C02R)2

I +Br,= I I +2NaBr.

CH2.CNa(C02R)2 CH^— C(C02R)2

The free acid is crystalline, melts at 145-150° C, and decomposes into 2C0j
and /3 tetramethylene dicarboxylic acid {Berichte, 19, 2041).

,3- Tetramethylene Tetracarboxylic Acid, [CO ^Yi.) ^Q.(^^'yC[CO ..Wj ^.

Its tetraethyl ester has been obtained from the disodium dicarboxyl-glutaric ester
by means of methylene iodide {Berichte, 23, Ref. 240).

S20 ORGANIC CHEMISTRY.

KETONIC ACIDS.

When trimethylene bromide acts upon acetoacetic ester the product is not the
analogous —

Aceto-tetra-methylene Carboxylic Ester, CH /^][^2\C(^^q2^^s.

but the ester of an isomeric acid, which probably represents the carboxylic acid of
the anhydride of acetobufyl alcohol, as it breaks up, when distilled, into COg and
that anhydride (p. 322). CjHjBrj also acts analogously upon benzoyl-aceto-acetic
ester and acetone dicarboxylic ester (Berichte, ig, 2557; 21, 736).

Diaceto.tetramethylene Dicarboxylic Acid, (CHjCOyjCiH^fCOjH)^,
is a true diketonic acid. Its diethyl ester is produced in the action of bromine
upon the disodium compound of diaceto-adipic ester (see above) : —

CH,.CNa/'™-^i^» CH^-C/^R-^H

NCO3R

+ Br,

\CO.R ^,NaBr.
C— CO,R

CH,- ^CO.CH,

It is a liquid, which is colored a violet red by ferric chloride. The free acid
from it crystallizes with 2H2O, which it loses at 80°. When anhydrous the acid
melts, with decomposition, at 210° {Berichte, ig, 2048).

3. PENTAMETHYLENE DERIVATIVES.

, CH2-C(C0,H),
Pentamethylene-tetra-carboxylic Acid, CHj^ | . Bro-

\CH2-C(CO,H),-
mine converts disodium pentan-tetra-carboxylic ester into its tetraethyl ester
{Berichte, 18, 3246) : —

^\CH,.CNa(CO,R), ^ ^ '\CH,.C(CO,R),

The free acid, from the oily ester, decomposes when heated to 200-220° into
2CO2 and Pentamethylene-dicarboxylic Acid, C5Hj(C02H)2, crystallizing
in warty masses, melting at 160°. At 300° it yields water and the anhydride,
C5Hj(COJ20, melting about 65° {Berichte, 18, 3251).
CH^.GHjv

Ketopentamethylene, | ) CO, may be obtained by distilling calcium

CH,.CH/
adipate. If two of its O-atoms be replaced by two chlorine atoms, and further
acted upon with nascent hydrogen the product will be Pentamethylene, C5H1 „.
This is a liquid boiling at 30-31° (J. Wislicenus).

Derivatives , of (l, 2)- and (l, 3)-diketo pentamethylene have been prepared
by oxidizing orthoamidophenol and pj rocatechol with chlorine. The'six-mem-
bered' benzene ring is changed to th,e 'five-membered' pentamethylene ring
(Zinclce, Berichte, 21, 2718; 23, 813, 2200). The naphthalene ring by similar
treatment yields the indene ring.

DiUeto-pentamethylene derivatives have been prepared by the action of chldrine
upon alkaline solutions of phenol and chloranilic acid (Hantzsch, Berichte Z2, 1238

FURFURANE, THIOPHENE AND PYRROL DERIVATIVES. 52I

and 2841). Consult Berichte, 22, 2827; 23, 1478 for the transformations of
pentamethylene compounds into derivatives of benzene, pyridine and thiophene
{Berichte 22, 2827 ; 23, 1478).

Leuconic Acid, C5O5 -|- SH2O, and Croconic Acid, C5O5H2, keto-deriva-
tives of pentamethylene, will be discussed together with the triquinoline deriva-
tives.

Methronic acid, carbopyrotritartaiic acid and their compounds are considered

CH = CH
derivatives of hypothetical ketopentene, | ^CO, tetrylone.

CH,— CH /

Hexamethylene, Q^Yi.^^ = ZYi^(^^ _^^^Cii^, is described under

the benzene derivatives as hexahydrobenzene (benzene hydride).

A Heptamethylene derivative, C,Hi4, seems to have been obtained from
diaceto-adiplc ester (Berichte, ig, 2052).

FURFURANE, THIOPHENE AND PYRROL DERIVATIVES.

The polymethylene closed chains consist of carbon atoms only ;
but there are those which in addition to the C-atoms also contain
atoms of other polyvalent elements (oxygen, sulphur and nitrogen).
Closed chains of this class are numerous among the fatty bodies,
e. g., the anhydrides of the dicarboxylic acids (succinic anhydride,

CH^CO
p. 41 2) succinimide, | /NH (p. 412), parabanic acid, the

CH.CO/
derivatives of cyanuric acid and melamine (p. 290), etc., etc. In
all of them 2 CO are usually united by O, S or N, and the com-
pounds are very unstable and change rapidly to the normal open
chains. The chain of the ^--lactone contains but one CO-group,

Q.^iC^^^~7P^^Q,0 (p. 351), and is more stable. Furfurane,

C^H^O, Thiophene, C4H4S, and Pyrrol, C4H,(NH), consist ef
closed chains in which the linking is even firmer than in the deriva-
tives mentioned. These bodies attach themselves to the benzene
series ; their constitution is very probably represented by the fol-
lowing structural formulas : —

CH = CH^ CH = CH, CH = CH

I >0 I /S I >NH.

CH = CH^ CH = Ch/ CH = CH^

Furfurane. Thiophene. Pyrrol.

In accordance with these formulas the three parent substances
and their derivatives exhibit many striking analogies in their entire
deportment. Thus furfurane, thiophene and pyrrol yield bluish
44

522 ORGANIC CHEMISTRY.

violet dyestuffs with isatin and sulphuric acid, and compounds hav-
ing a violet red color, when acted upon with phenanthraquinone
and sulphuric acid. Again, these compounds, and all those
obtained from them, exhibit a striking and astonishing similarity
to benzene. This is especially true of thiophene. All the peculiar
reactions of benzene derivatives; those which distinguish the latter
from the fat-bodies, are shown by furfurane, pyrrol and thiophene.
Thus, the halogens produce substitution derivatives and not
additive compounds (as with the olefines). This would scarcely
be expected from the fact that double unions occur in furfurane,
etc., etc.

The synthetic methods, applied in the formation of furfurane, pyrrol and thio-
phene, correspond in every particular to the accepted structural formulas. All
three compounds are obtained from y-diketone derivatives, in which the atomic
group — CO.CH 2 .CH jCO — is present, by the separation of water and the linking of
the two carbonyl carbon atoms by O, S or N (p. 329). It may be assumed that
here the diketone form sustains a transposition into the unstable, unsaturated
dihydroxyl form (syntheses of Paal, Berichte, 17, 2757; 18, 367), etc.; —

CHj— CO— R CH = C(OH)— R CH = C(

I or I yields | >0(S or NH).

ch„— co— r ch = c(oh)— r ch = c(

\r

Analogous hydroxyl derivatives react in harmony with this view; thus, by with-
drawing water from mucic and isosaccharic acids furfurane dicarboxylic acid is
formed, and by distillation with BaS thiophene carboxylic acid is the product
(p. 534) :—

.CO^H
CH(OH)— CH(OH)— COjH CH = C(

I . yields I )0(or S) + 3H2O.

CH(OH)— CH(OH)— CO„H CH = C<

\CO2H

Diaceto-succinic acid (p. 437) yields dimethyl furfurane dicarboxylic acid and
ditnethylpyrrol dicarboxylic acid (syntheses of Knorr, Berichte, 17, 2863 ; 18,
299, etc.) :—

CH3.
CH3.CO.CH.CO2R >C = C.COjR

I yields (or NH)0( I + H^O.

CHj.CO.CH.COjR )C = C.CO2R

CH3/

CH3.CO.CHj
In a similar manner acetonyl-acetoacetic ester, | (p. 340),

CH3.CO.CH.CO2R
yields the dimethyl monocarboxylic acids, etc. Consult Berichte, zi, 2932, 3451
for other furfurane derivatives.

To distinguish the possible isomerides the replaceable hydrogen atoms, or the

THE FURFURANE GROUP.

523

C-atoms in furfurane, thiophene and pyrrol are designated by numbers as with
benzene : —

21 /3 a

CH = CH CH = CH,

I )0 or I \o.

CH = Ch/ CH = Ch/

' * /3' a'

The positions 1 and 4 are equal in value, also 2 and 3. The first are also
termed a-, the latter /3-positions. It is obvious that the mono-derivatives of fur-
furane, etc., can exist in two isomeric forms (a-derivatives and ^-derivatives).

I. THE FURFURANE GROUP.*

Furfurane, QH^O (see above), was formerly held to be tetrol-
phenol, C4H3.OH. It was first obtained by distilling barium pyro-
mucate (p. 526) with soda-lime : (QH3O.CO2H = QH^O -f COj).
It is present in the distillation products of pine wood. It is a
liquid, insoluble in water, has a peculiar odor, and boils at 32°.
Metallic sodium has no effect upon it, nor does it combine with
phenyldrazine. It yields dye substances with isatin and phenanthra-
quinone (see above). It reacts very violently with hydrochloric
acid, and forms a brown amorphous substance (like pyrrol red,
P- 539)- A. pine shaving moistened with hydrochloric acid, assumes
a green color when brought in contact with the vapors of furfurane.

Brominated derivatives can be obtained from brom-pyromucic acids, or by the
direct action of bromine upon furfurane. Other addition products result from
an excess of bromine.

ALKYLIZED FURFURANES.

Methyl Furfurane, C4H3(CH3)0, is in all probability jy/w«», which occurs
in pine tar oil. It boils at 63° [Berichte, 13, 881).

ffi-Dimethyl Furfurane, C4H2(CH3)20(i, 4), is formed by the distillation of
carbopyrotritartaric acid (p. 528), and has been directly synthesized from aceto-
nyl acetone upon heating it with ZnClj or P2O5 (p. 328). A mobile liquid with a
peculiar odor. It boils at 94°. It is resinified when heated with concentrated
mineral acids {Berichte, 20, 1085).

It regenerates acetonyl acetone when it is heated with dilute hydrochloric acid
to 170°.

a-Methyl-phenyl Furfurane, C^H^ \ r ^ \ 0(i.4).is produced from aceto-

CH3.CO.CH3 I. "-6^6 J

phenoneacetone, | , upon digesting it with acetic anliydride, or

CH3.CO.C3H5
hydrochloric acid, (Berichte, 17, 915 and 2759). It crystallizes from alcohol in
shining needles, melting at 42°. The compound boils at 235-240° C. Sodium,
in alcoholic solution, converts it into the tetrahydro-compound, CnHj^O.

Nitroethylene Furfurane, C4H30.CH:CH(N02). This results from the
condensation of furfurol, C4H3O.CHO, with nitroethane. It consists of yellow

* Compare " Das Furfuran, etc," von A. Bender, 1889.

524 ORGANIC CHEMISTRY.

needles, melting at 75° ( Berichte, 18, 1362). By nitration it passes into nitro-
fiirfurane-nitroethylene.

Butylene Furfurane, C^HjO.C^H,, has been obtained by tbe condensation
of furfural with isobutyric acid (see below). A liquid, boiling at 153° [Berichte,
17, 850).

Diphenyl Furfurane, Cfi^[Q.^'R^^^O, see Berichte, 21, 3057. Triphenyl
Furfurane, C^HfCgHj),©, see Berichte, 21, 2933. Tetraphenyl Furfurane,
0^(05115)^0, Lepidene, Berichte, 22, 2880.

ALCOHOLS.

Furfuryl Alcohol, CjHgOa = C4H3O.CHJOH (the monovalent group
CjHjO is called furfur-), results from- the action of sodium amalgam and acetic
acid upon the aldehyde furfurol, but more easily by treatment with aqueous caustic
potash [Berichte, 19, 2154). Furfurane carboxylic acid is produced at the same
time (2C4H3O.CHO + HjO = C^HjO.CHjOH + C^HjO.COjH). Ether
extracts it as a colorless syrup, whiph in drying becomes gummy. It is colored
green by hydrochloric acid.

Ethylfurfur-Carbinol, S^JI^^^CH.OH, results from the action of furfurol

and zinc ethide. It boils at l8o° (Berichte, 17, 1968).

ALDEHYDES AND KETONES.

a-Furfurol, CsH^Oj = QHsO.CHO, (1-4), the aldehyde of
furfuryl alcohol, or of pyromucic acid, is produced in the distilla-
tion of bran with dilute sulphuric acid, or of sugar, as well as most
carbohydrates and glucosides. When present in even the merest
traces it can be detected by the red coloration given by aniline
or xylidine {Berichte, 20, 541). It yields a violet coloration with
a-naphthol and sulphuric acid (JBerichie, 21, 2744).

Preparation. — Distil I part of. bran with i part sulphuric acid ; dilute with 3
parts of water. Throw out the furfurol from the distillate by the addition of com-
mon salt, and repeat the distillation [Annalen, 116, 257; 156, 198). The pro-
duct obtained on distilling algae with sulphuric acid consists chiefly of furfurol and
methyl furfurol [Berichte, 23, Ref. 154).

Furfurol is a colorless liquid with an aromatic odor. Its specific
gravity at 13° is 1.163. It boils at 162°. It is soluble in 12 parts
of water at 13°, and very soluble in alcohol. It becomes brown
on exposure to the air, and shows all the properties of an aldehyde.
It combines with bisulphites, passes into furfuryl alcohol under the
influence of sodium amalgam, and is changed to pyromucic acid
by argentic oxide, and to the alcohol and acid through the action
of caustic potash (this is similar to the behavior of the benzalde-
hydes). It yields furfuraldoxime, C4HsO.CH:N(OH) with hy-
droxylamine ; it melts at 89° and boils at 205° {Berichte, 23, 2336).
It unites similarly with phenylhydrazine, forming a hydrazone,
C4H30.CH:(N2H)C6H5, melting at 96°. Furthermore, furfurol mani-
fests all the condensation reactions of benzaldehyde (see below).
It combines with dimethylaniline to form a green dye-stuff, cor-
responding to malachite green.

AMIDE DERIVATIVES. 525

In furfurol the aldehyde group occupies the a-position. This is
evident from the fact that the furonic acid, obtained from it, can be
reduced to normal a-pimelic acid (p. 528).

a-Methyl Furfurol, C4H2(CH3)O.CHO, occurs together with furfurol in wood
oil. It can be isolated from this by fractional crystallization [Berichie, 22, 608).
It is also present in the product obtained by distilling varec with sulphuric acid
{Berichte, 22, Ref. 751). When rhamnose is distilled with sulphuric acid, it re-
sults, and may, therefore, be considered as the anhydride of rhamnose (^Berichte,
22, Ref. 752): —

CH(0H).CH(0H).CH3 CH=c/

I >0 + 2H,0.

CH=C

CH(OH).CH(OH).CHO CH=C.

^CHO

It is an oil, boiling at 184-186°. It may be oxidized to methyl pyromucic acid.
Alcohol and sulphuric acid color it green.

Furfurol condenses with fatty aldehydes and ketones, forming furfuryl-aldehydes
and ketones having unsaturated side-chains. As in the case of benzaldehyde this
reaction here proceeds with ease on digesting with sodium hydroxide (Berichte,
12, 2342). Thus acetaldehyde or paraldehyde reacts according to the equation: —

C4H3O.CHO + CH3.CHO = C^HjO.CHiCH.CHO, Furfur-acrolein.

Furfur-acrolein, CjHgO^, melts at 51° and boils above 200°. Propionic alde-
hyde yields Furfur-crotonaldehyde, C4H30.CH:C(CH3)CHO, which is an oil
with ethereal odor. With acetone, furfurol forms Furfur-acetone, C^HgO.CH:
CH.CO.CH3, etc.

When furfurane is exposed to the action of KCN in alcoholic solution, it suffers
a peculiar transposition into Furoin (like that of benzaldehyde to benzoin) : —

C4H3O.CO
2C,H30.CH0 = I , Furoin.

C4H3O.CH.OH

* Furoin, Ci^HjO^, is crystalline and melts at 135°- The oxygen of the air oxi-
dizes it, when in alkaline solution, to Furil, C-^^fii^= C^HjO.CO.CO.C^HjO, a
compound analogous to benzil. KCN decomposes furil into furfurol and the ester
of pyromucic ester [Berichte, 16, 658). When furil is digested with caustic potash
it becomes furilic acid (analogous to benzilic acid (see this).

Mixed furoins, e.g., Benzfuroin, C4H3.CO.CH(OH).CeH5, are produced,
like furoin from furfurol, by letting KCN act upon a mixture of furfurol and benz-
aldehyde.

AMIDE DERIVATIVES.

Furfurylamine, C^HjO.CH^.NHj, is obtained by reducing furfuro-nitrile,
C^HgO.CN (p. 526), and furfurol hydrazone (p. 524) with sodium amalgam. It
is a liquid, boiling at 146° [Berichte, 20, 399).

Furfuramide, {Q.^'R^Q))^^, results from the action of aqueous ammonia upon
furfurol (same as hy'drobenzamide from benzaldehyde, see this) : —

3C,H30.CHO + 2NH3=^*^g'^g;^g:^)CH.C,H30 + 3H,0.

526 ORGANIC CHEMISTRY.

' It is very soluble in alcohol and ether. It crystallizes in yellowish-colored
needles, melting at 117°. It has a neutral reaction, and does not combine with
acids. Acids and boiling water decompose it into furfurol and ammonia. If
heated to 120°, or if boiled with KOH, it undergoes a transposition (like that of
hydrobenzamide into amarine) into the isomeric base, Furfurin, Cj^Hi^NjOj,
melting at 116°, and forming salts with one equivalent of the acids. It is perfectly
analogous to amarine of the benzene series.

Benzene amido-compounds of varying composition are, produced by the union
of furfurol with anilines and aromatic diamines (l and 2 molecules of the same)
(Annalen, 201, 355). In this way, dye-stuffs, resembling rosaniline, have been
produced. Their salts show an intensely red color, e.^., furoxylidine, C4H3O.
CH(CjHj.NHj)2, and answer for the detection of furfurol {Berichte, 20, 541).

ACIDS.

a-Furfurane-carboxylic Acid, C5Hi03 = QH30.C02H,/'^''«-
mucic acid, is obtained by the oxidation of furfurol with silver oxide
or caustic potash, and in the distillation of mucic and isosaccharic
acids (p. 522); it, therefore, contains the carboxyl group in the
o-position.

To prepare pyromucic acid, distil about 30 grams of mucic acid from a retort
(Annalen, 165, 256). A better course is to let alcoholic caustic potash act upon
furfurol {Annalen, 165, 279).

Pyromucic acid is very soluble in hot water and alcohol. It crys-
tallizes in needles or leaflets, melting at 134°, and subliming at
100° C.

Its ethyl ester, C4H3O.CO2.C2H5, melts at 34° and boils at 210° C. Its chlor-
ide, C4H3O.COCI, obtained by distilling the acid with PCI5, boils at 170°. Am-
monia converts this into an amide, C^HjO.CO.NH^, which is changed into
furfuryl-nitrile, C4H3O.CN, by PCI3.

Bromine vapor converts pyromucic acid into a tetrabromide, C^HjOBr^.COjH,
which is oxidized to dibromsuccinic acid by chromic acid. Fumaric acid results
on evaporating pyromucic acid with bromine water (2 molecules). An excess of
bromine or chlorine water produces mucobromic acid, C4H2Br203, and muco-
chloric acid, C^^QXJd^ (p. 427).

a-Brom-pyromucic Acid, C^HjBrO.COjH (4 or a') is formed by heating the
tetrabromide, and by brominating pyromucic acid in glacial acetic acid solution.
It consists of pearly leaflets, melting at 184° {Berichte, ig, Ref. 241). (3-Brom-
pyromucic Acid, C4,H2BrO.C02H, from the two dibrompyromucic acids and
zinc, melts at 129°.

Two Dibrompyromucic Acids, CjHBrj.COjH, have been obtained from
pyromucic tetrabromide by means of alcoholic soda. The ;8/3'-acid melts at 192°,
the /3a'-acid at 168° {Berichte, 17, 1759).

Nitropyromucic Acid, C^H2(N02)O.C02H, is formed by nitrating furfurane
dicarboxylic acid with a mixture of nitric and sulphuric acids, and by oxidizing
nitroethylene-nitrofurfurane (p. 523). It crystallizes from water in bright yellow
plates, melting at 183° {Berichte, 18, 1362).

Isopyromucic Acid, CjHjOj, apparently does not exist {Berichte, 23, Ref.
154)-

FURFUR- ACRYLIC ACID. 527

Methyl Pyromucic Acid, C5HgfCH3)03, has been obtained by the oxidation
of methyl furfural. It melts at 109° [Berichte, 22, 608). Bromine water converts
it into aceto-acrylic acid [Berichte, 23, 452).

Methyl Furfurane Acetic Acid, CjHjOj^SJ;'' qq ti Sylvan-acetic acid, has

been obtained by the condensation of glyoxal with aceto-acetic ester, etc. It melts
at 137° {Berichie, 21, Ref. 636).

aa-Dimethyl Furfurane-/3 carboxylic Acid, Pyrotritartaric Acid, CjHjOj
= €411(0113)20. COjH {Berickte, 20, 1074), Uvinic Acid, was first obtained
from tartaric acid (with pyroracemic) by distillation. It can also be produced
from pyroracemic acid by protracted boiling with baryta water or sodium acetate,
etc. It has been synthetically prepared (its ethyl ester) by the action of fuming
hydrochloric acid upon acetonyl aceto-acetic ester (Berichte, 17, 2765). It also
results from carbopyrotritartaric acid and from methronic acid (p. 528) by the
splitting-oiT of carbon dioxide. This occurs when the acid is heated beyond its
melting point. This is the best method for the obtainment of uvinic acid.

Pyrotritartaric acid dissolves with difficulty even in hot water (in 400 parts),
from which it crystallizes in needles, melting at 135° C. It sublimes readily and
is quite volatile with steam. When heated to 150-160° with steam it breaks up
into carbon dioxide and acetonyl acetone (p. 328). Rapidly distilled, it decom-
poses into carbon dioxide and a-dimethyl furfurane. See Berichte, 20, 1077, for
brompyrotritartaric acid. /PH \

aa-Methylphenylfurfurane-carboxylic Acid, C^HIpTr jO.CO^H. Its

ethyl ester is produced by the action of hydrochloric acid upon acetophenon-aceto-

CeH5.CO.CH,
acetic ester, | (p. 522). The free acid, obtained by saponifica-

CH3.CO.CH.CO2R
tion, melts at 181°, and upon boiling with dilute sulphuric acid yields methyl-
phenylfurfurane (p. 524) (Berichte, 17, 2764).

Furfurane acids, with unsaturated side chains, are produced in the condensation
of furfurol and fatty acids, on heating it with the anhydrides and sodium salts of the
fatty acids. This is analogous to the formation of cinnamic acid (see this) from
benzaldehyde. Furfur-acrylic acid results on heating furfurane with acetic anhydride
and sodium acetate : —

C4H3O.CHO -\- CHj.COjNa = C4H30.CH:CH.C02Na -|- Yif).
Furfurane. Furfur-acrylic Acid.

Furfur-acrylic Acid, C7Hg03. This acid is also formed on oxidizing furfur-
acroleln with silver oxide; furfur-malonic acid also yields it {Berichte, 21, 1081).
It dissolves with difficulty in water, crystallizes in long needles, has an odor like
that of cinnamon, and melts at 135°. When it is heated with hydrochloric acid it
becomes acetone-diacetic acid. Sodium amalgam converts it into

Furfur-propionic Acid, CjH30.CHj.CHj,C02H, melting at 51°. Bromine
disrupts the furfurane ring in this compound, and the product is the aldehyde of
furonic acid (Berichte, 10, 695) : —

CH = CH. CH— CHO

I )0 -f O = II

CH = c( CH— CO.CH2.CH5,.C02H,

528 ORGANIC CHEMISTRY.

CH.CO,H
which silver oxide converts into furonic acid, CjHgOj :

Needles, melting at 1 80°. Sodium amalgam changes furonic acid to hydrofuronic
acid, CjHjjO^, which passes into normal pimelic acid, C5Hj(|(C02H)2 (p. 421), on
heating it with hydriodic acid and phosphorus [Berichte, 11, 1358).

Furfur-angelic Acid, CgHijOg = C^f).Q:Z(^^-^^^' from furfurol and

butyric acid (see above), melts at 88°, and passes into the corresponding 'Furfur-
valeric Acid under the influence of sodium amalgam.

DICARBOXYLIC ACIDS.

a-Furfurane Dicarboxylic Acid, CgH^Oj = C^fi{CO.^i{)^, dehydromucic
acid, is produced by heating mucic acid to 100° with hydrochloric and hydro-
bromic acid (p. 522). It dissolves with difficulty in water, crystallizes in needles,
and when heated does not melt but breaks up into carbon dioxide and pyromiicic
acid.

a-Dimethylfurfurane-^-dicarboxylic Acid, CgHgOj = €^(0113)20(00211)2,
carbopyrotritartaric acid, results upon boiling diacetsuccinic ester (p. 437) with
dilute sulphuric acid. When the ester is heated alone, or is acted upon by con-
centrated hydrochloric acid, the primary ester, CgHj05.C2H5, is produced, but if
allowed to stand with sulphuric acid, the diethyl ester, 0311505(02115)2 (Berichte,
17, 2864), is the product. Carbopyrotritartaric acid crystallizes from hot water
in minute needles, melting at 231°, and at higher temperatures breaks up into
carbon dioxide and pyrotritartaric acid.

Methronic Acid, OgHgOg = 0^(0113)20(00211)2, is isomeric with carbopyro-
tritartaric acid. It is produced by digesting aceto-acetic ester with sodium succin-
ate and acetic anhydride (Fittig, Berichte, 18, 3410). By similar action, aceto-
acetic ester and pyrotartaric acid yield methyl methronic acid, and benzoyl-acetic '
ester and succinic acid form phenylmethronic s.aA{Berichte,i\, 2134). Methronic
acid is more soluble in water and melts at 204°. At higher temperatures it also
decomposes into carbon dioxide and pyrotritartaric acid. It is, therefore, very
probable that methronic acid and carbopyrotritartaric acid, with their compounds,
are derived from furfurane (Knorr). R. Fittig thinks that they are derivatives of
hypothetical tetrylone (p. 521) (Berichte, 22, 146).

Isocarbopyrotritartaric Acid, OjHjOj, of unknown constitution, is isomeric
with methronic and carbopyrotritartaric acids. It is formed when diaceto-succinic
ester is distilled [Berichte, 22, 158).

THIOPHENE GROUP.*

Thiophene, C4H4S, an analogue of furfurane, CiH^O (p. 521),
exhibits, in a more marked degree than the latter, a complete anal-
ogy with benzene, CgHs ; its derivatives are perfectly analogous to
those of benzene. It may be viewed as a benzene, in which one
of the three acetylene groups, CH:CH, has been replaced by S,-

* V. Meyer, Die Thiophengruppe, 1888.

THIOPHENE GROUP. 529

the original properties not being essentially altered. By the replace-
ment of the 4-H atoms in thiophene, by other elements or groups,
we obtain innumerable derivatives, in all respects analogous to those
derived from benzene. All thiophene compounds give an intense
blue coloration — the indophenin reaction, Berichte, i6, 1473 —
when mixed with a little isatin and concentrated sulphuric acid.
The methods of forming the thiophenes synthetically from (i, 4)-
or T-'dicarboxyl compounds, have been given on pp. 329, 522). It
may be well to again direct attention to the ready transposition of
the j'-ketonic acids, which yield oxythiophenes when heated with
P2S5, or thiophene hydrocarbons if P2S3 be employed {Berichte, 19,
551; 23, 1495):—

CHj.CO.CH3 CH,=C/ CH=C /

I yields I >S and | >S .

CH^.COjH CH=C. CH=CH

^OH

Lsevulinic Acid. (i, 4)-Oxythiotolene. a-Thiotolene.

(i, 3)-Thioxene, CiH2S(CH3)2 {Berichte, 20, 2017), and (i, 2)-
thioxene {Berichte, 20, 2577) are similarly produced from a-methyl-
Isevulinic acid, CH3.CO.CH2.CH(CH3).C02H, and /S-methyl-lsevu-
linicacid, CH3.CO.CH.CH3.CH2.CO2H {Berichte, 21, 3451). The
isomerisms of thiophene derivatives correspond to those of furfurane
and are similarly named (p. 523). The a-derivatives (those in
which the H-atom is adjacent to the sulphur-atom) were formerly
termed /3-derivatives, and the real /J-derivatives considered as and
designated ^-derivatives. In the following pages the correct desig-
nations, corresponding to the thiophene formula (p. 521), have
been introduced {Berichte, 19, 2890).

The thiophene bodies were discovered by V. Meyer, in 1883.

Thiophene, QH^S, and its homologues, occur in ordinary, im-
pure coal tar. The individual thiophenes are contained in the
corresponding commercial benzene hydrocarbons (about 6%).
They have the same boiling points as the latter. Thiophene is pres-
ent in benzene, methyl thiophene (thiotolene), C4H3S.CH3, in tolu-
ene, CeHs.CHa, dimethyl thiophene (thioxene), C4H2S(CH3)2, in
xylene, C6H4(CH3)2, etc. Benzenes containing thiophene show the
indophenin reaction (see above). The latter is not observed until
the benzenes have been fully purified by shaking them with sul-
phuric acid. The latter withdraws the thiophenes.

Thiophene is synthesized by various reactions : By conducting
ethyl sulphide through tubes heated to redness or passing ethylene
or illuminating gas over heated pyrite, FeSj ; and by heating cro-
tonic acid, butyric acid, etc., with P2S5. It is produced quite abun-

53° ORGANIC CHEMISTRY.

dantly upon heating a mixture of succinic anhydride, or sodium
succinate with ¥Ss (Volhard) : —

CHj.COjNa . CH = CH,

I and PjSj yield | >S.

CHi,.C02Na CH = Cli^

Preparation. — Shake ordinary benzene for some liours with sulphuric acid
(10-4 per cent.), then separate the black acid-layer (containing the thiophene as a
sulpho-acid) from the benzene, and dilute the former immediately with water.
Some benzene sulphonate is usually present with the thiophene sulphonate, but its
quantity diminishes as the quantity of sulphuric acid is decreased. When but 4
per cent, of the latter is present the thiophene-sulphonate is almost pure. To lib-
erate the thiophene from its sulphonate, convert the latter into its lead salt, and
decompose this by distilling it with ammonium chloride [Berickte, 17, 792). Or
the thiophene sulphonic acid is mixed with water and distilled in a current of
steam (JSerichte, 18, 497).

All the thiophene present in crude benzene can be removed from it as dibrom-
thiophene, C^H2Br2S, by the addition of a little bromine [Berichte, 18, 1490).

To obtain thiophene from succinic acid heat a mixture of sodium succinate
(100 gr.) and PjSg (100 gr.) in a retort over the direct flame until the reaction
sets in. The thiophene is expelled from the distillate when the latter is heated
upon a water bath {Berichte, 18, 454).

Thiophene is a colorless liquid, with an odor resembling that of
benzene. It boils at 84°. Its sp. gr. is 1.062 at 23°. It becomes
crystalline when exposed to a mixture of solid carbon dioxide and
ether. Sodium has no effect upon it even when it is heated.
Mixed with a little sulphuric acid and isatin it becomes dark blue
in color. The same occurs when its solution in sulphuric acid is
added to phenanthraquinone in glacial acetic acid (Reaction of
Laubenheimer, Berichte, ig, 673). All the dicarbonyl compounds,
CO. CO, like benzil, alloxan, etc., behave the same as phenanthra-
quinone {Berichte, 16, 2962).

THIOPHENE HOMOLOGUES.

In these compounds the hydrogen of thiophene has been re-
placed by alkyls. They may be obtained by the action of alkyl
iodides and metallic sodium upon iodothiophene (analogous to
Fittig's synthesis of the benzenes) {Berichte, 17, 1559) : —

C^HglS + C2H5I + 2Na = CiH5(C2H5)S + 2NaI.

Only the methylated thiophenes occur already formed in coal tar-
oil. They correspond fully to the homologous benzenes, and with
isatin and phenanthraquinone yield colors similar to those obtained
with thiophene.

THIOPHENE HOMOLOGUES. 53 1

1. Methyl Thiophenes, Thiotolenes, C4H3S.CH3.

a-Thiotolene, C4H3S.CH3, containing the methyl group in the a-position
(p. 523), is produced from iodothiophene by the aid of methyl iodide and sodium,
and from laevulinic acid by the action of PjSj (p. 529). It boils at 126°, and is
converted into a-thiophenic acid by oxidation.

/3-Thiotolene, C4H3S.CH3, is formed when sodium pyrotartrate is heated with
PjS3 {Berichte 18, 454) : —

CH3.CH.C02Na CH3.C = CH

I andPjSa yield | )S. It boils at 113°.

CH^.COjNa CH = CH-^

It becomes /3-thiophenic acid when oxidized.

Both thiotolenes occur in coal tar (in toluene), and may be isolated from it in
the same manner that thiophene is extracted. Formerly their mixture was con-
sidered a distinct thiotolene, as the tribromthiophene and the thiophenic acid, ob-
tained from it appeared to differ from the corresponding a- and /3-thiophene deriv-
atives. Later research has shown it to be a mixture (^Berichte, 18, 3005).

2. Dimethyl Thiophene, Thioxene, 0^1128(0113)2.

(l, 2)-Dimethyl Thiophene is obtained from /5-methyl-laevulinic acid, CH3.
CO.CH(CH3).CH2.C02H, by the action of P2S3 (p. 529). It boils at 136°, and
is oxidized to (i, 2)-thiophene-dicarboxylic acid by potassium permanganate.

(i, 3)-Dimethyl Thiophene is formed when P2S3 acts upon a-methyl-l£evulinic
acid (p. 529). It is an oil, boiling at 137-138°. It gives an emerald green col-
oration with isatin. Alkaline permanganate oxidizes it to (l, 3)-thiophene-dicar-
boxylic acid.

(i, 4)-Diinethyl Thiophene is 7%«oxi?»^, obtained from xylene. It maybe syn-
thesized by acting upon a-iodothiotolene with methyl iodide and sodium. It is also
formed when PjSj'acts upon acetonyl acetone (p. 329). It boils at 135°, yields
a cherry-red color with isatin, and with phenanthraquinone, etc., a violet colora-
tion. Potassium permanganate oxidizes it to (l, 4)-thiophene-dicarboxylic acid.

(2, 3)-Diniethyl Thiophene has' been obtained from symmetrical dimethyl-
succinic acid by the action of P2S3. It boils at 145° {^Berichte, 21, 1836).

a-Ethyl Thiophene, C^HjS.CjHj, from a-iodo- or brom-thiophene by means
of ethyl bromide and sodium, is very similar to ethyl benzene. It boils at 132-
134°. Permanganate oxidizes it first to thienylglyoxylic acid, and then to a-thio-
phenic acid.

/3- Ethyl Thiophene, C4H3S.C2H5, is produced upon heating ethyl succinic acid
with P2S3. It is perfectly similar to the a-compound, but yields /3-thiophenic acid
when oxidized (^Berichte, 19, 3284).

Trimethyl Thiophene, C4H(CH3)3S, has been obtained from dimethyl-lsevu-
linic acid by the action of P2S5 {Berichte, 20, 2085).

a-Normal Propyl Thiophene, C4H3S.C3H,, boils at 158°, and yields a-thio-
phenic acid when oxidized {Berichte, 20, 1740). Isopropyl Thiophene, C4H3S.
CjH,, is prepared by the action of aluminium chloride upon thiophene and iso-
propylbromide. Sodium will not answer in this reaction. It boils at 154°. Un-
like all other homologous thiophenes it yields an intense violet color directly with
phenanthraquinone (Berichte, 19, 673).

Tetramethyl Thiophene, C^SiCHj)^, is obtained from iodo-trimethyl thio-
.phene by the action of methyl iodide and sodium. It boils about 183° {Berichte,
21.1838). .

a-Methyloctyl Thiophene, CiHjSf^^ j| \ (l, 4), from a-methylthiophene,

is identical with that obtained from a-octylthiophene. This is proof of the simi-
larity of the two a-positions (l) and (4) in thiophene (Berichte, 19, 649).

532 ORGANIC CHEMISTRY.

a-Phenylthiophene, €41133.05115, is prepared by heating /3-benzoyl propionic
acid or j8-benzoylisosuccinic acid with PjSs or PjSj : —

CH2.CO.CjH5 CHj.CO.CjHj CH = C^^s^^i

I and I yield | >S .

CH^.COjH CH(COjH)j CH = CH

^-Benzoyl-propionic Acid. (3-Benzoyl-isosuccinic Acid. a-Phenylthiophene.

Tlie product crystallizes from alcohol in small plates, melting at 40-41°
[Berichie, ig, 3140). /PH

Methylphenyi Thiophene, C,H,S^p tI . The (i, 4)-compound results from

the action of PjSj upon acetophenon-acetone, CjHj.CO.CH, CH^.CO.CHg. It
melts at 51° and boils at 270°. (i, 3)-Methylphenyl thiophene, from a-phenyl-
leevulinic acid and PjSj (p. 529), melts at 73° {Berichte, 20, 2558).

HALOGEN DERIVATIVES.

Chlorine and bromine attack thiophene in the cold. The action is even more
energetic than with the benzenes. Iodine, in the presence of mercuric oxide
(p. 91), also attacks it at the ordinary temperature. The three halogens first
enter the a-position. In properties the haloid thiophenes are very similar to the
benzene haloids.

a-Chlorthiophene, C4H3CIS, boils at 130°, and Dichlorthiophene, C^HjCljS,
at 170°. Tetrachlorthiophene, C4CI4S, melts at 36°, and boils from 220-240°.
When thiophene is brominated, even in the cold, the chief product is the dibromide.
A little of the monobromide is formed at the same time.

a-Bromthiophene, C^HjErS, boils at 150°. It yields a-ethylthiophene, when
acted upon by ethyl iodide and sodium, (i, 4)-Dibromthiophene, C^HjBrjS,
boils at 211°. Its formation serves for the complete isolation of all the thiophene
that may be present in a thiophene-benzene {Berichle, 18, I490). Tribromthio-
phene, C^HBrjS, melts at 29°, and boils at 260°. Tetrabromthiophene, CjBr^S,
is the final product in the bromination of thiophene. It crystallizes in brilliant
needles, that melt at 112°, and boil at 326°.

a-Iodo-thiophene, C4H3IS, is obtained from thiophene by the action of iodine
and mercuric oxide, even in the cold. It is a liquid and boils at 182°. Chlorcar-
bonic ester and sodium convert it into a-thiophene carboxylic acid. Diiodothio-
phene, C^HjI^S, melts at 40°.

NITRO-DERIVATIVES.

The action of nitric acid upon thiophene is so very energetic that in order to
moderate the reaction air charged with thiophene vapor is conducted into the
fuming nitric acid. Mono- and dinitrothiophene are then produced [Berichte, 17,
2648).

Nitrothiophene, C4Hj(N02)S, is quite similar to paranitrotoluene. From cold
solutions it separates in bright yellow prisms, melting at 44° and boiling at 225°.
Its odor resembles that of nitrobenzene.

Dinitrothiophene, C4Hj(NOj)2S, resembles dinitrobenzene. It melts at 52°
and boils at 290°. It is volatile with steam. Caustic potash colors its alcoholic
solution dark red. The same coloration of dinitrobenzene, caused in the same
way, is due to admixed dinitrothiophene [Berichte, 17, 2778). When repeatedly
distilled with water dinitrothiophene is converted into a modification, melting at 78°.

THIOPHENE PHENOLS. 533

AMIDO-DERIVATIVES.

Nitrothiophene is reduced with much more difficulty than the nitrobenzenes.
The reduction succeeds when zinc and hydrochloric acid are allowed to act upon
the dilute alcoholic solution [Berichte, 18, 1490).

Amidothiophene, Thiophenin, C^HjS.NHj, analogous to aniline, is a bright
yellow oil. It rapidly resinifies on exposure to the air. Its HCl-salt consists of
deliquescent needles. It does not yield a diazo-derivative when acted upon with
nitrous acid. It combines immediately with salts of diazobenzene, forming stable,
mixed azo-dyestufifs, e.g., CgHj.NiN— CjHjS.NH2.HC]L(.g,fr!V/4/?, 18, 2316).

SULPHO-ACIDS.

Like the benzene sulphonic acids, the thiophene sulpho-deriiratives are produced
by dissolving thiophene in sulphuric acid, generally at the ordinary temperature.
They can also be prepared from the thionyl-ketones (p. 534) (Berichte, 19, 674,
2623) : —

CiH3S.CO.CH3 4- SO^H^ = CiHjS.SOgH + CHj.COjH.

a- Thiophene Sulphonic Acid, C4H3S.SO3H, is formed upon shaking thiophene
with ordinary sulphuric ?iaA [Berichte, ig, 1615). The acid, liberated by hydro-
gen sulphide from its lead salt, consists of very deUquescent crystals. If it be
distilled it yields thiophene. Its derivatives are perfectly analogous to those of
benzene-sulphonic acid.

;8. Thiophene Sulphonic Acid, C4H3S.SO3H, is obtained when sodium amal-
gam acts upon a-dibrom-thiophene sulphonic acid. It is very similar to the
o-acid.

(l, 4)-Thiophene Disulphonic Acid, C4HjS(S03H)2, is produced by the
action of fuming sulphuric acid upon the a-mono- sulphonic acid, while (2, 3)-
Thiophene Disulphonic Acid, C4H2S{S03H)2, is obtained by reducing a-dibrom-
thiophene-disulphonic acid, CiBrjSfSOjH)^, with sodium amalgam [Berichte, 19,

184).

The sulphonic acids of the homologous thiophenes cannot be prepared by
sulphonating the latter, but are derived from their ketone compounds. Thus,
methylthienyl-methyl-ketone yields Methylthiophen-sulphonic Acid, C^H^
(CH3)S.S03H [Berichte, ig, 1620) :—

C4Hj(CH3)S.CO.CH3 + SO4H2 = C4Hj(CH3)S.SOjH + CHj.COjH.

PHENOLS.

a Oxythiophene, C4H3S.OH, is not known. Thienylsulphydrate, C4H3S.
SH, corresponding to it, is prepared by reducing a-thiophene-sulphonic Chloride,
CjHjS.SOjCl, with zinc and hydrochloric acid. It is present in the crude thio-
pheiie product obtained by distiUing succinic acid with PjSj. It is a yellow oil,
with a very unpleasant odor. It boils about 166°. It unites with benzene diazo-
compounds to form azo-dyestufifs. Phenol does not show this reaction [Berichte,
ig, 1617).

a-Oxymethylthiophene, Oxythiotolene, C4H2(CH3)S.OH(i, 4), is synthet-
ically prepared by heating Igevulinic acid with P^Sj. If PjSj be employed the
oxythiotolene will be further reduced to a-thiotolene (p. 531). It is a colorless oil,
with a disagreeable odor. It boils about 200°. It is soluble in alkalies. Carbonic
acid again separates it [Berichte, ig, 555)-

534 ORGANIC CHEMISTRY.

ALDEHYDES AND KETONES.

a-Thiophen-Aldehyde, C4H3S.CHO, results from the distillation of thienyl-
glyoxylic acid, C4H3S.CO.COjH {Berichte, 19, 1885). It is a yellow oil, with an
odor resembling that of benzaldenyde, CjHj.CHO. It boils at 198°. It has all
the properties of an aldehyde. It reacts with fuchsine-sulphurous acid and diazo-
benzenesulphonic acid (p. 189) ; combines with hydroxjlamine to thiophenaldoxime
and with phenylhydrazme to thiophenalhydrazone, C4HjS.CH{N2H.C5H5), melt-
ing at wc/' {Berichte, 19, 637; 1854). Thiophenaldehyde, like benzaldehyde,
condenses with dimethyl aniline, forming a green dye, corresponding to malachite
green.

If oxidized, even in the air, it forms a-thiophenic acid. Aqueous caustic potash
converts it into thiophenic acid and thiophene alcohol : 2C4H3S.CHO -(- KOH =
CjHjS.COjK + C4H3S.CH2.OH.

a-Thiophene Alcohol, C4H3S.CHj.OH, thienyl carbinol,is an aromatic liquid,
boiling at 207°. It is perfectly analogous to benzyl alcohol, C5H5.CHj.OH.

The ketone derivatives of thiophene are obtained in the same manner as those of
the benzene series, viz., by the action of acid chlorides upon thiophene in the pres-
ence of aluminium chloride (reaction of Friedel) [Berichte, 17, 2643) : —

C4H4S -f CjHjOCl = C4H3S.CO.CH3 + HCl.

a-Thienyl-methyl Ketone, C4H3S.CO.CH3, Acetothienone, the analogue of
acetophenone, CgH5.CO.CH2, is obtained from thiophene and acetyl chloride by
means of aluminium chloride. It is an oil, boiling at 2 1 3°. Its odor resembles
that of acetophenone. Being a ketone, it unites with both hydroxylamine and
phenylhydrazine. If it be oxidized with permanganate, it first forms thiophene gly-
oxylic acid, C4H3S.CO.CO2H, and then a-thiophenic acid [Berichte, 19, 2115).

Methyl ihienyl-methyl ketone, C4H2(CH3)S.CO.CH3, acetyl thiotolene, from
a-methyl thiophene and acetyl chloride, boils at 216°.

Acetyl thioxene, C4H(CH3)2S.CO.CH3, from thioxene and acetyl chloride,
boils at 224°. It yields thiophene tricarboxylic acid when oxidized with perman-
ganate.

When these ketones are heated with concentrated sulphuric acid, the acid radical
breaks off, and thiophene sulphonic acids are produced (p. 533). If, however, SO3
or pyrosulphuric acid be allowed to act in the cold upon the ketones, then the pro-
ducts will be ketone-sulphonic acids {Berichte, 19, 2624).

Thienyl Cyanide, C4H3S.CN, Thiophene nitrile, is obtained by distilling po-
tassium thiophen-sulphonate with potassium cyanide or yellow prussiate of potash.
It is perfectly similar to benzonitrile (phenylcyanide), and is an oil, having an odor
very similar to that of oil of bitter almonds. It boils at 190°.

THIOPHENE CARBOXYLIC ACIDS.

Thiophene carboxylic acids are formed by methods which are per-
fectly analogous to those employed in the preparation of the aro-
matic acids: —

(i) By the oxidation of the homologous thiophenes with a solu-
tion of alkaline potassium permanganate {Berichte, 18, 546). The
side chains are thus converted into carboxyl groups. Ethyl-thio-
phene first yields thiophene- glyoxylic acid, C4H3S.CO.CO2H, but

METHYL-THIOPHENIC ACID. 535

this changes to thiophenic acid. The thiophene ketones, under
similar treatment, yield first ketonic acids and then carboxylic acids
(^Berichte 18, 537).

(2) By the action of chlor-carbonic ester and sodium amalgam
upon iodo- or brom- thiophene: —

C^HJS + ClCOj.CjHj + 2Na = C^HgS.CO^.C^H^ -f NaCl + Nal.

The thiophene carboxylic acids are perfectly similar to the ben-
zene carboxylic acids in external properties and reactions. They
split off carbon dioxide and revert to thiophene, C4H3S.CO2H ^
C4H4S -|- CO2, when distilled with lime.

a-Thiophene Carboxylic Acid, QHaS.COjH, is formed when
a-ethyl thiophene is oxidized with potassium permanganate ; .when
chlorcarbonic ester and sodium act upon mono- or di-iodo-thiophene
{Berichte, 18, 2304) ; and upon heating mucic acid with barium
sulphide (p. 522), when carbon dioxide is expelled. The acid is
very similar to benzoic acid ; it crystallizes from hot water in flat
needles, melts at 126.5°, ^"^d boils at 260°. It is very volatile in a
current of steam. Its vapors, like those of benzoic acid, produce
coughing. Its ethyl ester, C4H3S.CO2.CjH5, boils at 218°-

/S-Thiophene Carboxylic Acid, C4H3S.CO2H (2 = 3), is pro-
duced when /J-methyl thiophene is oxidized with potassium perman-
ganate (^Berichte, 18, 3003;. 19, 3284). It crystallizes from water
in thick needles. It volatilizes very readily in a current of steam.
It sublinres in leaflets, and melts at 136°.

If two parts of the a-acid and I part of the /3-acid be crystallized together; homo-
geneous needles separate. These melt constantly at 116-117°, ^°'i cannot be re-
solved into their components again by fractional crystallization (SericAte,ig, 2891).
The same compound, melting at 118°, is produced when crude thiotolene (from a-
and /3-thiotolene, p. 531) is oxidized {Berichte, 18, 548), and when thiophen-nitrile,
C4H3S.CN (from thiophene sulphonic acid, p. 533), is saponified with alcoholic
potash. It was formerly thought to be a peculiar isomeric thiophene carboxylic
acid and bore the name of a-thiophene carboxylic acid {Annalen, 236, 200).

METHYL-THIOPHENIC ACIDS.

'pTT

a-Methyl Thiophenic Acid, C^HaS^^^Q 'jj (i, 4), a-Thiotolenic Acid, is

prepared by the action of chlorcarbonic ester and sodium amalgam upon mono-
and di-iodo-thiotolene {Berichte, 18, 2304; ig, 656), as well as by the oxidation of
synthetic thioxene with a permanganate solution. A little of the dicarboxylic acid
is formed simultaneously {Berichte, 18, 2254). It melts at 137° (142°), and passes
into the corresponding dicarboxylic acid when further oxidized.

^-Methyl Thiophenic Acid, Qfi^%(^^-^, ^-Thiotolenic Acid, results

from the interaction of /3-iodothiophene and chlorcarbonic eiltx [Berichte, 19, 657),
and by the oxidation of acetyl-^-thiotolene, C4H2S{CH3).CO.CH3. It melts at
144°. It does not yield a dicarboxylic acid when further oxidized (Berichte, ig,
680).

S36 ORGANIC CHEMISTRY.

a-Thienyl-acetic Acid, C4H3S.CH2.CO2H, results upon reducing a-thienyl-
glycoUic acid by digesting it with hydriodic acid and phosphorus. It dissolves
with difficulty in water, and melts at 76°.

a-Ethyl Thiophenic Acid, C4H2(C2H-)S.C02H (i, 4), is obtained from
iodoethyl thiophene and chlorcarbonic ester. It melts at 71°-

Keton-Acids and Oxy-Acids.

a-Thienylglyoxylic Acid, C4H3S.CO.CO2H, is obtained by carefully oxidiz-
ing acetyl thiophene, or ethyl thiophene, with permanganate {Berichte, 18, 537 ;
ig, 21 15). It is a crystalline mass, readily soluble in water, and when perfectly
anhydrous it melts at 91.5°. It decomposes into carbon dioxide and thiophen-
aldehyde when heated.

See Berichte, 20, 1746, upon three isomeric methylthienylglyoxylic acids.

Sodium amalgam converts thienylglyoxylic acid into

Thienylglycollic Acid, C4H3S.CH(OH).C02H, corresponding to mandelic
acid, C5H5.CmOH).C02H. It is very soluble in water and melts at 115° {Be-
richte, ig, 3281).

POLYCARBONIC ACIDS.

Thiophene Dicarboxylic Acids, C^^.f^O^)^. Four acids of this class
are possible ; three of these are known.

The (7, 2)-acid, obtained by oxidizing (i, 2)-thioxene with permanganate, de-
composes if it be heated above 260°. Like phthalic acid, it forms a fluorescein
with resorcinol.

The [i,j)-acid, from (i, 3)-thioxene, is volatile with steam, and crystallizes
from hot water in thin needles, melting at 118°. The (7, 4)-acid is prepared as
follows :—

(1) By oxidizing (i, 4)-thioxene, a-methyl- and a- ethyl -thiophenic acid, and
acetyl-ethyl thiophene (p. 534) with permanganate {Berichte, ig, 3275) ; (2) From
athiophene disulphonic acid by means of the dicyanide {Berichte, ig, -igi); and
(3) From dibromthiophene and chlor- carbonic ester. It dissolves with great diffi-
culty in cold water. It is a crystalline powder, that sublimes without melting, at
a temperature above 300°. In most of its properties it resembles terephthalic acid,
CgH4(C02H)2 (l, 4). Sodium amalgam reduces it to

Tetrahydro-thiophene Dicarboxylic Acid, €41158(00211)2. This compound
dissolves readily in cold water, and melts at 162°. It reduces ammoniacal solutions,
especially upon warming. When heated with sulphuric acid it evolves carbon
monoxide and sulphur dioxide. In this respect it resembles the hydrophthalic
acids {Berichte, ig, 3274).

Thiophene Carboxylic Acid, C4HS(C02H)3, is obtained by oxidizing acetyl-
thioxene with potassium permanganate. Its trimethyl ester crystallizes from alco-
hol in leaflets, melting at 118° {Berichte, 18, 2303).

Thienyl Acrylic Acid, C4H3S.CH:CH.C02H, contains an unsaturated side-
group. It is analogous to cinnamic acid. Like the latter it can be prepared from
thiophene aldehyde, by means of sodium acetate and acetic anhydride (see furfur-
acrylic acid). It crystallizes from hot water in needles, melting at 138° {Berichte,
ig, 1856).

CONDENSED THIOPHENE DERIVATIVES.

Dithienyl, C4H3S.C4H3S, corresponding- to dipheuyl, CgHj.CjHj, is produced
when thiophene vapors are conducted through a tube heated to redness. It is quite
similar to diphenyl, crystallizes in bright leaflets, that melt at 83° and boil at 266°.

PENTHIOPHENE DERIVATIVES. 537

Thiophene condenses with the aldehydes of the marsh gas series, forming com-
pounds quite analogous to the diphenyl-methane compounds : —

CH,0 + 2C,H,S = CH^/^^g^S ^ H,0.

Dithienyl Methane, CjHjS.CHj.C^HgS, from thiophene and methylal (p. 301)
by the action of sulphuric acid, is an oil with the odor of oranges. It boils at 267°.
It solidifies when cooled, and melts at 43°-

Dithienyl Trichlor-ethane, (C4H3S)2CH.CCl3,from thiophene and chloral,
HOC.CCI3, forms plate-like crystals, melting at 76°.

Thienyl-phenyl Methane, C^HjS.CHj.CgHj, is obtained by the action of
sulphuric acid upon thiophene and benzyl alcohol, CjHj.CHj.OH. It is an oil,
boiling at 265°. It has a fruity odor.

Dithienyl Ketone, C4H3S.CO.C4H3S, Thienone, is perfectly similar to ben-
zophenone, (CjHj)^^©, and is produced by analogous methods: by the action of
phosgene upon thiophene in' the presence of aluminium chloride {Berichte, 18,
3012) : COClj + 2CiH^S = CO(C4H3S)j + 2HCI; and by the distillation of
calcium a-thiophenate. It crystallizes from alcohol in needles or leaflets, melting
at 88° and boihng at 326°.

Thienyl-phenyl Ketone, C4H3S.CO.CgH5, is obtained from thiophene and
benzoyl chloride by the aid of aluminium chloride: C4H4S -|- CjHj.COCl =
C4H3S.CO.CeH5 -f HCl. It melts at 55°, and boils about 360°. When heated
with lime, it decomposes into thiophene and benzoic acid. ,

Thienyl-diphenyl Methane, C4H3S.CH<' ^^rr^, is produced by the con-
densation of thiophene and benzhydrol, (C5H5)2CH.OH, by means of PjOj. It
crystallizes in white leaflets, that melt at 63° and boil about 335° {Berichte, 19,
1624).

The higher, condensed thiophene derivatives, as Thionaphtene, CjHgS, and
Thiophtene, C5H4S2, will be discussed with the corresponding benzene deriva-
tives.

PENTHIOPHENE DERIVATIVES.

A ring of four carbon atoms linked to or closed by sulphur, exists
(same in the ^--lactone ring) in the thiophene nucleus. Penthio-
phene is an analogous parent nucleus. In it there is a chain of five
carbon atoms closed by sulphur (similar to the 5-lactones) : —

.CH = CH
(y)CH / >S, Penthiophene.

\CH = CH

But very few derivatives are known.

;3-Methyl-penthiophene, C5H5S.CH3, is prepared like thiophene from succinic
acid, by heating sodium a-methyl glutarate with P^Sj [Berichte, 19, 3266) : —

.CH„.CO,H .CH = CH

Ch/ yields Ch/ >S.

\CH.C0,H ^C = CH

I
CH,

45

538 ORGANIC CHEMISTRY.

It is a strongly refracting oil, boiling at 134°. Its specific gravity is 0.994 at
19°. Sodium does not affect it. It resembles thiophene very much in all of its
reactions. It yields a dark green color with isatin and sulphuric acid, and a violet
coloration with phenanthraquinone. Acetyl chloride and aluminium chloride con-
vert it into : —

Methylpenthiophene-methyl Ketone, C5Hi(CH3)S.CO.CH3, acetyl-methyl-
penthiophene. This is a heavy oil, resembling acetophenone, C5H5.CO.CH3, in
odor. It boils about 235°. It forms a ketoxime with hydroxylamine ; this com-
pound melts at 68°.

The penthiophene ring is less stable than that of thiophene. Methyl penthio-
phene is completely oxidized by dilute permanganate even in the cold.

PYRROL GROUP.

In pyrrol, CiHjN, there is a chain of four carbon atoms closed by-
nitrogen. The latter is combined with an atom of hydrogen, thus
forming the imide group (p. 521). The pyrrols, consequently mani-
fest a feeble basic nature ; they gradually dissolve in acids, but do
not form salts v»ith them, as they are resinified. The constitution of
pyrrol and its relations to furfurane and thiophene are deduced from
its analogous syntheses from the ;'- or (i, 4)-dicarbonyl compounds.
These will be more fully discussed later under the individual groups

(PP- 544, 545)- . .

A rather remarkable occurrence is the reversal of these syntheses,
i. e. , the decomposition of the pyrrol ring with elimination of the
imide group. Thisisinducedby the action of hydroxylamine. Di-
oximes are thus produced. Thus, pyrrol yields succindialdoxime (p.
325) (^ifW/%/i?,22, 1968); —

CH = CH CH..CH:N.OH

I >NH -f zHjN.OH = I + NH3.

CH = CH CHj.CH:N.OH

(i, 4)-Dimethyl pyrrol yields the dioxime of acetonyl acetone (p. 328) in a simi-
lar manner.

(i, 3)-Dimethyl pyrrol, (i, 4)-methyl-phenyl pyrrol, and «-ethyl pyrrol react
similarly, while ^-phenyl pyrrol, (i, 4)-diphenyl pyrrol, etc., do not [Berichte, 23,
1792).

The possible isomeric derivatives of pyrrol may be deduced from the following
symbols : —

CH = CH n CH = CH n

I >NH or I >NH.

CH = CH CH = CH

The positions i and 4 are equal in value ; they are called the o-positions. 2 and
3 are also alike, and are termed the /3-positions. Consequently, the mono-deriva-
tives of pyrrol (those in which the CH-groups suffer substitution) occur in two modi-

PYRROL GROUP. 539

fications— the a- and /?. There are four di-derivatives, C4HjRj(NH). Those in
which the two a-positions are replaced, will be termed in the following pages, a or
(i, 4) -derivatives, and the /J/S'-compounds will be called /?- or (2, 3) derivatives, etc.
Tlie compounds formed by the replacement of the hydrogen of the NH-groups,
will be called TV- or ^-derivatives.

Pyrrol, QHiiNH, was first found in coal tar and bone oil. It
received its name from its property of imparting a red color to a
pine shaving, moistened with hydrochloric acid. It is produced
when acetylene and ammonia are conducted throtigh tubes heated
to redness : zCjHj -)- NH3 = C4H1NH -f H^; and by the distilla-
tion of ammonium saccharate or mucate, or upon heating glycerol
to 200°. Its formation upon heating succinimide (p. 412) with
zinc dust containing zinc hydroxide, is very interesting : —

CH^.CO. CH = CH.

I )NH + 2H, = I )NH-f 2H,0.

It also results if pyroglutaminic acid be heated (p. 467). Tetra-
chlorpyrrol, C4CI4NH (^Berichte, 19, 3027), is produced in an
analogous manner from dichlormaleimide (p. 428).

Preparation. — Shake bone oil with dilute sulphuric acid (l : 30) to remove
all basic substances (pyridine bases). The residual oil contains nitriles of the
fatty acids (from propionic to stearic acid), which are saponified upon boiling them
with caustic potash, and in addition benzene hydrocarbons, pyrrol and its homo-
logues {Berichte,\'i, 65). The oil obtained in the distillation of bone-glue (free
from fats) contains large quantities of pyrrols, with a little pyrocoll [Berichte, 14,
1108). To isolate the pyrrol that portion of the purified oil boiling at 115-130°
is treated with metallic potassium, whereupon solid potassium-pyrrol, C^H^NK
(see below), separates. It can also be obtained by boiling the pyrrol with solid
caustic potash {Berichte, ig, 173). The potassium-pyrrol is washed with ether,
decomposed by water, and the oil distilled over in a current of steam. It is then
dried over fused caustic potash and fractionated.

Pyrrol is a colorless liquid with an odor resembling that of chloro-
form. It becomes brown upon exposure and boils at 131°. Its
sp. gr. is 0.9752 at 12.5°. It is but slightly soluble in water, but
dissolves very readily in alcohol and ether. A pine shaving, mois-
tened with hydrochloric acid, is colored a pale red by its vapors.
This increases to an intense carmine red. It yields an indigo blue
coloration with isatin and sulphuric acid, or with phenanthra-
quinone, etc. (p. 521) {Berichte, 17, 142, 1034; 19, 106). Pyrrol
is a very feeble base. It is dissolved very slowly in the cold by
dilute acids, but does not yield salts {Berichte, 21, 1478)- When
heated it passes into a red powder, pyrrol red, Ci^Hi^NjO, which
becomes brown on exposure. Nitric acid resinifies pyrrol and oxi-
dizes it to oxalic acid.

S40 ORGANIC CHEMISTRY.

The conversion of pyrrol into chlor- and brom-pyridine upon heating potas-
sium-pyrrol, or pyrrol and sodium alcoholate, with chloroform or bromoform, etc.
(see pyridine), is rather interesting : —

CH = CH. , CH = CBr. CH

I >NK: + CHBrj =1 I + KBr + HBr.

CH = CH^ CH = CH— N

Brom-pyridine.

Pyrrol is a secondary amine. The hydrogen of its NH-group
can be replaced by potassium (not sodium), acid radicals, and
alky Is.

Potassium dissolves in pyrrol with an energetic evolution of
hydrogen. It forms Potassium-pyrrol, C4H4NK, a crystalline
mass. This compound may also be obtained by boiling pyrrol with
solid caustic potash (Berichte, 19, 1 73). Water regenerates pyrrol
and caustic potash. Sodium will only act upon pyrrol when they
are heated together under pressure.

»- Acetyl Pyrrol, C^H^N.CO.CHj, is produced (together with pyrrol-methyl-
ketone) upon heating pyrrol with acetic anhydride. A simpler procedure consists
in treating potassium-pyrrol with acetyl chloride. It is an oil with peculiar odor.
It boils at 178°. It is decomposed into pyrrol and acetic acid when it is digested
with caustic potash. Hydrochloric acid converts it into a resin.

Cyan Pyrrol, C^H^N.CN, js produced in the action of cyanogen chloride upon
potassium-pyrrol. It rapidly polymerizes to a melamine derivatiM%. In this respect
it resembles cyanamide (p. 288).

»- Pyrrol Carboxylic Ester, C4H4N.CO2.C2H5, Pyrrol Urethane, correspond-
ing to ordinary urethane, is formed when chlor-carbonic ester, acts upon potas-
sium-pyrrol (p. 382). It is an oil boiling at 180°. Boiling alkalies separate it into
its components. It passes into Pyrrol Carbamide, C^H^N.CO.NHj, if it is
heated with aqueous ammonia. This is a crystalline compound that melts at 166°,
and volatilizes without decomposition.

Phosgene, COClj, converts potassium-pyrrol into Carbonyl Pyrrol,
CO;|^-kt'q*tt* (together with the isomeric dipyrryl ketone, p. 545). This com-
pound consists of large crystals, melting at 63°, and distilling at 238°. When
heated in a tube to 250°, it is converted into isomeric dipyrryl ketone,

'^'-'XC*!!' NH C-^^"'^'^''. 18, 1828).

«-Alkyl Derivatives.

The alkylic pyrrols, QH^iNR, containing the alkyl group in
union with the nitrogen atom, correspond to the ordinary amines
(p. 157), and are called N- or «-alkyl pyrrols. The homologous
pyrrols are isomeric with the preceding. They contain the alkyls
attached to carbon (p. 542). The »-alkyl pyrrols are produced by
the action of the alkyl iodides upon potassium-pyrrol, CiH^NK;

SUBSTITUTED PYRROL. 541

also in the distillation of the amine salts of mucic and saccharic

acids, as well as by heating the alkylic succinimides, C4H4 {r^Qy NR

(p. 413), with zinc dust. The «-alkyl pyrrols are quite similar to
pyrrol. They yield intense colorations with isatin and phenanthra-
quinone. They are not so easily resinified by acids as the pyrrols.

»-Methyl Pyrrol, C^H^N.CHg, boils at 113°; its sp. gr. is 0.9203 at 10°.
«-Ethyl Pyrrol, C^H^N.C^Hj, boils at 131°; its sp. gr. is 0.9042 at 10°. A
pine shaving, moistened with hydrochloric acid, is colored an intense red by its
vapors. Ethylamine is liberated when it is boiled with hydrochloric acid. Potas-
sium does not attack it. »-Isoamyl Pyrrol, C^H^N.C^Hj j, boils at 180-184°.
«-Allyl Pyrrol, C^H^N.CjHj, from potassium- pyrrol and allyl iodide, can be
distilled under reduced pressure.

«-Phenyl Pyrrol, C4H^N.C5H5,from aniline mucate and saccharate, cpnsists
of brilliant scales, having a camphor-like odor. They assume a red color on
exposure to the air, and melt at 62°.

SUBSTITUTED PYRROLS.

Tetrachlor-pyrrol, C^^Cl^^NH, is produced by acting upon dichlomaleimide
with phosphorus pentachloride (p. 428) , and when zinc and acetic acid act upon
the perchloride of perchlorpyrocoU (p. 547). It crystallizes from benzine in color-
less leaflets. These volatilize very readily and melt at 110° with decomposition.

Tetra-iodo-pyrrol, CJ^NH, lodol, is formed when iodine
acts upon pyrrol in the presence of some indifferent solvent, but
more readily if substances are present that will absorb the liberated
hydriodic acid (such as iodic acid, p. 91, or caustic alkalies, £e-
richte, ig, 3027).

lodol crystallizes in yellowish-brown prisms. These decompose
about 140°. It is almost insoluble in water ; 100 parts of 90 per cent,
alcohol dissolve 5.8 parts at 15°. If small portions of it be carefully
digested with sulphuric acid they will dissolve, and the solution
acquire an intense green coloration, which subsequently becomes
dirty violet. As tetra-iodo-pyrrol is odorless, but possesses the
same action as iodoform, it has been substituted for the latter as an
antiseptic, under the name oi iodol {Berichte, 20, Ref. 220).

Few pyrrol compounds can be directly nitrated. Nitric acid
attacks them too violently.

Dinitro-pyrrol, C4H2(N02)2NH, is obtained from pyrrol-methyl-ketone,
C,H3(CO.CH3)NH (together with nitro-derivatives of the latter), by the action of
cold fuming nitric acid, and by the nitration of a-pyrrol-carboxylic acid, C4H3
(NH).C02H {Berichte, 19, 1078). It crystallizes from hot water in large yellow .
leaflets, melting at 152°. It behaves like an acid, dissolves in alkaline carbonates
and forms yellow colored salts.

542 ORGANIC CHEMISTRY.

HOMOLOGOUS PYRROLS.

The f-alkyl pyrrol homologues contain the alkyls attached to
carbon. When acted upon by potassium, or if boiled with solid
caustic potash, they form potassium derivatives. This behavior dis-
tinguishes them from the isomeric «-alkyl pyrrols. In the preced-
ing reaction the lower alkyl pyrrols react before the higher pyrrols
{Berichte, ig, 2199). They occur already formed in bone oil.
They are artificially prepared from the corresponding carbonic
acids, which were built up synthetically. The latter lose carbon
dioxide. (p. 545). Some of them have been directly synthesized
from ;--diketones, e. g., acetonyl acetone, CHg.CO.CHj.CHj.CO.
CH3, and acetophenone acetone, CeHs.CO.CHj.CHj.CO.CHs (pp.
328, 522), by heating the latter with alcoholic ammonia: —

CHj.CO.R CH = CR,

I + NH3 = I )NH + 2H,0.

CHj.CO.R CH=^CR^

The c-alkyl pyrrols are also produced together with the «-alkyl pyrrols (p. 540)
by the action of the alkyl iodides upon potassium- pyrrol {^Berichte, 22, 659). The
«-alkyl pyrrols, when heated with alkyl iodides and potassium carbonate to 120-
140°, are converted into M-c-alkyl pyrrols (Berichte, 22, 656, 2515). The H of
CH is then directly replaced. If the heating be prolonged and intensified a simul-
taneous conversion of the <:■ alkyl pyrrols into basic pyridines occurs. The'five-
membered' pyrrol ring is converted into the pyridine ring, consisting of six mem-
bers. The c-alkyl pyrrols sustain a similar conversion into pyridines when they
are digested with concentrated hydrochloric acid {^Berichte, 19, 2199). The
change of the pyrrols, by hydrochloric acid, into derivatives of indol, depends
upon analogous reactions (Berichte, 21, 3429; 22, 1924).

The (T-alkyl indols resemble pyrrol, but are more stable towards
acids. Their aqueous solutions yield a white, caseous precipitate
when treated with a solution of corrosive sublimate.

The possible isomerides of the alkyl pyrrols may be deduced from
the scheme given upon p. 538. The mono-derivatives exist in two
isomeric forms, the a- and /S.

Methyl Pyrrols, C4Hg(NH).CH3, Homopyrrols. The a- and ^-isomerides
both occur in that fraction of Dippel's oil that boils from 140-150°. They cannot
be separated. When carbon dioxide acts upon their potassium compound, two
isomeric methyl-pyrrol-carboxylic acids, C4H2(CH3)(NH).C02H, are produced.
The pure methyl pyrrols result when these acids lose carbon dioxide. a-Methyl
pyrrol boils at 148°, while the /3-variety boils at 143°. They are more readily
changed on exposure to the air than pyrrol. Oxidizing agents convert them into
acetic acid and carbon dioxide. They pass into the corresponding pyrrolcarboxy-
lic acids (a- and /?.) when fused with caustic alkali. If a mixture of the two
methyl pyrrols be heated with acetic anhydride, »-acetyl-methyl pyrrol,C^H3(CH3) N.

r H o ) ^^ {Berichte, ig,

HOMOLOGOUS PYRROLS. 543

ao-Dimethyl Pyrrol, C^H2(CH3)2NH(i, 4), is present in Dippel's oil. It is
obtained from its mono- and di-carboxylic acids, when these lose carbon dioxide
{Berichie, 23, 1475). It may be synthesized by heating acetonyl acetone with
alcoholic ammonia (p. 522). It is a colorless oil, boiling at 165°. It rapidly ac-
quires a red color on exposure to the air. The colorations with isatin and phe-
nanthraquinone are less intense (Berichte, 18, 1566, 2254).

a;8-Dimethyl Pyrrol (1,2) occurs in Dippel's oil. It boils at 165°. Hydro-
chloric acid converts it into tetramethyl indol [Berichte, 22, 1923).

OjS'-Dimethyl Pyrrol, C^H2(CH3)2NH(l, 3), results when its mono- and di-
carboxylic acids (p. 548) lose carbon dioxide. It is an oil, with an odor resembling
that of chloroform. It boils at 160°, and turns brown on exposure to the air
(Annalen, 236, 326).

Ethyl Pyrrol, C4H3(C2H5)NH, is produced by the action of zinc chloride
upon a mixture of pyrrol and aldehyde : C^H^NH + 2C^^O = C4H3(CjH5)NH
■\- C^}A.^^. It boils at 165°. When heated with acetic anhydride, it becomes
«-acetyl-ethyl pyrrol, C4H3(C2H5)N.CO.CH3, and ethylpyrrol methyl ketone,

C^H2(NH)(^^^^jj {Berichte, 19, 2189).

Trimethyl Pyrrol, C4H(CH3)3NH. The two possible isomerides appear to
be contained in that portion of the bone oil that boils at 180-195° {Berichte, 14,
1342).

j8-Isopropyl Pyrrol, C4H3(C3Hj)NH, is formed, analogous to ethyl pyrrol,
by the action of zinc chloride upon a mixture of pyrrol and acetone. It is an oil,
boiling at 175°. It forms ;3-pyrrolcarboxylic acid when fused with caustic alkali
(Berichte, 20, 855).

oa-Methyl Phenyl Pyrrol, C^^iWA)^^ A , is formed by heating aceto-

phenone-acetone, CjH5.CO.CH2.CH2.CO.CH3, with alcoholic ammonia (p. 542).
It crystallizes in brilliant white leaflets, that turn red on exposure, melt at I0I°,
and sublime with partial .decomposition.

/C rr

aa-Diphenyl Pyrrol, C4H2(NH)q r'yC' ("> 4)> '^ produced by the distillation

of pyrrol dibenzoic acid (p. 549), and from aa-diphenyl-pyrrol carboxylic acid (p.
548). It melts at 143.5° {Berichte, 21, 3061).

Tetraphenyl Pyrrol, C4(NH)(C6H5)4,from bidesyl, melts at 211° {Berichte,
22, 553)-

a- Dimethyl pyrrols, in which the imide-hydrogen is also replaced by alkyls,
are formed by the elimination of carbon dioxide from their dicarboxylic acids (ob-
tained firom diacetosuccinic ester and the primary amines, p. 546) {Annalen, 236,
303).

an-Dimethyl-w-methyl Pyrrol, C4H2(CH3)2.N,CH3, Trimethyl Pyrrol, boils
at 169°. ao;-Dimethyl-«-phenyl pyrrol, C4H2(CH3)2N.C5H5, is sol^ji, melts at
52°, and boils at 252° (Corr.). aa-Dimethyl a-naphthyl pyrrol, C4H2(CH3)2N.
CioH,, melte at 71° and boils at 341° (Corr.).

a-Methyl-phenyl pyrrols, the imide-hydrogen of which has also been replaced
by alkyls, are produced from their monocarboxylic acids (obtained from acetophe-
none-aceto-acetic ester and amines) (p. S46) by the loss of carbon dioxide {Berichte,

aa-Methyl-phenyl-K-allyl-pyrrol, C^Hj ( p A IN.CgHj, melts at 52° and
boils at 278°. V^ei^s/

544 ORGANIC CHEMISTRY.

C H jN.CgHj, melts at 84°.

Pyrrol derivatives, whose imide-hydrogen is replaced by divalent radicals, are
produced in an analogous manner by the action of the diamines [e. g., ethylene
diamines, phenylenediamine, benzidine) upon acetonyl acetone, as well as upon
acetophenone-aceto-acetic ester. The compound, C^H2(CH3)2':N.CHj.CHj.N:
C4H2(CH3)j, is thus formed from ethylene diamine and acetonyl acetone [Berickte,
19,3157). Other amide compounds, such as the amido-phenols and the amido-
acids, react similarly with acetonyl acetone and acetophenone-aceto-acetic ester,
forming complex pyrrol imides [Berichte, 19, 558 and 3158).

PYRROL AZO-COMPOUNDS.

The azo- and ifcazo-derivatives of pyrrol are analogous to the benzene azo- dye-
stuffs. They result from the action of the salts of the benzene diazocompounds
upon pyrrol, the pyrrol homologues, and the «-alkyl pyrrols, C^H^N.R, by the
entrance of one and two molecules of the diazo-compounds : —

C,H3(NH).N:N.C,H, and C,H,(NH)/N:N.C,H,_

Pyrrol-azo-benzene, Pyrrol-disazo-benzene.

The mono-azo-compounds are formed in acid solutions, and the disazo-deriva-
tives in neutral or alkaline solution. The former dissolve in concentrated sul-
phuric acid with a yellow color, the latter with a dark blue coloration {Berich/e,
19, 2251).

PYRROL KETONES. PSEUDO-ACETYL PYRROLS.

The pyrrol-methyl ketones, or <:-acetyl pyrrols (together with the
isomeric ^-acetyl pyrrols, p. 540), are produced by heating the
pyrrols with acetic anhydride, and are also prepared by a molecular
rearrangement of the ^-acetyl pyrrols on being heated to 250° {Be-
richte, 18, 1828) : —

CiH4N.CO.CH3, yields C4H3(NH).CO.CH3.

The acetyl group is linked to carbon. They are distinguished
from the ^-acetyl pyrrols by the fact that when they are boiled with
caustic potash they are not decomposed. Being ketones they unite
with hydroxylamine and phenylhydrazine. They condense with
benzaldfihyde, when acted upon with caustic potash, to cinnamyl-
pyrrols. The latter serve to characterize the alkyl pyrrols {Berichte,
22, 1918).

a-Pyrryl-methyl Ketone, CjH3(CO.CH3)NH, pseudo-acetyl pyrrol, resulting
from pyrrol and acetic anhydride [Berichte, 16, 2348), crystallizes from hot water
in long needles, that melt at 90°, and boil about 220°. It is volatile in steam. It

forms an acetoxime, C4H3I C/ ^^-^ jNH, with hydroxylamine, which melts

PYRROL CARBOXYLIC ACIDS. 545

at 146°. Potassium permanganate oxidizes it to the ketonic acid, C4H3(NH).CO.
CO,H (p. 548). Sodium amalgam converts it into pyrryl-methyl carbinol, C^Hj
(NH).CH(OH).CHj, and pyrryl-methyl pinacone {Berichte, ig, 2204).

When bromine acts upon pyrryl-methyl ketone in glacial acetic acid it converts
it into bromine substitution products. If added to cold, fuming nitric acid dinitro-
pyrrol (p. S41), one dinitro and two mono-nitro- products of pyrryl-methyl ketone
are formed {^Berichte, ig, 1078).

Pyrryl-ethyl Ketone, C4H3(CO.C2H5)NH, Propionyl Pyrrol, resulting from
pyrrol and propionic anhydride (together with «-propionyl pyrrol, QHjN.CO.
C2H5), melts at 52°, and distils about 225° (^Berichte, ao, 1761).

Pyrryl Phenyl Ketone, C4H3(CO.CgH5)NH, Benzoyl Pyrrol, is obtained
from pyrrol upon heating it with benzoic aldehyde. It melts at 78°.

The diketone is produced upon heating pyrryl-methyl ketone with acetic anhy-
dride to 250°.

Pyrrylene-dimethyl-diketone, C4H2(CO.CH3)2NH, diacetyl pyrrol, crystal-
lizes from hot water in minute needles, melting at 162°. Potassium permanganate
oxidizes it to carbopyrryl glyoxylic acid (p. 548) (Berichte, 19, 1957).

Dipyrryl Ketone, ^(CjHj.NH),, is produced together with carbonyl pyrrol
(p. S40) by the action of phosgene upon potassium-pyrrol, and by the molecular
rearrangement of carbonyl pyrrol when the latter is heated to 250°. It melts at
100°, but is not decomposed when boiled with caustic potash. Carbonyl pyrrol
also yields Pyrroyl-pyrrol, CjH^N.CO.CjHjNH, melting at 63° {Berichte, 18,
1828).

PYRROL CARBOXYLIC ACIDS.

The acids derived from pyrrol are perfectly analogous to the aro-
matic acids. Their manner of formation is very similar to that by
which the oxybenzoic acids are produced. They result by the oxi-
dation of the homologous pyrrols when fused with caustic potash : —

C4H3(NH).CH3 yields C4H3(NH).C02H,

by the action of carbon dioxide upon the potassium derivatives of
the pyrrols : —

C^H^NK -I- COj = C4H3(NH).C02K,

or by heating the pyrrols with ammonium carbonate, and the action
of carbon tetrachloride and alcoholic potash upon pyrrol {Berichte,

17. 1439) :—

C,H,NH + CCl, -f 4KOH = C,H3(NH).C02H + 4KCI -]- 2H,0.

Dimethyl pyrrol dicarboxylic acid is prepared in a purely synthetic manner by
the action of ammonia upon diaceto-succinic ester (p. 437) : —

CH3,
CH,.CO.CH.CO,R >C = CCOj.R

I .fNH3=NH( I -f2H,0.

CHj.CO.CH.COjR .>C = C.COjR

ch/-

46

^3

546 ORGANIC CHEMISTRY.

The primary amines react the same as ammonia, with formation of dicarboxylic
acids with the alkyl group attached to nitrogen (Knorr, Berichte, 18, 299,

CH,.CO.CH.CO,R ^C = C.CO„R

+ NH,R=RN(' 1' " +2HjO.

CH3.COCH.CO.R \c = C.COjR

CB./

a-Dimethyl-n-alkyl Pyrrol-di-
carboxylic Acid.

Mono-carboxylic acids of methyl-phenyl pyrrol are also formed from aceto-
phenone- (phenacyl-) aceto-acetic ester, by the action of ammonia and primary
amines (PmI, Berichte, 18, 2591) : —

CeHj.CO.CHj ° ^\c = CH

I + NH^R = RN< I + 2H2O.

CH3.CO.CH.CO.R )C C.CO.R

CH/

Acetophenone-aceto- a-MethylphenyI-«-alkyl Pyrrol-

acetic Ester. carboxylic Acid.

The action of amide-acids (like glycocoU) upon acetonyl-acetone (p. 328) and
acetophenone-aceto-acetic esters produces pyrrol acids, in which the acid residues
are combined with nitrogen (Paal, Berichte, 19, 559, 3157), e.g.,

/CH3
CH=C/
I ^N.CjH..C02H, Dimethyl-pyrrol-benzoic Acid.

Analogous compounds are also obtained from diaceto-succinic ester (Annalen,
236, 314; Berichte, 22, 3086).

When the mono- and dicarboxylic acids are heated they part with one and two
molecules of carbon dioxide, forming at the same time the corresponding f-alkyl
pyrrols. When the primary esters of the dicarboxylic acids split off carbon dioxide
they pass into the esters of the mono-carboxylic acids.

a-Pyrrol Carboxylic Acid, C4H3(NH).C02H, Carbopyr-
rolic Acid, was first obtained from its amide, which is produced
together with pyrrol upon distilling ammonium mucate. It is
formed (together with /?-pyrrol carboxylic acid) when carbon di-'
oxide acts upon potassium-pyrrol heated to 200°, and from pyrrol
by heating it with CCI4 and alcoholic potash, as well as by oxidizing
methyl-pyrrol by fusing it with caustic potash. The best method
for its preparation consists in heating pyrrol and aqueous ammonium
carbonate to 120-130° {Berichte, 17, 1150). It crystallizes from
water in colorless leaflets or prisms. When these are dry they
become green in color. They melt at 192° in a closed tube,
decomposing at the same time into carbon dioxide and pyrrol.

PYRROL CARBOXYLIC ACID. 547

Lead acetate does not precipitate its aqueous solution. When
digested with dilute acids it breaks up into carbon dioxide and
pyrrol red.

The esters of the acid are obtained by the action of the alkyl iodides upon its
silver salt. The methyl ester, C^H8(NH).C02.CH3, melts at 73°; the ethyl
ester at 39°. The amide, CjH3(NH).CO.NH2, is formed together with, pyrrol
by the distillation of ammonium pyromucate. It consists of shining leaflets, melt-
ing at 175.5°. It is decomposed into ammonia and carbopyrrolic acid when boiled
with baryta water.

Pyrocoll, CioHeN202 = C^H3 :N— C0\ , the amide anhydride of carbo-

\C0 . N : C4H3
pyrrolic acid, is produced in the distillation of gelatine (p. 539) and is artificially
prepared by healing carbopyrrolic acid with acetic anhydride. It crystallizes in
yellow leaflets, melting about 268°. It yields a-carbopyrrolic acid when it is
boiled with potash. Its formula is established by a molecular weight determins^-
tion by Raoult's method [Berichte, 22, 2501). Bromine converts it into mono-,
di- and tetrabrompyrocoll. These yield brominated pyrrol carboxylic acids when
boiled with alkalies. When it is heated with PCJj, perchlorpyrocoll, Cj^CljNjOj,
and the octochloride, Cj5Clj(Clg)N20j, are produced. Zinc and acetic acid con-
vert the latter into perchlorpyrrol, C^Cl^NH, and on boiling with dilute acetic acid
we obtain the imide of dichlormaleic acid (p. 428).

When pyrocoll is dissolved in nitric acid dinitropyrocoU results ; sodium hydrox-
ide converts this into nitrocarbopyrrolic acid. The latter crystallizes from water in
needles, melting at 146°. The nitration of a-carbopyrrolic acid produces dinitro-
pyrrol {Berichte, 19, 1079) > "^^ methyl ester cannot be directly nitrated [Berichte,
22, 2503).

yJ-Pyrrol Carboxylic Acid, C4H3(NH).C02H (2-3), is pro-
duced on fusing ;3-methyl pyrrol with KOH, and by the action of
CO2 upon potassium-pyrrol at 200°. From an aqueous solution of
the two acids, lead acetate only precipitates the /3-acid. It crystal-
lizes in needles, melting at 161-162° with decomposition into car-
bon dioxide and pyrrol. The same decomposition occurs when its
aqueous solution is evaporated.

Metjiyl Pyrrol Carboxylic Acids, C4H2(CH3)(NH).C02H. Two of the six
isomerides are known. They are produced when carbon dioxide acts upon the
potassium derivative of the crude methyl pyrrol (a and ^). The lead salt of the /3-
acid is very insoluble. The a-acid crystallizes from water in small leaflets. It melts
at 169°; the ^-acid melts at 142°- Both acids, when heated beyond their melting
points, decompose into carbon dioxide and the corresponding methyl pyrrols. This
occurs with the /3-acid on evaporating its aqueous solution.

(I, 4)-Dimethyl Pyrrol -j3-Carboxylic Acid, C^H (CH3)2(NH).C02H. Its
methyl ester is obtained by distilling the monoethyl ester of a-dimeliiylpyrrol di-
carboxylic acid, when it loses carbon dioxide. It melts at Il8°- The free acid
consists of needles, melting at 210-213°, and then decomposes into carbon dioxide
and irffi-dimethyl pyrrol. This happens also when it is treated with concentrated
acids.

Two isomeric (l, 3)-dimethyl pyrrol- carboxylic acids, C4H(CH3)j(NH).COjH,
from (i, 3)-dimethyl-pyrrol-dicarboxylic acid (p. 549) and tetramethylpyrocoU,
melt at 183° and 137° respectively {Berichte, 22, 40).

548 ORGANIC CHEMISTRY.

(1, 4)-Methyl-phenyl-pyrrol-/3-carboxylic Acid, C^H ((^^ j (NH).COjH.

Its ethyl ester is produced by the action of ammonia upon acetophenone-aceto-
acetic ester (p. 546). The free acid crystallizes from glacial acetic acid in yellow
needles, decomposes partially at 175°, and melts about 190°.

Its derivatives, containing alkyl or phenyl groups attached to th^ N-atom, are
similarly produced by the action of primary amines upon acetophenone-acetoacetic
ester (p. 546). *'

(i, 4)-Diphenylpyrrol-^-carboxylic Acid, C4H(C6H5)2(NH).C02H, from
acetophenone-benzoyl acetic ester and ammonia (p. 495), melts at 261° {Berickte,
21, 3060).

KETONIC ACIDS.

a-PyrroylCarboxylic Acid, C^H5(NH).CO.C02H, Pyrryl Glyoxylic Acid,
is produced by the oxidation of a-pyrryl methyl ketone (p. 544) with alkaline po-
tassium permanganate {Berichie, 17, 2949). It crystallizes from water in 5'ellow
needles, welting with decomposition at 74-76°. They become anhydrous when
placed over sulphuric acid. The anhydrous acid, from benzene, consists of yellow
needles, decomposing about 114°. Ferric chloride imparts an intense red color to
the aqueous solution. When fused with caustic potash, it becomes a-pyrrol-car-
boxylic a.cM {Berichte, 19, 1957).

Pyrryl-methyl-ketone Carboxylic Acid, C4H2(NH)/^q^s, Aceto-

pyrrol carboxylitf acid. Its methyl ester is produced pn heating a-pyrrol carboxylic
methyl ester with acetic anhydride to 250°. It melts at 113°. The free acid is
oxidized to carbopyrryl-glyoxylic acid by potassium permanganate [Berichie, ig,
1961).

Carbopyrryl Glyoxylic Acid, C^H^CNHX^^q^^H^ j^ obtained by oxid-
izing pyrrylene dimethyl diketone (p. 545) with potassium permanganate. It is
very unstable. Its dimethyl ester melts at 145°. If oxidized by fusion with
caustic potash, it yields a pyrrol dicarboxylic acid [Berichte, 19, 1959).

DICARBOXYLIC ACIDS.

(z-Pyrrol Dicarboxylic Acid, C^H2(NH) \ ro H^'' 'f^)' ''^^"^'^ "P°" oxidiz-
ing carbopyrryl glyoxylic acid by fusion with caustic potash. It separates from
alcohol in warty crystals. It turns black when heated to 200°, and breaks up into
carbon dioxide and pyrrol. Its silver salt, CjHjNO^Agj, is a caseous precipitate.
Its dimethyl ester, Q,^YL^0^[C11^) ^,ixoTa<C!it. silver salt and ethyl iodide, melts
at 132°. The diethyl ester melts at 82° [Berichte, 19, i960).

(i, 4)-Dimethyl pyrrol-(2, 3)-dicarboxylic Acid, C4(CH3)2(NH) ^^Q^jj.

Its ethyl ester is derived from diaceto-succinic ester and ammonia. It crystallizes
in minute needles, and melts at 99°. If the diethyl ester be saponified with alco-
holic potash the ester acid, melting at 227°, and the free dicarboxylic acid result.
The mineral acids precipitate the latter from its salt solutions in minute needles.
It crystallizes from alcohol in long needles. It melts at 251°, and decomposes
readily into two molecules of carbon dioxide and (i,4)-dimethyl pyrrol. It sus-

PYRROL HYDRIDES. 549

tains the same decomposition when it is boiled with water, or is acted up with
concentrated acids {Berichte, 18, 1558).

For those derivatives of dimethyl pyrrol-dicarboxylic acid, in which the alky Is
and acid residues are attached to the nitrogen atom, consult Annalen, 236, 303.
Hydroxylamine and phenylhydrazine convert diaceto-succinic ester (Annalen,
236, 294) into —

C^(CH3),(N.0H)(C0,R), and C^{CH3),(N.NH.CeH,)(CO,R),.

Unsymmetrical (i, 3)-Dimethylpyrrol Dicarboxylic Acid, €^(0113)2

(NH) f ff )^tf I's diethyl ester may be prepared by reducing a mixture of

acetoacetic ester and nitroso-acetic ester with zinc dust in an acetic acid solution
(^Annalen, 236, 217). It melts at 135°, and also forms a potassium salt, CjjHjg
KNO^. If the diethyl ester be saponified two isomeric ester acids (melting at
202° and 197°) and the free dicarboxylic acid result. The latter dissolves quite
readily in water, and melts at 197°, decomposing into carbon dioxide and a/?'-
dimelhylpyrrol (p. S43)- ■'t forms an imide anhydride with acetic anhydride
(Berichte, 21, 2875).

Pyrrol Dibenzoic Acid, C4Hj(NH)(^^«^*'^q2H^ results from the action
of ammonia upon ethylene dibenzoyl-carboxylic acid : —

CHa.CO.C.H-.COaH CH = C<;

I + NH3 = T )NH + 2H2O.

CH,.CO.C6H..C02H CH = C<

It breaks down into two molecules of carbon dioxide and aa-diphenyl pyrrol
when distilled with lime (p. 543) {^Berichte, 20, 1487).

Pyrrylen-phthalide, CgH^<f ^[?^^^^^il^O, a derivative of phthalide (see

this) is produced, when phthalic anhydride and pyrrol are heated together (Be-
richte, 19, 2201).

PYRROL HYDRIDES.

Dihydro-Pyrrol or Pyrroline, C4H6NH, and Tetrahydropyrrol or
Pyrrolidine, CiHsNH: —

CH,— CH„. CHj— CHj.

I )NH and | >NH,

CH = CH ^ CHj— CH^/

Pyrroline. Pyrrolidine.

are formed when hydrogen is added to pyrrol. These are two
parent substances from which a series of derivatives can be ob-
tained by the replacement of their hydrogen atoms. Pyrrolidine
is perfectly analogous to piperidine.

The following hypothetical parent-nuclei are keto-derivatives
of pyrroline and pyrrolidine : —

550 ORGANIC CHEMISTRY.

CO— CH, . . CH,— CO .

I >NH and I >NH.

CH = CH^ CH,— CH/

j3-Pyrrolon. a-Pyrrolidon,

Pyrroline, C^H^NH, is fonned when pyrrol is digested with zinc dust and
acetic acid. It is a liquid that dissolves readily in water, and boils at 91°- It has
an alkaline reaction, smells like ammonia and unites with acids to form salts. It
is a secondary base. Nitrous acid converts it into niirosamine, C^^l^G),
melting at 38°.

Pyrrol and methyl iodide uoite to dimethyl- ammonium iodide, C4HgN(CH3)2l.
Silver oxide converts this into the ammonium hydroxide, C4HjN(CH3)2.0H.

»-Methyl Pyrroline, C4H5N.CH3, is formed by the action of zinc dust and
acetic acid upon »-methyl pyrrol. It is very similar to pyrroline and boils at 80°.
It unites with methyl iodide to form a dimethyl iodide.

Consult Berichte, 22, 2514 upon benzoyl pyrroline, C4H5N.CO.CsH5, and
benzyl pyrroline.

The supposed derivatives of /3-pyrrolon have been proved to be cyanethyl com-
pounds (Berichte, 22, Ref. 325).

PYRROLIDINE COMPOUNDS.

Pyrrolidine, C4HgNH, Tetramethylene-imine, was first obtained by heat-
ing pyrroline with hydriodic acid and phosphorus to 250"' [Berichte, 18, 2079).
It has been synthetically prepared by distilling the hydrochloride of tetramethylene-
diamine, and by the action of sodium upon an alcoholic solution of succinimide
{Berichte, 20, 2215) : —

CHj.CHj.NHj CH^.CO. CH^.CH^.

I and I )NH yield | ^NH.

CH^.CH^.NHj CHj.CO^ CH^.CH/

Tetramethylene-diamine. Succinimide. Pyrrolidine.

Pyrrolidine is an alkaline liquid with an odor resembling that of piperidine. It
boils at 87°; its sp. gr. at 0° is 0.879. Its nitrosamine, C4H3N(NO), is a yel-
low oil boiling at 214° {Berichte, 21, 290). It combines with methyl iodide to
form Hl-methyl-pyrrolidine, C4HgN.CH3. This can also be prepared by
reducing «-methyl pyrroline with hydriodic acid. Methyl pyrrolidine unites with
methyl iodide to dimethyl ammonium iodide, C4H8N(CH3)2l, which in its entire
behavior resembles piperidine dimethyl iodide, C5Hj(|N(CH3)2l. When fused
with potassium hydroxide it forms dimethyl pyrrolidine, C4H,N(CH3)2; this yields
the ammonium iodide, C4H,N(CH3)3l, with methyl iodide. If this be fused with
caustic potash it becomes trimethylamine, N(CH3)3, and the hydrocarbon C^Hj
(Pyrrolylen) {Berichte, 18, 20S1).

a-Methyl Pyrrolidine, C4H,(CH3)NH, has. been prepared by reducing
a-methyl pyrrolidon (see below) with metallic sodium and alcohol. It is a strongly
alkaline liquid, with a stupefying odor. It boils at 97° {Berichte, 22, 1866).

/3-MethyI Pyrrolidine, C4H,(CH5)NH, results from heating /3-methyl tetra-
methylene-diamine (p. 313) hydrochloride. It is a fuming, alkaline liquid, with
an odor resembling that of piperidine. It boils at 104° and yields a nitrosamine,
boiling at 224° {Berichte, 20, 1657).

offi-Dimethyl Pyrrolidine, C4Hg(CH3)jNH, is derived from diamido-hexane
(p. 314), and boils at 107° {Berichte, 22, 1859; 23, IS44).

Trimethyl Pyrrolidine, C4H5(CH3)3NH, is obtained firom amido-trimethyl-
butylactinic acid (from diacetonamine (p. 208, with CNH, etc). See Annalen,
232, 206.

PYRAZOLE COMPOUNDS. 55 1

The following is a keto-derivate of pyrrolidine, C^HgNH :—
a-Pyrrolidon, C4H50(NH1 (p. 550), is produced when y-amidobutyric acid is
""j^^ '° ^°°° (PP- 369. 372)- It distils at 245°. It is a colorless oil, which
solidifies upon cooling, and melts at 25-28° (BerichU, 22, 3338).

a-Methyl Pyrrolidon, C4H5(CH3)0(NH), is simUarly produced upon heating
r-amidovaleric acid to 250° (p. 372) {Berichte, 22, i860) :—

^„ /CH(CH3).NH, CH(CH3).NH

It forms deliquescent needles, melting at 37°. Nitrous acid converts it into a
nitrosamine. Boiling alkalies regenerate y-amidovaleric acid.

For additional derivatives of pyrrolidon see Berichte, 22, 2364; 23, 708, 888.

AZOLE COMPOUNDS.

The azoles (diazoles, triazoles, etc.) are those compounds in
which there is present a " five-membered " ring, containing two,
three, etc., nitrogen atoms. These nuclei can also be derived from
pyrrol, by simply replacing the CH-groups by nitrogen. Diazole
is known in two isomeric forms — the a- or (i, 2)-diazole, and the
^- or i}> l)-diazole. The first is also called Pyrazok, while the
latter is more familiar under the name of Glyoxaline or Imid-
Azole * .• —

CH = CH CH = CH, CH = CH. N = CH,

I >NH I )nH I \nH I \nH.

CH = CII/ CH = n/ N = Ch/ CH = n/

Pyrrol. a-Diazole, Pyrazok. p-Diazole, Glyoxaline. Triazole.

I. PYRAZOLE COMPOUNDS.

Free Pyrazole, CjH^N^, is prepared by saponifying the addition product of
diazo-acetic ester with acetylene dicarboxylic ester, C3HN2(COj.CH,)3 (p. 375),
when the three carboxyl groups are split off (Berichte, 22, 2165). It can also be
obtained from epichlorhydrin by heating it with hydrazine hydrate, N^H^.H^O,
and zinc chloride [Berichte, 23, 1 105). It crystallizes in colorless needles, melt-
ing at 70° and boiling at 185°. It is feebly basic, reacts neutral, and yields salts
that are not very stable.

Only those pyrazole derivatives, containing benzene residues, are known., Anti-
pyrine belongs to this class. They will be considered after the aromatic com-
pounds.

The addition of hydrogen to pyrazole produces the basic compounds Pyrazoline,
CjHgNj, and Pyranolidine, CjHjNj : —

CHj — CHgv CH, — CHjv

I )NH and | ^NH.

CH = n/ CHj — NH/

* Consult Widmann, /n pr. Ch., 38, 185; Berichte, 21, Ref. 888; Knorr,
Berichte, 22, 2083; Hantzsch, Annalen, 24Q, 4; Berichte, 20, 3 1 18.

552 ORGANIC CHEMISTRY.

2. GLYOXALINE COMPOUNDS.

Glyoxaline, CjH^Nj, the parent substance of the glyoxalines (/3-diazoles or
imidazoles) probably possesses the formula : —

CH— N . CH = CH,

II )CH or I )NH.

CH— NH/ N = CH/

This would ally it both to the amidines, and the anhydrobases and lophines of
the benzene series (Japp, Berichte, l6, 285, 748).

The glyoxalines, like the amidines, do not yield acidyl derivatives with the acid
chlorides, or nitrosamines with nitrous acid. It is for these reasons that the sym-
metrical formula (without the NH-group) is adopted (Radziszewsky, Berichte, 15,
2709) (see below).

Glyoxaline is produced by the action of ammonia upon glyoxal [Berichte, 15,
645). It is easily soluble in water, alcohol and ether. It crystallizes in brilliant
prisms, melting at 89°, and boiling at 255°. It reacts strongly alkaline, and forms
salts with I equivalent of the acids. Alkyl iodides and caustic potash caus^ sub-
stitution of alkyl for the imide hydrogen, forming n-alkyl glyoxalines (Anflakn,
214, 319).

These are liquids with a very peculiar odor. They boil without decomposition,
and combine with the alkyl iodides to form ammonium iodides. They can be
prepared synthetically by acting upon the dialkyl oxamides with phosphorus
pentachloride, and then reducing the amide chlorides and chlorinated bases which
form at first. Hence they have been designated fljro/j'wfj^oxalmethylin, oxalethy-
lin) (Wallach, Annalen, 214, 257) : —

CH-N
yields II ^CH

CO.NH.CH, CH— N<

Dimethyl Oxamide. a-Methyl-glyoxaline.

-CH3

In this manner oxal-ethylin, CgHjpNj, is obtained from diethyl-oxamide. It is
identical with ^-ethyl-c-methyl-glyoxaline.

«-Methyl-glyoxaline [n-Methyl-imid-azole] has also been made from »-methyl-
imidazolyl mercaptau (from amido-acetal and methyl mustard oil). This is
expressed by the accepted unsymmetrical formula of glyoxaline (imid-azole)
[Berichte, 22, 1361).

K- Methyl Glyoxaline, C3H3N2.CH3, obtained by the three methods, is a
strongly alkaline liquid, boiling at 195-199°. It solidifies in the cold and melts
at — 5*. «-Propyl Glyoxaline, C3H3N2.C3H,, boils about 221°.

c-K\ky\ glyoxalines, homologues of glyoxaline, having the alkyl group attached
to carbon, are synthetically produced by the action of ammonia upon a mixture of
glyoxal and aldehyde (therefore called glyoxalethylins) [Berichte, 17, 2402) : —

CHO CH = N.

I + 2NH3 -f CHO.CH3 = II )C.CH3 + 3H2O.

CHO CH— NH'^

The reaction occurs more readily by using glyoxal and aldehyde ammonia
[Berichte, 16, 487). The orthodiketones behave in the same manner with

TRIAZOLE COMPOUNDS. 553

glyoxal. Thus, diacetyl and aldehyde yield ^-trimethyl glyoxaline {Berichte, 21,
141S) :—

CHs.CO CH..C— N .

1 + 2NH, + CHO.CH3 == II ^C.CH3 + 3H,0.

CH3.CO CHg.C— NH^

Benzaldehyde and diacetyl also yield dimethyl-phenyl-glyoxaline [Berichte, 23,
Ref. 248), while triphenyl-glyoxaline (lophine, see this) is produced from benzil
(dibenzoyl) and benzaldehyde.

The c-alkyl glyoxalines or gfaoxalkylins are crystalline solids. They resemble
the alkaloids very closely in all theitjreactions. They are mon-acid imide bases.
The imide hydrogen of the latter is replaced by alkyls.

(T-Methyl Glyoxaline, C3H2(CH3)N2H, glyoxalethylin, consists of brilliant
needles, melting at 137°, and boiling at 267°. It is also obtained by a molecular
rearrangement of «-methyl glyoxaline when the latter is distilled with lime
(therefore it is called Paraoxalmethylin), and from ^-methyl-«-ethyl glyoxaline,
C3H2(CH3).N2.CjH5, when this*Ioses ethylene {Berichte, 14, 424).

f-Trimethyl Glyoxaline, C3(CH3)3N2H,from diacetyl, melts at 183° and boils
at 271°. CHj.NH.

Derivatives of Tetrahydroglyoxaline, C3HJN2 = \ yCHj, have

CHj.NH/

been prepared by the action of aldehydes upon ethylene-aniline, C„H,C mw r°M^

\iMrt,(^ijri5

{Berichte, 20, 732). Hydantoin may be considered a diketo-derivative of tetra-
hydroglyoxaline (p. 391).

3. TRIAZOLE COMPOUNDS.

The triazole nucleus, of five membefs, three of which are nitrogen atoms, exists
in two isomeric forms : —

N = CH. CH = N.

I ^NH and | )NH.

CH = N'^ CH = N^

Triazole. Osotriazone,

The Triazole derivatives appear to be those compounds, which result from
the union of dicyanphenylhydrazine, CjH5.N2H3.C2N2, with acid anhydrides, or
with benzaldehyde (Bladin, Berichte, ig, 2598; 22, 796) ; ditriazole derivatives
(Berichte, 22, 3 1 14) are also formed from the so-called cyanphenylhydrazine,
(CeH5.N2H,)2C2N2.

The Osotriazone derivatives are obtained by boiling the osazones — the dihydra-
zones of the ortho-diketones (p. 326) — with acids (an amide group is elimi-
nated) : —

CH3.C = N.NH.C^Hj CH3.C = N.

I =1 >N.CjH5 + NH2.CJH5,

CH3.C = N.NH.C3H5 CH3.C = N^

or by the transposition of the osotetrazones which first appear {Berichte, 21, 2757).
Triphenylosotriazone, C3N3(CeH5)3 {Berichte, 21, 2806) is similarly obtained firom
benzil dihydrazone.

Urazole is a diketo-derivative of tetrahydrotriazole. Its compounds have been
obtained by the action of phenylhydrazine upon urea and derivatives of the latter
{Berichte, 21, 1219; 20, 3372).

554 ORGANIC CHEMISTRY.

4. THIAZOLE COMPOUNDS.

The thiazole nucleus contains five members; one of them is an N-atom and
another an S-atom : —

aHC— N^

II '^CH II.
P HC— S /

It can be regarded as a diazole, in which the imide group has been replaced by
sulphur, or as thiophene in which one CH-group has been -substituted by nitrogen.
Its entire character is that of pyridine, in which S has replaced two CH-groups,
without affecting any of the essential properties of the parent substance (just as
thiophene is an analogue of benzene) (Hantzsch, Annalen, 249,. I ; 250, 257 ;
Berichte, 20, 3118; 22, Ref. 17 and 256).

Free Thiazole, QHjNS, is produced by exchanging hydrogen for the araido
group in amidothiazole. This is similar to the formation of benzene from amido-
benzene. It is a colorless liquid, boiling at 117°. It resembles pyridine very
closely.

The mono- and dialkylic thiazoles are produced : —

(i) By the condensation of chloracetones with thioacetamides (p. 260): —

CH..C1 HSv CH— S,

I + >C.CH3 = II \C.CH3 + H,0 + HCl.

CH3.CO HN<^ CH3.C N^

Chloracetone. Iso-thio- afi-Dimethyl-thiazole,

acetamide.

Thioacetamide reacts, in a like manner, with chloracetic ester and chlor (brom)-
aceto-acetic ester ; the products formed first are alkyl thiazole-carboxylic acids,
from which the carboxyl groups can be eliminated {^Berichte, 23, 2341).

(2) By reduction of the oxythiazoles (p. 555) when heating them with zinc dust.

(3) By the transposition of amido-alkylthiazoles, in the same manner as thiazole
is obtained from amidothiazole.

The alkylic thiazoles are very similar to their corresponding pyridine bases, and
boil usually 2 — 3° higher than the latter. The carboxylic acids of the alkyl thio-
phenes unite with acids to form salts that are not very stable {^Annalen, 259, 228,
253, 266).

/i-Methyl Thiazole, C3H2(CH3)NS, from thiacetamide and chloracetate, boils
at 128°. a-Methyl Thiazole, from amido-methyl thiazole, and from oxy-methyl
thiazole, boils at 132°.

a|U-Dimethyl Thiazole, C3H(CH3)jNS, from chloracetone and thioacetamide,
boils at 145°. It is very similar to lutidine. Trimethyl-thiazole, C3(CH3)3NS,
is obtained from a-chlormethyl aceto-acetic ester (Berichte, 23, 2341).

Amidothiazoles result from the condensation of chloraldehyde or chloracetones
with thiourea (p. 394) : —

CHjCl HS . CH— S .

I + ^C.NH, = II );C.NH, + HjO + HCl.

CHO HN<^ CH— N<^

Chlor- Isothiourea. ^-Amido-thiazole.

aldehyde.

rt-Methyl-/i-amidothiazole and a-phenyl-//- amidothiazole are produced, in a sirai"
lar manner, from chloracetone and bromacetophenone, CgHg.CO.CHjBr.

OXAZOLE COMPOUNDS. 555

CR— S,
Alkyl Amido-thiazoles, II ^.C.NHR, are obtained by the action of

cr_n/

chloracetones upon mono-alkyl-thioureas, while the diallcyl thioureas yield the

CR— S\„^
dialkylimido-thiazolines, || >C:NR.

CR— NR^

The amido-thiazoles are very similar to the aromatic amines.

They yield diazo compounds, as well as derivatives of the latter.

They become thiazoles by replacing the amido-group by hydrogen.

/i-Amido-thiazole, C3H2(NH2)NS, from chloraldehyde (or dichlor-ester) and
thiourea, crystallizes in yellow plates, that melt at 90°. It has an alkaline reaction
and forms salts.

a-Methyl-/i-amido-thiazole, C3H(CH3)(NH2)NS, from chloracetone, melts
at 42°.

a Methyl-/i-methyl-amidothiazole, C3H(CH3)NS.NH.CH3, from chlorace-
tone and methyl thiourea, is an alkaline oil. It boils at 42° (Bfrichte,7.z, Ref. 21).

Oxythiazoles are prepared from the sulphocyan-acetones. The carbamine thio-
acetones formed at first are transposed on boiling with hydrochloric acid : —

CH3.CO.NHj, CH3.C N.

I >C0 yields || ^C.OH + H.O.

CHj— S^ CH 3/

Acetone-thiocarbamine. a-Methyl-jit-oxythiazole.

The oxythiazoles are slightly acid, unstable compounds.

They speedily revert to the carbamin-thio-ketones. They are reduced to thia-
zoles upon distillation with zinc dust {Berichte, 22, Ref. l8).

Imide-derivatives, compounds of dihydroihiazole, or thiazoline, C3H5NS, are
known {Berichte, 22, 1 144).

Ethylene-isothiourea, C3H5NS (NH), or C3H^NS(NH2), maybe viewed as a de-
rivative of thiazoline, C^^^,ox tkiazolidine, QHjNS [Berichte, 23, 2824).

5. OXAZOLE COMPOUNDS.

The parent nucleus of oxazole is perfectly analogous to thiazole. It contains an
oxygen atom instead of the sulphur atom. It bears the same relation to thiazole
that furfurane, C^H^O, bears to thiophene : —

CH— O.

II /;CH, Oxazole.

CH— N^

The alkylic oxazoles, like the alkylic thiazoles, are produced by the condensa-
tion of chloracetone with acid-amides [Berichte, 21, 2192): —

CHjCl HN,^ CH— N^,^

I + ^CCeHj = II );C.C,H, -f H,0 -f HCl.

CH3.CO HO/ CH3.C O^

Chloracetone. Isobenzamide. ^-Methyl-ju-phenyl Oxazole.

The resulting methyl-phenyl oxazole, Cj ^HgNO, is a colorless oil, boiling at
240°. It has a feeble, alkaline reaction and dissolves in acids.

Ethylene-pseudo-ureas (p. 391, Berichte, 22, 1151), the products of the transpo-
sition of brom-ethyl urea, are derivatives of dihydro-oxaaole, or oxazoline, C3H5NO.
These are also formed when bromethylamine acts upon acid anhydrides or acid
amides ( Berichte, 22, 2221 ; 23, 2493).

/^-Methyl-oxazpline, C3H^ON(CH3), is an ojl, with an odor lik? .that of quino-
line. It forms salts with acids.

55 6 ORGANIC CHEMISTRY.

CLASS II.

AROMATIC COMPOUNDS OR BENZENE DERIVATIVES.

The aromatic compounds are mostly obtained from aromatic
oils and resins. They differ in various respects from the members
of the fatty or marsh gas series, but are principally distinguished
from the latter by their greater carbon content. The theoretical
representations upon their constitution are based chiefly on the
views developed by Kekul6 in 1865 — Kekule's benzene theory. The
views of this investigator are in brief as follows (compare Kekul6,
Lehrbuch der org. Chemie ; Annalen, 137, 129): —

1 . All aromatic compounds are derived from a nucleus consisting of six carbon
atoms ; its simplest compound is benzene, C^Hg. All other aromatic derivatives
may be obtained from the latter by substituting other atoms or atomic groups (side
chains) for its hydrogen atoms. The new derivatives are distinguished from the
methane compounds by their specific benzene character, and are, therefore, called
benzene derivatives.

2. Benzene has a symmetrical constitution. Each carbon atom is combined
virith one hydrogen atom. Differences between the individual C- and H-atoms
have not been discovered. Isomerides are, therefore, only possible when two or
more side-chains are present.

3. The structure of the benzene nucleus is such that the six carbon atoms, or
CH -groups, form a dosed, ring-shaped chain, the atoms being joined alternately

. by single and double bonds : — , ,

I I I I I I /^\

C=C— C=C— C=C or / V

I I % /~

In benzene, CjHj, the fourth affinity of each C-atom is joined to hydrogen; in
the benzene derivatives it is combined with other atomic groups.

Derivatives of Benzene. — These may be very readily derived
from benzene by the replacement of its hydrogen atoms. Those
derivatives in which side-chains exist are easily deprived of these
and then revert to benzene.

The closed chain is characterized by great stability, being torn
asunder, or dismembered in chemical reactions with great difficulty.
This is a property belonging to most all benzene derivatives ; it
distinguishes the latter from the methane derivatives. In external
properties they are better characterized, are more readily, crystal-
lized, and are more reactive than the fatty compounds.

The halogens and the nitro- and sulpho-groups can readily re-
place the hydrogen of benzene : —

C^H^Cl C.HJNO,) C.H^CSO,)!!.

C,H,C1, C,H^(NO,), CeH,(S03H),

DERIVATIVES OF BENZENE. 557

The union of the halogen atoms is much firmer in the benzene,
than in the methane derivatives ; as a general thing they cannot be
exchanged for other groups by double decomposition. The pro-
duction of nitro-compounds by the direct action of nitric acid is
characteristic of the benzene derivatives, whereas the fatty com-
pounds are generally oxidized and decomposed.

In the reduction of the nitro-derivatives we obtain the amido-
compounds . —

C.H^.NH, C,H,(NH,), C,H3(NH,),.

Amidobenzene. Diamidobenzene. Triamidobenzene.

The so-called azo-derivatives appear as intermediate products of
the reaction, whereas when nitrous acid acts on the amido-deriva-
tives the diazo-compounds result. Both classes are of exceptional
occurrence in the methane series (p. 167).

Benzene possesses a more negative character than the methane hydrocarbons.
The phenyl group, CjHj, stands, as it were, between the positive alkyls,
C n H2n + 1, and the negative acid radicals. This is evident from the slight basicity
of the phenylamines (like C^Hj.NH^), in comparison with the alkylamines.
Diphenylamine, (CgH5)2NH, is even a more feeble base, its salts being decom-
posed by water. Triphenylamine, (CgH5)3N, is not capable of yielding salts
{Berichle, 20, 534).

We discover the same in relation to the hydroxy! derivatives ; these, unlike the
alcohols, possess a more acid character. The phenols (such as C5H5.OH, carbolic
acid) readily form metallic derivatives with basic hydroxides; trioxy-benzene,
CgH3(OH)3 (Pyrogallic acid), reacts just like an acid.

By introducing hydroxyl for hydrogen into benzene we obtain
\he phenols, which may be compared to the alcohols : —

C.H^.OH CeH,(OH), CeH3(OH)3.

Phenol. . Dioxybenzene. Trioxybenzene.

These resemble the tertiary alcohols in having the group C. OH
attached to the three carbon affinities (p. 118), hence on oxidation
they cannot yield corresponding aldehydes, ketones or acids.

The entrance of hydrocarbon groups, CnHj^ + 1, into benzene
produces the homologues of the latter : —

C,H, C3H5.CH3 C^H^CH,), CeH3(CH3)3

Benzene. Methyl Benzene. Dimethyl Benzene. Trimethyl Benzene, «

C,H,.C,H, C3H,(C,H,), CeH C3H,.

Ethyl Benzene. Diethyl Benzene. Propyl Benzene.

Unsaturated hydrocarbons also exist : —

C.H^.CH^CH, CeH^CsCH, etc.

Ethenyl Benzene. Acetenyl Benzene.

In these hydrocarbons the benzene residue preserves the specific
properties of benzene; its hydrogen can readily be replaced by

558 ORGANIC CHEMISTRY.

halogens and the groups NO2 and SO3H. On the other hand, the
side-chains behave like the hydrocarbons of the fatty series ; their
hydrogen can be replaced by halogens, but not by (by action of
HNOs or HjSOi) the groups NO2 and SO3H. Different isomeric
derivatives are possible, depending upon whether the substitution
of the halogens (or other groups) has occurred in the benzene
residue or the side-chains, e. g. : —

CsH^Cl.CHj and CjH^.CHjCl.
CeH3Clj.CH3, CeH^Cl.CHjCl and CsHs.CHClj.

The halogen atoms in the benzene residue are very firmly com-
bined and mostly incapable of double decomposition, while those in
the side-chains react exactly as in the methane derivatives.

The substitution of hydroxy! for the hydrogen of the side-chains
leads to the true alcohols of the benzene series : —

C,H,.CH,.OH CeH,.CH,.CH,.OH C.H^C^^g^Qjj^

Benzyl Alcohol. Phenyl Ethyl Alcohol. Tolyl Alcohol.

Ta& primary class is oxidized to aldehydes dnd acids : —

C,H,.CHO CeH5.CH,.CH0 C,H,^^^3
Benzaldehyde. Phenyl Acetaldehyde. Tolyl Aldehyde.

The acids can be formed by introducing carboxyl groups directly
into benzene, or by oxidizing the homologues of the latter : —

C.H^.CO.H CeH^CO.H); C,H3(CO,H)3.

Benzene Carboxylic Acid. Benzene Dicarboxylic Acid. Benzene Tricarboxylic Acid.

^ i\C,0 H ^6n5.v-xi.2.<..W2n (..,5x1.3, ^Q jj .

Toluic Acid. Phenyl Acetic Acid. Mesitylenic Acid.

The hydrogen of the benzene residue in these acids, as well as in
the alcohols and aldehydes, is replaceable by halogens, and the
groups, NO2, SO3H, OH, etc.
'Furthermore, several benzene residues can unite directly, or
through the agency of individual carbon atoms, forming higher
hydrocarbons : —

CeHj CjH^.CH3 CgHj.CHj r h \

II II CH /^"«-

i.Hj C6H,.CH3 CeH,.CH, ^e^ls/

Diphenyl. Ditolyl. Dibenzyl. Diphenyl Methane.

Naphthalene. Anthracene. Chrysene,

DERIVATIVES OF BENZENE. 559

Structure of the Isomerides. — Numerous cases of isomerism are
possible among the derivatives of benzene. One variety of isomer-
ism corresponds exactly to that observed in the fatty series ; it is
founded in the isomerism of adjoining groups and their varying
union with the benzene residue or in the side-chain. Thus we have
the following isomerides of the hydrocarbon, C9H12 : —

C,H,.C3H, C,H,.C3H, . CeH,/^H3^ . Z,Vi.,{C,n^\.
Propyl Benzene. Isopropyl Benzene. Methyl Ethyl Benzene. Triraethyl Benzene.

The products obtained by substitution in the benzene residue
are isomeric with those derived by the same treatment of the side-
chains : —

CsHjCl^.CH-j CeH^CI.CH^Cl C5H5.CHCI2.

CeH^C^OH' CeH,.CH,.OH CeH^.O.CH,.

Cresol. Benzyl Alcohol. Phenyl Methyl Ether.

The following are also isomeric : —

P „ /OH ' „ „ /O.CH3 „ „ ,„„ n/OH

*-^6H4\C0,.CH3 ^="*\CO,H CsH3(CH3)/(.Q^jj, etc.

Oxybenzoic Ester. Methyl Oxybenzoic Acid. Oxytoluic Acid.

Another kind of isomerism is based upon the structure of the
benzene nucleus, and is conditioned by the relative positions of the
substituting groups, hence it is designated isomerism of position or
place.

All facts known at present argue with much certainty in favor of
the symmetrical structure of benzene, that is, that the six hydrogen
atoms, or more correctly the six affinities of the benzene nucleus
are of equal value (same as the four affinities of carbon). Let any
one hydrogen atom in benzene be replaced by another atom, or
atomic group, and every resulting compound can exist in but one
modification ; thus there is but one chlorbenzene, one nitrobenzene,
one araidobenzene, one toluene, one benzoic acid, etc. The fol-
lowing compounds are known in but one modification : —

C.H^Cl, C,H5(N0,), CeH,.NH,, -C.-R^.CB.,, CeH,.CO,H, etc.

The equal value of the six affinities is indicated not only by tlie fact that no
mono-derivatives, CgH^X, can be prepared in more than one modification, but it
can be directly proved. Thus in benzene four different hydrogen atoms (i, 2, 3, 4)
are replaced by hydroxyl; in each case but one and the same phenol, C5H5.OH, ^
results (Ladenburg, Berichte, 7, 1684). And since two similar ortho- and meta-
positions exist in benzene (2^6 and 3 ^ 5, p. 561), the six affinities of the ben-
zene nucleus must be equivalent.

S6o ORGANIC CHEMISTRY.

4 Owing to this symmetry of the benzene nucleus,

consisting of six carbon atoms, it can be repre-
sented by a regular hexagon ; the numbers represent
the six afiSnities, which in benzene compounds are
saturated by other atoms or other groups.*

Now, although the six hydrogen atoms in benzene
are equal in value, it is obvious from the graphic
representation that every di-derivative, CeHiXj, can
exist in three modifications; their isomerism is dependent upon
or due to the relative position of the two substituting groups.
Indeed, nearly all di-derivatives are known in three modifications,
but none in more than three. Thus, there are three dioxybenzenes,
three bromnitro-benzenes, three oxybenzoic acids, three toluenes,
three dimethyl benzenes, three dicarboxylic acids, etc. The fol-
lowing compounds are known in three modifications each : —

C H /OH C H /^"^ r H /^"^ C H /CO,H

The compounds of the above series can be" transformed into each
other by various reactions ; and, indeed, so that each of the three
isomeric modifications (in normal reaction) is transformed into the
corresponding modification of the other body. Three isomeric
series of di-derivatives of benzene consequently exist ; they are
designated as the ortho, meta, and para series. We call all those
or/y^^-compounds which belong to the series of phthalic acid ; the
meta or iso-compounds are those corresponding to isophthalic acid,
and para those which correspond to parabrombenzoic acid and
terephthalic acid.

That an isomeric modification really belongs to one of the three
series is determined in a purely empirical manner, either by di-
rectly or indirectly converting it into one of the three dicarboxy-
lic acids, C6H4(C02H)2 (phthalic, isophthalic and terephthalic

* The benzene formula of Kekul^, pictured on p. 556, representing the benzene
nucleus, does not fully express the equal value of the six affinities, because accord-

— ex. =CX

ing to them the combinations || and | or the positions (l : 2) and (i : 6)

— CX = CX
are different. According to theory and the formula there are four isomeric di-
derivatives, CgH^Xj, of benzene. But it has been proved that the di-derivatives
(1,2) and (1,6) are identical, and that only three isomeric di-derivatives are pos-
sible (p. 562). The hexagon does not attempt an explanation of the manner in
which the fourth affinity of the C-atoms is combined, but it does give full expres-
sion to the equal value of the six valences.

DERIVATIVES OF BENZENE. 56 1

acid). The relative positions of the substituting groups in the ben-
zene nucleus have, however, been ascertained with perfect cer-
tainty. In the ortho-compounds two adjoining hydrogen atoms
in benzene are replaced (the positions i : 2 or i : 6 ; i here repre-
sents any one of the six similar hydrogen atoms) ; the meta-com-
pounds have the structure, i : 3 or i : 5 ; whereas in the para-
compounds, two opposite affinities (separated by two carbon atoms)
are joined to other atoms (positions i : 4). The following graphic
representations will better explain the idea under consideration : —

Ortho-derivatives.

Meta-derivatives.
(1,3)

Para-derivatives,

(1,4)

The following substances may be mentioned as chief representa-
tives of the three isomeric series : —

C„H

/OH
■\0H

(I. 2).

Pyrocatechin.

(1.3).

Resorcin.

(1.4).

Hydroquinone.

C H /°^

Salicylic Acid. Oxybenzoic Acid. Paraoxybenzoic Acid.

Orthoxylene. Isoxylene. Paraxylene.

^6^4-^ CO^H Phthalic Acid. Isophthalic Acid. ' Terephthalic Acid.

The reasons for supposing that the isomeric di-derivatives possess a structure
such as indicated, are; —

(i) Phthahc acid is obtained by the oxidation of naphthalene, and the structure
of the latter (see this) is very probably such that the two carboxyl groups in the
acid resulting from it can only have the position (i, 2) (Graebe).

(2) The structure of mesitylene, C5H3{CH3)3, is symmetrical ; the three methyl
groups present in it hold the positions i, 3, S (see p. 566). The formation of mesi-
tylene by the condensation of three molecules of acetone (A. Baeyer) proves this ;
the substitutions of mesitylene (Ladenburg, Berichte, 7, 1133) also indicate it with
great certainty. The production of uvitic acid by the condensation of pyroracemic
acid (p. 566) argues for the view that in it, and consequently also in mesitylene,
the three side groups hold the positions (i, 3, 5). If we replace a CHj-group in
mesitylene by hydrogen, we obtain isoxylene, called dimethyl benzene, Cfi.Jy(^^^^,

47

562 ORGANIC CHEMISTRY.

in which the two methyl groups can only have the positions (i, 3) = (l, 5). When
isoxylene is oxidized, it yields isophthalic acid, C5H5(' rn^H-

(3) It is apparent, on examining the benzene hexagon, that only a single posi-
tion (4 with reference to l) is possible for the para-position while two similar posi-
tions can exist for the meta- and ortho-derivatives (the positions 3 and 5, and 2 and
6). This can be shown experimentally. It has been proved that the positions 3
and 5 are similar with reference to i, consequently the meta-derivatives (l, 3) and
(i, s) are identical {Annalen, 192, 206, 222, 68). In the same manner the ortho-
derivatives (l, 2) and (I, 6) are identical, conseqiiently the positions 2 and 6 are
similar (Berichle, 2, 141 and Annalen, 192, 213) — while the para-position occurs
but once in the benzene nucleus (see Berichte, 10, 1215). It has been shown that
paraoxybenzoic acid, parabromtoluene, and, therefore, also terephthalic occupy it.
The latest investigations upon oxy-methyl- ethyl benzonitrile show that the positions

2 and 6 are identical [Berichte, 18, Ref. 148), and from the study of bromnitro-
paratoluidine, it is concluded that this is also the case with the positions 3 and S
{Annalen, 234, 159).

In addition to the preceding we have another means of determining the
position, and it leads to exactly the same conclusions (Komer). If we replace
another hydrogen atom (by NOj) in a para compound, (e.g., paradibromben-
zene, CgH^Brj) it is evident from the figure that but one compound can result,
one nitroparadibrombenzene — because the positions 2, 3, 5 and 6 (those which
'the NO2 can enter) are alike with reference to the para position 1,4. But 3
isomeric mononitro derivatives are possible from metadibrombenzene (1,3); in these
the NOj-group occupies the positions 2, 4 {= 6) or 5. Orthodibrombenzene (i, 2)
finally can yield 2 mononitro-derivatives ; in these the NOj-group holds the positions

3 {== 6) and 4 (= 5). Therefore, six isomeric nitrodibrombenzenes, €5113;^ -g ^,

are possible ; ' derived from the para, 3 from the meta, and 2 from ortho-dibrom-
benzene ; conversely, by the retrogressive substitution of H for NO^ we discover
that paradibrombenzene is afforded by but one nitrodibrombenzene ; metadibrom-
benzene by three other nitrodibrombenzenes, and the ortho-compound by two nitro-
dibrombenzenes. Korner executed this method of ascertaining position with much
satisfaction and certainty with the isomeric tribrombenzenes ( Gazzetta chimica
Hal., 4, 305). The study of the six isomeric nitro- (or amido-) bejizoic acids,

CjHji^-^A^ , gave the same resvXis (Griesi, Berichte, z, 192 and 7, 1223).

V (iNU2j2

Further evidence is derived from the derivatives of the three isomeric xylenes :
metaxylene yields three nitroxylenes, three xylidines and three xylenols, the ortho-
xylene two of each, and the para- but one. From this isoxylene and isophthalic
acid must have the positions (l, 3),orthoxylene and phthalic acid (1, 2) andpara-
xylene and terephthalic acid (l, 4) [Berichte, 18, 2687).

That two adjacent carbon atoms of the benzene nucleus carry the side-groups in
the ortho compounds is further concluded from their ability to yield so-called con-
densations and various anhydrides (compare the phenylene diamines, thioanilines,
coumarines, indols, phthalic acid anhydrides, etc). There are also crystallographic
grounds favoring the idea that the meta-compounds stand between those of the
ortho and para series [Zeitschrift f. Kryst,, 1879, 171).

The benzene hexagon Hot only expresses all the relations of isomerism of the
benzene derivatives, bat also abundantly illustrates their chemical and physical
deportment.

CONSTITUTION OF THE BENZENE NUCLEUS. 563

If three or more hydrogen atgms of benzene be replaced, two
cases arise : the substituting groups are like or unlike. In the first
instance three isomerides of the tri-derivatives, e. g., C6Ha(CH3)3,
are possible, and they occupy the positions: —

(1,2,3) (1,2,4) and (i, 3, S).

We call them adjacent (i, 2, 3) or (v) = vicinal, unsymmetrical
(i, 2, 4) or (a) = asymmetrical, and symmetrical (i, 3, 5) or (j)
tri-derivatives.

Three isomeric structural cases exist likewise for the tetra-derivatives, with four
similar groups, C^H^'^^ (analogous to the di-derivatives) : —

(I.?, 3, 4) (1,2,4.5) (1,2,3,5).
Adjacent. Symmetrical. Unsymmetrical.

Only one modification is possible when there are five and six similar groups ;
thus there exists but one pentachlorbenzene, C„HC1,, and but one hexachloride,
C,C1,.

When the substituting groups are unlike, the number of possible isomerides is
far greater; they can easily be derived from the hexagon scheme. Thus, six iso-
meric modifications correspond to the formula of dinitrobenzoic acid, Cg H3(N02)2.
COgH ; —

(1,2,3) (1,2,4) (1,2,5) (1,^6) (1,3,4) (1,3,5);

here the carboxyl group occupies position i.

CONSTITUTION OF THE BENZENE NUCLEUS.

In Kekul6's formula the six carbon atoms are attached to each other by alter-
nating single and double bonds, forming a closed ring, consisting of three single
and three divalent ethylene linkages (p. 556). These assumptions give a rather
comprehensive view of the entire behavior of the benzene derivatives : —

1. They illustrate in the clearest manner possible the methods that have been
employed in the synthesis of benzene derivatives (p. 565), benzene condensations,
naphthalene, phenanthrene, etc. This has all been verified by the most recent
syntheses (that of a-naphthol from phenylisocrotonic acid, etc),

2. They show that only ortho-derivatives (because their side-chains are adja-
cent) are capable of forming anhydrides, and explain many derivatives due to
ortho-condensations. The accepted benzene formula is made quite evident from
the manner in which the quinoline ring is formed (Marckwald, Berichte, 23,
lois).

3. The assumption of three double unions offers the simplest explanation (with-
out new theories) for the power of benzene derivatives to yield additive products
with 2, 4 and 5 affinities (p. 567). True, this addition does not occur as readily
with the normal benzene compounds as it does with the methane compounds, in
which there exist ethylene unions, but it can be expressed by the ring-formula of
the benzene nucleus, and finds analogy in the behavior of the double (divalent)
union in phenanthrene (p. 568 and Baeyer, Annalen, 251, and 286). Para-
additions, it seems, do occur. These are not easily explained. The normal for-
mula only accounts for ortho-additions (p. 568).

4. Various physical properties argue for the presence of double unions, like
those of ethylene, in benzene. Thus, the specific refractive powers indicate the

564 ORGANIC CHEMISTRY.

presence of- three ethylene unions, CH=:CH, in benzene compounds, and five in
naphthalene (Brilhl, Berichte, 20, 2288). Compare Nasini, Berichte, 23, Ref. 276.
The specific volumes of the benzene derivatives appear to support this idea (p. 57
and Berichte, 20, 771).

KekulS's formula for benzene does not fully express the entire symmetry of the
benzene nucleus. It would make the ortho-derivatives (l, 2) and (l, 5) different,
and allow of four different di-derivatives, unless we admit Kekule's idea of the
oscillations of the adjacent carbon atoms [Annalen, 162, 86)

For this and other reasons various benzene formulas have been proposed (see G.
Schultz's Chemie des Steinkohlentheers, II Aufl., p. no), e. ^., the octahedral
formula of Thomsen, the prism formula of Ladenburg, and the diagonal formula
of Claus.

The authors of these three formulas do not regard double unions as present in
the normal benzene nucleus, but contend that each carbon atom is united by a
single bond to three other carbon atoms. The benzene nucleus, according to this
view, contains nine single unions of carbon : —

CH CH

HC i^-^TN CH

and

HC

CH CH

CH

It was thought that this last idea was definitely proved by the specific volumes
of the benzene derivatives, and especially by their heat of combustion (Theorie
der Bildungswarme von J. Thomsen, Berichte, 13, 1808 ; 14, 2944). According
to. the most recent researches the specific volumes argue strongly for the presence
of three divalent unions in the benzene nucleus, while the conclusions drawn from
the heat of combustion are in the opinion of Briihl unfounded [Journ. prakt.
Chemie {2) Bd., 35, l).

Ladenburg's prism formula fully accounts for all the static relations of ben-
zene, and explains its isomeric derivatives. It, however, ignores all the double
unions, which are proved by the partially reduced benzene nuclei of the di- and
tetra-hydro-additive products (p. $68). It establishes a spatial orientation of
the four affinities of the carbon atoms, which is without analogy in the paraffin
series, and, in the opinion of its author, leaves to the formula of Kekule the first
place in explaining the various modes of formation and the decompositions of the
benzene compounds (^Berichte, 23, loio).

The diagonal formula of A. Claus, with its hexagonal ring and its diagonal or
central linkages, explains all the isomeric relations of the derivatives of benzene
fully as well as the hexagon formula. It has the advantage that it permits of the
formation of either para- or ortho-additive products, because it grants the double
carbon-linkages in both the di- and tetra-hydro-benzenes {Berichte, 20, 1422;
Journ.pr. Chem. (2)142,458). But it also presents an orientation of the four
carbon affinities that is without analogy, and introduces a peculiar central valence,
differing from that of the two ring valences.

Baeyer has very recently introduced a central formula, which is very similar to
the diagonal formula, but, unlike the latter, does not admit the presence of central
linkages. It does not attempt to account for the state or condition of the fourth
valence of carbon, but maintains merely that it exerts a pressure directed towards
the centre. It thus reverts to the hexagonal formula of benzene (Kekul^) which

CONSTITUTION OF THE BENZENE NUCLEUS. 565

makes no attempt to explain the manner in which the fourth valences are com-
bined (Baeyer, Berichte, 23, 1775).

Formation of Benzene Derivatives. — The compounds of benzene
can only be obtained in exceptional cases from methane derivatives
by synthetic reactions. As they are generally very stable on expo-
sure to heat (especially the hydrocarbons and anilines), they are
quite often produced by the application of a red heat to the methane
derivatives. Thus, benzene and other hydrocarbons result by ex-
posing acetylene to a red heat : —

3^2112 = CgHg; 4C2H2 = CgH8.

Benzene. Styrolene.

1. Liquid bromacetylene is readily polymerized, when exposed
to light, to solid symmetrical tribrombenzene {Berichte, i8, Ref.

374) :—

3C2HBr = C6H3Br3(l,3,S) or

HC = CBr HC = CBr

/ \

BrC CH yield BrC CH.

\\\ ///• \ //

HC CBr HC — CBr

When iodo-acetylene, CjHI, is preserved for some time it also
becomes tri-iodobenzene, C6H3I3. When di-iodoacetylene, CJj, is
exposed to light or heat, it forms hexa-iodo-benzene, Q.^^ {Be-
richte, 18, 2276).

Symmetrical trimethyl benzene (mesitylene) is similarly ob-
tained from allylene, CH3. C • CH, on distilling its sulphuric acid
solution : —

3CH:C.CH3=C, H3(CH3)3.

The polymerization of crotonylene, CHj.C- C.CH3 (p. 89), occurs even more
readily, since shaking it with sulphuric acid suffices for its conversion into hexa-
methyl benzene, CijHu {Berichte, 14, 2073) : —

3CH3.C:C.CH3 = Ce(CH3)e.

The transposition of propiolic acid (p. 244), when exposed to light, into trimesic
acid (symmetrical benzene tricarboxylic acid {Berichte, ig, 2185) is due to the
same polymerization : —

SHC-jC.CO^H = CeH3(C02H)3 (i, 3, 5).

2. The formation of benzene compounds from ketones (by hydro-
lytic condensation) is very interesting. The condensation here is
probably analogous to that of crotonaldehyde from aldehyde (p.
194), and mesityl oxide from acetone (p. 207). Symmetrical tri-
methyl benzene (mesitylene) is formed rather abundantly on dis-
tilling acetone with sulphuric acid : — •

CHj

\
CO

CH3

/

CH,

\

co-

-CH

CO-

-CH3

/
CH3

3 Molecules Acetone.

566 ORGANIC CHEMISTRY.

3CO(CH3)2 = CeH3(CH3)3 + 3H,0, or

CH3

\
C=CH

/ \ .
yield HC C— CHj + sH^O.

C— CH

/
CH3

I Molecule Mesltylene.

We can obtain in a similar manner symmetrical triethyl benzene, C8H3(CjH5)3,
from methyl-ethyl ketone, CHg.CO.C^Hj, tripropyl benzene, CgH2(C3Hj)3,
from methyl-propyl ketone, CH3.CO.C3H J, and triphenyl benzene, C5H3(CgH5)3,
from methyl-phenyl ketone, CH3.CO.CgH5.

Analogous condensations are the following : —

Formo-acetic ester, CHO.CH^.COjR, to trimesic ester, C5H3(C02R)3 ; acet-
aldehyde to symmetrical triacetyl benzene, CjH3(CO.CH3)3 (p. 323) ; pyroracemic
acid to uvitic acid, C5H3.(CH3).(C02H)2 (reduction of the carboxyl group to
CH3) ; aceton-oxalic ester to symmetrical oxytoluic acid, CjH3(CHg)(OH)C02H

(P-341)-

Another rather remarkable condensation is that of the ortho-diketones to
quinogens and quinones (p. 326).

3. Another synthetic method employed in the production of
benzene derivatives depends upon condensation, analogous to that
observed in the formation of aceto-acetic ester (p. 334). It occurs
in the action of sodium upon various acid esters, when sodium
ethylate or alcohol is split off, and, therefore, may be termed an ■
ester condensation.

Succino-succinic ester (quinone tetrahydro-dicarboxylic ester) (p. 342) is formed
by the action of sodium upon ethyl succinic ester : —

ROaC.CHj + RO.CO.CH2 = RO2C.CH.CO.CH2

I I II +2ROH.

CH^.CO.OR CHj.COjR CH^.CO.CH.CO^R

Again, upon heating sodium malonic ester phloroglucintricarboxylic ester re-
sults (p. 409) : —

ROj.CCHNa RO.CO.CHNa.COjR

I CHNa.CO.OR

CO.OR I = CO.CH.dO +3R0Na.

COjR I

CO^R

3 Molecules Sodium Malonic Ester. Phloroglucin-

tricarboxylic Ester.

Similarly, acetone dicarboxylic ester yields, on heating its sodium compound,
dioxyphenylaceto-dicarboxylic ester, which can easily be converted into orcinol
{Berichte, ig, 1446) : —

^KchSr = CeH30,{g^^;g^^ +ROH + HA
In this reaction there occurs first an ester, then a ketone condensation.
The ester of trimesic acid is produced when sodium acts upon a mixture of

ADDITIVE PRODUCTS. 567

acetic ester and formic ester, water and sodium ethylate splitting oif at the same
time.

4. When hexyl iodide, CgHuI, and ICI3 are heated together the two terminal
C-atoms unite, and the product is hexachlorbenzene, CgCl^, and when heated with
bromine hexabrombenzene results, even at 200° C.

Another interesting synthesis is that of benzene hexacarboxylic acid,
(C5(C02H)5) = Cj jHgOi 2, mellitic acid, by the oxidation of graphite or charcoal
with potassium permanganate, and that of the potassium derivative of hexaoxyben-
zene, Cg(OH)8,upon heating CO with potassium (Nietzki, Berichte, 18, 1836) : —

6C0 + 6H = C^OsHj.

The normal benzene nucleus, formed as above, is very stable. It is broken
only when exposed to exceptionally energetic reactions. The following decompo-
sitions are effected quite readily, and are, therefore, worthy of mention : the con-
version of proto-catechuic acid and pyrocatechol into dioxytartaric acid by nitrous
acid ; benzene into trichloraceto-acrylic acid and maleic acid (p. 344) by cliloric
acid, and gallic acid, salicylic acid and phenol into isotrichlorglyceric acid (p.
461). Chlorine changes phlorglucin quite easily into dichloracetic acid and tetra-
chloracetone (p. 205), while potassium chlorate and hydrochloric acid decompose
chloranilic acid into tetrachloracetone and tetrachlordiacetyl (p. 327).

The intermediate transposition of various chlorine derivatives, by the action of
chlorine, into keto-derivatives of pentamethylene is rather peculiar (p. 520).

All benzene compounds are decomposed when oxidized by energetic reagents,
such as chromic acid, etc.

Additive Products. — Many benzene derivatives are able to com-
bine directly with 2, 4 and 6 atoms of chlorine, bromine, hydro-
gen, etc. Here the three double bonds of the carbon atoms, as in
the ethylenes, in all probability, change to single bonds : —

CgHg.Clj C5H5.CI4 CjHj.Cls.

Nascent hydrogen converts the phthalic acids into di-, tetra, and
hexa-hydrophthalic acids. The halogens are added with much more
difficulty than in the case of the alkylens and other unsaturated
fat-bodies, although the latter sometimes take up the halogens with
difficulty (see fumaric acid). These addition products contain the
ring-shaped, closed benzene chain, and are the compounds, CeXij,
no longer able to saturate additional affinities. When the benzene
ring is broken, hexane derivatives, CjXu result. The addition
products are, therefore, true benzene derivatives, and can readily
be converted into the normal compounds, CjXs (p. 571). . .

The latest researches of Baeyer prove that hexa hydrobenzene,CjH5.H5, is in
fact identical with hexamethylene (analogous to tetra- and penta-methylene)
(Baeyer, Annalen, 245, 131 ; Berichte, 21, Ref. 495) : —

568 ORGANIC CHEMISTRY.

Baeyer designates the normal benzenering, C^Hj, in which each C-atom is com-
bined with three affinities to carbon, as the tertiary benzene ring, the added ring,
- CjH, 2, as the secondary or reduced benzene ring.

The partially reduced rings, CjHg.Xj and CgH^.X^, contain one and two
double-unions, C^C, which behave just like those of the defines. Like the
latter, they are readily oxidized by alkaline permanganate, whereas terephthalic
acid is not attacked in the cold by this reagent. It might be deduced from this
that an ordinary double-union does not occur in the normal benzene ring ; fur-
ther, that para-compounds also occur, as the additions sometimes take place at the
para carbon atoms. Baeyer, however, thinks that these abnormalities are ex-
plained by the like deportment of phenanthrene (the non-oxidation of its double-
linkage) and by the molecular transpositions of the hydrogen additive products
{Annalen, 251, 258; 256, 1, Berichte, 22, Ref. 375; 23, 23I ; 23, 1272).

The additions to the ortho-, para, and meta-carbon atoms occur more con-
veniently if we adopt the diagonal formula of Claus {Jr. pk. Chem. 42, 461 ;
herichte, 20, 1424).

Baeyer indicates the double-union in the reduced benzene nuclei, CjHg.Xj and
CgHg.X^, by the character A, adding a number as index to show which carbon
atom pf the hexagon (p. 560) is in double union with the adjacent (next following)
carbon atom. Thus, A', '-Dihydro-terephthalic acid represents a para-dicarboxylic
acid in which the second C-atom is doubly united with the third C-atom, and the
fifth C-atom doubly linked to the sixth C-atom. A'-Tetrahydro-terephthalic acid
is a substance in which the second carbon atom is doubly linked to the third
carbon atom : —

COjH.HC('^|][ ^ ^g'^CH.COjH, A«, '-Dihydroterephthalic acid.
COjH.Hc/^^ ^ CH /CH.COjH, A8.Tetrahydroterephthalic acid.

A. Baeyer has developed stereochemical representations as to the constitution of
hexa-hydro-benzene derivatives. These would explain the existence of two
isomeric hexa-hydroterephthalic acids, two hexahydromellitic acids, etc. (Baeyer,
Annalen, 258, 1, 145.) See also Sachse, Berichte, 23, 1363 (compare Herrmann,
Berichte, 23, 2060).

HYDROCARBONS, C„H,„^.

The benzene homologues are formed by substituting alkyls in
benzene for hydrogen : —

C,H, CeHj.CH, C,H^(CH3), C,H3fCH3)3 CeH,(CH,),

Benzene. Toluene. Xylenes. Trimethyl Benzenes. Durene.

B. P. 8o.s°. 110°. 137-140°. 163-170°. 190°.

C6H5.C2H5 C5H5.C3H, CjHj.CgH, CgHe.CiHg.

Ethyl Benzene- Propyl Benzene. Isopropyl Benzene. Isobutyl Benzene.

134°. 157°. 151°. ■ 163°-

The entrance of the methyl group into the benzene nucleus
elevates the boiling point about 29-26° ; its introduction in the
side-chains causes an increase of about 23-19°. The boiling points
of isomerides of position (p. 559) usually lie near each other; the
ortho-compounds boil about 5°, and the meta- 1° higher than the
para-derivatives.

HYDROCARBONS. 569

Preparation. — The most important methods of preparing the
benzene hydrocarbons are the following : —

(i) Action of sodium upon mixtures of their bromides, and the
bromides or the iodides of the alkyls in ethereal solution ; reaction
of Fittig (p. 72) : —

CgHjEr + CH3I + 2Na = CeHj.CHj + Nal + NaBr,

CjH^Br.CjHj + C2H3I + 2Na = CeH^/^^l^s + Nal + NaBr.

In carrying out these syntheses mix the bromide with the alkyl iodide and ether
(free from water and alcohol) , then add metallic sodium in thin pieces and allow to
stand for some time, after which the solution is heated with a return condenser
upon a water bath. A few drops of acetic ether sometimes accelerates the re-
action. Para- and ortho-derivatives, e. g., CjH^Br.CHj and C^H^Brj, react
most readily. With the metacompounds, which are not so easily attacked, bro-
mides are substiuted for alkyl iodides, or else benzene iodides are employed. (See
Berichte, 21, 3185, for the course of the reaction.)

(2) Action of the alkylogens upon benzene hydrocarbons in
the presence of aluminium chloride (zinc or ferric chloride) —
Friedela.nA Crafts.

It is very likely that in this reaction metallo-organic compounds, n. g., CjHj,
AljClj, are formed, which afterwards act upon the alkylogens : —

CgHg + CHjCl = CeH^.CH, + HCl,
C5H, + 2CH3CI = CeH^(CH3), + 2HCI, etc.

• Even hexamethyl benzene, Cj(CH3)s, can be prepared after this manner.
Various halogen derivatives, e. g., chloroform (see diphenyl methane) and acid
chlorides (see ketones) react similarly with the hydrocarbons of the benzene
series.

To effect syntheses after this style, AlClj (^— ^ part) is added to benzene, and
CH3CI or C2H5CI is conducted into the heated mixture; or AICI3 can be added
to the benzene compound mixed with the chloride or bromide, and heat then
applied until the evolution of HCl has almost ceased (Berichte, 16, 1745). Car-
bon disulphide sometimes acts very favorably a,s a diluent. The product is grad-
ually mixed with water, then digested with soda. The oil which separates is
subjected to distillation. Consult Berichte, 14, 2624, upon the introduction of methyl
into homologous benzenes. A table of all the syntheses effected by AICI3 may be
found in Annalen Chim. Phys., (6) I, 449.

Frequently the action of the AICI3 is much more complicated, inasmuch as
syntheses are not the only products, but we also find decompositions, splitling-off
and transference of the alkyls. Thus, from toluene we obtain benzene, xylene,
etc., (Anschiitz, Berichte, 18, 338, 657 ; Friedel, Berichte, 18, Ref. 336). A tabu-
lation of the more complex reactions can be found in Annalen, 235, 150, 299.

The benzene nucleus may be alkylized if the HCl-salts of-alkylic anilines be
heated alone, or if the anilines and methyl alcohol be heated to 250-300° ; here
the NH2 group is eliminated {Berichte, 13, 1729) ; or the anilines and fatty alco-
hols can be heated with zinc chloride to 250° {Berichte, 16, 105) :-

C
48

^H^.NH^ + qH^.OH = C^H,/^^^^^ + H,0.

57© ORGANIC CHEMISTRY.

Homologues of phenol (see these) are produced by heating fatty alcohols,
phenol and zinc chloride together. The easy formation of isobutyl benzene on
heating benzene and isobutyl alcohol with ZnCl^, deserves notice.

(3) Dry distillation of a mixture of aromatic acids with lime or
soda-lime (p. 71); iron filings are introduced to accelerate the
conduction of heat. All the carboxyl groups are split off in the
reaction and the original hydrocarbons set free : —

CgH^.COjH = C5H5 + CO2,
C„Hi(CO,H), = CeHe + 2CO,,
C,H,(CH3).CO,H = CeH^.CH, + CO,.

(4) Heating the oxygen derivatives, e. g., phenols and ketones, with zinc dust,
or with hydriodic acid and phosphorus. It is remarliable, that benzophenone,
CgH5.CO.CgH5, for example, is readily reduced, while the opposite is true of
diphenyl ether, C6H5.O.C5H5.

(5) The methods of obtaining benzenes synthetically from fatty compounds,
especially acetylenes and ketones, have already received notice (p. 566).

(7) Dry distillation of various, non-volatile carbon compounds, e. g., wood,
resins, bituminous shales, and especially bituminous coal. When the vapors of
volatile methane derivatives (CH^, alcohol, ether) are conducted through tubes
heated to redness, they set hydrogen free and yield acetylene, benzene and its
homologues, styrolene, CjHg, naphthalene, CgHu, anthracene, etc. Petroleum
and the tar from lignite, containing ethane hydrocarbons, do the same. A similar
behavior is observed with a mixture of benzene vapor and ethylene (^Berichle, 20,
660).

The chief and almost exclusive material in preparing benzene
hydrocarbons is coal tar, which is made in such large quantities in
the manufacture of gas. Distillation divides the tar into a light and
heavy oW.. The former boils from 60-180° and contains principally
benzene, toluene, the three xylenes and trimethyl benzenes, as well
as durene. As to their formation see Berichte, 18, 3092 ; ig,
2513-

To isolate these hydrocarbons, shake the light oil first with sulphuric acid, then
with potash; wash, dry and finally fractionate over sodium. The heavy oil, boil-
ing from 160-220°, sinks in water and comprises mainly phenol, cresol and naph-
thalene. In the portions of coal tar boiling at high temperatures, we have the
sohd hydrocarbons ; naphthalene, C,gHj, acenaphthene, Cj^Hjj, anthracene and
phenanthrene, Cj^Hj,,, pyrene, CijHjg, chrysene, CjjHjj, and others. Some ben-
zene hydrocarbons occur already formed in small amount in the naphtha varieties
(p. 78) (for their recognition by means of bromine and AlBrj, see Berichte, 16,
2295), and in different ethereal oils (together with aldehydes, alcohols and acids).

Phenols, benzene, and its homologues (see Cymene, p. 577) are obtained by dis-
tilling camphor with zinc chloride, or phosphorus sulphide.

Properties. — The hydrocarbons of the benzene series are volatile
liquids, insoluble in water, but soluble in alcohol and ether ; some,
containing only methyl groups, are solids at ordinary temperatures.
They dissolve in concentrated sulphuric acid, on application of

BENZENE. 571

heat, to form sulphonic acids, e. g. , CeHs.SOsH, from which the
hydrocarbons can be reformed by dry distillation or by heating
with concentrated hydrochloric acid (see benzene sulphonic acids).
This reaction is the basis of a method for the separation of the ben-
zenes and marsh gas series ; it also permits of the preparation of the
former in pure form. The benzenes dissolve in concentrated nitric
acid, forming nitro-derivatives.

Acids are produced (aromatic acids) by oxidizing the side-chains
of homologous benzenes with nitric acid, a chromic acid mixture,
potassium permanganate, or ferricyanide of potassium. Energetic
oxidation converts benzene into carbon dioxide; only minute
quantities of benzoic and phthalic acids are formed at the time.

Chromyl chloride, CrOjCla, unites with the benzene homologues
to form compounds which water converts into aromatic aldehydes
(see these).

HYDROBENZENES, OR BENZENE HYDRIDES.

The normal benzenes can take 2, 4 and 6 hydrogen atoms, forming additive
products (p. 567).

When heated with phosphonium iodide, they mostly yield the lower hydrides ;
thus, toluene yields the dihydride, CyHj.H^, isoxylene, the tetrahydride, CjHj„.Hj,
and mesitylene, the hexahydride, CgHj2.H5; nearly all the benzenes, when
acted on with hydriodic acid at 300° finally yield the hexahydrides. The latter
are, in all probability, the so-called naphthenes, which have been isolated from
Caucasian petroleum {Berichie, 23, Ref. 431). They are closely allied to the
paraffins, boil about 12° lower than their corresponding normal benzenes, and are
very slowly attacked by cold, alkaline permanganate. The partial benzene hy-
drides, CgHj, and CjHu.are readily oxidized by permanganate, and take up bro-
mine with great ease (Berichte, 21, 836).

The benzene hydrides dissolve upon shaking them with fuming sulphuric acid,
with liberation of carbon dioxide and sulphur dioxide, and the formation of sulpho-
acids of the normal benzenes. For example, octonaphthene, CgHj 5, yields w-xylene
sulphonic acid. But other oxidizing agents frequently separate the added hydrogen
Tatoms, or the hydride is completely destroyed. Fuming nitric acid, or nitro-sul-
phuric acid, dissolves them in small amount (5 per cent.) to form nitro-derivatives
of the normal benzenes. They are mostly burnt upon the application of heat
{Berichte, 20, 1850). Many benzene hydrides precipitate metallic silver from
boiling solutions of silver nitrate.

I. Benzene, CeHs, contained in coal tar, is formed by the dry
distillation of all benzene acids, having only CO2H side groups (p.

57°)-

That portion of the coal tar boiling from 80-85' '^ chilled by means of a freezing
mixture, and the solid benzene then pressed out in the cold. To get perfectly pure
benzene, distil a mixture of benzoic acid (l part) and CaO (3 parts).

572 ORGANIC CHEMISTRY.

Common benzene from coal tar, even the purified article, invariably contains
thiophene, C^H^S; hence it yields the indophenin reaction (p. 529). When
heated with sodium it gives the reaction of Na^S. Concentrated sulphuric acid
turns it brown, and when the acid contains N2O3, the coloration is violet {Berichte,
16, 1473)-

Benzene is a mobile, ethereal-smelling liquid, of specific gravity
0.899 ^' °° (°-8799 at 20°). It solidifies about 0°, melts at +6°,
and boils at 80.5°. It burns with a luminous flame, mixes with
absolute alcohol and ether, and readily dissolves resins, fats, sulphur,
iodine and phosphorus.

Benzene Hexahydride, CgHg.Hg, Hexamethylene (see above), boils at 69°;
its specific gravity at 0° is 0.76.

2. Toluene, QHg == CeHs.CHg, is obtained from coal tar, and
is produced in the dry distillation of tolu balsam and many resins.
It is synthetically prepared by the action of sodium upon CeHjBr

and CH3I, and by the distillation of toluic acid, CeH^^ ^q tt,

with lime. It is very similar to benzene, boils at 110°. 3, and has a
specific gravity at 0° erf 0.882 (0.8656 at 20°). It does not solidify
at — 28°. Dilute nitric acid and chromic acid oxidize it to ben-
zoic acid, CsHs. COOH ; chromyl chloride converts it into benz-
aldehyde.

Ordinary, not perfectly pure, toluene contains some thiotolene, hence gives the
anthraquinone reaction (p. 529) [^Berichte, 17, 1338).

Toluene Dihydride, CjHg.Hj, boils at 105-108°. Toluene Hexahydride,
CjHj.Hj, boils at 97° ; sp. gr. 0.772 at 0°.

3. Hydrocarbons, CsHu : —

C,Hj(CH3)j CgH-.C^Hj.

3 Isomerides. i Modification.

The three dimethyl benzenes, C6H4(CH3)2, or methyl toluenes
(ortho, meta and para), are called

Xylenes, and occur in coal tar. Orthoxylene, with a little of
the para variety, is produced on conducting CH3CI into benzene
or toluene containing AICI3 (p. 569) {Berichte, 14, 2627).

That portion of coal tar oil boiling between 136-14.1° contains, in addition to
ten per cent, paraffins, variable quantities of metaxylene (as much as 85 per cent.),
paraxylene (as high as 20 per cent.), and orthoxylene (up to 20 per cent.). When
the mixture is boiled with dilute nitric acid (i part NO3H and 3 parts H^O) the
ortho- and para- varieties are oxidized to their corresponding toluic acids, C5H4
(CH3).C02H, while metaxylene and the paraffins are unattacked. On shaking
crude xylene with ordinary sulphuric acid, the ortho- and meta- xylenes dissolve
to form sulphonic acids. Only metaxylene is dissolved if 80 per cent, sulphuric
acid be used. Sodium orthoxylenesulphonate is sparingly soluble in water. Para-
xylene only dissolves in fumjng sulphuric acid. It also volatilizes first when
crude xylene is distilled with steam (Berichte, 10, 1013; 14, 2625; 17,- 444).

ETHYL BENZENE. 573

1. Orthoxylene (i, 2) is obtained from orthobrom-toluene by means of CH3I
and sodium, and can be prepared from toluene by means of CH3CI and AICI3
(Berichte, 14, 2628). Metaxylene is formed at the same time (Berichte, 18, 342).
It boils at 142-143°. Dilute nitric acid oxidizes it to toluic acid, CgHj(CH3).
CO^H ; chromic acid decomposes it into carbon dioxidp, and with potassium per-
manganate it yields phthalic acid (^Berichte, 19, 3084).

Ortho-xylene can be nitrated by heating it for some time (6-8 hours) with a
mixture of NO3H and S'O^H^. Bromine, at 150°, converts it into ortho-xylene
bromide, CgH4(CH2Br')2, which melts at 94° {Berichte, 17, 123). On heating
the three xylenes with PCI5 in a sealed tube chlorine first enters the side-chains
(Berichte, ig, Ref. 24). The resulting ortho-xylylene chloride, CgH4(CH2Cl)j,
has also been obtained from phthalyl alcohol. The latter melts at 54°, and boils
at 145° under a pressure of 20 mm.

o-Xylene Dihydride, CjHjj, is cantharene, obtained by heating cantharides
with PjSj. Its odor is like that of turpentine. It resinifies when exposed to the
air [Berichte, 19, 1406).

2. Metaxylene, or Isoxylene (i, 3), is obtained from coal tar, and is pro-
duced from mesitylene, CjH3(CH3)3 (l, 3, 5), by heating mesitylenic acid,

,f^A > , with lime. It could not be prepared from metabroratoluene,

CgHjBr.CHj, but was obtained in small quantity from meta-iodo-toluene. It boils
at 137°; its specific gravity at 0° is 0.878. It is not oxidized by ordinary nitric
acid as readily as paraxylene, and yields isophthalic ^cid, C fi.^{<ZO^\. Iso-
toluic and isophthalic acids result from it by the action of KMnO^. The laydrides
are obtained by heating metaxylene or camphoric acid with HI or PH^I : CjHjj.Hj
and CgHio-Hg.

/«-Xylene Tetrahydride, boils at 119°.

OT-Xylene ITexahydride is identical with octonaphthene, from Caucasian
petroleum. It boils at 117-118°, and when acted upon with nitric and sulphuric
acids yields trinitro-isoxylene.

On warming metaxylene with fuming nitric acid a dinitro-product results, which
melts at 93°. S0^H2 and NO3H yield a ??-«K«"/ro-product, CgH(NOjj)3.(CH3)2 ;
this melts at 176°. Characteristic amido-compounds are obtained by the reduction
of the preceding nitro-derivatives. Cold, fuming nitric acid produces the inono-
nitro compound, which melts at -)- 2° and boils at 237-239°.

3. Paraxylene (l, 4) is formed when cainphor is distilled with ZnClj. It is ob-
tained pure by the action of sodium and CH3I upon parabromtoluene, CgH^Br.
CH3, or better, upon paradibrombenzene, CjH^Brj [Berichte, 10, 1356). It boils
af 136-137° ; its specific gravity at 19° is 0.862. Pure paraxylene solidifies in the
cold, forming monoclinic needles, which melt at 15°. Dilute nitric acid oxidizes
it first to paratoluic acid and subsequently to terephthalic acid, C3H4(C02H)2.
Chromic acid converts it immediately into the latter acid. With fuming nitric acid
it yields two isomeric dinitro-paraxylenes, CgH2(NOj)2(CH3l2 5 tli^ first melting
at 93°, the second, more sparingly soluble in alcohol, at 123.5°. NO3H and
HjSO^ convert it into a trinitro-derivative, CgH(N02)3(CH3)2, Which melts at
137°- The reduction of these compounds produces ill-defined amido-compounds.
Paraxylene is soluble in fuming sulphuric acid only ; its sulphonic acid forms large
crystals, and is not very soluble.

4. Ethyl Benzene, CgH5.C2H5, is produced by the action of sodium upon
CgHjBr and C2H5Br, and hydriodic acid upon styrolene, C8H5.C2H3, but best
by the action of C^H^Br and AICI3 upon benzene [Berichte, 22, 2662). It boils
at 134°. Its specific gravity at 22° equals 0.866. Dilute nitric acid and chromic
acid oxidize it to benzoic acid; CrO^Cl^ converts it into phenyl acetaldehyde,

It yields two liquid mononitro-products, C3H^(N02).(C2H5)

574 ORGANIC CHEMISTRY.

(i, 2) and (i, 4), by the action of fuming nitric acid. The first boils at 227°, the
second at 245°. See p. 586 for the halogen derivatives of ethyl benzene.

4. Hydrocarbons, C9H12.

CgH3(CHg)3 CgH^I^, jj CeHj.CjH,.

Trimethyl Benzenes. Methyl Ethyl Benzenes. Propyl Benzenes.

3 Isomerides. 3 Isomerides. 2 Isomerides.

(a) Trimethyl Benzenes.

I. Mesitylene, symmetrical trimethyl benzene, C6H3(CHs)3
(i, 3, 5), occurs in coal tar, and is produced by distilling acetone,
or allylene with sulphuric acid. It may, also, be prepared from
phorone (p. 566).

Preparation. — Distil a mixture of acetone (l volume) and sulphuric acid (l
volume) diluted with ^ volume of water. It is well also to add sand. The
distillate consists of two layers; the upper, oily layer is siphoned off, washed with
a soda solution and fractionated.

Mesitylene is an agreeable-smelling liquid, which boils at 163°.
When heated with dilute nitric acid the methyl groups are success-
ively oxidized to mesitylenic acid, uvitic acid and trimesic acid,
C6H3(C02H)3 (i, 3, 5). Chromic acid breaks it up, yielding acetic
acid. Heated up to 280° With PHiI we get the hexa-hydride,
CgHij.Hg, boiling at 138°, and yielding the same products as mesi-
tylene when oxidized. Warm fuming nitric acid converts it into
trinitroraesitylene.

Nitromesitylene, CgH]i(N02), is obtained by the nitration of mesitylene in
glacial acetic acid ; it melts at 44.°. Dinitromesitylene melts at 86°. The trinitro-
compoimd, obtained by adding mesitylene to a cold mixture of NO3H and SO^H^,
crystallizes from benzene in large, colorless needles. It dissolves in hot alcohol,
but not readily in ether, and melts at 232°.

C5H2C1(CH3)3 boils at 205°. 0311012(0113)3 melts at 59° and boils at 244°.
03013(0113)3 melts at 204°.

03H2Br(OH3)3 solidifies at 0° and boils at 225°. 03HBr2(CH3)3 melts at
60°, 03Br3(0H3)3at224°.

The symmetrical structure of mesitylene renders it impossible to have isomerides
in these substitution products [Annalen, 179, 163).

Bromine, acting upon boiling mesitylene, produces the bromides, 05113(0113)2.
OHjBr, 03H3(OH3)(OH2Br)2, and 03H3(0H2Br)3 ; the latter melts at 94°
{Berickte, ig, Ref. 25).

2. Pseudocumene, CgH3(OH3)3 (1, 3, 4), unsymmetrical trimethyl ben-
zene, occurs with mesitylene in coal tar (boiling at 162-168°) in about equal
amount. It cannot, however, be separated by fractional distillation.

To separate these two hydrocarbons, dissolve the mixture in concentrated sul-
phuric acid and dilute with water, when the more sparingly soluble cumene-
sulphonic acid will separate in the form of crystals, while mesitylene-sulphonic
acid continues in solution {JSericAU, g, 258). The hydrocarbons are obtained by
heating the sulpho-acids with hydrochloric acid to 175° (p. 571 ).

It may be synthesized by the action of sodium and OH 3 1 upon bromparaxylene
(i, 4) and brom-metaxylene (i, 3), hence the structure (i, 3, 4). It appears in

ISOPROPYL BENZENE. 57S

small quantities when phorone is heated with PjOj or ZuClj. Pseudocumene
boils at i66°. Nitric acid oxidizes it to xylic acid, so-called paraxylic acid, and
finally to xylidic acid, C5H3(CH3)(C02H)j (see these).

A mixture of NO3H and HjSO^ converts pseudocumene into a trinitro-com-
pound, Cg(N02)3.(CH3l3, which is not very soluble in alcohol, but crystallizes
from benzene in thick prisms, melting at 185°. It yields, by reduction with hjdro-
gen sulphide, nitro-cumidine sulphonic acid (Berichte, 20, 966). The gradual
addition of bromine to cold pseudocumene results in the formation of a crystalline
monobromide (melting at 73°) ; the addition of any more reagent makes the prod-
uct liquid, and it finally becomes the solid tribromide, C5Br3(CH3)3, meliing at
224°. Sulphuric acid converts the crystalline symmetrical brom-cumene into the
liquid variety (1,2, 3,4) (Berichte, 22, 1580, 1586).

When crude pseudocumene, from coal tar, is poured into a mixture of fuming
NO3H and SO4H2 a crystalline mass is formed; it contains three Irinitro-cumenes.
Crystallized from benzene the mesitylene derivative separates first in long needles,
then follows the pseudocumene in thick prisms.

Hexahydro-pseudocumene, CgHj^.Hg, is the nononaphthene, Cgllu,
isolated from Caucasian petroleum. It boils at 135-138°. Its sp. gr. is 0.7812.
It forms pseudocumene sulphonic acid by solution in fuming sulphuric acid.
Bromine converts it into tribrora-pseudocumene [Berichte, 23, Ref. 431).

3. Hemimellithene, C5H3(CH3)3 (i, 2, 3), adjacent trimethyl benzene, is
obtained from a-isodurylic acid, C5H2(CH3)3.C02H, and boils at 168-170°. It
is contained in coal tar {Berichte, 19, 25 17), and may be synthesized by the action
of metallic sodium and methyl iodide upon brom-w-xylene.

{J>) Ethyl Toluenes, CjH^C^ p Tj . o-Ethyl Toluene,itom o-bromtoluenehy

means of ethyl bromide and sodium, boils at 160° C. The (i, 4)-compound from
parabromtoluene, boils at 161-162°, and when oxidized yields paratoluic and tere-
phthalic acids. The (i, 3)-ethyl toluene, from raetabromtoluene, boils at 150°.
It yields isophthalic acid on oxidation.

(c) Propyl Benzenes, CjHj.CjH,. Normal propyl benzene, obtained from
CgHjBr, propyl iodide or bromide and sodium, or from benzyl chloride, C5H5.
CHjCl, by the action of zinc ethide, boils at 157°; its specific gravity is 0.881 at
0°. In the cold bromine converts it into parabrom-propyl benzene, C^H^Br.
C3HJ, boiling at 220°. Normal cumic acid is obtained from this by the action of
sodium and CO2 {Berichte, 15, 698). If it be treated while hot, with bromine, we
get /Jy-dibrom-propyl-benzene, CjH5.CHBr.CHBr.CH3 {Berichte, 17, 709).
Propyl benzene yields phenyl-propionic aldehyde, C5H5.CH2.CH2.CHO, when
acted upon with chromyl chloride.

Isopropyl Benzene, C5H5.C3H,, called Cumene, is made by distilling cumic
acid with lime, and by the action of AlBrg upon a mixture of benzene with iso-
propyl bromide or normal propyl bromide. In the latter instance the normal
propyl group sustains a transposition (p. 577). Normal and isopropyl chlorides
also yield it. Its production from benzal chloride, CgHj.CHCl,, by means of
zinc methide, proves that the isopropyl group is present in it. Cumene boils at
153°; its specific gravity is 0.879 3* °°- Parabrom-cumene, CjH^Br.CgH,, yields
common cumic acid, CgH4(C3Hj).C02S, with sodium and COj. In the animal
organism normal propyl benzene is oxidized to benzoic acid, while isopropyl ben-
zene yields propyl phenol {Berichte, 17, 2551). ^

Nitric acid or the chromic acid mixture oxidizes both propyl benzenes to ben-
zoic acid.

576 ORGANIC CHEMISTRY.

4. Hydrocarbons, CjqHij: —

CeH,(CH3), C,H3{Jyg=j^ ^^^^^hJ ^^^^ChJ' C^H.^H,.
3 Isomerides. 6 Isomerldes. 3 Isomerides. 6 Isomerides. 4 Isomerides,

{a) Tetramethyl Benzenes, Q,^^{(ZVi:^^^. Symmetrical Durene (l, 2, 4, 5)
is formed from brom-pseudo cumene, CgH2Br(CH3)3, and dibromisoxylene,
C5H2Br2(CH3)2, by means of CH3I and sodium; and from toluene by CH3CI
and AICI3 (Annalen, 216, 200). It is present also in coal tar {Berichte, 18,
3034). It is crystalline, possesses a camphor-like odor, melts at 79-80° and boils
at 190°. Nitric acid oxidizes it to durylic and cumidic acids, €3112(0113)2.
(C02H)2 (the symmetrical constitution of durene is concluded from this [Berichte,
11,31). Monobrom-durene, C5HBr(CH3)4, melts at 61°, and boils at 263°-
It sustains a peculiar transposition into dibrom-durene and pentamethylbenzene,
when it is shaken with ordinary sulphuric acid [Berichte, 20, 2837). Dibrom-
durene melts at 199°; dinitrodurene, C8(N02)2(CH3)4, at 205°. Durene is but
slightly dissolved on shaking with concentrated sulphuric acid. When it is heated
to 100° it sustains a peculiar transformation with the production of hexamethyl
benzene, the sulphonic acids of prehnitol, pseudocumene and isoxylene, which can
be separated by means of their amides [Berichte, 20, 902). Penta methyl and
penta-ethyl benzene undergo similar transpositions (p. 578).

Unsymmetrical Isodurene (i, 3, 5, CH3) is obtained from brom-mesitylene
with CH3I and Na, and from mesitylene by means of CH3CI and AICI3, together
with durene [Berichte, 18, 338). It boils at 195° and does not solidify in the
cold. Dibromisodurene melts at 209°, dinitroisodurene at 156°. The oxidation
of isodurene with nitric acid yields three isodurylic acids, C3H2(CH3)3.C02H
[Berichte, 15, 1853), and at last mellophanic acid.

Adjacent tetramethyl benzene, called Prehnitol (i, 2, 3, 4), is produced by the
action of methyl iodide and metallic sodium upon brompseudocumene and dibrom-
metaxylene [Berichte, 21, 2821), and on warming durene with concentrated sul-
phuric acid (see above). It is separated from its sulpho-acid by heating with hydro-
chloric acid [Berichte, 21, 904). It is a liquid, boiling at 204°. It can only be
soldified by a freezing mixture ; it then melts at — 4° C. Its oxidation by nitric
acid produces prehnitylic acid, CgH2(CH3)3.C02H [Berichte, 19, 1214) and
phrenitic acid, 05112(00211)4.

The tetramethyl benzene [Berichte, ig, 1SS3), derived from brompseudocumene,
is probably identical with prehnitol. , ,--,„ ■,

[b) Symmetrical Ethyldimethyl Benzene, C3H3 \ J^ ^''^ (i, 3, 5), is pro-
duced (simultaneously with methyl diethyl benzene) by distilling a mixture of di-
methyl ketone and methyl ethyl ketone with sulphuric acid (p. 566). It boils at
185° and is converted into mesitylenic and uvitic acids by nitric acid. Methyl-

{OTT
ir Vi \ ('' 3' 5)' which is formed at the same time.

Two isomeric Ethyldimethyl Benzenes (Laurenes) are obtained by heating
camphor with ZnOlj or iodine. They boil at 183-190° (see Berichte, 23, 983,

2349)-

[c) Diethyl Benzenes, 03H'4(02H5)2. o-Diethyl Benzene, from o-dichlor-
benzene and ethyl bromide, boils at 184°. >w-Diethyl Benzene is*(with the para)
obtained by the action of AIOI3 upon benzene and ethylbromide. It boils at 182°,
and when oxidized with nitric acid yields ffz-ethylbenzoic acid and isophthalic
acid. /-Diethyl Benzene, from /-bromethyl benzene and /-dibrombenzene,
boils at l8l°- It yields.^-ethylbenzoic acid and terephthalic acid.

PARA-CYMENE. 577

{d) Methylpropyl Benzenes, C^H^ i r h • Those of the six possible

isomerides, having the normal propyl group, are designated cymenes and those
with the isopropyl group, isocymenes.

Orthocymene (l, 2) is formed from orthobromtoluene and propyl iodide, by
the action of sodium, and boils at 181-182°.

Metacymene (i, 3) is formed from metabromtoluene and propyl iodide, and
boils at 176-177°. Metaisocymene (l, 3) occurs in resin and is formed from
toluene and isopropyl iodide in the presence of AICI3. It boils at 171-175° and
is oxidized to isophthalic acid by chromic acid. Consult Berichte, 16, 2748, and
Annalen, 235, 275, for the sulphonic acids.

f CH
Para-cymene, CsHi-jpTT (i, 4) methyl normal propyl

benzene. This is usually called cymene and occurs in Roman
caraway oil (from Cuminum cyminuni), together with cumic alde-
hyde, and in other ethereal oils. It is produced on heating thy-
mol and carvacrol,

CeH3(OH).(CH3).C3H„

with P2S5, or with PCI5 and sodium amalgam; also by heating
camphor, CioHjsO, and some of its isomerides with E^Ss (along with
meta-isocymene, Berichte, 16, 791 and 2259), or with P^OsCin pure
state). When camphor is heated with ZnClj, it gives rise to a series
of benzene homologues, but, as it seems, no cymene, Berichte, 16,
624 and 2555). Cymene is obtained from turpentine oil and other
terpenes, CioHie, by the withdrawal of two hydrogen atoms. This
is effected by heating with SO4H2 or, better, with iodine, or by the
action of alkalies or aniline upon the dibromide, CioHuBrj. The
production of cymene on boiling cumic alcohol, C6H4(C3H,).
CH2.OH (having the isopropyl group), with zinc dust is especially
interesting. A transformation of the isopropyl group takes place.
Cymene may be synthetically prepared from parabrom-toluene,
C6H4Br.CH3, by means of normal propyl iodide and sodium.

Preparation. — ^Take a mixture of equal parts of camphor and P^Oj and heat
until the reaction ceases. The cymene produced is poured off, again boiled with
a little P2O5 and then distilled over sodium {Annalen, 172, 307). Or, shake
Roman caraway-oil with a concentrated sodium bisulphite solution, which also dis-
solves the cumic aldehyde contained in the oil. The oil is separated and then
fractionated.

Cymene is a pleasantly-smelling liquid, that boils at 175-176°;
its specific gravity at 0° is 0.8722. It exhibits a characteristic
absorption spectrum. It dissolves in concentrated sulphuric acid on
warming, and forms a sulphonic acid. The characteristic barium
salt, (CioHi3S03)2Ba -1- 3H2O, crystallizes in shining leaflets.

Dilute nitric acid or the chromic acid mixture oxidizes cymene to paratoluic
acid, C5H4(CH3).COjH, and terephthalic acid ; whereas in the animal cSrganism

S78 ORGANIC CHKMISTRY.

or upon shaking with caustic soda and air, it is, strange to say, converted into cu-
mic acid, €5114(0311, ).C02H (with theisopropyl group). The propyl group is con-
verted into the isopropyl group. Similarly, the same oxy-propyl-sulpho-benzoic acid ,

CsH3(C5Hg. OH) -j en tr. as that obtained from para-isocymene sulphonic acid,

is produced by the action of MnO^K upon cymene sulphonic acid. The latter
contains the normal propyl group, which was changed to the isopropyl group, then
further oxidized to oxy-isopropyl, (CH3)2.C(OH). Nitrocymene and nitroiso-

cymene, C,H3(N02)v r tI > yield the same nitro-oxy-isopropyl benzoic acid,
\C3ri5,

C5H3(N02)/^°^^Qjj {BeHchte, 21, 2231).

On the other hand, ethyl propyl benzene, isopropyl-propyl benzene, acetopropyl

benzene, C«H.(' „ ^ ^[Berichte, 21, 2224), and allied compounds are oxid-

ized to normal cumic acid, C ^^ ^{C ^H,,\CO 2^, and the propyl group remains
undisturbed. In oxidations of this character, the rearrangement of the propyl to
the isopropyl group takes place, if the second group oxidized is methyl, but not
when ethyl, propyl and acetyl are oxidized (see Fileti, Berichte, 20, Ref. 168 ;
Widmann, .5?>-!Vi/f, 22, 2280 ; 23,3081).

When concentrated nitric acid acts upon cymene, the product is not nitrocymene,
but/-tolylmethylketone {Berichte, 19, 558; 20, Ref. 373).

Para-isocymene (1,4) could not be made from parabrom-toluene and iso-
propyl iodide, but may be prepared from parabrom-cumene, CjH^Br.CjH,, by
means of methyl iodide and sodium. It resembles paracymene in odor and boils at
171-172° ; its specific gravity is 0.870 at 0°.

(if) Butyl Benzenes, CgH^.C^Hg, Normal butyl benzene boils at 180°.
Isobutyl benzene at 167°- They are obtained from brom-benzene by means of the
butyl bromides, and from benzyl chloride, C3H3.CH2CI, by propyl and isopropyl
iodides. When benzene is quickly heated to 300° with isobutyl alcohol isobutyl
benzene is formed {Berichte, 15, 1425). The secondary butyl benzene, C5H5.CH
(CHjjCjHj, is formed from /3-bromethyl benzene (p. 586) by means of zinc
ethyl. It boils at 171°. The three butyl benzenes yield benzoic acid when they
are oxidized.

Tertiary Butyl Benzene, CjHj.C(CH3)3, trimethyl phenyl methane, may be
obtained from benzene by the action of isobutyl chloride and AICI3 upon it. It
boils at 1 68°. Bromine does not attack it even when exposed to sunlight. This
behavior distinguishes it from its three isomerides {Berichte, 23, 2412).

The following higher benzene homologues may be mentioned : —
Pentamethyl Benzene, CgH(CH3)5, is produced together with hexamethyl
benzene when AICI3 and methyl chloride act upon benzene, toluene, xylene, mesi-
tylene, etc. {Berichte, 20, 896). It is crystalline, melts at 51.5° and boils at 231°
Concentrated sulphuric acid dissolves it, and it then undergoes a change similar
to that of durene (p. 576); hexamethyl benzene and prehnitol sulphonic acid are
produced : —

2CeH(CH3)3 + SO.H^ = Ce(CH3)3 + C3H(CH3),.S03H -f H^O.

Chlorsulphonic acid, SO3CIH, converts it into the sulphone and the sulpho-acid of
pentamethyl benzene {Berichte] 20, 869). The remaining H-atojn can be readily
substituted by acetyl, carboxyl, etc. {Berichte, 22, 1218).

Isoatnyl Benzene, CsHj.CjH,,, boils at 193°. Amyl Benzene, CjHs.CjHjj,
from benzyl bromide, CjHj.CHjBr, and butyl bromide, boils at 201°.

HALOGEN DERIVATIVES. 579

Hexamethyl Benzene, C6(CH3)8= Ci^His, is formed, together
with the preceding {Berichte, 20, 896), by the polymerization of
crotonylene, CHa.CiC.CHs, on shaking with sulphuric acid (p. 566),
and by heating xylidene hydrochloride and methyl alcohol to 300°
(p. 568). It crystallizes from alcohol in plates or prisms, melts at
169°, and boils at 264°. It does not dissolve in sulphuric acid, as
it is incapable of forming a sulpho-acid. Potassium permanganate
oxidizes it to benzene hexacarboxylic acid, C8(C02H)5 (mellitic
acid).

Dipropyl Benzene, C8H^{C3H,)2 (i, 4), is formed from paradibrom-benzene
and propyl iodide, and boils at 219°. When oxidized with dilute nitric acid it
forms parapropyl benzoic acid, CsH4(C3H,).C02H (normal cumic acid).
Propyl-isopropyl Benzene, C6H^(C3H,)C3H,, derived from cumyl chloride,

*--6^4\ rRfCH ■> > ^"d ™^^ ethyl, boils at 212°, and also yields parapropyl
benzoic acid when oxidized with nitric acid.

Symmetrical Triethyl Benzene, CgH3(CjH5)3 (i, 3, 5), is made by distilling
ethyl-methyl ketone, C2H5.CO.CH3, with sulphuric acid (p. 566) and by the
action of ethylene and AICI3 upon benzene. It boils at 218°, and yields trimesic
acid with chromic acid.

w-Tetraethyl Benzene, C^ll^{C2'H.^)^ = Cj^H^^ (l, 2, 3, 4), is obtained
from benzene, CjHjBr, and AlCl,, and from penta-ethylbenzene by the action of
sulphuric acid. It is liquid and boils at 251°. It yields phrenitic acid, C^Hj
(COjH)^, when oxidized with MnOiK.

Normal Octyl Benzene, CjHj.CgHiy = Cj^Hj^, from brom-benzene and
normal octylchloride, boils at 262-264°, and solidifies in the cold. It yields ben-
zoic acid when oxidized {Berichte, ig, 2717).

Pentaethyl Benzene, CgH(C2H5)5, from benzene by the action of ethyl
bromide and AICI3, is a thick oil, boiUng at 277°. Chlorsulphonic acid converts
it into a sulpho-acid. When it is shaken with concentrated sulphuric acid it yields
tetra- and hexa-ethyl benzene {Berichte, 21, 2814).

Hexaethyl Benzene, Cg(C2H5)8 = CuHj^, crystallizes in large prisms,
melting at 1 26°, and boils at 305°.

Hexadecyl Benzene, CgHj.CjjHgi, and Octodecyl Benzene, CgH^.
C, jHj J, are obtained by the action of hexadecyl iodide and octodecyl iodide upon
iodobenzene. The first melts at 27°, and boils at 230° under a pressure of 15
mm.; the second melts at 36° and boils at 249°, under a pressure of 15 mm.
{Berichte, 21, 3181).

HALOGEN DERIVATIVES.

The hydrocarbons of the aromatic series are more rapidly substi-
tuted by chlorine and bromine than the paraiRns. In the benzene
homologues the substitution occurs both in the residue and in the
side groups :; —

CeH3Cl2.CH3, CsH.Cl.CH^Cl, C.H^.CHCl^.

In the nucleus the halogen atoms are very firmly attached, and are
not displaced by the action of KOH, silver oxide, ammonia, or

580 ORGANIC CHEMISTRY.

sodium sulphite. The readiness with which they react with piperi-
dine is interesting and remarkable {Berichfe, 21, 2279). If nitro-
groups enter, then the halogens become more reactive. The halo-
gen atoms in the side-chains behave as in the fatty bodies.

The transpositions, that various chlor- and brom-derivatives of
the alkylbenzenes sustain when shaken with sulphuric acid, are
worthy of note {Berichte, 23, 2318).

The methods of forming the halogen products are perfectly
analogous to those in the fatty-series (p. 90).

(i) Bromine and chlorine manifest an interesting deportment
in their substitution. In the cold and in presence of iodine,
M0CI5 01; FcjCle (also when heated), they act on the nucleus only j
from toluene, (C6H6.CH3),CeH4Cl.CH3,C6H4Br.CH3, and other
products are obtained (^Berichte, 13, 1216). On the other hand,
on conducting chlorine or bromine vapors into boiling toluene
(and its homologues), the side-chains are almost exclusively substi-
tuted ; CeHs. CH2CI, CsHj. CHCI2 and CsHj. CCI3 are obtained. Act-
ing in the warm and cold alternately (or in presence of iodine), we
can substitute hydrogen atoms in the side-chains or in the nucleus
(Beilstein).

It is only in exceptional cases that iodine acts substitutingly
(p. 91).

Sunlight has the same eflfect as heat. Chlorine and bromine then, in nearly all in-
stances, act upon the side-chains (Schramm, ^^r;V^^«, 18, 608; 19, 214). Ferric
chloride is also a carrier of bromine and chlorine (p. 91) ; it is ajso applicable in
iodation (Annalen, 231, 195). Nitrobenzene, CgH5N02, may be substituted in
this way.

When the homologous benzenes are heated in sealed tubes, together with PCI5,
the side-chains are alone substituted {Berichte, ig, Ref. 24).

The action of chlorine and bromine slowly diminishes with the number of halogen
atoms already introduced. For further chlorination, the substances must be heated
with phosphorus chloride, molybdenum chloride, or iodine chloride [Berichie, 8,
1296). In such energetic chlorinations the side-chains of the benzene homologues
are at last severed. Thus, from toluene, xylene, cumene, cymene, etc., we finally
obtain perchlorbenzene, CgClg, while the side groups disappear as CCI4. Naph-
thalene, anthracene, phenanthrene, and many other benzene compounds behave
similarly [Benchte, 16, 2869). A like decomposition occurs on heating with bro-
mine containing iodine ; CgBfj and CBr^ are formed in this instance. Bromine
reacts similarly, but more readily, in the presence of Al^Br^ (Berichte, 16, 2891) ;
from cymene we get C^Brs.CHj and isopropyl iodide.

(2) Action of the phosphorus haloids upon the phenols and aro-
matic • alcohols (p. 558); here, both the hydroxyls in the nucleus
and in the side-chains are replaced by halogens (p. 91) : —

CeH, { ^ -f PCI5 = _C,H, { ^^ -i- POCI3 -K HCl,
C5H5.CHj.OH -t- PCI5 = CgH^.CHjCl -I- POCI3 4- HCI.

BENZENE DERIVATIVES. 581

(3) An important method, and one that is only applicable in the
case of benzene derivatives, consists in the transformation of the
diazo-compounds (see these). The diazo-group can be replaced by
chlorine, bromine and iodine by various reactions. This behavior
serves to substitute the halogens for nitro- and amido-groups through
the agency of diazo-compounds : —

CeH5.NO, yields CeH^.NH,, C^H^.N^X and CeHsfCl, Br, I).
Nitro- Amido- Diazo- Benzene Haloid,

benzene. benzene. benzene.

Halogen products can be obtained from substituted amido-com-
pounds by introducing hydrogen for the amido-group through the
diazo-derivative : —

CeHjBrj.NHj yields C^H^Br,.

(4) Decomposition of substituted acids by heating them with
lime (p. 570):—

C H^Cl.CO.H = CeH.CI + COj.

Chlorbenzoic Acid. Chlorbenzene.

Additive products are obtained by letting an excess of chlorine
or bromine act upon benzene or the chlor-benzenes, in the sunlight
(p. 567):—

CeHjCLClj CsHjCLClj CsHjCl.Cle, etc.

Hexachlorbenzene, CgHjCljjis also formed by conducting chlorine into boiling
benzene; substitution products are produced at the same time. The additive
products are solids, and do not volatilize without decomposition. When distilled or
heated with alkalies, half of the added chlorine (or bromine) breaks off as hydro-
gen chloride (or bromide) : —

CeH.ci.ci^ = c.nfih + 2HC1.

Protracted action of sodium amalgam upon the alcoholic solutions of the halo-
gens brings about the substitution of hydrogen for the halogens. Heating with
hydriodic acid and phosphorus effects the same result.

BENZENE DERIVATIVES.

Monochlor-beilzene, CgHjCl, phenyl chloride (the group C5H5 is called
phenyl), is obtained from benzene, and from phenol, CgHj.OH, by the action of
PCI5 upon the latter. It boils at 132° and solidifies at — 40°; its sp. gr. at 0° is
1. 128.

Dichlor-benzenes, CgH^Cl,. In the chlorination of benzene the products
are chiefly solid para- and a little liquid ortho-dichlor-benzene.

Paradichlor-benzene (l, 4) forms monoclinic needles, melts at 56°, and boils
at 173°. It is obtained also by the action of PCI5 on para-nitraniline, para-
chlorphenol and para-phenol-sulphonic acid. It forms a mononitro-product,
CeHjCl^.NO^ (I, 4, NO,), melting at 55°.

582 ORGANIC CHEMISTRY.

Metadichlor-bensene (i, 3), from metachlor-aniline, /3-dichlor-aniline, CgH^CIj.
NH2, and common dinitro-benzene, is a liquid, and boils at 172°. Its mononitro-
derivative melts at 32° (i, 3, 4 — NOj in 4).

Orthodichlor-benzene (l, 2), from benzene and orthochlor-phenol, is a liquid,
and boils at 179° ; its nitro-derivative melts at 49° (i, 2, 4 — NOj in 4).

Trichlor-benzenes, CgHjClg.

Ordinary trichlor-benzene (i, 2, 4) is produced in the chlorination of benzene,
or the three dichlor-benzenes, and is also obtained from benzene hexachloride,
and a-dichlor-phenol. It melts at 17°, and boils at 213°. Its nitro-compound
(I, 2, 4, S — NOj in 5) melts at 58°.

Symmetrical Trichlor-benzene (i, 3> S) is obtained from ordinary trichlor-
aniUne and from C^HjCLCl^. Long needles, melting at 63.5°, and boiling at
208°.

The adjacent trichlor-benzene (i, 2, 3) is formed from trichlor-aniline (i, 2,
3, 4). It consists of plates which dissolve with difficulty in alcohol, melt at 54°,
and boil at 218° (Annalen, 192, 228).

Tetrachlor-benzeries, C^HjCl^.

Ordinary (symmetrical) tetrachlqr-benzene (l, 2, 4,5) is produced in the chlori-
nation of benzene, or is. obtained from the nitro-derivative of common trichlor-
benzene (melting at 58°). It melts at 138°, and boils at 243-246°- Boiled with
nitric acid it yields chloranil, CgCl^Oj (O^ ^ i, 4). The unsymmetrical tetra-
chloride (l, 3, 4, S) =: (l, 2, 4, 6) is formed from ordinary trichlor-aniline, and
consists of needles, melting at 51°, and boiling at 246°.

The adjacent tetrachlorbenzene (l, 2, 3,4) is formed from adjacent trichlor-
aniline (from metachlor-aniline), and consists of long needles, melts at 46°, and
boils at 254° [Annalen, 192, 236).

Pentachlor-benzene, CgHCl,;, can only exist in one modification. It is pro-
duced by chlorination ; forms needles, which melt at 86°, and boil at 276°.

Hexachlor-benzene, CgClg, is produced in the chlorination of benzene and
other compounds (p. 580) in the presence of SbClj or ICI3, and when CHCI3 or
C2CI4 are conducted through tubes heated to redness. It melts at 226°, and boils
at 332°. It forms perchlorphenol when heated to 250° with caustic potash {Be-
richte, 18, 335).

Benzene Hexachloride, C5H5CI5, obtained by the action of chlorine upon
benaene in sunlight, or upon boiling benzene, melts at i57°- When it is distilled,
it decomposes into C5H3CI3 -j- 3HCI. See Berichte, 18, Ref 149, for an isomeric
hexachloride.

Monobrom-benzene, CgHjBr, from benzene and phenol, boils at 155° ; its
specific gravity at olis 1.517.

Dibrom-benzenes, CgH^Brj. When bromine acts upon benzene (on heat-
ing) [Berichte, 10, 1354), it is chiefly the para- and little of theortho- that results.

p-Dibrom-benzene (i, 4), from benzene, parabrom-phenol and para-bromaniline,
melts at 89°, and boils at 2 1 8°. Its mononitro-derivative (i, 4,N02) melts at 85°.
m-Dibrom-benzsne (l, 3), firom ordinary dinitro-benzene and dibrom-aniline, does
not solidify at — 20°, and boils at 219°. It yields two mononitro-products, one of
which melts at 61° (l, 3, 4 — NOj in 4) (chief product), the other (i, 3, 2 — NOj
in 2), at 82.5°. o-Dibrom-benzene (l, 2), from orthonitraniline and orthonitro-
brom-benzene, becomes solid below 0°, melts at — 1°, and boils at 224°.' Its nitro-
product (i, 2, 4 — NO2 in 4) melts at 58.6°.

Tribrom-benzenes, CgHjBrj. Korner was the first to make a comprehen-
sive investigation of these derivatives with respect to their relations to the three
dibrom-benzenes, and to examine into their structure (p. 5^^)-

DERIVATIVES OF TOLUENE. 583

Ordinary unsymmetrical tribrom-benzene (i, 3, 4) is obtained directly from
benzene by the action of bromine. It results from all three dibrom-benzenes,
hence (i, 3, 4) ; also from CgHgBrj, from common dibrom-phenol and from ordi-
nary dibrom-aniline. It melts at 44°, and boils at 275°- Symmetrical tribrom-
benzene (I, 3, 5), from tribromaniline, melts at 119.5°, ^n<i \id\\s about 278?.

The third adjacent tribrom-benzene (i, 2, 3) is formed like the corresponding
trichlor-benzene, and melts at 87°.

Tetrabrombenzenes, CgH^Br^. The common variety results from the treat-
ment of benzene and nitro-benzene with bromine. It melts at 1 75°- The unsym-
metrical vaxitiy (i, 3, 5,Br)is obtained from ordinary tribromaniline and ordinary
tribromphenol. It melts at 97-99°, and boils near 329°.

Pentabrombenzene, CgHBrj, the only possible modification, is obtained by
acting on benzene with bromine. It melts near 240°.

Hexabrombenzene, CgBr^, is formed by heating benzene (toluene, etc., p. 580)
and bromine to 300-400° ; or by heating CBr^ to 300°. It consists of needles,
almost insoluble in alcohol and ether ; they melt above 310°.

Benzene Hexabromide, CgHgBrgjis produced when bromine acts on ben-
zene in sunlight. It is a crystalline compound and decomposes, when heated,
into unsymmetrical tiibrombenzene and HBr.

lodo-benzene, C5H5I, is formed on heating benzene with iodine and iodic
acid ^o 200° ; by the action of phosphorus iodide upon phenol, and from aniline
through the diazo-compound. It is a colorless liquid, boiling at 185°; its sp. gr.
equals 1.69.

Di-iodo-benzenes, CgH^Ij : (i, 4) melts at 129° and boils near 280°; (l, 3)
melts at 40.5° and boils at 282°; both crystallize in leaflets, (i, 2) crystallizes
on cooling, melts at 27°, and boils at 286° (Berichte, 21, Ref. 349).

Tri-iodo-benzene, CgHjIj, melts at 76° and sublimes readily.

Fluorbenzene, C5H5FI, has been obtained from potassium fluorbenzoate. A
liquid with an odor like that of benzene, and boiling at 85° [Berichte, 17, Ref.
109). p-Fluortoluene, CjH^Fl.CHj, obtained in an analogous manner, has an
odor like that of bitter almond oil, and boils at 114°. When it oxidizes it forms
/-fluorbenzoic acid.

These fluorbenzenes are also formed in the action of concentrated hydrofluoric
acid upon the benzene diazoamido-compounds with fatty residues (Berichte, 19,
Ref. 753; 21, Ref. 96). Fluornitrobenzene , C5H^(N02)F1 (i, 4), melts at
24° C. and boils at 205° C. p-Difluorbemene, CgH^Fljj, boils at 88°.

DERIVATIVES OF TOLUEN^i.

Chlortoluenes, CeHiCLCHj. Para- and ortho-derivatives are
produced in an almost equal amount when toluene is treated with
chlorine and bromine (in the cold or in the presence of iodine
(p. 580). The former is a solid and boils somewhat higher than
the ortho-compounds. The haloid toluenes may be obtained pure
from the amido-toluenes, by replacing the NHj-group by halogens ;
this is accomplished through the diazo-compounds. Thus CeH^
(NHj).CHs yields CsHiX.CHs. When heated with a chromic
acid mixture (see aromatic acids) the para- and meta-derivatives
(by the conversion of the CHj-group into CO2H) are oxidized to
the corresponding substituted benzoic acids, whereas the ortho-

584 ORGANIC CHEMISTRY.

derivatives are attacked with difficulty and completely destroyed.
When boiled with dilute nitric acid, with Mn04K, or ferricyanide
of potassium, all three isomerides (even the ortho) are oxidized to
acids.

Parachlortoluene, CjH^Cl.CHj (i, 4), solidifies at 0°, melts at 6.5° and boils
at 160°. It yields parachlorbenzoic acid when oxidized with chromic acid or
nitric acid. Orthochlortoluene (l, 2), from toluene and orthotoluidine, is liquid,
and boils at 156°; chromic acid completely decomposes it. Metachlortoluene
(i, 3) has been prepared from chlorparatoluidine, CjHjCl(NH2).CH3, by re-
placement of NHj by hydrogen. It boils at 150° and yields metachlorbenzoic
acid. See Berichte, 19, 2440 for nitrochlortoluenes.

Benzyl Chloride, CeHs.CHjCl, a-chlortoluene is obtained by
the chlorination of boiling toluene (p. 580), and from benzyl alco-
hol, CeHs-CH^. OH. It boils at 176°. The chlorine atom is
readily exchanged. It passes into benzyl alcohol when boiled with
water (30 parts). Heated with water and lead nitrate it yields
benzaldehyde, and by oxidation benzoic acid.

When benzyl chloride is heated to 200° with water, tbe chloride, C14HJ3CI,
is produced, and by the distillation of this product, benzyl toluene, CgH^.CH^.
CjH^.CHg, anthracene, Cj^H^, and other bodies are formed.

In the nitration of CeHj-CH^Cl, C5H5.CHCI2 and C5H5.CCI3, the products
are predominantly /a?-a-««Vro-derivatives with some of the ortho. Further oxida-
tion transforms these into nitro-benzoic acids [Berichte, 17, 385 and Annalen,
224, loo). From CgHs-CHO, CjHj.CO.CHg, CgHj.CO^H and CjHj.CN, we
obtain meta-products principally. 0- and /-Nitrobenzyl chlorides are also obtained
by the chlorination, at a boiling temperature, of 0- and/-nitrotoluenes; the o- and
?M-chlorides are more easily produced by the action of PCI5 upon 0- and »«-nitro-
benzyl alcohol {Berichte, 18, 2402).

«-Nitrobenzyl chloride, C5H4(N02).CH2C1, melts at 49°; the meta- at 45-47°;
the para at 73° C. Pyrogallol reduces the latter to nitrotoluene. For its deriva-
tives see Berichte, 23, 337. ^

Dichlortoluenes, CjHgClj:—

CeHjCl^.CHj CeH^Cl.CH^Cl CeHj.CHCV

Dichlortoluenes. Chlorbenzyl Chlorides. Benzal Chloride.

The first compound -must have six modifications ; the six corresponding dibrom-
toluenes have all been prepared. There must be three isomerides of the second,
and of the third compound only one modification is possible.

Benzal Chloride, CjHj.CHCl, (Benzylene chloride, Chlorobenzene), is
- formed in the chlorination of boiling toluene and from oil of bitter-almonds,
CeHj.CHO, by means of PCI5. It is a liquid boiling at 206°, and has a sp. gr.
1.295 at 16°. It changes to oil of bitter-almonds when exposed to a temperature
of 120° in the presence of water. Satisfactory nitro-products have not been
obtained by the nitration of benzalchloride or by conducting chlorine into
/-nitrotoluene {Berichte, 18, 996). p-Nitrobenzal chloride, C5H4(NO,).CHClj,
has been prepared by the action of PCI5 upon /-nitrobenzaldehyde. It melts at 46°.

On heating /-nitrotoluene with bromine to \2.o-\\o° , p-Nitrobenzyl bromide,
C6H4(NO.J.CH2Br,and p-Nitrobenzal bromide, Q^Yi.^{^O^.CYi-&x^ are readily
formed. The first melts at 100°, and the second at 82° {Annalen, 185, 268).

DERIVATIVES OF TOLUENE. 585

Trichlortoluenes, CjHjClj :—
C5HJCI3.CH3 CjHjOj.CHjCl CsH.Cl.CHClj CjHj.CCIj.

6 Isomerides. 6 Isomerides. 3 Isomerides. 1 Modification.

Two tricUorine derivatives, a- and /J- (l, 2, 4, 5 — CH3 in I and i, 2, 3, 4),
CgH^Clj.CHj, are formed in chlorinating toluene ; the a- melts at 82° and boils at
230°; the /3- melts at 41° and boils at 232° {Berichte, 18, 421). In accordance
with its constitution diamid-a-trichlortoluene is oxidized to trichlortoluquinone.

Benzotrichloride, C5H5.CCI3, prepared from benzoyl chloride, C5H5.COCI, by-
action of PCI5, is a liquid, and boils at 213°. It yields benzoic acid when heated
to 100° with water.

Pentachlortoluene, C5CI5.CH3, melts at 218° and boils at 301°. Further
chlorination leads to the substitution of the methyl group, which finally is broken
off and hexachlorbenzene, C3CI5 (p. 580), formed.

Monobromtoluenes, CgH^Br.CHj.

Parabromtoluene (1,4), from toluene and paratoluidine, melts at 28.5° and boils
at 185°; it yields parabrombenzoic acid. , ^tt

Metabromtoluene (l, 3) is formed by acting on, CgH^ \ Nh't H O ^"^^'P^ra-

toluidine, with bromine, and replacing the amido-group by hydrogen ; and in a
similar manner from acetorthotoluidine. It boils at 184°, and yields metabrom-
benzoic acid. Orthobromtoluene (l, 2), obtained with the para- on treating
toluene with bromine, and also from ortho-toluidine, boils at 182-183° 5 ''s sp. gr.
at 20° is 1 .40. A chromic acid mixture gradually destroys it ; dilute nitric acid
oxidizes it to orthobrombenzoic acid.

Benzyl Bromide, CgHj.CHjBr, is prepared by the action of bromine upon
boiling toluene, and by the action of HBr upon benzyl alcohol. It is a liquid,
which provokes tears and boils at 210° ; its specific gravity = 1.438 at 22°.

pibromtoluenes, CgHjBrj.CHg. The six possible isomerides have been
prepared in various ways {Berichte, 13, 970).

Benzal Bromide, CgHj.CHBrj, from benzaldehyde, decomposes upon distilla-
tion.

o-Brombenzyl Bromide, CgH^Br.CHjBr, from ortho-bromtoluene, melts at
30°, and with sodium forms anthracene and phenanthrene. Chromic acid does not
oxidize it. p-Brombenzyl Bromide, from /-bromtoluene, melts at 61°.

lodo-toluenes, C5H^I.CH3.

Paraiodotoluene (l, 4), from paratoluidine, crystallizes in shining laminae, melts
at 35° and boils at 211°. Chromic acid converts it into paraiodobenzoic acid.
M-etaiodotoluene (I, 3), from liquid metatoluidine, is a liquid boiling at 207°,
and when oxidized by chromic acid yields metaiodobenzoic acid. Orthoiodo-
toluene (i, 2), from orthotoluidine, is liquid, and boils at 205°. When oxidized
with dilute nitric acid it becomes orthoiodobenzoic acid.

Benzyl Iodide, CjH^.CHjI, is obtained from benzyl chloride by the action of
hydriodic acid at the ordinary temperature. It melts at 24° and decomposes when
distilled.

Ethyl Benzene Derivatives, CjH5.CH2.CH3.

The replacement of the hydrogen in the ethyl group gives rise to two isomeric
mono- and three isomeric di-derivatives : —

C5H5.CH2.CH2CI CsHj.CHBr.CHj (

a-Chlorethyl Benzene. g Bromethyl Benzene.

49

586 ORGANIC CHEMISTRY.

The (2-derivatives have also been called u-derivatives, the /3- the a-derivatives.

a-Chlorethyl Benzene is formed in the chlorinatiori of hot ethyl benzene. It
is an oil boiling at 200-204° C, when it decomposes into hydrochloric acid and
styrene. Potassiran cyanide converts it into a cyanide and then hydrocinnamic
acid. /3-Chlorethyl Benzene, obtained from phenyl methyl carbinol, C^H^
CH(0H).CH3, through the action of HCl, boils at 194° C.

a-Bromethyl Benzene, from styrene by the action of HBr, decomposes into
the latter and styrene on warming. The ^-product is produced when ethyl ben- .
zene is brominated at a boiling temperature or in sunlight {Berichte, 18, 35l\ and
also results from the action of HBr upon phenyl methyl carbinol (see above). It
does not react either with KCN or with COj and sodium.

a-Dichlorethyl Benzene, CgHj.CHj.CHClj, from phenyl-acetaldehyde and
PCI 5, is an oil with penetrating odor. Alcoholic potash converts it into a-chlor-
styrene {Berichte, 18, 982). |8-Dichlorethyl Benzene, C8H5CCI2.CH3, is
formed from acetophenone, C5H5.CO.CH3, and PCI5. a^S-Dichlorethyl Ben-
zene, C5H5.CHCI.CH2CI, styrene chloride, from styrene by the absorption of
2CI, yields a-chlorstyrene with alcoholic potash.

a/3-Dibromethyl Benzene, CjHj.CHBr.CHjBrjStyrene bromide, is produced
by the action of bromine upon styrene, and by the bromination of ethyl benzene in
diffused light (Berichte, 18, 3S4). It is a solid and melts at 74° C. With alco-
holic potash it yields /3-bromstyrene. ^-Dibromethyl Benzene, CjHj.CBrj.CHj,
formed by the bromination of ethyl benzene in sunlight, is a liquid.

The halogen derivatives of the higher benzenes are described in connection
with these.

NITRO-DERIVATIVES.

All benzene derivatives readily pass into nitro-products (p. 105)
through the action of nitric acid, the benzene nucleus (not the side-
chains) being substituted : —

C.H^.CHg -f NO3H = CeH,(N02).CH3 -f H^O.

The substance to be nitrated is gradually added to concentrated
or fuming nitric acid, when it will dissolve with evolution of brown
vapors. When this does not occur heat should be applied. On
pouring the solution into water the nitro-products, not soluble in
water, are precipitated.

A mixture of nitric acid (i part) and sulphuric acid (2 parts) acts more energet-
ically, as the second acid combines with any water that may be formed in the
reaction.

Di- and tri-nitro-compounds are the chief products.

The nitration is considerably moderated by previously dissolving the substance
in glacial acetic acid. The more alkyl groups there are in a benzene hydrocarbon,
the more readily will it be nitrated. Nitric acid of sp. gr. 1.5 very frequently reacts
more energetically than the acid of 1.535 sp. gr., because the latter contains more
nitrogen dioxide (Berichte, 21, Ref. 51).

Nitro-derivatives of substituted hydrocarbons are obtained: (l) by nitration of

DERIVATIVES OF BENZENE. 587

the halogen derivatives, while in the inverse action of chlorine and bromine upon
nitro-derivatives in the heat the nitro-group is generally eliminated ; (2) by the
action of PCI5 and PBrj upon nitro-phenols, e. g., CeH4(N02).OH, when the
hydroxyl group is replaced by halogens ; (3) from nitro-amido-compounds, the
amido-group being exchanged for halogens through the agency of the diazo-com-
pounds; (4) by the action of potassium nitrite and copper upon diazo-salts; (5)
by decomposition of nitro-acids when heated with lime (p. S7o).

Various reducing agents convert the nitro into amido-compounds
(P- 591)- Sodium amalgam or alcoholic potash produces azo-com-
pounds. The nitro-derivatives generally possess a faint yellow
color; ammonia deepens the latter. The mono-nitro-benzenes
usually boil undecomposed ; the di-derivatives are not volatile.

DERIVATIVES OF BENZENE.

Nitro-benzene, CeHs-NOj, is obtained by dissolving benzene
in a mixture of common nitric and sulphuric acids. It is a bright
yellow liquid, possessing an odor resembling that of oil of bitter
almonds (artificial almond o'il, oil of mirbane), and a specific
gravity at o° of 1.20. It becomes crystalline at + 3° and boils at
205°.

Dinitro-benzenes, C6H4(N02)2. The three dinitro-benzenes
are produced, if in the nitration with fuming nitric acid, the mix-
ture be boiled a short time. On crystallizing from alcohol, the
meta-compound, formed in greatest quantity, separates first, whereas
the ortho-and para-dinitro-derivatives remain in solution {Berichte,
7, 1372). For the production of (7-dinitro-benzene, see Berichte 17,
Ref. 20.

The ortho-compound (like other ortho-dinitro-benzenes) exchanges an NO^-
group for OH when boiled with caustic soda, forming o-nitro-phenol, C8H,(N02).
OH. Likewise on heating orthodinitro-compounds with alcoholic ammonia (and
with anilines), we have «-nitranilines, e^.g., CjH^(N02).NH2, produced. Ferri-
cyanide of potash and caustic soda oxidize the metadinitro-benzenes to dinitro-
phenols; they unite with aniline, yielding molecular compounds;, m- and^-Dini-
trobenzenes combine, too, with benzenes, naphthalenes, etc. [Berichte, 16, 234).

Meta-dinitrobenzene ( i , 3) is obtained from common dinitrotoluene (1,2,4, CH3 in
l), and from a- and j3-dinitraniline ; it was formerly called para. It crystallizes in
long, colorless needles, sparingly soluble in cold alcohol, and melting at 89.9°. It
boils at 297°. By reduction it yields (l, 3)-nitraniUneand (i, 3) phenylene diamine
(melting at 63°). When heated with potassium ferricyanide and caustic soda, it
forms a- and /3-dinitrophenol, C5H3(N02)2.0H. w-Dinitro-benzene, heated
with alcoholic potash, has one of its nitro-groups removed with formation of
C8H3fNOa)(O.C2H5).CN, which, heated with alcohohc potash, yields dioxy-
ethyl benzonitrile, C5H3(O.C2H5)2CN. This fused with KOH, becomes dioxy-
benzoic acid. When paradinitrobenzene (not ortho) is boiled with alcoholic

588 ORGANIC CHEMISTRY.

potassium cyanide potassium nitrite is also formed (Berichte, 17, Ref. 19). Upon
digesting nitro-oxyethyl benzonitrile with potassium methylate, the nitro group is re-

placed and oxyethyl-oxymethyl-benzonitrile formed : C5Hj(CN);^q'(-.|j ^ (i, 2

6, CN in I) Berichte, 18, Ref. 148.

Paradinitrobemene (1,4) forms colorless needles, is more sparingly soluble in
alcohol, melts at 173°, and yields (1, 4)-nitraniline and (l, 4)-phenylene diamine
(melting at 140°).

Orthodinitro-benzene (i, 2), formed in very small amount in nitration, crystallizes
in plates from hot water, and melts at Il8°. It yields (i, 2)-nitraniline, and (i, 2)-
phenylenediamine (melting at 99°).

Symmetrical Trinitrobenzene, CgH3(N02)3 (l, 3, S), is produced by heat-
ing meta-dinitrobenzene with HNO3 and pyrosulphuric acid to 140° ; it crystallizes
in white laminse or needles and melts at 121-122°. It becomes trinitrophenol
(Picric Acid) when heated with ferricyanide of potassium and caustic soda. It
unites with benzenes and anilines, forming molecular compounds [Berkhie, 13,
2346). /-Dinitrobenzene forms unsymmetrical trinitrobenzene (i, 2,4) {^Be-
richte, 17, Ref. 233).

Nitro-haloid Benzenes, C5H4X(N02).

Upon nitrating chlor-, brom-, and iodo-benzene, para- and ortho-mononitro
products result; the first in larger quantity. The meta-derivatives are pre-
pared from meta-nitraniline, CgH4(N02).NH2 (from common dinitro-benzene), by
replacement of the amido group by halogens, effected by means of the diazo-com-
pounds. The para- and ortho-compounds can be similarly prepared from the
corresponding nitranilines. PCI5 also conv^ts nitro-phenols, CgH4(N02).OH,
into chlornitro- derivatives. Metachlomitro-benzene is obtained by the chlorina-
tion of nitrobenzene in the presence of iodine, or SbClj.

The isomeric mononitro-chlor-, brom-, and iodo-benzenes have the following
melting points : — •

(!,=)• (1.3). (1,4).

Cell^CKNO,} 32.5° 44.4° 83°

CsH4Br(N0j) 41.5° 56° 126°

C,HJ (NO,) 49° 33° 171°-

Meta-chlornitrobenzene occurs in two physical modifications : if rapidly cooled
after fusion, it melts at 23.7°, but in a short time reverts to the stable modification,
melting at 44.4°.

As may be seen above, the para-derivatives possess the highest
melting points, and the meta- are generally higher than the ortho.
A similar deportment is manifested by almost all di-derivatives of
benzene (p. 598). Again, the para-compounds usually dissolve
with more difficulty in alcohol. The different behavior of chlor-
and brom-nitrobenzenes with caustic potash and ammonia is very
instructive. The ortho- and para-derivatives (latter with more
difficulty than the former) yield the corresponding nitro-phenols,
C6H4.(N02).OH, when heated with aqueous or alcoholic potash in
closed tubes to 120°. In this reaction the halogens are replaced by
hydroxyl. The meta-derivatives do not react under the above con-
ditions. The ortho- and para-compounds also yield corresponding •
nitranilines, C6H4(N02).NH2, when heated to 100° with alcoholic

DERIVATIVES OF BENZENE. 589

ammonia, while the (i, 3)-chlor- and brom-nitrobenzenes do not
react (compare dinitrobenzene (p. 587) and the nitranilines).

In the nitration of the mono-haloid benzenes, as well as in the
chlorination (bromination) of benzene (p. 580) and toluene (p. 583),
the para- and ortho-compounds (i, 4) and (i, 2) are almost the
only products. So in the nitration (chlorination) of phenol,
C8H5.OH, of toluene, C6H5.CH3, and of aniline, CeHj.NHi,, the
first derivatives are only the ortho- and para-varieties. It is only
in the nitration (chlorination) of nitrobenzene, C6H5(N02), ben-
zoic acid, CeHs.COjH; benzaldehyde,, CsHj.CHO, benzonitrile,
CsHs.CN, acetophenone, CsHj.CO.CHg, and some additional com-
pounds, with negative side-chains, that the meta-derivatives predom-
inate in the presence of the ortho- and para-varieties.

Thus, from benzoic acid we get meta-nitrobenzoic acid, from
nitrobenzene meta-dinitrobenzene, C6Hi(N02)2 (i, 3). Benzene
sulphonic acid, CeHj.SOsH, yields meta-benzene disulphonic acid,
C6H4(S03H)2 (i, 3). The following groups: OH, NH^, CI and
Br, CH3 and all alkyls cause the entering, substituting group to
assume the ortho- and para-positions, and have been designated
substituents of the first class, while the groups NO^, CO2H, CN,
CO.CH3, SO3H, etc., are known as substituents of the second class
(see Lellmann, Principien der org. Synthese, p. 11). Consult
JBerichte, 23, 130 upon the influence exerted' by the atomic magni-
tude of the substituents.

By the further substitution (chlorination, nitration) of the ortho-
and para-di-derivatives (from compounds containing substituents of
the first class) the replacing groups enter the para- or ortho-posi-
tion, so that di-derivatives (i, 2) and (i, 4) yield the same tri-
derivatives (i, 2, 4). Hence, the tendency of the tri-derivatives is to
form the unsymmetrical combination (see Annalen, 192, 219). The
substitution relations are more complicated in the case of the meta-
di-derivatives (i, 3).

If an unsymmetrical tri-derivate (i, 2, 4) be further substituted,
unsymmetrical tetra-derivatives (i, 2, 4, 6) are generally produced.
Thus, from aniline, CeHj.NHj, phenol, CeHj.OH, etc., we obtain
compounds like CeH^CU-NHj and C6H2(N02)3.0H (i, 2, 4, 6— NH^
or OH in i), in which the entering groups occupy the meta-position
(2, 4, 6 ^ I, 3, 5) with reference to each other. By the elimina-
tion of the OH ■ and NH2 groups in them, we obtain symmetrical
tri-derivatives, C6H3X3 (i, 3, 5).

a-Dinitro-chlorbenzene, C5HgCI(N02)2 (l, 2, 4), is obtained from (I, 2)- and
(l, 4)-chlornitro-benzene, or from ordinary dmitrophenol, and by the direct nitra-

590 ORGANIC CHEMISTRY.

tion of C5H5CI. It melts at 53.4°. The nitro-groups in it hold the position
(i, 3) = (2, 4).

a-Dinitro-brombenzene, CgH3Br(N02)2 (i, 2, 4), is formed like the pre-
ceding and melts at 75.3°. When boiled with a soda-solution both yield ordinary
dinitrophenol, and with alcoholic ammonia a-dinitraniline (melting at 182°).

The nitration of meta-chlor and bromnitro-benzene produces the isomerides
^-chlor- and bromdinitro-benzenes, CeHgCl(N02)2, and CsHjBr^NOj)^ (i,
3, 4. CI and Br occupy i) ; the first exists in three modifications, which melt at
36.3°, 37°, and 38.8° {Berichte, g, 760) ; the second consists of yellow plates,
melting at 59.4°.

Trinitro-chlorbenzene, CgH2Cl(N02)3 (i, 3, 5, CI), Picryl Chloride, is
obtained from picric acid by the action of PCI5. It melts at 83°. It is converted
into picramide, C5H2(NH2)(N02)3, with ammonia, and into picric acid when
boiled with soda. •

DERIVATIVES OF TOLUENE.

By nitration toluene yields chiefly two isomeric nitro -toluenes,
C6H4(N02).CH3, the solid para-compound and the liquid ortho-
derivative. They can be separated by fractional distillation. The
para-nitrotoluene predominates when the nitration occurs at an ele-
vated temperature and fuming acid is employed, but at low temper-
atures, and with nitric and sulphuric acids, the ortho-body is in
greater quantity (about 66 per cent.).

Paranitro -toluene (i, 4) forms large prisms; melts at 54° and boils at 237°.
Chromic acid oxidizes it to paranitro-benzoic acid ; paratoluidine is the product
of its reduction. Chlorination at 150° produces paranitro-benzal chloride, CjH^
(N02).CHCl2, which forms /-nitro-benzaldehyde with SO^Hj.

Orthonitro-toluene (i, 2) is liquid, and boils at 223°; its specific gravity at
23° is 1. 163. It is also formed in the partial reduction of dinitro-toluene with
ammonium sulphide, and the replacement of the NHj-group of the resulting amide
by hydrogen. Chromic acid destroys it, but when oxidized with HNO3, MnO^K,
or potassium ferricyanide, orthonitro-benzoic acid is the product ; it yields ortho-
toluidine by reduction. Bromine added to orthonitro-toluene at 170° produces
dibromanthranilic acid : —

C3H^(NO,).CH3 + 2Br, = CeH2Br3(NH2).C02H + 2HBr.

{CIT
nhV H O

is nitrated, and the amido-group replaced by hydrogen. (Preparation, Berichte,
22, 831.) It melts at 16° and boils at 230°. When oxidized, it yields metanitro-
benzoic acid ; when reduced, metatoluidine.

Ordinary a- Dinitro-toluene, CgH3(N02)2.CH3 (i, 2, 4 — CH3 occupying i),
is obtained from toluene, and from (l, 4)- and (l, 2)-nitrotoluene on boiling with
fuming nitric acid (together with »«.nitrotoluene, Berichte, 18, 1336). It crystal-
lizes in long needles, melts at 71° and boils near 300°. It can be oxidized to
dinitro-benzoic acid, from which we Obtam (i, 3)-dinitro-benzene. Ammonium
sulphide reduces the N02-group (in 4), and forms amido-nitrotoluene. Sym-
metrical dinitrotoluene (i, 3, 5) is formed from dinitro-paratoluidine, and melts
at 92°.

AMIDO-COMPOUNDS. 59I

Trinitro-toluene, C5H2(N02)3.CH3 (i, 2, 4, 6— CHj occupying i), is pre-
pared by heating toluene with nitric and sulphuric acids. It melts at 82°, and is
oxidized with difficulty. It forms molecular compounds with benzenes and ani-
lines (p. 588), and yields symmetrical trinitrobenzene when heated with nitric acid.
The nitro-derivatives of the higher hydrocarbons have been mentioned with the
latter.

NITROSO-COMPOUNDS.

Nitroso-benzene and nitroso-naphthalene are the only known de-
rivatives in which the nitroso-group occupies the position of benzene-
hydrogen. The so-called nitroso-phenols (see these), according to
latest researches, possess a very different constitution, although they
give the nitroso-reaction (p. 107).

Nitroso-benzene, CgH5.NO, is produced by the action of NOCl or NOBr
upon a solution of mercury diphenyl, (C5H5)jHg, in benzene or carbon disulphide,
or by letting nitrous acid act upon diphenyl tin chloride, (CgH5)jSnCl2. It is only
known in solution, and has a sharp odor and green color. Tin and hydrochloric
acid reduce it to aniline : —

CeHjNO + 2H, = CgHj.NH, + H,0.

When digested with aniline acetate, azobenzene is formed : —

QH^.NO + NH^.C^H^ = CeH5.N:N.CeH5 + H,0.

By oxidizing quinodioxime with alkaline potassium ferricyanide, there results a
compound, which is very probably Dinitrosobenzene, C5H4(NO)2 (i, 4). It has
a golden yellow color, is insoluble in nearly all solvents and, when heated, sub-
limes with partial decomposition. Upon oxidation with HNO3, it yields /dini-
trobenzene, and when reduced, ^-phenylenediamine. When boiled with HCl-
hydroxylamme it is reconverted into quinodioxime, C5H4(N.OH)2 (Berichte, 20,
61S).

p Dinitroso-toluene, C5H3(NO)2.CH3, from toluquinone-dioxime, closely
resembles the benzene derivative. It has an odor somewhat like ClOH. It de-
tonates when heated to 144° (Berichte, 21, 734).

AMIDO-COMPOUNDS.

These are produced by the substitution of amido-groups for the
hydrogen of benzene : —

C„H,NH, C,H,(NH,), CeH3(NH,),.

Amidobenzene. Diamido-benzene. Triamido-benzene.

Or, they may be considered as ammonia derivatives, from which
might be concluded the existence of primary, secondary and ter-
tiary amines of the benzene series (p. 157) : —

C3H5.NH, (CgHANH (C3H5)3N.

Phenyiamine, Diphenylamine. Triphenylamine.

592 ORGANIC CHEMISTRY.

The true analogues, e.g., CeHj.CHa.NHj, of amines of the fatty
series are obtained when the hydrogen of the side-chains is replaced
by the amido-group. They are considered later.

The amido-compounds of the benzene series are prepared almost
exclusively by the reduction of nitro-derivatives. The most im-
portant methods of reduction are : —

(i) The action of ammonium sulphide in alcoholic solution
(Zinin in 1842) : —

CeH^.NOj + 3H,S = C^H^.NH^ -f aHp + 3S.
/

The nitro- compound is dissolved in alcohol, concentrated ammonia added and
hydrogen sulphide conducted into the hot mixture as long as sulphur is precipi-
tated. Filter and concentrate the filtrate. In using this reaction with the di-
and tri-nitro-compounds only one nitro-group is reduced at first, and in this
manner it is therefore easy to obtain intermediate products, like the nitroamido-
compounds. It is only by continued heating that the second nitro-group is
reduced.

In the case of chlor-nitro-benzenes the nitro-group is only reduced by ammo-
nium sulphide when it is not adjacent to the chlorine or another nitro-group ; in
the reverse 'instance sulphur will replace the chlorine or a nitro-group [Berichte,
II, Z056 and 1156).

(2) Action of zinc and hydrochloric acid upon the alcoholic
solution of nitro-compounds (Hofmann) ; or iron filings and acetic
or hydrochloric acid (Bechamp). The latter method is applied
technically in the manufacture of aniline or toluidine ; the reduc-
tion is accomplished by the nascent hydrogen and the resulting
ferrous oxide : —

CsH5.NO, -f 6FeO + H,0 = CeH^.NH, + aFe.Og.

(3) Action of tin and hydrochloric acid (or acetic acid)
(Roussin) : —

CeHj.NO, -f- 3Sn + 6HC1 = CeH^.NH, -f- aSnCl, -f 2H,0.

Stannous chloride reacts similarly : —

CeH5.NO, -f sSnCl, -f 6HC1 = CeHg.NH, -f sSnCl^ + 2H,0.

This method serves also for the quantitative determination of
the nitro-groups {Berichte, n, 35 and 40).

Pour fuming hydrochloric acid over the nitro-compound and gradually add the
calculated quantity of granulated tin (i^ Sn for iNO,) ; after a little time,
usually without heating, a violent reaction ensues, and the tin and nitro-derivative
both dissolve. The solution contains a double salt, e. g., (CjHj.NHj.HCl),
SnCl^, formed by the HCl-salt of the amide combining with tin chloride. These
salts generally crystallize well. The tin is precipitated from the hot solution by
hydrogen sulphide, the sulphide is filtered off and the filtrate contains the hydro-
chloride salt of the amido- compound. Alkalies will set the latter free. Some-

AMIDO- COMPOUNDS. 593

times in using tin and hydrochloric acid chlorinated amido-compounds are pro-
duced, therefore, in such cases it is advisable to substitute acetic acid. {Berichte,
20, 1567).

In this procedure, which is principally employed in laboratories,
all the nitro-groups present in a compound are simultaneously
reduced. The reduction can, however, be limited to single groups
(Kekule), if we apply an alcoholic HCl solution and take only half
the tin requisite for complete reduction ; thus, nitraniline results
from dinitrobenzene. Partial reduction can also be effected by the
action of the calculated quantity of stannous chloride in alcoholic
solution {Berichte, ig, 2161).

Other reducing agents, finding occasional application, are : sodium arsenite, zinc
dust (in alcoholic or ammoniacal solutions), tin and acetic acid {^Berichte, 15,
2105), and HI and phosphorus iodide. Sodium amalgam, on the other hand,
reduces nitro- to azo-compounds. A procedure, very well adapted for unsaturated
nitro-compounds, consists in the use of ferrous sulphate and baryta-water or
ammonia (^Berichte, 15, 2299).

Only traces of amido- derivatives can be had by heating the haloid compounds,
e. g., CjHjBr, with ammonia ; the same may be remarked of the phenols. Both
classes of compounds, however, react more readily providing nitro-groups exist in
the benzene nucleus. Thus, when (1,2)- and (i, 4)-chlor- and brom-nitroben-
zenes are heated with alcoholic ammonia, the corresponding nitranilines are pro-
duced, whereas the meta- compounds do not react (p. 588).

Amido- derivatives are similarly formed from the nitranisoles (alkylized phenols),
when heated with aqueous or alcoholic ammonia to 180-200° {Berichte, 21 1541) :

C,H^(N0,).0.CH3 + NH3 = CeH,(NOj,).NH, + CH3.OH.

Here again it is the para- and ortho-compounds which react, not the meta- variety.
The halogen atoms and oxyalkyls are more reactive in the presence of two or
three nitro-groups. Thus a-chlor- and brom-dinitrobenzene yield dinitraniline (p.
588) ; dinitroanilines are formed from the a- and /3-dinitrophenols (their ethers)
(Annalen, 174, 276; Berichte, 21, 1541): —

C,H3(N02)2.0.CH3 + NH3 =C5H3(NO,),.NH, -f CH3.OH;

and chrysanisic acid is obtained from dinitroanisic acid.

In a few ortho-dinitrocompounds ammonia (also aniline) can replace a nitro-
group by NHj (Laubenheimer), thus ortho-dinitrobenzene yields ortho- nitraniline,
^-dinitrochlorbenzene yields nitroamido- chlorbenzene (p. 587). The phenols can
also be directly transformed into amido-benzenes by heating them to 300° with
ammonia- zinc chloride (ZnCl^.NHj), especially in the presence of ammonium chlo-
ride {Berichte, 19, 2916; 20, 1254) : QH^-OH + NH3 = CjHs.NHj + H^O.
About 70 per cent, of amines are obtained by this method. The naphthols react
even more readily. The divalent phenols react in like manner with aniline {Be-
richte, 16, 2812 ; 17, 2635).

The secondary and /^rriarjc phenylamines cannot be prepared from the primary,
e.g., C5H5.NH2, by action of C3H5CI or CsHjBr. The secondary are obtained

50

594 ORGANIC CHEMISTRY.

by heating the anilines with HCl-anilines (like the secondary acid amides) (p.
255) ■■—

CeH5.NH,.HCl + CeH^-NH, = (CeH5)3NH + NH3.HCI.

The tertiary phenylamines are prepared by treating the potassium compounds,
C5H5.NK2 or (CeH5)jNK, with C^HjEr :—

C.H^.NK, + 2C,H,Br = (C.HJjN + 2KBr.

The amido-derivatives of the benzene hydrocarbons are organic
bases : they combine with acids to form salts, just as the amines do,
and are freed again by alkalies. But they are far more feeble bases
than the alkylamines, because the phenyl group possesses a more
negative character (p. 557). They do not show an alkaline reaction.
The secondary phenylamines, e.g., (C6H5)2NH, are even less basic ;
their salts are decomposed by water, and tertiary triphenylamine is
not capable of producing salts.

When negative groups enter the primary phenylamines, they
further diminish their basic character ; the salts of substituted
anilines, like CeHgClj.NH, and C6H3(N02)2.NH2, are decomposed
by water, or are not produced.

The behavior of the phenylamines towards nitrous acid is very
characteristic ; it is perfectly analogous to that of the alkylamines
(p. 157). The primary phenylamines exchange the group NH, for
OH, and form phenols : —

C.H^.NH, + NO^H = CeHg.OH + N, + H^O.

Diazo-compounds and diazoamido-derivatives (see these) are inter-
mediate products. The secondary phenylamines, e. g., (C6H5)2NH
and CeHj.NH.CHs, yield nitrosoamines (p. 164): —

(C,H,),NH + NO.OH = (CeHJ.N.NO + H,0;

while from .tertiary amido-derivatives we get the nitroso-products of
the benzene nucleus : —

C,H5.N(CH,), yields CeH^(N0).N(CH3),.

Only the primary phenylamines are adapted to the formation ot
carbylamines and mustard oils (pp. 287 and 279). Furfurol com-
bines with all the amido-benzene derivatives, forming intense red-
colored compounds.

On boiling the anilines with hydrochloric acid and concentrated nitric acid the
amido-group is displaced and chlorbenzenes (together with chlorphenols) are pro-
duced. "With HBr or HI and nitric acid the products are bromine and iodine
derivatives [jBerichte, 18, 39).

AMIDO COMPOUNDS. 595

On heating the HCl-salts of methyl and dimethyl aniline to 300°, the methyl
group is transposed, and we get toluidine, xylidine, etc. (p. 586).

, C,H,.N(CH3), yields CeH,(CH3).NH.CH3 and CeH3(CH3),.NH3.

A similar alkylizing of the benzene nucleus occurs on heating the HCl-anilines
with alcohols to 300°, or the anilines with alcohols and ZnClj to 280° {Berichte,
16, 105; 18, 132).

Aniline, CsHj.NH^
Toluidine, CjH^.NH^
Xylidine, CjHj.NHj
Cumidine, CgHjj.NHj

Aniline, CeHj.NHj, amidobenzene, was first noticed by Unver-
dorben in 1826, in the dry distillation of indigo (crystallin), and
later by Fritsche in the distillation of indigo with caustic potash
{Anilin, 1841). Runge discovered (1834) it in coal-tar, and called
it cyanole. Zinin was the first to prepare it artificially (1841), by
reducing nitrobenzene with ammonium sulphide. It is formed in
the dry distillation of many nitrogenous substances, for example,
bituminous coal, bones, indigo and isatin. At present it is exclu-
sively made by reducing nitrobenzene.

In the preparation of aniline on a large scale, nitrobenzene is heated with iron
filings and hydrochloric acid (p. 592). The product of the reaction is mixed with
lime and distilled with superheated steam. In a small way the reduction is best
executed with tin and hydrochloric acid.

Aniline is a colorless liquid with a faint, peculiar odor, and boils
at 183° (corr.); its specific gravity at 6° is 1.036. When perfectly
pure it solidifies on cooling, and melts at — 8°. It is slightly
soluble in water (i part in 31 parts at 12°) but dissolves readily in
alcohol and ether. It shows a neutral reaction with litmus. When
heated it expels ammonia from its salts, while in the cold ammonia
separates it from its salts. Exposed to air aniline gradually assumes
a brown color, and resinifies. Bleaching lime imparts a purple
color to the solution. When a pine shaving is moistened with
aniline salts it becomes yellow in color. On adding sulphuric acid
and a few drops of potassium chromate to aniline, a red color
appears ; later it becomes an intense blue.

As a base aniline unites directly with acids, and also with some salts — ("C5H,N)2.
SnCl^, (CgHjNyj.CuSO^. Its salts- crystallize well, and dissolve readily in
water. The HCl-salt, CgH,N.HCl, forms deliquescent needles; platinic chlo-
ride precipitates a yellow-^lored double salt, (C6H,N.HCl)2.PtCl4, from the
alcdholic solution. "The inmate, CgH^N.NOjH, crystallizes in large rhombic
plates; the oxalate, (CjHjM^.C^O^Hj, obtained by mixing the alcoholic solu-
tions, forms rhombic prisms.

596 ORGANIC CHEMISTRY.

On warming aniline with potassium, the hydrogen of the atnidogroup is re-
placed with formation of the compounds CgHj.NHK and C^Hj.NKj : sodium
does not react until heated to 200°. It acts more readily providing one hydrogen
atom of the amidogroup is substituted by acid radicals (as in acetanilide,
C5H5.NH.C2H3O), or if halogen atoms be present in the benzene nucleus ; in
this case the halogen is reduced by the nascent hydrogen. The sodium com-
pounds are oxidized to azo-compounds, when they are exposed to the air.

ANILINE SUBSTITUTION PRODUCTS.

These are obtained : (i) By the direct substitution of aniline.
The anilines, like the phenols, are more susceptible of substitution
than the benzenes. The action of the halogens is so energetic that
the reaction requires to be moderated. When chlorine or bromine
water acts upon the aqueous solution of aniline salts, their hydrogen
atoms are directly substituted. Nitric acid converts aniline into
nitrophenols. To get the mono- and di-substitution products, it is
necessary to employ as points of departure the acid anilides, e. g.,
acetanilide, CeHj.NH.QHjO; these are first substituted, and the
substituted anilines separated from them by boiling with alkalies
or hydrochloric acid, or with sulphuric acid.

On allowing chlorine and bromine (in aqueous solution, or in vapor form) to act
upon acetanilide suspended in water, only para-compounds are produced (p. 589),
because the ortho-derivatives formed at the same time immediately pass into
dihalogen derivatives. In the nitration of acetanilide mono-derivatives of the
para-, ortho- and meta-series are formed. By nitration in presence of much sul-
phuric acid, meta-nitro-derivatives predominate (p. 589).

The union of the amid-group and the transposition into an acid group occur
simultaneously (giving rise to a meta-substitution product, p. 589). Chlorine and
bromine react in the same way with aniline and toluidine in the presence of con-
centrated sulphuric acid or hydrochloric acid {Berichte, 22, 2539 and 2903 ; 23,
1643-).

When ortho- and para-substituted anilines are chlorinated, they almost invariably
furnish tri-substituted products (l, 2, 4, 6), whereas the meta-series yield tetra-
and penta-substitution products yBerichte, 15, 1328).

Iodine is capable of directly substituting the anilines, as the re-
sulting hydriodic acid is taken up by the excess of aniline : —

2C,H5.NH, -f I, = CeH J.NH, -f CeH,.NH,.HI.

(2) By the reduction of halogen nitrobenzenes by means of tin
and hydrochloric acid, or ammonium sulphide (p. 592) ; thus, the
three CeHjBr.NOj yield the corresponding CeH^Br.NHj.

(3) The nitranilines can be prepared by heating haloid nitro-
benzenes to 150-180° with alcoholic ammonia; or by heating the
ethers of the nitrophenols, e.g., C6H4(N02).O.C2H5, with aqueous

ANILINE SUBSTITUTION PRODUCTS. 597

ammonia. In both instances the para- and ortho-compounds, and
not the meta-, react (p. 589).

(4) The halogen anilines can be obtained from the nitro-anilines
by first replacing the amido-group by halogens. This is accomplished
through the diazo-compounds. The next step is, then, to reduce
the nitro-group : —

The ortho-compounds are weaker bases than the para- and meta-.

Ortho- and Meta-chloraniline, from the corresponding chlornitro benzenes,
are liquids; the first boils at 207°; its specific gravity at 0° is 1.23; the second
boils at 230° ; its specific gravity at 0° is 1.24. Parachloraniline, formed from
(i, 4)nitraniline and nitrochlorbenzene, and by the chlorinatlon of acetanilide,
crystallizes in shining, rhombic octahedra, which are somewhat soluble in hot
water. It melts at 70-71° and boils at 230-231°, with scarcely any decomposi-
tion. The HCl-salt is slightly soluble in cold water.

Ortho-bromaniline, CgH^Br.NH,, from o-(Br.NOj) and ^-(NHj.NOj), crys-
tallizes in needles, melting at 31.5° and boiling at 229°. Metabromaniline, from
OT-nitroaniline and z«-bromnitrobenzene, melts at 18° and boils at 251°. Para-
bromaniline, from /-nitraniline and /-nitrobrombenzene, is easily obtained by
conducting bromine vapor into acetanilide. It crystallizes in shining, rhombic
octahedra, and melts at 63° (66°). The action of sodium upon the ethereal solu-
tion produces benzidine. When distilled it breaks up into aniline, a-dibromaniline
and a-tribromaniline.

Ortho-iodoaniline, CjH^I.NHj, prepared by the reduction of o-nitroiodoben-
zene, melts at 56.5°. It is very volatile {BericAte, 21, Ref. 348). Metaiodoani-
line, from »«-nitraniline, forms silvery laminse, and melts at 27°- Paraiodoani-
line is formed from ^-nitroiodobenzene and by the direct action of iodine upon
aniline, or by the action of chlor-iodine upon acetanilide. It consists of needles
or prisms, melting at 63°, and somewhat soluble in hot water. With ethyl iodide
it yields ethyl-aniline: CsH^LNH, + C^HJ = CeH5.NH.CjH5 + I^.

a-Dichloraniline, CgHjCl^-NHj, from dichloracelanilide {1,2, 4 — NH^ in l),
crystallizes in needles, and melts at 63°. /3-DichIoraniline, from nitro- (i, 4)-
dichlorbenzene (p. 581), melts at 54° {Annalen, 196, 215).

a-Dibromaniline, CeH3Br2.NH2(l,2,4 — NHjin i),is obtained from dibrom-
acetanilide and from nitro-(i, 3)dibrombenzene (melting at 61°, p. 582) ; it melts
at 79°. /3.Dibromaniline, from nitro-(i, 4)-dibrombenzene, melts at 51-52°.

a-Trichloraniline, CjHjClj.NHj (chlorine in i, 3, 5), is formed by con-
ducting chlorine into the aqueous solution of HCl- aniline. It melts at 77.5° and
boils at 260°. It no longer combines with acids." Symmetrical trichlorbenzene
is obtained from it by substituting H for NHj. /3-Trichloraniline, (l, 2,4, 5

NHj in i), from nitro-(l, 2, 4)-trichlorbenzene, melts at 96.5° and boils at

270°.

a-Tribromaniline, CjHjBrg.NHj (bromine in i, 3, S), is formed on conducting
bromine vapors into aqueous HCl-aniline ; it crystallizes in long needles, melts at
119°, and forms salts with difficulty {Berichte, 16, 635). It yields symmetrical
tribrombenzene. /3-Tribromaniline (I, 2, 4, 5 — NHj, in i) is obtained from
ordinary tribrombenzene (i, 2, 4) by nitration and reduction, and does not melt,
even at 130°.

598 ORGANIC CHEMISTRY.

Niiranilines, Q,^^(;HO^.'^Yi.^ :—
M. P.

sH^I

(«,2)

(1.3)

(1.4)

71°

114°

147°

102°

63°

147°

118°

90°

172°.

NH2

NO 2
C H |N^2

C H /N°2

The three nitranilines can be obtained from the three corresponding dinitro-
benzenes, by incomplete reduction with ammonium sulphide (p. 592). Ortho-
and para- nitranilines are also produced from the corresponding haloid nitroben-
zenes, the ethers of nitrophenols and dinitro-benzenes, upon heating with ammo-
nia (p. 588); also by the nitration of acetaniline. The easiest course to pursue
in making the three compounds, is to dissolve aniline-sulphate in an excess
of concentrated sulphuric acid, and add the calculated amount of fuming nitric
acid. Precipitate with water and distil in a current of steam, when the ortho- and
the meta-products pass over, while the para remains. The para and meta occur
rather abundantly, the ortho only in small amount [Berichte, 10, 1716; 17, 261).

Ortho-nitraniline (i, 2), is most easily obtained by heating o-nitranilinesul-
phonic acid (from acetyl anilinesulphonic acid) with hydrochloric acid to 170°
(Berichte, 18, 294), or by the action of ammonia upon o-nitrophenol at 160°
(Berichte, ig, 1749). It forms yellow needles, melting at 71°) i' dissolves in
water and alcohol more readily than its isomerides, and is more reactive. It yields
(i, 2)-diamido-benzene when reduced.

Metanitraniline (i, 3) consists of long yellow needles, melting at 114°.
Water decomposes its salts. By reduction it yields (l, 3)-diamido-benzene.
Para-nitraniline (i, 4) forms yellow needles or plates, melts at 147°, and yields
(l, 4)-diamido-benzene.

Of all the HCl-salts of the nitranilines that of o-nitraniline is most easily decom-
posed by water, then follows /-nitraniline, while the salt of metanitraniline is the
most stable. From this it is evident that the basicity of the nitranilines succes-
sively diminishes in the order: meta-, para-, ortho [Berichte, 17, 2719). The
same is observed in the deportment of the aceto-nitranilines with alkalies [Berichte,

19, 337).

When ortho- and para-nitranilines (not meta) are boiled with alkalies, they part
with NHg, and are converted into their corresponding nitrophenols, C5Hj(N02).
OH; the di- and tri-nitranilines react even more readily.

Dinitranilines, C8H3(N02)2.NH2. The so-called adinitrartiline is obtained
from dinitrochlor- and dinitrobrom-benzene, also from a-dinitrophenol (its ether),
when they are treated with ammonia in the heat. It melts at 182°, and by elimi-
nation of the NHj yields ordinary dinitro-benzene (1,3). Hence, its structure is
(I, 2, 4— NHj in I).

P-Dinitrattiline is obtained from ^-dinitrophenol. It melts at 138°, and also
yields (i, 3)-dinitro-benzene, hence its structure is (i, 2, 6 — with NPIj in i).

Trinitraniline, CjH2(N02)3.NHj, called Picramide, is obtained from picric
acid through its ether, or by means of picryl chloride (p. 590). The latter reacts
with ammonia, even in the cold. It forms orange-red needles, and melts at 1 85°.
Its structure is analogous to that of picric acid (i, 2, 4, 6 — NHg in l). It forms
picric acid when heated with alkalies : —

CeH2(N02)3.NH2 + KOH = CeH2(N02)3.0I<; + NH3.

NHj NH

Nitroso-anilines, CgH^^ or CgH^/ . These compounds are pro-'

^NO ^N.OH

ALCOHOLIC ANILIDES. 599

duced when the nitrophenols or quinoximes are heated with ammonium chloride
and ammonium acetate (JBerichte, 20, 2474; 21, 684) : —

CeH.(S.OH y'^Ws C,H /NH,

Quinoxime. Nitrosoaniline.

The nitroso-toluidiues are similarly obtained from nitrosocresols (5^«V;4/^, 21,
729)..

/-Nitroso-aniline, CeH4^(NO)(NH2), crystallizes in steel-blue needles, melt-
ing at 174°. Its solutions (in benzene, water) show a bright green color. It dis-
solves in sodium hydroxide, forming a sodium salt. When boiled with this reagent
it is again resolved into ammonia and nitrosophenol. HCl-Hydroxylamine con-
verts it into quino-dioxime, CgH^fN.OH),. Phenylhydrazine changes it to/-
phenylenediamine and a nitroso-diazo compound (Berichte, 22, 623).

ALCOHOLIC ANILIDES.

We find that, as in the amines of the fatty series, so in aniline,
the hydrogen of the amido-group can be replaced by alcohol and
acid radicals. The alkyl derivatives are formed in the same man-
ner as the amines of the paraffin series (p. 157), by the action of
the alkyl bromides and iodides upon aniline. This occurs mostly
at ordinary temperatures. They can be directly produced by heat-
ing HCl-anilines with the alcohols to 250°. Alkyl chlorides are
first produced, but they subsequently act upon aniline. The alkyli-
zation is more easily effected by using the HBr-salts {Berichte, 19,

1939)-

The tertiary derivatives, e.g., CeHs.NCCjHs)^, combine further
with the alkylogens, forming ammonium compounds, which moist
silver oxide or lime converts into ammonium hydroxides : —

(cSSl^^ yields (cfii;):}N-oH.

The alkylic anilines can, vice versa, be re-formed. Dimethyl aniline results when
the ammonium hydrate or its haloid salts are distilled. This product, by further
heating with HCl or HI to 150°, or by the distillation of its hydrochloride, regen-
erates methyl-aniline and aniline (p. 160). When dimethyl aniline hydrochloride
is heated to 250-300°, a rearrangement occurs, the alkyls enter the benzene nu-
cleus, first in the para-position (4), then the ortho-positions (i) and {6). /-Tolui-
dine, metaxylidine and finally mesidine are produced. o-Toluidine deports itself
similarly (Berichte, 21, 640). When acetyl chloride acts upon the dialkyl anilines
the alkyl-gronps split off quite easily {Berichte, 19, 1947).

The aniline salts form ferrocyanogen salts with potassium ferrocyanide ; these
serve to separate the anilines {Annalen, igo, 184).

The methylated anilines are technically applied in the production
'of aniline dye-stuffs. They are formed on heating aniline together
with HCl-aniline and methyl alcohol to 220°. A better course is

6oo ORGANIC CHEMISTRY.

to conduct CH3CI into boiling aniline. Methyl and di-methyl
aniline occur in both instances, together with unaltered aniline.
Consult ^i?w,^/(?, 10, 795, 22, 1005, for their separation and detec-
tion.

Methyl Aniline, CeHs.NHCCHs), , is obtained pure from its
nitroso-compound by reduction with tin and hydrochloric acid, or
by the saponification of the acetyl derivative. The latter can be
prepared from the sodium acetanilide, C6H5.N(Na).C2H30, by treat-
ment with methyl iodide {Berichte, 17, 267). It boils at 190-191°,
has an odor resembling that of aniline and a specific gravity at 15°
of 0.976. Its salts (with HCl and HjSOi) do not crystallize and
dissolve in ether. Hence, dilute sulphuric acid in ethereal solution
does not separate methyl aniline in crystalline form, as it does with
aniline. Bleaching lime imparts no color to it. With acetyl chloride
or acetic anhydride, it forms the crystalline acetyl derivative, CeHj.
N(CH3).C2H30, which melts at 101°, and boils at 245°. When
methyl aniline is heated to 330°, it is transformed into paratolui-
dine, C6H«(CH3).NH2.

Nitroso-methyl-aniline, &„^ VN.NO, Phenyl methyl-nitrosamine (p. S94)>

is produced by the action of nitrous acid upon methyl aniline (also other second-
ary phenylamines), or better by KNOj upon the solution of its HCl-salt. It
separates as a brown oil, which can be extracted with ether (jBerichte, 19, 2123
and 18, 1997 ; Annalen, igo, 151). When distilled with steam it yields a yellow,
aromatic-smelling oil, that solidiBes in the cold, and melts at 12—15°. I' cannot
be distilled alone. It shows the nitroso reaction (p. 107) and does not combine
with acids. HgNa, or zinc dust and acetic acid reduce it to methyl phenyl
hydrazine. It regenerates methyl aniline with zinc and sulphuric acid, tin and
hydrochloric acid, or by gently heating with SnClj. Reaction with anilines or an
alcoholic potash solution accomplishes the same [Berichte, 11, 757). See Berichte,
17, 2668 upon the action of the nitrosamines upon the anilines.

When acted on by alcoholic hydrochloric acid methyl-aniline-nitrosamine
rearranges itself to /-nitrosomethylaniline (^Berichte, 19, 2991 ; 21, Ref.
228) :—

^|^=\n.NO yields NO.C5H^.NH.CH3.

/-Nitrosomethylaniline, C5H.(NO).NH.CH3, is perfectly analogous to
/-nitrosodimethylaniline (see below). Its HCl-salt is not very stable. The free
base forms large crystals with metallic lustre and mells at 118° C. It is soluble in
dilute sodium hydroxide, forming the sodium compound, CjHjNjO.NaOH, from
which it is again liberated by carbon dioxide. It therefore probably possesses a
structure analogous to that of the nitrosophenols or quinoximes [Berichte, 20, 532,
1252):—

.NH.CH3 .NH.CH3 ,,N.CH3

C,h/ _C,h/|>0 or C,h4

When heated with sodium hydroxide /nitrosomethyl aniline is decomposed into
/-nitrosophenol and methylaniline : —

C5H4(NO).NH.CH3 -f HjO = CgH^CNOj.OH + NH^CH,.

DIMKTHYL ANILINE. 6oi

Methenyl amido-thiophenol and similar thiazole-like compounds are produced
upon heating methyl and dimethyl aniline with sulphur {Berichte, 21, 60).

Dimethyl Aniline, C6H5.N(CH3)2, is obtained pure by dis-
tilling trimethyl-phenyl ammonium hydrate or its HCl-salt. The
commercial article contains as much as 5 per cent, of methyl
aniline. It is an oil boiling at 192° and solidifying at + 5° ; its
sp. gr. is 0.955. Its salts do not crystallize. It forms an acetate,
C6H5N(CH3)2.C2H402, with acetic acid j this decomposes again on
distillation. Hypochlorites do not color it. It forms QHj.N
(0113)31 with methyl iodide.

Dimethyl aniline is remarkable because in it, as in the phenols, there is a re-
active H-atom in the benzene nucleus. The action of nitrous acid, or better,
sodium nitrite, upon the HCl-salt [Berickte, la, 523) produces the HCl-salt of

/-Nitroso-dimethyl Aniline, CgH^/^^^a)! I^Berichte, 20, 1252). This

forms needles, which are not very soluble in water. The free base, separated from
its salts by sodium carbonate, crystallizes in green, metallic-like laminae, melting
at 85°. It yields dyestuffs with phenols and anilines. KMnO^ and ferricyanide
of potassium oxidize it to nitro- dimethyl-aniline. Warm, dilute caustic soda
decomposes it into dimethyl aniline and paranitroso-phenol (p. 600).

/-Nitro-dimethyl Aniline, C5H^(N02).N(CH3)2, is obtained in the oxidation
of the nitroso-compound and by the action of fuming nitric acid (l mol.) upon
dimethyl aniline in glacial acetic acid (10 parts) solution; it melts at 162°. Meta-
nitrp- dimethyl Aniline is produced together with the para-compound. It forms
salts with acids [Serickte, ig, 545). Dinitro-dimethyl Aniline (i, 2, 4),
obtained by. further nitration (see Berickte, ig, 2123; 18, 1997), is also formed
from a-dinitrochlorbenzene (p. 588), and trimethylamine (^Berickte, 15, 1234);
it melts at 78° and is easily decomposed by potash into dimethyl aniline and
a-dinitrophenol. Further nitration produces trinitrophenyl methylnitramine, CjH2
(N02)3.N(CH3).(N02) {Berickte, 22, Ref. 343).

/-Amido-dimethyl Aniline, C5Hj(NH2).N(CH3)2, dimethyl-paraphenylene
diamine, is formed by the reduction of the nitroso- and nitro-compounds. It
may be obtained by the ■ decomposition of helianthine {Berickte, 16, 2235). It
melts at 41° and boils at 257°. In acid solution it gives a dark blue coloration
(methylene blue) with hydrogen sulphide and ferric chloride, and answers as a
sensitive reagent for hydrogen sulphide.

Other groups can replace a benzene hydrogen in dimethyl aniline. For
example, an acid chloride (of dimethyl amido-benzoic acid) and ketones are pro-
duced by the action of COClj. Benzoyl chloride (see Berickte, 18, 685), benzyl
chloride and chloroxalic ester react similarly, whereas by the action of chlor- or
iod-acetic acids or their esters a methyl group is displaced and phenylglycocoll
results {Berickte, 17, 2661) : —

C,n,.^{CU,)^ + CH^T.CO.H = CeH,.N(CH3).CH2.C02H + CH3I.

A methyl group is similarly split off by acetyl chloride or benzyl chloride

(P- 599)-

Dimethyl aniline, like the phenols, forms condensation products with aldehydes
(oil of almonds, furfurol, chloral, etc.); it combines with chlorides to yield
phthaletnes and green dyestuffs, and with benzotrichloride, CgHj.CClgjto form
the so-called malackite green. A condensation of several benzene groups takes

6o2 ORGANIC CHEMISTRY.

place, with the production of compounds which are allied to triphenyl methane
and the aniline colors.

Dimethyl aniline and chloral condense to '--6'^4\ cHfOHl^CCl ''"^^'■^ yields
CgH /^(^a)^ with alkalies (Berichte, ig, 365).

The so-called Azylines are tetra-alkyl-para-diamido-azobenzenes (see these) :
R2N.C8H^.N2.CgH4.NR2. They are formed when nitric oxide acts upon tlie
tertiary anilines. Nitric acid converts the dialkyl anilines into nitramines, e, g.,
tri-nitrophenylnitramine, C5H2(N02)3.N(CH3)(N02) (p. 164).

Ethyl Aniline, CjH 5. NH.CjHj, boils at 204°; its specific gravity at 1 8° is
0.954. Its nitrosamine derivative, Q^M^.T^{^0).C^^,\s a yellow oil, with an
odor resembling that of bitter almonds; it does not unite with acids and cannot be
distilled (^Berichte, 8, 1641). Alcoholic hydrochloric acid converts it into /-Ni-
troso-Ethyl Aniline, C8H4(NO).NH.C5H5, which crystallizes in green leaflets,
melting at 78°.

Methyl Ethyl Aniline, C|5H5.N(CH3).(C2H5), boils at 201°. Its compound
with CH3I is identical with dimethyl-aniline-ethyl iodide ; methyl-ethyl aniline-
ethyl iodide is also identical with diethyl aniline-methyl-iodide — an additional
proof that the five affinities of nitrogen have equal value (p. 166 and Berichte, 19,
2785). Ethyl iodide is set free from all these ammonium iodides when they are
heated with caustic potash.

Diethyl Aniline, C5H5.N(C2H3)j, boils at 213°; its specific gravity at 18° is
0.939. When heated with ethyl iodide it forms CsH5.N(C,H5)3l, from which
silver oxide separates the strong ammonium base, C5H5.N(C2H5)3.0H ; the latter
decomposes on distillation into diethyl aniline, ethylene and water. The nitroso-

compound,Q,^/-^^'^ 5'*, forms large, green prisms, which melt at 84°, and

yield nitroso-phenol and diethylamine, when boiled with dilute caustic soda.

AUyl Aniline, CgH5.NH.C3H5, from aniline and allyl iodide, boils at 208°; it
yields quinoline, CgHjN, when distilled over heated lead oxide.

The derivatives with divalent alcohol radicals are formed the same as the alkyl
anilines. , Methylene-diphenyl-diamine, (CgH5.NH),2CH2, from aniline and
methylene iodide, is a thick liquid. Aniline yields methylene aniline, CjH,.
N:CHj (?), when acted upon by formic aldehyde. Bright crystals [Berichte, 18,
3309, Ref. 71).

Ethylene-diphenyl-diamine, (C8H5.NH),^CjH4, from aniline and ethylene
bromide, is crystalline, and melts at 65°. Ethylene aniline condenses with aide-

CH2.N(CeH5)
hydes, forming bases like | ^CH.CHg, which are again resolved into

CHj.N^CsHj)
their components by acids [Berichte, 20, 732). Isomeric ethidene-diphenyl
diamine, (CgHj.NHjj.CH.CHj, is produced in the cold from aniline and alde-
hyde. It is amorphous. Similar compounds are produced with other aldehydes,
^. ^., valeral, acrolein and furfurol. With chloral it gives Trichlorethidene-
diphenylamine, (CgH5.NH)jCH.CCl3, melting at 100°. Acrolein-aniline,
C8H5.N:CH.CH:CH2 (?), is amorphous and yields quinoline, C9H,N,upon distil-
lation.

DIPHENYLAMINE. 603

Diethylene-diphenyl-dia'mine, (CgHj.Nlj.rCH,),, or Diphenyl Pipera-
zine, CgH^.N^' prr^'pjj^i^N.CjHj, a derivative of piperazine, C^HijNj, is pro-
duced when aniline is heated with ethylene bromide and caustic potash, or so-
dium carbonate [Berichte, 22, 1387, 1778). It crystallizes from alcohol in needles
melting at 163°.

PHENYLATED PHENYLAMINES (p. 594).

Diphenylamine, (C6H5)2NH, is produced in the dry distilla-
tion of triphenyl rosaniline (Rosaniline blue), and is prepared by
heating aniline hydrochloride and aniline to 240° : —

CsH,.NH,.HCl + C.H^.NH, = (C,H,),NH + NH^Cl.

It results also upon heating aniline with phenol and ZnClj to 260°.
It is a pleasant-smelling, crystalline compound, melting at 54", and
boiling at 310° (corrected). It is almost insoluble in water, but
readily soluble in alcohol and ether. It is a very weak base, whose
salts are decomposed by water. Nitric acid or sulphuric acid, con-
taining nitrogen oxides, colors it a deep blue, and it serves in the
preparation of various dye-stuffs. The acridines are obtained when
diphenylamine is heated to 300° with fatty acids.

Methyl Diphenylamine (CgH5)2N.CH3, is formed by the action of methyl
chloride upon diphenylamine. It boils at 290-295° (282°). Diphenyl nitros-
amine, (CjHjjjN.NO, is produced when ethyl nitrate acts on diphenylamine, or
by the addition of HCl-diphenylamine to an acetic acid solution of potassium
nitrite. Yellow plates of great brilliancy, melting at 66.5°- It dissolves with a
deep blue color in concentrated sulphuric and hydrochloric acids. Alcoholic
hydrochloric acid changes it to/-Nitroso-diphenylamine, CgHs.NH.CjH^.NO
(p. 600), crystallizing in green plates, which melt at 143°. It splits up into
/-nitrosophenol, C5H4(NO).OH, and aniline when boiled with alkalies (Berichte,
20, 1252; 21, Ref. 227).

/-Nitrodiphenylamine, C5H4(N02).NH.C5H5, from benzoyl nitro-diphenyl-
amine, forms reddish-yellow needles, melting at 132°. o-Nitrodiphenylamine
results from aniline and (7-chlornitrobenzene. It crystallizes in leaflets melting at
T^° {^Berichte, 22, 903). /-Dinitrodiphenylamine, [CjH4(N02)]2NH, consists
of yellow needles with a blue schimmer, and melts at 214°.

Various Tri- and Tetranitro-diphenylamines are produced by the action of
chlor-dinitro- and trinitro-benzenes upon aniline and nitro-anilines. Hexanitro-
diphenylamine, [C5H2(N02)3]2NH, is formed by the direct nitration ot
diphenylamine and methyl diphenylamine. Yellow prisms melting at 238°
{Berichte, ig, 845). It dissolves with a purple-red color, in the alkalies, forming
sails. Its ammonium salt occurs in commerce as a brick -red powder, bearing the
name Aurantia ; it colors wool and silk a beautiful orange.

/-Amido-diphenylamine, CeH5.NH.C5H4(NH2), is formed by the reduc-
tion of its nitro- or nitroso-compound {Berichte, 23, Ref. 102), and also by the
decomposition of phenylamido-azobenzene and diphenylamidoazobenzene sulphonic
acid (tropseoline 00) (see azo-compounds). It consists of laminae melting at 61°.
/-Diamido-diphenylamine, [C5H4(NH2)]2NH, is obtained in the reduction of

6o4 ORGANIC CHEMISTRY.

the dinitro-compound, and by the decomposition of aniline black, and the reduc-
tion of phenylene blue with zinc dust and alkali. It crystallizes from water in
leaflets, melting at 158°. It forms quinone when oxidized; ferric chloride or
chromic acid colors it dark green. Its tetramethyl compound is formed by ths
reduction of dimethyl phenylene green.

Diamido-diphenylamine bears a close relation to the indamine- and indoaniline-
dyestuffs (see these).

Dimethyl-amido-dinitro-diphenylamine, NH^ r^u^'r-t^n \^ > ^ formed

from /-amido-dimethyl aniline and o/-dinitro-chlorbenzene. It forms bronze-
colored leaflets {Berichie, 23, 2739).

Oxy- and Dioxydiphenylamines are formed on heating anilines with dioxy-
benzenes (resorcin, hydroquinone) and CaClj to 250-270°; at higher temper-
atures, and with ZnCl2 we get diphenyl-phenylenediamines, CgH^(NH.CgH5)2.
{Berickte, 16, 2812). /-Oxydiphenylamine, from hydroquinone and aniline
{Berichie, 17, 2431), melts at 70° and distils about 340°. When heated with sul-
phur it yields oxythiodiphenylamine (see below) .

The oxydiphenylamines are closely allied to the indophenol dyestuffs.

Thiodiphenylamine, HN(^„^tt*^S, is produced on heating diphenylamine

with sulphur to 250° or with SClj [Berichte, 21, 2063). It crystallizes from alco-
hol in yellow laminae, melts at 180°, and boils near 370°. A purely synthetic
method for its preparation consists in heating »-amidotJiiophenol with pyrocatechol
to 220° : —

r H /^"3 _i_ "0\r H — r H /■'^"\(- h -u ^tt n-

it follows from this that the two phenylene groups occupy the two ortho positions
(Berichie, ig, 325^). It is neutral and does not combine with acids. Its imide
hydrogen can be replaced by alkyls and acid radicals {Berichie, 18, 1844). Fum-
ing nitric acid converts it into a dinitro-sulphoxide, HN(f „^tt'L^J^2)\sO.

Reduction changes this to diamido-thio-diphenylamine, HN(^ r'^Ti^/ivrH^I v)S>

which is also produced by heating /-diamido-diphenylamine (p. 603) with sulphur
(Berichie, 17, 2857). When this product is oxidized with ferric chloride, it yields
Lauth's violet, which may be again reduced to the diamido-compound.

A moderated nitration of thiodiphenylamine produces mononitrosulphoxide,

which is reduced to amidothiodiphenylamine, NH(^ ^ /^ ■ When

the latter is oxidized it yields a dyestuff' like the violet. Similarly, /-Oxydi-
phenylamine (above), when heated with Sulphur, forms an Oxythiodiphenyl-

amine, HN^ * ■* ^S , which may be oxidized to a dyestuff' (Berichie, 17,
2860). ^CgHj/OH

Triphenylamine, (C5H5)3N, is obtained on heating dipotassium aniline (p.
594) or sodium diphenylamine with brombenzene (Berichie, 18, 2156). It
crystalhzes from ether in large plates, melts at 127°, and distils undecomposed. It
dissolves in sulphuric acid, forming a violet, then a dark green color. It cannot
form salts with acids. By nitration it yields a trinitro-product that forms triamido-
iriphenylamine, 1^(0 ^^M'R^)^, by reduction (Berichie, 19, 759). Hexaphenyl-
rosaniline is produced when phosgene acts upon triphenylamine.

DIPHENYLAMINE DYES.

60S

Diphenylamine Dyes.

Thiodiphenylamine is a chromogen, i. e., a substance yielding colors, from
which leuco-compounds of dyestuifs are obtained by the entrance of NHj, NRj or
OH (see rosaniline). When the leucoderivatives are oxidized (split off 2H-atoms,
while at the same time 2N-atoms are combined) colors are produced, the salts of
which are the real dyes. These have been called Lauth's dyestuffs (Bernthsen,
Annalen, 230, 73; Berichte, 18, Ref. 705; Annalen 251, I ; Berichte, 22, 390).
The most important are : —

/NH,

HN(

^C„H„ .

^NH,

Leucothionine,

hn/

C„H„

V,H

/NH,
/

'\nh.hci

/N(CH3),
\n(CH3),

Leucomethylene
Blue.

N(CH3),

^C^H,

N,

C,H
C„H

/

N(CH3),.C1

HCl-Thionine.
Lauth's Violet.

Tetramethyl Thionine-hydrochloride,
Methylene Blue.

Lauth's violet (thionine) can be produced from thiodiphenylamine after the
manner above described. An easier course is that adopted by Lauth, viz., to
oxidize an HjS-solution of /-phenylenediamine, CgH^(NH2)2, with ferric
chloride. It is a direct color for silk and wool, but only attacks cotton after the
latter has been mordanted. Owing to its high price it has not been used to any
great extent.

Methylene blue,.discovered by Caro in 1877, is more important. It is formed by
oxidizing dimethyl-/-phenylenediamine, H2N.CgH4.N(CH3)j, with FeClj in the
presence of HjS. On adding sodium chloride and zinc chloride it is precipitated
as the ZnCIj-double salt. This is the methylene blue or fast blue found in
commerce. It dyes silk with ease, and also mordanted cotton. It is the most
stable cotton blue. By reduction it yields its leuco-base (the HCl-salt) CigH^g
l^^.'&ZX-ietramethyldiamido-thiodiphenylamine. This reacts with methyl iodide,
forming a methyl compound, which also results from diamido-thiodiphenylamine,
and in this way proves the connection between methylene blue and Lauth's violet.

Dimethyl- and diethyl thionine {Berichte, 20, 931) result from methyl- and
ethyl-paraphenylenediamiue by oxidation in the presence of HjS : —

.NH.CH3

/

I

Dimethylthionine.

Oxidation of amidothiodiphenylamine and oxythiodiphenylamine (p. 604) pro-
duces the compounds —

\CsH3< and ^C.H,/

^NH ^O

Imidothiodiphenylimide.

Oxythiodiphenylimide.

6o6 ORGANIC CHEMISTRY.

See Annalen, 230, 169 for additional analogous derivatives.
Phenazoxine, or phenoxazine, is a chromogen analogous to thiodiphenylamine.
It is obtained by* heating o-amidopbenol witli pyrocatecbol : —

C.H,/NH, ^ HO\c^H,= C,H /NH\c^H, + 2H,0.

Its nitro product, when reduced, yields a leuco-amide compound, which forms a
red-violet dye upon oxidation. Methylene red is a by-product in the preparation
of methylene blue {Annalen, 251, I ; Berichte, 22, Ref. 390).

ACID ANILIDES.

An atom of hydrogen of the amido- or imid-group in the pri-
mary and secondary anilines, can also be replaced by acid radicals.
The resulting compounds are termed anilides, and are formed
according to methods similar to those used with the acid amides of
the fatty series (p. 255) ; by the action of acid chlorides or acid
anhydrides upon the anilines, or by heating the organic salts of the
latter :—

CjHs.NHj.O.CO.CHj = C5H5NH.CO.CH3 + HjO.

Aniline Acetate. Acetanilide.

They are very stable derivatives ; can usually be distilled with-
out change, and also directly chlorinated, brominated and nitrated
(p. 596). They are resolved into their components by digesting
them with alkalies or heating with hydrochloric acid. The second-
ary anilides, like secondary alkylanilides (p. 594), yield nitrosa-
mines by the action of nitrous acid : —

c:h:o>NH + NO,H = ggo>N - NO -f H,0.

These give the nitrosamine reaction with phenol and sulphuric
acid ; but are less stable than the nitrosamines of the secondary
anilines. Reducing agents break off their nitroso-group.

Formanilide, CgH5.VH.CHO, is obtained on digesting aniline with formic
acid, or by rapidly heating it together with oxalic acid : —

C5H5.NH3 -I- CjOjHj = CgHj.NH.CHO + CO, -|- H,0.

It consists of prisms, readily soluble in water, alcohol and ether. It melts at 46°,
and continues liquid for some time. Concentrated sodium hydroxide precipitates

C H *v
the crystalline compound, nviA ^NNa, which is resolved by water into formani-
lide and NaOH. Silver nitrate added to the alcoholic solution of the sodium
compound, precipitates silver formanilide, C5H5.N:CH(OAg). When formani-

_ACID ANILIDES. 607

lide is distilled with concentrated hydrochloric acid, benzonitrile is produced
(small quantity) [Berickte, 18, looi) : —

CeH5.NH.CHO = C5H5.CN + HjO.

Dry HCl converts formanilide at 100° into diphenyl-methenylamidine (p. 621).
The alkyl formanilides, CgH5.NR{CH0), are produced when the alkyl iodides
act upon sodium formanilide, or upon formanilide with NaOH ( I molecule) in
alcoholic solution. They are odorless liquids which sustain a partial decomposition
when- distilled. They are resolved into acids and alkyl anilines when digested with
alcoholic potash or with hydrochloric acid (Berichte, 21, 1107). The alkyl
isoformanilides, CjHj.NiCH.OAg, compounds isomeric with the preceding, result
when the alkyl iodides act upon silver formanilide {^Berichte, 23, 2274, Ref. 659).
P2S5 changes formanilide to Thioformanilide, CgHj.NH.CHS, which consists of
white needles, melting at 137°, and decomposing at the same time into HjS and
phenylisocyanide, CgHj.NC. It is also formed when hydrogen sulphide acts upon
phenylisocyanide (p. 260), or diphenyl-methylamidine; aniline is produced at the
same time: C^Hs.N = CH — HN. CgHj + H^S = CsH^.NH.CHS + C^lly
NHj. Consult Berichte, 18, 2292, upon homologous thioformanilides.

Acetanilide, C5H5.NH.CO.CH3, is produced by boiling (equal molecules)
aniline and glacial acetic acid together for several hours {Berichte, 15, 1977) ; the
solid, crystalhne mass is then distilled. It melts at 114° and boils at 295°, with-
out decomposition. It is soluble in hot water, alcohol and ether. Sodium con-
verts it into sodium acetanilide, C5H5.N(Na).CjH30. Its hydrochloride is de-
composed by water into acetanilide and hydrochloric acid. When the salt is heated
to 250°,lt yields diphenyl ethenylamidine (p. 621), at 28o°,flavaniline,Ci5Hj4N2
and at 300°, dimethyl quinoline (Berichte, 18, 1340). ff-Amido-acetophenone,
C8H^(NHj)C0.CHg, is produced when aniline is boiled with acetic anhydride
and ZnClj. EthylaniUne, together with acetic acid, is the product on heating
acetanilide with sodium alcoholate (Berichte, ig, 1356) : —

C.Hj.NH.CO.CHg + CjHj.ONa = CeH5.NH.C2H5 + (CH3).C02Na.

/- and o-Di-substitution products (p. 596) are produced when chlorine, bromine
and nitric acid act upon acetanilide ; they yield mono-substituted anilines by
saponification. Monochloracetanilide (l, 4) melts at 162°, the dichlor (l, 2, 4) at
140°, and both are formed by the action of bleaching lime (acidified with acetic
acid) upon acetanilide. Monobrom-acetanilide (1,4) melts at 165°; the dibroin
(l, 2, 4) at 78°. p-Nitroacetanilideme\^ at 207° (Preparation, Berichte, 17, 222).

The isomeric bromacetanilide, CgHj.NH.CO.CH^.Br (melting at 131°), yields
indigo blue when it is fused with caustic potash. It is very probable that pseudo-

indoxyl, C6H4/^^>CH2,is first produced (Berichte, 23, 57).

Thioacetanilide, CeHj.NH.CS.CHj or C6H5.N:C('^^ (p. 260), is obtained

by heating acetanilide with phosphorus pentasulphide (Berichte, 19, 1071). It
crystallizes from water in needles, melting at 75°. It is soluble in alkalies, but is
separated again by acids. An alkaline solution of potassium ferricyanide oxidizes
it to elhenyl amido-thiophenol (Berichte, 19, 1072) : —

CeHjNH.CS.CHg-f 0 = CeH^<^^^C.CH3 + Yif).

The analogous compounds react similarly. ^/;4j//J0^<^ thioacetanilides, ir.^.,CgH5.
N(CH3).CS.CH3, are obtained from the acetyl compounds of the secondary ani-

6o8 ORGANIC CHEMISTRY.

lines (like acetmethyl-anilide (C6H5.N(CH3).CO.CH3), by heating them with
P2S5 [Berichte, 15, 528) : —

C6H5.N(CH3).CO.CH3 yields C6H5.N(CH3).CS.CH3.

Methyl-thioacetanilide, melts at 58-59°, and boils at 290°.

The derivatives of hypothetical isothioacetan.ilide,C^c,^:C{^-y!^ (p. 260),

are isomeric with the above. They are obtained by the action of sodium alcoholate
and alkyl iodides upon thioacetanilide (similar to formation of phenyl-isothio-ure-
thanes, p. 615, and of phenyl-isothio-.ureas, p. 617) : —

C,H,.NH.CS.CH3 + CH3I = C,H5.N:C^£^|j^ + HI.

M ethyl-isothio-acetanilide.

The methyl compound boils at 245°, the ethyl at 250°, These decompose into
aniline hydrochloride and thioacetic ester, CH3.CO.SR, when shaken with hydro-
chloric acid.

ANILIDO-ACIDS.— PHENYLAMIDOACIDS.

Anilido-formic Acid, CgHj.NH.COjHjis carbanilic acid (p. 612).

Anilido-acetic Acid, CgHj.NH.CHj.COjH, Phenyl- glycocoll, Phenylgly-
cin, is obtained from chlor- or brom-acetic acid by the action of aniline (2 molecules)
and water (Berichte, 10, 2046; see, also, Berichte, 21, Ref. 136). It forms
indistinct crystals, melting at 127°.

Its alkyl esters are produced when aniline is heated with the diazo-acetic esters
(p. 374). If the free acid be heated to r40-l5o°, it passes into the anhydride
(CgHj.N.CHj.COjj, which is insoluble in water, and melts at 263°.

It is identical with diphenyldiacipiperazine [Berichte, 22, 1786, 1795) : —

.CO.CHj
C,H,.N( >N.CeH3

^CHj.CO

Indigo blue results upon fusing a mixture of phenylglycin and caustic potash

. CO
with air access. It is very probable that pseudoindoxyl, CgH^^^ >CHj, is

formed at first, but is then oxidized to indigo {Berichte, 23, 3044).

Nitrous acid converts phenylglycin intoNitroso-phenylglycin, CgH5.N(N0).
CHj.COjH. This may be reduced to an amido-compound, identical with the ^he-
nylhydrazone of glyoxylic acid, C6H5.NH.N:CH.C02H (p. 330).

CHj.CO
Phenylhydantoin, CjHj.N, >, results upon heating phenylglycin

^CO.NH
and urea to ioo°- It forms delicate needles, melting at 191°. a-Phenylhydan-

.CO.NH
toin, CgHj.CH^ >, is isomeric with the preceding. It may be obtained

^NH.CO
from benzaldehyde-cyanhydrin and urea (p. 392). It melts at 178° [Berichte, 21,
2321).

ANILIDO-ACIDS. 609

Indol, results upon distilling a mixture of the calcium salt of phenylglycocoU
and calcium formate {Berichte, 22, Ref. 579). In the same manner, c-tolindol is
obtained from ff-tolylglycocoU {Berichte, 23, Ref. 654).

o-Nitrophenyl GlycocoU, C6H4(N02).NH.CHj.C02H, formed by heating
o-nitraniline with bromacetic acid to 130°, crystallizes in dark red prisms, melting
at 193°- When it is reduced by tin and hydrochloric acid, it forms an amido-
derivative. The latter condenses to oxy-dihydroquinoxaline, with separation of
water (Berichte, 19, 7) : —

C«H / = C,H / I + H,0.

OH

The higher anilido-fatty acids are similarly prepared from aniline and the brom-
fatty acids. They can (their nitriles) also be formed from the cyanhydrins of the alde-
hydes by digesting them with aniline. Thus, ethidene cyanhydrin yields a nitrite,
that upon saponification with hydrochloric acid becomes a-anilido-propionic acid
(Berichte, 15, 2034) : —

.CN .CN yCOjH

CH3.CH<; yields CHj.CH^ and CH..CH<f

^OH \NH.CeH5 ^NH.C^H^.

The esters of the anilido-fatty acids are produced by heating diazo-fatty acid
esters with aniline (p. 374) : —

C5H5.NH2 -f CH(N2).C02R = CjH5.NH.CH2.CO2R -f Nj.

a-Anilido-propionic Acid, Phenylalanine, consists of colorless laminae, melt
ing at 162°. They turn red on exposure to the air.

Anil-pyroracemic Acid, C8H5.N:C(CH3).C02H, is formed from pyro-racemic
acid and aniline (2 molecules). Boiling water converts it into anil-uvitonic acid,
CjjHgNOj, a derivative of quinoline, which yields methyl-quinoline, C9Hg(CH3)N,
when distilled with lime (Berichte, 16, 2359).

By heating aniline and aceto-acetic ester to 120-135° Acetoacetanilide,

CHj/^QS-^aj-, jj , is produced. It melts at 85° (Annakn, 236, 75). When

warmed with sulphuric acid it splits off water and condenses to y- methyl carbostyril
(Berichte, 21, 625).

When aniline and aceto-acetic ester interact at the ordinary temperature there
is formed anil-aceto-acetic ester, that may be considered as /3-Phenyliinido-
crotonic Ester, CH3.C(NH.CjH5)-,CH.COj.R (p. 339), or ^-Phenylamido-

crotonic Ester, CjHs NH.C^^^jj'^^ ^ (Berichte, 20, 1397; 21, 1965). This

is a thick oil. Acids and alkalies decompose it into its components. If it is
heated to 200° it loses alcohol and condenses to y-oxyquinaldine, CijHgNO, and
phenyl lutidon-carboxylic acid, CjjHjjNOj (^^^-zV^i/^, 20, 947 and 1398). ^ The
latter is also formed on heating with methyl iodide (Berichte, 22, 83).

Toluidines, etc., react in a similar manner with aceto-acetic esters. The products
are tolylamidocrotonic esters, etc., which by condensation form y-oxyquinaldine
derivatives (Berichte, 21, 523).

C5H5.NH.C(CH3).C02H,

3-Anilidp-pyrotartaric Acid, | is formed when prus-

CHJ.CO2H
sic acid and aniline act upon aceto-acetic ester (Berichte, 23, 893). It melts at
102°, and when heated to 180° yields citraconanile (p. 611, see Berichte, 23, 542).

SI

6lO ORGANIC CHEMISTRY.

ANILIDES OF DIBASIC ACIDS.

Oxanilide, C202<;^^^'^6^=, diphenyl-oxamide, is obtained by heating ani-
line (2 molecules) with oxalic acid (l molecule) to i8o°. It consists of pearly
leaflets, melting at 245° and boiling near 360°. It dissolves readily in benzene,
but with difficulty in hot alcohol.

Oxanilic Acid, CjOj^' (-vrj' ' s^ jj formed by heating aniline with excess of

oxalic acid to 140° [JBerichte, 23, 1820). It crystallizes in leaflets, dissolves in
water, reacts acid, and conducts itself like a monobasic acid.

/-Nitro-oxanilic Acid, C5H4(N02).NH.CO.C02H (with some ortho-product),
is obtained by nitrating oxanilic acid. It melts at 210°. o-Nitro-oxanilic Acid
is more easily obtained by fusing a mixture of o-nitraniline and oxalic acid at 140°.
It crystallizes in yellow needles and melts at 120° (Berichte, 19, 2936). Tin and
hydrochloric acid reduce it to a-Amido-oxanilic Acid, which loses water and
immediately condenses to dioxyquinox aline : —

.NH.CO.COjH ,NH.CO

C,H / = C,H / y -f H^O.

^NH^ ^NH.CC)

In a similar manner nitro-oxalyl toluidic acid (from nitrotoluidine and oxalic
acid), C5H3(CH3)/^J^-*^^-^^2^, yields dioxymethylquinoxaline {Berichte, 17,

318; 19, 671).

The anilides of the higher di- and poly-basic acids may be easily prepared by
heating their anhydrides with aniline. PCI5 converts them into acid aniles
{Berichte, 21, 957) : —

CO.NH.C5H5 .CO. .CO.NH.CjHj

C2H,( C^H / )n.C,H, C^H /

Succinanilic Acid. Succinanile. Succinanilide.

Malonanilic Acid, CH2<[^pq'ti ' * ^^ jj produced by a peculiar transposi-
tion of acetylphenyl carbaminate of sodium when heated to 140° {Berichte 18,

1359) :—

.CO.CH3
CgH^.N/ = C5H5.NH.CO.CH,.C02Na.

^CO^Na

The acid crystallizes in needles, melting at 132° and decomposing into CO2 and
acetanilide. PCI5 converts it into trichlorquinoline {Berichte, 17, 740 ; 18, 2975).
Malonic acid and toluidine yield malon-toluidic acid, from which trichlormethyl-
quinoline may be obtained {Berichte, 18, 2979).

Succinanilic Acid melts at 148°. When heated higher it decomposes into
water and Succinanile, CjH4(CO)2.N.C5H5, melting at 150°, and boiling at
400°.

Maleinanilide, C2H2(CO.NH.C|5H5)2, results upon digesting maleic acid
with aniline. It melts at 2U°. Fumaranilide, C2H2(CO.NH.CjHg)2, is pro-
duced when aniline is heated together with malic acid. It melts at 87°.

ANILIDES OF CARBONIC ACID. 6ll

Citraconanile, C^H402:N.C5H5, from citraconic and mesaconic acids with
aniline, is also formed in the distillation of anilido-pyrotartaric acid (p. 609). It
melft at 96° {Berichte, 23, 891).

Phthalanile, CsH4^(CO)2N.CgH5, from aniline and phthalic acid, melts at
205°. It is used in effecting different syntheses.

ANILIDES OF CARBONIC ACID.

Diphenyl urea, CO^ NH C^H^' carbanilide, is formed by the action of
phosgene gas on aniline {Berichte, 16, 2301) : —

COCI2 + 2C5H5.NH2 = CO(NH.C8H5)2 + 2HCI;

by the union of carbanile (p. 612) with aniline : —

CO:N.C,H, + NH,.CeH, = COlNH.CeH^), ;

by the action of mercuric oxide or alcoholic KOH upon diphenyl thio-urea
(p. 6i6) :-

CS(NH.C,H,), + HgO = C0(NH.C,H5), + HgS;

and by heating aniline (3 parts) with urea (l part) to 150-180° : —

COCNH^), + 2NH2.CeH5 = COCNH.C.H^), + 2NH3.

It is most readily obtained by heating carbanilamide with aniline to 190° (Berichte,
g, 820), or by heating diphenyl carbonate with aniline to 150-180° (Berichte 18,
516):-

CO(O.C,H5), + 2NH,.CeH, = CO(NH.C,H5), + 2C,H,.0H.

Carbanilide consists of silky needles, easily soluble in alcohol and ether, but
sparingly soluble in water. It melts at 235° and distils at 260°. When boiled
with alkalies it decomposes into aniline and urea. Triphenyl-guanidine is pro-
duced on heating it with sodium ethylate to 220° (Berichte, 16, 2301).

Diphenyl Urea Chlorides (p. 376) (Berichte, 23, 424), are produced when
COCI2 acts upon secondary anilines, such as diphenylamine : —

COCl2+NH(CsH5)2 = C0/q(^6H5)2 ^ ^Cl.

Diphenyl urea Chloride, (CgHj), N.COCI, crystallizes in white laminse, melt-
ing at 85°. When these urea chlorides act upon benzene in the presence of AICI3
they form the diphenylamides of aromatic acids —

• (C,H,)2N.C0C1 + C,He = (Q.,'R^)^^.CO.C,-R^ + HCI,

which pass into acids and diphenylamine on warming with hydrochloric acid
(synthesis of aromatic acids, Berichte, 20, 21 18). Thiophosgene acts like COCl,.
It converts the secondary anilines into Thiourea chlorides, e.g.,(Q!^^,^.Q,^C\,

and Thiocarbanilides, c. g., CS<^^|^«|| y {Berichte, 21, 102). Diphenyl urea

chloride heated to 100°, with alcoholic ammonia, yields unsymmetrical diphenyl

6l2 ORGANIC CHEMISTRY.

urea, CO^iTW"^^". I^ng needles, melting at 189°, and when distilled

yielding diphenylamine and cyanic acid. If the chloride be heated with aniline

we get Triphenyl urea, CO('j^|j^ j^'' . It is also produced by mixing

phenylisocyanate with diphenylamine. It crystallizes in needles, melting at 136°.
Mixed phenyl ureas are obtained in the same manner (^Berichte, 17, 2092). The
action of diphenylamine upon diphenyl urea chloride produces tetraphenyl urea,

CO (f Sir ^S^^- Crystals melting at 183°.

Phenylurea, CO (^^Jf^^ S Carbanilamide, is obtained like the alkylic
ureas (p. 388) : by conducting vapors of cyanic acid into aniline; CO:NH -j- Cj
H5.NH2 = CO^ ^tt' ^ * ; and by the action of ammonia upon carbanile : —

CO:N.C,H, + NH3 = C0/^g-^^«^^

It is best prepared by eyaporating the aqueous solution of aniline hydrochloride
and potassium isocyanide (Berichte, 9, 820). It forms needles easily soluble in
hot water, alcohol and ether and melting at 144-145°- If boiled with caustic
potash it breaks up into aniline, ammonia and cyanur'ic acid.

Esters of isocyanic acid convert aniline into alkylized phenyl ureas, e. g.,

*-^°\NH C^H^' ^''•y' phenylurea.

■ ' ' N(CeH,).CH,
Glycolyl-phenylurea, C0(^ , phenyl-hydantoin (p. 392), is

\nh CO

obtained on heating phenylglycocoU (p. 608) to 160° with urea. It consists of
needles, melting at 191°.

Carbanilic Acid, CO^' fvtr' ^ ^, phenyl carbatnic acid, is not known in

a free state. Its esters, called phenyl urethanes, (p. 383) result in the action of
chlorcarbonic esters upon aniline (most easily by shaking the two compounds with
water {^Berichie, 18, 978), or of carbanile upon alcohols and phenols: —

CO:NCeH, + C,H,.OH = Co/^H.^CeH,

The ethyl ester melts at 52° and boils at 237°, decomposing partially into CO:N.
C5H5 and C2H5.OH, which reunite on standing. Diphenylurea is formed on
heating with potash or with aniline. The methyl ester melts at 47°, and is con-
verted into amidosulphobenzoic ester when dissolved in sulphuric acid {Berichte,
18, 980) :—

CeH,.NH.C02.CH3 + SO^H, = C,H J SO3H + H,0.

ICO.CH,

The //5if»y/ w^^r, CgH5.NH.CO2.C5Hg, is formed when carbanile is heated,
with phenol (readily in the presence of AlCl,). It melts at 124° {Berichte, 18,

875)-

Carbanile,'CO:N.C3H5, phenyl isocyanate, is produced in the distillation of
oxanilide, or better oxanilic esters with PjOj, also from diazobenzene salts,
CgHj.NjX, by the action of potassium cyanate and copper (Berichte, 23, 1225).
It may be most readily obtained by leading COClj into fused aniline hydrochloride

ANILIDES OF CARBONIC ACID. 613

[Berichte, 17, 1284), or by heating phenyl mustard oil to 170° with HgO {^Be-
richte, 23, 1536). It is a mobile liquid, boiling at 163° and has a pungent odor,
provoking tears. Carbanile is perfectly analogous to the isocyanic esters in
chemical deportment (p. 274). It yields diphenylurea with water. With ammonia

carbanilamide, CO^ jjtt" ° *, is formed ; with the apiines we obtain correspond-
ing alkyl compounds.

It unites with polyhydric alcohols and phenols to form carbanilic esters. This is
a reaction that can be employed in determining alcoholic hydroxyls (Berichte, 18,
2428 and 2606).

Phenylisocyanate acts in a similar manner upon aldoximes and ketoximes (p.
205). The hydrogen of its hydroxyl group is replaced {Berichte, 22, 3101,3109;
23, 2163) :—

C6H5.CH:N.OH + CON.CjHj = CeH^.CHiN.O.CO.NH.CsHs.

However, carbonyl compounds (with the group CO) do not react with phenyl-
isocyanate. The reaction, therefore, can be employed for the purpose of deter-
mining constitution (Berichte, 23, 257).

Phenylisocyanate also reacts with the sulphydrate group SH ; the CS-group is
without action (Berichte, 23, 272).

Diazo-amido-compounds, e.g., C5H5.Nj.NHR, react with phenylisocyanate.
In so doing, the hydrogen of the amido-group is replaced (Berichte, 22, 3109).

The preceding reactions, occurring in the absence of water (thus avoiding elec-
trolytic dissociation), proceed in the normal way. Rearrangements do not take
place, hence they are well adapted for the determination of constitution (Gold-
schmidt, Berichte, 23, 2179).

On heating phenylisocyanate with benzene and AICI3, we get benzoylanilides: —

C^H^.NiCO + C^H, = C5H3.NH.CO.CeH5.

Phenylisocyanate can be polymerized by heating it with potassium acetate (Be-
richte, 18, 764), when there is formed

Triphenylisocyanurate, (CON)3(C5H5)3 (p. 276). Itis also obtained upon
heating triphenylisomelamine (p. 620) with concentrated hydrochloric acid to 150°
C. (Berichte, 18, 3225) : —

,C3N3(C5H5)3(NH)3 -f 3HP = C303N3(C5H5)3 + 3NH3.

It crystallizes from alcohol in white needles, melting at 275°. Its isomeride is

Triphenylcyanurate, CjNjfO.CgHjjj. The action of cyanogen chloride or
cyanuric chloride upon sodium phenate, produces this : —

3C5H5.0.Na + C3N3CI3 = C3N3(0.C5H5)3 -f 3NaCl.

It crystallizes in long needles, melting at 224°.

Phenyl Isocyanide, C5H5.NC, phenyl carbylamine, is isomeric with ben-
zonitrile, CeH5.CN (p. 287), and is produced by the action of chloroform on
aniline in an alcoholic solution of KOH (Berichte, 10, 1096), or by the distillation
of diphenyl-methenyl-amidine (p. 621), and of thioformanilide, C3H5.NH.CSH.
It is a liquid, resembling prussic acid, with pungent odor and boiling at 167° with
partial decomposition. ItiSi ^^oic, being blue in reflected and green in trans-
mitted light. Alkalies do not aSect it, but acids convert it into aniline and formic
acid. Heated to 220°, it passes into isomeric benzonitrile, CgH5.CN. It combines
with HjS, forming thioformanilide (p. 607).

6l4 ORGANIC CHEMISTRY.

Phenyl Mustard Oil, Sulpho-carbanile, CSiN.CsHj (p. 280), is obtained
by boiling diphenyl thio-urea (p. 616) with sulphuric or concentrated hydrochloric
acid, or, what would be best, with a concentrated phosphoric acid solution (Be-
richte, 15, 986) : — .

CS\NH:§H3 = CS:N.CeH5 + NH,.C,H, ;

and by the action of an alcoholic iodine solution (with triphenyl guanidine, Berichte,
9, 812), or CSCI2, upon aniline. It is a colorless liquid, with an odor resembling
that of mustard oil, and boils at 222°. It is converted into benzonitrile when
heated with reduced copper or zinc- dust : —

C^Hg.NiCS + Cu = CjHj.CN + CuS.

On this reaction is founded a procedure to replace the group NH^by COOH, that
is, to convert the anilines successively into thio-ureas, mustard oils, nitriles and
acids. Benzonitrile (with aniline) is also produced by directly heating diphenyl
thio-urea with zinc dust (^Berichte, 15, 2505).

In all its reactions, it is analogous to the mustard oils of the fatty series. If
heated with anhydrous alcohols to 120°, or by the action of alcoholic potash, it is
converted into phenyl-thio-urethanes (p. 386) : —

CS:N.C,H, -f C,H,.OH = Cs/^^■g«^^^

It forms phenyl-thio-ureas with ammonia, the amines and the anilines.

Phenyl-sulphocyanate, CgHj.S.CN, is isomeric with phenyl mustard oil.
It is formed when hydrosulphocyanic acid acts upon diazobenzene sulphate (see
this), and cyanogen chloride upon the lead salt of methyl mercaptan : —

(CeH5.S)2Pb + 2CNCI =2C5H5.S.CN + PbCIj.

It is a colorless liquid, boiling at 231°, and in its reactions is analogous to the sul-
phocyanic esters (p. 280).

Methenyl-amido Thiophenol, C^H^/^^^CH, derived from ortho-amido thio-

phenol, CgH^^^TT , is a base, and is isomeric with phenyl sulphocyanate and
phenyl mustard oils. See Amido-phenols.

Derivatives of Dithiocarbamic Acid (p. 386).

Phenyl Dithiocarbamic Acid, CS^ott ^^ ^' Its potassium salt is formed

when potassium xanthate (p. 381) is boiled with aniline and alcohol. It consists
of golden yellow needles. When the acid is liberated from its salts it decomposes
into aniline and CSj. Its esters — the normal dithio-urethanes (p. 386 and Berichte,
15, 563) — are produced by warming phenyl mustard oil with mercaptans : —

CeH5.N:CS + CH3.SH = CjHs.NH.CS.S.CHj;

and from the alkyl compounds of diphenyl isothio urea when heated with CSj (p.
617). The methyl ester melts at 87-88° ; the ethyl (Phenyl dithio-urethane) at
60°.

ANILIDES OF CARBONIC ACID. 615

When these dithio-urethanes are heated they decompose into phenyl mustard
oil and mercaptans. They dissolve in alkalies, and on warming part with mer-
captans [Berichte, 15, 1305). Completely alkylized dithio-urethanes, having the
imide hydrogen replaced by alkyls, are formed the same as the mono-alkyl deriva-
tives, i. e., by heating alkylized diphenyl-amidine-thioalkyls (p. 617) to 150° with,

CSj. Ethyl Phenyldithiourethane, CS(f?i???5)-*-'6^^ melts at 68.5°, and

boils at 310°. These compounds are very stable, no longer soluble in alkalies,
and are not desulphurized by mercuric oxide or an alkaline lead solution. They
form so-called addition products {Berichte, 15, 568 and 1308) with methyl iodide.
Phenyl sulphurethane and diphenyl-thio-urea (p. 6i8) do the same.

An analogous compound is formed on Ideating diphenylamidin-thio-ethylene (p.
618) with CS2. The product is called Ethylene- Phenyl-dithiocarbamate,

CS( \ {Berichte, 15, 345). ^-"^

^ S-C3H,

Derivatives of Sulphocarbamic Acid, CS(' r\\(^t thio-carbaminic acid,
CO^ qti 'j ^nd the hypothetical imidothiocarbonic acid, NH;C/^ nrr (p- 384).

Ethyl Phenylsulphocarbamate, Phenyl-thiourethane, CS^'q „■ r| ^

(Phenyl xanthamide) (Berichte, 15, 1307), is formed by heating phenyl-mustard-
oil with alcohol [Berichte, 15, 2164) : —

CgHj.NiCS + C2H5.OH = C6H5.NH.CS.O.C2H5.

It melts at 71-72°, and is resolved into phenyl-mustard-oil and alcohol when dis-
tilled. It is soluble in alkalies, and unites with mercury, silver and lead.

When alkyl iodides act upon these metallic compounds (not the free phenyl-
sulphurethanes) we obtain phenyl-isothiourethanes, the alkyl derivatives of phenyl
imido thio-carbonic acid (see above). The reaction is very probably analogous
to that occurring with thioacetanilides (p. 607) and the phenyl sulpho-ureas
(p. 617) :—

C,H,.NK.CS.O.C,H5-f CH3I = CeH,.N:C/°;^^^^= -f KI.

The methyl derivative is a liquid, and boils with partial decomposition at 260°-
The ethyl compound melts at 30° and boils at 278-280°.

These alkyl derivatives are soluble in concentrated hydrochloric acid, and are
precipitated by water. When heated with hydrochloric acid, they revert again to
phenyl sulphurethane and alkyl chlorides ; heated with dilute sulphuric acid to

200°, aniline and thiocarbonic esters, e.g., CO<^g'(-,|j *, result.

On oxidizing phenylsulphurethane, in alkaline solution, with ferricyanide ot
potassium, so-called ethoxyyphenyl mustard oil — a derivativeof o- amido-thiophenol
(see this) {Berichte, 19, 1811), is formed : —

C,H,.N:C/°^A + o = CeH,^^^C0.C,H3 + H,0.

The esters oi phenylthiocarbaminic acid (see above) e.g., C^O\gcH ° ^'
are obtained by heating the thio- alkyl-diphenylamidines (p. 617) with dilute sul-
phuric acid to 180° {Berichte, 15, 339).

6l6 ORGANIC CHEMISTRY.

The methyl ester melts at 83-84°; the ethyl ester at 73°- Warm alkalies
resolve them into aniline, carbon dioxide and mercaptans.

Another derivative of phenyl thio-carbaminic acid is the so-called glycolide
N(CeH5).C0
of Phenyl-mustard-oil, COf | (p. 398), which is formed by heating

\S CH^

phenyl-mustard-oil or phenyl-thio-urethane with chloracetic acid and alcohol to
160°; also by boiling diphenylthiohydantoin and (ortho) phenylthiohydantoin
(p. 618) with hydrochloric acid (Berichte, 14, 1663). It crystallizes from water
in laminae, melting at 148° and decomposing, on boiling with baryta, into aniline,
carbon dioxide and thioglycoUic acid.

Phenylthiurea, CS^ ^tt' * ^, Sulphocarbanilamide (p. 395), is formed by
the union of phenyl-mustard-oil with ammonia : —

CS:N.C,H, + NH3 = Cs/^H.CeH,_

It crystallizes in needles, melting at 154°, and forms a double salt with PtCl^.
S is replaced by O and phenylurea formed on boiling with silver nitrate.

Diphenyl-thiurea, CS;f TvifrV-^Tj^j sulphocarbanilide, is produced by the

union of phenyl-mustard-oil with aniline in an alcoholic solution : —

CSiN.CeHj -f NH^.C^H^ = Cs/nH^H; '

it is also obtained by boiling aniline (l molecule) with CSj and alcoholic potash
(l molecule) : —

CS, + 2NH,.C,H, = CSCNH.CeHj), + SH,;

the product is poured into dilute hydrochloric acid, the alcohol evaporated and
the mass crystallized from alcohol.

Diphenylthiurea consists of colorless, shining leaflets, melting at 151° [Berichte,
19, 1821), and readily soluble in alcohol. An alcoholic iodine solution converts
it into sulpho-carbanile and triphenyl-guanidine. When boiled with concentrated
hydrochloric acid or phosphoric acid, it decomposes into phenyl-mustard-oil and
aniline (p. 614) ; the mixed thiureas, containing two dissimilar benzene residues
and resulting from the phenyl-mustard-oils and anilines (see above), undergo,
under like treatment, a decomposition into two mustard-oils and two anilines
{Berichte, 16, 2016).

S is replaced by O, and the product is diphenylurea, if diphenyl thiurea be
boiled with alcoholic soda or mercuric oxide (p. 611); monophenyl thiurea, on
the contrary, has hydrogen sulphide removed and becomes phenylcyanamide
(P- 395)- i° '^ benzene solution mercuric oxide produces carbodiphenyhmide
(p. 620).

In the action of alcoholic ammonia and lead oxide NH replaces S, forming
diphenyl-guanidine (p. 395) : —

under like circumstances triphenyl-guanidines are formed with anilines.

ANILIDES OF CARBONIC ACID, 617

Phenyl- and diphenyl-thiurea are soluble in alkalies, because metallic com-
pounds are probably formed by the replacement of hydrogen of the imide-group
(as in the case of thioacetanihde, C5H5.NH.CS.CH3 p. 607). If this be true they
have not yet been isolated. Acids again set free the phenylureas.

See Berichte, 17, 2088 and 3033 upon the alkyl phenyl thiureas and triphenyl
thiureas. When the phenylthiureas are heated with amines secondary amine
residues are displaced by primary amine residues (^Berichte, 17, 3044).

Tetraphenylthiurea, CS;f t.t)^«tt^<', is obtained by heating] symmetrical

tetra-phenylguanidine (p. 619) with carbon disulphidd. It crystallizes in long,
shining needles, which melt at 195° {^Berichte, 15, 1530).

Derivatives of hypothetical Isothiourea, ^^Tr^JjiCSH (Imidothiocarbaihic acid,

amidine thiohydryl, p. 394, Berichte, 21, i860).

The diphenyl ihioalkyl derivatives (their haloid salts) are obtained by the action
of caustic alkali and alkyl iodides upon diphenylthiurea, or better by heating the
latter with an alcoholic solution of the alkyl iodides (bromides) (Berichte, 14,
1489 and 17SS; 21, 963; Annalen, 211, 85) : —

Diphenylthiurea. Diphenylamidine-thiethyl Derivative.

Alkalies set free the bases, which are soluble in alcohol and combine with I
equivalent of acid to form crystalline salts.

The methyl compound {J)iphenylamidine-Thiomethyt) melts at no"; the
ethyl derivative at 73°. If heated with alcoholic potash it splits up into diphenyl-
urea and potassium mercaptide : —

""bX-N/^-^-^'^^ + ^°'^ = C:h:.NH>CO + CA.sk ;

and when heated to 120° with alcoholic ammonia diphenyl-guanidine (p. 619)
and mercaptan are obtained : —

^cJCn^^-^-<^»^5 + NH3 = ^^cr^N)^-^^^ + C2H5.SH.

The alkyl derivatives yield carbodiphenylimide r^jj' N^^ ^P" ^^°^' ^°^ ™^'^"

captan when distilled; and when heated to 180°, with dilute sulphuric acid, they
decompose into phenylthiocarbamic esters (p. 615), and aniline : —

^if |i^^);C.S.CH3 + H,0 = C.H^.NH.CaS.CH, + C.H^.NH,.

If heated with carbon disulphide to 160° the products are phenyl-mustard oil, and
phenyl-dithiocarbamic esters {Berichte, 15, 338) :—

^«(f |f^)c.S.CH3 + CS, = CeH,.NH.CS.S.CH3 + CeH^.NiCS.

52

6l8 ORGANIC CHEMISTRY.

The last two decompositions are perfectly analogous to those of the amidines
(p. 293).

When the diphenylamidinethioalkyls are heated with allcyl iodides, their alkyl
derivatives result, <;.^.,'^«^6-N(CH3)\(,g^^jj^ ^^^^^ yield dialkylic dithio-

urethanes with carbon disulphide (p. 615).

Diphenylthiurea also reacts with benzyl chloride, C5H5.CH2CI. Ethylene

CeH^.N-C^H^
bromide forms Diphenylamidine-thioethylene, \ "), which car-

CeH5.N=C.S /
bon disulphide converts into elhylene-phenyl-dithiocarbaminate (p. 615). These
compounds contain the " five-membered " thiazole ring, hence they may be included
among the thiazole (p. 554) derivatives (Berickte, 21, 1871).

Chloracetic acid converts diphenylthiurea [Annalen, 207, 128) into: —

CeHj.NHX CgH^.N^- CO

C.S.CH2.CO2H and \ I .

CeH^.N^i^ CsH5.N<^ C.S.CHj

Diphenyl-thiohydantoic Acid. Diphenyl-thiobydantoifn,

the diphenyl derivatives of so-called thiohydantoin and thiohydantoic acid
(p. 397).

DiphenyUhiohydantoin, CuHj^NgSO (Diphenylamidine-thioglycollide),
crystallizes from alcohol in leaflets, and melts at 1 76°. It decomposes, like the alkyl
compounds (p. 617), when boiled with alcoholic potash, into diphenylurea, and
thioglycoUic acid, HS.CH^.COjH. Boiling hydrochloric acid decomposes it into

so-called glycolide of phenyl-mustard-oil, C5H5.N (^^q g-prj (p. 616), and
aniline. tt -vr^ \ • ■ 2

Phenylthiohydantoic Acid, ^ ^2^^C.S.CH2.C02H(Phenylamidine-thio-

glycoUic acid), is produced (analogous to the formation of amidines from amines
and cyanalkyls, p. 293) from aniline and sulphocyariacetic acid (or chlor-acetic
acid and ammoniura-sulphocyanate) {Berichte, 14, 732) : —

CeH,.NH, + CN.S.CH,.CO,H = CeH5.N:C/^^^^ CO,H.

It is soluble in alcohol, crystallizes in needles, and melts at 148-152°. Boiling
dilute sulphuric acid decomposes it into phenylurea and thioglycoUic acid.

Isomeric, so-called (ortho)-Phenylthiohydantoic Acid, CgHjoNjSOj, is
formed (analogous to thiohydantoic acid (p. 397) from phenyl-thiourea and
ammonium chlor-acetate (Berichte, 14, 1660) : —

C.H^ jIh/^S + CH^Cr.CO.H = (^^jj^^Jg^CS.CH.CO^H + HCl.
It is an amorphous mass, dissolving readily in alkalie s and acids. The withdrawal of

water from it yields so-called (ortho)-PhenyUhiohydantoin, / I

C,H,.N CO

GUANIDINE DERIVATIVES. 619

which melts at 178°, and is obtained from thio-urea and chloracet-anilide, CjHg.
NH.CO.CH2CI. Boihng dilute hydrochloric acid converts it into the glycolide of
phenyl-mustard oil (p. 616) ; ammonia is liberated simultaneously.

The real Phenylsulphydantoins, corresponding to hydantotn in constitution,
and isomeric with the preceding so-called phenyllhiohydantoins (more correctly
phenylamidine derivatives), are obtained by heating phenyl-mustard oil with
glycccoU (amido-fatty acids) [Berichte, 17, 424) : —

CS:N.C,H, + NH,.CH,CO,H = Cs/^^C^g^)\^ + H,0.

Phenyls ulphydantoin.

They are converted into the corresponding phenylsulphydantoic acids on boiling
with alcoholic potash, and are desulphurized by boiling with lead oxide.

GUANIDINE DERIVATIVES (compare p. 294).

Diphenyl-guanidine, HN:C<^„tt'„^tt^ (Melaniline), is produced by the

action of CNCl upon dry aniline, and by digesting cyananilide, CgHj.NH.CN,
with aniline hydrochloride. It crystallizes in long needles, melting at 147°- It
is a mono-acid base, forming crystalline salts. CS2 transforms it into sulpho-car-
banilide and sulphocyanic acid, which combines with a second molecule of
diphenyl-guanidine : —

Tvrtr.f /NH.CgHj I po — pq/NH.CjHj . „-.„„
■^"•"-XNH.CeHj +^^2 — "-'^xNH.CeHj + ^JM!5tt-

a-Triphenyl-guanidine, CjHj.NiC/ -j^ttV^tt', is obtained on heating di-

phenyl-urea and diphenyl-thiurea, alone or with reduced copper, to 140°. It is
most readily prepared by digesting diphenyl-thiurea and aniline, with litharge or
mercuric oxide (or by boiling with an iodine solution) : —

^^XNH.CjHs + JMW2-^6"5 — '-6"s-J>l-"-\NH.CjH5 + ^"a-

Triphenyl-guanidine crystallizes in rhombic prisms, melts at 143°, and is insolu-
ble in water, sparingly soluble in ether, but readily in alcohol. It is a monacid
base, and yields well crystallized salts. Heated with CSj, it reverts again to
diphenyl-thiurea and phenyl mustard oil.

Isomeric j8-Triphenyl-guanidine is obtained by heating cyananilide with HCl-
diphenylamine : —

/N(CeH,),
C.H^.NH.CN + NH(C6H,)2 = C=NH

\NH.CeH5

It crystallizes in large plates, melting at 131° (see Annalen, 192, 9). It decom-
poses into diphenylamine, phenyl mustard-oil, and sulphocyanic acid when heated
with carbon disulphide.

620 ORGANIC CHEMISTRY.

Symmetrical Tetraphenyl-guanidine, NH:C<fjjV(-,«jj5)2^is produced by the

action of CNCl upon diphenylamine at 170°. Its crystals are insoluble in water,
and melt at 130°.

CYANAMIDE DERIVATIVES (p. 289).

Cyananilide, C5N5.NH.CN, phenyl cyanamide (p. 289), is formed on con-
ducting CNCI into a cooled ethereal solution of aniline, and by digesting phenyl-
thiurea with litharge, or by heating it with lead acetate and alkali (Berickte,
18, 3220). It is readily soluble in alcohol and ether, but dissolves with difficulty
in water. It contains ^ molecule of water of crystallization. It forms needles,
melting at 47°- When allowed to stand in a desiccator, it loses water, becomes
liquid, and in the air reverts to the crystalline hydrate. When heated it poly-
merizes to Triphenyl-isomelamine. It forms phenyl-thiurea with HjS.

Carbodiphenylimide, C'^ j^'p^rr', is produced by the action of mercuric ox-
ide upon diphenyl-thiurea in benzene solution, when HjS is directly withdrawn
(p. 616) ; or by the distillation of a-triphenyl-guanidine, when aniline separates.
It is a thick liquid, boiling at 330°. It polymerizes upon standing, yielding a porce-
lanous mass, melting at 170°. When it absorbs water (boiUug with alcohol), it
yields diphenyl urea. It combines with HjS to diphenyl thiurea, and with aniline
to (i-triphenyl-guanidine. It forms very stable bases with orthophenylenediamine,
C6H^(NHj)2 {BerUhte, 22, 3186). .

Cyanuramide or Melamine Derivatives (p. 290).

Normal Triphenylmelamine, C3N3(NH.CgH5)3, is produced in the action of
cyauuric chloride on aniline, or by heating ethyl trithiocyanuric ester with aniline
(p. 290) to 250-300° (Berichte, 18, 3218): —

C3N3(S.CH3)3 -f 3NH,.C3H, = C3N3{NH.C,H5)3 + 3CH3.SH.

It consists of colorless needles, melting at 228°. Heated with hydrochloric acid
to 1 50°, it breaks up into aniline and cyanuric acid.

Hexaphenylmelamine, C3N3[N(CgH5)2j3, melts at 300° and sphts up into
aniline and diphenylamine when heated to 200° with hydrochloric acid. It is
formed by letting cyanuric chloride act upon diphenylamine.

Triphenylisomelamine, C3N3(CgH5)3(NH)3. On long standing, phenyl-
cyanamide polymerizes to this compound. Heating will effect the same. Or, it is
produced when cyanogen bromide acts on aniline. It crystallizes in thick needles
and melts at 185°. It dissolves in hydrochloric acid and forms double salts with
AuClj and PtCIj. On warming with hydrochloric acid, it successively loses its
NH-groups, oxygen entering, and the sole product is the triphenyl ester of iso-
cyanuric acid (p. 613) {Berichte, 18, 3225). In addition to the normal triphenyl-
melamine and triphenylisomelamine, asymmetrical triphenylamines are known
(Berichte, 18, 3226 ; 23, 1678).

Amidine derivatives (p. 293 and Benzenyl amidines).

In addition to the methods mentioned (p. 293), we can also produce the phe-
nylated amidines by permitting PCI3 or HCl to act upon a mixture of aniline
with acid anilides : —

CeH5.NH.CHO -f CeHj.NH, = CeHjiN^/^H + ^2°'
Formanilide. Diphenyl-methenyl-amidine.

PHOSPHORUS COMPOUNDS. 62 1

C,H,.NH:.C0.CH3 + C.H^.NH, = c'^l'^^C-CB, + H,0,

Acetanilide. Diphenyl-lthenyl-amidine.

or by conducting HCl into anilides, or by heating the same with HCl-salts of the
anilines l^Berichte, 15, 208 and 2449). They are feeble bases, and yield salts with i
equivalent of hydrochloric acid. When boiled with aniline they are separated into
aniline and acid anilides.

Diphenyl-methenyl-amidine (Methenyldiphenyl-diamine) results upon heat-
ing aniline with chloroform or formic acid to 180°, and by boiling phenyl-isocy-
anide, CgHg.NC, with aniline. It crystallizes from alcoBol in long needles,
mells at 135° and distils at 250°, with partial decomposition into CgHj.NC and
aniline.

Diphenyl-ethenyl-amidine melts at 131°.

Phenyl-ethenyl-amidine, CgH5N:C(NH2).CH3, from acetonitrile and HCl-
aniline (p. 293), is a liquid.

We can also include here the so-called anhydro- and aldehydine bases (p. 628),
which are obtained from the phenylenediamines of the ortho- series (see also
Benzenyl-amidine) .

PHOSPHORUS COMPOUNDS.

There is a series of phosphorus compounds corresponding to the benzene
amido-derivatives.

Phenylphosphine, CgHj.PHj, phosphaniline, is obtained by the action of
hydriodic acid upon phosphenyl-chloride, CgHj.PCl^. It is a liquid, boiling at
160° in a current of hydrogen, and possessing an extremely disagreeable odor.
It sinks in water and is insoluble in acids. When exposed to the air it oxidizes
to phosphenyl oxide, CgHj.PHjO, — a crystalline mass easily soluble in water.
Phenylphosphine combines with HI to the iodide, CgHs-PHjI, out of which
water again separates phenylphosphine.

Phosphenyl Chloride, CgHj-PClj, is formed by conducting a mixture of
benzene and PCI3 vapors through tubes heated to redness, by heating mercury
diphenyl with PCI3, and by the action of AICI3 upon benzene and PCI3. It is a
strongly refracting liquid, which fumes in the air, boils at 222°, and has a specific
gravity 1.319 at 20°. It forms the tetrachloride, C5H5.PCI4, with chlorine; this
melts at 73°. With oxygen it yields the o^j^/i/cWflS?, CjHg.PCljO, boiling at
260°. When the dichloride is heated with water we obtain phenyl-hypo-phos-
phorous acid, C5Hg.PHO.OH (melting at 70°), while the tetrachloride forms
phenylphosphinic acid, CeH5.PO.(OH)2, which melts at 158° (p. 155).

Phosphenyl chloride converts phenylphosphine into Phospho-benzene, C^
Hg.PiP.CsHj, corresponding to azobenzene, CgHg.NiN.CgHg.

Diphenylphosphine, (C5H5)2PH, is obtained from diphenylphosphor-
chloride. It is an oil, boiling at 280° (Berichte, 21, 1507). Diphenylphosphor-
chloride, (CgH5)2PCl, from mercury diphenyl, and phosphenyl-chloride, boils at
320° {Berichte, 18, 2108). .

Triphenylphosphine, (C5H5)3P, is produced from CgHg.FCl^, and brom-
benzene, or from PCI 3 and brombenzene by the action of sodium {Berichte, 18,
Ref 562) ; it cry.stallizes in large plates, melts at 75° and boils at 360°.

Triphenylphosphine readily enters into compounds of pentavalent phosphorus
(p. 169). It forms, with bromine, the dibromide, (CgHgjjPBrj, which is con-
verted by water or alkalies into the dihydroxide, (CgH5)3P(OH)2. At 100° this
passes into the oxide, (CsH5)3PO. The latter melts at 153° and boils above 360°.

622 ORGANIC CHEMISTRY.

Triphenylphosphine and sulphur unite to the sulphide, (CgH5)3PS, and with the
alkyl iodides to phosphonium iodides, like (CjH5)3P.CH3l (Berichte, i8, 562).

Phenoxyldiphenylphosphine, {C.^^^.O.C^'&^, is isomeric with triphenyl
phosphine oxide. It is produced by the action of phenol upon diphenyl phosphor-

V III

chloride (see above): (Q,^Vi.^)^YO, isomeric with (C.^\i^)^V.O.Q,^'&.^. This
isomerism proves ihe penlavalence of phosphorus in the compounds PXj (Berichte,
18, 21 18).

Toluene, xylene, and naphthalene form similar phosphorus derivatives. Analo-
gous arsenic compounds exist. Furthermore, analogous arsenic [Berichte, ig,
1031) and antimony compounds, e.g., Triphenylstibine, are known [Berichte, 18,
Ref. 444).

Phenyl-silico-chloride, C^Hj.SiClj, is prepared by heating mercury di-
phenyl and SiCl^ to 300°. It is a liquid which fumes in the air and boils at
197°. Water decomposes it into the compound, CgH5.SiO.OH, which maybe
considered as benzoic acid in which the I carbon is replaced by silicon, hence it
is called silico-benzoic acid. Alcohol forms the triethyl ether, CgHj.SifO.Cj
H5)3, boiling at 237°. Zinc-ethyl converts the chloride into triethyl-pJienyl-
silicide, C5H5.Si.(C2H5)3, boiling at 230°.

Tetraphenyl Silicon, Si(CgH5)4, is produced by the action of sodium upon a
mixture of SiCl4, chlorbenzene and ether [Berichte 18, 1540; ig, 1012). It is a
white powder, which separates in a crystalline form from benzene. It melts at
228° and distils beyond 300°.

The arsenic and silicon compounds constitute the transition to the metallo-
organic derivatives (p. 177); those containing tin, bismuth, mercury and lead are
known in the benzene series.

Mercury-Phenyl (C^Hjl^Hg, is formed by treating brombenzene in benzene
solution, for some time, with liquid sodium amalgam; the addition of some acetic
ether facilitates the reaction (p. 181). It crystallizes in colorless rhombic prisms,
melts at 120°, and can be sublimed. It assumes a yellow color in sunlight. It
dissolves readily in benzene and carbon disulphide, but with more difficulty in
ether and alcohol; in water it is insoluble. When distilled ^it decomposes for the
most part into diphenyl, benzene and mercury. Acids decompose it with forma-
tion of benzene and mercury salts. Haloid compounds, t. g., CjH^.Hgl, are
produced by the action of the halogens. Moist silver oxide converts them into
hydroxyl derivatives, e.g., CgH5.Hg.OH — a crystalline, very alkaline body, which
separates ammonia from ammonium salts.

Bismuth-Triphenyl, (CgH5)3Bi, is prepared by heating brombenzene and bis-
muth-sodium. It crystallizes, from hot alcohol, in needles or leaflets and melts at
82° [Berichte, 20, 54). When digested with concentrated hydrochloric acid it
breaks up into bismuth-trichloride and benzene.

Tin -Tetraphenyl, Sn(C8H5)4, may be produced by the action of tin-sodium
(25 <fo Na) upon brombenzene. It crystallizes in colorless prisms, melting at 226°.
It sublimes and boils above 420° [Berichte, 22, 2917).

Lead-Tetraphenyl, (C3H5)4^Pb, is formed by heating brombenzene with lead-
sodium and acetic ether. It is very much like the mercury-phenyl. It crystallizes
in minute needles, melting at 225°, and decomposes above 270° [Berichte, 20,
717).

ANILINE HOMOLOGUES. 623

ANILINE HOMOLOGUES.

The aniline homologues, like aniline, are obtained by the reduc-
tion of the nitro-derivatives of the homologous benzenes. Techni-
cally, the methylated homologues (toluidine, xylidene, cumidine)
are prepared by heating dimethylaniline or methyltoluidine hydro-
chlorides to 300° (p. 594).

Toluidines, CjH^^' ivrpr'- The three isomerides are formed by

the reduction of the three corresponding nitrotoluenes. Crude,
commercial toluidine (p. 590), obtained by reducing common nitro-
toluene, consists of solid para- and liquid ortho-toluidine ; the
former crystallizes out from the mixture.

To separate orthotoluidine from any para that continues in solution, the two are
converted into acetyl compounds by digesting them with glacial acetic acid ; in
this new form they are dissolved in 4 parts concentrated acetic acid, and 80 parts
of water are then added. The acetparatoluidine is precipitated, while the ortho-
body continues in solution. Technically, they are separated from each other (and
from aniline) by the different behavior of their HCl-salts toward sodium phosphate
{Berichte, 19, 1718, 2728).

The following mixtures are handled in commerce : Aniline oil for blue, consist-
ing of pure aniline; aniline oil for red, consisting of aniline, o-toluidine and
/-toluidine in almost molecular quantities, and aniline oil for saffron, obtained from
the distillate of the fuchsine fusion (fichappfis), is a mixture of aniline and o-tolu-
idine.

When the toluidines are directly oxidized they behave like the
anilines and usually change to azo-compounds ; should the aniido-
group, however, contain acid radicals, these acid toluides can be
oxidized by potassium permanganate, and by saponification yield
amido-benzoic acids. Furthermore, the acid-toluides can be chlori-
nated, brominated, and nitrated the same as the anilides. The
substituting negative group always arranges itself near the amido-
group (in the ortho- position). Substituted toluidines are obtained
by the saponification of these toluides.

Paratoluidiru (i, 4), from solid paranitrotoluene, crystallizes in large plates,
melts at 45°, and boils at 198°. It separates from boiling water, on cooling, in
hydrous crystals, that sublime on exposure to the air. Bleaching lime does not
color it. The acetyl compound, C^H^.NH.CjHgO, melts at 147°, and boils near
306°. Formyl toluide, C^H^.NH.CHO, is produced by distilling toluidine with
oxalic acid (p. 606) ; when distilled with concentrated hydrochloric acid it yields
(i, 4)-tolunitrile, which passes into terephthalic acid.

Methyl- and di-methyl-paratoluidine boil at 208°.

Upon heating /-toluidine with sulphur we obtain both thiotoluidine and dehy-
drothiotoluidine, Ci^HijNjS — the parent substance of 'Cos. primulines {see thio-
toluidine and Berichte, 22, 581, 969).

Nitrosotoluidines, C,Hg(N0).NH2, may be prepared from the nitrosocresols

624 ORGANIC CHEMISTRY.

by heating them with ammonium chloride and ammonium acetate (p. 599) f^Be-
richte, 21, 729)-

Orthotoluidine (l, 2) (Pseudotoluidine) does not solidify at — 20°, and boils at
199°; its specific gravity at 16° is i.oo. Bleaching lime and hydrochloric acid
color it violet, while a mixture of sulphuric and nitric acids gives it a blue color.
Ferric chloride precipitates a blue compound (toluidine blue) from its hydro-
chloric acid solution. Its acet-compound melts at 107° and when oxidized with
potassium permanganate and saponified yields ortho-amido benzoic acid [Berichte,
14, 263). It forms four isomeric nitro-orthotoluidines (Annalen, 228, 240) by the
entrance of NOj.

Metatoluidine (l, 3), from metanitrotoluene {Berichte, 22, 840) and metanitro-
benzaldehyde (Berichte, 15, 2009), does not solidify at — 13°, has a specific gravity
of 0.998 at 25°, and boils at 202°. Its acetyl compound melts at 65°.

Ditolylamine, (C8H4.CH,)jNH, is produced like diphenylamine (p. 603) by
heating HCl-toluidine with toluidine. It is a crystalline compound, boiling near
360°.

Xylidines, C5H3(CH3),.NHj.

The six possible isomerides are known. Three are derived from metaxylene,
two from orthoxylene, and one from paraxylene (Berichte, 18, 2669). The com-
mercial xylidine, obtained from dimethylaniline, serves for the preparation of red
azo-dyestuffs, and consists chiefly of amido-paraxylene (Berichte, 18, 2664) and
amido-metaxylene (Berichte, 18, 2919).

Amidotrimethyl-benzenes, CgH2(CH3)3.NH2. The commercial product
is made by heating xylidine hydrochloride with methyl alcohol to 256° under
pressure; it serves for the preparation of red azo-dyestuffs and contains cumidine
and mesidine (Berichte, 15, 1011,2895). Cumidine \i Pseudocumidine of the
structure (l, 2, 4, 5 — NHj in 1) {Berichte, 18, 92 and 1 146); it consists mainly
of nitropseudocumene ; it melts at 63°, boils at 235°, and forms a nitrate that
dissolves with difficulty. Pseudocumene, €5113(0113)3 (i, 3, 4), is produced by
boiling its hydrazine compound, C5H2(CH3)3.NH.NH2, with copper sulphate
(see p. 633). Durylic acid is obtained by replacing the amido-group by bromine,
and this by CO2H. Mesidine, amido-mesitylene, is obtained from nitro-mesity-
lene, and boils at 227° (Berichte, 18, 2229).

Amido-Isodurene, CgH(CH3)j.NH2, is produced by heating pseudocumidine
hydrochloride or mesidine hydrochloride with methyl alcohol. It boils at 250°.
The replacement of its amido group by hydroxyl yields a tetramethylphenol,
melting at 8l° (Berichte, 18, 1 149).

Amido-pentamethyl Benzene, Cg(CH3)5.NH2, is very readily made by heating
pseudocumidine and methyl iodide to 250° (Berichte, 18, 1821). It melts at
152° and boils at 277°. The replacement of its amido group gives rise to penta-
methylphenol, C3(CH3)5.0H. '

Homologues of aniline with higher alkyls are easily obtained on heating ani-
line with fatty alcohols and ZnClj to 270-280° (p. 599) ; the alkyl assumes the
para-position with reference to the amido group. /-Amidoethylbenzene,
C8H^(C2H5).NH2, also obtained from nitroethyl benzene {Berichte, 17, 767,
2800), boils at 214°. Amidopropylbenzene, C3H^(C3Hj).NH2, boils at 225°,
the isopropyl compound at 217° {Berichte, 17, 1231) (see Berichte, 21, 1157).
Amidoisobutylbenzene, C3H4(C4Hg).NH2, is easily obtained by heating ani-
line hydrochloride to 230° with isobutyl alcohol (Berichte, i8, 1009), and boils at
231°. Amido-octyl Benzene, C5H4(CgHi,)NHj, from normal octyl alcohol,
melts at 19°, and boils at 310° [Berichte, 18, 133).

DIAMIDO COMPOUNDS. 625

DIAMIDO COMPOUNDS.

The diamidobenzenes or phenylene-diamines,C6H4(NH2)2,
are formed by the reduction of the three dinitrobenzenes or nitro-
anilines (p. 598) with tin and hydrochloric acid; they can be
obtained, also, from the six diamidobenzoic acids, C6H3(NH2)2.
CO2H, by the loss of carbon dioxide. They are also produced by
the reduction of the nitroso compounds of the tertiary anilines, e. g.,
NO.CeH4.N(CH3)2 (p. 598). The monamines can be converted
into the diamines by first changing them to amido-azo-compounds,
and then decomposing the latter by reduction (p. 645).

The diamines are colorless solids, but on exposure to the air
they become colored. They are di-acid bases, forming well-defined
salts. Ferric chloride imparts an intense red color to their solution.

Diamidobenzenes or Phenylenediamines, CjH^(NH2)2.

o-Diamidobenzene (i, 2), four-sided plates, melts at 102° and boils at 252°.
Ferric chloride imparts a dark red color to its HCl-solution. When o-diamido-
benzene (o-phenylene diamine) is shaken with benzoyl chloride and caustic soda
the afj^^M^oj// derivative is formed — CgH^.(NH.CO.CgH5)2 (p. 312 and Berichte,
21, 2744). Diacyl derivatives of the «- diamines are easily formed by heating with
acid anhydrides [Berichle, 23, 1876), whereas if the free acids are employed
ethenyl amidines are produced (p. 628). m-Phenylenediamine (i, 3), readily
obtained from common dinitrobenzene, melts at 63° and boils at 287°. Very
dilute nitrous acid solutions are colored intensely yellow by it ; it can therefore
be employed for the quantitative estimation of the former in aqueous solution
(BericAte, 14, 1015). It combines with carbon disulphide to produce a peculiar
compound, C5H4(NH)2CS (Berichte, 21, Ref. 521). p- Phenylenediamine (l, 4)
melts at 147° and boils at 267°. Manganese peroxide and sulphuric acid
convert it into quinone on boiling. If allowed to stand exposed to the air it
oxidizes to green-red crystals, CgHgNj (Berichte, 22, Ref. 404). Its dimethyl

compound, CgH^^-vrVr ^'^, has already been described as /-amido-dimethyl-

aniline (p. 601.) The tetramethyl derivative serves as a reagent for ozone
{Berichte, ig, 3196).

Diphenylated diamidobenzenes, C5H4(NH.CgH5)3, are produced by heating
resorcinol and hydroquinone, C^^IX)^, with aniline and CaClj or ZnCl2 (see
dioxydiphenylamine, p. 604).

Triamidobenzenes, 'CgH3(NH2)3. The adjacent (1, 2,3) is obtained from
triamidobenzoic acid (from chrysanisic acid). When pure it is colorless, melts at
103° and boils at 330° It even reduces silver solutions in the cold, is colored
violet then brown by ferric chloride, and dissolves in sulphuric acid, containing a
little nitric acid, with a deep blue color. The unsymmetrical (1,2,4) is obtained
by the reduction of a-dinitroaniline (p. 598), and by the decomposition of
chrysoidine {Berichte, 15, 2197) ; it forms a crystalline mass and is colored a
wine red by ferric chloride {Berichte, 17, Ref. 285). When oxidized by air, it
changes to a eurhodine dyestufF {Berichte, 22, 856).

Tetra-amido benzenes, C5H2(NH2)4. The symmetrical (l, 2, 4, 5) variety
is formed by the reduction of dinitro-W2-phenylenediamine. It oxidizes very rap-
idly when liberated from its salts. It contains two amido-groups in the ortho- and
para-positions, hence it exhibits all the reactions of the ortho- and para-diamines

626 ORGANIC CHEMISTRY.

(see below) [BerichU, 22, 440). The adjacent (i, 2, 3, 4) variety, produced by
the reduction of diquinoyl-tetroxime, C5Hj(N.0H)j, is also quite easily oxidized,
and reacts like an orthodiamine [Berichte, 22, 1649).

Penta-amido benzene, CgH(NH2)5, from trinitro-diamine, is very unstable
on exposure to the air {^Berichte, 21, IS47)-

Diamidotoluenes, Toluylene-diamines, CsH3(CH3)(NHj)j. o-p-Diamido-
toluene (i, 2, 4 — CHj in i), obtained by the reduction of dinitrotoluene, consists of
long needles, sparingly soluble in cold water, fusing at 99° and boiling at 280°. It
is used in the preparation of toluylene red,

m-p-Diamidotoluene (i, 3, 4 — CH3 in l), with the aNH^-groups in the ortho-
position, is obtained from nitroparatoluidine, forms scales that dissolve easily in
cold water, melt at 89° and boil at 265°. Of the ortho-diamines, this one is
most readily prepared. o-m-Diamido-toluene (l, 2, 3) (the two amido-groups are
in the ortho-positions) is obtained from the corresponding nitroorthotoluidine. It
melts at 62° and distils at 255° {^Annalen, 228, 343). 0-0-Diamidotoluene (l, 2,
6), from o-nitroorthotoluidine, melts at 103°-

Differences between the ortho-, meta- and para-diamines. — The
three isomeric diamines differ markedly in numerous reactions, and
the ortho-derivatives especially are characterized by their capability
of forming various condensation products.

(1) The paradiamines, when digested in the warm with ferric chloride, are oxi-
dized to quinones, e.g., CjH^Oj, readily recognized by their odor. The same re-
agent precipitates from the orthodiamines (their salts) intensely colored compounds
of complex constitution. Thus, orthophenylenediamine yields the ruby red com-
pound, C24H18N5O.2HCI {Berichte, 17, Ref. 431).

(2) Nitrous acid (or NaNO^) converts the/3?-a-diamines (their salts) into diazo-

compounds, e.g., CgH^cf ^'y! the ^^^te-diamines, on the contrary (as one NHj

group is diazotized and two molecules unite), yield yellow brown azo-dyes, of the
type of phenylene brown. The same products result from the action of the diazo-
chlorides (see chrysoidine) upon the meta-diamines. In very acid solution, and
when there is a constant excess of acid (nitrous) the meta-diamines are also capable
of forming diazo derivatives [Berichte, 19, 317). The ortho-ASxmvae^, when acted
upon by the nitrous acid, yield azj/«/i/o-compounds, e.g., Azimidobenzene.

(3) When the hydrochlorides of the three isomerides are digested with ammo-
nium sulphocyanide, disulphocyanides, like CgH^^^^^- ^ arg produced.
On heating these to 120°, we discover that the orthodiamines are changed \.q phe-
nylene sulphureas, C5H^(^^„>CS. These are not altered by digestion with an

alkaline lead-solution (not desulphurized) ; while the derivatives, obtained from the
meta- and /a^-s-diamines are immediately blackened by the alkaline lead solution
(Reaction of Lellmann, Berichte, 18, Ref. 326). All diamines unite in a simi-
lar manner with the mustard oils, to form phenylene disulphalkylureas (see p.
389) ■■—

C H CNH ■( -4- aCS-N C H — C H /NH.CS.NH.C3H5.
i^-en^^i^n^^j -f- 2.K,x^.is.^^a.^ — '-6"4\nh.CS.NH.C3H5.

ANHYDRO-BASES. 627

If these products be fused, those from the ortho-diamines decompose into o-pheny-
lenesulphurea and dialkylsulphureas : —

P „ /NH.CS.NH.C3H, _ p „ /NH. p<j , P0/NH.C3H5.

the fused mass instantly becomes crystalline, and the resulting phenylenesulphurea
is not turned black by alkaline lead solutions. The zB^/a-diamine derivatives melt
with decomposition, while those of the para-, after fusion, are completely broken
up (Berichte, 18, Ref. 327, and 19, 808).

The ortho-phenylene diamines yield peculiar bases by their union with carbo-
diphenylimide (p. 620). With phosgene they form phenylene ureas, e.g.,

^6^*\NH>^° (-S^nVte, 23, 1097).

The para-diamines are also capable of yielding various dyestuffs. Mixed with
primary amines (or phenols) and oxidized at the ordinary temperature, they are
converted into indoamine a.nA indophenol dyestuffs; at higher temperatures, the
so-called safranines are produced. When oxidized with ferric chloride in the
presence of HjS, all the para-diamines, containing a free NHj-group yield sul-
phurized dyes of thio-diphenylamine (Lauth's Dyestuffs, p. 605).

With the diazo-compounds, the meta-diamines form azo-colors (see above) while
quinoxaliue and phenazine colors are obtained from the ortho diamines by the
action of ortho-diketones, etc.

Condensation Products oftheOrthodiamines. — The ortho-diamines,
in which the 2NH2-groups occupy the ortho-position, are capable of
forming peculiar compounds, in which the two nitrogen atoms of
the amido-groups are joined by one or two carbon atoms. They
belong partly to the quinoxalines and partly to the phenazines.
Analogous amidines are obtained from the amidophenols and amido-
thiophenols (see those of the ortho-series).

Amidine derivatives, or ankydrohases of the ortho-diamines are obtained: —

( 1 ) By reducing the ortho- nitro acid anilides with tin and hydrochloric or acetic
acid, the NO^-groups being converted into NHj and water eliminated at the same
time — Anhydrobases, of Hobrecker and Hiibner (Annalen, 209, 339) : —

CaH.<^0,^°-^"^ + 3H, = C,H,/^H\c (,jj^ ^ ^jj^Q^

Ortho-nitro-acetanilide. Ethenyl-phenylene-amidine.

C.H<^5^°-^^^= + 3H, = C,H,/NH\c.c,H,.-^ 3H,0.

tj-Nitro-benzanilide. Benzenyl-phenylene-amidine.

(2) The same anhydrobases, or amidines, are directly produced from the ortho-
diamines on heating them with acids (e.g., formic acid, acetic acid, benzoic acid,
phthalic acid) ; the acid anilides formed at first (Berichte, ig, 1757), lose water
{Berichte, 8, 677 ; 10, 1 123) : —

C,H3(CH3)/JJg^ + CH3.CO.OH = C,H3(CH)3/^H\c.cH3 + 2H,0.

o-Toluylene Diamine. Toluylene-Etlienyl Amidine.

The same products result on heating the ortho-diamines with acetoacetic ester
(Berichte, 19, 2977 ; 12, 953) ; paraphenylene diamine, on the other hand, forms
an anilide of aceto acetic acid (Berichte, 19, 3303).

628 ORGANIC CHEMISTRY.

(3) The ortho-diamines yield similar derivatives with the aldehydes (benzalde-
hyde, furfurol, salicylic aldehyde) — Aldehydine bases of Ladenburg (Berichte,
II, 590):—

CHj.CgHj

<^6"*\NH^ + 2C0H.CeH, = C^H^ Cecils + 2H,0.

Ecnzaldehyde. ^ -^

If the hydrochloric acid salts of the diamines (with 2HCI) be employed in this
reaction, one molecule of hydrochloric acid is set free, and the ortho-diamines can
thereby be readily distinguished from the meta- and para-diamines (^Berichte, 11,
1650).

The latest investigations prove the aldehydine bases to be real amidines, inas-
much as benzaldehydine can also be prepared from benzenyl-phenylene amidine
(see above) by heating with benzyl chloride, CgHj.CHjCl {Berickte, 19, 2025).
The fatty aldehydes are also capable of yielding analogous aldehydine bases {£e-
richte, 20, 1585).

Condensation products are obtained when ihifree diamines act upon aldehydes
{Berichte, 22, 2724).

The phenylene amidines (anhydrobases and aldehydines) are perfectly analogous
to the diphenylene amidines (p. 620). These are crystalline and very stable com-
pounds. Being monacid bases, they generally form well crystallized salts. They
do not unite with acid chlorides or anhydrides. They combine with the alkyl-
iodides (l and 2 molecules) to ammonium iodides, yielding corresponding hydrox-
ides with caustic potash. /■NTTTv

Phenylene-methenyl Amidine, CgH^:^ „^CH, phenylene-formamidine,

(p. 293), from o-phenylene diamine and formic acid, melts at 167°. Phenylene-
ethenyl Amidine, CgH^C^^^^^^C.CHj, phenylene-acetamidine, melts at 176°.

Phenylene benzamidine, C^H^i^j-^ C.CjH^, melts at 280°. Benzalde-
hydine results upon heating it with benzyl chloride (see above). An oxy-deriva-
tive of methenyl amidine is produced on heating o-toluylene diamine with imido-
, carbonic ester (p. 384) : —

^'^Knh' + HN:C.g;^g = C,H,/^g\c.O.C,H, -f NH3 + qH^.OH.

On heating the ethenyl-compound with hydrochloric acid, we get
Toluylene-oxy-methenyl amidine, or Toluylene Urea, C,Hj:C^at^C.

OH, or C,Hg('^j,TT>CO (tautomeric forms), which can also be formed by heat-
ing (p-toluylene-diamine with urea {Berichte, 19, 2652). o-Phenylene-sulphurea,
CgH^cf j^jT>CS (p. 627), is analogous to o-toluylene-urea.

A very interesting condensation of the ortho-diamines is that with
glyoxal, CHO.CHO and other dicarbonyl derivatives, — .CO.
CO. — , when they form basic compounds of the quinoxaline type :

DIAZO-COMPOUNDS. 629

-NHj CHO ,N:CH

CsHy +1 =C,h/ I +2H,0,

^NH^ CHO ^N:CH

and also of that of phenazine, ^^/S\Q,^i. (see these).

Upon this behavior Hinsberg and Korner have based the reaction
for the detection of the ortho-diamines by means of phenanthra-
quinone. A more delicate test is obtained by using croconic acid
{Berichte, 19, 2727).

The ortho-diamines unite with grape-sugar {Berichte, 20, 281 an^
495)-

DIAZO-COMPOUNDS.

The amido-group is directly replaced by hydroxyl, when nitrous
acid acts upon the primary amido-derivatives of the marsh-gas
series (p. 161) : —

R.NHj + NOjH = R.OH + Nj + H^O.

The benzene amido products, on the other hand, first yield inter-
mediate compounds — the so-called diazo-compounds — which can
be further transformed into hydroxyl derivatives : —

C,H,.NH,. CeH5.N,.N03. C.H^.OH.

Amido-benzene. Diazo-benzene Nitrate. Phenol.

We obtain either diazo- or diazo-amido compounds, according to
the conditions of the reaction. If nitrous acid (or its vapors) be
permitted to act on the salts of amido-derivatives in aqueous solu-
tion, salts of the diazo-compounds are formed : —

CeHj.NHjNOaH + NO^H = CeH5.Nj.NO3 + 2H,0.
Aniline Nitrate. Diazo-benzene Nitrate.

If, however, we act on the free amido-derivatives, in alcoholic or
ethereal solution, diazo-amido-compounds result : —

2CeH5.NH2 + NO,H = C5,H5.N,.NH.C5H5 + 2H,0.

Diazo-amido-benzene,

The diazo compounds are produced at first, but they then com-
bine with a second molecule of the free base and form diazo-amido-
derivatives (p. 631): —

CeH5.N,.N03 + CeH^.NH, = CeH^.N^.NH.C.H^ + NO3H.

Instead of using free nitrous acid (its vapors) with amido-salts, we can obtain
the diazo-derivatives more easily and in purer form, by dissolving the amido-com-
pounds in two equivalents of dilute nitric or sulphuric acid, and then adding an
equivalent amount of potassium or sodium nitrite to the solution {^Berichte, 8,
1073) :—
esH5.NH2.NO3H + NO3H -f NOjK = CeH5.N2.NO3 + 2H2O + NO3K.

630 ORGANIC CHEMISTRY.

To obtain the diazoamido-compounds add amyl nitrite or ethyl nitrite (I mole-
cule) to the ethereal solution of the amido-derivative (2 molecules) and allow the
latter to evaporate over sulphuric acid {ibid) : —

aCeHj.NH,. + C.Hj.O.NO = C,li^.T>i^.^n.C,li, + H,0 + C^H^.OH.

They are more easily prepared by adding the aqueous solution of NOjK and
KOH (i molecule each) to the aqueous solution of the HCl-anilines (2 mole-
cules) : —

2C5H5.NH2.HCI 4- NO2K -f KOH = CsH5.Nj.NH.C5H5 -f 2KCI + 3H2O.

'It is frequently recommended to substitute sodium acetate for alkalies (Berichie,
'^, 641). In this case the reaction proceeds so that the diazo-compound is formed
by NOjK and I molecule of CgHs.NH^.HCl, and this immediately combines
with the aniline liberated by the KOH and forms the diazo-amido-product (see
amido-azo-benzene). All the above reactions must be executed in the cold.

Nitrous acid converts the secondary aniline bases into the same diazo-com-
pounds, the alkyl group disappearing as alcohol : —

C,H5.NH(C,H,).N03H + NO,H = C,n,.N,.1^0, + H,0 + C.H^.OH;

whereas nitroso-compounds result if potassium nitrite be employed (p. 600).

Further action of nitrous acid on the dissolved diazoamido-derivatives trans-
forms them into diazo-compounds, and the latter, finally, by action of water, into
phenols.

Another procedure, occasionally applicable in diazotizing, consists in letting
zinc dust and hydrochloric acid act upon the nitrate of the diazo-derivative
(Mohlau) : —

C6H5.NH2.NO3H -f Zn -f 3HCI = CgHs.NjCl + ZnClj + 3B.fi.

P. Griess first discovered the diazo-compounds early in the '6o's;
their constitution was explained by Kekule. They all contain the
diazo-group of two nitrogen atoms, which on the one side replaces
an atom of hydrogen in benzene, and on the other is attached to a
monovalent group, as seen in the following formulas : —

Diazobenzene nitrate, CjHg.N^N.O.NOj

sulphate, CsH5.N=N.O.S03H

chloride, C5H5.N=NC1

Potassium diazobenzene, C5H5.N:=N.OK

Silver « C5H5.N=N.OAg

Diazo-amidobenzene, CjH5.N=N.NH.C5H5

Diazobenzene sulphonate, C5H5.NiiN.SO3H.

The structure of the diazo-compounds is now fully proved by the existence of
the so-called tetrabrombenzene-diazosulphonic acid, CgBr^^ cA / I^Berichte, 9,
1537), and also by their relations to the hydrazines (Annalen, igo, 100).

Free diazo-benzene has not been as yet prepared pure, nor ana-
lyzed; it, however, corresponds to the formula, CsHs.N^iN.OH.

The diazo-chlorides form double salts with auric and platinic
chlorides, e. g. : —

C5H5.N,Cl.AuCl3 (C3H5.N,Cl),.PtCl,.

DIAZOAMIDO-COMPOUNDS. 63 1

The diazobromides also combine with two additional atoms of
bromine, yielding J>erl>romides : —

CgHg.NjBr.Brj, Diazobenzene Perbromide.

Potassium sulphite converts the sulphates into diazosulphonic
acids : —

CsHj.NvSOiH H- SOjKj = CeH5.N2.SO3K + SO^KH.

These pass into hydrazines when reduced.

The Diazoamido-compounds are also produced by the direct
action of salts of the diazo-derivatives upon primary and secondary
anilines {Berichte, 14, 2448) : —

C5H5.Nj.NO3 + 2C6H5.NH, = CeH^.N^.NH.CeHj + C,H,.NH,.HN03,
C,H5.N,.N0, +2^|j^5\nh = CeH5.N,N/^|Ha+ ^|j^5\nH.N03H;

also : —
CjH5.Nj.OK + C5H5.NH2.HCI = CeH5.N2.NH.C8H5 + KCl + HjO.

This explains their formation by the action of nitrous acid upon
the free amido-compounds (p. 630). See p. 638 for the constitu-
tion of the diazo-amido-compounds of substituted anilines.

They can also be obtained by the action of the nitroso-amines upon the primary
amido- bodies: —

(CeH5),N.N0 + NHj.CeHj = (CeH5)2.N.N:N.CsH5 + H^O.

It is not only with the primary and secondary anilines, but also with the primary
and secondary (not tertiary) amines of the fatty series, with which the diazo-com-
pounds are capable of combining, thus forming mixed diazoamido compounds,

CeH5.N2.NH.C2H5 and CeHj.Nj.NCCHj),.

When sodium alcoholate and alkyl iodides act upon the diazo-
amido derivatives the hydrogen of the NH -group is easily replaced
by the alkyls. An excess of cold hydrochloric acid will reduce
the resulting diazo-alkylamido- compounds into diazochlorides and
alkyl anilines :—

CeH5.N2.N(CH3).CeH5 -f HCl = CeH^.NjCl ^ NH/g^j|^.

This is a proof of the accepted constitution of the diazoamido
derivatives {Berichte, 19, 2034, 3239).

The salts of the diazo-compounds are mostly crystalline, color-
less bodies, which speedily brown on exposure to the air. They are
readily soluble in water, slightly in alcohol, and are precipitated

632 ORGANIC CHEMISTRY.

from the latter solution by ether. They are generally very un-
stable, and decompose with a violent explosion when they are
heated, or struck a blow.

The diazo-salts are first obtained in solution, from which it is rather trouble-
some to get them in a solid form (p. 636). They can be obtained as solids by
applying the aniline salts in alcoholic solution and acting upon the same with amyl
nitrite [Btrichie, 23, 2995).

The diazo-derivatives are very reactive,, and enter numerous,
i^adily occurring reactions, in which nitrogen is liberated, and the
diazo-group in the benzene nucleus directly replaced by halogens,
hydrogen, hydroxyl, and other groups.

(1) When the salts (sulphates are best) are boiled with water, the
diazo-group is replaced by hydroxyl and phenols are produced : —

CeHj.Nj.NOa + H,0 = C,H,.OH + N, + NO3H,
CeH^.Nj.Br + H,0 = C5H5.OH + N^ + HBr.

Mononitrophenols result upon digesting in the warm with i molecule of nitric
acid {JSerichte, 18, 1338). See Berichte, 20, 1 137, for abnormal transpositions.

The substitution of the diazo-group by the sulphydrate group (SH) occurs upon
digesting diazo-benzenesulphonic acid with alcoholic potassium sulphide {Berichte,
20, 350) :—

In the same manner, when mercaptan acts upon diazobenzenesulphonic acid,
a compound results, which, upon standing or warming, liberates Nj, and is trans-
posed into the ethyl sulphid-derivative [Berichte, 17, 2075) : —

(2) If alcohol be employed instead of water, then hydrogen will
enter for the diazo-group, and hydrocarbons result. The alcohol
is oxidized to aldehyde : —

CeH,.N,.HSO^ + C,H,0 = CeH^ + N, -f- SO^H^ -1- C.H^O.

Instead of first converting the amido- into the diazo- compounds, we can directly
substitute H for NHj, by adding their compounds to alcohol saturated with NjO,
(ethyl nitrite), and then applying heat. In this way diazo-derivatives appear at
first, but they are at once decomposed by the alcohol. Sometimes it is advisable to
dissolve the amido-derivatives in a little concentrated sulphuric acid, lead nitrous
acid into the solution, and then decompose with alcohol [Berichte, g, 899). It
has occurred upon boiling with alcohol that the diazo-group was not replaced by
hydrogen but by oxy-ethyl (O.CjHj); this was the casein slight degree with
aniline and toluidine [Berichte, 17, I917 ; 18, 65). If the dry diazo salt be de-
composed with alcohol, phenol ethers are the chief products [Berichte, 21, Ref.
96; 22, Ref. 657).

The replacement of the diazo-group by hydrogen is sometimes effected by its
conversion into the hydrazine derivative and then boiling this with copper sul-

DIAZO-COMPOUNDS. 633

phate or ferric chloride (see phenyl hydrazine). The reaction taking place on
boiling the diazo-chlorides with a stannous chloride solution, is, in all probability,
dependent upon the intermediate formation o{ hydiazines {Beric/iie, 17, Ref 741) :

CeH^(C4Hs,).N,Cl + SnC], + H,0 = CeH5(C4H3) + N^ + SnOCl^ + HCl.

An analogous proced,ure for the replacement of the diazo-group by hydrogen con-
sists in dissolving the dlazo-compound in caustic soda and adding a solution of
stannous oxide in sodium hydroxide {Berichte, 22, 587).

(3) Chlorbenzenes are formed, if the PtClj-double salts (p. 630)
are heated alone, or, what is better, with dry soda or salt : —

(CeH,.N,Cl)j.PtCU = 2C,H,C1 + N^ + 2CI, + Pt.

When the diazo-perbromides are subjected to dry distillation, or
boiled with alcohol (the latter is oxidized to aldehyde), bromben-
zenes are formed : —

C,H,.N,.Br3 = CeHjBr + N^ + Br^.

On digesting the diazo-salts with hydriodic acid, iodobenzenes
separate: —

CeH,.N,.SO,H + HI = CeHJ + N, + SO,H,.

HBr and HCl react similarly, providing the diazo-compounds contain additional
negative groups [Berichte, 8, 1428, and 13, 964).

The diazo-group in the three diazocinnamic acids can be replaced by chlorine
on boiling viiWi concentrated HCl-acid [Berichte, 16, 2036).

The dry sulphates of the diazo-benzoic acids deport themselves in a similar
manner vfhen heated with the concentrated haloid acids [Berichte, 18, 961).

In addition to phenols, large quantities of chlor- and brom-benzenes are pro-
duced on boiling the benzene diazochlorides with hydrochloric or hydrobromic
acid [Berichte, 18, 337, 1936).

(4) Remarkable transpositions of the diazo salts have been effected
through the agency of cuprous compounds (Reactions of Sandmeyer).

Chlorbenzenes result upon heating diazo-chlorides, in aqueous
solution, with a solution of cuprous chloride. At first compounds,
containing cuprous chloride, are produced {Berichte, ig, 810), but
these rapidly undergo further decomposition : —

CeH^.N^CLCu^Cla = C^H^Cl + N, -f Cu^Cl^.

The yield is greater, if the solution of the diazo-chloride be allowed to gradually
run into the boiling HCl-solution of cuprous c!a\on&t [Berichte, 17,1633; 23,
1880). Or cuprous chloride is added to the HCl-solution of the amide, the liquid
then healed to boiling, and sodium nitrite added [Berichte, 17, 2651). In this
way amidophenols yield chlorphenols, and phenylenediamines yield dichlorben-
zenes. By adding potassium bromide, the diazo-group is replaced by bromine and
bromphenols are formed. Sandmeyer's method is especially adapted for the for-
mation of chlorine and bromine derivatives. The fluorine and iodine derivatives
are better prepared from diazo-amido compounds [Berichte, 21, Ref. 97).

53

634 ORGANIC CHEMISTRY.

The diazo-group can be replaced by the nitro-group, forming
nitro-benzenes. This may be accomplished by adding the diazo-
benzene nitrite solution to freshly precipitated cuprous oxide [^Be-
richte, 20, 1495; 23, 1630):—

C6H,.N,.N0, = CeH^CNO,) + N,.

If copper sulphate be mixed with potassium cyanide, and the di-
azochloride solution added to it, the diazo-group will be displaced
by the cyanogen group and nitriles will result : —

CjHj.NaCl + CNK = CeH5.CN + N2 + KCl.
Thus the three isomeric nitroanilines, CgH^^^^Q '^, yield three nitrocyanides,

CgH^^™ , which can be further converted into the three nitrobenzoic acids,

^ /CO H

C|,H^(N02).C02H. Likewise, the three amido-benzoic acids, CjH^^^jpj^ >

can be transformed into the three phthalic acids, C^^iZO^Vj^ {Berichte, 18,
1492). Thus aniline yields nitrobenzene (^Berichte, 20, 1495).

Sulphocyanides {^Rhodanides) result when the diazo-salts are boiled with potas-
sium and cuprous sulphocyanides (Berichte, 23, 738, 770) : —

CsH^.N^Cl + CN.SK = CgH^.SCN + N^ -)- KCl.

A modification in Sandmeyer's method, which frequently is of
practical advantage, consists in using reduced copper, as a substitute
for cuprous chloride (Gattermann, Berichte, 23, 1219; compare
Berichte, 23, 1881). In this way it is also possible to introduce the
group N: CO thus iorming phenylisocyanates, if a potassium cyanate
solution and copper powder be added to the diazo-salt (Berichte,
23, 1223) :—

CgH^.N^Cl + CNOK = CsH5.N:CO + N2 + KCl.

If copper powder or zinc dust acts upon diazo-benzene sulphate diphenyl results
[Berichte, 23, 1227). Upon boiling diazo-benzene sulphonic acids with copper
powder and formic acid hydrogen replaces the diazo-group and benzene sulphonic
acids are formed [Berichte, 23, 1632).

The diazo-amido- compounds, e. g.,. CsHs.Nj.NH.CsHj, diazo-
amidobenzenes, are generally yellow-colored, neutral bodies which
do not combine with acids. They are insoluble in water, but dis-
solve in alcohol, ether and benzene. As a general thing they are
more stable than the diazo-compounds, and do not often change
color on exposure to air ; yet they undergo reactions analogous to
those of the diazo-derivatives. In so doing they are resolved into
their components : the amido-compound breaks off, while the
diazo-group sustains the corresponding transformation : —

CsH,.N,.NH.CeH5 -I- 2HBr = C^H^Br -|- N, -f CeH^.NH^HBr,
CeH5.N,.NH.C,H5 -j- H,0 = C^H^.OH + ^i+ CeHj.NH,.

DIAZO-COMPOUNDS. 635

Phenol and aniline are also produced by boiling witb concentrated hydrochloric
acid. By using cold, concentrated hydrochloric acid the immediate action is the
decomposition into diazo-chloride and aniline. The reaction is especially adapted
to the formation of fluorine derivatives (p. 583).

Nitrous acid converts the amido- into the diazo-group : —

CeH,.N,.NH.CeH5 + NO,H + 2NO3H = aC.HB.N^.NOj + 2H,0.

On boiling the alcoholic solution with sulphurous acid, the diazo-
group is replaced by the sulpho-group, with formation of benzene-
sulphonic acids {Berichte, 9, 1715) : —

C,H3.N,.NH.CeH5 + 2SO3H, = CeH,.SOsH + N, + NH^.C.H^.SOaH^.

The diazo-derivatives of the substituted amides react similarly.
Therefore the conversion through the diazo- or diazoamido-com-
pounds is an excellent means of transforming amido-derivatives
(and also nitro-) into the corresponding halogen- and oxy-com-
pounds. Thus, we successively obtain from the three isomeric
nitranilines the following derivatives belonging to the three
series : —

CeH,{NO, c,H,{NO^ C,H,{NO. „, C,H,{gg-and

lOH-

Conversion of Diazo- into Azo- Compounds. — Besides the changes
described the diazo-compounds exhibit other noteworthy reactions.
While they form diazo-amido-derivatives with primary and second-
ary anilines (p. 631), they yield amido-azo-derivatives with tertiary
anilines (p. 642), as the diazo-group encroaches upon a new ben-
zene nucleus : —

C.Hs.N^.NO, + C„H,.N(CH3), _ C,H,.N,.C„H,.N(CH3), + NO3H.

Dimethylamido-azobenzene.

They act in the same manner on the phenols, the phenolsulphonic
acids and phenylenediamines, C6H4(NH2)2, of the meta-series, pro-
ducing various classes of coloring substances (the chrysoidines and
tropseolines), which belong to the group of azo-compounds (p. 640).

In an analogous manner, the diazo-amido compounds are trans-
posed into azo-derivatives by simply standing, or through the action
of anilines (p. 642) : —

CsH5.N2.NH.CeH5 yields C6H5.Nj.CeH4.NHj.

Diazoamido-benzene. Ami^o-azo-benzene.

6;^6 ' ORGANIC CHEMISTRY.

For the relations of the diazo- to the hydrazine derivatives, see
latter.

Seaciions of the Diazo-Compounds. — All, even the diazo-amido-compounds,
give intense colorations (reaction of LiebermannJ, if added to a mixture of phenol
and concentrated sulphuric acid. The nitroso-compounds (and also the nitrites)
do the same. When an alcoholic solution of meta-diamido-benzene (or other
meta-diamido derivatives) is added to a similar solution of the diazo-derivatives,
red or brown colorations result ; the diazoamido-bodies react under these condi-
tions only after the addition of acetic acid {Berichte, g, 1309). The resulting
azo-derivatives belong to the chrysoidines (p. 643).

Diazobenzene Nitrate, CeHj.Nj.NOs, is formed by the action
of nitrous acid upon an aqueous or alcoholic solution of aniline
nitrate, or upon an ethereal solution of diazo-amidobenzene (in
presence of nitric acid).

Preparation. — Pour a little water over the aniline nitrate. Cool the flask with
ice from the outside and conduct in nitrous acid (from ASjOj and HNO3, specific
gravity 1. 35 (see Berichte, 18, Ref. n6) until all the substance has dissolved and
potassium hydroxide, added to a small portion of the mixture, does not separate
aniline. The dark solution is then filtered and alcohol and ether added, when
diazobenzene nitrate is precipitated as a crystalline mass. Or, potassium nitrite
may be allowed to act upon aniline nitrate (p. 629). The solid salt is more easily
obtained by using alcohol and amyl nitrite (p. 632).

Diazobenzene nitrate forms long, colorless needles, and when
dry is rather stable. It browns in moist air and decomposes rapidly.
When heated it explodes with violence. '

Diazobenzene sulphate, CgHj.Nj.SO^H, is similarly obtained from aniline sul-
phate. It is advisable to add sulphuric acid (diluted with 2 volumes of water),
alcohol (3 volumes) and then ether to the solution of diazobenzene nitrate. The
sulphate then separates out at the bottom of the aqueous solution. After a second
treatment with alcohol and ether,-and evaporation under an air pump, it can be
obtained crystalline. It consists of colorless needles or prisms, which dissolve
readily in water. It explodes at 100°. It is, perhaps, also better in this case to
use alcohol and amyl nitrite for the precipitation of the salt (p. 632).

Diazobenzene Su/phom'c Acid, C^Ji^.N^.SO^li. Its potassium salt is obtained
by adding diazobenzene nitrate to a cold, neutral or feebly alkaline' solution of
potassium sulphite. The liquid solidifies to a crystalline mass of CgH5.N2.SO3K
[Annalen, 190, 73). Acid potassium sulphite forms potassium benzene-hydra-
zine-sulphonate, CgHj.Nj.Hj.SOgK.

Diazobenzene Bromide, CgHg.Nj^r, separates in white laminae, if bromine be
added to the ethereal solution of diazo-amido-benzene. Tribrom-aniline remains
in solution. Ether precipitates the bromide from its alcoholic solution.

Diazobenzene Perbromide, C5H5.N2Brg, is precipitated from the aqueous solu-
tion of diazobenzene nitrate or sulphate, by bromine in HBr-acid or NaBr. It
is a dark-brown oil, which quickly becomes crystalline. It is insoluble in water
and ether, and crystallizes from cold alcohol in yellow laminae. Continued wash-
ing with ether converts it into the diazo-bromide.
f The Platinum Double Salt, (CgHj.NjC^j.PtCl^, is precipitated in yellow

DIAZO-AMIDO-BENZENE. 637

prisms on adding a hydrocUoric acid solution of PtCl^ to the solution of the
nitrate or sulphate. It is slightly soluble in water, and deflagrates when heated.

Potassium Diazobenzene, CgHj.Nj.OK, is separated, as a yellow liquid, from
diazobenzene nitrate, by concentrated caustic potash. It crystallizes when evapo-
rated on the water-bath, forming white, pearly/ leaflets, which readily dissolve in
water and alcohol; the aqueous solution decomposes quickly.

Silver Diazobenzene, CgH5.N2.OAg, is precipitated as a gray compound from
the potassium salt by silver nitrate. It explodes very violently.

The compounds with mercury, lead, zinc, and other metals, ^re formed in a
similar manner.

Acetic acid liberates diazobenzene (p. 630) from the potassium salt in the form
of a heavy oil. It decomposes at once.

Diazo-amido-benzene, CsHs.Nj.NH.CeHj (p. 634), is ob-
tained by the action of nitrous acid on the alcoholic solution of
aniline ; by mixing diazobenzene nitrate with aniline, and by pour-
ing a slightly alkaline sodium nitrite solution upon aniline hydro-
chloride (p. 630).

Dissolve aniline in alcohol (6-10 volumes), cool and conduct nitrous acid into
the solution until a portion crystallizes on evaporation. The solution is then
poured into water. A dark oil separates and soon becomes crystalline. It is
washed out with cold, and then crystallized from hot alcohol.

Another method consists in adding sodium- nitrite (l molecule), and then sodium-
acetate {Benchte, 17, 641 ; 20, 1581) to the hydrochloric acid (3 molecules) solu-
tion of aniline (2 molecules). Caustic soda forms amido-azobenzene at once. Or
dissolve 50 parts of aniline in 15 parts of fuming sulphuric acid and 1500 parts of
water. To this solution add sodium nitrite, when the temperature of the liquid is
25-30° {Berichte, 19, 1953)-

Diazo-amidobenzene consists of golden -yellow, shining laminae
or prisms. It is insoluble in water, sparingly soluble in cold, but
readily in hot alcohol, ether and benzene. It melts at 98°, and
then explodes.

It does not combine with acids, although it forms a double salt (Ci^HjjNj.
HCl)2.PtCl4, with hydrochloric acid and PtCl^. It crystallizes in reddish needles.
When the alcoholic solution is mixed with silver nitrate, the compound, CgHj.
NjNAg.CgHj, separates in reddish needles.

When the alcoholic solution stands, especially in the presence of a little aniline-
hydrochloride, the diazo-amidobenzene sustains an interesting transposition, result-
ing in the production of amido-azobenzene (p. 641).

Substituted anilines, «.^., C^H^Br.NHj, act with nitrous acid just the same as
aniline. They yield perfectly analogous diazo compounds.

Free diazo-chlor- and diazo-brom-benzene, CjH^Br.Nj.OH (p. 630), are crys-
talline compounds. They have not been analyzed because of their instability.
Higher substituted anilines, such as trinitro-aniline, CgH2(N02)3.NH2, cannot
form diazo-derivatives.

The aniline homologues, toluidine, xylidine, yield perfectly analogous diazo- and
diazo-amido-compounds with perfectly similar properties. Thus.thethree toluidines
(ortho-, meta- and para-) yield three corresponding isomeric diazotoluidines : —

C,H,(CH3)NH2 give C,H,(CH3).N2X.

638 ORGANIC CHEMISTRY.

The para-variety of the three diazo-amido toluenes, Q.^^i^Yi^.'^^^i^.C^^.
CH 3 , is alone stable. The ortho- and raeta-forms (from ortho- and raeta-toluidine)
immediately pass into amido- azo-derivatives.

It is strange that the mixed diazo-amido-compounds, which, according to their
mode of formation, should be different, are in fact identical. Thus, diazo-benzene-
amido-brom-benzene, CsHj.Nj.NH.CgHjBr, from diazobenzene and brom-ani-
line, is identical with diazobrombenzene-amidobenzene, CjH4Br.N2.NH.CgH5,
from diazobrombenzene and aniline. The following are also identical : —

CgH5.N2.NH.C6H4.CH3 and {CH3)C8H4.N2.NH.CeH5.

Diazobenzene-amido toluene. Diazotoluene-amidobenzene,

CgH5.N2.NH.CsH4.CO2H and (C02H)CjH4.N2.NH.C5H5.

Diazo-benzerie-amidobenzoic Diazobenzoic acid-amido

Acid. benzene.

This anomalous bfehavior can probably be accounted for by assuming that the
isomeric formulas are tautomeric, the hydrogen atom oscillating from the imide- to
the diazo-group (p. 54). Another conception allows but one of the formulas to the
two compounds ; according to this, the diazo-group and the amido-group transpose
themselves, the former always, however, entering the para-pOsition (Berichte, 19,
3239) :—

CgH5.N2.NH.C6H4.CH3 yields CgH5.NH.N2.CgH4.CH3.

{'> 4). . . , , (i. 4).

Diazobenzene->-amido- Amidobenzene-/-diazo-

toluene. toluene.

Experiments instituted to settle this question, have given contradictory results
(Berichte, 20, 3004 ; 21, 1020). The results with phenyl-cyanate are probably
more correct (p. 613). This reagent combines with the diazo-amido compounds,
and yields diazo-benzene-diphenyl ureas: —

CgH5.N2.NH.CgH5 + CO:N.CgH5 = CgH5.N2.N/^5^jJjj^^jj^.

Diazobenzene-diphenyl Urea.

The latter decompose into diazobenzene (its decomposition products) and di-
phenyl ureas : —

CeH5.N2.N(Ca^^5^^^^^ + H2O = C,H5,0H + N2 + Co/^g.CgH,

The mixed diazo-amido compounds react similarly. The product obtained by
the action of diazobenzene upon paratoluidine, and ^-diazotoluene upon aniline,
yields with phenylcyanate a compound that, on decomposing, forms phenyl-tolyl-
urea. It is, therefore, diazobenzene-amido-toluene, CgHj.Nj.NH.C,!!,. The de-
composition of itS'phenylcyanate may be expressed as follows : —

C,H,N2N<;^vf^'H.CgH5 + HP = CgH^.OH + N2 + Co(NH-C,H,_

Diazobenzene-tolyl-phenyl Urea. Phenyl-tolyl Urea.

Other mixed diazo-amido-derivatives behave similarly. They are distinct bodies;
in their formation a transposition occurs, in that the imide group attaches itself to
the more negative radical (Goldschmidt, Berichte, 21, I016 ; 22, 2578).

On mixing diazo-benzene salts with primary and secondary amines, the products
are »?«>«■(/ diazo-amido compounds containing radicals of the paraffin series.

Diazobenzene-ethylamine, CgH5.N2.NH.C,^H5, and Diazobenzene-dime-
thylamine, CgH5.N2.N(CH3)2, are yellow oils, that form very unstable salts with
acids.

DIAZO-AMIDO-BENZENE. 639

Bis-diazo-amiilo-derivaHves are obtained by further action of diazobenzene salts
upon the compounds with primary amines, e. g., (C5H5.N2)jN.CH3, bis-diazo-ben-
zene-methylamine ( Berichte, 22, 942).

^zWzazo-compounds (p. 626) are formed from the diamines of the para- and
meta-series : —

Para- and Meta. _/S- and wz-Bisdiazo-

chlorides.

These are also termed /^frazo-compounds. The ortho-diamines, on the other hand,
yield the azimido-derivatives (see below).

Diazimido- or Triazo-compounds, CgHj.Nj. These are derivatives of azo-

imide, HNC 11 , recently discovered {Berichle, 23, 3023). They are produced :

(i) By the action of aqueous ammonia upon diazobenzene perbromides : —

C.H^.N^.Br^ + 4NH3 = CsH^.N^.N + 3NH,Br.

(2) By the action of hydroxylarriine upon diazobenzene sulphate : —

CeH5.N2.SO,H + NH.OH = CeH^.Ns + Hp + SO^H,;

and most readily and easily by the action of sodium nitrite upon the hydrochloric
acid solution of phenylhydrazine, when the nitrosophenylhydrazine first produced
sustains decomposition (Fischer, Annalen, igo, 92) : —

CeH,.N( = CeH,N<; || + H,0.

Benzenediazimide,

Triazobenzenes, like benzene-diazimide or triazo-benzene , CgHj.Nj, are yellow
oils, insoluble in water. Their odor is stupefying. They are volatile in a vacuum
and in a current of steam. They explode at the ordinary pressure, if heated. They
are decomposed into Ni, and chloranilines when boiled with hydrochloric acid {Be-
rickte, 19, 313).

Substituted diazobenzenes yield analogous triazo-compounds. Thus, nitro-diazo-

benzene bromide, C5H^(N02).N2Br, yields amido-triazobenzene, CgH^^j^^ ^'

which, by diazotizing, etc., forms Bistriazobenzene, CjH^^" j,', or Hexazoben-

zene. White leaflets, melting at 83°. It explodes violently, if heated to a higher
temperature {Berickte, 21, 1559)-

Nitrous acid converts hydrazobenzene sulphonic acid into Triazobenzene sul-
fhonic acid {Berichle, 21, 3409) : —

r w /SO3H , TTTuo — r H /°^j" .0- 2H O

Another peculiar formation is that of the triazo-compounds by the action of diazo-
salts upon hydrazines (Berichte, 20, 1528 ; 21, 34IS)-

640 ORGANIC CHEMISTRY.

The Aztmzi/o-compoxmds are isomeric with the diazimido-derivatives. They
are produced by the action of nitrous acid upon ortho-phenylene diamines : —

Azimidobenzene.

They behave lilce secondary bases ; their imide hydrogen can be replaced by
metals, acid radicals and alkyls. The alkyl derivatives can combine further with
alkyl iodides and yield ammonium compounds (Zincke, jBerichle,z2, Ref. 139;
23, Ref. 105).

Azimido benzene, CgH^iNgH, isomeric with diazimido- or triazo-benzene, Cg Hj.
N3, forms white needles, melting at 98.5°.

Pseudo-azimides are intimately related to the azimido-derlvatives. They are
formed by oxidizing the ortho-amido-azocompounds with chromic acid (Berickte,
23, 106, 1315, 1844) :—

C,H / + O = C,H / I )N.C,H,. + H,0.

^'Amido-azo-toluene. Pseudoazimido-toluene.

Benzoylazimide, CjH5.CO.N3 (Triazobenzoyl), is formed by the action of ni-
trous acid upon benzoyl hydrazine, CgHj.CO.NH.NHj. When decomposed, it
yields benzoic acid and the remarkable compound known as

Azoimide, HNiNj, Hydrazoic Acid. This is perfectly analogous to the haloid
acids. It conducts itself similarly (Curtius, Berickte, 23, 3023).

AZO-COMPOUNDS. '

Like the diazo-derivatives, these contain a group, consisting of
two nitrogen atoms ; in the former the Nj-group is combined with
only one benzene nucleus ; here it is attached on either side to
benzene nuclei : —

CeH,N,X. C,H,.N,.CeH,.

Diazo-compounds. Azo-compounds.

In consequence, they are far more stable than the former, and do
not react with the elimination of nitrogen. They are classified as
azoxy-, azo-, and hydrazo-compounds. They constitute, as it were,
a transition from the nitro- to the amido-derivatives : —

CeHs

•N,

CsHs

.N

CeH^ .

.NO,.

1 )o

II

Nitrobenzene.

Azoxyb

.n/

CeHj

.N

tenzene.

Azobenzene.

CaH,

.NH

CeHs .

.NH,.

CeHs

.NH

Amidobenzene.

Hydrazobenzene.

AZO-COMPOUNDS. 641

They are obtained according to the following methods : —

1. By reduction of the nitro-compounds in alkaline solution.
Amido-derivatives are formed in acid solutions. By moderated
reduction with an alcoholic potassium hydroxide solution (Zinin),
or zinc dust and ammonia, az^a^y-compounds are produced at first
(the alcohol is oxidized to aldehyde) : —

2CeH5.NO, = (CeH,),N,0 + 30.

Stronger reducing agents (sodium amalgam in alcoholic solution,
zinc dust with sodium hydroxide) immediately form the azo- and hy-
rfrazt^-derivatives. In many cases the action of SnClj in equivalent
quantity, dissolved in NaOH (2 molecules SnClj for i molecule of
the nitro-compound), is well adapted for the preparation of the
azo-compounds (Witt, Berichte, 18, 2912). (All the nitrobenzene
compounds, excepting nitronaphthalene, react similarly).

2. By the oxidation of the primary amido-derivatives in alkaline solution with
potassium permanganate or potassium ferricyanide (Berichte, 9, 2098). Energetic
reducing agents convert all the azo-derivatives into amidobodies (p. 645).

3. By the action of sodium or potassium upon primary amido-compounds.
Sodium amido-derivatives result and the oxygen of the air oxidizes them to azo-
derivatives {Berichte, 10, 1802) : —

2C,H5.NHK + O, = (C,H5),N2 + 2KOH.

Similarly, bromaniline yields azobenzene, as the bromine is reduced by the
nascent hydrogen. The action of CgHj.NCI, upon aniline produces azobenzene
(Berichte, 16, 1048).

4. By the action of the nitroso-compounds upon the primary amines (see
Nitrosophenol) : —

CeH5.NHj+ ON.C6H4.0H= CgHj.NiN.CsH^.OH + H^O.

Reducing agents (H2S) also further change the azoxy- to azo- and
hydrazo-compounds ; conversely, when the hydrazo- are oxidized
(even in the air) they become azo-compounds.

The azoxy- and azo-derivatives are solids with a yellow to brown
color, and do not unite with acids ; the hydrazo-bodies are color-
less and when in alcoholic solution, are easily changed by acids to
isomeric diamido-diphenyls. By the action of stannous chloride
and a slight quantity of sulphuric acid upon the alcoholic solu-
tion of the azo-bodies, the latter can be directly converted into
benzidines (Berichte, 19, 2970). Because of their stability, the
azo-compounds can be directly chlorinated, nitrated and sulpho-
nated.

On reducing the nitro-azo-derivatives, we obtain the amido-azo
compounds : —

CeHs.Nj.C.H^.NO, yields CeH5.N,.C,H,.NH,.

Nitro-azobenzene. Amido-azobenzene.

54

642 ORGANIC CHEMISTRY.

These are also obtained from the diazo-compounds by peculiar
reactions: —

(i) By direct transposition of the diazoamido-compounds (p.

63s) •■—

CeHj.Nj.NH.CeHs forms CeHj.Nj.CeH^.NHj.

Diazoamidobenzene. Amido-azobenzene.

In the case of diazoamido-benzene, this transposition occurs on
standing with alcohol, but more readily by the action of a slight
quantity of aniline hydrochloride {Berichte, 19, Ref. 24).

The group NH.CgHj is eliminated from the diazo-compound, and the diazo-
group, Nj, attaches itself to the benzene nucleus of the aniline : —

CeH,.N,.NH.CeH5+ CgH5.NH,= C,H5.N,.C6H,.NH, + CeHj.NHj.
a b b a

As aniline is regenerated here, a very slight quantity of it suffices to transform
the diazo- into the azo-compound. That the reaction indeed occurs as indicated,
is verified by the knowledge that other (homologous) amido-componnds act simi-
larly upon the diazo-amido-derivatives. Thus we obtain azo-derivatives from diazo-
amido-toluene, by the action of the salts of meta- and ortho-toluidine (Berichte,
10, 664 and 1156) : —

Para. Para. Ortho or meta. Para. Ortho or meta.

+ NH,.CsH,.CH3.

Para.

This would go to prove that the reaction only occurs readily, if in the reacting
amido-compound the position in the benzene nucleus adjacent to the amido group
in the para place be unoccupied ; the diazo group, Nj, then arranges itself in the
para-position referred to the NHj of the amido-compound.

This explains, too, why only diazoamido compounds are obtained from para-
toluidine by nitrous acid, whereas the orthb- and meta toluidines (in which the
para-position is free) immediately yield the amido-azo derivatives (p. 638), because
the diazoamido-bodies first produced can immediately transpose themselves. It
was formerly thought, that in the production of azoamido-compounds, the diazo-
group could invariably only enter the /ara-pqsition (referred to the amido-group.)
This, however, occurs only with special ease in alcoholic solution. On heating
diazoamido-paratoluene, dissolved in fused paratoluidine, to 65° with paratoluidine
hydrochloride, a transposition will also take place with formation oi ortho amido-azo-
toluene,Caiii{CYi^).^^.C^U^{Cn^).l<iU.^ (melting at 118°), as the diazo-group
enters the orMo- position (referred to amido.group) \Berichte, 17, 77). The diazo
compounds behave in a similar manner with phenols (p. 643).

Diazobenzene-ethylamine and dimethylamine (p. 638) react like the diazo-amido-
compounds with aniline hydrochloride, the alkylamines breaking off at the same
time : —

C,H,.N,.N(CH3), + CeH,.NH, = CeH5.N,.CeH,.NH, + NH(CH3)2.

(2) By the action of the diazo-compounds upon the tertiary ani-

AZO-COMPOUNDS. 643

lines (diazoamido-derivatives first result from the primary and sec-
ondary anilines, p. 635) : —

CeH^.N^-NOs + C,H,.N{CH3)j = CeH5.N,.CeH,.N{CH3), + NO3H.

In this reaction also, the Nj-group enters the position para with reference to
the amido-group, and therefore dimethyl paratoluidine does not react (Berichie,
10, 526). Paradiazobenzene sulphonic acid acts directly on the HCl-anilines,
forming sulpho-acids of the amidoazo-compounds (Berichte, 15, 2184).

(3) By the action of the diazo-compounds upon the diamido-
derivatives of the meta-series (p. 636), those of the ortho- and para-
places not reacting {Berichte, 10, 389 and 654) : —

r H TJ 'NT) 4_r H /^"jl ) r T^r N r h /■^"2( ) _i_ mo h

The resulting compounds are dyestuffs, called chrysotdines (p. 648),
varying in color from orange to brown.

The most recent research would seem to indicate that the amido-azo-compounds
of the ortho-series are quinone-derivatives (similar to the so-called nitrospphenols),
and, indeed, hydrazones of quinon-imides. It is probably an instance of tauto-
merism of formulas (Berichte, 23, 497) : —

NH
C H /NHj _ c H ■^^'^ or C H / I

ff-Amido-azobenzene, tf-Quinon-imide-phenyl-hydrazone.

Arguments favoring this view, are the production of pseudo- azimides by the oxi-
dation of the «-amido-azo-benzenes (p. 640) and the reduction of the o-diazo-azo-
benzenes to diazo-hydrides (Berichte, 20, 1176).

Probably, also, the oxy-azo- compounds of the ortho-series should be regarded as
hydrazones of the quinones {^Berichte, 22, 3234 ; 23, 487) : —

C H /°^ - C H ^"O

<7-Oxy-a2obenzene. Quinone-phenyl Hydrazone.

The diazo-derivatives react analogously with the phenols, forming
oxyazo-compounds. With the monovalent phenols we have : —

CeH^.N^.NOe + CsH^-OH = C6H5.Nj.CeH,.OH -f HNO, ;

with the divalent phenols of the meta series (as resorcinol) : —

CeH5.N,.N03 + C,H /gH_CeH5.N,.CeH3/gg ^ jjNO,;

(1,3). (-.S)-

and with phenol-sulphonic acids and amidophenols of the mela
series : —

C,H,.N,N03+C,H,(0H^ = C,H,.N,C,H3/05h + HNO3.

644 ORGANIC CHEMISTRY.

They are also produced on heating the diazo-amido-benzenes with
phenols, and with resorcinol {Berichte, 20, 372, 904 and 1577 ; 21,
1112) : —

C6H5.N,.NH.CeH5 + C5H5.OH =C6H5.N,.C,H,.OH + CeHj.NH,.

Or, by the molecular rearrangement induced by heating azoxyben-
zenes with sulphuric acid (see oxy-azo-benzene, p. 646) : —

CeH^.N

I )0 yields CeHs.N^.CeH^ OH.
CeHj.N/ '

Azoxy-benzene. Oxy-azo-benzene.

The sulpho-acids of the azo-compounds (see above) can also be
prepared by heating the latter with concentrated or fuming sul-
phuric acid (by directly sulphonating them — see benzene sulphonic
acid). An easier course consists in letting diazo compounds act
upon phenol sulphonic or amido-sulphonic acids, or conversely by
combining diazobenzene sulphonic acids and amines or phenols : —

r H / 2 \ 4- r H OH — r H /Nj.CsH^.OH

^""lySOg/ + ^6"5-'J" — "-6J^4\S03H.
Diazobenzene Sul- Phenol. Oxy-azobenzene Sulphonic

phonic Acid. Acid.

These oxyazo- and amido-azo-sulphonic acids are called tropao-
lines; many of them are applied as dyestuffs.

The diazo-compounds act on the phenols in aqueous solution, but more readily
when alkali is present (diazobenzene sulphate forms only phenyl ether or phenyl
oxide, (CgH5)20, with aqueous phenol). Ordinarily the phenol derivative is dis-
solved in dilute alkalies and the aqueous diazo- chloride added. Occasionally it is
advisable to apply sodium acetate instead of caustic alkalies [Berichte, 17, 641).
Variations occur in the reaction sometimes, attributable to the quantity of alkali,
whether it be in excess or in equivalent amount [Berichte, 17, 878). In the case
of diazo-compounds and mono- and di-valent phenols two isomeric products, a
and /3, may arise — products soluble and insoluble in alkali (Berichte, 17, 877),
(see Dibenzene-disazoresorcinol, p. 647).

As in the amido-compounds, so in the phenols, the entering diazo-group prefers
and assumes the para position with reference to the hydroxyl group (p. 642) ; in
the divalent phenols, like resorcinol, it takes the para-position referred to the one
hydroxyl. When the /i-position is occupied the diazo-group can assume the ortho-
position, e. g., in /-cresol, /-phenolsulphonic acid and /3-naphthol {Berichte, 17,
876; 21, Ref. 814).

The amido-azo- and oxy-azo-compounds are yellow to brown in
color, readily soluble in alcohol, and usually crystalline. The salts
with acids and alkalies constitute what are known technically as azo-
dyestuffs (p. 650). While the colored azo-compounds (having the
chromophorus atomic group N:=N) are not themselves dyes, they
do acquire, by the entrance of the chromogenic, salt-forming groups
OH and NHj, the character of dyestuffs (Witt, Berichte, 9, 552).
They are decolorized by reducing agents (tin and hydrochloric

AZOXYBENZENE. 645

acid, zinc chloride, boiling with zinc dust, or upon digestion with
ammonium sulphide), taking up four hydrogen atoms and being
resolved into two amido-compounds. The azo-group, N=N, de-
composes, each nitrogen atom remaining attached as NH^ to a
benzene nucleus : —

CeHs.N^.CeH.NH^ + 2H, = CeH^.NH, + CeH,(NH,),.

Thus, /-oxy-azobenzene is resolved into aniline and /-amido-
phenol. This reaction, therefore, may serve for the determination
of the constitution of azo-compounds (^(j^^zV^/^, 21, 3471). Such
a decomposition occasionally takes place by heating with hydro-
chloric acid, indulines being simultaneously produced {Berichte, 17,
395). Consult Berichte, 15, 2812, upon the nomenclature of the
azo-derivatives.

Nitrous acid converts the amido-azo-derivatives (like the amido-derivatives) into
diazo-, «. ^., CgH5.N2.CgH4.N2Cl, azobenzene diazochloride, which, like simple
diazo- and amido-derivatives, act on the phenols, forming so-called tetrazo-com-
pounds, e. g. : —

CgH,.N2.CeH,.N2.CgH,.OH. CgH,,.N2.CeH,.N2.CeH,(OH)2.

Azobenzene-azo-phenol. Azobenzene-azo-resorcinol.

Such compounds can also be obtained by a second introduction of two molecules
of a diazo-compound into phenols (resorcinol), and are also called diazo-deriva-
lives : —

CgH :N2/^«^^^(°")^ = C,H3.N2.C,H2(OH)2.N2.C,H,.

Dioenzene-diazo- Benzene-azo-resorcinol-azo-benzene.

Resorcinol.

Analogous compounds are also obtained from the anilines, and are called azotriple
bases {^Berickte, 16, 2028).

Another course, that may be pursued in obtaining the tetrazo-derivatives, em ■
ploys the phenylene-diamines, C5H4(NH2)2, as points of departure, converting
one and then the other amido- into a diazo group, and finally combining the pro-
duct with phenols. Violet and blue azo-derivatives [Berichte, 17, 344, 1350; 21,
Ref. 268) are produced in this manner.

The tetrazo-compounds from benzidine and tolidine are especially important
(p. 652).

Azoxybenzene, (C6H5)2N20, Azoxybenzide, is obtained by
the reduction of nitrobenzene, or by the oxidation of amido-ben-
zene (p. 641), the first being the preferable method.

Add 30 parts of pure nitrobenzene to a solution of 10 parts sodium in 250 parts
methyl alcohol and boil for five or six hours, employing a return condenser. The
unused methyl alcohol is distilled off and the residue washed with water (Berichte,
15, 866, 1515). Or, I part of nitrobenzene is added to the boiling solution of I
part KOH and 9 parts alcohol.

646 ORGANIC CHEMISTRY.

Azoxybenzene forms long, yellow needles, easily soluble in alco-
hol and ether, but not in water. It melts at 36°, and decomposes
into azobenzene and aniline when distilled. It is converted into
oxyazobenzene by digestion with sulphuric acid.

m-Dinitroazoxybenzene, {^O^C^'R^^^O.Q^^^^i^O^, is produced when
sodium methylate acts upon »8dinitrobenzene, C8H4(N02)2. It melts at 141°
[Berickte, 18, 2551). m-Diamidoazoxybenzene,{^}i^)C^H^.^^O.C^^^M'ii^,
azoxyaniline, is obtained by the reduction of »-nitraniline with zinc dust and
caustic soda {Berickte, 21, Ref. 766). The nitration of azoxybenzene produces
two trinitroazoxybenzenes, which form trinitro-azobenzenes by partial reduction
{Berickte, 23, Ref. 104).

Azobenzene, (CeHj^Na, Azobenzide, is formed by the action
of sodium amalgam upon the alcoholic solution of nitrobenzene,
and by boiling nitrobenzene with alcoholic potash.

A simpler, procedure is to distil azoxybenzene with iron filings, or to reduce
nitrobenzene with zinc dust and caustic potash {Annalen, 207, 329). Or, nitro-
benzene is added to a solution of stannous chloride (calculated amount) in sodium
hydroxide (p. 641). >

Azobenzene forms orange-red, rhombic crystals, readily soluble
in alcohol and ether, but sparingly soluble in water. It melts at
68°, and distils at 293° ; its vapor density confirms the molecular
formula, Ci^HioNj. It is converted into benzidine by tin and
hydrochloric acid. When it is heated with ammonium bisulphite
and alcohol under pressure benzidine sulphaminic acid, NHa-CeH^.
QH^.NH.SOsH (p. 650) results {Berickte, 18, 1481).

The nitration of azobenzene produces p-Nitro-azo-benzene, CgH^.Nj.CgH,,.
(NOj), melting at 137°; by reduction this yields /-amido-azo-benzene (p. 647).
The nitration of the glacial acetic acid solution yields o- nitro-azo-benzene, melting
at 127° {Berickte, 18, 2157; Ref. 441). Energetic nitration gives rise to various
dinitro- and trinitro-azo-benzenes {ibid).

p-Dinitroazobenzene, NOj.CgH^.Nj.CjH^.NOj, melts at 206°, and is reduced
by ammonium sulphide to /-diamido-azo-benzene (p. 648) and to diphenine (p.
650). m-Dinitroazobenzene is an oil; ammonium sulphide changes it to m-
diamido-azo-benzene {Berickte, 18, Ref. 627) ; when this decomposes /w-pheny-
lene diamine results.

A diniiro-azobenzene,mAtm% at 117°, has been obtained by the oxidation of
dinitrohydrazobenzene {Berickte, 21, Ref. 400; 22, Ref. 744).

Trinitroazobenzenes,C-y^'il^{^0^)^^,'\i3.y& been prepared by the partial reduc-
tion of the two tri-nitro-azoxybenzenes.

Nitrolic Acids, of unknown constitution, were formed in the reduction of
nitrazobenzenes with ammonium sulphide in the presence of caustic potash {Be-
rickte, 18, 1136; Ref. 628).

^-Oxyazobenzene, C5H5.N2.CgH4(OH),'Benzeneazophenol, is obtained on
digesting diazobenzene nitrate with barium carbonate ; by mixing the former with
a solution of sodium phenol ; by the action ,of para-nitrosophenol upon aniline
acetate (p. 641), and by the action of concentrated sulphuric acid upon azoxy-

AMIDO-AZO-BENZENE. 647

benzene {Berichte, 14, 261 7), as well as by heating together phenol and diazoamido-
benzene. It crystallizes in orange-yellow needles, and melts at 148°-

Those oxyazo-,compounds, containing a hydroxyl group in the ortho-position,
with reference to the azo-group, are very probably quino-hydrazones. CSj, on
application of heat causes them to decompose, thus forming carbamido-thiophenols
{Berichte, 22, 3233).

Dioxyazobenzenes : /-Azophenol, C5H<(OH).N2.C.H4(OH), results: by
fusing para-, nitro- and nitroso-phenol with caustic potash ; by the union of diazo-
phenol nitrate with phenol, and from para-oxyazobenzene sulphonic acid {Berichte,
15, 3037). It consists of light brown crystals, and melts at 204°. Benzene-azo-
resorcinol, CjHj.Nj. 0^113(011)2, is produced by adding diazobenzene nitrate
or chloride to resorcinol in aqueous or alkaline solution. It forms red needles,
melts at 168°, and dissolves with a yellowish-red color in alkalies. Dibenzene-
diazo-resorcinol [y, insoluble in alkalies) forms at the same time ; it results from
the decomposition of diamido-resorcinol {Berichte, 17, 880).

The further action of a second molecule of diazobenzene chloride upon benzene-
azo-resorcinol in alkaline solution, produces two isomeric Dibenzene-disazo-

resorcinols, p^tt5't^2^C.Hj,(OH)2, a and /?. The oi-compound is easily solu-

ble in aqueous alkalies, forms red needles, melts at 214°, and dissolves in HjSO^
with a red color. The /3-compound is insoluble in alkalies and dissolves in H ^ SO^
with a dark blue color {Berichte, 15, 2816; 17, 880).

Compounds soluble and insoluble in sdkalies are almost invariably produced by
the union of diazo-derivatives with phenols. In the insoluble ones the N^-group
seems almost always to occupy the ortho-position as compared with hydroxyl
{Berichte, 16, 2862).

The azobenzene-azo-resorcinols, CgHj;.N2.CjH^.Nj,.CgH3(OH)2, are iso-
meric with the benzene-disazo-resorcinols. They form in the action of the diazo-
chloride of amidoazo-benzene, CjHj.Nj.CgH^.NHj, upon resorcinol {Berichte,
15, 2817) (compare p. 645).

/J-Amido-azo-benzene, CeHs.Nj.CsH^.NHj, is obtained in the
reduction of nitro-azo-benzene with ammonium sulphide, and by
the molecular transposition of isomeric diazo-amido-benzene (p.
642).

It is best prepared by the action of a mixture of potassium nitrite (1 molecule)
and caustic potash upon aniline hydrochloride (2 molecules) ; the diazo-amido-
benzene first produced in the cold is transposed by digestion into amido-azo-ben-
zene (p. 642).

Or, freshly prepared, moist diazo-amido-benzene is dissolved in 2-3 parts ani-
line, y'j part aniline hydrochloride added, and the whole digested at 40° for an
hour, and then allowed to stand 24 hours, by which time the conversion into amido-
azo-benzene will be fully ended {Berichte, 19, 1953; 21, 1633).

Aniline hydrochloride (i molecule) can be dissolved in aniline (5-6 molecules),
and mixed at 30-40° with a concentrated solution of sodium nitrite (a little less
than one molecule) and digested from 1-2 hours at a temperature of 40°, when it
is finally allowed to stand undisturbed for 12 hours. The addition of an excess of
hydrochloric acid will cause a complete precipitation of the hydrochloride of amido-
azo-benzene {ibia).

It crystallizes from alcohol in yellow needles or prisms, melts at
123°, and boils above 360°. It forms crystalline salts with one

648 ORGANIC CHEMISTRY.

equivalent of acid ; these are yellow and violet colored, and impart
an intense yellow to silk and wool. The HCl-salt crystallizes from
hydrochloric acid in blue needles or scales. MnOj'and sulphuric
acid oxidize it to quinone. It is decomposed into para-diamido-
benzene and aniline by tin and hydrochloric acid, digestion with
ammonium sulphide, or boiling with hydrochloric acid (p. 645).

Commercial Aniline Yellow consists usually of amido-azo-benzene oxalate. The
so-called /i«V Yellow or Pure Yellowis, a mixture of amido-azo-benzene sulphonic
acids, and is prepared by the action of sulphuric acid on the amido azo-compound,
or by converting sulphanilic acid, CeH4(S03.H).NH2, into the diazo-corapound,
and then treating with aniline [BericAte, 22, 850).

Phenyl-^-amido-azo-benzene, C5H5.N2.C5Hj.NH.CjH5, is isomeric with
induline. It is produced from diazobenzene chloride and diphenylamine. It con-
sists of golden-yellow leaflets, melting at 82°. Its sulphonic acid is tropseoline 00
(p. 651).

Indulines are obtained on heating /-amido-azo-benzene or other /-amido-azo-
derivatives with aniline hydrochlorides, whereas the o-amido-azo-compounds yield
the eurhodines i^Berichie, 19, 441).

Nitrous acid converts HCl-amido-azobenzene into the diazo- chloride, C5H5.
Nj.CgHj.NjCl ; the diazo-grpup in this can be replaced by copper sulphate and
potassium cyanide. The resulting azo-benzene cyanide,, C5H5.N2.C5Hj.CN,
melts at 10° and is changed to azobenzene carboxylic acid, C5H5.N2-C6Hj.CO2H
{Berickte, ig, 3023), by boiling alkalies.

The disazo- or tetrazo-anilines, or phenols, result from the action of azo-
benzene diazo-chloride, C5H5.N5.C5H5.N2CI, upon aniUnes and phenols. Disazo-
benzene, C5H5.Nj.C5Hj.N2.C5H5, the basis of these derivatives, has been ob-
tained from its amido-compound. It is very similar to azo-benzene, and melts at
98° [Berickte, 21, 2145).

Diamido-azo-benzene, C12H12N4 = C5H5.N2.C5H3(NH2)2,
Benzene-azo-phenylene-diamine, is produced by the action of diazo-
benzene-nitrate upon meta-phenylene-diamine (p. 643), and con-
sists of yellow needles, melting at 117°. Its hydrochloric acid salt
occurs in trade under the name chrysoidine, and dyes orange-red.
Reduction changes it to aniline and unsymmetrical triamido-ben-
zene, C5H3(NH2)3.

Symmetrical /-Diamido-azo-benzene, H2N.C5Hj.N2.C5Hj.NH2, has been
prepared by reducing nitroacetanilide, N02.CgHj.NH.C2H30, with zinc dust and
alkali; also, from diazo-phenylene diamine, etc. [Berickte, 18, 1145), and by the
reduction of /-dinitroazobenzene (see above) [Berickte, 18, Ref. 628). It crys-
tallizes from alcohol in yellow needles, melting at 235°.

Its tetra-alkylic derivatives are the so-called Azylines. They are formed when
nitric oxide acts upon the tertiary anilines (dialkylanilines) [Berickte, 16, 2768J : —

2C5H5.NR, yield R2N.C5Hj.N2.CeHj.R2N,

and in the action of the diazo-compounds of dimethyl-/- phenylene diamine (p. 625)
upon tertiary anilines [Berickte, 18, 1 143) : —

(CH3)2N.C5nj.N2Cl -f C5H5N(CH3)2 =

(CH3)2N.C5Hj.N2.C5HjN(CH3)2 + HCl.

HYDRAZO-BENZENE. 649

The azylines are red, basic dyes, which dissolve in hydrochloric acid with a
purple-red and in acetic acid with an emerald-green color. By rfeduction (stan-
nous chloride, tin and hydrochloric acid) they yield two molecules of dialkylic
/■phenylene-diamine. They are decomposed when heated to 100° with alkyl
iodides (4 molecules) ; the products in this case are tetra-alkylic para-pheny-
lene-diamines.

Triamido-azo-benzene, Ci.HijNj = H,N.CeH,.N,.C,H3/^gi', is

formed when nitrous acid acts upon metaphenylene-diamine, C5Hj(NH2)2. At
first, by transformation of an amido-group, we obtain a diazo-compound, which
further reacts on a second molecule of the diamine. It forms salts with one, two
and three equivalents of the acids; of these the diacid are the most stable,
while water decomposes the triacid. Its hydrochloric acid salt is commercial
Phenylene Brown (Manchester-brown, Bismarck-brown), which is applied in dye-
ing cotton and coloring leather.

Azotoluenes, CHj.CsHi.Njj.CjHj.CHj.

These are obtained, like azobenzene, from the three nitrotoluenes by the action
of sodium amalgam or zinc dust in alkaline solution. Ortho- and me/a- azo-
toluene form red crystals ; the first melting at 137° and the latter at 55°. Para-
azotoluene crystallizes in golden yellow needles, melting at 143°.

The action of sodium methylate upon para.nitrotoluene produces diamidostil-
bene, C5H^(NHj).CH:CH.C5Hi(NH2) {Berichte, 19, 3237).

Of the three diazoamidotoluenes, CjH^.CHg.N^.NH.CgHjJCHj), the ortho- and
meta- rearrange themselves into the corresponding amidoazotoluenes while the
para-derivative remains unaltered (seep. 642). The azo-group takes up the para
position with reference to the amido-group : —

CH3.CeH,.NH, yields CH3.CeH,.N,.C5H3.(CH3)NH,.

tf-ToIuidine. (2, i.) (i, 3, 4.)

CH3.CH,.NH, yields CH3.CeH,.N,.C,H3.(CH3).NH,.

?«-Toluidine. (3, i.) (i, 2, 4.)

Amidoazotoluene, from o-toluidine, forms yellow leaflets. It melts at 100°.
Amidoazotoluene, from »2-toluidine, melts at 80°. In paratoluidine the para-
position is occupied ; the azo-group therefore takes up the o/-//5o-position with
reference to the amido group. The resulting ortho-amidoazotoluene, with the
amido- and azo-groups, in the ortho-position, melts at 1 18°.

Ortho-amidoazo-derivatives like these exhibit a varying deportment. Chromic
acid oxidizes them to pseudoazo-imido compounds, and when heated with aniline
they yield eurhodines.

See Berichte, 23, 1738 for azoxy toluenes.

Hydrazo-benzene, C^Hi.Nj = QHs.NH.NH.QHj (p. 640),
is obtained by the action of HjS and ammonia upon the alcoholic
solution of azo-benzene, or by boiling the latter with zinc dust and
alcohol. It is readily soluble in alcohol and ether, crystallizes in
colorless plates, has an odor resembling that of camphor, melts at
131°, and further decomposes into azo-benzene and aniline. When
its alcoholic solution is exposed to the air it oxidizes to azo-ben-
zene. Hydrazobenzene (like phenylhydrazine) unites with alde-
hydes on heating, to form compounds known as hydrazoines.

650 ORGANIC CHEMISTRY.

The henzsddehyde derivsitive, Benz/iydrazoine, CJi^.CH./^'^'-ri^,

melts at 55° {Berichte, 19, 2239). It also unites with acetoacetic
ester and acetone-dicarboxylic esters, forming pyrazole derivatives.
It does not form salts with acids, but concentrated mineral acids
occasion in it an interesting transposition, resulting in the appear-
ance of the isomeric, basic benzidine (diamido-diphenyl) : —

C5H5.NH.NH.CgH5 forms NHj.CjH^.CjH^.NH^.

Derivatives of benzidine are produced when it is heated with organic acids
{Berichte, 17, 1 181). In benzidine the union of the benzene groups occurs in
the two para-positions. With benzidine (especially in the warm) there is also
produced isomeric o-/-diamido-diphenyl, C5H^.NH2(i, 4)

CeH,.NH,(i, 2)
Other hydrazo- compounds are similarly converted into dlphenyl derivatives, but
usually these are only such that have the para-positions, with reference to the
imide groups, free. Thus, 0- and ff2-hydrazotoluene yield the corresponding toli-
dines (diamidoditolyl derivatives) : —

CHj.CgHj.NH CH3.C5H3.NH2

I yield I

CHj.CgH^.NH CH3 C1.H3.NH2

Ortho and meta. Tolidine.

while/ hydrazotoluene is decomposed by strong acids. The para-azo-compounds,
however, can also be directly changed to diphenyl derivatives by the action of
stannous chloride and sulphuric acid (Berichte, 17, 463 ; 19, 2970).

Dinitrohydrazo-benzenes, C5H3(N02)2.NH.NH.C|jH5. Two isomerides
have been obtained by acting upon dinitrochlorbenzene with phenylhydrazine
{Berichte, 21, Ref 571).

/-Diamidohydrazobenzene, C5Hj(NH2).NH.NH.CeH4(NH2) = Cj^H^N^,
formerly called diphenine, results from the action of ammonium sulphide upon
para-dinitro-azo-benzene {Berichte, 18, 1 136). It consists of yellow crystals,
melts at 145°, and yields red colored salts with acids. Heated with ammonium
sulphide it breaks up into 2 molecules of meta-diphenylenediamine. Hydrazo-
benzene-disulphonic Acid, Q.^^^^.'i^^.l^Q)^)^, has been obtained by the reduc-
tion of OT-nitrobenzene sulphonic acid. Hydrochloric acid converts it into ben-
zidine disulphonic acid {Berichte, 21, Ref. 323 ; 23, 1053).

Hydrazotoluenes, CHj.CgH^.NH.NH.CgH^.CHg.

The three derivatives of this class are prepared from three azotoluenes (p. 649)
by the action of sodium amalgam, or by heating with ammonium sulphide. The
or^/io- compound melts at 165°; the meta is liquid, and the para consists of
large plates, melting at 124°.

Ortho- and meta-hydrazotoluene are readily changed by mineral acids into the
isomeric tolidines, NH2.C,Hs.C,Hs.NH2.

Azo-dyes.

Below are mentioned some of the innumerable, complicated azo-
compounds, which are applied technically as dyes. They are either
azo-amido-derivatives {azo-bases) which form salts with acids, or

AZO-DYES. 65 1

azo-phenol-compounds {azo-aeids) (p. 644), yielding salts with
bases. These salts represent the commercial dyes. In many cases
the sulphonic acids of the azo-bases and azo-acids (the iropcBolines,
p. 644) are better adapted for the purpose, as their alkali salts are
very stable, and usually afford dyes which dissolve readily in water.

The azo-dyes are made soluble by forming their alkaline bisulphite derivatives,
which are soluble in wat&. These are prepared by heating the azo-compounds
with sodium or potassium bisulphite in aqueous or alcoholic solution. On heating
these combinations with steam or dilute alkalies they split up into their compounds
and upon this behavior is based their application as colors for mordanted materials
[Berickte, 18, I479).

Arbitrary names are assigned these dyes, with the addition of the
letters Y (yellow), O (orange), and R (red), whose number approxi-
mately expresses the intensity of the color. They color wool and
silk directly, cotton after it has been mordanted. Recently violet
and blue azp-dyes have been successfully prepared (mainly tetra-
azo -compounds, p. 645).

Tropaeoline, O orR (Chrysoine, resorcin-yellow), CeHj(SOaH).N2.C5H3(OH)2,
Resorcin-azo-benzene sulphonic acid, is obtained from para-diazo-benzene sulphonic
acid and resorcinol {Berickte, n, 2195).

Tropseoline, 00 (Orange IV), C5Hj(SO.,H).N2.CeHj.NH.C8H5, Diphenyl-
amine-azo-benzene sulphonic acid, is obtained from diazobenzene sulphonic acid
and diphenylamine in alcoholic solution. It is used as an indicator in alkalimetry
[Berickte, i5, '989). By decomposition it yields sulphanilic acid, C5H^(NH2).
SO,H, and amido-diphenylamine (p. 603).

Helianthine, Methyl Orange (Orange III), C5Hi(S03H).N2.CeH^.N(CH3)2,
Dimethylaniline-azo-benzene-sulphonicacid, is formed from diazobenzene sulphonic
acid and dimethyl aniline {Berickte 10, 528). Consult Berickte, 17, 1490, for
another method of preparation. This and the analogous ethyl orange (from
diethyl aniline) serve as delicate indicators in alkalimetry; mineral acids convert
the alkaline orange-colored solution into a rose-red. COj, HjS and acetic acid do
not act on it in the cold (Chem. Zeit., vi, 1249; Berickte, 18, 3290). In decom-
position kelianthine yields sulphanilic acid and para-amido-dimethyl aniline (p.
601). Monometkyl- and Mono-ethyl Orange, C^^{^Ofi.):i^^.C^^:^^^(C^^),
are similarly prepared by the action of diazo-benzene-sulphonic acid upon methyl-
and ethyl-aniline. By its decomposition methyl- and ethyl-^-phenylene diamine,
H2N.C5H4.NH.CH3 {Berickte, 20, 924), are produced.

The azo-dyes obtained from the naphthalene derivatives, are of great value.

Tropaeoline OOO, No. I (Orange I), is formed from diazobenzene sulphonic
acid and a-naphthol. If /3-naphthol, in alkaline solution, be used, then the pro-
duct will be ^-napkthol-azo-benzene sulpkonic acid, Cj(|Hg(OH).N2.C5Hj.S03H.
Its sodium salt is the P-napkthol orange (Orange II) of trade.

Various Ponceaus and Bordeaus (R, RR, G,GG, etc.) are obtained by means
of /?-naphthol disulphonic acids from diazo-xylidines and diazocumidines (p.
624). Biebrich Scarlets are obtained from the sulphonic acids of amido-azo-
benzene, CgHj.Nj.CgH^.NHj (the chlorides) with ;8-naphthol. They are tetrazo-
compounds {Berickte, 13, 1838). Crocein Scarlet {Berickte, 15, 1352), from
/3-naphthol sulphonic acid, is also of importance.

652 ORGANIC CHEMISTRY.

Fast Brown is a disazo- or tetrazo-compound. It is the disulphonic acid ot
a-naphthol disazobenzene, which may be prepared by the union of two molecules
of diazo-sulphanilic acid with a-naphthol \Berichte, 21, 3241).

Diazonaphthalene sulphonic acid and yS-naphthol combine and produce ^-
Naphtholazonaphthalene sulphonic acid, CioHg(OH).Nj.C,oHg.S03H. The sodium
salt of the latter is fast red or rocellin, which serves as a substitute for archil or
cochineal.

Thetetrazo-dyes, derived from benzidine and toUdine, are especially important,
as they color unmordanted cotton, and the product is not affected by soap. Congo
red, chrysamine, azo-blue, benz-azurine, Congo yellow, etc., are of this class (see
Benzidine).

Mixed Azo compounds.

In this class the azo-group is linked to a benzene nucleus, and to a paraffin
residue.

Azo-phenyl-methyl, CgHj.Nj.CHj, Benzene azomethane, is made by oxi-
dizing a-methylphenyl hydrazine (p. 657) with mercuric oxide. It is a yellow,
volatile oil, with a peculiar odor. It boils at 1 50°- Sodium amalgam reduces it
to a- methylphenyl hydrazine [Berichte, 18, 1742). Azo-phenyl-ethyl, CgHj.
Nj.CjHj, has been similarly prepared from a-ethyl-phenyl-hydrazine. It closely
resembles the methyl compound. It melts about 1 80°.

Azo-phenyl-nitroethyl, CgH5.N2.CH(N02).CH3, Benzehe-azo-nitro-
ethane, is obtained by the action of diazobenzene nitrate, CgHj.Nj.NOj, upon
sodium nitroethane. It crystallizes in orange colored laminae, melting at 137°.
It behaves like an acid, dissolving in alkalies with a blood-red color, and forming
basic salts, containing two equivalents of the bases {Berichte, 8, 1076; 9, 384).

Compounds, regarded as mixed azo-derivatives, have been similarly prepared
by the interaction of benzene-diazo-salts and various fatty bodies. However, a
transposition occurs when they are produced and hydrazones result (p. 656) (see
Japp, Annalen, 247, 190 ; Berichte, 21, Ref. 725 ; V. Meyer, Berichte, 21, ll).

Thus, when benzene diazo-salts act upon malonic ester, the product is not the
expected benzene-azo-malonic acid, but its isomeride, phenyl hydrazon-mesoxalic
acid : —

CsH5.N2.CH(C02H)j becomes C^li^.T<in.lfi:C{CO^Yi)^,
Bcnzene-azo-malonic Acid. Phenyl-hydrazon-mesoxalic Acid.

as it is also formed by the action of phenyl-hydrazine upon mesoxalic acid fp. 434).
Similarly, diazo-benzene chloride and acetoacetic ester do not produce benzene-
azo-acetic ester, but the hydrazone of aceto-glyoxylic ester ( Berichte, 20, 2121) :

CsH5.N:N.Ch/^°-^^3 becomes C^Hj.NH.NiC/^^-^^^

Benzene-diazo chloride acts upon benzoyl-acetic ester in the same manner. Ben-
zene-azo-acetone, CjH5.N2.CH2.CO.CHj {Berichte, 17, 2415), resulting from
the decomposition of the ester that is formed, is the hydrazone of pyro-racemic
aldehyde, CjH^.NH.NiCH.CO.CHj (p. 323).

Benzene diazo-salts displace the acetyl group of mono-alkylic aceto-acetic esters.
In doing this, they do not form the benzene-azo-fatty acids, but the hydrazones ai
a-ketonic acids {Berichte, 20, 3398) : —

CjH5.N2.CH/^^3j^ becomes CeH5.NH.N:C/^^Sj^.

Benzene-azo-propionic Acid. Hydrazon-pyro-racemic Acid.

HYDRAZINE COMPOUNDS. 653

When the benzene-diazo-salts act upon the free alkyl-aceto-acetic esters, carbon
dioxide is evolved, and hydrazones of o-diketones result [Berichte, 21, 549) : —

CeH3.N,Cl + CH(CH3)/^0^^^» = CeH,.NH.N:C/^^'(,jj^ + HCl.

Diacetyl-hydrazone.

However, in other cases, the action of the benzene-diazo-salts proceeds in the
normal way. Rearrangements do not occur, and mixed azo-QomT^\m.ds, are produced
(Berichte, 21, 1697). Acetaldehyde reacts in this manner (p. 323) .■ —

C,H,.N,C1 +CH,/^0.CH3 ^ CeH,.N,.C9/^g-^^3;

Benzene-azo-acetaldehyde.

also, aceto-acetone, CHj.CO.CHj.CO.CHj, and dibenzoyl-methane. The mixed
azo-compounds, obtained from them, dissolve unaltered in alkalies, and being
;8-carbonyl derivatives, unite with phenyl-hydrazine and form hydrazones, which
lose water and become pyrazole-derivatives (p. 327). Benzene-azo-cyanacetic
ester, C5H5.N2.CH(CN).C02R, is thus formed from cyanacetic ester and benzene-
diazo-chloride (Berichte, 21, Ref. 354).

HYDRAZINE COMPOUNDS.

The hydrazines studied by E. Fischer in 1877 {Annalen, 190, 67)
are intimately related to the diazo-compounds : —

CjHs.NrN.O.NO^. CeH5.NH.NHj.HNO3.

Diazobenzene-nitrate. Hydrazine Nitrate.

They are derivatives of diamide or hydrazine, H2N.NH2, which
has only recently been obtained in a free condition (^Berichte, 20,
1632). (p. 166). They are formed : —

I. By the action of alkaline sulphites upon the diazo-derivatives.
On allowing neutral potassium sulphite to act in the cold upon
diazobenzene nitrate or hydrochloride, the yellow colored potas-
sium salt of diazobenzene-sulphonic acid will be produced at first
(p. 636) :-

C5H3.N2.NO3 + SO3K2 = qH5.N2.SO3K + NO3K;

but should the primary potassium sulphite act at 20-30", the diazo-
sulphonic acid will be further reduced, and colorless potassium ben-
zene hydrazine-sulphonate will be formed immediately : —

C6H5.N2.SO3K 4- H2 = CjH3.N2.H2.SO3K.

The yellow diazosulphonate can be reduced to the hydrazine
compound by sulphurous acid, or better, with zinc dust and acetic
acid.

When the sulphonate is heated with hydrochloric acid hydrazine
hydrochloride is produced : —

CeH3.N2.H2.SO3K -f- HCl + H2O = CeH3.N2H3.HCl + SO^KH ;
the alkalies separate the free hydrazine, CsHj.NjHa.

654 ORGANIC CHEMISTRY.

Preparation. — In making phenyl hydrazine (benzene hydrazine) dissolve 20
parts of aniline in 50 parts of hydrochloric acid (sp. gr. i . 1 9) and 80 parts water,
and then add the equivalent amount of sodium or potassium nitrite (dissolved in 2
parts water). The solution contains diazobenzene chloride, CjHj.NjCl, and is
gradually added to a cold solution of sodium sulphite (2 molecules); sodium
phenyl hydrazine sulphonate then separates, but is mixed vpith the yellow diazo-
sulphonate, which is completely reduced by digestion with zinc dust (with addi-
tion of acetic acid). The filtered, colorless solution of the hydrazine-sulphonate
is boiled with concentrated hydrochloric acid (^ volume), and the hydrazine
separated by means of caustic soda (Annalen, 190, 78). A modified method for
the preparation of phenylhydrazine will be found in the Berichte, 20, 2463.

The sulphaeides, e. g.yC^^.^^.^m.SiO ^.C ^a ^, phenyl-bemene siilphazide, are
prepared by the action of free sulphurous acid upon the acid solution of diazoben-
zene salts, or by the interaction of nitrous acid, and an alcoholic aniline base super-
saturated with SOj (Berichte, 20, 1238). These are to be regarded as benzene sul-
phinic acid derivatives (p. 662) of the hydrazines. They are also formed when
benzene sulphonic acid chloride, CgHg.SOjCl, and benzene sulphinic acid, CjHj.
SOjH, act upon phenyl hydrazine [Berichte, 18, 893). Warm alkalies resolve
the sulphazides into benzene and benzene-sulphinic acid : CgH5.NH.NH.SO2.Cj
H5 yields CgHg + Nj -j-CjHj.SOjH. Mercuric oxide oxidizes phenyl-benzene-
sulphazide to benzene-sulphin -diazobenzene, CgHj.Nj.SOj.CjHj, and conversely
can be obtained from the latter (from diazobenzene nitrate and sodium benzene
sulphinide) by reduction with zinc dust.

2. By the action of stannous chloride and hydrochloric acid upon
the diazo-chlorides (V. Meyer, Berichte, 16, 2976) : —

CjH^.NjCl -f 2SnCl2 + 4HCI = CjH5.N2H3.HCl + aSnCl^.

This procedure affords results which are especially good, if the
hydrazine chloride {e. g., naphthyl hydrazines) dissolves with diffi-
culty {Berichte, 17, 572).

3. By the reduction of diazo-amido-compounds in alcoholic solution with zinc
dust and acetic acid, when they decompose into anilines and hydrazines: —

CH5.N2.NH.CeH5 + 2H2 = CeH^.N^H, + NH2.C5H5.
Diazo-amldo-benzene. Phenyl-hydrazine. Aniline.

4. By the reduction of the nitroso-amines (pp. 164 and 598) with zinc dust
and acetic acid : —

c:h:>N-NO + 2H2 = ^«g=>N.NH2 + H2O.

Phenyl-ethyl Nitrosamine. Phenyl-ethyl Hydrazine.

The benzene hydrazines are very similar to those of the marsh-
gas series, but are less basic and in consequence are only capable of
uniting with one equivalent of acids to form salts. Generally they
are easily fusible and boil with but slight decomposition.

When boiled with copper sulphate or ferric chloride {Berichte,
18, 786) the phenylhydrazines throw off nitrogen and become
benzenes — this reaction will also serve for the replacement of the

■PHENLYHYDRAZINE. 655

diazo-group by hydrogen (p. 633). The liberated nitrogen also
answers for the quantitative estimation of the hydrazines {Berichte,
18, 3177)-

The hydrogen of the imide group in the phenylhydrazines can
be replaced by sodium, the nitroso groups by alkyls and acid radi-
cals ; alkyl- and acid derivatives of the NHj-group (see below) are
also known.

Phenylhydrazones (p. 656) are produced by the union of the
phenylhydrazines with aldehydes, ketones, aldehydic and ketonic
acids.

Although the hydrazines are very stable in the presence of
reducing agents, they are readily oxidized and destroyed. They,
therefore, reduce salts of the heavy metals and precipitate cuprous
oxide from Fehling's solution ; in this case the primary hydrazines
and the a-alkyl derivatives react even in the cold.

The phenyl hydrazines may be readily reconverted into diazo-
compounds by moderated oxidation ; this is effected by the action
of mercuric oxide upon their sulphonates : —

CjH5.NH.NH2.HX -1- 2O = CgHj.NiN.X + 2HjO.

Phenylhydrazine, CeHj.NH.NHj, is obtained from benzene
diazochloride by reduction with sodium sulphite or stannous chlor-
ide (p. 653). It is a colorless, peculiar-smelling oil, solidifying,
when cooled, to plate-like crystals, melting at 23°; sp. gr. 1.091 at
21°. It boils at 241-242° with slight decomposition {Annalen, 236,
198). It dissolves with great difficulty in cold water, but readily in
alcohol and ether. It assumes a light brown color on exposure to
the air. It serves as an important reagent for the detection of
aldehydes and ketones (see above) and has been applied in a very
great number of syntheses (that of antipyrine).

Nitrous acid converts it into diazobenzene imide. When sodium nitrite acts
upon HCl-phenylhydrazine in the cold nitroso-pfanylhydrazine, C5H5,N(NO).
NH2, separates as a yellow-brown oil, solidifying to yellow laminse. Dilute alka-
lies decompose this compound into water and diazo-benzene-imide.

Metallic sodium dissolves in phenylhydrazine, forming the sodium derivative,
CsH5.NNa.NH2. This is a yellowish red, amorphous mass.

Alkyls and acid residues can replace the sodium, thus producing ;3-phenyl-
hydrazine derivatives (p. 657) {^Berichte, 19, 2448; 22, Ref. 604).

Substituted derivatives may be obtained from the substituted anilines {Berichte,
22, 14). /-Bromphenylhydrazine, CjH^Br.NjHg, melts at 106° and forms
hydrazines. p-Nitrophenylhydrazine, C5H,(NOj).N2H3(i, 2), from o-nitrani-
line, forms brilliant red needles, nuelting at 90°. Sodium amalgam reduces its

,N— CH
formyl compound to Bmzotriazine, CMa I {Berichte, 22, 2806).

\n-n

The sulphonates are formed by the reduction of diazobenzene-sulphonic acids
with sodium sulphite or stannous chloride (Berichte, 22, Ref. 216), and also by

656 ORGANIC CHEMISTRY.

the direct action of concentrated sulphuric acid upon the phenylhydrazines
{BericAte, 18, 3172).

/-Hydrazine-benzenesulphonic Acid, C6H4.(NH.NH2)S03H, is not read-
ily soluble in water. It is used in the preparation of tartrazine (p. 492).

The digestion of phenylhydrazin j^ with KjSjO,, or the addition of diazobenzene
nitrate to a solution of potassium bisulphite, gives rise to the potassium salt of
Benzene-hydrazine Sulphonic Acid, CsH^NH.NH.SOjH. The salt crystal,
lizes in scales, dissolving in water with difficulty.

Phenylhydrazones {JBerichte, 21,984).

Phenylhydrazones, or hydrazones, are produced by the action
of phenylhydrazine upon carbonyl compounds, when the amido-
group reacts with the CO-group : —

CjH5.NH.NH2 + CHO.CH3 = CgHs.NH.NiCH.CHj + H^O.

Aldehyde Hydrazone.

This is confirmed by the analogous deportment of the ^-alkyl phenylhydrazines
(p. 657) :—

CjHj.NCCHjj.NH^ + CO(CH3)2 = C8H5.N(CH3).N:C(CH3), + H,0;

Acetone-methyl-phenyl Hydrazone,

as well as by the formation of indol derivatives from the hydrazones, and by the
■behavior of benzal-jhenyl hydrazone {^Berichte, 20, 2487).

The reaction proceeds in an aqueous or alcoholic solution (Berichte, 17, 573).

A solution of I part HCl-phenylhydrazine with lyi, parts sodium acetate in 8-
10 parts water, is well adapted as a reagent for the compounds soluble in water.

The aldoximes and acetoximes, or isonitroso-compounds, react in a similar
manner. The phenyl-hydrazine replaces the isonitroso group {^Berichte, 19,
1205) :—

C5H5.NH.NH, -f HO.N;C(CH3), = CsHj.NH.NiqCHj)^ -f NH,.OH.

A peculiar formation of hydrazones is that in which benzene diazo-salts act upon
different CH- and CH2-compounds (p. 652). The a-diketone derivatives yield
mono- and di-hydrazones ; the latter are called osazones (p. 326). The glucoses
(aldehyde- and ketone-alcohols) deport themselves similarly, as they yield both
hydrazones and osazones (p. 501). The /3-keto-compounds first form hydrazones
with one molecule of phenylhydrazine, but by the exit of water, they condense to
pyrazole- z.n.&. pyrazolon-AenvzAsti (p. 339).

The hydrazones are usually crystalline compounds, insoluble in water. They
are yellow or brown in color. They almost invariably decompose upon fusion,
hence their melting points are only correct when they are heated rapidly. If di-
gested with mineral acids they absorb water, more or less readily, and revert to
their components. Pyroracemic acid brings about the decomposition more easily
{Berichte, 22, Ref. 674).

Some hydrazones are decomposed by reduction (sodium amalgam, tin and hydro-
chloric acid, or sodium and absolute alcohol), when they yield anilines and amido
acids (see amido- valeric acid, p. 372) {Berichte, 20, 3399).

Nearly all phenyl hydrazones are condensed, upon heating them with concen-
trated mineral acids, or zinc chloride, to indol derivatives. Ammonia is expelled.

The hydrazones have, in most cases, been mentioned in connection with the
corresponding carbonyl compounds. Those of the aldehydes and ketones of the
fat series are generally yellow oils (Annalen, 236, 126, 137).

ALKYLIZED HYDRAZINES. 657

Ethidene Phenyl-hydrazone, CHjCHiN^H.CsHj (isomeric with benzene-
azo-ethane), becomes crystalline in the cold. It boils at 250°. Propidene Hy-
drazone, CjHj.CHiNjH.CgHj, boils undecomposed under diminished pressure.

Acetone Hydrazone, (CH3)2.C:N2H.C5H5, can also be distilled under dimin-
ished pressure.

Pyroracemaldehydrazone, CjH5.NH.NfbH.CO.CH3 (p. 323), formerly con-
sidered as Benzene-azo-acetone, CgHj.N^.CHj.CO.CH, (p. 652), is produced
by the ketone decomposition of hydrazone-acetoglyoxylic ester, induced upon di-
gesting it with alkalies {Berichte, 17, 2415). It crystallizes in yellowish-brown
prisms, melting at 149°. Sodium ethylate and alkyl iodides, or chloracetic ester,
displace the hydrogen of its imide group (Berichte, 2g, 3398). Phenyl hydrazine
converts it into the 0M20«^ of pyroracemic aldehyde, CH3.C(NjH.C5H5).CH(N2H.
CgHj) (p. 323), which can also be obtained from acetol and isonitroso- acetone
{Berichte, 20, 3399). It does not react with phenyl cyanate {Berichte, 23, 496).

Pyroracemic-acid Hydrazone, CH3.C(NjH.C5H5).C02H (p. 332), is identi-
cal with benzene-azo-propionic acid (p. 652). Sodium amalgam converts it into

Hydrazido-propionic Acid, CjHj.NH.NH.Ch/^q s^

Glyoxylic-acid Hydrazone, CeH5.NH.N;CH.cd2H, by reduction yields
Phenylhydrazido-acetic Acid, CgHj.NH.NH^.CHj.CO^H, which can also be
prepared by reducing nitroso-phenylglycin, C8H5.N(NO).CH2.C02H.

Alkylized Hydrazines : —

CsH5.NH.NH.CH, and CeH5.N(CH3);NH2.
fli-Methyl-phenyl-hydrazine. /3-Methyl-phenyl-hydrazine.

The o-derivatives are termed jj/TOOT^/nVa/, the /3-compounds«Kij/»z««^/nVa/alkyl-
phenylhydrazines. Both isomerides are produced by the action of alkyl bromides
upon phenylhydrazine {Annalen, 199,325; Berichte, 17,2844). The ;8-class are
also obtained by the action of ethyl bromide upon sodium phenylhydrazine
{Berichte^ ig, 2420, 22, Ref. 664), and by the reduction of the nitrosamines
(p. 654). The a-derivatives reduce FehUng's solution even at the ordinary tem-
perature (like the primary hydrazines), but the /3-class only act in this way after
warming. By oxidation (chiefly by. means of mercuric oxide) the a-deriva-
tives pass into azo-compounds, like azophenylmethyl, C5H5.N.N.CH3 (p. 652),
which by reduction revert to the original bodies. The /3-derivatives, on the con-
trary, liberate it, and become secondary anilines, or they form the tetrazones (see
below). Nitrous acid causes the /3-compounds to split off the NH^ group and yield
nitrosamines, e.g., C5H5.N(NO).CH3.

a-Methylhydrazine, C3H5.NH.NH(CH)3, results upon distilling methyl diben-
zoylphenyl hydrazine (p. 658) with potash. It is rather unstable. It is easily
oxidized by mercuric oxide to azophenylethyl {Berichte, 18, 741).

a-Ethyl-phenyl hydrazine, CgH5.NH.NH(C2H5), is produced when azo-
phenyl-ethyl is reduced with sodium amalgam {Annalen, igg, 330). It is a
colorless oil. Mercuric oxide or nitrous acid will re^oxidize it to azophenyl-methyl.

P-Methyl-phenyl hydrazine, CgH5N(CH3).NH2, and ^-Ethyl-phenyl hydrazine
are obtained by the reduction of nitroso-methyl and nitroso-ethyl aniline by means
of zinc dust (p. 654) ; the first boils about 227° {Annalen, 236, 1 98), the second at
232° {Berichte, ig, 2450). The ethyl compound unites with ethyl iodide to the
bromide, CgH5'.N(CjH5)2Br.NHj, which by reduction yields diethyl-aniline
{Berichte, 17, 2844).

a-Allyl-phenyl hydrazine, C3H5.NH.NH.C3H5, boils at 177° under no mm.
pressure {Berichte, 22, 2233).

55

658 ORGANIC CHEMISTRY.

P-Etkylme-phenyl hydrazine, C2H^(N(NHj).C5H5)2, from sodium phenyl hydra-
zine and ethylene bromide, melts at 90° {Berichte, 22, Ref. 810).

a-Diphenyl-hydrazine, (C8H5)2.N.NH2, isomeric with benzene hydrazine from
nitrosodiphenyl-amine, crystalUzes in plates, melting at 34°, and boiling at 220°
under 50 mm. pressure, or dissolves in sulphuric acid with a dark blue color.
{Berichte, 22, Ref. 582). It forms rather insoluble diphenyl-hydrazones when
digested with the glucoses (p. 501).

Tetrazones. »

These are produced from the ^-alkyl-phenylhydrazines by oxidation with mer-
curic oxide in alcoholic or ethereal solution, or by means of a dilute ferric chloride
solution : —

2CsH5.N(CH3).NH2 + 20 = CeH5.N(CHs).N:N.N(CH3).C,H5 + 2H2O.

They are solids which undergo decomposition when fused or boiled with dilute
acids.

Diniethyl-diphenyl Tetrazone, C,H5.N(CH3)N.^.N(CH3).C5H5, crystallizes
in leaflets, melting at 133°. The diethyl derivative melts at 108°. The teiraphenyl
compound, from a-diphenylhydrazine, melts at 123°, and is colored blue by con-
centrated acids.

Acid Derivatives of Phenylhydrazine, or Hydrazides : —

CsH5.NH.NH.CO.CH3 and CeH5.N(CO.CH3).NHj.
a-Acetyl Hydrazine. )8-Acetyl Hydrazine.

The a-compounds are obtained by the action of free acids, acid chlorides, acid
anhydrides and acid esters upon phenylhydrazine.

Free acids (especially the polyhydric oxy-acids), as well as the lactones, react
directly upon digesting them in an acetic-acid solution [Berichte, 22, 2728). The
hydrazides of the.monobasic acids are mostly readily soluble in hot water (p. 489),
but the dihydrazides of the polybasic acids dissolve with difficulty. Boiling alka-
lies and baryta water decompose them all with the separation of phenylhydrazine.
The hydrazides are distinguished from the hydrazones by the red-violet color that
they yield with concentrated sulphuric acid and a little ferric chloride (Reaction
of Biilow, Annalen, 236, 195 ; Berichte, 23, 3385).

o-Formyl-hydrazine, C5H5.NH.NH.CHO, melts at 140°; o-acetyl-hydra-
zine, at 128°. a-Benzoyl-hydrazine melts at 168°; mercuric oxide oxidizes
it to benzoyl-diazobenzene, CjHj.NiN.CO.CgH, {Berichte, ig, 1203). The
structure of a-benzoyl hydrazine is proven by the methyl derivative of benzoyl- and
dibenzoyl-hydrazine {^Berichte, 18, 1739). The ^-phenyl hydrazides are formed
when acid chlorides or anhydrides act upon sodium phenylhydrazine {Berichte,
22, Ref. 66s). /3-Benzoyl-hydrazine, C5H5.N(CO.C5H5).NH2, melts at 70°.

Phosgene converts the ffi-phenyl hydrazides into carbizine derivatives {Berichte,

N=CH
21,2456). These, probably, contain the " ring-shaped " ^/azo/if <r.4az«, I ^-O

N=CH
{Berichte, 23, 2821). Carbon disulphide produces thio-carbizines, derivatives of
thio-biazole, CjHjNjS.

SO 2 converts phenylhydrazine into hydrazides of sulphurous acid, CgHj.N^Hj.
SO2 and (CjH5.N2H3)jS02 {Berichte, 23, 475).

SULPHO-COMPOUNDS. 659

Homologous Phenylhydrazines.

»-Tolyl-hydrazine, CgH4(CH3).NH.NH2,from orthotoluidine, crystallizes in
shining leaflets melting at 59°, When digested with sulphuric acid, it becomes a
sulphoacid, C8Hj(CH3)(N2H3).S03H ; the sulpho-group occupies the para-posi-
tion with reference to the hydrazine-group {Berichle, 18, 3175 ; ig, Ref. 301).

j!i-Tolyl-hydrazine, CgHj(CH3).NH.NH2, from para-toluidine, melts at 61°,
and distils about 242°. When digested with sulphuric acid, it changes to a basic
compound (^i?r2V,4/^, 19, Ref. 837).

SULPHO-COMPOUNDS.

The following are representatives of this class of derivatives : —

Benzene Sulphonic Acid, CjHj.SOjH.
" Sulphinic " CgHj.SOjH.

Sulphone, (CeHjj^SO^.

Disulphoxide, (CuHsJ^SjOj.
" Sulphoxide, (C5H5)2SO.

The sulphonic acids of the benzene hydrocarbons (as well as of
all other benzene derivatives) are very easily obtained by mixing
(or digesting) the latter with concentrate'd or fuming sulphuric
acid. The fatty acids yield like products with more difficulty (pp.
152 and 261) : —

CeHe -f SO^H^ = CeH^.SOjH + H^O,
C^H, + 2S0^H2 = CeH^(SO,H), -f 2H,0.

Chlorsulphonic acid, Cl.SOjOH {Berichte, 18, 2172), acts similarly to sul-
phuric acid. With it we can obtain the trisulpho-acids (Berichte, 15, 307). Fur-
ther, some sulphonic acids can be obtained from the diazo amido-derivatives by
means of sulphurous acid (p. 635 and Berichte, 10, 1715).

The chloranhydrides of the sulphonic acids, e. g., CeHj.SOuCl,
are produced by letting PCI5 act on the acids, or POCI3 upon the
salts. Ammonia converts these into sulphamides, CjHs SOj.NHj,
and zinc and hydrochloric acid will reduce them to sulphydrates
(thio-phenols) (p. 152) : —

CjHj.SOjCl + 3H, = CeH^.SH + 2H,0 + HCI.

The sulphinic acids of benzene, with the structure CeHj.SO.OH or

C H \

■R / ^^2 a-fe perfectly analogous to those of the fatty series

(p. 154). They are best prepared by the action of zinc dust upon the
ethereal solutions of the sulphonic chlorides (^Berichte, 13, 1273).
They also result in the action of SO2 upon benzene in the presence
of AICI3 {Berichte, 20, 195) :— CeHe + SOj= QHs SO^H.

66o ORGANIC CHEMISTRY.

The real esters of these acids, CgHj.SO.O.CjHj, are formed by the action of
cWorcarbonic esters upon sulphinates (p. 154), and by the etherification of the free
sulphinic acids with alcohol and HCl (Berichte, 18, 2506; ig, 1224). The esters
are not very stable ; alkalies saponify them, yielding sulphinates and alcohol, etc.
The sulphones, X\itvc isomerides, e.g., {C^li^^SiO.^, diphenyl-sulphone (p. 142),
are obtained by the action of SO3 (or chlorsulphonic acid, CISO3H) upon benzenes
(together with sulphonic acids): 2CgHj + SO3 = (CgH5)jSOj + HjO. ; by
the distillation of sulphonic acids (together with benzenes), and by the oxidation
of the phenyl sulphides, e.g., (0^115)28, with nitric acid.

The benzene sulphones are formed synthetically on heating sulphonic acid with
benzene and P^OsiCjHj.SOjH + C^ll^ = CeH5.SO2.C5H5 + H^O; further,
by the action of zinc dust or aluminium chloride upon a mixture of the sulphonic
chlorides and benzenes; mixed sulphones are also produced in this manner: —

C3H5.SO2CI + C^Hj.CHg = c^H,(CH3)/^°2 + H^'-

The same phenyl tolyl-sulphone results from benzene sulphonic acid and toluene
as from toluene-sulphonic acid and benzene, which would prove that both groups
are in union with sulphur and that the latter is sexivalent [Berichte, 11, 2181).
Mixed sulphones, containing alkyls, are prepared from the sodium sulphinates
by the action of the alkylogens (p. 142) : —

CjHj.SOjNa + CjH5Br = c^h'/SO^ + NaBr.

. Phcnyl-ethyl-

sulphone.

The benzene-thiosulphonic acids are formed when alkaline sulphides act upon
the chlorides of the sulphonic acids : —

CjHj.SOjCl + KjS = CjH5.SOj.SK + KCl.
Potassium Benzene-
thio-sulphonate.

And by acting on these salts with alkylogens, esters of the thio-sulphonic acids
(the disulphoxides) will be produced {^Berichte, 20, 2079) '- —

CeH5.SO2.SK + C2H5I = C,H5.S02.S.C2H5 + KI.

These are identical with the so-called alkyl-disulphoxides (p. 154).

Phenyl esters, e.g., C5H5.S02.S.CgH5, are obtained by oxidizing the thio-
phenols with nitric acid and by heating the sulphinic acids with water. (Berichte,

18, 2500). Alkalies and alkaline sulphides saponify them (p. 154 and Berichte,

19, 3130-

The benzene sulphoxides are produced by the action of SO^ or SOjClj upon
benzenes in the presence of AICI3 (Berichte, 20, 191) ; —

2C.Hj + SOCI2 = (CjH5)2SO + 2HCI.

The benzene sulphonic acids are perfectly analogous to those of
the fatty series. They are very stable and are not decomposed on
boiling with alkalies. They yield phenols when fused with
alkalies : —

C3H5.SO3K + KHO = C5H5.OH + SO3KJ.

BENZENE-SULPHONIC ACID. 66l

When distilled with potassium cyanide (or dry yellow prussiate of
potash) nitriles result : —

C,H,.S03K + CNK = CeH,.CN + SO3K,.

Amido-compounds are produced when sodium amide acts upon
benzene sulphonates {Berichte, 19, 903) : —

CsHj.SOaNa + NH^Na = CjHs.NH^ + SOaNa^.

Hydrocarbons (together with phenyl sulphones) are formed when
the free acids are subjected to distillation : —

CeH,,.S03H = C^H, + SO3.

This rupture is more easily accomplished by heating the acids with concentrated
HCl to 150°, or by distilling the ammonium salt of the sulphonic acid, or a
mixture of the lead salt with ammonium chloride (Berickie, 16, 1468). The
decomposition results with least diflficulty by conducting steam into the dry sulpho-
acid, or its solution in concentrated sulphuric acid; superheated steam is most
effective (Berichte, ig, 92).

The sulphonic acids of the substituted hydrocarbons are obtained either by the
action of sulphuric acid on the substituted hydrocarbons, or by the substitution of
the sulphonic acids. In nitration the sulpho-group is often replaced by the nitro-
group, just as on heating with PCI5 it is sometimes substituted by chlorine : —

CjHjCl.SOaCl + PCI5 = CjH^Cla + PCI3O + SOCl^.

Most of the substituted benzene sulphonic acids have their sulpho-group replaced
by hydrogen if they are heated to 150-200° with concentrated hydrochloric
acid : —

CjH.Br.SOgH + H,0 = C^H^Br + SO,H,.

Nitro-benzenes and amido-benzenes result in like manner from the nitro-benzene-
and amido-benzene-sulphonic acids {Berichte, 10, 317). Chlorine and bromine
occasionally effect a like replacement of the sulpho-group [Berichte, 16, 617).
The brominated benzene-sulphonic acids can form sulpho- anhydrides, e. g.,

^e'^sP'^z-SOzXo. They result from the action of pyrosulphuric acid, (802)20

^6*^a^^2-^02/

(OH)2, upon brombenzenes [Berichte, 16, 653).

The sulphinic acids are not very stable, and when heated or allowed to stand
some time over sulphuric acid they split up into sulphonic acids and disulphoxides
(Berichte, 18, 2500).

The air and oxidizing agents (especially BaOj) convert them into sulphonic
acids. Their salts unite with sulphur, forming thio-sulphonates. When fused,
they decompose into benzenes and alkaline sulphites : —

CgHj.SOjK + KOH = CjHo + SO3K2.

Benzene-sulphonic Acid, CsHj.SOsH. For its preparation
equal parts of benzene and ordinary sulphuric acid are boiled for
some time; or benzene is shaken with fuming sulphuric acid.
Afterwards dilute with water and saturate with barium or lead car-

662 ORGANIC CHEMISTRY.

%

bonate. The free sulphonic acid is separated from its salts by
means of sulphuric acid or hydrogen sulphide.

Benzene sulphonic acid crystallizes in small plates, CbHj SO3H
4- i^HjO, which are readily soluble in alcohol and water, and
deliquesce in the air. In its dry distillation the acid yields ben-
'zene and phenylsulphone (in slight quantity), and when fused with
caustic potash phenol is produced.

The barium salt, (CjHj.SOjjjBa + H^O, forms^pearly leaflets, and is sparingly
soluble in alcohol. The nine salt, (CeH5.S03)2Zn -|- 6H2O, crystallizes in six-
sided plates.

Benzene-aulpho-chloride, CjHj.SO^Cl, is an oil, insoluble in water, but
dissolved by alcohol and ether. Its specific gravity at 23° is 1.378. It is crystal-
line belovir 0°, and boils at 247° with decomposition. It slovply reverts to the
acid upon boiling with water. It may be obtained by gently digesting CgH 5 .SOjNa
with PCI5 and treating the product with water. If the chloride be digested with
ammonia or ammonium carbonate we obtain —

Benzenesulphamide, CjHj.SO^.NHj, which crystallizes from alcohol in
pearly lamina. It melts at 149° and suMimes. From the alcoholic solution silver
nitrate precipitates CjHj.SOj.NHAg. The amide hydrogen can also be re-
placed by acid or alcohol radicals.

Benzene Sulphinic Acid, CgHj.SOjH (its zinc salt), is obtained by the
action of zinc dust upon benzene sulphochloride. It crystallizes from hot water in '
large, brilliant prisms, and dissolves readily in alcohol and ether. It melts at 69°,
and decomposes at 100°. In the air it oxidizes readily to benzene sulphonic acid.
The silver salt, CgHj.SOjAg, is sparingly soluble in water.

Phenyl Ethyl Sulphone, CjHj.SO^.C^Hj, is formed in the oxidation of

P FT \
phenyl-ethyl-sulphide, p^u' /&, with potassium permanganate, and from sodium

benzene sulphinate with ethyl bromide (p. 660). It melts at 42° and boils above
300°. Isomeric benzene-sulphinic ester, CgHg..SO.O.C2H5, is only known in
mixtures (p. 659).

Di-phenylsulphone, (€5115)2802, Benzene Sulphone, Sulphobenzide, is formed
by the distillation of benzene sulphonic acid, and by the oxidation of phenyl sul-
phide, (CgHjjjS; further, from benzene sulphonic chloride, CjHj.SOjCl, and
mercury diphenyl. It is also obtained by the action of fuming sulphuric acid, or
SO3 upon benzene. It dissolves with great difficulty in water and crystallizes from
alcohol in plates. It melts at 128-129°, and distils without decomposition. It is
converted into benzene-sulphonic acid when digested with concentrated sulphuric
acid : —

(CeH5)2S02 + SO.Hj = 2C,H,.S03H.

When heated with PCI5, or in a current of chlorine gas, it is decomposed according
to the equation : —

(C,H5),S02 -f CI, = CeH^Cl -f CeH^.SO^Cl.

CgHjCl and its addition products are also formed when chlorine acts upon it in
sunlight.

Benzene disulphoxide, (05115)28202 (p. 659), is produced along with benzene
sulphonic acid on heating benzene sulphinic acid with water to 130°- It crystal-
lizes in shining needles, and melts at 130°. It is insoluble in water but is readily
dissolved by alcohol and ether.

CHLORBENZENE-SULPHONIC ACIDS. 663

Ethylene Diphenyl-disulphone, | (p. 307), is obtained from

CH,.S0,.C6H,,
ethylene bromide and sodium benzene sulpbinate. Wlien heated with alkalies, it
breaks down into benzene sulphinic acid wx& phenylsulphone-ethyl alcohol, CgHj.
SOj.CHj.CHj.OH; chromic acid oxidizes this to phenylsulphone-acetic acid,
CjHj.SOg.CHj.COOH {Berichte, 18, 155). The latter compound and its esters
are obtained from sodium phenylsulphinate by the action of chloracetic acid. The
hydrogen of the CHj-group in the ester is, indeed, replaceable by sodium, but not
by alkyls {^Berichte, 22, 1447 ; 23, 1647).

See Berichte, 23, 752, 1409, for analogous di- and tri-sulphones, as well as their
decompositions, etc.

a- and ^-Phenyl-sulpho-propionic Acids, CgH5.S02.CH(CH3).C02H,
have been prepared in a similar manner [Berichte, 21, 89).

Benzene-disulphonic Acids, CgH^(' co'h- On heating benzene with fuming

sulphuric acid to 200° C, we get meta- and /a?-rt-benzene disulphonic acids, with
the former in predominating quantity, but by prolonged heating it passes into the
/arfl-variety {^Berichte, 9, SS°)' They can be separated by means of their potas-
sium salts. A?f/a-disulphonic acid (i, 3) is produced by heating parabrombenzene-
sulphonic acid with sulphuric acid to 220° and displacing the bromine with sodium
amalgam, or from disulphanilic acid (p. 666) by means of the diazo-compound.

Orthobenzene disulphonic acid ( i , 2) is formed from metaamido benzene sul-
phonic acid by further introduction of the sulpho-group, and replacement of NHj.
The melting points of the sulphochlorides and sulphamides of the three isomeric
disulphonic acids are : — -

Ortho. Meta. Para.

CeH,(SO,Cl), 105° 63° 132°

CeH.lSO^NH^), 233° 229° 288°.

The corresponding dicyanides^C^^l^'),^ (see nitriles), are obtained by dis-
tillation with potassium cyanide or potassium ferrocyanide. When fused with
potassium hydroxide, both meta and para acids yield resorcinol (metadioxyben-
zene); at lower temperatures metaphenol-sulphonic acid, 0^114(011) SO3H,
results at first from both acids.

Benzene-trisulphonic Acid, €5113(50311)3 (1,3, S), is easily made by heat-
ing potassium 7«-benzene disulphonate with common sulphuric acid (Berichte, 21,
Ref. 49). The free acid (from the lead salt) crystallizes in long needles with
3H20;its chloride melts at 184°; its amide at 306°. Fused with caustic potash
it yields phloroglucin, CgH3(OH)3, and upon heating with potassium cyanide it
forms the nitrile, which upon saponification becomes trimesic acid, C5H3(C02H)3.

The Chlorbenzene-sulphonic Acids, CgHjCl.SOjH, are obtained from the
three amidobenzene-sulphonic acids, by treating their diazo-compounds with
hydrochloric acid. The (l, 4)-acid is also produced in the action of SO4H2 upon
CgHj.Cl. The amide of the (i, 2)-acid melts at 182° ; the amide of (i, 3)-acid
at 148°; that of the (l, 4)acid at 143°. The chloride of the (i, 4)-acid, CgH^
Cl.SOjCI, melts at 51°; it yields (i, A,)-C^^C\^, when heated with PCI5.

664 ORGANIC CHEMISTRY.

The Brombenzene-sulphonic Acids, CgH^Br.SOjH, are obtained like the
chlor-acids. The (i, 4)-acid is also formed on heating CjHjBr with SO^Hj or
SO3HCI; the (i, 3)-acid by heating benzenesulphonic acid with bromine to icx3°,
or by the action of Br upon CjH^SOjAg at ordinary temperatures. They are
very deliquescent, crystalline bodies ; the para-acid melts at 88°. All three yield
resorcinol (l, 3), when they are fused with KOH. They form dicyanides, CgH^
(CN)j, by distilling their potassium salts with potassium cyanide or dry yellow
prussiate of potash. Dicarboxylic acids are obtained from these.

Nitrobenzene-sulphonic Acids, C5H4(NOj).S03H. If nitrobenzene be dis-
solved in fuming sulphuric acid, or benzene sulphonic acid in concentrated nitric,
acid, the three nitrobenzene sulphonic acids are produced — the (i,4)-acid in
largest quantity. For their separation they are converted into the amides, CjH^
(N02).S02.NH2, which are then distilled. The free acids are very deliquescent
crystalline masses. Their chlorides melt as follows : (1,2) at 67° ; (1,3) at 60° ;
(l,4) is a liquid. The aOTzV^j fuse : (l,2)atl86°; (i,3)atl6l°; (l,4)atl3i°.
Ammonium sulphide reduces them to the corresponding amidobenzene sulphonic
acids.

Amidobenzene-sulphonic Acids, C5H4(NH2).S03H. They ajre produced
by the reduction of the three nitrobenzene sulphonic acids with ammonium sul-
phide.

The para-acid, commonly called sulphanilic acid, is obtained by
heating aniline (i part) with fuming sulphuric acid (2 parts) to 180°
until SO2 appears. On diluting with water, the acid separates as a
crystalline mass. Its ■ diazo-compounds are changed by hydro-
bromic acid into the corresponding brombenzene-sulpho acids ; by
hydrochloric acid into chlorbenzene sulphonic acids.

The three amido- benzene sulphonic acids dissolve with difSculty in water,
alcohol and ether. The (l, 2)-acid either crystallizes in anhydrous rhombohedra,
or in four-sided prisms containing ^HjO; these do not effloresce. The (1,3)-
acid crystallizes in delicate needles or in prisms with I^H^O, which effloresce.
The sodium amido-benzene-sulphonates yield acetyl derivatives with acetic anhy-
dride {Berichte, 17, 708).

Sulphanilic Acid (i, 4) is obtained by heating (i,4)-and (i, 2)-aniline-phe-
nol-sulphonate : —

^s^^XSOjH.NHj.CgHj = ^^sHi^SOgH + "^eHj-OH,
or aniline ethyl sulphate to 200° : —

It yields aniline and not amidophenol when fused with caustic potash. It crys-
tallizes from hot water in rhombic plates with i molecule HjO ; these effloresce
in the air. They are soluble in 112 parts HjO at 15° (5fr«V.4/(r, 14, 1933). It
yields a considerable quantity of quinone, when oxidiued with MnOj and HjSO^or
chromic acid.

For nitro-aniline-sulphonic acids, consult Berichte, 21, 2579, 3220; 22, 847.

Phenylsulphaminic Acid, CgH5.NH.SO5H (p. 164), is isomeric with the
amidobenzene-sulphonic acids. It results from the action of chlorsulphonic acid

TOLUENE SULfHONiC ACIDS. 665

upon aniline. Its salts are very stable; boiling water does not decompose them.
Boiling water containing a little acid, readily decomposes the free acid into aniline
and sulphuric acid (Berichte, 23, 1653).

Nitrous acid transforms the three amido-benzene-sulphonic acids into the anliy-
drides of the diazobenzene-sulphonic acids (p. 630) : —

Diazobenzene-sulphonic Acid. Anhydride.

The hydrous sulphoacids are not known; they pass at once into anhydrides. It
is rather remarkable that, while otherwise it is only the ortho- compounds of the
benzene derivatives which form inner anhydrides (p. 3S1), all three of the diazo-
benzene sulpho-acids are capable of anhydride formation.

/-Diazobenzene-sulphonic acid (its anhydride) is obtained by dissolving sul-
phanilic acid in sodium hydroxide, adding an equivalent quantity of sodium nitrite
and pouring the mixture into dilute sulphuric acid. The acid separates in needles
that dissolve with difhcully. It exhibits all of the reactions of the diazo-compounds. .'
When heated to 80° with water, the diazo-acid becomes /-phenolsulphonic acid,

/SO TT
^6^4\OH ' '^^s's^ with absolute alcohol, it forms benzene-sulphonic acid. It

is used in the preparation of various azo-dyes.

wz-Diazobenzene-sulphonic acid, Metanilic acid (p. 664), unites with diphehyl-
amlne to yield metanilic yellow.

The action of the diazo-sulphonic acid upon alcoholic H2S, is to substitute the
diazo-group by SH, virith the production of the phenolsulphonic acids, e. g.,

'-6«4\s03H-

The benzene-diazo-sulphonic diazoamido-derivatives (the same as those of ben-
zene carboxylic acids) are not known.

The action of HI upon the nitro-benzene-sulphonic chlorides, CjH^^ gQ ^p,,

produces the sulphimido benzenes, which are nitrodiphenyl disulphides {Berichte,
21, 1099).

Disulphanilic Acid, C5H3(NH2)(S03H)j (i, 4, 2 — NH^ in i), is obtained
by protracted heating of sulphanilic acid to 180° with concentrated sulphuric
acid. The replacement of the amido-group produces metabenzene-disulphonic
acid (p. 663).

Toluene Sulphonic Acids, CjH.,(CH3).S03H. It is chiefly the para-com-
pound, together with some ortlio- and meta {Berichte, 17, Ref. 283), which is
produced by the solution of toluene in sulphuric acid or by the action of chlor-
sulphonic acid upon it. The chloride of the/<j?-a-acid is solid and melts at 69°;
that of the ortho-acid is liquid. When fused with alkali the para-acid yields para-
cresol and para-oxybenzoic acid, the ortho-acid, however, ortho cresol and salicylic
acid. When the former is oxidized with a chromic-acid mixture, it forms para-
sulphobenzoic acid, while the latter passes into ortho-sulphobenzoic acid {Berichte,
20, 2929).

Ammonium carbonate converts the three sulphochlorides into three toluene-
sulphamides, C8H,(CH3).S02.NH2 {Berichte, 21, Ref. 100). Potassium per-
manganate oxidizes these to the corresponding sulphamine benzoic acids,

^^Hi^co' h"' '^Berichte, 21, 242).

Toluene^Disulphonic Acids, C3Hj(CH3)(S03H)2. The six possible iso-
merides are known {Berichte, 20, 350).
56

666 ORGANIC CHEMISTRY.

PHENOLS.

The mono-, di- and tri-hydric phenols are derived by the replace-
ment of hydrogen in the benzenes by hydroxyls : —

C.H^.OH CeH.(OH), C,H,(OH)3.

Phenol. Dioxybenzenes. Tnoxybenzenes.

The phenols correspond to the tertiary alcohols, as they yield
neither acids nor ketones upon oxidation. Their acid nature, dis-
tinguishing them from alcohols, is governed by the more negative
nature of the phenyl group (p. 557). The following are the more
general and most important methods of forming them : —

1. By the action of nitrous acid upon the aqueous solution of the
amido-compounds, or by decomposing the diazo-derivatives with
boiling water (p. 632).

The sulphuric acid salts of the diazo-compounds are particularly well adapted
to this end ; the nitric acid salts tend to yield nitro-phenols.. It is best to dissolve
the amidb-derivatives in dilute sulphuric acid (2 equivalents), add aqueous potas-
sium nitrite (I molecule), and boil the strongly diluted solution until the disen-
gagement of nitrogen ceases.

2. Fusion of the sulphonic acids with potassium or sodium
hydroxide : —

CeHs.SOjK -I- KOH = CeH^.OH -1- SO3K,,
^'^KsoX + ^OH = C«H,/gg' + SO3K,.
Here the sulpho-group disappears as a sulphite (p. 152).

The experiment is executed in a silver dish at higher or lower temperatures, the
fusion supersaturated with sulphuric acid, and the phenol extracted by shaking
with ether.

In fusing sulphonic acids or phenols containing halogens, the latter are also
replaced with formation of polyhydric phenols : —

CsH^.CLSOgK -f 2KOH = C6Hi(0H), -j- SOjKj + KCl,
CeHjCl.OH -j- KOH = CeH^COH), -f KCl.

Occasionally the sulpho-group splits off as sulphate and is replaced by hydrogen;
thus, cresolsulphonic acid yields cresol.

3. Small quantities of phenol can be obtained from benzene by the action of
ozone, hydrogen peroxide (palladium hydride and water), and by shaking with
sodium hydroxide and air [Berichte, 14, 1 144).

4. The halogen benzene substitution products do not react with
alkalies ; but if nitro-groups are present at the same time, the halo-
gens are replaced even by digesting with aqueous alkalies — this will
occur the more readily if the hitro-groups be multiplied. For ex-

PHENOLS. 667

ample, ortho- and para-chlornitro-benzene (but not meta) yield the
corresponding nitro-phenols (p. 676), when they are heated to 120°
with sodium hydroxide ; the dinitro-chlorbenzenes even react when
boiled with carbonates, and the trinitro-chlorbenzene even with
water.

/-Nitrophenol-ethers, CgH4(N02).OR, are produced on boiling /-chlornitro-
benzene with caustic soda and 60 per cent, alcohol ; if absolute alcohol be applied
there is simultaneous reduction and formation of chlorazobenzene (Berichte, 15,
loos).

The amide-group in the nitroamido-derivatives can also be replaced by hydroxyl
on boiling witii aqueous alkalies; ortho- and para-nitranilines, CgHj(N02).NH2
(not meta), yield theu: corresponding nitrophenols. The ortho-dinitro-products
react similarly (p. 587).

5. The dry distillation of salts of the oxy-acids of the benzene
series with lime (p. 570): —

CeH^COHj.CO^H = CjH^.OH + COj,
Oxybenzoic Acid. Phenol.

C,H,(OH)3.CO,H = C^H (OH)3 + CO^.

Gallic Acid. Pyrogallol or Pyrogallic Acid.

6. Dry distillation of various complex carbon compounds, e. g.,
wood and coal. To isolate the phenols from the coal tar, shake
the fraction boiling at 150-209°, with aqueous potash, separate the
aqueous solution from the oil containing the hydrocarbons, and
saturate it with hydrochloric acid. The separated phenols are
purified by fractional distillation.

Wood-tar oils {creosote) consist of a mixture of different phenols and their
ethers; the portion, 'boiling at 180-300°, contains phenol, CgHj.OH, para-cresol,
C6H4(CH3).OH, phlorol, C5H3(CH3)j.OH, also guaiacol, CeH,(0.CH3).0H,
creosol, C5Hg(CH3).(O.CH3).OH, and the dimethyl ether of pyrogallic acid,
CjH3(OH)3, and methyl- and .propyl pyrogallol (Berichte, 14, 2005).

7. The synthesis of the higher phenols by introduction of alkyls
into the benzene nucleus (p. 570) takes place readily on heatiiig
the phenols with alcohols and ZnClj to 200° {Berichte, 14, 1842 ;
17, 669):—

C.H^.OH + CjH^.OH = CeH,(C,H5).0H -|- H,0.

Alkyl ethers of the phenols are simultaneously produced; methyl alcohol
yields methyl-phenol, CjHj.O.CHj. Magnesium chloride [Berichte, 16, 792)
and primary alkali sulphates {Berichte, 16, 2541) possess the same condensing
power as ZnCl,. Phenol and resorcinol condense to ketones, e. g., dioxybenzo-
phenone, Celi^{0'ti).CO.C^B.^.OYi [Berichte, 16, 2298), when heated with
salicylic acid and tin chloride.

8. Many benzene derivatives are transposed in the animal organism into phe-
nols; thus, benzene yields phenol; brombenzene, bromphenol; aniline, amido-
phenol and phenol hydroquinone. Different phenols are found already formed as
phenol sulphuric acids (p. 670) in the urine of mammals.

668 ORGANIC CHEMISTRY.

The phenols are the analogues of the tertiary alcohols, but
possess a more acid character (p. 666). The hydrogen of their
hydroxyl can be readily substituted by metals, by the action of
bases, chiefly of the alkalies. Carbon dioxide separates the phenols
again from these salts. The entrance of negative groups into the
benzene nucleus increases the acid nature of the phenols. Thus
trinitrophenol manifests the properties of an acid, as it decomposes
carbonates. The hydroxyl-hydrogen of the phenols can also be
replaced by alcohol and acid radicals.

The alcohol-ethers are formed : by the action of the alkyl iodides
upon the salts of the phenols (chiefly the silver salts), or by heating
a mixture of the alkali salts of the phenols with an excess of alkyl
sulphates, in aqueous or alcoholic solution (JBerichte, ig, Ref.
139):—

C.Hj.OH + C2H5.I + KOH = C5H,.O.C,H5 + KI + H,0;

and by the dry distillation of the phenol ethers of the oxy-acids with lime : —

^«H«\CO,H = CeHa-O.CH, + CO,.

Anisic Acid, Methyl Flienol.

Boiling alkalies do not alter the alcohol ethers. When, however, they are
heated with hydriodlc or hydrochloric acid, they split up into their components : —

CeH^.O.CH, + HI = C.H^.OH + CH3I.

The acid esters are obtained by acting with acid chlorides or
anhydrides upon the phenols or their salts ; also by digesting the
phenols with acids and POCI3. On boiling with alkalies or even
with water, they, like all esters, break down into their components.

To effect the substitution of all the hydroxyl-hydrogen atoms in the polyhydric
phenols by acetyl groups, it is recommended to heat them with acetic anhydride
and sodium acetate.

Phosphorus sulphide converts the phenols into thio-phenols : —

SCeHj.OH + P.Ss = SCeH^-SH + P,0,.

■ The phosphorus haloids replace the hydroxyls of the phenols by
halogens, forming substituted benzenes. When heated with zinc
dust the phenols are reduced to hydrocarbons. The anilines result
on heating with zinc-ammonium chloride (compare p. 593).

On adding phenols (mono- or polyhydric) to a solution of KNOj (6 per cent.)
in concentrated sulphuric acid, intense colorations arise; with common phenol we
get first a brown, then green, and finally a royal-blue color (Reaction of Lieber-
mann) (see Berichte, 17, 1875). Dyes are produced in this manner; their char-
acter is as yet unexplained. They have been called dichroines (Berichte, 21,
249). The phenols afford similar colors in the presence of sulphuric acid, with

' MONOHYDRIC PHENOLS. 669

diazo-compounds, and nitroso-derivatives (p. 636). Ferric chloride imparts color
to the solutions of most phenols. Mercury nitrate, containing nitrous acid, colors
.nearly all the phenols red (Reaction of Plugge) [Berichie, 23, Ref. 202).

The hydrogen of the benzene residue in phenols can be replaced,
further, by the halogens and groups NO2, SO3H, etc. In the alco-
hol-ethers of the nitro-phenols (as with the acid esters) we can
replace the OH by NHj, on heating with alcoholic ammonia
(P- 593) :—

CeH,(N02).O.CH3 -f NH3 = CeH,(NO,).NH, + CH3.OH.

The phenols and their halogen products may be converted into
oxy-acids by the action of sodium and carbon dioxide (see aromatic
series) : —

CgHs.OH + CO2 = C6H^(OH).C02H.

Oxyaldehydes, C5H^(OH).CHO, are produced from phenols, chloroform and
caustic soda, and oxyacids (see these) from phenols and carbon tetrachloride.
The diazo- yield azo-compounds with phenols — the tropseoline dyes belong to this
class (p. 644). Dyestuffs belonging to the aurine series, and derived from tri-
phenylmethane, CH(CgH5)3 (see this), are obtained from the phenols by their
action upon benzotrichloride, C5H5.CCI3. The so-called phthalcins are combina-
tions of phthalic acid and the phenols.

MONOHYDRIC PHENOLS.

Phenol, CbHj.OH.
Cresols, CsH^.CH3(OH).
Xylenols, C6H3(CH5)j.OH, etc.

Phenol, CsHs-OH (Benzene Phenol, Carbolic Acid, Creasote).
This was first discovered (1834) in coal-tar, by Runge. It is
obtained from amidobenzene, from benzene-sulphonic acid, from
the three oxy- benzoic acids, etc., by the methods previously de-
scribed. It occurs already formed in Castoreum and in the urine
of the herbivorse.

Commercial phenol is a colorless crystalline mass, which gradu-
ally acquires a reddish color, and deliquesces on exposure to the
air. Pure phenol crystallizes in long, colorless prisms, melts at
42°, and boils at 183° ; its specific gravity at 0° is 1.084. It pos-
sesses a characteristic odor, burning taste, and poisonous and anti-
septic properties. It dissolves in 15 parts water at 20°, and very
readily in alcohol, ether and glacial acetic acid. Ferric salts im-
part a violet color to its neutral solutions. Bromine water precipi-
tates tribromphenol from even very dilute solutions. Diphenols,
Ci2H8(OH)2, derivatives' of diphenyl (see this), are produced on
ftising phenol with caustic potash.

670 ORGANIC CHEMISTRY.

Potassium Phenylate or Phenoxide, C5H5.OK, is obtained by dissolving phenol
in potassium hydroxide. It crystallizes in delicate, readily soluble needles. CO^
separates phenol from it, which, therefore, is insoluble in alkaline carbonates..
Barlya, lime, and litharge form similar compounds.

Phenacetein, Phenacetolin, CjjHj^O, {Berichte, 15, 2907), is obtained by heat-
ing phenol with acetic acid and zinc chloride; This compound is employed as an
indicator in alkalimetry [Berichie, 14, 2306).

ACID ESTERS OF PHENOL (p. 668)— ETHEREAL SALTS.

Phenylsulpkuric Acid, C5H5.O.SO3H, is not known in a free state; when
liberated from its salts by concentrated hydrochloric acid, it immediately breaks
down into phenol and sulphuric acid. Its potassium salt, C5H5.O.SO3K, forms
leaflets, not very soluble in cold water, and occurs in the urine of herbivorous
animals, and also in that of man and the dog after the ingestion of phenol. It is
synthetically prepared, like other phenols, on heating potassium phenoxide with
an aqueous solution of potassium pyrosulphate (Berichte, 9, 1715).

The phenyl sulphuric acids are very stable in aqueous and alkaline solution;
upon digesting with mineral acids, however, they are very rapidly decomposed.
When potassium phenylsulphate is heated in a tube it passes quietly into /-potas-
sium sulphonate : —

CJis.O.SOjj.OK ' yields CgH

/OH

«"*\SOjOK-

The phenol esters of phosphoric acid are produced by the action of PCI5 upon
phenol (together with chlorides) : —

I'ola^H, ^°{??C,H,), -""l PO(O.C,H,)3.

The tripkenyl ester is easily formed on boiling phenol with phosphorus oxy-
chloride (Berichte, 16, 1763). It is crystalline, melts at 45°, and boils near 400°.
Distilled with potassium cyanide it yields benzonitrile, CgHj.CN.

Consult Berichte, 18, 1700, upon the phosphoric acid esters of the higher
phenols and their conversion into nitriles.

At the ordinary temperature carbon dioxide converts dry sodium phenate (at
ordinary pressure) into the sodium salt of Phenylcarbonic Acid (Berichte 18,
Ref. 440) : —

CsH^.ONa -f COj = CjHj.O.CO^Na.

This is a white hygroscopic powder, decomposed again by water. When heated
under pressure to 120-130° sodium salicylate results : —

C.H^.O.CO.Na yields CeH,/°^^^^,

just as phenolsulphonic acid is obtained from phenylsulphuric acid (see above).
When heated to 190° with sodium phenate sodium phenyl carbonate yields di-
sodium salicylate and phenol : —

C^Hj.O.COjNa -j- CjHj.ONa = CjH,(ONa).COjNa + CeHj.OH.

The carbonic acid ester. Phenyl Carbonate, CO(O.CgH5)2, is produced on
heating phenol and phosgene gas, COClj, to 150°. It is readily obtained by

PHENOL ALCOHOLIC ETHERS. 671

leading phosgene gas into the aqueous solution of sodium phenylate {Joum.
pract. Chem., 27, 139, Berichte, 17, 287). It crystallizes from alcohol in shining
needles, and melts at 78°. It yields sodium salicylate (see this) when heated to
200° with sodium hydroxide. Urea results if it be heated with ammonia, and by
using amine bases, instead of ammonia, phenylated ureas will constitute the
product (Berichte, 23, 694).

Mixed carbonates containing phenol and alkyls, e. g., phenyl-ethyl carbonate,
CO,(C2H5)(CgH5), are produced by the action of chlor-formic esters upon the
sodium salts of the phenols.

The acetic ester, CgHg.O.CjHjO, is obtained by boiling the phosphoric ester
with potassium acetate, and is an agreeable-smelling liquid, boiling at igo°.

Phenyl-glycoUic Acid, CH2<' p^ Vr ^' phenyl oxy-acetic acid (isomeric with

mandelic acid), is produced by heating monochloracetic acid with potassium
phenate to 150°. Long, silky needles, melting at 96°. All other phenols react
analogously.

The action of sodium phenate upon chloracetoacetic ester produces : —

Phenoxyl-acetoacetic Ester, C-IL.O.CH^' p^' p A , a dark oil, that is con-

densed by sulphuric acid, with water exit, to methylcoumarilic ester. Other
coumarilic compounds are analogously produced (see these and Berichte, ig,
1291).

/o r* TT
Phenyl Ethyl Oxalic Ester, €202^ n C*H*' '°'^'"^'^ W *^^ action of chlor-

oxalic ester (p. 405) upon phenol, is an oil boiling at 236°, and is slowly decom-
posed by water into phenol, oxalic acid and alcohol.

The succinic ester, CjH4(C02.CgH5)2, from phenol and succinyl chloride, forms
shining leaflets, melts at ll8°, and boils at 330°.

Phenyl-allophanic Ester, CO^ NH^CO C H (P' 393)' '^ produced by conduct-
ing cyanic acid vapors into anhydrous phenol. A crystalline mass, decomposing
at 150° into phenol and cyanuric acid.

Phenyl-ortho-formic-ester, CH(O.C8H5)j, is formed by boiling phenol with
sodium hydroxide and chloroform (as a by-product in the formation of oxybenzal-
dehyde). It crystallizes in white needles, melts at 71° and distils at 265°, under
50 ram. pressure. See Berichte, 18, 1679, for the phenol silicates.

PHENOL ALCOHOLIC ETHERS (p. 668).

Methyl Phenyl Ether, CjHj.O.CHj, Anisol, is produced by heating phenol
with potassium and methyl iodide or potassium methyl sulphate in alcoholic solu-
tion ; by distilling anisic or methyl salicylic acid with lime or baryta (p. 668) ;
or by leading methyl chloride into sodium phenoxide at 200° (Berichte, 16,

2513)-

It is an ethereal-smelling liquid, boiling at 152°; its specific gravity at 15° is
0.991. Heated to 130° with hydriodic acid it decomposes into phenol and methyl
alcohol. It is not reduced by zinc dust.

Bromine converts it into substitution products: hromanisol, CjH^Br.O.CHg,
boils at 223°; dibromanisol crysiaXWzes in rhombic plates, melts at 59° and boils
at 272° ; tribromanisol melts at 87° and sublimes. Further action of bromine
produces bromanil, CgBr^Oj.

Nitric acid converts anisol into two mono-nUroanisols (l, 4) and (l, 2).

672 ORGANIC CHEMISTRY.

Ethyl Phenyl Ether, (CgHs).© C^Hj, Phenetol, is obtained from phenol
and eihyl salicylic acid. It is an aromatic-smelling ether, boiling at 172°. The
isoamyl ether bnils at 225°.

Ethylene Phenyl Ether, (0,5115.0)2.02114, is formed from ethylene bromide
and pota'-sium phenylate. It consists of leaflets, melting at 95°.

Phenyl Ether, (CgH,),©, Phenyl Oxide, is produced by distilling copper
benzoate (together with benzoic phenyl ether) and digesting diazolienzene sul-
phate with phenol; also by heating phenol with zinc chloride to 350°, or better,
wi h aluminium chloride (Berichte, 14, 189). It crystallizes in long needles, pos-
sesses an odor resembling that of geraniums; melts at 28°, and boils at 252°. It
dissolves readily in alcohol and ether. It is not reduced on heating with zinc
dust or hydriodic acid.

Thiophenol, C5H5.SH, phenyl mercaptan, is obtained by letting phosphorus
pentasulphide act on phenol or sodium benzene sulphonate; or by the action of
zinc and sulphuric acid upon CgHj.SOjCl (p. 660). It is most readily prepared
by distilling sodium benzene-sulphonate with potassium sulphydrate (Berichte, 17,
2080). It is a mobile, ill-smelling liquid, boiling at 168°; its specific gravity at
14° is 1.078. It dissolves readily in alcohol and ether. Like the mercaptans, it
reacts readily with metallic oxides. The mercury compound, (CjH5.S)2Hg,
crystallizes fr^m alcohol in shining needles. Silver, mercury and lead salts pre-
cipitate the alcoholic solution of thiophenol.

Phenyl mercaptan combines with a-, /3- and y-ketonic acids, yielding derivatives
resembling mercaptol (p. 306 and Berichte, 19, 1787). Esters of phenyl Ihioformic
acid, CgHj.S.COjR {Berichte, 19, 1228) result from the action of thiophen) I-zinc
and chlorcarhonic esters.

Phenyl Dithiocarbonic Esters, C5H5.S.CS.OR, are produced when benzene
diazo-chlorides act upon xanthic esters. They decompose at 200° into COS and
thiophenols {Berichte, 21, Ref. 915).

Phenyl Sulphide (05115)28, Benzene sulphide, is formed by distilling phenol
with P2S5 (along with thiophenol), and in the dry distillation of sodium benzene
sulphonate, as well as in the action of benzene-diazochloride upon sodium thio-
phenate {Berichte, 23, 2471). A colorless liquid, with an odor resembling that of
leeks ; boils at 292°, and has a specific gravity of 1. 12. Nitric acid converts it into
phenylsulphone.

Phenyl Bisulphide (05115)282, results from the oxidation of thiophenol with
dilute nitric acid, and by the action of iodine upon aqueous potassium thiophenate :

2C5H5

also, when an alcoholic solution of benzene sulpho-chloride is reduced with potas-
sium cyanide.

It crystallizes from alcohol in shining needles, melting at 60°. Nitric acid
oxidizes it to benzene sulphonic acid, and nascent hydrogen converts it into thio-
phenol. The same occurs by the use of KjS (Berichte, 19, 3129).

Phenyl-disulphides, containing two different radicals, result from the action of
bromine upon a mixture of two thiophenols (Berichte, 19, 3132; 20, 189) : —

C5H5.SH + 0,H,(OH,).SH + Br^ = c^Yi^^l^/^'^ + ^H^""-

PHENOL SUBSTITUTION PRODUCfS. 673

PHENOL SUBSTITUTION PRODUCTS.

The introduction of halogen atoms considerably increases the
acid character of phenol ; thus, trichlorphenol readily decomposes
the alkaline carbonates. When fused with potassium hydroxide
the halogen is replaced by the hydroxyl group (p. 667):

CjH^CLOH + KOH = C(,H^(0H)2 + KCl.

In this reaction it frequently occurs that not the corresponding
isomerides, but rather, the more stable derivative results ; for ex-
ample, all the bromphenols yield resorcinol.

Chlorine and bromine react readily ; this is exemplified in bro-
mine precipitating tribromphenol directly upon its introduction into
phenol solutions. The iodo-derivatives are formed by adding
iodine and iodic acid to a dilute potassium hydroxide solution of
phenol : —

5C,H,0 + 2I, + IO3H = sCeHJO -1- 3H,0,

or by the action of iodine and mercuric oxide (p. 91). Di-iodo-
phenol is the chief product in the latter case.

Substituted phenols are obtained indirectly : I, from substituted anilines by the
replacement of NH.j by OH, which may be brought about through the diazo-
compounds ; 2, from the nitrophenols by replacing the nitre-group with halogens
(effected through the amido- and diazo-derivatives) ; 3, by distilling substituted
oxyacids with lime or baryta : —

CeH3Br/°^^jj = C^H^BnOH + CO,.
Bromsalicylic Acid.
Sodium amalgam causes the replacement of the halogen atoms by hydrogen.-

Chlorphenols, CsH^Cl.OH. The para- and ortho-derivatives are produced
by leading chlorine into boiling phenol ; they can be separated by fractional dis-
tillation. The three chlor-compounds may be obtained perfectly pure from the
corresponding chlor-anilines (from the chlor-nitro-benzenes). (l, 2)-Chhrphe-
nol (also produced from volatile ortho nitro-phenol) boils at 176°, solidifies
at — 12°, and melts at +7°. It yields pyrocatechin when fused with KOH.
(i, ■^-Chlorphenol,ixam.{i, 3)-chlor-aniline, melts at 28.5°, and boils at 212°-
(i, n^-Chlorphenol (para) consists of colorless prisms, which acquire a red color
on exposure to the air, melt at 37° (41°) and boil at 217°. Hydroquinone is
produced when it is fused with caustic potash. The three chlorphenols have a
very penetrating, adhering odor.

Dichlorphenol, CgHgCl^.OH, from phenol (1,2, 4 — OH in i), melts at
43° and boils at 210°. It yields (i, 2, 4)-trichIorbenzene with PClg. ' Trichlor-
phenol, CgHjCla.OH (I, 3, 5, OH) (compare p. 589), obtained by acting on
phenol with chlorine, melts at 68°, boils at 244°, and reacts acid. Pentachlor-
phenol, CgCl^.OH, formed by the chlorination of phenol in presence of SbCl,,
melts at 187°.°

674 ' ' ORGANIC CHEMISTRY.

Bromphenols, CsH^Br.OH {Annalen, 234, 129). On conducting bromine
vapors into phenol, or in brotninating the glacial acetic acid solution of phenol we
obtain chiefly (I, 4)- and {I, 2)-nionobromphenol ; under certain conditions it
appears that (1,3) is also produced. They are obtained pure from the brom-
anilines.

(i, 2)-Bromphenol, from (l, 2)-bromaniline and from (l, 2)-nitrophenol, is a
liquid, boilmg at 195°. (l, zYBromphenol, from (l, 3)-bromaniline, melts at 32-
33°, and boils at 236°. (i, ^)-Bromphenol is formed in largest quantity when
phenol is treated with bromine, and has also been obtained from (i, 4)-brom-
aniline and from bromsalicylic acid. It consists of large crystals, melting at 66°
(66.4°) and boiling at 238°. PBrs converts it into ^l, 4)-dibrombenzene.

Dibromphenol, CgHgBrj.OH (1,2, 4 — OH ra i), from phenol, melts at
40°. Tribromphenol, CeHjBr3(0H) (i, 3, 5, OH), is directly precipitated
from aqueous phenol solutions by bromine water. It crystallizes from alcohol in
silky needles, melting at 92°. PBrg converts it into tetrabrombenzene, melting at
98°. Nitric acid converts it into picric acid. Tetrabromphenol, CsHBr^OH,
melts at I20°; Pentabromphenol, CgBrsOH, at 225°.

lodophenols, CgH^T.OH. When phenol is acted upon by iodine and iodic
acid three mono-iodo-phenols are said to be formed; of these the ortho- and
meta- volatilize with steam, the para- does not {Berichte, 6, 1251).

(1, ■2.')-Iodophenol is obtained from (i, 2)-amido-phenol and from iodosalicylic
acid. It is also produced when iodine acts upon sodium phenoxide (Berichte, 16,
1897). It melts at 43° and when fused with KOH yields pyrocatechin (at 200°)
and resorcinol. {1, ^)-Iodopkenol,bom. phenol, (l, 4)-amidophenol and (1,4)-
iodo-aniline, melts at 89°, and when fused with KOH forms hydroquinone at 160°,
but resorcinol at higher temperatures.

NIXROSO-DERIVATIVES OF PHENOL.

The nitrosophenols, analogous to the nitroso-benzenes (p. 591),
were first made by the action of nitrous acid upon phenols, and
again they are obtained from the quinones by the action of hydroxyl-
amine, and may, therefore, be considered as isonitroso-derivatives
(p. 191), or quinoxiraes (see quinone). In accordance with their
mode of formation they have the formulas of nitrosophenols or of
quinoximes (Goldschmidt, Berichte, 7, 213, 801): —

OH O O

CeH / and C,H,^ or C,H / |

\nO ^N.OH . ^N.OH

Nitrosophenol. Quinoxime.

These formulas are probably tautomeric. The formation of qninone-dioxime
argues in favor of the formula ascribed to quinoxime (p. 675) ; it is also supported
by the deportment of the two nitrosonaphthols with hydroxylamine, and their
ethers when reduced (see nitrosonaphthols, Berichte, 18, 571); further, by the
action of methyl hydroxylamine upon naphthoquinones {Berichte, 18, 2224), by
the feeble basic character of the nitrosophenols [Berichte, 18, 3198), and the for-
mation of hypochlorous esters, C5H4(0).NOCl, when acted upon by bleaching
lime [Berichte, ig, 280). An argument in favor of the nitrosophenol formula is
found in their oxidation to nitrophenols, and subsequent reduction to amido-
phenols.

NITROSOPHENOL, QUINOXIME. 675

The so-called nitrosophenols are formed : —

I. By the action of nitrous acid upon the phenols : —

CeHj.OH + NOjjH = C5H4(NO).OH + H^O.

Phenol is dissolved in a dilute allcaline hydroxide, the equivalent amount of po-
tassium nitrite added, the solution cooled with ice, and gradually supersaturated
with dilute sulphuric or acetic aCid (Berichte, 8, 614).

Instead of nitrous acid we may employ the action of nitro-sulphuric acid,

SOj^ q'tt , upon aqueous phenols {Annalen, 188, 3S3).

In both reactions nitrous acid is liberated and occasions the production of con-
siderable resin. Hence, it is advisable to employ the nitrites of heavy metals,
which are decomposed by the phenols themselves (Berichte, 16, 3080).

In many cases the action of amyl nitrite upon sodium phenoxides is adapted
for this purpose.

It is noteworthy that while the mono-hydric phenols yield only mono nitroso-
compounds, two nitroso-groups directly enter the divalent phenols of the meta-
series (lilie resorcinol and orcinol).

' 2. By the action of HCl-hydroxylamine upon quinones in aqueous or alcoholic
solution. Free hydroxylamine reduces the quinones to hydroquinones (Berichte,
17, 2061).

/-Nitrosopheixol, Quinoxime, C8H4(NO).OH, or

CeHi"^^ (-.TT. Besides the general methods just mentioned, it is

also obtained by a peculiar decomposition of nitroso-dimethyl- or
diethyl aniline (p. 602) with sodium hydroxide : —

C6H^(NO).N(CH3)3 + NaOH = CeH^(NO).ONa + NH(CH3)j.

It is produced, further, by the action of hydroxylamine hydro-
chloride upon an aqueous solution of quinone, CsHiOj (see above).

Preparation. — It is made from phenol by the action of NO^K and acetic acid
{^Berickte, 7, 967), or nitroso-sulphuric acid {Annalen, 188, Tfxi; Berichte, 21,
429). Its production from nitroso-dimethyl-aniline is more convenient. The
pure (free from alcohol) hydrochloride of the latter is introduced into boiling,
dilute sodium hydroxide, the dimethyl-amine formed is distilled off, the residue
acidified with dilute sulphuric acid, and then shaken with ether {Berichte, 7, 964,
and 8, 622). We can easily obtain sodium nitrosophenylate by adding phenol (i
molecule), and then amyl nitrite (i molecule) to a concentrated solution of sodium
ethylate (l molecule), and allowing the whole to evaporate over sulphuric acid
{Berichte, 17, 400). The free nitrosophenol is obtained by decomposing the
sodium salt with dilute sulphuric acid {Berichte, 17, 803).

Pure nitrosophenol crystallizes from hot water in colorless, deli-
cate needles, which readily brown on exposure, and from ether it
separates in large, greenish-brown leaflets. . It is soluble in water,
alcohol and ether, and imparts to them a bright green color. When
heated it melts with decomposition, and deflagrates at 110-120°.
The sodium salt crystallizes in red needles, containing two mole-

676 ORGANIC CHEMISTRY.

cules of water ; salts of the heavy metals throw out dark, amorphous
precipitates.

Nitric acid and potassium ferricyanide in alkaline solution, oxidize /-nitroso-
phenol to /-nitrophenol. Tin and hydrochloric acid reduce it to / amidophenol.
Hydrochloric acid converts it into dichloramido-phenol. With niuous acid and
with hydroxylamine, it yields diazo-phenol : —

CeH^(OH)NO + NH,.OH = C6Hi(0H).Nj.0H + H,0.

In a similar manner it forms azo-compounds with the amines (p. 641); these
are obtained, too, on fusion with caustic alkali. On adding a little concentrated
sulphuric acid to a mixture of nitrosophenol and phenol, we obtain a dark red
coloration, which changes to dark blue upon adding caustic potash (p. 668).

Other phenols, like naphthol, resorcinol and orcinol, yield similar nitroso-deriva-
iives. These same products can also be prepared from the corresponding quinones,
by the action of hydroxylamine hydrochloride {Berichte, 17, 2060).

When hydroxylamine hydrochloride acts upon /-nitrophenol (or upon quinone
or hydroquinone in hydrochloric acid solution) we get Quinone Dioxime, HO.N :
C15H4 : N.OH (^Berichte, 20, 613), crystallizing from hot water in yellow needles.'
It is not as acid as nitrosophenol, and decomposes on heating to 240°. Stannous
chloride and hydrochloric acid reduce it to /phenylene diamine, and by ferri-
cyanide of potassium it is oxidized in alkaline solution to /-dinitrosobenzene
(p. 591). The formation of quinone-dioxime confirms the assumption of nitroso-
phenol being a monooxime of quinone (p. 674).

NITRO-PRODUCTS OF PHENOL.

The phenols, like the anilines, are very readily nitrated. The
entrance of the nitro-groups increases their acid character very con-
siderably. All nitrophenols decompose alkaline carbonates. Tri-
nitrophenol is a perfect acid in its behavior; its chloranhydride,
C6H2(N02)3C1, reacts quite readily with water, re-forming trinitro-
phenol (p. 667). The benzene nucleus of the nitrophenols is
capable of ready substitution with the halogens ; whereas the nitro-
hydrocarbons are chlorinated with difficulty.

Dilute nitric acid converts phenol into ortho- and para-mono-
nitrophenol (in the cold it is chiefly the para-compound which is
formed).

Preparation. — Gradually add one part phenol to a cooled solution of two parts
of nitric acid f specific gravity 1.34) in four parts of water. The oil which
separates is washed with water and distilled with steam, when the volatile (l, 2)-
nitrophenol distils over, while the non-volatile (i, 4)-nitrophenol remains. It is
extracted from the residue by boiling with water.

o- and /-Nitrophenols are obtained by heating the corresponding
chlor- and brom-nitrobeiizenes with caustic potash to 120°, whereas
»«-nitrobenzene does not react under similar circumstances (p. 588).
Ortho- and para-nLtrophenols are likewise produced from the cor-

■ TRINITROPHENOLS. 6'J'j

responding nitranilines by heating with alkalies (p. 598). w-Nitro-
phenol is formed from w-nitraniline (from ordinary dinitrobenzene)
by boiling the diazo-compound with water. See Berichte, 19,
2979, for the benzoyl derivatives of the nitrophenols.

Mononitrophenols, C6H40H(NOj). The volatile orihonitrophenol (i, 2)
crystallizes in large yellow prisms, is but slightly soluble in water, and readily
volatilizes with steam. It has a peculiar odor, and sweetish taste; melts at 45°,
and boils at 214°. (i, 2)-Chlornitro.benzene is obtained from it by PCI5. Its
sodium salt is anhydrous, and forms dark red prisms. The methyl ether, CgH^
(NOj).O.CH3, ™£l's at + 9°, and boils at 265°. Caustic potash does not decom-
pose it.

(i, ■^-Nitrophenol, from (i, 3)-nitraniline, is rather readily soluble in cold
water, forms yellow crystals, melts St 96°, and is not volatilized with steam. Its
methyl ether melts at 38° and boils at 254O.

(i, 4)-iV!/n^^if»o/ crystallizes from hot water in long, colorless needles, which
become red on exposure. It is colorless and melts at 1 14°. PCI5 converts it
into (i, 4)-chIornitrobenzene. The potassium salt crystallizes in yellow needles
with two molecules of water. The methyl ether melts at 48°, and boils at 260° ;
it forms (l, 4)-nitraniline when heated with ammonia. Nitrophenol can, on the
one hand, be changed to quinone, on the other, into anisic acid.

Bromine converts /-nitrophenol into dibrom-/-nitrophenol, CgHjBr^/^JVxT^

(l, 2, 4, 6, OH in l), melting at 141°. Thisyields Dibrom-/-amido-phenol,
when reduced with tin and hydrochloric acid. The latter (its SnCl^-salt) is

,NC1
converted by bleaching lime into dibrom-quinone-chlorimide, CJ^^r^(^ \ ,

which yields indophenol dyestuffs (see quinone chlorimidesj with phenols.

a-Dinitrophenol, C5H3(N02)2.0H (i, 2, 4 — OH in i), is formed by the
direct nitration of phenol, as well as of (l, 2)- and (l, 4) -nitrophenol; by boiling
a-dinitro-chlor- and dinitro-brom-benzene (p. 589) with alkalies, and (together
with ;3-dinitrophenol) by oxidizing metadinitrobenzene with alkaline potassium
ferricyanide. It crystallizes from alcohol in yellow plates, and melts at 114°.
PCI 5 changes it to dinitrochlorbenzene. Its methyl ether melts at 86°, and is
saponified by boiling alkalies. The ether is transformed into a-dinitraniline by
heating with ammonia. From this.(i, 3)-dinitrobenzene may be prepared by re-
placing the amido group by hydrotjen (through the diazo-compound).

/3-DinitTophenol (i, 2, 6 — OH in i) is produced with the former in the nitra-
tion of (i, 2)-nitrophenol. It yields needles, melting at 64°. By replacing its
OHgroup with hydrogen it passes into (i, 3) dinitrobenzene.

Further nitration converts both dinitrophenols into picric acid. Three isomeric
dinitrophenols are obtained by the nitration of (i, 3)-nitrophenol ; these melt at
104°, 134° and 141°. Further action of nitric acid converts them into trinitro-
resorcinol.

Trinitrophenols, C6H2(N02)3.0H. Picric Acid is obtained
by the nitration of phenol, of (i, 2)- and (i, 4")-nitrophenol, and
of the two dinitrophenols; also, by the oxidation of symmetrical
trinitrobenzene with potassium ferricyanide. Its structure is there-
fore I, 2, 4, 6 (OH. in i) (p. 589).

Picric acid is produced in the action of concentrated nitric acid

678 ORGANIC CHEMISTRY.

upon various organic substances, like indigo, aniline, resins, silk,
leather and wool.

Preparation. — Add phenol (l part) very gradually to concentrated nitric acid,
slightly warmed. The reaction proceeds with much energy, and disengages
brown vapors. Next add three parts fuming nitric acid and boil for some time,
until the evolution of vapors ceases. The resulting resinous mass is boiled with
hot water. To purify the picric acid obtained, convert the latter into its sodium
salt, and to its solution add sodium carbonate when sodium picrate will separate in
a crystalline form.

Picric acid crystallizes from hot water and alcohol in yellow leaf-
lets or prisms which possess a very bitter taste. It dissolves in 160
parts of cold water and rather readily in hot water. Its solution im-
parts a beautiful yellow color to silk and wool. It melts at 122.5°,
and sublimes undecomposed when carefully heated. The potassium
salt, C6H2(N02)30K, crystallizes in yellow needles, which dissolve
in 260 parts of water at 15°. The sodium salt is soluble in 10 parts
water at 15°, and is separated from its solution by sodium carbon-
ate. The ammonium salt consists of beautiful, large needles, and
is applied in explosive mixtures. All the picrates explode very
violently when heated or struck.

Phosphorus pentachloride converts picric acid into trinitro-chlor-
benzene, C6H2(N02)3C1 (p. 590), which reverts to picric acid on
boiling with water.

The methyl ester of picric acid is also produced in the nitration of anisol (p.
671) and crystallizes in plates, melting at 65°, and subliming. Alcoholic potash
saponifies it. The ethyl ester consists of colorless needles, which brown on expo-
sure, and melt at 78.5°.

Picric acid forms beautiful crystalline derivatives with many benzene hydro-
carbons, e.g., benzene, naphthalene and anthracene. The benzene derivative,
^6H2(NOj)30H.C5He, crystallizes in needles, melting at 85-90°. In dry air or
with hot water it decomposes into its components.

The so-called isopicric acid, obtained by the energetic nitration
of (i, 3)-nitrophenol, is triiiitroresorcinol, C6H(NOj)s.(OH)2(styph-
nic acid).

Picric acid is converted by potassium cyanide into the potassium salt of isopur-
puric or picrocyaminic acid, CgHgNjOj, which is not stable in a free state. To
obtain the salt the hot solution of 1 part picric acid in 9 parts of watet is poured
gradually into a solution of two parts of potassium cyanide in four parts of water,
at a temperature of 60°. The liquid assumes a dark red color, and when it cools
a crystalline mass separates, which is washed with cold water and recrystallized
from hot water.

The potassium^ salt, CgH^NjOjK, crystallizes in brown leaflets with green-
gold lustre, and serves as a substitute for archil. It dissolves in hot water and
alcohol with a purple red color. It explodes at 215°. The other salts of isopur-
puric acid are obtained by double decomposition.

AMIDO-DERIVATIVES OF PHENOL. 679

The dinitrophenols yield similar derivatives with potassium cyanide.
_ Two isomeric Trinitrophenols (/?- and >■■) are obtained by nitrating the di-
nitrophenols prepared from meta-nitrophenffl and are very similar to picric acid.
jS-TrinitrophenolJ melts at 96°; y-trinitrophenol at 117° (Berichte, 16, 235).

Innumerable chlornitrophenols have been obtained by the action
of the halogens upon the nitrophenols, or by nitration of the halo-
gen derivatives.

AMIDO-DERIVATIVES OF PHENOL.

These, like the anilines, are obtained by the reduction of the
nitrophenols. In the case of the poly-nitrated phenols, ammonium
sulphide occasions but a partial, tin and hydrochloric acid, how-
ever, a complete reduction of the nitro-group (p. 592). Thus,
dinitrophenol, C6H8(N02)2.0H, yields nitro-amido-phenol, CeHs.
(N02)(NH)2.0H, and diamido-phenol, CeHjCNHOa-OH.

The amido-group considerably diminishes the acid character of
the phenols. This class of derivatives no longer forms salts with
alkalies, and only yields such compounds with the acids. Their
amido-hydrogen, like that of the anilines, is replaced by acid
radicals on heating with acid chlorides or anhydrides.

I. c-Amidophenol, CgH4(NHj).0H, is produced from orthonitrophenol by
reduction with tin and hydrochloric acid, and is precipitated from its HCl-salt by
alkaline carbonates in colorless leaflets, which rapidly turn brown. It is more easily
obtained by dissolving orthonitrophenol in alcoholic ammonia, and leading HjS into
the solution, when the phenol separates in crystalline form. It melts at 170° and
is slightly soluble in water (in 50 parts). When potassium cyanate acts upon
the hydrochloride of orthoamidophenol, it produces oxyphenyl urea, CgH^(OH)
NH.CO.NHj, melting at 154°. Potassium sulphocyanide forms»oxyphenyl thio
urea, CgH^(0H).NH.CS.NH2, melting at 161°. o-Amidophenol can form anhy
dro- or ethenyl-bases ; this it does by uniting its two side-chains to a carbon atom
These new derivatives contain both the benzene ring and that of oxazole (p. 555)
As they have two carbon atoms in common, they are called benzoxazoles : —

^6^4^ Tvr/CH, Benzoxazole.

The method pursued in producing this new class of compounds consists in heat-
ing o-amidophenols with acids or anhydrides. Acidyl derivatives are first formed,
but they part with water : —

Formyl Amido-phenol. Methenyl-amido-phenol.

In like manner ethenylamido-phenol is derived from acetyl amido-phenol.
Phosgene, COClj, gives rise to the oxy-methenyl derivative (see below).

68o ORGANIC CHEMISTRY.

The thiohydrides of the anhydro-bases are formed : —

(i) By heating o-amidophenols with carbon disulphide.

(2) From o-oxyazobenzene by a similar treatment ; as well as from the hydra-
zones ofortho-quinones (Berichte, 22, 3232, 3241).

The benzoxazoles are feeble bases. Their combinations with salts are unstable.
Boiling hydrochloric acid separates them into their components.

Methenyl Amidophenol, benzoxazole, is produced by boiling tf-amido-
phenol with formic acid. It consists of vitreous crystals, melting at 30.5°, and boil-
ing at 182°.

Oxymethenyl-amidophenol, or Carbonyl-Amidophenol, derived from the
preceding, possesses an atomic grouping analogous to that of the lactams or lac-
times (see these j : —

These two formulas are probably tautomeric. The above compound is formed
by allowing chlor-carbonic ester to act upon tf-amidophenol, and by heating oxy-
phenyl urea (see above). NPJg splits off. It sublimes in leaflets with mother-of-pearl
lustre ; these melt at 137° and yield an acetyl derivative, melting at 95° {Berichte,
16, 1829). It is most readily made by conducting COClj into the benzene solution
of o-amidophenol (^^nV;4/?, 20, 177). In most reactions it conducts itself as a
lactam (ibid.) ; it also unites, as a CO-compound, with phenylhydrazine [Berichte,
19, 2270).
Two different ethers are obtained by replacing its hydrogen by alkyls : —

^N^ /N(CjH5)

CeH^C ^CO.CjHj and C,H/ >C0.

Lactime Ether. Lactam Ether.

The lactime ether is produced by acting upon o-amidophenol hydrochloride with
imido-carbonic ester (Berichte, 19, 2655). It is an oil with peculiar odor, and
boils at 225-230°. When digested with concentrated hydrochloric acid, "it breaks
down into ethyl chloride and oxymethenyl-amido-phenol.

The lactam ether is formed when ethyl iodide and carbonyl-amidophenol interact
in alkaline solution (Berichte, 19, 2268; 20, 177). It melts at 29°, and when
heated with concentrated hydrochloric acid to 180°, it is resolved into carbon di-
oxide and ethyl-amido-phenol.

The sulphur compound, corresponding to oxymethenyl-amidophenol,

CeHs^o/C-SH or CeH^/^H^CS,

Thiohydryl-methenyl-amido- Thiocarbonyl-amido-

phenol, phenol.

is produced either by the action of carbon disulphide upon o-amidophenol, or of
potassium xanthate upon the hydrochloride; further, upon heating oxyphenyl
sulphurea (see above) (Berichte, 16, 1825; 20, 178). It melts at 193-196°, and
dissolves in alkalies and ammonia. When boiled with aniline it becomes Anilido-

carbamido-phenol, CgHj^^Q^C.NH.CgHj, melting at 173°. Amido-car-

bamido-phenol, CjH^^^q'^C.NHj, isomeric with phenylene urea (Berichte,

23, 1047), is formed on boiling oxyphenyl thiourea (p. 679) with mercuric
oxide. It crystallizes from water in large plates, melting at 130°. The ethe-

AMIDO-THIOPHENOL. 68 1

nyl compound is a liquid, and boils at 182°. Benzenyl-amido-phenol,

CgH^^' r\yC. CgHj, is produced by the reduction of benzoyl-ortho-nitrophenol,

and when ■ digested with hydrochloric acid yields Benzoyl-amido-phenol,
C6H4(OH).NH.CO.CgH5.

Methyl iodide (3 molecules) and potassium hydroxide change 0 amidophenol
"(analogous to the formation of betaine from glycocoU, p. 316) into Trimethyl

N(CH3)3
-ammonium-phenol, CgH^'^ | (Berichte, 13, 246), which crystallizes

from wajer in white prisms, containing i H^O. It tastes bitter, and dissolves easily
in water but not in ether. It breaks up by distillation into CH3CI and Dimethyl-
amido-phenol, C6H^(OH).N(CH3)j, which melts at 45°. Its HQ-salt,

^6^4\OH , gives the base again with silver oxide.

2. zre-Amidophenol, C5H4(NH2).OH (l, 3), is obtained by the reduction of
meta-nitrophenol with tin and hydrochloric acid. Technically, it is produced by
heating resorcin to 200° with hydrochloric acid and ammonia (Berichte, 22, Ref.
849). In this way the alkylamines yield the alkyl«-amido-phenols. The latter
can also be obtained from the dialkyl-aniline sulphonic acids (Berichte, 22, 622).
./^««-OT-amidophenol is not very stable. Nitric acid converts it into resorcin. '
Dimethyl vi-amidophenol melts at 87° ; diethyl-m-amidophenol boils at 280°.
wz-Amidophenol and its alkyl derivatives are employed in the preparation of
rhodamine dyes.

3. p-Amidophenol, C5H^(NH2).OH, is obtained by reducing /-nitrophenol
with tin and hydrochloric acid, and by distilling amidosalicylic acid. It sublimes
in shining leaflets, and melts at 184° with decomposition. It is oxidized to
quinone by chromic acid, or by PbOj and sulphuric acid. Bleaching lime con-
verts it, as well as its substitution products, into quinone chlorimides.

p-Amidophenetol, C^'R^iJ^'B.^.O.Q,^^, Phenetidine, is the ethyl ether. It

boils at 242°. Boiling glacial acetic acid converts it into CgH.^ - „'„ " ^'
phenacetin, which has been applied as an antipyretic.

Amido-thiophenol, C5H4(NH2)SH, (l, 2), is obtained from ortho-nitro-ben-
zene-sulphonic chloride, CgH4(N02).SOjCl, by reduction with tin and hydro-
chloric acid; also from acetanilide, C5H5.NH.CO.CH3, by heating with sulphur
and fusing with caustic alkali (Berichte, 13, 1226). A better method to pursue is
to fuse benzenyl-amidothiophenol with caustic potash (Berichte, 20, 2259). It
crystallizes in needles ; melting at 26°, and boiling at 234°.

i>-Amido-thiophenol (like o-amidophenol, p. 679) forms thieankydro-com^\m&%
by linking its two side-chains to a carbon atom. Because these derivatives con-
tain the t^iazolering they are called Benzothiazoles : —

CjH /?'^C.X, Benzothiazole.

They bear the same relation to quinoline that thiophene bears to benzene (they
contain an S-atom instead of the group HC : CH, hence they show similarity to
the quinoline compounds (Beri(hte, 21, 2629). They are formed:-^

57

682 ORGANIC CHEMISTRY.

(i) By the action of acid chlorides or anhydrides upon the o-amido-thiophenols
(p. 680) :—

C^H./^H, _^ CHO.OH = C,H^/^^CH + 2H,0.

Methenyl Amido-

thiophenol, Benzo>

thiazole.

If acetyl chloride be used the product will be ethenyl amido-lhiophenol or
benzo-methyl-thiazole.

(2) By oxidizing the thioanilides with alkaline potassium ferricyanide {Berichie,
ai, 2624; 22,905):—

C5H5.NH.CS.CH3 + O = CjH /^^CCHj + HjO.

Thioacetanilide. Ethenyl-amido-

thiophenol.

(3) By boiling the acid anilides with sulphur (in slight quantity) {^Berichie, 13,
1223; 22,905):—

C,H,.NH.C0.CeH5 + S = C,H,/f Jc.QH^ + H,0.
Benzanilide. Benzenyl-amido-thiophenol.

(4) The thiohydrides of the anhydrobases may be obtained from the o-amido-
thiophenols and CS2 (^Berichte, 20, 1790) ' —

Ce^^XOH + CS^ = C,H,/N)c.SH + SH,.

Thiomethenyl-amido-
thiophenol.

The benzo-thiazoles are liquids that boil without decomposition. They have an
odor like that of pyridine. Their salts are not very stable. Fused alkalies
decompose them into their components.

The Methenyl-amido-thiophenol, Z^H^'C g \CH, benzo-thiazole (isomeric

with phenyl mustard oil, C8H5.N:CS, and phenyl sulphocyanate, CgHj.S.CN), is
produced on heating amidothiophenol with formic acid. It is an oil smelling like
pyridine, and boiling at 230°.

Chlormethenyl-amido-thiophenol, chlorphenyl mustard-oil, C,HjNSCl,
results from phenyl mustard-oil on heating it to 160° with PCI5: —

CsH5.N:CS 4- CIj = CgH /^■^CCl + HCl.

It melts at 24°, and boils at 248°. It reverts to methenyl amidothiophenol by the
action of tin and hydrochloric acid. The chlorine atom in it is readily adapted to
double decompositions. The hydroxide, CsHj(SN)C.OH, oxy-phenyl mustard-
oil, melts at 136°, and dissolves readily in alkalies. Sodium ethylate converts the
chloride into the ethyl oxide (ethyl oxyphenyl mustard-oil), C5H^.(SN).C.O.
C2H5. This results from the oxidation of phenyl-sulphurethane with potassium
ferricyanide (see above). It melts at 25°, and when boiled with hydrochloric acid
yields the hydroxide.
The amide melts at 129°. The thiohydride, C8H^(NS)C(SH), results

TRIAMIDOPHENOL. 683

when the chloride is acted upon with alcoholic sodium sulphydrate and from
«-amidophenol and CSj. It melts at 179° (Berichte, ao, 1790).

Ethenyl-amido-thiopheno], CgH^<'^5,^C.CH3, is obtained by boiling

o-amido-thiophenol with acetic anhydride, and by .oxidizing thioacetanilide (see
above). It is a liquid, boiling at 238°.

Benzenyl-amido-thiophenol, CjH^;^^ ^C.CgH., results upon heating

\^ ' . .
phenylbenzainide with sulphur, and also in the oxidation of thiobenzanilide with

potassium ferricyanide (see above and Berichte, 19, 1068). It crystallizes in long
needles, melting at 1 14°.

Dinitro-amido-phenol, C5H2(NHj).(N02)2.0H, picramic acid, is obtained by
reducing ammonium picrate in alcoholic solution with hydrogen sulphide. It
forms red needles, which melt at 165°. It yields red-colored crystalline salts with
bases.

Triamidophenol, C5H2(NHj)3.0H, is obtained from picric acid by the
action of phosphorus iodide, or by tin and hydrochloric acid (Berichte, 16, 2400).
When set free from its salts it decomposes very quickly. Its salts, with 3 equiva-
lents of acids, crystallire well. The Hl-salt, C8H30(NH2)3.3HI, crystallizes
in colorless needles. These salts color water which is faintly alkaline, and even
spring water, a beautiful blue. , If ferric chloride be added to the solution of
the hydrochloride, it will become deep blue in color, and brown-blue needles
with metallic lustre will separate ; they are HCl-amido-di-imido-phenol, C5H2(OH)

(NHj)^.!^., J>, which dissolves in water with a beautiful blue color.

Diazo-compounds of the Phenols, such as phenol diazochloride, ^^^iCryn

result from the action of nitrous acid upon the amido-phenols ; free diazo-com-
pounds have been obtained from the substituted amido-phenols, e.g. : —

CeH^Cl, { ^^\, CeH3(N0,) { ^»\ C,H,(NO,), { ^^X

in which the second affinity of the diazo-group appears to be joined to oxygen
(p. 630).

Analogous sulphur-compounds, the diazo-sulphides, are formed when nitrous
acid acts upon the o-amidothiophenols and their anhydro-compounds (Berichte,
22, 905) : —

CeH^/NH, ^ jjQ^jj ^ C,-a.^(^'y^ + 2H,0.

They are very stable and crystallize well. They distil without decomposition
under reduced pressure.

o-Phenylene-diazosulphide, CgH^^o ^N, is easily produced when nitrous acid

acts upon benzenyl-amidothiophenol. It forms large plates, having a pleasant
odor. It melts at 37°, and volatilizes with steam.

The azo-derivaiives of the phenols are produced by reduction of the nitro-
phenols in alcoholic potassium hydroxide- solution (p. 641) ; further, by the action

684 ORGANIC CHEMISTRY.

of the anilines upon the nitrosophenols. They are perfectly analogous to the azo-
derivatives of the benzenes (Berichte, 17, 272).

Amidothiophenyls or Thioanilines.

These compounds result when nitrothiophenyls are reduced. The diamido-
phenyl sulphides are also produced from anilines by boiling the latter with
sulphur : —

2C,H,.NH, + S, = S(^«j^;^g^ + SH,.

The alkyl anilines and sulphur yield derivatives resembling the thiazoles [Berichte,
22, 67). Sulphur chloride, or thionyl chloride, SOClj {Berichte, 21, 2056; 23,
552), converts the dialkylanilines into alkylic-thio-anilines. The mono-alkyl-
anilines, by like treatment, yield Thionyl anilines, e. g.,%0 (CgH^.NH.CHjjj
{Berichte, 23, 3020). Silver nitrate and ammonia desulphurize the dialkyl-com.
pounds, with the formation of oxydimethylauilines, e. g., 0[CgH4.N(CHg)2]3
{Berichte, 21, 2056).

Diamidophenyl Sulphide, S(' p*jj*'nH^' '^^^"""'^^'^^t results from the reduc-
tion of dinitrophenyl-sulphide (p. 672), and by heating aniline and sulphur to 150-
160°, then adding litharge {Berichte, 4, 384). It crystallizes from hot water in
long needles, melting at 105°.

Thio p-toluidine, ^C r^ vs 1 r\^ \ ■fz\^^ ' Diamidotolyl Sulphide, is obtained by

heating ^-toluidine with sulphur and litharge to 140°. Tt crystallizes in large
leaflets, melting at 103°. The sodium salts of thio- and dithiotoluidine sulphonic
acids dye unmordanted cotton {Berichte, 21, Ref. 877).

The bi-diazo salts of thio-toluidine combine with naphthylamine-sulphonic acids
and yield disazo dyes of a brown-red color {Berichte, 20, 664).

Dehydrothio toluidine, C,4Hj2N2S, is formed when thio-/-toluidine and sul-
phur are heated to 185° {Berichte, 22, 423, 581, 970). It crystallizes from alcohol
in yellow needles, melting at 191°. Its alcoholic solution shows a beautiful blue
fluorescence. Another base, very similar to the preceding, is formed at the same
time it is produced. The sodium sulphonate of the latter is primuline, which
dyes unmordanted cotton yellow if it be diazotized upon the fibre. It can also
combine with phenols and anilines.

Benzenyl-p-mamido-thiocresol,Cll^.C^'li^<^^^S.CgH^, results when the

amido-group is eliminated from dehydro-thio-toluidine. It may be synthetically
prepared by oxidizing thio-benz-toluidine, CH3.CeH4.NH.CS.CjH5 (p. 682)
{Berichte, 22, 1063).

PHENOL-SULPHONIC ACIDS.

Ortho- and Para-phenolsulphonic Acid, C5H4(OH).S03H,
are formed when phenol dissolves in concentrated sulphuric acid ;
at medium temperatures the former is the more abundant, but
readily passes into the para- on the application of heat.

Preparation. — To obtain the acids, the solution of phenol in sulphuric acid
(equal parts) is diluted with water and saturated with calcium carbonate. The
nitrate from the gypsum, containing the calcium salts, is boiled with potassium
carbonate, thus producing potassium salts. On allowing it to crystallize the potas-

HOMOLOGOUS PHENOLS. 685

sium salt, CgH^(0H).S03K, of the para-z.c\A. first separates in hexagonal plates;
later the ortho-salt, CgH^(0H).S03K + aHjO, crystallizes out in prisms, which
soon effloresce on exposure {Annalen, 205, 64).

The free acids can be obtained in crystalline form by the slow evaporation of
their aqueous solution. When the aqueous ortho-acid is boiled it changes to para.
The aqueous solution of the orlho-acid is applied as an antiseptic under the name
of aseptol {^Berichte, 18, Ref. 506). The para-acid yields quinone if its sodium
salts be oxidized with Mn02 and sulphuric acid. PCI5 converts it into (l, 4)-
chlor-phenol and (l, 4)-dichlorbenzene. When the ortho-acid is fused with KOH
at 310° it yields pyro-catechin— hence it belongs to the ortho-series; the para-
acid does not react at 320°, and at higher temperatures yields diphenols.

The iodaticn of the para-acid produces Di-iodo-phenol sulphonic Acid, CjH^
l2.(OH).S03H. This is applied as an antiseptic, bearing the name Sozo-iodol
(Berichte, 21, Ref 250).

Meta-phenolsulphonic Acid (l, 3) is produced when meta-benzene-disul-
phonic acid (p. 663) is heated to 170-180° with aqueous potassium hydroxide
(Berichte, 9, 969). The potassium salt, C8H^(OH).S03K -)- HjO, effloresces
in the air ; the free acid consists of delicate needles, and contains 2 molecules of
HjO. Fusion with potassium hydroxide at 250° converts it into resorcinol (l, 3).
When para-benzene-disulphonic acid is heated with caustic alkali, meta-phenol-
sulphonic acid is also produced at first, but it yields resorcinol later.

Phenol-disulphonic Acid, CgHg(OH).(S03H)2, results from the action of
an excess of sulphuric acid upon phenol, also upon (l, 2-)- and (l, 4)-phenol-
sulphonic acid, hence its structure is (i, 2, 4 — OH in l). It is further produced
in the action of SO^Hj upon diazobenzene sulphate. The solutions of the acid
and its salts are colored a dark red by ferric chloride.

Phenol-trisulphonic Acid, C8H2(OH).{S02H)3 (i, 3, 5, OH), is obtained
when concentrated sulphuric acid and PjOj act upon phenol. It crystallizes in
thick prisms with 3^H20.

HOMOLOGOUS PHENOLS.

I. Cresols, QH^;' QTT^ Oxy-toluenes.

The cresol contained in coal-tar appears to contain three isotner-
ides, but they cannot be separated. They are obtained pure from
the am ido- toluenes (toluidines) by replacing the amido-group by
hydroxyl, and from the toluene-sulphonic acids by fusion with
potassium hydroxide. The cresols axt changed to toluene when
heated with zinc dust. Sodium and carbon dioxide produce the
corresponding cresotinic acids, C6H3(CH3)(OH).C02H.

Ortho-cresol (i, 2), from orthotoluidine and ortho-toluene-sulphonic acid,
melts at 31°, and boils at 188°. It is obtained from carvacrol (p. 688) when
heated with P2O5. It yields salicylic acid (i, 2) on fusion with potassium
hydroxide; FCjClg colors it blue. For its nitro-derivatives, see Berichte, 15,
i860, and 17, 270.

Nitroso-o-cresol, from p-cresol by means of nitrous acid and from toluquinone
and hydroxylamine (p. 676), melts at 134°. Consult Berichte, 17, 351, for azo-
and diazo-compotmdsof the cresols.

686 ORGANIC CHEMISTRY.

Meta-cresol {\, 3) is formed from thymol (p. 688), when digested with phos-
phoric anhydride : —

CioHiP = CjHj.OH + QH,,

also from m-toluidine (from m-nitrobenzaldehyde).

Meta-cresol is a thick liquid, which solidifies when exposed to cold, melts at
4-5° (Berickie, 18, 3443), and boils at 201°. Its benzoyl derivative, C,H,0.
CjHjO, melts at 38°, and boils at 300°. The methyl ether is an oil boiling at 176° ;
it is oxidized by potassium permanganate to methyl-meta-oxybenzoic acid. Meta-
cresol yields meta-oxy-benzoic acid on fusion with caustic potash. The nitration
of meta-cresol forms a trinitro-cresol, while the ortho- and para-derivatives only
yield dinitro-derivatives (Berichte, 15, 1864).

Trinitro-m-cresol, C ^Vi^f^O^ ^^/^^ , melts at 106°; it is also obtained from

nitrococcic acid. Consult Berichte, 15, 1130 and 1864, upon nitrometa-cresols.

Para-cresol (l, 4), from solid paratoluidine, and from para-toluenesulphonic
acid, forms colorless needles, melting at 36°, and boiling at 198°. Its odor
resembles that of phenol ; it dissolves with difficulty in water. Ferric chloride
imparts a blue color to the aqueous solution. It yields paraoxybenzoic acid when
fused with caustic potash. The benzoyl compound, C,H,0.CjH50, crystallizes
in six-sided plates, and melts at 70°. The ethyl ether, C^HjO.C^Hj, is an
aromatic-smelling liquid, which boils at 188°. The methyl ether boils at 174°.
Chromic acid oxidizes it to anisic acid, CgH4(O.CH3).C02H.

Consult Berichte, 21, 729, upon Nitrosocresols.

The nitration of para-cresol produces different nitro-cresols. Dinitro-cresol,
C,H5(NOj)jOH ( I, 4, 2, 6), is also obtained by the action of nitrous acid upon
paratoluidine {Berichte, 15, 1859), and as potassium or ammonium salt represents
commercial Victoria orange or Gold-yellorv. It consists of yellow crystals, melt-
ing at 84°, and is not as soluble in water as picric acid. Mixed with indigo-
carmine it forms emerald green (for liqueurs), and with aniline a carmine surrogate.
Commercial Saffran-surrogate is a mixture of the potassium salts of dinitro- para-
and ortho-cresols.

/-Amido-OT-thiocresol, C8H3(CH3)'^j^ji?' y is produced together with p-

amido-benzoic acid by the decomposition of dehydrothiotoluidine upon fusing it
with alkalies. Nitrous acid converts it into a diazo-sulphide (p. 683) {Berichte,
22, 1064).

Thio-cresols, C8H^(^(,tt^, Toluene sulphydrates, are obtained by the reduc-
tion of the chlorides of the three toluene sulphonic acids with zinc and hydro-
chloric acid (p. 672). (i, 2)-Thiocresol melts at 15°, and boils at 188°. (l, 3)-
Thiocresol is a liquid, and does not solidify at — 10°. (l, 4)-Thiocresol crystallizes
in large leaflets, melts at 43°, and boils at 188°.

It is singular that the cresols, and all other higher phenols, can-
not be oxidized with a chromic acid mixture ; the OH-group pre-
vents the oxidation of the alkyl group. If, however, the phenol
hydrogen be replaced by alkyls or even acid groups (in the phenol
ethers and esters), the alkyl is oxidized and oxyacids (their ether
acids) are produced : —

H /O-CH, /O.CH,

METHYL-PROPYL PHENOLS. 687

To oxidize the homologous phenols it is advisable to employ their
sulphuric and phosphoric acid esters — these are easily prepared —
and subject them to the action of an alkaline permanganate solution
{Berichte, 19, 3304). This oxidizing agent destroys the free phe-
nols completely.

The oxidation of the alkyls in the sulphonic acids of the homologous benzenes
is dependent upon the position of the sulpho-group. In general, negative atoms,
or atomic groups, prevent the oxidation of the alkyls in the ortho-position by acid
oxidizing agents (pp. 584 and 591), whereas alkaline oxidizers (like Mn04K)
do the reverse, that is, first oxidize the alkyl occupying the ortho-position (An-
nalen, 220, 16).

Consult Berichte, 14, 687, on the deportment of cresols in the animal organism.

2. Phenols, CgHg.OH.

The six possible xylenols, C8H3(CH3)2.0H, have been prepared partly from
the corresponding xylidines, and partly by fusing isomeric xylene-sulphonic acids
with potassium hydroxide. Further fusion oxidizes them to oxytoluic and oxy-
phthalic acids.

Ethyl Phenols, CeH4(C2H5).OH. The three isomerides have been prepared
from the corresponding ethyl-benzene-sulphonic acids when the latter were fused
with alkalies. The or/Ao-compound is a liquid, boiling at 209-210°. The meta
^boils at 202-204°. 'Y\\s.para is a solid, melts at 46°, and boils at 214° {Berichte,
22, 2672).

3. Phenols, CgHn.OH.

iJ/m/y/i)/, CjH2(CH3)3.0H, from amido-mesitylene, mesitylene sulphonic acid
and pseudocumidine, is crystalline, melts at 68-69°, and boils at 220°. Isomeric
Fseudocumenol, C8H2(CH3)3.0H, from pseudo-cumene-sulphonic acid, consists
of delicate needles, melting at 73°, and boiling at 232° (Berichte, 17, 2976).

p-Propyl Phenol, CjHj(0H).C3H,, from propyl benzenesulphonic acid, boils
at 232°. /-Isopropyl-benzene, 65114(6311,) .OH, from isopropyl-benzenesulphonic
acid, melts at 61°, and boils at 229°.

4. Phenols, C10H13.OH.

Tetramethyl Phenol, CgH(CH3)4.0H (l, 2, 4, J, 6 — OH in 6), durenol, from
durene sulphonic acid, melts at 117°, and boils at 250° (Berichte, 18, 2843).

Methyl-propyl Phenols. — There are twenty possible isomerides.
Thymol and Carvacrol merit notice. They occur in vegetable oils : —

/CH3 (I) /CH, (I)

C3H3fC3H,(4) and CeHj-QH, 4 .
\0H (3) \OH (2)

Both are derivatives of ordinary para-cymene (p. 577), and contain
the normal propyl group (^Berichte, 19, 245). In thymol the OH-
group is in the meta-position with reference to the methyl group ;
in carvacrol, however, in the ortho-position. Both decompose into
propylene and cresols when heated with P2O5: —

CeH3(^fl|,)-0H =C,H,/gg3 + C3H,,
thymol yielding meta-cresol and carvacrol para-cresol.

688 ORGANIC CHEMISTRY.

Thymol exists with cymene, CioHu, and thymene, CioHie, in oil
of thyme (from Thymus vulgaris), and in the oils of Pty.chotis
ajowan and Monarda punctata. To obtain the thymol shake these
oils with potassium hydroxide, and from the filtered solution pre-
cipitate thymol with hydrochloric acid. It is artificially prepared
from nitrocuminaldehyde, C6Hs(N02).(C3H,).CHO, by its conver-
sion into the dichloride, reduction of the latter to cymidine, C^Hs.
(NH2)(C3H,).CH3, by means of zinc and hydrochloric acid,
and decomposition of the diazo-compound of the latter with water
{Berichte, 19, 245). Thymol crystallizes in large colorless plates,
melting at 44° and boils at 230°. It has a thyme-like odor and
answers as an antiseptic. Ordinary cymene is obtained by distilling
it with P2S5.

Iodine and caustic potash convert thymol into iodothymol. This has been sub-
stituted for iodoform under the name of annidalin.

Nitrous acid changes thymol to nitroso-thymol, Cj (,Hj 2 (NO)OH, melting at
160°. The same compound results on treating thymoquinone with hydroxylamine
(p. 67s and Berichte, 17, 2061).

Carvacrol, CjjHjj.OH, Oxycymene, occurs already formed in the oil of cer-
tain varieties of satureja ; it is produced on heating isomeric carvol, Cj qH j ^O, with
glacial phosphoric acid (^Berichte, 20, 12). It is ariificially prepared from cymene-
sulphonic acid by fusion with KOH, and by heating camphor with iodine (^ part)
or ZnClj. It is a thick oil, solidifying at low temperatures ; it melts at 0°, and
boils at 236°. Distilled with PjSj, it yields cymene and ihiocymene, CijHjj.SH,
which boils at 235°.

Carvol, CijHj^O (see above), isomeric with carvacrol, is contained in oil of
cumin. It is an oil boiling at 225°. When heated with potassium hydroxide or
phosphoric acid it changes to the isomeric oxycymene. In its behavior it is very
much like camphor, Ci„H] jO (see this); it contains a CO-group, inasmuch as it
combines with hydroxylamine and phenylhydrazine (Berichte, 17, 1578). Car-
voxime, Cj|,Hj4:N.OH, melts at 71° and is identical with nitrosohesperidine
(Berichte, i8, 222o). According to its constitution carvol (like camphor) is a
keto-derivative of a. dihydrobenzene, and indeed of dihydrocymene. When it is
converted into oxycymene there occurs a transposition of the reduced benzene
nucleus into the normal, of the secondary ketone-form into the tertiary phenol-
form (Berichte, 20, 491 ; 21, 473) (compare phloroglucin) : —

C3H,.c(^g^-^~^CH.CH3 yields CjHj.C^^g " gg^C.CH,.

Carvol. Oxy-cymene.

Isobutyl Phenol, C8H^(C4Hj).OH, is readily obtained by heating phenol with
isobutyl alcohol in the presence of ZnCl, (p. 667). It has also been prepared
from isobutyl-auiline, by means of the diazo-compound. It melts at 99°, and
boils at 238°.

Pentamethyl Phenol, Cg(CHg)5.0H = CnHijO, is obtained from amido-
pentamethyl benzene (^Berichte, 18, 1827). It melts at 125°, and boils at 267.°.

PYROCATECHIN. 689

DIHYDRIC PHENOLS.

( /"iTT ( Pyrocatcchin,
" * \ OH (.Hydroquinone.
CeHj^CHj) I Qjj I Homo'-pyrocatechin.

n xj (CTf ^ rOH fBeta-orcin.
>-6"^2(,*-"3j2'^OH IHydrophloron.

These are obtained like the monohydric phenols, by fusing mono-
halogen phenols, CsHiX.OH, halogen benzenesulphonic acids and
phenolsulphonic acids with potassium hydroxide (p. 666). It must,
however, be observed that often the corresponding dioxy-benzenes
do not result, but in their stead (especially at higher temperatures)
the more stable resorcinol (i, 3). They are also produced by diazo-
tizing the amidophenols, and by the dry distillation of aromatic
dioxyacids with lime or baryta.

The dioxybenzenes belonging to the para-series, are capable of
forming quinones, CsH^Oj, when oxidized.

Dioxybenzenes : —

(i) Pyrocatcchin, C6H<(OH)2 (i, 2), Oxyphenic Acid, Cate-
chol, was first obtained in the distillation of catechine (the juice of
Mimosa catechu). It is formed by the dry distillation of proto-
catechuic acid, C6H3(OH)2.C02H, of catechuic and Moringa
tannic acids, and from (i, 2)-chlor- and iodo-phenols, or (i, 2)-
phenolsulphonic acid and many resins on fusion with potassium
hydroxide.

It is best prepared by heating guaiacol (from that portion of beech-wood tar
boiling at 195-205°) to 200° with hydriodic acid: —

CeH^/g^"' + HI = C,H,/Og + CH3I.

Or, ortho-phenolsulphonic acid may be fused with caustic alkalies (8 parts) to
330-360° (Journ. pract. Chem., 20, 308).

Pyrocatcchin crystallizes from its solutions in short, rhombic
prisms, and sublimes in shining leaflets. It is soluble in water,
alcohol and ether. It melts at 104°, and boils at 245°. On expo-
sure to the air its alkaline solutions assume a green, then brown and
finally a black color. Lead acetate throws out a white precipitate,
PbCeHiOj, from its aqueous solution ; while lime water imparts a
green color to it if concentrated. Ferric chloride colors its solu-
tion dark green, this changes to violet after the addition of a little
58

690 ORGANIC CHEMISTRY.

ammonia, sodium carbonate or tartaric acid. Ferric chloride im-
parts a green color to all ortho-dioxy-derivatives in solution, even if
one hydrogen atom is replaced by an alkyl. Pyrocatechin reduces
cold silver solutions and alkaline copper solutions. The application
of heat is required in the latter case.

Acetyl chloride produces the acetyl derivative, C6H^(O.CjH30)2, crystallizing
in needles.

Q^ ', Guaiacol, occurs in wood-tar and is

produced on heating pyrocatechin with potassium hydroxide and potassium methyl
sulphate to 180°. It is a colorless liquid, which boils at 200° and has a specific
gravity 1. 1 17. It dissolves with difficulty in water, readily in alcohol, ether and
acetic acid. Ferric chloride gives its alcoholic solution an emerald green color.
It forms crystalline salts with the alkali and alkaline earth metals. Its alkaline
solutions reduce gold, silver and copper salts. Guaiacol decomposes into pyro-
catechin and CH3I (also CH3.OH) when heated with hydriodic acid or fused with
KOH.

The dimethyl ether, Z^Yi^ifi.Ci^^^, is prepared by treating the potassium salt
of the mono-methyl ether with CH3I, and by distilling dimethyl-protocatechuic
acid with hme. It is a liquid, which boils at 205°. It is identical with veratrol,
obtained from veratric acid.

The carbonic ester, CjHj<^^^CO, results from the action of chlorcarbonic ester

upon pyrocatechin, and melts at 118°. Pyrogallol reacts similarly [Berichte, 13,
697), while, on the other hand, the mixed carbonic acid esters, e.^., CgH4(0.
002.02115)2 {Berichte, 19,2265), are formed in the action of chlorcarbonic esters
upon hydroquinone and resorcinol (as well as upon monohydric phenols).

(2) Resorcin, Resorcinol, C6H4(OH)2 (i, 3), is produced from
different resins (like galbanum and asafastidd) and from umbelliferon
on fusion with caustic potash. It results in the same way from (i,
3)-chlor-and iodophenol, from metaphenol sulphonic acid and meta-
benzene disulphonic acid, and also from various other benzene di-
derivatives not included in the meta-series, e.g., from the three
brom-benzene sulphonic acids (p. 663) and from both benzene di-
sulphonic acids (compare p. 689).

It was formerly obtained by distilling the extract of Brazil wood ; at present,
however, it is prepared technically from crude benzene disulphonic acid {Journ.
pract.Chem., 20, 319), and serves for the synthesis of different dyes. It is purified
by sublimation and by crystallization from benzene.

Resorcin crystallizes in rhombic prisms or plates, melts at 118°
when perfectly pure (otherwise at 102-110°), and boils at 276°. It
dissolves readily in water, alcohol and ether, but not in chloroform
and carbon disulphide. Lead acetate does not precipitate the
aqueous solution (distinction from pyrocatechin). Silver nitrate is
only reduced by it upon boiling ; and in the cold if ammonia be
present. Ferric chloride colors the aqueous solution a dark violet.

HYDROQUINONE. 69 1

Bromine water precipitates tribromresorcin, C8HBr3(OH)2, from the
solution. This crystallizes from hot water in needles. By heating
resorcinol with phthalic anhydride we get fluorescein ; the homolo-
gous metadioxybenzenes also yield fluoresceins. With diazo-com-
pounds it forms azo-coloring substances (p. 643).

The diacetyl compound, Q.^^[fi.C^fi\, is a liquid. The diethyl ether,
CgH^(O.C2H5)j, obtained by heating resorcinol with ethyl iodide and potassium
hydroxide, boils at 243°, the dimethyl ether at 214°.

Nitrous acid, acting upon a diluted resorcinol solution {Berichte, 8, 633),
produces dinitroso-resorcinol, CsHj(OH)j(NO)j or CaHj{0)j(N.OH)j (i, 3-
2,4) ('g.(>T^),{Berichte, 21, 1545; 23, 3193). This crystallizes with 2H2O in
yellow brown leaflets, which detonate on heating to 115° C. {^Berichte, 20, 1607).
It occurs in commerce under the names solid green, fast green.

Nitric acid vapors oxidize resorcinol to dinitroresorcin, C5H2(N02)2(OH)j,
melting at 142°. It yields dinitro-diamidobenzene when heated with ammonia.
Isodinitro-resorcin, obtained by nitration, mells at 212°. It pisses, by reduction,
into diamidoresorcin, C^^i^Yi^^.CiiVi.^)^ (i, 3-4, 6). The latter can also be
easily obtained by reducing resorcin-diazobenzene with tin and hydrochloric acid
(Berichte, 17, 881). When its ammoniacal solution is exposed to the air it oxidizes
to Diamido-resorcinol, CjH2(OH)2(NH2)j, separating in steel blue needles
{^Berichte, 22, 1653). It is soluble in caustic potash, and on application of heat
yields dioxyquinone (p. 702).

When cold nitric acid acts on resorcinol and various gum-resins (galbanum,
gum-ammoniac), or by nitrating metanitrophenol, we get Trinitro-resorcinol,
C5H(N02)3(OH)2 (Styphnic Acid, Oxypicric Acid) {Berichte, 21, 3119), which
crystallizes in yellow hexagonal prisms or plates. It melts at 175°, and sublimes
when carefully heated, but explodes on rapid heating. It dissolves easily in
alcohol and ether, but with difficulty in water. Ferrous sulphate and lime water
at first color it green, but this disappears (picric acid colors it blood-red). Trinitro-
resorcinol is a strong dibasic acid, yielding well crystallized acid and neutral
salts. The diethyl ester is solid, and melts at 120°-

If resorcinol be heated with sodium nitrite it forms a deep-blue dye, soluble in
water. Acids turn this red {Berichte, 17, 2617). It is used as an indicator under
the name of lacmoid {Berichte, 18, Ref. 126). Nitric acid, containing nitrous
acid, converts resorcin into two dyes: diazoresorcin and diazoresorufin (Weselsky).
These have also been called resorufin or resorutamin, CjjHjNOj, and resazurin,

CjjHjNO^. They appear to be derivatives of, phenoxazine, C^Hji^ j^^C^H^
(Nietzki, Berichte, 22, 3020; 23, 718). ^ ■^

3. Hydroquinone, C6H4(OH)2 (i, 4), was first obtained by the
dry distillation of quinic acid and by digesting its aqueous solution
with PbOj :—

CjHj.Oe + O = CeH^O, + CO, + 3H,0.

It results also on boiling the glucoside arbutin with dilute sulphuric
acid, or by the action of emulsin : —

CijHjeO, + H^O = C„H,02 + C.Hi^O^.
Arbutin. Hydroquinone. Glucose.

It is synthetically prepared by fusing (i, 4)-iodophenoI with potas-
sium hydroxide at 180°; or from oxysalicylic acid, and from para-

692 ORGANIC CHEMISTRY.

amidophenol. Worthy of note is the formation of various hydro-
quinone derivatives from succino-succinic ester (p. 566), or that of
hydroquinone in the distillation of succinates. The most convenient
method of preparing, it consists in reducing quinone with sulphurous
acid : CeH^Oj -f Hj = QHeOj.

Preparation,— r'Xo get hydroquinone, oxidize aniline in sulphuric acid (l part
aniline, 8 parts SO4H2 and 25 parts HjO) with pulverized CrjOjNaj (2^ parts)
until the dark precipitate, which first forms, has dissolved to a cloudy, brown
liquid (containing quinone and quinhydrone). Then conduct sulphurous acid
through the solution until the redaction is complete ; filter, extract the hydroqui-
none by shaking with ether, then purify the product by recrystallization from hot
water that has passed through animal charcoal (Berichte, ig, 1467), and contains
sulphur dioxide.

Hydroquinone is dimorphous, crystallizes in monoclinic. leaflets and hexagonal
prisms, which melt at 169°, and sublime in shining leaflets ; it decomposes when
quickly heated. It dissolves readily in water (in 17 parts at 15°), alcohol and
ethe* It forms crystalline compounds with HjS and SO^ ; these are decomposed
by water. Ammonia colors the aqueous solution reddish -brown. It is only in
the presence of ammonia that lead acetate produces a precipitate in the solution
of hydroquinone. Oxidizing agents (like ferric chloride) convert hydroquinone
into quinone ; quinhydrone is an intermediate product.

Hydroxylamine and hydroquinone form quino-dioxime, by the absorption of
two hydrogen atoms [Berichte, 22, 1283).

Methylhydroquinone, CjH^(' „„ ^, is formed along with hydroquinone in

the decomposition of arbutin with acids or emulsin ; and from hydroquinone by
heating it with caustic potash, and methyl iodide or potassium methyl sulphate
[Berichte, 14, 1989). It crystallizes from hot water in hexagonal plates, melts at
53°, and boils at 243°. The dimethyl ether, C^Yi^{O.Q.Yi.^] ,i^,raA\s aX. 56°, and
boils at 205°. The diethyl ether melts at 66°, and boils at 247°.

We obtain the hydroquinone halogen substitution products by direct substitution,
or from the substituted quinones and arbutins ; and by the addition of HCl or HBr
to quinone: CjH^Oj -f- HCl = CgH3Cl(0H)j (Annalen, 201, 105, and 210,
133). Two dinitro products are obtained by the nitration of diethylhydroquinone.
They can be reduced to two diamidohydroquinones, Cg H ^ (NH j ) ^ (OH) ^ {Berichte,
23, 1211).

When chloranil (tetrachlorquinone) is digested with a diluted solution of primary
sodium sulphite, we get at first tetrachlor-hydroquinone, but later two Cl-atoms
are replaced by sulpho-groups. The aqueous solution of the resulting dichlor-

hydroquinone disulphonic acid, CgCl^ | /gO H^ ' '^ '=°^°"'S"1 indigo-blue by ferric

chloride. When its alkaline solution is exposed it oxidizes to potassium euthio-

chronaie, Q,^{(iYi),^i. lA^v^ • This is a quinone-like compound.

(2) Dioxytoluenes, C6H3(CH3)(OH),. Four of the six pos-
sible isomerides are known. For their reactions see Berichte, 15,

2995-

I. Orcin, Orcinol, C6H3(CH3)(OH)2 (i, 3, 5), is found in
many lichens of the variety Roccella and Leconora, partly free and

ISO-ORCIN. 693

partly as orsellic acid or erythrine, and is obtained from these acids
either by dry distillation or by boiling with lime : —

C,H (OH),.CO,H = C,H,(OH)2 + CO,;

Orsellic Acid. Orcinol.

It is obtained by fusing the extract of aloes with caustic potash. It can be pre-
pared synthetically from dinitro-paratoluidine and various other toluene derivatives
by the alteration of their side groups {Berickte, 15, 2992). It crystallizes in color-
less, six-sided prisms, containing one molecule of water. It dissolves easily in
water, alcohol and ether, and has a sweet taste. It melts at 56°, when it contains
water, but gradually loses this, and melts (dried in the dessicator) at 107°. It
boils at 290°. Lead acetate precipitates its aqueous solution ; ferric chloride
colors it a blue violet. Bleaching lime causes o. rapidly disappearing dark violet
coloration. It yields azo-coloring substances with diazo-compounds, and there-
fore has the 20Hgroups in the meta-position (p. 643). It does not form a
fluorescein with phthalic anhydride (p. 691).

The orcinol hydroxyl-groups can be replaced by acid and alcohol radicals.
The dimethyl ether, C,Hj(0.CH3)j, is a liquid, boils at 244°, and when oxidized
with MnOjK yields the dimethyl ether of symmetrical dioxybenzoic acid^ See
Berichte, 20, 1608, for dinitroso-orcin.

On allowing its ammoniacal solution to stand exposed to the air
orcinol changes to orcein, QeHaiNaO, {^Berichte, 23, Ref. 647),
which separates out in the form of a reddish-brown amorphous
powder. Orcein forms red lac-dyes with metallic oxides. It is the
chief constitutent of the coloring matter archil, which originates
from the same lichens as orcinol through the action of ammonia
and air. Litmus is produced from the lichens Roccella and
Leconora, by the action of ammonia and potassium carbonate.
The concentrated blue solution of the potassium salt, when mixed
with chalk or gypsum, constitutes the commercial litmus.

2. Iso-qrcin, C5H3(CH3).(OH)j (l, 2,4 — CH3 in i) (Cresorcin, y-orcin), is
obtained by fusing a-toluene disulphonic acid with KOH ; also from nitro-para-
toluidine, a-toluylene diamine and amido-o-cresol {Berichte, 19, 136). It forms
soluble needles, melting at 104°, and boiling at 270°. It gives a violet coloration
with ferric chloride, and forms a fluorescein with phthalic anhydride.

3. Homopyrocatechin, C5H3(CH3)(OH)2 (i> 3, 4 — CH3 in i), is formed
from its methyl ether, creosol, when heated with hydriodic acid, and by the distil-
lation of homoprotocatechuic acid. It has been synthetically prepared from meta-
nitro-para-toluidine {Berichte, 15, 2983). It is a non-crystallizable syrup; other-
wise it is like pyrocatechin. It reduces Fehling's solution and a silver solution,
even in the cold, and is colored green by ferric chloride. ,q (-,„ / \

Its monomethyl ether is the so-called Creosol, CgH3(CH3)^Q^ 'W;, formed
from guaiacum resin and is found in beech-wood tar. ^ ^^'

That fraction of the beech-wood tar (creasote p. 667), boiling at 220°, consists
chiefly of creosol and phlorol. Potassium-creosol is precipitated on adding alco-
holic potash to the ethereal solution ; potassium phlorol remains dissolved (Berichte,
10, 57; 14,2010).

Creosol boils at 220°, and is very similar to guaiacol (p. 690). It
reduces silver nitrate on warming, and in alcoholic solution is
colored a dark green by ferric chloride.

694 ORGANIC CHEMISTRY.

It yields an acetate with acetic acid. Vanillinic acid may be obtained from the
acetate by oxidizing the latter with potassium permanganate, and saponifying with
caustic potash. Its methyl ether, C5H3(CH3)(O.CH3)j (methyl creosol, dimethyl-
homo-pyrocatechin), boils at 214-218°, and when oxidized with potassium per-
manganate yields dimethyl-protocatechuic acid. The relations of these substances
are seen in the following formulas (see Vanillin) : —

fCH, (I) (CO^H fCO^H

C^H^ O.CH3(3) CeH, \ O.CH, C^H, \ OH
(OH (4) (oh (oh

Creosol. Vanillinic Acid. Frotocatechuic Acid.

4. Toluhydroquinone, C5H3(CH3)(OH)2 (i, 4, CH,), is produced by the
reduction of toluquinone (p. 704) with sulphurous acid, and from nitro-17 toluidine
{Beriihte, 15, 2981). It consists of needles dissolving easily in water, alcohol
and ether, and melting at 124°. It resembles hydroquinone very much, and with
toluquinone yields a quinhydrone. Caustic soda colors it bluish-green, then dark
brown.

/-Xylohydroquinone, CjH2(CH5)j(OH)2, Dioxyparaxylene (1,4, 2, 5), results
on the reduction of xylo-quinone (p. 704), and is identical with so-called hydro-
phloron, obtained from phloron (ibid). It crystallizes from hot water in pearly
leaflets, melting at 212°.

/-Xylo-orcinol, CgH2(CH3)2(OH)2 (l, 4, 3, 5) is obtained from /«-dinitro-
paraxylene (^Berichte, 19, 2318). It crystallizes from water in prisms, melting at
163° and boiling at 277-280°. In ammoniacal air it rapidly acquires a red color.
It is identical with beta-arcinol, obtained from various lichen acids (usninic acid)
by distillation.

Mesorcin, CeH(CHj)3(OH)2 = CjHijOj, dioxymesitylene, from dinitro-
mesitylene, sublimes in shining leaflets, melts at 150°, and distils at 275°. When
boiled with a ferric chloride solution, a methyl group splits oBland oxyxyloquinone
results (p. 704).

Thymo-hydroquinoiie, C,oHi,(OH), = C,H,(CH3)(C3H,)(OH)„ has
been obtained by the reduction of thymoquinone, and forms four- sided, shining
prisms, melting at 139°-

TRIHYDRIC PHENOLS.

(■ Pyrogal lie Acid (1,2,3)
CeH3(OH)3 \ Phloroglucin (1, 3, 5)
(. Oxyhydroquinone (l, 2, 4).

I. Pyrogallic Acid, CsHeOs, Pyrogallol, is formed by heating
gallic acid alone, or better, with water, to 210° : —

^«"4cO^H = C,H3(OH)3 + CO, ;

and by fusing the two parachlorphenol-disulphonic acids and
hasmatoxyhn with potassium hydroxide. It forms white leaflets or

PYROGALLIC ACID. 69S

needles, melts at 115°, and sublimes when carefully heated. It
dissolves readily in water, with more difficulty in alcohol and ether.
Its alkaline solution absorbs oxygen very energetically, turns brown
and decomposes into carbon dioxide, acetic acid and brown sub-
stances. Pyrogallol quickly reduces salts of mercury, silver and
gold with precipitation of the metals, while it is oxidized to acetic
and oxalic acids. Ferrous sulphate containing ferric oxide colors
its solution blue, ferric chloride red. Lead acetate precipitates
white, CeHsOa.PbO. An iodine solution imparts a purple-red color
to an aqueous or alcoholic pyrogallol solution. Gallic and tannic
acids react similarly.

Acetyl chloride converts pyrogallol into its triacetyl ester, CjH3.(O.C2H30)3,
which is not very soluble in water. The dimethyl ether, CjH3(O.CH3)2.0H, is
found in that fraction of beech-wood tar boiUng at 250-270°. Separated in a
pure form from its benzoyl compound it crystallizes in white prisms, melting at
51-52°, and boiling at 253°. When heated with hydrochloric acid it breaks up
into pyrogallol and methyl chloride. Different oxidizing agents (potassium
bichromate and acetic acid) convert it into ccerulignone, a diphenyl derivative.
When the acetyl derivative of the dimethyl ether is oxidized, the acetyl group
separates and the quinone compound, CgH2{O.CH3)202, results. The triethyl
ether is formed on heating pyrogallol with caustic potash and potassium ethyl
sulphate, also from triethyl-pyrogallo-carboxylic acid (see this). It melts at 39°.
Bromine converts it into xanthogallol, C^gHj^Brj^O, (Berichte, 21, Ref. 626).
The trimethyl ether melts at 47°, and boils at 235° {Berichte, 21, 607, 2020).

2. Phloroglucin, €5113(011)3 (l, 3, 5), is obtained from different resins (cate-
chu, kino), on fusion with caustic potash ; by the decomposition of phloretin and
quercetin, hesperidine, and other glucosides; by the fusion of phenol, resorcinol,
orcin or benzene Irisulphonic acid with sodium hydroxide ; also by the saponifica-
tion and decomposition of synthetically prepared phloroglucin-tricarboxylic ester,
C6(OH)3.(C02.C2H5)3 (p. 566).

It is most easily made by fusing resorcinol with caustic soda (^Berichte, 12,
503; 14, 954). It crystallizes in large, colorless prisms with i^fi; these
effloresce in the air. It loses all its water of crystallization at I JO°, melts at 218°,
and sublimes without decomposition. It has a sweetish taste, and dissolves readily
in water, alcohol and ether. Lead acetate does precipitate it; ferric chloride
colors its solution a dark violet.

Chlorine oxidizes phloroglucin to dichloracetic acid and tetrachloracetone (p.
566). One of the first intermediate products is hexachlor-triketo-hexamethylene
(p. 703) {Berichte, 22, 1469). For the action of bromine see Berichte, 23, 1706.

Phloroglucin, in most of its reactions (see Berichte, 23, 269),
conducts itself like a trihydric phenol, C6H3(OH)3 ; on the other
hand it unites with 3 molecules of hydroxylamine to form a trioxime
(see below), hence it may be considered a triketone — triketo-hexame-
thylene (p. 567) (Berichte, 19, 159). The two formulas —

™/C(OH)-CH^„Q„ , /CO.CH,\co

^^\C(OH)— CH/^"" ^°" ^"'XCO-CHj/*-^'

of which the first is derived from tertiary, the second from the sec-

696 ORGANIC CHEMISTRY.

ondary benzene ring (p. 568) are either tautomeric, or the latter
represents the unstable or pseudo-form (p. 50).

Normal ethers of pWoroglucin have been obtained by heating it with alcohol
and hydrochloric acid gas, or with ethyl iodide. The trimethyl ether, CjH,
(OCHj),, melts at 52°, and boils at 255° (Berichte, 21, 603). Its triethyl ether,
CsH3(O.C2H5)3, melts at 43°-

The dibutyryl ester occurs in the root of Aspidtum filix. It is a crystalline
substance, which yields phloroglucin and butyric acid when fused with KOH
{Berichte, 22, 463, Ref. 806).

Phloroglucintriacetyl Ester, C, 113(0.021130)3, melts at 106°. When phloro-
glucin is heated with caustic potash and alkyl iodides it yields ethers, derived
from the isomeride of triketo-hexamethylene. They are insoluble in the alkalies.
Hexamethyl-phloroglucin, C5(CH3)jOa, melts at 80° (Berichte, 22, Ref. 670;
23, 20).

Phloroglucin Trioxime, CjHjNjOj = CH /^[^•Qg|~^][^»').C:N.OH

(see above), separates, on standing, from aqueous phloroglucin with HCl-hydroxy-
lamine (3 molecules) and potassium carbonate. It is a crystalline powder. At
140° it becomes black, and at 155° explodes violently.

3. Oxyhydroquinone, CgHafOH), (i, 2, 4), is produced on fusing hydro-
quinone with KOH (together with tetra- and hexaoxy-diphenyl. Berichte, 18,
Ref. 24). It is crystalline, very soluble in alcohol and ether, and in aqueous
solution soon acquires a dark color. It melts at 140.5°. Ferric chloride colors it
a dark greenish-brown. Its tri-ethyl ether, C3H3(O.C2H5)3, is obtained from
trioxyethyl benzoic acid (from sesculetin). It can also be prepared by ethylating
ethoxy-hydroquinone. It melts at 34° {Berichte, 20, 1 133). The trimethyl
ether, C5H3(O.CH3)3, from methoxy-quinone (p. 702), boils at 247°-

Methyl pyrogallol, C3H2(CH3)(OH)3, and Propyl pyrogallol, CgH,(C3H,)
(OH),, occur in beech- wood tar as dimethyl ethers (p. 667); the latter is identical
with so-called ^zVozwon

TETRA- AND POLY-HYDRIC PHENOLS.

Tetraoxybenzenes.

(i) Symmetrical Tetraoxy-benzene, CjHj(0H)4 (i, 2, 4, 5), is obtained by
reducing dioxyquinone with stannous chloride. It crystallizes in silvery needles,
melting at 215-220°. It is oxidized to dioxyquinone (p. 702) when exposed, in
acid solution, to the air, or by ferric chloride {Berichte, 21, 2374).

Dichlortetraoxy-benzene, CjC^OH)^ (the Cl-atoms in i, 4), results in the
reduction of chloranilic acid (p. 701) with sodium amalgam, or with tin and hydro-
chloric acid, and by heating it with sulphurous acid. It forms colorless needles,
dissolving readily in water. It is reoxidized to chloranilic acid on exposure to
moist air.

Diamido-tetraoxy-benzene, Cj(NHj)j(OH)^ (^the NH, groups in I, 4), is
obtained by reducing nitranilic acid (p. 701) with tm and hydrochloric acid. It
separates as HCl-salt, C,(OH)^.(NH, HCl),, in long, colorless needles {Berichte,
18, 503; 19, 2727). Ferric chloride and other oxidizing agents convert it into
diimido-dioxy-quinone, Q ^{^l^^fi.^^^)^, a black, crystalline precipitate, which
nitric acid oxidizes to triquinoyl (p. 703).

(2) Unsymmetrical Tetraoxybenzene, C^^{0'K)^ (l, 3, 4, 5), is only
known in certain ethers. The dimethyl ether, CjHj(O.CH3)2(OH) j, is prepared
by reducing dimethyl dioxyquinone with tin chloride. It forms brilliant crystals,
melting at 158°. Caustic potash and methyl iodide convert it into the tetramethyl

TETRA- AND POLY-HYDRIC PHENOLS. 697

ether, C^^f^.CS.^^, melting at 47° and boiling at 271° (Berichte, 21, 609 ; 23,
2288).

(3) Adjacent Tetraoxybenzene, C5H2(OH)^ (i, 2, 3, 4), with the two hydro-
gen atoms in the ortho-position, is apionol, the parent substance of apiol, the
methylene dimethyl ether of allyl apionol, CgH(C3H5) (OH)^ {Berichte, 23,
2293).

Dimethyl Apionol, 05112(0.0113)2(011)2, is formed by heating apiolic acid
with caustic potash to 180°. It melts at 106°, and boils at 298°. The introduction
of methyl yields Tetramethyl Apionol, CjH2(O.CH3)j,meIting at 81° [Berichte,
22, 2482). Methylene-dimethyl Apionol, CeH2(02:CH2)(O.CH3)2, Apione,
is formed when apiolic acid loses carbon dioxide. It melts at 79°, and is volatile
with steam (Berichte, 21, 1630, 2129).

Hexoxybenzene, Cg(0H)s = CgHg05, is obtained from triquinoxyl (p. 703)
by reduction with stannous chloride and hydrochloric acid. It separates in tiie
form of small, grayish- white needles, which acquire a reddish-violet color on expo-
sure to the air. They are not fusible, but decompose about 200°. Concentrated
nitric acid oxidizes it to triquinoyl.

It forms the hexacetyl derivative, Cj(O.C2HjO)5, when heated with acetic
acid and sodium acetate. It is a crystalline mass, melting at 203° [Berichte, 18, 506).

The hexapotassium salt of hexaoxybenzene, CgOsKj, is the so-
called potassium carbon monoxide, which results upon conducting
carbon monoxide over heated potassium. It is obtained in the
preparation of potassium. Dilute hydrochloric acid, acting upon
the fresh mass, yields hexaoxybenzene [Berichte, i8, 1833).

Quercite and Finite seem to be pentahydric phenols of hexahydrobenzene,
CgHg.Hg.

Quercite, CgHjjOj = CgH,(0H)5, occurs in acorns. It can be extracted
from them by means of water. Different hexoses. accompany it, but they can be
destroyed by fermentation. It has a sweet taste, dissolves in 8 parts of water, and
crystallizes in hard prisms, melting at 235°. Five hydroxyls present in it can be
replaced by acidyls. If quercite be heated alone or together with hydriodic acid
various benzene products are obtained. Nitric acid oxidizes it to mucic and tri-
oxyglutaric acids (same as sorbinose and arabinose) [Berichte, 22, S'8).

a- and ;3- Finite, CgH,205 or CyHi^Og, occur in the resin of Pinus lamber-
tina. The first melts about 150°, the second at 187°. Both yield rhodizonic acid
when evaporated with nitric acid [Berichte, 23, 25).

Inosite, CgHjjOg + 2H2O, Phaseomannite, is a hexahydric phenol of
hexahydrobenzene. It occurs in the muscles of the heart, and in different plants
(unripe peas and beans). It forms large crystals, that weather on exposure and
then melt at 225°. There are six hydroxyl-groups in it that can be replaced by
acid radicals. If heated with hydriodic acid to 170°, it yields benzene and tri-
iodophenol. Nitric acid oxidizes it to two dioxy-, one tetraoxyquinone, and rhodi-
zonic acid [Berichte, 20, Ref. 478; 23, Ref. 26).

Phenose, is a hexahydric phenol of hexahydrobenzene, CgHg(OH)g. It has
been obtained by the action of a soda solution [Annalen, 136, 323) upon the
addition product of benzene with three mole6,ules of hypochlorous acid,

C Hg -f /nw\ • -f' '^ ^° amorphous, readily soluble substance, deliquescing in
the air. It is very much like the glucoses, has a sweet taste and reduces Feh-
ling's solution — ^but is not capable of fermentation.

698 ORGANIC CHEMISTRY.

QUINONES.

This is the designation ascribed to all derivatives of benzene in
which zH-atoms are replaced by zO-atoms. They are mostly pro-
duced by the direct oxidation of benzenes, especially the con-
densed varieties (naphthalene, anthracene, chrysene, phenanthrene),
with chromic acid in glacial acetic acid. These compounds, how-
ever, do not possess uniform character, hence various quinone
groups are noted.

The true quinones or para-quinones , whose prototype is ordinary
quinone or benzoquinone, C6H4O2, are yellow colored, volatile
compounds, having a peculiar, penetrating quinone odor, and are
readily volatilized with steam. Reducing agents (SOj, conc-HI)
easily convert them, with absorption of zH-atoms, into the corres-
ponding colorless dioxy-compounds (hydroquinones) : —

CjH^CO,) + H^ = C,H4(0H)„ Hydroquinone (i. 4).

Hence they oxidize readily, and may be compared to the per-
oxides (like acetyl peroxide {Q^Sy)fi^- The two oxygen atoms
take the para-position in the benzene nucleus, and the para-quinones
therefore are readily produced by oxidation of the para-di-derivatives
of the benzenes.

It is usually supposed that in the ordinary quinones the zO-atoms are linked
by one valence to each other; it is, however, possible, that they ought to be con-
sidered as di-ketones having aCO-groups : —

C O CO

HC CH

I II
HC CH

HC CH

II II
HC CH

\/

C O CO

The fact that in the different reactions the 20-atoms are invariably separated by
only two monovalent atoms or groups (in the action of PCI5) forming normal ben-
zene derivatives, CgXj ; furthermore, the simple relations of the quinones to the
quinone-chlorimides and indophenols (p. 705), argue for the first view.

According to the second formula the quinones are derivatives of a reduced ben-
zene nucleus, dihydrobenzene, CgHg (p. 568), and are to be 'isxra^i diketo-dihydro-
benzenes. In support of their ketone nature we have their ability to yield quin-
oximes with one molecule of hydroxylamine (these are identical with the nitroso-
phenols). A stronger proof is the production of quinon-dioxime, HO.N:

C(' ^rr ~ j-,jT yC:N.OH, by the union of quinone with two molecules of hy-
droxylamine (p. 67s). The production of bromine additive products might be an
additional argument {Jr. pr, Ck., 42, 61 ; Berichte, 23, 3141).

Yet, the quinones of the benzene series are not capable of combining with
phenylhydrazine, but are only reduced by it, while the naphthaquinones and
phenanthraquinones form hydrazides {Berichte, 18, 786).

QUINONES. 699

Another series of quinones (;8 naphthaquinone, anthraquinone, phenanthraqui-
none) must be considered true diketones (with 2CO-groups). They are non-vola-
tile and odorless, and are tHhet para-diketones (like anthraquinone) or ortho-dike-
tones {e.g., j3 naphthaquinone and phenanthraquinone). Sulphurous acid reduces
the latter to the corresponding hydroquinones ; they form anhydro-compounds
with the aldehydes and ammonia.

There exist, finally, the quinones with two nuclei, e.g., coerulignone, derived
from diphenyl. In these the zO-atoms link two benzene nuclei.

Quinone, CeH^Oj, Benzoquinone, was first obtained by distilling
quinic acid with MnOj and sulphuric acid. It is formed from many-
benzene compounds, especially those di-derivatives belonging to
the para -series (e.g., para-phenylene-diamine, araidophenol, phenol
sulphonic acid and sulphanilic acid), when they are oxidized with
MnOj and sulphuric acid, or with a dilute chromic acid mixture.
Benzidine, Ci2Hg(NH2)2, likewise yields a considerable quantity of
quinone. Hydroquinone is oxidized to quinone even on boiling
with a ferric chloride solution. It is, however, best prepared
(according to Nietzki) by oxidizing aniline with chromic acid.

Preparation. — Oxidize aniline in sulphuric acid solution, just as was done in the
case of hydroquinone (p. 691), adding, however, a little more sodium bichromate
to effect the complete oxidation to quinone, then extract with ether. A better
course is to prepare the quinone from hydroquinone already prepared ; to this end
dissolve the latter in as little water as possible, add two parts of sulphuric acid,
and while cooling introduce the sodium bichromate solution, until the precipitate
consists of pure yellow quinone. This is filtered at once (Berichte, ig, 1468 ; com-
pare Berichte, 20, 2283).

Quinone crystallizes in golden-yellow prisms, melts at 116°, and
sublimes at medium temperatures, in shining needles. Its vapor
density confirms the formula CeH^Oj. It possesses a peculiar, pene-
trating odor, distils readily with steam, and dissolves easily in hot
water, alcohol and ether. It turns brown on exposure to sunlight.
Reducing agents (SO2, Zn and HCl) convert it first into quin-
hydrone and then into hydroquinone. PClj changes it to para-
dichlorbenzene, QHiClj.

Quinone forms chlor- and brom-hydroquinone with concentrated hydrochloric
and hydrobromic acids (p. 692). It also unites with two molecules of acetyl
chloride to form diacetyl-chlorhydroquinone, CgH^Oj + zC^HjOCl = CgH,
C^O.CjHjO)^ + HCl {Berichte. 16, 2096). Quinone yields quinoxime, CgH^O:
N.OH (/-nitrosophenol) and quinon-dioxime, HO.NiCjH^iN.OH (p. 675), with
hydroxylamine hydrochloride. All true para quinones show a like reaction in acid
solution. Their dioximes do not form anhydrides. They unite with acetic anhy-
dride to diacetyl compounds. Di-nitrosobenzenes are produced by the oxidation
of their alkaline solutions (also on exposure to the air). Nitric acid oxidizes
them to di-nitrobenzenes {Berichte, 21, 428). Orthoqninones, or ortho-diketones
(p. 6g8), and their monoximes, when in alkaline solution, unite with hydroxylamine
to form dioximes, capable of yielding anhydrides {Berichte, 23, 2815).

The quinone monoximes and phenylisocyanate unite and yield carbanilides. The
dioximes combine with two molecules of CjHj.N:CO, and form dircarbanilides.

700 ORGANIC CHEMISTRY.

They are partly changed to anhydrides {Berichte, 22, 3105). Of the substituted
quinones, only those quinone or CO-groups react with phenylisocyanate, in which
the adjacent positions (ortho) are not replaced {Berichte, i,i., 3316, 3493)-.

When the primary amines and anilines act upon the quinones, the following may
occur : —

(1) Either the quinone oxygen is replaced by the imide-group : NR, with the
production of quinone-imides and quinone-diimides, e.g., CjH^OiN.C^Hj and
CeHj.N.-CeH^iN.CeHj.

(2) Or, the hydrogen of benzene is substituted. Then anihdo-quinones result.
At the same time, quinone is reduced to hydroquinone (Berichte, 18, 785) : —

(i, 4).
3C,HA + 2CeH5.NH, = C,Hp,<;^NH.^,H5 (2) ^ 2CeH,(0H),.

Dianilido-quinone.
Such compounds are readily obtained from oxy-quinones. Again, the oxy-quinone
imides, Rr^/->ti, and the quinone- amides, R\ >iji , are sometimes tautomeric (Be-
richte, 23, 897).

Dianilido-quinone, CjjHj^NjO,, Quinone-anilide, is formed by boiling
quinone with aniline and alcohol. It forms brownish-violet scales, with metallic
lustre [Berichte, 16, 1556). In the presence of acetic acid the product is Diani-
lido-quinone-anilide, CgH,0(N.CeH5)(NH.CeH5lj (Berichte, 18, 787), while
by fusing quinone with aniline or aniline hydrochloride, we obtain Dianilido-
quinone-dianilide, CjH2(N.C5H5),.(NH.C5H5), (1,4, 2,5) = CjoHj^N^, Azo-
phenine (Berichte, 21, 683 ; 21, Ref. 656).

The latter is also produced by the action of aniline upon amidoazobenzene,
/-nitrosophenol and /-nitrosodiphenylamine (Berichte, 20, 2480). It consists of
garnet-red needles, melting at 241°. It dissolves with a violet color in oil of vitriol.
It becomes blue in color at 300°. It changes to fluorindin when heated
(Berichte, 23, 2791). The induline dyes are intimately related to azophenine.

The quinones react similarly with the phenylene diamines (Berichte, 23, 2793).

Phenylhydrazine reduces the quinones of the benzene series to hydroquinones,
whereas the naphthaquinones and phenanthraquinone yield hydrazones.

The phenols and quinones form compounds containing 2 molecules of the mono-
valent phenols (Annalen, 215, 134). Phenoquinone, C5H4O2.2CgHj.OH, crys-
tallizes in red needles, melting at 71°. It is very volatile. Caustic potash colors
it blue, and baryta water green. An analogous compound is —

Quinhydrone, Cj gHj ^O^ = CgHjO^CsH^COH),. This is produced by the
direct union of quinone with hydroquinone. It appears as an intermediate product
in the reduction of quinone or in the oxidation of hydroquinone. It consists of
green prisms or leaflets with metallic lustre, melts readily, and dissolves in hot
water with a brown, in alcohol and ether with a green, color. When it is boiled
with water it decomposes into hydroquinone and quinone, which distils over. It is
changed by oxidation to quinone, and by reduction to hydroquinone.

Chlor- and irow-quinones are obtained by the substitution of quinone or by the
oxidation of substituted hydroquinones (p. 692) with nitric acid.

Trichlorquinone,Q,^i^(0^,\s produced, together with tetrachlorquinone ;
it consists of large, yellow plates, melting at 166°. It forms tetrachlorhydro-
quinone, CgCl4(0H)j, by heating with fuming hydrochloric acid. Fuming nitric
acid oxidizes this product to tetrachlorquinone.

QUINONES. ^ 701

Tetrachlorquinone, C^QX^(fi^, Chloranil, is obtained, together with trichlor-
quinone from many benzene compounds (aniline, phenol, isatin) by the action of
chlorine or potassium chlorate and hydrochloric acid. Its production from sym-
metrical tetrachlorbenzene (p. 582) by boiling with nitric acid is theoretically
interesting.

In order to prepare it, gradually add a mixture of phenol (l part) with CIO3K
(4 parts) to concentrated hydrochloric acid, diluted with an equal volume of
water, and apply a gentle heat. At first red crystals separate out, but on the
addition of more CIO3K these become yellow. The crystalhne mass consists of
tri- and tetra-chlorquinone. To effect their separation, they are changed by SOj
to hydroquinones (tetrachlorhydroquinone is insoluble in water) and the latter
oxidized with nitric acid (Berichte, 10, 1792, and Annalen, 210, 174).

Chloranil consists of bright golden leaflets, insoluble in water, but soluble in hot
alcohol and ether. It sublimes about 150°, in yellow leaflets. PCI 5 converts it
into CgClg. It oxidizes and serves as an oxidizing agent in the manufacture of
coloring matters. Chloranil dissolves with a purple-red color in dilute KOH,
iorming potassium chloranilate, C^C\^{0^{(^Y^,^ -\- H^O, which crystallizes in
dark red needles, not very soluble in water. Acids set free chloranilic acid,
C5Cl2(02)(OH)2 4" HjO, which consists of red, shining scales. Aqueous ammonia
converts chloranil into chloranilamide, C.Cl2(02)(NH„),, and chloranilamic acid,
CeCl,(0,).(NH,)OH.

The brom-quinones are perfectly analogous to the chlorine derivatives. Tetra-
bromquinone, Bromanil, CgBr^02, is obtained by heating phenol (i part) with 10
parts of bromine and 3 parts of iodine in 50 parts of water. It consists of golden-
yellow, shining leaflets or thick plates, which melt and sublime. By dissolving
tetra- or tri-bromquinone in dilute caustic potash we obtain the potassium salt of
bromanilic acid, C5Brj(02)(OH)j, crystallizing in dark red needles or bronze-
colored leaflets. Bromanilic acid is formed by allowing bromine to act upon
dioxyquinone-dicarboxylic acid, C5(Oj)(OH)j(COjH)2, and it, therefore, contains
two bromine atoms in the para-position (Berichte, 20, 1303 and 1997).

Nitranilic Acid, C5(NO,),0,(OH), = (NO,)c(^^(°^) -q^^\c(NO,),

or (N02)HC/^Q~ ^q'^CH(N02) (see Berichte, 22, Ref. 292), analogous to

brom- and chloranilic acid, is formed from quinone and hydroquinone with nitrous
acid ; more readily from diacetyl-hydroquinone with fuming nitric acid, or by the
action of sodium nitrite upon chloranil {Berichte, 22, Ref 292). It also results
from dioxyterephthalic and dioxyquinone-terephthalic acids by the action of fuming
nitric acid; the two NOj- and OHgroups are, therefore, in the para-position
(Berichte, ig, 2398 and 2727). It crystallizes with water in golden yellow needles
or plates, melts in its water of crystallization, becomes anhydrous at 100°, and
detonates at 170° without melting, llae potassium salt, C5(NOj)2(02){OK)2,
forms yellow needles, soluble with difKculty in water. When nitroanilic acid is
reduced it yields diamidotetroxybenzene (p. 696).

We may look upon chlor-, brom- and nitranilic acids as derivatives of dioxy-
quinone, CjH2(02)(OH)2.

Diketo-hexamethylene, C5H8O2 = CO('(-.jj^ CH^/*"*^' ^'''"'^^y^^''^''^-

none, is a derivative of hexahydrobenzene or hexamethylene. It results upon
expelling two molecules of carbon dioxide from succino-succinic acid. It forms
colorless crystals, melting, at 78° {Berichte, 22, 2170). It forms a dioxime with

702 ORGANIC CHEMISTRY.

hydroxylamine, CsHgfN.OH)^. Sodium and alcohol reduce this to p-diamido
hexamethyUne, C^lA^i^Yl^^. Phenylhydrazine converts tetrahydroquinone into
a dihydrazone. Hydrocyanic acid converts it into the dicyanhydrin, C5Hj(OH)2
(CN)j, etc. iJSerichte, 22, 2176).

OXYQUINONES AND POLYQUINOYLS.

Oxy-quinone, Cg.HjfOj).©!!.
Dioxyquinone, C5H2(OH)20j.
Tetroxyquinone, Ce(OH),Oj.
Dioxydiquinoyl, C^O^^O^) (,OH)j.
Triquinoyl, Cg(0j)3.

Oxy-quinone, CgH3(02).OH. Its methyl ether is produced by oxidizing
«-amido-anisoI, CgHjiNHjJ.O.CHj, with potassium permanganate and sulphuric
acid. It consists of yellow needles, melting at 140°. Sulphurous acid reduces it
to methyl-oxy-hydroquinone (p. 696) [Berichte, 21, 606).

Dioxyquinone, CsHj(02)(OH)2 (I, 2, 4, 5), is obtained from dioxyquinone
dicarboxylic acid, Cg(02)(OH)2(C02H)j (its sodium salt), by boiling with hydro-
chloric acid, by the oxidation of diamido-resorcin in alkaline solution (Berichie,
21, 2374; 22, 1288) and by the action of sulphuric acid upon dianilidoquinoue
(Berichte, 23, 904). It separates in small blackish-brown crystals, which sublime
above 185°- It dissolves in alcohol with a deep red, in alkalies with a bright
yellow color. Acids reprecipitate it in the form of a dark yellow crystalline
powder. Stannous chloride reduces it to symmetrical tetraoxy-benzene (p. 696)
and dianilidoquinone, CsH2(Oj)(NH.C5H5)j, is produced when it is healed with
aniline (p. 700). Hydroxylamine hydrochloride converts it into a dioxime, CjH,
(N.0H)2{0H)j, that yields diamidohydroquinone by reduction.

Diquinoyl, C^Yi.^(0^{0^ ( i , 2, 3, 4), is not known in a free condition. Dinitro-
resorcin (p. 627) is its dioxime, CgH2(02)(N.OH)j, from which hydroxylamine
produces diquinoyltetroxime, C5Hj(N.0H)^ (i, 2, 3, 4) i^Berichte, 23, 2816,

S'.W)-

Tetraoxy-quinone, Cj(02)(OH)4, formerly called dihydrocarboxylic acid, is
obtained by oxidizing the aqueous solution of hexaoxybenzene (p. 697) by exposure
to the air. It may also be obtained from diamido-dioxyquinone {^Berichte, 21,
1853). The disodium salt, C502(OH)j(ONa)j, separates in metallic black
needles, if the aqueous solution of hexa-oxybenzene, mixed with soda, be allowed
to stand exposed to the air. When the salt is boiled with dilute hydrochloric
acid, tetroxyquinone separates in black needles with a green, metallic reflex
{Berichte, 18, 507, 1837). It is not fusible, but readily soluble in hot water and
alcohol. It is a strong dibasic acid.

Dioxydiquinoyl, Cs(02)(0j)(0H)j, called rhodixonic acid, is prepared by
reducing triquinoyl, CgjOjjj, by digesting it with aqueous sulphurous acid
{Berichte, 18, 513). It consists of colorless leaflets, very readily soluble in water;
it decomposes quite rapidly in aqueous solution. The corresponding sails are
obtained by saturaling the aqueous solution with potassium and sodium carbonate.
"^h^ potassium, salt, C504(OK)2, may also be made by washing polassium-hexa-
oxy-benzene (potassium carbon monoxide, p. 697) with alcohol. It forms dark
blue needles, dissolving in water with an intense yellow color. The sodium salt,
'-•6^4(ONa)2, consists of violet needles, or shining octahedra {Berichte, ig,
1838).

LEUCONIC ACID. 703

Dioxy-diquinoyl is probably a para- and ortho-diketone ; its two hydroxyls
occupy the ortho-position with reference to each other (Berichte, 23, 3140) : —

/ CO CO ,

CO(^ ^CO, Dioxydiquinoyl.

\C(OH).C(OH)/ .

In consequence it yields with orthotoluylene diamine (one molecule) a diazine
(p. 628), from which a diquinoyl can be prepared by oxidation. This is capable
of combining further with two molecules of o-toluylene diamine and forming a
triazine- or triphenazine-derivative (Berichte, 20, 322).

Hexachlor-triketone, CgClgOs = CCIj/^q^^I^^CO, is produced when

chlorine acts upon a chloroform solution of phloroglucin [Berichte, 22, 1467). It
forms colorless crystals with a disagreeable odor. It melts at 48°, and boils at
269°. Stannous chloride reduces it to trichlorphloroglucin, 0^013(011)3. Water
decomposes it into dichloracetic acid, tetrachloracetone and carbon dioxide :
CeCleO, + 2H2O = OHCla.COjH -f COCOHClj)^ + COjj {Berichte, 23,
230).

Triquinoyl, Cfi^ + 8HjO = CO('^q~cO/'^° + SH^O.hexaketo-hexa-
methylene {Berichte, 20, 322), results upon oxidizing dioxydidiuinoyl and diamido-
tetroxybenzene (p. 696) with nitric acid. It is a white, micro-crystalline powder
{Berichte, 18, 504). It melts about 95°, giving up water and CO2. It is like-
wise decomposed by warming it with water to 90°. Stannous chloride reduces it
to hexa-oxy-benzene, which is oxidized in alkaline solution to tetraoxyquinone,
Cg(02)(OH)4, and dioxydiquinoyl, 05(02)2(011)2 (see above).

Triquinoyl, hexaoxybenzene and their derivatives, in various oxidation reac-
tions, give off carbon dioxide and yield croconic acid, C5H2O5, which by more
energetic oxidation becomes leuconic acid, C5O5 + 4H2O. Both substances are,
in all probability, derivatives of pentamethylene (p. 520), and correspond to the
formulas {Berichte, ig, 308, 772) : —

,C(OH)— CO .00— CO

C0< I and C0( I .

^00 — C(OH) ^CO— CO

Croconic Acid. Leuconic Acid.

For the course of the transformation of the benzene ring into the pentamethylene
ring see Berichte, 20, 1267 and 161 7.

Croconic Acid, CjHjOj = 0503(0!!),, is produced by the alkaline oxidation
of most of the hexa substituted benzene-derivatives, e. g., hexaoxybenzene, dioxy-
diquinoyl, diamido-tetroxy-benzene, etc. Triquinoyl, when boiled with water,
decomposes into carbon dioxide and croconic acid : —

CeOs + H2O = C5H2O5 + CO2.

Free croconic acid crystallizes with three molecules of water in sulphur-yeljow
leaflets; it loses its water of crystallization at 100°. It dissolves very readily in
water and alcohol. Its potassium salt, CjOjKj + 3H2O, crystallizes in orange
yellow needles. When oxidized-wiih nitric acid or chlorine the product is —

Leuconic Acid, C5O5 + 4HjO, Pentaketo-penta- methylene, which is recon-
verted into croconic acid by sulphur dioxide. It is very soluble in water, but dis-

704 ORGANIC CHEMISTRY.

solves with dfficulty in alcohol and ether. It crystallizes in small colorless
needles. Being a pentaketo compound it unites with five molecules of hydroxyl-
amine, forming the penta-oxime, C5(N.OH)5. A tetroxime, C5(N.0H)^0, is
produced at the same time. Stannous chloride reduces these oximes to penta-
amido-pentol, C5H(NHj)5, and tetra-amido-oxy-pentol, C5H(OH)(NHj)^
(Berichte, 22, 916). As a diorthoketone it unites with two molecules of toluylene-
diamine and forms the diphenazine, C50(N,C,H5)j, which as a ketone is capable
of combining with one molecule of phenylhydrazine (Berichte, ig, 777).

With naphthalene there is known, in addition to the ordinary a-naphthaquinone
(corresponding to ordinary quinone), an isomeric /3-naphthaquinone, which is
an orthodiketone (CO.CO — ) (p. 698). The o-Benzoquinone, CgH^O^ =

CH^ „ ~ ^CB., corresponding to it, is only known in its halogen-derivatives.

Tetrachlor- and Tetrabrom-o-benzoquinone, CgBr^Oj, are produced by
oxidizing tetrachlor- and tetrabrom-pyrocatechin, 0.^x^(0)^)^ (l, 2), with nitric
acid. Both form crystals with a garnet-red color and show a metallic lustre. The
first melts at 132°; the second at 151° (Berichte, 20, 1778).

The homologous quinones are quite similar to benzoquinone.

Toluquinone, C5H3(CH3)02, is obtained by oxidizing various amidotoluenes.
It is most convenieritly prepared by oxidizing o-toluidine (crude) with chromic
acid (Berichte, 20, 2283), just as in the case of benzoquinone. It consists of
golden yellow leaflets, melting at 67°; these are very volatile and have the
quinone odor. Reduction (with SO2) converts it into tolu-hydroquinone fp. 694).
Hydroxylamine converts it into the monoxime, CgH3(CH3)0:N.OH, identical
with nitroso-o-cresol (p. 685), and toluquinon-dioxime, C5H3(CH3)(N.OH)2,
which is also obtained from nitrosotoluidine (p. 623) (Berichte, 21, 733). It forms
yellow needles, chars at 210°, and detonates at 234°. When it is oxidized in
alkaline solution it yields dinitrotoluene. Aniline and toluquinone yield anilides
(p. 700).

Xyloquinones, CgH2(CH3)202. The three possible isotnerides are known.

o-Xyloquinone (i, 2, Oj), is obtained from amidoo-xylene by oxidation with
KjCr^O,. It sublimes in yellow needles, melting at 55° (Berichte, 18, 2673).
zw-Xyloquinone (i, 3, Oj) is obtained from amido-w-xylene and amidomesi-
tylene, by the displacement of a CH3-grbup (Berichte, 18, 1150). It melts at 73°.
The oxidation of diamido- or dioxymesitylene, by chromic acid, produces oxy-m-
xyloquinone, melting at 102°. The yellow aqueous solution is colored a deep
violet by alkalies, or even by spring water.

/-Xyloquinone, CgH2(CH3)202 (l, 4, O^), results by the oxidation of
/-xylidine, or more readily from diamido-xylene (obtained by the decomposi-
tion of amido-azo-xylidine). It is identical with phloron. It is most easily
obtained from pseudociimidine, 0^112(0113)3, NHj, by oxidation with chromic
acid (Berichte, 18, 1 150). It consists of golden yellow needles, which resemble
quinone in odor, and melt at 123°. With hydroxylamine it forms (like quinone)
a monoxime and dioxime (Berichte, 20, 978).

Durenequinone,05(0H3)4O2(i,2,4, 5,02),is produced by oxidizing diamido-
durene with ferric chloride or sodium nitrite. It forms long yellow needles, melt-
ing at 111°.

QUINONE-CHLORIMIDES. 705

Thymo-quinone, C6H3(CH3)(C,H,)Oj, Thytnoll, is formed by oxidizing
thymol or carvacrol (p. 688) with MnOj and HjSO^, or amidothymol with ferric
chloride. It forms yellow plates, melts at 45.5°, and boils at 232°. By reduction
it yields thymohydroquinone (p. 694). With hydroxylamine it yields a monoxime
(nitrosothymol, p. 68&). See Berichte, 22, 3268, upon iodo- and bromthymo-
quinone.

Two Oxythymoquinones, CiqHjj(OH)0, and Dioxythymoquinone, C,jH,(,
(OH)202, are produced on healing bromthymoquinone with KOH. They yield
thymodiquinone, CiqHjj(Oj)(Oj), by oxidation (Berichte, 23, 1391 ; Ref. 565).

QUINONE-CHLORIMIDES.

These are very similar to the quinones, and possess an analogous constitution
(p. 698). We must regard them either as diketones or peroxides, in which oxygen
is replaced by the group NCI. The latter view corresponds to the formulas : —

.0 .0 ^NCl ,NC1

C^HX or C,H,( I and C,H,^ or C^H / |

^NCl ^NCl ^NCl ^NCl.

, ^ ■ Quinone Chlorimide. ^ Quinone Dichlorimide,

They are produced from /amidophenols and ^-phenylene diamines (their HCl-
salts) by oxidation with an aqueous solution of bleaching lime. The mono-
chlorimides form the indophenol coloring matters (see below) with phenols and
tertiary anilines.

Quinone Chlorimide, C5H4(ONCl), produced from HCl-para- amidophenol
with bleaching lime (Journ. pr. Chem. 23, 435), forms golden yellow crystals,
which melt at 85°, volatilize readily with steam and smell like quinone. It is
easily soluble in hot water, alcohol and ether. Reducing agents (also H2S) con-
vert it into /-amidophenol. When boiled with water it decomposes into NH^Cl
and quinone.

Quinone-dichlorimide, CgH4(N2Cl2), from paraphenylenediamine-hydro-
chloride, crystallizes in needles which deflagrate at 124°, and are converted by
reducing agents into^-phenylene-diamine.

Dibrom-quinone-chlorimide, C5Br2H2(ONCl), from dibrom-/ nitro-phenol,
crystallizes in dark yellow prisms, melting at 80° and decomposing at 121°.
Trichlor-quinone-chlorimide, CgCl3H(0NCl), from trichlor-/-amidophenol,
forms yellow prisms, melting at 118°.

Indophenols , Indoanilines and Indoamines. — These are green to
•blue-cblored dye-substances. In constitution they are analogous to
the quinone-chlorimides and quinone-dichlorimides ; they bear a
close genetic relation to the latter, and are obtained by allowing
the quinone-chlorimides and -dichlorimides to act upon phenols
and anilines : —

.0 ' yO -NH.HCl

C^H / I CeH / I C,H / |

\n.C,H,.OH ^N.CeH,.N(CH3)2 ^N.C^H^.NHj

Indo-phenol , Incfo-aniline, Indo-amine,

Quinone-phenoiimide. Quinone-dimethyl-aniUnimide. Phenylene Blue.

59

706 ORGANIC CHEMISTRY.

These compounds also contain the chromophore groups O — N and
N — N (see p. 644), which occupy the para-position in one benzene
nucleus; they are also closely related to the thionine dyestuffs (p.
605). They are decolorized upon reduction (the addition of 2H-
atoms) which is true of most coloring compounds. By this action
the chromophore group is severed, and derivatives of diphenyl-
amine are formed, which are their leuco-compounds (p. 605). Thus,
by reducing (dibrom) quinone-phenolimide we obtain (dibrom)
/-dioxydiphenylaraine (p. 604), and the same treatment converts
indoaniline into dimethylamido-oxy-diphenylamine, and phenylene
blue into/-diamido-diphenylamine (p. 603) : —

„ /C,H,.OH „ /CeH,.OH jjj^/C„H,.NH,

, H%c3H,.OH "%C,H,.N(CH3), "^\CeH,.NH,-

/-Dioxydiphenylamine. Dimethyl-amido-oxy- Diamido-diphenylamine,

diphenylamine.

Therefore, the indophenols, indoanilines and indoamines may be
viewed as derivatives of diphenylamine, in accordance with the fol-
lowing formulas of like significance as those above (Nietzki, Be-
richte, 21, 1736): —

j^XC^H.-O I \C,H,.0 ^\CeH,.NH •

Indophenol, Indoaniline, Indoamine.

The connection of the three groups is evident from the fact that the
indoamines, by the replacement of the amido-group by oxygen, can
be converted into indoanilines, and the latter, furthermore, into
indophenols (Mohlau, Berichte, 16, 2843, and 18, 2915).

(i) The indophenols, in addition to their formation from the action of quinone
chlorimide upon phenol, are also produced by oxidizing a mixture of a para-
amido phenol and phenol (i molecule of each). They dissolve in alcohol with a
red color, and possess a phenol-like character. Their salts with the alkalies and
ammonia dissolve in water with a blue color.

Quinone-phenol-imide, ^C n^vi^ r\ < also results upon heating phenol-

blue with soda-lye {Berichte, 18, 2916), but owing to its instability, cannot be.
obtained in a free condition. Dibrom-quinone-phenolimide, Nc^ p^u^g. n-

Its sodium salt is produced by the action of dibromquinone-chlorimide in alcoholic
solution upon an alkaline phenol solution. It separates in golden green crystals,
which dissolve in water with a blue color. Free dibrom-phenolimide, separated
from its sodium salt by acetic acid, crystallizes in dark red prisms having a metallic
lustre; they dissolve in alcohol and ether with a fuchsine-red color. Strong
mineral acids decompose it into dibromphenol and quinone.

NAPHTHOL BLUE. 707

(2) The Indo-anilines (indophenols of Witt), as

I \<-6"4-^, I XCioHs-O

Phenol Blue. Naphthol Blue.

are produced: (i) by the action of quinone chlorimide upon dimethylaniline in
alcoholic solution (see above) ; (2) by the action of nitroso- and nitro-dimethyl-
aniline upon phenol and a-naphthol in alkaline solution, especially in the presence
of reducing agents (Witt, 1879) : —

0N.C,H,.N(CH3), + C.Hj.OH =N/^«g*'N(CHs),.

Nitrosodimethylaniline. I N"-'6*'^4-'j-'

Phenol Blue.

(3) By the oxidation in alkaline solution (with spdium hypochlorite), of a mix-
ture of a para-phenylene diamine with a phenol, or of a paraamido-phenol with a
primary monamine ; this is the readiest method for its preparation. Thus there is
formed from dimethyl-/-phenylene diamine (p. 625) with o-naphthol, the so-called
naphthol blue ; —

H,N.CeH,.N(CH3), + q„H,.OH + O, = N<^g«^^«-^(J^|\»^0.

Naphthol Blue.

The indoanilines, in distinction to the indophenols, are feebly basic, and are not
capable of forming salts with alkalies. They are rather stable towards the latter;
acids quickly decomposethem into quinones and the /-phenylene diamines. They
are changed to the leuco-compounds by reduction (absorption of two hydrogen
atoms) ; these dissolve readily in alkalies, and are readily reconverted (oxidized)
into indoanilines (by exposure of their alkaline solution to the air). The free indo-
anilines have a deep-blue color, and can be applied as dyestuffs. For this purpose
they are converted into their alkaline leuco-derivalives, which are soluble, and the
material is impregnated or printed with these. Oxidation (by exposure to the air,
or with K,Cr„0,1, develops the color. The simplest aniline is Quinone Anilin-

/N.CeH^.NH,
imide, C^/ \ , a violet dye, formed by the oxidation of /-phenylene

\o

diamine, CeH,(NH„)2, with phenol. Its dimethyl derivative is Quinone-di-

N.C,H,.N(CH3),
methyl-anilinimide, CgH^^' | ,

Phenol Blue.- This results from dimethyl-/-phenylene diamine and phenol.
It has a greenish-blue color. When boiled with soda-lye it splits off dimethyl-
amine and becomes quinone phenolimide.

N.C,H,.N(CH3),

Naphthol Blue, CjjHg^ | , called 2«(/i7/^?«o/ (Koechlin and

^O
Witt), finds technical application. It is made by oxidizing dimethyl-/-phenylene
diamine with a-naphthol {Berichte, 18, 2916), or by the action of nitrosodimethyl-
aniline upon a-naphthol. It crystallizes from alcohol in bronze-like, bluish violet
crystals, dissolves without coloration in acids, and on standing in contact with the
same decomposes into dimethyl-/-phenylene diamine and a-naphthoquinone. When
reduced with SnClj, it yields the SnCl^- double salt, which occurs in commerce as
a paste, bearing the name " white indophenol."

7o8 ORGANIC CHEMISTRY.

(3) Indamines (see above).

These arise by oxidation, in neutral solution and in the cold, of a mixture of a
/■phenylene diamine with an aniline (Nietzki), or by the action of nitrosodimethyl
aniline upon anilines or »?-diamines (Witt). They are feeble bases, forming blue
or green- colored salts with acids, but with an excess of the latter are very easily
split up into quinone and the diamine. Because of their instability they find no
application, and are only important as intermediate products in the manufacture of
safranine dyestuffs (into which they can be readily transposed) {Berickte, 16, 464).
The simplest ind amine is —

Phenylene Blue, C^HnNs = N^^«^*"^^2 This is produced by the oxi-
dation of/-phenylene diamine with aniline. Its salts are greenish-blue in color.
It yields diamido-diphenylamine by reduction. Its tetramethyl-derivative is —

Dimethylphenylene Green, CijHigNj.HCl = N<^^«g*'^[^][][']''Q (Bind-

schedler's green). This is obtained by oxidizing dimethyl paraphenylene diamine
with dimethyl aniline. Its salts dissolve in water with a beautiful green color, and
impart a yellow-green color to silk. Its reduction yields tetramethyl-diamido-di-
phenylamine (p. 604). Digestion with dilute acids resolves it into quinone and
dimethylamine {Berichte, 16, 865). When it is boiled with soda-lye, dimethyl-
amine splits off and phenol blue is produced; this further separates into quinone
phenoUmide (p. 706) {Berickte, 18, 2915).

Toluylene Blue, CisHuN^ = N;^^«g*-,-^(^^|J|j, results from ordinary

toluylene diamine (p. 6z6) by oxidizing it mixed with dimethyl/-phenylene dia-
mine, or by the action of HCl-nitroso-dimethylanihne. Its salts with one equivalent
of acid are of a beautiful blue color, and are decolorized by an excess of mineral
acids with formation of the diacid salts. It is converted into toluylenered (seethis)
on boiling with water.

The lowest homologue of toluylene blue is produced by reducing dimethylamido-
dinitro-diphenylamine (p. 604), and oxidizing the resulting triamido-compound
{Berichte, 23, 2738).

ALCOHOLS.

The true alcohols (isomeric with the phenols) of the benzene
series are produced by the entrance of hydroxyls into the side-
chains of the homologous benzenes (p. 557). They are perfectly
analogous to the fatty alcohols. By oxida,tion they yield aldehydes
(or ketones) and acids : —

CgHj.CHj.OH CjHj.CHO C.Hs.CO.OH.

Benzyl Alcohol. Benzaldehyde. Benzoic Acid.

The methods of forming them are perfectly analogous to those of the fetty
series. They are obtained : —

I. By the conversion of substituted hydrocarbons, like benzyl chloride, CgHs.
CHjCl, into acid esters, and saponifying the latter with alkalies, or by boiling the
chlorides with water and lead oxide (p. II 9), or with a soda solution : —

CsH,.CH,Cl + HjO = CeHj.CHj.OH -f HCl.
Benzyl Chloride. Beftiyl Alcohol.

BENZYL ALCOHOL. 709

2. By the action of nascent hydrogen (p. 119) on the aldehydes and ketones,
or by heating the aldehydes, or letting them stand with alcoholic or aqueous potash,
whereby acids are formed at the same time : —

2CeH5.CH0 + KOH = CeHj.CHj.OH + CsHj.COjK.

In this series we also distinguish primary, secondary and tertiary alcohols.

Benzyl Alcohol, QHsO = C6H5.CH2.OH, occurs as benzyl-
benzoic ester, and benzyl-cinnamic ester in the balsams of Peru
and Tolu, and in storax, and can be obtained from benzaldehyde
(oil of bitter almonds) by the action of sodium amalgam or aque-
ous potassium hydroxide \Berichte, 14, 2394), or by boiling benzyl
chloride with a soda solution. It is a colorless liquid, with a
faint aromatic odor, and boils at 206° ; its specific gravity at 0° is
1.062. It dissolves with difficulty in water, but readily in alcohol
and ether. It yields benzaldehyde and benzoic acid when oxidized.
Heated with hydrochloric acid or hydrobromic acid, the OH-
group is replaced by halogens. Benzoic acid and toluene result on
distilling it with concentrated potash : —

S^HjO + KOH = CjH^KOj + 2C,H8+ 2H2O.

The esters of benzyl alcohol are produced from it by the action of acid chlorides,
or from benzyl chloride by boiling with organic salts. The acetic ester, C,H,0.
CjHgO, is a liquid and boils at 206°. The oxalic ester, CjO^(C,H,)2, forms
shining leaflets, melting at 80°.

The alcohol ethers are obtained by heating benzyl chloride with sodium alco-
holates. 'Y'he methyl ether, C^ii^O.CH.^,ho\\s at 168°; ihc ethyl ether &t 185°.

The dibenzyl ether, (CgH5.CH2)20, is formed on heating the alcohol with
boric anhydride, and benzyl chloride with water to igo°. It is an oil boiling
near 310°.

The benzyl-phenyl ether, CgHj.CH^.O.CjHj, results when benzyl chloride is
heated together with potassium phenolate, C5H5.OK. It melts at 39°, and boils
at 287°.

Substituted henz^X alcohols are derived from substituted benzyl chlorides, e. g.,
CjHjCl.CHjCl, when they are heated with aqueous ammonia, or by, means of
acetic esters. Para-chlor-benzyl alcohol, CgH^Cl.CHj.OH, consists of long
needles, which melt at 66°, and boil about 220°.

o-Nitrobenzyl Alcohol, C5H4(N05).CH2.0H, is formed by shaking »-nitro-
benzaldehyde (crude) with concentrated sodium hydroxide (Berichte, 18, 2403),
and crystallizes in bright yellow needles, melting at 74°. zw-Nitrobenzyl Alco-
hol, from »?-nitrobenzaldehyde, is a thick, yellow oil.

/-Nitrobenzyl Alcohol is obtained from its chloride and from nitrobenzyl
acetic ester. It melts at 93°.

Nitromethyl Benzene, CjHj.CHjfNOj), is obtained from nitrobenzalphtha-
lide; it is a yellow- colored liquid, boiling at 226° {Berichte, 18, 1255; ig,

1145)-

0 Amidobenzyl Alcohol, C8H^(NH2).CH2.0H, is formed by the reduction of
anlhranil and o-nitrobenzyl alcohol with zinc dust and hydrochloric acid. It
crystallizes in white needles, has an aniline odor, and melts at 82° (Berichte, 15,

2109). Benzylenimide, ^i^iCr-a '^ / ? , is the anhydride of this alcohol. It

7IO ORGANIC CHEMISTRY.

results from the reduction of o-nitrobenzyl chloride with stannous chloride. An
analogous compound is also obtained from /-nitrobenzyl chloride {BerichU, ig,
1612).

Potassium cyanate converts »-amidobenzyl alcohol into a urea, that condenses to
a benzo-metadiazine i^Berichte, 23, 2183) : —

.CH..OH -CHj.NH.

C,H / = C,H / ) + H,0.

Benzyl Sulphydrate, C5H5.CH2.SH, Benzyl Mercaptan. This is formed by
the action of alcoholic KSH upon benzyl chloride. It is a liquid, with a leek-like
odor; boils at 194°, and at 20° has a specific gravity = 1.058. Salts of the heavy
metals precipitate mercaptides from its alcoholic solutions. On exposure it
oxidizes to Benzyl disulphide, (C,Hj)2S2, which crystallizes from alcohol in
shining leaflets melting at 66°. Nascent hydrogen causes it to revert to benzyl
sulphydrate. '

Benzyl Sulphide, (CgH5.CHj)2S, is formed by the action of KjS upon an
alcoholic solution of benzyl chloride. Colorless needles, melting at 49°. Nitric
acid oxidizes it to the oxy-sulphide, (CgH5.CH2)2SO, which dissolves in hot
water and melts at 130°. The sulphone, (CgHj.CH 2)2802, melts at 150°.

Potassium BenzyJsulphonate, CjH5.CH2.SO3K + H^O, is formed on boiling
benzyl chloride with potassium sulphite. The free acid is a deliquescent crystal-
line mass ; it is isomeric with toluene-sulphonic acid.

Alcoholic ammonia converts benzyl chloride into mono-, di-, and tri-benzyl-
amines, which are separated by means of their hydrochloric acid salts. These
same compounds are obtained from benzaldehyde on boiling with formamide
(^Berickte,T.g, 2\2^; 20, 104). They result, too, when the benzothio-amides are
reduced with zinc and hydrochloric acid : —

CjH5.CS.NH, -f- 2H2 = CjH5.CH2.NH2 -f SH2.

{Berichte, 21, 51).

Benzylamine, CjH5.CH2.NH2 (Benzamine), is formed when zinc and hydro-
chloric acid act upon benzonitrile ; by the action of an alkaline bromine solution
upon phenylacetamide, CjHg.CH2.CO.NH2 (p. 160), but most readily by decom-
posing benzylacetamide, CjHj.CHj.NH.CO.CHj (from benzyl chloride with
acetamide, Berichte, ig, 1286). by means of alcoholic potash. It dissolves in
water and boils at 185°. It differs from its isomeric toluidine in being a strong
base, that attracts carbon dioxide.

tf-Nitrobenzylamine, CjH4(N02).CH2.NH2, obtained from o-nitrobenzyl-
chloride (p. 584) by the saponification of its phthalimide derivative, is a strong,
oily base {Berichte, 20, 2228). It may be reduced to o-amido-benzylamine,
CjH4(NH2).CH2.NH2 (u-benzylene-diamine). The benzene derivative of the
latter forms a quinazoline by the production of a closed ring (Berichte, 23,
2810) : —

.CHj.NH .CHj.NH

CeH4( I = CjH / I + H2O.

^NH2.C0.CeH5 ^N = C.CjHj

Dibenzylamine, (C,H,)2.NH, is an oil insoluble in water. It is formed
when PCI3 acts upon dibenzylhydroxylamine {Berichte 19, 3287).

Tribenzylamine, (C,H,)3N, forms large plates melting at 91°, and distilling
near 300° undecomposed (Berichte, ig, 1027).

CUMIN ALCOHOL. 71I

When benzyl chloride acts on aniline the products are : —

Benzylaniline, CeH^.CHj.NH.CgHs, which also results in the reduction of
benzylidene aniline with sodium in alcoholic solution. It melts at 32°, and

Dibenzylaniline, (CeH5.CH2)j.N.C5Hg, melting at 67°.

Benzyl derivatives of hydroxylamine (p. 166) {Annalen, 257, 203).

a-Benzyl-hydroxylamine, HjN.O.CjH,, is produced by decomposing
acetoxime-benzyl ether (p. 205) and a-benzaldoximebenzyl ether with hydro-
chloric acid. It is a colorless oil, boiling at 119° under 30 mm. pressure. Its
hydrochloride forms silvery leaflets, subliming above 230° without previously
melting. If it be heated with hydrochloric acid it breaks down into benzyl
chloride, hydroxylamine and ammonium chloride. Hydriodic acid converts it
into benzyl iodide and ammonia.

/?-Benzyl-hydroxylamine, C,H,.HN.OH, is obtained by decomposing ^S-ben-
zaldoximebenzyl ether (p. 718) anda/3-dibenzyl-hydroxylamine with hydrochloric
acid. It melts at 57°, dissolves somewhat in water, and reduces Fehling's solu-
tion. Its hydrochloride is very readily soluble in water and 'alcohol. It melts at
100-110° [Berichte, 22,429,613). Hydrochloric acid does not decompose it.
It yields bimolecular benzaldoxime {Berichte, 23, 1773) by oxidation.

a/SDibenzyl-hydroxylamine, C, H,.HN.O.C,H,, results upon heating a-ben-
zyl-hydroxylamine with benzyl chloride. It is a liquid. A large quantity of
water will decompose its hydrochloride. It becomes ;8-benzyl-hydroxylamine by
decomposition.

y3/?-Dibenzyl-hydroxylamine, (CjH,)2N.0H, is produced on heating hy-
droxylamine with benzyl chloride. It melts at 1 23°. Hydrochloric acid does not
decompose it.

Tribenzyl-hydroxylamine, (CjH,,) jN.O.C,Hj, results when benzyl chloride
acts upon aj3-dibenzyl-hydroxylamine (less readily if the y8/3-variety be used). It
is a liquid. Its hydrochloride is readily decomposed by water. With hydrochloric
acid it yields y8/3-dibenzyl-hydroxylamine [Berichie, 23, Ref. 402).

(2) Alcohols, CgHj„0. There are five isomerides.

Tolyl Alcohols, CeH4(CH3).CH2.0H. The ortho-hcAy (l, 2). obtained
from orthotoluyl aldehyde with sodium amalgam, melts at 31°, and boils at 210°.
(Berichte., 23, 1028). The meta, from OT-xylene bromide, CgH4(CH3).CH2Cl,
boils at 217° [^Berichte, 18, Ref. 66). The para, derived from paratoluyl aide;
hyde with potassium hydroxide, melts at 59°, and boils at 217°.

Phenyl Ethyl Alcohol, CjHs.CHj.CHj.OH, o-Tolyl alcohol, obtained
from a-toluyl aldehyde, is a liquid boiling at 212°, has a specific gravity = 1.033
at 20°, and when moderately oxidized yields a-toluic acid. Its acetic ester boils
at 224°. See Berichie, 22, 1413 for the phenylethylamines, CgHj.CjH^iNHj.

Phenyl Methyl Carbinol, CgH5.CH(OH).CH3, is a secondary alcohol, pro-
duced from ;8-brom-elhyl benzene (p. 586), and by the action of sodium amalgam
upon acetophenone, CjH5.CO.CH3. It boils at 203°. Oxidation converts it again
into acetophenone. The acetic ester boils near 214°, and partly decomposes into
acetic acid and styrol.

(3) Phenyl Propyl Alcohol, CgHs.CH^.CHj.CHj^OH), Hydrocinnamyl Al-
cohol, obtained from cinnamic alcohol, boils at 235°. It exists as cinnamic ester
in storax. Secondary Phenyl-ethyl Carbinol, CjH5.CH(OH).CH2.CHj, is
formed from phenyl-ethyl ketone, CeH..CO.C2H5, and boils at 219°.

/C H

(4) Cumin Alcohol, C5Ht<'^,^'Qjj (i, 4), contains the isopropyl-group.

712 ORGANIC CHEMISTRY.

It is formed from cuminic aldehyde. It boils at 246°, and yields common cymene,
CjoH„, when boiled with zinc dust. Its chloride, CjH,(C3H,).CH5Cl, yields the
same product, when heated with zinc and hydrochloric acid. Boiling alcoholic
potash or dilute nitric acid oxidizes it to cuminic acid. Its isomeride is tertiary —

Benzyl-dimethyl Carbinol, « ,|;jj .2 I c.qH, produced by acting on a-to-

luic chloride, CjHj.CHj.COCl, with zinc methyl. Long needles, which melt at
20-22°, and boil about 225°.

DIVALENT (DIHYDRIC) ALCOHOLS.

Dihydric £enzy!ene-G/yco/, C^li^.CH(Oil)2,-won\d correspond to methylene
glycol, but does not exist. Where it should occur, benzaldehyde appears (p. 298).
Its ethers are derived from benzylene chloride, CjHj.CHClj, through the action
of sodium alcoholates or salts of organic acids. Ihe dimethvl ether, C^Yi^.CH.
(0.0113)2, boils at 205°; the diethyl ether at 217°. The acetate, CjHj.CH
(0.021130)2, is crystalline, melts at 43°, and boils with decomposition at 220°.

Tollylene Alcohols, C^^P^ = CfiH /^^2-°^, Xylylene alcohols. The

three isomerides are obtained from the three corresponding xylylene chlorides or
bromides by boiling with a soda solution. The ortho (i, 2), called Phthalyl
alcohol, is obtained also from phthalic acid chloride by sodium amalgam. It
melts at 64°. A potassium permanganate solution oxidizes it to phthalic acid.
The meta (i, 3) melts at 46°, while \h^ para melts at 112°. The three are
readily soluble in water.

Styrolene Alcohol, C6H5.CH(OH).CH2.0H, Phenyl glycol, is obtained
from slyrolene dibromide, CgHj.CHBr.CHjBr; it crystallizes from benzine, and
benzene, in .silky needles, melts at 67-68°, and can be sublimed. It is very soluble
in water, alcohol and ether. Dilute nitric acid oxidizes it to benzoyl carbinol.

Phenyl Methyl Glycol, CgH5.CH(OH).CH(OH).CH3, exists in two modifi-
cations, a and ;8, like hydrobenzoin. These are obtained from phenyl dibrom-
propane, C5H5.CHBr.CHBr CH, (from propyl benzene). The o-body melts at
53°, the ;8- at 93° {Benchte, 17, 709).

Benzoyl Carbinol, QHs.CO.CHj.OH (Acetophenone Alco-
hol), is 2. Ketone alcohol, formed from the bromide, CeHs.CO.CHj.
Br, by its conversion into acetate, and saponification with potassium
carbonate {Berichte, 16, 1290). It crystallizes from water and
alcohol in large, brilliant leaflets, which contain water of crystalli-
zation, and melt at 73-74°. It crystallizes from ether in shining
anhydrous plates, and melts at 85-86°.

When distilled it decomposes with formation of bitter almond oil. Being a
ketone it forms crystalline compounds with primary alkaline sulphites. Like
acetyl carbinol it reduces a cold ammoniacal silver or copper solution (form-
ing benzaldehyde and benzoic acid), and is oxidized to mandelic acid (p. 321
Berichte, 14, 2100). Nitric acid oxidizes it to benzoyl-carboxylic acid, CjHj.CO.
CO2H. It yields cyanhydrin with CNH, which then forms o-phenyl glyceric
acid. Hydroxylamine converts it into the isonitroso-cottipound, C5H5.C(N.OH).
CHj.OH, melting at 70°.

It forms the hydrazone, C8H5.C(N2H.C8H5).CHjOH (melting at 112°), with
phenylhydrazine. This compound unites with a second molecule of the reagent,

OXY-EENZYL ALCOHOLS. 713

like the glucoses (p. 501), and yields the osazone, C6H5.C(N2H.C6H5)CH(N2H.
C5H5) (Berichte, 20, 822).

The a^/a/if.CgHj. CO. CHj.O.CjHjO, forms rhombic plates, melting at 49°;
the benzoaie melts at 117°; both reduce an ammoniacal silver solution, even in
the cold.

Oxy-alcohols or Phenol alcohols.

These contain, in addition to the alcoholic hydroxyl, one or
more hydroxyl groups in combination with the benzene nucleus,
hence they also possess the properties of the phenols.

(i) Oxy-benzyl alcohols, CeH^^' ^tt qtt

The ortho-compound (i, 2), Saligenin, is formed when sodium
amalgam acts upon salicylic aldehyde, or in the decomposition of
the glucoside salicin with dilute acids or ferments : —

CxaHisO, + H,0 = CjHjO, + CeH.,0,.
Salicin, Saligenin. Dextrose.

It consists of pearly tables, soluble in hot water, alcohol and ether,
melting at 82° and subliming near 100°. Lead acetate causes a
white precipitate in its solutions, and ferric chloride produces a
deep blue color in them. Dilute acids resinify it, forming saliretin,
CuH^Os. It yields salicylic acid when oxidized.

The glucosides of saligenin are salicin, f of ulin and helicin : —

Salicin. Populin, Helicin.

Salicin, CjjIIjgO,, the glucoside of saligenin, occurs in the bark and leaves of
willows and some poplars, from which it may be extracted with water. It can
be artificially prepared by reducing helicin with sodium amalgam. It forms
shining crystals, which dissolve easily in hot water and alcohol, and melt at 198°.
Its taste is bitter.

The glucoside, Populin, C20H22OJ, contained in several varieties of poplar, is
the benzoyl derivative of salicin, CjjHi ^(CjHjO)©,, and can be artificially made
by the action of benzoyl chloride, C^HjOCl, or benzoic anhydride upon salicin.
Populin crystallizes in small prisms containing 2 molecules of water, dissolves with
difficulty in water and possesses a sweet taste. Dilute hydrochloric acid decom-
poses it into benzoic acid, glucose and saliretin.

Helicin, C5H4fO.C5Hii05).CHO, is produced by oxidizing salicin with nitric
acid. It can be artificially prepared from salicylic aldehyde and acetochlorhydrose.
It dissolves with difficulty in water, crystallizes in small needles and melts at 175°;
Dilute acids and ferments break it up into salicylic aldehyde and dextrose. It
contains the CHO-group, hence combines with acetaldehyde to form glucose-
cumaraldehyde, C^n^{O.C^^^^O^\CH:ZYi..CVi.O {Berichte, 18, 1958).

Meta-oxybenzyl Alcohol, CsH4(OH).CH2.0H (i, 3), is formed from metaoxy-
benzoic acid by means of sodium amalgam. It melts at 67°, and boils at 300°.
60

714 ORGANIC CHEMISTRY.

Ferric chloride colors it violet. It is oxidized to meta-oxybenzoic acSd when fused
with KOH (but not with chromic acid, p. 686). /

Para-oxybenzyl Alcohol {l, 4) is produced by the action of sodium amalgam
(in slightly acidulated alcoholic solution) upon paraoxybenzaldehyde (dioxy-hydro-
benzoin, melting at 222°, is produced at the same time). It is readily 'soluble in
water, alcohol and ether. From benzene it crystallines in delicate needles, melting
at 110° (Berichte, ig, 2374). It melts at 197°. Its methyl ether is the so-called

Anisyl Alcohol, C6H4(O.CH3).CH2.0H (i, 4), obtained from
anisic aldehyde by alcoholic potassium hydroxide. It is but slightly
soluble in water, crystallizes in needles, melts at 25°, and boils at
259° without decomposition. It forms anisic aldehyde and acid
when oxidized.

(2) Vanillin Alcohol, C5H15O3, and Piperonyl Alcohol, CgHgOj, are formed
from their aldehydes, vanillin and piperonal, by acting on the solution with sodium
amalgam. They are derivatives of homo-pyro-catechin and creosol (p. 693), and
stand in intimate relation to proto-catechuic aldehyde. Vanillin alcohol is the
methyl-phenol ether, piperonyl alcohol the raethylene-phenol ether of protocate-
chuic alcohol, which has not yet been prepared (see vanillin) : —

fCH,(i) fCH^.OH fCH^.OH f(

J0H(3) CeH3-^O.CH3 C,H3J0\„„ ^^'^A'^

iOH(4) lOH l0/*-"2 ((

-COH
C„HjOH(3) C„H3-10.CH3 C.H,-! 0\,,„ C.Hj-j OH .

.OH

Homo-pyro- ' Vanillin Alcohol. Piperonyl Alcohol. Protocatechuic

catechin. Aldehyde.

Vanillin alcohol crystallizes in colorless prisms, melts at 115°, and dissolves easily
in hot water and alcohol. Piperonyl alcohol dissolves with difficulty in water,
forms long prisms, and melts at 51°.

TRIHYDRIC ALCOHOLS.

Phenyl Glycerol (Stycerine), CgHi^Og = CsH5.CH(0H).CH(0H).CHj.
OH, is obtained from the bromide of cinnamic alcohol, C5H5.CHBr.CHBr.CH2.
OH, by long boiling with water. It is a gummy mass, easily soluble in water and
alcohol.

■ Mesitylpne Glycerol, C5H3(CH2.0H)3, Mesicerine, is produced from tri-
brom-mesitylene, CgH3(CH2Br)3 (melting at 94°), upon boiling with water and
lead carbonate. It is a thick liquid.

ALDEHYDES.

The aldehydes of the benzene series, characterized by the group
CHO, are perfectly analogous, as regards methods of formation and
properties, with slight modifications, to those of the paraffin series.
They are distinguished as monovalent aldehydes, like :

C^Hj.CHO CjHj.CHj.CHO CeH.j(CH3)CHO, etc.

Eenzaldchyde. Phenyl-acetaldehyde. Tolylaldehyde.

ALDEHYDES. 715

and divalent or dialdehydes, like phthalic aldehyde, C6H4(CHO)2.
Aldehydes of mixed function also occur, e. g. , aldehydephenols or
oxyaldehydes, C6H4(OH).CHO, etc.

The monovalent aldehydes are obtained by the oxidation of the
corresponding primary alcohols, or by the distillation of the calcium
salts of the aromatic acids with calcium formate (p. 187). They
are derived from the benzene homologues by heating the halogen
derivatives, CsHs.CHClj, with water, especially in the presence of
bases (like sodium carbonate, lime or lead oxide), or by boiling
the mono-chlor-derivatives, QHj.CHjCl, with water, in presence
of oxidizing agents (lead nitrate).

A very interesting and direct conversion of homologous benzenes
into aldehydes, is that occurring in the action of chromyl chloride,
CrOaClj, and water (Etard).

Here the benzene homologues first unite (in CSj-solution) with two molecules of
chromyl chloride, forming brown pulverulent double compounds, e. g., CgHj.
CH3.(Cr02Cl2)2, which yield aldehydes when added to water [Berichte, 17, 1462
and 1700). All the alkylic benzenes sustain this transformation; thus, from tolu-
ene, CgHj.CHj, wejobtainbenzaldehyde, C5H5.CHO. The xylenes yield tolylalde-
hydes, and the o-haloid toluenes, yield the o-haloid benzaldehydes (Berickte, 21,
Ref. 714). With benzenes, containing higher alkyls, the reaction is more com-
plicated, as ketones are also produced, thus: propyl benzene, CjHj.CjH,, yields
benzylmethyl ketone, CeH5.CH2.CO.CH3 [Berichte, 23, 1070).

The benzaldehydes are mostly liquid bodies, which dissolve with
difficulty in water, possess an aromatic odor, and in deportment
are very similar to the fatty aldehydes. They do not reduce alka-
line copper (p. 18^), but do reduce silver solutions with the produc-
tion of a metallic mirror. They differ from the fatty aldehydes in
that they are, as a general thing, T-egdily oxidized to alcohols and
acids by alcoholic or aqueous alkalies (p. 708) ; it appears that this
reaction is, however, only peculiar to those aldehydes in which the
CHO-group is in direct union with the benzene nucleus. Further-
more, they do not directly combine with ammonia (p. 189), the
amines and hydrazines, but yield compounds with them with im-
mediate separation of water, and in the new derivatives all the
amide hydrogen is replaced by the aldehyde radicals : —

SCsH^.CHO + 2NH3 = (CeH,.CH)3N2 -f sH^O,
Hydrobenzamide.

C.H^.CHO + H2N.C3H3 == CeHj.CHiN.CeHs + H^O.

Benzylidene-Aniline.

Alcoholic potassium cyanide converts the benzaldehydes into
benzoins (see these). Again, the benzaldehydes, like all benzene
derivatives, readily furnish substitution products. An interesting
fact is their ability to afford condensation products with the most
heterogeneous bodies, water always disappearing (p. 194).

7l6 ORGANIC CHEMISTRY.

Thus, by condensation with the acids, aldehydes and ketones of the fatty series,
we obtain unsaturated acids, aldehydes and ketones, e. g. : — '

CsHs.CHiCH.COjH CjHs.CHiCH.CHO C6H5.CH:CH.CO.CH3.

C'innamic Acid. Cinnamic Aldehyde. Benzylidene Acetone.

Occasionally an aldol condensation occurs here (p. 1 95), with formation of oxy-
bodies, e.g., CjH5.CH.(OH).CH2.C02H, phenyl lactic acid> which give off water
in addition. Such a condensation follows in consequence of the action of HCl-
gas, zinc chloride, sulphuric acid and glacial acetic acid {Berichte, 14, 2460), or
upon heating with acetic anhydride. The condensing influence (especially with
acetone and acetaldehyde) of aqueous alkalies, e. g., dilute sodium hydroxide and
baryta water [Berichte, 14, 2468, and 16, 2205), is particularly interesting.

With very dilute aqueous sodium hydroxide (2%) it is possible for an aldol
condensation to occur here, whereas if the solution be alcoholic, with \o% sodium
hydroxide, "there is an immediate separation of water (Berichte, 18, 484, 720).

With malonic acid, the benzaldehydes form unsaturated dibasic acids, e.g.,
benzal-malonic acid, CeH5.CH:C(C02H)2, with acetacetic esters, acetyl carbonic

acids, e.g., benzal-acetacetic acid, CgHj.CHiC^^ „„' „ ' [Annalen, 218, 121,

and 223, 137). The benzaldehydes also condense with benzenes, phenols and

anilines, forming derivatives of triphenyl methane (€5115)3011 (see this).

MONOVALENT ALDEHYDES.

I. Benzaldehyde, QHeO = CeHs.CHO, Bitter Almond

Oil, results from the oxidation of benzyl alcohol, and by the dis-
tillation of calcium benzoate and formate. Formerly it was pre-
pared exclusively from its glucoside araygdalin ^see below). At
present it is made on a large scale from benzal chloride, CeHj. CHCI2,
with sulphuric acid, or by heating it under pressure with milk of
lime, or by boiling benzyl chloride with water and lead nitrate. It
is applied in the manufacture of benzoic and cinnamic acids, for
preparing malachite green and other coloring substances.

The bitter-almond oil, prepared from chlorinated toluene, invariably contains
chlorine ; for its purification it is advisable to change it to its sodium bisulphite
compound and then fractionate. Officinal bitter-almond oil is obtained from
amygdalin ; it usually contains hydrocyanic acid, which can be removed by shaking
it with lime and ferrous chloride.

Bitter-almond oil is a colorless liquid with a pleasant odor, and
high refractive power, and boils at 1 79° ; its specific gravity = i .050
at 15°. It is soluble in 30 parts water, and is miscible with alcohol
and ether. It shows all the reactions of the aldehydes ; when
oxidized (even in the air) it forms benzoic acid ; by reduction
(sodium amalgam) it passes into benzyl alcohol (together with hy-
drobenzoin).

AMIDE DERIVATIVES OF BENZALDEHYDE. 717

It foims crystalline compounds with the alkaline sulphites. CNH converts it
into Cyanhydrin, CjH5.CH(OH).CN (raandelic nitrile) (p. 347) — a yellow oil,
which solidifies on cooling. PCI5 converts it into benzal chloride, CgHj.CHClj
(p. 584)- Benzaldehyde dissolves in fuming sulphuric acid to form a crystalline
sulphonic acid, C6H4(CHO).S03H, which forms salts, that crystallize well
[Berichte, 16, 150).

A glucoside of benzaldehyde is Amygdalin, C^^^^'^0-^^, occurring in the
bitter almonds and in various plants, especially in the kernels of Pomacese and
Amygdalacese, and the leaves of the cherry laurel. To obtain it the bitter
almonds are freed of oil by pressing, and then digested with boiling alcohol, the
solution is concentrated and the fatty oil removed with ether. Amygdalin crys-
tallizes from alcohol in white, shining leaflets ; it tastes bitter, and dissolves readily
in water and hot alcohol. It crystallizes from water in prisms, containing 3H2O.
It yields a heptacetate when gently warmed with acetic anhydride. On boiling
with dilute acids, or upon standing with water and emuhin, a ferment present in
bitter almonds, amygdalin, is decomposed into oil of bitter almonds, dextrose and
hydrocyanic acid : —

CjoH^NOii + 2H,0 = C,HjO + iZ^^f,^ + CNH.

When amygdalin is boiled with alkalies, the nitrogen is evolved as ammonia and
amygdalic acid, CjoHjgOu, produced ; this decomposes into mandelic acid and
glucoses, when boiled with dilute acids.

Hydrogen sulphide converts benzaldehyde into three isomeric thiobenzaldehydes
(C,HgS)4 (p. 197) {Berichte, 22, 2603).

The following compound is a derivative of dihydrobenzene : —
Dihydrobenzaldehyde, CgH,.CHO. This results from a peculiar transposition
of anhydro-ecgonine {Berickte, 23, 2880). It is an oil with a suffocating odor. It
boils at 122° under a pressure of 120 mm. It exhibits all the properties of the
fatty aldehydes, and reduces permanganate, and Fehling's solution at 100°. The
oxide of silver oxidizes it to dihydrobenzoic acid.

AMIDE DERIVATIVES OF BENZALDEHYDE.

The action of ammonia upon benzaldehyde or benzyldichloride, CgHj.CHClj
(p. 715), produces Tribenzylene-diamine, CjiHijNj = (CgHj.CHjjN^, or
Hydrobenzatnide, which crystallizes from alcohol and ether in rhombic octa-
hedra, melting at 110°. It reacts neutral, and does not combine with acids; but
as a tertiary diamine it forms with ethyl iodide a Diammonium Iodide, CjjHj gNj
(CjHjIjj, which gives rise to the ammonium oxide, C^iYi-^^^'i>i2[C^'ii^^0, with
silver oxide ; this yields crystalline salts with two equivalents of the acids.

When hydrobenzamide is boiled with alcohol or acids oil of bitter almonds and
ammonia result.

Benzal-anilines are produced by heating hydrobenzamide with the anilines : —

(CeH,.CH)3N3 + sH.N.CeH, = sC.H^.CHiN.CeHs + 2NH,.

In a similar manner hydroxylaniine forms benzaldoxime [Berickte, 22, 28S7).
If heated, hydrobenzamide is transposed to amarine (-Triphenyl-dihydroglyoxaline)
(see Lophine).

The benzaldehydes combine with amines and anilines, forming benzylidene-, or
benzal-araines and -anilines (p. 715).. Acids resolve them into their components.

7l8 ORGANIC CHEMISTRY.

Benzylidene Ethylamine.CgHj.CHiN.CjH^, is an oil, boiling at 195°. Ben-
zylidene Aniline, CgH5.CH:N.CgH5, Benzal Aniline, crystallizes in yellow
needles, melting at 42°.

When benzaldehydes unite with the acid amides, e.g., CjHgO.NHj, the amid-
hydrogen is not only entirely eliminated (p. 715), but two molecules of the amides
are combined.

The aldehydine bases, resulting from the combination of benzaldehyde, with
(j-phenylene diamines, have already received mention (p. 628).

The benzaldehydes, like all aldehydes, unite with phenylhydrazine, forming
phenylhydrazones (p. 656).

Benzylidene-Phenyl-Hydrazone, CgHj.CHrN.NH.CeHs, melts at 152.5°.

Benzaldoximes.

Benzaldoxime, C8H,.CH(N0H), is formed by the action of hydroxylamine
upon benzaldehyde. It is a thick oil. Sulphuric or hydrochloric acid will trans-
form it into a crystalline isomeride, melting at 120-128° [Berichte, 23, 1684; Z2,
432). These two compounds are readily converted into each other; they are
soluble in alkalies. The sodium salt of the liquid a-aldoxime dissolves with difiS-
culty in alcohol, while that of the /?-variety is very soluble. Beckmann considers
that these isomerides differ in structure as represented in the following formulas: —

.NH
[a) CgHj.CH.-N.OH and (^8) CsHj.CH^ | .

a-Benzaldoxime. |3-Benzaldoxime.

When the sodium salts are alkylized, the a-variety yields an oxygen-ether, and
the /3-variety a nitrogen-ether : —

.N.CjHs
(a) CeH,.CH:N.O;C,H, and (/?) C,H,.CH( |

The two ethyl ethers and a-benzyl ether are oily liquids; ^-benzyl ether melts at
82°. Hydrochloric acid decomposes the a-ethers into <z-alkylhydroxylamines and
the /3-ethers into /3-alkylhydroxylamines (p. 711). Conversely, the two benzyl-
hydroxylamines convert benzaldehyde into the corresponding benzaldoxime-benzyl-
ethers. In accordance with this we find that when the a-benzyl ether is heated
with hydriodic acid the product is benzyl iodide, while the /3-ether, under similar
treatment, yields benzylamine {Berichte, 22, 1534). Ferricyanide of potassium
oxidizes o- and /3-aldoximes to azo-benzenyl peroxide, Cj^HjjNjOj, and dibenz-
enyl azoxime, Cj^Hj^NO, which also result from benzil dioximes [Berichte, 22,

1590)-

But two different Cabanilido-benzaldoximes, CsHj.CHiN.O.CO.NH.CjHj,
have been obtained by the action of phenylisocyanate upon the two benzaldox-
imes {Berichte, 22, 31 1 3). It is, therefore, concluded that the oxime groups
have similar structure : N.OH, and that the two benzaldoximes are stereochemical
isomerides (Goldschmidt, Berichte, 7,7,, 3101; Hantzsch, Berichte, 23, 15, 20;
Behrend, 23, 454). This view is confirmed by the behavior of the two anisaldox-
imes, C5H4(O.CH3).CH(N.OH), which yield, by alkylization, two different oxygen
ethers, and indeed /3-anisaldoxime forms a nitrogen ether at the same time. Hence,
there are probably three isomeric aldoximes, two stereochemical isomerides, a and
^, and a third, structurally isomeric form, called isoaldoxime (Goldschmidt, Be-
richte, 23, 2178; Behrend, Berichte, 23, 2750) : —

CJiji.CH CeH^.CH CeHj.CH,

II II I >o.

HO.N N.OH NH^

a-Aldoxime. j3-Aldoxiine. Isoaldoxime.

ORTHO-NITRO-BENZALDEHYDE. 719

The aromatic, unsymmetrical ketones, containing two different radicals, e.g.,

P^TT*>CO, also yield two ketoximes each (acetophenone- and pyroracemic-acid

form but one). From this the isomerism of the oximes is dependent upon the
asymmetry of the molecule in its relation to the nitrogen atom (Hantzsch, Berichte,
23, 2322, 2750). V. Meyer, abandoning his early views as to the cause of the
isomerism of the oximes, believes now that the same is due to the spatial con-
figuration of hydroxy! amine {^Berichte, 23, 2407).

SUBSTITUTION PRODUCTS OF BENZALDEHYDE.

The haloid benzaldehydes are obtained by substituting the nucleus of the benzyl
chlorides, CsHg.CHjCl and CgHj.CHClj. They can be prepared with less dif-
ficulty by oxidizing the haloid cinnamic acids v?ith potassium permanganate (Be-
richte, 21, Ref, 253). Benzoyl chloride, C5H5.CO.CI (p. 580), is produced when
chlorine is conducted into benzaldehyde.

NITROBENZALDEHYDES.

On dissolving benzaldehyde in nitric-sulphuric acid, or in a mixture of sulphuric
acid with nitre (calculated amount) below 30-35°, the chief product is meta-nitro-
benzaldehyde, which separates in a crystalline form. The oil (20-25 P^' cent.)
consists principally of ortho-nitrobenzaldehyde, which cannot, however, be well
obtained in pure form {Berichte, 14, 2802). o-Nitrobenzaldehyde is obtained pure
from o-nitrobenzaldoxime (see below), when it is oxidized with a chromic acid
mixture (Berichte, 14, 2334) ; also from u-nitrocinnamic ester through the action
of nitric acid and sodium nitrite (Berichte, 14, 2803). It is best obtained from 0-
nitro cinnamic acid, by oxidizing the alkaline solution with potassium permangan-
ate in the presence of benzene (Berichte, 17, 121).

Ortho - nitro - benzaldehyde, C6H4(N02).CHO, dissolves
readily in alcohol and ether, but slightly in water, from which it
crystallizes in long, yellowish needles. It melts at 46°, and distils
with scarcely any decomposition. It possesses a peculiar odor, which
is penetrating in the heat, and it distils with aqueous vapor. Potas-
sium permanganate, or chromic acid, oxidizes it to (?-nitrobenzoic
acid ; with concentrated sodium hydro}^ide (7-nitrobenzyl alcohol
and i?-nitrobenzoic acid are readily produced. Potassium cyanide
converts it into ^-azoxybenzoic acid.

(7-Nitro-benzaldehyde condenses with acetone, tinder the influ-
ence of a very little sodium hydroxide or baryta water (p. 730), to
^-nitro-phenyl-lactic-methyl-ketone, C6H4(NO0.CH(OH).CH2.CO.
CH3, which with more caustic soda immediately splits off acetic
acid and indigo {Berichte, 16, 2205) : —

2Ci„H„N0^ + 2H2O = CieHj^N^O, + aC^H.O^ + 4H2O.

720 ORGANIC CHEMISTRY.

It condenses in the same manner with acetaldehyde to o-nitro-phenyl-lactic
aldehyde, C8H4(N02).CH(OH).CH2.CHO, and o-nitrophenyl-cinnamic alde-
hyde, CgH^(N02).CH:CH.CH0. The first of these also forms indigo with the
alkalies.

With hydroxylamine, ortho-nitro-benzaldehyde yields the aldoxime, CgH^
(N02).CH(N.0H), melting at 95°. It results also from o-nitro-para-amido-
phenyl acetic acid by the action of nitrous acid, and then boiling with alcohol.
It has been called nitroso-methyl-o-nitrobenzene {Berichte, 15, 3057). Heated
with hydrochloric acid, it is split up into NH3 and o-nitrobenzoic acid; when
oxidized (ferric chloride) it forms o-nitrobenzaldehyde with evolul^n of hypo-
nitrous oxide.

The phenylhydrazine derivative, C5H4^(N02).CH(N2H.CgH5), crystallizes in
red needles, melting at 153° [Annalen, 232, 232).

Meta-nitro-benzaldehyde, CgH^(N02).CH0 (i, 3), results from the nitra-
tion of benzaldeliyde (see above). It crystallizes from water in white needles,
melting at 58°. When reduced it yields meta-amidobenzaldehyde, and when
oxidized meta-nitrobenzoic acid. PCI5 and reduction convert it into metatoluidine.
It forms two aldoximes with hydroxylamine, one melting at 63°, and the other
at 118° [Berichte, 23, 2170). The latter is identical with the so-called nitroso-
methyl-m-nitro-benzene [Berichte, 15, 838 and 3060), obtained from ?«-nitro-/-
amidophenyl acetic acid. Ferric chloride decomposes it into NjO and »j-nitro-
benzaldehyde [Berichte, 15, 2004).

PCI5 converts the aldoxime into zw-nitro-benzonitrile, C5H4(N02).CN. The
pkenylhydrazone, Q, ^'R ^(^O ^.C^A.-^ ^.Q ^^, consists of red needles, melting
at 121°.

Para-nitro-benzaldehyde, C8H4(N02).CHO (i, 4), results when ^-nitro-
benzyl chloride, CgH4(N02).CH2Cl, is boiled with water, and lead nitrate, or
when sulphuric acid acts upon /-nitrobenzal chloride, CgH^(N02).CHCl2 [Be-
richte, 16, 2539) ; finally, by the oxidation of /-nitrocinnamic acid with sulphuric
acid and nitre [Berichte, 16, 2714). It is most easily prepared by allowing
Cr02Cl2 and water to act upon /-nitro- toluene [Berichte, ig, 1061). It crystal-
lizes from water in thin prisms, and melts at 107°. Its aldoxime, C^^i^O,^.
CH(N.OH), melts at 128°, and decomposes into NHj.OH and / nitrobenzalde-
hyde [Berichte, 16, 2003), when digested with acids. Its phenylhydrazone,
C,H^(N02)-.CH(N2H.C,H5), melts at 155°.

AMIDOBENZALDEHYDES.
These are obtained by the reduction of the nitrobenzaldehydes.

Ortho-amido-benzaldehyde, C6H4(NH2).CHO (i, 2), is best
obtained by reducing ortho-nitrobenzaldehyde with ferrous sulphate
and ammonia [Berichte, 17, 456). It dissolves with difficulty in
water, from which it crystallizes in silvery leaflets, melting at 40°
to a yellowish oil. It possesses an intense odor, and volatilizes very
j-eadily in steam. It reduces an ammoniacal silver solution. Nitrous
acid converts it into salicylic aldehyde.

Its aldoxime, C8H^(NH2).CH(N.OH), results by the reduction of c-nitroben-
zaldoxime with ammonium sulphide. It melts at 133°, and when oxidized with
FeCl3, splits up into NjO and o-amido-benzaldehyde [Berichte, 15, 2004).

Ortho-amido-benzaldehyde yields condensation products with aldehydes, ketones
and acids of the fatty series (p. 710). By the withdrawal of water (and inner con-

TOLUIC ALDEHYDES. 72 1

densation) these new compounds pass into quinoline derivatives {Berichte, 16,
1833) •—

^ ^ /CH:CH.CHO_^ /CH:CH\

a-Amido-cinnamic Aldehyde, Quinoline.

CHiCH.CO.CHs .CH:CH,

C,H,( = C^H / y.CH, + 1-1,0.

<7-Amido-cinnamic Ketone. a-Methyl Quinoline.

a-Oxyquinoline (carbostyril) is produced by condensation with acetic anhydride
and sodium acetate : —

.CH:CH.CO.OH .CH:CH,

CeH / = C,H / \C.0H + H,0.

tf-Amido-cinnamic Acid. a-Oxyquinoline.

With raalonic acid it yields a-oxyquinoline carboxylic acid [Berichte, 17, 456).

Meta-amido-benzaldehyde, C|.H4^{NH2).CHO (1,3), has not been obtained
in a pure condition. It results in the reduction of ff«-nitrobenzaldehyde with stan-
nous chloride or ferrous sulphate and ammonia; also by oxidizing its aldoximewith
ferric chloride {Berichte, 15, 2044, and 16, 1997). By diazotizing it yields zw-oxy-
benzaldehyde. Its aldoxime, C5H^(NH2).CH(N.0H), is obtained by the reduc-
tion of »2-nitrobenzaldoxime with ferrous sulphate and ammonia. It melts at 88°

Para-amido-benzaldehyde, CsH^(NH2).CH0 (i, 4), is obtained from its
aldoxime through the agency of acids. It crystallizes from water in leaflets, melt-
ing at 71° ; these are not very stable. Its aldoxime, C5H4(NH2).CH(N.0H), is
produced by the reduction of/-nitrobenzaldoxime. It melts at 124-129° {Berichte,
16, 2001).

2. Toluic Aldehydes, C5H4(CH3).CHO.

These can be easily obtained from the three xylenes, CgH^(CH3)2, through the
action of CrOjClj and water (p. 715) [Berichte, 17, 1464). The ortho- and meta-
bodies resemble bitter-almond oil in odor.

o-Toluic Aldehyde results from ortho-xylyl chloride, CgH4(CH3).CH2Cl. It
boils at 200°, and readily oxidizes, on exposure to the air, to o-toluic acid.

m-Toluic Aldehyde, oh\.3xneA from meta-xylene chloride, boils at 199°, and when
exposed, soon oxidizes to m-toluic acid. When nitrated, it yields an 0 nitro-
aldehyde ; this forms methyl indigo with acetone and caustic soda.

fi-Toluic Aldehyde is obtained by the distillation of calcium paratoluate and
formate. Its odor resembles that of peppermint; it boils at 204°, and is easily
oxidized to /-toluic acid.

The so-called a-Toluic Aldehyde, CjHj.CHj.CHO, Phenylacetaldehyde,
is produced when chromyl chloride and water act upon ethyl benzene, CjH,.
CjHj ; by distillation of a-toluate of calcium and calcium formate; by heating |8-
phenyl-lactic acid or phenyl-oxy-acrylic acid with dilute sulphuric acid; from
so-called" phenyl-a-chlor-lactic acid, CsH5.CH(OH).CHCl.C02H, by the action
of sodium hydroxide (^^nV,4/?, 16, 1286); or from phenyl-o-brom-Iactic acid,
C5H5.CH(OH).CHBr.C02H, with a soda solution [Annalen, 219, 179), and,
finally, by acting with water on a-bromstyrolene. It is an oil, boiling at 206° and
yielding benzoic acid upon oxidation with nitric acid. PCI5 converts it into a-di-
chlorethyl benzene, CjHj.CHj.CHCI^ (p. 586). Nitration changes it into a com-
pound which yields indol, CjHjN, when reduced or heated with zinc dust [Be-

72 2 ORGANIC CHEMISTRY.

richte, 17, 984). By the action of chloral and AICI3 upon benzene there is
obtained the Phenyldichloracetaldehyde, CeHj.CCl^.CHO, which reduces
Fehling's and silver nitrate solutions, and oxidizes easily to the acid, CjHj.CClj.
CO2H {Berickte, 17, Ref. 229).

3. Phenyl-propyl Aldehyde, CgHj.CHj.CHj.CHOjhydrocinnamic aldehyde,
from hydrocinnamic acid, is an oil.

4. Aldehydes, C10H12O.

Cumic Aldehyde, C6H4(C3H7).CHO, Cuminol, is the iso-
propyl-benzaldehyde of the para-series. It occurs, together with
cymene, C10H14, in Roman caraway oil, and in oil of Cicuta virosa,
or water hemlock, etc. In order to effect its separation, shake the
oil, boiling above 190°, with hydric sodic sulphite, press out the
separated crystalline mass, and decompose it by distillation with
sodium carbonate. Cuminol possesses an aromatic odor, has a
specific gravity = 0.973 at 13°, and boils at 235°. Dilute nitric
acid oxidizes it to cumic acid ; chromic acid converts it into tere-
phthalic acid. When distilled with zinc dust, the isopropyl group
is transposed and ordinary cymene results.

It forms two aldoximes with hydroxylamine (^^nV,?/'^, 23, 2175). Its hydra-
zone melts at 128°.

Nitro-Cuminol, C|,H3.(N02)(C3H,).CHO, melts at 54°, and when acted upon
by PCI5, reduced, etc., yields thymol (p. 688).

Dialdehydes and Aldehyde-Alcohols (p. 324).

The aldehydes of phthalic acid, C^f{^-^^ (ortho, meta and para), correspond-
ing to the three acids, are produced (like the monovalent aldehydes) from the cor-
responding xylylene chlorides, C5H^(CHjCl)2 and C^^^QX^^ (p. S73).

fl-Phthalaldehyde is a thick oil, with an odor like that of oil of bitter almonds.
Potassium permanganate oxidizes it quite readily to phthalic acid (Berickte, 20, 509).
It combines with two molecules of hydroxylamine, yielding the di-aldoxime,
C|,Hi(CH:N.0H)2, melting at 245°.

OT-Phthalaldehyde (isophthalaldehyde) crystallizes in long needles, melting at
89-90°. It is oxidized to isophthalic acid by KMnOj (Berickte, 20, 2005, 509).
With hydroxylamine it forms a di-aldoxime, C5Hj(CH:N.OH)2, melting at 180°,
and with acetyl chloride it yields »z-dicyanbenzene, melting at 158°.

/-Phthalaldehyde (triphthalaldehyde), from/-xylylene-chloride by means of
water and lead nitrate, consists of needles, soluble with difficulty in water and melt-
ing at 115°. When oxidized it yields terephthalic acid. Ammonia converts it
into a di-imine and a hydrobenzamide derivative {Berickte, ig, 575). Potassium
cyanide changes it to benzoln-di-aldehyde (Berickte, 19, 1815). It yields a di-
aldoxime with hydroxylamine, and a diacetyl ester with acetyl chloride.

Phenyl-lactic Aldehyde, C(,H5.CH(OH).CH2 CHO, is an alcohol-aldehyde,
produced by condensing benzaldehyde with acetaldehyde by means of very dilute
soda-lye (p. 716). Acetic anhydride converts it into cinnamic aldehyde.

The three nitrobenzaldehydes similarly yield the corresponding Nitrophenyl-
lactic Aldehydes, C5H4(N©j).CH(OH).CHj CHO. The orMo-body is very

ORTHO-OXYBENZALDEHYDE. 723

unstable, and when boiled with acetic acid anhydride yields o-nitrocinnamic alde-
hyde (p. 721). The ff«^/a-compound crystallizes from ether in needles, and de-
composes about 100° {Berich/e, 18, 720). The /a?-«-compound crystallizes with
one molecule of aldehyde, which escapes at 115° [Berichte, 18, 372).

ALDEHYDE-PHENOLS OR OXY-ALDEHYDES.

The oxy-aldehydes, having hydroxyl in the benzene nucleus, are
obtained by oxidizing (p. 713) the oxy-alcohols with chromic acid.
An important synthetic method, wherein the aldehyde group is
directly introduced, consists in letting chloroform and an alkaline
hydroxide act upon phenols (reaction of Reimer) : —

C,H,.OH + CHCI3 + 4KOH = CeH./g^Q -f 3KCI + sH.O.

All the benzene oxy-derivatives (the oxyacids also) react similarly ;
hence, innumerable oxy-aldehydes have been prepared.

To perform the reaction, dissolve the phenol and some potassium or sodium
hydroxide in l J^-2 parts water, and while heating on a water bath, in connection
with a return condenser, gradually add chloroform. Chloral can be substituted for
the latter. The excess of chloroform is distilled off, the residue supersaturated
with hydrochloric or sulphuric acid, and the separated aldehyde finally extracted
with ether. Ortho-formic phenyl ether is produced at the same time (p. 671).

It is very probable the reaction proceeds in such a manner that formic acid first
results from the action of the alkali on chloroform : CHCI3 -\- 4KOH = CHO.
OK -|- 3KCI + 2H2O (p. 217) and as it is produced, acts, on the phenol. Oxy-
acids are obtained in the same way, when CCI4 '^ employed. In this reaction,
very frequently the CO^H-group, occupying the para-position in the oxy-acids
(para-oxy-benzoic acid), is exchanged for CHO {Berichte, g, 1268).

In deportment the oxyaldehydes are perfectly analogous to the
monovalent benzaldehydes. They reduce an ammoniacal silver
solution, but not the Fehling solution. Oxidizing agents convert
them with difficiilty into oxyacids ; this is most easily accomplished
by fusion with caustic alkalies. They dissolve in alkalies) forming
salts ^.^., C6H4(CHO).ONa; the alkyl iodides convert the latter
into alkyl ethers (p. 668). They give aldoximes with hydroxy 1-
amine.

I. Oxybenzaldehydes, C6H4(OH).CHO.

Ortho-oxybenzaldehyde (i, 2), Salicylic Aldehyde, oc-
curs in the volatile oils of the different varieties of Spircea. It is
obtained by the oxidation of saligenin and salicin (p. 713), but is
most readily prepared (together with para-oxybenzaldehyde) by
the action of chloroform and caustic potash upon phenol {Berichte,
10, 213). An oil, with an aromatic odor j solidifies at — 20°, and
boils at 196°; its specific gravity = 1. 172 at 15°. It volatilizes

724 ORGANIC CHEMISTRY.

readily with steam. It is rather easily soluble in water ; the solution
is colored a deep violet by ferric chloride. It colors the skin an
intense yellow. Sodium amalgam transforms it into saligenin;
oxidizing agents change it to salicylic acid : —

P „ /OH „ „ /OH p „ /OH

*-6"4\CH2.0H '-s^iXCOH "-e^^XCO.OH-

Saligenin. Salicylic Aldehyde. Salicylic Acid.

Salicylic aldehyde dissolves in caustic potash to form the crystalline derivative,
CgH^(OK)CHQ, from which ethers are obtained through the agency of alkyl
iodides. The methyl ether, C8H4(O.CH3).CHO, melts at 35°, and boils at 238°;
the ethyl ether hdCis at 248°. Salicyl aldoxime, C5H^(0H).CH(N.0H), meltsat

S7°-

Consult Berichte, :i2, 2339, upon the nitrosalicylaldehydes.

Me'ta-oxybenzaldehyde (i, 3) results together with the alcohol in the reduc-
tion of m-oxybenzoic acid with sodium amalgam, and from »«-nitrobenzaldehyde
by reduction and diazotizing [Berichte, 15, 2044). It crystallizes from hot water
in white needles, melts at 104°, and boils near to 240°. Its hydrazone melts at
131°. Its nitration produces three mononitro-compounds. A fourth ^-nitro-m-
oxybenzaldehyde has been obtained from m-nitrobenzaldehyde, and it cannot, con-
trary to statement (^Berichte, r8, 2572) be converted into vanillin.

Para-oxybenzaldehyde is formed from phenol, together with salicylic alde-
hyde; also by the reduction of para-oxybenzoic acid, and by heating anisic aldehyde
to 200° with hydrochloric acid. It is rather easily soluble in hot water, crystal-
lizes in small needles, melts at Il6°, and sublimes. Ferric chloride colors it the
same as phenol.'' It yields para-oxybenzoic acid on fusion with KOH. Its aldox-
ime melts at 65° ; its hydrazone at 1 78°. Its methyl ether is the so-called —

Anisic Aldehyde, CfiH4(O.CH3).CHO, which results in oxid-
izing various essential oils (anise, fennel, etc.) with dilute nitric
acid, or a chromic acid mixture. A soda solution will liberate it
from its crystalline 'compound with sodium bisulphite. It is a
colorless oil of specific .gravity 1.123 at 15°, and boils at 248°. It
combines with hydroxylamine to yield two aldoximes (p. 718).

2. Dioxybenzaldehydes, CjHgOg = CeH3(0H)j.CH0.

Three of the six possible isomerides have been prepared from the dioxybenzenes,
C5Hj(OH)2, by means of the chloroform reaction; likewise, six methyl dioxy-
benzaldehydes, C6H3.(O.CH3).(OH).CHO, have been obtained from the three
mono-methyl-dioxybenzenes {Berichte, 14, 2024). Dialdehydes also are simul-
taneously produced in dilute solutions when CCI3H and KOH are employed.

/3-Resorcyl Aldehyde, CjH3(OH)(OH).CHO (i, J", 4), obtained from resor-
cinol, melts at 135°, and with acetic anhydride yields (according to Perkin)
umbelliferon. Gentisin Aldehyde, C5H3(OH)(OH).CHO (l, 4, CHO), from
hydroquinone, melts at 99°; and yields gentisinic acid on oxidation.

Protocatechuic Aldehyde, QH3(0H)(0H).CH0 (i, 3, 4
— CHO in 1), the parent substance of vanillin and piperonal, was
first obtained from the latter j it is prepared synthetically from
pyrocatechin by the chloroform reaction (^Berichte, 14, 2015) ; also
by heating its ethers, vanillin, isovanillin and piperonal, with dilute

VANILLIN. 725

hydrochloric acid to 200°, and from opianic acid. It dissolves
readily in water, forms brilliant crystals (from toluene), and melts
at 150°. It reduces silver solutions with the production of a mirror,
and combines with alkaline bisulphites. Ferric chloride colors its
aqueous solution a deep green (p. 690).

Protocatechuic aldehyde is a derivative of homopyrocatechin (p.
693) ; its acid is protocatechuic acid (see this). Its important
ethers are vanillin, isovanillin and piperonal : —

fCHO (1) fCHO (I) fCHO (i)

^ iOH (4) io.CH3 (4) io/^"^ (4)

"Vanillin. Isovanillin, Piperonal.

The two OH groups in protocatechuic aldehyde occupy the ortho-position, but
the CHO group the para with reference to one of the OH groups (see proto-
catechuic acid). For the position of the methyl group in vanillin see Berichte, g,
1283, and II, 125 ; it is intimately related to creosol (p. 693).

Vanillin ,XvH803, methyl protocatechuic aldehyde, is the active
and odorous constituent of the vanilla bean pods (about two per
cent.). It was first prepared artificially from the glucoside coni-
ferine, by its oxidation with chromic acid (Tiemann), a procedure
now applied technically for the obtainment of vanillin. It is
formed synthetically, together' with aa isomeric aldehyde, wh6n
guaiacol is acted upon by chloroform and caustic alkali {Berichte,
14, 2021), and by oxidizing eugenol from clove-oil.

Glycovanillin, C5H3(O.CH,)(O.C5Hi,05).CHO, the glucoside of vanillin, is
produced when coniferine is oxidized by chromic acid. It crystallizes from dilute
alcohol in white needles, melting at 192°. Acids or emulsin split it up into
glucoses and vanillin {Berichte; li, 1595, 1657).

Vanillin crystallizes in stellate groups of needles, is soluble in
hot water, alcohol and ether, melts at 80-81°, and sublimes. As a
phenol it forms salts with one equivalentof a.base ; as an aldehyde
it combines with primary alkaline sulphites. Heated with HCl to
180° it decomposes into CH3CI and protocatechuic aldehyde. Pro-
tocatechuic acid results on fusion with potassium hydroxide (the al-
dehyde group is oxidized and methyl split off). Nascent hydrogen
converts vanillin into vanillin alcohol (p. 714) ; energetic oxidation
carries it to vanillinic acid.

Coniferine, CjjHjjOj + 2H2O, is found in the cambium of coniferous
woods, and consists of shining needles. It effloresces in the air, and melts at
185°. It acquires a dark blue color when moistened with phenol and hydro-
chloric acid. Boiling acids or emulsin decompose it into glucoses and Coniferyl

Alcohol, CioHjjOj '— C„H3 /'q^^A.CjHj.OH; the latter melts at 75°, and is
oxidized to vanillin (together with homovanillin) by chromic acid.

726 ORGANIC CHEMISTRY.

Isovanillin (see above) is obtained by oxidizing hesperilinic acid or by heating
opianic methyl ether with hydrochloric acid.

Dimethylprotocatechuic Aldehyde, Q,^^{O.CB.^^CYiO Methylvanillin, is ob-
tained from vanillin by the action of methyl iodide and potassium hydroxide. It
is not very soluble in water, melts about 20°, and boils near 285°. It yields
dimethylprotocatechuic acid by oxidation.

Piperonal, CgH^Oj, heliotropine, obtained by oxidizing piperic acid (see this)
is the methylene ether of protocatechuic aldehyde (p. 724). It consists of crystals
which dissolve with difficulty in water, melt at 37° and tjoil at 263°. Being an
aldehyde it unites with primary alkaline sulphites. When oxidized it forms
piperonylic acid, when reduced piperonyl alcohol (p. 714).

Bi-di-oxymethylene indigo is obtained from its nitro-derivative [Berichte, 23,
1566).

PCI5 converts it into the chloride, C5H3(02:CCl2)CHCl2, which yields proto-
catechuic aldehyde when boiled with water ; the group CCI2 splits off.

KETONES.

The ketones in which two benzene nuclei are joined by the
ketonic group CO, e. g., benzophenone, CsHj.CO.CeHs, will receive
attention later. At this point we will only consider the mixed
ketones, containing a benzene and also an alkyl group : —
CgH5.CO.CH3, Acetophenone.

These are perfectly analogous to the ketones of the paraffin series,
and are obtained by similar methods, chiefly by the distillation of
a mixture of calcium salts of an aromatic and a fatty acid (p. 187).
They also result when (1) sulphuric acid (diluted }^ volume) acts on
the phenylacetylenes (pp. 87 and 204) : —

CeH5.C:CH + H20 = C,H5.CO.CH3;

(2) or from the benzenes on boiling with fatty acid chlorides and
AICI3, as well as from the phenol ethers, unsaturated homologous
benzenes being formed together with the ketones {Berichte, 23,
1199):—

C5H5 + CH3.COCI = C3H5.CO.CH3 + HCl,
C5H5.O.CH3 + CHs.CO.Cl = CeH4(O.CHs).CO.CH3 + HCl;

(3) and by the decomposition of benzoyl acetic esters (p. 341) when
they are boiled with water or sulphuric acid (30 per cent.) : —

CeH5.CO.CH/^°-™3 + 2H2O =

CgHg.CO.CHj + CHj^COjH + CO^R.OH.

Benzoyl acetones (^-diketones) are produced at the same time as intermediate
products (in slight amount), e. g., CeH5.CO.CH3.CO.CH3. They dissolve in
alkalies, and are precipitated by COj. The nitro-benzoyl aceto-acetic esters
deport themselves similarly {Berichte, 16, 2239; Annalen, 221, 332). Thus
from aceto-phenone-bromide.CeHj.CO.CHjBr, we obtain bodies with aceto-acetic

PHENYL-METHYL-KETONE. 727

esters, from which, by decomposition, the y-diketones of the type CgHj.CO.CHj.
CHj.CO.CHj, are obtained ; these are insoluble in alkalies. '

y-Diketones like these are also formed by the action of succinyl chloride upon
benzenes in the presence of AICI3 ; ketonic acid chlorides are produced simul-
taneously [Berichte, 20, 1374; 21, Ref. 611) : —

CH^.COCl CHj.O.CeHj

I yields | and

CHj.COCl CHj.COCl

The benzene ketones are oils, insoluble in water, and boil with-
out decomposition ; phenyl methyl ketone is the only one that is
a solid. With the exception of benzyl-methyl ketone they do not
unite with alkaline bisulphites. , Nascent hydrogen converts them
into secondary alcohols which form ketones when oxidized.

Chromic acid transforms the ketones C5H5.COR into benzoic acid and the
alkyl, which is further oxidized (p. 203).

Cold potassium permanganate Converts a few of them into a-ketonic acids
(^Berichte, 23, Ref. 640). Acids and acid amides (Berichte, 21, 534) are formed
wheii phenylmethyl ketones are heated with yellow ammonium sulphide : —

CeH5.CO.CH3 yields CsHj.CHj.COjH and CsHj.CHj.CO.NH^.

On heating benzene ketones with concentrated or fuming sulphuric acid the
acetyl-group splits off and benzenesulphonic acids result {Berichte, ig, 2623).

The phenyl-alkyl ketones apparently form but one acetoxime with hydroxyl-
amine (p. 205) ; whereas, the unsymmetrical ketones, having two phenyl groups,
yield two acetoximes. All ketones form hydraaones with phenylhydrazine.

(i) Phenyl-methyl-ketone, CeHj.CO.CHs, Acetophenone,
results by the action of zinc methyl upon benzoyl chloride, CsHj.
COCl, and is obtained by distilling benzoate of calcium (loo parts)
with calcium acetate (56 parts). The most convenient method
consists in boiling benzene (10 parts) with acetyl chloride (i part)
and AICI3 (2 parts).

It crystallizes in large plates, melts at 20.5°, and boils at 202°-

It is applied as a hypnotic under the name of hypnone. Nascent hydrogen
converts it into phenyl-methyl carbinol (p. 711). Chromic acid and potassium per-
manganate oxidize it to benzoic acid, while a slight amount of phenyl-glyoxylic
acid {Berichte, 23, 648) is produced by ferricyanide of potassium or perman-
ganate.

Its acetoxime, C6H5.C(N.OH).CH3, melts at 59", and by the
action of concentrated sulphuric acid, or of HCl in glacial acetic
acid is converted into isomeric acetanilide : —

C5H5.C(N.OH).CH3 yields C5H5.NH.CO.CH3.

728 ORGANIC CHEMISTRY.

Other ketoximes behave in an analogous manner (transposition of
Beckmann) {Berichte, 20, 1509, 2581; 23, 2746).

The phenyl-hydrazone, CjHj.CHj.ClN.NH.CeHs, melts at 105°. Aceto-
phenone affords ^-dichlorethyl benzene with PCI5.

The chlorination of boiling acetophenone produces the so-called Acetophenone
Chloride, CjHj.CO.CHjCl, melting at 59°, and boiling at 245°. The bromide,
CgHj.CO.CHjBr, results in the action of bromine on acetophenone dissolved in
CSj (on passing COj through the solution) (^Berichte, 16, 22). It crystallizes in
large, rhombic prisms, melting at 50° ; its vapors provoke tears. The further bromi-
nation of acetophenone in carbon disulphide solution produces Acetophenone-
dibromide, CsHj.CO.CHBrj, melting at 37°; alcoholic ammonia converts it into
benzamide, CjHj.CO.NH^, and KOH changes it to mandelic acid, CeH5.CH(0H).
CO^H. With hydroxylamine, acetophenone dibromide, CgHj.CO.CHBrj, and
monobromide yield Phenylglyoxime, C5Hj;C(N.OH).CH(N.OH) (p. 207), melt-
ing at 162° {Berichte, 22, 419). Phenylhydrazine and bromacetophenone yield
the base (Ci4Hi2N2)2 (Berichte, 23, Ref. 501).

Ammonia converts the chloride or bromide into isoindol, CjgHj^Nj, identical
with diphenylpyrazine (Berichte, 21, ig, 1278).

The acid amides convert acetophenone into peculiar oxygen bases, in which, in
all probability, the oxazole ring is present (Berichte, 21, 924).

Aniline and bromacetophenone yield an anilide, which condenses to a-phenyl-
indol (Berichte, 21, 1071).

In the same manner, methyl- and dimethyl-aniline produce acetophenone-
methyl-anilide, C8H5.CO.CH2.N(CH3).CgHj ; this also condenses, yielding n-
methyl-a-phenyl indol (Berichte, 21, 2ig6, 2595) (see indol).

In the action of sodium ethylate upon a mixture of acetophenone and amyl
nitrite, a peculiar reaction (Claisen) occurs, according to the equation —

C5H5.CO.CH3 + NO.O.CjHj = C8Hj.C0.CH(N.0H) + C^H^OH,

whereby we obtain : —

Isonitroso-acetophenone, CeH5.C0.CH(N.0H). This crystallizes from
alcohol in shining prisms, melting at 127° and decomposing at 155° (Berichte, 20,
2194). It forms isoindol by reduction.

Nitro-acetophenones, C^yi^i^O^.CO.CB.^.

The meta-body is the chief product (just as in the case of benzaldehyde) when
acetophenone is dissolved in cold, fuming nitric acid. An isomeric oil is formed
at the same time. The three isomerides can be prepared from the three nitro-
benzoyl-aceto-acetic esters, which result from the action of the nitrobenzoyl chlor-
ides, C5H4(N02).C0C1, upon aceto-acetic esters (p. 726).

o-Nitro-acetophenone is a yellowish oil, of peculiar odor, and does not solidify
on cooling. Bromine converts it into a. mono- and a di-bromide, from which
indigo is obtained by the action of ammonium sulphide (Annalen, 221, 330).

m-Nitro-acetophenone crystallizes in needles, melts at 93°, volatilizes with
steam, and is oxidized to ffz-nitrobenzoic acid by potassium permanganate.

/-Nitro-acetophenone results on digesting /-nitrophenylpropiolic acid,
C5H4(N02)C;C.C02H, with sulphuric acid; it first parts with COj and the result-
ing nitrpphenyl- acetylene, C5H4(N02).C |CH, absorbs water (p. 726). /-Nitro-
acetophone forms yellowish prisms, melts at 80°, and withPCL yields ^-nitro-chlor-
styrol, CeH4(N02).CCl:CHj (Annalen, 212, 159).

Amido-acetophenones, C^'i\.^(^Yi.^.<ZO.QYi.^.

o-Amido-acetophenone (l, 2) is obtained: By reducing o-nitroacetophenone
with tin and hydrochloric acid ; from »-amido-phenyl acetylene, Cg H^(NH ^ ) C • CH,
by the action of sulphuric acid; by boiling o-amidophenyl-propiolic acid with water

BENZYL-METHYL KETONE. 729

(Berichte, 15.2153); and in slight quantity on heating acetanilide, CgHj.NH.
CO.CH3, with ZnCl^ (p. 607). It is a thiclc, yellow oil, which boils at 242°-252°,
and possesses a characteristic sweetish, lasting odor. A pine splinter, dipped into
the aqueous solution of its hydrochloride, is colored an intense orange-red. It is
very stable, and cannot form an inner condensation product. Acetic anhydride
converts it into the acetate, C6H^(NH.CjH30).CO.CH3; the bromides of the lat-
ter yield indigo when shaken with sodium hydroxide and air (Berichte, 17, 963).

»!-Amido-acetophenone results on reducing w-nitro-acetophenone. It con-
sists of yellow crystals, melting at 93°. /-Amido-acetophenone is obtained by
reducing the/-nitro body, and also on boiling aniline with acetic anhydride and
ZnCl^ (Berichte, 18, 2688). It crystallizes in flat needles, and melts at 106°.

Oxyacetophenones, or Ketophenols.

These are produced when di- and tri-hydric phenols are heated with glacial
acetic acid and ZnClj to 160° {Berichte, 23, Ref. 43).

a-Naphthol reacts in a similar manner [Berichte, 21, 322). Ethers of ketophe-
nols are produced by the action of phenol ether upon acid chlorides in the presence
of AlClj (p. 726). Alkyl benzenes are simultaneously produced (Berichte, 23,
1 199). Propionyl chloride converts phenol into phenol propionic esters and pro-
pionyl phenol, C^Yi^{O:).C.fi^.0Yi. [Berichte, 22, Ref. 746).

Resacetophenone, CgH3(OH)j.CO.CH3, from resorcinol, melts at 142°, and
may be obtained by fiising ^-methyl umbelliferon with potassium hydroxide.-
Quinacetophenone, CjH3(OH)2.CO.CH3, from hydroquinone, melts at 202°.
Gallacetophenone, C6H2(OH)3.CO.CH3, from pyrogallic acid, melts at 168°.

(2) Phenyl-ethyl Ketone, CgHj.CO.CjHj, propiophenone, results when a
mixture of calcium benzoate and propionate is distilled, or when zinc ethyl acts
upon benzoyl chloride, CgHj.COCl, and by the action of AICI3 upon benzene and
propionyl chloride. It boils at 208-210°. Nascent hydrogen converts it into sec-
ondary phenyl-propyl alcohol (p. 711); chromic acid breaks it up into benzoic
and acetic acids. Amyl nitrite converts it into phenyl-isonitroso-ethyl ketone,
CeH5.CO.C(N.OH).CH3, melting at 109° {Berichte, 22, 529).

Phenyl-propyl Ketone, CgHg.CO.CgHj, obtained from calcium benzoate
and butyrate, boils at 220-222°. Chromic acid decomposes it into benzoic and
propionic acids. The isomeric Phenylisopropyl Ketone, C5Hg.CO.C3H,,
from calcium benzoate and isobutyrate, boils at 21 5°, and is converted into benzoic,
acetic and carbonic acids by chromic acid.

Phenylketones of the higher alkyls, Uke CgH5.CO.C4H9 and CeH5.CO.C5Hn,
have been prepared from mono- and di-alkylic benzoyl acetic esters, C3H5.CO.
CHR.COjR and CjHj.CO.CR^.COjR (p. 726) by a ketone decomposition in-
duced by alcoholic potash.

3. Benzyl-methyl Ketone, C^^.di^.COSZYi.^, Phenyl acetone, results in
the distillation of calcium alphatoluate and acetate, and when zinc methyl acts on
alphatoluic chloride, CgHj.CHj.COCl. It boils at 214-216°, unites with primary
sodium sulphite, and decomposes with chromic acid into benzoic and acetic acids.
When its nitro-ptodact is treated with zinc dust and ammonia an amido-derivative
of the ortho series is first formed — C8H4(NH2).CH2.CO.CH3, but this loses
water and becomes methyl ketol : —

CsH^^NlElf °'^"' = CeH^/g^H^CCH, + Ufi.
Methyl Ketol.
61

73© ORGANIC CHEMISTRY.

Benzyl-ethyl Ketone, CgHj.CHj.CO.C^Hj, results from n-toluic chloride by
the action of zinc ethyl. It boils at 226°, and is oxidized by cliromic acid to
benzoic and propionic acids.

Phenyl-ethyl-methyl Ketone, CsH^.CHj.CHj.CO.CHj, Benzyl acetone, is
formed from calcium hydro-cinnamate and acetate, and from benzyl aceto-acetic
ester (p. 340). It boils at 235°, and when the nitro product is reduced conden-
sation ensues in the ortho-amido-derivative first produced, with formation of
hydromethyl quinoline, CjdHjgN : —

.CH,.CH,.C0.CH3 .CHj.CH,.

C,H / = C,H / ):C.CH,.

Hydromethyl Quinoline.

An oxy-derivative of phenyl-ethyl-methyl ketone is Phenyl-lactic acid — Methyl
Ketone, C5H5.CH(OH).CH2.CO.CH3. The ortho- and para-nitroderivatives of
the latter are obtained by the condensation of ortho- and paranitrobenzaldehyde
by means of very dilute sodium hydroxide (p. 723).

»-Nitrophenyl-lactic acid-Methyl Ketone forms large crystals, melting at
69°. When acted upon by excess of sodium hydroxide, or when boiled with
water, it at once (by the union of two molecules and the elimination of two mole-
cules of acetic acid) yields indigo (Baeyer, Berichte, 15, 2857) : —

2CeH,/^^J°^)-^^^-^°-^^=' = qeHi„N,0, + 2CH3.C0,H 4- 2H,0.

Indigo.

When heated with acetic anhydride it splits off water and becomes o-nitroben-
zylidene acetone, C|5H^(N02).CH:CH'.CO.CH3.

p-Nitrophenyl-lactic acid-Methyl Ketone.,^ from ^-nitrobenzaldehyde, melts at
58°, and when boiled with acetic anhydride yields /-nitrobenzylidene acetone
{Berichte, 16, 1968).

4. Methyl ketones of the homologous benzenes are readily obtained by the
action of acetyl chloride or acetic anhydride upon benzenes in the presence of
AICI3 (p. 726).

f-Tolyl-methyl-kelone,C^'R^{QM^.CO.Q.Yi^, acetyl toluene, is obtained from
cymene by the action of concentrated nitric acid (p. 577). It is a colorless liquid,
boiling at 224°. Nitric acid oxidizes it to paratoluic acid and chromic acid to
terephthalic acid. See Berichte, 21, 2265, for higher tolylalkyl ketones.

Xylylmethyl Ketones, €5113(0113)2. CO. CH3 : The ortho (from orthoxylene)
boils at 243°, the meta at 228°, and ihe. para at 224°.

See p. 518 for phenyl trimethylene ketone, CjHs.CO.CH/SS^X^or benzoyl
trimethylene. X'-^a/

Keton-aldehydes or Aldehyde Ketones (p. 323).

Benzoyl Formic Aldehyde, C5H5.CO.CHO, phenyl glyoxal, is obtained from
isonitroso-acetophenone, C5H5.CO.CH(NOH) p. 728). It crystallizes from water
as a hydrate, melting at 73°. It volatilizes in a current of steam and provokes
sneezing (Berichte, 22, 2557). Phenylhydrazine converts it into a hydrazone and
an osazone. Alkalies convert it into mandelic acid, CgH5.CH(OH).C02H.

Toluyl Formic Aldehyde, CgH^(CH3).C0.CH0, from isonitrosotolylmethyl
ketone, also crystallizes as a hydrate, melting about 100°.

Benzoylaldehyde, CjHj.CO.CHj.CHO, is a /3-ketone aldehyde. It is ob-
tained by the condensation of acetophenone and formic ester by means of sodium
ethylate (Claisen, p. 323): CjH5.CO.CH3 + CHO.O.CjH^ = C3H5.CO.CH2.
CHO -|- CjHj.OH. The sodium compound first forms, and from this acetic acid

it

MIXED TRIKETONES. 73 1

liberates the aldehyde ketone, as a yellow, very unstable oil. It resembles the
P ketonaldehydes of the fatty series very much, and is colored an intense red
by ferric chloride. It condenses with phenyl-hydrazine to diphenyl-pyrazole
{Berichte, 2i, 1135).

Diketones (see p. 325).

a- or Orthodiketones, CgHj.CO.CO.R, are produced by replacing the isonitroso-
group of the isonitroso ketones (p. 325).

Benzoyl Acetyl, CgH^.CO.CO.CH^, from isonitroso-ethyl-phenyl ketone,
C5H5.CO.C(N.OH).CH2 (p. 73b), is a yellow oil with a peculiar odor {Berichie,
21, 2176; 22, 527).

The /3- or meta-diketones, CgHj.CO.CHj.CO.R, result from the decomposition
of the benzoyl-acetoacetic esters (p. 726) ; further by a remarkable condensation,
induced by sodium alcoholate (Claisen, Berichte, 20, 2178). Thus, benzoyl
acetone is obtained from benzoic ester and acetone, and from acetophenone and
acetic ester : —

CeH5.CO.O.Ci,H5 + CHj.CO.CHj = CeHjCO.CHj.CO.CHj -f C^H^.OH.
CjH5.CO.CH3 + CH3.CO.OR = C5H5CO.CH2.CO.CH3 + C2H5.OH.

Ketonic acids are similarly produced (see these) ; while the formation of benzoyl
aldehyde from acetophenone and formic ester (see below), and that of isonitroso-
phenone are analogous (p. 728).

The /3-diketones behave like the /3-diketones of the fatty series. They dissolve
in alkalies. This distinguishes them from the other diketones. They are colored
an intense red by ferric chloride. They form pyrazole compounds with phenyl
hydrazine.

Benzoyl Acetone, CgH5.CO.CH2.CO.CH3 (see above), acetyl acetophenone,
is most readily prepared by the action of acetic ester and sodium ethylate upon
acetophenone (Berichie, 20, 2180). It melts at 60-61°, boils at 260-262°, and
readily volatilizes with steam. It forms an oxime. anhydride, Cj^HgNO (Berichte,
21, 1150) with hydroxylamine. Alkyl derivatives have not been prepared.
o-Nitrobenzoyl Acetone, C5Hj(N02).CO.CH2.CO.CH3, from o-nitrobenzoyl
acetic ester, melts at 55°.

Propionyl acetophenone, CgHj.CO.CHj.CO.CjHj, etc., have been prepared
in an analogous manner by the condensation of acetophenone with higher fatty
acid esters (Berichte, 20, 2181).

Phenyl-acetyl-acetone,CiiHi202 = C6H5.CH2.CO.CH5,.CO.CH3, results
from the decomposition of phenyl acetyl-acetoacetic ester, CSH5.CH2CO.

Cn/pQ-S^s (from CjH5.CH2.COCl and acetoacetic ester). It is an oil boihng

about 268°. It yields a pyrazole derivative with phenylhydrazine (Berichte, 18,

2137).

The following is a 7-diketone (p. 328) : —

Acetophenone-acetone, C6H5.CO.CH2.CH2.CO.CH3, is obtained from
acetophenone aceto-acetic ester (p. 727). It is a yellow oil, insoluble in alkalies,
and not volatile with aqueous vapor (Berichte, 17, 2756).

Being a y-diketone it can split off water and yield phenylmethylfurfurane.
P2S5 converts it into phenylmethylthiophene, while ammonia changes it to phenyl-
methyl pyrrol (p. 329).

The analogous ketones: diphenacyl, dibenzoyi methane, and tribenzoyl me-
thane, will be discussed under the compounds containing several benzene nuclei.

Mixed Triketones : Dibenzoyi Acetone, (CgH5.CQ)jCH.CO.CH3, from sodium
benzoyl acetone and benzoyl chloride, melts at 102°. The hydrogen of its CH-

732 ORGANIC CHEMISTRY.

group cannot be replaced by sodium or alkyls {Berichte, 21, 1153). Triacetyl
Benzene, C5H3(CO.CH3)3(l, 3, 5), results from the condensation of acetalde-
hyde. It melts at 163°. It may be oxidized to trimesic acid {^Berichte, 21, 1145).

CO.CH2.CO.CsH5
Oxalyl-diacetophenone, I (.S^rzV/i^.?, 21, Ii34),is a tetraketone.

CO.CH,.CO.C.H,

NITRILES.

The nitriles of the benzene series, the compounds of the benzene
nucleus with the cyanogen group, are formed, like the fatty nitriles,
by distilling the alkali benzene sulphonates with potassium cyanide
or yellow prussiate of potash (p. 659), and by the action of PjOj
or PCI5 upon the ammonium salts and amides of the aromatic acids
(p. 282).

When the halogene benzene sulphonic acids are distilled with CNK the halogen
atoms are also replaced by cyanogen groups and we get dicyanides : —

C^H^Br-SOsK + 2CNK = C5H^(CN)j + SO3K, + BrK.

The direct replacement of the halogens in the benzene hydrocarbons is of excep-
tional occurrence, e. g., when chlor- and brom-benzene are conducted over strongly
ignited potassium ferrocyanide, or when benzene iodide is heated to 300° with
silver cyanide, the product being cyan-benzene.

Further, the nitriles of both the benzene and the paraffin series are formed when
acetyl chloride or anhydride acts on the aldoximes : —

CjH^.CHiN.OH =.CeH5.CN + H^O.

The methods of formation peculiar to the benzonitriles are : —

1. The distillation of aromatic acids with potassium sulphocyanide, or what is
better, with lead sulphocyanide (^Berichte, 17, 1766) : —

aCeH^.COjH + (CNS)2Pb = 2C6H5.CN + PbS + 2CO2 + H^S.

2. To heat the phenyl mustard oils with copper, free of cuprous oxide, or with
ziac dust : —

CeHj.NiCS + Cu = C^H^-CN + CuS.

The mustard oils can be easily obtained from the anilines, and in this manner
there occurs a successive conversion of the anilines into nitriles and acids (p.

613)-

When the diphenylthiureas (p. 616) are heated with zinc dust, both nitriles and
anilines are produced (Berichte, 15, 2508) : —

CS(NH.C,H,), -f Zn = CgHj.CN + C.H^.NH, + ZnS.

n of the formanilides (p. 606) with concer
ist (Berichte, 17, 73) : —

CeHj.NH.CHO = CeH^.CN + H^O.

3. The distillation of the formanilides (p. 606) with concentrated hydrochloric
acid or with zinc dust (Berichte, 17, 73) : —

BENZONITRILE. 733

Both reactions generally yield but a small outcome, inasmuch as decompositions
usually result {Berichte, 18, looi).

4. The distillation of the triphenyl phosphates (p. 670) with potassium cyanide
or ferrocyanide [Berichte, 16, 1771) : —

PO(O.C,H,)3 + 3KCN = PO(OK)3 + 3CeH,.CN.

5. The transformation of the isomeric nitriles or carbylamines (p. 613) through
the agency of strong heat : —

CjHj.NC yields CeH5.CN.

6. The transformation of diazochlorides upon heating them with potassium
cyanide and copper sulphate : —

CgHs-NjCl + CNK = C5H5.CN + KCl + N^.

In this way the three nitroanilines, after conversion into diazochlorides, have
been changed to the corresponding nitrobenzene nitriles, C5H4(N02).CN.

The benzonitriles are similar to those of the fatty series, and like
them, when acted upon by alkalies or acids, form the corresponding
aromatic acids. Nascent hydrogen (better sodium in alcoholic
solution, p. 283) converts them into amines. They combine with
alcohols and HCl, with hydroxylamine and with anilines, to form
HCl-imido-ethers, oximido-ethers and benzenyl amidines (p. 735).

Benzonitrile, CsHj.CN, Cyanbenzene, is isomeric with phenyl
carbylamine, CeHj.NC (p. 613), and is best obtained from benzene
sulphonic acid, by distillation with potassium cyanide, or by dis-
tilling benzoic acid with lead sulphocyanide {Berichte, 17, 2767).
It is an oil with an odor resembling that of oil of bitter-almond^,
and boils at 191°; its specific gravity = 1.023 ^*^ °°- Like all
nitriles it unites with the halogens, the halogen hydrides, and
hydrogen. Acids and alkalies saponify it to benzoic acid.

5«i5jft'/afe</ benzonitriles have been obtained from the substituted benzamines.

The nitrobenzonitriles, C ^'^ i^i^O ^.C^ , are obtained from the three nitro-ani-
hnes by diazotizing and then boiling with potassium. cyanide and copper sulphate
(see above). The chief product in the nitration of benzonitrile is ffz-nitrobenzoni-
trile, melting at 115-117°. The ortho melts at 109°, and the/o;'« at 147°. When
saponified with sodium hydroxide, they yield the three nitrobenzoic acids.

Polymeric nitriles, or tricyanides, derivatives of hypothetical cyanuric acid,
C5N3H3 (p. 285), containing one alkyl and two phenyl groups, are produced when
AlCig acts upon a mixture of benzonitriles and the nitriles of fatty acids {Berichte,
22, 803). The hydrogen tricyanide, C3N3H3 (p. 285), which is their basis, is a
" six-membered ring," containing three C-atoms and four N-atoms. It may be
considered an analogue of the pyridine, C5H5N, and pyrimidine, C^H^Nj, rings,
each of which contain nitrogen. The derivatives of tricyanogen are, however,
more easily decomposed into ammonia and the constituent acids than the last-
named compounds.

734 ORGANIC CHEMISTRY.

Methyldiphenyl Tricyanide, C3N3(C5H5)j.CH3, from benzonitrile with acetyl
chloride and AICI3, melts at 110°. It forms salts with one equivalent of acids.
Ethyldiphenyl Tricyanide, C3N3(CgH5)2.C2H5, from benzonitrile and propionyl
chloride, melts at 67°.

Diphenyl Tricyan Carboxylic Acid, C3N3(C5H5)2.C02H, is formed when
methyl-diphenyl cyanide is oxidized with potassium permanganate. It melts at
1 92°, when it decomposes into COj and diphenyl tricyanogeahydride,C3H3(C3H5)jH,
melting at 75° {Berichte, 23, 2382).

Triphenyl Tricyanide, (CsH5;CN)3^C2iHi5N3, Cyanphenine, is formed
by polymerization of benzonitrile on dissolving H^in fuming sulphuric acid, or boil-
ing it with sodium, as well as by the action of sodium upon a mixture of cyanuric
chloride and benzene iodide {JBerichie 20, Ref. 102 ; 22, 1760), and upon heating
benzylidene-benzamidine, C5H5.C(NH).N:CH.CgH5 (p. 736) beyond its point of
fusion. It is said to be most readily obtained from- benzimido ether (p. 735) (^Be-
richte, 22, 161 1). Cyanphenine is almost insoluble in water, alcohol and ether,
readily soluble in carbon disulphide, and crystallizes in needles, melting at 231°.
Nascent hydrogen converts it into ammonia and lophine, CjjHj jNj. It is decom-
posed into ammonia and benzoic acid when it is heated with hydriodic acid.

(2) Cyantoluenes, CpH4('^j^^,Tolunitriles. The three isomerides result from

the three corresponding toluidines by their conversion into mustard oils, and then
heating with copper (see above), or more easily by boiling their diazo-derivatives
with potassium cyanide and copper sulphate. The ortho- and para-bodies are also
obtained from the toluene sulphonic acids. The ortho boils at 204° (Berichte, 19,
756); the w«^a has not yet been prepared in pure form; the /ara crystallizes in
needles, melts at 28.5°, and boils at 218°. They change to the corresponding
toluic acids when saponified.

o-Cyanbenzyl Chloride, C3Hj(CN).CH2Cl, formed by the chlorination of
o-cyantoluene, melts at 61°, and boils at 252° {Berichte, 20, 2223). Aceto-acetic
ester or malonic ester converts it into o-cyanbenzyl acetic ester. If the latter be
saponified with hydrochloric acid, it will part with carbon dioxide and change to
hydrindone( Berichte, 22, 2019 ; 23, 2479) : —

CsH.<^H,.CH,CO,R+^lJ^O = CeH /^° >CH,-^ R.OH+CO, +NH3.

/-Cyanbenzyl Chloride, CgH4(CN).CH2Cl, from /-cyanbenzyl toluene, melts
at 79°, and boils at 263°. Potassium cyanide converts it into/-cyanbenzyl cyanide,
which yields homoterephthalic acid (Berichte, 22, 3208; 23, 1059).

(3) Benzyl Cyanide, CgHj.CHj.CN, is isomeric with the cyan-toluenes. This
is the chief ingredient of several cresses, and is artificially prepared from benzyl
chloride, CjHj.CHjCl, with potassium cyanide (Berichte, 19, 1950). It boils at
229°, and yields toluic acid by saponification;

The hydrogen of the CHj-group, combined with the negative groups, CgHj and
CN, is very readily replaced (Berichte, 20, 534 ; 21, 1291). Nitrous acid, acting
upon a sodium-ethylate solution of benzyl cyanide, produces isonitrosobenzyl cyan-
ide, CgHs.CIN.OHj.CN, melting at 129° It dissolves with a yellow color in the
alkalies. It forms isonitrosophenylacetic acid by saponification (Berichte, 22, Ref.
200). Sodium ethylate, acting upon benzyl cyanide and aldehydes, produces con-
densation products, e.g., benzaldehyde yields a-phenyl-cinnamic nitrile, CgHj.
C{CH.C8H5)CN. Anisic aldehyde, furfurol, etc., react similarly. The alkyhc
benzyl cyanides are not capable of yielding such products (Berichte, 21, 356; 22,
Ref. 199).

One hydrogen atom of the CHj-group can be replaced by alkyls when sodium
ethylate and alkyl iodides act upon benzyl cyanide. Powdered caustic soda is

BENZIMIDO-ETHYL ETHER. 755

frequently substituted for the sodium ethylate {Berichte, 21, 1291 ; 21, Ref. 197).
In the resulting mono-alkylic benzyl cyanides, CjHg.CHR.CN, the ease with
which the second H-atom can be replaced will be dependent upon the molecular
magnitude and the negative character of the first substituent (Berichte, 22, 1238;
23, 2070).

The nitration of benzyl cyanide affords chiefly /-Nitrobenzyl cyanide, CjH^
(N02).CH2.CN, and slight quantities of the o- and m-bodies (Berichte, 17, 505) ;
the latter can also be made from 0- and ?«-nitrobenzalcohol by means of the chlor-
ide (Berichte, 19, 2636). The ortho crystallizes in needles from hot water and
melts at 83°. The meta melts at (^1°, and the para at 1 14°. Alcoholic soda dis-
solves the ortho with a violet color, the para with a carmine red color, forming
salts of the alkali metals, in which the metal may be replaced by radicals (Berichte,
21, 2477; 22, 327). Diazobenzene chloride and the para compound yield an
azo- and a hydrazo-derivative. They yield condensation products with the alde-
hydes (Berichte, 23, 3133). The Amidobenzyl Cyanides, C5H^(NH2).CH2.
CN, result from the reduction of the nitrobenzyl cyanides with tin and hydrochloric
acid. When diazotized, the para- and meta-compounds yield oxybenzyl cyan-
ides, C6H<.(0H).CHj.CN, which further form oxyphenyl acetic acids, C^^(OY{.).
CHg.COgH.

(4) Dicyaiibenzenes, CgH^(CN)2, result from the three brombenzene sulpho-
nic acids, and on distilling the benzene-disulphonic acids with potassium cyanide.
The »2«/a-^0i^ (also obtained from isophthalamide), melts at 156°; the para- at 220°;
the former yields isophthalic and the latter terephthalic acid.

(5) Tolyl Cyanides, C6H^(CH3).CH2.CN. The three isomerides have been
obtained from the three xylenes by means of the tolyl bromides, CgHj(CHg).CH2Br.
The CHj-group in these compounds can be readily replaced (Berichte, 21, 1331).

(6) Xylylene Cyanides, C5H^(CH2.CN)2, have been obtained from the cor-
responding bromides. Bo'th CHj-groups in them are easily substituted (Berichte,
21, 72, 2318).

In this connection may be mentioned the imidoethers and oximido-ethers, also
the benzenylaviidines and benzenyloxaviidines.

The imido-ethers (their HCI-salts) result from the action of HCl upon a mixture
of a benzonitrile with an alcohol (p. 292) : —

C,H,.CN + C3H5.OH + HCl = C,H,.C^NH.^^C1

All cyanides react in a like manner (Berichte, 21, 2650), with the exception of
those in which an ortho-position, relatively to cyanogen, is replaced by a C-group ;
therefore, in the case of the o-dicyanides, only one cyanogen group reacts (Be-
richte, 23, 2917). Water decomposes the HCl-imido-ethers into acid esters and
ammonium chloride. For the action of secondary amines, consult Berichte, 23,
2927.

Benzimido-Ethyl Ether, CgH5.C(NH).O.C2H5, is formed by the action of
ethyl iodide upon silver benzamide. Its hydrochloric acid salt consists of large,
shining prisms, and at 120° decomposes into benzamide and ethyl chloride. The
free ether, separated by alcoholic ammonia, is a thiclc oil, which decomposes when
heated or when standing into alcohol and cyanphenine.

The oximido ethers, or acidoximes result when hydroxylamine acts on the
imido-ethers (p. 292) : —

CeH,.C^NH^^^ + H2N(OH).HCl = C,H,.c(^N.OH ^ ^ ^^^^^

736 ORGANIC CHEMISTRY.

Benzoximido-ether, CgH5.C(N.OH).O.C2H5, is a liquid, dissolving in ether,
and solidifying to a crystalline mass. It is identical with the so-called Ethyl-
benzo-hydroxamic Acid (Berichte, 17, 1587), obtained from benzoyl chloride
and hydroxylamine.

The benzenylamidines, or benzamidines, correspond perfectly to the amidines of
the paraffin series (p. 293), also to the ethenyl-diphenyl-amidines, and the phenylene-
amidines or anhydro bases (p. 627).

Phenylcyanate (p. 613) converts the amidines into diureides, e. g.,
P „ p/N.CO.NH.CeHj
""s^s-^XNH.CO.NH.CgHs

(Berichte, 23, 2923), while if phenyl mustard oil be employed the products will
be amidine thioureas, CgH5.C(NH).NH.CS.NH.CjH5 (Berichte, 22, 1609).
Acid anhydrides convert them into acidyl amidines, e. g., benzoyl benzamidine,
CgH5.C(NH)NH.C0. CgHj (Berichte, 0,1, 1605). The amidines combine with al-
dehydes io alkylidene amidines, e. g.,benzylidene amidine, C5H5.C(NH).N:CH.
C5H5 (Berichte, 22, l6lo; 23, 2924). j8-Ketonic esters, as acetoacetic esters, etc.,
cause the amidines to condense to oxypyrimidines. Succino-succinic ester pro-
duces keto-quinazolines (Berichte, 23, 2623). See Berichte, 23, 2934 for the action
of aromatic a-oxycarboxylic acids.

Benzenylamidine, CjHj.C^^tt , Benzamidine. Its hydrochloride is formed

when alcoholic ammonia acts upon HCl-benzimido-butyl ether fp. 292.) It con-
sists of large vitreous crystals containing two molecules of water and melts at 72°.
When anhydrous it melts at 169° (Berichte, 22, 1607). The free benzenylamidine,
separated by sodium hydroxide, is crystalline,, melts at 75-80°, and at higher
temperatures breaks up into 3NH3 and cyanphenine. Benzylidene Benzamidine
(see above) melts at 152°, and readily yields cyanphenine. Nitrous acid converts
it into the dinitroso-compound, C7H5.N2H(NO)2. Phenylbenzenylamidine,

CgHj.C^^j^jT p TT , results from benzonitrile or thiobenzamide, CgH5.CS.NHj,

when heated with aniline hydrochloride (p. 293). It melts at 112°, and when dis-
tilled yields benzonitrile and aniline. Symmetrical Diphenyl-benzenyl-amidine,
C5H5.C(N.C(.H5).NH.CjH5, obtained from benzanilide, CeH5.CO.NH.C5H5, or
benzotrichloride, CJH5.CCI3, by means of aniline hydrochloride, melts at 144°.
Unsymmetrical C8H5.C(NH).N(C5H5)j, from benzonitrile and diphenylamine,
melts at 111° (Annalen, 192, 4).

The Oxamidines or Amidoximes are produced : I, by the action of hydroxyl-
amine hydrochloride upon the benzenylamidines : —

<^6"6-C(nH, + H,N(0H).HC1 = C5H5.C^JJgH) + NH.Cl;

2, by the action of the same reagent upon the imido-ethers, when the ammonium
chloride very likely acts on the oximido-ethers first formed (Berichte, 17, 1588 and
1694) :—

CeH5C<Sg| + NH,C1 = C,H5.C(^^0«).HC1 + C,H5.0H;

3, from the nitriles and thioamides by direct union with hydroxylamine (Berichte,
19, 1669):—

CeH5.CN + H,N(OH) = CeH5.C^^gH)

CeH5.CS.NH, -f H,N(OH) = CeH5.C^N.0H ^ jj^g

Ferric chloride imparts a deep red color to the alcoholic solution of the amidoximes.

ACIDS. 737

Benzenylamidoxime, CjHb.C:^^^ ) {Berichte, i8, 1053), crystallizes

from ether in large plates, and melts at 79-80°. It gives the isonitrile reaction
with chloroform and potassium hydroxide. Nitrous acid changes it to benzamide,
CgHj.CO.NHj. With acids and caustic alkalies it yields salts, e.g., C-H..
C(N.0H)NH2.HC1 and C^YL^.a:^Yi..^)-:ii.OY^. Alkylic iodides convert the
latter into amidoxime-ethers, e.g., C5H5.C(NH2):N(O.C2H5), which nitrous acid

changes to ethers of benzhydroxiniic acid, CjHg.C^j^S^ •'. "YK^mixnx^Berichte,

18, 727) considers these ethers different from those of benzhydroxamic acid
(p. 746) while according to Lessen they are identical (Berichte, 22, Ref. 588).

The amidoximes condense with the aldehydes to hydrazoximes [Berichte, 22,
2412, 3140) :—

CsH^.C^g^J^ + CHO.CH3 = C,H,.C^N^)CH.CH3.

Ethylidene Benzenyl-
hydrazoxiine.

Azoximes, ,:.g., benzenylazoxime, CgHj.Cl^ij ^C.R {Berichte, 22, 2758;

ig, 1475), result from the action of chlorides or anhydrides of organic acids upon
the amidoximes : —

CeH^.C^iJJ^^^ + CH3.COCI = CeH^.C^^-O^CCH, + H,0 + HCl.

Ethenyl Benzenylazoxime.

They are also produced by the. oxidation of the hydrazoximes (see above).

ACIDS.

The aromatic acids are derived by replacing hydrogen in the
benzenes by carboxyls : —

>-6"5-'-U2"- ^e^^lcOjH ^s^HCOaH

Benzoic Acid. Toluic Acids. Xylic Acids.

CgPifj.CHg.COgH Cgrig.CHg.CHg.COgH.

Alphatoluic Acid or Hydrocinnamic or

Phenylacetic Acid. S-Phenylpropionic Acid.

CeH.j^g^^g C,H3(CO,H)3 CeH,(CO,H), C^CCO^H),.

Benzene Dicarboxylic Benzene Tricarboxylic Benzene Tetracarboxylic Mellitic
Acids. Acids. Acids. Acid.

The important general methods of forming the aromatic acids
are : —

I. The oxidation of the hydrocarbons with a chromic acid mix-
ture, potassium permanganate or dilute nitric acid. The side-chains
are directly converted, by chromic acid, into CO^H ; the hydrocar-
bons, CeHs.CHj, CeHj.CjHs, C6H5.C3H7, etc., all yield benzoic
acid, CeHj.COjH. With nitric acid it is sometimes possible to
oxidize only the most extreme carbon atom of the side-chain.
62

738 ORGANIC CHEMISTRY.

Should several side-chains chance to be present, chromic acid will
almost invariably oxidize them all directly to CO2H. Thus, the
xylenes, QH4(CH3)2, yield dicarboxylic acids, QHj (COjH)^.

Dilute nitric acid forms mono-carboxylic acids, e.g., CeH^^ mSr'
and potassium permanganate produces both varieties. ^ *

Only ihtpara- and meta-derivatives (the former more readily than the latter)
of benzenes, carrying two side-chains (the xylenes and toluic acids), are oxidized
to acids by chromic acid, while the ortho- are either not attacked at all or are
completely destroyed. Nitric acid, or better, potassium permanganate, oxidizes all
(even the ortho- derivatives) to their corresponding acids. The haloid toluenes
(p. 584), the nitro-toluenes (p. 590), and toluene sulphonic acids (p. 665) deport
themselves similarly. The same is observed with dialkyl benzenes, where the
entrance of a negative group hinders the oxidation of the alkyl occupying the
ortho- place {Berichte, 15, 1022).

In the homologous phenols the OH-group completely prevents the oxidation of
the alkyls by the oxidizing agents mentioned ; this is true, too, in all the isomer-
ides; but it does occur in a peculiar manner, if the phenyl hydrogen be replaced
by alkylic groups or acid radicals (p. 686).

In the derivatives with two different alkyls {e. g., cymene, C5H^(CH3).(C3.H,),
the higher alkyl is usually attacked first, by nitric acid or chromic acid (or CrOj-
CI2), and converted into carboxyl [Berichte, 11,619); while in the animal organism
the methyl group suffers oxidation {Berichte, 16, 619). Sometimes, however, the
methyl group is first oxidized ; this occurs when dilute nitric acid is the oxidizing
agent [Berichte, ig, 1728). Potassium permanganate occasions at first an entrance
of OH in the propyl group, accompanied often by a transposition (p. 346 and
Berichte, 14, 1 1 35).

Potassium ferricyanide oxidizes methyl to carboxyl, if the nitro-group occupies
the ortho position relatively to the methyl group. This does not occur if the nitro-
group holds the meta-position [Berichte, 22, Ref. 201, £01).

In oxidizing the benzenes with chromic acid it is customary to employ a mix-
ture of CrjOjKj (2 parts) with sulphuric acid (3 parts), which is diluted with 2-3
volumes of HjO, and apply it in the quantity necessary for oxidation (CrjO,Kj
yields 3O and oxidizes 1CH3). The mixing is performed in a flask provided with
a long upright tube, the whole boiled for some time, until all the chromic acid is
reduced and the solution has acquired a pure green color. The product is dilu-
ted with water, the solid acid filtered off and purified by dissolving in soda, etc.
Soluble acids are extracted with ether; the volatile acids are distilled over with
steam.

When oxidizing with nitric acid, use acid diluted with 3 parts of water and boil
for some time, in connection with a return condenser (2-3 days). To remove the
nitro-acids which are invariably formed, the crude product is digested with tin
and concentrated hydrochloric acid; this converts the nitro- into amido-acids,
which dissolve in hydrochloric acid.

Potassium permanganate often effects the oxidation at ordinary temperatures.
The substance or (with acids) its alkaline solution, is shaken with an excess of
permanganate; hydrated manganese dioxide separates, while the potassium salt
of the acid produced passes into the solution.

ACIDS. 739

2. Oxidation of the aromatic aldehydes and alcohols.

3. The conversion of the nitriles (p. 211) when boiled with
alkalies or acids : —

CjH5.CN + 2HjO = CjHj.CO^H + NH3,
CeHs.CH^.CN + 2B.fi = C.Hj.CHj.CO.H + NH3.

Hydrochloric acid changes the oxychlorides (obtained from the aldehydes and
ketones with CNH) to oxy-acids (p. 347J. Sometimes in this case chlorinated
acids first form, and are converted into oxy-acids by boiling with alkalies (see
Mandelic acid).

4. Action of sodium and CO2 upon mono-brombenzenes —
Kekule : —

CsH.Br.CH, + CO, + 2Na = CeH./^gs^^ + NaBr.

The phenols react directly with CO, and sodium, forming oxy-
acids — Kolbe : —

CeH^.ONa + CO, = C,H /g^^^^

Instead of letting sodium and carbon dioxide act on the free phenols, it is better
to expose the alkaline phenates to heat, in a current of C02-gas (see Salicylic
Acid). If the CO, should act further above 300°, oxyisophthalic acid and oxy-
trimesic acid will result. In the substituted phenols (their ethers) the halogen
atom is replaced by the carboxyl-group : —

CjHiBr.O.CHg + CO, + 2Na = C6H4(O.CH3).C02Na + NaBr.

The dioxyphenols of the meta-series (resorcinol, orcinol) can be changed to
dioxyacids when heated with ammonium carbonate or potassium (sodium) dicar-
bonate and water to 130°, or even by merely boiling them [Berichte, 18, 3202 ;

'~ CeH,(0H), + CO, = CeH3(OH),.CO,H.

5. A similar reaction is that of sodium and esters of chlorcarbonic
acid upon phenols and brom-hydrocarbons — Wurtz : —

C.H^Br + C1C0,.C,H5 + 2Na = C5H5.CO,.C,H5 + Na,(BrCl),
QH^.OK + C1C0,.C,H5= C,H /gj^(.^jj^ + KCl.

6. The action of phosgene gas upon benzene in the presence of
AICI3 (p. 569) ; at first acid chlorides are produced, and these
change further into benzene-ketones : —

CjHj + COCI, = CeHj.COCl + HCl.

Similarly, phosgene and esters of chloroxalic acid act directly upon dimethyl
aniline (p. 601).

Ethyl urea chloride, in the presence of AICI3, acts in an analogous manner upon

740 ORGANIC CHEMISTRY.

benzenes — the products then are derivatives of aromatic acids {Berichte, 20,
120) : —

CeH, + C1.C0.NH.C,H5 = CjH^.CO.NH.C^Hs + HCl ;
Etnylbenzamide.

urea chloride, Cl.CO.NH^ (p. 376) behaves similarly {Beriehte, 21, Ref. 294) :—

CeHj + Cl.CO.NHj = QHj.CO.NHj + HCl;
Benzamide,

while diphenylurea chloride (CeH5)j.N.C0.Cl (p. 611) [Berichte, 20, 2n8) and
phenylisocyanate (carbanile) {Berichte, 18, 873, 2338) may be included in the
same category : —

CeHj + CO.N.CeHj = CeH^.CO.NH. C^U^.

A modification of the urea chloride process consists in the action of nascent cyanic
acid, CONH, the benzene or phenol ether being heated with cyanuric acid
(C0NH)3 and AICI3 {Berichte, 23, 1190) :—

CjHe + CONH = CeHj.CO.NHj.

Eenzamide.

7. Fusion of salts of sulphonic acids of the hydrocarbons, or of
the aromatic acids with sodium formate : —

CeH<^§^^^: + CHNaO, = C,H /^O^Na ^ s03HNa.

8. By heating the halogen nitro-derivatives of the hydrocarbons
with potassium cyanide and alcohol, to 200-230° in sealed tubes : —

. CeH^^NO, + ^^^ = ^6H*\CN + NO.K.

The nitrile immediately becomes an acid. In this reaction the cyanogen group
displaces NO,, but does not assume the same position in the benzene nucleus
{Berichte, 8, 1418). In the same manner, when alcoholic potassium cyanide acts
upon m- and /-dinitrobenzene one nitre group is replaced by CN, while an oxy-
alijil growp enters at the same time.

9. Action of benzyl chloride upon ethers of sodium acetoacetic
ester, and the decomposition of the ketonic esters, formed at first,
by alkalies (p. 212). Benzyl malonic acid, C6H6.CH2.CH(C02H)2,
is similarly formed from sodium malonic ester ; it loses CO2 and be-
comes benzyl acetic acid, QHs.CHj.CHj.COjH (p. 212).

10. Action of sodium upon the benzyl esters of the fatty acids ;
here, too, esters are produced at first : —

CHg CHg.CHg.CgHg

2 I + Na = I + CH..CO„Na + H,

CO.O.CHj.CjHj C0.0.CHj.C,H5

Benzyl Acetic Ester. Benzyl Phenylpropionic Ester.

ACIDS. 741

but subsequently they yield saturated and unsaturated acids {An-
nalen, 193, 321, and 204, 200) : —

I yields | and I

CHj.CHj.CO^.CjH, CH2.CH2.COjH CH:CH.CO,H.

Phenylpropionic Ester. Phenylpropionic Acid. Phenylacrylic Acid.

Phenyl butyric and phenyl crotonic acids are similarly obtained from the benzyl
propionic esters.

11. The direct syntheses of aromatic acids from, parafHn com-
pounds have been given upon pp. 565, 566.

12. The special synthetic methods for oxy-acids and ketonic acids,
as well as for the unsaturated acids, are described under these gen-
eral headings.

The aromatic acids occur naturally, partly iii a free state, partly
in many resins and balsams, and in the animal organism (hippuric
acid, tyrosine). They arise also in the decay of albuminoid bodies
{Berichte, 16, 2313).

The aromatic acids are crystalline solids, which generally sub-
lime undecomposed. Most of them dissolve with difficulty in water,
hence are precipitated from their salt solutions by mineral acids.
Sodium amalgam or zinc dust will reduce some to aldehydes, and
heating with concentrated hydriodic acid or phosphonium ioidide
converts them into hydrocarbons. When heated with lime or
soda-lime, their carboxyl-groups are eliminated and hydrocarbons
result : —

^eH*{ COjH = C6H5.CH3 + CO3,
Ce(CO,H)e = CeH, + 6CO2.

From the polycarboxylic acids we obtain, as intermediate pro-
difcts, acids having fewer carboxyl-groups, e.g., phthalic acid first
yields benzoic acid and then benzene : —

CeH.CCOjH), = CeH^.COjH and C,H,.

The hydrogen of the benzene nucleus in the acids can sustain
substitutions similar to those observed with the hydrocarbons and
phenols. In other respects they are very similar to the fatty acids,
and afford corresponding derivatives.

742 ORGANIC CHEMISTRY.

MONOBASIC ACIDS.

Benzoic Acid, C^HeOj = CsHs.COjH, occurs free in some
resins, chiefly in gum benzoin (from Styrax benzoin), and in coal tar
{Berichte i8, 615) ; as hippuric acid in the urine of herbivorous
animals. In addition to the general synthetic methods it is ob-
tained from benzotrichloride, CeHj.CCls, when heated with water to
150°, or by mixing with sulphuric acid; also by boiling benzyl
chloride, CeHs-CHjCl, with dilute nitric acid, or by acting on ben-
zene with carbon dioxide in the presence of aluminium chloride.

Preparation. — Gum benzoin is sublimed in an iron pan, covered with a paper
cone. Or the powdered resin is boiled with milk of lime, lime water (to decolorize
the dye stuflFs) added to the filtered solution of the lime salt, and the benzoic acid
precipitated with hydrochloric acid. A more advantageous method is the pro-
duction of the acid from hippuric acid (benzoyl glycocoll, p. 744). To accom-
plish this, boil the latter for an hour with 4 parts of concentrated hydrochloric
acid, and filter off the separated benzoic acid. Benzoic acid results from phthalic
acid by heating its calcium salt to 300-350° (see above) with I molecule of cal-
cium hydroxide.

Benzoic acid crystallizes in white, shining needles or leaflets,
melts at 120°, and distils at 250°. It volatilizes readily, and is
carried over with steam. It dissolves with difficulty in cold water
(i part in 600 parts), but readily when heated. The vapors possess
a peculiar odor, which produces coughing.

The acid yields benzene and carbon dioxide when heated with
lime ; with excess of the latter benzophenone also results. Sodium
amalgam converts it into benzaldehyde, hydrobenzoin and hydro-
benzoic acid, C,Hi(|02.

The benzoates are mostly quite readily soluble in water. Ferric chloride throws
out a reddish precipitate of ferric benzoate from their neutral solutions.

■'The potassium salt, 2C,H5KOj -|- HjO, crystallizes in concentrically grouped
needles. The calcium salt, (C,H502)2Ca -f- sH^O, consists of shining prisms or
needles. The silver salt, C,H5Ag02, crystallizes from hot water in bright leaflets.
The esters of benzoic acid, as well as those of all other aromatic acids, are pre-
pared by conducting hydrochloric acid into an alcoholic solution of the acid, and
are aromatic-smelling liquids. They can also be obtained by shaking benzoyl
chloride with alcohols and sodium hydroxide, until a permanent alkaline reaction
is observed (Berichte, 19, 3218). The methyl ester, C,H50j.CH3, boils at 199°,
the ethyl ester at 213°, the isoamyl ester at 261°. The isopropyl ester boils about
218° and decomposes into benzoic acid and propylene. The benxylic ester,
CgHj.CO.O.CjH,, occurs in Peru- and Tolu-balsam,* and is formed when ben-
zyl chloride acts upon benzal alcohol. It also results from the interaction of
sodium or potassium ethylate and glacial acetic acid upon benzaldehyde (benzyl

* Peru- and Tolu- balsams are thick, yellow-brown liquids, which are obtained
from the bark of varieties of Myroxylon. In addition to resins and some free
benzoic and cinnamic acids they also contain benzyl-benzoic and cinnamic esters
(Cinnamein).

MONOBASIC ACIDS. 743

alcohol and methyl benzoic ester are also produced) [Berichte, 20, 647). It
crystallizes in needles, melts at 21°, and boils at 324°. The phenyl ester,
CgH^.CO.O.CgHj, is formed from benzoyl chloride and phenol, or by fusing
benzoic acid with phenol and POCI3 (p. 668); it melts at 66°.

Dihydrobenzoic Acid, C,Hj02 ^ CjH^.CO^H, may be prepared by
oxidizing dihydrobenzaldehyde with argentic oxide {Berickte, 23, 2886). It does
not dissolve in water as readily as benzoic acid. It volatilizes with steam, and
when cooled solidifies to a feathery crystalline mass, melting at 95°. It has an
odor resembling that of cinnamon, and it reduces ammoniacal silver solutions.

Hexahydrobenzoic Acid, CyHjjOj = CjHjj.COOH, Hexanaphthene Car-
boxylic Acid. This occurs together with associated acids in the petrolic acids of
petroleum. It is isolated by the fractional distillation of the methyl esters (5,?-
richte, 23, 870). It is a viscid oil, boiling at 215-217°. Its odor resembles that
of baldrianic acid.

Benzoyl Chloride, CgHj.COCl, results when benzoic acid is distilled with
PCI 5, and when chlorine acts upon boiling benzaldehyde. It is an oil with a
penetrating odor. It boils at 199°, and is slowly converted into benzoic acid by
water. Excess of PCI5 converts it into benzotrichloride, CjHj.CClj. Benzoyl
bromide, from benzoic acid with PBrj, boils at 217°— 220°.

Benzoyl Cyanide, CgHj.CO CN, is produced when benzoyl chloride is dis-
tilled with potassium or mercury cyanide. It crystallizes in large tables which
melt at 34° and boil at 208°. When boiled with alkalies it changes to benzoic
acid and potassium cyanide ; concentrated hydrochloric acid converts it into ben-
zoyl-formic acid. When phenylhydrazine acts upon benzoyl cyanide hydrocyanic
acid is evolved and a-benzoyl phenylhydrazine results. Nitrobenzoyl cyanide
(Berichte, 22, 329) reacts in a similar manner.

Benzoic Anhydride, (C,H50)jO, is obtained by heating dry sodium ben-
zoate (6 parts) to 130° with PCI3O (l part), or upon digesting benzoyl chloride
with lead nitrate [Berichte, 17, 1282). It consists of prisms insoluble in water,
melts at 42°, and boils at 360°. It changes to the acid on boiling with water.
Benzoyl Peroxide, (C^^^^O^^O^t for™s large crystals, melts at 100° and defla-
grates.

Thiobenzoic Acid, C5H5.CO.SH, results when benzoyl chloride acts upon
alcoholic potassium sulphide. It is crystalline, melts at 24° and distils in aqueous
vapor. Its ethyl ester boils at 243°. When its ethereal solution is exposed to the
air the acid rapidly changes to Benzoyl disulphide, (C, 1150)282 ; brilliant crystals,
which melt at 128°. Benzoyl sulphide, (CjH50)2S, is obtained when benzoyl
chloride acts upon thiobenzoic acid. It crystallizes from ether in large prisms,
melts at 48° and decomposes when distilled.

Dithiobenzoic Acid, CgH5.CS.SH, is obtained when CgHj.CClj is boiled
with alcoholic potassiuln sulphide; CgHjCCl, + 2K2S = CgHgCS^K + 3KCI.
The free acid is very unstable. The lead salt crystallizes from carbon disulphide
in red needles.

Amide Derivatives of Benzoic Acid.

Benzamide, CjHg.CO.NHj, results when benzoyl chloride or benzoic ester
acts upon alcoholic ammonia. It is best obtained by heating benzoic acid and
ammonium thiocyanate to 170°. It crystallizes in pearly leaflets, melts at 130°,
and boils near 288°. It is readily soluble in hot water, alcohol and ether.

744 ORGANIC CHEMISTRY.

It combines with hydrochloric acid to C,H,ON.HCI. When it is boiled with mer-
curic oxide we obtain the crystalline compound CjHj.CO.NHg. Silver benza-
mide, CgH5.CO.NHAg or C5H5.C(NH).O.Ag, obtained by precipitating the
aqueous solution of benzamide and silver nitrate with sodium hydroxide, is a
brown precipitate. When digested with ethyl iodide it yields benzimido-ethyl
ether, CeH5.C(NH).O.C2H5 (p. 735-) {Berichte, 23, 105, 1550). Consult Berichte,
23, 3039 for sodium benzamide.

Methylene-dibenzamide, CHj(NH.C0.CgH5)j, is identical with the so-
called hipparaffin obtained in the oxidation of hippuric acid with PbOj and
nitric acid, and results from benzonitrile and methylene dimethylate. It melts at
233° and when heated with water is decomposed into benzamide and formalde-
hyde.

Dibenzamide, (C,H50)2NH, results from the action of sulphuric acid upon
benzonitrile. It melts at 148° and dissolves in sodium hydroxide to the salt
(C,H50),N.Na.

Thiobenzamide, CgHj.CS.NHj, is formed when hydrogen sulphide is con-
ducted into an ammoniacal, alcoholic solution of benzonitrile (p. 260). It melts
at 116°. Hydrochloric acid and zinc convert it into henzylamine [BericAie 21,
53). Thiobenzanilide, CgH5.CS.NH.C5H5, may be obtained from phenyl-
benzenylamidine by the action of hydrogen sulphide or carbon disulphide. It
forms yellow plates, melting at 98°.

On mixing aniline and benzoyl chloride we get Benzanilide, CjHj.CO.
NH.C5H5, Phenyl-benzamide, which can also be made by the action of alumi-
nium chloride (p. 727) upon benzene and carbanile, and upon heating diphenyl-
ketoxime, {CgH5)jC:N.0H, whereby a molecular transposition is brought about.
It crystallizes from alcohol in leaflets, melts at 158-160°, and distils without de-
composition. PCI5 converts it into benzanilide-imidechloride, CjHj.CChN.
CjHj (p. 258), which can also be obtained from diphenyl-ketoxime (CgHj)^
C:N.OH, by a transposition of the chloride [Berichie, 19, 992 ; 20, 504) : —

(CeH5)jC:NCl yields CgHj.CChN.CsHj.

From benzene the imidechloride crystallizes in large leaflets, melting at 40°, and
boiling at 310°. Water or alcohol resolves it into hydrochloric acid and benzani-
hde.

Benzanilide-imidechloride, acting upon aceto-acetic ester or malonic ester, pro-
duces compounds like CgH5.N:C(C5H5).CH('p„2„, anil-benzenyl-malonic

ester, which, when heated, eliminate alcohol, and by the closing-up of the ring
yield quinoline derivatives [Berichte, ig, 1462).

Benzoyl Toluidines, CjHj.CO.NH.CgH^.CHj, are similarly prSduced from
the three toluidines with benzoyl chloride, and with PCI5 yield the corresponding
imidechlorides, C5H5.CC1;N.C,H,, which, upon further condensation with ma-
lonic esters, yield quinoline derivatives (Just, Berichte, 19, 979 and 1541).

Hippuric Acid, Benzoyl glycocoll, C9H9NO3 =

CHj. pQTT , occurs in consideraDle amount in the urine

of herbivorous animals, sometimes in that of man. Benzoic acid,
cinnamic acid, toluene and other aromatic substances, when taken
internally, are eliminated as hippuric acid. It can be obtained
artificially by heating benzamide with monochloracetic acid : —

CjHj.CO.NHj + CH2CI.CO2H = CsH5.CO.NH.CHj.COjH + HCl,

MONOBASIC ACIDS. 745

by the action of benzoyl chloride on silver glycocollide {Berichie,
15, 2741), or by adding sodium hydroxide to glycocoll and shak-
ing with benzoyl chloride (Berichte, 19, Ref. 307), and by heating
benzoic anhydride with glycocoll {Berichte, 17, 1662).

To prepare it boil the urine of horses with milk of lime, filter, concentrate the
solution, and precipitate with hydrochloric acid. To purify the crude acid digest
it with chlorine water, or dissolve it in dilute sodium hydroxide, add sodium
hypochlorite, boil to decolorization, and then precipitate the cold solution with
hydrochloric acid.

Hippuric acid crystallizes in rhombic prisms, and dissolves in 600
parts cold, and readily in hot water and alcohol. It melts at 187°,
and about 240° decomposes into benzoic acid, benzonitrile and
prussic acid. Phosphorus pentachloride converts it into isoquino-
line, while its ethyl ester yields Hippuroflavin, C9H5.NO2 {Be-
richte, 21, 3321).

Its silver salt, CgHjAgNOj, crystallizes from water in silky needles. The
ethyl ester is best obtained by digesting glycocoll ester with benzoic anhydride ;
it is crystalline, melts at 60°, and decomposes when distilled.

Boiling acids or alkalies decompose hippuric acid into benzoic acid and glyco-

coll. Nitrous acid converts it into benzoyl glycollic Acid, CHjCf „q '„ ^ ,

which crystallizes in fine needles. It is easily soluble in hot water, is monobasic,
and yields salts which are readily soluble. ConsViXt Berichte, 22, Ref. 551, for
the condensation products obtained from hippuric acid and the aldehydes.

Potassium chlorate and hydrochloric acid produce chlorinated hippuric acids.
«-Nitrohippuric acid, C5H8(N02)N03, is obtained by adding hippuric acid to a
mixture of nitric and sulphuric acids. It forms shining prisms, which are not
very soluble in water, and melt about 150°. When boiled with acids it breaks up
into glycocoll and m-nitrobenzoic acid (p. 747)-

Benzoyl Hydrazine, CgHj.CO.NH.NHj, is a derivative of diamide, N^Hj
(p. 166). It may be prepared by the action of hydrazine upon benzoyl glycollic
ester (Berichte, 23, 3023). It crystallizes in large leaflets, melting at 112°.
Sodium nitrite and acetic acid convert in into Benzoyl Azimide, CgHj.CO.NiNj
(p. 640), which by boiling with sodium hydroxide, is converted into benzoic acid
and the sodium salt of azoimide or hydrazoic acid, HN3.

Benzhydroxamic Acids (p. 260).

These acids are produced in the same manner as the analogous acids of the
fatty series from the acid chlorides, esters and amides, by the action of hydroxyl-
amine {Berichte, 22, 2856, 3070; Ref. 587) (see Berichte, 22, 1270) :—

CeH,.CO.O.C,H, + NH,.OH = C.H,.C^gj^H + C,H,.OH,

CeHs.CO.NH,+ NH,.OH = CeH,.C^^^^+ NH3.

When these are heated with phenylhydrazine the oxime-group is eliminated and
oxyhydrazones result {Berichte, 22, 3070) : —

C,H..C(OH).(N.OH) + NH,.NH.C„H5 =
° \^ CeHj.qOH) (N.NH.CjHs) + HjN.OH.

746 ORGANIC CHEMISTRY.

Benzhydroxamic Acid, CgHj-C^Q^ , is very soluble in hot water. It

•crystallizes in leaflets and plates, melting at 125° {Berichte, 12, 1272).
Two isomeric ethers are derived from it by the introduction of alkyls : —

Alkyl Benzhydroxamic Ether. Alkyl-benzhydroxamic Acid,

The first result when alkyl iodides and caustic alkali act upon benzhydroxamic
acid. They are identical with the benzhydroximic acids obtained from benzenyl-
amidoxime by alkylization and the subsequent action of nitrous acid (Lessen,
Berichte, 22, 588). Acids resolve them into benzoic acid and a- hydroxy lamine
ethers, HjN.OR (p. 166).

The second class are produced when the benzoyl group is introduced into benz-
hydroxamic acid and the product further alkylized, etc. They are identical with
the benzoximido-ethers prepared from benzimido-ether. When the ethyl derivative
is digested with hydrochloric acid it forms ethyl chloride and benzhydroxamic acid
[Berichte, 22, Ref. 588). The benzhydroxamic ethers and ethylbenzhydroxamic
acid yield the same ethyl benzhydroxamic ethylate, C5H5.C.(N.O.C2H5).O.C2H5.

Substituted Benzoic Acids.

These are formed by the direct substitution of benzoic acid or
by oxidizing substituted toluenes. The action of the halogens (or
of hydrochloric acid and potassium chlorate ; of bleaching lime and
of antimony chloride) upon benzoic acid is not as energetic as
upon the hydrocarbons ; the mono-substitution products of the meta
series (p. 589) are almost the sole products. In the action of nitric
acid small quantities of ortho- and para- compounds also result.
The mono-substituted toluenes of the meta and para series are
readily oxidized by chromic acid to the corresponding substituted
benzoic acids, whereas the ortho-derivatives are attacked with
difficulty and then completely decomposed (p. 738). However,
the ortho-compounds are oxidized to the corresponding benzoic
acids by dilute nitric acid, or by an excess of potassium perman-
ganate. Thus (i, 2)-brom-, iodo- and nitro-toluene yield (i, 2)-
brom-, iodo- and nitrobenzoic acids. Furthermore, substituted
benzoic acids can be obtained from the oxy-acids by PCI5 and also
from the amido-benzoic acids (by forming the diazo-compound and
boiling with the haloid acids). When the halogen nitrobenzenes
are heated with potassium cyanide substituted benzoic acids are the
products. The ortho- melt at the lowest temperatures, are rather
readily soluble in water, and yield easily soluble barium salts,
whereby they can usually be quite readily separated from the meta-
and para-derivatives. When they are fused with caustic potash
oxy-acids result.

Monochlorbenzoic Acids, CjH^Cl.COjH. The ortho (i, 2)-body was
formerly called chlorsalicylic acid.and may be obtained from salicylic acid, C5H4
(0H).C02H, by the action of PCI5 ; the chloride, CeH^Cl.CO.Cl, formed at first,
boils at 240° and is decomposed by boiling water. It sublimes in needles, melting

MONOBASIC ACID^. . .^m 747

at 137° (they melt below 100° in water). Thfey can aBo be^HEeaqrort (l, 3)-
chlornitrobenzene by the action of potassium cyanide. Mea^lorhenzoic Acid
(1,3) is produced by oxidizing (l, 3)-chlortoluene, and from benzoic"^ acid by
boiling it with hydrochloric acid and CIO3K, with HCl and MnO^, with bleaching
lime or with SbCl^ ; also from chlorhippuric acid, and from (i, 4)-chlornitroben-
zene with potassium cyanide. It sublimes in flat needles, melting at 153°. Para-
chlorbenzoic Acid (l, 4), called chlordracrylic acid, is obtained from (I, 4)-chlor-
toluene; it sublimes in scales, and melts at 240°.

Monobrom>enzoic Acids, CsH^Br.COjH. The ortho-acid, from ortho-
bromtoluene (with nitric acid) and from orthoamidobenzoic acid (on heating the
perbromide of the diazo-compound with alcohol), sublimes in needles and melts
at 147-148°; its barium salt is very soluble in water. The common metabrom-
benzoic acid, obtained from (i, 3)-bromtoluene, and by heating benzoic acid and
bromine to 120-130° (with some l, 2-brombenzoic acid), sublimes in needles,
melting at I55°- ('> ^-Brombenzoic Acid, from parabromtoluene, is almost
insoluble in water, crystallizes in needles, and melts at 251°-

Monoiodo-benzoic Acids, CgH^I.CC^H. The ortho-zx.\& from ortho-iodo-
toluene (by means of nitric acid) and ortho-amidobenzoic (by decomposition of
the diazo-compound with hydriodic acid) forms needles and melts at 159°. It
yields salicylic acid with caustic potash. Metaiodobenzoic Acid (1, 3), from meta-
iodo-toluene and meta araidobenzoic acid, sublimes in needles, and melts at 187°;
(l, 3)-oxybenzoic acid results when it is fused with caustic potash. Paraiodo-
benzoic Acid (i, 4), from paraiodo-toluene, paraiodo-propyl benzene, para-amido-
benzoic acid and/-amidoacetophenone, crystallizes from alcohol in pearly leaflets,
sublimes in scales and melts at 265°- When fused with potassium hydroxide it
yields paraoxybenzoic acid.

Fluorbenzoic Acids, CnH4Fl.CO.jH. These are obtained by boiling the
three diazoamido-benzoic acids with hydrofluoric acid. The ortho-acid melts at
Il8°,the meta-acid 3X 124°, and ^ht para-acid ai. l8i° (Berichte, 15, 1197). They
separate out in urine as fluorhippuric acids. Di-Jluor-benzoic Acid,C^}ii^\.CO^'R,
from benzoic acid and Cr2Flg,is in external properties very similar to benzoic acid.
It melts at 232°.

Nitrobenzoic Adds, C6H4(N02).C02H.

Metanitrobenzoic acid is the principal product in the nitration of
benzoic acid. The quantity of the ortho (20 per cent.) and para
(1.8 per cent.) acids is less.

Preparation. — Gradually add sulphuric acid (4 parts) to a mixture of fused and
pulverized benzoic acid (\ part) with nitre (2 parts) and apply heat to the mass
until it melts, then pour the fused acids off' from the potassium sulphate. To effect
their separation convert them into barium salts and recrystallize ; the barium salt
of the meta-acid dissolves with great difficulty {Annalen, 193, 202). In the nitra-
tion of cinnamic acid p- and (7-nitro-cinnamic acids are formed. The oxidation of
these yields the corresponding nitrobenzoic acids. The nitration of hippuric acid
gives rise to a nitrohippuric acid, which yields metanitrobenzoic acid. The nitro-
benzoic acids can also be prepared by oxidizing the three nitrotoluenes (p. 746),
and ortho- and para-nitrobenzyl chloride (p. 584) with potassium permanganate;
further, by converting the three nitroanilines into three nitrobenzonitriles and saponi-
fying the latter with alkalies (p. 634) (Berichte, 18, 1492). The ortho-nad. is
most easily prepared by oxidizing o-nitrotoluene with potassium permanganate
{Berichte, 12, 443) and the /anz-acid by oxidizing /-nitrotoluene with a chromic
acid mixture.

748 • ^ ORGANIC CHEMISTRY.

(i, 2)-NuroSmmic Acid crystallizes in needles or prisms, melts at 147°, pos-
sesses a sweet t^re and dissolves in 164 parts of water at 16°. In the action of
PCI5 upon it there is formed, in addition to o-nitrobenzoyl chloride, the anhydride
of o-nitrobenzoicacid, (C6H4(N02)CO)20, melting at 135° {Berichte, 17, 2789).
The ordinary (i, ■^-nitrobenzoic acid crystallizes in needles or leaflets, sublimes
in white needles and melts at 142°. After slow cooling it melts at 135-136° and
dissolves in 425 parts of water at 16.5°. (l, i^-Nitrobenzoic acid, also obtained
by oxidizing para-nitrotoluene, forms yellowish leaflets, melts at 240° and dissolves
with difficulty in water.

When the (I, 3)-brombenzoic acid is nitrated two nitrobrombenzoic acids are
produced, the one melting at 251°, the other, much more soluble in water, at 141°.
In both the nitrogroup is contained in the ortho -position and hence in reduction
both yield (l, 2) ^= (l, 6)-amidobenzoic acid (p. 562). The halogen of the nitro-
haloid benzoic acids is very reactive (compare p. 588, Berichte, 22, 3282).

Dinitrobenzoic Acid, CgH3(N02)2C02H (i, 2, 4 — COjH in i), is formed
by oxidizing o-dinitro-toluene with fuming nitric acid, and consists of long prisms,
melting at 169°. In the reduction with tin and hydrochloric acid the carboxyl
group is split off^and (i, 3)-diamidobenzene results.

The nitration of (i, 3)-nitrobenzoic acid with nitric and sulphuric acid produces
the symmetrical dinitrobenzoic acid (1,3, 5), which is also obtained by oxidizing
symmetrical dinitrotoluene. It crystallizes from water in large quadratic plates,
melting at 205°- Its reduction affords diamidobenzoic acid which yields (i, 3)-
diamidobenzene, when distilled with baryta.

The nitration of (i, 2)-nitrobenzoic acid produces three dinitrobenzoic acids :
(l, 2, 6), (I, 2, 5) and (i, 2, 4) — the latter being identical with the acid obtained
from a-dinitrotoluene. The first acid melts at 202° and when heated decomposes
into carbon dioxide and (l, 3)-dinitrobenzene. The second melts at 177° and when
reduced yields 'a diamidobenzoic acid which affords (l, 3)-diamido-benzene when
distilled with baryta (see the diamido-benzoic acids).

Amido-benzoic Acids, C6H4(NH2).C02H.

These are obtained by reducing the corresponding nitrobenzoic
acids with tin and hydrochloric acid, or with hydrogen sulphide in
ammoniacal solution. In the latter case the amido-acid is precipi-
tated from the solution by acetic acid. They are also formed by
the oxidation of the acetyl toluidines (p. 623). Dimethylated
amido-acids are produced by the action of phosgene (COCI2) upon
the dimethylanilines (p. 739) : or by methylating the acids by
heating them with alkyl iodides and caustic alkali. Like glycocoll,
the amido-benzoic acids yield crystalline salts both with acids and
bases.

Ortho-amidobenzoic Acid (i, 2) also results from the two
nitro-metabrombenzoic acids (p. 747) by reduction, and by the
action of sodium amalgam. It was first obtained from indigo,
hence termed anthranilic add.

It is prepared by oxidizing indigo. This is effected by boiling it with manga-
nese dioxide and sodium hydroxide (Annalen, 234, 146), or more readily if ortho-
nitrobenzoic acid be reduced with tin and hydrochloric acid. Also by the oxida-

MONOBASIC ACIDS. 749

tion of aceto-ortho-toluidine with potassium permanganate and boiling with
hydrochloric acid.

The formation of dibromanthranilic acid, when bromine acts upon boiling
orthonitrotoluene (p. 590), is worthy of note.

Anthranilic acid sublimes in long needles, is readily soluble in
hot water and alcohol, melts at 144°, and decomposes into carbon
dioxide and aniline when rapidly heated. Nitrous acid converts it,
in aqueous solution, into salicylic acid.

The inner anhydride (lactam) of ortho-amidobenzoic acid is the so-called

Anthranil, C^H^^' „„ p (see Berichte, 20, 1537), obtained by the reduction of

o-nitrobenzaldehyde with ferrous sulphate (theoretical quantity) and ammonia
{Berichte, 15, 2572), or with tin and glacial acetic acid {Berichte, 15, 2105 ; 16,
2227). It also results when ff-nitro-phenyloxyacrylic acid is boiled with water
{Berichte, 16, 2222). It is an oil which volatilizes readily with aqueous vapor,
possesses a peculiar odor and boils with decomposition about 210°. It dissolves in
alkalies, forming salts of anthranilic acid. s-Amidobenzaldehyde and benzalcohol
are produced when it is reduced. Chlorcarbonic esters produce Anthranilcar-

bonic Acid, C,HY^^C02H,orC6H^/^°~^^^0(^mV/^/^, 22, 1676),

which may also be obtained by oxidizing a glacial acetic acid solution of isatin
and indigo with chromic acid (hence called isatoic acid, Berichte, 17, Ref. 488).
It crystallizes from hot water or alcohol in colorless needles or plates. It dissolves
with much difficulty in most solvents. It melts about 233-240°, decomposing at
the same time into carbon dioxide and anthranil. Digested with alkalies or boiled
with acids, it decomposes into carbon dioxide and anthranilic acid. See Berichte,
19, Ref. 66 upon ^-methylisatoic acid,

Acetyl-anthranilic Acid, CgH^C^ ^^i r-r\ n\i ' rfisults when acetyl-(?-tolui-

dine is oxidized, when o-amidobenzoic acid and anthranil (see above) are acted
upon with acetic anhydride, and in the oxidation of methyl ketol and quinaldine
(see these). It forms flat needles, melts at 180° and is readily decomposed into
acetic and anthranilic acids. Benzoyl-anthranilic Acid melts at 182°.

«-Benzam-oxalic Acid, C^H^^ NH CO TO H' Oxalyl-amido-benzoic acid,

carbostyrilic acid, kynuric acid, is prepared synthetically by heating anthranilic
acid with oxalic acid to 130° {Berichte, 17, 401 and Ref no); it is also ob-
tained from indoxylic acid, from carbostyril, aceto-tetrahydroquinoline, kynurene
and kynurenic acid (see these). It crystallizes from hot water in long needles
containing one molecule of water (CgH,N05.H20), and melts with decomposition
at 200°. In a dessicator, more rapidly at 70-80°, it loses water and evolves car-
bon dioxide at 100°. When digested with alkalies it is decomposed into anthra-
nilic and oxalic acids. Its ethyl ester, from the ester of indoxanthinic acid
{Berichte, 15, 778), melts at 180°.

Similar compounds, e. g., benzamoxalic acid, are prepared, too, from meta-
amidobenzoic acid, by means of oxalic and malonic acids {Berichte, 18, 214;
see also Berichte, ig, Ref. 252).

Meta-amidobenzoic Acid (I, 3), from OT-nitrobenzoic acid, consists of aggre-
gations of needles, dissolves readily in hot water and melts at 173-174°. It reacts
acid, forming salts with acids and bases. The ethyl ester, obtained by reducing
»?-nitrobenzoic ester, is a thick oil. When in aqueous solution nitrous acid con-
verts it into ordinary oxy-benzoic acid. Cyanogen chloride acts on it to form

750 ORGANIC CHEMISTRY.

»z-cyanamido-benzoic acid, CsH4<^j^j| q-^. This yields uramido-benzoic acid,
CjHj^Sj^^Q j,jT , with hydrochloric acid (p. 392). The latter is also pro-
duced by ftising together meta-amido-benzoic acid and urea, or by mixing the
hydrochloric acid salt with potassium cyanate. It contains one molecule of water,
and forms small needles. Whefi heated it becomes urea-dibenzoic acid, CO(NH.
CeH^.COjH)^ {Berichte, 15, 2122).

Para-amidobenzoic Acid, from paranitrobenzoic acid, or from para-toluidine,
crystallizes in needles, is rather easily soluble in water, and melts at 186-187°.
Nitrous acid converts it into para-oxybenzoic acid.

The amido-benzoic acids, just like the anilines (p. 653), are changed, through

the diazo-compounds,. into Hydrazine-benzoic Acids, C5H^^j,j|„„. Of
these the ortho-body (from anthranilic acid), is the one which, whrti exposed to a
temperature of 230°, forms the inner anhydride, C^H^^ j^tt ■^^^^^'{Berichte, 14,
478). /NH

Dinitro-para-amidobenzoic Acid, C5H2(N02)2(' ro 'h' Chrysanisic

Acid, results when dinitro-anisic and dinitro-ethyl para-oxybenzoic acids are
digested with aqueous ammonia. The group O.CH3 is supplanted by NHj
(P- 593) :—

CeH,(NO,),/go^^^3 + NH3 = C,H,(NO,).(^0^|l + CH3.OH.
Dinitroanisic Acid. Chrysanisic Acid.

Chrysanisic acid forms light, golden-yellow leaflets or needles, melts at 259°
and sublimes.

Diamidobenzoic Acids, CjH3(NH5j)2.C02H. Four of the six possible
isomerides are known. The elimination of CO2 by one of them gives rise to para-
phenylene diamine, two others yield ortho-, and the third meta-phenylene diamine.
These acids conduct themselves towards the diazo-benzene-sulphonic acids, just
the same as the correspondmg phenylene- diamines [BericAte, 15, 2197).

Triamido-benzoic Acid, CsH2(NH2)g.C02H (l, 3, 4, 5— CO2 in i), has
been obtained from dinitro-para-amidobenzoic acid. It yields (l, 2, 3)-triamido-
benzene upon distillation (p. 625). For the isomeric acid (i, 3, 5, 6) steBeric/iie,
15, 2200.

AZO-BENZOIC ACIDS.

The action of sodium amalgam upon the mononitro-benzoic acids produces
(same as from the nitrobenzenes) azoxy-, azo- and hydrazo-benzoic acids
(p. 640) :—

C.H,{CO.H C,H,{SO.H C,H,{^O^H

1)0 II I .

r H /N/ r H /N „ „ fNH

"^s^nCO^H '-6"*tC02H "-s^^lcOaH

Azoxy-benzoic Acids. Azo-benzoic Acids. Hydrazo-benzoic Acids.

»2-Azobenzoic Acid, CijHjjNjOj + ;/^H20, azo-benzene-»2-dicarboxylic acid,
is precipitated by hydrochloric acid as a yellow, amorphous powder, and dissolves
with difficulty in water, alcohol and ether. When distilled it sustains "decomposi-
tion. It is a dibasic acid, and yields crystalline yellow salts and ethers. Azoben-

AZO-BENZOIC ACIDS. 751

zene is formed by the distillation of the copper salt ; the calcium salt yields azo-
diphenylene, Cj^HgNj. Para-azo-benzoic acid is a red, amorphous powder.

An azobenzene-mono-carboxylic acid, CjHj.Nj.CjH^.COjH, has been obtained
from amido-azobenzene by replacing its amido-group by cyanogen, etc. {Berichte,
19, 3022).

»i-Azoxy-benzoic Acid, C^HjoN^Oj (i, 3), is formed when the alcoholic solu-
tion of meta-nitrobenzoic acid is boiled with potassium hydroxide. Hydrochloric
acid precipitates it in yellowish masses.

»«-Hydrazo-benzoic Acid, Cj^HuN^O^ (l, 3), is obtained when ferrous sul-
phate is added to the boiling sodium hydroxide solution of w-azobenzoic acid.
Hydrochloric acid precipitates the acid in yellow flakes from the filtered solution.
It is not very soluble in hot alcohol. The aqueous solution of its salts absorbs
oxygen, and changes to azobenzoic acid. When boiled with hydrochloric acid it
is converted into the isomeric diamido-diphenyldicarboxylic acid (diamidodiphenic
acid), derived from diphenyl : —

^6^^\NH\ . J y"»\NH, .
^«"*\COjH ^6"3\COjH

this resembles the formation of benzidine from hydrazo-benzene (p. 650). The
latter acid is converted, by distillation with baryta, into benzidine and carbon
dioxide. Two additional isomeric acids are produced by reducing m-azo- and
azoxybenzoic acids with stannous chloride {Berichte, 23, 913).

Diazo- compounds. The aromatic amido-acids, analogous to the anilines, form
diazo- and diazo-amido-compounds (p. 629) : —

r w /COjH P TT /COjH

<-6J^4\N=N.N03 ^«"*\N = N— NH.CsH4.CO2H.

Diazo-benzoic Acid Nitrate. Diazo-amidobeiwoic Acid.

The diazo-compounds are produced by the action of nitrous acid upon salts of the
amido-acids in aqueous or alcoholic solution, and sustain transpositions perfectly
similar to those of other diazo-compounds. The addition of nitrous atid to the
alcoholic solution of the free amido-acids causes the separation of the diazo-amido
acids, which dissolve with difficulty. These are produced, too, on mixing solu-
tions of the nitrates of the diazo-acids with amido-acids. When boiled with haloid
acids they decompose into substituted acids and amido-acids, which continue dis-
solved as salts : —

'^sHi^Nj.NH.CjHi.COjH + ^^^"^ =

<-6J^4\Br + ^s^iXCOjH-"^"^ + ^ 2-

The sulphates of the diazobenzoic acids, when boiled with hydrochloric, hydro-
bromic and hydrofluoric acids, are similarly converted into their corresponding
halogen benzoic acids. Hydriodic acid reacts at the ordinary temperatures
(Berichte, 18, 960).

m- Diazobenzoic Acid Nitrate, CjHsN^Oj.NOj, from (i, 3)-amidobenzoic acid,
is soluble with difficulty in cold water, and separates in colorless prisms which
explode with violence. Caustic potash precipitates a yellow and very unstable mass
from the aqueous solution. This is probably the free acid. Boiling water changes

752 ORGANIC CHEMISTRY.

it to »«-oxybenzoic acid. Bromine precipitates the perbromide, CjHjNjOjBrj,
as an oil, from the aqueous solutions; it solidifies in yellow prisms. It yields
metabrombenzoic acid when digested with alcohol. Aqueous ammonia converts
the perbromide into the diazoimide, CfHjN^OjN (p. 640), which crystallizes
from alcohol and ether in white leaflets. It is an acid, and forms salts with
bases.

Diazo-m-amidobensioic Acid, C14H11N3O4, is precipitated as an orange-red
crystalline powder when nitrous acid is led into the alcoholic solution of meta-
amidobenzoic acid. It is almost insoluble in water, alcohol and ether. It is a
feeble, dibasic acid ; its salts are very unstable in aqueous solution. When
heated with the haloid acids it yields the corresponding halogen benzoic acids
(see above).

Ortho- and para-amido-benzoic acids yield corresponding diazo- and diazo-
amido-compounds.

Cyanbenzoic Acids, CgH^^p^*

These are formed on boiling the HCl-diazo-benzoic acids with potassium cyanide
and copper sulphate in aqueous solution (p. 633) [Berichle, 18, 1496). o-Cyan-

benzoic Acid rearranges itself in its formation to phthalimide, C^^ p^ > NH
{Berichte, ig, 2283). ^

m- Cyanbenzoic Acid is readily soluble in ether, alcohol and hot water. It is a
white microcrystalline powder, melting at 217°, and subliming with partial decom
position. It forms isophthalic acid on boiling with the alkalies (Berichte, 20, 524).

p-Cyanbenzoic Acid consists of microscopic needles, melting at 214°. It yields
dicyanbenzophenone by the distillation of its calcium salt [Berichte, 20, 521).

Sulpho-benzoic Acids, C^'H.i.^r'r\xi '

On heating benzoic acid for some time with fuming sulphuric acid, or by con-
ducting the vapors of SO3 into the acid, we obtain as chief product Metasulpho-
benzoic Acid, and in smaller amount Parasulphobenzoic Acid.

The three isomerides can be obtained by oxidizing the three toluene sulphonic
acids with an alkaline solution of potassium permanganate (p. 665). The sul-

phamides or sulphamin-benzoic acids, C^H^^ oq ^-^TtT , are similarly obtained from

the toluene sulphamines, €5114(0113). SO2.NH2 (by potassium permanganate or
potassium ferricyanide Berichte, ai, 242). The o?-/.4o-derivative eliminates water

and passes readily into its inner anhydride — benzoic-sulphinide, Z^^'{^ > NH
[Berichte, 20, 1596; 22, 754, Ref. 662, 822). \°'-'2

o-Sulphobenzoic Acid dissolves readily in water, crystallizes in large tablets and

melts at 250°. Its amide-anhydride — benzoic-sulphinide, C^Yl/^^ >NH (see

above), dissolves in cold water with difficulty, and crystallizes from hot water or
alcohol in delicate needles, melting at 224°. It possesses an exceedingly sweet
taste (l part =: 200 parts cane sugar), hence has been called Saccharin. It has
been employed as a substitute for sugar in the case of diabetic patients (Tech.
Preparation, Berichte, 19, Ref. 375 and 471 ; 21, Ref. 100). When the sulphi-
nide is evaporated to dryness with hydrochloric acid it changes to the ammonium
salt of sulphobenzoic acid. Commercial saccharin contains 43-48 per cent, of
sulphinide and 50 per cent, of para-sulphamine benzoic acid [Berichte, 22, Ref.
822). In aqueous solution the sulphinide has a somewhat acid character being

HOMOLOGUES OF BENZOIC ACID. 753

able to form imide salts, CsH,( ?^ ^NMe, which are different from the salts of

salphamin-benzoic acid, C6H^(^gQ2^^ .

The alkyl iodides convert the sulphinide salts into ethers {Berichte, 21, Ref.
100). For the methyl saccharin from ^-toluidine sulphonic acid^ consult Berichte,
22, Ref. 719).

HOMOLOGUES OF BENZOIC ACID.
Acids, CsHsG,.

1. Toluic Acids, CgH^^pQ^ Methyl-benzoic Acids.

The three toluic acids are produced when the three xylenes are
boiled for soine time with dilute nitric acid (p. 571), and also by
the action of sodium and carbon dioxide, or chlorcarbonic esters,
upon brom- and iodo-toluene. The easiest course to pursue con-
sists in converting the three toluidines into tolunitriles, then saponi-
fying the latter with the alkalies or sulphuric acid (of 75 per cent.)
(see Berichte, 19, 756).

Orthotoluic Acid (i, 2) results upon heating phthalide with phosphorus and
hydriodic acid {Berichte, 20, Ref. 378). It crystallizes from hot water in long
needles, melting at 102.5°. It 's very volatile with steam. The calcium salt,
(CgH,02)2Ca -j- 2H2O, and the barium salt, (CgH,02)2Ba ■\- 2H2O, are readily
soluble in water, and crystallize in delicate needles. Chromic acid decomposes
it, yielding carbon dioxide; potassium permanganate forms phthalic acid.

Metatoluic Acid (1,3) is obtained by oxidizing pure xylene with dilute nitric
acid (p. 573) (pure metaxylene is only oxidized at 130-150°). The most satisfac-
tory course for its preparation consists in oxidizing wxylene sulphamide with
potassium permanganate, and then decomposing the sulphamide that results with
hydrochloric acid {Berichte, 14, 2349). It is more soluble in water than its two
isomerides, and crystallizes in minute needles, melting at 1 10° and boiling at 263°-
It is easily volatilized with aqueous vapor. , Chromic acid oxidizes it with ease to
isophthalic acid. Its calcium salt, (CgH,02)2Ca -\- 3H2O, is very soluble in
water.

Paratoluic Acid (i, 4) is obtained by boiling paraxylene or cymene for
several days with dilute nitric acid. It crystallizes from alcohol or hot water in
needles, melting at 180°; it boils at 275° (corrected). It is very volatile with
steam. Nitric acid or chromic acid oxidizes it to terephthalic acid.

2. Phenyl-acetic Acid, CeHs.CH.^.COaH, Alphatoluic Acid,

is obtained: from benzyl cyanide, CeHj.CHj.CN, when boiled
with alkalies; from mandelic acid, C6H5.CH(OH).C02H, by heat-
ing with hydriodic acid ; from vulpic acid by boiling with baryta ;
and from brombenzene and monochloracetic ester by means of
sodium.

To prepare it benzaldehyde is first changed to phenyl-chloracetic acid, C5H5.
CHCl.COjH (see mandelic acid) and the latter then reduced by zinc dust, in am-
moniacal solution {Berichte, 14, 240). A better procedure consists in boilisg

63

754 ORGANIC CHEMISTRY.

benzyl chloride with potassium cyanide, then saponifying the latter with caustic
potash, or with moderately dilute sulphuric acid [Berichte, ig, 195°), which is
a simpler method. The ethyl ester can be directly obtained from the cyanide by
conducting hydrochloric acid gas into its alcoholic solution {Berickte, 20, S92).

Phenyl-acetic acid crystallizes in shining leaflets, resembling
those of benzoic acid; it melts at 76.5°, and boils without decom-
position at 262°. Benzoic acid is formed when it is oxidized with
chromic acid. The methyl ester, Q^^O^.CVl^, boils at 220°; the
ethyl ester at 226°.

The CHj-group of phenylacetic esters, CjHj.CHj.COjR, cannot be replaced by
alkyls (distinction from benzyl cyanide, p. 734) (Berichie, 21, 1306).

Phosphorus pentachloride converts the acid into phenyl acetic chloride, CgHj.

CHj.COCl, which boils at 102° under a pressure of 17 mm. It forms desoxyben-

zoin with benzene and aluminium chloride [Berickte, 20, 1389). Phenylacetic

anhydride, (CgH^.CHjCO)^©, is produced by the action of the chloride upon

• silver phenylacetate. It melts at 72°.

If the acid be acted upon by chlorine or bromine in the cold the halogens will
enter the benzene nucleus and in the para-position; if heat be applied the side-
chain will be substituted. The latter mono-halogen derivatives are also produced
from mandelic acid, CgH5.CH(OH).C02H, if it be heated with hydrochloric or
hydrobromic acid to 130-140°, and when boiled with alkalies regenerate mandelic
acid. Phenyl-chloracetic Acid, CgH5.CHCl.COjH, is also directly prepared
from CNH-benzaldehyde (see Mandelic Acid), crystallizes in leaflets, and melts at
78°. Phenyl-bromacetic Acid melts at 83-84°, and when potassium cyanide
acts upon its ester diphenyl-succinic acid is produced.

Phenyl-isonitroso-acetic Acid, CsH5.C(N.OH).C02H, is produced from
phenyl-glyoxylic acid (p. 762) with hydroxylamine and from isonitrosobenzyl
cyanide, C8H6.C(N.OH).CN; it melts at 128°. The ethyl ester, melting at 113°,
has been obtained from nitrophenyl-isonitroso acetic ester [Berichte, 16, 519).

Phenyl-amido-acetic Acid, C5H5.CH(NHj).C02H, results from phenyl-
isonitroso-acetic acid by reduction with tin and hydrochloric acid ; from phenyl-
bromacetic acid with ammonia, and from CNH-benzaldehyde, CgH5.CH(0H).
CN, by ammonia and saponification. It consists of pearly leaflets, melting at
256°. It decomposes, when distilled, jnto carbon dioxide and benzylamine.

Nitrophenyl-acetic Acids, C^^(^Q)^.CYi^.Q,0^.

The para-nitro acid, with a small amount of the ortho-nitro acid, is produced on
dissolving phenyl-acetic acid in cold, fuming nitric acid. These acids can be
separated by means of their barium salts. The three nitro-acids may be obtained
synthetically from the three nitrobenzyl cyanides, CgHj(N02).CH2.CN (p. 735).

o-Nitrophenyl-acetic Acid crystallizes from hot water in needles, melts at
'41° (137°). and by oxidation yields o-nitrobenzoic acid. w-Nitrophenyl-acetic
Acid melts at 120°. /-Nitrophenyl-acetic Acid dissolves with difficulty in
water, and melts at 152°- Further nitration of ortho- and para-nitrophenyl-acetic
acid produces (j/-Dinitrophenyl-acetic Acid (i, 2, 4), melting at 160°, and
decomposing into carbon dioxide and ff/-dinitro-toluene. Its methyl ester melts at
82°, and the ethyl ester at 35°. These dissolve in alcoholic alkalies, forming deep-
red colored salts, t. g., C8Hg(N02)i,.CHNa.C02R, the metal of which can be
replaced by other radicals [Berichte, 21, 1307, 2475). Diazobenzene chloride

HOMOLOGUKS OF BENZOIC ACID. 755

produces an azo- or hydrazone derivative. Its potassium salt, CjH3(N0j),.C(N.
NNa.CjH5).C02R, is deep blue in color, and is capable of entering a remarkable
transposition, leading to the formation of a pyrazole derivative {Berichte, 22,
320; 23, 1574).

Amidophenyl-acetic Acids, C6H4(NHj).CH2.C02H.

These can be obtained by reducing the nitro-acids. The ortho-
compound and other ortho-amido-acids can, by the exit of water,
form amide-anhydrides. This is analogous to the formation of lac-
tones (p. 351) from oxy-acids. The oxygen may be taken from
the hydroxy! or from the CO-group of carboxyl ; in the first instance
so-called lactams (inner amides) are produced, in the latter the
lactirnes (inner imides) : —

<=«^*\NHf °'°^ yields C,H,/^|^\C0 + H,0,

tf- Amidophenyl-acetic Acid. A Lactam, Oxindol.

C''H4<nhJ^°°^ yields C,H,/CO\c.OH + H,0.

(?-AmidophenyI-glyoxylic Acid. A Lactime, Isatin.

This anhydride formation sometimes occurs spontaneously in the
separation of the free acids from their salts (or in the reduction of
the nitro-compounds).

As yet, but one anhydride (lactam or lactime) has been obtained
from each acid ; the other form cannot necessarily be designated the
unstable or pseudo form j however, the two forms may probably be
tautomeric (p. 54). These anhydrides do yield two entirely dif-
ferent series of alkyl derivatives, depending upon whether the hy-
drogen of the NH-group in the lactam ethers, or the H .of hydroxyl
in the lactime ethers, is replaced by alkyl, e.g. : —

CeH.<Sfd^>CO and C,H /CO\c.O.CH,

Lactam Ether, Methyl Oxindol. Lactime Ether, Methyl Isatin.

The ethers of the lactams (in which the alkyl is attached to nitro-
gen) are very stable, whereas the lactimes are decomposed by
heating with hydrochloric acid. It is possible to prepare both
varieties of ethers with many of the anhydrides. This would indicate
that the two anhydride forms are identical (see Carbostyril and
Berichte, 18, 1528; 20, 2009).

The acids, with 2 and 3 carbon atoms in the side-chain, condense in this way;
the former yield indol-, the latter quinoline-derivatives : —

„ „ /CH,.CH,.CO.OH . ,, „ jj /CH,.CH

<7-Amidophenyl-propionic Acid. A Lactam, Hydrocarbostyril.

/CH:CH.CO.OH . , , „ H /CH:CH

fl-Amidophenyl-acrylic Acid. A Lactime, Carbostyril.

756 ORGANIC CHEMISTRY.

The indol-bodies contain a chain of 4 C-atoms (2 of which belong to the ben-
zene nucleus), closed by I N-atom (a chain of 5 members) — analogous to the
pyrrol compounds (p. 538) ; they may also be compared to the y-lactoues and the
furfurane compounds. In the qulnoline derivatives we have a chain of 5 C-atoms,
the same as in the (5-lactones. A ring of 3 C-atoms linked by N has only been
confirmed in the case of anthranil (p. 749) ; it is, however, analogously very un-
stable, as in the /3-lactones (p. 353).

The ortho-amido-derivatives of the aldehydes and ketones, in which the CO-
group represents the second or third member of the side-chain, are capable, too,
of condensing and producing compounds belonging to the iudol- and quinoline-
groups. Thus, from o-amidophenyl-acetaldehyde we get indol (p. 721); from
o-amidophenyl-acetone, methyl ketol (p. 730) ; and from o-amidobenzyl-acetone,
hydromethyl-quinoline (p. 730). Yet, chains (with 6 and more C-atoms and I
N-atom) having 7 or more members, could not be produced {Berichte, 13, 122 ;
14, 481 ; 20, 377).

^-Amidophenyl-acetic Acid passes immediately into its
lactam, oxindol, when it is produced (by reduction of the ortho-
nitro-acid). When oxindol is heated to 150° with baryta water,
water is absorbed and the- barium araidophenyl-acetate produced.
Acids liberate oxindol from it {Berichte, 16, 1704).

Acetyl-o-amido phenyl-acetic Acid, CgH4(NH.CO.CH3).CHj.C02H, is
obtained by dissolving acetyl oxindol in dilute sodium hydroxide ; it melts at 142°,
and when heated with alkalies or acids decomposes into oxindol and acetic acid.

»z-Amidophenyl Acetic Acid, from the nitro-acid, crystallizes from hot
water in leaflets, and melts at 149°- /-Amidophenyl-acetic Acid, from the
nitro-acid, consists of pearly leaflets, and melts at 200°.

When dinitrophenyl-acetic acid (p. 754) is reduced with tin and hydrochloric
acid, Diamido-phenyl-acetic Acid results, and this immediately passes into
/-amido-oxindoj, CgH|5(NH2)NO. Partial reduction of the dinitro-acid with am-
monium sulphide yields ;>-amido-o-nitro-phenyl-acetic acid, C,H3(NHj)(N02).
CHj.COjH. This treated with amy! nitrite and alcohol yields o-Nitrophenyl-
isonitroso-acetic Acid, CgH4(NOj).C(N.OH).C02H, and o-nitrobenzaldoxime
(p. 720). Isomeric/-Amido-»«-nitrophenyl-acetic Acid, from /-amidophenyl
acetic acid, yields »z-nitrobenzaldoxime with the same reagents. An isomeric
Pseudophenyl-acetic Acid, CgHgOj, seems to have been prepared by the
action of diazo-acetic ester upon benzene (p. 207). Homologous acids have been
formed in the same way [Berichte, 18, 2377).

Acids, CgHioOj.

I. Dimethylbenzoic Acids, C6H3(CH3)2.C02H. Four of the six
possible acids with this formula are known.

Mesitylenic Acid has the symmetrical structure (i, 3, 5), and is obtained by
gradually oxidizing mesitylene with dilute nitric acid. It crystallizes from alcohol
in large prisms, from water in needles ; it melts at 166° and sublimes very readily.
The barium salt, (C9H902)2Ba, is very soluble in water and consists of large,
shining prisms. The elhyl ester, C^M^[<Z^\\^)V)^, solidifies at 0° and boils at
241°- Distilled with excess of lime, mesitylenic acid yields isoxylene. Nitric
acid oxidizes it further to uvitic and trimesic acids.

HYDROCINNAMIC ACID. 757

The oxidation of pseudocumene (p. 574) with dilute nitric acid produces
xylic acid, C5H3(CHg)2.COjH(i, 2, 4— COjH in i), and so called para-xylic
acid (i, 3, 4) ; both distil with aqueous vapor and can be separated by means of
their calcium salts. Xylic acid has also been obtained from bromisoxylene by the
action of sodium and carbon dioxide. From alcohol it crystallizes in long prisms,
dissolves with difficulty in water, melts at 126° and sublimes readily. Its calcium
salt, (CgH502)2Ca 4- 2H2O, forms thick prisms and is more easily soluble- in
water than the salt of paraxylic acid. Isoxylene results when it is distilled with
lime. Nitric acid oxidizes it to xylidic acid, CjH3(CH3).(C02H)2; chromic acid
decomposes it into carbon dioxide.

Paraxylic acid crystallizes from alcohol in concentrically grouped needles and
melts at 163°. Its calcium salt contains three and one- half molecules of water and
consists of needles. Distilled with lime it yields ortho-xylene ; both methyl groups,
therefore, occur in the ortho-place. Oxidation converts it into xylidic acid.

2. Tolyl-acetic Acids, CgH^^^^^' ^q jj, Alpha-xylic Acids. The

three isomeric acids have been obtained from the three xylene bromides, CjH^
(CH3).CH2.Br, by means of the cyanides {Berichte, 15, 1744). The orthoz.c\A
melts at 89° ; the meta at 6l°, and 'Has para at 91°. The latter acid has also been
obtained from tolylglyoxylic acid by reduction with hydriodic acid and phospho-
rus. It melts at 72° {Berichte, 20, 2051).

3. Ethyl-benzoic Acids, Q^/pX A. The para-acid (l, 4) may be ob-
tained by oxidizing para-diethyl benzene with nitric acid, and from para-brom-
ethyl benzene, C^^x.Q,^^, by the action of sodium and carbon dioxide. It
crystallizes in leaflets from hot water, melts at 112° and sublimes readily. Oxida-
tion converts it into terephthalic acid. The ortho-acid is formed by reducing
acetophenone carbonic acid with hydriodic acid. It melts at 62°.

(4) The phenylpropionic acids, CgHj.CjH^.COjH, are hydrocinnamic acid and
hydroatropic acid : —

(d) Hydrocinnamic Acid, C6H5.CH2.CH2.CO,H, /S- Phenyl-
propionic Aci4, is obtained : by the action of sodium amalgam
■upon cinnamic acid (phenylacrylic acid), or upon heating the latter
with hydriodic acid {^Berichte, 13, 1680) ; when potassium cyanide
acts upon a-chlorethylbenzene, CeHj.CHz.CHjCl (p. 586); from
benzyl aceto-acetic ester and benzyl malonic ester, also from ben-
zylic acetic ester (p. 740) ; and in the decay of albuminoid sub-
stances. It is very soluble in hot water and alcohol, crystallizes in
needles, melts at 47° and distils without decomposition at 280°.
Chromic acid oxidizes it to benzoic acid.

Haloid Hydrocinnamic Acids, of the formula CjH5.CHX.CH2.CO2H, are
obtained from cinnamic acid, CgHj.CHiCH.COjH, by the addition of the
haloid acids (p. 223) and by the action of these upon /3-phenyl-hydracrylic acid,
CgH5.CH(OH).CH2.C02H. On heating or boiling with water the free acids
decompose (as p-oxyacids are produced at first, p. 346) into the haloid acid and
cinnamic acid; when neutralized with alkaline carbonates they split up, even in
the cold, into a halogen acid, carbon dioxide and styrolene, C5H5.CH:CH2.
^-Chlor-hydro-cinn|imic acid, CsH5.CHCl.CH2.CO2H, melts at 126°; the
brom-acid at 137°, the iodo-aciS at 120°-

ajS-Dibromhydrocinnamic Acid, CjHj.CHBr.CHBr.COjH, Cinnamic
Bromide, is formed by the addition of bromine to cinnamic acid (dissolved in

758 ORGANIC CHEMISTRY.

CSj) {Annalen, 195, 140). It crystallizes from alcohol in leaflets, melts at 201°,
and decomposes. When digested with a soda solution it is decomposed into
a-bromstyrolene, CgH5.CH:CBrH, carbon dioxide and hydrobromic acid; when
boiled with water phenyl o-bromrlactic acid is also produced. a;8-Dichlorhydro-
cinnamic Acid deports itself similarly, and melts at 163° {Berichte, 14, 1867).

a- and /3-Monobrom-cinnamic acids are produced when dibromhydro-cinnamic
acid is treated with alcoholic potassium hydroxide (see this).

Phenylamido-profionic Acids.

Phenyl-a-amido-propionic Acid, C6H5.CH2.CH(NH2).C02H, Phenylala-
nine, is produced from phenyl-acetaldehyde with prussic acid and ammonia (An-
nalen, 219, 186). It is soluble with difficulty in both cold water and hot alcohol.
It crystallizes in leaflets or prisms. It doesnot part with ammonia when boiled with
caustic potash or concentrated hydrochloric acid. It readily copibines to form
salts with bases and acids. When slowly heated it sublimes without decomposi-
tion; quickly heated phenyl ethylamine and a lactimide are produced. It also
occurs in the sprouts (along with asparagine) of Lupinus luteus, and is formed in
the decay of albumen [Berichte, 16, 171 1).

The nitration of phenyl-alanine yields the para-nitro-corapo\mA, which by
reduction becomes /-Amidophenyl-alanine, C5H4(NH2).CH2.CH(NH2).C02H.
The latter is also obtained in the reduction of dinitro-cinnamic acid, C5Hj(N02).
CH:C(N02).C02H (Berichte, 16, 852), and when acted upon by one equivalent
■of nitrous acid forms tyrosine (Annalen, 2ig, 170).

Sf Phenyl-/3-amidopropionic Acid, C8H5.CH(NH2).CH2.C02H, is obtained on
treating /3-bromhydro- cinnamic acid with aqueous ammonia; it is easily soluble
in water and alcohol, melts at I2i°, and when boiled with acids decomposes into
NHj and cinnamic acid. It does not combine with bases, and with difficulty with
acids (Berichte, 17, 1498).

The Halogen-hydrocinnamic Acids, CgH^.X.CH^.CHj.COjH, containing
the substitutions in the benzene nucleus, are obtained from the corresponding halo-
gen cinnamic acids on heating them with hydriodic acid and phosphorus (Berichte,
15, 2301 ; 16, 2040).

Nitrohydrocinnamic Acids, C^^(^Q^.C&.^.Q.Yi^.Q.<:)fi..

The nitration of hydrocinnamic acid produces the para and ortho acids, which
can be separated by crystallization from water. o-Nitrohydrocipnamic Acid is
more easily obtained from the dinitrohydrocinnamic acid (see below). It forms
small yellow crystals, and melts at 113°-

wz-Nitrohydrocinnamic Acid results from /-amido-wj-nitrohydrocinnamic
acid (see below) by the elimination of the amido-group, and melts at 118°.
/-Nitrohydrocinnamic Acid melts at 163°, and is oxidized to /-nitrobenzoic
acid. by a chromic acid mixture.

Amido-hydrocinnamic Acids, CjHj(NH2).CHj.CIIj.C0jH.

o-Amido-hydrocinnamic Acid. When this acid is formed by the reduction
of o-nitrocinnamic acid with tin and hydrochloric acid it a^ once changes to its
lactam, Hydrocarbostyril, C9H5NO (p. 755). The latter is intimately related
to quinoline, CjHjN, dissolves readily in alcohol and ether, crystallizes in prisms
melts at 160°, and distils undecomposed.

HYDRO-ATROPIC ACID. 759

While the lactime of o-amido-hydrocinnamic acid is unstable, its ethers exist,
as do those of the lactam (hydrocarbostyril) (p. 755): —

C,H / 'I and C,H / |

\N(C,HAC0 \n = CCO.QHj)

Hydrocarbostyril Ether. Lactime Ether.

The former is produced from hydrocarbostyril by means of ethyl iodide and
alcoholic potassium hydroxide; it is very stable; the latter, formed in the reduc-
tion of fl-nitrohydrocinnamic ether, is saponified on heating with hydrochloric acid
{Berichie, 15, 2103).

M-Amidohydrocinnamic Acid, prepared by reducing the z«-nitro-acid with
tin and hydrochloric acid, melts at 85°. /-Amido-hydrocinnamic Acid melts
at 131°. Energetic nitration of hydrocinnamic acid produces /o-dinitro-hydro-
cinnamic acid, CgH3(NOj)2.C2H4.C02H (i, 2, 4), which melts at 126°- Reduc-
tion with ammonium sulphide affords /-amido-o-nitrocinnamic acid, melting at
139°. By the elimination of the NHj-group we get o-nitrohydrocinnamic acid.
The reduction of the dinitro-acid with tin and hydrochloric acid brings about con-
densation of the diamido-acid at once to /-amido-hydrocarbostyril, C9Hg(NH2).
NO (p. 756), melting at 211° (Berichte, 15, 842, 2291).

The /-Amido-ff2-nitrohydrocinnamic Acid, CeH3(NH2)(N02).C2H4.C02
H, is formed in the nitration of aceto-j*amidohydrocinnamic acid, melts at
145°, and by the elimination of the amido-group yields w-nitrohydrocinnamic
acid.

(^) Hydro-atropic Acid, C6H5.CH(' qq'jj, a-Phenyl-pro-

pionic Acid, is obtained from atropic acid, CgHaOj = C5H5.
C(CH2).C02H, by the action of sodium amalgam, and from aceto-
phenone, CeH5.CO.CH3, when acted upon with hydrocyanic and
hydriodic acids {Annalen, 250, 135). It is an oil, boiling at 265°,
and is volatile in aqueous vapor. Potassium permanganate oxidizes
it to atrolactinic acid (p. 775) by changing tertiary hydrogen to
hydroxyl.

Bromhydro-atropic Acids : — ■

(a) qn^.CBr/^^^ajj (/3) C,H,.Ch(^^^^^' .

Both isomerides result from the addition of HBr to atropic acid, CgHgOj. The
a-acid, obtained from atrolactinic acid, CgH-^^O^, by means of hydrobromic acid,
melts at 93°, and reverts to atrolactinic acid on boiling with a soda solution. The
;8-acid also melts at 93°, and when boiled with alkaline carbonates yields tropic
acid, C9H1 0O3, together with atropic acid and styrolene. The chlorhydro-atropic
acids deport themselves similarly {Annalen, aog, 21).

/- and a- Nitrohydro-atropic Acids are obtained by nitrating hydro-atropic acid
in the cold. The/a^a acid melts at 88°, and by reduction yields /-amido-hydro-
atropic acid, which by diazotizing passes into the /-oxy-acid (phloretinic acid).
The ortho-nitro-acid yields an amido acid which immediately, by loss of Water,

passes into its lactam, atroxindol, C^e^iL^^} NH/^*^ ^P' ^^^^ {Berichte,
18, Ref. 230). ' ■ '^

760 ORGANIC CHEMISTRY.

Acids, CjjHjjOj.

(i) Durylic Acid, C6H2(CH3)3.C02H, obtained by the oxidation of durene,
crystallizes in hard prisms, and melts at 115°. The two hydrogen atoms in it
occupy the para position; therefore, when diamido-durylic acid is oxidized its
quinone, trimethylquinone carboxylic acid, is produced {Berichte, 18, 3496).

(2) The oxidation of isodurene affords three Isodurylic Acids, the a- melting
at 215°, the P- at 151°, and y- at 84°. When these split off carbon dioxide the
corresponding trimethyl benzenes result; from the a we get hemi-mellithene, from
the ft mesitylene and from the y, pseudocumene (^Berichte, 15, 1855).

{3) Propyl Benzoic Acids : six isomerides.

/ C H
Cumic Acid, CsH^^ ^q Vt, /-isopropyl benzoic acid (contain-
ing the isopropyl group), is produced by the oxidation of cuminic
alcohol and aldehyde with dilate nitric acid, or by the action of
potassium hydroxide (p. 709). It has been synthetically prepared
from ;)-bromcumene, CsH^Br.CsH, (with isopropyl, p. 575), by the
action of sodium and carbon dioxide (Berichte, 15, 1903). It is
furthermore produced by the oxidation of cymene (p. 577) in the
animal organism ; a transposition of normal propyl occurs in this
case.

It is obtained from cuminol (Roman caraway oil) by fusion with caustic potash,
or what is better, by the oxidation with an alkaline potassium permanganate solu-
tion {Berichte, 11, 1790).

Cumic acid is very soluble in water and alcohol, crystallizes in
needles or leaflets, melts at 116°, and boils about 290°. It yields
cumene (isopropyl benzene) when distilled with lime. Chromic
acid oxidizes it to terephthalic acid and potassium permanganate
converts it into oxypropyl-benzoic acid, C6H4(C3H6.0H).C02H,
and acetobenzoic acid (p. 760).

Normal Cumic Acid, C8H4(C3H,).C02H, /-normal propylbenzoic acid
(with normal propyl), is obtained by oxidizing propylisopropyl benzene and dinor-
mal propyl benzene with dilute nitric acid (Berichte, 16, 417); also synthetically
from /-bromprbpyl benzene, CgH^Br.CjH, (with normal propyl), by the action
of CO 2 and Na. It is volatile with aqueous vapor, crystallizes in shining needles
or leaflets, and melts at 140°. o-Normal Propyl-betizoic Acid (i, 2), is produced
when phthalyl propionic acid is reduced with hydriodic acid. It melts at 58°.

(4) Tetramethylbenzene Carboxylic Acid, CgH(CH3)4.C02H, Durene
Carboxylic Acid, results upon treating durene with phosgene in the presence of
aluminium chloride. It melts at 179°, volatilizes with steam, and if heated to
200°, together with concentrated hydrochloric acid, breaks down into carbon
dioxide and durene. Its cyanide is formed upon distilling the acid with lead sul-
phocyanide. It melts at 77° (Berichte, 22, 1223).

Pentamethyl Benzoic Acid, €5(0113)5. COjH, is formed from pentamethyl-
benzene by the action of phosgene and AICI3. It melts at 210°. If heated with
lime or hydrochloric acid it breaks down into pentamethyl benzene and carbon
dioxide. Its cyanide, Q-f^{CSA^^.C^,\% produced in the same manner as that of
the preceding acid. It cannot be saponified by acid or alkalies, but decomposes
into ammonia, carbon dioxide and pentamethyl benzene (Berichte, 22, 1221).

KETONIC ACIDS. 761

Aldehyde Acids.

Phenyl Formyl Acetic Acid, C6H5.CH(CHO).C02H, belongs to this class.
Its esters are obtained similarly to the ketonic esters (see below) by the action of
sodium ethylate upon phenyl acetic esters, C5H5.CH2-C02Ri and formic esters,
CHO.OR. It is an oily liquid, boiling at 144-145° under a pressure of 16 mm.
Ferric chloride imparts a blue-violet coloration to its alcoholic solution. The free
acid is very unstable. The ester, acting as a j8-keton-compound, condenses with
phenylhydrazine to diphenylpyrazolon (Berichte, 20, 2933).

1^^

KETONIC ACIDS.

The acids of this class in the benzene series are perfectly analo-
gous to those of the paraffin series. A rather remarkable method
for their formation is that of the union of benzoic esters with fatty-
acid esters, alcohol being eliminated, and also the union of aceto-
phenone, CsHs.CO.CHa, with carbonic acid esters and esters of
oxalic acid. The reaction is similar to that occurring in the forma-
tion of ketones (p. 726). It follows by the action of dry or alco-
holic sodium ethylate upon a mixture of the two components
(Claisen, Berichte, 20, 655, 2178), or by the action of metallic
sodium (Wislicenus and Piutti, Berichte, 20, 589, 537, 2930): —

CjH5.CO.OR + CH3.CO2R = CeH5.CO.CHj.CO2R -I- ROH,

Acetic Acid Ester of Benzoyl

Ester. Acetic Acid.

CgH^.CO.CHa + RO.CO2R = CjH5.CO.CH2.CO2R + ROH,

Carbonic Acid
Ester.

CeH5.CO.CH3 + RO.CO.COjR = CgHj.CO.CH^.CO.COjR -|- ROH.

Benzoyl Pyroracemic
Acid.

Phenyloxalacetic ester {^Berichte, 20, 592) is similarly obtained from phenyl-
acetic ester and oxalic ester : — ■

CjHj.CH^ + RO.CO.CO2R = C5H5.CH.CO.CO2R -f ROH.

io^R tOjR

Phenyl pyroracemic acid, CgH5.CH2.CO.CO2H, is again obtained from this
by the ketone decomposition (upon boiling with dilute sulphuric acid).

Nascent hydrogen converts all the ketonic acids into oxyacids.

I. a-Ketonic Acids.

These like those of the fatty series are produced (i) by the action of hydrochloric
acid upon the cyanides of the acid radicals ; (2) by the action of chloroxalic esters
upon the benzenes in the presence of AICI3 [Berichte, 20, 2048) : —

C^Hg -H CI.CO.CO2.C5H1, = CeH5.CO.C02.C5Hii + HCl;

(3) by the oxidation of acetyl benzenes (containing a methyl group in addition to
the acetyl group) with potassium permanganate or potassium ferricyanide (Be-
richte, 20, 2213; 23, Ref. 641) : —

64

/CH3 vipldi r H ^^^^i

*\CO.CHi, ^^°^ ^^"^xCO.COjH.

762 ORGANIC CHEMISTRY.

I. Benzoyl Formic Acid, CjHj.CO.COjH, Phenylglyoxylic Acid, is obtained
in the action of fuming hydrochloric acid at ordinary temperatures upon benzoyl
cyanide, C5H5.CO.CN, and by oxidizing acetophenone with potassium ferri-
cyanide {Berichie, 20, 389), as well as by oxidizing benzoyl carbinol, styrolene
alcohol (p. 712) and mandelic acid with dilute nitric acid or permanganate. Its
elhyl ester is formed when ethyl chloroxalic ester acts upon mercury diphenyl, or
benzene in the presence of AICI3. The acid is separated from its salts in the form
of an oil, which slowly solidifies on standing over sulphuric acid. It is very
soluble in water, melts at 65-66°, and when distilled decomposes into CO and
benzoic acid, to a less degree into CO^ and benzaldehyde. When mixed with
benzene containing thiophene and sulphuric acid, it is colored deep red, after-
ward blue-violet; all its derivatives, and also, isatin, react similarly. Its ethyl
ester boils at 252°.

Being a ketonic acid it (its esters) unites with sodium bisulphite. It combines
with CNH, forming oxycyanides, CsH5.C(OH)(CN).C02H, from which phenyl
tartronic acid is derived. Sodium ^malgam converts it into mandelic acid, and
hydriodic acid and phosphorus at 160° into alphatoluic acid. Hydroxylamine
converts it into phenylisonitroso-acetic acid (p. 754). Phenylhydrazine forms a
hydrazone with it {Berichie, 23, 1575).

o-Nitrobenzoyiformic Acid, CgH4(N02).CO.C02H, is formed from o-nitro-
benzoyl cyanide, by means of potassium cyanide, etc. It crystallizes with one
molecule of water, and melts at 47°. It forms two isomeric hydrazones (Berichte,
23, 2080). When anhydrous it melts with decomposition at 122°- Ferrous
sulphate and sodium hydroxide reduce it to —

(7-Amido- phenylglyoxylic Acid, QHiCNHO.CO.COaH,
Isatiiiic Acid. It is a vt^hite powder, obtained from its lead salt by
hydrogen sulphide. Digestion of its solution converts it at once
into its lactime — isatin, QHsNOj (p. 755)-

CO.CO
The lactam of isatinic acid, CgH^^ / (p. 755), is unstable; the aceto-

derivative, aceto-pseudo-isatin (see this), however, is stable. It dissolves in alkalies,

/CO 00 TT
forming salts of Aceto-isatinic Acid, CgH^;' ^r^ _ «„„ , from which the

latter may be separated by dilute acids. The acid dissolves with difficulty in cold
water, crystallizes from alcohol in needles, and melts at 160°. Boiling hydro-
chloric acid decomposes it with separation of isatin. When in an acetic acid
solution it is reduced to aceto-o-amido mandelic acid by sodium amalgam (p. 774).

j!>-Dimethylaniido-phenylglyoxylic Acid, {C¥i^)^:^.<Z^Yl^.CO.<ZO^M, is
produced from dimethyl aniline and chloroxalic ester (p. 601). It melts at 187°.

2.V-Toluyl-formic Acid, CgHjOg = CsH4(CH3).C0.C02H, Tolylgly-
oxylic Acid, is obtained from toluene, chloroxalic ester and AICI5 {Berichte, 20,
2048), as well as by oxidizing /-methyl- tolyl ketone with potassium ferricyanide
{Berichie, 20, 1763). It does not volatilize with steam. It crystallizes from an
ethereal solution and melts about 96°. Its phenylhydrazine derivative melts at
144° Potassium permanganate oxidizes it to /t-toluic and terephthalic acids. It
yields /-tolyl-oxyacetic and/ tolyl-acetic acids upon reduction (p. 757).

3. Phenylpyroracemic Acid, C^HgOs = CsH5.CH3.CO.CO2H, results
from the union of phenyl- acetic ester and oxalic ester by the elimination of carbon
dioxide from the phenyl-oxalacetic acid produced at first. It is identical with
phenylglycidic acid, from benzoylimido-cinnamic acid {Berichte, 17, 1616) and
phenyl-^-bromlactic acid. It dissolves with much difficulty in water, crystallizes

BENZOYL ACETIC ACID. 763

in brilliant leaflets, and melts at 154°. Ferric chloride imparts an intense green
color to its solution. \\s phenylhydrazone melts at i6i°. Being an a-diketone, it
yields a quinoxaline with o-toluylene diamine {Berichte, 20, 2465).

4. Xylyl Glyoxylic Acids, CioHioOj = CeH3(CH3)2.CO.C02H, result upon
oxidizing xylylmethyl ketones {Berickte, 19, 230; 20, 1766).

/S-Ketonic Acids.

In addition to the general reactions given upon p. 761, this class
of acids may also be prepared by the action of the benzaldehydes
upon diazoacetic esters (p. 374) {Berickte, 18, 2371) : —

C5H5.COH + CHNj.CO^R = CjH5.CO.CH2.CO2R + Nj.

The /9-ketonic-acids form pyrazole compounds with phenylhydra-
zine (p. 339).

I. BenzoylAceticAcid, QHs.CO.CHj.COjH. Its ethyl ester
was first prepared by dissolving phenyl-propiolic ester in sulphuric
acid and then diluting with water (p. 726) {Berickte, 16, 2128) : —

CjHs.C : CCOjR + HjO = CeHj.CO.CHj.COjR.

It is also formed when benzaldehyde is heated with diazo-acetic
ester, and by the action of sulphuric acid and water upon a-brom-
cinnaraic ester {Berickte, 19,1392). It is most conveniently made
by the action of dry sodium ethylate or sodium upon ethyl benzoate
and acetic ester {Berickte, 20, 653, 2179).

Small quantities of the ester are produced when esters of carbonic
acid act upon acetophenone. Benzoylacetic ester is an oil with an
odor resembling that of aceto-acetic ester. It boils at 265-270°
with slight decomposition. The/rfi?acid is obtained by saponifying
the ester at the ordinary temperature with potassium hydroxide. It
dissolves with difficulty in water, very readily in alcohol and ether,
and crystallizes in needles. When rapidly heated, these melt at
103-104°, decomposing into carbon dioxide and acetophenone.
Boiling acids produce the same decomposition. Ferric chloride
imparts a deep violet color to its aqueous solution.

Benzoyl-acetic ester unites with aniline, forming /3-phenylamido-phenylacrylic
ester, which yields a-phenyl-7-oxyquinoline by condensation {Berickte, 21, 521).

Diazobenzene chloride converts benzoyl acetic ester into the phenylhydrazone
of benzoyl-glyoxylic ester, CeH5.CO.C(NjH.C6H5).C02.C2H5 (p. 652) {Berickte,
21, 2120).

The CHj-group of benzoyl-acetic ester can be replaced by alkyls and radicals.

Methylbenzoyl-acetic Ester, C5H5.CO.CH(CH3).C02R, when treated with
nitrous acid eliminates the COj group (p. 338) and forms a-isonitrosopropiophenone,
C8H..CO.C(N.OH).CH3 (^otV/4/^, 21, 2119).

Allyl-benzoyl-acetic Acid, C5H5.CO.CH(C3H5).C02H, is isomeric with
benzoyl-tetramethylene carboxylic acid (p. 520) and melts at 122-125°.

/-Nitrobenzoyl-acetic Acid, CeHi(N02).C0.CH2.C02H, melts at 135°,
and is produced in a manner analogous to that of benzoyl acetic acid, i. e., by
heating /-nitrophenyl propiolic ester, CjH4(N02).C;C.C02R, to 35° with sul-

764 ORGANIC CHEMISTRY.

phuric acid, while o-nitrophenvl propiolic ester is transposed into the isomeric isa-
togenic ester {Berichte, 17, 326). For additional derivatives see Berichie, 18, 951.

2. Phenylaceto-acetic Acid, CgHj.CH^' ^q^^ ^. The ethyl ester of the

dinitro-acid, C5H3(N02)2.CH(CO.CH3).COjR, is obtained from sodium aceto-
acetic ester and o^-dinitrobrombenzene. It forms yellow prisms, melting at 94°
(Berichte, 21, 2470). The ester of the trinitro acid is obtained in a similar
manner from picryl chloride. It melts at 98° (Berichte, 23, 2720). See Berichte,
22, 990, for the action of tribromdinitrobenzene.

/CO CH

3. Benzylaceto-acetic Acid, CgH-.CHj.CHC^ P^-.' pr ^ Its ethyl ester is

derived from aceto-acetic ester and benzyl chloride (p. 337). It boils at 276° and
by the ketone decomposition yields benzyl acetone (p. 730) ; by the acid decompo-
sition it forms phenylpropionic acid (p. 759).

Of the class of 7-ketonic acids may be mentioned : —

1. Benzoylpropionic Acid, CgHj.CO.CHj.CHj.CO^H, which is obtained from
benzene and succinic anhydride by means of AICI3 : —

C^He + C,H,(CO),0 = CeH5.C0.C,H,.C0,H.

It is also formed by reducing benzoyl acrylic acid with HgNa ; by the elimination of
carbon dioxide from benzoylisosuccinic acid (p. 765), and from phenacyl-benzoyl-
acetic ester by the ketone decomposition. It dissolves with difficulty in hot water,
crystallizes in needles, and melts at 1 1 6°. Sodium amalgam reduces it to phenyl-
7-oxybutyric acid, which, upon the loss of vyater, becomes phenyl butyrolactone
(Berichte, 15, 1890) : —

CsHs.CHrOHj.CjHi.CGjH yields aHj.CH.C.H..

^CO + HjO.

Phosphorus pentasulphide converts the acid into phenyloxythiophene (Be-
richte, 19, 553).

The benzenes condense with other dibasic acid anhydrides, e.g., maleic and
phthalic anhydrides (see benzoyl acrylic acid).

2. Phenyl-lsevulinic Acid, CnHi^Os = CsHj.CH/^Q^j^^-^^s^is derived

from phenylacetosuccinic ester. Sodium amalgam converts it into a lactonic acid
(Berichte, 18, 790).

3. Acetobenzoic Acids, CgHg03=: CgH4<^^^ Vv ^^ acetophenone carboxylic

acids. The ortho form is produced upon heating benzoylaceto-carboxylic acid
(from phthalyl acetic acid, p. 765) to 100°, or by boiling it with alkalies. It con-
sists of flat needles, melting at 115°. Hydriodic acid reduces it to cethylbenzoic
acid (p. 754). It unites with hydroxylamine and phenylhydrazine to form pecu-
liar compounds. Two molecules of water are eliminated (Berichte, 19, 1996).
Trichlor- and Tribrom-acetophenone-Carboxylic Acid,Q.^^(CO.C%.^ C02H,are
produced by the decomposition of the indene derivatives (Berichte, ai, 2396).
The /3?-a-acid is prepared by oxidizing oxyisopropylbenzoic acid with a chromic
acid mixture. It melts at 200°-

4. Propionyl Benzoic Acids, ^^^i,\/^^^ > Propiophenone Carboxylic

Acids. The ortho-ioxm is produced when phthalyl propionic acid is boiled with
alkalies. It melts at 58°. Hydriodic acid reduces it to o-propylbenzoic acid.

DIBASIC KETONIC ACIDS. 765

Diketonic Acids.

Benzoyl Glyoxylic Acid, CjHj.CO.CO.COjH. Its a-hydrazone is derived
from benzoylacetic ester and diazobenzene chloride (p. 763).

Benzoyl Pyroracemic Acid, CsH5.CO.CH2.CO.CO2H + HjO, is produced
from acetophenone and oxalic ester (p. 761). It melts at 43°. Ferric chloride
imparts a blood-red color to it. The free acid melts about 157° with evolution of
carbon dioxide, and is colored a deep blue by ferric chloride. Phenylhydrazine
converts the ester into a pyrazole derivative {Berichte, 21, 1131).

When benzoyl chloride acts upon acetoacetic ester and benzoyl acetic ester it
produces benzoyl acetoacetic ester, CgH5.CO.CH.(CO.CH3).COjR and dihenzoyl-
acetic ester, (C5H5.CO)2.CH.C02R. The former decomposes into acetophenone
and benzoyl acetone (p. 731), while the latter yields acetophenone, benzoic acid
and dibenzoyl methane, (CgH^.COjjCHj, melting at 81° and boiling beyond 200°.

Bromacetophenone (p. 728) and acetoacetic ester yield Acetophenone (Phenacyl)-

acetoacetic Ester, ^ tt cc\CY{ /CH.COjR.

This decomposes into acetophenone acetone, but by condensation (as a j-dike-
tone) forms methyl phenyl-furfurane carboxylic acid (p. 527). In the same manner

benzoyl acetic ester yie\6s phenacyl-beneoylacetic ester, „ „ (-'(-, ^rr ^ CH.CO.^R,

which by decomposition forms benzoyl-propionic acid (p. 764) and dlphenacyl,

(CsH5.CO.CH2)2 (p. 731), and by condensation yields diphenyl-furfurane car-

boxyhc acid (p. 524) [Berichte, 21, 3053).

/CO CO CO H
Quinisatinic Acid, C-H^^ -^t^ ' ^ , 0 amido-phenyl mesoxalylic acid.

It is obtained by oxidizing dioxycarbostyril with ferric chloride. From water it
crystallizes in yellow prisms. Heated to 120° it becomes a lactime — quiaisatin,

,CO.CO.
*--6^4\^ ^C.OH This is analogous to the formation of isalin from isatinic

acid (Berichte, 17, 985).

Diphenacylaceto-acetic Acid, (CeH5.CO.CH2)2C.(CO.CH3).C02H {Be-
richte, 22, 3225), is a triketonic acid.

Dibasic Ketonic Acids.

Benzoyl chloride converts malonic esters into —

Benzoyl Malonic Ester, C6H5.CO.CH(C02R)2 {Berichte, 20, Ref. 381).
Its o-KzVro-compound (obtained with o-nitrobenzoyl chloride) yields quinoline de-
rivatives when reduced {Berichte, 22, 386).

Benzoyl-isosuccinic Ester, CeH5.CO.CH2.CH(C02R)2 {Berichte, 19, 95),
is obtained from bromacetophenone and malonic ester. The free acid melts at
1 80°, decomposing at the same time into carbon dioxide and benzoyl propionic
acid (p. 764).

a-Carbophenyl glyoxylic Acid, ^a^^Cq^q Yi ^ ' '^ ^o^"^^^ by oxidizing
hydrindene carboxylic acid and also a-naphthol with potassium permanganate
{Berichte, 21, 1609). It is very readily soluble in water, melts at 140°, and de-
composes into carbon dioxide and phthalic anhydride. Sodium amalgam reduces
it to an oxy-acid, which immediately changes to its lactonic acid — phthalide car-
boxylic acid (p. 772) : —

„ „ /CH(0H).C02H _ c H /Ch/S°^\ H O

766 ORGANIC CHEMISTRY.

»-Carbobenzoyl Acetic Acid, C^B.y^'^'-^^^^, Benzoyl aceto-car-

boxylic acid. This acid is formed when phthalyl acetic acid is dissolved in alka-
lies. It crystallizes in brilliant needles, melting at 90°, with decomposition into
carbon dioxide and «-acetobenzoic acid (p. 764). When this acid is dissolved in
sulphuric acid and precipitated with water it reverts again to phthalyl acetie acid;
a ketonic acid is transposed into a lactone (p. 352) [Berichte, 17, 2619) : —

ConsMlt Berichte, 17, 2665; 19, 3144 for different diketone-dicarboxylic acids.

MONOBASIC OXY-ACIDS.

The aromatic oxy-acids containing hydroxyl united to the ben-
zene nucleus, e. g., QHi.OH.COaH, combine the character of
acids and phenols, hence are designated Phenol acids. Should the
hydroxyl groups enter the side-chains, we would obtain aromatic
oxy-acids (alcohol acids), corresponding in all particulars to the
oxy-fatty acids.

The phenol-acids are produced : —

1. From the benzene carboxylic acids by methods analogous to
those used in the preparation of the phenols from the benzenes : the
conversion of the araido-acids, by means of nitrous acid, into diazo-
compounds and then boiling the latter with water ; by fusing the
sulphobenzoic acids with alkalies. The haloid benzene carboxylic
acids react like the sulpho-acids when subjected to similar treat-
ment (p. 666) : —

CsH^CLCOaH -f KOH = CsH4(OH).C02H -f KCl.

The homologous phenols become oxy-acids when fused with
alkalies : —

C,H / + 2KOH = CeH / -f 3H„

whereas they are only oxidized by the ordinary oxidizing agents
after the hydroxyl hydrogen has been replaced by alkyls or acid
radicals (p. 686). The oxy-aldehydes that are oxidized with diffi-
culty are readily changed to oxy-acids upon fusion with the
alkalies.

2. The oxy-acids are produced synthetically by the action of
chlorcarbonic esters or carbon dioxide upon the sodium salts of
the phenols (p. 739) : —

C,H,.ONa -f CO, = CeH,/0^^j^^.

ORTHO-OXYBENZOIC ACID. 767

At lower temperatures (below ioo°) phenol carbonates constitute the chief pro-
duct. At more elevated temperatures these are re-arranged into their isomeric
oxy-acids (p. 670). When this occurs the carboxyl-group generally enters the
orMo-position. The polyhydric phenols are often converted into oxy-acids by
•merely heating them together with ammonium or potassium carbonate (p. 739.)

3. A specifically synthetic method for the preparation of oxy-
acids consists in the transposition of phenols by boiling them with
carbon tetrachloride and caustic potash {Berichte, lo, 2185) : —

,0H
C5H5.OH + CCl^ -f sNaOH = CgH^/ + 4Naa + sH^O.

^COjNa

This reaction is perfectly analogous to that of the formation of
oxyaldehydes by means of chloroform (p. 723). As a general
thing the carboxyl-group enters the ortho- or para-position, with
the formation of two isomeric oxy-acids.

Their basicity is determined by the number of carboxyl groups
present, as alkaline carbonates convert them into carboxyl salts.

Their hydroxyl hydrogen can also be replaced by alkalies, forming basic salts,

/ONa
'• S-' '--e^iC cCt ISr • Carbon dioxide, however, will convert the latter into

neutral salts. The ethers or esters manifest a like deportment, inasmuch as it is
only the carboxyl esters that are saponified by alkalies (p. 349) : —

.O.CH3 /O.CH3

C,H / -I- KOH = CeH / -f- CH3.OH.

\cO2.CH3 ^COjK

The ortho-oxy-acids, unlike the meta- and para-derivatives, volatilize in aqueous
vapor, are colored violet by ferric chloride, and dissolve in chloroform. The
meta-oxy-acids are colored reddish brown when heated with concentrated sul-
phuric acid, with the formation of oxyanthraquinones {^Berichte, 18, 2142). They
are usually more stable than the ortho- and para-acids. Boiling concentrated
hydrochloric acid decomposes the para-acids into carbon dioxide and phenols.
Consult Berichte, 18, Ref. 487 for the heat of neutralization of the three oxyben-
zoic acids. All the oxy-acids decompose into carbon dioxide and phenols when
distilled with lime (p. 667).

Alcohol acids (p. 766) are perfectly analogous to the acids of the paraffin series
in their modes of formation and properties.

/CO H
I. Acids, CiHsOs = ^^i\Q)^ > Oxybenzoic Acids.

I. Ortho-oxybenzoicAcid,C6Hi(OH).C02H(i, 2), Salicylic
Acid, occurs in a free condition in the buds of Spirma iilmaria, as
the methyl ester in oil of GauUheria proiumbens (Oil of Winter-
green) and other varieties of gaultheria, from which it may be

■J 68 ORGANIC CHEMISTRY.

easily obtained by saponification with potassium hydroxide. It is
prepared artificially : by oxidizing saligenin and salicylic aldehyde ;
by action of nitrous acid upon anthranilic acid ; from the two
nitro-(i, 3)-brombenzoic acids (p. 748); by fusing orthochlor-
and brombenzoic acids, orthotoluene sulphonic'acid and ortho-
cresol with alkalies ; from phenol with CO^, or with chlorcarbonic
ester and sodium, or by means of CCI4, and sodium hydroxide (p.
767). Its production from COj and sodium phenoxide is especially
interesting. This reaction is employed for its formation upon a
large scale. The acid can be made according to two methods : —

{a) When sodium phenoxide is heated in a current of carbon
dioxide at 180-220°, the latter is absorbed, half of the phenol dis-
tils over, and the residue is disodium salicylate — Kolbe: —

2CeH,.0Na + c6,=C,H,(^^^^^^ + C.H^.OH.

The same reaction occurs when potassium phenoxide is heated to 150° in a
current of carbon dioxide. At a more elevated temperature, however, there is
formed with the dipotassium salicylate its isomeride, dipotassium paraoxybenzoate.
The latter is more abundant in proportipji to the increased temperature, until at
220° it is the sole product. Primarv-'pbtassium salicylate undergoes a similar
transposition at 220° ; phenol then di^ils o^ver and dipotassium paraoxybenzoate
constitutes the residue : — ' ■

zCeH^^^Q^j^ = CgH^^-^Q^j^ + CsHj.OH + CO^.

The sodium salt also decomposes in this manner, but instead of paroxybenzoic
acid it yields disodium salicylate. On the other hand, if we expose primary
sodium paraoxybenzoate, at 280—290°, in a current of COj, there results conversely
(together with phenol) disodium salicylate. This strikingly illustrates the different
deportment of potassium and sodium on fusion {^Jour.pr. Ch. [2], 10, 95 ; 16,
425)-

{!?) Sodium phenoxide is saturated under pressure, in closed ves-
sels, with carbon dioxide, when it is converted into sodium pheno-
carbonate, C6H5.0.C02Na (p. 670). By continuing the pressure
and applying a heat of 120-130°, this salt is changed to sodium
salicylate, C6H4(OH).C02Na. In this manner all the phenol is
converted into salicylic acid (R. Schmitt, Berichte, 18, Ref. 439).

(f) A third procedure less adapted for the production of salicylic acid, consists
in heating phenol carbonate (p. 670) at 200°, with caustic soda. Phenol distils
over and sodium salicylate remains : —

(C5H5.0)2CO -f NaOH = C8Hi(OH).C02Na + CjHj.OH

Salicylic acid consists of four-sided prisms and crystallizes readily
from hot water in long needles. It dissolves in 400 parts water at
15°, and in 12 parts at 100°; it is very soluble in chloroform. It

ORTHO-OXYBENZOIC ACID. 769

melts at 155-156°, and when carefully heated sublimes in needles ;
when quickly heated (or with water at 220°, more readily with
hydrochloric acid) it breaks up into carbon dioxide an4 phenol.
Its aqueous solution acquires a violet coloration upon the addition
of ferric chloride. It is a powerful antiseptic, hence its wide appli-
cation.

When salicylic acid is heated with baryta water, the hydrogen atoms of both
hydroxyls are replaced by barium, and leaflets of the basic salt separate : —

CeH4<^°^Ba + 2H,0. .

~When boiled with lime water the basic calcium salt is precipitated as an insol-
uble powder. This behavior affords a means of separating salicylic from the other
two oxybenzoic acids. The halogens react readily with salicylic acid, yielding
substitution products. Nitration produces three nitrosalicylic acids.

PCI5 converts salicylic acid into the chloride, CjH^Cl.COCI, — an oil, boiling at
240°. Hot water converts it into orthochlorbenzoic acid.

PCI3O produces the so-called salicylide, CjH^^Oj = C^H^c^ ,j ^ (?), which

crystallizes in shining leaflets, melting at 195°- Boiling alkalies change it again
to salicylic acid.

The esters of salicylic acid appear, according to the common method, by con-
ducting hydrochloric acid gas into its alcoholic solutions. The methyl ester,
CgHj(OH).C02.CH3, is the chief ingredient of wintergreen oil (from Gaultheria
procumbens^. It is an agreeably-smelling liquid, which boils at 224° (corrected) ;
its sp. gr. = 1. 197 at o°- It dissolves in alkalies, forming unstable phenol salts.
Ferric chloride gives it a violet coloration. The ethyl ester, CgHj(OH)COj.CjH5,
boils at 223°.

When the methyl ester is digested with an alcoholic soluti.on of potassium
hydroxide and methyl iodide at 120° (p. 670), we get the dimethyl ester,

CjHj.^ P„ JW , which is an oil boiling at 245°. Boiled witli potassium
hydroxide, it is saponified, yielding methyl alcohol and methyl salicylic acid,
'-'6^4\ en 'n'' '"'''i'^^ forms large plates, melting at 98°. It is readily soluble in
hot water and alcohol. It decomposes into carbon dioxide and anisol, C5H5.O.
CHj, when heated to 200°.

We can produce salicylic-dielhyl ester, boiling at 259°, and ethylsalicylic acid
in the same manner. The latter melts at 19.5°, and at 300° decomposes into
carbon dioxide, and ethyl phenol, CgHj.O.CjHj.

Acetyl chloride converts salicylic acid into aceto-salicylic acid, €5114(0. CjHjO).
COjH, which crystallizes in delicate needles, and melts at 218°.

The phenol salicylic esters are the salols, used as antiseptics. They are pro-
duced when POCI3 or PCI 5 acts upon a mixture of salicylic acid and various
phenols. Or phosgene may be allowed to act upon a mixture of the sodium salts.
In this way a great variety of different salols has been obtained {Beriehte, 21, Ref.
554 ; 22, Ref. 309).

Salicylic Phenol Ester, Cfi^{p'H.).CO^.Cfi^, Salol, consists of white crys-
tals, melting at 43°. When sodium salol, Q.^^{01^^).C0^.C^ ^^ (from salol and
sodium), is heated to 28o°-300°, it changes to the isomeric sodium salt ol phenyl-
salicylic acid, Q,^^{p.C^^)XX>^, which melts at 113°, and is -not colored by

770 ORGANIC CHEMISTRY.

ferric chloride {Berichte, 21, 502; 23, Ref. 342). It changes to diphenylene
ketonoxide, C5H^(^P„ JjCgH^ (Xanthone), by the elimination of water (by
means of sulphuric acid, or upon heating with PClj).

2. Meta-oxybenzoic Acid, CjH^^pQ tt (1, 3), is produced: by acting

with nitrous acid upon ordinary (i, 3)-ainidobenzoic acid; by fusing (l, 3).chlor-,
brom-, iodo-, and sulpho-benzoic acids and metacresol with potassium hydroxide.
It also results from metacyanphenol. It usually crystallizes in wart-like masses con-
sisting of microscopic leaflets, dissolves in 260 parts of water at 0°, and readily in
hot water. It melts at 200°, and sublimes without decomposition. Ferric chloride
does not color it. It yields carbon dioxide and phenol when heated with
alkalies. •

The ethyl ester, CgH4(OH).C02.C2H5, crystallizes in plates, soluble in hot
water, and melting at 72°. It boils at 282°. T'az dimethyl ester, C^\i^(0.ai.^.
C02.CHj, is formed when metaox_ybenzoic acid is heated with methyl iodide (2
molecules) and potassium hydroxide (2 molecules) to 140°. Boiling caustic potash
converts this into methyl-metaoxybenzoic acid, Q,^^[(i.CS^^.QO,^. The latter
is also obtained from the methyl ether of metabromphenol, CgH^^Br.O.CHj, with
sodium and carbon dioxide. It crystallizes in shining scales, is easily soluble in
water, melts at 107°, and sublimes undecomposed.

3. Para-oxybenzoic Acid, CgH^^' p^ „ (l, 4), is obtained from parachlor-,

brom-, iodo- and sulpho-benzoic acids, and also from many resins, by fusing
them with potassium hydroxide. It results, too, when para-amidobenzoic acid is
treated with nitrous acid or phenol with carbon tetrachloride and sodium hydroxide
(together with salicylic acid). An interesting way of obtaining it consists in heat-
ing potassium phenoxide in a current of carbon dioxide (p. 768) at 220'''. This is
the best course to pursue in preparing it {Journal pract. Chemie, 16, 36, Berichte,
22, Ref. 622).

Paraoxybenzoic acid crystallizes from water in monoclinic prisms, containing i
molecule of HjO. This it loses at 100°. It is somewhat more easily- soluble than
salicylic acid (in 580 parts H^O at 0°), and melts at 210° with partial decomposi-
tion into carbon dioxide and phenol. Ferric chloride does not color it, but throws
down a yellow precipitate which dissolves in an excess of the reagent. Its basic

barium salt, <Z^/ pj-, ^Ba, is insoluble, and may be employed to separate the

acid from its meta-isomeride.

The methyl ester, CgH^^ „^ „„ , consists of large plates, melting at 17°, and

distilling at 273°. The ethyl ester melts at 113°, and boils near 297°-

Methyl-paraoxybenzoic Add, CjH^/pQ „', and ethyl-faraoxybenzoic acid,
/r\ ("* TT
^e^^-iyCO H *' ™^ prodiiced the same as the corresponding compounSs of the

other two benzoic acids; the second melts at 195°.

Anisic Acid, called methyl paraoxybenzoic acid, is obtained
by oxidizing anisol and anethol (p. 724) with nitric acid or a
chromic acid mixture : —

Anethol. Anisic Acid. Acetic Acid,

ANISIC ACID. 771

or by oxidizing the methyl ether of /-cresol, CJIi( j^V^ . It is

prepared by oxidizing anisol with a chromic acid mixture (Anna/en,
141, 248).

Anisic acid crystallizes from hot water in long needles, from
alcohol in rhombic prisms, melts at 185°, sublimes and boils with-
out decomposition at 280°. Heated with baryta it breaks up into
carbon dioxide and anisol, CsHs.O.CHj. It yields paraoxybenzoic
acid when heated with hydrochloric or hydriodic acid (p. 668).
The salts of anisic acid are very soluble in water and crystallize
well. The halogens and nitric acid afford substitution products.
These yield substituted anisols by distillation with baryta.

Adds, CgHgOs-

1. Oxytoluic Acids, C5H3(CH)3^ P^-. „, Cresotinic Acids. The ten pos-
sible isomerides are known [Berichte, 16, 1966). They result from the totuic
acids, C5Hj.CH3.COOH, by the substitution of OH for one atom of hydrogen in
the benzene nucleus, and from the cresols, C5Hj(CH3).OH, by the introduction of
COjHjby means of sodium and carbon dioxide, or by th^ carbon chloride reaction
(p. 767). They can also be obtained by the oxidation (fusion with caustic alkali) of
their aldehydes, C5H3(CH3)(OH).CHO. The latter are made from the cresols by
means of the chloroform reaction. Those isomerides in which the Oj^" occupies the
ortho place with reference tothe COjH group (4 isomerides) are, like salicylic acid,
colored intensely violet by ferric chloride, are readily soluble in cold chloroform, and
are volatile in steam. When ignited with lime the oxytoluic acids split up into carbon
dioxide, and the corresponding cresols, C5Hj(CH3).OH. Some of them, especially
the ortho-oxyacids, suffer this change when heated with concentrated hydrochloric
acid to 200°. Symmetrical metaoxy-m-toluic acid, yields, by nitration, a trinitro-

product, C((OH)(NOj)3/Sq\t, melting at 180°; this is identical 'with the nitro-
coccic ac/^^ obtained from aloes [Berichte, 18, 251).

2. Oxyphenyl Acetic Acids, CgH^^ „„ /-.q tt, oxy-alphatoluic acids.

The/- and zw-acids can be obtained from the corresponding amidophenyl acetic
acids, CgH,(NH2).CHj.COjH (p. 756), by diazotizing, and also from the oxyben-
zyl cyanides, C5Hj(OH).CH2CN (p. 735-).

0- Oxyphenyl Acetic Acid has been obtained from isatinic acid (andisatin), (p.
762). The diazotizing of isatin at first produces oxyphenylglyoxylic acid, CgH^
(0H).C0.C02H, which by action of sodium amalgam becomes o-oxymandelic acid,
C6H4(OH).CH(OH).C02H. The latter on boiling with hydriodic acid yields 0-
oxy-phenylacetic acid, melting at 137°. Ferric chloride colors it violet. Being a

y-oxyacid it forms a lactone, CsHiy^ r^j^O' ^^^^ distilled, This melts at 49°,

and boils at 236° (Berichte, 17, 975).

m- Oxyphenyl Acetic Acid meUs at 129°. p-Oxyphenyl Acetic Acid occurs in
urine, and arises from the decomposition of albuminous bodies. It crystallizes in
flat needles, melts at 148°, and is colored dirty-green by ferric chloride. When .
distilled with lime it yields carbon dioxide, and/-cresol, CjHi(CH3).0H.

772 ORGANIC CHEMISTRY.

3. Oxymethylbenzoic Acids, C^HjC' j,q2-^ . Mineral acids precipitate the

ortho acid from its salts (obtained by boiling phthalide with alkalies) in the form
of a powder. This melts at 118°, with decomposition into water and phthalide. It
is a 7-oxyacid, hence by the elimination of water can yield a lactone (even by
boiling with water) : —

C TT /CHj.OH (- H •>^^H2\j-, 1 II (-)

*^6"*\CO.OH — ^«"*\C0 /^ + 2

The lactone, C5H5O2, called Phthalide, is jjrepared by the action of hydriodic

acid, or zinc and HCl upon phthalic chloride, CgH4(' (-•oJ!>0 [Berichte, 10,

1445). It also results from orthoxylylene chloride upon boiling with water and
lead nitrate ; by the reduction of phthalic anhydride in acetic acid solution with zinc
dust {^Berichte, 17, 2178) ; by the action of bromine vapor upon orthotoluic acid at
140°, and most easily by digesting phthalidin, CjHjNO (from phthalimide) with
caustic soda [Berichte, 17, 2598). Phthalide resembles the lactones perfectly and
is the first discovered member of that series. It crystallizes from hot water and
alcohol, in needles or plates, melts at 73°, and boils at 290° (c6r.). It is reduced
to orthotoluic acid on boiling with hydriodic acid. Potassium permanganate
oxi4izes it to phthalic acid. Sodium amalgam reduces it to hydrophthalide,

CgH^cf ^Hfn'H^ /*-'■ '^'^^ esters of benzoic acid are similarly reduced [Berichle,
". 239)-

Phthalide yields the base Phthalidin, CgH,NO = CgH^/^^^— ->0, or

^6^4\ pn''^^^' ^l'^" '' '^ heated in an atmosphere of ammonia. Phthalidin
can also be very readily obtained by reducing phthalimide with tin and hydro-
chloric acid. It crystallizes fronj hot water in needles, melting at 150° and dis-
tilling at 337°.

Dialkylphthalides, e.g ,Q,^Yi^<:^^^^^yO, have been obtained by the ac-
tion of zinc and alkyl iodides upon phthalic anhydride [Berichte, 22, Ref. 11).

The potassium salt of cyan-benzyl-o-carboxylic acid = (cyan-o-toluic acid) is
formed when phthalide and potassium cyanide are heated to 180° : —

/CHj^^ , ^T^TTT _ r- tr /CHjCN

C6H4\cO >0 + ^N^ = ^^H,/^^«5

The free acid is a powder that is almost insoluble in water, and melts at 1 16°,
without decomposition {Berichte, 19, Ref. 439).

Other phthalide derivatives worthy of note are phthalide-acetic acid, phenyl-
phthalide, methylene phthalide, benzylidene phthalide, and the phthalides and
phthaleins.

4. Phenylglycollic Acid, Mandelic Acid, C6Hs.CH(0H).
COjH, was first obtained by heating amygdalin (p. 717) with hy-
drochloric acid, and is synthetically formed from benzaldehyde by
the action of prussic acid and hydrochloric acid, and the transfor-
mation of the oxycyanide first produced : —

C5H5.CH(OH).CN + 2H2O = C5H5.CH(OH).C02H + NH^.

PHENYLGLYCOLLIC ACID. 773

It can also be obtained from benzoylformic acid (p. 762), by-
reduction with sodium amalgam, and from phenylchloracetic acid
CP- 754) by boiling it with alkalies, as well as by the action of
alkalies upon dibromacetophenone, CeHs.CO.CHBrj, or phenyl-
glyoxal (p. 730).

Preparation. — Boil the oxycyanides either with concentrated hydrochloric acid
or heat them with sulphuric acid, which has been diluted with one- half volume of
water. Or the oxycyanide can be changed to phenylchloracetic acid by heating
it to 140° with concentrated hydrochloric acid {Berichte, 14, 239). The oxycyanide,
CeHs CH(OH).CN, is obtained by digesting benzaldehyde for some time with 20
per cent, prussic acid (p. 347), or by gradually adding concentrated hydrochloric
acid (i molecule), with constant stirring, to a cooled mixture of benzaldehyde with
ether and pulverized CNK (i molecule). — Berichte, 14, 239 and 1965. The oxy-
cyanide is a yellow oil with an odor resembling that of prussic acid and oil of
bitter almonds. It solidifies at — 10°, and decomposes when heated.

The natural mandelic acid, obtained from amygdalin, is optically
active, and, indeed, Isevo-rotatory. It forms brilliant crystals,
melting at 132.8°. Synthetic-rnandelic acid, called paramandelic
acid, is optically inactive; it crystallizes in rhombic plates or
prisms, and melts at 118°. It is more soluble in water than the
Isevo-acid (100 parts water at 20° dissolve 15.9 parts of the former
and 8.6 parts of the latter). Both acids manifest like chemical
deportment (like the tartaric acids, etc.). Dilute nitric acid con-
verts them into benzoyl-formic acid, while by more powerful oxi-
dation, they yield benzoic acid. When heated with hydriodic acid
they form phenyl-acetic acid, with hydrobromic and hydrochloric
acid chlorphenyl or bromphenyl acetic acids.

Inactive or paramandelic acid, like racemic acid, consists oi dextro- and lavo-
mandelic acids (p. 64). Fermentation with Penicillium glaucum destroys the
Isevo and there remains the dextro-acid, which, so far as physical properties are
concerned, resembles the so-called natural Isevo-acid perfectly, only excepting the
fact that the former rotates the plane equally as much to the right. Lasvo-
mandelic acid, however, is formed from the para-acid through the influence of a
schizomycetes (Vibrio?) {Berichte, 17, 2723). The direct splitting up of para-
mandelic acid into the dextro- and Isevo-acids can be brought about by the crystal-
lization of the cinchonine salt. The mixing together of the dextro- and Isevo-acids
(molecular quantities) results in the formation of inactive paramandelic acid.
When the dextro- or Issvoacid is heated in a tube to 160° it is converted into the
inactive mandelic acid.

Nitro-mandelic Acids.

«-Nitro-mandelic Acid, C5H^(NOj).CH(OH).C02H, is produced (analogous
to mandelic acid) by dissolving o-nitro-acetophenone-dibromide, C5H^(N02).CO.
CHBr2, in caustic potash. It melts at 140°. When reduced with tin and hydro-
chloric acid it yields o-amido-mandelic acid, i. e., dioxinol (see below) (Berichte,
20, 2203).

OT-Nitro-mandelic Acid is obtained from »«-nitrobenzaldehyde.

Amido-mandelic Acids.

o-Amido-mandelic Acid, C^H^^^'^^^^^^-'^^^^, Hydriudic Acid. Its

774 ORGANIC CHEMISTRY.

sodium salt is formed from isatin by the action of sodium amalgam, and separates
from the concentrated solution in brilliant crystals, CjHjNaNOj + H^O. This
is not stable in a free condition, but immediately passes into its lactam, dioxindol,
by the splitting-off of water (p. 755) : —

^CH.OH.COjH ,CH(OH),

C,H,^ = C,H / >CO + H,0.

A more stable compound than the preceding is Aceto-ff-amidomandelic

Acid, CgHj^^TT^pL h„ 2 . This is obtained from aceto-isatinic acid (p. 762)

by the action of NaHg, and from aceto-dioxindol by its solution in baryta water.
It is very soluble in water, crystallizes in needles, and melts at 142°. The action
of hydriodic acid or sodium amalgam causes it to break up into acetic acid and
oxindol, the anhydride of o-amido-phenyl acetic acid (p. 756).

3. Acids, C^HjjOj.

1. Oxyethylbenzoic Acid, C„H /^q (^^^'^^3 (ortho), is formed from

acetophenone-carboxylic acid (p. 764) when treated with sodium amalgam. It
yields a lactone which solidifies below 0° [Berichte, 10, 2205).

2. Oxymesitylenic Acid, C^U^iCW.^)^^^ ^ (COjH:OH = 1:2), is ob-
tained by fusing mesitylene sulphonic acid with caustic alkali, and when nitrous
acid acts upon amidomesitylenic acid. It melts at 179°, and being an oxyacid is
colored a deep blue by ferric chloride.

3. Oxyphenylpropionic Acids, C5Hj(^^tj pn h" There are six isomerides.

o-Hydro-coumaric Acid, Melilotic Acid, CgH^^pTr prr rr\-a ('> 2),

occurs free and in combination with coumarin in the yellow melilot (Melilotus
officinalis), and is produced by the action of sodium amalgam upon coumaric acid
and coumaria (see this) : —

C.HeO, + H,0 + H, = C,Hi„03.

Coumarin.

It crystallizes in long needles, dissolves easily in hot water, and melts at 81°.
Ferric chloride imparts a bluish color to the solution. When distilled it passes

into the ^-lactone, CjHgOj = CgH^^^ ^^, Hydrocoumarin, melting at

25°, and boiling at 272°. When boiled with water it regenerates the acid. Meli-
lotic acid decomposes when fused with alkali into salicylic acid and acetic acid ;
hence it is a benzene derivative of the ortho-series. Ethyl Melilotic Acid, CgHj
{O.C^^SZ^^.CO^, is produced by ethylating the acid and when sodium
amalgam acts upon ethyl coumaric and ethyl coumarinic acids ; it melts at 80°.

?»-Hydro-coumaric Acid, CjH/yj; „„ /-./-, tt (i, 3), is obtained from
meta-coumaric acid by means of sodium amalgam ; it melts at 1 11°.

/-Hydro-coumaric Acid, C^H^-^yrr q^, ^q tt (i, 4), results when
sodium amalgam acts upon para-coumaric acid, or when nitrous acid acts an

TYROSINE. 775

/-atnidohydrocinnamic acid (p. 758), and in the decay of tyrosine. It is very
soluble in hot water, forms small crystals, and melts at 128° (Berichte, 17, Ref.
433)-

One of the amido-derivatives of/-hydro-coumaric acid is

Tyrosine, QH.NO^ = CeH,((.jj^^jj^j^jj^^^^Q^jj (i, 4),

Oxyphenyl-a-amidopropionic Acid, Oxyphenyl-alanine. It occurs
in the liver, the spleen, the pancreas, and in stale cheese {rupbb),
and is formed from animal substances, (albumen, horn, hair) on
boiling them with hydrochloric or sulphuric acid ; by fusion with
alkalies or by putrefaction (together with leucine, aspartic acid,
etc.). It may be prepared synthetically from /-amido-phenyl-
alanine (from phenylacetaldehyde, p. 758) by the action of i mole-
cule of potassium nitrite upon the hydrochloric acid salt. It is
soluble in 150 parts boiling water, and crystallizes in delicate, silky
needles ; it dissolves with difficulty in alcohol, and is insoluble in
ether.

Mercuric nitrate produces a yellow precipitate, which becomes dark red in color
if it be boiled with fuming nitric acid to which considerable water has been added
(delicate reaction). Being an amido-acid, tyrosine unites with acids and bases,
forming salts. If it be heated to 270° it decomposes into carbon dioxide and oxy-
phenylethylamine, CgH4(OH).CHj.CH2.NH2. When fused with caustic potash it
yields paraoxybenzoic acid, ammonia and acetic acid. Putrefaction causes the
formation of hydroparacoumaric acid, and nitrous acid converts the tyrosine into
para-oxyphenyl-lactic acid, CgH4(OH).CH2.CH(OH).C02H (Annalen, 219,
226).

Phloretic Acid, C^Hj^ ^ „ pQ ti (i, 4), oxyphenyl-a-propionic acid, is

formed together with phloroglucin when phloretine is digested with potassium
hydroxide (p. 695). It crystallizes in long prisms, is very soluble in hot water,
and melts at 128-130°- Ferric chloride colors its solution green. Baryta decom-
poses it into carbon dioxide and ethyl phenol ; fusion with potassium hydroxide
produces paraoxybenzoic and acetic acids. The oxidation of methyl phloretic
acid yields anisic acid. Phloretic acid, like the cresols, cannot be directly oxid-
ized (p. 686).

4. Phenyloxypropionic Acids, C5Hg.C2H3(OH).C02H. There are four
isomerides : —

I. C,H,.C(0H)(CH3^ 2. C,H,.Ch/^H3X)H

a-Phenyl-lactic Acid, a-Phenyl-hydracrylic Acid,

Atrolactinic Acid. Tropic Acid.

3. C6H5.CH2.CH(OH).C02H 4. CsH5.CH(OH).CH2.C02H.

^-Phenyl-lactic Acid, i3-Phenyl-hydracrylic Acid.

(l) The so-called Atrolactinic Acid is obtained from a-bromhydro-atropic acid
(p. 759), when the latter is boiled with a soda solution, and by oxidizing hydro-
atropic acid with potassium permanganate. It is prepared synthetically from
acetophenone, CjH5.CO.CH3, by means of prussic acid and sulphuric acid or
dilute hydrochloric acid, and by boiling the cyanide with concentrated hydrochloric
acid we get ^-Chlorhydro-atropic Acid (p. 759) [Berichte, 14, 1352 and 1980).

776 ORGANIC CHEMISTRY.

It dissolves very readily in water, crystallizes with one-half molecule of water in
needles or plates, and at 80-85° l°s^s ''^ water of crystallization. While yet con-
taining water it melts at 91° ; when anhydrous at 93°. It remains unaltered when
heated with baryta water, but when boiled with concentrated hydrochloric acid, it
decomposes into water and atropic acid.

(2) Tropic Acid is obtained by digesting the alkaloids, atropine and belladonna,
with baryta water. It is formed artificially, by boiling ;3-chlorhydro-atropic acid
(p. 759), with a solution of potassium carbonate [Annalen, 2og, 25). The acid
dissolves with more difficulty in water ; crystallizes in needles or plates, and melts
at 117°. It is inactive, but can be resolved into a lavo- and dextro-iorra by the
crystallization of its quinine salt. The dextro-variety crystallizes in bright vitreous
prisms and leaflets; it melts at 128°. The Isevo-form melts about 123° [BericAte,
22, 2590). It decomposes into water and atropic acid when boiled with baryta
water.

(3) ^-Phenyl-lactic Acid, C6H5.CH2.CH.(OH).COjH, Benzyl-glycollic acid,
is derived from phenylacetaldehyde (p. 721), with prussic acid and hydrochloric
acid, and from benzyl-tartronic acid upon heating it to 180°. The acid crystallizes
from water in large prisms, melts at 97°, and when heated to 130° with dilute sul-
phuric acid decomposes into phenylacetaldehyde and formic acid. Boiling water
does not alter it.

(4) /3-Phenyl-hydracrylic Acid, CjH5.CH(OH).CH2.C02H, commonly called
phenyllactic acid, results on boiling ;3-brom-hydro-cinnamic acid (p. 757) with
water, or by the addition of hypochlorous acid to cinnamic acid : —

CsH^.CHiCH.CO^H + ClOH = C(.H5.CH(0H).CHC1.C02H,

and then reducing the resulting chlor-acid with sodium amalgam. The acid is
very soluble in cold water, and melts at 94°. When heated with dilute sulphuric
acid it decomposes (like the /3-oxy-acids) at 100° into water and cinnamic acid
(together with a little styrolene) (Berichte, 13, 304). When digested with the
haloid acids it forms phenyl-,S-haloid-propionic acids (p. 758).
Phenyl-halogen-lactic acids (p. 359) : —

C5H5.CH(OH).CHC1.C02H and CeH5.CHBr.CH(0H).C0^H.

Phenyl-d-chlorlactic acid, Phenyl-j3-brom-lactic acid.

The first of these is produced by the action of chlorine in alkaline solution
upon phenyl-acrylic acid (cinnamic acid) (see above, and aXio Annalen, 219, 184).
It crystallizes with one molecule of water, which escapes in the dessicator. When
it contains water it melts at 79°, when anhydrous at 104°. Phenyl-a-bromlactic
Acid is produced on boiling cinnamic dibromide (p. 757) with water. It crystal-
lizes in leaflets, containing 1H2O, melts at 121°, loses water of crystallization, and
then melts at 125°. When boiled with alkalies both acids yield phenylacetalde-
hyde (p. 721), together with ^Sphenylglyceric acid (see Annalen, 2ig, 180).

Phenyl-;8-bronn-lactic Acid (see above) is produced when hydrobromic acid
acts upon j8-phenylglyceric acid (p. 782). It has not been further described (Be-
richie, 16, 2820).

Nitro-phenyl-lactic Acids, CgH^(N02).CH(OH).CH2.C02H.

The three isomerides (ortho, meta and para) are obtained from the three nitro-
cinnamic acids by the addition of hydrogen bromide, and by the action of the al-
kalies, when their ^-lactones (p. 353) — in the cold — are also produced, C5H4(NOj).

CH^ yCO (Berichte, 16, 2209, 17, 595).

The ortho nitroacid results further by the condensation of o-nitro-benzaldehyde
with acetaldehyde by means of a little bartya water, and by oxidizing the aldehyde

PHENYL-OXYACRYLIC ACIDS. ■ 777

first produced with silver oxide [Berichte, i6, 2206). It melts at 126°, and when
heated to 190° with dilute sulphuric acid yields o-nitro-cinnamic acid. Its /3-lac-
tone melts at 124°, and decomposes on boiling with water into carbon dioxide and
tf-nitrostyrolene; it yields oxydihydrocarbostyril when reduced [Berichte, 17,
201 1 ).

The meta-nitro-acid melts at 105°; its ;8-lactone at 98°. The para-nitro-acid,
obtained by oxidizing ^-nilro-cinnamic aldehyde with argentic oxide, melts at
132°, and its lactone at 92°. When the three nitro acids are heated with alco~
holic zinc chloride, we do not get their lactones, but their esters (Berichte, 17,
1659).

Two phenyl-oxyacrylic acids, or oxy-cinnamic acids, have been prepared
by the action of alcoholic potash upon phenylchlor- and brom-lactic acids (^Be-
richte, 16, 2815) : —

C5H5.CH:C(OH).C02H and CeH5.C{OH):CH.CO,H.
Phenyl-a-oxyaci-ylic Acid. Phenyl-^-oxyacrylic Acid.

One, at least, of these acids represents Phenylglycidic a«'(/, CgH5.CH.CH.CO2H
{^Berichte, 20, 2465). \ |

The nitrophenyl-glycidic acids (p. 456), obtained by saponifying the nitro-
phenylchlor-lactic acids with alcoholic potash, have been studied more fully : —

C,H,.(N02).CH(0H) CsH4(N02).CH.Cl CeH^(N02).CH

I I I >o.

CHCl and CH.OH yield CH

I I I

COjH CO2H CO^H

Nitrophenyl-a-chlorlactic Nitrophenyl-)3 chlorlactic Nitrophenyl-glycidic

Acid. Acid. Acid.

/"ara-nitrophenylglycidic acid melts at 280° with decomposition. It unites with
hydrochloric acid to /-nitrophenyl-/3 chlorlactic acid, which, like the o-acid, melts
at 167-168°. Alcoholic potash again changes it to glycidic acid. Sulphuric acid
■ and water convert glycidic acid into/-nitrophenyl-glyceric acid.

Or^/zo-nitrophenyl glycidic acid, from o-nitrocinnamic acid (Berich/e, 13, 2262),
contains one molecule of water and melts at 94° When anhydrous, it melts at
108°. It combines with hydrochloric acid to (;-nitrophenyl-/3-chIorlactic acid,
melting at 126°. Alcoholic potash regenerates glycidic acid ( Berichte, 19, 2649).
Anthranil and anthroxaualdehyde result when o-nitroglycidic acid is boiled with
water.

1. Phenyl-y-oxybutyric Acid, CgH5.CH(OH).CH2.CH2.C02H, is precipitated
in the cold, from its salts, by hydrochloric acid. It melts at 75°, with decomposi-
tion into water and its lactone — phenyl-butyrolactone, CioHnjOj. The latter
is obtained from phenyl-brombutyric acid (from isophenylcrotonic acid) with a
soda solution. It melts at 37°, and boils at 306° [Annalen, 216, 103).

2. Propyloxybenzoic Acids, C5H3(0H)^^^ jj. Six of the twenty possible
isomerides, having this formula (normal propyl and isopropyl), are known.

3. Oxyisopropylbenzoic Acid, CgH^^^^I^ jj ''^ sls^ oxycuraic acid, is ob-
tained from cumic acid (p. 760), by the hydroxylation of the isopropyl group.

65

■j-jS ORGANIC CHEMISTRY-.

This is effected by the oxidation with potassium permanganate (p. 346). It crys-
tallizes from hot water in thin prisms, and melts at 156°. Its sulpho-acid is simi-
larly formed from paracymene and paraisocymene-sulphonic acid (p. 522) with
potassium permanganate. When boiled with hydrochloric acid it parts with water,and
becomes Propenylbenzoic Acid, C(,H^:f^^ jj^;- 2, which melts at 161°.

Similarly, nitrocumic acid yields Nitro-oxypropylbenzoic Acid, and Nitro-
propenylbenzoic Acid, and by the reduction of the latter, the amic/o acids.
Amido-oxypropylbenzoic acid yields \he cumazonic coTapoxmAs{Berichte, 16,2577,
17,1 303), which are analogous in constitution to the ethenyl-araido-phenols (p. 683).
With nitrous acid amido-oxypropenyl benzoic acid affords methyl-cinnolinecar-
boxylic acid [Berichte, 17, 724).

MONOBASIC DIOXYACIDS.

I. Dioxybenzoic Acids, CjHsOi ^= C6H3.{OH)2.C02H- These
are also termed the carboxylic acids of the corresponding dioxy-
benzenes, C^^iO^^^ (Resorcinol, pyrocatechin, hydroquinone),
since they can be obtained from the latter by the direct introduc-
tion of carboxyl (on heating with ammonium carbonate or potas-
sium carbonate, p. 767), or by the oxidation of the corresponding
aldehydes, C6H3(0H)2.CH0 (p. 723). Three of the six possible
isomerides are derived from resorcinol (i, 3), two from pyrocate-
chin (i, 2), and one from hydroquinone (i, 4). Conversely, by the
elimination of carbon dioxide from the acids we regenerate the
dioxybenzenes.

(1) Symmetrical Dioxbenzoic Acid (l, 3, 5), a-resorcylic acid, corresponding
to orcinol, is obtained from a-disulphobenzoic acid (p. 692) on fusion with potas-
sium hydroxide. It crystallizes with l^HjO, melts at 233°, and by the exit of
carbon dioxide yields resorcinol. Ferric chloride does not color it. When dis-
tilled or heated with sulphuric acid to 130° it yields anthrachrysone, a derivative
of anthracene. Its dimethyl ether, CgH3(O.CH3)2.C02H, is produced on oxid-
izing dimethylorcin, and melts at 176°.

(2) ^-Resorcylic Acid (l, 2, 4 — COjH in l) is obtained on heating resor-
cinol with potassium carbonate [^Berichte, 18, I985), also on fusing ^-disulpho-
benzoic acid and /3-resorcylaldehyde (also umbelliferon) with caustic potash. It
dissolves with difficulty in cold water, crystallizes with I^, 2^ and 3 molecules
of water in fine needles, melting in the anhydrous state at 213°, and decomposing
into CO2 and resorcin. Ferric chloride colors it a dark red. Peonol is a derivative
of /3-resorcylic acid (Serichte, ig, 1777).

(3) y-Resorcylic Acid (l, 2, 6 — CO2H in l) is formed together with ^-
resorcylic acid from resorcinol, by means of ammonium carbonate {BericAte, 13,
2380) ; it decomposes about 150° into CO^ and resorcinol, and is colored a blue-
violet by ferric chloride. On warming it reduces alkaline copper and silver solu-
tions.

(4) Hydroquinone Carboxylic Acid (i, 4, COjH), Oxysalicylic Acid,vi3S
first prepared from gentisin, hence called gentisinic acid. It is obtained from
brom-, ^-iodo-, and amido-salicylic acids; also from hydroquinone by means of a
potassium dicarbonate solution, and by fusing gentisinic aldehyde (from hydroqui-
none with potassium hydroxide [Berichte, 14, 1988). It melts at zoo°, and at

PROTOCATECHUIC ACID. 779

215° breaks up into carbon dioxide and hydroquinone. Ferric chloride colors it
a deep blue. On warming it reduces alkaline copper and ammoniacal silver solu-
tions. When oxidized it yields a yellow-colored acid, which is decolorized by
reducing agents, and is in all probability quinone carboxylic acid, €5113(02).
COjH.

(5) Pyrocatechin-ortho-carboxylic Acid (i, 2, 3 — COj in l) is obtained
from ff2-iodo-salicylic acid by fusion with KOH, and from pyrocatechin on heating
with ammonium carbonate to 140° (together with protocatechuicacid). It crystal-
lizes in small needles (with 2H2O), is colored an intense blue by ferric chloride,
melts at 204°, and decomposes further into carbon dioxide and pyrocatechin
{Annalen, 220, 117).

(6) Protocatechuic Acid, QHsj^o^' ^^' 3' 4— CO^H in
i), Pyrocatechin-para-carboxylic acid, is obtained from many ben-
zene tri-derivatives {,e.g., brom- and iodo-para-oxybenzoic acids,
bromanisic acid, para- and meta-cresolsulphonic acid, eugenol,
catechin), as well as from various resins (benzoin, asafoetida, myrrh)
on fusion with potassium hydroxide (and usually together with
some paraoxybenzoic acid) ; furthermore, on heating hydroquinone
with ammonium carbonate (together with pyrocatechin ortho-
carboxylic acid) and by the action of bromine upon quinic acid.
It is most easily prepared from kino by adding the latter to fused
caustic soda {Annalen, 177, 188). It crystallizes with one mole-
cule of water in shining needles or leaflets, and dissolves readily in
hot water, alcohol and ether. At 100° it loses its water of crystalli-
zation, melts at 199°, and decomposes further into carbon dioxide
and pyrocatechin. Ferric chloride colors the solution green ; after
the addition of a very dilute soda solution it becomes blue, later
red (all derivatives containing the protocatechuic residue, (0H)2C —
Berichte, 14, 958, react similarly). Ferrous salts color its salt solu-
tions violet. It reduces an ammoniacal silver solution, but not an
alkaline copper solution.

Diprotocatechuic Acid, Cj^HjoG,, is a tannic acid, which results on boiling the
preceding with aqueous arsenic acid. It is very similar to common tannic acid,
but is colored green by ferric oxide.

The dimethyl- and diethyl-protocatechuic acids are obtained by heating with
potassium hydroxide and methyl or ethyl iodide.

'f ro PIT ^

Dimethyl -protocatechuic Acid, CjHj X L^ „ ^''^, also results from dimethyl-

protocatechuic aldehyde (p. 726), methyl creosol (p. 693) and methyl eugenol, on
oxidation with potassium permanganate. It is the so-called veratric acid,
CgHiijO^, which occurs together with veratrin (see the alkaloids) in the sabadilla
seeds (from Veratrum Sabadilla). It crystallizes from hot water in needles,
melting at 179.5°. Heated to 150° with hydrochloric acid, it splits off a methyl
group and yields the two monomethyl compounds. When digested with
lime or baryta it decomposes into carbon dioxide and dimethyl-pyrocatechin
(p. 690).

Diethylprotocatechuic acid melts at 149°

780 ORGANIC CHEMISTRY.

Monomsthyl-protocatechuic Acids, CgHgO^ : —

(I) fCO,H (I)

(I)

fCO.H (I) fCO.H (I)

J0.CH3(3) and (2) CeHj^OH (3).

I OH (4) l0.CH3(4)

The first body is vanillic acid, obtained by the energetic oxidation of its alde-
hyde, vanillin (and from coniferine, p. 725), also from aceteugenol, acetferulic
acid, and from aceto-homovanillic acid when oxidized with potassium permanga-
nate (p. 781). It crystallizes from hot water in shining needles, melts at 211°,
and can be sublimed. When it is heated to 150° with hydrochloric acid it decom-
poses into methyl chloride and protocatechuic acid; distilled with lime it yields
guaiacol. When methylated it is converted into dimethyl-protocatechuic acid,
from which it is again regained by a partial demethylation.

Isomeric monomethyl-protocatechuic acid (Formula 2), — Isovanillic Acid, —
was first obtained from hemipinic acid, and is prepared together with vanillic acid
by methylating protocjitechuic acid, or by demethylating dimethyl-protocatechuic
acid, and by oxidizing hesperitinic acid. It melts at 250°.

Coniferyl alcohol (p. 725), eugenol and ferulic acid, stand in close relation to
vanillic acid ; they contain unsaturated side-chains, and, therefore, are treated in
connection with the cinnamic acid derivatives. Meconine, opianic acid and hemi-
pinic acid bear close genetic relation.

The methylene ether of protocatechuic acid is

Piperonylic Acid, CgHjO^ = CjHj^ ('q^CHjJ.CO^H, Methylene-proto-cate-

chuic acid, which is formed upon oxidizing its aldehyde, piperonal (p. 725), and
safrol with potassium permanganate. It is prepared synthetically by heating
protocatechuic acid with methylene iodide and potassium hydroxide, and can be
decomposed conversely into protocatechuic acid and carbon on heating with hydro-
chloric acid. It sublimes in fine needles, melting at 228°, and is soluble with dif-
ficulty in hot water. Heated to 210° with water it breaks up into pyrocatechin,
carbon dioxide and carbon.

Ethylene-protocatechuic acid is a perfect analogue of piperonylic acid. It is
prepared by means of ethylene bromide, and melts at 133°.

Ether derivatives of protocatechuic acid and the trivalent phenol, phloroglucin
(p. 695), are: — Luteolin, Maclurin, and Catechin. The first, CjjHjjOj,
occurs in Reseda luteola and crystallizes in yellow needles. Ferric chloride colors
it green. When fused with potassium hydroxide it is resolved into protocatechuic
acid and phloroglucin : —

Cz„H,,0, + 3H,0 = 2C,H,0, -F CeH3(OH)3.

The second and third bodies are generally included among the tannic acids.
They also are decomposed into protocatechuic acid and phloroglucin on fusion
with potassium hydroxide.

2. Acids, CjHjO^.

(a) Dioxyphenyl-acetic Acids, CgH3(OH)j.CH2.C02H-

I. Homoprotocatechuic Acid and Homovanillic Acid, its monomethyl
ether, have their side-groups occupying the same positions as those of protocate-
chuic and vanillinic acids : —

fCH2.CO2H(0 fCH^.CO.H (I).

C6H3 OH {i\ and C,H3J0.CH3 (3).

I OH (4) I OH (4)

DIOXYTOLUIC ACIDS. 781

The latter is produced, along with vanillic acid, by the. careful oxidation of acet-
eugenol, €51^3(03115) ■( „'p -A q, and the saponification of the acetyl deriva-
tive produced at first. It melts at 143°, and when heated with hydrochloric acid
to 180° yields homo-protocatechuic acid, melting at 127°, and methyl chloride.
Homopyrocatechin is produced when it is heated with lime.

2. Symmetrical Dioxyphenyl-acetic Acid (i, 3, 5).

The trielhyl ester, obtained from the dicarboxylic acid derived from this acid, is
produced by the condensation of acetone dicarboxylic ester(p. 566). It melts at
98° and yields dioxyphenyl-acetic acid upon saponification (two molecules of car-
bon dioxide are eliminated at the same time). The add is soluble in water, alco-
hol and ether. It crystallizes with one molecule of water and melts at 54°. It
resembles orcin in its reactions, and yields the latter when its silver salt is heated
{Berichte, 19, 1449).

(b) Dioxytoluic Acids, C6H2(OH)2/^q s^.

There are five isomerides. Of these orsellic or lecanoric acid, CigHi^O, +
HjO, is found in different mosses of the varieties Roccella and Lecanora. It can
be extracted from the same by means of ether or milk of lime. Its crystals are
almost perfectly insoluble in water, melt at 153°, and are colored red by ferric
chloride. Boiling with lime changes it to orsellinic acid, CgHgOi. The latter
consists of easily soluble prisms, and is colored violet by ferric chloride. It melts
at 176°, and decomposes into carbon dioxide and orcin, C5H3(CH3)(OH)2 (p. 692).

Erythrin, CjoH^jOu (Erythrinic Acid), is an ether-like derivative of orsel-
linic acid and erythrite, CjH5(0H)^ (p. 474). It occurs in the lichen Roccella
fusciformis, which is applied in (he manufacture of archil (p. 693) and is extracted
from it by means of milk of lime. Erythrin crystallizes with i ^ molecules of
H2O and is soluble with difiicultly in hot water. Exposure to the air causes it to
assume a red color. When it is boiled with water or baryta-water it breaks up
into orsellinic acid and picroerythrin : —

C^oHa^Oio + H^O = CsH,04 + Ci^Hi.O,.

Picro-erythrin, CijHjgOj + H^O, forms crystals, which dissolve readily in
alcohol and ether, and on further boiling with baryta water yield erythrite, orcin
and carbon dioxide : —

CizHieO, -f H,0 = C,Hi„0, + CjH.O^ + CO^.

The structure of the preceding compounds is as follows : —

C H fCH \ [ (O^^) /C,H2(CH3) {

Orsellinic Acid. >-6 "2l>"-"s; \ QQM

Orsellic Acid.
Diorsellinic Acid.

.C,H,(0'H)3
,C,H,(0H)3 0(

0/ /OH \C,H2(CH3).C02H

\C,H„(CH3)/ 0( .OH

''\C0,H \CeH2(CH3)(

Picroerythrin. LUgxl

Erythro-orsellinic Ether. Erythrin.

Erythro-diorsellinic Ether,

782 ORGANIC CHEMISTRY.

3. Acids, C9Hj|j04.

Hydro-umbellic Acid, C5H3(OH)2.CHj.CH2.COjH (i, 2, 4 — CH^ in i).
The position of its side-chains is the same as in /3-resorcylic acid (p. 778). It is
obtained from umbellic acid, C^HgO^, and umbelliferon, C5H5O3 (see this), by
the action of sodium amalgam. Above 1 10° it decomposes, water separating, and
melts at 120°. Ferric chloride colors it green. It reduces alkaline copper and
silver solutions. It yields resorcinol on fusion with KOH.

Hydrocaffeic Acid, CgHjjO^.

CjHjJOH (3 C,H3.^0.CH3 C,H3 OH

(.OH (4) (oh (0.CH3

Hydrocaffeic Acid. Hydroferulic Acid. Isohydroferulic Acid.

The hydrocaffeic acid, with the same arrangerhent of side-chains as in proto-
catechuic acid, is obtained from caffeic acid by the action of sodium amalgam ;
is colored the same by ferric chloride, etc., as the protocatechuic acid (779), and
reduces both alkaline copper and silver solutions. Hydroferulic and Isohydro-
ferulic Acids are its monomethyl ethers. They correspond to vanillic and iso-
vanillic acids. Sodium amalgam converts ferulic and isoferulic acids into the
above hydro-acids. The former melts at 90°, the latter at 147°.

Everninic Acid, CglljoOj, is produced, together with orsellinic acid, on boil-
ing evernic acid, CijHjjO, (from Evernia Prunastri), with baryta. It melts at
157°, and is colored violet by ferric chloride.

Dioxy-alcoholic Acids, CgHj^Oj.

C,H,.C(0H)/^^^2-°^ C3H5.CH(0H).CH(0H).C0,H.

a-Phenyl Glyceric Acid. |3-Phenyl Glyceric Acid.

The a-Acid (Atroglyceric Acid) results on boiling dibrom-hydro-atropic acid
(p. 759) with excess of alkalies, and from benzoyl carbinol (p. 712) by means of
prussic acid and hydrochloric acid [^Berichte, 16, 1292). It crystallizes from water
in warty masses, and melts at 146°.

The /3-Acid (Phenylstyceric Acid) is obtained from (r;3-dibromhydrocin-
namic ester (p. 757) by first getting the dibenzoyl ester and saponifying it, or by
boiling phenyl-a-chlorlactic acid and the two phenyloxyacrylic acids (p. 777) with
water (together with phenylacetaldehyde) ; also by oxidizing cinnamic acid,
CjHj.CHiCH.COjH, with potassium permanganate (p. 460) {Berichte, 21, 920).
It is a crystalline mass, very soluble in water, and melts at 143°, with decomposi-
tion into phenylacetaldehyde, carbon dioxide and water, p- and o-Nitro-phenyl
glyceric acids have been obtained from nitrophenyl-glycidic acids (p. 777).

MONOBASIC TRIOXYACIDS.

Trioxybenzoic Acids, CjHeOs. Three of the six possible isome-
rides are known : —

I. Gallic Acid, C6H2(OH)3.C02H (i, 3, 4, 5— CO.,H in i),
occurs free in gall nuts, in tea, in the fruit of Casalpinia coriaria
(Divi-divi), in mangoes, and in various other plants. When com-
bined, and then chiefly as a glucoside, it occurs in some tannic

GALLIC ACID. 783

acids. It is obtained from the ordinary tannic acid (tannin) by
boiling it with dilute acids. It is prepared artificially on heating
di-iodo-salicylic acid to 130° with potassium carbonate, and from
brom-dioxy-benzoic acid, brom-proto-catechuic and veratric acids
(P- 779) when fused with potassium hydroxide.

Gallic acid arises, like pyrogallol carboxylic acid (below), from the adjacent
trioxybenzene (pyrogallol). Since the carboxyl in the latter occupies the ortho-
position referred to a hydroxyl, and since but 2 pyrogallol acids are possible, gallic
acid would then be the second isomeride (^Berichte, 17, 1090).

Gallic acid crystallizes in fine, silky needles, containing one
molecule of water. It dissolves in three parts of boiling, and 130
parts of water at 12°, and readily in alcohol and ether. It has a
faintly acid, astringent taste. It melts and decomposes near 220°,
into carbon dioxide, and pyrogallol, C6H3(OH)3. It reduces both
gold and silver salts (hence its application in photography). Ferric
chloride throws down a blackish-blue precipitate in its solutions.

Although gallic acid is monobasic, it can, by virtue of its being
a trivalent phenol, combine also to salts with four equivalents of
metal. The solutions of the alkali salts absorb oxygen when exposed
to the air, and, in consequence, become brown in color.

Gallic acid forms a triacetate, €5112(0. €21130)3. COjH, with acetyl chloride.
This crystallizes from alcohol in needles. The ethyl ester, CjH2(OH)3.C02.C2H5.
crystallizes with 2j^ molecules of H2O and is soluble in water. When anhydrous
it melts at 150°, and sublimes. Triethyl-gallaie, C3H2(0. €2115)3. CO2H, from
gallic acid, melts at 112°, and forms an easily soluble barium salt.

Rufigallic Acid, CijHjOg, a derivative of anthracene (see this) is obtained by
heating gallic acid with four parts of sulphuric acid to 140°.

Oxidizing agents, such as arsenic acid, silver oxide, iodine and water, convert
gaUic into EUagic Acid, Cj^HgOg. The latter occurs in the bezoar stones (an in-
testinal calculus of the Persian goat). It is obtained from this source by boiling
with potassium hydroxide, and precipitating with hydrochloric acid. Ellagic acid
separates out in the form of a powder containing I molecule of water of crystalliza-
tion. It is insoluble in water.

2. Pyrogallol-carboxylic i^cid, CjH2(OH)3C02H (i, 2, 3, 4 — COj in i), is
isomeric with gallic acid, and is prepared by heating pyrogallol with ammonium
carbonate. It dissolves with more difficulty in water, crystallizes in shining
needles containing i^HjO, and sublimes without decomposition in a current of
carbon dioxide. Ferric chloride colors it violet and greenish-brown ; it also re-
duces alkaline copper and silver solutions. Triethyl-pyrogallol-carboxylic Acid,
CjH2(O.C2H.)3.C02H, crystallizes in long shining needles, and melts at 105°. It
also results in the oxidation of triethyldaphnetic acid (vide this). It yields triethyl
pyrogallol by the elimination of carbon dioxide (p. 695).

3. Phloroglucin Carboxylic Acid, C5H2(OH)3.C02H (i, 2, 4, 6— COjH in
l), may be obtained by heating phloroglucin with potassium bicarbonate. It crys-
tallizes with one molecule of water, is very unstable and decomposes even at 100°,
also when boiled with water, into carbon dioxide and phloroglucin.

4. Oxy-hydroquinone Carboxylic Acid, CjH2(OH)3.C02H(i, 2, 4, COjH),
is not known in a free condition. Its triethyl-ether acid, €3112(0.02115)3.00211,
has been obtained from sesculetin. It melts at 134°, splits off carbon dioxide and
becomes triethyl-oxyhydroquinone (p. 696).

784 ORGANIC CHEMISTRY.

TANNIC ACIDS.

The tannins or tannic acids are substances widely disseminated
in the vegetable kingdom. They are soluble in water, possess an
acid, astringent taste, are colored dark blue or green (ink) by fer-
ric salts, precipitate gelatine and enter into combination (leather)
with animal hides (gelatine). Hence they are employed in the
manufacture of leather, and for the preparation of ink. They are
precipitated from their aqueous solutions by neutral acetate of
lead.

Some tannic acids appear to be glucosides of gallic acid, i. e.,
ethereal compounds of the same with various sugars. They decora-
pose into gallic acid and grape sugar upon boiling with dilute acids.
Others contain phloroglucin, C6H3(OH)3, instead of grape sugar.
Common tannic acid, tannin, appears to be, at least in a pure state,
not a glucoside but a digallic acid.

When the tannic acids are fused with potassium hydroxide they
yield mostly protocatechuic acid and phloroglucin.

Tannic Acid, Tannin, CuHioOj -f- 2H2O, Digallic Acid,
occurs in large quantity (upwards of 50 per cent.), in gall nuts
(pathological concretions upon the different oak species, Quercus
infectoria, .produced by the sting of insects) j in sumach {Hhus
coriaria), in tea and in other plants. It is prepared artificially by
oxidizing gallic acid with silver nitrate, by heating it with phos-
phorus oxychloride to 130°, or by boiling with dilute arsenic
acid. Conversely, it passes, on boiling with dilute acids or alka-
lies, into gallic acid (without the appearance of sugar) : —

Pure tannin must, therefore, be considered a digallic acid {Berichte,
17, 1478).

Tannin is best obtained from gall-nuts. The latter are finely divided and ex-
tracted with ether and alcohol. The solution separates into two layers, the lower
of which is aqueous and contains tannin chiefly, and this is obtained by evapora-
tion.

Pure tannic acid is a colorless, shining, amorphous mass, very
soluble in water, slightly in alcohol/ and almost insoluble in ether.
Many salts (1?. g., sodium' chloride) precipitate it from its aqueous
solutions, and it can also be removed from the latter with ether.
It reacts acid and is colored dark-blue by ferric chloride ; gelatine
precipitates it. Quantitative methods of estimating tannin are
based on this behavior.

The acid generally forms salts with two equivalents of metal ; these are obtained
pure with difficulty. Acetic anhydride converts the acid into a penta-acetate,

QUINIC ACID. 785

^1405(021130)509. Heated to 2lo° it decomposes with formation of pyrogallol,
C,H3(OH)3.

Gallyl-galhc Acid, Cj,H,„Og, a keto-tannic acid, forms an oxime and phenyl-
hydrazone, see Berickte, 22, Ref. 754; 23, Ref. 24.

The other tannic acids found in plants have been but little investigated : we
may mention: —

Kino tannin, which constitutes the chief ingredient of kino, the dried juice of
Pierocarpus erinaceus and Coccoloba uvifera. Its solution is colored green by
ferric salts. It yields phloroglucin on fusion with potassium hydroxide.

Catechu- Tannin occurs in catechin, the extract of Mimosa Catechu. Ferric
salts color it a dirty-green (p. 779). Catechin or Caterhinic Acid, Cj^HjjOg +
5H2O, is also present in catechu. It crystallizes in shining needles.

Moringa- Tannin, CjjHjjOg -\- HjO, Maclurin, is found in yellow wood
[Morus iinctoria) from which it may be extracted (along with morin) with hot
water. When the solution cools morin separates out; maclurin is precipitated
from the concentrated liquid by hydrochloric acid, in the form of « yellow crys-
talline powder, soluble in water and alcohol. Ferric salts impart a greenish-black
color to its solutions. When fused with caustic potash it yields protocatechuic
acid and phloroglucin.

Morin, CjjHjOg + ^HjO, decomposes into phloroglucin and resorcin. Nitric
acid oxidizes it to ;3-resorcylic acid.

The Tannin of Coffee, CjjHjgOjg, occurs in coffee beans and Paraguay tea.
Gelatine does not precipitate its solutions. Ferric chloride gives them a green
color. It decomposes into caffeic acid (see this) and sugar, when boiled with
potassium hydroxide. Protocatechuic acid is produced when it is fused with potas-
sium hydroxide.

The Tannin of Oak is found in the bark (together with gallic acid, ellagic acid,
quercite). It has the formula CjgHjgOid, and is a red powder, not very soluble in
cold water, but more readily in acetic ether. Ferric chloride colors its solution
dark blue. Boiling, dilute sulphuric acid converts it into the so-called oak-red
(phlobaphene), CjgHjgOj,.

The Tannin found in the quinine barks is combined with the quinia- alkaloids.
It closely resembles ordinary tannic acid, but is colored green by ferric salts.
When boiled with dilute acids it breaks up into sugar and quina-red, an amor-
phous brown substance, yielding protocatechuic acid and acetic acid on fusion with
potassium hydroxide.

Quinic Acid is very probably derived from hexahydrobenzene, C5Hg(H5)
(p. 567), and must be considered tetraoxyhexahydrobenzene carboxylic acid,
C,H(H5)(OH)^.C02H. It is apolyhydric phenol carboxylic acid. It is converted
into normal benzene derivatives in various reactions. Quercite is intimately
related to it (p. 697).

Quinic Acid, C7H12O6, is present in the cinchona barks, in
cofifee beans, in bilberry and many other plants. It is obtained as
a secondary product in the preparation of quinine, by extracting
the quinia bark with dilute sulphuric acid, and precipitating the
alkaloids with milk of lime. When the filtered solution is evapo-
rated the calcium salt of the acid separates out.

The acid consists of rhombic prisms, and dissolves very easily in water, but with
difficulty in strong alcohol. The aqueous solution is Isevo-rotatory. It melts at
66 ^^B

786 ORGANIC CHEMISTRY.

162°, and upon further heating decomposes into hydroquinone, pyrocatechin, ben-
zoic acid, phenol and other products. Oxidizing agents (MnOj and sulphuric acid)
convert it into formic acid, carbon dioxide and quinone. Ferments decompose it
into propionic acid, acetic acid and formic acid. It is a monobasic acid and
furnishes easily soluble salts. The calcium salt, {<Z^^-^-fi^)^Q.3. -\- loH^O,
crystallizes in rhombic leaflets, which effloresce on exposure to the air.
Quinic acid is reduced by hydriodic acid, to benzoic acid ; —

CeH,(0H)^.C03H + 2HI = CeH,.CO,H + 4H,0 + I^.

Phosphoric chloride converts it into chlor-benzoic chloride : —

CjH,(OI^)i.C02H + PCI5 = C5H4CI.COCI + PO^Hs + 3HCI + YLfi.

Acetic anhydride will convert its ethyl ester into tetracetyl-ethyl ester, CjH,(0.
€21130)4002.02115, which yields large crystals, melting at 135°-

DIBASIC ACIDS.

/CO w
Acids, CgHeOi = *~'8^*\.C0^H- There are three isomerides.

I. Phthalic Acid, CgHsO^ is the ortho-dicarboxylic acid of
benzene, and was first obtained by oxidizing naphthalene and
chlorinated naphthalenes with nitric acid. It also results on oxidizing
ortho-xylene and ortho-toluic acid with potassium permanganate,
alizarin and purpurin with nitric acid, or with manganese dioxide
and sulphuric acid ; and in slight amount in the oxidation of ben-
zene and benzoic acid. It is very difficult to get it by using chromic
acid as an oxidizing agent, since the latter is very apt to burn it at
once to carbon dioxide (p. 738). It can be synthetically obtained
from (7-nitrobenzoic acid by converting the latter into «;-cyan ben zoic
acid and then boiling this with alkalies (p. 752).

Preparation. — Boil naphthalene tetrachloride, CjoHgOl^, with 10 parts of
nitric acid (sp. gr. 1.45) until perfect solution is reached. Naphthalene tetra-
chloride is obtained by adding a mixture of naphthalene (2 parts) and potassium
chlorate (l part) to crude hydrochloric acid (11 parts) {Berichte, 11, 735).

Phthalic acid crystallizes in short prisms or in leaflets, which
dissolve readily in hot water, alcohol and ether. It melts above
200°, decomposes at 140° into phthalic anhydride (melting at 128°)
and water. When heated with an excess of calcium hydroxide it
yields benzene and 2CO2. Only iCOj is split off and calcium ben-
zoate produced (p. 741) if its lime salt be heated to 330-350° with
I molecule of Ca(0H)2. Barium chloride added to aqueous
ammonium phthalate precipitates barium phthalate, CsH^OiBa,
which is very sparingly soluble in water. . .js»-^ '

PHTHALIC ANHYDRIDE. 787

PCI5 converts phthalic acid, or phthalic anhydride at 170°, into phthalyl chlo-
ride, C|.H^(C0.C1)2. In accord with all its transpositions this appears to have

the constitution, CgH^^t^pQ 2 pO. Zinc and hydrochloric acid convert it into

phthalide (p. 772), diphthalyl, Zo(^^iyQ, : C^'^eHiXco, and /i)'droiii-
phthalyl (Berichte, 21, Ref. 139), and with benzene and AICI3, or with mercury
diphenyl it yields C5H4/^[^_«^^>0, phthalophenone, and with zinc ethyl,

Ethyl-phthalyl, C^Yi^(^^^2h>'^y "= produced. The latter does not com-
bine with hydroxylamine (^«-?V/5^i?,i7,8i7). Phenylhydrazine converts phthalyl chlo-
ride.or phthalic anhydride into phthalylphenylhydrazoncCgH /pl?^^^6^t> O,

melting at 178° {Berichie, 19, Ref. 303 ; 20, Ref. 255). With hydroxylamine,

C(N.OH)
phthalyl chloride yields the same phlhalyl-hydroxamic acid, C,H,(^ ^O,

^CO ^

melting at 230°, as is obtained from phthalic anhydride [Berichte, 16, 1781).
Phthalyl chloride is a liquid boiling at 268°, and reverts to phthalic acid when
boiled with water. The esters derived from phthalic chloride differ from those
derived from phthalic acid (Berichte, 16,860). Sodium amalgam converts phthalyl
chloride (unlike other transformations) into phthalyl alcohol (p. 712).

Phthalic Anhydride, CeHi^^pQ^O (see p. 402), is obtained

by distilling phthalic acid or digesting it with acetyl chloride. It
crystallizes in long, prismatic needles, melting at 128°, and boiling
at 284°. It yields phthalyl-hydroxamic acid with hydroxylamine,
and' phthalylphenyl-hydrazone with phenylhydrazine. Zinc dust
and glacial acetic acid convert it into phthalide (p. 772).

Phthalic anhydride readily condenses with unsaturated side-chains as a CO-
group is present to take part in the reaction (p. 716). Thus, phthalyl acetic acid
is formed on boiling the anhydride with acetic anhydride and sodium acetate, and.

C = CH — CH = C.
ethine diphthalyl, CgH^/ >0 0< )C5H^ {Berichte, 18, 3115),

when succinic anhydride and sodium acetate are used. It reacts in like manner
with malonic ester and aceto-acetic ester {Berichte, ig, Ref. 832). It condenses
with phthalide to diphthalyl (sefe this). Phthalic anhydride also condenses with
the benzenes forming benzoSbei'zoic acid and phenylphthalides. With the
phenols it yields the importanift'phthalein dyes (see these).

Phthalimide,C^U^(^yiiB. or CeH4^('^[^^^>0, is obtained:—

By heating phthalic anhydride or chloride in ammonia gas, or by heating

ammon^m phthalate;
By heating phthalic acid with ammonium or potassium sulphocyanide (p. 732)

{Berichte, 1%, 1398) ;
By the molecular rearrangement of the isomeric o-cyanbenzoic acid (p. 752)
{Berichte, ig, 2283).
Phthalimide cryst^Kes in six-sided prisms, which melt at 238°, and sublime.
It iotms potassium pmkalimide, C5H4(CO)2NK, by the action of alcohoUc potash.

788 ORGANIC CHEMISTRY.

Salts of the heavy metals can be obtained from it by double decomposition. The
metal in these salts can be replaced by various radicals {Berichte, 23, 994). Tin
and hydrochloric acid reduce phthalimide to —

Phthalimidine, C.H.^pU ^>0, which can also be made by a rearrange-
ment of o-cyanbenzyl alcohol, CgH^(CN).CH2.0H (Berichte, 22, Ref. 9; 23,
2479)-

Hydrophthalic Acids.

Phthalic acid can take up two, four and six hydrogen atoms, forming di- , tetra-,
and hexahydrophthalic acids. These must be considered as derivatives of hexa-
methylene, and the partially reduced benzene nuclei, CgHj,, and CjHg. A.
Baeyer's theory (Annalen, 258, 145; Berichte, 23, Ref. 577), based on the spatial
configurations of van't Hoff as to the union of the C-atoms, is best explained by the
scheme of KekulS, and allows for seven dihydrophthalic acids (enantiomorphous
forms not included) : one geometrical and six structural isomerides. But one of
the seven forms is known. It also supposes the existence of six tetrahydrophthalic
acids (four structural isomerides and two geometrical isomerides — the four first
are known), and two geometrically isomeric hexahydrophthalic acids. The latter
isomerism is due to the different positions occupied by the carboxyls relatively to
the plane of the hexamethylene ring, and corresponds to that of maletc and fumaric
acid (Annalen, 258, 176) ; hence the isomerides are termed maleinoid dind/uma-
roid (or cis and trans) forms. Baeyer indicates the structure of the di- and tetra-
hydro-acids by representing the double unions with A (see p. $68). The partially
hydrided phthalic acids behave the same as the unsaturated acids of the paraffin
series. They unite quite readily with bromine and are oxidized with ease by potas-
sium permanganate.

Dihydrophthalic Acid, Q^^{^^{Q,0,j^S^^ (l, 2), results from the action of
sodium amalgam upon a cold solution of phthalic acid. The acid melts at 215°,
combines readily with Brj and two molecules of hydrobromic acid, and is.at once
decomposed by potassium permanganate [Berichfi, 23, Ref. 578).

Tetrahydrophthalic Acids, Q, ^ ^{fi ^{0,0 fi^ ^. Four of the six possible iso-
merides are known.

The A J -acid is produced by the solution of its anhydride in hot water. It crys-
tallizes in leaflets containing one molecule of water. They effloresce quite rapidly.
The acid is very similar to pyrocinchonic acid (dimethyl maleic acid, p. 430), and
readily changes to its anhydride, CgHgOj. The latter can also be obtained
by the distillation of hydropyromellitic acid. It crystallizes from ether in leaflets.
It melts at 74°, and is readily volatilized. Boiling potash converts the Aj-acid into
the Aj-acid {Berichte, 23, Ref. 579; Annalen, 258, 161).

Aj- and A^-Tetrahydrophthalic Acids are formed by reducing phthalic acid with
sodium amalgam or by boiling dihydrophthalic acid. The first melts at 215-218°,
and yields an anhydride, melting at 140°. The second acid yields the Aj-acid
when heated to 220° or if boiled with water. The-Aj-acid melts at 174°.

Hexahydrophthalic Acid, C5Hj(,(C02H)2,existsin a fumaroid axid. maleinoid
form. The first dissolves with difficulty and melts at 215°. It forms an anhydride
with acetyl chloride, melting at 140°. The maleinoid form is more soluble in
water and melts at 192°, forming an anhydride, melting at 32°. (For its analogy
with fumaric and maleic acids, see Annalen, 258, 176.)

2. Isophthalic Acid, QHi^^q'^jj (1,3), is obtained: by

oxidizing isoxylene and isotoluic acid with a chromic acid mixture ;
by fusing potassium »2-sulphobenzoate, »2-bromb6nzoate and ben-

TEREPHTHALIC ACID. 789

zoate with potassium formate (terephthalic acid is also formed in
the last two cases) ; by the action of the ester of chlorcarbonic acid
and sodium amalgam upon w-dibrombenzene ; from w-dicyanben-
zene (p. 735) and ;;z-cyanbenzoic acid (p. 752); also by heating
hydro-pyromellitic and hydro-prehnitic acid (p. 798), and by oxi-
dizing colophony with nitric acid. Isophthalic acid crystallizes
from hot water in fine, long needles. The most convenient method
for its production consists in converting m-xyly\ene bromide into
the diethyl ether and then oxidizing the latter {Berichte, o.x, 47).
It is soluble in 460 parts boiling, and 7800 parts cold water. It
melts above 300°, and sublimes in needles.

The harium salt, CgH^OiBa + 3H2O, crystallizes in fine needles, and is
very soluble in water; therefore, it is not precipitated by barium chloride from a
solution of ammonium isophthalate (distinction between phthalic and terephthalic
acids).

The Dimethyl-isophthalati, C^^iCO^.CB.^^, crystallizes from alcohol in
needles, and melts at 65°. The diethyl ester is liquid, solidifies below 0°, and boils
at 285°.

Isophthalyl Chloride, CjH^02Cl2, is formed upon heating isophthalic acid
with PCI5 to 200°. Its formula is Z^\i^(COZ\)^. It melts at 41° and boils at
276°- There is only one tetrahydro-acid derived from the hydroisophthalic acids.

3. Terephthalic Acid, C6H4(C02H)2 (i, 4), was first obtained
by oxidizing turpentine oil. It results in oxidizing paraxylene,
paratoluic acid and all di-derivatives of benzene having two carbon
chains belonging to the para-series {e. g., cymene and cumene)
with chromic acid. The oxidation of crude xylene affords tere-
phthalic (15 per cent.) and isophthalic (85 per cent.) acids, which
are separated by means of their barium salts. Terephthalic acid is
produced, too, when /-dicyanbenzene, C6H4(CN)2 (p. 735), and
/-cyanbenzoic acid are boiled with alkalies as well as from
/-dibrombenzene, by the action of chlorcarbonic acid and sodium.
The best course to pursue in forming terephthalic acid is to oxidize
caraway oil (a mixture of cymene and cuminol) with chromic acid,
or it may be prepared from />-toluidine by changing this into the
nitrile, C6H4(CH3).CN, etc. {Berichte, 22, 2178).

Terephthalic acid is a powder, which is almost perfectly insoluble
in water, alcohol and ether, and is, therefore, precipitated from its
salts by acids. It sublimes without previous fusion when it is
heated. Sometimes terephthalic acid is obtained with properties
slightly different from the regular acid (insolic acid). The cause
of this seems to be due to an admixture of acetophenone-carboxylic
acid.

The calcium salt, CgH^OjCa -f 3H2O, and barium salt, CgHjOjBa -f 4HjO,
are very sparingly soluble in water. The methyl ester, C8H^(CH3)20^, melts at
140° ; the ethyl ester, at 44°.

Terephthalyl Chloride, CgH^(C0Cl)3, is formed when terephthalic acid is

790 ORGANIC CHEMISTRY.

heated with PCI5. It melts at 78° and boils at 259°. It forms terephthalophe-
none with benzene and AICI3.

Nitrolerepkihalic Acid is produced when terephthalic acid is boiled with con-
centrated nitric acid. It melts at 259° Reduction converts it into amidotere-
phthalic acid, C5H,(NH2).(C02H)2, which can be further changed to cyantere-
phthalic Acid, CgH3(CN) (COjH)^ {Berichte, ig, 1634).

Hydroterephthalic Acids.

Ten hydroterephthalic acids are possible according to Baeyer's theory : five
dihydro-, three tetra-hydro, and two hexahydro acids ; three of these are geomet-
rical isomerides {^Annalen, 259, I and 149 ; Berichte, 23, Ref. 569, 577)- The
unsaturated hydrophthalic acids contain only double (no para) linkages. In de-
portment they are perfectly analogous to the unsaturated acids of the paraffin
series, particularly muconic acid and the two hydro-muconic acids [Berichte, 23,
Ref. 231). Ferricyanide of potassium oxidizes most of the hydro-acids to
terephthalic acid. They are completely destroyed by potassium permanganate.
With bromine the Aj, 3- and Aj, j-dihydro-acids yield only dibromides, whereas
the acids Aj, ^- and Aj, 5- yield tetrabromides. The first product in the oxidation
of terephthalic acid is Aj, g-dihydro-terephthalic acid. A para addition very prob-
ably occurs in this instance, which finds explanation, according to Baeyer, in the
analogous deportment of muconic acid [Annalen, 208, 148; 256, l).

The ten isomerides have all been prepared and differ in their constitution
(Baeyer, Berichte, 23, Ref. 570).

2. Acids, CgHgO^. (i) Methylphthalic Acids, CsH3(CH3) | qq^^.

Uvitic Acid, Mesidic Acid (i, 3, 5), is obtained by oxidizing mesitylene,
CsH3(CH3)3, with dilute nitric acid (mesitylenic acid is produced at the same
time, p. 756). It is formed synthetically by boiling pyroracemic acid with baryta
water (p. 566). It crystallizes from hot water in needles, melting at 287°.
Chromic acid oxidizes it to trimesic acid (p. 797) ; distilled with lime it at first
yields metatoluic acid, then toluene (p. 741).

The synthesis of uvitic acid from pyroracemic acid is due to the condensation
of three molecules of pyroracemic acid, with one molecule of acetaldehyde. In
this reaction a portion of the pyroracemic acid is decomposed. If a mixture of
pyroracemic acid and higher fatty aldehydes be used homologous alkylisophthalic
acids, C3H3(R)(C02H)2, will result. Thus propyl aldehyde produces ethyliso-
phthalic acid, C5H3(C2H5)(COjH)j, isobutyric aldehyde yields isopropyl isophthalic
acid, etc. (Doebner, Berichte, 23, 2377).

Xylidic Acid,C8H3(CHj).(C02H)2, is obtained by oxidizing pseudocumene,
^6H3('--H3)3 (i, 3, 4), xylic acid and so-called paraxylic acid with dilute nitric
acid; hence its structure is (l, 3, 4 — CH3 in 3) (p. 756). Potassium permanga-
nate oxidizes it to triraellitic acid. It separates from boiling water in flocculent
masses ; melts at 282° and sublimes.

(2) Homophthalic Acids, C ^Yi. ^(^^^•^^ .

Phenylaceto-carboxylic Acid, Isouvitic Acid, is the ortho-compound. It
may be obtained by fusing gamboge with caustic potash (Berichte, 19, 1654),
and by saponifying cyan-o-toluic acid (from phthalide and potassium cyanide,
p. 772)- It crystallizes from hot water in stout prisms, melting at i7S°i with the

PHENYL-SUCCINIC ACID. 79 1

elimination of water. Its anhydride, CgHgOj, obtained by digesting the acid
with acetyl chloride, melts at 141°.

Homophthalimide, CjH,N02, is produced when the aniimonium salt is
heated. It crystallizes in minute needles, melting at 233° and distilling without
decomposition. When it is heated with phosphorus oxychloride it yields dichlor-
isoquinoline, CgH5NCl2, which becomes isoquinoline when further heated with
hydriodic acid {Berichte, 19, 2354) ; —

.CH^.CO .CH:CC1 .CH:CH

C,H / I C^H / I CeH / | .

^CO. NH \CC1:N ^CH:N

Homophthalimide. Dichlorisoquinoline. Isoquinoline.

Homophthalimide is directly converted into isoquinoline when it is heated with
zinc dust; the reaction is analogous to the production of pyrrol from succinimide
{Berickle, 21, 2299).

The hydrogen atoms of the CH^-groups are replaced by two alkyls when
homophthalimide is heated with caustic potash and alkyl iodides. Mono-aWyl
derivatives of homophthalimide are also produced when ^-cyanbenzyl cyanide,

CgH^^P^^- (homophthalonitrile), is alkylized and further re-arranged

(Berichte, 20, 2499). 1

The /ara-compound, homoterepkthalic acid, CjH^(C02H).CH2.C02H, has
been obtained from /-cyanbenzyl cyanide, C5H^.(CN).CH2.CN, and melts at
228° {Berichte, 22, 3216).

(3) Phenyl Malonic Acid, C|,H5.CH(C02H)2. Ta^ ethyl ester of dinitro-
fhenylmalonic acid may be obtained ifrom sodium malonic ester and bromdinitro-
benzene. It forms yellow prisms, melting at 51°. It dissolves in the alkalies
forming dark-red colored salts {Berichte, 21, 2740). Dinitrobromphenylmalonic
ester {Berichte, 21, 2034) is formed by the action of tribromdinitrobenzene upon
malonic ester.

(3) Acids, C,„Hi„0,-

Dimethyl Phthalic Acids, CsH2(CH3)2(C02H)2. Two isomeric acids,
called cumidic acids, have been obtained by the oxidation of durene and durylic
acids (p. 760) {Berichte, ig, 2508).

o-Hydrocinnamic Carboxylic Acid, C^^'Cr'^''''^ 2- 2 ^j^ 2), is

formed by oxidizing tetrahydro-;3-naphthylamine with potassium permanganate.
It melts at 165° {Berichte, 23, 1562; 21, II20).

Phenylene Diacetic Acids, ^i^iCrY^rc^vi- T^T^e para- and ortho-
acids have been obtained from the xylylene cyanides (p. 735). The first melts at
244°, and the second at 150°.

CjH5.CH.CO2H

Phenyl-Succinic Acid, | , results from a-chlorstyrene,

CHj.COjH
CgH5.C2H3Cl, by means of potassium cyanide; by the decomposition of phenyl-
acetsuccinic ester, by means of alkalies ; from phenyl-ethane-tri-carboxy-succinic
acid (p. 797), and from the so-called hydro- cornicularic acid, CjjHigOj. It crys-
tallizes from hot water in warty masses, melts at 167° (162°) and (like succinic
acid) yields an anhydride, CjjHgOg, melting at 54°.

Phenylmalic and phenylmaleic acids {Berichte, 23, Ref. 573) are produced
when bromine, etc., acts upon phenylsuccinic acid.

;3-Phenylisosuccinic Acid, CgH5.CH2.CH(C02H)2, Benzyl Maloaic Acid,

792 ORGANIC CHEMISTRY.

formed from sodium malonic ester, CH(Na)(COjR)j, and benzyl chloride is very
readily soluble in water, melts at 117°, and at 180° decomposes into carbon diox-
ide and hydrocinnamic acid, CgHj.CHj.CHj.COjH.

The ester of dibenzyl malonic acid, (CgH5.CH2)2C.(C02H)2 {Berichte, 20,
Ref. 380), is produced simultaneously with benzyl malonic ester by the entrance of
a second benzyl group.

The action of 0- and /-nitrobenzyl chloride upon malonic ester produces the
corresponding nitrobenzyl- and bi-nitrobenzyl-malonic esters [Berichte, 20, 434).

4. Benzylsuccinic Acid, C5Hg.CH2.C2H3(C02H)2 = CnHjjO^, results
from ethan-tricarboxylic ester (p. 471), or elhan-tetracarboxylic ester (p. 481), by
the action of benzyl chloride, etc. [Berichte, 17, 449), as well as by the reduction
of phenylitaconic acid [Berichte, 23, Ref. 237). It melts at 161° and forms an
anhydride, melting at 102°.

Symmetrical benzyl-alkyl-succinic acids, capable of existing in two alloisomeric
forms, are similarly produced [Berichte, 23, 1942).

OXYDICARBOXYLIC ACIDS AND OXYALDEHYDIC ACIDS.

The oxyphthalic acids, CgH^Oj = CjH3(OH).(C02H)2,can be obtained from
the phthalic acids by the introduction of the OH-group by means of the amido-
or sulpho-derivatives. They are also formed from the oxy-monocarboxylic acids,
C5H4(OH).C02H, by heating their alkali salts in a current of carbon dioxide, or
by means of the CCl^ reaction (p. 767). Their ether acids, e.g., C5H3(O.CH3)
(C02H)2, result by the oxidation of the ether acids of the oxytoluic acids, C5H3

(O.CH3) s^fn H (P' 77')' ^""^ ^y ''^^ same treatment of the oxyaldehydic acids,
CgH3(O.CH3)^ pp. „ (the latter are obtained from the oxymonocarboxylic

acids, C5H^(OH).C02H, by means of the CCI3H reaction, and by further intro-
duction of methyl) ; when the phenol ethers are heated with hydrochloric acid the
free oxydicarboxylic acids result. Hence, the six possible Oxyphthalic Acids,
CgH3(OH).{C02H)2, can be obtained by these reactions [Berichte, 16, 1966).

Oxyterephthalic Acid, CgH3(OH)(C02H)2, has been obtained from niiro-
terephthalic acid. It is a powder that dissolves with great difficulty. Sodium
amalgam C9nvertsitinto Tetrahydro-oxyterephthalic Acid, CgH,(0H)(C02H)j,
or CgHj(0)(C02H)2, which at 118° (or readily when heated with water) decom-
poses into carbon dioxide and Hexahydro-ketobenzoic Acid, COjH.C

H^ p,„*'p„2>CH2. The latter is a syrup. It forms an oxime with hydroxyla-

mine and a hydrazone with phenylhydrazine. Acids transform the latter into a
carbazol derivative [Berichte, 22, 2179).

C3H5.C(OH).C02H C5H5.CH.CO2H

Phenyl-malic Acids, | and | . The

CH2.CO2H CH(0H).C02H

first may be obtained from phenylsuccinic acid by the action of bromine and
water. It melts at 187°. The second acid is derived from phenyl-formyl acetic
ester (p. 761) by the action of CNH, etc. It melts at 150-160° [Berichte, 23,
Ref. 572)- r OH

Oxyuvitic Acid, CgHjOj = C3H2(CH3) X irc\c\V\ > '^ ^ homologue of the

oxybenzenedicarboxylic acids, and is produced by the action of chloroform, chloral
or trichloracetic ester upon sodium aceto-acetic ester [Annalen, 222, 258). It
crystallizes from hot water in fine needles, and melts with decomposition at
about 290°.

DIOXY-CARBOXYLIC ACIDS. 793

The 7-oxybenzene dicarboxylic acids at once eliminate water and become lac-
tonic acids. In this class may be included : — /CHCO^H

Phthalid-carboxylic Acid, C9H5O4 = CgH^ \„ . This is produced

\co/"-'

by reducing phenyl-glyoxyl-o-carboxylic acid (p. 765) with sodium amalgam (Be-
richte, 18, 381). It is quite soluble in water, crystallizes in leaflets, melts at 149°,
and beyond l8o° decomposes into carbon dioxide and phthalide.

/CH-CHj-COjH

Phthalid-acetic Acid, CioHjO^ = C5H^ \„ . Derived from

\C0/^
benzoyl aceto-carboxylic acid (p. 765) by the action of sodium amalgam. It is
very soluble in hot water and alcohol. It crystallizes with one molecule of water
in delicate needles, melting at 151°.

Phenyl-paraconic Acid, CuHijO^, and Phenyl-itamalic Acid,
C11H12O5:—

C,H,.CH.CH(CO,H).CH,

i cL c,h,.ch(oh).ch/co,h^^^

Phenyl-paraconic Acid. Phenyl-itamalic Acid.

The lactone acid of phenyl-itamalic acid is obtained by heating benzaldehyde
with sodium succinate and acetic anhydride. It crystallizes from hot water in
shining needles, and melts at 99°; when perfectly anhydrous at 109°. When
it is boiled with alkalies it yields the salts of phenyl-itamalic acid. The latter,
when in a free condition, immediately reverts to phenyl-paraconic acid. This,
upon distillation, breaks down into carbon dioxide, phenylbutyrolactone (p. 777)
and phenylisocrotonic acid. A further product is a-naphthol.

Three chlorparaconic acids are similarly produced from sodium succinate and the
three chlorbenzaldehydes. They yield three chlorinated a-naphthols (Berichte, 21,
Ref. 733). Pyrotartaric acid and benzaldehyde (p. 462) yield a- and ^-methyl-
phenyl paraconic acid, CjjHjjOj, from which melhyl-a-naphthol may be produced
by distillation {^Berichte, 23, Ref. 96). Sodium, or sodium ethylate, acting upon
phenyl-paraconic ester, produces /A^»j)/^-//(j:i-»K«Va«V,CgH5.CH:CH(C02H)CH2.
COjH \Berichie, 23, Ref. 236), by a reaction peculiar to lactonic acids.

DIOXY-CARBOXYLIC ACIDS.

Dioxyphthalic Acids, CgH2(OH)2(C02H)2. Eleven isomerides.

I. There are four possible dioxy-acids of ortho-phthalic acid. The most re-
markable of these is dioxy-phthalic acid (i, 2, 4, 5 — the hydroxyls in 4 and 5). It '
has not yet been isolated, because it readily loses carbon dioxide and passes into
protocatechuic acid (2, 4, 5 — CO2H in 2). The following compounds are among
its derivatives ; they have been prepared from narcotiu : hemipinic acid, CjuHjjOg,
opianic acid, Cj^Hj^Oj, noropianic acid, C3H5O5, meconinic acid, CiuHj^Oj, and
meconine, CiqHjdO^ : —

r(O.CH3)2(4,5) fCHO fCO.CH^)^

c.hJco^h (2) c.hJco^h c.hJco^h

(COjH (I) ((0H)2 ICHO

Hemipinic Acid. Noropianic Acid. Opianic Acid.

c.hJco \q

ICH2/"

Meconine.

794 ORGANIC CHEMISTRY.

Hemipinic Acid, CijHjjOg. This should be regarded as a carboxyl derivative
of dimethyl protocatechuic acid, since it decomposes, when heated with hydro-
chloric acid, into protocatechuic acid, carbon dioxide and methyl chloride : —

CioHioOe + 2HCI = CjHeO^ + CO^ + 2CH3CI.

It is formed together with opianic acid and meconine by oxidizing narcotin with
dilute nitric acid. In an anhydrous state it melts at 182°, and yields an anhydride,
melting at 167°. Hence, the CO2H groups occupy the ortho-position.

Metahemipinic Acid, isomeric with hemipinic acid, is formed by the oxida-
tion of papaverine {Berichie, 21, Ref. 787 ; 22, Ref. 195).

Noropianic Acid, CjHgOj, dioxyaldehyde carboxylic acid, aldehydo-proto-
catechuic acid (see above), is obtained from opianic acid by the elimination of the
two methyl groups upon heating with hydriodic acid (isovanillin is simultaneously
formed by the removal of one methyl group and carbon dioxide). It is rather
readily soluble in water, melts when anhydrous at 171°, and is colored bluish-green
by ferric chloride.

Opianic Acid, CjoHj^Oj, the dimethyl ether of the preceding compound, is
an aldehyde-dimethyl-protocatechuic acid, because when it is heated with hydro-
chloric acid it yields protocatechuic aldehyde, carbon dioxide and two molecules
of methyl chloride. It is converted into dimethyl-protocatechuic aldehyde
when heated with soda-lime. It crystallizes from hot water in fine prisms,
melting at 150?. It is oxidized to hemipinic acid. Opianic acid unites with
phenylhydrazine with the elimination of two molecules of water {Berichte, 19,
763). Consult .5^r;V/^/^, 21, 2518, for its combinations with diphenylhydrazine,
hydrazobenzene, etc. When opianic acid combines with hydroxylamine, two
molecules of water escape, and hemipinimide {Berichte, ig, 2278, 2913) is formed.
Consult Berichte, ig, 2299 ; 20, 875 for azo-opianic acid derived from nitro-opianic
acid.

Meconine, Cj5Hjd04, results when sodium amalgam acts upon opianic acid and
the solution is precipitated by acids. At first the sodium salt of Meconinic Acid,
C,5Hj.^05, is produced. The latter is a 7-oxyacid, and at once parts with water,
passing into its lactone anhydride — meconine (see Phthalide, p. 772). Meconine
occurs already formed in opium, and is obtained on boiling narcotine with water.
It yields shining crystals, melting at 102°, and dissolving with difficulty in water.
It dissolves in the alkalies, yielding salts of meconinic acid. In the same manner
that phthalimide yields phthalide (p. 788), hemipinimide furnishes ■^-meconine,
and not meconine {^Berichte, 20, 883).

2. The most interesting of the four possible dioxy-acids derived from tere-
phthalic acid is —

/-Dioxy-terephthalic Acid, CgH2(OH)2(C02H)2 (i, 4-2, 5), containing
the hydroxyl groups in opposite para-positions. It is isomeric or tautomeric with
hypothetical diketo-tetrahydro-benzene dicarboyxlic acid : —

^^°2<^\CH = C(0H)/^''^°2^ HCO,.C^(, jj ^ _ (^Q^C.COjH.

/-Dioxyterephthalic Acid. Diketo-tetrahydro-benzene'

Dicarboxylic Acid.

Free dioxyterephthalic acid may be obtained by boiling its ester with sodium
hydroxide. It crystallizes from alcohol in yellow leaflets, containing two mole-
cules of water. Ferric chloride imparts a deep blue coloration to its solution.
When rapidly distilled it decomposes into two molecules of carbon dioxide and
hydroquinone. Sodium amalgam reduces it to succino-succinic acid {Berichte, 22,
2l68). Its diethyl ester, C^f)^^^)^, may be prepared by withdrawing two
hydrogen atoms from succino-succinic ester (C8Hg08(CjH5)2), by means of bro-

DIOXY-CARBOXYLIC ACIDS. 79S

mine or PCI5 [Berichte, 22, 2107), or by the action of sodium ethylate upon di-
bromacetoacetic ester (Annalen 219, 78). It crystallizes in two distinct forms,
at the ordinary temperature in yellowish green prisms or plates, at higher tempera-
tures in colorless leaflets. It also sublimes in the latter form. It melts at 133°.
In most of its reactions the ester conducts itself like a hydroxyl-derivative. It
does not combine with hydroxylamine or phenylhydrazine, and with sodium and
allcyl iodides yields dialkyl esters. It, however, does not react with phenylcyanale
(P- 613) {^Berichte, 23, 259), and shows some analogies with succino-succinic
ester. Hence, it is considered a quinone- or diketo- derivative — corrresponding to
the tautomeric formula given above. The different physical modifications of the
ester and analogous compounds, according to Hantzsch, correspond to the two
desmotropic conditions (p. 54) — the colored variety agreeing with the quinone
formula, while the colorless corresponds to the hydroxyl formula [Berichte, 22,
1294). However, the color cannot be regarded as a certain criterion for the dis-
tinction of the ketone from the hydroxyl form. Even chemical reactions do not
prove that desmotropic forms can be accepted (Nef, Berichte, 23, Ref. 585 ;
Goldschmidt, Berichte, 23, Ref. 260).

Dioxyterephthalic ester, by reduction (boiling with zinc and hydrochloric acid
in alcoholic solution), Is again changed to succino-succinic ester [Berichte, ig,
432; 22, 2169). A dihydroxamic acid is formed with hydroxylamine hydro-
chloride; tetrahydrodioxy-terephthalic acid, CgH2(HJ(OH)2(C02H)2, is pro-
duced at the same time, and decomposes at 180° with carbonization [Berichte,
22, 1280).

Succino-succinic Acid, CgHgOg, may be represented by either of the follow-
ing formulas : —

HCOj.CH.CO.CH2 HCOj.C = C(OH) — CHj

II or I I •

CHj.CO.CH.COjH CH,— C(OH) = C.CO.,H

/-Diketo-hexahydro-benzene Dioxy-dihydro-terephthalic Acid.

Dicarboxylic Acid.

The first is derived from hexahydrobenzene, the second from Aj.^-dihydrotere-
phthalic acid [Berichte, 22, 2107 and 2169). The diethyl ester is produced by
the condensation of two molecules of succinic ester through the agency of sodium
or sodium ethylate upon succinic ester or bromacetoacetic ester (p. 333) [Berichte,
21, 1464; 22, 1282). It crystallizes in bright green triclinic prisms or colorless
needles, melting at 126-127°. It is insoluble in water, dissolves with difficulty in
ether, very readily in alcohol ; its solution shows a bright blue fluorescence.
Ferric chloride imparts a cheny red color to it. The dimethyl ester, CgHgOg
(CH3)2, from methyl succinic ester, melts at 152°. The esters dissolve in alkalies
(not ammonia) with a yellow color. They yield metallic derivatives by the
replacement of two hydrogen atoms [Berichte, 19, 428).

With hydroxylamine (in alkaline or acid solution) succino-succinic ester does
not react directly like a diketone, but, splitting off CO^R and four hydrogen
atoms, yields quinone-dioxime carboxylic ester (GgH3(N.OH)2.C02R), forming
yellow needles, melting at 174° [Berichte, 22, 1283). The ester appears to form
a normal hydrazone with phenylhydrazine [Berichte, 19, 429). It does not react
with phenylcyanate [Berichte, 23, 258). PCI5 converts the ester into dichlor-
hydroterephthalic acid, C ^Yi ^C\ ^(CO ^B.) ^ [Berichte, 21, 468).

If succino-succinic ester be saponified by dilute alkalies, with exclusion of air,
it yields free

Succino-succinic Acid, CgHgO,, = C^Vi.fi^[Q.O^Yi)^ (see above). This may
be more readily obtained by boiling dioxyterephthalic ester with sodium hydroxide
and reducing the product with sodium amalgam [Berichte, 22, 2168). It is a

7g6 ORGANIC CHEMISTRY.

yellow pulverulent precipitate, which dissolves with difficulty. Air oxidizes it in
solution to dioxyterephthalic acid. Water gradually decomposes it into carbon
dioxide and succinylo-propionic add, CgHg02.C02H. The acid breaks down
into two molecules of carbon dioxide and diketohexamethylene upon the applica-
tion of heat.

Chlorine converts succino-succinic ester and dioxyterephthalic ester into /-di-
chlorquinone-dicarboxylic ester, CCl202(C02.C2H5)2. This consists of greenish
yellow crystals, melting at 195°. Bromine produces the analogous dibrom-
derivative [Serichte, 21, 1761). Zinc dust and glacial acetic acid yield

Dichlorhydroquinone-dicarboxylic Ester, CeCl2H202(C02R)2, crystal-
lizing in two different forms — colorless needles and yellow-green plates, corre-
sponding to the desmotropic forms (see above) (Berichte, 20, 2796) : —

R.CO2.C — CCl = C(OH) R.CO2.CH — CCl — CO

II I and I I

C(OH) — CCI = C.C02R CO — CCl = CH.CO2R.

However, the existence of a chemical difference has not been proven (^Berichte,
23, 260). Dibromhydroquinone-dicarboxylic Ester, C5Br2H202(C02R)2
{Berichte, 21, 17S9), shows a like deportment.

Dioxy-quinone-dicarboxylic Ester, C8H2(OH)2(C02R)2 = CgH20gR2,
may be prepared by shaking dichlorhydroquinone-dicarboxylic ester wiih sodium
hydroxide, and by the action of nitrous acid upon dioxy-terephthalic ester [Berichte,
19, 2385). It melts at 151°, and crystallizes in pale yellow leaflets and intense
greenish yellow prisms. The latter form is probably diquinoyl-dihydrobenzene
dicarboxylic ester, CjH2(02)(02)(C02R)2 {Berichte, 20, 1307). It reacts acid,
and forms salts with two equivalents of the metals. It does not form a dioxime
with hydroxylamine, but an oxyammonium salt, and with phenylhydrazine a
phenylhydrazine salt {Berichte, 22, 1290). Furthermore, it does not react with
phenylcyanate {Berichte, 23, 265). Boiling hydrochloric acid decomposes the
ester into carbon dioxide and dioxy-quinone (p. 702). By the absorption of two
atoms of hydrogen (by reduction with sulphurous acid) the ester becomes

Tetroxy-terephthalic Ester, Cg(0H)j(C02R2), or Dioxy-quinone-dihydro-
carboxylic Ester, C5H2(02)(0HJ2(C02R)2- It crystallizes in golden yellow
leaflets and melts at 178° {Berichte, 20, 2798). Its alkaline solution oxidizes on
exposure to the air (giving up two hydrogen atoms) to dioxy-quinone-dicarboxylic
ester, hence, it yields the same products with hydroxylamine and phenylhydrazine
{Berichte, 22, 1291). It forms a tetracarbanilido-derivative {Berichte, 23, 267)
with four molecules of phenylcyanate.

The following is a trioxy-dicarboxylic acid : —

Gallocarboxylic Acid, C6H(OH)3(C02H)2 = CgHgO,. It maybe prepared
from pyrogallol by heating it to 180° with ammonium carbonate. Pyrogallo-car-
boxylic acid is formed at the same time. It dissolves in water with difficulty,
crystallizes in needles, and melts at 270° with decomposition.

TRIOXY-TRICARBOXYLIC ACIDS. 797

TRIBASIC ACIDS.
Benzene Tricarboxylic Acids, C6H3(C02H)3, 3 isomerides.

1. Trimesic Acid, CgHeOa (i, 3, 5), is formed when mesity-
lenic and uvitic acids are oxidized with a chromic acid mixture
(mesitylene is at once burnt up) ; by heating melUtic acid with
glycerol (together with tetracarboxylic acids), or hydro- and iso-
hydromellitic acid with sulphuric acid. The synthetic methods for
its production are : heating benzene trisulphonic acid with potassium
cyanide and saponifying the resulting cyanide (p. 660) ; by poly-
merizing propiolic acid (p. 565) ; and by the action of sodium upon
a mixture of acetic and formic esters (p. 566). It crystallizes in
short prisms, which dissolve readily in hot water and alcohol. It
melts about 300°, and sublimes near 240°. Heated with lime it
decomposes into 3CO2 and benzene. Its triethyl ester melts at
132°.

2. Trimellitic Acid, CjH3(C02H)3 (l, 2, 4). This is obtained (together
with isophthalic acid) by heating hydropyro-mellitic acid with sulphuric acid, or
upon oxidizing, xylidic acid with potassium permanganate. It is prepared most
readily (along with isophthalic acid) by oxidizing colophony with nitric acid
[Annalen, 172, 97), is very soluble in water, and separates in warty masses. It
melts at 216°, decomposing into water and the anhydride, C5H2(C02H)(CO)20.
The latter melts at 158°.

3. Hemimellitic Acid, CgH3(C02H)3 (i, 2, 3). This is formed on heating
hydromellophanic acid (below) with sulphuric acid. It forms needles, which are
sparingly soluble in water, melts at 185°, and decomposes into phthalic anhydride
and benzoic acid.

Phenyl-ethenyl-tricarboxylic Acid, CsH5.CH(C02H).CH(C02H)2 (vide
p. 471), is obtained from phenylchloracetic ester, CjH5.CHCl.CO2R, by the action
of sodium malonic ester, CHNa(C02R)2. It is a crystalline mass, easily soluble
in water, and at 191° decomposes into carbon dioxide and phenyl succinic acid
(p. 791) {BeHchte, 23, Ref. 573).

TRIOXY-TRICARBOXYLIC ACIDS.

Phloroglucin-tricarboxylic Acid, CgHgOg = C5(OH)3(C02H)3 or C5H3
O3 (C02H)3 (p. 695), belongs to this class. Its triethyl ester may be formed by the
condensation of malonic ester upon heating its sodium compound to 120-145°
(p. 566), or by the action of zinc alkyl. The ester, C9H3(C2H5)309, crystallizes
from alcohol in yellow needles. These melt at 104°. It dissolves in ether with
a greenish fluorescence. It deports itself quite like succino-succinic ester, dissolves
unchanged in alkalies, and is colored a cherry-red by ferric chloride. Acetic
anhydride converts it into a triacetyl derivative, and with hydroxy lamina it yields
a trioxime, CgH3(N.OH)3(C02R)3 [Berichte, 21, 1766), with phenyl cyanate it
forms a tricarbamido-derivative \Berichte, 23, 270). Fused with alkalies it forms
phioroglucin.

798 ORGANIC CHEMISTRY.

TETRABASIC ACIDS.
Benzene Tetracarboxylic Acids, CgH2(C02H)^. There are three isomerides.

1. Pyromellitic Acid, CuHjOj (i, 2, 4, 5). Its anhydride is produced
when mellitic acid is distilled, or better, when the sodium salt is subjected to the
same treatment with sulphuric acid (l^ parts) : —

Cs(C02H)5 = C5H2(C02H)^ + 2CO2 and
C,H,(CO,H), = CeH2(C0),0, + 2H,0.

The acid results when the anhydride is boiled with water. It is also produced
by oxidizing durene and durylic acid' with potassium permanganate.

Pyromellitic acid is very similar to phthalic acid. It crystallizes in prisms,
containing 2H2O, and dissolves readily in hot water and alcohol. At 100° it
loses its water of crystallization, melts at 264°, and decomposes into water and the

dianhydride, Cj^HjOg = C5H2 ( r-o /O j 2, which sublimes in long needles,

and melts at 286°. The ethyl es/er, C5H^(C02.C2H5)^, melts at 53°.

Hydro- and iso-hydro-pyro-melliiic acids, CuHuOj = CgH2(H4)(CO,2H)^,
are obtained by the continued action of sodium amalgam upon the aqueous solu-
tion of the ammonium salt. The first results as a gummy mass upon evaporating
the ethereal solution ; it is very soluble in water. The second crystallizes with
2H2O, loses the same about 120°, melts near 200°, and decomposes into water,
carbon dioxide and Aj-tetrahydrophthalic anhydride (p. 788) [Annalen, 258, 205).
When heated with sulphuric acid both evolve CO2 and SOj and form trimellitic
and isophthalic acids.

By replacing the two/ hydrogen atoms in pyromellitic ester by O2 (by oxidizing
the diamido-compound with nitric acid) (Berichte, ig, 516) we obtain

Quinone Tetracarboxylic Ester, Cg(02)(C02.C2H5)4, crystallizing in
quinone-yellow needles, melting at i48°-l5o°. It is odorless, but sublimes quite
readily. Zinc reduces it in glacial acetic acid solution to

Hydroquinone Tetracarboxylic Ester, C^{OU.)^{CO^.Ci'H.^)^ or CjIIj
(02)(C02.C2H5)j, crystallizing in bright yellow needles, melting at 126-128°
[Berichte, 22, Ref. 289). Its solutions exhibit a beautiful blue fluorescence. It
dissolves with a yellowish red color in caustic soda. Nitric acid readily reoxidizes
it to the quinone-acid. In its entire deportment it shows great analogy to dioxy-
terephthalic ester (p. 794). In alcoholic splution it is reduced by zinc dust and
hydrochloric acid to

Quinone-tetrahydro-tetracarboxylic Ester, C^'^M^{<X)yZ^^i or

CHR— CHR,

/-Diketohexamethylene-tetracarboxylic Ester, COC )C0

[R = CO2.C2H5]. ^CHR-CHr/

It crystallizes from alcohol in colorless needles or prisms, contains water of crys-
tallization, softens at 110°, and then melts at 142-144°. Its deportment is per-
fectly analogous to that of succino-succinic ester. Ferric chloride imparts a
cherry-red color to its alcoholic solution. Bromine changes it again to hydro-
quinone tetracarboxylic ester.

2. Prehnitic Acid, CiuHgOg, (l, 2, 3, 4) results (together with mellophanic acid
and trirnesic acid) upon heating hydro- and isohydro-mellitic acid (p. 800) with
sulphuric acid, also by oxidizing prehnitol (p. 576) with potassium permanganate
[Berichte, 21, 907). It is very soluble in water, and crystallizes in warty masses
containing 2H2O, and melting at 238° with the formation of an anhydride. Its
salts crystallize with difficulty.

Sodium amalgam acting upon the ammonium salt solution, produces Hydro-

HEXABASIC ACIDS. 799

preknitic acid, Ci„Hi„Oj, an amorphous, very soluble mass, whicli yields
prehnitic acid and isophthalic acid when it is heated with sulphuric acid.

3. Mellophanic Acid, CgHj(C02H)4 (i, 2, 3, 5), is formed together with
prehnitic acid from hydro- and isohydromellitic acid, and also by the oxidation of
isodurene {Berichte, 17, 2517). It is also very soluble in cold water and crystal-
lizes in small prisms. It melts at 240° with decomposition into water, and an
anhydride melting at 238°.

Benzene Pentacarboxylic Acid, C5H(C02H)5, is produced by oxidizing
penta-methylbenzene with permanganate. It is an amorphous powder containing
six molecules of water.

HEXABASIC ACIDS.

Mellitic Acid, C^HeOu = CeCCOjH)^. This occurs in melliU
or honey-stone, which is found in some lignite beds. Honey-stone
is an aluminium salt of mellitic acid, CnjAl^Oij + iSHjO, and affords
large quadratic pyramids of a bright yellow color.

In preparing the acid, honeystone is boiled with ammonium carbonate, ammo-
nium hydroxide added, and the separated aluminium hydroxide filtered off. The
ammonium salt, C-^^^('i'iii^)fii^ -j- pH^O, crystallizes from the filtrate in large
rhombic prisms, which effloresce in the air. The free acid is obtained by con-
ducting chlorine into the aqueous solution of the ammonium salt {Berichle, 10,
560).

An interesting formation of mellitic acid is that whereby pure
carbon (graphite, charcoal, etc.) is oxidized with an alkaline solu-
tion of potassium permanganate. Another is when the carbon is
applied as positive electrode in electrolysis (^Berichte, i6, 1209 ; 17,
Ref. 701).

Mellitic acid crystallizes in fine, silky needles, readily soluble in
water and alcohol. It is very stable, and is not decomposed by
acids, by chlorine or bromine, even upon boiling. When heated it
melts and decomposes into water, carbon dioxide and pyromellitic
anhydride. It yields benzene when distilled with lime.

Mellitic acid forms salts with six equivalents of metal. The calcium and barium,
Ci2Ba30i2 + 3H2O, salts are insoluble- in water. The methyl ester, Cg
(COj.CHj)^, crystallizes in leaflets, melting at 187°; the ethyl ester melts at 73°.
Phosphorus pentachloride produces chloranhydrides.

The known amides of mellitic acid are Paramide and Euchroic Acid ; they ap-
pear in the dry distillation of the ammonium salt.

Paramide or Mellimide, CjjHjNjOg = Cg J ^-,„'^NH)3, is a white, amor-
phous powder, insoluble in water and alcohol. Heated to 200° with water, it is
converted into the tertiary ammonium salt of mellitic acid. The alkalies con-
vert paramide into euchroic acid.

Euchroic Acid, Cj jH^N^Og = C5 ^^q^NH^ j | ^qqjj, crystallizes in large

8oo ORGANIC CHEMISTRY.

prisms, and is sparingly soluble in water. Heated with water to 200° it yields
mellitic acid. Nascent hydrogen changes euchroic acid to euchrone, a dark blue
precipitate, which reverts to colorless jeuchroic acid upon exposure. Euchrone
dissolves with a dark red color in alkalies.

Sodium amalgam acting on ammonium mellitate produces Hydromellitic Acid,
Cj2Hg(Hg)Oi2. This is very soluble in water and alcohol, sparingly in ether,
and is indistinctly crystalline. It melts with decomposition. It is hexabasic, its
calcium salt being more soluble in cold than in hot water. If the acid be heated to
180° with concentrated hydrochloric acid, or if it be preserved, it is transformed
into the isomeric Isohydromellitic ^«V, Cj2Hi20i2. crystallizing in large, six-
sided prisms. Hydrochloric acid precipitates it from its aqueous solution.

When more highly heated with sulphuric acid, both acids yield prehnitic acid,
mellophanic acid and trimesic acid : —

and

C,H,(C02H)e = C,H2(C02H), + 3H2 + 2CO2,
CeH,(C02H), =CeH3(C02H)3 + 3H2 + 3CO,.

UNSATURATED COMPOUNDS.

The benzene derivatives previously studied contain saturated
side-chains, having carbon present in them. Perfectly analogous
compounds exist, in which unsaturated side-chains are present : —

CsH^.CHiCHj. CjH5.CH:CH.C02H.

Phenyl-ethylene, Phenyl-acrylic Acid,

Styrolene, Cinnamic Acid.

CeH^.CHj.CHiCHj CjHj.CHj.CHiCH.COjH

Phenyl-allyl. Phenyl-crotonic Acidi

CeH5.C=CH CeH5.C=C.C02H, etc.

Phenyl-acetylene. Phenyl-propiolic Acid.

Hydrogen converts them into the corresponding saturated com-
pounds.

Hydrocarbons.

Phenyl Ethylene, C8H8 = CeH5.CH:CH2, Styrolene, Vinyl-
benzene, occurs in storax (808) (1-5 per cent.), from which it is
obtained upon distillation with water. It is prepared by the action
of zinc dust and glacial acetic acid upon phenylacetylene. Sodium
and methyl alcohol will produce the same result (two hydrogen
atoms are added) (^Berichte, 21, 1184); by heating cinnamic acid
with lime or with water to 200° ; by the action of alcoholic potash
upon brom-ethyl benzene, and by the condensation of acetylene,
C2H2, upon application of heat. It is best obtained from /9-brom-
hydro-cinnamic acid (p. 757), which is immediately decomposed
by a soda solution into styrolene, carbon dioxide and hydrobroraic
acid {Berichte 15, 1983). It is a mobile, strongly refracting liquid,

NITRO-STYROLENES. 8oi

with an agreeable odor. Pure styrolene is optically inactive and
boils at 144-145° ; its sp. gr. = 0.925 at 0°.

Hydriodic acid converts styrolene into ethyl benzene, CgH5.C2H5 ; chromic
acid or nitric acid oxidizes it to benzoic acid.

Being an unsaturated compound, styrolene can directly take up two halogen
atoms, forming a/3-derivatives of ethylbenzene. It condenses with phenol, on
boiling with sulphuric acid, to oxy-diphenyl ethane, CgHj.CjH^.CgH^.OH {Be-
richte, 23, 3145).

Two series of mono-substitution products result whe_n the hydrogen of the side-
chain of styrolene suffers replacement : —

CjH^.CHiCHBr and CeH^.CBnCHj.

a-Brom-styvolene. j8-Brom-styrolene.

The aproducts arp derived (along with phenylacetaldehyde) from the phenyl-
nchlor (brom-) lactic acid (p. 776), upon heating with water. They are oils having
a hyacinth-like odor, boil undecomposed, and are far less reactive than the /3- pro-
ducts (similar to the halogen propylenes). a-Chlor-styrolene, CjHj.CHtCHCl,
is obtained from a-dichlor-ethyl-benzene (p. 586), and boils at 199°. a-Brom-
styrolene is formed from dibrom-hydrocinnamic acid (p. 757), by boiling with
water or digesting with a soda solution. It melts at 7° and boils at 220°. When
it is heated with water it yields phenyl-acetaldehyde, CgHj.CHj.CHO.

The ^-products result on heating styrolene chloride (-bromide), C5H5.C2H3
CIj, alone, with lime or with alcoholic potash. They do not distil undecom-
posed, and possess a penetrating odor, causing tears. They yield acetophenone,
C5H5.CO.CH3 (Berickte, 14, 323), when they are heated with water (to 180°)
or with sulphuric acid. ;3-Chlor-styrolene, CgH^.CChCHj, also results from
/3-dichlorethyl benzene (p. 586), when it is digested with alcoholic potash.
/3-Brom-styrolene yields phenyl acetylene with alcoholic potash at 120°; sodium
and carbon dioxide convert it into phenyl-propiolic acid.

Nitro-styrolenes.

a-Nltro-styrolene, CgH5.CH:CH(N02), phenylnitro-ethylene, is obtained by
boiling styrolene with fuming nitric acid, by heating benzaldehyde to 190° with
nitromethane, CH3(NOj), and ZnCl^ to 190° {Berichte, 17, Ref. 527), and by the
action of fuming nitric acid upon phenyl-isocrotonic acid (.5?r?V^i'^, 17, 413), as
well as by the action of NOj upon cinnamic acid, when the dinitro-compound,
C^Yi^.C^Yi^i^O ^)^.C0 ^Yi, formed at first, decomposes {Berichte, 18, 2438). It
possesses a peculiar odor, provoking tears, is readily volatilized in aqueous vapor,
and yields yellow needles, melting at 58°. Dilute nitric acid decomposes it into
benzaldehyde, carbon monoxide and hydroxylamine.

The nitro-styrolenes, C5H^(N02).CH:CH2 {0-, m- and /), containing the
nitro-group in the benzene nucleus, result from the nitrophenyl-j8-brom-laclic
acids (from the three nitro-cinnamic acids, p. 764), by the action of a soda solu-
tion in the cold, or upon boiling the /3-lactones obtained from the phenyl-brom-
lactic acids with water {Berichte, 16, 2213, 17, 595). Orthonitro-styrolene
melts at 13°, has a peculiar odor, and is colored blue by sulphuric acid. Meta-
nitro-styrolene melts at — 5°, para-nitro-styrolene at 29°; both have an odor
like that of cinnamic aldehyde.

o-Nitro-chlor-styrolene, C5H4(N02).CH:CHCl,is produced in the prepa-
ration of (?-nitro-phenyl-chlor-lactic acid and melts at 59° {Berichte, 17, 1070).

Dinitro-styrolene, C|,H^(N02).CH:CH(N02), results from ;»-a-dinitro-cin-
namic acid (p. 8 1 1 ) , by the splitting off of CO, ; it consists of yellow leaflets, melt-
ing at 199°. When it is heated to 100° with sulphuric acid it is broken up into
p nitrobenzaldehyde, carbon monoxide and hydroxylamine {Berichte, 17, Ref. 528).
66

8o2 ORGANIC CHEMISTRY.

Amido-styrolenes.

o-Amido-chlor-styrolene, C5H4(NH2).CH:CHC1, is obtained by reducing
»-nitro-chlor styrolene (see above) with tin and hydrochloric acid ; it consists
of white prisms. Heated to 170° with sodium alcoholate it yields indol, CgHjN.

/-Amido-styrolene, C|jH4(NH2).CH:CH2, is produced (together with p-
amido-cinnamic acid) in the reduction of ^-nilro-cinnamic ester ; it melts about
81°.

Phenyl Acetylene, CbHj.C ■ CH, acetenyl benzene, is produced
when /9-brom-styrolene and acetophenone chloride, CsHs.CClj.
CH3, are heated to 130° with alcoholic potash; also from phenyl-
propiolic acid (p. 814), on heating it with water to 120°, or upon
distilling the barium salt : —

CjHj.C iC.COjH = CjHj.ClCH + CO^.

It is a pleasant-smelling liquid, boiling at 139-140°. It forms
metallic compounds, like acetylene, with ammoniacal silver and
copper solutions : (C8H5)2Cu2, is bright yellow, (C8H5)2Ag2 -)- Ag^O
is white. The sodium compound, QHsNa, inflames in the air, and
with carbon dioxide it yields propiolic acid. When phenyl-acety-
lene is dissolved in sulphuric acid and diluted with water, it yields
aceto-phenone (see p. 726).

«-Nitrophenyl Acetylene, CgH^^^ -jL . This is produced on boiling nitro-

phenylpropiolic acid with water. It forms needles, melting at 81-82°, and yields
metalUc compounds with Cu and Ag.

/-Nitrophenyl Acetylene, CgH4(N02).C;CH, from /nitro-phenylpropiolic
acid, melts at 152°.

0- Amidophenyl Acetylene, C5H,(NH2)C • CH, is produced in the reduction
of o-nitrophenyl-acetylene with zinc dust and ammonia, or with ferrous sulphate
and potassium hydroxide, and in the decomposition of s-amido-phenylpropiolic
acid. It is an oil with an odor resembling that of the indigo vat. Sulphuric acid
and water convert it into o-amido-acetophenone.

Phenyl-diacetylene, CjHj.C i C.C| C.CgHj. This arises on shaking the cop-
per derivative of phenyl acetylene in the air (with some ammonia) or more readily
by the action of alkaline potassium ferricyanide {Berichte, 15, 57). It crystallizes
from alcohol in long needles, melting at 97°, combines with eight atoms of bro-
mine and does not form metallic derivatives. It is the parent hydrocarbon of

indigo-blue. Its «-dinitro-derivative, CgH^^' j;;--rv^l^ '^CgH^, obtained from

o-nitro-phenyl acetylene copper, by means of alkaline potassium ferricyanide and
melting at 212°, yields isomeric diisatogene, CigHjNjOj, with -sulphuric acid.
Ammonium sulphide at once converts Ijhis into indigo-blue, CigHijN^Oj
{Berichte, 15, 53).

Phenyl Allylene, CjHs.C-C.CHg, has been obtained from phenylbrom-
propylene, CgHj.CjHjBr (from a-methylcinnamic acid, p. 814). It is a liquid
with a disagreeable odor. It boils at 185° {Berichte, 21, 276).

PHENYL ACETYLENE. 803

Phenols.

1. Vinyl Phenols, CjH ^ ^h '• The methyl ethers of the 0- and /-com-
pounds, the vinyl anisols, C5H^(C2H3).O.CH3 have been obtained from the cor-
responding oxycinnamic acids. 0- Vinyl anisol boils about 198°, the ^-compound
at 205°. -

2. AUyl Phenols, CsH^/qI^s. Chavicol, the para-derivative, occurs in
the oil obtained from the leaves of Chavica Betle. It is a colorless oil with pecu-
liar odor and boils at 237°. It is not colored by ferric chloride. Its specific
gravity is 1.035 at 20°. Its alkyl ethers are produced by healing it with
caustic alkaU and alkyl iodides. Methyl Chavicol, Q.^Vi.^{C^Yi.^)O.CYi^, boils at
226° ; Its specific gravity is 0.986 at 22°. Ethyl Chavicol boils at 232° (Berichte,
22, 2739).

3. Propenyl Phenols, CgH^(C3H5),OH, containing the propenyl group—
CHiCH.CH,. Anol, the para-compound, may be obtained from its methyl ether,
anethol, by heating it together with caustic alkali to 200^-230°. It consists of
brilliant leaflets, melting at 92°- It decomposes upon distillation. Its methyl
ether, C^Yi^{<Z^'R^.O.CYi^, anethol, occurs in ethereal oils, from which it separates
in the cold in the form of white, shining scales, melting at 21° and boiling at 232°.
Anethol has been synthetically prepared from /-methoxyphenyl crotonic acid
{Berichte, 10, 1604). This would prove the group, C3H5, to be propenyl. A
rather remarkable formation of anethol is that resulting from the molecular re-
arrangement of methyl chavicol (see above), when the latter is heated with alcoholic
potash. In this change the allyl group is transposed to the propenyl group. All
ally I benzene derivatives sustain similar transformations into propenyl compounds
{Berichte, 23, 859) ; safrol is converted into isosafrol, methyl eugenol into methyl
isoeugenol, apiol into isapiol etc., etc. The propenyl derivatives are distinguished
from the allyl compounds by higher specific gravities, higher boiling points and
greater refractive power {Berichte, 22, 2747 ; 23, 862).

Chromic acid oxidizes anethol to anisic and acetic acids; less intense oxidation
produces anisic aldehyde.

4. Allyl Dioxybenzenes, C5H3(C3H5){OH)2. There are six possible iso-
merides; the (l, 3, 4)-compound is known in its ethers : —

fC^Hs (I) rCjHs (i)

C,H3 -^ O.CH3 (3) C,H3-^OH (3 CeH3

(oh (4) I.O.CH3 (4)

Eugenol. Chavibetol.

C^Ha (I)

0\ (3)

O^ (4)

Safrol.

Eugenol, Cj^HjjOj (Eugenic Acid), occurs in clove oil (from Caryophyllus
aromaticus), in all-spice (from Myrtus pimenta). On shaking oil of cloves with
alcoholic potassium hydroxide it solidifies to the potassium salt of eugenol ; this
is then pressed, washed with alcohol, and decomposed with an acid. It is an
aromatic oil, that boils at 247°, and is colored blue by ferric chloride. Potassium
permanganate oxidizes it to homovanillin, vanillin and vanillinic acid. It breaks
down into acetic acid and protocatechuic acid, CgH3(C02H)(OH)2 (i, 3, 4),
when fused with potassium hydroxide (p. 779).

Methyl Eugenol, CgH3(C3H5)(O.CH3)2, is formed when eugenol is heated
together with caustic potash and methyl iodide. It is a liquid, boiling at 237-239°.
Chromic acid oxidizes it to dimethyl protocatechuic acid. The compound, C3H3
(C3H5)(O.CH3)2, the chief constituent of the oil of asarum, appears to be identi-
cal with methyl eugenol {Berichte, 22, 3172).

Chavibetol, C6H3(C3H5)(OH)(O.CH3) (i, 3, 4) (see above), occurs with
chavicol in oil of betel {Berichte, 23, 859), and is isomeric with eugenol.

8o4 ORGANIC CHEMISTRY.

Safrol, CioHioOj = CeH3(C3H5) ( /CHj J (see above), is the methylene

ether of allyl dioxybenzene. It is present in the oil of Sassafras officinalis and
Ilicium religiosum, hence called Shikimol. When the oil is chilled it separates
as a white crystalline mass, melting at -f 8°- Potassium permanganate oxidizes it
to piperonal and piperonylic acid (Berichte,^\, 474; 23, 864).
5. Isoeugenol, ethyl isochavibetol and isosafrol are derivatives of —
Propenyl Dioxybenzene, C5H3(C3H5)(OH)2 (containing the propenyl
group — CH:CH.CHg), isomeric with allyl dioxybenzene. These can be formed
by the rearrangement of corresponding allyl derivatives upon heating the latter
vi'ith alcoholic potash.

Isoeugenol, CgH3(C3H5)(O.CH3).OH, is formed when homoferulic acid is
distilled with lime. It is an oil boiling at 260° (Berichte, 23, 860).

3H,) (°)CH,)

Isosafrol, €5113(03115) I /CHj j, is obtained from safrol by heating it

with sodium, or more readily by boiling it with alcoholic soda {^Berichte, 23, 1 160).
It is an oil boiling at 246-248°. Chromic acid oxidizes it chiefly to piperonal
(artificial heliotropine). Sodium and alcohol reduce it to dihydrosafrol and
zw-propyl phenol.

6. Asarone, CjjHjgOj := C5Hj(C3H5)(O.CH3)3, is a derivative oi fropenyl
trioxybenzene. It is the solid component of the oil from Asarum europcaum,
■whereas the liquid portion consists of methyl eugenol and terpenes (^Berichte, 21,
615, 1057; 22, 3172). Asarone forms monoclinic prisms, melting at 61° (67°),
and boils at 295°. Potassium permanganate oxidizes it to tri-methoxybenzoic
acid, C5H2(O.CH3)3.C02H, which yields carbon dioxide and the tri-methyl ether
of oxyhydroquinone upon distillation with lime {Berichte, 23, 2294).

7. Apiol, Cj^HijO^ = C5H(C3H5)(02:CH2)(O.CH3)2, is a derivative of allyl
tetroxybenzene, CgH(C3H5)(OH)4 — its methylene dimethyl ester. It occurs in
parsley seeds and is volatile in a current of steam. It crystallizes in long needles,
with a slight parsley odor. It melts at 30°, and boils at 294°- It dissolves with
a blood-red color in oil of vitriol. Potassium permanganate oxidizes it to apiol
aldehyde and apiolic acid, CgH(02:CHj)(O.CH3)2.C02H, melting at 175° {Be-
richte, 21, 1624). When heated with dilute sulphuric acid to 140° apiolic acid
breaks down into carbon dioxide and apione, the methylene dimethyl ether of
apionol, i. e., of tetroxybenzene {Berichte, 23, 2293).

Boiling alcoholic potash converts apiol into its i.someric propenyl-AemsXvve —
Isapiol (p. 803). The latter forms leaflets, melts at 56°, and boils at 304°. Potas-
sium permanganate or potassium bichromate and sulphuric acid convert it into
apiol aldehyde {Berichte, 23, 2293).

Alcohols and Aldehydes.

Styryl Alcohol, CgHj„0 = CeH5.CH:CH.CH2.0H (Styrene, Cinnamyl Alco-
hol), is obtained by saponifying styracine, its cinnamic ester, with potassium
hydroxide. It crystallizes in shining needles, is sparingly soluble in water, pos-
sesses a hyacinth- like odor, melts at 33°, and distils at 250°. When carefully
oxidized it becomes cinnamic acid, but in case the oxidation is energetic, benzoic
acid is the product. In the presence of platinum sponge it oxidizes in the air to
cinnamic aldehyde. It yields cinnamic ether (CgHj,)20 — a mobile oil — when it
is digested with boric anhydride.

BENZYLIDENE ACETONE. 805

Cinnamic Aldehyde, CgHjO, is the chief ingredient of the
essential oil of cinnamon and cassia (from Persea Cinnamonum and
Persea Cassia). It is obtained by the oxidation of cinnamic alco-
hol, by dry distillation of a mixture of calcium cinnamate and for-
mate, and by saturating a mixture of benzaldehyde and acetalde-
hyde with hydrochloric acid, or by the action of caustic soda
(pp. 716, 806):—

CeHj.COH -1- CH3.COH = CeH5.CH:CH.CHO + H^O.

Sodium ethylate is preferable to aqueous or alcoholic sodium
hydroxide for condensation purposes {Berichte, 20, 657).

To obtain the aldehyde from cinnamon oil, shake the latter with a solution of
primary sodium sulphite, wash the crystals which separate with alcohol, and decom-
pose them with dilute sulphuric acid [Berichte, 17, 2109). Cinnamic aldehyde
is obtained synthetically by allowing a mixture of benzaldehyde (lo parts), acet-
aldehyde (15 parts), water (900 parts), and 10 per cent, ordinary sodium hydroxide
to stand and then extracting with ether [Berichte, 17, 21 17).

Cinnamic aldehyde is a colorless, aromatic oil, which sinks in
water and boils at 247° ; it distils readily in aqueous vapor. When
exposed to the air it oxidizes to cinnamic acid, and in other
respects shows all the properties of the aldehydes.

Dry ammonia converts it into the crystalline base Hydro-cinnamide,
[C^^^^ (p. 715) [Berichte, 17, 2110).

Its phenylhydrazone, CaH5.CH:CH.CH(N2H.CgH5), melts at l68°.

Nitrocinnamic Aldehydes, C6Hi(N02).CH:CH.CHO. Ortho- and para-
derivatives are produced by the nitration of cinnamic aldehyde when added to a
cold mixture of sulphuric acid (500 gr.) and nitre (20 gr). They can be separated
by means of sodium bisulphite [Berichte, 18, 2335). The three isoiiierides can be
synthesized by the condensation of the nitrobenzaldehydes with acetaldehyde, in-
duced by caustic soda. By using dilute alkali nitrophenyl- lactic aldehydes are
the first products; heated with acetic anhydride they become nitrocinnamic alde-
hydes.

The ortho acid crystallizes from hot water in long needles, melting at 270°
(Preparation, Berichte, 18, 2335). The meta acid melts at 1 15°, the/ara at 142°.
See Berichte, 20, 193, for the cumaric aldehydes.

Ketones.

Benzylidene Acetone, CeHs.CHrCH.CO.CHs, Benzal Ace-
tone, Cinnamyl-methyl ketone, is obtained on distilling calcium
cinnamate and acetate. It is very easily procured by the condensa-
tion of benzaldehyde with acetone (p. 716) on shaking with dilute
sodium hydroxide {Annalen, 223, 139) : —

CeHj.CHO -f CH3.CO.CH3 = C^Hj.CHiCH.CO.CHj + H^O.

8o6 ORGANIC CHEMISTRY.

It separates as a thick oil which solidifies after distillation. It has
a peculiar odor, crystallizes in brilliant quadratic plates, melts at
41-42°, and boils near 262°. It dissolves in sulphuric acid with
an orange-red color, and combines with sodium bisulphite.

Phenylhydrazine converts it into a hydrazone, CeHj. CH:CH.
C(HN2.C6H5).CH3J the rearrangement of this compound gives rise
to diphenylmethylpyrazoline {Berichte, 21, 1097). Boiling sodium
hypochlorite converts benzalacetone into cinnamic acid. Chloro-
form is eliminated at the same time.

The nitration of benzalacetone with sulphuric acid and nitric acid in the cold
produces the orlho- and para-nitro-derivatives ; these can be separated by means
of alcohol (Berichfe, 16, 1954).

o-Nitrobenzal Acetone, CsH4(N02).CH:CH.CO.CH3, forms warty crystals,
melting at 59°. The action of alcoholic potash, hydrochloric acid, and then
sodium hydroxide produces indigo (see below). a-Methyl-quinoline results from
it by reduction with stannous chloride and hydrochloric acid (p. 755 and p. 721) : —

,CH:CH.C0.CH3 .CH:CH

CsH / = C,H ,( I + H,0.

^NHj ^N : C.CH3

a-Methyl Quinoline.

/-Nitrobenzal Acetone, melts at 254° {Berichle, 16, 1970).

Dibenzylidene Acetone, p^u^ ftriptr /CO (Cinnamone), is produced by

the condensation of benzylidene acetone (see above) with benzaldehyde, caused
by the action of sodium hydroxide in alcoholic solution. It crystallizes in bright
yellow needles, and melts at 112°.

Benzylidene Acetophenone, CsH5.CH:CH.CO.CgH5, is formed when
benzaldehyde and acetophenone are allowed to stand together with sodium ethylate
(Berichte, 20, .657). It crystallizes in prisms or plates, melting at 58° and distilhng
about 346°.

Acids.

In addition to the general methods for preparing aromatic acids
(P- 739) and for the conversion of saturated into unsaturated acids
(p. 234), we can also prepare the unsaturated aromatic acids syn-
thetically, by the following methods : —

(i) By the condensation of aromatic aldehydes with the fatty acids
(p. 716), effected by heating with the chlorides of the acids, e.g.,
CH3.COCI (Bertagnini), or with the free acids in the presence of
zinc chloride or hydrochloric acid (SchifF) : —

CsHj.CHO + CHs.CO^H = CeH^.CHrCH.CO^H + H^O ;
Benzaldehyde. Acetic Acid. Cinnamic Acid,

Phenylacrylic Acid.

or, better, with a mixture of the sodium salts and the anhydrides of
the fatty acids (Perkin).

BENZYLIDENE ACETONE. 807

In the last case the reaction occurs between the aldehyde and the sodium salt
{Berichte, 14, 2110: Anna/en, 227, 48; compare Berichte, 19, Ref. 346), when,
by the aldol condensation, we obtain a /3-oxyacid : — ,

CuHj.CHO + CH3.C02Na= C(.H5.CH(OH).CH2.C02Na,

j8-PhenylhydracryIic Acid.

which is then deprived of water by the acid anhydride: —

C5H5.CH(OH).CH2.C02H = CjHs.CaCH.CO^H + H^O.

All aromatic aldehydes (aldehyde phenols, aldehydic acids), react similarly
with the homologous fatty acids and with many other compounds (p. 716). Thus,
phenyl-crotonic acid, CgH^.CgH^.COjH, is produced from benzaldehyde by
means of the sodium salt and the anhydride of propionic acid, and the coumaric
acids, C5H^(OH).C2H2.C02H, etc., from the oxybenzaldehydes, C6H4(OH).
CHO, with acetic acid. With the higher fatty acids the condensation occurs in
such a manner that the two hydrogen atoms are withdrawn from the carbon atom
in union with carboxyl {Annalen, 204, 187, and 208, 121) : —

C5H5.CHO + CH3.CH2.CO2H = CeH5.CH:C(^^Q 3jj -f- H^O.
Propionic Acid. Phenyl-meth-acrylic Acid.

Similarly, phenyl-paraconic acid (p. 793), and (by withdrawal of COj) phenyl-

isocrotonic acid (p. 813) are obtained from benzaldehyde with sodium succinate

and acetic anhydride. Benzalmalonio acid, CsH5.CH:C(C02H)2; andlcinnamic

, acid are formed from benzaldehyde and malonic acid. Glacial acetic acid may

be employed instead of acetic anhydride {Berichte, i5, 1436, 2516).

(2) By condensation of ben^aldehydes with fatty acid esters, by means of sodium
ethylate or metallic sodium; esters of the unsaturated acids are produced (Claisen)
(p. 716) {Berichte, 23, 976) : —

CuHj.CHO + CH3.CO.O.C2H5 = CgHs.CHrCH.COj.CaHs + H^O.

I. Phenyl Acrylic Acids, CgHs.CjHj.COjH.

According to the structural theory, there are two possible isomerides, with this
formula : —

(I) CeH,.CH:CH.CO,H and (2) C^H^.C^^^^^^g.

J3-Phenylacrylic Acid. a-Phenylacrylic Acid.

The first belongs to cinnamic acid ; the second to atropic acid (p. 813). Cinna-
mic acid, in accordance with the stereochemical representations, can occur in two
stereochemical forms (similar to crotonic acid (p. 238) and fumaric and maleic
acids (p. 425) : —

CH.C5H5 CjHj.CH

(I) II (2) II

CH.COjH CH.COjH.

The first is the plane-symmetric arrangement ; the second, the axially-symmetric
or preferable configuration (p. 52). Wislicenus gives cinnamic acid the first
formula. The formation of the acid by; the reduction of phenyl- propiolic acid

8o8 ORGANIC CHEMISTRY.

argues in favor of this view {Berichte, 22, 1181). However, there is the opposing
fact that the recently discovered isocinnamic acid (p. 812), which must be given
the axially-symmetric formula (2) is less stable than ordinary cinnamic acid and
is readily converted into it. Furthermore, these stereochemical ideas have been
proved insufficient by the discovery of a third ;3-phenylacrylic acid — a//»-cinnamic
acid (p. 813).

Cinnamic Acid, QHsO^ = CeHj.CHiCH.CO.H, /?-Phenyl-
acrylic acid {Acidum cinnamylicum) , occurs in Peru and Tolu
balsams (p. 742), in storax and in some benzoin resins. It results
in the oxidation of its aldehyde or its alcohol, by the condensation
of benzaldehyde with sodium acetate, by the decomposition of
benzal malonic acid, and by the reduction of phenylpropiolic acid
with zinc dust and glacial acetic acid {^Berichte, 22, 1181).

Cinnamic acid is obtained either synthetically from benzaldehyde, or from
storax [Styrax officinalis) — the pressed-out, thick sap of the bark of Liquidambar
orieniale. This contains, besides a resin, some free cinnamic acid and slyrolene,
CgHg, but chiefly j/j/?-a«W (cinnamic cinnamate and phenyl-propylic cinnamate
p. 711). The styrolene is distilled off upon boiling with water. The residue is
boiled with a soda solution, in order to remove the cinnamic acid ; cold alcohol
will extract the resin from what remains and only styracine is left. To obtain the
cinnamic acid, storax is boiled for some time with sodium hydroxide, when the
cinnaniyl alcohol which is formed will distil over. Hydrochloric acid precipitates
cinnamic acid from the solution. It is purified by distillation or crystallization
from benzine (comp. Annalen, 188, 194).

To get the acid from benzaldehyde, a mixture of the latter (3 parts) with
sodium acetate (3 parts) and acetic anhydride (10 parts), i9 boiled for several
hours, water is then added and the acid dissolved in soda {Berichte, 10, 58). A
more convenient procedure consists in heatinig benzalchloride, CgH5.CHCl2 (l part)
with sodium or potassium acetate (2 parts) to 200°.

Cinnamic acid crystallizes from hot water in fine needles, from
alcohol in thick prisms, is odorless, melts at 133°, and when quickly
heated distils near 300° with almost no decomposition. It is
soluble in 3500 parts of water of 17°, and readily in hot water.

The cinnamates are similar to the benzoates ; ferric chloride produces a yellow
precipitate in their solutions. In chemical character cinnamic acid closely resem-
bles the acids of the acrylic acid series. Fusion with caustic potash decomposes it
into benzoic and acetic acids (p. 236) : —

CeHs.CHiCH.COjH + 2KOH = C^Hs.COjK + CHj.COjK + Hj.

Nitric acid and. chromic acid oxidize it to benzaldehyde and benzoic acid. When
heated with water to 180-200°, or with lime, it breaks up into COj and styrolene.
The acid of distyrene, CijHjjOj, and distyrolene are produced on heating with
sulphuric acid.

The ethyl ester o{ cmoixaxc acid, C9H,02(C2H5), is a liquid, boiling at 271°-
It readily combines with bromine (dissolved in CSj) to form the dibromide,

CINNAMIC ACID. 809

CgHjBrjOj.CjHj, melting at 69°. Like the esters of other unsaturated acids it
combines with sodmalonic ester and sodacetoacetic ester (^Berichte, 20, Ref. 258,
504). The methyl ester melts at 33.5°, and boils at 263°- Cinnameln, contained
in Tolu and Peru balsams, consists of benzylic benzoate and cinnamate. It is
obtained artificially by heating sodium cinnamate with benzylic chloride. It pos-
sesses an aromatic odor, crystallizes from alcohol in small, shining prisms, melting
at 39°, and boiling about 320°.

Styracine, present in storax, is the cinnamic ester of cinnamyl alcohol, CgH,.
CO.O.CgHg (p. 808). It is best obtained fronr storax, by digesting the latter at
30° with dilute sodium hydroxide, until the residue (styracine) becomes colorless.
It crystallizes from hot alcohol in fine needles, melting at 44°, and decomposes
when distilled.

As cinnamic acid is unsaturated it is capable of taking two additional affinities.
Hydrogen converts it into hydrocinnamic acid ; chlorine produces dichlor-, brom-
ine dibrom-hydrocinnamic acid {cinnamic dibromide), and hydrobromic and
hydriodic acids convert it into /3-brom- and iodo-hydro- cinnamic acids (p. 757).
Hypochlorous acid changes it to phenyl-a-chlor-lactic acid (p. 776).

The halogen cinnamic acids (0-, m-, and/-), having the substitutions in the ben-
zene nucleus, are obtained from the three diazocinnamic acids, CgH^ (N^X).
CjHj.COjH, when they are digested with the haloid acids, and in this way all nine
chlor-, brom-, and iodo-cinnamic acids, CjHjX.CjH^.CO^H, have been prepared
{Berichte, 15, 2301, 16, 2040).

Two possible isomerides can exist for each monohalogen cinnamic acid or
phenylhaloid acrylic acid, with the substituting group in the side-chain : —

CsH^.CHiCCl.COjH and CsHs.CClrCH.CO^H.

a-Chlor-cinnamic Acid. P-Chlor-cinnamic Acid.

However, three (or four) isomeric chlor- and brom-cinnamic acids are known.
We therefore have relations to deal with similar to those observed with fumaric
and maleic acids (p. 425)- Apparently, the a- and /3-acids possess the same
structural formula (i), and the so-called ;8-acid bears the same relation to the
a-acid that maleic bears to fumaric acid. Following the suggestion of Michael
we designate the /3-chlor- and brom-acids, the allo-a-haloid cinnamic acids, and the
two recently discovered chlor- and brom-cinnamic acids (y and S) are termed j3-
and allo-/3-acid {^Berichte, 20, 550; 22, Ref. 741). Erlenmeyer regards /3-brom-
cinnamic acid as corresponding to isocinnamic acid, as the latter is produced by
the reduction of the former [Berichte, 23, 3130). Until these relations are more
fully determined the old designations o, p, etc., will be continued.

Two chlorcinnamic acids are obtained from a/3-dichlorhydrocinnamic acid
by the action of alcoholic potash {Berichte, 15, 788).

a-Chlor-cinnamic Acid is produced synthetically in the condensation of ben-
zaldehyde and sodium chloracetate, when heated to 1 10°, with acetic anhydride
{Berichte, 15, 1945) :—

C4H5.CHO -I- CHjCl.COjNa = CeHj.CHiCCl.COjjNa + H^O;

and from phenyl-a-chlorlactic acid (p. 776) by the withdrawal of water on heating
68

8lO ORGANIC CHEMISTRY.

with acetic anhydride {Berichte, 16, 854). It melts at 137°; its alkali salts are
very readily soluble in water.

jS-Chlor-cinnamic Acid melts at 111°; upon distillation it suffers a very slight
transposition into the a-acid.

y-and-(5 Chlor-cinnamic Acids (/3-and allo^-acid) are produced by the addi-
tion of hydrogen chloride to phenyl- propiolic acid (p. 814). The first melts at
132°; the second at 142° {Berichte, 22, Ref. 741).

The brom-cinnamic acids are prepared like the chlor-cinnamic acids, by
boiling the a/3-dibrom-hydro cinilamic acid with alcoholic potassium hydroxide.
They can be separated by means of their ammonium salts, or by the fractional
precipitation of the salt mixture [Annalen, 154, 146).

a-Brom-cinnamic Acid, the ammonium salt of which dissolves with difficulty,
and is first precipitated, crystallizes from hot water in fine needles, melting at 131°,
and then sublimes. Its ethyl ester boils at 290°. Concentrated sulphuric acid
converts it into benzoyl acetic ester {Berichte, ig, 1392).

j3-Brom-cinnamic Acid crystallizes from hot water in shining leaflets, melting
at 121°. Its alkali salts are deliquescent. It changes to the a-acid if heated with
hydriodic acid, and if distilled or heated for some time to 150-180°- It sustains
a like transposition if converted into its ethers by alcohol and hydrochloric acid;
the ester of the a-acid is then formed. Consult Berichte, 20, 551, 1386, upon the
methyl and ethyl esters of a-and ;8-brom-cinnamic acids. Both acids yield phenyl-
propiolic acid when boiled with alcoholic potassium hydroxide.

7-Brom-cinnamic Acid, C5ll5.CBr:CH.C02H(?) (see above), is produced by
the addition of hydrobromic acid to phenyl-propiolic acid, CsHj.CiC.COjH
{Berichte, ig, 1936). A fourth acid is produced simultaneously; it is very similar
to a-brom-cinnamic acid {Berichte, 20, SS3). It dissolves with difficulty in cold
alcohol, and crystallizes in needles, melting at 158.5° (153.5°).

The addition of two bromine atoms to phenyl-propiolic acid produces two a/3-
dibrom-cinnamic acids, CjHj.CBriCBr.COjH, Called a- and /3-. The a- melts at
139°, and the ^- at 100°. The first passes readily into the second {Annalen, 247,

Nitro-cinnamic Acids, C6H4(N02).CH:CH.C02H.

The introduction of cinnamic acid into nitric acid of specific gravity 1.5 leads to
the formation of the ortho- (60 per cent.), and para-nitro acids, of which the former
is the more easily soluble in hot alcohol. To separate them cover the acid mixture
with 8-10 parts of absolute alcohol, and conduct hydrochloric acid gas rapidly into
the liquid, until complete solution ensues. On cooling the para-ether separates.
The mother liquor is evaporated, and the ortho-ether recrystallized from ether
{Annalen, 212, 122, 150). The esters are saponified with sodium carbonate, or
by heating with a mixture of 10 parts sulphuric acid, water and glacial acetic acid
(equal parts), to 100°, or with water and sulphuric acid {Annalen, 221, 265).

The three isomeric acids can be prepared from the corresponding nitro-benzal-
dehydes by means of sodium acetate, etc.

(?-Nitro-cinnamic Acid is insoluble in water, crystallizes from
alcohol in needles, melting at 240°, and sublimes with partial de-
composition. It colors concentrated sulphuric acid dark blue upon
warming. Chromic acid oxidizes it to nitro-benzoic acid, and
potassium permanganate converts it into ^-nitrobenzaldehyde
(p. 719). Bromine unites with it with difficulty, yielding the di-

AMIDO-CINNAMIC ACID. 8ll

bromide, C6H4(N02).CHBr.CHBr.C02H, melting at i8o°, and
forming o-nitrophenylpropiolic acid (p. 815), and then isatin when
digested with sodium hydroxide. Indol results upon heating it
with sodium hydroxide and zinc dust.

The ethyl ester of o-nitrocinnatnic acid is very soluble in cold alcoliol, crystal-
lizes in needles or prisms, and melts at 44°. It yields carbostyril (p. 812), if
digested with aqueous ammonium sulphide, and oxy-carbostyril if the solution be
alcoholic. Tin and hydrochloric acid reduce it to o-amido-cinnamic ester (see
below), and zinc dubt and hydrochloric acid to hydrocarbostyril (p. 810). The ester
readily unites with bromine, yielding the dibromide, Cj.H4(N02).CHBr.CHBr.
COj.C^Hj, melting at (110°) 71° [Annalsn, 212, 130), and serving for the
preparation of o-nitrophenylpropiolic acid (p. 815).

ffi-Nitro-cinnamic Acid has been obtained from /«-nitrobenzaldehyde, and
consists of bright, yellow needles, melting at 197°. Oxidation changes it to
»2-nitrobeuzoic acid ; its ethyl ether melts at 79°.

/-Nitro-cinnamic Acid (see above) crystallizes from alcohol in shining
prisms, and melts at 286°. Chromic acid oxidizes it to/-nitrobenzoic acid, while
sulphuric and nitric acid convert it into /-nitrobenzaldehyde (p. 720). Its ethyl
ester is almost insoluble in cold alcohol and ether, forms fine needles, and melts at
138°

/a-Dinitro-cinnamic Acid, CgHj(N02).CH:C(N02).C02H, is obtained from
/-nitrocinnamic acid by the action of sulpfiuric and nitric acids at — 10°. It is
very unstable, and at 0° decomposes into carbon dioxide and dinitroslyrolene
(p. 801). Its ethyl ester, from /-nitrocinnamic ester, melts at 110°, and upon
reduction yields /-amidophenyl alanine (p. 758). ?«-Nitrocinnamic acid deports
itself very much like the /-acid [Berichte, 18, Ref. SS4)-

Amido-cinnamic Acids.

a Amido-cinnamic Acid, C5H5.CH;C(NH2).C02H, obtained from benzoyl-
amido-cinnamic acid [Berichte, 17, 1620}, is very similar to phenyl-alanine (p. 758),
decomposes at 240° with formation of phenyl vinyl-amine, CgH5.CH:CH(NH)j,
and by reduction yields phenyl-alanine.

The amido-cinnamic acids, C6H4(NH2).CjH2.C02H, with the
substitutions in the benzene nucleus, can be obtained from the three
nitro-cinnamic acids by reduction with tin and hydrochloric acid.
There is greater advantage in reducing them with iron sulphate in
alkaline solution (p.- 592).

To prepare the «-amido-acid add an excess of ammonia and the ammoniacal
solution of o-nitrocinnamic acid (5 grs.) to the boiling solution of green vitriol
(50 grs.), continue boiling on a sand-bath and let the brownish- black precipitate
of ferroso-ferric oxide subside. The solution should smell of ammonia, and be
perfectly clear, and pure yellow in color, and if this be not the case add ammonia
and apply heat. Concentrated hydrochloric acid is gradually added to the filtered
solution of the ammonium salt of the amido-acid, as long as the yellow acid is
precipitated [Berichte, 15, 2294). For the reduction by means of ferrous sulphate
and baryta water, see Annalen, 221, 226.

8l2 ORGANIC CHEMISTRY.

tf-Amido-cinnamic Acid separates in fine yellow needles,
when hydrochloric acid is added to solutions of its salts. It melts
at 158-159°, evolving gas. It is readily soluble in hot water, in
alcohol and ether ; the solutions exhibit a greenish-blue fluorescence.
It yields ortho-coumaric acid when diazotized and boiled with
water. The splitting-off of water causes it to pass into its lactime —
the so-called carbostyril (a-oxyquinoline) — (p. 755) : —

CaH /^^^C"-^°-°" = C,H /^"/^ + H,0.
\^"2 \N:C(0H)

a-Oxyqui noline.

This anhydride formation ensues on protracted boiling with hydrochloric acid,
more rapidly on heating to 130° with hydrochloric acid, or upon heating the
acetyl derivative of the o-amido-acid. When the acid is heated alone (unlike the
o-amido-hydro-cinnamic acid, p. 757), it does not yield an anhydride (similar to
ortho-coumaric acid).

The ethyl ester was first obtained by reducing o-nitro-cinnamic ester with tin
and hydrochloric acid in alcoholic solution [Berichte, 15, 1422) ; a simpler method
consists in conducting hydrochloric acid gas into the alcoholic solution of the free
amido acid, evaporating and precipitating the aquebus solution with sodium acetate,
when the ether will separate in fine yellow needles, melting at 77°. Its solutions
show an intensely yellowish-green fluorescence. If digested at go° with alcoholic
ZnClj it will yield ethyl-oxy-quinoline (see above) ; and oxy-quinoline if evapo-
rated with hydrochloric acid.

Ethyl Amido-cinnamic Acid, CgH Z^^'^^^^^^, is obtained when

ethyl iodide and potassium hydroxide act upon o-amido-cinnamic acid. It melts
at 125°, and forms a nitroso-hody which, by reduction and the splitting-off' of
HjO, yields an isindazole compound (p. 841).

The diazo-derivative of the amido-acid unites with sodium sulphite and forms

o-Hydrazine-cinnamic Acid, CgH / j^^j^ NH ' ^^''^'^ °^ application of
heat yields Indazole, CjHgNj (p. 841).

z«- and /-Amido-cinnamic Acids, CeH4.(NH2).C2H2.C02H, are similarly
formed from m- and /nitrocinnamic acids by reduction with green vitriol and
ammonia (Berichte, 15, 2299) ; the first melts at 181°, the second at 176°. The
halogen cinnamic acids (p. 809) result upon boiling the diazo-compounds with the
haloid acids; and when water is employed m- and/-coumaric acids result.

2. Isocinnamic Acid, CgHj.CHiCH.COjH (p. 807), is found in the acid
mixture — truxillic, cinnamic and benzoic — that results upon decomposing cocaine
(for the preparation of ecgonine). It is distinguished from the associated acids
by greater fusibility and solubility {Berichte, 23, 141, 512). It is not present in
the cinnamic acid obtained synthetically from oil of bitter almonds. It has been
artificially prepared from ^-bromcinnamic acid by replacing its bromine {Berichte,
23. 3131)-

It is separated from the aqueous solution of its salts in the form of an oil, dis-
solves very easily in the common solvents, crystallizes from petroleum ether in
brilliant crystals, melting at 45-47°. and when absolutely pure at 57°. It boils at
265°, changing at the same time to ordinary cinnamic acid, boiling at 300°.

It is also transformed into the latter by solution in sulphuric acid, or by boiling
with iodine and carbon disulphide. A determination of its molecular weight by

AMIDO-CINNAMIC ACID. 813

the method of Raoult leads to the simple molecular formula. The isocinnamic
acid derivatives, the salts excepted, are mainly identical with those of ordinary cin-
namic acid.

3. AUo-cinnamic Acid, CgHs.CHiCH.COjH, occurs with the iso-acid in
the acid mixture in which the latter is present. It is not as soluble in ligroine
and melts at 68°. Its salts differ from those of the other two cinnamic acids.
Potassium permanganate oxidizes the alio- and isocinnamic acids to benzalde-
hyde. Direct sunlight converts iso- and allo-cinnamic acids into ordinary cin-
namic acid (Berichte, 23, 2510).

4. In addition to the three monomolecular cinnamic acids there are several
(probably four) —

Dicinnamic Acids, (CgHjOj)^, or Truxillic Acids. They probably originate
from tetramethylene, C^Hj, and correspond to the formulas : —

C.Hj.CH — CH.CO,H

II ^ ■

C„H.;.CH — CH.CO,H HOX.CH — CH.C„H,

II and - -|

— __. C.CH — <

Their differences are based upon stereochemical isomerisms [Berichte, 23,
2516).

5. Atropic Acid, CgHgOj, a-Phenylacrylic Acid, results from atropine,
tropic acid and atrolactinic acid (p. 775) when they are heated with concentrated
hydrochloric acid or with bartya water (Annalen, 195, 147). It crystallizes from
hot water in monoclinic plates, is sparingly soluble in cold water, easily in ether,
carbon disulphide and benzene ; melts at 106°, and distils with aqueous vapor.
Chromic acid oxidizes it to benzoic acid ; sodium amalgam converts it into hydro-
atropic acid, and hydrochloric and hydrobromic acids change it to a- and /3-halogen
hydro atropic acids (p. 759).

Atropic acid sustains the same relation to cinnamic acid as hydro-atropic to
hydro-cinnamic acid or methyl acrylic acid to ordinary crotonic acid (p. 238) : —

C6H5.CH:CH.C02H CeHj.CHj.CHij.COjH

Cinnamic Acid. Hydrocinnamic Acid.

Atropic Acid. Hydroatropic Acid.

Like all unsaturated acids when fused with caustic alkali, it splits at the point
•of double union, and yields formic and a-toluic acids, C5H5.CH2.CO2H, whereas
cinnamic acid decomposes into benzoic and acetic acids.

Protracted fusion, or heating with water or hydrochloric acid (in small quantity,
even upon recrystallization), converts atropic acid into two polymeric isotropic
acids (CgHgOj), (melting at 237° and 206°) which are very sparingly soluble,
and no longer capable of yielding additive products.

2. Acids, CjqHioOj.

Phenyl- iso-crotonic Acid, CgHj.CHiCH.CHj.COjH, is produced on heating
benzaldehyde with sodium isosuccinate. Phenyl-paraconic acid (p. 793) is pro-
duced at first, but this then parts with carbon dioxide. The acid melts at 86°, and
when boiled yields water and a-naphthol. It unites with hydrogen bromide, forming
phenyl-7-brombutyric acid, which yields phenylbutyro-lactone (p. 777) with a soda
solution. Boiling dilute sulphuric (I part : 2 parts water) converts it directly into
phenylbutyrolactone (p. 352).

8l4 ORGANIC CHEMISTRY.

Phenyl-methacrylic Acid, CgHj.CHiCc^^Q'jj, is obtained from benzalde-

hyde and sodium propionate, as well as by the action of sodium upon propionic
benzyl ester (^fWir,4/^ 20, 617). It crystallizes from water in long needles, that
melt at 78°, and boil at 288° Sodium amalgam converts it into phenylisobutyric
acid. Bromine in the presence of alkali converts the amide of the latter into
phenylisopropylaraine, aH5.CHj.CH(CH3).NHj (p. 160) {Berichte, 20, 618).

r^W (""FT
Methyl Atropic Acid, Z^yCi:'Qir^ '^ ^ is obtained from phenyl-acetic

acid, CeHs.CHj.COjH, and acetaldehyde. It melts at 135°.

Methyl Cinnamic Acids, C„H /^^•^^•^°2^. The three isomerides, 0-,

m- and p-, have been prepared from the corresponding toluic aldehydes by means
of sodium acetate. The ortko melts at i59°,the/ara at 197° {Berichle, 23, 1029,
1033) and the meia at 107° [Berichte, 20, 1215).

Propenyl Benzoic Acid, C^H^^^x tt'^' ', is obtained from oxyisopropyl

benzoic acid (p. 777). Boiling hydrochloric acid converts it (analogous to atropic
acid) into a polymeric acid.

3. Phenyl-angelic Acid, CjjHj^Oj = CjHj.CHiC^f ^^s h> '^''°'" benzaldehyde

and normal butyric acid, yields Phenyl-valeric Acid, CjH5.CH2.CH(C2H5).
CO2H, with sodium amalgam. It melts at 104°. The ortho-nitro product of this
is reduced to an ortho-amido-acid, which parts with water and yields the anhy-

^CHj.CH.CjHj
dride, ethyl-hydrocarbostyril, CijHjjNO = C5Hj/ | , which can

-NH.CO
be easily changed into /3-ethyl-quinoline, C9H5(C2H5)N (analogous to the for-
mation of quinoline from ortho-amido-hydrocinnamic acid, p. 758).

/-Cumenyl-Acrylic Acid, Ci^HuO^ = C3H,.C5H4.CH:CH.C02H (with iso-
propyl), may be obtained from cumic aldehyde and sodium acetate. It melts at
158°. Nitration produces /-nitrocinnamic acid and o-nitrocumenyl-acrylic acid
(melting at 156°). Cumin indigo (di-isopropyl indigo) can be obtained from the
latter (this is analogous to the rearrangement of o-nitro-cinnamic acid). o-Amido-
cumenyl-acrylic acid, obtained by reduction, condenses to cumostyril (isopropyl-,
carbostyril) (p. 812), and cumoquinoline. In addition to o-nitro-cumenyl-acrylic
acid, o-nitro^-propylcinnamic acid, C3Hj.C5H3(N02)CH:CH.C02H (with the
normal propyl group), is also formed by a molecular rearrangement. Its amido-
derivative is »-propylcarbostyrir(.ffi?r2V.4/«, 19, 255; 20, 2771).

We have an example of a doubly unsaturated acid in
Phenyl-propiolic Acid, C^Yi.f)^ = Ce^i.C\C.(ZO^Yi. (p. 244).
It is obtained by boiling a- and /J-brom-cinnaraic acids with alco-
holic potash, by acting upon sodium phenyl- acetylene, CeHj. C • CNa,
with carbon dioxide, and when the latter and sodiuiiQ act upon /S-
brom-styrolene. It is prepared by boiling the dibromide of ethyl
cinnamate (p. 809), with alcoholic potash (3 molecules). It crys-

AMIDO-PHENYL PROPIOLIC ACID. 815

tallizes from hot water or carbon disulphide in long, shining
needles, melting at 136-137° and subliming; under water it melts
at 80°. When heated to 100° with water it decomposes into carbon
dioxide and phenyl acetylene. It combines with 2 and 4Br, and
yields hydrocinnamic acid with sodium amalgam. Zinc dust and
glacial acetic acid, or sodium and methyl alcohol, convert it into
cinnamic acid. When its ethyl ester is dissolved in sulphuric acid
and diluted with water we get benzoyl acetic ester (p. 763).

Nitro-phenyl propiolic acids, C5H4(N02).C:C.COjH.

o-Nitro-phenyl Propiolic Acid is obtained when aqueous soda acts upon the
dibromide of o-nitro-cinnamic acid. An easier method consists in mixing the di-
bromide of the o-nitro-cinnamic acid ester (p. 811) with alcoholic potash (3 mole-
cules) [Anna/en, 212, 140). It occurs in commerce in the form of a 25 per cent,
paste. To purify this it is first converted into the ethyl ester. The acid crystal-
lizes from hot water or alcohol, in needles, or shining leaflets, and decomposes at
1 56°. When boiled with water it decomposes into carbon dioxide and o-nitro-
phenyl acetylene (p. 802). When boiled with alkalies it yields isatin : —

CeH,(^^^^°^"= CeH,/<J°\c.OH + CO,.

It dissolves in concentrated sulphuric acid, with conversion into the isomeric
isatogenic acid, which at once forms carbon dioxide and isatin.

^ digested with alkaline reducing agents (grape sugar and potas-
sium hydroxide, ferrous sulphate, hydrogen sulphide, potassium
xanthate) it readily changes to indigo blue (Baeyer, 1880) : —

2C,H,N04 + 2H, = Ci.HioN.O, + 2CO2 + 2H,0.

Therefore nitrophenyl propiolic acid may serve as a substitute for
natural indigo, especially in calico printing.

The ethyl ester of the acid is obtained by rapidly conducting hydrochloric acid gas
into the mixture of the acid and 10 parts absolute alcohol, until solution ensues.
It is very soluble in ether and separates in large crystals, melting at 60-61°. It
is saponified on heating a mixture of sulphuric acid, water and glacial acetic acid
(equal parts) to 100°. (p. 810) When it is dissolved in sulphuric acid it changes to
the isomeric isatogenic ester. Ammonium sulphide reduces it to the indoxylic
ester.

p-Nitrophenyl Propiolic Acid is formed from the/-nitro cinnamic ester, after the
same manner as the orfho-acid [Annalen M-2, 139, 150). It crystallizes from
hot alcohol in needles, and melts at 198° (181°) with decomposition. When
boiled with water it breaks up into carbon dioxide and /-nitrophenyl acetylene. It
yields /-nitroacetophenone (p. 728), if digested at 100° with sulphuric acid.

The ethyl ester crystallizes from alcohol in needles; melting at 126°. When
digested with sulphuric acid at 35° it forms /-nitrobenzoyl acetic acid (p. 763).

0 Amido-phenyl Propiolic Acid is obtained by reducing
nitrophenyl propiolic acid with ferrous sulphate and ammonia
{Berichte, 16, 679). It separates as a yellow, crystalline powder,

8l6 ORGANIC CHEMISTRY.

melting at 128-130°, with decomposition into carbon dioxide and
amidophenyl acetylene (p. 802). When boiled with water it yields
amido-acetophenone (p. 728).

y-Chlorcarbostyril results when the acid is boiled with hydrochloric acid, and
y-oxycarbostyril upon heating it with sulphuric acid. Here there occurs a closed,
ringed-shaped union of atoms {Berichte, 15, 2147) : — •

.C:C.CO,H -CChCH.

C,H / ■ + HCl = C^H / );C.OH + H,0.

T/-Chlorcarbostyril.

Sodium nitrite converts the hydrochloride into the diazo- chloride, which at 70°
yields cinnoline-oxy-carboxylic acid (see this).
Homologous Acids with two double unions : —
Cinnamenyl Acrylic Acid, CnHj^O^ = CjHj.CHiCH.CHiCH.CO^H, Cin-

namenyl Methacrylic Acid, CijHuOj = CjH^.CHiCH.CHrC^^^Q'lU, etc., have

been produced by the condensation of cinnamyl aldehyde with acetic acid, pro-
pionic acid, etc. (p. 8o5).

Ketonic Acids (p. 761).

Cinnamyl Formic Acid, CgHj.CHiCH.CO.COjH. This is the only unsat-
urated a-ketonic acid known. It is obtained, like benzoyl formic acid, from cin-
namic chloride, with potassium cyanide, etc. ; and by the condensation of ben-
zaldehyde and pyroracemic acid, CHg.CO.COjH, by means of hydrochloric acid
gas (p. 716). It is a gummy mass and is gradually decomposed into its compo-
nents by the alkalies, even in the cold.

The orikonilro derivative is similarly formed from o-nitrobenzaldehyde, melts
at 135°, and is changed by alkalies, even in the cold, with elimination of oxalic
acid, into indigo [BericAte, 15, 2863) : —

2CeH.(N0.).C.H„.C0.C02H + 2H2O =

(CeH^iC^ONH), + 2C,O^H, -f 2H,0.
Indigo.

Unsaturated ^-ketonic adds are produced by the condensation
of benzenes with maleic anhydride, etc., by means of AICI3 (see
benzoyl propionic acid) (just as phthalic anhydride condenses with
fatty acids and benzenes p. 787) : —

C,H, + C,H,(CO),0 = CeHs.CO.C.Hj.CO^H.

Benzoyl Acrylic Acid, CgH5.C0.CH:CH.CO2H, from benzene and maleic
anhydride, crystallizes with water in shining leaflets, melting at 64°, but at 97°
when anhydrous {Berichte, 15, 889). It yields benzoyl propionic acid by reduc-
tion (p. 764).

Benzoyl Crotonic Acid, CjHj.CO.CjH^.COjHjfrom benzene and citraconic
anhydride, melts at 113°. /TO PH

Benzal-Aceto-acetic Acid, C5H5.CH:C('pQ^3- Hs ethyl ester is formed

by the condensation of benzaldehyde and aceto acetic ester by means 'of HCl or
ZnClj. Sometimes it solidifies in crystalline form, and melts at 60°; it boils near
296°. It condenses with phenylhydrazine to diphenylmethylpyrazole, Benzalde-

AMIDO-PHENYL PROPIOLIC ACID. 817

hyde condenses with ethyl and diethyl aceto-acetic esters, acting at the time upon
the methyl group (Annalen, 218, i8i). /po rw

j8-Benzal-lsevulinlc Acid, CgHj.CHiC/^^-^^s jj, is produced by the con-
densation of benzaldehyde and Isevulinic acid in acid solution, and melts^at 125°.
It parts with water upon distillation and forms aceto a naphthol, C^^\CJii2(0U.).
(CO.CH3), just as a-naphthol is produced from phenyl-isocrotonic acid (p. 813).

When benzaldehyde and lEevuUnic acid condense in alkaline solution the pro-
duct is : —

d-Benzal-laevulinic Acid, C^lifiB.-.Cii.CO.C^'H^.CO^'H., melting at 120°
(Berichte, 23, Ref. 576).

Oxy-acids and coumarins.

The unsaturated oxy-acids, or phenol acids, containing hydroxyl
in the benzene nucleus can be obtained from the unsaturated amido-
acids (the amido-cinnamic acids) by boiling the diazo-derivatives
with water: —

C H /N^2 Yields C H /°"

Amido-cinnamic Acid. Oxy-cinnamic Acid.

They are synthetically prepared from the oxybenzaldehydes, CgHi
(OH).CHO, by heating them with the sodium salts of the fatty
acids (p. 806). The acidyl derivatives of the oxy-acids are first
produced : —

OH

/

* ^CHO

O.C,H,0

C^h/ +CH3.CO,Na + (C2H30),0 =

\CHO

C,h/ " " -f C^H^O, + H,0.

\CH:CH.C02Na

These yield the acids when saponified with alkalies. Those isome-
rides, belonging to the ortho-series, can here, by exit of water,
yield inner anhydrides (5-lactones), called coumarins : —

,OC,H,0 yO-

CfiHy ' ' =C6h/ ^CO -f C,H30.0H.

^CHiCHCO^H \cH:CH/

Aceto-(7-coumaric Acid. Coumarin.

Such coumarins are produced (i) by the condensation of phenols
and aceto-acetic esters when they are heated with sulphuric acid
(v. Pechmann, Berichie, i6, 2126): —

CH3 .0

C.H^.OH + CO/ =CeH,( )CO-j-C,H,.OH.

-CH,.CO,C,H, \qCH3):CH/

Resorcinol especially is very reactive, forming /3-methyl umbelliferon. Orcin

8l8 ORGANIC CHEMISTRY.

yields dimethyl umbelliferon, and pyrogallol yields methyl daphnetin, etc. {Be-
richte, 17, 2129, 2187). Citric acid {Berichie, 17, 931) reacts like aceto-acetic
ester. Resorcinol and phloroglucin also yield di- and tri-coumarins [Berichte, 20,

1329)-

2. The condensation of the phenols with malic acid when heated
with sulphuric acid or ZnCl, (it is very probable the malic acid
first yields malonic aldehyde, CHO.CHj.COjH) (v. Pechmann,
Berichte, 17, 929, 1646): —

.0-

CeH5{0H) + CHO.CHj.COjH = Cfi/ ^CO + 2H2O.

Coumarin.

Resorcinol yields umbelliferon (oxycoumarin, p. 821), while daphnetin is
obtained from pyrogallol (p. 823). Hydroquinone, orcin, phloroglucin and
/3-naphthol react similarly.

3. Dicoumarins are produced by the condensation of salicylic aldehyde and
succinic acid (p. 807) ; with pyrotartaric acid the product is coumarin propionic
acid (Berichte, 23, Ref. 97).

The coumarins correspond to the 5-lactones of the paraffin series,
derived from the 5-oxy-acids (p. 353). They are distinguished
from them by their much greater stability. Boiling water does not
affect them ; they dissolve unaltered in the alkalies (carbon dioxide
again separates them) and are converted into salts of the ^-oxy-
acids by protracted heating with concentrated alkalies. Similarly,
the oxy-acids are not converted into the corresponding coumarins
either by boiling with water, or by heating them. This change
only occurs upon distilling their aceto-compounds, or through the
action of hydrobromic acid {^Berichte, 18, Ref. 28).

(i) Oxycinnamic Acids, CeH^^' PH-PH CO H Coumaric Acids.

Meta-coumaric Acid (i, 3), from w-amido-cinnamic acid and from m-oxy-
benzaldehyde (p. 817), crystallizes from hot water in white prisms, and melts at
191°. Sodium amalgam converts it into hydro-»«-coumaric acid (p. 774).

Para-coumaric Acid (l, 4) is obtained from/ amido-cinnamic acid, and from
/-oxybenzaldehyde, also on boiling the extract of aloes with sulphuric acid.
Preparation, Berichte, 20, 2528. It crystallizes from hot water in needles, and
melts at 206°. Sodium amalgam converts it into hydropara-coumaric acid;
fused with KOH it yields /-oxybenzoic acid and acetic acid. It is identical with
naringinic acid bom the glucoside naringine (Berichte, 20, 296).

Ortho-coumaric Acid (i, 2) occurs in Melilotus officinalis,
together with (7-hydro-coumaric acid. Nitrous acid converts (7-amido-
cinnamic acid into coumaric acid ; its acetyl derivative is obtained
from salicylic aldehyde and sodium acetate. It is most readily
prepared by boiling coumarin for some time with concentrated

COUMARIN. 819

potassium hydroxide, or better, with sodium ethylate (^Berichte, 18,
Ref. 28; 23, 1714)-,.

Ortho-coumaric acid is very easily soluble in hot water and in
alcohol, and melts with decomposition at 208°. Sodium amalgam
converts it into melilotic acid, and fusion with potassium hydroxide
into salicylic and acetic acids. Its alkali salt solutions are yellow
colored and show a green fluorescence. Aceto-coumaric add (&tt
above) melts at 146°, and is split into acetic acid and coumarin on
the application of heat. The free couraaric acid heated alone does
not yield coumarin, but only when treated with acetic chloride or
anhydride.

In addition to the above ortho-coumaric acid (,8) we have also n-coumaric
acid or the so-called Coumarinic Acid, CgH^^„ „ p„ „, which is known

only in its salts and ethers, and when set free at once yields water, and its
anhydride — ^coumarin. Its relations to common coumaric acid are perfectly simi-
lar to those of male'ic to fumaric acid; the latter, according to Wislicenus, is
axially-symmetric, whereas coumarinic acid, only known in its anhydride, \^ plane-
symmetric : — -

HO.C5H4.CH CH.CjH-.OH

II II

CH.CO2H CH.CO2H

Ordinary Coumaric Acid. Coumarinic Acid.

These assumptions do not accord with the behavior of nitrocoumaric ester, which
rather points to the idea of Michael, that coumarinic acid is a dioxylactone
{Berichte, 22, 1714). The basic salts of the acid, e.g., Cg\i^{0T^3.).C^\i^.C0.^1'is.,
are obtained on boiling coumarin with dilute alkalies, and diifer from the salts of
ordinary coumaric acid, which are prepared by strongly heating coumarin with
alkalies (see above). From the former acids precipitate coumarin, from the latter,
coumaric acid. If coumarin be boiled with caustic potash (2 molecules) and
methyl iodide (2 molecules), in alcoholic solution, we obtain a dimethyl ether,
which, on saponification, yields Methylcoumarinic Acid, C5H^(O.CH3).C2H2.
COjH, melting at 90°; greater heat (150°) produces a dimethyl ether which when
saponified, yields Methylcoumaric Acid, melting at 182°. The latter acid is
more readily obtained by boiling coumaric acid with caustic potash (i molecule),
methyl iodide and alcohol. It is, moreover, directly prepared from methyl sali-
cylic aldehyde, C5H^(O.CH3).CHO (p. 817), by means of sodium acetate, etc.
Strong heat, boiling with hydrochloric acid and even sunlight, converts methyl
coumarinic acid into stable methyl coumaric acid. Sodium amalgam converts both
acids into methyl-melilotic acid; and also yields the same addition product with
bromine. Potassium permanganate oxidizes both to methyl salicylic acid. Ethyl
coumarinic and Ethyl coumaric Acid, Cgll^(0.C.i^Yi^).C.^'H.2-^0^^, manifest
the same deportment; the former melting at 102°, the latter at 132° (Annalen,
216, 139).

Coumarin, QHeOj = CgHj^'^ j^~^CO, the ^-lactone of

coumarinic acid, occurs in Asperula odorata, in the Tonka beans
(from Dipterix odorata), and in Melilotus officinalis. It is artifici-
ally prepared by heating salicylic aldehyde with sodium acetate and

820 ORGANIC CHEMISTRY.

acetic anhydride. At first we get aceto-coumaric acid, which de-
composes further into acetic acid and coumarin (p. 8i8). It is
soluble in hot water, readily in alcohol and ether, crystallizes in
shining prisms, possesses the odor of the Asperula, melts at 67°,
and distils at 290°. When warmed it dissolves in alkalies with a
yellow color; on boiling coumarinic and coumaric acids result
(see above). Potassium permanganate destroys it (like the homo-
logous phenols). Sodium amalgam changes it to melilotic acid
(P- 774)-

Bromine converts it into a dibromide, CgHsBr^O^, melting at 105°. Coumari-
lie acid is produced when coumarin dibromide or brom-coumarin is boiled with
alcoholic potash (p. 825).

o-Nitro-coumarin, C9H5(N02)02, from » nitrosalicylic aldehyde, melts at
191°, and cannot be directly rearranged into carbostyril {Berichte, 22, 1705).
o-Nitro-carbostyril is produced by heating the amide of o-nitro coumarinic acid with
hydrochloric acid.

When salicylic aldehyde acts upon the higher fatty acids we derive homologous
alkyl coumarins (p. 807) Propionyl-coumarin, Cj ^HjOj, amethyl coumarin,
from propionic acid, melts at 90°, and boils at 292°. ^-Methyl coumarin (p. 818),
from phenol and acetoacetic ester, melts at 125°. Butyryl-Coumarin, CnHuO,,
a-ethyl coumarin, from butyric acid, and salicylaldehyde melts at 71°, and boils at
299°.

The alkyl-ether acids, ^ ^^ ^(^%^^_co ^yL, ^eH^XCHrCfcH,).^^ H,etc.,
Methyloxyphenyl Acrylic Methyloxyphenyl Crotonic
Acid. Acid.

derived from the alkyl-oxy-benzaldehydes (methyl salicylic aldehyde, methyl
anisaldehyde), yield esters of unsaturated phenols (just as styrolene arises from
cinnamic acid) by the action of hydrochloric acid and a soda solution, when carbon
dioxide is eliminated, c. g, : —

r H /'^■^^t and C H /OCH3

^6"4\CH:CH2 ^""^ ^«"i\CH:CH.CH3, etc.

Vinylanisol. Propenylanisol.

The latter is the anethol (p. 803) found in anise oil.

Dioxyacids.

The dioxyphenyl acrylic acids are caffeic acid and its methyl esters : ferulic and
isoferulic acids, and umbellic acid, whose anhydride is umbelliferon. The first
acids are intimately related to protocatechuic acid and its ethers, and to vanillic
and iso-vanillic acids, since they have the side groups in the same position
(p. 780) :-

■6^3 -j

CHiCH.CO^H (i)

OH (3) CeH,

OH (4)

CaffeTc Acid.

r CH:CH.CO,H

f CH:CH.COjH

\ O.CH3

C6H3J0H

lOH

I0.CH3

Ferulic Acid.

Isoferulic Acid.

In umbellic acid the side-chains occupy the same position as in /3-resorcylic
acid (p. 778) ; one hydroxyl group is in the ortho-place referred to the side-chain

COUMARIN. 821

containing carbon, hence the acid can yield an inner anhydride (umbelliferon),
just as o-coumaric acid forms coumarin : —

fCH:CH.C02H (i) fC^H^.CO

iOH (4) (.OH

Umbellic Acid. Umbelliferon.

Caffeic Acid, CgHgOj, is obtained when the tannin of coffee (p. 785) is boiled
with potassium hydroxide. It is prepared artificially from protocatechuic aldehyde
if the latter be heated with acetic anhydride and sodium acetate, and then the
resulting diacetate saponified. It crystallizes in yellow prisms, and is very readily
soluble in hot water and alcohol. The aqueous solution reduces silver solutions
upon application of heat, but not alkaline cupric solutions. Ferric chloride causes
a green coloration, which becomes dark red by the addition of soda. When fused
with potassium hydroxide, caffeic acid decomposes into protocatechuic acid and
acetic acid. Pyrocatechin results when it is exposed to dry distillation. Sodium
amalgam converts it into hydrocaffeic acid (p. 782).

Ferulic Acid, CjqHjjO^, is the methyl-phenol ether of caffeic acid and corre-
sponds to vanillin. It is found in asafoetida, from which it may be obtained by
precipitation with lead acetate and by the subsequent decomposition of the lead
salt with sulphuric acid. It has been synthetically prepared from vanillin when
heated with sodium acetate, etc. ; also from »2-methoxy-cinnamic ester (from
wz-nitrobenzaldehyde) [^Berichle, 18, Ref. 682). It is very soluble in hot water,
crystallizes in shining needles or prisms, and melts at 169°. Ferric chloride im-
parts a yellowish-brown coloration to its aqueous solution. When fused with
potassium hydroxide, it forms protocatechuic acid and acetic acid. Potassium
permanganate oxidizes the acetate to aceto-vanillin. Ferulaldehyde, the aldehyde
of ferulic acid, has been obtained from glycovanillin IJBerichte, 18, 3482).

Isoferulic Acid, Hesperetinic Acid, CjqHjjOj (see above), was first obtained
from the glucoside hesperidine, and is prepared by partially methylating caffeic
acid (together with a little ferulic acid). It melts at 228°, and if fused with potas-
.sium hydroxide decomposes into protocatechuic acid and acetic acid. The oxida-
tion of its acetate produces isovanillic acid; sodium amalgam yields isohydro-
ferulic acid (p. 782).

By the introduction of more methyl into ferulic and isoferulic acids, as well as
caffeic acid, there results dimethyl caffeic acid, C8H3(O.CH3)2.C2H2.C02H,
melting at l8l°; this is oxidized by potassium permanganate to dimethyl proto-
catechuic acid. Methylene Caffeic Acid, CjHjf „^CH2).C2H2.C02H, is ob-
tained synthetically from piperonal (p. 726) by means of sodium acetate, etc.

Umbellic Acid, CgHgOj = C6H3(OH)2.C2H2.C02H (see above), is ob-
tained by digesting umbelliferon with caustic potash, and then precipitating with
acids. It is a yellow powder, decomposing about 240°. Its anhydride, corre-
sponding to coumarin, is —

Umbelliferon, C9H5O3, Oxycoumarin. It is found in the bark of Daphne
mezereum, and is obtained by distilling different resins, such as galbanum and
asafoetida. It is obtained synthetically from /3-resorcyl aldehyde, CgH3(OH)2.
CHO, by means of sodium acetate, etc. ; and also by the condensation of resor-
cinol with malic acid (p. 8 1 8). It consists of fine needles, sparingly soluble in
hot water and ether, melts at 224°, and sublimes undecomposed. When heated
it has an odor resembling that of coumarin. It dissolves with a beautiful blue
fluorescence, in concentrated sulphuric acid. It dissolves in cold alkaline hydrox-
ides unaltered, but when heated umbellic acid is produced. Sodium amalgam
converts it into hydro-umbellic acid (p. 782). Fusion with caustic alkali affords
/3-resorcylic acid and resorcinol.

82 2 ORGANIC CHEMISTRY.

When umbelliferon is treated with methyl iodide and caustic alkali it conducts
itself like coumarin (p. 819). The products of the reaction are a-Dimethyl-
umbellic Acid, and the more stable /3-Dimethyl-umbellic Acid, CjHj
(O.CH3)j.C2H2.C02H; these correspond to methyl coumarinic and methyl
coumaric zx\6s {Berichte, 16, 2115; 19, 1777). Oxycoumarilic acid is formed
in like manner from the dibromide by the action of alcoholic potash.

The so-called ^-Methyl-umbelliferon, C„H3(0H), rtru^^yCiiy^^' ^^^
been prepared synthetically by the condensation of resorcinol with aceto acetic
esters (p. 818). It melts at 185°, and when fijsed with caustic potash yields
resacetophenone, CgH3(OH)2.CO.CH3 (p. 729) and resorcinol {Berichte, 16,
2120). The introduction of methyl produces dimethyl ^8- methyl umbellic acid,
CgH3(O.CH3)2.C(CH3):CH.C02H, which potassium permanganate oxidizes to
dimethyl-^-resorcyiic acid (p. 778).

As a representative of the doubly unsaturated dioxyacid class we may mention
Piperic Acid, C^^^f>^ = C3H3 (^q^CHj).CH:CH.CH:CH.C02H. Its side-
chains are arranged like those in protocatechuic acid. Its potassium salt is pro-
duced when the alkaloid piperine is boiled with alcoholic potassium hydroxide.
It consists of shining prisms. The free acid is almost insoluble in water, and crys-
tallizes from alcohol in long needles, melting at 217°. Its salts with i equivalent
of base are very sparingly soluble. It combines with four atoms of bromine. It
is oxidized to piperonal when digested with potassium permanganate ; at 0° the
side-chain is eliminated as racemic acid (Berichte, 23, 2372). When fused with
potassium hydroxide it breaks clown into acetic, oxalic and protocatechuic acids.
Chromic acid destroys it completely. Sodium amalgam converts it into two iso-
meric hydropiperic acids, Ci2Hi20^, a and /?. The a-acid melts at 78°, and
when digested with sodium hydroxide is converted into the /5-acid, melting at
131°. The a-acid yields a dibromide with bromine; the ;8-acid when acted upon
with sodium amalgam passes into the so-called piperhydronic acid, CjjHj^Oi,
melting at 96°.

^sculeiin and Daphnetin are anhydrides ((5-lactones) of unsaturated trioxy-
acids, and may also be designated dioxy-coumarins : —

/CH:CH.CO (1) /CH:CH.CO (i)

C3H,— 0_ " (2 C,H,— 0._- {2)

\(0H)2 (4,5) \(OH)2 (3,4).

^sculetin. Daphnetin.

The three hydroxyls in jesculetin have the same position as in oxyhydroquinone,
CjHg(0H)3 (1,3, 4), and in daphnetin they are in the same relation as in pyro-
gallol. Their corresponding acids are only known as tri-ethyl-ether acids : —

P „ /CHiCH.COjH (I) /CH:CH.CO,H (i)

^s"^\(O.C2H,)3 (2,4,S) ^«"^\(0.C2H,,)s (2,3,4).

Triethyl-aBsculetinic acid. Triethyl Daplinetic acid.

^sculetin, CjHgO^, is present in the bark of the horse chestnut, partly free
and partly as the glucoside asculin, from which it is prepared by decomposition
with acids or ferments. It crystallizes with a molecule of water in fine needles or

PHTHALYL ACETIC ACID. 823

leaflets, and dissolves with a yellow color in the alkalies. It reduces silver and
alkaline copper solutions and receives a green color from ferric chloride.

Ethyl iodide and caustic alkali convert it (analogous to the deportment of um-
belliferon and coumarin) into two isomeric triethyl-sesculetinic acids (see
above), which are oxidized by MnO^K into a triethoxybemoic acid, CgHj
(O.C2H5)3.C02H, which parts with carbon dioxide and becomes triethoxyhydro-
quinone, CgH3(O.C2H5)3 {Berickte, 20, 1119).

Daptanetin, C9H5O4 (see above), is obtained by the decomposition of the glu-
coside daphntn. It is prepared synthetically by the condensation of pyrogallol
with malic acid through the action of sulphuric acid (p. 818). It crystallizes in
yellow needles or prisms, melting at 255°. It reduces silver and alkaline copper
solutions, even in the cold, and receives a green color from ferric chloride. Ethyl
iodide and caustic alkali convert it into triethyl daphnetic acid, C5H3
(O.C2H5)3.C2H2.C02H, from which we obtain Triethyl-pyrogallol-carboxylic
Acid (p. 782) — Berichte, 17, 1089 — by means of potassium permanganate.

Unsaturated dibasic acids. Under this head may be classed
(i) Benzal-malonic Acid, C5H5.CH;C(C02H)2. This is produced in the
condensation of benzaldehyde and malonic acid on digesting with glacial acetic acid
(p. 7 '6). It crystallizes from hot water in shining prisms, melting at 196°, with
decomposition into carbon dioxide, and cinnamic acid. When- it is boiled with
water it splits into benzaldehyde and malonic acid ; its salts, however, are stable.
Sodium amalgam converts it into benzyl-malonic acid (p. 791). Its diethyl ester,
C5H5.CH:C(C02. 02115)2, is derived from benzaldehyde and malonic ester by
means of HCl or ZnCl2. " It boils with slight decomposition about 310° (Anna-
len, 218, 121).

The three nitrobenzalmalonic acids, C5H^(N02).CH:C(C02H)2, have been
prepared by the condensation of the nitrobenzaldehydes with malonic acid. The
ortho-acid yields ;3-carbostyril carboxylic acid (Berichte, 21, Ref. 253) upon re-
duction with ferrous sulphate.

(2) Phenyl-malelc Acid, CgH5.C2H(C02H)2, from phenylmalic acid
(p. 792), forms very soluble prisms. It passes into its anhydride at temperatures
below 100°. The anhydride melts at 119° (Berichte, 23, Ref. 573).

(3) Cinnamyl Carboxylic Acids, C6'^4\ crfcH CO H '^^^ ortho-zxixi.
(i, 2), is produced when phthalidacetic acid is digested with alkalies and by
carefully oxidizing /3-naphthol with potassium permanganate (Berichte, 22, Ref.
654). More energetic oxidation produces carbophenyl glyoxylic acid (p. 765).
It melts at 174°, and reverts again to phthalidacetic acid.

The/flra-acid is obtained from terephthal-aldehydic acid and sodium acetate.
It is an insoluble, infusible powder. Nitration converts it into an ortho-nitro acid,
which yields indigo-dicarboxylic acid (this is analogous to o-nitro-cinnamic acid)
(Berichte, 19, 948).

The following are anhydrides (lactones) of oxydicarboxylic acids : —

. C = CH.CO,H
/ \r

formed by condensation of phthalic anhydride with sodium acetate (analogous to
the reaction of Parkin) (p. 806) (Berichte, 17, 2521) : —

(i) Phthalyl Acetic Acid, CioHgO^ = Cs^iv ^O

^rn\ / ^ ^ CH.CO2H

C6H.(co)o + CH3.CO2H = c,H /^^po + H2O.

824 ORGANIC CHEMISTRY.

It is insoluble in water, soluble with difficulty in alcohol, and melts with decom-
position about 243°. Salts of benzoylaceto-carboxylic acid (p. 765) are obtained
by dissolving it in alkalies. When it is heated with water to 200° it breaks down
into carbon dioxide and aceto-phenone-carboxylic acid (p. 764). When heated

. C = CH.COjH
with ammonia it forms Phthalimide Acetic Acid, ^^^C ^NH

(p. 787); the ethylamines react analogously {Berichte, 19, 2368). Phthalyl-
acetic acid decomposes by distillation into carbon dioxide and methylene phthalide,

- C ^ :^ CHj

Cglij ^ pO . This derivative has an odor strongly resembling that of

phthalide. It forms vitreous rhombs, melting at 58-60° {Berichte, 17, 2522).

Fhthalic anhydride forms similar compounds with propionic acid, succinic acid,
etc. {Berichte, 14, 919).'

C . == CH.CH = , C .

Ethirne diphthalyl, CgH.^ ^O O^^ ^C.H^ [Berichte, 17,

C ^ ^ CH.CHg
2lio'),zxA Ethidene phthalide, C^/C yO , very similar to methy-

lene phthalide {Berichte, ig, 838), result upon condensation with succinic acid.

Phthalic anhydride and phenylacetic acid, CgHj.CHj.COjH, condense to
Benzylidene Phthalide {Berichte, 18, 3470), which can be transposed into
isomeric Isobenzal-phthalide {Berichte, 20, 2363) : —

/ C ^ ^6^5 /CH = C.C5H5

• C^H / )0 yields CeH^( /

Benzylidene Phthalide. Isobenzalphthalide.

Ammonia converts the latter into hohenzal-phthalimidine, that can be changed to
Phenyl-isoquinoline {Berichte, 18, 3478; ig, 830) :'

-CH = CC^Hs ,CH = C.C.Hj

C^H / I and CeH / |

\C0 — NH \CH = N

Isobenzal-phthalamidine. Phenyl-isoquinoline.

.0 CO

(2) Coumarin-Carboxylic Acid, CgH^^^ | , is produced by

~-CH = C.COjH
condensing salicylic aldehyde and malonic acid upon heating them with glacial
acetic acid. It melts at 187°, and about 290° breaks down into carbon dioxide
and coumarin {Berichte, ig, Ref. 350).

Derivatives of Benzene containing closed Side-chains.

The parent substances of the compounds included in this series
are benzene furfurane {coumarone'), benzothiophene {thionafhthene),
and benzopyrrol (indol) : —

y^^<^ /CII^ .CH^^

c,H / Jen c,H / ^CH c,H / Jen
^ o / \ s ^ \nii/

Coumarone. Benzothiophene. Indol.

BENZOFURFURANE OR COUMARONE GROUP. 825

They contain, in addition to the benzene nucleus, a closed chain
of five members (as in furfurane, thiophene and pyrrol, p. 521);
two of the C-atoms belong to the benzene nucleus.

I. BENZOFURFURANE or COUMARONE GROUP.

The coumarone compounds are produced : —
(i) By the action of alcoholic potash upon coumarin dibroraides
or a-brom-coumarins (Fittig, Annalen, 126, 170) : —

.CH:CBr ,CH.

C^H / I + H,0 = C,H / ^C.CO.H + HBr.

\— O .CO ^ O /

Other coumarins react similarly. Thus, umbelliferon yields oxycoumarilic acid
[Berichle, ig, 1783), and sesculetin and daphnetin give dioxycoumarilic acids
{Berichte, 17, 1075). The coumarones are produced by the elimination of the
carboxyl group from the coumarilic acids.

(2) By the action of chloraceto-acetic esters upon the sodium salts
of the phenols; /J-methyl coumarilic esters result (Hantzsch, Be-
richte, ig, 1291 ; 1298): —

.CH3
CO.CH3 .C^

C-Hs.O.Na + I = C.H / ^C.COjR + NaCl + \\0.

CHC1.C0„R ^O^

^-Methyl Coumarilic Ester.

Thus, dimethyl coumarilic acid is derived in this way from para-cresol, and the
two naphthols yield two naphthofurfuranes t^Berichte, ig, 1301). Resorcin and
hydroquinone afford benzo-difurfurane, and pyrogallol a benzo-trifurfurane deriva-
tive {Berichte, ig, 2930; 20, 1332).

(3) By heating o-aldehydo-phenoxy-acetic acid (from salicylaldehyde and chlor-
acetic acid) with sodium acetate (Berichte, 17, 3000) : —

CeH.<g'^^^.CO,H = C^H.<'J^'')CH + CO, + H,0.

Coumarone.

/^^^

Coumarone, CoH.O = CgH^^' /CH, is formed by distilling coumarilic

acid with lime. It is present in coal tar {Berichte, 23, 78). It is an oil that sinks
in water, and boils at i6g°. Concentrated acids convert it into a resin. With bro-
mine it yields a dibromide, melting at 88°.

/C(CH3)

/3-Methyl Coumarone, CjHgO = C^H^/ ">CH, from /3-methyl cou-

marilic acid, is an oil, boiling at 189°. Dimethyl coumarone, CgH3(CH3)

.C(CH3)
( /CH, from dimethyl coumarilic acid, boils at 210°.

^— O — / .

69

826 ORGANIC CHEMISTRY.

CH
a-Coumarilic Acid, C3H5O3 = C^H^/ "^C.COaH, a-coumarone car-

boxylic acid, is obtained from couraarin dibromide or a-brora coumarin. It crys-
tallizes from hot water in delicate needles, melting at 190° and distils at 310°. It
breaks down into salicylic and acetic acids, when fused with caustic potash. It
does not combine with bromine or hydrobromic acid. Sodium amalgam converts
it into hydrocoumarilic a«V, CgHjOj, melting at 1 16°, and distilling, with de-
composition, at 300°.

^-Methyl Courriarilic Acid, C9H5(CH3)03. Its ethyl ester is produced on
heating sodium phenoxide with aceto-acetic ester (see above). It melts at 51°,
and boils at 290°. The free acid crystallizes firom hot water in needles, melting at
189°, and then subliming. If it be rapidly heated it decomposes into carbon di-
oxide and 3-methyl coumarone.

/C.(CH3)

Dimethyl Coumarilic Acid, CeH3(CH3)( /C.COaHjhasbeenpre-

O — ^
pared from sodium para-cresol with chlor-acet-acetic ester, and from dimethyl cou-
marin bromide. It melts at 224°, and at higher temperatures decoi.poses into
carbon dioxide and dimethyl coumarone.

2. BENZO-THIOPHENE GROUP.

Benzo-thiophene, C^/ /CH, bears the same relation to thiophene as

benzofurfurane to furfurane (p. 824). It also bears the same relation to naphtha-
lene that thiophene bears to benzene (the group CH=CH of a benzene nucleus
is replaced by a sulphur atom in it), hence it is also known as Thionaphthene.

The only known derivative of this series is a-Oxybenzothiophene, or Oxy-
thionaphthene, C5H3(OH)(C2H2S), corresponding to o-naphthol. It is pro-
duced by the condensation of thiophenaldehyde and succinic acid (Berichte, 19,
1618). It sublimes in long needles, and melts at 72°. It resembles a-naphthol in
its reactions.

3. BENZOPYRROL OR INDOL GROUP.

This embraces a series of bodies which can be regarded as deriva-
tives of the simplest of them all — of indol, CgH,N. They were
first derived from indigo-blue, and bear an intimate relation to the
latter. The most important members are : —

^ H /CH\cH c H /C(OH)\pj^

Indol. Indoxyl.

Oxindol. Dioxii^dol. Isatin.

INDOL. 827

The last three bodies, so far as concerns their synthetic methods
of formation, are amido-anhydrides of ortho-amido-acids of ben-
zene (p. 755). Oxindol is the lactam of (9-amido-phenyl-acetic
acid (p. 75s), dioxindol the lactam of ^-amido-mandelic acid (p.
772), while isatin represents the lactirae of i?-amido-benzoyl-formic
acid (p. 762). On the other hand, these three bodies can be con-
verted into each other, and have been obtained from isatin. By
complete reduction they may be transformed into indol. All indol-
derivatives contain a closed chain, comprising four carbon atoms
(two of which belong to the benzene nucleus) and one nitrogen
atom (p. 824) analogous to that in pyrrol, hence, indol may be
called benzene-pyrrol. In accord with this indol and especially the
more stable methyl indols exhibit the reactions of pyrrol {Berichte,
19, 2988, 3028). By the rupture of the pyrrol ring (in oxidations,
etc.), the indol Compounds are changed to ortho-amido-acids of
benzene.

Our knowledge of the indol derivatives and their kinship to
indigo rests mainly upon the researches of Baeyer {Berichte, 13,
2254, 16, 2188).

Indol, CsHjN, was first obtained in the distillation of oxindol,
and is a product of the reduction of indigo-blue with zinc dust. It
is also produced by heating (?-nitro-cinnamic acid with caustic pot-
ash and iron filings. From a theoretical standpoint, the following
methods of formation are especially interesting : the reduction of
(?-nitrophenyl-acetaldehyde (p. 721) with zinc dust and ammonia,
and the action of sodium alcoholate upon (?-amido-chlorstyrolene
(p. 802) :—

C«H4<NH™ = C6H,(S^)CH -f HCl.

This method represents indol as the anhydride of <7-amidophenyl-
vinyl alcohol, QH,(NH,)CH:CH(OH).

Indol may be obtained by various other methods; thus, by conducting the
vapors of the mono- and di-alkyl anilines and ortho-toludines through a tube
heated to redness {Berichte, 10, 1262); by distilling nitro-propenylbenzoic acid
(p. 814) with lime, or phenyl glycocoU with calcium formate; and in the pancreatic
fermentation of albuminates, or (together with skatole) in the fusion of the latter
with potassium hydroxide, but is best obtained by the first procedure {Berichte, 8,
336). A more convenient procedure is to distil o-indol-carboxylic acid (skatole)
with lime {Berichte, 22, 1976). Another noteworthy formation is that from the
quinoline derivatives, e.g., the fusion of carbostyril with potassium hydroxide, or
when tetrahydro-quinoline is conducted through a red-hot tube.

Indol crystallizes from water in shining leaflets, melting at 52"
and boiling about 245° with partial decomposition. It is readily
volatilized in aqueous vapor. Its vapor density (under diminished
pressure) corresponds to the formula CgHiN. It possesses a pecu-

828 ORGANIC CHEMISTRY.

liar odor, resembling that of naphthylamine. A pine splinter moist-
ened with hydrochloric acid and dipped into its alcoholic solution
acquires a cherry-red color. Indol possesses but very feeble basic
properties (similar to pyrrol), and is scarcely dissolved by dilute hy-
drochloric acid. Hot acids resinify it very readily.

On adding sodium nitrite to a solution of indol in acetic acid (90^) the latter
assumes a deep red color owing to the formation of Nitroso-indol, CgHgN(NO)
yellow crystals, melting at 172° {Berichte, 23, 2299).

ji-Aceto-indol, n^-Diaceto-indol (^Berichte, 22, 1977), and n-Aceto-indol [Be-
richte, 23, 1359, 2296) are all produced upon heating indol (and n-indol-carboxylic
acid) to 180° with acetic anhydride.

Alkyl Indols.

These are derived by replacing the hydrogen of indol by alkyls. Their isomer-
ides can be readily deduced from the following scheme : —

H

HC C— CH 3

HC C CH

H

/V

^ N I N

H n

It corresponds to that given to pyrrol. The benzene hydrogen atoms are
marked by the numbers I to 4. The substitution products derived from the
pyrrol nucleus can exist in three isomeric forms; they are designated, as with the
pyrrol derivatives, «-, u,- and /3 : —

.CH:CH ^CH.-C.CHg .C(CH3):CH

C.-a.i / C,H / / C,H / ^^

^ N.CH3 \nh ^nh

«-MethyI Indol. o-Methyl Indol. /3-Methyl Indol.

E. Fischer terms the derivatives of the pyrrol nucleus Py-{l, 2, 3)-derivatives,
those of the benzene nucleus B-(l, 2, 3, 4) -derivatives [Annalen, 236, 121 ;
Berichte, ig, Ref. 829).

The alkyl indols may be synthesized : —

(1) By the production of closed rings from o-amido-compounds (p. 827) :
»-amidobenzylmethyl ketone forms a-methyl indol (p. 729); «-amidochlorstyro-

lene, C^H^^ NH CH ' y'^^"^^ «-methyl indol; while a-phenyl indol is obtained

from o-nitrodesoxybenzoin, C5H4<^^^2-CO.C5Hg

\JNU2

(2) By heating the anilines with compounds, containing the group — CO.CHCI.
For example, aniline and chloraldehyde form indol ; with chloracetone, CH3.CO.
CHjCl, the product is a-methyl indol, and with /S-bromlsevulinic acid, CH3.CO.
CHBr.CHj.COpH, a^S-dimethyl indol is the product. The alkyl anilines and
toluidines [Berichte, 21, 3360) react in a similar manner.

The reaction does not always pursue the same course ; thus, aniline and brom-
acetophenone, heated together, yield a-phenyl indol and not the /3-product. This
is very probably due to the fact that the first product is C5H5.C(N.CgH5).CH2Br

INDOL. 829

{Berichte, 21, 1076). Similarly, »-methyl-a-plienyl indol is formed from brom-
acetophenone [Berichte, 21, 2595).

(3) Upon heating together phenylglycocolls and calcium formate. In this way,
phenylglycocoll, CgHj.NH.CHj.COjH, yields indol and tolyl glycocoU, toluindol
{Berichte, 23, Ref. 654) : —

CHs.CeH^.NH.CHj.CO^II + CHO.OH =

CHj.CeHj/^HXcH + CO3 + 2H,0.

4. A noteworthy and excellent method for the production of the alkyl indols
consists in condensing the phenylhydrazones of the aldehydes, ketones and ketonic
acids (p. 656) by heating them with hydrochloric acid or zinc chloride (E. Fischer,
Berichte, 19, 1563; 22, Ref. 14). The compounds of ;3-methyl-phenylhydrazine
behave similarly (p. 657). Thus, propylidene phenylhydrazone yields ;8-methyl
indol:- ^^^^

CeHj.NH.NiCH.CH^.CHj = C^H^/'-^'^CH + NH3.

NH

Propylidene-phenyl-hydrazone. )S-Methyl Indol.

Phenylacetaldehyde, CgHj.CHj.CHO, in like manner yields /3-phenyl indol.
a-Methyl indol is prepared from acetone-phenylhydrazone : —

C,H,NH.N:C/^g3 _ c,H,/^^Jc.CH3 + NH3.

Acetone-phenyl-hydrazone. a-Methyl Indol.

«a- Dimethyl indol is derived from acetone-methyl-phenyl-hydrazone : — -

vCHg ,CIi--^^::::::::^C.CHj

C,H5.N(CH3)N:C( = C,H / / + NH3.

^CHj ^N(CH3)

«a-Diniethyl Indol.

The first products from phenylhydrazine and the a- and y-ketonic acids (better
their esters) are the indol carboxylic acids (and their esters) ; these lose carbon
dioxide and pass into indols : —

C,H,.NH.N:C/^^3^^^^ _ C^-a/^^CZO^.C^H, + NH3.

Phenylhydrazone-pyroracemic Ester. o-Indol-carboxylic Ester.

The ;3-alkylhydrazine derivatives react very easily with pyroracemic acid,
upon warming them with dilute hydrochloric acid, sulphuric or phosphoric acid ;
the products are n alkyl-indol-carboxylic acids. When the phenylhydrazine de-
rivatives of the /3-ketonic acids, e. g., aceto-acetic ester, are heated with zinc
chloride they are principally converted into pyrazole compounds (p. 656). On
the other hand, compounds of acetoacetic ester and j3-alkylhydrazines (which
cannot form pyrazole compounds) yield indol derivatives with zinc chloride : —

.CH2.CO2.C2H5 /c/'^^z-^2^^

CeH..N(CH3).N:C(^^^ = C.H.^-^C.CH, + NH3.

Methylphenyl-hydrazone- N — CH3

Acetoacetic Ester. >ia-Dimethyl Indol

Carboxylic Ester.

830 ORGANIC CHEMISTRY.

See Annalen, 239, 223 for the indols from tolyl and naphthyl hydrazones.

Nearly all the alkyl indols possess the feecal odor of indol. The odor of the
»-methyl indols is similar to that of methyl aniline. The phenyl indols and indol
carboxylic acids are non-volatile and odorless. They are more stable toward acids
than indol, dissolve in concentrated hydrochloric acid, and are reprecipitated unal-
tered by water. Picric acid unites with all of them, forming compounds, crystalliz-
ing in red needles (distinction from the pyrrols, Berichte, 21, 3299). Most of the
indol derivatives give the pine-shaving reaction, the exceptions being the indol
carboxylic acids and the (z/3-dialkyl indols {Berichte, 21, 3300). It is only the
/?-alkyl- and aj3-dialkylindols that yield simple nitrosocompounds with nitrous acid
{Berichte, 23, 2299).

The methyl indols, like pyrrol, combine with aldehydes, acid anhydrides and
diazo-compounds (^«/-8V^/?, 20, Ref. 429; 21, Ref. 18). ^if(/ dye-stuffs, resem-
bling fuchsine and called rosindols {Berichte, 20, 815), are produced by heating
n-, a- and |8-methyl indol with benzene chloride and zinc chloride.

Interesting transformations are those of methyl indols and indol into quinoline
derivatives (similar to formation of pyridine compounds from pyrrol, p. 541). In
this change a methylene group pushes itself into the pyrrol ring, and the resulting
pyridine ring is then further methylated. The conversion ensues upon heating the
compounds with chloroform and sodium alcoholate {Berichte, 21, 1940), or with
alkyl iodides {Berichte, 20, 2199). In this manner a- and jS-methyl indol as
well as indol together with methyl iodide at 130° yield trimethyl-dihydroquino-
line : —

C8H5N(CH3) + 3CH3I = CsH,N(CH3)3 + 3HI {Berichte, 23, 2629 ; 22, 1979).

«-Acetyl- and /3-acetyl-(r-methyl indol are produced upon boiling a-methyl
indol with acetic anhydride, while_ a-acetyl-/3-methyl indol is obtained by like
treatment from /3-methyl indol. Boiling hydrochloric acid causes the elimination
of the acetyl groups {Berichte, 21, 1936).

K-Methyl Indol, CgH5N(CH3), may be obtained by heating «-methyl-indol
carboxylic acid to 200°. It is an oil, boiling at 239°. «-Ethyl Indol, C5H5N.
C2H5 (boiling at 247°), Is prepared the same as the preceding compound. Sodium
hypobroraite oxidizes both compounds, forming methyl and ethyl pseudo-isatin.
K-Phenyl Indol, CjH5N(C5H5), from K-phenyl-indol-carboxylic acid, is aheavy
oil. It imparts an intense, bluish-violet color to a pine shaving {Berichte, 17, 568).

a-Methyl Indol, CjH5(CH3)NH, Methyl Ketol, arises in the anhydride-
formation of o-amido-benzyl-methyl ketone (p. 729), and is very easily prepared
by heating acetone phenylhydrazone with zinc chloride to 180° (see above). It
crystallizes from ligroine in colorless needles or leaflets, melting at 59°. Its odor
is like that of indol, and its reactions are similar. Oxidation with MnO^K (by
rupture of the pyrrol ring at the point of the double binding) converts it into
aceto-»-amido-benzoic acid (p. 749). a-Indol carboxylic acid is formed when it is
fused with caustic potash.

a-Phenyl Indol, CjH5(C5H5)NH, maybe formed from acetophenone phenyl-
hydrazone (p. 728) by fusion with zinc chloride, from onitro-desoxybenzoin
(p. 828) by reduction, by the action of aniline upon brom- acetophenone, and from
phenylacetaldehyde-phenylhydrazone by the molecular rearrangement of the
/3-phenyl-indol, which first forms. It crystallizes from alcohol in colorless leaflets
and melts at 187°

/3-Methyl Indol, C8H5(CHg)NH, Skatole, occurs in human faeces (with a
little indol). It may be obtained, together with indol, from reduced indigo (p.
827), by the putrefaction of albuminoids, or (with indol) in the fusion of the same

OXINDOL. 831

with potassium hydroxide. See Berichte, 18, Ref. 80, for the isolation of indol.
In the putrefaction skatole carboxylic acid, CgHgN.COjH, first resuhs; Jhis
melts at 161°, and decomposes into carbon dioxide and skatole. It was first syn-
thesized by distilling nitrocumic acid with zinc dust. It can be prepared without
difficulty by heating propidene-phenylhydrazone with zinc chloride (p. 829). It
crystallizes from ligroine in leaflets, melting at 95°, and boils at 265°. It has a
penetrating fecal odor. For the reaction with a pine shaving, see Annalen, 236,
140.

/3-Phenyl Indol, C8H5(C5H5)NH, may be prepared by heating phenyl-ace-
taldehyde-phenylhydrazone, CgHj.CHj.CHrNjH.CgHs, with alcoholic hydro-
chloric acid (isomeric a-phenylindol is formed by fusion with zinc chloride). It
forms white leaflets, melting at 89° {Berichte, 21, 1811). Various methyl-phenyl
indols sustain analogous transpositions {Berichte, 22, Ref. 672).

Indol Carboxylic Acids.

These are produced (p. 829) when indol and alkyl indols are heated with sodium
and carbon dioxide (similar to the pyrrol carboxylic acids, Berichte, 21, 1925) ;
further by fusing the alkyl indols with caustic alkali. Ordinary oxidizing agents
do not attack them {Berichte, 21, 1929, 1937). Heated alone or with lime they
break down into carbon dioxide and indols.

a-Indol Carboxylic Acid, CgHgN.COjH, from pyroracemicphenyl hydrazone
and from a-methyl indol, crystallizes from hot water in delicate needles, melting at
200°, and decomposihg into carbon dioxide and indol.. It yields imiile anhydride,
CjgHjjNjOj {Berichte, 22, 2503) if heated with acetic anhydride. n-Methyl- and
n-Ethyl-a-indol-carboxylic acid, CjH5N(CH3)C02H, are produced from pyro-
succinnic acid with methyl and ethyl hydrazine (p. 829). They break down when
fused into carbon dioxide and methyl- and ethyl-indol.

/3-Methyl-a-Indol Carboxylic Acid, CjH5(CH3)N.C02H, skatole carboxylic
acid, results from the decay of albuminates. It crystallizes in leaflets, melting
at 165°, and decomposing into carbon dioxide and skatole. Another product,
formed at the time, is Skatole Acetic Acid, CjH5(CH3)N.CH2.C02H, melting at
130° {Berichte, 22, Ref. 701).

;8-Indol Carboxylic Acid, CgHjN.COjH, is produced when skatole is fused
with caustic potash, and upon heating indol with sodium in a current of carbon
dioxide at 230-300° (together with a little of the aacid). It crystallizes from hot
water in leaflets and melts with decomposition at 218°. Being a /3acid it cannot
yield an imide anhydride {Berichte, 23, 2296). «ir-Dimethyl-/3-indol carboxylic
acid, CgH^(CH3)N(CHj).C02H, froni methyl-phenylhydrazone-acetoacetic ester
(p. 829), melts at 200°, and decomposes into carbon dioxide and wa-dimethyl
indol.

Oxindol, CjHjNO = Z^Yi.j(^^^QO, the lactam of «-amido-phenyl acetic

acid (p. 7S5), was first obtained by the reduction of dioxindol with tin and hydro-
chloric acid, or with sodium amalgam in acid solution. It is also produced in the
reduction of aceto-o-amido-mandelic acid (p. 774) with hydrochloric acid. It
crystallizes from hot water in colorless needles, and melts at I20°. It oxidizes to
dioxindol when exposed in a moist condition ; by protracted boiling it will reduce
an ammoniacal silver solution. It has both basic and weak acid properties, forms
a stable hydrochloride, and dissolves in alkalies. If heated to 150° with baryta
water it is converted into oamido-phenyl-acetic acid (p. 756). ,CH2.C0

Oxindol boiled with acetic anhydride yields Aceto-oxiridol, Q^^'C ^ -^ ,

^N.CO.CHj
which crystallizes in long needles, and melts at 126°. It dissolves to aceto-o-

832 ORGANIC CHEMISTRY.

amido-phenyl acetic acid in sodium hydroxide (p. 756). The action of nitrous
acid upon the aqueous solution of oxindol causes a transposition and isatoxime
results (p. 837) ; this was formerly taken for nitroso-oxindol ; the latter passes, by
reduction with tin and hydrochloric acid, into the so-called Amido-oxindol,

CH(NH2),
^^6^4;; j;CO (?). Ferric chloride oxidizes this to isatin.

*\— CO— /

/CH,V

An isomeride of the last compound is HjN.CgHj^ NH /^^' i''A™''l°-
oxindol, which is produced by the reduction of dinilrophenyl-acetic acid (p. 754).
Isatoxime also results from it when it is acted upon by nitrous acid and boiled with
alcohol (Berichte, 16, 518).

Ethyl Oxindol t^jH^^' j^,„2.^ y, is obtained on boiling oxindol with

sodium ethylate (l equivalent) and ethyl iodide. It is an oil, volatile with
aqueous vapor. If it be heated with baryta water or with concentrated hydro-
chloric acid to 150° the ethyl group will not be split off (compare p. 755) [Berichte,
16, 1705). ^

Indoxyl and pseudo-indoxyl are isomeric with oxindol. The second is only
stable in its derivatives ; the two forms are therefore probably tautomeric : —

„ „ /C(OH)'^Pjj and C H /<^° ^CH

Indoxyl. Pseudoindoxyl.

Indoxyl, CjH,NO, results in the elimination of carbon dioxide from indoxylic
acid (see below). This is best effected by boiling with water. It is an oil not
volatile in aqueous vapor, and is rather easily soluble in water, showing yellow
fluorescence. It is very unstable, and in aqueous or slightly acid solution is readily
resinified. It dissolves with a red color in concentrated hydrochloric acid. It is
a\i^Vie6.'\6 indigo blue when its alkaline solution (best ammoniacal) is exposed to
"'the air. Ferric chloride and hydrochloric acid effect the conversion more quickly : —

2C8H,NO + 20 = Ci,Hj„N,0, + 2H,0.

When indoxyl is digested with potassium pyrosulphate, SjO^K^ (compare p.
670), we get potassium indoxylsulphate, CgHjN.O.SOgK, which crystallizes from
hot alcohol in shining leaflets. .This i^ig(j|g4 i15".the Urine of herbivorous animals
(Urine indican), generally after'Tftfe"ln%estion of indol. When digested with acids
the salt decomposes into sulphuric acid and indoxyl, which forms indigo blue by
the addition of a little ferric chloride (an excess of ferric chloride destroys the
indigo). We proceed similarly in the detection of indoxylsulphuric acid in urine.

The presence of the imide group in indoxyl is proven by the formation of a
nitrosamine and a phenyl-diazo compound (^Berichte, 16, 2190); the existence of
a phenol-like hydroxyl is inferred from the production of indoxylsulphuric acid
and of ethyl-indoxyl (see below).

Indoxylic Acid, CgH^NOj =C^Yi/^^^^^C.CO^\i., corresponding to

indoxyl, is produced from its ethyl ester by fusion with caustic soda at 180° [Be-
richte, 17, 976). Acids precipitate it from its salts in the form of a white crys-
talline precipitate. It melts at 123°, with decomposition into carbon dioxide and
indoxyl. Like the latter, it is oxidized to indigo blue. Its ethyl ester is obtained
by reducing o-nitrophenyl propiolic ester with ammonium sulphide, or isatogenic
ester with zinc and hydrochloric acid and from indoxanthic ester (p. 833). It
crystallizes in thick prisms, and melts at 120°. When digested with sulphuric acid
it affords a quantitative yield of indigo-sulphonic acid. It possesses a phenol

INDOXANTHIC ESTER. 833

character, dissolves in allcalies and is again precipitated by carbon dioxide. Ethyl
iodide converts the phenol salts into Ethyl Ethoxy-indoxylic Ester, C,H.

C(O.C,H,)
{ ^.C.COj.CjHj, which by saponification with baryta water, forms

\ NH /

Ethoxy-indoxylic Acid. The latter consists of brilliant needles, melting at
160°. It yields indoxyl when digested with hydrochloric acid (just as in the case
of ethyl indoxyl), and this gives indigo blue with ferric chloride.

If fused it separates into carbon dioxide and

qo.c.Hj

C ^CH. The latter is an oil, volatile in steam, and having an odor

\ NH ^

like that of indol, which it resembles in other respects. Nitrous acid converts it
into a nitrosamine {Berichte, 15, 781).

Pseudo-indoxyl' (see above) is known only in its derivatives. Its isonitroso-

compound, CgH^(^„TT J)C(N.OH), formerly considered nitroso-indoxyl, is pro-
duced by the action of nitrous acid upon ethoxyindoxylic acid. A transposition
occurs here. It is identical with pseudo-isatoxime (p. 837).
The derivatives of pseudo-indoxyl —

CeH.<^?i)C:CH.CeH3 and C,H ,(^0 Xqc/^Hs^^

are similarly obtained from indoxyl or indoxylic acid by condensation with benzal-
dehyde and pyroracemic acid. They are called the indogenides of the latter
compound, and are perfectly similar to pseudo-isatin etkoxime (p. §3?). The

divalent group, CsHj^^j^tr^C =, is termed indogen {Berichte, 16, 2197).

The condensation of isatin with benzenes produces perfectly analogous indogen-
ides. In this case the isatin changes to pseudo-isatin, CgH^^ -^^ ^CO.

Indirubin, CigHijN202, is of this class. It is isomeric with indigo-blue,
and appears in nearly all the indigo syntheses, and in its entire character is very
similar to this substance. It is produced by effecting the condensation of indoxyl
(pseudo-indoxyl) with isatin (pseudo-isatin) by means of a dilute soda solution
(^Berichte, 17, 976), and therefore, may be called an indogenide of pseudo-
isatin : —

CaH /^^>CH, -F C0(c^0 \nH =
Pseudo-indoxyl, Pseudo-isatin.

Indirubin.

In the same manner indoxyl may be oxidized (by the union of two pseudo-
indoxyl groups with separation of water) to indigo-blue, which, therefore, is to be
considered a di-indogen {Berichte, 16, 2204).

Indoxanthic Ester, C„HiiNO, = C^n/^^C{OVL).CO^.C^YL^, results

from the oxidation of indoxylic ester with ferric chloride or chromic acid. It
yields a nitrosamine with nitrous acid {Berichte, 15, 774). Further oxidation pro-
70

834 ORGANIC CHEMISTRY.

duces anthranil oxalylic ester, C^tli('j^^QQ ^-.q j^ (p. 749)— this is analogous

to the formation of aceto-anthranilic acid (p. 830) from methyl ketok Indoxanthic
ester reverts to indoxylic ester when reduced.

Isatogenic Ester, CnHjNOi = C^}ii<^ /\ (?), is obtained by

^ N — O
a transposition of the isomeric o-nitrophenyl propiolic ester when it dissolves in
concentrated sulphuric acid (p. 815). It crystallizes in yellow needles, melting at
115°- Various reducing agents convert it into indoxylic ester, but with ferrous
sulphate we get indoxanthic ester. In the solution of free 0 nitrophenyl acetic
acid in sulphuric acid, the free Isatogenic Acid, CgH^.NOj.COjH, is very pro-
bably produced; it cannot, however, be isolated. Isatin, CjHjNOj, exists in the
solution diluted with water.

Di-isatogen, CjgHjNjO^, isomeric with the preceding, is similarly formed
by dissolving ^-dinitrophenyl-diacetylene (p. 802) in sulphuric acid (by the union
of two isatogen groups, C5H4:(C2N02). It crystallizes in red needles and by re-
duction yields indigo-blue : —

C,6H,N,0^ + 3H2 = qeHioNjO, + 2H,0.

On adding sulphate of iron to the solution of isatogenic ester, di-isatogen or
o-nitrophenyl propiolic acid in sulphuric acid, the solution becomes blue in color
and Indoin, C3 2H2„N405 (?), separates. This is very similar to indigo-blue.
It is also formed by adding »-nitrophenyl propiolic acid to the solution of indoxyl
or indoxylic acid in sulphuric acid.

Di-oxindol, CgH^NOj = C^H^/^^^-^^^CO, is the lactam of o-amido-

mandelic acid, not capable of existing in a free condition, or hydrindic acid (p. 773).
It is more readily obtained by boiling isatin with zinc dust, water and a slight
quantity of hydrochloric acid. It is rather easily soluble in water and alcohol,
crystallizes in colorless prisms, melting at 180° and decomposing about 195° with
formation of aniline. It oxidizes readily in aqueous solution to isatid and isatin.
It forms salts with bases and acids ; it combines with two equivalents of the
former. Nitrous acid converts it into the nitroso-compound, CgHg(N0)N02,
melting at 300° and subliming in white needles. Di-oxindol heated with acetic

anhydride to 140° yields uceto-oxindol C^}l^'(^.^,Af. ^h \ >, melting at 127°,

and dissolving in baryta water with the formation of aceto-u-amido-mandelic acid
(p. 774).

Isatin, CgHjNOj, is the lactime of <?-amido-phenyl-glyoxylic acid
or isatinic acid (p. 762), whose lactam, the hypothetical pseudo-
isatin, is known only in its derivatives : —

Isatin. Pseudo-isatin.

Isatin was first obtained by the oxidation of indigo. It is also
prepared from oxindol by transposition into the so-called amido-

ISATIN. 83s

oxindol (p. 831) and then oxidizing the latter with ferric chloride.
It arises in a similar manner from indoxyl. Its ready formation
from (7-nitro-phenyl-propiolic acid by boiling with alkalies (p. 815),
and by the decomposition of isatogenic acid (p. 834), is worthy of
remark. It is also obtained from a-oxyquinoline (carbostyril) in its
oxidation with potassium permanganate.

The easiest method of preparing isatin consists in oxidizing indigo with nitric
acid [Berichte, 17, 976). To purify it, dissolve it in potassium hydroxide, add
hydrochloric acid as long as a black precipitate is formed, and then treat the filtrate
with hydrochloric acid.

Isatin crystallizes in yellowish-red monoclinic prisms, melting
at 201°, and subliming partially undecomposed. It dissolves in
water and alcohol with a reddish-brown color. It dissolves in caustic
alkalies (equivalent quantities), forming salts, e. g., CgH^NKOj. The
solution, violet at first, soon becomes yellow, with the production of
isatinates; digestion with excess of alkali causes the immediate
transformation. Acids liberate the readily soluble isatinic acid from
its salts ; and on standing, more quickly upon the application of
heat, this changes to isatin, at the same time assuming a yellowish-
red color. Isatin also possesses a ketone-like character ; it unites
with alkaline bisulphites to crystalline compounds, with hydroxyla-
mineto isatoxime (p. 837), and with phenyl-hydrazine hydrochloride
to a yellow compound, melting at 210°, which may be employed in
detecting isatin {Berichte, 17, 577).

Isatin unites with phenylisocyanate, forming carbanilido-isatin. It affords a dark
blue solution with benzene containing thiophene and sulphuric acid (p. 530). Water
precipitates a blue dye, indophenin, CjjHjNOS = (CgHjNOj -j- C4H^S — H^O)
{Berichte, 18, 2638).

Two molecules of phenol, toluene or dimethyl- aniline and isatin are condensed
by concentrated sulphuric acid to colorless compounds, derivatives of pseudo- isatin,
C,H^/ ^Wz^CO ^^serichte, 18, 2639).

Isatoic acid is formed when isatin is oxidized with chromic acid in glacial acetic
acid solution (p. 749).

Isatin yields nitrosalicylic acid when oxidized with nitric add, and aniline
when fused with potassium hydroxide. When reduced (boiling with zinc dust,
etc.), it first becomes dioxindol (a derivative of pseudo-isatin) ; with ammonium'
sulphide we get an intermediate product — isatid, CjjHjjNgOi. This is a color-
less powder, readily re-oxidizing to isatin.

In a solution of potassium-isatin, or in one of ammonia containing isatin,
silver nitrate precipitates silver isatin, CgH^AgNOj, a red compound. Chlorine
and bromine (in glacial acetic acid) convert isatin into substitution products,
which conduct themselves just like isatin, and if dissolved in alkalies yield sub-
stituted isatinic acids. Nitration in the cold produces nitroisatin, C^'KJ^NO^
NOj — red needles, melting at 230°.

If ammonia should act upon isatin suspended in ether, there will result Imesa-
tin, C8H5NO(NH), forming dark yellow crystals, and when digested with alka-
lies or acids, decomposing again into isatin and NHj. Tolyl-methylimesatin,

836 ORGANIC CHEMISTRY.

CjH4(CH3)NO(N.C,H,), is an analogous compound. It contains the residue of
paratoluidine, C6H4(CH3)N=, in place of the NH-group. It is obtained by
heating/-toluidine with dichloracetic acid (by condensation) {Berichie, 16, 2261).
Concentrated hydrochloric acid decomposes it (like imesatin) into toluidine and
^-Methylisatin, CjH4(CH3)N02 = C„H3(CH3).C2N02H. The latter re-
sembles isatin; with PCl^ it affords /-Methylisatin chloride, CjH4(CH3)NOCl,
which (in the same manner as isatin chloride, etc.), may be converted into di-
methyl indigo-blue, Ci6Hj(CH3)2N202 (methylated in the benzene nucleus),

Isatin Chloride, Q-^/ ^ ^ CCl, is produced by digesting

isaiin with PCI5 (in benzene solution). It crystallizes in brown
needles and dissolves with a blue color in ether, alcohol and glacial
acetic acid. Hydriodic acid or zinc dust acting on its glacial acetic
acid solution produces indigo-blue : —

.CO. .CO.CiCCO.

2CeH/ \CC1 + 2H, =C,H / / \ )CeH^,+ 2HCI.

We can also obtain from the substituted isatins (brom-, nitro-,
methyl-isatin) substitution products of indigo blue, dibrom-, di-
nitro, and dimethyl-indigo-blue {Berichte, 12, 456).

Ether derivatives of isatin and pseudo-isatin : —

CO CO

CeH / >C(0.CH3) CeH / _\C0
\ N ^ ^N(CH3)

Methyl-isatin. Methyl-pseudo-isatin.

The alkyl isatins result from the action of alkyl iodides upon silver-isalin, and
are blood-red colored crystalline bodies. Methyl-isatin, C8H4N02(CH3), melts
at 102°. Ethyl dibrom-isatin, C8H2Br2N02(C2H5l, at 88°. They are saponi-
fied by alkalies, and yield salts of isatin and isatinic acid. Acids separate isatin
from these. Ammonium sulphide with air contact converts them at once into
indigo blue {Berichte, 15, 2093).

When isatin is boiled with acetic anhydride a transposition occurs and we ob-

/CO CO

tain Aceto-pseudo-isatin, CgH^^ .j^,p„ j-,tt ,>, crystallizmg in yellow

needles, and melting at 141°. When digested with water or acids it splits into
acetic acid and isatin. It dissolves in alkalies, forming salts of aceto-isatinic acid,

/CO CO TT
^6^4\ luHfrO CH 1 ^P' 7^^)' which decompose on warming into isatinates and

acetic acid.

Ethylpseudoisatin (see above) is obtained by the reduction and subsequent
oxidation of ethoxypseudo-isatin-ethoxime (see below). It crystallizes in large,
blood-red crystals, melting at 95°. It dissolves immediately in alkalies with a yellow

/CO CO I-T
color, forming salts of ethyl isatinic acid, CjH^^ ^-^ „ \, , from which acids at

once separate ethylpseudo-isatin {Berichte, 16, 2193). The latter is also obtained
from ethyl indol (p. 830), by oxidation with a hypobromite {Berichte, 17, 566).
Methyl-pseudoisatin, foimed in the same "way, consists of red needles, melting
at 134°.

INDIGO. 837

Isonitroso- derivatives of Isatin and Pseudoisatin : —

Isatoxime. Pseudo-isatoxime.

Isatoxime, CjHjNjOj (IsatiiiTOxime), was first obtained by the action of
nitrous acid upon oxindol (p. 851), and was, therefore, formerly considered nilroso-
oxindol. It is also prepared (analogous to the formation of the acetoximes,
from isatin and hydroxylamine; or from para-amidooxindol (p. 832), by action
of nitrous acid, and boiling with alcohol [Berichte, 16, 518). It crystallizes
from alcohol in yelloiff needles, and melts at 202°, with decomposition. It
dissolves with a yellow color in the alkalies. When reduced with tin and hydro-
chloric acid it yields so-called amido-oxindol (p. 832). By the successive action
of ethyl iodide upon the silver salt we obtain a mono-, and a diethyl derivative
from which isatin [Berichle, 16, 1706) is formed by reduction and subsequent
oxidation.

Pseudo-isatoxime (see above) is prepared (by transposition) by the action of
nitrous acid upon ethyl indoxylic acid. It was formerly considered nitroso-in-
doxyl (p. 833). It crystallizes from alcohol in shining yellow needles, and de-
composes at about 200°. It does not give the nitroso reaction. It dissolves in
alkalies and is separated again by carbon dioxide {Berichte, 15, 782). Ethyl
iodide and sodium ethylate convert it into : —

.CO.qN.O.CjHj) .CO.C(N.O.C2HJ

C,H / / and CeH / /

\nH \ N.CjHj

Pseudoisatin-ethoxime. Ethoxypseudoisatin-ethoxime.

This first yields isatin by reduction and oxidation (as does isatoxime and its two
ethers, loc. cit.). The same treatment applied to ethoxy-pseudo-isatin-ethoxime

-CO.CO
yields ethylpseudoisatin, C„H,<f / (see above). The reduction of ethyl.

■ ^N(C,H5) ;

pseudo-isatin-ethoxime with ammonium sulphide produces diethyl indigo, in which
the two ethyl groups are united to nitrogen (Berichte, 16, 2201) : —

.CO.CO CO.C=^=:C.CO.

2CeH / / + 2H, = C3H / / \ )CeH, + 2H,0.

\ N(C,H5) \ N(C,H5)(C,H,)n/

-C. — CHO
Anthroxan Aldehyde, CgH^NOj = CgH^:^ | ^„ (with an atomic

grouping similar to that of isatogenic ester), is isomeric with isatin, and is formed
when o-nitrophenyl glycidic acid (p. 777) is boiled with water (together with
anthranil) {Berichte, 16, 2226). Silver oxide converts it into anthroxanic acid,
CjH^NO.CO^H.

INDIGO-BLUE.

Indigo-blue or Indigotin. This commercially important
chromogen is found in ordinary indigo and possesses the molecular
formula, CieHioN^Oj, which is in acford with its vapor density.
The innumerable synthetic methods for its production, already

838 ORGANIC CHEMISTRY.

mentioned, were discovered by A. von Baeyer. The most important
of these are: the reduction of isatin chloride (p. 836) first with
phosphorus (1870), then with zinc dust or HI (1879); the trans-
formation of i7-nitrophenyl propiolic acid (p. 815) by digestion
with alkalies and reducing agents (1880); the condensation of
i7-nitrobenzaldehyde with acetone in alkaUne solution (pp. 719 and
730), acetaldehyde and pyroracemic acid (p. 815) (1882) ; and the
conversion of a-dibrom-(7-nitro-acetophenone (p. 728) by boiling
with alkalies (1882) {Berichte, 17, 963). •

Recently several very simple syntheses of indigo-blue have appeared : —

1. Fusion of bromacetanilide, CjHj.NH.CO.CHjBr, with caustic potash, and
oxidation of the aqueous solution of the product by air. The indoxyl or pseudo-
indoxyl formed at first is then oxidized to indigo blue (Flimm, Berichte, 2^,^^).

2. Indigo can also be formed by fusing phenylglycocoll, CjHj.NH.CHj.COjH,
virith potassium hydroxide, etc., as well as from anthranilic acid (Heumann, Be-
richte, 23, 3043, 3431 ; Biedermann, Berichte, 23, 3289).

According to A. von Baeyer's investigations the constitution of
indigo blue is very probably expressed by the formula : —

,CO— C=C— CO-

This accounts best for its entire deportment and all its transforma-
tions.

According to this formula indigo-blue contains two indol groups, CjH^^' ^ . ,

in combination with each other. That the union is through the carbon atoms fol-
lows from the synthesis of indigo-blue from o-dinitro-diphenyl-diacetylene (p. 802)
and, therefore, diphenyl-diacetylene, CgHj.C-C.CjC.CjHj, may be looked
upon as the parent hydrocarbon of indigo-blue. This we infer also from the
formation of indigo-blue from the indoxyl and isatogenic derivatives, which is
analogous to that of the indogenides (p. 833). As arguments for the existence of

/CO C
the group, CjH^cf -^r ^ , we have the production of indigo-blue from isatin

chloride and the isatin ethers (p. 836), as well as from brom-acetophenones (see
above); from the indoxyl compounds, from indoxanthic ester and di-isatogen
(p. 834). Another support for this view is the fact that only those derivatives of
o-nitro-cinnamic acid, C5H4(N02).CH:CH.COjH, yield indigo in which the carbon
atom joined to the benzene nucleus is also in connection with hydroxyl or oxygen;
thus the o-nitro-phenyl-oxyacrylic acids (p. 777) and not the o-nitro-cinnamic acid
yield indigo. The condensation products of onitrobenzaldehyde behave similarly;
o-nitrophenyllactic methyl ketone, C5H4{N02).CH(0H).CHj.C0.CH„ yields
indigo, but o-nitro-cinnamyl-methyl ketone (p. 806) does not. With the latter
bodies (in the formation of indigo-blue) there occurs a splitting-off of the excessive
carbon atoms of the side-chains in the form of formic acid, acetic acid, etc.

Finally, the presence of 2 NH groups in indigo-blue is rendered very probable
by the formation of di-ethyl indigo from ethyl pseudo-isatoxime (p. 837).

In the production of indigo-blue from indoxyl derivatives there occurs, in all
probability, a conversion of indoxyl into pseudo-indoxyl and pseudo-isatin, and

INDIGO-BLUE. 839

this leads us to regard indigo-blue as a di-indogen, corresponding to the indogen-
ides of benzaldehydes, etc. (p. 833). The absorption of two hydrogen atoms
reduces indigo-blue to indigo-white, CijHuNjOj, which has the character of a
phenol. In this reaction the doubly united carbon atoms are at first saturated and
then the indogen group is changed to the indoxyl group : —

,CO— CH— CH— CO,

yields

.qOHvC— C:(HO)C.
p TT / ^ — -^__^ \r* TT

Indigo-white.

Indigo-blue constitutes the principal ingredient of commercial
Indigo, derived from different IndigofercB and from woad {Isatis
tinctorid). It occurs in these plants as a glucoside, called indican,
which parts with its variety of glucose and becomes indigo-blue,
when boiled with dilute acids, or if acted upon with a ferment (if
the various portions of the plant be covered with water and exposed
to the action of the air). The indigo-blue separates in the form of
a powder.

Commercial indigo is a mixture of several substances, of which the indigo-
blue is alone valuable. Boiling acetic acid extracts indigo gluten from it ; and
dilute potassium hydroxide takes out indigo-brown, which is precipitated as a
brown mass by sulphuric acid. The residue finally yields to boiling alcohol the
indigo-red, a red powder which dissolves in alcohol and ether with this color.
The residual mass is almost pure indigo-blue.

Indigo-blue can be obtained from commercial indigo by sub-
limation, but it nearly all decomposes by the operation. It is ad-
visable to first reduce indigo to soluble indigo-white, which can
then be oxidized to indigo-blue by the exposure of the alkaline
solution to the air.

Grape sugar is the best reducing agent for indigo. The latter, in a finely di-
vided state, is mixed with an equal weight of grape sugar, and upon this are
poured lyi, parts concentrated caustic soda and hot alcohol or water (150 parts),
and the whole allowed to stand in a closed flask filled with the same liquid for
some hours. The clear yellow solution is next poured into dilute hydrochloric
acid and shaken with air (Annalen, 195, 305).

Indigo-blue or indigotin is a dark-blue powder with a reddish
glimmer j it becomes metallic and copper-like under pressure. It
sublimes in copper-red, metajlic, shining prisms. It is insoluble in
water, alcohol and ether, in alkalies and dilute acids, and is odor-

840 ORGANIC CHEMISTRY.

less and tasteless. It dissolves in hot aniline with a blue, in molten
paraffin with a purple-red color, and can be crystallized from these
solvents. It crystallizes from hot oil of turpentine in beautiful
blue plates. At 300° it is converted into a dark-red vapor. If
boiled with potassium hydroxide and manganese peroxide, it yields
anthranilic acid (p. 748) ; aniline results on distilling with potas-
sium hydroxide. See Berichte, 18, 1426, for the absorption spec-
trum of indigo and its derivatives.

We will yet mention some of the substituted indigotins, which are quite similar
to indigotin and have been prepared synthetically.

Dichlor, brom-, nitro-indigoes result from the substituted isatins (p. 836), and
from brom o-nitroacetophenones (p. 838). A dichlor-indigo has been prepared
from o-nitro-OT-chlorbenzaldehyde {Berichte, 18, Ref 8). Tetrachlor-indigo is
obtained from «-nitro-dichlor-benzaldehyde [Berichte, 18, Ref. 470). Dimethyl'
indigoes result from nitro-OT-toluic aldehyde (p. 721) and/-methyl-isalin (p. 836).
Diethyl indigo (its imide groups contain ethyl) is obtained from ethyl-pseudo-isa-
tin-ethoxime (p. 837). Di-isopropyl indigo, cumin indigo, is derived from
o-nitro-cumenyl prcpiolic acid [Berichte, 19, 261). Indigo-dicarboxylic acid,
CigH8N202(C02H)2, may be prepared from nitro-phenylpropiolic acid. It dis-
solves in alkalies with a bluish green color [Berichte, 18, 950).

The isomerides of indgotin are indigo-red, present in commercial indigo,
indirubin, the indogenide of pseudoisatin (p. 833), indigo-purpurin, formed
together with indigotin from isatin chloride (p. 836) and indin. The latter is
obtained by the action of alcoholic potassium hydroxide upon isatid (p. 835), or by
boiling dioxindol with glycerol. Di-isatogen, CijHgNjO^, and indoin (p. 834)
bear a close relation to indigotin.

Indigo White, CisHijNjOj, is obtained by the reduction of
indigo-blue (see above). It can be precipitated from its alkaline
solution by hydrochloric acid (air being excluded) as a white crys-
talline powder, soluble in alcohol, ether and the alkalies, with a
yellowish color. It rapidly re-oxidizes to indigo-blue by exposure
to the air. It yields di-indol when heated with baryta-water and
zinc dust.

When indigo-blue is dissolved in concentrated sulphuric acid (8-15 parts) and
digested for some time, we get indigotin monosulphonic acid, CjjHgNjO^.SOjH
(phoenicin sulphuric acid), and indigotin disulphonic acid, Ci5HgN202(S03H)2
(coerulin sulphuric acid). Water precipitates the former from its solution as a
blue powder, soluble in pure water and alcohol, but not in dilute acids. Its salts
with the bases possess a purple- red color and dissolve with a blue color in water.

The "disulphonic acid is obtained when indigo is digested with strong, fuming
sulphuric acid. It can be absorbed from its aqueous solution by clean wool and
again removed from the latter by ammonium carbonate. Its alkali salts, e. g.,
Ci5HjNj02{S03K)2, are sparingly soluble in salt solutions, and are thrown out
from their solution in the form of dark-blue precipitates by alkaline carbonates and
acetates. They constitute in commerce what is known as indigo-carmine. When
the indigotin sulphonic acids are reduced, they yield, just as does indigo-blue, the
indigo-white sulphonic acids.

Goods (wool) are dyed in two ways with indigo : the wool is immersed in the

BENZO-AZOLE COMPOUNDS. 841

aqueous solution of indigotin sulphonic acid (Saxony-blue dyeing), or the indigo-
blue is changed by fermentation to indigo-white (*ndigo-vat), the cloth saturated
•with the latter and exposed to the air, when indigo-blue forms and sets itself upon
the fibre. In printing, a mixture of o-nitrophenyl propiolic acid and an alkaline
reducing agent (potassium xanthate, etc.) are sometimes substituted for the indigo.
Steaming causes the formation of indigo-blue.

4. BENZO-AZOLE COMPOUNDS.

The benzoazoles or benzodiazoles attach themselves to indol or benzopyrrol
(p. 826). They contain a " five-membered ring " with two nitrogen atoms (p. 551).
Like the azole derivatives they occur as a- or (i, 2)-diazoles (with two adjacent
«-atoms) and as /3- or (i, 3)-diazoles. The first are known in two forms, inda-
zoles and isindazoles (benzopyrazoles). The ^-benzodiazoles contain (in addition
to the benzene ring) the ring of glyoxaline (p. 551) ; hence they may be termed
Benzoglyoxalines [Annalen, 227, 303; Berichie, 18, Ref. 223): —

CH CH NH

c,h/^>nh c,h/^^)n c,h/^\ch

a-Benzodiazole, Benzopyrazole, j8-Benzodiazole,

Indazole. Isindazole. Benzoglyoxaline.

(i) Indazole, CjHgNj, is formed by heating o-hydrazine-cinnamic acid,

CgH^C TJij-Nrtr ^ ' when acetic acid is eliminated. It crystallizes from hot

water in colorless needles, melting at 146°, and boiling at 270°. It is soluble in
dilute acids. Its salts are very unstable. It yields «-ethyl indazole, CjHjNj
(C2H5), when it is heated with ethyl iodide.

qCHj)
a-Methyl Indazole, C^/ \ X-vttt j is derived from o-hydrazine-aceto-

phenone, CsH^/^^^^ . It melts at 1 1 3° and boils at 280°.

" C— CHj.CO^H

a-Indazole Acetic Acid, C.H,^' I \hjtt . results from the oxidation

of o-hydrocinnamic acid, in alkaline solution, on exposure to the air. It crystal-
lizes from hot water in yellow needles, melting at 168-170°, decomposing at the
same time into carbon dioxide and o-methyl indazole.

(2) Isindazole or Benzo-pyr azole compounds (see above) were formerly con-
sidered to be quinazole derivatives (they contain a side-chain of six members).
Isindazole, C,H,N», the parent substance, is only known in its derivatives.

/CH,.CO,H

«Ethyl-isindazole Acetic Acid, C^H^^ ^^=== N , is formed when

N(C,H5)/

842 ORGANIC CHEMISTRY.

, ^, , , , . . . .J f, Ti /CH:CH.CO„H

the aqueous solution of ethyl hydrazine-cinnamic acid, '--6"4\NfC H ) NH

is shaken with air. It melts at 131°, and at 162° breaks down into carbon dioxide
and ethyl-methyl isindazole.

«■ Ethyl-methyl Isindazole, CsH^;' ,, called ethyl qmnazole, is

^N(C,H,)/

/PO PIT
derived from nitrosoethyl-«-amidoacetophenone, ^e^iC-^tc h') NO' ^ yellow

oil, that solidifies in the cold to a leafy mass, melting at 30°. It forms salts with
acids; much water, however, decomposes them {Berichte, 18, Ref. 227).

There is a compound formed by the condensation of the product resulting from
the action of diazobenzene chloride upon dinitro-phenylacetic ester {Berichte, 22,
321 ; 23, 714), that should probably be included among the isindazole derivatives.

(3) Benzo-glyoxaline compounds (see above), condensation products of the
tf-phenylene diamines, have been described with the latter, and there designated as
anhydrobases or aldehydines (p. 627). ,NH,

Benzo-glyoxaline, CjHgNj = C^H^C^ /CH, is ordinarily known as
phenylene methenyl amidine (p. 628). ^ N ^

(4) We may yet add to the benzo-diazoles (or imidazoles) the benzo-oxazoles
and benzo-thiazoles. These not only contain the benzene-ring but also those of
oxazole and thiazole (pp. 554, 555) : —

C,H,/°\CH and C,h/^)cH.

Benzo-oxazole Benzthiazole,

Methenylamidophenol. Methenylamidothiophenol.

They have been obtained as condensation products of o-amidophenol and
u-amidothiophenol, hence are usually treated with these (p. 679).

DERIVATIVES WITH TWO OR MORE BENZENE NUCLEI.

Although in general very stable the benzenes yet possess to a
high degree the power, by exit of hydrogen, of combining with
each other in part directly, and partly by the assistance of other
carbon atoms. The hydrocarbons derived in this manner yield
numerous derivatives.

They may be classified as follows: (i) those with directly com-
bined benzene nuclei, diphenyl derivatives; (2) th'ose in which the
benzene nuclei are joined by i carbon atom, di- and triphenyl
methane derivatives ; (3) those with benzene nuclei linked together
by two or more carbon atoms, ///^^wz)'/ derivatives ; (4) those with
condensed benzene nuclei, naphthalene and anthracene defivatives.

I. Derivatives of directly combined benzene nuclei.

DIPHENYL. 843

DIPHENYL GROUP.*

(i) Diphenyl, QjHio = CeHs.CgHs, results from the action of
sodium upon the solution of brom-benzene in ether or benzene :
aCeHjBr -\- Naj = C12H10 -j- zNaBr. It is also produced in slight
amount when benzoic acid is distilled with lime (together with
traces of benzene). It is present in that portion of coal-tar which
boils about 240-260°.

Preparation. — Conduct benzene vapors through an iron tube heated to redness.
The tube is filled with fragments of pumice stone. The yield of the diphenyl is
about 50 per cent, of the benzene taken [Berichte, 10, 1602). It may be obtained
from aniline by converting the latter into diazobenzene sulphate and decomposing
the latter with copper or zinc dust (p. 634) [SericAte,2'i, 1226).

Diphenyl crystallizes from alcohol and ether in large, colorless
leaflets, melting at 71°, and boiling at 254°- If dissolved in glacial
acetic acid and oxidized with chromic anhydride it yields benzoic
acid.

Metallic sodium reduces diphenyl, dissolved in amyl alcohol, to tetra-hydro-
diphenyl, CjjHj^, boiling at 245°. The latter readily forms a dibromide which
alcoholic potash converts into dihydro-diphenyl, CjjHjj, boiling at 248° (Be-
richte, 21, 846).

The halogens, nitric acid and sulphuric acid convert diphenyl into mono- and di-
substitution products. In the first, e.g., CjjHgBr, Cj2Hg(N0j), CjjHgSOjH, the
substitution groups occupy the para-position, referred to the point of union of the
two benzene nuclei. When these are oxidized with chromic acid we obtain para-
derivatives of benzoic acid, the other benzene nucleus being destroyed. The
di-derivatives, e.g., Cj^HjEr^, occur in two isomeric modifications. The di-para-
derivatives predominate ; in these the two side-chains have the para-pbsition
referred to the point of union. Chromic acid oxidizes them to two para-derivatives
of benzoic acid; thus from brom-nitro diphenyl we get para-brom and para-nitro-
benzoic acid.

The energetic chlorination of diphenyl and its derivatives (p. 580), produces
perchlor-diphenyl, Cx'^\a ' brilliant plates or prisms, melting above 280°, and
boiling at about 440°. Like perchlor-benzene, it is very stable, and does not un-
dergo any further decomposition.

The nitration of diphenyl in the cold, or when dissolved in glacial acetic acid,
yields two nitro diphenyls, CjjHg(N02) ; the para-compound is not soluble in
alcohol, melts at 113°, boils at 340°, and when oxidized with chromic acid be-
comes para-nitro-benzoic acid. The other nitro-diphenyl (vei^ probably ortho)
forms plates, melting at 37° and b'oiling at 320°.

Fuming nitric acid produces o- and ;8-dinitro-diphenyl, Cj2Hg(N02)2 ; the
former (dipara) is very sparingly soluble in hot alcohol, and melts at 233°, and
by reduction yields diphenylin. The dimeta-compound, from dinitro-benzidine,
melts at 197°.

(2) Phenyl Tolyls, CgHj.CgH^.CH,, Methyl Diphenyls. The para-compound,
like diphenyl, results from the action of sodium upon a mixture of brombenzene

* Consult Annalen, 207, 363, for a tabulation of these diphenyl derivatives.

844 ORGANIC CHEMISTRY.

and ^-bromtoluene. A liquid boiling at 265°, and solidifying below 0°. Its
sp. gr. is 1.015. Chromic acid oxidizes it to p diphenyl carboxylic acid and tere-
phthalic acid.

(3) Ditolyls, CHj.CjH^.CgHjCHj, dimethyl diphenyls. The di-para-com-
pound is produced by the action of sodium upon /-bromtoluene. It melts at 121°
and distils without decomposition. It yields //-diphenyl dicarboxylic acid (p. 850)
when oxidized^ ?«OT-Ditolyl has been obtained from o-tolidine by the substitution
of the two NHj-groups. It is an oil boiling at 289° [Berichte, 21, 1096J.

Amido-derivatives.

Amido-diphenyls, C5H5.CgH5.NH2. The ortho compound, from o-nitrodi-
phenyl, melts at 4.5°. The para compound, xenylamine, crystallizes from hot water
in colorless leaflets, melts at 49° and boils at 322°.

I. Diamido- diphenyl, CjjHsCNHj)^. (i) (di-para), Benzidine
(4,4) is obtained : by the reduction of ^-dinitrodiphenyl ; and by
the action of sodium upon para-brom-aniline. It is technically pre-
pared from azobenzene by the action of tin and hydrochloric acid
upon its alcoholic solution {Annalen, 207, 330) ; the hydrazo-
benzene formed at first rearranges itself to benzidine (p. 649) (com-
pare Berichte, 23, 3265). In the cold the latter is the chief product.
Diphenylin is also formed on the application of heat : —

C5H5.NH— N-H.CjH5 yields H^N.C^H^— CgH^.NH,.

Benzidine dissolves easily in hot water and alcohol, crystallizes
in silvery leaflets melting at 122°, and subliming with partial de-
composition. It forms salts with two equivalents of acid ; the
sulphate,

q,H,(NH2)2.SO,H2,

is almost wholly insoluble in water. It oxidizes to quinone if
boiled with manganese dioxide and dilute sulphuric acid.

Consult Berichte, 23, Ref. 644, for the compounds of benzidine with aldehydes.

ijo-Dinitrobenzidine, Cj2H,(N02)j(NHj)j(NHj:N02 = 4:3),* (is formed on
nitrating diacelobenzidine. Red crystals, melting at 220°. When the two NH^-
groups are substituted it forms »«OT-dinitrodiphenyl) (p. 843). SnClj reduces it to
00-diamidobenzidine.

The nitration of benzidine in concentrated sulphuric acid gives rise to mm-Hi-
nitrobenzidine, Cj2H5(NOj)2(NH2)2(NH2:N02 = 4. 2), crystallizing in yellow
leaflets, melting at 214° {^Berichte, 23, 795). ' When reduced it yields mm-di-
amido-ienzidine (\ea.&ets meldng at 165°), which loses NH, and forms diamido-
carbazol, Ci2He(NH_2)2:NH (p. 847) (Berichte, 23, 3252). •

When benzidine is heated with concentrated sulphuric acid (2 parts) to 210°
[Berichte, 22, 2464) it becomes oo-Benzidine-disulphonic Acid, C,2H5(NH2)2
(S03H)2(NH2:S03H = 4:3) ; its diazo-derivatives are feeble dye-stuffs.

* The terms 0- and m- with the benzidine derivatives refer to the amiflo-groups ;
in the case of diphenyl to the points of union (p. 843) (Berichte, 23, 3268).

BENZIDINE DYES. 845

mm-BcDzidine Disulphonic Acid (NHjiSOjH = 4 : 2) is prepared by the
reduction of an alkaline solution of w«-nitro-benzene sulphonic acid and its further
transposition {Berichte, 22, Ref. 785). It does not yield dye-substances; they
may be obtained from the diamido-diphenylene oxide (H^N.CgHjjjO, prepared by
fusing it with caustic potash. Benzidine Sulphone, Ci2H8(NH2)2S02, is pre-
pared by heating benzidine sulphate with fuming sulphuric acid (Berichte 21,
Ref. S73; 22, 2467).

/j*-Oxyamido-diphfenyl, HjN.CgH^.CgH^.OH, is formed by replacing the
NHj-group of benzidine by hydroxyl. It yields a yellow color with salicylic acid
and a reddish violet with i-naphthol-4-sulphonic acid.

z. ?«?«-Diamido-diphenyl, Vi.^^<Z^Yi.^.Q.'^Yi.^M^^{<Z^MU^ = 1:3), is
formed when eliminating the two NHj-groups from 00-dinitrobenzidine (see above).

3. «^-Diamido-diphenyl, Diphenylin, is obtained, together with benzidine,
by the rearrangement of hydrobenzene or by the reduction of azobenzene with tin
and hydrochloric acid. It crystallizes in needles, melting at 45° and boils at 232°-
See Berichte, 22, 3011, for its derivatives.

2. Diannido-phenyl-tolyl, H2N.C,H^.CeH3(CH3).NH2(CH3:NH2 = 4=3),
o-Methyl Benzidine, is formed upon reducing a mixture of nitrobenzene and o-nitro-
toluene in alkaline solution. It melts at 115° and yields substantive dyestuffs
{Berichte, 23, 3222).

3. Diamido-ditolyls, Tolidines, H2N.CeH3(CH3).CeH3
(CH3).NH2. They are produced, like benzidine, by the alkaline
reduction of the three nitrotoluenes and further rearrangement of
the resulting hydrazotoluenes. In doing this the two benzene
rings, in o- and w?-tolidine (from o- and »«-nitrotoluene) unite at the
para-points, with reference to the amido-groups ; in the case of
/-tolidine (from/-nitrotoluene) they combine at the ortho-positions.
The first two contain the 2NH2-groups in para-positions relative to
the diphenyl union, hence yield substantive azo-dyes (see below)
(ssQ Berichte, 21,3145). The substituted Azohtments {Berichte,
23) 3265) deport themselves similarly.

0- Tolidine, from o-nitrotoluene (see above), crystallizes in leaflets with mother-
of-pearl lustre, and melting at 128° {Berichte, 21, 746, 1065). It is largely used
in the manufacture of substantive azo-dyes. See Berichte, 21, Ref. 874; 22,
2473 for the sulpho-acids of o-tolidine.

m-Tolidine, from ?«-nitrotoluene [Berichte, 22, 838), separates from its salts as
an oil, which gradually solidifies and melts at 109°.

p-Tolidine, from /-azotoluene [Berichte, 17, 472), forms delicate leaflets, melt-
ing at 103°.

Ditolylin, HjN.C^Hg.C^Hg.NHj (corresponding to diphenylin, see above),
is formed together with o-tolidine (see above), and does not yield substantive dyes
[Berichte, 23, 3253).

Analogous diamidodiphenyls have been prepared from nitroxylenes [Berichte,
21, 3147).

Benzidine Dyes.

By diazotizing benzidine (action of sodium nitrite (2 molecules)
and hydrochloric acid upon its salts, p. 629) we produce the salts

of tetrazb- or bis-diazodiphenyl, e. g., CuHs^^rVi (P- 639);

846 ORGANIC CHEMISTRY.

these combine with amines and phenols (amine sulpho-acids, phenol
sulpho-acids, oxycarboxylic acids, etc.) forming disazo-or tetrazo-
compounds (pp. 645-652). These azo dyes possess the remark-
able property of fixing themselves in the form of alkali salts upon
unmordanted plant fibres (P. Griess, 1879 j Berichte, 22, 2459).
They are called substantive dyes (cotton dyes), and are largely em-
ployed in dyeing. Diphenyl tetrazochloride and salicylic acid yield
a yellow dye, whose sodium salt, Ci2H8[N2.C6H3(OH).C02Na]2 is
chrysamine or flavophenirie (the first benzidine dye applied tech-
nically) {Berichte, 22, 2459). Diphenyl-tetrazo- chloride and
a-naphthylamine sulphonic acid (naphtionic acid) (2 molecules)
form a red dye ; its sodium salt is the technically important Congo
r,?^ (Bottger, 1884):—

N,.C,„H5(NH,).S0,Na
Ci,H8( , Congo Red.

AH the substantive dyestufiFs, similar to benzidine, yield diamido-dipbenyls and
analogous bodies, containing the two diamidogroups in the para position with
reference to the diphenyl union, e. g., orthotolidine (p. 845), diamidostilbene,
HjN.CsH^.CHiCH.CgHj.NHj {Berichte, 21, Ref. 383), dimethyl oxybenzidine
(p. 848); further, thiotoluidines (p. 684), thiobenzidine, etc. {Berichte, 20, Ref.
272). It may be said that as a rule those substituted benzidines (nitro and sulpho-
benzidines, tolidines, etc.) having the substitution in the meta-position (relative to the
amido-group) yield inactive, ox feeble substantive azo dyes. Diamidordiphenylene
oxide, benzidine sulphone (p. 845) and diamido carbazol (p. 847) constitute
exceptions. They contain a third ring-shaped chain (Berichte, 23, 3252, 3268).

The o-tolidine derivatives are also important from a practical standpoint. Thus,
o-tolidinetetrazochloride and a- and /3-naphthylamine sulphonic acids yield two
benzopurf urines, that form blue-tinted red ; a-naphthol-sulphonic acid forms the
red-tinted blue dye— azoWaf, Ci2Hi.(CHg)2[N2.Ci|,H5.(OHl.S03Na]2 {Berichte,
19, Ref. 422). Diniethoxyl-benzidine (dianisidine) (p. 836) and a-naphtholsul-
phonic acid form the blue benzazurine, stable on exposure to the light. More
recent dyes are sulphon-azurine, from benzidine sulphone (p. 845) {Berichte, 11,
2499), and various dyestuffs from diamido diphenylene oxide {p. 846) {Berichte,
23, Ref. 442).

For the preparation of these dye-substances add the aqueous solution of the
tetrazochloride to the aqueous solution of two molecules of the sodium salt of
the other component : —

q,H3(N,Cl)2 -f 2C,<,He(NH,)S03Na =

Ci,H8(N,.Ci„H5(NH,).S03NO), -j- 2HCI.

Sodium acetate, sodium carbonate or ammonia is added to the solution of the
sodium salt to combine the hydrochloric acid which is liberated. In all these
reactions the tetrazochloride first acts upon but one molecule of the amine or
phenol, forming an immediate product that dissolves with difficulty, as —

^i2"8^n!c1 + CioH5(NH,)S03Na

^8\N,.C,„H,(NH,).S03-f NaCl 4-HCl,

8\N,C1

c„h/N'"

OXY-DIPHENYL. 847

which immediately, in alkaline solution, attacks the second molecule of the amine
or phenol. If the intei mediate product be allowed to act upon a different amine
or phenol mixed tetrazodyes (see Berichte, 19, 1697, 1755 ; 21, Ref; 71) result.
Diphenyltetrazo-chloride, sulphanilic acid (l molecule) and phenol (i molecule)
yield a mixed dye of this description : —

Congo yellow = Q,H,/N.-C,H,.OH ^^^^^^_

Diphenylimide, Carbazol, C12H9N, is produced when the vapors of di-
phenylamine or aniline are conducted through a tube heated to redness : —

^NH = I J)NH -|- Hj ; also upon heating thiodiphenylamine (p. 604)

with reduced copper {Berichte, 20, 233).

It occurs in that portion of crude anthracene boiling at 320-360°, and is a by-
product in the manufacture of aniline. Carbazol dissolves in hot alcohol, ether
and benzene, crystallizes in colorless leailets, melts at 238° and distils at 351°.
Its concentrated sulphuric acid solution has a yellow color, and is colored a dark
green by oxidizing agents. The nitrogen atom of diphenylimide is inserted in the
two ortho-positions of the two benzene rings (relatively to the diphenyl union) ;
with two carbon atoms of each of these nuclei it forms a closed, Jive-membered
ring, such as is present in pyrrol and in indol {Berichte, 20, 234). This explains
the similarity of many reactions of carbazol with those of pyrrol and indol {Be-
richte, 21, 3299). Thus, it gives the pine shaving reaction, the dark blue colora-
tion with sulphuric acid and isatin, and forms with nitric acid a compound that crys-
tallizes in red needles, melting at 186°. Its acetate, CjjHjN.CjHjO, melts at 69°.
Its nitroso-derivative, Cj jH j.N.NO, consists of long, golden yellow needles, melt-
ing at 82°. A dye, analogous to diphenylamine blue, is produced upon heating
together carbazol and oxalic acid {Berichte, 20, 1904). //-Dianjido-carbazol,
Cj3Hj(NHj)jN, is formed when wjOT-diamido-benzidine (p. 845) is heated to 180°
with hydrochloric acid. It forms needles with a silvery lustre. It chars above
200°. Its tetrazo-compounds form substantive dyes {Berichte, 23, 3267). See
Berichte, 22, 2185 for tetra hydro-carbazol, CjjHijN. Phenyl-naphthyl caxha.-

20I, CigHj-N^ <[--,* Tx \nH, is perfectly analogous to carbazol. It is found

in the anthracene residues, and is prepared artificially from ;3-phenylnaphthyl-
amine, Ci-Hg.NH.CjHj. It is greenish-yellow in color and melts at 330°.

Azo-diphenylene, { /-'tt* ^Nj, is produced when the calcium azobenzoates

(ortho-, meta-, para) are distilled. It sublimes in yellow needles, melting at
170°.

We obtain a mono- and a di-sulphonic acid, CijHg.SOjH, and C]2Hj(S03H)2,
on digesting diphenyl with sulphuric acid. The first is formed with a very little
sulphuric acid. The disulpho-acid (di-para) crystallizes in deliquescent prisms,
melting at 72.5°. The oxy-diphenyls are the products on fusion with alkalies.

Oxy-diphenyl, CijHg.OH, Diphenylol, is obtained by diazotizing amido-
diphenyl sulphate. It sublimes in shining leaflets, melting at 165°. It boils at
305-308°. It dissolves with a beautiful green color in concentrated sulphuric acid.

848 ORGANIC CHEMISTRY.

Dioxydiphenyls, Diphenoh, Ci2Hg(OH)2. The di-para-compound, C5Hj(OH).
CgHj(0H)(7), is obtained from benzidine by means of the diazo-compound and
by fusing diphenyl-disulphonic acid with caustic alkali. It consists of shining
leaflets or needles, melting at 272° and boiling above 360°. /o-Diphenol (S),
formed on fusing ptienol-ortho- and para-sulphonic acids with potassium hydrox-
ide, and from diphenylin, through the diazo-componnd, melts at 161°. Two
additional diphenols (a and j3) are obtained when phenol is fused with caustic
potash; the a-melts at 123° and the ^- at 190°.

Oxydiphenyl-amido-derivatives can be produced by nitrating and reducing the
oxydiphenyls (JBerichte, 21, 3331 ; 22, 335), or from the oxyazobenzenes by the
molecular rearrangement of the hydrazc-compounds formed at first {Berichte, 23,
3256):—

C5H5.N:N.C8H,.O.CH3 yields HjN.C5H4.CsH3(O.CH3).NH3.

The arrangement does not occur unless a para position of the benzene nuclei is
unoccupied [Berichte, 23, 3256). Various diamido diphenol ethers (e.g., di-
methoxyl-benzidine from nitranisol) form blue dyestuffs, X\Vs benzoazurine (p. 846)
{Berichte, 21, Ref. 872) with naphthol sulphonic acid.

Diphenylene Oxide, Cy^f> = | ">0, results when phenylphosphate is

CgHj
distilled with lime, or from calcium phenylate or phenol and lead oxide under
the same treatment. It crystallizes in leaflets melting at 81° and distilling at
287°. CeH^.

Diphenylene Sulphide, | _)S, is produced when phenyl sulphide and

phenyl disulphide (p. 672) are distilled through an ignited tube. Shining needles
or leaflets, melting at 97° and distilling at 332°. Chromic acid oxidizes it to di-
phenylene sulphone, CijHgiSOj.

Coeroulignone or Cedriret, CieHieOs, is a derivative of hexa-
oxydiphenyl: —

*^,y2' ,, , •- y^^h Hexa-oxy-diphenyl.

Coeroulignone. Hydrocoeroulignone.

Coeroulignone separates as a violet powder when crude wood-spirit is purified
on a large scale by means of potassium chromate. It is further formed on oxidiz-
ing dimethyl-pyrogallol (p. 695) with potassium chromate or ferric chloride : —

H {(OCH,), vield^l^'Io'

^„ C,H, fCp.CH,),

2C„ _

UO.CH3),

Coerulignone is insoluble in the ordinary solvents, and is precipitated in fine,
steel-blue needles, from its phenol solution, by alcohol or ether. It dissolves in
concentrated sulphuric acid with a beautiful blue color, resembling that of the
corn-flower. Large quantities of water color the solution red at first. Reducing
agents (tin and hydrochloric acid) convert coeroulignone into colorless hydro-
coeroulignone, which changes again to the first by oxidation. Coeroulignone is,
therefore, a quinone body, deports itself towards hydrocoeroulignone like quinone
to hydroquinone, and hence may be called a double-nuclei quinone (p. 698).

DIPHENYL-DICARBOXYLIC ACIDS. 849

Hydrocoeroulignone, CjjHjgOg, crystallizes from alcohol and glacial acetic
acid in colorless leaflets, melting at 190°, and distils with almost no decomposi-
tion. It is a divalent phenol. When heated with concentrated hydrochloric or
hydriodic acid it breaks up into methyl chloride and Hexaoxydiphenyl,

CiaH^ljoH)^^''* + 4HCI = Ci,H,(OH), + 4CH3CI.

The latter crystallizes from water in silvery leaflets. It dissolves with a beautiful
bluish-violet color in potassium hydroxide. Acetyl chloride converts it into an
hexacetate. Diphenyl results when it is heated with zinc dust.

If potassium diphenyl-mono-sulphonate and disulphonate be distilled with potas-
sium cyanide the nitriles, CijH9.CN and CjjHg(CN)2, result; the former melts at
85°, the latter at 234°. The corresponding dipiienyl-carboxylic acids are obtained
when these are saponified with alcoholic potassium hydroxide or with hydrochloric
acid.

Diphenyl-carboxylic Acids, CuHi^Oj = CjHj.CjH^.CO^H. The three pos-
sible isomerides are known.

The ortho-B.ciA, d-phenyl-benzoic acid, is produced by fusing diphenylene
ketone (p. 851) with caustic potash. It dissolves with diSiculty in hot water and
melts at I n °. Diphenylene is reformed when it is distilled with lime. It sustains
a similar change upon being heated with sulphuric acid to 100° (Berichte, 20,
847) :-

CgH^.COjH CgH4

[ = I >CO + H,0.

If its sodium salt be heated with POCI3, the product will be diphenylene keton-
oxide (p. 860). The OTi?.'a-acid is formed by oxidizing isodiphenylbenzene and
melts at 161°. The para- is formed from diphenyl cyanide and when /-diphenyl
benzene (p. 852) is oxidized with CrOg and glacial acetic acid or phenyl tolyl
with nitric acid. It crystallizes from alcohol in bundles of grouped needles,
melting at 218°. It affords diphenyl on distillation with lime, and yields tere-
phthalic acid if oxidized with a chromic acid mixture.

Diphenyl-dicarboxylic Acids, C.^H, jO^ ^ Ci2Hj(C02H)2.

CeH^.CO.H

(i) The orthoaaA, Diphenic Acid, | {Berichte, 20, 847), is pro-

C^H,.CO,H
duced when phenanthrene or phenanthraquinone are oxidized with a chromic acid
mixture ; from the latter also by the action of an alcoholic potassium hydroxide solu-
tion. It is very readily soluble in hot water, alcohol and ether, crystallizes in shining
needles or leaflets, melting at 229°, and sublimes. Its barium and calcium salts
are readily soluble in water. The dimethyl ester melts at 73° ; the diethyl ester at
42°. Chromic acid changes diphenic acid to carbon dioxide. It yields diphenyl
when distilled with soda-lime; heated with lime it forms diphenylene ke-
tone. When diphenic acid is digested with acetic anhydride, its anhydride,
Ci2H5(CO)20, is formed. This melts at 213-217°, and when heated to 120°
with concentrated sulphuric acid decomposes into carbon dioxide and diphenylene
ketone carboxylic acid (p. 852) (Berichte, 21, Ref. 726).

The nitration of diphenic acid produces two dinitro-diphenic acids, CjjH5(N02)2
(COjH)^, a and /3, which are also formed in the oxidation of dinitro phenanthra-

71

850 ORGANIC CHEMISTRY.

quinone. The reduction of the a-acid (melting at 253°) with tin and hydrocUoric
acid yields diamido-diphenic acid, Q^^ ^^{^Yi ^ ^(<ZO ^) ,,, which may also be
obtained through the molecular transposition of meta hydrazo-benzoic acid (p. 751).
Distilled with baryta or lime it yields benzidine (together with diamido-fluorene).
The elimination of the NHj group causes it to change to diphenic acid. We,
therefore, infer that the latter (and also Phenanthrene, see this) is a diortho-de-
rivative of diphenyl.

(2) Isodiphenyl Dicarboxylic Acid, C^YL^if.O^Yi).Q,^Yi.^{C0^1^), isodi-
phenic acid (ortho-meta), may be prepared by fusing a-diphenylene-ketone car-
boxylic acid with caustic potash. It dissolves with difficulty in water and melts at
216°. Chromic acid oxidizes it to isophthalic acid. It yields diphenylene ketone
when distilled with lime.

(3) ^/ Diphenyl-dicarboxylic Acid is obtained from diphenyl-dicyanide,
and by oxidizing ditolyl with chromic acid in a glacial acetic acid solution. It is an
amorphous white powder, insoluble in alcohol and ether. It decomposes at higher
temperatures without first fusing. Heated with lime it affords diphenyl.

(4) (^-Diphenyl Dicarboxylic Acid may be obtained from diphenylene by
replacing its amido-groups with CN and then saponifying. White crystalline
leaflets, melting at 231° [Berichie, 22, 3019).

We also have a series of compounds, the diphenylene derivatives, in which 2
hydrogen atoms of the diphenyl group (both in the ortho-position with reference
to the point of union of the diphenyl group), are replaced by one carbon atom.
The following bodies are classed here : —

^6^4. C5H4. CgH^,

i )ch2 i )ch.oh i )ch.co,h

c,h/ c,h,/ c,h/

Diphenylene Fluorene Diphenylene

Methane. Alcohol. Acetic Acid.

I \C(0H).C02H

Diphenylene Glycollic Acid.

Carbazol, diphenylene oxide (p. 847) and diphenylene sulphide, are such di-
phenylene-diortho-derivatives. Intimately related to the diphenylene derivatives,
eg;

they are frequently derived from the latter on heating, by an orlho-condensation of
the two phenyl groups with the exit of two hydrogen atoms. Diphenic acid,
phenamthraquinone and anthraquinone are intimately related to them : —

CeH^.COjH CjH^.CO .CO.

I I I CeH / )C,H,.

CeH^.COjH CjH^.CO ^CO-^

Diphenic Acid. Phenanthraquinone. Anthraquinone.

Diphenylene Methane, CjjHjj = | yCYi^, Fluorene, occurs in coal

r H /
tar (boiling at 300-305°) and is obtained by conducting diphenylmethane,
(CeH5)2CH2, through an ignited tube, also on heating diphenylene ketone

FLUORENIC ACID. 85 1

with zinc dust, or with hydriodic acid and phosphorus to 160°. (For the detec-
tion of fluorene in presence of phenanthrene and anthracene see Berichte, 11,
203).

It crystallizes from hot alcohol in colorless leaflets with a violet fluorescence,
melts at 113°, and boils at 295°. It forms a compound with picric acid, which
crystallizes in red needles, melting at 80-82°. The chromic acid mixture oxidizes
it to diphenylene ketone. Fusion with caustic potash produces dioxydiphenyl.

Fluorene Alcohol, I ;CH.OH, results in the action of sodium amalgam

upon the alcoholic solution of diphenylene ketone and by heating sodium di-
phenylene glycoUic acid to 120°. It crystallizes from hot water in fine needles,
from alcohol in six-sided plates, melting at 153°. Chromic acid changes' it back
to diphenylene ketone. Concentrated sulphuric acid or PjOj colors it an intense
blue, and producesy?«»r?»« ether, (Ci3Hg)jO, melting at 290°.

Diphenylene Ketone, CijHgO = I >C0, is obtained from diphenic acid,

.... C,H,/

isodiphenic acid or o-phenylbenzoic acid when heated with lime and by oxidizing
diphenylene-methane with a chromic acid mixture, and by heating anthraquinone
and phenanthraquinone with caustic lime [Annalen, 196, 45). It is very soluble
in alcohol and ether, crystallizes in large yellow prisms, melting at 84°, and boil-
ing at 337°- Being a ketone it unites with hydroxylamine to produce an acetoxime,
melting at 192°. Potassium permanganate oxidizes it to phthalic acid. It is con-
verted into o-phenyl benzoic acid, on fusion with potassium hydroxide.

Diphenylene Glycollic Acid, I 3;C(OH).C02H, is produced when

phenanthraquinone is boiled with sodium hydroxide : —

CgH^ — CO CgH^.

I I +H,Q= I )C(OH).CO,H;

C,H,-CO C.-S./

in this instance an atomic rearrangement occurs, similar to that observed in the
transition of benzil to benzilic acid. It crystallizes from hot water in shining
leaflets, melting at 162°. It dissolves with an indigo blue color in concentrated
sulphuric acid ; this color disappears on the addition of water. Carbon dioxide
and watfer split off aaijluorene ether results. This is also produced by heating
the acid above its melting point. Chromic acid oxidizes it to diphenylene ketone.
If the acid be heated to 120° with HI and P it becomes,

Diphenylene Acetic Acid, I ^CH.CO.H, — Fluorene Carboxylic Acid.

This is insoluble in water, forms indistinct crystals, and melts about 221°. Its
ethyl ester melts at 165°. When heated above its melting point, more readily
with soda-lime, it is decomposed into carbon dioxide and diphenylene methane.

a-Fluorenic Acid, | ^C

CjHg/

^COjH
upon a-diphenylene-ketone carboxylic acid. It is almost entirely insoluble in water,
and melts at 245°. It yields fluorene when distilled with lime. Potassium per-
manganate reproduces diphenylene-ketone carboxylic acid.

852 ORGANIC CHEMISTRY.

CgH^v
Diphenylene-ketone Carboxylic Acids,Ci4H803= I ^CO. The a-acid

is produced by the oxidation of fluoranthene with a chromic acid mixture. It
crystallizes in red needles, melting at 191°- Sodium amalgam converts it into
fluorenic acid. Isodiphenic acid results when it is fused with potassium hydroxide
(p. 850), while heating with lime breaks it down into carbon dioxide and diphenylene
ketone ; fluorene is produced if it be distilled with zinc dust.

The p-acid is formed upon heating silver diphenylene-ketone dicarboxylate.
Yellow needles that sublime without melting. They- or ortho-acid \s formed when
diphenic acid is heated to 110° with concentrated sulphuric acid. It crystallizes
from alcohol in yellow needles, melting at 223° (Berichte, 20, 846). Fusion with
caustic potash changes it to diphenic acid. Its oxime melts at 263° ; its hydra-
zone at 205° (Berichte, 22, Ref. 727). CjH^.

Diphenylene-ketone Dicarboxylic Acid, I ^CO, results when retene-

^(CO,H)„
quinone is oxidized with potassium permanganate. A sulphur-yellow, crystalline
powder, which does not melt, but above 270° breaks down into carbon dioxide and
/-diphenylene-ketone carboxylic acid. It yields diphenyl when distilled with lime.
Diphenylene-ketone is produced from the silver salt (^i?nV/4/ie, 18, 1751).

Diphenyl Benzene, CjgHj^ ^ CgH^Q^'jj 5^ Diplienyl Phenylene, is pro-
duced when sodium acts on a mixture of dibrombenzene, C^^^r^^^x, 4) and
CgHjBr, also on conducting a mixture of diphenyl and benzene through ignited
tubes. Isodiphenyl benzene also results in the latter case ; therefore, both are
produced in the preparation of diphenyl (Berichte, 11, 175S).

/-Diphenyl benzene is sparingly soluble in hot alcohol and ether, easily in benzene,
crystallizes in flat needles, melts at[205°, sublimes readily, and boils at 400°. Chromic
acid, in glacial acetic acid, oxidizes it to /diphenyl carboxylic acid (p. 849), and
then to terephthalic acid. Isomeric isodiphenyl benzene melts at 85°, and boils
about 360°. Chromic acid, in glacial acetic acid, oxidizes it to benzoic acid and
an isomeric wj-diphenyl carboxylic acid.

Triphenyl Benzene, CgH3(CgHg)3 (i, 3, 5), is formed from acetophenone,
CjH5.CO.CH3, when heated with PjOe, or by conducting hydrochloric acid gas
into it, when there occurs a condensation similar to that observed in the formation
of mesitylene from acetone, CHg.CO.CH3 (p. 566). It crystallizes from ether in
rhombic plates, melting at 169°, and distils above 360°. Chromic acid oxidizes
it, in acetic acid solution, to benzoic acid (Berichte, 23, 2533).

2,. Derivatives of benzene nuclei joined by one carbon atom.

I. DIPHENYL METHANE DERIVATIVES.

The compounds, having two benzene nuclei joined by one car-
bon atom, are obtained according to the following methods : —

I. Zinc dust is added to a mixture of benzyl chloride and ben-
zene, and heat applied. An energetic reaction ensues, hydrogen

DIPHENYL METHANE DERIVATIVES. 853

chloride escapes and diphenyl methane results (Zincke, Annalen,

159.367):—

C,H5.CH,.C1 + C^H, = CeH5.CH,.CeH5 + HCl.

Diphenylmethane.

Benzyl chloride reacts similarly upon toluene, xylene and other
hydrocarbons: —

C,H,.CH,C1 + CeH,.CH3 = CeH3.CH,.CeH,.CH3 + HCl;

Benzyl Toluene.

and upon phenols or their acid esters {Berichte, 14, 261) : —

CeH^.CHjCl + CjHs.OH = CsHs.CH^.CjH^.OH + HCl.

Aluminium chloride may be employed as a substitute for zinc dust
(P- 569)-

The tertiary anilines (compare p. 601) react similarily to the phenols on the
application of heat (even without zinc) ; thus from benzyl chloride and dimethyl
aniline we get the base, C5H5.CH2.C8H4N(CHj)2, dimethylamido-diphenylme-
thane.

2. The fatty aldehydes are mixed with benzene (toluene, naphtha-
lene, diphenyl, etc.) and concentrated sulphuric acid then added ;
water separates and two phenyls replace the aldehyde oxygen
(Baeyer, Berichte, 6, 221) : —

2C.H5 + COH.CH3 = S'Jfs^CH.CH. + H2O.

Aldehyde. Diphenyl Ethane.

The acetaldehyde is applied as paraldehyde, and it is necessary to employ
strongly cooled sulphuric acid. Methylene aldehyde is applied in the form of
methylal, CH2(O.CH3)2 (p. 301), or methyl diacetate: —

2CeH, + CH2(O.CH3)2 = {C,n;)^CS.^ + 2CH3.OH.
Methylal. Diphenylmethane.

The reaction proceeds with special ease on using anhydrous chloral (or with
mono-and dichlor-aldehyde) and chlorine substitution products result : —

2C3He + COH.CCI3 = (CeH,)^ CH.CCI3 + H^O.

Sodium amalgam causes the replacement of the halogens in these derivatives, and
we get the corresponding hydrocarbons.

The benzene hydrocarbons react with the aromatic alcohols just
as they do with the aldehydes : —

C.H^.CH^.OH + C^H, = C.Hj.CH^.CeH, + H^O.

Triphenyl methane, (C8H5)2CH.C6H5, is similarly formed from benz-
hydrol, (C6H5)2CH.OH. Triphenyl methane derivatives are the
chief products when benzaldehyde is used.

854 ORGANIC CHEMISTRY.

The benzenes also condense with ketones, aWehydic acids and ketonic acids.
Thus from benzene and glyoxylic acid we obtain diphenylacetic acid, with pyro-
racemic acid, a-diphenylpropionic acid. Sometimes we get an aldol condensation
with the production of oxy-compounds (p. 716) ; in this way dibrom-atrolactinic

acid, C8H5.C(OH):^pir^2, results from benzene and dibrom-pyro-racemic acid.

The aldehydes also act upon the phenols, yielding phenol-derivatives of the
diphenylmethanes; here it is better to substitute SnCI^ for sulphuric acid [Be-
richte, 11, 283). Thus we get diphenol ethane from paraldehyde and phenol : —

CH3.CHO + 2C6H5.OH = CH3.CH(C5H4.0H)2 + H2O.

Ethidene dinaphthyl ether, CHg.CH(O.CioH7)2 and \^&' condensation product,

CHj.Ch/^ioHs^O {Berichie, ig, 3004, 3318), are produced when acetalde-

hyde acts upon ;8-naphthol in the presence of glacial acetic acid and a little hy-
drochloric acid.

The tertiary anilines react like the phenols (p. 601) and amido-derivatives
result. Instead of the aldehydes (or their ethers) we can employ their haloids,
when the reaction will begin on the application of heat. For example,
from methylene iodide, CS.^^, and dimethyl aniline we obtain the base

CH /p«^*-^fpjj3)2 ; the same product results with CCI3H and CCl^. Ace-

tone and zinc chloride yield the base, {!^^^fi\^r^x:i^\z,r'\:i^\ {Berichte, 21,

Ref. 16). Such bases are also produced as byproducts in the manufacture of
methyl aniline and malachite green.

Benzaldehyde and the dimethyl anilines condense to amidobenzhydrols when
heated with concentrated hydrochloric acid, whereas triphenylmethane deriva-
tives result if zinc chloride, sulphuric acid and oxalic acid be used. Chloral reacts
similarly with dimethylanilines, accompanied by hydrol condensation (Berichte,
21, 3299).

If the hydrocarbons be oxidized with a chromic acid mixture
they yield ketones, and the group CH2 or CHR is converted into CO.
From dimethyl methane and dimethyl ethane we obtain diphenyl
ketone: —

^g}cH, and g«J^}cH.CH3 yield g^g^}cO.

Should alkyls be present in the benzene nucleus these are oxidized
to carboxyls : —

CeHs.CHj.CjH^.CHj yields CjHj.CO.CeH^.COjH.
Benzyl Toluene. Benzoyl Benzoic Acid.

Such ketones are further produced : —

I. If benzoic acid or its anhydride be heated with benzenes and P2O5 (Merz).
A condensation similar to that of the hydrocarbons takes place here : —

C^H CO.OH -f CjH, = CeH,.CO.CsH + H,0.
Benzoic Acid. Diphenyl Ketone.

DIPHENYL METHANE DERIVATIVES. 85 5

2. By the action of benzoyl chloride on benzenes, in the presence of aluminium
chloride (comp. p. 853) : —

C5H..COCI + CjHs.CH^ = CjHs.CO.CjH^.CH, + HCl.

Benzoyl Chloride. Toluene. Phenyl tolyl Ketone.

Phosgene reacts in the same manner, and acid chlorides are the first products
(comp. p. 739) :—

COCl, + aC^Hj = CeH5.CO.CeH5 + 2HCI.

3. According to the general method of producing ketones, on heating the cal-
cium salts with aromatic acids : —

CeHj CO,H + CeHj.CO.H = iC^-B,),CO + CO, + H,0,
Benzoic Acid. Benzoic Acid. Diphenyl Ketone.

CeH5.CO,H + CeH,{CHs^ = CeH,.(clS)^° + ^°^ + "^'^
Benzoic Acid. Toluic Acid. Phenyl-tolyl Ketone.

On heating with zinc dust or hydriodic acid and amorphous
phosphorus, the ketones sustain a reduction of the CO group and
revert to the hydrocarbons, for example, diphenyl ketone yields
diphenyl methane. Sodium amalgam changes them to secondary
alcohols: —

{C,U,),CO + H, ^ (CeH5),CH.OH.

Pinacones are simultaneously produced through the union of two
molecules (see benzpinacone).

The oxy-ketones and ketone phenols are produced from the phenols by the ac-
tion of benzoyl chloride, by heating with zinc chloride, or more readily with
aluminium chloride; further by heating benzo-trichloride, CgHj.CClj, with
phenols and zinc oxide: —

CeHj.COCl + CeHj.OH = CeH^.CO.CeH^.OH + HCl,
Benzoyl Phenol.
CjHs.CClj + CgHj.OH + ZnO = CgHs.CO.CgH^.OH + ZnClj + HCl.

The reaction is analogous to the action of chloroform upon phenols in alkaline
solution, when aldehyde phenols (oxy-aldehydes) are obtained (p. 723).

Instead of the free phenols it is better to use the benzoyl esters of the phenols
{e. g-., CjH^.O.CjHjO). The first products are the benzoyl esters of the phenol
ketones, ^. ^., CgHj.CO.CeH^.O.CjHsO, which yield the free phenol ketones
when saponified with alcohoUc potassium hydroxide {Berichie, 10, 1969). In the
use of tlie free phenols we get, on the contrary (especially with CjHj.CClj, even
by gentle digestion), dye Substances, which belong to the aurine series, and
are derived from triphenyl methane.

When benzoyl chloride and zinc chloride act on the divalent phenols (their
benzoyl esters) e. g., resorcin, we obtain their mono- and di-ketones {Berichte, 12,
661), as —

CeH,.C0.CeH3(0H), and %'^'^)C,^,{On),.

Zinc chloride converts salicylic acid, CeH^(OH).COjH, and phenol into salicyl-
phenol, CeH4(OH).CO.C5H4.0H {Berichte, 14, 656).

856 ORGANIC CHEMISTRY.

We can also derive the amido-ketones, e.g., CgHB.CO.CgH^.NHj, by methods
similar to those employed with the ketones and oxy-ketones : —
I. By heating benzoic acid with tertiary anilines and P2O5 : —
C.Hj.CO.OH + C,H5.N(CH3)2 = CeHj.CO.CeH^.NCCHa)^ + H^O,

whereas, by the action of benzoyl chloride two benzoyl groups enter the benzene
nucleus {Annalen, ao6, 88) ; 2. By the action of benzoyl chloride upon primary
anilines, in which both amide hydrogens are replaced by acid radicals (as in
phthalanile,CeH5.N(CO)2C5H4^ (p. 6u), on heating alone, or with zinc chloride
or aluminium chloride : —

CgHj.COCl + CeH5.N(C0.R)j = CjH5.CO.C(,H4.N(CO.R)2 + HCl.

The free amido-ketones are obtained by the saponification of these anilides
{^Berichte, 14, 1836).

Furthermore, ketonic acids and diketones are produced according to these
methods. For example, we obtain meta-benzoyl benzoic acid (its chloride) from
benzoyl chloride and benzoic anhydride, with zinc chloride (Berichte, 14, 647) : —

aCjHe.COCl + {C^Yl^.CO)^:) = aCjHs.CO.CjH^.COCl + H^O,

Benzoyl Benzoic Acid.

and meta benzoyl benzoic acid together with so-called isophthalphenone {Be-
richte, 13, 321 ; ig, 146) from isophthalic chloride and benzene by means of
AICI3 :—

'-6"4\C0.C1 (3) y*'*^^ ^6"4\C0.C1 ^"^ '"s^^XCO.CgHg'

tf-benzoylbenzoic acid is obtained from phthalic anhydride and benzene with
aluminum chloride. It is further converted into ff-diphenyl phthalide (p. 880).
The latter can be directly obtained from o-phthalyl chloride and benzene by means
of AlCl,.

Diphenyl Methane, QgHia = CeHj.CH^.CeHs, Benzyl ben-
zene, is obtained according to the synthetic methods already men-
tioned : from benzyl chloride and benzene with zinc dust or AICI3 ;
from formic aldehyde or benzyl alcohol and benzene with sulphuric
acid ; and from CHjClj (or CHCI3) with benzene and AICI3 (to-
gether with anthracene).

In the preparation of diphenyl methane, lo parts of benzyl chloride are
digested with 6 parts of benzene and zinc dust, etc. ; the latter only induces the
reaction and when this has commenced it can be filtered off {Annalen, 159, 374).
A better method is that of Friedel. It consists in digesting 10 parjs benzyl
chloride with 50 parts benzene and 3-4 parts of AICI3.

Diphenyl methane is easily soluble in alcohol and ether, possesses
the odor of oranges, crystallizes in needles, melts at 26.5°, and
boils at 262°. When conducted through ignited tubes it yields
diphenylene methane (p. 850) ; a chromic acid mixture oxidizes it
to diphenyl ketone.

DIPHENYL CARBINOL. 857

When treated with bromine in the heat it yields (C,H5)2CHBr, diphenyl-brom-
methane, and (CgH5)2CBr2 diphenyl dibrom-melhane ; the former melts at 45°,
and the latter is a brown crystalline mass.

Nitrodiphenyl Methane, C5H5.CHj.CjH4.NOj. The oriAo-compound is pre-
pared from o-nitrobenzyl chloride and benzene with AICI3. It is liquid and when
oxidized by chromic acid and acetic acid yields o-nitro-benzophenone. The meta-
and/a?-a-bodies are derived from meta- and para-nitro-benzyl alcohol (p. 709) by
means of benzene and sulphuric acid. The first is an oil; the second melts at 31°
{Berichte, 18, 2402).

Diphenyl methane dissolves in concentrated nitric acid yielding two diniiro-
derivatives, the a- melting at 183°, and the /3-variety at 118° (Berichte, 21, 1347;
23, 2578). Further nitration with nitric-sulphuric acid produces Tetranitro-
diphenyl Methane, [C5H3(NOj)2]2CH2; yellow prisms, melting at 172°. It
forms dark blue colored salts with alcoholic potash (p. 85i and Berichte, 22,
2445).

Diphenyldinitro Methane, (C5Hj)jC(N02)2, results from the action of NjO^
upon benzophenoxime (similar to the formation of pseudo-nitriles, p. «09). Color-
less leaflets, melting at 78° (Berichte, 23, 3491).

The reduction of the a-dinitro-prodnct yields a-Diamido-diphenyl methane,
(C8H4.NHj)jCHj (dipara); shining leaflets, melting at 85°. Its tetramethyl
derivative, \Q.^ ^^(Q.Vi ^^fiYi^, results from dimethyl aniline by means of
CjHjIj(CCl3H and CCl^), or with methylal (p. 853), and as a by-product in the
manufacture of malachite green. It crystallizes in shining leaves, melts at 90°,
and distils undecomposed. It yields a blue dyestufif by oxidation.

The hydrogen of the group CHj, attached to basic radicals is very readily
replaced by sulphur ; so that by heating with sulphur to 230° we obtain the thio-
compound, CS[C6H4.N(CH3)j] j. Benzylaniline, CeH5.CHj.NH.C5H5 [Annalen,
259, 300) reacts similarly.

^-Diamido-diphenyl Methane, (CgH4.NHi,)3CHj, from the ;3-dinitro-
compound, melts at 88°.

Oxy-diphenyl Methane, CgH^.CHj.CgH^.OH (psxa.-). Benzyl phenol, oh-
tained from benzyl chloride and phenol, melts at 84° and boils at 320°.

Dioxydiphenyl Methane, CHj(C5H4.0H)2 (dipara), is produced on fusing
diphenyl methane disulphonic acid with KOH. It crystallizes in shining leaflets
or needles, melts at 158° and sublimes. By stronger heating with caustic
potash (300°), it decomposes into para-oxybenzoic acid and phenol. Its dimethyl
ether, CH2(CeH4.0.CH3)2, is formed from anisol and methylal, and melts
at 52°.

Diphenyl Carbinol, (CgH5)2CH.OH, Benzhydrol, is produced on heating
diphenyl brom-methane, (CeH5)2CHBr, with water to 150°, more readily from
diphenyl ketone (CgHjjjCO, with sodium amalgam, or by heating with alco-
holic potassium hydroxide and. zinc dust (together with benzpinacone). It is
sparingly soluble in water, easily in alcohol and ether, ciystallizes in silky needles,
melts at 68°, and boils at 298° under partial decomposition into water, and benz-
hydrol ether, [(CgHsJj.CHJjO, melting at 109°-

The benzhydrol amide derivatives may be synthesized by the condensation of
benzaldehyde with dimethyl-anilines upon heating them with hydrochloric acid
(sulphuric acid, zinc chloride and oxalic acid produce triphenyl derivatives,
Berichte, 21, 3293) : —

C„H5.CHO -f C5H5.NR2 = C5H5.CH(OH).C5H4.NR2.

Dimethyl-amido-benzhydyol,

72

8c 8 ORGANIC CHEMISTRY.

M)«o-amido-derivatives, such as these, dissolve in acids, forming colorless or

slightly colored compounds. ,,„„^ „ tt -^T/z-tr \ u

lNitrodimethyl-amidobenzhydrol,NO,.C,H,.CH(OH).CeH^.N(CH3)„ results

in the condensation of/-nitrobenzaldehyde with dimethyl aniline on heating them
with hydrochloric acid. Yellow needles, melting at 96°. Zinc dust and hydro-
chloric acid reduce it to , . , tt i>t ^ -u r•t^/•r\t^^ r' tr
Unsymmetrical Dimethyldiamidobenzhydrol, HjN.LsH^.OtHunj.L-eti^.

N(CH3)„ melting at 165°. ^PH M^ C H \

Tetramethyl-diamidobetizhydrol, jcS^)^N.C,Ht/^"-°"' ^^' ^''° P''"
pared by reducing tetramethyldiamidobenzophenone (p. 859). Such diamido-
diphenylhydrol bases are colorless, but when t/i^ested with acids yield deep blue
colored salts, corresponding to the rosaniline salts {Berichte, 21, 3298) ; they very
probably are benzhydrol or carbinol salts : — •

■^S'^S'^'S*^CHCl-hydrochloride.

Perfectly analogous compounds are : —

ir^'^Mr^S^>CCl, and i3]^^.C,HAcg.
(CHji^N.C^H^/ 2 (CH3)2N.C.eH^/'

Tetramethyldiamido- Tetramethyldiamido-

benzophenone Chloride. thiobenzophenone.

they are derivatives of diamidobenzophenone, and have a salt-like character. The
first is dark-blue in color, while the second is a crystalline powder, showing a
cantharides-green color. Its solutions are green or dark red in color (Berichte,
20, 1732).

Benzophenone, Diphenyl Ketone, (C6H5)2CO, is obtained
according to the general methods and by heating mercury phenyl,
(CeHj)^ Hg, with benzoyl chloride. It is prepared (along with
benzene) on distilling calcium benzoate, or from benzoyl chloride
and benzene with AlClj ; most easily by adding AICI3 to the solu-
tion of COCI2 in benzene {^Berichte, 10, 1854). It is dimorphous;
generally crystallizes in large rhombic prisms, melting at 48-49°,
sometimes in rhombohedra, which melt at 27° and gradually change
to the first modification. It has an aromatic odor, and boils at
295°. When fused with alkalies it decomposes into benzoic acid
and benzene; if it be heated with zinc dust diphenyl methane is
produced.

PCI5 converts it into the chloride (C5H5)j,CCl2. A liquid, boiling at 220°.
Hot water changes it to benzophenone. Hydroxylamine converts benzophenone
into

Benzophenoxime, (C5H5)2C:N.OH, crystallizing in needles, melting at 140°
[Berichfe, ig, 989). An isomeric benzophenoxime could not be obtained, while
unsymmetrical benzophenones, e. g., brombenzophenone and phenylethyl ketone,
each form two oximes (pp. 727, 718).

Benzophenoxime (like other ketone oximes, p. 727), when digested at 100° with
sulphuric acid, with hydrochloric acid and acetic acid, etc., sustains the following
peculiar molecular rearrangement [Berichte, 22, Ref. 591) : —

C,H5,C(N.OH).CeH5 ^C.H^.CO.NH.CeH^, Benzanilide.

THIOBKNZOPHENONE. 859

Tlie isomeric benzanilide imide-chloride is produced in like manner from the imide
chloride formed by PCI5 (p. 744). Phenylhydrazine and benzophenone unite
when their alcoholic solution is warmed, forming the pkenylhydrazone, {f^^^^-i,
CN^H.CgHj, crystallizing in delicate needles, melting at 137° [Berickie, 19,
Ref. 302).

Nitrobenzophenones, CeH5.CO.C|.H^(NOj). The three isomerides are pro-
duced by the oxidation of the three nitrodiphenyl-methanes (p. 857). The meta
compound has also been obtained from zw-nitrobenzoyl chloride with benzene and
AICI3. It melts at 94° (Berickte, 18, 2401).

Dinitrobenzophenones, CgHj(N02).CO.CjH4(N05,). The a-body is pro-
duced by oxidizing a-dinitro-diphenylmethane. It melts at 190°- The /3- and y-
bodies are formed by the nitration of benzophenone with fuming nitric acid. The
former melts at 190°; the latter at 149°.

Amidobenzophenones, C8H5.CO.CjHj(NH2), Benzoanilines. The three
isomerides are produced by the reduction of the three nitrobenzophenones with
tin and hydrochloric acid. The ortho melts at 106°, and condenses with acetone,
by the action of caustic soda (same as o-amido benzaldehyde, p. 720), forming
7-phenyl-a-methylquinoline [Berickte, 18, 2405) :—

^NHj ^N C.CH3

j^/^/n-amidobenzophenone melts at 87°. The/a:r« compound is produced when
benzanilide or phthalanile is heated with benzoyl chloride and zinc chloride ; the
anilides formed at first being saponified (p. 858). Colorless needles or leaflets,
melting at 124° {Berickte, 18, 2404).

Upon methylaling/* amidobenzophenone we obtain Dimethyl/ amidobenzo-
phenone, C5H5.CO.CjH^.N(CH3)2. It can also be prepared by the decomposi-
tion of malachite green with hydrochloric acid [Berickte, 21, 3293).

Diamidobenzophenones are formed by reducing dinitrobenzophenones, and
by the decomposition of the rosanilin^s.

a-Diamidobenzophenone, CO(C5H^.NH2)2, is produced from a-dinitroben-
zophenone and by the breaking down of pararosaniline. It consists of large
plates, melting at 237° and forjjis substantive tetrazo dyestuffs (Berickte, 22, 988).

Tetramethyl-dianiidobenzophehone, CO (^ p.* pj*' jj>(-. jj^K results upon

heating hexamethyl violet with hydrochloric acid [Berickte, 19, 109). It is
technically prepared by the action of COClj upon dimethyl aniline in the presence
of AlCl,, and serves for the production of hexamethyl violet. From alcohol it
crystallizes in yellow leaflets, melting at 173° [Berickte, 22, 1876). Being a
ketone it unites with hydroxylamine and phenylhydrazine [Berickte, 20, I III).
Dimethylaniline (and PCI3) converts it into methyl violet, while it yields Victoria
blue (p. 876) with phenylnaphthylamine, Ci„H,.NH.CjH5.

When heated with ammonium chloride and zinc chloride a base is produced,
the salts of which have a beautiful yellow color. The hydrochloride,

/^ri''^^i?/?''H >C:NH.HC1, crystallizing in golden yellow leaflets, is aiaramine,

important as a cotton dye. Cotton mordanted with tannin is colored a beautiful
yellow by this salt. Perfectly analogous dyestuffs are obtained from the primary
anilines and diamines [Berickte, 20, 2844).

Thiobenzophenone, (CgHsJ^CS, is derived from benzene by means of
CSCI2 and AlCl,. It is a reddish-brown oil. Hydroxylamine converts it into
benzophenoxime,' and with hydroxylamine it yields a hydrazone [Berickte, 21, 341).

86o ORGANIC CHEMISTRY.

The Thiobenzophenone (melting at 146°), derived from benzophenone chlor-
imide and potassium sulphide, appears to be a polymeride.

Tetramethyldiamido-thiobenzophenone,CS[CgHj.N(CH3)2]2, results from
the action of hydrogen sulphide or carbon disulphide upon the auramines; the
imide group is displaced. It is technically prepared from dimethylaniline and
CSCI2 {Berichte, 20, 1731 and 2857). It consists of ruby-red crystalline leaflets
or a cantharides-green crystalline powder, melting at 162° (202°). In transmitted
light its benzene and carbon disulphide solutions show a red color, while they are
green in reflected light. When boiled with hydrochloric acid hydrogen sulphide
splits off and tetramethyldiamido-benzophenone results.

Oxybenzophenones, C5H5.CO.CgH4(OH), Benzoyl Phenols. The /ara is
obtained from /i-amidobenzophenone with nitrous acid {^Berichte, 18, 2404) and
from phenol with benzoyl chloride or C5H5.CCI3 (p. 854). It is soluble in hot
water. It melts at 134°, and when fused with caustic potash decomposes into
benzene and para-oxybenzoic acid.

Dioxybenzophenones, C0(CjH^.0H)2. The dipara is obtained from dioxy-
diphenyl methane by oxidizing the dibenzoyl ester with chromic acid in glacial
acetic acid and saponifying with alkahes; also by the decomposition of aurine,
benzaurine, phenolphtalein, and rosaniline (^Berichte, 16, 1931) on heating with
water or caustic alkali. It crystallizes from hot water in needles or leaflets, melts
at 210°, and decomposes on fusion with caustic potash into para oxy-benzoic acid
and phenol. It yields an acetoxime with hydroxylamine.

The flTj'oT-Mo-compound is formed by fusing diphenylene ketone with caustic
potash {Berichte, 19, 2609). It separates in the form of an oil, that solidifies
with difficulty. It boils about 330-340°. It combines with hydroxylamine and
phenylhydrazine. Stronger fusion with caustic potash resolves it into phenol and
salicylic acid. The anhydride of diortho-dioxybenzophenone is Diphenylene

Ketone Oxide, Q.O'(^^^^0,or Cfi.^(^^Q^Yi.^, Xanthone, produced

from salicylic phenyl ether or phenylsalicylic acid by the action of concentrated
sulphuric acid {Berichte, 21, 502). It is volatile with steam, crystallizes in yellow
needles, melting at 174°, and boiling at 250°. It is rather singular that it does
not unite with hydroxylamine or phenylhydrazine. When reduced with HI it
affords methylene diphenyl oxide, CYi.^(Cl,^^.fi. White leaflets, melting at 99°
and boiling at 312°. It forms dioxy-benzophenone on fusion with KOH.

Dioxydiphenylene-Ketone Oxide, CisH804= HO.CsH3/^')CeH3.0H,

Euxanthone, occurs together with euxanthinic acid in Indian yellow (jaune
indien). The latter is resolved into glycuronic acid (p. 491) and euxanthone when
heated with dilute sulphuric acid. It has been synthetically produced by the
action of acetic anhydride upon /3-resorcylic acid and hydroquinone carboxylic
acid {Berichte, 23, 13 ; Annalen, 254, 265). It crystallizes in yellow needles or
leaves, melting at 237°, and then subliming. It is reduced to methylenedipheny-
lene oxide by distillation with zinc dust.

Trioxybenzophenone, €5112(011)3.00.05115, is formed by fusing pyrogallol
and benzoic acid with zinc chloride at 145°. It crystallizes in yellow needles with
one molecule of water, and melts at 138°. It forms orange yellow dyestuffs with
mordants. Many other pojyoxybenzophenones have been obtained by analogous
methods {Berichte, 23, Ref. 43).

BI-DINITRO-DIPHENYL ACETIC ACID. 86l

Diphenyl Ethane, Cj^Hi^ = (C|5H5)2CH.CH3 (isomeric with dibenzyl), is
obtained from benzene and paraldehyde with sulphuric acid, from /3-bromethyl
benzene, CgH5.CHBr.CH3, and benzene with zinc dust, from benzene and
CH3.CHCI2 with AlCl,. It is a liquid, boiling at 268-271°, and in the cold
becomes a crystalline solid. Chromic acid oxidizes it to benzophenone. Nitric
acid does not oxidize its side chains (Berichte, 17, Kef. 674). Diphenyl
trichlorethane, (CsH5)jCH.CCl3, formed from benzene and chloral, consists of
leaflets, melting at 64°. Alkalies convert it into diphenyldichlor-ethylene, melting
at 80° and boiling at 316° {Berichte, 22, 760). Diphenyliribromeihane melts at
89°. Sodium amalgam reduces both to diphenyl ethane.

Mono-chlor-aldehyde (mono-chlor-acetal or dichlorelher) and benzene yield
Diphenyl mono-chlor-ethane, (CgH5)2CH.CH2Cl, a thick oil, which on boil-
ing is converted into

Diphenyl Ethylene, Ci^Hj^ = (CgH5)2C:CH2. This is isomeric with
stilbene, is also formed from a dibrom-ethylene, CHgrCBr^, by means of benzene
and AICI3, and is an oil, boiling at 277°. Chromic acid oxidizes it to diphenyl
ketone.

Perfectly analogous, unsaturated hydrocarbons are also obtained from toluene,
xylene, naphthalene, etc. If diphenyl monochlorethane (or its analogues) be
heated alone hydrochloric acid is withdrawn, and there results, not diphenyl
ethylene, but, by molecular transposition, isomeric stilbene (and its analogues) : —

(C,H5),CH.CH,C1 = C,H5.CH:CH.C,H5 + HCl.

Stilbene,

Diphenylacetaldehyde, (CgH5)2.CH.CHO, is produced by the action of
sulphuric acid upon hydrobenzoin (Berichte, 22, Ref. 10).

Diphenylaceto-nitrile, (CgH5)2CH.CN,results when diphenylbrommethane is
heated with Hg(CN)2 to 165°, or is obtained from diphenylacetic acid through the
amide (^Berichte, 2a, Ref. 198). Crystallized from ether it forms brilliant prisms,
melting at 72° and boiling about 184° (at 12 mm). The hydrogen of its CH-
group is readily replaced by alkyls. Iodine, acting upon its sodium derivatives,
produces tetraphenylsuccino-nitrile, (CgH5)4C2(CN)2 [Berichte, 22, 1227).

Diphenyl Acetic Acid, Cj^Hj^O^ = (C8H5)2CH.C02H, is formed : by the
action of zinc dust on a mixture of phenyl-bromacetic acid (p. 754) and benzene :

CeH-.CHBr.CO2H H- C^Hg^ ^^HsXcH.COaH + HBr;

from diphenyl brom-methane, (CgH5)2CHBr, by means of the cyanide; and by
heating benzilic acid to 150° with hydriodic acid. The acid crystallizes from water
in needles, from alcohol in leaflets, melting at 146°. When oxidized with a chromic
acid mixture it yields benzophenone ; and when heated with soda lime we get di-
phenyl methane. Its ethyl ester melts at 58°; the methyl ester at 60° [Berichte,
21, 1318).

Bi-dinitro-diphenyl Acetic Acid,,,^TT3;^f^2i2>CH.C02H.

The ethyl ester is derived from dinitro- phenyl acetoacetic ester and dinitro-
phenyl-malonic ester (pp. 764, 791) by the action of ff/-dinitrobrombenzene; the
group, CO.CH3 (andCOj.CjHj) being replaced. It may be similarly prepared from
dinitro-phenyl-acetic ester (p. 754) {Berichte, 21, 2470). It dissolves with diffi-
culty in alcohol and ether, and crystallizes from alcohol in colorless prisms, melting
at 154°. Alcoholic potash or soda converts the ester, by the substitution of the hy-
drogen of the CH-group, into brilliant metallic salts, dissolving in alcohol and
water, with a dark blue color. All methane derivatives react in like manner, pro-
vided they contain two or three nitrophenylene groups, e. g., bi-dinitro-phenyl-

862 ORGANIC CHEMISTRY.

methane, [C5H3N02)2]2CH2 (p. 857) and ternitrophenyl methane (CgH^^NOj,),
CH (p. 866) {Berickte, 22, 2476).

Diphenyl GlycoUic Acid, Benzilic Acid, (CsH5)2C(OH).C02H, is produced
by a molecular rearrangement of benzil (see this) when digested with alcoholic
potassium hydroxide, and from diphenyl acetic acid by the action of bromine vapor
and boiling with water. We can prepare it by fusing benzil with caustic potash
[Berickte, 14, 326) ; or better by the action of aqueous potash and air upon ben-
zoin [Berickte, 19, 1868). Anisilic, cuminilic and dibenzyl glycoUic (see benzoin
group) acids are perfect analogues of benzilic acid.

Benzilic acid is very readily soluble in hot water and alcohol, crystallizes in
needles and prisms, melts at 159°, and is of a deep red color. It dissolves with a
dark red color in sulphuric acid. It yields diphenyl acetic acid when heated with
hydriodic acid : on distilling its barium salt it breaks up into carbon dioxide and
benzyhydrol ; oxidation yields benzophenone. For the derivatives of benzilic acid,
see Berickte, 22, 1213, IS37-

Benzyl Toluenes, Phenyl tolyl methanes, CuHu = C6H5.CH2.
CjHi. CHs. A liquid mixture of ortho- and para-benzyl toluene,
which cannot be separated, is obtained by the action of zinc dust
on a mixture of benzyl chloride and toluene ; by heating benzyl
chloride to 190° with water, or toluene to 250° with iodine. The
pure para-hoAy has been formed by heating para-phenyl tolyl ke-
tone with zinc dust, and is a liquid, boiling at 285°-

When it is oxidized with a chromic acid mixture we get the cor-
responding phenyl tolyl ketones and benzoyl benzoic acids.

Phenyl-tolyl Ketones, Ci^Hi^O = CgHj.CQ.CjH^.CHa. A mixture of
the ortho- and para-compounds is obtained when benzoyl chloride and toluene
are heatedwith zinc dust (in small quantity), by the distillation of a mixture of
calcium benzoate and para toluate, or by heating benzoic acid and toluene with
PjOj. The product is an oil, from which the para-body may be crystallized out
by cooling, while the ortho-derivative remains liquid.

The para compound is dimorphous, crystallizing in hexagonal prisms, melting
at 55°, and in monoclinic prisms, melting at 58-59°. The latter modification is
the more stable. It boils at 310-312°, and is sparingly soluble in alcohol. When
heated with soda lime it decomposes into benzene and paratoluic acid ; chromic
acid converts it into parabenzoyl benzoic acid. Sodium amalgam transforms para-

ketone into phenyl paratolyl carbinol,p„= ^CH.OH, consisting of shining
needles, melting at 52°. *^v"-?/

Phenyl-ortho-tolyl Ketone is a liquid and boils about 316°.

A characteristic feature is the ability of the ortho-, but not the
para-derivatives, to change readily to anthracene and its derivatives,
in consequence of an ortho-condensation of the two benzene nuclei
(p. 850). Thus anthracene is produced on conducting phenyl-
tolyl methane through an ignited tube or upon heating the ketone
with zinc dust, and we obtain anthraquinone (see anthracene) on
heating ortho-phenyl-tolyl-ketone with lead oxide.

Other diphenyl ketones, containing a methyl group in the ortho
position, relatively to the ketone group, are prepared in a similar
manner, see Berickte, 18, 1797.

BENZOYL BENZOIC ACIDS. 863

Benzoyl Benzoic Acids, CuHioO^ = C5H5. CO. CsHi.COaH,
result from the oxidation of the phenyl tolyl methanes or phenyl-
tolyl ketones, and can be synthesized by the methods given upon
p. 856.

The para-acid crystallizes and sublimes in leaflets, melting at
194°. The w^/a-acid, from isophthalic chloride and benzene, con-
sists of needles, melting at 161°. The orfko-acid is most readily
obtained from phthalic anhydride, benzene and AICI3 (p. 856): —

It crystallizes with i molecule of HjO, which is lost at 110°, and
it then melts at 127°. Heated to 180° with phosphorus pentoxide,
water is eliminated, and anthraquinone is produced ; in the same
manner we get anthraquinone sulphonic acid by digestion with
fuming sulphuric acid. Anthracene is produced when it is heated
with zinc dust. With benzene and aluminium chloride orthoben-
zoyl-benzoic acid yields phthalophenone, with phenol and stannic
chloride oxyphthalophenone (see phthaleins).

If tin and hydrochloric acid or sodium amalgam be allowed to act on the
alcoholic solution of the para-acid we obtain Para-benzhydryl-benzoic Acid,
CjH5.CH(OH).C6H4^.C02H, melting at 165°, and passing back into benzoyl
benzoic acid when oxidized. Heated to i6o° with hydriodic acid, it yields ben-
zyl benzoic acid, CgHj.CHj.CgH^.COjH, which is also produced in small
quantity from benzyl toluene by oxidation with nitric acid. This melts at 157°,
and is rather readily soluble in hot water. Chromic acid oxidizes it to benzoyl
benzoic acid. Diphenyl methane is produced on heating it with soda-lime.

In the same manner ortho- benzoyl benzoic acid forms ortho-benzhydryl-ben-
zoic acid, C5H5.CH(OH).CgH4.C02H, by reduction. This acid, however, does
not exist in a free condition, but at the moment of its liberation from its salts de-
composes, like all the y-oxyacids, into water and its lactone, Phenyl phthalide : —

)CH.OH _ )CH.

C^H / - C,H / )0 + H^O;

\C0.0H ^CO^

this is similar to the formation of phthalide (p. 772), from o-oxymethyl benzoic
acid. The lactone, C^HioOj, is insoluble in water, crystallizes from hot alcohol
and ether in needles, and melts at 115°- It is only after protracted warming with
alkalies that it can be transformed into salts of orthobenzhydryl-benzoic acid. Like
orthophenyl-tolyl ketone and ortho-benzyl benzoic acid, it is easily changed into
anthraquinone.

Ditolyl Methane, CH /^^Hi-CHj^ Ditolyl Ketone, CO('^6][^*-^^3_

Ditolyl Ethane, CH3.CH(CgH4.CH3)2, etc. {Berichte, 18, 665), are produced
like the phenyl compounds and yield derivatives that correspond very closely to

864 ORGANIC CHEMISTRY.

them. Ditolyl chlor- ethane, CHja.CH(C5H4.CH3)2, yields on the one hand (by
alcoholic potash) ditolyl ethylene, Cll2:C[C^'H.^.CHg)2, upon the other, by aid of
heat (through , molecular rearrangement), dimethyl stilbene, CHj.CgHjCHiCH.
CgH^.CHa (comp. p. 86i).

Tolu-benzoic Acids, CO^ c^tr* rw'- "^^ para-acid is produced by oxi-

dizing ditolyl methane and ditolyl ethane (together with ditolyl ketone). It melts
at 228°. /-Tolu-o-benzoic acid results (analogous to tf-benzoyl benzoic acid) from
phthalic anhydride, toluene and AICI3. It contains one molecule of water of crys-
tallization and when anhydrous melts at 146°. It forms /3-niethyl anthracene when
heated with zinc dust. Zinc and hydrochloric acid reduce it to an oxyacid, which
changes, on liberation, into its lactpne,

C H . Cg rl^. C Hg

/ \
Tolylphthalide, CgH. - O, melting at 129°. Xylene and mesitylene
\C0/
yield similar derivatives with phthalic anhydride [Berichte, 19, Ref. 686).

Dibenzylbenzenes, C.H.^ „„2' e 5_ Xhe ortho andpara compounds are

by-products m the formation of diphenyl methane from benzyl chloride, and me-
thylal with benzene (p. 853). The former melts at 78° ; the latter at 86°.

Dibenzoylbenzenes, CjH^^ PI-.'p^tt5, phthalophenones, phenylene di-
phenyl ketones. The ortho and para derivatives are produced by the oxidation of
the corresponding dibenzylbenzenes.

The meta and para compounds may be obtained from meta- and para-phthalyl
chlorides with benzene and AICI3 (p. 856) : — ■

CeHJCOCl), + 2CeH, = CeH,(C0.C,H5), + 2HCI,

whereas, the so-called orthophthalyl chloride yields diphenylphthalide.

Orthophthalophenone melts at 146°; meta or isophthalophenone at 100°;
terephthalophenone at 160°. Hydroxylamine yields ketoximes with them
{Berichte, ig, 146, 153).

2. TRIPHENYL METHANE DERIVATIVES.
These contain three benzene nuclei attached to i carbon-atom : —

Triphenyl Diphenyl-tolyl Phenylditolyl

Methane. Methane. Methane.

These are the parent hydrocarbons from which originate the ros-
aniline dyes, the malachite-greens, tlie aurines and phthaleins.
They may be synthesized by methods analogous to those employed
with the diphenyl methane derivatives : —

I, from benzal chloride, CsHj.CHCl, (or C6H5.CCI3) and the
benzenes with zinc dust or aluminium chloride : —

C,H,.CHClj + 2CeH, = C.-R^.Q-Ri^C^n,)^ + 2HCI;

TRIPHENYL METHANE. 865

2, fro.m benzhydrol (p. 857), and the benzenes with P2O5 : —

(CeH,),CH.OH + CeH, = (CeHJ,CH.C,H, + H,0;

3, from chloroform (or CCI4) and benzene with AICI3 : —

3C,He + CHCI3 .+ (C,H,)3CH + 3HCI.

A better means is the condensation of behzaldehyde with anilines
(their salts) and phenols, in which we have produced amido- and
phenol-derivatives of triphenyl methane (p. 867). Sulphuric acid,
zinc chloride, potassium bisulphate {Berichte, 16, 2541), and anhy-
drous oxalic acid serve as reagents to induce the condensation
{Berichte, 17, 1078).

Benzaldehyde cannot be made to condense with the benzenes by the action of
sulphuric acid. This condensation only takes place, in slight degree, by the ap-
plication of intense heat, and the use of zinc chloride {Berichte, 19, 1876). How-
ever, substituted benzaldehydes, as m- and /-nitrobenzaldehyde (also terephlhal-
dehyde) condense very readily with benzenes by the aid of sulphuric acid, forming
nitrotriphenylmethanes {Berichte, 21, 188; 23, 1622). For the condensations of
benzaldehyde with phenols, see Berichte, 22, 1943.

(i) Triphenyl Methane, (C6H6)sCH = QsHib, is the product
of the reaction between benzal chloride, CgHs.CHCiz, and mercury
diphenyl, Hg(C6H5)2, and is most easily prepared from chloroform
and benzene, aided by AICI3.

Preparation. — One part of AICI3 is gradually added to a mixture consisting of
one part of chloroform and five parts of benzene, and the temperature raised to
60°, until the evolution of hydrogen chloride ceases (30 hours). The product is
poured into water, and the oil, which separates, is fractionated. Diphenyl methane
is produced at the same time [Annalen, 227, 107; Berichte, 18, Ref. 327). It is
furthermore obtained from diamido- and triamido-triphenyl methane, by dissolving
the latter in sulphuric acid, introducing nitrous acid and boiling with alcohol (p.
632 and Annalen, 206, 152).

Triphenyl methane dissolves with difficulty in cold alcohol and
glacial acetic acid, easily in ether, benzene and hot alcohol, crystal-
lizing from the latter in shining, thin leaflets, melting at 93°, and
distilling about 355°. It crystallizes from hot benzene in large
prisms, containing two molecules of benzene, and melts at 75°,
and when exposed to the air parts with benzene and falls into a
white powder.

Bromine converts triphenyl methane (dissolved in CSj) into ^t bromide, [Z^^^
CBr, melting at 152° {Berichte, 18, Ref. 327). PCI5 converts the carbinol into
the chloride, melting about 105°. When heated over 200° both decompose into

the halogen hydride and Diphenylene phenyl methane, ( (-,«jj* pCH.CgHj,

which can also be obtained from fluorene alcohol (p. 851) and benzene by means
of sulphuric acid, as well as from potassium triphenyl methane {Berichte., 22,

866 ORGANIC CHEMISTRY.

Ref. 65o). It melts at 146°. If the bromide be heated with mercuric cyanide
to loo° the cyanide, (CjHjjjC.CN, results. It melts at 127°, and if boiled with
glacial acetic acid and hydrochloric acid changes to Triphenyl-acetic Acid,
(C5H5)3.C.C02H, which begins softening at 230°, and melts at 264° [Annakn,
194, 260). Small amounts of the acid are also obtained from trichloracetic acid
and benzene with AICI3.

On boiling the bromide or chloride with water we get Triphenylcarbinol,
(05115)30.011, which is more readily obtained by the direct hydroxylation of tri-
phenyl methane. This is accomplished by digesting the latter with chromic acid
in a glacial acetic acid solution [Berichte, 14, 1944). It is very readily soluble
in alcohol, ether and benzene, crystallizes in shining prisms, melting at 159°, and
distilling above 360° without decomposition. /-Nitro-Triphenyl Methane,
C8H4(N02).CH(C5H5)2, is prepared from /-nitro benzaldehyde and benzene,
aided by sulphuric acid (see above). It crystallizes in white leaflets, melting at
93°. Chromic acid, in glacial acetic acid oxidizes it to the carbinol, O^^i^O^.
C(OH)(CgH5)j, melting at 135° {Berichte, 23, 1622).

When triphenyl methane is dissolved in fuming nitric acid (sp. gr. 1.5) it forms
a^-trinitro-derivalive, CH(CgH4.N02)3, which crystallizes from glacial acetic acid
and hot benzene in yellow scales, and melts at 206°. Sodium alcoholate converts
the nitro-compound into a deep violet-colored sodium salt (p. 861) (Berichte, 21,
1348). By the reduction of the nitro-groups (with zinc dust and glacial acetic
acid) we obtain paraleucaniline, CH(C5 H^.NH^jj (p. 870). By the hydroxylation
of the tertiary hydrogen atom of trinitrophenyl methane (by digestion with CrOj
in glacial acetic acid) we get Trinitrotriphenyl Carbinol, (CgH^.NOjjjC.OH,
which separates from benzene or glacial acetic acid in small, colorless crystals,
melting at 172°, and when the nitro-groups are reduced (with a little zinc dust and
glacial acetic acid) it is transformed into pararosaniline.

(2) Diphenyl-tolyl Methanes, (C^Yi^fM.[C^n^.CYi.^.

The /ors-compound is obtained from phenyl-paratolyl-carbinol (p. 862) and
benzene, and also from benzhydrol, (CsH5),CH.0H, and toluene with phosphorus
pentoxide. It crystallizes in thin prisms, melts at 71°, and distils above 360°. It
yields a carbinol, CjoHjgO, and an acid, C^oHuOg, when oxidized. The tri-
nitro-compound of diphenyl-para tolyl methane yields on reduction of the nitro-
to amido-groups, and further oxidation, bluish-violet coloring substances which
differ from ordinary rosaniline [Annalen, 194, 264).

Isomeric Diphenyl-meta-tolyl Methane, (C6H5)2.CH(C6H4.
CH3), is the parent hydrocarbon of ordinary leucaniline (the
triamido-compound), and is obtained from the latter by replacing
the 3NH2 groups by hydrogen. This is effected through the diazo-
compound {Annalen, 194, 282). It dissolves readily in ether,
benzene and ligroi'ne, with difficulty in cold alcohol and wood-spirit;
crystallizes in spherical aggregations of united prisms, melting at
59.5°, and distilling undecomposed above 360°. Oxidized with
chromic acid in a glacial acetic acid solution it passes into diphenyl-
metatolyl-carbinol, (C6H5),C(OH)(CeH4.CH3), melting at 150°.

It dissolves in fuming nitric acid with formation of a trinitro-
derivative, yielding on reduction common leucaniline, which is

TETRAMETHYL-DIAMIDO-TRIPHENYL METHANE. 867

oxidized (on heating with a few drops of hydrochloric acid), to
rosaniline (p. 871).

Amido-derivatives of the THphinyl Methanes.

o-Amido-triphenyl Methane, (CeH5)2CH(CeH^.NH2), is obtained from
benzhydrol, (C6H5)2CH.OH, and HCl-aniline, on heating with ZnCl^ to 150°-
It crystallizes in leaflets, or prisms, melting at 84°. Its dimethyl compound,
{^6^^5)2'-'H.C6H^.N(CH3)2, is obtained from benzhydrol and dimethyl aniline
upon heating with P^Oj, also on digesting benzophenone chloride, (Q,^Yi^.fiC\^,
with dimethyl aniline. It crystallizes from alcohol in colorless needles or prisms,
melting at 132°. It does not afford a color-base by its oxidation. [Annalen,
206, 144 and 155.)

/-Amido-triphenyl Methane, (C5H5)2CH.CeH4.NH„ is produced by re-
ducing the ^nitro derivative with tin and hydrochloric acid. It crystallizes from
ligroine in small vitreous needles, melting at 84°. When its acetyl compound is
oxidized and saponified it yields /-Amido-triphenyl Carbinol, (C8H5)2C(OH)
CjHj.NHj, the lowest analogue of the rosaniline bases. It crystallizes from a
mixture of ether and ligroine in colorless warts, melting at 1 16°. It combines
with acids [without loss of water) to form red colored salts. These, however,
lack coloring properties. {Berichte, 23, 1621).

Diamido-triphenyl Methane, C6H5.CH(C6H4.NH2)2, the pa-
rent substance of malachite-green, is obtained from benzal chloride,
C6H5.CHCI2, and aniline with zinc dust (see below), or more easily
from benzaldehyde with aniline hydrochloride on heating with
zinc chloride to 120°, and boiling the first formed product with
dilute sulphuric acid. If aniline sulphate be applied we get the
diamido-base directly (^Berichte, 15, 676) : —

CeHj.CHO + 2C,H,.NH2 = C,H5.CH(C,H,.NH2), + Ufi.

It is more readily obtained by boiling benzaldehyde with aniline
and hydrochloric acid (^Berichte, 18, Ref 334). It crystallizes
from benzene with i molecule of benzene in shining prisms or
spherical aggregations, melting at 106°, and parting with benzene
at 110°. The free base, crystallized from ether, melts at 139°.

It yields colorless salts with two equivalents of the acids. By their oxidation
we can obtain a violet dye-stuff, benzal molet^\!Oa a constitution analogous to that
of the rosanilines {Annalen, 206, 161). If the base be diazotized and boiled wiih
water it is converted into dioxy-triphenyl-methane, C5H5.CH(C5H4.0H)2 ; the
decomposition of the diazo-compound by alkalies produces triphenyl-methane
(Annalen, 206, 152).

On methylating diamidotriphenyl-methane by heating with methyl iodide and
wood-spirit to 110° we obtain

Tetramethyl-diamido-triphenyl Methane, C6H5.CH[C6H4.
N(CH3)2]2, leucomalachite green, which is obtained directly from
benzaldehyde (or benzal chloride) and dimethyl aniline with zinc
chloride (or oxalic acid) : —

C,H,.CHO + 2C,H,.N(CH,)2 = CeH,.CH/^«g4-N(CH,)2 + h^O.

868 ORGANIC CHEMISTRY.

Leucomalachite-green is dimorphous, and crystallizes in leaflets,
melting at 93-94°, or in needles, which melt at 102°. The first •
modification is obtained pure by crystallization firom alcohol, the
second from benzene. It yields colorless salts with two equivalents
of the acids, and with two molecules of methyl iodide forms an
ammonium iodide. The free base oxidizes, even in the air, more
readily by oxidizing agents (manganese dioxide and dilute sulphuric
acid in the cold, lead dioxide and hydrochloric acid, or chlor-
anil) and becomes

Tetramethyl-diamido-triphenyl Carbinol, CsHj-CCOH)
[C6H4.N(CH3)2]2, which is the basis of malachite-green. It is ob-
tained from its salts (malachite-green) by precipitation with the
alkalies. Free carbinol crystallizes from ligroine in colorless needles
or spherical aggregations, melting at 130°, and decomposes on
stronger heating. Reduction with zinc and hydrochloric acid con-
verts it again into leucomalachite-green.

The free base yields almost colorless solutions with acids in the
cold ; upon standing, more rapidly on heating, the solution acquires
a green color and then contains the green salts — malachite-greens —
of the anhydro-base. It is very probable that amine salts (O. and
E. Fischer) of the carbinol are first produced, but by an inner con-
densation water is eliminated and they change to dye-salts (mala-
chite-greens) {Berichte, 12, 2348) free from oxygen: —

C^H,^ /CeH,.N(CH3),HCl_

(ch3),n.c,h/ \oh ~

)C/ ^N(CH3),C1 -f HA

(CH3),N.CeH,

Oi these salts the double salt with zinc chloride, 3(C23H25N2.C1)
zZnClj + 2H2O, and the oxalate, 2C23H24N2.3C2H2O4, form the
commercial malachite- green or Victoria green. They are mostly
soluble in water, and crystallize in large, greenish prisms or plates.
The alkalies precipitate the colorless carbinol base from its salts.
Malachite-green and brilliant green (see below) color silk and wool,
from feeble acid baths, an intense green. This also occurs with
cotton mordanted with tannin and alumina, or tannin and tartar
emetic.

. Malachite-green is obtained by oxidizing leucomalachite-green, prepared from
benzaldehyde (p. 867), hence called aldehyde green (O. Fischer), or more directly,
though less advantageously, on heating benzo-trichloride with dimethyl aniline
and zinc chloride (Doebner) : —

CeH^.CClj -f 2C,H,.N(CH3)2 = CiaHi3(CH3),N2Cl + 2HCI.

Since success has attended the efforts made to prepare benzaldehyde the first

PARA-NITRO-DIAMIDO-TRIPHENYL METHANE. 869

process has been almost exclusively followed in the technical preparation of the
color.

Benzoyl chloride, CgH5.CO.Cl, and benzoic anhydride [Annalen, 206, 137) are
similarly condensed with dimethyl aniline to malachite-green.

Benzaldehyde forms perfectly analogous green color substances with diethyl
aniline and methyl dipbenylamine, (CgH5)fN.CH3. The dye-substance obtained
from diethyl aniline shows a yellow-tinted green color. Its sulphate or zinc-
chloride double salt constitutes what In commerce is known as brilliant green or
solid green (new Victoria green). Dichlorbenzaldehyde, CgHjClj.CHO, and
dimethyl- and diethyl-anilines yield dyes, which are applied as indigo substitutes
(instead of the mixed greens derived from indigo). By condensing benzaldehyde
and benzyl-ethyl aniline, CeH5.N(CH3).CH2.C5H5, and introducing sulphur
into the product, the light greens, guinea green or acid green iBerichte, 22, 588)
are produced ; they show the same color in artificial light.

It reacts in the same way with ortho- and meta-dimethyl toluidine, whereas no
condensation product is furnished by the para-dimethyl toluidine. The base from
meta-toluidine does not yield a coloring substance when oxidized {^Annalen, 206,
140). Salicylic aldehyde and paraoxybenzaldehyde afford green coloring sub-
stances. Furthermore, nitromalachite-greens have been prepared from meta-,
para-, and ortho-nitrobenzaldehydes with dimethyl aniline. They are perfectly
analogous to ordinary malachite-green {^Berichte, 15, 682). See Berichte, 22,
3207, for the condensations with toluidines.

The Diphenyl-diamido-triphenyl Carbinol,

'"6'^=-^^^'^\C8Hi.NH.C5H5'

obtained from diphenylamine and benzo-trichloride, and called viridin, readily
yields a sulpho-acid. The alkali salts of this acid constitute the so-called alkali
green (^Berichte, 15, 1580).

By heating leucomalachite green with sulphuric acid and then further oxidizing,
or by directly introducing sulphur into malachite green, sulpho-acids result ; their
sodium salts are applied under the names Helvetia green or acid green.

Para-nitro-diamido-triphenyl Methane, like diamldo-tri-
phenyl methane (p. 867), is obtained from paranitrobenzaldehyde
and aniline sulphate when heated with zinc chloride : —

CgH^(N0,).CHO + 2C6H5.NH, = CeH:^(N0,,).CH(C5H,.NH,), + H,0.

Paranitro-diamido-triphenyl Methane.

On reduction with zinc and acetic acid this yields triamido-tri-
phenyl methane, (Q^^.'^Yi^fl.Yi., paraleucaniline,

Meta-nitro-diamido-triphenyl Methane, similarly obtained from m-nitro-
benzaldehyde, melts at 136°, and by reduction yields pseudo-leucaniline, CH
(CjH^.NH2)g, isomeric with paraleucaniline ; in it the amido-group assumes the
meta-position in one benzene nucleus, whereas, in all other diamido- and triamido-
triphenyl methanes, the amide groups occupy the para-position (p. 870). It oxid-
izes to a violet coloring substance. Ortholeucaniline, from o-nitro-benzaldehyde,
is oxidized to a brown coloring substance (Berichte, 16, 1305 ; 17, 1889).

Benzaldehyde and nitrobenzaldehydes also condense with 0- and /-toluidine
(Berichte, 18, 2094), whereas raetatoluidine and aniline meta-derivatives only
react with ease, provided that the amido-group is methylated {^Berichte, 20, 1563).

870 ORGANIC CHEMISTRY.

TRIAMIDO-TRIPHENYL METHANES. ROSANILINES.
H:N:c:H:>CH-CeH..NH, i:S:c:H:>CH.CeH3(CH3).NH,

Triamido-triphenyl Methane, , Triamido-diphenyl-tolyl Methane,

Paraleucaniline. Leucaniline.

The rosaniline coloring substances are produced from these iti a
manner similar to the derivation of benzal violet and malachite green
from diamidotriphenyl methane (p. 867). The carbinols pr free
rosaniline bases result when they are oxidized (adding hydroxyl to
the CH-group) : — ,

H.N.CeH^^ ^CeH^.NH, H,N.C,H^^ ^CeH3(CH3).NH,

Fararosaniline Base. Rosaniline Base.

These alone are colorless, but yield salts with the acids by exit of
water (analogous to the malachite-green base) and form the rosani-
line dye-substances. E. and O. Fischer contend that the salt is pro-
duced as follows : an exit of water occurs, followed by a peculiar
linking of the C-atom to an N-atom in the para-position, forming a
chromogenic group which imparts to the rosanilines their dyeing
properties {Berichte, 12, 2350) : —

H,N.C,H, /C,H, V H,N.C,H, C,H3(CH3)

)C/ -iNH.HX yCil \ V

' HjjN.CgH/ H^N.CgH/ ^~~--.NH.HX
Para-rosaniline Salt, Rosaniline Salt.

By the replacement of the hydrogen of the amido-groups in the
salts by alkyls or phenyls, the different colored rosaniline dyes re-
sult. The common and first discovered rosanilines are derived
from diphenyl-raeta-tolyl methane, C2oHi8(p. 866), and the carbinol
base, C20H20 (0H)N3, and can also be called salts of the anhydride
base, C20H19N3 ; the latter is unstable in a free state, and when lib-
erated from its salts by alkalies, absorbs water and changes imme-
diately to the carbinol base. The derivatives of triphenyl methane,
C19H15, and of the base, Ci9Hi8(OH)N3 or CisHuNj are termed
pararosanilines, to distinguish them from those rosanilines just men-
tioned. The colorless salts obtained by the reduction of the rosani-
lines form bases, C19H19N3 and C20H21N3, called leucanilines.

Triamido-triphenyl Methane, C19H19N3 = CH(C6H4.NH2)3,
Paraleucaniline, is obtained from trinitro-triphenyl methane
(p. 866) and from para-nitro-diamidotriphenyl methane (p. 869)
by reduction with zinc dust and acetic acid, also from para-
rosaniline with zinc dust and hydrochloric acid, and by heating
/-amidobenzaldehyde and dimethylaniline with zinc chloride: —

C5H,(NH2).CHO + 2C3H5.NH2 = CH(CsH,.NH2)3 + HjO.

ROSANILINE. 87I

It is thrown out of its salts as a white flocculent precipitate. When
its diazo-compound, Ci9Hi3(N2Cl)3, is decomposed by alcohol, it
yields triphenyl methane, QgHie. Pararosaniline is the oxidation
product of para-leucaniline. Pseudo-leucaniline affords a violet,
and ortho-leucaniline a brown coloring substance when oxidized
(p. 870).

Pararosaniline. • The free base, C19H1SN3O = (NH^-CsHOsC.
OH, or its salts, Ci^HitNj.HX (see above), result in the oxidation
of para-leucaniline and in the reduction of trinitrophenyl carbinol
(p. 866), with a little zinc dust and glacial acetic acid. It is most
easily made by oxidizing a mixture of aniline and paratoluidine by
arsenic acid (p. 872). In its properties and derivatives it is per-
fectly analogous to rosaniline. Its diazochloride, Ci9Hi2(OH)N6Cl3,
yields aurine, CisHjiOs, when boiled with water.

In para-rosaniline and in para-leucaniline tlie amide groups in the three benzene
nuclei occupy the para-position (referred to the point of union of the methane
carbon). We infer this from the synthetic methods (from para-nitrobenzaldehyde
and para-amidobenzaldehyde) and from their relations to the aurines and to para-
dioxybenzophenone (p. 860) {Berichte, 14, 330). It is very probable that common
rosaniline contains its amide-groups in the same position; as it is obtained by
means of ortho-toluidine the methyl in it occupies the meta-position referred to the
methane carbon. See Berichte, 22, 2573 as to the influence exerted by side-groups
upon the dye-character of the rosanilines.

Triamido-diphenyl-tolyl Methane, Leucaniline, CjoHji.
N3 = (NH2.C6H4),CH.CsH3(CH3).NH.„ is obtained by the reduc-
tion of trinitro-diphenyl meta-tolyl methane (p. 866), and is ob-
tained by digesting the fuchsine salts with ammonium sulphide, or
zinc dust and hydrochloric acid. The alkalies throw it out from
its salts as a white, flocculent precipitate, which separates from water
in small crystals. It yields colorless crystalline salts with three
equivalents of acid. By diazotizing and replacing the diazo-groups
by hydrogen (best by dissolving in concentrated sulphuric acid,
conducting nitrous acid into the same, and boiling with alcohol, p.
632), leucaniline is changed into diphenyl-meta-tolyl methane.
Oxidizing agents convert it into rosaniline (its salts).

The oxidation of the leucanilines to rosanilines succeeds best when they are
heated with a concentrated arsenic acid solution, or with metallic oxides to 130^
140°, or by boiling the alcoholic solution with chloranil. Paraleucaniline and
common leucaniline are also converted into coloring substances by heating them
with a few drops of hydrochloric acid upon a platinum foil. This behavior rapidly
distinguishes the second from some isomerides (Annalen, 194, 284).

Rosaniline, C20H21N3O. The rosaniline salts, C^oHigNa.HX (p.
870), are obtained in the oxidation of leucaniline, and are techni-
cally prepared by oxidizing a mixture of aniline and ortho- and
para-toluidine (see below). Alkalies precipitate the free base (the

872 , ORGANIC CHEMISTRY.

carbinol), CaoHjiNjO, from the salt solution; it crystallizes from
alcohol and hot water in colorless needles or plates. It reddens on
exposure, and when heated suffers decomposition. Its diazo-com-
pounds, <?. g., C2oH„(OH)N6Cl8, are produced when nitrous acid
acts on the rosaniline salts, and when boiled with water they afford
rosolic acid, CjoHigOs.

Free rosaniline, C20H21N3O, is a base, which will expel ammonia
from the ammonium salts. It combines with one and three equiva-
lents of acids, undergoing an anhydride formation (p. 870), and
yields salts, e. g. , CmHi^Ns. HCl and C20H19NS.3HCI + 4H2O. The
latter are yellow-brown in color and not very stable ; water decom-
poses them into the stable, monacid salts with intense colors. These
are applied as dyes. They are most readily soluble in water and
alcohol, and crystallize readily in metallic, greenish crystals. Their
solutions are carmine red in color, and stain animal tissue directly
violet-red, while vegetable fibre (cotton) must first be mordanted
(tannin). The commercial fuchsine (magenta) consists chiefly of
the hydrochloride or acetate, CjoHigNj. CaH^Oj. The fatty acid
salts, insoluble in water and produced by dissolving the free rosani-
line base in fatty acids, are employed in decorative printing.

All the.rosanilines are changed to colorless leucanilines when
treated with reducing agents (heating to 120° with ammonium sul-
phide). When heated to 200° with hydrochloric or hydriodic
acid, the rosanilines are broken up into their component anilines.
Upon boiling with hydrochloric acid pararosaniline breaks down
into aniline and diamidobenzophenone (p. 859), and rosaniline
into toluidine and diamidobenzophenone.

Preparation. — Technically the rosaniline salts are obtained by oxidizing
aniline oil (a mixture of aniline with para- and ortho-toluidine) with metallic salts
(tin chloride, mercuric nitrate) or more advantageously with arsenic acid. If
pure aniline be employed no coloring substance is formed. When pure aniline
and paratoluidine are used pararosaniline results : —

2C6H5.NH, -I- C,H,.NH2 + 30 = C,3H„N,0 + 2H,0;
Paratoluidine. Pararosaniline,

whereas common rosaniline is obtained from aniline, paratoluidine and ortho-
toluidine [Berichte, 13, 2264; 15, 2367) : —

C5H5.NH2 -f- 2C,H7.NH, -f 3O = C20H N3O -f- 2H2O.

Rosaniline.

The reaction probably occurs in such a manner that para-amido benzaldehyde
is first produced from the paratoluidine, and this then (like para-nitrobenzalde-
hyde, p. 869) condenses with two aniline molecules to the leuco-bases : —

NH,.CsH,.CHO -)- 2CeH.,.NH2 = NH2.C,H,.CH(CeH,.NH,), -f- H^O,

which further oxidizes to rosaniline.

ALKYLIC ROSANILINES. 873

An interesting formation of pararosaniline is that of heating aniline with carbon
tetrachloride to 230° when the latter furnishes the linking carbon atom, and there
ensues a reaction analogous to that of the formation of triphenyl methane from
benzene and CCI3H or CCI4 {865). The hydroiodide of pararosaniline results by
using iodoform, CHI3 (Care).

In the preparation of rosaniline according to the arsenic acid method (Girard
and Medloc) aniline oil, or better, the proper mixture of aniline and toluidine is
heated to 180-200° for 7-10 hours with a concentrated arsenic acid (^ part) solu-
tion in iron retorts with agitators until the mass assumes a metallic lustre. The
product, consisting chiefly of rosaniline arsenite, is extracted with water and fil-
tered. When the solution cools a violet dye-substance separates, and upon the addi-
tion of common salt rosaniline hydrochloride crystallizes out. The crystals thus
obtained contain arsenic, but are freed from it by repeated crystallizations.

According to another method (by Coupler) applied technically, the oxidizing
agent is either nitrobenzene or nitrotoluene.

To obtain red, heat aniline oil (a mixture of aniline,/- and o-toluidine), one
half of it being converted into hydrochloride, with 50 per cent, nitrobenzene and
a httle ferrous chloride or ammonium vanadate to 180-190° in an oil bath. Extract
the rosaniline hydrochloride with water. In these changes the nitrobenzene acts
as an oxidizer, and does not take part in the formation of the rosaniline (Lange,
Berichte, 18, 1918).

The commercial dyestuffs, obtained as described, are really salts
of rosaniline, C20H19N3, and apparently contain, although in slight
quantity, salts of pararosaniline, CigH^Nj, and the homologous base,
C21H21N3. In addition to the rosaniline the fusion also contains
other violet and brown dyes, such as mauvein (viol-aniline), an
azine dyestuff, and chrysaniline, an acridine derivative. 'Y:\\e.fuch-
sine absolutely free from arsenic, which is obtained from it by a
transposition with sodium chloride, is called rubine. Salt precipi-
tates red-brown dye-substances from the mother liquors.

Verguin (1859) first prepared rosaniline upon a large scale and introduced it
into commerce under the name fuchsine. A. W. Hofmann has studied it scien-
tifically since i85i ; he proved the fuchsine salts to be salts of a base C2„H,gN3.
HjO. The true constitution of the rosanilines — the proof that they were deriva-
tives of triphenylmethane— was demonstrated analytically and synthetically by Emil
and Otto Fischer (1876, Annalen, 194, 242), although preliminary investigations
in this direction had been previously made by Caro and Graebe. {Berichie, 1 1 ,
1116,1348).

Alkylic Rosanilines.

When the rosaniline salts are heated with alkyl iodides or chlo-
rides (and the alcohols) the hydrogen of the amido-groups can be
replaced by alkyls. Of the trialkylic compounds —

C,oH„(OH)N3(CH3)3 and C2„H.,(OH)N3(C,H5)3,

resulting in this manner, the methyl base yields reddish-violet-
colored salts and the ethyl base pure violet salts (Hofmann's Violet,
Dahlia); these dissolve with difficulty in water, but dissolve easily
in alcohol.
73

874 ORGANIC CHEMISTRY.

The introduction of more methyl affords higher methylated dyes
until hexamethyl rosaniline is reached ; its color changes with the
number of methyl groups, from red to violet.

Hexamethyl-rosaniline is capable of uniting with CH,! (i molecule) to form
a. green colored salt C2|,HnN3(CH3)gI.CH3l, that at 120° again eliminates methyl
iodide and yields a bluish violet iodide, C2oH,4N3.(CH3)8l. The picrate, a dark
green powder, and the crystalline ZnCl^-double salt, readily soluble in water, con-
stituted the iodide green or night green of commerce, but at present are sup-
planted by the cheaper methyl- and malachite-greens.

Similarly, hexamethyl pararosaniline, Ci9Hj2(OH)N3(CH3)g (methyl violet, see
below), when heated with methyl chloride (methyl iodide or methyl nitrate) yields
so-called methyl green ; its hydrochloride, C,gHj2NjCl(CH3)5(CH3Cl), as the
zinc chloride double salt, forms the commercial dye. It occurs as a bright gold and
green mass. At 100-120° methyl green loses methyl chloride and becomes violet.
At present both are almost entirely replaced by malachite green.

Aldehyde green, another green rosaniline dye, has been prepared by heating
rosaniline with aldehyde and sulphuric acid, and by further action of sodium hy-
posulphite. It is very probably a quinaldine [Berichte, 19, 749)-

The phenylated rosanilines are obtained by heating rosaniline hydrochloride
with aniline or toluidines (p. 603), or the free base with aniline and some benzoic
acid. The triphenyl-rosaniline hydrochloride, C25Hi5(C5H5)3N3.HCl, appeared
in commerce as aniline blue, a bluish-brown crystalline powder with copper lustre,
soluble in alcohol but not in water. To dissolve it in the latter sulpho-salts are
prepared, which exhibit different shades of blue {soluble blue) corresponding to
the number of sulpho-groups in them. At present diphenylamine blue and other
dyes have taken its place. Diphenylamine results on distilling triphenyl-rosaniline.

Pararosaniline Derivatives. Instead of first preparing rosaniline
and then adding alkyl, it was suggested that the same compounds
could be obtained by directly oxidizing alkyl anilines (dimethyl
aniline, diphenylmethylamine). The resulting dyes, according to
their method of preparation, are derivatives of pararosaniline,
Ci9Hi,N3. They are obtained by oxidizing trimethyl aniline upon
digesting it with copper chloride (or copper sulphate) and potas-
sium chlorate at 50-60°. On a small scale the oxidation is best
effected by means of chloranil, CsCliOj (p. 701). The reaction very
likely proceeds as follows : A methyl group splits off and is
oxidized to formic aldehyde, which then condenses three molecules
of the alkyl anilines : —

CH,0 -h 3CeH5.N(CH3), -f O, = C(OH)[CeH,.N(CH3),]3 + 2HjO.

The methyl violet thus formed occurs in commerce in the form of
hydrochloride, an amorphous bright green mass, easily soluble in
water and alcohol. It consists chiefly of penta- and hexamethyl-
rosaniline, and also contains the tri- and tetramethyl compounds,
which are separated by fractional crystallization with difficulty

PARAROSANILINE DERIVATIVES. 875

{Berichte, 19, 107). As the number of methyl groups increases the
violet color assumes a deeper blue tint.

The following methyl derivatives have been obtained in a pure state : —

Tetra-methyl Para-leucaniline, H^l^.CeH^.CH/^egt-^^^gsK is ob-
tained by reducing /-nitro-malachite-green (p. 869), formed from para-nitrobenz-
aldehyde and dimethyl aniline. It melts at 152°. It is oxidized to Tetra-
methyl Violet, Cjs,Hi3fCH3)^N3.HCl. The acetate of paraleucaniliue may be
oxidized to a green dye (a malachite-green, as one NH^-group is linked by acetyl)
(Berichte, 16, 708).

Pentamethyl-para-leucaniline, CijHi4(CH3)5N3, has been obtained from
the reduction product of commercial methyl violet (a mixture of penta- and hexa-
methyl violet) by means of the acetate. It melts at ii6°, and when oxidized
yields Penta-methyl Violet, C,gHi2(CH3)5N3.HCl. When its ac^/ai^i? is oxid-
ized it yields a green dye [Berichte, i6, 2906).

Hexamethyl-paraleucaniline, CigHj3(CH,)gNg, Leuco-violet, is obtained
pure on heating ortho-formic ester, CH(O.C2H5)3, with dimethyl aniline (3 mole-
ailes) and zinc chloride, and from tetramethyldiamidobenzophenone (p. 859)
with dimethyl aniline and PCI3. If separated from its HCl-salt it crystallizes in
silvery leaflets, and melts at 173°. If oxidized it yields Hexamethyl Violet : —

Ci„Hi,(CH3),N3.Ha = (CH3),N.C3H,.c/^«g*^-]J(gg3)2^j_

this possesses a blue tint. Its carbinol base, CigHi2(OH)N3(CH3)j, crystallized
from ether, melts at 195°-

AU three leucanilines yield the iodo-methylate, CjgHj3(CH3)5N3.3CH3l, when
they are heated with much methyl iodide and methyl alcohol. This melts at 185°,
and heated to 130° regenerates hexamethyl-para leucaniline.

The methyl violets are reduced to leuco-compounds when heated to 120° with-
ammonium sulphide. Protracted boiling with hydrochloric acid causes them to
lose one molecule of dimethylaniline and break down. Thus from pentamethyl

violet we obtain trimethyl-diamidobenzophenone, C0(' p°ij* ■m/pVt \'' ^"'^

from hexamethyl violet, tetramethyldiamido-benzophenone (p. 859) (Berichte, 19,
108).

Pure hexamethyl pararosaniline, distinguished from the lower
methyl derivatives by great power of crystallization and the blue
color of its salts, hence called Crystal Violet, is produced on a large
scale by the condensation of tetramethyldiamidobenzophenone
(from dimethyl aniline and COClj, p. 859) with dimethyl ani-
line : —

.CeH,.N(CH3), /CeH^.N(CH3),

C0( -K.CeH,.N(CH3), = C(0H)^CeH^.N(CH3),.

\C«H,.N(CH3), ^ \C„H,.N(CH3),

It may therefore be directly obtained by heating dimethylaniline
with COCI2 and AICI3 or ZnCl^ {Berichte, 18, 767; Ref. 7).
Formic acid, formic ester, chlorcarbonic ester, perchlormethyl
mercaptan, CSCI2, etc., act the same as phosgene.

876 ORGANIC CHEMISTRY.

Tetramethyl-diamido benzophenene condenses similarly with
other bases. It yields with phenyl-a-napthylamine, CgHs-NH.

Ci„H„ tetramethyl-naphthyl-rosaniUne, ^{^^)(^^^j^^Q^''-

The zinc chloride double salt of the latter is Victoria Blue, used
for cotton dyeing (see Berichte, 22, 1888).

Diphenylamine Blue can be obtained by heating diphenylamine, (CjHjjjHN, with
carbon hexachloride, CjClg, or'oxalic acid, to 120°. It is identical with triphenyl-
pararosaniline, Q,{OYi){<::,^Yi.^^AYi.Z^^ {Berichte, 23, 1964), obtained by the
action of aniline upon pararosaniline. At present it is only the sodium salts of its
mono- and disulpho- acids that are applied as Alkali Blue and Water Blue in dyeing.

Perchlorformic ester, CCIO2CCI3, in a similar manner converts di-
phenyl methylamine, (C6H5)2N.CH3, into trimethyl-triphenyl-para-

rosaniline,<Z{OYi.){Q^^.'^(^^)^ {Berichte, 19, 278). Phos-
gene converts triphenylamine into the hydrochloride of hexaphenyl
pararosaniline, Q.{OW)\<Z^i.'^{(Z^^^i {Berichte, 19, 758). Tri-
carbazol Carbinol, C(OH)(C,2H,NH)3 {Berichte, 20, 1904), is
produced by heating together carbazol and oxalic acid {Berichte,
20, 1904). It is analogous to the triphenylamine derivative.

By converting rosaniline, by means of the tridiazo-compound
into the trihydrazine derivative, there results Roshydrazine, C(OH)
(C6H5.NH.NH2)3; this by condensation with aldehydes and ketones
yields red and blue dyestuffs {Berichte, 20, 1557).

2. PHENOL DERIVATIVES OF THE TRIPHENYL
METHANES.

These possess a constitution perfectly analogous to that of the
amido-derivatives, as they contain hydroxyls in the positions held
by the amido-groups. They are synthetically produced in a similar
manner by the condensation of the phenols, and on the other
hand may be obtained from the amido-compounds by means of the
diazo-derivatives. Their leuco-derivatives (p. 870), are oxidized
to carbinols, R3C.OH, having usually the properties of a dye-sub-
stance. Those compounds, in which but two benzene nuclei are
hydroxylated, and which correspond to the diamido or malachite-
green compounds, are termed benzeines, whereas the derivatives
with three hydroxylated benzene nuclei are called aurines or rosolic
acids : —

Leuco-benzei'ne. Benzei'ne.

HO.C.H HO.C.H,

)CH.C.H,.OH )C(OH).C.H..0H.

HO.CeH/ HO.CeH/

Leuco-aurine. Aurine*

AURINES AND ROSOLIC ACIDS. 877

Benzeines.

Dioxy-triphenyl Methane, CigHigO^ = CpH5.CH(C5H4.0H)j, leuco-
benzeine, formerly called leucobenzaurine, is obtained from diamido-triphenyl
methane (p. 867), with nitrous acid and by reducing benzaurine with zinc and hy-
drochloric acid as well as by the condensation of benzaldehyde and phenol (2
molecules) with sulphuric acid [Berichte, 22, 1944). It crystallizes from dilute
alcohol in yellow needles or prisms, melting at 161°. When oxidized it yields
benzeine.

Dioxy-triphenyl Carbinol, CigHjgOs = CeH5.C(0H)(CsH^.0H)j, Phenol
Benzeine, is only stable as an anhydride, CigHj^Oj, formerly called benzaurine.
It is produced in the condensation of benzotrichloride and phenol (similar to
the formation of malachite-green) [Doebner, Annalen, 217, 223) : —

CeH,.CCl3 + 2C,H5.0H + H,0 = C^H^Oj -h 3HCI.

All mono- and polyhydric phenols, in which the para position with reference to
a hydroxyl group is not substituted, s. g., 0- and w-cresol, a-naphthol, resorcinol
and pyrocatechin (but not /-cresol, |SnaphthoI, hydroquinone etc.) [Berichie, 23,
Ref. 340), react in the same manner with the formation of benzeines.

The benzeines are generally red-colored compounds with metallic lustre. They
dissolve on boiling with sodium bisulphite; acids reprecipitate them. Alkalies
dissolve them With the formation of red or violet-colored salts. The carbon di-
oxide of the air decomposes the latter.

Phenol benzeine (see above) breaks down, when fused with alkalies, into ben-
zene and dioxybenzophenone, and this latter decomposes further into paraoxy-
benzoic acid and phenol. The other benzeines react similarly.

a-Naphthol Benzeine, 2(^C5H5.C(OH)/^i»^6q^ ^ — H^O.from benzo-
trichloride and naphthol [Annalen, 257, 58), dissolves with a dark green color, in
alkalies; acids color it reddish-yellow. It is extensively employed as a delicate
indicator {Chem. Zeitschr., 1890, 605).

The benzeines, from phenols, possess but feeble dyeing properties, as their
alkali salts are even decomposed by carbon dioxide. On the other hand the
diamidobenzeines from benzotrichloride and »«-amidophenols, combining the ben-
zeine character with that of the malachite greens, are called rosamines, and in
their salts with acids are very intense, true dyestuffs {Berichte, 22, 3001) : — •

NH,
/

C^U,.CC\, + 2C,H,<^°g^ = CeH5.C(0H)/ ^O + 3HCI.

\

NH,

In a similar manner, dimethyl and-diethyl-»i-amidophenol yield tetramethyl-
and tetraethyl-rosamines, which find application as violet red dye substances.
They are strongly fluorescent.

AURINES AND ROSOLIC ACIDS.

These compounds correspond perfectly to the rosanilines. They
contain three hydroxylated benzene nuclei (p. 876) and in the free
state are peculiar carbinol anhydrides. They are incompletely fixed

878 ORGANIC CHEMISTRY.

by the fibre of the material and are only applied in the form of
lakes.

Trioxy-triphenyl Methane, CigHijOj = CH(CjH4^.0H)3, Leucaurine.
This is obtained in the reduction of aurine, its carbinol anhydride, by means of
zinc dust. It dissolves in alcohol and acetic acid, and crystallizes in colorless
needles, which become colored on exposure to the air.

Aurine, CigHi403 (para-rosolic acid), is produced on boiling the diazo-
hydrochloride of pararosaniline with water, when the carbinol formed at first
splits off water [Annalen, 194, 301) ; —

ClN,.CeH,\c/CeH,.N,a . ,, HO.CeH,\(,/C,H,\

CIN^.C^H./^XOH y'^"" HO.CeH^/*- O;

Diazochloride. Aurine.

also by the condensation of dioxybenzophenone chloride (from /-dioxybenzo-
phenone, p. 860) with phenol : —

CC1,(C6H,.0H), + CeH,.OH. = CjeH^A + 2HCI,

and by the condensation of phenol with formic acid on heating with zinc chloride.
It is made by heating phenol with oxalic and sulphuric acids ; the combining car-
bon atom is derived from the oxalic acid.

The method of Kolbe and Schmitt (1S61) is that technically employed for the
manufacture of aurine or yellow corallin. It consists in heating phenol (l part)
and anhydrous oxalic acid (J^ part) with sulphuric acid (^ part) to 130-150°,
until the liberation of gas ceases [Annalen, 202, 185). On extracting with water
there remains a resinous metallic green mass which forms a yellow powder. It
contains, besides aurine, various other, quite similar, substances, from which the
first can be separated either by means of sulphurous acid (Annalen, 194, 123), or
by precipitation as aurine-ammonia, when NHj is conducted into the alcoholic
solution {Annalen, 196, 177).

Aurine dissolves in glacial acetic acid and alcohol, crystallizes in dark red
needles or prisms with metallic lustre, and decomposes when heated above
220°. Acids precipitate it from the alkaline fuchsine-red solutions. When am-
monia is conducted into the alcoholic solution, the ammonium salt, Cjglljj
(NHjj^Oj, separates in dark red needles with a steel-blue lustre. With the
primary alkaline sulphites it also yields colorless, crystalline derivatives, decom-
posable by acids and alkalies. Aurine forms crystalline compounds with hydro-
chloric acid. Water decomposes them. Digested with zinc dust and hydrochloric
acid or acetic acid, aurine is reduced to leucaurine, CjjHjgOg. Heated to 250°
with water it breaks up into dioxybenzophenone and phenol : — •

q^HiA + H,0 = CO(CeH,.OH), + C^Hs.OH.

Aurine is changed to pararosaniline when it is heated with aqueous ammonia
to 150°. An intermediate product (having I or 2 amide groups) is the so-called
Peonine (red corallin). With aniline we obtain triphenyl-rosaniline, and the inter-
mediate product is Azuline.

Leuco-rosolic Acid, C^n^f)^ = (HO.C6H4)j.CH.C8H3(CH3).OH, trioxy-
diphenyl-tolyl methane, and Rosolic Acid, C2„Hj803, corresponding to leuco-
aniline and rosaniline, are constituted similarly to leucaurine and aurine, and resem-
ble them in all their reactions. Rosolic acid, like aurine, is obtained by boilingthe
diazochloride of rosaniline with water and by oxidizing a mixture of phenol and
cresol, €5114(0113)011, with arsenic acid and sulphuric acid, whereby the linking
methane carbon is furnished by the methyl group. When rosolic acid is digested
with alcohol and zinc dust, it is reduced to leucorosolic acid.

PHTHALIDES. 879

The so-called Pittical belongs to the aurine series. It was first obtained in
oxidizing the fractions of beech-wood tar, boiling at high temperatures. It con-
sists of the dark blue salts of Eupittonic acid (Eupitton), which, in its uncombined
state, shows an orange-yellow color. It can be synthesized (analogous to rosolic
acid) by oxidizing a mixture of the dimethyl ester of pyrogallic acid and methyl
pyrogallic acid (p. 695) : —

2CeH3 { g^if "»^» + C,H,(CH3) { [^f ^3)' = C,,H,,0, + 3H,.

Eupitton is, therefore, an aurine, into which six methoxyl groups have been
introduced (comp. Berichte, 21, 1371) : —

C25H26O9 = Ci9H8(O.CH3)503.

Eupitton forms orange- yellow crystals, melting with decomposition at 200°. It
dissolves with a deep blue color in alkalies yielding salts, which are precipitated
by excess of alkali. When heated with ammonia it suffers a replacement of its
hydroxyls by amido-groups, just like aurine, and affords a body resembling rosani-
line, which must be considered as hexamethoxyl-rosaniline.

CARBOXYL DERIVATIVES OF THE TRIPHENYL METHANES.
PHTHALIDES.

Of the many possible carboxyl derivatives of the triphenyl me-
thanes (their amido- and phenol derivatives), there is one group of
compounds of particular interest. These contain a carboxyl in the
benzene nucleus in the ortho position (in relation to the combining
methane carbon).*

By oxidation they yield carbinol acids, which, however (like all
^-oxyacids), are not stable, but immediately sustain a loss of water
and pass into their anhydrides (lactones) : —

Ortho-carboxylic Acid. Carbinol-carboxylic Acid.

(C,H,),C/C«^*)C0

Anhydride.

These anhydrides bear exactly the same relation to the carbinol-
carboxylic acids that the so-called Phthalide bears to the unstable
ortho-oxy-methyl benzoic acid (p. 772). It is, therefore, conve-
nient to regard the compounds belonging here as derivatives of
phthalide, produced by the substitution of phenyls (oxy- and amido-
phenyls) for the hydrogen of the CHj-group : —

C6H4<5ifcoi^l>0 CsHX^6l^*Q^^>0 C6H^<^6_^*^^>0.

Diphenyl phthalide, Dioxy-diphenylphthalide, Diamido-di phenyl phthalide,

ij-Phthalophenone. Dioxyphthalophenone. Diamidophthalophenone.

* See further, A. Baeyer, Annalen^ 202, 36; 212, 347.

88o ORGANIC CHEMISTRY.

They are reduced to ortho-carboxylic acids, and may be obtained
from phthalic acid in the same manner as phthalide, hence, their
name. They are produced by the condensation of ^-phthalyl chloride
(or (?-phthalic anhydride) with benzenes, by the action of AICI3: —

CeH,/^g|)0 + 2CeH, = C,H,/^gW2\o + aHCl.

In using phthalic anhydride, we first get o-benzoyl benzoic acid (p. 863). On
permitting benzene and AICI3 to further act upon the latter, the product will be
diphenylphthalide {Berichte, 14, 1865) : —

The diphenolphthalides (phthaleins) are analogously produced by
the condensation of phthalic anhydride with phenols (p. 881).

d-Benzoyl benzoic acid reacts similarly with phenols (on heating to 200°), and
in this way phthalophenones can be obtained with one benzene and one phenol
residue {Berichte, 14, 1859).

Diphenyl Phthalide, Phthalophenone, CjoHuO^, the anhy-
dride of triphenyl carbinol-ortho-carboxylic acid, is obtained from
phthalyl chloride with benzene and -AlCls {Annalen, 202, 50), or
with mercury diphenyl, and crystallizes from alcohol in leaflets,
melting at 115°. When boiled with alkalies it dissolves to salts of
triphenyl carbinol-ortho-carboxylic acid, which is again separated
as anhydride (phthalophenone) by acids.

If the alkaline solution of the carbinol acid be boiled with zinc dust, we get
Triphenyl-methane-carboxylic Acid, (CsH5)2CH.CbH4.C02H, melting at
156°, and when carbon dioxide splits off it yields triphenyl methane. The same
product is obtained from phenylphthalide (p. 863) and benzene with AICI3 {Be-
richte, 19, Ref. 687).

Phthalophenone dissolves in nitric acid, yielding a dinitro product, whose di-
amido-derivative is converted by nitrous acid into dioxyphthalophenone (phenol
phthalein) {Annalen, 202, 68).

An interesting reaction is that triphenyl-methane carboxylic acid can, by the
elimination of water, yield phenylanthranol, a derivative of anthracene : —

\0H

The derivatives of the acid deport themselves similarly (the so-called phthalins,
p. 882); the resulting anthracene compounds are known as phthalidins (see
these).

PHTHALEINS. 881

Oxyphthalophenone, C2dH,3(OH)02, Benzene-phenol-phthalide, can be ob-
tained from phenol, in the same manner that phthalopheuone is prepared from
orthobenzoyl-benzoic acid with benzene. It melts at ISS°- It forms the transition
to the phthaleins, containing two phenol residues. It dissolves in alkalies with
a violet-red color, which disappears on heating, because the anhydride group is
ruptured and the salt of the carbinol acid produced ; this by reduction with zinc
dust yields —

Oxy-triphenyl-methane Carboxylic Acid, CjHg.CHcf C°H* CO H' ^^'^
is a phthalin. Concentrated sulphuric acid abstracts water from it and converts it
into its phthalidin (an anthracene derivative) (see above). Sulphuric acid decom-
poses oxyphthalophenone at Ioo° into phenol and o-benzoyl-benzoic acid. Fusion
with potassium hydroxide converts it into benzoic acid and oxybenzophenone.

The Phthaleins, the derivatives of phthalide containing two
phenol residues, are particularly important, and are dyes which are
of great technical value. A. v. Baeyer discovered them in 1871.
They result from the condensation of phthalic anhydride (i mol.)
with phenols (2 mols.) on heating with sulphuric acid, or better,
with ZnClj to 120° (or with oxalic acid, p. 864) : —

/CeH,.OH
yCO\ /C-»eH4.0H

CsH/ TO /O + 2<^6H5-OH = CeH / \ -f H,0,

^^^ Phenol. \CO.O

Phenol-phthalein ,

/C,H3(0H)\q
/C0\ C-CeH3(0HJ/"

^^^/ Resorcinol. ^CO.O

Resorcinol-phthaleVn.

The phthaleins derived from di- and polyvalent phenols are all
anhydrides, formed by the elimination of water from two phenol-
hydroxyls {Annalen, 212, 347).

The reaction proceeds as in the case of diphenylphthalide (p. 880) ; it may be
assumed that oxybenzoyl-benzoic acid is first formed, and this then acts with a
second molecule of the phenol. If, however, phthalic anhydride be heated to
150°, with but one molecule of phenol and sulphuric acid, anthraquinone deriva-
tives are produced : —

^«^*\Co)° + CeHs.OH = C,H,/gg\CeH3.0H + H,0.

Oxyanthraquinone.

The free phthaleins are generally colorless, crystalline bodies.
They dissolve in the alkalies with intense colorations, and are again
separated from their solutions by acids (even CO2). The addition
of concentrated caustic alkali causes the colors to disappear, because
by the rupture of the anhydride group salts of the colorless carbinol
acids are formed (p. 879). On diluting with water the colors
74

882 ORGANIC CHEMISTRY.

reappear. The phthalei'ns obtained from resorcinol and phthalic
anhydride (or the anhydrides of polybasic fatty acids, p. 883)
exhibit an intense fluorescence in these solutions, and are therefore
termed fluoresceins.

It appears the linking carbon atom (of phthalic acid) in them occupies the meta-
position referred to the two hydroxyls of the resorcinol, and, therefore, only those
meta-dioxybenzenes yield fluoresceins in which the meta-position is unoccupied
{Berichte, 15, 1375).

If the alkaline solutions of the phthaleins be reduced with zinc
dust, we obtain the non-coloring carboxylic acids (p. 879) — the
phthalins : —

C(CeH,.OH) CH(CeH,.OH),

\C0 / ^CO.OH

Phthale'in. Phthalin.

The phthaleins may be compared to the aurines, and the phthalins to the leuc-
aurines (p. 876) ; in place of the hydroxyl of the latter the phthalins contain a
carboxyl group. The hydroxyl, however, in the leucaurines is found in the para-
position, while, in accordance with their method of production, the phthalins and
phthaleins contain the CO-group in the ortho position.

The phthalins dissolve in alkalies, oxidize, however, readily in
alkaline solution (even in the air, more quickly by MnOa or
MnOiK), to phthaleins. Another interesting reaction is the con-
version of the phthalins, by mixing them with sulphuric acid, into
the so-called phthalidins (p. 882), which by oxidation yield the
phthalideins (oxanthranol derivatives) (see Anthranol).

Phenol-phthaleiin, C20H14O4, Dioxyphthalophenone, is also formed from
phthalophenone' when nitrous acid acts on the diamido-compound (p. 880). It
is obtained on heating phthalic anhydride (3 parts) with phenol (4 parts) and tin
chloride (4 parts), or with sulphuric acid to 115-120° for eight hours. The pro-
duct is boiled with water, dissolved in sodium hydroxide and precipitated by
acetic acid (Annalen, 202, 68). It is a yellow powder, crystallizing from alcohol
in colorless crusts, and melting at 250°. It dissolves in the alkalies with a red
color (see above). It is used as aii~indicator in alkalimetry, especially in deter-
mining carbon dioxide with baryta {^Berichte, 17, 1077, 1097).

Acetic anhydride converts it into a diacetate, melting at 143°, and bromine into
a tetrabromide, CjoHj^Br^O^. On fusion with alkalies it decomposes into benzoic
acid and dioxybenzophenone (p. 860). Boiling with alkaline hydroxides and
zinc dust changes phthalein into Phenol-phthalin, C^jHjgO^, crystallizing from
hot water in needles, and melting at 225°. It dissolves in alkalies without colora-
tion ; the solution oxidizes to phenol-phthalein in the air, more quickly with potas-
sium ferricyanide or permanganate.

Resorcinol-phthalein, CjjHuO, -f HjO, Fluorescein, is prepared by
heating phthalic anhydride (5 parts) with resorcinol (7 parts) to 200°. When
precipitated from its salts it is a yellowish-red powder, and when crystallized
(C20H12O5) from alcohol it is dark red in color. It decomposes about 290°. It
dissolves in alcohol with a yeltow-red color and green fluorescence. Its con-
centrated alkali solution is dark red, but on dilution it gradually becomes yellow,

DIMETHYLANILINK PHTHALEIN. 883

and then exhibits a magnificent yellowish-green fluorescence. When fused with
caustic soda it decomposes into resorcinol and monoresorcinol phthalein, which
further splits up into phthalic acid (benzoic acid) and resorcinol. Resorcinol-
phthalin, Fluorescin, C^oHj^Oj, formed Ijy reduction with zinc dust, is a color-
less, amorphous substance, which is again oxidized to fluorescein, when its alkaline
solution is exposed to the air.

If bromine be allowed to act on fluorescein suspended in glacial acetic acid,
we obtain substitution products, of which Tetrabromfluorescein, CjjHgBr^Oj,
is the commercially important dye, Eosin (Caro). When thrown out of solution
it is a yellowish-red precipitate; crystallized from alcohol it forms red crystals.
The po/ass!Mm salt, Q,^^^V^^xfi^, containing 6 and 5 molecules of H^O, is a
red-brown powder with shining leaflets, and constitutes the eosin of commerce,
soluble in water, and imparting to wool and silk a beautiful rose color (similar to
cochineal). A benzyl derivative of fluorescein is the sodium salt of commercial
Chrysolin, which dyes wool and silk directly, imparting to them a color resemb-
ling turmeric.

Phosphorus pentachloride converts fluorescein into Fluorescein chloride,
C = (CeH,Cl),0
CgH^- \ (Annalen, 183, 18). Its halogen atoms are very re-

\co.o

active. It is used for the preparation of rhodamine (see below).

C[C,H3(0H),], _

Pyrocatechin-phthalein, C2oH,^Oe ^= CgH^^ \ , is pro-

^CO.O
duced when phthalic anhydride and pyrocatechin are heated to 140-150° with
zinc chloride ^Berichte, 22, 2197). It is a yellow, non-crystallizable mass. It
dissolves in the caustic alkalies with a blue color, in the alkaline carbonates with
a violet color. From its acid esters we would infer the presence of four hydroxyl
groups in it ; hence it does not form an inner anhydride.

Pyrogallol-phthalein, Gallein, CjoHnjO, (see Annalen, 209, 249), is ob-
tained on heating pyrogallic acid with phthalic anhydride to 200°. It dissolves
with a dark red color in alcohol, and with a beautiful blue color in the alkalies.
Zinc dust reduces it tb hydrogallein, C2oHj20,, and then to gallin, Q.^^\\fi^,
which corresponds to phenol-phthalin.

Like all phthalins (p. 880), it is converted by sulphuric acid into the anthracene
derivatives, Coerulin, CjoHj^Og, and Coerulein, CjpHgOg. The latter dissolves
in the alkalies with a green color, and finds application as a green dye.

Chlorinated phthalic acids can be substituted for phthalic acid in the preparation
of the preceding compounds. Various fluoresceins and eosins result. They ac-
quire a violet-red color with the increasing number of halogen atoms {Erythrosin,
Phloxin, etc).

Phthalic anhydride also reacts with dimethylaniline, yielding

,C(C,H,.NR2),

Dimethylaniline-phthalein, C24H2^N202 = C5H^(' \^ . . With

/
^CO.O

phthalyl chloride we get an isomeric body, the so-called Phthal-green, which is
probably a phthalidin, and is derived from anthracene [Annalen, 206, 92).

The phenols can combine with the anhydrides of dibasic fatty acids (oxalic,
succinic, maleic) and with tartaric acid, citric acid, etc. {Berichte, 15, 883, 18,
2864), yielding analogous phthaleins and phthalins. Succinyl fluorescein,
CjgHijOj, from succinic acid and resorcinol, yields a tetrabromderivative,
Ci8lIjBr405, very similar to Eosin.

884

ORGANIC CHEMISTRY.

Rhodamines.

The rhodamines, the phthaleins of m amido phenol, C5H4(NH5,).OH, and its
derivatives, are of special importance. They are violet-red, magnificently fluores-
cent dyestufls. In constitution they are perfectly analogous to the fluoresceins;
they contain two amido groups in place of the two hydroxyls : —

C2oHio03(OH)2
Fluorescein.

,,H.„0,(NH,),
Rhodamine.

They correspond in all particulars to the rosamines (p. 877), and like them con-
tain salt- forming groups of negative and positive nature. The simplest xiio&saixxie.
is formed when m- amidophenol hydrochloride and phthalic anhydride are heated
to 180-190° with sulphuric acid {Berichte, 21, Ref 682): —

/

NH,

C.H,

C,H /^0\o ^ 2C,H /NH, _ c,H,.C^ /O -f 2H,0.

-6"4\CO/

*\0H

L_ I

\

CO— O ^6^3

NH,

The hydrochloride salt forms metallic green leaflets. Its solutions are yellow in
color and highly fluorescent. The alkylic rhodamines possess more intense colors.
They are produced when the salt is heated with alkyl iodides. A better course to
pursue in this preparation is the condensation of alkylic m- amido phenols (p.
681) and phenyl-»z-amido phenol (w2- oxydiphenylamine, p. 603) (Berichte, 21,
Ref. 682, 920; 22, Ref. 788). Still another procedure consists in rearranging
flouresceiu chloride (p. 883) by heating it with dialkylamines (Berichte, 22, Ref.

625,789)-

Succinic acid yields rhodamines.

C,H,. .CeH3.N(CH3)3,

Succino-ihodatnine,
mercial rhodamine S.

'\r/

=\

CO.q/ \c,H3.N(CH3)/

O, is apparently the com-

j. Derivatives with benzene nuclei joined by two or more carbon-
atoms (/. 842).

CgHj.CHg
C15H5.CH2

Dibenzyl.

C„H,.CH.OH

THE DIBENZYL GROUP.
C„H,.CH

Toluylene.

C„H,.CH.OH C„H,.CO

CeHj.C
Tolane.

CjHj.CH.OH

Hydrobenzoi'n.

CgH CO

Benzoin.

CeH^.CO

Benzil.

C.H^.CO

Desoxybenzo'in.

Dibenzyl, Ci^H^ (symmetrical diphenyl ethane), is prepared by
the action of sodium or (copper) upon benzyl chloride, CeHj.'
CH2CI, or of AICI3 upon benzene and ethylene chloride, and by

STILBENE, TOLUYLENE. 885

heating stilbene and tolane, or benzoin and desoxybenzoin with
hydriodic acid. It crystallizes in large prisms, melting at 52°, and
boiling at 284°. It forms stilbene and toluene when heated to
500°. Chromic acid and potassium permanganate oxidize it
directly to benzoic acid.

It yields two dinitro-compounds by nitration.

//-Dinitrodibenzyl, NOj.CeH^.CHj.CH^.CsH^.NO^, has also been obtained
by the action of stannous chloride upon /-nitrobenzyl chloride, NO^.C^H^.
CHjCl. It crystallizes in yellow needles and melts at 179° [Anna/en, 238, 272).
Diamidodibenzyl, H^N.CsH^.CjH^.CgH^.NHj, and its tetramethyl derivative
are, in distinction to the corresponding diphenylmethane derivatives, bases that lack
coloring power [Berichfe, 20, 914).

Stilbene, Toluylene, Ci4Hi2 = CcHj.CHiCH.CoHj, symmetri-
cal diphenyl ethylene, is produced in various ways, thus : by distil-
ling benzyl sulphide and disulphide ; by the action of sodium upon
bitter-almond oil or benzal chloride, CeHj.CHCla; by conduct-
ing dibenzyl or toluene vapors over heated lead oxide ; by heating
diphenyl monochlorethane alone or diphenyl trichlorethane with
zinc dust, by reducing tolane with zinc dust and glacial acetic
acid, or sodium and alcohol. An interesting method for its pro-
duction is that of distilling fumaric and cinnamic phenyl esters
{Berichte, 18, 1945). It crystallizes in large monoclinic leaflets or
prisms, dissolves easily in hot alcohol, melts at 120°, and distils at
306°.

When heated with hydriodic acid it yields dibenzyl, C^j^Hj^. Chromic acid
oxidizes it to bitter-almond oil and benzoic acid. It is immediately attacked by
potassium permanganate, while phenanthrene does not react.

Bromine combines with stilbene, fonning Stilbene Dibromide, CgHj.'CHBr.
CHBr.CgHj, dibromdibenzyl. It is also prepared from dibenzyl by the action of
bromine and from the two hydrobenzoins by means of PBr^. It consists of silky
needles, melting at 237°. Alcoholic potassium hydroxide converts it into brom-
stilbene, (CgHjjjCjHBr (melting at 25°), and then into tolane.

With chlorine, stilbene (in chloroform solution) yields a-Stilbene Chloride,
(Cg 115)202 HjClj, which is also obtained from hydro- and isohydrobenzoin with
PCI5. It melts at 192°. ^S-Stilbene Chloride is produced at the same time
from hydrobenzoin. It melts at 93°, and after heating to 200°, yields the a-com-
pound on crystallizing {^Annalen, 198, 131).

The action of alcoholic potash upon tf-nitrobenzyl chloride (p. 584) gives rise
to two alloisomeric o-Dinitro-stilbenes, (C|5H4.N02)2.C2H2, melting at 126°
and 127°. The first is the maleinoid or cis variety, while the second represents
the trans-ioxm {Berichte, 21, 2071 ; 23, 2073). /-Nitrobenzyl chloride also
yields two aXloisomedc p-Dinitro-sHlbenes (Berichte, 23, 1938). The principal por-
tion of the product melts at 250° (280°), and upon reduction yields //-Diamido-
stilbene, B.^^.C^il^.C^li^.C^}i^.T>iB.^, melting at 227°- It can also be obtained
from /-nitrotoluene by the action of caustic soda and further reduction with stan-
nous chloride {Berichte, ig, 3238). It combines similarly to benzidine with the
naphthol sulphonic acids, forming substantive blue azo-dyes {Berichte, 22, Ref.

886 ORGANIC CHEMISTRY.

Tolane, Ci4Hi„=:C6H5.C=C.C6H5, Diphenyl Acetylene, is pro-
duced from stilbene bromide on boiling with alcoholic potash. It
is easily -soluble in alcohol and ether, and consists of large crystals,
melting at 60°. Chromic acid oxidizes it to benzoic acid.

Two tolane dichlorides, C,jHj„Cl2, result on conducting chlorine into tolane
(in chloroform solution). They can also be prepared by reducing tolane tetra-
chloride with iron and acetic acid {Berichte, 17, 1 165, 833) ; the a- melts at 143°,
the /3- at 63°. The first is supposed to be the plane symmetrical, maleinoid form, the
second the fumaroid form [Annalen, 248, 18). Tolane also yields two dibro-
mides, C^HjoBr^, with bromine, the o- variety melting at 208°, the /3- at 64°.
Both regenerate tolane on treatment with alcoholic potash.

Tolane Tetrachloride, C^^^\, is produced from chlorobenzil (p. 889)
with PCI5, by chlorinating toluene (together with C^Hg.CCI,) and by heating
CgHj.CClg with copper. It consists of brilliant crystals, which become porce-
lanous at 100° and melt at 163°. Heated with sulphuric acid to 165°, or glacial
acetic acid to 200°, it yields benzil.

Hydrobenzoins, CuHiA = C5H5.CH(OH).CH(OH).CeH5.
Toluylene Glycols. Two isomeric bodies — hydrobenzoitn and iso-
hydrobenzoin — are produced when zinc and alcoholic hydrochloric
acid act upon oil of almonds, or when the latter is treated with
sodi-um amalgam. Both are also obtained from stilbene bromide
or chloride, on converting the latter by silver acetate or benzoate
into esters, and saponifying these with alcoholic ammonia. With
potassium acetate, isohydrobenzoin is almost the sole product.
Hydrobenzoin predominates (with a little isohydrobenzoin) when
sodium amalgam acts on benzoin. This is also the best method for
its preparation {Annalen, 248, 36).

PBrj converts both into the same stilbene bromide (melting at 237°) ; and with
PCI5 both yield a-stilbene chloride (the ^-chloride is also produced from hydro-
benzoin). Chromic acid oxidizes both to bitter-almond oil and benzoic acid, but
with nitric acid benzoin and benzil are the products. All these reactions prove
that the two hydrobenzoins possess the same structural formula (see Annalen, 198,
191), and that relations analogous to those observed with the dialkyl succinic
acids, the tolane chlorides, etc., are also present here. Stereochemically considered
hydrobenzoin is the fumaroid, and isohydrobenzoin the malenoid form [Annalen,
258, 186).

Bydrobenzoin dissolves with difficulty in water, is readily soluble in alcohol,
crystallizes in large, shining, rhombic plates, melting at 134° and sublimes without
decomposition. The diacetate, C-^^Yi^O.C^jd\, is obtained from benzaldehyde
and acetyl chloride by means of zinc dust; it consists of large prisms, melting at
134°. Diphenyl aldehyde (p. 861) and hydrobenzoin-anhydride, (C5H,,)2C2H20,
melting at 132° (see Annalen, 258, 186), are produced when hydrobenzoin is
boiled with sulphuric acid (20%).

Isohydrobenzoin is more easily soluble in water than the preceding isomeride.
It crystallizes in shining, four-sided prisms which contain water of crystallization.

BJSJMZUllN. 887

and rapidly effloresce on exposure. It crystallizes from alcohol in an anhydrous
form, and melts at 119.5°. lis diacetate is dimorphous, and crystallizes in shining
leaflets, melting at 1 1 8°, or in rhombic prisms melting at 106°. Isohydrobenzoln,
boiled with sulphuric acid, yields its anhydride, (CjH5)2C2H20, melting at
102° (together with a little diphenyl aldehyde).

Benzoin, CuHi^O., = QH5.CH(OH).CO.C6H5, a ketone alco-
hol, is produced when hydro- and isohydrobenzoln are oxidized
with concentrated nitric acid, and by the action of potassium
cyanide upon benzaldehyde in alcoholic solution {Berichte, 21,
1296) : —

CeH5.CH.OH
2CJH5.CHO = I

CeHj.CO

All aromatic aldehydes afford the latter reaction ; this is also true of furfurol
(p. 524). It is analogous to the condensation of the ketones to pinacones
(p. 202) and to the conversion of aldehydes into alcohols and acids by alcoholic
potash. The products are termed benzoins, and are capable of reducing Fehling's
solution, even at ordinary temperatures, when they are oxidized' to benzils
(diketones).

Benzoin dissolves with difficulty in water, cold alcohol and ether ; it crystallizes
in shining prisms, and melts at 134°. Nascent hydrogen converts it into hydro-
benzoin. When its alcoholic solution is digested with phenylhydrazine it forms
the hydrazone, Cj^Hj20(N2H.C5H5), melting at 155°. When oxidized with
chromic acid, it breaks up into benzaldehyde and benzoic acid. Hydrobenzoin
and benzil (along with benzilic acid) are produced on boiling with alcoholic
potash : —

C5H5.CH.OH CeH..CH.OH CeHj.CO

2 I = I + I •

CgHs.CO CeH^.CH.OH CeH^.CO

Benzoin. Hydrobenzoin. Benzil.

Anisoin, from anisic aldehyde, and cuminoin, from cumin aldehyde, are very
similar to benzoin, and yield perfectly analogous derivatives (desoxybenzoTns,
benzils and benzilic acids) (^Berichte, 14, 323). CSClj converts the benzoins into
beautifully colored compounds, called desaurines {Berichte, 21, 2445).

Desoxybenzoin, Cj^H^jO = CjHj.CO.CH^.CgHj, phenyl-benzyl ketone, is
obtained by rfeducing benzoin or chlorobenzil, CgH5.CO.CCl2.CgH5, with zinc and
hydrochloric acid; by heating monobromtoluylene with water to 180-190°; by
distilling a mixture of calcium benzoate and calcium phenyl-acetate : —

CjHj.CO.OH +C5H5.CHjCO.OH = ^6H6.CO \ _|. ^Qj + Hp;

further, when AICI3 acts upon a mixture of alphatoluic chloride, C5H5.CHj.CO.Cl
and benzene {Berichte, ig, 1064) ; and most easily by the reduction of ben-
zoin with zinc and hydrochloric acid {Berichte, 21, 1296).

Phenyl benzyl ketone crystallizes from alcohol in large plates, melting at 60°
and boiling at 314°- One H-atom of its CHj-gjoup can be replaced by sodium
and alkyls, but not the second {Berichte, 21, 1297 ; 23, 2071). Nitrous acid, or
amyl nitrite, converts it into isonitroso-Atso'^yhenzom, melting at 135°, and identi-
cal with benzil monoxime (see below). It forms an oxime, melting at 98°, with
hydroxylamine. Bromine converts desoxybenzoin into Desylbromide, (CjHj)^
C,HBrO, melting at 55° {Berichte, 21, 1355). It yields dibenzyl when heated

888 ORGANIC CHEMISTRY.

with hydriodic acid. Sodium amalgam converts it into toluylene hydrate, ^^^-^fi ^=
CgH5.CH(OH).CH2.C5H5, melting at 62°. Nitric acid again oxidizes it to desoxy-
benzoin. See Berichte, 22, 1229, for methyl desoxybenzoins.

Benzil, C14H10O2 = CeHj.CO.CO.CeHj, Dibenzoyl, an o-dike-
tone, is produced in the oxidation of benzoin with chlorine ; and by
heating toluylene bromide with water and silver oxide (together with
toluylene). It crystallizes from ether in large, six-sided prisms,
melting at 90° and boiling at 347°.

Benzil-dihydrazone, (CgH5)2C2(N2H.CgH5)j, is produced on digesting phenyl-
hydrazine hydrochloride and benzil. It melts at 225° (Annalen, 232, 230). It
forms triphenyl-osotriazone when heated to 210° (p. SS3). An isomeric dihydra-
zone has not been prepared (Berichte, 21, 2806).

One molecule of hydroxylamine, acting upon benzil, produces two alloisomeric
C5H5.CO
benzil-monoximes, ■ , the a- melting at 138°, and the y- at 114°.

CgHj.CiN.OH

The former passes into the latter by heating it to 100° with alcohol, or upon dis-
solving it in glacial acetic acid with hydrochloric acid. a-Monoxime and hydroxyl-
amine form a-benzil dioxime, while the 7-monoxime yields y-benzil-dioxime. The
expected /3-benzil monoxime has not been discovered (Berichte, 22, 540, 709).
See Berichte, 22, 1998, for the benzyl ethers of the benzil monoximes.

Two molecules of hydroxylamine convert benzil into two alloisomeric benzil
CeHj.CN.OH
dioximes, | , the a- melting at 237°, and the ^- at 207°. A third

CsHj.ON.OH
y-benzil dioxime has been prepared from ^benzil monoxime and hydroxylamine
(see above); it melts below 100°, loses its water of crystallization, and then re-
melts at 164-166°, passing at the same time into the /J-dioxime (Berichte, 22,709).
When the three dioximes are heated to 100° with hydrochloric acid, they are re-
solved into 2NH2.OH and benzil. They yield three different diacidyl esters with
acid anhydrides. By elimination of water they all form the same anhydride,
(C^^fi^jd, melting at 94°. Potassium ferricyanide, in alkaline solution, oxid-
izes all three to the same oxide, (CgHj)^^^ piivj n>. melting at 1 14°; when rap-
idly distilled, it becomes phenyl-cyanate. Carbanilido-derivatives are produced
by the union of the three benzil dioximes with phenyl-cyanate (Berichte, 22, 3 1 1 1 ).
Glacial acetic acid and hydrochloric acid acting upon j8-benzil dioxime rearranges
it to oxanilide, CsH5.NH.CO.CO.NH.CgH5 (see benzophenoxime, p. 858),
whereas a-benzil dioxime yields dibenzenyl azoxime (p. 718) (Berichte, 22, Ref

592)-

Far-reaching theories, based on van't Hoff 's ideas have been proposed to ex-
plain the differences in the three structurally identical benzil dioximes (Berichte,
21, 946, 3510 ; 22, 705) ; but they have proved insufificient (Berichte, 23, 2405).
At the present writing the inclination is to refer the isomerism to the nitrogen atom
of the hydroxylamine (p. 719). It has been attempted to construct theories of
great import upon very few facts.* Chromic acid oxidizes it -to benzoic acid.

When benzil is allowed to stand for some time, with alcohols and some potas-
sium cyanide, it sustains a decoinposition into benzoic ester and benzaldehyde,
which further changes to benzoic acid, Furil, but not isatin, reacts similarly.

*" Hypotheses non fingo." — Newton,

DIBKNZYL CARBOXYLIC ACID. 889

When digested with PCI5 benzil yields chlorobenzil, C5H5.CO.CCI2.C1.H5,
melting at 61°. Benzil, when heated with alcoholic potash, is converted into ben-
zilic acid (p. 862). In this case a molecular rearrangement takes place similar to
that observed with the pinacones.

Isobenzil, C^HijOj, is isomeric with the preceding, and is obtained from ben-
zoyl chloride, CgH5.CO.Cl, in alcoholic solution, by means of sodium amalgam.
It forms, in distinction to benzil, jW/^/Z^ needles, melting at 156° and boiling at 314°.
It forms /3-benzil dioxime with hydroxylamine [Berichte, 21, 808).

Anisil, (CH3.0.CgH^).^C202, from anisotn and cuminil, {C^^.C^lA^fifi^,
from cuminoin (above), behave like benzil. When they are boiled or fused with
caustic potash, they afford anisilic acid, (CH3.0.C5H^)2C(OH).C02H, and
cuminilic acid, (C^^.C^^^QiOYVj.CO,^. Anisil forms two dioximes with
hydroxylamine {Berichte, Z2, 372). <

Pinacones and Pinacolines.

Nascent hydrogen, acting on the benzo-ketones, converts them, through a con-
densation of two molecules, into the pinacones (together with slight quantities of
the secondary alcohols), which are also bivalent alcohols (glycols). In this
behavior they resemble the ketones of the fatty series (p. 202). From benzo-
phenone we get benzhydrol (p. 857) and benzpinacone : —

(C,H5),C.OH
(CgHJjCO yields (C6H5)2CH.OH and |

Benzophenone. Benzhydrol. (CgH5)2C.OH

Benzpmacone.

These pinacones, just like those of the fatty series, readily part with water (by
heating with sulphuric or hydrochloric acid, or by the action of all reagents, which
otherwise act upon hydroxyl — acetyl chloride, hydriodic acid and PCI5) and by an
atomic rearrangement \xcome pinacoline ketones : —

(CeH5)2.C.OH

yields (C(jH5)3C.CO.CsH5 + H^O.
(C(;H5)2.C.OH Benzpinacolinc.

An analogous change occurs in the conversion of benzil into benzilic acid (see
above), and of pheuanthraquinone into diphenylene glycollic acid (p. 85 1 ). There-
fore, the conception of the pinacone bodies may be further extended to all alco-
hols having two adjacent OH-groups (conip. Annalen, ig8, 144).

Benzpinacone, C^gHj^Oj, formed from benzophenone by the action of zinc
and sulphuric acid {Berichte, 14, 1402), crystallizes from alcohol in shining, small
prisms, melting at 185° and splitting into benzophenone and benzhydrol. It sus-
tains a like change when boiled with alcoholic potash.

On heating benzpinacone with hydrochloric or dilute sulphuric acid to 200°,
by the action of methyl chloride upon it, or of zinc dust and acetyl chloride upon
benzophenone, we get two

Benzpinacolines, CjgH^oO — the a-, melting at 205°, the ;8-variety, at 179°
[Berichte, 17, 912). Both decompose into triphenyl methane, (0^115)3011, and
benzoic acid, on boiling with alcoholic potash.

Carboxyl Derivatives.

CgHg.OHg
Dibenzyl Carboxylic Acid, ■ , Benzylphenyl Acetic Acid, re-

CeH5.CH.OO2H
suits upon introducing benzyl into benzyl cyanide, etc. It melts at 91°, and boils
about 335° (^Berichte, 21, 1315).

/

890 ORGANIC CHEMISTRY.

Diphenyl Acrylic Acid, a-Phenyl Cinnamic Acid, C5H5.CH:C(CgH5).
COjH, formed by the condensation of phenyl-acetic acid, CgHj.CHj.COjH,
with benzaldehyde, melts at 170°. Sodium amalgam converts it into dibenzyl
carboxylic acid.

o-Benzil Carboxylic Acid, C8H5.CO.CO.CgH4.CO2H, exists in two alloiso-
meric forms, resulting from the oxidation of desoxybenzo'in carboxylic acid. The
yellow colorei modification melts at 1AI° , ihe white at 125-130°. Both afford
the same ethyl ester, and the same monoxime (melting at 160°) [Berichte, 23,
1344, 2079).

D-Desoxybenzoin Carboxylic Acid, CgHj.CHj.CO.C^H^.COjH, may be
obtained by boiling benzylidene phthalide with alkalies. It crystallizes with one
molecule of water, and melts at 75°. The corresponding lactone, Benzylidene

^C ;:= CH.CgHg
Phthalide, C-H.^ \ (see p. 352), results from the condensation of

^CO.O
phthalic anhydride with phenyl-acetic acid [Berichte, 18, 3470). It melts at 99°.
It forms salts of desoxybenzoin carboxylic acid when boiled with alkalies.

Dicarboxylic Acids.

Diphenyl-succinic Acid, CuHj^O^, Dibenzyl-dicarboxylic Acid, occurs,
similarly to the dialkyl succinic acids (p. 419) and hydrobenzoin, in two alloiso-
meric forms. The a-acid is produced on heating phenyl-brom acetic acid with
alcoholic CNK [Berichte, 23, 117), also (together with the ^-acid), from the
anhydride of stilbene dicarboxylic acid (Berichte, 14, 1802; Annalen, 259, 61).
Its dinitrile, (C5H5)2C2H2(CN)2, is obtained from phenyl-brom-acetonitrile with
potassium cyanide. The acid crystaUizes from water in prisms, containing one
molecule of water, melts at 185° when rapidly heated, loses water and remelts at
220°. When heated to 200° with hydrochloric acid it changes to the /3-acid. Its
anhydride, melting at 116°, is readily produced by means of acetyl chloride.

The isomeric /3-Dibenzyl-dicarboxylic Acid is produced from the anhydride
of stilbene dicarboxylic acid with sodium amalgam ; and from dicyan stilbene,
(C|.Hj)2C2(CN)2, when heated with sodium amalgam or when heated with
hydrochloric acid. It is insoluble in water and melts at 229°, when it yields
water and the anhydride of the a-acid. It also yields the anhydride (but with
more difficulty) when heated with acetyl chloride {Berichte, 23, Ref. 574, 646).
It melts at 112°.

C5H5.C.CO2H

Stilbene Dicarboxylic Acid, C^sHijO^ = || , if separated from

CgH^.C.COjH
its salts, at once decomposes into water and its anhydride, melting at I5S°. The
nitiile, (C ^^^ ^^^{C^\, dicyanstilbene, is derived from phenyl-brom-acetic nitrile,
C5H5.CHBr.CN [Berichte, 14, 1797), with alcoholic potassium cyanide. It
melts at 158°. It passes into salts of stilbene dicarboxylic acid when boiled with
alkalies.

Diphthalyl Acid, HCOj.CgHt.CO.CO.CjH^.COjH, oo-Benzil-dicarboxylic
Acidj from diphthalyl by oxidation, or by the action of zinc dust and acetic acid
upon phthalic _ anhydride and further oxidation [Berichte, 21, Ref. 7) is only
known in a single white modification (see benzylic acid), melting at 270°. It
however, yields two series of dialkyl esters, white and yellow colored [Berichte,
23. 1347. 2080). It forms the anhydride, CjjHgOj, when heated to 200° with
acetic anhydride; it melts at 165° When heated with hydriodic acid it is reduced

to Diphthalyl, OC^^^^^^ = "xi^^^^CO, which may be obtained by the

condensation of phthalic anhydride with phthalide (p. 772), aided by sodium
acetate. It melts at 334° [Berichte, 19, Ref. 695).

DIPHENACYL, DIBENZOYL ETHANE. 89 1

Tetraphenyl Ethane, C^^H,^ = (C6H5)2CH.CH(CeH5)2, is obtained from
benzophenone by heating with zinc dust (along with diphenyl methane and tetra-
phenyl-ethylene) ; from benzpinacone and benzpinacoline with hydriodic acid and
phosphorus ; from benzhydrol chloride, (Cg H5)2CHCI, by the action of zinc ; from
teti-aphenyl ethylene by sodium and alcohol, and from tetrabromethane or stilbene
bromide by means of benzene and AICI3 [Berichte, 18, 657). It crystallizes from
acetic acid or benzene in large prisms, melting at 209°.

Tetraphenyl Ethylene, ^Z^^^i^^ = {C^Yi^\Z:Q,{Z^YL^\, formed together
with tetraphenyl ethane, from benzophenone, is also obtained on heating benzo-
phenone chloride, (CgH5)2CCl2, with silver. It crystallizes from benzene in tine
needles, melting at 221°. Both hydrocarbons are split into two molecules of
benzophenone when oxidized.

(CeH5),C.CN

Tetraphenyl Ethylene Cyanide, • , is obtained from diphenyl-

(C,H5),C.CN
acetic nitrile (p. 861) by means of metallic sodium and iodine [Berichte, 22,
1227). Its acid, tetraphenyl-succinic acid, {C.^^)^Q,^((ZO^W)^, has been ob-
tained from diphenyl chloracetic ester and melts at 261°.

Derivatives, containing benzene nuclei linked by a chain of three or. four carbon
atoms, are : —

Dibenzyl Ketone, (CgH5.CH2)2CO, produced on distilling calcium alpha-
toluate ; it melts at 30° and boils at 320°. It forms an oxime with hydioxy-
lamine, melting at 119°. One hydrogen atom of each of the two CHj-groups can
be replaced by alkyls [Berichte, 21, 1317). When reduced with hydriodic acid it
forms Dibenzyl methane, (CgH5.CH2)2CH2, boiling at 290-300°.

Dibenzoyl Methane, (CgHj COj^CH,, is formed upon boiling dibenzoyl acetic
acid with water. It crystallizes in large plates, melting at 8 1°, and distilling without
decomposition [Berichte, 20, 655). The rearrangement of its isonitroso derivative,
(CgHj.COjjCiN.OH, or its bromide, results in the production of

Diphenyl Triketone, C5H5.CO.CO.CO.CgH5. A brown oil, boiling at 289°
(175 mm. pressure). It solidifies to a golden yellow mass, melting at 70°. In the
air it combines with water to a colorless hydrate [Berichte, 23, 3378).

Tribenzoyl Methane, (CgH5.CO)3CH, obtained from dibenzoyl methane and
benzoyl chloride with sodiurn ethylate, melts at 225°. It does not possess acid
properties (see dibenzoyl acetone (p. 731) [Berichte, 21, 1153)-

Dibenzyl Acetic Acid, (C5H5.CH2)2.CH.C02H, is derived from dibenzoyl-
malonic acid. It melts at 87°, and is insoluble in water. Its nitrile melts at 90° ;
its CH-group cannot be substituted [Berichte, 2, 1328).

Dibenzyl GlycoUic Acid, CigHigOs = (C|iHg.CH2)2C(OH).C02H, Oxa-
tolylic Acid, is produced from dibenzyl ketone by means of CNK and hydro-
chloric acid, and when vulpic and pulvic acids are boiled with> dilute alkalies. It
is almost insoluble in water, and crystallizes from alcohol in prisms, melting at
156°. When boiled with concentrated potassium hydroxide it decomposes into
oxalic acid and two molecules of toluene [Annalen, 2ig, 41).

Dibenzoyl Acetic Acid, (C5H5.CO)2CH.C02H (p. 765), breaks down into
dibenzoyl methane.

CeH5.CO.CH2
Diphenacyl, • , Dibenzoyl Ethane, is produced by the decom-

CgH5.CO.CH2
position of phenacyl-benzoyl acetic ester (p. 765). It consists of needles, melting
at 145° [Berichte, 21, 3056). Being a /-diketone it can ehminate water and yield

892 ORGANIC CHEMISTRY.

diphenylfurfurane, and with P2S5 form diphenylthiophene, and with ammonia
diphenylpyrrol (p. 73' )■

C,H,.COCH.C,H,

Bidesyl, I , dibenzoyl-diphenyl ethane, results when desyl-

CeHs.CO.CH.CeH,
bromide acts upon sodium desoxybenzoin (p. 887). It crystallizes from hot
benzene, in needles, melting at 255°. Jsobidesyl, formed simultaneously, melts at
161° [Berichte, 21, 1355). Bidesyl is identical with hydro-oxy-lepidene. Bidesyl
and isobidesyl, being 7-diketones, form tetraphenyl pyrrol (p. 543) when heated
with ammpnia. Concentrated hydrochloric acid converts them into tetraphenyl
furfurane, C,(CsH,),0 (p. 524) with lepidene {Berichte, 22, 855, 2880).

CsH^.CO.CH.CO^H

Dibenzoyl Succinic Acid, CjgH,,0„ = | .Its diethyl

QHj.CO.CH.CO^H
ester is obtained from sodium benzoyl acetic ester (p. 763) by the action of iodine,
just as we form di-aceto-succinic ester from aceto-acetic ester. On boiling the
ester with dilute sulphuric acid we get (by saponification and elimination of
water) its anhydride the mono-lactone CjjHjjOj (corresponding to carbopyro-
tritartaric acid), which very probably represents diphenyl-furfurane dicarboxylic
ester.

Vulpic Acid,CjgHm05, is intimately related to dibenzyl acetic acid, and oc-
curs in the lichen Cetraria vtilpina and in a certain moss (12 per cent.), from
which it may be extracted by chloroform or lime water. It is sparingly soluble
in water and ether, crystallizes from alcohol in yellow prisms, melting at H0° and
subliming. When boiled with lime water it is converted into methyl alcohol and
pulvic acid, Cj jHjjOj. The latter melts at 214°, and when boiled with alkalies
yields 2CO2 and dibenzyl glycoUic acid. When boiled with ammonia and zinc
dust it forms Hydrocornicularic Acid, CjjHjgOj. This breaks down into toluene
and phenyl succinic acid when heated with caustic potash [Berichte, 14, 1686).

Diphenacyl Malonic Ester, (CjH5.CO.CH2)C(C02R)2, is produced by the
interaction of acetophenone bromide and sodmalonic ester. The free acid loses
carbon dioxide and forms Diphenacyl Acetic Acid, (CgH5.CO.CH2)2CH.C02H,
which by the action of ammonia and the production of a closed ring by the group
CO.CHj.CHR.CHj.CO, yields d.\'piitn.y\ pyridine carboxylic acid.

ANTHRACENE GROUP.

The members of this group contain two benzene nuclei, joined
to each other by two doubly united carbon-atoms. In each ben-
zene nucleus two ortho-positions are occupied. Therefore, we may
designate them Diortho-diphenylene Derivatives (p. 850) ; usually,
however, their names are derived from anthracene, from which
they were first obtained : —

/CH2. CO CH

^CHj/ ^CO'^ ^CH-^

Diphenylene Dimethylene Diphenylene Diketone Anthracene.

Hydranthracene. Anthraquinone.

Hydranthracene passes readily into anthracene by the loss of two
hydrogen atoms ; whereby we may suppose a mutual union of the

"* ANTHRACENE GROUP. 893

. J

two methane carbons takes place. Therefore, anthracene is mostly
formed by its synthetic methods. Of the numerous syntheses of
anthracene and diphenylene derivatives, analogous to those of the
diphenyl methane derivatives (comp. p. 852), only such will be
noticed, as are necessary for the establishment of the constitution
of the compounds.

Hydranthracene is obtained from ortho-brom-berzyl bromide, CgH^Br.CHjBr,
by the action of sodium upon the ethereal solution ; the bromine atoms of two
molecules are withdrawn, and the residues combine {Berichte, 12, 1965) : —

CeH,/^^^^' + BrCHl>C6H, + 4Na = C,n,(^-\c,n, + 4NaBr;

Two molecules. ^c-Brombenzyl- Hydranthracene,

bromide.

at the same time two hydrogen-atoms separate from the hydranthracene and large
quantities of anthracene are produced.

Anthracene is likewise obtained (together with toluene) from benzyl chloride,
on heating it with aluminium chloride : —

CH
3C,H,.CH,.C1 = C,H,/ I \C,H, + C.H^.CH, + 3HCI,

or with water to 200°, when dibenzyl will also be produced : —

4C,H5.CH,a = Ci,Hi„ + (CeH^.CH,), + 4HCI.

Anthracene (together with diphenyl methane) results also from the action of
AICI3 upon benzene and CH2CI2 (2 molecules).

A noteworthy synthetic method is that from benzene and symrnetrical tetrabrom-
methane with AICI3 {Berichte, 16, 623) : —

BrCHBr ' CH,

C6H6+ I +CeH, =C5H/| ^CsH, + 4HBr.

BrCHBr - ^CH-^

Dimethylanthracene hydride, CeH^<^(-,jjLjj3|\CgH^, is similarly formed

from benzene and ethidene chloride or bromide.

The formation of anthraquinone or diphenylene dilietone from phthalic chloride
and benzene, by heating with zinc dust to 200°, is very evident : —

-CO.Cl CO.

CsHiCT +CeH, = C,h/ )CeH^ + 2HCI;

\co.ci ^cq/

as well as its production from ortho-benzoyl benzoic acid when the latter is heated
with phosphoric anhydride {Berichte, 7, 578) : —

.CO.CeHj .CO.

C,h/ =CeH/ )C,H, + H,0;

^CO.OH -^CQ/

and by the distillation of calcium phthalate. In this manner the homologous
alkyl anthraquinones are obtained from the homologous o-benzoyl benzoic acids.

o-Benzoyl benzoic acid is directly converted into anthracene upon heating it
with zinc dust, and o-toluyl benzoic acid (p. 864) yields /3-methyl anthracene
{Berichte, 19, Ref. 686).

894 ORGANIC CHEMISTRY

/

Again, when o-tolyl-phenyl ketone, CgH^c'^^CeHs (p. 862), is heated

with lead oxide, anthraquinone is produced. If zinc dust be employed anthra-
cene results. In the same manner anthracene is formed from orthotolyl-phenyl
methane, C6H4(CH3).CHj.C5H5, and methyl anthracene, etc., from o-ditolyl-
methane, C5H^(CH3).CH2.CeHi.CH3, etc. {Berichte, 23, Ref 198).

It follows from all these syntheses (by means of ortho-derivatives of benzene),
that in one of the benzene nuclei of anthracene and its derivatives, the two carbon-
atoms are inserted in the ortho-position ; that this is true, too, of the second nucleus
is inferred from the production of anthracene and its hydride from o-brom-benzyl
bromide (p. 893) ; also from the behavior of oxanthraquinone, C^^.{Oy)jZ^Yi.^.
OH, which is synthesized from brom-ortho-benzoyl benzoic acid, CjHj.CO.
CjHjBr.COjH (from brom-phthalic acid), and when oxidized (the second
benzene rmcleus being destroyed) yields phthalic acid, C5H^(C02H)2 [Berichte,
12, 2124).

Therefore, anthracene and its derivatives possess a symmetrical constitution,
corresponding to the symbols : —

^ CO '

II II

^\/\r-„/\/^ S/XCO/"^/^

5 4 5^4

Anthracene. Anthraquinone.

in which the numbers designate the eight affinities of the two benzene nuclei.
The positions i, 4, 5, 8 are alike, also 2, 3, 6, 7 ; the former (as with naphthalene,
see this) are called the a-, the latter the /3-positions. We conclude, then, that if
one hydrogen atom of the benzene ring be replaced two isomeric mono-derivatives
(a and /3) of anthracene and anthraquinone can be formed ; whereas by the
entrance of two similar substituting groups ten isomeric di-derivatives result
(p. 898). By the replacement of the middle hydrogen atoms of anthracene other
isomerides are obtained, which have been termed 7-derivatives or ?««o-derivatives
{Berichte, 18, 690).

The two intermediate carbon atoms of anthracene form, with two carbon atoms
from each of the two benzene nuclei, a closed chain consisting of six carbon atoms.
It resembles the ring of benzene. Hence anthracene is included among the con-
densed benzenes (see naphthalene). In most of the transformations of anthracene
the intermediate carbon atoms are first attacked.

Anthracene, C14H10, is formed, in addition to the syntheses
given, from many carbon compounds when they are exposed to a
high heat, and for that reason it is produced in larger quantities in
coal-tar.

-" PJtt'anthracene is obtained from the commercial product (boiling at 340-360°)
by cifystallization from hot xylene and alcohol, or by extraction with acetic ester
or carbon disulphide [Anna/en, igi, 288) ; but better by crystallization from pyri-
dine {Berichte, 21, Ref. 75). Or, hydranthranol is first obtained from anthraquinone
(p. 896) and then boiled with water {Journ.prac. Chemie,Z2ii '46; Berichte, 18,
3034)-

ANTHRACKNE. 89S

Anthracene crystallizes in colorless monoclinic tables, showing a
beautiful blue fluorescence. It dissolves with difficulty in alcohol
and ether, but easily in hot benzene. It melts at 213°, and
distils above 360°. Picric acid in benzene solution unites with
it, yielding CuHio.2C6H3(N02)30, crystallizing in red needles, and
melting at 170°.

When the cold saturated solution of anthracene in benzene is exposed to sun-
light, a modification of anthracene, Para- anthracene, Cj^Hj^, separates out in
plates. It dissolves with . difficulty in benzene, is not attacked by nitric acid or
bromine, melts at 244°, and in so doing reverts to common anthracene.

Anthracene Dihydride, CjjHij, results from the action of sodium amalgam
upon the alcoholic solution of anthracene. It melts at 107°, and boils at 305°.
When heated with hydriodic acid and amorphous phosphorus to 220° Anthra-
cene hexahydride, CijHu, results. It melts at 63°, and boils at 290°. Anthra-
cene perhydride, Ci^H24, is another product. It melts at 88°, and boils at
270° {Berichte, 21,2510).

Mono- and di-halogen anthracenes are obtained when chlorine and bromine
act upon anthracene (in CSj solution). The two middle carbon atoms are substi-
tuted. Nitroanthracene could not be obtained. Nitric acid (concentrated and
diluted, and also in alcoholic solution) oxidizes it to anthraquinone and dinitro-
anthraquinope.

/3-Amido-anthracene, C14H9.NH2, called anthramine, is formed on heating
/i(-anthrol (see below) with alcoholic ammonia to 170°. It forms yellow leaflets,
melting at 237°. Meso-amido-anthracene, C^'H.^{C^'R.'^}ii2)Ci^a^, is pre-
pared by heating anthranol with ammonia. Golden yellow leaflets, decomposing
at 115° {Berichte, 23, 2523).

When anthracene is dissolved in sulphuric acid two Disulphonic Acids,
Cj4Hg(SOjH)2 {a and;3), are produced. These, fused with caustic potash, yield
two dioxy-anthracenes and also the corresponding dioxyanthraquinones.

Oxy-anthracenes, Cj^Hg.OH : —

•CH.
CeH / I )CeH,.OH and C^H/ { ' )C,

CH .qoH)

Anthrol. Anthranol.

Two isomeric compounds (a and /?) correspond to the first formula ; they are
phenols and are called anthrols. yS-Anthrol has been obtained from anthracene-
sulphonic acid (from ;3-anthraquinone sulphonic acid) and by the reduction of
oxyanthraquinone. It crystallizes in leaflets, dissolving with a yellow color in the
alkalies, and in sulphuric acid with a blue color when heated. After the intro-
duction of the acetyl group in OH (compare oxidation of phenols, p. 686) chromic
acid and acetic acid oxidize it to oxyanthraquinone.

Anthranol has the second formula; it is produced ty the careful reduction of
anthraquinone with tin and acetic acid (Berichte, 20, 1854). It crystallizes from
alcohol in shining needles, melting with decomposition at 165°. Chro^:; acid
oxidizes it to anthraquinone. Hydroxylamine converts it into anthraquinoneSexime
[Berichte, 20, 613). For additional derivatives see Berichte, 21, 1176.

The reduction of anthraquinone with zinc dust yields

Hydranthranol, C ^Vi. ^(^^^^'^^C ^^^ ^, and CeH,/^^^0")\ CgH^,

896 ORGANIC CHEMISTRY.

Oxanthranol. These form alkyl compounds with caustic potash and the alkylo-
gens [Berichte, 18, 2150) : —

• C,H/^^JOf)>C,H, and C.H,<C'^gH)>C.H,.

Alkyl Hydranthranols. Alkyl-oxanthranols.

The former, when boiled with hydrochloric acid, part with water and yield
CR
alkyl anthracenes, CgH^;' | ^CgH^; the latter are also reduced to alkyl

anthracenes by zinc dust, but with hydriodic acid' to alkyl anthrahydrides,

C.H^/^I^^^CeH^, etc. {Annalen, 212, 67).

Derivatives of anthranol, in which the hydrogen of the CH-group is replaced
hy phenyls, are the so-caWed. phlkalidins and appear on mixing the triphenyl-car-
boxylic acids with sulphuric acid (p. 880). When oxidized they pass into phenyl-

oxantbranols, C^B.^(^^^^'yC^n^ (the phthalidelns) and yield phenyl

anthracene (p. 901), if ignited with zinc dust. Phenyl anthranol resembles
anthranol, and melts at 141-144°. Benzyloxanthranol is described in Berichte,
23, 2527.

Dioxyanthracenes, C,(|H8(OH)2. Of the ten possible isomeric diphenols
(pp. 894 and 898), two with the formula, HO.CgHj.C^Hj.CjHj.OH, have been
derived from the two anthracene disulphonic acids by fusion with caustic potash.
By oxidizing their acetates with chromic acid (see above) and saponifying, they
yield the corresponding dioxyanthraquinones ; the /3-compound (called chrysazol)
yields chrysazin, the a-compound (rufol) anthrarufin (p. 900). A third (called
Jlavof) is obtained from ^-anthraquinone-disulphonic acid.

Anthraquinone, CuHgOj = CsHJ^. C2O2. CsH,,, Diphenylene di-
ketone (p. 892), is produced very readily, in addition to the synthetic
methods given, by oxidizing anthracene, anthrahydride, dichlor- and
dibrom-anthracene with nitric or chromic acid. We can obtain it by
adding pulverized potassium bichromate to a hot glacial acetic acid
solution of anthracene {Annalen, Sup., 7, 285) or ^yith less expense
by oxidation with the theoretical amount of a chromic acid mixture.

Anthraquinone sublimes in yellow needles, melting at 277°, and
is soluble in hot benzene and nitric acid. It is very stable, and is
altered with difficulty by oxidizing agents. Sulphurous acid does
not reduce it (unlike the true quinones, v. p. 698).

It reverts to anthracene if heated to 150° with hydriodic acid, or with zinc dust,
and ammonia. When fused with potassium hydroxide (at 250°), it decomposes
into two molecules of benzoic acid ; heated with soda-lime it yields benzene and
a little diphenyl. By its union with one molecule of hydroxylamine it forms an-
thraquinone-oxime, Cj^HjO(N.OH), subliming at 200°.

When anthraquinone is digested with bromine at 100° it becomes Dibrom-
anthraquinone, Ci^HgBrjOj, subliming in yellow needles. It is more easily
obtained by oxidizing with nitric acid ; dichloranthraquinone is similarly formed.

OXYANTHRAQUINONES. 897

It yields alizarin if heated to 160° with caustic potash. A monobrom -anthra-
quinone (j8) has been obtained from triBrom-anthracene by oxidation, and melts
at 187°.

Dinitroanthraquinone, Ci4H5(N02)202, is formed (with anthraquinone)
on digesting anthracene with dilute nitric acid (l part with 3 parts water). It
consists of yellow needles or leaflets, melting at 280°, and like picric acid mani-
fests the property of forming crystalline combinations (Fritsche's Reagent) with
many hydrocarbons. The mononitroquinone is obtained when anthraquinone is
boiled with concentrated nitric acid. It is a light yellow powder, melting at 230°
(Berichte, 16, 363). Various dyes are obtained from it through the action of sul-
phuric acid (Berichie, 17, 891).

Heated to 250-260° with concentrated sulphuric acid anthraquinone yields ^-
Anthraquinone-mono-sulphonic acid, Cj^HyOj.SOjH, which crystallizes
from water in yellow leaflets; fused with potassium hydroxide it forms oxanthra-
quinone. Protracted heating with 4-5 parts sulphuric acid yields two disul-
phonic acids, Ci^Hg02(S03H)2 (aand/3). The first may be synthesized by
heating o-benzoyl benzoic acid (p. 863) with fuming sulphuric acid. Fused with
potassium hydroxide it yields anthraflavic acid (2OH) and flav6purpurin (3OM),
while the second furnishes isoanthraflavic acid (2OH) and anthrapurpurln (3OH).
Two isomeric Anthraquinone-disulphonic Acids (7 and 6) are obtained from
the two anthracene-disulphonic acids by oxidation with nitric aeid, and if fused
with caustic potash yield chrysazin and anthrarufin ; trioxyquinone is produced si-
multaneously, together with oxychrysazin and oxyanthrarufin (p. 898).

Anthraquinone is reduced, when digested with zinc dust and an alkaline hy-
droxide, to

C(OH)

Anthrahydroquinone, C.H.f I ^CgH^, which is precipitated in yel-

\C(OH)/
low flakes by hydrochloric acid. If exposed to the air it again oxidizes to anthra-
quinone.

The Oxyanthraquinones, corresponding to the phenols, are
derived by introducing hydroxyl into anthraquinone. There are
two mono-oxy-anthraquinones, CsHi.CjOj.CeHs.OH (a and /9) and
ten dioxy-anthraquinones (p. 894) ; the latter are important as
dyes. They originate from the brom (chlor) anthraquinones and
the sulphonic acids on fusion with alkalies, when the substituting
groups are replaced by hydroxyls.

By stronger fusion there generally ensues an additional entrance of hydroxyl
(oxy- and dioxyanthraquinones result from the mono-sulphonic acid) ; the same
.is true in the fusion of the oxy-quinones — but, as it appears, this is only true for
those derivatives which contain but one hydroxyl in each benzene nucleus
(Berichte, II, 1613).

The oxyanthraquinones (like anthraquinone) may be synthetically prepared on
heating phthalic anhydride with phenols (mono- and pply-valent) and sulphuric
acid to 150° (p. 881) ; —

CoH.,(co)° + CsHU0H)2 = C,H,/CO\c^H2(OH)2 + H2O.

Pyrocatechin (i, 2). Alizarin (i, 2).

75

898 ORGANIC CHEMISTRY.

The di- and tetra-oxyquinones are also produced from the oxy- and dioxyben-
zoic acids, when heated with sulphuric acid, but it seems only the meta deriva-
tives are reactive [Berichie, 18, 2142). Metaoxy benzoic acid yields three dioxy-
anthraquinones : —

2CeH^(OH).C02H = HO.CsHs/^^^qHg.OH + zHfi.

Metaoxybenzoic Acid. Dioxyanthraquinone.

Continued fusion with alkalies causes the oxyanthraquinones to separate into
their component oxybenzoic acids (same as anthraquinone decomposes into ben-
zoic acid) and this reaction aids in the determination of the position of the iso-
merides {Berichte, 12, 1293).

Individual hydroxyls in the oxyanthraquinones are reduced by heating the latter
with stannous chloride and sodmm hydroxide (Anna/en, 183, 216). Heated to
150-200° with ammonia water single OH-groups are replaced by amide groups;
these are further eliminated by diazotizing {Annalen, 183, 202). All anthra-
quinones are reduced to anthracene when heated with zinc dust.

Oxyanthraquinones, Cj4Hg03= Q^^^{O.^.OYi..

Ordinary Oxyanthraquinone (/3) is obtained from brom-anthraquinone and
anthraquinone-sulphonic acid, and also from phthalic anhydride with phenol
(together with erythro-oxyanthraquinone). It crystallizes in sulphur-yellow
needles, melting at 302°, and sublimes in leaflets. Isomeric erythro-oxyanthra-
quinone (a) forms yellow needles, melting at 173-180°, and sublimes at 150°.
Both oxyanthraquinones yield dioxyanthraquinone (alizarin), when fused with
caustic potash.

Dioxyanthraquinones, CnHgO, = CiiHe(0.i)(0H)2.

The ten possible isomerides (p. 894) are known. Four of them
contain the aOH-groups in one and the same benzene nucleus :
alizarin (from pyrocatechin) has the structure (2, 2), purpur-oxy-
anthin is (i, 3), quinizarin (from hydroquinone) is (i, 4); and
hystazarin is (2, 3).

Only those dioxy- and polyoxyanthraquinones possess distinct
coloring-power, in which the two free hydroxyls occupy the posi-
tion (i, 2) {Berichte, 21, 435, 1164). Consult Berichte, ig, 2327
for the spectra of the dioxyanthraquinones.

I. Alizarin, dioxyanthraquinone (i, 2), is the coloring ingre-
dient of the root of the madder {Rubia tinctoriuni), in which it is
contained as ruberythric acid (identical with morindin from Mo-
rinda ciirifolid). Through the action of a ferment in the madder
root, ruberythric acid decomposes when boiled with dilute acids or
alkalies, or by standing with water, into glucose and alizarin : —

C^^H^sOu + 2H,0 = Ci,H,0, -h 2CeHi,0e.

This decomposition into alizarin and glucose lakes place in the madder root
even when it is allowed to lie exposed to the air for some time. This was the
basis for obtaining alizarin formerly, and of the application of madder root in
dyeing. Later, different madder preparations were employed, in which the con-
version into alizarin was more complete. Thus garancin was obtained by treating
""Nmadder root with sulphuric acid, which decomposes the ruberythic acid, but does

OXYANTHRAQUINONES. " 899

not alter the alizarin produced. At present artificial alizarin is employed almost
exclusively.

Artificial alizarin was first obtained by Graebe and Liebermann,
in 1868, when they heated dibrom-anthraquinone with potassium
hydroxide. It is also produced from dichlor- and monobrom-an-
thraquinone, from the two oxy-anthraquinones and anthraquinone
sulphonic acid, by fusion with caustic-potash at 250-270°. At pres-
ent it is manufactured on a large scale by these methods. The
fusion is dissolved in water, the alizarin precipitated by hydro-
chloric acid and purified by recrystallization or sublimation. Ali-
zarin also results on heating phthalic anhydride with pyrocatechin
and sulphuric acid (p. 897).

Alizarin crystallizes from alcohol in reddish-yellow prisms or
needles, containing three molecules of water, which escape at 100°.
It melts at 282°, and sublimes in orange-red needles. It dissolves
readily in alcohol and ether, and sparingly in hot water. In con-
centrated sulphuric acid it dissolves with a dark-red color and is
precipitated by water unchanged. Its diacetate melts at 160°.

Alizarin is a diphenol, and like the substituted phenols behaves
as an acid. It dissolves with a purple-red color in the alkalies ; lime
and barium salts throw out the corresponding salts as blue precipi-
tates. Alums and tin salts produce red-colored precipitates (mad-
der lakes) ; while ferric salts form blackish-violet precipitates.

This property of alizarin yielding colored compounds with metallic oxides is
the basis of its application in dyeing and cotton printing. The goods are mor-
danted with alumina (by immersing them in aluminium-acetate, then heating,
whereby aluminium hydroxide is deposited on the fibres) and then dipped into the
solution of alizarin; the resulting alizarin-aluminate is fixed by the fibres. In
dyeing with turkey-red it is customary to mordant the cloth with oil and alum.

Alizarin-amide, Cj^HgOjjfQrr^, obtained by heating alizarin with water

to 200°, crystallizes in needles, having metallic lustre, melts at 225° and sublimes.
Heated with hydrochloric acid to 250°, or by fusion with potassium hydroxide, it
yields alizarin; when diazotized it changes to oxyanthraquin'one (p. 897).

;3-Nitro-alizarin, C6Hi/^°\c,H(N02)(OH)2 (i, 2, 3— NO2 in 3), Ali-
zarin-orange, is produced by the action of vapors of hyponitric acid (NOj) upon
alizarin, or of nitric acid upon the glacial acetic acid solution {Berichte, 12, 584).
It crystallizes from chloroform in orange-red leaflets with green reflex, and melts at
244°. It dissolves in alkalies with a violet-red color, and forms lakes.

It yields phthalic acid when oxidized with nitric acid. Isomeric a-nitro-alizarin
(l, 2, 4) is obtained by the nitration of diaceto-alizarin. It melts at 195°, and
passes readily into purpurin.

/3-Amido-alizarin results by the reduction of ^-nitroalizarin. Acetic anhy-
dride converts it into an ethenyl compound, which proves that the amido-group
occupies an ortho position relatively to a hydroxyl group {Berichte, 18, l666).

When ^-nitro-alizarin is heated with glycerol and sulphuric acid to 100° we
obtain alizarin-bluelC-^^^0 ^, a derivative of anthraquinoline (see this) [Berichte,
■ 18, 447)-

goo ORGANIC CHEMISTRY.

Of the alizarin isomerides (p. 897) quinizarin (i, 4), purpuroxanthin (1,3),
and hystazarin (2, 3) [Berichte, 21, 2501) contain both hydroxyls in one benzene
nucleus — whereas anthraflavic acid, iso-anthraflavic acid, metabenz-
dioxyanthraquinone (from ?«-oxybenzoic acid, p. 897), anthrarufin and chry-
sazin have the two hydroxyls in the two benzene nuclei.

Chrysazin is obtained from its tetranitro- compound, Cj^H2(N02)4(02)(OH)2,
the so-called chrysammic acid, by reduction and the replacement of the amid-
groups. This latter acid is obtained when aloes are digested with concentrated
nitric acid.

Trioxyanthraquinones, Ci4H502(OH)3.

These are produced on oxidizing dioxyanthraquinones or upon
fusing them with alkalies (p. 897).

I. Purpurin, CgHj<^ --,q^C8H(OH)3 (1,2,4), is present with alizarin in

the madder root, and is separated from it by a boiling alum solution, which does
not dissolve the latter. It is prepared artificially by heating alizarin and quini-
zarin with manganese dioxide and sulphuric acid to 150°; purpuroxanthin is
oxidized to purpurin by simply exposing its alkaline solution to the air. It is also
obtained from tribrom-anthraquinone. Purpurin crystallizes with one molecule
of water, in reddish-yellow needles or prisms, which, at 100°, lose water and
then sublime. It dissolves with a pure red color in hot water, alcohol, ether and
the alkalies. Lime and baryta water yield purple-red precipitates. Cloth pre-
viously acted on by mordants is dyed the same as by alizarin. It oxidizes to
phthalic and oxalic acids when boiled with nitric acid ; it yields anthracene upon
distillation with zinc dust. Its triacetate melts at 190-193°.

Purpurin-amide, CjjH502(OH}2NH2 (see alizarinamide, p. 899), is obtained
on digesting purpurin with aqueous ammonia at 150°; it crystallizes in brownish-
green needles, with metalUc lustre, and passes into purpuroxanthin by the replace-
ment of the amido-group by hydrogen.

Flavopurpurin, anthrapurpurin and oxy-chrysazin are isomerides of
purpurin. See Berichte, 21, 1 164, for their ethers.

Its tetraoxyanthraquinones, €5112(011)2. (C202)C5H2(OH)2, are the so-called
anthrachrysone, obtained by heating symmetrical dioxybenzoic acid with sul-
phuric acid (p. 898), and rufiopin, CnHgOg, obtained from opianic acid (p.
794] and proto-catechuic acid with sulphuric acid. Both yield anthracene when
heated with zinc dust.

A Pentaoxyanthraquinone, Ci^HjO, = CsH3.(OH)2(CO)2C5H(OH)3, is
formed (together with anthrachrysone and rufigallic acid) when gallic acid and
symmetrical dioxybenzoic acid are heated with sulphuric acid (Berichte, ig, 751).

Rufigallic Acid, Cj^HgOg + 2H2O, is a hexa-oxy-anthraquinone, which is
formed when gallic and digallic acids are heated with sulphuric acid. It consists
of reddish-brown crystals, losing water at 120°, and subliming in red needles. It
dissolves with an indigo-blue color in concentrated potassium hydroxide. Sodium
amalgam reduces it to alizarin.

Alkylic Anthracenes : —

(I) CeH / I )CeH^ and (2) C,H ,( | ^.C.S.,^.

y-Derivatives. • a- and p-Derivatives.

The derivatives of the first type, called /-derivatives, meso- derivatives, are pro-
duced from the alkyl hydranthranols (p. 896), on boiling with alcohol and some

MiSTHYL-ANTHRACKNE. 90I

hydrochloric acid or picric acid. They unite to characteristic compounds with
picric acid {Annalen, 212, 100).

•);■ Ethyl-anthracene, Ci4H5,(CjH5), melts at 60°, isobutyl-anthracene at
S7°, and amyl-anthracene at 59°. Chromic acid oxidizes the last to amyl-
oxyanthranol. The phenyl anthracene, Ci^Hg(CeH5), corresponding to these
alkyl derivatives, is obtained from phenyl anthranol (p. 896), on ignition with zinc
dust. It melts at 152°-

Compounds of the formula 2 can exist in two isomeric forms (a and /3). At
present but one methyl anthracene is known.

Methyl-anthracene, CuHg.CHs, is obtained on conducting the
vapors of ditolyl-methane and ditolyl-ethane through a red-hot tube
(P; S93) > ^Iso on heating emodin (see below), and chrysophanic
acid with zinc dust, as well as by prolonged boiling of benzoyl xy-
lene, C6H5.CO.C6H3(CHs)2. It occurs in crude anthracene, and is
obtained from oil of turpentine on exposure to a red heat. It re-
sembles anthracene, crystallizes from alcohol in yellow leaflets, and
melts at 190° It yields a crystalline compound with picric acid, >
and this consists of dark-red needles. Anthraquinone-carboxylic
acid is produced when methyl-anthracene, dissolved in glacial acetic
acid, is oxidized by chromic acid. Concentrated nitric acid con-
verts it into Methyl-anthraquinone, which is also present in
crude anthraquinone, and melts at 177°.

Chrysophanic Xci6.,Ci^'R^{CH^){0^){0n\ = C-^^Vi^f)^, Rheinic Acid,
is the dioxyquinone of methyl anthracene. It exists in the lichen Parmelia
parietina, in the senna leaves (of the Cassia varieties) and in the root of rhubarb
(from the Rheum variety), from which it may be extracted by means of ether or
alkalies. It crystallizes in golden yellow needles or prisms, melting at 162°, and
subliming with partial decomposition. It dissolves in alkalies with a purple-red
color. Zinc dust reduces it to methyl anthracene.

Chrysarobin, CjjHjjO,, a reduction product of chrysophanic acid, occurs in
in goa- and arroroba-powder. It is a yellow- colored powder. Air oxidizes its
alkaline solution to chrysophanic acid. The same occurs in the animal organism
{Berickte, 21, 447).

Methyl-alizarin, Cj5Hj„04, is an isomeric dioxymethylanthraquinone. It is
obtained by fusing methyl-anthraquinone sulphonic acid with alkalies. It is very
similar to alizarin, melting at 250-252°, and readily subliming in red needles.
In alkalies it dissolves with a bluish-violet color.

Emodin, CjjHj^Oj = Cj4Hj(CH3)02(OH)3, is a trioxy-quinone of methyl
anthracene. It occurs with chrysophanic acid in the bark of wild cherry and in
the root of rhubarb. If distilled with zinc dust it yields methyl-anthracene. It
consists of orange-red crystals, melting at 245-250°.

Dimethyl-anthracene, C^fl.^(C]ii^)^, has been obtained from the portions
of aniline oil boiling at high temperatures. It consists of shining leaflets, melting
at 224—225° If oxidized it yields a quinone and a mono- and dicarboxylic acid.
Isomeric dimethyl anthracenes have been obtained from xylyl chloride, CgH^
(CH3).CH2C1, on heating it with water (melting at 200°), from toluene and
CH2CI2 with AICI3 (M. P. 225°) and from ethylidene chloride, GHj.CHClj.and
benzene with AICI3. The latter contains the two methyl groups linked to the two
intermediate carbon atoms, and melts at 179°-

See Berickte, 20, 1364, upon the dimethyl anthraquinones, C^fi-fi^iCS.^^.

90 2 ORGANIC CHEMISTRY.

*
Anthracene Carboxylic Acids : —

CsH/| >C,H, C,H / I \C,H3.C0,H.

\CH ^ ^CH^

7-Acid. a- and ^-Acid.

y-Anthracene Carboxylic Acid (its chloride) is formed when anthracene is
heated with phosgene to 200° {Berichte, 20, 701). It is sparingly soluble in hot
water, readily in alcohol, crystallizes in yellowish needles, and melts at 206°, with
decomposition into carbon dioxide and anthracene. Chromic acid in acetic acid
solution oxidizes it to anthraquinone.

The a- and /3-acids are formed from the anthracene-mono-sulphonic acids by
means of the cyanides, and from the anthraquinone carboxylic acids by reduction
with ammonia and zinc dust ; the a-acid melts at 260°, the ^-acid at 280°

The anthraquinone carboxylic acids, CgH4(C202)C5H3.C02H, are pro-
duced by oxidizing th.e a- and /3-carboxyhc acids and methyl- anthraquinone with
chromic acid in acetic acid. Both melt at 285°.

Pseudo-purpurin, CjsHgO, = Q.^^fi^(OYL)^.CO,^, purpurin carboxylic
acid, occurs in crude purpurin (from madder), and crystallizes from chloroform in
red leaflets, melting at 218-220°. Further heating to 180° or boiling with caustic
potash decomposes it into carbon dioxide and purpurin.

Indene and Hydrindene Group.

Indene and Hydrindene (formerly called indonaphthene and hydrindonaphthene)
may be considered the transition members from benzene to naphthalene. They
contain besides the benzene ring, a five membered carbon ring (two C-atoms in
common with the benzene nucleus), hence may be compared with indol and
hydrindol (p. 827) with which they have many analogies (see Roser, Annalen,
247. 129)*:—

a a

y 7

Indene. Hydrindene.

The following keto-derivatives attach themselves to the preceding : —

C«H^\CH^<^H C,H,/^g)cH2, etc.

Indone. ay-Diketohydrindene.

I. Indene, CgHg, occurs together with coumarone (p. 825) in that fraction of
coal-tar boiling at 176°-! 82°. After the removal of naphthalene, it can be ex-
tracted as a picric acid compound {Berichle, 23, 3276). It is a clear oil, boiling
at 177-178° ; its sp. gr. = 1.040 at 15°. It resembles coumarone ; sulphuric acid
converts it into a resin. Bromine converts it into a dibromide, CgH^Brj, that
melts at 44.°. Sodium in absolute alcohol reduces it to hydrindene, CgHm (see
above), boiling at 176°.

7-Methyl Indene, €911,(0113), was first prepared from 7-methyl indene car-
boxylic acid (see below). It is a liquid with an odor resembling that of naph-

* C. Koenig, Theorie und Geschichte der 5-gUedrigen Kohlenstof&inge.

INDENE AND HYDRINDENE GROUP. 903

thalene. It boils at 205° (Annalen, 247, 159). It can be directly synthesized
(in slight amount) by condensing benzylacetone with sulphuric acid {Berichte, 23,
1882) :—

CeH,^^"'^>CH, = C,H /^^ACH + H,0.

CO— CH3 \ C •^— CH3

Benzyl Acetone. -y-Methyl Indene.

Some derivatives of cinnamic aldehyde deport themselves similarly. Nitro-
a-methyl cinnamic aldehyde, C|;H^(N02).CH:C(CH3).CHO, may be reduced to
amido-/3-methyl indene [Beiic/tU, 22, 1830), and nitro-a ethyl cinnamic aldehyde
to amido-/3-ethyl indene. The reaction is analogous to the formation of the couma-
rone and indol derivatives.

2. The formation of the carboxyl derivatives of indene (compare the formation
of coumarilic acid by the method of Hantzsch, p. 825), proceeds in a manner
analogous to the formation of alkyl indenes. Thus, benzylacetoacetic ester readily
changes, when digested with sulphuric acid, to y-methyl indene-^-carboxylic acid
{^Berichte, 20, 1574; Annalen, 247, 157) : —

C^H^ / ^^2\CH.C0,H_ /CH,--,

CO.CH3 ^ ^ ^CHj + "2'-'-

It melts at 200°, and decomposes further into carbon dioxide and y methyl indene
(see above).

3. The hydrindene derivatives have been obtained in the same manner as the
tetra- and pentamethylene derivatives (p. 578) : by the action of o-xylylene
bromide (p. 573) upon malonic ester and sodium alc'oholate (Baeyer and Perkin,
Berichte, 17, 125) : —

/CHaBr /CO2R /CHj /CO2R

C„H / + CH3/ = QH / >C/ + 2HBr.

^CH,Br '^CO,R ' *^CH,/ N

CO,R

The resulting ether is saponified, and we then obtain Hydrindo-naphthene
Dicarboxylic Acid, CgHg(C02H)3, melting at 199°, and decomposing into car-
bon dioxide and hydrindene carboxylic acid, CgHj.C02H, which melts at 130°,
and distils without decomposition.

The latter is also produced by the saponification of acetyl hydrindene-carhoxylic

ester, C ^ ^C r^r)} ^ C CC) R *' °'^'^i°^'^ '''°''' oxylylene bromide and aceto-
acetic ester {Berichte, 18, 378). Potassium permanganate oxidizes hydrindene
carboxylic acid to carbpphenyl glyoxylic acid (p. 765).

4. Keto-derivatives of indene and hydrindene result (l) by condensing phthalic
esters and fatty acid esters with sodium (W. Wislicenus, Berichte, 21, Ref. 642;
Annalen, 246, 347) : —

CaH./^8:g;g^J^^ + CH3.C02.C2H,=

C.H./^O^CH.CO^.C^H, + 2C,H5.0H.

The diketohydrindene-carboxylic ester thus formed melts at 75-78°, and readily
decomposes into ay-dikelohydrindene , C^H^/ pQ^CHj, colorless needles, melt-
ing at 129-131° with decomposition. It dissolves quite easily in dilute alkalies
with an intense yellow color {Berichte, 22, Ref 581 ; Annalen, 252, 72).

g04 ORGANIC CHKMISTRY.

Phthalic acid ester and propionic ester yield ^-Methyl-diketohydrindene, CgH^
(C0)2CH.CH3, melting at 85° (^«reV/5/^, 22, S8i).

(2) By the inner condensation of cinnamic acid derivatives, aided by sulphuric
acid. Thus, dibromindone is derived from /3-dibromcinnamic acid (p. 810)
(Roser, Annalen, 247, 140) : —

C,H,CBr:CBr.CO,H = CeH,/^°^CBr + H,0.

Dibromindone, CjH^BrjO, consists of orange=yellow colored needles, with
an odor resembling that of quinone. It volatilizes quite, readily with steam, and
melts at 123°.

Hydrindone could not be obtained from hydrocinnamic acid in this way;
a-methyl hydrocinnamic acid (p. 814), on the contrary, passes very readily into
^■methyl hydrindone (v. Miller, Berichte, 23, 18"""

,n/ 'VH.CH3 = C,H,/ J'^CH.CHa + H.O.
CO.OH

/"„„ ' ~ ' *^ CO /

ni- and/-Bromhydrocinnamic acids yield in this way m- axiA p-bromhydrindone,
C,H3Br/ >CH,.

/CO
Hydrindone, C„H.<' ■ J'CH,, has been prepared by saponifying d-cyan-

\ch/

benzyl-acetic ester, CgH^(CN).CH2.CH2.C02R, with hydrochloric acid [Berichte,
22, 2019) ; also by distilling calcium o-hydrocinnamic carboxylate. Hydrindone
forms colorless crystals, with an odor like that of phthalide. It melts at 40° and
boils about 244°. Its oxime melts at 146°; the hydrazone at 120°.

(3) The formation of ketoindene derivatives from naphthalene derivatives is
rather remarkable ; a six-membered benzene-ring is rearranged to a ring of five
members — similar to the production of pentamethylene derivatives from the ben-
zenes, or diphenylene glycollic acid from phenanthraquinone. This change occurs
by the action of chlorine or hypochlorous acid upon the naphthols, and naphtho-
quinones, amidonaphthols, etc. The first product consists of naphthalene keto-
derivatives with the groups — CO. CO — or CO.CCIj — ; these sustain the decom-
position (Zincke, Berichte, 20, 1265, 2890; 21, 2379, 2719). Thus dichlor-;3-
naphthoquinone and water yield first dichlorindene oxycarboxylic acid, which by
oxidation (with elimination of carbon dioxide and two hydrogen atoms) forms
dichlorindone : —

/CO.H
,C0 — CO .C(OH)/ /CO v^

CeH / I C,H / VCCI C^H / ^CCl.

^CCl = CCl ^CCI ^ ^CCl^

DichIor-)3-naphtho- Dichlorindene-oxy- Dichlorindone.

quinone. carboxylic Acid.

Dichlorindone, CgH^Cl^O, resembles dibromindone perfectly, and like the
latter is produced by the inner condensation of dichlorcinnamic acid, C5H5.CCI:
CCl.CO^H (from phenyl propiolic acid). It consists of golden yellow needles,
with an odor like that of quinone. It melts at 90° [Berichte, ao, 1265).

NATHTpALENE GROUP. 90S

4. DERIVATIVES WITH CONDENSED BENZENE NUCLEI.

The hydrocarbons belonging here contain two or more benzene
nuclei so combined that every two nuclei have two adjoining carbon
atoms in common, as seen in the following structural formulas of
the nuclei of naphthalene, CioHg, and phenanthrene, CuHm : —

C=C C=C

/ \ / \
C C— c c

\ ^ \ //

C— C C— c

\ /
c=c

Phenanlhrene Nucleus.

Phenanthrene, with three benzene rings, can also be considered
as a diphenyl, CgHj — CeHj, in which two carbon atoms, C^C, in
union with each other are inserted in the two ortho-positions of the
two benzene nuclei, in such a manner that a third benzene ring is
the result.

Pyrene, CieHm, Chrysene, CigHu, Picene, Cj^Hn, also acenaph-
thene, CiJi^a, fluoranfhene, C15H10, and other hydrocarbons have a
similar structure ; they are all found in those portions of coal-tar
which boil at high temperatures.

c c

//\ /%
c c c

c

phthal

ii 1

C C

' \^

c

ene Nucleus.

I. NAPHTHALENE GROUP.

Naphthalene, CjoHg, the parent substance of this group shows
the greatest similarity to benzene in its entire deportment. Like
benzene it is produced by the action of intense heat upon many
carbon compounds, especially if they be conducted, in form of
vapor, through tubes raised to a red heat. It is, therefore, present
in coal-tar. Numerous derivatives are obtained from it by the
replacement of its hydrogen atoms. Only the most important of
these will be mentioned.* But few direct synthetic methods are
known at present for naphthalene or its derivatives : —

(i) It is derived from phenylene butylene, CsHs.CHj.CHj.
CHiCHj, and its dibromide, on leading their vapors over heated
lime. The side-chain of four carbon atoms closes, forming a
benzene ring:— ^

CH:CH
C,H,.CH„.CH„.CHBr.CH„Br = C,H / I + 2HBr + H..

* See, further, Reverdin and Nolting, Ueber die Constitution des Naphtalins, 2
Aufl., 1887.
76

906 ORGANIC CHEMISTRY.

(2) A direct synthesis of the second benzene ring also ensues in a manner
analogous to the formation of the trimethylene and tetramethylene ring (p. 519)1
and of the hydrindene ring (p. 902) when o-xylylene bromide acts upon
disodium-acetylene-tetracarboxylic ester (p. 481) (Baeyer and Perkin, Berichle,
17, 448) :—

,CH,Br CNa(C02.R)2 /CH,— qCO^R)^

C„H / + I =CeH/ I +2NaBr.

^CHjBr CNa(C03.Rj2 ^CH^— C(C02R)2

First, we get the ester of tetrahydro-naphthalene-tetracarboxylic acid, and this
by saponification yields tetrahydro-naphthalene dicarboxylic acid. Naphthalene
results from the distillation of its silver salt. Corresponding experiments with
m- and /-xylylene bromide did not yield ring-shaped chains [Berickte, 21, 36 ;
23, 109).

It is doubtful, according to recent investigations, whether naphthalene deriv-
atives are really produced upon heating benzyl aceto-acetic ester with sulphuric
acid [Berickte, 20, IS7S; l5, 516).

(3) What is further noteworthy is the formation of a-naphthol
from phenyl-isocrotonic acid (p. 813), by its elimination of water
when boiled (Fittig, Berickte, 16, 43) : —

/CH : CH
CgHg.CHiCH.CHj.CO.OH = C^/ \ -f H^O.

^C(OH):CH
a-NaphthoI.

Phenylisocrotonic acid is readily obtained from phenyl paraconic acid (p. 793),
and the corresponding chlornaphthols are then similarly derived from the chlor-
phenyl-paraconic acids {Berickte, 21, Ref. 733; 21, 3444). a- and /3-Methyl
paraconic acids yield methyl-a-naphlhols [Berickte, 23, 96).

Acetyl-a-naphthol is prepared in an analogous manner from /S-benzal-lsevulinic
acid (p. 817).

(4) An interesting formation of a-naphthylamine is the condensation of aniline
with furfurane upon heating aniline with pyromucic acid and zinc chloride
[Berickte, 20., Ref. 221) : —

/CH:CH ,CH:CH

C,H,(NH^) -H 0/ I =CeH3(NH,)/ |

Aniline. \CH:CH ^CHrCH

Furfurane. a-Naphthylamine.

Constitution. — Naphthalene consists of two symmetrically con-
densed benzene nuclei (p. 905) (Erlenmeyer and Graebe, 1866)
and its structure may be expressed by the symbols —

I

7/^/^2 ft/\/\^^

in which the numbers indicate the eight affinities of the two ben-

NAPHTHALENE GROUP. 907

zene nuclei. According to this representation the positions i, 4, 5
and 8 are of equal value, while the same may be said of 2, 3, 6 and
7 (same as in anthracene and anthraquinone, p. 894) ; the former are
termed the ot-positions, the latter the /?. It follows, that by the
replacement of hydrogen in naphthalene two series of isomeric
mono-derivatives, C]oH,X (a and /J) can be derived, and with the
di-derivatives, CioHsX^, there are altogether ten isomerides possible.
/

These inferences relative to the number of isomerides and the accepted struc-
ture of the naphthalene nucleus are fully demonstrated by numerous reactions.
The presence of a benzene ring in naphthalene follows from its syntheses and
from its oxidation to phthalic acid, C5H4{C02H)j, in which the 2 carbon-atoms
of the carboxyl groups occupy the ortho-position. That there is a second benzene
ring is shown by the fact that in the destruction of the first ring (by oxidations)
phthalic acid or its derivatives are formed. Thus, by destroying the one ring we
obtain nitro-phthalic acid, C6H3(N02)(C02H)2, from nitro-naph(halene, CioH,
(NOj) ; if, however, we reduce nitronaphthalene to its amide and oxidize the latter,
the benzene ring containing the amido-group will be obliterated and a benzene
derivative — phthalic acid, C5H^(CO^H).2 — is again produced: —

NO, NO, ^o jj NH3

I I I 2 I yields | I | | I | 2 | yields | 2 |

\/\/ \/\co,H \/\/ CO,h/\/

Nitronaphthalene. Nitrophthalic Acid. Amido-naphthalene, Phthalic Acid.

The oxidation of the chlorinated naphthalenes led to perfectly analogous results
(Graebe, Annalen, 149, 20).

The existence of two isomeric series of naphthalene mono-derivatives, CjjHjX,
indicates the presence of the two different positions (a and /3). Atterberg pro-
duced {Berichtej g, 1736 and 10, 547) a direct proof that there are four n-positions
in naphthalene (two in each benzene nucleus).

That the a-positions correspond to I (^ 4, 5, 8) follows from the fact that the
o-derivatives alone are capable of yielding a true quinone (a-naphth'aquinone)
(Liebermann, Annalen, 163, 225). Nolting and Reverdin succeeded in showing .
that the a-positions were contiguous to the two carbon atoms held in common by
both benzene nuclei [Berichte, 13, 36). An evidence of this is the formation of
a-naphthol from phenyl isocrotonic acid (p. 906). For additional determinations
of constitution, consult Erdmann, Annalen, 227, 306.

Two adjacent positions (a and /3, or I, 2) in naphthalene have the character of
the benzene ortho-position ; their derivatives are adapted for the various anhy-
dride formations and ortho-condensations.

The positions (1,8) or (4, 5), called the peri positions, manifest a similar deport-
ment. They are especially suitable for the production of anhydrides. They differ
from the benzene ortho-position in that they incline to the formation of lactones
and sulphones {Berichte, 22, 3333), and are incapable of yielding a phenazine with
phenanthraquinone (see perinaphthylene diamine, p. 913).

Notwithstanding that naphthalene derivatives possess, in a general way, the char-
acter of benzene, they yet exhibit many differences. To express this in the formula
showing their constitution, E. Bamberger assumes that the two benzene rings in naph-
thalene are differently constructed from the usual benzene ring, and proposes a
formula similar to Baeyer's central benzene formula, with " peculiar potential
or central linkages" of the fourth C- valences (Berichte, 23, 1 124; Ref. 337 and

9o8 ORGANIC CHEMISTRY.

692; compare Claus, Jour. prk. Chemie, 42, 24,458). According to this idea,
the two middle C-atoms of naphthalene are not directly combined, but show two
potential or central valences.

Naphthalene, CioHg, occurs in coal-tar, and is obtained by
crystallization from that portion boiling from 180-200°. It is puri-
fied by distillation with steam and sublimation. It dissolves with
difficulty in cold alcohol, readily in hot alcohol and in ether. It
crystallizes and sublimes in shining leaves, melting at 79°, and
boiling at 218°. It is very easily volatilized, distils with aqueous
vapor and possesses a peculiar odor. It forms a crystalline com-
pound, CioH8.C6H2(N02)3.0H, with picric acid, which crystallizes
from alcohol in needles, melting at 149°- When boiled with dilute
nitric acid it is oxidized to pbthalic acid. Chromic acid slowly
destroys it (p. 783). Nearly all the naphthalene derivatives behave
similarly.

Derivatives of indonaphthene (p. 903) and of phthalide are among the inter-
mediate oxidation products of the various naphthalene compounds [Berichte, ig,
1156):-

QH^/ I yields C,H,/gg^^CHandCeH,(^g2>0.

„ , ,Cf^=*-H IndonaphthLe. Phthalide.

Naphthalene.

Naphthalene Hydrides. Like benzene, naphthalene forms additive products
with hydrogen. The di- and tetra-hydrides result from the action of metallic so-
dium upon its amyl-alcohol solution. Higher derivatives are produced if naphtha-
lene be heated with hydriodic acid or PH^I and phosphorus.

Naphthalene Dihydride, C^Hj,,, is an oil, boiling at 211°- It becomes a solid
on cooling, and then melts at +15°

Naphthalene Tetrahydride, CjjHjj, is derived from a?--tetrahydro-a-naph-
thylamine by the substitution of its amido-group ; its four H-atoms are, therefore,
combined in one benzene ring {Berichte, 22, 631). It is an oil with an odor re-
sembling that of naphthalene. It boils at 206°.

When naphthalene has had four hydrogen atoms added to one benzene ring, its
character is similar to that of the fatty compounds, whereas the non-hydrogenized
benzene ring manifests the character of benzene, and the abnormalities which other-
wise distinguish the naphthalene nucleus, disappear (p. 907). Tetrahydronaph-
thalene resembles butyl benzene, CgHj.CjHg, in every particular. The same de-
portment is noticed with the tetrahydrides of naphthalene derivatives, as well as
with those of the naphthylamines (p. 911) and naphthols (p. 916) (Bamberger,
Berichte, 23, II24; Ref. 337).

When chlorine is conducted over naphthalene it melts and yields chlorine addi-
tive products (p. 581). The dichloride, CgHgClj, is a yellow oil, readily decom-
posing into hydrogen chloride and chlor- na|)hlhalene, CjjHjCl. The tetrachloride.

NAPHTHALENE GROUP. 909

CijIigCl^, crystallizes from chloroform in large rhombohedra, melting at 182°.
When boiled with alkalies it breaks down into 2HCI and , dichlornaphthalene,

Halogen Derivatives.

a-Chlor-naphthalene, C,„H,C1, is produced in chlorinating boiling naph-
thalene; from naphthalene dichloride (see below) by means of alcoholic potash ;
from a-naphthalene sulphonic acid with PCI5, and from cs-amido-naphthalene by
means of nitrous acid. It is a liquid, boiling about 263°. /3-Chlor-haphthalene,
from /3naphthol and yS-naphthylamine, forms pearly leaflets, melts at 6l°, and boils
at 257°. Perchlor-naphthalene, CijClg, the final chlorination product, melts
about 203°, and boils near 400°.

a-Brom-naphthalene, CijHjBr, is produced by bromination; it is a liquid,
and boils at 280°- /3-Brom-naphthalene, from /3-naphthylamine and /3-naphthol,
consists of brilliant leaflets, melting at 68°

a-Iodo-naphthalene, Cj„H,I, produced by action of iodine upon naphthyl
mercury, solidifies only on cooling, and boils about 305°. /3-Iodo-naphthalene,
from ;8-naphthylamine, melts at 54°.

a-Fluornaphthalene, Cj„H,Fl, from a-naphthylamine, boils at 212°. /3-Fluor-
naphthalene melts at 59°, and boils at 212° {Berichte, 22, 1846).

Homologous naphthalenes result from the brom-naphthalenes by the action of
alkylogens and sodium, or more easily from naphthalene and alkyl bromides
assisted byAlClj. Methyl naphthalene occurs in slight amounts (-S^rzV/^^^, 21,
Ref 355)- The methylated naphthalenes are present in coal-tar.

a-Methyl-naphthalene,CjQH,.CH3, from a-brom-naphthalene and a-naphthyl-
acetic acid (p. 923), is liquid, and boils at 240-242°. /3-Methyl-naphthalene,
from coal-tar, melts at 32°, and boils at 242° [Bei-ichte, 17, 842).

Dimethyl-naphthalene, Cj ,,115(0113)2, from dibromnaphthalene and coal-
tar, boils at 251°.

a-Ethyl-naphthalene, Ci(|H,.C2H5, from a-brom-naphthalene, boils near 259°-
/3-Ethyl.naphthalene, from ;3-brom-naphthalene, and from naphthalene by
means of ethyl iodide and aluminium chloride, boils about 250° {Berichte, 21,
Ref. 356).

Acenaphthene, Cj^Hjq, is obtained by conducting o-ethyl naphthalene (or
benzene and ethylene) through a red-hot tube, or by the action of alcoholic potash
upon a brom-ethyl naphthalene, CjqHj.CjH^ Br (from a-ethyl naphthalene with
bromine at 180°) : —

/ \-CH
< >-CH2

this is similar to the formation of naphthalene from phenyl butylene (p. 905).
Inasmuch as acenaphthene is oxidized by a chromic acid mixture to naphthalic
acid (p. 923) the side-chain C2H4 must be arranged in the two peri-positions
(l and 8, p. 907) of naphthalene (Berichte, 20, 237 and 657). Consult Berichte,
21, 1461, upon nitro- and amido-acenaphthenes.

910

ORGANIC CHEMISTRY.

Acenaphthene occurs in coal-tar, and it separates on cooling from the fraction
boiling at 260-280°. It crystallizes from hot alcohol in long needles, melting at
95°, and boiling at 277°. Chromic acid oxidizes it to naphthalic acid, C,jHg
(COjH)^. It unites wilh picric acid to form long red needles of Cj^U^^.C^H.^
{N02)3.0H, melting at 161°. If the vapors of acenaphthene be passed over
ignited plumbic oxide, two hydrogen atoms split off and there results Acetylene

CH
Naphthalene, C,Jlg{ || , acenaphthylene, crystallizing from alcohol in yellow

\CH
plates, subliming even at the ordinary temperature, melting at 92°, and boiling
with partial decomposition at 270°. Its picric acid derivative mehs at 202°.
Chromic acid oxidizes it to naphthalic acid.

Nitroso-naphthalene, CijH,(NO), results from the action of nitrosyl bromide
upon mercury dinaphthyl in carbon disulphide solution. Ligroine throws it out
of its benzene solution in yellow warts, which redden on exposure. It melts at
89°, decomposes at 134°, possesses a pungent odor, and is readily volatilized in
aqueous vapor. It dissolves in sulphuric acid with a cherry-red color. Sulphuric
acid imparts a deep-blue color to its solution in phenol (comp. p. 591).

a-Nitro-naphthalene, CioH,(N02), is produced by dissolving
naphthalene in glacial acetic acid, adding nitric acid and digesting
for about half an hour.

It crystallizes from alcohol in yellow prisms, melts at 61°, and
boils at 304°. Chromic acid oxidizes it to a-nitrophthalic acid.

/3 Nitronaphthalene, Cj5H,(N02), is derived from /3-nitronaphthylamine
through the diazo-compound. It crystallizes in yellow needles, melting at 79°.
It yields /3-naphthylamine by reduction [BericA/e, 20, 891).

Two Dinitro-naphthalenes, Cj„Hg(N02)2, are produced when nitronaph-
thalene is boiled with nitric acid and sulphuric acid. The so-called a-compound
(1,5) consists of colorless prisms, melting at 214°; the ^-body crystallizes in
rhombic plates, and melts at 170°. The two NOj-groups occupy the two d-posi-
tions and very probably the peri- position (l, 8) (as in acenaphthene and naphthalic
acid). A third y-dinitronaphthalene (2, 4) from dinitronaphthylamine (l, 2, 4)
melts at 144° [Berichte, 20, 973). On boiling the dinitro-naphthalenes with
fuming nitric acid, three dinitro- and two tetra-nitronaphthalenes result.

Amido-naphthahnes, CuH,. NHj.,

a-Amido-naphthalene, — anaphthylamine, results from the re-
duction of a-nitronaphthalene, and is obtained on heating a-naph-
thol with ZnClj — CaClj-ammonia (p. 593). It consists of colorless
needles or prisms, readily soluble in alcohol, melting at 50°, and
boiling at 300°. It acquires a red color on exposure to the air,
sublimes readily and possesses a pungent odor. It forms crystalline

AMIDO-NAPHTHALENE. 9II

salts with acids. Oxidizing agents (chromic acid, ferric chloride,
silver nitrate) produce a blue precipitate in the solutions of the
salts : in a short time this changes into a red powder — oxynaphtha-
mine, CioHgNO. When boiled with chromic acid, naphthylamine
yields a-naphthoquinone.

The nitration of the acet-compound (melting at 159°) produces two nitro-com-
pounds ; these by saponification with caustic potash change to two nitronaphthyl-
amines, Ci|,H5(N02).NH2, a and j8 [Berichie, 19, 796). The a-compound [a,
U2 or I, 4) dissolves with difficulty in alcohol, crystallizes in orange yellow
needles, and melts at 191°. It affords a-naphthoquinone upon oxidation; the
elimination of its amido-group gives rise to ordinary a-nitronaphthalene. When
boiled with potassium hydroxide nitronaphthylamine yields a-nitronaphthol. The
/3-nitronaphthylamine [a^ or I, 2) melts at 144°, and when boiled with caustic
potash, passes into /3-nitronaphthol. Nitrous acid and alcohol convert it into
/3-nitronaphthaIene {^Berichte, 19, 802).

;5-Amido-naphthalene, ^-naphthylamine, is readily obtained by
heating /J-naphthol vi^ith ZnClj-ammonia to 200° (dinaphthylamine
is also produced). It crystallizes from hot water in leaflets, with
mother-of-pearl lustre, melts at 112° and boils at 299°. It is odor^
less. Oxidizing agents do not color it. Potassium permanganate
oxidizes it to phthalic acid.

/-Nitronaphthylamine, Ci„H5(N02)NH2, is produced by nitrating acet-/3-
naphthylamine and saponifying the product. It melts at 127°, and yields a-nitro-
naphthalene with nitrous acid and alcohol.

Various dinaphthylamines, (CioH,)2NH, are obtained upon heating the
naphthylamines with zinc chloride or with hydrochloric acid to 179-190°, or with
u- and /3-naphthols (p. 593). /3-Dinaphthylamine, a by-product in the technical •
preparation of ^-naphthylamine, forms leaflets with mother-of-pearl lustre, and
melts at 171°. When heated to 150° with concentrated hydrochloric acid it
breaks down into ^-naphthylamine and /3-naphthol. Heated with sulphur it

yields Thio-/3-dinaphthylamine, CjoHj/ g ^Ci„Hg, analogous to thio-

diphenylamine. Dinaphthyl-carbazol, ^ c'"]^ /'*^'^ (P' ^^^) ^""^ ^^^'
dinaphthylamine, 0/ p^''Tr*>NH, are formed when thio-/3-dinaphthylamine

is heated together with copper {Berichie, 19, 2241).

The phenylnaphthylamines, CioHj.NH.CjHs, result upon heating a- and
/3-naphthyl amine hydrochlorides to 240° together with aniline, or more readily by
heating a- and /3-naphthol with aniline and zinc chloride. These new compounds
combine with diazo salts, forming azo-dyes, which yield naphthophenazines, when
boiled with acids [Berichte, 20, S?^)-

Alliylic anilines are produced analogously to the alkyl anilines by heating the
naphthylamine hydrochlorides with alcohols {Berichie, 22, 1311).

Hydronaphthylamines.

Sodium acting upon the boiling amyl alcohol solution of the naphthylamines
causes the latter to add four hydrogen atoms to one of the benzene nuclei. If this
addition is made to the non-substituted benzene ring the naphthylamines will

912 ORGANIC CHEMISTRY.

continue to show in full degree their aromatic or benzene character; if the
opposite should take place, the addition being in the substituted benzene nucleus,
the naphthylamines acquire the nature of the amine bases of the paraffin series.
The first class of tetrahydro bases have therefore been designated aromatic (== ar),
while the second are called aliphatic or alicylic (= al) {Berichte, 22, 7^9). The
following tetrahydro bases are thus derived from the two naphthylamines (a- and

^■^ \/\/ ^^^ \/\/ • %/\/ ^^ ^/\/ "^

Hj H Hj Hj Hj

AT'- Tetrahydro- rtr-Tetrahydro- ^/-Tetrahydro- rt/-Tetrahydro-

a-Naphthylamine. j3-Naphthylamine. a-Naphthylamine. ^-Naphthylamine.

The aromatic hydrobases resemble the anilines. They are feeble bases, form
salts, having an acid reaction, with acids, are converted into diazo-compounds by
nitrons acid, and form azo-dyes by their union with diazo-salts (^Berichte, 22, 64).
A rather peculiar fact is that they exercise a reducing power with salts of the
noble metals. By oxidation all yield adipic acid, C4Hj(C02H)j, owing to the
destruction of the unchanged benzene nucleus.

The alicylic hydrobases manifest all the properties of the amines. They are
strong bases, react alkaline, have an odor like that of piperidine, form neutral salts,
do not change to diazo-derivatives under the influence of nitrous acid, but yield
very stable nitrites. Potassium permanganate causes the rupture of the hydrogen-
ized benzene ring, and produces o-carbon-hydrocinnamic acid.

^^'^i\(zd:CYi..(ZO^Yi. (P- 79')-

ar-Tetrahydro-a-naphthylamine, from a-naphthylamine (see above) (^Be-
richle, 21, 1786, 1892; 22, 625), is a colorless oil, boiling at 275°. ar-Tetra-
hydro-|8-naphthylamine may be obtained from /3-naphthylamine, together with
the a<r-compound. It boils at 276°.

fli'-Tetrahydro-a.naphthylamine is prepared by eliminating the NH^-group
from the non-hydrogenized benzene nucleus of tetrahydro-(l, S)-naphthylene-
diamine, CjjH|5(H4)(NH2)2. It is a colorless oil that boils at 246°. Its odor is
like that of piperidine. It absorbs carbon dioxide (see above) very energetically
(Berichte, 2£, 773, 963). ac-Tetrahydro-^-naphthylamine is produced in
larger quantities when ^-naphthylamine is acted upon with metallic sodium. It is
perfectly similar to the ac-a-compound, and boils at 249° (Berichte, 21, 847, 1112).

Perfectly analogous tetrahydrides are derived from the alkylic naph'hylamines
{Berichte, 22, 772, 1295, 1311). Cons,\i\X. Berichte, 22, 777 upon the physio-
logical action of naphthylamine hydrides.

Diamidoriaphthalenes, Cj„H|;(NH2)2, naphthylene diamines, are obtained
by the reduction of dinitro- and nitroamido-naphthalenes, also by the decomposition
of amidoazo-naphthalenes, and when dioxynaphthalenes are heated with ammonia
{Berichte, 21, Ref. 839 ; 22, Ref. 42).

(i, 2) Naphthylene Diamine (n/3), from /?-nitro-(i-naphthylamine and

AMIDO-NAPHTHALENE. 9I3

/J-naphtho-quinone dioxime (p. 921) {Berichte, ig, 179, 803), crystallizes i-n silvery
leaflets from hot water, and melts at 98°- Being an ortho-diamine it can form
azine derivatives (Berichte, 19, 180, 914).

(i, 3)-Naphthylene Diamine is derived from y-dinitronaphthalene. It is a
meta-diamine and hence forms a chrysoidine with diazobenzene sulphonic acid.

(i, 4)-Naphthylene Diamine results from the reduction of n-nitronaphthyl-
amine, and the decomposition of a-amidoazo-naphthalene, by tin and hydrochloric
acid. It crystallizes in brilliant scales, and melts at 120°. Ferric chloride con-
verts it into a-naphthoquinone, and bleaching lime changes it to the dichlor-
imide.

(1, 5)-Naphthylene Diamine is prepared from so-called a-dinitronaphthalene
(p. 910) and from (l, 5)-dioxynaphthalene. It melts at 189° and then sublimes.
Chromic acid does not oxidize it to a naphthoquinone.

(i, 8)-Naphthylene Diamine, with the amido-groups in the peri-position
(p. 907), is formed by reducing j8-dinitronaphthalene. White needles, melting at
66°. Ferric chloride forms a brown precipitate with it. It forms an aldehydine
with benzaldehyde. But it differs from the orthodiamines in that it cannot yield
a phenazine derivative with pherianthraquinone; this is because it is necessary
to have a seven-membered ring {Berichie, 22, 861) produced.
, The naphthylene diamines resemble the naphthylamines in that they are also
able to form Tetrahydro products, perfectly analogous to tetrahydronaphthyl-
amines ; these possess either an aromatic or alicylic character after the hydrogen
addition (Berichte, 22, 1374).

(i, 5)-Tetrahydronaphthylene Diamine, C,(|H5(H4)(NH2)2, from (i, 5)-
naphthylene diamine, consists of colorless crystals, melting at 77° and boiling at
264°- Its odor is like that of piperidine. It combines at the same time in a
remarkable degree (corresponding to the different position of the 2NH2-groups)
both the aromatic and alicylic character [Berichte, 22, 943, 1374). It contains
an asymmetric C-atom, therefore may be resolved into a dextro- and Icevo-rotatory
modification (Bamberger, Berichte, 23, 291). It yields a^-a-tetrahydronaphthyl-
amine by the elimination of the amido- group from the non-hydrogenized benzene-
ring. This is accomplished through the diazo -compound (see above).

Nitrous acid (or sodium nitrite) acting upon naphthylamine salts produces
naphthalene diazo-derivatives, perfectly analogous to the diazobenzene compounds
(p. 631) ; they yield azo-dyes with the anilines and phenols (p. 644).

The azonaphthalenes, C]|,Hj.Nj.Cj„Hj, could not be prepared by reducing nitro
napthalenes with alcoholic potash(p. 641).

a-Azonaphthalene results upon boiling the diazo-compound Ci|,H,.N2.Cj„H|5.
NjX, of a-amidazo-naphthalene with alcohol (p. 632) (^Berichte, 18, 298, 3252).
It crystallizes in red needles, or small steel blue prisms, melting at 190°, and sub-
liming without difficulty. It dissolves with a blue color in concentrated sulphuric
acid. This becomes violet at 180°. Boiling alcoholic sodium hydroxide and zinc
dust convert it into Hydrazonaphthalene, Cj|,H,.NH.NH.Cj„H,, which forms
colorless leaflets, melting at 275°. The latter compound, when digested with hy-
drochloric acid, changes to the isomeric Naphtidine, HjN.CioHg.CjjHj.NHj,
diamido-dinaphthyl (compare benzidine, p. 844) (Berichte, 18, 3255).

;8-Amido-azo-naphthalene (see below) under similar treatment (by means of the
diazo-compound) yields ,8 Oxyazonaphthalene, CjjHj.Nj.CjjHj.OH (Berichte,
ig, 1281). See Berichte, 20, 612 for a^-a%onaphthalene.

Amido-azonaphthalenes, C10Hj.N2-C10He.NH2.

9T4 ORGANIC CHEMISTRY.

a-Amido-azonaphthalene is formed when nitrous acid acts upon the alcoholic
solution of a-naphthlyamine; the diazo-amidonaphthalene, CjuHy.Nj.NH.Ci^H,
(p. 635),6rst formed undergoes a molecular rearrangement. To prepare it add
sodium nitrite (l molecule) to the aqueous solution of naphthylaraine hydrochloride
(2 molecules) and neutralize with soda [Berichte, i8, 298). It separates in the
form of a brown precipitate (see Berichte, 22, 590). It crystallizes from alcohol
in brownish-red needles or leaflets with green metallic lustre. It melts at 180°.
It forms rather unstable yellow-colored salts with one equivalent of the acids.
Concentrated acids color the salts dark in the presence of alcohol. Tin and hy-
drochloric acid resolve o-amidoazonaphthalene into a-naphthylamine and (l, 4)-
naphthylene diamine (p. 913). Naphthalene Red belongs to the safranine dyes
and is produced when 3-amidoazonaphthalene is heated with naphthylamine hydro-
chloride.

;3-Amido-azo-naphthaIene, from /3-naphthylamine, forms red needles and
melts at 156°. It is a very feeble base (^Berichte, ig, 1282).

a/3Amido-azo- naphthalene results from the action of a-naphthylamine upon
;8-naphthylamine diazochloride. It crystallizes in yellowish-brown needles,
melting at 152° (^Berichte, 20, 612).

When diazo salts act upon |8-naphthylamine products are obtained that manifest
the behavior of the diazo-amido, as well as that of the amidazo-derivatives. They
are probably hydrazimido compounds (p. 640) (^Berichte, 18, 3132; 20, 1167).

Naphthyl Hydrazines, Cj ,,11 j.NH.NHj, are derived from the diazo-chlorides
of the two naphthylamines by the action of stannous chloride and hydrochloric acid
(p. 6^3) (^Berichte, 19, Ref. 303). They crystallize in colorless needles, that
readily take on color by exposure to the air. The a-compound melts at 117°, the
/3-modlfication at 125°- They unite with the aldehydes and ketones forming
hydrazides; these form naphthindol compounds (p. 923) (Berichte, ig, Ref. 831 ;
22, Ref 672).

Sulpho-acids.

On digesting four parts of naphthalene with three parts sulphuric acid at 80°
we have formed a- and /3-Naphthalene-sulphonic Acids, C,oH,.S03H, which
may be separated by means of the barium or lead salts. The free acids are
crystalUne and deliquesce readily. When heated with sulphuric acid the a-acid
passes into the ;3-variety (similar to the orthophenol-sulphonic acid) ; therefore,
the latter acid is exclusively produced at higher temperatures (160°). The a-acid
decomposes upon heating with dilute hydrochloric acid to 200°, into naphthalene
and sulphuric acid, whereas the /3-acid remains unaltered.

Protracted heating of naphthalene with sulphuric acid (5 parts) to 160° produces
two Naphthalene-disulphonic Acids, Ci|,Hg(S03lI)2, a- and /3, which can be
separated by means of their calcium salts. The a acid, containing the two sulpho-
groups in two |8-positions, serves for the preparation of /3-naphthylaniine sulphonic
acid (F or <5-acid) ; this possesses technical importance {Berichte, 21, 637).

The chief product in sulphonating a-nitronaphthalene is (I, ^-nitronaphthalene
sulphonic acid, which can also be prepared by the nitration of a-naphthalene
sulphonic acid. In the latter reaction there is a simultaneous production of (l, 8)-
nitronaphthalene sulphonic acid, with the peri-position {Berichte, 20, 3162; 21,
Ref 730).

NAPHTHOL. 915

Naphthylamine Sulphonic Acids, CioH6(NH2).S03H. There are
fourteen isomerides.

(i) The action of sulphuric acid upon a-naphthylamine produces
almost exclusively {Berichie, 15, 578; 21, 2370): —

(i, 4)-Naphthylamine Sulphonic Acid, Naphthionic Acid,
which is applied in the preparation of Congo red.

It crystallizes in small needles, containing one-half molecule of water. At 14°
it dissolves in about 4000 parts of water. Its sodium salt, C]|,Hg(NH2)S03Na
+ 4H2O, crystallizes in large plates or leaflets, which lose their water usually at
temperatures above 100°.

(i, S)-Naphthylainine Sulphonic Acid, naphthalidinic acid, is formed by
the reduction of (i, 5)-nitronaphthalene sulphonic acid. Peri-Naphthylamine
Sulphonic Acid (l, 8) is obtained by the reduction of perinitronaphthalene
sulphonic acid, and is distinguished from the (i, 4)-acid in that its sodium salt is
not very soluble {Berichte, 21, Ref. 730).

The remaining four possible isomeric a-naphthylamine sulphonic acids have
also been prepared [^Berichte, 21, Ref. 23711.

(2) Four isomeric /5-naphthylamine sulphonic acids (designated a, /?, y and (S)
have been formed by sulphonaling,|3 naphthylamine (.ff^nV,4/^, 21, 637, 3483;
22, 412, 721). So-called F- or cS Naphthylamine Sulphonic Acid, with the two
side groups in the two j3-positions (2, 6 or 2, 7) has also been obtained from
a-naphthalene disulphonic acid (see above), and is especially applied in the prepa-
ration of substantive tetrazo-dyes with the benzidines (p. 845) {Berichte, 21, 637).

See Berichte, 21, 349S ; 22, 3327, for the naphthylamine disulphonic acids.

Diazonaphthalene Sulphonic Acid, Ci(|H5<f ^^ ^>0, diazonaphthionic

acid, is produced by the action of nitrous acid upon naphthionic acid suspended
in hot water or alcohol (p. 665). A yellow crystalline powder. It forms
rccellin by combining with a naphthol (p. 652).

Naphthol Black is formed by the union of azonaphthalene diazo-sulphonic

acid, Ci(,HjN2.CioH5<^(,|.^ >, with naphthol-monosulphonic acid.

Phenol Derivatives.

In the phenols of naphthalene the hydroxyls are far more reactive than in the
benzene phenols. They readily yield amido-naphthalenes with ammonia (p. 593) ;
and upon heating with alcohols and hydrochloric acid naphthol ethers result
{Berichte, 15, 1427).

(i) a-Naphthol, CioH,.OH, results from a-naphthylamine by
means of the diazo-compound, and upon fusing a-naphthalene-
sulphonic acid with alkalies. Its formation from phenyl-isocrotonic"'
acid (p. 906) is very noteworthy. It is soluble with difficulty in
hot water, readily in alcohol and ether, crystallizes in shining
needles; and has the odor of phenol. It melts at 95°, boils at
278-280°, and is readily volatilized. Ferric chloride precipitates
violet flakes of dinaphthol, CjoHuCOHj), from its aqueous solution.
The acetate, CoHv.O.C^HaO, melts at 46°; the ethyl ether, QoH,
O.QH5, boils at 270°.

gi6 ORGANIC CHEMISTRY.

Metallic sodium converts a-naphttiol in amyl alcohol solution into

«?--Tetrahydro-a-Naphthol, CioH,(HJ.OH, which can also be prepared
from ay-tetrahydro-a-naphthylamine by means of the diazo-compound i^Berichte,
21, 1892). It crystallizes in plates resembling those of naphthalene. It melts at
69° and boils at 265°. It has the character of a true phenol, inasmuch as its
hydroxyl is present in the non-hydrogenized benzene ring [Berichie, 23, 215).

When the so-called nitroso-a-naphthols (p. 920) are oxidized with potassium
ferricyanide two Nitro-a-naphthols, C,oHs(N02).OH, a and /3, result; these
are also obtained when the two nitro-a-naphthylamines are boiled with caustic
potash (p. 667). The a-nitro-body (l, 4) melts at 164°; its sodium salt was
applied as Campo Bella Yellow. Its reduction gives rise to Amido-a-naphthol,
C,„H5(NH2).OH (l, 4), which is oxidized to a-naphthoquinone by ferric
chloride.

/3-Nitro-a-naphthol (i, 2) is very volatile with steam, and melts at 128°
{Berichte, 15, 1815).

Dinitro-a-naphthol, C,jH5(N02)20H, is produced by the action of nitric
acid upon a-naphthol, a-naphthol sulphonic acid, upon both nitro-a-naphthols,
and upon a-naphthylamine. It is obtained from the a-naphthol sulphonic acid
by digestion with common nitric acid. It is almost insoluble in water, sparingly
soluble in alcohol and in ether, crystallizes in fine, yellow needles, and melts at
138°. It decomposes alkaline carbonates, and forms yellow salts with one equiva-
lent of base. The salts dye sillc a beautiful golden-yellow. The sodium salt,
C],H5(N02)2.0Na + HjO, finds use in dyeing, under the name of naphthalene
yellow (Mzirtius yellow). The potassium salt of dinitronaphthol-sulphonic acid,

CidH4(N02)2 \ r^l > obtained by the nitration of naphthol-trisulphonic acid, is

naphthol yellow.

Further nitration of dinitronaphthol with nitric-sulphuric acid produces Tri-
nitronaphthol, Ci(,H4( NO 2)3.011, which crystallizes from glacial acetic acid in
yellow needles or leaflets, melting at 177°. lis salts show the same color as
naphthalene yellow. '"

(I, 4)-Amido-a-naphthol, C,oHj(NHj).OH, results from the reduction of
(i, 4)-nitronaphthol, and by the decomposition of a-naphthol orange, Cj|,Hg(OH).
N2.CgHj.SOgH (from a-naphthol and diazo-benzene sulphonic acid). It is very
unstable even in the form of a salt. It yields a-napthoquinone by oxidation.

(l, 2)-Ainido-a-naphthol, from (l, 2)-nitronaphthol, oxidizes in the air to a-

/°

naphthoquinonimide,C,„H„(NH)0, orC, qHj^' | , forming violet leaflets (.5^-

^NH
richte, 18, 57^). Chromic acid oxidizes it to ;3-naphthoquinone. (i, 5)-Amido-
a-naphthol is formed when naphthylamine sulphonic acid (p. 9I4) is heated with
alltalies. It combines with naphthalene diazosulphonic acid to form a dye with a
blue color {Berichte, 23, Ref 41).

a-Naphthol Sulphonic Acids,CjoHg(OH).S03H.

Two acids (a- and ;3-) are produced when a-naphthol is digested with concen-
trated sulphuric acid (2 parts.) The a-oa'i/ (Schaeffer) has the position (l, 2) ;
ferric chloride imparts a deep blue color to it. The p-acid is (l, 4) and is derived
from naphthionic acid (p. 915) {Berichte, 22, 996 ; 21, Ref. 731). (l, 5)-Naph-
thol Sulphonic Acid may be obtained from naphthylamine sulphonic acid. Peri-
naphthol Sulphonic Acid (i, 8) is formed from peri-naphthylamine Sulphonic
acid by decomposing its diazo-derivative with water. It then separates as a lac-
tone-like anhydride, C,„H./„„ >, naphsulphtone. This consists of shining

\OU2

prisms, melting at 154°. It dissolves with difficulty in water and alcohol. It shows
neutral reaction. It dissolves in the hot alkalies, forming salts of perinaphthol sul-

NAPHTHOL. 917

phonic acid ; when the latter is liberated it dissolves quite easily in water, and is
colored dark green and then red by ferric chloride {Berichle, 21, Ref. 731). See
Berichte, 23, 3088, upon the a-naphthol-disulphonic acids.

2. /J-Naphthol, CioH,.OH, from ^-naphthalene-sulphonic acid
and /S-naphthylamine, is readily soluble in hot water, crystallizes in
leaflets, melting at 122°, and boiling at 286°, and is very volatile.
Ferric chloride imparts a greenish color to the solution and sepa-
rates dinaphthol, C2oHi2(OH)2, melting at 216°. The acetate melts
at 61°.

Metallic sodium acting upon the amyl alcohol solution of ;8-naphthol produces
both aromatic and alicylic tetrahydronaphthols (just as j3-naphthylamine yields
the two tetrahydrides, p. 912) {Berichte, 23, 197, 1 127).

ar-Tetrahydro-/3-naphthol, Ci^HjiOH, forms silvery white needles, melting
at 58° and boiling at 275°. Its odor is like that of phenol, and in its entire de-
portment it resembles the benzene phenols {Berichte, 23, 885, 1129).

a<:-Tetrahydro-|8-naphthol is a viscid oil, with an odor like that of sage. It
boils at 264°- It differs from the phenols in being insoluble in alkalies, its i?bar-
acter corresponds to that of the paraffin alcohols, and it closely resembles borneol
and menthol, which possess a similar constitution {Berichte, 23, 204).- ,

By the oxidation of so called a-nitroso-^-naphthol (p. 920), we obtain o-Nitro-
/3-naphthol, Ci|,Hb(N02).0H, which is also formed from nitrQ-/3-naphthyl-
amine, when it is boiled with sodium hydroxide. It consists of ;brown leaflets,
melting at 103°. Dinitro-^-naphthol, CioH5(NOj)2.0H, is obtained' by; the ni-
tration of ^-naphthol in alcoholic solution, and also from j3-naphth^lamirie {Be-
richle, 17, H71). It melts at 195° {Berichte, 23, 2542).

Amido-/3-naphthol, C,„H5(NH2).OH (i, 2), is obtained in the reduction of
nitro-/3-naphthol (1,2) with tin and hydrochloric acid ; also from /?-naphthol orange
(see below) or from benzene azo-/3-naphthol by decomposition with tin and hydro-
chloric acid {Berichte, 16, 2861). Its hydrochloride crystallizes in white needles ;
it yields /3-naphthoquinone when oxidized.

On the addition of alcoholic /3-naphthol to the solution of diazo-benzehe-sul-
phonicacid we.get;3-Naphthol-azo-benzene-sulphonic Acid, CidH5(OH).N2.
CjHj.SOjH, whose sodium salt is the ^-Naphthol-orange — Mandarin. The diazo-
group occupies the ortho-place referred to hydroxyl (p. 644) ; tin and hydrochloric
acid decompose the azosulphonic acid into amido-^-naphthol (l, 2) and sulphanilic
acid. By the conjugation" of diazo-naphthalene sulphonic acid (p. 915) and^-
naphthol (above), ^-Naphthol-azo-naphthalene-sulphonic Acid, CijHg
(OH).N2.Ci„Hj.S03H, is produced. Its sodium salt, the so-called Pure red or
Rocellin, is used as a substitute for archil and cochineal. The Bieberich scarlets
are formed by the conjugation of /3-naplithol with diazo-azobenzene-sulphonic acids.

/3-NaphthoI Sulphonic Acids, CioHe(OH).SOgH.

Four of the seven possible isomerides are known. They are applied in the prepa-
ration of colors {Berichte, 21, 3473).

When jS-naphthol is dissolved in concentrated sulphuric acid at the ordinary
temperature the first product is ^ naphthyl sulphonic acid, CjoHj.O.SOjH. By
continuous digestion this is almost entirely changed to /3-naphthol-^-sulphonic
acid (Schaffer's sulpho-acid) (probably 2, 6) {Berichte, 18, Ref. 89). /3-Naph-

9l8 ORGANIC CHEMISTRY.

thol-a-sulphonic acid (Baeyer's Acid or Crocein Acid) (2, 5) or (2, 8) (formerly
thought to be 2, l) is produced at the same time [Berichie, 21, 3489; 22, 396,
453). It serves for the preparation of crocein scarlet.

The (2, 7)-;3 Naphthol Sulphonic Acid (Cassella's Acid, or F-acid) is pro-
duced when a-naphthalene disulphonic acid is fused with caustic soda at 200-250°.
The (2, 5)-Naphthol Sulphonic Acid (of Dahl) is made by diazotizing /3-naph-
thylamine-y-sulphonic acid. Four Amido-Naphthol-Sulphonic Acids, CuHj
(NHj)(0H).S03H, have been obtained from the azo dyes, formed by the reduction
of the products resulting from the union of these four /3-naphthol acids with diazo-
derivatives. Two /3-naphthol disulphonic acids, Cj|,H5(OH)(S03H)j, called R-
and G-acid, are produced when /3-naphthol is digested with sulphuric acid (4 parts)
at 100°. They form various Ponceaus by conjugation with xylidines and cumi-
dines. The G-acid, obtained in perfectly pure condition from /3-naphthol-(r-suI-
phonic acid (see above), is known in commerce as /3-Naphthol-7-Disulphonic
Acid ; it yields especially valuable dyestuffs [Berich/e, 21, 3478). See Berichie,
22, 822; 23, 3045, for Thionaphthols.

Dioxynaphlhalenes,Q■^^Yi ^{OYi)„. Six of the ten possible isomerides are known ;
of these we mention those corresponding to the two naphthoquinones.

a-Hydronaphthoquinone (l, 4) is obtained from a-naphthoquinone on boiling
with hydriodic acid and phosphorus. It crystallizes from hot water in long needles,
and melts at 173°. Chromic acid readily oxidizes it to a-naphthoquinone.

/3-Hydronaphthoquinone (1,2) separates in silvery leaflets, melting at 60°,
when a solution of /3-naphthoquinone in aqueous sulphurous acid stands for some
time. It dissolves in the alkalies with a yellow color which becomes an intense
green upon exposure.

(1, 5)-Dioxynaphthalene is derived from a-nitronaphthalene sulphonic acid
and by fusing /-naphthalene disulphonic acid with caustic potash. It readily
sublimes in thin leaflets and melts at 1 86°. Chromic acid oxidizes it to juglone
(p. 919). (2, 7)-Dioxynaphthalene is obtained from a-naphthalene disulphonic
acid, crystallizes in long needles and melts at 190° {^Berichie, 23, 519).

Trioxynaphthalenes, Cj|,IT5(OH)3.

Two trioxynaphthalenes, a- and /3-Hydrojuglones, occur in green walnut shells
{Berichie, 18, 463, 2567). a-Hydrojuglone (i, 5) crystallizes in needles or
leaflets, mehing at 169°. In the air it rapidly oxidizes to juglone (see below).
If it be distilled it changes to /3-Hydrojuglone, which dissolves in water with
more difficulty and does not yield juglone upon oxidation. It reverts again to
a-hydrojuglone when boiled with dilute alcoholic hydrochloric acid. The two
hydrojuglones yield the same triacetyl compound with acetic anhydride.

Quinones.

In addition to ordinary a-naphthoquinone, corresponding in all respects to benzo-
quinone, there is a /^-naphthoquinone, which represents an ortho-diketone (com-
pare o-benzoquingne, p. 704).

(i) a-Naphthoquinone, CioHgOa (i, 4), is formed in the oxi-
dation of a-naphthylamine, nitro-a-naphthol, diamidonaphthalene

NAPHTHOQUINONE. 919

(i, 4), and amido-a-naphthol (i, 4) with chromic acid; further,
on heating naphthalene in glacial acetic acid with chromic acid
(p. 699, Berichie, 20, 2283). It crystallizes from hot alcohol in
yellow rhombic plates, melting at 125° and subliming under 100°.
It possesses the usual quinone odor, is very volatile, and distils
over in a current of steam. Nitric acid oxidizes it to phthalic acid,
and by reduction forms a-naphthohydroquinone (see above).

ar-Tetrahydro-n-naphthoquinone, Q-^^^ifi^O^, is produced by the oxid-
ation of ar-tetrahydro-a-naphthylamine (p. 912) with chromic acid. Its pro-
nounced benzene character harmonizes with its constitution. It resembles benzo-
quinone more closely than a-naphthoquinone. It melts at 55°, but is incapable
of forming a hydrazone (j5f?-2V/4/^, 23, 1131). a-Naphthoquinone and phenyl-
hydrazine combine to hydrazones (distinction from ordinary benzoquinone). The
dioxinie is derived from the monoxime by means of hydroxylamine. The Anilide,
CjdH5(NH. €5115)02 (p. 700), results from the union of a-naphthoquinone with
aniline. It crystallizes in red needles, that melt at 191°. Boiling dilute sodium
hydroxide decomposes it into aniline and./J-oxy-a-naphthoquinone, C^j^^iO^.
OH (l, 4, 2), naphthalene acid, that melts at 188°.

Juglone is an a-oxy-a-naphthoquinone, Ci„H5(02).OH (l, 4 — 5 or 8). The
best method to obtain it consists in oxidizing re-hydrojuglone with ferric chloride.
It may be synthetically prepared by oxidizing (l, 5)-dioxynaphthalene with
chromic acid {Berichte, 20, 934). It is almost insoluble in water, consists of
yellow needles and melts with decomposition about 150-155°. It dissolves in
alkalies with a violet color. Zinc dust converts it into naphthalene. Nitric acid
converts it into dinitro-oxyphthalic acid (juglonic acid) (Berichte, ig, 164).

The following are dioxy-a-naphthoquinones, C]jH^(0H)20 : —

Oxy-juglone, formed by the oxidation of the alkaline solution of juglone on
exposure to the air. Golden yellow plates, that melt at 220°, with decomposition.
Naphthalizarin, corresponding to the alizarin of anthracene, is derived from
o-dinitronaphtbalene by heating it with concentrated sulphuric acid and zinc. It
sublimes in red needles with green metallic reflex, dissolves in ammonia with a
bright blue color, and yields violet-colored precipitates with lime or baryta water.

/°
a-Naphthoquinone Chlorimide, C,|,H,(' I , obtained from amido-a-

^NCl

naphthol hydrochloride with a solution of bleaching lime (p. 705), consists of

brown needles, melting at 85°. It yields a-Naphthol-blue (p. 707), ivith dimethyl

aniline.

(2) ^-Naphthoquinone, CioHgOa (i, 2), is produced on oxid-
izing amido-/3-naphthol with chromic acid or with ferric chloride
{Berichte, 17, Ref. 531). It also results from the decomposition
of /S- naphthol orange (p. 917) and further oxidation with ferric
chloride {Berichte, 21, 3472). It crystallizes from ether or ben-
zene in orange-colored leaflets, and decomposes at 115-120°. It
is distinguished from the real quinones (p. 698), by being odorless
and non-volatile. It closely resembles anthraquinone, and es-
pecially phenanthraquinone (p. 925); like the latter it must be
considered an ortho-diketone : —

.CO.CO .

\CH:CH/

920 ORGANIC CHEMISTRY.

In accordance with this view it combines with one and two mole-
cules of HjN.OH, yielding quinoximes.

Phenylhydrazine unites with it forming the hydrassone, Ci|,H50(N2H.CjHj)
(p; 921), melting at 138°. Sulphurous acid reduces it at ordinary temperatures to
j8-naphtho-hydroquinone. Potassium permanganate oxidizes it to phthalic acid.

Naphthoquinoximes or Nitrosonaphthols. These are produced when the
alcoholic solutions of the naphthoquinones are boiled with hydroxylamine hydro-
chloride, and by the action of nitrous acid upon the naphthols. Their constitution
corresponds to the formulas : —

,N0 ^O

\0H ^N.OH,

Nitrosonaphthol. Quinoxime.

which are probably tautomeric (pp. 674, 699). Three isomerides are produced
according to the preceding methods : —

,C(N.OH).CH ,CH:CH /CH:CH

CeH/ ^ CeH / | C^H / —_

\ CO.CH \C0.C:N.0H \C(N.OH).CO

a-Nitroso-a-naphthol. j8-Nitroso-a-naphthol. a-Nitroso-p-naphthol.

a-Naphthoquinoxime. j3-Naphthoquinoxime.

Nitrous acid acting upon a-naphthol produces both a- and ;3-nitroso-a-naphthoI
(Preparation, Berkhie, 18, 706). The first may be obtained from a-naphtho-
quinone by means of hydroxylamine [Berichte, 17, 2064). Nitrous acid converts
/3-naphthol into but one compound a-nitroso-^-naphthol (Preparation, Berichte,
18, 705), whereas ;3-nitroso-a-naphthol is the product if hydroxylamine be used
[^Berichte, 17, 215). The three compounds behave like feeble acids ; they dissolve
in alkaline carbonates, and are again liberated by carbon dioxide. They form
corresponding nitronaphthols upon oxidation.

a-Nitroso-a-naphthol ar a-naphthoquinoxime consists of colorless needles, melt-
ing at 190°. ji-Nitroso-a-naphthol (/3-naphthoquinoxime) crystallizes in needles
from hot water, and melts at 152°. a-Nitroso-^-Naphthol forms stout yellow-
brown prisms, melts at 160°, and volatilizes with aqueous vapor [Berichte, 17,
2584). It precipitates various metals from solutions of their salts, and may be
employed in separating cobalt from nickel [Berichte, 18, 699), iron from alumi-
nium (Berichte, 18, 2728), and for the determination of copper and iron [Berichte,
20, 283).

The methyl ethers of /3-nitroso-a-naphthol and of a-nitroso-/3-naphthol, Ci(,Hg
(N.O.CHj)O (derived from the silver salts with methyl iodide), are reduced to
amidonaphthols by tin chloride [Berichte, 18, 571). The behavior of the two
compounds toward hydroxylamine hydrochloride argues in favor of their being
quinoximes [Berichte, ig, 341). The same conclusion is deduced from the be-
havior of a- and ^ naphthoquinones toward methyl hydroxylamine HjN.O.CHj
[Berichte, 18, 2225).

a- Naphthoquinone Dioxime, CioHg^„'„tr) 's formed upon boiling re ni-

troso-re-naphthol with hydroxylamine hydrochloride and aqueous alcohol. It crys-
tallizes in colorless needles and melts at 207°. Acetic anhydride converts it into
a diacetate [Berichte, 21, 433).

CYAN-NAPHTHALENE. 92 1

^-Naphthoquinone Dioxime, *-io^6\ n DH (I'i-isonitroso-naphthalene

hydrid e) , is derived from /3-nitroso-a-naphthol, and from a-nitroso-/3-naphthol by the
action of hydroxylamine hydrochloride {Berichte, 17, 2064, 2582). It crystal-
lizes from water in yellow needles and melts at 149°. It forms the anhydride,

CjijHg < jj^O, melting at 78°, when digested with alkalies. Stannous chloride

reduces the dioxime to (i, 2)-naphthylenediamine. /3-Naphthoquinone dioxime
colors iron and cobalt mordants brown. The same may be said of other ortho-
dioxime and ortho-oxy-oxime (1,2) dye-substances, but not of the para-dioximes
(Berichte, 22, 1349).

Quinone Phenylhydrazones.

Phenylhydrazine hydrochloride acting upon a-naphthoquinone in glacial acetic
acid produces a-naphthoquinone phenylkydrazone, identical with Benzene-azo-
naphthol AtxlytA from a-naphthol and diazobenzene chloride. The two formulas,

„ „^0 (I) , , P w/OH

"-io"6\N.NH.CeH5 (4 ^^°- "-""6\N;N.C3H5

are probably, therefore, tautomeric, and the compound reacts at the same time as
a phenol and a base (^Berichte, 17, 3026). However, ^-naphtho-quinone phenyl-
kydrazone differs from benzene-azo /3 naphthol, CjdHg-l >t jj r jj (Berichte, 18,
796; 21, 414). The toluenes exhibit a similar deportment {Berichte, 19, 2486).

Alcohols, Ketones, Nitriles.

a-Naphthobenzyl Alcohol, CjdHj.CHj OH, from a-naphthobenzylamine
(from a-naphthonitrile, see below), crystallizes in long, brilliant needles, melts at
60° and boils at 301° [Berichte, 21, 257). Chromic acid oxidizes it to

a-Naphthaldehyde, CmHj.CHO, a thick oil, boiUng at 291° (Berichte 22,
2148).

/3-Naphthaldehyde, CiqHj.CHO, is produced by the distillation of the calcium
salts of |3- naphthoic and formic acids, and by the oxidation of /3-naphthyl carbinol,
CjoHi.CHj.OH (from ;8-cyan naphthalene). It crystallizes from hot water in
shining leaflets, that melt at 59° (Berichte, 16, 636; 20, 1 1 15).

Dinaphthyl Ketones, CjoH,.CO.CioHj, a- and ./3-, result by the condensation
of a- and ^-naphthoic acids with naphthalene upon heating them with phosphorus,
pentoxide, also by the action of naphthalene and zinc upon a- and ^-naphthoyl
chloride, C,„H,.C0C1 (p. 855).

a-Naphthyl-methyl Ketone, CioHj.CO.CHj, is derived from naphthalene
and acetyl chloride by means of aluminium chloride. It melts at 34° and boils
about 295°. It unites with hydroxylamine and phenylhydrazine. Potassium per-
manganate oxidizes it to naphthyl glyoxylic acid (p. 923).

The corresponding cyanides or nitriles may be obtained by the distillation of the
alkali salts of the naphthalene-disulphonic acids, or the phosphoric esters of the
naphthols with potassium cyanide (Berichte, 21, Ref. 834).

a-Cyan-naphthalene, C]„H,.CN, has also been prepared from naphthyl forma-
mide, CupH^.NH.COH (from naphthylamine oxalate) (comp. p. 633) as well as
from a-naphthalene diazochloride by means of copper and potassium cyanides
{Berichte, 20, 241). It dissolves readily in alcohol, and forms flat needles, melt-

77

92 2 ORGANIC CHEMISTRY.

ing at 37.5°, and distilling at 298°. /3-Cyan-naphthalene, from ;3naphthalene
sulphonic acid, crystallizes in yellow prisms, melts at 61°, and distils at 304°.

Similarly, two naphthalene-dicyanides, Ci|,Hg(CN)j, are produced from the
two naphthalene disulphonic acids. Both sublime in shining needles ; the a-com-
pound melts at 268° and is almost insoluble in the ordinary solvents; the ;3-di-
cyanide dissolves in hot alcohol, and melts at 297°.

Naphthalene carboxylic acids are produced on saponifying the cyan-naphtha-
lenes with alcoholic potassium hydroxide.

Naphthalene Carboxylic Acids.

a-Naphthoic Acid, CioHj.COjH, from a-cyan-naphthalene, by
saponification with alcoholic soda at 160° {Berichte, 20, 242; 21,
Ref. 834), is also prepared by fusing potassium a-naphthalene sul-
phonate with sodium formate, and by the action of sodium amalgam
on a mixture of a-brom-naphthalene and chlor-carbonic ester. It
consists of fine needles, melting at 160°, and dissolving in hot
water with difficulty, but readily in hot alcohol.

The nitration of a-naphthoic acid produces two nitro-naphthoic acids, CjjHj
(N02).C02H. a- Nitronaphthoic Acid(l, 5) is almost totally insoluble in hot water.
It forms delicate needles and melts at 239°. Potassium permanganate oxidizes it
to a-nitrophthalic acid ; boiling nitric acid converts it into a-dinitro-naphthalene.
Ferrous sulphate and ammonia reduce it to a stable amido-naphthoic acid (l, 5),
melting at 212° [Berick/e, ig, 1981).

/3-Nitronaphthoic Acid (1,8) contains the two side groups in the peri-posi-
tion. It consists of hard prisms and melts at 275°. Boiling nitric acid converts
it into (l, 8)-dinitronaphthalene. Ferrous sulphate and ammonia reduce it to
(i, iyamidonaphthoic acid, which when free passes quite readily into its inner

anhydride, Naphthostyril.CjjHg/^TT^. The latter forms yellowish-brown

needles, melting at 179° {Berichte, 19, 1 131). Naphthalic acid is produced by
the rearrangement of the amido-acid through the diazo-compound into cyan-
naphthoic acid etc. [Berichte, 20, 240).

/S-Naphthoic Acid, CioH,.C02H, from /?-c3'an-naphthalene,
crystallizes from hot water in long, silky needles, and melts at 182°.
Baryta converts it (as well as a-naphthoic acid) into naphthalene
and carbon dioxide.

Oxy-naphthoic Acids, C,(,Hg(OH).C02H. Naphthol carboxylic acids.
Eight of the fourteen possible isomerides are known.

a-Naphthol Carboxylic Acid (1,2) corresponds to salicylic acid. It is pro-
duced in an analogous manner from a-naphthol, best by heating the sodium salt
with CO2 under pressure (p. 768). It dissolves with difficulty in hot water, crys-
tallizes in needles and melts at 186°. Ferric chloride imparts an intense blue
color to it {Berichte, 21, 1 186).

/3-Naphthol Carboxylic Acid (2, i — OH in 2) is derived from ^S-naphthol-
sodium with carbon dioxide and pressure at 120-145° [Berichte, 20, 2701), as
well as by carefully fusing /3-naphthol aldehyde, Ci„H5(OH).CHO, with caustic

NAPHTHO-FURFURANE. 923

potash {Bei-ickte, 15, 805). It crystallizes from dilute alcohol in needles, is
colored violet by ferric chloride, melts at 156° when rapidly heated and decom-
poses into CO2 and naphthol. It sustains an analogous decomposition when it is
boiled with water.

If /3-naphthol-sodium be heated more strongly, 200-250° — in a current of
carbon dioxide the product will be an isomeric naphthol carboxylic acid. This is
colored yellow and melts at 2l5° {Berichle, 23, Ref. 612).

(i, 8)-Naphthol Carboxylic Acid is derived from (i, 8)-amido-naphthoic acid
(see above) by means of the diazo-compound. It melts at 109° and breaks down

into water and its y-lactone, Cx,^i(rr)/> melting at 169°-

a-Naphthyl-glyoxylic'Acid, Naphthoyl Formic Acid, CijHj.CO.COjH,
obtained from a-naphthoyl chloride by means of the cyanide (p. 762), and from
a-naphthyl methyl ketone by oxidation with permanganate, melts at 1 1 3°, and
yields a-naphthyl acetic acid, CiuHj.CHj.COjH, when reduced; this melts at
131°.

Naphthalene Dicarboxylic Acids, CioHs(C02H)2. Six of the ten possible
isomerides are known. When acenaphthene and ace-naphthylene are oxidized with
chromic acid we get Naphthalic Acid (i, 8), which contains the carboxyl groups
in the peri-position. It crystallizes in small needles, which decompose at 140-
HO°, without melting, into water, and its anhydride, Cj(|Hg{C0)20, that crys-
tallizes from alcohol in needles, and melts at 266°. It is perfectly analogous to
phthalic anhydride {Berichle, 20, 240).

Tetrahydro-naphthalene Dicarboxylic Acid, Ci(|Hj„;^„„'iTT (/3,/3), ob-
tained by saponifying the ethyl ester of the tetracarboxylic acid (p. 966), melts at
199° and decomposes into water and its anhydride, that melts at 184°.

Naphthalene Tetracarboxylic Acid, C,„H^(C02H)^ (l, 8-4, 5), with the
carboxyl groups in the two peri-positions of naphthalene, results when pyrenic acid
is carefully oxidized by potassium permanganate {^Berichle, 20, 365). It forms
shining needles and yields naphthalene upon distillation with lime.

Derivatives of Naphtho-furfurane and Naphthindol (p. 825).

Naphtho-furfurane. Naphthopyrrol.

The naphthofurfurane derivatives (a and P) are derived, analogously to the ben-
zofurfurane compounds, by the action of sodium a- and /3-naphthol upon chlor-
acetoacetic ester (p. 817). One derivative is formed from each, whereas according
to the naphthalene formula two (l, 2) and (l, 8), and (2, l) and (2, 3) isomerides
are possible with each. The first products are methyl-naphtho-furfurane carboxy-
lic esters, Cj|,Hj:C20(CH3).C02R; by saponification these yield the free acids,
from which by loss of carbon dioxide are obtained the methyl naphtho-furfur-
anes, q„Hg:C2H0(CHs) {Berichle, 19, 1301).

The naphthindol or naphthopyrrol derivatives, like the indol derivatives, are
prepared from the compounds of a- and /3-naphthylhydrazines with aldehydes,
ketones and ketonic acids, when they are heated together with zinc chloride {Be^
richle, ig, Ref. 831 ; 20, Ref. 428). a-Naphthifldol, CipHgrCgHjN, crystal-
lizes in leaflets and melts at 175°. j8-Naphthindol is a liquid and boils above
360°.

924 ORGANIC CHEMISTRY.

See Berichte, 21, 114, for /3-Naphthoxindol and j9-NaphthisaUn.
Thionaphthene and Thiophtene bear the same relation to naphthalene that
thiophene bears to benzene : —

C^h/ )cH and HC^ Y ^^•

Thionaphthene.

\s/\s/

Thiophtene.

Thionaphthene, CjHgS, has already been given as benzothiophene (p. 826).

Thiophtene, CgH^Sj, consisting of two condensed thiophene nuclei, is pro-
duced when citric acid is heated with P^Sj (p. 529). It is an oil, boiling at 225°.
[Berichte, 19, 2444).

2. PHENANTHRENE GROUP.

Phenanthrene, CuHm (p. 905), occurs in coal-tar and in the
so-called " stubb," a mass of substance obtained (together with fluor-
anthene) in the distillation of mercury ores in Idria. It is prepared
synthetically (with diphenyl, anthracene and other hydrocarbons)
from various benzene compounds, by conducting their vapors
through a red-hot tube, e. g., from toluene, stilbene, diphenyl and
ethylene, from dibenzyl and ortho-ditolyl : —

CgHs.CHj
CgH-.CH^

and

CgH^.CHj
C,H,.CH3

yield

CjH-.CH

1 1 + 2H,.
CeH,.CH

Dibenzyl.

o-DitoIyl.

Phenanthrene.

Sodium acting on ortho-brom benzylbromide, QHjBr.CHj.Br,
also produces it (together with anthracene, p. 893). It also appears
in the condensation of coumarone with benzene iipon the applica-
tion of heat {Berichte, 23, 85).

Phenanthrene is obtained from crude anthracene by talking that fraction boiling
at 3€0-350°, concentrating it by further distillation, and crystallizing from alcohol,
when anthracene will separate-first. The phenanthrene is obtained from its picric
acid compound, or by oxidation with chromic acid, when the anthracene will be
first attacked {Annalen, ig6, 34; Berichte, 19, 761).

Phenanthrene crystallizes in colorless, shining leaflets or plates,
melting at 99°, boiling at 340°, and subliming readily. It dissolves
in 50 parts of alcohol at 14°, and in 10 parts (95 per cent.) on boil-
ing, and readily in ether and benzene. The solutions exhibit a blue
fluorescence. The picric acid compound, Ci4Hio.C6H2(N02)3.0H,
separates in yellow needles on mixing the alcoholic solutions,. and

PHENANTHRAQUINONE. 925

melts at 144°. Phenanthrene is oxidized by boiling with chromic
acid to phenanthraquinone, then to diphenic acid.

Phenanthrene must, from its formation from dibenzyl and ortho-brombenzyl
bromide, be considered a diphenyl derivative, in which two ortho- places of the
two benzene nuclei are united by the group C^Hj ; the latter, therefore, forms,
with the four carbon atoms of the two benzene rings, a third normal benzene ring.
So-called phenanthraquinone, the oxidation product of phenanthrene, must be
regarded as an ortho-diketone (p. 699), because further oxidation converts it into
diphenic acid (p. 849), in which the two carboxyl groups are inserted in two ortho-
places of diphenyl : —

CsH^.CH C,H..CO CgH-.CO.H

I II I ' I I

CeH^.CH CeH^.CO CjH^.CO^H

Phenanthrene. Phenanthraquinone. Diphenic Acid.

Hydrogen additive products result upon heating phenanthrene with hydriodic acid
and phosphorus. The tetra-hydride, Cj^Hjj, boils at 310°, and solidities on cool-
ing. The Per-hydride, Cj^H,^, melts at -3° and boils at 270-275° (Berichte, 22,
779). Chlorine produces substitution products, of which the octo-chloride, Cj^HjClg,
melts at 270-280°, and by further chlorination (comp. p. 580) is split into hexa-
chlorbenzene, CgClg, and CCl^. Bromine combines with phenanthrene in CSj
solution, yielding the dibromide, Cj^Hjj.Brj, which melts at 98°, with decom-
position, and readily breaks up into hydrogen bromide and bromphenanthrene,
CjjHgBr. This melts at 63°, and is oxidized to phenanthraquinone by chromic
acid."

Ordinary nitric acid converts phenaiithrene into three niirophenantkrenes,
Cj4Hg(N02), which yield three arnido-fhenanthrenes, Cj^Hj,(NH2), by reduction.

Two phenanthrene-sulphonic acids, CjjHg.SOjH, are produced on digesting
phenanthrene with sulphuric acid. If these be distilled with yellow prussiate of
potash we obtain two cyanides, Cj^Hg.CN, yielding the corresponding carboxylic
acids.

Phenanthraquinone, CiiHgOj, an ortho-diketone (see above),
is formed in the action of chromic acid upon phenanthrene in
glacial acetic acid solution ; most readily by heating it with a
chromic acid mixture {Annalen, ig6, 38). It crystallizes from
alcohol in long, orange-yellow needles, melts at 198°, and distils
without decomposition. It is not very soluble in hot water or cold
alcohol, but readily in hot alcohol, ether and benzene. It dissolves
in concentrated sulphuric acid with a dark green color, and is re-
precipitated by water. By adding toluene containing thiotolene
and sulphuric acid to the acetic acid solution of phenanthraquinone
a bluish-green coloration is produced (p. 572).

Like /3-naphthoqiiinone phenanthraquinone is odorless, not volatile in steam,
and is readily reduced by sulphurous acid. Like the latter, too, it unites with one

926 ORGANIC CHEMISTRY.

and two molecules of H2N.OH. The monoxime, Ci4HgO(N.OH), consists of
golden yellow needles, melting at 158°, and dissolving with a red color in sul-
phuric acid. If it is heated together with glacial acetic acid and hydrochloric acid
to 130° it sustains the transposition of keloximes (p. 727), and forms dipheni-

mide, CijHg^ p^>NH {Berichie, 22, Ref S91). The dioxime forms an anhy-

dride, Cj^Hg^ ^i>0, melting at 181°. An isomeric monoxime or dioxime has

not been prepared (p. 727) (^Berichte, 22, 1985).

Phenanthraquinone forms phenazine derivatives with ortho-diamines. Being
a ketone it also combines with primary sodium sulphite to form the crystalline
derivative, Cj^HjOj.SOjHNa + 2HjO, from which it is again separated by
alkalies or acids. By oxidation with chromic acid, or by boiling with alcoholic
potash, phenanthraquinone is oxidized to diphenic acid; ignition with soda-lime
produces diphenylene ketone (p. 851), fluorene and diphenyl. Diphenylene
glycoUic acid (p. 851), fluorene alcohol and diphenylene ketone are obtained on
boiling with aqueous soda-lye. Ignited with zinc dust we obtain phenanthrene.

On digesting phenanthraquinone with concentrated sulphurous acid it changes
to Dioxyphenanthrene, Cj^H8(OH)2 (phenanthrene hydroquinone), which
crystallizes from hot water in colorless needles that turn brown on exposure, and
reoxidize to phenanthraquinone. The diacetate crystallizes from benzene in
plates, melting at 202°.

By saponifying the two phenanthrene cyanides we obtain two Phenanthrene-
carboxylic Acids, CuHj^Oj : —

CgM^.CH CgIi..CH

(a) I II and (/3) | ||

CO2H— CgHj.CH CeHi.C.COjH.

The a-acid melts at 266°, and is oxidized to phenanthraquinone carboxylic acid,
CjjH,(02)C02H, by chromic acid; the j8-acid melts at 251°, and yields
phenanthraquinone.

Retene, CjgHjg, is a derivative of phenanthrene. It represents a methyl
isopropyl phenanthrene (Berichle, 18, 1027; Ref 558): —

*-3"-7/ II '-'3"?/ I I

CeH^.CH CpH^.cd

Retene. Retene Quinone.

Retene occurs in the tar of highly resinous pines, and in some mineral resins.
It is isolated from those portions that boil at elevated temperatures. It is very
soluble in alcohol and benzene. It crystallizes in leaflets with mother-of-pearl
lustre, melts at 98°, and boils about 390°. It is very volatile in steam. Its picric
acid compound forms orange-yellow needles, melting at 123°. Chromic acid in
glacial acetic acid solution oxidizes retene to retene quinone, CjjHjgO, (see
above) — a red powder, crystallizing in orange-red needles that melt at 197°- It
dissolves in caustic potash with a dark-red color ; this disappears upon shaking in
contact with air. It yields retene by the distillation with zinc dust. It resembles
phenanthraquinone in its entire deportment. It is an orthodiketone. Sulphurous
acid reduces it on application of heat to Retene Hydroquinone, Cj3H5(OH)3 ;

J^ /CO, which can be more easily prepared by distilling retene

FLUOR ANTH ENE. 927

air reoxidizes it to retene quinone. Hydroxylamine converts it into a quinone
oxime, CigHj50(N.0H), and quinone dioxime, C]gHj5(N.OH)2, golden yellow

leaflets, that melt at 129°. It forms retene phenazine, CigHjjf ?;^CjH^)
(p. 629) with o-phenylenediamine. ^

Sodium hydroxide converts retene quinone into two rather unstable acids —

Retene Diphenic Acid, C^Hi /^^z^, and Retene Glycollic Acid, C15H15.

CH(0H).C02H (see p. 851). Potassium permanganate oxidizes retene
quinone to diphenylene ketone dicarboxylic acid (p. 852) and retene ketone,
CH3.(C3H,).C,H,^

C,

quinone with lead oxide. When the latter is distilled with zinc dust the product
is retene fluorene, Ci,Hjj (p. 851). Pearly leaflets, melting at 97° (Berichte,
18, 1754).

Retene Dodecahydride, CjjHgj, a blue fluorescent oil, boiling at 336°
{^Berichte, 22, 780), is formed when retene is heated with hydriodic acid and
phosphorus to 250°. It is identical with dehydrofichtelite.

Fichtelite, C, jHjj, occurs together with retene in the peat of fossil pines. It
crystallizes from ligroine and alcohol in vitreous prisms. It melts at 46° [Berichte,
22, 498, 635). When heated to 150° wilh iodine it loses two hydrogen atoms
and forms Dehydrofichtelite, CigHjQ, identical with retene dodecahydride.
Fichtelite is, therefore, retene perhydride, CjgHgj [Berichte, 22, 3369).

Besides the hydrocarbons with high boiling points which have
been derived from coal-tar and already described ; naphthalene,
CloHs (B. P. 2x8°); methyl-naphthalene, CuH],, (240°); acenaph-
thene, C12H10 (278°) ; fluorene, C13H20 (305°) ; phenanthrene, CuHio
(340°), and anthracene, CkHjo (360°), we have the following :
fluoranthene, CjsHio, pyrene, CisHi,,, and chrysene, CigHi,. These
have been isolated from the so-called crude phenanthrene, the
fraction boiling above 360°.

Fluoranthene and pyrene occur chiefly in the first fractions. They are separated
by fractional distillation under diminished pressure ; fluoranthene boiling at 250°
under 60 mm. pressure ; pyrene at 260°. Their perfect separation is then effected
by the fractional crystallization of their picric acid derivatives [Annalen, 200, i ) .
The portions boiling at the most elevated temperatures consist mainly of pyrene
and chrysene, which are separated by means of carbon disulphide (which dissolves
pyrene) and by the crystallization of their picric acid combinations [Annalen, 158,
285 and 299).

Pyrene and fluoranthene (idryl) also occur in the " stubb-fat " obtained from the
distillation of the "stubb " (p. 924).

Fluoranthene, CjjHjq, Idryl,crystallizes from alcohol in needles or plates, melt-
ing at 109-1 10°, and dissolves readily in hot alcohol, ether and carbon disulphide.
It dissolves with a blue color in warm sulphuric acid. Its picric acid compound,
CjjHi |,.C5ll2(N02)30H, consists of reddish-yellow needles, is sparingly soluble in
ether, and melts at 182°. Fuming nitric acid converts idryl into the trinitro-com-
pound, Ci 5 H, (NO 2)3, melting above 300°. Fluoranthraquinone, CjjHgOj,
is obtained by oxidizing idryl with chromic acid. It crystallizes from alcohol in
small, red needles, melting at 188°, and dissolves, like phenanthrene, in alkaline
bisulphites. If the quinone be further oxidized (with elimination of COj) we ob-
tain diphenylene-ketone carboxylic acid.

928 ORGANIC CHEMISTRY.

The constitution of fluoranthene and of fluoranthoquinone probably corresponds
to the formulas (Annalen, 200, 20) ; —

CgH^. C5H4. CgH^.

I \CH I >CH I )C0

>CH=CH ^CC^ ^COjH

Fiuorarithene. Fluoranthoquinone. Diphenylene-ketone

Carboxylic Acid,

Pyrene, CjgHio.is sparingly soluble in hot alcobol (33 parls), readily in ether,
benzene and carbon disulphide, crystallizes in colorless leaflets or plates, and melts
at 148°. The picric acid compound crystallizes from alcohol in long needles, and
melts at 222°. Chromic acid oxidizes it to Pyrenquinone, C^H jOj, a brick-red
powder, which is almost completely decomposed when heated.

Pyrenic Acid, CjjHgOj, results upon further oxidation of pyrenquinone. It is
an ortho-dicarboxylic acid. It forms an anhydride or imide compound quite
readily. It consists of golden yellow leaflets, and at 120° breaks down into water
and its anhydride. Being a ketone it combines with one molecule of phenylhydra-
zine [Berichte, ig, 1997). When pyrenic acid is distilled with lime, it forms Py-
rene Ketone, C,2Hj(C0), crystallizing in yellow plates that melt at 141°. Being
a ketone, it combines with phenylhydrazine and sodium bisulphite. Potassium per-
manganate oxidizes pyrenic acid to naphthalene tetracarboxylic acid (p. 923), and
pyrene ketone to naphthalic acid, which yields naphthalene upon distillation with
lime.

Pyrene is, therefore, very probably a naphthalene, in which both peri-positions
(l, 8 and 4, 5) are replaced by two groups, CH.CH.CH, so that four symmetrical
condensed benzene nuclei are produced [Berichte, 20, 365 ; Annalen, 240, 147).

Chrysene, Cigllj^ (p- 927), is generally colored yellow (hence the name), but
can be rendered perfectly colorless by the action of different reagents. It is very
sparingly soluble in alcohol, ether and carbon disulphide, and rather readily soluble
in hot benzene and glacial acetic acid ; it melts at 250°, and boils at 436°. It
crystallizes and sublimes in silvery leaflets, which exhibft an intense violet fluores-
cence. The picric acid compound crystallizes from hot benzene in red needles, and
is decomposed by alcohol. When digested with chromic acid and glacial acetic acid
it oxidizes to so-called Chrysoquinone, CjjHjjOj (a diketone), which crystallizes
in red needles, melting at 235°, and dissolving in sulphuric acid with a blue color;
water reprecipitates chrysoquinone. It unites as a ketone with primary sodium
sulphite. Sulphurous acid reduces it to the hydroquinone, C,gHj„(0H)2.

Chrysoketone,Cj,Hj„0 (compare retene ketone), results when chrysoquinone
is distilled with lead oxide. It crystallizes in bright red colored needles, melting
at 152°. Hydriodic acid and phosphorus, upon application of heat, reduce it to
chrysofluorene, C,,Hj2 (melting at 187°).

Chrysenic Acid, Cj^HuOj (phenylnaphthyl carboxylic acid), is produced
when chrysene is fused with caustic alkali. It forms silver- white leaflets and melts
at 186°. When it is dissolved in sulphuric acid it reverts to chrysoketone [Be-
richte, 23, 2440).

Chrysene is prepared synthetically from benzyl-naphthyl-ketone, C^Hj.CH^.
CO.Ci„H, (from phenyl acetic chloride, CgH^.CHj-COCl, and naphthalene with
AICI3), if the latter be converted by heating with hydriodic acid and phosphorus
into the hydrocarbon, CgHs.CHj.CH^.CijHj, and then distilling this through a
red-hot tube — ^just as phenanthrene is produced from dibenzyl : —

+ 2H2.

PICENE. 929

Chrysene is similarly formed by heating naphthalene with coumarone, CjH^

y Q ^CHj— ^just as phenanthrene is obtained from coumarone and benzene (p.

924) {Berichte, 23, 84). Therefore, chrysene consists, in all probability, of four un-
symmetrical, condensed benzene nuclei; and chrysoquinone and chrysoketone
would then have the following formulas (see Berichte, 23, 2433) : —

I I >co.

. , - CO C^H^ ^

Chrysoquinone. Chrysoketone. ^

The liquid ^j/i/rii/,?, C J gH 2 8, boiling about 360°, is produced when chrysene is
heated together with hydriodic acid and phosphorus. A later product is Chrysene
Perhydride, CjjHjo, crystallizing in white needles, melting at 115° and boiling
about 353° [Berichte, 22, 135).

Naphanthracene, CjgHij, from naphanthraquinone, CigHjuO^, on digest-
ing it with zinc dust and ammonia, is isomeric with chrysene. It is produced by the
condensation of naphtoyl-tf-benzoic acid (from phthalic anhydride with naphtha-
lene and AICI3 p. 863) upon heating it with sulphuric acid, just as anthraquinone
is derived from (7-benzoyl-benzoic acid (p. 893) (^Berichte, ig, 2209) :

i

,CH CO /CO.C^H,

4\ I /"--lo^e "-'6'^4v /'-'io"^6 '-e^ix

^ch/ ^co^ ^co.oh

Naphanthracene, Naphanthraquinone. Naphtoyl-i7-benzQic acid.

Naphanthracene crystallizes from alcohol in colorless leaves, having a strong
greenish-yellow fluorescence. It melts at 141° and sublimes. It combines with
two molecules of picric acid, CjjH,2.2CgH3(N02)a0, forming red needles melt-
ing at 133°. Naphanthraquinone, CuHjdOj (see above), crystallizes and sub-
limes in yellow needles or leaflets and melts at 168°. It dissolves with a brown
color in concentrated sulphuric acid; water reprecipitates it unchanged.

Picene, C2 2Hj4, is a hydrocarbon formed by the distillation of lignite, coal-
tar and petroleum residues. It is very sparingly soluble in most of the solvents,
but most readily in crude cumene, crystallizes in blue fluorescent leaflets, melting
at 338°, and boils at 519°. It dissolves with a green color in sulphuric acid and
is oxidized by chromic acid to an orange-red quinone, C22H12O2. When heated
to 250° with hydriodic acid and phosphorus Picene Perhydride, C22H3g, is
produced. It forms white needles melting at 175° and boiling above 360° [Be-
richte, 22, 781).

DERIVATIVES OF NUCLEI CONTAINING NITROGEN.

A. Derivatives of five-membered nuclei containing nitrogen.

The five-membered parent nuclei and their derivatives were
almost entirely disposed of before the aromatic compounds were
taken up. Mention must, however, be made of the phenylated
diazoles : of pyrazole and oi glyoxaline (p. 551).
78

930 ORGANIC CHEMISTRY.

I. PHENYLATED PYRAZOLES.
The parent nuclei of the derivatives belonging to this class are : —

CH = CH, CHj— CHj. CHj-CO.

I ^NH I >NH I )NH.

CH = n/ I CH = N^ CH = n/

3 2

Pyrazole. Pyrazoline. 5-Pyrazolon.

The positions of substituting groups in these parent nuclei are designated by
the numbers 1-5, corresponding to the notation of the pyrazole nucleus. Pyrazo-
line and pyrazolidine (p. 551) bear the same relation to pyrazole as pyrroline and
pyrrolidine to pyrrol (p. S49). The nucleus of pyrazolon or ketopyrazoline, con-
taining oxygen, corresponds to pyrrolidon and the pyridine and lutidine of the
pyridine group (p. 944). The term j-pyrazolon serves to distinguish this from
the possible 3- and 4-pyrazolons, in which the oxygen occupies positions 3 and 4.

The pyrazole compounds (formerly called quinazine derivatives)
were discovered by L. Knorr in 1883 {Berichte, 16, 2597 j An-
nalen, 238, 137). Antipyrine belongs to this group. It has great
technical value.

I. Pyrazole-derivatives, in which oxygen is not present, are produced : —
(i) By heating the /3 diketones,* — CO.CHR.CO^ — of the benzene and paraffin
series with primary phenylhydrazines. The immediate products are the phenyl-
hydrazones (p. 656) ; these eliminate water and a closed ring results. Thus,
benzoyl acetone (p. 731) and phenyl hydrazine yield Diphenylmethyl Pyrazole
{Berichte, 18, 2135) : —

C5H5.CO.CH2.CO.CH3 -f HjjN.HN.CsH^ =

C.CH3

I + 2H,0.

N.C^H,

('» 3> s)-Diphenyl-methyl Pyrazole.

In like manner we obtain (\,'^,t^-phenyl dimethyl pyrazole,hom&cAy\ acetone,
CH3.CO.CH2.CO.CH3 {Berichte, 20, 1 104); and benzyl phenyl methyl-pyrazole
{Berichte, 18, 2137) from phenylacetyl acetone, CjHg.CHj.CO.CHj.CO.CHj
(P- 73')' (l> 3> S)- Triphenyl pyrazole is derived from dibenzoyl methane, CjHj.
CO.CHj.CO.CgHj (p. 891) {Berichte, 21, 1206).

Pyrazole carboxylic esters are formed in an analogous manner from /3-diketone
carboxylic esters. For example, benzoyl aceto-acetic ester (p. 816) and phenyl
hydrazine yield (i, 3, ^)-diphenyl methyl-pyrazole-^-carboxylic ester {Berichte, 18,
3"):—

* The y-diketones combine with the phenylhydrazines, forming pyridazine com-
pounds (p. 954), whereas the derivatives of the rt-diketones with two molecules of
phenylhydrazine remain unchanged.

PHENY^ATED PYRAZOLES. 93 1

C,H,.C0.Ch/^02^ + H.N.HN.C.H^ =

/ ^

-C^^C.CHg

CeHs-C/ I + 2H,0.

^5

hyl- , .
[^arboxylic Acid.

(i, 3, 5)-Diphenyl-methyl-4-pyrazole
Ca]

The corresponding nitro-derivatives {Berickte, i8, 2256) are similarly formed
from o- and /-nitro- benzoyl aceto- acetic ester. The free acid results upon saponi-
fying the ester; when it loses carbon dioxide it passes into (i, 3, 5)-diphenyl-
methyl-pyrazole (see above) {Berichte, 20, 1096). Under like treatment acetyl
aceto-acetic ester, CH8.CO.CH(CO.CH3).C02R, furnishes (1,3, 5)-phenyldimethyl
pyrazole-4-carboxylic ester, from which by saponification and elii;aination of car-
bon dioxide, it is possible to obtain (i, 3, 5)-phenyldimethyl pyrazole, C^HNj
(C5H5) (CHgjj [Berichte, zo, Iioi). Further, benzoyl pyroracemic ester C5H5.
CO.CHj.CO.COjH (p. 765), becomes diphenylpyrazole-carboxylic ester, which
then yields (l, 3)-diphenyl pyrazole, C^li^l^^^Cfi^^ (Berichte, 20, 2185).

2. The (3- or (i, 3)-ketone aldehydes react like the /3-diketones. Thus we obtain
from acetylaldehyde, CHj.CO.CHjCHO, (l, ^)-phenyl methyl pyrazole, from
propionyl aldehyde, CH3.CH2.CO.CHj.CHO, phenyl ethyl pyrazole {^Berichte,
11., 1147), from propionyl propionic aldehyde, CH3.CH2.CO.CH(CH3).CHO,
phenylmethylethyl pyrazole {^Berichte, 22, 3276), and from benzoyl aldehyde,
C5H5.CO.CHj.CHO (p. 730), (I, ^)-diphenylpy?-azole {Berichte, 21, I138), etc.

Epichlorhydrin conducts itself in a similar manner with the formation of l-phenyl-
pyrazole, which may also be prepared from phenyl pyrazole tricarboxylic acid
(^Berichte, 22, 180, Ref 238, 554). It is a yellow oil; when it has been solidified
it remelts at 11° and boils at 246°.

3. From the unsaturated ketones and aldehydes, CHR:CR.COR and CHR:CR.
COH, when they are heated with the phenylhydrazines. The phenylhydrazine
formed at first loses, when distilled, two hydrogen atoms, and yields the correspond-
ing/jraxa/if derivative; iht pyrazoline compound, isomeric with the latter, is formed
simultaneously by mere molecular re-arrangement of the phenylhydrazone (An-
nalen, 238, 14I ; Berichte, 20, 1097). In this way benzal acetone, CH3.CO.CH:
CH.C3H5 (p. 805) and phenylhydrazine form (l, 5, '^■diphenylmethyl pyrazole
z-nA pyrazoline [Berichte, 20, 1 100) : —

CH3.C— CH =r CH.CjHs CH3.C.CH2— CH.CjHj

II yields II I

N— NH.CgHj N N.C.Hj

Phenylhydrazine-benzal Diphenylmethyl

Acetone, Pyrazoline.

CHg.C CH = C.CgHg

and II I -f Hj.

N N.C.Hj

Diphenylmethyl
Pyrazole.

The latter is isomeric with (i, 3, 5)-diphenylmethyl pyrazole. Under similar
treatment ethidene acetone, CHj.CO.CHrCH.CHj (p. 195), yiAAs phenyl dimethyl-
pyrazoline [Berichte, 22, 1105). Cinnamic aldehyde forms (l, ^)-diphenylpyrazo-
line, and (i,;^,e,ytriphenylpyrazoline\s obtained from benzalacetophenone, C5H5.
CH:CH.C0.CgH5 [Berichte, 21, 1201).

Pyrazole carboxylic esters are similarly derived from unsaturated ketone car-
boxylic acids (their esters) ; the pyrazoles can be prepared from these. Thus,

932 ORGANIC CHEMISTRY.

benzal aceto-acetic ester and phenylhydrazine yield (l, 5, -^-diphenyl methyl pyra-
zole-^-carboxylic-ester : —

/CO^H

CH3.CO.C = CH.C.Hj + H.N.NH.CsHj =

/CO,H-

CH3.C C =^ C.CgHe

I + H,0 + H^-

Diphenylmethyl-pyrazole
Carboxylic Ester.

(i, s,3)-Diplienylmethyl-pyrazole (see above) results upon saponifying the ester
and eliminating carbon dioxide (Annalen, 238, 139). Ethidene aceto acetic ester
yields (i, 3, 5)-plienyldimetliyl-4-carboxylic ester ; when this is saponified and loses
carbon dioxide it forms (l, 3, 5)-phenyldimethyl-pyrazole [Berickte, 22, lioi).

The unsaturated aldehydes react very much like the unsaturated ketones. Acro-
lein-phenylhydrazide yields l-phenyl pyra%oline {Annalen, 239, 195) : —

CH— CH=CH, CH.CH^.CIIj

II = II I .

N— NH.CgHj

The phenyl pyrazoles axe feeble bases ; water readily decomposes their salts;
they volatihze with steam from acid solutions. Nitrous acid does not affect them.
Sodium, acting upon their alcoholic solution, converts them into the corresponding
pyrazolines. The latter are also weak bases ; oxidizing agents (nitrous acid,
chromic acid and ferric chloride) convert thera into fuchsine red dyes— /j)/''o«"/i?
reaction of Knorr {Annalen, 238, 200).

2. The oxygen-containing /_y?-o«o/o»derivatives (see above) are produced, if
;3-ketonic acids, R.CO.CH2.C02H,be substituted for /3-diketones in the formation
of the phenylpyrazoles, or if, instead of unsaturated ketones, aldehydes and ketone
carboxylic acids, unsaturated acids be allowed to react with phenylhydrazines.
Acetoacetic ester and phenylhydrazine condense to ahydrazone, which, upon being
heated, splits off alcohol and forms (Xj'^-phenyl-methyl pyrazolon [Annalen, 238,
146) :—

CH..C— CHj— CO

II I +C,H,.OH.

N— NH.C^Hs N N.CsHe

Phenylhydrazine Aceto-acetic Ester. (i, 3)-Phenylmethyl Pyrazolon.

«
(I, 3)-Diphenylpyra2olon is similarly formed from benzoyl acetic ester, CgHj.
CO.CHj.COj.CjHj {Beriehie, 20, 2^4^ ; 21, Ref. 201). The phenylhydrazide
of unsaturated phenylacrylic acid, C5H5.CH:CH.CO.NH.NH.C„H5, when dis-
tilled, loses two hydrogen atoms and forms (i, 5)-Diphenylpyrazolon, CjjHjj
N^O = Ci^H^^N'zO + H2 (JBerich/e, 20, 1107). Oxalylacetic ester (p. 435)
{Berichte, 19, 3227) and succino-succinic ester (p. 795) {Berichte, 17, 2053) re-
act analogously. The ester of phenylformyl acetic acid (a ^-aldehydic acid) reacts

PHENYLDIMETHYL PYRAZOLON. 933

similarly to the esters of /3-ketonic acids with the formation of (i, 4)- diphenyl-
pyrazolon {Berichte, 20, 2933) : —

.CO.O.CaHj
CeHj.CH^ + H,N.HN,C,H,=

Phenylformyl Acetic Ester.

,C0. N.CjHj
C,H,.CH( I + C.Hj.OH + H,0.

(i, 4)-Diphenyl pyrazolon.

As the CHj-group of the pyrazolon compounds, obtained from acetyl- and ben-
zoyl-acetic esters, is retained unaltered, all mono- and di-substituted acetoacetic acid
esters ( e.g., methyl- and dimethyl- acetoacetic ester, acetosuccinic ester, etc.), are
capable of yielding pyrazolon compounds with primary phenylhydrazines. On the
other hand, the unsymmetrical /3-conipounds (not the a-derivatives, p. 657), from
the alkylic phenylhydrazines, are able to form derivatives of the isopyrazolon nu-
cleus (antipyrine compounds). Tolylhydrazine, naphthylhydrazine, etc., react in
the same manner as phenylhydrazine [Berichte, 17, 549). Hydrazobenzene, CgHj.
NH.NH.CgHj, reacts just the same as the /3-alkyl phenylhydrazines (p. 649).

(i, 3)-Phenylmethyl Pyrazolon, C3H20(CH3)N2(C6H5 =
C10H15N2O, resulting from acetoacetic ester and phenylhydrazine
{Annalen, 238, 147), crystallizes from hot water in prisms, melting
at 127° and boiling at 287°. It manifests the feeble basic character
of the pyrazole bases, and at the same time the acid nature of
acetoacetic ether. It is soluble in acids and alkalies. The hydro-
gen of its CHj-group will answer all the reactions of the same
group in aceto-acetic ester; it can be replaced by metals, alkyls,
etc. Ferric chloride or platinic chloride oxidizes the pyrazolon to
pyrazole blue (see below). This reaction serves for the recognition
of all pyrazolon compounds containing the CHj-group intact.

When (i,-3)-phenylmethyl pyrazolon is heated to ioo° with me-
thyl iodide and methyl alcohol, it sustains a partial transposition
and forms

Phenyldimethyl Pyrazolon, CnHi^N^O = C3H(CH3)2N2(C6
H5)0 (i, 2, 3), Antipyrine. This is derived from the unaltered iso-
pyrazolon nucleus (with a different arrangement of the hydrogen
atoms), and may be directly synthesized by heating acetoacetic
ester with a-methyl-phenyl-hydrazine, C6H5.NH.OH.CH3 (see
below) {Annalen, 238, 160, 203; Berichte, 20, Ref. 609) : —

CH,.CO.CH„.CO.O.C„H5 + CH3.NH.NH.C5H5 =

CH3.C = CH.CO

\ I + C2H5.OH -f H,0.

CHs— N N.CjHj.

Antipyrine.

Antipyrine, rather singularly, is very soluble in water, alcohol
and chloroform. It crystallizes from ether and toluene in shining
leaflets, melting at 113°. It is a strong monacid base, that forms

934 ORGANIC CHEMISTRY.

salts with ease. Ferric chloride colors its aqueous solution red, and
nitrous acid imparts a bluish-green color to it {Annalen, 238, 263).
It is used as an antipyretic.

Many derivatives are obtained by the substitution of the hydrogen of the CH^
group in phenylmethylpyrazolon. Compounds like benzylidene-phenylmethyl-
pyrazolon are formed upon heating it together with aldehydes. These are red
dye-substances. They correspond to the indogenides of pseudoindoxyl (p. 833).
Bi-phenylmethyl Pyrazolon is formed by moderated oxidation or by the action of
iodine upon silver phenylmethyl pyrazolon. It can also be obtained synthetically
from diaceto-succinic ester, and tvfo molecules of phenylhydrazine. Pyrazole
Blue {^Annalen, 238, 171) is even formed in the cold by further oxidation vvith
ferric chloride, etc. ; —

.CO— CH CH— CO,

C,H,.N( I \ )N.CeH,.

\N = C.CH3CH3.C = N^

^i-(i» 3)" Phenylmethyl Pyrazolon.

-CO— c c-co .

CeH,.N( I I >N.C,H,.

^N = C.CH3CH5.C = n/

Pyrazole Blue.

Pyrazole blue results directly upon boiling phenylmethylpyrazolon with ferric
chloride. In properties and constitution it is very similar to indigo blue.

Phenylmethyl pyrazolon exhibits great similarity also to barbituric
acid (malonyl urfea, p. 441). Its isonitroso-, nitro- and amido-
derivatives correspond perfectly to violuric acid, dilituric acid, and
the uramile of the uric acid group. When the amido group is oxid-
ized rubazonic acid is produced ; this corresponds to purpuric acid
{Annalen, 238, 192). Rubazonic acid and phenylhydrazine unite
to a hydrazone, that is identical with an azo-compound derived from
phenylmethyl pyrazolon and benzene diazochloride {Berichte, 21,
1201).

2. PHENYLATED GLYOXALINES (p. 929).

The alkyl glyoxalines have been discussed. The phenylated
glyoxalines will be here considered. Lophine, CjiHieNj, and
Amarine, CijHisNj, belong in this class. They are triphenyl deri-
vatives of giyoxaline and dihydroglyoxaline, and bear a close rela-
tion to hydrobenzamide (p. 717) and triphenyl-cyanide, (C6H5.CN)3
{Berichte, 18, 1849, 3°8s) : —

C.H^CaN C^H^.C-NH. CeH^.C.NH,

>CH.C,H, II )CH.CeH. || \c.C,\\,.

C,H,CH:N/ . CeH,.C.NH/ C3H,.C.NH^ ' '

Hydrobenzamide. Amarine. Lophine.

Triphenyl Giyoxaline, C3N2H(C6H5)3, Lophine, is produced
when amarine or hydrobenzamide is subjected to distillation, or if
the former be oxidized with chromic acid (in glacial acetic acid),

PHENYLATED GLYOXALINES. 935

or from cyanphenine, (CeHs.CN),,, by the action of nascent hydro-
gen (with disengagement of NH3). It may be prepared syntheti-
cally by acting with ammonia upon an alcoholic solution of benzil,
with benzaldehyde, in the same manner as glyoxalethylins are ob-
tained from glyoxal with aldehydes (p. 552). Lophine is not
readily soluble in alcohol, crystallizes in long needles, and melts at
275°. It yields crystalline salts with one equivalent of the acids.
It exhibits the property of phosphorescing in marked degree when
shaken with alcoholic potash ; it is then decomposed into ammonia
and benzoic acid (p. 189). Like the glyoxalines, it does not form
an acetate.

Triphenyl Dihydroglyoxaline, C3N2H3( €6115)3, Amarine, re-
sults from a rearrangement of the isomeric hydrobenzamide, caused
by boiling it with caustic potash or upon heating it to 130°. It
crystallizes from alcohol and ether in prisms, melting at 113°. It
reacts (in alcoholic solution) alkaline, and with one equivalent of
the acids yields salts which are sparingly soluble in water. Amarine
affords dialkyl derivatives when it is heated with alkyl iodides,
whereas only mono-alkyl compounds result with lophine.

3. PHENYLATED TRIAZOLES (p. 553).

CH = N. N = CH.

I >NH, Osotriazone. | • ^NH, Triazole.

CH = n/ CH = N/

Triphenyl Osotriazone, C2N3(C6H5)3, from benzil dihydra-
zone, consists of pearly leaflets, melting at 122" (jBerichte, 21,
2806).

The diketo derivatives of Tetrahydrotriazole, C2N3H7, have
been called urazoles (p. 553).

In conclusion,mention must be made of the biazole ring. Its phenyl

derivatives, formerly termed phenyl carbizines, Q,^/, \ /CX,

and considered such, result in the action of phosgene gas upon the
a-acid or urea-derivatives of the phenylhydrazines {JBerichte, 21,
2456; 23, 2843):—

C5H5.NH.NH.CO.CH3 + COCI2 = C5H5.N — N

n-Acetylhydrazine. | [| -|- 2HCI.

CO CCHj
\/
P

Phenylmethyl Biazolon.

936 ORGANIC CHEMISTRY.

Phenyl Biazolon, CeHs.CjNjOjH, is analogously formed from
formyl phenylhydrazine (p. 658), and was formerly designated
formylphenyl carbizine. It melts at 73° and boils at 255°.
Phenyl Methyl Biazolon, CeHj.QNjOz.CHs (see above), melts
at 94° and boils at 280°.

The phenyl biazolons are quite stable towards acids, even when
heated with the latter. Boiling alkalies decompose them into their
components.

B. Derivatives of six-membered Nuclei, containing Nitrogen. Pyri-
dine and Quinoline Group.

Pyridine, C5H5N, and Quinoline, CgHjN, are two basic bodies,
which command particular interest, because they have been recog-
nized as the parent substances of many alkaloids. In their entire
deportment they closely resemble the benzene compounds. They
are quite stable towards oxidizing agents (nitric acid, chromic
acid, potassium permanganate). By replacing the hydrogen in
them with alkyls (especially methyls) they yield a series of homo-
logous compounds — the Pyridine and Quinoline bases, e. g. , CsH^
(CH3)N, and C6H3(CH3)2N, from which the acids (mono-, di- and
tri-carboxylic acids) result on oxidizing the methyl groups. By
elimination of the carboxyls from the acids, the stable parent
nuclei, pyridine and quinoline, are regenerated. This deportment,
characteristic of benzene compounds, is explained by the constitu-
tion of pyridine and quinoline. Both contain a closed chain con-
sisting of five carbon-atoms and one nitrogen-atom. This ring is
remarkably stable, and is very similar to the benzene ring.

Pyridine, C5H5N, may be regarded as a benzene in which one CH-group is re-
placed by a nitrogen-atom; whereas quinoline, CgH,N, is derived in a similar
manner from naphthalene, Ci„Hg, by a change in one of the benzene rings : —

H H H

C C C

^ \ // \/ \

HC CH - HC C CH

HC CH HC C CH

% / %/\ ^

C N C

Pyridine. H

Quinoline.

These constitutional formulas have been proved by numerous syntheses of
pyridine and quinoline, as well as of their derivatives (Korner, 1869). The forma-
tion of pyridine from quinoline is rather remarkable. The latter is oxidized, the
benzene nucleus is destroyed (as with naphthalene, p. 907) the a- /3-pyridine-

PYRIDINE GROUP. 937

dicarboxylic acid, C5H3N(C02H)2, formed, and when it splits off 2CO2 pyridine
is produced : —

CH = CH— C— CH = CH CH = CH— C— CO,H CH = CH— CH

I II I I I 1 II

CH = N — C— CH = CH CH = N — C— CO^H CH = N — CH

Quinoline. Pyridine Dicarboxylic Acid. Pyridine.

Since the nitrogen-atom in the pyridine and quinoline bases is
joined with three affinities to carbon, these compounds are tertiary-
amines, which combine with alkyl iodides, yielding ammonium
iodides. Further, it follows, from the accepted structural formulas,
that the pyridine and quinoline derivatives are capable, like ben-
zene, of yielding hydrogen addition products; thus from pyridine,
we obtain a hexa-hydride, C6H5(He)N, identical with the alkaloid
piperidine, CjHnN = C5H,o:NH.

Many of the transpositions of the pyridine nucleus, and the methods employed
in its formation find their simplest explanation in the fact that the nitrogen atom
present in the nucleus is in direct union with the carbon atom opposite to it
(occupying the para position), as indicated in the formulas : —

CH CH CH

/

HC

\
CH

Hi

II
CH

\

I

Pyri

iine.

HC

and

HC
\

\ / ^

C CH

C CH

/ \-^

N CH

Quinoline.

(See BeHchte, 17, 2871 ; 20, 801 ; 21, 1967). It is undetermined whether
these prismatic or diagonal formulas are isomeric or tautomeric with the preceding
ring-shaped formulas (as in analogous cases). In schemes showing the manner of
union of the atoms in pyridine and quinoline — schemes analogous to the benzene
hexagon — this difference disappears.

I. PYRIDINE GROUP— C,H,„_5N. *

PYRIDINE, C5H5N.

Picolines— C6H,N = C5H,(CH3)N— Methyl pyridines.
Lutidines — QHgN = C5H3(CH3)2N — Dimethyl pyridines.
Collidines— CsHuN = C5H2(CH3)3N— Trimethyl pyridines.

The following bases, isolated from coal-tar, have not been well studied and are
included here: Parvoline, CgHijN (B. P., 188°), Corindine, CioH^N (at
211°), and Rubidine, C^HjjN (at 230°).

*Buchka, Die Chemie des Pyridins und seiner Derivate, 1890.

938 ORGANIC CHEMISTRY.

The pyridine bases arise in the dry distillation of nitrogenous
carbon compounds and occur simultaneously with the quinoline
bases in coal-tar (along with the isomeric anilines) and especially
in bone-oil.

To obtain the pyridine bases from Dippel's oil (p. 539), concentrate the dilute
sulphuric acid solution (when any pyrrol which has dissolved will be volatilized
or resinified), separate the pyridine bases by means of concentrated sodium hy-
droxide, dehydrate them with caustic soda and subject the product to fractional
distillation [Berichte, 12, 1989). At present the pyridine bases are mainly
obtained from coal-tar i^Annalen, 247, i). They occur in the "purifying acid,"
from which they can be easily isolated {^Berichte, 20, 127; 21, 1006).

Again, the pyridines, as well as quinoline bases, are obtained by
the distillation of the alkaloids (cinchonine) with caustic alkali, or
by oxidizing the quinoline bases and alkaloids to pyridine carboxylic
acids, e.g., C5HaN(C02H)2, which split off carbon dioxide (see
above) and yield pyridines.

Synthetic methods for the production of the pyridines : —

(1) ^-Methyl Pyridine, C5H^(CH3)N, is prepared from acrolein-ammonia,
CgH9.NO, by elimination of water (p. 199), or by heating trichlor- or tribrom-
allyl with alcoholic ammonia to 250°, and from glycerol and acetamide by heating
with PjOj {Berichte, 18, 3094) : —

2C3H,0 + NH3 = C,H,(CH3)N + 2H,0.

(2) (I, 4)-Methyl Ethyl Pyridine, C5H3(CH3)(C,H5)N, aldehyde collidine,
aldehydine (p. 943), resulis when ethidene chloride or bromide is heated with
alcoholic ammonia (Berichte, 18, 920), from aldehyde by the rearrangement of
the oxyietraldine formed at first, but most readily from aldehyde ammonia upon
healing It with paraldehyde [Berichte, 20, 444) : —

.# 4C,H,0 + NH3 = C,H3 (CHs J N + 4H,0.

A methyl propylpyridine is analogously obtained from propionic aldehyde and
acetamide [Berichte, 21, 279).

(3) The fact that chlor- and brom-pyridine can be produced by heating potas-
sium pyrrol with CHCI3 and CHBr, is of interest. Pyrrol and sodium ethylate
may be used as a substitute for potassium pyrrol [Berichte, 18, 723). Pyridine
results if CH^I^ be used [Berichte, 18, 3316) ; and with benzal chloride the pro-
duct is ^-phenylpyridine [Berichte, 20, 191). Pyridine and alkylpyridines
[Berichte, ig, 2196) are similarly formed from a- and j3-alkylpyrrols, C4H3R.NH
(p. 540) upon digesting them with concentrated hydrochloric acid. In all these
reactions the entering C-atom assumes the ^-position relatively to the pyrrol
nitrogen [Berichte, 20, 194). The reaction occurs more readily by using pyrrol-
carboxylic acid [Berichte, 21, 2856). Alkyl indols sustain similar transpositions;
quinoline derivatives result.

(4) A very ready synthesis of the pyridine nucleus occurs upon heating penta-

PYRIDINE GROUP. 939

methylene diamine hydrochloride (p. 313) ; piperidine (hexhydropyridine) is pro-
duced (Ladenburg, Berichte, 18, 3100) : —

/CHj— CH2.NH2 .CH2— CHj,

CHjC; . + HCl = CH / )NH + NH^Cl.

^CH^— CH2.NH2 ^CH^— CH^/

Pyridine is formed when the piperidine is heated with concentrated sulphuric
acid. Six hydrogen atoms are eliminated (p. 951). Trimethylenediamine yields
trimethylenimine and /3-methylpyridine {Berichte, 23, 2727).

(s) A method frequently pursued in synthesizing pyridine deriv-
atives consists in the condensation of acetoacetic ester with an
aldehyde-ammonia, or with an aldehyde and ammonia. This leads
to the formation of dicarboxylic esters of alkyl dihydropyridines.
Reaction of Hantzsch {Annalen, 215, i ; Berichte, 18, 2579).

(i, 3, 5)-Triinethyldihydropyridine-dicarboxylic Ester (dihydrocoUidine
dicarboxylic ester), C5H2N(CH3)3(C02R)Jr forms upon digesting acetoacetic
ester (2 molecules) with aldehyde ammonia (l molecule), or with acetaldehyde
and ammonia : —

CHg CHg

RO^C.CH^ I I

I CHO CH^.COjR RO2C.C— CH— C.CO2R

CH3.CO J = II II +3H2O.

NH3 CO.CH3 CH3.C— NH— C.CH3

The entering aldehyde radical takes the para-posftion relatively to nitrogen {Be-
richte, 17, 1521). The three methyls occupy the positions (l, 3, 5), the two car-
boxyls are in (2, 4) {Berichte, 18, 1745). The two added hydrogen atoms are in
union with the nitrogen and the 7-C-atoms {Berichte, 18, 2579 and 620). Nitrous
acid oxidizes the dihydro compound to the ester of normal Trimethyl-pyridine-
carboxylic Acid, C5N(CH3)3(C02R)2 ; this yields a series of pyridine deriva-
tives.

The reaction proceeds in a perfectly analogous manner with propyl aldehyde,
isobutyl aldehyde, »-butyl aldehyde and valeric aldehyde, with the formation of
dimethyl alkyl derivatives, C5H2N(CH3)2R(C02R)2 (Benchte, 21, Ref. 638).
The aromatic aldehydes behave in the same way ; benzaldehyde affords dimethyl-
phenyl-dihydropyridine dicarboxylic ester {Berichte, 17, 1515). Cinnamic ald.f:
hyde {Berichte, ig, Ref. 18) and OT-nitrobenzaldehyde react likewise. Primary
amines act the same as ammonia ; it is very probable that »-alkyl derivatives are
produced in such cases. The ammonia can also be attached to acetoacetic ester.
Paramidoacetoacetic ester {2 molecules), paraldehyde (i molecule) and a little
sulphuric acid form (i, 3, S)-trimethyl-dihydropyridine-dicarboxylic ester: — 2C5
HiiNOj + CjH^O = C14H21NO4 -I- NH3 + HjO. On heating the para-amide
ester alone, or its hydrochloride, we get oxy-dimethyl pyridine-monocarboxylic
ester, C5H20N{CH3)2.C02R, which, by the loss of the carboxyl group, forms
pseudolutidostyril (p. 945) {Berichte, 21, 445).

Aceto-acetic ester reacts in the same manner with hexamethylenetetramine as
with aldehydes and ammonia, the products being hydrolutidine dicarboxylic esters
{Berichte, 21, 2740).

6. In Hantzsch's reaction one molecule of acetoacetic ester can be replaced by
one molecule of aldehyde, the products then being dialkylmonocarboxylic esters.
Thus, we obtain (i, 3)-Dimethyl Pyridine-2-Carboxylic Ester {Berichte, 18,

940 ORGANIC CHEMISTRY.

2020) on mixing acetoacetic ester (i molecule) with aldehyde ammonia and acet-
aldehyde (i molecule each) : —

CHq CHq

I I

CHj CHO CHj.COjR CH— C=C.C02R

I I = II I +3H,0 4-H,.

CHO NH3 CO.CH3 CH— N=C.CH3

Ester of Lutidine Carboxylic Acid.

7. The pyrone derivatives (p. 958) may be rearranged to pyridine and oxy-
pyridine compounds by heating them together with ammonia. This is an inter-
esting reaction.

8. The rearrangement of acetone dicarboxylic ester by means of ammonia into
oxyamido-glutaminic ester and glutazine, a derivative of trioxypyridine, is based
upon analogous reactions [Berichie, ig, 2708; 26, 2655) : —

co<ch::c8::c:h: c(oh)(nh,)<:^h,.co.nh^^

C(NH)(^H.CO\j,H_

Dioxypyridine carboxylic acid (citrazinic acid) (p. 947) is produced in a similar
manner from citramide upon digesting it with sulphuric acid : —

.CH2.CO.NH2 /CHj.COX

C(0H)(C0.,H)( yields C^CO^H) N + H.O+NH,.

^CHj.CO.NHj XCH^.CO/

The pyridine bases are colorless liquids with a peculiar odor.
Pyridine, C5H5N, is miscible with water. The solubility of the
higher members grows rapidly less. They form crystalline salts with
one equivalent of the acids. They form double salts with mercuric
and auric chlorides ; these serve for the separation of the individual
bases {Annalen, 247, i). They are attacked with difficulty when
boiled with nitric or chromic acid, and by this behavior are easily
distinguished from the isomeric anilines. In the homologous pyri-
dines, however, the alkyls are oxidized to carboxyls by a potassium
permanganate solution.

The pyridines combine, as tertiary bases with the alkyl iodides, yielding ammo-
nium iodides {Berichte, 18, 591). The ammonium hydroxides, obtained from the
latter by nreans of silver oxide, sustain a comphcated decomposition when exposed
to heat. Consult Berichte, 17, 1027, ig, 31, upon the deportment of the ammo-
nium hydroxides of the pyridine-carboxylic acids.

If the ammonium iodides be heated with caustic soda, an extremely pungent
odor is developed — Reaction for the pyridine bases [Berichte, 17, 1908). Someof
the pyridines yield hydrides with nascent hydrogen (p. 937) ; their ammonium
hydroxides are decomposed by further reactions into trimethylamine and a hydro-
carbon (see piperidine and conine).

PYRIDINE. 941

Pyridine heated with hydriodic acid to 300°, yields normal pentane, C5H12,
and collidine, under the same treatment, yields normal octane {Berichte, 16, 591).
Metallic sodium causes the pyridines to undergo a peculiar polymerization, and
they then yield dipyridine bases.

Isomerides.

The derivatives produced by the replacement of the hydrogen atoms in pyri-
dine can easily be deduced in their possible isomerisms from the given structural
formulas (p. 937), and are perfectly analogous to the isomerisms of the benzene
derivatives. Representing the five hydrogen atoms, or the affinities of the pyri-
dine nucleus, with numbers or letters, corresponding to the diagram —

, 2 I I a

iTr/CH = CH\„ / \„

4 5 /3' «'

then the positions, 1 and 5, also 2 and 4 (as in benzene), are similar (p. 560).
The first may be designated the ortho-, the latter, the meta-positions — while the
position 3, occurring only once, corresponds to the para of benzene. From this
we conclude, that the mono-derivatives of pyridine, C5H4(X)N, can exist in
three series, while six isomerides are possible with the di-derivatives C5H3{X2)N.
This is verified by the existence of three methyl, three propyl- and phenyl-pyri-
dines, C5Hj(R)N, of three pyridine-mono-carboxylic acids, C5Hj{C0jH)N, of
six dicarboxylic acids, etc. For practical reasons the isomerides are called a-, /3-,
and /-derivatives, corresponding with the second diagram. a-Pyridine carboxylic
acid (picolinic acid) corresponds to the position i ; the /3-acid (nicotinic acid) to
the position 2, and the 7-acid (isonicotinic acid) to position 3. This determination
of place for the pyridine derivatives is evident from the manner in which the
three phenyl pyridines, C5H4(CsH5)N, are produced, the a- and /3- being derived
from the two naphthoquinolines. See Skraup, Monatshefte fiir Chemie, IV,
437, 59S and Berichte, 17, 1518; 18, 1745.

The behavior of the pyridine dicarboxylic acids, C5H3N(C02H)2, leads to a
simpler deduction of the position of their atoms (Ladenburg, Berichte, 18, 2967).
The ortho-position of a-oxypyridine is evident from the fact that it can be formed
by oxidizing carbostyril {^Berichte, Ig, 2432). Quinolinic acid (pyridine carboxylic
acid), formed by the oxidation of quinoline,has the position ( 1 , 2), and cinchomeronic
acid, from isoquinoline, has the position (2, 3). Quinolinic acid loses one molecule
of carbon dioxide when heated and forms nicotinic acid, while cinchomeronic acid
yields nicotinic acid and isonicotinic acid ; therefore nicotinic acid is ^ ^ 2 and
isonicotinic acid y =: 3.

Pyridine, C5H5N, can be prepared from bone-oil, and is obtained
from all the pyridine-carboxylic acids on distillation with lime. It
is a pungent-smelling liquid, miscible with water, of sp. gr. 1.0033
at 0°, and boiling at 114.8°. Its hydrochloride, C5H5N.HCI, is
deliquescent, and with platinum chloride it forms a double salt,
(C5H5N.HCl)2.PtCl4, that is rather insoluble. Sodium amalgam,
or better, sodium and alcohol, convert it into the hexahydride —

942 ORGANIC CHEMISTRY.

piperidine, C5H10N (p. 950), from which, vice versa, pyridine is
obtained by oxidation.

Pyridine forms ammonium iodides with allcyl iodides (p. 940). It combines
with chloracetic acid and yields Pyridine-betaine, C^ll^^{„ "' , corres-
ponding fully to ordinary betaine. The homologous pyridines yield analogous
betatnes {Berichte, 23, 2609).

Sodium converts pyridine into polymeric Dipyridine, CjuHj^Nj, an oil
boiling at 286-290° ; potassium permanganate oxidizes it to isonicotinic acid. At
the same time rather large quantities of /-Dipyridyl, CjoHgNj = NCjH^.CjH^N
(yy), are produced; this distils at 304°, sublimes in long needles, and melts at
1 14°. It crystallizes from water containing two molecules of water and melts at
73°. It is a di-acid base. Potassium permanganate oxidizes it to isonicotinic
acid. Isonicotine, Ci^Hj^Nj, is obtained from it by reduction with tin and hydro-
chloric acid. Isomeric OT-Dipyridyl, Cj^HgNj {y8/3), results from meta-dipyridyl-
dicarboxylic acid (from phenanthroline, p. 950), boils at 287°, and yields deliques-
cent needles, melting at 68°. Potassium permanganate oxidizes it to nicotinic
acid. Reduction with tin and hydrochloric acid produces nicotidine. A third
Dipyridyl (ao) has been prepared by the distillation of copper picolinate. It
melts at 70° {Berichte, 2i, 1077).

Substitution Products. — Pyridine and its homologues are substituted with diffi-
culty by the halogens [Berichte, 21, 1773). Nitro products have not been pre-
pared. Bromine acts more readily upon pyridine sulphonic and carboxylic acids,
especially upon the application of heat. The side-chains are then replaced
[Berichte, 20, 1343). ^-Chlor- and Brom-pyridine have been synthetically pre-
pared from pyrrol by means of chloroform, etc. (p. 938).

If pyridine (or piperidine) be heated with concentrated sulphuric acid to 330°,
or with fuming sulphuric acid we get ;3-Pyridine-sulphonic and disulphonic
acids, C5HjN(S03H), and C5H3N(S03H)2, which form needles that dissolve
without difficulty. ;8-Cyan-pyridine, CjH^N.CN, produced on distilling the
sodium salt with potassium cyanide, crystallizes in white needles, melts at 48-49°,
and by saponification yields nicotinic acid.

Homologous Pyridines.

The methylated pyridines occur in bone-oil and coal tar. They
are synthetically prepared by heating the pyridine-ammonium-
iodides to 300° (Ladenburg, Berichte, 17, 772) : —

C^HsN.C.H^I = C,H^(qH5)N.HI.

This is analogous to the formation of the homologous anilines from
the alkyl anilines (p. 601). They also result from the alkyl piperi-
dines by the splitting-off of hydrogen when heated with concen-
trated sulphuric acid (p. 951). Conversely, nascent hydrogen
(best from metallic sodium and alcohol) converts them into alkyl
piperidines.

Higher alkyl pyridines, with unsaturated side-chains, may be synthesized by
condensing a-methyl pyridines and aldehydes. This can be effected by means of

METHYL-ETHYL PYRIDINE. 943

zinc chloride. Thus, paraldehyde yields a-allyl pyridine, C5NH4.CH:CH.CH3,
benzaldehyde forms Stilbazole, C5NH^.CH:CH.C„H5 (analogous to stilbene),
while ethyl-a-methyl pyridine yields ethyl-a-slilbazole (Berichte, 21, 818, 3099).
a-Methyl pyridine and methylal yield, rather singularly, dipicolylmethane, CH„

An aldol condensation sometimes occurs between a-methyl pyridine and the
aldehydes. Bases with hydroxylated side-chains are then produced; these are
called Alkines and Tropines (Ladenburg, Berichte, 22, 2583 ; 23, 27Q9) : —

C5H4N.CH3 + CH^O = C5HiN.CH2.CH2.OH.

a-Picolyl alkine.

a-Picolyl methyl alkine, C5H4N.CH2.CH(OH).CH3, is similarly obtained with
ethyl aldehyde, etc.

I. Methyl Pyridines, C ^M iJi<Z\i. ^'^ , Picolines.

a- and S-Methyl Pyridine occur in bone oil, and may be separated by means
of their PtCl^ salts [Annalen, 247, 5). The /3-body has been obtained artificially
by different reactions. a-Picoline results when pyridine is methylated. It boils at
130°; its sp. gr. is 0.965 at 0°, and it is oxidized by potassium permanganate to
picolinic acid; the ;3-body boils at 143°, and yields nicotinic acid. The picoline
formed when strychnine is distilled is identical with /3-picoline {Berichte, 23, 3151).
y-Methyl Pyridine, from coal tar, is produced when methyl pyridine iodide is
heated to 290°. It boils at 144°. Its sp. gr. is 0.974 at 0°. It yields isonico-
tinic acid when it is oxidized {Annalen, 247, 11).

Sodium and alcohol convert the three methyl pyridines into methyl piperidines.

^. Dimethylpyridines, C5H3(CH3)2N, Lutidines.

There are six isomerides. Several occur in that fraction of bone-oil boiling at
150-170°. aa-Lutidine occurs in the greatest abundance; associated with it are
ay- and a/3-lutidines {^Berichte, 21, 1006). aa-Lutidine boils at 142°; its specific
gravity is 0.942 at 0°. It yields aa-pyridine carboxylic acid when oxidized
{Annalen, 247, 28). ay-Lutidine, from coal tar, boils at 157°; its sp. gr. is
0.9493 at 0°. It yields ay-pyridine dicarboxylic acid when oxidized. ^;3-Luti-
dine, from the corresponding dimethyl pyridine carboxylic acid, boils at 170°,
and when oxidized becomes dinicotinic acid {Berichte, 23, 1113).

J. Ethyl Pyridines, C^'ii.i{C^'R^)'i^.

a- Ethyl pyridine is prepared, together with the y-, on heating pyridine-ethyl
iodide (to 290°). It boils at 148°; its sp. gr. is 0.949 at 0°, and yields picolinic
acid when oxidized {Annalen, 247, 13). /3-Ethyl pyridine has been obtained
from cinchonine and brucine on heating with caustic potash. It boils at 166°, and
yields nicotinic acid when oxidized. y-Ethyl pyridine, produced together with
the a- and /?-, boils at 165°, and yields isonicotinic acid when oxidized. Its sp. gr.
is 0.952 at 0°. Sodium and alcohol convert all three isomerides into ethyl
piperidines.

4. Trimethyl Pyridines, C5H2(CH3)3N, Collidines.

Sym. (l, 3, S)- coUidine was first obtained by distilling sym. coUidine dicar-
boxylic acid with lime. It is present in coal tar. It boils at 172°, arid turns
brown on exposure to the air. When oxidized it yields pyridine tricarboxylic acid
{Berichte, 20, Ref. 106; Annalen, 21, loil).

(1,4)- Methyl-Ethyl Pyridine, C5H3(CH3l(C2H5)N, has been prepared
from various aldehyde compounds, hence called aldehydine or aldehydcollidine.
It boils at 178°, and when oxidized forms (I, 4)- pyridine dicarboxylic acid

944 ORGANIC CHEMISTRY.

[Annalen, 247, 41). See Annalen, 247, 46, for two additional methyl ethyl
pyridines.

Propyl Pyridines, C^Yi^{C^^^)'H.

a-Propyl Pyridine, Conyrine, is produced on heating conine hydrochloride
with zinc dust, and is obtained on heating inactive a-propyl piperidine (Annalen,
247, 20). It is a bright blue, flourescent oil, boiling at 167°. If oxidized, it
yields picolinic acid. Heated with hydriodic acid it again forms conine.

j3- Propyl Pyridine appears to be a base, formed by distilling nicotine, C,^Hjj
Nj, through an ignited tube. It boils at 170°, and is oxidized to nicotinic acid.

a-Isopropyl Pyridine, C5H4{C3Hj)N, is produced together with the y-com-
pound when pyridine propyl iodide or isopropyl iodide is heated to 290° {Annalen,
247,22). It boils at 158°. When oxidized it forms picolinic acid. Sodium and
alcohol change it to isopropyl piperidine (p. 952). y-Isopropyl pyridine boils at
177°, and yields isonicotinic acid when oxidized (p. 946). See Betichie, 23, 685,
for the dimethyl ethyl pyridine, obtained from propionic aldehyde.

a-Vinyl Pyridine, C5H4(C2H3)N, results when pyridine vapors are con-
ducted together with ethylene through a tube heated to redness, as well as from
a-picolyl alkine by the loss of water, and from pyridine acrylic acid. It is a liquid
with a sweet odor, and boils at 160°. It yields picolinic acid when oxidized
{Berichte, 20, 1644).

a-AUyl Pyridine, C5H4(C3H5)N, is produced when a-picoline and paralde-
hyde are heated to 200° [Annalen, 247, 26). Its odor is like that of conyrine.
It boils at 190°. Sodium and alcohol convert it into a-propyl piperidine (in-
active conine, p. 952).

Phenyl Pyridines, C^n^{C^li^)'i^.

a- and /3-Phenyl pyridine have been obtained from a- and /3naphtho-quino-
line (see these). By the oxidation of the latter we get a- and /3 phenyl-pyridine-

dicarboxylic acids, CgHgNJ ^«,^|^*-''-'2^, and when 2CO2 split off from these

the phenyl pyridines are produced (p. 950).

a- Phenyl pyridine boils at 267°, and when oxidized with chromic acid yields
picolinic acid; /3-phenyl pyridine boils at 270°, and yields nicotinic acid.

7-Phenyl pyridine, formed from aceto-acetic ester, etc. (p. 939), boils at 275°,
and yields isonicotinic acid by oxidation. It consists of colorless needles melting
at 77°. Metallic sodium and alcohol reduce it to y-phenyl piperidine (p. 952).

Pyridyl Alkines (p. 943).

«-Picolyl Alkine, QNH^.CH^.CHj.OH, from a-picoline and formic aldehyde,
is a thick syrup, boiling at 179° under 22 mm. pressure. a-Picolyl methyl-alkine,
C5HjN.CH2.CH(OH).CH3, derived from acetaldehyde, boils at 179° under 18
mm. pressure. For additional pyridyl alkines consult Berichte, 23, 2709, 2725.

Oxy-derivatives of the Pyridines.

These resemble the phenols in deportment, especially the amidophenols. They
are formed by analogous reactions, with special ease from the oxypyridine carboxylic

DIOXYPYRIDINES. 945

acids by the elimination of the carboxyl groups. They form salts with bases and
acids. Ferric chloride imparts a red color to nearly all their solutions. On the
other hand, different oxypiperidines and oxypiperidinic acids manifest the deport-
ment of imides or lactams. They must be viewed as keto or ofz-compounds of
the dihydro-pyridines, and are called Xhtxeioi^ fyridones (lutidones), corresponding
to the formulas : —

=^CH — CO\j,„ p„/CO . CH\ „ (,„/CH = CH\„„

a-Pyridone. |3-Pyridone (?) y-Pyridone.

It is undetermined whether these formulas are isomeric or tautomeric with the
hydroxyl formulas. However, isomeric alky] compounds of both types are known
[Berichte, 22, 73).

1. Oxypyridines, C^^iOYi.')'^ or Pyridones. Three Isomerides. a-Oxypyri-
dine, a-Pyridone (l =5), is obtained from oxyquinolinic acid (p. 948) and from
oxy-nicotinic acid (from coumalic acid, p. 947), by the elimination of carbon
dioxide (^Berichte, 18, 317; ig, 2433). It dissolves readily in water and alcohol,
crystallizes in needles, melting at 106°. Ferric chloride colors it red. Bromine
water converts it into a dibromoxypyridine, C5HjBrj(0H)N, melting at 206°.

j3-Oxypyridine is formed when ;8-pyridine sulphonic acid is fused with caustic
potash. It is very soluble in water and alcohol, crystallizes in needles, melts at
124°, and can be distilled without decomposition. Its ethyl ether, C5H^(O.C2H5)N,
is produced by the action of alcoholic potash upon /3-brompyridine. Hydriodic
acid again decomposes it, at 110°, into fl-oxypyridine {Berichte, 17, 1896; 18,
Ref. 634).

7-Oxypyridine, y-Pyridone, is produced by heating oxypicolinic acid (from
comanic acid, p. 958) and ammon-chelidonic acid. It is very soluble in water,
soluble with difficulty in ether, crystallizes in plates with 1H2O, and when an-
hydrous melts at 148°. Ferric chloride colors it yellow. Methyl iodide converts
it into the hydroiodide of «-methyl pyridone, a crystalline mass, melting at 89°. It
can also be obtained from methyl ammon-chelidonic acid, hence its methyl group
is attached to nitrogen. Hydriodic acid does not even decompose it at 165°.
y-Methoxy-pyridine, C5H^(0.CHg)N, is isomeric with it. This compound may
be prepared by heating chlorpyridine with sodium ethylate. It boils at 190°, reacts
alkaline, and is broken down when heated to 100° with hydriodic acid {Berichte,
18, 930, Ref. 382).

2. Oxylutidines, C5H2(CH3)2(OH)N or Lutidones, C5H20(CH3)2NH.

Pseudo-lutido-styril, CH3.C. ptr.rfcjj^N /NH, (3, ^-Dimethyl-a-pyridone,

is obtained from the ammonium hydrate of collidine dicarboxylic ester, C5(CH3)3N
(C02.C2H5)2 (p. 949), by a complex transposition (Berichte, 17, 2903); and
also from the amido-aceto-acetic ester condensation product (p. 940) {Berichte, 22,
447). It crystallizes in minute needles, that melt at 180° and boil about 305°. It
forms (i, 3)-lutidine when distilled with zinc dust.

(2, 6)-Dimethyly pyridone, Co/^|^^3)-CH\j^j.j^ y-Z«/;(/oK^, results from

lutidone dicarboxylic acid and oxy-lutidine dicarboxylic acid by the elimination
of the carboxyl groups. It crystaUizes with i^ molecules of water; when an-
hydrous it melts at 225° and boils at 350° {Berichte, 20, 156). It forms (2, 4)-
lutidine when distilled with zinc dust.

3. Dioxypyridines, C5H3(OH)2N.

Three isomeric bodies have been obtained from pyridine disulphonic acid,
dibronn-pyridine and dioxypicolinic acid {Berichte, 18, Ref. 633).

79

946 ORGANIC CHEMISTRY.

4- (i. 3. S)-Trioxypyridine, C5H2(OH)3N, or Triketohexahydropyridine,

''*-'\'rH CO/-'^^' ^"''^*°P'P^"'^'°^' ''^^'^^ '''^ ^^""* relation to pyridine that
phloroglucin bears to benzene (p. 695). It can be obtained by boiling glutazine
with hydrochloric acid. It is a microcrystalline yellow product, that swells up at
220-230° and then decomposes. Heated with ammonia it forms Glutazine,
CjHjNj ; which can also be prepared by heating acetone dicarboxylic ester with
ammonia (p. 940) [Berichie, 19, 2708; 20, 2655).

Pyromecazonic Acid, C5Hj(OH)3N, is an isomeric trioxpyridine, obtained
from pyromeconic acid. Ferric chloride colors it a dark indigo blue.

Pyridine Carboxyl Compounds.

The pyridine carboxylic acids are obtained from the homologous
pyridines by oxidizing them with potassium permanganate, and are
also formed by oxidizing the quinolines and alkaloids (with nitric
acid, chromic acid or potassium permanganate). The lower acids
can be prepared from the polycarboxylic acids, e.g., C5(CH3)3N
(C02H)2 and C5N(CO.iH)5, by the partial elimination of single car-
boxyls, and by completely removing the latter (by heating with
lime) all the acids yield pyridine or its homologues. As these acids
represent combinations of carboxyl with the basic pyridine radical,
they therein manifest a deportment analogous to that of the amido-
acids, and are also capable of forming salts with acids. The basic
character of these acids diminishes with the increase in number of
carboxyls, and disappears entirely in the penta-carboxylic acid.
Those pyridine- (and quinoline) carboxylic acids, containing a car-
boxyl in the a-position, are colored red by ferrous sulphate.

I. Pyridine-mono-carboxylic Acids, CgHjNOj = C5H^N(C02H).

re-Pyridine-carboxylic Acid (l or orlho), Picolinic Acid, was first obtained
by the oxidation of a-picoline. It is very readily soluble in alcohol and water,
crystallizes in white needles, which melt at 135-136°, and sublime. Ferrous
sulphate imparts a faint yellow color to their solutions. By the action of sodium
amalgam, ammonia is split off, and the acid, CgHjO,, formed; this melts at 85°-

/3-Pyridine Carboxylic Acid (2 or meta), Nicotinic Acid, was first obtained
by oxidizing nicotine. It is also prepared from /3methyl and ethyl pyridine, from
^-cyanpyridine and from the three pyridine dicarboxylic acids (quinolinic, cincho-
meronic and isocinchomeronic acids) by the elimination of a COj-group. The
easiest course to pursue in preparing the acid consists in heating quinolinic acid
with hydrochloric acid to 180°. It crystallizes from hot water in needles or warty
masses, and melts at 228-229°.

y-Pyridine-carboxylic Acid (3 or para), Isonicotinic Acid, is obtained by
oxidizing y-methyl- and ethyl-pyridine, and from the dicarboxylic acids, cincho-
meronic andr^lutidinic acids, by the splitting-ofif of COj. It is almost insoluble in
hot alcohol, forms fine needles when crystallized from hot water, and sublimes in
small plates without previous melting. When heated in a closed tube it melts at
304°.

yuiuiULiNic ACID. 947

Pyridine Fatty Acids.

The known acids of this group are a-pyridyl acrylic acid and a-pyridyl lactic
acid, which appear to be closely related to anhydroecgonine and ecgonine — deriva-
tives of cocaine {Berichte, 23, 224).

a-Pyridyl Acrylic Acid, CgHjN.CHiCH.COjH, is formed together with
a-pyridyl lactic acid from the condensation product of a-picoline and chloral by
the action of caustic potash. It crystallizes in minute needles, melting at 202°.
a-Pyridyl LacHc Acid, C5H4N.CHj.CH(OH).C02H, consists of iine needles,
melting at 146°.

Oxypyridine Monocarboxylic Acids.

)'-Ox3rpicolinic Acid, C5H3(OH)N(C02H) (7a), has been obtained, in a syn-
thetic manner, from comanic acid, (p. 958), on digesting with ammonia. It
crystallizes in shining leaflets, containing one molecule of water. It melts at 250°,
and decomposes into CO, and 7-pyridone (p. 945).

a'-Oxynicotinic Acid, C5H3(OH)N(C02H) (a'|9) or a-Pyridone-^' -c?x\m^j\\Q.
acid, C5H30(NH)C02H (p. 945), is produced when ammonia acts upon coumalic
acid ester (Berichte, 17, 2390) ; also when oxyquinolinic acid (p. 948) is heated
to 200°. It dissolves with difficulty in water and alcohol, crystallizes in delicate
needles, and melts at 303°, breaking down at the same time into CO, and a-pyri-
done. Sodium amalgam eliminates its nitrogen as ammonia. Methyl-oxy nicotinic
acid is obtained from it by the action of methyl iodide and caustic potash. This
acid can also be derived from coumalic acid by means of methylamine. Sodium
amalgam will cause it to split off methylamine. Therefore, its methyl group is
attached to nitrogen, and the acid is an a-methylpyridon carboxylic acid, CjHjO-
(N.CH3).C02H {Berichte, 18, 318).

Dioxypicolinic Acid, C5H2(OH)5N(C02H), Comenamic Acid,is derived from
comenic acid (p. 959) by aid of ammonia. It crystallizes in plates, containing two
molecules of water. Ferric chloride imparts a purple-red color to its solution.
Oxalimide (p. 407) is obtained from it by the action of nitrous acid in glacial
acetic acid yBerichle, ig, 3228).

Dioxyisonicotinic Acid, C5H2(OH)2N(C02H), Citrazinic Acid, is formed
when citramide is heated with hydrochloric or sulphuric acid. It is a bright
yellow insoluble powder, which decomposes without melting on being heated
beyond 300°. Its alkaline solution acquires a deep blue color on exposure to the
air. It yields y-pyridine carboxylic acid by the reduction of its hydroxyl groups.
See Berichte, 23, 831, as to its constitution.

Methyl Pyridine Monocarboxylic Acids.

ay-Picoline Carboxylic Acid, C5H3(CH3)N(C02H)(CH3 in 7), is obtained on
heating uvitonic acid (p. 949) to 280°. It suWimes without previously fusing, and
when oxidized becomes lutidinic acid (p. 948).

^7-Methyl-Pyridine.Carboxylic Acid (CH3 in y) results on heating methyl
quinolinic acid to 170°, or when it is boiled with glacial acetic acid. It melts at
209-210°, and is oxidized to cinchomeronic acid.

Lutidine Carboxylic Acid, C5H2(CH3)2N(C02H)(a/37-C02H in /3). Its
ethyl ester results in the condensation of aceto-acetic ester with aldehyde and
aldehyde-ammonia (p. 939). The free acid contains two molecules of water of
crystallization, yields 07-lutidine by the elimination of carbon dioxide, and when
oxidized forms a/37-pyridine tricarboxylic acid (p. 949).

2. Pyridine Dicarboxylic Acids, CjHjNOj ^ C5H3N(C02H)2.
The six possible isomerides (p. 941) are known {Berichte, 19, 293).
I. Quinolinic Acid {n/3 or I, 2) is obtained from quinoline and from i and 4
methyl-quinoline by oxidation with potassium permanganate {Berichte, ig, 31).

948 ORGANIC CHEMISTRY.

It is sparingly soluble in water and alcohol, crystallizes in shining, short prisms,
melts at igo°,' and decomposes (by slowly heating to i6o°) into COj and nicotinic
acid {Berichte, ig, 2767). Ferrous sulphate imparts a reddish-yellow color to its
solution. Its anhydride is produced when it is heated with acetic anhydride.
This melts at 134°. Its derivatives are similar to those formed by phthalic
anhydride (Berichte, 20, 1209).

2. Cinchomeronic Acid [fiy or 2, 3) is obtained from quinine, cinchonine and
cinchonidine, by oxidation with nitric acid and by the oxidation of /3)'-methyl-
pyridine carboxylic acid with potassium permanganate. It also results from
pyridine tricarboxylic acid and from apophyllenic acid. It crystallizes from water
in prisms containing hydrochloric acid, and melts at 266°, with decomposition into
Cbj, y-pyridine carboxylic acid and a little nicotinic acid. When heated with
acetic anhydride it yields its anhydride, C5H3N(CO)20, melting at 67°. Sodium
amalgam decomposes it into NH3 and cinchonic acid, C,Hg05, which breaks up
into COj, and dimethylfumaric anhydride (p. 430) on application of heat
[Berichte, 18, 2968).

Cotarnine, CijHiaNOg, boiled with nitric acid, yields Apophyllenic Acid,
CgHjNO^ [Berichte, ig, Ref 706). This is methylated cinchomeronic acid, in
which the methyl group is attached to the nitrogen atom, and has the formula,

C5H3(C02H)N(CH3)^ T (comp. betaine, p. 316). It melts with decomposition

at 242°, and when heated to 250° with hydrochloric acid decomposes into methyl
chloride and cinchomeronic acid.

3. Lutidinic Acid (ay or 1,3) is produced together with isocinchomeronic
acid by oxidizing ay-lutidine and picoline carboxylic acid with potassium perman-
ganate [Annalen, 247, 37). It crystallizes with a molecule of water in micro-
scopic needles, receives a blood-red color from ferrous sulphate, melts at 235°,
and breaks up into COj and y-pyridine carboxylic acid.

4. Isocinchomeronic Acid (a/J' ^ i, 4) is obtained from pyridine tricar-
boxylic acid (Berichte, ig, 131 1) and aldehyde colUdine. It crystallizes from
acidulated hot water, with one or one and a half molecules of water, in microscopic
leaflets, which melt at 236°, and when heated to 220° together with glacial acetic
acid decomposes into CO2 and nicotinic acid. Ferrous sulphate imparts a reddish-
yellow color to'the solution.

5. Dipicolinic Acid [aa' = 1,5) results when aa'-lutidine (p. 943) is oxidized
with potassium permanganate [Annalen, 247, 33). It crystallizes in shining
leaflets, melts at 225°, and at 227° decomposes into two molecules of carbon di-
oxide and pyridine (together with a slight amount of picolinic acid).

6. Dinicotinic Acid (/3/3' := 2, 4) may be prepared from symmetrical pyridine
tetracarboxylic acid, from (i, 2, 4)-pyridine tricarboxylic acid on boiling with
glacial acetic acid [Berichte, ig, 286), and from /3/3-lutidine. (p. 943). It dis-
solves with difficulty in water, consists of minute crystals, melts at 314°, and breaks
down into carbon dioxide and nicotinic acid [Berichte, 23, 11 14).

Oxypyridine Dicarboxylic Acids, C5H2(OH)N(C02H)j.

a-Oxyquinolinic Acid (i, 2, 5 — OH in 5), obtained by fusing quinolinic acid
with KOH [Berichte, 16,2158), also from amidocarbostyril by oxidation with per-
manganate [Berichte, ig, 2432), consists of thick crystals, which char at 254°, but
do not melt. When heated to 195° with water it decomposes into caibon dioxide
and oxypyridine carboxylic acid (see above) ; the silver salt yields o-oxy-pyridine
when heated. Ferric chloride colors it a deep red.

Ammon-chelidonic Acid (i, 5, 3 — OH in 3), chelidamic acid, formed from
chelidonic acid with ammonia, is a white, rather insoluble powder that breaks down
into carbon dioxide and y-pyridone when heated above 230°.

PYRIDINE TRICARBOXYLIC ACID. 949

Methyl Ammon-chelidonic Acid, C5HjO(N.CH3)(C02H)2, obtained by the
aid of methylamine, yields «-methyl pyridone by decomposition (p. 945).

Picoline Dicarboxylic Acids, C5H2(CH3)N(C02H)2.

1. Methyl-quinolinic Acid (i, 2, 3 — CH3 in 3) is produced upon oxidizing
j'-raethylquinoline with potassium permanganate, as an intermediate product to
the tricarboxylic acid. It crystallizes from water in plates or prisms, is colored
yellow by ferrous sulphate, melts about 186° with decomposition, and yields (even
on boiling with glacial acetic acid) carbon dioxide and /3y-methylpyridine car-
boxylic acid (p. 947).

2. Uvitonic Acid is formed when ammonia acts upon pyrcracemic acid, con-
sists of microscopic leaflets, is colored violet-red by ferrous sulphate, melts at 244°,
and above 280° decomposes into COj and picoHne-carboxylic acid. ■*

(i, 3, s)-TrimethyI-(2, 4)-pyridine Dicarboxylic Acid, C5(CH3)3N(COjH)2,
Collidine dicarboxylic acid. The diethyl ester is prepared by tihe oxidation of di-
hydro-collidine dicarboxylic ester (from aceto-acetic ester with aldehyde ammonia,
(P' 939) in alcholic solution with nitrous acid. The free acid, obtained by saponi-
fying the ester, crystallizes in little needles, and decomposes when strongly heated
without melting. Dislilled with lime it yields a (l, 3, 5)-trimethyl pyridine (p.
943)- By successively oxidizing its methyl groups with potassium permanganate
we obtain: lutidine tricarboxylic acid, C5(CH3)2N(C02H)3,picoline-tetra-
carboxylic acid, C5(CH3)N(C02H)^, and pyridine pentacarboxylic acid,
C5N(C02H)5. The separation of but one carboxyl from coUidine-dicarboxylic
acid yields collidine-monocarboxylic acid, C5H(CH3)3N(C02H) (Annalen,
225. 133). which by successive oxidation forms lutidine-dicarboxylic acid,
(C5H(CH3)2N(C02H)2, picoline-tricarboxylic acid, C5H(CH3)N(C02H)3,
and pyridine-tetracarboxylic acid, C5HN(C02H)^.

(3) Pyridine Tricarboxylic Acids, CgHsNOg = C5H2N(C02H)3.

1. a/?7-Pyridine Tricarboxylic acid (i, 2, 3) (tricarbopyridinic acid, carbo-
cinchomeronic acid), is obtained by completely oxidizing quinine, cinchonine,
quinidine and cinchonidine, with potassium permanganate, and by the same treat-
ment of j-methyl quinoline, methyl-quinolinic acid (see above) and cinchoninic acid
(p. 972). It is very soluble in hot water, crystallizes in plates with i^ molecules
of HjO, becomes anhydrous at 115-120°, chars and melts when rapidly heated at
249-250°, with decomposition. At 180° it gradually breaks up (more readily on
boiling with glacial acetic acid) into carbon dioxide and cinchomeronic acid.
Ferrous sulphate gives it a faint red color. It is very probably identical with Ber-
beronic Acid, formed from the alkaloid berberine by oxidation.

2. a;3/3'- Pyridine Tricarboxylic Acid (l, 2,4) is obtained from /3-ethyl quin-
oline and /3-quinoline-carboxylic acid by oxidation with MnO^K. It is colored
reddish-yellow,by ferrous sulphate, and softens with liberation of CO2, about 145°
(p. 948). It IS very soluble in water and forms needles on crystallizing.

3. Symmetrical aay- Pyridine Tricarboxylic Acid (l, 3, 5) is obtained upon
oxidizing symmetrical collidine (p. 943) and uvitonic acid (see above) with potas-
sium permanganate. It crystallizes with two molecules of water. In an anhy-
drous state it melts at 227°, with decomposition into carbon dioxide and isonico-
tinic acid (Annalen, 228, 29). OMp-Pyridine Dicarboxylic Acid (l, 2, 5) results
when the corresponding lutidine carboxylic acid is oxidized with potassium per-
manganate. It crystallizes in leaflets containing two molecules of water. It melts
at 100° in its water of crystallization, and at 130° breaks down into carbon dioxide
and isocinchomeronic acid (Berichte, 19, 1309).

950 ORGANIC CHEMISTRY.

4. Pyridine Tetra-Carboxylic Acids, CgHjNOg = C5HN(C02H)^.

The (m^y-Acid is produced in the oxidation of collidine carboxylic acid and
flavenol (p. 971). It forms needles, containing two molecules of water. It loses
water very slowly above 115°, and when anhydrous melts at 227°. Ferric chlor-
ide colors it cherry-red {Berichte, 17, 2927). Symmetrical aa^^-acid is derived
from the corresponding lutidine dicarboxylic acid (from aceto-acetic ester and iso-
butylaldehyde etc.) by oxidation. It consists of minute needles, containing one
molecule of water, and at 150° breaks down into carbon dioxide and dinicotinic
acid. Ferrous sulphate imparts a blood-red coloration to its solution {Berichte,
19, 284).

5. Pyridine Pentacarboxylic Acid, C5N(COjH)5 = CnjHjNOi,,, is
formed by the oxidation of synthetic collidine dicarboxylic acid and from the acids
obtained in its oxidation. It crystallizes in microscopic needles, containing two
molecules of vfater. It dissolves very readily in water, blackens at 200°, and de-
composes, without melting, at 220°. Ferrous chloride imparts to its solutions a
dark red color.

C5H3N.CO2H
Phenylpyridine Dicarboxylic Acids, . . There are two iso-

CeH^.CO^H
meric acids, u,- and /?-, which have been prepared by oxidizing a- and /J-naphtho-
quinoline (p. 974) with potassium permanganate. They yield u- and /-phenyl-
pyridine by the loss of two molecules of carbon dioxide.

C5H3.N.CO2H
Dipyridyl-dicarbonic Acids, . . Two isomeric acids, a- and

CjHa.N.CO.H
j8-, have been formed by oxidizing the two phenanthrolines with potassium per-
manganate. Two dipyridyls are formed by the loss of two molecules of carbon
dioxide (p. 942).

Hydropyridine Derivatives.

The pyridines yield hydrogen additive products, similar to those produced by
benzene. They form when tin and hydrochloric acid act upon the pyridines, or
more readily by the action of sodium upon the alcoholic solution ; the hexa-hydro-
derivatives are then the direct products. Even oxypyridines are reduced by so-
dium and alcohol to hexa-hydro pyridines [Berichte, 20, 250). Several natural
alkaloids belong to this class of hydropyridines ; they are especially interesting.

Hexahydro-pyridine, QH^N = CH2('^^''^g''')NH, Pi-

peridine, occurs attached to piperic acid as piperine (see below) in
pepper. It may be artificially prepared by reducing pyridine, also
by distilling the hydrochloride of pentamethylene diamine (p. 313),
or by the action of sodium upon an alcoholic solution of trimethy-
lene cyanide (p. 311).

Piperidine is a liquid that dissolves quite easily in water and alcohol. Its odor
is like that of pepper. It boils at 106°. It shows a strong alkaline reaction. lis
salts with the acids crystallize well. When piperidine is heated to 300° with sul-

METHYL-PIPERIDINE. 95 1

phuric acid, or to 260° with nitrobenzene, or upon boiling it with silver oxide, it
loses six hydrogen atoms and changes to piperidine. Nitrous acid converts it
into the ni/roso compound, CjHjjiN.NO, boiling at 218°.

Piperidine is very reactive with brom- and iodo-benzenes, forming «-phenyl-
piperidines with them [Berichie, 21, 1921). This power of combination is mate
rially diminished with a methyl piperidine {Berichle, 23, 1388).

Potassium permanganate oxidizes piperidine to d-amidovaleric and 7-amidobuty-
ric acids. The homologous piperidines are analogously oxidized {Berichte, 21, 2237 ;

22, 1035). (i-Amidovaleric acid loses water and yields oxypiperidine ox piperi-
done, CjHgON (p. 945), a crystalline base, melting at 40° and boiling at 256°.
It is a violent poison, resembling strychnine. The acid itself is not poisonous.
Pyrrolidon, from y-amido-butyric acid, is also a strychnine-like poison (Berichte,

23, 2772).

Dipiperidyls, C^HjjN.CjHiuN, are produced upon reducing the dipyridyls,
(C5H^N)2, with sodium and absolute alcohol (^Berichte, 21, 2929). The same
may be done with hexahydro-dipyridyls (p. 9S3).

Piperidine is an imide base. It contains the NH-group and can form alkyl and
acid derivatives. The alkyl compounds (the hydroiodides) result by the union of
piperidine with alkyl iodides.

»-Methylpiperidine, CjHjdN.CHj, and n-Etkyl Piperidine, CjHjjN.CjHj,
are alkaline liquids, boiling at 107° and 128° respectively. With methyl iodide
methyl piperidine forms dimethyl piperidine ammonium iodide, CjHjjNiCHjjjI.
Potassium hydroxide, upon distillation with the latter, causes the decomposition of
its ring structure and yields Dimethyl piperidine, Q^^[Ciii^^ = CHjiCH.CHj.
CH2.CH2.N(CH,)2. This is a base, boiling at 118°. It reunites with methyl
iodide to the ammonium iodide, C5Hg.N(CH3)3l ; silver oxide converts this into
the hydroxide, C5Hg.N(CH3)3.0H, which on the application of heat breaks down
into trimethylamine and Piperylene, C^Hg = CH2:CH.CH2.CH;CH2 (boiling at
42°). This is the method pursued by Hofmann in buildmg up the piperidine
bases {^Berichte, 16, 2058; ig, 2628).

«- Phenyl Piperidine, CjHjjiN.CgHj, from piperidine and brombenzene, is
a liquid boiling about 250° (^Berichte, 21, 2279, 2287).

«-Acetyl Piperidine, CjHuN.C^HgO, from piperidine by means of acetyl
chloride, boils at 226°. Benzoyl Piperidine, CjHj^N.CO C5H5, is a solid.
Piperidine urethanes, C5Hj5N.CO.OR, result from the action of chlorcarbonic
ester. When these acid derivatives are oxidized the piperidine nucleus is torn
asunder; saturated amido acids result (.5^nV^/^, 17, 2544; 19, 500)-

Piperine, Ci^HjjNOg = CjHjoN.CijHjOj, the alkaloid, is an acid derivative
of piperidine with piperic acid (p. 822). It occurs in different varieties of pepper
{e.g., Papaver niger). It is artificially produced by the action of piperic acid chlo-
ride upon piperidine. It crystallizes in prisms and melts at 128°- It dissolves
with a deep-red color-in sulphuric acid. It is a very feeble base, and is decom-
posed by boiling alcohol into piperidine and piperic acid.

Sodium and alcohol reduce the homologous pyridines to homologous piperidines.
They are known as Pipecolines, C5H9(CH3)NH, lupetidines, 05113(0113)2
NH, etc. (Ladenburg, Berichte, 18, 920).

a-Methyl Piperidine, C5H9(CH3)(NH), o-Hydropicoline, boils at 118°.

;3-Methyl Piperidine, /3-Hydropicoline, boils at 126°. o-Ethyl Piperidine,
05Hg(C2H5)NH, boils at 143°.

952 ORGANIC CHEMISTRY.

a-Propyl Piperidine, C5H9(C3H,)NH = CsHi,N, has been ob-
tained by the action of sodium and alcohol upon a-allyl pyridine
(p. 944). It boils at 167°. In properties and action it is very
similar to conine. Its optical inactivity alone distinguishes it from
the latter. By careful crystallization of its tartrate (induced by a
small crystal of conine tartrate) it may be resolved (like inactive
racemic acid, p. 478) into two optically active modifications, one
of which is tevo-rotatory and the other dextro-rotatory. The latter
is identical with conine — the first synthesis of an active alkaloid
(Lsidenhmg, £erickte, 19, 2584; 22, 1405).

Conine, QHi,N, dextro-rotatory a-normal propyl piperidine,
C5H9(C3H,)NH, occurs in hemlock (Conium maculatum), chiefly
in the seeds, and is obtained by extraction with acetic acid or
distillation with soda. It is a colorless liquid, having the odor of
hemlock, and boiling at 167-168°; its sp. gr. is 0.886 at 0°. It
deviates the plane of polarization to the right (a„= 13-8°). Its
hydrochloride melts at 217°.

As secondary amine it yields alkyl and acid derivatives. If its nitrosamine,
CgHi5N(N0) (azoconydrine), be digested with PjOj it forms Conylene, CgHjj,
boiling at 125°. Benzoyl Conine, CgHj5N.CO.CgH5, is oxidized by permanga-
nate of potassium to homo-coninic acid and amidovaleric acid. This nucleus is
ruptured in the reaction [Berichte, 19, 506). Dimethyl conine iodide, CgHjgN
(CHg).CH3l, obtained from methyl conine and methyl-iodide, manifests the same
deportment as the piperidine derivative (see above), and finally decomposes into
trimethylamine and conylene, CgH^.

Conydrine, CgHj^NO, is an oxyconine and is intimately related to conine,
occurring with the latter in hemlock and in the distillation it passes over last. It
crystallizes in leaflets at 120°, distils at 226°, and sublimes about 100°. It reverts
to conine when heated with hydriodic acid (Berichte, 18, 130).

a-Isopropyl Piperidine, C5Hg(C3H,)NH, is derived from a-isopropyl pyri-
dine by the action of sodium and alcohol. It is very similar to conine and boils
at 160°.

7-Phenyl Piperidine, C5Hg(CgH5)NH, from y-phenyl piperidine, boils about
256° {^Berichte, 20, 2590).

See Berichte, 23, Ref. 645 for the benzylpiperidines.

Tetrahydropyridines, C5H5(H^)N, Piperidelnes.

fl-Methyl Piperidelne, C5H8(CH3)N, and a-Ethyl Piperideine, C5H8(Cj
H5)N, have been prepared by the action of bromine and sodium hydrate upon
methyl and ethyl piperidine {Berichte, 20, 1645).

A dipiperideine, Ci|,HjgN2, has been similarly derived from piperidine
(Berichte, 22, 1322, 1377).

a-Propyl Piperideine, C5H8(C3H,)N. The three isomeric bodies a-, /?-,
7-coniceSns, have been obtained from conydrine, CgH^NO (see above), by heating
it with PjOj or to 220° with hydrochloric acid, and also by the action of bromine
and sodium hydrate upon conine. They are again reduced to conine when
heated with hydriodic acid {Berichte, 23, 680 and 2141).

DIAZINES, OR AZINES. 953

Paraconine, CjHjsN, is a propyl tetrahydropyridine. It is formed from nor-
mal butyraldehyde and butylidene chloride upon heating them with alcoholic
ammonia. It is a colorless liquid, with stupefying odor. It boils at 168-170°
(Berichte, 14, 2105).

Tropine and tropidine are also tetrahydropyridine derivatives.

Tropine, CaHijNO, obtained by the decomposition of the
alkaloid atropine, crystallizes from ether in plates, melts at 63°,
and boils at 229° When heated with concentrated hydrochloric
acid or with glacial acetic acid to 180°, water separates, and it
yields tropidine, CsHisN, which can also be produced by heating
anhydroecgonine with hydrochloric acid to 280° {Berichte T.'^, 1389).
It is an oil with an odor like conine. It boils at 162°. Hydro-
bromic acid, acting upon it in the cold, causes it to revert to tropine.
{Berichte 23, 1780, 2225).

Tropine is an n-methyl-a-oxy-ethyl-tetrahydropyridine and belongs to the alkines
(p. 315), while tropidine is an K-Methyl-a-vinyl-tetrahydropyridine (Ladenburg,
Berichte 20, 1648; 23, 2587) : —

C5H,N(CH3).CHj.CH,.OH ' and C5H,N(CH3).CH : CHj.
Tropins. Tropidine.

Tropidine forms hydrotropidine, CjHjsN, by reduction ; the distillation of its
hydrochloride yields methyl chloride and Norhydrotropine, CjHjjN. The
latter compound is isomeric with a-ethyl piperidine (see above) and when distilled
with zinc yields a ethyl pyridine, C^H^N.CjIIj. Anhydroecgonine, CsHjN
(CH3).CH : CH.COjH, is a carboxyl derivative of tropidine ; by the loss of car-
bon dioxide it forms tropidine.

Triacetonine is closely related to tropidine (p. 209).

Nicotine, CioHuN^ = C5H4N. CsHjoN, is a hexahydrodipyridyl.
It is found in the leaves of the tobacco plant, and may be obtained
by distilling the residue from the aqueous extract with lime. It is
an oil, readily soluble in water and alcohol. Its odor is very pene-
trating. It becomes brown in color on exposure to the air. Its
specific gravity at 15° is i.oii. It boils at 241°- It is a powerful
diacid base and is poisonous. Chromic acid or potassium perman-
ganate oxidizes it to nicotinic acid. Sodium, acting upon its alco-
holic solution, converts it into dipiperidyl, CioH^oNj (p. 951).

Nicotidine and Isonicotine, C^HuNj, are isomeric with nicotine. They
result from the reduction oip- and »2-dipyridyl (p. 942) (Berichte, 16, 2521).

DIAZINES, OR AZINES.

These compounds bear the same relation to pyridine, that the " five-membered "

diazoles or azoles bear to pyrrol (p. S51). They contain a " six-membered " ring,

consisting of four C-atoms and two N-atoms — CjH^Nj. They may be considered

pyridine derivatives, in which a CH-group has been replaced by nitrogen. There

80

954

ORGANIC CHEMISTRY.

are three isomeric diaziue nuclei — the orthodiazines, meiadiazines and paradia-
zmes, corresponding to the relative position of the two N-atoms. The usual desig-
nations are pyridazine, pyrimidine and pyrazine* : —

H

N C N

/ V / \ / %

HC CH N N N CH

II I II II I

HC CH HC CH HC CH

\ ^ \ / \^^

N C C

H H

Paradiazine Metadiazine Orthodiazine

Pyrazine. Pyrimidine. Pyridazine.

I. Paradiazine or Pyrazine Compounds.

These contain the two nitrogen atoms in the para position. They were formerly
called ketines or aldines {Berichte, 19, 2524; 20, 431; 21, 20). They are pro-
duced by the following methods : —

1. By reducing the isonitroso ketones and isonitroso acetoacetic esters with tin
and hydrochloric acid. The amido-ketone compounds formed at first sustain an
immediate condensation. Thus, isonitroso acetone (p. 206) yields dimethylpyra-
zine (ketiue) {Berichte, 15, 1059) : —

2CH3.C0.CH{N.0H) + 6H = CJl2(CH3)2N2 -f 4H2O,
CHj.CO.CHj.NH. CH3.C — CH = N -f 2H2O + H^.

= II I

-fNH2.CH2.CO.CH3 N — CH = C.CH3

Dimethyl Pyrazine.

Again, isonitrosomethyl acetone, CH3.CO.C(N.OH).CH3 (p. 209) yields tetra-
methyl pyrazine, C4(CH3)4N2 (dimethyl ketine), and isonitrosomethyl propyl
ketone, CH 3. CO.C(N.OH).C2H5, gives rise to dimethyl ethyl pyrazine, C4(CH3)2
(C2H5)2N2 (diethyl ketine) [Berichte, 14, 1463). Dimethyl pyrazine dicarboxylic
ester, C4(CH3)2N2(C02)R2> was similarly prepared from isonitroso acetoacetic
ester (Berichte, 15, 1051).

Tetraphenylpyrazine is obtained from benziloxime (p. 888). Isonitrosoaceto-
phenone, C8H5.CO.CH(N.OH) (p. 728) may be condensed to isoamidoaceto-
phenone, CgHj.CO.CHj.NH^, which ammonia will convert into diphenyl pyrazine
(isoindol) {Berichte, 21, 1278, 1947; 22, 562).

2. By the action of ammonia upon brom- keto-derivatives, R.CO.CBr.HR. Thus,
brom (chlor) acetophenone, CjHj.CO.CHjBr, yields diphenylpyrazine, C4H2(C8
H5)2N2, and brom- or oxy-l^vulinic acid, CHjCO.CHBr.CH^.COjH (p. 344)
yields tetramethyl pyrazine with the simultaneous liberation of carbon dioxide.
With aniline, on the other hand, the a-brom ketones form indol derivatives
(p. 828) {Berichte, 21, 123).

Pyrazines or paradiazines are diacid bases with a narcotic odor (resembling car-
bylamine). They are mostly liquids and volatilize quite readily with steam.

Free Pyrazine, C^H^Nj, appears to be produced when ammonia acts upon
chloracetal, CH2Cl.CH(OR)2 {Berichte 21, 1481).

*Widmann uses the texms piazine,miazine, oiazine {Jour. pr. Chem.,zi, 185).
Compare Knorr, Berichte, 22, 2083; Hantzsch, Annalen, 249, 1.

METADIAZINES OR PYRIMIDINE DERIVATIVES. 955

Dimethyl Pyrazine, C4H2(CH3)jN2, Ketine, from isonitrosoacetone (see
above) boils with decomposition about 170-180°. Tetramethyl Pyrazine, C4
(CH3)4N2, Dimethyl Ketine, from isonitrosomethyl acetone and from Isevulinic
acid, crystallizes with three molecules of water in brilliant needles. When an-
hydrous it melts at 86° and boils at 190°. Diphenyl Pyrazine, C ^Ji ^i*^ e^ 5)1
N2, from bromacetophenone and amidoacetophenone,was formerly called isoindol
{Berichie 21,1279). It forms shining needles or leaflets and melts at 195°-

Dimethyl pyrazine DicarboxylicAcid,C4(CH3)2N2(C02H) 2, from isonitroso-
aceto- acetic ester (see above) (ketine di-carboxylic acid), is produced by oxidizing,
dimethyl ethyl pyrazine with potassium permanganate {^Berichie 20, 2524). It
melts about 195° and decomposes into carbon dioxide and dimethyl pyrazine (?).

Hydropyrazines. Piperazines.

Diethylene diamine, described p. 313, may be claimed as a hexahydropyra-
zinc, C^HijN, ^ HN^p j,2'_„2>NH. It sustains the same relation to pyrazine,

that piperidine bears to pyridine, hence it is called Piferaaine. Formerly it was
described as a liquid boiling at 170° [Berichte^ 23, 326). According to A. W.
Hofmann it is a crystalline solie^^elting at 104°, and boiling at 145-146°. Ben-
zoyl chloride converts it into the (/iiJ^wzoy/ derivative, melting at 191° {^Berichte,
23, 3297). It is identical with eihylenimine (C2HjNH)2, which was first obtained
as a carbonate, a porcelanous mass, melting at 159-163° [^Berichte, 21, 75^!
23, 3303, 3718). Spermine on the contrary seems to have the simple formula
C2H5.N.

«-Diphenyl Piperazine, CjHs.N/^ j, jt'^Ptt^ ^N.CgHj, is a diethylene diphenyl

diamine or diethylene aniline, resulting from the interaction of ethylene bromide
and aniline [Berichte, 22, 1387, 177S; 23, I977). It melts at 163°.

Dihydropyrazine, C^HgNj, derivatives are produced by the condensation of
ethylene diamine with ortho diketones, just as the analogous quinoxalines and
phenazines are obtained from the ortho phenylene diarnines (p. 593). For exam-
ple, benzil yiiiis Diphenyldihydropyraaine {Berichte, 20, 267): —

CH,.NH„ CO.C.H5 CHj.NiC.QHs
I +1 =1 I +2H2O.

CH2.NH2 CO.CeHj CHj.NrCCjHj

A series of compounds which have been described as keto- or azi-piperazines
are mainly amid-anhydrides of amido-acids or glycocoUs (p. 368). Thus, glycine
anhydride may be termed a diketo-piperazine ; —

(HN.CH2.CO)2 = Hn/^^^'^hJ/N^-
Glycine Anhydride. Diketopiperazine.

Phenylglycin- anhydride (CsH^.N.CHj.CO) is

K-Diphenyldiketopiperazine, CeHj.N/'^Q-'^^^NH.CoHs, etc. For dif-
ferent groups of similar derivatives see Abenius, Berichte, 21, 1664; 23, Ref. 244,
and Bischof, Berichte, 22, 1810 and 23, 2005-2055; Berichte, 23, 1972.

2. Metadiazines or Pyrimidine Derivatives.

These contain the two nitrogen atoms of the six-membered nucleus in the meta-

position (p. 954). Thus far only amido- and oxy-derivatives have been prepared.

i. Amido-pyrimidines are the so-called f^a«-a/i«««, formed by the polymeri-

956 ORGANIC CHEMISTRY.

zation of the cyan-alkyls (nitriles) when heated to 150° with metallic sodium.
Thus, cyanmethane, CHjCN, yields cyanmethine, CjHgN,, cyan-ethane,
C2H5CN, cyanethine, C^Hj 5N3, and cyan-propane, C3H,.CN, yields cyan propine,
CijlijiN,, etc.

The constitution of the cyan-alkines was made evident by the fact that the
oxy-base obtained by the action of nitrous acid upon cyanmethine is identical with
dimethyl-oxypyrimidine (E. v. Meyer, Jr. pr. Chem., 39, 265 ; Berichte, 22, Ref.
328) :-

CH, /C^s

CH3.C/ \CH yields CH3.C/ ^CH .

N — C N — C^

NH, OH

Cyan-methine. Oxy-dimethyl-pyrimidine.

Amido-dimethyl-
Pyrimidine.

The so-called cyan-ethine (see above) is amidodiethyl-methyl-pyrimidine,

C,H = .C/S^^5??55)^C.CH,. A confirmation of this formula is afforded by

the synthesis of acetyl cyan-ethine from acetamidioe, CH3.C(NH).NH2, on boiling
the latter with acetic anhydride {Berichte, 22, 1600). Analogous cyan alkines are
produced by the action of sodium upon a mixture of two alkylcyanides. The
course of the reaction remains unexplained ; it may be that dicyanalkyls are pro-
duced at first, and these then further combine with a cyanalkyl to form cyan-
alkines {Berichte, 22, Ref. 327). The sodium alcoholates react in the same
manner as metallic sodium {Berichte, 23, Ref. 630).

The cyanalkines, or amido-pyrimidines, are crystalline and strongly, alkaline
bases. They form salts with one equivalent of the acids. They are converted
into oxypyrimidines by the action of nitrous acid upon heating them with hydro-
chloric acid to 200°.

Cyanmethine, C5H5N3, melts at 180°. Cyanethine, C9Hj5N3 = CgH,3N2.-
NHj, crystallizes in white leaflets, melts at 189°, and boils with partial decomposition
at 280°. The oxy-base, CgHjjNj.OH, melting at 156°, forms the chloride,
CjHjjNjCl, by the action of PCI5. Nascent hydrogen converts the latter into
cyanconine, CgHj^Nj, very similar to Conine. It is really methyl diethyl-
pyrimidine {Berichte, 22, Ref. 328).

Cyan methine-ethine, CgHjjNj, resulting from the action of sodium upon a
mixture of cyanmethane and cyanethane, consists of shining leaflets, that melt at
165°, and begin to sublime about 100°. The character of the side-chains in this
compound has not yet been established. (Jour. prk. Ch., 39, 267.)

(2) The oxymetadiazines or oxypyrimidines are formed when the amidines
of the paraffin and benzene series act upon acetoacetic ester and analogous
P ketone derivatives (the hydrochlorides are mixed in equivalent quantity with
acetoacetic ester and 10 per cent, sodium hydroxide) {Pinner, Berichte, 22,
1612, 1633; 23, 3820):—

CH
,NH CO.CH3 N— C^

R.c<; +1 = R.cr: ^ch + r'.oh -fH^o.

^NH, CH,.CO,R' -\n=C(

Alkyl methyl-oxy-pyriinidine.

^.y^s^See Berichte, 22, 2610 for the course of the reaction. Alkyl oxypyrimidine

OXAZINE AND MORPHOLINE GROUP. 957

carboxylic acids are analogously derived by the use of oxalacetic ester,

*"*^\ CH^ CO R Dibasic ketonic acids, such as aceto-glutaric ester and diaceto-

succinic ester, react similarly, while succino-succinic ester forms a quinazoline
derivative [BericA/e, 22, 2623 ; 23, 2934.)

The oxypyrimidines are crystalline substances, soluble in nearly all solvents,
and form salts both vfith acids and bJses.

Dimethyl-oxypyrimidine, CH3.CNjC3H(OH).CH3, forms needles that melt
at 192°. Phenylmethyl-oxypyrimidine, C5H5.CNjC3H(CH3).OH, from
benzamidine, melts at 238°.

Uracyl, C4HJN2O2, and its derivatives, as well as malonyl urea, alloxan and the
analogous carbamides, may be viewed as ;J^^o-derivatives of the kydrometadiaaines
[Berichte, 23, Ref. 643.)

(3) All compounds obtained by the condensation of phenylhydrazine ( i molecule)
with diaceto-succinic ester (a 7-diketone, p. 328), appear to be derivatives of ortho-
diazine or pyridazine in which the two N-atoms of the " six-membered " ring
are adjacent (p. 954) (Berichte, 18, 305, 1568) : —

CH,.CO.CH.CO,R

•I =

CH,.CO.CH-CO,R

C,H,.NH.NH,+ I =C,HN,(CeH,)(CH3),(CO,R),+2H,0.
l.CI

If the ester be saponified and two molecules of carbon dioxide eliminated
phenyldimelhylpyridazine, CjH5N2(CgH5)(CHj)2, results. Acetophenone-ace-
tone, CjH5.CO.CH2.CH2.CO.CH3, and phenylhydrazine yield an analogous
compound (^Berichte, 17, 914).

The benzoiriazines, CgH^iNjCH, are the only known derivatives oi triazine,
C3H3N3 (p. 553).

The osotetrazones described (p. 326) may be considered as tetrazines, CjH^Nj.

OXAZINE AND MORPHOLINE GROUP.

The oxazine ring is related in the same manner to the diazine and pyridine ring,
as oxazole to diazole and pyrrol (p. 555) : —

/CH:CH\q jj /CH2.CH2\o

"^\CH:CH/'^ "^\CH2.CH2/^-

Oxazine. Morpholine.

Thus far an oxazine ring, similar to that just given, has only been shown to be
present in the phen- or benzazoxines. Tetrakydro-oxazine, on the. other hand,
does exist. It is called morpholine; verj probably because it is contained in mor-
phine (Knorr, Berichte, 22, 2081).

Morpholine, C^HjNO, tetrahydro-oxazine, is formed when dioxyethylamine,

^'^•V CH^ Ch" OH ' '^ lieated to 160° with hydrochloric acid, or boiled with

alkali.

re-Methyl Morpholine, C^H4(CH3)NO, is similarly formed from dioxyethyl-
methylamine, CH3.N(CH2.CH2.0H)2. It is a liquid, boiling at 1 17°. It is very^
similar to methyl piperidine.

»-Phenyl-morpholine, C^Hj(CjH5)N0, is obtained from dioxyethyl aniline,
C5H,.N(CH,.CH2.0H),, melts at 53°, and boils at 270° {Benchte, 22, 2094).

958 ORGANIC CHEMISTRY.

PYRONE GROUP.

The pyrone ring contains six members. It is analogous to the furfurane ring ;
but is less stable, owing to the influence of the CO-group, and in different reac-
tions it readily breaks down into its components : acetone, acetic acid and oxalic
acid. The conversion of most pyrone derivatives, by the action of ammonia,
into derivatives of y-pyridone (p. 945) and pyridine, is considered rather re-
markable : —

=CO<CH=cg>0 CO<CH=CH>NH CH/Cg=CH\^

i i

Pyrone. 7-Pyridone. Pyridine,

The following compounds are probably derivatives of the pyrone nucleus : —

Pyrone, CjH^Oj, Pyrocomane, is formed when comanic and chelidonic acids
are heated to 250°. One or two molecules of carbon dioxide are eliminated (Be-
richte, 17, Ref. 423). It is a neutral solid that dissolves quite readily in water. It
melts at 32.5°, and boils about 315°.

Dimethyl Pyrone, C5H202(CH3)2 (l, S), results upon heating dehydracetic
acid (see below) with hydriodic acid. Two molecules of carbon dioxide are ex-
pelled from the acid. Brilliant crystals, that melt at 132° and boil at 248°. It
sublimes at 80° in long needles. It is very soluble in water ( Berichte, 22, 1570).
Boiling baryta water converts it into diacetylacetone (p. 328), which ammonia
changes to lutidone.

Oxypyrone, C5H302(OH) (?), pyrocomenic acid, pyromeconic acid, is ob-
tained by the elimination of one or two groups of carbon dioxide from comenic
and meconic acids by distillation. It crystallizes in large plates, melting at 121°.
It boils at 228°, and even sublimes at 100°. It forms unstable salts with one
equivalent of the bases {Jour. pr. Chem., 27, 260).

Comanic Acid, C15H4O4 = C5H3O2.CO2H, PyrOne Carboxylic Acid, is ob-
tained from chelidonic acid l5y the loss of carbon dioxide (Berichte, 18, Ref. 381).
It dissolves with difficulty in water. It melts at 250°, and deconiposes into carbon
dioxide and pyrone. When boiled with lime it decomposes into acetone, oxalic
acid and formic acid. It forms an oxypicolinic acid when digested with ammonia ;
this breaks down into carbon dioxide and pyridone when it is heated.

Chelidonic Acid, C^H^Og = CgH202(C02H)2, pyrone dicarboxylic acid,
occurs together with malic acid in Chelidonium majus. (Preparation, Annalen, 57,
274). It crystallizes in silky needles with one molecule of H^O, and melts at 220°.
It is a dibasic acid, and forms colorless salts. An excess of alkali converts it
into xanthochelidonic acid, C^HgOj. This yields yellow-colored salts with
three and four equivalents of the bases ; chelidonic acid is again liberated from
them by the addition of acids [Berichte, 17, Ref. 424).

The reduction of chelidonic acid gives rise to hydro-chelidonic acid,
C,Hi„05, identical with acetone diacetic acid, CO(CH2.CH2.C02H)2 (p. 437;
Berichte, 22, Ref. 681). Boiling hydriodic acid reduces chelidonic acid to
apimelic acid (p. 421). It does not form an acetoxime with hydroxylamine.
Ammonia converts it into an oxy-pyridine dicarboxylic acid, CjHjNOg (cheli-
damic acid, p. 948).

Coumalic Acid, CjH^O^, is identical with comanic acid. It is probably a

CO— CH = C.COjH
lactone carboxylic acid, with the following constitution, | | ,

O— CH = CH
and may be regarded as a carboxylic acid of a-pyrone [Berichte, 22, 1419, 1705).

DIMETHYL PYRONE DICARBOXYLIC ACID. 959

It is produced when malic acid is heated together with concentrated sulphuric
acid or with zinc chloride (p. 465) (Berichte, 17, 936, 2385). It dissolves with
difficulty in cold water, and melts with decomposition at 206°. With an excess of
alkali it forms yellow- colored salts.

Comenic Acid, CgH^Oj = CsHjOjCOHj.COjH, oxypyrone carboxylic acid.
When meconic acid is heated to 1 20-200°, or boiled with water or hydrochloric
acid, it decomposes into CO^ and Comenic Acid. The latter is rather insoluble in
water, and crystallizes in hard, warty masses. When digested with ammonia it
changes to dioxypicolinic acid (comenamic acid, p. 947). {Berichte, 17, Ref.
105, 167).

Meconic Acid, C,H^O, = C5H02(OH)(C02H)2, oxypyrone dicarboxylic
acid, occurs in opium in union with morphine. The opium extract is saturated
with marble, and calcium meconate precipitated by calcium chloride [Annalen, 83,
352). The salt is afterwards decomposed by hydrochloric acid. The acid crys-
tallizes with 3H2O in white laminae, which dissolve readily in hot water and alco-
hol. When heated to 120° it decomposes into carbon dioxide and comenic acid.
Ferric salts color the acid solutions dark red.

In forming salts the acid generally combines with two equivalents of the bases,
although with an excess of base, the salts are tribasic and yellow in color.

Meconic acid also unites with ammonia, forming Comenamic Acid (Berichte,
17, 2081).

Dehydracetic Acid, CgHgOi = CHj.C O C.CH3

II II ? i^te. Berichte,

CH — CO — C.COjH.
23, Ref. 463; Annalen, 257, 253.)

This is a by-product in the preparation of aceto-acetic ester. It can be obtained
by long continued boiling of the ester, using at the time a return condenser. It
dissolves with difficulty in cold water and alcohol. It crystallizes in needles from
ether; these melt at 108° and boil at 269°. Being a ketonic acid it can unite with
both hydroxylamine and pheayJhydrazine [Berichte, 18, 4.53).. It forms (l, 5)-
dimethylpyrone on being heated with hydriodic acid.

Iso-dehydracetic Acid, CgHjO^, is isomeric with the preceding and may be
obtained by the decomposition of the condensation product, Cj3H2 209 (Annalen,
222,9), produced by the action of sulphuric acid upon acetoacetic ester. It is
identical with carbaceto-acetic acid (Berichte, ig, 2402), derived from the aceto-
acetic acid by means of hydrochloric acid. It is very probably mesiten-lactone
carboxylic acid (Berichte, 23, Ref. 734).

Dimethyl Pyrone Dicarboxylic Acid, C^HjOg Carbonyl Diacetic Acid. Its
ethyl ester is produced when COClj acts upon the copper compound of aceto-acetic
ester. Water is eliminated from the carbonyl diacetoacetic ester which is formed
at first (Berichte, 19, 20) : —

CH,.CO CO.CH3 CH3.C — O — C.CH3

I 1 yields II II

RO,.C.CH — CO — CH.CO.R RO,C.C — CO — C.CO,R.

The diethyl ester is crystalline, very readily soluble in alcohol and ether, and
melts at 80°. Ammonia converts it into dimethyl pyridone-dicarboxylic ester
{Berichte, 20, 154).

g6o ORGANIC CHEMISTRY.

2. QUINOLINE GROUP— C,H2„_nN.*
QUINOLINE, CjHjN.

Lepidine, CioHgN = C9H5(CH,)N— Methyl quinoline.

Cryptidine, CnHi,N = C9H5(CH3)2N — Dimethyl quinoline, etc.

The quinoline bases occur with those of pyridine in bone-oil
(p. 938), and are also obtained by distilling alkaloids (quinine,
cinchonine, strychnine) with potassium hydroxide. The com-
pounds leucoline, C9H7N, iridoline, C10H9N, etc., separated from
coal-tar are identical with the quinoline bases {^Berichie, 16, 1847).

As regards synthetic methods and isomerides, quinoline is a
naphthalene in which a CH-group is replaced by N (p. 937).

This was first shown by synthesizing quinoline from allyl aniline (p. 602), by
passing the latter over ignited lead oxide. This is perfectly analogous to the syn-
thesis of indol from ethyl-aniline (p. 827, and of naphthalene from phenyl bu-
tylene (p. 905) (Konigs) : —

.N =CH
C,H5.NH.CH,.CH:CH, = C,H / | + 2H2.

^CH = CH

Quinoline is also produced in the distillation of acrolein-aniline (p. 602). A
more direct proof of the constitution of quinoline was effected through its forma-
tion from hydrocarbostyril - (p. 755); PCI5 converts the latter into a dichloride,
which upon heating with hydriodic acid yields quinoline (just as isatin yields
indigo, p. 836) (A. Baeyer, Berichte, 12, 1320) : —

CeH,/CH,.CH,\co C,H,(^H:CCl\cci G,^/^^^^CR.

Hydrocarbostyril. a^-Dichlor-quinoIine. Quinoline.

Here, as with naphthalene and pyridine, we represent the. three
replaceable hydrogen atoms of the pyridine nucleus by a, /J and y;

4 r

2

I N

those of the benzene nucleus with i, 2, 3 and 4.f The positions i,
2, 3 correspond to the ortho-, meta-, and para-positions of the
benzene derivatives. 4 corresponds to the second meta position
(referred to N), and is known as the .^«a-position. These posi-

*A. Reissert, Das Chinolin und seine Derivate, 1889.

f Another nomenclature designates the affinities of the pyridine nucleus as Py-I,
-2, and -3; those of the benzene nucleus as B-i, -2, -3, and -4 (Berichte, 17, 960).

QUINOLINE. 961

tions are designated as the affinities of the benzene nucleus with o-,
m-, p- and a-. Consequently, seven mono-derivatives of quinoline
are possible (^Berichte, ig, Ref. 443).

Of the great number of new synthetic methods of preparing
quinoline and its derivatives the following are the most important :

1. The condensation of the ortho-amido-compounds of such
benzene derivatives as have an oxygen atom attached to the third
carbon atom of the side-chain (p. 755) (A. Baeyer).

In tbis way we obtain quinoline from o-amido-cinnamic aldehyde, a-methyl-
quinoline from o-amido-cinnamic ketone, and a-oxy-quinoline from <7-amido-
cinnamic acid (p. 812). Further, o-amido-benzyl acetone yields a-methyl-hydro-
quinoline (p. 730), o-amido-phenyl valeric acid, ;3-ethyl hydrocarbostyril (p. 814),
and from these compounds the normal quinoline derivatives — a-methyl quinoline
and /3-ethyl quinoline — can be obtained by the withdrawal of 2H or O.

2. The production of quinoline and its derivatives by heating
anilines (or amido-benzene compounds) with glycerol and sulphuric
acid to about 190°. This method is of universal application and
can be very readily executed (Skraup, Berichte 14, 1002) : —

CeH,.NH, + C3H,03= C,H,N(C3H3) + ^H^O-f-H,.

It is very probable that acrolein first results, this then combines with the aniline
derivative yielding acroleln-aniline (see above), which is oxidized to the quinoline
derivative by the elimination of two hydrogen atoms by sulphuric acid. Hence,
the reaction proceeds more easily and rapidly by using a mixture of aniline with
nitrobenzene, which only oxidizes. Similarly, from the three toluidines (and
nitrotoluenes) we obtain the three methylquinolines (toluquinohnes), Cj|,HjN =
C5H3(CH3)N(C3H3), from the naphthylamines (and nitronaphthalenes) the
naphthoquinolines, Cj3HgN, and from the diamidobenzenes (and dinitrobenzenes)
the phenanthrolines (p. 974). It is not necessary to apply the corresponding
nitro-compounds together with the amido-derivatives; nitro-benzene mostly suffices
as an oxidizing agent {Berichte, 17, 188). "

Likewise, the chlor-, brom-, and nitro-quinolines result from the corresponding
aniline derivatives. The nitranilines yield both nitro quinolines and phenanthro-
lines [Berichte, 14, 2377). From the amido-sulphonic acids arise the quinoline
sulphonic acids ; from the amido-benzoic acids, quinoline carboxylic acids ; from
the amido-phenols oxyquinolines, etc.

The Kekule benzene formula confirms the course of these quinoline syntheses -
(p. 563) {Berichte, 23, 1020).

3. An analogous reaction is the condensation of anilines with
paraldehyde, aided by sulphuric or hydrochloric acid. Here
a-methyl quinolines (quinaldines) are produced (Doebner and v.

Miller) : —

.CH; CH
CjH^.NH, + 2C,H,0 = C^H / | -f 2H,0 + H,.

^N:C(Crigj
a-Methyl Quinoline.

All aldehydes of the formula CHO.CHgR react like ferric

962 ORGANIC CHEMISTRY.

aldehyde with anilines. The first step in the reaction consists in
two molecules combining to unsaturated aldehydes, CHO.CR:CH.
CHjR, or condensing to aldols corresponding to them. These
then act upon the anilines and form quinoline bases.

Two aldehyde molecules always act. Their condensation is due to the influ-
ence of the CHj group attached to the aldehyde group. Acetaldehyde yields
crotonaldehyde, CHO.CHiCH.CHj, propyl aldehyde yields methyl ethyl acrolein,
CHO.C(CH3):CH(C2H5), and ethyl propyl acrolein is formed from normal
butyraldehyde. These unsaturated aldehydes (or the aldols) then react with the
anilines in such manner, that the aldehyde group attacks the benzene nucleus
(and not the amido-group). Thus, u- or a/3-alkyl quinolines {^Berichte, 17, 1713 ;
18, 3360) result. Acetaldehyde (crotonaldehyde) forms a methyl quinoline (see
above), a/3- ethyl- methyl quinoline [Berickte, zi, 299) is derived from propyl
fildehyde : —

C.H5.NH, + CH0.C(CH)3 .CH: C.CH,

II =CeH/ I +H,0+H,.

cii{c^n^) \n=c.qh5.

a/S-Ethyl Methyl Quinoline.

In oxidizing these dialkyl quinolines with a chromic acid mixture it is only the
ffi-alkyl that is changed tfl carboxyl ; the resulting carboxylic acids eliminate carbon
dioxide and yield /3-alkylquinolines [Berichte, 18, 3370).

Unsaturated aldehydes, therefore, react (with one molecule) directly with the
anilines. Acrolein (glycerol, see above) yields quinoline, while a-phenyl quino-
line {Berichte, 16, 1664) is derived from cinnamic aldehyde, CHO.CHiCH.CjHj.
z«-Nitrocinnamic aldehyde reacts similarly {Berichte, 18, 1902).

Acetone (two molecules) reacts in the same manner as the aldehydes with
aniline hydrochlorides when aided by heat. It is very probable that mesityl oxide,
CH3.CO.CH:C(CH3)j, is the first product; therefore, as there is a simultaneous
splitting off of one mesityl group, the products are ay-dimethyl quinolines
{Berichte, 18, 3296; 19, 1394).

The mixture of an aldehyde and ketone (each one molecule) re-
acts the same as the aldehydes upon anilines. The intermediate
products are unsaturated ketones, R.CO.CH:CH.R (or /J-aldol
ketones, R.C0.CH2.CH(0H)R (C. Beyer, Berichte 20, 1767 ; ig,
Ref. 327). In this way a;'-dialkyl quinolines are produced.

Acetone and acetaldehyde, or acetylacetone, and aniline yield ay-dimethyl-
c^vaoXxnt (Berichte, 21, Ref 138) : —

CHj CH3

CjHj.NH^ -I- CO.CH3 =C^/ ^CH +2H.O-I-H,.

\ I
CHO.CH3 N=C.CH3

The /3-diketones react similarly {^Berichte, 20, 1 770; also a mixture of two
different aldehydes, Berichte, 20, 1908, 1935).

a-Alkyl-quinoline-y-carboxylic acids are produced by the interaction of a mixture

QUINOLINE. 963

of pyroracemic acid and an aldehyde upon aniline (Berickte, 20, 277; 21, Ref.
12):—

CO.H
CO,H I

C.Hj.NH, + CO.CH3 = C5H/ '''^CH + 2H,0 + Hj.

CHO.R \ C.R

N

The carboxylic acids lose carbon dioxide and in this manner the a-alkyl quino-
lines are produced. Pyroracemic acid alone when heated with aniline yields the
same a-methyl quinoline-y-carboxylic acid (aniluvitonic acid, p. 972) ; this is be-
cause aldehyde is formed from one molecule of the pyroracemic acid (Berickte,
20, 1769).

4. The direct condensation of amido-benzaldehyde with alde-
hydes and ketones (by the action of caustic soda). The ortho-
amido-derivatives of the unsaturated homologous benzaldehydes and
ketones are the first products. These immediately give up water
(see p. 721) (Friedlander, Berickte, 16, 1833).

Thus, with acetone we get a-methyl-quinoline: —

CfiHiC + I =C.H,'-"-^" +2H,0;

^NH, ^CO.CH^ " 'N :CCH3 ^ ^

with acetophenone, CHj.CO.CgHj, a-phenyl quinoline; with phenylethyl
aldehyde, CgHj.CHj.CHO, /3-phenyl quinoline; with aceto-acetic ester, a-m ethyl
quinoline-/3-carboxylic acid (Berichte, 16, 1833) ; with malonic ester a-oxyquino-
line-|8-carboxylic acid [Berickte, 17, 456). tf-AmidObenzophenone (p. 859) reacts
just like o-amidobenzaldehyde ; it yields ay-methyl phenyl quinoline with acetone
and caustic soda [Berickte, 18, 2405) : —

CeH / + I =C,H / I

\nHj CO.CH3 ^N CCHg + aHjO.

In acid solution it is only the amido group that takes part in the reaction ; ac-
cording to Miller's reaction benzoyl-a-methyl quinoline results.

5. The condensation of aceto-acetic esters with primary and secondary anilines
(L. Knorr, Berickte, 17, Ref. 147; Annalen, 236, 112).

There are two phases in this reaction : (a) aceto-acetic anilide (from aniline and
aceto-acetic ester when heated to 1 10°), when acted upon with concentrated acids,
forms a-oxy-y- methyl quinoline (y-methyl carbostyril, p. 968) : —

C0(CH3)CH, ,C(CH.):CH

'\ ^ = C,h/ '' \ +H3O.

CjH5(NH).C0 ^N . C(OH)

Methyl aceto-acetic anilide by the same treatment yields /3y-dimethyl carbostyril
[Berickte, 21, Ref. 628).
[b) On the other hand /3-phenyl-amido-crotonic ester, formed at the ordinary

964 ORGANIC CHEMISTRY.

temperatures, yields /-oxy-a-methyl quinoline (y-oxyquinaldine, p. 970) when
heated to 240° (Conrad and Limpach, Berichte, 20, 945, 1397) : —

.C(OH):CH
= C,h/ I +C,H5.0H,

CjHj.NH.C.CHj ^TST rCHj

Phenyl-lutidone carboxylic ester is for(ned simultaneously. Anisidine, CjH^
(O.CH3).NH2, also affords methoxy-y-oxyquinaldine [Berichte, 21, 1649, 1655).
Aceto-acetic ester and methylaniline condense to «-methyl lepidone (= pseudo-
carbo-styril, p. 968) (Annalen, 236, 105; Berichte, ig, Ref. 827) : —

CH3.CO.CH2 .C(CH3):CH

^^ =CeH/ I +H,0.

C5H5.N(CH3).CO \N(CH3).C0

Acetone dicarboxylic ester (p. 435) reacts in an analogous manner with aniline
(and methyl aniline) ; the products in this instance are esters of 7-oxyquinaldine-
^-carboxylic acid [Berichte, 18, Ref. 469).

At the ordinary temperature benzoyl acetic ester and aniline yield /3-phenyl-
amido-phenylacrylic ester, which heated to 250° forms y-oxy-a-phenyl quinoline
(Berichte, 21, 521, 523).

6. By the rearrangement of the aniline malonates or the malonanilides with
PCI5 ; triquinolines being produced (analogous to the formation of a-naphthol
from phenylisocrotonic acid, Riigheimer, Berichte, 18, 2975) : —

CC1=CC1
CeH5.NH.CO.CH2.CO2H yields CjH^/ | .

\ N = CCl

The toludines react similarly to aniline [Berichte, 18, 2979), and ethyl malonic
acid deports itself the same as malonic acid [Berichte, 20, 1235). Hippuric acid,
CjHj.CO.NH.CHj.COjH, under like treatment, yields chlorisoquinoline, (p.
976).

7. By rearranging the anil benzenyl compounds, from benzanilid-imide chlorides
and sodium malonic or aceto-acetic ester, by the aid of heat (Just, Berichte, 19,
979, 1462, 1541):—

RO.OC.CH.COjR /C(OH) = C.CO^R

I =c,h/ /

CeH5.N:C(C,H5) ^^=.Z.Q,Vi,

a-Phenyl-7-oxy-/3-quinoline carboxylic acid.

8. The conversion of indol and alkyl indols into quinolines (p. 830) is rather re-
markable. It occurs in consequence of the Introduction of methyl, dihydroquino-
lines resulting (E. Fischer, Berichte, 21, Ref. 17). Chlor- and brom-quinolines
are similarly obtained by heating methyl ketol with chloroform or CBrjH and
sodium ethylate [Berichte, 21, 1940).

The quinoline bases are liquids which dissolve with difificulty in
water, alcohol and ether, and possess a penetrating odor. Like
pyridine they are not readily attacked by nitric or chromic acid ;

QUINOLINE. 965

potassium permanganate, however, destroys the benzene nucleus in
them, with production of a/3-pyridine dicarboxylic acid (quinolinic
acid, p. 947).

The homologous quinolines, containing the alkyl groups in the
pyridine nucleus (a, ^, ;-), and those containing the substitutions in
the benzene nucleus {o, m, p, a), are oxidized by chromic acid in
the presence of sulphuric acid to the corresponding quinoline car-
boxylic acids, while potassium permanganate on the other hand
usually oxidizes those substituted in the benzene nucleus, with the
formation of pyridine carboxylic acids {Berichte, 19, 1194; 23,
2252).

Potassium permanganate converts the ^- and y-alkyl quinolines (by decomposing
the benzene nucleus) into the corresponding pyridine tricarboxylic acids, while the
(z-alkyl quinolines have their pyridine nucleus destroyed, and acid derivatives of
o-amidobenzoic acid result. By this treatment a-phenyl quinoline yields benzoyl

anthranilic acid, CgH^/^jl r/-) r; jj {Berichte, ig, 1196).

If two methyl groups are present in quinoline, the 7-position will be oxidized
with the most ease, then the /3, and finally the a-position {Berichte, 23, 2254).

In the case of the aj3-dialUylquinoIines, obtained by the action of aldehydes
(2 molecules) upon the anilines, chromic acid only attacks the higher o-alkyl with
the formation of ^-alkyl-a-carbonic acids (see above).

Only the most important of the many derivatives of quinoline
will receive notice in the succeeding paragraphs.

Quinoline, CgHjN, occurs in bone oil and coal tar. It results
when many alkaloids are distilled, and is best prepared syntheti-
cally.

In preparing quinoline, digest a mixture of 38 grams aniline, 100 grams sul-
phuric acid, 24 grams nitrobenzene, and 120 grams glycerol, until the reaction
commences. Boil them for several hours, dilute with water, distil off the nitro-
benzene in a current of aqueous vapor, supersaturate with alkali, and distil the
quinoline with aqueous vapor. To purify it thoroughly convert it into the acid
sulphate {Berichte, 14, 1002).

See Berichte, 14, 1769, for the reactions and physiological action of quinoline.

Quinoline is a colorless, strongly refracting liquid, with pene-
trating odor. It boils at 239°; its sp. gr. = 1.095 ^' 20°. It
forms crystalline and very soluble salts with one equivalent of
acids; the characteristic bichromate, (CgH,N2)Cr207H2, dissolves
with difficulty and forms yellow needles, melting at 165°-

With the alkyl iodides quinoline, as tertiary base, produces crystalline, yellow
ammonium iodides, which may be converted into peculiar bases (ammonium hy-

966 ORGANIC CHEMISTRY.

droxides), soluble in ether, on warming with caustic soda (Berichte, 17, 1953, and,
18, 410, 1015). Tertiary dihydroquinolines also afford bases soluble in ether,
while the iodomethylates of tertiary tetrahydroquinolines are stable towards alkalies
(^Berichte, 21, Ref. 17). Potassium permanganate oxidizes the ammonium chlo-
rides, the pyridine nucleus being decomposed, and derivatives of o-amidobenzoic
acid are produced (see above).

Cyanine (C29H35N2I) is a blue dye, and was formerly prepared by heating
quinoline amyl iodide with potassium hydroxide. It is only produced in the
presence of a-methyl quinoline (Berichte, 16, 1501, 1847) ; the same is true of the
red-dye (Berichte, 16, 1082) obtained from quinoline with benzotrichloride.

Quinoline betaine, C^^(^^^Q,0 (the HCl-salt), is formed from

quinoline and chlor-acetic acid; the free betaine melts at 171°.

Nascent hydrogen (tin and hydrochloric acid) produces Dihydro.-quino-
line, CgHgN (melting at 161°), and liquid Tetra-hydro-quinoline, CgHjjN

= CsHj/^w'-^g^^, boiling at 245° (Berichte, 16, 727, 23, 1 142). Both are

secondary bases and form nitrosamines. The tetrahydronitrosamine rearranges
itself quite readily to the paranitroso compound, which yields p amidoquinoline
when reduced (Berichte, 21, 862). The alkyl iodides and tetrahydroquinoline
yield »-alkylhydroquinolines. M-Methyl tetrahydroquinoline, CjHi„N.(lIL,
so-called Kairoline, obtained by means of methyl iodide, is said to have the same
action as kairine — a febrifuge.

Tetrahydroquinoline (unlike piperidine, p. 950), does not react with bromben-
zene. 'When heated with nitro-benzene it is readily oxidized to quinoline (Be-
richte, 22, 1389).

In tetrahydroquinoline the four hydrogen atoms are attached to the pyridine
nucleus, therefore like the ar-tetrahydro naphthylamines it possesses the character of
an aromatic base (of an aniline). Decahydroquinoline, CgHjjN, of alicyclic
"^aracter, is produced when the preceding compound is further reduced by heat-
itig with hydriodic acid. It is strongly alkaline, with a penetrating, conine-like
odor. It melts at 48° and boils at 204° (Berichte, 23, 1142).

The diquinolyls, CgHjN.CfHjN, result from the union of two molecules of
quinoline. They are analogous to the dipyridyls. They consist either of two
pyridine nuclei, two benzene nuclei or one pyridine nucleus and one benzene
nucleus. Seven isomerides have been prepared thus far, partly through the con-
densation of quinoline by sodium, or by conducting it through a tube heated to
redness. Skraup has succeeded in synthesizing them from benzidine and dipheny-
lin (p. 961), or from amidophenyl quinolines.

On heating quinoline with sodium in air we get a-Diquinolyl, melting at 176°
(Berichte, 20, Ref. 327.) The two pyridine nuclei in it are united to each other
at the a-positions (Py a-Py a) CjII^ : CjH^N— CjH^N : CjH^ (Berichte, 19, Ref.
7S5; 20, Ref. 471).

The chlor-, brom-, and nitro-quinolines, with the substitutions in the benzene
nucleus, are prepared synthetically, by Skraup's reaction, from the chlor-, brom-,
and nitro-anilines. a-Chlorquinoline, C5H5CIN, is obtained from a-oxyquino-
line with PCI5 and PCI3O ; it consists of long needles, fusing at 38°, and boihng
at 266°. It is a feeble base. Its halogen atom, in the a-position, is very reactive.
When heated to 1 20° with water it regenerates a-oxyquinoline ; alkyl ethers appear
when it is acted upon by sodium alcoholates. It reacts in the same manner with
anilines (Berichte, 18, 1532). See Berichte, 21, Ref. 232 for the action of
bleaching lime upon quinoline and the chlorquinolines. Consult Berichte, 23,
Ref. I to upon bromquinolines

Ortho and meta (or ana)- Nitroquinolines, CgHj (N02)N, are produced when
quinoline is nitrated at 80° with a mixture of nitric and sulphuric acids. The

OXYQUINOLINE. 967

ortho- and para- have been obtained from the ortho- and paranitranilines by
means of glycerol and sulphuric acid, while /«-nitraniIine yields phenanthroline
(P- 974)- The ortho melts at 89°, and the meta- (or ana-), when anhydrous, at 72°-

Amido-quinolines, CjH5(H2NjN (substituted in benzene nucleus), are pro-
duced in the reduction of the nitroquinolines with tin and hydrochloric acid and
upon heating the oxyquinolines, C9H,(0H)N, with ammonia-zinc chloride.

I- and 4- Quinoline Sulphonic Acids (ortho- and ana- Berichte, 20, 95),
are formed when quinoline is heated witli fuming sulphuric acid ; at 300 the para
acid is almost the exclusive product, the ortho acid apparently being converted
into this {Berichte, 22, 1390). Ana and para- quinoline sulphonic acids have
been synthetically prepared from meta- and para amido-benzene sulphonic acid
with nitrobenzene, glycerol and sulphuric acid {Berichte, 20, 1446).

When the three quinoline sulphonic acids (their alkali salts) are distilled with po-
tassium cyanide in a vacuum {Berichte, 22, 1391), they yield the corresponding
cyanbenzjuinolines, CgH5N(CN) (l, 3 and 4). The ortho- cyanide melts at 84',
the para (3) sublimes in needles and melts at 131°, the ana (4) melts at 87°
{Berichte, 20, 1447). The cyanides can be saponified by heating ^hem together
with concentrated hydrochloric acid in a sealed tube, when they yield the corres-
ponding quinoline benzcarboxylic acids, C9H5N(C02H).

Oxyquinolines, C9H5(OH)N.

The oxyquinolines containing the hydroxyl in the benzene nucleus, called also
quinophenols (i, 4, and 3, or ortho, meta, and para), are synthesized from
the three amidophenols by Skraup's reaction. I- and 4-Oxyquinolines have also
been prepared from the quinoline sulphonic acids by fusion with caustic potash.
They resemble the phenols and like them combine with diazo-salts forming azo-
dyes {Berichte, 21, 1642).

i-Oxyquinoline (ortho) is also produced from i-chlorquinoline (see above)
and is most readily prepared from l-quinoline sulphonic acid {Berichte, 16, 7 1 2).
It crystallizes in white needles, has the odor of saffron, melts at 75°, boils at 266°,
and is volatile in steam. Ferric chloride imparts a dark-green color to its alcoholic
solution.

Nitrous acid converts it into nitroso-oxyquinoline, yellow-green needles, that by
reduction yi^ds amido-oxyquinoline. I-Oxyquinoline, like the phenols^and naph-
thols, is changed by chlorine to chlorketoquinolines {Berichte, 21, 2977).

Tin and hydrochloric acid convert it into i-Oxytetra-hydroquinoline, CgHg
(OH)NH. This forms shining leaflets or needles, melting at 120°. It yields
oxytetra-hydro-»-niethyl-quinoline, CgHg(0H)N.CH3, melting at 114°, when
it is acted upon by methyl iodide. The hydrochloric acid salt of this base,
CiqHjjON.HCI-I-HjO, is Kairine {Berichte, 16, 720), which is applied as an
antipyretic.

3 Oxyquinoline (para), from para-amidophenol, melts at 190° {Berichte, 15,
893). Its methyl estef; para-quinanisol, is prepared from /-amidoanisol by the
reaction of Skraup. It boils at 305°- Nitrous acid converts it into o-nitr.oso-
p-oxyquinoline, which, upon reduction, and further oxidation by ferric chloride,
forms quinoline quinone,C^^(0^^, crystallizing in red-brown needles {Berichte,
21, 1887).

Tin and hydrochloric acid convert 3-oxyquinoline into tetra-hydro-para-quinan-
isol, C9Hi„(O.CH3)N, crystallizing in stout prisms, melting at 42° and boiling
at 283°. Most oxidizing agents {e.g. ferric chloride) color the base and its salts
green. The sulphate and lactate serve as antipyretics, under the name Thallin
{Berichte, 18, Ref. 613, 72.)

968 ORGANIC CHEMISTRY.

4-Oxyquinoline (ana), from para-amidophenol and from 4-quinolme sulphonic
acid, crystallizes in needles or prisms, melting at 235—238° with decomposition.
Ferric chloride imparts a brown-red color to its solution. Tin and hydrochloric
acid convert it into a tetrahydro-compound.

The oxyquinolines, with hydroxyl in the pyridine nucleus, are
more feeble bases and phenols than the oxybenzquinolines.

«-Oxyquinoline, C9H6(OH)N, Carbostyril, the lactime of
<7-amido-cinnamic acid (pp. 810, 812), is most readily obtained by
digesting ^-nitro-cinnamic ester with tin and hydrochloric acid or
alcoholic ammonium sulphide {Berichie, 14, 1916). It may also
be prepared from a-chlorquinoline by heating it with water, and
by digesting quinoline with a bleaching lime solution (JBerichte,
21, 619). It crystallizes from hot water (i : 100) in fine needles,
from alcohol in large prisms. It melts at 198-199° and sub-
limes.

Water decomposes its salts with alkalies and acids. Carbon dioxide separates it
in the form of shining needles from its alkaline solution. Potassium permanganate
oxidizes it to oxalyl anthranilic acid (p. 749). Sodium and alcohol reduce it to
tetrahydroquinoline i^Berichte, 19, 3302). o-Nitrocarbostyril is produced when
o-nitrocoumaric acid (p. 819) is heated together with alcoholic ammonia. It melts
at 168°.

As in the case of oxypyridine or pyridone (p. 945), it is undetermined whether
the lactime or lactam form should be ascribed to a-oxyquinoline ; the ethers, how-
ever, of the two forms, of carbostyril and pseudocarbostyril exist : —

.CH:CH ,CH:CH

C,H / I and C,H / | .

\-N:C.OR ^NR.CO

Carbostyril Ether. Pseudocarbostyril Ether.

The carbostyril or lactime ethers, with the group, N:C(OR),are produced by the
action of the alkyl iodides upon the undecomposed (Na- or Ag-) salts of carbo-
styril ; the pseudocarbostyril or lactam ethers, however, by the action of the alkyl
iodides upon free carbostyril in the presence of alkalies [Berichte, 18, 1528; 20,
2009). The lactam ethers differ from the lactime ethers in being solid crystalline
bodies, not decomposed when heated with hydrochloric acid. The methyl ether
melts at 71°, and the ethyl at 54°.

The lactime ethers are also formed when o-amidocinnamic esters are digested
with alcoholic zinc chloride (p. 812) and by the action of sodium alcoholates upon
a-chlorquinolines. They are aromatic oils, that volatilize in a current of steam.

There are perfectly anologous isomeric ethers of Hydrocarbostyril, derived
from tetrahydroquinoline, CgHjiN.

a -Oxy-y-methyl quinoline, r-Methyl carbostyril, or Lepidone, C.H,

,C(CH3):CH
( I , from acetoacetanilide (p. 963), manifests a similar behavior, n-

\_NH— CO

Methyl lepidone, from acetoacetic ester and methyl aniline, melts at 131°, whereas
methoxy-y-methyl-quinoline is a liquid [Berichte, ig, Ref. 828). y-Oxy-a-methyl
Quinoline, y-Oxyquinaldine, from phenylamidocrotonic ester (p. 963), also fotms
two isomeric ethers (Berichte, 20, 948; 21, 1965).

METHYL-QUINOLINE. 969

When methyl iodide acts upon y-oxy-quinaldine, it forms an iodomethylate, or HI-

,CO CH

salt, from which alkalies separate n-meihyl quinaldone, C^H^: I

\n(CH),.C(

N(CH)3.C(CH3

melting at 175° {Berichie, 22, 78). Compare lutidone.

Kynurine, f}- or y-oxy-quinoline, CgHg(OH)N, is made by heating cynu-
renic acid (oxyquinoline carboxylic acid, p. 973), and by oxidizing cinchonine and
cinchoninic acid with chromic acid (Berichte, 22, Ref. 758). It crystallizes in
needles, containing three molecules of water, and when anhydrous melts at 201°.
It forms quinoline when heated with zinc dust. Potassium permanganate oxidizes
it to oxalylantbranilic acid (cynurenic acid, p. 749). PCI5 converts it into chlor-
quinoline, melting at 34°.

Dioxy-quinolines, C9H5(OH)2N. Two isomerides have been obtained from
chlorcarboslyril. A rathernoteworthy formation of ay-dioxyquinoline is that from
oamido-phenylpropiolic acid (p. 816). Nitrous acid converts it into trioxyquino-
line, C5H^(0H)jN, which may be oxidized to quinisatinic acid by ferric chloride
and this by loss of water yields quinisatin, C5H5.NO3 (p. 765).

Quinoline Homologues.

The monoalkylquinolines exist in seven isomeric forms (p. 961).

(l) The seven isomeric methyl quinolines are all known.

The four quinolines methylated in the benzene nucleus, called Toluquino-
lines, methyl benzquinolines, or lepidines, are obtained by Skraup's reaction
on heating the three toluidines with nitrotoluenes, glycerol and sulphuric acid. In
this way 0- and /-toluidine yield 0- and /-methyl quinoline, while »(-toluidine
affords both the meta- and ana-quinolines. The latter can be separated by means
of their acid sulphates {Berichte, 19, Ref. 442). The isomerism of place of the
meta- and ana-compounds is obtained from the carboxylic acids, corresponding
to them (p. 972). Chromic acid oxidizes all four methyl quinolines to quinoline
benzcarboxylic acids ; while potassium permanganate converts the four isomerides
(by destruction of the benzene nucleus) into a/3-pyridine dicarboxylic acid (p. 947).

Ortho- methyl quinoline (i), from o-toluidine, boils at 248°, the meta- (2) boils
at 250°, the/ara- (3) at 257°, and the ana- (4) at 250°.

The following are methylated in the pyridine nucleus : — ■

«-Methyl-quinoline, QoHgN = C6H,:C3H.,(CH3)N, Quinal-
dine, is formed in the condensation of f-amido-benzaldehyde with
acetone when warmed with sodium hydroxide (p. 963) ; by the
reduction of ^-nitrobenzal acetone (p. 806) ; from ^'-oxyquinaldine,
and by fusing ethyl acetanilide with zinc chloride (^Berichte, 23,
1903). It may also be obtained from aniline by means of ethyl
aldehyde.

The most advantageous course to procure it consists in digesting i part of ani-
line with lyi parts of paraldehyde and 2 parts crude hydrochloric acid, and
then distil the product with sodium {Berichte, 16, 2465, 2600). As much as 25
per cent, of quinoline is found in coal;tar, but if cannot be isolated from it
{Berichte, 16, 1082).

Quinaldine is a liquid with a faint odor resembling that of quino-
line, and boils at 238°. When acted upon by potassium perman-
81

97© ORGANIC CHEMISTRY.

ganate the pyridine ring is broken and acetyl-anthranilic acid
results. Chromic acid oxidizes it to a-quinoline carboxylic acid.

Tin and hydrochloric acid reduces it to Tetrahydro-quinaldine, CjjHjgN,
which also results by the reduction of »-nitrobenzyl acetone (p. 730). It boils
at 247°, is a strong base, and is colored blood-red by oxidizing agents (FeCl,).
Alkyl iodides and quinaldine (also the lepidines) unite to iodomethylates or am-
monium iodides ; the caustic alkalies liberate the ammonium bases, C^Hg (NR)20,
from the latter [Berichte, 21, Ref. 14). When the iodomethylates are heated
in air contact with the concentrated alkalies peculiar red and blue dyestuffs — the
Cyanines — are produced [Berichte, 18, Ref. 17).

Concentrated nitric acid converts quinaldine into o- and m- nitro-quinaldines,
C,„Hg(N02)N, which form 0- and OT-amido-quinaldine by reduction (Berickte,
22, 224).

y-Oxyquinaldine and ?«-methyl-quinaldone (p. 969).

The CHj-group of quinaldine is very reactive. It enters readily into condensa-
tion products with aldehydes (paraffin or benzene class) {Berichte, 20, 2041).
Chloral yields the compound, CgHgN.CHiCH.CClj, melting at 144°; boiling
potassium carbonate converts it into a quinoline acrylic acid, CgHjN.CHrCH.
COjH, while potassium permanganate oxidizes it to a-quinoline aldehyde,
CgHjN.CHO. Hydrobromic acid and soda convert quinoline acrylic acid into
a-quinoline-lactic acid, CgH^N. CH(0H).CH.C02H and its lactone {Berichte,
21, Ref 635). Consult Berichte, 22, 271, upon quinoline acrylic acids and quino-
line aldehydes. Quinaldine and phthalic anhydride yield a beautiful yellow
dye — quinophthalone or quinoline yellow, C5Hj(C202);CH.N.CgH5 (p. 880),
which may be sublimed in golden-yellow needles, melting at 235°- The sodium
salt of its sulphonic acid is the quinoline yellow of commerce. It dyes silk
and cotton a beautiful yellow.

|8-Methyl Quinoline, CgH5(CH3)N, is produced by heating /3-methyl-a-quino-
line carboxylic acid (from a /3-ethyI-methyl quinoline, from aniline and propionic
aldehyde, p. 962) and by the condensation of aniline together with propionic
aldehyde and methylal (p. 962, Berichte, 20, 1916). It boils at 250°. It solidifies
in the cold and melts at 10-14°. Chromic acid oxidizes it to j3-quinoline car-
boxylic acid.

7- Methyl -quinoline, CgH5(CHg)N, Lepidine, occurs together with quinoline
and quinaldine in coal-tar, and is obtained on distilling cinchonine with caustic
potash. It may be synthetically prepared by the condensation of aniline with
methylal (3 parts) and acetone (3 parts), aided by hydrochloric acid, by the method
of V. iSaeyer (p. 962). It possesses an odor like that of quinoline, and boils at 257° ;
it solidifies below 0°. Chromic acid oxidizes it to y-quinolinecarboxylic acid.
Potassium permanganate first produces methyl-pyridine-dicarboxylic acid, and
afterwards pyri'dine-tricarboxylic acid (aj3y).

(2) Dimethyl- and Ethyl-quinolines.

aS-Dimethyl Quinoline, CgH,(CH3)jN, is obtained from a mixture of acet-
and propionic aldehydes (or from tiglic aldehyde) with aniline [Berichte, 22, 267).
/3y-Dimethyl Quinoline, from /3y-dimethyl-carbostyril, melts at 65° and boils at
290°- 0- and /-Oxy-ay-dimethyl Quinolines, CgH4(OH)(CH3)2N, have been
prepared from a- and /-amidophenol with acetone (Berichte, 22, 209). 0- and p-
Toluquinaldine, CgH5(CH3)2N, containing the methylene groups in the benzene
and pyridine nuclei, are obtained from 0- and/-toluidine by means of paraldehyde
{Berichte, 23, 3483). a- and /3-Ethyl Quinoline, C9H5(C2H5)N, are produced 1
(similar to the alkyl pyridines, p. 942) by heating quinoline iodoethylate to 280°

PHENYL-METHYL-QUINOLINE. 97 1

{Berichte, ig, 2995). iS-Ethyl Quinoline is obtained from /3-etliyl hydro-carbo-
styril (p. 814), just as quinoline is prepared from hydrocarbostyril (p. 961); and
from /3-ethyl quinoline-a-carboxylic acid (from a/3- propyl ethyl quinoline, prepared
from aniline and butyraldehyde, p. 962) \Berichte, 18, 3371).

a-Ethyl Quinoline boils at 255-260°, /3-Ethyl Quinoline at 265°, and
y-Ethyl Quinoline at 270-275°. These compounds yield the corresponding
quinoline carboxylic acids when oxidized with a chromic acid mixture.

Consult Berichte, 21, Ref. 138 upon the trimethyl-quinolines.

Phenyl-quinolines, CgHs(C5H5)N.

a-Phenyl-quinoline is obtained from cinnamic aldehyde and aniline upon
heating them with hydrochloric acid to 200° ; also by the condensation of »-amido-
benzaldehyde with acetophenone. It consists of brilliant needles, melting at 84°,
aqd boiling above 300°. Potassium permanganate oxidizes it to benzoyl anthrani-
lic acid (p. 749) {^Berichte, ig, 1 196); while tin and hydrochloric acid convert
it into a tetrahydro-compound CgHj„(C5H5)N. /3-Phenyl-quinoline is pro-
duced in the condensation of o-amido-benzaldehyde with phenyl-acetaldehyde.
It is an oil, which solidifies on cooling.

y-Phenyl-quinoline is formed by heating y-phenyl-quinaldinic acid (from
7-phenyl quinaldine, see below) to 180° {Berichte, 19, 2430). It crystallizes from
pure alcohol in white flakes, melting at 6i°, and distilling at that temperature. It
apparently is the parent. substance of the quinia alkaloids {Berichte, 20, 622).

7'-PhenyI-a-Methyl Quinoline, CgH5(C5H5) (CHjjN, y-phenyl quinaldine,
results in the action of hydrochloric acid upon aniline mixed with acetophenone
and paraldehyde (p. 961), as well as by the condensation of «-amido-benzophe-
none and acetone by means of sodium hydroxide (p. 963) {Berichte, 18, 2406),
alsoby the condensation of benzoyl acetone, CgHj.CO.CHj.CO.CHj, with aniline,
according to Beyer's method {Berichte, 20,771). It melts at 99° and yields
y-phenyl quinoline-a-carboxylic acid when its phthalone is oxidized with chromic
acid. This new acid affords y-phenyl quinoline (see above).

a- Phenyl -7-methyl Quinoline, CgH5(CjH5)(CH3)N, is produced by con-

densing o-amido-acetophenone, CgH^^Z-vry^ ^, and acetophenone with caustic

soda (p. 963) {Berichte, ig, 1036), as well as by distilling flavenol with zinc dust.
It crystallizes in white leaves and melts at 65°.

Upon heating acetanilide, CgHj.NH.CO.CHj, with zinc chloride to 270° (by
condensation of 2 molecules of the ortho-amido-acetophenone which is produced
first), we obtain Flavaniline, Cj^Hj^Nj, applied as a beautiful yellow dye
{Berichte, 15, 1500). It is/-Amido-a-phenyl-/3-methyl-quinoline. It also
results in the condensation of o-amidoacetophenone and /-amido-acetophenone
when digested with zinc chloride {Berichte, ig, 1038). Flavaniline forms colorless
crystals that become yellow on exposure to the air. Its monacid salts are yellow
in color and have been used as dyes {Berichte, 15, 1500). Nitrous acid converts
it into so-called Flavenol, C9H5(CeH40H)(CH3)N, a phenol, which when
heated with zinc dust becomes ay-Phenyl-methyl-quinoline. Potassium
permanganate oxidizes flavenol to ya-metbyl-quinoline-carboxylic acid (p. 972),
and then to methyl pyridine tricarboxylic acid and pyridine tetracarboxylic acid.

972 ORGANIC CHEMISTRY.

Quinoline Carboxylic Acids,

These acids exhibit the character of amido-acids and yield salts with both bases
and acids.

(i) Quinoline Monocarboxylic Acids, CmH^NOj = CgHjN.C02H.

There are four quinoline benzcarboxylic acids or those containing the carboxyl
groups in the benzene nucleus. Of these the ortho, meta and para are obtained
by oxidizing the corresponding methyl quinolines with chromic acid in a sulphiuic
acid solution. The ortho, para and ana-acids are prepared from o-,p- and m-
amido-benzoic acids by Skraup's reaction, heating them with glycerol and sul-
phuric acid to 140°, further, by heating the three cyanquinolines with hydro-
chloric acid (p. 967).

The place-isomerism of the ana-acid (melting about 360°) is evident from its
formation (together with the ortho-acid) from amido-terephthalic acid by Skraup's
reaction (Berichte, 19, Ref. 548), from (I, 2, 3)-amidophthalic acid (together with
the meta-acid) (Berichte, 19, Ref. 548), and from ana-quinoline sulphonic acid
(p. 917) by means of the cyanide (Berichte, 20, 1446). The meta-acid has also
been obtained by oxidizing /3-di-quinolyl {Berichte, 19, 2473).

Ortho-Quinoline-Carboxylic Acid (i) is the most soluble in water and alco-
hol. It crystallizes in white needles, melting at 187°. The meta (2) acid crys-
tallizes in needles, melting at 284-250°. The /ara-acid (3) is a white powder,
and melts at about 291°, charring at the same time. The a«a-acid (4), also pre-
pared from meta-amido-benzoic acid, is almost insoluble in water, sublimes as a
cyrstalline powder, and melts about 360° {338°) (Annalen, 237, 325).

The acids containing the carboxyl in the fyridine nucleus are prepared by
oxidizing a-, /?-, and y-methyl-quinoline with chromic acid in sulphuric acid solu-
tion. Those acids, with a carboxyl in the a-position, are colored reddish-yellow
by ferrous sulphate.

a-Quinoline Carboxylic Acid, C9H6N(CO.iH), Quinaldinic
Acid, crystallizes from hot water in needles containing 2H2O ; it
effloresces in the air, melts at 156°, and further decomposes into
carbon dioxide and quinoline.

j3-Quinoline Carboxylic Acid is produced by heating Acridic acid to 130°.
It crystallizes in small plates, melts at 171°, and when oxidized with potassium
permanganate yields {a, /?, y)-pyridine tricarboxylic acid (p. 949).

)--Quinoline Carboxylic Acid, C9H6N(C02H), Cinchoninic
Acid, was first produced upon oxidizing cinchonine with potassium
permanganate or nitric acid. It crystallizes in needles, containing
2H2O, in thick prisms, or plates with 2H2O {^Berichte, 20, 1609).
It melts when anhydrous at 254°. When distilled with lime it
affords quinoline ; potassium permanganate oxidizes it to a/J;'-pyri-
dine tricarboxylic acid.

Methylquinoline Carboxylic Acids, Cs,H5(CH3)N(C02H).

y-Methyl-n-quinoline Carboxylic Acid is obtained by oxidizing flavenol (p.
971) with potassium permanganate, and melts at 182", with decomposition into
COj and y-methy] quinoline.

a-Methyl-y-quinoline Carboxylic Acid, a-Methyl Cinchoninic Acid, is
Aniluvitonic Acid, obtained by the condensation of pyroracemic acid with aniline

QUINOLINE-DICARBOXYLIC ACID. 973

(p. 962) {Berickte, 22, 1769). It crystallizes in delicate needles containing one
molecule of water. It melts at 240°, and breaks down into carbon dioxide and
quinaldine {Berickte, 14, 2249).

The homologous a-alkyl cinchoninic acids result in the condensation of pyro-
racemic acid and aldehyde with anilines (p. 962) [Berickte, 22, 23).

a-Methyl-/3-quinoline Carboxylic Acid, C5H5N(CH,).C02H results from
the condensation of o-amido-benzaldehyde with aceto-acetic ester (p. 962), and
melts about 234°, with decomposition into carbon dioxide and quinaldine.

The Quinaldine Carboxylic Acids (quinaldines with carboxyl in the ben-
zene nucleus), a-Methyl quinoline-carboxylic acids (ortho, meta and para), are
produced by the condensation of the three amido-benzoic acids with aldehyde and
hydrochloric acid.

(2) Oxyquinohne Carboxylic Acids, CgH5(OH)N)C02H.

a-Oxyquinoline-;3-Carboxylic Acid, Carbostyril-/3-carboxylic Acid, results
in the condensation of o-amido benzaldehyde with malonic acid (p. 963), melts
above 320°, and on heating its silver salt yields CO^ and carbostyril.

a-Oxyquinoline-y-carboxylic Acid, Oxycinchoninic Acid, is formed on
melting cinchoninic acid with potash. It melts at 310°, and decomposes into CO^
and carbostyril, if its silver salt be distilled.

Kynurenic Acid is also an oxy-quinoline carboxylic acid. It occurs in the
urine of dogs. It consists of needles containing iHjO, becomes anhydrous at
140°, and melts at 257°. Fusion with caustic potash converts it into COj and
kynurine.

o-Oxy-quinoline-zH-carboxylic Acid, CgH5(OH)N(C02H), with the hy-
droxyl group in the ortho position of the benzene nucleus, is produced when the
sodium salt of o-oxyquinoline [Berickte, 20, 1217) is heated with COj under pres-
sure (analogous to the formation of salicylic acid) :—

CgHj(ONa)N + COj = CsH5(OH)N(C02Na).

/-Oxyquinoline by the same treatment yields p-oxyquinoline carboxylic acids
[Berickte, 20, 2695). The ortho and para acids have also been obtained from
0- and /-oxyquinoline by means of CCI4 and caustic potash [Berickte, 20, Ref.
564). In the same manner o-oxyquinaldine yields o-oxyquinaldine carboxylic
acid, C9H4(CH3)(OH)N.C02H [Berickte, 21, 883).

Para-oxycinchoninic Acid, C9H5(OH)N(C02H)(3, 7), Xantkoquinic acid,
results on fusing parasulphocinchoninic acid (on heating cinchoninic acid to 260°,
with sulphuric acid) with KOH. It crystallizes with I molecule of H^O, and
melts at 320° with decomposition into carbon dioxide and paraoxyquinoline. Its
methyl phenol ether Quininic Acid, C9H5(O.CH3)N(C02H), is obtained by oxi-
dizing quinine and quinidine with chromic acid in sulphuric acid solution, crys-
tallizes in long, yellow prisms, dissolves in alcohol with a blue fluorescence, and
melts at 280°. When heated to 230° with hydrochloric acid it decomposes into
methyl chloride and para-oxycinchoninic acid. >

3. Quinoline Dicarboxylic Acids, CgH5N(C02H)2.

a/3-Quinoline-dicarboxylic Acid, Acridic Acid, is produced when acridine
is oxidized with potassium permanganate, crystallizes in needles with 2H2O, or
plates with 1H2O, and decomposes at 120-130° into COj and /3-quinoline-carbox-
ylic acid.

ay-Quinoline-dicarboxylic Acid results when a-cinnamenyl-cinchoninic
acid (from cinnamic aldehyde, pyroracemic acid and aniline) is oxidized with

974 ORGANIC CHEMISTRY.

potassium permanganate. It melts with decomposition at 246° (Berichte, 22,
3009).

( 1 , 4)-Quinoline Dicarboxylic Acid is obtained from amidoterephthalic acid
by the action of glycerol and sulphuric acid. It crystallizes in long needles contain-
ing zHjO, melts at 268-270°, and breaks down into carbon dioxide, and ortho-
and ana-quinoline carboxylic acids (p. 972).

Complex Quinolines.

Just as pyridine, C5H5N, and quinoline, C9H5N, are derived from benzene,
C5H5, and naphthalene, CjjHg, so corresponding quinolines result from the
higher, condensed benzenes.

The so-called Naphtho-quinolines, Cj jH^N, are derived from phenanthrene
by the replacement of a CH-group in a terminal benzene ring by nitrogen, whereas
in phenanthridine the N-atom is present in the middle benzene mucleus : —

N

Q:<=>

Q-O

\ / \ /

a-Naphtho-'quinoline,

j3-Naphtho-quinoline,

N
Phenanthridine.

They are produced when a- and j3 naphthylamines are heated with glycerol,
nitrobenzene and sulphuric acid.

a-Naphtho-quinoline melts at 50°, and boils at 251° . ^S-Naphtho-quino-
line, melts at 90°. When they are oxidized, they yield two [a- and /?-) phenyl-
pyridine dicarboxylic acids, CgH^(C02H).C5H3N(C02H) (this is like the forma-
tion of diphenic acid from phenanthrene, p. 925), which split off two molecules of
carbon dioxide and become a- and /3-phenyl-pyridines (950). /3-Naphtho-quinoline
may also be obtained by removing bromine from o-brom-/?-naphthylamine, or by
the elimination of the nitro group from a-nitrO|8-naphthylamine {Berichle, 23, 1018).

/3 Naphthomethyl Quinoline, CijHiiN = CisHj(CH3)N, ;8-naphtho-
quinaldine, is analogously produced by the action of paraldehyde and sulphuric
acid upon /3-naphthylamine. Potassium permanganate oxidizes it to ^-naphtho-
quinoline carboxylic acid, CjgHjN.COjH {Berichte, 22, 254; 23, 1231).

Phenanthridine is isomeric with naphthoquinoline. In it one of the interme-
diate CH-groups of phenanthrene is replaced by nitrogen. It results from the
pyrogenic condensation of benzylidene aniline on conducting the latter through
a tube heated to redness {Berichte, 22, 3339) : —

CgHg.CH CgH^.CH

II = I II +H2.
CSH3.N CeH,.N

It crystallizes in delicate white needles, melting at 104° and boiling without
decomposition at 360°. Its salts are yellow in color.

C5H3N.CH
Two Phenanthrolines, CijHjNj, = | 11 , have been prepared by

C5H3N.CH
heating m- and'/-diamidobenzene with glycerol, etc. These are derived from
phenanthrene by replacement of 2 CH-groups of the terminal benzene ring by 2
nitrogen atoms {Berichte, 16, 2522; 23, 1016).

ISOQUINOLINE ■ GROUP. 975

Phenanthroline, melting at 78°, is obtained from meta-nitraniline and meta-
amido-quinoline by means of glycerol and sulphuric acid. Isomeric Pseudo-
phenanthroline is also derived (in slight amount) from paranitraniline and melts
at 173° Potassium permanganate oxidizes the phenanthrolines to two dipyridyl
dicarboxylic acids {Berichte, ig, 2377). _

Anthraquinoline, C„HiiN= C^H./J^^^CsH / ' I , is obtained

from anthramine (p. 89S) on heating with glycerol, nitrobenzene and sulphuric
acid. It sublimes in colorless leaflets, melts at 170°, and boils at 446°. Its solu-
tions fluoresce very intensely. By oxidation with chromic acid in glacial acetic
acid, it yields a quinone corresponding to authraquinone; the dioxy- compound of
the latter is alizarin blue.

When 7«-nitro-alizarin or amido-alizarin is heated, according to Skraup's re-
action, with glycerol and sulphuric acid we obtain alizarin-blue, Cj ^HuNOj I^Be-
rickte, 18, 44.5) : —

C,,H,(0)2(0H),NH, + CjHA = q,H,(0),(0H),N.C3H, + 3H,0.

The same occurs in trade in the form of a bluish-violet paste, and like alizarin
is applied in dyeing. Since reducing agents decolorize it (zinc dust, grape sugar)
and it again separates on exposure to the air, it is adapted to the vat-dyeing. It
combines with sodium sulphite, yielding a compound soluble in water (same as
quinoline) — the so-called soluble aliiarin-blue (Berichte, 22, Ref. 368).

Alizarin-blue crystallizes from benzene in metallic, blue-violet needles, which
melt at 270° and sublime. Heated with zinc dust it forms anthraquinoline,
Cj,^HuN (see this) ; it is, therefore, a derivative of the latter, and is similarly
obtained from nitroalizarin and glycerol, just as quinoline is derived from nitro-
benzene and glycerol. It unites with acids and bases to form salts ; those with
the bases are stable.

ISOQUINOLINE GROUP.

Isoquinoline is isomeric with and perfectly analogous to quinoline. Its N- atom
occupies the meta-position with reference to one of the two C- atoms, which are
common to both rings. It corresponds to the following scheme : —

^CH = CH
QH / I or

^CH = N

This constitution seems evident from the fact that when isoquinoline is oxidized
it forms cinchomeronic and phthalic acids (see below) ; the syntheses of the iso-
quinoline nucleus also argue in its favor : —

CHj.CO
(i) By heating homophthalimide, CjH^C^ | (p. 791) with POCI3 and then

^ CO.NH
reducing the resulting dichlorisoquinoline by heating it with hydriodic acid
[Berichte, ig, 2354), or by heating homophthalimide with zinc dust (^Berichte, 21,

2299)-

In a like manner dimethyl homophthalimide (p. 791) and zinc dust yield
methylisoquinoline {Berichte, 20, IIOJ; 21, 2300); isophthalamidine,

yCHrC.CgHg
CjH^/ • > f°'''"S ^-phenyl isoquinoline [Berichte, 18, 3477 ; ig, 830) ;

*\

CO.NH

976 ORGANIC CHEMISTRY.

and o-cyanbenzoyl cyanide is converted into benzyl chlor- oxyisoquinoline {Be-
richte, 2i, 2679).

(2) Heating hippuric acid (p. 744) with phosphorus pentachloride and then
reducing with hydriodic acid (Berichte, ig, 11 72). This is analogous to the for-
mation of quinoline from malonanilide (p. 964).

Isoquinoline, C9H,N, occurs together with quinaldine and ordinary quinoline
in the crude quinoline from coal tar. It is separated from the accompanying com-
pounds by the crystallization of the sulphates (Berichte, 18, Ref 384). It is very
similar to quinoline, solidifies however at 0° to a crystalline mass, melting at 20-
22°, and boils at 237°. Potassium permanganate oxidizes it to phthalic acid (de-
stroying the pyridine nucleus) and jiy- pyridine dicarboxylic acid (by destroying
the benzene nucleus), whereas quinoline yields a^- pyridine dicarboxylic acid;
phthalimides, CjH^(C0)2NR {Berichte, 21, Ref. 786), result if the oxidation
be moderated.

A beautiful red dye — Quinoline Red— is, produced by condensing benzotrichlo-
ride, CgHjCCl,, with molecular quantities of quinaldine and isoquinoline when they
are heated with zinc chloride. This compound, in all probability, has a consti-
tution, CgH.CCl^ff," t/^^tt ,T^, analogous to that of malachite-green (Hofmann,

Berichte, 20, 4).

In addition to its coloring properties, it possesses the remarkable power of render-
ing photographic plates orthochromatic.

;3-Phenyl isoquinoline, CgHg(C5H5)N (see above), crystallizes in leaflets,
and melts at 104°.

BENZO-DIAZINES.

These are analogous to the benzopyrrols (p. 826) and benzo-diazoles (p 57')'
They contain both the benzene nucleus and the diazine nucleus, with two carbon
atoms in common (p. 860). They exist, in accordance with the positions of the N-
atoms, in three isomeric forms : —

,CH=CH ,CH=N /N=CH

C, h/ I C^h/ I and C^H, 1 .

^ N=N \ N=CH \N=CH

Ortho-benzdiazines Metabenzdiazines Parabenzdiazines.

Cinnoline. Quinazoline. Quinoxaline.

1. Cinnoline Group.

The Cinnoline nucleus, CgH^Nj, the first representative of the ring-chains
containing two nitrogen atoms, is known in very few derivatives. It has been ob-
tained by a closed ring being formed from the diazo-compounds; a nitrogen atom
enters the side chain occupying the ortho-position.

Thus, Oxy-cinnoline Carboxylic Acid (v. Richter, Berichte, 16, 677,) is ob-
tained from the diazo-chloride of o-amidophenyl propiolic acid (p. 815), when its
aqueous solution is heated to 70° : —

.CiC.CO^H .C(0H):C.C02H

!,( -f H,0 = CgH / /.

\N:NC1 \n : N

Methyl Cinnoline-carboxylic Acid, C6H3(C02H)( / (Wid-

,C(CH3):CH

^N : n''

PHENYLENE-DIAZOSULPHIDE. 977

mann, Berichte, 17, 724), is obtained in the same way, from the diazo-chloride of
o-amido-propenyl benzoic acid (p. 778), CjH3(C02H) | C(CH3):CH

Oxycinnolinecarboxylic acid, C8H4(OH1N2(C02H), melts at 260°, with the
separation of COj and formation of Oxycinnoline, C8H5(OH)Nj, which melts at
225°, and when heated with zinc dust yields cinnoline.

o-Phenylene-diazosulphide, C5Hj(^„ J)N (p. 683), maybe viewed as a cin-

noline derivative, in which a sulphur atom replaces the group CH : CH. It sustains
the same relation to cinnoline that thiophene bears to benzene or benzothiophene
to naphthalene (p. 824).

2. Quinazoline Group.

The quinazolines contain the benzene nucleus and in addition the same ring as
the pyrimidines. They are produced by analogous condensations.

(1) Di-hydroquinazolines (and quinazolines) are obtained from the acidyl de-
rivatives of oamido benzylannne, C8H4{NH2).CHj,.NH2 (p. 710), by condensation,
effected by mere distillation (Gabriel, Berichte, 23, 2808). Thus, o-amidobenzyl-
acetamide yields methyl dihydro quinazoline : —

.CH2.NH .CH^-NH

C^h/ I =QH/ I -fH,0;

^NHj.CO.CHj \N=C.CH3

and o-amidobenzyl formamide, C5Hj(NH2).CHj.NH.CHO, dihydroquinazoline,

-CH = N
while o-amido benzyl benzamide forms/^^»y/^?«'«a2oA'»if, CgH,^
with simultaneous elimination of water and hydrogen. ^ N = C.C5H5

(2) Analogous acidyl compounds are produced by the action of sodium form-
anilides (not acetanilides) upon o-nitro benzyl chloride : —

CH.Cl CeH^ CH,-N.CeH,

CeH^ +NaN( ' = CeH ,( | + NaCl.

^NO^ ^CHO ^NOj CHO

When these are reduced, condensation takes place, and «-phenyl dihydro-
quinazolines are produced (Paal, Berichte, 22, 2683).

The 0 nitrobenzyl anilines yield such acidyl derivatives by the introduction of
formyl and acetyl. Thus, o-nitro benzyl-acetanilide forms methyl-phenyl-dihydro-
quinazoline (Paal, Berichte, 23, 2635, Ref 530) : — ■

C,H / I yields C^H / |

-^NO^.CO.CHs ^N = C.CH3

Condensation does not follow the action of nitrous acid upon the amido-benzyl
anilines (Berichte, 23, 2188, 2636).

(3) Keto-derivatives of the dihydroquinazolines are obtained from o-amido-
benzamide, CjHj(NH2).C0.NHj (irom anthranil carboxylic acid, p. 749, by the
action of ammonia), by introducing acid radicals into it, and then condensing the
resulting acidyl-amidobenzamides (Weddige, Berichte, 20, Ref. 630; Korner,
ibid.) :—

.CO.NH, -CO— NH

C,H / = C,H / I + H,0.

^NH.CO.CHj ^N = C.CH3

Acetyl-(7-amido-benzamide. Methyl-keto-dihydroquinazoline.

82

978 ORGANIC CHEMISTRY.

Benzoyl-amidobenzamide under similar treatment forms phenyl-ketodihydro-
quinazoline.

(4) Keto-derivatives of tetrahydroquinazoline are analogously obtained from
o-amidobenzyl alcohol (p. 709) by converting it into urea derivatives (with CNK
and HCl), and condensing the latter by digesting therti with hydrochloric acid
(Widmann, Berichte, 22, 1668, 2933) : —

.CHj.OH /CHj.NH

CeH / = C,H / I + H,0.

^NH^.CO.NH^ ^NH— CO

Oxytolyl Urea. Keto-tetraquinazoline.

The thioquinazolines are prepared by digesting c-amido-benzyl alcohol with
mustard oils : —

CH,.OH N.C3H5 - CH^.N.CaH,

CaH/ + II = C,h/ I +H,0.

^NH^ CS » NH.CS

Mercuric oxide will convert these new compounds into ketpquinazolines.

(5) Benzoylene Urea, CJH5N2O2, is a dikelo-tetrahydro-quinazoline. It is
obtained from c-amido-benzamide by the action of chlorcarbonic ester, or by
fusing it with urea (Berichte^ 22, Ref. 196) : —

.CO.NH„ .NH, ^CO— NH

/ ■ ' + Cq/ ' = CeH /
^NH, \NH, ^NH— CO

C,H / + C0( = CeH / I + 2NH3.

\ntt_ \i\rw \i>-— —

' It also results in the oxidation of keto-telrahydro-quinazoline with chromic

acid {^Berichte, 22, 2939). When heated with PCL to 160° it yields dichlor-

/CCl = N
quinazoline, CgH^^ j, CCl-^' ^^''^^ regenerates benzoylene urea with water.

3. QUINOXALINE GROUP.

The members of this group are readily synthesized by various reactions (see
Hinsberg, Annalen, 237, 327) : —

(1) By the condensation of the orthophenylene diamines with glyoxal, COH.
COH, and ortho-diketone compounds, R.CO.CO.R. This is effected by digesting
their aqueous solutions (Hinsberg, Berichte, 17, 319 ; Korner, Berichte, 17, Ref.
573). Thus, «-phenylenediamine and glyoxal condense to quinoxaline, the
parent substance : —

NH2 COH N = CH

CbH / + I = C,H / I f 2H,0.

\nH-2 COH \n = CH

Quinoxaline.

w//-Toluylene diamine and glyoxal yield toluquinoxaline, C5H3(CH3)N2CjHj,
while with benzil the product is diphenyl-toluquinoxaline, C|jH.,(CH3)N2Cj
^^i^hji' ^"d with diacetyl dimethyl toluquinoxaline {Berichte, 21, I414).
(ij 2, 4|-Triamido-benzene (p. 625) and glyoxal yield amido quinoxaline.

(2) The action of pyrocatechol upon ethylene diamine when heated to 200° is

QUINOXALINE GROUP. 979

in a measure the reverse of the reaction. The product in this instance is eithtr
tetrahydroquinoxaline or ethylene-o phenylene diamine: —

/OH HjN.CH^ /NH.CH,

+ I =C6H,

\0H HjN.CH^ \NH.i

C,H, + I =C5H, I +2H,0.

-" — -.CHj

Quinoxaline is produced by oxidizing this with potassium ferricyanide (Merz,
Berichie, 20, 1 193; 21, 378).

(3) By the condensation of o-phenylene diamines with oxalic acid, glyoxylic acid,
COH.COjH, a-ketonic acids and analogous dicarbonyl compounds, COR.CO^H.
Thus dioxyquinoxaline results on heating with oxalic acid to 160° : —

/NHj CO.OH

/N = C.OH

CfiH, + 1

: C^H, 1 + 2H,0.

XNHj GO.OH

\N = C.OH

With pyroracemic acid at 60-80° the product is methyl oxyquinoxaline, with
benzoyl carboxylic acid, phenyloxyquinoxaline, and with dioxytartaric acid we get
quinoxaline dicarboxylic acid, etc. : —

/N^C.CHj /N = C.CgH5 /N = C.C02H

CeH, I C,H, I CeH, |

\N = C.OH \N = C.OH \N = C.CO^H

(4) The a-chlor- or brom-carbonyl compounds react just like the a-diketones and
a-ketonic acids. Thus, toluylene diamine and chloracetone form methyl toluquin-
oxaline : —

/NH, CH^Cl /N = CH

. + I =C,H, I

\NH„ CO.CH3 \N = C.CH

+ I =C,H, I + H,0 + H, + HCl;
" = C.C"

and if bromacetophenone be substituted in the reaction two isomeric phenyl tolu-
quinoxalines, C,Hg : N2C2H.CJH5, will result, one of which may also be prepared
from phenacyl nitrotoluidine (Berich/e, 23, 166).

Keto-tetrahydro-toluquinoxaline is formed by the union of chloracetic ester with
toluylene diamine {Annalen, 237, 360; 248, 71) : —

.NH„ CH2CI NH.CH^

C,h/ +1 =C,H,( I + HCl + C,H,.OH.

-NH^ to.O.C^H^ ^NH.CO

(5) An analogous reaction is the reduction of o-nitrophenyl- and o-nitrotolylgly-
cocoll (p. 608) with tin and hydrochloric acid; the resulting amidoacid sustains
a condensation {Berichie, ig, 6 ; 895 ; 20, 24 ; Hinsberg, Berichte, 22, Ref. 12) :—

^NH.CHo.COjH .NH— CH2

C,h/ =.CeH4< I

^NH^ \n = C.OH.

Oxydihydroquinoxaline.

(6) By the action of cyanogen gas upon the orthophenylene diamines, and sub-

g8o ORGANIC CHEMISTRY.

sequent heating of the resulting amide derivative together with hydrochloric acid
to 150° (Bladin, Berichte, 18, 666) : —

.NH„ CN .NH— C:NH .N = C.OH

C^H / + I =C,H / I andC.H / |

^NH^ . CN \NH— C:NH ^N = C.OH.

Dicyan-fj-phenylene Dioxyqiiinoxaline.

Diamine.

The quinoxalines that do not contain oxygen are feeble monacid
bases, generally soluble in water, alcohol and ether. Their odor
resembles that of quinoline. Water decomposes nearly all their
salts. The quinoxaline nucleus is quite stable in the presence of
oxidizing agents, while reducing agents usually effect its decompo-
tion. The tertiary compounds are not affected by nitrous acid. The
quinoxalines result mainly by the simple interaction of their com-
ponents, hence serve as a means of recognizing the ortho-diamines
(p. 626), and also the orthodiketone derivatives by using mp-
diamidotoluene, which is easily obtained (p. 626).

Quinoxaline resembles pyrazine (p. 954) and phenazine (p. 986) in that it con-
tains two nitrogen atoms in the para position of the six-membered nucleus, and con-
stitutes as it were a transition from the first to the latter, with which it has many
analogies so far as methods of formation are concerned. Hence the three groups
are all termed diazines, and quinoxaline is also known as quinazine, inasmuch as
it bears the same relation to quinoline as pyrazine to pyridine. For the nomen-
clature of the complex azines, see Annalen, 237, 330 ; Berichte, 20, 23 and 327.

Quinoxaline, CjHgNj, may easily be obtained from o-phenylene diamine and
glyoxal or its compounds by digesting the aqueous solution at 60°, with sodium
bisulphite. It is a crystalline mass, melting at 27° and boiling at 229° (at 760 mm.].
Its odor resembles that of quinoline and piperidine. It is readily soluble even in
cold water, and when heated, or by the action of alkalies, again separates from its
solution. It is very soluble in acids.

Toluquinoxaline, C3Hs(CH3)N2 = CeHg(CHj):N2C2Hj, obtained from
OT/-toluylene diamine, is a colorless liquid that assumes a brown color on exposure
to the air. It boils about 245°. Methyl Toluquinoxaline, CgH3(CH3):N2.C2H
(CHj), from toluylene diamine and chloracetone, is very soluble in cold water,
alcohol and ether. It melts at 54° and boils about 268°. Dimethyl Toluquin-
oxaline, C5H3(CH3):N2C2(CH3)2, from diacetyl and toluylene diamine, melts at
91° and boils at 270°. Phenyl Toluquinoxaline, C6H3(CH3):N2C2H(CgH5),
from toluylene diamine and chloracetophenone, is scarcely soluble in water and
melts at 135°.

Oxymethyl-toluquinoxaline, C6H3(CH3):N2C2C^q^S is derived from

toluylene diamine and pyroracemic acid (p. 979). It sublimes in colorless needles,
melting at 220°- It dissolves in water with difficulty. It forms colorless solutions
with the alkalies, and with the acids yellow-colored liquids. Oxy-phenyltolu-

quinoxaline, C5H3(CH3):N2C2(^q|, s, from toluylene diamine and phenyl-

glyoxylic acid, crystallizes in yellow needles, that sublime and become white,
melting at 196°. The alkali solutions are colorless, those with acids are yellow in
color.

THifi ACRIDINE GROUP. 981

Dioxytoluquinoxaline, CgHg(CH3):N2C2(^ q5, results upon heating toluylene

diamine together with oxalic acid, as well as from dicyantoluylene diamine (see
above) {Annalen, 2,yj, 348). It dissolves with difficulty in water, forms white
needles, and melts above 300°. It forms salts with bases; water, however,
decomposes them.

Benzotriazines (p. 957) may be obtained from o-nitrophenylhydrazine by reduc-
ing its acidyl derivatives with zinc dust or sodium amalgam. Benzo-lriazine is
thus prepare! from fortnyl nitrophenyl hydrazine [Berichte, 22, 2806) : —

/NO2 ,N— CH

CfiH / + 3H, = CeH,( I li + 3H2O + H^.

^NH.NH.COH ^ N— N

Methyl benzotriazine is similarly derived from the acetyl compound. The
benzotriazines are yellow, crystalline compounds, with a peculiar odor resembling
that of the alkaloids. They are feeble bases. Benzotriazine, CjHjNj, melts at 65°
and boils at 235-240°. Methyl benzotriazine, C,H4.(CH3)N3, melts at 89° and
boils at 250-255°.

Benzoxazines (p. 9S7).

. O. CH2 /O CHj

C,h/ I and C,h/ | .

\N=CH ^NH. CHj

Benzoxazine. Benzmorpholine.

Phenyl benzoxazine, CjH5(C5H5)NO, is obtained from o-nitrophenol-phen-
acyl ether, CsH^(N02).O.CH2.CO.C5H5 (from (j-nitrophenol and bromacetophe-
none), by reduction with stannous chloride and hydrochloric acid. It melts at
103° and is a feeble base (^Berichte, 23, 172).

Benzomorpholine, CgHjNO, Phenmorpholine (see above), may be pre-
pared by heating oxyethyl-o-amidophenol, CjH^(NH2)O.C2Hj.OH (from amidine)
with hydrochloric acid and then with fodium hydroxide (p. 957). It is a colorless
oil, with a characteristic odor. It boils at 2^8°.

Methyl Benzomorpholine, Cj[:fg(CH3)N0, from methyl anisidine, boils at
261° [Berichte, 22, 2098).

THE ACRIDINE GROUP.

The parent substance acridine, QaHgN, is an analogue oi pyri-
dine and quinoline. It is an anthracene, in which N replaces an
intermediate CH-group of normal anthracene. The third affinity
of the nitrogen atom is combined with the opposite carbon atom
(p. 894). The acridines may be synthesized :

(i) From diphenylamine, and the fatty acids, or from the acid

p82 ORGANIC CHEMISTRY.

derivatives of diphenylamine, if they be heated together with zinc
chloride (Bernthsen, Annalen, 224, i ; Berichte, 16, 1820) : —

CHO ^CH^

Formyl Diphenylamine. Acridine.

Homologous acridines are similarly obtained from diphenylamine and the higher
fatty acids. In them the hydrogen of the CH-group is replaced by alkyls. They
are called meso-derivatives (Berichte, 18, 690). mj-Methyl acridines aresimilarly
formed when/ phenyl tolylamine, CgHs.NH.CjH^.CH, (p. 624), is heated
together with acids and zinc chloride (^Berichte, 20, Ref. 376).

(2) An analogous reaction is the rearrangement of dinitro diphenylamine 0-
carboxylic acid (from chlordinitrobenzene and o-amidobenzoic acid) when heated
with sulphuric acid, or if reduced with tin and hydrochloric acid, a diamido-
derivative being thus produced {Berichte, 8, 1444) : — •

C,h/ =CeH/ I >C,H,(NO,), + H,0.

\cO2H \C(OH)/

Oxydinitro-acridine.

The acridines are feeble bases ; their salts are decomposed by boiling water.
The oxidation of acridine with potassium permanganate affords (through the de-
struction of a benzene nucleus) a/3-quinoline dicarboxylic acid (p. 973).

Acridine has also been obtained from ortho-tolylaniline, CjHj.NH.CjH^.CIIj,
by conducting the vapors through a red-hot tube (analogous to the synthesis of
anthracene) ; by heating diphenylamine with chloroform and zinc chloride to
200°, and when aniline and salicylic aldehyde are heated to 260° with zinc k^\o-
riAt[BeHchte, 12, 2452). It is very soluble in alcohol and ether. It occurs in
crude anthracene and dissolves in dilute acids with a beautiful green fluorescence.
It readily sublimes in colorless leaflets, sublimes at 100°, melts at 1 10°, distils above
360°, and has a very pungent odor.

Dihydroacridine, CgH^^ nh" /'-'6^^4> '^ formed when acridine is reduced

with sodium amalgam or zinc and hydrochloric acid. It no longer manifests basic
properties and melts at 1 68°. Oxidizing agents, even silver nitrate, convert it again
into acridine.

The acridines yield iodides with the alcoholic iodides. Silver oxide or alkalies
convert them into peculiar ammonium bases which are very similar' to the quinoline
compounds (p. 965). Potassium permanganate attacks the pyridine nucleus
present in these alkyl iodide derivatives, forming then phenyl-o.amidobenzoic
acid, CgHj.NH.CsH^.COjH [Berichte, 18, 2709).

»2J-Methyl Acridine, Cj3H3(CH,)N (see above), is formed when diphenyl-
amine and glacial acetic acid are heated together with zinc chloride to 220°. It
consists of colorless plates, melting at 1 14°. Its hydrochloride crystallizes in yellow
leaflets, that dissolve with a bluish-green fluorescence. Chloral and methyl acridine
unite to the compound, Ci3HjN.CH2CH(OH).CClj, which yields acridylacrylic
acid, CijHgN.CH: CH.COjH, when digested with caustic soda. Potassium
permanganate oxidizes this compound to »;j-acridylaldehyde, CjjHjN.CHO,
and ffzj-acridyl carboxylic acid, Cj3HgN(C02H) [Berichte, 20, 1541).

?»i-Phenyl Acridine, Cj3Hj(C5H5)N, results upon heating diphenylamine
and benzoic acid together with zinc chloride to 260°. It crystallizes in yellow
plates (from benzene, with one molecule of benzene), melts at 181° and distils above

i-MISNOXAZINE. 983

400°. Its salts are yellow in color, and are decomposed by water. /-Amido- and
fi-oxy diphenylamine together with benzoic acid yield the corresponding phenyl-
amidoacridine and phenyl oxyacridine [Berichte, 28, 692).

Chrysaniline, CjgHj,N(NH2)2. This is obtained as a by-product in the
rosaniline manufacture. On mixing the mother liquors with nitric acid the nitrate
separates; this is the chief constituent of the beautiful yellow dye phosphine^
Free chrysaniline crystallizes from dilute alcohol in golden yellow needles,
melting about 268°. It forms red colored salts with the acids (i equivalent) ;
these dye silk and wool a beautiful yellow. Their solutions exhibit a beautiful
yellow-green fluorescence.

Chrysaniline has been prepared synthetically by the oxidation of ortholeucaniline
with arsenic acid {^Berichte, 17, 208 ; 18, 696). It is therefore ^-amido-phenyl-

2-amido acridine, HjN.CjH^C^f /N

When chrysaniline is diazotized and boiled with alcohol, it yields ?«i.phenyl-
acridine. If heated to 180° with hydrochloric acid, an amido-group splits off
and Chrysophenol, C]aHji(0H)N.NH2, is produced.

N v.:

Phenyl-/3-naphthyl Acridine, C,oH.<; | ^CuHj, results upon heating

(3-dinaphthylamine, (C,„H,)2NH, and benzoic acid to 240°, together with zinc
chloride. It melts at 297°.

Consult Berichte, 18, 691, upon the nomenclature of the complex acridines.

Thiodiphenylamine (p. 604), diphenylene keton-oxide or xatUhone (p. 860),
and thioxanthone are analogous to acridine in constitution. They all possess a
strong chromogenic character : —

Thiodiphenylamine. Xanthone. Thioxanthone.

Thioxanthone, CijHgSO, is produced in the condensation of diphenylsul-
phide-o-carboxylic acid, C.HjS.CjH^.COjH (from thiophenol and diazoanthranilic
acid, see phenyl sulphide (p. 672), effected by sulphuric acid. It consists of yellow
needles, that become colorless upon distillation. It melts at 207° and boils at
372° (Berichte, 23, 2469).

Phenoxazine, CgH^^^ q ^CgH^, or phenazoxine {i^^ Berichte, 2i,2a%i),

is also analogous to acridine and thiodiphenylamine. It is obtained similarly to
thiodiphenylamine and phenazine (see below), when o-amidophenol is heated to-,
gether with pyrocatechol to 260-280°. It crystallizes from dilute alcohol in leaf-
lets, that melt at 148°, and sublime. In its reactions it is very similar to thiodi-
phenylamine, and it is only in its oxidation product that it shows a chromogenic

984 ORGANIC CHEMISTRY.

character (Nietzki, Berichte, 22, 3036). A reddish-violet dye (Berichte, 20, Q42)
is produced by nitration, reduction of the nitro product with tin and hydrochloric
acid, and again oxidizing with ferric chloride (analogous to the formation of
Lauth's violet from thiodiphenylamine, p. 605).

Resorufin and resazurine, products obtained from resorcinol, appear to be de-
rivatives of phenoxazine (p. 691).

The Oxyindamines and oxindophenoh, so called by Nietzki (Organische Farb-
stoffe, 1889, p. 139; Berichte, 21, 1736), are dyestuffs and appear to be phenoxa-
zine derivatives. They result upon digesting nitroso-dimethyl aniline or quinone
dichlorimide with /3-naphthol. They differ from the indophenols, which are pro-
duced when the reaction occurs at low temperatures, in that the two benzene
nuclei are united a second time by means of oxygen, and hence possess a consti-
tution analogous to that of the thiodiphenylamine derivatives and the eurhodines.
Gallocyanine and naphthol violet belong in this series.

GaUocyanine.CisHi^NjOj (Violet solide von Koechlin), is produced by the
action of nitroso-dimethyl aniline upon gallic acid, catechuic acid, etc. It forms
shining green needles and serves as a beautiful violet-colored lake in calico print-
ing (Berichte, 21, 1740). Naphthol Violet, CjgHjjNjO, of Meldola and Witt,
/3-Naphthol Blue, New Blue, Fast Blue, Cotton Blue, results upon heating nitroso-
dimethyl aniline and /3-naphthol. Its hydrochloride consists of bronze-colored
needles. It dyes cotton, that has been mordanted with tannin, violet blue, similar
to indigo (Berichte, 21, 1744; 23, 2247).

When the free bases of these dyes are heated they become insoluble in ether, and
change to peculiar green-blue dyes that O. Witt has named cyanamines, (Berichte,
23, 2249).

PHENAZINE GROUP.

The simplest parent substance in this group \% phenazine, CijHgNj.
In constitution it is analogous to anthracene and acridine. In it
the two intermediate C-atoms of anthracene are replaced by two
nitrogen atoms : —

CgH^^' I ^CgH., Phenazine.

\]sr/

It contains in addition to the two terminal benzene rings an inter-
mediate ring-chain, consisting of four C-atoms and two nitrogen
atoms ; this is similar to the paradiazine or pyrazine ring. The
constitution and nomenclature of the more complex azines may be
seen from the following arrangement {^Bei-ichte, 20, 23, 327; Anna-
len, 237, 330) :—

/N
C.H,^ ■ •'-•6^4 — Phenazine or Diphenazine.

\n/

^^4^^ . "^CjHj.CHj — Methylphenazine or Toluphenazine.

PHENAZINE GROUP. 985

.N,

CjH^^' . ^CjqHu — Naphthophenazine or Phenonaphthazine.
CgH^'f . pCjjH- — Anthraphenazine or Phenanthrazine.

\n/

C]qH.^ • ^CinHg — Naphthazine or Dinaphthazine, etc.

The following are the most important methods in use for the preparation of the
azines :

1. Condensation of ortho-phenylenediamine (p. 629) with ortho-dioxyberzenes,
'■■<?'■> pyrocatechin, when healed to 200° (Merz and Ris, Jierichte, 19, 726,
2206) : —

.OH HjN. .N,

CeH,/ + >C,H, = CeH / . )CeH, + 2H,0 + H,.

(1,2) — Dioxy- o-Phenylene Phenazine.

benzene diamine.

Pyrocatechine and »«/-toluylene diamine (p. 626), in a similar manner yield
methyl-phenazine or tolu-phenazine (see above).

2. Condensation of the ortho diamines with ortho diketones, or orlhoquinones,
e.g., /3-naphthoquinone — a reaction, perfectly analogous to the formation of the
quinoxalines (p. 979) (Hinsberg, Annalen, 237, 329).

/NH, /N\

C^H^ + Ci„H,0, = C^H, • Ci„H, + 2H,0.

\NH, \N/

(i, 2)— Naphtho- (i, 2) — Naphtho-

quinone, phenazine.

Similarly o-toluylene-diamine yields with phenanthraquinene toluanthrazine,
;3-naphtho-quinone, tolu-naphthazine, with isatine tolu-indazine, C,,H5(N2)C,H5
N, while o-naphthylene diamine and ;3-naphthoquinone yield di-naphthazine, etc.

3. A very convenient method is the conjugation of phenyl — (tolyl, etc.) — /3-naph-
thylamine (p. 911) with diazobenzene sulphonic acids; the diazo group enters the
ortho-position of the naphthylamine and azocompounds result at first: —

Boiling dilute acids change the azo-derivatives to azines and sulphanilic acid
(Witt, Berichte 20, 571) : —

/NH.CeH, /N\

q„He = Ci„H, I CJi, + H,N.CeH,.S03H.

XNiN.C.H^.SOgH. \N/

Naphthophenazine.

4. The oxidation of an orthophenylene diamine, together with /3-naphthol
(Wilt, Berichte, 19, 914; 20, S7S) =—

/NH. /N\

C,H, + Ci„H,.OH + 2 0 = C,K, ■ C,„H, + 3H3O.

\NH2 \N/

Tolu-naphthazine.

986 ORGANIC CHEMISTRY.

The azines are mostly yellow-colored, feebly basic bodies that cannot be distilled
without suffering decomposition. They dissolve in concentrated sulphuric acid
with a red to blue color. They are again precipitated upon addition of water, the
liquid becoming yellow in color in consequence. Ammonium sulphide reduces

them to colorless, dihydro -compounds, CgH^.^'j.j, '^CgH^, which are readily
re-oxidized to azines.

Phenazine, CuHgNj, was first obtained from azo benzoates by distillation,
and was called A^odiphenylene (p. 847). It may also be prepared from ij-pheny-
lene diamine and pyrocatechin, and IJy conducting aniline vapors through a
tube heated to redness [Berichte, ig, 420, 3256). It crystallizes and sublimes in
bright-yellow needles, melting at 171°. It dissolves in concentrated sulphuric
acid with a blood-red color, which becomes yellow upon the addition of water
{BericAte, ig, 2207).

Methyl Phenazine, CjjH,(CH3)N2, Toluphenazine , from pyrocatechol and
o-toliiylene diamine (see above), consists of yellow needles, melting at 117° and
dissolving In dilute acids {Berichie, ig, 726).

Naphthophenazine, C5l-l4(N)2Cj„Hg, may be readily prepared from phenyl
naphthylamine. It forms yellow needles, that melt at 142° and sublime about
200°. It dissolves in concentrated sulphuric acid with a brownish-red color
[Berichte, 20, 573, 2660). Nitro-naphthophenazine, C5H^(N2)Cj„H5(N02),
from nitro-/3-naphthoquinone and o-phenylene diamine, melts at 221° {Berichte, 23,

175)-

Tolu-naphthazines, C,H5(N2)C]oH5. There are four possible isomerides;
three of these are known. Two are produced by the condensation of o-toluylene
diamine with j3-naphthoquinone, and a third has been obtained by the decomposi-
tion of wool-black [Berichte, 20, 577).

Pheno- and Tolu-anthrazine, C5H^(N2)C,4Hg, andCjHg(N2)Ci4Hg, are
easily formed on mixing the warm solution of phenanthraquinone in glacial acetic
acid with the alcoholic solution of o-phenylene and toluylene diamine, when they
separate as yellow needles. The first melts at 217°, the second at 212°. They
dissolve with a deep red color in concentrated acids. Their formation may be used
to detect and separate the orthophenylene diamines (p. 629).

a|8-Naphthazine, CjDH5(N2)Cj(|Hg, Dinaphthazine, formerly called naph-
thase (also thought to be azonaphthalene because it was prepared by heating
nitronaphthalene with lime or zinc dust), results upon mixing o-naphthylene
diamine (i, 2) (p. 626) and /3-naphthoquinone (I, 2). It crystallizes and sublimes
in yellow needles, that melt at 275°- It dissolves with a violet color in concen-
trated sulphuric acid; on adding water the solution assumes a yellow color and
naphthazine again separates {Berichte, 14, 2795).

;3;3-Naphthazine, CjdH5(N2)CioH„, is produced when jS-dinaphtbylamine is
further heated together with benzene diazochloride. It consists of yellow needles
that melt at 242° (^Berichte, 23, 1333).

The phenazines are chromogenic parent substances; they yield dyes by the
entrance of salt-forming groups (especially the amido-group). The eurhodines and
safranines are included in this series.

I. Eurhodines and Toluylene-Red Group.

The eurhodine group consists of dyes, which are derived from the phenazines
by the introduction of one or more araido-groups (Witt, Berichte, 19, 441, 2791 ;
21, 2418; Kehrmann, 23, 2446; Fischer and Hepp, Berichte, 23, 841, 2787).
They are formed : —

EURHODINES AND TOLUYLENE-RED GROUP. 987

(1) By the action of orthoamidoazo compounds (p. 643) upon a-naphthylamine
hydrochloride * : —

.N:N.C,H,

c,h/ +c,„h,.nh, + 0 =

(7-Amido-azo-toluene. a-Naphthylamine.

C^Hex >C,„H5.NH, + C,H,.NH, + H,0.

Eurhodine,

The ortho-amido bodies act similarly with the orthophenylene diamines {Be-
richte, 23, 844, 2787).

(2) By the action of ortho-diamines (as unsymmelrical triamidobenzene, p.
625) upon orthodiketones or orthociuinones : —

H,N.C,H3/^|[^^ + C,„HeO, = H,N.C,H,/ • \c,„H, + 2H,0.

Triamido-benzene. ^-Naphthoquinone. Eurhodine.

Triamido-benzene reads in like manner with phenanthraquinone, benzil,
isatin, and with the diketones of the parafifin series {Berichte, 19, 446). Oxy-
orthoquinones and orthodiamines form oxyeurhodines {^Berichte, 23, 2451).

(3) By the action of nitroso-dimethyl aniline upon primary and secondary anilines
in which the para-position is occupied (as /J-naphthylamine and its phenyl deriva-
tives) (Berichte, 21, 7 1 9) : —

(CH3),N.C,H,.NO -f Ci„H,.NH, + O =

(CH3),N.CeH3/N\c^^H, + 2H,0.

If the j8-naphthyl amine be replaced by its secondary derivatives, the corresponding
azonium bases or safranines will be produced.

Quinone dichlorimide acts just like nitroso-dimethyl aniline ; eurhodines with free
amido groups result {^Berichte, 21, 1599) : —

C1N:C,H,:NC1 + Ci„H,.NH, = H,N.C.H3<^>Ci„H, + 2HCI.

In these methods an indamine always appears at first as a byproduct (Berichte,
21, 2418).

(4) By the oxidation of ortho-phenylene diamines {2, molecules); here the two
nitrogen atoms attack the para-positions, relatively to the two amido-groups, of a
second molecule ; if amid-groups already occupy the para-position, these will be
displaced {S^€Mvasxm, Berichte, 22, 1983; Nietzki, ^mr/^/f, 23, 3039). Thus,
ferric chloride converts o-phenylenediamine into diamiJo phenazine (O. Fischer,
Berichte, 22, 355 ; 23, 841) :—

C6H4<NH^ + CeH,/^^^ + 3O = CeH,<^>c,H,<N^^ + 3H,0.

In the same ■sa&vmcr triamidophenazine\s<ib\.3xaiA from unsymmetrical triamido-
benzene, and tetramidophenazine from symmetrical tetramidobenzene [Berichte, 22,
3039), etc.

*Indulines result by the use of paramidoazo-compounds (p. 990).

p88 ORGANIC CHEMISTRY.

The eurhodines (mono-amido-azines) are feeble bases. Their salts are scarlet
red in color ; they have not been applied technically. They dissolve in concen-
trated sulphuric acid with a carmine-red color, which, upon the addition of water
.passes successively into black, red, and finally red (see safranine). If they be heated
to 1 80° with acids their amido-group is replaced by hydroxyl, with the formation
of phenol-like eurhodols. Compounds like the last, can be synthetically prepared
from oxyorthodiketones by means of orthodiamines [Berickte, 23, 2451).

Amidophenazine, CgH4(Nj)CjH3 NH^, has been prepared from o-diamido
phenazine upon heating it with zinc dust. It consists of red bronze needles, that
melt at 265°.

The toluylene-red compounds, containing two amido-groups, are more important
than the mono-amido-phenazines. They result when diamines are oxidized;
more directly by the oxidation of indoamines having free amido groups, even upon
boiling the aqueous acid solutions. In this way toluylene-blue (from ordinary
»z-toluylene diamine and dimethyl-/-phenylene diamine) yields toluylene-red (Witt,
1887, Berickte, 17, 931 ; 19, 2605; Bernthsen, Annalen, 236, 332) : —

(CH3),N.C,H / I ^CeH,(CH3).NH, + O =

Toluylene Blue,

(CH3),N.C,H3( I >C,H,(CH3).NH, -f H,0.

Toluylene Red.

The so called simplest toluylene-blue (from »2-toluylene diamine and^-phenylene
diamine) thus gives rise to the simplest toluylene-red : —

H.N.C^H,/ I \C,H,(CH3).NH, + O =

Simplest Toluylene Blue.

H,N.C,H3/ I )C,H,(CH3).NH, + H,0.
Simplest Toluylene Red.

Methyl phenazine results by replacing the two amido groups of the latter com-
pound by hydrogen (this is done through the diazo-derivative)-; ordinary toluylene
red yields dimethylamido-methylphenazine when its NHj-group is replaced by
similar treatment. This is proof that the toluylene-red dyes are phenazine deriv-
atives (Bernthsen).

o-Diamidophenazine, C(|H4(Nj)CjH2(NH2)2 (2, 3), formed by the oxida-
tion of tf-phenylene diamine with ferric chloride, consists of ruby-red or yellow-
brown needles [Berichte, 23, 841). (2, 7)-Diamidophenazine, H2N.C„H3(N2)
C^Hj.NHj, is prepared from dinitro-phenyl-/-phenylene diamine, C5H3(N02)2 —
NH.CgH^.NH 2, and consists of dark yellow needles, melting at 280°. Tetra-
amidophenazine, (H2N)2C5H2(N2)CjH2(NH2)j, from tetra-amidobenzene
with ferric chloride, consists of brown-colored needles and decomposes about

130°.

Toluylene Red, Cj^Hn-N^, Dimethyl diamido-toluphenazine (see above),
crystallizes in orange-red needles. It is applied in dyeing under the name Neutral
Red. Its monacid salts are rose-red in color, the diacid blue, and the triacid
green ; the last two are only stable in the presence of strong acids. It colors silk
and cotton, mordanted with tannin, a scarlet- red.

SAFRANINES. 989

2. Safranines.

The safranines are probably diamido derivatives of hypothetical
phenyl-phenazonium ; their ammonium salts are dyestuffs (Witt,
Nietzki, Bernthsen, Berichte, 20, 19, 179; ig, 3121, 3163; 21,
1590):—

CeH / I )C„H, C,H / | )C,H3.NH,

/\ /\

CI C.H^ CI C.K^.NH,.

Phenyl-phenazonium Chloride. Phenosafranine Hydrochloride.

The only known analogue of hypothetical phenyl-phenazonium
(without side groups) has been prepared from amidophenyl-a-
naphthylamine and phenanthraquinone {Berichte, 20, 1183).

The safranines are produced upon oxidizing a mixture of an in-
doamine and a primary amine (this takes place when their salts are
boiled with water). Thus, phenylene blue and aniline y\t\6. pheno-
safranine : —

HN.CeH, H,N ,N

I '■^^ N

■^ / \

CjH^.NH,, Cr XgH^.NHj

Phenylene Blue. Phenosafranine Hydrochloride.

A simpler procedure consists in applying the components of the indamines, and
directly oxidizing the mixture of one molecule of a /-phenylene diamine with one
molecule of a monoamine and a molecule of a primary amine (by boiling the
aqueous solution of their sulphates alone or with chromic acid) ; an indoamine
results at first, and this then combines with the primary amine to produce the sa-
franine [Berickle, 21, Ref. 248) ; —

HjN N

K,N.CeH5 \ ^^H ^ jj^,, ^ ^Q^ ^ J, ^j^ ^^ jj / j \c^H, 4-4H,0.

Monamine. \ ] /

HjN N

I / \

CeH^.NH, CI C,H,.NH,

Diamine. Safranine Hydrochloride.

The furmation of the safranine only occurs by this procedure, provided there is
a free NHj-group in the phenylene diamine, if the para-position in the first mon-
amine and the ortho in the second primary amine are unoccupied [Berichte, 19,
3165). Technically the mixture of the diamine and monamine is obtained by the
reduction of amido azocompounds (p. 644).

The safranines are strong bases. They form salts with one, two and three
equivalents of the acid ; water decomposes the last two series. The monacid salts
are reddish-yellow, the diacid blue, and the triacid green in color. The addition
of water to the green solution of the safranines in concentrated sulphuric acid
causes the same to change to blue, violet and finally red ; while the addition of
concentrated hydrochloric or sulphuric acid to the reddish-yellow aqueous solution

990 ORGANIC CHEMISTRY.

of the primary salts causes the same to pass successively into violet, blue, d«rk
green and eventually light green. The alcoholic solutions usually, exhibit a
strong yellowish-red fluorescence. The difficult solubility of their nitrates is note-
worthy. Reducing agents convert safranines into leuco-compounds, which in the
presence of alkalies are rapidly reoxidized by the air to safranines. The free
safranine bases or hydroxides are separated from their ammonium salts with diffi-
culty (when warmed with caustic alkalies), and generally show a red color.

The lowest member of the safranines is

Phenosafranine, CjgHijN^Cl, formed from /-phenylene diamine and
aniline. It consists of needles, green in color and having a metallic lustre. It dis-
solves in water and alcohol with a beautiful red color. Baryta separates the free
base, CjjHjgN^O, from its sulphate; an excess of baryta will substitute two
hydroxyls for the two amido groups, producing their safranol, CjgHjjN2(0H)j
(Berichte, 21, 1591).

Ethyl- and Methyl Safranine, CjgH„(CH3)NjCl, can exist in two isomeric
forms (corresponding to their constitution and different components). Dimethyl-
and Diethyl Safranine, ^^Yi.^{Cii.^^fi\. Each of these bodies may occur in
three isomeric forms {Berichte, ig, 150, 3164).

Tetra-ethyl Safranine, CjgHjj(C2H5)4N^Cl. There is but one possible
modification of this compound. It is formed from diethyl-^-phenylenediamine
with diethyl aniline and aniline. It dyes violet and formerly was applied as
amethyst.

Tolu-Safranine, CjjHj3(CHg)2N.(Cl, from toluylene diamine, »-toluidine (l
molecule) and aniline (l molecule), is the chief constituent of common safranine,
occurring in commerce as a brown paste or yellow-red powder, employed in cotton
and silk dyeing, as a substitute for safflor. The necessary base-mixture for its
production is obtained from the "aniline oil for safranine." Tliis is partially
diazotized and the product broken up into paratoluylene diamine and orthotoluidine
by reduction. •-

The benzidine-tetrazo-dyes have in recent years largely replaced the safranine
dye-comp'ounds. A violet dye, Phenylsafranine, C2oHij(CgH5)N^Cl or Cj,
H2o(*--6H5)N^Cl, is probably identical with Mauveine (Mauvaniline). The latter
was the first aniline dye to prove valuable technically (Perkin, 1856), and is
obtained by oxidizing aniline oil with potassium bichromate and sulphuric acid.
Its sulphate is known in commerce under the name Rosolan.

Naphthalene Red, Magdala Red, C35H2iNiCl, is a safranine of naphtha-
lene. It very probably is a diamido-derivative of a naphthyl-naphthazonium salt,
Ci(|Hg(N2)C,(|Hj(CiDHj)Cl Clv&as,, Berichte, 19, 1365). It is produced when
a-amido-azonaphthalene (p. 914) is heated together with naphthylamine acetate.
It is a dark brown powder, that dissolves very readily in alcohol with a bluish-red
coloration ; the dilute solution exhibits a magnificent cinnabar-red fluorescence.
It imparts a beautiful rose red color to silk. Its alfoholic solution is decolorized
when boiled with zinc dust, but again assumes a red color on exposure to the air.

The indulines and nigrosines appear to belong to the safranine class. They are
violet-blue to gray-blue dyes. They are formed upon heating various azo- and
amido-azobenzenes with aniline hydrochlorides. The simplest induline is Azophenyl
Blue or Violaniline, Cj^Hj^Ng (Induline B), which forms upon heating nitro-
benzene, aniline, hydrochloric acid and iron filings (Coupler's method), or amido-
azobenzene with aniline hydrochloride (Caro) : —

C,H,.N2.C,H,.NH2 + C,H,.NH2.HCl = Cj3Hi5N3 -f NH^Cl.

ALKALOIDS. 991

Here, as in analogous reactions, the first product is azophenine, CjjHj^N^,
which represents a dianilido quinone dianilide (p. 700). The indulines resuit by
the continued action of the azophenine upon anilines. They are also prepared by
heating together nitroso-diphenylamine and the amine hydrochlori'des. Hence,
the indulines are anilido-anilide derivatives of the phenazines (Witt, Berichte,
20,2659; O. Fischer and Hepp, ^?nV/i/^, 20, 2479; 21, 2617). The induline
salts are usually insoluble in water. The easily solulile sulpho- acids have been
used in silk dyeing as substitutes for indigo.

The rosindulines are peculiar red dyes formed upon heating nitrosophenyl- or
nitrosoethyl-anaphthylamine, C](|H,.N(N0).CjH5, with the HCl-anilines, and
by heating benzene azo-a-naphthylamines with anilines [Berichte, 21, 2631 ; 23,
Ref. 391).

Fluorindenes, closely allied to the indulines and azophenine, are produced by
the protracted heating of azophenine or amidophenazines alone or with ortho-
diamines. They dissolve in alcohol with beautiful fluorescence and form greenish-
blue colored fluorescent salts {^Berichte, 23, 2789).

Aniline Black, CjgHjjNj or C3|,H2,N5(?), most probably belongs to the indu-
lines, and is formed in the oxidation of aniline by means of potassium chlorate in
the presence of copper or vanadium salts. It is a dark-green amorphous powder,
insoluble in the ordinary reagents. It is used in calico printing as a black color,
its formation being first effected upon the fibre of the material.

Naturally occurring compounds, the constitution and synthesis of
which have not been definitely established, will be discussed in
special groups in the remaining pages.

ALKALOIDS.

By this term we know all nitrogenous vegetable compounds of
basic character, or their derivatives, from which bases may be
isolated. Many of them (betaine, asparagine, thelne), have, in
accord with their constitution, been already discussed with the
various amido-derivatives ; the most of those remaining which have
been studied recently, show themselves to be derivatives of the
pyridine and quinoline bases. Several have been prepared artificially
(piperidine, conine). Only the most important members of this
insufficiently investigated class will be mentioned here. Like the
benzene derivatives they have much in common in their whole
deportment. They are the chief constituents of the active principles
of the vegetable drugs employed as medicines or poisons.

Some alkaloids contain no oxygen, and then are generally liquid
and volatile. Most of them do, however, contain that element,
and are solid and non-volatile. Nearly all are tertiary amines ;
some, however (like the hydrides of the pyridine nucletis, p. 936),

992

ORGANIC CHEMISTRY.

belong to the secondary amines. Tannic acid, phospho-molybdic
acid, platinic chloride, and many double salts (like Hgl.aKI)
precipitate all these bases from their aqueous solutions. The bases
are regained from these compounds by alkalies.

Sparteine, CuHj^Nj, is a volatile alkaloid which does not contain oxygen.
It occurs in Spartium scoparium, and is a colorless, thick oil, boiling at 311°. It
has a strong alkaline reaction, is narcotic and is also a diacid base. A methyl
group is eliminated when it is heated with hydrochloric or hydriodic acid. It
forms j)/-methyl pyridine when distilled with lime [Berichte, 21, 825). Hence,
sparteine is closely allied to dipicolyl methane, CH2(CH.C5HjN)2 (from methylal
and picoline) (Berichte, 21, 3103).

Opium Bases.

In opium, the dried juice of the green seed capsules of poppy
(Papaver somniferum) we find not only meconic acid and meconine
(p. 794) but a series of bases, of which may be mentioned : —

Morphine, Ci^HjgNOj Papaverine, CjoH^iNO^

Codeine, CigH^iNOj Narcotine, C^zHjjNO,

Thebaine, Cjjlli'jjNOj Narceine, CjjHjgNOg.

Morphine, CnHigNOs -f H2O, crystallizes from alcohol in
prisms, tastes bitter, and in small quantities produces sleep. It
shows an alkaline reaction, and represents a tertiary, monacid base.
Its officinal hydrochloride, C17H19NO3HCI + 4HsO, forms delicate,
silky needles.

The solutions of morphine and its salts are colored dark blue by ferric chloride;
the solution in concentrated sulphuric acid acquires a blood-red coloration on the
addition of a little nitric acid. It contains two hydroxyl groups, Cj,H],(OH)2NO,
deports itself as a dihydric phenol, dissolves in potassium hydroxide, and yields
alkyl and acid derivatives. It forms quinoline, phenanthrene (with phenanthrene-
quinoline) pyridine and pyrrol, on distillation with zinc dust. When methylated to
its fullest extent, morphine undergoes a rearrangement similar to that of piperidine
and Conine (p. 950). The hydroxide obtained from ethyl morphine by addition
of methyl iodide and the action of silver oxide, passes into the phenanthrene de-
rivative {Annalen, 222, 235) on the application of heat. The nitrogen atom
splits off in the form of dimethylamine or oxyethyl dimethylamine (CHj)jN.CH2.
CH2(0H). The latter is related to morpholine (pp. 957, 981), hence morphine
appears to represent a phenanthrene-morpholine derivative (Knorr, Berichte, 22,
1 1 13; 22, Ref. 758).

Codeine, CijHjiNOj, Methyl Morphine, Ci,Hj,( q^tt ) NO, is con-
tained in opium, and is obtained from morphine by means of methyl iodide and
potassium hydroxide. From ether it crystallizes in large prisms, melting at 150°
{Berichte, 19, 794).

Thebaine, Ci <,H23N03 = Ci5Hi,(0 CH3)jN0, consists of silvery plates, melt-
ing at 193°. It breaks down into 2CH3CI and morphothebaine, when heated
with concentrated hydrochloric acid. This new isomeric base melts at 180°.

HYDRASTINE. 993

Silver oxide converts its methyl iodide derivative into an ammonium hydroxide,
which breaks down quite readily on the application of heat {Berichte, 19,
794)-

Papaverine, CjuHjjNO^ [Berichte, \%, Ref. 636), consists of colorless prisms
melting at 148°. It very probably is a tetramethoxyl derivative of benzylisoquino-
line (Goldschmidt, Berichte, 20, 623; 21, Ref. 653; Roser, Annalen, 254,
357) :—

CsH3(O.CH3)2.CH2.CgH4(O.CH3)jN = Papaverine.

Hot hydriodic acid decomposes it into 4CH3I and the base pafaveroline, CjjHg
{0H)4N. Potassium permanganate oxidizes it to papaveraldine, CjoHjgNOj,
which in all probability is a ketone, CeH3(O.CH3).^.CO.CgH^(O.CH3)2N.

Further oxidation gives rise to two decompositions, (l) that of the benzene
nucleus whereby dimethoxy-cinchoninic acid, CgH4(O.CH3)2N.C02H and a/Jy-
pyridine tricarboxylic acid are produced ; (2) that of the isoquinoline nucleus,
resulting in formation of veratric acid and metahemipinic acid (p. 794) [Berichte,
21, Ref. 787). Papaverine breaks down inio veratric acid and dimethyl isoquino-
line when fused with caustic potash. Consult Berichte, 22, 102, 755, for papave-
rine ammonium bases.

Narcotine, Cj^HjjNO,, is separated from morphine by potassium hydroxide, in
which it is insoluble. It crystallizes from alcohol m shining prisms, and melts at
176°. In constitution it is intimately related to papaverine. It contains not only
the benzene, but also the isoquinoline nucleus. It very likely represents a
meconine-hydrocoiarnine (Roser, Berichte, 23, Ref 16, 19; Annalen, 254,
357) :—

.CO.O
qH2(OCH3)/ /

\cH—CuHi403N(CH3) = Narcotine.

Meconine-hydrocotarnine.
1
When toiled with water narcotine is decomposed into meconine, CiqHjjO^ (p.
794), and cotarnine, C12H13NO3.H2O. The latter appears to be an aldehyde
with an open pyridine chain, which in the cotarnine salts and hydro-cotarniue is
closed up as a pyridine ring (and isoquinoline ring) (Berichte, 22, Ref. 27) : —

.CHO.NH.CH3 CH2.N.CH3

' ' '\CH2-CH2 '\CH2.CH2

Cotarnine. Hydrocotarnine.

Potassium permanganate oxidizes cotarnine or cotarnone to cotarnic acid,
CH /'5>CH„ ^ :^^S^^ , which can be further changed to methyl methylene

gallic acid, CeH^ (C>CH2) (go^^'ll^', and gallic acid, C,H2(OH)3.CO,H.
Narceine, CjgH^gNOs (see above), appears to be a naphthalene derivative

{Berichte, 21, Ref. 249).
A compound allied to papaverine and narcotme is . , , , . ^ ^^ ^^^^
Hydrastine, C^iH^NOe, which occurs together with berbenne, Q^^^^^O^

-f- i,yi,\lfi, in the roots of Hydrastis canadensis [Berichte, 23, 404, 2897).

83

994 ORGANIC CHEMISTRY.

Cinchona Bases.

The cinchona barks contain, in addition to tannin and quinic
acid (p. 785), a series of bases, the most important of which are :

Quinine, C25H24N2O2, Conquinine, C20H24N2O2,

Cinchonlne, C19H22N2O, Cinchonidine, Cj5|H22N20.*

Quinine and cinchonine are present in large quantity in so-called
Calisaya bark, while the bases conquinine or quinidine and cin-
chonidine, isomeric with them, predominate in other varieties of
quinia barks.

Quinine, CjoH^^NjOa, is found as high as 2-3 per cent, in the
yellow Calisaya bark. It crystallizes with 3H2O in prisms, or when
anhydrous (from alcohol and ether) in silky needles, melting at
177°. It reacts alkaline, tastes bitter, and being a diacid base forms
primary and secondary salts.

The neutral sulphate, (C2|,H2^N202)2H2SO^ -|- SHjO, and the primary
hydrochloride, C2„H24N202.HC1 + ^HjO, are employed in medicine. The
former consists of long, shining needles, which fall to a white powder on exposure.
It dissolves readily in dilute sulphuric acid, the solution exhibiting a beautiful blue
fluorescence.

When chlorine water and then ammonia are added to the solution of a quinine
salt, there is produced a green precipitate, dissolving in an excess of ammonium
hydroxide with an emerald-green color. On adding ah alcoholic iodine solution
to the sulphate in acetic acid, &periodide, called herapathite, is precipitated. This
crystallizes in emerald-green plates with golden lustre, and polarizes light (he same
as tourmaline.

Quinine is a tertiary diamine, and with metallic iodide| yields
the iodides, CjoH.^N.Oj.CHal and C2oH24N202.2CH3l. The first of
these yields the so-called methyl quinine, C2oH2ij(CH3)N202, when
it is boiled with caustic potash.

Cinchonine, C19H22N2O, occurs principally in the gray quinia
bark (Chitia Huanaco) (upwards of 2.5 per cent.) It crystallizes
from alcohol in white prisms, sublimes in needles in a current of
hydrogen, and melts about 250°. Like quinine it seems to dissi-
pate fever, but to a less degree.

Quinine and cinchonine contain one hydroxyl, and the former an additional
methoxyl group : ^

Q,H2,(OH)N2 Ci9H2„(O.CH3)(OH)N2.

Cinchonine. Quinine.

They yield acetyl derivatives when heated with acetic anhydride. Quinine

* The quinoidine of commerce generally consists of cinchonidine and sometimes
of conquinine.

BRUCINE. 995

heated to 150° with hydrochloric acid splits off the methyl group, with formation
of apoquinine, CjgH2o(OH)2N2, which deports itself like a bivalent phenol.
Phosphorus pentachloride converts cinchonine (by replacing its hydroxyl group)
into cinchonine chloride, CigHgiClNj, quinine into quinine chloride, C^oH^g-
CIN2O, and these compounds boiled with alcoholic potash yield cinchene and
quinene : —

C19H20N2 and C20H22N2O,
Cinchene, Quinene.

which, when heated to 190° together with concentrated hydrochloric or hydro-
bromic acid, give up ammonia and absorb water, thus forming apocinchene and
apoquinene : —

Cj<,H,,NO C2„H.,iN02.

Apocinchene. Apoquinene.

Apocinchene manifests a phenol character, and may be considered a 7-phenol-
quinoline, CgHjN.CgH^.OH (p. 971), in the benzene nucleus of which alkyls are
yet present, C9HsN.CgH2(C^Hio)OH or CaH^N.CioHij.OH. It is not known in
what manner the second N-atom in cinchonine is combined with the side-chain
(Koenigs, Berickte, 20, 2688, 2526, 2669) (see also Skraup, ^^?-;V;4fe, 22, Ref.

332,578).

Oxidation converts cinchonine into cinchoninic acid (y-quinoline carboxylic
acid, p. 972), whereas quinine yields quininic acid, (methoxy y-quinoline carboxylic
acid, C9H5(O.CHj)N.CO,;H, p. 973). More energetic oxidation, with potassium
permanganate, changes cinchonine and quinine into a/Sy-pyridine tricarboxylic acid
and cinchomeronic acid (p, 948), If cinchonine be fused with alkalies it forms
quinoline, CgH^N (together with /?ethyl pyridine and fatty adds), but from
quinine under like treatment we get a methyloxyquinoline, CgHg(0.CH3)N
(p, 969),

Bases from Strychnos.

In the fruit of the different strychnos, principally in that of
Strychnos nux vomica and in St. Ignatius' bean (Strychnos Igna-
tii), are found two very poisonous bases : Strychnine and brucine.

Strychnine, CjiHj^NjOj, crystallizes in four-sided prisms, melting at 284°,
reacting alkaline and possessing an extremely bitter taste. It is a tertiary amine,
and when fused with potassium hydroxide yields quinoline and indol. Consult
Berichte, 23, 2721, upon the methyl strychnines.

Brucine, CjaHjeNjO^,, crystallizes, containing four molecules of water, in
prisms, and melts at 178° when anhydrous. It dissolves with a red color in con-
centrated nitric acid. On application of heat it becomes yellow and violet after
the addition of stannous chloride. When distilled with potassium hydroxide it
yields /3-etbyl pyridine and two coUidines.

Strychnine and brucine probably contain a quinoline nucleus ; in strychnine
there is also present a phenylpyridine, and in brucine a dioxymethyl phenylpyri-
dine [Berichte, 21, 451, 813).

Solatium Bases.

In some varieties of Solanum there are found three isomeric al-
kaloids of very similar constitution, ChH^sNO,. They are atropine,
hyoscyamine and hyoscine. If they are introduced in very small

996 ORGANIC CHEMISTRY.

quantity into the eye they cause dilatation of the pupil and are
therefore employed in the treatment of the eyes. All three decom-
pose into tropic acid (and atropic acid, p. 813), and a base,
CgHijNO, when heated with hydrochloric acid or baryta water: —

Ci,H,3N03 + H^O = CsHijNO + C^HioOj ;

by this reaction tropine is formed from atropine and hyoscyamine,
but from hyoscine we get isomeric pseudotropine. By the same
treatment dextro-tropic acid yields dextro -atropine and Isevo-tropic
acid Isevo-atropine (Berichte, 22, 2591). Conversely, inactive atro-
pine is again recovered by evaporating tropic acid and atropine with
dilute hydrochloric acid.

Atropine, daturine, CjyHjjNOj, is prepared from the deadly nightshade
(Atiopa belladonna) and Datura strammonium by a rearrangement of the hyos-
cyamine present in them {Berichte, zi, 1719). It crystallizes from alcohol in
small prisms, melting at 114°. It is optically inactive. Dextro-atropine., from
dextro-tropic acid, forms while shining needles, melting at 110-111°; Icevo-atropine
is a crystalline powder, that melts at 111°. It is similar to hyoscyamine, but not
identical with it. The supposed rearrangement of atropine into hyoscyamine (Be-
richte, 21, 1717, 2777) is due, according to Ladenburg, to the presence of consid-
erable hyoscyamine in the atropine (^Berichte, 21, 3069).

Hyoscyamine, CjjHjsNOj, occurs in the seeds of Hyoscyattius niger,m
Atropa belladonna and in Datura stravmionium^ It crystallizes fiom chloro-
form in shining needles, and melts at 108.5°. Hyoscine, CijHj.jNOj, is a
viscous liquid found in henbane.

Duboisine, from Duboisia myoporoides, is either hyoscyamine or hyoscine
(^Berichte, 20, 1661).

Belladonine, Cj,H23N03, resembles these alkaloids. It occurs with atropine,
and is likewise decomposed into tropic acid and oxy-tropine, CgHjjNOj {^Berichte,
17, 152, 383)-

Just as tropine yields atropine with atropic acid, so it is capable
of entering combination with other acids producing ester-like deri-
vatives, which have been called tropetnes (Ladenburg, Annalen, 217,
82). Of these phenylglycolyl-tropeine or Homatropine, CgHiN
(CH3).C2H,.O.CO.CH(OH).C6H5, is noteworthy. It is obtained
from tropine and mandelic acid. It is employed as a substitute for
atropine, and is applied in the form of hydrobromide.

Cocaine, C^HjiNOi, is present in the leaves of Erythroxylon
coca. It crystallizes in colorless prisms, melting at 98°. It is a
very superior local anaesthetic and is applied in the form of hydro-
chloride. When it is digested with hydrochloric acid it breaks
down into ecgonine, C9H]5N03, benzoic acid and methyl alco-
hol :—

q,H,iNO, + 2H,0 = CgHi^NOj + C,II„0, -f CH3.OH.

ECGONINE. 997

It yields benzoyl ecgonine, C9Hi4(C,H50)N03, when boiled with
water. Cocaine is, therefore, a methylated benzoylecgonine (see
below).

Conversely, cocaine can be again re-formed from ecgonine by heating it together
with benzoic anhydride and methyl iodide, or from benzoyl ecgonine with methyl
iodide and sodium ethylate (Merck, Berichte, i8, 2953). It is more readily
obtained by the etherification of benzoyl ecgonine with methyl alcohol and hydro-
chloric acid (Einhorn, Berichte, 21, 47), or by introducing IJenzoyl into ecgonine
ester (Berichte, 21, 3202, 3336). This procedure is used at present in its piepara-
tion on a large scale.

Crude cocaine, obtained by extracting coca-leaves, contains a series of amorph-
ous alkaloids (cocamine, hygrine, Berichte, 21, 665, 675), from which it is sepa-
rated with great difficulty. These associated alkaloids are also derivatives of
ecgonine, and contain isatropic acid (isatropyl cocaine), truxillic acid and isocinna-
mic acid (p. 812) instead of benzoic acid. All eliminate ecgonine when digested
with hydrochloric acid (Liebermann, Berichte, 21, 3196), and from this the pure
cocaine is prepared synthetically.

Ordmary cocaine is laevo-rotatory. Dextro-Cocaine (Berichte, 23, 508, 926)
occurs with it in slight amount. The latter is obtained pure from dextro-ecgonine
(Berichte, 23, 468, 982). It forms prismatic crystals, melting at 43-45°.

Ecgonine, CgHjjNOg -)- H^O, produced in the decomposition of cocaine, is
very soluble in water, more sparingly in alcohol, and consists of prismatic crystals
that melt at 205° (at 140° when dry). Its esters are formed when hydrochloric
acid gas is conducted into its alcoholic solution (Berichte, 21, 3336). Benzoic
anhydride acting on aqueous ecgonine (Berichte, 21, 3198, 3372) produces
Benzoyl Ecgonine, C8Hi^(C,H50)N03 -f- 4H2O.

In the anhydrous state this melts at 195°- Ecgonine is Icevo-rotatory. It passes
into the dextro variety when digested with caustic potash. The latter melts at 254°
(Berichte, 23, 470, 979), and yields dextro- cocaine.

The withdrawal of water from ecgonine (by boiling with POCI3) produces an-
hydroecgonine, CgB-^^^O^, melting at 235° (Berichte, 20, 1221). This is an
unsaturated acid, which potassium permanganate converts into the oxyacid,
ecgonine. a-Ethyl pyridine results upon distilling ecgonine with lime or zinc
dust (Berichte, 22, 1126, 1362). The preceding compounds, therefore, are deri-
vatives of »-methyl tetrahydropyridine, in which one of the side groups is in the a-
position (Einhorn, Berichte, 20, 1228). Ecgonine is n-methyl-tetrahydropyridine-
^-oxy-propionic acid : —

C5Hi(H3)N(CH3).CH(OH).CH2.C02H = Ecgonine;
anhydroecgonine is the corresponding acrylic acid : —

C5H4(H3)N(CH3).CH : CH.CO^H = Anhydroecgonine,
and cocaine is the benzoyl-ecgonine-methyl ester: —

C5H,(H3)NCH3.CH(O.C,H50).CH2.C02.CH3 = Cocaine.

Anhydroecgonine is the tetrahydro-»-methyl derivative of the pyridylacrylic
acid (p. 947), ecgonine, the derivative of pyridyl-/3-lactic acid (Berichte, 23,
224). Tropidine is obtained from anhydroecgonine by heating the latter with
hydrochloric acid to 280°, when it loses carbon dioxide {Berichte, 23, 1338).
Potassium permanganate oxidizes ecgonine to tropic acid, CgHijNO^ (Berichte,
23, 2518, 2889).

998 ORGANIC CHEMISTRY.

There remain other alkaloids which have been poorly investigated: mention may
be made of the following : —

Veratrine, Cj^H^gNOg, Cevadine. This occurs, together with veratric acid
(p. 779), and other alkaloids, in the white hellebore (from V. album) and in the
Sabadilla seeds (from V. Sabadilla). It crystallizes from alcohol in prisms, and
melts at 205°. It dissolves in sulphuric acid with a yellow color, which gradu-
ally changes to blood-red. It yields j3-picoline [Berichte, 23, 2707) by dry dis-
tillation.

Sinapine, CjjHjjNOj, occurs as sulphocyanate in white mustard. Free
sinapine is very soluble, and decomposable. When boiled with alkalies it decom-
poses into choline and sinapic acid, CjjHjjOj, which is a butylene gallic acid.

TERPENES.

The terpenes are hydrocarbons, analogous to turpentine oil.
They have the formula CioHu or (CsHg)^, and are contained in the
volatile or ethereal o\[s obtained in the distillation of various plants
(chiefly Coniferse and Citrus species). The terpenes that have been
thus isolated are very numerous; their properties vary but little, and
they have heretofore been considered either as chemical or physical
isomerides, according to their origin. In recent years investigators
have succeeded in reducing them to a few (8-10) pure parent-
substances, and referring them to individual groups. Their dis-
tinction and classification depends upon the power that some pos-
sess, of combining with one or two molecules of bromine or a halo-
gen hydride, or with nitrosyl chloride (with two or four affinities),
whereas others are incapable of forming addition products (see
Wallach, Annalen, 230, 225 ; 239, i ; 245, 241 ; 252, 106, etc.).

The addition of the halogens or halogen hydrides succeeds best in a glacial acetic

acid solution at low temperatures. The additive products revert to the terpenes

when heated with sodium acetate (in glacial acetic acid solution).

-'CI
The nitroso-chlorides oi ihe terpenes, C,„Hjg;f ^j-, (p. 112), were first obtained

by the action of nitrosyl chloride, NOCl, upon the pinenes and limonenes (Tilden).
A simpler method for their preparation consists in shaking a chilled mixture of
terpene and amyl nitrite (or ethyl nitrite) with concentrated hydrochloric acid,
and then adding alcohol or glacial acetic acid (Wallach, Berichte, 21, Ref. 622;
22, Ref. 583). The nitroso-chlorides are crystalline compounds, which melt above
100°. They form nitrolamines with organic bases (amines, anilines, piperidines)
(they thus resemble the niirosates of the alkylenes, (p. II2) [Berichte, 21, Ref.
584) :-

CioHi6\ci + N^a-CeH,, = CioHis<^.|^jj^^jj^ -j- HCl.

The elimination of hydrogen chloride in this reaction, which occurs with some
bases, leads to the formation of Nitroso-terpenes, Cj gHj 5(N0).

Several terpenes (as the dipentenes) unite with NjO^ and form niirosates Cg

PINENE AND CAMPHENE GROUP. 999

H4(NO).O.N02 (p. H2). Terpinene and phillandrene yield nitrosiUs, C ^H ^
(N0)(0.N02) with N2O3.

The terpenes are closely related, so far as constitution is con-^
cerned, to ordinary cymene, QoHn (/-methylpropyl benzene, C3H,.
CeHj-CHs) ; they can be readily converted into it by the withdrawal
of two hydrogen atoms (see below and p. 577). This occurs by
their oxidation to /-toluic and terephthalic acids, C6H4(C02H)2.
Therefore, the terpenes may be viewed as benzene additive pro-
ducts— as dihydrocymenes, CioHi4(H2).

In accordance with the generally accepted structure of the benzene nucleus
several /-dihydrocymenes are possible; they contain in addition two divalent
ethylene unions, and therefore can form additive products with four affinities (p. 567)
(Compare cilrene). Again, there are other terpenes which contain but two free
affinities, or are not capable of forming additive products (pinene, camphene, etc.).
These very probably originate from differently constituted benzene nuclei with
diagonal or para-linkages (p. 564)' This seems evident from their lower refractive
power (Briihl, Berichte, 21, 145, 467). Wallach considers that the conclusions
drawn from the molecular refractions are unreliable (Berichte, 21, Ref. 342; 22,
Ref. 584).

(i) PINENE AND CAMPHENE GROUP.

These combine with but one molecule of the halogen hydrides.
The first forms a compound with nitroso-chloride, the second does
not.

(i) Pinene — Ci„Hi6 — is the chief ingredient of the turpentine
oil prepared from the different varieties of pine, of eucalyptus oil,
juniper-berry oil, sage oil, etc.

The resinous juice, called turpentine, exuding from various corii-
ferse, consists of a solution of resin in turpentine oil, which distils
with steam while the resin (colophony) remains behind.

Oil of turpentine is a colorless peculiar-smelling liquid, boiling
from 158-160° ; its sp. gr. equals 0.856-0.87. It is almost insoluble
in water, is miscible with absolute alcohol and ether, dissolves
sulphur, phosphorus, resins, caoutchouc, and, therefore, serves for
the preparation of oil colors and varnishes.

The turpentines, according to their origin, show some differences, especially in
their optical rotatory power.

The German turpentine oil (from Pinus silvestris and Abies excelsa), the French
(from Pinus maritima), called Terebenthene, the Venetian (from Larix eurofaa),
are Isevo-rotatory, while the English (from Pinus australis) called Australene, is
dextro-rolatory. This is also true of the terpene from oil of wormwood, and from
the oil of mint. , _ .

The basis of these various turpentine oils seems to be a Dextro-pmene and a

lOOO ORGANIC CHEMISTRY.

lavo-pinene (as in the case of the tartaric acids). The Russian and Swedish tur-
pentine oils consist mainly of cinene and sylvestrene (see below),

Oil of turpentine slowly acquires oxygen from the air (with ozone formation)
and resinifies with production of acids (lorraic, acetic); at the same lime small-
quantities of cymene are formed. When tprpenline is boiled with nitric acid,
different falty acids, terebinic acid, pyrocinchonic acid, toluic acid and terephthalic
acid result. Chromic acid converts it into terebinic acid and terpenylic acid
(p. 470).

Turpentine oil (pinene) heated to 250-300" is converted into dipentene, CjqHjj
(see below) and meta-terebenthene, C^jHjj (boiling at 260°). Turpentine oil
heated together with iodine in a vessel in connection with a return cooler under-
goes a violent reaction and forms cymene, Cj„Hjj. The same compound is pro-
duced on heating the dichloride, Cj^Hj^Cl,, when it loses two molecules of
hydrogen chloride. Terpene Tetrahydride, CjqHj,,, is produced when tur-
pentine oil is heated with hydriodic acid or phosphonium iodide. It boils at
170-172°. Menthene is a dihydride, Cj,Hjg (p. 1007).

Pinene unites with a molecule of chlorine and bromine, forming
liquid compounds that are not very characteristic. In the same
manner it combines with but one molecule of hydrochloric or
hydrobroraic acid — -the products being solids, which cannot absorb
additional halogens or halogen hydrides. It is therefore very
probable that pinene contains but one divalent union (see above).

Pinene Dichloride, CioHuClj, and Pinene Dibromide,
CmHieBrj, are unstable liquids. When heated they break down
into halogen hydrides and cymene.

Pinene Hydrochloride, CjuHjg.HCl, is produced on conducting HCl gas
into well-cooled pinene. The hydrochloride (called artificial camphor) yields
crystals resembling those of camphor, has the odor of the latter, melts at 125°, and
boils at 208°. Tlie hydrochloride of lasvo-pinene is Isevo-rotatory, while that from
dextro-pinene is dextro-rotatory. Pinene Hydrobromide, Cj„Hj,Br, formed like
the hydrochloride, melts at 90° and has a higher boiling point than the chloride.

Solid camphene (see below) results when the preceding compounds lose hydro-
gen chloride or bromide. This occurs when they are boiled with glacial acetic
acid and sodium acetate.

Pinene Nitroso-chlojide, Ci|,Hjg(NO)Cl, obtained by means of nitrosyl-
chloride, or amyl nitrite, glacial acetic acid and hydrochloric acid, melts at 103°;
the bromide, C,pHjg(NO)Br, at 92°- Piperidine and the chloride yield Nitro-
lamine, Cj|,Hj8(NO).NC5Hj(|, but with other bases the product is Nitrosoter-
fene, CidHi5(N0), melting at 132°.

By the prolonged action of moist hydrogen chloride upon pinene, the latter re-
arranges itself to dipentene, a dihydrochloride, C^dHj jClj, that melts at 50°, and
is identical with dipentene-dihydrochloride (see below).

If turpentine oil containing water be permitted to stand for some time with nitric
acid and alcohol (Annalen, 230, 248), or dipentene dihydrochloride, C^^'H^^CX^,
(p. 1002), with aqueous alcohol, so called Terpine Hydrate, CjjiHjjOj -|- HjO,
will result. This is readily soluble in hot water, alcohol and ether. It is odor-
less, and forms large rhombic crystals, that melt at 117° in a capillary tube. Above
100° it loses water and changes to terpijie, CjoHjuOj ^= CjjHjj(0H)2, sub-
liming in needles, that melt at 104° and distil at 258° Terpine reacts like a
glycol. When digested with nitric acid it forms a dinitric ester.

Dihydrohaloid compounds, Ci„HjjX2, of dipentene, are formed when terpine,

LIMONENE AND DIPENTENE GROUP. lOOI

or terpine hydrate, is shaken with the haloid acids. Boiling sulphuric acid (l part
: 2H2O) causes terpine hydrate to lose water and form 7erpmeo/, C^^'H^,{OH)
(p. 1007). Bromine converts it into dipentene tetrabrotnide, Ci^Hj^Br^ (melting at
125°) [Anna/en, 230, 253; 239, 8).

Terpine hydrate and terpineol lose additional water by continued heating with
sulphuric acid and yield dipentenes, terpinenes and terpinolenes (see below). Ter-
pineol at the same time, yields isomeric cineol {Annalen, 246, 236).

(2) Camphene, CioHu, is the solid terpene, obtained from
pinene halogen hydride, by the elimination of the haloid acid.
A better method to pursue in its preparation is to boil bornyl chlo-
ride, CioHj^Cl, with aniline.

The camphenes from different sources differ from each other in rotatory power :
Terecamphene, from terebenthene, is laevo-rotatory, austracamphene, from Austra-
lene, is dextro-rotatory, while Borneo-camphene (Borneen), from borneol chloride,
is inactive. They are crystalline masses, melting at 49°, and boiling at 156-157°-
Chromic acid oxidizes them to ordinary camphor (active and inactive).

Camphene and hydrochloric acid form a liquid, unstable additive product,
CjjHjg.HCl, which is readily resolved into its components. Bromine does not
produce an additive, but rather a substitution product, Cj„Hj j'Br. Nor is it able to
form a nitroso-chloride. The assumption therefore that there are no divalent
unions in camphene, but two para-unions of the benzene nucleus is, in the opinion
of Wallach, unestablished (Berichte, 22, Ref. 585).

2. LIMONENE AND DIPENTENE GROUP.

These combine with two molecules of bromine or of a halogen
hydride, but not with N2O3.

I. Dextro-limonene, QoHis, Citrene, hesperidene, carvene, is
the oil of Cilrus aurantice, and the chief ingredient of cedar oil,
cumin oil and dill oil. It occurs associated with pinene in lemon
oil. LcRvo-limonene occurs together with laevo-pinene (boiling at
160°) in pine oil (from Pinus sylvestris), and may be isolated from
it by fractional distillation {Berichte, 21, Ref. 624.)

Both limonenes are agreeably smelling liquids, sp-gr. 0.846 at
20°, and boil at 175-176°. They differ from each other, even in
their derivatives, almost exclusively in their opposite rotatory
power.

Bromine converts each into a characteristic Tetrabrotnide, CjoHigBr^, that
crystallizes in large prisms, melting at 103°. The one is dextro- and the other
tevo-rotatory. They combine with two molecules of the halogen hydrides to
compounds of the type Ci^HuXj ; these are identical with the dipentene deriva-
tives; there has therefore been a rearrangement of the limonenes into dipentenes.

The Dextro-Nitroso-chloride, Ci„Hi5(N0)Cl, and the lavo-nitroso-chloride
result by the action of amyl nitrite and hydrochloric acid upon dextro and Isevo-
limonene. Both melt at 103°. They differ from each other solely in rotatory

84

IO02 ORGANIC CHEMISTRY.

power. Boiling alcohol converts the Isevo-nitroso-chloride into Dextro-nitroso-
limonene, Cj(|Hj5(N0) (by elimination of HCl), which melts at 72° and is
identical with dextro-carvoxime, Cj|,Hj4(N.OH), obtained from dextro-rotatory
carvol (p. 688) with hydroxylamine. Dextro nitroso-chloride, on the other hand,
yields a Itevo-nitroso-linionene or IcEvo-carvoxime, which also melts at 72°, and
otherwise corresponds perfectly with dextro carvoxime {Annalen, 246, 227 ; Be-
richte, 21, Ref. 624). Inactive carvoxime is produced by mixing dextro- and
laevo-carvoxime. It melts at 93°, and is identical with nitroso-dipentene (see
below).

As limonene combines four affinities quite readily (bromine or a halogen
hydride) it must very probably contain two divalent C-unions, and is a normal
dihydroparacymene. Its relation to carvol shows the position of the divalent

unions, corresponding to the formula, CjH,.^-,, ptr^ ^ CH.CHj (Gold-

Schmidt, Berichte, 18, 1733). \i.n _ >.,ti /

Dextro- and Isevo-limonene-nitroso chlorides can, by crystallization from chloro-
form, be resolved into two isomeric compounds, CjjHjg.NOCl (a. and j8), which
would further complicate the relations previously expressed (Berichte, 22, Ref.
583).

Dipentene, Cinene, QoHu, inactive Limonene, is the most
stable of the preceding terpenes, and is produced by heating
pinene, camphene and limonene to 250-300° (from pinene also by
the action of alcoholic sulphuric acid) ; it is, therefore, present in
the Russian and Swedish turpentine oil, obtained by application
of great heat (p. 1000). It is associated with cineol in Oleum cinae,
and is derived from terpine hydrate, terpineol and cineol by the
withdrawal of water, and further by the distillation of caoutchouc,
and the polymerization of the isoprene, CjHa, formed simiiltane-
ously. It may be prepared pure by heating its hydrochloride with
aniline or sodium acetate in glacial acetic acid solution. It results
upon mixing dextro- and laevo-limonene, and is, therefore, inactive
limonene. It is a liquid, with an agreeable lemon-like odor.

Its sp. gr. is 0.853. It is optically inactive and boils at 175-176°.
Although very stable, it can yet be changed into the isomeric ter-
pinene by alcoholic sulphuric acid, or hydrochloric acid.

Dipentene combines with two molecules of bromine or halogen hydride, forming
compounds that differ from those of the two limonenes, and hence it is regarded
as a peculiar isomeride. However, the same inactive compounds are also formed
by mixing the corresponding derivatives of dextro and laevo-limonene. Never-
theless, these synthetic derivatives (unlike the 'inactive racemic acid) have the
same molecular weights (in solution) as the active limonene compounds (Annalen,
246, 231).

Dipentene Tetrabromide, CuHuBr^ (see above), melts at 124-125°. Its
crystals are entirely different from those of limonene tetrabromide (melting at
104°). Dipentene Dihydrochloride, CjqHjjCIj, from limonene, dipentene and
moist pinene, consists of rhombic plates, melting at 50°. The dihydrobromide,
CjjHjjBrj, formed from terpine and cineol with hydrobromic acid, melts at 64° ;
the dihydroiodide, C]|)Hjjl2, consists of rhombic prisms, melting at 77°, or plates
that fuse at 79°. Dipentene-nitroso-chloride, Cj|,Hig(NO)Cl, from dipentene by

DEXTROPHELLANDRENE. IO03

means of amyl nitrite and hydrochloric acid, melts at 102°, is inactive and when
digested with alcoholic potash yields inactive Nitroso-dipentene, Cj„Hj5(NO),
melting at 93°. It is identical with the inactive carvoxime prepared from dextro-
carvoxime and Isevo-carvoxime.

(2) Terpinolene, Ci(,Hj5, is produced when terpine hydrate, terpineol and
cineol are boiled with dilute sulphuric acid, and by heating pinene with the con-
centrated acid. It boils at 185-190°. The ietrabromide, CmHigBr^, is a solid
melting at 116°. It combines with two molecules of the halogen hydrides to form
compounds, that are probably identical with those of dipentene.

(3) Sylvestrene, C,|,Hjs, occurs in Swedish and Russian turpentine oil. It
may be obtained pure by digesting its hydrochloride with aniline, or by boiling it
with glacial acetic acid and sodium acetate. It boils at 175 178°, and is optically
dextro-rotatory; this also is the case with its compounds. Sulphuric acid imparts
an intense blue color to its solutions in anhydrous acetic acid (or in acetic anhy-
dride). Its compounds with two molecules of bromine or the haloid acids are
different from those of all other terpenes. The tetrabromide , CjuHj^Brj, melts at
135°. The dihydrochloride, CijHigClj, melts at 72°, the dihydrobromide,
CioHjjBrj, also at 72°, and the dihydroiodide, Ci^HjjIj, at 67°. The nitroso-
chtoride, Cii,Hjg(NO)Cl, melts at 107°.

(3) Terpinenes and Phellandrene.

These do not unite either with bromine or the haloid acids ; consequently, they
probably do not have divalent unions in the benzene nucleus. However, like
amylene, they form nitrosites with N^Oj, and are probably unsaturated in the
side-chain {Annalen, 239, 54; Bericl^^ 21, 175).

Terpinene, Ci(,Hjg, results fromjjbarrangement of pinene, when the latter
is shaken with a little concentrated soMttte acid, and by boiling dipentene, ter-
pine, phellandrene and cineol with dii^^^Bphuric acid [Annalen, 239, 35). It
occurs already formed in cardamon oitKj^^B'ery similar to dipentene, boils about
180°, but forms liquid products with the n|PKa acids. It is the most stable of all
the terpenes, and is not changed into any other terpene. Nitrous acid converts it
into Terpinene Nitrosite, CjdHj j(NO)O.NO, melting at 155°, and yielding
nitrolamines with bases [Berichte, 22, Ref 585).

Dextrophellandrene, CjjHjg, occurs in the oil of water fennel (Phellanrlrium
aquaticum), etc. Lsevo-phellandrene is present in eucalyptus oil. Both boil
about 170°, and differ merely in opposite rotatory power. Both .become solid and
crystalline when shaken with sodium nitrite and acetic acid. They are then nitro-
sites, both of which melt at 103°- In this treatment dextro-phellandrene yields
lievo-nitrosite, and laevo-phellandrene, dextro-niirosite. By mixing the two nitro-
sites inactive nitrosite is formed; this fully agrees with the active nitrosites
{Annalen, 246, 232, 265 ; Berichte, 21, Ref 624);

For the terpenes contained in the various ethereal oils see Berichte, 22, Ref. 582.

Homologous terpenes have been prepared by the action of sodium upon a mixture
of camphor chloride, CjoHjgClj (p. 1005), and the alkyl iodides. Ethyl Camphene,
C]|,Hj5(C2H5), is a liquid with an odor resembling that of oil of turpentine, and
boiling at 198-200°. Isobutyl Camphene, <Zy^'ii^^{Cfi^), boils at 228°.

Sesquiterpenes are widely distributed in the ethereal oils. The sesquiterpene in
oil of cubeba, patchouly oil, galbanum oil and sabine oil, boils at 274-275°. It
forms a dihydrochloride, CJ5H24.2HCI, melting at u8°. It can be regenerated
from this compound by boiling with aniline {Annalen, 238, 78 ; Berichte, 21, 163).
Colophene is a diterpene, C^^YL^^, obtained by distilling colophony. It boils at
3l8°-

I004 ORGANIC CHEMISTRY.

CAMPHOR.

The camphors are peculiar-smelling substances, containing oxy-
gen and intimately related to the terpenes. They are often found
with the latter in plant secretions, and can be artificially prepared
(in slight quantities) by oxidizing the same. They are derivatives
of paracymene, CioHu, and mostly derivatives of its tetrahydride
CioHg. Japan camphor, CioHujO, is a keto-derivative of Borneo cam-
phor, CioHiaO, a hydroxy 1 compound of tetrahydro-cymene, corre-
sponding to the following formulas : —

/ CHj-CO \ /CH2-CH(0H)— C.CH3

CsH-.CH CCHjand C3H..CH ]|

\ CH,-CH^ \CHj CH

Japan Camphor Borneo Camphor.

The ortho-position of the oxygen atom with reference to the methyl group is evi-
dent from the ready conversion of Japan camphor into carvacrol or oxycymene
(p. 688), and from its analogies to carvol, a keto-derivative of a dihydrocymene
(p. 688). Menthol Cj|,H2qO, bears the same relation to menthone, CjqHjjO
(p. 1007) as Borneo camphor to Japan camphor; the one is an oxy-derivalive and
the other a keto-derivative of hexahydrocymene, Cj jHi^{H)5 : —

Menthone. jfl^ Menthol.

ire «ot

As Japan and Borneo camphor are Eot capable of forming additive products
(with bromine or haloid acids), it would appear that a double ethylene union is
not present in them ; their molecular refraction would also indicate it. To explain
this behavior it may be assumed, as in the case of camphene, that the benzene
neucleus contains a para-linkage (Bruhl, Berichte, 21, 467; Wallach, Annalen,
230, 269) corresponding to the formulas: —

/ CH..CO \ /CH5,.CH(0H)\

CjH-.C C.CH3 C3 H,.C C.CH3.

\CH,.Cn,/. \CH, CH,/

Japan Camphor. , « Borneol.

Common or Japan camphor is found in the camphor tree {Lau-
rus camphord) indi|;enous to Japan and China. It is obtained by
distillation with steam and sublimation. It is prepared artificially
by oxidizing borneol with nitric acid and camphene with chromic
acid. It is a colorless, transparent mass, crystallizes from alcohol,
and sublimes in shining prisms, of sp. gr. 0.985. It volatilizes at
ordinary temperatures, melts at 175°, and distils at 204°. Its alco-
holic solution is dextro-rotatory. Camphor yields pure cymene
(P- 577)> if distilled with P2O5, and on boiling with iodine forms
carvacrol CmHuO (p. 688). When boiled with nitric acid it yields
different acids, chiefly camphoric and camphoronic acids. The

CAMPHOR ALDEHYDE. 1 005

Camphoroxime, CioHi6(N.OH), obtained with hydroxylamine, melts
at 115° {Berichte, 22, 605) and distils about 250°.

Itunites likewise with phenyltydradne to Ha&hydrazideC^t^'R-^^ (NzH.CgH,).
Camphoroxime Anhydride, CioHjjN, results from the action of acetyl chloride
upon camphoroxime, or of hydrogen chloride upon phenylhydrazide. It boils at
217°. It is probably a cyanide with open chain, CH2.C(C3H,):CH2 a campho-
^'»'^^'"''- CH:C(CH3). CN,

The saponification of the nitrile yields campholenic acid, CgHjjCOjH (Gold-
schmidt, Berichte, 20, 485 ; 21, 1 129).

Chlorine and bromine acting upon camphor, produce mono- and disubstilution
products.

PCI5 converts camphor into two Camphor-dichlorides, Z^^YL^^Ci^ melting
at 70° and 155°.

Two Chlornitrocamphors,C^^'R^^C\{^0^0 {a and /?), are produced when
chlorcamphor is digested with nitric acid; the copper zinc couple reduces them to
u- and P-niirocamphor, Ci5Hj5(N02)0 {Berichte, 22, Ref. 266; 23, Ref. 115).

/CH2

Bornylamine, CijHjj.NHj = CjHj / • , a solid base, melting at

^CH.NHj
160°, is formed when camphor is heated together with ammonium formate to 240°
(Berichte, 20, 104, 483). Bornylamine shows in all respects the character of an
alicyclic amine (p. 912). Its odor resembles that of piperidine. It is strongly
alkaline, absorbs carbon dioxide from the air, yields a diazoamidoderivative
(not an azo-dye) with diazobenzene chloride, and forms a niti;ite with nitrous acid
{Berichte, 21, 1128).

Camphylamine, C^f,li^^.'iiili^ = C^n^{C^Yl^){Cii^).Cii^.^'R^, is iso-
meric with the preceding compound. It is formed when sodium and alcohol act
upon camphoroxime. It is very probable that the benzene chain present in it is
open. It is a liquid boiling at 195°. Its properties resemble those of the amines of
the paraffin series {Berichte, 20, 485; 21, 1 128).

CO

Isonitroso-camphor, C,|,H,,0(N.OH) = C.H,^:' • , is obtained by

^CiN.OH
the action of amyl nitrite and sodium ethylate upon camphor. A CH^-group is
replaced. The compound melts at 153°. Nitrous acid, or sodium bisulphite and
boiling with dilute sulphuric acid (p. 326), changes it to camphor-quinone =

/CO
CijHj^Oj = CgH^/ ■ . The latter resembles, quinone and the (i, 2)-dike-

^CO
tones. Its odor is peculiarly sweet. It volatilizes with aqueous vapor and sub-
limes at 60° in golden yellow needles that melt at i98°,(Claisen, Berichte, 22,
530).

Sodium Camphor and Sodium-Borneo-camphor ifparais when metallic sodium
acts upon the benzene or toluene solution of camphor : —

2CioH,,0 + 2Na = Ci„H„NaO + Ci„H„.ONa.

Campholic acid, C^^'R^fi^, and borneol, CioHuO, are similarly formed when
camphor is heated with alcoholic potash. The alkyl iodides convert sodium cam-
phor into alkyl camphor. Ethyl Camphor, C^^\\^{C^Yi^^O, boils at 230°.

/CO /CO

Camphor Aldehyde, CjHj^ ■ or CjH^ • ,meltsat77°.

^ \CH.CHO \C:CH(OH)

IOo6 ORGANIC CHEMISTRY.

It is formed by the action of sodium or sodium ethylate and formic ester upon
camphor (analogous to the formation of the /3-ketonaldehydes, p. 323, 730). It is
perfectly analogous to the ^-ketonaldehydes. It is acid in nature, and dissolves
readily in the caustic alkalies [Berichte, 22, 533, 3281 ; 23, Ref. 39).

The camphors, like the turpentine oils, occurring in different plants, manifest
some differences. Matricaria camphor, Cj„HjjO, or Lcevo-camphor, contained
in the oil of Matricaria Parthenium, is lievo-rotatory, and when oxidized with
nitric acid yields loevo-camphoric acid. LaEvo-camphoroxime, Cj (|H]5(N.0H),
also melts at 115°. Absinthol, CjoHj^O, from oil of wormwood (from Arte-
mesia Absinthium'),\s liquid, and boils at 195°. Myristicol, Ci^HjgO, from
nutmeg-oil, boils at 235°. Pinol, CjqHijO, a by-product in the preparation of
pinene nitroso chloride, is isomeric with camphor. It boils at 183—184°. Potassium
permanganate oxidizes it to terebinic acid, C^Hj^Oj. Patchouly Camphor,
C] jHjgO, from Patchouly oil, is a sesqui-camphor. It melts at 55° and boils at
246°. Caryophyllin, Cj^HjjOj, is a polymeric camphor, contained in cloves, and
melts above 300°.

Borneol, Borneo Camphor, CioHia 0= CioHn.OH, occurs
in Dryobalanops Camphora, a tree growing in Borneo and Sumatra.
It is artificially prepared by acting with sodium upon the alcoholic
solution of common camphor, and bears the same relation to the
latter as an alcohol to a ketone. It is quite like Japan camphor,
and has a peculiar odor resembling that of peppermint. It sublimes
in six-sided leaflets, melts at 198°, and boils at 212°.

Nitric acid oxidizes borneol to common camphor, and then to camphoric acid.
Borneol possesses the character of an alicyclic alcohol (of ac-tetrahydro-^S-
naphthol, p. 916) {Berichte, 23, 201). It forms esters with organic acids, xan-
ihogenates with CS^ (Berichte, 23, 213), and is especially inclined to form camphene,
CjjHjg, by the elimination of water. The acetyl ester, CjgHj^.O.CjHjO, boils at
221°. Bornyl Chloride, Ci„Hj,Cl, melting at 148°, is produced bymeans of PCI5.
It forms borneo camphene by the elimination of HCl.

Laevo-borneol, CijHjj.OH, is optically opposed to ordinary dextro-borneol.
It is produced, together with the latter, when sodium acts upon ordinary camphor.

Cineol and Terpineol are isomerides of borneol.

Cineol, CijHjgO, is the chief ingredient of worm-seed oil (Artemisia cinse),
cajeput oil and eucalyptus oil. It boils at 176°. Its specific gravity at 16° is
0.923. It forms an unstable hydrochloride additive product, which water resolves
into its components. Hydrochloric acid gas conducted into heated cineol produces
dipentene-dihydro-cbloride, CiqHjj.zHCI (p. 1002") ; hydriodic acid gas forms the
dipentene-dihydro-iodide, C^^^^.iYil (melting at 78°). PjSj converts cineol into
cymene. See Berichte, 21, J^6o , 23, Ref 642, upon the constitution of cineol.
Potassium permanganate oxidizes cineol to cineolic acid, CjqHjjOj, melting at
197° {Berichte, 21, Ref. 625 ; 23, Ref 641).

Terpineol, C,|,H] ,0, formed by boiling terpine and terpine hydrate (p. 1000)
with aqueous mineral acids, is a thick liquid with a peculiar odor. It boils at
215-218°. It is also produced when pinene stands in contact with alcoholic sul-
phuric acid; by further absorption of water it yields terpine hydrate. See Berichte,
21, 463, in regard to its constitution.

Menthol, Mentha Camphor, CioH^oO = C,oH,9.0H, oxy-
hexahydrocymene (p. 1004), is the chief component of peppermint
oil (from Mentha piperita), from which it separates in crystalline

CAMPHORIC ACID. IO07

form on cooling. It possesses, like borneol, the character of an
alicyclic alcohol. It melts at 42°, boils at 213°, and is Isevo-
rotatory. It forms esters with acids and readily parts with water.
With concentrated hydrochloric acid, or PCI5, it yields liquid men-
thol chloride, C10H19CI, boiling at 264°.

Menthene, CijHjg, is produced when the chloride is acted upon by allcalies, or
when menthol is distilled with PjOj. It boils at 167°. Chromic acid oxidizes
menthol to dextro- and lavo-menthone, CjqHijO, which sustain the same relation
to menthol that ordinary camphor bears to borneol. The menthones are liquids
with an odor resembling that of peppermint. They boil at 206°. They form ox-
imss with hydroxylamine. Dextro-menthone Oxime, Ci5Hjg(N.0H), is liquid.
LcBVo-menihone Oxime melts at 58°. Acids cause the menthones to change
readily from one modification to the other {Berichte, 22, Ref. 261). Their activity
is due to the asymmetry of a carbon atom [Annaten, 250, 362).

The oxidation of the camphors produces different acids, whose constitution has
not yet been explained.

Campholic Acid, Cj^Hj jOj, is produced on distilling camphor over heated
soda-lime, or with alcoholic potash. It melts at 95° and volatilizes with steam.
Nitric acid oxidizes it to camphoric and camphoronic acids.

Camphoric Acid, CioHisOj = CgHuCCOjH),, is obtained by
boiling camphor with nitric acid {Annalen, 163, 323"). It crystal-
lizes from hot water in colorless leaflets, melts at 178°, and decom-
poses into water and its anhydride, C8Hi4(CO)20 ; the latter sub-
limes readily in shining needles, melts at 217°, and boils at 270°.

The acid from common camphor is dextro-rotatory, that from Matricaria cam-
phor is, however, lasvo-rotatory and melts at 197°- The inactive meso-camphoric
acid is produced on mixing the two acids. It melts at 113°, and is derived from
ordinary camphoric acid by heating the latter with hydrochloric acid to 140°.

By the fusion of camphoric acid with potash we get isopropyl succinic acid,
C2H3(C3H,)(COjH)2.

From its constitution camphoric acid may be considered either as an unsaturated
methylpropyl adipic acid, C5Hg(CH3){C3H,)04 {Annalen, 220, 278), or, inas-
much as it cannot form additive compounds, it may be regarded as methyl-pro-
pyl tetramethylene dicarboxylic acid, in accordance with the formulas : — •

CH:C(CH3).C02H CH2.C(CH3).C02H

I or I I

CH{C3H,).CH2.C02H CH2.C(C3H,).CO,H

Camphoronic Acid, C^n^fi^ + Hp, is produced by the further oxidation
of camphoric acid ; it occurs in the mother liquor. It loses its water of crystal-
lization at loo-i 20°, and melts at 135°. It is tribasic, yields isobutyric acid when
fused with potash, and appears to be an isopropyl tricarballylic acid {Berichte,
Ref. 71 and 18, 328).

IOo8 ORGANIC CHEMISTRY.

RESINS.

The resins are closely related to the terpenes, and occur with
them in plants, and are also produced by their oxidation in the air.
Their natural, thick solutions in the essential oils and turpentines
are called balsams, whereas the real gum resins are amorphous,
mostly vitreous bodies. Their solutions in alcohol, ether or tur-
pentine oils constitute the commercial varnishes.

Most natural resins appetir tp consist of a mixture of different,
peculiar acids, the resin acids.- The alkalies dissolve them, forming
resin soaps, from whiclf acids again precipitate the resin acids. By
their fusion with alkalies we obtain different benzene derivatives
(resorcinol, phloroglucin, proto'-catechuic acid) ; and when they
are distilled with zinc dust they yield benzenes, naphthalenes, etc.

Colophony is found in turpentine (p. 999), and, in the distillation of the latter,
remains as a fused mass. It consists principally of Abietic Acid, C^^Hj^Oj
(Sylvic acid), which can be extracted by hot alcohol, crystallizes in leaflets, and
melts at 139° (147°). When oxidized it yields trimellitic, isophthalic and tere-
binic acids.

Gallipot Resin, boTa Finns maritima, contains pimaric acid, Q-^^^Mi^^O^,
which is very similar to sylvic acid and passes into the latter when distilled in
vacuo. It melts at 210°. The latest investigations show that pimaric acid con-
sists of three isomerides [Benc/ite, ig, 2167).

Gum lac, obtained frona East India fig trees, constitutes what is known as shel-
lac when fused. This is employed in the preparation of sealing wax and varnishes.

Amber is a fossil resin, found in peat-bogs. It consists of succinic acid, two
resin acids and a volatile oil. After fusion it dissolves easily in alcohol and tur-
pentine oil, and serves for the preparation of varnishes.

To the ^m resins, occurring mixed with vegetable gums, and gum in the juice
of plants, belong gamboge, euphorbium, asafoetida, caoutchouc and gutta percha.

GLUCOSIDES.

These substances occur in plants and split into sugars (mostly
grape sugar), and other bodies (alcohols, aldehydes, phenols), when
acted on by acids or ferments. Therefore they are assumed to be
ethereal derivatives of the glucoses. Various members of this series,
obtainable also by synthesis, have already received notice in con-
nection with the products they yield when they are decomposed.
The following have not been fully investigated : —

^sculin, CjjHjjOg, is contained in the bark of the horse chestnut ; it crystal-
lizes in fine needles with lyi, molecules HjO, melts when anhydrous at 205°, and
is decomposed by acids or ferments into glucoses and sesculetin, CgH^O^ (Dioxy-
coumarin, p. 822). Daphnin, CjjHjjOg -\- 2H2O, is isomeric with Ksculin,

BITTER PRINCIPLES. IOO9

and is obtained from the bark of Daphne alpina. It melts at 200°, and breaks
down into glucose and daphnetin (Dioxycoumarin, p. 823).

Arbutin, Cj^HjgO,, and Methyl Arbutin, CjjHjgO,, are found in the leaves
of Arhulus uva ursi. By their decomposition, we get, besides grape sugar, hydro-
quinone or methyl hydroquinone. Arbutin crystallizes in fine needles, with yi-l
molecule of water, melts at 187° [Berichle, 16, 1925) in the anhydrous state, and
is colored a deep blue by ferric chloride. Methyl Arbutin contains I molecule of
water, and melts at 176°. It is formed artificially from arbutin by the action of
methyl iodide and potash.

Hesperidin, Cj^HjjOjj, is present in the unripe fruit of oranges, lemons, etc.
It separates from alcohol in fine needles, melts at 251°, and is decomposed into
grape sugar and Hesperitin, Cj^Hj^Og, which by further boiling with potassium
hydroxide breaks up into hesperitinic acid (isoferulic acid, p. 821), and phloro-
glucin, C6H3.(OH)3.

Phloridzin, C^^Yi^fi^^, occurs in the root bark of various fruit trees, crystal-
lizes with 2H2O in fine prisms, and when 'anhydrous melts at 108°. By decom-
position it yields grape sugar and Phloretin, CjjHjjOu (colorless leaflets), which
alkalies convert into phloretic acid (p. 775), and phloroglucin.

Quercitrin, Cji-^HjgOjj, is found in the bark of Quercus tinctoria, and is
applied as a yellow dye under the name Quercitrone. It consists of yellow
needles or leaflets, which are decomposed into isodulcitol and Quercitin,
Q4H16O11 "h 3H2O. The latter forms an hexa-ethyl and octo-acetyl derivative
{Berichte, 17, 1680). Fused with alkalies it yields quercitinic acid, CjjHjqO,,
protocatechuic acid and phloroglucin.

Saponin, ^^■fi-ifivi,, in the roots of Saponaria offichialis, is a white amor-
phous powder, provoking sneezing, and in aqueous solution forms a strong lather.
Its decomposition products are glucose and sapogenin, Q.-^fi,^^0^.

Glucosides whose decomposition products belong' to the fatty series are : —

Convolvulin, CjiHjjOig, derived from the roots of Jalap (from Convolvulus
turga). It is a gummy mass, and is a strong purgative. It dissolves in alkalies
to Convolvulic Acid, CgjHjjOj, (?), which nitric acid converts into Ipomic
Acid, CieHj.O^ = CjHielCO.H),.

Jalapin, CjiHsjOig, from Convolvulus ortzabensis, is very similar to con-
volvulin, and forms analogous derivatives.

Myronic Acid, CioHjgNSjOm, occurs as potassium salt in the seeds of black
mustard. This crystallizes from water in bright needles. On boiling it with
baryta water, or by the action of the ferment my rosin, present in the seed, the salt
decomposes into glucose, allyl mustard oil, and primary potassium sulphate :—

CjoH,8KNS,Oj„ = Cfi^f>, + C3H5.N:CS -f- SO.KH.

BITTER PRINCIPLES.
Under the head of " bitter principles," or indifferent substances,
is embraced a class of vegetable bodies whose chemical character is
but indistinctly indicated. Many of them have already found their
place in the chemical system. Those yet uninvestigated are :—

Aloin, C„H,„0,, found in aloes, the dried sap of many plants of the aloe
variety. It forms fine needles, possesses a very bitter taste, and acts as a strong

10 10 ORGANIC CHEMISTRY.

purgative. If digested with nitric acid it yields a/oeiic aaW,Ci^il^{1>l02)^02,
and chrysanimic acid (p. 900). It forms alorcinic acid, CgHjQOj.-fr HjO, when
fused with caustic potash. This breaks down into orcin and acetic acid.

Cantharidin, Cj|,Hj204, contained in Spanish flies and other insects, crystal-
lizes in prisms or leaflets, melts at 218°, and sublimes readily. It tastes very bitter
and produces blisters on the skin. It dissolves when heated with alkalies and
forms salts of cantharinic acid, CjjHjjOj = CgHjjOj.CO.COjH. Hydriodic
acid converts cantharidin into cantharic acid, CnjHjjO^ = CjHjjO.CO.COjH,
isomeric with it.

Picrotoxin, CjjHjgO^ + HjO, is found in the grains of cockle, and crys-
tallizes in fine needles, melting at 201°. It has an extremely bitter taste and is very
poisonous.

Santonin, CjjHjgOj, is the active principle of worm-seed, crystallizes in
shining prisms, and melts at 170°. It dissolves in alkalies to salts of Santonic
Acid, CjjH^jO^, which breaks down at 120° into water and santonin. On boil-
ing with baryta water we have formed salts of isomeric santoic acid, C,5H2„04,
which melts at 171°. Santonin, therefore, bears the same relation to these two
acids as coumarin to coumarinic and coumaric acids. When santonin is boiled
with hydriodic acid a- and P-meta santonin, santonid and para santonid (Canni-
zaro, Berichte, 18, 2746; 22, Ref. 732), — compounds isomeric with santonin — are
produced.

The following are unstudied coloring matters ; some of them ap-
pear to have a constitution analogous to the phthaleins (p. 881) : —

Brasilin, CuHj^Oj, is found in Brazil-wood and red wood; crystallizes in
white, shining needles, and dissolves in alkalies with a carmine-red color on ex-
posure to the air. Acids then precipitate brasilin, CjgHjjOs + H^O, from the
solution. The action of iodine upon brasilein also produces this compound. It
regenerates brasilin by reduction. When distilled it yields resorcinol (^Berichte,
23, 1428).

Carthamin, Cj^H^jO,, occurs in safflower, the blossoms of Carthamus tine-
torium, and is precipitated from its soda solution by acetic acid, as a dark red
powder, which, on drying, acquires a metallic lustre. It dissolves with a beautiful
red color in alcohol and the alkalies. It yields para-oxybenzoic acid with caustic
potash.

Curcumin, Cj^Hj^O^, the coloring matter of turmeric. Crystallizes in orange-
yellow prisms, melts at 177°, and dissolves in the alkalies to brownish-red salts.
Ethyl vanillic acid is obtained on oxidizing diethyl-curcumin with potassium
permanganate.

Euxanthinic Acid, CjgHjjOu (Porrisic acid), occurs as magnesium salt in so-
called purree (jaune indien), a yellow coloring matter from India and China,
{^Anna/en, 254, 265). It crystallizes from alcohol in yellow prisms with one
molecule of water. When boiled with dilute sulphuric acid it splits up into gly-
curonic acid and euxanthone, CjjHgOj (p. 85o).

Haematoxylin, CjgHnOg, the coloring matter of logwood (Hsematoxylon
Campechianum), is very soluble in water and alcohol, and crystallizes in yellowish
prisms with 3H2O. It dissolves in alkalies with a violet-blue color. When dis-
tilled or fused with potassium hydroxide, pyrogallic acid and resorcinol result from
it. If the ammonium hydroxide solution be allowed to stand exposed to the air
there results haematein-ammonia, CijHjj(NH4)Oe, from which acetic acid

BILIARY SUBSTANCES. 101 1

liberates Hsematein, Cj^H^jOg, a red-brown powder with metallic lustre, when
dried.

Gentisin, CnH^pOj, contained in the Gentian root, crystallizes in yellow
needles, and fused with caustic potash yields hydroquinone carboxylic acid (p. 778)
and phloroglucin.

Carminic Acid, C^H^jOj^, occurs in the buds of certain plants, and espe-
cially in cochineal, an insect inhabiting different varieties of cactus. It is an
amorphous purple-red mass, very readily soluble in water and alcohol, and yields
red salts with the alkalies. When boiled with dilute sulphuric acid it splits into a
non-fermentable sugar and carmine-red, CjiHjjO,. When distilled with zinc
dust it yields the hydrocarbon, CjgHj^. On boiling carminic acid with nitric acid
we get nitrococcic acid.

Chlorophyll occurs in the chlorophyll granules in all the green parts of plants.
Wax and other substances are associated with it. We do not yet know its consti-
tution. There seems to be an essential quantity of iron in it.

The following are animal substances the more extended discus-
sion of which belongs to the province of physiological chemistry.

BILIARY SUBSTANCES.

In the bile, the liquid secretion of the liver, essential to the
digestion of fats, occur (in addition to fats, raucous substances and
albuminoids) the sodium salts of two peculiar acids, glycocholic
and taurocholic ; also cholesterine and bile pigments (bili-
rubin, biliverdin).

Cholesterine, C2eH4iO(C2,H,sO) (5mV/5/^, 21, Ref. 657), occurs in not only
the bile, but in the blood, in the brain, and in the yolk of eggs, also m the seed
and sprouts of many plants, in which it is often confounded with the fats. It is
soluble in alcohol and ether, crystallizes in mother-of-pearl leaflets, contammg
iHjO, and possessing a fatty feel. It parts with its water of crystallization at
100°, melts at 145°, and distils at 360° with scarcely any decomposition. If sul-
phuric acid be added to the chloroform solution of cholesterine, the chloroform
acquires a purple-red color, and on evaporation assumes a blue, then green, and
finally a violet coloration. Chemically cholesterine behaves like a monovalent
alcohol, and forms esters with acids. . . i, 1. 1

Isocholesterine, Q.H.^O, an isomeric body, occurs associated with choles-
terine in distilled sheeps' fat, melts at 138°, and does not give any color reactions
with chloroform and sulphuric acid. Phytosterine, present in plant seeds and
sprouts, is very similar to cholesterine, and is frequently confounded with the fats

Lanoline, obtained from raw sheeps' wool, contains esters of cholesterine and
isocholesterine with the higher fatty acids. It is applied as a salve, as it will take
up water and is absorbed by the skin. , r •.

Glycocholic Acid. C,3H,3NOe, separated in crystalline form from is
sodium salt (found in bile) by dilute sulphuric acid, is sparingly soluble in water. It
crystallizes in minute needles, melting at 133°. On adding a sugar solution and
concentrated sulphuric acid or phosphoric acid to glycocholic acid we obtain a

I0I2 ORGANIC CHEMISTRY.

purple-red color. Boiled with alkalies it decomposes into glycocoU and cholic
acid.

Taurocholic Acid, Cj^H^jNOS,, is very soluble in water and alcohol, crys-
tallizes in fine needles, and when boiled with water breaks up into cholic acid and
taurine. For the separation of glycocholic acid and taurocholic acid from bile see
Journ.pract. Chem., ig, 305.

Cholic Acid, Cholalic KqX&,Q.^^^^O^ (BericAie, ig, 20og ; 20, 1968) or
^25^42^5 [SericA/e, 20, 1052), from glyco- and taurocholic acids, crystallizes
from hot water in small anhydrous prisms, which dissolve with difficulty in water,
and when anhydrous melt at 195°. It reacts the same as glycocholic acid with
sugar and sulphuric acid. It is monobasic ; its esters are crystalline. It forms a
blue compound with iodine, quite similar to that given by starch and iodine
[Berichte, 20, 683).

GELATINOUS TISSUES AND GELATINES.

These are mostly nitrogenous, organized substances, which on
boiling with water are converted into gelatines and are distinguished
as collagenes and chondrogenes . The former constitute bone cartilage
and sinews, the connective tissues, the skin and fish-bladder, and
afford the ordinary true gelatines ; the latter contained in the un-
hardened cartilage, yield chondrin. As regards composition, both
are very similar to the albuminoids, but differ from the latter,
mainly in that they are not precipitated by nitric acid and potas-
sium ferrocyanide.

Glutin, gelatine, is precipitated from its aqueous solution by alcohol, and when
pure is a colorless, solid mass, without odor and taste. In cold water it swells
up, and on boiling dissolves to a thin solution, which gelatinizes on cooling. By
the addition of concentrated acetic acid or protracted boiling with a little nitric
acid, the solution loses the property of gelatinizing (liquid gelatin). Tannic acid
precipitates from the aqueous solution gelatine tannate, a yellowish, glutinous
precipitate. The substances yielding gelatine combine also with tannic acid,
withdrawing the latter completely from its solutions and forming leather.

GlycocoU and leucine are the principal substances produced on boiling gelatine
with sulphuric acid or alkalies. Dry distillation produces bases of the fatty and
pyridine series .

Alcoholic hydrochloric acid changes gelatine into a compound that nitrous acid
converts into a substance, C5H5N2O3, very similar to the diazo fatty-acids. It
may be that it represents diazo-oxyacrylic ester, CN2:C(OH).C02.C2H5 {Be-
richte, ig, 850).

Chondrin, from bone cartilage, is very similar to the preceding, and is distin-
guished from it by the fact that it is precipitated from its aqueous solution by
alum, lead acetate, and most metallic salts; on the olher hand, it is not precipi-
tated by mercuric chloride, whereas it is otherwise with glutin. It affords leucine
and not glycocoU if boiled with dilute sulphuric acid. Chitine belongs to the
class of substances present in bone cartilage. It is the chief component of the
shells of crabs, lobsters, etc. Boiling acids convert it into glucosamine,
•^^eHisNO^ (p. 50s).

ADBUMINOID SUBSTANCES, ALBUMINATES. IOI3

ALBUMINOID SUBSTANCES, ALBUMINATES.

These were formerly known as protein substances, and form
the principal constituents of the animal organism. They also occur
in plants (chiefly in the seeds), in which they are produced exclu-
sively. When absorbed into the animal organism as nutritive
matter they sustain but very slight alteration in the process of
assimilation.

They exhibit great conformity in their properties and especially
in their composition, as seen from the following percentage numbers
of the three most important varieties of albumen : —

Albumen.

Fibrin.

Casein.

c

53-5 per

cent.

52.7 per

cent.

S3. 8 per cent.

H

7.0 "

<(

6.9 "

(C

7.2 " "

N

15.S "

"

15-4 "

it

15.6 " "

0

22.4 «

"

23.8 "

l(

22.5 " "

S

1.9 "

*'

1.2 «

It

0.9 " "

Owing to indistinct chemical character and great power of
reaction, no accurate molecular formulas have been deduced for
the albuminoids up to the present. The formula of Lieberkiihn,
CjjHjijSNigOuj, affords an approximate representation. Loew thinks
this should be trebled {^Berichte, 23, 43 ; 22, 3046).

The decomposition products of the albuminoids give us an idea
as to their constitution. These they yield when boiled with dilute
sulphuric or hydrochloric acid, or with baryta water.

The decomposition products are mainly amido-acids of the fatty
series : glycocoll, leucine, leucelnes, C„H2„ jOj (unsaturated gly-
cines), aspartic and glutaminic acids, C5H9NO4 (p. 467), as well as
phenylamidopropionic acid, tyrosine, etc. All albuminoids yield
the same products, only in relatively different amounts, therefore
they must be assumed to form from the union of these constituents
(See Berichte, 18, Ref. 444; 19, Ref. 30, 697).

Putrefaction causes a similar decomposition, but in addition to amido-acids fatty
acids and aromatic acids, as well as phenols, indol, skatole and skatole- acetic acid
are produced [Berichie, 22, Ref. 702). Basic compounds also result in this de-
composition. These are the diamines and imines of the paraffin series, and have
been csMed. ptomaines or toxines (p. 316).

Certain pathogenic micro-organisms, as diphtheria and anthrax bacilli, produce a
decomposition that is far more extended, and results in the formation of poisonous,
substances somewhat similar to albumen and peptone, which have been termed
toxalbumens ; these lose their toxic properties when their aqueous solutions are
heated {Berichte, 23, Ref. 351).

Tuberculin is a member of this series. It is the active substance that has been
extracted by means of aqueous glycerol from tubercular bacilli cultures. The
percentage content of its solution is not known, its composition is unknown, its
injurious action has never been determined and yet it has, very recently, been sug-
gested as a curative for tuberculosis.

I014 ORGANIC CHEMISTRY.

Most albuminoids exist in two modifications, one soluble the
other insoluble in water. Alcohol, ether, tannic acid, many mine-
ral acids and metallic salts reprecipitate them from their aqueous
solutions. In their coagulated condition they are dry, white, amor-
phous masses. Most of them dissolve in dilute mineral acids, all,
however, in concentrated acetic acid and in phosphoric acid on
application of heat. Ferro- and ferri-cyanide of potassium precipi-
tate them from their dilute acetic acid solution. They dissolve in
dilute alkalies, with the separation of sulphur in form of sulphide.
The substances reprecipitated by dilute acetic acid are very similar
to the albuminoids employed.

Reactions. — All albuminoids are colored a violet red on warming with a mer-
curie nitrate solution containing a little nitrous acid (this is like tyrosine). On
the addition of sugar and concentrated sulphuric acid they acquire a red colora-
tion, which on exposure to the air becomes dark violet. If concentrated sul-
phuric acid be added to the acetic acid solution of albuminoids they receive a
violet coloration and show a characteristic absorption band in the spectrum.

Gastric juice, pepsine and dilute hydrochloric! acid, and various other ferments
dissolve the albuminoids at 30-40°, converting them first into anti- and hemi albu-
minoses, which later become so-called /^/OBW. These dissolve readily in water,
are not coagulated by heat and are not precipitated by most of the reagents [Be-
richte, 16, 1152; i7i Ref. 79).

The manner of distinguishing and classifying the various albumi-
noids is yet very uncertain. According to the manner in which
they pass from the soluble into the insoluble state we distinguish
three principal groups of albuminoids ; the albumins, fibrins and
caseins. The first are soluble in pure water, coagulate when heated
alone or after acidulation with a few drops of nitric acid, and are
then no longer soluble in dilute potassium hydroxide or acetic acid.
The fibrins coagulate immediately after their exit from the animal
organism. The caseins (legumins) are almost insoluble in water,
dissolve, however, very readily in dilute alkalies and alkaline phos-
phates, and are again precipitated from these solutions on acidulating
them.

I. The albumins exist in the folio wing -varieties: —

Egg Albumin is obtained by precipitating its aqueous solution with basic lead
acetate, decomposing the precipitate with carbon dioxide and hydrogen sulphide
and then reducing the filtrate at a temperature below 60°. It is a yellowish,
gummy mass, which swells up in water and then dissolves. The perfectly neutral
solution coagulates at 72-73°; it is laevo-rolatory and is precipitated by alcohol,
by shaking with ether and by dilute acids.

Serum Albumin occurs in the blood, in the lymph and in the various secre-
tions. It is obtained from the blood serum diluted with water (subsequent to the
removal of other albuminoids by a little acetic acid) in the same manner as egg
albumin. It resembles the latter, but is not precipitated by dilute mineral acids.

Vegetable Albumin occurs in almost all vegetable juices. It coagulates on

ALBUMINOID SUBSTANCES, ALBUMINATES. I015

warming and is very similar to egg fibrin. Vitellin, contained dissolved in the
yellow of the egg, appears to be a mixture of albumin and casein.

2, Fibrins.

^Blood fibrin separates from the blood after the latter has been discharged from
the organism. It seems that it does not exist already formed in the blood, but
that it results by the union of the so-cal\d fibrinoflastic (contained in the serum)
axA fibrinogen (in the blood corpuscles) substances. Fibrin is obtained by whip
ping the fresh blood, when it separates in long fibres, which are freed from blood
corpuscles by long-continued kneading under water. It is a whitish, sticky,
fibrinous mass, which becomes hard and brittle upon drying. It is insoluble in
water, dilute hydrochloric acid and a solution of common salt.

Myosin constitutes (with water) the chief constituent of the muscles, in which
it seems to exist in a dissolved state. It is obtained by dissolving the well washed
muscles in a moderately dilute sodium chloride solution and precipitating the
filtrate with salt. Vegetable fibrin occurs in an undissolved state in the grain
granules. On kneading flour (stirred to a paste) under water, the starch granules
are washed out, together with the soluble albumin, and there remains a pasty mass
called gluten, which, according to Ritthausen, consists of glicidin (vegetalile
gelatine), mucedin and gluten fibrin. The latter is soluble in dilute alcohol and
acids. When seeds sprout the vegetable fibrin is converted into the soluble fer-
ment called diastase [Berichte, 23, Ref 210). The other unformed ferments
(p. 508) appear also to be modified albuminoids.

2. Caseins.

Milk casein occurs dissolved in the milk of all mammalia, and on the addition
of hydrochloric acid separates as a flocculent precipitate, which is washed out
with water, alcohol and ether (for the removal of the fats). Pure casein is not
soluble in pure water, but in water containing a little hydrochloric acid or
alkali. When the solutions are neutralized it is reprecipitated. The solutions do
not coagulate until heated to 130-140°. If a few drops of hydrochloric acid or
rennet be added to milk all the casein will be co-precipitated with the fat globules
(cheese) ; in the solution (whey) remain milk, sugar, lactic acid and salts.

Vegetable Casein, or Legumin, occurs chiefly in the seeds of leguminous plants,
and is perfectly similar to casein. It is precipitated from the pressed out juice by
acids or rennet.

In concluding the albuminates mention may be made of the hcemoglobins and
lecithin.

The oxyhcemoglobins are found in the arterial blood of animals and may be ob-
tained in crystalline form from the blood corpuscles by treatment with a solution
of sodium chloride and ether, and the addition of alcohol. The different oxy-
haemoglobins, isolated from the blood of various animals, exhibit some variations,
•especially in crystalline form. They are bright red, crystalline powders, very
soluble in cold water, and are precipitated in crystalline form by alcohol. When
the aqueous solution of oxyhasmoglobin is placed under the air pump or through
the agency of reducing agents (ammonium sulphide) it parts with oxygen and be-
comes hamoglobin. The latter is also present in venous blood and may be sepa-
rated out in a crystalline form (Berichte, 19, 128). Its aqueous solution absorbs
oyxgen very rapidly from the air, and reverts again to oxyhaemoglobin. Both
bodies in aqueous solution exhibit characteristic absorption spectra, whereby they
may be easily distinguished.

1 01 6 ORGANIC CHEMISTRY.

If carbon monoxide be conducted into the oxy-haemoglobin solution, oxygen is
also displaced and heemoglobin-carbon monoxide formed. This can be obtained
in large crystals with a bluish color. This explains the poisonous action of carbon
monoxide. The bluish-red solution of haemoglobin-carbon monoxide shows two
characteristic absorption spectra. These do not disappear upon the addition of
ammonium sulphide (distinction from oxy-hsemoglobin).

On heating to 70°, or through the action of acids or alkalies, oxyhsemoglobin
is split up into albuminoids, fatty acids and the pigment hcEinatin, which in a dry
condition is a dark brown powder. It contains 9 per cent, iron^ and, as it appears,
corresponds to the formula, C34H34FeN405.

The addition of a drop of glacial acetic acid and very little salt to oxyhaemo-
globin (or dried blood) aided by heat, produces microscopic reddish-brown crys-
tals of haemin (haematin hydrochloride) (Berichte, 18, Ref. 232) ; alkalies separate
haematin again from it. The production of these crystals serves as a delicate
reaction for the detection of blood.

Lecithin, C^j^seNPOg (Protagon), is widely distributed in the animal organ-
ism and occurs especially in the brain, in the nerves, the blood corpuscles, and
the yellow of egg, from which it is most easily prepared. It is a wax-like mass,
easily soluble in alcohol and ether, and crystallizes in fine needles. It swells up
in water and forms an opalescent solution, from which it is reprecipitated by various
salts. It unites with bases and acids to salts, forming a sparingly soluble double
salt, (C^jHj^^NPOg.HC^j.PtCl^, with platinic chloride. Lecithin decomposes
into choline, glycerol-phosphoric acid (p. 454), stearic acid and palmitic acid,
when it is boiled with acids or baryta water. Therefore we assume it to be an
ethereal compound of choline with glycero-phosphoric acid, combined as glyceride
with stearic and palmitic acids : —

/O.Ci,H,50
""^""^Wb^ofe^O.cSlN-OH = lecithin.

INDEX

Abietic acid, 1008
Absinthol, ioo5
Acediamine, 294
Acenaphthene, 909
Acetal, 305
Acetaldehyde, 193
Acetamide, 259
Acetanilide, 607
Acetic acid, 219

anhydride, 249
esters, 254
Aceto-acetic acid, 334
ester, 338
benzoic acids, 764
butyric acid, 344
chlorhydrose, 504
imido- ether, 292
lactic acid, 358
malonic acid, 342, 435
propionic acid, 340
succinic acid, 436
thienone, 534
Acetol, 321
Acetone, 203
bases, 208
chloride, loi
chloroform, 202
dicarboxylic acid, 435
homologues, 209, 210
Acetonic acid, 363
Acetonitrile, 283
Acetonyl acetone, 328

urea, 293
Acetophenone, 341, 727
acetone, 731
alcohol, 712
carboxylic acid, 764
chloride, 728
Acetoxime, 205
Acetoximes, 202

85

Acetoximic acids, 203, 207, 325
Aceturic acid, 371
Acetyl acetone, 327
aldehyde, 323
bromide, 247
carbinol, 321

carboxylic acid, 332

chloride, 247

cyanide, 248

iodide, 247

oxide, 247

peroxide, 250

sulphide, 251
Acetylene, 86, 88 ,

bromide, 89

chloride, 88

di-chloride, 90

iodide, 89

dicarboxylic acid, 43 1

naphthalene, 910

series, 88

telracarboxylic acid, 481

urea, 440
Acid amides, 255, 365, 214

anhydrides, 213, 248

chlorides, 246

cyanides, 247

haloids, 246

yellow, 648
Acidoximes, 292, 735
Aconic acid, 470
Aconitic acid, 472
Acridic acid, 973
Acridines, 603, 981
Acrite, 506
Acrolein, 199
Acrylaldehyde = acrolein
Acrylic acid, 233, 236

derivatives, 237
Adenine, 449
Adipic acid, 418
^sculetin, 822

1017

ioi8

INDEX.

^sculin, 1008
Alanine, 366, 371
Albumen, 1014
Albuminates, 1013
Alcarsine, 173
Alcoholates, 126
Alcohols, 112, 124, 708

anhydrides, 351

formation of, 119, 120, 121

primary, 117

secondary, 118

tertiary, n8
Aldehyde, 186, 187, 714

acids, 329, 761

alcohols, 320

ammonia, 189, 193

green, 868, 874

ketones, 730

phenols, 715
Aldehydine bases, 628, 718, 943
Aldines, 954
Aldol, 321

condensation, 195
Aldoses, 498
Aldoximes, 191

Alicyclic = aliphatic = ac. al. 912
Alizarine, 898

blue, 899, 975
Alkaloids, 991
Alkali green, 869
Alkamines, 315
Alkines, 315, 943
Alkyl fluorides, 94

Orfa chloride, 376
-AU:ylenes, 79

oxide, 300
Alkylogens, 93
Allantoiin, 440
AUanturic acid, 440
AUophanic acid, 393
Alloxan, 443
AUoxantine, 344
AUyl, 89

acetic acid, 241

alcohol, 134

aniline, 602

bromide, 98

chloride, 98

cyanide, 285

ether, 140

haloids, 98

malonic acid, 430

mustard oil, 281
Allylene, 89

AUylene, isomeric, 89
AUylin, 457
Aloes, 1009
Aloin, 1009
Aloetic acid, loio
Alorcinic acid, loio
Alphatoluic acid, 753
Aluminium methyl, 182

ethyl, 182
Amalic acid, 444
Amarine, 935
Amber, 1008
Amethyst, 990
Amic acids, 365, 402
Amide chlorides, 258
Amides, 255, 366
Amidines, 258, 293, 620
Amido-azobenzene, 647

acetic acid, 369

acids, 365

compounds, 591

dtcyanic acid, 290

formic acid, 382

glutaric acid, 467
"phenols, 679

phenyl-glyoxylic acid, 762

thiophenols, 681
Amidoximes, 294, 736
Amines, 157, 311

primary, 162

secondary, 163

tertiary, 164
Ammelide, 290
Ammeline, 290
Ammon-chelidonic acid, 948
Ammonium bases, 165
Amygdalin, 717
Amygdalic acid, 717
Amyl alcohols, 129

aldehydes, 198

benzene, 578
Amylenes, 84
Amylum, 512
Anethol, 803
Angelic acid, 240
Anhydrides, of acids, 248, 315
Anhydridic acids, 351
Anhydro bases, 627
Anhydroecgonine, 953, 997
Anilides, 599, 606
Anilido acids, 608
Aniline, 595

black, 991

blue, 874

Missing Page

IO20

INDEX.

Benzamide, 743
Benzamine, 710
Benzamidine, 736
j Benzam oxalic acid, 749
Benzanilide, 744
Benzaurine, 877
Benzazole compounds, 841
fi Benzazurine, 846
Benzeines, 876
Benzene, 571

additive products, 567

amido-compounds, 591

azom ethane, 652

derivatives, 556

formation of, 565

diazimide, 639

disulplioxide, 662

haloids, 579, 581, 582, 583

homologues, 557

hydrides, 571

hydrocarbons, 568

isomerides, 559
Benzene-nitro, 586, 587, 589

nitroso, 591

nucleus, 563, 564

phenols, 557

sulphonic acid, 661
Benzenyl amidines, 735

amidoximes, 735, 737
1 azoxime, 737
Benzhydrazoine, 650
Benz^;„^f-benzoic acid, 863
Benzhydrol, 857
benzhydroxamic acid, 746
Ben?hydroximic acid, 737
Benzidine, 650, 844
! dyes, 84s
JSenzil, 888
' oximes, 888
Penzilic acid, 862
Kenzimido ethers, 735
Benzoglyoxalines, 841, 842
Benzoic acid, 742

homologues, 753
substitution products, 746, 747,

748
sulphinide, 752
Benzoin, 887
Benzo-nitrile, 733
Benzo-phenone, 858

phenoxime, 858
Benzopyrazole, 841
Benzoquinone, 704
Benzoquinolines, 969

Benzothiazole, 6S1, 842
Benzotriairines, 957
Benzoxaziues, 981
Benzoxazole, 679, 680, 842
Benzoximido ethers, 736
Benzoyl acetic acid, 763

aceto-acetic ester, 763
carboxylic acid, 764

acetone, 731

acetyl, 731

acrylic acid, 816

aldehyde, 730

azimide, 640

benzoic acids, 863

carbinol, 712

chloride, 743

cyanide, 743

formic acid, 762

gly collie acid, 745

hydrazine, 745

phenols, 860

propionic acid, 764
Benzoylene urea, 978
Beuzpinacone, 889
Benzyl acetone, 730

alcohol, 709

amines, 710

anilines, 711

benzoic acid, 863

chloride, 584

cyanide, 734

glycollic acid 776

hydroxy lamines, 711

malonic acid, 791

mercaptan, 710

methyl ketone, 779

sulphide, 710

sulphydrate, 710

toluene, 862
Benzylidene aceto-acetic ester, 816

acetone, 805

aniline, 718

hydrazine, 718

malonic acid, 823
Berberine, 949
Berberonic acid, 949
Beryllium ethide, 179
Betaine, J16
Betaorcinol, 694
Biazolons, 936
Bidesyl, 892
Bieberich scarlets, 651
Biliary substances, loii
Bilineurine = choline

INDEX.

I02I

Bilirubin, ion
Biliverdin, ion
Bioses, 507

Bisdiazo-compounds, 639
Bismuth ethide, 185
Bitter almond oil, 716

principles, 1009
Biuret, 393
Boric esters, 1 55
Borneo!, 1006
Bornylamine, 1 005
Boron compounds, 175
Brasilin, loio
Brassylic acid, 423
Brilliant green, 868, 869
Bromal, 196
Bromanil, 701
Bromoform, 103
Bromopicrin, 113
Brucine, 995
Butanes, 74

chlorides, 94

nitro-, 108
Butyl alcohols, 128

amine, 163

chloral, 197
Butylene, 84

glycols, 309
Butyraldehydes, 197
Butyramide, 259
Butyric anhydride, 249

acids, 226, 227

esters, 254
Butyro-carboxylic acid, 348
Bulyrolactone, 362
Butyrone, 210
Butyronitrile, 2S4
Butyryl chloride, 247

cyanide, 248

C.

Cacodylic acid, 173

compounds, 172
Cadaverine, 313, 316
Caflfelc acid, 821
Caffeine, 449
Caffuric acid, 450
Car,iphene, looi
Camphol = borneol, 1006
Campholic acid, 1007

Camphor, 1004
Camphoraldehyde, looj
Camphoric acid, 1007
Camphoronic acid, 1007
Camphorpxime, 1005

chlorides, 1005
Camphylamine, 1005
Campo-bello yellow, 916
Cane sugar, 508
Cantharidin, lolo
Caoutchouc, 1008
Capric acid, 231

aldehyde, 1 98
Caproic acid, 229
Caprolactone, 364
Caprone, 210
Caproyl alcohols, 132
Capryl alcohol, see Octyl alcohols
Caprylic acid, 230
Caprylone, 210
Caramel, 509
Carbamic acid, 382
Carbamides, 386
Carbanile, 612
Carbanilamide, 612
Carbanilic acids 61 2
Carbanilide, 6n
Carbazol, 847
Carbdiamide-imide, 294
Carbimide, 384
Carbinol, 130
Carbizines, phenyl, 935
Carbodiimide, 288
Carbodiphenylimide, 620
Carbohydrates, 497
Carbon disulphide, 379

oxysulphide, 378

tetrachloride, 1104
Carbonic acid, 353, 375
Carbonyl amidophenol, 680

chloride, 375

diacetic acid, 959 \

diurea, 394
Carbopyrotritartaric acid, 528
Carbopyrrolic acid, 546
Carbostyril, 755, 968

carboxylic acid, 973 1

Carbostyrilic acid, 745
Carbothialdine, 385
Carboxyl, 211
Carboxy-tartronic acid, 480
Carbylamines, 287
Carbyl sulphate, 319
Carmine, ion

INDEX.

Caiminic acid, loil
Carnine, 449
Carthamine, loio
Carvacrol, 687
Carvene, looi
Carvol, 688
Caryophyllin, 1006
Casein, 1015
Cassia oil, 805
Catechin, 780, 785
Catechu tannin, 785
Cedriret, 848
Cellulose, 514

nitro, 514
Ceresine, 78
Cerotene, 86
Carotin, 134
Cerotic acid, 233
Ceryl alcohol, 134
Cetene, 86
Cetyl acetic acid, 233

alcohol, 133

raalonic acid, 423
Cevadine, 998
Chavibetol, 803
Chavicol, 803
Chelidamic acid, 948
Chelidonic acid, 958
Chitine, 10 12
ChloraCetol, loi

methyl, loi
Chipral, 196

Chloralides, 360 v

Chloranil, 701
Chlorauilic acid, 701
Chlorbenzil, 889
Chlorcarbonic acid, 376
Chlor-cyanogen, 267
Chlor-ethyl benzenes, 586
•'Chlorhydrins, 300, 456
Chlorformic acid, 219"" ~
Chloric acid esters, 155
Chlorimides, 258
Chloroform, 102
Chlorophyll, ion
Chloropicrin, 113
Chloroxalic ester, 406
Chlorphenyl mustard oil, 682
Cholesterine, ion

iso-, ion
Cholestrophane, 439
Cholalic acid, 1012
Cholic acid, 1012
ClioUne, 315

Chondrin 1012

Chromic acid mixture, 203, 738

Chrysamine, 846

Chrysammic acid, 900

Chrysaniline, 983

Chrysanisic acid, 750

Chrysarobin, 901

Chrysazin, 900

Chrysazol, 896

Chrysene, 928

perhydride, 929
Chrysoine, 651
Chrysoidines, 643, 648
Chrysoketone, 929
Chrysolin, 883
Chrysophanic acid, 901
Chrysophenol, 983
Chrysoquinone, 928
Cinchene, 995
Cinchomeronic acid, 948
Cinchonidine, 994
Cinchonine, 994
Cinchoninic acid, 972
Cinene, 1002
Cineols, 1006
Cinnamein, 809
Cinnamic acid, 808

alio-, 813

amido-, 811, 812

brom-, 810

chlor-, 809

di-, 813

hydro-, 812

nitro-, 810, 811
aldehyde, 805
Cinnaraenyl acrylic acid, 816
Cinnamone, 806
Cinnamyl alcohol, 804

formic acid, 816
Cinnoline, 976
Citraconic acid, 429
Citraconanile, 5i 1
Citramide, 481
Citramalic acid, 468
Citrene, looi
Citric acid, 480
Cocaine, 996
Cochineal, ion
Codeine, 992
Coeroulignone, 848
Coerulin, 883
CoUidine, 943

diparboxylic acid, 949
Collodion, 514

INDEX.

1023

Colophene, 1003

5 Colophony, 1008

Comanic acid, 958

Comenamic acid, 959

Comenic acid, 959

Compound ureas, 388

Condensation, 88, 195, 208, 335, 566

Congo red, 846
yellow, 847

jConhydrine, 952

IConiferine, 725

Coniferyl alcohol, 725

Conine, 952

I benzoyl, 952

Convolvulin, 1009
k Conylene, 952
f Conyrine, 944

Corindine, 937

Cotarnic acid, 993
I'Cotarnine, 993
|'*0)tarnine-hydro-, 993

Coumalic acid, 958

Coumaric acid, 818

Coumarilic acid, 826

Coumarin, 817, 819

Coumarinic acid, 819
i'Coumarone, 825

Coumazone compounds, 778

Creasote, 669

Creatine, 398
I Creatinine, 398

Creosol, 693

Cresols, 685

Cresorcin, 693
^'Cresotinic acids, 771

Crocein, 651

Croconic acid, 521, 703

Croton aldehyde, 199

Croton-chloral, 200

Croton oil, 241

Crotonic acid derivatives, 239

Crotonic acids, 233, 238

Crotonylene, 89

Crotoyl alcohol, 135

Ciyptidine, 960
i Crystal violet, 875

Cumene, 575

Cumenol, 687

Cumic acids, 760

^ aldehyde, 722

jCumidines, 624

^ Cumin alcohol, 711

oil, 688

Cuminil, 889

Cuminoin, 887

Cuminol=cumic aldehyde, 722
Cumylic acid=durylic acid, 760
Curara, 316
Curcumin, loio
Cyammelide, 271
Cyanalkines, 955
Cyanamines, 984
Cyan-acetic acid, 262

-amide, 288

-anilide, 620

-benzoic acids, 752

-carbonic acid, 295

-chloride, 267

-Conine, 956

-ethine, 956

-etholins, 275

-formic acid, 262

■hydrin, 717

-iodide, 268

-methine, 956

-phenine, 734

-propionic acid, 263

-sulphide, 278

-toluenes, 734
Cyanic acid, 271

esters, 273
Cyanides, metallic, 269
Cyanine, 966
Cyanogen, 264
Cyanuric acid, 272
amide, 290

esters, 275
Cymenes, 577
Cystein, 360
Cystin, 360

D.

Dahlia, 873
Daphnetin, 822
Daphnin, 823, 1008
Daturin = atropin, 996
Decane, 76
Decyl alcohol, 133
Decylenic acid, 242
Dehydracetic acid, 337, 957
Dehydrofichtelite, 927
Dehydromucic acid, 528
Desoxalic acid, 485
Desoxybenzoin, 887
Dextrine, 513

1024

INDEX.

Dextrose, 503

Diacetamide, 259

Diacetic acid. See Aceto-acelic acid.

Diaceto-acetic ester, 437

-succinic acid, 437

-analogues, 438
Diacetonamine, 208
Diacetone alcohol, 208, 322
Diacetyl, 326
Diacetylene, 90

-dimethyl, 90

-dicarboxylic acids, 432
Dialdan, 321
Dialdehydes, 324
Diallyl, 89 •

-acetic acid, 245

malonic acid, 430
Dialuramide, 441
Dialuric acid, 442
Diamido-benzenes, 625, 648
Diamido-toluenes, 626
Diamidottiphenyl methanes, 867
Diamines, 311
Diamylene, 85
Diastase, 508
Diaterebic acid, 469
Diaterpenylic acid, 470
Diazimido compounds, 639
Diazines, 953

benzo-, 976
Diazo-acetamide, 374

acids, 373
Di^zoamidobenzene, 637
Diazoamido- compounds, 631

benzene nitrate, 636
Diazobenzoic acids, 751
Diazo-compounds, 629
Dibenzoyl, 888

acetic acid, 891

methane, 891

succinic acid, 892
Dibenzyl, 884

carboxylic acids, 889

glycollic acid, 891
Dicarbon tetracarboxylic acid, 482
Dichlorhydrin,5, 455
Dicyanogen, 264 *
Dicyanamide, 289
Dicyandiamide, 289
Dicyandiamidine, 289
Diethyl, 74
Digaliic acid, 784
Diglycolamidic acid, 371
Diglycollic acid, 356

Dihydrobenzene, 717
Dihydropyrrol, 549
Di-indogen, 833
Diisatogen, 834
Diketones, 325, 327
Diketo-hexamethylene, 701
Diketon-monocarboxylic ester, 341
Dilactic acid, 359
Dilituric acid, 441
Dimethyl, 74
Dimethyl-acrylic acid, 241

aniline, 601

fumaric acid, 430

glyoxim, 207,326

-methylene chloride, loi

-phenylene green, 708
Dinicotinic acid, 948
Dinitro aceto-nitrile, 286
Dinitroparaflins, III
Dioxindol, 834
Dioxybenzophenone, 860
Dioxybutyric acid, 461
Dioxymalonic acid, 475
Dioxysuccinic acid, 475
Dioxytartaric acid, 491
Dipentene, 1002
Diphenacyl,89i
Diphenic acid, 849
Diphenine, 650
Diphenols, 848
Diphenyl, 843

acetic acid, 861

acetylene, 886

amido-derivatives, 844, 845

benzene, 852

carbinol, 857

carboxylic acids, 849

dicarboxylic acids, 849, 850

ethane, 861, 864

ethylene, 861, 885

glycollic acid, 862

guanidine, 619

imide, 847

ketone, 858

methane, 852, 856

phthalide, 880

succinic acid, 890

thiohydantoin, 618

thiurea, 616

tolyl methanes, 866

urea, 611
Diphenylamine, 603

blue, 603

dyes, 605

I025

Diphenylene acetic acid, 851

derivatives, 850

glycol lie acid, 851

ketone, 851

carboxylic acids, 852
oxide, 860

oxide, 848

methane, 847
, Diphenylin, 845
Diphenylol, 847
Diphthalyl, 787, 890

acid, 890

dicarboxylic acids, 793, 794

Dipicolinic acid, 948

, Dipiperidyls, 95 1

■ Dipropargyl, 90

Dipyridine, 942

Dipyridyl, 942

carboxylic acid, 950
Disaccharides, 507
Disazo-compounds, 645
Disulphanilic acid, 665
Disulphoxides, 154
Dithienyl, 536
Dithiocarbam'C acid, 614
Dithiocarbonic acid, 380
Dithiourethanes, 385
Ditolyl, 844
Ditolylamine, 624

ethane, 863

ketone, 863

methane, 863
Ditolylin, 845
Diureldes, 736
Duboisine, 996
Dulcitol, 488
Durenes, 576
Durenol, 760
Durylic acid, 760
iso, 760
Dynamite, 454

Ecgonine, 997

benzoyl, 997
Elaidic acid, 243
EUagic acid, 783
Emerald green, 686
Emodin, 901
Emulsin, 508
Eosin, 883
Epichlorhydrin, 456

Epicyanhydrin, 456
Epihydrin carboxylic acid, 456
Erucic acid, 243
Erythrin, 781
Erythrite, 474
Erythritic acid, 474
Erythro-oxyanthraquinone, 898.
Esters, 137, 146, 148, 150, 151, 251

anhydrides, 351
Ethane, 74

perbromide, 105

perchloride, 105
Ethanes, 70
Ethenyl amidine, 294 , 620

amido-phenol, 683

tricarboxylic acid, 471
Ethers, compound, 137

mixed, 136

simple, 136
Ether 'acids, 146
Ethereal oils, 998
Ethidene compounds, 305

chloride, 100

dimalonic acid, 481

lactic acid, 356

sulphonic acids, 320
Ethine diphthalyl, 824
Ethionic acid, 319
Ethyl. See Diiriethyl

aceto-acetic ester, 338

alcohol, 125

aldoxime, 194

amine, 163

benzoic acids, 757

bromide, 94

carbonic acid, 377

chloride, 93

cyanide, 284

cyancarbonic ester, 377

diazoacetate, 374

ether, 138

hydride. See Ethane.

iodide, 96

nitrite, 148

orange, 651

sulphide, 143

sulphonic acid, 153
Ethylene, 79, 82

acetamidine, 313

bromide, ^ / 0^

chloride, 97, 100

cyanide, 303

diamine, 312

dibromides, g'7

86

I026

INDEX.

Ethylene dichlorides, 97

di- iodides, 97

glycol, 301

lactic acid, 361

oxide, 303

sulphide, 303

sulphonic acids, 317
Ethylidene chloride, 100

bromide, 100

iodide, loi
Euchroic acid, 799
Eugenol, 803
Eupittonic acid, 879
Eurhodines, 986
Eurhodols, 988
Euthiochronic acid, 692
Euxanthinic acid, loio
Euxanthone, 860
Everninic acid, 782

F.

Fats, 4S9

Fatty acids, 211, 215

compounds, 68, 69
Fermentation, 503
Ferulic acid, 821
iso, 821
Fibrin, 1015
Fichteiite, 927
Flavaniline, 971
Flavenol, 971
Flavol, 896
Flavophenine, 846
Flavopurpurine, 900
Fluoranthene, 927
Fluoranthraquinone, 927
Fluorbenzene, 583
Fluorbenzoic acid, 747
Fluorene, 850
Fluorene alcohol, 851
Fluorenic acid, 851
Fluorescein, 882
Fluorescin, 883
Fluorindene, 991
Formal, 301

Formamide, 259*^ ^ .,
Formamidine, 293
Formanilide, 606
Forn ic acid, 216

aldehyde, 191

Formic esters, 253
Formoimido-ethers, 292
Formonitrile, 283
Formose, 499
Formyl acetic acid, 331

acetone, 323

tricarboxylic acid, 471
Fructose, 505

Fructose carboxylic acid, 496
Fruit sugar, 505
Fuchsine, 872
I'ulminic acid, 285
Fulminuric acid, 286
Fumaric acid, 425
Furfurane, 521, 523

acids, 526, 527, 528

alcohols, 524

alkylic, 523

amides, 525

G.

Gaidinic adid, 242
Galactose, 506
Gallacetophenone, 729
Gallein, 883
Gallesiine, 50
Gallic acid, 782
Gallin, 883

Gallocarboxylic acid, 796
Gallocyanine, 984
Gallylgallic acid, 785
Garancin, 898
Gaultheria procumbens, 767
Gelatines, 1012
Gentisin, loii
Gentisinic acid, 778
aldehyde, 724
Germanium ethide, 183
Gluconic acid, 489
Glucosamine, 505
Glucosazone, 501, S°4
Glucose carboxylic acid, 495
Glucoses, 497, 502, 503
Glucosides, 502, 1008
Glucosine, 325
Glucosone, 505
Glutaconic acid, 428
Glutamin, 467
Glutaminic acid, 467

INDEX.

ICO29

iGlutaric acid, 417
gluten, 1015
iGlutin, 1012
iGlutinic acid, 432
JGIyceric acid, 460
Klycerides, 458
■Glycerol, 452
I ethers, 454
I Glyceryl bromide, 104

chloride, 104
I iodide, 104
■Glycide compounds, 456
iGlycidic acid, 457
I'Glycine or glycocoll, 369

Glycocholic acid, loii
^ Glycocoll, 369
f anhydride, 370
• Glycocollamide, 370

Glycocyamine, 397

Glycogen, 513

Glycolide, 356

GlycoUic acid, 354

derivatives, 354
alcohol, 355
anhydride, 356

Glycol mercaptan, 303

Glycols, 296, 297

Glycoluric acid, 392

Glycolyl, 353

aldehyde, 321
-phenyl urea, 612
urea, 391

Glycouril, 440

Glycovanillin, 725

Glycuronic acid, 491

Glyoxal, 324
ethylin, 552

Glyoxalic acid=Glyoxylic acid , 330

Glyoxalin, 325, 326, 551,552

Glyoxalines, phenylated, 934

Glyoximes, 324, 325

Glyoxyl urea, 440

Glyoxylic acid, 330

Grape sugar, 503, 504

Guaiacol, 690

Guanamines, 296

Guanidines, 294, 397

Guanine, 448

(Juanyl urea, 289

Guinea green, 869

Gum resins, 1008

Gums, 513

Gun cotton, 515

Gutta percha, 1008

H.

Hsematin, loi6
Haematoxylin, loio
Hsemin, 1016
HEemoglobin, 1015
Halogen esters, 299
Haloid anhydrides, 213, 246
Helianthine, 651
Hehcin, 713
Heliotropine, 804
Helvetia green, S69
Hemimellithene, 575
Hemimellitic acid, 797
Hemipinic acid, 793
Heptamethylene, 521
Heptanes, 75
Heptoic acids, 230
Heptolactone, 365
Heptoses, 507
Heptyl alcohols, 133
Heracleum oil, 133
Herapathite, 994
Hesperidin, looi, 1009
Hesperitic acid, 821
Hexamethyl benzene, 579
Hexamethylene, 521
Hexamethylene amine, 193
Hexanes, 75
Hexaoxydiphenyl, 498
Hexoic acids, 229
Hexoses, 498
Hexoylene, 89
Hexyl alcohols, 132
Hipparaffin, 745
Hippuric acid, 744
Homatropine, 996
Homophthalimide, 791
Homoprotocatechuic acid, 780
Homopyrocatechin, 693
Homopyrrols, 542
Homovanillic acid, 780
Hysenic acid, 215
Hydantoic acid, 392
Hydantoin, 391, 392
Hydracrylic acid, 36 1
Hydramines, 314
Hydranthranol, 895
Hydrazines, 166,653

alkylized, 657
Hydrazo-benzene, 649

-benzoic acid, 751
Hydrazoic acid, 640
Hydrazones, 500

I°/2'8

INDEX.

Hydrazoximes, 326
Hydrindene, 902, 903
Hydrindic acid, 773
Hydrindone, 904
Hydrindo-naphtbene, g02
Hydroatropic acid, 759
Hydrobenzamide, 717
Hydrobenzoin, 886
HydrocafFeic acid, 782
Hydrocarbostyril, 755, 758, 968
Hydrocinnamide, 805
Hydrocinnamic acid, 757
Hydrocoerouglinone, 844
Hydrocornicularic acid, 892
Hydrocoumaric acid, 782
Hydrocoumarin, 774
Hydroferulic acid, 782
Hydroflavic acid, 265
Hydrojuglones, 918
Hydromellitic acids, 800
Hydromuconic acid, 430
Hydronaphthoquinones, 918
Hydronaphthylamines, 91 1
Hydrophlorol, 694
Hydrophthalic acids, 778
Hydrophthalide, 772
Hydropicolines, 95 1
Hydropiperic acid, 822
Hydroquinone, 691
Hydroquinone carboxylic acid, 778
Hydrorubianic acid, 265
Hydrosorbic acid, 245
Hydroterephthalic acid, 790
Hydroumbellic acid, 782
Hydroxamic acids, 260
Hydroxylamine derivatives, 166
Hydroxyurea, 388
Hydurilic acid, 445
Hyoscine, 996
Hyoscyamine, 996
Hypogseic acid, 242
Hypoxanthine = sarcine, 449
Hystazarine, goo

Idryl, 927
Imesatin, 835
Imide chlorides, 258
Imides, 365
Imido-carbonic acid, 384

-ethers, 292, 735

-thio-carbouic acids, 386

Imido-thio-ethers, 293
Indazol, 812, 841
Indene, 902
Indican, 839
Indigo, 837, 839

carmine, 840

purpurine, 840
Indigotin, 837

white, 840
Indin, 840
Indirubin, 833, 840
Indoanilines, 705, 707
Indoamines, 705, 708
Indogenides, 833
Indoin, 834
Indol, 827
Indophenin, 835
Indophenols, 705, 707
Indoxanthic ester, 833
Indoxyl, 832
Indoxylic acid, 832
Indulines, 648, 990
Inosite, 697
Inuline, 512
Invert sugar, 505
Iodine, green, 874
Iodoform, 103
lodol, 541
Ipomic acid, 1009
Iridolin, 960
Isatin, 834

chloride, 836
Isatinic acid, 762
Isatogenic ester, 834
Isatoxime, 837
Isatropic acid, 813
Isatid, 83s
Isethionic acid, 318
Isindazole, 841
Isobenzil, 889
Isobutyric acid, 227
Isobutyryl chloride, 247
Isocaprolactone, 364
Isocholine, 316
Isocinchomeronic acid, 948
Isocyanic acid, 27 1
Isocyanides, 287
Isocyanuric acid, 272
Isodiphenic acid, 850
Isodulcitol, 483
Isoferulic acid, 821
Isoglucosamine, 505
Isohydrobenzoin, 886
Isoindol, 955

INDEX.

1029

Isonicotine, 953
Isonicotinic acid, 946
Isonitroso-acetic acids, 222

-acetone, 206

acetophenoDe, 728
' acids, 214

compounds, 106
Iso-orcin, 693
Isophthaiic acid, 788
Isoprene, 1002
Isopropyl alcohol, 127

bromide, 95

chloride, 94

iodide, 96
Isopurpuric acid, 678
Isoquinoline, 975
Isosaccharic acid, 494
Isosaccharin, 484
Isosafrol, 804
Isosuccinic acid, 416
Isothio-acetamide, 260, 5o8

-cyanic acid, 277

-ureas, O17
Isouvitic acid, 790
Isovaleramide, 259
Isovaleryl chloride, 247
Isovanillic acid, 780
Isovanillin, 726
Isuret, 294, 388
Itaconic acid, 429
Itamalic acid, 468

Jalapin, 1009
Juglone, 919
-oxy, 919

K

Kairine, 967

Kairoline, 966

Kanarine, 278

Kerosene, 77

Ketines, 207, 954, 9S5

Ketipic acid, 437

Ketoamines, 112

Ketol, 830

Ketone alcohols, 321
aldehydes, 323
decomposition, 337
dicarboxylic acids, 432

Ketones, 186, 200, 726

Ketonic acids, 331, 333, 343, 761, 763

Ketopentene, 521

Ketoses, 498

Ketoximes, 202, 325

Kino-tannin, 785

Kynurenic acid, 973

Kynuric acid, 973

Kynurine, 969

Lactams, 755
Lactamides, 366
I/actic acids, 356
Lactides, 351, 358, 359
Lactimides, 366
Lactims, 755
Lactones, 351, 352
Lactonic acid, 491

acids, 462
Lactose, 506, 509
Lacturic acid, 393
Lactyl chloride, 358

urea, 392
Laavomannitol, 487
Lasvulinic acid, 343
Lsevulose, 505
Lanoline, loil
I^auramide, 259
Laurie aldehyde, 198

acid, 232
Laurone, 210
Lauth's violet, 604
Lead compounds, 1S5
Lead plaster, 231
Lecanoric acid, 781
Lecithin, 10:5, 1016
Legumin, 1015
Lekene, 79
Lepargylic acid, 423
Lepidine, 968, 969, 970
Leucaniline, 87 1
Leucaurine, 878
Leucaurolic acids, 1 10
Leucic acid, 364
Leucine, 373
Leucoline, 960
Leucomalachite green, 867
Leuconic acid, 521, 703
Leucorosolic acid, 878
Leucoturic acid, 444

I030

INDEX.

Leucoviolet, 875
X>ichinine, 5'2
Ligroine, 77
Limonene, looi
Linoleic acid, 243
Litmus, 693
Lophine, 934
Lupetidines, 95 1
Luteoline, 780
Lutidines, 943
Lutidinic acid, 948
Lutidones, 945
Lycine, 316

M

Maclurin, 780
Magdala red, 990
Magenta, 872
Magnesium-ethide, 179
Malachite green, 867
Malamide, 466
Maleic acid, 425, 426.'
Malic acid, 464
Malon-anilic acid, 610
Malonic acid, 408
Malonitrile, 409
Malonyl aldehyde, 325

urea, 441
Maltose, 510
Mandarin yellow, 916
Mandelic acid, 772
Mannide, 487
Mannitan, 487
Mannitic acid, 489
Mannitol, 487
Mannonic acids, 490
Mannononose, 507
Manno octose, 507.
Mannose, 503

carboxylic acid, 445
Margaric acid, 232
Marsh gas, 73
Mauvaniline, 990
Mauveine, 990
Meconine, 793
Meconic acid, 959
Meconinic acid, 793
Melane, 291
Melamine, 290

Melampyrine = Dulcitol, 488
Melanurenic acid, 291
Melebiose, 511

Melene, 291
Melezitose, 5 1 1
Melilotic acid, 774
Melissic acid, 233
Melissyl alcohol, 134
Melitose, 5 1 1
Mellimide, 799
Mellitic acid, 799
Mellon 292
Mellophanic acid, 799
Menthene, 1000, 1007
Menthol, 1006
Mercaptans, 140
Mercaptals, 142
Mercaptides, 142
Mercaptols, 142
Mercapturic acids, 360
Mercury allyl iodide, 182

-ethide, 182

raethide, 182
Mesacbnic acid, 429
Mesicerine, 714
Mesidic acid, 790
Mesidine, 624
Mesitylene, 208, 574

glycerol, 714
Mesilylenic acid, 756
Mesityl oxide, 208
Mesitylol, 687
Mesorcin, 694
Mesotartaric acid, 479
Mesoxalic acid, 434
Mesoxalyl urea, 443
Metadiazines, 955

-oxy, 956
,Metaldehyde, 194
Metallo-organic compounds, 177
Metasaccharic acid, 494
Metasaccharin, 484
Methacrylic acid, 193
Methane, 73

chlor, 105

iodo, 105
^ tetrabrom, 104
Methionic acid, 317
Methenyl amidine, 293

amido-thio-phenol, 614

amidoxime, 294
Methose, 499
Methronic acid, 528
Methylal, 301
Methyl aldehyde, 191

alcohol, 124
Methylamine, 162

INDEX.

I03I

Methyl aniline, 513

anthracene, 901

bromide, 94

chloride, gj

crotonic acid, 241

cyanide, 283

ethyl aceto-acetic ester, 340

glyoxal, 323

glyoxime, 207

indol, 830

iodide, 95

ketol, 32 r, 830

orange, 651

quinolinic acid, 949

sulphurane, 304

urabelliferon, 821

violet, 874
Methylene, 82

blue, 605

chloride, 100

derivatives, 301

red, 606
Methylenitan, 499
Milk sugar, 509
Mirbane oil, 587
Mixed azo-compounds, 653
Morin, 785
Moringa- tannin, 785
Morphine, 992
Morpholine, 315, 957
Mucedin, 1015
Mucic acid, 493
Mucilages, 513
Mucobromine acid, 427
Mucochloric acid, 428
Mucolactonic acid, 470
Muconic acid. 432, 470
Murexan, 441
Murexide, 445
Muscarine, 316
Mustard oil, 280
Mycose, 511
; Mydatoxime, 316
!• My dine, 316
i Myosin, 1015
Myricyl alcohol, 134
Myrisitic acid 232
Myristamide, 259
Myristic aldehyde, 198
Myristicol, 1006
Myristone, 210
Myronic acid, 281, 1009
Myrosine, 281, 1009
Mytilotoxine, 316

N

Naphanthracene, 929
Naphsultone, 916
Naphtha, 77
Naphthalene, 905, 908

alcohols, 921

amido-,910

azo-, 913

carboxylic acids, 922

haloids, 909

hydrides, 908

ketones, 921

nitriles, 921

nitro-, 910

phenol derivatives, 915, 916

red. 990

sulpho-acids, 914

yellow, 916
Naphthalic acid, 923
Naphthalidine = Naphthylamine
Naphthalizarin, 919
Naphthazine, 986
Naphthene, 78
Naphthindol, 923
Naphthionic acid, 915
Naphthofurfurane, 923
Naphthoic acid, 922
Naphthol, 915, 917

blue, 707, 919, 984

hydrides, 917

nitroso-, 920

sulphonic acids, 917
Naphthoquinone, 918, 919

chlorimide,9ig

hydrides, 919
Naphthoquinoximes, 920
Naphthostyril, 922
Naphthylamine, 910, 911
Naphthyl hydrazines, 914
Narceine, 993
Narcotine, 993
Neurine, 316
Neutral red, 988
Nicotidene, 953
Nicotine, 953
Nigrosine, 990
Nitranilic acid, 701
Nitriles, 282, 732
Nitroacetonitrile, 285
Nitro-amines, 106, 594
Nitrobenzene, 587
Nitrobutanes, 108
Nitrochloroform, 113

I032

Nitrococcic acid, 771
Nitro-compounds, 105, 586
Nitroethane, 108
Nitroform, 112
' Nitroglycerol, 454
Nitrolamines, 1 12, 998
Nitrolic acids, 109, 1 10, 646
Nitromethane, 107
Nitroparafifins, 107
Nitrophenols, 676
Nitropropane, 108
Nitropropionic acid, 180
Nitroprussides, 270
Nitrosates, 1 1 1
Nitrosites, III, 999
Nitroso-compounds, 106
iso-, 106, 591

-indoxyl, 833

naphthbls, 920
\ _ phenol, 675
Nitrotoluenes, 590
Nonane, 76
Nonoic acid, 230
Nonoses, 507
Nonylenic acid, 242
Norhydrotropine, 953
Noropianic acid, 793

O

Octane, 75

Octodecyl alcohol, 133

Octoic acid, 230

Octoses, 507

Octyl alcohol, 133

QLnanthol, 198

CEnanthone, 210

CEnanthylic alcohol, 133
acid, 230

Oils, drying, 243, 453
fatty, 243, 453

Olefiant gas, 82

Olefines, 79

formation of, 79, 80
higher, 85, 86
oxidation, 82
polymerization, 82

Oleic acids, 233, 242

Opianic acid, 793

Opium, 992

Orcein, 692

Orcin, 6^2

Organo-metallic compounds, 177
Orsellinic acid, 781
Ortho-carbonic ester 473
Orthoformic ester, 452"
Osazones, 326, 502
Osones, 501
Osotetrazones, 326
Osotriazones, 326, 553
Oxalan, 440
Oxalan'tin, 444
Oxalethylin, 552

Oxalic acid, 403 ^ ^

Oxalines, 552 ' V^
Oxalmethylin^407, 552
Oxalo-acelic acid, 435
Oxaluric acid, 439
Oxalyl urea, 439
Oxamethane, 407
Oxamic acid, 407
Oxamide, 406 ^,- '
Oxamidine, 294
Oxaraidines, 294, 736
Oxanilic acid, 610
Oxanilide, 610
Oxanthranol, 896
Oxatolic acid, 891
Oxazine, 957
Oximes = aldoximes.
Oximido-compounds, 106

esters, 735
Oxindol, 831
Oxyacids, 345, 353
anhydrides, 35 1

primary, 350

secondary, 350
OxyacryHc acids, 365
Oxyalcohols, 7,13
Oxyangelic acids, 365
Oxyanthraquinones, 897
Oxybenzoic acid, 767
Oxybenzo-phenones, S60
Oxybutyric acids, 362, 363
Oxycaproic acids, 364
Oxychrysazinej. goo
Oxycinchoninic acid, 973
Oxycinnamic acids, 818
Oxycitric acid, 486
Oxycoiimarin, 821
Oxycrotonic acids, 365
Oxycyanides, 190, 202, 347
Oxydtphenyl, 847
Oxyethyleiie bases, 314
Oxyformic acid, 353
Oxyglutaric acid, 467

INDEX.

1033

Oxymalonic acid, 463
Oxymethylbenzoic acids, 772
Oxymethylene, 192
Oxyneurine, 316
Qxyphenic acid, 689
Oxyplienyl acetic acid, 771
Oxyphthalic acid, 792
Oxyphthalophenone, 88l
Oxypiperidine, 951
Oxypropionic acids, 356
Oxypropylbenzoic acid, 777
Oxypyrimidines, 736
Oxyquinolines, 967
Oxyquinolinic acid, 948
Oxytetraldine, 321
Oxytoluic acids, 771
Oxyuvitic acid, 792
Oxyvaleric acids, 363, 364
Ozolcerite, 78

Palmitamide, 259
Palmitic acids, 232
aldehyde, 198
Palmitin, 458
Paltnitolic acid, 245
Palmilone, 210
Palmitoxylic acid, 245
Papaverioe, 993
Para-azoxine, 31 5
Parabanic acid, 439
Paraconine, 953
Paraconic acid, 468
Paracyanogen, 265
Paracymene, 577
Paradiazines, 954
''araff- '-^ 70, 76, 78
PropaWe,"74, 'vde, 192
,JPro£arg»l^Ict. 60
1 .iraiaeiiyi. r»ci<i
Paraldol, 321 '"^
Paraleucaniline, 869, 870
Param, 289
Paramide, 799
Paramylum, 512
Pararosaniline, 871

derivatives, 874
Parietic acid, see Chrysophanic acid
Parvoline, 937
Patchouly, 1006
Pelargonic acid, 230

Pentadecatoic acid, 232
Pentametliyl benzene, 578
Pentamethylene derivatives, 520
Pentane, 75
Pentaoxyhexane, 483
Penthiophene derivatives, 537
Pentinic acid, 345
Peonine, 878
Pepsine, 1014
Peppermint oil, 1006
Peptones, 1014
Perbromelhane, 105
Perchlormesole, 105
Perchlormethane, 105
Perchlorpyrocoll, 547
Perseite, 494
Peru balsam, 742
"Petroleum, 77
benzine, 77
ether, 77
Petrolic acids, 243
Phaseomannite = inosite, 697
Phellandrene, 1003
Phenacetolin, 670
Phenanthrene, 924

hydrides, 925
Phenanthrene carboxylic acids, 926
Phenanthraquinone, 925
Phenanthridine, 974
Phenanthroline, 975 •
Phenazine, 629, 980, 984, 986

tetramido derivatives, 987

triamido derivatives, 987
Phenetol, 670
Phenol, 666, 669

blue, 707

diazo compounds, 683

ethereal salts, 670

ethers, 670

homologues, 685 ^

phthalein, 882

sulphonic acids, 684

sulphuric acids, 685
Phenoquinone, 700
Phenose, 697
Phenoxazine, 983
Phenyl acetaldehyde, 721

acetic acid, 753

aceto-carboxylic acid, 790

acetone, 729

acetylene, 802

acrylic acids, 807, 813

alanine, 758

amidines, 450

I034

INDEX.

Phenyl benzoic acid, 849
butyro lactone, 777
carbonate, 670
carbylamine, 613
crotonic acid, 813
diacetylene, 803
dithio-carbamic acid, 614
ethers, 671/
ethylene, Sfcio
ethyl sulpoone, 662
glyceric aiid, 782
glycerol, 714
glycidic ^cid, 777
glycocoll, 608
glycocollic acid, 671, 772
glyoxyllic acid, 762
glyoxime, 728
guanidine, 619
hydantoin, 608
hydracrylic acid, 776
hydrazides, 489
hydrazine, 655
hydrazones, 656
imido butyric acid = phenylimido-

crotonic ester, 6og
indol, 830,831
isocyanates, 634
isocyanide, 613
itamalic acTa;~7g3
lactic acid, 776
malonic acid, 791
methyl ketone, 727
mustard oil, 614

glycoUide, 616
oxyacrylic acid, 777
pbenazonium, 989
phosphine, 621
paraconic acid, 793
phthalide, 863
propiolic acid, 814
amido, 815
nitro, 815
quinoline, 971
styceric acid, 782
succinic acids, 791
sulphaminic acid, 664
sulph-hydantoins, 619
sulphide, 672
sulphone, 663
thio-hydantoin, 6l8

urea, 5i6
thiurethanes, 615
tolyl, 843

methanes, 862

Phenyl urea, 612

urethanes, 612
Phenylene blue, 708

diamines, 625

methenyl amidine, 628, 842

ureas, 627
Phlorelic acid, 775
Phloretin, 1009
Phloridzin, 1009
Phloroglucin, 695

tricarboxylic acid, 797
Phloron, 704

Phoenicin- sulphuric acid, 840
Phorone, 208
Phosgene, 375
Phosphenyl chloride, 621
Phosphin, 983
Phosphines, 1 6 8, 317
Phosphinic acids, 156
Phospho-benzene, 451
Phosphonium bases, 1 70
Phosphoric acids, 155

esters, 155
Photogene, 78
Phthalanile, 611
Phthaleins, 881
Phthal-green, 883
Phthalic acid, 786

aldehydes, 722

anhydride, 787

chloride, 787
Phthalid, 772
Phthalide, 879
Phthalideins, 628
Phthalidins, 772, 882
Phthalimide, 787
Phthalimidine, 788
Phthalins, 882
Phthalophenone, 864, 8S0
Phthalyl acetic acid, 823

alcohol, 712 I-

hydroxamic acid, 78^63. ,._^
Phycite, 474 A '

Phytosterine, loii
Picamar, 696
Picene, 929
Picoline, 943

carboxylic acids, 947, 949
Picolinic acid, 947
Picramic acid, 683
Picramide, 598
Picric acid, 677
Picro-cyaminic acid, 678
Picroerytbrin, 781

INDEX.

I03S

Picrotoxin, loio
Picryl chloride, 590
Piraaric acid, 1 008
Pimelic acid, 421
Pinacones, 202, 310
Pinacolines, 202, 210
Pinacolyl alcohol, 131
Pinene, 999

dibromide, 1000

dichloride, 1000

hydrochloride, 1000

nitroso chloride, looo
Finite, 484, 697
Pinol, 1006
Pipecolines, 951
Piperazine, 955
Piperhydronic acid, 822
Piperic acid, 822
Piperideines, 952
Piperidine, 950

alkyl-, 951

benzoyl, 951

urethanes, 951
Piperine, 95 1
Piperonal, 726
Piperonyl alcohol, 714
Piperonylic acid, 780
Piperylene, 951
Pittical, 879

Pivalic acid = Trimethyl acetic acid
Polyglycerols, 459
Polyglycols, 304
Polymerization, 82, 190
Polymethylene compounds, 595
Polyquinoyls, 702
Polysaccharides, 512
Populin, 713

Porissic acid = Euxanthinic acid
Prehnitic acid, 798
Propalanine, 372
Propane, 74
Propargyl alcohol, 1 35
Propargylic acid, 244
Propenyl-benzoic acid, 778

tricarboxylic acid, 471
Propidene chloride, loi
Propiolic acid, 244
Propionamide,
Propione, 209
Propionic acid, 259

aldehyde, 197

anhydride, 222

esters, 254
Propionitrile, 284

Propionyl chloride, 247

cyanide, 248
Propiophenone, 729
Propio-propionic acid, 225
Propyl acetylene carbonic acid, 245

acetylene carbonic acid,iso-, 245

alcohols, 127

bromide, 94

chlorides, 93

iodide, q6
Propylamine, 163
Propylene, 79, 83

glycols, 308

haloids, 98, 102
Propylidene acetic acid, 241

chloride, loi

diacetic acid, 421
Protagon = Lecithin.
Protein substances, 1013
Protocatechuic acid, 779

aldehyde, 724
Prussic acid, 265
Pseudoaconitic acid, 473
Pseudocarbostyril, 968
Pseudocumene, 574
Pseudocyanogen sulphide, 278
Pseudoindoxyl, 833
Pseudoisatin, 834, 837
Pseudoisatoxime, 837
Pseudonitrols, no
Pseudopurpurin, 902
Ptomaines, 316, 1013
Pulvic acid, 892
Purpuric acid, 44S
Purpurin,90O
Purpur-oxanthin, 900
Putrescine, 313, 316
Pyrazine, 954, 980
Pyrazole, 551

phenylated,930

phenyl, 932
Pyrazoline, 551
Pyrazolidine, 551
Pyrazolon, isophenyl, 932

phenyl-methyl, 933

phenyl-dimethyl, 933
Pyrene, 928
Pyrenic acid, 928
Pyrenquinone, 928
Pyridine, 936,937,941

dicarboxylic acids, 947

monocarboxylic acids, 946

pentacarboxylic acids, 950

tetracarboxylic acids, 950

1036

INDEX.

Pyridine tricarboxylic acids, 949
fatty acids, 947
hexahydro-, 950
homologues, 942, 943, 944
hydrides, 950
isomerides, 941
oxy-derivatives, 944
phenyl, 944
Pyridones, 945
Pyrimidine, 95 S

oxy-, 956 fc,
Pyrocatechin, 689
Pyrocinchonic acid, 430
Pyrocomenic acid, 958
Pyrogallol, 694

carbonic acid, 562
Pyrogallic acid, 694
Pyroglutaminic acid, 467
Pyromecazonic acid, 946
Pyromeconic acid, 958
Pyromellitic acid, 798
Pyromucic acid, 526
Pyrone, 958

oxy-, 958

carboxylic acids, 958
Pyroracemic acid, 332
Pyrotartaric acid, 416
Pyroterebic acid, 241
Pyroxylin, 514
Pyrrocol, 547
Pyrrol, 521,539

alkylic derivatives, 540

azo-com pounds, 544

carbonyl-, 540

carboxylic acids, 545, 546, 547

cyan-, 540

dicarboxylic acids, 548

homologues, 542, 543

hydrides, 549

ketones, 544

ketonic acids, 548

tetraiodo-, 541
Pyrrolidine, 413

compounds, 550
Pyrollin, 549, 550
Pyruvic acid, 333
Pyruvil, 341

Quercite, 484, 697
Quercitin, 1009
Quercitrin, 1009
Quinacetophenone, 729

Quinaldinic acid, 972
Quinaldine, 969
nitro-, 970

oxy-, 970

tetrahydro-, 970

carboxylic acids, 973
Quinazole, 841
Quinazoline, 977

thio-, 978
Quinhydrone, 700
Quinic acid, 785
Quinene, 995
Quinine, 994
Quininic acid, 973
Quinisatin, 765
Quinisatinic acid, 765
Quinizarin, 900
Quinizine compounds, 930
Quint gens, 326
Quinoline, 936, 960, 965
" Tacrylic acid, 970

amido-, 967

betaine, 966

carboxylic acids, 972

chlor-, 966

dicarboxylic acids, 973

dihydro-, 966

dioxy-, 969

homologues, 969

methyl, 969

naphtho, 974

nitro ,966

oxy-, 967, 968

phenyl 971

red, 976

tetrahydro-, 966

trioxy-, 969

yellow, 970
Quinolinic acid, 947
Quinolyls, 966

di-, 966
Quinone, 326, 699

carboxylic acid, 796, 798

chlorimides, 705

phenolimide, 706
Quinophthalone, 970
Quinoxalines, 326, 978, 980
Quinoxime, 706

R

Racemic acid, 478
Radicals, 45, 70, 177, 213
Raffinose, 511

INDEX.

1037

Resacetophenone, 729

Resazurin, 691

Resins, 1008

Resocyamine = Methyl Umbelliferon,

822
Resorcin, 690
Resorcinol, 690

phthalein, 882
Resorcyl aldehyde, 724
Resorcylic acids, 778
Resoru6n, 691
Retene, 926
Rhamnose, 483

carboxylic acid, 491
Rheinic acid = Chrysophanic acid, 901
Rhodamines, 884
Rhodanic acid, 356
Rhodanides, 634
Rhodizonic acid, 702
Ricinelaidic acid, 244
Ricinoleic acid, 243
Roccellic acid, 423
Rocellin, 652, 917
Rock oil, 77
Roman oil of cumin, 240
Rosaniline, 870, 871

alkylic, 873, 874,87s, 876
Rosamines, 877
Roshydrazine, 876
Rosindulines, 991
Rosolic acids, 876, 878 .
Ruberythric acid, 898
Rubidine, 937
Rubine, 873
Rue, oil of, 210
Rufigallic acid, 783, 900
Rufiopin, 900
Rufol, 896

S

Saccharic acid, 484, 492
Saccharates, 502
Saccharin, 484, 752
Saccharon, 485
Saccharonic acid, 485
Saccharose, 508
Safflower, 10 10
Safranines, 989

pheno-, 989, 990

phenyl, 990

tola-, 990
Safranol, 990
Safrol, 804
Salicin, 713

Salicylic acid, 767

aldehyde, 723
Saligenin, 713
Saliretin, 713
Salol, 769
Santoic acid, loio
Santonin, 10 10
Saponin, 1009
Saponification, 253
Saprine, 316
Sarcine, 449
Sarcolactic acid, 360
Sarcosine, 370
Schweinfurt's green, 221
Sebacic acid, 423
Seignette salt, 371
Selenium compounds, 145
Serin, 461

Sesquiterpenes, 1003
Shellac, 1008
Skatole, 830
Silicic acid esters, 156 ,
Silicon-benzoic acids, 622
Silicon-ethide, 176
Silicononyl alcohol, 176
Silicopropionic acid, 177
Sinamine = AUylcyanide
Sinapic acid, 998
Sinapine, 998
Sinapoline, 390
Sincaline = Choline
Soaps, 231
Solar oil, 78
Sorbic acid, 245
Sorbine, 506
Sorbinose, 506
Sorbite, 488, 503
Sparteine, 992
Spermaceti, 255
Spermine, 955
Starch, 512
Stearamide, 259
Stearic acid, 232

aldehyde, 198
Stearin, 232
Stearoleic acid, 245
Stearone, 210
Stearoxylic acid, 245
Stibethyl, 175
Stibines, 174
Stilbazole, 943
Stilbene, 885

carboxylic acid, 890
Storax, 808

1038

INDEX.

Strychnine, 995
Stycerine, 714
Stypbnic acid, 678
Styracine, 808, 809
Styrene, 804
Styrolene, 800

alcohol, 7 1 2
Styryl alcohol, 804
Suberic acid, 422
Suberone, 422
|feuccinamic acid, 413
Succinamide, 412
Succinic acids, 410, 420, 421, 422

bromo-, 413, 414
Succino-succinic acid, 795
Succinyl aldehyde, 325^

aldoxime, 325
, Sugar, 503
Sulph, see also Thio,
Sulphamides, 752
Sulphamin-benzoic acid, 752
Sulphanilic acid, 664
Sulphimido-benzenes, 665
Sulphines, 144
Sulphinic acids, 154, 659
Sulphburethanes, 386
Sulpho-aceiic acid, 262
fj'uii^acids, 152, 261, 644, 659"
' -benzide, 662

-benzoic acids, 752

-carbamic acid, 386

-carbamide, 394

-carbanile, 614

-catbanjlide, 616

-carbonic acid, 382

-carboxytic acids, 345

-cyanacetic acid, 355

-hydantoihs, 396
Sulphonal, 307
Sulphonazurine, 846
Sulphones, 142
Sulphonic acids, 152
Sulphonic acid, methyl-, 1 53

ethyl-, 153
Stilphoxides, 142
Sulphurea, 394
Sylvestrine, 1003
Sylyic acid, 1008
Synaptase, 508

Tannin, 784
Tannic acids, 784

Tartaric acid, 475
Tartratnic acid, 477
Tartramide, 477
Tartronic acid, 463
Tartronyl urea, 442
Taurine, 319
Tauro-betaine, 319

cholic acid, 1012
Tellurium compounds, 145
Teraconic acid, 431
Teracrylic acid, 241
Terebenthene, 999
Terebic acid, 469
Terephthalic acid, 789
Terpenes, 998

homologues, 1003

nitroso-, 998

nittoso- chlorides of, 998

tetrahydride, looo
Terpenylic acid, 470
Terpine, lOOO

hydrate, 1000
Terpinenes, 1003
Terpinolene, 1003
. Tetraacetylene dicarboxylic acid, 432
Tetradecatyl alcohol, 133
Tetrahydropyridines. 952
Tetramelbylene derivatives, 519

imine, 550
Tetranitromethane, 1 1 3
Tetraoxysuccinic acid, 480
Tetraphenyl ethane, 891

ethylene, 891
Tetrazines, 957
TetraZp" conipounds, 645
Tetrazoiies, 167, 658
Tetrinic acid, 345
Tetrolic acid, 245
Tetrylone, 521

Thaillium diethyl chloride, 182
Thebaine, 992 •
Theine, 449
Theobromic acid, 233
Theobromine, 449
Thiacetic acid, 251
Thialdin; 197
Thiazole compounds, 554
Thienyl. See Thiophene.
Thio-acetals, 306

-acetanilide, 607

-acetic acid, 25 1

-acids, 250

-alcohols, 140

-aldehydes, 193

INDEX.

1039

Thio-amides, 260

-ammeline, 291

-anhydrides, 250

-anilines, 684

-benzaldehyde, 717

•benzoic acid, 743

-carbamic acids, 3861,614

-carbonic acids, 382 v. \

-carbonyl chloride, 376

-cyanacetic acid, 355

-cyanic acids, 277

-cresols, 686

-diphenylamine, 604

-ethers, 140

-formanilides, 260

-glycoUic acid, 355

rhydantolns, 396

-lactic acid, 359

-naphthene, 924

-naphthols, 918
Thionine, 605
Thionuric acid, 442
Thiophene, 521, 529

alcohol, 534

aldehydes and ketones, 534 ^

amido- derivatives, 533

carboxylic acids, 535, 536

condensed derivatives, 537

halogen derivatives, 532

homologues, 531

nitre- derivatives, 532

phenols, 533
. sulpho- acids, 533
Thiopbenin, 533
"Thiophenol, 672
Thiophyllin, 449
Thiophtene, 924
Thiosinamine, 396
Thiotolenic acids, 535

tolene, 531

urea, 394

urethanes, 386
Thioxanthone, 983
Thioxine, 531
Thymene, 688

Thyino-hydroquinone, 694 ~»*
Thynioil, 705
Thymol, 687
Thymo-quinone, 694
Tiglic acid; 241
Tin compounds, 183
Tolane, 886
Tolidines, 845
Tollylene alcohol?, 712

Tolu anthrazine, 986

Tolu balsam, 742

Tolubenzoic acid, 864

Toluene, 572

Toluene derivatives, 583, 584, 585

nitro-derivatives, 590

nitroso-derivatives, 591

sulphonic acids, 665
Tolu-hydroquinone, 694
Toluic acids, 753

aldehyde, 721
Toluidines, 623
Tolunaphthazine, 986 \
Tolunitrile, 734
Toluphenazine, 986 ^ •
Toluquinolines, 969 _^
Toluquinone, 704
Toluquinoxaline, 980 ^
Toluylene, 885 v

blue, 708

diamines, 626"

glycols, 886 .

hydrate, 888-

red, 986, 988-
Tolyl alcohols, 711

phthalide, 864
Trehalose = Mycose.|
Triacetamide, 259
Triacetonamiue, 208 '
Triacetonine, 2S9
Triazole compounds, ^53 '
Triazoles, phenylatedj 935
Tribasic acids (C„Hj„ — fig), 471 "■
Tribenzoyl ipethane, 891
Tricarbaltylic acid, 471
Trichloracetic acid, 221
-^richloracetoacrylic acid, 344
Trichlorhydrin, 455 *
Trichlorlactic acid, 3S9
Trichlorphenomalic acid, 344
Tricyanogen chloride, 267 '
Tridecylic acid, 232
Trjketones, mixed, 731
Trimellitic acid, 797
Trimesic acid, 797
''Trimethyl acetic acid, 229 ^

amine, 164

carbinol, 129
Trimethylene, 83

bromide, 102

derivatives, 516

Trinitroacetonitrile, 286

Trioxyglutaric acid, 485

••Trioxymethylene, 192 ,

i

I040

INDEX.

Triphenyl acetic acid, 615

amine, 604

benzene,,8S2

carbinol, 866

cyanurate, 613

guanidine, 618

methane carboxylic acid, 880

tricyanide,' 734
Trisaccharides, 511
Trithiocarbonic acid, 379
Trithiocyanuric acid, 281

esters of, 281
Tropaeolines, 644, 65 1
Tropeines, 996
Tropic acid, 776
Tropidine, 953
Tropine, 943, 953
Truxillic acids, 813
Tuberculin, 1013
Turpentine oil, 998
Tyrosine, 775

U.

Umbellic acid, 821

Umbelliferon, 8zJ

Undecolic acid, »|.5 t

Undecylenic aci* 231

Undecylic acid, 231

Unsaturated tetracarboxylic acids, 482

Uracyl, 442, 957

Uramidobenzoic acid, 750

Uramil, 441

Urazole, 553

Urea, 18, 386 '

Urea chloride, 376

Ureldes, 391

Urethanes, 382

Uric acid, 445

Uvinic acid, 527

Uvitic acidj 790

Uvitonic acid, 949

V.

^_Valel■aldehydes, 198
vaTeric acids, 228
Valeridine, 198
Valeritrine, 198
Valerolactone, 363
Valeronitrile, zS^"^
Valerylene, 89
Valylene, 90

Vanillin, 725

alcohol, 714
Vanillic acid, 780
Varnishes, 1008
Vaseline, 78
Veratric acid, 779
Veratrine, 998
Veratnbl, 690
Victoria blue, 876

green, 858

orange, 686 •
Vinaconic acid, 517
Vinyl, 97

alcohol, 134
Vinylamine, 163

bromide, 97

chloride, 97
Vinyl ether, 140

ethyl ether, 140

iodide, 97

malonic acid, 428, 517
Violet-aniline, 990

Hofmann's, 873
Violuric acid, 441
Viridin, 869
Vitellin, 1015
Vulpic acid, 892

W.

Wax, 255
Wintergreen Oil, 767

X.

Xanthic acid, 380
Xanthine, 448
Xanthone, 860
Xanthoquinic acid, 973
Xeronic acid, 431
Xylenes, 572, 573 ,
Xylenols, 687
Xylic acids, 757
Xylidic acid, 790
Xylidines, 624
Xyloquinone, 704
Xylose, 483

Zinc ethide, 180
methide, 180