The chemistry of the terpenes

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{E CHEMISTRY OF THE TERPENES

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U, aN, THE CHEMISTRY _

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THE THRPENES

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F. HEUSLER, PxD.,

PRIVATDOCENT OF CHEMISTRY IN THE UNIVERSITY AT BONN.

AUTHORIZED TRANSLATION

BY

FRANCIS J. POND, M.A., Px.D.,

ASSISTANT PROFESSOR IN THE PENNSYLVANIA STATE COLLEGE.

CAREFULLY REVISED, ENLARGED AND CORRECTED.

PHILADELPHIA :
P. BLAKISTON’S SON & CO. v
1012 WALNUT STREET. | oe
1902

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P, Buaxisron's Sox & Co.

Copyright, 1902, by

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Genermrata Proressor OTTO WALLACH
ae THIS VOLUME IS |
GRATEFULLY DEDICATED

BY THE AUTHOR AND TRANSLATOR.

PREFACE TO THE AMERICAN EDITION.

‘Tue favorable reception of the German edition of Dr. Heusler’s
work renders it unnecessary to offer an excuse for presenting this
translation and revision of “The Terpenes.” The chemistry of
the terpenes covers a portion of organic chemistry which has ex-
perienced a very remarkable development in the past few years,
and, since the chapter on the terpenes in most works on organic
chemistry is necessarily very limited, it seemed desirable to have
at least one book in English which should be devoted exclusively
to this subject. It is desired that this translation shall serve
this purpose.

That the German edition has already proved of great value to
chemists especially active in this field is evidenced by the remark
of Doctors Gildemeister and Hoffmann in their book, “The
Volatile Oils”: “The monograph by Heusler on the terpenes
has proved itself well-nigh indispensable for the scientific investi-
gations of terpenes and their derivatives.”

Before presenting this translation, it has been necessary to care-
fully review the very numerous contributions on the terpenes
which have been published since the German edition was issued,
and to introduce the results of these investigations in this edition ;
in doing this, it will be obvious that, although a vast amount of
literature has been condensed into as small a space as possible
and many important compounds are merely mentioned with
references to original papers, the book has been enlarged to a
degree very unusual in a translation. The task has proved a
severe one, but I have endeavored to keep the plan of Dr.
Heusler’s work intact, and have introduced the large amount
of new material in those places which appeared to me the most
desirable. I have not distinguished in any way the separation of
the old and new material, as such a plan did not seem advisable.

vii

Vill PREFACE.

In the translation I have studied to keep as close to the original
as possible, and yet give a clear version. The chapter of intro-
duction is without change from the original edition. The table of
constituents of the ethereal oils, which was added to the German >
work, has been omitted because such a list is no longer of so great
importance since the translation of “The Volatile Oils”? by
Professor Kremers. Following Dr. Heusler’s plan, the many
researches on the derivatives of Japan camphor, such as the in-
vestigations on camphoric acid, etc., have not been introduced.
An index has also been added.

The writer desires to express his obligation to Mr. Jesse B.
Churchill, Instructor of Chemistry at The Pennsylvania State
College, for valuable assistance in the reviewing of literature,

preparation of index and proof-reading.
F. J. Ponp.
Strate CoLuecs, Pa.,
May, 1902.

PREFACE TO THE GERMAN EDITION.

THE following monograph was originally compiled for the
“ Handworterbuch der Chemie.” The article which was written
for this collective work on chemistry was printed some months
after the completion of the manuscript; at this time a review of
the work which had appeared during these months was added, the
effort being made to render this review as complete as possible.
The fact that at the present time the chemistry of the terpenes
occupies a very prominent position in scientific interest led the
author and publishers to publish the article separately in book
form.

The outward form of the “ Handwérterbuch” was of course
retained in the publication of this book. Most of the literature
of the intervening months has been reviewed, and certain inaccu-
racies which appeared in the original article have been corrected.
The publication of this book may be justified by the fact that the
recent advances of the chemistry of the terpenes are, perhaps, not
generally recognized.

I may refer to the chapter of introduction for the principal
points of view from which the compilation of the monograph
has proceeded ; I still regard these principles as correct.

I wish to express my thanks for the valued assistance which
Mr. E. Gildemeister of Leipzig and Mr. J. Bredt of Bonn have
repeatedly extended to me in the course of my work. I am
indebted to my friend, Dr. Gildemeister, not only for the table of
constituents of the ethereal oils, but he has repeatedly placed his
experience at my disposal in reviewing certain parts of the work,
and finally in reviewing the entire book. My honored colleague,
Dr. J. Bredt, has frequently given me valuable suggestions, and

has kindly read one proof.
F, HEUvsLER.

ix

Per EN UML 200 sch ath Od Mauve See Fup fuk a68 9 aay depo deaggarnate 17

SPECIAL PART.
ITERPENES, C5Hg ...........00cc00000s Reo std TRA nd 0s dv sus aca 31
Isoprene, C5Hs ....... CR RD cas dataz bliss tke keddeveist eens Us 31
SR RN MMOMERA Said 35565050 Casas 552200553 6e ces cine sosesedcsavesoaseds 34
Se EE UR SU Foie g yates cise ckcvse} isseseoceperdvcacseens 34
I eo sah Vara tas nce aaessGsde~3< 255 saccpassadtieedarens 56
: NNN Gear CS tse y cb sa vised ves sald dss cetas xc cacerorsbecones 66
EE AEs AMPROMOIIG 6551056. cscssscarecedsescirecsenetevscoensssendenensses 71
mi ET UREEO Ly occ se, cccpactasaatcatc lites uecsedssaocsdecticecesasons 85
EMMNC ORIOL Acts pevevaseterrtsastte diese Us de sess sesictnsceacceteas 99
MN rat eed ies rete ve rte. cece cikasecsnecetecsnstsy. 103
RMU glee sednsunescnaieds sa kanes veskevcsc+vsaneceseees 105
ES SIONS 0 Ry ee a oe 108
AMES Ss ESSE Dotw oleae oe x84 oUbos ens acrene sescevabuesaree 112
nO, Thujene (Tanacetene). ............0ccccceccscsssccscecsvesencees 118
11. Terpene from the Resin of Indian Hemp................. 119
ere, yMtmetical Terpeme.... . iv. ......scceciscccscscsssscsessccesses 120
RI OMUMOUGHOS, fisccacdsccsscscdvessensccscavecesecvordsccecyacdescsce 120
TRIMMER MOG Sci cocccedigadescssse¢scekvens cies o0c0ncQs Reogsevseo renee 120
15. Tricyclene ..............00060 Pe A Her ee CE ee 121
EN ECON s dae swt cn cy corse veson ofc vpobeeecseseacteeseds 121
RMR MEOTID ies ih osGsdenclesocsesecstsecs eens ee Lg te Seno 121
RBONS, CjoHjg........ SS, oe Se Ro hat ha ee 123
i . Dihydrocamphene....................44. Sah Mw cheap. sivas seeseces 123
Be) 2, Teodiliydrocamphenc ...........2...s<s..¢e0secseccsesseesesesers 124
UM MORPUOINGHEDONO <./.+.<..0-0ccs:ss0s00sss+aeSarsco, coosensoteseeeis 124
INE RIGHG evi ckULt, vans neeeeciselevsne Sache sdenass<denssrs 126
MMIII Cig Pag ss scsdacce.veecindese ets seestacccestses PIR aAGR oy ... 180
IZED COMPOUNDS RELATED TO THE TERPENES, CjoHig ......... 138

___I. SuBsTANCES WHICH CAN NoT BE REGARDED AS DERIVA-

_—“‘is TIVES «OF . THE HYDROCYMENES. (ANALOGUES OF

Bese me PINENE, CAMPHENE, FENCHENE ).........ccceeeeeeeesceenes 133
xi

xii

TABLE OF CONTENTS,

PaGE
1. Camphor, C19H16O.....:.20+:ss0sessesescnssesessnencsseusaeaneane 133 —
2. Borneol, CioH17OH.........0.s0ccesscess saeccayeensensnaewansenee 141
8. Isoborneol, CioH170H. .......-0s.0cssscdecnosesherschuslenieeae 146
4, Camphene Glycol, CyoHi6(OH)2............+.sserererereeene 151
5. Camphol Alcohol, CjpH1gOH.... ....:.scceseseceseeseeseeeee 152
6. Camphenone,, Cy9H14O....00:.+...scnessecetevecatenseesn mannan 152
7. Pinocamphone, C19H1¢0........s0s0esecensesbesraesnnesenmneee 154
8. Pinocampheol, ©;9H17OH......0....:..5;ssessnessuasaseeeeane 155
9. Fenchone, Cy9H1¢0............+000ss-cwaessaesdeapeeanersnneennan 155
10. Fenchyl Alcohol, C1oHj7OH.............csscceccsvseusseeenens 170
11. Isofenchyl Alcohol, C3o9H17OH................0cseeecesseeeees 174
12. Fencholenyl Alcohol and Isofencholenyl Alcohol,
C19H17OF 3 .0n.5.050s0case0es 40090350 0ade bans oe 176
18. Fenchenole, CjpH1gO..............02+0ss¢s0n0sbsh Menno eeeeEe 177

II. Compounps WuHiIcH MAy BE REGARDED AS DERIVATIVES

OF THE HYDROCYMENES.......s..:..devsnueaysueraeeyyeeeen 178
A. Substances Containing two Ethylene Linkages. Ketones,

CyoH140, and Alcohols, CjpH150H............0sceeeeeeeeeees 178
1, Carvone, CipH14O.........0c0s:0, cvessusseuenchs dante 178
2. Carveol Methyl Ether, C1pH15OCH3..............20c000eeee 197 .
8. Eucarvone, C19H140........:0.:c..casneseneseeaueueeenennan 198
4. Pinocarvone, C19H14O..........++ sasosseesssuvnssuebaeeea 201
5. Pinocarveol, CioHi5OH...........+.+<00ss0ssedss use ueeap nea 202
6. Pinenol, Ci9Hi5;0H oc cccccceensccceceeeabebcceslosbasceceeses sess 202
7. Pinenone, CyoHigO........<ssiceeescecdevusdenees eee aes 203
8. Limonenol, CioHysOH........::5s000000ssacspebewep eee 2038
9. Limonenone, C19H 140... ....:..5.+s2s»s0secesbseaulede Pom 204
10. Sabinol, C19Hi;0H perc cececennccecescesseeses besbeseseesecneces 204

B. Substances Containing one Ethylene Linkage. Ketones,

CioH160, Alcohols, C1o9Hi7OH, and Oxides, CipHig0... 206

1, Dihydroearvone, CypHi¢0....:...5...0asaeeanuaeeneness een 206
2. Dihydrocarveol, CigH17OH.............0:scsesecececececeseres 212
8. Carvenone, Cig HO. ©. ie. dvsss0ssedcoteceneceeeeeeeeeeenaae 216
4, Carone, CypHigO s....ccsc0sccs onavetel ouccteconteesea nee 219
5. Dihydroeucarvone, CypH gO ..........000essescevessevcescenoee 223
6. Dihydroeucarveol, CyoH17OH...........ccceeceecessseeeesenees 224
7. Thujone (Tanacetone), CyoH1gO..........cccceeeccseeeesessees 224
8. Thujyl Alcohol (Tanacetyl anes C1oHy7OH......... 234
9. Isothujone, CjoH3,0... sacha yadyaidce s¥slcbonterernetere eee Ena
10. Carvotanacetone, C1oH60.. dared nacbcaikegs SEU pRaeEES Seo el 236
11. Pulegone, CioH190... Be sie Ok
12

. Isopulegol, CoH; -OH, aad ‘tegpelagine: CioH190.. woes 247

13.
14.
15.
16.
17.
18.

19.
20.
21.

TABLE OF CONTENTS. xili

PAGE.
PROTONS, Cigks sins f. cio endpcnapccccissieccesdoceceasoocns 250
UE MITREUOT CAGIRIAO? so sccg'de sp eee>tsisrnpcapassanaegecvoecesecks 251
Pinolone, Cy)Hig0, and Pinolol, CipH370H ............. 2538
A®’-Menthene-2-one, CjpHgO...........000.ccesesccececcececses 253
TONNE RIERA NUN 5555 ch bas dup Vanes has on 40ddrebadareciaeds 254
Isomeric Terpineol (4*®-Terpen-1-ol), melting at 69°
Md er oO ROPER ado Liga eh Snide iv hess bacss idie> sasd «odes. 269
Isomeric Terpineol, C19H17;0H, melting at 32° to 33°. 273
RSME COMAREAMO DS Toke oc hicnsg feild UF vtphidng i0049 0<Ktuc ces aby seve 274
PMN Le Cig a, 2052 ig aindicn tp Sis ptaveweessar sess -eseeceen 285

C. Substances Without an Ethylene Linkage. Ketones, CioHis0,

Alcohols, Ci9H1g0H and Cy9His(OH)o, Oxides, Ci9Hi,0,

RES IE EST OF Siretor Cg pate aE til a a 287

1, Tetrahydrocarvone (Carvomenthone), Cj9Hj,0.......... 287
2. Tetrahydrocarveol (Carvomenthol), CipHigOH.......... 291
3. Tetrahydroeucarvone, CyoH1gO...........ceseeeeceeeeeeeeeees 298
4, Thujamenthone, CipHigO.............-s0sescsececeecsceescssees 294
5. Thujamenthol, Ci9pH19OH.................ceceessseareaceccssecs 295
apie EINEM RIDES ISO so fcaauspustessereecescecsbacsessdesesenpises 295
ee OMNBENIRS MR IGRE TORI EN oda oc int cofeceessqescecscesee. seeveceee seve 308
8. Tertiary Carvomenthol, CipH19OH..................00c0000: 316
9. Tertiary Menthol, CipHj9OH ................0.sceeecccsessees 317
Beis a ERI, COIR EE AOE A. oo csisin a s25.occcinscs accuses cbdcbcedeceses 318
11. Menthene Glycol, CjopHig(OH)2........... 0... cececeeeeeeeeeee 823
Ms PRAMIOGIO,- Deg hl 190 nis s.en. css ctaccs cdvcccscossccceascccscesdeceses 323
13. Terpan-1, 4, 8-triol, C19pH17(OH)3.................cedeeee eens 334
14, Trioxyhexahydrocymene, C19H17(OH)3..................45 834
15. Pinole Hydrate, Cy9H170°(OH) ........... ccc cece ee ee ee ee ee 334
BG Pamonetrol, Cighlig(OH)4.......5.....6...ccccccscccsessceseens’ 8384
17. Pinole Glycols, ETRMUMN DMEM Taye) occ 5 dona fecdordeve tn s ictus 334
AMIDO-DERIVATIVES OF THE TERPENEG.............0.0cececeeeececeeeeees 836

I. BASES WHICH CAN NOT BE REGARDED AS DERIVATIVES

OF THE HYDROCYMENES. (ANALOGUES OF PINENE,
CAMPHENE, FENCHENE, AND OF CAMPHOLENIC ACID

UMN ae et MTRROVEIOSEEE! FLOTD))o 76025. s00 oer veravsccccepessceseonss 336
Per AMY IAIMIDS, CQ HLIGIN 299... 0s sececcccccceeescvssceases iseessvenes 336
2. Amidoterebentene, CyoHisNHo.............00cccceeeeeeeeeeees 338
Be OTM y AMIN GS) Cig E77 IN ELD. 26.0500 55 ccc tscesc scone ssseeccoess 340
4, Camphylamines, CoHisCHoNHo..............0.ececeeeseeeees 846
5. Fenchylamine, CjoHi7z7NHo...............cccecceesscsceeeewens 347
6. Fencholenamine, CgHi5CHoN Ho............... ccc eeeee scenes 351
7. Campholamine, CgHi7CHoN Ho................cceeeeee eee eees 353

xiv TABLE OF CONTENTS.

PAGE.
Il. BASES WHICH MAY BE REGARDED AS DERIVATIVES OF
THE HYDROOYMENES:, «i. cisccucccocecvcevecesbarseaenonenanees 3854
A, Amines, CioHisNH2, Containing two Ethylene Linkages..... 354
1. Carvylamines, CioHi5NH2...... WE iy fo 854
B. Amines, C1yHi7NHe, Containing one Ethylene Linkage...... 356
1. Dihydrocarvylamine, Cj9H17NHo............0scseeeeceeeeenes 856
2. Carylamine, C19H17N Ho.........000<05ssehennsueestnas tas eeeeaen 358
8. Vestrylamine, CipHi7zN Ho.........:.s-0ceseoosecatevesseaneeiam 359
4, Dihydroeucarvylamine, CyoHi7NHo..............0sc0eeeeeee 359
5. Thujylamine (Tanacetylamine), CjoHi7NHo.............. 360
6. Isothujylamine, CjopHiz7NHo.............csecscccessscsevenssens 362
7. Pulegylamine, CipHi;N Ho... ......:.c.cessssaseesnsevessetpaeee 362
C. Amines, CioHigNHe, Without an Ethylene Linkage........... 364
1. Carvomenthylamine (Tetrahydrocarvylamine), Ci9Hio-
INH «on. ccdcccccnceesccuscesceescdensye cule tng tnmamnE eihiaxa tes 864
2.. Menthylamine, CypHigN Ho. ...:..% 0.150. c.ceeseseeneaeeanene 365
3. Tertiary Carvomenthylamine, CjpHigNHp................ 373
4, Tertiary Menthylamine, CjpHigN Ho...............0ceeeeees 374
AMIDO-DERIVATIVES OF PHELLANDRENE..........csceesscceceecerensssses 374
1. Amidophellandrene, CjoHi5NHo...............00068 deasaseen 874
2. Diamidophellandrene, CioHig(NHo)o..........eeseeeeeeeeeee OTD
OLEFINIC MEMBERS OF THE TERPENE SERIES..........ccececcececereers 377
A. Hydrocarbons..........+2000+ss0cesse00eseeeeyndneeey thsale penne 377
1. Myreene, C1pH ig ........2.5:0190css0s cneon cenenep elena anna 377
2. Anhydrogeraniol, CipH1¢..........<0.00ssssnscavensussepeanenae 379
8. Olefinic Terpenes in Oil of Hop and Oil of Origanum. 380
4, Linalolene, CoH 1g.....:.000.0+s0s0+00eessawsuaennilneee een 380
5. Hydrocarbon,'CioHig, obtained from Menthonylamine, 380
B. Oxygenated Compounds............sscccssrsevcsssessncnnssbevegaeasess 381
(G): AlCoROL 8... 5 50.5.00sniens osssveponse out snedate eae santos tesa Meee hae 381
e 1. Linalool, Cj9Hy7OH. ... .....5.65.050 00 n0sdeeneeen een teeta 381
2. Geraniol, Ci9H17OH ...........05.0ccnnacbheesnsueenasteaienenaninne 887
8. Menthocitronellol, CjpHigOH............... ines oe 393
4. Citronellol, CigH19OF .......0.<cavecedonscentuateeennteeaeenene 394
(b) Aldehydes .........6...000seenpsstgasdsehenhsse tentgnw eyes eae 396
1. Geranial (Citral), CioHigO.:..::,.<<..sscsaseseeeasgieeeteenenee 396
2. Menthocitronellal, CypHigO...........scececeesccecccesseeevcese 409
8. Citronella], CioH gO. .020...0.i5s5.uceesceepegees sesbeceeemaen eee - 409
Cy, AMEN ER. 065560 vnssniiv nde cesveayooushewoungandet a dtack teal eee aaa 413
1. Menthonylamine, CjoHjgNHo.............ceecseeceesseveeees 4138
SESQUITERPENES AND POLYTERPENES..........sscsecesscesccsecsecccesces 414

TABLE OF CONTENTS. XV

PAGE
Oe NCTA Oy BARRY Re ee eee 414
RRCMEOONNY IDO, C1GIS Of. ono cd es cee ssedesicesscccenesssse saccedes 417
MN Pay OUTER ONS nce chaps ieee cevavessannvucsepenwes couaecansevnys 421
MRE MIRUREOTEG@:s AC HIRER OAs cacy ascnns sows cdisesanseesdicnssacesopedhoes ony 421

5. Cedrene, Cj5H, and Cedrol (‘‘Cedar Camphor’’ ),
SrA MRO EN er soccer cece ceccee tates Lika roe vcenss slevadeteeeasiivers 423
GCaneb Camphor, Opp MocO Rois cei svna. ccctsecssepecessnecs 424.
7. Ledum Camphor, Ci;H2;OH, and Ledene, CisH...... 425

8. Patchouly Alcohol, Cj;H2,0H, and Patchoulene,
PGE iig wean rek ee eae TPHIETk Seder eh ian eus Teo aisegeided beakes 425
PR CTI TUND SE acer aa Sank ce yesiesineweess as csvectedecevayadase 426
10. Santalol, C1;H2;0H, and Santalene, C5H094............... 426
11. Galipol, Ci;5H250H, and Galipene, Cj5H0o4................. 428
12. Caparrapiol, C1;H2;0H, and Caparrapene, C15H94...... 428
eran POMIN AE ETM, anc chs elsenesincseses casas cieresdcasevesdscess 429

14. Olefinic sesquiterpene, Ci5H24, from the oil of citro-
Oo) NR ORES PES AE ee 430
MN Ee eU cr ecdls sty st48depee er cibsine cess seks cusceddescvevcssrsts 431
RDS HAEDER, ack g sty vats cerned ves tsaeseresshyassisvasessesceseasevses 432
1. a- and B-Amyrin, Cg9H4gOH...............ccceceseseeesceeeees 432
NRO EEGs c Ca iain ocd ove kccewedanatasbasaesiscsdvors sasssacnees 435

THE THERPENKS.

THosE hydrocarbons which have the empirical constitution,

C,H,, are termed terpenes. Four main classes are recognized :

Hemiterpenes, C,H,,
Terpenes proper, Coy
Sesquiterpenes, C,,H,,,
Polyterpenes, (C,H,),.

The terpenes proper and the sesquiterpenes form the most im-
portant constituents of the ethereal oils. In the latter, several
terpenes often occur together, and further, the ethereal oils fre-
quently contain oxidized compounds which in many cases are not
separable from the terpenes by fractional distillation, or only im-
perfectly so.

The result of these conditions was, that during the period be-
fore it was known how to sharply characterize the separate ter-
penes by chemical reactions, and to determine them as individuals,
mixtures of this character were often regarded as chemical in-
dividuals, and were accordingly given independent names.

To Professor O. Wallach belongs the distinction of having
elevated the methods of the terpene chemistry, by a series of
superior experimental investigations, to such a plane, that the
recognition and separation of the several terpene hydrocarbons
have become relatively simple matters for the chemist.

These methods gave the first possibility of an actual working
system to these substances, and moreover permitted the accurate
establishment for the first time of the numerous transformations,
which, under the influence of the greatest variety of reagents,
take place so easily in this group of hydrocarbons.

It has already been mentioned that many oxidation products
are present with the terpenes in the ethereal oils. It is evident
that these compounds, occurring together in the plants, are very
closely related to each other. What these relations are is ren-
dered entirely clear by the study of the terpenes. Not only have
many terpenes been artificially prepared from such natural oxi-
dized compounds, but also a complete series of oxidation products
have been successfully secured from natural terpenes, and these

2 17

18 THE TERPENES.

substances are isomeric with, or closely related to, the natural
oxygen-containing members of the terpene group.

The so-called camphors, a name long used to designate these
oxidized compounds, have been brought into so close a relation to
the terpenes that a separate consideration of these two classes of
compounds is no longer justifiable. In fact, it is impossible to
develop the chemistry of the terpenes unless these oxygen-con-
taining compounds are considered as members of the terpene series.

With this point in view the following monograph has been com-
piled, and only the one reason of outward conformity has pre-
vented the carrying out of this fundamental idea to the end.

Japan camphor, while very closely allied to the terpenes, has,
however, such an extremely large number of derivatives that an
exhaustive description of them would demand as large a space as
the derivatives of all the remaining members of the terpene group
taken together. Hence the only derivatives of this compound to
be mentioned will be those which stand in an especially close re-
lation to other members of the terpene group.

While the discussion of camphor and its derivatives will be
limited, an equally exhaustive treatment for the remaining oxy-
gen- and nitrogen-containing compounds of the, terpene group will
be sought, as for the terpenes themselves.

The terpenes proper may be divided into two groups. The
hydrocarbons of the first group contain one; those of the other
group contain two ethylene linkages. As a class, the terpenes of
the latter group may apparently be regarded as true dihydrocy-
menes. The known tetrahydrocymenes and hexahydrocymene,
which are closely related to these terpenes, are discussed in the
following treatise.

Corresponding to hexahydrocymene, which does not occur nat-
urally, are oxygen-containing compounds which are widely dis-
tributed in nature, namely, menthone, C,,H,,O, and the alcohol
corresponding to this ketone, menthol, C,,H,OH. Two com-
pounds, carvomenthone, C,,H,,O, and carvomenthol (tetrahydro-
carveol), C,,H,,OH, structural isomerides of the above-mentioned
substances, are to be considered as the completely hydrated parent-
substances of an extremely large number of unsaturated, oxyge-
nated members of the terpene group. Nevertheless, they do not
themselves occur in nature. :

If one molecule of water be eliminated from menthol or earvo-
menthol, hydrocarbons, C,,H,,, are formed, which can be consid-
ered as structural isomerides of tetrahydrocymene. The following
formulas illustrate the constitution of these compounds. (For the
nomenclature, see page 23.)

INTRODUCTION.

H;
H

19

H, H,

H; H, H, Pus
ke nd JH a, SH
Bebo. : Hee
H, H,C CH; H, H,
Hexahydrocymene
H (Terpane, Menthane). H
H H
H,C CH; H, CH;
Menthone Carvomenthone
(8-Ketohexahydrocymene, (a-Ketohexahydrocymene,

Terpan-3-one, Menthan-3-one).

Terpan-2-one, Menthan-2-one).

HE H
H, H, H, ee
H, HOH H, H,
H
sf A
%

H,C CH, H,C CH,
Menthol Carvomenthol
(8-Oxyhexahydrocymene, (a-Oxyhexahydrocymene,
Terpan-3-ol, Menthan-3-ol). Terpan-2-ol, Menthan-2-ol).

‘H ul
H, H, H, H
H, Hd H,
Yin
1H.
H,;C CH; H,C CH;
Menthene Carvomenthene
(A?-Tetrahydrocymene, (A!-Tetrahydrocymene,

A*-Terpene, A’-Menthene).

A!-Terpene, 4!-Menthene).

Other compounds, isomeric with menthol and carvomenthol, are
known, which possess the character of tertiary alcohols, and, ac-
cording to Baeyer, have the following constitution :

20 THE TERPENES.

A; oH
H H

H, x H, H; ae

is fe mt pm,
H H

f

H
é CH; H,¢ ‘va,
Tertiary Menthol. Tertiary Carvomenthol.

Theory also clearly allows other isomeric tetrahydrocymenes to
be predicted, although they are still unknown.

By consideration of the above-mentioned derivatives of hexa-
hydrocymene, it had to be accepted as a fact, according to the
views prevailing at that time, that a third ketohexahydrocymene,
isomeric with menthone and carvomenthone, could not exist.

The fact more recently established by Wallach that such an
isomeric ketone, thujamenthone, and its corresponding alcohol do
exist, deserves therefore to be emphasized at this point as a matter
of especially great theoretical importance.

If we suppose one methylene group in the hydrocarbons, ©,,H,,,
to be replaced by a carbonyl group, we arrive at the ketones,
C,,H,,O, which contain one double linkage, and are to be regarded
as derivatives of tetrahydrocymene. By reduction of these ke-
tones, C,,H,,O, secondary alcohols, C,,H,,OH, are formed which
may be transformed into terpenes, C,,H,,, by the elimination of
one molecule of water. The reverse process, by which the alco-
hols may to some extent be prepared from the terpenes, C,,H,,,
by the addition of the elements of water, is also possible.

Ketones, C,,H,,O, of this character, which may be considered
as ketotetrahydrocymenes, and their corresponding secondary
alcohols (oxytetrahydrocymenes), have recently been discovered in
exceedingly large numbers. The constitution of these compounds
has not yet been determined with such a degree of accuracy that
an extended discussion of the various views held in regard to the
constitution of the separate members of this class would be of
value here. Nevertheless, we recognize certain of these sub-
stances which must be regarded as derivatives of menthone, and
certain others which are to be considered as derivatives of carvo-
menthone. The following compounds are derived from men-
thone: pulegone, and also in all probability the ketone, menthe-

none, which is formed by heating nitrosomenthene with hydro-
chloric acid.

INTRODUCTION. 21

From carvomenthone are derived: dihydrocarvone and di-
hydrocarveol ; carvenone; dihydroeucarvone and dihydroeu-
carveol; thujone (tanacetone) and thujyl alcohol; and carvotan- |
acetone.

According to Wallach, isothujone appears to correspond to
neither menthone nor carvomenthone. By reduction it yields the
above-mentioned thujamenthone.

_ Aside from the secondary alcohols, C,,H,,OH, just referred to,

tertiary alcohols, C,,H,,OH, are known, which are also to be con-
sidered as oxytetrahydrocymenes. ‘The constitution of one of
these tertiary alcohols, terpineol (melting point 35°), was de-
termined by Wallach and Baeyer independently of each other,
but with perfect agreement in result, and until quite recently
terpineol was represented by their formula :

Later experiments by Wallach, on the one hand, and Tiemann,
Semmler, and Schmidt on the other, however, entitle the formula

1H,
H, i
H, 2
H
H

H,C OH,

to an equal consideration, and, indeed, it appears in all probability

to be the correct representation of the constitution of terpineol.
A large number of bases, C,,H,,NH,, which have been prepared

by various methods from the ketones, C,,H,,O, or the alcohols,

C,,H,,OH, are to be considered with the latter.

_ Ifa molecule of water is withdrawn from the alcohols, C,,H,,OH,

or ammonia from the bases, C,,H,,NH,, a class of terpenes, C,,H,,, _

22 THE TERPENES.

is derived, which contain two ethylene linkages, and are to be
regarded as dihydrocymenes. To this group of terpenes belong :

Limonene (Dipentene), Carvestrene,
Sylvestrene, Terpinolene.

In regard to another terpene, thujene, which belongs here, only
a few statements have hitherto been submitted.

Regarding the constitution of these hydrocarbons, it is worthy
of note that Baeyer believes the constitution of terpinolene, which
results by the elimination of water from the above-mentioned
terpineol (melting point 35°), to be proved with a degree of ac-
curacy equal to that of any other organic compound. .

Hy,

re Na

H,C ve"
|

HC aa

Terpinolene.

It will be judicious, however, to use this formula cautiously for
the present, since Baeyer’s proofs rest to some extent on con-
clusions drawn from analogy, and their strength must at all events —
be supported by the presentation of an extended series of observa-
tions.

Various views have been held from time to time with respect
to the position of the double linkage in the other terpenes of the
limonene group ; but it would be of little interest at this time to
discuss the proposed formulas, since the investigations regarding
these have not yet reached definite conclusions.

If it be imagined that one of the methylene groups in the ter-
penes of the limonene series is oxidized to a carbonyl group,
ketones, C,,H,,O, are derived, which contain two ethylene linkages,
and are to be considered as ketodihydrocymenes. Again theory
allows two classes of these ketones to be predicted, of which one
corresponds to menthone, the other to carvomenthone. Both
classes may be transformed into these two saturated ketones by
hydration. With the ketones, C,,H,,O, which are derived from
menthone, we are as yet unacquainted. The known ketones,

C,,H,,0,

INTRODUCTION. 23

Carvone,
Eucarvone,
Pinocarvone,

are all derivatives of carvomenthone, and this substance
owes its name to precisely this relation which it bears to
earvone. An alcohol, C,,H,,OH, corresponding to carvone, is
known only in its methyl ether, but, on the other hand, an
alcohol, C,,H,,OH, pinocarveol, exists corresponding to pino-
carvone.

These theoretical considerations render it apparent that all the
hydro-derivatives of cymene can be transformed into each other
by thé greatest variety of methods.

The nomenclature of the above-mentioned group of hydro-
cymene derivatives is rendered difficult, if it be desired to
rationally express the structure of a compound in its relation to
hexahydrocymene as the parent-substance. Baeyer' has there-
fore advanced the proposition to designate hexahydrocymene as
terpane ; the tetrahydrocymenes, according to the Geneva com-
mission, as terpenes ; and the hydrocarbons, C,,H,,, hitherto known
as terpenes, as terpadiénes.

The position of the double linkage is indicated by the same
method as that introduced by Baeyer in the case of the hydro-
phthalic acids ; thus, as an example, the above-mentioned struc-
tural formula of terpinolene would be designated as follows :

se
i
=f 20H
A, Ra 3CH,
C
|
8
H,C9 10CH,

A-1, 4(8)-Terpadiéne.

According to Baeyer, the ketones, C,,H,,O, are termed ter-
panones, the alcohols, C,,H,,OH, terpanols, with an index figure to
designate the carbon atom to which the oxygen is attached. The
ketones, C,,H,,O, and the alcohols, C,,H,,OH, Baeyer designates
as terpenones and terpenols.

1Baeyer, Ber., 27, 436.

24 THE TERPENES.

This system of nomenclature, introduced by Baeyer, has the
one disadvantage of giving the old familiar name terpene to the
hydrocarbons, C,,H,,. In order to avoid this difficulty, but, at
the same time, to preserve the unquestionable advantage of Baeyer’s
system of nomenclature, Wagner * has suggested that hexahydro-
cymene be called menthane. The hydrocarbons, C,,H,,, retain the
name menthene, which has already been employed for one member
of this group, while the dihydrocymenes, C,,H,,, may be called
menthadiénes, or terpenes as hitherto.

In the meantime no agreement has been reached as to whether
Baeyer’s or Wagner’s nomenclature shall be introduced.

For the sake of completeness it might be noticed at this
point, that in accordance with a proposition by Wallach,* men-
thone is often designated as f-, carvomenthone as a-keto-
hexahydrocymene, and, correspondingly, all unsaturated ke-
tones which yield menthone by hydration are termed f-, but
all ketones which form carvomenthone by hydration, a-keto-
derivatives.

It has already been mentioned that in addition to the terpenes of
the limonene series, other terpenes are known which contain only
one ethylene linkage, and can not be regarded as simple hydra-
tion products of cymene. Especially is this the case in a family
of closely related terpenes consisting of :

Pinene,
Camphene,
Fenchene.

To these terpenes correspond also saturated hydrocarbons,
C,,H,,. If it be imagined, in a manner similar to that above, that
one methylene group in these hydrocarbons, C,,H,,, be replaced
by a carbonyl group, the ‘ketones, C,,H,,O, are derived, which
are saturated compounds. These ketones, camphor and fenchone,
sustain the same relation to the three terpenes of this class, as the
above-mentioned ketotetrahydrocymenes to the terpenes of the
limonene series. |

The saturated nature of camphor has caused this compound to
be regarded as a ketotetrahydrocymene containing a so-called
para-linkage (Kannonikow,’ Bredt *) :-— es

1Wagner, Ber., 27, 1636.

2Wallach, Ann, Chem., 277, 105.

3Kannonikow, Journ. Russ. Phys. Chem. Soe., 1, 434.
4Bredt, Ann. Chem., 226, 261.

INTRODUCTION. 25

ig
H, a
H,¢ |.

: |
H,C CH,

a According to this, Wallach’ has gradually brought the follow-
ing constitutional formula of pinene into consideration :—

H;' CH,

< Daring the course of further investigations, however, these for-
as have proved untenable, and Bredt?” has proposed the fol-
wing formulas for camphor, pinene and camphene :—

CH, —=CH, CH, ni-=-CH,
[= H, H,C—C—CH,
'H, A, HOH
HH,
Borneol.
CH, CH
| H,C—C—CH, |
2 H,
8 Hy;
_Camphene. Pinene.

“Bredt’s ‘camphor formula interprets the sasaki of this com-
pounc especially well in the formation of paeixisacsine acid

1Wallach, Ber., 24, 1545.
seat, Ber., 26, 3047.

26 THE TERPENES.

from camphoronic acid resulting from the oxidation of camphor.
The behavior of pinene can be explained with the help of the
above formula, if we assume with Bredt that, by the action of
certain reagents, especially aqueous acids, the formation of an
atomic group C(CH,), may result, by which an isopropyl group
is formed, accompanied by a break in the pentamethylene ring.
Thus the formation of a hexahydrocymene derivative is made
possible. For example, Bredt explains the formation of terpine —
in the following manner :

CH, OH;
CH,—0===CH a
H,C CH, +2H,0= H, Ra
CH, | an H,0—(O1)—CH,
H, on,
Pinene. Terpine.

Whether this formula proposed by Bredt will be proved cor-
rect in all points, time alone will tell. Some investigators have
already proposed modifications of Bredt’s formulas, which seem
to better suit certain facts.' As a rule, in the present state of our
knowledge, criticisms arise against all such formulas. It would,
therefore, be too early at this time to pass a critical judgment con-
cerning the value of the extremely large number of formulas pro-
posed for pinene.

Fenchone, which very closely resembles camphor, stands in its
relation to the latter, as a meta- to a para-compound (Wallach).
Fenchene undoubtedly possesses a similar relation to cam-
phene.

Aside from the terpenes, C,,H,,, already mentioned, two others
are known, terpinene and phellandrene, both of which appear to
possess but one ethylene linkage. They do not, however, admit
of classification in the same group with pinene, camphene and
fenchene. Both are without doubt closely allied to cymene.

The relations of the terpenes, C,,H,,, to the numerous ketones
occurring in nature or artificially prepared, and to the monobasic
alcohols have now been presented. There remains for conclusion
the consideration of a series of polyvalent alcohols known in the
terpene series. Several of these alcohols lose water with great
readiness, forming anhydrides which possess the character of ox-
ides. To these anhydrides belong the saturated cineole, C,,H,,O,
pinole hydrate, C,,H,,O-OH, and fenchenole, C,,H,,0.

‘Wagner, Ber., 27, 2270; Tiemann and Semmler, Ber., 28, 1345.

INTRODUCTION. 27

After it was recognized that certain terpenes were to be
considered as dihydrocymenes, the next step was to synthe-
size the latter hydrocarbons, and to identify them with known
terpenes. The long familiar reaction by which a terpene,
C,,H,,, results from heating isoprene to a high temperature,
and which Wallach has characterized as dipentene, can be
looked upon as the first synthesis of a terpene; the course of
the reaction was not, however, clear, and the constitution of
isoprene, which had not been prepared by synthetical methods,
was not known.

After Wallach? in the year 1890 had demonstrated that cer-
tain unsaturated aliphatic ketones (methyl hexylene ketone,

C,H,,O, and methyl heptylene ketone, C,H,,O), could easily be

converted, by the elimination of water, into lower homologues of
the terpenes (dihydro-meta-xylene, C,H,,, and dihydro-pseudo-
cumene, C,H,,), Bertram and Walbaum®* in 1892 succeeded in
accomplishing the partial synthesis of two terpenes, dipentene
and terpinene, by the elimination of water from an unsaturated
alcohol of the fatty series, linalool, C,,H,,OH, which is found in
nature.

The complete synthesis of a dihydrocymene, C,,H,,, was accom-
plished in the year 1893 by Baeyer,* who distilled the dibromide
of methylisopropyl-succino-succinic ester with quinoline. The
resultant dihydrocymene, boiling at 174°, has not yet, however,
been identified with any known terpene.

In this connection it might further be recalled that a ketotetra-
hydrocymene, C,,H,,O, has been synthetically prepared by Knoe-
venagel.” This compound, to which Knoevenagel ascribes the

formula
CH
O eu :
ma) ‘H,
Nir

CH

is derived from isobutylidene diaceto-acetic ester,

Wallach, Ann. Chem., 227, 295 and 302.

*Wallach, Ann. Chem., 258, 338; 272, 120; Ber., 24, 1573.
SBertram and Walbaum, Journ. pr. Chem., N. F., 45, 601.
4Baeyer, Ber., 26, 233.

5Knoevenagel, Ber., 26, 1085; Ann. Chem., 28/, 44.

98 THE TERPENES.

cooc,H;
CH<COCH,

(CH,),CH—CX eee
CH<¢000,H,

Although all the above-mentioned terpenes, C,,H,,, as well as
their related oxidized compounds, possess a ring formation of the
carbon atoms, nevertheless, another series of hydrocarbons, C,,H,,,
and several oxygen-containing compounds, C,,H,,O, C,,H,,O, and
C,,H,,0, are known, which belong to the aliphatic series. These
compounds also form important constituents of very many ethereal
oils ; and, since they possess a close connection to the terpenes
and camphors with a ring formation of carbon atoms, these hydro-
carbons, C,,H,,, are designated as olefinic terpenes, according to a
proposition of Semmler,’ while the oxidized compounds are classed
under the group name, olefinic camphors.

Our knowledge in regard to the olefinic terpenes is still very
meager, but it should be mentioned that such terpenes result, not
only by the elimination of water from olefinic terpene alcohols,
C,,H,,OH, but exist as well already formed in nature. It should
further be mentioned that hydrocarbons, C,,H,,, are known, which
belong to the aliphatic series, and correspond to menthene.

The olefinic camphors are better known. They are widely dis-
tributed, and, in consequence of their agreeable odor form, to some
extent, very valuable constituents of numerous ethereal oils. ‘Two
primary alcohols, C,,H,,OH, are known, the optically active lin-
alool, and the optically inactive geraniol, the latter standing per-
haps in the same relation to linalool, as dipentene to the active
limonene. Both alcohols yield, by oxidation, the same aldehyde,
geranial (citral), C,,H,,O, which also occurs in nature. Accord-
ing to Tiemann and Semmler, geranial is probably a dimethyl-2-6
octdién-2-6-al-8 :

CH; —(=CH—CH,—CH,—(=CH—CHO

3

Citronellal, C,,H,,O, is a second aldehyde, which belongs to this
class and which likewise occurs in many ethereal oils.

The close relations of these substances to the ordinary terpenes
are first suggested by the circumstance that geranial, by the
elimination of water, is quantitatively converted into cymene
(Semmler’). According to Tiemann and Semmler, this reaction is
preceded by a transposition of the double linkage :

1Semmler, Ber., 24, 682.
2Semmler, Ber., 23, 2965; 24, 201.

INTRODUCTION. 29

A Hy
H te H H
H er) == ! H
H, }
A H
H;C CH; H;,C CH;
Geranial. Cymene.

More important, however, is the fact that, according to Bertram
and Walbaum,’ two well known terpenes, dipentene and terpinene,
may be obtained by the removal of water from linalool or geraniol,
C,,H,,OH. In a similar manner, Tiemann and Semmler? have
succeeded in the transformation of an extended series of linalool
and geraniol derivatives into isomeric cyclic compounds by treat-
ment with sulphuric acid.

While the naturally occurring olefinic terpenes and camphors
can thus be easily converted into ring compounds which are in
part identical with those occurring in nature, the investigations of
Wallach* have shown that, conversely, cyclic compounds may be
transformed into substances which occur in nature, and which
must be designated as olefinic camphors. Thus, according to Wal-
lach, menthonoxime, C,,H,,NOH, yields menthonitrile, C,H,,CN,
by the elimination of water. Although menthonoxime is a satu-
rated cyclic compound, menthonitrile possesses the character of an
unsaturated aliphatic substance. By reduction, menthonitrile is
easily converted into menthonylamine, C,,H,,NH,. This base,
which is isomeric with the cyclic compound menthylamine, yields,
by the action of nitrous acid, menthonyl alcohol (menthocitronellol),
C, H,,OH, which is a primary olefinic alcohol and is converted
by oxidation into an aldehyde (menthocitronellal), C,,H,,O. The
intimate relation of these two compounds with the olefinic cam-
phors occurring in nature is revealed by their similar odors. It
is, therefore, a matter of practical importance to artificially pre-
pare the olefinic camphors from the more accessible cyclic com-
pounds, since the former are to an extent very valuable perfumes.
For this reason a rapid extension of our knowledge in regard to
the olefinic terpenes and camphors.is to be expected, and it fol-
lows from this that more light will be thrown upon the constitu-
tion of the closed-chain terpenes and camphors.

1Bertram and Walbaum, Journ. pr. Chem., N. F., 45, 590.

2Tiemann and Semmler, Ber., 26, 2708.
sWallach, Ann. Chem., 278, 315.

30 THE TERPENES.

It has been the aim of the foregoing to somewhat facilitate the
study of the ten-carbon terpenes and their derivatives by a short
survey of this extensive field. It should, however, be especially
mentioned that to those who intend to study the chemistry of the
terpenes, a very valuable aid will be found by a careful examina-
tion of an address given by Wallach’ in the year 1891.

Although the investigations of Wallach have made possible a
systematic classification of the terpenes proper, C,,H,,, and the
work of this chemist, as well as of numerous others, has already
determined with a certain degree of accuracy the constitution of
some members of this group, nevertheless, nothing comparable with
this has yet been accomplished for the terpenes having five, fifteen,
and more carbon atoms. It should be noted, however, at this point
that Wallach? has made efforts to compile at least a classification
for the sesquiterpenes, C,,H,,. Still, this work has not been in
any degree as successful as in the analogous case of the terpenes,
C,,H,,- Several alcohols, C,,H,,OH, related to the sesquiter-

penes, are associated with the latter to some extent in their —

natural occurrence. For the remaining polyterpenes, reference is
made to the special part.

In the compilation of this monograph, it has been assumed that
only such material is to be accepted from the numerous. publica-

tions as possesses permanent value for science. The experience —

of past years has proved that structural formulas, which haye been
suggested in extremely large numbers for many members of the
terpene series, are often in a very short time rendered valueless
by facts. The time has not yet arrived when it is possible to
give an objective and hence scientifically valuable criticism of the
views expressed in these constitutional formulas, For this reason
it has been the design to presentall the constitutional formulas which
have been proposed for a few members of the terpene series. In
general, however, the structural formulas are only presented in the

consideration of those substances whose constitution has been de-

termined with certainty, or with a high degree of probability ; or

in certain cases where the presentation of a formula, which, al-
though not determined with scientific accuracy, can nevertheless

be used to more clearly illustrate the relation of several com-

pounds to one another.

In regard to the actual observations which have been -pub-

lished, the author has exerted himself to the utmost to present
them in a complete form. :

1Wallach, Ber., 24, 1525.
*Wallach, Ann. Chem., 271, 285 and 297.

‘

~

1 pel Per. 5 ie

SPECIAL PART.
Hemiterpenes, C,H,.

For the numerous isomeric hydrocarbons, C,H,, Beilstein’s
“ Handbuch der organischen Chemie” (third edition, Vol. I., page
131), may be consulted. Isoprene, however, stands in an espe-
cially close relation to the terpenes, and should be more closely
considered here.

Isoprene, C,H,.

If the oil obtained by the dry distillation of caoutchouec or
guttapercha be submitted to a fractional distillation, a distillate
is obtained which consists of isoprene. Williams,’ Bouchardat,?
Tilden,* Wallach,* Euler® and Mokiewsky*® have published in-
vestigations concerning this hydrocarbon.

Kuler ® prepared isoprene by the following method. 3-Methyl-
pyrrolidine, C,H,,NH, on treating with methyl iodide, yields a
compound, which, when distilled with potash, yields 2, 3, 5-trimeth-
ylpyrrolidine, C,H,,.NH. This again unites with methyl iodide,
giving a substance which, on distilling with potash, yields trimeth-

ylamine and isoprene. ‘The latter is given the constitution,

Pure isoprene® is regenerated from its dibromide by treatment
with zinc dust; it is very unstable, boils at 33.5° (impure isoprene
boils at 33° to 39°), has a specific gravity of 0.6989 at 0° and
0.6794 at 19°. It is polymerized on heating to 250° or 270°
into dipentene. When acted upon by concentrated hydrochloric
acid, a polymerization product resembling caoutchouc results, to-
gether with oily chlorides. Isoprene does not form compounds
with ammoniacal solutions of silver and cuprous salts; oxidation
with a chromic acid solution or with nitric acid converts it into
carbonic acid, acetic acid, formic acid and oxalic acid.

1Williams, Journ., 1860, 495.

2Bouchardat, Compt. rend., 80, 1446; 89, 1217; Bull. Soc. Chim., 1879,
577.

8Tilden, Journ. Chem. Soc., 1884 (45), 410; Journ., 1882, 410.

4Wallach, Ann. Chem., 227, 295.

5Euler, Ber., 30, 1989.

-®Mokiewsky, Journ. Russ. Phys. Chem. Soc., 30 (1898), 885; 32 (1900),
207.

31

32 THE TERPENES.

According to Bouchardat, it combines with dry halogen acids,
adding one and two molecules of the halogen hydride.

Isoprene hydrochloride, C,H,- HCl, boils at 85° to 91°, and has
a specific gravity 0.885 at 0°; when treated with silver oxide, it
yields an alcohol which possesses an agreeable odor, boils at 120°
to 130°, and is somewhat soluble in water. The hydrochloride
gives an oily dibromide when treated with bromine.

Isoprene dihydrochloride, C,H,-2HCI, boils at 143° to 145°, and
has the specific gravity 1.079 at 0°.

Isoprene hydrobromide, C,H,: HBr, boils at 104° to 108°, and
at 0° has the specific gravity 1.192.

According to Mokiewsky,' the action of an acetic acid solution
of hydrogen bromide on isoprene gives a hydrobromide, C,H,Br,
which boils at 66° to 67°, and has the specific gravity 1.3075 at
0° and 1.2819 at 20°. On treating this bromide with alcoholic
potash, an alcohol, C,H,,O, is formed ; it boils at 97° to 99°, and
has the specific gravity 0.8417 at 0° and 0.8242 at 20°.

Isoprene dihydrobromide, C,H,-2HBr, has the specific gravity
1.623, and boils at 175° to 180°.

Isoprene dibromide, C,H,Br,, is formed, together with an amy-
lene bromine derivative, by adding one molecular proportion of
bromine to a cold, ethereal solution of isoprene. It is a very un-
stable liquid, has a penetrating odor, boils at 90° to 94° at 12
mm. pressure, and easily chars. When treated with zinc dust it
yields 70 per cent. of pure isoprene. It combines with one mole-
cule of bromine with difficulty, forming the tetrabromide. On
oxidizing the dibromide with a one per cent. solution of potassium
permanganate, the corresponding glycol, C,H,Br,(OH),, is formed ;
it crystallizes from ether in long, colorless prisms, melts at 126.5°,
sublimes when heated above its melting point, and is converted
into isoprene by the action of zinc dust.

Isoprene tetrabromide, C,H,Br,, was first prepared by Tilden. It
is an oil which decomposes by distillation, but, according to Wal-
lach,’ it may be purified by distillation with steam. If the bro-
mide be covered with ammonia, and allowed to remain for a short
time at a low temperature, a white amorphous mass results, which
is insoluble in all solvents (Wallach). |

Isoprene dichlorhydrin, C,H,Cl,(OH),, is formed, together with
the chlorhydrin of trimethylene glycol, C,H,,ClO, by the action
of a cold, dilute solution of hypochlorous acid on isoprene; the
product is a yellowish-brown, viscous liquid, from which the two
compounds are isolated. The dichlorhydrin crystallizes from al-

1Mokiewsky, Journ. Russ. Phys. Chem. Soec., 32 (1900), 207.
2Wallach, Ann. Chem., 238, 88.

ISOPRENE DIBROMHYDRIN. 33

cohol, ether or benzene, melts at 82.5°, and, when heated with
: ter at 120°, forms a compound, C,H,Cl- OH, which melts at
_72.5° to 73°. The compound, C H,,C10, boils at 141°, and has
a specific gravity 1.0562 at 0°. |
4% _ Isoprene dibromhydrin, C,H,Br,(OH).,, is formed by treating iso-
e with hypobromous acid ; it crystallizes in hexagonal plates,
Bend melts at 86°. It is more fenalily prepared than the corre-
SE ponding chlorine derivative.

!

TERPENES PROPER, C,,H,,.
I. PINENE.

In its two physical isomeric modifications, the levorotatory and
the dextrorotatory, pinene forms a widely distributed constituent
of numerous ethereal oils. Before Wallach had recognized the
identity of the pinene derived from different sources, it was be-
lieved that an extremely large number of terpenes existed, and
were designated as terebentene (levo-pinene), australene (dextro-
pinene), eucalyptene, laurene, olibene, massoyene and others.
Wallach’s’ investigations then determined that all these sub-
stances contain pinene as their chief constituent, whose physical
and chemical properties are modified by the presence of larger or
smaller amounts of isomeric hydrocarbons, or oxygen-containing
compounds of the terpene series.

The ethereal oils, prepared from the different varieties of pines
and from various other coniferous plants, are especially rich in
pinene, hence the name. Thus, pinene is the chief ingredient of
turpentine oil ; the American, Russian, Swedish and German tur-
pentine oils contain dextro-pinene; the French oil consists al-
most wholly of levo-pinene.

The latter modification has also been found by Bertram and
Walbaum ? in the pine needle oils from Abies alba, Picea excelsa,
Pinus montana, and Pinus silvestris L.,> oil from cones of Abies
alba, and hemlock needle oil. Among the numerous oils in
which pinene occurs the following may be mentioned: pine
needle oil from Pinus silvestris,‘ oil of Siberian pine needles,’ oil
of pine-resin,° oil of juniper berries,’ oil of eucalyptus (Z. globu-
lus),? oil of mace,’ oil of sage,’ oil of lemon,’ oil of basil,®
oil of laurel berries and laurel leaves,” oil of olibanum,” valerian

1Wallach, Ann. Chem., 227, 282; 230, 245; 252, 94; 258, 340.
*Bertram and Walbaum, Arch. Pharm., 231, 290.

sSchimmel & Co., Chem. Centr., 1898, 258.

‘Bertram and Walbaum, Arch, Pharm., 231, 290.
5Flawitzky, Journ. pr. Chem., N. F., 45, 115.

®Kurilow, Journ. pr. Chem., N. F., 45, 123.

Wallach, Ann. Chem., 227, 282.

*Bertram and Walbaum, Arch. Pharm., 235, 176.

§Wallach and Gildemeister, Ann. Chem., 246, 283.

wWallach, Ann. Chem., 252, 94.

34

oe

PINENE. 35

oil, bay oil,‘ camphor oil, coriander oil, fennel oil, oil of massoy
bark,’ oil of myrtle,’ parsley oil, oil of rosemary, oil of spike,
oil of star anise, oil of thyme, oil of water fennel, oil from
sassafras bark and sassafras leaves,‘ and oil of valerian (Japan-
ese). The presence of pinene is also reported in the oils of gal-
banum, niaouli, canella, cheken leaves, French basilicum, tansy,
cajeput, kesso-root, spearmint, elderberry, thuja, nutmeg, pepper-
mint and lavender. Pinene is likewise found in the products re-
sulting from the dry distillation of vegetable resins. Thus,
Wallach and Rheindorf® recognized this hydrocarbon in the dis-
tillation products of copal resin, olibanum and colophonium.
Commercial resin oil also contains pinene as shown by Renard,’
who isolated from this product a levorotatory hydrocarbon hay-

ing the properties of pinene. Pinene also occurs in the distillation

products of resinous woods; an example may be cited in the in-
vestigations of Aschan and Hjelt,® who recognized it in the prod-
ucts of distillation of pine roots and trunks of the Scotch fir.
PREPARATION.—In order to prepare the optically active modi-
fications of pinene, we must resort to the fractional distillation of
the ethereal oils containing it. For the preparation of dextro-
pinene, it is most convenient to employ American oil of turpen-
tine, while for the preparation of levo-pinene, the French oil is’
best adapted. Should the oil at command be old, it must first be
distilled with steam, dried with potassium hydroxide and fraction-
ated, using some form of fractionating apparatus; the fraction
boiling up to 160° is to be further purified by repeated fraction-
ations. The product thus obtained is, of course, not strictly
pure. Chemically pure pinene is optically inactive, and may be
prepared by an excellent method suggested by Wallach ;° this
method is based on the fact that when pinene nitrosochloride is
heated with an excess of aniline, nitrosyl chloride is eliminated
with the formation of amido-azo-benzene and inactive pinene :

C,,H,,.NOCI + 2C,H,NH, = H,0 + HCl + C,H,N:NC,H,NH, + Cy His

Since it is not advisable to operate with too large quantities at
a time, ten grams of pinene nitrosochloride are heated for a

1Mittmann, Arch. Pharm., 227, 529.

2Wallach, Ann. Chem., 258, 340; Arch. Pharm., 229, 1.

sJahns, Arch. Pharm., 227, 174.

4Power and Kleber, Pharm. Review, 1896.

5Bertram and Gildemeister, Arch. Pharm., 228, 483.

6Wallach and Rheindorf, Ann. Chem., 271, 308.

TRenard, Ann. Chim. Phys. [6], 1, 223.

Aschan and Hijelt, Chem. Ztg., 18, 1566; compare Renard, Comp. rend.,
119, 165.

SWailach, Ann. Chem., 252, 132; 258, 343.

36 THE. TERPENES.

short time with a mixture of thirty cc. of aniline and eighty cc.
of alcohol in a flask provided with a vertical condenser. After the
violent reaction has taken place, the product is distilled with
steam. ‘The aqueous distillate is then treated with an excess of
acetic acid to remove the unchanged aniline, the hydrocarbon is
separated and again washed with acetic acid, and rectified.

Properties.—According to Wallach, chemically pure pinene,
obtained by the method just suggested, is an optically inactive
liquid, boiling at 155° to 156°. At 20° its specific gravity is
0.858; at 25° it is 0.854; its coefficient of refraction at 21° is
ny = 1.46553.

According to their sources, the optically active modifications
have a specific gravity of 0.8587 to 0.8600, and a rotatory
power, [2])= + 32° to [a]p = — 43.4°.

The spectrometric behavior of levo-pinene has been closely ex-
amined by Briihl.’

Before we consider more carefully the characteristics of
pinene, it would seem expedient to present a series of trans-
formations of pinene, which had been performed before Wal-
lach’s investigations; it is doubtful, however, whether all the
reaction-products obtained by these transformations result directly
from pinene.

If the vapor of oil of turpentine be passed through a tube heated
to redness, hydrogen, isoprene, C,H,, benzene, toluene, meta-
xylene, cymene, naphthalene, anthracene, methylanthracene,
phenanthrene, and terpilene (terpinene) are formed (G. Schultz’).
Pinene absorbs oxygen from the air forming acetic acid, hydrogen
peroxide,* and a compound resembling an aldehyde, and is even-
tually converted into a resinous mass. By the electrolysis of a
mixture of dilute sulphuric acid, oil of turpentine and alcohol, ter-
pine hydrate, terpine, cymene, and two acids are formed. Renard®
has examined some of the salts of these acids.

Nitric acid readily oxidizes turpentine oil, while fuming nitric
acid or a mixture of nitric and sulphuric acids ignites it. A series
of products have been obtained by the action of dilute nitric acid
on oil of turpentine ; among these may be mentioned acetic acid,
propionic acid, butyric acid, an acid of the formula, C,H,O,, di-
methyl fumaric acid, C,H,O,, oxalic acid, para-toluic acid, C,H,O,,
terephthalic acid, C,H,O,, terebic acid, C,H,,O,, terechrysinic

1Kannonikow, Ber., 1881, 1697.

*Briihl, Ber., 25, 153.

8G. Schultz, Ber., 1877, 114; compare Tilden, Journ. Chem. Soce., 45, 411.

4Kingzett, Jahresb. Chem., 1876, 402.

5Renard, Jahresb. Chem., 1880, 448.

NR ai ala

os

mage hye — -

Te Fa 9

“ty

PINENE. 37

acid, C,H,O,, and nitro-benzene.* Chromic acid solution oxidizes
turpentine oil into acetic acid, terebic acid, terperlylic acid,
C,H,,O,, and a little terephthalic acid.’

"Reducing agents, such as phosphonium iodide at 300°,” hydriodic
acid and red phosphorus at 275°,° and a hydriodic acid solution
of specific gravity 2.02 at 280°,! convert pera oil into the
phat C,,H,, or C,,H,, (b. p. 165°), C,,H,, (b. p. 170° to
175°), C,,H,, (b. p- 155° to 162°), pee C,H, , (b. p- 40°). When
heated with iodine at 230° to 250°, meta-xylene, a little para-
ih and cymene, pseudocumene, mesitylene, a hydrocarbon,

H,, (b. p. 189° to ne durene and polyterpenes, (C,,H,,),,
are formed.

To return to the ieisidaredion of pure pinene, we find that it is
distinguished by the readiness with which it can be converted into
isomeric terpenes. The transformation into the closely related
camphene can be accomplished either by the action of concentrated
sulphuric acid, or by passing dry hydrogen chloride into dry
pinene, and heating the pinene hydrochloride thus formed with
sodium acetate, or aniline. On the other hand, the action of
moist hydrochloric acid forms dipentene dihydrochloride, which,
by elimination of the hydrogen chloride, yields dipentene. A
direct transformation of pinene into dipentene can, however, be
effected by heating pinene to 250° to 270°.°

Dilute nitric® or sulphuric acid converts pinene into dipentene
and terpine hydrate.

According to Wallach, the terpenes, terpinolene and terpinene, i
resulting by the action of alcoholic sulphuric acid on pinene, are
not to be considered as the primary products of the reaction, but
rather as resulting from a transformation of dipentene, which is
first formed.

According to Genvresse,* when a mixture of pinene, alcohol
and nitrous acid (purified from nitric acid) is left at the ordinary
temperature, reaction takes place slowly, and at the end of two
months about two-thirds of the pinene is changed. By fractional
distillation of the product, a liquid is obtained which is identical

1Roser, Ber., 1882, 293; Fittig and Kraft, Ann. Chem., 208, 74; compare
publications of Schryver, Journ. Chem. Soc., insaaed (1), 1327; Ber., 27,
133 Ref.

*Baeyer, Ann. Chem., 155, 276.

8Orlow, Journ. Russ. Phys. Chem. Soc., 15, 44; Ber., 16, 799.

4Berthelot, Journ., 1869, 332.

5Wallach, Ann. Chem., 227, 282.

‘Hempel, Ann. Chem., 180, 73.

TWallach, Ann. Chem., 227, 282; 230, 262.

8P. Genvresse, Compt. rend. (1901), 132, 637.

38 THE TERPENES.

with terpineol ; the yield is about seventy-five per cent. of the
pinene transformed. The melting point of its nitrosochlorideis 83°.

Pinene picrate, C,,H,,-C,H,(NO,),OH, is prepared, according
to Lextreit,' by heating pinene with picric acid at 150° ; it forms
erystals, which, by boiling with potassium hydroxide, yield in-
active borneol. Camphene is obtained by heating the compound
with pyridine, or by dry distillation of its potassium salt (Tilden
and Forster ’).

Pinene hydrochloride,’ C,,H,,- HCl (so-called “ artificial cam-
phor”), is obtained by saturating well cooled, dry pinene with
dry hydrochloric acid gas. If rise of temperature during the
operation is prevented, the oil solidifies almost completely after
saturation with the gas to a camphor-like mass. It is necessary
to avoid the presence of moisture and to prevent the rising of the
temperature, as otherwise some dipentene dihydrochloride is
formed, and prevents the complete solidification of the reaction-
product; for, as Tilden‘ first observed, pinene hydrochloride and
dipentene dihydrochloride form a mixture, which has a low melt-
ing point.

Pinene hydrochloride is very volatile at ordinary temperature,
and smells like camphor. It crystallizes from alcohol in feathery
crystals, which press together, forming a sticky mass. It melts
at about 125°, and boils at 207° to 208°, suffering almost no de-
composition (Wallach).

The hydrochloride of dextro-pinene is optically inactive accord-
ing to the observations of Pesci,’ which have been confirmed by
Wallach and Conrady ; that prepared from levo-pinene is leyo-
rotatory, [a] ,—= — 30.687° and — 26.3°.

According to more recent investigations by J. H. Long,’ pinene
hydrochloride melts at 131° and not at 125°, and the different
values (from 0° to + 30°), which have been given by different
investigators for the specific rotatory power of the hydrochloride,
are due to the fact that the hydrocarbon employed contained vary-
ing amounts of dextro- and levo-pinene. Long finds that the
hydrochloride of levo-pinene has a higher rotatory power than
l-pinene, and that the hydrochloride from dextro-pinene has a
slightly lower rotatory power than d-pinene.

1Lextreit, Compt. rend., 102, 555; Ber., 19, 237, Ref.
“Tilden and Forster, Journ. Chem. Soc., 1893 (1), 1388; Ber., 27, 136, Ref.
SWallach, Ann. Chem., 239, 4; compare J. Kondakow, Chem. Zeit., 25
(1901), 609.
‘Tilden, Ber., 12, 1131.
oe Gazz. Chim., 1888, 223; Wallach and Conrady, Ann. Chem., 252,
‘John H. Long, Journ. Amer. Chem. Soc., 21, 637.

a ee hee a

PINENE HYDROBROMIDE. 39

Camphene' is formed when pinene hydrochloride is heated
to 200° with sodium acetate and acetic acid; according
to earlier experiments of Ribau and Berthelot, the same re-
sult can be obtained by heating with alcoholic potash, or other
reagents capable of eliminating the elements of hydrogen chloride.
The latter reactions require, however, a relatively high tempera-
ture.

Armstrong’ regards the hydrochloride as more closely related
to camphene than to pinene, and, since it may be converted into
dihydrocamphene,’ C,,H,, (which he calls camphydrene), by the
action of sodium and alcohol, he introduces the term chlorocam-
phydrene for this hydrochloride.

By oxidizing one part of the hydrochloride with five parts of
concentrated nitric acid at a temperature of about 20°, Armstrong ‘
obtained ketopinie acid, C,,H,,O,, which crystallizes from water in
colorless plates, melting at 234°, and is optically inactive; its
hydrazone melts at 146°, and its oxime fuses at 216°.

When the hydrochloride is oxidized on the water-bath with
nitric acid diluted with half its volume of water, it is converted
into acetic acid, camphoric acid, C,,H,,O,, camphopyric or cam-
phoie acid, and other acids.°

According to Wagner,’ pinene hydrochloride is the true chlo-
ride of borneol ; this view is also supported by Semmler.* At-
tempts to convert the hydrochloride into bornyl acetate by heat-
ing with silver acetate and acetic acid gave camphene and
isobornyl acetate, but no borny!] acetate.

Tetrahydropinene, C,,H,,, was obtained by Wallach and Berk-
enheim’ as a reduction product of pinene by heating pinene hy-
drochloride to 200° with hydriodic acid and red phosphorus. It
boils at 162°, has the specific gravity 0.795, and the refractive
index 1.437 at 20°.

Pinene hydrobromide, C,,H,,-HBr, was first obtained by De-
ville.® It is prepared by the action of dry hydrobromic acid on
pinene, and melts at about 90°; it boils with decomposition. It
resembles the hydrochloride in its optical behavior, and, like this,

1Wallach, Ann. Chem., 252, 6.

Armstrong, Journ. Chem. Soc., 69 (1896), 1398.

3Semmler, Ber., 33, 774.

Armstrong, Journ. Chem. Soc., 69 (1896), 1401.

5Gardner and Cockburn, Journ. Chem. Soc., 73 (1898), 278.

6Wagner and Brickner, Ber., 32, 2302.

TWallach and Berkenheim, Ann. Chem., 268, 225.

8Deville, Ann. Chim. Phys., 75, 45 and 54; compare Papasogli, Gazz.
Chim., 1876, 542.

40 THE TERPENES.

is converted into camphene by the elimination of hydrogen bro-
mide (Wallach *).

Pinene hydriodide,? C,,H,,-HI, is best prepared by the ac-
tion of dry hydrogen iodide on French turpentine oil. It is
a stable, heavy, colorless oil, boils at 118° to 119° under a
pressure of 15 mm., solidifies in a freezing mixture, melts at
— 3° and has the specific gravity 1.4826 at 0° and 1.4635 at
20° (Wagner *).

When prepared from a turpentine oil having a specific rotatory
power, [a], = — 37° 50’, and washed with aqueous caustic pot-
ash, it had the rotatory power, [2], = — 33° 34’, in a one deci-
meter tube ; on heating with alcoholic potash, this value decreased
until after forty hours of this treatment the value was [a])=
— 31° 25’.

It is converted into camphene by heating with alcoholic potash
at 160° to 170° for a short time. It is only slowly attacked by
a hot solution of potassium permanganate, but is readily oxi-
dized by fuming nitric acid in the cold with elimination of iodine.
When treated with silver acetate and acetic acid, it is con-
verted into a mixture of dipentene, terpinyl acetate, camphene, ~
bornyl acetate, and isobornyl acetate; Wagner* regards the two
first-mentioned compounds as the normal products of the action,
while camphene and isobornyl acetate are produced in larger
quantities at higher temperatures, and are regarded as secondary
products.

Wagner regards pinene hydriodide as identical with bornyl
iodide in all respects except its rotatory power.

The Action of Hypochlorous Acid on Pinene.*

When French turpentine oil, boiling at 155° to 156° and
having the specific rotation, [a],— — 37° 30’, is treated with
hypochlorous acid, and the resulting product is acted upon by
potash, a mixture is obtained from which Wagner® has isolated
the following compounds : cis-pinole oxide (Wallach’s anhydride
of pinole glycol), C,,H,,O,, cis-sobrerytrite (menthane-1, 2, 6, 8-
tetrol), C,,H,,O,, cis-pinole glycol-2-chlorhydrin, C,,H,,O-Cl(OH),
cis-menthane-1, 2-dichlor-6, 8-diol, C,,H,,O,Ol,, a chlorhydrin of

1Wallach, Ann. Chem., 239, 7.

*Deville, Ann. Chem., 37, 176; Baeyer, Ber., 26, 826.

sWagner and Brickner, Ber., 32, 2302.

‘Wagner and Slawinski, Ber., 32, 2064; Wagner and Ginzberg, Ber., 29,
886; Ginzberg and E. Wagner, Journ. Russ. Chem. Soc., 30, 675.

5Wagner and Ginzberg, Ber., 29, 886.

PINENE NITROSOCHLORIDE. 41

unknown composition, nopinole glycol, C,,H,,O,, and unsaturated
compounds. .

Only nopinole glycol will be considered here; the remaining
compounds, being derivatives of pinole, will be mentioned more in
detail under pinole.

Nopinole glycol, C,,H,,O,, is regarded by Wagner as a derivative
of an isomeride of pinene ; it crystallizes from ether in splendid
prisms, and melts at 126° to 127°. It differs from the pinole
glycols in that its diacetate is a liquid, and it gives a red colora-
tion with concentrated sulphuric acid, while the pinole glycols at
first give a light yellow color which passes into a bright red.
When oxidized with permanganate, it yields formic acid and a
non-volatile, syrupy acid, but no acetic acid; under similar con-
ditions the pinole glycols give acetic and terpenylic acids.

When an emulsion of pinene in water is treated with hypo-
chlorous acid and the product is treated with potassium carbonate,
a compound,’ C,,H,,Cl,, which Wagner calls tricyclene dichloride,
is produced ; it melts at 165° to 168°.

Additive Compound of Formaldehyde and Pinene.’-—A compound,
C,,H,,O, is obtained by heating twenty grams of pinene, 4.4—
grams of paraformaldehyde and ten grams of alcohol in a sealed
tube at 170° to 175° for twelve hours; the contents of the tube
are poured into water, extracted with ether, and distilled. Con-
siderable unchanged terpene is recovered, together with an oil
boiling at 225° to 240°. After purification by steam distillation,
it boils at 232° to 236°, and has the composition C,,H,,O. It
is a clear, strongly dextrorotatory liquid, and is readily soluble
in most solvents, but insoluble in water; it has a specific gravity
of 0.961 at 20°, and a turpentine-like odor. It forms a dihydro-
chloride melting at 74°, a dihydrobromide melting at 77°, and
liquid acetyl- and benzoyl-derivatives.

The action of nitrous acid upon pinene, see pinenol, C,,H,,OH.

Pinene nitrosochloride, C,,H,, - NOCI, was discovered by Tilden,”
who obtained it by passing nitrosyl chloride into a mixture of
pinene and chloroform, the liquid being cooled by a freezing mix-
ture. Later, Goldschmidt‘ investigated this compound, and pre-
pared from it nitrosopinene (see below). The importance of
pinene nitrosochloride and similar products prepared from other ter-
penes for the characterization of the terpenes was recognized by

1Ginzberg and E. Wagner, Journ. Russ. Chem. Soc., 30 (1898), 675.

20. Kriewitz, Ber., 32, 57.

8Tilden, Jahresb. Chem., 1874, 214; 1875, 390; 1877, 427; 1878, 979;
1879, 396. ,

4Goldschmidt, Ber., 18, 2223.

42 THE TERPENES.

Wallach, who studied especially the pinene nitrolamines resulting
from pinene nitrosochloride. Although Wallach gives the above
suggested simple formula for this substance, Baeyer* considers it
as a bisnitrosyl-derivative :—

Cy oH.Cl <> N,0, — C,9H,,Cl.

Wallach? recommends the following method for the preparation
of this compound.

To a mixture of fifty grams each of oil of turpentine, acetic
acid, and ethyl nitrite, well cooled by a freezing mixture of salt
and ice, add gradually fifteen cc. of crude, thirty-three per cent.
hydrochloric acid. -Pinene nitrosochloride separates at once as a
crystalline precipitate, which is filtered with the pump and puri-
fied by washing with alcohol. After standing in a cool place, and
especially on the addition of alcohol, more pinene nitrosochloride
separates from the filtrate. The filtrate from pinene nitroso-
chloride, when distilled with steam, yields pinole. .

If carefully washed with alcohol, pinene nitrosochloride can be
immediately used for the preparation of pure pinene, or of the
following derivatives. A more perfect purification may, however,
be accomplished by solution in chloroform and subsequent pre-
cipitation with methyl alcohol. Thus purified, the product may
then be recrystallized from benzene. Pure pinene nitrosochloride
melts at 103° (according to Schimmel & Co.,> it melts at 108°).
This compound and its derivatives are optically inactive. Baeyer*
found that carvoxime hydrochloride is formed by allowing a solu-
tion of pinene nitrosochloride in ethereal hydrochloric acid to
stand for a long time.

Pinene nitrosobromide, C,,H,,.NOBr, is obtained by a similar
process, It melts at 91° to 92° with decomposition (Wallach °).

Pinene Nitrolamines.

Pinene nitrolpropylamine® melts at 96°.

Pinene nitrolamylamine® melts at 105° to 106°.

Pinene nitrolallylamine® melts at 94°.

Pinene nitrolpiperidide’ is formed when pinene nitrosochloride is
dissolved in excess of an aqueous or alcoholic solution of piperi-

iBaeyer, Ber., 28, 648.

*Wallach, Ann. Chem., 253, 251; 245, 251.

3Schimmel & Co., Semi-Annual Report, April, 1901, 11.
4Baeyer, Ber., 29, 3.

Wallach, Ann. Chem., 253, 251.

6Wallach and Friistiick, Ann. Chem., 268, 216.
TWallach, Ann. Chem., 245, 251.

NITROSOPINENE. 43

dine, and gently warmed. When the energetic reaction is com-
plete, the resulting nitrolamine is precipitated by the addition of
water. It melts at 118° to 119°.

Pinene nitrolbenzylamine’ is obtained by the action of an aleo-
holic solution of benzylamine (two molecules) on pinene nitroso-
chloride. It separates from a mixture of ether and alcohol in
beautiful, hemihedral, rhombic crystals, melting at 122° to 123°.

Dextro- and levo-pinene yield the same optically inactive
nitrolamines. When heated to a rather high temperature, the
pinene nitrolamines decompose into a polymeric modification of
nitrosopinene and the corresponding primary base ; for example,
pinene nitrolbenzylamine, when heated to 160°° to 180° in a
paraffin bath, decomposes, yielding benzylamine.

Although Wallach ascribes to the pinene nitrolamines the for-
mula,

JNO
Ci rR

Baeyer considers them as constituted similar to pinene nitrosochlo-
ride:
NHR RHN

It should be mentioned that secondary amines, for example
diethylamine, convert pinene nitrosochloride into nitrosopinene.
On the other hand, as has already been mentioned, aniline and
other aromatic bases convert it into inactive pinene, with a simul-
taneous formation of amidoazo-compounds.

Nitrosopinene, C,,H,,NO, was obtained by Tilden” by the ac-
tion of alcoholic potash on pinene nitrosochloride : |

C,H, ,NOCI + KOH = C,,H,,NO + KCl + H,0.

Wallach and Lorentz * give the following method for the prep-
aration of nitrosopinene.

To a solution of twelve grams of sodium in thirty cc. of
ninety per cent. alcohol, add one hundred grams of pinene ni-
trosochloride. Boil the mixture on the water-bath, using a re-
flux condenser, until all nitrosochloride has entered into the
reaction. Then add sufficient water to the liquid to dissolve the
sodium chloride, which is thrown out; filter off any impurities
which may appear, and pour the clear liquid into a large excess of

1Wallach, Ann. Chem., 252, 130.
2Tilden, Jahresb. Chem., 1875, 390.
3Wallach and Lorentz, Ann. Chem., 268, 198.

44 THE TERPENES.

water acidified with acetic acid. Nitrosopinene is at first thrown
out as an oil, but after standing for several days it solidifies to
a very hard, yellowish mass. This is broken up, thoroughly
washed with water and dried on a porous plate. The most con-
venient method of purification is to rub up the crude product with
petroleum ether, in which nitrosopinene is sparingly soluble; an
absolutely pure product is obtained by reerystallization from
ethyl acetate in the form of monoclinic crystals,’ melting at 132°.

Nitrosopinene is optically inactive. Alcoholic hydrochloric
acid converts it into carvoxime hydrochloride.”

As a result of their observations that nitrosopinene forms a
sodium salt and a methyl ester, Goldschmidt and Zuerrer® classify
this substance as an isonitroso-compound, C,,H,,—NOH, whilst
Wallach‘ is inclined to regard it as having the constitution of a
true nitroso-compound, C,,H,,NO. :

The statements on which Wallach bases his views, and in ac-
cordance with which nitrosopinene should be very stable towards
acids, are faulty, according to Baeyer,’ and the latter investiga-
tor agrees with Goldschmidt in ascribing the isonitroso-structure
to nitrosopinene.

Meanwhile, however, Urban and Kremers® mentioned in a pre-
liminary publication, that when nitrosopinene is boiled with hy-
drochloric acid, the product consists of hydroxylamine and an oil.
According to Baeyer,’ carvacrol and hydroxylamine are formed
by long-continued boiling of nitrosopinene with hydrochloric
acid. Mead and Kremers’ have also obtained the same result.

When nitrosopinene is reduced with zinc dust and acetic acid,
it yields a mixture of pinocamphone, C,,H,,O, and pinylamine,
C,,H,,NH,.2 Cymene is readily formed by the distillation of
pinylamine hydrochloride. The same hydrocarbon is likewise
obtained by the elimination of hydrogen bromide from pinene
dibromide. Nitrosopinene unites with bromine forming nitroso-
pinene dibromides.

Behavior of Pinene toward Bromines,

Although the action of bromine on pinene has been the subject
of much study, very divergent results have been obtained. Wal-

1Maskelyne, Jahresb. Chem., 1879, 396; Hintze, Ann. Chem., 252, 133.
2Baeyer, Ber., 29, 3. :
8Goldschmidt and Zuerrer, Ber., 18, 2223.

4Wallach, Ber., 24, 1547.

5Baeyer, Ber., 28, 646.

‘Urban and Kremers, Amer. Chem. Journ., 16, 404; Ber., 27, 793, Ref.
™Mead and Kremers, Amer. Chem. Journ., 17, 607.

® Wallach, Ann. Chem., 258, 346; 268, 197; 300, 287; $18, 345.

CRYSTALLIZED PINENE: DIBROMIDE. 45

lach’s investigations’ have shown that the various reactions are
extremely complicated, a condition which the varying results of
the investigations of Oppenheim,’ Tilden * and others have suffi-
ciently explained.

If dry bromine be added drop by drop to well cooled, abso-
lutely dry pinene, diluted with pure carbon tetrachloride, two atoms
of bromine are united to one molecule of pinene, accompanied by
an immediate removal of the color of the bromine. If more
bromine be added, the color of the bromine will disappear
quickly or slowly, according to the conditions under which the
experiment is performed, especially the temperature. However,
the facts that the decolorization is not immediate, and that it is
accompanied by an evolution of hydrogen bromide, prove that a
simple addition no longer takes place. The absorption of four
atoms of bromine can be accomplished in this manner.‘

The course of the reaction is, however, further complicated
since the elimination of hydrogen bromide can be observed even
in the first phase of the interaction. The hydrogen bromide so
formed also reacts on some unchanged pinene, forming the mono-
hydrobromide.

In accordance with the above-described method, if two atoms
of bromine be added to one molecule of pinene, and, after
removal of the carbon tetrachloride, the reaction-product be
boiled with alcoholic potash, two reaction-products are obtained:
an oil boiling in vacuum at 80° to 140°, and a solid pinene
dibromide. .

The oil boiling at 80° to 140° contains bromine, and on boiling
with aniline yields a large quantity of camphene. This hydro-
carbon probably results from the pinene hydrobromide, which is
formed during the bromination of pinene, and which is stable
towards alcoholic potash at low temperatures. When this liquid
pinene dibromide is reduced with alcohol and sodium, dihydro-
camphene, C,,H.,,, is obtained.®

Crystallized pinene dibromide, C,,H,,Br,, is obtained by the
bromination of pinene according to the above method, the yield
amounting to about seven per cent. of the pinene used. It is re-
covered from the residues, which remain after distilling off the
lower boiling products, by recrystallization from alcohol.

1Wallach, Ann. Chem., 264, 1.

2Oppenheim, Ber., 5, 94 and 627.

8Tilden, Journ. Chem. Soc., 1888, 882; Ber., 22, 135; Journ. Chem. Soc.,
69 (1896), 1009.

*Stschukareff, Journ. pr. Chem., N. F., 47, 191; see also Tilden, Journ.
Chem. Soc., 69 (1896), 1009.

5Semmler, Ber., 33, 3420.

46 THE TERPENES.

This substance crystallizes from alcohol or from acetic ether
and chloroform, in which it is more easily soluble, in character-
istic, hexagonal crystals, whose faces are almost never sharply de-
fined, but grow pyramid-shaped and are often hollow. Pinene
dibromide melts at 169° to 170°, and is optically inactive.

When heated with aniline in a sealed tube at 180° it readily
yields cymene.

According to Wagner,’ this pinene dibromide, melting at 169°
to 170°, may be more readily obtained and in a larger quantity
by the action of hypobromous acid on pinene.

Wagner? also states that when pinene dibromide, melting at
169° to 170°, is treated with zine dust and acetic acid, it is con-
verted into a new terpene, melting at 65° to 66° and boiling at
153°; he terms this hydrocarbon, tricyclene.

Pinene dichloride (?), C,,H,,Cl,_A compound, C,,H,,Cl,, which
is called tricyclene dichloride,’ is formed by adding hypochlorous
acid to an emulsion of pinene in water, treating the product with
potassium carbonate, extracting with ether, and distilling with
steam. It crystallizes in monoclinic crystals, and melts at 165°
to 168°.

Oxidation of Pinene.

4

Two neutral reaction-products have been found by G. Wagner
to result from the action of a one per cent. solution of potassium per-
manganate on pinene at 0°. ‘These substances are separated by
repeated fractionation in vacuum.

1. Pinene glycol, C,,H,(OH),.—The higher boiling of these
two substances is regarded by Wagner as pinene glycol. It boils
at 145° to 147° under 14 mm. pressure, and at 150° to 152°
under 21 mm. It is a “fairly solid, crystalline, extremely hy-
groscopic mass,” which apparently has not been obtained quite
free from the adhering mother-liquors. A homogeneous com-
pound does not appear to have been isolated, although it should
be added that Wagner separated a compound, melting at 76° to
78°, which he regards as the pure glycol ; it does not react with
hydroxylamine or ammoniacal silver solution.

The transformation which this substance undergoes when
heated with very dilute hydrochloric acid should be mentioned.
One of the products is an oil which is volatile with steam, and
boils at 180° to 220° ; the chief portion boils at 180° to 190°

1G. Wagner and Ginzberg, Ber., 29, 886.

2G. Wagner and Godlewski, Journ. Russ. Chem. Soc., 29 (1896), 121.
3Ginzberg and E. Wagner, Journ. Russ. Chem. Soc., 30 (1898), 675.
4G. Wagner, Ber., 27, 2270.

fag NR 6-7 23

PINONONIC ACID. A7

and is composed chiefly of pinole (when treated with bromine it
yields pinole bromide, melting at 92° to 93°), while the smaller
quantity of the higher boiling fractions contains a ketone of un-
known composition, which yields a crystalline oxime. The other
product is non-volatile with steam, forms quadratic tablets, melt-
ing at 191° to 191.5°, has the composition, C,,H,,O,, and is
probably an a-glycolene.

2. Keto-alcohol, C,,H,,O,.—The substance, formed together
with pinene glycol, boils at 122° to 124° under 14 mm. pres-
sure, and at 130° to 132° under 21 mm.; after remaining some
time, it deposits crystals, which melt at 97° and have the empir-
ical composition, C,,H,,O,. Wagner regards it as a keto-alcohol,
although it does not react with carbanile ; it gives a crystalline
oxime, C,,H,,(NOH),, which melts at 130°.

When this compound is allowed to remain in contact with
silver oxide, it is converted into pinononic acid,' C,H,,O,.

A third neutral product of the oxidation of French turpentine
oil is described by Wagner’ as an aldehyde, which is oxidized by
the air to an acid resembling camphenilic acid, C,,H,,O,, melt-
ing at 171.5° to 172.5°, which is obtained from camphene.

Wagner * has also described two acids resulting from the oxida-
tion of French turpentine with a one per cent. solution of per-
manganate at 0°.

1. Pinononic acid, C,H,,O,.—It crystallizes from chloroform in
transparent prisms, melts at 128° to 129°, is sparingly soluble in
cold water, and insoluble in petroleum. It yields an oxime, which
separates from water in plates and melts at 178° to 180°. Alka-
line hypobromite converts pinononic acid into an acid, C,H,,0,,
melting at 173° to 174°, bromoform, and carbon tetrabromide
(see norpic acid).

2. An acid separating from water in fine crystals, and melting
at 103° to 104° ; it is not a ketonic acid.

As a result of his investigations on pinene, Wagner’ proposed
the following formula for this terpene,

H, a CH,
H,C—C—CH,
eee n"
ae H
Hy,

In the critical consideration of the constitutional formulas of

1G. Wagner and Ertschikowsky, Ber., 29, 881.
*G. Wagner, Ber., 27, 1636.

48 THE TERPENES.

pinene, and other members of the terpene series, which have
been advanced by G. Wagner during the course of his investiga-
tions above referred to, the incompleteness of the experimental
foundations for these formulas, as is sufficiently observed from
what has been mentioned, must not be neglected.

Tiemann and Semmler' have published accounts of their re-
searches in regard to the action of potassium permanganate on
pinene. They isolated the following compounds :

d-Pinonic acid, C,,H,,O,.—This is prepared by gradually adding
a solution of seven hundred grams of potassium permanganate in
six liters of water to an emulsion of three hundred grams of
pinene in two litersof water. The filtered liquid is evaporated to
about two liters, saturated with carbon dioxide, and the neutral
compounds are removed either by distillation with steam or by
extraction with ether. The crude pinonic acid is separated from
its potassium salt by sulphuric acid, and is extracted with ether.
According to the conditions of temperature which prevail during ©
the oxidation, the products are different, but they may be entirely
controlled ; thus, when the temperature is maintained at about 6°,
a liquid pinonic acid results, while at 25° to 40°, Baeyer’s
a-pinonic acid, melting at 103° to 105°, is the chief product.”

The liquid pinonic acid, which is to be regarded as a mixture
of isomerides,’ boils at 193° to 195° under 22 mm. pressure, while
at ordinary pressure it distills with slight decomposition at 310°
to 315°. When a crystal of a-pinonic acid is introduced into the
liquid pinonic acid, one-half of the weight of the latter is con-
verted into the solid a-pinonic acid.

Liquid pinonic acid, when freshly distilled, has the speci-
fic rotatory power, [a], = + 6°, in a one decimeter tube, but
this is increased to (2 p= + 13°, when all of the a-pinonic
acid is removed ; the latter acid has the specific rotatory power,
[4]>= + 2°, in a one decimeter tube, which is probably due to
imperfect separation of all of the liquid d-pinonic acid. !

According to Tiemann and Semmler,' this liquid pinonie acid is
a saturated ketonic acid, and forms two isomeric oximes; one of
these melts at 125° with loss of water, the other melting at 160°
without elimination of water. Its semicarbazone’ melts at 207°.

It yields the keto-lactone, C,,H,,O, (methoethylheptanonolide),
melting at 63° to 65°, when treated with acids, or when slowly
distilled at atmospheric pressure.”

1Tiemann and Semmler, Ber., 28, 1344 and 1778.
?Tiemann and Semmler, Ber., 29, 529.
3¥, Tiemann, Ber., 29, 119.

PINOLIC ACID. 49

It is slowly acted upon by an alkaline hypobromite solution
with the formation of bromoform.

1-Pinonic acid,’ C,,H,,O,, is a ketonic acid formed together with
a-dioxydihydrocampholenic acid, by the oxidation of a-campho-
lenie acid, C,,H,,O, (oxycamphor), boiling at 256°. It is also
produced by the dry distillation of a-dioxydihydrocampholenic
acid, C,,H,,O,, water being split off.

1-Pinonic acid crystallizes from water, and melts at 98° to 99°,
forming a colorless oil, which boils at 178° to 180° under 12 mm.
pressure. It has the specific rotatory power, [a], = — 21.4°.
It yields an oxime, melting at 147°, and a semicarbazone, melting
at 232°. It is acted upon by alkaline hypobromite with forma-
tion of bromoform or carbon tetrabromide. It is converted by
concentrated sulphuric acid into the keto-lactone, C,,H,,O, (meth-
oethylheptanonolide), which in this case appears to be optically
active.

i-Pinonic acid,’ C,,H,,O,, is formed, together with some liquid
d-pinonic acid, by the oxidation of French turpentine oil with a
dilute solution of potassium permanganate, at a temperature not
exceeding 30°. The solid, optically inactive acid is separated by
filtration from the active liquid acid, and is purified by recrystal-
lization from water; it melts at 105°, and is to be regarded as
identical with Baeyer’s a-pinonic acid. Its semicarbazone melts
at 206° to 207°.

i-Pinolic acid,? C,,H,,O,, is an alcoholic acid formed by the re-
duction of the solid i-pinonic acid or a-pinonic acid (m. p. 105°).
It is prepared by heating either of these solid pinonic acids with
alcoholic potash for six or seven hours at 185° to 200° ; it erys-
tallizes in needles, melting at 99° to 100°. It boils at 195° to
205° (20 mm.), is sparingly soluble in hot or cold water, dissolves
readily in alcohol, ethyl acetate or ether, and yields the crystalline
i-pinonic acid on oxidation with potassium! permanganate ; the
semicarbazone of the pinonic acid thus formed melts at 206° to
207°.

1-Pinolic acid,’ C,,H,,O,, is prepared from the liquid d-pinonic
acid in the same manner as i-pinolic acid from the crystalline a-
or i-pinoniec acid. It crystallizes in well formed needles, melting
at 114° to 115°. Ina thirty-three per cent. alcoholic solution it
has a rotation —7° ina 100 mm. tube. On oxidation with per-
manganate it is reconverted into the liquid d-pinonic acid, which
yields a semicarbazone, melting at 206° to 207°.

1F, Tiemann, Ber., 29, 3006.
2¥, Tiemann, Ber., 30, 409; 33, 2662.
4

50 THE TERPENES.

i-Pinocampholenic acid,’ C,,H,,O,, is formed when crude i-pino-
lic acid, which has not been subjected to treatment with a current
of steam, is distilled under reduced pressure ; the distillate also
contains pinodihydrocampholenolactone (see below). It is an oily
liquid having a faint odor, boils at 140° to 141° (13 mm.), has a
sp. gr. 0.9925 at 17°, and a refractive index, np = 1.46702. It
yields inactive pinodihydrocampholenolactone when treated with
hydriodic acid, and yields the same products on oxidation with
permanganate as a-campholenic acid, namely, 1-pinonic acid,
whose semicarbazone melts at 232°.

1-Pinocampholenic acid, C,,H,,O,, is prepared from the liquid
d-pinonic acid or the ]-pinolic acid in the same manner as the
preceding compound is obtained from i-pinonic or i-pinolic acid.
It boils at 136° to 138° (10 mm.), and at 248° to 252° under
atmospheric pressure. Sp. gr. is 0.9897 at 20°, n, = 1.47096,
In other properties it is identical with the inactive acid ; thus re-
duction converts it into the inactive lactone, and oxidation with
permanganate gives rise to l-pinonic acid (semicarbazone melting
at 231° to 232°), which, in turn, is oxidized by chromic and sul-
phuric acids yielding isocamphoronic acid (m. p. 166°) (Tie-
mann).

Pe asemee ee C,,H,,O., is obtained by the re-
duction of both pinolic acids and pinocampholenic acids with hydri-
odic acid ; it is a colorless oil, boils at 128° to 130° (12 mm.), and
at 254° to 257° under atmospheric pressure. Sp. gr. is 1.014 at
18°, n, = 1.4640. When hydrolyzed, it yields an oxy-acid which
does not crystallize, but on distillation yields crystalline i-pinolic
acid (m. p. 99° to 100°) (Tiemann).

According to Tiemann, pinolic acid, pinocampholenic acid and
pinodihydrocampholenolactone, which result from pinonic acid,
have the same chemical structure as oxydihydrocampholenic acid,
a-campholenic acid and dihydrocampholenolactone which may be
converted into pinonic acid. The differences in the behavior of
the oxy-acids, as well as in the melting points of the members of
both series and of their various derivatives, are to be explained by
the assumption of a condition of cis- and cis-trans-isomerism. Thus
the close relations existing between the constitution of pinene and
that of camphor are emphasized, for it is not only possible, start-
ing from a-campholenic acid, C,,H,,O,, to arrive at the optically
active l-pinonic acid, but also to convert members of the pinene
series into derivatives of the camphor series.

For the crystallographic relations of the pinonic acids, see
Fock, Zeit. Kryst. Min., 31 (1899), 479.

IF. Tiemann, Ber., 33, 2665.

Pe? or9 2

DIMETHYLTRICARBALLYLIC ACID. 51

Terebie acid, C,H,,O,, melting at 174°, and oxalic acid are
formed by the oxidation of the above-mentioned liquid d-pinonic
acid with nitric acid of specific gravity 1.18. If, on the other
hand, liquid d-pinonic acid be oxidized by means of a chromie
acid mixture, the following acids’ result.

1. Isoketocamphoric acid, C,,H,,O,, melts at 128° to 129°. It
is a dibasic ketonic acid, identical with the acid prepared by
Thiel? in the oxidation of a-campholenic acid and described under
the name of isoxycamphoric acid, C,,H,,O,. It forms an owime,
melting at 185° to 186°, and a semicarbazone, melting at 187°.
It is decomposed by an alkaline hypobromite solution into isocam-
phoronic acid and carbon tetrabromide.

It is also prepared by the oxidation of a-dioxydihydrocampho-
lenic acid or of l-pinonic acid with chromic acid.’

2. Isocamphoronic acid,* C,H,,O,, melts at 166° to 167°. It
is a tribasic acid, and has been deseribed by Thiel? as an oxida-
tion product of a-campholenic acid. It is identical with oxy-
camphoronic acid, obtained, together with other products, by
Kachler® in the oxidation of camphor with nitric acid. Concen-
trated sulphuric acid converts it into terpenylic acid ° and carbon
monoxide; and acetyl chloride changes it into an anhydromono-
carboxylic acid, which, in turn, yields terpenylic acid by the
action of concentrated sulphuric acid, carbon monoxide being
eliminated.

This acid * may also be obtained from a-dioxydihydrocampho-
lenie acid or |-pinonic acid by the more vigorous oxidation with
chromic acid than is allowed when isoketocamphoric acid is re-
quired.

3. Terebic acid, C,H,,O,, melts at 174°.

According to Tiemann and Semmler,' if liquid d-pinonic acid
be dissolved in soda, and heated with an excess of a four per
cent. solution of potassium permanganate on the water-bath, the
following acids are formed.

1, Dimethyltricarballylic acid, C,H,,O,, melts at 147°. This
acid is obtained by extracting the oxidation products with
chloroform, from which solvent the crystals of this acid are de-
posited.

When heated above its melting point, it loses water, and yields

1Tiemann and Semmler, Ber., 28, 1344.

2W. Thiel, Ber., 26, 922.

3¥, Tiemann, Ber., 29, 3006.

4W. H. Perkin, jun., and Thorpe, Journ. Chem. Soc., 75 (1899), 1897.
5Kachler, Ann. Chem., 191, 143.

SF. Tiemann, Ber., 29, 2612.

52 THE TERPENES.

anhydrodimethyltricarballylic acid, which melts at 142.5°, and
boils at 225° under 16 mm. pressure.

2. Oxytrimethylsuccinic acid, C,H,,O,, melts at 141°. This
acid is obtained from the filtrate from the dimethyltricarballylic
acid. It has also been found by Kachler in the oxidation prod-
ucts of camphor. When treated with hydriodic acid, it is con-
verted into trimethylsuccinic acid, melting at 145°.

3. An acid, which accompanies the above-mentioned acid, and
which was not isolated in a condition of purity ; when distilled
in a vacuum, this acid loses water, and, apparently, carbon diox-
ide, forming isocamphoranic acid, C,H,,O,. The latter is a lac-
tonic acid, and melts at 143.5°.

Oxyisocamphoronic acid, C,H,,O,, is a tribasic acid, and is pro-
duced by heating isocamphoranic acid with potassium hydroxide ;
it had previously been prepared in an impure condition by Kachler"
from camphor.

Isocamphoranic acid is perhaps isomeric with isocamphorenic
acid, melting at 226°, which Kachler obtained from isocampho-
ronic acid,

By the careful investigation of the above oxidation products
obtained from pinene, Tiemann and Semmler? claim to have
established the following constitutional formula for this terpene,

a
H—CH,
crf,

A,

CHs
So H
f

If crude pinene be oxidized with potassium permanganate, the
keto-lactone, C,,H,,O,, melting at 63° to 64°, is formed from an
impurity contained in commercial pinene. Tiemann and Semm-
ler* have designated this compound as methyl-3!-ethyl-3-hepta-
non-6-olide-1-3'. Wallach first described it as a product of the
oxidation of terpineol.

As a result of his researches on the oxidation products of
pinene, Baeyer* came to quite different conclusions regarding the

1Kachler, Ann. Chem., 191, 152.

*Tiemann and Semmler, Ber., 29, 3027.

STiemann and Semmler, Ber., 28, 1778.

*A. von Baeyer, Ber., 29, 3, 326, 1907, 1923 and 2775.

ON a a a ek a

BROMOTETRAHYDROCUMIC ACID. 53

constitution of pinene than Tiemann and Semmler; his results
seem to support Wagner’s formula of pinene. Some of the prod-
ucts which Baeyer prepared during these investigations are as fol-
lows.

1. a-Pinonic acid, C,,H,,O,. This acid is readily obtained by the
oxidation of pinene at 30° with potassium permanganate, accord-
ing to the method of Tiemann and Semmler. It melts at 103°
to 105°, and boils at 180° to 187° under 14 mm. pressure. It
constitutes the chief product of the oxidation, and may be readily
separated from the liquid products, owing to the fact that it is in-
soluble in ethyl nitrite. It is difficultly soluble in cold water and
ether, readily soluble in hot water and chloroform. On heating
with sulphuric acid it is converted into the keto-lactone, C,,H,,O,
(m. p. 63° to 65°). This solid @-pinonic acid is a ketonic acid,
and yields an a-oxime, which crystallizes in large plates or prisms,
and melts at 150°. The acid is optically inactive, and is to be
regarded as identical with Tiemann and Semmler’s i-pinonic acid.

When the syrupy mother-liquor, from which a-pinonic acid is
separated, is treated with hydroxylamine, it yields two oximes,
isomeric with the a-oxime, which Baeyer designates as f-owxime
and 7-oxime. The f-oxime melts at 128° and is identical with the
oxime melting at 125°, which Tiemann and Semmler obtained
from their liquid d-pinonic acid; it is dextrorotatory, [a], = +
2° 18’ (8.2 per cent. solution in ether in a one decimeter tube).
The 7-owime is less readily soluble than the £-oxime, and separates
from glacial acetic acid as a powder; it melts at 190° to 191°,
and is levorotatory.

The phenylhydrazone of a-pinonic acid melts with decomposition
below 100°.

a-Pinonic acid is oxidized by alkaline hypobromite, yielding
pinic acid, C,H,,O,, and bromoform, while dilute nitric acid oxi-
dizes it to pinic, oxalic and terebic acids.

2. Nopic acid, C,,H,,O,. This is a product of the oxidation of
commercial pinene or French turpentine oil with permanganate.
It is isomeric with a-pinonic acid, but it is not a ketonic acid.
It is sparingly soluble in water, but crystallizes from it in long
needles, melting at 126° to128°. Itforms crystalline salts with
the metals. It is an oxy-monobasic acid.

Bromotetrahydrocumic acid, C,,H,,BrO,, is formed by the action
of a glacial acetic acid solution of hydrogen bromide on nopic
acid. It is readily soluble in chloroform, sparingly in ether, and
insoluble in petroleum ; it crystallizes in leaflets, melting and de-
composing at 175°. It decolorizes a solution of permanganate,
and is an unsaturated compound.

54 THE TERPENES.

Dihydrocumic acid, C,,H,,O,, is formed by the action of hot,
twenty-five per cent. sulphuric acid or alcoholie potash on the
preceding compound. It is sparingly soluble in water, erystal-
Jizes from alcohol, melts at 130° to133°, sublimes at about 100°,
and boils at 176° under 14 mm. pressure. It reduces a cold alka-
line solution of permanganate, and is oxidized by potassium ferri-
cyanide to cumic acid, C,,H,,O,,.

Nopinone, C,H,,O, is a ketone which is produced by passing
steam through water in which lead peroxide and nopic acid are
suspended. It is a volatile oil, having a pleasant odor. Its
oxime is an oil, and its semicarbazone separates from methyl al-
cohol in needles, which melt at 188.5°. With benzaldehyde it
forms a condensation-product, benzylidene nopinone.*

According to Wallach,’ nopinone is also formed, together with
a-pinonic acid, during the oxidation of turpentine oil with potas-
sium permanganate. It originates probably from nopic acid,
C,,H,,O,, which, in addition to pinonic acid, is produced by the
oxidation of crude pinene, and which by continued oxidation is
decomposed into nopinone and carbon dioxide according to the
equation,

C,oH,,0; + O= C,H,,0 + CO, + H,0.

Homoterpenylic acid is formed by the oxidation of nopinone °
with fuming nitric acid.

3. Pinoylformic acid, C,,H,,O,, is a dibasic ketonic acid, which is
formed, together with a-pinonic acid, by the oxidation of pinene
under certain conditions. It is separated from the a-pinonic acid
by adding potassium carbonate in quantity insufficient to neutra-
lize the latter acid, which is then removed by ether; the solu-
tion of potassium pinoylformate is acidified, the free acid is taken
up in ether and, after evaporation of the ether, the resulting
oil is treated with potassium acid sulphite; the resulting com-
pound is then decomposed by a concentrated solution of barium
hydroxide, and free pinoylformic acid is obtained. It is readily
soluble in cold water and melts at 78° to 80°. Its silver salt
crystallizes in leaflets. The potassiwm- and sodium-hydrogen sul-
phite compounds are crystalline ; the phenylhydrazone crystallizes
in prisms, and melts with decomposition at 192.5°. Oxidation
converts pinoylformic acid into pinic acid, while fuming nitric
acid changes it into oxalic and terpenylic acids.

Homoterpenoylformic acid, C,,H,,O,, is a lactonic acid, which is

formed by treating pinoylformic acid with hot, dilute sulphuric

1Wallach, Nachr. k. Ges. Wiss., Goettingen, 1899, No. 2.
Wallach and Schiifer, Ann. Chem., 313, 363.

ape

a Cen OSA EAE a yy om

PINARIN. 55

acid. It is difficultly soluble in cold water and ether, crystallizes
in prisms, and melts at 126° to 129°. Its formation from pinoyl-
formic acid is analogous to the conversion of a-pinonic acid into
methyl-ethyl-heptanonolide (m. p. 63° to 65°). It yields an
oxime, which crystallizes in needles, and melts at about 170°.

Homoterpenylic acid, C,H,,O,, is produced by the action of lead
peroxide or fuming nitric acid on homoterpenoylformic acid. It
is sparingly soluble in water, but crystallizes from it in large
prisms, melting at 98° to 101° ; it separates from ether in crys-
tals, melting at 100° to 102.5°. It is a lactonic acid, and stands
in the same relation to adipic acid that terebic acid does to suc-
cinic acid.

Oxyhomopinic acid, C,,H,.O,, is an oxydibasic acid, which is
formed by the reduction of an alkaline solution of pinoylformic
acid with sodium amalgam. It crystallizes from water, and melts
at 130° to 133°. 7

a-Ketoisocamphoronic acid (dimethyltricarballoylformic acid),
C,H,,0,, is a keto-tribasic acid, which is obtained by the action
of sodium hypochlorite or hypobromite on pinoylformic acid. It
crystallizes from water in plates and leaflets, and melts with evo-
lution of gas at 186° to 187°. On heating its aqueous solution
with lead peroxide, it yields dimethyltricarballylic acid; the
anhydro-acid melts at 145° to 146°, and on boiling with water
gives dimethyltricarballylic acid, melting at 149° to 151°, while
by heating with water at 230° it gives the same acid, melting at
156° to 157°.

The lactone of a-oxyisocamphoronic acid, C,H,,O,, is formed by
reducing a-ketoisocamphoronic acid with sodium amalgam. It
crystallizes from water in prisms containing one molecule of
water, sinters at 160°, again solidifies, and finally melts at 185°
to 186°. When it is heated with hydriodic acid at 170° for four
hours, it yields isocamphoronic acid, C,H, ,O,.

The lactone of a-oxydimethyltricarballylic acid, C,H,,O,, is pre-
pared by the action of phosphorus tribromide and bromine on
dimethyltricarballylic acid and the treatment of the product with
boiling water. It is deposited in large crystals from ethy] acetate ,
it melts at 196° on slow heating, and at 207° by rapid heating.
It forms crystalline salts with certain metals. Fusion with ~
potash converts it into oxalic acid and as-dimethylsuccinic
acids.

4, Pinarin, C,,H,,O,, is deposited in crystals from the fraction
of the neutral oxidation product of pinene, boiling at 150° to 180°
at 15 mm. pressure. It separates from petroleum in needles,
melts at 66° to 68°, and exhibits certain properties of a lactone.

56 THE TERPENES.

._ 5. Pinie acid, C,H,,O,, is produced, together with bromoform,
by the action of alkaline hypobromite solution on a-pinonic acid ;
the yield is quantitative. It is a dibasic acid. It crystallizes in
splendid prisms, melting at 101° to 102.5°, does not form an
anhydride when treated with acetyl chloride, and is stable
towards a cold solution of permanganate and towards hydrobromic
acid ; at 100° its solution is slowly oxidized by potassium per-
manganate.

Bromopinic acid, C,H,,BrO,, is prepared by the action of phos-
phorus tribromide and bromine on pinic acid ; the product is then
treated with boiling water and extracted with ether, yielding an
oil from which crystals are slowly deposited.

Oxypinic acid, C,H,,O,, is obtained from the preceding com-
pound, either by the action of barium hydroxide, or by treating
bromopinic acid with silver acetate and hydrolyzing the result-
ant acetyl compound. This separates from water in. prisms, melt-
ing at 193° to 194°.

Norpic acid aldehyde, C,H,,O,, is formed by the oxidation of
oxypinic acid in a hot, dilute acetic acid solution with lead per-
oxide. It isan oil, and is soluble in water. Its semicarbazone
melts at 188° to 189°.

Norpic acid, C,H,,O,, is obtained by the oxidation of norpic
acid aldehyde. It crystallizes from ether in large crystals, melts
at 173° to 175°, and sublimes at about 100° in needles. It does
not yield an anhydride by the action of boiling acetyl chloride,
and is very stable towards oxidizing agents. It is a dibasic acid,
and forms a crystalline silver salt. Norpic acid is probably iden-
tical with the acid, C,H,,O,, which Wagner’ obtained by the
action of alkaline hypobromite on pinononic acid, C,H,,O,.

Baeyer regards pinic acid and norpic acid as derivatives of a
dimethyltetramethylene ring,

/ Os

co“CH,

—HCY /CH—
CH,

which he calls the “ picean-ring.” ?

2. CAMPHENE.

Since camphene is the only well known solid hydrocarbon of
the terpene series, its recognition in ethereal oils might be ex-
pected to be especially easy ; there is, however, only one ethereal

1G. Wagner and Ertschikowsky, Ber., 29, 881.
*Baeyer, Ber., 29, 2775.

>. aes et

CAMPHENE. 57

oil known from which a solid hydrocarbon, C,,H,,, melting at
about 30° and boiling at 162°, can be separated. This oil is ob-
tained from Pinus sibirica, and from it Goluboff! isolated a solid
hydrocarbon, which, according to Bertram and Walbaum,” may be
considered an impure camphene. It was therefore believed until
about the year 1894 that camphene did not occur free in nature.
The transformation of camphene into isoborneol, which was ac-
complished by Bertram and Walbaum by the action of glacial
acetic acid and sulphuric acid on this hydrocarbon, constitutes a
method by means of which the presence of camphene in mixtures
can be determined. The presence of camphene has thus been de-
tected by these chemists in citronella oil, camphor oil, lemon oil,
ginger oil, and oil of valerian (Japanese). According to Bouchar-
dat,’ camphene occurs in small quantity in oil of spike. Rose-
mary oil* contains inactive camphene. Schimmel & Co.’ have
also reported camphene present in Dalmatian and Italian oils of
rosemary, hemlock oil, and American turpentine oil. In all prob-
ability camphene occurs together with pinene in many other oils.
Camphene is artificially prepared by the action of concentrated
sulphuric acid upon pinene (Armstrong and Tilden ®) ; by heating
pinene hydrobromide or hydrochloride with sodium acetate and
glacial acetic acid at 200°, or by heating with other reagents
capable of withdrawing the elements of the halogen acids (Wal-
lach’) ; by heating pinene hydriodide with potassium phenolate at
160° to 170°, a very pure camphene is obtained (Wagner *), and
it may also be made in the same manner from pinene hydrochlo-
ride (Reychler*). It is also formed from borneol by heating with
acid potassium sulphate at 200° (Wallach”’), or by heating borneol
with dilute sulphuric acid (two parts of water and one part con-
centrated acid) at 60° to 100° for six to eight hours ; by the lat-
ter method the yield is said to be 90 per cent. of the theoretical
(Konowaloff"). It results also by heating isoborneol (300 grams)
with benzene (150 grams) and zinc chloride (200 grams), or by
boiling isoborneol with dilute sulphuric acid in a flask provided

1Goluboff, Chem. Centr., 1888, 1622.

*Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 15.

8G. Bouchardat, Compt. rend., 117, 1094.

4Gildemeister and Stephan, Arch. Pharm., 235 (1897), 582.
5Semi-annual report of Schimmel & Co., for October, 1897.
6Armstrong and Tilden, Ber., 12, 1753.

TWallach, Ann. Chem., 239, 6.

8Wagner and Brykner, Ber., 33, 2121.

9A. Reychler, Ber., 29, 695.

1Wallach, Ann. Chem., 230, 239.

4M, I. Konowaloff, Journ. Russ. Phys. Chem. Soc., 32 (1900), 76.

58 THE TERPENES.

with a reflux condenser (Bertram and Walbaum'). Camphene is
_also formed, together with “terpilene” (terpinene), isoborneol
(*levo-camphenol”), and “isocamphol” (fenchyl alcohol), by
heating French turpentine oil with benzoic acid at 150° (Bouch-
ardat and Lafont’). 2

According to Wallach and Griepenkerl,’ bornylamine, the base
corresponding to borneol, can also be converted into camphene, if
the free amine or its formyl derivative is heated with acetic an-
hydride at 200° to 210°:

C,)H,,NH, = CyoHyg + NH,.

In order to prepare camphene, it is most convenient to start
with borneol, from which borny] chloride is first obtained. This
compound yields camphene by heating with an excess of water
to which potassium hydroxide or magnesia has been .added
(Kachler*).

According to Wallach,’ dry bornyl chloride is gently warmed
with an equal weight of aniline. At first the chloride dissolves
to a clear solution. The mixture is then heated to the boiling
point of aniline, when the reaction, accompanied by an ebullition
of the liquid and separation of aniline hydrochloride, occurs sud-
denly, and is complete after a short time. The reaction-product
is then neutralized with hydrochloric acid and distilled with
steam ; camphene quickly passes over as a colorless liquid, which
at once solidifies to a crystalline mass, resembling paraffin. The
camphene which passes over toward the end of the distillation is
collected separately, since it contains impurities due to some
undecomposed chloride. The resulting camphene is pressed on
a porous plate, and after drying the melted hydrocarbon with
potassium hydroxide, it is rectified.

PROPERTIES.—Camphene is a solid hydrocarbon, melting at
48° to 49° and boiling at 160° to 161° ( Wallach’).

According to Briihl, camphene prepared from pinene melts at.
51° to 52°, solidifies at 50°, and boils at 158.5° to 159.5° ; the
same investigator finds camphene, obtained from bornyl chloride,
to melt at 53.4° to 54°, and to solidify at 53° to 52.5°.

It crystallizes from alcohol, in which it is comparatively diffi-
cultly soluble. It exists in an optically inactive, a levo- and a

‘Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 8.
*Bouchardat and Lafont, Compt. rend., 113, 551.
S’Wallach and Griepenkerl, Ann. Chem., 269, 349.
‘Kachler, Ann. Chem., 197, 96.

5Wallach, Ann. Chem., 230, 233; Ber., 25, 916.
Wallach, Ann. Chem., 230, 234.

4 De pink ny —

CAMPHENE. 59

dextrorotatory modification. These three varieties of this hydro-
carbon, which are analogous to those of pinene, agree completely
in all other physical and chemical properties. The specific gravity
of melted camphene is:

According to Wallach,’ 0.850 at 48°.

According to Briihl,? 0.84224 at 54°.

According to Briihl,’ 0.83449 at 63.7°.

The coefficients of refraction are :

n, = 1.4555 at 48° (Wallach and Pulfrich’).
Ny, = 1.4514 at 54° (Brihl ’).
Dy, = 1.45085 at 63.7° (Brihl*).

From this, a value for the molecular refraction is found which
agrees with the calculated value, if we consider camphene to pos-
sess one double linkage.

The molecular heat of combustion of camphene derived from
pinene has been determined by Stohmann?* to be 1466.7 calori-
metric units, while that of camphene obtained from borneol is
1470.3 calories.

Levo-camphene, prepared from pinene hydrochloride by the
action of an alcoholic solution of potassium acetate, has the spe-
cific rotatory power, [a], = — 80° 37’ (Bouchardat and Lafont *).

Camphene is not stable at a high temperature. By continued
heating at 250° to 270°, it is converted into a liquid consisting
of unchanged camphene and products of higher and lower boil-
ing points. Dehydrating agents also decompose camphene ; thus
phosphoric anhydride converts it into an oil apparently containing
cymene, and partially into resin; a similar reaction takes place
when camphene is heated with zinc chloride at 200°. Concen-
trated sulphuric acid acts very energetically on camphene,’ while
in contrast to pinene, dilute sulphuric acid acts slowly upon it.°

According to Marsh and Gardner,’ phosphorus pentachloride
converts camphene into a reaction-product, which, when treated
with water, is resolved into two crystalline acids, a-camphene-
phosphorous acid, (C,,H,,PO,H,),+H,O, and $-camphene-phos-
phorous acid, C,,H,,PO,H,; the salts of the latter decompose
readily on heating into meta-phosphoric acid and camphene.

1Wallach, Ann. Chem., 245, 210; 252, 136.
2Briihl, Ber., 25, 160.

3Compare Briihl, Ber., 25, 170.

4Bouchardat and Lafont, Compt. rend., 104, 693.
5Wallach, Ann. Chem., 230, 234.

6Wallach, Ann. Chem., 239, 9.

TMarsh and Gardner, Journ. Chem. Soc., 1894, 35.

60 THE TERPENES.

When camphene is heated with glacial acetic and sulphuric
acids, the acetyl derivative of isoborneol is formed (Bertram and
Walbaum'). This reaction also demonstrates that the camphene
molecule is more stable than that of pinene, since the latter hy-
drocarbon is converted by an analogous reaction, first into dipen-
tene and then into terpineol.

The action of trichloracetic acid on camphene? converts the
latter into an ester of isoborneol, which, on saponification, yields
isoborneol.

A compound of camphene with nitrosyl chloride has not been
obtained.’

The action of nitrous acid on camphene has been investigated
by Jagelki;* he obtained the following compounds. ‘

1. Camphene nitronitrosite, C,,H,,-N,O,.—This compound sep-
arates as a white, crystalline powder, when a well cooled mixture
of a solution of camphene in ligroine and a concentrated solution
of sodium nitrite is treated very slowly with acetic acid. Its
color changes to a blue when it is heated, and it decomposes at
about 149°, with elimination of water and oxides of nitrogen. It
is insoluble in the ordinary solvents, but dissolves in hot nitro-
benzene, forming a blue colored solution.

2. Camphene nitrosite, C,,H,,.N,O,—The ligroine solution,
freed from the preceding compound by filtration, is agitated with
a concentrated solution of potassium hydroxide, which removes the
nitrosite in the form of its potassium salt ; when the latter is de-
composed with acids it yields the free nitrosite. It is a greenish
oil, having a pleasant odor, which decomposes readily at 50°
when heated under reduced pressure, yielding nitrous oxide, water,
and camphenilic nitrite. - Its potassiwm salt separates in red crys-
tals from alcohol, which detonate on heating; the benzoyl deriva-
tive is an oil, which decomposes on distillation.

3. Camphenilic nitrite, C,,H,,NO,\This substance is obtained
from the ligroine solution, which has been freed from the nitro-
nitrosite and nitrosite as above described, by the evaporation of
the ligroine. It crystallizes from petroleum in needles, melts at
66°, boils at 147° under a pressure of 12 mm., and detonates on
heating strongly. It gives a cherry-red coloration on warming
with concentrated sulphuric acid. It is converted into cam-
phenilan aldehyde, C,,H,,O, by the reduction with tin and hydro-
chloric acid or with zinc dust and acetic acid; this aldehyde is

1Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 1.
2A. Reychler, Ber., 29, 695.

3Wallach, Ann. Chem., 245, 255.

4W. Jagelki, Ber., 32, 1498.

Low Ae
ro

Ne

Sat ae sake

CAMPHENE HYDRIODIDE. 61

also obtained by Bredt and Jagelki* in the oxidation of camphene
with chromyl chloride. Oxidation with potassium permanganate
or treatment with alcoholic potash converts camphenilic nitrite
into camphenilone® (camphenylone), C,H,,0. Camphenilic nitrite
is also one of the products which are formed during the oxidation
of camphene with nitric acid, although in this case its produc-
tion depends on the initial formation of camphene nitrosite, formed
by the addition of the elements of nitrous acid to camphene,
which then loses water and nitrous oxide, and yields camphenilic
nitrite.

Camphene hydrochloride, C,,H,,-HCl.—According to Reychler,’
this addition-product is formed when hydrogen chloride is led
into an alcoholic solution of camphene, and isobornyl chloride is
produced by a similar treatment of isoborneol. Reychler‘* gives
the melting point of camphene hydrochloride, crystallized from
alcohol containing hydrogen chloride, at 149° to 151°, and that
of isobornyl chloride at 150° to 152° ; he regards these two com-
pounds as identical, and stereoisomeric with borny] chloride.

According to Jiinger and Klages,” camphene hydrochloride
melts at 165°, but after standing for four hours it melts at 158°;
after crystallization from alcohol containing hydrogen chloride, it
melts at 152°. When treated with glacial acetic acid, it yields
isobornyl acetate from which isoborneol is obtained by hydrolysis.
When reduced with sodium and alcohol, the hydrochloride loses
hydrogen chloride and yields a mixture of camphene and dihydro-
camphene identical with that from pinene hydrochloride.®

Camphene hydrobromide,’ C,,H,,- HBr, separates from alcohol in
well formed crystals and melts at 133°. It is reconverted into
camphene by alcoholic alkalis and also by reduction with sodium
and alcohol.

Camphene hydriodide,’ C,,H,,-HI, forms colorless crystals, melt-
ing at 48° to 55°; when it is treated with alcoholic potash, it
gives camphene, melting at 49°, together with some unaltered
iodide. It reacts with silver oxide, yielding camphene and
borneol (?). ORL,

By the action of phosphorus trichloride and bromine on cam-
phor, Marsh and Gardner ® obtained a- and f-tribromocamphene

iBredt and Jagelki, Ann. Chem., 310, 112.

2Balaise and Blanc, Compt. rend., 129 (1899), 886.
3A. Reychler, Ber., 29, 697.

4A, Reychler, Bull. Soc. Chim., 1896 (III.), 15, 366.
5Jiinger and Klages, Ber., 29, 544.

6Semmler, Ber., 33, 3420. .

TKondakoff and Lutschinin, Chem. Zeit., 25, 131.
8Marsh and Gardner, Journ. Chem. Soc., 71, 285.

62 THE TERPENES.

hydrobromide, C,,H,,Br,, melting at 168°, and 143° to 144°, re-
spectively ; both compounds yield tribromocamphene, C,,H,,Br,,
melting at 75° to 76°, when treated with sodium methylate. The
action of phosphorus pentachloride on camphor yields a-chloro-
camphene hydrochloride, C,,H,,Cl,, melting at 165°, and the latter
is converted into a-chlorocamphene, C,,H,,Cl, by the action of zine
dust and glacial acetic acid. By the action of sulphuric acid con-
taining five per cent. of water, z-chlorocamphene is converted into
a compound, C,,H,,O, which was at first called ‘“ oxycamphene”
or “camphenol”'; this oxygen-containing compound was sub-
sequently investigated by Marsh and Hartridge, who changed its
name to carvenol, C,,H,,O; it is quite probable that this com-
pound is identical with the ketone, C,,H,,O, previously described
by Wallach’ under the name of carvenone.

a-Dichlorocamphene, C,,H,,Cl,, is a derivative of camphor, which
was prepared by Lapworth and Kipping® by heating a-chlorocam-
phenesulphonic chloride; it crystallizes from methyl alcohol in
prisms or needles, melts at 72° to 73°, sublimes readily, and is
volatile with steam.

Monobromocamphene, C,,H,,Br.—According to Wallach,‘ a solu-
tion of camphene in four parts of alcohol and four parts of ether
removes the color of two atoms of bromine, the reaction proceed-
ing with less vigor than in the bromination of pinene ; when the
reaction-product is distilled with steam, an oily liquid is obtained,
which contains only one atom of bromine. On reduction with
sodium and alcohol, it yields camphene.°

A bromocamphene, prepared by treating camphene hydro-
chloride (m. p. 165°) with bromine and distilling the reaction-
product with quinoline, is described by Jiinger and Klages® as an
oil, boiling at 226° to 227°; it has the specific gravity 1.265 at
15°, the index of refraction, np, = 1.52605 at 15°, and the
molecular refraction, M = 52.36.

Camphene dibromide, C,,H,,Br,.— According to Reychler,’ when
camphene is brominated according to Wallach’s method and the
monobromocamphene, C,,H,,Br, is removed by distillation with
steam, a compound, non-volatile with steam, remains in the dis-
tilling flask; it crystallizes from alcohol in colorless prisms,

1Marsh and Hartridge, Journ. Chem. Soc., 78, 852.

Wallach, Ann. Chem., 277, 122. :
lest and Kipping, Journ. Chem. Soc., 69, 1559; see also, 69, 1546;

4Wallach, Ann. Chem., 230, 235.

5Semmler, Ber., 33, 3420.

SJiinger and Klages, Ber., 29, 544.

TA. Reychler, Ber., 29, 900.

ANHYDROCAMPHOIC ACID. 63

melts at 90°, and has the composition, C,,H,,Br,. It is likewise
formed by slowly adding bromine to a solution of camphene in
light petroleum, cooled to — 10°.

According to Semmler,' camphene dibromide is probably formed
by the addition of hydrogen bromide to the bromocamphene which
is the primary product of the action; it may be reconverted into
bromocamphene by distilling with quinoline. It is not readily
acted on by alcoholic potash, but is reduced by sodium and
aleohol to a dihydrocamphene identical with that from pinene
hydrochloride.

Oxidation of Camphene.

A chromic acid mixture converts camphene into camphor, oxy-
eamphor, C,,H,,O,, carbonic acid, acetic acid and camphoric acid
(Kachler and Spitzer’). (According to more recent investigations
by Semmler,' it is stated that camphene is never oxidized to cam-
phoric acid.)

According to Wagner,’ the oxidation of camphene with a dilute
solution of potassium permanganate in the cold yields camphene
glycol, C,,H,(OH),, melting at 192°, and camphenilic acid,
C,,H,,O,, melting at 170° to 172°.

By the oxidation of camphene with dilute nitric acid, Marsh
and Gardner * obtained the following acids.

1. Camphoic acid (camphoylic or carboxyl-apocamphoric acid),
C,,H,,0,.—This tribasie acid is prepared by heating camphene
with nitric acid of specific gravity 1.3 on the water-bath; the
crud eacid is purified by recrystallization from hot nitric acid, sp.
gr. 1.42. When crystallized from nitric acid or water, it melts
with decomposition at 196° ; crystallized from ether, it melts at
197° to 198° ; but when a pure specimen is prepared from anhy-
drocamphoic acid, it melts and decomposes at 199° to 200°.

It is also produced by the oxidation of chlorocamphene phos-
phorie acid, C,,H,,Cl-PO,H, (prepared by the action of phos-
phorus pentachloride on camphene and subsequent treatment of
the product with water), by means of nitric acid. On distillation
it loses water and carbon dioxide, and yields camphopyric anhy-
dride, C,H,,O,, and isocamphopyric acid, C,H,,O, (m. p. 209°).

Anhydrocamphoic acid, C,,H,,O,, is formed by the action of
acetyl chloride on camphoic acid; it crystallizes from ether in
large, transparent plates, melting at 205°.

1Semmler, Ber., 33, 3420.

*Kachler and Spitzer, Ann. Chem., 200, 341.

3G. Wagner, Ber., 23, 2311.

4Marsh and Gardner, Journ. Chem. Soc., 1891 (1), 648; 1896 (1), 74.

64 THE TERPENES.

Other derivatives of camphoic acid are cis-, meso- and trans-
camphopyric acids,' C,H,,O, melting at 203° to 204°, 160° to
170°, and 190° to 191°, respectively ; and cis-camphopyric anhy-
dride, C,H,,O,, melting at 178°.

2. Terephthalic acid, camphoric acid, CipH,,O, and succinic acid.

In addition to camphoic acid, Jagelki* obtained the following
compounds by the oxidation of camphene with dilute nitric acid.

1, Anhydrocamphenilic acid, C,,H,,O,, crystallizes in plates and
melts at 147.5° to 148°. Since it is indifferent towards potas-
sium permanganate, Wagner® regards it as a derivative of a class
of compounds which he terms ¢tricyclenes.

2. Camphenilone, C,H,,O, is a ketone, melting at 36° to 38° and
boiling at 195° under 738 mm. pressure.* It is also formed by
the oxidation of camphenilic acid, C,,H,,O,, with lead peroxide.
Its oxime melts at 105° to 106°, and the semicarbazone melts and
decomposes at 220° to 222°. ’Camphenilone is readily reduced
to an alcohol, C,H,,OH, which, in turn, may be converted into a
chloride, C, H. Cl; ‘when the latter is heated with aniline, it yields
an unsaturated hydrocarbon, camphenilene, C,H,,, boiling at 142°.

When camphenilone oxime is heated with dilute sulphuric acid,
it loses water and is converted into the nitrile of an unsaturated
acid, C,H,,N ; by hydrolysis, this yields the unsaturated campho-
ceenic acid, C HO, melting at 54°. If this acid be oxidized
with a cold, dilute solution of potassium permanganate, it gives
rise to dioxycamphoceanic acid, C,H,,O,, melting at 163° ; on dis-
tillation in vacuum this dioxy-acid is converted into a mixture of
a ketonie acid, camphoceonic acid, C,H,,O,, melting at 173°, and
the lactone of oxycamphoceonic acid, C,H,,O,, melting at 58°.
When dioxycamphoceanic acid is oxidized with dilute nitric
acid, it yields dimethyltricarballylic acid, C,H,,O,, melting at 157°
to 158°, which, on fusion with potash, gives rise to oxalic acid
and as-dimethylsuccinic acid, C,H,,O,.

3. Camphenilic nitrite, C, H, NO, (see above).

By the action of nitric anhydride on a solution of camphene in
chloroform, an acid,® C,,H,,O,N, is formed, which crystallizes
from dilute alcohol in prisms, melting at 140° to 141° and de-
composing at 165° to 170°. It forms a soluble potassium salt,

‘For complete synthesis of camphopyrie (apocamphoric) acid, page
Komppa, Ber., 34, 2472.

2W. Jagelki, Ber., 32, 1498; compare Bredt and Jagelki, Chem. Zeit., 20
(1896), 842.

SMajewski and G. Wagner, Journ. Russ. Chem. Soc., 29 onic 124;
Chem. Centr., 1897 (I.), 1056.

+Blaise and Blanc, Compt. rend., 129 (1899), 886.
5Demjanoff, Journ. Russ. Phys. ‘Chem. Soe., 33, 283.

CAMPHENE ALCOHOLATE. 65

and_a sparingly soluble silver salt. On reduction with tin and
hydrochloric acid, or on heating with concentrated potash, the acid
is converted into anhydrocamphenilic acid, C,,H,,O, (m. p. 148°).

The compound,’ C,,H,,-2CrO,Cl,, is formed when a solution of
eamphene in carbon bisulphide is treated with chromy] dichloride.
It is a pale brown powder, very hygroscopic, and is somewhat
soluble in ether.

Camphenilan aldehyde, C,,H,,O, is obtained by the treatment of
the preceding double compound with water. It melts at about
70°, and boils at 96° under 14 mm. pressure. It is identical
with camphene aldehyde, C,,H,,O, previously prepared by Etard,
and also by Wagner from camphene glycol and hydrochloric acid.
* Camphenilanic acid, C,,H,,O,, results by the oxidation of cam-
phenilan aldehyde with a current of air; it melts at 65°. When
the aldehyde is oxidized by the usual oxidizing agents it yields
isocamphenilanie acid, C,,H,,O,, melting at 118° ; this acid is also
formed by heating camphenilanic acid with nitric or chromic acid.
When camphenilanic acid is treated with bromine and the result-
ant monobromo-derivative is boiled with alcoholic potash, it is
converted into oxycamphenilanic acid, C,,H,,O, ; this acid melts at
170° to 172°, and is identical with camphenilic acid, C,,H,,O,,
which Wagner obtained in the oxidation of camphene with potas-
sium permanganate.

Two isomeric nitrates, C,,H,,-HNO,, have been obtained by
Bouveault* by gradually adding a solution of camphene in chlo-
roform to cold fuming nitric acid. One of these nitrates decom-
poses when distilled under diminished pressure, and the other
boils at 110° under 10 mm. pressure, has a specific gravity
1.0988 at 0°, and is reverted into camphene by alcoholic potash.

Ethyleamphene, C,,H,,-C,H,, and isobutyleamphene, C,,H,,-C,-
H,, were prepared by Spitzer,’ and hydrazocamphene, C,,H,,NO,,
was obtained by Tanret.*

Camphene alcoholate,’ C,,H,,-OC,H,, is prepared by boiling a
mixture of camphene, alcohol, and sulphuric acid; it is an oil,
boils at about 200°, has a sp. gr. 0.895 and a refractive index,
Ny = 1.4589; it is identical with isoborneol ethyl] ether.

In addition to the above-mentioned derivatives of camphene, a
series of very interesting and important compounds has been ob-

iBredt and Jagelki, Ann. Chem., 310, 112.

2],, Bouveault, Bull. Soc. Chim., 23 (1900, ITI.), 535.

8Spitzer, Ann. Chem., 197, 133.

4Tanret, Compt. rend., 102, 791; 104, 917; 106, 660 and 749; Ber., 20,
253 and 285, Ref.; 21, 237. and 352, Ref.

5Semmler, Ber., 33, 3420.

aa:

66 THE TERPENES.

tained by Forster; for a description of the method of prepara-
tion, properties, etc., of these substances (bromonitrocamphane,
C,,H,,BrNO,, nitrocamphene, C,,H,,NO,, amidocamphene, C,,-
H,,NH,, hydroxycamphene, C,,H,,OH, etc.), reference must be
made to the original publications under the title, ‘‘ Studies in
the Camphane Series.” *

3. FENCHENE.

Although fenchene has not yet been found in nature, neverthe-
less it may form a constituent of many turpentine oils (compare
with fenchy] alcohol). .

The methods for the artificial preparation of this terpene are
limited to the reduction of fenchone, C,,H,,O, and elimination of
the elements of water from the resulting fenchy] alcohol, C,,H,,OH.
Fenchene is formed when fenchyl alcohol is heated with acid
potassium sulphate.

In order to prepare fenchene, it is most convenient to convert
fenchy] alcohol into fenchyl chloride. Equal weights of fenchyl
chloride and aniline are warmed in a flask connected with reflux
condenser, and the mixture is heated to the completion of the
somewhat violent reaction. The mass is then allowed to cool,
treated with an equal volume of glacial acetic acid, and the fen-
chene is distilled off with steam ; phenyl fenchylamine remains in
the residue in the distilling flask. The hydrocarbon is purified
by fractional distillation (Wallach ’).

PROPERTIES.—According to Wallach,? fenchene is a liquid
hydrocarbon, which boils at 155° to 156°, has a specific gravity of
0.867 and a refractive index equal to 1.4690 at 20° and 1.47047
at 18°; its odor resembles that of camphene. According to Gard-
ner and Cockburn,’ fenchene, prepared by Wallach’s method and
purified by careful fractionation, distills chiefly at 150° to 152°,
with small fractions from 152° to 160°; the fraction boiling at
150° to 154° has a specific gravity 0.8667 at 18°, and a specific
rotatory power, [a], = — 6.46° (not in solution).

In a more recent investigation, Wallach* finds that when levo-
rotatory fenchyl alcohol, prepared by the reduction of dextro-
rotatory fenchone, is treated with phosphorus pentachloride, it
gives rise to two fenchyl chlorides, and these, in turn, yield two
fenchenes, the one dextrorotatory, and the other levorotatory ;

1M. O. Forster, Journ. Chem. Soc., 77, 251; 79, 644, 653, 987 and 1003.

Wallach, Ann. Chem., 263, 149; 302, 376.

3Gardner and Cockburn, Journ. Chem. Soe., 73 (1898), 276; compare with
Bertram and Helle, Journ. pr. Chem., 61, 1900 (II.), 293.

‘Wallach, Ann. Chem., 302, 371; 315, 273.

FENCHENE. 67

since both fenchenes are derived from dextro-fenchone, Wallach
designates them as D-d-fenchene and D-/-fenchene, respectively.
The optical rotation of fenchyl chloride, obtained from D-1-fenchyl
alcohol, varies between the limits, [a], = — 13° and + 5.1°, in
a one decimeter tube ; the direct product, prepared at a relatively
low temperature, is always levorotatory, but the subsequent treat-
ment which it receives, especially repeated distillations, modifies its
rotatory power. When prepared by heating on the water-bath a
dextro-fenchyl chloride results. By the elimination of the ele-
ments of hydrogen chloride by means of aniline or quinoline
from strongly levorotatory fenchyl chloride, levo-fenchene is always
formed ; but feebly levorotatory, or nearly inactive, fenchy]
chloride yields a mixture of ]- and d-fenchene, which is optically
inactive or dextrorotatory. The limits of rotation for l- and
d-fenchene are, [a], = + 21°, in a one decimeter tube. Dextro-
fenchene is best prepared from fenchy] chloride which has not been
distilled. Levo-fenchene may be obtained by heating d-fenchene
with alcoholic sulphuric acid for several hours; the reverse trans-
formation does not appear to take place. 1-Fenchene may be
isolated from a mixture of the two modifications by fractional
oxidation with a three per cent. solution of potassium permanga-
nate ; by this treatment, D-d-fenchene is oxidized in a few minutes,
while D-l-fenchene is only slowly attacked, and may be removed
from the reaction-product by distillation with steam.

An optically inactive fenchene was obtained by Wallach? in
his first investigation of fenchene.

Levo-fenchyl chloride* is formed by saturating a solution of
either d- or |-fenchene in glacial acetic acid with hydrogen chlo-
ride, pouring the product into water, and distilling with steam.
When the resultant 1-fenchyl chloride is heated with aniline,
l-fenchene is obtained ; by this method, therefore, d-fenchene may
be converted into 1-fenchene.

L-d-Fenchy] alcohol, obtained from 1-fenchone, acts in a similar
manner to D-l-fenchyl alcohol, when it is converted into its’
chloride; the fenchene obtained from it yields L-d-oxyfenchenic
acid (m. p. 152° to 153°), when it is treated with alcoholic sul-
phuric acid and is subsequently oxidized with a permanganate so-
lution (see below).

1The capital letters designate the optical rotation of the original com-
peund, and the small letters that of the final product; thus, D-l-fenchene is
the levorotatory terpene obtained from dextrorotatory fenchone, and
D-1-fenchyl alcohol is the levorotatory alcohol derived from dextro-fenchone.

2Wallach, Ann. Chem., 263, 150.

3Wallach, Ann. Chem., 302, 382.

68 THE TERPENES.

According to Kondakoff,' the action of alcoholic potash on
fenchyl bromide, and to a less extent on the chloride, gives a
product which consists of two isomeric fenchenes ; one of these
has been isolated in a pure form. It boils at 140° to 141°, has
a sp. gr. 0.8385 at 20°, the rotatory power is [4] p = — 55°; it
shows the properties of a reduced aromatic compound with a
double linking in the ring.

Fenchene hydrochloride,’ C,,H,,. HCl, closely resembles fenchy]l
chloride, C,,H,,Cl, and is probably almost all tertiary ; moist
silver oxide converts it into isofenchy] alcohol.

Fenchene hydrobromide,” C,,H,,,HBr, resembles fenchyl bro-
mide; [a], = —27° 16’.

Fenchene hydriodide,? C,,H,,.HI, boils at 120° to 120.5°
(23 mm.), has asp. gr. 1.427 at 21°/4° and [a] ,= + 42°57’ at
40°; when treated with alcoholic potash, it yields a mixture of
fenchene (b. p. 143° to 150°, sp. gr. 0.8482 at 19°/4°), and
unaltered hydriodide ; the latter reacts with moist silver oxide,
yielding solid fenchy] alcohol.

Fenchene unites with two atoms of bromine forming an oily
dibromide, which, however, has not been obtained in a condition
of purity.

When fenchene is treated with a mixture of glacial acetic”and
sulphuric acids, it is converted into isofenchyl alcohol,* C,,H,,OH,
melting at 61.5° to 62°. This transformation is similar to that
of camphene into isoborneol.

Fenchene alcoholate,” C,,H,,OC,H,, is produced by heating
D-d-fenchene with alcoholic sulphuric acid ; it boils at 200° to
201°, and on treatment with sodium it yields the sodium deriy-
ative of the alcohol, C,,H,,OH. This alcohol melts at 61°, and
is identical with isofenchyl! alcohol.

Oxidation Products of Fenchene.

As is mentioned above, D-d- and D-I-fenchene react quite dif-
ferently toward potassium permanganate. Twenty grams of D-I-
fenchene require about twelve hours to be oxidized in the cold with
a three per cent. solution of permanganate, while under the same

1Kondakoff and Lutschinin, Journ. pr. Chem., 1900 (II.), 62, 1; Chem.
Zeit., 25, 131.

4Kondakoff, Journ. pr. Chem., 1900 (II.), 62, 1.

’Kondakoff, Chem. Zeit., 25, 131.

‘Bertram and Helle, Journ. pr. Chem., 61, 1900 (II.), 293.

5Wallach, Ann. Chem., 315, 273.

ee oa 9* A IGP ere ye ies

FENCHOCAMPHORONE. 69

conditions D-d-fenchene is completely oxidized in a few minutes.
The product is in each case an oxyfenchenic acid,' C,,H,,O,.

1. D-1-Oxyfenchenic acid,’ C,,H,,O,, is the oxidation product of
pure D-l-fenchene. It crystallizes from dilute acetone in leaflets,
and melts at 152° to 153°; like the hydrocarbon from which it
is derived, it is levorotatory, [a], = — 56.8°. The same acid
may also be obtained by the oxidation of D-1l-fenchy] chloride
with permanganate. Its acetyl derivative melts at 109° to
110°.

D-d-Fenchocamphorone,* C,H,,O, is formed by the oxidation of
D-l-oxyfenchenic acid in an acid solution. It melts at 109° to
110°, boils at 202°, and is dextrorotatory, [a] = +14.64°. It
is a ketone isomeric with phorone, has the odor of camphor, and
is very similar to it. Its owime, C,H,,NOH, melts at 69° to 71°,
is levorotatory, [a] p= — 50.30°, and yields fenchocamphoni-
trile,? C,H,,N, on treating with dilute sulphuric acid. On re-
ducing this nitrile with alcohol and sodium, a base, C,H,,-NH,, is
obtained, and is identified by means of its platinochloride and
earbamide. An isomeric fenchocamphylamine, C,H,,-NH., pro-
duced by the direct reduction of fenchocamphoronoxime with amyl
alcohol and sodium, boils at 196° to 199°, and solidifies at low
temperatures ; its hydrochloride, C,H,,-NH,-HCl, is very stable,
and crystallizes from a mixture of ether and alcohol.

Fenchocamphorone semicarbazone melts at 210° to 212°, and is
levorotatory, [¢] = — 131.38°.

Fenchocamphorone* is oxidized by nitric acid, sp. gr. 1.25,
yielding two acids, which melt at 124° and 202°, respectively ;
the acid melting at 202° has the formula, C,H,,O,, and yields
the anhydride, C,H,,O, (m. p. 176° to 177°), and a monanilide
(m. p. 211°). These compounds agree in their properties with
the corresponding derivatives of cis-cumphopyric acid,’ and hence
the two acids are identical (see page 64).

When fenchocamphorone is reduced by sodium and aqueous
ether, fenchocamphorol,’ C,H,,OH, is obtained ; it crystallizes from
dilute methyl alcohol in needles, melting at 128° to 130°. A
pinacone, C,,H,,O,, melting at 192° to 193°, is also formed dur-
ing the reduction.

1Wallach, Ann. Chem., 284, 333; 300, 313; 315, 273.

2Wallach, Ann. Chem., 302, 377.

sWallach, Ann. Chem. 300, 313; 302, 383; 315, 273; Chem. Centr., 1899
(IT.), 1052.

#Wallach, Ann. Chem., 300, 313; 315, 273.

5Marsh and Gardner, Journ. Chem. Soc., 69, 77.

6Wallach, Ann. Chem., 300, 313.

70 THE TERPENES.

2, D-d-Oxyfenchenic acid,’ C,,H,,O,, is the oxidation product of
pure D-d-fenchene. It crystallizes from dilute acetone in well
formed, transparent prisms, melting at 138° to 139°; it is dex-
trorotatory, [a],= + 7.696°. Other acids are simultaneously
formed with this compound, but they have not yet been obtained
pure. Its acetyl derivative crystallizes in prisms, and melts at
122° to 124°.

D-1-Fenchocamphorone,' C,H,,O, is produced by the oxidation
of D-d-oxyfenchenic acid ; it melts at 62° to 63°, boils at 201° to
202°, is very volatile with steam, and slightly soluble in water.
It is levorotatory, (a) p= —16.69°. Its oxime is very soluble
in all solvents, melts at 54° to 56°, and is dextrorotatory,
[2]>= + 49.03°; a nitrile is formed at once by heating the
oxime with mineral acids.

Its semicarbazone crystallizes from hot alcohol in prisms, melting
at 204° to 206°, and is dextrorotatory, [a], = + 58.11°.

D-l-Fenchocamphorone differs from its D-d-isomeride in not
yielding a camphopyric acid with dilute nitric acid. The prin-
cipal product of this action is an acid whose mono- and di-anilides
agree in properties with those of as-dimethylsuccinic acid ; but

there is a discrepancy in the melting points of their anhydrides, —

that from the acid derived from D-l-fenchocamphorone melts at
125° to 130°, whilst as-dimethylsuccinic anhydride melts at 29°
(Wallach’).

3. L-d-Oxyfenchenic acid,’ C,,H,,O,.—This compound is pre-
pared as follows. 1-Fenchone is reduced to L-d-fenchy] alcohol
({24],= + 10.36°), and the latter is converted into fenchy]l
chloride, and this, in turn, into fenchene; the hydrocarbon is
heated for several hours with alcoholic sulphuric acid, and then
the strongly dextrorotatory terpene is oxidized with permanganate.
The resulting L-d-oxyfenchenic acid melts at 152° to 153°, and
is dextrorotatory, [a], = + 57.29°.

The racemic oxyfenchenic acid,? C,,H,,O,, is prepared by crystal-
lizing from ether a mixture of equal quantities of D-l-oxyfenchenic
acid and L-d-oxyfenchenic acid ; it melts at 142° to 143°, lower
than either of its components.

The L-l-oxyfenchenic acid and the corresponding inactive,
racemic modification have not yet been prepared.

In general it may be stated that different specimens of crude
fenchene vary greatly in their behavior towards permanganate,
and usually yield a mixture of D-I- and D-d-oxyfenchenie acids,

Wallach, Ann. Chem., 302, 378 and 384.

2Wallach, Ann. Chem., 315, 273.
8’Wallach, Ann. Chem., 302, 378 and 379.

a SNe — ail pict

Pu

LIMONENE. 71

the levo-isomeride predominating. Some samples of fenchene
contain readily oxidizable compounds, and in such cases the prod-
uct of oxidation is a complex mixture consisting of the two oxy-
fenchenic acids, together with acids of the acetic series and a
ketonic acid,’ C,H,,O,; the latter gives a semicarbazone, melting
at 210°, and a silver salt. This ketonic acid may possibly be
formed from a third isomeric fenchene, which is contained in
crude fenchene.

Fenchene differs from other terpenes in being relatively stable
towards strong nitric acid in the cold, but it is vigorously at-
tacked by the hot acid. According to Gardner and Cockburn,”
when twenty grams of fenchene are heated on the water-bath with
100 cc. of water and 100 cc. of concentrated nitric acid, and the
product is distilled with steam, the following oxidation products
are obtained.

1. Acetic acid.

2. Cis-camphopyric acid, C,H,,O,, is obtained from the non-
volatile oil remaining in the distilling flask ; it melts at 207°.

3. Cis-camphopyric anhydride, C,H,,O,, melts at 178°.

4, An acid whose constitution is not yet determined.

4a, LIMONENE.

Limonene is the optically active modification of dipentene.
While pinene and camphene exist in the active and inactive
modifications, agreeing in all properties except in their action on
polarized light, limonene bears the same relation to dipentene as
the optically active tartaric acids to racemic acid. For this
reason, the name dipentene has been retained for inactive limo-
nene, and both modifications will be separately considered.

Limonene (designated in the early literature as hesperidene,
citrene, and carvene), is, next to pinene, the most widely distrib-
uted terpene occurring in nature. Dextrorotatory limonene® is
found in the following ethereal oils: oil of orange* and orange
peel,* lemon,‘ bergamot,‘ caraway,‘ dill,* erigeron,’ kuromoji,°
massoy bark,’ and celery. Levo-limonene occurs in the oil from

Wallach, Ann. Chem., 315, 273.

2Gardner and Cockburn, Journ. Chem. Soc., 73, 277.

8Gildemeister and Stephan, Arch. Pharm., 235 (1897), 582; see also J.
Flatan and Labbé, Bull. Soc. Chim., 19, 1898 (III.), 361 and 364.

4Wallach, Ann. Chem., 227, 287.

5Beilstein and Wiegand, Ber., 15, 2854.

6K wasnick, Ber., 24, 81.

TWallach, Ann. Chem., 258, 340.

72 THE TERPENES.

cones ' and needles? of Abies alba, Russian peppermint oil,? and
Russian and American spearmint oil.

PREPARATION.—The most convenient source of this terpene is
vil of orange peel or caraway oil, and oil of Abies alba. These oils
are dried and fractionally distilled. The fraction boiling at 175°
to 180° is collected. separately, and on redistillation yields limo-
nene, boiling at 175° to 177°, which is not a chemically pure
product.

Properties.—The odor of limonene somewhat resembles that
of lemons. It is optically active and boils at 175° to 176°. The
specific rotatory power has been determined by Wallach and Con-
rady,* as follows :-—

Levo-limonene, [a], = — 105.0°.

Dextro-limonene, Ve p= + 106.8°.

Kremers * found the specific rotatory power of freshly distilled
limonene to be higher, viz. :—

[a] > = 121.3%

He also investigated the rotatory power of limonene in different
solvents.

The specific gravity of levo-limonene at 20° is 0.846, the re-
fractive index, ny = 1.47459, corresponding to a molecular re-
fraction of 45.23 (Wallach).

According to Godlewsky,® when limonene tetrabromide (pre-
pared from carvene, and melting at 104°), is reduced in alcoholic
solution with zinc dust, a limonene is obtained, which, after dry-
ing and distilling over sodium, has the following properties: it
boils at 177.5° under 759 mm. pressure, has a specific’ gravity
0.8441 at 20°, anda specific rotatory power, [a], = + 125° 36’,
at 20°; bromine converts it into the original tetrabromide.

When treated with perfectly dry hydrogen chloride, limonene
yields an optically active monohydrochloride; with nitrosyl
chloride an optically active additive product is formed, and with
bromine an active tetrabromide results. If, on the other hand,
limonene be treated with hydrogen chloride in the presence of
water, it is rendered inactive, and yields dipentene dihydrochlo-
ride ; moist hydrogen bromide and iodide act in an analogous man-

1Wallach, Ann. Chem., 246, 221.

*Bertram and Walbaum, Arch. Pharm., 231, 290.

3Andres and Andrejew, Ber., 1892, 609.

4Wallach and Conrady, Ann. Chem., 252, 144.

5Kremers, Amer. Chem. Journ., 17, 692.

6J. Godlewsky and Roshanowitsch, Chem. Centr., 1899, I., 1241; J. Russ.
Chem. Soc., 31, 209.

LIMONENE TETRABROMIDE. 73

ner. Limonene is also rendered inactive by heating to high tem-
peratures ( Wallach’).

Limonene tetrabromide,’ C,,H,,Br,, is prepared from the fraction
boiling at 174° to 176° of the oil of sweet orange peel, or oil from
cones of Abies alba.

Dissolve the terpene in four times its volume of glacial acetic
acid, cool with ice water, and gradually add bromine from a
dropping funnel until the liquid no longer absorbs it. Crystals
separate at once, and are filtered off with the aid of the pump;
they are pressed on a porous plate, and recrystallized from an
equal weight of acetic ether. The yield is about the same as the
weight of limonene employed.

In regard to the preparation of limonene tetrabromide, com-
pare Baeyer and Villiger,* and Power and Kleber.*

Limonene tetrabromide is optically active, and separates in
hemihedral rhombic ecrystals,° which melt at 104° to 105°.

If hydrobromic acid is eliminated from limonene tetrabromide
by heating with alcoholic potassium hydroxide, two molecules of
hydrogen bromide are split off, while one bromine atom suffers
replacement by one alcohol radical. Thus, if a solution of po-
tassium hydroxide in methyl alcohol be employed, the reactions
take place in accordance with the following equations :—

I. C,)H,,Br,+KOCH,—C,,H,,BrOCH,+KBr.

The resulting compound, C,,H,,BrOCH,, is an oil, which boils
at 137° to 140° under 14 mm. pressure, and has a specific
gravity of 1.251 and coefficient of refraction, np = 1.519638, at
18°. When treated with a solution of hydrogen bromide in
glacial acetic acid, this oil gives a quantitative yield of dipentene
_ tetrabromide. If sodium is added to an alcoholic solution of this
oil, the atom of bromine in this compound, C,,H,,BrOCH,, is re-
placed by hydrogen, and carveol methyl ether, C,,H,,OCH,, is
formed. The latter compound is an optically active oil, boiling
at 208° to 212°, and has a specific gravity of 0.9065 and coef-
ficient of refraction, np = 1.47586, at 18°. This carveol methyl

1Wallach, Ann. Chem., 227, 301.

2Wallach, Ann. Chem., 225, 318; 239, 3; 264, 12; Scheidt, Inaug. Diss.,
Bonn, 1890.

3aeyer and Villiger, Ber., 27, 448; compare Godlewsky, Chem. Zeit., 22,
827.

4Power and Kleber, Arch. Pharm., 232, 646.

5Hintze, Zeitschrift fiir Krystallographie, 10 [2].

6Wallach, Ann. Chem., 281, 127; 264, 12.

74 THE TERPENES.

ether is converted into inactive carvone by oxidation with a solu-
tion of chromic acid in acetic acid.

On the other hand, a conversion of carvone into limonene is
said to be accomplished by the following method.’ Dextro-car-
vone is reduced to dihydrocarveol, which is readily converted into
methyl dihydrocarvyl xanthate, C,,H,,.O.CS,.CH, ; this substance
is a thick oil, and, on distillation, yields two hydrocarbons, boiling
at 172° to 173.5° and 174° to 176°, respectively. The higher
boiling hydrocarbon may be converted into limonene tetrabromide,
which, by the action of zinc dust on its alcoholic solution, yields
pure dextro-limonene.

A liquid limonene tetrabromide is also known, and is readily
formed when bromine is added to the hydrocarbon dissolved in a
perfectly dry solvent.’

Limonene nitrosochlorides, C,,H,,NOCI, are known in four
modifications; by the action of nitrosyl chloride, dextro- and
levo-limonene each yields two optically active isomerides, distin-
guished as a- and f-limonene nitrosochlorides. There are, there-
fore, four isomeric, optically active limonene nitrosochlorides, and
corresponding to them, are two inactive modifications, the a- and
f-dipentene nitrosochlorides.

PREPARATION OF THE NITROSOCHLORIDES FROM
DEXTRO- AND LEVO-LIMONENE.*

To a mixture of five cc. of limonene, seven cc. of amyl
nitrite (or eleven ce. of ethyl nitrite), and twelve cc. of glacial
acetic acid, well cooled by a mixture of ice and salt, add slowly
and in small portions at a time a mixture of six cc. of crude
hydrochloric acid and six ce. of glacial acetic acid. Finally add
five cc. of alcohol and allow to stand for some time in the freez-
ing mixture. A mass of crystals consisting of the crude nitroso-
chloride separates, is filtered with the pump and washed with
alcohol. One hundred grams of nitrosochloride are obtained
from 120 grams of limonene.

SEPARATION OF THE a- AND §-LIMONENE NITROSOCHLOR-
IDES.

One hundred grams of the white and perfectly dry, crude
product are digested with 300 grams of chloroform for a few

1L. Tschigaeff, Ber., 33, 735.
*Wallach, Ann. Chem., 281, 137.
sWallach, Ann. Chem., 252, 106; 270, 174.

LIMONENE NITROSOCHLORIDES. 75

moments in the cold. It is then filtered, and the crude $-com-
pound remaining on the filter is washed with a little chloroform.

An excess of methyl alcohol is added to the filtrate, thus pre-
cipitating the a-compound as a crystalline powder. The crude
a-nitrosochloride is filtered, dried, and digested in a flask with
two to three times its quantity of dry ether for one-quarter of
an hour, care being taken to keep the mixture cold. It is then
filtered, and the ether allowed to evaporate, when the a-com-
pound generally separates in large crystals; they are rubbed
up with methyl alcohol, again dissolved in twice their weight of
ether, filtered, and some methyl alcohol is added to the filtrate.
By the slow evaporation of the solution, pure a-limonene nitro-
. sochloride is obtained in large, brilliant crystals, which melt at
103° to 104°.

a-Limonene nitrosochloride separates in monoclinic crystals ;
together with holohedral forms, hemimorphic crystals are always
~ found, which in the case of the dextro-limonene derivative have
the clinodome on the left, while those of the levo-compound have
the clinodome on the right.

a-Limonene nitrosochloride is soluble at ordinary temperature
in one part of chloroform, and in two parts of ether. It quickly
decomposes on standing.

The crude f-limonene nitrosochloride is dried and dissolved in
ten times its weight of chloroform. The solution is filtered
and precipitated with methyl alcohol in such a manner that a
further addition of this reagent causes a slight additional pre-
cipitate. Thus, the most difficultly soluble portion of the nitro-
sochloride is obtained ; it is filtered, washed with ether and dried.
The dry substance is again digested with three times its weight
of ether, and, on evaporation of this solvent, pure /-limonene
nitrosochloride is obtained; after drying, this compound forms
soft needles, which melt at about 100°. The -nitrosochlorides
may be kept for a long time without decomposing. The crude
limonene nitrosochlorides contain only about twenty per cent. of
the £-nitrosochlorides.

(For the influence of the concentration of the hydrochloric acid on
the yield of f-nitrosochlorides, compare experiments of Wallach.* )

According to Wallach,” the a- and f-nitrosochlorides are phys-
ical, and not chemical isomerides. While Wallach gives them the
formula,

1
CHK OH

1Wallach, Ber., 28, 1308 and 1474.
2Wallach, Ann. Chem., 252, 113; 270, 185.

76 THE TERPENES.

Baeyer! is inclined to consider these compounds as possessing
double that molecular weight, and to regard them as bisnitrosyl-
derivatives. Wallach? has, however, published the results of ex-
periments, which indicate that the a- and f-nitrosochlorides actu-
ally possess twice the molecular weight of the above formula, but
in all other relations they both behave as mono-molecular com-
pounds,

When heated with alcoholic potash, a- and f-limonene nitroso-
chlorides form the same carvoxime, melting at 72°.

Benzoyl limonene nitrosochloride,*

als
C
*""\NOCOC,H;

is formed by adding one molecule of benzoyl chloride to a solu-
tion of one part of a-limonene nitrosochloride in two parts by
weight of dry ether and allowing the mixture to stand for one or
two weeks.

It may also be readily obtained by warming f-limonene nitroso-
chloride with one molecule of benzoy] chloride and eighty times its
weight of dry ether for several days ona water-bath. Benzoyl lim-
onene nitrosochloride melts at 109° to 110°, is difficultly soluble
in ether, easily soluble in acetic ether, and is optically active. It
yields carvoxime * by boiling with sodium alcoholate.

Limonene nitrosobromide,’ C,,H,,- NOBr, is obtained by a method
analogous to that used in the preparation of the nitrosochloride.

It melts at 90.5°.
nee
*””’\NOH

Limonene nitrosate,°
is an oil, which solidifies only at a very low temperature ; it also
yields carvoxime by treatment with alcoholic potassium hydroxide.

LIMONENE NITROLAMINES.®

If dextro-a-limonene nitrosochloride be treated with an organic
base, two isomeric nitrolamines are formed, one of which is-

1Baeyer, Ber., 28, 648.

2Wallach, Ber., 28, 1308 and 1474.
3Wallach, Ann. Chem., 270, 175.
*Wallach, Ber., 28, 1311.

5Wallach, Ann. Chem., 245, 258.
SWallach, Ann. Chem., 252, 113; 270, 180.

LIMONENE NITROLANILIDES. 77

optically dextrorotatory and is called a-nitrolamine, the other is
levorotatory, and termed f-nitrolamine. If dextro-f-limonene
nitrosochloride be treated with the same base, exactly the same
reaction-products are obtamned, namely, a dextrorotatory a-limo-
nene nitrolamine, together with a levorotatory f-limonene nitro-
lamine. If, on the other hand, levo-a- or levo-f-limonene
nitrosochloride be treated with an amine, a mixture of a levo-
rotatory a- and a dextrorotatory #-limonene nitrolamine is formed.
These a- and f-nitrolamines have simple molecules (Wallach’),

If equal proportions of the two oppositely active a-, or P-limo-
nene nitrolamines are recrystallized together, the corresponding
a- or f-dipentene nitrolamine is obtained. These may also be
prepared together by a precisely analogous method from the a-, as
well as from the f-, dipentene nitrosochloride. The following
table may serve to explain these transformations (page 78).

1. Limonene nitrolanilides,

C,H, Z

"\NHCH;

Twenty grams of pure a-limonene nitrosochloride are pulver-
ized and warmed with twenty cc. of aniline and thirty cc. of
alcohol in a flask fitted with a reflux condenser. The mixture is
heated with constant shaking until a reaction commences. After
the violent reaction has taken place, the mass is allowed to cool,
and treated in the cold with an excess of concentrated hydrochlo-
ric acid. The resulting mass of crystals is filtered, and washed
with alcohol and ether. These crystals consist of the hydrochloric
acid salt of a-limonene nitrolanilide. The free a-base is obtained
by treating the hydrochloride with ammonia. a-Limonene nitrol-
anilide crystallizes from alcohol in monoclinic crystals, which —
melt at 112° to 113°. The yield of the a-base is about eighty
per cent. of the theoretical.

In order to obtain the -anilide, the alcholic-acid filtrate from
the hydrochloride of the a-base is poured into a large excess of
ammonium hydroxide. The f-anilide gradually solidifies, and is
dissolved in three times its weight of benzene in order to remove
any aniline which may cling to it. Most of the f-anilide sepa-
rates from this solution on cooling, while the remainder may be
precipitated by the addition of petroleum ether. -Limonene
nitrolanilide crystallizes from alcohol in moss-like needles, which
melt at 153°. It is difficultly soluble in ether, readily soluble in
chloroform.

1Wallach, Ber., 28, 1311.

THE TERPENES.

78

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LIMONENE NITROLBENZYLA MINES. 79

When the glacial acetic acid solution of the a-, or the hydro-
chloric acid solution of f-, limonene nitrolanilide is treated with
a solution of sodium nitrite, nitroso-compounds,

JNOH
C.
BP eienct:
are formed. The a-nitroso-compound melts at 142°, while the.
f-derivative, characterized by its great power of crystallization,
melts at 136°.

2. Limonene nitrolpiperidides,

JNOH

C,H
10 *\NCHis

Twenty grams of pure pulverized a-limonene nitrosochloride are
covered with twenty grams of piperidine and sixty grams of
alcohol, and gently warmed with frequent shaking. When a clear
solution is obtained, the warm liquid is poured into an evaporat-
ing dish and a small quantity of water added. On cooling, cry-
stals of the very sparingly soluble, impure /-base separate.
These are filtered, and the readily soluble, impure a-base is pre-
cipitated from the filtrate by water. ‘The purification of these
compounds is based on the circumstance that the £-piperidide is
sparingly, the a-base extremely easily, soluble in petroleum ether.
The crude a-base is first dissolved in acetic acid, filtered to
remove the non-basic impurities, and again thrown out with am-
monia. It first appears as an oil which solidifies after a little
time. It is dried, digested with a small amount of petroleum
ether, decanted from the undissolved f-base, and, after evapora-
tion of the petroleum ether, is recrystallized from alcohol.

a-Limonene nitrolpiperidide separates in orthorhombic crystals,
and melts at 93° to 94°.

The crude f-base is dried, digested with cold petroleum ether,
and the undissolved portion recrystallized from warm petroleum
ether with the addition of some methyl alcohol. /-Limonene
nitrolpiperidide melts at 110° to 111°.

3. Limonene nitrolbenzylamines,

NOH

se

Two bases are formed by the action of limonene nitrosochloride

_ on benzylamine ; only the a-amine, however, has been obtained in
a condition of purity. It forms hard needles, melting at 93°.

80 THE TERPENES.

This base yields a nitrate, which forms splendid crystals, and is
very sparingly soluble in water.

Emil Fischer! and other investigators have suggested that the
isomerism of the a- and f-limonene nitrolamines is to be explained
as stereo-chemical isomerism. According to Wallach,” however,
the known facts do not determine whether the a- and f-limonene
nitrolamines, in contrast to the nitrosochlorides, have the same or
different chemical structure. The following observations argue
against the stereo-chemical theory.’

1. No transformations of the a- into the f-limonene nitro-
lamines, or the f- into the a-derivatives, have yet succeeded.

2. a-Limonene nitrolanilide is a weaker base than f§-limonene
nitrolanilide.

3. On heating, the a-anilide yields aniline and a product con-
taining carvoxime ; the f-anilide, under the same circumstances,
gives aniline and an isonitrile.

4, a-Limonene nitrolanilide in a methyl alcohol solution is cap-
able of adding the elements of hydrochloric acid, forming a com-
pound which melts at 115°. The latter substance is apparently
identical with hydrochlorolimonene nitrolanilide,

ol
C,H
0" NNB.C,H;

obtained from hydrochlorolimonene nitrosochloride. Under the
same conditions, f-limonene nitrolanilide forms a compound,
C,,H,,CIN,O, which melts at 78°; a substance similar to this
compound has not yet been prepared from hydrochlorolimonene
nitrosochloride.

It should be noted that a- and f-limonene nitrolanilides possess
the same molecular weight (determined by the boiling point
method, dry ether being the solvent).

Limonene hydrochloride, C,,H,,: HCl.

Limonene, well dried over metallic sodium, is diluted with an
equal volume of perfectly dry carbon bisulphide, and saturated
with dry hydrochloric acid gas. The liquid must be well cooled
with ice, and every precaution used to avoid the presence of any
trace of water. One hundred grams of limonene require
twenty-four hours for the saturation. When this point is reached,
the excess of hydrochloric acid and carbon bisulphide is removed

1Emil Fischer, Ber., 23, 3687; 24, 2686.
Wallach, Ann. Chem., 270, 186.

HYDROCHLOROLIMONENE NITROSATE, 81

by distillation under diminished pressure, and the resulting limo-
nene monohydrochloride rectified in vacuum (Wallach, Kremers').

Optically active limonene hydrochloride forms a colorless oil,
boiling at 97° to 98° under 11 mm. to 12 mm. pressure. A
product obtained from dextro-limonene had the specific gravity
of 0.973 at 17.8°, while that obtained from levo-limonene had
the specific gravity of 0.982 to 16°."

Limonene hydrochloride appears to readily change into an in-
active modification on standing. This transformation is accom-
panied by polymerization of the substance.

Although limonene hydrochloride (like its inactive modification,
dipentene hydrochloride) behaves as a saturated compound to-
wards dry hydrochloric acid, it unites with the halogens, nitrosyl
chloride, etc., forming additive compounds.

When allowed to remain in contact with water in a sealed glass
tube for some months, limonene hydrochloride forms crystals of
terpine hydrate. Alcoholic potassium hydroxide eliminates the
elements of hydrogen chloride from limonene hydrochloride. In
an acetic acid solution it unites with hydrochloric acid, forming
dipentene dihydrochloride, while under the same conditions,
hydrogen bromide converts it into a compound melting at 47°
to 48°.

According to a preliminary notice by Semmler,’ the chlorine
atom in limonene hydrochloride can be replaced by a hydroxyl-
group, thus forming an optically active terpineol.

Hydrochlorolimonene nitrosochloride, C,,H,,Cl - NOCI, is obtained
by the gradual addition of twenty-five cc. of a five to six per
cent. solution of hydrochloric acid in glacial acetic acid to a well
cooled mixture of five cc. of limonene hydrochloride, ten cc. of
methyl alcohol and seven and one-half cc. of amyl nitrite. Water
is then added until the liquid commences to appear cloudy, when
the nitrosochloride separates gradually. It is purified by dissolv-
ing in chloroform and precipitating with methyl alcohol. It melts
at 109° (Wallach °).

Hydrochlorolimonene nitrosate,* C,,H,,Cl: NO(ONO,), is pre-
pared by treating a very cold mixture of one molecule of limonene
hydrochloride and one molecule of amyl nitrite with one molecular
proportion of sixty per cent. nitric acid. The mixture should be
agitated during the addition of the nitric acid. The nitrosate
separates as a white, crystalline precipitate. The yield can be
increased by the final addition of alcohol. Hydrochlorolimonene

1Wallach and Kremers, Ann. Chem., 270, 188.
2Semmler, Ber., 28, 2189-
3Wallach, Ann. Chem., 245, 260.

§

82 THE TERPENES.

nitrosate was first obtained by Maissen’; its constitution was ex-
plained by Wallach’s investigation. It melts at 108° to 109°.
Hydrochlorolimonene nitrolamines,

NO
C,H ag
10417 NHR

Hydrochlorolimonene nitrosate is best employed for the prepara-
tion of these compounds, since it is more difficultly soluble, and
more readily obtained than the corresponding nitrosochloride ; the
following general observation, however, should be noted in prepar-
ing these amines. It has been mentioned that limonene hydro-
chloride is readily converted into the inactive modification. Con-
sequently, some inactive hydrochlorodipentene nitrosate is often
obtained during the preparation of hydrochlorolimonene nitrosate.

If the preparation of the active hydrochlorolimonene nitrola-
mines be desired, the most soluble portions of hydrochlorolimonene
nitrosate, prepared according to method described, are employed,
since hydrochlorodipentene nitrosate is more difficultly soluble
than the active modifications, and separates out before the active
derivatives (Wallach’).

Hydrochlorolimonene nitrolbenzylamine,’”

ane NO
ica Ag aie

is prepared by warming a mixture of five parts of hydrochloro-
limonene nitrosate, ten parts of alcohol and four parts of benzyl-
amine for a short time, until the reaction begins. The inactive
dipentene base separates in fine needles on cooling. The active
base is precipitated from the filtered solution by the addition of
water. It is very readily soluble in alcohol, ether and benzene,
only sparingly soluble in cold petroleum ether from which it is
recrystallized.. It is optically active, melts at 103° to 104°, and
yields an optically active hydrochloride, which crystallizes from
alcohol in fine needles, melting at 163° to 164.°

Hydrochlorolimonene nitrolanilide,’

NO
OnE

is conveniently prepared by the following method. Three and
one-half cc. of aniline are added to a warm solution of five grams

1Maissen, Gazz. Chim., 13, 99.
Wallach, Ann. Chem., 270, 191.

OXIDATION PRODUCTS OF LIMONENE. 83

of hydrochlorolimonene nitrosate in thirty-five grams of benzene.
Aniline nitrate is formed, and after a few minutes is filtered off ;
small quantities of inactive hydrochlorodipentene nitrolanilide
separate with the aniline nitrate.

To obtain the hydrochlorolimonene nitrolanilide, the benzene
filtrate is shaken with hydrochloric acid. The hydrochloride of
the nitrolanilide separates as a solid, while the excess of aniline
is taken up by the hydrochloric acid ‘solution, and other impuri-
ties are dissolved in the benzene. The filtered hydrochloride is
rubbed up with ammonium hydroxide, and the free nitrolamine
crystallized from alcohol.

Hydrochlorolimonene nitrolanilide melts at 117° to 118°. A
compound, ys

“aot NHGH,
obtained by the addition of hydrogen chloride to limonene nitrol-
anilide, melts at 115°; it has not been determined with certainty
whether this compound is identical with hydrochlorolimonene
nitrolanilide.'

When hydrochlorolimonene nitrolanilide is treated with alco-
holic potash, tarry products are obtained from which no bases free
of chlorine have yet been separated in a crystalline condition.
(Compare with dipentene derivative, page 97.)

The condensation-product,’ C,,H,,O, is produced by heating
limonene and paraformaldehyde - in alcoholic solution in a closed
tube, at 190° to 195°, for several hours; it is a colorless liquid,
boils at 246° to 250°, has the specific gravity 0.9568 at 20°, and
its optical rotation corresponds to that of the limonene employed.
Its acetyl derivative boils at 259° to 263°.

The action of nitrous fumes on dextro-limonene cooled by ice
and salt gives rise to an alcohol, limonenol,* C,,H,,OH.

OXIDATION PRODUCTS OF LIMONENE.

The earlier publications‘ regarding the oxidation of limonene
state that a chromic acid mixture converts limonene into carbonic
anhydride, acetic acid, and a liquid camphor, C,,H,,O, but
that nitric acid oxidizes it to oxalic acid and_hesperic acid,

C,,H,,O,, + 2H,O. Tilden and Williamson® showed that when

1Wallach, Ann. Chem., 270, 187 and 194.

20. Kriewitz, Ber., 32, 57.

3P. Genvresse, Compt. rend., 132, 414.

4Wright, Jahresb. Chem., 1873, 369; Sauer and Griinling, Ann. Chem.,
208, 75.

6Tilden and Williamson, Journ. Chem. Soc., 63 (1893), 293; 53 (1888),
880.

.)
——-—

84 THE TERPENES.

this terpene is oxidized with nitric acid, neither toluic acid nor f
terephthalic acid is formed.

G. Wagner’ obtained a tetrahydric alcohol, limonetrol, C,,H,,-
(OH), by the oxidation of limonene with potassium perman-

anate.

¢ According to Godlewski,’ oryterpenylic decid, C,H,,O,, is pro-
duced, when limonene, free from carvone, is oxidized with potas-
sium permanganate ; it melts at 174.5°, and is identical with the
acid obtained by Best* in the oxidation of carvone with perman-
ganate. The dilactone of the acid, C,H,,O,, melts at 129° to
130°, and is reconverted into oxyterpenylic acid by the action of
potassium hydroxide.

Semmler* has suggested that those terpene derivatives which
contain a double linkage between the nucleus and the side chain
shall be termed pseudo-derivatives, and the isomeric compounds
containing the double bond in the nucleus, ortho-derivatives. In
accordance with this suggestion, limonene, which is regarded as
having the formula,

fs

x

should be called ortho-limonene. The isomeric, pseudo-limonene,
would have the formula,

H
H,
H;

u,¢6 Yu,

1G. Wagner, Ber., 1890, 2315.

*J. Godlewsky, Chem. Centr., 1899 (I.), 1241; Journ. Russ, Chem. Soc.,
$81 (1899), 211.

30. Best, Ber., 27, 1218.

‘F. Semmler, Ber., 33, 1455.

DIPENTENE. 85

‘Semmler thinks that it is not improbable that dipentene has the
latter formula, and that it is not an inactive modification of limo-
nene, as is generally assumed. He further states that both com-
pounds would yield the same derivatives by the action of halogen
acids. (In a subsequent investigation Semmler’ concludes that
terpinene is to be regarded as pseudo-limonene.)

It should also be mentioned that Baeyer? has succeeded in con-
verting certain monocyclic terpenes into corresponding derivatives
of benzene. Thus, limonene is converted into dipentene dihydro-
bromide by treatment with a glacial acetic acid solution of hydro-
gen bromide; the dry dihydrobromide is added to bromine, some
iodine being introduced, and the mixture allowed to stand until
no further evolution of hydrogen bromide is noticed. On treat-
ing the product with an alcoholic solution of hydrochloric acid
and zine dust, and then with sodium and alcohol, para-cymene is
obtained.

The values for the rotatory powers of the limonene derivatives
are given in the following table. These values were obtained in
the extended investigations of Wallach, Conrady and Kremers.

The dextro- and levo-limonene derivatives agree completely in
their power of rotation, provided they are obtained in a pure con-
dition. A reversal in the direction of rotation takes place when
salts are prepared from basic compounds, when limonene nitro-
sochloride is converted into carvoxime, and when f-nitrolamines
are formed from the nitrosochlorides ; the a-nitrolamines, which
are formed together with the f-nitrolamines, rotate the plane of
polarized light in the same direction as the original nitrosochlo-
rides.

4b. DIPENTENE.

Dipentene is the optically inaetive modification of limonene
and bears the same relation to the latter as racemic acid to the
optically active tartaric acids (Wallach).

Dipentene is widely distributed in many ethereal oils, and is
also formed by heating different terpenes and polyterpenes to a
high temperature. According to its source, it has been described
under various names, such as di-isoprene, terpilene, caoutchin,
cinene, cajeputene, isoterebentene, etc. Wallach*® showed, how-
ever, that all these substances contain dipentene as their principal
constituent, and are, therefore, to be regarded as identical.

1Semmler, Ber., 34, 708.

*Baeyer and Villiger, Ber., 31, 1401.

’Wallach and Brass, Ann. Chem., 225, 309; Wallach, Ann. Chem., 225,
314; 227, 293.

THE TERPENES,

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DIPENTENE. 87

Dipentene is contained in camphor oil,’ Russian * and Swedish
turpentine oil,? oil of pine needle from Picea excelsa,* oil of
cubebs, oil of limetta leaf, oil of kesso-root, oil of olibanum,‘ oil
of mace,‘ oil of wormwood,' oil of bergamot, oil of fennel, oil of
kuromoji,° oil of myrtle, oil of pepper, oil of cardamom, oil of nut-
meg, oil of golden rod, oil of massoy bark, oil of thyme (from
Thymus capitatus), and oil of wormseed.

It is always formed when terpenes are heated to high tempera-
tures, hence it is found in Russian and Swedish turpentine oils,”
as well as in the products of the distillation of pine roots and fir-
wood.® Dipentene is also obtained from the distillation products
of vegetable resins, as copal resin, soft Elemi resin and colo-
phonium.’ Essence of resin also contains dipentene as shown by
Renard’s ® experiments, which will be mentioned later.

Dipentene is produced under various conditions from many
compounds of the terpene series. It is formed, together with
higher boiling polymerides, by heating isoprene,’ C,H,, at 250°
to 270° ; it is also found with isoprene in the products of the dry
distillation of caoutchouc.” Pinene is converted into dipentene
by heating to 250° to 270°." Dipentene is obtained by mixing
equal quantities of dextro- and levo-limonene ;"' limonene also be-
comes inactive by heating to high temperatures. A transforma-
tion of pinene into dipentene may also be effected by the action
of dilute, or alcoholic, sulphuric acid.

Dipentene is derived from many oxidized compounds of the
terpene series by the elimination of water. According to Wal-
lach and Brass,’* cineole, C,,H,,O, may be converted into dipentene
by heating with hydrochloric acid gas, or by heating with ben-
zoyl chloride, or by an indirect method depending on the forma-
tion of dipentene dihydriodide from cineole and hydriodic acid ;
by elimination of hydrogen iodide from this dihydriodide, dipentene
is prepared. ‘Terpine hydrate gives dipentene on warming with

1Wallach, Ann. Chem., 227, 296.

2*Wallach, Ann. Chem., 230, 244 and 246.

3Bertram and Walbaum, Arch. Pharm., 231, 290.

4Wallach, Ann. Chem., 252, 100.

5Kwasnick, Ber., 24, 81.

6Aschan and Hjelt, Chem. Ztg., 18, 1566.

TWallach and Rheindorf, Ann. Chem., 271, 310.

8Renard, Ann. Chim. Phys. (6), 1, 223.

8Wallach, Ann. Chem., 227, 295; Bouchardat, Compt. rend., 89, 1217.

WWallach, Ann. Chem., 227, 295; Bouchardat, Compt. rend., 80, 1446; 89,
1217; Tilden, Journ. Chem. Soc., 1884 (45) ,410; Jahresb. Chem., 1882,405.

Wallach, Ann. Chem., 246, 225.

12Wallach, Ann. Chem., 227, 289.

*3Wallach, Ann. Chem., 230, 255.

88 THE TERPENES.

acid potassium sulphate,’ or by boiling with a twenty per cent.
phosphoric acid solution. Terpineol, C,,H,,OH, yields dipentene
when heated with acid potassium sulphate.’

Of especial interest is the formation of dipentene from linalool ;
according to Bertram and Walbaum,’ the action of formic acid,
sp. gr. 1.22, converts linalool, an unsaturated, optically active,
aliphatic alcohol, into dipentene and terpinene.

All these methods of preparation of this terpene yield an impure
product. In order to obtain chemically pure dipentene, the halo-
gen hydride addition products are employed, the dihydrochloride
being particularly well adapted. Hydrochloric acid may be
eliminated from this substance by boiling with aniline,* or better
with sodium acetate.

PREPARATION.°—One part by weight of dipentene dihydro-
chloride is boiled with one part of anhydrous sodium acetate
and two parts of glacial acetic acid for half an hour in a flask
provided with a reflux condenser. The product is distilled with
steam, the volatile oil separated and boiled for some time with
potassium hydroxide ; it is then redistilled with steam, dried and
purified by fractional distillation (Wallach).

PROPERTIES.—Since dipentene is inactive limonene, the boiling
points of both compounds, when pure, are the same. The biblio-
graphical references, however, give the boiling point of dipentene
rather higher than that of limonene. These differences are to be
traced to the varying degrees of purity of the hydrocarbons.
Wallach found the boiling point of dipentene, prepared from
the dihydrochloride by means of aniline, to be 178°; it had
the specific gravity of 0.845 at 20° and the refractive index,
n= 1.47308.°

A relatively pure dipentene, prepared by the dry distillation of
caoutchoue, boils at 175° to 176°, has the sp. gr. 0.844 and the
refractive index, ny = 1.47194, at 20° (Schimmel & Co.).

According to Tilden and Williamson,’ dipentene, obtained from
the dihydrochloride by the action of aniline, contains cymene, ter=
pinene, terpinolene and a saturated hydrocarbon similar to paraffin;
when oxidized with nitric acid it gives a considerable quantity of
toluic acid.

1Wallach, Ann. Chem., 230, 255.

*Wallach, Ann. Chem., 275, 104; 291, 342.

sBertram and Walbaum, Journ. pr. Chem., N. F., 45, 601.
‘Wallach, Ann. Chem., 227, 286; 245, 196.

5Wallach, Ann. Chem., 239, 3.

6Wallach, Ann. Chem., 245, 197.

"Tilden and Williamson, Journ. Chem. Soe., 1893 (63), 292.

DIPENTENE DIHYDROCHLORIDE. 89

Dipentene polymerizes at high temperatures without previous
conversion into an isomeric terpene. It is, therefore, characterized
by its relative stability ; but, nevertheless, it may be changed into
terpinene.’

This transformation into terpinene, accompanied by a consider-
able polymerization of the terpene, takes place when dipentene is
warmed with alcoholic sulphuric acid. Further, if dipentene
dihydrochloride be boiled with alcohol for some time, terpinene is
produced by the withdrawal of hydrochloric acid. These reactions
indicate that terpinene, which is always obtained together with
dipentene by boiling terpine hydrate or terpineol with concen-
trated mineral acids, is a secondary product, resulting from the
dipentene primarily formed. On shaking with an equal volume of
concentrated sulphuric acid, dipentene is converted into cymeme
sulphonic acid and cymeme, with evolution of sulphur dioxide ;
cymene also results by the action of phosphorus pentasulphide on
dipentene.

The following derivatives of dipentene, without exception, may be
prepared not only from dipentene, but also by combining equal parts
by weight of the corresponding dextro- and levo-limonene derivatives.

Dipentene hydrochloride,’ C,,H,,. HCl, is obtained by the same
method as limonene hydrochloride ; it is likewise formed when equal
volumes of dextro- and levo-limonene hydrochlorides are mixed
(Wallach *). This compound, like its active components, is not
changed by dry hydrogen chloride ; with moist hydrochloric acid,
it forms dipentene dihydrochloride. It forms additive products
with bromine, nitrosyl chloride, etc. It is only distinguished
from limonene hydrochloride by its lack of optical activity.

Dipentene dihydrochloride, C,,H,,.2HCI, is formed by the action
of moist hydrochloric acid on numerous compounds of the terpene
series which are related to dipentene. It is obtained by satu-
rating the alcoholic, ethereal or acetic acid solution of dipentene,
and also of pinene and limonene, with hydrochloric acid gas.

~It further results by the action of hydrochloric acid on terpine
hydrate, terpineol and cineole.

In order to prepare dipentene dihydrochloride, dilute limonene
with one-half its volume of glacial acetic acid, and pass a current of
hydrochloric acid gas over, not into, the well cooled liquid, with
frequent shaking. Every rise in temperature of the liquid,
which would lead to the formation of oily by-products, may thus

1Wallach, Ann. Chem., 239, 15.

2Wallach, Ann. Chem., 245, 247; 270, 188.

$Wallach, Ann. Chem., 270, 189; 245, 247; Riban, Jahresb. Chem., 1874,
397; Bouchardat, Bull. Soc. Chim., 24, 108.

90 THE TERPENES.

be prevented. As soon as the mass becomes solid, shake with
water, filter, press on a porous plate, and purify the product by
dissolving in alcohol and precipitating with water (Wallach *).

Dipentene dihydrochloride melts at 50°, and boils at 118° to
120° under a pressure of 10 mm.” It is easily soluble in alcohol,
ether, chloroform, ligroine, benzene, and glacial acetic acid. Its
conversion into dipentene, as well as its transformation into ter-
pinene by boiling with alcohol, has already been mentioned ; on
standing with alcohol, terpine hydrate is formed. The products
of the action of sodium, and sodium ethylate on this compound
have been investigated by Montgolfier,* and Tilden.* By warm-
ing with a little ferric chloride solution, dipentene dihydrochlo-
ride gives a rose color, which passes into a violet-red and finally
into a blue (Riban).

This dipentene dihydrochloride belongs to the trans-series. Ac-
cording to Baeyer,’ a cis-dipentene dihydrochloride, melting at
about 25°, is obtained if a well cooled glacial acetic acid solution
of cineole be treated with hydrochloric acid.

Monochlorodipentene dihydrochloride,’ C,,H,Cl,, is obtained
when dry chlorine is conducted into a solution of dipentene
dihydrochloride in three times its amount of carbon bisulphide ;
the chlorination is best performed in the direct sunlight, or after
the addition of some aluminium chloride to the solution. The
liquid first becomes cloudy, and then exceedingly warm; during
the course of the reaction a violent evolution of hydrogen chloride
takes place. The chlorinating action is continued until the liquid
appears clear, and has a yellow color. If the operation is success-
ful, the carbon bisulphide is allowed to evaporate, and the result-
ing crystalline product is pressed on a porous plate and recrystal-
lized from alcohol. In other cases, the trichloride is separated
from admixed dipentene dihydrochloride and tetrachloride, the
latter remaining in the residue, by fractional distillation in
vacuum ; the trichloride boils at 145° to 150° under 10 mm.
pressure. It crystallizes from alcohol in brilliant, white leaflets,
which melt at 87°.

The behavior of this trichloride and of the corresponding bro-
mine derivative towards reagents capable of eliminating halogen

hydrides is quite different. Thus, when monobromodipentene ;

Wallach, Ann. Chem., 245, 267.

?Wallach, Ann. Chem., 270, 198.
sMontgolfier, Ann. Chim. Phys. (5), 19, 155.
‘Tilden, Jahresb. Chem., 1878, 639.

5Baeyer, Ber., 26, 2863.

SWallach and Hesse, Ann. Chem., 270, 196.

9 OO onto

DIPENTENE DIHYDROBROMIDE. 91

dihydrobromide, which melts at 110° and is prepared from dipen-
tene dihydrobromide, is treated with alcoholic potash, a hydro-
carbon, C,,H,,, is obtained; the trichloride, however, yields a
product consisting principally of an wnsaturated, liquid dipentene
dichloride when it is submitted to the action of sodium alcoholate
or sodium acetate (Wallach and Hesse'). This liquid dichloride
was not obtained pure, but was converted into the original tri-
chloride (m. p. 87°) by the action of hydrochloric acid; with
bromine, it gave a compound, C,,H,,Cl,Br,, melting at 98°. It
formed a nitrosochloride, melting at 111°, which was converted
into a nitrolanilide,
NO

NHC,H;

CipHi6Cl,

melting at 140° to 141°, and a nitrolpiperidide, melting at 147°
and crystallizing from alcohol in brilliant tablets.

Dichlorodipentene dihydrochloride, C,,H,,Cl,, is prepared when
dipentene dihydrochloride, or the above-described trichloride, is
dissolved in carbon bisulphide and treated with chlorine for a
long time; the reaction-products are then distilled in vacuum.
The fraction boiling at 160° to 165° contains most of the tetra-
chloride, and solidifies in the cold. This compound is separated
from admixed trichloride by means of petroleum ether, and is
recrystallized from ethyl acetate; it melts at 108° (Wallach and
Hesse ').

Dipentene dihydrobromide, C,,H,,.-2HBr, was first obtained by
Oppenheim’ by treating terpine with phosphorus tribromide.
Hell and Ritter* prepared the same compound by the action of
hydrobromic acid on wormseed oil. According to Wallach,‘ di-
pentene dihydrobromide is formed by the addition of hydrogen
bromide to dipentene and limonene, or by the treatment of terpine
with hydrobromic acid. The dipentene dihydrobromide, prepared
in a manner similar to that of the trans-dipentene dihydrochloride,
melts at 64°, and, according to Baeyer, belongs to the trans-series.

Cis-dipentene dihydrobromide is produced as a by-product by
some of the above-mentioned methods of preparation of the trans-
compound. It is formed in exceedingly large quantities in the
action of a glacial acetic acid solution of hydrobromic acid on a
well cooled solution of cineole in glacial acetic acid (Baeyer’).

1Wallach and Hesse, Ann. Chem., 270, 196.
Oppenheim, Jahresb. Chem., 1862, 459.
3Hell and Ritter, Ber., 17, 2610.

4Wallach, Ann. Chem., 239, 12.

5Baeyer, Ber., 26, 2863.

92 THE TERPENES.

The melting point of this compound is about 39°. If the solu-
tion is not well cooled during the preparation of this substance,
the trans-compound is formed in large quantities.

When cis-dipentene dibydrobromide is treated with silver ace-
tate in an acetic acid solution, the acetate of the long known ter-
pine hydrate (cis-terpine hydrate, m. p. 117.5°) is formed. Under
the same conditions, trans-dipentene dihydrobromide (m. p. 64°)
yields the acetate of a new crystalline, anhydrous terpine, melting
at 156° to 158°, which is termed trans-terpine (Baeyer).

Dipentene is formed by the elimination of hydrobromie acid
from the trans-, as well as from the cis-, dipentene dihydrobromide.

Monobromodipentene dihydrobromide, C,,H,,Br, (according to
Baeyer, 1, 4, 8-tribromoterpane), is derived from dipentene dihy-
drobromide. As one or two hydrogen atoms in dipentene dihy-
drochloride may be replaced by chlorine, so higher brominated
derivatives of dipentene may be prepared from dipentene dihy-
drobromide by substitution. Among these, the tribromide is
characterized by its power of crystallization.

In order to prepare this compound, two hundred grams of
dipentene dihydrobromide, contained in a flask, are covered with
400 cc. of glacial acetic acid, and thirty-four cc. (not more !) of
bromine are added to the slightly cooled mass, with constant agi-
tation. During this process the temperature should not rise too
high, but, nevertheless, must increase to such an extent that all
dipentene dihydrobromide is dissolved. The liquid is allowed to
stand until the color of the bromine has disappeared, and is then
poured into a crystallizing dish ; three hundred ce. of absolute al-
cohol are added, and the whole is allowed to remain for one day at
the lowest possible temperature. The preparation is most suc-
cessful in the winter.

The resultant crystals are collected; water is added to the
mother-liquor, and the heavy oil which separates is washed with
water, and dissolved in an equal volume of methyl alcohol. Ad-
ditional quantities of the solid tribromide are obtained by placing
this solution in a freezing mixture. The yield of the crude tribro-
mide is about one-third of the weight of the dihydrobromide em-
ployed. It is purified by dissolving fifty grams of the product
in one hundred cc. of warm acetic ether, and subsequently adding
twenty-five cc. of methyl alcohol. The tribromide separates in
brilliant, white leaflets, which melt at 110° (Wallach’).

Baeyer’ obtained the same tribromide by the addition of hydro-
bromic acid to terpinolene dibromide.

1Wallach, Ann. Chem., 264, 25.
2Baeyer, Ber., 27, 450.

2 Sees

TETRABROMIDE. 93

If fifty grams of the tribromide are warmed with a solution of
twelve grams of sodium is one hundred and fifty cc. of alcohol,
an unsaturated hydrocarbon, C,,H,,, isomeric with cymene, results ;
it boils at 183° to 184°, has the specific gravity of 0.863 at 20°,
the refractive index, ny = 1.49693, and the molecular refraction,
45.435 (Wallach’).

Tetrabromide,' C,,H,,Br,—The above-mentioned hydrocarbon,
C,,H,,, forms oily addition-products with the halogen hydrides ; it
yields no crystalline derivatives with the oxides of nitrogen. On
the other hand, a characteristic additive compound with bromine
is obtained if bromine be added to a cold solution of the hydro-
carbon in a mixture of ten volumes of glacial acetic acid and a
little alcohol. The resulting, sparingly soluble bromide, C,,H,,Br,,
separates from ethyl acetate in asymmetric crystals, which melt at
154° to 155°.

A readily soluble bromide, C,,H,,Br, (or C,,H,,Br,?), melting
at 103° to 104°, is formed as a by-product during the bromination
of the hydrocarbon, C,,H.,,.

Baeyer” found that by reducing the above-described tribromide,
C,,H,,Br,, melting point 110°, with zine dust and glacial acetic
acid, the mixture being well cooled, the liquid acetate of a crystal-
line ‘alcohol, C,,H,,OH, melting at 69° to 70°, is formed. In ac-
cordance with ” Baeyer’s proposed nomenclature, this alcohol is
called 4 4(8)-terpen (1)-ol:

A,

—OH
K
H oe
H, V H,

CH, CH;

The tribromide (m. p. 110°) is obtained by the action of
hydrobromic acid on the dibromide of this alcohol (terpenol), as
well as on the dibromide of its acetate.

If the reduction of tribromoterpane (m. p. 110°) be performed
with zine dust in an alcoholic solution, the bromide, C,,H,,Br (1-
bromo-4 (8)-terpene), corresponding to the terpenol above men-
tioned, isformed. It melts at 34° to 35°, and yields a blue nitro-
sobromide, which melts at 44° (Baeyer and Blau *).

1Wallach, Ann. Chem., 264, 25.

2Baeyer, Ber., 27, 444.
3Baeyer and Blau, Ber., 28, 2290.

94 THE TERPENES. .

Dipentene dihydriodide, C,,H,,-2HI, results if hydriodic acid be
passed through well cooled cineole. When the reaction is com-
plete, the crystalline mass is filtered by a pump, washed with a
little aleohol, and recrystallized from petroleum ether (Wallach
and Brass‘). Dipentene dihydriodide is also very conveniently
prepared from terpine hydrate, if this compound be well agitated in
the cold with a concentrated aqueous solution of hydriodic acid
(Wallach’). It may further be obtained from pinene, limonene,
dipentene and terpineol by methods analogous to those for the
preparation of the dihydrochloride and dihydrobromide.*

When recrystallized from petroleum ether, dipentene dihydrio-
dide exhibits two different crystalline forms ; it sometimes erystal-
lizes in rhombic prisms, melting point 77°, often in monoclinic
tablets melting at 78° to 79° (Hintze*).

After Baeyer discovered that dipentene dihydrochloride and
dihydrobromide exist in cis- and trans-modifications, the presump-
tion followed that the difference in the two modifications of dipen-
tene dihydriodide could be explained in asimilarmanner. Wallach®
found, however, that this conjecture was not confirmed ; moreover,
he showed that both ecrystallographically different modifications of
trans-dipentene dihydriodide are formed by the action of phos-
phorus triiodide on terpine, and that at the same time small
quantities of a compound, melting at 50°, are produced ; the latter
substance is much more readily soluble in petroleum ether than
the trans-derivative, and is to be regarded as cis-dipentene dihy-
driodide.

Dipentene dihydriodide is readily soluble in ether, benzene,
chloroform and carbon bisulphide, more sparingly in cold alcohol.
It is rather unstable; iodine is readily and completely removed
from it by an alcoholic silver nitrate solution. It can not, there-
fore, be long preserved, but remains for some time undecomposed
if kept under water with a small piece of phosphorus.

With aniline, alcoholic potash or sodium acetate, dipentene
dihydriodide yields dipentene.®

Dipentene tetrabromide,’ C,,H,,Br,, is prepared in a perfectly
similar manner to limonene tetrabromide. It has a certain his-
torical interest in so far as its discovery marks the beginning of

1Wallach and Brass, Ann. Chem., 225, 300.

2Wallach, Ann. Chem., 230, 249.

3Wallach, Ann. Chem., 239, 13.

4Hintze, Ann. Chem., 239, 14.

5Wallach, Ber., 26, 3072; Ann. Chem., 252, 128.

‘Wallach, Ann. Chem., 281, 243.

TWallach and Brass, Ann. Chem., 225, 305; 227, 279; 246, 226.

at ia

wy

DIPENTENE NITROSOCHLORIDES. 95

Wallach’s investigations. It should also be mentioned that,
almost simultaneous with Wallach, Renard’ obtained a solid
tetrabromide, melting at 120°, from a terpene boiling at 170° to
173° which occurs in essence of resin; this bromide is without
doubt to be regarded as impure dipentene tetrabromide.

Dipentene tetrabromide crystallizes from acetic ether in very
characteristic rhombic crystals, which are more sparingly soluble
in ether than those of limonene tetrabromide. They melt at
125° to 126°, are brittle, and show reed-like striations on the
faces in the vertical zone (Hintze ’).

According to Baeyer,’ dipentene tetrabromide is formed indi-
rectly from terpineol. Terpineol (m. p. 35°) is first converted
into its liquid dibromide,* and this in turn is changed into a liquid
1, 2, 4-tribromoterpane, C,,H,,Br,, by the action of hydrobromic
acid. When the tribromoterpane is dissolved in glacial acetic
acid and treated with two atoms of bromine, a bromide, melting
at 124°, is obtained whose crystals, according to crystallographic
measurement by Villiger, are ‘‘ undoubtedly” identical with the
erystals of dipentene tetrabromide measured by Hintze.”

It should, however, be mentioned that Hintze* has intimated
that this identity does not appear to have been definitely proved
by Villiger’s results. On the other hand, Wallach® confirmed
Baeyer’s statement that dipentene tetrabromide results by the
action of bromine on 1, 2, 4-tribromoterpane.

The products ® obtained by the action of alcoholic potash on
dipentene tetrabromide have not yet been carefully investi-
gated.

Dipentene nitrosochlorides, C,,H,,. NOCI, are known in two
modifications, which are much more soluble, hence less character-
istic, than the corresponding optically active compounds. a-Di-
pentene nitrosochloride, prepared by mixing the solutions of equal
quantities by weight of dextro- and levo-a-limonene nitrosochlo-
ride, does not crystallize as well as the active modifications ; when
heated to 78°, it becomes liquid, again solidifies, and, on increas-
ing the heat, melts at 103° to 104°. {-Dipentene nitrosochlo-
ride has not been isolated in a condition of purity ; it is very read-
ily soluble (Wallach ’).

1Renard, Ann. Chim. Phys. (6), 1, 223.

2Hintze, Ann. Chem., 227, 279.

sBaeyer, Ber., 27, 439.

4Hintze, Ann. Chem., 279, 363.

5Wallach, Ann. Chem., 281, 140.

6Wallach, Ann. Chem., 275, 109.

TWallach, Ann. Chem., 252, 124; 270, 175; 245, 268.

96 THE TERPENES.

When dipentene nitrosochloride is warmed with alcoholic pot-
ash, inactive carvoxime,' melting point 93°, is formed.
Benzoyl dipentene nitrosochloride,”

Cl
ae
°” *\NOCOC,H;

is obtained by mixing the solutions of the corresponding active
compounds. It melts at 90°, and is much more readily soluble
than the active modifications.

Dipentene nitrosate, C,,H,,.NO(ONO,), is prepared a adding
three and one-half grams of nitric acid, sp. gr. 1.4, to a well
cooled mixture of five grams of dipentene, four grams ee amyl
nitrite, and two cc. of glacial acetic acid; the resultant nitro-
sate is precipitated by successive additions of alcohol and a little
water. It is recrystallized from benzene, and melts at 84°. It
also yields inactive carvoxime when treated with alcoholic potash
(Wallach *).

DIPENTENE NITROLAMINES.

The dipentene nitrolamines, like limonene nitrolamines, exist in
two isomeric modifications, and are prepared from dipentene ni-
trosochloride, or by mixing the solutions of equal weights of the
corresponding dextro- and levo-limonene nitrolamines (Wallach *).

a-Dipentene nitrolpiperidide,

NO

CoH,

separates almost immediately when the petroleum ether solutions —

of the corresponding active bases, melting at 93° to 94°, are
mixed. It crystallizes from alcohol in monoclinic crystals, which
melt at 154°. |
« B-Dipentene nitrolpiperidide is similarly formed from the limo-
nene bases, melting at 110°; it is more readily soluble than the
a-dipentene nitrolpiperidide, and melts at 152°.
a-Dipentene nitrolanilide,
NO

C,H
10 ae NHC,H,
results by the union of the limonene bases, melting point 112°
to 113°. It melts at 125° to 126°.

1Wallach, Ann. Chem., 245, 268.
2Wallach, Ann. Chem., 270, 177.
3Wallach, Ann. Chem., 245, 270.
4Wallach, Ann. Chem., 252, 123; 270, 180.

HYDROCHLORODIPENTENE NITROLANILIDE. 97

f-Dipentene nitrolanilide is prepared from the limonene bases,
melting at 159°. It melts at 149°.
Nitroso-dipentene-a-nitrolanilide,

NO
C,H
*\N(.NO)C,H,

is more difficultly soluble than the corresponding limonene deriva-
tive. It melts at 147° with decomposition.
Nitroso-dipentene-f-nitrolanilide is very easily soluble, and melts
at 129°.
a-Dipentene nitrolbenzylamine,

NO
ie: we
'\NHCH, C,H,

is distinguished from its active components, melting at 92° to
93°, by its superior power of crystallization. The base is ob-
tained from dilute alcohol in monoclinic crystals, melting at 109°
to 110°.

The compounds, C,,H,,CINO(NHC,H,), melting at 78° and
resulting by the addition of hydrochloric acid to dextro- and
levo-8-limonene nitrolanilide in a methyl alcohol solution, com-
bine and yield a substance,’ which belongs to the dipentene series
and melts at 90°.

As has already been mentioned, hydrochlorodipentene nitroso-
chloride and hydrochlorodipentene nitrosate are contained, to-
gether with the corresponding active modifications, in the most
insoluble parts of the compounds described as hydrochlorolimo-
nene nitrosochloride and nitrosate. (See page 82.) Accordingly,
the hydrochlorodipentene nitrolamines are obtained either from
these difficultly soluble portions of hydrochlorodipentene nitrosate
and thus result as by-products during the preparation of the cor-
responding active modifications, or they are prepared by mixing
the active components.

Hydrochlorodipentene nitrolanilide,’

NO
CoH
NHC,H;

is almost insoluble in cold alcohol, and meltsat 140° to 141°.
By the action of alcoholic potash on this amine, two bases con-
taining no chlorine are obtained ; one melts at 123° to 124° and
yields a difficultly soluble hydrochloric acid salt, while the other
1Wallach, Ann. Chem., 270, 188.
*Wallach, Ann. Chem., 270, 195; 245, 262.
7 :

98 THE TERPENES. .

melts at 158° and forms an easily soluble salt. According to Wal-
lach, both bases closely resemble the a- and f-dipentene nitrolani-
lides, but whether they are identical with the latter compounds
has not yet been determined.

Hydrochlorodipentene nitrolbenzylamine,! -

CyB gC
NHCH,C,H,

is almost insoluble in cold alcohol and is sparingly soluble in all
other solvents. It melts at 150°.
Hydrochlorodipentene nitrol-p-tol uidide,

+

Cy CK
NHC,H,CH,

was represented by Wallach? as a limonene compound, but it has
been proved by further investigation to belong to the dipentene
series. It crystallizes with alcohol of crystallization, and melts
at 135°. It is precipitated from its solution in benzene by
petroleum ether as a white mass, which melts at 145° to 146°.

Two compounds should be mentioned which Wallach obtained
by the action of dimethyl aniline and ethyl or methyl alcohol on a
substance called “ hydrochlorolimonene nitrosate ” ; this substance
consists to some extent of hydrochlorodipentene nitrosate.*
According to Wallach, dimethyl aniline acts only in the elimina-
tion of hydrochloric acid, while the ONO,-group appears to be
replaced by the ethoxyl- or methoxyl-group.

The compound,

NO
C,sH,.NO,Cl = CyHn Ol
H,

forms splendid crystals, which melt at 114° to 115°.
The compound,
NO
C,,H»pNO,Cl = Cy, C1C
OCH.

crystallizes in prisms, melting at 139°.
A condensation-product,* C,,H,,O, is formed by heating an aleo-
holic solution of dipentene and paraformaldehyde in a sealed tube

1Wallach, Ann. Chem., 270, 193.
2Wallach, Ann. Chem., 245, 263.
sWallach, Ann. Chem., 245, 265.
40. Kriewitz, Ber., 32, 57.

SYLVESTRENE. 99

at 190° to 195°, for several hours ; it boils at 242° to 248°, and
has the specific gravity 0.9459 at 20°. Its acetyl derivative boils
at 258° to 261°.

The following table presents a convenient synopsis of the most
important derivatives of limonene and dipentene, and of the re-
lations of these substances to oxygenated compounds of the ter-
pene series.

5. SYLVESTRENE.

Sylvestrene was discovered by Atterberg' in Swedish turpen-
tine oil; Wallach? confirmed this observation, and at the same
time found sylvestrene to occur in Russian turpentine oil. Aschan
and Hjelt* further recognized it in the products of the distillation
of pine roots, and Bertram and Walbaum * detected it in the pine
needle oils from Pinus montana and Pinus silvestris.

For the preparation of sylvestrene, the fraction boiling at 174°
to 178° of Swedish oil of turpentine isemployed. This is diluted
with an equal volume of ether, saturated with hydrochloric acid
gas and, after one to two days standing, the ether is distilled off,
and the residue allowed to crystallize in an extremely cold
place.

The preparation of this compound is attended with the best re-
sults only in winter. The crude sylvestrene dihydrochloride,
which is very soluble in the mother-liquor, is filtered by the
pump, pressed on a porous plate, and dissolved in an equal weight
of alcohol, in order to remove the admixed dipentene dihydro-
chloride. It crystallizes from the very cold, alcoholic solution,
and is recrystallized from ether until it melts at 72°. The
mother-liquors contain a mixture of sylvestrene- and dipentene-
dihydrochlorides (Wallach °).

Pure sylvestrene is obtained by heating the dihydrochloride
with an equal weight of aniline’ and a small quantity of alcohol
(Atterberg’), or better by boiling with the same weight of fused
sodium acetate and twice its weight of glacial acetic acid for half
an hour in a flask fitted with an upright condenser.’ The hydro-
carbon is distilled with steam, heated with a potassium hydroxide
solution, again distilled with steam, and fractionated.

1Atterberg, Ber., 10, 1202.

2Wallach, Ann. Chem., 230, 240 and 247.
8Aschan and Hjelt, Chem. Ztg., 18, 1566.
4Bertram and Walbaum, Arch. Pharm., 231, 290.
5Wallach, Ann. Chem., 239, 24.

6Wallach, Ann. Chem., 247, 197.

100

THE TERPENES.

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SYLVESTRENE DIHYDROBROMIDE. 101

_ PrRopEeRTIES.—Sylvestrene has a very agreeable odor, which is
somewhat similar to that of lemons, but for the most part re-
sembles that of the oil of bergamot. It boils at 176° to 177°,
has the sp. gr. of 0.8510 at 16°, and the refractive index,
n, = 1.47468.' Another specimen boiled at 175° to 176°, and
at 20° had the sp. gr. of 0.848 and the refractive index,
np = 1.47573.? Sylvestrene is optically dextrorotatory. The
specimen above referred to had the specific rotatory power,
[4] >= + 66.32°

The addition of a drop of concentrated sulphuric acid (or
fuming sulphuric acid) to a solution of one drop of sylvestrene
in acetic anhydride produces a deep blue coloration. A similar
reaction is shown only by carvestrene ; all other terpenes under
like conditions give a red to yellowish-red coloration. This
sylvestrene reaction, therefore, is produced only by mixtures
of terpenes which contain considerable quantities of sylvestrene
( Wallach’).

Sylvestrene is one of the most stable of the terpenes. On
heating to 250° it is partially polymerized, without a previous
transformation into other terpenes. In a similar manner
alcoholic sulphuric acid appears to merely change it into
resinous products, but also without previous conversion into iso-
merides.

Sylvestrene dihydrochloride, C,,H,,-2HCl.—The formation of
this compound from Swedish turpentine oil has already been sug-
gested. It may further be prepared direct from pure sylvestrene
by saturating the cold, dry hydrocarbon with dry hydrochloric
acid gas, or more conveniently and readily by adding a solution
of hydrochloric acid in glacial acetic acid to a solution of sylves-
trene in glacial acetic acid, and then pouring the liquid into cold
water.’

Sylvestrene dihydrochloride crystallizes in monosymmetric
tablets, which melt at 72° and have a specific rotatory power,
[a]>= + 18.99%.

Sylvestrene dihydrobromide,* C,,H,,.2HBr, is obtained in a
similar manner to the dihydrochloride ; it crystallizes in mono-
clinic crystals, melts at 72°, and possesses the specific rotatory
power,’ [4],= + 17.89°.

Sylvestrene dihydriodide,* C,,H,,.2HI, is prepared like the two

'Wallach and Pulfrich, Ann. Chem., 245, 197.
?Wallach and Conrady, Ann. Chem., 252, 149.
sWallach, Ann. Chem., 239, 27.
‘Wallach, Ann. Chem., 239, 28.

102 THE TERPENES. -

preceding compounds, and crystallizes from petroleum ether in
small plates, which melt at 66° to 67°.

Sylvestrene tetrabromide,’ C,,H,,Br,—This compound can only
be obtained from pure sylvestrene, regenerated from the dihydro-
chloride. Bromine is slowly added to a cold solution of the ter-
pene in glacial acetic acid until a yellow color is produced, and
after the addition of a small quantity of water to the reaction-
mixture, it is allowed to stand in an open vessel in a cold place ;
crystals separate, and are purified by recrystallization from ethyl
acetate or ether. Sylvestrene tetrabromide is so obtained in the
form of monosymmetric crystals, which melt at 135° to 136°,
and are optically dextrorotatory. Wallach and Conrady found
the specific rotatory power, [a] p= + 73.74°.

Considerable amounts of an oily tetrabromide are always
formed, together with the solid compound; this is probably the
reason why sylvestrene can not be separated in the form of its
tetrabromide from mixtures of sylvestrene and other ethereal
oils.

Sylvestrene nitrosochloride, C,,H,,- NOCI, is prepared from
pure sylvestrene, obtained from its dihydrochloride, by the follow-
ing method. Toa well cooled mixture of four ec. of the terpene
and six ce. of amyl nitrite, four cc. or five ec. of fuming hydro-
chloric acid are added with constant agitation. When the heavy oil
which separates is shaken with a little ethyl alcohol, it solidifies
to a crystalline mass. It is purified by dissolving in a small
quantity of chloroform and precipitating with petroleum ether ;
the product is then recrystallized from methyl alcohol. It melts
at 106° to 107°, and is dextrorotatory ( Wallach’).

Sylvestrene nitrolbenzylamine,

NO
CHa :
NHCH,(C,H,

is obtained by warming an alcoholic solution of sylvestrene nitro-
sochloride with benzylamine (Wallach*). The base separates from
methyl! alcohol in well defined crystals, melting at 71° to 72°. It
has a specific rotatory power, [a], = + 185.6°, while that of its
hydrochloride is [¢] p= + 79.2°.4

1Wallach, Ann. Chem., 239, 28.

2Wallach, Ann. Chem., 245, 272.

3Wallach, Ann. Chem., 252, 135.

4Wallach and Conrady, Ann. Chem., 252, 150.

CARVESTRENE. 103

According to Baeyer,' sylvestrene may be converted into meta-
eymene by a method similar to that employed in the conversion of
limonene into para-cymene. Dry sylvestrene dihydrobromide is
brominated by bromine in the presence of iodine, and the resulting
product is reduced with zine dust and alcoholic hydrochloric acid,
and finally with sodium and alcohol ; a hydrocarbon is obtained,
which, when freed from unsaturated compounds by the action of
potassium permanganate, is identical with meta-cymene.

6. CARVESTRENE.

This optically inactive terpene was obtained by Baeyer? in the
distillation of carylamine hydrochloride and vestrylamine hydro-
chloride. Since it has no rotatory power, and yields the sylves-
trene reaction, Baeyer regards it as inactive sylvestrene. Its
similarity with sylvestrene and its formation from a carvone de-
rivative suggested the name carvestrene.

Wallach * obtained dihydrocarvone, C,,H,,O, by the oxidation
of dihydrocarveol ; subsequently, Baeyer* prepared the same com-
pound by the reduction of carvone. Dihydrocarvone is converted
into the isomeric ketone carone, C,,H,,O, by the successive ad-
dition and removal of hydrobromic acid (Baeyer®). When the
oxime of this optically active carone is reduced with sodium and
alcohol, it yields an active base carylamine, which in turn may
be changed into the hydrochloride of an isomeric, but optically
inactive, base, vestrylamine,’ C,,H,,NH,, by heating with hydro-
chloric acid.

When vestrylamine hydrochloride? is distilled in an atmos-
phere of dry hydrochloric acid gas, it decomposes into ammonium
chloride and a hydrocarbon, C,,H,,, whilst carylamine hydrochlo-
ride, under the same conditions, partially volatilizes without change,
but a little of it is converted into vestrylamine hydrochloride,
which then yields the same hydrocarbon ; the latter consists of
crude carvestrene :

C,)H,,NH,-HCl = NH,Cl + C, Hig

The impure carvestrene is boiled for half an hour with fused
sodium acetate and glacial acetate acid in order to destroy ad-

1Baeyer and Villiger, Ber., 31, 2067.
2Baeyer, Ber., 27, 3485.

8Wallach, Ann. Chem., 275, 115; 279, 378.
4Baeyer, Ber., 26, 823.

5Baeyer, Ber., 27, 1919.

104 THE TERPENES.

mixed hydrochlorides. The resultant terpene boils at 180° to
186°, and gives the sylvestrene reaction (the addition of a drop of
concentrated sulphuric acid toa solution of one drop of the terpene
in one or two cc. of acetic anhydride produces a blue coloration).
The product is then dissolved in glacial acetic acid, treated with
an acetic acid solution of hydrogen bromide, and allowed to re-
main at a low temperature for forty-eight hours, since the addi-
tion of hydrobromic acid to carvestrene takes place very slowly.
The reaction-mixture is poured onto ice; the resulting crystals
are filtered, pressed on a plate and purified by recrystallizing from
ether, to which a little glacial acetic acid is added. The dihy-
drobromide is readily soluble in ether, more sparingly in glacial
acetic acid.

Pure carvestrene is formed by distilling the dihydrobromide
with four parts of quinoline, and shaking the distillate with dilute
sulphuric acid ; the terpene remains undissolved, and is rectified
over sodium.

PROPERTIES.'—Carvestrene has an odor somewhat like that of
dipentene ; it boils at 178° (corr.), and is optically inactive.
Baeyer gives no statements relative to its specific gravity. It rap-
idly becomes resinous on exposure to air, and then smells like tur-
pentine oil. It decolorizes potassium permanganate at once, and,
like terpinene, is oxidized by chromic acid in thecold. It has al-
ready been suggested that since carvestrene gives the sylvestrene
reaction, it is perhaps to be regarded as the optically inactive mod-
ification of sylvestrene.

According to Semmler,’ the crude carvestrene, boiling at 180°
to 186°, obtained by the elimination of ammonia from vestry-
lamine, probably contains some pseudo-carvestrene ; while the pure
terpene, boiling at 178°, prepared by heating the dihydrobromide
with quinoline, is to be regarded as the true ortho-carvestrene.

Carvestrene dihydrochloride, C,,H,,-2HCl, is prepared by treat-
ing pure carvestrene (regenerated from the dihydrobromide) in
a glacial acetic solution with hydrogen chloride, and, after stand-
ing for twenty-four hours, pouring the product onto ice. The
heavy oil which separates solidifies on the addition of an ex-
tremely small crystal of the dihydrobromide. It crystallizes from
glacial acetic acid in long prisms, and melts at 52.5°.

Carvestrene dihydrobromide, C,,H,,-2HBr, obtained by the
method given above, crystallizes in well formed, rhombic tablets
whose solid angles are truncated. These crystals may be easily

'Baeyer, Ber., 27, 3490.
2Semmler, Ber., 34, 708.

A ee ee = he et

Ti Vin eS

TERPINOLENE. 105

distinguished from those of the isomeric dipentene dihydrobro-
mide. Carvestrene dihydrobromide melts at 48° to 50°, and is
more readily soluble than dipentene dihydrobromide.

By the action of silver acetate and glacial acetic acid on the dihy-
drobromide, a terpine results, which melts at 127° and crystallizes
in splendid, flat, rhombic pyramids.

Baeyer' has also succeeded in converting carvestrene into meta-
ceymene by the bromination of carvestrene dihydrobromide, and
subsequent reduction with zine and hydrochloric acid, and finally
with sodium and alcohol.

7. TERPINOLENE.

Terpinolene is one of the terpenes which have not yet been

‘found in nature. It was discovered, and characterized as a

chemical individual, by Wallach ? in 1885. He showed that when
turpentine oil is heated with alcoholic sulphuric acid, according
to Flawitzky’s* method, a terpene is formed, which had hitherto
been overlooked. According to further observations* of Wallach,
terpinolene is obtained by boiling terpine hydrate, terpineol or
cineole with dilute sulphuric acid or phosphoric acid. In all these
reactions, terpinene and other products are formed; among the
latter, cymene should be especially noted as it results whenever
the sulphuric acid method is employed. Wallach and Kerkhoff*®
found that solid terpineol (m. p. 35°) is remarkably well ad-
apted for the preparation of terpinolene, and that the formation
of by-products can be prevented by using a solution of oxalic
acid for the removal of the elements of water; however, it is
well to boil for a short time only, since otherwise a conversion
into terpinene results. Terpinolene may also be prepared with
great facility by dissolving terpineol in anhydrous formic acid,
and gently heating the liquid for a few minutes, when terpinolene
separates rapidly.°

According to Baeyer,’ terpinolene is formed from the tribro-
mide, C,,H,,Br, (m. p. 110°), which is derived from dipentene
dihydrobromide by bromination. This tribromide is converted
into the acetate of 4-4(8)-terpen-1-ol, an alcohol melting at 69°

1Baeyer and Villiger, Ber., 3/, 1402.
2Wallach, Ann. Chem., 227, 283; 230, 262.
8Flawitzky, Ber., 12, 1022.

#Wallach, Ann. Chem., 239, 23.

5Wallach and Kerkhoff, Ann. Chem., 275, 106.
6Wallach, Ann. Chem., 291, 342.

TRaeyer, Ber., 27, 436.

106 THE TERPENES.

to 70°, by the action of zine dust and glacial acetic acid, and when

this acetate is distilled with quinoline, terpinolene results :
C,,H,,0COCH, — CH,COOH = C,,Hy,.

Baeyer expresses these transformations by the following formulas:

CH, Hi,
Br OCOCH,
x,
H, (en a
H, HA, _ H, x A;
CBr
Br
H;C CH; H;C CH;
Tribromide (m. p. 110°). A*®)-Terpen-1-ol acetate.
H, A,
\ gi \
H, JL H, JH
H.C. CH, oe Ha CH,
i H
OH
ue
H; CH, H;C CH;
Terpinolene. Terpineol (m. p. 35°).

It is worthy of notice that terpinolene tetrabromide may be
converted into terpinolene by treatment with zinc dust and glacial
acetic acid.

PREPARATION.'—Melted terpineol (m. p. 35°) is added drop
by drop to a boiling solution of oxalic acid (one part of acid to
two parts of water) through which a current of steam is passing.
The addition of the terpineol is so regulated that one gram is
introduced every minute, thus accomplishing the decomposition
almost completely, while the resulting terpinolene is at once re-
moved from the action of the acid by means of the steam distilla-
tion. The oil so obtained is distilled in vacuum, since terpinolene
is partially changed by distillation at ordinary pressure.

A purer product is obtained by treating terpinolene tetrabro-
mide with zine dust and glacial acetic acid at a low temperature.

PROPERTIES.—Terpinolene is an optically inactive hydrocarbon
whose physical constants have not been determined because its in-
stability prevents the preparation of a chemically pure product.

1Wallach and Kerkhoff, Ann. Chem., 275, 106; Baeyer, Ber., 27, 448.

TERPINOLENE TETRABROMIDE. 107

According to Wallach,’ it boils between 185° and 190°.
Baeyer states that terpinolene prepared from the tetrabromide
boils at 75° under 14 mm. pressure ; on distilling under the or-
dinary pressure it boils at 183° to 185° (corr.), but by continued
boiling for ten minutes in a flask connected with reflux condenser,
terpinolene is changed into a thick oil which no longer gives the
crystalline tetrabromide.

It is very sensitive toward acids, being converted into a prod-
uct which consists largely of terpinene.

A solution of terpinolene in glacial acetic acid absorbs hydro-
chloric or hydrobromic acid, producing dipentene dihydrochloride
or dihydrobromide.'

Terpinolene dibromide, C,,H,,Br,.—Baeyer * obtained this com-
pound from terpinolene (regenerated from the tetrabromide by
means of zinc dust) by adding two atoms of bromine to the hydro-
carbon dissolved in a mixture of alcohol and ether. On evapora-
tion of the solution, the dibromide separates in beautiful prisms,
which melt at 69° to 70°.

When the glacial acetic acid solution of terpinolene dibromide
is treated with hydrobromic acid, the same tribromide (1, 4, 8-
tribromoterpane, m. p. 110°) results which Wallach obtained by
the bromination of dipentene dihydrobromide. This tribromide
is further identified by its conversion into the characteristic, blue
nitrosochloride of 4-4- my terpen-l-ol acetate, melting at 82°
(Baeyer ”).

Terpinolene tetrabromide, C,,H,,Br,, was first prepared by Wal-
lach by brominating terpinolene in a glacial acetic acid solution at a
low temperature.* According to Baeyer and Villiger,*‘ it is better
to dilute crude terpinolene in portions of ten grams or less with
an equal volume of amyl alcohol and twice its volume of ether,
and then to add bromine to the well cooled mixture. After evap-
oration of the ether, the tetrabromide crystallizes in voluminous
leaflets.

Optically inactive terpinolene tetrabromide crystallizes from
ether in monoclinic tablets,’ which melt at 116°. It is not a
very stable compound ; after keeping for some time it melts at a
lower temperature, and changes into a porcelain-like mass, which,
on crystallization from ether, yields only partially the pure tetra-
bromide.

1Wallach, Ann. Chem., 239, 23.

2Baeyer, Ber., 27, 447 and 448.

sWaliach, Ann. Chem., 227, 283; 230, 263; 239, 23; 275, 107.
4Baeyer and Villiger, Ber., 27, 448.

5Hintze, Ann. Chem., 230, 263.

108 THE TERPENES.

When it is treated with zinc dust and glacial acetic acid, it is
reverted into terpinolene (Baeyer); alcoholic potash seems to react
less readily (Wallach and Kerkhoff).

8. PHELLANDRENE.

Phellandrene is characterized by its nitrosite, which was dis-
covered by Cahours, and has, therefore, long been recognized as
a constituent of many ethereal oils. The name phellandrene was
introduced by Pesci," who proved the presence of this terpene in
the oil of water fennel (Phellandrium aquaticum). It is also a
constituent of bitter fennel oil in which Cahours? discovered it,
and which later served as the material for investigations regard-
ing phellandrene nitrosite. The occurrence of phellandrene in
these two oils was confirmed by Wallach,* who further showed
that phellandrene occurs in the oil of elemi,* and that these three
oils contain dextro-phellandrene whose nitrosite is levorotatory.
Levo-phellandrene was afterwards discovered by Wallach and
Gildemeister® in eucalyptus oil (Hucalyptus amygdalina) ; its
nitrosite rotates the plane of polarization to the right. Bertram
and Walbaum® found levo-phellandrene in the pine needle oils
from Pinus montana and Picea excelsa, while Power and Kleber’
proved its presence in bay oil. According to Wallach and Rhein-
dorf,® dextro-phellandrene is contained in the distillation-products
of the soft and hard elemi resins. The results of experiments
performed in the laboratory of Schimmel & Co. indicate that
phellandrene is widely distributed, and that it is contained in the
following oils :—andropogon oil, angelica oil, bay oil, peppermint
oil, camphor oil, curcuma oil, oils from sassafras bark and leaves,
ginger oil, star anise oil, pepper oil, dill oil, wormwood oil, golden
rod oil, lemon oil, olibanum oil and cinnamon oil.

Phellandrene is found in the fractions boiling at about 170° of
the above-mentioned oils; a method for the preparation of pure
phellandrene is not at present known. Oils containing this hydro-

1Pesci, Gazz. Chim., 16, 225.

*Cahours, Ann. Chem., 41, 74; compare Bunge, Zeitschr. Chem., 1869, 579;
Chiozza, Gerhardt’s Lehrb., German edition, 3, 394.

*Wallach, Ann. Chem., 239, 40.

*Wallach, Ann. Chem., 246, 233.

’Wallach and Gildemeister, Ann. Chem., 246, 282 and 233.

SBertram and Walbaum, Arch. Pharm., 231, 290.

™Power and Kleber, Pharm. Rundschau, 1895, No. 13; compare Schimmel’s
Semi-Annual Report, April, 1895, 13; see also Pharm. Review, 1896.

8Wallach and Rheindorf, Ann. Chem., 271, 310.

PHELLANDRENE NITROSITE, 109

carbon are fractionated in a vacuum’ since it is partially de-
composed by distillation at ordinary pressure.

PrRoPERTIES.—Phellandrene occurs in two modifications which
are distinguished by opposite rotatory powers, and boils at about
170°. By the distillation of the oil of water fennel, Pesci * obtained
a fraction which contained about eighty per cent. of phellandrene,
boiled at 171° to 172°, had the specific gravity 0.8558 at 10°
and the specific rotatory power, [a] = + 17.64°.

Wallach* found that phellandrene from an Australian euca-
lyptus oil boiled at 65° (12 mm.), had the sp. gr. 0.8465 and re-
fractive index, np = 1.488, at 19°. Gildemeister and Stephan *
found the optical rotation of phellandrene from schinus oil to be
[a],>= + 60° 21’.

It is one of the most unstable of the terpenes. If the fractions
of the oils of fennel which contain phellanderne are saturated with
hydrobromic acid, a violent reaction takes place, and when the
reaction-product is poured into water, a heavy oil separates; this
oil yields dipentene by heating with sodium acetate and glacial
acetic acid. If the same fractions of the fennel oils are warmed
with alcoholic sulphuric acid, the phellandrene is converted into
terpinene (Wallach’®). Although the substances which occur to-
gether with phellandrene in the fennel oils influence to some ex-
tent the character of the products resulting in the above-men-
tioned reactions, nevertheless it is remarkable that in both cases
no trace of phellandrene’ can be detected in the reaction-prod-
ucts.

Phellandrene dibromide’ is an oil, and is probably a mixture.
It yields considerable cymene by boiling with alcoholic potash.

Phellandrene nitrosite,° C,,H,,.N,O,, is prepared by adding a
solution of five grams of sodium nitrite in eight cc. of water to
a solution of five cc. of the fraction of the ethereal oil containing
phellandrene in ten cc. of petroleum ether, and then adding
slowly, with constant stirring, five ce. of glacial acetic acid.
The resulting crystals are filtered, washed with water and methyl
alcohol, and finally purified by dissolving in chloroform and_pre-
cipitating with methyl alcohol. It dissolves easily in ethyl
acetate, and melts at 104° to 105°. Only the perfectly pure sub-
stance can be recrystallized without decomposition, the crude
nitrosite suffering complete decomposition by such treatment.

1Wallach and Herbig, Ann. Chem., 287, 371.

2Pesci, Gazz. Chim., 16, 225; Ber., 19, 874, Ref.

3Gildemeister and Stephan, Arch. Pharm., 235, 591.

4Wallach, Ann. Chem., 287, 383.

5Wallach, Ann. Chem., 239, 43.
6Wallach and Gildemeister, Ann. Chem., 246, 282.

110 THE TERPENES.

Bertram and Walbaum' recommend the purification of this com-
pound by solution in ethyl acetate and precipitation with sixty
per cent. alcohol. For the preparation of large quantities of
phellandrene nitrosite, compare Wallach and Herbig.”

The nitrosite prepared from dextro-phellandrene is optically
levorotatory ; Pesci* found its specific rotatory power, [a], = —
183.50°. The nitrosite of levo-phellandrene is dextrorotatory.
By mixing the solutions of equal quantities of dextro- and levo-
phellandrene nitrosite, an optically inactive modification* is ob-
tained, which is identical in all other properties with the two
active derivatives.

According to a more recent investigation by Schreiner,’ crude
phellandrene nitrosite, prepared from a levorotatory fraction of
an eucalyptus oil containing phellandrene, has the rotatory power,
[4] p= + 28.5°. When the crude nitrosite is rapidly dissolved
in boiling ethyl acetate and then cooled with ice-water, a nitrosite
separates which melts at 120° to 121°, has the rotation, [a],
= + 123.5°, and forms long, well defined needles ; on precipitat-
ing the ethyl acetate mother-liquor with sixty per cent. alcohol, a
second nitrosite is obtained, which melts at 100° to 101°, has the
optical rotation, [a], = — 36°, and crystallizes in confused ag-
gregates. When the lower melting compound is recrystallized
from methyl] alcohol, the melting point is raised to 105° to 106°.
The relationship between these two phellandrene nitrosites has not
yet been explained. Since the highest melting point given by
Wallach and Herbig is 105°, Schreiner concludes that they did
not have the pure phellandrene nitrosite.

A solution of phellandrene nitrosite in chloroform does not
decolorize bromine so that it is regarded as a saturated compound
(Wallach). In other respects it is more unstable than the isomeric
terpinene nitrosite, and unlike the latter it is not converted into
nitrolamines by the action of organic bases. According to Pesci,®
phellandrene nitrosite yields phellandrene diamine, C,,H,,(NH,),,
by reduction with nascent hydrogen, and it is, therefore, to be
considered as having the formula,

NO
NO,

1Bertram and Walbaum, Arch. Pharm., 231, 298.

2Wallach and Herbig, Ann. Chem., 287, 371.

3Pesci, Gazz. Chim., 16, 225; Ber., 19, 874, Ref.

4Wallach, Ann. Chem., 246, 235.

50. Schreiner, Pharm. Arch., 1901, 4, 90; compare Gildemeister and
Stephan, Arch. Pharm., 235, 591; Schimmel & Co., Semi-Annual Report,
October, 1901, 62.

CioHig

"-@

PHELLANDRENE NITROSITE. TT

By the action of ammonia on the nitrosite Pesci obtained a sub-
stance having acid properties, which has the empirical constitution,
C,,H,,N,O, and crystallizes in needles. Nitrophellandrene, C,,-

isNO,, is formed, together with the preceding compound, by
the action of ammonia on the nitrosite ; it is a yellow oil, which is
converted into amidophellandrene, C,,H,,NH,, on reduction.

According to Wallach,’ when pure phellandrene nitrosite is treated
with ammonium hydroxide, sp. gr. 0.93, it is slowly dissolved with
evolution of nitrous oxide; a white solid results, which gives nitro-
phellandrene on heating with water, acids or alkalis. This dis-
agreement with the observations of Pesci is explained by the as-
sumption that Pesci’s nitrosite was not purified sufficiently.

Nitrophellandrene is also formed by adding the nitrosite to acetyl
chloride. ,

When phellandrene nitrosite is oxidized with nitric acid it
yields terephthalic acid, isopropyl succinic acid, and an isomeride
of this acid, C,H,,O,, together with a neutral compound, C,H,,-
O,N,; the latter substance melts at 88° to 89°, and gives the
Liebermann reaction for nitroso-compounds. The acid, C,H,,O,,
melts at 85° to 88°. Isopropyl succinic acid is also produced
when the nitrosite is oxidized with potassium permanganate.

A detailed investigation regarding the constitution of phellan-
drene and its nitrosite was carried out by Wallach and Herbig.’
If phellandrene nitrosite be treated with sodium ethylate, pure
nitrous oxide is evolved, and an oil is formed, which boils in a
vacuum at 134° to 138°; it has the formula, C,,H,,NO,, is
heavier than water, and smells like a quinone. This substance,
which Wallach and Herbig regard as chemically identical, and
physically isomeric with the “nitrophellandrene” obtained by
Pesci, is not a nitro-compound ; if it be reduced with sodium and
alcohol, or even by the direct reduction of phellandrene nitrosite,
the following reaction-products are obtained :

1. Optically active tetrahydrocarveol, C,,H,,OH.

2. Optically active tetrahydrocarvone, C,,H,,O.

3. Optically active tetrahydrocarvylamine, C,,H,,NH,,.

The tetrahydrocarvone thus obtained has a rotatory power op-
posite to that of the phellandrene from which it is derived.

Since optically inactive tetrahydrocarveol is formed by the re-
duction of carvone and carvenone, it follows that phellandrene
must have the same cyclic structure of the carbon atoms as carve-
none, and that it must also have a double linkage on that atom
of carbon which in carvone is attached to an oxygen atom.

1Wallach, Ann. Chem., 313, 345.

*Wallach and Herbig, Ann. Chem., 287, 371.

112 THE TERPENES.

9. TERPINENE.

Terpinene escaped the notice of the earlier investigators because
they assumed that it was identical with dipentene. Wallach,'
however, recognized it as a definite terpene, and Wallach? and
Weber ° distinctly characterized it by its transformation into ter-
pinene nitrosite. Weber? first obtained the nitrosite during an
investigation of cardamom oil. Terpinene occurs in oil of carda-
mom, and this, together with marjoram oil, are the only ethereal
oils in which terpinene has been observed.‘

The methods of preparation of this terpene are based upon a
characteristic property of terpinene, its stability towards dilute
mineral acids. It is formed by boiling dipentene® and phellan-
drene ® with dilute or alcoholic sulphuric acid ; it is also obtained
by boiling terpine hydrate,’ cineole,’ terpineol ® or dihydrocarveol ®
with dilute or alcoholic sulphuric acid. The transformation of
dihydrocarvylamine, C,,H,,NH,, an amine corresponding to the
alcohol, dihydrocarveol, into terpinene is of special interest. By
the dry distillation of dihydrocarvylamine hydrochloride, Wal-
lach ’° obtained terpinene, admixed with para-cymene ; the latter
hydrocarbon is very readily formed by the oxidation of terpinene
(see below). Terpinene is further prepared by heating dihydro-
carvylamine with acid potassium sulphate. The formation of
this terpene by the action of formic acid on linalool” has already
been referred to. ‘Turpentine oil is well adapted for the prepa-
ration of terpinene. A product containing this substance is ob-
tained by agitating oil of turpentine with concentrated sulphuric
acid, care being taken to avoid a rapid increase in temperature ;
hence it forms a constituent of the oil which Armstrong and
Tilden ” formerly designated “ terpilene.”

1Wallach, Ann. Chem., 230, 254 and 260.

2Wallach, Ann. Chem., 239, 33.

3Er. Weber, Ann. Chem., 238, 107.

4W. Biltz (Ber., 32, 995), finds that the fractions, boiling at 77° to 81° at
30 mm. pressure, of the crude oil of Origanuwm majorana consist largely of
terpinene, which was identified by the formation of the nitrosite.

5Wallach, Ann. Chem., 239, 15.

6Wallach, Ann. Chem., 239, 43.

TWallach, Ann. Chem., 239, 22.

8Wallach and Kerkhoff, Ann. Chem., 275, 106.

SWallach, Ann. Chem., 275, 113.

10Wallach, Ann. Chem., 275, 125.

uBertram and Walbaum, Journ. pr. Chem. [2], 45, 601.

Warmstrong and Tilden, Ber., 12, 752.

_

TERPINENE. 113

A product especially rich in terpinene is obtained by the fol-
lowing method.

Seventy cc. of concentrated sulphuric acid are added gradually,
in portions of five cc. at atime, to two liters of turpentine oil, con-
tained in a thick-walled vessel. The introduction of the acid is
so regulated that the temperature does not rise so high that the
vessel cannot be conveniently handled, and after every addition
of acid the liquid is well agitated. When all of the sulphuric
acid is added, the mixture is shaken at frequent intervals for a
day, allowed to stand for, one or two days, neutralized with sodium
carbonate or hydroxide, and the product distilled with steam.
The greater part of the resultant oil boils between 170° and 190°,
and may be directly employed for the preparation of terpinene
nitrosite (Wallach *).

PROPERTIES.—Absolutely pure terpinene has not been obtained.
The product prepared by the transformation of pinene, or by
other methods, is obviously not entirely free of isomeric terpenes,
and, moreover, always contains cymene. ‘Terpinene is readily
converted into cymene by the oxidizing influence of sulphuric
acid. (Wallach and Kerkhoff observed the formation of sulphur-
ous acid during the preparation of terpinene from terpineol and
dilute sulphuric acid.) The presence of cymene may have
possibly caused the formation of toluic acid, which Tilden and
Williamson obtained in the oxidation of terpinene with nitric
acid.’

Terpinene boils at 179° to 181°. The product obtained by
boiling dihydrocarveol with dilute sulphuric acid boils at 178°
to 180°, has the specific gravity 0.847 and the refractive index,
n, = 1.48458, at 20°. It smells like cymene, is optically in-
active, and is one of the most stable of the terpenes. If it be
heated with alcoholic sulphuric acid or treated with concen-
trated sulphuric acid, it is partially converted into resin; the
remaining portion, however, forms large quantities of terpinene
* eta and contains no other terpene than terpinene (Wal-
ach*).

i very sensitive towards Beckmann’s chromic acid mixture
(six parts of potassium dichromate or the corresponding quantity
of sodium dichromate, five parts of concentrated sulphuric acid
and thirty parts of water). This reagent easily and quickly de-
composes terpinene, even in the cold, with formation of a brown

1Wallach, Ann. Chem., 239, 35.
*Tilden-and Williamson, Journ. Chem. Soc., 63 (1893), 295.
§Wallach, Ann. Chem., 239, 38.

8.

114 THE TERPENES.

precipitate, but it is without action on other terpenes as pinene,
limonene, camphene and terpinolene, as well as the oxides cineole
and pinole, at ordinary temperature ; therefore, terpinene is very
readily removed from these substances by repeated treatment with
the oxidizing mixture until a brown precipitate-is no longer pro-
duced (Baeyer'’).

According to Semmler,’ terpinene is to be regarded as pseudo-
limonene. He further states that Beckmann’s solution is a char-
acteristic reagent for pseudo-terpenes and terpene alcohols.

Hydrochloric, hydrobromic and hydriodic acids unite with ter-
pinene forming liquid addition-products ; the hydrochloride, how-
ever, solidifies at a very low temperature. Dipentene dihydro-
chloride is always formed together with the hydrochloride, but it
has not been determined whether this is produced from terpinene,
or from small quantities of dipentene which may be present in
the terpinene employed. Terpinene also combines with bromine,
yielding an oily dibromide (Wallach *).

Terpinene nitrosite,

NO
CyoH,
NO

The identification of terpinene in an oil is effected quickly and
without any considerable loss of material by diluting two or
three grams of the fraction having the boiling point of terpinene
with petroleum ether, adding a solution of two or three grams of
sodium nitrite, and treating this mixture carefully and with con-
stant agitation with the necessary quantity of acid. The vessel
containing the mixture is held in warm water for a moment, and
then allowed to remain in a cold place. Terpinene nitrosite,
which is insoluble in petroleum ether, separates after standing
for a few hours, or certainly in the course of two days (Wal-
lach *).

Large quantities of terpinene nitrosite are prepared as follows.
To a mixture of 250 grams of terpinene, obtained by the in-
version of pinene by the above-described method, 110 grams of
glacial acetic acid, and forty-four grams of water, a concentrated
aqueous solution of 125 grams of sodium nitrite is added in
small portions at a time and with constant shaking. About two
hours should be allowed for the addition of the sodium nitrite solu-
tion. The separation of crystals commences in a short time and

1Baeyer, Ber., 27, 815.
2Semmler, Ber., 34, 708.
3Wallach, Ann. Chem., 239, 38.

TERPINENE NITROSITE. 115

is nearly complete in the course of two days. The crystals are
filtered, washed with water and then with cold alcohol, and finally
pressed on a porous plate. ‘The nitrosite is purified by dissolving
in glacial acetic acid, reprecipitating with water, and recrystalliz-
ing from hot alcohol (Wallach *).

Terpinene nitrosite’ is very easily soluble in warm alcohol,
ether and ethyl acetate, difficultly in petroleum ether, and sepa-
rates from alcohol in snow-white, monoclinic” crystals, which melt
at 155°. Its solutions are optically inactive.

According to Wallach,‘ its solutions do not decolorize bromine,
so that it behaves as a saturated compound ; more recent investi-.
gations by Semmler® indicate that the nitrosite combines directly
with bromine in glacial acetic acid solution forming a number of
compounds, one of which is crystalline and melts at 102°.

It dissolves readily without decomposition in strong acids and
may be reprecipitated with water; but it is decomposed by con-
tinued boiling with concentrated alkalis. It is decomposed by
concentrated sulphuric acid only on heating to a high tempera-
ture; it does not give the nitroso-reaction when treated with
phenol and sulphuric acid. It may be recrystallized without de-
composition from boiling, concentrated hydrochloric acid.

When terpinene nitrosite is warmed with alcoholic potash,
nitrous fumes are given off, and on immediately pouring the re-
action-product into water, terpinene oxide oxime,’ C,,H,,O: NOH,
separates as a white mass; it melts at 85°, decomposes on dis-
tillation under reduced pressure, and is converted into a liquid
isomeride when dried in a vacuum; it may be kept unchanged
in the air. When the oxime is reduced with sodium and alco-
hol, it yields a base, C,,H,,O-NH,, boiling at 140° to 150° (20
mm.).

By the reduction of terpinene nitrosite with sodium and
alcohol, the following compounds have been obtained.

1. The base,* C,,H,,.NH,. It boils at 209° to 210°, has a sp.
gr. 0.8725, and n, = 1.4717 at 20° ; its carbamide melts at 171°.
It may be converted into an alcohol, which, in turn, yields a
ketone, the oxime of which melts at 96° to 98°.

2. A crystalline base,* melting at 88°.

3. p-Cymene.*

4. A hydrocarbon,’ C,H,,, boiling at 160° to 164°.

When terpinene nitrosite is reduced in an alcoholic solution

'Wallach, Ann. Chem., 239, 35.
2Hintze, Ann. Chem., 241, 315.
3Semmler, Ber., 34, 708.
4Wallach, Ann. Chem., 313, 345.

116 THE TERPENES,

with stannous chloride, it yields a basic compound whose odor is
similar to that of naphthylamine (Wallach).
Two formulas have been suggested for terpinene nitrosite :

ie IL.
N=O JN —O—H
CB N=o and CyoHj; nieto

Brihl’ and Semmler? favor the second formula, which repre-
sents the nitrosite as an isonitroso-compound. Wallach,* however,
in consideration of the insolubility of the compound in alkalis, is
inclined to regard formula I. as the more probable, although he
assumes the existence of the isonitroso-group in the terpinene nitro-
lamines (terpinene nitrolethylamine is soluble in alkalis). What-
ever the constitution of terpinene nitrosite may be, it is converted
under certain conditions into compounds which undoubtedly con-
tain the isonitroso-group.

Terpinene benzoyl isonitrosite,*

ZNO(COC Hs)
C,H 4

10*° 15
ONO

is formed when terpinene nitrosite (thirty grams) is allowed to
stand with dry ether (300 grams) and benzoyl chloride (twenty
grams) for some days. The nitrosite is gradually dissolved,
and on spontaneous evaporation of the ether the benzoyl com-
pound separates. It is recrystallized from alcohol, and melts at
77° to 78°.

TERPINENE NITROLAMINES.

Terpinene nitrosite, like the nitrosochlorides of other terpenes,
is readily converted into nitrolamines. Thus it reacts with am-
monia according to the equation :

JNOH
C,,H,,NO.ONO NH; = CoH; NH a HNO,

This transformation is most readily accomplished with aliphatic
amines ; aromatic bases do not form terpinene nitrolamines, prob-
ably because of a secondary formation of diazo-compounds due

1Briihl, Ber., 21, 175.
*Semmler, Ber., 34, 713.
3Wallach, Ann. Chem., 245, 274.

a

ste an Te ee

TERPINES NITROLDIMETHYLAMINE. 117

to the action of the free nitrous acid, and the reaction-product is
completely decomposed.
Terpinene nitrolamine,'
NOH
Oth K
NH,

is prepared by the following method. Ten cc. of concentrated
ammonia are added in small portions at a time to a hot solution
of five grams of terpinene nitrosite in twenty cc. of ninety-five
per cent. alcohol. When the reaction is complete, forty or fifty
ec. of water are added, and the alcohol and ammonia boiled off.
The solution of the amine is now filtered from a red, resinous im-
purity, and, after the addition of a few drops of ammonia to the
filtrate, terpinene nitrolamine crystallizes in a fairly pure condi-
tion. The mother-liquor is concentrated in vacuum, and yields
further quantities of the nitrolamine. The yield is about ten per
cent. It crystallizes from hot water, decomposes very easily,
and melts at 118°. Werner’ obtained the dibenzoyl derivative
of this base by the Baumann-Schotten method ; it melts at 146°.

For the preparation of substituted terpinene nitrolamines,
Wallach” employs the following method. Terpinene nitrosite is
covered with four times its weight of alcohol, and heated in a
flask with upright condenser until all is dissolved ; two molecular
proportions of the aliphatic amine are then added to the warm
liquid, and, after the completion of the reaction which usually
takes place immediately, the mixture is boiled. The resulting
base is separated by pouring the reaction-product into water ;
after standing for some time it forms a solid mass, which is
washed with water, dissolved in hydrochloric acid, filtered off
from resinous substances, and is precipitated by ammonia. The
nitrolamine so purified is obtained as a semi-solid mass, which,
however, gradually becomes solid and crystalline. It is recrys-
tallized from alcohol.

Terpinene nitrolmethylamine,
JNOH

C,H.
10 ‘Ke HCH,
crystallizes in splendid prisms, which melt at 141°.
’ Terpinene nitroldimethylamine,
NOH
Out Z =
N(CH;).

1 Wallach, Ann. Chem., 241, 320; Werner, Inaug. Diss., Bonn, 1890.
? Wallach, Ann. Chem., 241, 316.

118 . THE TERPENES.

is easily soluble in chloroform, sparingly in alcohol, and melts at

160° to 161°.
Terpinene nitrolethylamine,

NOH
coHZ

H
©” *\NHC,H;

is sparingly soluble in hot water, more readily in warm dilute
sodium hydroxide, and very readily in boiling alcohol, ether and
chloroform. It melts at 130° to 131°, and is decomposed into
hydroxylamine and other products by boiling with hydrochloric
acid. Its nitroso-derivative crystallizes from alcohol in needles,
and melts at 132° to 133°.
Terpinene nitroldiethylamine,
re JNOH
©" NN(CiHs)s
melts at 117° to 118°.
Terpinene nitrolamylamine,
NOH

ClO

is characterized by its splendid power of crystallization. It dis-
solves sparingly in alcohol and ether, and melts at 118° to 119°.
Terpinene nitrolpiperidide,
pats JNOH
10 "\NC Hyg

is quite insoluble in sodium hydroxide; it forms splendid crystals,
which melt at 153° to 154°.
Terpinene nitrolbenzylamine,'
NOH
NHCH,(,H,

is prepared by warming five grams of terpinene nitrosite with
five and one-half grams of benzylamine and ten grams of alcohol.
The crude product is purified by dissolving in acetic acid and
precipitating the filtered solution with ammonia. It crystallizes
from alcohol in fragile, brilliant leaflets, and melts at 137°.

10. THUJENE (TANACETENE).

Thujene appears to be different from all the terpenes which
have been mentioned in the preceding, but the information re-
garding this compound is very incomplete. It is formed in the
dry distillation of thujylamine hydrochloride and isothujylamine
hydrochloride.

1 Wallach, Ann. Chem., 252, 134.

ste

PO ee, See Oa ee

—

- $4

TERPENE FROM INDIAN HEMP. 119

According to Semmler,’ tanacetene boils at 60° to 63° under
14 mm. pressure, has the sp. gr. 0.8508 and refractive index,
ny = 1.476, at 20°. It contains two ethylene linkages.

According to Wallach,’ thujene boils at 170° to 172°, has the
sp. gr. 0.836 and refractive power, ny = 1.47145, at 22°.

In a more recent publication, Tschugaeff* states that thujyl
alcohol, C,,H,,OH, may be converted into a methyl xanthate, and
that when this compound is dry distilled it yields a new terpene,
C,,H,,; the latter boils at 151° to 152.5°, has a sp. gr. 0.8275 at
20°/4°, and the refractive index, np) = if: 45042, at 20°; the
molecular refraction is 44.21, while the calculated value for a
dicyclic terpene is 43.54. It does not form a crystalline nitroso-
chloride, does not form an additive compound with bromine, but
instantly decolorizes permanganate solution ; in the air it is rap-
idly oxidized to a resin. It forms a erystalline compound with
hot mercuric acetate solution.

Tschugaeff regards this new terpene as belonging to the true
thujone series and designates it as ‘‘thujene.” The terpene above
mentioned under the name thujene or tanacetene is considered as
a derivative of isothujone and is therefore called “ isothujene”
(Tschugaeff).

Pie the dry distillation of trimethyl thujylammonium hydroxide,

H,,N(CH,),-OH, Tschugaeff* obtained a thujene which boils
. "151° to 153°, has a sp. gr. 0.8263 at 20°/4°, refractive index,
np = 1.45022, at 20°, and a rotatory power, [a],= — 8.28°.
Since this rotatory power is much greater than that of the thujene
obtained from thujyl alcohol as above described, it is perhaps pos-
sible that thujone, C,,H,,O, gives rise to two stereoisomerie thujyl
alcohols, C,,H,,OH, on “reduction, and these yield two stereo-
isomeric thujenes.

A dextrorotatory thujene* (>= = + 21.83° in a ten ecm.
tube) has been obtained from the last fraction formed in the dis-
tillation of methyl thujylxanthate.

11. TERPENE FROM THE RESIN OF INDIAN HEMP.

A terpene, which appears to be different from those previously
described, is found in the distillate, boiling from 160° to 180°, of
the resin of Indian hemp.’ It has the composition, C,,H,,, boils

1Semmler, Ber., 25, 3345.

2Wallach, Ann. Chem., 286, 97.

3Tschugaeff, Ber., 33, 3118.

4Tschugaeff, Ber., 34, 2276.

5Wood, Spivey, and Easterfield, Journ. Chem. Soc., 69, 541.

120 THE TERPENES.

at 170° to 175°, and has the specific gravity 0.819 at 17°; it is
slightly levorotatory. It has a pleasant odor, and resinifies very
rapidly on exposure to the air. It combines with hydrogen chlo-
ride, forming an oily monohydrochloride.

12. SYNTHETICAL TERPENE.

A terpene, C,,H,,, which may possibly prove to be the first
representative of the class of ortho-terpenes, was obtained by
Wailach* during his investigation of synthetical (ortho-?) pule-
gone, C,,H,,0.

By reducing synthetical pulegone with sodium and alcohol,
pulegol, C,,H,,OH, is formed. When pulegol is heated with
phosphoric anhydride, and the reaction-product is distilled with
steam, the above-mentioned terpene is produced. Its odor re-
sembles that of limonene and of terpinolene; it boils at 173° to
175°, has the specific gravity 0.823 and refractive index, np =
1.4601, at 18°. Further investigations may show some changes
in these physical constants, since the terpene has not been pre-
pared in an absolutely pure condition.

138. FENCHELENE.

This terpene? is produced as a by-product in the formation of
fencholenyl alcohol, C,,H,,OH. It boils at 66° to 70° under 20
mm. pressure, and at 175° to 178° under 760 mm. pressure. It

has the specific gravity 0.842, and the index of refraction, np =

1.47439, at 20°. .
14. EUTERPENE.

This terpene* is formed when dihydroeucarveol, C,,H,,OH,
is treated with phosphorus pentachloride, and the resulting chlo-
ride, after removal of the phosphorus oxychloride, is boiled with
quinoline for thirty minutes. It boils at 161° to165°. It yields
acetic, oxalic, and gem-dimethylsuccinic acids, when it is oxidized
with permanganate.

Euterpene forms a dihydrobromide, which, when acted upon
by bromine in the presence of iodine and then is reduced with zine
and alcoholic hydrochloric acid and finally with sodium and
alcohol, yields 7.2.4-dimethyl-ethyl-benzene, boiling at 185° to
191°.

1Wallach, Ber., 29, 2957.
2Wallach, Ann. Chem., 300, 294.
3Baeyer and Villiger, Ber., 31, 2067.

SABINENE GLYCOL. ey ie

15. TRICYCLENE.

This hydrocarbon was obtained by Wagner’ by treating pinene
dibromide, C,,H,,Br, (m. p. 169° to 170°), with zine dust and
acetic acid. It has the composition, C,,H,,, melts at 65° to 66°,
and boils at 153°; it is indifferent towards potassium permanga-
nate. It forms a solid addition-product with hydrogen chloride.

16. BORNYLENE.

When pinene hydriodide is heated with forty per cent. alcoholic
potash in an autoclave at 170° for four hours, a mixture of
camphene and another hydrocarbon is produced. This mixture
is fractionally distilled, and the fraction boiling at 152° to 160°
is heated with acetic acid in a sealed tube at 55° to 60°; the
camphene is thus converted into isobornyl acetate, while the
other hydrocarbon remains unchanged and is separated by frac-
tionation. This hydrocarbon, C,,H,,, which Wagner?’ calls
bornylene, melts at 97.5° to 98°, boils at 149° to 150° under
750 mm. pressure, and sublimes readily at the ordinary tempera-
ture. It is oxidized at the ordinary temperature by a dilute solu-
tion of potassium permanganate yielding camphoric acid. Wagner
regards it as the hydrocarbon corresponding to camphor and
borneol, and suggests the name bornylene to show this relation ;
for camphene, which may be readily converted into isoborneol,
he proposes the name isobornylene.

17. SABINENE.

The fraction of oil of savin which distills below 195° consti-
tutes about thirty per cent. of the crude oil, and consists mainly
of terpenes. On redistillation of this fraction, an oil is obtained
which boils between 162° and 170°, and consists principally of a
terpene, C,,H,,, which Semmler® calls sabinene.

It has a specific gravity 0.840, a refractive index, up = 1.466,
and a molecular refraction, M='44.9. It forms a liquid di-
bromide, having the specific gravity 1.50, but yields no definite
compound with nitrous acid. It is regarded as a pseudo-terpene.

Sabinene glycol, C,,H,,(OH),, results on the oxidation of sabi-
nene with ice-cold, aqueous potassium permanganate ; it boils at
148° to 150° under 15 mm. pressure, crystallizes from water, and

1Godlewski and G. Wagner, Chem. Centr., 1897 (I.), 1055; Journ. Russ,
Chem. Soc., 29, 121.

#G. Wagner and Brykner, Ber., 33, 2121.

8¥. Semmler, Ber., 33, 1455; 34, 708.

122 THE TERPENES.

melts at 54°. It has the specific gravity, 1.021, the refractive
index, 4p = 1.402, and a molecular refraction, M = 47.41.

Dihydrocuminyl alcohol, C,,H,,OH, is produced by warming
the glycol with acidified water; it boils at 242°, has a sp. gr.
0.9572, up = 1.5018, and M= 46.80. Chromic acid oxidizes it
to cuminy! alcohol and cumin aldehyde.

Sabinenic acid, C,,H,,O,, is formed together with sabinene gly-
col; it is an oxy-acid, crystallizes from water, melts at 57°, and
forms a sparingly soluble, crystalline sodium salt.

When this acid is distilled in vacuum, it loses water and hydro-
gen, and yields cumic acid, C,,H,,O, (m. p. 117° to 118°).

Sabinene, sabinene glycol and sabinenic acid are all dextro-
rotatory.

Sabinene ketone, C,H,,O, is obtained on the oxidation of sabi-
nenic acid with lead peroxide ; it boils at 213°, has a specific gravity
0.945, a refractive index, 4, = 1.4629, and a molecular refrac-
tion, M = 40.26. Its semicarbazone crystallizes from alcohol, and
melts at 135° to137°. The ketone is levorotatory, [a], = — 18°
in a ten cm. tube.

In conclusion, the most important transformations of the several
terpenes into each other are briefly presented in the following
table :

TRANSFORMATIONS IN THE TERPENE SERIES.

Pinene Dipentene ——>Terpinene =—~ Terpinolene
[Limonene] 4 K
Camphene y
A
Terpine
CioHjs(OH),
|
Borneo] Terpineol =——
C,,H,,OH C,,H,,OH
\
Camphor Pinole Cineole

C,)H,,0 Cy, H,,0 C,)H,,0

——e——

HYDROCARBONS, C,,H,,.
1, DIHYDROCAMPHENE, ©,,H,,.

Baeyer' seems to have first prepared this hydrocarbon by the
_ action of zinc dust and glacial acetic acid at a low temperature on
pinene hydriodide and on borny] iodide, C,,H_I.

Bredt and v. Rosenberg? obtained dihydrocamphene by the
reduction of pinene hydrochloride and of bornyl chloride with
sodium and alcohol.

Armstrong * speaks of dihydrocamphene under the term camp-
hydrene, and he mentions its preparation from pinene hydrochloride
by the action of sodium.

Semmler* has also recently prepared this hydrocarbon by the
reduction of pinene hydrochloride, pinene dibromide, camphene
hydrochloride, and camphene dibromide with sodium and alcohol.

Dihydrocamphene® is a saturated hydrocarbon, and may be
freed from impurities by treatment with fuming nitric acid. It
melts at 155.3°, and boils at 159.5°. According to Semmler, it
separates from alcohol in crystals belonging to the hexagonal
system, melts at 155°, and boils at 160° to 162° (uncorr.).

Aschan® describes 4 compound, C,,H,,, which is probably di-
hydrocamphene, under the name camphane. He obtains it by
the reduction of a nearly inactive pinene hydriodide in an acetic
acid solution by means of zinc and hydriodic acid; the product,
an inactive camphane (dihydrocamphene), crystallizes in six-sided
plates, and melts at 153° to 154°.

This saturated hydrocarbon, C,,H,,, is also called camphane by
Forster’ in a paper entitled, “Studies in the Camphane Series ”;
thus, the compound C,,H,,BrNO,, which is obtained from cam-
phoroxime, is called bromonitrocamphane, and the compound,
C,,H,,NO,, nitrocamphane, ete.

It may be mentioned that a hydrocarbon, C,,H,,, termed dihy-
drodicamphene,® is formed by the action of metallic sodium upon
molten pinene hydrochloride. It is a solid, melting at 75° and
boiling at 326° to 327°. :

1Baeyer, Ber., 26, 826.

2Private communication to Dr. Heusler.
3Armstrong, Journ. Chem. Soc., 69 (1896), 1398.
4¥. Semmler, Ber., 33, 774 and 3420.

5Bredt and v. Rosenberg.

60. Aschan, Ber., 33, 1006.

™M. O. Forster, Journ. Chem. Soe., 77 (1900), 251.
8Etard and Meker, Compt. rend., 126, 526.

123

124 THE TERPENES.

2. ISODIHYDROCAMPHENE, C,H...

According to Semmler,' when isoborneol is heated with zine
dust for thirty minutes at 220°, it is converted. into a mixture of
a small quantity of camphene and a much larger amount of a
hydrocarbon, C,, H,,; the latter compound is designated as isodi-
hydrocamphene. It crystallizes from alcohol in fern-like aggre-
gates, which belong to the isometric system. It melts at 85° and
boils at 162° (uncorr.).

While the dihydrocamphenes may be termed the parent-sub-
stances of the terpenes, pinene and camphene, as well as of cam-
phor, the following hydrocarbons, carvomenthene and menthene,
are to be regarded as tetrahydrocymenes.

8, CARVOMENTHENE, C,,H,,.

By the separation of the elements of water from carvomenthol
(tetrahydrocarveol), C,,H,,OH, it may be converted into a hydro-
carbon, C,,H,,, which differs from menthene, C,,H,,, obtained
from menthol in an analogous manner. Therefore, the constitu-
tion of carvomenthene and of menthene can not be expressed by
formula I., according to which both compounds must be identical,
but should rather be regarded as corresponding to formulas II.
and ITI. (Baeyer).

Hi, iN Hi,
H H H
* | 4%
sag H,C H, H, i
I.
H, H.C CHOH H, H
H H
H H H
H; CH, H;C CH; H,C uz,
Carvomenthol Menthol.
({tetrahydrocarveol ).
es Hy;
H
/\
we 2 H U Sy ras H,
. III.
H,C Hy, H, HH
‘H
H H
Ye
H,C CHy H;C CH,
Carvomenthene. Menthene.

tf. Semmler, Ber., 33, 774.

CARVOMENTHENE HYDROBROMIDE. 125

Baeyer ' prepared carvomenthene by treating tetrahydrocarveol

(carvomenthol) with hydrobromic acid, and distilling the result-
ant bromide with quinoline, while Wallach? obtained it by heat-
ing tetrahydrocarveol with acid potassium sulphate for one hour
at 200°. When purified in the usual manner, it boils at 175°
to 176° sonia
_ According to more recent investigations by Kondakoff and
Lutschinin,? carvomenthene is formed by heating carvomenthyl
chloride or bromide with alcoholic potash ; on fractional distilla-
tion, the resultant hydrocarbon may be separated into two por-
tions, about ninety per cent. of the whole boiling at 172° to
174.5°, and the remainder at 174.5° to 178°.

Properties.—The fraction of carvomenthene of the lower boil-
ing point has the specific gravity 0.8230 at 16.3°/4°, a refractive
index, np, = 1.45979, a molecular refraction, M=45.68, and a
specific rotation, [¢],—=— 2° 4’. The higher boiling fraction
has the sp. gr. of 0.8230 at 19°/4°, an index of refraction,
np = 1.46108, a molecular refraction, MJ = 45.89, and a specific
rotatory power, [a], = — 1° 28’.

Carvomenthene is a colorless, mobile liquid having an odor of
menthene ; it is changed on exposure to air, is readily oxidized
by permanganate, and unites with two atoms of bromine, form-
ing an oily bromide. According to Baeyer, it combines with hy-
drogen bromide or iodide in the cold, yielding tertiary carvo-
menthyl halogen derivatives, which may be converted into a
mixture of carvomenthene and tertiary carvomenthol. (See ter-
tiary carvomenthol.)

Carvomenthene hydrochloride, C,,H,,-HCl, boils at 90° to 98°
under 18 mm. pressure, and at 89° to 95° under 16 mm. It
has a specific gravity 0.9390 at 19°/4°, a refractive index
Dy = 1.464941, a molecular refraction, M = 50.95, and a specific
rotatory power, [~] p= — 1° 22’. Its properties are identical with
those of carvomenthyl! chloride, with the one exception of its rota-
tory power (Kondakoff and Lutschinin).

Carvomenthene hydrobromide, C,,H,,HBr, may be obtained by
heating carvomenthene with concentrated hydrobromic acid at
160° to 170°; it boils at 92° to 98° under 10 mm. pressure, has
a specific gravity 1.1620 at 20.5°/4°, a refractive index, np =
1.48822, at 20.5°, a molecular refraction, M = 54.27, and it is
optically inactive. Its properties are almost identical with those
of carvomenthy| bromide, but it seems probable that it consists of

1Baeyer, Ber., 26, 824.

2Wallach, Ann. Chem., 277, 130.
8Kondakoff and Lutschinin, Journ. pr. Chem., 60 (II.), 257.

126 THE TERPENES.

a mixture of secondary and tertiary bromine derivatives, which
are derived from two isomeric carvomenthenes present in the
parent hydrocarbon.

The carvomenthene regenerated from the hydrobromide boils at
172° to 175°, has the specific gravity 0.8230, at 20°/4°, a re-
fractive index, n, = 1.45959, a molecular refraction, 1 = 45.69,
and a specific rotatory power, [a], = — 0° 23’ (Kondakoff and
Lutschinin).

4, MENTHENE, C,,H,,.

The structural formula of menthene has already been referred
to. This hydrocarbon is prepared from menthol by a method
analogous to that used in the preparation of carvomenthene from
tetrahydrocarveol. In the year 1838 Walter obtained men-
thene by treating menthol with vitreous phosphoric acid.

According to Briihl,’ it is prepared by boiling menthol with
fused zine chloride or anhydrous copper sulphate, while Sicker
and Kremers * obtain it by heating menthol with twice its weight
of acid potassium sulphate at 180° to 200°. For its preparation,
Wagner*® recommends the method that Wallach gives for the
preparation of camphene from borneol ; thus, menthol is converted
into menthyl chloride, C,,H,,Cl, by treatment with phosphorus
pentachloride, and this is boiled with aniline for a long time ; the
yield of menthene is almost theoretical. According to Berken-
heim,* menthene is formed as a by-product in the preparation of
menthyl chloride (b. p. 210°) from menthol and phosphoric
chloride ; it is also produced by heating menthyl chloride with
potassium acetate and glacial acetic acid at a high temperature.

Menthyl chloride, prepared from 1-menthol, may be converted
into menthene’ by heating with a solution of potassium phenolate
for twelve minutes at 150°. Menthol may be directly converted
into menthene® by heating with dilute sulphuric acid (one part acid
to two parts water) at 60° to 100°, for six to eight hours; the
yield is said to be 90 per cent. of the theoretical.

According to Tschugaeff,’ a menthene of very high rotatory
power is obtained by the distillation of the methyl ester of men-
thylzanthogenic acid; the latter compound is produced by treat-

1Briihl, Ber., 25, 142.

2Sicker and Kremers, Ammer. Chem. Journ., 14, 291.
3Wagner, Ber., 27, 1636.

4Berkenheim, Ber., 25, 686.

5Masson and Reychler, Ber., 29, 1843.

6Konowaloff, Journ. Russ. Phys. Chem. Soc., 32 (1900), 76.
TTschugaeff, Ber., 32, 3332.

MENTHENE. 127

ing menthol, dissolved in dry toluene, successively with sodium,
carbon bisulphide, and methyl iodide. Menthyldixanthogenate
also yields menthene on distillation ; the specific rotatory power
of the menthene derived from these two compounds is [a],)=
111.56° to 116.06°.

Andres and Andreef* state that the fraction boiling between
. 160° and 170° of peppermint oil consists of a mixture of a
terpene, C,,H,,, with a hydrocarbon, C,,H,,. The experiments
published by these chemists do not determine whether the latter
hydrocarbon is identical with menthene, as might be supposed
from the occurrence of menthol and menthone in peppermint
oil. According to Labbé,? menthene occurs in the oil of
thyme.

Menthene is an oil having a slight odor unlike that of men-
thol, and boils at 167° to 168°, considerably lower than carvo-
menthene ; according to Sicker and Kremers, its specific gravity
is 0.814 at 20°, while Brihl* gives the sp. gr. 0.8064 at 20°.
Brihl has also determined other physical constants of menthene.
It is optically dextrorotatory, [a], = + 32.77° (Urban & Krem-
ers‘). Masson and Reychler® appear to have prepared a levo-
rotatory menthene from menthyl chloride, and they give its spe-
cific rotatory power, [a], = — 48.5°. Of especial interest is
Berkenheim’s observation that dextrorotatory menthene and
levorotatory menthyl chloride are obtained by heating inac-
tive menthyl chloride with potassium acetate and glacial acetic
acid ; under the influence of potassium acetate the dextrorotatory
portion of inactive menthyl chloride is converted into menthene,
whilst the levorotatory portion remains unchanged. In this
connection, attention should be called to the fact that Berkenheim
found the boiling point of this menthene at 170° to 171° (mer-
cury of thermometer in vapor). In general, the results of differ-
_ ent investigators do not agree on all points concerning this hydro-
carbon.

According to Baeyer, menthene unites with hydrogen iodide,
forming tertiary menthyl iodide ; menthene may also be converted
into tertiary menthol® by heating the hydrocarbon with trichlor-
acetic acid for half an hour at 70° to 90°, and agitating the
product for several hours with potash (see tertiary menthol).

1Andres and Andreef, Ber., 25, 609.

2H. Labbé, Bull. Soc. Chim., 79 (1898, III.), 1009.

$Briihl, Ber., 25, 151.

4Urban and Kremers, Ammer. Chem. Journ., 16, 395; Proc. Ammer.
Pharm. Assoc., 1892, 273; 1893, 185.

5Masson and Reychler, Ber., 29, 1843.

128 THE TERPENES.

It combines with bromine producing an oil. Brihl' found
that cymene is quite readily obtained by heating menthene with
anhydrous copper sulphate at 250°.

The compounds resulting from the addition of hydrochloric and
hydrobromic acids to menthene appear to be identical with the
menthyl! chloride and bromide obtained from menthol.’

Menthene nitrosochloride, C,,H,, NOCI, has been investigated
by Kremers* and his students. It is prepared by slowly adding
a solution of eighteen cc. of concentrated hydrochloric acid in
eighteen cc. of glacial acetic acid to a well cooled mixture of
forty-five cc. of menthene, forty-five cc. of glacial acetic acid, and
thirty-three cc. of ethyl nitrite. The resulting nitrosochloride is
purified by dissolving in chloroform, and precipitating with
alcohol. The products thus obtained from various fractions of
dextro-menthene, boiling from 166.5° to 168.5°, have different
melting points, from 106° to 122°; the compound having the
highest melting point, 121° to 122°, is levorotatory, [e]p>=—
2.4508°, while the other nitrosochlorides are inactive or dextro-
rotatory, [4]p= + 1.015° to + 20.64°, and melt from 106° to
119°. No satisfactory method has yet been found by means of
which the different modifications of the nitrosochloride can be
separated from the mixture.

It should further be noted that Urban and Kremers* obtained
an inactive nitrosochloride, melting at 128°, and that Baeyer® has
mentioned a menthene nitrosochloride, melting at 146°. Tschu-
gaeff® has also prepared a nitrosochloride, melting at 127° and
having [a], = 242.5°.

Menthene nitrosate, C,,H,,°N,O,, melts at 98°, and is optically
inactive (Urban and Kremers).

Menthene nitrolbenzylamine,

NO

Cy Hyg
NH - CH, - C,H,

is prepared in the usual manner from the nitrosochloride or nitro-
sate. It is optically inactive, and melts at 105.5° to 107°. Ac-

1Briihl, Ber., 25, 151.

2Wagner, Ber., 27, 1636; Kondakoff, Ber., 28, 1618; Journ. pr. Chem., 60
[II.], 257.

*Sicker and Kremers, Amer. Chem. Journ., 14, 292; Urban and Kremers,
Amer. Chem. Journ., 16, 395; Richtmamn. and Kremers, Amer. Chem.
Journ., 18, 762.

4Urban and Kremers, Amer. Chem. Journ., /6, 395.

5Baeyer, Ber., 26, 2561.

6Tschugaeff, Ber., 32, 3332.

~ = Pee vtec ent ch

oA —. rete. *

NITROSOMENTHENE. . 129

cording to Richtmann and Kremers, the nitrosochlorides having
specific rotatory powers differing by 30° all yield optically in-
active benzylamine bases, melting at 105.5° to 106.5°.

Nitrosomenthene,' C,,H,,NOH, is obtained by boiling menthene
nitrosochloride with alcoholic potash. It also results when the
nitrosochloride is heated in a tube at about 115°; in this case
hydrochloric acid is given off, and the resultant nitrosomenthene
sublimes slowly, and condenses in the cooler parts of the tube. It
is purified by distilling in a current of steam, and melts at 65° to
67°. Nitrosomenthene prepared from dextrorotatory menthene
nitrosochloride is levorotatory, and the inactive modification is
formed from the inactive nitrosochloride.

By reduction of nitrosomenthene with zinc dust and acetic acid,
Urban and Kremers obtained inactive menthone and a menthyl-
amine; this base forms a crystalline nitrate, which, on treating
with nitrous acid, yields an alcohol, C,,H,,OH, boiling at 210°
to 215°.

Nitrosomenthene is fairly stable towards sulphuric and acetic
acids. When it is warmed with hydrochloric acid, a ketone,
menthenone, C,,H,,O, is formed ; it boils at 206° to 208°, and is
reconverted into nitrosomenthene by heating with hydroxylamine.

The oxidation of menthene with potassium permanganate has
been studied by Wagner? and Tolloczko.* According to Wagner,
the following products are obtained by oxidizing menthene at
about 0° with a one per cent. solution of permanganate.

1. Menthene glycol, C,,H,,(OH),.—This glycol is an oily, viscid
liquid, boiling at 129.5° to 131.5° under 13 mm. pressure ; it
partially solidifies after a time and crystallizes from ether, melt-
ing at 76.5° to 77°; the permanent liquid portions yield a diac-
etate, a monoacetate, and a terpene, C,,H,,, when treated with
acetic anhydride.

2. Ketone alcohol, C,,H,,O(OH).—This compound is a liquid,
having the specific gravity 0.9881 at 0°, and boils at 104.5° to
105.5° at 13.5 mm. pressure. It yields a phenylurethane,
C,,H,,O,N, melting at 157°, and an oaime, C,,H,,O,N, which
crystallizes from ether in microscopic tablets, melting at 132° to
133°.

3. Acetic acid, methyl adipic acid, and y-isobutyryl--methyl
valeric acid (oxymenthylic acid).—These acids are also formed
in the oxidation of menthone with potassium permanganate.

1Urban and Kremers, and Richtmann and Kremers.
2Wagner, Ber., 27, 1636.
3Tolloezko, Ber., 28, 926, Ref.

9

130 THE TERPENES.

Meta-menthene (1: 3-methyl-isopropyl-cyclohexene), CiHig is
a hydrocarbon, which has been prepared by Knoevenagel’ by
heating cis-symmetrical menthol with phosphoric anhydride at
110° to 130°. It isa liquid, having an odor resembling that of
turpentine, and is an unsaturated compound ; it boils at 169°
to 170° under a pressure of 746 mm., has a specific gravity
0.8197 at 16°/4°, the index of refraction, np = 1.45609, and the
molecular refraction, R = 45.67. .

According to Kondakoff,? a hydrocarbon, C,,H,,, is obtained
from the oil of buchu leaves; it boils at 174° to 176° at 762
mm. pressure, at 65° to 67° under 14 mm., has a specific gravity
0.8648 at 18.5°, and a specific rotatory power, x» = + 60.20°.
Its odor resembles that of peppermint.

Cyclo-linalolene, C,,H,,, will be described under linalolene.

19?

HYDROCARBONS, C,,H,,.

Many members of the terpene series are converted into hydro-
carbons, C,,H,,, by heating with hydriodic acid and red phos-
phorus at about 200°. A sharp characterization and identification
of these compounds have been impossible, since they are chemic-
ally very indifferent substances, and their transformations into
crystalline derivatives have not yet succeeded. It is probable,
therefore, that some of the following hydrocarbons, which are
chiefly named after the products from which they are derived, are
identical. It is to be noted that, according to Baeyer’s nomencla-
ture, hexahydrocymene is called terpane, while Wagner suggests
.the name menthane.

Tetrahydropinene, C,,H.,, is described by Wallach and Berken-
heim* as a hydrocarbon produced by the hydration of pinene
hydrochloride ; it boils at 162°, has the specific gravity 0.795,
and the refractive index, n, = 1.43701°, at 20°. Bromine acts
on it, forming substitution products ; nitric acid and a mixture of
nitric and sulphuric acids do not attack this hydrocarbon in the
cold, but warm nitric acid dissolves and oxidizes it. A warm so-
lution of permanganate oxidizes it very slowly, forming valeric
acid. The hydrocarbon obtained by Orlow‘ by the direct hydra-
tion of oil of turpentine should in all probability be regarded as
tetrahydropinene.

1Knoevenagel and Wiedermann, Ann. Chem., 297, 169.
2Kondakoff, Journ. pr. Chem., 54, 433.

3Wallach and Berkenheim, Ann. Chem., 268, 225.
Orlow, Ber., 16, 799.

META-MENTHANE. i pee

Tetrahydrofenchene, C,,H,,, was obtained by Wallach’ in the
reduction of fenchyl alcohol, fenchone and fenchylamine with
hydriodic acid and phosphorus. It boils at 160° to 165°, and has
the specific gravity 0.7945 and index of refraction, n, = 1.4370,
at 22°. In its chemical behavior it resembles tetrahydropinene ;
bromine acts upon it forming a solid substitution-product, although
the yield is extremely small. This bromide crystallizes from
ethyl acetate in the form of needles, which melt above 200°, but
they have not been analyzed.

Starodubsky obtained a hydrocarbon, C,,H,,, in a similar manner .
from camphor ; it boils at 167° to 169°, and has the specific
gravity of 0.8114 at 15°.

A hydrocarbon, C,,H,5, is obtained by the reduction of terpine
hydrate ; it boils at ‘168° to 170°, and has the specific gravity
0.797 at 15° (Schtschukarew ’).

The hydrocarbon, C,,H,,, prepared by Wagner* by the action
of concentrated sulphuric acid on menthol, is to be regarded as
hexahydrocymene, and, according to Wagner, is called menthane.
The same compound is also formed by the reduction of menthol
with hydriodic acid and phosphorus, and is designated by Berken-
heim * as menthonaphthene. According to Wagner, it boils at 168°
to 169°, and has the sp. gr. 0.8066 at 0°; according to Berken-
heim, it boils at 169° to 170.5°, and has the specific gravity
0.8067 at 0° and 0.796 at 15°

Jiinger and Klages® state that this hexahydrocymene is best
prepared by reducing menthyl chloride with sodium and alcohol,
and shaking the reaction-product with concentrated sulphuric acid.

Meta-menthane® (1: 3-methyl-isopropylcyclohexane), C,,H,,, i
prepared by the reduction of symmetrical menthyl iodide. It
boils at 167° to 168° under a pressure of 756 mm., hasa specific
gravity 0.8033 at 14°/4°, refractive index, np = 1.44204, and
molecular refraction, R = 46.02. It is not acted upon by con-
centrated sulphuric and nitric acids, bromine, and solutions of
potassium permanganate.

A hexahydrocymene, ©,,H,,, isolated by Renard’ from the
essence of resin by means of sulphuric acid, boils at 171° to 178°,
and has the specific gravity 0.8116 at 17°.

1Wallach, Ann. Chem., 284, 326.

2Schtschukarew, Ber., 23, 433c.

sWagner, Ber., 27, 1638.

4Berkenheim, Ber., 25, 686.

5Jiinger and Klages, Ber., 29, 317.

Knoevenagel and Wiedermann, Ann. Chem., 297, 169.
Renard, Ann. Chim. Phys. [6], 1, 223.

132 THE TERPENES.

Berkenheim' has published the results of experiments on the
relations of the naphthenes, C,,H,,, occurring in Russian petroleum,
to the hydrocarbons under consideration, and to the terpenes.

Diethyl hexamethylene, C,,H,,, was synthetically prepared by
Zelinsky and Rudewitsch.? According to these chemists, diethyl-
keto-hexamethylene, C,,H,,0, is obtained by the distillation of
diethyl pimelic acid over calcium hydroxide; it boils at 205° to
207°. This ketone is converted by reduction into the alcohol,
C,,H,,OH, which boils at 209° to 211°, and partially solidifies,
the crystalline portion melting at 77° to 78°. This alcohol is
converted into the iodide, C,,H,,I, by treatment with hydriodic
‘acid, and when the iodide is reduced with zine and hydrochloric
acid in alcoholic solution it yields diethyl hexamethylene. The
following formulas express these reactions :

ss RG as

HC; 2H,
H. H
2 2
H,
Diethyl-keto-hexamethy-
lene. ‘
zs H,

2
Alcohol, C,)H,,OH.

2 H
=> ney Com
H, H,
Na

C
Diethyl hexamethylene.

Iodide, C,,H,,I.

Diethyl hexamethylene is a colorless liquid with a petroleum-
like odor. It bvils at 169° to 171°, has the specific gravity,
d 22°/4° = 0.7957, and the refractive index, n, = 1.4388, at 20°.
It is a saturated hydrocarbon, and is immediately colored by bro-
mine vapor.

1Berkenheim, Ber., 25, 686.
*Zelinsky and Rudewitsch, Ber., 28, 1341.

OXIDIZED COMPOUNDS RELATED TO THE TERPENES,
C,H

10-16"

1. SUBSTANCES WHICH CAN NOT BE REGARDED AS
DERIVATIVES OF THE HYDROCYMENES.

i

(ANALOGUES OF PINENE, CAMPHENE AND
FENCHENE.)

1. CAMPHOR, C,,H,,0.

Dextrorotatory camphor (Japan camphor) is found in the
camphor tree (Laurus camphora), while levorotatory camphor
occurs in the oil of Matricaria parthenium, and has, therefore,
been designated as Matricaria camphor. Camphor may be pre-
pared artificially by oxidizing borneol and isoborneol with nitric
acid.

Of especial interest is a’partial synthesis of camphor which
Bredt and v. Rosenberg’ have accomplished. They obtained cam-
phor by the dry distillation of the calcium salt of homocamphoric
acid, prepared from camphonitrile ;* accepting Bredt’s formula of
camphor (see page 25), this reaction may be expressed by the
equation :

f CH CH,—COO. H, CH CH,
H,C—O—CH, Ca = CaCO, + ne-}-on, |
H, ooo CH, cO

H; H;

This synthesis of camphor * is quite analogous to the syntheses
of many keto-pentamethylenes, which have been prepared by J.
Wislicenus and his students.

1Bredt and v. Rosenberg, Ann. Chem., 289, 1.

2Haller, Théses présentées a la faculté des sciences de Paris; compare
Claisen, Ann. Chem., 281, 349.

3A. Haller, Bull. Soc. Chim., 15, 1896 (III.), 324.

133

134 THE TERPENES.

Camphor forms a colorless, transparent, tough mass, which
crystallizes from alcohol; it is very volatile, sublimes easily,
melts at 175° and boils at 204°. Its specific rotatory power is
[a] p= + 44.22°.

Optically inactive camphor is obtained by mixing together the
solutions of equal weights of the active modifications, or by oxi-
dizing inactive borneol ; it melts at 178.6°.

Camphor is resolved into para-cymene and water when it
is treated with phosphorus pentoxide; it is converted into car-
vacrol by heating with iodine. According to Bredt,’ both
of these changes involve the formation of carvenone, C,,H,,O,
as an intermediate product. The transformation of camphor
into carvenone also takes place under the influence of con-
centrated sulphuric acid at 105° to 110°; the carvenone is
either the direct product, or, more probably, results from dihy-
drocarvone, which is readily converted into carvenone by the in-
fluence of acids.

« Gamphren ”? is formed by heating 200 grams of camphor with
800 grams of concentrated sulphuric acid at 105° to 110°.

A mixture of borneol with about twenty per cent. of isoborneol
is formed by reducing camphor in an alcoholic solution with
sodium. Nitric acid oxidizes camphor into a product which con-
sists chiefly of camphoric acid (m. p. 187°) and camphoronic acid
(m. p. 139°); Bredt formulates this reaction as follows :

a o—— CH OH, H, OH: COOH H OH
a ee = 1 HOY = noon,
H, ‘ CO CH, y COOH éH,—c——-cooH
H, GH, © be,
Camphor. Camphoric acid. Camphoronic acid.

The discussion of camphor and its derivatives must necessarily be
limited owing to the reasons mentioned in the introduction. Only
those compounds will be briefly considered which are very nearly
related to other members of the terpene group, and which are to
be regarded as the parent-substances of certain terpene amido-
compounds derived from camphor, or which may be converted by
simple reactions into camphene, a terpene closely allied to cam-

1Bredt, Rochussen, and Monheim, Ann. Chem., 314, 369.

2 Armstrong and Kipping, Journ. Chem. Soc., 63, 77; compare Bredt, Ann.
Chem., 314, 369.

CAMPHOROXIME ANHYDRIDE. 135

phor. The most important of these derivatives are camphoroxime,
borneol, isoborneol, and substances obtained from them.

Camphoroxime,’ C,,H,,. NOH, was discovered by Nigeli.2 In
order to prepare it, dissolve twenty parts of camphor in two
and one-half times its quantity of ninety per cent. alcohol, add
twelve parts of hydroxylamine hydrochloride and a little more
than the calculated amount of sodium bicarbonate, and warm
the mixture for some time. The reaction is complete when the
product wholly dissolves in dilute sulphuric acid. It crystal-
lizes from petroleum ether in brilliant, hard, monoclinic’ prisms,
which, like those of the active tartaric acids, are hemimorphic
(Beckmann‘).

Camphoroxime melts at 118° to 119°, boils with slight decom-
position at 249° to 250°, and smells like camphor. The presence
of an oximid group is proved by the formation of a sodium salt,
an ethyl ester, and a compound with phenyleyanate,’ which melts
at 94°.

Leuckart and Bach® obtained bornylamine, C,,H,,NH,, by re-
duction of camphoroxime with sodium and alcohol; they also
prepared the same base by the action of ammonium formate on
camphor.

The action of nitrous acid on camphoroxime has been investi-
gated by Angeli and Tiemann.’

Camphordioxime, see Angelico, Atti. Real. Accad. Lincei, 1900
(V.), 9 (IL.), 47.

Camphoroxime anhydride (a-campholenonitrile), C,,H,,N, was
first prepared by Niigeli® by the action of acetyl chloride on cam-
phoroxime; it may also be obtained by the action of other dehy-
drating agents? on camphoroxime, most readily by boiling with
dilute sulphuric acid.

1Forster, Journ. Chem. Soc., 71, 191 and 1030; 75, 1141; 77, 251.

*Nigeli, Ber., 16, 497; see Konowaloff, Journ. Russ. Phys. Chem. Soc., 33
(1901), 45; Auwers, Ber., 22, 605.

3Muthmann, Ann. Chem., 250, 354.

*Beckmann, Ann. Chem., 250, 354.

5Goldschmidt, Ber., 22, 3104.

SLeuckart and Bach, Ber., 20, 104; see Konowaloff, Journ. Russ. Phys.
Chem. Soc., 33, 45; Forster, Journ. Chem. Soc., 73, 386.

TAngeli and Rimini, Ber., 28, 1077; Angeli, Ber., 28, 1127; Tiemann, Ber.,
28, 1079; Angeli and Rimini, Gazz. Chim., 25 [1], 406; Ber., 28, 618, Ref.

Tiemann, Ber., 29, 2807; Angeli, Gazz. Chim., 26 (II.), 29, 34, 45, 228,
502 and 517; 28 (I.), 11; Mahla and Tiemann, Ber., 33, 1929.

8Nigeli, Ber., 16, 497.

9Goldschmidt and Ziirrer, Ber., 17, 2069 and 2717; Goldschmidt and
Koreff, Ber., 18, 1632; Leuckart, Ber., 20, 104; Goldschmidt, Ber., 20, 483.

136 THE TERPENES.

It boils at 226° to 227°, and at 20° has the specific gravity
0.910 and the coefficient of refraction 1.46648, corresponding to
the molecular refraction 45.39 (Wallach’). Its specific rotatory
power in a one decimeter tube is [a], = + 7.5 (Tiemann ’).

It is an unsaturated compound and combines directly with
halogen acids, forming oily addition-products (Wallach ').

By reduction with zinc and sulphuric acid,’ or better with
sodium and alcohol,’ a-campholenonitrile yields a-camphylamine,
C,,H,,NH,. When hydrogen chloride is passed into an alcoholic
solution of the nitrile,° a-campholenic acid is produced, together
with some isoamidocamphor, C,,H,,O. NH,,.

a-Campholenamidoxime, C,,H,,(NOH). NH,,is produced by heat-
ing a-campholenonitrile with aqueous hydroxylamine under pres-
sure ; it crystallizes in white needles, and melts at 102°.

Isocamphoroxime (a-campholenamide), C,H,,CONH,, is formed,
together with a-campholenic acid, by heating camphoroxime anhy-
dride with alcoholic potash ; it crystallizes in leaflets, melting at
125° (Nageli®). It has the specific rotatory power, [a])=
— 4.06°. Warm, dilute sulphuric acid converts it into the sul-
phate of isoamidocamphor, and, under certain conditions, into
dihydrocampholenolactone, C,,H,,O,. It is quite readily changed
into a-campholenic acid by boiling with alcoholic potash.

a-Campholenic acid, C,H,,. COOH (Goldschmidt and Ziirrer,’
and Tiemann). This acid is identical with the “ oxycamphor”
obtained by Kachler and Spitzer ;* it boils at 256°, has the
specific gravity 0.992 at 19°, and the refractive index, np =
1.47125, from which the molecular refraction equals 47.36.
Its specific rotatory power in a one decimeter tube is [a], = +
9° 37’.

a-Dioxydihydrocampholenic acid,’ C,H,,O,. COOH, was first pre-
pared by Wallach. It is formed by the oxidation of an ice-cold
solution of sodium a-campholenate with a two per cent. solution
of potassium permanganate." It melts at 144°, and has [a],
= + 58.08°.

Wallach, Ann. Chem., 269, 330.

2Tiemann, Ber., 29, 3006.

8Goldschmidt and Koreff, Ber., 18, 1632.

‘Goldschmidt, Ber., 18, 3297; Goldschmidt and Schulhoff, Ber., 19, 708.
5F, Tiemann, Ber., 29, 3006; 30, 242, 321 and 404,

®Nigeli, Ber., 17, 805; Tiemann, Ber., 29, 3006.

7Goldschmidt and Ziirrer, Ber., 17, 2069 and 2717.

8Kachler and Spitzer, Ber., 17, 2400; Monatsch. fiir Chem., 3, 216; 4, 643.
*Tiemann, Ber., 29, 3006; Wallach, Ann. Chem., 269, 327 and 343.
Compare with Bouveault, Bull. Soc. Chim., 19, 1898 (III.), 565.

CAMPHOR. 137

In the following is presented a very brief outline of a discussion
which was carried on between Leuckart and Goldschmidt regard-
ing the structure of the compounds described above (these com-
pounds were not at that time designated as alpha-derivatives).

‘The formulas of these substances are :

According to Leuckart, According to Goldschmidt,
Ber., 20, 104. Ber., 20, 483.
/CH CH,
Cot | syaseuasver Camphor..........+. GHC
CH, : /os
3 Kno siyawans Camphoroxime......... Cy he canis
CH, B CH,
vieserioass ornylamine.......... Ke
OA be NH, Te NH,
y CH
Pal Cen pened Camphoroxime......... oln,Z :
CHK | : ine
abs ol. Sl Wa anhydride. CN
CH.NH, JOE
eg aks Camphylamine....... C,
be, * "*\ cH,.NH,
CH.NH, : JOH:
C,H, d Isocamphoroxime. (CO, #\ CON,
CHOH JOH,
Rosie Campholenic acid.......C
8 KI ip 8 *\ COOH
fee ere Campholene...............CgH,,—CH,

The most important fact which Goldschmidt and Ziirrer ad-
duce to support their view that camphoroxime anhydride is to be
regarded as a nitrile of a monobasic acid, is their observation that
a hydrocarbon, C,H,,, campholene (b. p. 130° to 140°), is ob-
tained by the dry distillation of the calcium salt of campholenic
acid ; further, an amidine’ (m. p. 114° to 115°), is formed by

1Goldschmidt and Koreff, Ber., 18, 1633.

138 THE TERPENES.

heating the anhydride with toluidine hydrochloride according to
Bernthsen’s method.

It should also be mentioned that Bamberger’ has accepted
Goldschmidt’s views, but has advanced the opinion that campho-
lenonitrile is a cyanide having an open chain of carbon atoms,
and has the formula :

H C,H, gH,
H, ii H,¢ CH,
H N
H NOH
y ¥
CH; H;
Camphoroxime. Campholenonitrile.

Wallach’s experiments, however, have proved that Bamberger’s
assumption is not well founded, hence a brief consideration of these
experiments is given in the following.

According to Wallach, ? campholenic acid is unsaturated ; when
bromine is added to its alcoholic or acetic acid solution, it forms
a product which eventually becomes crystalline, and is insoluble
in alkalis. Potassium permanganate, which is decolorized by
sodium campholenate even in the cold, converts campholenic
acid into a-dioxydihydrocampholenic acid, C,,H,,O,; it separates
from hot water in splendid crystals, melts at 144° to 145°, and
yields a silver salt, C,,H,,O,Ag, and is, therefore, a monobasic
acid.

A saturated hydrocarbon is produced when campholenic acid
is heated with concentrated hydriodic acid and red phosphorus ;
it boils at 135° to 145°, and probably contains as chief con-
stituent, dihydrocampholene, C,H...

These experiments show that campholenic acid, and likewise
campholenonitrile, contain a cyclic structure of the carbon atoms,
and one double linkage.

That campholenic acid is unsaturated and has a cyclic arrange-
ment of its carbon atoms, has also been proved by W. Thiel.* In
consideration of these facts, and by employing the formula of
camphor proposed by himself, Bredt* explains the constitution of

'1Bamberger, Ber., 21, 1125.

2Wallach, Ann. Chem., 269, 327 and 343.

sThiel, Ber., 26, 922; compare also under pinene.
4Bredt, Ber., 26, 3054.

DIHYDROCAMPHOLENIMIDE. 139

campholenonitrile and of campholenic acid by the following for-
mulas, which he regards as the most probable :

1H, CH CH,
“na if = HyC—/—CH, |
CNOH ,

iS Pa 2, O
eos
CH, NH
pecans zt Intermediary product.
CH, CH. CH,
H, CH, COOH
H,C—C—CH;
HC Hy;
i CH oe
CH; Campholenic acid.
Campholenonitrile.

According to researches of Béhal,' and of Tiemann,’ a second
group of isomeric compounds is derived from camphoroxime ;
Tiemann designates these as beta-compounds.

#-Campholenonitrile,’ C,H,,.CN, is obtained when camphoroxime
is boiled for some time with dilute hydriodic acid. It boils at
225° and is optically inactive ; when reduced in alcoholic solution
with sodium, it gives rise to S-camphylamine, C,,H,,NH,,.

$-Campholenamide,’ C,H,,CONH,, is prepared by the saponifi-
cation of the f-nitrile. It melts at 86°, and is optically inactive.

f-Campholenic acid,” C,H,,COOH, is formed by the hydrolysis
of §-campholenamide. It melts at 52°, and boils at 245°.

§-Dioxydihydrocampholenic acid,’ C,H,,O,- COOH, is formed by
the oxidation of f-campholenic acid with potassium permanganate.
It crystallizes from chloroform or water in needles, and melts at
146°.

Isocamphorone,* C,H,,O, boiling at 217° > and campholonie
acid,’ C,,H,,O,, a liquid ketonic acid, isomeric with the pinonic
acids, are also products of the oxidation of f-campholenic acid.

Isoamidocamphor,* C,,H,.O-NH.,, is prepared by treating cam-
phoroxime with twice ‘its “weight of hydriodic acid, sp. gr. 1.96.
It crystallizes in prisms, melts at 39°, and boils at 254°.

Dihydrocampholenimide,* C,,H,,O- NH, is obtained by distill-
ing isoamidocamphor under atmospheric pressure in such a

1Béhal, Compt. rend., 119, 799; 120, 858 and 1167; 121, 213.

2Tiemann, Ber., 28, 1082; 30, 242; see Blaise and Blanc, Compt. rend.,
129 (1899), 106; 1317 (1900), 803.

3Tiemann, Ber., 30, 242.

4Tiemann, Ber., 30, 321 and 404; see Mahla and Tiemann, Ber., 33, 1929;
Tiemann, Ber., 33, 2953 and 2960.

140 THE TERPENES.

manner that the substance becomes slightly superheated. It
crystallizes in white needles, melts at 108°, and boils at 266°.

Dihydrocampholenolactone,' C,,H,,O,, is produced when cam-
phoroxime is decomposed with moderately concentrated sulphuric
acid, the liquid diluted with water, and then boiled for some time.
Tiemann explains this change by assuming that a-campholenoni-
trile is the first product, and that this compound passes at once
into the 8-modification, which, in turn,is hydrolyzed to f-campho-
lenamide ; this is changed into isoamidocamphor, which loses am-
monia forming dihydrocampholenolactone. It melts at 30°, boils
at 256°, has the specific gravity 1.0303, the refractive index,
ny = 1.46801, and the molecular refraction, M = 45.79. It is
optically inactive.

Campholene,’ C,H,,, is formed by boiling a- and f-campholenic
acids so that the material becomes slightly superheated. It boils
at 133° to 135°, has a specific gravity 0.8034 at 20°, refractive
index, np = 1.44406, at 20°, and molecular refraction, M = 41.00.

As a result of his investigations * on camphor and the campho- °
lene group, as well as from the researches of Tiemann and Mahla*
on the oxidation products of camphoric acid, Tiemann concludes
that the formula of camphor, which he has proposed and made to
conform with Bredt’s acceptance of a hexamethylene ring formed
by the combination of two pentamethylene rings, is proved.
Whether this opinion is correct, the future investigations must
determine. At the present time, the question regarding the con-
stitution of camphor seems to be an open one, notwithstanding
the great amount of work which has been carried on regarding it.

Camphor semicarbazone, C,,H,, = N-NH-CO-NH,, melts at
236° to 238° (Tiemann’).

Oxymethylene camphor,

is obtained by the action of sodium and amyl formate on a solu-
tion of camphor in ether (Claisen). It is a white, crystalline sub-
stance, melts at 80° to 81°, and when dissolved in water or

(He) 68. Ber., 30, 321 and 404; Bouveault, Bull. Soc. Chim., 19, 1898

2Tiemann, Ber., 30, 594.

STiemann, Ber., 28, 1079, 2166; 29, 119, 3006; 30, 242, 321, 404, 594; 33, -
2935; compare Bredt, Ann. Chem., 289, 15; Forster, Journ. Chem. Soc., 75,
1141; 79, 108; Walker, Journ. Chem. Soc., 63, 495; 67,347; 77, 394; Blane,
Bull. Soe. Chim., 1900 [III.], 23, 695.

_‘Mahla and Tiemann, Ber., 28, 2151; 29, 2807; 33, 1929; compare Bal-
biano, Ber., 30, 289, 1901; Real. Accad. dei Lincei, 8 (1899), 422; Gazz.
Chim., 29 (II.), 490.

5Tiemann, Ber:, 28, 2191; see also Rimini, Gazz. Chim., 30 (I.), 600.

fag et

BORNEOL. 141

aqueous alcohol, it turns blue litmus paper red. Its alcoholic
solution is colored reddish-violet by the addition of ferric chloride ;
a further addition of this reagent produces a blue, and finally a
dark green color. It has been carefully investigated by Bishop,
Claisen, and Sinclair."

Campholic acid, C,H,,COOH, is the parent-substance of cam-
pholamine and camphol alcohol; it is prepared by the method
given by Errera.?_ To a boiling solution of 500 grams of cam-

phor in 250 grams of benzene, thirty-eight grams of sodium

are gradually added; the benzene is then distilled off, and the
residual mass is heated at 280° for twenty-four hours. The
reaction-product is treated with water, shaken with ether, and the
aqueous solution acidified with hydrochloric acid; the resultant
campholic acid is distilled with steam. A yield of twenty per
cent. may be obtained by careful treatment of the mother-liquor.

Campholamide, C,H,,CONH,, is produced by heating ammonium
campholate at 230°, or by treating the acid chloride with am-
monia. It crystallizes from water or petroleum ether in needles,
and melts at 79° to 80°.

Campholonitrile, C,H,,CN, is formed in large quantities as a by-
product in the preparation of campholamide, and is separated
from the latter by distillation with steam. It melts at 72° to
73°, boils at 217° to 219°, and resembles camphor in odor and
appearance. It yields campholamine on reduction with sodium
and alcohol (Errera’*).

For condensation-products of camphor with aldehydes, see in-
vestigations of Haller.*

Camphor pinacone, C,,H,,.O,, is formed, together with borneol,
by the reduction of camphor in indifferent solvents ; it is odor-
less, tasteless, very slightly volatile with steam, crystallizes in
rhombic pyramids, and melts at 157° to 158°. Dextro-camphor
yields a levorotatory pinacone, while levo-camphor gives rise to a
dextrorotatory derivative. Various derivatives of this pinacone
have been prepared (Beckmann’).

2. BORNEOL, C,,H,,OH.

Borneol occurs in nature in an optically dextrorotatory and
levorotatory, as well as in an inactive, modification ; it is found

1Bishop, Claisen and Sinclair, Ann. Chem., 281, 314.

2Hrrera, Gazz. Chim., 22 [1], 205; Ber., 25, 466, Ref.

8Errera, Gazz. Chim., 22 [2], 109; Ber., 26, 21, Ref.

4A. Haller, Compt. rend., 128, 1270; 130, 688; 133, 79; see also Hel-
bronner, Compt. rend., 133, 43.

5E. Beckmann, Ber., 22, 92; 27, 2348; Ann. Chem., 292, 1; Journ. pr.
Chein. [II.], 55, 31.

142 THE TERPENES.

free, and also in the form of esters. The most important occur-
rence of dextro-borneol is in the pith cavities of Dryobalanops
camphora (“ Borneo-camphor’’); it is also found in oil of rose-
mary and oil of spike. The so-called ‘ Ngai-camphor” from
Blumea balsamifera consists of levorotatory borneol. Valerian
oil contains levo-borneol (“ Valerian-camphor”), and some in-
active borneol ; the latter modification has also been found in oil
of sage. In the form of esters of the lower fatty acids, especially
acetic acid, levo-borneol is a constituent of many fir and pine
oils; thus, Bertram and Walbaum’ have detected it in pine needle
oil from Abies alba, Canadian pine oil, hemlock oil, pine needle
oils from Picea excelsa and Pinus montana, while Hirschsohn* has
found it in the oil of Abies siberica L. In the same manner bor-
neol occurs in oil from Satureja thymbra L., oil of golden rod,
sage oil, and oil of thyme. According to Kremers,* the oil of
Picea nigra is especially rich in levo-borny] acetate.

Borneol (“levo-camphenol” *) is produced by heating French
oil of turpentine with benzoic acid at 150° for fifty hours.

For the preparation of borneol from camphor the following
method is employed; it is Wallach’s® modification of the old
method proposed by Jackson and Menke,® and Immendorf.’

Fifty grams of camphor are dissolved in 500 ce. of ninety-
six per cent. alcohol in a spacious flask connected with a wide
reflux condenser, through which sixty grams of sodium are
gradually added. The operation should require about one hour
for its completion, and the spontaneous rise of temperature must
not be prevented by cooling; it is in fact advisable when the
reaction eventually becomes moderate, to accelerate the solution
of the last portions of sodium by the careful addition of about fifty
ec. of water. When the sodium is dissolved the product is
poured into three or four liters of water, the separated borneol is
filtered, pressed on a porous plate and crystallized from petroleum
ether.

According to Bertram and Walbaum,' the borneol so prepared
is not pure, but contains about twenty per cent. of isoborneol.

1Bertram and Walbaum, Arch. Pharm., 231, 290.

*Hirschsohn, Pharm. Zeitsch. f. Russland, 1892, No. 38.

8Kremers, Pharm. Rundschau, 13, 135.

*Bouchardat and Lafont, Compt. rend., 113, 551; 125, 111.

5Wallach, Ann. Chem., 230, 225.

6Jackson and Menke, Ber., 15, 16 and 2730.

tImmendorf, Ber., 17, 1036.

’Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 12; see Beckmann,
Journ. pr. Chem., 55, 1897 (II.), 31.

METHYL BORNYL ETHER. 143
These chemists obtained chemically pure borneol by saponification
of crystalline borny] acetate.

Beckmann’ effected the reduction of camphor into borneol by
repeated, alternate treatment of a solution of camphor in ether
with sodium and water.

PROPERTIES.—Borneol, prepared by Wallach’s method, melts at
_ 206° to 207°; pure borneol derived from its acetate, or from
“borneo-camphor,” or from oil of valerian, melts at 203° to
204°. It boils at 212°, and crystallizes in hexagonal plates
(Traube’).

Its solution in petroleum ether unites with bromine, forming a
yellowish-red, unstable additive compound, which soon decom-
poses on standing in the air (Wallach *).

Two molecules of borneol combine with one molecule of hydro-
bromic or hydriodic acid, yielding compounds which are easily
decomposed.

If borneol be oxidized with nitric acid (sp. gr. 1.4), camphor
results. Camphene is formed when borneol is heated with acid
potassium sulphate.

Several esters of borneol have been synthetically prepared by
Bertram and Walbaum ;‘ the properties of these compounds are
given in the following table :

Boiling Point, | po, 0ptical | Sp-Gr. at | Refraction np ror Eetee
Goan) "| Beaton 200) SP ps S| Uae,” [Defermined by
Formate. 90° +31° 1.013 1.47078 97.89
Acetate. Bue. F4, —88° 20/ 0.991 1.46635 100.60
Propionate. | 109° to110°| -+24° 0.979 1.46435 97.07
Butyrate. 120° to 121°}; +22° 0.966 1.46380 99.20
Valerate. 128° to 180° + 20° 0.956 1.46280 98.56

Bornyl acetate, C,,H,,O-COCH,, is of especial importance, since
it is a constituent of the oil of pine needles, and because it is a solid
Tt melts at 29° and
forms orthorhombic, hemihedral crystals (Traube).

Methyl bornyl ether, C,,H,.OCH,, was prepared by Baubigny’

and possesses great power of crystallization.

and by Briihl.®

It is a liquid, boiling at 194° to 195°.

1Beckmann, German patent, No. 42458; Ber., 21, 321, Ref.; 22, 912.
*Traube, Journ. pr. Chem., N. F., 49, 3.
sWallach, Ann. Chem., 230, 226.
‘Bertram and Walbaum, Arch. Pharm., 231, 303; see also Minguin,
Compt. rend., 123, 1296.
5Baubigny, Ann. Chim. Phys. [4], 19 (1870), 221.
SBriihl, Ber., 24, 3377 and 3713.

144 THE TERPENES.

Ethyl bornyl ether, C,,H,,OC,H,, is obtained by repeated treat-
ment of a solution of borneol in xylene with sodium and ethyl
iodide. It is a thick liquid having an unpleasant odor, and boils
at 97° at 20 mm. and at 204° to 204.5° under 750 mm. pres-
sure; its specific gravity is 0.9008 at 20°.

A compound ' called ethyl bornyl ether (?) is formed, together
with camphene, by the action of alcoholic potash on pinene hydro-
chloride; it has a sp. gr. 0.9495 at 0° and a rotatory power,
[a] >= + 26.3°.

Methylene bornyl ether, (C,,H,,O),CH,, is formed in a similar
manner to the ethyl ether. It separates from ligroine in well
formed, orthorhombic crystals, and melts at 167° to 168°
(Brihl?). Brihl has also examined the physical properties of
this compound.

Borneol, like other alcohols, combines with chloral and bromal
to form compounds, which are analogous to the chloral-alcohol-
ates. The borneol-chloral compound melts at 55° to 56°, and
the bromal derivative melts at 98° to 99° (Haller* and Min-

uin *),
R sa phenylurethane, C.LH,NH-CO.OC,,H,,, was first pre-
pared by Leuckart® by the action of phenyl isocyanate on borneol.
It melts at 138° to 139° (Bertram and Walbaum °).

The urethane and the above-mentioned compounds of borneol
with chloral and bromal yield borneol on treatment with alco-
holic potash.

Bornyl xanthic acid, C,,H,,O-CS -SH, was obtained by Bam-
berger and Lodter’ by the action of carbon bisulphide on sodium
bornylate, and analyzed in the form of its cuprous salt.

Bornyl chloride, C,,H,,Cl, was described by Kachler * as borneol
chloride. It is most conveniently prepared by the following
method.®

Sixty grams (one molecule) of phosphorus pentachloride are
placed in a flask fitted with a tube containing sulphuric acid to
prevent access of moisture, and are covered with eighty cc. of very
low boiling petroleum ether; forty-five grams (one molecule) of
borneol are added in small portions (about five to eight grams)

‘Bouchardat and Lafont, Compt. rend., 104, 639.
2Briihl, Ber., 24, 3377 and 3713.

sHaller, Compt. rend., 112, 143.

4Minguin, Compt. rend., 116, 889.

5Leuckart, Ber., 20, 115.

SBertram and Walbaum, Arch. Pharm., 231, 303.
™Bamberger and Lodter, Ber., 23, 214.

8Kachler, Ann. Chem., 197, 93.

*Wallach, Ann. Chem., 239, 231.

BORNYL IODIDE. 145

at atime. After every addition of borneol a vigorous evolution
of hydrochloric acid takes place, due to the action of the penta-
chloride on the borneol, and a new portion of borneol is not added
until this evolution of gas is finished. The operation is complete
in about half an hour. The clear liquid is now poured off from
any excess of phosphoric chloride into a thick-walled separating
_ funnel of about one liter capacity, and the phosphorus com-
pounds are removed by careful and frequent agitation with a large
quantity of water. In case there is some doubt whether all of the
phosphorus oxychloride is decomposed, the petroleum ether solu-
tion of the bornyl chloride is eventually treated with alcohol,
which is removed by shaking with water. The solution is poured
into a shallow dish, and care is taken that the petroleum ether
evaporates as quickly as possible in a cold place. Pure bornyl
chloride is so obtained in a yield of about forty-five grams.

It appears and smells like camphor, melts at 157°, and dis-
solves readily in petroleum ether, less readily in alcohol, from
which it may be obtained in thread-like crystals. It yields cam-
phene when heated with aniline.

According to Reychler," and Jiinger and Klages,? bornyl
chloride is stereoisomeric with isobornyl chloride and camphene
hydrochloride, the two latter being identical.

According to Wagner,’ most of the borny] chloride, prepared as
above described, is readily converted into camphene by boiling
with alcoholic potash, and therefore consists chiefly of isoborny]
chloride (camphene hydrochloride), the borneol being at first
changed into camphene which then unites with one molecule of
hydrogen chloride ; a small proportion of the borny! chloride, how-
ever, is not as easily acted upon by the alcoholic potash, and
Wagner regards this as the true bornyl chloride, and that it is
identical with pinene hydrochloride.

Recent investigations by Semmler* also seem to indicate that
pinene hydrochloride is the true chloride corresponding with
borneol. |

Bornyl Iodide, C,,H,,I.—According to Wagner,’ a mixture of
borny!] iodide and another substance is formed when borneol is
moistened with a little water and saturated with hydrogen iodide at
the temperature of the water-bath ; the two compounds are sepa-
rated by boiling with alcoholic potash for thirty hours, the bornyl

1A, Reychler, Ber., 29, 697; Bull. Soc. Chim., 15, 1896 (III.), 366.
2Jiinger and Klages, Ber., 29, 544.

3G. Wagner and Brickner, Ber., 32, 2302.

4F. Semmler, Ber., 33, 774.

10

146 THE TERPENES.

‘iodide being only slowly attacked, yielding camphene, while the
other substance is readily acted upon by the potash, giving an oily
hydrocarbon.

Bornyl iodide boils at 118° to 119° at 16 mm. pressure, has
the specific gravity 1.4799 at 0° and 1.4617 at 20°, solidifies in
a freezing mixture, and melts at —13°; it is almost optically in-
active. Silver nitrate and acetic acid convert it into a mixture
of camphene, dipentene, and the acetates of borneol, isoborneol
and terpineol. Wagner regards it as identical with pinene hydrio-
dide in all respects except its optical rotation.

Methylenic acetal of borneol (diborneolic formal), CH,(O- C,,H,,),,
is a compound prepared by Brochet’ by the condensation of bor-
neol with formaldehyde in the presence of mineral acids. It melts
at 166°, and boils without decomposition at 344° to 345°.

According to a recent publication by Semmler,’ borneol is to be
regarded as a secondary alcohol, and is not stereoisomeric with
isoborneol.

3. ISOBORNEOL, C,,H,,OH.

It has been mentioned that camphene, C,,H,,, may be obtained
from borneol by a variety of methods based on the elimination of
water; on the other hand, methods are known by means of
which hydrocarbons of the terpene group may be converted into
alcohols. The most important of these methods is that proposed
by Bertram.’ While studying the effect of this method on cam-

phene, Bertram and Walbaum* made the interesting observation |

that borneol was not formed from camphene, but that the isomeric
alcohol isoborneol was obtained. Since the latter is also produced,
together with borneol, by the reduction of camphor with sodium
and alcohol, the isomerism of borneol and isoborneol cannot be
explained by a difference in position of the hydroxyl-group
(isomerism of position). ,

Montgolfier® had already shown that borneol (‘stable cam-
phol”) and a compound isomeric with borneol ( ‘instable cam-
phol”) are obtained by the action of alcoholic potash or of
sodium on camphor. Haller ® isolated the latter compound in a
pure condition, and called it “isocamphol.” This substance is
identical with Bertram and Walbaum’s isoborneol.

1A. Brochet, Compt. rend., 128, 612.

2¥. Semmler, Ber., 33, 774.

3Bertram, German patent, No. 67255.

‘Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 1.
5Montgolfier, Compt. rend., 83, 341.

SHaller, Compt. rend., 109, 187.

PREPARATION OF ISOBORNEOL. 147

Preparation of Isoborneol.!

One hundred grams of camphene are heated with a mixture of
250 grams of glacial acetic acid and ten grams of fifty per
cent. sulphuric acid at 50° to 60° for a few hours, the mixture
being frequently agitated. Since the acid mixture is not sufficient
for the perfect solution of the camphene, two layers are at first
- formed ; the volume of the upper one becomes gradually less, and
in a short time a perfectly clear, colorless or slightly reddish solution
results. The reaction is complete in two or three hours, and the
product is diluted with water, the resultant isoborny] acetate sepa-
rating as an oil. This is washed with water to remove the free
acid, and without further purification it is boiled for a short time
witha solution of fifty grams of potassium hydroxide in 250 grams
of ethyl alcohol in a flask, fitted with a reversed condenser. The
greater part of the alcohol is then distilled off,and the residue poured
into a large quantity of water ; isoborneol is precipitated as a solid
mass, which is filtered and recrystallized from petroleum ether.

It crystallizes in thin leaflets, and dissolves readily in alcohol,
ether, chloroform and benzene. It smells very like borneol, and
is so volatile and sublimes so easily that its melting point, 212°,
must be determined in sealed tubes, while its boiling point can-
not be determined. It is further distinguished from borneol by
its greater solubility in benzene and petroleum ether. According
to Traube’s measurements, published by Bertram and Walbaum,
isoborneol, like borneol, crystallizes in hexagonal plates, but dif-
fers from borneol in its positive character of double refraction.

Isoborneol is changed into ordinary camphor by oxidation”
with nitric acid or with a solution of chromic anhydride in glacial
acetic acid ; the identity of this product with Japan camphor is
especially established by the observation that it yields a mixture
of borneol and isoborneol by reduction with sodium and alcohol.

Camphene is formed much more readily by the removal of
water from isoborneol than from borneol ; this reaction is particu-
larly characteristic. When a solution of isoborneol in benzene is
heated with zine chloride for one hour, a quantitative yield of
camphene is obtained ; a result almost as favorable as this is pro-
duced by boiling isoborneol with dilute sulphuric acid for several
hours. Under these conditions pure borneol (m. p. 203° to 204°),
prepared from bornyl acetate, is not changed.

Semmler* has further shown that when isoborneol is heated

1Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 1.

2According to Semmler (Ber., 33, 3420), isoborneol gives a small as of

camphor on oxidation with dichromate and sulphuric acid.
3F, Semmler, Ber., 33, 774.

148 THE TERPENES.

with zine dust for half an hour at 220°, it is converted into a
small quantity of camphene, together with a larger amount of
isodihydrocamphene, C,,H,, (m. p. 85°) ; under similar conditions
borneol remains unchanged. From this it appears that isoborneol
is a tertiary alcohol, and borneol a secondary alcohol.

The acetic acid ester of isoborneol may be obtained from cam-
phene by the method given under the preparation of isoborneol.
Isobornyl formate can be prepared in a similar manner ; it is also.
formed by adding fifty grams of isoborneol to a mixture of one
hundred grams of formic acid (sp. gr. 1.22) and two grams
of sulphuric acid, and warming to 30°. The acetyl ester is pro-
duced by a like process, but at a somewhat higher temperature.
The esters may further be obtained by boiling isoborneol with
acid anhydrides.

Isobornyl formate is a liquid, boiling at 100° under a pressure
of 14mm., and has a specific gravity of 1.017 at 15°.

Isobornyl acetate is also a liquid, which boils at 107° at 13 mm.
pressure, and has the specific gravity 0.9905 at 15°.

The odors of these esters are like those of the isomeric bornyl
esters.

The readiness with which the hydroxyl-group in isoborneol
may be replaced by the ethoxyl- or methoxyl-groups is very
characteristic. While the corresponding derivatives of borneol
are prepared by treating its sodium salt with alkyl haloids, the
formation of ethers from isoborneol takes place on mixing and
warming an alcohol with isoborneol and sulphuric acid.

Methyl isobornyl ether, C,,H,,OCH,, is prepared by heat-
ing sixty grams of isoborneol with one hundred and twenty
grams of methyl alcohol and thirty grams of sulphuric acid.
After boiling for twenty to thirty minutes, the mixture be-
comes cloudy, two layers are formed, and, in the course of one
hour, the product is diluted with water. The resulting methyl -
ether boils at 192° to 193° (at 77° under a pressure of 15 mm.),
and has asp. gr. 0.9265 at 15°.

Ethyl isobornyl ether, C,,H,,OC,H,, is formed in an analogous
manner ; it boils at 203° to 204,° and has the sp. gr. 0.907 at
15°. According to Semmler,' this compound is also prepared by
boiling a mixture of camphene, alcohol, and sulphuric acid.

Methylene isobornyl ether, (C,,H,,O),CH,, is obtained by the
method adopted by Briihl for the preparation of methylene bornyl
ether ; like the latter, it melts at 167°. It is distinguished from
the bornyl derivative by its greatly diminished solubility in

1Semmler, Ber., 33, 3420.

ISOBORNYL PHENYLURETHANE.

149

petroleum ether and alcohol, and by its slight power of crystalli-
zation ; it separates in groups of fine crystals.

The compound of isoborneol with chloral is a liquid. The
bromal derivative is a solid, but does not crystallize well; it

melts at 71° to 72°.

Isobornyl phenylurethane, C.LH,NH-CO-OC,,H,,, is difficultly

benzene.

* soluble in petroleum ether, more readily in warm alcohol and
It melts at 138° to 139° (bornyl phenylurethane melts

at the same temperature), and yields isoborneol when warmed with

alcoholic potash.

The differences between isoborneol and derivatives, and borneol
and its compounds are rendered more apparent by the following

table :

Isoborneol.

Borneol.

Crystal form,

hexagonal, double refrac-
tion +,

hexagonal, double refrac-
tion —.

Melting point, 212°, 203° to 204°.
Boiling point, undetermined, 212°.
Solubility in benzene at | 1: 2.5 to 3, 1: 6.5 to 7.
°
,
Solubility in benzene at | 1:1.5 to 2, 1:4 to 4.5.
20°,
Solubility in petroleum | 1:4 to 4.5, zi 1:10 to 11.
ether at 0°,
Solubility in petroleum | 1: 2.5, 1:6.
ether at 20°,
Phenylurethane, m. p. 138°) . . | m. p. 138° 5 :
to 139°, | isoborneolis| to 139°, | borneol is
regenerated |______-_ | regenerated
- Chloral compound, liquid, by treat- m. p. 55° | by treat-
: ment with to 56°, ment with
alcoholic |—————— | _ alcoholic
Bromal compound, m. p. 72°, potash, ms ng potash.
? 0 Reid

Formy] ester,

liquid, b. p. 100°

liquid, b. p. 98° to 99°

(14 mm. ), (15 mm. ).
Acetyl ester, liquid, b. p. 107° m. p. 29°; b. p. 106° to
13 mm. ), 107° (15 mm. ).

Behavior towards zine
chloride or dilute sul-
phuric acid,

forms camphene,

unchanged.

Behavior towards sul-
phuric acid and methyl
or ethyl alcohol.

forms methyl] or ethy]
isoborny] ether,

does not yield ethers by
this treatment.

150 THE TERPENES.

Isobornyl chloride,’ C,,H,,Cl, is obtained when hydrogen chlo-
ride is led into an alcoholic solution of isoborneol. It melts at
150° to 152°, and is identical with camphene hydrochloride.

A brief statement regarding the rotatory powers of the more im-
portant derivatives of camphor is presented in the following.

According to Beckmann,’ camphor has the specific rotatory
power, [a],= +44.22°. The direction and degree of rotation
is not changed by heating camphor to high temperatures (230° to
250°), or by boiling it with alcohol or glacial acetic acid, or by
dissolving in concentrated sulphuric acid. |

The same investigator finds that camphoroxime prepared from
levo-camphor is dextrorotatory, whilst the oxime from dextro-
camphor is levorotatory. He gives these values for the rotatory
power of camphoroxime :

Dissolvedin 5 parts of alcohol, [a],=— 42.4° and + 42.51°,
“6120 6 & [aly = —41.38° and + 42.38°.

Camphoroxime hydrochloride (m. p. 162°) has the specific ro-
tatory power, [a], = — 43.98° and + 42.52°.

Borneol has a different rotatory power according to its origin ;
thus Beckmann* found the rotatory power of d-borneol to be
[a] = + 37.44°, and Haller* determined the rotatory power of
borneol regenerated from the crystalline acetate, [a] = + 37.63°.
Natural l-borneol has [¢] » = —37.74° (Beckmann’), and —37.77°

Haller’) ; a l-borneol occurring under the name of Ngai fén has
a)» = — 389° 25’ (Schimmel & Co.°),

According to Bertram and Walbaum,’ the rotatory power of
isoborneol changes under the influence of the sulphuric acid used
in its preparation. This substance further shows a change in
strength of its optical rotation when dissolved in different solvents.
Isoborneol obtained from the camphene of citronella oil has the
rotatory power :

Dissolved in alcohol, [a], = + 4.71°.
Dissolved in benzene, [a], = + 2.88°.

1A. Reychler, Ber., 29, 697; Bull. Soc. Chim., 15, 1896 (III.), 366; see
also Jiinger and Klages, Ber., 29, 544.

2Beckmann, Ann. Chem., 250, 352.

’Beckmann, Ann. Chem., 250, 353; Journ. pr. Chem. [II.], 55, 31.

*Haller, Compt. rend., 109, 30; 112, 143.

5Haller, Compt. rend., 108, 456; 109, 456.

5Schimmel & Co., Semi-Annual Report, April, 1895, 76.

TBertram and Walbaum, Journ. pr. Chem., 49, 14.

“oe
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~

ALDEHYDE FROM CAMPHENE GLYCOL. 151

4. CAMPHENE GLYCOL, C,,H,,(OH),.

Camphene glycol is closely allied to borneol ; it was obtained
by G. Wagner’ by the oxidation of camphene with potassium
permanganate.

Seventy grams of camphene dissolved in twenty-five grams

. of benzene are added to six liters of a one per cent. solution of

potassium permanganate. If the color of the permanganate is
entirely removed after four hours of constant agitation, the mixture
is allowed to stand for some time, and the clear alkaline solution
removed in a current of carbon dioxide by means of Zulkowsky’s
suction apparatus. The residue consisting of manganese oxides
is washed with water, and again shaken with four and one-half -
liters of a one per cent. solution of permanganate. After decol-
orization, the liquid is removed as above suggested, and the
manganese oxides are treated for a third time with three liters of
permanganate. The filtrates thus obtained are saturated with
carbonic anhydride, and extracted thirty times with benzene.
The benzene is then distilled off, and a small amount of cam-
phene which remains in the residue is driven over with steam ;
camphene glycol is only slightly volatile with steam, and after
the addition of potassium hydroxide to the aqueous residue it is
extracted with ether. On evaporation of the latter the solid
glycol is obtained, and repeatedly recrystallized from benzene.
It separates in prismatic needles, which melt at 192°. It is
very readily soluble in ether, alcohol, carbon bisulphide and
chloroform, sparingly in benzene; when thrown upon water it
rotates in the same manner as camphor. It melts when warmed
with water, and is only slightly soluble in hot water ; it sublimes
very readily when heated above 100°.

ALDEHYDE, C,,H,,O, FROM CAMPHENE GLYCOL.

When camphene glycol is heated with hydrochloric acid, it loses
one molecule of water, forming a solid substance which smells like
camphor ; it has the formula, C,,H,,O, and is characterized as an
aldehyde by its behavior towards fuchsinesulphurous acid and to-
wards an ammoniacal silver solution. Hydroxylamine reacts with
it, yielding a liquid compound ; bromine acts slowly upon its solu-
tion in chloroform, giving rise to substitution products. When it
is allowed to stand with water in the air, the water at once gives
an acid reaction, and the substance becomes liquid (Wagner').
(See camphenilanic acid, page 65.)

1G. Wagner, Ber., 28, 2311.

152 THE TERPENES.

This aldehyde is also formed in small quantities in the prepara-
tion of camphene glycol.

According to recent investigations of Bredt and Jagelki,’ it
seems probable that this aldehyde is identical with camphenilan
aldehyde (m. p. 70°), which is formed by the action of water on
the double compound of camphene with chromyl dichloride.

Pinene glycol, C,,H,,(OH),, is described by Wagner ; it is men-
tioned under pinene (see page 46).

5. CAMPHOL ALCOHOL, C,,H,,OH.

According to Errera,? if a solution of campholamine hydro-
chloride be warmed with silver nitrite, camphol alcohol, C,,H,,OH,
is produced, together with a hydrocarbon, C,,H,,. This alcohol
is a liquid having an agreeable odor, and boils at 203°.

Since campholamine contains the group, — CH,NH,, it would
be expected to yield a primary alcohol; Errera,*® however, de-
termined by the speed of the ester formation that camphol alcohol
is a tertiary alcohol.

6. CAMPHENONE, C,,H,,0.

Claisen and Manasse* prepared amidocamphor by reduction of

isonitroso-camphor ;
=NOH
C,H
8 KI

with zine dust and acetic acid; by treating amidocamphor with
nitrous acid, Angeli® obtained diazo-camphor,

N
C,H $6
8 ae 0

which, according to Curtius’ nomenclature, may be called mono-
ketazo-camphor-quinone or monoketazocamphadione. When this
substance is heated and the resultant product is distilled with
steam, camphenone, C,,H,,O, is formed. It has an odor similar
to that of camphor, and separates from petroleum ether in splendid,
colorless crystals, which melt at 168° to 170° (Angeli *).

1Bredt and Jagelki, Ann. Chem., 310, 112.

2Errera, Gazz. Chim., 22 [2], 114; Ber., 26, 21, Ref.

3Errera, Gazz. Chim., 23 [2], 497; Ber., 27, 126, Ref.

4Claisen and Manasse, Ann. Chem., 274, 88.

5Angeli, Ber., 26, 1718; Rimini, Gazz. Chim., 26 [2], 290.

6 Angeli, Gazz. Chim., 24 [2], 44 and 317; Ber., 27, 590, 797 and 892,
Ref.

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:
5

—

ISOCAMPHENONE. 153

Camphenone behaves as an unsaturated compound; it is im-
mediately oxidized by a permanganate solution, and is reduced to
camphor by the action of nascent hydrogen.

Camphenone hydrobromide,' C,,H,,O- HBr, is produced by treat-
ing camphenone with hydrogen bromide in a glacial acetic acid
solution; it is isomeric with monobromocamphor. It melts at
113°, is stable towards acids, but is converted into camphenone
by alkalis, and yields camphenonoxime on treatment with an alka-
line solution: of hydroxylamine.

Camphenone dibromide,' C,,H,,O- Br,, is formed by the addition
of bromine to a solution of camphenone in carbon bisulphide ; it
is isomeric with dibromocamphor, but is readily distinguished
from the latter by yielding monobromocamphenone on treatment
with alcoholic potash. It separates from alcohol or petroleum in
large crystals, and melts at 58° to 59°.

Monobromocamphenone, C,,H,,BrO, is obtained by treating
camphenone dibromide with alcoholic potash ; it forms large, well
defined crystals, melting at 70°.

Camphenonoxime,? C,,H,,NOH, is formed by the action of
hydroxylamine on camphenone; it crystallizes from petroleum
ether in tablets, and melts at 132°. It is isomeric with nitro-
sopinene, and melts at the same temperature as the latter. By
the action of mineral acids it is gradually converted into a nitrile.

Pernitrosocamphenone,’ C,,H,,N,O,, is prepared by the action
of nitrous acid on camphenonoxime ; it melts at 47°, is insoluble
in acids and alkalis, and does not give the Liebermann’s reaction.

Pernitrosocamphenone dibromide (dibromopernitrosocamphor),
C,,H,,N,O,-Br,, is produced by the addition of bromine to a chlo-
roform solution of pernitrosocamphenone. It crystallizes from
petroleum and melts at 133°.

Isocamphenone, C,,H,,O.— When pernitrosocamphor, C,,H,,N,O,
(obtained by the action of nitrous acid on camphoroxime), is dis-
solved in a glacial acetic acid solution of dry hydrogen bromide,
and is then treated with bromine, bromopernitrosocamphor, C,,H,,-
BrN,O, (m. p. 114°), is formed; this is converted into isobromo-
pernitrosocamphor, C,,H,,BrN,O, (m. p. 67°), by the action of di-
lute alcoholic potash. When the latter compound is treated with
cold, concentrated sulphuric acid, isocamphenone is obtained ; it
separates from petroleum in yellowish crystals, melts at 92°, and
soon resinifies in the air. Its oxime melts at 170°.

1Angeli and Rimini, Atti. d. R. Acc. d. Lincei Rudct., 1895 [1], 390;
Gazz. Chim., 26 [2], 34 and 45.

2Angeli, Gazz. Chim., 24 [2], 44 and 317; Angeli and Rimini, Gazz. Chim.,
26 [2], 34 and 45; Ber., 28, 1077.

154 THE TERPENES.

7. PINOCAMPHONE, C,,H,,0.

This ketone, which is isomeric with camphor, is formed as a
by-product in the preparation of pinylamine, C,,H,,NH,, from
nitrosopinene, C,,H,,NOH. Wallach’ observed the formation of
this ketone during his first researches on the reduction-products of
nitrosopinene, but it was not until the year 1898 that he pub-
lished a detailed account of its method of preparation and its
properties.”

Pinocamphone is prepared by the following method. Five
grams of nitrosopinene are dissolved in forty cc. of warm glacial
acetic acid, and, after diluting with sufficient water to pro-
duce a slight cloudiness, the solution is treated with a large excess
of zinc dust. After the first violent reaction has ceased, the
mixture is heated in a reflux apparatus on the water-bath for
three or four hours. The excess of zinc is then removed by fil-
tration, the filtrate is distilled with steam, and the distillate is
extracted several times with ether ; the ethereal solution is dried
with solid potash, the ether is distilled off, and the residue is
fractionated in vacuum. ‘The yield of pinocamphone is over
twenty per cent. of the nitrosopinene employed.

The odor of pinocamphone is somewhat similar to that of tur-
pentine, but on warming it suggests that of peppermint oil. It
boils at 211° to 213°, has the specific gravity 0.959, and the re-
fractive index, ny = 1.47273, at 21°; its molecular refraction

is 44.44, while that calculated for the compound, C,,H,,O, is

44.11.

Pinocamphonoxime, C,,H,,NOH, is readily obtained, and is char-
acterized by its splendid power of crystallization. It is volatile
with steam, crystallizes in large, transparent plates, and melts at
86° to 87°. On reduction with sodium and alcohol, it yields
pinocamphylamine, C,,H,,NH,, which is a liquid; it rapidly
absorbs carbon dioxide, forms a carbamide (m. p. 204°), and an
acetyl derivative (m. p. 120°).

Pinocampholenonitrile, C,,H,,N.—Pinocamphonoxime is not at-
tacked by boiling dilute sulphuric acid. When the oxime is
boiled for a considerable time with concentrated sulphuric acid

(one part acid to one part water), a small proportion is converted

into a nitrile, while much of the oxime remains unaltered. The
nitrile is obtained by distilling the reaction-product with steam.

1Wallach, Ann. Chem., 268, 210.
2Wallach, Ann. Chem., 300, 287.
3Wallach, Ann. Chem., 313, 345.

FENCHONE. 155

The nitrile’ is an oil, having an odor similar to that of campho-
lenonitrile, and is volatile with steam; it boils at 224° to 226°.
It is converted into pinocampholeniec acid, C,,H,,O,, by heating
with alcoholic potash ; this acid yields an amide melting at 116°.

Pinocamphone semicarbazone melts at 199° to 200°.

Wallach is inclined to regard pinocamphone, C,,H,,O, as the
dihydro-derivative of an unknown ketone, C,,H,,O, which cor-
responds with nitrosopinene, C,,H,,NOH.

A ketone, C,,H,,O, isomeric with pinocamphone, is formed when
nitrosopinene dibromide is reduced with zinc and acetic acid in
exactly the same manner as described above. This compound is
an oil, having an odor similar to that of carvone. It yields an
oxime, which crystallizes from dilute alcohol in needles, and melts
at 113° to 114°.

The properties of this isomeric ketone and of its oxime re-
semble so closely those of inactive dihydrocarvone, that Wallach
is inclined to consider the ketone as identical with inactive dihy-
drocarvone.

8. PINOCAMPHEOL, C,,H,,OH.

This alcohol, isomeric with borneol, is prepared by reducing
pinocamphone with sodium in aqueous ether according to Beck-
mann’s method of reducing camphor to borneol.

It is a viscous liquid, having the odor of terpineol and turpen-
tine. It boils at 218° to 219°, has the specific gravity 0.9655,
and the refractive index, n»= 1.48612, at 20°. When it is
heated with zine chloride, it loses water and yields products among
which cymene has been identified.

Pinocamphyl phenylurethane,

/NHCG,H;
co
\OC, >Hi:

forms a crystalline mass, and melts at 98°.

9, FENCHONE, C,,H,,0.

Fenchone occurs in nature in a dextrorotatory and a levorota-
tory modification, and in its total behavior shows the greatest sim-
ilarity to camphor. Dextro-fenchone is present in fennel oil,’
while levo-fenchone forms a constituent of thuja oil.*

Wallach, Ann. Chem., 313, 345.
2Wallach and Hartmann, Ann. Chem., 259, 324.
3Wallach, Ann. Chem., 272, 102.

156 THE TERPENES.

The fractions boiling between 190° and 195° of fennel oil and
thuja oil consist almost wholly of fenchone. Its purification is
easily accomplished, since fenchone is much more stable towards
oxidizing agents than the substances accompanying it. However,
the compounds occurring with fenchone in fennel oil differ in
character and in quantity from those found in thuja oil, hence the
two oils cannot be treated in the same manner.

Preparation of Dextrorotatory Fenchone.'—The fraction of fennel
oil boiling at 190° to 195° contains considerable quantities of
anethol and other impurities, even after repeated distillations.
Two hundred grams of this fraction are heated with three times
its amount of ordinary concentrated nitric acid in a large flask,
connected with a reflux condenser, over a free flame. A vigorous
reaction takes place, accompanied by evolution of nitrogen oxides.
At this point, it is well to somewhat diminish the heat in order
to prevent a too violent action. The mixture is then warmed
until the fumes, which are at first reddish brown in color, are
light colored. It is then allowed to cool; the contents of the
flask are poured into water, and the resulting oil is separated.
This oil is washed with a solution of sodium hydroxide, distilled
with steam, and the fenchone obtained in the distillate is dried
with potash; the product is now quite pure. It is then cooled
in a freezing mixture and brought to crystallization by the addi-
tion of a small crystal of pure fenchone. Large crystals of pure
fenchone separate, and are filtered from the residual oil.

The fraction boiling at 190° to 195° of thuja oil contains a
much smaller quantity, about twenty to twenty-five per cent., of
fenchone. Thujone isthe chief constituent of this fraction.

Pure levorotatory fenchone is prepared by one of three follow-
ing methods (Wallach’).

1. Oxidation with Nitric Acid.

To eighty cc. of hot concentrated nitric acid contained in a capa-
cious flask provided with a reflux condenser (the tube of the
condenser should be sealed onto the flask), twenty cc. of the above-
mentioned fraction of thuja oil are added drop by drop. After
all of the oil has been introduced, the mixture is boiled for an
hour, and then distilled with steam ; the resulting oil is washed -
with sodium hydroxide, again distilled with steam, and the pure
levo-fenchone is crystallized by the method suggested above.

1Wallach, Ann. Chem., 263, 130.
2Wallach, Ann. Chem., 272, 102.

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FENCHONE. 157

2. Oxidation with Permanganate.

Levorotatory fenchone and thujaketonic acid may be very con-
veniently prepared at the same time. For this purpose, one hun-
dred and thirty grams of the fraction of thuja oil boiling at 190°
to 200° are shaken with a solution of three hundred and ninety
grams of potassium permanganate in five liters of water, until the
permanganate solution is decolorized ; some form of shaking ma-
chine is employed to constantly agitate the mixture. The un-
changed oil is distilled with steam, separated and treated with hot
nitric acid according to method 1. By this operation larger quan-
tities of levo-fenchone may be obtained in one treatment.

3. Treatment with Dilute Sulphuric Acid.

The thujone in thuja oil may be more readily separated from
levorotatory fenchone by heating the fraction of this oil boiling
at 190° to 200° with dilute sulphuric acid (one volume of concen-
trated acid with two volumes of water). Thujone is so converted
into isothujone, which boils 30° higher than thujone, while fen-
chone remains unchanged ( Wallach’).

Fenchone is further obtained by boiling fenchyl alcohol with
three times its amount of nitric acid? The product thus formed
has the same optical rotation, respecting direction and power, as
the fenchone from which the alcohol is prepared by reduction.

PROPERTIES.*—The properties of dextro- and levo-fenchone
agree completely with the exception of the opposite rotatory
powers. Wallach found the specific rotatory powers as follows:

Dextro-fenchone (chemically pure) = + 71.97°.

Levo-fenchone (not absolutely pure) = — 66.94°.

Inactive fenchone,* prepared by mixing equal parts of dextro-
and levo-fenchone, has the same properties as its active compo-
nents, but its derivatives, however, often differ considerably from
the corresponding active compounds in melting points, forms of
crystals and solubilities. Inactive fenchone bears the same rela-
tion to its active constituents as racemic acid does to the dextro-
and levo-tartaric acids.

Pure fenchone is an oil, smells like camphor, boils at 192° to
193°, and has the sp. gr. 0.9465 at 19°; its refractive index is
Ny = 1.46306 at 19°, corresponding to a molecular refraction of

Wallach, Ann. Chem., 286, 103.
2Wallach, Ann. Chem., 263, 146.
3Wallach, Ann. Chem., 263, 131; 272, 103.
4Wallach, Ann. Chem., 272, 107.

158 THE TERPENES.

44.23 while the calculated value for a compound of the compo-
sition, C,,H,,O, containing no ethylene linkage, is 44.11. It
solidifies at a low temperature, and melts at 5° to 6°.

Fenchone is a saturated compound. It combines with bromine
in a cold petroleum ether solution, yielding a red, crystalline, un-
stable additive product which is reconverted into fenchone on
treatment with alkalis. Substitution takes place if bromine acts
upon fenchone for a long time, or at a high temperature.

Fenchone is quite readily dissolved by cold concentrated hy-
drochloric acid or sulphuric acid, and is thrown out of this solu-
tion on the addition of water.

When it is warmed with strong sulphuric acid at about 80°,
sulphur dioxide is given off and acetoxylene,C,,H,,O [CH, : CH, :
CH,CO = 1:2:4], is formed; this is an oil, smelling somewhat
of cinnamon. It boils at 131° at 20 mm. pressure, yields an
oxime, melting at 86° to 87°, and is converted into para-aylic acid,
C,H,,O,, by oxidation (Marsh ’).

With fuming nitric acid fenchone forms a clear mixture without
any apparent reaction, and is precipitated unchanged by water.
It may even be boiled with fuming nitric acid without visible
change ; by long continued boiling it is acted upon by nitric acid,

being converted into a mixture of organic acids. Thus, ac- |

cording to Gardner and Cockburn,’ when fenchone is heated
with concentrated nitric acid on the water-bath for six days,
it is oxidized to isocamphoronic acid, C,H,,O, (m. p. 163° to
164°), dimethyltricarballylic acid, C,H,,O, (m. p. 152°), dimeth-
ylmalonic acid, C,H,O, (m. p. 190°), isobutyric acid, and acetic
acid ; in addition to these acids a nitrofenchone, C,,H,,O-NO,, is
formed. The latter is an oil, which boils at 146° to 151° under
14 mm. pressure, and, on reduction with stannous chloride, yields
an amine.

Fenchone is more vigorously attacked by heating with three
times its amount of fuming nitric acid in a sealed tube at 120°;
hydrocyanie acid is one of the products of this reaction.

Potassium permanganate oxidizes fenchone to a mixture of
acetic, oxalic and dimethylmalonic acids ( Wallach’).

When phosphorus pentachloride is allowed to act upon fen-
chone for six weeks in the cold, and the product is subsequently
treated with water, chlorofenchene-phosphoric acid, C,,H,,CIPO-
(OH), melting at 196°, a- and f-chlorofenchene hydrochlorides,

1J. E. Marsh, Journ. Chem. Soc., 75, 1058; compare with Claus, Journ. pr.
Chem., 41 (II.), 396; Armstrong and Kipping, Journ. Chem. Soc., 63, 75.

2Gardner and Cockburn, Journ. Chem. Soc., 73, 708.

3Wallach, Ann. Chem., 263, 134.

i

Siete Spee ee,

aa Sohne — ©

TRIBROMOFENCHONE. 159

C,,H,,Cl,, and chlorofenchene, C,,H,,Cl, a solid, boiling at 80° to
83° under 16 mm. pressure, are produced.’

Bromofenchone,’ C,,H,,OBr, is formed by heating fenchone with
bromine for twenty hours at 100° in a sealed tube; it is a color-
less oil which boils at 131° to 134° under 18 mm. pressure, has
a faint camphor-like odor, a sp. gr. 1.348 at 12°, a refractive

index 1.51013, and arotation + 11.6° in a 100 mm. tube. It is
* not readily volatile with steam, and yields neither an oxime nor a
semicarbazone. Fenchone is regenerated by heating the com-
pound with zine dust and acetic acid.

When bromofenchone is heated with an excess of alcoholic
potash, a-fencholenic acid, C,,H,,O,, is produced, identical with that
obtained by Wallach ; when cooled with liquid air, it crystallizes.
An isomeric compound,’ C,,H,,O,, is formed by dissolving the
acid in concentrated sulphuric acid and pouring the solution on
ice ; it crystallizes from light petroleum in leaflets, melts at 77°,
is not soluble in solutions of sodium carbonate or hydroxide, and
does not decolorize solutions of permanganate. (See “ Biological
Oxidation of Fenchone.” Rimini, Atti. Real. Accad. Lincei,
1901 [V.], 10 (1.), 244.)

Tribromofenchone,? C,,H,,OBr:Br,, is obtained by gradually
adding bromine to a solution of fenchone in phosphorus tri-
chloride ; it is a yellow oil, boils at 181° to 186° under 18 mm.
pressure and darkens in the air.

When tribromofenchone is boiled with zinc dust and acetic
acid, it yields a crystalline compound, C,,H,,Br, melting at 115°
to 116° ; it has a camphor-like odor, and in general properties re-
sembles the chlorofenchene above mentioned. It sublimes readily
and decolorizes permanganate.

- Tetrahydrofenchene,* C,,H,,, results when fenchone is heated
with phosphorus and hydriodic acid ; the same hydrocarbon is ob-
tained from fenchy] alcohol under analogous conditions.

That fenchone is a ketone follows from the formation of
fenchonoxime and fenchyl alcohol. On heating fenchone with
ammonium formate according to Leuckart’s method, fenchyl-
amine, C,,H,NH,, a base isomeric with bornylamine, is
formed.

It differs from camphor in that it does not form an oxymeth-
ylene compound.°

1Gardner and Cockburn, Journ. Chem. Soc., 7/7, 1156; 73, 704.
2Ozerny, Ber., 33, 2287; see Balbiano, Gazzetta, 30 [II.], 382.
8Czerny, Ber., 33, 2287.

*Wallach, Géttinger Nachrichten, 1891, 309; Ann. Chem., 284, 326.
5Wallach, Ber., 28, 34.

160 THE TERPENES.

The behavior of fenchone towards phosphorus pentoxide is of
especial interest in showing the resemblance of the reactions of
fenchone and of camphor. According to Wallach,’ twenty grams
of fenchone and thirty grams of phosphorus pentoxide were well
mixed in a small, round flask, and, after a further addition of
thirty grams of phosphorus pentoxide, the mixture was heated
for thirty minutes in a paraffin-bath at 115° to 130°. After
cooling, water was carefully added and the resulting oil identified
as meta-cymene, boiling at 175° to 176°. A comparison was
made of this cymene with meta-cymene isolated by Kelbe from the
distillation products of colophonium and resin oil, and they were
found to be identical.

Since para-cymene is formed by the action of phosphorus pen-
toxide on camphor, and nearly all of the properties of cam-
phor closely resemble those of fenchone, it is probable that these
two substances bear the same relation to each other that a para-
compound does to a meta-compound.

It may also be mentioned that by oxidation of dextrorotatory
and inactive fenchyl alcohols, obtained by Bouchardat and La-
font” by the action of benzoic acid and other acids on French
(levorotatory) turpentine, levorotatory and inactive fenchones
are obtained ; the former is the optical antipode of d-fenchone
prepared from oil of fennel. This synthetically prepared 1-fen-
chone forms an oxime (m. p. 161° to 163°), but it is produced
less readily than that obtained from the fenchone prepared from
oil of fennel.

Fenchone does not react with alkaline bisulphites.

Fenchone semicarbazone,’ C,,H,,-N-NH-CO-NH,, cannot be
prepared directly from fenchone and a semicarbazide solution.
It is formed, however, by gently heating pernitrosofenchone,
C,,H,,N,O,, with semicarbazide acetate on the water-bath. It
separates from alcohol in white crystals, and melts at 186°
to 187°.

Fenchonoxime, C,,H,,NOH, is conveniently prepared in small
quantities by the following method (Wallach*). To five grams of
fenchone dissolved in eighty ec. of absolute alcohol, a solution of
eleven grams of hydroxylamine hydrochloride in eleven grams of
hot water and six grams of pulverized potash are added. The spar-
ingly soluble oxime separates in the course of one or two days by
the gradual evaporation of the alcohol.

1Wallach, Ann. Chem., 275, 157.

2Bouchardat and Lafont, Compt. rend., 126, 755.
3Rimini, Gazz. Chim., 30 (I.), 600.

4Wallach, Ann. Chem., 284, 324; 272, 104.

ee ee

ee

s
.
y

FENCHONOXIME ANHYDRIDE. 161

For the preparation of larger quantities of fenchonoxime,
Wallach employs the following method. One hundred grams of
fenchone are dissolved in four hundred grams of absolute alcohol
and treated with a warm solution of eighty grams of hydroxyl-
amine hydrochloride in eighty grams of water. The solution is
then rendered alkaline by the addition of fifty grams of potassium
hydroxide dissolved in fifty grams of water; the potassium chlo-

- ride is filtered off, and the filtrate boiled for a few hours on the

water-bath. A large quantity of the oxime separates out on cool-
ing. An additional amount may be obtained by warming the
mother-liquor, and precipitating with water.’

Fenchonoxime crystallizes from alcohol in fine needles, and from
ethyl acetate or ether in well formed, monoclinic*® crystals, which
melt at 161° when heated rapidly.* It is volatile with steam, and
boils at 240° with slight decomposition (elimination of water). It
is insoluble in sodium hydroxide.

The oxime of dextro-fenchone is dextrorotatory,’ [a], =
52.54° ; that obtained from levo-fenchone is levorotatory.

Inactive fenchonoxime is formed by mixing the ethereal solu-
tions of equal parts of dextro- and levorotatory oximes ; it sepa-
rates in crystals which differ in form from those of the active
modifications, and melt slightly lower than these, at 158° to
160°.

Wallach and Hartman obtained fenchonoxime hydrochloride by
precipitating an ethereal solution of the dextro-oxime with hy-
drochloric acid ; it melts at 118° to 119°. :

Fenchylamine, C,,H,,NH,, analogous to bornylamine, is pre-
pared by reducing fenchonoxime with sodium and alcohol.

Fenchonoxime anhydride,® C,,H,,N (u- and §-fencholenonitrile,
C,H,, - CN), is formed very easily and quickly by the action of de-
hydrating agents on fenchonoxime. When the oxime is dissolved
in warm, dilute sulphuric acid, a clear solution is at first obtained,
but if this be heated to a higher temperature, fenchonoxime anhy-
dride separates at once as an oil, which may be readily distilled
with steam,

1Wallach, Ann. Chem., 263, 136.

2For preparation of fenchonoxime, see also Rimini, Gazz. Chim., 26 (IL),
502.

3Zander, Ann. Chem., 259, 327.

4Mahla and Tiemann (Ber., 29, 2807) give the melting point of the
active modifications at 163°; Rimini (Gazz. Chim., 26 (II.), 502) finds
them to melt at 165°.

5Wallach and Binz, Ann. Chem., 276, 317; 272, 104.

6Wallach and Hartmann, Ann. Chem., 259, 328; Wallach, Ann. Chem.,
263, 137.

11

162 THE TERPENES.

The anhydride prepared from dextro-fenchonoxime is dextro-
rotatory, [a] p = + 43.31°. It boils at 217° to 218°," has a spe-
cific gravity 0.898 and the refractive power, n, = 1.46108, at
20°.

Although fenchone and fenchonoxime are saturated compounds,
the anhydride is unsaturated, and forms a liquid bromide when
treated with bromine ; it also combines with hydrobromic and hy-
driodic acids, forming the solid, but unstable, addition-products,
C,,H,,N-HBrandC,,H,,N-HI. These two compounds can only
be crystallized from alcohol when great care is taken ; the hydro-
bromide melts at 60°, and hydriodide at 54° to 55°.

Hydrochlorofenchonoxime anhydride, C,,H,,N-HCl, is more stable
than the hydrobromide and hydriodide, and is prepared by shak-
ing the anhydride with concentrated hydrochloric acid; after a
short time the product becomes solid, is pressed on a porous plate,
and recrystallized from petroleum ether. The pure hydrochloride
melts at 57° to 58°, and decomposes into its constituents on boil-
ing with water or alcohol (Wallach’). -

Fenchonoxime anhydride is to be regarded as a nitrile,
C,H,,CN, since it may be converted into a- and f-fencholenic acids,
C,H,,COOH, and a-fencholenamide; the latter is identical with
a-isofenchonoxime.

When it is reduced with sodium and alcohol, an unsaturated
base, fencholenamine,* C,,H,,NH.,,, is formed ; this amine is isomeric
with camphylamine.

a-Isofenchonoxime, C,,H,,NO (a-fencholenamide, C,H,,CONH,).
The transformation of fenchonoxime anhydride into the corre-
sponding acid amide, and more especially into the acid itself, is
effected much more slowly than the like transformation of camphor-
oxime anhydride into a-campholenamide and a-campholenic acid.

a-Isofenchonoxime is prepared by warming thirty grams of
fenchonoxime anhydride with a solution of 130 grams of potas-
sium hydroxide in 450 cc. of absolute alcohol and twenty ce. of
water for four or five days. A small quantity of ammonia is
constantly given off, thus forming fencholenic acid, but the greater
part of the anhydride is converted into a-isofenchonoxime. The
solution is diluted with water, and the alcohol is removed by dis-
tillation ; on cooling, yellowish, crystalline leaflets are obtained,
which are purified by boiling with animal charcoal and reerystal-
lizing from alcohol. It melts at 113° to 114°, and dissolves in

1According to Cockburn (Journ. Chem. Soc., 75, 503), it boils at 214° to
219°.

2Wallach, Ann. Chem., 269, 330.

3Wallach and Jenkel, Ann. Chem., 260, 369.

0-FENCHOLENIC ACID. 163

alcohol, ether and acids ; it may be reprecipitated from an acid
solution by alkalis (Wallach *).

a-Fencholenic acid, a-isofenchonoxime and a-fencholenonitrile,
which is produced by gently warming a-isofenchonoxime with
phosphoric anhydride, are unsaturated compounds. The a-isox-
ime is optically active.

When the solutions of equal quantities of dextro-and levo-
a-isofenchonoxime are mixed, an inactive modification is formed,
which melts at 98° to 99°.

If the a-isoxime be reduced in an alcoholic solution with
sodium, a-fencholenic acid and a-fencholenamine are formed, to-
gether with isofencholeny! alcohol (see page 176).

$-Isofenchonoxime,’ C,,H,,NO, is a saturated compound, and is
obtained when a-isofenchonoxime is boiled for several hours with
dilute sulphuric acid. By this treatment the a-isoxime is grad-
ually dissolved, and when the cold solution is neutralized with
alkali, £-isofenchonoxime is precipitated as a white, crystalline
substance, which is more readily soluble in hot water than the
isomeric a-compound. It is readily soluble in alcohol, from
which it may be recrystallized ; it melts at 137°, has pronounced
basic properties and is probably a lactam. (See dihydrofencho-
lenic acid lactam.)

By the oxidation of a sulphuric acid solution of the f-isoxime
with permanganate, dimethylmalonic acid is formed ; therefore,
it has in all probability the same atomic structure as fenchone.

f-Isofenchonoxime is optically active; an inactive modifica-
tion may be obtained, and melts at 160° to 161°.

The hydrochloric acid salt is prepared by precipitating an ethereal
solution of the f-isoxime with hydrogen chloride ; it soon loses
hydrochloric acid by standing in the air.

The sulphate, obtained by treating the ethereal solution of the
$-isoxime with concentrated sulphuric acid, forms brilliant needles.

a-Fencholenic acid,*® C,H,,COOH, is formed, as indicated above,
by the saponification of fenchonoxime anhydride or of a-isofen-
chonoxime with alcoholic potash ; it is obtained from the alkaline
solution, from which some unchanged «a-isofenchonoxime also
erystallizes. For the complete separation of the latter, the alka-
line solution is shaken with ether, and then evaporated to such a
degree of concentration that the liquid separates into two layers;
the upper, dark-colored layer, which contains the fencholenic acid
salt, is separated from the lower one, consisting for the most part

1Wallach, Ann. Chem., 269, 332; 259, 330; 315, 273.

2Wallach, Ann. Chem., 269, 332; 284, 333.
3Wallach, Ann. Chem., 269, 334; 259, 330.

164 THE TERPENES.

of potassium hydroxide, and is acidified with sulphuric acid after
proper dilution with water. The liquid a-fencholenic acid is com-
pletely removed from the acid solution by means of ether, and is
distilled in a current of hydrogen. It boils at 260° to 261°, and
has the specific gravity 1.0045 at 16°; its coefficient of refraction
is 1.4768 at 16°, corresponding to the molecular refraction 47.24.

By the action of sodium hypobromite on the cold solution of sodium
a-fencholenate, a brominated lactone’ is formed, which melts at 76°.

Silver a-fencholenate, C,,H,,O,Ag, is sparingly soluble in water
and alcohol. The salts of the alkali metals and of the alkaline
earths are not characteristic. Ammonium a-fencholenate yields
a-isofenchonoxime (a-fencholenamide), when heated in a sealed
tube at 205° to 210°.

a-Fencholenic acid is unsaturated, and when shaken with hydro-
gen iodide or chloride it forms solid addition-products.

Hydrochlorofencholenic acid, C,,H,,ClO,, prepared by shaking
a-fencholenic acid with concentrated hydrochloric acid, separates
from petroleum ether in small, hard crystals, and melts at 97° to
98°. The hydrobromide,” C, H, ,BrO,, melts at 96° to 100°.

a-Fencholenic acid is immediately oxidized by a cold solution of
potassium permanganate with the production of an acid, which
has a syrup-like consistency.

The electrical conductivity of a-fencholenic acid has been de-
termined by Binz.*

When sodium a-fencholenate is distilled with soda-lime, it gives
a complicated mixture of hydrocarbons and compounds containing
oxygen (Wallach).

A saturated hydrocarbon is formed when a-fencholenic acid is
reduced by heating with phosphorus and concentrated hydriodic
acid at 180° to 200°; this compound distills almost completely at
138° to 145°, and the analyses and determinations of its vapor
density indicate that it consists chiefly of dihydrofencholene, C,H,,.

Dihydrofencholene boils at 140° to 141°; its specific gravity
is 0.790 and refractive power, ny = 1.43146, at 20°. The same
hydrocarbon is also obtained by reducing fenchonoxime anhydride
in like manner.

The formation of this hydrocarbon shows that fencholenic acid
and fencholenonitrile possess a closed carbon chain.

According to the investigations of Cockburn,* a second series

1Wallach, Ann. Chem., 315, 273.

2Cockburn, Journ. Chem. Soc., 75, 506.

sBinz, Ann. Chem., 269, 338.

4Cockburn, Journ. Chem. Soc., 75, 501. Wallach has also confirmed these
observations, see Ann. Chem., 315, 273.

-FENCHOLENIC ACID. 165

of isomeric substances is derived from fenchonoxime ; Cockburn
designates these as beta~-compounds.

f-Fencholenonitrile, C,H,,-CN.—According to Cockburn, the
fencholenonitrile, prepared as described under fenchonoxime
anhydride by the action of dilute sulphuric acid on fenchonoxime,
is a mixture of the a- and -nitriles, and boils at 214° to 219° ;
on saponification it yields a- and f#-fencholenic acids. The pure
a-nitrile may be prepared from a-isofenchonoxime (m. p. 113° to
114°) ; it boils at 211° to 212°, has the sp. gr. 0.9136 at 15.6°,
and the specific rotatory power [a@]p)= + 28.98°. On boiling
with alcoholic potash, it is readily converted into the a-amide
(a-isofenchonoxime, m. p. 113° to 114°), but only with difficulty
into the liquid a-fencholenic acid.

Pure -fencholenonitrile, prepared from the f-amide by warm-
ing with phosphorus pentoxide, is a colorless liquid, boils at 217°
to 219°, has the specific gravity 0.9203 at 15.6°, and the speci-
fic rotatory power, [a] p = + 43.66°. Itis quantitatively and very
readily converted into £-fencholenic acid on hydrolysis, but ap-
parently cannot be changed into the f-amide by the action of
alcoholic potash.

f-Fencholenamide, C,H,,-CONH,.—By the hydrolysis of the
mixture of nitriles, formed in the dehydration of fenchonoxime,
only the a-amide melting at 113° to 114° can be obtained.
The f-amide is produced, however, by heating the ammonium
salt of 6-fencholenic acid ina sealed tube, at 180°, for five hours ;
it is readily soluble in ether and alcohol, and crystallizes from a
mixture of alcohol and light petroleum in soft, silky needles, melt-
ing at 86.5° to 87.5°.

f-Fencholenic acid,’ C,H,,-COOH, is prepared by the hydrolysis
of the mixture of a- and f-nitriles by heating with alcoholic pot-
ash for two and one-half days; all of the f-nitrile is thus con-
verted into the f-acid while only a small quantity of the a-acid
is produced, owing to the difficulty with which the a-amide is
saponified, The a-amide which is formed is separated, and can
be used for the preparation of the pure a-acid. The yield of
the f-acid is about 55 to 60 per cent., and of a-amide 35 per cent.
of the theoretical, the remainder being the a-acid.

f-Fencholenic acid is purified by recrystallization from light
petroleum ; it melts at 72° to 73°, boils without decomposition at
259° to 260°, and has the specific rotatory power, [a] p= +
19.64°. It is readily soluble in alcohol, ether, and acetone, less
so in benzene and glacial acetic acid. It is an unsaturated acid,

1Cockburn, Journ. Chem. Soce., 75, 503; see Wallach, Chem. Centr., 1899
(1I.), 1052; Nachr. k. Ges. Wiss. Géttingen, 1899, No. 2.

166 THE TERPENES.

and immediately decolorizes bromine and permanganate solutions.
Its salts of the alkali metals are not very characteristic, but the
salts of the alkaline earths are well defined, crystalline com-
pounds, thus differing from the corresponding salts of the a-acid.

B-Fencholenic acid yields a brominated lactone, melting at 80°,
by the action of sodium hypobromite on the cold solution of the
sodium salt.

According to Cockburn, pure a-fencholenie acid, prepared by
the hydrolysis of the a-amide, melting at 113° to 114°, boils
with slight decomposition at 254° to 256°, has the specific gravity
1.0069 at 16°, and the specific rotatory power, [4], = + 30.73°.

Hydrobromo-f-fencholenic acid, C,,H,,BrO,, is formed during
the action of bromine on a solution of the f-acid in petroleum
ether, cooled by a freezing mixture. It crystallizes from light
petroleum in long, thin needles, and melts without decomposition
at 80° to 81°.

The Action of Nitrous Acid upon Fenchonoxime.”

According to Mahla and Tiemann, when an ethereal solution of
fenchonoxime is treated with nitrous acid, two compounds are
formed ; one is insoluble in ether, and is termed fenchonimine ni-
trate, C,,H,,N-HNO,, melting at 152°, while the other remains in
the ethereal liquid after separation of the nitrate, and is called
Jenchonitrimine, C,,H,,.N,O,, melting at 58°.

According to Angeli and Rimini, when a dilute hydrochloric
acid solution of fenchonoxime is treated with sodium nitrite, per-

nitrosofenchone, C,,H,,N,O,, is obtained ; it crystallizes in trans-

parent scales, melts at 66° to 67°, and is probably identical with
Tiemann’s fenchonitrimine. It is converted into fenchone by
heating with alcoholic potash, but when treated with cold alcoholic
potash or ammonia, it is changed into csopernitrosofenchone, ©,,-
H,,N,O,; this compound melts at 88°. Pernitrosofenchone and
its isomeride are both converted into isocamphor, C,,H,,O, by
treatment with concentrated sulphuric acid ; isocamphor is an oil,
boiling at 216°, and yields an oxime (m. p. 106°), and a semicar-
bazone(m. p. 215°). When pernitrosofenchone and semicarbazide
acetate are heated on the water-bath, fenchone semicarbazone (m.
p- 186° to 187°) is obtained.

Fenchimine, C,,H,,: NH, results by the action of twenty-five

per cent. aqueous ammonia on fenchonitrimine, C,,H,,N,O,. It

1Wallach, Ann. Chem., 315, 273.

2Mahla and Tiemann, Ber., 29, 2807; Angeli and Rimini, Gazz. Chim., 26
{II.], 228; Rimini, Gazz. Chim., 26 [I1.], 502; 30 [1.], 600.

3F, Mahla, Ber., 34, 3777.

OXYDIHYDROFENCHOLENA MIDE, 167

boils at 83° (15 mm.), has the specific rotatory power, [a], = +
76.3°, at 19.5° (10 cm. tube), sp. gr. is 0.9322 at 11.5°, re-
fractive index is ny = 1.47809 at 17°, and the molecular re-
fraction 45.78. It is a strong base and forms crystalline salts ;
the picrate forms splendid crystals and melts at 202° ; the hydro-
chloride melts at 278°, and on heating to 180° for eight hours is
decomposed with the formation of cymene. Methylfenchimine
iodide forms well defined crystals.

When a current of dry air is passed through warm, pure
fenchimine, it is converted into dihydrofencholenonitrile and oxy-
dihydrofencholenonitrile.

Dihydrofencholenonitrile, C,H,,-CN, is formed by leading a cur-
rent of dry air through fenchimine heated in an oil-bath at 105° ;
after the action has continued for thirty-six to forty-eight hours,
the nitrile is distilled over with steam, and is obtained in a yield of
about forty per cent. The oxy-nitrile remains in the distilling flask.

Dihydrofencholenonitrile boils at 98° to 104° (23 mm.), has
the sp. gr. 0.8951 at 16.5°, np = 1.44743 at 17.5°, M = 45.15,
and [a], = + 25° at 19° (10 em. tube). It is insoluble in
water and is saponified only with difficulty. When boiled vigor-
ously for eight hours with thirty per cent. alcoholic potash, it is
changed into a small quantity of the corresponding acid and a
large proportion of the amide. On distilling off the alcohol, the
amide is found in the residue and is purified by recrystallization
from dilute alcohol.

Dihydrofencholenamide, C,H,,- CONH,, is formed as above men-
tioned by hydrolysis of the nitrile. It is crystallized from dilute
alcohol and then from ethyl acetate ; it melts at 130.5°, and sub-
limes slowly at 107°.

Dihydrofencholenic acid, C,H,,-COOH, is obtained by the hy-
drolysis of the amide with concentrated hydrochloric acid; it boils
at 145° to 146° (13 mm.), sp. gr. = 0.9816 at 15°, [a], =+ 4.3°
at 15.5° (10 em. tube). It forms silver and ammonium salts, of
which the latter may be reconverted into the amide.

Oxydihydrofencholenonitrile, C,H,,O-CN, is produced in a yield
of about thirty-five per cent. by the action of air on fenchimine.
It is non-volatile with steam, boils at 153° to 154° (23 mm.) and
is insoluble in water. Sp. gr. is 0.9792 at 15°, np = 1.46464.at
18°, M= 47.11, and [a], = — 8° at 18° (10 cm. tube).

Oxydihydrofencholenamide, C,H,,O-CONH,, is obtained by hy-
drolysis of the oxy-nitrile with thirty per cent. alcoholic potash ;
it is recrystallized from ethyl acetate and melts at 78°. It is
readily soluble in boiling water, ethyl and methyl alcohol and
boiling ether, sparingly in cold water.

168 THE TERPENES.

Dihydrofencholenic acid lactam, C,,H,,ON, is formed, together
with an oil which has not yet been investigated, by gently warm-
ing a solution of oxydihydrofencholenamide in dilute hydrochloric
acid. It separates from the filtered solution on cooling in bril-
liant crystals, which melt at 136° to 137°; it is soluble in hot
alcohol and may be recrystallized from this solvent. It is not
attacked by permanganate ; when heated above its melting point,
it distills without decomposition. It is identical with Wallach’s
f-isofenchonoxime (m. p. 137°), which is prepared by dissolving
a-fencholenamide (m. p. 113° to 114°) in hot, dilute sulphuric acid
and precipitating the filtered solution with alkali.

0-Oxydihydrofencholenic acid, C,H,,O - COOH, is obtained, to-
gether with the oxy-amide, by the hydrolysis of the oxy-nitrile
with alcoholic potash; a small quantity of the lactone of this
acid is also formed at the same time. This acid crystallizes from
hot water or ethyl acetate in splendid, hard crystals, which melt
at 113° to 114°. It is a monobasic acid,.is soluble in boiling
water, readily soluble in alcohol, ether and ethyl acetate, spar-
ingly soluble in ligroine ; it forms silver and copper salts.

0-Oxydihydrofencholenic acid lactone, C,,H,,O,, is readily pro-
duced by warming the oxy-acid with dilute sulphuric acid ; it
separates from ethyl acetate in splendid, well formed crystals,
which melt at 72° and boil at 130° to 150° (10 mm.). It is
very volatile with steam, somewhat soluble in boiling water and
insoluble in sodium carbonate. It is dissolved by long continued
boiling with caustic alkalis.

Fenchocarboxylic Acids,’ C,,H,,(OH) - COOH.

When carbon dioxide is passed through a solution of fenclione
in ether to which sodium has been added, a mixture of different
compounds is obtained ; in order to separate them, the crude prod-
uct is distilled under 15 mm. pressure. The fraction boiling at
150° to 180° solidifies in the receiver, and consists of the two
isomeric fenchocarboxylic acids, carbofenchonone, C,,H,,O,, an-
hydrofenchocarboxylice acid, C,,H,,O,, and a pinacone, C,,H,,O,,
or a difenchone, C,,H,,O,. This mixture is treated with sodium
hydroxide or ammonia, shaken with ether, and the aqueous
liquor is acidified; a-fenchocarboxylic acid crystallizes from

this liquid more rapidly than the f-acid. The f-acid is also

more soluble in petroleum ether than the a-acid, and a final
separation may be made by means of this solvent.

1Wallach, Ann. Chem., 284, 324; 300, 294; Chem. Centr., 1899 (I1.),
1052; Nach. k. Ges. Wiss., Gittingen, 1899, No. 2; Ann. Chem., 315, 273.

——

neni a oe

CARBOFENCHONONE. 169

a-Fenchocarboxylic acid, C,,H,,O,, crystallizes from acetic acid,
melts at 141° to 142°, and boils without decomposition at 175°
at 11 mm. pressure. It is optically active, having a specific
rotatory power, [a], = + 11.28°, in a 4.5 per cent. ethereal solu-
tion ; by mixing equal weights of the active acids prepared from
d- and |-fenchone, an inactive acid is obtained, which melts at 91°
to 92°. It forms lead and silver salts.

f-Fenchocarboxylic acid, C,,H,,O,, melts at 76° to 77°, is
dextrorotatory, and is less stable than the a-acid; it forms fen-
chyl alcohol and anhydrofenchocarboxylic acid by heating at
ordinary pressure, and it is partially converted into the a-acid
by distillation in vacuum. It is changed into fenchone by the
action of sodium hypobromite or by an acid solution of perman-
ganate. It forms /ead and silver salts similar to those of the a-
acid. This acid is also formed by warming carbofenchonone with
an excess of a dilute solution of sodium hydroxide on the water-bath.

Wallach regards a- and $-fenchocarboxylic acids as trans- and
cis-modifications.

Anhydrofenchocarboxylic acid, C,,H,,O,, is prepared by boiling
a-fenchocarboxylic acid at atmospheric pressure, or by fusing the
a-acid with potash. It crystallizes from dilute acetone, melts at
175° and boils at 275° to 277° under ordinary pressure ; it is
difficultly soluble in water, is volatile with steam, and forms a lead
salt.
Carbofenchonone,’ C,,H,,O,, results by the distillation of lead
a-fenchocarboxylate in vacuum ; it separates from petroleum ether
in yellow crystals, has a slight odor resembling that of camphor,
melts at 96°, and boils at 273° to 274° under atmospheric pres-
sure. It dissolves in warm caustic soda, being converted into
B-fenchocarboxylic acid. It yields a monowime, C,,H,,O.NOH,
which crystallizes from methyl! alcohol in needles, melting at 108°;
and a dioxime, C,,H,,(NOH),, which is soluble in water, and melts
at 198° to 199°. By the action of ammonia it forms a compound,
C,,H,,NO, which crystallizes from alcohol and melts at 205°.

Carbofenchonone is an ortho-diketone.' By the action of zine
dust and acetic acid it is converted into an alcohol, C,,H,,O,, which
erystallizes from dilute alcohol and melts at 89°. When the
diketone is oxidized, it yields a dicarborylic acid, C,,H,,O,, which
melts at 172° to 173°.

A lactone, C,,H,,O,, is produced by the oxidation of a-fencho-
carboxylic acid with potassium permanganate ; it crystallizes from
dilute methyl alcohol, melts at 64.5°, and boils at 150° under 14
mm. pressure.

Wallach, Ann. Chem., 315, 273.

170 THE TERPENES.

A pinacone,' C,,H,,0,, or a difenchone, C,,H,,O,, is the neutral
crystalline compound formed as a by-product during the prepara-
tion of the fenchocarboxylic acids from fenchone; it melts at
122°. It yields no well defined derivatives, and decomposes,
when heated under reduced pressure at temperatures below 100°,
into fenchone and a non-crystalline product.

As a result of his extended investigations on fenchone and its
derivatives, Wallach suggests the following formula as the most
probable representation of the constitution of fenchone :

CH. ——-CUH
| H,C—C—CH;,
CH, CH.

Fenchone.

‘H—CH,

CO

10. FENCHYL ALCOHOL, C,,H,,OH.

Fenchyl alcohol is formed by the reduction of fenchone in an
alcoholic solution with sodium (Wallach ”).

Thirty grams of fenchone are dissolved in 135 to 140 grams of
alcohol in a capacious flask, and eighteen grams of sodium are
gradually added. When the evolution of hydrogen slackens, the
flask is warmed on a water-bath, and the solution of the last par-
ticles of sodium may eventually be accelerated by the cautious
addition of a small quantity of water. When all of the sodium is
consumed, enough water is added to dissolve the sodium alco-
holate which tends to separate; two layers are thus formed, the
one an aqueous solution of sodium hydroxide, the other a lighter,
alcoholic solution which contains fenchyl alcohol. The sodium
hydroxide solution is removed, and the fenchyl alcohol separated
by shaking the alcoholic solution with water ; at first it forms an
oil, which solidifies when agitated with ice-water. It is then
pressed on a porous plate, fused, dried with potassium hydroxide,
and rectified.

Larger quantities of fenchyl alcohol may also be prepared in
one operation by this method.

According to Bouchardat and Tardy,’ the benzoyl] esters of fen-
chyl alcohol and isoborneol are formed by heating the dextroro-
tatory terpene (pinene *), obtained from eucalyptus oil of Hucalyptus

1Wallach, Ann. Chem., 315, 273.

2Wallach, Ann. Chem., 2638, 143; see also Gardner and Cockburn, Journ.
Chem. Soc., 73, 276.

3Bouchardat and Tardy, Compt. rend., 120, 1417.

sCompare with Wallach and Gildemeister, Ann. Chem., 246, 283.

FENCHYL FORMATE. 171

globulus, with benzoic acid. By the action of certain acids (sul-
phuric, benzoic) on French (levorotatory) turpentine, Bouchardat
and Lafont’ obtained a mixture of dextrorotatory and inactive
fenchy] alcohols, which they at first designated as “ isocamphenol”
and “ synthetical isoborneol”’ ; on oxidation these two alcohols yield
levorotatory and inactive fenchone, respectively.

Fenchyl alcohol forms a colorless, crystalline mass, having a
penetrating and extremely disagreeable odor ; it is readily volatile
with steam, and is freely soluble in alcohol, ether, petroleum
ether, and ethyl acetate, but is insoluble in water.. It has the
specific gravity 0.933 at 50°, boils at 201°, and, as usually pre-
pared, melts at 40° to 42° ; pure fenchyl alcohol, however, formed
as a by-product in the preparation of the fenchocarboxylic acids”
or obtained by the hydrolysis of fenchyl hydrogen phthalate,*
melts at 45°.

Fenchyl alcohol prepared from dextrorotatory fenchone is
levorotatory ;* its specific rotatory power is [a@],= — 10.35°
(Wallach), and Ia] p = —13.37° (Gardner and Cockburn’). By
reduction, levo-fenchone yields dextro-fenchyl alcohol,’ whose
specific rotatory power is [a|,= + 10.36°. Inactive fenchy]l
alcohol results by mixing the two active modifications, and melts
at 33° to 35° (Wallach).

Wallach’ designates the levo-fenchyl alcohol obtained from
dextro-fenchone as D-l-fenchyl alcohol, and the dextro-alcohol
derived from levo-fenchone as L-d-fenchy] alcohol.

By heating the optically active modifications with three times
their amount of concentrated nitric acid, a fenchone is obtained,
which, respecting the direction and power of rotation, is identical
with that from which the fenchyl alcohol was prepared.

Fenchene, C,,H,,, is formed by warming fenchyl alcohol with
acid potassium sulphate, while tetrahydrofenchene, C,,H,,, is pro-
duced by reducing it with hydriodic acid and phosphorus.

The following derivatives of fenchyl alcohol have been pre-
pared by Bertram and Helle.*

Fenchyl formate, C,,H,,O-COH, boils at 115° under 40 mm.
pressure, and at 84° to 85° under 13 mm. pressure; it has a

1Bouchardat and Lafont, Compt. rend., 113, 905; 125, 111; 126, 755.
2Wallach, Ann. Chem., 284, 331.

3Bertram and Helle, Journ. pr. Chem., 16, 1900 (II.), 293.

4See Kondakoff and Lutschinin, Journ. pr. Chem., 62 (II.), 1.
5Gardner and Cockburn, Journ. Chem. Soc., 73, 276.

6Wallach, Ann. Chem., 272, 106.

TWallach, Ann. Chem., 302, 371.

172 THE TERPENES.

specific gravity 0.988 at 15°, and the optical rotation, [a] p= —
73° 14’.

Fenchyl acetate, C,,H,,O-COCH., boils at 87° to 88° under
10 mm. pressure, has a specific gravity 0.9748 at 15°, and a
specific rotation [a], = — 58.08°. Bouchardat and Lafont’ ob-
tained an acetic acid ester of their dextro-fenchyl alcohol, pre-
pared by the action of acids on French turpentine oil, which
boils at 125° to 127° (5 mm.), is strongly dextrorotatory, and
has the specific gravity 0.9817 at 0°.

Fenchyl benzoate,' C,,H,,O-COC,H,, boils at 183° to 188°
under 2 mm. pressure, and has the specific gravity 1.129 at 0°.
The alcohol regenerated from it has a lower optical rotation than
the original fenchyl alcohol.

Fenchyl phenylurethane, / NCH,

crystallizes in needles or tablets, and melts at 82° to 82.5°.

Fenchyl hydrogen phthalate, C,,H,,O,, crystallizes from alco-
hol, and melts at 145° to 145.5°. By hydrolysis it is readily
converted into pure fenchyl alcohol (m. p. 45°), hence this com-
pound is well adapted for the purification of fenchy] alcohol.

Fenchyl chloride, C,,H,,Cl, may be readily prepared by the fol-

lowing method (Wallach *). .
’ Forty-five grams of fenchyl alcohol are dissolved in eighty
grams of dry light petroleum or chloroform, and treated slowly
with sixty grams of phosphorus pentachloride. An energetic re-
action takes place, after which the liquid is poured off from small
quantities of unchanged .phosphorus pentachloride, and the petro-
leum ether and phosphorus oxychloride are removed as com-
pletely as possible by distillation in vacuum. The residue con-
taining fenchyl chloride is distilled in a current of steam, the
volatile oil dried over calcium chloride, and fractionated in vacuum.
Most of the substance boils at 84° to 86° under a pressure of 14
mm.

The product thus obtained has a specific gravity of 0.983 at
21°, and contains considerable quantities of non-chlorinated prod-
ucts as impurities. The phosphoric acid ester of fenchyl alcohol
is formed during the preparation of the chloride, and remains in
the residue from the steam distillation.*

1Bouchardat and Lafont, Compt. rend., 126, 755.

2Wallach, Ann. Chem., 269, 148; see also Gardner and Cockburn, Journ.
Chem. Soc., 73, 276; Kondakoff and Lutschinin, Journ. pr. Chem., 62

4H yee
3Wallach, Ann. Chem., 284, 331.

FENCHYL IODIDE. 173

According to more recent investigations by Wallach,! fenchyl
chloride, prepared as above described, is not an individual sub-
stance. The optical rotation of the chloride, obtained from D-l-
fenchyl alcohol, varies between the limits [a], = — 18° and +
5.1°, in a one decimeter tube ; the direct product of the action of
phosphorus pentachloride on the alcohol is always levorotatory,
but subsequent treatment, as repeated distillations, modifies the
rotatory power to a degree which has not yet been accurately
determined. It is probable, therefore, that D-l-fenchyl alcohol
gives D-l-fenchyl chloride and D-d-fenchyl chloride; for when
pure D-l-fenchyl alcohol, phosphorus pentachloride and light
petroleum are mixed together at low temperatures, a strongly levo-
rotatory chloride is formed ; but when the reagents are mixed
without cooling and the reaction is completed on the water-bath,
a dextrorotatory fenchyl chloride may be obtained.

According to Kondakoff,? the action of phosphorus penta-
chloride on fenchyl alcohol gives an impure chloride containing
fenchene ; the crude chloride appears to be a mixture of a solid
secondary chloride with a much larger amount of liquid tertiary
chloride, which is much more easily decomposed by alcoholic
potash than the secondary chloride. Thus, by the action of alco-
holic potash on the crude fenchyl chloride at 100°, there is
produced, together with fenchene, a secondary fenchyl chloride,
C,,H,,Cl, which crystallizes from alcohol, melts at 79° to 80°, and
has the specific rotatory power [a], = + 16° 33’; it does not
react with moist silver oxide, and resembles bornyl chloride in
odor and other properties; fenchene is the only product at
150°.

A much purer fenchy] chloride? is obtained by heating fenchyl
alcohol on the water-bath with concentrated hydrochloric acid ; at
higher temperatures a dichloride is formed.

Fenchyl bromide, C,,H,,Br, is produced by the action of cold
hydrobromic acid on D-l-fenchyl alcohol ; it boils at 92° to 96°
(11 mm.), has the sp. gr. 1.2368 at 19.5°, np>= 1.4988 and Lal
= — 43°17’. A small quantity of a dibromide is also formed ;
it crystallizes from alcohol and melts at 49°. Fenchene is pro-
duced by the action of alcoholic potash on fenchyl bromide
(Kondakoff and Lutschinin).

Fenchyl iodide,* C,,H,,I, is prepared by the action of a solution
of hydrogen iodide saturated at — 20° on fenchy] alcohol at the
ordinary temperature ; it boils at 120° to 123° under 23 mm.

1Wallach, Ann. Chem., 302, 371; $15, 273.

Kondakoff and Lutschinin, Journ. pr. Chem., 1900 [II.], 62, 1.
3Kondakoff and Lutschinin, Chem. Zeit., 25, 131.

174 THE TERPENES.

pressure, hasa sp. gr. 1.4199 at 21°/4°, and a slight levorotation.
On treatment with alcoholic potash, it yields a fenchene boiling at
148° to 158°.

11. ISOFENCHYL ALCOHOL, C,,H,,OH.

As a result of experiments’ conducted in the laboratories
of Schimmel & Co., Leipzig, it has been found that an alcohol,
isomeric with fenchyl alcohol, is obtained by treating fen-
chene, C,,H,,, with a mixture of acetic and sulphuric acids
in the same manner as in the preparation of isoborneol* from
camphene. ‘This alcohol is called isofenchyl alcohol, and while
its method of preparation is analogous to that of isoborneol,
its chemical behavior is quite different from the latter com-
pound. Thus camphor may be converted into borneol, and
the latter, by means of camphene, into isoborneol; when this
substance is oxidized, camphor is again obtained. On the
other hand, fenchone is reduced to fenchyl alcohol, and this
compound may be converted into isofenchyl alcohol by first
preparing fenchyl chloride and fenchene; here the similarity
ceases, for, when isofenchyl alcohol is oxidized it is not con-
verted into fenchone, but yields an isomeric ketone, C,,H,,O.
When this ketone is reduced, it gives rise to a new alcohol,
C,,H,,OH, which apparently is not identical with fenchyl or
isofenchy] alcohol.

Isofenchyl alcohol is prepared* by heating fenchene with
glacial acetic acid and sulphuric acid, according to, Bertram and
Walbaum’s method of preparing isoborneol. It crystallizes in
colorless needles, melts at 61.5° to 62°, and boils at 97° to 98°
under a pressure of 13 mm.; it has a specific gravity 0.9613 at
15°, a refractive index, np = 1.48005, at the same temperature,
and a specific rotation, [a], = — 25.73°, in an alcoholic solution.
It reacts like a saturated secondary alcohol.

When a benzene solution of isofenchyl alcohol is boiled with
zine chloride, it loses water and yields a hydrocarbon, C,,H,,,
which is probably identical with fenchene.

Isofenchyl acetate, C,,H,,O.COCH,, boils at 98° to 99° under
14 mm. pressure, and has a specific gravity 0.974 at 15°. The
acetate, formed directly from fenchene by the action of glacial

1Schimmel & Co., Semi-Annual Report for Oct., 1898, 49; April, 1900, 55
and 60; Bertram and Helle, Journ. pr. Chem., 61, 1900 (II.), 293.

?Bertram and Walbaum, Journ. pr. Chem., 49 (II.), 1.

3According to Wallach, Ann. Chem., 315, 273, it is also formed from
fenchene alcoholate, C,H,,OC,H;.

—— a ee

ISOFENCHYL HYDROGEN PHTHALATE. 175

acetic acid, boils at 89° to 90° at 8 mm. pressure, and at 15° it
has the specific gravity 0.9724.
Isofenchyl phenylurethane,

NHC,H
% a
N\OC,Hy,

crystallizes from alcohol, and melts at 106° to 107°.

Isofenchyl hydrogen phthalate, C,.H,,O,, is a colorless, crystalline
powder, and melts at 149° to 150°. It is converted into pure
isofenchy] alcohol on hydrolysis, hence it may be employed for the
purification of the alcohol.

The ketone, C,,H,,O, is produced by the oxidation of isofenchyl
alcohol with chromic acid ; it is isomeric, but not identical, with
fenchone. It boils at 193° to 194°, has the specific gravity
0.950, and the refractive index, n, = 1.46189, at 15°. Its oxime
melts at 82°.

The alcohol, C,,H,,OH, is formed by the reduction of the pre-
ceding ketone with alcohol and sodium. It boils at 83° to 84°
under 8 mm. pressure, and forms a hydrogen phthalate melting at
240° to 111°.

Some of the characteristic differences between isofenchyl alcohol
and its derivatives, and fenchyl alcohol and its compounds are
more readily observed from the following table.’ It will be noted
that the compounds derived from isofenchyl alcohol have, in most
instances, higher boiling and melting points, than the correspond-
ing fenchy]l alcohol derivatives.

Isofenchy] alcohol. Fenchy] alcohol.
Melting point, 6E.5° to 62°, —- 45°.
Boiling point, 97° to 98° (13 mm.), 91° to 92° (11 mm.).
Phenylurethane, m. p. 106° to 107°, m. p. 82° to 82.5°.
Acety! ester, . liquid, b. p. 98° to 99° _| liquid, b. p. 88° (10
(14 mm. ), mm. ).
Hydrogen phthalate, m. p. 149° to 150°, m. p. 145° to 145.5°.
Hydrocarbon resulting by| Fenchene (?) b. p. 155° | Fenchene b. p. 154° to
dehydration of alcohol, | to 156°, 156°.
Compound formed by Ketone, ©, ,H,,0, liquid, | Fenchone, C,)H,,0, m. P-
oxidation of alcohol, b. p. 193° to 194°, + 6°; b. p. 191° to 192°.
Oxime of preceding com- | m. p. 82°, m. p. 164° to 165°.
pound,

1Schimmel & Co., Semi-Annual Report, April, 1900, 56.

176 THE TERPENES.

12, FENCHOLENYL ALCOHOL AND ISOFENCHOLENYL
ALCOHOL, C,,H,,OH.

Fencholeny! alcohol is the alcohol corresponding to a-fencho-
lenamine, a reduction product of a-fencholenonitrile, C,H,,CN.
The following process is well adapted for its preparation (Wallach
and Jenkel’).

Fifty grams of a-fencholenamine nitrate are dissolved in 100
cc. of water, and treated with a solution of sixteen grams of sodium
nitrite in thirty ec. of water. A vigorous evolution of gas takes
place when this mixture is heated in a flask, fitted with a reflux con-
denser, and a dark colored oil results. The product is submitted
to steam distillation, and the distillate, which contains a mixture of
fencholenyl alcohol and unchanged a-fencholenamine, is treated
with a solution of oxalic acid ; this is again distilled in a current
of steam. A small quantity of a hydrocarbon is formed, together
with the alcohol.

Fencholenyl alcohol boils at 94° to 96° under a pressure of
17 mm., has a specific gravity 0.898 and a refractive power,
np = 1. 4739, at 20°; it has an agreeable odor, very similar to
that of terpineol. It is not converted into fenchenole, C,,H,,0,
by treatment with hot, dilute sulphuric acid. Its acetic acid solu-
tion is colored a deep violet on the addition of hydrochloric acid.
A detailed investigation of the chemical behavior of this alcohol
has not yet been made.

Isofencholenyl alcohol, C,,H,,OH, is apparently not identical
with the preceding compound (Wallach*). When a-isofenchonox-
ime (a-fencholenamide) is reduced with sodium and alcohol, a-
fencholenic acid, a-fencholenamine and isofencholenyl alcohol
are formed ; the reaction-product is then distilled with steam, iso-
fencholenyl ‘alcohol and a-fencholenamine being obtained in the dis-
tillate. These two compounds are extracted with ether, and the
amine is removed from the ethereal solution by precipitation with
hydrochloric acid gas. The alcohol is redistilled with steam and
rectified (Wallach *).

It is an unsaturated compound, boils at 218°, and has the spe-
cific gravity 0.927 and the index of refraction, np = 1.476, at
20°; M= 47.04, while the calculated value for its molecular
refraction is M= 47.15. Its solution in glacial acetic acid is
colored deep red on the addition of concentrated sulphuric acid.

1Wallach and Jenkel, Ann. Chem.,. 269, 375; Wallach, Ann. Chem., 300,
294.

2Wallach, Ann. Chem., 300, 294.

3Wallach, Ann. Chem., 284, 336.

\ 9 as 2

FENCHENOLE. , 177

13, FENCHENOLE, C,,H,,O.

Fenchenole is produced when isofencholenyl alcohol is heated
with dilute sulphuric acid (one volume of concentrated acid and
seven volumes of water) in a reflux apparatus, for six to eight

hours ; the sulphuric acid solution at first assumes a beautiful rose
— eolor, but soon becomes colorless. The last traces of the unsat-
urated isofencholenyl alcohol are removed by agitation with per-
manganate, and pure fenchenole is obtained by distilling the
product in a current of steam (Wallach ’).

Fenchenole is isomeric with cineole, which it closely re-
sembles, and is a saturated compound. It boils at 183° to 184°,
has the specific gravity 0.925 and the refractive power, np =
1.46108, at 20°. It does not react with hydroxylamine, and is
similar to cineole in its odor and behavior. ‘Thus, an additive
product is formed by passing a current of dry hydrobromic acid
gas into a solution of fenchenole in petroleum ether ; it separates
in white crystals, which are decomposed by moisture into a dark
colored liquid.

The formation of fenchenole from isofencholenyl alcohol re-
sembles the conversion of the alcohols methyl hexylene carbinol
and methyl heptylene carbinol into saturated oxides (Wallach ’).

1 Wallach, Ann. Chem., 284, 336.
_2Wallach, Ann. Chem., 275, 170 and 172.

II. COMPOUNDS WHICH MAY BE REGARDED AS
DERIVATIVES OF THE HYDROCYMENES.

A. SUBSTANCES CONTAINING TWO ETHYLENE LINK-
AGES. KETONES, C,H,,0, AND ALCOHOLS, C,,H,,0H.

1. CARVONE, C,,H,,0.

Carvone (formerly called carvol) occurs in nature in two modi-
fications distinguished by their optical behavior. It has long been
known that dextrorotatory carvone is the characteristic constitu-
ent of the fractions boiling above 200° of the oil of caraway
(Carum carvi), and of the oil of dill (Olewm anethi). On the other
hand, levorotatory carvone is found in the oil of spearmint,
and in kuromoji oil.’

When equal quantities of dextro- and levo-carvone, or their
optically active derivatives, are mixed, optically inactive com-
pounds are obtained, which stand in the same relation to their
active components as racemic acid does to the optically active tar-
taric acids, or dipentene to dextro- and levo-limonene. Carvone
may be considered as limonene in which two atoms of hydrogen
of a methylene group are replaced by an oxygen atom; in fact,
transformations of limonene and dipentene into carvone have
been observed. The first of these consists in the formation of
carvoxime from limonene and dipentene nitrosochlorides, and car-
vone is obtained by boiling carvoxime with dilute sulphuric acid.
A second transformation must be considered more in detail.

According to Wallach,® if limonene tetrabromide, C,,H,,Br,,
be treated with methyl alcoholic potash, two molecules of hydro-
bromic acid are eliminated, and another atom of bromine is re-
placed by a methoxyl-group ; the resultant compound, C,,H,,Br-
OCH,, may be reduced to carveol methyl ether, and when this
optically active substance is dissolved in acetic acid and oxidized
with chromic acid, inactive carvone is obtained.

On the other hand, a conversion‘ of carvone into limonene
may be accomplished as follows. On reduction with alcohol and

1Fliickiger, Ber., 9, 468.

2Kwasnick, Ber., 24, 81.

3Wallach, Ann, Chem., 281, 127; compare Ann. Chem., 264, 12.

4L. Tschigaeff, Ber., 33, 735.
178

CARVONE HYDROGEN SULPHIDE. 179

sodium, d-carvone yields dihydrocarveol, which is then con-
verted into methyl dihydrocarvyl xanthate, C,,H,,O-CS,CH, ;
this compound, on distillation, forms two hydrocarbons, one of
which yields limonene tetrabromide when it is treated with bro-
mine. By the action of zinc dust on the alcoholic solution of the
tetrabromide, pure dextro-limonene is obtained.

Another interesting transformation which should be mentioned
here is the conversion of terpineol into carvone.' When terpineol
nitrosochloride is heated with an alcoholic solution of sodium ethy-
late, oxydihydrocarvoxime, C,,H,,(OH)NOH, is formed, and dilute
‘sulphuric acid converts this compound into inactive carvone.

Pinole may also be converted into carvone by oxidizing pinole
hydrate with a glacial acetic acid solution of chromic acid, when
oxydihydrocarvone,” C,,H,,O(OH), is obtained ; the latter yields
an oxime, which is converted into inactive carvone by warming
with dilute sulphuric acid.

Pinole tribromide,* C,,H,,OBr,, and isopinole dibromide,*
C,,H,,O-Br,, also yield inactive carvone by gently boiling with a
ten per cent. aqueous solution of potassium hydroxide.

Dextrorotatory carvone may be obtained in quite a pure condi-
tion by repeated fractional distillations of the oil of caraway.
In the preparation of levo-carvone, however, it is essential to pre-
pare the hydrogen sulphide derivative, and to decompose it with
alcoholic potash, and to distill the resulting carvone with steam.*

PROPERTIES.—Pure carvone, regenerated from the hydrogen
sulphide compound, boils at 223.5°, and has the specific gravity
0.9598 at 0°.°

When carvone is treated with certain reagents, as potassium
hydroxide or better with glacial phosphoric acid, it is converted
into the isomeric compound, carvacrol; in this transformation,
however, it is most advantageous to first convert carvone into its
hydrochloride, and to treat this with anhydrous zinc chloride
(Reychler). According to Klages,’ carvacrol is produced quanti-
tatively by heating carvone with formic acid in a reflux apparatus.

Carvone hydrogen sulphide,

OH
CH,
SH

1 Wallach, Ber., 28, 1773; Ann. Chem., 291, 342. s
2Wallach, Ann. Chem., 291, 342.
’Wallach, Ann. Chem., 306, 273. io
*Macheleidt, Inaug. Diss: . Géttingen, 1890; Wallace

224.
5A, Beyer, Ber., 16, 1387; Schreiner, Pharm. Re”
6A, Klages, Ber., 32, 1516.

180 THE TERPENES.

is produced by passing hydrogen sulphide into the strongly am-
moniacal alcoholic solutions of the fractions of the above-men-
. tioned ethereal oils which contain carvone. The compound is
purified by reerystallization from a mixture’ of chloroform and
alcohol, or better from glacial acetic acid; it separates from the
latter solvent in long needles,” and melts at 187°. The melting
point 210° has also been frequently reported for this com-
pound.*

Hydrochlorocarvone, C,,H,,O. HCl, was first prepared by Varren-
trap. Goldschmidt and Kisser* obtained it by saturating carvone
with dry hydrochloric acid gas. It is an oily liquid, and decom-
poses on distillation; it corresponds to hydrochlorolimonene.
When treated with hydroxylamine, it yields hydrochlorocarvoxime,
which is isomeric with limonene nitrosochloride. The phenyl-
hydrazone of hydrochlorocarvone melts at 137°.

It is worthy of note that it is most convenient to employ
hydrochlorocarvone to effect the well known transformation of
carvone into its isomeride, carvacrol. To this end, hydrochloro-
carvone is heated with not more than two per cent. of its weight
of anhydrous zine chloride, and, in order to modify the violent
reaction, thirty-three parts of glacial acetic acid are added. At
95° hydrogen chloride is given off, and the reaction is complete
at 110° to 120° in twenty minutes. The resulting carvacrol is.
washed with water, and rectified. The yield amounts to ninety
per cent. of the theoretical (Reychler ’).

Hydrobromocarvone, C,,H,,O-HBr, was obtained by Gold-
schmidt and Kisser® as a thick oily compound by treating carvone
with hydrogen bromide. According to Baeyer,’ it is prepared
by gradually adding carvone to a solution of three molecules of
hydrogen bromide in glacial acetic acid, in the cold; after stand-
ing for fifteen minutes the liquid is poured onto ice, and the oil
which separates is washed with water, extracted with ether, and
the ethereal solution agitated with sodium carbonate. The solution
is then dried with fused sodium sulphate, and allowed to remain in
a vaci.uin desiccator, when hydrobromocarvone is deposited in
crystalline masses ; these are pressed on a porous plate at a low

‘A. Beyer, Arch. Pharm., 221, 283.
vheleidt, Inaug. Diss. Gittingen, 1890.
arel & Co., Semi-Annual Report, April, 1898, 47; see also Claus -
Journ. pr. Chem., 39, 365.
. and Kisser, Ber., 20, 488.
‘oe. Chim., [3], 7, 31; Ber., 25, 208; Ref. German patent,

“<. Ber., 20, 2071.

HYDROBROMOCARVONE DIBROMIDE. 181

temperature, and washed with methyl alcohol. It is crystallized
from ether, and melts at 32°.

Hydrobromocarvoxime is produced by the action of hydroxyl-
amine on hydrobromocarvone, and melts at 136°. When hydro-
bromocarvone is treated with phenylhydrazine, a phenylhydrazone,
melting at 123° to 125°, is formed.

According to Baeyer, alcoholic potash withdraws the elements
of hydrogen bromide from hydrobromocarvone, and converts it
into eucarvone, a ketone isomeric with carvone.

According to Harries,’ when hydrobromocarvone is dissolved
in methyl alcohol and is reduced with zine dust, about one-quarter
of the product is carvone, while the remainder consists of a ketone,
4°-menthene-2-one, C,,H,,O, which is isomeric with dihydro-
carvone.

Hydrobromocarvone dibromide, C,,H,,O-HBr.Br,, is formed
when bromine (one molecule) is added to a solution of carvone in
glacial acetic acid containing hydrobromic acid. The compound
obtained from optically active carvone is an oil, while that derived
from inactive carvone is a solid. The latter is prepared by dis-
solving thirty grams of inactive carvone in sixty cc. of a cold, con-
centrated solution of hydrobromic acid in glacial acetic acid, and
treating the well cooled solution with thirty cc. of a solution of
-one volume of bromine in two volumes of glacial acetic acid.
The tribromide thus formed is precipitated with water, and crystal-
lized from moderately warm ethy] acetate ; it separates in splen-
did, well defined, monoclinic crystals, which melt at 74° to 76°
(Wallach’).

When an amy! alcoholic solution of the liquid active, or crys-
talline inactive, tribromide is saturated with dry ammonia, am-
monium bromide and a keto-amine,*? C,,H,,O -NH,, are formed :

C,)H,,OBr s Br, a 4NH, = 3NH,Br a. C,)»H,,0NH,

This keto-amine is a liquid, but yields a solid hydrochloric acid salt.

When the keto-amine is treated with hydroxylamine, it is con-
verted into an oxy-owime, C,,H,,(OH)NOH ; it crystallizes from
methyl alcohol or hot water in needles ; the oxy-oxime resulting
from the active tribromide melts at 100°, and that prepared from
the inactive modification melts at 105°. :

When the hydrochloride of the keto-amine, C,,H,,ONH, - HCl,
is submitted to dry distillation, hydrogen chloride is eliminated
and a solid amine, C,,H,,ON, results; this base ‘separates from

1Harries, Ber., 34, 1924.

2Wallach, Ann. Chem., 286, 119.
3Wallach, Ann. Chem., 286, 119; 305, 245.

182 THE TERPENES.

methyl alcohol in white crystals, melts at 165° to 167° (when
the active carvone tribromide was originally employed), and ap-
pears to be isomeric with the liquid keto-amine.

When the keto-amine hydrochloride is treated with an aqueous
solution of an alkali, the free base separates as an oil ; if the mix-
ture be allowed to stand for a considerable time, or if it be boiled
for a short time, the liquid base is converted into a solid lactone,
C,,H,,0, (carvenolide), ammonia being eliminated :

142
C,oH,;0NH, + H,O = NH; + ©, oH;,0;.

Carvenolides, C,,H,,O,.—D-1-Carvenolide is the lactone corre-
sponding with the keto-amine derived from dextro-carvone.
Thirty grams of d-carvone are dissolved in sixty cc. of a saturated
solution of hydrogen bromide in glacial acetic acid, and the well
cooled solution is treated slowly with ten ec. of bromine ; the
product is poured into ice-water, and the oily carvone tribromide
is separated and washed well with water. The oil is then dis-
solved in 200 cc. to 350 ce. of amyl alcohol, the solution is cooled
and saturated with ammonia; after standing for two hours, the
product is distilled with steam. A heavy oil is obtained, which
is separated, dried and distilled in vacuum; the fraction boiling
at 130° to 140° solidifies gradually when placed in a freezing
mixture, and after recrystallization from methyl alcohol it melts
at 41° to 42°. It is levorotatory, [a], = — 138.5°. It unites
with one molecule of bromine, forming a dibromide, C,,H,,O,:Br,,
which crystallizes from ethyl acetate, melts at 97° to 99°, and is
levorotatory, [a], = — 67.05°.

L-d-Carvenolide is prepared as above described from levo-carv-
one; it melts at 41° to 42°, and is dextrorotatory, [¢])= +
143.3°. Its dibromide melts at 97° to 99°, and is dextrorotatory.

Inactive carvenolide is prepared by crystallizing a mixture of
equal quantities of D-l- and L-d-carvenolide, or it may be
obtained directly from the crystalline, inactive carvone tribro-
mide; it melts at 71° to 72°. Its dibromide is inactive, melts at
95° to 96°, and is reconverted into i-carvenolide by treating with
zinc and glacial acetic acid.

Carvenolic acids, C,,H,,O,.—These acids are formed by heating
the carvenolides with a large excess of a solution of sodium meth-
ylate, for eight or nine hours, on the water-bath. D-d-Carvenolic -
acid is produced from D-l-carvenolide, which is obtained from
dextro-carvone ; it melts at 133°, and has the specific rotatory
power, [4], = + 178.7°. L-I-Carvenolic acid melts at 133°, and
is obtained from L-d-carvenolide ; inactive carvenolic acid melts
at 135° to 136°. These acids are unsaturated compounds, like

CARVONE DICHLORIDE, 183

the corresponding carvenolides, and in a glacial acetic acid solu-
tion they add bromine.

When D-d-carvenolic acid is fused with potash, it gives rise to
some volatile, liquid acids, together with a solid acid, C 7H O, 5 ; this
is volatile with steam, melts at 130° to 131°, and is levorota-
tory, [4]>= — 2.04°. It isan unsaturated compound, and adds
bromine, forming a dibromide, C,H,,O,Br,, which melts at 150°.

Carvenolic acid is oxidized by chromic acid or nitric acid, yield-
ing in each case the same monobasic acid, C,H,,O,, which melts
at 201° to 202°.

Carvone tetrabromide, C,,H,,O-Br,, is obtained by the careful
addition of 6.6 cc. of bromine to a cold solution of ten ce. of
dextro- or levo-carvone in ten ce. of glacial acetic acid ; towards
the end of the operation the liquid becomes cloudy, and very soon
solidifies. The crystals are filtered and washed with methyl
alcohol; the mother-liquors contain a liquid a-carvone tetra-
bromide. The crystalline f-tetrabromide is recrystallized from
acetone to which a small quantity of methyl alcohol is subse-
quently added; it separates in beautiful, brilliant, orthorhombic
crystals, and melts at 120° to 122°. The crystals are optically
active, and have hemihedral, enantiomorphous forms, which in
the case of those obtained from levorotatory carvone have the
hemihedral faces in the opposite position from those derived from
dextrorotatory carvone (Wallach’).

Inactive f-carvone tetrabromide is formed by mixing the solu-
tions of equal quantities of the dextro- and levorotatory modifica-
tions, or by the bromination of inactive carvone ; it separates in
monoclinic crystals and melts at 107° to 109°. Racemic a-
carvone tetrabromide is an oil.

a- or $-Carvone pentabromide, C,,H,,Br,O, is obtained by treat-
ing a- or f-carvone tetrabromide in glacial- -acetic acid or carbon
tetrachloride solution with bromine. The active modifications of
the a-pentabromide separate in monoclinic crystals and melt at
142° to 143°, and the inactive melts at 124° to126°. The active
f-pentabromide melts at 86° to 87°, while the racemic derivative
melts at 96° to 98°.

Hydrobromocarvone dibromide, carvone tetrabromide and the
corresponding pentabromides yield carvone when they are reduced
with zine dust and glacial acetic acid in the cold (Wallach*).

Carvone dichloride, C,,H,,Cl,, is formed by the action of phos-
phorus pentachloride on carvone ; it is an oil, having the specific

1Wallach, Ann. Chem., 286, 119.

2Wallach, Ann. Chem., 279, 390; 286, 120.
3Klages and Kraith, Ber., 32, 2550.

184 THE TERPENES.

gravity 1.188 at 18°, and is converted into 2-chlorocymene by
heating with quinoline, dilute sulphuric acid, or alcoholic potash.
2-Chlorocymene or 2-bromocymene may be obtained directly from
earvone by adding the latter to phosphorus pentachloride or pen-
tabromide covered with a layer of petroleum ether.

When carvone is reduced with aleohol and sodium, one double
linkage in the molecule becomes single by the addition of hydro-
gen, and an alcohol, dihydrocarveol,' C,,H,,OH, results :

C,)>H,,0 -- 4H = C,,)H,,OH.

In a similar manner, dihydrocarvylamine, C,,H,,NH,, corre-
sponding to dihydrocarveol, and not the base, C,,H,,NH,, is
formed by treating carvone with ammonium formate (Leuck-
hart).

Galdacheidt and Kisser’ obtained a hydrazone by the action of
phenylhydrazine on carvone; according to Baeyer,* it melts at
123° to 124°.

CARVOXIME AND ITS DERIVATIVES.

Carvoxime, C,,H,,. NOH, was first prepared by Goldschmidt’ by
the action of hydroxylamine on dextrorotatory carvone. Tilden °®
had previously obtained a compound, C,,H,,NOH (nitrosoterpene),
by treatment of limonene nitrosochloride with alcoholic potash.
Goldschmidt recognized the identity of Tilden’s product with car-

voxime, and thereby demonstrated for the first time the close rela--

tion of carvone to limonene. A more complete explanation of this
relation was then given by Wallach’s researches. The facts dis-
covered by Wallach’ are briefly presented in the following.

1. Carvoxime (m. p. 72°) obtained from dextro-limonene nitro-
sochloride is optically levorotatory, as Tilden had already ob-
served, and may also be prepared from levo-carvone and hydroxyl-
amine. On the other hand, levo-limonene nitrosochloride yields
a dextrorotatory carvoxime, which has the same melting point
(72°), and possesses a rotatory power of equal strength but of op-

1Wallach, Ann. Chem., 275, 110; compare Leuckart, Ber., 20, 114, and
Lampe, Inaug. Diss. Gittingen, 1889.

2Wallach, Ann. Chem., 275, 119; Leuckart and Bach, Ber., 20, 105;
Lampe, Inaug. Diss. Géttingen, 1889.

3Goldschmidt and Kisser, Ber., 20, 2071.

4Baeyer, Ber., 27, 811.

5Goldschmidt, Ber., 17, 1577.

6Tilden, Jahresb. Chem., 1877, 429.

TWallach, Ann. Chem., 245, 256 and 268; 246, 226; 270,171.

—_—

oT

2 Het

OPTICALLY ACTIVE CARVOXIME. 185

posite direction to that of the oxime obtained from dextro-limo-
nene nitrosochloride ; it is identical with the dextrorotatory car-
voxime obtained from the oil of caraway.

2. The carvoximes obtained from a- and f-limonene nitroso-
chlorides are identical.

3. Optically inactive carvoxime (m. p. 93°) is obtained by the
elimination of hydrochloric acid from a- and /-dipentene nitroso-
chlorides. It may also be prepared by the combination of equal
portions of levo- and dextro-carvoximes.

The above-mentioned modifications of carvoxime combine with
the halogen hydrides; the hydrochlorocarvoximes obtained in this
manner may also be prepared from the hydrochlorocarvones and
hydroxylamine. The carvoximes and hydrochlorocarvoximes also
form benzoyl esters, but it should be especially noted that the
benzoyl derivatives of hydrochlorocarvoximes are not identical
with the benzoyl derivatives of limonene or dipentene nitroso-
chlorides, and that the hydrochlorocarvoximes are not identical
with the limonene or dipentene nitrosochlorides.

If hydrogen chloride be removed from hydrochlorocarvoxime,
carvoxime is not regenerated, but isocarvoxime is formed. It
must be observed that isocarvoxime does not stand in any known
relation to eucarvone, which is produced by the splitting off of
hydrobromic acid from hydrobromocarvone.

The following tables (pp. 186, 187), may serve to illustrate
what has already been mentioned, together with that which fol-
lows in the more detailed description of carvoxime and its
derivatives.

Optically active carvoxime, C,,H,,.NOH, may be prepared by
the action of hydroxylamine on carvone (Goldschmidt), or by
treating limonene nitrosochloride with alcoholic potash (Tilden,
Goldschmidt and Wallach). Dextrorotatory carvoxime is most
readily obtained from carvone of oil of caraway, while levorota-
tory carvoxime is best prepared from dextro-limonene nitrosochlo-
ride, since this is more accessible than levo-carvone of the oil of
Mentha crispa.

Wallach * recommends the following method for the preparation
of dextro-carvoxime from the carvone obtained from caraway oil.

Fifty grams of carvone are dissolved in 250 cc. of alcohol and
treated, with frequent shaking, with a hot solution of fifty grams
of hydroxylamine hydrochloride in fifty grams of water ; a warm
solution of fifty grams of potassium hydroxide in forty cc. of water
is then added to the clear liquid. The solution assumes a yellow
color, and is then allowed to cool, without further heating ;

1Wallach, Ann. Chem., 275, 118; 277, 133.

THE TERPENES.

186

——<_o-

Saye

° ‘ " (poxy Apunry you st [(OFT)

(.06 *d ‘ur)

*HDOOONIO"H"'D OpHorqoosoayza ousuomny [Aozueq eaTouuy

ji

(pexy A[ury you st [OH)
(oOLT ©} .601 “4 ‘ur)
*H*OODONIO"H"D pHorqoosonjta eusuoury [éozu0q-04eT

\ K

(082 ‘d “ur)
HON"H"9 ‘ourxoarvo-0.1yx0q

‘d ‘ur) (ohOI % 801 “d ‘ur)
punodu0g-¢ punodm0p-»

(pexy ATorry jou 8! [OH) )
HONIO"H"D ‘opmoyyoosoazyru oueuOUNT]-OAe'T .

Ty" ‘ousuoUll[-OAerT

os

(poxy Aang you st 1H)

(OIE 0 0601 “4 “ut)
*°9000 ache ‘eplto[yoosoajru eueuOUITT aca a
| ]

(084 ‘d ‘ur)
HON" Hd ‘owrxoarnd-0ao'T

see

(.90T “d “ur) (oFOT % gor “d ‘ur)
punodwoy-¢ punodmop-»

(paxy ATuray you st (OH)
HONIO"H") ‘eplopyoosonru eusuourt]-01.x0q

yyy ‘auduoUTT]-O1;XOq

‘LI WOU ATAIUAQG SGNNOdWOD ANV AGIYOTHOOSOULIN ANANOWIT ‘[ AIAVY,

187

OPTICALLY ACTIVE CARVOXIME.

(pews Ayuar ray SI 10H)

‘ (ottt “d -ur)
TO0D0ON" HH") * IOH ‘ourproaceoozoproorpAy [fozueq satyovUT
pexy spay st [OH (Pex Ayu A gel st (0H)
es (air “d ‘on (oS1L
'H°OOOON"H™) : OH “eurxoarvoor0;yoorpsy ere oar) *H°0000N"H")D : OH parfroarsoosoqyoospLy [fozuaq-0aeT
GOT “a “ut
SH *DODON HD CourxoAavo [Aozuaq oAtjovuyt
Be a
(ZIT ‘d ‘u)

SPOOOON"H"'D fautxoaceoost [Aozueg

|

~—r 3 ane ‘d ‘m) (oatjorut) 3c6 d “ur)
TPOOOON™ H"D ‘ourrxoarvo | ozu0g-0AarT (zpr ‘d ‘ar) *HOOOON™ HD ‘ourxoareo [kozueq-013x0q
HON" H"D ne )
(pexy Apuury st (OH)
(.¢°ear “d ‘u)
HON HD fourrxoarvoo10;yoorp£y @atyo
Pix,
-
(pexy Apu4g st [OH) (paxy Xpunty’st 19H)
(o¢81|"d ‘ur) (o¢er ‘d ‘ar)
IOH: HON"H") ‘owtxyoarvoor0pyoorpAy-0aAeyT = JOH: HON‘H"( ‘oatrxoa.rvoo10;qoospéy-01}.xPq
(06 “d “u)
HON H%) ‘ourxoarvo QATPOVUT
aN.
” Re The
(34 *d ur) (2 “d “ur)
HON" Hd ‘eurxoArvo-0Ao'T HON" H"9 ses A1¥0-019X9(T
. o"H"D rad ime OM A"y ‘ouoarvo-017x0q

‘SHAILVAINS(T SLT GNV GWIXOAUVD ‘[] AIAVL

_——— in eee ’ Oe EE

188 THE TERPENES.

potassium chloride is thrown out, and the liquid is poured into
cold water. Most of the carvoxime separates at once in solid
flakes, and is collected on a cloth filter and pressed. It is re-
crystallized by dissolving 100 grams of the dry compound in 200
grams of hot alcohol, to which some ether is added directly before
filtering. The yield of carvoxime is large, but not quantitative.
Small quantities of a liquid compound are always formed, which,
together with some solid carvoxime, remain dissolved in the al-
coholic, alkaline solution. (For the method of determining the
carvone in ethereal oils as carvoxime, see Kremers, Journ. Soc.
Chem. Indus., 20, 16.)

Levorotatory carvoxime is obtained by adding fresh a- or
f-dextro-limonene nitrosochloride, in small portions at once, to a
solution of sodium in alcohol; the mixture is boiled for a few
minutes, and the resultant carvoxime precipitated by pouring the
reaction-produet into water. It is crystallized from a mixture of
alcohol and ether.

Dextro- and levo-carvoximes melt at 72°.

That carvoxime contains the isonitroso-group is proved by
numerous observations, which were made for the most part by
Goldschmidt. Thus, carvoxime reacts with acetyl and benzoyl
chloride ; it may also be converted into a methyl ether. Hydro-
chloric acid precipitates a hydrochloric acid salt from the ethereal
solution of the oxime. Carvoxime is soluble in acids and
alkalis.

By boiling with dilute sulphuric acid, carvoxime is decom-
posed into carvone and hydroxylamine.

Carvoxime is an unsaturated compound, and, like carvone, is
capable of combining with one molecule of a halogen hydride.

When the oxime is reduced with sodium and alcohol, dihydro-
carvylamine, C,,H,.NH,, is formed ; this is the same base that is
obtained by the treatment of carvone with ammonium formate by
Leuckart’s method (Wallach ”).

Just as carvone may be changed into carvacrol, so carvoxime
is convertible into aromatic amines. When ten grams of car-
voxime are added gradually to twenty grams of concentrated
sulphuric acid, the acid becomes dark colored and warm. Care
must be taken that the liquid does not become too hot. When
the reaction is complete, the product is diluted with water, and
a clear solution of amidothymol is obtained (Wallach*). The
formation of this amine is probably preceded by a conversion of

1Goldschmidt, Ber., 17, 1577 and 2072; 18, 1729.

2Wallach, Ann. Chem., 275, 119.
8Wallach, Ann. Chem., 279, 369.

OPTICALLY ACTIVE CARVOXIME. 189

earvoxime into cymylhydroxylamine, which is analogous to the
transformation of carvone into carvacrol :

Hi; {
H sini ne a OH
HG OH,
x
C3H, CH,
Carvone. Carvacrol. Carvoxime. Cymylhydroxylamine.

The investigations of Friedlinder’ and Gattermann? have
shown that the aromatic hydroxylamines are instantly converted
into the isomeric para-amido-phenols. In an analogous manner
cymylhydroxylamine must be converted into para-amidothymol :

A x
S

H °—NH - OF H NH,
| nm
H H HO H
Cymylhydroxylamine. Para-amidothymol.

The constitution of para-amidothymol (m. p. 166° to 167°)
is proved by its conversion into thymoquinone.

If, according to the recent conception of terpineol as a d'-
terpen-8-ol, we ascribe to carvone the formula,

fi

H,C ‘on,

then we must consider that the transformations into carvacrol
and p-amidothymol are accompanied by transpositions of the
double linkage.

1Friedlinder, Ber., 26, 177; 27, 192.
2Gattermann, Ber., 26, 1845 and 2812.

190 THE TERPENES.

Carvoxime undergoes a molecular change in another manner
when a mixture of twelve cc. of sulphuric acid, twenty cc. of
water and ten cc. of alcohol is added slowly, drop by drop, to a
- warm solution of ten grams of carvoxime in thirty cc. of alcohol,’
or when carvoxime is heated with concentrated aqueous potash at
230° to 240°. In both cases carvacrylamine, C,,H,,NH,, i
produced, probably by the reduction of the primarily formed
cymylhydroxylamine :

H;

’

HC -NH-OH = Ja
He H

Y al

Inactive carvoxime, C,,H,,-NOH, is obtained when dipentene
nitrosochloride is boiled with alcoholic potash, hence it was long
known by the name “ nitrosodipentene.”’ It may also be prepared
by mixing the solutions of equal weights of dextro- and levo-
carvoximes.* It is further formed as a by-product, together with
carvacrol and hydroxylamine, when isocarvoxime (m. p. 142°) is
boiled with dilute sulphuric acid. It is more sparingly soluble
in all solvents than the active carvoximes, and possesses the same
molecular weight as these.* It melts at 93°. Its chemical be-
havior is the same as that of active carvoxime.

According to investigations of Roozeboom® on the solidifying
points of mixtures of d- and l|-carvoxime, inactive carvoxime
is not a racemic compound, but is a pseudo-racemic mixed
crystal.

Isocarvoxime, C,,H,,NOH, was prepared by Goldschmidt* by
the elimination of hydrobromic acid from hydrobromocarvoxime.
This may be effected by an excess of hydroxylamine or by alco-
holic potash ; small quantities of carvoxime are formed at the
same time. It crystallizes from ligroine in needles, which melt
at 142° to 143°. It is soluble in acids and alkalis, and has more
pronounced basic properties than carvoxime, but, nevertheless,

1Wallach, Ann. Chem., 275, 118.

2Wallach, Ann. Chem., 279, 369.

3Wallach, Ann. Chem., 246, 227.

4Goldschmidt, Ber., 20, 2071.

5Roozeboom, Proc. K. Akad. Wetensch. Amsterdam, 1899, 2, 160.

ee

i Se

RT Ep Vt

HYDROCHLOROCARVOXIME. 191

when treated with sodium alcoholate, it forms a sodium salt
which is insoluble in ether. It combines with hydrochloric acid
to form hydrochlorocarvoxime (Baeyer’). When its ethereal
solution is treated with benzoyl chloride, benzoyl isocarvoxime
results ; it crystallizes in leaflets, and melts at 112°. Isocarvox-
ime and its benzoyl derivative are optically inactive.

Phenylisocyanate unites with isocarvoxime forming carban-
ilido-isocarvorime, C,,H,,.NO-CO-NHC,H,, which melts at
150°.?

When boiled with dilute sulphuric acid it does not yield the
corresponding ketone, but is converted into carvacrol, together
with hydroxylamine and inactive carvoxime. It may be changed
into carvacrylamine by heating with potassium hydroxide at 230°
to 240° (Wallach and Neumann’).

Benzoylcarvoxime, C,,H,,NOCOC,H,, is prepared by treating
an ethereal solution of carvoxime with the calculated quantity of
benzoyl] chloride ; the crystalline mass obtained on evaporation of
the ether is pressed on a porous plate, and purified by recrys-
tallization first from petroleum ether and then from ethyl acetate.
The active modifications melt at 96°, and the inactive derivative,*

prepared from the active compounds, melts at 105° to 106°.

Carvoxime is regenerated by treating benzoyl carvoxime with
sodium alcoholate (Goldschmidt °).

Carbanilidocarvoxime, C,H,NH-CO-ONC,,H,,, is the addition-
product of dextro-carvoxime and phenylisocyanate ; when recrys-
tallized from benzene it forms splendid, brilliant prisms, which
melt at 130° (Goldschmidt’).

Hydrochlorocarvoxime, C,,H,,CINOH, is obtained when a solu-
tion of carvoxime in methyl alcohol is saturated with hydrogen
chloride (Goldschmidt®). It may also be prepared by treating
hydrochlorocarvone with hydroxylamine (Goldschmidt and
Kisser °), or by passing hydrochloric acid gas through an alco-
holic solution of o- or f-limonene nitrosochloride (Wallach ’) ;
compare Baeyer.' The optically active modifications crystallize
from petroleum ether in transparent, lustrous prisms or tablets,
which melt at 135°;’ Baeyer' found the decomposition point
(171°) to be characteristic for this compound.

1Baeyer, Ber., 29, 3.

2Goldschmidt, Ber., 22, 3104.

’Wallach and Neumann, Ber., 28, 1160.
4Wallach, Ann. Chem., 252, 149.
5Goldschmidt, Ber., 18, 1732.
‘Goldschmidt and Kisser, Ber., 20, 488.
7Wallach, Ann. Chem., 270, 178.

192 THE TERPENES.

Racemice hydrochlorocarvoxime, obtained by crystallizing a
mixture of the dextro- and levo-modifications, dissolves readily
in petroleum ether and crystallizes from it in leaflets, which have a

mother-of-pearl luster and melt at 125.5°. According to investi-.

gations of Baeyer,’ inactive hydrochlorocarvoxime is also formed
when isocaryoxime, hydrochlorodipentene nitrosochloride, ter-
pineol nitrosochloride, pinene nitrosochloride or nitrosopinene is
allowed to stand for a long time in an ethereal or alcoholic solu-
tion of hydrochloric acid.

Benzoyl hydrochlorocarvoxime, C,,H,,Cl. NOCOC,H,, results by
warming a solution of hydrochlorocarvoxime in dry ether with the
calculated amount of benzoyl chloride. When recrystallized sev-
eral times from ethyl acetate, the optically active substance melts
at 114° to 115°, while the inactive compound melts at 111°
(Goldschmidt ’*).

Benzoyl hydrochlorocarvoxime is isomeric with benzoyl limo-
nene nitrosochloride ; in the former the elements of hydrochloric
acid are quite firmly fixed, while in the latter they are not so
closely united.

Hydrobromocarvoxime, C,,H,,BrNOH, is produced by saturating
a methyl alcoholic solution of carvoxime with hydrobromic acid,
or by allowing hydrobromocarvone to react with the theoretical
quantity of hydroxylamine (Goldschmidt and Kisser’). Accord-
ing to Baeyer,*? hydrobromocarvoxime may be formed in a manner
analogous to that suggested under hydrochlorocarvoxime, by
treating a-limonene nitrosochloride, pinene nitrosochloride or
terpineol nitrosochloride with an ethereal solution of hydrobromic
acid. ‘The optically active modifications melt and decompose at
133° to 134°; the inactive derivative melts with decomposition
at 128° to 129°; the melting points are not sharp. Hydrobromo-
carvoxime is soluble in alkalis, and may be reprecipitated from
alkaline solutions by acids ; it is very unstable.

Hydroxylaminocarvoxime,* C,,H,,(NH-OH)(NOH), is prepared
by the action of two molecules of hydroxylamine dissolved in
methyl alcohol on carvone, at the ordinary temperature. It
melts at about 60° to 65°, occasionally as high as 83° to 84°;
it boils at 190° at 6 to 7 mm. pressure with considerable decom-
position. The picrate melts at 150° to 151°. The dibenzoyl

1Goldschmidt, Ber., 18, 2222; compare Wallach and Macheleidt, Ann.
Chem., 270, 179.

2Goldschmidt and Kisser, Ber., 20, 2071.

3Baeyer, Ber., 29, 3.

4C. Harries, Ber., 31, 1810; Harries and Mayrhofer, Ber., 32, 1345; see
Wallach and Schrader, Ann. Chem., 279, 366.

ope

a ee

a,

va

SODIUM CARVONEDIHYDRODISULPHONATE. 193

derivative crystallizes from absolute alcohol, and melts at 171° to
172° ; the diphenylcarbimide and diphenylthiocarbimide melt at 96°

to 97°, and 142° to 143°, respectively.

The dioxime, C,,H,,(NOH),, is formed by oxidizing the pre-
ceding compound with mercuric oxide ; it crystallizes from abso-
lute alcohol, melts with decomposition at 193° to 194° when
heated rapidly, and at 188° when the temperature is raised more
slowly. It has the property of reducing Fehling’s solution.
An isomeric compound, C,,H,,N,O,, melting at 153° to 155°, is
obtained from the mother-liquors of the dioxime.

The diketone, C,,H,,O,, results by boiling the dioxime with
dilute sulphuric acid; it crystallizes in large prisms, and melts at
194°. This compound * (1-methyl-4-propeny]l-dihydroresorcinol)
is also formed when carvone, barium hydroxide, and methyl
alcohol are shaken for some time in contact with oxygen (auto-
oxidation of carvone).

Semicarbazones of dextro- and levo-carvone,

crystallize in hexagonal tablets and melt at 162° to 163°. The
semicarbazone of inactive carvone is more sparingly soluble than
the other modifications, and melts at 154° to 156° (Baeyer’).

Carvone semioxamazone,* C_,H,, = N — C,O,N,H,, crystallizes
in aggregates of white needles, and melts at 187° to 188°.

Benzylidene carvone,* C,,H,,0 = CH-C,H,.—Benzaldehyde con-
denses with carvone in the presence of sodium methylate, form-
ing a solid product, which does not cystallize well.

Sodium carvonedihydrodisulphonate,° C,,H,,O - Na,H,S,O,, is

_ formed by boiling carvone with a solution of acid sodium sulphite

and sodium carbonate for about an hour, in a reflux apparatus.
It is a deliquescent, yellowish-white powder, is not decomposed
by alkalis, and yields a semicarbazone, which indicates that the
union of the carvone with the acid sulphite is accomplished by the

ethylene linkages of carvone, while the carbonyl group remains

unchanged. It has been suggested to use this compound in the
estimation of carvone in essential oils. ens

news

Carvone does not yield a normal compound with acid sodium
sulphite.

1Harries, Ber., 34, 2105.

2Baeyer, Ber., 27, 811 and 1923; 28, 640.

3’Kerp and Unger, Ber., 30, 585.

4Wallach, Ber., 29, 1595; Ann. Chem., 805, 274.
5H. Labbé, Bull. Soc. Chim., 23, 1900 (III.), 280.

13

194 THE TERPENES.

Carvone combines with aceto-acetic ester and hydrochloric acid,
forming a compound,’ C,,H,,ClO,, melting at 146°.

Oxymethylene carvone, C,,H,,O = CH(OH), is formed when
d-carvone is dissolved in ether and treated with amyl formate and
sodium, according to Claisen’s method. It is an oil, soluble in
alkalis, is readily decomposed, boils at 132° under a pressure of
12 mm., and gives a deep purple colored solution on the addition
of ferric chloride (Wallach ’).

Reduction Products of Carvone.

When carvone is reduced by means of zine dust and acetic acid,
zinc and sodium hydroxide, or alcohol and metallic sodium, dihy-
drocarvone, C,,H,,O, is formed, together with a crystalline com-
pound, C,,H,,O,, which was at first regarded as a pinacone,’

CoH (OH )—( HO) CH,

Closer investigation, however, proves that this dimolecular re-
duction-product of carvone is not a pinacone, but is a diketone,
and is called dicarvelone.* It exists in nine different modifications,
a dextro-, levo-, and inactive a-dicarvelone, three £-modifications,
and three 7-modifications; only the a-modifications result by the
direct reduction of carvone.

a-Dicarvelones, C,,H,,O,.—These compounds nr ay be prepared
from either dextro- or levo-carvone. Thirty cc. of carvone are
dissolved in 250 cc. of alcohol, and treated with a solution of
twenty-five to thirty grams of potassium hydroxide in 150 ce. of
water, and fifty grams of zinc; after a thorough agitation, the
mixture is warmed on the water-bath for five to six hours. The
excess of zinc is removed by filtration, and the filtrate is distilled
with steam, which removes the alcohol and dihydrocarvone.
The residue in the distilling flask is separated from the water,
extracted with chloroform, and after the addition of some alcohol,
the solution is allowed to evaporate slowly. a-Dicarvelone sepa-
rates in crystals, is washed with a little cold alcohol, and purified
by recrystallization from hot alcohol. The yield is about twenty
to twenty-five per cent. of the carvone employed.

1Goldschmidt and Kisser, Ber., 20, 489.

2Wallach, Ber., 28, 32.

8Wallach and Schrader, Ann. Chem., 279, 379.

4Wallach, Ann. Chem., 305, 223; compare Harries and Kaiser, Ber., 31,
1807.

a

7-DICARVELONES. 195

a-Dicarvelone crystallizes in splendid, rhombic crystals, and the
two active modifications melt at 148° to 149°. D-a-l-Dicarvelone,
prepared from dextro-carvone, is levorotatory, [4] = — 73.92°,
and L-a-d-dicarvelone from levo-carvone is dextrorotatory, [a] p
= + 73.28°. A racemic, inactive a-dicarvelone is obtained by
crystallizing together molecular quantities of D-a-l- and L-a-d-
dicarvelone ; it separates from alcohol in rhombic crystals, and
melts at 120° to 121°.

That a-dicarvelone is a diketone, is proved by the formation of
the phenylhydrazone, C,,H,,(N,HC,H,), ; the hydrazones of the
active modifications melt and decompose at 215°, and the inactive
hydrazone decomposes at about 200°.

a-Dicarvelonoxime, C,,H,,(NOH),, is prepared according to the
method of preparation of carvoxime. The active modifications
melt at 223°, and the inactive derivative melts and decomposes
at 287°. The active acetyl derivatives of the oxime melt at 187°,
and the inactive modification melts at 166°.

a-Dicarvelone dihydrobromide, C,,H,,O,-2HBr.—a-Dicarvelone
contains two ethylene linkages, and unites with two molecules of
hydrogen bromide. The D-a-l-dicarvelone dihydrobromide sepa-
rates from alcohol in white crystals, and melts at 165°.

8-Dicarvelones, C,,H,,O,.— When a-dicarvelone dihydrobromide
is heated with an equivalent amount of alcoholic potash, hydro-.
bromic acid is eliminated, and a compound isomeric with a-
dicarvelone is obtained ; this substance is termed /-dicarvelone.
D-a-l-Dicarvelone dihydrobromide yields a dextrorotatory f-modi-
fication, ia p= + 79.18°, and L-a-d-dicarvelone gives rise
to L-f-l-dicarvelone, [a], = — 82.66°; both active modifica-
_ tions crystallize well, and melt at 207°. By the union of
D-f-d- and L-f-l-dicarvelone, an inactive derivative is produced,
which melts at 168°. The f-dicarvelones form phenylhydrazones,
and also combine with two molecules of hydrogen bromide, form-
ing dihydrobromides, which are identical with the bromides pre-
pared from the a-dicarvelones.

y-Dicarvelones, C,,H,,O,.—These compounds are prepared by
adding the a- or $-dicarvelones, in small portions at atime, to well
cooled, concentrated sulphuric acid ; after standing for a short
time, the product is poured onto ice, the resulting precipitate is
filtered, dried, and crystallized from alcohol. D-;-l-Dicarvelone,
prepared from D-a-l- or D-f-d-dicarvelone, is levorotatory,
[a]p=—213.4° and 201.8°, respectively ; L-y-d-dicarve-
lone is dextrorotatory, [ a], = + 236.8°. Both active modi-
fications melt at 126°, and the inactive y-derivative melts at
112°.

196 THE TERPENES.

The ;-dicarvelones differ from the corresponding a- and f-
compounds in that they do not form phenylhydrazones.

Dieucarvelone, C,,H,,O,.—When hydrochloro- or hydrobromo-
carvone is treated with zinc and potassium hydroxide in a manner
similar to that described in the reduction of carvone, a number of
crystalline products result, among which the compound, C,,H,,O,,
dieucarvelone, melting at 172°, has been isolated and studied ;
the same compound is likewise produced in the reduction of eu-
carvone, C,,H,,O, with sodium hydroxide and zine.

Dieucarvelone melts at 172°, yields a phenylhydrazone and an
oxime, but does not form a solid addition-product with hydro-
bromic acid.

A compound, C,,H,,O,, isomeric with dieucarvelone, is also
formed in the reduction of eucarvone ; it melts at 128°. <A com-
pound, melting at 110° to 112°, is likewise produced in the same
reaction ; it may possibly prove to be identical with inactive 7-
dicarvelone, melting at 112°.

The behavior of carvone towards potassium permanganate has
been studied by Best,‘ and by Wallach,’ but only the most im-
portant results of these investigations will be briefly mentioned
here.

When carvone is treated with aqueous potassium permanganate,
it yields oryterpenylic acid, C,H,,O,, melting at 192.5° ; when this
acid is distilled under diminished pressure, it loses water and
yields a neutral compound, C,H,,O, (dilactone), melting at 129°.
According to Best, oxyterpenylic acid is reduced by hydriodic
acid to terpenylic acid, melting at 55° to 56°. According to
Schryver,® terpenylic acid has the constitution of a lactone of
diaterpenylic acid:

(CH;).C <0 (CH,;),COH
HOCO—CH,—CH—CH,—C H0C0—CH,—¢H—CH,—COOH
Terpenylic acid. Diaterpenylic acid.

According to Wallach, another acid isomeric with oxyterpenylic
acid is formed, together with the latter, by the action of perman-
ganate on carvone; this acid melts at 94° to 95°. (Compare
with Tiemann and Semmler.‘)

10. Best, Ber., 27, 1218 and 3333.

Wallach, Ann. Chem., 275, 155; Ber., 27, 1496.

’Schryver, Journ. Chem. Soc., 63, 1327; Mahla and Tiemann, Ber., 29,
928.

4Tiemann and Semmler, Ber., 28, 2141.

es

CARVEOL METHYL ETHER. 197

The values for the specific rotatory powers of dextro- and levo-
carvone and their derivatives are given in the following table.

Prepared from

Compounds of the Carvone | fextro-car- | Levo-carvone Observer.
Series. vone or leyo- or dextro-
limonene [a] py | limonene [¢] p.

Carvone, +62.00° —62.00° | A. Beyer, Arch. Pharm.,
221, 283.
Carvone hydrogen sul- + 5.53° — 5.55° | A. Beyer, Arch. Pharm.,
phide, 221, 283.
Carvoxime, +39.71° —39.34° | Wallach and Conrady,
Ann, Chem., 252, 148.
Benzoyl carvoxime, +26.47° —26.97° | Wallach and Conrady,

Ann. Chem., 252, 148.

Benzoyl hydrochlorocar- | —10.58° + 9.92° | Macheleidt, Ann. Chem.,
voxime, 270, 179.

2. CARVEOL METHYL ETHER, ©,,H,,OCH,.

When carvone, C,,H,,O, is reduced in an alcoholic solution
with sodium, dihydrocarveol, C,,H,,OH, is formed. An alcohol,
C,,H,,OH, corresponding to carvone is not at present known,
although the methyl ether of carveol, C,,H,,OCH,, has been ob-
tained.

When one hundred grams of limonene tetrabromide are
warmed on the water-bath with a solution of fifteen grams of
sodium in two hundred cc. of methyl alcohol for eight hours, a
compound is produced which has the constitution, C,,H,,BrOCH, ;
it is volatile with steam, boils at 137° to 140° under 14 mm.
pressure, has the specific gravity of 1.251 and the coefficient of
refraction, np = 1.51963, at 18° (Wallach’). .

If a solution of forty-two grams of this compound, C,,H,,BrO-
CH,, in two hundred ce. of ethyl alcohol be treated with thirty-six
grams of sodium, the bromine atom is replaced by hydrogen and
carveol methyl ether results. The reaction-product is distilled in
a current of steam, and the ether, being volatile, is separated from
the distillate by the addition of water ; it is dried with potassium
hydroxide and rectified. :

Carveol methyl ether boils at 208° to 209°, and has a specific
gravity of 0.9065 at 18°; the refractive index is np = 1.47586 at
18°, from which a molecular refraction is calculated that indicates
the presence of two double linkages in the molecule. The ether

1Wallach, Ann. Chem., 281, 129.

198 THE TERPENES.

is optically active, and unites with halogens and halogen hydrides
forming additive products. It yields inactive carvone by oxida-
tion with chromic anhydride in glacial acetic acid solution.

Optically inactive carveol methyl ether may be obtained from
crystalline terpineol (Wallach'). If terpineol dibromide be treated
with hydrogen bromide, it yields a tribromide, which was formerly
designated as 1,2,4-, more recently as 1, 2, 8-tribromoterpane.
When this tribromide is submitted to the action of sodium
methylate, the bromine atom, 2, is replaced by a methoxyl-group,
while the bromine atoms, 1 and 8, are eliminated as hydrogen
bromide :

H, CH; ie

CBr Br

\ ‘

H, H i. ot He HBr

=> =>

H,Q $8, H, CH, H,Q 0H,
H H H
OH OH -

H,; CH, H; CH, H,C - CH,

Terpineol (solid). Terpineol dibromide. 1, 2, 8-Tribromoterpane.
Le

HO ‘a,

Carveol methyl ether.

3, EUCARVONE, ©,,H,,0.

According to Baeyer,? a ketone isomeric with carvone is ob-
tained, when hydrobromocarvone, prepared by the action of
hydrogen bromide on carvone, is treated with alcoholic potash ;
the purification of the hydrobromocarvone is not necessary.
After saturating carvone dissolved in glacial acetic acid with hy-
drobromic acid, the solution is poured into water; the oil which

Wallach, Ann. Chem., 281, 140.
*Baeyer, Ber., 27, 812; compare also Wallach, Ann. Chem., 305, 237.

eS

EUCARVOXIME. 199

separates is washed with water, extracted with ether, and, after
agitating the ethereal solution with sodium bicarbonate, it is care-
fully dried with anhydrous sodium sulphate. This solution is
then well cooled with ice and treated with methyl alcoholic potash
(one part of potassium hydroxide in two parts of methyl alcohol)
until a separation of potassium bromide is no longer noticeable.
The mixture is then poured without delay into cold, dilute sul-
phuric acid ; the ethereal solution is separated, washed with bi-
carbonate of sodium, the ether allowed to evaporate, and the
resulting oil distilled with steam. Eucarvone prepared in this
manner boils at 210° to 215° under ordinary pressure; it is
better, however, to distill in vacuum, since the ketone is partially
decomposed into carvacrol by distillation under atmospheric pres-
sure.

It has an odor differing from that of carvone, but similar to
that of peppermint and of menthone; it is optically inactive,
boils at 104° to 105° (25 mm.) without decomposition, and has
a specific gravity of 0.948 at 20°. Its boiling point and specific
gravity are, therefore, lower than those of carvone. It is quanti-

_tatively converted into carvacrol by heating at its boiling point

for an hour.

Eucarvone derives’ its name from the production of a pure,
deep blue color on boiling a small quantity of the substance in a
test-tube with about two cc. of concentrated methyl alcoholic pot-
ash ; the color is very unstable and disappears at once on the ad-
dition of water.

It does not combine with acid sodium sulphite; it differs from
carvone in that it reacts very slowly with phenylhydrazine, form-
ing an oily phenylhydrazone (Baeyer).

Eucarvoxime, C,,H,,NOH, results by treating an alcoholic solu-
tion of eucarvone with the theoretical quantities of hydroxyl-
amine hydrochloride and sodium bicarbonate. After standing
for one week, the reaction-product is poured onto ice, and eucar-
voxime separates at once in very small crystals. It is obtained
in the form of leaflets by dissolving in alcohol and diluting the
solution with water. It melts at 106°.

According to Wallach,’ the oxime is more readily prepared as
follows. Fifty grams of eucarvone are dissolved in 750 cc. of
ninety per cent. alcohol and to this is added a solution of fifty
grams of hydroxylamine hydrochloride in fifty ce. of hot water.
A concentrated solution of fifty grams of sodiwm hydroxide is
then slowly added, and the liquid is warmed in a flask with re-
flux condenser on the water-bath, for about one hour. After cool-

1Wallach, Ann. Chem., 305, 239.

200 THE TERPENES.

ing, the reaction-product is poured into ice water and acidified with
some acetic acid. The oxime separates at once; it is pressed on
a porous plate, and recrystallized from four times its quantity of
methyl alcohol. It melts at 106°.

It is very stable towards dilute sulphuric acid, and when it is
boiled with this acid for half an hour, only traces of regenerated
eucarvone can be detected by means of methyl alcoholic potash.
It is more readily decomposed into eucarvone by dilute sulphuric
acid if substances are present which combine easily with hy-
droxylamine, for example methy] isonitrosoacetone. It dissolves
in concentrated sulphuric acid without development of heat and
without change. Beckmann’s chromic acid mixture colors crys-
tals of carvoxime black; crystals of eucarvoxime are not af-
fected.

Eucarvone semicarbazone,' C,,H,, = N-NH-CO-NH,, crystal-
lizes in concentric aggregates of prisms, and melts at 183° to
185°.

Condensation-products of eucarvone and benzaldehyde.*—Benzyli-
dene eucarvone, C,H,CH = C,,H,.O, is the chief product obtained
in the condensation of eucarvone and benzaldehyde in alcoholic
solution by means of sodium ethylate. It crystallizes from al-
cohol in well defined, slightly yellowish prisms, melting at 112°
to 113°; it is the normal condensation-product of these two
compounds. A second product is also formed; it has the com-
position, C,,H,,O,, and seems to be formed by the elimination
of one molecule of water from one molecule of eucarvone and
two molecules of benzaldehyde. It crystallizes from a mix-
ture of chloroform and alcohol in white leaflets, and melts at
193° to 194°.

Dieucarvelone,’ C,,H,,O,, is formed in the reduction of eucarvone
with sodium hydroxide and zinc; it melts at 172°. (See under
carvone.)

Eucarvone yields dihydroeucarveol, C,,H,,OH, when it is re-
duced in alcoholic solution with sodium.

Unsymmetrical or gem*-dimethyl succinic acid is formed, to-
gether with a considerable quantity of acetic acid, by the oxida-
tion of eucarvone with a permanganate solution (Baeyer °).

i An alcohol, C,,H,,OH, corresponding to eucarvone is not
nown.

1Baeyer, Ber., 27, 1922.

2Wallach, Ber., 29, 1600; Ann. Chem., 305, 242.
8Wallach, Ann. Chem., 305, 242.

4Baeyer, Ber., 31, 2067.

5 Baeyer, Ber., 29, 3.

—
a: tal

PINOCARVOXIME. 201

4, PINOCARVONE, C,,H,,0.

This ketone was formerly called “‘isocarvone” owing to its sup-
posed similarity to carvone. More recent investigations, however,
have shown that it possesses no similarity with the compounds of
the carvone series, and, accordingly, Wallach’ has changed its
name to pinocarvone. The corresponding alcohol, C,,H,,OH, was
called “‘isocarveol,” but is now designated as pinocarveol.

When pinylamine nitrate is heated with a solution of sodium
nitrite, an alcohol, C,,H,,OH (pinocarveol), is produced ; the latter
yields pinocarvone by oxidation with chromic acid (Wallach ’).

A solution of ten grams of pinocarveol in forty grams of glacial
acetic acid is very gradually treated with a solution of ten grams
of chromic anhydride in a mixture of five cc. of water and ten cc.
of glacial acetic acid. A very vigorous reaction takes place at
once, and, on its completion, the product is distilled with steam ;
the resultant crude ketone is converted into the oxime, and the
latter is purified by steam distillation. Pure pinocarvone is ob-
tained by boiling the oxime with dilute sulphuric acid.

Pinocarvone is a liquid having a characteristic odor, which
differs from that of carvone, but when warm resembles that of
peppermint. It boils at 222° to 224°, and at 19° has the specific
gravity 0.989 ; its refractive index at 19° is 1.506, corresponding
to a molecular refraction of 45.42, which indicates the presence of
two double linkages in the molecule. Since this supposition re-
specting the constitution of pinocarvone has not yet been proved
by chemical methods, and more especially since a transformation of
pinocarvone into carvacrol has not been accomplished, it is possible
that pinocarvone and pinocarveol are not to be regarded as deriva-
tives of dihydrocymene.

It combines with acid sodium sulphite forming a crystalline
compound, which is decomposed by water. It produces a deep
red color when treated with acids.

When pinocarvone is dissolved in alcoholic ammonia and satu-
rated with hydrogen sulphide, pinocarvone hydrogen sulphide is
precipitated as a white, amorphous substance ; it is readily soluble
in chloroform, sparingly in alcohol, and is slowly decomposed by
boiling with caustic soda.

Pinocarvoxime, C,,H,,NOH, is prepared by the action of hy-
droxylamine on crude pinocarvone and is purified by distillation
with steam. It separates from alcohol or ether in well defined
crystals, and melts at 98°.

1Wallach, Ann. Chem., 300, 286.
*Wallach, Ann. Chem., 277, 150; 279, 387.

202 THE TERPENES.

Pinocarvone semicarbazone,’ C,,H,, = N-NH-CO-NH,, is spar-
ingly soluble, and does not crystallize well. It separates from
aqueous methy] alcohol in slightly yellowish crystals, and melts at
204°.

5. PINOCARVEOL, C,,H,,OH.

Pinylamine, C,,H,,NH,, obtained by the reduction of nitroso-
pinene, may be converted into a secondary alcohol, C,,H,,OH,
which is called pinocarveol because of its relation to pinocarvone.

Pinocarveol is prepared according to the following method
(Wallach’).

Twenty grams of pinylamine nitrate are heated with a solu-
tion of ten grams of sodium nitrite in 100 cc. of water for
some time. A yellow oil separates, and is distilled in a current of
steam ; the distillate is shaken with an oxalic acid solution in
order to remove basic compounds, and is again distilled with
steam. The alcohol so obtained is dried over potassium hydrox-
ide, and boils at 215° to 218°.

It has a turpentine-like odor, and a specific gravity of 0.978 at
22°; its refractive power is 1.49787 at 22°, corresponding to the
molecular refraction of 45.55.

6. PINENOL, C,,H,,OH.

According to Genvresse,’ a terpene alcohol, C,,H,,OH, is formed
by passing nitrous acid fumes into well cooled pinene ; the prod-
uct is distilled with steam, and the resulting oil is fractionally
distilled under reduced pressure.

Pinenol is a slightly yellow colored liquid, and possesses an
agreeable odor ; it is insoluble in water, but readily soluble in the
usual organic solvents. It boils at 143° under 38 mm. pressure,
and at 225° under 740 mm.,; it is partially decomposed by distilla-
tion at atmospheric pressure. It has the specific gravity 0.9952
at 0°, and the refractive index, n, = 1.497, from which the molec-
ular refraction 44.563 is calculated ; the theoretical molecular re-
fraction is 44.85, if the presence of one double linkage in the mole-
cule be assumed. Its specific rotatory power is [a] = — 14.66°.

It unites with one molecule of bromine, forming an additive
compound. It is converted into cymene on treatment with phos-
phoric oxide.

Pinenol acetate, C,,H,,O-COCH,, has an odor recalling that of
lavender, and boils at 150° under 40 mm. pressure.

1Wallach, Ann. Chem., 300, 286.

2Wallach, Ann. Chem., 277, 149; 300, 286.
3P. Genvresse, Compt. rend., 130, 918.

<sieaie

twee hee

é

el we eee

LIMONENOL. 203

7, PINENONE, C,,H,,0.

Pinenone' is the ketone corresponding to pinenol, C,,H,,OH,
and results from the oxidation of the latter with a chromic acid
mixture.

It is a yellow liquid, has an agreeable odor, and boils at 132°
(42 mm.); it has a specific gravity 0.9953 at 0°, and is levo-
rotatory, [a],——21.12°. Its refractive index is np = 1.5002,
giving the molecular refraction 44.33; the ealculated value for
the molecular refraction is M = 43.84, if it be assumed that the
molecule contains one double linkage. The ketone is unsaturated,
and adds one molecule of bromine.

Pinenonoxime, C,,H,,:NOH, is produced by heating pinenone
with an alcoholic solution of hydroxylamine. It is also formed in
small quantity during the preparation of pinenol from pinene.

It crystallizes in rhombic crystals, melting at 89°; it boils
with partial decomposition at 170° under a pressure of 40 mm.
It is levorotatory, [ap = — 22.3°.

The dibromide, C,,H,,(NOH)-Br,, melts at 152°. The phenyl
earbimide, C,,H,,,NO-CO-NHC,H,, crystallizes in needles, and
melts at 135°. The benzoyl and butyryl derivatives melt at 105°
and 74°, respectively.

Pinenone semicarbazone, C,,H,,—N—NH-CO-NH,, melts at
82°.

8, LIMONENOL, C,,H,,OH.

This alcohol? is produced by the action of nitrous fumes on
dextro-limonene cooled by a freezing mixture of ice and salt; the

-reaction-product is neutralized with sodium carbonate, distilled

with steam, and the alcohol is then separated from unaltered
limonene by extraction with a concentrated solution of sodium
salicylate, this solvent having the property of dissolving terpene
alcohols, but not terpenes.

Limonenol is a colorless liquid having an agreeable odor, differ-
ing from that of pinenol or limonene. It boils at 135° under a
pressure of 15 mm., has a sp. gr. 0.9669 at 18°, a refractive
index, np=1.497, and a rotatory power, [2] p=+19°21’ at 17°.
Its molecular refraction is 45.99, which corresponds with the cal-
culated value of a compound containing two double linkings. It
absorbs two molecules of bromine without evolution of hydrogen
bromide. On oxidation with chromic acid it yields the ketone,
limonenone, C,,H,,O.

1P. Genvresse, Compt. rend., 130, 918.
2P. Genvresse, Compt. rend., 132, 414.

204 THE TERPENES.

9, LIMONENONE, C,,H,,0.

Limonenone’ is the ketone corresponding to the alcohol, limo-
nenol, and is prepared by oxidizing this alcohol with a chromic
acid mixture.

It is a colorless liquid, having an agreeable odor. At 20° it
has the sp. gr. 0.9606, the refractive index, np = 1.487, and the
specific rotatory power [a], = + 16° 4’. Its molecule contains
two double linkings. |

Limonenonoxime, C,,H,,NOH, is formed by treating the ketone
with alcoholic solutions of hydroxylamine hydrochloride and
potassium hydroxide; it is purified by steam distillation. It
melts at 85.5° ; but after the fused material has solidified, it then
melts at 72°. It is formed in small quantity by the action of
nitrous fumes on limonene.

This compound is perhaps identical with levo-carvoxime, since
the melting point of the latter corresponds with the lower melting
point (72°) of limonenonoxime ; the two compounds have the same
specific rotatory power, [a|,—= — 39° 42’, and their benzoyl
derivatives (m. p. 95°), and phenylearbimides (m. p. 133°) agree
in properties.

10. SABINOL, C,,H,,OH.

The chemists of Schimmel & Co.’ observed that the princi-
pal constituent of the oil of savin is an alcohol, sabinol, which
occurs partly free and partly combined as an acetic acid ester.
It is obtained by the fractional distillation of the saponified oil
of savin, and boils at 210° to 213°, or at 105° to 107° under 20
mm. pressure.

It was at first assumed that sabinol had the composition,
C,,H,,OH, but more recent investigations of Fromm?’ and
Semmler* indicate that its formula is C,,H,,OH.

The fraction of oil of savin boiling at 195° to 235°, when further
fractionated, yields an oil boiling at 222° to 224°, and consisting
largely of the acetate of sabinol. When this acetate is hydrolyzed
with alcoholic potash, sabinol is obtained. The alcohol is more
readily obtained by boiling the crude oil of savin with alcoholic
potash for half an hour, and distilling the product with steam ;
the oil which passes over is purified by repeated fractionation.
The yield is about fifty per cent. of the crude oil.

1P. Genvresse, Compt. rend., 132, 414.

*Schimmel & Co., Semi-Annual Report, Oct., 1895, 44.
3E. Fromm, Ber., 31, 2025.

4F. Semmler, Ber., 33, 1455.

00 -e e oe

SABINYL GLYCEROL. 205

PROPERTIES.—Pure sabinol is a colorless oil, with a faint odor
resembling that of thujone ; it boils at 208° to 209°, has a specific
gravity 0.9432 at 20°, a refractive index, “4, = 1.488, and a mo-
lecular refraction, = 46.5.

Sabinol absorbs bromine, iodine, and hydrogen chloride forming
oily addition-products.

Semmler’ regards it as a pseudo-terpene alcohol. It does not
lose oxygen when heated with zinc dust, nor does it react with
phthalic anhydride. It is probably a secondary alcohol, although
it does not yield the corresponding ketone, C,,H,,O, on oxidation.

It is converted into thujone (tanacetone) by distillation with
zine dust, and, when boiled with absolute alcohol and a few drops
of sulphuric acid, it gives rise to cymene.

Sabinol acetate, C,,H,,O-COCH,, boils at 222° to 224°.

1015
Sabinyl glycerol, C,,H,.(OH),, results on the oxidation of sabinol
with aqueous potassium permanganate at 0° ; it crystallizes from
water, and melts at 152° to 153°. Upon warming with water

containing a trace of acid, it is converted into ewminyl alcohol,

acetogendicarboxylic acid, C,H, ,O,.
On reduction with sodium and amyl alcohol, sabinol yields
thujyl alcohol, C,,H,,OH, which is readily oxidized to thujone.

1Semmler, Ber., 34, 708.

B. SUBSTANCES CONTAINING ONE ETHYLENE LINK-
AGE. KETONES, C,,H,,0, ALCOHOLS, ©,,H,,0H,
AND OXIDES, C,,H,,0.

1. DIHYDROCARVONE, ©,,H,,0.

Dihydrocarvone is a ketone which has not yet been observed
in nature. It was obtained almost simultaneously by Wallach and
Kerkhoff,' and by Baeyer? through the oxidation of dihydrocar-
veol, C,,H,,OH, with chromic anhydride. Wallach and Schrader*®
then showed that it is not necessary to employ the indirect method
through dihydrocarveol in order to secure dihydrocarvone, but
that it may be prepared by the direct reduction of carvone by means
of zinc dust and sodium hydroxide, or zine dust and acetic acid.

Dihydrocarvone is prepared from dihydrocarveol* by dissolving
ten grams of the latter in twenty cc. of glacial acetic acid and
treating the solution with a concentrated, aqueous solution of four
to six grams of chromic anhydride; the mixture is heated in a
flask, fitted with reflux condenser, on a water-bath for about
twenty minutes. The resulting dihydrocarvone is distilled in a
current of steam and purified by the method given below.

For the preparation of dihydrocarvone from carvone, introduce
into a medium sized flask in the order named, one hundred ce. of
water, fifty grams of zinc dust, twenty-five grams of potassium
hydroxide dissolved in fifty cc. of water, twenty cc. of carvone,
and two hundred and fifty ce. of alcohol. Shake vigorously the
contents of the flask, and then boil for four or five hours, with reflux
condenser, on the water-bath. When the smell of carvone can
no longer be recognized, distill off the alcohol, the last portions of
which may carry over some dihydrocarvone. Distill the residue
with steam, and separate the dihydrocarvone from the distillate.

Crude dihydrocarvone, obtained by these methods, always con-
tains some dihydrocarveol as an impurity. It is purified by agi-
tating with a solution of acid sodium sulphite, and, after standing
for twenty-four hours, the resulting crystals are filtered, washed
with a mixture of alcohol and ether, pressed on a porous plate and
decomposed with sodium hydroxide.

1Wallach and Kerkhoff, Ann. Chem., 275, 114.

2Baeyer, Ber., 26, 823.
3Wallach and Schrader, Ann. Chem., 279, 377.

206

DIHYDROCARVONE. 207

Twenty-six to thirty grams of pure dihydrocarvone may be ob-
tained from forty grams of carvone, if the last described method
be employed.

Dihydrocarvone is also obtained by the reduction of hydrobro-
mocarvone.*

PROPERTIES.” —Dihydrocarvone boils at 221° to 222°, and its
vapor has an odor recalling that of menthone, or of carvone ; its
specific gravity at 19° is 0.928 and its refractive index, n, =
1.47174, corresponding to the molecular refraction 45.84. It is
optically active; the product obtained from dextro-carvone or
dextro-dihydrocarveol is levorotatory, while that prepared from
levo-carvone or levo-dihydrocarveol is dextrorotatory (Wallach).

An intramolecular change of dihydrocarvone into an isomeric
ketone, which is identical with the carvenone discovered by Wal-
lach, is effected when dihydrocarvone is treated with concentrated
sulphuric acid at 0° (Baeyer*). The same transformation re-
sults by boiling dihydrocarvone with dilute sulphuric acid (Wal-
lach *), or with formic acid.’ Carvenone is also formed when a
solution of dihydrocarvone in petroleum ether is saturated’ with
hydrogen bromide ;° a small quantity of a bromine derivative is
formed during this reaction, and it may be completely converted
into carvenone on treatment with zine dust.

Carvacrol is formed by boiling this ketone with ferric chloride
(Wallach).

Dihydrocarvone combines with one molecule of hydrogen bro-
mide, forming the oily dihydrocarvone hydrobromide, which, on
treatment with sodium acetate and glacial acetic acid, yields a mix-
ture of dihydrocarvone and carvenone. If, however, a glacial acetic
solution of dihydrocarvone hydrobromide be treated with silver
acetate, the acetyl ester of a ketone-alcohol is produced ; this acetate
boils at 153° to 160° under a pressure of 25 mm., and is converted
into a glycol, C,,H,,(OH),, by hydrolysis and subsequent reduction
with sodium and alcohol. This glycol crystallizes in slender, white
needles, melts at 112°, and is likewise formed when dihydrocarveol
hydrobromide is treated with silver acetate (Baeyer’).

Bromine reacts with dihydrocarvone hydrobromide, forming
dihydrocarvone dibromide (Baeyer).

1Harries, Ber., 34, 1924.

?Kondakoff and Lutschinin, Journ. pr. Chem., 60 (II), 257.

3Baeyer, Ber., 27, 1921.

4Wallach, Ann. Chem., 279, 388.

5Klages, Ber., 82, 1516; compare Kondakoff and Lutschinin, Journ. pr.
Chem., 60 (II), 257.

6Kondakoff and Gorbunoff, Journ. pr. Chem., 56, 248.
TBaeyer, Ber., 28, 1589.

208 THE TERPENES.

Dihydrocarvone hydrochloride,’ C,,H,,O-HCl, is produced by
treating an acetic acid solution of dihydrocarvone with hydrogen
chloride. It boils at 155.5° to 157° under 15 mm. pressure, has
the sp. gr. 1.0266 and refractive index, np = 1.47877, at 20°.
It is converted into carone by boiling with alcoholic soda.

The action of phosphorus pentachloride converts dihydrocar-
vone into a chloride,’ C,,H,,Cl, which boils at 208° under ordi-
nary pressure and at 105° to 106° under 16 mm. pressure ; it
has the sp. gr. 1.025 and the refractive index, np = 1.51622, at
18°. It is possibly identical with the chloride obtained by a
similar treatment of carvenone.

Dihydrocarvone dibromide, C,,H,,BrO- HBr, is obtained, when
two atoms of bromine are added to a cold solution of dihydrocar-
vone in glacial acetic acid containing hydrobromic acid.

The reaction-product is poured into ice-water, and the dibro-
mide, which separates, is crystallized from ether or methyl alcohol ;
it forms brilliant crystals. The active modifications melt at 69°
to 70°. The racemic derivative, obtained by recrystallizing a
mixture of equal weights of the dextro- and levo-compounds,
melts at 96° to 97° (Wallach®).

Inactive dihydrocarvone dibromide is also formed by bromina-
tion of the trioxyhexahydrocymene (m. p. 121° to 122°), which
is obtained by oxidation of terpineol. Ten grams of trioxyhexa-
hydrocymene are suspended in glacial acetic acid, allowed to stand
with fifty cc. of a saturated solution of hydrogen bromide in glacial
acetic acid for three or four hours, and then treated with nine ce.
of bromine ; the dibromide is precipitated by pouring the reaction-
mixture into ice-water, and recrystallized from ether ; it separates
in triclinic crystals, melting at 96° to 97°.

Baeyer*‘ has further observed the formation of dihydrocarvone
dibromide in the following reactions.

1. Bisnitroso-4-bromotetrahydrocarvone is obtained, when di-
hydrocarvone hydrobromide (two grams) is treated at a low tem-
perature with a mixture of ethyl nitrite (1.3 grams) and a few
drops of acetyl chloride; its active modifications melt at 131°,
and its inactive derivative melts at 142°. Inactive dihydrocar-
vone dibromide (m. p. 96° to 97°) is formed, together with another
product, by the action of a saturated glacial acetic acid solution
of hydrobromic acid on the inactive modification of the bisnitroso-
compound.

1Kondakoff and Gorbunoff, Journ. pr. Chem., 56, 248.
2Klages and Kraith, Ber., 32, 2550. ;

3Wallach, Ann. Chem., 286, 127.

4Baeyer, Ber., 28, 1589.

DIHYDROCARVOXIME. 209

2. Inactive bisnitrosocarone yields caronbisnitrosylic acid and
inactive dihydrocarvone dibromide on treatment with a glacial
acetic acid or alcoholic solution of hydrobromic acid. This ex-
periment was also performed by Baeyer with the optically active
modifications.

1 : 8-Oxybromotetrahydrocarvone,' C,,H,,Br(OH)O, is produced
in the form of its sodium derivative when dihydrocarvone dibro-
mide (1: 8-dibromotetrahydrocarvone) is diluted with ether and
treated with a solution of sodium hydroxide (sp. gr. 1.28) ; the
sodium salt is decomposed with dilute sulphuric acid. It crystal-
lizes from dry ether in large prisms, melts at 69° to 72°, is optic-
ally active, and is rather unstable, being decomposed both by acids
and alkalis. Methyl alcoholic potash converts it into orycarone,
C,,H,,O,, When it is recrystallized from methyl alcohol, a small
quantity of an isomeric compound, melting at 136° to 138°, i is
obtained. If oxybromotetrahydrocarvone be allowed to remain
in contact with water or dilute acids, it is converted into an optic-
ally active keto-terpine, C,,H,,(OH),O, melting at 78° to 80°.

Dihydrocarvone tribromide, C,,H,,OBr,, is produced by the action
of one molecular proportion of bromine on a glacial acetic acid
solution of dextro- or levo-dihydrocarvone dibromide ; its active
modifications form hemihedral orthorhombic crystals, and melt at
88° to 89°, while the racemic derivative melts at 65° (Wallach ’).

Dihydrocarvone dichloride, C,,H,,ClO-HCl, is prepared like the
dibromide by treating bisnitrosocarone, or the bisnitroso-com-
pound obtained from dihydrocarvone hydrochloride, with alcoholic
hydrochloric acid. The optically active derivatives melt at 42°,
and the inactive modification melts at 66° to 68° (Baeyer *).

Dihydrocarvoxime, C,,H,,NOH, was prepared by Wallach and
Kerkhof! A warm solution of six grams of hydroxylamine
hydrochloride in six ce. of water is added to the warm solution of
six cc. of dihydrocarvone in twenty-five ce. of alcohol ; six grams
of potassium hydroxide dissolved in five cc. of water are then
_ added, with constant agitation, and the cold reaction-product is
* poured into a large quantity of cold water. The oxime so formed
crystallizes on the slow evaporation of an alcoholic solution in
thick prisms, and melts at 88° to 89°. A physical isomeric
modification,’ which separates in more difficultly soluble needles,
is always formed, together with the oxime crystallizing in prisms.

1Baeyer and Baumgiirtel, Ber., 31, 3208.
2Wallach, Ann. Chem., 286, 127.

3Baeyer, Ber., 28, 1589.

4Wallach and Kerkhoff, Ann. Chem., 275, 116.
5Wallach, Ann. Chem., 279, 381.

14

210 THE TERPENES.

Dihydrocarvoxime is dextro- or levorotatory according as it
originates from dextro- or levo-dihydrocarvone. The inactive
oxime is prepared by recrystallizing a mixture of the two active
modifications, and melts at 115° to 116°; thus, inactive dihy-
drocarvoxime, like inactive carvoxime, has a higher melting point
than the active derivatives :—

ACTIVE. INACTIVE.
Carvoxime, 72° 93°
Dihydrocarvoxime, 88° to 89° =—s-_:- 115° to 116°

Dihydrocarvoxime hydrobromide, C,,H,,BrNOH, is formed by
the treatment of dextro- or levo-dihydrocarvoxime with a glacial
acetic acid solution of hydrobromic acid ; it crystallizes from ether
or ethyl acetate in flat prisms or tablets, and melts and decom-
poses at 109° (Wallach ’) ; according to Baeyer,’ it melts at 118°
to 120°.

According to Wallach,’ when this hydrobromide melts, it loses
water, becomes yellow, and again solidifies. This process is ac-
companied by a conversion of the substance into carvacrylamine
hydrobromide ; this change may also be effected by boiling a so-
lution of dihydrocarvoxime hydrobromide in xylene :—

An oxime, which Baeyer? at first called ‘‘ carveoloxime,” and
which was not isolated in a condition of purity, is obtained when
dihydrocarvoxime hydrobromide is subjected to the action of me-
thyl alcoholic potash in the cold. This oxime, however, is iden-
tical with the oxime of carvenone; when it is boiled with sul-
phurice acid, carvenone is obtained, and may be identified by
conversion into carvenone semicarbazone, which melts at 202° to
205°. This transformation of dihydrocarvoxime into carven-
onoxime is analogous to the conversion of dihydrocarvone into
carvenone, which was observed by Baeyer.

In consideration of Baeyer’s experiments, it would be antici-
pated that an isomeric oxime,’ which Wallach obtained by the ac-
tion of concentrated sulphuric acid on dihydrocarvoxime, would
be identical with the oxime of carvenone. This does not seem to
be the case, for this isomeric oxime melts at 87° to 88° (carven-
onoxime melts at 91°), and Wallach mentions nothing regarding
the identity of this compound with the oxime of carvenone,*
which he had previously prepared.

1Wallach, Ann. Chem., 279, 381.

2Baeyer, Ber., 27, 1921.
3Wallach, Ann. Chem., 277, 126.

DIHYDROCARVEOLACETIC ACID. 211

Semicarbazone of dihydrocarvone, C,,H,; = N-NH-CONH,,
melts at 189° t0 191°. The melting point is not sharp (Wallach’).

Benzylidene dihydrocarvone,” C,,H,,O = CH -C,H,, is the con-
densation-product obtained from benzaldehyde and dihydrocar-
vone ; it is an oil, boiling at 187° to 190° under 10 mm. pressure.
It yields an oxime, which crystallizes from methyl alcohol in color-
less needles, and melts at 145° to 146°.

Benzyldihydrocarveol,’? C,,H,,(OH) -CH,C,H,, is formed by the
reduction of the preceding compound with alcohol and sodium ;
it boils at 182° to 183° at 10 mm. The action of phosphoric
anhydride converts it into the hydrocarbon, C,,H,,, which boils at
166° to 169° under 10 mm. pressure.

Oxydihydrocarvone,*® C,,H,,(OH)O, is produced by the oxida-
tion of pinole hydrate with chromic acid in glacial acetic acid
solution. Its semicarbazone melts at 174°, and its ovime crystal-
lizes from alcohol and melts at 133° to 134°. Oxydihydrocar-
voxime is likewise obtained by the elimination of hydrochloric
acid from terpineol nitrosochloride ; it yields a diacetyl derivative,
melting at 107°. Dilute sulphuric acid converts the oxime into
inactive carvone, while concentrated acid gives rise to amido-
thymol. ‘

Dihydrocarveolacetic acid,* C,,H,,(OH) .CH,- COOH, boils at
196° to 208° under 14 mm. pressure; when distilled under or-
dinary pressure, it yields an unsaturated hydrocarbon which is
possibly to be regarded as homolimonene. The ethyl ester, pre-
pared from dihydrocarvone and ethyl bromoacetate, boils at 150°
to 170° (14 mm.) and at 282° to 288° under atmospheric pres-
sure ; it has a sp. gr. 0.997 and np = 1.47664 at 20°.

The owymethylene derivative of dihydrocarvone, C,,H,,O =

CHOH, is an oil, boiling at about 115° at 15 mm. pressure
(Wallach’).

Dihydrocarvone is converted into a diketone, C,H,,O,, on oxi-
dation with chromic anhydride ; it boils at 152° to 160° under a
pressure of 22 mm. Its diovime crystallizes in two modifications,
one of which is sparingly soluble and melts at 197° to 198°, and
the other is readily soluble and melts at 175° to 176° (Tiemann
and Semmler*). This diketone corresponds to the ketone-alcohol,
C,H,,0,, which is obtained by oxidation of dihydrocarveol.

1Wallach, Ber., 28, 1955.

?Wallach, Ann. Chem., 305, 268.
3Wallach, Ann. Chem., 291, 342.
4Wallach, Ann. Chem., 314, 147.
5Wallach, Ber., 28, 33.

Tiemann and Semmler, Ber., 28, 2141.

212 THE TERPENES.

Wallach and Scharpenack ' oxidized dihydrocarvone with dilute
permanganate solution, and obtained the following products.

1. A ketone-glycol, C,,H,,O(OH),, which melts at 115° to 120°,
and boils at 130° under 10 mm. pressure; it forms a semicarba-
zone, melting at 202°. Dilute sulphuric acid converts this com-
pound into a ketone (C,,H,,0 ?), boiling at 220°.

2. A diketone, C,H,,O,, which is probably identical with the di-
ketone described by Tiemann and Semmler (see above), but it
solidifies when placed in a freezing mixture. Its dioxime melts at
195°, and its semicarbazone at 203° to 204°.

3. Ovzalic acid, and an acid melting at 203° to 204°.

The reduction of carvone with zine dust and sodium hydroxide
yields as a by-product, dicarvelone, C,,H,,O, (see under carvone).

It should also be recalled that the ketone,’ C,,H,,O, obtained in
the reduction of nitrosopinene dibromide with zinc and acetic acid,
is identical with inactive dihydrocarvone; it gives an oxime,
melting at 113° to 114°.

2. DIHYDROCARVEOL, C,,H,,OH.

Leuckart* determined that an alcohol is formed by the reduc-
tion of carvone in an alcoholic solution with sodium. A more
detailed investigation of this compound by Lampe‘ led to the re-
sult that it is not carveol, C,,H,,OH, as Leuckart had believed,
but that it has the constitution, C,,H,,OH, and must therefore be
regarded as dihydrocarveol. Lampe’s observations have since
been confirmed by the researches of Wallach, Kruse, and Kerkhoff.®

Dihydrocarveol is prepared by the reduction of either dextro-
or levo-carvone with sodium and alcohol, according to Wallach’s
method of preparing borneol from camphor.

Twenty grams of carvone are dissolved in 200 cc. of absolute
alcohol, and twenty-four grams of sodium are added rather rap-
idly. Towards the end of the reaction it is generally essential to
add more alcohol or water in order to effect the complete solution
of the sodium, and the product is then distilled with steam. As
soon as the distillate appears cloudy the receiver is changed ;
dihydrocarveol distills over rather slowly, and is then separated,
dried with potassium hydroxide, and rectified. The dihydro-
carveol, which remains dissolved in the aqueous-alcoholic distillate,
may be recovered by adding common salt and extracting with ether.

1Wallach and Scharpenack, Ber., 28, 2704.
2Wallach, Ann. Chem., 300, 291; $13, 3465.
3Leuckart, Ber., 20, 114.

4Lampe, Inaug. Diss. Goéttingen, 1889.

5Wallach, Kruse and Kerkhoff, Ann. Chem., 275, 110.

METHYL DIHYDROCARVYLXANTHATE. 213

The formation of dihydrocarveol from dihydrocarvylamine is
mentioned below.

PropertiIES.—Dihydrocarveol has an agreeable odor, recalling
that of terpineol. It boils at 224° to 225° at ordinary pressure,
and at 112° under a pressure of 14 mm. At 20° it has a spe-
cific gravity of 0.927 and a refractive index, np = 1.48168, cor-
responding to the molecular refraction of 47.33; it rotates the
plane of polarized light in the same direction as the carvone from
which it is derived.

It behaves as an unsaturated compound towards bromine and
the halogen hydrides. In its reaction it exhibits a great simi-
larity to terpineol, with the one exception that the latter is a ter-
tiary alcohol, which, in contrast to dihydrocarveol, does not yield
a ketone on oxidation with chromic anhydride. Like terpineol,
it is converted into terpenes by treatment with dehydrating
agents; terpinene is formed when dihydrocarveol is boiled with
dilute sulphuric acid. It has not been ascertained with certainty
whether, under other conditions, different terpenes are formed, but
it is highly probable that they are.

Dihydrocarveol is produced, together with dipentene,’ when an
aqueous solution of equal molecular proportions of dihydrocarvyl-
amine hydrochloride and sodium nitrite is heated.

Dihydrocarvyl phenylurethane,

/ NEOs
C= 0
NOCH:

-is obtained when theoretical quantities of carbanile and dihydro-
carveol are brought together. After a few days the mixture be-
comes very thick, and eventually solidifies; it is washed with
ligroine, and recrystallized from dilute alcohol. The urethanes
obtained from the active modifications of dihydrocarveol melt at
87°; the racemic compound, formed by the combination of the
active derivatives, is more readily soluble in alcohol than its com-
ponents, and melts at 93°.

Methyl dihydrocarvylxanthate,? C,,H,,O-CS,-CH,, is produced
by successively treating dihydrocarveol, dissolved in dry toluene,
with sodium, carbon bisulphide, and methyl] iodide; it is a thick,
yellow oil. On distillation, it yields a mixture of limonene and
another hydrocarbon.

1Wallach, Ann. Chem., 275, 128.
2L. Tschigaeff, Ber., 33, 735.

214 THE TERPENES.

Dihydrocarvyl acetate, C,,H,,OCOCH,, results on boiling dihy-
drocarveol with acetic anhydride; it is a liquid, boiling at 232°
to 234°, is readily oxidized by permanganate, and is converted
into a hydriodide by the action of hydriodic acid in a glacial
acetic acid solution. This hydriodide yields tetrahydrocarvy]l
acetate by reduction with zinc dust and glacial acetic acid ; the
latter is converted into tetrahydrocarveol, C,,H,,OH, by hydrol-
ysis (Baeyer’).

Dihydrocarveol hydrobromide, C,,H,,OH-HBr, is formed by the
action of a glacial acetic acid solution of hydrogen bromide on
dihydrocarveol ; it is a heavy oil, and, when treated with silver
acetate, it yields an acetate, boiling at 150° to 155° under a
pressure of 15 mm.; this acetate may be converted by hydrolysis
into a glycol, C,,H,,(OH),, which is soluble in water and alcohol,
and melts at 110.5° to 112°. When oxidized with chromic acid,
this glycol is converted into a liquid oxytetrahydrocarvone, whose
semicarbazone melts at 139° (compare under dihydrocarvone and
carone).

Wallach? has published a preliminary notice concerning the
oxidation of dihydrocarveol with potassium permanganate. He
found that dihydrocarveol is oxidized into a trioxyhexahydrocy-
mene; the product is a viscous liquid, and may be distilled with-
out decomposition in vacuum. When trioxyhexahydrocymene is
warmed with dilute sulphuric acid, it yields a ketone, C,,H,,O,
boiling at 196° to 199°; its specific gravity at 20° is 0.962, and
its refractive index, n»=1.484. This ketone unites with nitrosyl
chloride, forming a deep blue oil, and combines with hydrobromic
acid, giving a solid addition-product.

This compound, C,,H,,O, was at first regarded as an unsatu-
rated oxide ; but, in the light of further investigation, it appears
to be a ketone allied to pulegone, since it reacts with hydroxyl-
amine yielding a mixture of two hydrated oximes, C,,H,, NOH+
H,O, one of which melts at 111° to 112°, and the other at 164°
to 165°.

Tiemann and Semmler* have investigated in another direction
respecting the constitution of the trioxyhexahydrocymene obtained
by Wallach. By treating this substance with very dilute chromic
acid, they obtained a ketone-alcohol, C,H,,O,, which melted at
58° to 59°; on oxidizing this ketone-alcohol with a solution of
bromine in sodium hydroxide, it was converted into an acid,

C,H,,0 - COOH, which melted at 153°. When heated with bromine

1Baeyer, Ber., 26, 821.
2Wallach, Ann. Chem., 275, 155; 277, 151; 279, 386.
’Tiemann and Semmler, Ber., 28, 2141.

DIHYDROCARVEOL HYDROBROMIDE. 215

(six atoms) at 190°, the acid was changed into meta-oxy-para-
toluic acid, together with a small quantity of para-toluic acid,
thus corresponding to the observations of Einhorn and Willstitter
respecting the behavior of hydro-aromatic acids. From these
facts, Tiemann and Semmler have proposed the following consti-
tutional formulas of trioxyhexahydrocymene and its oxidation
products :

'H, Hs
H
H, OH H, HOH
H, H, H, H,
HH H
H O
H; 20H CH,
Trioxyhexahydrocymene Methyl-1-ethyl-on-4-
from dihydrocarveol. cyclohexanol-6
(m. p. 58° to 59°).
Le
[ 3 JH;
H
H, HOH H OH
H, H, H H
A 7
OH ‘COOH
Methyl-1-cyclohexanol-6- m-Oxy-p-toluic acid.
methyl-acid-4 (m. p.
153°).

Tiemann and Semmler believe that they have thus explained
the constitution of dihydrocarveol and of carvone, and conse-
quently that of limonene; they ascribe the following formulas to
these compounds :

A, 3 Hy
H
| 4~N
H,¢ HOH H iH a
H,Q OH, H,C OH, HQ CH,
H

JH H

S \
H; H, H;,C CH, H,C CH,
Dihydrocarveol. Carvone. Limonene.

216 THE TERPENES.

These formulas, which are the natural consequence of the
formula of terpineol founded on the researches carried on by
Wallach,’ and, directly following him, by Tiemann and Semmler,’”
had been presented by G. Wagner* one year previous to their
publication by Tiemann and Semmler.

3. CARVENONE, C,,H,,0.

Crystallized terpineol (melting point 35°) yields a trivalent
alcohol, C,,H,,(OH),, on oxidation with potassium permanganate.
_ This substance melts at 121° to 122° and, when heated with dilute
sulphuric acid, is converted into cymene and a compound, C,,H,,O
(Wallach *):

C,,H, (OH), es 3H,O ve C,,.Hiy
C,H, (OH jem 2H,0 ms C,,H,,0.

Wallach supposed that a monovalent, unsaturated alcohol,
C,,H,,OH, belonging to the carvone series, might be formed, to-
gether with cymene, from this trivalent alcohol, and that it should be
designated as carveol. Nevertheless, he at once determined that
the substance which he had obtained was not an alcohol, but reacted
like a ketone ; a name was not immediately given to this ketone.

The same ketone, C,,H,,O, was subsequently obtained by
Baeyer,° who gave to it the provisional name “carveol.” After

further examination Wallach ° called it carvenone.

~ Carvenone also results when dihydrocarvone is treated with cold,
concentrated sulphuric acid, and the resulting solution is precipitated
with ice (Baeyer*); or, when dihydrocarvone is boiled with dilute
sulphuric acid(Wallach®). It may likewise be produced from carone,
since dihydrocarvone unites with hydrobromic acid forming an ad-
ditive compound from which hydrogen bromide may be withdrawn,
yielding carone ; when the latter is heated for some time in a flask
with reflux condenser, carvenone is formed (Baeyer’°).

According to Klages,’ carvenone is produced when dihydrocar-
vone is heated with formic acid in a reflux apparatus.

Carvenone is the intermediate product formed in the conversion
of camphor into cymene and into carvacrol. Carvenone is also

1Wallach, Ber., 28, 1773.

2Tiemann and Semmler, Ber., 28, 1778.

8G. Wagner, Ber., 27, 1653 and 2270.

4Wallach, Ann. Chem., 277, 110 and 122.

5Baeyer, Ber., 27, 1917.

6Wallach, Ann. Chem., 286, 129.

TA. Klages, Ber., 32, 1516; compare Kondakoff and Gorbunoff, Journ.

pr. Chem., 56, 248; Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.],
257.

NITROSOCARVENONE. 217

produced by the action of concentrated sulphuric acid on camphor
at 105° to 110° (Bredt’).

According to Bredt,’ carvenone may be separated from the
more volatile constituent of “ camphrene” ? (a mixture obtained by
the action of hot, concentrated sulphuric acid on camphor).

Carvenone, prepared according to Wallach from the oxidation
product of terpineol and separated by fractional distillation from
cymene and other by-products, has the following properties : it
boils at 231° to 233°, has a specific gravity at 20° equal to
0.929, and a specific refractive power, np = 1.48197.

Wallach* found that carvenone, regenerated from its semicar-
bazone, boils at 232° to 233°, and has the specific gravity 0.927
_at 20°; its refractive index is ny = 1.48217 at 20°, from which
the molecular refraction of 46.76 is calculated, indicating that
the molecule of carvenone contains two ethylene linkages.

It has a slight odor of carvone, but when it is rubbed on the
skin, a peppermint-like odor is noticeable. It does not combine
with acid sodium sulphite. Itis converted into carvacrol by boil-
ing with ferric chloride (Wallach).

Carvenonoxime,C,,H,,NOH, is produced when carvenone is treated
with hydroxylamine hydrochloride ; it is purified by distillation in
a current of steam, and crystallized from methyl alcohol. It forms
transparent, thick prisms, and melts at 91°. Carvenone is regen-
erated by warming the oxime with dilute sulphuric acid.

A compound, C,,H,,N,O,, melting at 162° to 163°, is formed,
together with carvenonoxime, if an excess of hydroxylamine
hydrochloride be allowed to react with carvenone.

Carvenone unites with four atoms of hydrogen when it is re-
duced with sodium and alcohol, and forms tetrahydrocarveol,
C,,H,,OH (Wallach). This secondary alcohol is identical with
Baeyer’s carvomenthol, and is an isomeride of position of menthol.

Carvenone semicarbazone, C,,H,, = N-NH-CO-NH,, crystal-
. lizes in spindles or six-sided leaflets, melting at 202° to 205°
(Baeyer*). According to Wallach, carvenone yields two isomeric
semicarbazones, one of which is a sparingly soluble a-semicarba-
zone, melting at 200° to 201°, and the other a readily soluble
f-semicarbazone, melting at 153° to 154°.

Nitrosocarvenone, C,,H,,O-NO, is prepared by adding ten drops
of strong hydrochloric acid to a mixture of seven grams of car-
venone and five grams of amyl nitrite, well cooled by a freezing

1Bredt, Rochussen and Monheim, Ann. Chem., 3/4, 369.
2Armstrong and Kipping, Journ. Chem. Soc., 63, 77.
3Wallach, Ber., 28, 1955.

4Baeyer, Ber., 27, 1915.

218 THE TERPENES.

mixture; the addition of the acid should require about three
hours. A colorless, crystalline powder separates, which is diffi-
cultly soluble in alcohol; itis purified by precipitating its solution
in chloroform with methyl alcohol. It melts with decomposition
at 133°, and is to be regarded asa bisnitroso-compound (Baeyer").

Condensation-product of carvenone and benzaldehyde.?— W hen
dry hydrogen chloride is passed into a well cooled mixture of two
molecular proportions of benzaldehyde and one of carvenone, the
compound, C,,H,,O,:HCl, is obtained; it separates from acetic
ether in colorless crystals, and melts with decomposition at 197°.
When this substance is heated in vacuum for a short time and is
then distilled, hydrogen chloride is eliminated and the compound,
C,,H,,O,, results; it crystallizes from hot methyl alcohol, and
melts at 170° to 171°.

Oxidation Products of Carvenone.®

When carvenone is oxidized with a two per cent. alkaline solu-
tion of potassium permanganate (three atoms of oxygen to one
molecule of carvenone) some lower fatty acids are formed, to-
gether with the following chief products.

1, a-Oxy-a'-methyl-a-isopropyl adipic acid, C,,H,,O,, is the chief
oxidation product ; it crystallizes from water, and melts at 136°
to 137°. When heated above its melting point, it loses water and
yields a lactonic acid, C,,H,,O,, melting at about 100°.

2. 2:6-Dimethyl-heptan-5-onoic acid, C,H,,O,, is a very feeble
acid; it is an oil, boiling at 166° to 168° under 14 mm. pres-
sure. It is also formed by the gentle oxidation of the acid
C,,H,,0,. Itisa ketonic acid and yields an oxime, C,H,,O,(NOH),
which is sparingly soluble in water and melts at 67° to 68°.

3. a-Methyl glutaric acid—This is also formed, together with
acetone, by the oxidation of the preceding acid, C,H,,O,.

In consideration of these oxidation products, Tiemann and’
Semmler suggest the following formula for carvenone :

H,
de

o¢ 0H,

HQ OH,
H

H,¢ CH,

1Baeyer, Ber., 28, 646.
2Wallach, Ann. Chem., 305, 270.
’Tiemann and Semmler, Ber., 31, 2889.

a ra

CARONE. 219

It should further be mentioned that Marsh and Hartridge?
have described a compound, C,,H,,O, under the name “‘carvenol”’;*
they prepared it by the action of concentrated sulphuric acid on
chlorocamphene, C,,H,,Cl, (obtained by the action of phosphorus
pentachloride on camphor). It seems quite probable that this
“carvenol” is identical with carvenone. On reduction, “ car-
venol” yields a saturated alcohol, C,,H,,OH, “ carvanol,” which
is converted into the ketone, C,,H,,O, “ carvanone,” by oxidation.
The properties of these compounds agree so completely with
those of tetrahydrocarveol and tetrahydrocarvone, that it is
probable that they are identical.

4, CARONE, C,,H,,0.

Carone, like its isomeride carvenone, was obtained by Baeyer’
by the intramolecular change of dihydrocarvone.

In order to prepare it, dihydrocarvone is allowed to stand with
an excess of a glacial acetic acid solution of hydrogen bromide for
fifteen minutes; the resulting dihydrocarvone hydrobromide is
precipitated with ice, and extracted with ether. The ethereal
solution is washed with bicarbonate of sodium, dried over anhy-
drous sodium sulphate, and carefully treated with alcoholic
potash, the mixture being well cooled with ice. When all of the
bromine is removed, the reaction-product is poured onto ice and
sulphuric acid, the ethereal solution is separated, and treated with
a solution of permanganate until the violet color remains per-
manent, in order to remove small quantities of unsaturated by-
products ; the ether is then allowed to evaporate.
~ Carone is a colorless oil having an odor resembling that of
camphor and of peppermint, and similar to that of eucarvone only
not as pronounced. It boils at about 210°, but an accurate de-
termination of its boiling point can not be made owing to its
transformation into carvenone. Carone prepared from caraway
oil is dextrorotatory, having the specific rotatory power, ap =
+173.8°; levo-carvone yields levo-carone, a) = — 169.5°
(Brihl?).

It does not combine with acid sodium sulphite ; it is converted
into carvenone and certain condensation-products by continued

1March and Hartridge, Journ. Chem. Soc., 73, 852; March and Gardner,
Journ. Chem. Soc., 71, 290, refer to this compound as “ camphenol ”;
see Bredt, Ann. Chem., 314, 369.

2Baeyer, Ber., 27, 1915.

3Briihl, Ber., 28, 639.

220 THE TERPENES.

boiling. The latter reaction resembles that observed by Semmler
in the transposition of tanacetone into carvotanacetone.

Carone is very stable towards potassium permanganate, and
its chloroform solution is only very slowly attacked by bromine.
A liquid dibromide results by the action of bromine (two atoms)
on a solution of carone in chloroform ; the bromine is slowly ab-
sorbed without evolution of hydrogen bromide, hence the product
is probably an additive compound.

Carone dissolved in acetic acid unites with hydrobromic acid,
forming an oil which reacts with hydroxylamine and yields dihydro-
carvoxime hydrobromide (m. p. 118° to 120°); this reaction in-
dicates that the oil is dihydrocarvone hydrobromide (Baeyer).

Oxytetrahydrocarvone is formed by the addition of the elements
of water to carone, when the latter is allowed to stand with dilute
sulphuric acid and alcohol for several hours ; when this oxytetra-
hydrocarvone is reduced with sodium and alcohol, it is con-
verted into the same glycol, melting at 112°, which is obtained
by heating dihydrocarveol hydrobromide with silver acetate
(Baeyer *).

Caronoxime, C,,H,,NOH.—The oximes of the optically active
modifications of carone are liquids. An inactive caronoxime is
obtained by mixing the solutions of equal quantities of the oximes
having opposite rotatory powers ; it separates in crystals, melting
at 77° to 79°. When the inactive oxime is reduced in an alco-
holic solution with sodium, carylamine is formed (Baeyer’).

The semicarbazones of dextro- and levo-carone are readily sol-
uble in alcohol, and crystallize in long needles, which melt at
167° to 169°; the inactive semicarbazone forms very insoluble,
small, acute prisms, and melts at 178°. The semicarbazones de-
compose at once into semicarbazide and carone on boiling with
dilute sulphuric acid.

Bisnitrosocarone, (C,,H,,O),N,O,, is obtained by a method sim-
ilar to that employed by Baeyer and Manasse in the: preparation
of nitrosomenthone.

Forty drops of acetyl chloride are cautiously added to a well
cooled mixture of twenty grams of carone and fifteen grams of
amyl nitrite. Crystals separate, and are washed with methyl
alcohol ; the yield is forty-five per cent. of the theoretical.

Bisnitrosocarone is readily soluble in chloroform, sparingly in -

alcohol and ether. The active modifications melt and decompose
at 112° to 118°; the inactive derivative is more difficultly sol-

1Baeyer, Ber., 29, 3.
2Baeyer, Ber., 27, 3485; 28, 640.

i
f
|

—_

yes

» OXYCARONE. 294 |

uble in chloroform, and melts with decomposition at 145°
(Baeyer’).

Baeyer’s original publication must be referred to for a descrip-
tion of other derivatives of bisnitrosocarone. The treatment of
bisnitrosocarone with alcoholic hydrobromic or hydrochloric acid
has already been mentioned ; by means of this reaction Baeyer?
obtained caronbisnitrosylic acid, C,,H,,O-N,O,-H, together with
dihydrocarvone dibromide or dichloride.

The oxymethylene compound of tetrahydrocarvone? is formed in-
stead of the oxymethylene derivative of carone, when carone is
treated with amyl formate in an ethereal solution.

Oxycarone,* C,,H,,O,, is produced when one molecule of 1 : 8-
oxybromotetrahydrocarvone, C,,H,,Br(OH)O (prepared from
dihydrocarvone dibromide), is treated with a methyl alcoholic
solution of potassium hydroxide (1.5 molecules); it is a viscous
oil, boils at 134° to 135° under 19 mm. pressure, and dis-
solves readily in water, the solution having a feebly acid re-
action. Its owime crystallizes in prisms, and melts at 138° ; its
semicarbazone forms needles, melting at 197°, and its phenylure-
thane crystallizes in prisms, melting and decomposing at 190°.

Oxycarone is optically active. Hydrobromic acid converts it
into dibromotetrahydrocarvone, and hydrochloric acid yields the
corresponding dichloro-derivative, melting at 41° to 42°.

The keto-terpine, C,,H,,(OH),O, is readily formed by treating
oxycarone with ice-cold, dilute sulphuric acid, neutralizing the
solution with sodium carbonate, and extracting with ether and
alcohol. It crystallizes from ether in prisms, melts at 78° to 80°,
boils at 163° to 165° (16 mm.), and dissolves readily in water,

alcohol and chloroform ; it is levorotatory. It is completely con-

verted into carvacrol by boiling with dilute sulphuric acid. Its
oxime melts at 163°, its semicarbazone at 184° to 185°, and its
phenylhydrazone at 150° to 160°.

On reduction with alcohol and sodium, the keto-terpine gives
rise to a 1: 2: 8-trioryterpane, C,,H,,O,, which, when distilled under
diminished pressure and recrystallized from ether, forms plates,
melting at 97° to 98°; it is soluble in water and alcohol, and is
levorotatory. When this trioxyterpane is oxidized with chromic
anhydride and sulphuric acid, it yields an optically active methyl
ketone of homoterpenylic acid (a keto-lactone), C,,H,,O,, melting at
48° to 49°. (Compare with the keto-lactone obtained from ter-
pineol.)

1Baeyer, Ber., 28, 641.

2Baeyer, Ber., 28, 1589.

3Baeyer and Baumgirtel, Ber., 31, 3208.

222 THE TERPENES,

Oxidation of Carone.'

When carone is oxidized with an alkaline solution of potassium
permanganate, it yields oxalic acid and another acid which is cap-
able of existing in cis- and trans-modifications ; the latter acid is
termed caronic acid or gem-dimethyltrimethylene-1 : 2-dicarboxylic
acid. (The prefix gem is employed by Baeyer for compounds
containing two alkyl groups attached to the same carbon atom.)

The caronic acids,
CH, De

on, \ba—coon

are formed by heating carone with potassium permanganate in a
. reflux apparatus on the water-bath, for thirty-six hours ; after the
removal of the oxalic acid, the neutral liquid is extracted with
ether, rendered acid, and again extracted with ether, the acid
syrup thus obtained depositing the cis-acid in crystals, while the
trans-acid is separated by conversion into its ammonium salt.

Cis-caronic acid, C,H,,O,, crystallizes from water in plates, and
melts at 174° to 175°; it is soluble in chloroform, but dissolves
sparingly in ether and petroleum. It forms a crystalline ammonium
salt. Its anhydride is produced by melting the acid, and separates
from ether in crystals, melting at 54° to 56°. When the acid is
heated with a solution of hydrobromic acid, it is converted into
the isomeric terebic acid.

Trans-caronic acid, C_H,,O,, crystallizes from water in prisms,
and melts at 212°. It does not yield an anhydride, but may be
converted into terebic acid in the same manner as the cis-modifi-
cation.

Caronic acid has also been synthetically prepared by Perkin
and Thorpe in such a manner as to confirm the above constitu-
tional formula which Baeyer assigned to it.

According to Baeyer, carone has the constitution represented
by the formula,

CH, H—CO—CH—CH,
>C
CH, \CH—CH,—CH,

Baeyer regards it as probable that carone differs from eucar-
vone merely by the presence of a double linkage in the latter
compound.

1Baeyer and Ipatieff, Ber., 29,2796; Baeyer and Villiger, Ber., 31, 1401;

Perkin and Thorpe, Proc. Chem. Soc., 1898, 107; Baeyer and Villiger, Ber.,.

$1, 2067.

OO

ae

So Op te

ee ee

Oh oie

NITROSODIHYDROEUCARVONE. 223

5. DIHYDROEUCARVONE, ©,,H,,0.

Dihydroeucarvone is formed when dihydroeucarveol is oxidized
with Beckmann’s chromic acid mixture. It boils at 86° to 88°
under 14 mm. pressure, and, like eucarvone, has a faint odor of
peppermint and of camphor (Baeyer'). It is unstable towards
permanganate, and yields an oily oxime, which forms a very
characteristic, crystalline hydriodide.

Dihydroeucarvoxime hydriodide, C,,H,,I. NOH, is prepared when
dihydroeucarvoxime is allowed to remain in a glacial acetic acid
solution of hydriodic acid for twelve hours. It is obtained in
splendid, colorless prisms, melts at 161°, and is only slightly
soluble in the ordinary solvents. When it is reduced with alcohol
and sodium, it yields dihydroeucarvylamine, C,,H,,NH,; but on
reduction with zinc dust and alcoholic hydrochloric acid, it is con-
verted into tetrahydroeucarvone,’ C,,H,,O.

Dihydroeucarvone semicarbazone, C,,H,,—N-NH-CO-NH,, crys-
tallizes in thin plates; it is readily soluble in alcohol, and melts
at 189° to 191°.

Nitrosodihydroeucarvone, C,,H,,ONO, is prepared by adding

ten drops of hydrochloric acid to a mixture of seven grams of di-
hydroeucarvone and five grams of amyl nitrite, which is well
cooled by a freezing mixture; three hours should be required for
the addition of the hydrochloric acid.* It forms large, colorless
prisms, melts and decomposes at 121° to 124°, and is very char-
acteristic of dihydroeucarvone. Baeyer regards it as a bisnitroso-
derivative, (C,,H,,O),N,O,.
_ According to Baeyer,? dihydroeucarvone is a methyl-gem-di-
methyleycloheptenone, and, when oxidized with a saturated solu-
tion of potassium permanganate, it gives rise to unsymmetrical or
gem-dimethylsuccinic acid. Baeyer regards this as evidence of the
presence of the gem-dimethyl group in the molecule of dihydroeu-
carvone, as well as in that of eucarvone.

Dihydroeucarvone yields dihydroeucarveol when it is reduced
with alcohol and sodium.

On treating dihydroeucarvone with phosphorus pentachloride,
a chloride, C,,H,,Cl, is formed, which boils at 92° to 93° under
18 mm. pressure, and has a sp. gr. 1.02 and refractive index,
ny, = 1.51250, at 18°.

1Baeyer, Ber., 27, 1922.
2Baeyer and Villiger, Ber., 37, 2067.
3Baeyer, Ber., 27, 1923; 2% 646.

224 THE TERPENES.

6. DIHYDROEUCARVEOL, C,,H,,OH.

Dihydroeucarveol is formed when eucarvone, C,,H,,O, or dihy-
droeucarvone, C,,H,,O, is reduced in an alcoholic solution with
sodium ; during the reaction the solution changes in color from a
deep bluish-violet to red, and eventually becomes colorless. It
was discovered by Baeyer.'

It is a colorless, thick oil, which has a camphor-like odor, and
boils at 109° to 110° under a pressure of 21 mm. It is an un-
saturated alcohol, and, when oxidized with chromic anhydride,
yields dihydroeucarvone.

Dihydroeucarvyl acetate,? C,,H,,O:-COCH,, boils at 223° to
224°, and hasa sp. gr. 0.951 and a refractive index, np = 1.46315,
at 20°.

Dihydroeucarvyl chloride,’ C,,H,,Cl, boils at 85° under 20 mm.
pressure. It does not form 2-chlorocymene, but may be converted
into Baeyer’s euterpene.

When 100 grams of dihydroeucarveol are treated with 200
grams of phosphorus pentachloride, and the resulting chloride is
boiled with quinoline during half an hour, a hydrocarbon, euter-
pene,’ C,,H,,, is produced ; this terpene boils at 161° to 165°, and
yields acetic, oxalic and gem-dimethylsuccinic acids on oxidation
with permanganate. F==— jvs..

7. THUJONE (TANACETONE), C,,H,,0.

The investigations of Schweizer* and of Jahns*® determined
that thuja oil contains a ketone, C,,H,,O. Wallach ® has more re-
cently examined thuja oil and found, as has already been indicated,
that it consists principally of levorotatory fenchone and another
ketone, C,,H,,O, for which he proposed the name thujone. The
same name had been used by Jahns to designate the ketone which
he obtained from thuja oil.

Simultaneous with Wallach’s investigations, Semmler’ was en-
gaged in researches on the oil of tansy (Tanacetum vulgare), and
he showed that it contains a compound which he identified as a
ketone ; the same substance had previously been discovered by

1Baeyer, Ber., 27, 1922.

2Klages and Kraith, Ber., 32, 2550.
3Baeyer and Villiger, Ber., 31, 2067.
4Schweizer, Ann. Chem., 52, 398.
5Jahns, Arch. Pharm. (1883), 221, 748.
§Wallach, Ann. Chem., 272, 109.
7Semmler, Ber., 25, 3343.

fe

ea Ne ree. ~-

THUJONE. 225

Bruylants,’ and described as an aldehyde under the name of tan-
acetone. Semmler found tanacetone to be identical with absinthol,
which is the name given by Beilstein and Kupfer? to a constituent
of the oil of absinth ; he also regarded it as identical with salviol,

_ a compound found by Muir and Sigiura* in the oil of sage. In

his first publication, Semmler considered the thujone obtained by
Jahus and Wallach as identical with tanacetone.

This view has been strengthened by Wallach’s * subsequent in-
vestigations of thujone, and seems to be proved by the prepara-
tion of many derivatives of both compounds. Nevertheless, the
behavior of tanacetone and thujone does not perfectly agree in all
respects, and, therefore, Semmler® has denied the identity of tan-
acetone and thujone. However, there can be no doubt as to the
chemical identity of these compounds, for Wallach* has proved
that the same ketone may be separated from all of the above-
mentioned oils by means of its acid sodium sulphite compound,
and that the differences, which have been observed in the be-
havior of thujone and tanacetone, may be attributed to admix-
tures of foreign substances with the crude ketone.

It is also worthy of notice that experiments conducted in the
laboratories of Schimmel & Co. have indicated that thujone occurs
in specially large quantities in the ethereal oil of Artemisia barrelieri.

PREPARATION.—Thujone is contained in a comparatively pure

- condition in artemisia oil, and also in the more accessible oil of

tansy. Two hundred grams of the latter oil are shaken with a
mixture of two hundred ce. of a saturated solution of acid sodium
sulphite, seventy-five cc. of water and three hundred ce. of alcohol ;
no further separation of crystals takes place after standing for
about two weeks. The mixture is then well cooled, the crystals
are filtered with the pump, washed with alcohol and ether, and
decomposed with soda; pure thujone is obtained in a quantity
equal to forty-seven per cent. of the crude oil. This product con-
tains, as impurities, small quantities of substances having an alde-
hydic character; the latter are removed by heating with an am-
moniacal silver solution (Semmler).

The other above-mentioned oils contain thujone in such small
amounts that the acid sodium sulphite compound is obtained as a
solid product only with difficulty; thujone is contained in the

1Bruylants, Ber., 11, 450.

2Beilstein and Kupfer, Ann. Chem., 170, 290.
3Muir and Sigiura, Jahresb. Chem., 1879, 980.
4Wallach, Ann. Chem., 275, 179; 279, 383.
5Semmler, Ber., 27, 897.

6Wallach, Ann. Chem., 286, 90.

15

226 THE TERPENES.

fractions of these oils boiling at 80° to 90° under a pressure of
14 mm., or at 195° to 200° under ordinary pressure.

PROPERTIES.—Pure thujone is an optically active oil, which
boils at 84.5° under 13 mm. pressure, or at 203° under the ordi-
nary pressure ; it has a specific gravity of 0.9126 and refractive.
power, ny = 1.4495, at 20° (Semmler’). Wallach? found similar
constants. According to Semmler,® pure thujone has a specific
rotatory power of about 68°; the rotatory power is diminished,
and the capacity of the ketone to unite with acid sodium sulphite
is lessened, by the continued boiling of thujone.

It is converted into the isomeride, carvotanacetone, by heating
to high temperatures (Semmler). Isothujone is produced when
thujone is boiled with dilute sulphuric acid. When thujone is
heated with ferric chloride, it readily yields carvacrol ; this is also
formed as a by-product in the preparation of carvotanacetone from
_ thujone (Wallach’).

Different opinions are held as to whether thujone should be
regarded as an unsaturated compound. The molecular refraction
indicates the presence of a diagonal linkage, whilst its extreme
sensitiveness towards permanganate points against this assumption.
Thujone behaves as a saturated compound towards bromine; it
combines slowly with this element forming a substitution product,
which Wallach regards as very characteristic.

Thujone tribromide, C,,H,,OBr,, is prepared when five cc. of
bromine are added in one portion toa solution of five grams of
thujone in thirty cc. of petroleum ether, contained ina rather large
beaker. An energetic reaction takes place, accompanied by a
violent evolution of hydrogen bromide. When the petroleum
ether is allowed to evaporate slowly, a crystalline mass is generally
obtained ; in case the reaction-product does not solidify at once,
a little more petroleum ether and bromine are added. The product
is pressed on a porous plate, and crystallized from ethyl acetate. It
forms large, well defined, monoclinic prisms, is very sparingly solu-
ble in cold alcohol, melts and decomposes at 121° to 122°( Wallach’).

When thujone tribromide is treated with a solution of sodium
in'methy] alcohol, one molecule of hydrogen bromide is eliminated,
and one atom of bromine is replaced by a methoxyl-group, form-
ing a compound which is phenolic in character (Wallach) :

C,,H,,OBr, + 2NaOCH, = 2NaBr + CH,OH + C,,H,,Br(OH)(OCH,).

1Semmler, Ber., 25, 3343.

2Wallach, Ber., 28, 1955.

3Semmler, Ber., 27, 897.

4Wallach, Ann. Chem., 275, 197; 286, 109; see Semmler, Ber., 33, 2454.
5Wallach, Ann. Chem., 275, 197; 286, 129.

THUJONOXIME. 227

This intramolecular change is analogous to the transposition of
carvone into carvacrol, and may be graphically represented by the
following formulas :

Hy Hs;
'H. ‘
B O Br OH
Da
B 'H, CH,O ya
Br
3H, sH,
Thujone tribromide. Methoxy-bromocarvacrol.

This phenol separates from methy] alcohol in colorless erystals,
and melts at 156° to 157° ; it forms an acetyl compound, melting
at 63° to 64°, and a methy] ether, melting at 42° to 43° (Wallach).

The action of sodium and ethyl alcohol converts thujone tri-
bromide into an ethowyl-compound, C,,H,,Br(OH)(OC,H,), melt-
ing at.144° to 145°. When thujone tribromide is boiled with
sodium acetate and glacial acetic acid, an acetyl compound is ob-
tained, which yields a quinone by hydrolysis with ferric chloride.
A more detailed examination of this quinone has not been made,
but its formation indicates that the methoxyl-group of the phenol
stands in the para-position to the hydroxyl-group.

Thujyl alcohol, C,,H,,OH, is formed when thujone is reduced
with sodium and alcohol.

An amine, C,,H,,NH,, results by the treatment of thujone with
ammonium formate ; the same base is also obtained by the reduc-
tion of thujonoxime with sodium and alcohol, and has been described
by Semmler as tanacetylamine, and by Wallach as thujylamine.

Thujolacetic acid,’ C,,H,,(OH)-CH,:-COOH, is produced by the
action of zine on a mixture of thujone and bromoacetic acid ; it
crystallizes from a mixture of benzene and petroleum in leaflets,
and melts at 90° to 91°. The ethyl ester, prepared from thujone
and ethyl bromoacetate, boils at 154° to 164° (14 mm.).

Thujonoxime, C,,H,,NOH, boils at 135° to 136° under a pres-
sure of 20 mm., and solidifies in long prisms, which melt at 51.5°
(Semmler). The oxime prepared from impure thujone is repre-
sented by Wallach as an oil, and the fact that Semmler was never

_ able to obtain this oxime as a solid compound formed an impor-

tant argument for his assumption that thujone and tanacetone are

1Wallach, Ann. Chem, 275, 197; 286, 109.
2Wallach, Ann. Chem., 314, 147.

228 THE TERPENES.

not identical. Wallach,’ however, has found that thujonoxime
may always be obtained as a solid, if the thujone be previously
purified by means of its acid sodium sulphite compound.

Thujonoxime melts at 54° to 55°, and may be converted into
an isomeric oxime by treatment of its chloroform solution with
phosphorus pentachloride. This isomeride is sparingly soluble,
crystallizes in monoclinic prisms, and melts at 90° ; it is not vol-
atile with steam, and its alcoholic solution is feebly dextrorota-
tory (Wallach ’).

When thujonoxime is dissolved in concentrated sulphuric acid
and the temperature maintained below 50° to 60°, it is converted
into optically inactive isothujonoxime, which is volatile with
steam, and melts at 119° to 120° (Wallach ’).

Phosphorus pentoxide converts thujonoxime into a nitrile, to-
gether with carvacrylamine ; the properties of the nitrile are not
described by Wallach.

Thujonoxime yields carvacrylamine on heating with alcoholic
sulphuric acid (Semmler*); the same amine is also obtained in a
similar manner from carvoxime (see page 190).

JH;

sH,
Carvacrylamine.

Thujone semicarbazone, C,,H,,—N-NH-CO-NH,, forms acute
prisms, and melts at 171° to 172° (Baeyer’).

According to Rimini,‘ thujonoxime, on treatment with amyl
nitrite, yields crystals of thujylimine nitrate. By the action of
nitrous acid, it gives rise to a pernitroso-derivative, which decom-
poses on heating, and, when distilled with steam in presence of
potash, yields thujone and nitrous oxide; with hydroxylamine,
thujonoxime is regenerated. When the pernitroso-compound is
treated with an alcoholic solution of the calculated quantities of
semicarbazide hydrochloride and sodium acetate, thujone semicar- —

1Wallach, Ann. Chem., 277, 159; 286, 94.
2Semmler, Ber., 25, 3352.

3Baeyer, Ber., 27, 1923.

4H. Rimini, Gazz. Chim., 30 [I], 600.

LF

B-THUJAKETONIC ACID, 229

bazone is formed; it separates in needles, melting at 178°.
Rimini gives the same melting point, 178°, for the semicarbazone
which is prepared directly from thujone.

Oxymethylene thujone, C,,H,,O = CHOH, is obtained when an
ethereal solution of pure thujone is treated with sodium and amyl
formate. It is purified by distillation with steam, melts at 40°,
and boils at 115° to 118° under a pressure of 16 mm. It gives
an intensive reaction with ferric chloride, and decomposes easily
when allowed to stand in the air (Wallach’).

The behavior of thujone and tanacetone towards potassium per-
manganate and towards bromine and sodium hydroxide has been
carefully studied by Wallach? and by Semmler*; the fact that
the same very characteristic acids were obtained during the inves-
tigations of both compounds supports the view that thujone and
tanacetone are identical.

a- and -Thujaketonic acids (tanacetoketocarboxylic acids),

COCH,
CH
COOH

are produced when pure thujone or the fraction of thuja oil boil-
ing between 190° and 200° (compare with the preparation of
levorotatory fenchone, see page 157) is agitated with permanganate
solution at a medium temperature; the quantity of potassium
permanganate employed is so regulated that two atoms of oxygen
may act on one molecule of thujone. When the oxidation is
complete, the unchanged oil is distilled off with steam, the residue
is filtered, and the resultant acids are separated from the filtrate
by the usual method. According to the conditions under which
the oxidation is performed, more or less of one of the two isomeric
acids is obtained.

a-Thujaketonic acid,* C,,H,,O,, crystallizes from water in well
defined, transparent, brittle plates, and melts at 75° to 76°; it
is soluble in about forty parts of boiling water, and does not
crystallize at once on cooling, but only after long standing.
Alkaline hypobromite converts it into a-tanacetogendicarborylic
acid, C,H,,O,, which melts at 141° to 142°.

$-Thujaketonic acid * (3-metho-ethyl-2-heptene-6-onoic acid), C,,-
H,,0,, is produced generally in larger quantities than the a-acid ;

16 ~ 3?

1Wallach, Ber., 28, 33.

2Wallach, Ann. Chem., 272, 111; 275, 164.

3Semmler, Ber., 25, 3346 and 3513.

4Wallach, Ber., 30, 423; Tiemann and Semmler, Ber., 30, 429.

230 » THE TERPENES.

it is also formed by heating an aqueous solution of the a-acid for
some time, and is rapidly formed when the a-acid is heated at 150°
under reduced pressure. It is soluble in seventy parts of boiling
water, and crystallizes at once on cooling; it forms small, fine
needles, melting at 78° to 79°.

Both thujaketonic acids form silver salts, C,,H,,O,Ag, which are
sparingly soluble in water.

The liberation of iodoform or bromoform by the treatment of
both acids with iodine or bromine and sodium hydroxide, and the
formation of a ketone, C,H,,O, by the dry distillation of these
acids, indicate that they are to be regarded as ketonic acids, and
that they contain the group, CO-CH,. Wallach regards the
f-acid as unsaturated, but the a-acid is saturated, and is so con-
structed as to form an ethylene linkage under the influence of
acids and high temperature.

f-Tanacetogendicarboxylic acid (3-metho-ethyl-2-hexene-dioic
acid), C,H,,O,, results by the action of alkaline hypobromite on
$-thujaketonic (f-tanacetoketonic) acid ; it crystallizes from water,
and melts at 116° to 118° (Tiemann and Semmler), or at 113° to
114° (Wallach).

a-Tanacetogendicarboxylic acid, C,H, ,O,, is formed by the action
of sodium hydroxide and bromine on a-thujaketonic (a-tanaceto-
ketonic) acid, bromoform being eliminated. It is a dibasic acid,
melts at 141° to 142°, and may be readily converted into an
anhydride, C,H,,O,, when it is heated with acetic anhydride ; the
anhydride crystallizes in white needles, melts at 55°, and boils at
171.5° under 16 mm. pressure.

_ When a-tanacetogendicarboxylic acid is fused with potash, it
readily yields pimelic acid,

COOH H

whilst by the distillation with soda-lime it is changed into tana-
cetophorone, C,H,,O. The latter compound is an oil, having an
odor similar to that of camphorone; it boils at 89° to 90° under
a pressure of 13 mm., has a specific gravity 0.9378 and a refrac-
tive power, np, = 1.4817, at 20°. By the oxidation of tanaceto-
phorone with potassium permanganate, a solid lactone, C,H,,O,,
is produced, which boils at 145° under 11 mm. (Semmler).
w-Dimethyl laevulinic methyl (isobutyryl ethyl methyl) ketone,
or 2-methylheptone-3 : 6-dione, C,H,,O,, is formed by the oxidation
of £-thujaketonic acid in an alkaline solution with a two per cent.
solution of potassium permanganate ; it boils at 102° to 106° at

ay a ns EP

eee

METHYL HEPTYLENE KETONE. 231

23 mm., has the specific gravity 0.9402 at 20°, and the refractive
index, Ny, = 1.4321; the molecular refraction is M= 39.47. Its
oxime separates from water in prisms, and melts at 132°.
w-Dimethyl laevulinic (3-methyl hexan-3-onoic) acid, C,H,,O,, is

formed by treating the preceding diketone with alkaline ‘hypobro-
mite, bromoform being eliminated ; it melts at 32°, and boils at
145° to 146° under a pressure of 20 mm. This acid also results
on the oxidation of f-tanacetogendicarboxylic acid with potassium
permanganate. It yields a sparingly soluble silver salt, and an
oxime,’ melting at 88° to 89°. This acid is identical with 0-di-
methyl] laevulinic acid prepared by Fittig and Silberstein.’

2-Methyl-5-isopropylpyrroline, C,H,,NH, is produced by heat-
ing the diketone, C,H, Oz, with alcoholic ammonia in sealed tubes
at 180°, for two hours ; it has the specific gravity 0.9051 at 20°,
the refractive index, np = 1.4988, and the molecular refraction,
M = 39.86.

a- and §-Thujaketoximic acids (tanacetoketoximic acids),

C(NOH)—CH,
OOH

C,H,

are prepared by the action of a warm, concentrated solution of
one part of hydroxylamine hydrochloride on one part of the
ketonic acid dissolved in one part of potassium hydroxide. The
a-ketoximic acid melts and decomposes at 168°, the f-acid melts
at 104° to 106°. The formation of these acids indicates that the
a- and f-thujaketonic acids contain a ketone group. The a-ke-
toximic acid yields a hydrochloride, C,,H,,O,,NOH-HCl, melting
at 128° to 129°, and a hydrobromide, C, H, 0, -NOH. HBr, which
melts at 176° to 177°.

Methyl heptylene ketone, C,H,,-CO-CH,, is obtained when /-
thujaketonic acid is submitted to dry distillation. It is also formed
by a similar process from the a-ketonic acid, which is at first con-
verted into the f-acid during the distillation.

Tt boils at 184° to 186°, has the specific gravity 0.854 at 20°,
and the refractive index, n, = 1.44104; it combines directly
with bromine, forming additive products. It is converted into
dihydropseudocumene, OC,H,,, when heated with zinc chloride
(Wallach). It forms a semicarbazone,* which melts at 143°. Its
benzylidene derivative,’ C,H,,O = CH-C,H,, crystallizes in white
needles, and melts at 170°,

1Tiemann and Semmler, Ber., 31, 2311.

2*Fittig and Silberstein, Ann. Chem., 283, 269; Fittig and Wolff, Ann.

Chem., 288, 176.
3Wallach, Ber., 30, 423.

232 THE TERPENES.

Tiemann and Semmler’ describe a compound, C,H,,O, under
the name tanacetoketone (thujaketone, or 2-methyl-3-metheneheptane-
6-one) ; they obtain it by the elimination of carbon dioxide from
8-tanacetoketonic (thujaketonic) acid, and represent its constitu-
tion by the formula,

; CH, = C( C,H) — CH, —_ CH, a= CO —CH;.

It is probably identical with Wallach’s methyl heptylene ketone.

Thujaketoxime (methyl heptylene ketoxime),’? C,H,,NOH, is
derived from methyl heptylene ketone, and boils at 118° to 120°
under 15 mm. On reduction, it yields a base, C,H,,NH,, which
boils at 78° to 79° (26 mm.), and forms a carbamide, melting at
104° to 105°. Phosphoric oxide acts vigorously on the oxime,
giving rise to the base, C,H,,NH,, which boils at 180° to 183°,
and has a specific gravity 0.892 at 25°; its picrate decomposes
above 170° without melting, and its platinochloride melts and de-
composes at 179°.

When methyl heptylene ketone is reduced with sodium and
alcohol, it yields an unsaturated alcohol, C,H,,.CH(OH)-CH,,
boiling at 185° to 187° ; it has an odor recalling that of linalool ;
its specific gravity is 0.848 and specific refractive power, np =
1.4458, at 21°. If this alcohol be heated with zinc chloride, or
better with dilute sulphuric acid (one part of sulphuric acid and
three parts of water), it yields an isomeric, saturated oxide, C,H,,O,
which boils at 149° to 151°, hence considerably lower than the
alcohol from which it is derived. This oxide has the specific
gravity 0.847 and the index of refraction, np = 1.42693, at 20°.

Thus, methyl heptylene ketone reacts like a homologue of
methyl hexylene ketone, which is formed by the dry distillation
of cineolic anhydride. The constitutional formulas of methyl
heptylene ketone and its above-mentioned derivatives are (Wal-
lach):

CH
cu, CH-C(CH:) =CH—CH,—CO—CH,
Methyl heptylene ketone.
Sin
cu, CH C( CH) =CH—CH,—CH (OH) —CH,
Methyl heptylene carbinol.
oS CH.C(CH,)—CH,—CH,—CH—C
CH,/ ~ 7 ao O - ARy —CH;
Dimethyl isopropyl butylene oxide.

1Tiemann and Semmler, Ber., 30, 429.
2Wallach, Ann. Chem., 309, 1.

a

TANACETOGEN DIOXIDE, 233

Tiemann and Semmler’ regard them as having a somewhat
different constitution.

According to Wallach,’ when the alcohol, C,H,,OH, obtained
by the reduction of methyl heptylene ketone, is oxidized with
potassium permanganate, a glycerol, C,H,(OH),, is produced ; it
is a syrupy liquid, and boils at 160° to 165° under 10 mm.
pressure. Hot, dilute sulphuric acid converts the glycerol into an
oxide, C,H,,0, which has an odor recalling that of pinole, and
boils at 160° to 165° ; its bromine. derivative, C,H,,BrO, erystal-
lizes from alcohol in white needles, and melts at 124.5°.

According to Tiemann and Semmler,*® when tanacetoketone
(thujaketone or methyl heptylene ketone) is oxidized with potas-
sium permanganate, it yields a small quantity of 0-(w)-dimethyl
laevulinic methyl ketone ; the chief product, however, is the keto-
glycol, 2-methyl-3-methyl-ol-heptan-6-one-3-ol, C,H, ,O(OH),.

Tanacetogen dioxide, C,H,,O,, results on distilling the keto-
glycol under reduced pressure, water being eliminated. It boils
at 72° to 75° (19 mm.), has the specific gravity 0.9775 at 20°,
the refractive index, n, = 1.4450, and the molecular refraction,
M = 42.50; it has an odor resembling that of menthol (Tiemann
and Semmler).

Oxidation of Thujone with Alkaline Hypobromite.

Varying results are obtained according to the different condi-
tions under which the oxidation may take place. Wallach first
observed, and was later confirmed by Semmler, that an acid,
C,,H,,O,, isomeric with camphoric acid, is obtained when the fol-

_ lowing method is employed.

Thirty grams of thujone are allowed to stand for two weeks
with a solution of seventy grams of bromine in 1250 ce. of a four
per cent. solution of sodium hydroxide. Any unchanged oil is
then removed by shaking with ether, the aqueous solution is con-
eentrated and acidified with dilute sulphuric acid; the acid,
C,,H,,O,, is thus precipitated in brilliant, crystalline leaflets. It
is recrystallized from water or dilute alcohol, and is obtained in
orthorhombic crystals, melting at 146° to 147°; it is saturated,
and is apparently a dibasic acid.

According to Semmler, if sixty parts of thujone (tanacetone)
are treated with a solution of 186 parts of bromine in 2,500 parts
of a four per cent. solution of sodium hydroxide, bromoform is

1Tiemann and Semmler, Ber., 28, 2136.
2Wallach, Ber., 30, 423.
3Tiemann and Semmler, Ber., 30, 429.

234 THE TERPENES.

liberated and tanacetogenic acid, C,H,,COOH, is formed. This
acid is an oil, which boils at 113.5° under a pressure of 15 mm.,
and solidifies when placed in a freezing mixture; it behaves as a
saturated compound.

The investigations respecting thujone are by no means com-
plete. While Wallach is inclined to regard it as an unsaturated
ketone related to dihydrocarvone, Semmler ' considers it as having
a diagonal linkage, and proposes the following formula:

H,
ze
hs

HG co
Bb Noe

H

OsH,
Thujone.

Wallach’? gives numerous reasons for not accepting this con-
stitutional formula.
Semmler* has more recently proposed the following formula

for thujone :
H
a #
H, | 2
se
eae

8. THUJYL ALCOHOL (TANACETYL ALCOHOL), C,,H,,.OH.

Thujone is quantitatively changed into thujyl alcohol, when
twenty-four parts of thujone are dissolved in 100 parts of alcohol
and reduced by the gradual addition of eighteen parts of sodium ;
sufficient alcohol is subsequently added to dissolve all of the
sodium. Thujyl alcohol boils at 92.5° under 13 mm. pressure,
has a sp. gr. 0.9249 and index of refraction, np = 1.4635, at
20°. It behaves as a saturated compound (Semmler *).

1Semmler, Ber., 27, 898.

2Wallach, Ann. Chem., 286, 116.

3Semmler, Ber., 33, 275 and 2454.

4Semmler, Ber., 25, 3344; compare Wallach, Ann. Chem., 272, 109.

ISOTHUJONOXIME. 235

An impure alcohol, obtained from thujone by Wallach, boiled at
210° to 212°, and had the sp. gr. of 0.9265 at 20°.

Thujyl chloride (tanacetyl chloride), C,,H,,Cl, results by treating
thujyl alcohol with phosphorus pentachloride, petroleum ether
being used as a diluent. It is an oil, boiling at 72° under 10
mm. pressure. It is very stable, and can not be converted into a
terpene, C,,H,,, by boiling with aniline and alcohol. It will be
recalled, however, that such a terpene, thujene, may be prepared
indirectly from thujone by the dry distillation of thujylamine
hydrochloride.

9, ISOTHUJONE, C,,H,,0.

Isothujone is obtained by boiling twenty-five grams of thu-
jone with seventy-five cc. of a mixture of one volume of concen-
trated sulphuric acid and two volumes of water for eight to ten
hours, in a reflux apparatus, the product being then distilled in a
current of steam (Wallach’ ).

Isothujone differs from thujone in its higher specific gravity
and higher boiling point. It boils at 231° to 232°, has the sp.
gr. 0.927 and the refractive index, ny = 1.48217 at 20°; it im-
mediately reduces a cold solution of potassium permanganate,
thus indicating that it is an unsaturated compound.

Isothujolacetic acid,’ C,,H,(OH)-CH,-COOH, melts at 168° to
170°.

Isothujonoxime, C,,H,,NOH, may be obtained by treating thu-
jonoxime (m. p. 54° to 55°) with concentrated sulphuric acid ac-
cording to the method given on page 228; it is, however, more

conveniently prepared from isothujone.

_ Twenty grams of hydroxylamine hydrochloride are covered
with fifty cc. of methyl alcohol, and the well cooled mixture is
treated with a solution of twenty grams of potassium hydrox-
ide in fifteen grams of water; the filtered solution is then
boiled with ten grams of isothujone for ten minutes. The
oxime is precipitated with water, and on recrystallization forms
long needles, melting at 119° ; it is sparingly soluble in petroleum
ether (Wallach ').

Isothujone yields two isomeric semicarbazones, which melt at
208° to 209°, and at 184° to 185°, respectively ; if they are
warmed with dilute sulphuric acid, isothujone is regenerated

( Wallach’).

1Wallach, Ann. Chem., 286, 101.
2Wallach, Ann. Chem., 314, 147.
8Wallach, Ber., 28, 1955.

236 THE TERPENES.

Dihydroisothujol or thujamenthol, C,,H,,OH, is formed by reduc-
ing isothujone with sodium and alcohol. It boils at 211° to
212°, has a sp. gr. of 0.9015 and index of refraction, np =
1.46306, at 20°; it is not identical with menthol or tetrahydro-
carveol (carvomenthol) (Wallach’*).

Thujamenthone, C,,H,,O, is obtained when dihydroisothujol is
oxidized in glacial acetic acid solution with chromic anhydride ;
it is isomeric, but not identical, with carvomenthone.

Isothujaketonic acid, C,,H,,O,, is produced by the oxidation of
isothujone with potassium permanganate ; it is a saturated acid,
and boils at 271° to 273° at ordinary pressure, and at 142° to
143° under a pressure of 12 mm. Its semicarbazone melts at
193°, and its oxime at 153°.

Sodium hypobromite converts isothujaketonic acid into iso-
propyl succinic acid and bromoform (Wallach’).

When isothujaketonic acid is distilled under atmospheric
pressure, it is converted into the keto-lactone, C,,H,,O,, which
melts at 43°; its ovime meltsat 155°. The same keto-lactone is
also formed on oxidizing thujamenthone with chromic acid. On
further oxidation, this keto-lactone yields f-isopropyl laevulinic
acid (Semmler’*).

10. CARVOTANACETONE, ©,,H,,0.

Pure thujone, when heated alone in a sealed tube at 280° for
twenty-four hours, is converted into an isomeric compound, car-
votanacetone, which has an intensive odor resembling that of car-
away, and a higher boiling point than that of thujone (Semmler ‘).
Wallach’s® experiments show that it is highly probable that
carvotanacetone is also contained in the high boiling fractions of
thuja oil. It may be surmised, therefore, that even during the
fractional distillation of thuja oil under ordinary pressure a por-
tion of the thujone is transformed into carvotanacetone ; a definite
conclusion, however, has not yet been reached.

In order to prepare pure carvotanacetone, heat thujone in a
sealed tube, as above suggested, and submit the product to a
fractional distillation, collecting the largest fraction at 220° to
225°. Convert this fraction into the oxime, and regenerate pure
carvotanacetone by heating the oxime with dilute sulphuric acid
(Semmler °).

1Wallach, Ann. Chem., 286, 101.
2Wallach, Ber., 30, 423.

3Semmler, Ber., 33, 275.

4Semmler, Ber., 27, 895.

5Wallach, Ann. Chem., 275, 183; 279, 385.
6Semmler, Ber., 27, 895; 33, 2454.

PULEGONE. 237

PROPERTIES.—Carvotanacetone is a liquid boiling at 228°, has
a specific gravity of 0.9373 and refractive power, np = 1.4835, at
17° (Semmler’). Wallach’ found similar constants. The spe-
cific gravity, refractive index and boiling point are, therefore, con-
siderably higher than those of thujone. Its odor is very like that
of carvone.

It is an unsaturated ketone, and combines with four atoms of
hydrogen forming an alcohol, C,,H,,OH, when it is reduced in an
alcoholic solution with sodium. Semmler regards this alcohol
as identical with oxy-2-hexahydro-p-cymene (tetrahydrocarveol),
which was prepared by Baeyer in the reduction of dihydrocar-
veol, and by Wallach by the reduction of carvenone. The results
of Wallach’s’ researches fully establish Semmler’s view.

Carvotanacetone unites with hydrogen sulphide in ammoniacal
solution ;* the product melts at about 95°.

Carvotanacetoxime, C,,H,,NOH, is obtained from crude carvo-
tanacetone, as already indicated; it crystallizes from methyl
alcohol, and melts at 92° to 93°. It is optically inactive (Wal-
lach ').

Wallach obtained an oxime having the same melting point (93°
to 94°) from the fraction of thuja oil, which boils at 220° to
230°.

Carvotanacetone semicarbazone forms orthorhombic tablets or
acute prisms, and melts at 177° (Baeyer *).

According to Harries, the oxaminoxime of carvotanacetone
sinters at 155° and melts at 162°; it was not obtained quite
pure, hence Harries * regards it as probable that carvotanacetone
is a mixture of the racemic form of dihydrocarvone with other
compounds.

When carvotanacetone is oxidized with a dilute solution of
potassium permanganate, it yields pyruvic and isopropylsuccinic
acids. From this fact Semmler’ concludes that carvotanacetone
is an ortho-terpene ketone, and that the pseudo-ketone corre-
sponding to it is found in terpenone,’ C,,H,,O (obtained from
tetrahydrocarvone).

11. PULEGONE, C,,H,,0.

The ethereal oils of Mentha pulegium and Hedeoma pulegioides
Persoon, which are sold under the name of pennyroyal oil, contain a

1Wallach, Ber., 28, 1955.

2Semmler, Ber., 27, 895; 33, 2454.

3Baeyer, Ber., 27, 1923; see Harries, Ber., 34, 1924.
4Harries, Ber., 34, 1924.

5Baeyer and Oehler, Ber., 29, 35.

238 THE TERPENES.

ketone, C,,H,,O, as their chief constituent ; this ketone was sub-
jected to a detailed investigation by Beckmann and Pleissner.’
The most valuable result of this research is the establishment
of the fact that pulegone may be converted into menthone by
the addition of hydrogen; all of the other ketones, which have
been mentioned up to this point, may be derived from carvo-
menthone.

Beckmann and Pleissner isolated pulegone from Spanish oil of
pennyroyal by the fractional distillation of this oil under dimin-
ished pressure. They found that on fractionating the oil under
atmospheric pressure some decomposition always takes place with
formation of a dark yellow oil; the specific rotatory power of the
original oil is also diminished. Nearly all of the oil of penny-
royal distills at 130° to 131° under a pressure of 60 mm.; this
fraction consists of pure pulegone.

Pulegone’ is dextrorotatory, [a])= + 22.89°; its specific
gravity is 0.9323 and refractive index, ny = 1.47018, at 20°. It
quickly turns yellow, even when kept in closed vessels; it is a
rather thick liquid, does not solidify when cooled to —20°, and
has an odor recalling that of peppermint.

Wallach? gives the following properties of pulegone regenerated
from its acid sodium sulphite compound.

Boiling point, 221° to 222°; specific gravity, 0.936; refrac-
tive index, n, = 1.4868.

Pulegone does not combine with hydrogen sulphide ; it imparts
an intense violet color to a fuchsine-sulphurous acid solution, and
reduces an ammoniacal silver nitrate solution after continued
boiling.

Although Beckmann and_ Pleissner did not obtain a compound
of pulegone with acid sodium sulphite, Baeyer and Henrich? pre-
pared such a derivative by allowing 100 cc. of pulegone to stand
for a long time with 210 cc. of acid sodium sulphite solution and
fifty ec. to sixty cc. of aleohol. The properties of pulegone re-
generated from its bisulphite compound by means of potash agree
completely with those of the product obtained by the vacuum
distillation of oil of pennyroyal.

Pulegone hydrochloride, C,,H,,O - HCl, is produced by the treat-
ment of pure pulegone with a solution of hydrochloric acid in
glacial acetic acid. It is crystallized from ligroine, forming large

1 Beckmann and Pleissner, Ann. Chem., 262, 1; compare Kane, Ann. Chem.,
82, 286 (1839); Butlerow, Jahresb. Chem., 1854, 595; Kremer’s Ana-
lysis of the volatile oil of Hedeoma pulegoides, Cincinnati, 1887.

2Wallach, Ber., 28, 1955.

S’Baeyer and Henrich, Ber., 28, 652.

HYDROBROMOPULEGONOXIME, 239

crystals, which are often one centimeter in length and melt at
24° to 25°. Pulegone is regenerated when the hydrochloride is
warmed with methyl! alcoholic potash (Baeyer and Henrich’).

Pulegone hydrobromide, C,,H,,O- HBr, is prepared when dry
hydrobromic acid is passed into a well cooled solution of pule-
gone in petroleum ether. On evaporation of the solvent, it is de-
posited in small, brilliant, colorless crystals, which are filtered and
washed with fifty per cent. alcohol. For further purification, its
ethereal solution is shaken with cold, dilute sodium hydroxide,
the ether is evaporated, and the residue crystallized from dilute
alcohol. It separates in hard, colorless crystals, melting at 40.5°.
It is optically levorotatory, [a], = — 33.88°; it gradually de-
composes on keeping, forming a dark colored, viscous oil. When
dissolved in ether, it is converted into pulegone by freshly pre-
cipitated silver oxide. Pulegone and another compound (inactive
pulegone?) are formed by boiling an ethereal solution of the hy-
drobromide with lead hydroxide (Beckmann and Pleissner).
When pulegone hydrobromide is boiled with alcohol and lead hy-
droxide, the chief product is methyl cyclohexanone, C,H,,O
(Harries ’).

Hydrobromopulegonoxime, C,,H,,Br- NOH, melts at 38°, and
readily loses hydrogen bromide ; in the presence of water hydro-
bromic acid is eliminated, and the compound is converted into the
“ hydrated pulegonoxime ” described below.

When pulegone hydrobromide is reduced with zinc dust in
an alcoholic solution, it yields a ketone, C,,H,,O, which pos-
sesses all the properties of levorotatory menthone, except that
it yields an oxime, melting at 84° to 85°, while levorotatory
menthonoxime melts at 59°. The close relation of this ketone to

‘levo-menthone is shown by the fact that when it is reduced

with sodium in an ethereal solution, according to Beckmann’s*
method, it yields levo-menthol, whose benzoyl derivative may
be isolated and characterized by its melting point and specific
rotatory power.

The close relation of pulegone to menthone was proved by the
observations of Beckmann and Pleissner in a much simpler manner
than by the above-suggested transformation. When pulegone is
reduced in an ethereal solution with sodium, levo-menthol is
formed. If the treatment of pulegone with sodium be repeated
three times, solid menthol is obtained, which can be identified

1Baeyer and Henrich, Ber., 28, 652.
Harries and Roeder, Ber., 32, 3357.
sBeckmann, German patent, No. 42458; Ber., 22, 912.

240 THE TERPENES, .

not only by its melting point and the preparation of its benzoyl
ester, but also by its transformation into levorotatory menthone
and the oxime of the latter. on

Pulegonoxime, C,,H,,NOH.—Although Beckmann and Pleiss-
ner obtained only the “‘ hydrated oxime” from pulegone, Barbier’
has described a normal pulegonoxime, C,,H,,NOH, as an oil,
whieh boils at 170° under 48 mm. pressure. Wallach? found
that normal pulegonoxime can be obtained as a solid, if it be pre-
pared according to the method described in the preparation of
carvoxime, and the product be distilled in a current of steam.
The volatile, solid oxime is pressed on a plate, and crystallized
from ether or petroleum ether; it crystallizes in transparent
prisms, and melts at 118° to 119°.

The pulegone regenerated by treatment of this oxime with
dilute sulphuric acid seems to be impure, since it boils at 220° to
225°; nevertheless, it yields the oxime, melting at 118° to 119°,
by the action of hydroxylamine.

Pulegylamine, C,,H,,NH,, results by reducing an alcoholic solu-
tion of pulegonoxime with sodium (Wallach *).

BECKMANN AND PLEISSNER’S “HYDRATED PULEGON-
OXIME,” C,,H,,NO,, AND ITS DERIVATIVES.

An oxime of pulegone, differing from the normal pulegonoxime
by containing one molecule of water, was obtained by Beckmann
and Pleissner as follows. Twenty parts of pulegone, ten parts of
ninety per cent. alcohol, thirty parts of ether and twelve parts of
hydroxylamine hydrochloride are heated in a reflux apparatus
for two hours. The alcoholic ethereal solution is then filtered,
most of the alcohol and ether distilled off, and the residue al-
lowed to evaporate ; the crystals resulting are recrystallized from
ether.

“ Hydrated pulegonoxime” crystallizes in long needles, and
melts at 157°; when pure, it is sparingly soluble in ether, cold
alcohol, benzene and petroleum ether; it is readily soluble in
dilute acids, but it is not decomposed by cold acids. It is levo-
rotatory, having a specific rotatory power, [a] = — 83.44°.
Molecular weight determinations indicate that it has the simple
molecular formula, C,,H,,NO.,.

1 Barbier, Compt. rend., 114, 126; Ber., 25, 110, Ref.
2Wallach, Ann. Chem., 277, 160.
3Wallach, Ann. Chem., 289, 337.

=

PULEGONAMINE. 241

The hydrochloride, C,,H,,NO,-HCl, is produced by passing
hydrogen chloride into a solution of “ Pleissner’s oxime” in
glacial acetic acid, and is precipitated: from this solution by the
addition of ether. It separates from alcoholic ether in beautiful,
orthorhombic’ crystals, melts at 117° to 118°, and is levorotatory,
[a]> = — 32.43°. Soda precipitates the “hydrated oxime”
(m. p. 157°) from aqueous solutions of this hydrochloric acid
salt.

The following derivatives indicate that the molecule of water
in “hydrated pulegonoxime” is chemically combined.

Benzoyl ester, C,,H,,O - NO- COC,H,, is prepared by treating
the ethereal solution of the “oxime” with benzoyl chloride ; it
crystallizes from dilute alcohol or a mixture of benzene and
ligroine, and melts at 137° to 138° with decomposition.

Acetyl ester, C,,H,,O - NO - COCH,, melts at 149°.

According to more recent researches of Harries,? Beckmann and
Pleissner’s “ hydrated pulegonoxime” should be called pulegone
hydroxylamine ; its constitution is expressed by the following
formula :

‘H,

C

H.C CH,

cee
H

bi HOH

H,C CH,

Oxidation converts it into nitrosomenthone (m. p. 35°) and nitro-
menthone (m. p. 80°).

Pulegone hydroxylamine forms an owalate,* (C,,H,,O,N)C,O,H.,
which crystallizes in needles, and melts with decomposition at
151° to 152°.

With nitrous acid, the hydroxylamine derivative yields a white,
crystalline mass, which is probably a nitroso-amine,* but is ex-
ceedingly unstable.

Pulegone hydroxylamine also reacts with hydriodic acid, giving
rise to 8-amidomenthone.

Pulegonamine, C,,H,,ON, is formed when “ Pleissner’s oxime ”
is warmed with hydriodic acid and red phosphorus.

1Fock, Ann. Chem., 262, 9.
2Harries and Roeder, Ber., 31, 1809.
3Harries and Roeder, Ber., 32, 3357.

16

242 THE TERPENES,

Pulegone semicarbazone,' C,,H,, = N— NH-CO-NH,., dissolves
in cold alcohol, and melts at 172°; it yields pulegone on treat-
ment with boiling acids, even acetic acid being sufficient to de-
compose it.

Bisnitrosopulegone, (C,,H,,O),N,O,.—According to Baeyer and
Henrich,’ this compound is so characteristic that it may be em-
ployed for the identification of pulegone. In order to prepare it,
two cc. of pulegone are mixed with two cc. of ligroine and one ce.
of amyl nitrite ; the mixture is cooled with ice, and treated with
a drop of concentrated hydrochloric acid, the acid being introduced
by a glass rod. In twenty to twenty-five seconds the liquid be-
comes cloudy, and solidifies to a crystalline mass ; it is allowed to
stand for twenty minutes, is filtered, washed with ligroine, pressed
on a porous plate, and again washed with ether. It decomposes
on recrystallization. Baeyer’ regards this compound as a bis-
nitroso-derivative, but it differs from members of this class in
that it yields an owime in addition to a bisnitrosylic acid ; this fea-
ture is explained by the fact that the bisnitroso-group — NO,N—
is joined to the methylene carbon atom, in juxtaposition to the
ketone group in the pulegone molecule. .

Bisnitrosopulegone dissolves in ammonia, yielding an oxime.

Isonitrosopulegone,” C,,H,,NO,, is prepared by the action of
caustic soda on bisnitrosopulegone; it crystallizes in yellow
needles, and decomposes at 122° to 127°.

Pulegondioxime hydrate,’ C,,H,,N,O,, is formed by the action of
hydroxylamine on isonitrosopulegone.

Pulegonbisnitrosylic acid,’ C,,H,,N,O,, results by the action of
hydrogen chloride upon an ethereal solution of bisnitrosopule-
gone. It separates from petroleum ether in slender, colorless
needles, and melts at 115° to 116°.

2-Chloropulegone,’ C,,H,,ClO, which crystallizes in long needles
and melts at 124° to 125°, and diisonitroso-methyl-cyclohexanone,
C_H,,N,O,, are obtained in the same reaction with bisnitrosopule-
gone. The diisonitroso-derivative decomposes at 190°; its for-
mation depends on the elimination of the C,H,-group from the
pulegone molecule. Its diacetate melts at 125° to 130°. The
diisonitroso-derivative yields the anhydride of triisonitroso-methyl-
cyclohexanone, C,H,N,O,, by the action of hydroxylamine ; it melts
at 128° to 129°, and yields an acetate, melting at 139° to 140°. -

Benzylidene pulegone,’ C,,H,,O = CH -C,H,, is formed by the
condensation of pulegone and benzaldehyde with sodium ethylate ;

1Baeyer and Henrich, Ber., 28, 652. :

2Baeyer and Prentice, Ber., 29, 1078.
5Wallach, Ber., 29, 1595; Ann. Chem., 305, 267.

OXIDATION OF PULEGONE. 243

it boils at 202° to 203° under a pressure of 12 mm. On reduc-
tion with sodium and alcohol, it yields benzylpulegol, C,,H,,(OH)-
CH, - C,H,.

Pulegenacetone,' C,,H,,O, is formed by warming a mixture of
pulegone, ethyl acetoacetate, and glacial acetic acid with fused
zine chloride, for ten hours, on the water-bath. It boils at 148°
to 153° under a pressure of 8 mm., solidifies in the receiver, and
crystallizes from light petroleum in prisms, which melt at 72° to
73°. Its oxime is crystalline, melts at 134° to 135°, and yields
a benzoyl derivative, which crystallizes in yellow needles, and
melts at 178° to 179°.

3-Chloro- 4***)-terpadiene,? C,,H,,Cl, is produced by the action
of phosphorus pentachloride on pulegone ; it is a colorless oil, boils
at 101° (25 mm.), has a sp. gr. 0.983 at 19°, and np = 1.49928.
With an excess of bromine, it yields a tetrabromide, C,,H,,CIBr,.
Formic acid converts the chloroterpadiéne into methyl cyclohex-
anone.

Bispulegone,* C,,H,,O,, results by the action of aluminium
amalgam on pulegone ; it crystallizes in needles, melts at 118° to
119°, and is readily soluble in benzene, ether and acetic acid.
When pulegone is reduced with sodium amalgam in an acetic acid
solution, menthone and menthol are also formed.

Oxidation of pulegone.—Pulegone yields acetone and optically
dextrorotatory f-methyl adipic acid, C,H,,O, (m. p. 84.5°), on
oxidation with potassium permanganate.

8-Methy] adipic acid is converted into a lactonic acid, C,H,,0,,
by oxidation ; when the calcium salt of S-methyl adipic acid is
distilled with soda-lime, it yields a ketone, C,H,,O, {-methyl
ketopentamethylene. According to Semmler,* these reactions indi-
cate that S-methyl adipic acid has the following constitution :

HOOC—CH,—CH,—CH(CH, )—CH,—COOH
8-Methy] adipic acid.
ae a,
CO—CH,—CH,—C( CH, )—CH,—COOH H,C—CH—CH, —
H,—CH, wv
y-Valerolactone-y-acetic acid. 8-Methyl1 ketopentamethylene.

1Barbier, Compt. rend., 127, 870.
Klages, Ber., 32, 2564.

sHarries and Roeder, Ber., 32, 3357.
4Semmler, Ber., 25, 3515; 26, 774.

244 THE TERPENES.

Semmler derives the following constitutional formula of pule-
gone from these transformations :

i
{H.
B
=e:

a |

H,C CH;
Pulegone.

This formula has further been proved by Wallach.’ He
showed that when pulegone is boiled with anhydrous formic acid,
or is heated with water in an autoclave at 250°, a hydrolytic de-
composition takes place with the production of acetone and methyl
cyclohexanone (boiling point 169°):

H, H,
‘H H
H,¢ OH, +H—O—H=H,¢ 0H, +CH,-CO.CH,
H, H,
H,

H,;C CH;
Pulegone. Methyl] cyclohexanone. Acetone.

The formyl derivative of cycloheptylenamine (hexahydro-
meta-toluidine), C,H,,NH,, is formed in an analogous manner,
when pulegone is boiled with ammonium formate.

Methyl cyclohexanone,’ C,H,,O, is obtained from pulegone as
above mentioned. It is also formed during the action of concen-
trated sulphuric acid on pulegone,’ by boiling pulegone hydro-
bromide with alcohol and lead hydroxide, by boiling pulegone
with alcohol and basic lead acetate, or when it is distilled with
quinoline.*

It boils at 169°, has the specific gravity 0.915 at 21°, and the
refractive index, np = 1.4456, at the same temperature; M=

1Wallach, Ann. Chem., 289, 337.
2Harries and Roeder, Ber., 32, 3357.
3Zelinsky, Ber., 30, 1532.

SP Ses

METHYL PULEGENATE. 245

32.59. Its oxime melts at 43° to 44°, and the semicarbazone at
180°. |

When methyl hexanone is reduced with sodium and alco-
hol, methyl cyclohexanol (meta-oxyhexahydrotoluene), C,H,,OH, is
formed ; it boils at 175° to 176°.

For the numerous derivatives of methyl cyclohexanone, refer-
ence must be made to the original publications.’

PULEGENIC ACID, C,,H,,0,.

Pulegone forms a liquid dibromide, which yields pulegenic acid
when it is heated with a solution of sodium methylate :

C,H,,OBr, + H,O=2HBr + C,,H,,0>.

This acid boils without decomposition at 150° to 155° as a
pressure of 13 mm.; when distilled at atmospheric pressure, it
decomposes into carbonic anhydride and a hydrocarbon, C,H.,,.
This hydrocarbon boils at 138° to 140°, has the sp. gr. 0. 790 and
refractive index, n, = 1.44, at 20°; it yields a nitrosochloride,
melting at 74° to 75° (Wallach “i

The amide of pulegenic acid crystallizes in woolly needles, and
melts at 121° to 122°. When it is treated with phosphoric an-
hydride, it is converted into the nitrile, which boils at 218° to
220°, has the sp. gr. 0.8935 and index of refraction, ny =
1.47047, at 22°.

The preparation of pulegenic acid from pulegone is accom-
plished by a break in the ring structure ; its formation resembles,
in certain respects, that of campholenic acid from camphor and of
fencholenic acid from fenchone.

Pulegenic acid is an unsaturated compound ; when its solution
in methyl alcohol is saturated with hydrochloric acid gas, the
hydrochloride of pulegenic methyl ester is formed. It boils at 113°
to 116° (13 mm.), and solidifies at a low temperature.

Methyl pulegenate,* C,,H,,0,CH,, boils at 89° to 90° (10 mm. yi
and is formed by the action of a methyl alcoholic solution of
sodium methylate upon the hydrochloride. On acidifying the
alkaline solution which remains after the removal of the methyl

1Wallach, Ann. Chem., 289, 337; 309, 1; $12, 171; 314, 147; Ber.,
29, 1595; 29, 2955; Klages, Ber., 32, 2564; Harries and Roeder, Ber.,
32, 3357; methyl hexanone prepared from 8 -methyl pimelinic acid, see
Einhorn and Ehret, Ann. Chem., 295, 181; Kondakoff and Schindehneiser,
Journ. pr. Chem., 1900 [II], 61, 477; J. von Braun, Ann. Chem., 314,
168; Harries, Ber., 34, 300; Bouveault and Tetry, Bull. Soc. Chim.,
1901 [IIT], 25, 441.

2Wallach, Ann. Chem., 289, 337.

Wallach, Ann. Chem., 300, 259.

246 THE TERPENES.

alcohol and ethereal salt by distillation with steam, the lactone,
C,,H,,O,, is precipitated ; it boils at 125° to 127° (15 mm.).
The acid, C,,H,,O,, produced together with the lactone, boils at
145° to 147° (15 mm.) and at 256° to 260° at 760 mm.; sp.
gr. = 0.9955, np, =1.47547, at 21°. It closely resembles, but is.
not identical with, pulegenic acid; its amide crystallizes from
methyl alcohol in needles, and melts at 152°.

A brominated lactone is formed by treating pulegenic acid with
potassium hypobromite; by the action of alcoholic sodium
methylate, it yields pulegenolide, C,,H,,O,, which melts at 44° to
45°, and boils at 265° to 268°. An omy-acid, C,,H,,O,, is pro-
duced on hydrolyzing the lactone with aqueous alkali ; it melts at
95°, and forms a silver salt.

An oxy-lactone, C,,H,,O,, is formed by oxidizing pulegenic
acid with a cold solution of potassium permanganate ; it melts at
129° to 130°. This compound is also obtained by the action of
moist silver oxide on the brominated lactone above mentioned.
The oxy-lactone is converted into pulegenolide by the action of
phosphorus pentachloride, and subsequent treatment of the product
with sodium methylate.

The ketone, C,H,,O, is produced when the oxy-lactone, C,,H,,O,,
is treated with moderately dilute sulphuric acid, carbon dioxide
being eliminated ; it is a saturated compound, boils at 183°, has
the specific gravity 0.8925 and refractive power, np = 1.44506, at
21°. Its oxime melts at 94°.

When pulegone dibromide is heated, it loses hydrogen bromide
and yields methyl cyclohexanone and m-cresol.

Synthetical (Ortho-iso- (?)) Pulegone, C,,H,,O.

When methyl cyclohexanone, C,H,,O, and acetone are con-
densed by means of alcoholic sodium methylate, a ketone,’ C,,-
H,,0, is obtained, which closely resembles natural pulegone, and
is isomeric, but not identical, with it. If natural pulegone be
termed para-pulegone, then the structure of this synthetical ketone
will be either that of pseudo- or ortho-iso-pulegone. Wallach is
inclined to regard it as an ortho-iso-pulegone, but the investiga-
tions are not yet complete.

Synthetical pulegone is purified by conversion into the semi-
carbazone ; when regenerated from this compound, it boils at 94°
to 95° under 14 mm. pressure, or at 214° to 215° at atmospheric
pressure. It has the specific gravity 0.918 and the refractive

1Wallach, Ber., 29, 1595 and 2955; Ann. Chem., 300, 268.

ISOPULEGOL AND ISOPULEGONE. 247

index, np = 1.46732, at 20°. Its odor is scarcely distinguishable
from that of natural pulegone, but its chemical properties are
widely different. It is strongly dextrorotatory.

It yields a semicarbazone, which exists in two modifications, the
one melting at 70° to 85°, and the second at 144°; both modi-
fications yield the same synthetical pulegone on treatment with
dilute acids.

_ Synthetical pulegone is not converted into methyl hexanone
and acetone by the action of formic or dilute sulphuric acid.

The benzylidene derivative of synthetical pulegone, C,,H,,O =
CH.-C,H,, melts at 83° to 84°.

A compound, C,,H,,O, is also formed during the condensation
of methyl hexanone and benzaldehyde ; it boils at 179° to 183°
under reduced pressure.

Synthetical pulegol, C,,H,,OH, is produced by reducing synthet-
ical pulegone in ethereal or alcoholic solution with sodium. It
is a viscous liquid, has an odor of terpineol, and boils at 103° to
104° (15 mm.), and at 215° under atmospheric pressure. Its
specific gravity at 20° is 0.912 and refractive power, ny = 1.4792.
When treated with phosphoric anhydride, it yields a terpene,
C,,H,,, boiling at 173° to 175°.

Wallach’ suggests the following formula for synthetical pulegone:

ne

H
CH.

" c as ;

H, 6 ||(NCHs

Ortho-isopulegone.

12, ISOPULEGOL, C,,H,,OH, and ISOPULEGONE, C,,H,,0.

An alcohol, C,,H,,OH, corresponding with natural pulegone,
has not yet been obtained free from menthol by the reduction
of pulegone. An alcohol, C,,H,,OH, isopulegol, is, however,
produced from citronellal, C,,H,,0, an aliphatic terpene alde-
hyde. .

Tt results in the form of its acetate by heating citronellal with
an equal weight of acetic anhydride in an autoclave at 180° to

1Wallach, Ann. Chem., 300, 275.

248 THE TERPENES.

200°, for ten or twelve hours ; or by heating citronellal with an-
hydrous sodium acetate for fifteen to twenty hours at 150° to
160° (Tiemann and Schmidt *).

According to Barbier,’ when citronellal is agitated with ten
parts of five per cent. sulphuric acid for twelve hours, isopulegol
is formed, together with menthoglycol, C,,H,(OH),; the latter
compound is also obtained from isopulegol.

According to Tiemann,’ commercial citronellal contains some
isopulegol, together with other compounds; its presence in the
mixture may be recognized by its conversion into isopulegone
upon oxidation.

PRopPERTIES.—Isopulegol has an odor like menthol, boils at
91° under a pressure of 13 mm., and has the rotatory power,
[al = — 2.65°. Its specific gravity is 0.9154 at 17.5°, the re-
ractive index, np = 1.47292, and the molecular refraction, M=
47.20.

Menthoglycol? (menthandiol-3, 8), C,,H,,(OH),, is a compound
closely related to isopulegol. It is formed, together with some
isopulegol and a compound, C,,H,,O (b. p. 185° at 10 mm.), by
agitating citronellal with ten parts of five per cent. sulphuric acid
for twelve hours. It crystallizes from petroleum ether in white
plates, melting at 81° to 81.5°. Acetic anhydride at 100° con-
verts it into a monoacetate (b. p. 137° to 138° at 10 mm.), while
at 150°, in the presence of fused sodium acetate, the acetyl
derivative of isopulegol results. Hydrogen chloride in pres-
ence of glacial acetic acid changes the glycol into a mixture
of two isomerides, C,,H,,Cl-O-COCH,, boiling at 124° to
125° (10 mm.). This glycol may also be obtained directly from
isopulegol.

Isopulegone, C,,H,,O, is formed by the oxidation of isopulegol
with an acetic acid solution of chromic anhydride ;* the product
seems to consist of a mixture of two stereo-isomeric modifications,
which are designated as a- and §-isopulegone.*

According to Tiemann, the mixture of a- and -isopulegone,
obtained by the oxidation of isopulegol, boils at 90° (12
mm.), has the specific gravity 0.9213, the index of refraction,
Np = 1.4690, the molecular refraction, M = 45.98, and the specific
rotatory power, [a], = + 10° 15’, in a one decimeter tube. On
treating with boiling dilute sulphuric acid and alcohol or with

1Tiemann and Schmidt, Ber., 29, 903.

*Barbier and Leser, Compt. rend., 124, 1308.

3Tiemann, Ber., 32, 825.

Tiemann and Schmidt, Ber., 29, 903; 30, 22; Tiemann, Ber., 32, 825.
5Harries and Roeder, Ber., 32, 3357.

ee ed -~ -

B-ISOPULEGONE SEMICARBAZONE. 249

formic acid, methyl cyclohexanone is obtained which is identical in
every respect with the compound produced from natural pulegone.
Isopulegone differs widely from natural and synthetical pulegones
in its chemical behavior. It does not combine with acid sodium
sulphite. When reduced with sodium and alcohol, it yields iso-
pulegol, no menthol being produced ; menthol is not formed by
the action of sodium and alcohol on isopulegol.

a-Isopulegone’ is also obtained in a yield of seventy per
cent. by heating natural pulegone with methyl alcohol and basic
lead nitrate on the water-bath for half an hour ; it is separated
from unchanged pulegone by treating its ethereal solution with
aluminium amalgam, distilling with steam and converting into its
oxime (m. p. 120° to 121°). When regenerated from the latter
compound, a-isopulegone is obtained as a colorless oil, which boils
at 98° to 100° (13 mm.), has a specific gravity 0.9192 at 19.5°,
and a specific rotatory power, la] >= — 7° 8’; when allowed to
stand in contact with dilute sulphuric acid for some time it is
rendered inactive. It is converted into dextrorotatory, natural
pulegone when its alcoholic solution is left in contact with baryta
water for twenty-four hours (Harries and Roeder).

a-Isopulegonoxime, C,,H,,NOH, is formed, together with the f-
derivative, by the action of hydroxylamine on isopulegone. It
melts at 120° to 121°, and is volatile with steam.

$-Isopulegonoxime, C,,H,,NOH, is prepared with the a-modifi-
cation ; it melts at 143° (Harries and Roeder).

According to Tiemann, isopulegone yields two oximes, one
melting at 120° to 121° (a-isopulegonoxime), the other melting
at 134°; the latter is non-volatile with steam and may possibly
be a mixture of the a- and f-oximes.

a-Isopulegone semicarbazone, C,,H,, = N-NH-CO-NH,, crystal-
lizes from dilute alcohol in needles, and melts and decomposes
at 173° to 174° (Harries). According to Tiemann, it melts at
171° to 172°, and is readily soluble in ether.

f-Isopulegone semicarbazone, C,,H,, = N-NH-CO-NH,, melts
at 183° (Harries). According to Tiemann, it melts at 180°, and
is sparingly soluble in ether.

A mixture of the a- and f-semicarbazones melts at 173° to
174°. It is obtained by treating the isopulegone, resulting from
the oxidation of isopulegol, with semicarbazide solution ; it is
separable into the a- and f-derivatives, having the above-de-
scribed properties (Tiemann).

When a-isopulegonoxime (m. p. 121°) or the a-semicarbazone
(m. p. 173° to 174°) is acted upon by boiling dilute sulphuric
acid and alcohol, it yields methyl cyclohexanone.

250

THE TERPENES.

According to Tiemann and Harries, isopulegone is represented

by the formula

Hy
O

ber
H
C

H.
bn,
JH.

u,6 ,

The following table may serve to illustrate some of the points
of difference between natural pulegone, isopulegone and synthet-
ical or ortho-isopulegone.

Natural Pulegone. Isopulegone. Synthetical Pulegone.
Boiling point, 99°to0101°(12mm. )) 90° (12 mm. ). 94° to 95°(14mm. ).
Acid sodium sul- | forms a crystalline | does not yield a
phite, derivative. derivative.

Heated with
formic acid,

yields methyl cy-
clohexanone.

yields methyl cy-
clohexanone.

does not yield
methyl cyclohex
anone.

Reduction with
alcohol and so-
dium,

yields pulegol (?)
containing men-
thol; b. p. 108°

to 110° (14 mm. ).

yields isopulegol,
b. p. 91° (13 mm. )

yields synthetical
pulegol, b. p. 103°
to 104° (15 mm. ),

Oximes, normal oxime, C,9- | a-derivative,C,)H,,-| liquid, b. p. 145°
H,,NOH, m. p. NOH, m. p. 121°. (is mm. ).
118° to 119°. 8-derivative, C,)H,,-
pulegone hydroxy- | NOH, m. p. 148°.
lamine, Cj, )Hj9- | mixture (?), m. p.
NO,, m. p. 157°. | 184°.
Semicarbazones, | m. p. 172°. a-derivative, m. p. | exists in two modifi-
171° to 172°. cations; m. p. 70°
B-derivative, m. p.| to 85°, and 144°.

180°.
mixture (a-and £-),

m. p. 173° to 174°.

18. MENTHENONE, ©,,H,,0.

A ketone, C,,H,,O, was obtained by Urban and Kremers’ by
boiling nitrosomenthene (m. p. 65° to 67°) with dilute hydro-
chloric acid (1:1), and in the year 1899 Wallach? gave it the
name menthenone.

1Urban and Kremers, Amer. Chem. Journ., 16, 401.
2Wallach, Ann. Chem., 305, 272.

EE

ISOCAMPHOR, 251

Menthenone boils at 205° to 208°, and has the specific gravity
of 0.916 at 20°; the ketone prepared from the optically active
and inactive nitrosomenthenes is optically active. It has a de-
cided odor of peppermint (Richtmann and Kremers’).

According to Wallach, menthenone boils at 95° to 97° under
12 mm. pressure, has the refractive index, np = 1.4733, at 20°,
the molecular refraction, M = 46.42, and the specific gravity
0.919 at 20°. 7

Menthenone hydrogen sulphide,’ C,,H,,O - 2H.S, is readily formed
by passing hydrogen sulphide into a solution of the ketone in al-
cohol, and subsequently adding concentrated ammonia. It forms
crystals, melting at 212° to 215°, and is soluble in chloroform
and hot methyl! alcohol.

Nitrosomenthenone, C,,H,,O-NO, is prepared according to
Baeyer’s method for the preparation of bisnitrosopulegone ; it
melts at 115° to 115.5°.

Menthenone phenylhydrazone, C,,H,, = N-NHC,H,, crystallizes
with considerable decomposition from warm alcohol, and melts at
73.5° to 74° (Richtmann and Kremers).

Menthenone is reverted into nitrosomenthene by the action of
hydroxylamine (Urban and Kremers).

When menthenone is reduced with sodium and ether, according
to Beckmann’s method, it yields an oil (possibly a new alcohol,
C,,H,,OH, or unchanged menthenone), and a solid compound (a
pinacone (?)); the latter substance crystallizes from hot methyl
alcohol, and melts at 160° to 162° (Richtmann and Kremers).

Dibenzylidene menthenone, C,,H,,O( = CHC,H,),, results by
the condensation of menthenone and benzaldehyde ; it crystallizes
from hot alcohol in light yellow needles, and melts at 129° to
130°. When reduced with zine dust and glacial acetic acid it
gives rise to the corresponding alcohol, C,,H,,O, which forms
colorless crystals, and melts at 72° to 75° (Wallach).

14. ISOCAMPHOR, C,,H,,0.

When camphoroxime, in glacial acetic acid solution, is
treated with nitrous acid (sodium nitrite), it yields a compound,
C,,H,,N,O,, which Angeli and Rimini? call pernitrosocamphor
and which Tiemann * terms camphenylnitramine ; it melts at 43°.
Pernitrosocamphor is attacked by cold concentrated sulphuric
acid with evolution of nitric oxide and formation of a ketone,

1Richtmann and Kremers, Amer. Chem. Journ., 18, 771.

2Angeli and Rimini, Ber., 28, 1077 and 1127; Gazz. Chim., 26 [IT], 29,

34, 45, 228, 502 and 517; 28 [I], 11.
3Tiemann, Ber., 28, 1079; 29, 2807.

252 THE TERPENES.

C,,H,,O, tsocamphor. ‘This ketone should possibly be classified
with the ketodihydrocymenes.

Isocamphor is also formed by treating isopernitrosofenchone,
C,,H,,N,O,, with concentrated sulphuric acid.

Isocamphor ' is an oil having a pleasant odor, boils with slight
resinification at 214° to 216° under ordinary pressure, and. slowly
changes in the air; it immediately reduces permanganate solution,
and behaves as an unsaturated compound. It combines with
bromine and hydrogen bromide forming additive products, and
seems to differ from dihydrocarvone and dihydroeucarvone. It
is resinified by alkalis ; it does not condense with benzaldehyde or
ethyl formate. The pure ketone is obtained by treating its oxime
with dilute sulphuric acid.

Isocamphoroxime,' C,,H,,NOH, melts at 106°. It is dissolved
unaltered by concentrated sulphuric acid, but is converted into
isocamphor by boiling with dilute sulphuric acid.

Isocamphor semicarbazone, C,,H,, = N-NH-CO-NH., melts at
215°.

Isocamphor bisnitrosochloride, (C,,H,,O),(NOCI),, is produced
by the action of acetyl chloride on a mixture of isocamphor and
amyl nitrite, cooled with ice; it forms small, white crystals, and
melts with decomposition at 120° to 121°.

Tetrahydroisocamphor,' C,,H,,OH, is formed by the reduction of
isocamphor with sodium and alcohol ; it is a heavy, colorless oil,
having a lavender-like odor. It is an alcohol and yields a phen-
ylurethane, which forms colorless crystals and melts at 155°.

Dihydroisocamphor,C,,H.,,O, is formed by oxidizing the preceding
compound with chromic acid ; it is a colorless oil, boiling at 203°.
Its semicarbazone crystallizes in thin, white needles, melting at
162° ; dilute sulphuric acid reconverts it into dihydroisocamphor.

Dihydroisocamphor is stable towards permanganate, and yields
a crystalline acid sodium sulphite derivative.

On mixing dihydroisocamphor with one molecule of benzal-
dehyde and gradually adding an alcoholic solution of sodium
ethylate (one molecule), benzylidene dihydroisocamphor,’ C,,H,,O =
CH-C,H,, is formed ; it crystallizes from alcohol in small, white
needles, melting at 217°. The formation of this compound indi-

eates that dihydroisocamphor contains the group —CO—CH,—.
£

- When isocamphor is oxidized with an alkaline solution of

potassium permanganate, it yields a-isopropyl glutaric acid,

C,H,,0,, which crystallizes in white needles and melts at 96° ; it

has been synthetically prepared by W. H. Perkin.* It forms an
1Compare M. Spica, Gaz. Chim. Ital., $1 [IT], 286.

2Rimini, Gazzetta (1900), 30, 596.
3W. H. Perkin, jun., Journ. Chem. Soc., 69, 1495.

Pe oes

—

a hen a oT" 6

A°-MENTHENE-2-ONE. 253

anhydride, C,H,,O,, which crystallizes in long needles, and melts
at 60°. It is converted into succinic acid by oxidation with
chromic acid, and also gives rise to-an anilide, melting at 160°.

It may further be mentioned that a ketone,’ C,,H,,O, isomeric
with camphor, is formed by the dry distillation of 3-methyl-6-iso-
propyl-d’-cyclohexenone carboxylic acid, C,,H,,O-COOH ; it is an
oil, having a camphor-like odor, and boils at 217° to 219°. Its
oxime forms beautiful, monoclinic crystals.

f-Isocamphor, C,,H,,OH, is an unsaturated alcohol which
Duden’ obtained by the action of nitrous acid on camphenamine,
C,,H,,NH,; it sublimes in long needles having the odor and
appearance of camphor, and melts at 102°. It has the specific
rotatory power, [a] = + 17.65°, in methyl alcohol. Its phenyl-
urethane crystallizes from petroleum in long needles and melts at
BS Bla

15. PINOLONE, C,,H,,O, and PINOLOL, C,,H,,OH.

Wallach * obtained the ketone, pinolone, by treating isopinole
dibromide, C,,H,,OBr,, with zinc dust and glacial acetic acid, and
also by the reduction of pinole tribromide. It has an odor recall-
ing that of amyl acetate; it boils at 214° to 217°, has a specific
gravity 0.916 and refractive index, np = 1.46603, at 20°.

Pinolonoxime, C,,H,,NOH, boils at 150° under a pressure of
15 mm.; on reduction it yields a base, the carbamide of which
crystallizes from methyl] alcohol and melts at 186°.

Pinolone semicarbazone, C,,H,,—= N-NH-CO-NH,, melts at 158°.

Pinolol, C,,H,,OH, is the alcohol obtained by reducing pinolone
with sodium and alcohol. It possesses a linalool-like odor, boils
at 108° under 15 mm., has a specific gravity 0.913 and an index

of refraction, np = 1.47292, at 20°.

16. 4°-MENTHENE-2-ONE, C,,H,,0.

According to Harries,* when hydrobromocarvone is reduced in
methyl alcoholic solution with zine dust, about one-quarter of the
product consists of carvone and the remainder is a ketone, C,,H,,O,
called 4°-menthene-2-one.

It is a yellow colored oil, boils at 227° to 228°, or at 96° to
97° under 9 mm. pressure; it has a sp. gr. 0.9411 at 10° and
0.9351 at 19°, and a specific rotatory power, [a] p= + 49.5°, in
a 10 cm. tube.

1J. A. Callenbach, Ber., 30, 639.

2Duden and Macintyro, Ann. Chem., 313, 59.

3Wallach, Ann. Chem., 306, 275; 281, 154; Ber., 28, 2710.
4Harries, Ber., 34, 1924.

254 THE TERPENES,

Its semicarbazone crystallizes in plates and melts at 173° to
174°; its oxime crystallizes in large prisms and melts at 75° to
77°. The hydrogen sulphide derivative, 2C,,H,,O- HS, crystallizes
in lustrous needles and melts at 222° to 225°.

The oxaminoxime, C,,H,,(NOH)(NH,O8), crystallizes with one-
half molecule of water in needles, and melts at 95° to 97° ; it forms
an oxalate, melting at 130° to 135°. When it is oxidized byacurrent
of air, it gives rise to a dioxime, C,,H,,(NOH),, which crystallizes in

colorless prisms and melts with decomposition at 194° to 196°.

When 4°-menthene-2-one is reduced with zine dust and alco-
holic sodium hydroxide, it yields dextro-carvomenthone. When re-
duced with aluminium amalgam, it gives a dimolecular compound,
C,,H,,O,; the latter yieldsa phenylhydrazone, melting at 260°.

The ketone unites slowly with hydrobromic acid, forming a
yellow oil.

17. TERPINEOL, C,,H,,OH.

The name terpineol was formerly used to designate a substance
which to-day is recognized as a mixture of isomeric alcohols,
C,,H,,OH. It will be well first to consider the preparation and
properties of this mixture, which was termed “ terpineol,” before
entering into a discussion of the individual alcohols contained in
it. These alcohols occupy an intermediate position between di-

pentene and terpine:
CoH See CoHnOH 2 CwHe(OH),
Dipentene. Terpineol. Terpine.

Therefore, those terpenes which can be converted into terpine
may also be transformed into “ terpineol ” by the addition of one
molecule of water, while ‘‘terpineol” may also be obtained by
the elimination of water from terpine hydrate.

Deville’ probably obtained “ terpineol ” as a by-product in the
preparation of terpine hydrate from turpentine oil. According
to Flawitzky,’ “terpineol” is prepared when one part of levoro-
tatory turpentine oil is mixed with one-half part of sulphuric
acid and one and one-half parts of ninety per cent. alcohol, the
mixture being allowed to stand for twelve hours.

Tilden * first obtained “terpineol” from terpine hydrate, and
Wallach* more closely defined the conditions under which ‘ ter-
pineol” could be most conveniently prepared from this com-
pound. He found that dilute phosphoric acid gave relatively

1Deville, Ann. Chem., 71, 351.

2Flawitzky, Ber., 12, 2354.

sTilden, Journ. Chem. Soc., 1878, 247; 1879, 287; Ber., 12, 848; Jahresb.

Chem., 1878, 1132.
4Wallach, Ann. Chem., 230, 247 and 264.

TERPINEOL. 255

small quantities of terpenes, and a large yield of “ terpineol.”
In order to prepare it, twenty-five grams of terpine hydrate
are boiled with fifty cc. of a twenty per cent. solution of phos-
phoric acid in a reflux apparatus, for fifteen minutes ; the product
is distilled in a current of steam, and the resultant oil submitted
to a fractional distillation, the “ terpineol ” being contained in the
fraction boiling at 215° to 218° (Wallach).

The French chemists Bouchardat and Voiry’ prepared ‘ ter-
pineol ” by the action of very dilute sulphuric acid (1 to 1000)
on terpine hydrate ; they showed that five-sixths of the resulting
“terpineol ” solidified at — 50° to crystals, melting at 30° to 32°,
This product is designated as ‘‘ solid terpineol.”

It is certain that solid terpineol is also contained in Wallach’s
“terpineol,” ? although for some time it was impossible to isolate
the solid compound from the liquid product.

If terpine be given the formula :

Terpine.

it will be seen that three isomeric, unsaturated alcohols, C,,H,,OH,
may be derived from it, thus:

Ta. Ila. II.
H, A, ie
OH OH
oS
H, Hq. H, H, H, H,
H,¢ OH, HQ {H « HC $4,
H
H H ;
H.C CH, H,¢ 0H, HS OH;
A!-Terpen-4-ol. A*-Terpen-1-ol. A«®)-Terpen-1-ol.

1Bouchardat and Voiry, Compt. rend., 104, 996; Ber., 20, 286.
*Tiemann and R. Schmidt, Ber., 28, 1781; Semi-Annual Report of Schim-
mel & Co., April and May, 1901, 75.

256 THE TERPENES.

By totally different methods, Wallach and Baeyer came to the
same conclusion, that solid terpineol (m. p. 35°) should be
considered as a 4'-terpen-4-ol, expressed by formula Ia. This
formula, however, is hardly conformable to the results of experi-
ments which have more recently been published by Wallach,’ and
by Tiemann and Semmler ;’ according to their researches it ap-
pears possible, and even probable, that terpine should be repre-
sented by the formula :

COH
us
H;C CH;
Terpine.

Of the three terpenols which may be derived from this terpine,
one has the constitution represented in formula III ; the other two
have the formulas :

Ib. IIb.
H, Hy,
: y HH
H, H H, H,
H, H, H, H,
H H
OH
H;C CH; H, ‘Nu,
A!-Terpen-8-ol. A*®)-Terpen-1-ol.

Formula Ib is to be regarded as expressing the constitution of
solid terpineol (m. p. 35°), since it represents the facts at present

known better than formula Ia. This formula was first proposed

by G. Wagner.®

1Wallach, Ber., 28, 1773.
2Tiemann and Semmler, Ber., 28, 1778.
3G. Wagner, Ber., 27, 1652.

goa Aes

TERPINEOL. 257

It now remains to consider the nature of the oily constituent
which occurs, together with solid terpineol (m. p. 35°), in Wal-
lach’s ‘‘terpineol.” . Baeyer has synthetically prepared a solid
alcohol, melting at 69° to 70°, which he calls 4*®-terpen-1-ol,
corresponding to formula III; this alcohol and its acetate yield
blue nitrosochlorides, hence, according to Baeyer, the alcohol and
its acetate must contain a tertiary-tertiary double linkage, since
only those compounds possessing such a double linkage are capable
of producing blue nitrosochlorides. Baeyer recognized this ter-
pinol in the liquid “ terpineol” prepared from terpine hydrate by
means of oxalic or phosphoric acid.

It is quite certain that liquid “ terpineol” contains a mixture of
isomeric terpinols. The chemists of Schimmel & Co." have care-
fully investigated this liquid product, and, by submitting it to
continued cold, have isolated the solid terpineol, m. p. 35°,
and an isomeric terpineol, melting at 32° to 33°; the two com-
pounds are readily distinguished by their chemical and physical
properties.

Liquid terpineols have been isolated from camphor, cardamom,’
erigeron, kesso,® kuromoji,* and marjoram? oils ; but since it has
been determined that the terpineol from cardamom oil may be ob-
tained in a crystalline form (m. p. 35°), it is possible that the ter-
pineols from the other oils may be procured in a crystalline con-
dition.®

Wallach’s “ terpineol ” is an optically inactive liquid and con-
tains terpineol of the melting point 35° and terpineol of the
melting point 32° as its chief constituents.

Liquid ‘terpineol” is readily converted into dipentene dihy-
drochloride, dihydrobromide, etc., when the halogen hydrides
are passed into its ethereal solution. Terpine hydrate is easily
formed when it is acted upon by dilute acids.

“Terpineol” is an unsaturated compound; when bromine is
added to its solution in petroleum ether, a bromide is produced,
which crystallizes on cooling with solid carbon dioxide and ether,
but it becomes liquid again at higher temperatures. When it is
treated with an excess of bromine, dipentene tetrabromide results

(Wallach).

1Schimmel & Co., Semi-Annual Report, April and May, 1901, 75.
2Weber, Ann. Chem., 238, 98.

3Bertram and Gildemeister, Arch. Pharm., 228, 483.
4Kwasnick, Ber., 24, 81.

5Biltz, Ber., 32, 995.

6Schimmel & Co., Semi-Annual Report, Oct., 1897, 11.

17

258 THE TERPENES.

TERPINEOL MELTING AT 35°.

It has been mentioned that Bouchardat and Voiry isolated a
solid terpineol from the liquid reaction-product obtained by heating
terpine hydrate with very dilute sulphuric acid. This solid aleohol
was called “ terpilenol” or ‘ caoutchin hydrate” ; it melted at 30°
to 32°, and boiled at 218°. It was also obtained in the form of
its acetyl ester by the continued heating of dipentene with glacial
acetic acid at 100° (Bouchardat and Lafont’).

It is worthy of notice that inactive, solid terpineol occurs in
the form of its acetate in cajuput oil (Voiry’). The chemists of
Schimmel & Co.’ have made a careful investigation of the chem-
ical and physical constants of pure, inactive terpineol from caju-
put oil and also of its derivatives ; they found that these proper-
ties agreed completely with those of solid terpineol melting at 35°.

Kremers * has found terpineol (m. p. 35°) in the oil of Erigeron
canadensis.

Terpineol (m. p. 35°) is also obtained by the action of formic
acid on geraniol at a temperature of 15° to 20° ; terpinyl formate
is the primary product of this reaction, and yields the inactive
terpineol on hydrolysis. A similar conversion of geraniol into
terpineol is accomplished by the action of acetic acid containing
one or two per cent. of sulphuric acid ; this reaction takes place
slowly at the ordinary temperature, rapidly on warming. By
shaking with five per cent. sulphuric acid for ten days, and boil-
ing the terpine hydrate thus formed with dilute sulphuric acid,
geraniol may be converted into a liquid “ terpineol” identical with
that formed from pinene (Stephan °).

The solid terpineol, sold by Schimmel & 'Co., served as the
material which was used by Wallach and by Baeyer in the follow-
ing described experiments. It melts at 35° to 36°, boils at 98°
to 99° (10 mm.) or 218.8° to 219.4° (752 mm.), has the specific
gravity 0.9391 at 15° or 0.9345 at 20°, and the index of refrac-
tion, np = 1.48132 at 20° (Schimmel & Co.*).

According to Tiemann and Schmidt,° terpine hydrate is quan-
titatively formed, when terpineol is agitated with benzene and a
five per cent. solution of sulphuric acid for five days.

The behavior of terpineol towards dehydrating agents was the
subject of a systematic investigation by Wallach and Kerkhoff’ ;

1Bouchardat and Lafont, Compt. rend., 102, 1555.

2Voiry, Compt. rend., 106, 1538.

3Schimmel & Co., Semi-Annual Report, April and May, 1901, 76.

4Kremers, Pharm. Rundschau, 13, 137.

5K. Stephan, Journ. pr. Chem., 60 [II], 244.

6Tiemann and Schmidt, Ber., 28, 1781.
TWallach and Kerkhoff, Ann. Chem., 275, 103.

rt a Be Ee Ge

Oy PR ee ee

TERPINYL METHYL ETHER. 259

their researches were carried out in the same direction as previous
investigations of Wallach * regarding the liquid “ terpineol.”

Dipentene is produced when solid terpineol is heated with acid
potassium sulphate at 180° to 190°. ‘Terpinene, cineole, ter-
pinolene and traces of dipentene are formed when it is boiled with
dilute sulphuric acid ; almost the same result is obtained by boil-
ing terpineol with twenty per cent. phosphoric acid, but in this
case no dipentene results. On boiling terpineol with a solution of
oxalic acid or with anhydrous formic acid? for a short time, the
product consists chiefly of terpinolene ; when the boiling is of
longer duration considerable quantities of terpinene and small
amounts of cineole are obtained, together with terpinolene.

The primary reaction-product obtained by the removal of water
from terpineol consists of the very unstable terpinolene ; at higher
temperatures this hydrocarbon is transformed into dipentene,
while by the action of acids it is converted into terpinene.

Terpinyl formate is formed, as above mentioned, by the action
of formic acid on geraniol at 15° to 20°.

Terpinyl acetate,’ C,,H,,O-COCH,, is obtained when terpineol
is heated with sodium acetate and acetic anhydride for forty-five
minutes ; the yield is about eighty-four per cent.

Terpinyl phenylurethane,

©

as
OCH,

NHC,H,

is obtained when equal parts by weight of terpineol and phenyl
carbimide are allowed to remain in a closed vessel for several
days; the solid reaction-product is washed with petroleum ether,
and crystallized from warm alcohol. It dissolves readily in ether,
and melts at 113° (Wallach and Kerkhoff*).

Wallach’ had previously obtained this urethane from liquid
“‘ terpineol.”

Terpinyl methyl ether, C,,H,,OCH,, is produced when crys-
tallized terpineol is dissolved in three times its amount of toluene,
and boiled with an excess of the liquid alloy of potassium and
sodium in a flask, fitted with a reflux condenser, for eight hours ;
the liquid is then cooled, decanted from unchanged alloy, and
treated with methyl iodide. The reaction commences at a moderate

1Wallach, Ann. Chem., 230, 268; 239, 20.

2Wallach, Ann. Chem., 291, 342.

3Schimmel & Co., Semi-Annual Report, Oct., 1897, 64.
4Wallach and Kerkhoff, Ann. Chem., 275, 103.

260 THE TERPENES.

temperature, and is complete after warming on a water-bath for
one hour. The potassium and sodium iodides are filtered off,
and the filtrate is submitted to a fractional distillation. The
resultant terpinyl methyl ether is a mobile liquid, which boils at
212°, smells like cymene, and is vigorously attacked by per-
manganate (Baeyer’). It combines with hydriodic acid ina glacial
acetic acid solution to form a hydriodide, which yields the methyl]
ether of tertiary menthol by reduction with acetic acid and zine

dust.
OH,

(h

OH,
Tertiary menthyl methyl] ether.

Terpineol dibromide, C,,H,,OH - Br,, results by the gradual ad-
dition of two atoms of bromine to a well cooled solution of solid
terpineol in glacial acetic acid ; it is precipitated from this solu-
tion by water, forming a heavy oil.

When this bromide is digested with an excess of moist silver
oxide or lead hydroxide on the water-bath, pinole hydrate,
C,,H,,O OH, is formed, together with a small quantity of pinole ;
large quantities of pinole, C,,H,,O, are obtained, together with a
small amount of cymene, when terpineol dibromide is heated
with sodium alcoholate (Wallach ’).

Baeyer* states that when the dibromide of Wallach’s liquid
“terpineol” is treated with a solution of two molecules of hy-
drogen bromide in glacial acetic acid, 1, 2, 4 (or 1, 2, 8 (?))-tri-
bromoterpane, C,,H,,Br,, is produced ; this is a liquid, which, on
bromination in an acetic acid solution, is converted into dipentene
tetrabromide.

According to Wallach,‘ when 1, 2, 4 (or 1, 2, 8 (?))-tribromo-
terpane is heated with sodium methylate, the bromine atom 2 is
replaced by a methoxyl-group, whilst the remaining two atoms of
bromine are eliminated as hydrogen bromide, and optically inactive

carveol methyl ether results. Optically active carveol methyl -

ether is formed, as already mentioned, by reducing the bromide,

1Baeyer, Ber., 26; 2560; 26, 826.
2Wallach, Ann. Chem., 277, 113.
3Baeyer, Ber., 27, 440.

4Wallach, Ann. Chem., 281, 140.

TERPINEOL NITROSOCHLORIDE. 261

C,,H,,BrOCH,, which is obtained by treating limonene tetra-
bromide with sodium methylate. Carveol methyl ether yields in-
active carvone by oxidation with chromic anhy«ride.

The following formulas illustrate the transformation of solid
terpineol into carvone :

hi ie
DN CBr
H, via H, HBr
a al
H, ‘\ H, H, H,
OH OH
H, C3H,
Terpineol (A!-terpen-4-ol ). Terpineol dibromide.
H; _2 i
Br
H, HBr H H(OCH;)
“ =
H, ae BK H,
am
13H, C;H,
1,{2, 4-Tribromoterpane. oe Carveol methyl ether.
bo
O '
a
HC H,
3H,
Carvone.

The development of those formulas which indicate that terpineol
should be regarded as a 4'-terpen-8-ol is given on page 198.

Terpineol nitrosochloride, C,,H,,(OH) - NOCI, is obtained by add-
ing eleven cc. of ethyl nitrite to a solution of fifteen grams of
crystallized terpineol in fifteen cc. of glacial acetic acid, well
cooled by a freezing mixture, and subsequently adding very slowly
a mixture of six cc. of concentrated hydrochloric acid and six ce.
of glacial acetic acid. When the reaction is complete, water is
added and the nitrosochloride separates as an oil which soon
solidifies. The yield is quantitative ( Wallach’).

It is a comparatively stable compound and may be recrystal-
lized from methy] alcohol or ethy] acetate, melting at 102° to 103°.

1Wallach, Ann. Chem., 277, 121.

262 THE TERPENES.

When hydrogen chloride is eliminated from terpineol nitroso-
chloride, oxydihydrocarvoawime,' C,,H,,(OH)NOH, melting at 133°
to 134°, is obtained ; this compound, when boiled with dilute
acids, loses water and hydroxylamine, yielding a mixture of car- -
vacrol and inactive carvone. It may, therefore, be concluded
that in terpineol the ethylene linkage is, without doubt, in the
4'-position (Wallach’).

Terpineol nitrosate, C,,H,,(OH)-N,O,, was prepared by Wal-
lach,* but has not been carefully studied.

Terpineol nitrolpiperidide,* C,,H,,(OH)-NO-NC,H,,, is prepared
by the interaction of the nitrosochloride with piperidine. It erys-
tallizes from methyl] alcohol in needles and dissolves sparingly in
ether from which it separates in prisms, melting at 159° to 160°.

Terpineol nitrolanilide, C,,H,(OH)-NO-NHC,H,, is obtained
by warming ten grams of terpineol nitrosochloride with ten cc. of
aniline and twenty or twenty-five cc. of alcohol. The reaction-
mixture is diluted with a little water and yields splendid, yellow
crystals on cooling. These are washed with a little ether and,
when recrystallized from alcohol, form colorless prisms, which
melt at 155° to 156°.

Terpineol yields various products on oxidation with potassium
permanganate ; the first of these is a compound, C,,H,,O,, which
must be regarded as methyl isopropyl trioxyhexahydrobenzene,
or, according to Baeyer, trioryterpane. By further action of per-
manganate, trioxyterpane loses four atoms of hydrogen, and forms
the keto-lactone, C,,H,,O,, a compound which is likewise derived
from a number of other terpene derivatives ; hence, in order to
prepare pure trioxyterpane, an excess of permanganate must be
carefully avoided (Wallach °).

Trioxyhexahydrocymene fa; 2, 8-trioxyterpane or 1, 2, 8-trioxy-
menthane |, C,,H,,O,.—For the preparation of this compound, dis-
solve one hundred and fifty grams of permanganate in six liters of
water contained in a metallic, double-walled vessel ; add one hun-
dred and five grams of melted terpineol, and agitate for several
minutes on a shaking-machine, keeping the liquid well cooled by
passing water through the space between the walls of the vessel.
The reaction is complete in a very short time. Filter off the
manganese oxides, evaporate the filtrate to dryness while passing
a current of carbonic anhydride through the liquid, and extract

1Wallach, Ann. Chem., 291, 342.
2Wallach, Ber., 28, 1773.
3Wallach, Ann. Chem., 277,121.
4Wallach, Ann. Chem., 281, 140.
5Wallach, Ann. Chem., 275, 150.

ae

ME. RS AO ROR all oh

ot etal gla
—

es eNO ee eee eee

KETO-LACTONE. 263

the dry residue with alcohol. On evaporation of the alcohol, the
product soon solidifies to a light colored, crystalline mass. This
is best distilled in vacuum, and boils at 170° to 180° under 11
mm. pressure; the distillate solidifies, and is rubbed up with
ether, which readily dissolves the impurities. When purified in
this manner, trioxyhexahydrocymene is almost insoluble in ether,
somewhat sparingly soluble in chloroform, and separates from a
mixture of alcohol and ether in transparent crystals. It melts at
121° to 122°, and boils above 300° with slight decomposition.

It is very readily soluble in water, and is precipitated from its
concentrated aqueous solution by alkalis ; it yields iodoform when
treated with iodine and alkalis, and forms carbon tetrabromide by
the action of bromine and alkalis. Phosphoric chloride converts
it into a chloride.

Trioxyhexahydrocymene loses three molecules of water and
forms cymene, when it is heated with dilute sulphuric acid

(Wallach *),
C19 H903 — 3H. 20 —" C,H,

Under suitable conditions it may part with but two molecules
of water, yielding carvenone, C,,H,,O:

Cio H 90; — 2H,0 = Cio H,,0.

According to Ginzberg,' trioxymenthane is converted into
cymene, and the diacetate of a glycol, when it is heated with three
molecules of acetic anhydride for six hours at 150°. On hydrol-
ysis, the diacetate yields the glycol, C,,H,,(OH),, isomeric with
pinole hydrate; it crystallizes from petroleum ether in triclinic
prisms, melts at 63° to 64°, and boils at 259° to 260° under 754
mm. pressure. Oxidation with dilute permanganate converts the
glycol into an inactive tetrahydric alcohol, C,,H,,O,, which is
isomeric with limonetriol, and melts at 168.5° to 169.5°. The
glycol is regarded as a 4*-menthene-1 : 2-diol.

When trioxyterpane is heated with acetic anhydride at 200°,
more cymene than glycol is produced ; when heated with acetyl
chloride, pinole hydrate (m. p. 130.5° to 131°) and a little
cymene are formed (Ginzberg ’). |

Keto-lactone,® C,,H,,O,, is quantitatively formed by oxidizing
trioxyterpane, C,,H,,O,, which is also almost quantitatively ob-
tained by the oxidation of terpineol as described above. The

_ following method is well adapted for the preparation of this com-

pound.
1Wallach, Ann. Chem., 277, 110 and 122.

2A. Ginzberg, Ber., 29, 1198.
3Wallach, Ann. Chem., 275, 153.

264 THE TERPENES.

Eleven grams of trioxyterpane are dissolved in seven cc. of
warm water; the solution is then well cooled, and treated very
carefully with a solution of eight grams of chromic anhydride
in twenty ec. of sulphuric acid, sp. gr. 1.25. The reaction is ac-
companied by a rapid rise in the temperature; the chromic acid
is reduced to a sulphate, and an oil separates, which solidifies in
large crystals on cooling. Additional quantities of this sub-
stance may be obtained by extracting the aqueous chromium sul-
phate solution with chloroform. It is washed with a small
quantity of water and ether, and crystallized from hot water.

This keto-lactone is characterized by its exceptional power of
- erystallization ; it separates in monoclinic pyramids, and forms
quite as well defined crystals as any member of the terpene series.
It boils at about 330° without decomposition, and melts at 62°
to 63°.

This compound, C,,H,,O,, yields an oxime, melting at 77°, as
well as a semicarbazone, melting at 200°, and, on the other hand,
is converted into the potassium salt of an acid, C,,H,,O,, by the
action of potassium hydroxide ; therefore, Wallach’ assumes that
it isa keto-lactone. Wallach’ further determined that it is readily
converted into acetic acid and terpenylic acid by oxidation with
permanganate.

Tiemann and Semmler * also obtained this keto-lactone as a by-
product in the oxidation of commercial pinene with permanganate.
‘They determined its constitution in much the same manner as
‘Wallach, and arrived at the same constitutional formula, accord-
ing to which it is represented as _ methyl-3'-ethyl-3-heptanon-6-
olide-1-3'. Tiemann and Schmidt * confirmed these results ; they
also showed that the keto-lactone, C,,H,,O,, is formed, together
with terpenylic acid, by the oxidation of terpineol and of trioxy-
lhexahydrocymene with a mixture of chromic and glacial acetic
acids.

According to Mahla and Tiemann,’ oxidation with chromic and
sulphuric acids converts methoethylheptanonolide (keto-lactone)
into terpenylic acid,’ C,H,,O,, while oxidation with nitric acid
gives rise to terebic acid, C_,H,,O,.

According to Tiemann,’ the keto-lactone melts at 64°, and its
oxime, C,,H,,O,.NOH) (see above), crystallizes in rhombs, and

162
tWallach, Ber., 28, 1773.

2Wallach, Ann. Chem., 277, 118.

3Tiemann and Semmler, Ber., 28, 1778.
4Tiemann and R. Schmidt, Ber., 28, 1781.
5Mahla and Tiemann, Ber., 29, 2621.
6Mahla and Tiemann, Ber., 29, 928.
™Tiemann, Ber., 29, 2616.

oe el 4" ve

amd)

Le: A lee mee Bana | a!

ee:

—

a

——eeE>EEEE>——

KETO-LACTONE.

265

melts at 79° to 80°; when heated with concentrated sulphuric
acid at 100°, the oxime is converted into acetic acid and a base,

methyl-2-aminoethyl-3-pentolide, C,H,,O,N H,,.

The keto-lactone is also formed by treating the pinonic acids
with dilute sulphuric acid (see under pinene).

According to Bredt, terpenylic acid is readily obtained, when
solid terpineol is treated with a chromic acid mixture.

If we accept the constitution of terpenylic acid as represented
by the formula proposed by Wallach * and supported by Schryver,?
we may formulate the oxidation of terpineol in the following

manner :

i
H, ce
H H,
£) --
‘H

|

COH
H; CH,
Terpineol.
H;
10 ae
H,C OOH
H, Fe —_
H
JOH
Hy; CH,

Intermediary product.

OOH
HF 909
H.C CH, “eo
‘H
\
H.C 08,

Terpenylic acid.

1Wallach, Ann. Chem., 259, 322.
2Schryver, Journ. Chem. Soc., 1893, 1327.

OH
HC CH,

Trioxyhexahydrocymene.

H
im

(—-—

fn
H;C CH,
Keto-lactone, C,)H,,0;
(Methyl-3!-ethyl-3-
heptanon-6-olide-1-3').

266 THE TERPENES.

The above-described terpineol (m. p. 35°) is optically inactive,
but a number of optically active terpineols have been obtained
and will be briefly mentioned here.’

Semmler’ obtained an active terpineol, C,,H,,OH, by the sub-
stitution of the hydroxyl-group for an atom of chloride in limo-
nene hydrochloride ; it boils at 215°, has the odor of hawthorn
blossom and lilac, and its optical rotation is of the same sign as
that of the limonene derivate from which it is produced.

Bouchardat and Tardy * obtained a strongly dextrorotatory ter-
pene (pinene) from the eucalyptus oil of Eucalyptus globulus ; by
treating this terpene with anhydrous formic acid at a low temper-
ature terpinyl formate is produced, which yields a solid, dextro-
rotatory terpineol on hydrolysis. This terpineol melts at 33° to
34°, boils at 218° and has the specific rotatory power, [a]>=
+ 88°.

The fraction boiling at 150° to 164° at 14 mm. pressure of
Ceylon cardamom oil contains a terpineol,* melting at 35° to 37°;
it is dextrorotatory, [a], = 83°31’, at 21°. It yields a terpinyl
phenylurethane, melting at 112° to 113°, which is optically ac-
tive, [a] p = + 33°58’, at 20°. It also forms a nitrosochloride,
and nitrolpiperidide, melting at 151° to 152°, while the nitrol-
piperidide obtained from inactive terpineol melts at 159° to 160°.

An active terpineol is also obtained from the oil of lovage®; it
boils at 217° to 218°, melts at 35°, and is dextrorotatory,
[a]>= + 79°18’, at 22°. It yields a terpinyl phenylurethane
(m. p. 112°), and a nitrolpiperidide (m. p. 151°).

Godlewsky ° obtains a levorotatory terpineol by treating French
turpentine oil with alcoholic sulphuric acid, according to Flaw-
itzky’s method, the mixture being shaken and the product poured
onto ice. The reaction is allowed to proceed for ten hours. The
resulting terpineol melts at 34°, has the specific rotatory power,
[a] > = — 95°28’, in an alcoholic solution. Oxidation with a
one per cent. solution of permanganate converts it into triowymen-
thane (menthanetriol or triowyhexahydrocymene), C,,H,,O,; when
this compound is oxidized with chromic acid, the keto-lactone
(methoethylheptanonolide), C,,H,,O,, is formed, which’ differs by its
optical activity, Lala p=t 5D. 3° : in alcoholic solution, and a con-
siderably lower melting point (45° to 46°), from the keto-lactone,

1For optically active terpineol prepared by action of alcohol and nitrous
acid on dextro- or levo-pinene, see P. Genvresse, Compt. rend., 132, 637.

2Semmler, Ber., 28, 2189.

3Bouchardat and Tardy, Compt. rend., 121, 1417.

4Schimmel & Co., Semi-Annual Report, Oct., 1897, 11.

5Schimmel & Co., Semi-Annual Report, April, 1897, 27.
6 J. Godlewsky, J. Russ. Chem. Soc., 31, 203; Chem. Centr., 1899 [I], 1241.

OPTICALLY ACTIVE TERPINEOLS. 267

C,,H,,O,, derived from inactive terpineol, which melts at 63° to
64°. This keto-lactone is perhaps identical with the optically
active keto-lactone (active methyl ketone of homoterpenylic acid),
C,,H,,O,, melting at 48° to 49°; which Baeyer’ obtained from
levorotatory trioxyterpane (m. p. 97° to 98°), prepared indirectly
from optically active 1:8-oxybromotetrahydrocarvone, C,,H,,BrO-
OH).

Tn the oxidation of the above-mentioned levo-terpineol, optic-
ally active terpenylic acid is also produced.

According to Stephan,” when levo-linalool is heated with
acetic anhydride during five to eight hours at 150° to 160°, a
product is obtained which consists of about eighty-five parts of
geraniol and fifteen parts of dextro-terpineol ; the latter separates
out in a crystalline condition after repeated fractionation and cool-
ing in a freezing mixture.

Dextro-terpineol is also produced in larger quantities by treat-
ing linalool with acetic acid containing a little sulphuric acid.
Formic acid also converts |-linalool into d-terpineol, and d-lina-
lool into |-terpineol, if the reaction proceeds below 20° ; a crys-
talline terpineol is formed in each case.

The crystalline active modifications of terpineol are readily
obtained in the form of their acetates by the action of glacial
acetic and sulphuric acids on the limonenes, or of glacial acetic
acid and zinc chloride on the pinenes.*

According to Biltz,‘ the essential oil of Origanum majorana
(marjoram oil) contains a dextrorotatory, liquid “terpineol,” the
presence of which is shown by its oxidation products, trioxy-
hexahydrocymene, C,,H,,O,, and the keto-lactone, C,,H,,O,.

A solid, levorotatory terpineol is also said to be contained in

niaouli oil.

The active and inactive modifications of terpineol are alike in
their chemical behavior ; a few derivatives, however, differ slightly
in their melting points.

Since terpineol (m. p. 35°) shows such a close relation to so
many compounds of the terpene series, and is of importance for
the determination of the constitution of these compounds, the fol-
lowing table is introduced in order to render more apparent the
close relationship of terpineol with other terpene derivatives.

1Baeyer and Baumgaertel, Ber., 31, 3208.

2K. Stephan, Journ. pr. Chem., 58 [II], 109.

8Ertschikowsky, Journ. d. russ. phys.-chem. Ges., 28, 132; Abs. Bull. Soe.
Chim., 16 [III], 1584.

4W. Biltz, Ber., 32, 995.

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ISOMERIC TERPINEOL. 269

18, ISOMERIC TERPINEOL, C,,H,,OH, MELTING AT 69° TO
70°. (4‘®)-TERPEN-1-OL.)

When the tribromoterpane (m. p. 110°), which Wallach ob-
tained by brominating dipentene dihydrobromide, is reduced with
zine dust and acetic acid, it yields the acetate of an isomeric ter-
penol (terpineol) ; this is converted, on hydrolysis, into a erystal-
line alcohol, melting at 69° to 70°, which is to be regarded as
a 4**)-terpen-1-ol (Baeyer’).

In order to prepare the acetate of this alcohol, a solution of
thirty grams of the tribromide (m. p. 110°) in 200 grams of
glacial acetic acid is cooled to 0° (a portion of the acetic acid
solidifies at this temperature) and is treated carefully and with
constant shaking with thirty grams of zine dust. After stand-
ing for half an hour the product is filtered and the filtrate is
diluted with water, neutralized with soda and extracted with
ether. The ethereal solution is then washed with soda, the ether
distilled off and the resultant terpenol acetate purified by distilla-
tion in vacuum ; it boils at 110° to 120° under a pressure of
17 mm. The yield amounts to eighty per cent. of the theoretical.

4*®)-Terpen-1-ol separates in the form of long needles when
the acetate is heated with an excess of alcoholic potash and the
solution is subsequently diluted with water. It crystallizes from
ether in thick prisms which melt at 69° to 70° and, like terpineol
(m. p. 35°), it has an agreeable odor of lilac. It is rather volatile, -
distills undecomposed and reacts with dilute acids like the isomeric
terpenols.

According to Baeyer,’? 4*®-terpen-1-ol is also contained in the
liquid “terpineol,” which is obtained when terpine hydrate is
heated with oxalic or phosphoric acids. When this liquid “ ter-
pineol” is boiled with acetic anhydride, an acetate is produced
from which the blue, crystalline nitrosochloride of 4*-terpen-1-ol
acetate may be readily obtained.

Liquid “terpineol” prepared by Schimmel & Co. does not
contain 4*)-terpen-1-ol.

When terpenol acetate is dropped into boiling quinoline, ter-
pinolene distills over.’

4*®)-Terpen-1-ol and its acetate readily give dipentene dihydro-
bromide when treated with a glacial acetic acid solution of hy-
drogen bromide.

1Baeyer, Ber., 27, 443.
2Baeyer, Ber., 27, 815.

270 THE TERPENES.

Terpenol dibromide,’ C,,H,,OH-Br, (4, 8-dibromoterpen-1-ol),
results by the addition of the theoretical quantity of bromine to
the alcoholic ethereal solution of terpenol ; it crystallizes in long
needles and melts at 114° to 115°.

Terpenol acetate dibromide,' C,,H,, (OCOCH,):Br,, is prepared
like the preceding compound, and forms brilliant leaflets, melting
at 103°.

If the dibromide of terpenol or its acetate be treated with
hydrobromic acid in glacial acetic acid solution, Wallach’s tri-
bromoterpane (m. p. 110°) is produced.

Nitrosochloride of 4*®)-terpen-l-ol acetate, C,,H,, (OCOCH,):
NOCI.—This very characteristic compound is prepared according
to the directions given by Thiele* for the preparation of tetra-
methyl] ethylene nitrosochloride.

Terpenol acetate is dissolved in an alcoholic solution of hydro-
chloric acid, and, when well cooled, is treated slowly with slight
excess of a concentrated solution of sodium nitrite. The liquid
immediately assumes a pure blue color, and only becomes green
when an excess of sodium nitrite is added. On the addition of
ice a heavy, blue oil separates, which solidifies to microscopic,
blue prisms. By dissolving in alcohol and precipitating with
water, brilliant blue leaflets result, which melt at 82°. It
decomposes into its components when warmed with alcohol
(Baeyer'). ;

4*®)-Terpen-l-ol also gives a blue nitrosochloride, but it has
not been thoroughly examined.

Nitrosobromide of 4**)-terpenol acetate, C,,H,,(OCOCH,)-NOBr,
crystallizes in blue needles, and melts at 81° to 82°. According
to Baeyer and Blau,’ this substance undergoes a remarkable trans-
formation when it is treated with red phosphorus and a solution
of hydrogen bromide in glacial acetic acid; the acetyl group is
replaced by a bromine atom, and the hydrobromice acid salt of a
base results, which contains a hydroxylamine group. The con-
stitution of this salt is expressed by the empirical formula,
C,,H,,Br,NHOH-HBr. It crystallizes in thin, quadratic plates,
and melts at 182° to 184°.

When this salt is dissolved in water and treated with potash or
ammonia, two molecules of hydrogen bromide are eliminated, and
a base, C,,H,,Br: NHOH, is formed. It melts at 100° to 102°.
Nitrous acid changes it into a nitroso-compound, melting at 138°
to 139°.

1 Baeyer, Ber., 27, 443.
*Thiele, Ber., 27, 455.
3Baeyer and Blan, Ber., 28, 2289.

ISOMERIC TERPINEOL. 271

It is mentioned on page 93 that when 1-bromo-4**)-terpene
is treated with sodium nitrite and hydrobromic acid, a nitroso-
bromide is obtained, which crystallizes in blue crystals and melts
at 44°. When this nitrosobromide is treated with a solution of
hydrogen bromide in acetic acid, it yields the hydrobromic acid
salt described above. Thus, the nitrosobromide of 1-bromo-
4*®)_terpene and of 4*®)-terpenol acetate yield the same product,
C,,H,,Br,NHOH-HBr.

According to Baeyer, only those substances which contain a
tertiary-tertiary double linkage are capable of forming blue nitro-
sochlorides, for example, tetramethylethylene. Consequently, there
is but one terpenol which conforms to this condition, and at the
same time contains the hydroxyl-group in such a position that
renders possible a transformation of the terpenol into dipentene
dihydrobromide. Accordingly, Baeyer assumes that terpenol (m.
p- 69° to 70°) has the following constitution :

H,
OH
H,G CH,
aie
|

Hy; CH;
A«®)-Terpen-1-ol.

Since this alcohol is readily converted into terpinolene, the
above formula supports Baeyer’s formula of terpinolene and also
agrees with the constitution which Wallach ascribes to tribromo-

372 THE TERPENES.

terpane (m. p. 110°). The following formulas illustrate these re-

lations :
CH,
OH :
H, CH, H, ‘vn
H, H, shin H, H,
(

| |

»,
H.C CH, u¢ CH,
sz A*®)-Terpen-1-ol. Terpinolene.

be 7

Sag] mf ka H, H
H, * , 1: <= ae H,
a Br

1, 4, 8-Tribromoterpane. Terpinolene di-
(m. p. 110°). bromide.

These formulas would be quite as probable if the constitution
of dipentene dihydrobromide were represented by the formula :

ISOMERIC TERPINEOL. 273

Trioxyhexahydrocymene, according to Baeyer’s nomenclature,}
1, 4, 8-trioxyterpane, C,,H,,O,, is obtained, when 4*°)-terpenol
(m. p. 69° to 70°) is dissolved in ether and oxidized with a dilute
potassium permanganate solution. It forms crystals containing
one molecule of water, and melts at 95° to 96°. It loses the
water of crystallization when heated to 50° or 60° in a vacuum ;
the anhydrous substance melts at 110° to 112°. Hydrobromic
acid converts it into Wallach’s tribromoterpane, melting at 110°
to 111° (Baeyer and Blau’),

19. ISOMERIC TERPINEOL, C,,H,,OH, MELTING AT
32° TO 33°,

In an investigation of liquid “terpineol,’ which is largely
employed in perfumes, the chemists of Schimmel & Co. succeeded
in preparing two phenylurethane derivatives ; the one melted at
112° to 113° and was found to be identical with the terpinyl
phenylurethane from terpineol, melting at 35°; the second proved
to be a new isomeric phenylurethane and melted at 85°. By hy-
drolysis of the latter, a new terpineol, melting at 32° to 33°, was
obtained.

According to more recent investigations,’ the new terpineol is
prepared as follows. A large quantity of liquid “terpineol ” is re-
peatedly fractionated under reduced pressure, two chief fractions
being obtained. Fraction 1 is optically inactive, boils at 213° to
215°, and has the sp. gr. 0.930 at 15°; fraction 2 is also optic-
ally inactive, boils at 218° to 220° and has the sp. gr. 0.940 at
15°. Both fractions congeal when exposed to continued winter
cold. The solid compounds are separated and purified by re-
peated crystallization from alcohol. Fraction 1 gives the new
terpineol, m. p. 32° to 33°, while fraction 2 yields the solid ter-
pineol, m. p. 35°. The two substances have a slightly different
odor.

_ The new terpineol crystallizes in Jong needles, melts at 32° to
33°, and boils at 90° (10 mm.) or at 209° to 210° (752 mm.) ; it
has the sp. gr. 0.923 at 15° and 0.919 at 20°, and the refractive
index, ny = 1.47470, at 20°. About seventy per cent. of ester is
formed by acetylization. When agitated with concentrated hydri-
odic acid (sp. gr. 1.96), it yields the same dipentene dihydriodide
(m. p. 77°) as is formed by similar treatment of terpineol melting
at 35°.

1Baeyer and Blau, Ber., 28, 2289. ¢
2Schimmel & Co., Semi-Annual Report, April-May, 1901, 75.

18

274 THE TERPENES.

The phenylurethane, C,,H,,0,N, is formed by treating the ter-
pineol with phenyl isocyanate ; it melts at 85°. On hydrolysis it
is reconverted into terpineol melting at 32°.

The nitrosochloride, C,,H,,OH-NOCI, is produced by the action
of amyl nitrite and hydrochloric acid on the alcohol ; it melts at
102° to 103°.

Nitrolamines are formed only with difficulty from the nitroso-
chloride ; by the action of piperidine only a small quantity of
nitrolpiperidide is obtained.

Oxy-ketone, C,H,,.O,.—When the terpineol, m. p. 32° to 33°, is
oxidized, first with potassium permanganate and then with a
chromic acid mixture, an oxy-ketone, C,H,,O,, is formed ; under
similar conditions terpineol, m. p. 35°, gives rise to the keto-lac-
tone, C,,H,,O,. This oxy-ketone boils at 140° to 145° under
19 mm. pressure, has the sp. gr. 1.023 at 20° and the refractive
index, ny = 1.47548, at 20°. Its semicarbazone crystallizes from
alcohol and melts at 195° to 196°.

When this oxy-ketone is treated with a sodium hypobromite
solution, it yields bromoform and an oxy-acid, C,H,,O, ; the latter
crystallizes from ethyl acetate, melts at about 130° and probably
consists of a number of isomeric compounds. On heating this
oxy-acid with concentrated sulphuric acid, it is converted into para-
toluic acid, melting at 176°.

The following formula is suggested by the chemists of Schimmel
& Co. as the best representation of the constitution of this terpineol :

COH

H,¢ 0H,

H, H,
‘H

H,¢ 60H,

A&)-Terpen-l-ol.

20. PINOLE, C,,H,,O.

Pinole is an unsaturated oxide, and may be obtained from
pinene or terpineol by the greatest variety of reactions. It was
discovered in the oily by-products formed in the preparation of
pinene nitrosochloride by Wallach and Otto,’ and named pinole.

1Wallach and Otto, Ann. Chem., 253, 249.

PINOLE. 275

When the oily by-products, which are formed in considerable
quantity in preparing pinene nitrosochloride, are distilled with
steam, the distillate contains a mixture of cymene, pinole, and
other substances. This crude product distills between 160° and
190°, the principal portion boiling at 180° to 186° and consist-
ing for the most part of pinole.

Soon after Wallach and Otto’s investigations, Armstrong’
showed that pinole is produced when the crystalline compound,
C,,H,,O,, obtained by Sobrero’ by exposing oil of turpentine to
the action of moist oxygen in the sunlight, is distilled with dilute
sulphuric acid. In the meantime, Wallach* prepared pinole

hydrate,
H
CFO

by the addition of the elements of water to pinole, and proved
the identity of this hydrate with the crystalline substance,
C,,H,,O,, which was first observed by Sobrero.

“Pinole may also be regenerated from pinole dibromide,
C,,H,,O-Br,, by boiling with alcoholic potash,* or by heating a
benzene solution of the dibromide with sodium wire Accord-
ing to Wallach,°® pinole may be very conveniently obtained from
the dibromide of terpineol (m. p. 35°); the resulting pinole is
very pure, hence this method is to be highly recommended for its
preparation. The details of this process are as follows.

One molecular proportion of terpineol dibromide is added to a
solution of one molecule of sodium in an excess of alcohol, and is
heated ; sodium bromide is thrown out, and, on completion of

the reaction, the product is distilled with steam. Alcohol dis-

tills over at first, and contains considerable pinole, which is
best isolated in the form of its dibromide by treating the alcoholic
solution with bromine until a yellow color is produced, and then
allowing the alcohol to evaporate. The receiver is changed when
all of the alcohol is removed, and the distillation with steam is
continued as long as the resultant oil is lighter than water. The
oil is separated, dried over potassium hydroxide, and fractionally
distilled (Wallach ° ).

1Armstrong, Chem. Ztg., 1890, 838; Journ. Chem. Soc., 1891, I., 311;
Ber., 24, 763, Ref.; Armstrong and Pope, Journ. Chem. Soc., 1891, L., 315;
Ber., 24, 764c.

2Sobrero, Ann. Chem., 80, 108.

3Wallach, Ann. Chem., 259, 309.

4Wallach and Otto, Ann. Chem., 253, 249.

5Wallach, Ann. Chem., 277, 113.

276 THE TERPENES.

PROPERTIES.—Pinole is a liquid, boiling at 183° to 184°, and
has a characteristic odor resembling that of cineole and of cam-
phor. It has a specific gravity 0.942 and refractive power,
np = 1.47145, at 20°.' It is optically inactive ; even the product
obtained from the active pinole hydrate does not rotate the plane
of polarized light.

It is readily converted into cymene on treatment with mineral
acids, hence this hydrocarbon generally results as a by-product
during the preparation of pinole :—

C,oH,,0 — H,0 = C,H,

It does not react with hydrogen sulphide, hydroxylamine,
phenylhydrazine, or benzoyl chloride.

Pinole behaves as an unsaturated compound ; when dissolved
in a dry or moist solvent, it readily unites with hydrobromic
acid, forming an additive product; this has not been obtained in
a pure condition, but it may be converted into pinole hydrate by
shaking with alkalis.

_ Pinole hydrate,
H
Cio Hig

It has been mentioned that this compound was obtained by So-
brero? in 1851 by the action of oxygen and water on turpentine
oil. Armstrong found that pinole hydrate obtained in this
manner is optically active, but that it yields inactive pinole on
warming with dilute acids; he suggested the names “ sobrerol”
for pinole hydrate and “ sobrerone”’ for pinole.

In order to convert pinole into the hydrate, it is mixed with an »
equal volume of glacial acetic acid, and the cooled solution is
saturated with hydrobromic acid; the resultant, dark-colored
liquid is poured into an excess of cold sodium hydroxide solution,
and well shaken to decompose the pinole hydrobromide. Steam
is now passed through the liquid in order to remove cymene,
which is usually found in crude pinole; the hydrate is extracted from
the alkaline solution by agitating with ether. Pinole hydrate re-
mains as acrystalline product after evaporation of theether,and may
be recrystallized from water or alcohol. It is soluble in water (one
part in thirty parts of water at 15°), and melts at 131° ( Wallach’).

According to Wagner,* pinole hydrate is to be regarded as a
" eis-compound.
1Wallach, Ann. Chem., 28/, 148.
2Sobrero, Ann. Chem., 80, 108.

3Wallach, Ann. Chem., 259, 313.
4Wagner and Slawinski, Ber., 32, 2068.

CIS-PINOLE HYDRATE DIBROMIDE. 277

The active modifications of pinole hydrate separate from alco-
holic solutions in long, tabular crystals, which possess enantiomor-
phous, hemihedral forms of the monoclinic system, and, according
to Armstrong and Pope, melt at 150°; Wallach’ found the
melting point 131°.

Inactive pinole hydrate is obtained by mixing the solutions of
equal weights of the two active modifications; the crystals sep-
arate in flat, colorless, transparent tables belonging to the ortho-
rhombic system, and melt at 131° (Armstrong and Pope).

Pinole hydrate readily loses water and is converted into pinole
when warmed with dilute sulphuric acid. According to Wallach,
it may be recrystallized unchanged from boiling acetic anhydride ;
on the other hand, Ginzberg* finds that when it is treated with
boiling acetic anhydride, it yields a diacetate, which is a viscous
liquid of agreeable odor, and has the specific gravity 1.0385
at 18°.

According to Wagner,’ pinole hydrate is to be classified as an
unsaturated y-glycol ; this view is in harmony with the fact that,
when oxidized with potassium permanganate, it yields a tetra-
hydric alcohol, cis-trans-sobrerytrite (menthane-1, 2, 6, 8-tetrol),°
C,,H,,O,. Accordingly, pinole hydrate (sobrerol) is termed 4°-
menthene-2, 8-diol, or 4'-menthene-6, 8-diol.

Cis-trans-sobrerytrite, C,,H,,O,, is very hygroscopic, and readily
forms the hydrate, C,,H,,O, + 2H,O, which separates from water
in monoclinic crystals, melts at 100° to 105°, and loses water at
120°, after which it melts at 155.5° to 160°. Oxidation with
potassium permanganate converts sobrerytrite into terpenylic acid
as the chief product, together with acetic and terebic acids.

Wallach* obtained oxydihydrocarvone, C,,H,,O(OH), whose

oxime melts at 134°, by the oxidation of pinole hydrate with
chromic acid. This result is in harmony with the view which
regards pinole hydrate as an unsaturated glycol containing one
hydroxyl-group united with a secondary and the other with a ter-
tiary carbon atom.

By a more vigorous oxidation of pinole hydrate with perman-
ganate, Wallach' obtained terpenylic acid, oxalic acid and carbon
dioxide. |

Cis-pinole hydrate dibromide* (1, 6, 2, 8 dibromodioxyhexahy-
drocymene), C,,H,,Br,(OH),, is formed by the addition of a solu-

2 .
tion of bromine in chloroform to a solution of pinole hydrate in

1Wallach, Ann. Chem., 259, 313.
2Wagner, Ber., 27, 1648; Ber., 32, 2069.
3Ginzberg, Ber., 29, 1195.

4Wallach, Ann. Chem., 291, 342.

278 THE TERPENES.

the same solvent; it melts at 131° to 132°. Sodium methylate
converts this dibromide into the anhydride of cis-pinole glycol,
C,,H,,0,.

Cis-pinole dibromide,' C,,H,,O-Br,, is one of the most character-
istic and beautiful compounds of the terpene series. It is pre-
pared by diluting pinole with twice its volume of glacial acetic
acid, and adding bromine, drop by drop, until a permanent yellow
coloration is produced. On evaporation of the solvent, pinole
dibromide separates in splendid, well defined, orthorhombic crys-
tals, which are recrystallized from ethyl acetate or a mixture of
alcohol and ether. It melts at 94°, and boils undecomposed at
143° to 144° under 11 mm. pressure. It is moderately volatile
with steam, and readily soluble in ether, alcohol, chloroform and
ethyl acetate.

Pure pinole is easily prepared by removing the bromine from
pinole dibromide by treatment with alcoholic potash or metallic
sodium.

When pinole dibromide is heated at 100° with an excess of
pure formic acid? and a small quantity of ammonium formate, it
is converted into cymene ; the same hydrocarbon is produced, to-
gether with pinole glycol diacetate, if the dibromide be boiled
with glacial acetic acid and zinc dust.* A far more important
result was obtained by Wallach *® by the reduction of the
dibromide with zine dust and glacial acetic acid in the cold;
under these conditions, crystalline terpineol (m. p. 35°) is
formed,

Hydrobromopinole dibromide, C,,H,,OBr,.—According to Wal-
lach,’ pinole dibromide combines quantitatively with one molecule
of hydrobromic acid, forming a tribromide.

A solution of fifty grams of pinole dibromide in fifty cc. of
glacial acetic acid is warmed very gently, and treated, with
shaking, with 100 cc. of a forty to fifty per cent. solution of
hydrogen bromide in glacial acetic acid. A portion of the di-
bromide separates at once in the form of leaflets. If the mixture
is now allowed to stand in a closed vessel for two days, the
crystals gradually undergo a complete change. The new com-
pound is purified by diluting the reaction-product with water,
filtering with the pump, washing with water and recrystallizing
from ethyl acetate ; the tribromide is thus obtained in brittle
needles or prisms, melting at 160°. It is also formed as a by-
product in the bromination of crude pinole.

1Wallach and Otto, Ann. Chem., 253, 253.

2Wallach, Ann. Chem., 268, 224.
3Wallach, Ann. Chem., 287, 148.

CIS-TRANS-PINOLE GLYCOL. 279

On reduction, the tribromide yields an unsaturated ketone, pino-
lone, C,,H,,O, which has an odor resembling that of amyl acetate
(Wallach’*). When a solution of this tribromide in glacial acetic
acid is digested with silver acetate, a compound, C,,H,,Br,0,,
is obtained; it crystallizes from methyl alcohol, and melts at
118° to 120° (Wallach ).

Isopinole dibromide,’ C,,H,,O-Br,, is formed by the elimination
of hydrogen bromide from hydrobromopinole dibromide by means
of quinoline in benzene, or of silver acetate in ethyl acetate ; it
separates from ether in transparent, well defined crystals, and
melts at 94°. It is an unsaturated compound, and unites with
hydrogen bromide, forming the pinole tribromide from which it
is derived. It combines with two atoms of bromine, yielding

pinole tetrabromide, C,,H,,O-Br,, which melts at 132°.

On reducing isopinole dibromide with zine and glacial acetic
acid, the ketone, pinolone, C,,H,,O (b. p. 214° to 217°), is pro-
~ duced.

Isopinole dibromide and pinole tribromide are converted into
inactive carvone by means of a hot, ten per cent. solution of potas-
sium hydroxide; sodium methylate, however, gives rise to the
methyl ether of carveol or carvacrol.

Cis-pinole glycol, C,,H,,O(OH),, may be prepared directly from
pinole dibromide by the replacement of the bromine atoms with
hydroxyl-groups. This can be effected by boiling seven grams
of the dibromide with five grams of freshly precipitated lead
hydroxide and 100 cc. of water, in a reflux apparatus, for sev-
eral hours. The reaction-product is cooled, the lead bromide
is filtered off, and the filtrate extracted with chloroform, or the
aqueous solution may be evaporated at a relatively low tempera-

_ture until crystallization commences (Wallach and Friistiick’).

It may also be obtained by the hydrolysis of cis-pinole glycol
diacetate.

It separates from its solutions in chloroform by the addition of
petroleum ether, and crystallizes from water in hard crystals,
which melt at 125°. It is changed into cis-pinole glycol diacetate
by boiling with acetic anhydride. Terpenylic acid is formed by
oxidizing pinole glycol with potassium permanganate (Wallach).

Cis-trans-pinole glycol, C,,H,,O(OH),.—According to Wagner,’
pinole is oxidized by a very dilute solution of potassium perman-
ganate to a glycol, isomeric with that obtained from pinole dibro-

1Wallach, Ber., 28, 2708.

2Wallach, Ann. Chem., 306, 267.

3Wallach and Friistiick, Ann. Chem., 268, 223.

4Wagner, Ber., 27, 1644; Wagner and Slawinski, Ber., 32, 2067.

280 THE TERPENES.

mide. It appears to be a dimorphous compound, crystallizing
from ether and ethy] acetate in orthorhombic pyramids, which melt
at 126° to 127°, and from water in monoclinic tablets, which
melt at 128° to 129°. Acetic anhydride converts this glycol into
a diacetate, which boils at 154° to 155° (10.5 mm.), or at 166°
to 167° (17 mm.); after standing during a long time (Wagner
reports two years), it solidifies, and melts at 37° to 38°. (Com-
pare with Wallach.')

According to Wagner, the glycol obtained from pinole dibro-
mide is to be regarded as the cis-modification, and that derived by
the oxidation of pinole as the cis-trans-derivative.

d-Cis-trans-pinole glycol is the dextrorotatory modification of the
above described glycol. It melts at 73° to 74.5°. (See under
cis-pinole glycol-2-chlorhydrin, page 282.)

Cis-pinole glycol diacetate, C,,H,,O0(OCOCH,),, is produced by
the treatment of pinole dibromide with silver or lead acetate
( Wallach’).

Twenty-five grams of pulverized pinole dibromide are heated
with thirty grams of lead acetate in glacial acetic acid solution in
an oil-bath at 150° ; the reaction commences at a moderate temper-
ature, and is complete in a short time. The resultant lead bromide
is filtered off, acetic acid is removed from the filtrate by distilla-
tion, and the residue is submitted to distillation in vacuum. The
diacetate passes over as an oil, which boils at 155° under 20 mm.
pressure, or at 127° under 13 mm., and soon solidifies. It may
be recrystallized from water, although when its aqueous solution
is boiled it is changed into pinole glycol. It melts at 97° to 98°.

The diacetate is also formed, together with cymene, when
pinole dibromide is boiled with zinc dust and glacial acetic acid.*

Cis-pinole glycol dipropionate,’ C,,H,,O(OCOC,H,),, results on
heating pinole dibromide with propionic acid and silver propionate,
or by warming the glycol with propionic anhydride. It is in-
soluble in water, soluble in alcohol, and melts at 106°.

Cis-pinole glycol diethyl ether,* C,,H,,O (OC,H,),, results, to-
gether with pinole, by the action of alcoholic potash on pinole di-
bromide. It forms hard needles when recrystallized from ether,
and melts at 52° to 53°.

Anhydride of cis-pinole glycol’ (cis-pinole oxide), C,,H,,O,, is
produced by the action of sodium methylate on the dibromide of

tWallach, Ber., 28, 2708.

2Wallach, Ann. Chem., 259, 311; 268, 222.
3Wallach, Ann. Chem., 281, 149.

4Wallach and Otto, Ann. Chem., 253, 260.
5Wallach and Guericke, Ann. Chem., 291, 342.

a

I |

CIS-PINOLE. 281

cis-pinole hydrate. It is an oil, which boils at 206° to 207°, and
at 82° under a pressure of 12 mm.; it has the specific gravity
1.0335 and the refractive index, np, = 1.4588, at 20°. It isa
saturated compound, and hydrolysis converts it into cis-pinole
glycol (m. p. 124°); it is, therefore, a true anhydride of the latter
compound.

Cis-pinole glycol anhydride is also described by Wagner ' under
the name cis-pinole oxide ; he obtained it as one of the products
formed during the action of hypochlorous acid on levo-pinene and
subsequent treatment with potassium hydroxide. It boils at 206°
to 208°, is optically inactive, or in some cases feebly levorotatory,
and is immediately converted into the corresponding inactive cis-
pinole glycol (m. p. 124°) by agitation with two per cent. sul-
phuric acid; the latter yields the diacetate (m. p. 97°), and on
oxidation is converted into terpenylic acid.

The anhydride is also produced by the action of potassium hy-
droxide at the ordinary temperature on cis-pinole glycol-1-chlor-
hydrin.?

Cis-pinole glycol-1-chlorhydrin,? C,,H,,OCI(OH), is formed by the
action of hypochlorous acid on pinole; it crystallizes from petro-
leum ether in long needles, melts at 52° to 54° and is readily
soluble in the usual organic solvents and water. Its aqueous solu-
tion soon gives an acid reaction. Potassium hydroxide converts
it into the anhydride of cis-pinole glycol. Oxidation with chro-
mic acid at 0° converts this chlorhydrin into a chloroketone, C,,H,,-
ClO,, which crystallizes in long needles, melts at 74° to 75.5°,
and yields a hydrazone, melting at 107° to 108°.

Cis-pinole glycol-2-chlorhydrin, C,,H,,OCI(OH), is another com-
pound, which Wagner obtained by treating turpentine oil with

- hypochlorous acid and subsequent treatment of the product with

potash. It separates from acetic ether in large, transparent,
rhombic crystals. The chlorhydrin prepared from French tur-
pentine oil (levo-pinene) melts at 131° to 132°, and is dextro-
rotatory, [a], = + 88° 23’; that obtained from dextro-pinene
melts at the same temperature, but is levorotatory, [¢])=—
87°39’. When equal weights of the two active derivatives are
crystallized from petroleum ether, the inactive modification results,
which melts at 104° to 105°.

It is not readily acted upon by aqueous alkali, but after long-
continued boiling it is converted into cis-pinole glycol (m. p.
123° to 124°).

1Wagner and Slawinski, Ber., 32, 2065. “ce hae
2A, Ginzberg, Journ. Russ. Chem. Soc., 30, 681; Wagner and Slawinski,
Ber., 32, 2073.

282 THE TERPENES.

When this chlorhydrin is heated with zinc dust and alcohol on
the water-bath for three weeks, it yields pinole as the only prod-
uct ; when this pinole is oxidized in the cold with dilute per-
manganate, it yields a dextrorotatory glycol which Wagner
terms d-cis-trans-pinole glycol, C,,H,,O,. This compound melts
at 73° to 74.5°, is dextrorotatory, [a],—= + 8° 20’ (one deci-
meter tube, alcoholic solution), and is readily soluble in ether and
ethyl acetate ; on oxidation with permanganate, it yields acetic,
terpenylic, and terebic acids. The pinole from which it is de-
rived is probably the optically active modification of ordinary
pinole, although it combines with two atoms of bromine, yielding
the inactive pinole dibromide (m. p. 94°).
Cis-menthane-1, 2-dichlor-6, 8-diol, C,,H,,O,Cl,, is also formed
during the reaction of hypochlorous acid upon pinene; it
crystallizes from boiling ether in small crystals, and melts at
136° to 137°. In contrast to the monochlorhydrin (m, p. 131°
to 132°), this dichlorhydrin readily loses its chlorine atoms when
warmed with aqueous potash, and is converted into the anhy-
dride of cis-pinole glycol. It is also acted upon by cold, aqueous
potash solution, yielding the anhydride of cis-pinole glycol and
a new crystalline, saturated chlorhydrin, which, however, has not
yet been carefully investigated ; the latter compound is further
formed in small quantity by the action of hypochlorous acid on
pinene.

When the dichlorhydrin is treated with zine dust and alcohol,
it yields limonene (?) and pinole hydrate (m. p. 129° to 129.5°).

Cis-sobrerytrite (menthane-1, 2, 6, 8-tetrol), C,,H,,O,, is formed
during the action of hypochlorous acid upon pinene. It is spar-
ingly soluble in ether, but dissolves readily in alcohol or water ;
it has a sweet taste, is optically inactive, and melts at 193° to
194°. Potassium permanganate oxidizes it, yielding terpenylic
and acetic acids.

This compound is also produced when cis-pinole glycol is treated
with a glacial acetic acid solution of hydrogen bromide, and the re-
sulting bromine derivative is treated with aqueous sodium hydrox-
ide. It is isomeric with the cis-trans-sobrerytrite obtained in the
oxidation of inactive pinole hydrate ; both isomerides are optic-
ally inactive, but are characterized by different melting points, and
by the fact that the cis-trans-derivative easily forms a hydrate,
C,,H,,0, + 2H,O, while the cis-modification does not.

Nopinole glycol, C,,H,,O,, a product of the action of hypochlo-
rous acid on pinene, melts at 126° to 127° and is a derivative of
an isomeride of pinene, while the preceding compounds may be
regarded as derivatives of ordinary pinene. Its diacetate is an

PINOLE ISONITROSOCHLORIDE. 283

oil. Oxidation converts it into formic acid and a non-volatile,
syrupy acid, no acetic or terpenylic acid being produced.

Pinole bisnitrosochloride,' (C,,H,,O),N,O,CL,, is formed when six
ec. of fuming hydrochloric acid are very gradually added to a
well cooled mixture of five cc. of pinole, seven cc. of amyl nitrite,
and ten ce. of glacial acetic acid; the liquid assumes a deep blue
color, and the bisnitroso-compound separates slowly as a white,
crystalline precipitate. It is filtered and purified by washing with
methyl alcohol and ether. It melts at 103° when heated slowly,
but on rapid heating the melting point of 116° to 120° is
found.

It is almost insoluble in methyl alcohol, but dissolves in chloro-
form or benzene, the solution having a blue color at the ordinary
temperature, becoming darker on heating. A dry solution of this
chloride in chloroform is colorless at —12°, becoming blue as the
temperature rises, and is again colorless on strong cooling. The
pure bisnitrosochloride forms a colorless solution at low tempera-
tures, but on dissociation with rise in temperature, yields the
mono-molecular derivative, C,,H,,NOCI, which dissolves in chloro-
form forming a blue colored solution. Thesame assumption may
be made with many other colorless nitrosochlorides which dis-
solve, forming blue colored solutions.

When pinole bisnitrosochloride is allowed to stand for a long
time, it is partially converted into an isomeride, pinole isonitroso-
chloride, which is soluble in methyl alcohol.

Pinole isonitrosochloride, ? C,,H,,O - NOCI, is produced, as above
mentioned, by the slow spontaneous change of the dimolecular
eompound. Thus, if an old specimen of the bisnitrosochloride is
treated with methyl alcohol, the iso-compound is dissolved, and
_is obtained in splendid crystals.

It is more readily prepared by saturating a solution of the bis-
nitrosochloride in ethyl acetate with hydrogen chloride ; on
evaporation of the solvent, the isonitrosochloride separates in well
defined crystals, which dissolve in acetic ether forming a colorless
solution, and crystallize in colorless, transparent prisms. It
melts at 131°, becoming brown and decomposing at 150°; it is a
monomolecular compound. It reacts with bases (aniline, piper-
idine, f-naphthylamine, etc.), forming nitrolamines which are
identical with those obtained from pinole bisnitrosochloride (see

below).

1Wallach and Otto, Ann. Chem., 253, 260; Wallach and Sieverts, Ann.
Chem., 306, 278.
2Wallach and Sieverts, Ann. Chem., 306, 279.

284 THE TERPENES.

When the bisnitrosochloride or the isonitrosochloride is heated
with alcohols, the chlorine atom is replaced by the oxy-alkyl
group, yielding the following compounds.

Methoxyl-derivative,

NOH
HZ
\OocH,

forms well defined crystals, and melts at 138°.
Ethoxyl-derivative,
JNOH

CoH
OC,H;

crystallizes in prisms, and melts at 100°.

Benzoyl] chloride reacts with the pinole nitrosochlorides forming
benzoyl-derivatives.

When the nitrosochlorides are treated with sodium ethylate, a
white, amorphous compound is formed.

Ammonia or organic bases readily convert pinole bisnitroso-
chloride into the following nitrolamines, all of which were pre-
pared by Wallach and Otto.’ Since the same compounds are also
derived from pinole isonitrosochloride, it is probable that, in con-
tact with bases, the bisnitrosochloride is at first changed into the
monomolecular isonitrosochloride, which then gives rise to the
nitrolamines. It is also probable that a similar change takes
place in all cases in which bis-nitrosochlorides are converted into
nitrolamines, since, according to the observations so far reported,
the nitrolamines are always monomolecular compounds ( Wallach’).

Pinole nitrolamine, C,,H,,O-NO-NH.,, is produced when pinole
nitrosochloride is treated with excess of alcoholic ammonia; the
mixture becomes warm, ammonium chloride is thrown out and
filtered off, and pinole nitrolamine hydrochloride separates from
the cold filtrate, while the free base remains dissolved in the
alcohol. Wallach and Otto did not isolate the free amine, but
analyzed its hydrochloric acid salt, C,,H,,N,O,-HCl, which ecrys-
tallizes well from water or dilute alcohol.

Pinole nitrolpiperidide, C,,H,,O-NO-NC,H,,, is formed by
gently warming one molecule by weight of the nitrosochloride
with a solution of two molecules of piperidine in alcohol ; after

diluting the reaction-product with water the base separates as an ~

oil, which quickly solidifies, and, on recrystallization from alcohol,
melts at 154°.

1 Wallach and Otto, Ann. Chem., 253, 260.
2 Wallach and Sieverts, Ann. Chem., 306, 281.

eee

EUDESMOLE. 285

The hydrochloride is precipitated from an ethereal solution of
the base, and is very readily soluble in water.

Pinole nitrolbenzylamine, C,,H,,O-NO.NHCH,C,H., crystallizes
from ether in well defined, transparent prisms, which become
opaque on standing in the air; it melts at 135° to 136°. It
separates from alcoholic solutions with one molecule of alcohol of
crystallization.

Pinole nitrolanilide, C,,H,,O.NO-NHC,H,, is easily soluble in
alcohol and ether, and forms brilliant plates, melting at 174° to
175°. When the base is dissolved in warm hydrochloric acid,
the hydrochloride results and crystallizes from the cold solution ;
this salt loses a part of its hydrogen chloride on continued ex-
posure to the air.

Pinole nitrol- $-naphthylamide, C,,H,,O. NO.NHC,,H,.—This
base is only sparingly soluble in warm alcohol, but is readily
purified by recrystallization from alcoholic ether, and melts at
194° to 195°; solutions of the free amine and its salts are highly
fluorescent. This compound is isomeric with quinine.

Oxidation of Pinole.

According to Wagner,’ the first product of the oxidation of
pinole with a one per cent. solution of potassium permanganate at
about 0° is cis-trans-pinole glycol; if a more concentrated solu-
tion be used, there are formed, in addition to pinole glycol, ter-
penylic acid and a trace of terebic acid.

Wallach * showed that pinole is oxidized by warm, relatively
concentrated potassium permanganate solution, as well as by
dilute nitric acid, yielding terebic acid (m. p. 175° to 176°), to-
gether with oxalic acid and carbonic acid. On the other hand,
pinole hydrate and pinole glycol give terpenylic acid, when oxi-
dized with permanganate.

21. EUDESMOLE, C,,H,,0.

A compound, C,,H,,O, which apparently contains neither a
hydroxyl- nor a ketone group, was discovered by Smith® in the
oil of Hucalyptus piperita. Although a very complete investiga-
tion of this compound has not yet been made, it seems probable

1Wagner, Ber., 27, 1645.

2Wallach and Otto, Ann. Chem., 253, 256; Wallach, Ann. Chem., 259,
317; Ber., 28, 2708.

3Baker and Smith, Journ. and Proce. of the Royal Soc. of N. 8S. Wales;
32, 104; 33, 86; Semi-Annual Report of Schimmel & Co., April, 1900, 27.

286 THE TERPENES.

that the substance is an unsaturated oxide, and is called eu-
desmole.

Its presence has been determined in the oils of Hucalyptus pip-
erita, goniocalyx, camphora, smithti, macrorrhyncha, stricta and
eleeophora.

Eudesmole is best obtained by the fractional distillation of the
oil of Eucalyptus macrorrhyncha; the fractions boiling up to
190°, which contain a trace of phellandrene and cineole, are re-
moved, and, on cooling, the crude eudesmole. separates from the
residue as a butter-like, crystalline mass. It is purified by
pressing on porous plates and repeatedly crystallizing from dilute
alcohol.

PROPERTIES.—Eudesmole crystallizes from dilute alcohol in
white, very fine needles, which melt at 79° to 80° ; it boils at 270°
to 272°. It is insoluble in water and aqueous alkali solutions, but
dissolves readily in the usual organic solvents ; it sublimes easily,
and is optically inactive. It fails to give the characteristic reac-
tions of alcohols and ketones, and for this reason alone it is clas-
sified in this book as an oxide. Itis an unsaturated compound.

Eudesmole dibromide, C,,H,,O-Br,, is formed on adding one
molecular proportion of bromine to a cold solution of eudesmole
in glacial acetic acid; the dibromide separates in a hard, plastic
mass, which can not be obtained ina crystalline condition. It
melts at 55° to 56°.

Dinitroeudesmole, C,,H,,(NO,),O, is produced by the action of
cold, concentrated nitric acid on eudesmole. It melts at 90°, is
soluble in alcohol, ether and acetone, but is not crystalline.

When eudesmole is oxidized with dilute nitric acid, an acid,
melting at 165° to 168°, is formed ; it is possibly inactive cam-
phoronic acid.

a

oa

C. SUBSTANCES WITHOUT AN ETHYLENE LINKAGE.

(KETONES, C,,H,,0, ALCOHOLS, C,,H,,OH, AND
C,,H,,(OH),, OXIDES, C,,H,,.O, etc.).

_1, TETRAHYDROCARVONE (CARVOMENTHONE), C_,H,,0.
Tetrahydrocarvone has the constitutional formula :

H,C CH,

It is known in two optically active modifications which are ob-
tained, together with optically active tetrahydrocarveol and tetra-
hydrocarvylamine, when phellandrene nitrosite is reduced with
sodium and alcohol.’ Inactive tetrahydrocarvone is formed when
equal portions of dextro- and levo-tetrahydrocarvone are united.
The inactive modification is also obtained as a product of the oxi-
dation of tetrahydrocarveol (carvomenthol),C,,H,,OH. It should
be mentioned here that tetrahydrocarveol may be obtained by three
different methods : from solid terpineol (m. p. 35°) (Wallach), from

- earvotanacetone (Semmler, Wallach), and from carvone (Baeyer).

Terpineol. Thujone. Carvone.
Cro OH ~ C,)H,,0
Trioxyhexahydrocymene, Carvotanacetone, Dihydrocarveol,
wH,,(OH )s CyoH yO CyoH),0
Carvenone, Dihydrocarveol acetate hydriodide,
CioHi¢9 C,oH,,(OCOCH; ) HI
Tetrah aeigrsea (Carvomenthol),
10419
Tetrahydrocarvyone,
Cio H,0.

1Wallach and Herbig, Ann. Chem., 287, 371.
287

288 THE TERPENES.

Only inactive tetrahydrocarvone can be prepared from terpi-
neol and carvotanacetone, but the method proposed by Baeyer by
means of carvone renders possible the formation of optically ac-
tive modifications."

In order to prepare it, Baeyer? oxidizes tetrahydrocarveol with
Beckmann’s chromic acid mixture, whilst Wallach* recommends
a solution of chromic anhydride in glacial acetic acid as the oxidiz-
ing agent. The resultant tetrahydrocarvone is distilled in a cur-
rent of steam, and is purified by conversion into its acid sodium
sulphite compound (Baeyer), or into its oxime or semicarbazone *
which may be reconverted quantitatively into pure tetrahydro-
carvone by warming with dilute sulphuric acid.

PROPERTIES.—Tetrahydrocarvone is an oil, which smells more
like carvone than menthone. According to Baeyer, it boils at 222°
to 223° (corr.). According to Wallach, it boils at 220° to 221°,
has a specific gravity of 0.904 at 20°, and a specific refractive
power, np = 1.45539.

It is relatively stable towards permanganate. Its acid sulphite
compound is decomposed into its components by cold water. In
a moist ethereal solution carvomenthone is reduced by sodium to
the corresponding alcohol, tetrahydrocarveol.

According to Baeyer and Oehler,’ when tetrahydrocarvone is
gently oxidized at 40° with potassium permanganate, 5-isopropyl-
heptan 2-onic acid (m. p. 40°) is formed :—

CH,CO - CH, - CH, - CH—CH,—COOH.
H(CHs),

By more vigorous action with hot permanganate solution, this acid
is converted into isopropyl succinic acid, which melts at 114° to
115°. The oxime of isopropyl heptanonic acid melts at 75° to
78°, and is formed, together with bisnitrosotetrahydrocarvone,®
C,,H,,N,O,, melting at 119° with decomposition, by the action of
amyl nitrite and hydrochloric acid on tetrahydrocarvone.

When bisnitrosotetrahydrocarvone is treated with ethereal hy-
drogen chloride, it yields tetrahydrocarvone bisnitrosylic acid, C,,-
H,,N,O,, and a chlorinated ketone, C,,H,,ClO; the bisnitrosylie
acid crystallizes in leaflets and melts at "32° ; its oxime is also
formed in the same reaction and melts at 75° to 77°.

1Baeyer, Ber., 28, 1586.

2Baeyer, Ber., 26, 822.
3Wallach, Ann. Chem., 277, 133.
Wallach, Ber., 28, 1955.
5Baeyer and Oehler, Ber., 29, 27.
6Baeyer, Ber., 28, 1588; 29, 33.

ie

eee

a-ISOTETRAHYDROCARVOXIME. 289

When the chlorinated ketone, C,,H,,ClO, above mentioned, is
treated with sodium acetate and acetic acid for the elimination of
hydrochloric acid, a ketone, C,,H,,O, is produced, which is called
terpenone.

Terpenone,' C,,H,,O, is purified by steam distillation ; it boils at
233° to 235° and has an odor somewhat similar to that of car-
vone. It forms a semicarbazone, which crystallizes from dilute
aleohol in prisms or needles containing water of crystallization,
and melts at 222° to 223°.

According to Semmler,’ when terpenone, C,,H,,O, is oxidized
with potassium permanganate, it yields a liquid acid, C,H,,O,,
which on further oxidation forms isopropyl succinic acid (m. p.
112°). From its behavior towards oxidizing agents, Semmler
regards terpenone as the pseudo-ketone corresponding to carvotan-
acetone ; the latter is regarded as an ortho-ketone.

Tetrahydrocarvoxime, C,,H,,.NOH, is prepared from tetrahydro-
carvone in the same manner as carvoxime from carvone. The
crude ketone obtained by the oxidation of tetrahydrocarveol is
employed, and in order to insure a successful result it is important
that this oxidation product should not contain any considerable
quantities of tetrahydrocarveol ; if, however, a large amount of
the latter compound is present, the crude product must be again
treated with chromic acid.

Tetrahydrocarvoxime may be recrystallized from dilute alcohol
or better from petroleum ether. The inactive modification melts
at 105° (Wallach). Optically active tetrahydrocarvoxime crys-
tallizes from dilute alcohol in prisms resembling those of calcite,
melts at 97° to 99°, and possesses the opposite rotatory power to
that of the phellandrene from which it is prepared (Wallach and
Herbig).

When tetrahydrocarvoxime is gently heated with sulphuric acid
containing some water, it yields an aminodecoic acid, C,,H,,O,N,
which separates from water in small crystals, melting at 201° to
202°; nitrous acid converts it into decenoic acid, C,,H,,O,, which
boils at 257° to 260°, has a sp. gr. 0.936, the refractive index, np =
1.4554, at 20°, and a molecular refraction, M = 49.21 (Wallach °).

a-Isotetrahydrocarvoxime, C,,H,,NO, is obtained by treating a
chloroform solution of tetrahydrocarvoxime with one molecule by
weight of phosphorus pentachloride; when the resultant, ener-
getic reaction is complete, the solution is repeatedly shaken with
water, and on evaporation of the chloroform a syrup remains,

1Baeyer and Oehler, Ber., 29, 35.

2Semmler, Ber., 33, 2459.
3Wallach, Ann. Chem., 312, 171.

19

290 THE TERPENES.

which solidifies to a crystalline mass. This is dissolved, without
regeneration of tetrahydrocarvone, by warming for a short time
with dilute sulphuric acid, the oily impurities are separated by
filtering through a wet filter paper, and the u-isoxime is precipi-
tated by neutralizing the filtrate with ammonia. Additional
amounts may be obtained by extracting the aqueous solution with
ether (Wallach). It is very soluble in all solvents, is recrystal-
lized from petroleum ether, and melts at 51° to 52°. It is con-
verted into the f-isoxime by heating above its melting point (to
about 100° to 110°).

f-Isotetrahydrocarvoxime, C,,H,,NO, like the a-isoxime, is
stable towards warm, dilute sulphuric acid, but is distinguished
from the a-compound by being less soluble in all solvents, and by
its great power of crystallization. It melts at 104°.

i-Amido-2-hexahydrocymene (tetrahydrocarvylamine),C,,H,,.NH.,
is formed when tetrahydrocarvoxime is reduced with sodium and
alcohol.

a-Semicarbazone’ and f§-semicarbazone” of inactive tetrahydro-
carvone are formed simultaneously ; the former melts at 174°,
and the latter at 135° to 140°. The semicarbazone of optically
active tetrahydrocarvone forms hard needles, which melt at 185° to
187° (Wallach and Herbig*); according to Baeyer,* it melts at
194° to 195°.

Oxymethylene tetrahydrocarvone, C,,H,,O = CH(OH), is pro-
duced by the action of amyl formate and sodium on an ethereal
solution of carone. It is optically active (Baeyer *).

Condensation-product of tetrahydrocarvone and benzaldehyde,’
C,,H,,0,.— A mixture of twenty grams of tetrahydrocarvone and
fourteen grams of benzaldehyde are well cooled, and saturated
with dry hydrochloric acid ; the product is allowed to stand for a
day, is then washed with soda and ligroine, and the resultant
solid compound is dissolved in chloroform. It is further purified
by distilling off the chloroform, recrystallizing the residue from
ethyl acetate, and then digesting the product for a short time with
a solution of sodium ethylate in order to remove the last traces
of hydrochloric acid. The pure compound separates from acetic
ether in colorless crystals, and melts at 175°. It is almost in-
soluble in alcohol and ligroine, sparingly soluble in ethyl acetate,
and readily soluble in chloroform.

1Wallach, Ann. Chem., 286, 107.

2Wallach, Ber., 28, 1955.

3Wallach and Herbig, Ann. Chem., 287, 371.
4Baeyer, Ber., 28, 1586.

5Wallach, Ann. Chem., 395, 266.

—

PGE

air Bape Ca Fk Veale ag ta, pS ee 8 OE TE Oe MN AG ty rt

TETRAHYDROCARVEOL. 291

It is formed according to the equation :

C,,H,.0 + 20,H,CHO = H,0 + C,,H,,0,.

It does not unite with the elements of hydrogen chloride; on
reduction, it seems to combine with two atoms of hydrogen.

1, 8-Oxybromotetrahydrocarvone,' C,,H,,Br(OH)O, is produced
in the form of its sodium salt when Wallach’s dihydrocarvone
dibromide (1, 8-dibromotetrahydrocarvone), C,,H,,BrO- HBr, is
diluted with ether and is agitated with sodium hydroxide solution
(sp. gr. 1.23) for about one hour; the sodium derivative is de-
composed with dilute sulphuric acid, and the oxybromotetrahy-
drocarvone is rapidly filtered. It is recrystallized from dry ether
or a mixture of amylene and petroleum ether, and is obtained in
large prisms, melting at 69° to 72°. It is optically active, is
readily soluble in most solvents, and is somewhat unstable, being
decomposed both by acids and alkalis.

When recrystallized from methyl alcohol, a small quantity of
an isomeric substance, melting at 136° to 138°, is obtained.

An optically active oxycarone, C,,H,,O, is formed by treating
oxybromotetrahydrocarvone with methy] alcoholic potash.

The ketone, C,,H,,O, described by Marsh and Hartridge’
under the name carvanone, is probably identical with tetrahydro-
carvone.

For the action of Caro’s reagent upon tetrahydrocarvone, refer-
ence must be made to the original publication.’

2. TETRAHYDROCARVEOL (CARVOMENTHOL), C,,H,,OH.

Tetrahydrocarveol was first described by Baeyer,* and shortly
afterward by Wallach.’ Baeyer obtained it from dihydrocarveol,

~ the aleohol formed by the reduction of carvone. Dihydrocarveol

acetate combines with hydriodic acid in a glacial acetic acid solu-
tion; when the resultant hydriodide is washed with water, ex-
tracted with ether, and reduced with zine duct and acetic acid at
a temperature not exceeding 25°, tetrahydrocarveol acetate is
formed, which, on careful saponification with alcoholic potash,
yields tetrahydrocarveol. This is purified by digesting with
permanganate, which is added until its color remains permanent
for a short time ; nevertheless, a product purified in such a man-
ner contains impurities, which decompose by distillation.®

1Baeyer and Baumgirtel, Ber., 31, 3208.

2Marsh and Hartridge, Journ. Chem. Soc., 73, 857.

3Baeyer and Villiger, Ber., 32, 3625.

4Baeyer, Ber., 26, 822.

5Wallach, Ann. Chem., 277, 130.

6 Baeyer, Ber., 26, 2558.

292 THE TERPENES.

Wallach’s method of preparation of tetrahydrocarveol is more
convenient. He employs carvenone, C,,H,,O, which is obtained,
together with cymene, when trioxyhexahydrocymene (formed by
oxidation of terpineol, melting at 35°) is heated with dilute sul-
phuric acid. Twenty grams of carvenone are dissolved in 100
grams of absolute alcohol, and gradually treated with twenty
grams of metallic sodium. The reaction-product is distilled
with steam, the oil is separated, dried with potash, and purified
by repeated fractional distillations. It boils at 218° to 220°.

The product obtained by Semmler’ in the reduction of carvo-
tanacetone, .C,,H,,O, with alcohol and sodium is identical with
tetrahydrocarveol. This compound, designated by Semmler as.
tetrahydrocarvotunacetone, boils at 219° to 220°, has the sp. gr.
0.9014, and refractive index, ny = 1.4685. (Compare with Wal-
lach.?

Optically active tetrahydrocarveol is also formed in the reduc-
tion of phellandrene nitrosite with sodium and alcohol? (see tetra-
hydrocarvone).

Wallach * prepares pure tetrahydrocarvesl by reduction of pure
tetrahydrocarvone with sodium and alcohol ; it boils at 220°, has
the specific gravity of 0.900 and refractive power, np = 1, 46246,
at 23°.

The odor of tetrahydrocarveol is very similar to that of tsruine
eol and of dihydrocarveol. It is a very thick liquid at ordinary
temperature, and becomes hard, brittle and vitreous, but not crys-
talline, on cooling with a mixture of solid carbonic anhydride and
ether. It is perceptibly soluble in water, and is capable of unit-
ing with it. Chromic anhydride converts it into tetrahydrocarvone.

Carvomenthene, C,,H,,, is prepared by warming tetrahydro-
carveol with acid potassium sulphate; it boils at 175° to 176°
(Wallach). It is also formed when the bromide, C,,H,,Br, ob-
tained by the action of warm, concentrated hydrobromic acid on
tetrahydrocarveol, is heated with quinoline (Baeyer, and Konda-
koff and Lutschinin).

Tetrahydrocarvyl phenylurethane, C,,H,,O-CO-NHC,H,, is pro-
duced when pure tetrahydrocarveol is allowed to stand for one
day with one molecular proportion of carbanile; the reaction-
product is washed with petroleum ether, and crystallized from a
mixture of ether and petroleum ether ; it separates in needles, and

1Semmler, Ber., 27, 895.

2Wallach, Ber., 28, 1955.

3Wallach and Herbig, Ann. Chem., 287, 371.

4Wallach, Ann. Chem., 277, 130; Kondakoff and Lutschinin, Journ. pr.
Chem., 60 [I1.], 257.

TETRAHYDROEUCARVONE. 293

melts at 74° to 75°. It dissolves very readily in alcohol and
ether (Wallach’).

Tetrahydrocarvyl acetate (carvomenthyl acetate’), C,,H,,O-CO-
CH,, boils at 235° to 238° under a pressure of 761 mm., and at
105° to 107° at 11 mm. It is a colorless, fairly mobile liquid
having a faint odor of cherries ; it has the specific gravity 0.9280
at 22°/4°, a refractive index, n, = 1.45079, a molecular refrac-
tion, M= 57.42, and a specific rotatory power, [a],= + 4°7’.

Tetrahydrocarvyl chloride,’ C,,H,,Cl, is a colorless liquid hav-
ing the odor of menthy] chloride ; it boils at 90° to 95° (15 mm.),
and at 82° to 85° (11 mm.). It is optically inactive, has a
specific gravity 0.9450 at 21°/4°, a refractive index, np = 1.46534,
at 21°, and a molecular refraction, M = 50.48.

Tetrahydrocarvyl bromide,” C,,H,,Br, is colorless, boils at 95°
to 99° (10 mm.), has a specific gravity 1.1870 at 21°, a refrac-
tive index, ny = 1.49060, at 21°/21°, and a molecular refraction,
M= 53.39.

The properties of carvomenthyl chloride and bromide are
almost identical with those of carvomenthene hydrochloride and
hydrobromide.

When carvomenthyl chloride or bromide is treated with moist
silver oxide, tertiary carvomenthol is formed, together with a
small quantity of a compound, C,,H,,O,, which crystallizes in
slender needles, and melts at 101° to 102°.

“Carvanol,”* C,,H,O, a compound obtained by the reduction
of “carvenol,”’ C,,H,,O, is probably identical with tetrahydrocar-
veol; on oxidation “carvanol” is converted into “ carvanone”’
(tetrahydrocarvone), C,,H,,O.

8. TETRAHYDROEUCARVONE, C,,H,,O.

When dihydroeucarvoxime hydriodide, C,,H,,NOH'HI, is re-
duced with zine dust and an alcoholic solution of hydrogen chloride
at 0°, it is converted into the ketone, tetrahydroeucarvone.* It
is freed from unsaturated compounds by treatment with potassium
permanganate. The pure ketone boils at 108° to 115° under a
pressure of 20 mm.

It yields a liquid oxime, C,,H,, NOH.

Its semicarbazone, C,,H,, = N-NH-CO-NH,, crystallizes from
ethyl acetate in fine needles, melts at 191°, and is sparingly
soluble in ether and ethyl] acetate.

1Wallach, Ann. Chem., 277, 130.

2Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257.

3Marsh and Hartridge, Journ. Chem. Soc., 73, 857.
4Baeyer and Villiger, Ber., 31, 2067.

294 THE TERPENES.

Tetrahydroeucarvone is not acted upon by amyl nitrite and
hydrochloric acid.

When it is oxidized with the theoretical quantity of a cold, four
per cent. potassium permanganate solution, it is partially converted
into the ketonic acid, C,,H,,O,; this acid is purified by regenera-
tion from its semicarbazone. It is a liquid acid, and is probably
a methyl ketone. Its semicarbazone, C,,H,,0O, = N-NH-CO-NH,,
is sparingly soluble, but crystallizes from warm ethyl acetate in
long needles, melting at 191°. Its oxime, C,,H,,O, = NOH,
crystallizes in transparent prisms, which melt at 101° to 102°.

Gem-dimethyl adipic acid, C,H,,O,, is the chief product of the
oxidation of tetrahydroeucarvone with cold permanganate ; it
crystallizes from petroleum ether in prisms, and melts at 87° to 88°.

When tetrahydroeucarvone is oxidized with a warm, fairly
concentrated solution of permanganate, it gives rise to a mixture
of acetic, oxalic, dimethyl malonic, and gem-dimethyl succinic
acids.

4, THUJAMENTHONE, C,,H,,O.

On heating thujone at 280°, it is converted into carvotanace-
tone ; this differs from isothujone, and yields carvomenthol (tetra-
hydrocarveol) by reduction. When thujone is treated with dilute
sulphurie acid, it is converted into isothujone ; on reduction, this
compound forms an alcohol, C,,H,,OH, thujamenthol (dihydro-
isothujol), which can be very readily distinguished from tetrahy-
drocarveol (Wallach’).

Thujamenthone is obtained by oxidizing thujamenthol in glacial
acetic acid solution with chromic anhydride. It is a ketone, and
is purified by means of its semicarbazone. It boils at 208° to
209°, has a specific gravity of 0.891 and index of refraction,
np = 1.44708, at 20°. It is optically inactive, and is stable
towards a cold solution of potassium permanganate (Wallach).

Thujamenthonoxime, C,,H,,NOH, crystallizes from dilute methyl
alcohol in transparent prisms, and melts at 95° to 96°.

Isothujamenthonoxime, C,,H,,NO, is obtained by treating thuja-
menthonoxime with phosphorus pentachloride ; it crystallizes from
hot water in long, thin needles, melting at 113° to 114°, and is
more readily soluble than the oxime, melting at 95° to 96°. Unlike
isomenthonoxime, isothujamenthonoxime is very unstable, and is
even reconverted into thujamenthonoxime, melting at 95° to 96°, -
by standing for some time with water.

Thujamenthone semicarbazone, C,,H,, = N-NH-CO-NH,, melts
at 179°. It is slowly reconverted into thujamenthone by boiling
with dilute sulphuric acid.

1Wallach, Ber., 28, 1955; Ann. Chem., 286, 104.

MENTHONE. 295

Oxidation of thujamenthone.'— When thujamenthone is carefully
oxidized with potassium permanganate, it yields the ketonic acid,
C,,H,,0,, which boils at 273°, being converted into the keto-lac-
tone, C,,H,,O,. The semicarbazone of the ketonic acid melts at
174.5°. A solution of sodium hypobromite changes the ketonic
acid into a dibasic acid, C,H,,O,, melting at 134.5°.

The keto-lactone, C,,H,,O,, is produced on oxidizing thujamen-
thone with chromic acid ; it melts at 41°, and yields an owime,
melting at 156° (Wallach).

According to Semmler, the above-mentioned ketonic acid boils
at 273°, being converted into the preceding keto-lactone, C,,H,,O,,
melting at 43°; the oxime melts at 155°. On oxidation, the

keto-lactone gives rise to f-isopropyl laevulinic acid.

5, THUJAMENTHOL, ©,,H,,OH.

Thujamenthol or dihydroisothujol is obtained by reducing
isothujone with sodium and alcohol.’ It is a viscous liquid, hav-
ing an odor resembling that of terpineol. It boils at 211° to
213°, has asp. gr. of 0.895 and a refractive index, np = 1.46345,
at 22°. It yields thujamenthone by oxidation with chromic acid
( Wallach’).

6. MENTHONE, C,,H,,0.

Menthone has the constitutional formula :—

H,C 0H,

It occurs, together with menthol, esters of menthol, menthene
and limonene, in peppermint oil. According to Power and
Kleber,’ the amount of menthone in American oil of peppermint
reaches 12.3 per cent. Andres and Andrejew* found it in Rus-
sian peppermint oil.

The separation of pure menthone from peppermint oil by frac-
tional distillation is impossible, since menthone boils but a few

1Wallach, Ber., 30, 423; Semmler, Ber., 33, 275.

2Wallach, Ber., 28, 1955.

3Schimmel & Co., Semi-Annual Report, April, 1895, 56.

+Andres and Andrejew, Ber., 24, 560, Ref.; Ber., 25, 609.

296 THE TERPENES.

degrees lower than menthol, and cannot, therefore, be separated
from the latter compound. It is prepared, however, by oxidation
of menthol. In this manner optically inactive menthone was first
prepared by Moriya, who heated menthol with potassium chro-
mate and sulphuric acid in a sealed tube at 120° for ten hours.
Later, Atkinson and Yoshida? succeeded in the preparation of
strongly dextrorotatory menthone by repeated treatments of men-
thol with a chromic acid mixture at 135°; they assumed, therefore,
that the product obtained by Moriya contained levo-menthone as
an impurity, and that for this reason alone it appeared optically
inactive.

The comprehensive experiments of Beckmann* have led to a
very simple method for the preparation of menthone, and have
further shown that its optical behavior is quite unusual. Men-
thone is very readily inverted by acids, as will be shown later
more in detail.

Levo-menthone results by the oxidation of levo-menthol if the
action of an excess of acid be avoided as much as possible. Beck-
mann has suggested the following method. To a solution of sixty
grams (one molecule) of potassium dichromate and fifty grams
(two and one-half molecules) of concentrated sulphuric acid in
300 grams of water, which is warmed to about 30°, forty-five
grams of crystallized menthol are added in one portion; the sur-
face of the mixture immediately assumes a deep black color, due to
the formation of a chromium compound. If the mixture be now
vigorously shaken, the liquid takes on a dark color, and becomes
warm ; the menthol at first softens, and is then completely converted
into a black, crystalline chromium compound. The oily men-
thone is not formed until the temperature rises above 53°, which
is generally accomplished, without heating, in about thirty min-
utes ; at this point the chromium compound is suddenly decom-
posed into a brown mass with separation of liquid menthone. If
large quantities of menthol are employed, care must be taken to
cool the mixture so that the temperature does not rise above 55°.

The menthone forms a dark, oily layer on the cold reaction-
product ; it is taken up in ether, and agitated successively with
water and dilute sodium hydroxide in order to remoye the chro-
mium compounds. For further purification, portions of ten to
twenty grams of menthone are rapidly distilled with steam, the
oil is separated, dried over anhydrous sodium sulphate, and rectified.

1Moriya, Journ. Chem. Soc., 1881, 77; Jahresb. Chem., 1881, 629.

2Atkinson and Yoshida, Journ. Chem. Soc., 1882, 50; Jahresb. Chem.,
1882, 775.

3Beckmann, Ann. Chem., 250, 322; 289, 362.

ee a lee Wied Kone wl be eee es

Onis

-_, in

DEXTROROTATORY MENTHONE. 297

Levorotatory menthone, prepared in this way, is a mobile liquid ;
it does not solidify when placed in a freezing mixture, has a soft,
peppermint-like odor, and differs from menthol in its bitter and
sharp taste. It boils at 207°, and has the specific gravity 0.896
at 20°. Menthone, regenerated from its semicarbazone, boils at
208°, has a sp. gr. 0.894 and refractive index, n, = 1.4496
(Wallach ').

The following specific rotatory powers were obtained for five
quantities of menthone prepared at different times, and in each
case the menthone contained no menthol :

[a] p= — 24.78°, — 25.51°, — 26.98°, — 27.12°, — 28.18°.

The menthone was prepared by oxidizing menthol according to
the above-described method ; the menthol melted at 43°, and had
a specific rotatory power, [a] p= — 50.59°, in a ten per cent.
alcoholic solution, and — 49.35° in a twenty per cent. solution.

Dextrorotatory menthone is produced by the action of acids on
levo-menthone. A mixture of ten parts of concentrated sul-
phuric acid and one part of water is allowed to stand for some
time in a freezing mixture ; two parts of levo-menthone are then
added and the mixture is gently shaken until the menthone dis-
solves in the slowly melting acid, forming a yellow liquid. When
solution is complete, the temperature is gradually raised to 30°
and the reaction-product poured onto ice. The resulting dextro-
menthone is immediately extracted with ether and the ethereal
solution washed with soda; the menthone is distilled rapidly with
steam and dried with fused sodium sulphate (Beckmann).

If pure levo-menthone, free from menthol, be employed, the
resultant dextro-menthone does not differ from the levo-modifica-
_ tion in odor, boiling point, ete. Various preparations showed
the specific rotatory powers: [«4]) = + 26.33°, + 26.67°, etc.,
to + 28.14°.

An inactive product is produced by mixing equal quantities of
dextro- and levo-menthone, having rotatory powers of the same
degree but of opposite direction ; this product, however, must be
regarded as a mixture, since, if it be converted into the oxime,
pure levo menthonoxime may be isolated.

When levorotatory menthone is treated with dilute sulphuric
acid, its levorotatory power diminishes until it. reaches zero, and
then becomes dextrorotatory to about + 8°; this change in the
rotatory power is dependent on the temperature, time of action
and concentration of the acid. If dextrorotatory menthone be
treated in the same manner, its dextrorotatory power also di-

1Wallach, Ber., 28, 1955.

298 THE TERPENES.

minishes, and finally reaches a value of about + 8°, which seems
to correspond to a condition of equilibrium. The two modifica-
tions of menthone suffer similar transformations by the action of
dry hydrogen chloride, acetic acid, hot sodium hydroxide solu-
tion, cold sodium alcoholate or boiling water. The rotatory
powers of the menthones slowly change on standing at the ordi-
nary temperature. Respecting the large number of similar obser-
vations of Beckmann, reference must be made to his original pub-
lications.

Menthone does not combine with acid sodium sulphite. It is
converted into menthol by reduction in a moist ethereal solution
with sodium.’ When levo-menthone is heated with ammonium
formate at 190° to 200°, according to Leuckart’s method, the
product consists chiefly of dextrorotatory menthylamine, C,,H,,-
NH, together with some of the levorotatory isomeride.? Levo-
menthylamine is also formed by reducing levo-menthonoxime.

When menthone is added in small portions to a cold mixture
of phosphorus pentachloride and ligroine, hydrochloric acid is
given off, and a monochloride, C,,H,,Cl, and a dichloride, C,,H,,Cl,,
are obtained. The monochloride boils at 205° to 208°, has the
specific gravity at 0° of 0.9833, and is dextrorotatory ; it does
not lose hydrogen chloride even when boiled with quinoline.
The dichloride boils at 150° to 155° under 60 mm. pressure, and
has the specific gravity of 1.0824 at 0° (Berkenheim *).

According to Jiinger and Klages,* chlorotetrahydrocymene,
C,,H,,Cl, is obtained by the action of phosphoric chloride on
menthone ; by successive treatment with bromine and quinoline
it is converted into chlorodihydrocymene, C,,H,,Cl, which boils at
210° to 212° under atmospheric pressure. When chlorodihydro-
cymene is further treated with bromine, and the product is dis-
tilled with quinoline, 3-chlorocymene is produced :

-

i

‘: Pe:

C,H,
3-Chlorocymene.

1 Beckmann, German patent, No. 42,458; Ber., 21, 321, Ref.; Ber., 22, 912.

2Wallach, Ber., 24, 3992; 25, 3313; Wallach and Kuthe, Ann. Chem., 276,
296.

3Berkenheim, Ber., 25, 693.

4Jiinger and Klages, Ber., 29, 314.

ee et ee

$-METHYL ADIPIC ACID. 299

Dibromomenthone,' C,,H,,Br,O, is produced by adding two molec-
ular proportions of bromine to /- or d-menthone dissolved in chlo-
roform. It separates from alcohol in colorless crystals, melts at
79° to 80°, and is dextrorotatory. It is reconverted into men-
thone by the action of glacial acetic acid and zinc dust. With
hydroxylamine, it yields the oxime, C,,H,,Br(OH) = NOH, which
melts at 136° to 137°. When the dibromo-compound is heated
with boiling quinoline, thymol is formed.

By the action of an excess of bromine on menthone, a crystal-
line tetrabromo-m-cresol is obtained, together with a compound,”
C,,H,OBr,; the latter melts and decomposes at 148° to 149°.

8-Methyl adipic acid, C,H,,O,, is formed by the oxidation of
menthone with potassium permanganate (Manasse and Rupe*);
it is also obtained, together with the so-called orymenthylic acid,
C,,H,,O,, by oxidation of menthol with potassium permanganate
or chromic acid, and, according to Semmler, it is one of the prod-
ucts formed in the oxidation of pulegone. The acid is optically
active.

Manasse and Rupe explain the formation of #-methy] adipic acid
from menthone by means of the following formulas :

i, i
H ‘H
H, CH, a
H, bo H.C OOH
es
H 0
H A
H,C CH; H,C CH,
Menthone. Oxymenthylic
acid, the interme-
sé diate ketonic acid.
CH,
{1H
H, :
H, OOH
COOH
8-Methyl adipic
acid.

!1Beckmann and Hichelberg, Ber., 29, 418.
2Baeyer and Seuffert, Ber., 34, 40.
3Manasse and Rupe, Ber., 27, 1820.

300 THE TERPENES.

Oxymenthylic acid is also formed by oxidizing menthone with
chromic acid.’

When menthone is oxidized with Caro’s reagent (potassium
persulphate and concentrated sulphuric acid), it forms the corre-
sponding ¢-lactone,? C,,H,,O, ; it crystallizes from methyl alcohol,
and melts at 46° to 48°. It yields an oxy-acid (m. p. 65° to
66°), and a ketonic acid, whose oxime melts at 100° to 102°.

Levo-menthonoxime, C,,H,,NOH, is prepared by the following
method (Beckmann *). Twenty parts (one molecule) of menthone
are dissolved in two and one-half times its amount of ninety per
cent. alcohol, and treated with twelve parts (1.3 molecules) of hy-
droxylamine hydrochloride and a little more than the theoretical
quantity of acid sodium carbonate. The reaction takes place in
the cold in less than one day, but if the mixture be warmed it is
complete in a few minutes. On the addition of water, the oxime
separates as an oil which soon solidifies ; it is pressed on a plate,
recrystallized from dilute alcohol, and melts at 59°. According
to Wallach,* it boils at 250° to 251°.

If the levo-menthone used in the preparation of the oxime
contains menthol, or is partially inverted, liquid products are
formed which prevent the immediate separation of the solid oxime ;
when these oily compounds are cooled, levo-menthonoxime sepa-
rates in crystals.

Beckmann found the specific rotatory powers of levo-menthon-
oxime obtained at different times, as :

[2] p = — 40.75°, — 41.97°, — 42.51°.

Levo-menthonoxime dissolves in dilute acids and alkalis and
may be recovered from these solutions by means of ether. Men-
thone is formed by allowing the oxime to remain in contact with
dilute sulphuric acid for some time, or by boiling its sulphuric
acid solution ; the rotatory power of this regenerated menthone is,
of course, less than that of the ketone from which the oxime was
prepared, since a portion of the menthone is inverted by the action
of the acid. Concentrated sulphuric acid at 100° converts it into
an isomeric compound, melting at 68° to 83°.

The hydrochloric acid: salt of levo-menthonoxime is precipitated
by passing dry hydrogen chloride into an ethereal solution of the
oxime ; it crystallizes from alcohol in small tablets, which melt at
118° to 119°, and have the specific rotatory power, [a],= —
61.16°. This salt is converted into the levo-oxime by the action
of sodium hydroxide.

1Beckmann and Mehrliinder, Ann. Chem., 289, 367.

?Baeyer and Villiger, Ber., 32, 3625.

3Beckmann, Ann. Chem., 250, 329.
4Wallach, Ann. Chem., 277, 157.

oa

~ ae vi
i i @

ee ee a ee

ISO-LEVO-MENTHONOXIME. 301

Dextro-menthonoxime, C,,H,,NOH, is prepared in the same
manner as the levo-oxime; it is an oil having a slight levoro-
tatory power: [a], = — 4.85° to —6.67°. Thus, the replace-
ment of the oxygen atom in dextrorotatory menthone by the
isonitroso-group (NOH), causes a change in direction of its
optical rotation.

Dextro-menthonoxime hydrochloride is prepared like the levo-
compound; it melts at 95° to 100°, and is deliquescent. Its
specific rotatory power is [@], = — 24.83°.

Levo-menthylamine, C,,H,,NH,, results by the reduction of
levo-menthonoxime with alcohol and sodium.

Several substances derived from levo-menthonoxime have been
prepared by Wallach ;' they are of special interest since they
manifestly stand in a close relation to the olefinic members of the
terpene series.

Iso-levo-menthonoxime,' C,,H,,NOH, is formed when levo-
menthonoxime is dissolved in chloroform, and the molecular pro-
portion of phosphorus pentachloride is added to the solution ; the
product is shaken with water when the reaction is complete. It
is also obtained by heating a solution of levo-menthonoxime in
acetic anhydride with phosphoric anhydride for a short time. It
is, however, more conveniently prepared, when twenty grams
of levo-menthonoxime are added slowly at first and then more
rapidly, with constant agitation, to forty cc. of cold, concentrated
sulphuric acid ; the liquid is then warmed very cautiously until
all of the oxime is dissolved. The color of the solution changes
from yellow to red and brown, and traces of sulphur dioxide are
given off; as soon as the brown color appears, the liquid is poured
into a limited amount of ice-water. Most of the isoxime separates

in small needles, and the residue may be precipitated by neutrali-

zation with sodium hydroxide. (Compare with Beckmann and
Mehrlander.’)

It is very readily soluble in methyl and ethyl alcohols, and
may be recrystallized from hot water; it melts at 119° to 120°,
and boils at 295°. Its specific rotatory power is [a] ) = — 52.25°.
It behaves as a saturated compound, and does not yield menthone
when boiled with acids ; dehydrating agents convert it into men-
thonitrile.

It has been mentioned above that when levyo-menthonoxime is
dissolved in chloroform and treated with phosphorus pentachlo-
ride, and the product is then mixed with water, iso-l-menthonox-

1Wallach, Ann. Chem., 278, 302; 277, 154.

2Mehrliinder, Inaug. Diss. Breslau, 1887; Beckmann and Mebhrliinder,
Ann. Chem., 289, 367.

3802 THE TERPENES.

ime is produced ; however, if the reaction-product be distilled in
vacuum to remove the chloroform and phosphorus oxychloride,
and then heated for some time at 100°, a strong base, C,,H,,.CIN,,
is obtained. This amine crystallizes in well defined prisms, and
melts at 59° to 60°; it is levorotatory, [a], = — 186.35°, and
yields stable salts as C,,H,,CIN,-2HCl.

Phosphoric chloride converts dextro-menthonoxime into an iso-
meric compound, melting at 88°; an oily product results, together
with the solid substance (Beckmann and Mehrlinder’).

Menthonitrile, C,H,,CN, may be prepared directly from levo-
menthonoxime by the action of phosphoric anhydride ; however,
since this reaction takes place very violently, it is better to em-
ploy iso-l-menthonoxime. Thirty grams of the latter are dis-
solved in eighty ec. of chloroform and treated with forty-five
grams of phosphorus pentachloride ; when the evolution of hy-
drochloric acid is complete, the chloroform and phosphorus oxy-
chloride are removed by distillation in vacuum. If the residue
be heated with the free flame under diminished pressure, hydro-
gen chloride is split off, and menthonitrile distills over. The re-
action takes place in two phases: first, the chlorinated base (m. p.
59° to 60°) is formed from the chloride of iso-l-menthonoxime, and
then, at a higher temperature, it is decomposed into menthonitrile
and hydrochorie acid :—

I. 2C,,H,,NCl— HCl + C,,H,,CIN, ;

II. C,,H,,CLN, = HCl + 2C,H,.CN.
It can, therefore, be prepared from the pure base, C,,H,.CIN..
The crude nitrile is washed with sodium hydroxide and purified
by distillation with steam. It is an oil, which rotates the plane
of polarized light to the left, and boils at 225° to 226°; it has a
specific gravity 0.8355 and index of refraction, np = 1.44406,
at 20°.

Menthonitrile differs from iso-l-menthonoxime in behaving as
an unsaturated compound ; it immediately decolorizes bromine
and permanganate. The formation of this nitrile is, therefore,
accompanied by a break in the hexamethylene ring; hence,
menthonitrile and its derivatives belong to the fatty series.

Menthonenic amide,’ C,H,,CONH,, is produced by boiling
menthonitrile with sodium alcoholate for half an hour; it

crystallizes from hot water in brilliant leaflets, melts at 105° to -

106°, and decolorizes bromine.
Menthonenic (decenoic) acid,’ C,H,,COOH, results by the pro-
longed action of alcoholic potash on the nitrile or acid amide ; it

1Beckmann and Mehrliinder, Ann. Chem., 289, 367.
2Wallach, Ann. Chem., 296, 120.

deal

= ghee

a O09 Or Go ie iy ee ee eee i

08 eed

MENTHONE SEMIOXAMAZONE, 303

is conveniently prepared on hydrolyzing the nitrile with sodium
ethylate in sealed tubes at 120°. It boils at 257° to 261°, has
the sp. gr. 0.918 and ny = 1.45109 at 20°; it forms a sparingly
soluble silver salt. Oxidation with permanganate yields 6-methyl
adipic acid.

Aminodecoic acid,' C,,H,,O,N, is prepared from menthone
isoxime ; it separates from water in well formed crystals, melting
at 194° to 195°. Nitrous acid converts it into decenoic acid,
C,,H,,0,, which boils at 257° to 259° and is identical with
menthonenic acid.

When menthonitrile is reduced in an alcoholic solution with
sodium, it yields menthonylamine, C,,H,,NH,, and owyhydro-
menthonylamine, C,,H,(OH)NH,; the former is an aliphatic
isomeride of menthylamine. If menthonylamine be treated with
nitrous acid, an alcohol, menthocitronellol, C,,H,,OH, is formed ;
when this alcohol is oxidized with chromic acid, an aldehyde,
menthocitronellal, C,,H,,O, is obtained. Dimethyl octylene glycol,
C,,H.,,(OH),, is formed by the action of nitrous acid upon oxyhy-
dromenthonylamine. These substances possess the properties of
aliphatic compounds, and bear a close relation to the naturally
occurring aliphatic members of the terpene series. They will be
described with the aliphatic alcohols and aldehydes.

A decoic acid, C,,H,,O,, an open-chain acid, is formed by heating
menthonoxime with an aqueous solution of caustic potash for one
hour, at 220° to 230°; it boils at 249° to 251°, has the sp. gr.
0.905, and the refractive index, np = 1.4373. Its amide crystal-
lizes from water and melts at 108° to 109° (Wallach).

Menthone semicarbazones, C,,H,, = N-NH:CO-NH,.—The de-
rivative obtained from dextro-menthone melts at 172°, and has

the specific rotatory power, [a], = — 3° (ten per cent. glacial

acetic acid solution at 20°); the semicarbazone derived from levo-
menthone crystallizes from alcohol in small needles, melts at 178°,
and has [a], = —3.67°, under same condition as above. A
mixture of the two modifications melts at 175° (Beckmann’).
According to Wallach,’ menthone yields a semicarbazone, melting
at 184°. Rimini*® has also obtained a semicarbazone from perni-
trosomenthone, which melts at 192° to 193°.

Menthone semioxamazone,‘ C,,H,, = N-C,O,N,H,, crystallizes
from alcohol in wh te needles, and melts at 177°.

1Wallach, Ann. Chem., 312, 171.

25eckmann, Ann. Chem., 289, 362.

3Wallach, Ber., 28, 1955; compare Rimini, Gazz. Chim., 30 [I.], 600;
Beckmann, Ann. Chem., 289, 366.

4Kerp and Unger, Ber., 30, 585.

304 THE TERPENES.

Pernitrosomenthone,' C,,H,,N,O,, is formed by the action of so-
dium nitrite on an acetic acid solution of menthonoxime; it is an
oil, which decomposes at 140° when distilled under diminished
pressure. Sulphuric acid and alkalis convert it into menthone.
When treated in an alcoholic solution with semicarbazide hydro-
chloride and sodium acetate, it is converted into a menthone semi-
carbazone, melting at 192° to 193°.

Bisnitrosomenthone, [C,,H,,O(NO) ],, results, together with men-
thoximic acid, when amyl] nitrite is added very slowly and with
constant agitation to a well cooled mixture of one hundred grams
of menthone and twenty-five grams of concentrated hydrochloric
acid ; after two hours standing the mixture is again treated with
twenty-five grams of hydrochloric acid, and, in the course of an-
other two hours, amy! nitrite is continuously added until the total
amount of nitrite employed equals seventy-six grams. The thick
reaction-product, containing some crystals, is shaken with ice and
treated with a dilute solution of sodium hydroxide, which dis-
solves the menthoximic acid. The nitrosomenthone remains un-
dissolved, and is obtained in a yield of about eight per cent. It
is filtered and crystallized from ether; it separates in lustrous
needles, and melts at 112.5° (Baeyer and Manasse’).

It may also be prepared in a yield of forty per cent. if acetyl
chloride be used in place of hydrochloric acid (Baeyer ’).

Bisnitrosomenthone reacts with alcoholic hydrochloric acid
forming menthobisnitrosylic acid, which is a crystalline solid, and
monochloromenthone, which is an oil. When monochloromenthone
is distilled with sodium acetate and glacial acetic acid, it gives a
ketone, C,,H,,O, which is apparently identical with menthenone,
obtained by Kremers from nitrosomenthene (Baeyer *).

Menthoximic acid, C,,H,,O, = NOH, is formed together with bis-
nitrosomenthone, and is identical with the oxime of oxymenthylic
acid, prepared by Beckmann and Mehrlinder* by the action
of hydroxylamine on oxymenthylic acid; the latter acid is a
product of the oxidation of menthol. By treatment with dilute
acids, menthoximic acid is readily converted into oxymenthylic
acid.

According to Baeyer and Manasse, menthoximie acid is pro-
duced in a yield of sixty per cent. by the action of amyl nitrite
and hydrochloric acid on menthone; they assume that tertiary
nitrosomenthone is first formed, which then combines with the

1Rimini, Gazz. Chim., 26 [II.], 502; 30 [I.], 600.
2Baeyer and Manasse, Ber., 27, 1912.

SBaeyer, Ber., 28, 1586.

4Beckmann and Mehrlinder, Ann. Chem., 289, 367.

ee

al rel a

DA ied

NITROMENTHONE. 3805

elements of water and is converted into menthoximic acid (di-
methyl-(2, 6)-oximido-3-octanic acid) :

A, CH,
H A
H, A, H, H,
H, CO +H,0 Hi, ae
‘NO | oie NOH
A H
H,¢C OH, HO CH,
Nitrosomenthone. Menthoximic acid.
Hy;
H ae
H, it
H, COOH
O
H
HC CH,
Oxymenthylic acid.

According to Oehler,' menthoximic acid melts at 103° ; according
to Baeyer and Manasse, it melts at 98.5°.
Oxymethylene menthone,

C=CH(OH)
CHC |

is prepared by the action of sodium and amyl formate on an
ethereal solution of menthone ; it is a colorless oil, boils at 121°
under a pressure of 12 mm. to 13 mm., and has a specific gravity
of 1.002 at 15°. It dissolves in alkalis, and decomposes into
menthone and the alkali salts of formic acid on boiling its alkaline
solutions. It forms a liquid acetyl derivative, bofling at 160°
to 162° under 12 mm. to 13 mm. pressure, and a solid benzoyl
compound, melting at 75° to 76° (Claisen *).

Nitromenthone, C,,H,,O(NO,), is formed by heating menthone
with nitric acid (sp. gr. 1.075) in a sealed tube. It is a light
yellow liquid, boils with slight decomposition at 135° to 140°
(15 mm.), and has the sp. gr. 1.059 at 20°/0°. When reduced
with tin and hydrochloric acid, it yields amidomenthone, C,,H,,-
O-NH,, which boils at 235° to 237°; it forms amidomenthonoxime

1Baeyer and Oehler, Ber., 29, 27.

2Claisen, Ann. Chem., 281, 394.

20

306 THE TERPENES.

hydrochloride (m. p. 110°) by the action of an excess of hy-
droxylamine hydrochloride. Amidomenthonoxime is converted
by reduction into a diamine (b. p. 240° to 243°), whose hydro-
chloride reacts with potassium nitrite, forming an unsaturated
ketone (?), which is possibly isomeric or identical with pulegone.

When amidomenthone is reduced, it yields amidomenthol, boil-
ing at 254°. ’

An acid, C,,H,,NO,, is formed by the action of sodium ethylate
on nitromenthone; it boils at 190° to 195° under 13 mm. pres-
sure (Konowaloff’).

Benzylidene menthone,*® C,,H,,O = CH:C,H,, is readily obtained
in the form of its hydrochloride by saturating a mixture of molec-
ular proportions of menthone and benzaldehyde with dry hydro-
chloric acid gas; after standing for about twelve hours in a cold
place, the solid hydrochloride is washed with a soda solution to
remove excess of hydrogen chloride, is dried, and crystallized
from hot alcohol or petroleum ether. On treating the hydro-
chloride with a solution of sodium ethylate for twenty minutes on
the water-bath, benzylidene menthone is obtained; it is a yellow
oil, and boils at 188° to 189° under 12 mm. pressure. Its hy-
drochloride (C,,H,,O = C,H,)-HCl, crystallizes from alcohol in
white needles, and melts at 140°. The hydrobromide is produced
by passing hydrogen bromide into a glacial acetic acid solution of
benzylidene menthone ; it crystallizes well, and melts with decom-
position at 115° to 116°.

According to Martine,” benzylidene menthone is formed by the
action of benzaldehyde on sodium menthylate; it boils at 195° to
196° (15 mm.), has the rotatory power, [a] p= + 22.8° to+
24.3°, and forms the hydrobromide, melting at 115°.

Benzylidene menthonoxime, C,,H,,(NOH) = CH:'C,H,, crystal-
lizes from alcohol or ether in needles and melts at 161°. On
reduction with alcohol and sodium, it gives rise to a base, benzyli-
dene menthylamine, C,,H,,NH,, which boils at 200° to 205° under
10 mm. pressure.

Benzyl menthol,’ C,,H,,(OH)-CH,-C,H,, is produced by the re-
duction of benzylidene menthone or its hydrochloride with sodium
and alcohol; it separates as a thick oil, boiling at 181° to 183°
(10 mm.). After standing during several months, a small portion
of this oil solidifies, and, after recrystallization from ether, forms
colorless crystals, melting at 111° to 112°. Both oil and crystals

1Konowaloff, Compt. rend., 121, 652; Ber., 31, 1478.

2Martine, Compt. rend., 133, 41.

3 Wallach, Ann. Chem., 305, 261; Ber., 29, 1595; compare Martine, Compt.
rend., 133, 41. ;

MENTHONE DICARBOXYLIC ACID. 307

have the same composition, C,,H,OH, and are probably two
physical-isomeric modifications of the same compound. When
treated with phosphorus pentoxide, benzyl menthol yields a hy-
drocarbon, methyl isopropyl hexahydrofluorene, C,,H,,, boiling at
153° to 155° (10 mm.).

Benzyl menthone, C,,H,,O, results on the oxidation of benzyl
menthol in glacial acetic acid solution with chromic acid ; it is a
viscous oil, boils at 177° to 179° (10 mm.), and yields an oily
oxime ; on reduction, this oxime gives rise to benzyl menthylamine.

Menthone pinacone,' C,,H,.O,, is formed on reducing menthone
in ethereal solution with sodium ; it melts at 94°.

When menthone in an absolute ethereal solution is treated with
sodium wire, and is then saturated with carbon dioxide, a mixture
of products is obtained, which contains, besides unchanged men-
thone and menthol, menthone pinacone, menthone carboxylic and
dicarboxylic acids.”

Menthone carboxylic acid, C,,H,,O-COOH, is a heavy, color-
less oil, is sparingly soluble in water, and its solution gives a
violet coloration with ferric chloride; when heated with dilute
sulphuric acid, it is reconverted into menthone. Its silver salt is
a white solid.

On treating the acid with nitrous acid at ordinary temperature,
isonitrosomenthone, C,,H,,O(NOH), and an ortho-diketone, C,,H,,O,,
are formed ; the former is an oil, is soluble in alkalis, and yields
menthone amine, C,,H,,O-NH,, on reduction with zine dust and
acetic acid ; the ortho-diketone is a reddish oil, insoluble in alkalis.

Menthone dicarboxylic acid, C,,H,,O(COOH),, melts and decom-
poses at 140° to 141°.

It should be mentioned that Flatau and Labbé* separated a

24)

ketone, boiling at 204° to 206°, from Bourbon geranium oil ;

they called this ketone “ a-menthone.” It yields a semicarbazone,
melting at 180°. It will probably be safe to regard “ a-men-
thone” as identical with ordinary levo-menthone, until a more
complete investigation shall prove to the contrary.

A ketone, C,,H,,O, was obtained by Kondakoff* from the ethereal
oil of buchu leaves; this ketone is called ketomenthone. It is a
colorless liquid with a peppermint-like odor; it boils at 208.5° to
209.5° under 760 mm. pressure, has the sp. gr. 0.9004 at 19°/19°,

1Beckmann, Journ. pr. Chem., 55 [II.], 14.

2Q0ddo, Gazz. Chim., 27 [II.], 97.

3Flatau and Labbé, Bull. Soe. Chim., 79 [III.], 788; compare Schimmel &
Co., Semi-Annual Report, Oct., 1898, 52.

4Kondakoff, Journ. pr. Chem., 54 [1I.], 433; Kondakoff and Bachtschéeff,
Journ. pr. Chem., 63 [II.], 49.

308 THE TERPENES.

the optical rotation, [a], = — 16°6’, the index of refraction,
ny = 1.45359, and molecular refraction, 46.28. Its oxime is
liquid and optically active.

When ketomenthone is reduced in methyl alcoholic solution
with sodium, it yields a solid and a liquid menthol, C,,H,OH.
The solid menthol crystallizes in needles, melts at 38.5° to 39°,
has the sp. gr. 0.9006 at 32°/32°, and the index of refraction,
Ny = 1.45869, at 32°; its benzoate melts at 82°. When this
menthol is treated with phosphoric oxide, it is converted into a
menthene, C,,H,,, which boils at 166.5° to 168.5° (785 mm.), has
the sp. gr. 0.8112 at 19°, np, = 1.45109, and [a], = — 13°46’.

The isomeric, liquid menthol boils at 106.5° to 109° (18 mm.),
has the sp. gr. 0.9041 at 21.6°, n, = 1.461793, and [a],=
+ 26°30’; it yields a levorotatory menthene.

Neither of these isomeric menthols appears to be identical with
the natural menthol.

Sym-menthone' (1,3-methylisopropyl cyclohexanone-5), C,,H,,O, is
formed by oxidizing sym-menthol with chromic acid ; it is a colorless
oil of peppermint-like odor, and readily forms a crystalline deriva-
tive with acid sodium sulphite. It boils at 222° (749 mm.), has
the sp. gr. 0.9040 at 18°/4°, the refractive index, np = 1.45359, at
18°, and the molecular refraction, R = 45.98. Its semicarbazone
crystallizes from benzene and melts at 176° to 177°.

7. MENTHOL, C,,H,,OH.

Menthol,” formerly designated as “mentha camphor,” or “ pep-
permint camphor,” occurs, together with menthone, menthene and
terpenes, in peppermint oil. It is deposited in crystals when the
essential oil is cooled ; for its preparation, however, it is better to
first distill off the terpenes and menthene, and then cool the
remaining oil.

When menthone, C,,H,,O, is reduced in the presence of an
excess of nascent hydrogen, as with sodium and alcohol or water,
menthol is the only product ; but with sodium and solvents which
do not themselves liberate hydrogen, as absolute ether, some men-
thone pinacone, C,,H.,.O,, is formed, together with menthol.’ Levo-
and dextro-menthone yield by both methods a strongly levoro-
tatory mixture of menthols. From this mixture the natural -

1Knoevenaugel and Wiedermann, Ann. Chem., 297, 169.

2Oppenheim, Ann. Chem., 120, 350; 130, 176; Journ. pr. Chem., 91, 502;
Gorup-Besanez, Ann. Chem., 119, 245; Beckett and Wright, Journ. Chem.
Soc., 1 [2], 1; Ber., 1875, 1466; Charabot, Compt. rend., 139, 518. :

3Beckmann, Journ. pr. Chem., 55 [II.], 14.

a

MENTHOL. 309

levo-menthol (m. p. 43°), and a dextrorotatory isomenthol (m. p.
78° to 81°, [a], = + 2°) may be separated.

- Menthol and oobi may be separated by converting the
latter into its oxime, extracting with ether, evaporating the extract,
and again extracting with dilute sulphuric acid. This removes the
menthone in the form of its oxime, and leaves the menthol ; it does
not give rise to a transformation into optical isomerides (Beckmann).

Menthol is readily prepared when an ethereal solution of men-
thone is treated successively with sodium and water, these opera-
tions being repeated several times. By this method it is possible
to convert the menthone, occurring together with menthol in pep-
permint oil, into menthol, thus considerably increasing the yield
of the latter compound (Beckmann’ ).

Menthol is also formed in the reduction of pulegone,? C,,H,,O.

It crystallizes in colorless, brilliant prisms, which have a strong
smell of peppermint, and a burning taste; it melts at 43°, boils
at 212°, and possesses a specific gravity of 0.890 at 15°. Its
molecular refractive power * is 47.52, and its heat of combustion *
equals 1509.1 calorimetric units (for one molecule expressed in
grams). Menthol obtained from peppermint oil is optically levo-
rotatory, [4] p= — 59° 6’.

Chromic acid converts menthol into menthone. Phosphoric
anhydride, zine chloride, potassium bisulphate, ete., dehydrate it,
forming menthene, C, HH, ; ; this hydrocarbon is nore readily pre-
pared by distilling menthy] chloride with quinoline. According
to Beckmann,’ menthene also results by the action of concentrated
sulphuric acid on menthol, whilst Wagner ° finds that this reaction
gives rise to a polymeric product, C,,H,,, together with cymene
sulphonic acid and hexahydrocymene (menthane), C,,H,,. The

- transformation of menthol into cymene may be effected by heating

with anhydrous copper sulphate at Ae to 280° (Briihl’). Hexa-
hydrocymene (‘“ menthonaphthene”’), C,,H.,,, is produced by heating
menthol with hydriodic acid and red phosphorus at 200° ; it boils
at 169° to 170.5° (Berkenheim *).

Potassium permanganate oxidizes menthol, forming oxymen-
thylic (ketomenthylic) acid, C,,H,,O,, carbonic, formic, propionic

1 Beckmann, German Patent, No. 42,458; Ber., 22, 912.

2Beckmann and Pleissner, Ann. Chem., 262, 1.

3Briihl, Ber., 27, 457.

4Luginin, Ann. Chim. Phys. [5], 23, 387.

5Beckmann, Ann. Chem., 250, 358.

6G. Wagner, Ber., 27, 1637; St. Tolloczko, Chem. Centr., 1895 [I.], 543;
1898 [I.], 105.

TBriihl, Ber., 24, 3374.

8Berkenheim, Ber., 25, 686.

310 THE TERPENES.

and butyric acids, together with the dibasic #-methyl adipic acid
(Arth’s* 8-pimelic acid), C/H,,O,.

Oxymenthylic acid (2, 6-dimethyl octan-3-onoic acid), C,,H,,O,,
is a thick liquid, sparingly soluble in water, and boils at 280° at
ordinary pressure, or at 173° to 175° (15 mm.); with alkalis it
forms crystalline salts which are readily soluble, whilst its silver
salt is sparingly soluble. Its semicarbazone? crystallizes in prisms
and melts at 152°. Its methyl ester boils at 136° to 137° (17
mm.), and the ethyl ester at 145° (15 mm.). When the ethyl
ester is heated with sodium and xylene, it yields a 1, 3-diketone’
_(isobutyryl methyl ketopentamethylene), C,,H,,O, ; it boils at 115° to
116° (25 mm.), forms a dioxime (m. p. 144°), and is reconverted
into oxymenthylic acid on heating with aqueous potash.

Oxymenthylic acid is most conveniently prepared by the oxida-
tion of menthol in an acetic acid solution with chromic anhydride.
It is a ketonic acid and is converted into menthoximic acid* (m.
p- 96.5°), by treating with hydroxylamine.

§-Methyl adipic acid * (Arth’s f-pimelic acid), C,H,,O,, melts at
88.5° to 89°. Mehrlander described it as normal propyl! succinic
acid, but Arth’® proved the error of this statement. According
to Semmler,® this acid is likewise formed, together with acetone,
during the oxidation of pulegone with permanganate.

The constitution of the oxidation products of menthol are,
therefore, expressed by the same formulas as given under men-
thone.

The sodium salt’ of l1-menthol is formed by heating the latter
compound with sodium in an atmosphere of hydrogen. When it
is heated with acid anhydrides for several hours at 160° to 170°,
it yields the corresponding esters of menthol; the stearate, pre-
pared in this manner, melts at 39°.

Methylenic acetal of menthol * (dimentholic formal or dimenthyl-
methylal), CH,(O-C,,H,,),, is produced by the condensation of
menthol and formaldehyde in the presence of mineral acids; it
separates from alcohol in colorless needles, melts at 56.5°, and
boils with slight decomposition at 337°; [a], = — 77.94° at
24°. It is indifferent to boiling acids and alkalis.

1Arth, Ann. Chim. Phys., 7 [6], 440.

2Baeyer and Oehler, Ber., 29, 27.

3Beckmann and Mehrlinder, Ann. Chem., 289, 367.
4Manasse and Rupe, Ber., 27, 1818.

5 Arth, Ber., 21, 645, Ref.

6Semmler, Ber., 25, 3515; 26, 774.

™Beckmann, Journ. pr. Chem., 55 [II.], 14.

8Brochet, Compt. rend', 128, 612; Wedekind, Ber., 34, 813.

* - oe
a a

or.
ore

ae eee

MENTHYL BENZOYL ESTER. 311

Chloromethyl menthyl oxide,’ C,,H,,O-CH,C], is obtained by sat-
urating a mixture of menthol and formalin solution with hydro-
gen chloride at the temperature of the water-bath. It is a color-
less oil, boils at 160° to 163° under 13 mm. to 16 mm. pressure,
has the sp. gr. 0.9821 at 4° and the rotatory power, [¢])=
— 172°.57,at 27°. The action of water converts it into menthol,
formaldehyde and hydrogen chloride; when distilled under re-
duced pressure it suffers partial decomposition and yields methy-
lenic acetal of menthol, C,,H,,0,,.

Menthyl acetoacetate,’ C,,H,.O,, is obtained by heating menthol
and ethyl acetoacetate at 140° to 150° during four hours; it
crystallizes in needles, melts at 30° to 32°, boils at 145° under 11
mm. pressure, and has the specific rotatory power, [a], = — 56.6°.
Its phenylhydrazone melts at 81° to 83°.

Menthyl ethyl ether, C,,H,,OC,H,, is produced by the action of
ethyl iodide on sodium menthylate. It is a liquid, boiling at
211.5° to 212° under 750 mm., and has a slight odor of menthol ;
it has a specific gravity of 0.8513 at 20° or 0.8535 at 17.1°, and
the refractive power, np = 1.44347, at 17.1° (Brihl*).

Menschutkin‘ investigated the speed of the ester formation of
menthol and from his results determined that it is a secondary
alcohol.

Menthyl acetate, C,,H,,O-COCH,, is a thick, strongly refractive
liquid, which boils at 224° and is levorotatory, [a], = — 114°.
(Compare with Power and Kleber°).

Menthyl butyrate, C,,H,,O-COC,H., boils at 230° to 240° and
has the rotatory power, [4] p= — 88°8’.

The following esters were prepared by Arth.*

Menthyl succinoxyl ester, C,,H,,O-CO-CH,CH,-COOH, melts
~ at 62°, and has the specific rotatory power, [a])= — 59.63°.

Menthyl succinyl ester, C,H,(COOC,,H,,),, forms triclinic crys-
tals, and melts at 62°; it decomposes into succinic acid and men-
thene when heated in a sealed tube at 220°. Its specific rotatory
power is [a] = — 81.52°.

Menthyl benzoyl ester,’ C,H,COOC,,H,,, crystallizes in triclinic
crystals, melts at 54°, and has the rotatory power, [4]>=
— 90.92°.

1Wedekind, German Patent, No. 119,008; Ber., 34, 813.

2Cohn, Monatsh., 21, 200.

3Briihl, Ber., 24, 3375 and 3703.

4Menschutkin, Journ. Russ. Chem. Soc., 13, 569.

5Arth, Ann. Chim. Phys. [6], 7, 433 to 499; Ber., 19, 436, Ref.

6Power and Kleber, Pharm. Rund., 12, 162; Archiv. d. Pharm., 232, 653.

7™Compare with Beckmann, Ann. Chem., 262, 31; Journ. pr. Chem., 55
[II], 16.

312 THE TERPENES.

Menthyl phthaloxyl ester, HOOC-C,H,-CO-OC,,H,,, melts at
110°, and has the specific rotatory power, [a] = — 105.55°.
Its magnesium salt is almost insoluble in water.

Menthyl phthalyl ester, C,H,(COOC,,H,,)., separates from ether
in triclinic crystals, and melts at 133°. (al, = — 94.72°.

Menthyl carbonate, CO(OC,,H,,),, is obtained, together with
menthyl carbamate, when cyanogen is allowed to act on sodium
menthylate suspended in toluene; the toluene is removed by
steam distillation when the reaction is complete. The carbamate
crystallizes from the cold residue, and is filtered off ; the carbon-
ate is obtained by evaporation of the filtrate. It is recrystallized
from alcohol or toluene, and melts at 105°.

It is also formed when a well cooled mixture of a solution of
menthol in chloroform and pyridine is treated very slowly with
a solution of carbony! chloride in chloroform ; after standing for
a day in a cold place, the product is distilled with steam, the
solid residue is washed with hot water, and crystallized from alco-
hol (Erdmann ‘).

Menthyl carbamate, C,,H,,O-CO-NH,, is purified by recrystal-
lizing the crystals, obtained as suggested under the preceding
compound, from alcohol. It crystallizes in orthorhombic prisms,
melts at 165°, and has the specific rotatory power, [a],= —
85.11°. It combines with benzaldehyde, forming benzylidene
menthyl carbamate ; this compound melts at 143°.

Menthyl phenylcarbamate, C,,H,,O-CO-NHC,H,, is formed by
the combination of phenylcarbimide with menthol; it separates
from alcohol in silky needles, melting at 111° (Leuckart’).

When this compound, prepared from natural menthol, is
saponified with alcoholic sodium ethylate at 150°, it yields some
inactive menthol,’ melting at 49° to 51°.

Sodium menthylxanthate,‘ C,,H,,O-CS-SNa, results when carbon
bisulphide is allowed to act on sodium menthylate suspended in
ether. The free acid is an oil, which decomposes very readily.
The dark, amorphous cupric salt, which is precipitated from
aqueous solutions of the sodium salt by copper sulphate, is con-
verted into the yellow, crystalline cuprous salt, C,,H,,O-CS:SCu,
by heating.

Methyl menthylxanthate,* C,,H,,O-CS:‘SCH,, is formed when a
solution of menthol in dry toluene is successively treated with
sodium, carbon bisulphide, and methyl iodide; it melts at 39°.

1Erdmann, Journ. pr. Chem., 56 [II.], 1.
2Leuckart, Ber., 20, 115.

3Beckmann, Journ. pr. Chem., 55 [II.], 14.
4Bamberger and Lodter, Ber., 23, 213.

MENTHYL CHLORIDE. 313

When submitted to distillation, it yields methyl mercaptan and a
menthene, C,,H,,, of a high specific rotatory power, [a] ») = 114.77°
to 116.06°.

Menthyl dixanthate,' (C,,H,,O),C,S,, is formed by the conden-
sation of sodium menthylxanthate with iodine ; it forms yellow
erystals. When distilled it gives a menthene, having the rotatory
power, [a], = 111.56°.

A number of the fatty acid esters of menthol have been pre-
pared, and investigated by Tschtigaeff.’

Menthyl chloride, C,,H,,Cl, bromide and iodide, prepared by
the action of the phosphorus pentahalogen derivatives on men-
thol, are identical with menthene hydrochloride, hydrobromide
and hydriodide, which are produced by the addition of the halogen
hydride to menthene. They react like derivatives of tertiary
menthol, but are doubtless to be regarded as mixtures of at least
two isomerides.

Menthyl chloride (menthene hydrochloride *), C,,H,,Cl, is formed,
together with menthene, by treating menthol with phosphorus
pentachloride, by heating menthol with concentrated hydrochloric
acid, or by heating menthene with concentrated hydrochloric acid
at 205° for six hours. It boils at 209.5° to 210.5°, and has the
specific gravity 0.947 at 15°. It yields menthene when treated
with zine dust and acetic acid or with sodium mentholate; on re-
duction with sodium and alcohol, it gives rise to hexahydrocymene
(menthane), C,,H,,.

According to Kursanoff,* when menthyl chloride is dissolved
in ether and the solution is boiled with sodium, it yields a mix-
ture of menthene, menthane, and two dimenthyls, C,,H,,, one of
which is a liquid. The crystalline dimenthyl, C,,H,,, is readily
- soluble in ether and benzene, and crystallizes from cold alcohol or
benzene in well developed crystals, which melt at 105.5° to 106°,
and boil at 185° to 186° (21 mm.); it has the specific rotatory
power, [4],= — 51° 18’, in a 19.4 per cent. benzene solution.
The liquid dimenthyl is probably a stereoisomeride of the crystal-
line derivative.

The formation of the crystalline dimenthyl from crude menthy!
chloride, as well as by the action of sodium on an ethereal solu-
tion of menthyl] iodide, indicates that the crude halogen esters of

iTschtigaeff, Ber., 32, 3332.

2?Tschtigaeff, Ber., 31, 364.

sWaller, Ann. Chem., 32, 292; Oppenheim, Ann. Chem., 130, 177; Berken-
heim, Ber., 29, 686; Kondakoff, Ber., 28, 1619; Jiinger and Klages, Ber., 29,
317; Kursanoff, Journ. Russ. Phys. Chem. Soc., 33, 289.

4Kursanoff, Journ. Russ. Phys. Chem. Soc., 33, 289.

314 THE TERPENES.

menthol contain some secondary compounds, together with deriv-
atives of tertiary menthol (Kursanoff ).

When |-menthyl chloride is treated with zinc ethyl, it gives
rise to ethyl menthane, C,,H,,.C,H,; the latter boils at 209° to
210° at 730 mm. pressure, has the sp. gr. 0.8275 at 0°/0°, and
the specific rotation, [a], = — 12°15’.

Menthyl bromide (menthene hydrobromide'), C,,H,,Br, is pro-
duced by the action of phosphorus pentabromide or hydrobromic
acid on menthol; it also results by treating menthene with a
saturated solution of hydrobromic acid. It boils at 100° to
103° at 13 mm., and has the specific gravity 1.155 to 1.166 at 23°.

Menthyl iodide (menthene hydriodide’), C,,H,,I, is obtained by
the action of hydriodic acid on menthol or ‘menthene ; it boils at
124° to 126° (18 mm.), and has the specific gravity 1.3155 at
16.5°.. Moist silver oxide converts it into tertiary menthol, thus
giving rise to a transformation of secondary into tertiary menthol.

Menthol is a saturated secondary alcohol, and its constitution
is represented by the accompanying formula:

H,C CH,
Menthol.

It has already been mentioned that when d- or l-menthone is
reduced with sodium, the corresponding d- and l-menthols are not
obtained, but rather a strongly levorotatory mixture of menthols
is formed, from which the ordinary I-menthol (m. p. 43,° [@]p
= — 49.3°), and a dextrorotatory isomenthol may be separated.

Isomenthol*® is separated from the mixture by converting the
menthols into their benzoyl esters; menthyl benzoate is a solid

m. p. 54°), while csomenthyl benzoate is a liquid. On saponifi-
cation of the liquid ester, isomenthol is obtained and crystallizes
after standing some time. It melts at 78° to 81° and is slightly
dextrorotatory, [a], =-+ 2.03°. On-oxidation with chromic

1Kondakoff, Ber., 28, 1618.

?Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257; Berkenheim,

Ber., 25, 696.
3Beckmann, Journ. pr. Chem., 55, 14.

%
t
z

hE

/

a ee eee

os A oe

CIS-SYMMETRICAL MENTHOL. 315

acid, isomenthol yields a dezxtro-menthone, which has a stronger
dextrorotatory power than the d-menthone prepared by the inver-
sion of 1-menthone.

Dextro-menthol, corresponding to the natural levo-menthol, has
not yet been obtained.

In an investigation of the ethereal oil of buchu leaves,
Kondakoff' found that the best samples of oil from Barosma
betulina and B. serratifolia contain about ten per cent. of hydro-
carbons, C,,H,, (d-limonene and dipentene), sixty per cent. of
ketomenthone, C,,H,,O (see under menthone), and five per cent.
of diosphenol.

Diosphenol, C,,H,,O, or C,,H,,O,, is an inactive, phenolic alde-
hyde, and melts at 82°. On reduction with hydriodic acid and
phosphorus at 210°, it yields a hydrocarbon, C,,H,,, of the hexa-
hydrocymene series ; it boils at 165° to 168° (762 mm.). When
reduced with sodium and alcohol, diosphenol gives an inactive
menthol, a crystalline glycol, C,,H,,O,, and a stereomeric, liquid
glycol, C,,H,,O,.

The inactive menthol, C,,H,,OH, is volatile with steam, boils at .
215° to 216° (763 mm.), has a sp. gr. 0.9052 at 20°, and the
index of refraction, np = 1.464456. It yields an inactive iodide,
C,,H,,[, which boils at 126.5° (17 mm.). When this iodide is
treated with alcoholic potash, an active menthene, C,,H,,, results,
which boils at 168° to 169°, has the sp. gr. 0.8158 at 19.8°,
ny = 1.45909, and [a], = — 37’.

The crystalline glycol, C,,H,,O.,, is optically active and odorless ;
it crystallizes in colorless needles, melts at 92°, has a sharp, cool-
ing taste, and is not volatile with steam. When heated with hy-
driodic acid it gives a liquid menthyl iodide, C,,H,,I, which boils
at 112° to 114° (9 mm.), has the sp. gr. 1.359 at 20.6°, and
n, = 1.520771.

The liquid glycol, C,,H.,,O,, is stereomeric with the crystalline
glycol ; it boils at 141.5° to 145° (13 mm.), has the sp. gr. 9.995
at 21.6°, and ny = 1.47877.

In conclusion, two alcohols, C,,H,,OH, isomeric with menthol,
but synthetically prepared, should be mentioned.

Cis-symmetrical menthol (cis-1, 3-methyl isopropyl cyclohexanol-
5), C,,H,,OH, is an alcohol, isomeric with natural menthol, which
Knoevenagel ? prepared synthetically by the action of hydriodic
acid, zine dust and glacial acetic acid on trans-hexahydro-1, 3, 5-
earvacrol, C,,H,,OH. It boils at 226° to 227° (760 mm.), has
a specific gravity 0.9020 and refractive index, np = 1.46454, at

1Kondakoff and Bachtschéeff, Journ. pr. Chem., 63 [II.], 49.
2Knoevenagel and Weidermann, Ann. Chem., 297, 169.

20 ~ 29

316 THE TERPENES.

13.6°, and a molecular refraction, Z= 47.67. It has an odor
suggesting that of natural menthol, is not acted upon by bromine
or potassium: permanganate, but is converted into symmetrical
menthone on oxidation with chromic acid. Its acetate boils at
235° to 236° (752 mm.), and the phenylurethane crystallizes from
a mixture of alcohol and petroleum ether, and melts at 88°. The
chloride, bromide and iodide are liquids.

An alcohol,’ C,,H,,OH, isomeric with, and having the same
structure as, natural l-menthol, is formed by the reduction of
3-methyl-6-isopropyl-A’-keto-R-hexene. It boils at 202° to 204°,
has the sp. gr. 0.910 at 20°, and possesses an odor recalling that
of peppermint; it does not yield a phenylurethane. When
treated with phosphoric anhydride, it gives rise to an inactive
menthene, C,,H,,, boiling at 165° to 167°.

18?

8, TERTIARY CARVOMENTHOL, C,,H,,OH.

Tertiary carvomenthy] iodide, C,,H,,I, is formed, when carvo-
menthene is dissolved in acetic acid and treated with hydriodic
acid ; the iodine atom in this compound is attached to that atom
of carbon which carries the methyl group. This follows the
common rule that when a halogen hydride combines with an un-
saturated compound, the halogen atom attaches itself to the least
hydrogenized carbon atom. If this iodide, C,,H,,I, be dissolved
in acetic acid, and decomposed with silver acetate, it is partially
reverted into carvomenthene, while the remaining portion is con-
verted into the acetate of tertiary carvomenthol (Baeyer’”).

Hi, Hg Hy
I OCOCH,
- |

ca - H, ees H, Hy
H.C CH, <= H,Q OH, H.C CH,
LZ
H sf H
C;H, C,H, CH,
Carvomenthene. Tertiary carvomenthyl Tertiary carvomenthyl
iodide. acetate.

_ Tertiary carvomenthol is obtained by the hydrolysis of its
acetate. It* is also produced by treating carvomenthyl chloride
or bromide with moist silver oxide ; a small quantity of the com-
pound, C,,H.,,O, (m. p. 101° to 102°), is formed at the same time.
18. H. Baer, Inaug. Diss., Leipzig, 1898; Schimmel & Co., Semi-Annual
Report, Oct., 1898, 49.
2Baeyer, Ber., 26, 2270.
3Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257.

TERTIARY MENTHYL METHYL ETHER. 317

Tertiary carvomenthol bas a slight odor, and boils at 96° to
100° under a pressure of 17 mm. It reacts as a tertiary alcohol
towards chromic acid. Hydrobromic acid in a glacial acetic acid
solution converts it at once into tertiary carvomenthyl bromide ;!
this is a heavy oil, which yields carvomenthene, boiling at 174.5°,
when distilled with quinoline.

9. TERTIARY MENTHOL, C,,H,,OH.

Tertiary menthy] iodide is produced by treating menthene with
an acetic acid solution of hydrogen iodide ; if this halogen deriva-
tive be decomposed with silver acetate and acetic acid, it gives
menthene and the acetate of tertiary menthol (Baeyer ”).

ay Hy /H;
H H H
Hf H, H, H, H, i
Hy, Yas <= H.C (CH, H, H,
I ‘woooen,
H, (ny, C,H,
Menthene. Tertiary menthyl Tertiary menthyl
iodide. acetate.

Tertiary menthol is obtained by the saponification of its acetate.
It is also formed by the action of moist silver oxide on menthyl
iodide.'

Tertiary menthol is produced by heating menthene with tri-
chloracetic acid at 70° to 90° for half an hour, and agitating the
product with potash for 12 hours.’

It has a faint odor of peppermint, is decomposed on distillation
at ordinary pressure, but boils undecomposed at 97° to 101°
under a pressure of 20 mm. It solidifies to a vitreous mass when
cooled with solid carbonic anhydride. It behaves as a tertiary
alcohol towards chromic acid.

Tertiary menthyl bromide, C,,H,,Br, is readily prepared by treat-
ing a glacial acetic acid solution of tertiary menthol with hydrogen
bromide. It yields menthene, boiling at 167.5°, when heated
with quinoline.

Tertiary menthyl methyl ether, C,,H,,OCH,, is obtained, together
with a monomethy] terpine, by the following method.

'Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257.
2Baeyer, Ber., 26, 2270.
3Masson and Reychler, Ber., 29, 1843.

318 THE TERPENES.

The methy] ether of crystallized terpineol (m. p. 35°) is shaken
with hydriodic acid (sp. gr. 1.7) for fifteen minutes, thus forming
the hydriodide. ‘This is washed with sodium sulphite and bicar-
bonate, extracted with ether, and the ethereal solution dried and
treated directly with glacial acetic acid and zinc dust, care being
taken not to allow the temperature to rise above 25°. When the
reaction is complete, an excess of: sodium hydroxide is added, and
the product distilled with steam. Some terpinyl methyl ether is
regenerated during the reaction, and is eliminated by treating the
crude product with potassium permanganate. The acetate of a
methyl terpine, C,,H,,(OCH,)OCOCH,, is also formed by the re-
placement of the iodine atom in the above-mentioned hydriodide
with the acetyl group. This acetate yields monomethy] terpine
by boiling with sodium hydroxide. The terpine is separated
from menthyl methyl ether by distillation over the alloy of sodium
and potassium, the terpine being quantitatively retained in the
residue, while the pure methyl ether of tertiary menthol is found
in the distillate (Baeyer’).

It has a faint odor of cymene, boils at about 210°, and is not
attacked by permanganate. It combines with hydrobromic acid,
forming tertiary menthyl bromide, which is converted into
menthene on distillation with quinoline; the resultant menthene
boils at 167.5°, and forms a nitrosochloride, melting at 146°.

Baeyer’s conclusions as to the orientation of these compounds
are opposed to the views regarding the constitution of terpineol
(m. p. 35°), which have been expressed by both Wallach and
Tiemann. (Compare also with the publications of Kondakoff.’)

10. TERPINE, C,,H,,(OH),.

Terpine is the alcohol corresponding to dipentene dihydrochlo-
ride. It was believed until quite recently that the constitutions
of these two compounds were represented by the formulas :—

‘H,
C1
a
usa H, Hy
H, H, and H,
CCl
H
H,C CH, H,C H,
Dipentene dihydrochloride. Terpine.

1 Baeyer, Ber., 26, 2560.
2?Kondakoff, Ber., 28, 1618; Journ. pr. Chem., 60 [II.], 257.

s YSc

= 7 " he
7. ho - , , —.
SS ee. Or Oe ee a

a

TRANS-TERPINE. 319

This terpine formula, however, does not readily conform with
the formation of terebic acid by the oxidation of terpine, since
terebic acid possesses the constitution :—

po

H,C CH,

Moreover, the oxidation of terpine’ with chromic anhydride
yields the keto-lactone, C,,H,,O,, which is obtained by the oxida-
tion of terpineol (m. p. 35°). Hence, it is possible that a chlorine
atom in dipentene dihydrochloride and a hydroxyl-group in ter-
pine are not attached to carbon atom 4, but rather to carbon atom
8; = two compounds would then be represented by the for-
mulas :—

H 3 H;

Cl OH
H, i H, CH,
HC H, H, H,

and

‘H

Cl

* NS
H;,;C CH; H,C CH,

Dipentene dihydrochloride. Terpine.

The determination of the exact constitution of terpine is, natu-
rally, of fundamental importance for the orientation in the terpene
series. Perhaps two terpines exist which correspond to the above
formulas, since Baeyer’? has found that the dihydrochloride and
dihydrobromide of dipentene, and terpine itself exist in two forms
designated as the trans- and cis-modification.

Trans-terpine corresponds to the well known dipentene dihydro-
bromide, melting at 64°, and is prepared by dissolving this com-
pound in ten times its amount of glacial acetic acid and gradually
treating the ice-cold solution with an excess of silver acetate. The
product is filtered after standing for some time, and the filtrate is
neutralized with soda and extracted with ether. The ethereal solu-
tion is treated with alcoholic potash to saponify the acetyl com-
pound, and the reaction-product is then distilled with steam ;
hydrocarbons and terpineol are so removed, while trans-terpine is
obtained from the cold residue (Baeyer’).

'Tiemann and Schmidt, Ber., 28, 1781.
?Baeyer, Ber., 26, 2865.

320 THE TERPENES.

Trans-terpine crystallizes without water of crystallization, melts
at 156° to 158° and boils at 263° to 265°. It is readily soluble
in alcohol, more sparingly in water, ether and ethyl acetate, and
separates from the latter solvent in beautiful, short prisms or six-
sided tablets, having a strong, vitreous luster. When it is treated
with hydrogen bromide in a glacial acetic acid solution, it yields
almost exclusively trans-dipentene dihydrobromide, melting at 64°.
Dilute sulphuric acid converts trans- and cis-terpine into terpineol.

Cis-terpine corresponds to cis-dipentene dihydrobromide (m. p.
39°), and may be obtained from this dihydrobromide according to
the method described under trans-terpine (Baeyer' ).

While many terpenes yield trans-dipentene dihydrochloride and
dibydrobromide exclusively or in preponderant quantities, on the
other hand the transformation of the same terpenes into terpine
always gives cis-terpine, which has the peculiarity of crystallizing
with one molecule of water; in such cases, therefore, terpine
hydrate, C,,H,(OH), + H,O, is always produced and may be
converted into cis-terpine by the elimination of the water of
crystallization.

It further merits notice that Tiemann and Schmidt? do not re-
gard terpine hydrate as a terpine containing water of crystalliza-
tion, but rather as an aliphatic alcohol.

Terpine hydrate, C,,H,,(OH), + H,O, results when pinene or
limonene (dipentene) is allowed to stand in contact with dilute
mineral acids for a long time at ordinary temperature. Of the
following methods which have been proposed for its preparation,
the one suggested by Hempel is to be preferred.

According to Wiggers* and Deville,* a mixture of three liters
of eighty-five per cent. alcohol, one liter of ordinary nitric acid,
and four liters of turpentine oil is allowed to stand for one or one
and one-half months.

According to Tilden,’ two and one-half volumes of turpentine
are mixed with one volume of methyl alcohol and one volume of
nitric acid of sp. gr. 1.4; the mixture is allowed to stand for two
days, and is then poured into a flat basin, small quantities of
methyl] alcohol being added every two days.

According to Hempel,° whose method was employed by Wal-
lach,’ a mixture of eight parts of turpentine oil, two parts of alco-

1 Baeyer, Ber., 26, 2865.

2Tiemann and Schmidt, Ber., 28, 1781.

3Wiggers, Ann. Chem., 57, 247.

4Deville, Ann. Chem., 71, 348.

5Tilden, Jahresb. Chem., 1878, 638.

SHempel, Ann. Chem., 180, 73.
TWallach, Ann. Chem., 227, 284.

ha ae

le ee

TERPINE - HYDRATE. 321

hol, and two parts of nitric acid of sp. gr. 1.255 is placed in flat
basins. After standing for a few days the mother-liquor is
poured off from the crystals of terpine hydrate, and is neutralized
with an alkali, after which treatment a second crop of crystals
separates. The preparation of this compound is most successful
during the cool seasons of the year.’

Terpine hydrate is also formed when dipentene dihydrochloride
is treated with aqueous alcohol,’ or when limonene hydrochloride
is mixed with water and allowed to stand for some time.’ It re-
sults if terpineol be shaken with dilute acid for a considerable time.

It crystallizes from alcohol in transparent, well defined, mono-
clinic* prisms, and dissolves in 200 parts of cold, and twenty-two
parts of boiling water ;° 14.49 parts of terpine hydrate dissolve
in 100 parts of eighty-five per cent. alcohol‘; it is insoluble in
ligroine. Contrary to the earlier publications, Wallach® found
that when it is heated in a capillary tube it commences to coagu-
late and soften above 100°, and melts at 116° to 117°, the fusion
being accompanied by frothing and sublimation of some of the
substance due to the removal of water of crystallization. It does
not melt when boiled with a quantity of water insufficient for its
solution. On distillation the water of crystallization is first given
off and carries over some terpine hydrate ; the anhydrous terpine,
C,,H,,(OH),, then boils at 258° (corr.). Terpine is likewise
formed when the hydrate is dried over sulphuric acid.

Anhydrous terpine (cis-terpine) melts at 102° or at 104° to
105°, according to its purity. It is very hygroscopic. It be-
haves as a saturated compound, being readily converted into
dipentene dihydrochloride or dihydrobromide on treatment with
phosphorus trichloride or tribromide ; the halogen hydrides also
‘react with terpine, forming the corresponding dipentene addition-
products. It has already been noted under the derivatives of
dipentene that the above suggested reactions yield a mixture of
the cis- and trans-isomerides (Baeyer).

The behavior of terpine hydrate towards dehydrating agents
has frequently been a subject of investigation. It was formerly
believed that a homogeneous substance resulted by heating terpine
hydrate with dilute acids; Tilden’ recognized, however, that an
' oxidized compound, C,,H,,O, was formed, together with terpenes,
1Wallach, Ann. Chem., 227, 284.
2Flawitzky, Ber., 12, 2358.
3Wallach and Kremers, Ann. Chem., 270, 188.
4Deville, Ann. Chem., 71, 348.
6Blanchet and Sell, Ann. Chem., 6, 268.

6Wallach, Ann. Chem., 230, 247.
1Tilden, Jahresb. Chem., 1878, 639.

21

322 THE TERPENES.

C,,H,,- Detailed researches regarding this reaction have been
made by Wallach.

When terpine hydrate is boiled with dilute sulphuric acid (one
part of acid to two parts of water), terpinene, terpinolene and ter-
pineol are formed ; when a very dilute acid (one volume of sul-
phuric acid to seven volumes of water) is used, it yields a product
consisting largely of terpinene, with almost no terpineol.

If the hydrate be heated with twenty per cent. phosphoric acid, it
is changed chiefly into terpineol, while a small quantity of terpino-
lene and dipentene, but no terpinene, results. Boiling glacial acetic
acid slowly converts terpine hydrate into terpineol ; but when heated
with glacial acetic acid in a sealed tube at 190° to 200°, terpinene is
the principal product. It is converted into dipentene and terpineol
by heating with acid potassium sulphate at 190° to 200°. In all
these reactions small quantities of cineole are produced.

The elimination of water from terpine hydrate, under all con-
ditions, at first yields “‘terpineol” and a little cineole. It was
explained under terpineol that this “terpineol” obtained by Wal-
lach by dehydrating terpine hydrate was later found to be a mix-
ture. (See page 254.)

If ten grams of terpine hydrate are dissolved in twenty
grams of cold, colorless, concentrated nitric acid, and the re-
sultant clear, rose-colored liquid be very gently warmed, an oil
separates which, according to Wallach,’ is to be regarded as the
nitric acid ester of terpine (or terpineol?) ; when this oil is treated
with sodium hydroxide and distilled with steam, it yields some
terpine hydrate and products similar to those obtained by the
action of other acids on terpine hydrate.

A mono-acetyl ester of terpine, C,,H,,O(C,H,O,), was obtained by ©

Oppenheim? by heating terpine hydrate with acetic anhydride.
It has an odor like that of orange, and boils at 140° to 150°
under a pressure of 20 mm.

Hexahydrocymene, C,,H,,, is formed by the action of concen-
trated hydriodic acid on terpine hydrate at 210°. It boils at
168° to 170°, and has the specific gravity of 0.797 at 15° (A.
Schtschukarew’).

The oxidation of terpine hydrate with nitric acid yields terebic,
para-toluic, and terephthalic acids, whilst chromic anhydride
converts it into acetic and terpenylic acids (Hempel *).

1Wallach, Ann. Chem., 230, 253; 239, 17; compare Bouchardat and Voiry,
Compt. rend., 104, 996; 106, 663; Ann. Chim. Phys. [6], 16, 251; Wallach,
Ann. Chem., 246, 265; 252, 133.

2Oppenheim, Ann. Chem., 129, 157.

3Schtschukarew, Ber., 23, 433, Ref.

‘Hempel, Ann. Chem., 180, 71.

OD eee

CINEOLE. 323

An aqueous solution of terpine hydrate is not acted on by
potassium permanganate at the ordinary temperature, but, on
warming, it is resolved into acetic acid, oxalic acid, etc;
terpenylic acid is not formed in this reaction (Tiemann and
Schmidt’).

Cis-terpine in a hot, glacial acetic acid solution is converted by
chromic anhydride into an orange-colored chromium compound,
which, on heating with glacial acetic acid, yields terpine hydrate
and the keto-lactone, C,,H,,O,, described by Tiemann and Schmidt
as methoethylheptanonolide ; the same keto-lactone was obtained
by Wallach in the oxidation of terpineol (m. p. 35°) with potas-
sium permanganate.

11. MENTHENE GLYCOL, C,,H,,(OH),.

Menthene glycol was obtained, together with other substances,
by Wagner by the action of potassium permanganate on menthene ;
it has been described under menthene.

12, CINEOLE, C,,H,,0.

Cineole is a widely distributed constituent of many ethereal
oils. It was first characterized as a chemical individual and called
cineole by Wallach and Brass,’ who separated it in a condition of
purity from oil of levant wormseed, by means of its hydrochloric
acid derivative. A compound having the formula, C,,H,.O, had
already been detected in wormseed oil by earlier investigators, but
had never been isolated in a pure condition.

Simultaneous with the recognition of cineole in wormseed oil,
Wallach* showed that it is identical with the oxidized constituent
of oil of cajeput, which was formerly called “cajeputol.” Cineole
was then found in various ethereal oils, among which may be
mentioned oil of rosemary, in which cineole was discovered by
Weber,‘ in eucalyptus oil by Jahns® and by Wallach and Gilde-
meister,’ in oil of sage, laurel leaf oil and laurel berry oil by
Wallach.’ It also occurs in the oil of cheken-leaves, galangal

1Tiemann and Schmidt, Ber., 28, 1781.

2Wallach and Brass, Ann. Chem., 225, 291.

3Wallach, Ann. Chem., 225, 315.

4Weber, Ann. Chem., 238, 90.

5Jahns, Ber., 17, 2941.

Wallach and Gildemeister, Ann. Chem., 246, 278; compare Arch. Pharm.,
1885, 52.

7Wallach, Ann. Chem., 252, 94.

324 THE TERPENES.

oil, lavender oil, spike oil, cinnamon oils, zedoary oil, myrtle oil,
canella oil, iva oil, basilicum oil, peppermint oil, Russian spear-
mint oil, camphor oil, different eucalyptus and cardamom
oils, ete.

Cineole is formed, together with terpenes and terpineol, when
terpine hydrate is boiled with dilute acids. Crystallized terpineol
(m. p. 35°) and liquid “terpineol,” which is known to be a
mixture of various compounds, may be partially converted into
cineole by boiling with dilute phosphoric acid or oxalic acid
(Wallach'). Similar observations were subsequently made by
Bouchardat and Voiry,? who called it “terpane.” Cineole has
also been termed “ eucalyptol.”’

In order to prepare it, rectified oil of levant wormseed is cooled
by a freezing mixture and saturated with dry hydrochloric acid
gas ; the resultant crystalline cineole hydrochloride is pressed on a
porous plate in the cold, decomposed by water, and the separated
oil distilled in a current of steam. Chemically pure cineole is
obtained by a repetition of this operation (Wallach and Brass*).
A similar method is used by Schimmel and Co. for the prepara-
tion of large quantities of pure cineole, but in this case it is
obtained from the oil of Hucalyptus globulus, and not from the oil
of wormseed.

PROPERTIES.—Cineole is a liquid which has a character-
istic odor resembling that of camphor, and is optically in-
active. The purest commercial product* boils at 176°, has
a sp. gr. 0.930 at 15°, and a refractive index, np = 1.45961,
at 17°. When cooled to a low temperature, it solidifies to
crystals, melting at — 1°; this property may be used for the
purification of cineole. According to Wallach, it has a refrac-
tive index, ng = 1.45590.°

It combines with concentrated phosphoric acid, forming the
compound, C,,H,,O-H,PO,, which may also be employed for the
preparation of pure cineole from eucalyptus oil. It also forms
addition-products with a- and $-naphthol and iodol.

It is not attacked by sodium, phosphoric chloride or benzoyl
chloride. It does not unite with hydroxylamine or phenylhy-
drazine. The oxygen atom in cineole is, therefore, combined{in a
position similar to that in which it occurs in ethylene oxide.

1Wallach, Ann. Chem., 239, 20; 275, 106.

2Bouchardat and Voiry, Compt. rend., 106, 663.
3Wallach and Brass, Ann. Chem., 225, 291.

4Schimmel & Co., Semi-Annual Report, April, 1895, 34.
5Wallach and Pulfrich, Ann. Chem., 245, 195.
6Scammel, German patent, No. 80,118.

CINEOLE HYDROBROMIDE. 325

Cineole is generally regarded as an anhydride of terpine :

3 ie

H
H, H, H, H,
H, 2 H,

AL

H
HC CH, - H,C CH,
Terpine. Cineole.

If we assume the correctness of the terpine formula, then the
above formula would represent the constitution of cineole; this
view is supported by the formation of cineole from terpine, and
by the general behavior of cineole. The dihydrochloride or di-
hydrobromide of dipentene is obtained when a glacial acetic acid
solution of cineole is saturated with hydrochloric or hydrobromic
acid. Dipentene dihydriodide is even formed when dry hydriodic
acid is passed through cold cineole, whilst under the same condi-
tions hydrochloric and hydrobromic acids combine with cineole,
forming addition-products (Wallach and Brass).

It is manifest, therefore, that cineole may be changed by the
action of acids in a manner similar to terpine and terpineol ; thus,
it is converted into terpinene and terpinolene by the action of
alcoholic sulphuric acid (Wallach’).

Cineole hydrochloride, (C,,H,,O),"HCl (?), was first obtained by
Volkel.2 It is prepared by treating a well cooled mixture of
light petroleum and cineole with dry hydrochloric acid gas (Wal-
lach and Brass).

It is readily soluble in terpenes, hence it is not suitable for the
detection of cineole in ethereal oils. Its behavior towards water
has already been mentioned. It decomposes into water, hydrogen
chloride and dipentene when dry distilled (Wallach and Brass).

Simultaneous with the researches of Wallach and Brass, a de-
tailed investigation of cineole was carried on by Hell and Ritter ;*
according to these chemists, the hydrochloride has the formula,
C,,H,,O°HCl.

Cineole hydrobromide, C,,H,,(OH)Br, was obtained in an im-
pure condition by Hell and Ritter ;* it was also prepared by Wal-
lach and Brass.

In order to prepare it, cineole is dissolved in petroleum ether,

1Wallach, Ann. Chem., 239, 22.

2Vélkel, Ann. Chem., 87, 315.

3Hell and Ritter, Ber., 17, 1977. .
4Hell and Ritter, Ber., 17, 2610.

326 THE TERPENES.

and the solution, well cooled by a freezing mixture, is treated with
dry hydrogen bromide, which at once produces a white precipi-
tate; this is filtered, washed with petroleum ether and dried. It is
rather more stable than the hydrochloride, and melts at 56° to 57°.
Since it is very sparingly soluble, the presence of cineole in mixtures
of terpenes may be recognized by the formation of the hydrobro-
mide ; this reaction is so sensitive that one per cent. of cineole in
limonene may be readily detected (Wallach and Gildemeister).

Cineole hydrobromide is decomposed by water into pure cineole
and hydrobromic acid.

Cineole combines with the halogens, yielding unstable, additive
products.

Cineole dibromide, C,,H,,O-Br,, is obtained in red needles if
bromine be added to a cold solution of cineole in petroleum ether
(Wallach and Brass). It easily decomposes on keeping. If
crystals of the dibromide are placed in closed vessels and kept in
a cool place for some time, they decompose with elimination of
water and formation of an oil, which partially solidifies to a crys-
talline mass and yields dipentene tetrabromide on recrystallization ;
the same tetrabromide may also be produced in considerable
quantities by treating the admixed oil with alcohol and bromine.

Cineole diiodide, C,,H,,O-L,, is likewise prepared by the action
of iodine on a solution of cineole in petroleum ether; it crystal-
lizes in long, dark needles, which are more stable than those of
cineole dibromide (Wallach and Brass).

Addition-product of cineole and iodol,’ C,,H,,O-C,I,NH, is well
adapted for the rapid detection and isolation of cineole in vola-
tile oils. A small quantity of iodol, C,I,NH, is dissolved in a
few drops of the oil under investigation, using a moderate heat ;
if cineole be present, the addition-product soon separates in the
form of yellowish-green crystals. It may be recrystallized from
alcohol or benzene, and melts at 112°. It is very sparingly
soluble in petroleum ether. It is decomposed by sodium hydrox-
ide, with regeneration of cineole.

CINEOLIC ACID, C,,H,,0,.

Cineole is oxidized by potassium permanganate, yielding cine-
olic acid, oxalic acid, acetic acid and carbonic acid (Wallach and
Gildemeister*). The preparation of small quantities of racemic
cineolic acid is best accomplished by the method described by
the above-mentioned chemists. Large quantities are obtained by
the following process.

1Hirschsohn, Pharm. Zeitschr. f. Russl., 32, 49 and 67; Bertram and

Walbaum, Archiv. d. Pharm., 235, 178.
2Wallach and Gildemeister, Ann. Chem., 246, 265.

ETHYL HYDROGEN CINEOLATE. 327

One hundred ce. of cineole are mixed with a solution of 420
grams of potassium permanganate in 6.3 liters of water, and
the mixture is placed in a double-walled, metallic vessel, which is
connected with an upright condenser. The vessel is so constructed
that steam may be passed, during the entire operation, between the
outer and inner walls. It is then vigorously agitated on a shak-
ing-machine for about three and one-half hours, or until the color
of the permanganate solution is removed. The manganese oxides,
which separate, are filtered off, and the filtrate is evaporated to
dryness ; the residue, consisting of the potassium salt of cineolic
acid, is extracted with alcohol in which it is readily soluble, and
the free acid is precipitated from the alcoholic solution by the ad-
dition of dilute sulphuric acid. The crude acid is freed from ad-
mixed potassium sulphate by dissolving in ether, and, on evapora-
tion of this solvent, is recrystallized from twenty times its amount
of boiling water. The yield is forty-five per cent. of the weight
of cineole employed.

Pure cineolic acid separates from water in colorless, well de-
fined crystals, which often appear as twins ; it is optically inactive,
and melts' and decomposes at 196° to 197°. It is soluble in
seventy parts of water at 15°, and in about fifteen parts of boil-
ing water. It is readily soluble in aleohol and ether, more spar-
ingly in chloroform. By means of its strychnine salt it is resolved
into the optically active cineolic acids.’

The following compounds are derivatives of racemic cineolic
acid.

Calcium cineolate, C,,H,,O,Ca + 4H,0O, is characteristic. If a
cold aqueous solution of the acid be saturated with calcium car-
bonate and then filtered, calcium cineolate separates from the
filtrate on boiling. It is insoluble in boiling water.

Silver cineolate is rather easily soluble in alcohol and water.

Methyl cineolic ester,? C,H,,O(COOCH,),, is obtained by satu-
rating a methyl alcoholic solution of cineolic acid with hydro-
chloric acid gas. It melts at 31°.

Ethyl cineolie ester, C,H,,O(COOC,H,),, is prepared in an
analogous manner to the preceding compound. It is a colorless
liquid, boiling at 155° under a pressure of 11 mm. to 12 mm.

Ethyl hydrogen cineolate,*

H
C,H,,0
C,H,

1 According to Rupe and Ronus (Ber., 33, 3544), pure, inactive cineolic
acid melts at 204° to 206°.

2Wallach, Ann. Chem., 258, 319.

sRupe, Ber., 33, 1133.

328 THE TERPENES.

crystallizes from dilute alcohol in slender needles, and melts at
99° to 100°.

Cineolic anhydride,’ C,,H,,O,, is produced when cineolic acid is
heated with several times its weight of acetic anhydride until all
of the acid is dissolved. The excess of acetic anhydride and
acetic acid is then distilled off under diminished pressure, and on
continuing the distillation cineolic anhydride is obtained ; it boils
at 157° under 12 mm. to. 13 mm. pressure, and when pure melts
at 77° to 78°. It is readily soluble in chloroform or benzene,
and crystallizes from a mixture of petroleum ether and benzene
in long needles ; it is reconverted into cineolic acid by boiling
water.

Cineolic acid amides are produced by the action of one molec-
ular proportion of anhydrous organic bases on one molecule of
cineolic anhydride (Wallach and Elkeles').

Cineolic piperidide,

results when an ethereal solution of the anhydride is treated with
piperidine ; it crystallizes in colorless needles by the slow evapo-
ration of the solvent, and melts at 151° to 152°. It forms a
sparingly soluble silver salt of the composition AgOOC-C,H,,O--
CONC,H,,.

Cineolic allylamide,

is sparingly soluble in ether, crystallizes from a mixture of methyl
alcohol and ether, and melts at 126°.
Cineolic diethylamide,
ide 9 ON (Cas)
*™\cooH
melts at 162° to 163°.
Cineolic anilide,
CoO ont

is obtained as a syrup, which may be converted into a silver salt ;
this reacts with methyl iodide, yielding a methyl ester which melts
at 78° to 79°.

CONHC,H;

lWallach and Elkeles, Ann. Chem., 271, 21.

—— =
—— 2 ——

CINEOLIC PHENYLHYDRAZIDE. 329

Cineolic para-toluidide,
CONHC,H,CH.
C.Hy, 0g 6*"4 3
COOH
separates from a mixture of ether and methyl alcohol in well
defined crystals, melting at 125° to 126°.
Cineolic phenylhydrazide,
CONH: ae
C,H, 40 \co

crystallizes in needles, and melts at 110°.

When cineolic anhydride is subjected to dry distillation, it is
quantitatively decomposed into carbonic oxide, carbonic anhydride,
and methyl hexylene ketone :—

C,oH,,0, = CO + CO, + C,H,,0.

Wallach regards as the probable explanation of this reaction,
that a saturated, but unstable, oxide is at first formed, which then
suffers an intramolecular change and is converted into an unsatu-
rated ketone. Such a transformation would be analogous to that
which is known to take place in the formation of pinacoline. The
following formulas ' illustrate this change :

is f eS

Le H.
H, CH, H, | COOH ?
H, H, _ H, a) _ H,
A H a
H, CH; H; 3 H,C CH,
Cineole. Cineolic acid. Cineolic anhydride.
} d
Ne
1,6 | i
H, i = oH, CH,—-00-CH,
Hs
H
H,; CH,
Oxide (hypothetical ). Methyl hexylene ketone.

‘For more recent formulas of cineole and cineolic acid, see Wallach,
Ann. Chem., 291, 350.

330 THE TERPENES.

Methyl hexylene ketone (methyl heptenone), C,H,,O, is a liquid,
having an agreeable odor like that of amyl acetate; it boils at
173° to 174°, has a refractive power, ng= 1.44003, and specific
gravity of 0.8530 at 20°. According to Schimmel & Co., it
boils at 170° to 171° (758 mm.), has the sp. gr. 0.858 and re-
fractive index, np= 1.44388, at 15°. It unites readily with
bromine, and is decomposed by permanganate. It does not
decolorize a sulphurous acid solution of fuchsine, but forms an
unstable additive compound with acid sodium sulphite, and com-
bines with phenylhydrazine and hydroxylamine, yielding an oily
hydrazone and oxime. Its semicarbazone’ melts at 136° to 138°.

Meta-dihydroxylene, C,H,,, is formed, together with a poly-
meride of this hydrocarbon, when methyl hexylene ketone is
heated with zinc chloride at 90° to 95°. This transformation is
probably expressed by the following equation :

H H
\ Va
CH CH, CH; Hi.
H; bu, = H,0+ H H,
?
HH, Js
Methyl hexylene ketone. Meta-dihydroxylene.

When meta-dihydroxylene is carefully treated with nitric acid,
it yields nitro-m-xylene.

Methyl hexylene ketone has recently become quite important
in consequence of its discovery in many ethereal oils, and because
of its relation to the aliphatic members of the terpene series. Its
constitution is completely explained by the researches of Tiemann
and Semmler, who made the important observation that methyl
heptenone is converted into acetone and laevulinic acid by oxidation.

For the various syntheses and methods of preparation of
methyl heptenone, and an enumeration of its derivatives, the
original publications * must be consulted.

An unsaturated alcohol,* methyl heptenol (methyl hexylene car-
binol), C,H,,OH, is formed, when methyl hexylene ketone is re-

1Tiemann and Kriiger, Ber., 28, 2124.

*Léser, Bull. Soc. Chim., 17 [III.], 108; Compt. rend., 127, 763; 128, 108;
Barbier and Bouveault, Compt. rend., 121, 168; 122, 393 and 1422; Bar-
bier and Léser, Bull. Soc. Chim., 17 [III.], 748; Barbier, Compt. rend.,
128, 110; Verley, Bull. Soc. Chim., 17 [III.], 175; Tiemann, Ber., 31, 2989;
82, 812 and 830; Tiemann and Semmler, Ber., 26, 2719 and 2721; 28, 2128;
Wallach, Ann. Chem., 319, 77.

3Wallach, Ann. Chem., 275, 171.

METHYL HEXYLENE OXIDE. 331

duced with sodium and alcohol. This alcohol is also obtained as
a decomposition product of geraniol, and further by the hydrol-
ysis of geranic nitrile. It boils at 174° to 176°, has a
sp. gr. of 0.850 and a refractive index, n, = 1.44889. When
this alcohol is boiled with dilute sulphuric acid, it is converted
into an isomeric, saturated oxide, C,H,,O. This reaction is quite
analogous to that by which the homologous alcohol, C,H,,OH,
obtained from methyl heptylene ketone, is converted into an
isomeric oxide, C,H,,O (see thujone).

Methyl hexylene oxide, C.H,,O, boils at 127° to 129°, has a
specific gravity of 0.850 and index of refraction, np = 1.4249.
It has an odor resembling that of peppermint and of cineole, and
is probably a homologue of the oxide, boiling at 78° to 83°, which
Perkin and Freer’ obtained from 7-pentylene glycol.

CH,—CH— CH,
CH,'CH(OH)°CH,’CH,’CH,(OH)=H,0+ 0g
CH,—CH,
y-Pentylene glycol. y-Pentylene oxide.
HH,
GH, H—CH—CH,
Ds esc oDag Ic A fa, OC
3
H, CH,—CH—CH,
Methyl hexylene carbinol. Methyl hexylene oxide.

Wallach and Elkeles also prepared methyl hexylene ketone by
the distillation of cineolic amides :—

CONHR
CHOC on —RNH,-+00+C0,+0,H,,0.

When cineolic acid is submitted to dry distillation, it is par-
tially converted into its anhydride, and partially into a liquid
monobasic acid, C,H,,O, (b. p. 185° under 11 mm.), together with
some methyl hexylene ketone :*—C,,H,,O, = CO, + C,H,,0,.

Wallach and Elkeles have described the methyl ester of this
monobasic acid, C,H,,O,; it is a liquid, boiling at 125° under a
pressure of 13 mm.

Wallach and Gildemeister obtained only oxalic acid and carbon
dioxide by the oxidation of cineolic acid with permanganate or
dilute nitric acid. These two products are also formed when —
cineole is oxidized with dilute nitric acid ; therefore, a relation-
ship between cineolic acid and terebic acid or terpenylic acid does
not appear to exist.

1 Perkin and Freer, Ber., 19, 2568; compare Lipp, Ber., 18, 3285; 19, 2843.
2Wallach, Ann. Chem., 246, 274; 258, 321; 271, 26; Rupe, Ber., 33, 1129.

332 THE TERPENES.

According to Rupe,’ when cineolic acid is heated with water at
160° for three hours, it yields a mixture of two isomeric acids,
C,H,,O,; one of these acids is termed a-cinenic acid, and the other
is called methoethylol-5-hexene-2-acid-6.

a-Cinenic acid, C,H,,O,, is stable towards potassium permanga-
nate, is not acted upon by bromine, does not react with phenyl-
hydrazine, hydroxylamine, or semicarbazide, and probably contains
a cyclic arrangement of the carbon atoms. It is a monobasic
acid, crystallizes from petroleum ether in transparent crystals,
melts at 83° to 84°, and boils at 127.5° to 129.5° (14 mm.) or at
245° to 247° under atmospheric pressure. It is soluble in most
organic solvents, readily soluble in hot, sparingly in cold, water ;
it is volatile with steam. It forms silver and calcium salts, and
methyl and ethyl esters. When a-cinenic acid is heated with water
in a closed tube at 160°, it is partially converted into methoethylol-
5-hexene-2-acid-6. When hydrochloric acid gas is allowed to
act upon the alcoholic solution of a-cinenic acid, without cooling,
ethyl-d-chloro-a-methoethylol-5-hexoate, C,H,,Cl(OH):COOC,H,, is
formed ; this ester boils at 131° to 136° (17 mm.), and is an
open-chain compound.

When a-cinenic acid is treated with a glacial acetic acid solu-
tion of hydrogen bromide, it yields 0-bromo-a-oxyisopropyl hexe-
noice acid, C,H,,Br(OH):COOH, which crystallizes in needles and
melts at 97° to 98° ; when the latter acid is treated with alcoholic
potash, it gives rise to methoethylol-5-hexene-2-acid-6, and when
treated with water, it forms cinogenic acid, C,H,,(OH),-COOH.
Cinogenic acid (d-oxy-a-oxyisopropyl hexenoic acid) is also one
of the products of the action of water under pressure on cineolic
acid ; it is insoluble in ether, crystallizes from chloroform in tablets
and melts at 104.5° to 105°; when distilled under diminished pres-
sure, or heated under pressure with water, it yields a-cinenic acid.

8-Cinenic acid, C,H,,O,, is formed by the action of sulphuric
acid on cineolic acid, and also by heating a-cinenic acid with
dilute sulphuric acid under pressure; it is stereoisomeric with
a-cinenic acid, and is possibly an example of cis- and trans-iso-
merism. It is a liquid acid, boiling at 122° to 123° (10 mm.),
has the refractive index, ny = 1.4486, and forms a characteristic
calcium salt, which crystallizes from water in needles; the corre-
sponding salt of a-cinenic acid is amorphous. -Cinenic acid may
be converted into cinogenic acid in the same manner as the a-acid.

Methoethylol-5-hexene-2-acid-6 (a-oxyisopropyl-4’-hexenoic acid),
C,H,,0,, is isomeric with the cinenic acids and is formed together
with a-cinenic acid by the action of water on cineolic acid.

1Rupe, Chem. Centr., 1898 [II.], 1055; Ber., 33, 1129; 34, 2191.

D- AND L-CINEOLIC ACIDS. 333

It crystallizes from water in small leaflets and from petroleum in
silky needles; it melts at 59° to 60°, and boils at 152° to 153°
(10 mm.). It decolorizes aqueous permanganate solutions, com-
bines directly with one molecule of bromine, and contains an
open-chain of carbon atoms. It is much more soluble in water
than a-cinenic acid, and forms silver and magnesium salts. This
acid is a f-oxy-acid, and when distilled under atmospheric pres-
sure, it loses one molecule of water, yielding a-iso-propylidene-
4-hexenoie acid (methoethene-5-hexene-2-acid-6), C,H,,O,; this
is a colorless, liquid acid, which boils at 136° to 138° (11 mm.),
has the sp. gr. 0.9816 at 17°, and gradually resinifies in the air.

By means of the strychnine salt, Rupe and Ronus’ have re-
solved cineolic acid into its optically active components. When
cineolic acid is dissolved in hot water and is treated with one
molecular weight of finely pulverized strychnine, the salts of the
two optically active and the inactive acids are obtained ; they are
separated by fractional crystallization. The strychnine salt of
dextro-cineolic acid, C,,H,,O,N,, separates first and may be re-
crystallized from hot water; it forms large prisms, which melt at
195° to 197°. On further evaporation, the mother-liquors of
the dextro-salt yield successively the salts of the inactive and levo-
cineolic acids.

The strychnine salts of the active cineolic acids are converted
into the free acids by treatment with dilute hydrochloric acid at
a temperature not exceeding 40°. The resulting dewtro- and levo-
cineolic acids are repeatedly crystallized from water in order to
free them (especially the levo-acid) from admixed racemic cineolic
acid. The optically active acids, C,,H,,0,-+ H,O, separate from
water in large, transparent crystals which contain one molecule of
water of crystallization, and melt at 79° ; the racemic acid never
crystallizes with water of crystallization, and is formed by crystal-
lizing a mixture of equal quantities of the two optically active
acids.

When the hydrated crystals of the active acids are exposed to
dry air, they lose their water, yielding anhydrous acids which
melt at 138° to 139°, and have the specific rotatory powers, [a] p
= + 18.56° and —19.10°. The racemic acid melts? at 204° to
206°.

The active acids are much more soluble in water and in chloro-
form than the racemic acid. On dry distillation they yield the
anhydride, methyl heptenone and other decomposition products.

1Rupe and Ronus, Ber., 33, 3541.
2 According to Wallach and Gildemeister, the inactive acid melts at 196°
to 197°.

334 THE TERPENES.

d-Cineolic anhydride, C,,H,,O,, is formed by the action of acetic
anhydride on d-cineolic acid ; it boils at 165° to 167° (15 mm.),
dissolves sparingly in petroleum ether, and crystallizes from
benzene in large tablets, melting at 108°. It has the specific
rotatory power, [a], = + 45.37°, at 20° in a benzene solution.

13, TERPAN-1, 4, 8-TRIOL, C,,H,,(OH),.

This compound has already been mentioned as an oxidation
product of Baeyer’s 4*®terpen-1l-ol (see page 273). Its con-
stitution may be regarded as proved by its transformation into
tribromoterpane, melting at 110°.

14. TRIOXYHEXAHYDROCYMENE, C,,H,,(OH),.

This substance melts at 121° to 122°. (Compare under ter-
pineol, page 262.)

15. PINOLE HYDRATE, C,,H,,0-OH.
This compound is described under pinole ; see page 276.

16, LIMONETROL, C,,H,,(OH),.

Limonetrol is prepared by the following method suggested by
G. Wagner.’

Five liters of a one per cent. solution of permanganate are
added drop by drop to a mixture of one liter of water and sixty-
five grams of limonene, the mixture being continually shaken.
When the reaction is complete, the product is filtered and the
precipitate, consisting of manganese oxides, is carefully washed
with water. The volatile compounds are removed from the fil-
trate by distillation with steam, and the residue is concentrated by
evaporation and extracted with ether. On evaporation of this
solvent, the resultant limonetrol is washed with a small quantity
of ether, and crystallized from alcohol; it separates in small,
lustrous needles. The yield is very good.

This tetrahydric alcohol is readily soluble in water, has a sweet
taste, and melts at 191.5° to 192°. |

17, PINOLE GLYCOLS, C,,H,,0(OH),.
These compounds are mentioned under pinole (see page 279).

The most important transformations of the various keto- and
oxy-hydrocymenes, in so far as they are not represented in the
tables given under terpineol, are shown in the accompanying table.

1G. Wagner, Ber., 23, 2315.

10
39 o"H"O
o"~"D (euoarvoorpAyeryoy,) oO" Hs
euoyueyl ae et - A a
HO"H"D HO"H") HO"HD
—poyyuey[<—_ —> [OYIUSMOALB) << joujueurefaqy,
Pee Nee < rhe
Yeprporspéy i [sareoorpéqiqg suofny}0s] <<
HON HO HO“H"9 HOH")
JOoAreoned1pAyid JooAavoorpAgrcy- yoqooye pAtnqy,
ras ee
y V |
‘Oo E"0 o"H"Dd oH") oH") oH") = o"H"D o"H") oH")

‘guousyuepy + ouoderng | eucAIvoNooIpAYIG, SUOUAAIE ~ gx QUOLL) ~<—eR auoAIvoOIpAYIC, | 1UOJIOVULJOATLD eg (QUOJOORU}) duOfNyT—

oH") o'H"9
—— FLO ALBONY: QUOALBY)

JououareD

KETO- AND OXY-HYDROCYMENES; TABLE OF.

HOR oe

‘SHNAWANOUGAPT-AXOQ ANV -OLAY AHL AO SNOLLVWHOASNVUT,

AMIDO-DERIVATIVES OF THE TERPENES.

I. BASES WHICH CAN NOT BE REGARDED AS DE-
RIVATIVES OF THE HYDROCYMENES.

(Analogues of Pinene, Camphene, Fenchene, and of Cam-
pholenic Acid and Fencholenic Acid.)

1, PINYLAMINE, C,,H,,NH,,.

Pinylamine is formed by the reduction of nitrosopinene, the
compound obtained by the action of alcoholic potash on pinene
nitrosochloride :—

C,>H,;NO + 4H = H,0 + C,oH,;NH,.

In order to prepare it, thirty grams of nitrosopinene are dis-
solved in about 200 cc. of warm glacial acetic acid ; the solution
is diluted with water until it commences to appear cloudy, and is
then treated with zinc dust, which is added in small portions at a
time. After the first violent evolution of hydrogen has abated,
the reaction is accelerated by adding water and heating the mix-
ture on the water-bath for several hours. The liquid is then
poured off from the zinc, which must always be present in excess,
and is diluted with a large amount of water; the zine is precipi-

tated from the hot solution by hydrogen sulphide, is filtered off,

and the filtrate concentrated on the water-bath until a dark
coloration appears. It is again filtered, and the sparingly soluble
pinylamine nitrate is precipitated by the addition of a hot, satur-
ated solution of sodium nitrate. It is crystallized from hot water.
The yield of pinylamine is approximately fifty per cent. of the
theoretical (Wallach and Lorentz’).

The free base is produced by treating pinylamine nitrate with
sodium hydroxide ; it is dried over potash, and distilled in vacuum.

1A series of papers has been published by P. Duden on “Synthetical bases
of the series of terpenes and camphors”; the following references are men-
tioned: Ber., 33, 481; Ann. Chem., 313, 25 and 59.

2Wallach and Lorentz, Ann. Chem., 268, 197; compare Ann. Chem., 258,
346, and Ber., 24, 1549.

336

ee, Oo

Pe mI Nm ore He =

ACETYL PINYLAMINE. 337

When freshly distilled, it is a thick, colorless oil, which boils at
207° to 208° under ordinary pressure, and at 98° to 99° under
22 mm. to 23 mm. It may be kept unchanged in a sealed vessel,
but in the air it soon decomposes with liberation of ammonia; it
also takes up carbonic anhydride from the air. It is almost in-
soluble in water, but dissolves freely in alcohol, ether and chloro-
form. It has a strong basic smell, resembling that of borneol.
Its specific gravity at 17° is 0.943. Pinylamine is an unsaturated
compound,

Pinylamine hydrochloride, C,,H,,NH,-HCl, is precipitated from
an ethereal solution of the amine by hydrochloric acid gas, and
crystallizes from water in thin needles, melting at 229° to 230°.
If this salt be heated above its melting point, it is very readily
decomposed into ammonium chloride, cymene, and a_ small
quantity of a compound which appears to unite with oxygen in
the air, and has the composition, C,,H,,O; this oxygenated com-
pound yields an oxime when treated with hydroxylamine. The
decomposition of pinylamine hydrochloride is represented by the
equation :—C,,H,.NH,-HCl = NH,Cl + C,,H,,.

Pinylamine platinochloride, (C,,H,.N-HCl),PtCl,, is sparingly
soluble in water, but freely in alcohol; it decomposes without
melting when heated above 200°.

Pinylamine nitrate, C,,H,,NH,HNO,, is difficultly soluble in
water. It crystallizes from dilute alcohol in long, colorless
needles.

Pinylamine sulphate, (C,,H,,NH,),-H,SO,, forms small needles,
and decomposes above 200° without melting.

Pinylamine thiocyanate, C,,H,,NH,-HCNS, is obtained, when
the aqueous solutions of equal molecular proportions of pinylamine
hydrochloride and potassium thiocyanate are mixed, allowed to
evaporate, and the residue is extracted with alcohol. It crystal-
lizes from water in well defined prisms, and melts at 135° to
136°.

Pinylamine oxalate, (C,,H,,NH,),H,C,O,, separates at once in
the form of brilliant crystals, if a concentrated aqueous solution
of one molecular proportion of oxalic acid be added to a dilute
alcoholic solution of two molecules of pinylamine. It melts
without decomposition at 247° to 248°, and dissolves sparingly
in all ordinary solvents.

Pinylamine picrate forms yellow needles, and is slightly soluble
in cold water.

Acetyl pinylamine, C,,H,,NH-COCH,, is prepared by heating
pinylamine with acetic anhydride. It crystallizes from petroleum
ether or alcohol, and melts at 108° to 109°.

22

338 THE TERPENES.

Benzoyl pinylamine, C,,H,,NH-COC,H,, is best obtained by the
action of one molecule of benzoyl chloride on an ethereal solution
of two molecular proportions of pinylamine; some pinylamine
hydrochloride separates during the reaction, and is filtered off.
The ethereal solution is evaporated, and the resulting benzoyl
compound is washed with ammonia, and crystallized from glacial
acetic acid or petroleum ether; it separates in small needles,
melting at 125°.

Pinyl carbamide, C,,H,,NH:CO-NH., is produced by treating
pinylamine hydrochloride with potassium cyanate ; it crystallizes
in long, colorless needles, and melts at 156°.

Benzylidene piny lamine, C,,H,,N = CH:C,H,, results on mixing
equal molecular weights of pinylamine and benzaldehyde; the
mixture becomes warm, and the reaction takes place with elimina-
tion of water. It crystallizes from alcohol in splendid crystals,
melts at 52° to 53°, and decomposes on keeping.

Furfuro-pinylamine, C,,H,,N = CH-C,H,0O, is the condensation-
product of pinylamine and furfural ; it separates from alcohol in
well formed crystals, and melts at 80° to 81°.

o-Oxybenzylidene pinylamine, C,,H,,N = CH-C,H,OH, forms
lustrous, yellow crystals, and melts at 108° to 109°.

The halogen alkyls react vigorously with pinylamine.

Pinocarveol,’ C,,H,,OH, is formed when pinylamine is heated
with a solution of sodium nitrite. Since this is a secondary
alcohol, the following formula of pinylamine, originally proposed
by Wallach, does not represent the facts :

Hs

H
u,6 on,

2. AMIDOTEREBENTENE, C,,H,,NH,.

Pesci and Betelli? also converted pinene into an amine,
C,,H,,NH,, which is isomeric with pinylamine. It is obtained
from nitroterebentene.

1Wallach, Ann. Chem., 277, 149; Wallach and Smythe, Ann. Chem., 390,

286.
2Pesci and Betelli, Gazz. Chim., 16, 337; Jahresb. Chem., 1886, 613.

ai
- —

ae

es «a

Ea ee

‘

PINENE PHTHALAMIC ACID. 339

Nitroterebentene, C,,H,,NO,, is obtained by treating French or
American * oil of turpentine (levo- or dextro-pinene) with nitrous
acid. A seventy-five per cent. aqueous solution of 135 parts of
potassium nitrite is gradually added to a cold mixture of 100
parts of the terpene and 545 parts of dilute sulphuric acid (145
parts of concentrated acid to 400 parts of water), the mixture
being well shaken ; a green oil is formed, and is separated by the
addition of an excess of water. This product is shaken with
ammonia, and purified by fractional distillation with steam (Pesci
and Betelli’).

It is a yellow liquid, having an odor of peppermint, and is
readily decomposed on heating.

Amidoterebentene is prepared by reducing nitroterebentene with
zine dust and glacial acetic acid. It is an oil, having an agree-
able odor, and boils at 197° to 200°, undergoing slight decom-
position ; it boils without decomposition at 94° to 97° underfa
pressure of 9 mm. (Pesci and Betelli).

Amidoterebentene hydrochloride, C,,H,,NH,° HCl, obtained from
either levo- or dextro-pinene, is optically levorotatory,' [a], = —
48.5°. It crystallizes in rectangular tablets, having a mother-of-
pearl luster. The platinum salt forms hexagonal plates, is insoluble
in cold water, and is decomposed by boiling water. The sulphate
separates in a gelatinous, hygroscopic mass. The oxalate is ob-
tained in sparingly soluble leaflets.

Pinene phthalimide,

CHK NO ath

prepared by Pesci*® by the action of phthalic anhydride on amido-

terebentene, melts at 99° to 100°. It is insoluble in water, read-
ily soluble in alcohol, ether, and chloroform, and has the specific
rotatory power, [a], == — 35.38°. The potassium salt of pinene
phthalamic acid is formed by dissolving pinene phthalimide in a
hot solution of potash ; it crystallizes in thin needles.

Pinene phthalamic acid,

O00
CoH
CONHC,,H,,
results by decomposing its potassium salt with hydrochloric acid.
1Pesci, Gazz. Chim., 18, 219; Jahresb. Chem., 1888, 899.

2Pesci and Betelli, Gazz. Chim., 16, 337; Jahresb. Chem., 1886, 613.
3Pesci, Gazz. Chim., 21 (1.), 1; Chem. Centr., 1891 (I.), 542.

340 THE TERPENES.

It is recrystallized from chloroform, melts at 109° to 111°, and
is very unstable.

Trimethyl terebenthyl ammonium iodide, C,,H,,N(CH,).I, is pro-
duced by the interaction of methyl iodide and ‘amidoterebentene,
and crystallizes in rectangular leaflets. The chloride, prepared
from the iodide, is deliquescent, but yields a platinum salt which
is nearly insoluble (Pesci and Betelli).

3. BORNYLAMINES, C,,H,,NH,.

Bornylamine was discovered by Leuckart and Bach,’ who ob-
tained it by the treatment of camphor with ammonium formaie,
and also by the reduction of camphoroxime with sodium and alco-
hol. It was later made the subject of a detailed investigation by
Wallach and Griepenkerl.?

It is best prepared by the method proposed by Leuckart and
Bach and subsequently modified by Wallach and Griepenkerl.
An intimate mixture of not more than four grams of camphor
and the same weight of ammonium formate is heated at 220° to
230° for five hours. The reaction-product forms a syrupy mass
consisting chiefly of formyl bornylamine, together with some free
bornylamine, unchanged camphor, and ammonium salts, and solidi-
fies when shaken with cold water. It is boiled with alcoholic potash
for five or six hours, and the resulting bornylamine and camphor
are distilled over with steam. The distillate is acidified with
hydrochloric acid, filtered, concentrated and shaken with ether to
remove impurities which may be present in the solution. The
base is then set free by potash, extracted with ether, and the
ethereal solution dried with potassium hydroxide ; the ether is dis-
tilled off, and the bornylamine rectified, being careful to keep the
receiver well cooled on account of the extreme volatility of the
base. The yield is about eighty to eighty-two per cent.

Bornylamine melts at 159° to 160°, boils at 199° to 200°, and
dissolves very easily in alcohol and ether. It has an intensive
basic odor resembling that of camphor and piperidine ; it sublimes
at the ordinary temperature, and unites readily with carbonic
anhydride in the air. It is optically active, a 12.5 per cent. solu-
tion having a specific rotatory power of [a] >= — 18° 35’ 41”
(Leuckart and Bach).

Bornylamine hydrochloride, C,,H,,NH,-HCl, is precipitated in

the form of small, white needles when hydrogen chloride is passed
into an ethereal solution of bornylamine. When the hydrochloride

1Leuckart and Bach, Ber., 20, 104.
2Wallach and Griepenkerl, Ann. Chem., 269, 347.

BENZOYL BORNYLAMINE. 341

is dissolved in water or alcohol, it suffers partial decomposition.
It sublimes undecomposed in splendid needles without the forma-
tion of ammonium chloride and camphor.

The platinochloride, (C,,H,,NH,-HCl),PtCl,, dissolves readily in
hot water and alcohol, and forms golden-yellow scales.

Bornylamine hydrobromide,! C,,H,,NH,"HBr, separates as a
colorless, crystalline precipitate on the addition of bromine to an
ethereal bornylamine solution. It combines with bromine, form-
ing an unstable, red product.

Bornylamine acid sulphate,’ C,,H,,NH,-H,SO,, is prepared from
the theoretical quantities of dilute sulphuric acid and bornylamine ;
it separates in orthorhombic tablets on evaporation of the solution.
Like the hydrochloride, its aqueous solution is decomposed by
boiling.

Bornylamine tartrate, C,,H,,NH,C,H,O, + H,O, is easily solu-
ble in water, almost insoluble in cold alcohol, and crystallizes
from hot alcohol in needles.

Bornylamine picrate,' C,,H,,NH,-C,H,NO,),OH, forms golden-
yellow needles, which are almost insoluble in ether.

Bornylamine is very readily converted into the carbylamine de-
rivative.”

When bornylamine or its formyl compound is heated at 200°
to 210° with acetic anhydride, it is decomposed into camphene,

te
C,,H,,, and ammonia :

C,,H,,NH, = CyoHig +N Hs.

Formyl bornylamine,’ C,,H,,NH-CHO.—It has already been
mentioned that this compound forms the chief constituent of the
reaction-product produced by the action of ammonium formate on

camphor ; it may also be prepared by the action of formic acid on
the free base. When recrystallized from hot water, it forms white,
glistening scales, melting at 61°.

Acetyl bornylamine,’ C,,H,,NH-COCH,, is formed by the action
of acetyl chloride on an ethereal solution of bornylamine ; the
bornylamine hydrochloride, which at first separates, is filtered off,
the ethereal filtrate evaporated, and the resultant acetyl compound
crystallized from dilute aleohol. It forms leaflets, melting at 141°,
and is nearly insoluble in ligroine.

Benzoyl bornylamine, C,,H,,.NH-COC,H,, is prepared like the
preceding compound, and is similar to it in appearance and solu-
bility. It melts at 131°.

1Wallach and Griepenkerl, Ann. Chem., 269, 347.
2Leuckart and Bach, Ber., 20, 104.

342 THE TERPENES.

Bornylcarbamide,’ C,,H,,NH:CO-NH,, is formed from bornyl-
amine hydrochloride and potassium isocyanate. It crystallizes
in needles, which melt at 164°, and is readily soluble in hot
water and alcohol.

Methyl bornylearbamide,' C,,H,,NH:CO-NHCH,, results by
mixing the ethereal solutions of methyl isocyanate and bornyl-
amine. It melts at 200°.

Phenyl bornylearbamide,’ C,,H,,NH:-CONHC,H,, separates in
the form of silvery leaflets when phenyl isocyanate is added to an
ethereal solution of bornylamine. It melts and decomposes at
248°.

Bornyl phenylthiocarbamide,' C,,H,,NH:CS-NHC,H,, is pro-
duced from phenylthiocarbimide and the free base in an ethereal
solution ; it forms colorless needles, which melt at 170° and are
almost insoluble in petroleum ether. |

Dibornylthiocarbamide,? CS(NHC,,H,,),, is formed when the
dithiocarbamic acid salt, obtained by the interaction of carbon
bisulphide and bornylamine, is boiled for some time with ten to
fifteen times its weight of ninety-six per cent. alcohol. It sepa-
rates from alcohol in compact, transparent crystals, which melt at
223° to 224°.

According to Wallach and Griepenkerl,’ the alky] chlorides act
vigorously on bornylamine. When equal molecular quantities of
benzyl chloride and the free amine are heated at 140° to 150°
and the resulting product is treated with alkalis, a mixture of
bases is obtained which is fractionally distilled in vacuum ; the
following compound is thus isolated.

Benzyl bornylamine, C,,H,,NH-CH,C,H,, is a thick oil, boiling
at 184° under 14 mm. pressure. The hydrochloric acid salt
separates from water or alcohol in colorless crystals ; its platino-
chloride crystallizes in red, transparent prisms.

Benzyl bornylamine unites with methy] iodide, forming a meth-
iodide, which crystallizes from hot alcohol in thin needles, and is
very difficultly soluble in hot water.

Benzylidene bornylamine,’ C,,H,.N = CHOC,H,, is an oil; its
hydrochloride, which crystallizes in small needles, and its platino-
chloride have been analyzed.

{§ The other condensation-products of bornylamine with aldehydes
are liquids.

Bornylamine is very stable towards fuming nitric acid (wa
lach and Griepenkerl’).

l1Leuckart and Bach, Ber., 20, 104.
2Wallach and Griepenkerl, Ann. Chem., 269, 347.

DIBORNYLAMINE NITRITE. 343

When formyl bornylamine is oxidized with an acetic acid solu-
tion of chromic anhydride, it yields bornylamine and small quan-
tities of a very volatile compound, which melts at 159°, and con-
tains oxygen but no nitrogen; it appears to have the empirical
formula, C,,H,,O or C,,H,,O. A compound having the same
melting point has also been observed by Lampe' in the decompo-
sition of bornylamine nitrite.

Dibornylamine, (C,,H,,),NH, is obtained in a yield of about
nine per cent. from the product of the action between camphor
and ammonium formate (Wallach and Griepenkerl’). It remains
in the residue from the distillation of bornylamine with steam,
and is obtained as an oil which slowly solidifies ; it may be puri-
fied by distillation in vacuum.

Dibornylamine boils at 180° to 181° under a pressure of 12
mm., and erystallizes from alcohol in lustrous plates, melting at
43° to 44°,

Dibornylamine hydrochloride, C,,H,,N-HCl, is precipitated by
passing hydrochloric acid gas into an ethereal solution of the
base. It crystallizes in needles or plates, dissolves sparingly in
cold, readily in hot, water and melts at 260° with partial decom-
position. Its platinochloride crystallizes in red needles.

Dibornylamine nitrate, C,,H,.N-HNO,, is sparingly soluble in
water; it is well adapted for the separation of dibornylamine
from bornylamine.

A compound, C,H,,N-HBr-Br,, is formed when bromine is
added to a solution of dibornylamine in petroleum ether. It is
almost insoluble in ether and ethyl acetate, but crystallizes from
alcohol in stable, golden-yellow plates, which melt at 184°.

Dibornylamine nitrite, C,,H,,N-HNO.,, is rather sparingly soluble
_in water, but may be recrystallized unchanged from boiling
alcohol.

On boiling with acetic anhydride, dibornylamine forms a com-
pound, which crystallizes from alcohol in lustrous plates, melts at
59°, and seems to be isomeric with dibornylamine.

According to more recent investigations by Forster,’ the bornyl-
amine prepared by heating camphor with ammonium formate at
220° to 240° or by reducing camphoroxime with sodium and
amyl alcohol is not an individual compound, but contains two
isomeric bases, C,,H,.NH,. One of these melts at 163°, is
dextrorotatory, [a4], = + 45.5°, and is termed bornylamine, whilst
the other melts at 180°, is levorotatory, [a], = — 31.3°, and is

1Lampe, Inaug. Diss., Gittingen, 1889, 41.
2Wallach and Griepenkerl, Ann. Chem., 269, 347.
3Martin O. Forster, Journ. Chem. Soc., 73, 386; 75, 934 and 1149.

344 THE TERPENES.

ealled neobornylamine. (Leuckart and Bach’s “ bornylamine ”
melts at 159° to 160°, and is levorotatory, [4] = — 18.6°.)

Although bornylamine melts lower than neobornylamine, all its
derivatives possess a higher melting point than those of the
isomeride. The derivatives of bornylamine are also less
readily soluble than those of the levorotatory base, and this
property is employed in effecting the separation of the two iso-
merides.

The preparation of the two isomerides is accomplished as fol-
lows. Seventy-five grams of camphoroxime, dissolved in 750 cc.
of amy] alcohol, are treated in a reflux apparatus with seventy-
five grams of sodium ; the process requires about four hours, after
which 100 ec. of amyl alcohol are added. The reaction-mixture
is then treated with 450 cc. of water, and the same volume of
concentrated hydrochloric acid; the amyl alcohol is finally re-
moved by distillation with steam, and on allowing the aqueous
residue to cool, the hydrochlorides of the two amines crystallize
rapidly in lustrous needles. The yield is practically quanti-
tative.

The separation of the two isomeric bases is based on the greater
solubility in water of the hydrochloride of neobornylamine. The
free bases are obtained by decomposing the hydrochlorides with
caustic soda. About sixty per cent. of the product obtained on
reducing camphoroxime as above described consists of the dextro-
rotatory bornylamine, and forty per cent. is the levo-neobornyl-
amine.

Bornylamine, C,,H,,NH,, is a white volatile solid, melting at
163°; it somewhat resembles camphor, having a faint, pungent
odor like that of piperidine. It dissolves very readily in cold
organic solvents, but is insoluble in water (Forster).

Neobornylamine, C,,H,,NH.,, closely resembles its isomeride, but
remains as a powder after being kept in a desiccator, which treat-
ment causes bornylamine to become more camphor-like in con-
sistence ; it melts at 180°. It is insoluble in water, but more
freely soluble in organic solvents than bornylamine.

Many derivatives of the two bases have been prepared and
carefully studied by Forster. The most important of these are
given in the accompanying table, which shows the differences in
melting points of the derivatives of Forster’s bornylamine and
neobornylamine, and Leuckart and Bach’s bornylamine; the latter
may be regarded as a mixture of neobornylamine with about
twenty per cent. of the dextro-bornylamine.

For the “influence of substitution on specific rotation in the
bornylamine series,” and the “influence of an unsaturated link-

345

f bornylamine,”

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DERIVATIVES OF BORNYLAMINE; TABLE OF,

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346 THE TERPENES.

4, CAMPHYLAMINES, C,H,,CH,NH,.

a-Camphylamine is produced by the reduction of the nitrile of
a-campholenic acid (camphoroxime anhydride) :—

C,H, ,CN+4H=C,H,,CH,NH,.

The reduction may be accomplished by zine and alcoholic hy-
drochloric acid (Goldschmidt and Koreff'), or by sodium and
alcohol (Goldschmidt*). Goldschmidt and Schulhof,? who made
a special study of camphylamine, employed the last-mentioned
method for its preparation.

a-Camphylamine‘* is a colorless liquid, boiling at 194° to 196°,
and has a strong basic odor; when exposed to the air, it combines
with carbon dioxide and solidifies to a waxy mass. In a one
decimeter tube, [a], = + 6°.

a-Camphylamine hydrochloride,’ C,,H,,N-HCl, forms colorless,
thin, orthorhombic plates ; it is readily soluble.

a-Camphylamine platinochloride,’ (C,,H,,N),H,PtCl,, crystallizes
in brilliant, yellow leaflets, which decompose without melting when
heated above 200°. The mercurtochloride? forms lustrous, ortho-
rhombic plates. ;

Acid a-camphylamine oxalate, C,,H,,N-C,O,H,+4H,O, is pre-
cipitated when a solution of camphylamine hydrochloride is
treated with a solution of oxalic acid ; it separates in colorless,
lustrous, orthorhombic crystals, and melts with decomposition at
194°.

a-Camphylamine sulphate, (C,,H,,N),H,SO, + H,O, crystallizes
in orthorhombic prisms, which are readily soluble. It cannot be
recrystallized from hot water without decomposition.

a-Camphylamine dichromate, (C,,H,,N),H,Cr,O,, is precipitated
from a solution of camphylamine hydrochloride by potassium
dichromate.

a-Camphylamine picrate forms slender, yellow needles, and melts
with decomposition at 194°.

Benzoyl a-camphylamine, C,,H,,NH-COC,H,, is obtained when
an ethereal solution of camphylamine is treated with benzoyl
chloride. Some camphylamine hydrochloride separates and is
filtered off; the ethereal filtrate is evaporated, and the residue
consisting of the benzoyl compound is washed with a soda solution,

1Goldschmidt and Koreff, Ber., 18, 1632.
2Goldschmidt, Ber., 18, 3297.
3Goldschmidt and Schulhof, Ber., 19, 708.
‘Tiemann, Ber., 29, 3006.

a

FENCHYLAMINE. 347

and crystallized from ligroine. It separates in colorless prisms,
melting at 75° to 77°.

a-Camphyl phenylthiocarbamide, C,,H,,NH-CS:-NHC,H,, is pre-
pared by the action of phenylthiocarbimide on an ethereal solution
of the base; it is crystallized from ligroine, and recrystallized
from ether. It separates in compact, colorless, lustrous prisms,
melts at 118°, and is readily soluble in alcohol and benzene,
more sparingly in ether, and very difficultly in ligroine.

a-Camphylamine dithiocamphylcarbamate,' C,,H,.NH-CS:‘SNH,--
C,,H,,, is obtained by the action of carbon bisulphide on cam-
phylamine.

a-Camphyl thiocarbimide” is formed in small quantity when
the preceding compound is boiled with a solution of mercuric
chloride.

a-Camphylamine reacts with ethyl iodide even in the cold, and,
like bornylamine, it gives the isonitrile feaction.

p-Camphylamine,’ C,,H,,NH,, is produced by the reduction of
f-campholenonitrile, C,H,,CN, in alcoholic solution with sodium.
It is optically inactive, and boils at 196° to 198°.

5. FENCHYLAMINE, C,,H,,NH..

Wallach* obtained this compound by treating fenchone with
ammonium formate, and also by reducing fenchonoxime with
sodium and alcohol.* Like fenchone, fenchylamine is known in
two optically active modifications having opposite rotatory powers,
as well as in an inactive form; the derivatives of the racemic
modification differ from those of its active components in melting
point and in solubility. A detailed investigation of dextrorotatory
fenchylamine and its derivatives was carried out by Wallach,
Griepenkerl and Liihrig.°

In order to prepare fenchylamine by the ammonium formate
method, five grams of pure fenchone are heated with an equal
weight of ammonium formate at 220° to 230° for six hours. The
resultant solid product contains unchanged fenchone, fenchylamine,
formyl fenchylamine (the chief product) and ammonium salts.
The fenchone is removed by distilling the acidulated reaction-
product with steam. The formyl derivative remaining in the
residue is saponified by boiling with concentrated hydrochloric

1Goldschmidt and Schulhof, Ber., 19, 708.

2Tiemann, Ber., 30, 242.

3Wallach, Ann. Chem., 263, 140.

4Wallach, Ann. Chem., 272, 105.

5Wallach, Griepenkerl and Liihrig, Ann. Chem., 269, 358.

348 THE TERPENES.

acid, and fenchylamine hydrochloride is obtained on the evapora-
tion of the hydrochloric acid solution; the free base results by
decomposing the hydrochloride with potash. The yield of fenchyl-
amine is about ninety per cent. of the theoretical.

For the preparation of fenchylamine from fenchonoxime,’
twenty-five grams of sodium are added rather rapidly to a so-
lution of twenty-one grams of the oxime in 100 ce. of absolute
alcohol. Any undissolved metal is brought into solution by a
further addition of alcohol, and the product is then distilled in a
current of steam. The resulting amine is dried over potash, and
rectified at ordinary pressure.

Fenchylamine boils at 195°, and has the specific gravity of
0.9095 at 22°; it has an odor resembling that of piperidine and
of bornylamine. It absorbs carbonic anhydride from the air,
forming solid fenchylamine fenchyl carbamate.?

Fenchylamine hydrochloride, C,,H,,NH,HCl, dissolves in water
and alcohol, and by slow crystallization i is obtained in transparent
prisms. It is readily soluble in ether.

The platinochloride, (C,,H,,NH,),H,PtCl,, crystallizes from
water in long, thin, hydrated prisms, which effloresce when kept
over sulphuric acid.

The hydriodide is also rather soluble in water and dilute alcohol,
and separates in well defined crystals. The nitrate is distinguished

by its great power of crystallization. Fenchylamine sulphate forms
needles or plates, which are only moderately easily soluble. The
picrate differs from bornylamine picrate in that it is readily
soluble in ether. The tartrate may be precipitated from an
aqueous solution by alcohol. The neutral oxalate is sparingly
soluble.

Fenchylamine nitrite, C,,H,.NH,-HNO,, is moderately stable,
readily soluble in water, and sparingly in a concentrated so-
dium nitrite solution; hence, small lustrous needles of fen-
chylamine nitrite are precipitated on the addition of a sodium
nitrite solution to a concentrated, neutral solution of a fenchyl-
amine salt.

Formyl fenchylamine,’ C,,H,,NH-CHO, is obtained by the action
of ammonium formate on fenchone ; it is also formed by the treat-
ment of fenchylamine with chloral. It crystallizes from dilute
alcohol in lustrous leaflets, and melts, for the most part, at 87°,
although some portions remain solid until the temperature rises
to 112°.

1Wallach, Ann. Chem., 272, 105.
2Wallach Griepenkerl and Ltihrig, Ann. Chem., 269, 358.
3Wallach, Ann. Chem., 263, 140.

ae a ae a

METHYL FENCHYLAMINE, 349

Acetyl fenchylamine,' C,,H,,NH-COCH,, is prepared by heating
the free amine with acetic anhydride ; it crystallizes from ether,
and melts at 98°. It is not very characteristic.

Propionyl fenchylamine,’ C,,H,,NH-COC,H,, melts at 123°.

Butyryl fenchylamine,’ C,,H,,NH-COC,H., melts at 77.5°.

Benzoyl fenchylamine,' C,,H,,NH-COC,H,, is produced by the
action of benzoyl chloride on an ethereal solution of the amine.
After evaporation of the ether, the syrupy residue is washed with
water which dissolves the fenchylamine hydrochloride formed in
the reaction. The resultant solid product is then dissolved in
aleohol, and the benzoyl compound is precipitated with dilute
sodium hydroxide, free benzoic acid being thus removed. It
melts at 133° to 135°.

Difenchyloxamide,| (CONHC,,H,,),, results on mixing oxalic
ester (one molecule) and fenchylamine (two molecules); it solidifies
after standing for some time. It crystallizes from alcohol in long
prisms or quadratic, thin plates, melting at 188°.

Fenchylearbamide,' C,,H,,NH-CONH,, is prepared by boiling
the solution of equal molecular proportions of fenchylamine hydro-
chloride and potassium isocyanate; it separates from the cold
solution in small needles, melting at 170° to 171°.

Fenchyl phenylthiocarbamide,' C,,H,,NH:CS:NHC,H,, is formed
when the dilute ethereal solutions of equal molecules of fenchyl-
amine and phenylthiocarbimide are mixed ; the reaction is rather
violent. This compound is especially well adapted for the
characterization of fenchylamine ; it is sparingly soluble in cold
alcohol and separates from this solvent in brittle, acute crystals,
while it is deposited from dilute solutions in colorless, brilliant,
well defined crystals, melting at 153° to 154°. Optically inactive
fenchyl phenylthiocarbamide melts at 169° to 170°.°

Difenchylthiocarbamide,' CS(NHC,,H,,),, is obtained when carbon
bisulphide is added to an ethereal solution of fenchylamine, and
the resultant dithiocarbamic acid salt is boiled with alcohol for a
short time. It separates from the cold solution in the form of
white leaflets, melting at 210°.

Methyl fenchylamine, C,,H,,NHCH,.—When an ethereal solu-
tion of fenchylamine is treated with methyl iodide, a mixture of
mono- and di-methyl fenchylamine hydriodides is produced and
gradually crystallizes from the ethereal solution. The two salts
may be readily separated by crystallizing from water in which the

1Wallach, Griepenkerl and Liihrig, Ann. Chem., 269, 358.

2Wallach and Binz, Ann. Chem., 276, 317; compare Zeitschr. fiir physik.
Chem., 12, 723.

3Wallach, Ann. Chem., 272, 105.

350 THE TERPENES.

salt of the mono-methyl base is more sparingly soluble than that
of the di-methyl derivative.

Mono-methyl fenchylamine, derived from its hydriodide, is an
oil of specific gravity 0.8950 at 20°; it boils at 201° to 202°,
has a refractive index, n, = 1.46988, at 20°, and is a weaker
base than fenchylamine. . Its hydrochloride forms prismatic crys-
tals, and is stable when exposed to the air; it is insoluble in
ether, whilst fenchylamine hydrochloride is easily soluble (method
of separation of fenchylamine and methyl fenchylamine).

Nitroso-methyl fenchylamine,

CH,
CdHyNC

o

is precipitated when a solution of methyl fenchylamine hydro-
chloride is treated with a solution of sodium nitrite ; it first forms
an oil which solidifies in the cold. It may be purified by dissolv-

ing in alcohol and precipitating with ice, and melts at 52° to 53°.

Benzyl fenchylamine,' C,,H,.NH-CH,C,H,, is prepared by boil-
ing the molecular proportions of fenchylamine and benzyl chloride
in a reflux apparatus for about one hour; benzyl fenchylamine
hydrochloride separates on cooling, is washed with ether to re-
move fenchylamine hydrochloride, and saponified with alkali. It
is a thick oil, boils at 190° to 191° at 16 mm. pressure, has a
feeble basic odor, and a sp. gr. of 0.9735 at 20°.

Its hydr ochloride and platinochloride form well defined crystals.

Nitroso-benzyl fenchylamine,

crystallizes from alcohol or ether in prisms, and melts at 93°.

Benzylidene fenchylamine,' C,,H,.N = CHC,H,, is formed with
development of heat and separation of water when the theoretical
quantities of fenchylamine and benzaldehyde are allowed to react.
On cooling, the reaction-product solidifies to a hard mass which
crystallizes from methyl alcohol in splendid needles, melting at
42°. Inactive benzylidene fenchylamine is obtained as an oil
by combing: equal amounts of the levo- and dextro-rotatory
modifications.”

The hydrochloride of the benzylidene derivative is hygroscopic,
and readily decomposes with formation of benzaldehyde.

1Wallach, Griepenkerl and Liihrig, Ann. Chem., 269, 358.
2Wallach, Ann. Chem., 272, 105.

ii. —

FENCHOLENAMINE. 351

Ortho-oxybenzylidene fenchylamine,' C,,H,,N = CHC,H,OH, re-
sults by gently warming salicylic aldehyde with fenchylamine ; it
crystallizes from alcohol in yellow needles, and melts at 95°.
Acids readily resolve this compound into its components. The
optically inactive derivative melts at 64° to 65°.

Para-oxybenzylidene fenchylamine,’ C,,H,,N = CHC,H,OH, is
prepared in an analogous manner to the preceding compound by
condensing p-oxybenzaldehyde with fenchylamine ; it melts at 175°.

Ortho-methoxybenzylidene fenchylamine,’ C,,H,,.N = CHC,H,O-
CH,, is produced by the condensation of fenchylamine and o-meth-
oxybenzaldehyde ; it melts at 56°.

Para-methoxybenzylidene fenchylamine melts at 54° to 55°.

Fenchylamine forms a solid condensation-product, C,,H,,NO,,
with aceto-acetic ester ; it has not been further investigated.

The following table contains the mean values obtained for the
specific and molecular rotatory powers of fenchylamine, prepared
from dextro-fenchone, and of its derivatives in chloroform solu-

tions (Wallach and Binz’).

Melting Point. [a]p [M]p
WEMCROHOMMIAG iacxs cee cessesea ccdccb sco seuss 165° +52,44° + 87.40°
DROW FOIE. 5.545.005 ic esiciesensercaresesse —24.89° — 38.00°
Formyl! fenchylamine.................-.+++ (114°) —36.56° — 66.04°
Acetyl fenchylamine............. .sessseeee 99° —46.62° — 90.73°
Propionyl fenchylamine....... ........+..+ 123° —53.16° —110.88°
Butyryl fenchylamine.................-06++ 77.5° —53.11° —118.19°
Benzylidene fenchylamine................. 42° +73.14° +175.90°
o-Oxybenzylidene fenchylamine......... 94° +66.59° +170.77°
p-Oxybenzylidene fenchylamine........ 175° +72.00° +184.65°
o-methoxybenzylidene fenchylamine... 56° -+59. 20° +160.09°
p-methoxybenzylidene fenchylamine... 55° +78.05° +211.07°

6. FENCHOLENAMINE, C,H,,CH,NH,.

A base of the composition, C,,H,,NH,, which bears the same
relation to camphylamine as fenchylamine to bornylamine, was
obtained by Wallach * by the reduction of fenchonoxime anhydride
(a-fencholenonitrile), C,H,,CN. This amine was carefully studied
by Wallach and Jenkel,* and designated as fencholenamine.

It is prepared by adding fifteen grams of sodium to a solution
of twenty-five grams of «-fencholenonitrile in one hundred and

1Wallach, Griepenker! and Liihrig, Ann. Chem., 269, 358.

2Wallach and Binz, Ann. Chem., 276, 317; compare Zeitschr. fiir physik.
Chem., 12, 723.

3Wallach, Ann. Chem., 263, 138.

4Wallach and Jenkel, Ann. Chem., 269, 369.

352 THE TERPENES.

twenty-five grams of absolute alcohol. Toward the end of the
reaction a small quantity of water is added, the liquid is heated
until all sodium is dissolved, and the product i is then poured into
water. After acidulating with sulphuric acid, the undecomposed
nitrile is distilled off in a current of steam, the free base is liber-
ated from the residue by means of sodium hydroxide, is separated
and fractionated in vacuum. The fencholenamine distills over at
110° to 115° under 21 mm. to 24 mm., while on continued dis-
tillation a small fraction is obtained at 115° to 147°, and then, at
147° to 148°, a base, C,,H,,NO, is obtained (see below).

Fencholenamine boils at 205° under atmospheric pressure ; it
readily absorbs carbonic anhydride, and is an unsaturated compound.

Fencholenamine nitrate, C,,H,,NH,HNO,, is formed by dis-
solving five grams of the base in eleven grams of nitric acid
of sp. gr. 1.105. It may be obtained in splendid crystals by re-
crystallization from twice its weight of water.

Fencholenamine sulphate, (C,,H,,N),"H,SO,, crystallizes in plates,
and is sparingly soluble in water, readily in dilute sulphuric acid.
Its aqueous solution is not decomposed by boiling.

Like an unsaturated amine, fencholenamine combines with two
molecules of hydrochloric acid. When hydrogen chloride is
passed into a methyl alcoholic solution of the base and the alcohol
is then allowed to evaporate, hydrochlorofencholenamine hydro-
chloride, C,,H,,CINH,-HCl, is obtained in well defined crystals.
This salt yields a fencholenamine containing only a small amount
of chlorine when it is treated with a solution of sodium hydroxide
in the cold.

Fencholenamine oxalate is sparingly soluble in water.

Acetyl fencholenamine, C,,H,,.NH-COCH,, is prepared by the
addition of acetic anhydride to an ethereal solution of the base.
It is a thick oil, and boils at 180° under a pressure of 21 mm.

Benzoyl fencholenamine, C,,H,,NHCOC,H,, is easily obtained
by the Schotten-Baumann method ; it melts at 88° to 89°.

The condensation-products of fencholenamine with aldehydes
are oils ; the compound obtained from furfural boils at 167° under
a pressure of 16 mm.

When fencholenamine is treated with nitrous acid, it is con-
verted into fencholeny] alcohol.

The above-mentioned base, C,,H,,NO, formed together with
fencholenamine by the reduction of a-fencholenonitrile, may be
easily separated from fencholenamine by means of its very soluble
oxalate. It boils at 147° to 148° under 21 mm. to 24 mm.
By boiling with dilute sulphuric acid, this amine loses water and
appears to be converted into fencholenamine.

CAMPHOLYL PHENYLTHIOCARBAMIDE. 353

7. CAMPHOLAMINE, C,H,,CH,NH,.

Campholamine is prepared by reducing campholonitrile,!
C,H,,CN, with sodium in alcoholic solution. (Campholic acid,
C,H,,COOH, is obtained by heating a solution of camphor in
benzene with sodium.)

This base is a colorless oil, lighter than water, and is only
slightly soluble in water. It boils at 210°, and quickly absorbs
carbonic anhydride from the air forming a crystalline salt
(Errera’).

Campholamine hydrochloride, C,,H,,N-HCl, is insoluble in ether,
and crystallizes from water in silvery lamine. The platino-
chloride separates from alcohol in yellow plates.

Campholamine nitrate, C,,H,,.N-HNO,, is sparingly soluble in
water, and may be recrystallized from boiling water. When
heated rapidly, the salt melts and decomposes at 220°.

Benzoyl campholamine, C,,H,, NH-COC,H,, is prepared by the
action of benzoyl! chloride on an ethereal solution of the base; it
is insoluble in water, readily soluble in the other ordinary sol-
vents, and melts at 98°. ,

Campholyl phenylthiocarbamide, C,,H,, NH-CS-NHC,H,, is pro-
duced by the action of phenylthiocarbimide on an ethereal solution
of the base, the reaction being energetic. When recrystallized
from dilute alcohol, it separates in colorless needles, melting at
117° to 118°; it is sparingly soluble in petroleum ether.

When a solution of campholamine hydrochloride is warmed
with silver nitrite, campholyl alcohol, C,,H,,OH, and a hydro-
carbon, C,,H,,, are formed. LErrera? terms this hydrocarbon,
campholene.

1Errera, Gazz. Chim., 22, I., 205; Ber., 25, 466, Ref.
2Errera, Gazz. Chim., 22, II., 109; Ber., 26, 21, Ref.

23

II. BASES WHICH MAY BE REGARDED AS DERIVA-
TIVES OF THE HYDROCYMENES.

A. AMINES, C,,H,,NH,, CONTAINING TWO ETHYLENE
LINKAGES.

1. CARVYLAMINES, C,,H,,NH,.

By the reduction of carvoxime, C,,H,,NOH, with sodium
amalgam and acetic acid, Goldschmidt obtained a base which he
called carvylamine, C,,H,,NH,. The existence of this compound
was subsequently questioned by Wallach,’ since he obtained dihy-
drocarvylamine, C,,H,,NH,, by reducing carvoxime with sodium
and alcohol ; Wallach also found dihydrocarvylamine, C,,H,,NH,,
to be identical with the base, prepared by Leuckart and Bach®
and by Lampe‘ on the treatment of carvone with ammonium
formate, which had previously been called ‘carvylamine,”

“Although in the German edition of this book, Dr. Heusler con-
siders Goldschmidt’s and Leuckart’s carvylamine as identical with
Wallach’s dihydrocarvylamine, it appears to the translator that
Goldschmidt” has sufficiently proved the existence of his carvy]-
amine, C,,H,,NH,, and has shown it to be quite different from
dihydrocarvylamine.

According to Goldschmidt,° when an alcoholic solution of dextro-
carvoxime is reduced with sodium amalgam, or zine dust, and
acetic acid, two optically active, isomeric bases are formed, which
are designated as a-d- and /-d-carvylamine, C,,H,,NH,. Levo-car-
voxime likewise gives rise to two bases a-l- and f-l-carvylamine,
whose derivatives have the same melting point, solubility, ete., as
those of the corresponding bases obtained from d-carvoxime, while
their optical rotation is the opposite. Two racemic compounds,
corresponding to the a- and /-carvylamines, have been separated
in the form of their benzoyl derivatives, so that altogether six
isomeric benzoyl carvylamines have been isolated.

1H. Goldschmidt, Ber., 19, 3232; 20, 486; 26, 2084.

2Wallach, Ann. Chem., 275, 120.

3Leuckart and Bach, Ber., 20, 105.

4Lampe, Inaug. Diss., Gottingen, 1889.

5Goldschmidt and Fischer, Ber., 30, 2069.

354

92701 <0 ie

8-D-CARVYL PHENYLCARBAMIDE. 355

The reduction of carvoxime is accomplished as follows. An
alcoholic solution of d-carvoxime is heated with zine dust and
acetic acid on the water-bath until no further precipitation of the
oxime takes place on pouring a little of the reaction-mixture into
water. The excess of zine is filtered off, the filtrate is diluted
with water, rendered acid with hydrochloric acid, and consider-
able regenerated carvone is extracted with ether. The acid
liquid is then rendered alkaline with sodium hydroxide, and
again extracted with ether ; after drying over potash and distilling
off the ether, the basic residue is rectified in vacuum, the product
boiling at 94° under 10 mm. pressure.

The liquid distillate has a basic odor, is sparingly soluble in
water, and consists of two bases, whose separation is accom-
plished by means of their nitrates ; the nitrate of $-d-carvylamine
is more difficultly soluble in water than its isomeride. The basic
mixture is neutralized with dilute nitric acid, and the resultant
salts are crystallized from a small quantity of warm water ; the
f-salt separates at first, and the filtrate may be used for the
preparation of the a-derivatives. .

The free bases may be obtained from their hydrochlorides or
nitrates by the action of alkalis ; they have a decided basic odor,
and rapidly absorb carbon dioxide from the air, forming solid
carbonates.

a-d-Carvylamine hydrochloride, C,,H,,NH,-HCl, crytallizes from
absolute alcohol in fine needles, melts with decomposition at 180°,
and is readily soluble in water.

a-d-Carvyl phenylearbamide, C,,H,,NH:-CONHC,H,, can not be
obtained entirely free of the f-derivative ; it is crystalline, and
melts at 187° to 191°.

Benzoyl-a-d-carvylamine, C,,H,,NH:COC,H,, is produced by
treating an aqueous solution of the a-d-nitrate with alkali and
benzoyl! chloride ; it usually contains some of the f-derivative as
an impurity, but after repeated crystallization from methy! alco-
hol, it is freed from most of the f-compound, It crystallizes
from methyl alcohol in long, white needles, and melts at 169° ;
it is levorotatory, [a], = — 91.9°.

a-d-Carvyl carbamide, C,,H,, NH-CONH,, is formed by warming
a solution of the hydrochloride with potassium cyanate ; it crystal-
lizes from hot water in white, miscroscopic needles, and melts at 187°.

The f-d-carvylamine may be readily obtained in a pure condi-
tion, since its nitrate is much more sparingly soluble in water
than the a-compound.

f-d-Carvyl phenylearbamide, C,,H,,NH ‘CONHC,H,, crystallizes
in small, white needles, and melts at 138°.

356 THE TERPENES.

Benzoyl-f-d-carvylamine, C,,H,,NH-COC,H,, is prepared from
the §-d-nitrate by treating with alkali and benzoyl chloride ; it
crystallizes from methyl alcohol in colorless needles, melts at
103°, and is more readily soluble in all solvents than the a-com-
pound. It is dextrorotatory, [a], = + 176.6°.

When l-carvoxime is reduced in alcoholic solution with zine
dust and acetic acid in a manner similar to that described above,
a mixture of two isomeric bases is obtained, which boils at 94°
to 95° under 10 mm. pressure. ‘These bases are also separated
by means of their nitrates, and the benzoyl derivatives are formed
like the corresponding d-compounds.

Benzoyl-a-l-carvylamine, C,,H,,NH-COC,H,, crystallizes from
methyl alcohol in long, white needles, melts at 169°, and is dex-
trorotatory, [a] >= + 92.6°.

Benzoyl-8-l-carvylamine, C,,H,,NH-COC,H,, crystallizes from
methyl alcohol, melts at 103°, and is levorotatory, [4]>=
— 175.4°.

Racemic benzoyl-a-carvylamine, (C,,H,.NH-°COC,H,),, is ob-
tained by crystallizing together equal weights of the a-d- and a-l-
derivatives from methyl alcohol ; it forms fine, white needles, and
melts at 141°. .

Racemic benzoyl-§-carvylamine, (C,,H,,NH-COC,H,),, is pro-
duced from the two f-compounds ; it crystallizes from methyl
alcohol in small prisms, and melts at 140°. It is more readily
soluble in all solvents than the preceding compound.

When the two isomeric racemic derivatives are rubbed together,
a mixture results, which melts at about 132°.

B. AMINES, C,,H,,NH,, CONTAINING ONE ETHYLENE
LINKAGE.

1. DIHYDROCARVYLAMINE, C,,H,,NH,.

By the treatment of carvone with ammonium formate, Leuckart
and Bach,' and Lampe? obtained a base which they called “ carvyl-
amine,” C,,H,,NH,. Wallach* subsequently showed that this
compound could be more conveniently prepared by reducing
carvoxime with sodium and alcohol, and further that its compo-_
sition was not expressed by the formula, C,,H,,NH,, but that it
had the constitution, C,,H,,NH,, dihydrocarvylamine. Wallach has

1Leuckart and Bach, Ber., 20, 105.
2Lampe, Inaug. Diss., Gottingen, 1889.
3Wallach, Ann. Chem., 275, 120; Ber., 24, 3984.

DIHYDROCARVYLAMINE HYDROCHLORIDE. 357

also regarded dihydrocarvylamine as chemically identical with
Goldschmidt’s carvylamine, C,,H,,NH,, but more recent publi-
cations * by Goldschmidt indicate that this view can no longer be
maintained.

For the preparation of dihydrocarvylamine according to
Leuckart’s method, ten grams of carvone are heated with
eleven grams of ammonium formate in sealed tubes at 180° to
200°, for five or six hours. On cooling, the tubes contain the
formyl derivative of the base as a dark, viscous mass, together
with some unchanged ammonium formate. The formyl com-_
pound is treated with water and extracted with ether ; the ethereal
solution is separated, the ether distilled off, and the resultant
product saponified with alcoholic potash. After the alcohol is re-
moved by distillation, the base is distilled with steam, and recti-
fied in vacuum. The yield is seventy to eighty per cent. of the
theoretical (Wallach ”).

In order to prepare the base by the reduction of carvoxime,’
twenty grams of the oxime are dissolved in one hundred and
seventy-five cc. of absolute alcohol and treated gradually with
twenty-five grams of sodium, the operation requiring one-half
hour ; the last particles of sodium are dissolved by the addition of
more alcohol. The product is distilled with steam, and the base
purified by distillation in vacuum.

Dihydrocarvylamine boils without appreciable decomposition at
218° to 220°; under 15 mm. pressure it boils at 93° to 95°. It
has a specific gravity of 0.889 and refractive power, np = 1.48294,
at 20°. It is optically active; on mixing the solutions of equal
quantities of the dextro- and levo-modifications, a racemic com-
pound is obtained, whose derivatives differ materially from those
_ of the active bases in melting point and solubility. It readily
absorbs carbonic anhydride from the air.

Dihydrocarvylamine hydrochloride, C,,H,,NH,-HCl, is precipi-
tated by passing hydrochloric acid gas into a dry ethereal solution
of the base; by the long-continued action of hydrogen chloride,
this salt is dissolved owing to the formation of a dihydrochloride,
which is soluble in ether. The monohydrochloride melts at about
200°, and decomposes readily into ammonium chloride and terpi-
nene; at a higher temperature this terpene is partially converted
into cymene by the elimination of hydrogen :—

CyoHy,NH,- HCl = NH,Cl +-CyoHis ;
CioHis — H, + CoH,

1Goldschmidt and Fischer, Ber., 30, 2069.
2Wallach, Ann. Chem., 275, 120; Ber., 24, 3984.

358 THE TERPENES.

Dihydrocarvylamine sulphate crystallizes in characteristic, lus-
trous leaflets, and is sparingly soluble. The owalate is also diffi-
cultly soluble.

When a solution of dihydrocarvylamine hydrochloride is
warmed with a solution of sodium nitrite, dihydrocarveol is
formed, together with dipentene (inactive limonene) ; the forma-
tion of this hydrocarbon is of interest since it indicates a trans-
formation of carvone into limonene.

Acetyl dihydrocarvylamine, C,,H,,NHCOCH,, is obtained by
warming the free base with acetic anhydride; it separates at first
as an oil which solidifies after some time, and may be crystallized
from hot water. It melts at 132°.

Benzoyl dihydrocarvylamine, C,,H,,NH-COC,H,, crystallizes
from methyl alcohol in needles, and melts at 181° to 182°.

Dihydrocarvyl phenylearbamide, C,,H,,NH:CO-NHC,H,, melts
at 191°.

Dihydrocarvyl phenylthiocarbamide, C,,H,,NH-CS-NHC,H,, is
prepared by mixing the methyl] alcoholic solutions of the molec-
ular proportions of the base and phenylcarbimide ; it forms small,
transparent prisms, which melt at 125° to 126°. When equal
quantities of the dextro- and levo-modifications are crystallized
together from methyl alcohol, the inactive thiocarbamide is ob-
tained ; it is more readily soluble, and does not form as well de-
fined crystals as the active modifications, and melts at 119°.

Dihydrocarvyldiamine,' C,,H,,(NH,),, is produced on the reduc-
tion of hydroxylaminocarvoxime with alcohol and sodium. It
is a colorless liquid, having a basic odor, boils at 258° to 260°
under atmospheric pressure, and at 122° to 123° (10 mm.) ; it
absorbs carbon dioxide from the atmosphere. Its hydrochloride is
hygroscopic, and the aurichloride crystallizes in long needles.
The oxalate melts at 135° to 140°, the dibenzoyl derivative at
275° to 276°, the diphenylcarbamide at 214° to 216°, and the
diphenylthiocarbamide at 179° to 180°.

On the dry distillation of dihydrocarvyldiamine, a hydro-
carbon, C,,H,,, isomeric with cymene, is formed ; it is an unsatu-
rated compound, and boils at 170° to 175°.

2. CARYLAMINE, C,,H,,NH,.

Carylamine is formed when one part of the oily caronoxime,
C,,H,,.NOH, is dissolved in twenty-one parts of alcohol and re-
duced with three parts of sodium (Baeyer’).

1Harries and Mayrhofer, Ber., 32, 1345.
2 Bayer, Ber., 27, 3486.

DIHYDROEUCARVYLAMINE,. 359

It has no characteristic odor. Its alcoholic solution is stable
towards potassium permanganate, hence Baeyer assumes that the
hexamethylene ring in carylamine contains either a para-linking
or a trimethylene ring.

Carylamine hydrochloride, C,,H,,NH,-HCl, is obtained by sat-
urating an ethereal solution of the base with hydrochloric acid
gas. On evaporation of the ether, the salt remains as a crystal-
line mass, which is readily soluble in water, alcohol and ether.
When its aqueous solution is evaporated, it is converted into the
isomeric yestrylamine hydrochloride. The aqueous solution of
carylamine hydrochloride gives no precipitate with platinic
chloride.

Benzoyl carylamine, C,,H,,NH-COC,H,, is prepared by Schot-
ten-Baumann’s method, and crystallizes from ethyl acetate in
large, fat prisms, which melt at 123°.

Caryl phenylthiocarbamide, C,,H,,NH:CS-NHC,H,, melts at
145° to 146°.

3. VESTRYLAMINE, C,,H,,NH,.

Carylamine is readily transformed into the isomeric, unsaturated
vestrylamine’ by saturating an alcoholic solution of carylamine
with hydrogen chloride, and heating the reaction-product on the
water-bath for one and one-half days; the hydrochloride of
vestrylamine is so obtained as a syrup, which gradually solidifies
to a crystalline mass.

Vestrylamine resembles carylamine in odor, but is immediately
attacked by permanganate. When treated with benzoyl chloride
and sodium hydroxide, it yields a resinous product from which
erystals of benzoyl carylamine may be separated, hence the con-
version of carylamine into vestrylamine is not quantitative.

When vestrylamine hydrochloride is subjected to dry distilla-
tion, it is decomposed into carvestrene and ammonium chloride :

C,)H,,NH,"HCl = C,,H,, + NH,Cl.

Carylamine hydrochloride likewise forms carvestrene by distil-
lation, but in this case the change is probably preceded by an
intramolecular transformation of carylamine hydrochloride into
vestrylamine hydrochloride.

. 4, DIHYDROEUCARVYLAMINE, C,,H,,NH,.
Dihydroeucarvylamine was obtained by Baeyer* in the reduc-
tion of eucarvoxime and of dihydroeucarvoxime hydriodide with

1Bayer, Ber., 27, 3486.
2Bayer, Ber., 27, 3487; Baeyer and Villiger, Ber., 31, 2067.

360 THE TERPENES.

sodium and alcohol. It has no characteristic odor, and its alco-
holic solution immediately reduces potassium permanganate. It
boils at 116° to 117° under a pressure of 40 mm.'

Dihydroeucarvylamine hydrochloride is crystalline and rather
sparingly soluble. The platinochloride is also crystalline and
difficultly soluble.

Benzoyl dihydroeucarvylamine, C,,H,,NH-COC,H,, obtained by
Schotten-Baumann’s method, is sparingly soluble in ether, and
crystallizes from ethyl acetate in long needles, melting at 155° to
156°. It is unstable towards permanganate.

Dihydroeucarvyl phenylcarbamide,' C,,H,,NH:CO:-NHC,H,,
melts at 142°, and the phenylthiocarbamide, C,,H,,NH:CS:NH-
C,H,, crystallizes from methyl alcohol in transparent plates, and
melts at 120° to 121°.

5. THUJYLAMINE (TANACETYLAMINE), C,,H,,NH.,

Tanacetylamine, C,,H,,NH,, is formed when ten parts of
tanacetoxime (m. p. 51. 15°) are reduced with twenty-five parts of
sodium and fifty parts of alcohol (Semmler’). The same base,
designated by Wallach as thujylamine, is obtained by reducing
thujonoxime (m. p. 54°) with alcohol and sodium (Wallach *).

According to Semmler, this compound boils at 80.5° under a
pressure of 14 mm., has the specific gravity 0. 8743 and a re-
fractive power, ny = 1.462, at 0°.

According to Wallach, it boils at 195°, has a specific gravity
of 0.8735 and refractive ‘index, Np = 1.4608, at 20°.

Thujylamine absorbs carbonic anhydride with great readiness,
forming the carbamate, which melts at 106° to 107°.

The nitrate is rather difficultly soluble in water, and melts at
167° to 168°.

The hydrochloride is precipitated from the ethereal solution of
the base as a gelatinous mass, which melts at 260° to 261°.
When dry distilled, it yields ammonium chloride and a terpene,
C,,H,,, which Wallach calls thujene and Semmler designates as
tanacetene. This hydrocarbon boils at 60° to 63° under a pres-
sure of 14 mm., has the specific gravity 0.8508 and refractive
power, np = 1.476, at 20° (Semmler). According to Tschugaeff,*
the dry distillation of thujylamine hydrochloride gives isothujene
and not thujene. It contains two ethylene linkages. :

1Wallach, Ann. Chem., 305, 223.
2Semmler, Ber., 25, 3345.
3Wallach, Ann. Chem., 286, 96.
4Tschugaeff, Ber., 34, 2276.

ISOMERIC THUJYLAMINE. 361

Thujyl phenylearbamide, C,,H,,NH-CO-NHC,H,, results by
the interaction of thujylamine and phenylcarbimide ; it crystal-
lizes in prisms, and melts at 120° (Wallach).

Dimethylthujylamine,' C,,H,,N(CH,),, is formed as a by-product
during the preparation of thujyl trimethyl ammonium iodide; it
boils at 213.5° to 214°, has a sp. gr. 0.8606 at 20°/4°, and
[a]p>=+141.76°. Its hydrochloride is very easily soluble in
water and alcohol, the platinochloride separates from hot alcohol
as an orange red, crystalline powder, and the nitrate crystallizes
readily and is only sparingly soluble in water and alcohol.

Thujyl trimethyl ammonium iodide,’ C,,H,,N(CH,),I, is formed

by the action of methyl iodide and potassium hydroxide on thujyl-
amine ; it crystallizes from a mixture of chloroform and methyl
alcohol in long, prismatic crystals, has the specific rotatory power
in chloroform solution, [¢]p = + 42.61°, and is only sparingly
soluble in cold water.
’ Thujyl trimethyl ammonium hydroxide,’ C,,H,,N(CH,),OH, is
obtained as a crystalline mass by treating the preceding com-
pound with moist silver oxide ; on dry distillation it is decomposed
with the formation of thujene, C,,H,, (b. p. 151° to 153°, sp.
gr. 0.8263 at 20°/4°, np =1.45022 at 20°, and [a],= —
8.23°).

It has already been mentioned that three isomeric thujonoximes
are known (see page 228). These oximes yield three different
amines on reduction. Thujonoxime, melting at 54°, gives the
above described thujylamine ; the isomeric thujonoxime, melting
at 90°, forms the isomeric thujylamine, boiling at 193°; and
isothujonoxime, melting at 119°, yields isothujylamine, boiling at

200° to 201°.

ISOMERIC THUJYLAMINE, C,,H,,NH,, PREPARED FROM THE
ISOMERIC THUJONOXIME, MELTING AT 90°.

When the isomeric thujonoxime, melting at 90°, is reduced
with sodium and alcohol, it yields a base, C,,H,,NH,, which boils
at 193°, and at 20° has the specific gravity 0.875 and refractive
index, np = 1.46256 (Wallach). It absorbs carbonic anhydride
slowly. Its nitrate crystallizes in needles, is readily soluble, and
melts at 124°; the hydrochloride separates in tablets, and melts at
216°; the phenylcarbamide forms transparent tablets, which melt
at 110°.

1Tschugaeff, Ber., 34, 2276.
2Wallach, Ann. Chem., 286, 96.

362 THE TERPENES.

Wallach' had previously obtained a thujylamine, boiling at
198° to 199°, by heating crude thujone with ammonium formate.
When the hydrochloride of this base is submitted to dry distilla-
tion, it is decomposed into ammonium chloride and _ thujene,
C,,H,,; this hydrocarbon boils at 172° to 175°, has the specific
gravity 0.840 and refractive index, np = 1.4761, at 20°.
Whether this amine is identical with the thujylamine prepared
from thujonoxime (m. p. 54°), or is to be regarded as a derivative
of carvotanacetone—the latter view is suggested by the high tem-
perature at which the compound is formed—can only be deter-
mined by a renewed investigation.

6. ISOTHUJYLAMINE, C,,H,,NH,,.

Isothujylamine is produced when isothujonoxime (m. p. 119° to
120°) is reduced with sodium and alcohol (Wallach ’).

It boils at 200° to 201°, has a specific gravity of 0.865 and a
refractive index, ny = 1.468, at 20°; it absorbs carbonic anhy-
dride very feebly.

The nitrate is sparingly soluble, and melts at 163°.

The hydrochloride is precipitated from a solution of the base in
dry ether by hydrochloric acid gas; it may be crystallized from a
mixture of chloroform and petroleum ether, and melts at 180° to
181°. When this salt is submitted to dry distillation, it is de-
composed into ammonium chloride and a terpene, which seems to
be identical with the above-mentioned thujene; the terpene boils
at 170° to 172°, its sp. gr. is 0.836 and refractive power, np =
1.47145, at 22°.

Isothujylearbamide, C,,H,,NH:CO-NH,, is prepared by the in-
teraction of isothujylamine hydrochloride and potassium isocya-
nate ; it melts at 158° to 159°. ;

Isothujyl phenylearbamide, C,,H,.NH-CO-NHC,H,, forms small
needles, which are readily soluble in alcohol, and melt at 178°.

Isothujyl phenylthiocarbamide, C,,H,,.NH:CS-NHC,H,, crystal-
lizes in needles, dissolves sparingly in methyl alcohol, and melts
at 152° to 158°.

7. PULEGYLAMINE, ©,,H,.NH,.

Pulegylamine is obtained by reducing the normal pulegonoxime,
C,,H,,NOH, in an alcoholic solution with sodium. It is a erys-
talline compound, and is purified by means of its readily soluble
oxalate; it melts at about 50°, boils at 205° to 210°, and com-
bines with great readiness with carbonic anhydride.

1Wallach, Ann. Chem., 272, 109.
2Wallach, Ann. Chem., 286, 97.

ner pet =,

an i eccrine

METHYL PULEGONAMINE. 363

Pulegylamine hydrochloride is insoluble in ether, and yields a
carbamide, melting at 104° to 105°, when treated with potassium
isocyanate.

Pulegyl phenylcarbamide, obtained from the free amine and car-
banile, melts at 154° to 155° (Wallach’).

Beckmann and Pleissner” obtained a base, C,,H,,ON, which
they termed pulegonamine, by the action of hydriodic acid on the
‘hydrated pulegonoxime,” C,,H,,NO,. According to these
chemists, this amine is prepared when ten parts of “hydrated
pulegonoxime” are treated with twenty parts of strong hydriodic
acid and a little red phosphorus; the mixture is warmed until
the reaction commences, and is then allowed to stand for some
time. Two layers are formed, a light colored aqueous solution
and a dark oil. The product is diluted with water, and decolor-
ized with thiosulphate, the oil being dissolved. The sulphur and
phosphorus are filtered off, the solution is shaken with ether, and
then rendered alkaline; the resulting pulegonamine is extracted
with ether. On evaporation of the ether, the base remains as a
yellowish oil, having a basic odor and bitter taste ; it decomposes
when distilled.

This amine does not reduce Fehling’s solution, and does not
give the isonitrile reaction. If hydrochloric acid gas be passed
through its ethereal solution an oil is precipitated, which solidifies
after repeated washing with ether, and crystallizes from absolute
alcohol in long needles, melting at 117°. This salt is not
homogeneous, but contains more chlorine than the formula,
C,,H,, NO-HCI, demands.

Pulegonamine phenylthiocarbamide,
NC,)H,,0

é
NHC,H;

is obtained by the action of phenylthiocarbimide on a solution of
pulegonamine in benzene ; it crystallizes from benzene in white
plates, and melts at 198°.

Benzoyl pulegonamine, C,,H,,ON-COC,H,, is formed by treating
an ethereal solution of the base with benzoyl chloride ; it sepa-
rates from dilute alcohol in lustrous, feathery crystals, which melt
at 100.5° to 101°. | a

Methyl pulegonamine, C,,H,,ON-CH,, is produced by boiling
pulegonamine with methy] iodide and decomposing the reaction-
product with potash ; it is a light yellow oil, having a penetrating,

1Wallach, Ann. Chem., 289, 347.

2Beckmann and Pleissner, Ann. Chem., 262, 13.

364 THE TERPENES.

fish-like smell. . Its platinochloride, (C,,H,.NOCI),PtCl,, crystal-
lizes in well defined needles.

When pulegonamine is boiled with potash, it is converted into
pulegone and ammonia; under the same conditions, methyl pule-
gonamine yields pulegone and methylamine; in both cases, how-
ever, the resultant pulegone apparently contains a nitrogenous
substance as an impurity.

The constitution of pulegonamine, therefore, differs entirely
from that of the other terpene bases. Beckmann and Pleissner
assume that the isonitroso-group (NOH) in pulegonoxime is
changed into the NH-group by treatment with hydriodic acid.

C. AMINES, C,,H,,NH,, WITHOUT AN ETHYLENE LINKAGE.

1. CARVOMENTHYLAMINE (TETRAHYDROCARVYLAMINE),
C,,H,,.NH,,.

(Amido-2-hexahydrocymene.)

When the oxime of tetrahydrocarvone (carvomenthone),
C,,H,, NOH, melting at 105°, is reduced with sodium and alcohol
by the same method which serves for the preparation of menthyl-
amine from menthonoxime (see page 368), an amine isomeric with
menthylamine is obtained. Wallach’ regards this compound as
having the constitution of an amido-2-hexahydrocymene; it may
be designated as carvomenthylamine or tetrahydrocarvylamine :

H, .
‘H
be CHNH,
H, H,
‘H
H
H,C CH;.

The optically active modifications of this base are obtained,
together with optically active tetrahydrocarveol and tetrahydro-
carvone, when phellandrene nitrosite is reduced with sodium and
alcohol (Wallach and Herbig ’).

1Wallach, Ann. Chem., 277, 137.
2Wallach and Herbig, Ann. Chem., 287, 371.

z
a
i

- :

MENTHYLAMINE, 365

Carvomenthylamine is a liquid, and boils at 211° to 212°,
considerably higher than menthylamine ; the other properties of
both amines are very similar. It unites with carbon dioxide with
great readiness, forming a solid salt.

Carvomenthylamine hydrochloride, C,,H,,NH,-HCl, is insoluble
in ether and sparingly soluble in cold water ; its optically active
modifications melt at 199° to 204°, while the inactive derivative
melts at 221° to 222°. It resembles menthylamine hydro-
chloride in that it may be distilled at a high temperature with
only slight decomposition. The platinochloride is very easily
soluble in alcohol, more sparingly in water.

Formyl carvomenthylamine, C,,H,,NHCOH, is obtained as an
oil by the distillation of the formate. It solidifies gradually, but
on recrystallization it separates at first from all solvents as an oil.
The inactive modification melts at 61° to 62°.

Acetyl carvomenthylamine, C,,H,,NHCOCH,, is formed by
warming the base with acetic anhydride ; it crystallizes from dilute
alcohol in small needles. The active derivatives melt at 158° to
159°, whilst the inactive modification melts at 124° to 125°.

Carvomenthyl phenylthiocarbamide, C,,H,,NH-CS:‘NHC,H,, is
prepared by the action of phenylthiocarbimide on carvomenthyl-
amine; it forms a viscous mass, which solidifies slowly. The
pure, inactive derivative crystallizes from methyl alcohol in
small, white needles, which melt at 117°.

Carvomenthyl carbamide, C,,H,,NH-CO-NH,, is best adapted
for the characterization of carvomenthylamine. It is precipitated
by heating carvomenthylamine hydrochloride 'with a solution of
potassium isocyanate ; it is insoluble in water, and is not readily
soluble in hot alcohol. The racemic compound crystallizes from
methyl alcohol in brilliant leaflets or needles, and melts at 193° to
194° ; the active modifications melt at 201° to 208°.

Carvomenthyl phenylearbamide,' C,,H,,NH-CO-NHC,H,.—The
inactive modification melts at 145° to 150°, and the active de-
rivatives at 185° to 186°.

Optically active carvomenthol’ is formed when the salts of op-
tically active carvomenthylamine are treated with a solution of
sodium nitrite.

2, MENTHYLAMINE, C,,H,,NH,.

Menthylamine was first prepared by Moriya * by the reduction
of a nitro-compound, obtained by the action of strong nitric acid

1Wallach and Herbig, Ann. Chem., 287, 371.
2Moriya, Journ. Chem. Soc., 1881, 77.

366 THE TERPENES.

on menthol, with tin and sulphurie acid; the properties of this
amine were very incompletely described. Andres and Andreef?
subsequently showed that a base having a strong levorotatory
power was formed by reducing levo-menthonoxime with sodium
and alcohol. Wallach and Kuthe’ then obtained the same re-
sults, although Wallach* had previously shown that a base,
C,,H,,NH,, could be produced by the treatment of menthone with
ammonium formate.

According to Wallach and Kuthe, levo-menthylamine prepared
from levo-menthonoxime is strongly levorotatory, and is chemically
different from the feebly dextrorotatory menthylamine, which may
be obtained, together with some of the levorotatory isomeride, by
the action of ammonium formate on levo-menthone. Wallach
explains the simultaneous formation of both bases by the follow-
ing considerations.

Levorotatory menthone contains two asymmetric carbon atoms.
When menthone is converted into menthylamine, the carbonyl
group is changed into the group, CH:NH,, and a third asym-
metric carbon atom is introduced, as shown by the formulas in
which the asymmetric atoms are represented by heavy type:

Gis H,
H H
Le H, Be
H,C ial H, HNH.
H H
C,H, 3H,
Menthone. Menthylamine.

If it be assumed that the two asymmetric carbon atoms in
levo-menthone and levo-menthonoxime influence the levorotatory
power of these compounds in the same direction although to an
unequal extent, the two substances can be represented :

(—, —)CjoHg0 and (—, —)CioHig:NOH.

By the transformation into menthylamine, the third asymmetric
carbon atom may increase this levorotation and a levorotatory
menthylamine may be formed which would be expressed by the
symbol :

(—, —, —)CioHigNH, ;

or, the third asymmetric atom may act in the opposite direction

1Andres and Andreef, Ber., 25, 618; 24, 560, Ref.
2Wallach and Kuthe, Ann. Chem., 276, 296; compare Ber., 25, 3313.
3Wallach, Ber., 24, 3992.

MENTHYLAMINE. 367

to those already present, and a compound be obtained which has
a weaker power of rotation, or, as in the case under consideration,
it may rotate the plane of polarized light slightly to the right ;
the symbol of the resultant dextrorotatory menthylamine would be :

=, aes +) CioHigN H,.

This hypothesis, proposed by Wallach, explains the facts that
levo- and dextro-menthylamines are not related to each other in
the same manner that an object is to its reflection, and, moreover,
that they are chemically different.

It would be expected that compounds having rotatory powers
exactly opposite to those of the above-mentioned menthylamines
would result if dextro-menthone were employed instead of levo-
menthone. Experiments in this direction were made by Wallach
and Kuthe, and by Negoworoff,’ but the preparation of such
bases in a condition of purity has not succeeded.

The behavior of the two menthylamines towards nitrous acid is
quite characteristic. Under the influence of this reagent, l-men-
thylamine is readily converted into the ordinary, solid 1-menthol,
while under the same conditions, d-menthylamine yields large
quantities of menthene. Consequently d-menthol, corresponding
to d-menthylamine, possesses a much greater tendency to lose the
elements of water than the common |-menthol ; therefore, the hy-
droxyl-group in d-menthol probably stands in a closer structural
relation to the tertiary hydrogen atom attached to the adjoining
carbon atom than is the case in the molecule of 1-menthol.
From this Wallach concludes that the isomerism in the menthyl-
amine series is to be explained as a cis- and trans-isomerism ;
l-menthylamine and ]-menthol are to be regarded as trans-com-
pounds, and the dextro-isomers as cis-derivatives. The following
formulas will illustrate this.

ss CH,
H ~
H, ‘vn HAG ‘it
H, y ae ‘NH, H,G CH-NH,
( ys
0H, H,C, ‘x
Trans-(1)-Menthylamine. Cis-(d)-Menthylamine.

If, in the above formulas, the NH, group be replaced by the
(OH) group, the corresponding menthols result, and" it will be

'Negoworoff, Ber., 25, 162¢e.; compare Ber., 25, 620.

368 THE TERPENES.

observed that menthene can be formed more readily by the elimi-
nation of water from cis-menthol than from trans-menthol.

(a) 1-(TRANS-) MENTHYLA MINE.

]-Menthylamine was first obtained pure by Andres and Andreef.
It may be prepared by the following method.

Ten grams of pure levo-menthonoxime are dissolved in seventy-
five grams of absolute alcohol, and fifteen grams of sodium are
added in small portions at a time to the boiling solution. The
crystallization of sodium alcoholate is prevented by the occasional
addition of absolute alcohol, the total amount added being about
sixty cc. When the sodium is dissolved, the product is distilled
with steam, and the receiving vessel is changed as soon as the
distillate appears cloudy. The yield is nearly quantitative.
After drying over potash, the amine boils at 209° to 210°; it
has a disagreeable, strongly basic odor, and rapidly absorbs car-
bonic anhydride from the air. It has the sp. gr. 0.86 and re-
fractive index, np = 1.46058, at 20°; [a], = — 38.07°.

I-Menthylamine hydrochloride, C,,H,,NH, HCl, is precipitated
from ethereal solutions of the base as a white powder; it dis-
solves readily in alcohol and warm water. It does not melt at
280°, and at higher temperatures it may be distilled without de-
composition.

1-Menthylamine hydrobromide, C,,H,,NH,*HBr, is more spar-
ingly soluble in water than the hydrochloride, and crystallizes
from water in needles. The Aydriodide is more difficultly soluble
than the hydrobromide.

1-Menthylamine nitrite, C,,H,,.NH, HNO,, is prepared from
molecular proportions of the hydrochloride of the base and sodium
nitrite ; on heating, it is converted into menthol,

C,,H,,NH,: HNO, = C,,H,,OH + H,O + N,.

1-Formyl menthylamine, C,,H,,NH-COH, is best prepared by the
distillation of the molecular quantities of the base and anhydrous

formic acid. It is washed with water, and separates from methyl —

alcohol in splendid crystals, which melt at 102° to 103°.

1-Acetyl menthylamine, C,,H,,NH-COCH,, is obtained by the
addition of the theoretical quantity of acetic anhydride to a sclu-
tion of the base in three times its volume of ethyl] acetate ; a vigor-
ous reaction takes place, and the acetyl derivative crystallizes from
the cold solution. It is readily soluble in alcohol, ether and
chloroform, but almost insoluble in petroleum ether; it crystal-
lizes from ethyl acetate, and melts at 145°.

- \
——s)

ae

ae ee aa eae

er

L-MENTHYL TRIMETHYL AMMONIUM IODIDE. 369

1-Propionyl menthylamine, C,,H,,NH-COC,H,, is more readily
soluble than the formyl and acetyl derivatives ; it crystallizes from
ethyl acetate or acetone, and melts at 89°.

1-Butyryl menthylamine, C,,H,,NH-COC,H,, tends to separate
from most solvents as an oil, but by recrystallization from acetone
it is obtained in prisms, which melt at 80°.

1-Menthyl carbamide, C,,H,,-NH-CONH,, is obtained as an oil by
the action of potassium isocyanate on ]-methylamine hydrochloride ;
it solidifies after standing some time, and melts at 134° to 136°.

1-Menthyl phenylcarbamide, C,,H,,NH-CONHC,H,, results by
the action of carbanile on the free base ; it crystallizes from alcohol,
and melts at 140° to 141°.

1-Menthyl phenylthiocarbamide, C,,H,,.NH-CS-NHC,H,, results
when an ethereal solution of menthylamine is treated with the
molecular amount of phenylthiocarbimide ; the reaction is ener-
getic. It separates from ethyl acetate in lustrous crystals, and
melts at 135°.

1-Benzylidene menthylamine, C,,H,, N=CHC,H,, is obtained by
the action of benzaldehyde on menthylamine in a methy] alcoholic
solution ; it is crystallized from methyl alcohol, and melts at 69°
to 70°.

1-Ortho-oxybenzylidene menthylamine, C,,H,,N = CH:C,H,OH,
is produced in an analogous manner to the preceding compound ;
it separates at first as an oil, which solidifies after washing with
soda and cooling in a freezing mixture. It crystallizes in yellow
needles, and melts at 56° to 57°.

The nitroso-derivatives of the monoalkyl menthylamines are
formed by treating one molecular proportion of menthylamine
with one molecule of an alkyl iodide, liberating the free base from
the resulting mixture, dissolving in hydrochloric acid, and treating
with sodium nitrite. The resultant nitroso-derivatives of the
secondary amines are distilled with steam, dried and rectified in

. vacuum.

1-Menthyl methylnitrosamine, C,,H,,N(NO): CH,, is a yellow oil,
boiling at 145° to 146° under 18 to 20 mm. pressure.

1-Menthy] ethylnitrosamine, C,,H,,N(NO)-C,H,, crystallizes from
dilute methyl aleohol in colorless needles, melts at 52° to 53°,
and boils at 155° to 156° (22 mm.). |

1-Menthyl propylnitrosamine, C,,H,,N(NO)C,H,, boils at 159°
to 161° (20 mm.). ve

1-Menthyl isobutylnitrosamine, C,,H,,N(NO)C,H,, crystallizes in
white needles, melts at 52° to 53°, and boils at 160° to 161°.

1-Menthyl trimethyl ammonium iodide,-C,,H,,N(CH,),I, crystal-
lizes from water in large, colorless crystals, and melts at 190°.

, a

370 THE TERPENES.

Its alcoholic solution absorbs one molecule of iodine, forming a
triiodide, C,,H,,N(CH,),I,, melting at 117° to 118°.

1-Menthyl trimethyl ammonium hydroxide, C,,H,,N(CH,),OH, is
produced by digesting the preceding compound with moist silver
oxide ; it is a colorless, crystalline, hygroscopic mass. On distil-
lation under atmospheric pressure, it is decomposed into water,
trimethylamine, and menthene, C,,H,,; the latter boils at 170° to
171°, has the specific rotatory power, [a], = + 89.307°, and
does not yield a nitrosochloride.

(b) d-(CIS-)MENTHYLAMINE.

When five grams of levorotatory menthone are heated with
six grams of ammonium formate in sealed tubes at 190° to 200°
for several hours, a mixture of the formyl derivatives of l- and
d-menthylamines is obtained. d-Formyl menthylamine is char-
acterized by its great power of crystallization, and is more spar-
ingly soluble than the isomeric |-compound. Therefore, the con-
tents of the tubes are washed out with ether and water, the
ethereal solution is separated and allowed to evaporate slowly ;
most of the d-formy] derivative separates in well defined crystals.
On further evaporation of the mother-liquors, an oil is obtained,
which is distilled in vacuum ; the fraction boiling at 180° to 183°
at a pressure of 18 mm. to 20 mm. yields, on cooling, additional
quantities of the d-formyl derivative, which may be completely
freed from the mother-liquor by washing with petroleum ether.
d-Formyl menthylamine is recrystallized from -acetic ether. The
yield amounts to fifty or sixty per cent. of the theoretical.

Together with d-formyl menthylamine, of which considerable
quantities remain in the oily mother-liquors, l-formyl menthyl-
amine and menthol are formed by the action of ammonium for-
mate on levo-menthone ; the presence of the l-base may be proved
by its transformation into |-menthylamine hydrochloride, which is
insoluble in ether.

Larger quantities of the d-base may be conveniently prepared
by the following method.’ In a 250 ce. round-bottom flask hay-
ing a glass tube, one meter in length, sealed to it, ten grams of
menthone and twelve grams of dry ammonium formate are heated
over a direct flame for two days. The reaction-product separates
into two layers, the lower, aqueous layer being light colored, the
upper, a thick, brown oil. The latter is separated from the
aqueous liquid, and is freed from unaltered menthone by steam
distillation; the residual oil is then distilled under reduced

1Wallach and Werner, Ann. Chem., 300, 283.
i

7

D-BUTYRYL MENTHYLAMINE. 371

pressure, the largest portion of which boils at 165° to 175°
(20 mm.), and forms a colorless syrup ; on cooling, or after stand-
ing for several days, the oil begins to solidify. The erystalliza-
tion of the oil may be accelerated by rubbing up the syrupy mass
with ether ; the crystals are filtered, recrystallized from ether, and
consist of d-formyl menthylamine, melting at 117° to 118°. The
I-derivative is more soluble in ether, and only crystallizes after
allowing the ethereal filtrate to stand during a considerable time.

The formyl] derivative of d-menthylamine, obtained by either
of the above-mentioned methods, is saponified by heating with
alcoholic potash, or better by boiling for two hours with concen-
trated hydrochloric acid; the resulting acid solution is concen-
trated until crystallization commences, and the free base is sepa-
rated by means of alkali.

d-Menthylamine boils at 207° to 208°, has the specific gravity
0.857, the refractive index, np = 1.45940, and the specific rota-
tory power, [a] ,= + 14.71°; in other properties the two men-
thylamines are similar, but their derivatives differ very decidedly
in melting point, solubility, etc.

d-Menthylamine hydrochloride, C,,H,,NH,-HCl, can not be pre-
cipitated from the ethereal solution of the base; one hundred
parts of ether at 15° dissolve twenty-two grams of this salt.
It crystallizes from ether in splendid, transparent prisms, which,
however, soon become opaque, and decompose. It is rather easily
soluble in water and crystallizes from it in anhydrous plates,
melting at 189°.

d-Menthylamine hydrobromide, C,,H,,NH,°HBr, is sparingly sol-
uble in ether, and crystallizes from water in fine, small needles,
which melt at 225°.

d-Menthylamine hydriodide, C,,H,,NH,°H1, is slightly soluble in
water. and ether, and melts at 270° with decomposition.

d-Formyl menthylamine, C,,H,, NH-COH, is prepared according
to the above-described method ; it is also formed by heating the
free base with formic acid at 200°. It separates from methy] al-
cohol in very beautiful crystals, which melt at 117.5° ; it is spar-
ingly soluble in ether and ethyl acetate, more difficultly in ligroine.

d-Acetyl menthylamine, C,,H,,NH-COCH,, is obtained in the
same manner as the corresponding |-derivative; it crystallizes
from ethyl acetate in lustrous prisms, melts at 168° to 169°, and
is readily soluble in ether and methyl alcohol.

d-Propionyl menthylamine, C,,H,,NH-COC,H,, melts at 151°.

d-Butyryl menthylamine, C,,H,,NH-COC,H,, melts at 105° to
106°, dissolves readily in methy] alcohol, sparingly in ethyl ace-
tate, and very difficultly in ether and ligroine.

372 THE TERPENES.

d-Menthyl carbamide, C,,H,,; NH-CONH,, crystallizes from
dilute alcohol, and melts 155° to 156°.

d-Menthyl phenylearbamide, C,,H,,NH-CONHC,H,, crystallizes
from alcohol in fine needles, and melts at 177° to 178°.

d-Menthyl phenylthiocarbamide, C,,H,,NH-CS NHC,H,, is pre-
pared like the |-derivative ; it separates from methyl alcohol in
small crystals, having a diamond-like luster, and melts at 178°
to 179°.

d-Menthy]l allylthiocarbamide, C,,H,,NH:CS:NHC,H,, is formed
by the action of allylthiocarbimide on an ethereal solution of
d-menthylamine ; it is very soluble in methyl alcohol, and crys-
tallizes from a mixture of ether and ligroine in brilliant prisms,
which melt at 110°. The analogous compound of the levo-series
is an oil.

d-Menthy! trimethyl ammonium iodide, C,,H,,N(CH,),I, erys-
tallizes from hot water, and melts at 160° to 161°.

d-Menthyl trimethyl ammonium hydroxide, C,,H,,N(CH,),OH,
is prepared from the iodide by means of moist silver oxide. On
heating, it is resolved into water, trimethylamine, and menthene ;
the latter boils at 167°, and readily yields a nitrosochloride.

d-Benzylidene menthylamine, C,,H,,N = CHC,H,, is obtained by
the condensation of the base with benzaldehyde in an ethereal so-
lution. It crystallizes in lustrous needles, which melt at 42° to
43°. ;

d-Ortho-oxybenzylidene menthylamine, C,,H,,N = CHC,H,OH,
crystallizes from methyl alcohol in yellow needles, melting at
96° to 97°.

When an aqueous solution of d-menthylamine hydrochloride is
boiled with sodium nitrite, and the reaction-product is distilled
with steam, a liquid results, which boils at 55° to 95° under a
pressure of 20 mm.; on repeated fractionation, this oil is sepa-
rated chiefly into low boiling portions from which menthene is
obtained. It boils at 164° to 165°, has the sp. gr. 0.8175, and

a|y= + 55.44°. It forms a nitrosochloride, from which men-
thene nitrolbenzylamine (m. p. 107° to 108°) is obtained.

The higher boiling fractions contain a small quantity of menthol,
and possibly a little menthone; on oxidation with chromic acid,
a product is formed which gives a semicarbazone (m. p. 184°),
probably identical with l-menthone semicarbazone.

]-Menthylamine is not converted into d-menthylamine at high
temperatures, and the derivatives of the levo-base ean not be
transformed into those of the dextrorotatory amine.

An investigation regarding the optical behavior of ]- and
d-menthylamines, and of their salts and derivatives has been

- —

i

TERTIARY CARVOMENTHYLAMINE. 373

earried out by Wallach and Binz.’ The following table presents
the most important values obtained for the specific and molecular
rotatory powers of these compounds.

Solvent, [2] p, [1] p.
l-Menthylamine..............-ssscssesesenees no —38.07° —58.90°
5 hydrochloride.. ........ Water —35.66 —68.15
oe hydrobromide........... Ke — 29.32 —69.04
“ hydriodide .............. “s —24.72 —69.77
d-Menthylamine...............sss0eseeeeeeees — +14.71 +22.76
& hydrochloride........... Water +17.24 +32.94
“is hydrobromide wares tans es +13.83 +32.56
«“ hydriodide.............+. “ +11.79 +33. 28
si hydrochloride ........... Ether + 8.34 +15.94
“s hydrobromide........... - + 5.26 +12.38
an pe menthylamine hapad wabewan hbase sg —152.27 ,
PRCOEY TL ice 0 “saspechaad veces onss> —8l. —160.84
| SOR 8 |” Wiasepsdequunavstane —76.53 —161.15
l-Butyryl Rie |, | educeicndeate tener Re —72.10 —161.90
d-Pormyl 6 svntnsesene wae +5403 | 498.68
-Acety Pic tewe stud vetecetes ; ;
GL TORVORN RE = iatasn cei cckiwandnve +45.14 +95.05
d-Butyryl er ire ve veten voxk ‘ +40.59 +91.14

; Wallach and Binz have also obtained values for the rotatory
powers of these compounds in other solvents.

3. TERTIARY CARVOMENTHYLAMINE, C,,H,,NH,.

According to Baeyer,’ tertiary carvomenthylamine results,
together with regenerated carvomenthene, when tertiary carvomen-
_thyl iodide or bromide, formed by the addition of hydriodic acid
or hydrobromic acid to carvomenthene, is treated in an ethereal
solution with silver cyanide, and the resultant oil is saponified
with potash.

Hg
NH,
H, H,
H, H,
‘H
3H,

Tertiary carvomenthylamine.

1Wallach and Binz, Ann. Chem., 276, 317; compare Zeitschr. fiir physik.
Chem., 12, 723.
2Baeyer, Ber., 26, 2271.

374 THE TERPENES.

Tertiary carvomenthylamine hydrochloride is soluble in ether, and
on evaporation of the solvent it remains as a syrup, which solidifies
gradually.

The platinochloride is a solid ; the gold double salt is precipitated
as an oil, which soon solidifies, forming large, lustrous plates.

The benzoyl derivative crystallizes in large needles, melting at
110° ; the phenylthiocarbamide forms prisms, which melt at 128°.

4, TERTIARY MENTHYLAMINE, C,,H,,NH,,

Tertiary menthyl iodide or bromide, obtained by direct addition
of hydriodic acid or hydrobromic acid to menthene, forms tertiary
menthylamine when treated according to the method given under
the preceding compound ; the yield is about ten per cent. of the
theoretical. According to Baeyer,' this amine has the consti-
tution :

JH

H.C ‘CH,
HC CH,
NH,
C,H,.

Tertiary menthylamine hydrochloride, C,,H,,NH,"HCl, is soluble
in, and crystallizes from, ether; it melts at about 205°. The
platinochloride crystallizes from alcohol in lustrous leaflets, and
melts at 235°. The gold double salt forms an oil, which partially
solidifies in needles.

The phenylthiocarbamide crystallizes in leaflets, and melts at
118° to 119°. The benzoyl derivative separates in needles, which
melt at 154.5°.

AMIDO-DERIVATIVES OF PHELLANDRENE.
1, AMIDOPHELLANDRENE, ©,,H,,NH,,
The so-called nitrophellandrene, C,,H,,NO,, obtained by Pesci

by the action of ammonia on phellandrene nitrosite, may be con-
verted into amidophellandrene by the following method (Pesci *).

Twenty grams of nitrophellandrene are dissolved in a mix-
ture of sixty grams of glacial acetic acid and an equal volume
of alcohol; the solution is gradually treated with thirty grams

1Baeyer, Ber., 26, 2270 and 2562.
2Pesci, Gazz. Chim., 16, I., 228; Jahresb. Chem., 1884, 547.

a
’

DIAMIDOPHELLANDRENE. 375

of zine dust, and is heated on the water-bath at 70° after the
first violent reaction has taken place. The reaction-product is
diluted with water, neutralized with sodium hydroxide, and
shaken with ether. The base is removed from the ethereal solu-
tion by dilute hydrochloric acid, the acid solution is rendered al-
kaline, and the amidophellandrene is again extracted with ether
and purified by distillation with steam.

It is an oily liquid, having a penetrating odor like that of
conine ; it is moderately soluble in water, and absorbs carbonic
anhydride with great readiness.

Amidophellandrene sulphate, (C,,H,,NH,),-H,SO,, is rather spar-
ingly soluble in cold water. The hydrochloride is crystalline,
and easily soluble in alcohol and water. The platinochloride,
(C,,H,,NH,-HCl),PtCl,, forms yellow, hexagonal, microscopic
plates which are insoluble in water, but readily soluble in warm
alcohol. The mercuric double salt is crystalline, and sparingly
soluble.

It has been mentioned that phellandrene nitrosite, and the com-
pound, C,,H,,NO,, obtained by Wallach in the treatment of
phellandrene nitrosite with sodium alcoholate, are both converted
into optically active tetrahydrocarvylamine on reduction with
sodium and alcohol.

2. DIAMIDOPHELLANDRENE, C,,H,,(NH,),.

A diamine, C,,H,,(NH,),, was obtained by Pesci’ by the
reduction of phellandrene nitrosite.

For the preparation of this base, phellandrene nitrosite is
mixed with alcohol to form a thick paste, and is reduced by the

. addition of about ten per cent. of glacial acetic acid and zinc dust ;

the zine dust is added to the well cooled mixture in small por-
tions at a time until the reaction is complete. The reaction-
product is warmed at 40° to 50° for some time, then for one hour
at 90,° and is diluted with water. The zinc is precipitated with
hydrogen sulphide, filtered off, and the filtrate acidified with hydro-
chloric acid ; this solution is evaporated to a small volume, made
alkaline, and distilled with steam. The distillate is acidified with
hydrochloric acid and evaporated, the residue is treated with
potash, and the free base extracted with ether; after drying the
ethereal solution with solid potassium hydroxide, the ether is dis-
tilled off, and the amine is rectified.

Phellandrene diamine is a colorless, odorless liquid, having a
strong refractive power; it boils at 209° to 214° with slight de-

1Pesei, Gazz. Chim., 16, I., 229; Jahresb. Chem., 1885, 698.

composition. It is readily soluble in water and alcohol, m
sparingly in ether, chloroform and ligroine.

The a: is crystalline but hygroscopic ; it yields
platinochloride, C “H, (NH), -2HCI-PtCl,, which erystallizes ,
monoclinic prisms.

The sulphate, acetate, nitrate and tartrate of phellandrene dia
_ mine are hygroscopic.

OLEFINIC MEMBERS OF THE TERPENE SERIES.

A. HYDROCARBONS.

1. MYRCENE, C,,H,,.

Bay oil contains eugenol, methyl eugenol, chavicol, methyl
chavicol, geranial and two hydrocarbons, C,,H,,. Mittmann!
regarded these hydrocarbons as pinene and another terpene, prob-
ably dipentene ; Power and Kleber,’ however, proved that bay
oil contains levorotatory phellandrene and a hydrocarbon, C,,H,,,
which they called myrcene. This hydrocarbon has an open
chain and may be designated as an aliphatic terpene. Myrcene
is also found in the oil of sassafras leaves.*

According to Power and Kleber, myrcene is obtained from the
oil of bay by the following process. The oil is first shaken with
a five per cent. solution of sodium hydroxide to remove phenols,
and is then subjected to a fractional distillation in vacuum.
(Myrcene is very readily polymerized by distillation under ordi-
nary pressure.) About eighty per cent. of the oil from which the
phenols are removed distills between 67° and 80° under a pressure
of 20 mm. By repeated fractionation of this distillate in vacuo,
a colorless liquid results, which boils at 67° to 68° under 20
mm. pressure; this liquid has a characteristic odor unlike that of
the other terpenes. It has a specific gravity 0.8023 at 15°, con-
siderably lower than that of the common terpenes. ‘The coeffi-
cient of refraction, np = 1.4673, is also remarkably small, and
indicates that myrcene contains three double linkages.

When a mixture of one part of myrcene, three parts of glacial
acetic acid, and a small amount of dilute sulphuric acid is digested
for three hours at 40°, according to Bertram’s * method, the product
contains an oil, having a lavender-like odor ; if this oil be saponi-
fied with potash, and subsequently fractionated in a vacuum, a
product is obtained which consists of unchanged myrcene, dipen-
tene and linalool, C,,H,,OH. The presence of linalool is proved

IMittmann, Arch. Pharm., 1889, 529.

2Pharm. Rund., New York, 1895, No. 13; Semi-Annual Report, Schim-
mel & Co., April, 1895, 11.

3Power and Kleber, Pharm. Review, 1896.

‘German Patent, No. 80,711.

377

378 THE TERPENES.

by its conversion into the aldehyde geranial (citral), C,,H,,O, by
careful oxidation, and by the characterization of the latter com-
pound in the formation of the crystalline geranial-f-naphthocin-
chonic acid (see geranial, page 399). Since myrcene may be con-
verted into linalool, C,,H,,OH, it bears the same relation to this
alcohol as does camphene to isoborneol, and pinene or dipentene
to terpineol (Power and Kleber).

According to Barbier,’ however, the alcohol, C,,H,,OH, ob-
tained by Power and Kleber on hydrating myrcene as above men-
tioned, is not identical with linalool (Barbier’s “licareol’’), but is
isomeric with it; Barbier designates it by the name myrcenol,
C,,H,,OH. He describes it as a colorless, oily liquid boiling at
99° to 101° (10 mm.), and slowly undergoing polymerization ; it
has the sp. gr. 0.9012 and the refractive index, n, = 1.47787, at
14.5°. Myrcenyl acetate, C,,H,,OOCCH,, is a colorless liquid
boiling at 111° to 112° (10 mm.). When myrcenol is oxidized
with a sulphuric acid solution of chromic acid, it yields acetone,
laevulinic acid, and an aldehyde, C,,H,,O (not geranial), boiling
at 110° (10 mm.). ‘This aldehyde forms an oxime, C,,H,,,NOH,
which boils at 148° to 150° (10 mm.), and is converted into the
aldehyde by boiling with a solution of oxalic acid. The semi-
carbazone is a crystalline powder, melting at 195° to 196°. When
myrcenol is oxidized with a one per cent. permanganate solution
and then with a chromic acid mixture, it yields laevulinic and
succinic acids.

According to Barbier, myrcene and myrcenol are to be repre-

sented by the formulas,

CH,
C=CH—CH,—CH=C—CH=CH,,.

CH,
Myrcene.

CH
"¢=CH—CH,—CH,—C(OH)—CH=CH,.
CH, |

CH;
Myrcenol.

Characteristic additive products of myrcene can not be prepared
because most reagents seem to polymerize it. Bromine is absorbed
in a somewhat smaller quantity than corresponds to the addition
of six atoms, but this is attributed to the polymerization of the
hydrocarbon. Myrcene is easily oxidized by permanganate with
the formation of succinic acid (Power and Kleber).

1p. Barbier, Compt. rend., 132, 1048.

ANHYDROGERANIOL. 379

Dihydromyrcene,’ C,,H,,, is formed by reducing myrcene with
alcohol and sodium ; it boils at 171.5° to 173.5°, has the specific
gravity 0.7802, and the refractive index, np = 1.4501. On oxi-
dation with permanganate, it yields laevulinic acid and a keto-
glycol, C,H,,O,, which, on oxidation with chromic acid, gives rise
to a diketone, C,H,,O,.

Cyclodihydromyrcene,' C,,H,., is produced by treating dihydro-
myrcene with a mixture of acetic and sulphuric acids; it boils
at 169° to 172°, has a sp. gr. 0.828, and a refractive index,
ny, = 1.462. It unites with bromine, forming a dibromide (sp. gr.
1.524), and when oxidized it yields a ketonic acid, C,,H,,O,.

It should also be mentioned that the chemists of Schimmel &
Co.’ have isolated a hydrocarbon, C,,H,,, from basil oil, which
boils at 73° to 74° (22 mm.), has the sp. gr. 0.794 at 22° and
0.801 at 15°, and the index of refraction, np = 1.4861. It is
optically inactive, has an agreeable odor, and is termed ocimene.
The properties of ocimene resemble those of myrcene, but it differs
from the latter in its behavior towards oxygen ; it readily absorbs
oxygen and becomes resinified. The examination of ocimene is
not complete.

2, ANHYDROGERANIOL, C,,H,,.

Anhydrogeraniol was the first known representative of the class
of olefinic terpenes. It is formed by heating geraniol, C,,H,,OH,
in small portions at a time with twice its weight of acid potassium
sulphate at 170°. When the reaction-product is distilled in a
current of steam, an oil results, which, after purification by re-
peated distillation over sodium, boils at 172° to 176° (uncorr.).
This oil consists of anhydrogeraniol, C,,H,,; it has a peculiar
smell, a specific gravity 0.8232 and refractive power, np = 1.4835,
at 20°. It yields a hydrocarbon, C,,H.,,, by reduction, and unites
with bromine, forming the compound, C,,H,,Br, (Semmler °*).

No additional observations seem to have been made by Semmler
regarding the behavior of this terpene. However, his assumption
that it contains three double linkages, as indicated by its molecu-
lar refraction, is in harmony with the fact that it combines with
six bromine atoms or six atoms of hydrogen, forming addition-
products.

In the same preliminary publication,? Semmler mentions that
similar olefinic terpenes are obtained from linalool and coriandrol
by treatment with acid potassium sulphate as above described.

iSemmler, Ber., 34, 3122.
2Schimmel & Co., Semi-Annual Report, April-May, 1901, 12.
3Semmler, Ber., 24, 682.

380’ THE TERPENES.

3. OLEFINIC TERPENES IN OIL OF HOPS AND OIL OF
ORIGANUM.

Investigations of Chapman’ on the oil of hops, and of Gilde-
meister’ on the oil of origanum from Smyrna indicate that these
oils also contain olefinic terpenes. On fractional distillation both
oils yield small quantities of a fraction which has the same
boiling point as pinene, but is distinguished from the ordinary
terpenes by its remarkably low specific gravity. Nothing further
‘is known at present regarding these hydrocarbons.

4, LINALOLENE, C,,H,,.

Linalolene is obtained by reducing linalool with sodium and
alcohol, or better by heating equal weights of linalool and zine —
dust in sealed tubes at 220° to 230°; the resultant hydrocarbon __
is purified by distillation with steam, and by subsequent distilla-
tion over sodium. It boils at 165° to 168°, has a specific
gravity 0.7882 and a refractive power, np = 1.455, at 20°
(Semmler *).

The values obtained for the specific and molecular refractive _

powers show that linalolene contains two ethylene linkages, and
therefore belongs to the aliphatic series. When gently warmed
with concentrated sulphuric acid, linalolene undergoes a trans-
formation into an isomeric hydrocarbon, which boils at 165° to
167°, has the sp. gr. 0.8112 and the index of refraction, np =
1.4602, at 17°. Semmler considers this isomeride as a hydro-
benzene derivative, and calls it cyclolinalolene.

OBTAINED FROM MENTHONYL-
AMINE,

5. HYDROCARBON, C,,H

18?

When menthonylamine is treated with nitrous acid in the prep-
aration of menthocitronellol, C,,H,,OH, a by-product is formed
which contains a hydrocarbon, C,,H,,. It boils at 153° to 156°,
has the specific gravity of 0.7545 at 15°, and a refractive power,
ny = 1.4345 (Wallach *).

1Chapman, Jour. Chem. Soc., 1894, 1, 54; Ber., 28, 303, Ref.
2?Gildemeister, Arch. Pharm., 233, 182.

3Semmler, Ber., 27, 2520.

4Wallach, Ann. Chem., 278, 317.

LINALOOL. 381

B. OXYGENATED COMPOUNDS.
(2) ALCOHOLS.
1. LINALOOL, C, mo Oi ,OH.

Morin! showed that the oil of linaloe contains an alcohol,
C,,H,,OH, which Semmler? in the year 1891 identified as an
aliphatic terpene alcohol ; he called it linalool. In the following
year Barbier* submitted ‘linalool, prepared from oil of linaloe, to
a detailed investigation, and designated this alcohol as “licareol.”
Barbier at first doubted the identity of his ‘licareol”’ and lina-
lool, but subsequently recognized that they were identical.‘

Linalool is very widely distributed in nature. Simultaneous
with Semmler and Tiemann,’ Bertram and Walbaum® found
linalool and linaloy] acetate in ‘the oil of bergamot. The alcohols,
C,,H,,OH, which Semmler and Tiemann ® called “ aurantiol” and
o lavendol, and which occur partially in a free condition and
partially in the form of fatty acid esters in the oil of petitgrain
and in lavender oil, are to be regarded as linalool (Bertram and
Walbaum °). In a subsequent publication, Tiemann and Semm-
ler’ assented to the views expressed by Bertram and Walbaum
and added that the alcoholic constituent of the oil of neroli, the
so-called “nerolol,” is in all probability to be regarded as linalool.
According to Reychler, linalool is also found in oil of ylang-
ylang® and in oil of cananga’; according to Gildemeister,” it
occurs together with levorotatory linaloyl acetate in oil of limes
(Citrus limetta Risso), and likewise in Smyrnan oil of origanum.
Linaloyl acetate is found in sage oil (Salvia sclarea L.).

1-Linalool, partly free, partly as ester, forms a constituent of
Palermo lemon oil, spike oil, thyme oil,” Russian spearmint oil,
German ” and French ™ basilicum oil, and sassafras leaf oil.

'™Morin, Ann. Chim. Phys. [5], 25, 427.

2Semmler, Ber., 24, 207.

5’Barbier, Compt. rend., 114, 674; Ber., 25, 463, Ref.

4Barbier and Bouveault, Compt. rend., 121, 168.

5Semmler and Tiemann, Ber., 25, 1180.

6Bertram and Walbaum, Journ. pr. Chem. [2], 45, 590.

7Tiemann and Semmler, Ber., 26, 2708.

8Reychler, Bull. Soc. Chim. [3], 11, 407 and 576; Ber., 27, 751, Ref.;
28, 151, Ref.

9Reychler, Bull. Soc. Chim. [3], 17,.1045.

10Gildemeister, Arch. Pharm., 233, 174.

1lLabbé, Bull. Soe. Chim., 79 [III.], 1009; Schimmel & Co., Semi-Annual
Report, Oct., 1894, 57.

12Bertram and Walbaum, Arch. Pharm., 235, 176.

13Dupont and Guerlain, Compt. rend., 124, 300.

382 THE TERPENES.

According to our present knowledge, linalool yields no crystal-
line derivative which may be employed for the preparation of a
chemically pure product from the above-mentioned ethereal oils.
Therefore, linalool is separated by the fractional distillation of
these oils ; but oils which contain esters of linalool, together with
the free alcohol, must first be treated with alcoholic potash, and
then rectified. The properties of linalool so prepared vary in

certain respects according to its origin.

rendered apparent by the following table.

LINALOOL OBTAINED FROM,

These variations are

Lavender | Bergamot | Linaloe : Oil Oil of
Oil Oil Linaloe | ofLimes | Origanum
Sth (Bertram (Bartram ( Semmaler) 2| (Gilde- (Gilde-
Walbaum ).2 athens ).4|Walbaum).? meister).? | mentee
Boiling point. 197° to | 197° to | 197° to | 195° to | 198° to | 197.8° to ©
199° 199° 200° 199° 199° 199°
under under
760 mm.| 752mm,
Specific gravity. | 0.8725 at | 0.8720 at | 0.8770 at | 0.8702 at | 0.870 at | 0.8704 at
15° 15° 15° 20° 15° 15°
Refractive 1.4640 at | 1.4629 at | 1.4630 at | 1.4695 at | 1.4668 at | 1.4633 at
index, np. 20° 18° 20° 20°° 20° 20°
Angle of rotation} —10°35’ | -—16° —2° —17°37’ | —15°56/
(100 mm. ). at 15° at 15°

The difference in the properties of these various samples of lin-

alool was at times explained by the supposition that they con-

tained different, although closely allied, alcohols. Recently,

however, all these alcohols have been regarded as identical, and

the anomalies in their properties as being dependent on the pres-
ence of impurities ; this view is rendered more probable by the
fact that they exhibit exactly the same chemical behavior. If
linalool, obtained from any of the above-mentioned oils, be oxi-
dized with chromic acid, it is converted into an optically inactive
aldehyde, geranial (citral), C,,H,,O, which is characterized by its
transformation into cymene, and by the formation of the crystal-_
line geranial (citral)-$-naphthocinchonic acid, melting at 198° to
199°.

All alcohols of the formula, C,,H,,OH, having the properties
given in the above table, are termed linalool if they are optically

1Bertram and Walbaum, Journ. pr. Chem. [2], 45, 590.
2Semmler, Ber., 24, 207.
3Gildemeister, Arch. Pharm., 233, 174.

LINALOOL. 383

levorotatory, and yield geranial on oxidation. If this definition
of linalool be accepted, then an optically dextrorotatory alcohol,
which Semmler’ called “ coriandrol,” must be designated as der-
tro-linalool. ‘This compound occurs in oil of coriander, and has
the properties of linalool ; it boils at 194° to 198°, has the spe-
cific gravity 0.8679 and refractive index, np = 1.4652, at 20°,
and is converted into geranial by oxidation ; its optical rotation
is reported as [a], = + 13° 19’ and + 15° 1’.

It is of course possible with the increase of knowledge respect-
ing this group of compounds, that the various alcohols, which we
designate at present as linalool, will be distinguished from one
another, and characterized as chemical individuals. Theoretic-
ally, numerous isomerides of geranial may be predicted. As Tie-
mann and Semmler have indicated, a transposition of the ethylene
linkages may take place in such substances by treatment with
certain reagents, and this has been especially observed by Fittig ;
hence, the formation of the same geranial from isomeric alcohols
could be explained by the acceptance of a similar hypothesis.
One observation seems to point to the fact that an intramolecular
change of this nature takes place in linalool. When linalool is
heated with acetic anhydride, it is rendered inactive, and is con-
verted into the acetyl derivative of the isomeric, inactive alcohol,
geraniol. Geraniol boils 30° higher than linalool, and, there-
fore, can not have the same connection with the latter compound
as dipentene with limonene. In consideration of the results ob-
tained by the oxidation of these alcohols, Tiemann and Semmler”
represent the transformation of linalool into geraniol by the fol-
lowing formulas :

cH,—¢ = CH—CH,—CH,—¢ (OH)—CH = CH,
CH, CH,

Linalool (dimethy]-2-6-octadiene-2-7-ol-6).

tear =e SO era = CH—CH,OH.
Geraniol (dimethyl-2-6-octadiene-2-6-ol-8).

According to more recent investigations by Barbier,’ this for-
mula for linalool represents the constitution of myrcenol, and

1Semmler, Ber., 24, 206; compare Kawalier, Jahresb. Chem., 1852, 624,
and Grosser, Ber., 14, 2485.

2Tiemann and Semmler, Ber., 28, 2126.

sBarbier, Bull. Soc. Chim., 25 [III.], 828.

384 THE TERPENES.

Barbier therefore suggests that linalool is stereoisomeric with
geraniol (“lemonol’’), and is to be represented by the formula :

sa Ta ra —CH—CH,0H.

H, CH,
Linalool.

According to Barbier, the compound previously regarded as
pure linalool is a mixture of levo-terpineol, active myrcenol and
unsaturated ethers of the formula, C,,H,,O ; and since linalool
has not been obtained free from these substances, the optical rota-
tion of the pure alcohol is not at present known. Barbier re-
gards pure linalool as inactive, and since the oxidation products
of linalool are identical with those of geraniol, he considers that
all the reactions of linalool are more readily explained by his
formula.

According to Tiemann,' a fairly pure linalool, free from ter-
penes, may be obtained from the essential oils by the following
process. Sodium is added to the crude linalool contained in a
retort, and the liquid is heated under reduced pressure as long as
the sodium continues to be dissolved ; after cooling, the unchanged
metallic sodium is removed, the sodium salt of linalool is suspended
in dry ether, and treated with succinic, or, better, phthalic anhy-
dride. After standing for several days, the liquid is agitated
with water, which dissolves the linaloyl sodiwm phthalate, while
any unchanged linalool or linalolene remains in the ether; the
aqueous solution is repeatedly washed with ether, the solution is
acidified, and again extracted with ether. The resulting linaloyl
acid phthalate is hydrolyzed with alcoholic potash, and the puri-
fied linalool is extracted with ether.

An inactive linalool may be artificially prepared by heating
geraniol with water in an autoclave for some time at 200° ; it
boils at 198° to 200° (753 mm.), and has the sp. gr. 0.877 at
15°.’ Another method of preparing inactive linalool consists in
treating geraniol with hydrochloric acid, and saponifying the re-
sultant, isomeric chlorides, C,,H,,Cl, with alcoholic potash ; some
geraniol is regenerated, and about fifty per cent. of inactive
linalool is obtained (Tiemann*). According to Stephan,* a third
method of converting geraniol into inactive linalool consists in

1Tiemann and Kriiger, Ber., 29, 901; Tiemann, Ber., 31, 837.
2Schimmel & Co., Semi-Annual Report, April, 1898, 27.
3Tiemann, Ber., 31, 832.

4Stephan, Journ. pr. Chem., 60 [II.], 252.

LINALOOL, 385

passing steam into an aqueous solution of sodium geranyl phtha-.
late ; some geraniol is also regenerated.

It is reported that levo-linalool may be converted into dextro-
linalool by the influence of acid reagents'; thus, this transforma-
tion is said to take place on heating a solution of linaloyl acid
phthalate, and during the preparation of linaloyl acetate by the
action of acetic and dilute sulphuric acids on linalool.

Linalool absorbs four atoms of bromine. When reduced with
sodium and alcohol, or when heated with zine dust at 220° or 230°,
it is converted into linalolene, C,,H,,(Semmler). By the action
of hydrochloric acid on linalool, water is eliminated, and a mixture

‘of liquid chlorides, C,,H,,Cl,, results ; they decompose when dis-

tilled in vacuum (Bertram and Walbaum).

According to Barbier,? when this mixture of chlorides is heated
with potassium acetate and glacial acetic acid, terpenes, geranyl
acetate and geraniol are formed.

The action of dehydrating agents on linalool has been studied
by Bertram and Walbaum. Water may be removed by acid
potassium sulphate or by dilute sulphuric acid. When linalool is
heated gently with formic acid of sp. gr. 1.22, a somewhat violent
reaction takes place, and water is very readily separated with the
formation of terpinene and dipentene; this reaction is worthy of
special notice, since by means of it the first transformation of an
aliphatic compound into a true terpene, C,,H,,, was effected. Ac-
cording to Semmler, aliphatic terpenes may also be obtained from
linalool, but nothing definite has been published regarding such
compounds. (See anhydrogeraniol.)

When formic acid is allowed to act on levo-linalool at a tem-
perature below 20°, fifty per cent. of the linalool is converted into

- dextro-terpineol ; in the same manner, formic acid converts dextro-

linalool (coriandrol) into levo-terpineol (Stephan *).

When I-linalool is warmed with acetic acid, some d-terpineol is
produced. Cold acetic acid does not act upon it, but if a solution
of linalool in three times its weight of acetic acid be treated with
one half a per cent. of sulphuric acid at a temperature below 20°,
about forty-five per cent. is changed into d-terpineol, and ten per
cent. into geraniol (Stephan *).

Hydrogen peroxide converts linalool into a crystalline com-
pound, melting at 110° to 111° ; this substance has been shown to

1Schimmel & Co., Semi-Annual Report, Oct., 1896, 85; compare with
Charabot, Bull. Soc. Chim., 21, 549.

2Barbier and Bouveault, Bull. Soc. Chim., 15 [III.], 594.

8Stephan, Journ. pr. Chem., 58 [II.], 109.

25

386 THE TERPENES.

be identical with terpine hydrate, the formation of which is prob-
ably due to the presence of a mineral acid impurity in the reagent
(Bertram and Walbaum).

Terpine hydrate is almost quantitatively formed, when linalool
is agitated with five per cent. sulphuric acid for several days.’

Chromic acid oxidizes linalool into the aldehyde geranial
(citral). The oxidation sometimes proceeds further, yielding oxida-
tion products of geranial, as methyl heptenone, laevulinic acid, ete.

Tiemann and Semmler? obtained rather remarkable results in
the oxidation of linalool. By successive treatment with potas-
sium permanganate and chromic acid, they accomplished quite
readily a decomposition of this alcohol into acetone, laevulinic
acid and oxalic acid. They concluded, therefore, that linalool
contains the grouping,

C(CH,), = CH — CH, — CH, — C(CH,) =;

and considering that it must also contain an asymmetric carbon
atom, they derived the formula of linalool which has already
been presented.

The alcohol obtained from coriander oil, which must be desig-
nated as dextro-linalool, yields compounds, C,,H,,Cl and C,,H,,I,
when treated with hydrochloric and hydriodic acids ; these sub-
stances are oils which can not be distilled. When dextro-linalool
is oxidized with permanganate, it is converted into a ketone,
C,,H,,O, carbonic anhydride, acetic acid and a gelatinous acid,
having the constitution C,H,,O, (Grosser °).

Linaloyl acetate, C,,H,,OCOCH,, is found in many ethereal
oils, especially in the oil of orange blossoms and in the oil
of bergamot, whose odor is dependent on it. It is formed when
myrcene is treated with a mixture of glacial acetic and sulphuric
acids (Power and Kleber *).

In order to prepare it, linalool is boiled with acetic anhydride
for several hours, the product is washed with water and soda
solution, and the ester distilled with steam. The terpenes which
result during its preparation are separated by fractional distil-
lation in vacuum (Bertram and Walbaum).

Linaloyl acetate has a strong odor of bergamot, and boils and
decomposes at 220° when distilled under ordinary pressure. It

boils at 105° to 108° under a pressure of 11 mm., and has the

1Tiemann and Semmler, Ber., 28, 2137.

2Tiemann and Semmler, Ber., 28, 2126.

3Grosser, Ber., 14, 2494 and 2497.

4Power and Kleber, Pharm. Rundsch, 1895, No. 13; A. Hesse, Journ. pr.
Chem., 64 [II.], 245.

GERANIOL. 387

specific gravity 0.912 at 15°; [a],—= — 6° 25’. Alcoholic pot-
ash changes it into linalool.

Pure linaloyl acetate may be prepared from sodium linaloolate
and acetic anhydride; it boils at 96.5° to 97° under 10 mm.
pressure (Hesse).

If the acetate be prepared from levo-linalool by means of a
mixture of glacial acetic and sulphuric acids, dextro-linaloyl
acetate is obtained; this yields dextro-linalool when saponified
(Gildemeister ').

Linaloyl propionate, C,,H,,OCOC,H,, is a fragrant oil, which
boils at 115° under 10 mm. pressure. It occurs naturally in
lavender oil.

Linaloyl butyrate occurs in lavender oil, and the valerianate is
contained in lavender oil and sassafras oil.

It is to be noted that the esters of linalool, which are prepared
synthetically by heating linalool with acid anhydrides, are not
chemically pure compounds ; they consist largely of the esters of
linalool, together with some esters of geraniol and terpineol, and
are usually optically inactive or slightly dextrorotatory. The
naturally occurring esters are levorotatory.

2. GERANIOL, C,,H,,OH.

Geraniol is an alcohol closely related to linalool, but is distin-
guished from it by its optical inactivity and by its higher boiling
point (linalool boils at 197° to 200°, geraniol at 229° to 230°),

The conversion of linalool into geraniol was first observed by
Barbier.” This chemist found that the boiling point of linalool
increases and its optical rotatory power decreases when it is heated
with acetic anhydride at 120° fora long time; the resultant alco-
hol, having a rose-like odor, was thought to be different from
geraniol, and was called “licarhodol.” Bouchardat* at once ex-
pressed the opinion that this licarhodol was identical with geraniol.
The correctness of Bouchardat’s statement was conclusively
proved by Bertram and Gildemeister* by the isolation of the cal-
cium chloride compound of geraniol from Barbier’s licarhodol.

1Gildemeister, Arch. Pharm., 233, 174; German Patent, No. 80,711; com-
pare with Tiemann and Semmler, Ber., 25, 1184 and 1187; Bertram and
Walbaum, Journ. pr. Chem., 45 [II.], 598.

2Barbier, Compt.,rend., 116, 1200; Ber., 16, 490, Ref.

3Bouchardat, Compt. rend., 116, 1253; compare Barbier, Compt. rend.,
117, 122.

4Bertram and Gildemeister, Journ. pr. Chem. [2], 49, 185; compare
Stephan, Journ. pr. Chem. [2], 58, 109; Schimmel & Co., Semi-Annual Re-
port, April, 1895, 33.

388 THE TERPENES.

Tiemann and Semmler' also confirmed Bouchardat’s view, and
Barbier and Bouveault? have admitted its accuracy.

Geraniol is widely distributed in nature. Indian oil of geran-
ium and palmarosa oil contain ninety-two per cent. of geraniol
as shown by the experiments of Jacobsen * and, more recently, by
those of Semmler.* It has also been found in pelargonium oil
(African geranium oil) by Gintl,’ and in the oil of citronella by
Schimmel & Co.° It occurs in the oil of Eucalyptus maculata,
var. citriodora, and occurs, together with linalool, in lavender oil,
lemon grass oil and ylang-ylang oil. It is also found in small
quantities in neroli and petitgrain oils, oil of spike, lignaloe oil,
and sassafras oil. According to Smith,’ the oil from the fresh
leaves and branchlets of Eucalyptus macarthuri contain sixty
per cent. of geranyl acetate, 10.64 per cent. of free getenes, as
well as some eudesmol.

Of especial interest, however, is the fact that the greatest part
of the alcoholic constituents of Turkish and German oil of rose
consists of geraniol (Bertram and Gildemeister ° ).

In an investigation of the oil of rose, Eckart’ discovered an
alcohol, C,,H,,O, to which he gave the name “rhodinol.”” Mark-
ownikoff and Reformatzky ” examined rose oil and came to: the
conclusion that it contained an alcohol, C,,H,O, which they
called ‘‘roseol” ; Barbier" rejected this conclusion, and confirmed
Eckart’s observations. Tiemann and Semmler! further de-
termined that ‘‘rhodinal,” C,,H,,O, which is obtained by the
oxidation of Eckart’s “rhodinol,’ C,,H,,O, is identical with
garanial, C,,H,,O. The conclusive proof that rose oil contains
geraniol was given by Bertram and Gildemeister by the isolation
of the calcium chloride compound of geraniol from rose oil. More
recent investigations have proved that rose oil’? and the ethereal

1Tiemann and Semmler, Ber., 26, 2708.

?Barbier and Bouveault, Compt. rend., 121, 168.

3Jacobsen, Ann. Chem., 157, 232.

4Semmler, Ber., 23, 1098.

5Gintl, Jahresb. Chem., 1879, 941.

6Semi-Annual Report of Schimmel & Co., Oct., 1893, and German Patent,
No. 76,435; Ber., 27, 953, Ref.; compare Journ. pr. Chem. [2], 49, 191, and
Dodge, Amer. Chem. Journ., 1889, 456; Ber., 23, 175, Ref.

7H. G. Smith, Chem. News, 83, 5

8Bertram and Gildemeister, Journ. pr. Chem. [2], 49, 185; Gildemeister
and Stephan, Arch. Pharm., 234, 321.

9Eckart, Arch. Pharm., 229, 355.

Markownikoff and Reformatzky, Journ. pr. Chem. [2], 48, 293; Ber.,
27, 625, Ref.

11Barbier, Compt. rend., 117, 177 and 1092.

12Dupont and Guerbain, Compt. rend., 123, 700.

GERANIOL, ‘389

oils of the genus Pelargonium contain geraniol, C,,H,,O, together
with considerable quantities of another alcohol, citronellol, C,,H,,0.

The terpene alcohol “ réuniol,” prepared ‘by A. Hesse! from
Réunion geranium oil by means of its Pa acid ester, has
been shown to be a mixture? of geraniol, C,,H,,O, and citronellol,
C,,H,,O.

“Erdmann and Huth® suggested that the name “rhodinol” be
substituted for that of geraniol ; this suggestion, however, can not
be accepted.

Barbier and Bouveault * obtained an alcohol from the volatile
oil of Andropogon schenanthus; they considered it an individual
chemical compound, and called it “lemonol.’”’ Bertram and Gil-
demeister’ have proved that this “ lemonol ” is a mixture, contain-
ing considerable quantities of geraniol.

Very different opinions have been expressed from time to time
by different chemists regarding the constituents of the above-men-
tioned essential oils, and the nature of the alcohols obtained from
them. The use of different names for geraniol and citronellol, or
for mixtures of these two alcohols has led to considerable con-
fusion in the study of these compounds and their derivatives. It
must suffice here merely to note that the recent investigations,
especially those of Bertram and Gildemeister, ° chemists of Schim-
mel & Co., Leipzig, have practically proved that geraniol, C,,H,,O,
is identical with ‘“lemonol” (Barbier and Bouveault), and with
“rhodinol” (Erdmann and Huth, and Poleck); citronellol,
C,,H,,O (Tiemann and Schmidt) is identical with “ rhodinol »
of Barbier and Bouveault and with “ réuniol” (Hesse, Naschold) ;
Eckart’s “ rhodinol” is a mixture of geraniol and citronellol, and
the same may be said of ‘“ roseol ” (Markownikow) ; “ licarhodol ”
(Barbier) is a mixture of about eighty-five parts of geraniol and
fifteen parts of dextro-terpineol.

1A. Hesse, Journ. pr. Chem., 50 [II.], 474; 53 [II.], 23; Wallach and
Naschold, Naschold’s Inaug. Diss., Géttingen, 1896.

Schimmel & Co., Semi-Annual Report, April, 1895, 37 and 63; Tiemann
and Schmidt, Ber., 29, 903.

8Erdmann and Huth, Journ. pr. Chem., 53 [II], 42; 56 [II], 1; Poleck,
Ber., 31, 29; Journ. pr. Chem., 56 [II.], 515; Bertram and Gildemeister,
Jouts. pr. Chem; 56 [II.J, 506.

‘Barbier and Bouveault, Compt. rend., 118, 1154 and 1208; 119, 281
and 334; 122, 393; Bull. Soc. Chim., 15 III. ], 594; Barbier, Compt. rend.,
126, 1423; Teminni. Ber., 31, 2989; Barbier, Bull. Bos. Chim., 27 [IIL], 635.

5Bertram and Gildemeister, Journ. pr. Chem., 53 [II.], 225; Schimmel
& Co., Semi-Annual Report, April, 1898, 33.

6 Schimmel & Co., Semi-Annual Report, April, 1896, 37; Oct., 1896, 85,
87 and 90; April, 1897, 32; Oct., 1897, 67; Oct., 1898, 55.

390 THE TERPENES.

In order to prepare geraniol, the oils which contain large quan-
tities of this alcohol are treated with alcoholic potash to remove
esters, and are then fractionated in vacuo. The resulting gera-
niol, however, generally contains impurities. The method for the
purification of this product depends on the property observed by
Jacobsen’ that geraniol combines with calcium chloride. Ac-
cording to Bertram and Gildemeister,’ the crude geraniol is care-
fully dried and intimately mixed with an equal amount of freshly
dried and finely pulverized calcium chloride ; the mixture is al-
lowed to stand in a desiccator at a temperature of — 4° to — 5°
for twelve to sixteen hours. The resultant, more or less tough,
mass is rubbed up with anhydrous benzene or petroleum ether,
and filtered with the pump. The substance remaining on the
filter is again mixed with benzene and filtered, the same process
being repeated for a third time; the product is then decomposed
with water. The oil which separates is washed with water and
distilled, the geraniol boiling at 228° to 230°. As a rule the
separation of geraniol by this method is only applicable when
the ethereal oil contains at least twenty-five per cent. of geraniol.
Chloride of magnesium, and calcium or magnesium nitrate also
form crystalline additive compounds with geraniol, and may be
used in place of calcium chloride.

Several other methods * have been proposed for the separation of
geraniol from mixtures with terpenes, etc., depending on the pro-
duction of an acid geranyl ester by the action of succinic, or, pref-
erably, phthalic anhydride on the sodium salt of crude geraniol,
or by heating geraniol with phthalic anhydride on the water-
bath. This acid ester or its sodium salt (prepared from the pure
silver salt) is saponified with alcoholic potash, and a very pure
geraniol is obtained. These methods have no great superiority
over the calcium chloride process.

PROPERTIES.—Geraniol is an optically inactive alcohol, which
has a very pleasant odor of roses, and boils at 229° to 230°
under atmospheric pressure and at 120.5° to 122.5° under a
pressure of 17 mm. Its specific gravity at 15° is 0.8801 to
0.8834, according to its origin ; the refractive power is np = 1.4766
to 1.4786. The specific gravity of geraniol increases rapidly when
it is allowed to stand in the air (Tiemann and Semmler*).

1Jacobsen, Ann. Chem., 157, 232.

2Semi-Annual Report of Schimmel & Co., 1895, 38.

‘Tiemann and Kriiger, Ber., 29, 901; Haller, Compt. rend., 122, 865;
Erdmann, Journ. pr. Chem., 56 [II.], 17; Flatau and Labbé, Compt. rend.,
126, 1725; Bull. Soe. Chim., 19 [III.], 635.

‘Tiemann and Semmler, Ber., 26, 2711.

GERANYL BROMIDE DIHYDROBROMIDE. 391

Jacobsen recognized geraniol as an alcohol, and prepared ger-
anyl chloride, C,,H,,Cl, geranyl bromide and iodide by the action
of the halogen hydrides on geraniol; he described these com-
pounds as oils which could not be distilled, and further stated
that their halogen atoms could be replaced by sulphur, oxygen and
acid radicals.

According to Reychler,' when geraniol is saturated with hy-
drogen chloride, the compound, C,,H,,Cl,, is formed ; when this
substance is boiled with water, it yields a product intermediate be-
tween C,,H,,Cl, and C,,H,,O.

Isomeric chlorides, C,,H,,Cl, are probably produced by the
action of hydrogen chloride on geraniol; they are converted into
geraniol and linalool by the action of alcoholic potash.”

Geranyl bromide dihydrobromide,*> C,,H,,Br-2HBr, is formed by
the action of hydrobromic acid on geraniol in glacial acetic acid
solution ; it decomposes on distillation. Silver acetate converts
it into geranyl acetate and a diacetate of a glycol, C,,H,,(OH),.

According to Semmler, geraniol absorbs four atoms of bromine
or iodine.

The conversion of geraniol into the isomeric linalool was men-
tioned under linalool. On the other hand, linalool may be con-
verted into a mixture of geraniol and dextro-terpineol or its ace-
tate (Barbier’s “licarhodol”) by heating with acetic anhydride.*

On heating geraniol with water in an autoclave at 240° to
250°, it is decomposed into hydrocarbons (dipentene).*

Geraniol is more stable towards acids than linalool. Boiling
acetic anhydride converts it quantitatively into geranyl acetate ;
no terpineol is formed during this reaction. Acetic acid con-
taining one to two per cent. of sulphuric acid converts it into
- terpineol.®

Formic acid acts on geraniol at 0° to 5° yielding geranyl
formate ; on warming, terpinene is produced; at 15° to 20°,
however, the product consists chiefly of terpinyl formate, which
yields terpineol (m. p. 35°) on hydrolysis (Stephan).

When geraniol is shaken with a five per cent. sulphuric acid
for several days, terpine hydrate is formed.°

1Reychler, Bull. Soc. Chem., 15 [III.], 364; Barbier and Bouveault,
Bull. Soe. Chim., 175 [III.], 594.

2Tiemann, Ber., 31, 808.

3Naschold, Inaug. Diss., Géttingen, 1896.

sBouchardat, Compt. rend., 116, 1253; Stephan, Journ. pr. Chem., 58
PS)

5Stephan, Journ. pr. Chem., 60 [II.], 244.

6'Tiemann and Semmler, Ber., 28, 2137.

392 THE TERPENES.

Semmler found that geraniol is converted into anhydrogeraniol,
an aliphatic terpene, by the action of potassium bisulphate ; dilute
sulphuric acid converts geraniol into terpinene, and concentrated
formic acid gives rise to terpinene and dipentene.' The action
of phosphoric anhydride on geraniol also causes the formation of
terpenes and polyterpenes having a cyclic structure of the carbon
atoms.

Cold solutions of alkalis are without action on geraniol. Ac-
cording to Barbier,” when “lemonol ” (geraniol) is heated with
a concentrated, alcoholic solution of potash at 150° for eight
hours, it yields a tertiary alcohol, C,H,,O, dimethyl heptenol.
According to Tiemann,* however, this reaction gives rise to methyl
heptenol (methyl hexylene carbinol), C,H,,O. On similar treat-
ment, linalool is hardly altered.

On oxidation of geraniol with chromic acid, geranial, C,,H,,O,
is produced ; the reaction frequently proceeds further giving oxi-
dation products of geranial. Since the latter compound is an
aldehyde, geraniol must be a primary alcohol. The oxidation of
geraniol with potassium permanganate converts it into isovaleric
acid, see under linalool (Semmler, Jacobsen).

Geraniol, like linalool, is readily decomposed into acetone,
laevulinic acid and oxalic acid by gentle oxidation. If geraniol
(fifty grams) be oxidized in the cold with a very dilute solution of
potassium permanganate (seventy grams), a product results which
is probably a polyvalent alcohol, although it has never been
isolated. ‘This compound is contained in the filtrate from the
manganese oxides, and is in its turn oxidized by heating the
aqueous solution with chromic anhydride (one hundred and fifty
grams) and sulphuric acid (two hundred and fifty grams). The
products of this oxidation are, as above stated, acetone, laevulinic
and oxalic acids. From this reaction, Tiemann and Semmler ‘*
derive the formula for geraniol :

cH,—¢ = CH—CH,—CH,—¢ — CH—CH,OH.

CH, CH,
Dimethy]-2, 6-octadiéne-2, 6-ol-8.

Geranyl acetate, C,,H,,OCOCH., is found, together with gera-
niol, in certain ethereal oils, and may be prepared by boiling gera-

1Bertram and Walbaum (Gildemeister), Journ. pr. Chem., 49 [II.], 185;
53, 236.

2Barbier, Compt. rend., 126, 1423.

3Tiemann, Ber., 31, 2991; Schimmel & Co., Semi-Annual Report, Oct.,
1898, 61 :

4Tiemann and Semmler, Ber., 28, 2126.

MENTHOCITRONELLOL. 393

niol with acetic anhydride (Bertram and Gildemeister). It is de-
composed into the alcohol and acetic acid when distilled under
atmospheric pressure, but boils without decomposition at 127.8°
to 129.2° under a pressure of 16 mm. It has a specific gravity
of 0.9174 and refractive power, n, = 1.4628, at 15°. Since ter-
penes are not formed by boiling geraniol with acetic anhydride,
the determination of the saponification figure may be employed for
the quantitative estimation of geraniol in mixtures of this alcohol
with terpenes.

Other fatty acid esters of geraniol are prepared by the action of
the acid anhydrides on geraniol, or from the acid chlorides and
geraniol in the presence of pyridine. These esters are all liquids.

Geranyl diphenylurethane,! (C,H,),N°CO-OC,,H,., isa compound
well adapted for the characterization of geraniol; it crystallizes
from eighty per cent. alcohol in long, silky needles, melting at
82.2°. It forms a tetrabromide, which melts at 129° to 132°.

Geranyl hydrogen phthalate, C,,H,,O-CO-C,H,-COOH, may be
used for the isolation and preparation of pure geraniol. It was
obtained by Erdmann? as a colorless oil by heating “ rhodinol ”
with finely powdered phthalic anhydride on the water-bath.
According to Flatau and Labbé,’ geraniol may be separated from
citronellol by boiling a mixture of the two alcohols, in a reflux
apparatus, with an equal weight of phthalic anhydride dissolved
in benzene; the resultant ethereal salts are purified, and dissolved
in petroleum ether. On cooling the solution to — 5°, geranyl
phthalate separates in the crystalline form, while on evaporation of
the remaining liquid citronellol phthalate is obtained as a yellow oil.

Geranyl phthalate crystallizes in rhombic tablets, melting at
47°, and is readily soluble in most organic solvents in the cold,
with the exception of petroleum ether. When dissolved in ether
and treated with bromine, it yields tetrabromogeranyl phthalate,
C,,H,,Br,O-CO-C,H,-COOH ; it crystallizes from petroleum ether,
and melts at 114° to 115°.

The silver salt of geranyl phthalate melts at 133°; it is puri-
fied by dissolving in benzene and precipitating with warm methyl
alcohol.

3. MENTHOCITRONELLOL, C,,H,,OH.

As has already been mentioned under menthone, menthonitrile,
on reduction, yields two bases, menthonylamine, C,,H,,NH,, and
oxyhydromenthonylamine, C,,H,(OH)NH,,.

1Erdmann, Journ. pr. Chem., 53 [II.], 42; 56 [II.], 28.

2H. Erdmann and Huth, Journ. pr. Chem., 56 [II.], 17; see Erdmann,

Ber., 31, 356.
3Flatau and Labbé, Compt. rend., 126, 1725.

394 THE TERPENES.

When menthonylamine oxalate (twenty grams) is warmed with
a concentrated solution of sodium nitrite (twelve grams in eighty
grams of water), an oil separates immediately ; it has a rose-like
odor, and may be distilled in a current of steam. This oil con-
tains menthocitronellol (menthonyl alcohol), C,,H,,OH, together
with its nitrous acid ester, and small quantities of a hydrocarbon,

H,, (b. p. 153° to 156°). The ester is removed by treating
with sodium methylate; the reaction-product is distilled with
steam, and the resulting oil is dried over potash, and fractionated
under diminished pressure. The hydrocarbon distills over first,
and is followed by menthocitronellol at 95° to 105° under a
pressure of 7 mm.

This alcohol is an isomeride of menthol, has a specific gravity
0.8315 and refractive index, np = 1. 44809, at 20°; it is feebly
dextrorotatory, [«]p = + 2.008°. In some respects it is similar
to linalool, and, like the latter, it yields an acetate having a ber-
gamot-like odor. When oxidized with chromic anhydride it
yields an aldehyde, menthocitronellal, C,,H,,O ; it is, therefore, a
primary alcohol ( Wallach’).

Menthocitronellol shows considerable similarity to citronellol,
and future investigations may show them to be identical; but for
the present they are to be regarded as individual compounds.

Dimethyl octylene glycol (2, 6-dimethyl octane-2, 8- -ol), C, Bin eS -
(OH),, is formed by the action of nitrous acid on oxyhydromen-
thonylamine, C,,H,,(OH)NH, ; it boils at 153° to 156° (19 mm.),
and is converted into menthocitronellol by the action of dilute

sulphuric acid (Wallach ’).

4, CITRONELLOL, C,,H,,OH.

It has already been mentioned that mixtures of geraniol and an
alcohol, C,,H,,O, have been described under the names of “ rho-
dinol, 93 réuniol,” * and ‘‘roseol.”° These mixtures were ob-
tained from geranium oil and the oil of rose, and were at first
regarded as definite chemical compounds. After it had been
proved that these substances contained geraniol and an alcohol,
C,,H,,O, the terms ‘‘rhodinol” and “ réuniol” were applied to
the latter compound. Owing to the close relation which this
alcohol bears to citronellal, being prepared from the latter com-

1Wallach, Ann. Chem., 278, 315; 296, 129.

2Wallach, Ann. Chem., 296, 120.

3Eckart, Archiv. d. Pharm., 229, 355; Barbier and Bouveault, Compt.
rend., 119, 281 and 334; 122, 529.

4A. Hesse, Journ. pr. Chem., 50 [II.], 472.

5Markownikow, Journ. pr. Chem., 48 [II.], 293.

re

CITRONELLOL. 395

pound by reduction, Tiemann and Schmidt! proposed the name
citronellol.

Citronellol occurs in the geranium oils in two optically active
modifications, while rose oil appears to contain only levo-citro-
nellol ; esters of citronellol are also found in nature.

It was not until quite recently that a pure citronellol was
obtained, and characterized as a chemical compound. The chief
difficulty was to separate it from geraniol, since the two alcohols
can not be separated by fractional distillation. Wallach and
Naschold? obtained pure l-citronellol by heating a mixture of
this aleohol and geraniol with water in an autoclave at 250°; by
this treatment geraniol is entirely decomposed into hydrocarbons,
while citronellol remains unaltered. According to Tiemann and
Schmidt, citronellol may be separated from geraniol by heating
the mixture with phthalic anhydride at 200° for two hours;
geraniol is thus converted into hydrocarbons, and the resulting
liquid phthalic acid salt of citronellol is separated, washed and
saponified. When phosphorus trichloride is allowed to act on a
mixture of the two alcohols in ethereal solution, it converts
geraniol into hydrocarbons and gerany! chloride ; citronellol, how-
ever, gives rise to a chlorinated acid phosphoric acid ester, which
dissolves in alkalis, and may thus be separated (Tiemann and
Schmidt). Flatau and Labbé convert the mixture of the two
alcohols into the acid phthalic esters ; the geraniol derivative is
crystalline (m. p. 47°), while the citronellol compound is an oil
(see under geraniol).

Dextro-citronellol may be prepared by reducing the corre-
sponding aldehyde, citronellal, with sodium amalgam and glacial
acetic acid.* When obtained by this method, it boils at 117° to
118° under 17 mm. pressure, has the specific rotatory power,
[a]>= + 4°, the sp. gr. 0.8565 and the refactive index, ny =
1.45659 (Tiemann and Semmler),.

According to Wallach, citronellol (‘ réuniol”’) boils at 114° to
115° (12 to 13 mm.), has the sp. gr. 0.856 at 22°, n,= 1.45609
at 22°, and [a],=— 1°40’.

Citronellol is a colorless liquid, has a pleasant, rose-like odor,
and boils at 225° to 226° under a pressure of 764.5 mm.

It is not acted upon by heating with alkalis, but when agitated
with a ten per cent. sulphuric acid, it unites with one molecule of
water, yielding a diatomic alcohol; the latter is a colorless oil,

1Tiemann and Schmidt, Ber., 29, 921.

2Naschold, Inaug. Diss., Géttingen, 1896. :

3Dodge, Amer. Chem. Journ., 11, 463; Tiemann and Schmidt, Ber.,
29, 906.

396 THE TERPENES.

boils at 144° to 146° (10 mm.), and is reverted into citronellol
on treatment with dehydrating agents (Tiemann and Schmidt).

Although citronellol occurs in the ethereal oils with geraniol,
and appears to bear a close relation to the latter alcohol, the re-
duction of geraniol, C,,H,,O, to citronellol, C,,H,,O, has not yet
been accomplished.

Oxidation with chromic acid converts citronellol into the alde-
hyde, citronellal ; the former is, therefore, a primary alcohol. This
oxidation frequently proceeds further, yielding oxidation products
of the aldehyde, as citronellic acid, ete.

When oxidized with a dilute solution of potassium permanga-
nate, citronellol yields a polyatomic alcohol ; if the latter be ox-
idized in turn with chomic anhydride, acetone and -methy] adipic
acid (m. p. 84° to 85°) are obtained. Dextro- and levo--methyl
adipic acid result on the oxidation of the corresponding active
modifications of citronellol ; the inactive -methyl adipic acid erys-
tallizes in needles and melts at 93° to 94°.

According to Tiemann and Schmidt, citronellol is to be re-
garded as dimethyl-2, 6-octene-2-ol-8, and its constitution is rep-
resented by the formula,

CH
DC=CH—CH,—CH,—CH—CH,—CH,OH,
CH,
CH,

The fatty acid esters of citronellol may be readily formed by
treating the alcohol with the corresponding acid anhydrides.

Citronellol acetate, C,,H,,OCOCH., is a colorless liquid, having
a pleasant odor somewhat similar to that of bergamot oil ; it boils
at 119° to 121° (15 mm.), has the rotatory power, [a],=+2° 37’,
the sp. gr. 0.8928, and refractive index, np = 1.4456, at 17.5°.

Citronellol formate boils at 97° to 100° (10 mm.).

Citronellol hydrogen phthalate,’ C,,H,,O-CO-C,H,COOH, is
formed by heating the free aleohol with phthalic anhydride ; it is
a yellow oil. It forms a crystalline silver salt, melting at 120°
to 124°, from which pure citronellol may be regenerated.

Citronellol diphenylurethane ' is a liquid.

(6) ALDEHYDES.

1. GERANIAL (CITRAL), C,,H,,0. »

In the year 1888, the chemists of Schimmel & Co., Leipzig,
determined that lemon oil contains about six to eight per cent. of

1H. Erdmann, Journ. pr. Chem., 56 [II.], 1; Flatau and Labbé, Compt.
rend., 126, 1725.

GERANIAL. 397

an aldehyde, C,,H,,O, and that the characteristic odor of oil of
lemon is due to this aldehyde, which was termed citral.!

Semmler? had also obtained an aldehyde, C,,H,,O, in the oxida-
tion of geraniol ; he then made a careful investigation of citral and
showed that his aldehyde, called geranial, was identical with citral,
hence the two names, citral and geranial, have been employed to
designate thiscompound. Although the name citral is historically
correct, nevertheless geranial is to. be preferred in most instances
since it indicates that this compound is the aldehyde correspond-
ing to geraniol. aint

Geranial has been found in bay oil (Power and Kleber *), in
citronella fruit oil, in cedro oil, in eucalyptus oils of Backhousia
eitriodora and Eucalyptus staigeriana, in lemongrass oil, Japanese
pepper oil of Xanthoxylum piperitum DC, (Schimmel & Co.), and
in the oil of orange peel (Semmler). It also occurs in mandarin
oil, West Indian limette oil, verbena oil, balm oil, pimenta oil,
and the oil of sassafras leaves.

Geranial may be isolated from the ethereal oils by means of its
crystalline acid sodium sulphite compound. It is prepared from
geraniol by the following method (Semmler‘).

Fifteen grams of geraniol are added, all at once, to a solution
of ten grams of potassium dichromate in 12.5 grams of concen-
trated sulphuric acid and one hundred cc. of water; the mixture
is at first well cooled, and afterwards allowed to become warm,
and vigorously shaken for half an hour. The reaction-product is
then made slightly alkaline and distilled in a current of steam ;
the resulting oil is mixed with a solution of acid sodium sulphite,
and allowed to remain for twenty-four hours. The crystals are then
collected, pressed between filter-paper, and decomposed with soda.

' PRoPpERTIES.—Geranial has a specific gravity of 0.8972 at 15°
or 0.8844 at 22°; at the same temperatures its refractive index is
np = 1.934, and n, = 1.486116. It boils at 110° to 112° at
12 mm. pressure, 117° to 119° at 20 mm., and 120° to 122° at
23 mm. Under atmospheric pressure it boils with slight decom-
position at 228° to 229°.

Geranial is a mobile, slightly yellowish oil, having a penetrating
lemon-like odor ; it is optically inactive (Tiemann and Semmler °).
It has the characteristic properties of an aldehyde, reducing a sil-
ver solution, and coloring a fuchsine-sulphurous acid solution.

1¥or the history of citral, compare Tiemann, Ber., 31, 3278.
2Semmleér, Ber., 23, 2965; 24, 201.

3Power and Kleber, Pharm. Rundsch., 1895, No. 13.

4See also Tiemann, Ber., 37, 3311.

5Tiemann and Semmler, Ber., 26, 2708.

398 ' THE TERPENES.

It has been mentioned that, on oxidation with chromic acid,
linalool suffers an intramolecular transformation into geraniol, and
then yields geranial. The latter compound has also been syn-
thetically prepared by Tiemann’ by the distillation of a mixture
of the calcium salts of formie and geranic acids.

Geranial forms a liquid, additive compound with four atoms of
bromine. It is very sensitive towards acids. According to
Semmler,’ geranial is characterized by the great readiness with
which it loses water and is converted into cymene, when heated
with twice its weight of potassium bisulphate for twenty minutes
at 170° ; dilute sulphuric acid also changes it into cymene. Al-
kalis* also decompose geranial; when treated with caustic soda,
it suffers a partial decomposition into methyl heptenone, C,H,,O,
acetaldehyde, and resinous substances. Geranial is converted into
the corresponding primary alcohol, geraniol, on reduction.*

The behavior of geranial towards sodium bisulphite has been
studied by Tiemann and Semmler.° The normal additive com-
pound of geranial and sodium bisulphite, C,H,,,CH(OH):SO,Na,
is formed when geranial (100 parts), sodium thiosulphate (100
parts), water (200 parts), and acetic acid (25 parts) are shaken at
a low temperature ; it is decomposed by dissolving in water, but
may be recrystallized from methyl alcohol containing some acetic
acid ; a quantitative yield of geranial is never obtained from this
compound on treatment with sodium carbonate or caustic soda.
A stable dihydrosulphonic acid derivative of geranial is produced
when the normal compound is submitted to steam distillation, or is
boiled with chloroform, one-half of the geranial being regener-
ated. A labile dihydrosulphonic acid derivative, C,H,,(SO,Na),°
CHO, results when geranial is agitated with sodium sulphite, and
the sodium hydroxide, which is liberated, is neutralized. It is also
formed when the normal crystallized compound is allowed to stand
for some time with an excess of an acid sulphite solution. It is
readily soluble in water, and does not yield geranial on treatment
with alkali carbonates, but is converted into the aldehyde by an
excess of caustic alkalis. It reacts with semicarbazide, forming
sodium geranial semicarbazone dihydrodisulphonate. In the puri-
fication of geranial, it is sufficient to form the Jabile disulphonic
derivative in solution, and then to decompose it with alkali.
Sodium geranial hydrosulphonate results on shaking the labile di-

1Tiemann, Ber., 31, 827.

2Semmler, Ber., 23, 2965; 24, 201; Tiemann, Ber., 32, 107.
3Verley, Bull. Soc. Chim., 17 [III.], 175; Tiemann, Ber., 32, 107.
Tiemann, Ber., 31, 828.

5Tiemann and Semmler, Ber., 26, 2708; Tiemann, Ber., 31, 3297.

GERANYL PHENYLHYDRAZONE. 399

hydrosulphonate with geranial ; it is soluble in methyl alcohol,
and is readily decomposed by sodium hydroxide.

This peculiar behavior of geranial towards sodium bisulphite
solution is obviously similar to the reactions which have been ob-
served with various unsaturated aldehydes and ketones, and which
have been studied in detail by Miiller' in the case of acroléin, and
by Heusler’ and by Tiemann * regarding cinnamic aldehyde.

Geranial- (citral-) 9-naphthocinchonic acid, C,,H,,NO,.—This de-
rivative of geranial, first prepared by Doebner,’ is very charac-
teristic, and especially well adapted for the detection of small
amounts of geranial in ethereal oils. According to this chemist,
aldehydes may be condensed with pyroracemic acid and #-naph-
thylamine, yielding alkyl-$-naphthocinchonic acids ; the geranial
derivative is obtained according to the equation:

B
C,H,;CHO CH,COCOOH oa C,,H,NH,= 2H,0 + H, +

| |
H.
\A
1
COOH.

It is prepared by boiling an alcoholic solution of twenty
grams of geranial, twelve grams of pyroracemic acid and twenty
grams of #-naphthylamine for three hours ; fourteen grams of the
compound are produced. It crystallizes from dilute alcohol in
lemon-yellow leaflets, which contain one-half molecule of water of
crystallization, and melt at 197°.° The hydrochloride of geranial-
8-naphthocinchonic acid crystallizes from alcohol in orange-yellow
needles.

Geranyl phenylhydrazone, C,,H,,N,HC,H,, is an oil, which de-
composes when distilled in a vacuum (Tiemann and Semmler).

The anilide, C,,H,,= NC,H,, is formed by heating geranial
and aniline at 150°; it is a yellow liquid, boiling at 200° under
a pressure of 20 mm.

1Miiller, Ber., 6, 1441.

2Heusler, Ber., 24, 1805.

8Tiemann, Ber., 31, 3297.

4Doebner, Ber., 27, 352 and 2020; 31, 1888 and 3195; compare also
Ber., 31, 3331; 32, 115.

‘The melting point is frequently reported at 200° or slightly above this
point.

400 THE TERPENES.

Dry ammonia also reacts with geranial, yielding an oil which
can not be distilled without decomposition in a vacuum.

Geranialoxime, C,,H,,NOH, is formed by the action of the
molecular amounts of hydroxylamine hydrochloride and soda
on an alcoholic solution of geranial. It is a yellow oil, boils at
143° to 145° under 12 mm. pressure, has a specific gravity of
0.9386 at 20° and an index of refraction, ny = 1.51433. When
the oxime is distilled at atmospheric pressure, water is removed
and the nitrile of geranic acid is produced, together with an
amine which has not been carefully investigated (Tiemann and
Semmler).

Geranial semicarbazones, C,,H,, = N : NHCONH,.—A number
of isomeric semicarbazones appear to have been obtained from
geranial by different investigators. Wallach’ mentions two such
derivatives, melting at 150° and 160°; Tiemann and Semmler?
describe a semicarbazone, melting at 130° to 185°. Barbier and
Bouveault? state that the fraction of the oil of lemongrass (b. p. 107°
to 110° at 10 mm.) yields a semicarbazone, melting at 171°; it
forms white crystals and is very sparingly soluble in boiling aleo-
hol. The fraction of the same oil, boiling at 110° to 112° (10 mm.),
gives three isomeric derivatives, melting at 171°, 160° and 135°,
respectively.

According to more recent investigations by Tiemann,‘ ordinary
geranial yields two isomeric semicarbazones; one is produced in
large amount and melts at 164°, and the other is formed in
small quantity and melts at 171°. A mixture of the low
melting derivative with six to ten per cent. of the other melts
at 135°.

Geranial- (citral-) a.— According to Tiemann,’ ordinary geranial
consists of two geometrical-isomerides termed geranial a and gera-
nial 6. These compounds are separated by converting geranial
into the sodium bisulphite compound, decomposing it with sodium
carbonate, and repeatedly agitating with ether; a portion of the
geranial is changed into the hydrosulphonic acid compound, while
the remainder, about one-half of the total quantity, is dissolved by
the ether. The fraction dissolved in the ether yields exclusively
the semicarbazone, melting at 164°. It is called geranial a. It
boils at 118° to 119° (20 mm.), has the sp. gr. 0.8898, and a

1Wallach, Ber., 28, 1957.

2Tiemann and Semmler, Ber., 28, 2133.
3Barbier and Bouveault, Compt. rend., 121, 1159.
4Tiemann, Ber., 32, 115; 31, 3324.

5Tiemann, Ber., 32, 115; 33, 877.

GERANIC ACID. 401

refractive index, np = 1.4891. Its chemical properties are pre-
cisely like those of ordinary geranial.

Geranial- (citral-) b.—The geranial produced on decomposing the
hydrosulphonic acid derivative referred to under geranial a yields
large amounts of the semicarbazone, melting at 171°, together with
small quantities of the lower melting compound ; it consists, there-
fore, chiefly of geranial 6, and some geranial a. Geranial 6 is
separated from the mixture by means of its compound with cyano-
acetic acid (b-geranialidene cyanouacetic acid, see below) ; the latter
is formed less rapidly than the corresponding a-derivative.

Geranial 6 has the same chemical properties as geranial a; it
boils at 102° to 104° (12 mm.), sp. gr. = 0.888 and np = 1.49001,
at 19°. Its oxime boils at 136° to 138° (11 mm.), its semicarba-
zone melts at 171°, and its /-naphthocinchonic acid melts at
200°.

Geranionitrile, C,H,,CN, is obtained almost quantitatively by
boiling one part of geranialoxime with two and one-half parts of
acetic anhydride for half an hour ; the nitrile is separated by frac-
tionally distilling the reaction-product in vacuum. It boils at 110°
under 10 mm. pressure, has the specific gravity 0.8709 and the
refractive index, np = 1.4759, at 20° (Tiemann and Semmler).

Geranic acid, C,H,,.COOH, is prepared by warming geranial
with moist silver oxide (Semmler'). It may be more conveniently
obtained by boiling geranionitrile with alcoholic potash until am-
monia is no longer eliminated (Tiemann and Semmler’).

It is a colorless liquid, and is readily soluble in alcohol, ether,
benzene, and chloroform ; its odor resembles that of the higher
fatty acids. It boils at 153° (13 mm.), has the specific gravity
0.964 and index of refraction, np = 1.4797, at 20°.

A partial synthesis* of this acid consists in the condensation
of methyl heptenone with ethyl iodoacetate in the presence of
zinc; the product is decomposed with water, yielding a colorless
oil, C,,H,,O,*OC,H,. When this compound is boiled with acetic
acid and some zine chloride, the ethyl ester of geranic acid is
formed ; or, if the acid, C,,H,,O,: OH, corresponding to the com-
pound, C,,H,,O, - OC,H,, is boiled with acetic anhydride, it is con-
verted into geranic acid.

Geranic acid is converted into citronellic acid, C,,H,,O,, when
it is reduced with sodium and amy] alcohol.

1Semmler, Ber., 23, 2965; 24, 201.

2Tiemann and Semmler, Ber., 26, 2708; 28, 2137.

3Barbier and Bouveault, Compt. rend., 122, 393; compare Tiemann, Ber.,
83, 559.

26

402 THE TERPENES.

Geraniolene, C,H,,.— When geranic acid is distilled at the or-
dinary pressure, it decomposes into carbonic anhydride and geranio-
lene; this hydrocarbon is a liquid, boiling at 142° to 143°, has
the sp. gr. 0.757 and the refractive power, np = 1.4368, at 20°.
It forms a liquid tetrabromide, C,H,,Br,.

Geranic acid, geraniolene, and other compounds of the geranial
series may be very readily converted into a mixture of two isomeric
eyclic compounds by the action of dilute acids. The isomerism
of these two classes of compounds is explained by the difference in
position of the double linkage in the ring. They are designated
as a- and -cyclo-compounds; the a-cyclo-geranial derivatives
may be regarded as derived from isogeronic acid or 8, 8-dimethyl
adipic acid, while those of the f-series may be referred back to
geronic acid and a, a-dimethy] adipic acid.’

a- and f-Cyclo-geranic acids," C,H,,COOH.—When geranic
acid is shaken with sixty-five to seventy per cent. sulphuric acid
at 0° for several days, a mixture of the two cyclo-acids, together
with some other products, is formed. After two or three days, a-
cyclo-geranic acid separates from the reaction-product in crystals,
which are filtered, pressed on a plate, and recrystallized from
petroleum ether ; the pure acid melts at 106°. When the liquid
filtrate from the crystalline a-acid is extracted with ether, the
ether evaporated, and the resulting oil repeatedly distilled under
atmospheric pressure, a mixture of a- and §-cyclo-geranic acids is
obtained ; the #-acid can not be separated from this liquid mixture
in a crystalline condition, but its presence may be proved by its
characteristic oxidation products.

A larger yield of 8-cyclo-geranic acid is obtained if geranic
acid is introduced into four parts of concentrated sulphuric acid at
0°, and the mixture is then gradually warmed to 50° and poured
into water. This method, however, does not give a crystalline #-
acid, but that it is formed in considerable quantity is shown by its
oxidation products.

a-Cyclo-geranic acid crystallizes from water or ligroine in
needles, melts at 106°, and boils at 138° (11 mm.); it may also
be distilled without decomposition under atmospheric pressure.
It unites directly with bromine, producing a dibromide which
melts at 121°. Oxidation with potassium permanganate con-
verts the a-acid into diowydihydrocyclogeranic acid, C,H,,(OH),.-
COOH, melting at 198° to 200°, and heto-oxydihydr ocyclogeranic

1Tiemann and Kriiger, Ber., 26, 2693; Tiemann and Semmler, Ber., 26,
2725; Tiemann, Ber., 33, 3703, 3710, 3713, 3719 and 3726; Tiemann and
Schmidt, Ber., 31, 881.

a

a- AND $-CYCLO-GERANIONITRILES. 403

acid, C,,H,,O,, melting at 145°; the latter acid yields a semi-
carbazone, melting at 216°. On oxidizing either the dioxy-acid
or the keto-oxy-acid with one molecular proportion of chromic
acid, isogeronic acid, C,H,,O:COOH, is formed ; this is an open-
chain, ketonic acid, which forms a semicarbazone, melting at 226°.
When the ethyl ester of dioxydihydrocyclogeranic acid is oxi-
dized with chromic acid, it yields the hydrogen ethyl ester of a-
acetyl-8, 2,-dimethyl adipic acid,

ot o/ OH
0
*™"\c000,H; ;

this is an oil, which gives a semicarbazone melting at 157°.
When this ester is heated with an aqueous solution of potassium
hydroxide, it undergoes a ketone hydrolysis and forms isoger-
onic acid.

These oxidation products of a-cyclo-geranic acid indicate that
it is a #, y-unsaturated acid, and that it may be termed methyl-1-
dimethy1-5-cyclohexene-1-methyl-acid-6.

f-Cyclo-geranic acid is formed, as above mentioned, during the
inversion of the aliphatic geranic acid by means of sixty-five to
one hundred per cent. sulphuric acid ; this method, however, does
not give a pure product. The pure acid may be readily formed
by the careful oxidation of £-cyclo-geranial with air or with the
calculated quantity of permanganate in the cold. It crystallizes
from ligroine in large, transparent prisms or plates, and melts at
93° to 94°; it distills undecomposed at atmospheric pressure.
It decolorizes bromine very slowly, yielding hydrogen bromide.
. Its behavior towards oxidizing agents is quite different from that
of the a-cyclo-acid. Oxidation with alkaline potassium perman-
ganate converts f-cyclo-geranic acid into an owy-acid, C,,H,,O,,
which melts with decomposition at 186°, a ketonic acid, C,H,,O,,
which melts at 189° and yields a semicarbazone melting at 240°,
and, as chief product, a, a-dimethy] glutaric acid.

a- and $-Cyclo-geranionitriles,| C,H,,.CN.—A mixture of the
two nitriles is produced by shaking geranionitrile with seventy
per cent. sulphuric acid; a separation of the two nitriles has not
yet been accomplished, but their presence in the reaction-product
is proved by their conversion into the a- and f-cyclo-acids and
their derivatives. The mixture of the two nitriles boils at 87° to

1Tiemann and Semmler, Ber., 26, 2725; Tiemann and Schmidt, Ber.,
$1, 881; Tiemann, Ber., 33, 3705; compare Barbier and Bouveault, Bull.
Soe. Chim., 15 [III.], 1002.

404 THE TERPENES.

88° (11 mm.), has the sp. gr. 0.9208 and the refractive index,
ny = 1.4734, at 20°. It forms an amidowime, melting at 165°,
whilst the corresponding compound of the aliphatic geranionitrile
is a liquid.

a- and $-Cyclo-geraniolenes, C,H,,, cannot be obtained by the
distillation of the corresponding cyclo-geranic acids, but a mixture
of the two hydrocarbons may be prepared by shaking geraniolene
with ten parts of sixty-five per cent. sulphuric acid for three days ;
the yield is sixty to seventy per cent. It boils at 138° to 140°,
has the sp. gr. 0.7978 and refractive index, np = 1.4434, at 22°.

Oxidation with permanganate converts this mixture of a- and
f-cyclo-geraniolenes into isogeronic acid, C,H,,O.COOH, which
gives a semicarbazone melting at 198° and insoluble in ethyl ace-
tate, and geronic acid, C,H,,O.COOH, which yields a semicar-
bazone melting at 164° and readily soluble in ethyl acetate ; geronic
acid’ is an open-chain compound and is also a product of the oxi-
dation of ionone with permanganate.

a- and f-Cyclo-geranials,? C,,H,,0O.—While the compounds of
the geranial series in general yield cyclo-derivatives on the action
of acids, by the union of the carbon atoms in positions 1 and 6
geranial itself is converted intocymene. If, however, the sensitive
aldehyde group in geranial be protected, as in geranialidene cyano-
acetic acid, the normal cyclo-derivatives may be obtained. Thus,
when either a- or b-geranialidene cyanoacetic acid is boiled for
twenty hours with dilute sulphuric acid (1 part of acid to 8 parts
of water), it is converted into the solid cyclo-geranialidene cyano-
acetic acid (a mixture of the a- and #-cyclo-derivatives) ; when
the latter is hydrolyzed with potash, a mixture of a- and f-cyclo-
geranial is formed, of which only the 8-compound has so far been
obtained in a pure condition.

f-Cyclo-geranial is a colorless oil, having the odor of carvone ;
it boils at 88° to 91° (10 mm.) or 95° to 100° (15 mm.), has the
sp. gr. 0.959 at 15° and 0.957 at 20°, and the refractive index,
np = 1.49715, at 15°. Its semicarbazone crystallizes from methyl
alcohol in large prisms containing methyl alcohol and melting at
165° to 166°; it separates from ethyl acetate in thin leaflets
melting at 166° to 167°. By the action of acids, it is quantita-
tively converted into f-cyclo-geranial.

$-Cyclo-geranial forms an additive compound, C,,H,,O,N,, with
semicarbazide, which crystallizes from a mixture of ethyl acetate
and benzene in needles, and melts with decomposition at 250°.

1Tiemann, Ber., 31, 808.
2Tiemann, Ber., 33, 3719; Schmidt, Ber., 34, 2451.

—

GERANIALIDENE BISACETYLACETONE. 405

When f-cyclo-geranial is condensed with acetone, f-ionone is
formed.

8-Cyclo-geranial is readily oxidized into f-cyclo-geranic acid on
exposure to the air. On oxidation with potassium permanganate,
f-cyclo-geranial yields £-cyclo-geranic acid and oxidation products
of this acid, together with geronic acid, C,H,,O,, the methyl
ketonic acid corresponding to a, a-dimethyl adipic acid.

Geranialidene cyanoacetic acid,’ C,H,,- CH = C(CN) - COOH, is
formed when cyanoacetic acid is shaken with geranial in the pres-
ence of aqueous sodium hydroxide; on acidifying the reaction-
mixture, the product separates as an oil which soon solidifies.
The crude product melts at 85° to 90°, but after repeated crys-
tallizations from benzene, it melts at 122°.

It is probable that this compound consists of a mixture of the
cyanoacetic acid derivatives of geranial a and geranial 6. By the
action of dilute sulphuric acid it is converted into the cyclo-
derivative.

6-Geranialidene cyanoacetic acid crystallizes from petroleum
ether in yellowish needles, and melts at 94° to 95°.

Geranialidene bisacetylacetone’ is formed by the condensation of
geranial and acetyl acetone in the presence of a few drops of
piperidine ; it crystallizes from a mixture of alcohol, ether and
ligroine, and melts at 46° to 48°.

Labbé* mentions a polymeride of geranial, (C,,H,,O),, which
results by the action of alcoholic potash on geranial. It melts at
81° to 82°.

It should be mentioned that, according to Stiehl,* lemongrass
oil contains three isomeric aldehydes which he terms “ citriodoral-
dehyde,” “allolemonal” (‘1-licarhodol”’), and “ geranial.” Sub-
sequent investigations by other chemists seem to have indicated
that Stiehl’s three aldehydes are all identical with geranial
(citral).

When geranial is carefully oxidized with a chromic acid mix-
ture or with a glacial acetic acid solution of chromic anhydride at
a very low temperature, methyl hexylene ketone (methyl hepte-
none), C,H,,0, is formed (Tiemann and Semmler’). This ketone is
identical with the compound previously prepared by Wallach by
the distillation of cineolic anhydride. The identity of these two

1Tiemann, Ber., $1, 3324; 33, 877 and 3720; Verley, Bull. Soc. Chim.,
21 [III.], 413 and 414.

2K. Wedemeyer, Inaug. Diss., Heidelberg, 1897.

3Labbé, Bull. Soc. Chim., 21, 407.

4W. Stiehl, Journ. pr. Chem., 58, 51.

5Tiemann and Semmler, Ber., 26, 2708.

406 THE TERPENES.

ketones, C,H,,O, has been determined by Tiemann and Semmler
by the formation of tribromo-methyl hexylene carbinol (tribromo-
heptanonol), C,H,,Br,O-OH ; this substance is produced by the
action of bromine and sodium hydroxide on methyl hexylene ke-
tone, and melts at 98° to 99°.

The ketone, C,H,,O, is likewise obtained by the oxidation of
geraniol, and is also formed as a by-product during the prepara-
tion of geranic acid from geranionitrile by the action of alcoholic
potash. Methyl hexylene carbinol, C,H,,OH, results, together
with geranic acid and methyl hexylene ketone, in the hydrolysis
of geranionitrile.

It should be especially noted that methyl heptenone, C,H,,O,
occurs, together with geraniol and geranial, in many ethereal
oils. Its constitution has been explained by Tiemann and
Semmler’s' investigations, according to which the ketone is
almost quantitatively converted into acetone and _ laevulinic
acid by successive oxidation with potassium permanganate and
chromic acid.

When geranial is carefully oxidized with chromic anhy-
dride, an uncrystallizable acid, C,H,,(OH),COOH, is obtained
which gives methyl hexylene ketone on distillation (Tiemann
and Semmler). According to Barbier and Bouveault,? when
geranial is oxidized with sodium dichromate and sulphuric
acid at a low temperature, it yields formic acid, acetic acid,
and a methyl heptenoncarboxylic acid; this acid is probably
identical with the acid, C,H,,(OH),COOH, obtained by Tie-
mann and Semmler. By more vigorous oxidation with boil-
ing chromic acid mixture, geranial is converted into carbon
dioxide, formic acid, acetic acid and terebic acid (Barbier and
Bouveault).

In this connection it should be mentioned that some of the
derivatives of geranial described in the preceding were prepared
by different chemists before Tiemann and Semmler obtained
them, but such compounds were generally designated by different
names. Thus, Barbier® first prepared geranialoxime, and con-
verted it into geranionitrile and then into geranic acid. Geranic
acid was previously described by Eckart* under the name “ rho-
dinolic acid.”

From the results of their experiments, Tiemann and Semmler’

1Tiemann and Semmler, Ber., 28, 2126.

Barbier and Bouveault, Compt. rend., 118, 1050; 122, 393.
3Barbier, Compt. rend., 116, 883.

4Eckart, Arch. Pharm., 229, 355.

="

SS ——

a-IONONE. 407

regard the following formulas as expressing the true constitution
of geranial and its derivatives :

i i a Ta =CH—CHO,
CH; H,
Geranial (citral) (dimethyl-2, 6-octadiéne-2, 6-al-8).
CH,;—C—=CH—CH,—CH,—C=—CH—COO0OH

CH, H,
Geranic acid (dimethyl-2, 6-octadiéne-2, 6-acid-8).

CHy—(=CH—CH,—CH,—CO—CH,

CH;
Methyl hexylene ketone (methyl-2-heptene-2-on-6).

It should further be mentioned that geranial undergoes con-
densation with acetone, yielding a ketone, pseudoionone,' C,,H,,O ;
its constitution is represented by the formula,

CH, Oe Bie Wii agama
CH, H,

Pseudoionone, C,,H,,O, boils at 143° to 145° under a pressure of
12 mm., has the specific gravity 0.9044, and the refractive power,
Ny = 1.5275.

When it is boiled with dilute sulphuric acid and a little
glycerol, it is converted into a mixture of two isomeric, cyclic
ketones, a- and f-ionone. This mixture was at first thought to be
an individual chemical compound and was called tonone,' C,,H,,O.
It boils at 126° to 128° (12 mm.), has the sp. gr. 0.9351 and the
- refractive index, pp, = 1.507, at 20°.

a-Ionone,* C,,H,,O, is prepared from a mixture of the a- and
8-ionones (“commercial ionone”) by conversion into its oxime,
crystallizing this compound from petroleum, and regenerating the
ketone with dilute sulphuric acid. It boils at 123° to 124° (11
mm.) or 134° to 136° (17 mm.), has the sp. gr. 0.932 and the
refractive index, np = 1.4980. Its owime crystallizes from petro-
leum and melts at 89° to 90°, while the oxime of f-ionone is a
liquid, hence a separation of the two ketones is rendered possible.
The semicarbazone dissolves more readily than the f-derivative in
petroleum, and melts at 107° to 108°. Other characteristic de-
rivatives have been prepared.

1Tiemann and Kriiger, Ber., 26, 3691.
2Tiemann, Ber., 31, 808 and 867; 33, 3704 and 3726; compare Lemme,
Chem. Centrl., 1900 [1.], 576.

408 THE TERPENES.

f-Ionone, C,,H,,O, is obtained from the mixture of the isomeric
ketones by means of its semicarbazone, which crystallizes more
readily than the corresponding a-derivative. The ketone boils at
127° to 128.5° (10 mm.) or 140° (18 mm.), has the sp. gr. 0.946
and the refractive index, ny = 1.521. Its ovime is an oil, and its
semicarbazone melts at 148° to 149°.

Oxidation with permanganate converts a-ionone into isogeronic
acid, C,H,,O,, and oxidation products of the latter, while S-ionone
gives rise to geronic acid and its oxidation products. The con-
stitutional formulas of the two ketones are :

CH, CH, CH, CH,
Ke i oC
. H,C C—CH=CH—CO—CH,
| | \CH=CH—Co—CH, feu
H,C: .C—CH, H,C_ C—CH,

\ZF SZ

Cv UH,

Na

a-Ionone. B-lonone.

Commercial ionone has the characteristic odor of violets, and
for this reason it is of considerable practical importance.’

Irone,’ C,,H,,O, is a structural isomeride of ionone, and is the
fragrant constituent of violets. It is an oil which is readily solu-
ble in alcohol, boils at 144° (16 mm.), has the sp. gr. 0.939 and
refractive index, np = 1.50113, at 20°; it is dextrorotatory.

Since it is impracticable to introduce into this book the results
of many investigations on geranial, reference may be made to the
following publications : ,

Bouveault, Bull. Soc. Chim., 27 [III.], 419 and 423.

Barbier, Bull. Soc. Chim., 27 [III.], 635.

Corie, C. and D., 54, 650.

Doebner, Ber., 37, 3195.

Flatau, Bull. Soc. Chim., 21 [IITI.], 158.

Flatau and Labbé, Bull. Soc. Chim., 79 [III.], 1012.

Ipatieff, Ber., 34, 594.

Labbé, Bull. Soc. Chim., 27 [III.], 77, 407 and 1026.

Semmler, Ber., 31, 3001.

Stiehl, Journ. pr. Chem., 58, 51.

1Tiemann and Kriiger, Ber., 26, 2675; 28, 1754; Barbier and Bouveault,
Bull. Soe. Chim., 15 [III.], 1002; Tiemann, Ber., 31, 808, 867, 1736, 2313,
and 3324; 32, 115; 33, 877, 3704 and 3726; Ziegler, Journ. pr. Chem., 57
{11.], 493.

CITRONELIAL. 409

Tiemann, Ber., $1, 2313, 3278, 3297 and 3324; 32, 107, 250,
812, 827 and 830.

Verley, Bull. Soc. Chim., 27 [III.], 408, 413 and 414.

Ziegler, Journ. pr. Chem., 57 [II.], 493.

2, MENTHOCITRONELLAL, C,,H,,0.

This aldehyde,’ previously termed menthony] aldehyde, results
on the oxidation of menthocitronellol (menthonyl alcohol) with
chromic acid. It has an odor like that of sweet orange, boils at 86°
to 88° (16 mm.), and at about 200° under atmospheric pressure ;
it has the specific gravity 0.8455 and the refractive index, np =
1.43903, at 20°.

Menthocitronellal-8-naphthocinchonic acid is formed by the con-
densation of the aldehyde with 8-naphthylamine and pyroracemic
acid; it melts at 214° to 215° (the corresponding derivative of
natural citronellal melts at 225°).

Menthocitronellal semicarbazone melts at 89°, and is optically
inactive.

3. OITRONELLAL, C,,H,,0.

This compound was formerly called “ citronellone”’ ; it has, how-
ever, been characterized as an aldehyde, and, in order to indicate
the aldehydic nature, is now termed citronellal. It derives its
name from its occurrence in oil of citronella (from Andropogon
nardus) ; this oil has been carefully studied by Gladstone,’ Wright,’
Kremers,‘ and Dodge.° It has been found by Schimmel & Co. in
the oils of Eucalyptus maculata and Eucalyptus maculata var.
citriodora, and, according to Débner, it also accompanies geranial
in the oil of lemon.

In order to prepare citronellal from citronella oil or eucalyptus
oil, the ethereal oil is shaken with a solution of acid sodium sul-
phite, and the resulting crystalline, additive compound is decom-
posed with sodium carbonate; pure citronellic aldehyde is then
obtained by distilling the reaction-product in a current of steam.
The citronellal so obtained from the ethereal oils is dextrorotatory ;
it is possible, however, that the specimens of citronellal having low
rotatory powers will prove to be mixtures of the two optically
active modifications.

1Wallach, Ann. Chem., 278, 313; 296, 120.

2Gladstone, Journ. Chem. Soc., 1872, 7.

3Wright, Journ. Chem. Soc., 1875, 1.

4Kremers, Proc. Amer. Pharm. Assoc., 1887; Amer. Chem. Journ., 14,
203; Ber., 25, 644, Ref.

5Dodge, Amer. Chem. Journ., 11, 456; 12, 553; Ber., 23, 175, Ref.; 24,
90, Ref.

410 THE TERPENES.

Citronellal may also be prepared by the oxidation of citronellol
with chromic acid ; the yield, however, issmall. By means of this
method a levo-citronellal may be obtained from the 1-citronellol of
rose oil.

Citronellal is a colorless liquid, boils at 205° to 208° at ordi-
nary pressure, and at 103° to 105° under a pressure of 15 mm.;
the specific gravity is 0.8538 at 17.5°, and the refractive index,
np = 1.4481. Its optical rotation was found by Kremers to be
[2]>=+ 8.18°, and by Tiemann and Schmidt,’ [a], = +
12°30’.

Pure citronellal is very unstable; when allowed to stand for
several months, it is almost entirely converted into isopulegol ;?
the same isomeric change is effected much more rapidly by the
action of acids.* When citronellal is treated with alkalis, it is
completely resinified.

When it is reduced in alcoholic solution with aT O acetic acid
and sodium amalgam, it yields citronellol, C,,H,,OH (Dodge,
Tiemann and Schmidt).

On oxidizing citronellal with silver oxide, citronellic acid,
C,,H,,0,, is obtained (Semmler), Oxidation with potassium per-
manganate, followed by chromic and sulphuric acids, converts
citronellal, like citronellol and citronellic acid, into acetone and
f-methyl] adipic acid. The aldehyde is, therefore, to be regarded
as dimethyl-2, 6-octene-2-al-8 (Tiemann and Schmidt):

CH,— —CH—CH 2—CH, UM ia lore 2—CHO.
H,; CH,

It unites with two atoms of bromine, forming a liquid additive
product (Dodge, Semmler).

According to Barbier,‘ menthoglycol, C,,H,,(OH),, is formed by
agitating citronellal with dilute sulphuric acid.

The normal addition-product of citronellal and sodium bisul-
phite,’ C,,H,,O-NaHSO,, is a crystalline compound, and is formed
by shaking a cold solution of sodium bisulphite (free from sul-
phurous anhydride) with citronellal; it is soluble in water, but
may be precipitated by the addition of a saturated salt solution.
Sodium carbonate or hydroxide converts it into citronellal. A
mono- and dihydrosulphonic acid are also described.°

1Tiemann and Schmidt, Ber., 29, 905.

*Labbé, Bull. Soc. Chim., 21 [III.], 1023; compare Tiemann, Ber.,
82, 825.

’Tiemann and Schmidt, Ber., 29, 913; 30, 22.

Barbier and Leser, Compt. rend., 124, 1308.

5Tiemann, Ber., 31, 3297.

ff
i
e)

CITRONELLAL-f-NAPHTHOCINCHONIC ACID. 411

Citronellylidene cyanoacetic acid,’ C,,H,,(CN)-COOH, is formed
by shaking citronellal with an aqueous solution of cyanoacetic acid
and sodium hydroxide ; it crystallizes from benzene or alcohol,
and melts at 137° to 138°. Its sodium salt is sparingly soluble,
and is especially characteristic.

Citronellal dimethylacetal,’ C,,H,,(OCH,),, is obtained by treat-
ing citronellal with a one per cent. solution of hydrogen chloride
in methyl alcohol. It boils at 110° to 112° (12 to 13 mm.), and
has the specific gravity 0.885 at 11.5°.

Phosphoric anhydride converts citronellal into a mixture of a
terpene (b. p. 175° to 178°), and citronellal phosphoric acid; the
latter crystallizes from water in prisms, melting at 203°. Itisa
monobasic acid, forms crystalline salts, and has the formula

(Dodge) :

0
C,H,,CHZO0 SP=o.
H—O/7

Citronellal-§-naphthocinchonic acid,

N=C—C,H
CHK |

ae
OOH
was discovered by Doébner.

It is especially valuable for the characterization of this alde-
hyde, and is prepared by heating an alcoholic solution of an excess
of citronellal with the molecular proportions of pyroracemic acid
and #-naphthylamine, for three hours. On cooling, citronellal-/-
naphthocinchonic acid separates in crystals ; these are washed with
ether, and recrystallized from alcohol containing hydrochloric acid.
The resultant hydrochloride is dissolved in ammonium hydroxide,
and the pure acid is precipitated from the ammoniacal liquid by
acetic acid ; it is again crystallized from dilute alcohol, and forms
colorless needles, melting at 225°.

When heated above its melting point, this compound loses car-
bonic anhydride and yields citronellal-f-naphthyl quinoline; this
amine crystallizes from dilute alcohol or petroleum ether in bright
needles, which melt at 53°.

1Tiemann, Ber., $2, 824.
2Harries, Ber., 33, 857; 34, 1498 and 2981.

412 THE TERPENES.

Citronellaloxime,' C,,H,,NOH, was obtained by Kremers, and
subsequently by Semmler,’ by the action of hydroxylamine on an
alcoholic solution of citronellal. It is an oil, which boils at 135°
to 136° (14 mm.), has a specific gravity of 0.9055 and refractive
index, np, = 1.47638, at 20°.

Citronellonitrile,| C,H,.CN, results on boiling the oxime with
acetic anhydride. It boils at 94° under 14 mm. pressure, has the
specific gravity 0.8645 and the index of refraction, np = 1.4545,
at 20°; the molecular refraction is 47.43.

Citronellic acid, C,H,,COOH, was prepared by Dodge,’ Semm-
ler,> and Kremers* by the oxidation of citronellal with moist
silver oxide. It is more readily formed by the saponification of
the corresponding nitrile with alcoholic potash (Semmler’). It
boils at 143.5° (10 mm.) and at 257° under atmospheric pres-
sure; its specific gravity is 0.9308 and the refractive power,
ny = 1.4545, at 20°. The molecule of citronellic acid appears to
contain one double linkage.

Citronellic acid is further obtained from geranic acid,
C,H,,COOH, by reduction with sodium and amy] alcohol.°

A small amount of citronellal is formed by strongly heating a
mixture of calcium citronellate and formate.°

Citronellamide,’ C,H,,CONH,, is produced by boiling citronello-
nitrile with a fifteen per cent. alcoholic potash solution during five
or six hours. It crystallizes from petroleum ether in colorless
needles, melts at 81.5° to 82.5°, is sparingly soluble in water, but
dissolves readily in most organic solvents.

Dioxycitronellic acid, C,H,,(OH),COOH, is formed by oxidizing
citronellic acid with a very dilute solution of permanganate at 0°.
It is a viscous liquid, and appears not to yield a lactone. On
further oxidation with a chromic acid mixture, it yields -methyl
adipic acid, C,H,,O, (Semmler’s citronellapimelic’acid).

Citronellal semicarbazone,’ C,,H,, = N: NHCONH,, is obtained
by shaking an alcoholic solution of citronellal with a solution of
semicarbazide hydrochloride and sodium acetate; it crystallizes
from chloroform and ligroine in white leaflets, and melts at 84°.

1Semmler, Ber., 26, 2254; compare Tiemann and Kriiger, Ber., 29, 926;
Tiemann and Schmidt, Ber., 30, 33.

2Dodge, Amer. Chem. Journ., 11, 456; 12, 553.

3Semmler, Ber., 24, 208.

4Kremers, Amer. Chem. Journ., 14, 203.

5Semmler, Ber., 26, 2254; compare Tiemann and Schmidt, Ber., 30, 33;
Barbier and Bouveault, Compt. rend., 122, 673, 737, 795 and 842.

6Tiemann, Ber., 31, 2899.

7Tiemann and Schmidt, Ber., 30, 34; 31, 3307; compare Barbier and
Bouveault, Compt. rend., 122, 737.

OXYHYDROMENTHONYLAMINE. 413

C. AMINES.

1, MENTHONYLAMINE, C,,H,,NH,.

According to Wallach,’ menthonylamine, C,,H,,NH,, is formed,
together with oxyhydromenthonylamine, C,,H,(OH)NH,, by the
reduction of menthonitrile with sodium and alcohol. Thirty
grams of sodium are gradually added to the solution of fifty
. grams of the nitrile in two hundred and fifty grams of abso-
lute alcohol ; when the reaction is complete, the product is dis-
tilled in a current of steam, the distillate is treated with a solution
of thirty-five grams of oxalic acid, and the non-basic impurities
are removed from the oxalic acid solution by redistillation with
steam. On cooling, the sparingly soluble menthonylamine oxalate
crystallizes in leaflets, whilst the oxalate of the base, C,,H,,NO,
remains in solution.

Menthonylamine, obtained from its oxalate, boils without decom-
position at 207° to 208°; it resembles the isomeric menthylamine
in readily absorbing carbonic anhydride from the air. It has the
specific gravity 0.8075 at 20° (the sp. gr. of menthylamine is
0.8600), and the index of refraction, np = 1.4500. It is feebly
dextrorotatory.

Menthonylamine hydrochloride, C,,H,,NH,HCl, is a crystalline
salt, stable in the air, and forms a sparingly soluble platinochloride.

The acid oxalate is slightly soluble in water, and separates from
it with one-half molecule of water of crystallization.

Acetyl menthonylamine is a liquid.

The oxamide,

ehsalgie

ONHC,,Hy»

is very soluble in alcohol, and melts at 82° to 83°.’

Menthocitronellol (menthonyl alcohol) and a hydrocarbon,
C,,H,,, are produced on treating menthonylamine oxalate with
sodium nitrite.

Oxyhydromenthonylamine, C,,H,(OH)NH,, boils at 252° to
255°, and forms very soluble salts. On treatment with nitrous
acid, this amine yields dimethyloctylene glycol (2, 6-dimethyloc-
tane-2, 8-diol), C,,H,,(OH),’; it is non-volatile with steam, and
boils at 153° to 156° under 19 mm. pressure.

1Wallach, Ann. Chem., 278, 313; 296, 120.

SESQUITERPENES AND POLYTERPENES.

SESQUITERPENES, C,,H,, AND SESQUITERPENE
ALCOHOLS, C,,H,,OH.

1, CADINENE, C,,H,,.

Cadinene resembles limonene in its behavior and in its distribu-
tion in ethereal oils. Like limonene it yields solid additive prod-
ucts with two molecules of halogen hydrides, but these compounds
are optically active, and, by elimination of the hydrogen chloride,
etc., may be reverted into optically active cadinene.

Although cadinene has been recognized in many ethereal oils, it
is, nevertheless, doubtful whether this hydrocarbon is actually the
most widely distributed of the sesquiterpenes, since reactions by
which cadinene can be definitely identified are, as a rule, unknown
for the other sesquiterpenes.

The name cadinene was introduced by Wallach’ owing to the oc-
currence of this sesquiterpene in large quantities in the oil of cade
(Oleum cadinum). This oil is the most convenient and cheap-
est source for its preparation. The investigations of Wallach,’
Schmidt,® Oglialoro,* Soubeiran and Capitaine® have shown that
cadinene occurs in the oil of cubeb. Wallach? also proved that it
occurs in patchouly oil, galbanum oil and oil of savin; Wallach
and Rheindorf® subsequently discovered it in the oil of paracoto
bark, and Wallach and Walker’ detected it as a constituent of oil
of olibanum. Bertram and Gildemeister* found cadinene in the
oil of betel leaves and in camphor oil; Bertram and Walbaum’®
recognized it in pine needle oil from Picea excelsa and Pinus
montana, and in the German oil of Pinus silvestris. Schimmel &

1Wallach, Ann. Chem., 271, 297; compare Troeger and Feldmann, Arch.
Pharm., 236, 692.

2Wallach, Ann. Chem., 238, 78.

3Schmidt, Arch. Pharm. [2], 141, 1.

4Oglialoro, Gazz. Chim., 5, 467.

sSoubeiran and Capitaine, Journ. Pharm., 26, 75; Pharm. Centr., 1840,
177.

6Wallach and Rheindorf, Ann. Chem., 271, 303.

*Wallach and Walker, Ann. Chem., 271, 295.

8Bertram and Gildemeister, Journ. pr. Chem., N.F., 39, 349.
9Bertram and Walbaum, Arch. Pharm., 231, 290.

414

CADINENE. 415

Co. obtained it from oil of cedar wood, Florida oil of pepper,
and oil of juniper. The same sesquiterpene is also found, ac-
cording to Semmler,' in oil of asafetida, and, according to Rey-
chler,? in oil of ylang-ylang. It also occurs in the oils of elder-
berry, wormwood, goldenrod, peppermint and angostura bark.

PREPARATION.—Pure cadinene is prepared from pure cadinene
dihydrochloride, obtained from the fractions boiling at 260° to
280° of the above-mentioned oils; the fraction obtained from
Olewm cadinum is best. The hydrogen chloride is removed from
the dihydrochloride by boiling with twice its weight of aniline, or
by heating with sodium acetate. In the latter method, the fol-
lowing process is employed.

Twenty grams of cadinene dihydrochloride and twenty grams
of anhydrous sodium acetate are covered with eighty cc. of glacial
acetic acid, and heated in a flask fitted with a reflux condenser.
At first the solids are dissolved, but very soon sodium chloride is
thrown out and the reaction is complete in about half an hour.
The product is diluted with water, the resultant hydrocarbon is
washed with sodium hydroxide, distilled in a current of steam
and rectified (Wallach *).

PROPERTIES.*—Cadinene boils at 274° to 275°, has the specific
gravity 0.9180 at 20° and 0.9210 at 16°; the refractive power
is 1.50647. Wallach and Conrady found the specific rotatory
power, [a],=— — 98.56°. It shows a very great tendency to
decompose into resinous substances on exposure to the air. It is
sparingly soluble in alcohol and glacial acetic acid, readily in
ether.

When cadinene is dissolved in chloroform and then shaken with
a few drops of concentrated sulphuric acid, the liquid assumes
an intensive green color, which passes into blue and is converted
into red by warming. The beautiful indigo-blue color is rendered
more apparent if the hydrocarbon be dissolved in an excess of
glacial acetic acid instead of chloroform, and then treated very
slowly with a little sulphuric acid. These color-reactions are
facilitated by allowing the cadinene to stand for some time in
the air.

On oxidation with chromic acid, this sesquiterpene yields the
lower fatty acids. If the hydrocarbon be added drop by drop to
fuming nitric acid, a violent reaction takes place and a yellow

1Semmler, Arch. Pharm., 229, 17.

2Reychler, Bull. Soc. Chim. [3], 11, 576; Ber., 28, 151, Ref.

8Wallach, Ann. Chem., 238, 80 and 84.

‘Wallach, Ann. Chem., 238, 80 and 84; compare Wallach and Conrady,
Ann. Chem., 252, 150; Wallach, Ann. Chem., 271, 297.

416 THE TERPENES.

compound is formed; this substance is quite insoluble in water,
soluble in sodium hydroxide, and appears to be amorphous.

Cadinene seems to be changed by continued heating with dilute
sulphuric acid (Wallach).

Cadinene dihydrochloride, C,,H,,:2HCl, was first obtained by
Soubeiran and Capitaine, subsequently by Schmidt, and Oglialoro,
from the oil of cubeb. According to Wallach,’ it is most con-
veniently prepared from Olewm cadinum. The fraction of the
latter oil boiling between 260° and 280° is diluted with twice its
volume of ether and saturated with hydrochloric acid gas; after
standing for a few days, a portion of the ether is distilled off, and
on further evaporation of the liquid the dihydrochloride crystal-
lizes. The crystals are filtered by the pump, washed with a little
alcohol, and recrystallized from ethyl acetate; the compound is
readily soluble in warm acetic ether, but difficultly in the cold
solvent. When crystallized slowly from ether, it separates in
hemihedral rhombic prisms, which show a close resemblance to
those of limonene tetrabromide (Hintze).

Cadinene dihydrochloride melts at 117° to 118°, and has the
specific rotatory power, [a] p = — 36.82° (Wallach and Conrady).

When it is heated with aniline or sodium acetate, it is decom-
posed into cadinene ; the resultant hydrocarbon may be readily
reconverted into pure cadinene dihydrochloride, having the same
rotatory power as the original dihydrochloride, by treatment with
a glacial acetic acid solution of hydrogen chloride.

A saturated hydrocarbon, C,,H,,, is formed when cadinene di-
hydrochloride is heated with hydriodic acid at 180° to 200°; it
boils at 257° to 260°, has the specific gravity 0.872 at 18°, and
the refractive power, np = 1.47439 (Wallach and Walker *).

Cadinene dihydrobromide, C,,H,,- 2HBr, is obtained by shaking
an acetic acid solution of pure cadinene with fuming hydrobromic
acid; it forms white needles resembling those of the dihydro-
chloride. It melts at 124° to 125°, is difficultly soluble in alco-
hol, but dissolves readily in ethyl acetate. The rotatory power is
[a] p= — 36.13° (Wallach).

Cadinene dihydriodide, C,,H,,-2HI, is prepared like the dihy-
drobromide. It crystallizes from petroleum ether in white, woolly
needles, and melts with decomposition at 105° to 106°. The
rotatory power is [a], = — 48.00°.

Cadinene nitrosochloride,* C,,H,,: NOCI, is obtained when a s0-

1Wallach, Ann. Chem., 238, 82; compare Cathelineau and Hauser, Bull.
Soc. Chim., 25 [III.], 247 and 931.

2Hintze, Ann. Chem., 238, 82.

3Wallach and Walker, Ann. Chem., 271, 295.
4Schreiner and Kremers, Pharm. Arch., 2, 273.

CARYOPHYLLENE DIHYDROCHLORIDE. 417

lution of cadinene in glacial acetic acid is well cooled with a freez-
ing mixture, ethyl nitrite is added, and the mixture is carefully
treated with a saturated solution of hydrogen chloride in glacial
acetic acid. It melts with decomposition at 93° to 94°.

Cadinene nitrosate,' C,,H,,-N,O,, is produced on treating a well
cooled mixture of a solution of the sesquiterpene in glacial acetic
acid, and ethyl nitrite, with strong nitric and glacial acetic acids ;
the reaction-mixture is diluted with alcohol, the nitrosate being
precipitated. The yield is over forty per cent. It melts and
decomposes at 105° to 110°.

2. CARYOPHYLLENE, C,,H,,.

Caryophyllene, which occurs in the oil of cloves and clove stems,
in copaiba balsam oil, and in the oil of Canella alba, was charac-
terized as a definite sesquiterpene by Wallach and. Walker’ by
means of its conversion into caryophyllene alcohol; it has not,
however, been prepared absolutely pure. When the elements of
water are eliminated from caryophyllene alcohol, it is not con-
verted into caryophyllene, but is changed into the isomeric sesqui-
terpene, clovene.

Impure caryophyllene, obtained by the fractional distillation of
the oil of cloves, boils at 258° to 260°, has a specific gravity
0.9085 at 15°, and the refractive power, np = 1.50094. It is
optically active (Wallach).

According to Schreiner and Kremers,*® a comparatively pure
specimen of caryophyllene boils at 136° to 137° under a pressure
of 20 mm., has the specific gravity 0.90301 and refractive index,
np = 1.49976, at 20°, and the specific rotatory power, [4])=
— 8.959° at 20°. The physical constants have also been deter-
mined by Erdmann,‘ and by Kremers.’

According to Wallach, caryophyllene combines with the halogen
hydrides, yielding liquid addition-products, while caryophyllene
alcohol (see below) forms solid derivatives when it is treated with
the phosphorus halides. These reactions, and the fact that it is
impossible to reconvert caryophyllene alcohol into caryophyllene,
indicate that the formation of this alcohol is preceded by a molec-
ular rearrangement.

Caryophyllene dihydrochloride, C,,H,,-2HCl.—According to Kre-
mers,* it appears that this compound may be obtained in a crys-

i1Schreiner and Kremers, Pharm. Arch., 2, 273.

2Wallach and Walker, Ann. Chem., 271, 285.

3Schreiner and Kremers, Pharm. Arch., 2, 282.

4Erdmann, Journ. pr. Chem., 56 [II.], 146.
5Kremers, Pharm. Arch., 1, 211.

27

418 THE TERPENES.

talline form by saturating an ethereal solution of the sesquiterpene
with hydrogen chloride, and exposing the solution to intense cold.
It melts at 69° to 70°.

When it is treated with glacial acetic acid and anhydrous
sodium acetate, it yields a sesquiterpene which is not regenerated
caryophyllene ; it,has a sp. gr. 0.9191 at 20°, n, = 1.49901, and
[a] >= — 35.39°; it is perhaps identical with clovene.

Caryophyllene bisnitrosochloride, (C,,H.,,),“N,O,Cl,, forms a white
powder, which is sparingly soluble and melts with decomposition
at 161° to 163°. The yield is small (Wallach).

According to more recent investigations, the bisnitrosochloride
may be obtained in a crystalline form, when a mixture of the ses-
quiterpene, alcohol, ethyl acetate and ethyl nitrite is well cooled
with a freezing mixture, and treated with a saturated, alcoholic
solution of hydrogen chloride; the reaction-mixture is allowed to
stand for one hour in the cold, and is then exposed to the sunlight.
It melts and decomposes at 158°, and has the bimolecular formula.
It reacts with benzylamine forming two derivatives, a- and f-ben-
zylnitrolamine; the a-compound melts at 167° and is sparingly
soluble in alcohol, while the $-modification melts at 128° and is
readily soluble (Schreiner and Kremers’).

Caryophyllene nitrosite,' C,,H.,,-N,O,, is formed by treating a mix-
ture of equal volumes of the sesquiterpene and petroleum ether
with a concentrated solution of sodium nitrite and glacial acetic
acid. It crystallizes in blue needles, melts at 107°, and dissolves
in alcohol forming a blue solution; the blue color of the crystals
may be removed by recrystallization. It has a specific rotatory
power, [a], = + 103°, in a1.6 per cent. benzene solution. Cry-
oscopic determinations in benzene solution indicate that this com-
pound has the simple molecular formula above indicated. When
this nitrosite is exposed to the sunlight in an absolute alcoholic
solution, it is converted into a colorless a-isomeride, having the
same molecular weight ; it melts at 113° to 114°, is optically in-
active, and is soluble in alcohol and benzene. When the nitro-
site is dissolved in benzene and is exposed to the sunlight, it is
transformed into a colorless f-isomeride ; this compound melts at
146° to 148°, and is insoluble. in benzene and alcohol.

The nitrosite reacts with benzylamine, forming a benzylnitrol-
amine (m. p. 167°).

Caryophyllene isonitrosite (bisnitrosite), (C,, H,,),; (N,O,), , results
on heating the alcoholic solution of the nitrosite ; it forms color-
less crystals, and melts at 53° to 56°.

Caryophyllene nitrosate, C,,.H,,-N,O,, is readily prepared by

1Schreiner and Kremers, Pharm. Arch., 1, 209; 2, 273.

CARYOPHYLLENE ALCOHOL. 419

adding a mixture of glacial acetic acid and concentrated nitric
acid to a well cooled mixture of ten cc. of the fraction of oil of
cloves containing caryophyllene, nine cc. of amyl nitrite and six-
teen cc. of glacial acetic acid; the separation of the crystalline
nitrosate is hastened by the addition of alcohol. It is insoluble
in alcohol and ether, sparingly soluble in glacial acetic acid, and
rather soluble in benzene and chloroform.; it crystallizes from ben-
zene in slender needles, and melts at 148° to 149° (Wallach and
Tuttle).

According to Kremers, this nitrosate is to be regarded as having
a bimolecular structure and should be termed caryophyllene bisnitro-
sate, (C,,H,,:N,O,),. It yields a benzylnitrolamine, melting at
128°.

When the nitrosate is boiled with alcoholic potash for a short
time, it yields a compound which crystallizes in white needles,
melting at 220° to 223°; it is possibly an oxime derivative of
caryophyllene.

Caryophyllene nitrolbenzylamines,

NO
CHK
NH - CH,C,H;.

The a- and #-modifications are obtained from the bisnitrosochlo-
ride and benzylamine ; the a- melts at 167°, and the f-nitrolamine
at 128°. The nitrolamine prepared from the nitrosate and benzyl-
amine is identical with the f-derivative and melts at 128°. The
compound produced from the nitrosite and benzylamine appears
to be identical with the a-nitrolamine and melts at 167°. The
a-compound is less soluble in alcohol than the $-modification.

_ Garyophyllene nitrolpiperidide,'

NO
Cr on,

results by treatment of the nitrosate with piperidine ; it separates
from alcohol in transparent crystals, melting at 141° to 148°.
Caryophyllene alcohol, C,,H,.OH, is obtained according to the
method of preparation of terpene alcohols proposed by Bertram,’
and modified for this substance by Wallach and Walker.
Twenty-five grams of the fraction of oil of cloves boiling at
250° to 260° are introduced into a mixture of one kilogram of

1Wallach and Tuttle, Ann. Chem., 279, 391; compare Kremers, Schreiner
and James, Pharm. Arch., 1, 209.
2Bertram, German Patent, No. 80,711.

420 THE TERPENES.

glacial acetic acid, twenty grams of concentrated sulphuric acid
and forty grams of water; the solution is heated for twelve hours
on the water-bath. As large a quantity of oil of cloves can be
subsequently added as the warm acid mixture is capable of dis-
solving. The dark colored reaction-product is distilled in a cur-
rent of steam. At first, acetic acid and a mobile oil pass over,
but towards the end of the operation caryophyllene alcohol col-
lects in the receiver, and gradually solidifies ; it is dried, and
then distilled from a retort.

Caryophyllene alcohol boils without decomposition at 287°
289°, sublimes in lustrous needles, and may be voorpoulinae
from alcohol, the melting point changing from 94° or 95° to 96°.
It is almost insoluble in cold, and only sparingly soluble in hot,
water, but dissolves freely in most of the ordinary organic sol-
vents. The crystalline alcohol is almost without odor, but its
vapors have a characteristic smell resembling that of pine needles.
It is optically inactive.

Caryophyllene phenylurethane, C,,H,.O:CO-NHC,H,, is pro-
duced by the action of carbanile on the aleohol. It crystallizes
from a mixture of alcohol and ether in needles, and melts at
136° to 137° (Wallach and Tuttle’).

Caryophyllene acetate, C,,H,OCOCH,, may be prepared by
heating the iodide, C,,H,,I, with sodium acetate and glacial acetic
acid. The product partially solidifies and is recrystallized from
methyl alcohol (Wallach and Tuttle’).

Caryophyllene chloride,’ C,,H,,Cl, is readily formed by treating
the theoretical quantity of phosphorus pentachloride with caryo-
phyllene alcohol, care being taken to exclude all moisture. After
removal of the phosphorus oxychloride formed during the reac-
tion, the product is washed with soda solution, and crystallized
from alcohol, ethyl acetate or ligroine. It separates in well
defined crystals, melts at 63°, and boils without decomposition at
293° to 294°.

Caryophyllene bromide,’ C,.H,.Br, results when the alcohol is
treated with phosphorus tribromide ; it separates from alcohol in
rhombic crystals, which melt at 61° to 62°.

Caryophyllene iodide, C,,H,.I, is prepared by adding a quantity
of iodine, sufficient for the formation of phosphorus triiodide, to a
solution of yellow phosphorus in carbon bisulphide, and treating
this solution with the theoretical amount of caryophyllene alcohol.
It crystallizes in long, colorless needles or rhombic prisms, and
melts at 61°.

1Wallach and Tuttle, Ann. Chem., 279, 391.
2Wallach and Walker, Ann. Chem., 271, 285.

HUMULENE. 421

A hydrocarbon, C,,H,,, is obtained when the above-mentioned
iodide is dissolved in ether and treated at the ordinary tempera-
ture with sodium in the form of wire. After repeated crystalli-
zation, first from ethyl acetate and then from alcohol, it forms
well defined, transparent prisms, and melts at 144° to 145°. It
is a saturated hydrocarbon, and is as stable towards oxidizing
agents as paraffin (Wallach and Tuttle).

Caryophyllene nitrate, C,,H,ONO,, is produced by dissolving
earyophyllene alcohol in a very small quantity of ethyl alcohol,
and gradually adding a large excess of fuming nitric acid to the
well cooled solution ; on keeping this mixture for several hours at
the ordinary temperature, the nitric acid ester is deposited in
splendid, colorless needles, which are filtered on glass wool. A
further quantity of this substance is precipitated, but in an impure
condition, by adding water to the acid mother-liquor; it is then
purified by distillation with steam. :

lt crystallizes in rhombic prisms, melts at 96°, and is more
sparingly soluble in alcohol, ether and benzene than caryophyllene
alcohol. It is saponified only with great difficulty.

Caryophyllene alcohol, its halogen derivatives, and the nitrate
are saturated compounds, and are extremely stable.

3. CLOVENE, C,H

15° 24°

When caryophyllene alcohol is treated with dehydrating agents,
it is converted into the hydrocarbon clovene, isomeric with caryo-
phyllene.

Ten grams of caryophyllene alcohol are heated for fifteen
minutes almost to its boiling point with excess of phosphoric anhy-
dride, and, after cooling, the resultant hydrocarbon is distilled
over in a current of steam. The oil is again treated with phos-
phoric anhydride as before, the product distilled with steam and
rectified (Wallach and Walker’).

Clovene boils at 261° to 263°, has a specific gravity of 0.930
and refractive power, np = 1.50066, at 18°. It cannot be con-
verted into caryophyllene alcohol from which it is derived, hence
it must be different from caryophyllene. It does not yield a
nitrosochloride, and apparently has only one ethylene linkage.

4, HUMULENE, C,,H,,.

The ethereal oil of hops contains a terpene, C,,H,,, which pos-
sibly belongs to the series of olefinic terpenes, a hydrocarbon,
C,,H,,, an oxidized compound which resembles geraniol, and, as

1Wallach and Walker, Ann. Chem., 271, 294 and 298.

422 THE TERPENES.

the chief constituent, a sesquiterpene which boils at 166° to 171°
under a pressureof 60 mm.; this sesquiterpene is called humulene
(Chapman’).

Humulene boils at 263° to 266° at ordinary pressure, and at
166° to 171° under 60 mm. pressure ; it has a specific gravity of
0.9001 at 20°. It forms a liquid tetrabromide and a liquid dihy-
drochloride, and does not yield an alcohol when boiled in glacial
acetic acid solution with dilute sulphuric acid.

Humulene nitrosochloride, C,,H,,* NOCI, is a white, crystalline
substance, which melts and decomposes at 164° to 165°.

Humulene nitrosate, C,,H,,: N,O,, melts at 162° to 163°.

Humulene nitrolpiperidide,

NO
Cr cH,

crystallizes from alcohol in small, white, glistening plates, and
melts at 153°. Its hydrochloride crystallizes from boiling water
in hard, nodular masses ; the platinochloride separates from alco-
hol in reddish needles, and melts with decomposition at 187° to
189°.

Humulene nitrolbenzylamine,

NO

C, 5H,
nf wn - CH, C,H,

crystallizes from boiling alcohol and melts at 136°. Its hydro-
chloride is formed by passing hydrogen chloride into the dry
ethereal solution of the base, and melts with some decomposition
at 187° to 189°.

Humulene nitrosite, C,,H,,:N,O,— Nitrous acid reacts with
humulene forming two compounds, one of which is probably a
true nitroso-, the other an isonitroso- or bisnitroso-derivative. The
nitroso-compound crystallizes from alcohol in magnificent, blue
needles, and melts at 120°. The isonitroso-compound is formed
in small quantity together with the nitroso-derivative; it sepa-
rates from alcoholic solutions in colorless crystals, and melts at
165° to 168°. When the blue nitroso-derivative is crystallized
several times from alcohol, it is completely converted into the
colorless isonitroso-derivative.

It should also be noted that humulene occurs in the oil of pop-
lar buds. According to Fichter and Katz,’ the principal fraction

1Chapman, Journ. Chem. Soc., 1895 (1), 54 and 780; Ber., 28, 303 and
920, Ref.; compare Kremers, Pharm. Arch., 1, 209.
2¥Wichter and Katz, Ber., 32, 3183.

ci tare = ld

CEDRENE AND CEDROL. 423

obtained from this oil boils at 182° to 137° (13 mm.), and at
263° to 269° at ordinary pressure. It has the sp. gr. 0.8926 at
15°/4°, and a specific rotatory power, [a], = 10°48’ at 22°; its
vapor density corresponds with that of a compound, C,,H,,. It
yields a nitrosochloride, C,,H,,* NOCI, melting at 164° to 170°,
from which a nitrolpiperidide (m. p. 151° to 152°) and a nitrol-
benzylamine (m. p. 132° to 133°) are obtained. The nitrosite
forms blue needles (m. p. 127°), but on recrystallization from
alcohol, it becomes colorless and melts at 172°. The nitrosate
melts at 162° to 163°. It will be observed that the properties
of this sesquiterpene from the oil of poplar buds and of its deriva-
tives resemble those of humulene from oil of hops in all respects
except the optical rotation ; the humulene in oil of hops is optic-
ally inactive, while that in the oil of poplar buds is active.

5. CEDRENE, C,,H,,, AND CEDROL (“CEDAR CAMPHOR’ s
C,,H,,OH.

The ethereal oil of cedar wood consists almost entirely of a
liquid sesquiterpene, C,,H.,,, and a solid compound, C,,H,,OH, hav-
ing the properties of a tertiary alcohol ; the sesquiterpene has not
been identified with any of the other known members of this
class, and is called cedrene (Wallach ’).

When rectified by distillation over sodium, cedrene is obtained
as a viscous, colorless liquid, boiling at 131° to 132° (10 mm.),
and at 262° to 263° under atmospheric pressure. It is levorota-
tory, [4]> = — 47° 54’ (Rousset ’).

Cedrene unites with bromine and the halogen hydrides, forming
very unstable, liquid addition-products.

- On oxidation with an excess of chromic acid in a sulphuric
acid solution, cedrene yields an acid, C,,H,,O,, which boils at
220° to 230° (9 mm.).

Cedrene is not converted into an alcohol, C,,H,,OH, on treat-
ment with glacial acetic and sulphuric acids.

The solid compound, C,,H,,OH, occurring with cedrene in cedar
wood oil, is termed cedrol or “cedar camphor.” It forms a lus-
trous, crystalline mass, melts at 74° and boils at 282° (Walter *).
It crystallizes from dilute methyl] alcohol in colorless needles, and,
after repeated crystallizations, it softens at about 78°, and melts
at 85° to 86°. It is optically active. |

1Wallach, Ann. Chem., 271, 299.

2Rousset, Bull. Soc. Chim., 17 [III.], 4865.

8Walter, Ann. Chem., 39, 247; 48, 35.

4Schimmel & Co., Semi-Annual Report, Oct., 1897, 14; compare Rousset,
Bull. Soc. Chim., 17 [III.], 485; Chapman and Burgess, Chem. News, 74, 95.

424 THE TERPENES.

Walter observed that, when “cedar camphor” is heated with
phosphoric anhydride, it is decomposed into water and a sesqui-
terpene, C,,H,,, which he called cedrene. Rousset reports that
cedrol is dehydrated with formation of a sesquiterpene by the
action of benzoyl chloride, and by chromic acid, and partially by
acetic anhydride ; however, on heating with the latter reagent at
100°, a part of the cedrol is converted into an acetate, C,,H,.O :-
COCH,, which boils at 157° to 160° (8 mm.).

According to Schimmel & Co., water is very readily eliminated
from cedrol by the action of concentrated formic acid at the ordi-
nary temperature ; the hydrocarbon, C,,H,,, thus obtained boils at
262° to 263°, and is levorotatory, [a], = — 80°. It appears
to be identical with the cedrene occurring in cedar wood oil.

Cedrol reacts like a tertiary alcohol since it does not give rise to
an aldehyde or ketone on oxidation.

Cedrone, C,,H.,,O, is a ketone which is formed on the oxidation
of natural cedrene with an acetic acid solution of chromic anhy-
dride ; it boils at 147° to 151° (7.5 mm.), does not form a erys-
talline derivative with sodium bisulphite, but yields iodoform on
treatment with sodium hypobromite and potassium iodide. Its
oxime boils at 175° to 180° (8 mm.), and is converted into an
acetate (b. p. 185° to 190° at 9 mm.) by acetic anhydride.

Isocedrol, C,,H,,OH, results on reducing cedrone in an ethereal
solution with sodium. This alcohol, isomeric with “ cedar cam-
phor,” boils at 148° to 151° (7 mm.), and yields a benzoate, boil-
ing at 221° to 223° under 6 mm. pressure.

6. CUBEB CAMPHOR, C,,H,,.OH.

The oil of cubeb, prepared from old cubebs, contains the sesquiter-
pene cadinene, and a sesquiterpene alcohol, C,,H,,OH; this alcohol
has been the subject of investigations by Blanchet and Sell,’ Wink-
ler,? Schaer and Wyss,* and Schmidt.‘ Cubeb camphor separates
from a mixture of ether and alcohol in large, odorless, rhombic erys-
tals, melts at 65°, and boils at 248° with the elimination of a small
quantity of water. It is optically levorotatory. It loses water
when it is heated at 200° to 250° or allowed to remain in a desic-
cator over sulphuric acid; the nature of the resultant sesquiter-
pene, cubebene has not been explained.

1Blanchet and Sell, Ann. Chem., 6, 294.

2Winkler, Ann. Chem., 8, 203.

3Schaer and Wyss, Jahresb. Chem., 1875, 497.
4Schmidt, Zeitschr. fiir Chem., 1870, 190; Ber., 10, 189.

We ed

ae

PATCHOULY ALCOHOL AND PATCHOULENE. 425

7. LEDUM CAMPHOR, C,,H,,OH, AND LEDENE, C,,H,,.

Ledum camphor’ occurs in the oil of Labrador tea, obtained
from the leaves of Ledwm palustre. When purified by recrys-
tallization from alcohol, it melts at 104° to 105°, and boils at
282° to 283°. It sublimes’ in long, white needles, and its
solution in alcohol is feebly dextrorotatory, [a],= + 7.98°. It
is a powerful poison, affecting the central nervous system.

Ledum camphor readily loses water by warming with acetic
anhydride or dilute sulphuric acid and yields ledene, C,,H,,, which
is an oil boiling at 255°.

The chloride, C,,H,,Cl, is obtained as a yellowish oil by the
careful action of phosphorus pentachloride on a solution of the
camphor in petroleum ether.

Ledum camphor must be considered as a tertiary sesquiterpene
alcohol, since it is not attacked by potassium permanganate

(Hjelt ’).

24?

8, PATCHOULY ALCOHOL, C,,H,OH, AND PATCHOULENE,
Se BS

The oil of patchouly contains liquid substances, together with a
solid compound which was investigated by Gal,*® and Montgolfier,*
and named “patchouly camphor.” More recently, Wallach and
Tuttle® recognized the alcoholic nature of this compound and
called it patchouly alcohol. It forms hexagonal prisms, melting
at 56°, boils at 206°, and is optically levorotatory.

Tt has long been known that patchouly alcohol can be decom-
posed by the action of acetic anhydride into water and a sesqui-
terpene, C,,H,,. According to Wallach and Tuttle, the same
hydrocarbon, patchoulene, i is obtained by the action of feeble de-
hydrating agents on the alcohol. The best method for preparing
this sesquiterpene is by heating patchouly alcohol with acid
potassium sulphate at 180°, for one and one-half hours.

Patchoulene boils at 254° to 256°, has the specific gravity of
0.939 at 23°, and the index of refraction, n, = 1.50094. It has
an odor recalling that of cedrene, and reel contains one
ethylene linkage.

1Rizza, Journ. Russ. Chem. Soc., 19, 319; Iwanow, Jahresb. Chem., 1879,
909; Trapp, Ber., 8, 542; Hjelt and Collan, Ber., 15, 2501; Hjelt, Ber.,
28, 3087.

2Hjelt, Ber., 28, 3087.

5Gal, Zeitschr. fiir Chem., 1869, 220.

4Montgolfier, Bull. Soc. Chim., 28, 414.
5Wallach and Tuttle, Ann. Chem., 279, 394.

426 THE TERPENES.

9. GUAIOL, C,.H,.OH.

15°25

The sesquiterpene alcohol obtained by Schimmel & Co." from
the oil of guaiac wood is identical with a product subsequently
obtained from the so-called Champaca wood oil by distillation with
steam. This compound, which is called guaiol or champacol
according to its source, has been investigated by Wallach and
Tuttle.”

Guaiol is purified by distillation in vacuum, and then washing
with ether. It boils at 155° to 165° under a pressure of 13 mm.
When recrystallized several times from alcohol, it forms lustrous,
transparent prisms, which melt at 91°, boil at 288°, and are
levorotatory.

The brilliant colors which are formed by the action of dehy-
drating agents on guaiol are especially characteristic. When
heated with zinc chloride at 180° and then distilled with steam,
a blue oil is obtained. This is a sesquiterpene, and boils at 124°
to 132° under 13 mm. pressure; its specific gravity at 20° is 0.910
and the refractive index, n, = 1.50114. The blue color of this
hydrocarbon is due to impurities consisting of oxidation products
of the sesquiterpene (Wallach and Tuttle).

According to Schimmel & Co., acetic anhydride reacts with
guaiol forming a liquid acetate, which boils at 155° under a pres-
sure of 10 mm.

10. SANTALOL, C,,H,,OH, AND SANTALENE, C,,H,,.

15-25

East Indian sandalwood oil consists chiefly of a mixture of two
sesquiterpene alcohols, C,,H,,OH, which are called a- and f-san-
talol ; the two isomeric santalenes also occur in the oil, together
with other compounds. A mixture of the two alcohols is fre-
quently called “ santalol,’”’ and is known commercially as “ gonorol.”

a-Santalol,® C,,H,.OH, is a colorless, oily liquid, having a faint
odor ; it boils at 300° to 301°, has the sp. gr. 0.9854 at 0°, and
the specific rotatory power, [4], = —1.2°. Its acetate boils at
308° to 310°.

f-Santalol, C,,H,.OH, resembles its isomeride, boils at 309° to
310°, has the sp. gr. 0.9868 at 0°, and [a],>=— 56°. Its
acetate boils at 316° to 317°.

These alcohols are probably primary alcohols, and, when treated

1 Schimmel & Co., Semi-Annual Report, April, 1892, 42; April, 1893, 33.

2 Wallach and Tuttle, Ann. Chem., 279, 394.

3Guerbet, Compt. rend., 130, 417 and 1324; Soden and Miiller, Pharm.

Zeit., 44, 258; compare Parry, C. and D., 53, 708; 55, 1023; Schimmel &
Co., Semi-Annual Report, April, 1899, 38 and 40; April, 1900, 42 and 48.

’
|
>
7,
a
.

SANTALIC ACID. 427

with dehydrating agents, are converted into two isomeric sesqui-
terpenes, a- and {-isosantalene, C,,H,,. These compounds are
colorless liquids, having an odor of turpentine; the a-isosantalene
boils at 255° to 256°, and has [a], = + 0.2°, while the -deriv-
ative boils at 259° to 260°, and has [a], = + 6.1°.

_ a-Santalene, C,,H,,, boils at 252° to 252.5°, has the sp. gr.
0.9134 at 0°, and [a],— — 13.98°. When heated in a closed
tube with glacial acetic acid at 180° to 190°, it forms an acetate,
C,,H,, ‘ C,H,O,, boiling at 164° to 165° (14 mm.). When dis-
solved in ether and treated with dry hydrogen chloride, it forms
a dihydrochloride, C,,H,,* 2HCl, which decomposes on distillation
in vacuum ; its specific rotatory power is [a], = + 6°.

a-Santalene forms a nitrosochloride, C,,H,,* NOCI, which crys-
tallizes from benzene in prisms, and melts and decomposes at
122°; the nitrolpiperidide crystallizes from alcohol in needles, and
melts at 108° to 109°.

f-Santalene, C,,H,,, boils at 261° to 262°, has the sp. gr.
0.9139 at 0°, and the rotatory power, [a])—= — 28.55°. Its
acetate, C,,H,,* C,H,O,, boilsat 167° to 168° (14 mm.); its dihy-
drochloride, C,,H,,* 2HCl, is decomposed on distillation, and has
the rotatory power [a], = + 8°.

B-Santalene yields a mixture of two nitrosochlorides, C,,H,, °-
NOCI, on heating its solution in petroleum ether with nitrosyl
chloride; they are separated by fractional crystallization from
alcohol. The less soluble derivative melts at 152°, and the other,
which is formed in larger quantities, melts at 106°; the cor-
responding nitrolpiperidides melt at 101°, and 104° to 105°,
respectively.

According to Soden and Miiller, when santalene (f-santalene)
is treated with glacial acetic and sulphuric acids by Bertram’s
method, it yields a sesquiterpene alcohol, C,,H,,OH, which has a
strong odor of cedar ; it boils at 160° to 165° (6 mm.), and has
the sp. gr. 0.9780 at 15°.

In addition to the santalols and santalenes, East Indian sandal-
wood oil contains the following compounds (Guerbet’).

Santalal, C,,H,,O.—This substance has the properties of an
aldehyde, and boils at 180° (14 mm.); it is a colorless, oily
liquid, having a strong odor of peppermint. It yields a semicar-
bazone, which crystallizes in small needles, and melts at 212°.

Santalic acid, C,,H,,O,, is a liquid, boiling at 210° to 212°
under 20 mm. pressure.

1Guerbet, Compt. rend., 130, 417; compare Chapoteant, Bull. Soc. Chim.,
$7 [II.], 303; Chapman and Burgess, Proc. Chem. Soc., 1896, 140; Chap-
man, Journ. Chem. Soc., 79, 134.

428 THE TERPENES.

Teresantalic acid, C,,H,,O,, crystallizes from alcohol in prisms,
melting at 157°.

When West Indian sandalwood oil is saponified with alcoholic
potash, and fractionally distilled in a vacuum, a sesquiterpene alco-
hol, amyrol, C,,H,,OH, is obtained. It isa colorless, viscous liquid,
having a faint odor and bitter taste; it boils at 299° to 301°
(748 mm.) and at 151° to 152° (11 mm.). Its sp. gr. is 0.981
at 15°, and [a],= + 27°. When heated with phthalic anhy-
dride at 110°, it loses water and yields a sesquiterpene.’ It is
possible that amyrol, like santalol, may consist of two similar
alcohols, having different rotatory powers.

In a more recent publication, Soden? states that a-santalol is
probably a sesquiterpene alcohol having the formula, C,,H,,OH,
and not C,,H,,OH ; it forms the chief constituent of ‘ santalol ”
and East Indian sandalwood oil. #-Santalol may also have the
formula C,,H,,OH.

11. GALIPOL, C,,H,,OH, AND GALIPENE, C,,H,,.

According to investigations by Beckurts and Troeger,® the
oil of angostura bark contains about fourteen per cent. of a sesqui-
terpene alcohol, C,,H,OH, called galipol. It boils at 264° to
265°, has the specific gravity 0.9270 at 20°, and is optically in-
active ; its refractive index is n, = 1.50624.

The sesquiterpene, C,,H,,, galipene, is also contained in angos-
tura bark oil ; it is further obtained by treating galipol with phos-
phoric anhydride. It boils at 255° to 260°, has the specific grav-
ity 0.912 at 19°, and is optically inactive. It yields a liquid,
unstable additive product with hydrogen bromide.

12, CAPARRAPIOL, C,,H,,OH, AND CAPARRAPENE, C,,H,,.

The acid-free oil obtained from the essential oil of caparrapi con-
tains a sesquiterpene alcohol, caparrapiol,* which boils at 260°
(757 mm.); it has the specific gravity 0.9146, the refractive index,
n, = 1.4848, and the rotatory power, [a], = — 18.58°. When
distilled with phosphoric or acetic anhydride, it is converted into
the sesquiterpene, caparrapene. This sesquiterpene is a colorless
liquid, which boils at 240° to 250°, has the sp. gr. 0.9019 at 16°,

1Soden, Pharm. Zeit., 45, 229 and 878; compare Parry, C. and D., 53, 708.

Soden, Arch. Pharm., 238, 353; compare Miiller, Arch. Pharm., 238,
366; Schimmel & Co., Semi-Annual Report, April, 1900, 43.

3Beckurts and Troeger, Arch. Pharm., 235, 518 and 634; 236, 392; com-
pare Beckurts and Nehring, Arch. Pharm., 229, 612; Herzog, Arch. Pharm.,
148, 146.

*Tapia, Bull. Soc. Chim., 19 [III.], 638.

5
¥

ZINGIBERENE NITROSITE. 429

the refractive index, np = 1.4953, and a rotatory power, [4]>=
— 2.21°. Its glacial acetic acid solution gives a rose coloration,
changing to deep violet, on the addition of a few drops of sulphuric
acid.

The commercial “white oil” of caparrapi oil also contains a
monobasic acid, C,,H,,O,, which crystallizes in white needles, melts
at 84.5°, and has the specific rotatory power, [a],= + 3°. Itis
sparingly soluble in cold water, soluble in hot water, and readily
soluble in alcohol. Its calcium salt, Ca(C,,H,,0,), + 5H,O, ecrys-
tallizes in needles, melting at 250°; the silver, sodium, and am-
monium salts are crystalline.

13, ZINGIBERENE, C,,H,,.
The sesquiterpene, C,,H,,, which is the chief constituent of the

5249
oil of ginger, has been studied by Soden’ and by Schreiner and
Kremers.”

It is obtained by the repeated fractional distillation of ginger
oil under reduced pressure, and is a colorless and almost odorless
oil; it boils at 134° (14 mm.), 160° to 161° (32 mm.) and at
269° to 270° under atmospheric pressure. It has the sp. gr.
0.872 at 15° or 0.8731 at 20°, the refractive index, np = 1.49399,
at 20°, and the specific rotatory power, [a], = — 69° to — 73.38°
(100 mm. tube).

Zingiberene dihydrochloride,’ C,,H,,-2HCl, is obtained by satur-
ating a solution of zingiberene in an equal volume of glacial acetic
acid, cooled to 0°, with dry hydrochloric acid gas, and allowing
to stand during one or two days; it crystallizes from hot alcohol
in fine, white needles, which melt at 168° to 169°.

Zingiberene nitrosochloride,*’ C,,H,,,NOCI, is formed when a
mixture of zingiberene, glacial acetic acid and ethyl nitrite is
cooled in a freezing mixture and is treated gradually with a satur-
ated solution of hydrogen chloride in glacial acetic acid ; the
nitrosochloride is precipitated by shaking the reaction-product
with alcohol and is purified by dissolving in ethyl acetate and
reprecipitating with alcohol. It forms a white powder and melts
with decomposition at 96° to 97°. 7

Zingiberene nitrosite,’ C,,H,,-N,O,, results when the sesquiter-
pene is dissolved in ten times its volume of petroleum ether, the
solution well cooled and treated with a solution of sodium nitrite
and glacial acetic acid. It crystallizes from hot methyl alcohol
in fine needles and melts at 97° to 98°.

1H. von Soden and Rojahn, Pharm. Zeit., 45, 414.
Schreiner and Kremers, Pharm. Arch., 4, 141 and 161.
2Schreiner and Kremers, Pharm. Arch., 4, 161.

430 THE TERPENES.

Zingiberene nitrosate, C,,H,,-N,O,, is prepared by dissolving
zingiberene in an equal volume of glacial acetic acid and ethyl
nitrite, cooling in a freezing mixture, and carefully treating with
a mixture of nitric and glacial acetic acids; the product is pre-
cipitated by shaking with cold alcohol. The nitrosate is purified
by dissolving in acetic ether and precipitating with alcohol ; it
forms a yellow powder, which melts and decomposes at 86° to
88°.

Zingiberene unites with bromine, forming a liquid tetrabromide

(Soden).

14. OLEFINIO SESQUITERPENE, C,,H,,, FROM THE OIL OF

15) 2a
CITRONELLA.

According to Schimmel & Co.,' citronella oil contains a “ light
sesquiterpene” which appears to bear the same relation to the
sesquiterpenes proper, as do the olefinic terpenes to the cyclic
terpenes.

This sesquiterpene boils at 157° (15 mm.), has the sp. gr.
0.8643 and index of refraction, np = 1.51849, at 15°; it is dex-
trorotatory, [a], = + 1° 28’. Under ordinary pressure, it boils
with decomposition at 270° to 280°.

It is readily decomposed by the action of the halogens or halo-
gen hydrides. It has an odor similar to that of cedar wood, and
is oxidized by dilute permanganate solutions, yielding carbon
dioxide, oxalic acid and a glycol. It is acted upon by a mixture
of glacial acetic and sulphuric acids, forming a product having a
saponification-number of 43.6.

During the year 1901, Kremers? suggested a classification of
the sesquiterpenes according to which these hydrocarbons, C,,H,,,
may be separated into five groups as follows.

Group I. Sesquiterpenes having an open-chain of carbon atoms
and containing four double linkages. An example of this class
is possibly to be found in the “light sesquiterpene” obtained by
Schimmel & Co. from citronella oil.

Group II. Monocyclic sesquiterpenes having three double link-
ages. This group probably includes zingiberene and the sesqui-
terpene obtained by Semmler from the oil of Carlina acaulis.

Group ITI. Dicyclic sesquiterpenes having two double linkages.
This class embraces most of the sesquiterpenes, including cadinene,
caryophyllene and probably humulene.

1Schimmel & Co., Semi-Annual Report, Oct., 1899, 23.
2Schreiner and Kremers, Pharm. Arch., 4, 141.

METATEREBENTENE. 431

Group IV. Tricyclic sesquiterpenes having one double linkage.
Clovene belongs to this group.

Group VY. Tetracyclic sesquiterpenes without a double linkage.
Representatives of this class are not at present known.

A further division of Group II. may be made according to
whether the ring contains three, four, five or six carbon atoms.
Groups III., 1V. and V. may likewise be subdivided according
to the number of carbon atoms contained in the ring.

Many sesquiterpenes are known which have not been mentioned
in the preceding pages ; but they probably consist, in part at least,
of mixtures of the above described hydrocarbons, although they
may also contain chemical individuals which have not yet been
characterized as such. Such sesquiterpenes are found in the prod-
ucts of the distillation of caoutchouc,' and in the polymerization-
products of valerylene,? C,H,. Many ethereal oils also contain
sesquiterpenes of an unknown nature.

DITERPENES, C,,H,,.

Very many diterpenes are known, but they have never been
thoroughly characterized. Hence, only a brief enumeration of a
few of these compounds which have been investigated will be
given in the following.

Colophene is formed by the action of concentrated sulphuric
acid* or phosphoric anhydride‘ on oil of turpentine, and also by
heating turpentine oil with benzoic acid,’ and by the distillation
of colophonium.® It is an oily, viscid liquid,‘ boils at 318° to
320°, and unites with hydrogen chloride, producing a very un-
stable compound.

Metaterebentene’ is produced ‘by heating turpentine oil at 300°.
It is an oily, viscous liquid, is optically levorotatory, and boils
above 360°; it has a specific gravity of 0.913 at 20°, and absorbs
hydrogen chloride. Meta-australene is prepared from dextro-
pinene in the same manner that metaterebentene is obtained from
levo-pinene.

1Bouchardat, Bull. Soc. Chim., 24, 108; compare Himly, Ann. Chem., 27,
40; Williams, Jahresb. Chem., 1860, 495.

2Bouchardat, Bull. Soc. Chim., 33, 24; Reboul, Ann. Chem., 143, 373.

Deville, Ann. Chem., 37, 192.

4Deville, Ann. Chem., 71, 350.

5Bouchardat and Lafont, Compt. rend., 113, 551; Ber., 1891, 904, Ref.

6Riban, Ann. Chim. Phys. [5], 6, 40; Armstrong and Tilden, Ber., 1879,
1755.

7Berthelot, Ann. Chim. Phys. [3], 39, 119.

432 THE TERPENES.

Dicinene’ is obtained by the action of phosphoric anhydride on
wormseed oil ; it boils at 328° to 333°.

Diterpilene* is formed when oil of turpentine is heated with
crystalline formic acid for twelve hours, or when limonene is
allowed to remain in contact with formic acid at the ordinary
temperature for some time. It is a thick oil, is optically inactive,
and has an odor like that of balsam of copaiba; it boils at 212°
to 215° under 40 mm. pressure, and has the sp. gr. 0.9404 at 0°.
It readily changes into a resinous mass on exposure to the air; it
combines with hydrogen chloride, forming a semi-solid of the com-
position C,,H,,-HCl.

Paracajeputene * is produced by the action of phosphoric anhy-
dride on the oil of cajeput ; it boils at 310° to 316°, dissolves in
ether, but is insoluble in alcohol and turpentine oil.

Diterpene* is obtained by heating terpine hydrate with phos- —
phoric anhydride or hydriodic acid ; it isa thick, oily liquid, which
boils at 320° to 325°, and has a specific gravity of 0.9535 at 0°.
It unites with hydrogen bromide and chloride, forming additive
compounds, and also yields a yellow, amorphous nitro-product.

TRITERPENES, C,H,,.

Several well characterized compounds which occur in elemi-resin
belong to the class of triterpenes. When elemi-resin is washed
with alcohol, the resinous substances are dissolved, and a crystal-
line compound is obtained ; this has been investigated by many

chemists, and is called amyrin. Vesterberg’s® detailed investiga-

tion showed that amyrin, purified by recrystallization from alcohol,
consists of a mixture of two isomeric triterpene alcohols, C,,H,,OH.
The separation of these alcohols is effected by boiling amyrin,
which is obtained from elemi-resin in a yield of 16.5 per cent.,
with acetic anhydride, and crystallizing the resultant acetyl com-
pounds from ligroine ; the crude acetyl derivative melts at about
200°. By fractional crystallization of the crude acetyl compound,
two substances of different crystalline form are obtained, the one,
f-amyrin acetate, consisting of aggregates of prisms, the other,
a-amyrin acetate, separating in single leaflets. Both acetates may
be obtained in a condition of chemical purity by repeated recrystal-

1Hell and Stiircke, Ber., 1894, 1973.

2Lafont, Compt. rend., 106, 140; Ber., 1888, 138; Bull. Soc. Chim., 49,
17; Ber., 1888, 605, Ref.; Bouchardat and Lafont, Compt. rend., 107, 916;
Ber., 1889, 9, Ref.

3Schmidt, Jahresb. Chem., 1860, 481.

4Berkenheim, Ber., 1892, 686.

5Vesterberg, Ber., 20, 1242; 23, 3186; 24, 3834 and 3836.

TRITERPENES. 433

lization from petroleum ether or benzene. Pure a- and f-amyrin
are secured by the saponification of the pure acetates.

The total amount of a-amyrin in the crude amyrin is about
sixty-six to seventy-five per cent.

a-Amyrin, C,,H,OH, crystallizes in long, lustrous, elastic
needles, which are quite readily soluble in ethyl acetate, ether,
benzene and hot alcohol, but are sparingly soluble in cold alcohol
and ligroine. It melts at 181° to 181.5°, and is optically dextro-
rotatory, [a] p= + 91.59°.

8-Amyrin, C,,H,.OH, shows a striking resemblance to the a-
modification, but is more difficultly soluble in alcohol, and melts
at 193° to 194°, It is dextrorotatory, [a], = + 99.81°.

The acetates of a- and f-amyrin have already been men-
tioned.

Both a- and f-amyrin are apparently secondary alcohols.
When oxidized with chromic acid, they yield the corresponding
ketones (or, possibly, aldehydes), a- and 8-amyrone, which, on treat-
ment with hydroxylamine, are readily converted into oximes,
C,,H,, : NOH.

When a- or f-amyrin is dissolved in petroleum ether and
treated with phosphorus pentachloride, a- or S-amyrilene, C,,H,,,
is formed ; both modifications are optically dextrorotatory. Levo-
rotatory a-amyrilene is obtained by treating a solution of a-amyrin
in benzene with phosphorus pentoxide.

By the action of bromine on a- or f-amyrin, or their acetates,
substitution products are produced.

When a-amyrin acetate is subjected to the action of chromic
anhydride in glacial acetic acid solution, it yields oxy-a-amyrin
acetate, C,,H,,O(OCOCH,) ; this is converted into oxy-a-amyrin,
C,,H,,O(OH), by hydrolysis. The analogous compound of the
f-series has not been isolated in a condition of purity (Vester-
berg’).

the properties of a- and f-amyrin and their derivatives are
given in the following table.

Almost all amyrin derivatives give characteristic colors with
Liebermann’s cholesterine reagent (acetic anhydride and concen-
trated sulphuric acid), the bromine compounds giving a blue, and
the others a violet or purple-red coloration. Thesecolors are best
shown by dissolving about one milligram of the substance in a
few drops of chloroform, adding five to ten drops of acetic anhy-
dride and one or two drops of concentrated sulphuric acid, and
then warming very gently.

1Vesterberg, Ber., 24, 3836.
- 28

434

THE TERPENES.

According to O. Hesse,’ 8-amyrin occurs as the palmitic acid
ester in the wax obtained from Trujillo coca and Java coca.

Palmityl-@-amyrin, C,,H,,O,, melts at 75°, and has the specific
rotatory power, [a], = + 54.5°.

a-Series.

B-Series.

Amyrin, C,,H,OH.

Ampyrin acetate,
C59 HgOCOCHs.

Amyrin benzoate,
Cy9H,gOCOC,H;.

Bromoamyrin,
C,,H,,BrOH.

Bromoamyrin acetate,
Cs HygBrOCOCHs.
Amyrilene, Cs Hy, pre-
pared by means of phos-
phorus pentachloride.

Levo-a-amyrilene,
CpHys, prepared by
means of phosphoric
oxide.

Melting point, 181° to
181.5°; slender needles ;
one part of a-amyrin
dissolves in 21.36 parts
of 98.3 per cent. alcohol
at 19° to 19.5°.

[a]p = + 91.69.

Melting point, 221°;
large plates.
[e]n= + 77.0°.

Melting point, 192°;
needles or flat prisms.

Melting point, 177° to
178°; slender needles.
[aJo>=+ 72.8°.

Melting point, 268°; tab-
lets or flat prisms.

Melting point, 135°; ve
sparingly soluble in al-
cohol; crystallizes from
ether in splendid, thick,
rhombic prisms, and
sometimes separates in
sphenoidal hemihedral
crystals.

Axial ratio,
a:b:¢=0.66733 :1:
0.40489.

[a]p = + 109.5°.

Melting point, 193° to
194° ; sparingly soluble
in ether, more readily
in hot ligroine, and
quite easily in hot ben-
zene; at 5°, however,
only one part of the hy-
drocarbon is soluble in
fifty-nine parts of ben-
zene. It separates in
rhombic crystals.

a: b:c=0.789 : 1: 0.505.
[a]p =— 104.9°.

Melting point, 193° to
194°; 5 — Psi:
one part of #-amyri
dissolves in 36.44 hea
of 98.3 per cent. alcohol
at 19° to 19.5°.

[e]p> = + 99.8°.

Melting point, 236°;
long prisms.

[c]n=+ 78.6°.

Melting point, 230°;
leaflets.

Melting point, 182° to
186° (2): gelatinous.

Melting point, 238°;

BY porno

elting point, 175° to
178°; crystallizes from
benzene in long, slender,
rhombic prisms.
a:b:ce=0.91655:1:
0.54032.
{@]p = 4- 111.8°.

}Hesse, Ann. Chem., 271, 216.

TETRATEREBENTENE HYDROCHLORIDE. 435

a-Series.

B-Series.

Amyrone, C,,H,,0.

Melting point, 125° to
130°; it separates from
a mixture of alcohol and
glacial acetic acid in
crystals containing one
molecule of water of
crystallization; dissolves
readily in ether, hot
benzene and __ glacial
acetic acid, sparingly in
cold benzene and glacial
acetic acid and more dif-
ficultly in alcohol.

Melting point 178° to
180°; forms nodular
aggregates of small
prisms which do not
contain water of crystal-
lization, and are readily
soluble in chloroform,
ether, benzene and gla-
cial acetic acid, spar-
ingly in ligroine and
alcohol.

RE

Amyronoxime, Melting point, 233° to| Melting point, 262° to
CyH,,;NOH. 234°; needles, readily | 263°; leaflets, insoluble

soluble in hot benzene,| in alcohol, sparingly
sparingly in alcohol! soluble in ligroine and
and ether, insoluble in| ether, quite readily in
eit etherand pot-| hot benzene.
ash.

Oxyamyrin, Melting point, 207° to

¢,,H_,0(OH)-+2H,0. ‘| 208°; contains two mole-
cules of water of crystal-
lization which are slowly
evolved at 100° ; readily
soluble in benzene,
ether and alcohol, spar-
ingly in petroleum ether.
[a]p>=+ 108.6°. .

Melting point, 278°; | Melting point, 240° (?).
crystallizes from ben-
zene in six-sided plates,
which belong to the
sphenoidal - hemihedral
division of the ortho-
rhombic system.

TETRATERPENES, C,,H,,.

Tetraterebentene is formed, together with colophene, when French
oil of turpentine is shaken with twenty to twenty-five per cent. of an-
timony chloride at a temperature not exceeding 50° (Riban'). Itis
a transparent, amorphous mass, and has a specific gravity of 0.977 ;
it is optically levorotatory, has a conchoidal fracture, and is soluble
in ether, carbon bisulphide, ligroine, benzene and turpentine oil, in-
soluble in alcohol. It melts above 100°, is not volatile at 350°,
and yields colophene and a terpene, C,,H,,, when it is distilled.

Tetraterebentene hydrochloride, C,,H,,.HCl,is formed when hydro-
chloric acid gas is led over pulverized tetraterebentene. The dihy-
drochloride, C,,H,,"2HCl, is obtained when hydrogen chloride is
passed into a well cooled, ethereal solution of tetraterebentene.
The latter compound and the corresponding dihydrobromide are
amorphous (Riban’).

1Riban, Ann. Chim. Phys. [5], 6, 40.

Oxyamyrin acetate,
1301 4x (OCOCH, ).

= —
=
-_e~

—

ih
A

Ht
,
f

IN DEX.

A
Absinthol= Thujone, 225
Acetaldehyde, 398
om acid, 71, 129, 158, 200, 224, 264, 265,

277
Acetone, 218, 243, 392, 406
Acetoxylene, 158
oxime, 158
Acetyl bornylamine, 341
carvomenthylamine, 358, 365
ee nine, 358
a-Acetyl-s, 6-dimethyladipic acid, 403
hydrogen ethyl] ester, 403
semicarbazone, 403
Acetyl fencholenamine, 352
enchylamine,
menthonylamine, 413
d-Acetyl menthylamine, 371
Spare menthylamine, 368
Acetyl neobornylamine, 345
inylamine, 337
Acid, C7H1002, 183
dibromide, 183
CsH1204, 47
CsH120s, 196
CsH14O2, 214
CoH1604, 289
CioHi6O2, 246

4N, 306
Ci2HisOs, 423
CisH 2603, 429
‘ calcium salt of, 429
Acid a-camphylamine oxalate, 346
Acroléin, 399
Addition-product of cineole and iodol, 326

Alcohol, CioHi90H, 316
; Aldehyde, bao ge gam camphene gly-
col,

from myrcenol, 378
oxime of, 378
semicarbazone of, 378
Allolemonal, 405
Amidocamphene, 66
eamphor, 152
2-hexahydrocymene=Carvomenthyl-
amine, 290, 36.
menthol, 306
menthone, 241, 305
menthonoxime, 306
hydrochloride, 306
phellandrene, 111, 374
hydrochloride, 375
mercuriochloride, 375
platinochloride, 375
sulphate, 375

Amidoterebentene, 338
hydrochloride, 339
oxalate, 339
platinochloride, 339
sulphate, 339

p-Amidothymol, 188, 189, 211

Amine, C9 i3N He, 232
derivatives of, 232

CoHizNHa2, 232
carbamide of, 232
CioHi7N Ha, 115
derivatives of, 115
CioHisON, 181
C10H150.N Ha, 115
CioH21ON, 352
CioHisBr.NHOH, 270
nitroso-derivative of, 270
CioHi;Br2.NHOH, hydrobromide,
270, 271
C2oH3sCINe, 302
hydrochloride, 302

Aminodecoie acid, 289, 303

Ammonium a-fencholenate, 164

a-Amyrilene, 433

B-Amyrilene, 433

l-a-Amyrilene, 433

Amyrin, 432

derivatives, table of, 434

a-Amyrin, 433

acetate, 432
benzoate, 434
p-Amyrin, 433
acetate, 432
benzoate, 434
palmitate, 434

Amyrol, 428

a-Amyrone, 433

p-Amyrone, 433

a- and p-Amyronoximes, 433

Anethol, 156

Anhydride of cis-pinole glycol, 278, 280
of triisonitroso-methyl-cyclohex-

anone, 242
Anhydrocamphenilic acid, 64
camphoic acid,63
dimethyltricarballylic acid, 52, 55
fenchocarboxylic acid, 169
geraniol, 379, 392
hexabromide, 379
Aurantiol = Linalool, 381
Australene, 34
Auto-oxidation of carvone, 193

, Beckmann and Pileissner’s “ hydrated

ulegonoxime,’’ CioHigNO2, and its
Terk vatives, 240
Beckmann’s reagent, 113
Benzoyl bornylamine, 341
campholamine, 353

: 437

Benzoyl a-camphylamine, 346
carvoxime, 191
4-Benzoyl-a- carvylamine, 356
p-carvylamine, 356
Benzoyl-a-d-carvylamine, 355
a-]-carvylamine, 356
p-d-carvylamine, 356
p-l-carvylamine, 356
carylamine, 359
dihydrocarvylamine, 358
dihydroeucarvylamine, 360
dipentene nitrosochloride, 96
fencholenamine, 352
fenchylamine, 349
hydrochlorocarvoxime, 192
limonene nitrosochloride, 76
menthylamine, tertiary, 374
neobornylamine,
pinylamine, 338
pulegonamine, 363
Benzyl! bornylamine, 342
hydrochloride, 342
methiodide, 342
platinochloride, 342
dihydrocarveol, 211
fenchylamine, 350
hydrochloride, 350
nitroso-derivative of, 350
latinochloride, 350
Benzylidene bornylamine, 342
breroonere 342
platinochloride, 342
earvone, 193
dihydrocarvone, 211
dihydrocarvoxime, 211
dihydroisocamphor, 252
eucarvone, 200
fenchylamine, 350
hydrochloride, 350
menthone, 306
hydrobromide, 306
hydrochloride, 306
menthonoxime, 306
menthylamine, 306
d-Benzylidene menthylamine, 372
l-Benzylidene menthylamine, 369
Benzylidene menthyl carbamate, 312
nopinone, 54
pinylamine, 338
pulegone, 342
Benzyl menthol, 306
menthone, 307
menthonoxime, 307
menthylamine, 307
pulegol, 243
Bisnitroso-4-bromotetrahydrocarvone, 208
Bisnitrosocarvone, 209, 220
menthone, 304
pulegone, 342
pulegonoxime, 342
tetrahydrocarvone, 288
Bispulegone, 243
Borneo-camphor, 142
Borneol, 141
bromal derivative of, 144
chloral derivative of, 144
derivatives, table of, 149
Borny] acetate, 143
Bornylamine, 135, 340, 343, 344

488 INDEX.

Bornylamine, acetyl derivative of, 341
acid sulphate, 341
ee as derivative of, 341
benzylidene derivative of, 342
derivatives, tables of, 345
formyl] derivative of, 341
hydrobromide, 341
hydrochloride, 340
picrate, 341
platinochloride, 341
tartrate, 341
Bornylamines, 340
Borny1] butyrate, 148
carbamide, 342
methyl derivative of, 342
phenyl derivative of, 342
chloride, 144
Bornylene, 121
oxidation of, 121
Borny] esters, table of, 143
ethyl ether, 144
formate, 143
iodide, 40, 145
methylearbamide, 342
methylene ether, 144
methyl ether, 143
phenylearbamide, 342
phenylthiocarbamide, 342
phenylurethane, 144
propionate, 143
thiocarbamide, 342
valerate, 143
xanthic acid, 144
Brominated lactone, 164, 166
Bromoamyrin, 433, 434
acetate, 433, 434
Bromocamphene, 62
2-Bromocymene, 184
Bromofenchone, 159
nitrocamphane, 66, 123
Nate Raa dean 5 hexenoie acid,

Bromopernitrosocamphor, 153
pinic acid, 56
1-Bromo-A*®)-terpene, 93, 271
nitrosobromide, 93, 271
A (8)-terpene, 93
nitrosobromide, 93
Bromotetrahydrocumie acid, 53
Butyryl fenchylamine, 349
d-Butyryl menthylamine, 371
l-Butyryl menthylamine, 369

Cadinene, 414, 424
dihydriodide, 416
dihydrobromide, 416
dihydrochloride, 416
nitrosate, 417
nitrosochloride, 416
oxidation of, 415

Cajeputene, 85

Cajeputol = Cineole, 323

Calcium cineolate, 327

INDEX. 439

Camphene, bromo-derivative of, 62
chloro-derivative of, 62
dibromide, 62
a-dichloro-derivative of, 62
glycol, 63, 151
glycol, aldehyde from, 151

ydriodide, 61
hydrobromide, 61
hydrochloride, 61
nitrates, 65
nitronitrosite, 60
nitrosite, 60
oxidation of, 63

a-Camphene phosphorous acid, 59

g-Camphene phosphorous acid, 59

Camphene, tribromo-derivative of, 62

Camphenilanaldehyde, 60, 65, 152

Camphenilanic acid, 65, 151

Camphenilene, 64

Camphenilic acid, 63, 65

Camphenilic nitrite, 60, 64

renee, 61, 64
alcohol, 64
alcohol, chloride of, 64
oxime, 64
semicarbazone, 64

Camphenol = Carvenone, 62

7-Camphenol = Borneol, 142

ses enone, 152

ibromide, 153
hydrobromide, 153
monobromo-derivative of, 153
oxime, 153
pernitroso-derivative of, 153

é dibromide = Dibromoperni-
trosocamphenone, 153

Camphenylnitramine, 251

Camphenylone = Camphenilone, 61, 64

Camphocenie acid, 64

Camphocenic nitrile, 64

Camphoceonie acid, 64

Camphoic acid, 63

Camphol aleohol, 152

Campholamide, 141

Campholamine, 141, 353
benzoyl! derivative of, 353
hydrochloride, 152, 853
nitrate, 353
platinochloride, 353

a-Campholenamide, 136

B-Campholenamide, 139

a-Campholenamidoxime, 136

Campholene, 137, 140, 353

a-Campholenic acid, 136

p-Campholenic acid, 139

a-Campholenie amide, 136

p-Campholenic amide, 139

a-Campholenonitrile, 135, 346

p8-Campholenonitrile, 139, 347

Campholic acid, 141, 353

Campholic amide, 141

Camphol, instable = Isoborneol, 146

Campholonie acid, 139

Campholonitrile, 141, 353

Camphol, stable = Borneol, 146

Campholyl phenylthiocarbamide, 353

Camphopyric acids, 64, 69,

Camphopyric anhydride, 63, 64, 69, 71

Camphor, 133

waaay oe = Pinene hydrochlor-
ide,
condensation-products of, 141
derivatives, optical properties of, 150
Camphor dioxime, 135
Camphor, oxidation of, 134
liquid, 83
Camphorie acid, 64, 134
Camphoronie acid, 134
Camphoroxime, 135
action of nitrous acid on, 135
me? tc =a-Campholenonitrile, 135,

ethyl ether of, 135
phenyl cyanate derivative of, 135
sodium salt of, 135
Camphor pinacone, 141
Camphor semicarbazone, 140
Camphoylic acid, 63
Camphrene, 134, 217
we ean = Dihydrocamphene, 39,

a-Camphylamine, 136, 346
acid oxalate, 346
benzoyl derivative of, 346
dichromate, 346
dithiocamphylcarbamate, 347
hydrochloride, 346
mercuriochloride, 346
oxalate, 346
picrate, 346
platinochloride, 346
sulphate, 346
p-Camphylamine, 139, 347
Camphylamines, 346
a-Camphyl phenylthiocarbamide, 347
thiocarbimide, 347
Caoutehin, 85
hydrate = Terpineol, 258
Caoutchoue, distillation of, 31, 87
Caparrapene, 428
Caparrapiol, 428
Carbanilido-carvoxime, 191
isocarvoxime, 191
Carbofenchonone, 169
dioxime, 169
monoxime, 169
Carboxyl-apocamphoric acid, 63
Caronbisnitrosylic acid, 209, 220
Carone, 219
bisnitroso-derivative of, 220
dibromide, 220
oxidation of, 222
Carone semicarbazones, 220
cis-Caronic acid, 222
anhydride, 222
trans-Caronic acid, 222
Caronoxime, 220
Caro’s reagent, 300
Carvacrol, 44, 134, 179, 189, 191, 199, 207,
221
Carvacrylamine, 190, 191, 228
hydrobromide, 210
Carvanol, 219, 293
Carvanone = Tetrahydrocarvone, 219, 291,
293

Carvene = d-Limonene, 71, 72
Carvenol = Carvenone, 62, 219, 293
D-d-Carvenolie acid, 182

at q

440 INDEX.

I-l-Carvenolic acid, 182
Carvenolic acid, inactive, 182
Carvenolic acids, 182
dibromides of, 183
= acid, C;H,)04, from,

Carvenolides, 182
dibromides of, 182
Carvenone, 62, 134, 207, 216
benzylidene derivative of, 218
nitroso-derivative of, 217
oxidation products of, 218
semicarbazones, 217
Carvenonoxime, 217
Carveol = Carvenone, 212, 216
Carveoloxime = Carvenonoxime, 210
Carveol methyl ether, 73, 178, 197, 260
addition products of, 198

_ Carvestrene, 103, 359

dihydrobromide, 104
dihydrochloride, 104
ortho-, 104
pseudo-, 104
Carvol = Carvone, 178
Carvomenthene, 124, 292
hydrobromide, 125
hydrochloride, 125
Feoeentnet =Tetrahydrocarveol, 291,
3

tertiary, 293, 316
Carvomenthone= Tetrahydrocarvone, 238,
254, 287
Carvomenthy] acetate, 293
Carvomenthylamine = Tetrahydrocavyl-
amine, 111, 290, 364
acetyl derivative of, 365
formy! derivative of, 365
hydrochloride, 365
platinochloride, 365
tertiary, 373
benzoyl derivative of, 374
chloroaurate, 374
a ean pe 374
platinochloride, 374
Carvomenthyl bromide, 293
tertiary, 317
carbamide, 365
chloride, 293
iodide, tertiary, 316
phenylearbamide, 365
phenylthiocarbamide, 365
tertiary, 374
Carvone, 74, 178, 279
and derivatives, table of, 197
benzylidene derivative of, 193
compound with acetoacetic ester, 194
dichloride, 183
dihydrodisulphonate of sodium, 193
dioxime, 193
diketone from, 193
hydrobromide, 180, 198
hydrochloride, 180
hydrogen sulphide, 179
oxymethylene derivative of, 194
pentabromides, 183
phenylhydrazone, 184
reduction products of, 194
semicarbazones, 193
semioxamazone, 193

Carvone sodium‘dihydrodisulphonate, 193
semicarbazone, 193
tetrabromides, 1
tribromide, 181
Carvotanacetone, 236
hydrogen sulphide, 237
ortho-, 237
oxaminoxime, 237
oxidation of, 237
pseudo- = Terpenone, 237
semicarbazone, 237
Carvotanacetoxime, 237
Carvoxime, 184
and derivatives, table.of, 187
benzoyl derivative of, 191
earbanilido-, 191
derivatives of, 184
hydrobromide, 192
hydrochloride, 191
benzoyl derivatives of, 192
Carvoxime, inactive, 190
iso- 190
Carvylamines, 354, 355, 356
erivatives of, 355, 356
Carylamine, 220, 358
benzoyl derivatives of, 359
hydrochloride, 103, 359
Caryl phenylthiocarbamide, 359
Caryophyllene, 417
acetate, 420
alcohol, 417, 419
bisnitrosate, 419
bisnitrosite, 418
bisnitrosochloride, 418
bromide, 420
chloride, 420
dihydrochloride, 417
iodide, 420
isonitrosite, 418
nitrate, 421
nitrolamines, 419
benzylamines, 418, 419
piperidide, 419
nitrosate, 418
nitrosite, 418
nitrosochlorides, 418
Caryophyllene phenylurethane, 420
Cedar camphor = Cedrol, 423
Cedrene, 423, 424
Cedrol, 423
acetate, 424
Cedrone, 424
oxime, 424
acetate, 424
Champacol = Guaiol, 426
Chavicol, 377
Chlorhydrins, 40, 282
Chloride, CioHisCl, 208, 228
a-Chlorocamphene, 62
hydroe loride, 62
sulphonic chloride, 62
Chlorocamphydrene, 39
3-Chlorocymene, 298
2-Chlorocymene, 184
Chlorodihydrocymene, 298
fenchene, 159
a horie acid, 158
fenchone hydrochlorides, 158
ketones, 281, 288

6 Wed arth) Ae he RO ep ot Ashe AN iy Lhe

et «ere

INDEX.

Chloromethyl menthyloxide, 311
2-Chloropulegone, 242
3-Chloro-a?(*®)-terpadiéne, 243
tetrabromide, 243
Chlorotetrahydrocymene, 298
Cholesterine reagent, 433
Cinene, 85
Cinenic acids, 332
derivatives of, 332
Cineole, 323
addition-product with iodol, 324,
3826

with naphtol, 324
compound with phosphoric acid, 324
dibromide, 326
diiodide, 326
hydrobromide, 325
hydrochloride, 324, 325
oxidation of, 326
Cineolic acid, active, 333
anhydride of, 334, 405
derivatives of, 333
inactive, 326, 333
amides, 328, 331
anhydride of, 328
derivatives of, 327, 328, 333
esters of, 327
oxidation of, 331
Cineolic allylamide, 328 *
anhydride, 328
anilide, 328
diethylamide, 328
ethyl ester, 327
methyl ester, 327
para-toluidide, 329
eek. ape 329
piperidide, 328
A, silver salt of, 328
Cinnamic aldehyde, 399
Cinogenic acid, 332
Citral = Geranial, 396
a= Geranial a, 400
_ 6=Geranial 6, 401
Citralidene (geranialidene) bisacetylace-
tone, 405
Citrene, 71
Citriodoraldehyde, 405
Citronellal, 409
acid sodium sulphite, 409
dibromide, 410
dimethyl] acetal, 411
disulphonic acid derivative, 410
monosulphonic acid derivative, 410
B-naphthocinchonic acid, 411
hydrochloride, 411
p-naphthyl quinoline, 411
normal sodium bisulphite, 410
oxidation of, 410
oxime, 412
phosphoric acid, 411
semicarbazone, 412
sulphonie acids, 410
Citronellamide, 412
Citronella pimelic acid, 412
Citronellic acid, 401, 410, 412
. dioxy-, 412
Citronellol, 389, 394, 410
acetate, 396
chlorinated phosphoric acid ester, 395

441

Citronellol diphenylurethane, 396
formate, 396
hydrogen phthalate, 395, 396
oxidation of, 396
Citronellone = Citronellal, 409
Citronellonitrile, 412
Citronellylidene cyanoacetie acid, 411
Clovene, 417, 418, 421
Coca wax, 434
Colophene, 431
hydrochloride, 431
Colophonium, 35, 87
Compound, CsH9Cl.OH, 33
1H1004Na, 111
CioHicO or CioHisO, 343
CioHieOa, 159
CioHisBr, 159
Ci0H220s, 293
CioHisCle, 391
CioHsOBre, 299
CioHisN202, 193
CioH20N202, 217
CioHisBr(OCHs), 197
CioHis0O.H3sPOu, 324
CioHi702.0C2H5, 401
CioHis.2CrO2Cle, 65
CuHisO, 41
CuH20NO2Cl, 98
CuHirNO, 169
CizHaaNO2Cl, 98
CizH20BrOs, 279
CigH25C104, 194
C20Hs40, 248
Ca0Hs1O2, 254
C2HssN.HBr.Bra, 343
C2sH2402, 200
C24Ha6O2, 218
Condensation-product, CiuHisO, 83,

98

CisH27N Oz, 351

C24H2g02, 290

of eucarvone and _ benzaldehyde,

Copal resin, 35, 87
Coriandrol = Dextro-linalool, 383
m-Cresol, 246
Cubeb camphor, 424
Cubebene, 424
Cumic acid, 122
Cuminaldehyde, 122
Cuminy] alcohol, 122, 205
Cupric menthylxanthate, 312
Cuprous menthylxanthate, 312
Cyclodihydromyrcene, 379
dibromide, 379
ketonic acid from, 379
Cyclogeranial, 403, 404
derivatives of, 404 . ,
Cyclogeranialidene cyanoacetic acids,

404, 405 ¥
Cyclogeranic acids, 402, 403, 405
derivatives of, 402
Cyclogeraniolenes, 404
Cyclogeranionitriles, 403, 404 ee
Cycloheptylenamine, formyl derivative
of, 244
Cyelolinalolene, 880, 130
Cymene, 85, 160, 398
Cymylhydroxylamine, 189, 190

442 INDEX.

D

Decenoic acid=Menthonenic acid, 289,
802, 303
Decoie acid, 303
-amide, 303
Dextro-linalool, 383
menthone, 315
Dextrorotatory menthone, 297
Diacetate of glycol, CioHis(OH)s, 391
Diamidophellandrene, 375
ss Aegan wie 376
platinochloride, 376
salts of, 376
Diamine, 306
hydrochloride, 306
Diaterpenylic acid, 196 ‘
Diaterpenylic lactone = Terpenylie acid,
196
Diazo-camphor, 152
Dibasic acid, CoH160x, 295
ic min dihydrocarvyldiamine, 358
Dibenzylidene menthenone, 251
alcohol from, 251
Diborneolic formal, 146
Dibornylamine, 343
hydrochloride, 343
isomeride of, 343
nitrate, 343
nitrite, 343
platinochloride, 343
Dibornylthiocarbamide, 342
Dibromide from fenchyl alcohol, 173
1, 6, 2, 8-Dibromodioxyhexahydrocymene,
277

Dibromomenthone, 299
oxime, 299
Dibromopernitrosocamphor, 153
4, 8-Dibromoterpen-1-ol, 270
acetate, 93, 270
1, 8-Dibromotetrahydrocaryone, 221
Dicarboxylic acid, C11HisO4, 169
Dicarvelones, 194, 195, 212
dihydrobromides, 195
oximes, 195
acetyl derivatives of, 195
phenylhydrazones, 195
Dichloride from fenchyl alcohol, 173
a-Dichlorocamphene, 62
Dichlorocarvone, 183
Dichlorodipentene, 91
dibromide, 91
dihydrochloride, 91
hydrochloride, 90
nitrolanilide, 91
piperidide, 91
nitrosochloride, 91
Dichlorotetrahydrocaryone, 221
Dicinene, 432
Diethyl hexamethylene, 132
aleohol, 132
iodide, 132
ketone, 132
Dieucarvelone, 196, 200
isomeride of, 196
oxime, 196
phenylhydrazone, 196
Difenchone, 170

Dihydriododipentenes, 94
Dihydrobromodipentenes, 91
Dihydrocamphene, 123
Dihydrocampholene, 138
Dihydrocampholenimide, 139
Dihydrocampholenolactone, 136, 140
Dihydrocarveol, 184, 212, 358
acetic acid, 211
ethyl ester, 211
hydrobromide, 214
oxidation of, 214
Dihydrocarvone, 155, 194, 206
acid sodium sulphite, 206
benzylidene derivative of, 211
dibromide, 207, 208, 221
dichloride, 209, 221
ketone-glycol from, 212
semicarbazone, 212
hydrobromide, 207, 220
hydrochloride, 208
oxidation of, 212
oxymethylene derivative of, 211
semicarbazone, 211
tribromide, 209 —
Dihydrocarvoxime, 209
ydrobromide, 210
isomeride of, 210
Dihydrocarvyl acetate, 214
hydriodide, 214
Dihydrocarvylamine, 112, 184, 188, 213, 356
acetyl derivative of, 358
benzoyl derivative of, 358
dihydrochloride, 357
formyl] derivative of, 357
hydrochloride, 213, 357
oxalate, 358
sulphate, 358
Dihydrocarvyldiamine, 358
derivatives of, 358
Dihydrocarvyl methyl] xanthate, 213
phenylearbamide, 358
phenylthiocarbamide, 358
phenylurethane, 213
Dihydrochlorodipentenes, 89
dichloride, 91
Dihydrocuminy] alcohol, 122
Dihydrocumie acid, 54
Dihydrocymene, 22, 27
Dihydrodicamphene, 123
Dihydroencarveol, 200, 223, 224
acetate, 224 ‘
chloride, 224
Dihydroeucarvone, 223
nitroso-derivative of, 223
' oxidation of, 223
semicarbazone, 223
Dihydroeucarvoxime, 223
driodide, 223, 293, 359
Dihydroeucarvylamine, 223, 359
enzoyl derivative of, 360
Syatoohioraes 360
platinochloride, 360 : ,
wii cnet ce + phenylearbamide, 360
thiocarbamide, 360
Dihydrofencholene, 164
Dihydrofencholenamide, 167
Dihydrofencholenic acid, 167
Dihydrofencholenic lactam =8- Isofen-

Difenchyloxamide, 349
thiocarbamide, 349

ehonoxime, 168

INDEX.

Dihydrofencholenonitrile, 167
Dihydroisocamphor, 252
acid sodium sulphite, 252
benzylidene derivative of, 252
semicarbazone, 252
Dihydroisothujol = Thujamenthol, 236,
95

2
Dihydromyrcene, 379
eyclo-, 379
diketone from, 379
keto-glycol from, 379
Dihydropseudocumene, 231
Dihydroxylene, meta-, 330
Diisonitroso-methyl-cyclohexanone, 242
diacetate, 242
Diisoprene, 85
Diketone, CoHuO2 211, 212
dioxime of, 211, 212
semicarbazone of, 212
CioH1402, 193
1, 3-Diketone, C10H16O2, 310
dioxime of, 310
Dimentholic formal, 310
Dimenthyl, crystalline, 313
liquid, 313
methylal, 310 :
a, a-Dimethyl adipic acid, 402
8, B-Dimethyl adipic acid, 402
gem-Dimethy] adipic acid, 294
1, 2, 4-Dimethyl ethyl benzene, 120
Dimethyl fenc ae hydriodide, 349
a, a-Dimethyl 5 utaric acid, 403
2, 6-Dimethyl heptan-5-onic acid, 218
oxime, 218
Dimethyl he tenol, 392
isopro lt lene oxide, 232
_ &Dimethy vulinie acid, 231
w-Dimethy] laevulinic acid, 231
oxime, 231
$- or w-Dimethy] laevulinic methyl ketone,
230, 233
. oxime, 231
Dimethyl malonic acid, 158, 163,294
2, 6- octadiéne-2, 6-acid-8 = Geranic

acid, 407
2, 7-0l-6 = Linalool, 383
2, 6-al-8 = Geranial, 407
gare 2, 6-ol-8 = Geraniol, 383, 392
_ 2, 6-Dimethy] octane-2, 8-ol, 394, 413
; 3-onoie acid, 310
Dimethyl-2, 6-octene-2-al-8 = Citronellal,
41

01-8 = Citronellol, 396
octylene glycol, 303, 394, 413
2, 6-oximido-3-octanic acid = Menth-
oximic acid, 304, 305, 310
as-Dimethyl succinic acid, 55, 64
gem-Dimethyl succinic acid, 120, 200,
223, 224, 294
Dimethyl] thujylamine, 361
hydrochloride, 361
nitrate, 361
platinochloride, 361
tricarballoylformiec acid, 55
tricarballylic acid, 51, 55, 64, 158.
gem - Dimethyl trimethylene -1, 2-dicar-
boxylic acid, 222
Dinitroeudesmole, 286
Diosphenol, 315.

443

Dioxime, CoH14(NOH)s2, 211
_ CioHia(NOH)s, 193
Dioxycamphoceanic acid, 64
Dioxycitronellic acid, 412
a- Dioxydihydrocampholenic acid, 136, 188
6-Dioxydihydroeampholenic acid, 139
Dioxydihydrocyclogeranic acid, 402
Dipentene, 85, 213, 358, 377
derivatives, table of, 100
dichloride, 91
dihydriodides, 94
dihydrobromides, 91
dihydrochlorides, 89
hydrochloride, 89
nitrolamines, 96
a-Dipentene nitrolanilide, 96
nitroso-derivative of, 97
8-Dipentene nitrolanilide, 97
nitroso-derivative of, 97
a-Dipentene nitrolbenzylamine, 97
nitrolpiperidide, 96
8-Dipentene nitrolpiperidide, 96
Dipentene nitrosochlorides, 95
benzoyl derivatives of, 96
Dipentene nitrosate, 96
tetrabromide, 94
tetrachloride, 91
tribromo-derivative of, 92
trichloro-derivative of, 90
Diterpene, 432
Diterpenes, 431
Diterpilene, 432
hydrochloride, 432
Dryobalanops camphora, 142

E

Elemi resin, 87, 108, 432

Essence of resin, 87

Ethoxybromocarvacrol, 227

Ethyl bornyl ether, 144
camphene, 65
6-chloro-a-methoethy1ol-5-hexoate, 332
cineolic ester, 327
hydrogen cineolate, 327
isoborny] ether, 148
menthane, 314

Eucalyptene, 34

Eucalyptol, 324

Eucarvone, 181, 198
benzylidene derivative of, 200
oxidation of, 200
phenylhydrazone, 199
semicarbazone, 200

Eucarvoxime, 199

Eudesmol, 285
dibromide, 286
dinitro-derivative of, 286
oxidation of, 286

Eugenol, 377

Euterpene, 120, 224

dihydrobromide, 120

F
Fenchelene, 120
Fenchene, 66, 171
D-d-Fenchene, 67
D-i-Fenchene, 67
I-d-Fenchene, 67
I-i-Fenchene, 67

————

444 INDEX.

Fenchene alcoholate, 68
dibromide, 68
hydriodide, 68
hydrobromide, 68
hydrochloride, 68
oxidation products of, 68
Fenchenole, 177
hydrobromide, 177
Fenchimine, 166
hydrochloride, 167
picrate, 167
Fenchocamphorol, 69
Fenchocamphorones, 69, 70
nitriles of, 69, 70
oxidation products of, 69, 70
oximes of, 69, 70
semicarbazones of, 69, 70
Fenchocamphylamine, 69
Fenchocarboxylic acids, 168, 169
a-Fencholenamide, 162
g-Fencholenamide, 165
Fencholene alcohol = Fencholenyl alco-
hol, 176, 352
Fencholenamine, 162, 163, 351
acetyl derivative of, 352
benzoyl derivative of, 352
nitrate, 352
oxalate, 352
sulphate, 352
Fencholenfurfuramide, 352
a-Fencholenie acid, 159, 163, 166
amide = a-Isofenchonoxime, 162
hydrobromide, 164
hydrochloride, 164
salts of, 164
sodium salt of, 164
B-Fencholenic acid, 165
B-Fencholenic acid hydrobromide, 166
salts of, 166
sodium salt of, 166
a-Fencholenonitrile, 161, 165, 351
g-Fencholenonitrile, 161, 165
Fencholenyl alcohol, 176, 352
Fenchone, 155, 224
bromo-derivative of, 158, 159
isopernitroso-derivative of, 166
oxidation of, 158
pernitroso-derivative of, 166
semicarbazone, 160, 166
Fenchonimine nitrate, 166
Fenchonitrimine, 166
Fenchonoxime, 160
action of nitrous acid upon, 166
anhydride, 161, 351
derivatives of, 162
hydriodide, 162
hydrobromide, 162
hydrochloride, 162
hydrochloride, 161
Fenchy] alcohol, 170
D-l-Fenchy] alcohol, 67, 171
at Sab alcohol, 67, 171
Fenchy1 alcohol derivatives, table of, 175
alcohol, iso-, 174
Fenchylamine, 159, 161, 347
acetyl derivative of, 349
benzoyl derivative of, 349
benzyl! derivative of, 350
benzylidene derivative of, 350

Fenchylamine, butryl derivative of, 349
fenchylcarbamate, 348
formy! derivative of, 347, 348
hydriodide, 348
hydrochloride, 348
a pa ela derivative of

sitar has deena derivative of,

neutral oxalate, 348
nitrate, 348
nitrite, 348
oxalate, 348
o-oxybenzylidene derivative of, 351
p-oxybenzylidene derivative of, 351
picrate, 348
platinochloride, 348
propionyl derivative of, 349
sulphate, 348
table of compounds, 351
tartrate, 348
Fenchyl acetate, 172
benzoate, 172
benzylamine, 350
nitroso-derivative of, 350
bromide, 173
carbamide, 349
D-d-Fenchyl chloride, 173
D-l-Fenchyl1 chloride, 173
Fenchy] chloride, secondary, 173
tertiary, 67, 172
ydrogen phthalate, 172
ydrogen ate, 1
iodide, 173.
o-methoxybenzylidene amine, 351
p-methoxybenzylidene amine, 351
methylamine, 349
nitroso-derivative of, 350
oxamide, 349
o-oxybenzylidene amine, 351
p-oxybenzylidene amine, 351
phenylthiocarbamide, 349
phenylurethane, 172
thiocarbamide, 349
Formyl] bornylamine, 341
ecarvomenthylamine, 365
dihydrocarvylamine, 357
d-Formyl menthylamine, 371
i-Formyl menthylamine, 368
neobornylamine, 345
Furfuro-pinylamine, 338
-fencholenamine, 352

Galipene, 428
ydrobromide, 428
Galipol, 428
Geranial, 377, 396, 405
acid sodium sulphite, 397
anilide, 399
-(citral-) a, 400
- @, semicarbazone, 400 .

b, 401
b, naphthocinchonic acid, 401
b, oxime, 401
b, semiearbazone, 401
dihydrosulphonic acid derivatives,398 _
Geranialidene bisacetylacetone, 405
cyanoacetic acid, 404, 405

INDEX,

b-Geranialidene cyanoacetie acid, 405
Geranial-8-napthocinchonie acid, 399
hydrochloride, 399
Geranial, oxidation of, 405, 406
oxime
phenylhydrazone, 399
polymeride of, 405
semicarbazones, 400
sodium (om von normal, 398
hydrosulphonate, 398
tetrabromide, 398
Geranic acid, 401
a- and p-cyclo-, 402
Geraniol, 383, 387
calcium chloride derivative of, 387,
388, 390
oxidation of, 392
Geraniolene, 402
tetrabromide, 402
Geranionitrile, 401
amidoxime of, 404
Geranyl acetate, 392
anilide, 399
bromide, 391
dihydrobromide, 391
chloride, 391, 395
diphenylurethane, 393
tetrabromide, 393
hydrogen phthalate, 390, 393
silver salt of, 393
tetrabromide, 393
succinate, 390
iodide, 391
phenylhydrazone, 399
Geronic acid, 402, 404, 405, 408
semicarbazone, 404
Glycerol, Co9H17(OH)s, 233
Glycol, CsHsBre(OH)s, 32
CioHi16(OH )2, 263
diacetate, 263
CioHis(OH)2, 207, 214, 220, 391
diacetate, 214, 391
CroH2002, erystalline, 315
liquid, 315
Gonorol, 426
Guaiol, 426

acetate, 426
Guttapercha, distillation of, 31

; H
Hemiterpenes, 17, 31
Heptylenamine, cyclo-, 244
Hesperic acid, 83
Hesperidene, 71
trans-Hexahydro-1, 3, 5-carvacrol, 315
Hexahydrocymene, 18, 130, 131, 309, 322
Hexahydro-meta-toluidine, formyl de-
rivative of, 244
Homocamphorie acid, 133
Homolimonene, 211
Homoterpenoylformie acid, 54
oxime of, 55
Homoterpenylie acid, 54, 55
Humulene, 421
bisnitrosite, 422
isonitrosite, 422
nitrolamines, 422, 423
nitrolbenzylamine, 422, 423
hydrochloride, 422

445

Humulene nitrolpiperidide, 422,
Brapoehioride, 422
_ platinochloride, 422
nitrosate, 422, 423
nitrosite, 422, 423
nitrosochloride, 422, 423
Hydrated ss. wane = Pulegone hy-
roxylamine, 239, 240
acetyl derivative of, 241
benzoyl derivative of, 241
hydrochloride, 241
oxalate, 241
Hydrazocamphene, 65
ej ‘iguana aad 228, 293,

Hydriodofenchonoxime anhydride, 162
Hydro-aromatic acids, behavior of, 215
Hydrobromocarvone, 180, 198
dibromide, 181
keto-amine of, 181
Pit cal ad sen 181
Hydrobromocarvoxime, 181, 192
dihydrocarveol, 214
dihydrocarvone, 207
dihydrocarvoxime, 210
dipentene dibromide, 92
fencholenic acids, 164, 166
fenchonoxime anhydride, 162
pinole dibromide, 278
pulegone, 239
pulegonoxime, 239
Hydrocarbon, CoHi6, 245
nitrosochloride of, 245
CioH 4, 358
CioH16, 379
CioHis, 130, 380
CioH20, 131, 315
CioH22, 379
CisHes, 416
Ci7He2, 211
Cs0H50, 421
Hydrocarbons, C1oHis, 123
CioH20, 130
Hydrochlorocarvone, 180
henylhydrazone, 180
Hydroch orocarvoxime, 191
benzoyl derivative of, 192
Hydrochlorodihydrocarvone, 208
Hydrochlorodipentene, 89
dichloride, 90
nitrolamines, 97
anilide, 97
benzylamine, 98
p-toluidide, 98
nitrosate, 97
nitrosochloride, 97
Hydrochlorofencholenamide hydrochlor-
ide, 352
fencholenic acid, 164
fenchonoxime, 161
anhydride, 162 |
Hydrochlorolimonene, 80
nitrolamines, 82
anilide, 82
benzylamine, 82
nitrosate, 81
nitrosochloride, 81
Hydrochloronitrosodipentene ethyl] ether,
98

446 INDEX.

Hydrochloronitrosodipentene methyl
ether, 98
Hydrochloropulegone, 239
Hydrocyanie acid, 158
Hydroxycamphene, 66
Hydroxycamphoronie acid, 51
Hydroxylaminocarvoxime, 192
dibenzoy1 derivative of, 192
diphenylearbamide, 193
diphenylthiocarbamide, 193
picrate, 192

I

Inactive carvoxime, 96, 190
menthol, 312, 315
pulegone, 239
Instable camphol = Isoborneol, 146
Jonone, commercial, 407 ‘
a-lonone, 407
oxime, 407
semicarbazone, 407
B-Ionone, 405, 408
oxime,
semicarbazone, 408
Trone, 408
Isoamidocamphor, 136, 139
Isoborneol, 146
bromal derivative of, 149
chloral derivative of, 149
derivatives, table of properties, 149
Isobornyl acetate, 148
chloride, 150
Isobornylene, 121
Isobornyl ethyl ether, 148
formate, 148
methylene ether, 148
methyl ether, 148
phenylurethane, 149
Isobromopernitrosocamphor, 153
Isobutyl camphene, 65
Isobutylidene diaceto-acetic ester, 27
Isobutyric acid, 158
Isobutyryl ethyl methyl ketone, 230
ketoxime, 231
methyl ketopentamethylene, 310
y-Isobutyryl 8-methyl valeric acid = Oxy-
menthylic acid, 129, 310
Isocamphenilanic acid, 65
Isocamphenol, 171
Isocamphenone, 153
oxime, 153
Isocamphol, 58, 146
Isocamphopyrie acid, 63
Isocamphor, 166, 251
bisnitrosochloride, 252
dihydro-, 252
oxime, 166, 252
semicarbazone, 166, 252
tetrahydro-, 252
B-Isocamphor, 253
phenylurethane, 253
Isocamphoranie acid, 52
Isocamphoreniec acid, 52 .
Isocamphorone, 139
Isoeamphoronie acid, 51, 55, 158
Isocamphoroxime = a-Campholenamide,
136

Isocarveol = Pinocarveol, 201, 202

Isocarvyone = Pinocarvone, 201
Isocaryoxime, 190
benzoyl derivative of, 191
earbanilido-, 191
Tsocedrol, 424
benzoate, 424
Isodihydrocamphene, 124
Isofencholenyl alcohol, 163, 176
a-Isofenchonoxime, 162
B-Isofenchonoxime = Dihydrofencholenie
acid lactam, 163
B-Isofenchonoxime, salts of, 163
Isofenchyl alcohol, 68, 174
acetate, 174
derivatives, table of, 175
formate, 175
hydrogen phthalate, 175
ketone from, 175
aleohol from, 175
oxime, 175
henylurethane, 175
Isogeronic acid, 402, 403, 404, 408
semicarbazone, 403, 404
Isoketocamphorie acid, 51
Isomenthol, 309, 314
Iso-/-menthonoxime, 301
Isomenthyl benzoate, 314
Isomeric terpineol, m. p. 69° to 70°=
A4(8)-Terpen-1-ol, 269
m. p. 32° to 33° = A8® -Terpen-
1-ol, 273
nitrolamines, 274
piperidide, 274.
nitrosochloride, 274
oxy-ketone from, 274
phenylurethane, 274
thujonoxime, m. p. 90°, 228
thujylamine, 361
Isonitrosocamphor, 152
menthone, 307
pulegone, 242.
Isopernitrosofenchone, 166, 252
Isopinole dibromide, 253, 279
Isoprene, 31
- dibromhydrin, 33
dibromide, 32
dichlorhydrin, 32
dihydrobromide, 32
dihydrochloride, 32
hydrobromide, 32
alcohol from, 32
hydrochloride, 32
alcohol from, 32
dibromide, 32
“ phates yes wee 32 eles
a-lsopropyl glutaric acid,
7 anhydride, 253
anilide, 253
5-Isopropy! heptan-2-onie acid, 288
oxime, 288
a-Isopropylidene-aY-hexenoie acid, 333
g-Isopropy] laevulinic acid, 236, 295
Isopropyl succinie acid, 236, 237, 288,
2

89
Tsopulegol, 247, 410
acetate, 247
Tsopulegone, 247, 248

a-Isopulegone, 249
B-Isopulegone, 248

INDEX.

Isopulegone derivatives, table of, 250
semicarbazones, 249
Isopulegonoximes, 249
Tsosantalenes, 427
Isoterebentene, 85
a-Isotetrahydrocarvoxime, 289
Bey np caryoxine, 290
sothujaketonic acid, 236
oxime, 236
semicarbazone, 236
jamenthonoxime, 294
ujene, 119, 360
ujolacetic acid, 235
Isothujone, 157, 235
oxidation of, 236
oxime, 228, 235
semicarbazones, 235
Beye, 362
hydrochloride, 362
nitrate, 362 |
Isothujyl carbamide, 362
phenylearbamide, 362
phenylthiocarbamide, 362
Tsovaleric acid, 392

K

Keto-amine, 181
derivatives of, 181
Ketodihydrocymenes, 22
Ketohexahydrocymene, 19, 24
a-Keto-isocamphoronic acid, 55
Keto-lactone, CioH1eOs, = Methoethylhep-
tanonolide, 263
oxime, 264
semicarbazone, 264
= Methyl ketone of homoter-
penylic acid, 221, 267
CioHi6Os, 48, 49, 52, 295
oxime, 295
Ketomenthone, 307
oxime, 308
Ketone, CioH140, 212 os
CioHi60, 155, 212, 258
oxime, 253
Ketone alcohol, CioH1602, 47
oxime, 47
Ci0H170.0H, 129
acetate, 207
oxime, 129
E phenylurethane, 129
Ketone glycol, 212
semicarbazone, 212
Ketonie acid, CsH120s, 71
derivatives of, 71
CoH120s, 403
semicarbazone, 403
CioHis0s, 294, 295
oxime, 294
semicarbazone, 294, 295
een aroeysbogeranic acid,

semicarbazone, 402
Ketopentamethylenes, 133
pinie acid, 39
hydrazone, 39
oxime, 39
Ketotetrahydrocymenes, 20
Keto-terpine, 209

447

L

Lactone, C7Hi20s, 230
CioHieO2, 169, 246
e-Lactone, CioHisQO2, 300
derivatives of, 300
Lactonic acid, C7H1004, 243
CioHi604, 218
Laevulinic acid, 392, 406
Laurene, 34
Lavendol = Linalool, 381
Ledene, 425
chloride, 425
Ledum camphor, 425
Lemonal = Geranial, 396
Lemonol = Geraniol, 384, 389, 392
Levo-camphenol, 58, 142
Levorotatory menthone, 297
Licareol = Linalool, 381
Licarhodol = Geraniol, 387, 389
1-Licarhodol, 405
Liebermann’s cholesterine reagent, 433
Limonene, 71, 213
chloro-derivative of, 80
derivatives, optical properties of, 85,

hydrochloride, 80
nitrolamines, 76
anilides, 77
table of, 78
benzylamines, 79
piperidides, 79
nitrosate, 76
nitrosobromide, 76
nitrosochlorides, 74
and compounds derived from
them, table of, 186 b
cee acta benzoyl derivatives
of, 76
ortho-, 84
oxidation products of, 83
pseudo-, 84, 85, 114
tetrabromide, 72, 73, 197:
Limonenol, 83, 203
tetrabromide, 203
Limonenone, 204
oxime, 204
Limonetrol, 84, 334
Linalolene, 380, 385
eyelo-, 380
Linalool, 377, 381
dextro- = Coriandrol, 383
oxidation of, 386
properties, table of, 382
sodium salt of, 384
Linalyl acetate, 386
butyrate, 387
d-Linaly] chloride, 386
Linalyl chlorides, 385
d-Linaly] iodide, 386
Linalyl propionate, 387
sodium phthalate, 384
valerianate, 387

M
Massoyene, 34
Matricaria camphor, 133
Mentha camphor, 308
Menthadiénes, 24
Menthandiol-3, 8, 248

448 INDEX.

67 pada Soe 24, 130,

131
cis-Menthane-1, 2-dichlor-6, 8-diol, 40, 282
Menthane, meta-, 131 ,
Menthan-2-ol = Carvomenthol, 291
3-0l = Menthol, 308
2-one = Carvomenthone, 287
3-one = Menthone, 295
1, 2, 6, 8-tetrol, 277, 282
triol, 266
Menthene, 24, 126, 308, 313, 315, 370, 372
A8)-Menthene-1, 2-diol, 263
diacetate, 263
Al-Menthene-6,8-diol = Pinole hydrate, 277
A®6-Menthene-2,8-diol= Pinole hydrate, 277
Menthene glycol, 129, 323
diacetate, 129
monoacetate, 129
terpene, CroFhie, from, 129
Menthene hydriodide, 314
hydrobromide, 314
hydrochloride, 313
meta-, 130
nitrolbenzylamine, 128
nitrosate, 128
nitrosochloride, 128
A&-Menthene-2-one, 181, 253
dioxime, 254
hydrogen sulphide, 254
oxaminoxime, 254
oxalate, 254
oxime, 254
semicarbazone, 254
Menthenone, 129, 250, 304
alcohol from, 251
dibenzylidene derivative of, 251
hydrogen sulphide, 251
nitroso-derivative of, 251
phenylhydrazone, 251
pinacone from, 251
Menthobisnitrosylic acid, 304
Menthocitronellal, 303, 409
8-naphthocinchonie acid, 409
Semicarbazone, 409
Menthocitronellol, 303, 380, 393, 413
acetate, 394
nitrous acid ester, 394
Menthoglycol, 248, 410
monoacetate, 248
Menthol, 239, 308, 368, 370, 372
cis-symmetrical, 315
inactive, 312, 315
iso-, 309, 314
liquid, 308
oxidation of, 309
sodium salt of, 310
solid, 308
benzoate, 308
sym-, 315
tertiary, 317
Menthonaphthene, 131, 309
Menthone, 238, 239, 295, 372
a-Menthone, 307
Menthone amine, 307
Menthone, benzylidene derivative of, 306
bisnitroso- derivative of, 304
bisnitrosylic acid, 304
carboxylic acid, 307
chloro-derivative, CioH17Cl, 298

Mantes chloro-derivative, CioHisCle,

dextro-, 315
dextrorotatory, 297
dibromo-derivative of, 299
dicarboxylic acid, 307
inactive, 297
levorotatory, 297
cepa i acid = Decenoie acid, 289,
s ,
amide, 302
Menthone, oxidation of, 299
oxymethylene derivative of, 305
pernitroso-derivative of, 304
pinacone, 307, 308
a-Menthone semicarbazone, 307
Menthone semicarbazones, 303
semioxamazone, 303
sym-, 308
semicarbazone, 308
sodium bisulphite, 308
Menthonitrile, 302, 393, 413
d-Menthonoxime, 301
Z-Menthonoxime, 300
d-Menthonoxime hydrochloride, 301
l-Menthonoxime hydrochloride, 300
Menthony] acetate, 394
alcohol = Menthocitronellol, 293, 394,

413
aldehyde=Menthocitronellal, 303, 409
amine, 303, 380, 393, 413
acetyl derivative of, 413
acid oxalate, 413
hydrochloride, 413
oxalate, 394, 413
oxamide, 413
oxyhydro-, 303, 393, 413
platinochloride, 413
Menthoximie acid, 304, 310
Menthy!] acetate, 311
acetoacetate, 311
phenylhydrazone, 311
d-Menthy] allylthiocarbamide, 372
d- (cis-) Menthylamine, 370
Z- (trans-) Menthylamine, 301, 368
d- (cis- ees acetyl derivative
or,
benzylidene derivative of, 372
butyryl derivative of, 371
formyl] derivative of, 370, 371
hydriodide, 371
hydrobromide, 371
hydrochloride, 371
o-oxybenzylidene derivative of, 372
propionyl1 derivative of, 371
Z-(trans-) Menthylamine, acetyl deriva- —
tive of, 368
benzylidene derivative of, 369
butyryl] derivative of, 369
formy! derivative of, 368, 370
hydriodide, 368
hydrobromide, 368
hydrochloride, 368
nitrite, 368
o-oxybenzylidene derivative of, 369
propiony1 derivative of, 369
Menthylamines, 298, 365 :
and derivatives, optical properties of,
373

INDEX.

Menthylamine, tertiary, 374
benzoyl derivative of, 374
chloroaurate, 374
h drochloride, 374
P tinochloride, 374
Menthyl benzoyl ester, 311, 314
bromide, 314
tertiary, 317
butyrate, 311
carbamate, 312
benzylidene derivative of, 312
d-Menthyl carbamide, 372
l-Menthyl carbamide, 369
Menthy! carbonate, 312
chloride, 313
dixanthate, 127, 313
ethyl ether, 311
7-Menthy1 eth { nitrosamine, 369
Menthyl! iodide, 314, 315
inactive, 315
tertiary, 317
yar a fo isobutyl nitrosamine, 369
Menthy! methy] ether, tertiary, 317
7-Men ‘pe met v1 nitrosamine, 369
Menthy! methyl xanthate, 312
phenyl carbamate, 312
d-Menthyl] phenyl carbamide, 372
i-Menthyl phenyl carbamide, 369
d-Menthy1 phenyl] thiocarbamide, 372
i-Menthy] pheny] thiocarbamide, 369
Menthy a thiocarbamide, tertiary,

phenylurethane, 312
phthaloxy] ester, 312
phthalyl ester, 312
7-Menthy] propy] nitrosamine, 369
stearate, 310
succinoxy] ester, 311
succinyl ester, 311
yl trimethyl ammonium hydrox-
, ide,
gegen trimethyl ammonium hydrox-
ide, 370.
ee trimethyl ammonium iodide,

37:
ated ‘trimethyl ammonium iodide,
poet trimethyl ammonium triiodide,

urethane, 312
- xanthic acid, 312
- methyl ester, 312
salts of, 312
Meta-australene, 431
dihydroxylene, 330
menthane = 1, 3-Methyl isopropyl cy-
clohexane, 131
menthene = 1, 3-Methy] isopropyl cy-
clohexene, 130
oxyhexahyd rotoluene, 245
oxy-para-toluic acid, 215
terebentene, 431
Methoethene-5-hexene-2-acid-6, 333
See aa ecmamolide, 52, 263, 266,

8-Metho-ethy]-2-hexene-dioic acid, 230

Methoethylol-5-hexene-2-acid-6 = ¢-Oxy-
isopropy]l-4Y-hexenoie acid, 332

Methoxybromocarvacrol, 227

29

449

Methoxybromocarvacrol acetyl ester
methyl ether 227 pein i
o-Methoxybenzylidene fenchylamine, 351
ey uidene fenchylamine, 351
. ef : apc acid, 129
-Methyl adipic acid, 243, 299,
396, 412 . sosapiatane
ee ean. ir
-aminoethyl-3-pentolide, 265
bornyl carbene, 342
borny] ether, 143
chavicol, 377
cineolic ester, 327
cyclohexanol, 245
1-cyclohexanol-6-methyl-acid-4, 215
cyclohexanone, 239, 244
oxime, 245
semicarbazone, 245
dihydrocarveol xanthate, 213
dihydrocarvy] xanthate, 74
1-dimethyl-5-cyclohexene-1-methyl-
acid-6, 403
Methylene porays ether, 144
isoborny] ether, 148
Methylenic acetal of borneol = Diborne-
olic formal, 146
of menthol = Dimentholic
formal, 310
Methy1-3"-ethy]-3-heptanon-6-olid-1, 31, 48,
49, 52, 263, 264, 266
oxime, 264
3-Methyl-ethy1-2-heptene-6-onoic acid, 229
Methyl-1-ethyl-on-4-cyclohexanol-6, 215
Methyl] eugenol, 377
fenchimine iodide, 167
fenchylamine, 349
hydriodide, 349, 350
hydrochloride, 350
nitroso-derivative of, 350
-gem-dimethyl cycloheptenone, 223
a-Methy] glutaric acid, 218
Methyl1-2-heptene-2-on-6, 407
heptenol, 330, 392
oxide, 331
heptenone = Methyl hexylene ketone,
330, 398, 405
heptenoncarboxylic acid, 406
2-Methy] heptone-3, aie 230

oxime, 23
Methyl heptylene carbinol, 177, 232
- ketone, 231
benzylidene derivative of, 231
oxime, 232
semicarbazone, 231
3-Methy] hexan-3-onoic acid, 231
Methyl hexenone, 244
hexylene carbinol, 177, 3380, 392, 406
ketone, 329, 330, 405
derivatives of, 330
oxide, 331
isoborny] ether, 148
cis-1, 3-Met 7) saeRPODs cyclohexanol-5,
1

hexanone-5, 308
hexane, 130
hexene, 131
3-Methy] isopropy]-a?-cyclohexenone car-
boxylie acid, 253
Methyl isopropyl hexahydrofluorene, 307

450 INDEX.

se - 6 - isopropyl-A?-keto-R-hexene,
16

2-Methyl] isopropyl! pyrroline, 231
Methyl rg pie trioxy hexahydroben-
zene = Trioxyterpane, 262
wie a of homoterpenylic acid, 221,

p-Methyl1 ketopentamethylene, 243
Methyl reo de aa 312
mercaptan, 313
2-Methyl-3-menthene he ee -6-one, 232
2-Methy]1 - 3 - methyl-ol-heptan-6-one-3-ol,
3

23
1- Methyl-4-propenyl - dihydroresorcinol,
193

Methyl pulegenate, 245
pulegonamine, 363
latinochloride, 364
3-Methy! pyrrolidine, 31
Methyl terpine, 318
acetate, 318
Monobasic acid, CoHicO, 331
methyl ester, 331
Monobromocamphene, 62
‘rel Sahar 153 -
cae hes dihydrobromide, 92
Monochloro dipentene dihydrochloride, 90
menthone, 304
Monoketazocamphadione, 152
camphor quinone = Diazocamphor,
152

Myrcene, 377
oxidation of, 378

Myrcenol, 378, 383
oxidation ‘of, 378

Myrcenyl acetate, 378

Naphthenes, 132
N eobornylamine, 344
acetyl derivative of, 345
benzoyl derivative of, 345
derivatives, table of, 345
formyl derivative o , 345
hydrochloride, 344, 345
platinochloride, 345
icrate, 345
Neobornyl carbamide, 345
phenylearbamide, 345
Nerolol = Linalool, 381
Ngai camphor, 142
Ngai fén, 150
Nitrocamphane, 123
Nitrocamphene, 66
Nitrofenchone, 158
Nitromenthone, 241, 305
Nitrophellandrene, 111, 374
Nitroxylene, meta- 330
Nitrosobenzy] fenchylamine, 350
Nitrosocarvenone, 217
Nitrosodihydroeucarvone, 223
Nitrosodipentene = Inactive carvoxime,
96, 190
a-nitrolanilide, 97
B-nitrolanilide, 97
Nitrosolimonene nitrolanilides, 79
Nitrosomenthene, 129, 251
Nitrosomenthenone, 251
Nitrosomenthone, 241

Nitrosomethyl fenchylamine, 350
Ni itrosopinene, 48, 154, 202, 336
dibromide, 155
N itrosopulegone, 242
Nitrosoterpene = Carvoxime, 184
Nitroterebentene, 339
Nomenclature, 23
Nopic acid, 53
Nopinole glycol, 41, 282
diacetate, 41, 282
Nopinone, 54
benzylidene derivative of, 54
oxime, 54
semicarbazone, 54
Norpic we 47, 56
hyde, 56
ppp Bites 56
silver salt of, 56

Ocimene, 379
Oil of absinth = ae of wormwood, 87,
108, 225, 415
andro ogon, 108
schoenanthus, 389
angelica, 108
angostura gokge poms 428
anise, star, 35, 1
artemisia Yates barrelieri), 225
asafetida, 415
balm, 397
basil, sweet = Oil of basilicum, 34,
35, "394, 379, 381
basilicum, French, 35, 324, 381
German, 34, 324, 379, 381
bay, 35, 108, 377, 397
bergamot, 71, 87, 381, 382, 386
betel leaves, 414
bitter fennel, 108
Blumea balsamifera, 142
buchu leaves, 130, 307, 315
Barosma betulina, 815
serratifolia, 315
cade, 414, 415
cajuput, 35, 258, 323, 43!
camphor, 35, 57, 87, 108, 257, 324, 414
Canadian ine, 142
cananga, oe: 381
Canella ear , 824, 417
eaparrapi, 42
caraway, 71, 178, 185, 219
cardamom, 87, 112, 257, 266, 324
Carlina acaulis, 430
cedar wood, 423

chenopodium = ‘i of wormseed,
American, 87, 43

cinnamon, 108, ‘son

citron = Oil of lemon, 34, 57, 71, 108,
381, 396, 409

citronella, 57, 150, 388, 409, 430

fruit, 397

cloves, 417, 419

clove stems, 417

cones of Abies — 34, 72

copaiba balsam, 4

INDEX.

Oil of coriander, 35, 383

coto bark, para=Oil of paracoto
bark, 414
cubeb, 87, 414, 424
cureuma, 108
dill, 71, 108, Eg
elderberry, 35 , 415
elemi, 108
erigeron, 71, 257
canadensis, 258
spree, f 323, 324

ina, 108
on ety citriodora, 397
camphora, 286
eloeophora, 286
globulus, 34, hg 266, 324
goniocalyx, 286
macarthuri, 388
macrorrhyucha, 386
maculata,
var. citriodora, 388, 409
piperita, 285, 286
smithii, 286
stricta, 286
staigeriana, 897
European pennyroyal (Mentha pule-
gium),
fennel, 35, 87, 155, 156
feverfew, 133°
fleabane = Oil of en 71, 257
frankincense = Oil of o libanum, 34,
87, 108, 414;

ee, 307

Indian = Oil of eo 388,
394, 395

rose=Oil of pelargonium, 388,
394, 395

Turkish = Oil of palmarosa, 388,
er a 5

gin

r, 57, 108, 429
gol mie te a7 108, 142, 415

gusiac wood, 42
emlock eke needle, 34, 57, 142
hops, 380
iva, 304”
ym 4 ee 34, 415
esso = Oil of valerian root, Jap-
anese, 35, 57, 257
kesso-root, '35, 87
kuromoji, "1, "87, 178, 257
Labrador tea, 425
laurel berries, ey 323
leaves, 34, 3
lavender, 35, 04, 381 382, 387, 388
lavender, s ike — Oil of spike, 35, 57,
142, 324,
ledum palustre = Ol of Labrador

tea, 42
lemon, 34, 57,71, 108, 381, 396, 409
grass, 388, 397,
Levant wormseed, "323
ee of limetta pans 87, 381,
limetta leaf, 87, 381, 382, 397
linaloe, 381, 382, 388

451

Oil of lovage, 266

mace, 34, 87
mandarin, 397
marjoram = Oil of sweet marjoram,
112, 257, 267
marsh tea = Oil of Labrador tea, 425
massoy bark, 35, 71, 87
Matricaria parthenium = Oil of fever-
few, 133
melissa = Oil of balm, 397
Mentha crispa, 185
pulegium = “bins of European pen-
nyroyal, 2.
myrcia = Oil of ee 35, 108, 377, 397
myrtle, 35, 87, 324
Wie ~Oil of orange flowers, 381,

niaouli, 35, 267
nutmeg, 35, 87
olibanum, 34, 87, 108, 414
orange flowers, 381, 386
peel, 71, 397
sweet, 71
Origanum. majorana=Oil of sweet
marjoram, 112, 257, 267
Smyrna, 380, 381, 382
palmarosa = Oil of East Indian gera-
nium, 388, 394, 395
paracoto bark, 414
parsley,
arti bs 414, 425
pelargonium, 388, 394, 395
pennyroyal, 237
American, 237
European, 237
Spanish, 238
pepper, Florida, 87, 108, 415
Japanese, 87, 108, 397
peppermint, 35, 72, 108, 127, 295, 308,
324, 415

American, 295
Russian, 285
petitgrain, 381, 388
pimenta, 397
pine needle, 142
from Abies alba, 34, 72, 142
siberica, 142
Picea excelsa, 34, 87, 108,
142, 414
nigra, 142
Pinus eeprom 34, 99,
108, 142, 414
. silvestris, 34, 99, 414
resin, 34
Pinus sibirica, 57
poplar buds, 422
pulegioides Persoon, 237
resin, 35
rose, '394, 395, 410
German, ” 388
Turkish, 388 |
rosema , 85, 57, 142, 323
sage, sa via ‘officinalis, 34, 142, 224,
323, 381
selarea, 142, 224, 323, 381
salviol = Oil of sage 224, 323
sandalwood, East ndian, 426, 427
West Indian, 428
sassafras bark, 35, 108

452 INDEX.

Oil of sassafras leaves, 35, 108, 377, 381,
387, 388, 397
satureja, 142
savin, 121, 204, 414
spearmint, American, 35, 72, 178
German, 35, 178
Russian, 35, 72, 178, 324, 381
spike = Oil of lavender, spike, 35, 57
142, 324, 381, 388
a Pca Oil of anise, star, 35,
1
sweet marjoram, 112, 257, 267
tansy, 35, 224, 225
thuja, 35, 155, 156, 224, 236, 237
thyme, 35, 87, 142, 381

—— American, 34, 57, 320,431,
f

French, 34, 266, 431, 434
German, 34
Russian, 34, 87,.99
Swedish, 34, 87, 99
valerian, 34, 142
Japanese = Oil of kesso, 35, 57,
257

verbena, 397
water fennel, 35, 108
wormseed, American, 87, 432
Levant =Oil of Levant wormseed,
323, 324
wormwood, 87, 108, 225, 415
ylang-ylang (Cananga odorata), 381,
388, 415

zedoary, 324
Olefinic alcohols, 381
aldehydes, 396
amines, 413
camphors, 28
hydrocarbons, 377
sesquiterpene from the oil of citro-
nella, 430
terpene in the oil of hops, 330
origanum, 380
terpenes, 28,377
Olibanum, 35
Olibene, 34
Ortho-diketone, C1oH1¢6O2, 309
isopulegol, 247
isopulegone, 246
terpenes, 84, 120
Oxalic acid, 158, 212, 222, 224, 277, 392
Oxide, CoHie02, 233
CoHi602, bromide of, 233
Oxy-acid, CsH140s, 274
Oxy-acid, CioHisOs, 403
a-amyrin, 433
a-amyrin acetate, 433
o-Oxy-benzylidene fenchylamine, 351
p-Oxy-benzylidene fenchylamine, 351
0-Oxy-benzylidene d-menthylamine, 372
l-menthylamine, 369
inylamine, 338
1-8- xy bromotetrahydrocarvone, 209, 221,
267, 291
Oxycamphene = Carvenone, 62
Oey came Saye acid, 65
camphoceonic acid lactone, 64
camphor, 136
carbofenchone=Carbofenchonone, 169
dioxime, 169

Oxy-oxime, 169
carone, 209, 221, 291
keto-terpine from, 221
oxime, 221
phenylhydrazone, 221
semicarbazone, 221
oxime, 221
phenylurethane, 221
semicarbazone, 221
Oxydihydrocarvone, 211, 277
semicarbazone, 211
Oxydihydrocarvoxime, 211, 262, 277
diacetyl derivative of, 211
Oxydihydrofencholenamide, 167
Oxydihydrofencholenic acid, 168
lactone, 168
Oxydihydrofencholenonitrile, 167
a-Oxydimethyltricarballylie acid, 55
lactone, 55
D-d-Oxyfenchenic acid, 70
acetyl derivative of, 70
D-l-Oxyfenchenie acid, 69
D-l-Oxyfenchenie acid, acetyl derivative

or,
LI-d-Oxyfenchenie acid, 70
Oxyfenchenic acid, racemic, 70
Oxygenated compound, Cro H160, 337
Oxy-2-hexahydro-p-cymene, 237
homopinie acid, 55
hydromenthonylamine, 303, 393, 413
isocamphoronie acid, 52
a-Oxy-isocamphoronie acid lactone, 55
a-Oxy-isopropyl-ay-hexenoie acid, 332
Oxy-ketone, 274
semicarbazone, 274
menthylic acid, 129, 299, 310
derivatives of, 310
oxime, 304, 310
methylene camphor, 140
methylene carvone, 194
methylene menthone, 305
; derivatives of, 305
Oxymethylene +tetrahydrocarvone, 221,
290

thujone, 229
a-Oxy-at-methyl-a-isopropyl-adipie acid,
218

Oxy-oxime, CioHis(OH)NOH, 181
$-Oxy-a-oxyisopropyl hexenoie acid, 332
Oxypinic acid, 56
Oxyterpenylic acid, 84, 196
dilactone, 84, 196

Oxytetrahydrocarvone, 214, 220

semicarbazone, 214

eymenes, 20, 21
Oxytrimethylsuccinie acid, 52

ig

Palmityl-g-amyrin, 434
Paracajeputene, 432
Parapulegone, 246
Paratoluic acid, 215, 274
Paraxylic acid, 158
Patchoulene, 425
Patchoul alcohol, 425
eamphor, 425

y-Pentylene glycol, 331
oxide, 331

INDEX,

Peppermint camphor, 308
Pernitrosocamphenone, 153
dibromide = Dibromopernitroso-
camphor, 153
Pernitrosocamphor, 153, 251
fenchone, 166
menthone, 304
thujone, 228
Phellandrene, 108, 377
diamine, 110, 375
dibromide, 109
nitrosite, 109, 364, 375
Phenyl bornylearbamide, 342
dihydrocarvylurethane, 213
Phenylurethane, C1;H2303N, 129
Picean-ring, 56
Pimelic acid, 230
-Pimelic acid, 310
inacone, C20Hs402, 170
Pinacoline, 329
Pinarin, 56
Pinene, 34
action of hypochlorous acid on, 40
of nitrous acid on, 41, 202
formaldehyde derivative of, 41
acetate, 41
benzoate, 41
dihydrobromide, 41
dihydrochloride, 41
behavior towards bromine, 44
perc de, liquid, 45

hydrobromide, 39
hydrochloride, 38
nitrolallylamine, 42
amines, 42
amylamine, 42
benzylamine, 43
piperidide, 42
propylamine, 42
_-” nitrosobromide, 42
chloride, 41
oxidation of, 46
phthalimide, 339
_ phthalamie acid, 339
picrate, 38
Pinenol, 202
acetate, 202 ~~
dibromide, 20
Pinenone, 203
dibromide, 203
semicarbazone, 203
Pinenonoxime, 203
benzoyl derivative of, 203
butyryl derivative of, 203
dibromide, 203
phenylearbimide, 203
Pine wood, 35, 87,99
Pinic acid, 53, 56
Pinocampholenamide 155
Pinoeampholenic acids, 50, 155 :
Pinocampholenonitrile, 154
Pinocampheol, 155
Pinocamphone, 154
; oxime, 154
semicarbazone, 155

453

Pinocamphonitrile, 154
migpesms ylamnine, 154
_ acetyl derivative of, 154

Pinocamphyl carbamide, 154
phenylurethane, 155

Pinocarveol, 201, 202, 338

Pinocarvone, 201
acid sodium sulphite derivative of,

hydrogen sulphide, 201
oxime, 201
semicarbazone,. 202
é-Pinodihydrocampholenolactone, 50
Pinole, 42, 47, 260, 274
bisnitrosochloride, 283
benzoyl] derivative of, 284
ethoxy] derivative of, 284
methoxyl] derivative of, 284
cis-Pinole dibromide, 278
Pinole glycols, 334
cis-Pinole glycol, 279
cis-trans-Pinole glycol, 279
d-cis-trans-Pinole glycol, 280, 282
cis-Pinole }yeol, anhydride of, 278, 280
1-chlorhydrin, 281
2-chlorhydrin, 40, 281
diacetate, 280
diethyl ether, 280
dipropionate, 280
hydrate, 260, 276, 334
diacetate, 277
cis-Pinole hydrate dibromide, 277
Pinole hydrate, oxidation of, 277
hydrobromide, 276
isonitrosochloride, 283
nitrolamine, 284
hydrochloride, 284
amines, 284
anilide, 285
benzylamine, 285
p-naphthylamine, 285
piperidide, 284
nitrosochlorides, 283
oxidation of, 285, 279
cis-Pinole oxide (Wallach’s anhydride of
cis-pinole glycol), 40, 280
tetrabromide, 279 :
tribromide, 253, 278
Pinolic acids, 49
Pinolol, 253
Pinolone, 253, 279
Pinolonoxime, 253
amine from, 253
carbamide of, 253
semicarbazone, 253
Pinonie acids, 48, 49, 53
derivatives of, 48, 49
keto-lactones from, 48, 49
oximes of, 48, 49, 53
phenylhydrazones of, 53
semicarbazones of, 48, 49
Pinononie acid, 47
oxime, 47
Pinoylformie acid, 54
derivative of, 54
henylhydrazone, 54
Pinylamine, 154, 202, 336
acetyl derivative of, 337
benzoyl! derivative of, 338

454 ; INDEX.

Pinylamine, benzylidene derivative of, 338
furfuro-derivative of, 338
hydrochloride, 337
nitrate, 201, 202, 336, 337
oxalate, 337
o-oxybenzylidene derivative of, 338
picrate, 337
platinochloride, 337
sulphate, 337
thiocyanate, 337

Pinylearbamide, 338

Polyterpenes, 17, 414, 431, 432

Propionyl fenchylamine, 349

d-Propionyl menthylamine, 371

l-Propionyl menthylamine, 369

Pseudoionone, 407
pulegone, 246

Pseudo-terpene alcohol, 205

Pseudo-terpenes, 84, 114, 121

Pulegenacetone, 243
benzoyl derivative of, 243
oxime, 243

Pulegenic acid, 245

amide, 245

bromo-lactone from, 246

ketone from, 246

methyl ester, 245
hydrochloride of, 245

oxime, 246

oxy-acid from, 246

oxy-lactone from, 246

Pulegenolide, 246

Pulegenonitrile, 245

Pulegonamine, 241, 362
benzoy1] derivative of, 363
hydrochloric acid derivative of, 363
methyl derivative of, 363
phenylthiocarbamide, 363

Pulegondioxime hydrate, 242

Pulegone, 237, 364
acid-sodium sulphite derivative of,

238
benzylidene derivative of, 342
bisnitroso-derivative of, 242
derivatives, table of, 250
dibromide, 245
dinitrosylic acid, 242
hydrobromide, 239
oxime of, 239
hydrochloride, 238
hydroxylamine, 240, 241
nitroso-amine of, 241
oxalate, 241
inactive, 239
isonitroso-derivative of, 242
methylamine, 363
oxidation of, 243
semicarbazone, 242
Pulegonoxime, CioHigNOz, hydrated
Beckmann and Pleissner’s oxime)
= Pulegone hydroxylamine, 240
hydrated, acetyl derivative of, 241
benzoyl derivative of, 241
hydrochloride, 241
CioHisNOH, normal, 240
hydrobromide, 239
Pulegylamine, 240, 362
hydrochloride, 363
oxalate, 362

Paleeys carbamine, 363
phenylearbamide, 363
Pyruvic acid, 237

Quinone from thujone tribromide, 227

R

Racemic-s-carvylamine, 356
8-carvylamine, 356

Reduction products of carvone, 194
Réuniol, 389, 394, 395
Rhodinal =Geranial, 388
Rhodinol = Geraniol, 388, 389, 394
Rhodinolic acid = Geranic acid, 406
Roseol, 388, 389, 394

Sabinene, 121
dibromide, 121
lycol, 121
etone, 122
semicarbazone, 122
Sabinenic acid, 122
Sabinol, 204
acetate, 204, 205
addition-products of, 205
Sabinyl glycerol, 205
Salviol = Thujone, 225
Santalal, 427
semicarbazone, 427
a-Santalene, 427
acetate, 427
dihydrochloride, 427
nitrolpiperidide, 427
nitrosochloride, 427
B-Santalene, 427
acetate, 427
dihydrochloride, 427
nitrolpiperidides, 427
nitrosochlorides, 427
Santalic acid, 427
a-Santalol, 426, 428
acetate, 426
B-Santalol, 426, 428
acetate, 426
Sesquiterpene alcohol, 427
alcohols, 414 M
Sesquiterpenes, 17, 414
sldaetestion of, 430
Silver cineolate, 327
a-fencholenate, 164
Sobrerol = Pinole hydrate, 276
Sobrerone = Pinole, 276
cis-Sobrerytrite (menthane-1, 2, 6, 8-tetrol)
= cis-Sobrerythritol, 40, 282
cis-trans-Sobrerythrite (menthane-1,2,6,8-
—— = cis- trans -Sobrerythritol,
7
hydrate, 277
cis-Sobrerythritol, 40, 282
cis-trans-Sobrerythritol, 277
Sodium carvone dihydrodisulphonate, 193
semicarbazone, 193
a-fencholenate, 164
geranial hydrosulphonate, 398
semicarbazone dihydrodisulpho-

nate, 398
linaloolate, 384, 387

INDEX. 455

Sodium mentholate, 310
menthylxanthate, 312
Stable camphol = Borneol, 146
Succinic acid, 64, 253
Sylvestrene, 99
dihydriodide, 102
dihydrobromide, 101
dihydrochioride, 99, 101
nitrolbenzylamine, 102
nitrosochloride, 102
reaction, 101, 103, 104
tetrabromide, 102
Symmetrical menthol, 315
cis-Symmetrical menthol, 315
derivative of, 316
menthone = 1, 3-methyl isopropyl cy-
clohexanone-5, 308
derivative of, 308
ata isoborneol = Fenchylalcohol,

pulegol, 247

pulegone = Ortho-iso(?)-pulegone, 246
benzylidene derivative of, 247
compound, CisH200, from, 247
derivatives, table of, 250
semicarbazone, 247

terpene, 120, 247

T

Table, Borneol and isoborneol, and their

derivatives, 149

Carvoxime and its derivatives, 187

Derivatives of bornylamine( Forster),
neobornylamine (Forster) and bor-
nylamine (Leuckart, Wallach), 345

Fenchyl alcohol and isofenchyl] alco-
hol, and their derivatives, 175

Isomerism in the limonene series, 78

Limonene and dipentene derivatives,
relations to oxidized compounds of
the terpene series, 100

Limonene -nitrosochloride and com-
pounds derived from it, 186

Properties of a- and gs-amyrin and
derivatives, 434

‘Properties of Byer) esters, 143

see eget of linalool from different
oils, 382 4

Pulegone, isopulegone, synthetical
or ortho-isopulegone and deriva-
tives, 250

Relation of terpineol (m. p. 35°) to
other terpene derivatives, 268

Rotatory powers of the limonene de-
rivatives, 86

Specific and molecular rotatory
powers of fenchylamine and deriva-

Ss veoif De aaplocnlax rotate

pecific and molecular rotatory pow-
ers of d-and /-menthylamines and
derivaties, 373

Specific rotatory powers of caryone
and its derivatives, 197 :

oo in the terpene series,

Transformations of the keto- and oxy-
hydrocymenes, 335
ne = Thujene, 118, 360

Re roncemngcn Lioanboxy tie acid, 205, 229,

anhydride, 230
8-Tanacetogendicarboxylic acid, 230
Tanacetogen dioxide, 233
Tanacetogenic acid, 234
Tanacetoketocarboxylic acids, 229
Tanacetoketone = Thujaketone, 232
Tanacetoketoximic acids, 231
Tanacetone = Thujone, 224
Tanacetophorone, 230
Tanacetyl alcohol = Thujyl alcohol, 234

amine = Thujyl amine, 227, 360
chloride = Thujyl chloride, 235
Terebentene, 34
Terebic acid, 51, 222, 264, 277, 406
Terephthalic acid, 64
Teresantalic acid, 428
Terpadiénes, 23
Terpane = Cineole, 324
= Hexahydrocymene, 23, 130
Terpanes, 130
Terpan-2-0l = Carvomenthol, 291
3-0l = Menthol, 308
Terpanols, 23
Terpan-2-one = Carvomenthone, 287
-3-one = Menthone, 295
Terpanones, 23
pin) seme 4, 8-triol = Trioxyterpane, 334
A1-Terpene = Carvomenthene, 124
A3-Terpene = Menthene, 126
Terpene from the resin of Indian hemp,

119
hydrochloride of, 119
Terpenes proper, 17, 34
transformations of, 122
A1-Terpen-8-ol, 189, 256
A1-Terpen-4-ol, 256, 261
A8()-Terpen-1-ol, 256, 273
derivatives of, 274
A4(8) -Terpen-1-ol, 93, 105, 269
acetate, 93, 106, 269
dibromide, 93, 270
nitrosobromide, 270
nitrosochloride, 270
dibromide, 270
nitrososochloride, 270
oxidation of, 273
Terpenols, 23
Terpenone, 237, 289
semicarbazone, 289
Terpenones, 23
Terpenylic acid, 196, 264, 267, 277
Terpilene = Terpinene, 58, 85, 112
Terpilenol = Terpineol, 258
Terpine, 318
cis-Te ine, 320
trans-Terpine, 319
Terpine acetate, 322
ydrate, 254, 320, 432
oxidation of, 322, 323
mono-acetyl ester, 322
methyl-, 318
acetate of, 318
oxidation of, 319
Terpinene, 172, 213, 357
nzoyl isonitrosite, 116
dibromide, 114
nitrolamine, 117

mn

456 INDEX.

| Terpinene nitrolamine, dibenzoyl deriva- Tetrahydrocarvone, oxidation of, 288

| i tive of, 117 oxymethylene compound of, 221, 290
i} nitrolamines, 116 semicarbazones, 290
Hi amylamine, 118 Tetrahydrocarvotanacetone = Tetrahydro
benzylamine, 118 earveol, 292
diethylamine, 118 Tetrahydrocarvoxime, 289
dimethylamine, 117 Tetrahydrocarvyl acetate, 214, 293
ethylamine, 118 amine=Carvomenthylamine, 111, 290,
nitroso-derivative of, 118 863
methylamine, 117 bromide, 293
piperidide, 118 chloride, 293
nitrosite, 114 phenylurethane, 293
oxide oxime, 115 Tetrahydrochlorocymene, 293
isomeride of, 115 Tetrahydrocymene, 18
Terpineol, 254 Tetrahydrocymene = Carvomenthene, 124
isomeric, m.p. 32° to 33°, 273 Tetrahydrocymene = Menthene, 126
nitrolpiperidide, 274 Tetrahydroeucarvone, 223, 293
itrosochloride, 274 oxime, 293
phenylurethane, 274 oxidation of, 294
isomeric, m.p. 69° to 70° = 44)-Ter- semicarbazone, 293
pen-1-ol, 269 Tetrahydrofenchene, 131, 159
** Terpineol,”’ li uid, 254, 257, 258 bromo-derivative of, 131
dibromide, 257 Tetrahydroisocamphor, 252
Terpineols, 254, 266, 267 phenylurethane, 252
Terpineol, solid, m.p. 35°, 255, 258 Tetrahydropinene, 39, 130
dibromide, 198, 260 Tetraterebentene, 435
keto-lactone from, 263 dihydrobromide, 435
nitrolamines, 262 dihydrochloride, 435
anilide, 262 hydrochloride, 435
piperidide, 262, 266 Tetraterpenes, 435
nitrosate, 262 Thujaketone, 232
nitrosochloride, 261, 266 oxime, 232
oxidation of, 262 a-Thujaketonic acid, 229

relation to other terpene | g-Thujaketonic acid, 229
derivatives, table of, 268 | a-Thujaketoximic acid, 157, 231

Terpines, 319 hydrobromide, 231
Terpinolene, 105 hydrochloride, 231
dibromide, 107 p-Thujaketoximie acid, 157, 231
tetrabromide, 107 Thujamenthol, 236, 295
Terpiny] acetate, 259 Thujamenthone, 236, 294
formate, 258, 259, 266 eto-lactone from, 295
methyl ether, 259 oxidation of, 295
phenylurethane, 259, 266 oxime, 294
Tertiary carvomenthol, 316 semicarbazone, 294
carvomenthylamine, 373 Thujene, 118, 205, 235, 360, 361, 362
derivatives of, 374 Thujolacetic acid, 227
carvomenthy! bromide, 317, 373 ethyl ester, 227
earvomenthyl iodide, 316, 373 Thujone, 157, 205, 224
menthol, 317 acid sodium sulphite, 225
menthylamine, 374 ethoxyl]-derivative of, 227
derivatives of, 374 methoxyl-derivative of, 226
menthyl acetate, 317 oxidation of, 229, 233
bromide, 317, 374 oxime, 227
iodide, 317, 374 isomeride of, 227 _
methyl] ether, 260, 317 oxymethylene derivative of, 229
phenylthiocarbamide, 374 pernitroso-derivative of, 228
Tetrabromide, CioHiusBra, 93 semicarbazone, 228
Tetrabromogeranyl! phthalate, 393 tribromide, 226 _
Tetrahydric alcohol, C1oH 2004, 363 acetyl derivative of, 227
Tetrahydrocarveol, 111, 214, 217, 237, 291 | Thujylamine, 227, 360, 362
acetate, 214, 293 carbamate, 360
bromide and chloride, 293 hydrochloride, 360 ;
derivatives of, 293 isomeric, 361 _
Tetrahydrocarvone, 111, 287 hydrochloride, 361
acid sodium sulphite, 288 nitrate, 361
bisnitrosylic acid, 288 henylcarbamide, 361
oxime, 288 biiag alcohol, 205, 227, 234
condensation-product with benzalde- chloride, 235

hyde, 290 Thujylimine nitrate, 228

INDEX.

Thujyl phenylearbamide, 361
isomeric, 361
pwimethy! ammonium hydroxide, 361
iodide, 361
oquinone, 189
Gluie acid, 215

hydrobromides, 61, 62
_ Tribromofenchone, 159
heptanonol, 406
_ _ methyl hexyl earbinol, 406
1, 2, 4-Tribromoterpane, 198, 260
ext: 2, 8-Tribromoterpane, 198
ey oe 8-Tribromoterpane, see monobro-
oon dihy robromide, 92, 198
Trieye ene, 46, 121
ichloride, 41, 46
hydrochloride, 121
eect, 64
err ineine, 31, 370 Shia
'rimet ylamine pyrrolidine, 31
Hencag! terebentyl ammonium chlor-

$ iodide, 340
: Parton mone, 208, 214, 234,
262, 266

457 4

Papeyheselsy deocymene, derivatives of,

1, 2, 8-Trioxymenthane = 1, 2, 8-Trioxy-
terpane, 262, 266
1, 2, 8-Trioxyterpane, 221, 262
1 4, 8-Trioxyterpane, 273, 334
Triterpenes, 432
Vv

Valerian camphor, 142
x-Valerolactone-y-dcetic acid, 243
Valerylene, polymerization of, 431
Vestrylamine, 359

hydrochloride, 103, 859

¥

Yilang-ylang essence = Oil of ylang-ylang
381, 388, 415

Zingiberene, 429
dihydrochloride, 429
nitrosate, 430
nitrosite, 429
nitrosochloride, 429
tetrabromide, 430

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Author ......

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Chemistry..of. the terpenes...

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