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Full text of "The chemistry of the terpenes"

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THE CHEMISTRY OF THE TERPENES 



HEUSLEK-POND. 



e/ 



( <$* 

^SV THE CHEMISTRY 




OF 



THE TEKPENES 



BY 
F. HEUSLER, PH.D., 

PRIVATDOCENT OF CHEMISTRY IN THE UNIVERSITY AT BONN. 



AUTHORIZED TRANSLATION 

BY 

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

ASSISTANT PROFESSOR IN THE PENNSYLVANIA STATE COLLEGE. 



CAREFULLY REVISED, ENLARGED AND CORRECTED. 




PHILADELPHIA : 

P. BLAKISTON'S SON & CO. 

1012 WALNUT STREET. 

1902 




Copyright, 1902, by 
P. BLAKISTON'S SON & Co. 



\y 



TO 

GEHEIMRATH PROFESSOR OTTO WALLACE 

THIS VOLUME IS 

GRATEFULLY DEDICATED 

BY THE AUTHOR AND TRANSLATOR. 



PREFACE TO THE AMERICAN EDITION. 



THE 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 



viii PEEFACE. 

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. POND. 

STATE COLLEGE, 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 " Handworterbuch " 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. HEUSLER. 



IX 



TABLE OF CONTENTS. 



PAGE. 

INTRODUCTION 17 



SPECIAL PART. 

HEMITEBPENES, CsHg ............................................................ 31 

Isoprene, C^Hs ......................................................... 31 

TERPENES Proper, CioHi 6 ....................................................... 34 

1. Pinene ............................................................... 34 

2. Camphene .......................................................... 56 

3. Fenchene ........................................................... 66 

4a. Limonene ......................................................... 71 

4b. Dipentene ......................................................... 85 

5. Sylvestrene ......................................................... 99 

6. Carvestrene ........................................................ 103 

7. Terpinolene ....................................................... 105 

8. Phellandrene ...................................................... 108 

9. Terpinene ........................................................... 112 

10. Thujene (Tanacetene) ........................................... 118 

11. Terpene from the Resin of Indian Hemp ..... , ........... 119 

12. Synthetical Terpene ............................................ 120 

13. Fenchelene ......................................................... 120 

14. Euterpene ......................................................... 120 

15. Tricyclene ........................................................ 121 

16. Bornylene ........................................................... 121 

17. Sabinene ............................................................ 121 



HYDROCARBONS, CioHig ......................................................... 123 

1. Dihy drocamphene .................. ............................. 123 

2. Isodihydrocamphene ............................................ 124 

3. Carvomenthene .................................................. 124 

4. Menthene ............................................. . ............. 126 

HYDROCARBONS, CioH 20 ........................................................ 130 



OXIDIZED COMPOUNDS RELATED TO THE TERPENES, CioHie ......... 133 

I. SUBSTANCES WHICH CAN NOT BE REGARDED AS DERIVA- 
TIVES OF -THE HYDROCYMENEB. (ANALOGUES OF 
PINENE, CAMPHENE, FENCHENE ) ........................... 133 

xi 



x ii TABLE OF CONTENTS. 

PAGE. 

1. Camphor, Ci Hi 6 133 

2. Borneol, Ci Hi 7 OH 141 

3. Isoborneol, CioHnOH 146 

4. Camphene Glycol, C 10 H 16 (OH) 2 151 

5. Camphol Alcohol, CioHigOH 152 

6. Camphenone, CioH^O 152 

7. Pinocamphone, CioHieO 154 

8. Pinocampheol, CioHnOH 155 

9. Fenchone, CioHi 6 155 

10. Fenchyl Alcohol, CioHnOH 170 

11. Isofenchyl Alcohol, CioHnOH 174 

12. Fencholenyl Alcohol and Isofencholenyl Alcohol, 

CioHnOH 176 

13. Fenchenole, Ci Hi 8 177 

II. COMPOUNDS WHICH MAY BE REGARDED AS DERIVATIVES 

OF THE HYDROCYMENES 178 

A. Substances Containing two Ethylene Linkages. Ketones, 

Ci Hi 4 O, and Alcohols, Ci Hi 5 OH 178 

1. Carvone, CioHi 4 178 

2. Carveol Methyl Ether, Ci Hi 5 OCH 3 197 

3. Eucarvone, CioHuO 198 

4. Pinocarvone, CioH^O 201 

5. Pinocarveol, CioHnOH 202 

6. Pinenol, Ci Hi 5 OH 202 

7. Pinenone, CioH^O 203 

8. Limonenol, CioHi 5 OH 203 

9. Limonenone, CioH^O 204 

10. Sabinol, Ci Hi 5 OH 204 

B. Substances Containing one Ethylene Linkage. Ketones, 

CioHi 6 O, Alcohols, Ci Hi 7 OH, and Oxides, Ci Hi 6 O... 206 

1. Dihydrocarvone, CioHi 6 206 

2. Dihydrocarveol, CioHnOH 212 

3. Carvenone, CioHieO 216 

4. Carone, Ci Hi 6 O 219 

5. Dihydroeucarvone, Ci Hi 6 O 223 

6. Dihydroeucarveol, CioHnOH 224 

7. Thujone (Tanacetone), Ci Hi 6 224 

8. Thujyl Alcohol (Tanacetyl Alcohol), CioHnOH 234 

9. Isothujone, Ci Hi 6 235 

10. Carvotanacetone, Ci Hi 6 236 

11. Pulegone, Ci Hi 6 O ... 237 

12. Isopulegol, CioHnOH, and Isopulegone, Ci Hi 6 247 






TABLE OF CONTENTS. xiii 

PAGE. 

13. Menthenone, CioHieO 250 

14. Isocamphor, CioHieO 251 

15. Pinolone, Ci Hi 6 O, and Piuolol, CioHnOH 253 

16. As-Menthene-2-one, Ci Hi 6 253 

17. Terpineol, Ci Hi 7 OH , 254 

18. Isomeric Terpineol (A 4(8) -Terpen-l-ol), melting at 69 

to 70, CioHnOH 269 

19. Isomeric Terpineol, CioHnOH, melting at 32 to 33. 273 

20. Pinole, Ci Hi 6 274 

21. Eudesmole, CioH 16 285 

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

Alcohols, CioHigOH and C 10 Hi 8 (OH) 2 , Oxides, Ci Hi 8 O, 

etc 287 

1. Tetrahydrocarvone (Carvomenthone), CioHigO 287 

2. Tetrahydrocarveol (Carvomenthol), CioHigOH 291 

3. Tetrahydroeucarvone, CioHi 8 O 293 

4. Thujamenthone, CioHigO 294 

5. Thujamenthol, CioHigOH 295 

6. Menthone, Ci Hi 8 295 

7. Menthol, CioHigOH 308 

8. Tertiary Carvomenthol, CioHigOH 316 

9. Tertiary Menthol, CioHigOH 317 

10. Terpine, Ci Hi 8 (OH) 2 318 

11. Menthene Glycol, Ci Hi 8 (OH) 2 323 

12. Cineole, Ci Hi 8 323 

13. Terpan-1, 4, 8-triol, Ci Hi 7 (OH) 3 334 

14. Trioxyhexahydrocymene, CioHi7(OH)3 334 

15. Pinole Hydrate, Ci Hi 7 O-(OH) 334 

16. Limonetrol, Ci Hi 6 (OH) 4 334 

17. Pinole Glycols, Ci Hi 6 O(OH) 2 334 

AMIDO-DERIVATIVES OF THE TERPENES 336 

I. BASES WHICH CAN NOT BE EEGARDED AS DERIVATIVES 
OF THE HYDROCYMENES. (ANALOGUES OF PINENE, 
CAMPHENE, FENCHENE, AND OF CAMPHOLENIC ACID 
AND FENCHOLENIC ACID) 336 

1. Pinylamine, Ci Hi5NH 2 336 

2. Amidoterebentene, CioHi5NH 2 338 

3. Bornylamines, Ci Hi 7 NH 2 340 

4. Camphylamines, C 9 Hi 5 CH 2 NH 2 346 

5. Fenchylamine, Ci Hi 7 NH 2 347 

6. Fencholenamine, C 9 Hi 5 CH 2 NH 2 351 

7. Campholamine, C 9 Hi 7 CH 2 NH 2 353 



x i v TABLE OF CONTENTS. 

PAGE. 
II. BASES WHICH MAY BE REGARDED AS DERIVATIVES OF 

THE HYDROCYMENES 354 

A. Amines, CioHi5NH 2 , Containing two Ethylene Linkages 354 

1. Carvylamines, CioHi5NH2 354 

B. Amines, CioHi 7 NH 2 , Containing one Ethylene Linkage 356 

1. Dihydrocarvylamine, CioHiyNH^ 356 

2. Carylamine, Ci Hi 7 NH 2 358 

3. Vestrylamine, Ci H 17 NH 2 359 

4. Dihydroeucarvylamine, CioHi7NH2 359 

5. Thujylamine (Tanacetylamine), CioHi7NH2 360 

6. Isothujylamine, Ci Hi 7 NH 2 362 

7. Pulegylamine, Ci Hi 7 NH 2 362 

C. Amines, CioHigNH 2 , Without an Ethylene Linkage 364 

1. Carvomenthylamine (Tetrahydrocarvylamine), CioHig- 

NH 2 364 

2. Menthylamine, Ci Hi 9 NH 2 365 

3. Tertiary Carvomenthylamine, CioHi 9 NH 2 373 

4. Tertiary Menthylamine, CioHi 9 NH 2 374 

AMIDO-DERIVATIVES OF PHELLANDRENE 374 

1. Amidophellandrene, CioHi5NH 2 374 

2. Diamidophellandrene, CioHi6(NH 2 ) 2 375 

OLEFINIC MEMBERS OF THE TERPENE SERIES 377 

A. Hydrocarbons 377 

1. Myrcene, Ci Hi 6 377 

2. Anhydrogeraniol, CioHie 379 

3. Olefinic Terpenes in Oil of Hop and Oil of Origanum. 380 

4. Linalolene, CioHig 380 

5. Hydrocarbon ,^CioHig, obtained from Menthonylamine, 380 

B. Oxygenated Compounds 381 

(a) Alcohols 381 

1. Linalool, Ci Hi 7 OH 381 

2. Geraniol, Ci Hi 7 OH 387 

3. Menthocitronellol, Ci Hi 9 OH '. 393 

4. Citronellol, Ci Hi 9 OH 394 

(b) Aldehydes 396 

1. Geranial (Citral), Ci Hi 6 396 

2. Menthocitronellal, Ci Hi 8 409 

3. Citronellal, Ci Hi 8 409 

C. Amines 413 

1. Menthonylamine, CioH 19 NH 2 413 

SESQUITERPENES AND POLYTERPENES 414 

Seaquiterpenes, Ci 5 H 24 , and Sesquiterpene Alcohols, CisH^OH... 414 






TABLE OF CONTENTS. XV 

PAGE. 

1. Cadinene, Ci5H24 414 

2. Caryophyllene, Ci5H24 417 

3. Clovene, CisH^ 421 

4. Humulene, Ci5H24 421 

5. Cedrene, CisH^, and Cedrol ("Cedar Camphor"), 

Ci 5 H 25 OH 423 

6. Cubeb Camphor, Ci 5 H 25 OH 424 

7. Ledum Camphor, CisH^sOH, and Ledene, Ci5H24 425 

8. Patchouly Alcohol, CisH^OH, and Patchoulene, 

Ci 5 H 24 425 

9. Guaiol, Ci 5 H 25 OH 426 

10. Santalol, Ci 5 H 25 OH, and Santalene, Ci 5 H 24 426 

11. Galipol, Ci 5 H 25 OH, and Galipene, CisH^ 428 

12. Caparrapiol, CisH^OH, and Caparrapene, CisH^ 428 

13. Zingiberene, CisH^ 429 

14. Olefinic sesquiterpene, CisH^, from the oil of citro- 

nella 430 

Diterpenes, C2oH3 2 431 

Triterpenes, C3oH4g 432 

1. a- and /3-Amyrin, C3oH 49 OH 432 

Tetraterpenes, C4oH&4 435 



THE TERPENES. 



THOSE hydrocarbons which have the empirical constitution, 
C 5 H g , are termed terpenes. Four main classes are recognized : 

Hemiterpenes, C 5 H 8 , 
Terpenes proper, C ]0 H I6 , 
Sesquiterpenes, C 15 H 24 , 
Polyterpenes, (C 5 H 8 ) X . 

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 ]8 O, and the alcohol 
corresponding to this ketone, menthol, C 10 H 19 OH. Two com- 
pounds, carvomenthone, C 10 H 18 O, and carvomenthol (tetrahydro- 
carveol), C 10 H 19 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 carvo- 
menthol, hydrocarbons, C 10 H 18 , 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. 



19 





Hexahydrocymene 
(Terpane, Men thane). 



H S C CH S 

Menthone 

( /3-Ketohexahydrocymene, 
Terpan-3-one, Menthan-3-one). 




H S C CH 3 
Menthol 

( /3-Oxyhexahydrocymene, 
Terpan-3-ol, Menthan-3-ol). 




Menthene 

( A 3 -Tetrahydrocymene, 
A'-Terpene, A s -Menthene). 




H 3 C CH 8 

Carvomenthone 
( a-Ketohexahydrocymene, 
Terpan-2-one, Menthan-2-one). 




H S C CH S 
Carvomenthol 
( a-Oxyhexahy drocymene, 
Terpan-2-ol, Menthan-2-ol). 




H 3 C CH S 
Carvomenthene 
( Ai-Tetrahydrocymene, 
A'-Terpene, A '-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. 





H 3 (5 CH, H,C CH 3 

Tertiary Menthol. Tertiary Carvomenthol. 

Theory also clearly allows other isomeric tetrahydrocyraenes 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, thujarnenthone, 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, C 10 H 18 , 
to be replaced by a carbonyl group, we arrive at the ketones, 
C 10 H 16 O, which contain one double linkage, and are to be regarded 
as derivatives of tetrahydrocymene. By reduction of these ke- 
tones, C 10 H 16 O, secondary alcohols, C, H 17 OH, are formed which 
may be transformed into terpenes, C 10 H 16 , 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 10 H 16 , 
by the addition of the elements of water, is also possible. 

Ketones, C 10 H 16 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 10 H 17 OH, just referred to, 
tertiary alcohols, C 10 H 17 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 : 




H. 



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




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 10 H ir NH 2 , which have been prepared 
by various methods from the ketones, C 10 H 16 O, or the alcohols, 
C 10 H 17 OH, are to be considered with the latter. 

If a molecule of water is withdrawn from the alcohols, C 10 H 17 OH, 
or ammonia from the bases, C 10 H 17 NH 2 , a class of terpenes, C 10 H 16 , 



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. 




H 3 C CH 8 
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 10 H U 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 10 H 14 O, which are derived from 
menthone, we are as yet unacquainted. The known ketones, 

C 10 H 14> 



INTRODUCTION. 23 

Carvone, 

Eucarvone, 

Pinocarvone, 

are all derivatives of carvomenthone, and this substance 
owes its name to precisely this relation which it bears to 
carvone. An alcohol, C 10 H, 5 OH, corresponding to carvone, is 
known only in its methyl ether, but, on the other hand, an 
alcohol, C 10 H 15 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 the" 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 1 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 10 H 16 , hitherto known 
as terpenes, as twpadienes. 

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 : 




H 3 

A-l, 4(8)-Terpadiene. 

According to Baeyer, the ketones, C 10 H 18 O, are termed ter- 
panones, the alcohols, C 10 H 19 OH, terpanols, with an index figure to 
designate the carbon atom to which the oxygen is attached. The 
ketones, C 10 H 16 O, and the alcohols, C 10 H 17 OH, Baeyer designates 
as terpenones and lerpenols. 

'Baeyer, 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 10 H 18 . In order to avoid this difficulty, but, at 
the same time, to preserve the unquestionable advantage of Baeyer's 
system of nomenclature, Wagner l has suggested that hexahydro- 
cymene be called menthane. The hydrocarbons, C 10 H 18 , retain the 
name menthene, which has already been employed for one member 
of this group, while the dihydrocymenes, C 10 H 16 , may be called 
menthadienes, 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, 2 men- 
thone is often designated as ft-, carvomenthone as a-keto- 
hexahydrocymene, and, correspondingly, all unsaturated ke- 
tones which yield menthone by hydration are termed /?-, 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 10 H lg . If it be imagined, in a manner similar to that above, that 
one methylene group in these hydrocarbons, C 10 H 18 , be replaced 
by a carbonyl group, the ketones, C 10 H 16 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, 3 Bredt 4 ) : 

'Wagner, Ber., 27, 1636. 

sWallach, Ann. Chem., 277, 105. 

3 Kannonikow, Journ. Russ. Phys. Chem. Soc., 1, 434. 

<Bredt, Ann. Chem., 226, 261. 



INTRODUCTION. 



25 




H 



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




During the course of further investigations, however, these for- 
mulas have proved untenable, and Bredt 2 has proposed the fol- 
lowing formulas for camphor, pinene and camphene : 




CH 




!HOH 



Camphene. 



Pinene. 



Bredt's camphor formula interprets the conduct of this com- 
pound especially well in the formation of trimethylsuccinic acid 



i Wallach, Ber., 24, 1545. 
2 Bredt, Ber., 26, 3047. 



26 THE TEKPENES. 

from camphoronic acid resulting from the oxidation of camphor. 
The behavior of piuene 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 3 ) 2 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, C=CH 




+2H,0= H 2 C C(OH) CH, 
}(OH): CH, 



CH S 



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. 1 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 10 H 16 , 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 10 H 16 , 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 10 H 18 O, 
pinole hydrate, C 1() H 17 O-OH, and fenchenole, C 10 H 18 O. 

1 Wagner, Ber., 27, 2270; Tieinann 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 10 H 16 , results from heating isoprene to a high temperature, 
and which Wallach l 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 
igoprene, which had not been prepared by synthetical methods, 
was not known. 

After Wallach 2 in the year 1890 had demonstrated that cer- 
tain unsaturated aliphatic ketones (methyl hexylene ketone, 
C 8 H 14 O, and methyl heptylene ketone, C 9 H 16 O), could easily be 
converted, by the elimination of water, into lower homologues of 
the terpenes (dihydro-meta-xylene, C 8 H ]2 , and dihydro-pseudo- 
cumene, C 9 H 14 ), Bertram and Walbaum 3 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 10 H 17 OH, which is found in 
nature. 

The complete synthesis of a dihydrocymene, C 10 H 16 , was accom- 
plished in the year 1893 by Baeyer, 4 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 10 H )6 O, has been synthetically prepared by Knoe- 
venagel. 5 This compound, to which Knoevenagel ascribes the 
formula 

CH 

o-^ 



H 2 CH, 



CH 



H 3 C CH 3 
is derived from isobutylidene diaceto-acetic ester, 

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

'Wallach, Ann. Chem., 258, 338; 272, 120; Ber., 24, 1573. 

8 Bertram and Walbaum, Journ. pr. Chem., N. F., ^5, 601. 

Baeyer, Ber., 26, 233. 

5 Knoevenagel, Ber., 26, 1085; Ann. Chem., 281, 44. 



28 THE TERPENES. 



^,, 

/ CH< COC H 3 
(CH 3 ) 2 CH-CH 

\/-ITT^^ U ^ M3 

CH<COOC 2 H 6 

Although all the above-mentioned terpenes, C 10 H 16 , as well as 
their related oxidized compounds, possess a ring formation of the 
carbon atoms, nevertheless, another series of hydrocarbons, C 10 H 16 , 
and several oxygen-containing compounds, C 10 H 16 O, C ]0 H J8 O, and 
C 10 H 20 O, 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 10 H 16 , are designated as olefinic terpenes, according to a 
proposition of Semmler, 1 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 10 H 17 OH, but exist as well already formed in nature. It should 
further be mentioned that hydrocarbons, C 10 H 18 , 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 10 H 17 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 lft H 16 O, which also occurs in nature. Accord- 
ing to Tiemann and Semmler, geranial is probably a dimethyl-2-6 
octdien-2-6-al-8 : 



CH S 0=CH CH 2 2 - 

CH 3 CH 



3 3 



Citronellal, C 10 H 18 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 2 ). According to Tiemann and Semmler, this reaction is 
preceded by a transposition of the double linkage : 

Semmler, Ber., 2> t , 682. 

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



INTRODUCTION. 29 




H 3 C CH 3 H 3 C CH, 

Geranial. Cymene. 

More important, however, is the fact that, according to Bertram 
and Walbaum, 1 two well known terpenes, dipentene and terpinene, 
may be obtained by the removal of water from linalool or geraniol, 
C 10 H 17 OH. In a similar manner, Tiemann and Semmler 2 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 3 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 10 H 18 NOH, yields menthonitrile, C 9 H 17 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 10 H 19 NH 2 . This base, 
which is isomeric with the cyclic compound menthylamine, yields, 
by the action of nitrous acid, menthonyl alcohol (menthocdtronelloF), 
Cj ,H 19 OH, which is a primary olefinic alcohol and is converted 
by oxidation into an aldehyde (menthocitronellal), C 10 H 18 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. 

Bertram and Walbaum, Journ. pr. Chem., N. F., 45, 590. 
2 Tiemann and Semmler, Ber., 26, 2708. 
"Wallach, 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 1 in the year 1891. 

Although the investigations of Wallach have made possible a 
systematic classification of the terpenes proper, C 10 H 16 , 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 2 has made efforts to compile at least a classification 
for the sesquiterpenes, C 15 H 24 . Still, this work has not been in 
any degree as successful as in the analogous case of the terpenes, 
C 10 H 16 . Several alcohols, C 15 H 25 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 have 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 present all 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. 

i Wallach, Ber., 24, 1525. 

*Wallach, Ann. Chem., 271, 285 and 297. 



SPECIAL PART. 

Hemiterpenes, C 6 H 8 . 

For the numerous isomeric hydrocarbons, C 5 H 8 , 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 5 H 8 . 

If the oil obtained by the dry distillation of caoutchouc or 
guttapercha be submitted to a fractional distillation, a distillate 
is obtained which consists of isoprene. Williams, 1 Bouchardat, 2 
Tilden, 3 Wallach, 4 Euler 5 and Mokiewsky 6 have published in- 
vestigations concerning this hydrocarbon. 

Euler 5 prepared isoprene by the following method. 3-Methyl- 
pyrrolidine, C 5 H 10 NH, on treating with methyl iodide, yields a 
compound, which, when distilled with potash, yields 2, 3, 5-trimeth- 
ylpyrrolidine, C 7 H 14 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, 

CH 2 = C(CH 3 ) CH = CH 2 . 

Pure isoprene 6 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 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. 

1 Williams, Journ., 1860, 495. 

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

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

*Wallach, Ann. Chem., 227, 295. 

5 Euler, Ber., 30, 1989. 

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

31 



32 THE TEBPENES. 

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

Isoprene hydrocbloride, C 5 H 8 -HC1, 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. 
3 Isoprene dihydrocbloride, C 5 H 8 -2HC1, boils at 143 to 145, and 
has the specific gravity 1.079 at 0. 

Isoprene hydrobromide, C 5 H 8 HBr, boils at 104 to 108, and 
at has the specific gravity 1.192. 

According to Mokiewsky, 1 the action of an acetic acid solution 
of hydrogen bromide on isoprene gives a hydrobromide, C 5 H 9 Br, 
which boils at 66 to 67, and has the specific gravity 1.3075 at 
and 1.2819 at 20. On treating this bromide with alcoholic 
potash, an alcohol, C 5 ET 10 O, is formed; it boils at 97 to 99, and 
has the specific gravity 0.8417 at and 0.8242 at 20. 

Isoprene dihydrobromide, C 5 H g 2HBr, has the specific gravity 
1.623, and boils at 175 to 180. 

Isoprene dibromide, C 5 H 8 Br 2 , 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 5 H 8 Br 2 (OH) 2 , 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 5 H g Br 4 , was first prepared by Tilden. It 
is an oil which decomposes by distillation, but, according to Wal- 
lach, 2 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 5 H 8 C1 2 (OH) 2 , is formed, together with 
the chlorhydrin of trimethylene glycol, C 5 H U C1O, 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- 

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



ISOPRENE DIBROMHYDRIN. 33 

cohol, ether or benzene, melts at 82.5, and, when heated with 
water at 120, forms a compound, C 5 H 9 C1-OH, which melts at 
72.5 to 73. The compound, C 5 H U C1O, boils at 141, and has 
a specific gravity 1.0562 at 0. 

Isoprene dibromhydrin, C 5 H g Br 2 (OH) 2 , is formed by treating iso- 
prene with hypobromous acid ; it crystallizes in hexagonal plates, 
and melts at 86. It is more readily prepared than the corre- 
sponding chlorine derivative. 



TERPENES PROPER, C 10 H 16 . 
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 1 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 2 in the pine needle oils from Abies alba, Picea excdsa, 
Pinus montana, and Pinus silvestris L., 3 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, 4 oil of Siberian pine needles, 6 oil 
of pine-resin, 6 oil of juniper berries, 7 oil of eucalyptus (E. globu- 
lus), 9 oil of mace, 7 oil of sage, 10 oil of lemon, 7 oil of basil, 8 
oil of laurel berries and laurel leaves, 10 oil of olibanum, 10 valerian 

Wallach, Ann. Chem., 227, 282; 230, 245; 252, 94; 258, 340. 

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

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

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

6 Flawitzky, 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. 

l Wallach, Ann. Chem., 252, 94. 

34 



PINENE. 35 

oil, bay oil, 1 camphor oil, coriander oil, fennel oil, oil of massoy 
bark, 2 oil of myrtle, 3 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, 4 and oil of valerian (Japan- 
ese). 5 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 6 recognized this hydrocarbon in the dis- 
tillation products of copal resin, olibanum and colophonium. 
Commercial resin oil also contains pinene as shown by Renard, 7 
who isolated from this product a levorotatory hydrocarbon hav- 
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, 8 who recognized it in the prod- 
ucts of distillation of pine roots and trunks of the Scotch fir. 

PBEPAEATION. 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 ; 9 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 10 H 16 NOC1 + 2C 6 H 5 NH 2 = H 3 O + HC1 + C,H B N:NC 6 H 4 NH 2 + C 10 H 16 . 

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

'Mittmann, Arch. Pharm., 227, 529. 
nVallach, Ann. Chem., 258, 340; Arch. Pharm., 229, 1. 
sjahns, Arch. Pharm., 227, 174. 
1 Power and Kleber, Pharm. Review, 1896. 
s Bertram and Gildemeister, Arch. Pharm., 228, 483. 
'Wallach and Rheindorf, Ann. Chem., 271, 308. 
'Renard, Ann. Chim. Phys. [6], 1, 223. 

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

"Wailach, 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 
n^ = 1.46553. 

According to their sources, the optically active modifications 
have a specific gravity of 0.8587 to 0.8600, and a rotatory 
power, []=+ 32 to [] = - 43.4 . 1 

The spectrometric behavior of levo-pinene has been closely ex- 
amined by Briihl. 2 

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 5 H 8 , benzene, toluene, meta- 
xylene, cymene, naphthalene, anthracene, methylanthracene, 
phenanthrene, and terpilene (terpinene) are formed (G. Schultz 3 ). 
Pinene absorbs oxygen from the air forming acetic acid, hydrogen 
peroxide, 4 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 5 
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 5 H 6 O 2 , di- 
methyl fumaric acid, C 6 H 8 O 4 , oxalic acid, para-toluic acid, C 8 H 8 O 2 , 
terephthalic acid, C 8 H 6 O 4 , terebic acid, C 7 H 10 O 4 , terechrysiuic 

^annonikow, Ber., 1881, 1697. 

'Briihl, Ber., 25, 153. 

3 G. Schultz, Ber., 1877, 114; compare Tilden, Journ. Chem. Soc., 45, 411. 

Kingzett, Jahresb. Chem., 1876, 402. 

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



PINENE. 37 

acid, C 6 H 8 O 5 , and nitrobenzene. 1 Chromic acid solution oxidizes 
turpentine oil into acetic acid, terebic acid, terperlylic acid, 
C 8 H 12 O 4 , and a little terephthalic acid. 1 

Reducing agents, such as phosphonium iodide at 300 , 2 hydriodic 
acid and red phosphorus at 275 , 3 and a hydriodic acid solution 
of specific gravity 2.02 at 280 , 4 convert turpentine oil into the 
hydrocarbons, C 10 H 20 or C 10 H 18 (b. p. 165), C 10 H 20 (b. p. 170 to 
175), C 10 H 22 (b. p. 155 to 162), and C 5 H 12 (b. p. 40). When 
heated with iodine at 230 to 250, meta-xylene, a little para- 
xylene and cyraene, pseudocumene, raesitylene, a hydrocarbon, 
C U H 16 (b. p. 189 to 193), durene and polyterpenes, (C ie H 16 ) n , 
are formed. 

To return to the consideration 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. 5 

Dilute nitric 6 or sulphuric acid converts pinene into dipentene 
and terpine hydrate. 

According to Wallach, the terpenes, terpinolene and terpinene, 7 
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, 8 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 

'Roser, Ber., 1882, 293; Fittig and Kraft, Ann. Chem., 208, 74; compare 
publications of Schryver, Journ. Chem. Soc., 1893 (I), 1327; Ber., 27, 
133 Ref. 

"Baeyer, Ann. Chem., 155, 276. 

S 0rlow, Journ. Russ. Phys. Chem. Soc., 15, 44; Ber., 16, 799. 

*Berthelot, Journ., 1869, 332. 

sWallach, Ann. Chem., 227, 282. 

sHempel, Ann. Chem., 180, 73. 

> Wallach, Ann. Chem., 227, 282; 230, 262. 

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



38 THE TERRENES. 

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

Pinene picrate, C 10 H 16 C 6 H 2 (NO 2 ) 3 OH, is prepared, according 
to Lextreit, 1 by heating pinene with picric acid at 150 ; it forms 
crystals, 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 2 ). 

Pinene bydrochloride, 3 C 10 H 16 HC1 (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 4 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, 5 which have been confirmed by 
Wallach and Conrady ; that prepared from levo-pinene is levo- 
rotatory, [a] D = 30.687 and 26.3. 

According to more recent investigations by J. H. Long, 6 pinene 
hydrochloride melts at 131 and not at 125, and the different 
values (from to -f 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 
1-pinene, and that the hydrochloride from dextro-pinene has a 
slightly lower rotatory power than d-pinene. 

J Lextreit, Compt. rend., 102, 555; Ber., 19, 237, Ref. 

2 Tilden and Forster, Journ. Chem. Soc., 1893 (1), 1388; Ber., 27, 136, Ref. 

8 Wallach, Ann. Chem., 239, 4; compare J. Kondakovv, Chem. Zeit., 25 
(1901), 609. 

'Tilden, Ber., 12, 1131. 

5 Pesci, Gazz. Chim., 1888, 223; Wallach and Conrady, Ann. Chem., 252, 
156. 

6 John H. Long, Journ. Amer. Chem. Soc., 21, 637. 



V 

PINENE HYDROBROMIDE. 39 

Camphene l 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 2 regards the hydrochloride as more closely related 
to camphene than to pinene, and, since it may be converted into 
dihydrocamphene, 3 C 10 H 18 (which he calls camphydrene), by the 
action of sodium and alcohol, he introduces the term cAforocaw- 
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 4 
obtained ketopinic acid, C 10 H ]4 O 3 , 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 10 H 16 O 4 , camphopyric or cam- 
phoic acid, and other acids. 5 

According to Wagner, 6 pinene hydrochloride is the true chlo- 
ride of borneol ; this view is also supported by Semmler. 3 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 bornyl acetate. 

Tetrahydropinene, C^H^, was obtained by Wallach and Berk- 
enheim 7 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 10 H 16 -HBr, was first obtained by De- 
ville. 8 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, 

1 Wallach, Ann. Chem., 252, 6. 
2 Armstrong, Journ. Chem. Soc., 69 (1896), 1398. 
'Semmler, Ber., 33, 774. 

4 Armstrong, Journ. Chem. Soc., 69 (1896), 1401. 
^Gardner and Cockburn, Journ. Chem. Soc., 73 (1898), 278. 
6 Wagner and Brickner, Ber., S2, 2302. 
'Wallach and Berkenheim, Ann. Chem., 268, 225. 

8 Deville, Ann. Chim. Phya., 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, 2 C 10 H 16 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 and 1.4635 at 
20 (Wagner 3 ). 

When prepared from a turpentine oil having a specific rotatory 
power, [a]j= 37 50', and washed with aqueous caustic pot- 
ash, it had the rotatory power, [a]^ = 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] D = 
-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 3 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. 4 

When French turpentine oil, boiling at 155 to 156 and 
having the specific rotation, []# = 37 30', is treated with 
hypochlorous acid, and the resulting product is acted upon by 
potash, a mixture is obtained from which Wagner 5 has isolated 
the following compounds : ds^pinole oxide (Wallach's anhydride 
of pinole glycoT), C 10 H 16 O 2 , ds-sobrerytrite (menthane-1, 2, 6, 8- 
tdrot), C 10 H 20 O 4 , cis-pinole glycol-2-chlorhydrin, C 10 H 16 O-C1(OH), 
cis-menthane-1, -dichlor-6, 8-dlol, C 10 H 18 O 2 C1 2 , a chlorhydrin of 

Wallach, 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. 
sWagner and Ginzberg, Ber., 29, 886. 



PINENE NITROSOCHIXmiDE. 41 

unknown composition, nopinole gtycol, C 10 H 18 O 3 , 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 10 H 18 O 3 , 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, 1 C 10 H 16 C1 2 , which Wagner calls tricyclene dichloride, 
is produced; it melts at 165 to 168. 

Additive Compound of Formaldehyde and Pinene. 2 A compound, 
C U H 18 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 n H 18 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 10 H 15 OH. 

Pinene nitrosochloride, C, H 16 NOC1, was discovered by Tilden, 3 
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 4 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 

'Ginzberg and E. Wagner, Journ. RUBS. Chem. Soc., 30 (1898), 675. 
*0. Kriewitz, Ber., 32, 57. 

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

<GoMschmidt, 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 l considers it 
as a bisnitrosyl-derivative : 

C 10 H 16 C1-NA-C IO H 16 C1. 

Wallach 2 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., 3 it melts at 108). 
This compound and its derivatives are optically inactive. Baeyer 4 
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 10 H 16 .NOBr, is obtained by a similar 
process. It melts at 91 to 92 with decomposition (Wallach 5 ). 

* 
Pinene Nitrolamines. 

Pinene nitrolpropylamine 6 melts at 96. 
Pinene nitrolamylamine 6 melts at 105 to 106. 
Pinene nitrolallylamine 6 melts at 94. 

Pinene nitrolpiperidide 7 is formed when pinene nitrosochloride is 
dissolved in excess of an aqueous or alcoholic solution of pi peri - 

i Baeyer, Ber., 28, 648. 
'Wallach, Ann. Chem., 253, 251 ; 2^5, 251. 
3 Schimmel & Co., Semi-Annual Report, April, 1901, 11. 
Baeyer, Ber., 29, 3. 
Wallach, Ann. Chem., 253, 251. 
Wallach and Friistiick, Ann. Chem., 268, 216. 
TWallach, Ann. Chem., 2^5, 251. 



NITKOSOPINENE. 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. 

Finene nitrolbenzylamine 1 is obtained by the action of an alco- 
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, 

/NO 

CmHioS. 

6 \NHR 

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

/NHR RHN\ 

CTT / NO TT 

10 n 16\^^ T ^^-^^10 n 16 

"*~-Nj O 2 

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 10 H 15 NO, was obtained by Tilden 2 by the ac- 
tion of alcoholic potash on pinene nitrosochloride : 

C 10 H 16 NOC1 + KOH = C 10 H 15 NO + KC1 + H,O. 

Wallach and Lorentz 3 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 

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



44 THE TEBPENBS. 

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 recrystallization from 
ethyl acetate in the form of monoclinic crystals, 1 melting at 132. 

Nitrosopinene is optically inactive. Alcoholic hydrochloric 
acid converts it into carvoxime hydrochloride, 2 

As a result of their observations that nitrosopinene forms a 
sodium salt and a methyl ester, Goldschmidt and Zuerrer 3 classify 
this substance as an isonitroso-compound, C 10 H 14 =NOH, whilst 
Wallach 4 is inclined to regard it as having the constitution of a 
true nitroso-compound, C 10 H 15 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, 5 and the latter investiga- 
tor agrees with Goldschmidt in ascribing the isonitroso-structure 
to nitrosopinene. 

Meanwhile, however, Urban and Kremers 6 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, 5 carvacrol and hydroxylamine are formed 
by long-continued boiling of nitrosopinene with hydrochloric 
acid. Mead and Kremers 7 have also obtained the same result. 

When nitrosopinene is reduced with zinc dust and acetic acid, 
it yields a mixture of pinocamphone, C 10 H ]6 O, and pinylamine, 
C ]0 H 15 NH 2 . 8 Cymene is readily formed by the distillation of 
pinylamine hydrochloride. The same hydrocarbon is likewise 
obtained by the elimination of hydrogen bromide from pineue 
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- 

'Maskelyne, Jahresb. Chem., 1879, 396; Hintze, Ann. Chem., 252, 133. 

*Baeyer, Ber., 29, 3. 

'Goldschmidt and Zuerrer, Ber., 18, 2223. 

Wallach, Ber., 24, 1547. 

BBaeyer, Ber., 28, 646. 

6 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; SIS, 345. 



CRYSTALLIZED PINENE DIBROMEDE. 45 

lach's investigations l have shown that the various reactions are 
extremely complicated, a condition which the varying results of 
the investigations of Oppenheim, 2 Tilden 3 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. 4 

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 niono- 
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 10 H 18 , is obtained. 5 

Crystallized pinene dibromide, C 10 H 16 Br 2 , 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. 

'Wallaeh, Ann. Chem., 264, 1. 

2 0ppenheim, Ber., 5, 94 and 627. 

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

Stschukareff, Journ. pr. Chem., N. F., /,7, 191; see also Tilden, Journ. 
Chem. Soc., 69 (1896), 1009. 

Semmler, Ber., S3, 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, 1 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 2 also states that when pinene dibromide, melting at 
169 to 170, is treated with zinc 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 10 H 16 C1 2 . A compound, C 10 H 16 C1 2 , which 
is called tricyclene dichloride, 3 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. 

Two neutral reaction -products have been found by G. Wagner 4 
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 ]0 H 16 (OH) 2 . 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 

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

G. Wagner and Godlewski, Journ. Russ. Chem. Soc., 29 (1896), 121. 
sGinzberg and E. Wagner, Journ. Russ. Chem. Soc., SO (1898), 675. 
<G. Wagner, Ber., 21, 2270. 



PINONONIC ACID. 47 

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 10 H 18 O 2 , and is 
probably an a-glycolene. 

2. Koto-alcohol, C 10 H 16 O 2 . 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 10 H 16 O 2 . Wagner regards it as a keto-alcohol, 
although it does not react with carbanile ; it gives a crystalline 
oxime, C 10 H 16 (NOH) 2 , which melts at 130. 

When this compound is allowed to remain in contact with 
silver oxide, it is converted into pinononic acid? C 9 H 14 O 3 . 

A third neutral product of the oxidation of French turpentine 
oil is described by Wagner 1 as an aldehyde, which is oxidized by 
the air to an acid resembling camphenilic acid, C 10 H 16 O 3 , melt- 
ing at 171.5 to 172.5, which is obtained from camphene. 

Wagner l 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 9 H 14 O 3 . 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 add, C 8 H 12 O 4 , 
melting at 173 to 174, bromoform, and carbon tetrabromide 
(see norpic acid). 

2. An add 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 2 proposed 
the following formula for this terpene, 




-H, 

In the critical consideration of the constitutional formulas of 

'G. Wagner and Ertschikowsky, Ber., 29, 881. 
2G. 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 l 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 10 H 16 O 3 . 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 liters of 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. 2 

The liquid pinonic acid, which is to be regarded as a mixture 
of isomerides, 3 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, []/> = + 6, in a one decimeter tube, but 
this is increased to [a]i> = -f 13, when all of the a-pinonic 
acid is removed ; the latter acid has the specific rotatory power, 
[a]j,= -j- 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, 1 this liquid pinonic 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 2 melts at 207. 

It yields the keto-lactone, C 10 H lg O 3 (methoethylheptanonolide), 
melting at 63 to 65, when treated with acids, or when slowly 
distilled at atmospheric pressure. 2 

iTiemann and Semmler, Ber., 28, 1344 and 1778. 
J Tiemann and Semmler, Ber., 29, 529. 
F. 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, 1 C 10 H I6 O 3 , is a ketonic acid formed together with 
a-dioxydihydrocampholenic acid, by the oxidation of a-campho- 
lenic acid, C 10 H 16 O 2 (oxycamphor), boiling at 256. It is also 
produced by the dry distillation of a-dioxydihydrocampholenic 
acid, C 10 H lg O 4 , 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, 1^*]^ = 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 10 H 16 O 3 (meth- 
oethylheptanonolide), which in this case appears to be optically 
active. 

i-Pinonic acid, 2 C 10 H 16 O 3 , 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, 2 C 10 H 18 O 3 , 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 crys- 
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, 2 C 10 H 18 O 3 , is prepared from the liquid d-pinonic 
acid in the same manner as i-pinolic acid from the crystalline a- 
or i-pinonic acid. It crystallizes in well formed needles, melting 
at 114 to 115. In a thirty-three per cent, alcoholic solution it 
has a rotation 7 in a 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. 

iF. Tiemann, Ber., 29, 3006. 
F. Tiemann, Ber., SO, 409; 35, 2662. 
4 



50 THE TEKPENES. 

i-Pinocampholenic acid, 1 C 10 H 16 O 2 , 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, n^ == 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 ]0 H 16 O 2 , is prepared from the liquid 
d-pinonic acid or the 1-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 1-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). 

i-Pinodihydrocampliolenolactone, C 10 H 16 O 2 , 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, np = 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 m- and cis-rans-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 10 H 16 O 2 , to arrive at the optically 
active 1-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. 

'F. Tiemann, Ber., 83, 2665. 



DIMETHYJLTRICARBALLYLIC ACID. 51 

Terebic acid, C_H 10 O 4 , 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 chromic 
acid mixture, the following acids l result. 

1. Isoketocamphoric acid, C 10 H 16 O 5 , melts at 128 to 129. It 
is a dibasic ketonic acid, identical with the acid prepared by 
Thiel 2 in the oxidation of a-campholenic acid and described under 
the name of isoxycamphoric acid, C 10 H 16 O 5 . It forms an oxime, 
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 1-pinonic acid with chromic acid. 3 

2. Isocamphoronic acid, 4 C 9 H 14 O 6 , melts at 166 to 167. It 
is a tribasic acid, and has been described by Thiel 2 as an oxida- 
tion product of a-campholenic acid. It is identical with oxy- 
camphoronic acid, obtained, together with other products, by 
Kachler 5 in the oxidation of camphor with nitric acid. Concen- 
trated sulphuric acid converts it into terpenylic acid 6 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 3 may also be obtained from a-dioxydihydrocampho- 
lenic acid or 1-pinonic acid by the more vigorous oxidation with 
chromic acid than is allowed when isoketocamphoric acid is re- 
quired. 

3. Terebic acid, C 7 H 10 O 4 , melts at 174. 

According to Tiemann and Semmler, 1 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. DimethyltricarbaUylic. acid, C 8 H 12 O 6 , 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 

1 Tiemann and Semmler, Ber., 28, 134.4. 

W. Thiel, Ber., 26, 922. 

3 F. Tiemann, Ber., 29, 3006. 

*W. H. Perkin, jun., and Thorpe, Journ. Chem. Soc., 75 (1899), 1897. 

*Kachler, Ann. Chem., 191, 143. 

6 F. Tiemann, Ber., 29, 2612. 



52 THE TERPENES. 

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

2. Oxytrimethylsuccinic acid, C 7 H 12 O 5 , 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 add, C 9 H 12 O g . The latter is a lac- 
tonic acid, and melts at 143.5. 

Oxyisocamphoronic acid, C 9 H ]4 O 7 , 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 1 
from camphor. 

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

By the careful investigation of the above oxidation products 
obtained from pinene, Tiemann and Semmler 2 claim to have 
established the following constitutional formula for this terpene, 




If crude pinene be oxidized with potassium permanganate, the 
keto-lactone, C 1? H 16 O 3 , melting at 63 to 64, is formed from an 
impurity contained in commercial pinene. Tiemann and Semm- 
ler 3 have designated this compound as methyl-S^ethyl-S-hepta- 
non-6-olide-l-3 l . 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 4 came to quite different conclusions regarding the 

Kachler, Ann. Chem., 191, 152. 

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

s Tiemann and Semmler, Ber., 28, 1778. 

A. von Baeyer, Ber., 29, 3, 326, 1907, 1923 and 2776. 



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 10 H 16 O 3 . 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 10 H 16 O 3 
(m. p. 63 to 65). This solid a-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 {3-oxime 
and f-oxime. The ft-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] z> = + 
2 18' (8.2 per cent, solution in ether in a one decimeter tube). 
The f-oxime is less readily soluble than the /5-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 9 H 14 O 4 , and bromoform, while dilute nitric acid oxi- 
dizes it to pinic, oxalic and terebic acids. 

2. Nopic acid, C 10 H 16 O 3 . 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 to 128. It forms crystalline salts with 
the metals. It is an oxy-monobasic acid. 

Bromotetrahydrocumic acid, C ]0 H 15 BrO 2 , 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 10 H 14 O 2 , is formed by the action of hot, 
twenty-five per cent, sulphuric acid or alcoholic potash on the 
preceding compound. It is sparingly soluble in water, crystal- 
lizes from alcohol, melts at 130 to 133, 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 10 H 12 O 2 . 

Nopinone, C 9 H U 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. 1 

According to Wallach, 2 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 10 H 16 O 3 , 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 10 H 16 3 + O = C 9 H M + C0 2 + H,0. 

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

3. Pinoylformic acid, C 10 H 14 O 5 , 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 potassium- 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 10 H ]4 O 5 , is a lactonic acid, which is 
formed by treating pinoylformic acid with hot, dilute sulphuric 

JWallach, Nachr. k. Ges. Wiss., Goettingen, 1899, No. 2. 
'Wallach and Schafer, Ann. Chem., 313, 363. 






PIN AKIN. 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 9 H U O 4 , 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 10 H 16 O 5 , 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. 

a-Ketoisocamphoronic acid ( dimethyltricarballoylformic acid), 
C 9 H 12 O 7 , 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 add; the 
anhydro-add 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 add, C 9 H 12 O 6 , 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 add, C 9 H 14 O 6 . 

The lactone of a-oxydimethyltricarballylic add, C 8 H 10 O 6 , 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 ethyl 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 o-dimethylsuccinic 
acids. 

4. Pinarin, C 10 H U O 3 , 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. Pinic acid, C 9 H 14 O 4 , 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 9 H 13 BrO 4 , 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 9 H 14 O 5 , 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 8 H 12 O 3 , is formed by the oxidation of 
oxypinic acid in a hot, dilute acetic acid solution with lead per- 
oxide. It is an oil, and is soluble in water. Its semicarbazone 
melts at 188 to 189. 

Norpic acid, C 8 H 12 O 4 , 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 8 H 12 O 4 , which Wagner J obtained by the 
action of alkaline hypobromite on pinononic acid, C 9 H 14 O 3 . 

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






/\ ' 
HC<J>CH 



CH Z 
which he calls the " picean-ring" 2 

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 

'G. Wagner and Ertschikowsky, Ber., 29, 881. 
zBaeyer, Ber., 29, 2775. 






CAMPHENE. 57 

oil known from which a solid hydrocarbon, C 10 H ]6 , melting at 
about 30 and boiling at 162, can be separated. This oil is ob- 
tained from JPinus sibirica, and from it Goluboff l isolated a solid 
hydrocarbon, which, according to Bertram and Walbaum, 2 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, 3 camphene occurs in small quantity in oil of spike. Rose- 
mary oil 4 contains inactive camphene. Schimmel & Co. 5 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 Til den 6 ) ; 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 7 ) ; by heating pinene hydriodide with potassium phenolate at 
160 to 170, a very pure camphene is obtained (Wagner 8 ), and 
it may also be made in the same manner from pinene hydrochlo- 
ride (Reychler 9 ). It is also formed from borneol by heating with 
acid potassium sulphate at 200 (Wallach 10 ), 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 n ). 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 

'Goluboff, Cliem. Centr., 1888, 1622. 

2 Bertram and Walbaum, Journ. pr. Chem., N. F., J^9, 15. 

3G. Bouchardat, Compt. rend., Ill, 1094. 

Gildemeister and Stephan, Arch. Pharm., 235 (1897), 582. 

s Semi-annual report of Schimmel & Co., for October, 1897. 

6 Armstrong and Tilden, Ber., 12, 1753. 

'Wallach, Ann. Chem., 239, 6. 

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

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

>Wallach, Ann. Chem., 230, 239. 

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



58 THE TERPENES. 

with a reflux condenser (Bertram and Walbaum 1 ). 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, 3 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 10 H 17 NH 2 = C 10 H 16 + NH 3 . 

In order to prepare camphene, it is most convenient to start 
with borneol, from which bornyl 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 4 ). 

According to Wallach, 5 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 6 ). 

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 

1 Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 8. 
2 Bouchardat and Lafont, Compt. rend., 113, 551. 
'Wallach and Griepenkerl, Ann. Chem., 269, 349. 
*Kachler, Ann. Chem., 197, 96. 
5 Wallach, Ann. Chem., 230, 233; Ber., 25, 916. 
6 Wallach, Ann. Chem., 230, 234. 



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, 1 0.850 at 48. 

According to Bruhl, 8 0.84224 at 54. 

According to Briihl, 2 0.83449 at 63.7. 

The coefficients of refraction are : 

n c = 1.4555 at 48 (Wallach and Pulfrich 1 ). 
n Na = 1.4514 at 54 (Bruhl 2 ). 
n Na = 1.45085 at 63.7 (Briihl 2 ). 

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 3 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, [aj^ = 80 37' (Bouchardat and Lafont 4 ). 

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, 5 while 
in contrast to pinene, dilute sulphuric acid acts slowly upon it. 6 

According to Marsh and Gardner, 7 phosphorus pentachloride 
converts camphene into a reaction-product, which, when treated 
with water, is resolved into two crystalline acids, a-camphene- 
phosphorous acid, (C )0 H I5 PO 3 H 2 ) 2 -|-H 2 O, and /9-camphene-phos- 
phorous acid, C 10 H,.PO 3 H 2 ; the salts of the latter decompose 
readily on heating into meta-phosphoric acid and camphene. 

i Wallach, Ann. Chem., 245, 210; 252, 136. 

zBriihl, Ber., 25, 160. 

"Compare Bruhl, Ber., 25, 170. 

4 Bouchardat and Lafont, Coinpt. rend., 104, 693. 

sWallach, Ann. Chem., 230, 234. 

sWallach, Ann. Chem., 239, 9. 

7 Marsh 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 1 ). 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 2 converts the 
latter into an ester of isoborueol, which, on saponification, yields 
isoborneol. 

A compound of camphene with nitrosyl chloride has not been 
obtained. 3 

The action of nitrous acid on camphene has been investigated 
by Jagelki ; 4 he obtained the following compounds. * 

1. Camphene nitronitrosite, C 10 H 16 -N 3 O 5 . 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 10 H 16 N 2 O 3 . 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 potassium 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 10 H 15 NO 2 . 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 ligroiue. 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 10 H 16 O, by the reduction with tin and hydro- 
chloric acid or with zinc dust and acetic acid ; this aldehyde is 

'Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 1. 
2 A. Reychler, Ber., 29, 695. 
"Wallach, Ann. Chem., 245, 255. 
*W. Jagelki, Ber., 82, 1498. 



CAMPHENE HYDRIODIDE. 61 

also obtained by Bredt and Jagelki l in the oxidation of camphene 
with chromyl chloride. Oxidation with potassium permanganate 
or treatment with alcoholic potash converts camphenilic nitrite 
into camphenilone 2 (camphenylone), C 9 H 14 O. 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 10 H 16 -HC1. According to Reychler, 3 
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 4 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 bornyl chloride. 

According to Jiinger and Klages, 5 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. 6 

Camphene hydrobromide, 6 C 10 H 16 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, 7 C 10 H 16 -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 (?). 

By the action of phosphorus trichloride and bromine on cam- 
phor, Marsh and Gardner 8 obtained a- and ft-tribromocamphene 

iBredt and Jagelki, Ann. Chem., S10, 112. 

zBalaise and Blanc, Compt. rend., 129 (1899), 886. 

3 A. Reychler, Ber., 29, 697. 

*A. Reychler, Bull. Soc. Chim., 1896 (III.), 15, 366. 

5 Jiinger and Klages, Ber., 29, 544. 

eSemmler, Ber., 33, 3420. 

7 Kondakoff and Lutschinin, Chem. Zeit., 25, 131. 

8 Marsh and Gardner, Journ. Chem. Soc., 71, 285. 



62 THE TERPENES. 

hydrobrmnide, C 10 H 14 Br 4 , melting at 168, and 143 to 144, re- 
spectively ; both compounds yield tribromocamphene, C 10 H 13 Br 3 , 
melting at 75 to 76, when treated with sodium methylate. The 
action of phosphorus pentachloride on camphor yields a-chloro- 
camph&ne hydrochloride, C 10 H 16 C1 2 , melting at 165, and the latter 
is converted into a-cMorocamphene, C 10 H 15 C1, by the action of zinc 
dust and glacial acetic acid. By the action of sulphuric acid con- 
taining five per cent, of water, a-chlorocamphene is converted into 
a compound, C 10 H 16 O, which was at first called " oxycamphene " 
or " camphenol " l ; this oxygen-containing compound was sub- 
sequently investigated by Marsh and Hartridge, who changed its 
name to carvenol, C 10 H 16 O ; it is quite probable that this com- 
pound is identical with the ketone, C 10 H, 6 O, previously described 
by Wallach 2 under the name of carvenone. 

a-Dichlorocamphene, C ]0 H 14 C1 2 , is a derivative of camphor, which 
was prepared by Lap worth and Kipping 3 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. 

Monobromocam.pb.ene, C 10 H 15 Br. According to Wallach, 4 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. 5 

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 6 as an 
oil, boiling at 226 to 227 j it has the specific gravity 1.265 at 
15, the index of refraction, n^ = 1.52605 at 15, and the 
molecular refraction, M = 52.36. 

Camphene dibromide, C 10 H 16 Br 2 . According to Reychler, 7 when 
camphene is brominated according to Wallach's method and the 
monobromocamphene, C 10 H 15 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, 

i Marsh and Hartridge, Journ. Chem. Soc., 73, 852. 
z Wallach, Ann. Chem., 277, 122. 

"Lapworth and Kipping, Journ. Chem. Soc., 69, 1559; see also, 69, 1546; 
63, 548. 

*Wallach, Ann. Chem., 230, 235. 
6 Semmler, Ber., S3, 3420. 
6 Jiinger and Klages, Ber., 29, 544. 
7 A. Reychler, Ber., 29, 900. 



ANHYDROCAMPHOIC ACID. 63 

melts at 90, and has the composition, C 10 H 16 Br 2 . It is likewise 
formed by slowly adding bromine to a solution of camphene in 
light petroleum, cooled to 10. 

According to Semmler, 1 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 
alcohol to a dihydrocamphene identical with that from pinene 
hydrochloride. 

Oxidation of Camphene. 

A chromic acid mixture converts camphene into camphor, oxy- 
camphor, C 10 H 16 O 2 , carbonic acid, acetic acid and camphoric acid 
(Kachler and Spitzer 2 ). (According to more recent investigations 
by Semmler, 1 it is stated that camphene is never oxidized to cam- 
phoric acid.) 

According to Wagner, 3 the oxidation of camphene with a dilute 
solution of potassium permanganate in the cold yields camphene 
glycol, C 10 H 16 (OH) 2 , melting at 192, and camphenilie acid, 
C 10 H 16 O 3 , melting at 170 to 172. 

By the oxidation of camphene with dilute nitric acid, Marsh 
and Gardner 4 obtained the following acids. 

1. Camphoic acid (camphoylic or carboxyl-apocamphoric acid), 
C 10 H 14 O 6 . This tribasic 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- 
phoric acid, C 10 H 14 C1-PO 3 H 2 (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 9 H 12 O 3 , and isocamphopyric acid, C 9 H 14 O 4 (in. p. 209). 

Anhydrocamphoic acid, C 10 H ]2 O 5 , is formed by the action of 
acetyl chloride on camphoic acid ; it crystallizes from ether in 
large, transparent plates, melting at 205. 

i Semmler, Ber., S3, 3420. 

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

G. Wagner, Ber., 23, 2311. 

'Marsh 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, 1 C 9 H U O 4 , melting at 203 to 204, 160 to 
170, and 190 to 191, respectively; and cis-camphopyrie anhy- 
dride, C 9 H 12 O 3 , melting at 178. 

2. Terephthalic acid, camphoric acid, C IO H 16 O 4 , and succinic acid. 

In addition to camphoic acid, Jagelki 2 obtained the following 
compounds by the oxidation of camphene with dilute nitric acid. 

1. Anhydrocamphenilic acid, C 10 H U O 2 , crystallizes in plates and 
melts at 147.5 to 148. Since it is indifferent towards potas- 
sium permanganate, Wagner 3 regards it as a derivative of a class 
of compounds which he terms tricyclenes. 

2. Camphenilone, C 9 H U O, is a ketone, melting at 36 to 38 and 
boiling at 195 under 738 mm. pressure. 4 It is also formed by 
the oxidation of camphenilic acid, C 10 H 16 O 3 , 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 9 H 15 OH, which, in turn, may be converted into a 
chloride, C 9 H 15 C1 ; when the latter is heated with aniline, it yields 
an unsaturated hydrocarbon, camphenilene, C 9 H 14 , 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 9 H 13 N ; by hydrolysis, this yields the unsaturated campho- 
ceenic add,, C 9 H 14 O 2 , melting at 54. If this acid be oxidized 
with a cold, dilute solution of potassium permanganate, it gives 
rise to dioxycamphoceanic acid, C 9 H 16 O 4 , melting at 163 ; on dis- 
tillation in vacuum this dioxy-acid is converted into a mixture of 
a ketonic acid, camphoceonic add, C 9 H 14 O S , melting at 173, and 
the lactone of oxy camphoceonic add, C 9 H 14 O 3 , melting at 58. 
When dioxycamphoceanic acid is oxidized with dilute nitric 
acid, it yields dimethyltricarbattylic add, C 8 H 12 O 6 , melting at 157 
to 158, which, on fusion with potash, gives rise to oxalic acid 
and as-dimethylsuccinic acid, C 6 H 1U O 4 . 

3. Camphenilic nitrite, C 10 H 15 NO 2 (see above). 

By the action of nitric anhydride on a solution of camphene in 
chloroform, an add, 6 C 10 H 15 O 5 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 camphopyric (apocamphoric) acid, compare 
Komppa, Ber., 84, 2472. 

*W. Jagelki, Ber., 82, 1498 ; compare Bredt and Jagelki, Chem. Zeit., SO 
(1896), 842. 

3 Majewski and G. Wagner, Journ. Russ. Chem. Soc., 29 (1896), 124; 
Chem. Centr., 1897 (I.), 1056. 

*Blaise and Blanc, Compt. rend., 129 (1899), 886. 

5 Demjanoff, Journ. Russ. Phys. Chem. Soc., 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 intoanhydrocamphenilic acid, C 10 H I4 O 2 (m. p. 148). 

The compound, 1 C 10 H 16 -2OO 2 C1 2 , is formed when a solution of 
camphene in carbon bisulphide is treated with chromyl dichloride. 
It is a pale brown powder, very hygroscopic, and is somewhat 
soluble in ether. 

Camphenilan aldehyde, C 10 H 16 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 ]0 H 14 O, previously prepared by fitard, 
and also by Wagner from camphene glycol and hydrochloric acid. 
* Camphenilanic acid, C 10 H 16 O 2 , results by the oxidation of carn- 
phenilan aldehyde with a current of air; it melts at 65. When 
the aldehyde is oxidized by the usual oxidizing agents it yields 
isocamphenilanic acid, C 10 H 16 O 2 , 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 oxy camphenilanic acid, C 10 H )6 O 3 ; this acid melts at 
170 to 172, and is identical with camphenilic acid, C ]0 H, 6 O 3 , 
which Wagner obtained in the oxidation of camphene with potas- 
sium permanganate. 

Two isomeric nitrates, C 10 H 16 -HNO 3 , have been obtained by 
Bouveault 2 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. 

Ethylcamphene, C 10 H 15 C 2 H 5 , and isobutylcamphene, C 10 H 1;( C 4 - 
H 9 , were prepared by Spitzer,^ and hydrazocamphene, C 10 H 17 NO 2 , 
was obtained by Tan ret. 4 

Camphene alcoholate, 5 C, H 17 OC 2 H 5 , 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, 
n^ = 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- 

JBredt and Jagelki, Ann. Chem., 310, 112. 
*L. Bouveault, Bull. Soc. Chim., 23 (1900, III.), 535. 
aSpitzer, Ann. Chem., 197, 133. 

'Tanret, Compt. rend., 102, 791; 104, 917; 106, 660 and 749; Ber., 20, 
253 and 285, Ref. ; 21, 237 and 352, Ref. 
sSemmler, Ber., S3, 3420. 

5 



66 THE TERPENES. 

tained by Forster ; for a description of the method of prepara- 
tion, properties, etc., of these substances (bromonitrocamphane, 
C 10 H 16 BrNO 2 , nitrocamphene, C 10 H 15 NO 2 , amidocamphene, C 10 - 
H 15 NH 2 , hydroxycamphene, C 10 H 15 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 fenchyl alcohol). 

The methods for the artificial preparation of this terpene are 
limited to the reduction of fenchone, C 10 H 16 O, and elimination of 
the elements of water from the resulting fenchyl alcohol, C 10 H 17 OH. 
Fenchene is formed when fenchyl alcohol is heated with acid 
potassium sulphate. 

In order to prepare fenchene, it is most convenient to convert 
fenchyl 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 2 ). 

PROPERTIES. According to Wallach, 2 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, 3 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 4 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 ; 

>M. O. Forster, Journ. Chem. Soc., 77, 261 ; 79, 644, 653, 987 and 1003. 
* Wallach, Ann. Chem., 26S, 149; 302, 376. 

'Gardner and Cockburn, Journ. Chem. Soc., 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-feuchone, Wallach 
designates them as D-d-fenchene and D-f-fenchene, respectively. 1 
The optical rotation of fenchyl chloride, obtained from D-1-fenchyl 
alcohol, varies between the limits, []= 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, fenchyl 
chloride yields a mixture of 1- and d-fenchene, which is optically 
inactive or dextrorotatory. The limits of rotation for 1- and 
d-fenchene are, [] B = 21, in a one decimeter tube. Dextro- 
fenchene is best prepared from fenchyl 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-fencheue is oxidized in a few minutes, 
while D-1-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 2 in 
his first investigation of fenchene. 

Levo-fenchyl chloride 3 is formed by saturating a solution of 
either d- or 1-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, 
1-fenchene is obtained ; by this method, therefore, d-fenchene may 
be converted into 1-feuchene. 

L-d-Fenchyl alcohol, obtained from 1-fenchone, acts in a similar 
manner to D-1-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). 

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

Wallach, Ann. Chem., 263, 150. 

"Wallach, Ann. Chem., 802, 382. 



68 THE TERPENES. 

According to Kondakoff, 1 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 []/> = 55 ; it 
shows the properties of a reduced aromatic compound with a 
double linking in the ring. 

Fenchene hydrochloride, 2 C 10 H 16 .HC1, closely resembles fenchyl 
chloride, C 10 H 17 C1, and is probably almost all tertiary ; moist 
silver oxide converts it into isofenchyl alcohol. 

Fenchene hydrobromide, 2 C 10 H 16 HBr, resembles fenchyl bro- 
mide; [] 1) =-27 16 / . 

Fenchene hydriodide, 3 C 10 H 16 .HI, boils at 120 to 120.5 
(23 mm.), has asp. gr. 1.427 at 21/4 and [d] D = + 4257' 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 fenchyl 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, 4 C 10 H 17 OH, 
melting at 61.5 to 62. This transformation is similar to that 
of camphene into isoborneol. 

Fenchene alcoholate, 5 C 10 H 17 OC 2 H 5 , 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 deriv- 
ative of the alcohol, C 10 H 17 OH. This alcohol melts at 61, and 
is identical with isofenchyl alcohol. 

Oxidation Products of Fenchene. 

As is mentioned above, D-d- and D-1-fenchene react quite dif- 
ferently toward potassium permanganate. Twenty grams of D-l- 
fenchene require about twelve hours to be oxidized in the cold with 
a three per cent, solution of permanganate, while under the same 

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

*Kondakoff, Journ. pr. Chem., 1900 (II.), 62, I. 
Kondakoff, Chem. Zeit., 25, 131. 

'Bertram and Helle, Journ. pr. Chem., 61, 1900 (II.), 293. 
6 Wallach, Ann. Chem., 315, 273. 



FENCHOCAMPHOKONE. 69 

conditions D-d-fenchene is completely oxidized in a few minutes. 
The product is in each case an oxyfenchenic acid, 1 Ci H 16 O 3 . 

1. D-1-Oxyfenchenic acid, 2 C 10 H 16 O 3 , is the oxidation product of 
pure D-1-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, [0^]^= 56.8. The same acid 
may also be obtained by the oxidation of D-1-fenchyl chloride 
with permanganate. Its acetyl derivative melts at 109 to 
110. 

D-d-Fenchocamphorone, 3 C 9 H 14 O, is formed by the oxidation of 
D-1-oxyfenchenic acid in an acid solution. It melts at 109 to 
110, boils at 202, and is dextrorotatory, [a\ D = + 14.64. It 
is a ketone isomeric with phorone, has the odor of camphor, and 
is very similar to it. Its oxime, C 9 H 14 NOH, melts at 69 to 71, 
is levorotatory, [a] D = 50.30, and yields fenchocamphoni- 
trile, 3 C 9 H 13 N, on treating with dilute sulphuric acid. On re- 
ducing this nitrile with alcohol and sodium, a base, C 9 H 1S NH 2 , is 
obtained, and is identified by means of its platinochloride and 
carbamide. An isomeric fenchocamphylamine, C 9 H ]5 -NH 2 , 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 9 H 15 -NH 2 -HC1, is very stable, 
and crystallizes from a mixture of ether and alcohol. 

Fenchocamphorone semicarbazone melts at 210 to 212, and is 
levorotatory, [] z ,= 131.3. 

Fenchocamphorone 4 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 9 H 14 O 4 , and yields 
the anhydride, C 9 H 12 O 3 (m. p. 176 to 177), and a monanilide 
(m. p. 211). These compounds agree in their properties with 
the corresponding derivatives of cis-camphopyric acid, 5 and hence 
the two acids are identical (see page 64). 

When fenchocamphorone is reduced by sodium and aqueous 
ether, fenchocamphorol, 6 C 9 H 15 OH, is obtained ; it crystallizes from 
dilute methyl alcohol in needles, melting at 128 to 130. A 
pinacone, C 18 H 30 O 2 , melting at 192 to 193, is also formed dur- 
ing the reduction. 

'Wallach, Ann. Chem., 284, 333; 309, 313; 815, 273. 
*Wallach, Ann. Chem., 802, 377. 

"Wallach, Ann. Chem. 800, 313; 302, 383; 315, 273; Chem. Centr., 1899 
(II.), 1052. 

'Wallach, Ann. Chem., 300, 313; 315, 273. 
'Marsh and Gardner, Journ. Chem. Soc., 69, 77. 
Wallach, Ann. Chem., 300, 313. 



70 THE TERPENES. 

2. D-d-Oxyfenchenic acid, 1 C 10 H 16 O 3 , 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, [].p= +7.696. Other acids are simultaneously 
formed with this compound, but they have not yet been obtained 
pure. Its acdyl derivative crystallizes in prisms, and melts at 
122 to 124. 

D-l-Fenchocamphorone, 1 C 9 H 14 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] i) = 16.69. Its oxime is very soluble 
in all solvents, melts at 54 to 56, and is dextrorotatory, 
[aj^rs + 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, [] = + 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-1-fenchocamphorone melts at 
125 to 130, whilst os-dimethylsuccinic anhydride melts at 29 
(Wallach 2 ). 

3. L-d-Oxyfenchenic acid, 3 C 10 H 16 O 3 . This compound is pre- 
pared as follows. 1-Fenchone is reduced to L-d-fenchyl alcohol 
([a] B = + 10.36), and the latter is converted into fenchyl 
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, [] = + 57.29. 

The racemic oxyfenchenic acid, 3 C 10 H 16 O 3 , is prepared by crystal- 
lizing from ether a mixture of equal quantities of D-1-oxyfenchenic 
acid and L-d-oxyfenchenic acid ; it melts at 142 to 143, lower 
than either of its components. 

The L-1-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-l- and D-d-oxyfenchenic acids, 

JWallach, Ann. Chem., 302, 378 and 384. 
"Wallach, Ann. Chem., 315, 273. 
Wallach, Ann. Chem., 302, 378 and 379. 



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 add, 1 C 8 H 12 O 3 ; the latter gives a semicarbazone, melting 
at 210, and a silver salt. This ketonic acid may possibly be 
formed from a third isomeric fencheue, which is contained in 
crude fenchene. 

Fenchene diifers 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, 2 
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 9 H 14 O 4 , is obtained from the non- 
volatile oil remaining in the distilling flask ; it melts at 207. 

3. Cis-camphopyric anhydride, C 9 H 12 O 3 , melts at 178. 

4. An add 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 3 is 
found in the following ethereal oils : oil of orange 4 and orange 
peel, 4 lemon, 4 bergamot, 4 caraway, 4 dill, 4 erigeron, 5 kuromoji, 6 
massoy bark, 7 and celery. Levo-limonene occurs in the oil from 

iWallach, Ann. Chem., 315, 273. 
2 Gardner and Cockburn, Journ. Chem. Soc., 73, 277. 

Gildemeister and Stephan, Arch. Pharm., 235 (1897), 582; see also J. 
Flatan and Labb<, Bull. Soc. Chim., 19, 1898 (III.), 361 and 364. 
*Wallach, Ann. Chem., 227, 287. 
sBeilstein and Wiegand, Ber., 15, 2854. 
eKwasnick, Ber., 24, 81. 
'Wallach, Ann. Chem., 258, 340. 



72 THE TERPENES. 

cones 1 and needles 2 of Abies alba, Russian peppermint oil, 3 and 
Russian and American spearmint oil. 

PREPARATION. The most convenient source of this terpene is 
oil 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- 
rad y, 4 as follows : 

Levo-limonene, [J. = 105.0. 

Dextro-limonene, [a\ D = + 106.8. 

Kremers 5 found the specific rotatory power of freshly distilled 
limonene to be higher, viz. : 

[]= 121.3. 

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

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

According to Godlewsky, 6 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, and a specific rotatory power, \_a\ D = + 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- 

1 Wallach, Ann. Chem., 246, 221. 
"Bertram and Walbaum, Arch. Pharm., 231, 290. 
3 Andres and Andrejew, Ber., 1892, 609. 
*Wallach and Conrady, Ann. Chem., 252, 144. 
6 Kremers, Amer. Chem. Journ., 17, 692. 

6 J. Godlewsky and Roshanowitsch, Chem. Centr., 1899, I., 1241 ; J. Russ. 
Chem. Soc., 81, 209. 






LIMONENE TETRABROMIDE. 73 

ner. Limonene is also rendered inactive by heating to high tem- 
peratures (Wallach 1 ). 

Limonene tetrabromide, 2 C 10 H 16 -Br 4 , 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, 3 and Power and Kleber. 4 

Limonene tetrabromide is optically active, and separates in 
hemihedral rhombic crystals, 5 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. 6 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^HigB^ 2HBr=C 10 H 14 Br 2 , 
II. C 10 H u Br 8 +KOCH 3 =C 10 H u BrOCH 3 +KBr. 

The resulting compound, C 10 H 14 BrOCH 3 , 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, n^ = 1.51963, 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 10 H 14 BrOCH 3 , is re- 
placed by hydrogen, and carveol methyl ether, C 10 H ]5 OCH 3 , 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, n^, = 1.47586, at 18. This carveol methyl 

i Wallach, Ann. Chem., 227, 301. 

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

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

'Power and Kleber, Arch. Pharrn., 232, 646. 

s Hintze, Zeitschrift fur Krystallographie, 10 [2]. 

sWallach, 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. 1 Dextro-car- 
vone is reduced to dihydrocarveol, which is readily converted into 
methyl dihydrocarvyl xanthate, C 10 H 17 O CS 2 . CH 3 ; 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 limouene 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. 2 

Limonene nitrosochlorides, C 10 H ]6 -NOC1, 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 /3-limonene nitrosochlorides. There are, there- 
fore, four isomeric, optically active limonene nitrosochlorides, and 
corresponding to them, are two inactive modifications, the a- and 
/?-dipentene nitrosochlorides. 

PREPARATION OF THE NITROSOCHLORIDES FROM 
DEXTRO- AND LEVO-LIMONENE. 3 

To a mixture of five cc. of limonene, seven cc. of amyl 
nitrite (or eleven cc. 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 cc. 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 /9-LIMONENE NITROSOCHLOR- 
IDES. 

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

>L. Tschugaeff, Ber., 33, 735. 
s Wallach, Ann. Chem., 281, 137. 
'Wallach, Ann. Chem., 252, 106; 270, 174. 



LJMONENE NITEOSOCHLOEIDES. 75 

moments in the cold. It is then filtered, and the crude /9-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-com pound 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 /9-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 /9-limonene 
nitrosochloride is obtained ; after drying, this compound forms 
soft needles, which melt at about 100. The /9-nitrosochlorides 
may be kept for a long time without decomposing. The crude 
limonene nitrosochlorides contain only about twenty per cent, of 
the /9-nitrosochlorides. 

(For the influence of the concentration of the hydrochloric acid on 
the yield of /9-nitrosochlorides, compare experiments of Wallach. 1 ) 

According to Wallach, 2 the a- and /9-nitrosochlorides are phys- 
ical, and not chemical isomerides. While Wallach gives them the 
formula, 

/ C1 

^10^15^ 

\NOH 

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



76 THE TEKPENES. 

Baeyer 1 is inclined to consider these compounds as possessing 
double that molecular weight, and to regard them as bisnitrosyl- 
derivatives. Wallach 2 has, however, published the results of ex- 
periments, which indicate that the a- and ^-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 /9-limonene nitroso- 
chlorides form the same carvoxime, melting at 72. 

Benzoyl limonene nitrosochloride, 3 



CKA 



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 /9-limonene nitroso- 
chloride with one molecule of benzoyl chloride and eighty times its 
weight of dry ether for several days on a 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 4 by boiling with sodium alcoholate. 

Limonene nitrosobromide, 5 C 10 H 16 . NOBr, is obtained by a method 
analogous to that used in the preparation of the nitrosochloride. 
It melts at 90.5. 

Limonene nitrosate/' 

/ONO, 



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

LIMONENE NITROL AMINES. 6 

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

Baeyer, Ber., 28, 648. 

2 Wallach, Ber., 28, 1308 and 1474. 

nVallach, Ann. Chem., 270, 175. 

'Wallach, Ber., 28, 1311. 

5 Wallach, Ann. Chem., 245, 258. 

Wallach, Ann. Chem., 252, 113; 270, 180. 



LIMONENE NITROLANILIDES. 77 

optically dextrorotatory and is called a-nitrolamine, the other is 
levorotatory, and termed /9-nitrolamine. If dextro-/3-limonene 
nitrosochloride be treated with the same base, exactly the same 
reaction-products are obtained, namely, a dextrorotatory a-limo- 
nene nitrolamine, together with a levorotatory /9-limonene nitro- 
lam ine. If, on the other hand, levo-a- or levo-/3-limonene 
nitrosochloride be treated with an amine, a mixture of a levo- 
rotatory a- and a dextrorotatory /?-limonene nitrolamine is formed. 
These a- and /9-nitrolamines have simple molecules (Wallach 1 ). 

If equal proportions of the two oppositely active a-, or /?-limo- 
neue nitrolamines are recry stall ized together, the corresponding 
a- or /9-dipentene nitrolamine is obtained. These may also be 
prepared together by a precisely analogous method from the a-, as 
well as from the /?-, dipentene nitrosochloride. The following 
table may serve to explain these transformations (page 78). 

1. Limonene nitrolanilides, 



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 ,3-anilide, the alcholic-acid filtrate from 
the hydrochloride of the a-base is poured into a large excess of 
ammonium hydroxide. The /?-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 /9-anilide sepa- 
rates from this solution on cooling, while the remainder may be 
precipitated by the addition of petroleum ether. /9-Limonene 
nitrolanilide crystallizes from alcohol in moss-like needles, which 
melt at 153. It is difficultly soluble in ether, readily soluble in 
chloroform. 

'Wallach, Ber., 28, 1311. 



78 



THE TERPENES. 




3 a 



LJMONENE NITROLBENZYLA MINES. 79 

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

xNOH 

^lO^isV 

\N(NO)C 6 H 6 

are formed. The a-nitroso-compound melts at 142, while the 
/9-derivative, characterized by its great power of crystallization, 
melts at 136. 

2. Limonene nitrolpiperidides, 



^Iflf-lSv 

\NC 5 H 10 

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 fi-ba.se 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 /9-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 /9-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 /?-base is dried, digested with cold petroleum ether, 
and the undissolved portion recrystallized from warm petroleum 
ether with the addition of some methyl alcohol. /9-Limonene 
nitrolpiperidide melts at 110 to 111. 

3. Limonene nitrolbenzylamines, 



x 
C,oH,,f 

\NHCH 2 C,H 6 

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 TERPENE8. 

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

Emil Fischer 1 and other investigators have suggested that the 
isomerism of the a- and /9-limonene nitrolamines is to be explained 
as stereo-chemical isomerism. According to Wallach, 2 however, 
the known facts do not determine whether the a- and /9-15monene 
nitrolamines, in contrast to the nitrosochlorides, have the same or 
different chemical structure. The following observations argue 
against the stereo-chemical theory. 2 

1. No transformations of the a- into the /9-limonene nitro- 
lamines, or the ft- into the a-derivatives, have yet succeeded. 

2. a-Limonene nitrolanilide is a weaker base than ^-limonene 
nitrolanilide. 

3. On heating, the a-anilide yields aniline and a product con- 
taining carvoxime ; the /?-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, 



x 

l/ 
X 



NH.C 6 H S 

obtained from hydrochlorolimonene nitrosochloride. Under the 
same conditions, /9-limoneue nitrolanilide forms a compound, 
C 16 H 23 C1N 2 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 /?-limonene nitrolanilides possess 
the same molecular weight (determined by the boiling point 
method, dry ether being the solvent). 

Limonene hydrochloride, C 10 H 16 HC1. 

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 

!Emil Fischer, Ber., 23, 3687 ; 2J h 2G86. 
'Wallach, Ann. Chem., 210, 180. 



HYDROCHLOROLIMONENE NITROSATE. 81 

by distillation under diminished pressure, and the resulting limo- 
nene nionohydrochloride rectified in vacuum (Wallach, Kremers 1 ). 

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. 1 

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 di hydrochloride, while under the same conditions, 
hydrogen bromide converts it into a compound melting at 47 
to 48. 

According to a preliminary notice by Semmler, 2 the chlorine 
atom in limonene hydrochloride can be replaced by a hydroxyl- 
group, thus forming an optically active terpineol. 

Hydrochlorolimonene nitrosochloride, C 10 H 17 C1 NOC1, 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 8 ). 

Hydrocblorolimonene nitrosate, 3 C 10 H 17 C1 NO(ONO 2 ), 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 

1 Wallach and Kremers, Ann. Chem., 270, 188. 
'Semmler, Ber., 28, 2189.- 
Wallach, Ann. Chem., 245, 260. 
6 



82 THE TERPENES. 

nitrosate was first obtained by Maissen 1 ; its constitution was ex- 
plained by Wallach's investigation. It melts at 108 to 109. 
Hydrochlorolimonene nitrolamines, 

NO 

NHK 

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 2 ). 

Hydrochlorolimonene nitrolbenzylamine, 2 

NO 
NHCH 2 C 6 H 5 

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, 2 

, / NO 
\NHC 6 H 5 

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

'Maissen, Gazz. Chim., 18, 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, NO 

Cl ' Hl ' C < NH C 6 H 5 

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. 1 

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 10 H 18 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 aoetyl 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, 3 C 10 H 15 OH. 

OXIDATION PRODUCTS OF LIMONENE. 

The earlier publications 4 regarding the oxidation of limonene 
state that a chromic acid mixture converts limonene into carbonic 
anhydride, acetic acid, and a liquid camphor, C ]0 H ]fi O, but 
that nitric acid oxidizes it to oxalic acid and hesperic acid, 
C 20 H 26 O 17 + 2H 2 O. Tilden and Williamson 5 showed that when 

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

20. Kriewitz, Ber., 32, 57. 

3P. Genvresse, Compt. rend., 182, 414. 

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

sTilden and Williamson, Journ. Chem. Soc., 63 (1893), 298; 53 (1888), 
880. 



84 



THE TERPENES. 



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

G. Wagner l obtained a tetrahydric alcohol, limonetrol, C 10 H 16 - 
(OH) 4 , by the oxidation of liraonene with potassium perman- 
ganate. 

According to Godlewski, 2 oxyterpenylic deid, C g H 12 O 5 , 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 3 in the oxidation of carvone with perman- 
ganate. The dilaetone of the acid, C 8 H 10 O 4 , melts at 129 to 
130, and is reconverted into oxyterpenylic acid by the action of 
potassium hydroxide. 

Semmler 4 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, or^o-derivatives. In 
accordance with this suggestion, limonene, which is regarded as 
having the formula, 




H : 



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




iG. Wagner, Ber., 1S90, 2315. 

"J. Godlewsky, Chem. Centr., 1899 (L), 1241; Journ. Rusa. Chem. Soc., 
SI (1899), 211. 

3 0. 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 1 concludes that 
terpinene is to be regarded as pseudo-limonene.) 

It should also be mentioned that Baeyer 2 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 zinc dust, and then with sodium and alcohol, para-cymene is 
obtained. 

The values for the rotatory powers of the limoneue 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 /?-nitrolamines 
are formed from the nitrosochlorides ; the a-nitrolamines, which 
are formed together with the /?-nitrolamines, rotate" the plane of 
polarized light in the same direction as the original nitrosochlo- 
rides. 

4b. DIPENTENE. 

Dipentene is the optically inactive 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 3 showed, how- 
ever, that all these substances contain dipentene as their principal 
constituent, and are, therefore, to be regarded as identical. 

Semmler, Ber., S4, 708. 
*Baeyer and Villiger, Ber., 31, 1401. 

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



86 



THE TERPENES. 



O 

a" 
c 
<J 

es 



ooooo ooooooooooooo 



I od o r-~ o co ci I-H ess o oi o oi 



i-i ec <r) .-H r-i 



I 1 + 



oooo ooooooooooooo 

*f OO (M < 



00 CO i-l OO 



. t- b- o co co 



+ 11 + 










lilll 



= = 



. 






1 11 

" 



DIPENTENE. 87 

Dipentene is contained in camphor oil, 1 Russian 3 and Swedish 
turpentine oil, 2 oil of pine needle from Picea excelsa, 3 oil of 
cubebs, oil of limetta leaf, oil of kesso-root, oil of olibanum, 4 oil 
of mace, 4 oil of wormwood, 1 oil of bergamot, oil of fennel, oil of 
kuromoji, 5 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, 2 
as well as in the products of the distillation of pine roots and fir- 
wood. 6 Dipentene is also obtained from the distillation products 
of vegetable resins, as copal resin, soft Elemi resin and colo- 
phonium. 7 Essence of resin also contains dipentene as shown by 
Renard's 8 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, 9 C 5 H g , at 250 
to 270 ; it is also found with isoprene in the products of the dry 
distillation of caoutchouc. 10 Pinene is converted into dipentene 
by heating to 250 to 270 . 12 Dipentene is obtained by mixing 
equal quantities of dextro- and levo-limonene ; ll 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, 13 cineole, C 10 H 18 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 

iWallach, Ann. Chem., 227, 296. 
2 Wallach, Ann. Chem., 230, 244 and 246. 
3 Bertram and Walbaum, Arch. Pharm., 231, 290. 
'Wallach, Ann. Chem., 252, 100. 
5 Kwasnick, Ber., 24, 81. 
"Aschan and Hjelt, Chem. Ztg., 18, 1566. 
'Wallach and Rheindorf, Ann. Chem., 271, 310. 
sRenard, Ann. Chim. Phys. (6), 1, 223. 

9 Wallach, Ann. Chem., 227, 295; Bouchardat, Compt. rend., 89, 1217. 
10 Wallach, 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., 2^6, 225. 
"Wallach, Ann. Chem., 227, 289. 
-3Wallach, Ann. Chem., 230, 255. 



88 THE TERPENES. 

acid potassium sulphate, 1 or by boiling with a twenty per cent, 
phosphoric acid solution. Terpineol, C 10 H 17 OH, yields dipentene 
when heated with acid potassium sulphate. 2 

Of especial interest is the formation of dipentene from linalool ; 
according to Bertram and Walbaum, 3 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, 4 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 c = 1.47308. 6 

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

According to Tilden and Williamson, 7 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. 

iWallach, Ann. Chem., 230, 255. 

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

3 Bertram and Walbaum, Journ. pr. Chem., N. F., 45, 601. 

Wallach, Ann. Chem., 227, 286; 245, 196. 

5 Wallach, Ann. Chem., 289, 3. 

eWallach, Ann. Chem., 245, 197. 

'Tilden and Williamson, Journ. Chem. Soc., 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. 1 

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, 2 C 10 H 16 . HC1, 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 3 ). 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 10 H 16 . 2HC1, 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. 
K 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 

1 Wallach, Ann. Chem., 239, 15. 
2Wallach, Ann. Chem., 245, 247; 270, 188. 

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



90 THE TERPENE8. 

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 1 ). 

Dipentene dihydrochloride melts at 50, and boils at 118 to 
120 under a pressure of 10 mm. 2 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, 3 and Tilden. 4 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, 5 a cw-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, 6 C 10 H 17 C1 3 , 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. 
"Montgolfier, Ann. Chim. Phya. (5), 19, 155. 
'Tilden, Jahresb. Chem., .7878, 639. 
"Baeyer, Ber., 26, 2863. 
6 Wallach and Hesse, Ann. Chem., 270, 196. 



DIPENTENE DIHYDROBROMIDE. 91 

dihydrobromide, which melts at 110 and is prepared from dipen- 
tene dihydrobromide, is treated with alcoholic potash, a hydro- 
carbon, C 10 H 14 , is obtained; the trichloride, however, yields a 
product consisting principally of an unsaturated, liquid dipentene 
dichloride when it is submitted to the action of sodium alcoholate 
or sodium acetate (Wallach and Hesse 1 ). 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 10 H 16 Cl 2 Br 2 , melting at 98. It 
formed a nitrosochloride, melting at 111, which was converted 
into a nitrolanilide, 

xNO 
Ci H 16 Cl 2 ^ 

\NHC 6 H 5 

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

Dichlorodipentene dihydrochloride, C 10 H 16 C1 4 , is prepared when 
dipeutene 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 10 H 16 -2HBr, was first obtained by 
Oppenheim 2 by treating terpine with phosphorus tribromide. 
Hell and Hitter 3 prepared the same compound by the action of 
hydrobromic acid on wormseed oil. According to Wallach, 4 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 8 ). 

iWallach and Hesse, Ann. Chem., 270, 196. 
'Oppenheim, Jahresb. Chem., 1862, 459. 
"Hell and Hitter, Ber., 17, 2610. 
Wallach, Ann. Chem., 239, 12. 
sBaeyer, 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 dihydrobromide 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. 1 17.5) 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 hydrobromic acid 
from the trans-, as well as from the cis-, dipentene dihydrobromide. 

Monobromodipentene dihydrobromide, C 10 H 17 Br 3 (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 cc. 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 1 ). 

Baeyer 2 obtained the same tribromide by the addition of hydro- 
bromic acid to terpinolene dibromide. 

"Wallach, Ann. Chem., 264, 25. 
"Baeyer, Ber., 27, 450. 



TETRABROMIDE. 93 

If fifty grams of the tribroniide are warmed with a solution of 
twelve grams of sodium is one hundred and fifty cc. of alcohol, 
an unsaturated hydrocarbon, C 10 H 14 , isomeric with cymene, results ; 
it boils at 183 to 184, has the specific gravity of 0.863 at 20, 
the refractive index, n^, == 1.49693, and the molecular refraction, 
45.435 (Wallach 1 ). 

Tetrabromide, 1 C 10 H 14 Br 4 . The above-mentioned hydrocarbon, 
C 10 H 14 , 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 10 H 14 Br 4 , 
separates from ethyl acetate in asymmetric crystals, which melt at 
154 to 155. 

A readily soluble bromide, C 10 H 14 Br 4 (or C 10 H ]6 Br 4 ?), melting 
at 103 to 104, is formed as a by-product during the bromination 
of the hydrocarbon, C 10 H 14 . 

Baeyer 2 found that by reducing the above-described tribroraide, 
C 10 H 17 Br 3 , melting point 110, with zinc dust and glacial acetic 
acid, the mixture being well cooled, the liquid acetate of a crystal- 
line alcohol, C 10 H 17 OH, melting at 69 to 70, is formed. In ac- 
cordance with Baeyer's proposed nomenclature, this alcohol is 
called J 4(8)-terpen (l)-ol: 




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 zinc dust in an alcoholic solution, the bromide, C 10 H 17 Br (1- 
bromo-J (8)-terpene), corresponding to the terpenol above men- 
tioned, is formed. It melts at 34 to 35, and yields a blue nitro- 
sobromide, which melts at 44 (Baeyer and Blau 3 ). 

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

*Baeyer, Ber., 27, 444. 

3 Baeyer and Blau, Ber., 28, 2290. 



94 THE TERPENES. 

Dipentene dihydriodide, C 10 H 16 -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 alcohol, and recrystallized from petroleum ether (Wallach 
and Brass 1 ). 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 2 ). It may further be obtained from pinene, limonene, 
dipentene and terpineol by methods analogous to those for the 
preparation of the dihydrochloride and dihydrobromide. 3 

When recrystallized from petroleum ether, dipentene dihydrio- 
dide exhibits two different crystalline forms ; it sometimes crystal- 
lizes in rhombic prisms, melting point 77, often in monoclinic 
tablets melting at 78 to 79 (Hintze 4 ). 

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 a similar manner. Wallach 5 
found, however, that this conjecture was not confirmed ; moreover, 
he showed that both crystallographically 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. 6 

Dipentene tetrabromide, 7 C 10 H 16 Br 4 , 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 

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

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

sWallach, Ann. Chem., 239, 13. 

*Hintze, Ann. Chem., 239, 14. 

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

Wallach, Ann. Chem., 281, 243. 

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



DIPENTENE NITROSOCHLORIDES. 95 

Wallach's investigations. It should also be mentioned that, 
almost simultaneous with Wallach, Renard 1 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 2 ). 

According to Baeyer, 3 dipentene tetrabromide is formed indi- 
rectly from terpineol. Terpineol (m. p. 35) is first converted 
into its liquid dibromide, 4 and this in turn is changed into a liquid 
1, 2, 4-tribromoterpane, C 10 H 17 Br 3 , 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 
crystals of dipentene tetrabromide measured by Hintze. 2 

It should, however, be mentioned that Hintze 4 has intimated 
that this identity does not appear to have been definitely proved 
by Villiger's results. On the other hand, Wallach 9 confirmed 
Baeyer's statement that dipentene tetrabromide results by the 
action of bromine on 1, 2, 4-tribromoterpane. 

The products 6 obtained by the action of alcoholic potash on 
dipentene tetrabromide have not yet been carefully investi- 
gated. 

Dipentene nitrosochlorides, C 10 H 16 NOC1, 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. /9-Dipentene nitrosochlo- 
ride has not been isolated in a condition of purity ; it is very read- 
ily soluble (Wallach 7 ). 

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

*Hintze, Ann. Chem., 227, 279. 

sBaeyer, Ber., 27, 439. 

*Hintze, Ann. Chem., 279, 363. 

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

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

'Wallach, Ann. Chem., 252, 124; 270, 175; 245, 268. 



96 THE TERPENES. 

When dipentene nitrosochloride is warmed with alcoholic pot- 
ash, inactive carvoxime, 1 melting point 93, is formed. 
Benzoyl dipentene nitrosochloride, 2 



\NOCOC e H 5 

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 10 H 16 -NO(ONO 2 ), is prepared by 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 of 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 3 ). 

DIPENTENE NITROLAMINES. 

The dipeutene 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 4 ). 

a-Dipentene nitrolpiperidide, 



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. 

< /?-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 

I6 \NHC 6 H 5 

results by the union of the limonene bases, melting point 112 
to 113. It melts at 125 to 126. 

JWallach, Ann. Chem., 245, 268. 
*Wallach, Ann. Chem., 270, 177. 
"Wallach, Ann. Chem., 245, 270. 
'Wallach, Ann. Chem., 252, 123; 270, 180. 



HYDROCHLORODIPENTENE NITROLANILIDE. 97 

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

/NO 

CTT / 
i n fl i R\ 



is more difficultly soluble than the corresponding limonene deriva- 
tive. It melts at 147 with decomposition. 

Nitroso-dipentene-/9-nitrolanilide is very easily soluble, and melts 
at 129. 

a-Dipentene nitrolbenzylamine, 



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 JO H 17 C1NO(NHC 6 H ? ), melting at 78 and 
resulting by the addition of hydrochloric acid to dextro- and 
levo-/3-limonene nitrolanilide in a methyl alcohol solution, com- 
bine and yield a substance, 1 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 , 2 

NO 



is almost insoluble in cold alcohol, and melts"at 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 

'Wallach, Ann. Chem., 270, 188. 
zWallach, Ann. Chem., 270, 195; 2^5, 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 /9-dipentene nitrolani- 
lides, but whether they are identical with the latter compounds 
has not yet been determined. 

Hydrochlorodipentene nitrolbenzylamine, 1 - 

/NO 
C 10 H 17 C1< 

X NHCH 2 C 6 H 5 

is almost insoluble in cold alcohol and is sparingly soluble in all 
other solvents. It melts at 150. 

Hydrochlorodipentene nitrol-p-tol uidide, 

/NO 

C 10 H 17 C1< 
^ 



was represented by Wallach 2 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. 3 
According to Wallach, dimethyl aniline acts only in the elimina- 
tion of hydrochloric acid, while the ONO 2 -group appears to be 
replaced by the ethoxyl- or methoxyl-group. 

The compound, 

/NO 
C^H^NO-jOl = C 10 H 17 C1< 

X)C 2 H 6 

forms splendid crystals, which melt at 114 to 115. 
The compound, 

/NO 
C 11 H 20 N0 2 C1 = C 10 H 17 C1< 

X OCH, 

crystallizes in prisms, melting at 139. 

A condensation-product, 11 C n H 18 O, is formed by heating an alco- 
holic solution of dipentene and paraformaldehyde in a sealed tube 

iWallach, Ann. Chem., 270, 193. 
zWallach, Ann. Chem., 245, 263. 
'Wallach, Ann. Chem., 245, 265. 
*0. 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 1 in Swedish turpen- 
tine oil ; Wallach 2 confirmed this observation, and at the same 
time found sylvestrene to occur in Russian turpentine oil. Aschan 
and Hjelt 3 further recognized it in the products of the distillation 
of pine roots, and Bertram and Walbaum 4 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 is employed. 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 5 ). 

Pure sylvestrene is obtained by heating the dihydrochloride 
with an equal weight of aniline 6 and a small quantity of alcohol 
(Atterberg 1 ), 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. 5 The hydro- 
carbon is distilled with steam, heated with a potassium hydroxide 
solution, again distilled with steam, and fractionated. 

i Atterberg, Ber., 10, 1202. 

zWallach, Ann. Chem., 230, 240 and 247. 

sAsehan and Hjelt, Chem. Ztg., 18, 1566. 

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

6 Wallach, Ann. Chem., 239, 24. 

sWallach, Ann. Chem., 2^7, 197. 



100 



THE TERPENES. 







o 


i 


? >r pc .-* 




"5 

o 


H? ^ "S 


_i'^ 


Sg, o . 


'si *t*tf3 s 


c 
fc 


_^ 

3 


cf i 'S 


o ^ 

o ^ 


! - h? 1 Pn 


O 


V 

a 


5 ^ r 


. -S 




SYLVESTRENE DIHYDROBROMIDE. 101 

PROPERTIES. 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 c = 1.47468. 1 Another specimen boiled at 175 to 176, and 
at 20 had the sp. gr. of 0.848 and the refractive index, 
n^ = 1.47573. 2 Sylvestrene is optically dextrorotatory. The 
specimen above referred to had the specific rotatory power, 
{Vj^ + 66.32 . 2 

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 3 ). 

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 10 H 16 -2HC1. 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. 3 

Sylvestrene dihydrochloride crystallizes in monosymmetric 
tablets, which melt at 72 and have a specific rotatory power, 
\a\ D = +18.99 02 . 

Sylvestrene dihydrobromide, 4 C 10 H 16 - 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, 2 []j,= -f 17.89. 

Sylvestrene dihydriodide, 4 C l() H 16 . 2HI, is prepared like the two 



'Wallach and Pulfrich, Ann. Chem., 245, 197. 
2 Wallach and Conrady, Ann. Chem., 252, 149. 
'Wallach, 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, 1 C 10 H 16 Br 4 . 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] 1) = + 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 16 NOC1, is prepared from 
pure sylvestrene, obtained from its dihydrochloride, by the follow- 
ing method. To a well cooled mixture of four cc. of the terpene 
and six cc. of amyl nitrite, four cc. or five cc. 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 2 ). 

Sylvestrene nitrolbenzylamine, 



is obtained by warming an alcoholic solution of sylvestrene nitro- 
sochloride with benzylamine (Wallach 3 ). The base separates from 
methyl alcohol in well defined crystals, melting at 71 to 72. It 
has a specific rotatory power, [a\ D = -f 185.6, while that of its 
hydrochloride is []/>= -f 79. 2. 4 

JWallach, Ann. Chem., 239, 28. 

sWallach, Ann. Chem., 245, 272. 

Wallach, Ann. Chem., 252, 135. 

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






CARVESTKENE. 103 

According to Baeyer, 1 sylvestrene may be converted into meta- 
cymene 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 zinc 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. CAEVESTRENE. 

This optically inactive terpene was obtained by Baeyer 2 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 3 obtained dihydrocarvone, C 10 H 16 O, by the oxidation 
of dihydrocarveol ; subsequently, Baeyer 4 prepared the same com- 
pound by the reduction of carvone. Dihydrocarvone is converted 
into the isomeric ketone carone, C 10 H 16 O, by the successive ad- 
dition and removal of hydrobromic acid (Baeyer 5 ). 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, 2 C 10 H 17 NH 2 , by heating with hydro- 
chloric acid. 

When vestrylamine hydrochloride 2 is distilled in an atmos- 
phere of dry hydrochloric acid gas, it decomposes into ammonium 
chloride and a hydrocarbon, C 10 H 16 , 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 ]0 H 17 NH 2 .HC1 = NH 4 C1 + C 10 H 16 . 

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

'Baeyer and Villiger, Ber., 31, 2067. 

"Baeyer, Ber., 27, 3485. 

sWallach, Ann. Chem., 275, 115; 219, 378. 

*Baeyer, Ber., 26, 823. 

sBaeyer, 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 to a 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. 1 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 the cold. 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, 2 the crude carvestrene, boiling at 180 
to 180, 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 10 H 16 2HC1, 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 10 H 16 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. 
sSemmler, Ber., 84, 708. 



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 1 has also succeeded in converting carvestrene into meta- 
cymene by the bromination of carvestrene dihydrobromide, and 
subsequent reduction with zinc 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 2 in 1885. He showed that when 
turpentine oil is heated with alcoholic sulphuric acid, according 
to Flawitzky's 3 method, a terpene is formed, which had hitherto 
been overlooked. According to further observations 4 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 5 
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. 6 

According to Baeyer, 7 terpinolene is formed from the tribro- 
mide, C 10 H 17 Br 3 (m. p. 110), which is derived from dipentene 
dihydrobromide by bromination. This tribromide is converted 
into the acetate of J-4(8)-terpen-l-ol, an alcohol melting at 69 

iBaeyer and Villiger, Ber., SI, 1402. 

'Wallach, Ann. Chem., 227, 283; 230, 262. 

sFlawitzky, Ber., 12, 1022. 

'Wallach, Ann. Chem., 239, 23. 

sWallach and Kerkhoff, Ann. Chem., 275, 106. 

Wallach, Ann. Chem., 291, 342. 

'Baeyer, Ber., 27, 436. 



106 



THE TERPENES. 



to 70, by the action of zinc dust and glacial acetic acid, and when 
this acetate is distilled with quinoline, terpinolene results : 

C ]0 H 17 OCOCH S CH 3 COOH = C 10 H 16 . 
Baeyer expresses these transformations by the following formulas: 




A Br 

H 3 C CH 3 
Tribromide (m. p. 110). 




H,C CH 3 

A*( g )-Terpen-l-ol acetate. 




H $ C CH 3 
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. 1 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 zinc 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. 

iWallach and Kerkhoff, Ann. Chem., 275, 106; Baeyer, Ber., 27, 448. 



TERPINOLENE TETRABROMIDE. 



107 



According to Wallach, 1 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. 1 

Terpinolene dibromide, C 10 H 16 Br 2 . Baeyer 2 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 J-4-(8)-terpen-l-ol acetate, melting at 82 
(Baeyer 2 ). 

Terpinolene tetrabromide, C 10 H 16 Br 4 , was first prepared by Wal- 
lach by brominating terpinolene in a glacial acetic acid solution at a 
low temperature. 3 According to Baeyer and Villiger, 4 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, 5 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. 

1 Wallach, Ann. Chem., 239, 23. 

2 Baeyer, Ber., 27, 447 and 448. 

"Wallach, Ann. Chem., 227, 283; 230, 263; 239, 23; 275, 107. 

'Baeyer and Villiger, Ber., 27, 448. 

Hintze, Ann. Chem., 230, 263. 



108 THE TERPEXES. 

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, 1 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 2 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, 3 who further showed 
that phellandrene occurs in the oil of elemi, 4 and that these three 
oils contain dextro-phellandrene whose nitrosite is levorotatcry. 
Levo-phellandrene was afterwards discovered by Wallach and 
Gildemeister 5 in eucalyptus oil {Eucalyptus amygdalina} ; its 
nitrosite rotates the plane of polarization to the right. Bertram 
and Walbaum 6 found levo-phellandrene in the pine needle oils 
from Pinus montana and Picea exeelsa, while Power and Kleber 7 
proved its presence in bay oil. According to Wallach and Rhein- 
dorf, 8 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- 

1 Pesci, Gazz. Chim., 16, 225. 

2 Cahours, Ann. Chem., 41, 74 ; compare Bunge, Zeitschr. Chem., 1869, 579 ; 
Chiozza, Gerhardt's Lehrb., German edition, 3, 394. 

HVallach, Ann. Chem., 239, 40. 

*Wallach, Ann. Chem., 246, 233. 

6 Wallach and Gildemeister, Ann. Chem., 246, 282 and 233. 

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

7 Power and Kleber, Pharm. Rundschau, .7895, No. 13; compare Schimmel's 
Semi-Annual Report, April, 1895, 13; see also Pharm. Review, 1896. 

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



PHELLANDRENE NITROSITE. 109 

carbon are fractionated in a vacuum 1 since it is partially de- 
composed by distillation at ordinary pressure. 

PROPERTIES. 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 2 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\ D = + 17.64. 

Wallach 4 found that phellandrene from an Australian euca- 
lyptus oil boiled at 65 (12 mm.), had the sp. gr. 0.8465 and re- 
fractive index, n^ = 1.488, at 19. Gildemeister and Stephan 5 
found the optical rotation of phellandrene from schinus oil to be 
[]= + 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 5 ). 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 l is an oil, and is probably a mixture. 
It yields considerable cymene by boiling with alcoholic potash. 

Phellandrene nitrosite, 6 C ]0 H, 6 -N 2 O 3 , 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 cc. 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. 

tWallach and Herbig, Ann. Chem., 287, 371. 

*Pesci, Gazz. Chim., 16, 225; Ber., 19, 874, Ref. 

3 Gildemeister and Stephan, Arch. Pharm., 235, 591. 

'Wallach, Ann. Chem., 287, 383. 

sWallach, Ann. Chem., 239, 43. 

6 Wallach and Gildemeister, Ann. Chem., 246, 282. 



110 THE TERPENES. 

Bertram and Walbaum l 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. 2 

The nitrosite prepared from dextro-phellandrene is optically 
levorotatory ; Pesci 3 found its specific rotatory power, [a] D = 
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 4 is ob- 
tained, which is identical in all other properties with the two 
active derivatives. 

According to a more recent investigation by Schreiner, 5 crude 
phellandrene nitrosite, prepared from a levorotatory fraction of 
an eucalyptus oil containing phellandrene, has the rotatory power, 
[a] /) = -f 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, []# 
= -f 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, \fi\ D 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, 3 
phellandrene nitrosite yields phellandrene diamine, C 10 H 16 (NH 2 ) 2 , 
by reduction with nascent hydrogen, and it is, therefore, to be 
considered as having the formula, 

,NO 



'Bertram and Walbaum, Arch. Pharm., 231, 298. 

2 Wallach and Herbig, Ann. Chem., 287, 371. 

sPesci, Gazz. Chim., 16, 225; Ber., 19, 874, Ref. 

Wallach, Ann. Chem., 246, 235. 

5 O. Schreiner, Pharm. Arch., 1901, 4> 90; compare Gildemeister and 
Stephan, Arch. Pharm., 235, 591 ; Schimmel & Co., Semi- Annual Report, 
October, 1901, 62. 






-, 



PHELLANDRENE NITROSITE. Ill 

By the action of ammonia on the nitrosite Pesci obtained a sub- 
stance having acid properties, which has the empirical constitution, 
C 1() H 17 N 3 O 4 , and crystallizes in needles. Nitrophellandrene, C 10 - 
H 15 NO 2 , 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 10 H 15 NH 2 , on reduction. 

According to Wallach, 1 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 7 H ]2 O 4 , together with a neutral compound, C 7 H 10 - 
O 4 N 2 ; the latter substance melts at 88 to 89, and gives the 
Liebermann reaction for nitroso-compounds. The acid, C 7 H 12 O 4 , 
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. 2 
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 10 H 15 NO 2 , 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 10 H 19 OH. 

2. Optically active tetrahydrocarvone, C 10 H 18 O. 

3. Optically active tetrahydrocarvylamine, C 10 H 19 NH 2 . 

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. 

J Wa]lach, Ann. Chem., 313, 345. 

2 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, 1 
however, recognized it as a definite terpene, and Wallach 2 and 
Weber 3 distinctly characterized it by its transformation into ter- 
pinene nitrosite. Weber 3 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. 4 

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 5 and phellan- 
drene 6 with dilute or alcoholic sulphuric acid ; it is also obtained 
by boiling terpine hydrate, 1 cineole, 7 terpineol 8 or dihydrocarveol 9 
with dilute or alcoholic sulphuric acid. The transformation of 
dihydrocarvylamine, C 10 H ]r NH 2 , an amine corresponding to the 
alcohol, dihydrocarveol, into terpinene is of special interest. By 
the dry distillation of dihydrocarvylamine hydrochloride, Wal- 
lach 10 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 u 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 j 
hence it forms a constituent of the oil which Armstrong and 
Tilden 12 formerly designated " terpUene" 

'Wallach, Ann. Chem., 280, 254 and 260. 

*Wallach, Ann. Chem., 239, 33. 

3Er. Weber, Ann. Chem., 238, 107. 

*W. Biltz (Ber., 32, 995), finds that the fractions, boiling at 77 to 81 at 
30 mm. pressure, of the crude oil of Origanum majorana consist largely of 
terpinene, which was identified by the formation of the nitrosite. 

^Wallach, Ann. Chem., 239, 15. 

eWallach, Ann. Chem., 239, 43. 

'Wallach, Ann. Chem., 239, 22. 

sWallach and Kerkhoff, Ann. Chem., 275, 106. 

BWallach, Ann. Chem., 275, 113. 

"Wallach, Ann. Chem., 275, 125. 

''Bertram and Walbaum, Journ. pr. Chem. [2], ^5, 601. 

"Armstrong 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 a time, 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 1 ). 

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. 2 

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 
nitrosite, and contains no other terpene than terpinene (Wal- 
lach 3 ). 

It is 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 

Wallach, Ann. Chem., 239, 35. 

*Tilden and Williamson, Journ. Chem. Soc., 63 (1893), 295. 

Wallach, Ann. Chem., 239, 38. 



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 1 ). 

According to Semmler, 2 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- 
pineue 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 3 ). 

Terpinene nitrosite, 

/NO 
C IO H :6 < 

\)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 3 ). 

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 

ifiaeyer, Ber., 27, 815. 
"Semmler, Ber., 34, 708. 
sWallach, Ann. Chem., 239, 38. 






TEKPINEKE NITEOSITE. 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 1 ). 

Terpinene nitrosite l is very easily soluble in warm alcohol, 
ether and ethyl acetate, difficultly in petroleum ether, and sepa- 
rates from alcohol in snow-white, monoclinic 2 crystals, which melt 
at 155. Its solutions are optically inactive. 

According to Wallach, 1 its solutions do not decolorize bromine, 
so that it behaves as a saturated compound ; more recent investi- 
gations by Semmler 3 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 recry stall ized 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, 3 C 10 H 14 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 10 H 15 O-NH 2 , 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, 4 C 10 H 17 NH 2 . 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, 3 melting at 88. 

3. p-Cymene. 4 

4. A hydrocarbon, 3 C 9 H 14 , boiling at 160 to 164. 

When terpinene nitrosite is reduced in an alcoholic solution 

'Wallach, Ann. Chem., 239, 35. 
sffintze, Ann. Chem., 241, 315. 
sSemmler, Ber., 34, 708. 
Wallach, 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 : 



C in H 



I. II. 

/N=O xN O H 

18 < and C 10 H 15 f 

\0 N = \0 N = 



Briihl l and Semmler 2 favor the second formula, which repre- 
sents the nitrosite as an isonitroso-com pound. Wallach, 3 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 nitrolethylaraine 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, 3 



13 \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 : 



xNOH 
C 10 H )6 NO.ONO + NH S = C 10 H 15 



HNO 2 



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 



!Bruhl, Ber., 21, 175. 
s Semmler, Ber., 84, 713. 
'Wallach, Ann. Chem., 24o, 274. 



TEEPINES NITROLDIMETHYLAMINE. 117 

to the action of the free nitrous acid, and the reaction-product is 
completely decomposed. 
Terpinene nitrolamine, 1 



H 

H 



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 
cc. 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 1 obtained the dibenzoyl derivative 
of this base by the Baumann-Schotten method ; it melts at 146. 

For the preparation of substituted terpinene nitrolamines, 
Wallach 2 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, 



lois 

\NHCHj 

crystallizes in splendid prisms, which melt at 141. 
Terpinene nitroldimetnylamine, 

C H / N H 

\N(CH,}, 

Wallach, Ann. Chem., 2^1, 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, 



C H 

Cl Hl 

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, 



melts at 117 to 118. 
Terpinene nitrolamylamine, 

C H 
C " H 

is characterized by its splendid power of crystallization. It dis 
solves sparingly in alcohol and ether, and melts at 118 to 119. 
Terpinene nitrolpiperidide, 



is quite insoluble in sodium hydroxide ; it forms splendid crystals, 
which melt at 153 to 154. 
Terpinene nitrolbenzylamine, 1 

xNOH 

QHM^ 

\NHCH 2 C 6 H 5 

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. 

i Wallach, Ann. Chem., 252, 134. 






TERPENE FROM INDIAN HEMP. 119 

According to Semmler, 1 tanacetene boils at 60 to 63 under 
14 mm. pressure, has the sp. gr. 0.8508 and refractive index, 
n^ = 1.476, at 20. It contains two ethylene linkages. 

According to Wallach, 2 thujene boils at 170 to 172, has the 
sp. gr. 0.836 and refractive power, n^ = 1.47145, at 22. 

In a more recent publication, Tschugaeff 3 states that thujyl 
alcohol, C 10 H 17 OH, may be converted into a methyl xanthate, and 
that when this compound is dry distilled it yields a new terpene, 
C 10 H 16 ; the latter boils at 151 to 152.5, has a sp. gr. 0.8275 at 
20/4, and the refractive index, n^, = 1.45042, 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 crystalline 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 "wothujene" 
(Tschugaeff). 

By the dry distillation of trimethyl thujylammonium hydroxide, 
C 10 H 17 N(CH 3 ) 3 OH, Tschugaeff 4 obtained a thujene which boils 
at 151 to 153, has a sp. gr. 0.8263 at 20/4, refractive index, 
n ? = 1.45022, at 20, and a rotatory power, \a\ D = 8.23. 
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 10 H 16 O, gives rise to two stereoisomeric thujyl 
alcohols, C 10 H 17 OH, on reduction, and these yield two stereo- 
isomeric thujenes. 

A dextrorotatory thujene 4 ([]/> =+ 21.83 in a ten cm. 
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. 5 It has the composition, C 10 H 16 , boils 

i Semmler, Ber., 25, 3345. 

zWallach, Ann. Chem., 286, 97. 

"Tschugaeff, Ber., 33, 3118. 

'Tschugaeff, Ber., 3J h 2276. 

5 Wood, 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 ]0 H 16 , which may possibly prove to be the first 
representative of the class of orAo-terpenes, was obtained by 
Wailach l during his investigation of synthetical (or^Ao-?) pule- 
gone, C 10 H 16 O. 

By reducing synthetical pulegone with sodium and alcohol, 
pulegol, C 10 H 17 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 lirnonene and of terpinolene; it boils at 173 to 
175, has the specific gravity 0.823 and refractive index, n D = 
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. 

13. FENCHELENE. 

This terpene 2 is produced as a by-product in the formation of 
fencholenyl alcohol, C 10 H I7 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, n^, = 
1.47439, at 20. 

14. EUTERPENE. 

This terpene 3 is formed when dihydroeucarveol, C 10 H 17 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 to 165. It yields 
acetic, oxalic, and ^e?n-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 zinc 
and alcoholic hydrochloric acid and finally with sodium and 
alcohol, yields 1.2.4--dimdhyl-dhyl-benzene, boiling at 185 to 
191. 

i Wailach, Ber., 29, 2957. 
nVallach, Ann. Chem., 300, 294. 
Baeyer and Villiger, Ber., 31, 2067. 



SABINENE GLYCOL. 121 



15. TRICYCLENE. 

This hydrocarbon was obtained by Wagner 1 by treating pinene 
dibromide, C 10 H 16 Br 2 (m. p. 169 to 170), with zinc dust and 
acetic acid. It has the composition, C 10 H 16 , 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 frae- 
tionation. This hydrocarbon, C 10 H 16 , which Wagner 2 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 10 H 16 , which Semmler 3 calls sabinene. 

It has a specific gravity 0.840, a refractive index, fJL D = 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 10 H ]6 (OH) 2 , 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 

'Godlewski and G. Wagner, Chem. Centr., 1897 (I.), 1055; Journ. Russ. 
Chem. Soc., 29, 121. 

G. Wagner and Brykner, Ber., S3, 2121. 
8 F. Semmler, Ber., 83, 1455; 34, 708. 



122 



THE TERPENES. 



melts at 54. It has the specific gravity, 1.021, the refractive 
index, fJ. D = 1.402, and a molecular refraction, M = 47.41. 

Dihydrocuminyl alcohol, C 10 H 15 OH, is produced by warming 
the glycol with acidified water; it boils at 242, has a sp. gr. 
0.9572,^=1.5018, and M= 46.80. Chromic acid oxidizes it 
to cuminyl alcohol and cumin aldehyde. 

Sabinenic acid, C 10 H 16 O 3 , 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 10 H 12 O 2 (m. p. 117 to 118). 

Sabinene, sabinene glycol and sabinenic acid are all dextro- 
rotatory. 

Sabinene ketone, C 9 H 14 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, H D = 1.4629, and a molecular refrac- 
tion, M= 40.26. Its semicarbazone crystallizes from alcohol, and 
melts at 135 to 137. The ketone is levorotatory, []= 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 

/ 

Campliene 



Borneo] 
C 10 H 17 OH 



1 1 

I 1 



-> Dipentene 



Terpinene^ 



Terpinolene 



[Lii 

\ 


no 


nc 


nc 


] 


>. ) 








^ i 


C 10 H 18 (OH) 2 

1 t 

Y 1 














Terpineol -< 












,C 10 H 17 OH - 








1 








Cineole 







HYDROCARBONS, C 10 H 18 . 
1. DIHYDROCAMPHENE, C 10 H 18 . 

Baeyer 1 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 bornyl iodide, C 10 H 17 L 

Bredt and v. Rosenberg 2 obtained dihydrocamphene by the 
reduction of pinene hydrochloride and of bornyl chloride with 
sodium and alcohol. 

Armstrong 3 speaks of dihydrocamphene under the term camp- 
hydrene, and he mentions its preparation from pinene hydrochloride 
by the action of sodium. 

Semmler 4 has also recently prepared this hydrocarbon by the 
reduction of pinene hydrochloride, pinene dibromide, camphene 
hydrochloride, and camphene dibromide with sodium and alcohol. 

Dihydrocamphene 6 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 6 describes a compound, C 10 H 18 , 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 10 H 18 , is also called camphane by 
Forster 7 in a paper entitled, "Studies in the Camphane Series"; 
thus, the compound C 10 H 1(5 BrNO 2 , which is obtained from cam- 
phoroxime, is called bromonitrocamphane, and the compound, 
C 10 H 17 NO 2 , nitrocamphane, etc. 

It may be mentioned that a hydrocarbon, C 20 H 34 , termed dihy- 
drodicamphene, 8 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. 

'Baeyer, Ber., 26, 826. 
z Private communication to Dr. Heusler. 
3 Armstrong, Journ. Chem. Soc., 69 (1896), 1398. 
F. Semmler, Ber., 33, 774 and 3420. 
5 Bredt and v. Rosenberg. 
6 0. Aschan, Ber., 33, 1006. 

7 M. O. Forster, Journ. Chem. Soc., 77 (1900), 251. 
8 Etard and Meker, Compt. rend., 126, 526. 

123 



124 



THE TERPENES. 



2. ISODIHYDROCAMPHENE, C 10 H 18 . 

According to Semmler, 1 when isoborneol is heated with zinc 
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 10 H 18 ; 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. 

3. CARVOMENTHENE, C 10 H 18 . 

By the separation of the elements of water from carvomenthol 
(tetrahydrocarveol), C 10 H 19 OH, it may be converted into a hydro- 
carbon, C 10 H, 8 , which differs from menthene, C 10 H 18 , 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 III. (Baeyer). 



CHOH 





Carvomenthol 
( tetrahydrocarveol ) . 



H,C CH 3 
Menthol. 




H,C 





H,c OH 



in. 



H 3 C CH, 
Carvomenthene. 
F. Semmler, Ber., 33, 774. 




Menthene. 






CARVOMENTHENE HYDROBROMIDE. 125 

Baeyer l prepared carvomenthene by treating tetrahydrocarveol 
(carvomenthol) with hydrobromic acid, and distilling the result- 
ant bromide with quinoline, while Wallach 2 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 (corr.). 

According to more recent investigations by Kondakoff and 
Lutschinin, 3 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, n^, = 1.45979, a molecular refraction, Jf = 45.68, and a 
specific rotation, [a\ D = 2 4'. The higher boiling fraction 
has the sp. gr. of 0.8230 at 19/4, an index of refraction, 
n^, = 1.46108, a molecular refraction, M = 45.89, and a specific 
rotatory power, [a\ D = 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 carvomeuthol. (See ter- 
tiary carvomenthol.) 

Carvomenthene hydrochloride, C 10 H I8 -HC1, 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 
n D = 1.464941, a molecular refraction, M= 50.95, and a specific 
rotatory power, [] = 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 10 H lg -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, n^^ 
1.48822, at 20.5, a molecular refraction, M= 54.27, and it is 
optically inactive. Its properties are almost identical with those 
of carvomenthyl bromide, but it seems probable that it consists of 

'Baeyer, Ber., 26, 824. 

'Wallach, Ann. Chem., 277, 130. 

3 Kondakoff and Lutschinin, Joiirn. pr. Chem., 60 (II.), 257. 



126 THE TERPENES. 

a mixture of secondary and tertiary bromine derivatives, which 
are derived from two isomeric carvomentheues 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 D = 1.45959, a molecular refraction, M = 45.69, 
and a specific rotatory power, [a]^= 23' (Kondakoff and 
Lutschinin). 

4. MENTHENE, C 10 H 18 . 

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, 1 it is prepared by boiling menthol with 
fused zinc chloride or anhydrous copper sulphate, while Sicker 
and Kremers 2 obtain it by heating menthol with twice its weight 
of acid potassium sulphate at 180 to 200. For its preparation, 
Wagner 3 recommends the method that Wallach gives for the 
preparation of camphene from borneol ; thus, menthol is converted 
into menthyl chloride, C 10 H 19 C1, 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, 4 mentheue 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 5 by heating with a solution of potassium phenolate 
for twelve minutes at 150. Menthol may be directly converted 
into menthene 6 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 Tschugaeif, 7 a menthene of very high rotatory 
power is obtained by the distillation of the methyl ester of men- 
ihylxanthogenic acid ; the latter compound is produced by treat- 

i Briihl, Ber., 25, 142. 

2 Sicker and Kremers, Ammer. Chem. Journ., 14, 291. 

sWagner, Ber., 27, 1636. 

*Berkenheim, Ber., 25, 686. 

sMasson and Reychler, Ber., 29, 1843. 

eKonowaloff, Journ. Russ. Phys. Chem. Soc., 32 (1900), 76. 

'Tschugaeff, 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] D = 
111.56 to 116.06. 

Andres and Andreef x state that the fraction boiling between 
160 and 170 of peppermint oil consists of a mixture of a 
terpene, C 10 H 16 , with a hydrocarbon, C 10 H 18 . 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 Labbe", 2 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 Briihl 3 gives the sp. gr. 0.8064 at 20. 
Briihl has also determined other physical constants of menthene. 
It is optically dextrorotatory, [] /) = -f 32.77 (Urban & Krem- 
ers 4 ). Masson and Reychler 5 appear to have prepared a levo- 
rotatory menthene from menthyl chloride, and they give its spe- 
cific rotatory power, [a] D = 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 5 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). 

'Andres and Andreef, Ber., 25, 609. 
*H. Labb6, Bull. Soc. Chim., 19 (1898, III.), 1009. 
'Briihl, Ber., 25, 151. 

'Urban and Kremers, Ammer. Chem. Journ., 16, 395; Proc. Ammer. 
Pharm. Assoc., 1892, 273; 1893, 185. 
5 Masson and Reychler, Ber., 29, 1843. 



128 THE TERPENES. 

It combines with bromine producing an oil. Briihl 1 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. 1 

Menthene nitrosochloride, C 10 H 18 - NOC1, has been investigated 
by Kremers 3 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, [a] /) = 
2.4508, while the other nitrosochlorides are inactive or dextro- 
rotatory, [] z> = + 1.015 to -f 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 4 obtained 
an inactive nitrosochloride, melting at 128, and that Baeyer 5 has 
mentioned a menthene nitrosochloride, melting at 146. Tschu- 
gaeff 6 has also prepared a nitrosochloride, melting at 127 and 
having [a],, = 242.5. 

Menthene nitrosate, C 10 H 18 -N 2 O 4 , melts at 98, and is optically 
inactive (Urban and Kremers). 

Menthene nitrolbenzylamine, 



. CH 2 . C,H 5 

is prepared in the usual manner from the nitrosochloride or nitro- 
sate. It is optically inactive, and melts at 105.5 to 107. Ac- 

iBriihl, Ber., 25, 151. 

"Wagner, 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; Bichtmann and Kremers, Amer. Chem. 
Journ., .78, 762. 

<Urban and Kremers, Amer. Chem. Journ., /fi, 395. 

sBaeyer, Ber., 26, 2561. 

sTschugaeff, Ber., 82, 3332. 



NITROSOMENTHENE. 129 

cording to Bichtmann 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, 1 C 10 H 16 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 10 H 17 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 10 H 16 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 2 and Tolloczko. 3 According to Wagner, 
the following products are obtained by oxidizing menthene at 
about with a one per cent, solution of permanganate. 

1. Menthene glycol, C 10 H 18 (OH) 2 . 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 10 H 16 , when treated with 
acetic anhydride. 

2. Eetone alcohol, C 10 H 17 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 17 H 23 O 3 N, melting at 157, and an oxime, C 10 H ]9 O 2 N, which 
crystallizes from ether in microscopic tablets, melting at 132 to 
133. 

3. Acetic acid, methyl adipic acid, and 7'-isobutyryl-/?-methyl 
valeric acid (oxymenthylic acid). These acids are also formed 
in the oxidation of menthone with potassium permanganate. 

'Urban and Kremers, and Richtmann and Kremers. 

*Wagner, Ber., 27, 1636. 

s Tolloczko, Ber., 28, 926, Ref. 

9 



130 THE TERPENES. 

Meta-menthene (1 : 3-methyl-isopropyl-cycloliexene), C )0 H 18 , is 
a hydrocarbon, which has been prepared by Knoevenagel l by 
heating cis-syta metrical menthol with phosphoric anhydride at 
110 to 130. It is a 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, n^ = 1.45609, and the 
molecular refraction, R = 45.67. 

According to Kondakoff, 2 a hydrocarbon, C 10 H 18 , 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 10 H 18 , will be described under linalolene. 



HYDROCARBONS, C^H^. 

Many members of the terpene series are converted into hydro- 
carbons, C IO H 20 , 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 3 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 D = 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 4 by the direct hydra- 
tion of oil of turpentine should in all probability be regarded as 
tetrahydropinene. 

Knoevenagel and Wiedermann, Ann. Chem., 297, 169. 
2 Kondakoff, Journ. pr. Chem., 54, 433. 
sWallach and Berkenheim, Ann. Chem., 268, 225. 
*Orlow, Ber., 16, 799. 






META-MENTHANE. 131 

Tetrahydrofenchene, C 10 H 20 , was obtained by Wallach l 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 0.81 14 at 15. 

A hydrocarbon, C 10 H 20 , is obtained by the reduction of terpine 
hydrate; it boils at 168 to 170, and has the specific gravity 
0.797 at 15 (Schtschukarew 2 ). 

The hydrocarbon, C 10 H 20 , prepared by Wagner 3 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 4 as menthonaphthene. According to Wagner, it boils at 1 68 
to 169, and has the sp. gr. 0.8066 at ; according to Berken- 
heim, it boils at 169 to 170.5, and has the specific gravity 
0.8067 at and 0.796 at 15. 

Jiinger and Klages 5 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 6 (1 : 3-methyl-isopropylcyclohexane), C 10 H 20 , is 
prepared by the reduction of symmetrical menthyl iodide. It 
boils at 167 to 168 under a pressure of 756 mm., has a specific 
gravity 0.8033 at 14/4, refractive index, n^ = 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, C 10 H 20 , isolated by Renard 7 from the 
essence of resin by means of sulphuric acid, boils at 171 to 173, 
and has the specific gravity 0.8116 at 17. 

iWallach, Ann. Chem., 284, 326. 

* Schtschukarew, Ber., 23, 433c. 

'Wagner, Ber., 27, 1638. 

'Berkenheim, Ber., 25, 686. 

sjiinger and Klages, Ber., 29, 317. 

6 Knoevenagel and Wiedermann, Ann. Chem., 297, 169. 

7 Renard, Ann. Chim. Phys. [6], 1, 223. 



132 



THE TERPENES. 



Berkenheim l has published the results of experiments on the 
relations of the naphthenes, C 10 H 20 , occurring in Russian petroleum, 
to the hydrocarbons under consideration, and to the terpenes. 

Diethyl hexamethylene, C^H^, was synthetically prepared by 
Zelinsky and Rudewitsch. 2 According to these chemists, diethyl- 
keto-hexamethylene, C 10 H 18 O, 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 10 H 19 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 10 H ]g I, by treatment with hydriodic 
acid, and when the iodide is reduced with zinc and hydrochloric 
acid in alcoholic solution it yields diethyl hexamethylene. The 
following formulas express these reactions : 



' Coll.; 




CH 2 

Diethyl-keto-hexamethy- 
lene. 





CH 2 
Alcohol, C 10 H 19 OH. 



I H C,H 5 

2H, 

Iodide, C 10 H 18 I. 




CH 2 
Diethyl hexamethylene. 



Diethyl hexamethylene is a colorless liquid with a petroleum- 
like odor. It boils at 169 to 171, has the specific gravity, 
d 22/4 = 0.7957, and the refractive index, n D = 1.4388, at 20. 
It is a saturated hydrocarbon, and is immediately colored by bro- 
mine vapor. 



'Berkenheim, Ber., 25, 686. 

2 Zelinsky and Rudewitsch, Ber., 28, 1341. 



OXIDIZED COMPOUNDS RELATED TO THE TERPENES, 



1. SUBSTANCES WHICH CAN NOT BE REGARDED AS 
DERIVATIVES OF THE HYDROCYMENES. 



(ANALOGUES OF PINENE, GAMPHENE AND 
FENCHENE.) 

1. CAMPHOR, C 10 H 16 O. 

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 l have accomplished. They obtained cam- 
phor by the dry distillation of the calcium salt of homocamphoric 
acid, prepared from camphonitrile ; 2 accepting Bredt's formula of 
camphor (see page 25), this reaction may be expressed by the 
equation : 




2 COO 






Ca = CaCO 




H,C-C-CH 3 
)H 2 C COO- 



This synthesis of camphor 3 is quite analogous to the syntheses 
of many keto-pentamethylenes, which have been prepared by J. 
Wislicenus and his students. 

'Bredt and v. Rosenberg, Ann. Chem., 289, 1. 

2 Haller, Theses pre'sente'es a la faculty des sciences de Paris; compare 
Claisen, Ann. Chem., 281, 349. 

"A. Haller, Bull. Soc. Chim., 15, 1896 (III.), 324. 

133 



134 



THE TERPENE8. 



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] ,,= 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, l both 
of these changes involve the formation of carvenone, C 10 H 16 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. 

" Camphren " 2 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 cam phoronic acid 
(m. p. 139) ; Bredt formulates this reaction as follows : 







Camphor. 



H 2 OH COOH COOH COOH 

H.O-Q-CH, *- I H 3 C-C-CH 3 

COOH CH 2 C COOH 

H 3 CH, 

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- 

1 Bredt, Rochussen, and Monheim, Ann. Chem., 314, 369. 

2 Armstrong and Kipping, Journ. Chem. Soc., 63, 77 ; compare Bredt, Ann. 
Chem., 3H, 369. 






CAMPHOROXIME ANHYDRIDE. 135 

phor. The most important of these derivatives are camphoroxime, 
borneol, isoborneol, and substances obtained from them. 

Camphoroxime, 1 C 10 H 16 NOH, was discovered by Nageli. 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 3 prisms, 
which, like those of the active tartaric acids, are hemimorphic 
(Beckmann 4 ). 

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 phenylcyanate, 5 which melts 
at 94. 

Leuckart and Bach 6 obtained bornylamine, C 10 H 17 NH 2 , 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. 7 

Camphordioxime, see Angelico, Atti. Real. Accad. Lincei, 1900 



Camphoroxime anhydride (a-campholenonitrile), C ]0 H 15 N, was 
first prepared by Nageli 8 by the action of acetyl chloride on cam- 
phoroxime; it may also be obtained by the action of other dehy- 
drating agents 9 on camphoroxime, most readily by boiling with 
dilute sulphuric acid. 

"Forster, Journ. Chem. Soc., 71, 191 and 1030; 75, 1141; 77, 251. 

2 Nageli, Ber., 16, 497 ; see Konowaloff, Journ. Russ. Phys. Chem. Soc., SS 
(1901), 45; Auwers, Ber., 22, 605. 

sMuthmann, Ann. Chem., 250, 354. 

*Beckmann, Ann. Chem., 250, 354. 

sGoldschmidt, Ber., 22, 3104. 

6 Leuckart and Bach, Ber., 20, 104; see Konowaloff, Journ. Ruas. Phys. 
Chem. Soc., 33, 45; Forster, Journ. Chem. Soc., 73, 386. 

'Angeli 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. 

sNageli, Ber., 16, 497. 

9 Goldschmidt and Zurrer, Ber., 17, 2069 and 2717; Goldschmidt and 
Koreff, Ber., ^8, 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 2 ). 

It is an unsaturated compound and combines directly with 
halogen acids, forming oily addition-products (Wallach T ). 

By reduction with zinc and sulphuric acid, 3 or better with 
sodium and alcohol, 4 a-campholenonitrile yields a-camphylamine, 
C ]0 H 17 NH 2 . When hydrogen chloride is passed into an alcoholic 
solution of the nitrile, 6 a-campholenic add is produced, together 
with some isoamidocamphor, C 10 H 15 O NH 2 . 

a-Campholenamidoxime,C ]0 H 15 (NOH) . NH 2 , 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 9 H 15 CONH 2 , is formed, 
together with a-campholenic acid, by heating camphoroxime anhy- 
dride with alcoholic potash ; it crystallizes in leaflets, melting at 
125 (Nageli 6 ). It has the specific rotatory power, [a]j,= 
4.06. Warm, dilute sulphuric acid converts it into the sul- 
phate of isoamidocamphor, and, under certain conditions, into 
dihydrocampholenolactone, C 10 H 16 O 2 . It is quite readily changed 
into a-campholenic acid by boiling with alcoholic potash. 

a-Campholenic acid, C 9 H ]5 - COOH (Goldschmidt and Ziirrer, 7 
and Tiemann). This acid is identical with the " oxycamphor " 
obtained by Kachler and Spitzer; 8 it boils at 256, has the 
specific gravity 0.992 at 19, and the refractive index, n^ = 
1.47125, from which the molecular refraction equals 47.36. 
Its specific rotatory power in a one decimeter tube is fal D = -f- 
9 37'. 

a-Dioxydihydrocampholenic acid, 9 C 9 H 1? O 2 . 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. 10 It melts at 144, and has \a\ D 
= + 58.03. 



i Wallach, Ann. Chem., 269, 330. 

"Tiemann, Ber., 29, 3006. 

3 Goldschmidt and Koreff, Ber., 18, 1632. 

^Goldschmidt, Ber., 18, 3297; Goldschmidt and Schulhoff, Ber., 19, 708. 

5 F. Tiemann, Ber., 29, 3006; 30, 242, 321 and 404. 

oNageli, Ber., 11, 805; Tiemann, Ber., 29, 3006. 

7 Goldschmidt and Ziirrer, Ber., 17, 2069 and 2717. 

8 Kachler and Spitzer, Ber., 17, 2400; Monatsch. fiir Chem., 3, 216; 4, 643. 

9 Tiemann, Ber., 29, 3006; Wallach, Ann. Chem., 269, 327 and 343. 

"Compare with Bouveault, Bull. Soc. Chim., 19, 1898 (III.), 565. 



CAMPHOK. 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., SO, 104. Ber., SO, 483. 



/ 3 / 2 

C 8 H U \| ........... Camphor ............ G 6 H U \\ 

yCHj Y /CH, 

C 8 H M <f I ........ Camphoroxime ......... CgH,^ I 

\CNOH \CNOH 



C 8 H 



/CH 2 /CH 

14 < I ............ Bornylamine .......... C 8 H U < I 

XJH.NH 2 



CH T 

< TT / \ \N ..... Camphoroxime ......... C 8 H 18 \ 

anhydride. 



CH.NH 2 

...... Camphylamine ....... C 81S 

\CH 2 .NH 2 



y CH.NH 2 

u < I Isocamphoroxime. C 8 H 13 \ 

XJO X CONH 2 

.CHOH } ^CH 2 

C 8 H M <f I ...... Campholenic acid ....... C 8 H 13 <f 

x;o M \COOH 

......... Campholene ............... C 8 H u =CHj 



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 9 H 16 , campholene (b. p. 130 to 140), is ob- 
tained by the dry distillation of the calcium salt of campholenic 
acid; further, an amidine 1 (m. p. 114 to 115), is formed by 

'Goldschmidt 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 1 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,< 



,H 7 
CHj 



CH S 
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, 2 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 -dioxydihydrocampholenic acid, C 10 H 18 O 4 ; it separates 
from hot water in splendid crystals, melts at 144 to 145, and 
yields a silver salt, C 10 H 17 O 4 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 9 H 18 . 

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. 3 In 
consideration of these facts, and by employing the formula of 
camphor proposed by himself, Bredt 4 explains the constitution of 

'Bamberger, Ber., 21, 1125. 

2Wallach, Ann. Chem., 269, 327 and 343. 

3 Thiel, Ber., 26, 922; compare also under pinene. 

Bredt, Ber., 26, 3054. 



DIHYDBOCAMPHOLENIMIDE. 139 

campholenonitrile and of campholenic acid by the following for- 
mulas, which he regards as the most probable : 






CH 3 CH 3 NH 

Camphoroxime. ,^<^ Intermediary product. 

CH 2 - 




C CH 3 

V CH==C CH S 

J s Campholenic acid. 

Campholenonitrile. 

According to researches of Belial, 1 and of Tiemann, 2 a second 
group of isomeric compounds is derived from camphoroxime ; 
Tiemann designates these as beta-compounds. 

/2-Campholenonitrile, 2 C 9 H 15 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 fi-camphylamine, C 10 H 17 NH 2 . 

/9-Campholenamide, 2 C 9 H 15 CONH 2 , is prepared by the saponifi- 
cation of the /9-nitrile. It melts at 86, and is optically inactive. 

/?-Campholenic acid, 2 C 9 H 115 COOH, is formed by the hydrolysis 
of /9-campholenamide. It melts at 52, and boils at 245. 

/3-Dioxydihydrocampb.olenic acid, 3 C 9 H 17 O 2 COOH, is formed by 
the oxidation of /3-campholenic acid with potassium permanganate. 
It crystallizes from chloroform or water in needles, and melts at 
146. 

Isocamphorone, 3 C 9 H 14 O, boiling at 217, and campholonic 
add, 3 C 10 H 16 O 3 , a liquid ketonic acid, isomeric with the pinonic 
acids, are also products of the oxidation of /9-campholenic acid. 

Isoamidocamplior, 4 C 10 H 15 O NH 2 , 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, 4 C 10 H 16 O NH, is obtained by distill- 
ing isoamidocamphor under atmospheric pressure in such a 



l, 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; 131 (1900), 803. 

sTiemann, Ber., 30, 242. 

<Tiemann, 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, 1 C 10 H 16 O 2 , 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 /3-modification, which, in turn, is hydrolyzed to /9-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, 
n^= 1.46801, and the molecular refraction, M= 45.79. It is 
optically inactive. 

Campholene, 2 C 9 H 16 , is formed by boiling a- and /9-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, n^ = 1.44406, at 20, and molecular refraction, M = 41.00. 

As a result of his investigations 3 on camphor and the campho- 
lene group, as well as from the researches of Tiemann and Mahla 4 
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 10 H 16 = N NH CO NH 2 , melts at 
236 to 238 (Tiemann 6 ). 

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 

'Tiemann, Ber., SO, 321 and 404; Bouveault, Bull. Soc. Chim.. 19, 1898 
(III.), 565. 

sTiemann, Ber., 30, 594. 

sTiemann, Ber., 28, 1079, 2166; 29, 119, 3006; 80, 242, 321, 404, 594; 83, 
2935; compare Bredt, Ann. Chem., 289, 15; Forster, Journ. Chem. Soc., 75, 
1141; 73, 108; Walker, Journ. Chem. Soc., 63, 495; 67, 347; 77, 394; Blanc, 
Bull. Soc. 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. 

6 Tiemann, Ber:, 28, 2191; see also Rimini, Gazz. Chim., SO (I.), 600. 



BOENEOL. 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. 1 

Campholic acid, C 9 H 17 COOH, is the parent-substance of cam- 
pholamine and camphol alcohol ; it is prepared by the method 
given by Errera. 2 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 9 H 17 CONH 2 , 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 9 H 17 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 3 ). 

For condensation-products of camphor with aldehydes, see in- 
vestigations of Haller. 4 

Camphor pinacone, C 20 H 34 O 2 , 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 5 ). 

2. BORNEOL, C 10 H 17 OH. 

Borneol occurs in nature in an optically dextrorotatory and 
levorotatory, as well as in an inactive, modification ; it is found 

'Bishop, Claisen and Sinclair, Ann. Chem., 281, 314. 

2 Errera, Gazz. Chim., 22 [1], 205; Ber., 25, 466, Ref. 

sErrera, Gazz. Chim., 22 [2], 109; Ber., 26, 21, Ref. 

A. Haller, Compt. rend., 128, 1270; 130, 688; 133, 79; see also Hel- 
bronner, Compt. rend., 133, 43. 

5 E. Beckmann, Ber., 22, 92; 27, 2348; Ann. Chem., 292, 1; Journ. pr. 
Chem. [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 
JSlumea 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 x 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 2 has 
found it in the oil of Abies siberiea L. In the same manner bor- 
neol occurs in oil from Satureja ihymbra L., oil of golden rod, 
sage oil, and oil of thyme. According to Kremers, 3 the oil of 
Picea nigra is especially rich in levo-bornyl acetate. 

Borneol (" levo-camphenol " 4 ) 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 5 modification of the old 
method proposed by Jackson and Menke, 6 and Immendorf. 7 

Fifty grams of camphor are dissolved in 500 cc. 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 
cc. 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, 8 the borneol so prepared 
is not pure, but contains about twenty per cent, of isoborneol. 

Bertram and Walbaum, Arch. Pharm., 231, 290. 
*Hirschsohn, Pharm. Zeitsch. f. Russland, 1892, No. 38. 
3 Kremers, Pharm. Rundschau, 18, 135. 

*Bouchardat and Lafont, Compt. rend., 113, 551; 125, 111. 
6 Wallach, Ann. Chem., 230, 225. 
6 Jackson and Menke, Ber., 15, 16 and 2730. 
7 Immendorf, Ber., 17, 1036. 

sBertram and Walbaum, Journ. pr. Chem., N. F., 49, 12; see Beckmann, 
Journ. pr. Chem., 55, 1897 (II.), 31. 



METHYL, BOBNYL ETHER. 



143 



These chemists obtained chemically pure borneol by saponification 
of crystalline bornyl 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 2 ). 

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 3 ). 

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 ; 4 the properties of these compounds are 
given in the following table : 





Boiling Point, 
(10 mm.). 


Optical 
Rotation in 100 


Sp. Gr. at 
15. 


Refraction i\ D 
at 15. 


Percentage 
of Ester 
Determined by 












Titration. 


Formate. 


90 


+31 


1.013 


1.47078 


97.89 


Acetate. 


80 


38 20' 


0.991 


1.46635 


100.60 


Propionate. 


109 to 110 


+ 24 


0.979 


1.46435 


97.07 


Butyrate. 


120 to 121 


+22 


0.966 


1.46380 


99.20 


Valerate. 


128 to 130 


+ 20 


0.956 


1.46280 


98.56 



Bornyl acetate, C 10 H 17 O-COCH 3 , is of especial importance, since 
it is a constituent of the oil of pine needles, and because it is a solid 
and possesses great power of crystallization. It melts at 29 and 
forms orthorhombic, hemihedral crystals (Traube). 

Methyl bornyl ether, C ]0 H 17 OGH 3 , was prepared by Baubigny 5 
and by Briihl. 6 It is a liquid, boiling at 194 to 195. 

iBeckmann, German patent, No. 42458; Ber., 21, 321, Ref.; 22, 912. 
*Traube, Journ. pr. Chem., N. F., 49, 3. 
sWallach, Ann. Chem., 230, 226. 

4 Bertram and Walbaum, Arch. Pharm., 231, 303; see also Minguin, 
Compt. rend., 123, 1296. 

sBaubigny, Ann. Chim. Pliys. [4], 19 (1870), 221. 
"Briihl, Ber., 24, 3377 and 3713. 



144 THE TERPENES. 

Ethyl bornyl ether, C 10 H 17 OC 2 H 5 , 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 l 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 and a rotatory power, 
[*]= + 26.3. 

Methylene bornyl ether, (C 10 H 17 O) 2 CH 2 , 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 
(Briihl 2 ). Briihl 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 3 and Min- 
guin 4 ). 

Bornyl phenylurethane, C 6 H 5 NH CO OC 10 H 17 , was first pre- 
pared by Leuckart 5 by the action of phenyl isocyanate on borneol. 
It melts at 138 to 139 (Bertram and Walbaum 6 ). 

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 IO H 17 O CS SH, was obtained by Bam- 
berger and Lodter 7 by the action of carbon bisulphide on sodium 
bornylate, and analyzed in the form of its cuprous salt. 

Bornyl chloride, C 10 H 17 C1, was described by Kachler 8 as borneol 
chloride. It is most conveniently prepared by the following 
method. 9 

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. 

"Briihl, Ber., 24, 3377 and 3713. 

Haller, Compt. rend., 112, 143. 

4 Minguin, Compt. rend., 116, 889. 

Leuckart, Ber., 20, 115. 

6 Bertram and Walbaum, Arch. Pharm., 231, 303. 

7 Bamberger and Lodter, Ber., 23, 214. 

"Kachler, Ann. Chem., 197, 93. 

9 Wallach, Ann. Chem., 230, 231. 



BOENYL IODIDE. 145 

at a time. 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, 1 and Jiinger and Klages, 2 bornyl 
chloride is stereoisomeric with isobornyl chloride and camphene 
hydrochloride, the two latter being identical. 

According to Wagner, 3 most of the bornyl chloride, prepared as 
above described, is readily converted into camphene by boiling 
with alcoholic potash, and therefore consists chiefly of isobornyl 
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 bornyl 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 4 also seem to indicate that 
pinene hydrochloride is the true chloride corresponding with 
borneol. 

Bornyl Iodide, C 10 H 17 I. According to Wagner, 3 a mixture of 
bornyl 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 

>A. Reychler, Ber., 29, 697; Bull. Soc. Chim., 15, 1896 (III.), 366. 

2 Jtinger and Klages, Ber., 29, 544. 

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

F. Semmler, Ber., 88, 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 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 2 (O - C 10 H 17 ) 2 , 
is a compound prepared by Brochet 1 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, 2 borneol is to be 
regarded as a secondary alcohol, and is not stereoisomeric with 
isoborneol. 

3. ISOBORNEOL, C 10 H 17 OH. 

It has been mentioned that camphene, C 10 H 16 , 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. 3 While studying the effect of this method on cam- 
phene, Bertram and Walbaum 4 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 5 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 6 isolated the latter compound in a 
pure condition, and called it " isocamphol." This substance is 
identical with Bertram and Walbaum's isoborneol. 

1 A. Brochet, Compt. rend., 128, 612. 
*F. Semmler, Ber., S3, 774. 
3 Bertram, German patent, No. 67255. 
'Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 1. 
5 Montgolfier, Compt. rend., 83, 341. 
r, Compt. rend., 109, 187. 



PREPARATION OF ISOBORNEOL. 147 

Preparation of Isoborneol. 1 

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 isobornyl 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 
with a 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 2 
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 zinc 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 3 has further shown that when isoborneol is heated 

'Bertram and Walbaum, Journ. pr. Chem., N. F., %9, 1. 
2 According to Semmler (Ber., 33, 3420), isoborneol gives a small yield of 
camphor on oxidation with dichromate and sulphuric acid. 
3F. Semmler, Ber., 33, 774. 



148 THE TERPENES. 

with zinc dust for half an hour at 220, it is converted into a 
small quantity of camphene, together with a larger amount of 
isodihydrocamphene, C 10 H 18 (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 10 H 17 OCH 3 , 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 10 H 17 OC 2 H 5 , is formed in an analogous 
manner ; it boils at 203 to 204, and has the sp. gr. 0.907 at 
15. According to Semmler, 1 this compound is also prepared by 
boiling a mixture of camphene, alcohol, and sulphuric acid. 

Methylene isobornyl ether, (C 10 H 17 O) 2 CH 2 , 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 

Semmler, Ber., S3, 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 6 H 5 NH CO OC 10 H 17 , is difficultly 
soluble in petroleum ether, more readily in warm alcohol and 
benzene. 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: 





Jsoborneol. 


Borneol. 


Crystal form, 


hexagonal, double refrac- 
tion -f- , 


hexagonal, double refrac- 
tion . 


Melting point, 


212, 


203 to 204. 


Boiling point, 


undetermined, 


212. 


Solubility in benzene at 
0, 


1 : 2.5 to 3, 


1:6.5 to 7. 


Solubility in benzene at 
20, 


1 : 1.5 to 2, 


1 : 4 to 4.5. 


Solubility in petroleum 
ether at 0, 


1 : 4 to 4.5, 


1 : 10 to 11. 


Solubility in petroleum 
ether at 20, 


1 : 2.5, 


1:6. 


Phenylurethane, 


m. p. 138 1 
to 139, 


isoborneol is 
regenerated 
by treat- 
ment with 
alcoholic 
potash, 


m. p. 138 "I 
to 139, 


borneol is 
regenerated 
by treat- 
ment with 
alcoholic 
potash. 


Chloral compound, 


liquid, 


m. p. 55 
to 56, 


Bromal compound, 


m. p. 72, 


m. p. 98 
to 99, . 


Formyl ester, 


liquid, b. p. 
(14 mm. ), 


100 


liquid, b. p. 
(15 mm. ). 


98 to 99 


Acetyl ester, 


liquid, b. p 
(13mm.), 


107 


m. p. 29 ; b. p. 106 to 
107 (15mm.). 


Behavior towards zinc 
chloride or dilute sul- 
phuric acid, 


forms camphene, 


unchanged. 


Behavior towards sul- 
phuric acid and methyl 
or ethyl alcohol. 


forms methyl or ethyl 
isobornyl ether, 


does not yield ethers by 
this treatment. 



150 THE TERPENES. 

Isobornyl chloride, 1 C 10 H 17 C1, 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, 2 camphor has the specific rotatory 
power, \a\ D == 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 : 

Dissolved in 5 parts of alcohol, [a\ D = 42.4 and + 42.51, 
" " 12 " [XU= 41.38 and + 42.38. 

Camphoroxime hydrochloride (m. p. 162) has the specific ro- 
tatory power, \a\ D = 43.98 and -f 42.52. 

Borneol has a different rotatory power according to its origin ; 
thus Beckmann 3 found the rotatory power of d-borneol to be 
[a] D = + 37.44, and Haller 4 determined the rotatory power of 
borneol regenerated from the crystalline acetate, [a] D = + 37.63. 
Natural 1-borneol has [a\ D = 37.74 (Beckmann 3 ), and 37.77 
fHaller 5 ) ; a 1-borneol occurring under the name of Ngai fen has 
\a\ D = - 39 25' (Schimmel & Co. 6 ). 

According to Bertram and Walbaum, 7 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] D = + 4.71. 
Dissolved in benzene, []^= -f 2.88. 

'A. Reychler, Ber., 29, 697; Bull. Soc. Chim., 15, 1896 (III.), 366; see 
also Jiinger and Klages, Ber., 29, 544. 
2 Beckmann, Ann. Chem., 250, 352. 

"Beckmann, Ann. Chem., 250, 353; Journ. pr. Chem. [II.], 55, 31. 
* Haller, Compt. rend., 109, 30; 112, 143. 
Haller, Compt. rend., 108, 456; 109, 456. 
5 Schimmel & Co., Semi-Annual Report, April, 1895, 76. 
'Bertram and Walbaum, Journ. pr. Chem., ^9, 14. 



ALDEHYDE FROM CAMPHENE GLYCOL. 151 

4. CAMPHENE GLYCOL, C 10 H 16 (OH) 2 . 

Camphene glycol is closely allied to borneol ; it was obtained 
by G. Wagner l 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 10 H 16 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 10 H 16 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 1 ). 
(See camphenilanic acid, page 65.) 

iQ. Wagner, Ber., 25, 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, 1 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 10 H 16 (OH) 2 , is described by Wagner ; it is men- 
tioned under pinene (see page 46). 

5. CAMPHOL ALCOHOL, C 10 H 19 OH. 

According to Errera, 2 if a solution of campholamine hydro- 
chloride be warmed with silver nitrite, camphol alcohol, C 10 H, 9 OH, 
is produced, together with a hydrocarbon, C 10 H lg . This alcohol 
is a liquid having an agreeable odor, and boils at 203. 

Since campholamine contains the group, CH 2 NH 2 , it would 
be expected to yield a primary alcohol ; Errera, 3 however, de- 
termined by the speed of the ester formation that camphol alcohol 
is a tertiary alcohol. 

6. CAMPHENONE, C 10 H U O. 

Claisen and Manasse 4 prepared amidocamphor by reduction of 
isonitroso-camphor, 



/C=NOH 

u \ I 

x c=o 



with zinc dust and acetic acid ; by treating amidocamphor with 
nitrous acid, Angeli 5 obtained diazo-camphor, 



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, catnphenone, C 10 H U 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 6 ). 

iBredt and Jagelki, Ann. Chem., 310, 112. 
zErrera, Gazz. Chim., 22 [2], 114; Ber., 26, 21, Ref. 
sErrera, Gazz. Chim., 23 [2], 497; Ber., 27, 126, Ref. 
*Claisen and Manasse, Ann. Chem., 274, 88. 
s Angeli, Ber., 26, 1718; Rimini, Gazz. Chim., 26 [2], 290. 
s Angeli, Gazz. Chim., 24 [2], 44 and 317; Ber., 27, 590, 797 and 892, 
Ref. 



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, 1 C 10 H 14 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, 1 C 10 H 14 O Br 2 , 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 10 H 13 BrO, is obtained by treating 
camphenone dibromide with alcoholic potash ; it forms large, well 
defined crystals, melting at 70. 

Camphenonoxime, 2 C 10 H 14 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, 2 C 10 H ]4 N 2 O 2 , 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 10 H 14 N 2 O 2 Br 2 , is produced by the addition of bromine to a chlo- 
roform solution of pernitrosocamphenone. It crystallizes from 
petroleum and melts at 133. 

Isocamphenone, C 10 H 14 O. When pernitrosocamphor, C 10 H 16 N 2 O 2 
(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 10 H 15 - 
BrN 2 O 2 (m. p. 114), is formed; this is converted into isobromo- 
pernitrosocamphor, C 10 H l; .BrN 2 O 2 (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 oxirne melts at 170. 

'Angeli and Rimini, Atti. d. R. Ace. d. Lincei Rudct., 1895 [1], 390; 
Gazz. Chim., 26 [2], 34 and 45. 

2 Angeli, 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 10 H 16 O. 

This ketone, which is isomeric with camphor, is formed as a 
by-product in the preparation of pinylamine, C 10 H 15 NH 2 , from 
nitrosopinene, C ]0 H 17 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. 2 

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, np = 1.47273, at 21; its molecular refraction 
is 44.44, while that calculated for the compound, C 10 H 16 O, is 
44.11. 

Pinocamphonoxime, C 10 H 16 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, 3 C 10 H 17 NH 2 , which is a liquid ; it rapidly 
absorbs carbon dioxide, forms a carbamide (m. p. 204), and an 
acetyl derivative (m. p. 120). 

Pinocampholenonitrile, C 10 H 15 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 nit-rile, while much of the oxime remains unaltered. The 
nitrile is obtained by distilling the reaction-product with steam. 

iWallach, Ann. Chem., 268, 210. 
'Wallach, Ann. Chem., 300, 287. 
aWallach, Ann. Chem., SIS, 345. 



FENCHONE. 155 

The nitrile l 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 pinocampholenic acid, C 10 H 16 O 2 , 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 10 H 16 O, as the 
dihydro-derivative of an unknown ketone, C 10 H U O, which cor- 
responds with nitrosopinene, C 10 H U NOH. 

A ketone, C 10 H 16 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. PINOOAMPHEOL, C 10 H 17 OH. 

This alcohol, isomeric with borneol, IB 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 zinc chloride, it loses water and yields products among 
which cymene has been identified. 

Pinocamphyl phenylurethane, 



\OC 10 H 1T 
forms a crystalline mass, and melts at 98. 

9. FENCHONE, C 10 H 16 O. 

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, 2 
while levo-fenchone forms a constituent of thuja oil. 3 

Wallach, Ann. Chem., 313, 345. 

"Wallach and Hartmann, Ann. Chem., 259, 324. 

sWallach, Ann. Chem., 212, 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. 1 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 2 ). 

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 j the resulting oil is washed 
with sodium hydroxide, again distilled with steam, and the pure 
levo-fenchone is crystallized by the method suggested above. 

JWallach, Ann. Chem., 263, 130. 
"Wallach, Ann. Chem., 272, 102. 



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 isothujoue, 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. 2 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. 3 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, 4 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 
n^ = 1.46306 at 19, corresponding to a molecular refraction of 

'Wallach, Ann. Chem., 286, 103. 
zWallach, Ann. Chem., 263, 146. 
a Wallach, Ann. Chem., 263, 131 ; 272, 103. 
'Wallach, Ann. Chem., 272, 107. 



158 THE TERPENES. 

44.23 while the calculated value for a compound of the compo- 
sition, C 10 H 16 O, containing no ethyleiie 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 10 H 12 O [CH 3 : CH 3 : 
CH 3 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-xylic acid, 
C 9 H 10 O 2 , 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, 2 when fenchone is heated 
with concentrated nitric acid on the water-bath for six days, 
it is oxidized to isocamphoronic acid, C 9 H 14 O 6 (m. p. 163 to 
164), dimethyltricarballylic acid, C 8 H 12 O 6 (m. p. 152), dimeth- 
ylmalonic acid, C 5 H g O 4 (m. p. 190), isobutyric acid, and acetic 
acid; in addition to these acids a nitrofenchone, C 10 H 15 O-NO 2 , 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 ; 
hydrocyanic acid is one of the products of this reaction. 

Potassium permanganate oxidizes fenchone to a mixture of 
acetic, oxalic and dimethylmalonic acids (Wallach 3 ). 

When phosphorus pentachloride is allowed to act upon fen- 
chone for six weeks in the cold, and the product is subsequently 
treated with water, ehlorofenchene-phosphoric acid, C 10 H ]4 C1PO- 
(OH), melting at 196, a- and ft-chlorofencliene hydrochlorirfes, 

] J. E. Marsh, Journ. Chem. Soc., 75, 1058; compare with Glaus, Journ. pr. 
Chem., Jfl (II.), 396; Armstrong and Kipping, Journ. Chem. Soc., 63, 75. 
2 Gardner and Cockburn, Journ. Chem. Soc., 73, 708. 
sWallach, Ann. Chem., 263, 134. 



TRIBROMOFENCHONE. 159 

C 10 H 16 C1 2 , and chlorofenchene, C 10 H 15 C1, a solid, boiling at 80 to 
83 under 16 mm. pressure, are produced. 1 

Bromofenchone, 2 C 10 H 15 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 a rotation -f 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 zinc dust and acetic acid. 

When bromofenchone is heated with an excess of alcoholic 
potash, a-fencholenic acid, C 10 H 16 O 2 , is produced, identical with that 
obtained by Wallach ; when cooled with liquid air, it crystallizes. 
An isomeric compound, 3 C 10 H 16 O 2 , 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 (I.), 244.) 

Tribromofenchone, 3 C 10 H 15 OBr Br 2 , 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 10 H 15 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, 4 C 10 H 20 , results when fenchone is heated 
with phosphorus and hydriodic acid ; the same hydrocarbon is ob- 
tained from fenchyl 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 10 H 17 NH 2 , a base isomeric with bornylamine, is 
formed. 

It differs from camphor in that it does not form an oxymeth- 
ylene compound. 5 

'Gardner and Cockburn, Journ. Chem. Soc., 71, 1156; 73, 704. 
2 Czerny, Ber., 33, 2287; see Balbiano, Gazzetta, 30 [II.], 382. 
3 Czerny, Ber., 33, 2287. 

'Wallach, Gottinger Nachrichten, 1891, 309; Ann. Chem., 284, 326. 
sWallach, Ber., 28, 34. 



160 THE TERPENES. 

The behavior of fenchone towards phosphorus peutoxide is of 
especial interest in showing the resemblance of the reactions of 
fenchone and of camphor. According to Wallach, 1 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-Gymene, 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 2 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, 3 C 10 H 16 -N-NH-CO-NH 2 , cannot be 
prepared directly from fenchone and a semicarbazide solution. 
It is formed, however, by gently heating pernitrosofenchone, 
C 10 H 16 N 2 O 2 , with semicarbazide acetate on the water-bath. It 
separates from alcohol in white crystals, and melts at 186 
to 187. 

Fenchonoxime, C 10 H 16 NOH, is conveniently prepared in small 
quantities by the following method (Wallach 4 ). To five grams of 
fenchone dissolved in eighty cc. 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. 

'Wallach, Ann. Chem., 275, 157. 

* Bouchardat and Lafont, Compt. rend., 126, 755. 

sRimini, Gazz. Chim., 30 (I.), 600. 

Wallach, Ann. Chem., 284, 324; 272, 104. 



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. 2 

Fenchonoxime crystallizes from alcohol in fine needles, and from 
ethyl acetate or ether in well formed, monoclinic 3 crystals, which 
melt at 161 when heated rapidly. 4 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, 5 [a] D = 
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 10 H 17 NH 2 , analogous to bornylamine, is pre- 
pared by reducing fenchonoxime with sodium and alcohol. 

Fenchonoxime anhydride, 6 C 10 H 15 N (a- and /3-fencholenonitrile, 
C 9 H 15 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. 

iWallach, Ann. Chem., 263, 136. 

2 For preparation of fenchonoxime, see also Rimini, Gazz. Chim., 26 ( II. ) , 
502. 

"Zander, Ann. Chem., 259, 327. 

*Mahla 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. 

6\Vallach and Binz, Ann. Chem., 276, 317; 272, 104. 

6 Wallach 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]^ = + 43.31. It boils at 217 to 218 , 1 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 hydrobroinic and hy- 
driodic acids, forming the solid, but unstable, addition-products, 
C 10 H 15 N HBr and C 10 H 15 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 10 H 15 N HC1, 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 2 ). 

Fenchonoxime anhydride is to be regarded as a nitrile, 
C 9 H, 5 CN, since it may be converted into a- and /?-fencholenic acids, 
C 9 H 15 COOH, and a-fencholenamide ; the latter is identical with 
a-isofenchonoxime. 

When it is reduced with sodium and alcohol, an unsaturated 
base, fencholenamine, 3 C 10 H 17 NH 2 , is formed ; this amine is isomeric 
with camphylamine. 

a-Isofenchonoxime, C 10 H 17 NO (a-fencholenamide, C 9 H 15 CONH 2 ). 
The transformation of fenchonoxime anhydride into the corre- 
sponding acid amide, and more especially into the acid itself, is 
eifected much more slowly than the like transformation of camphor- 
oxime anhydride into -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 cc. 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 recrystal- 
lizing from alcohol. It melts at 113 to 114, and dissolves in 

1 According to Cockburn (Journ. Chem. Soc., 75, 503), it boils at 214 to 
219. 

Wallach, Ann. Chem., 269, 330. 

s Wallach and Jenkel, Ann. Chem., 260, 369. 



tt-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 -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 isofencholenyl alcohol (see page 176). 

/3-Isofencb.onoxime, 2 C 10 H 17 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, /3-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 /?-isoxime 
with permanganate, dimethylmalonic acid is formed ; therefore, 
it has in all probability the same atomic structure as fenchone. 

/3-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 /9-isoxime with hydrogen chloride ; it soon loses 
hydrochloric acid by standing in the air. 

The sulphate, obtained by treating the ethereal solution of the 
/9-isoxime with concentrated sulphuric acid, forms brilliant needles. 

a-Fencholenic acid, 3 C 9 H ]5 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 
crystallizes. 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 

1 Wallach, Ann. Chem., 269, 332; 259, 330; 315, 273. 
2 Wallach, Ann. Chem., 269, 332; 284, 333. 
"Wallach, 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 1 is formed, which melts at 76. 

Silver a-fencholenate, C 10 H 15 O 2 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. 

Hydrocblorofencliolenic acid, C 10 H ir ClO 2 , 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, 2 C 10 H 17 BrO 2 , 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. 3 

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 dihydrofeneholene, C 9 H 18 . 

Dihydrofencholene boils at 140 to 141; its specific gravity 
is 0.790 and refractive power, n^, = 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, 4 a second series 

iWallach, Ann. Chem., S15, 273. 
2 Cockburn, Journ. Chem. Soc., 75, 506. 
sBinz, Ann. Chem., 269, 338. 

4 Cockburn, Journ. Chem. Soc., 75, 501. Wallach has also confirmed these 
observations, see Ann. Chem., 315, 273. 



/9-FENCHOLENIC ACID. 



165 



of isomeric substances is derived from fenchonoxime ; Cockburn 
designates these as beta-compounds. 

/2-Fencholenonitrile, C 9 H 15 -CN. According to Cockburn, the 
fencholenonitrile, prepared as described tinder fenchonoxime 
anhydride by the action of dilute sulphuric acid on fenchonoxime, 
is a mixture of the a- and /9-nitriles, and boils at 214 to 219 ; 
on saponification it yields a- and /9-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] 1) == -|- 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 /9-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]^> = + 43.66. It is quantitatively and very 
readily converted into /9-fencholenic acid on hydrolysis, but ap- 
parently cannot be changed into the /9-amide by the action of 
alcoholic potash. 

/9-Fencholenamide, C 9 H 15 -CONH 2 . 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 /?-amide is produced, however, by heating the ammonium 
salt of /?-fencholenic acid in a 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. 

/9-Fencholenic acid, 1 C 9 H 15 -COOH, is prepared by the hydrolysis 
of the mixture of a- and /3-nitriles by heating with alcoholic pot- 
ash for two and one-half days ; all of the /?-nitrile is thus con- 
verted into the /9-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 /?-acid is about 55 to 60 per cent., and of a-amide 35 per cent, 
of the theoretical, the remainder being the a-acid. 

/9-Fencholenic acid is purified by recrystallization from light 
petroleum ; it meltj at 72 to 73, boils without decomposition at 
259 to 260, and has the specific rotatory power, []/>= 4- 
19.64. It is readily soluble in alcohol, ether, and acetone, less 
so in benzene and glacial acetic acid. It is an unsaturated acid, 

'Cockburn, Journ. Chem. Soc., 75, 503; see Wallach, Chem. Centr., 1899 
(II.), 1052; Nachr. k. Ges. Wiss. Gottingen, 1899, No. 2. 



166 THE TEKPENES. 

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. 

/3-Fencholenic acid yields a brominated lactone, 1 melting at 80, 
by the action of sodium hypobromite on the cold solution of the 
sodium salt. 

According to Cockburn, pure a-fencholenic 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, [a] D = + 30.73. 

Hydrobromo-/9-fencliolenic acid, C 10 H 17 BrO 2 , is formed during 
the action of bromine on a solution of the /9-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. 2 

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 fonchonimine ni- 
trate, C 10 H 17 N-HNO 3 , melting at 152, while the other remains in 
the ethereal liquid after separation of the nitrate, and is called 
fenchonitrimine, C 10 H 16 N 2 O 2 , melting at 58. 

According to Angeli and Rimini, when a dilute hydrochloric 
acid solution of fenchonoxime is treated with sodium nitrite, per- 
nitrosofenchone, C 10 H 16 N 2 O 2 , 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 isopernitrosofenchone, C 10 - 
H lg N 2 O 2 ; this compound melts at 88. Pernitrosofenchone and 
its isomeride are both converted into isocamphor, C 10 H 16 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, 3 C, H 16 NH, results by the action of twenty-five 
per cent, aqueous ammonia on fenchonitrimine, C 10 H 16 N 2 O 2 . It 

^Wallach, Ann. Chem., 315, 273. 

zMahla and Tiemann, Ber., 29, 2807 ; Angeli and Riinini, Gazz. Chim., 26 
[II.], 228; Rimini, Gazz. Chim., 26 [II.], 502; 30 [I.], 600. 
3F. Mahla, Ber., 34, 3777. 



OXYDIHYDEOFENCHOLENAMIDE. 167 

boils at 83 (15 mm.), has the specific rotatory power, [a\ D = -f 
76.3, at 19.5 (10 cm. tube), sp. gr. is 0.9322 at 11.5, re- 
fractive index is 11^= 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 9 H 17 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'l6.5, n^ = 1.44743 at 17.5, M= 45.15, 
and [a] D = + 25 at 19 (10 cm. 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 9 H 17 CONH 2 , 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 9 H 17 -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] D = + 4.3 
at 15.5 (10 cm. tube). It forms silver and ammonium salts, of 
which the latter may be reconverted into the amide. 

Oxydihydrofencholenonitrile, C 9 H 17 O-CN, is produced in a yield 
of about thirty-five per cent, by the action of air on feuchimine. 
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, n^, = 1.46464.at 
18, M = 47.11, and [a\ D = 8 at 18 (10 cm. tube). 

Oxydihydrofencliolenamide, C 9 H 17 O-CONH 2 , 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 ]0 H 17 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 
/9-isofenchonoxime (m. p. 137), which is prepared by dissolving 
a-feneholenamide (ra. p. 113 to 114) in hot, dilute sulphuric acid 
and precipitating the filtered solution with alkali. 

5-Oxydihydrofencholenic acid, C 9 H 17 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. 

d-Oxydihydrofencholenic acid lactone, C 10 H ]6 O 2 , 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, 1 C 10 H 16 (OH) COOH. 

When carbon dioxide is passed through a solution of fenctibne 
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 n H 16 O 2 , an- 
hydrofenchocarboxylic acid, C n H 16 O 2 , and a pinacone, C 20 H 34 O 2 , 
or a difenchone, C 20 H 32 O 2 . This mixture is treated with sodium 
hydroxide or ammonia, shaken with ether, and the aqueous 
liquor is acidified ; -fenchocarboxylic acid crystallizes from 
this liquid more rapidly than the /?-acid. The /?-acid is also 
more soluble in petroleum ether than the a-acid, and a final 
separation may be made by means of this solvent. 

1 Wallach, Ann. Chem., 284, 324; 800, 294; Chem. Centr., 1899 (II.). 
1052; Nach. k. Ges. Wiss., Gottingen, 1899, No. 2; Ann. Chem., 315, 273. 






CARBOFENCHONONE. 169 

a-Fenchocarboxylic acid, C n H 18 O s , 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]^ = -f- 11.28, in a 4.5 per cent, ethereal solu- 
tion ; by mixing equal weights of the active acids prepared from 
d- and 1-fenchone, an inactive acid is obtained, which melts at 91 
to 92. It forms lead and silver salts. 

/?-Fenchocarboxylic acid, C n H 18 O 3 , 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 lead 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 U H 16 O 2 , 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, 1 C U H 16 O 2 , 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 
/9-fenchocarboxylic acid. It yields a monoxime, C n H ]6 O NOH, 
which crystallizes from methyl alcohol in needles, melting at 108; 
and a dioxime, C n H 16 (NOH) 2 , which is soluble in water, and melts 
at 198 to 199. By the action of ammonia it forms a compound, 
C n II ]7 NO, which crystallizes from alcohol and melts at 205. 

Carbofenchonone is an ortho-diketone. 1 By the action of zinc 
dust and acetic acid it is converted into an alcohol, C U H 18 O 2 , which 
crystallizes from dilute alcohol and melts at 89. When the 
diketone is oxidized, it yields a dicarboxylic add, C U H 18 O 4 , which 
melts at 172 to 173. 

A lactone, C 10 H 10 O 2 , 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, 1 C 20 H 34 O 2 , or a difenchone, C 20 H 32 O 2 , 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 2 OH CH CH 3 

I H 3 C C CH 3 

CH, CH CO 

Fenchone. 

10. FENCHYL ALCOHOL, C 10 H 17 OH. 

Fenchyl alcohol is formed by the reduction of fenchone in an 
alcoholic solution with sodium (Wallach 2 ). 

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, 3 the benzoyl esters of fen- 
chyl alcohol and isoborneol are formed by heating the dextroro- 
tatory terpene (pinene 4 ), obtained from eucalyptus oil of Eucalyptus 

'Wallach, Ann. Chem., 315, 273. 

2 Wallach, Ann. Chem., 263, 143; see also Gardner and Cockburn, Journ. 
Chem. Soc., 73, 276. 

"Bouchardat and Tardy, Compt. rend., 120, 1417. 

^Compare with Wallach and Gildemeister, Ann. Chem., 2^6, 283. 



FENCHYL FORMATE. 171 

globulus, with benzole acid. By the action of certain acids (sul- 
phuric, benzoic) on French (levorotatory) turpentine, Bouchardat 
and Lafont * obtained a mixture of dextrorotatory and inactive 
fenchyl 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 2 
or obtained by the hydrolysis of fenchyl hydrogen phthalate, 3 
melts at 45. 

Fenchyl alcohol prepared from dextrorotatory fenchone is 
levorotatory; 4 its specific rotatory power is [a] z> = 10.35 
(Wallach), and [a] D = -13.37 (Gardner and Cockburn 5 ). By 
reduction, levo-feuchone yields dextro-fenchyl alcohol, 6 whose 
specific rotatory power is []/> = + 10.36. Inactive fenchyl 
alcohol results by mixing the two active modifications, and melts 
at 33 to 35 (Wallach). 

Wallach 7 designates the levo-fenchyl alcohol obtained from 
dextro-fenchone as D-1-fenchyl alcohol, and the dextro-alcohol 
derived from levo-fenchone as L-d-fenchyl 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 10 H 16 , is formed by warming fenchyl alcohol with 
acid potassium sulphate, while tetrahydrofenchene, C 10 H 20 , is pro- 
duced by reducing it with hydriodic acid and phosphorus. 

The following derivatives of feuchyl alcohol have been pre- 
pared by Bertram and Helle. 3 

Fenchyl formate, C 10 H )7 O-COH, boils at 115 under 40 mm. 
pressure, and at 84 to 85 under 13 mm. pressure; it has a 

i Bouchardat and Lafont, Compt. rend., 113, 905; 125, 111; 126, 755. 

Wallach, Ann. Chem., 284, 331. 

'Bertram and Helle, Journ. pr. Chem., 16, 1900 (II.), 293. 

*See Kondakoff and Lutschinin, Journ. pr. Chem., 62 (II.), 1. 

"Gardner and Cockburn, Journ. Chem. Soc., 73, 276. 

eWallach, Ann. Chem., 272, 106. 

'Wallach, Ann. Chem., 302, 371. 



172 THE TERPENE8. 

specific gravity 0.988 at 15, and the optical rotation, [a] D = 
73 14'. 

Fenchyl acetate, C 10 H 17 O-COCH 3 , 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 1 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, 1 C 10 H 17 O-COC 6 H 5 , 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 p he ny lure thane, 



crystallizes in needles or tablets, and melts at 82 to 82.5. 

Fenchyl hydrogen phthalate, C 18 H 22 O 4 , 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 fenchyl alcohol. 

Fenchyl chloride, C ]0 H 17 C1, may be readily prepared by the fol- 
lowing method (Wallach 2 ). 

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. 3 

1 Bouchardat and Lafont, Compt. rend., 126, 755. 

2 Wallach, Ann. Chem., 269, 148; see also Gardner and Cockburn, Journ. 
Chem. Soc., 73, 276; Kondakoff and Lutschinin, Journ. pr. Chem., 62 

(II-), I- 

sWallach, Ann. Chem., 284, 331. 



FENCHYL IODIDE. 173 

According to more recent investigations by Wallach, 1 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]^ = 13 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-1-fenchyl alcohol 
gives D-1-fenchyl chloride and D-d-fenchyl chloride ; for when 
pure D-1-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, 2 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 10 H 17 C1, 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 fenchyl chloride 2 is obtained by heating fenchyl 
alcohol on the water-bath with concentrated hydrochloric acid ; at 
higher temperatures a dichloride is formed. 

Fenchyl bromide, C 10 H 17 Br, is produced by the action of cold 
hydrobromic acid on D-1-fenchyl alcohol ; it boils at 92 to 96 
(11 mm.), has the sp. gr. 1.2368 at 19.5, n / ,= 1.4988 and [a~\ D 
= 4317'. 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, 3 C 10 H 17 I, is prepared by the action of a solution 
of hydrogen iodide saturated at 20 on fenchyl alcohol at the 
ordinary temperature ; it boils at 120 to 123 under 23 mm. 

"Wallach, Ann. Chem., 302, 371 ; 3.75, 273. 

Kondakoff and Lutschinin, Journ. pr. Chem., 1900 [II.], 62, 1. 
'Kondakoff and Lutschinin, Chem. Zeit., 25, 131. 



174 THE TERPENES. 

pressure, has a 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 10 H 17 OH. 

As a result of experiments l 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 10 H 16 , with a mixture of acetic and sulphuric acids 
in the same manner as in the preparation of isoborneol 2 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 10 H 16 O. 
When this ketone is reduced, it gives rise to a new alcohol, 
C 10 H 17 OH, which apparently is not identical with fenchyl or 
isofenchyl alcohol. 

Isofenchyl alcohol is prepared 3 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, i\ D = 1.48005, at the same temperature, 
and a specific rotation, [a\ D = 25.73, in an alcoholic solution. 
It reacts like a saturated secondary alcohol. 

When a benzene solution of isofenchyl alcohol is boiled with 
zinc chloride, it loses water and yields a hydrocarbon, C 10 H 16 , 
which is probably identical with fenchene. 

Isofenchyl acetate, C 10 H 17 O . COCH 3 , 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 

iSchimmel & Co., Semi-Annual Report for Oct., 1898, 49; April, 1900, 55 
and 60; Bertram and Helle, Journ. pr. Chem., 61, 1900 (II.), 293. 

1 Bertram and Walbaum, Journ. pr. Chem., 49 (II.), 1. 

3 According to Wallach, Ann. Chem., 815, 273, it is also formed from 
fenchene alcoholate, C 10 H 17 OC 2 H B . 



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 phenylur ethane, 

/NHC 6 H 5 
CO 
\OC 10 H 17 

crystallizes from alcohol, and melts at 106 to 107. 

Isofenchyl hydrogen phthalate, C 18 H 22 O 4 , is a colorless, crystalline 
powder, and melts at 149 to 150. It is converted into pure 
isofenchyl alcohol on hydrolysis, hence it may be employed for the 
purification of the alcohol. 

The ketone, C 10 H 16 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 IO H, 7 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 
110 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 folio wing table. 1 It will be noted 
that the compounds derived from isofenchyl alcohol have, in most 
instances, higher boiling and melting points, than the correspond- 
ing fenchyl alcohol derivatives. 





Isofenchyl alcohol. 


Fenchyl alcohol. 


Melting point, 


61.5 to 62, 


45. 


Boiling point, 


97 to 98 (13mm.), 


91 to 92 (llmm.). 


Phenylure thane, 


m. p. 106 to 107, 


m. p. 82 to 82.5. 


Acetyl ester, 


liquid, b. p. 98 to 99 

(14 mm. ), 


liquid, b. p. 88 (10 
mm. ). 


Hydrogen phthalate, 


m. p. 149 to 150, 


m. p. 145 to 145.5. 


Hydrocarbon resulting by 
dehydration of alcohol, 


Fenchene (?) b. p. 155 
to 156, 


Fenchene b. p. 154 to 
156. 


Compound formed by 
oxidation of alcohol, 


Ketone, C 10 H I6 O, liquid, 
b. p. 193 to 194, 


Fenchone, C 10 H 16 O, m. p. 
+ 6 ; b. p. 191 to 192. 


Oxime of preceding com- 
pound, 


m. p. 82, 


m. p. 164 to 165. 



1 Schimmel & Co., Semi- Annual Report, April, 1900, 56. 



176 THE TERPENES. 

12. FENCHOLENYL ALCOHOL AND ISOFENCHOLENYL 
ALCOHOL, C 10 H 17 OH. 

Fencholenyl alcohol is the alcohol corresponding to a-fencho- 
lenamine, a reduction product of a-fencholenonitrile, C 9 H 15 CN. 
The following process is well adapted for its preparation (Wallach 
and Jenkel 1 ). 

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 cc. 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, 
DP = 1.4739, at 20 ; it has an agreeable odor, very similar to 
that of terpineol. It is not converted into fenchenole, C 10 H 18 O, 
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 10 H 17 OH, is apparently not identical 
with the preceding compound (Wallach 2 ). When a-isofenchonox- 
ime (a-fencholenamide) is reduced with sodium and alcohol, - 
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 3 ). 

It is an unsaturated compound, boils at 218, and has the spe- 
cific gravity 0.927 and the index of refraction, n^> = 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. 

Wallach and Jenkel, Ann. Chem., 269, 375; Wallach, Ann. Chem., 300, 
294. 

'Wallach, Ann. Chem., 300, 294. 
'Wallach, Ann. Chem., 284, 336. 



FENCHEXOLE. 177 



13. FENCHENOLE, C 10 H lg O. 

Fenchenole it* 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 
color, 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, n^, = 
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 2 ). 

1 Wallach, Ann. Chem., 284, 336. 

2 Wallach, Ann. Chem., 275, 170 and 172. 



12 



II. COMPOUNDS WHICH MAY BE REGARDED AS 
DERIVATIVES OF THE HYDROCYMENES. 

A. SUBSTANCES CONTAINING TWO ETHYLENE LINK- 
AGES. KETONES, C 10 H ]4 0, AND ALCOHOLS, C 10 H 15 OH. 

1. CARVONE, C 10 H 14 O. 

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 
(Cariwn carvi\ and of the oil of dill (Oleum, anethi). On the other 
hand, levorotatory carvone is found in the oil of spearmint, 1 
and in kuromoji oil. 2 

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, 3 if limonene tetrabromide, C 10 H ]6 Br 4 , 
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 10 H, 4 Br- 
OCH 3 , 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 4 of carvone into limonene 
may be accomplished as follows. On reduction with alcohol and 

Fliickiger, Ber., 9, 468. 

"Kwasnick, Ber., 24, 81. 

3 Wallach, Ann. Chem., 281, 127; compare Ann. Chem., 264, 12. 

*L. Tschiigaeff, Ber., 33, 735. 

178 



CARVONE HYDROGEN SULPHIDE. 179 

sodium, d-carvone yields dihydrocarveol, which is then con- 
verted into methyl dihydrocarvyl xanthate, C 10 H 17 O-CS 2 CH 3 ; 
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. 1 When terpineol 
nitrosochloride is heated with an alcoholic solution of sodium ethy- 
late, oxydihydrocarvoxime, C 10 H 15 (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, 2 C 10 H 15 O(OH), is obtained ; the latter yields 
an oxime, which is converted into inactive carvone by warming 
with dilute sulphuric acid. 

Pinole tribromide, 3 C 10 H 17 OBr 3 , and isopinole dibromide, 3 
C 10 H 16 O -Br 2 , 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. 4 

PROPERTIES. Pure carvone, regenerated from the hydrogen 
sulphide compound, boils at 223.5, and has the specific gravity 
0.9598 at 0. 5 

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, 6 carvacrol is produced quanti- 
tatively by heating carvone with formic acid in a reflux apparatus. 

Carvone hydrogen sulphide, 

OH 
SH 

iWallach, Ber., 28, 1773; Ann. Chem., 291, 342. 
sWallach, Ann. Chem., 291, 342. 
Wallach, Ann. Chem., 306, 273. 

Macheleidt, Inaug. Diss., Gottingen, 1890; Wallaf'" 
224. 

s A. Beyer, Ber., 16, 1387; Schreiner, Pharm. P 
* A. 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 recrystallization from a mixture l of chloroform and 
alcohol, or better from glacial acetic acid ; it separates from the 
latter solvent in long needles, 2 and melts at 187. The melting 
point 210 has also been frequently reported for this com- 
pound. 3 

Hydrochlorocarvone, C 10 H 14 O HC1, was first prepared by Varreu- 
trap. Goldschmidt and Kisser 4 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 zinc 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 5 ). 

Hydrobromocarvone, C 10 H 14 O-HBr, was obtained by Gold- 
schmidt and Kisser 6 as a thick oily compound by treating carvone 
with hydrogen bromide. According to Baeyer, 7 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.nui desiccator, when hydrobromocarvone is deposited in 
crystalline masses ; these are pressed on a porous plate at a low 

'A. Beyer, Arch. Pharm., 221, 283. 

^.heleidt, Inaug. Diss. Gottingen, 1890. 

rel & Co., Semi-Annual Report, April, 189S, 47; see also Glaus 
Journ. pr. Chem., 39. 365. 
and Kisser, Ber., 20, 488. 

oc. 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, 1 when hydrobromocarvone is dissolved 
in methyl alcohol and is reduced with zinc dust, about one-quarter 
of the product is carvone, while the remainder consists of a ketone, 
d 6 -menthene-2-one, C 10 H 16 O, which is isomeric with dihydro- 
carvone. 

Hydrobromocarvone dibromide, C 10 H 14 O HBr Br 2 , 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 ethyl acetate ; it separates in splen- 
did, well defined, monoclinic crystals, which melt at 74 to 76 
(Wallach 2 ). 

When an amyl alcoholic solution of the liquid active, or crys- 
talline inactive, tribromide is saturated with dry ammonia, am- 
monium bromide and a keto-amine, 3 C 10 H 13 O NH 2 , are formed : 

C 10 H ls OBr Br a -f 4NH 3 = 3NH 4 Br + C 10 H 13 ONH 2 

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-oxime, C 10 H 13 (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 10 H 13 ONH 2 . HC1, 
is submitted to dry distillation, hydrogen chloride is eliminated 
and a solid amine, C 10 H 15 ON, results ; this base separates from 

Carries, Ber., 34, 1924. 

2 Wallach, Ann. Chem., 286, 119. 

a Wallach, Ann. Chem., 286', 119; 305, 245. 



182 THE TEKPENES. 

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 10 H U O 2 (carvenolide), ammonia being eliminated : 

C 10 H 18 ONH 2 + H 2 = NH 3 + C 10 H U O 2 . 

Carvenolides, C 10 H 14 O 2 . 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 cc. 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 cc. 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, [o]^ = 138.5. It unites 
with one molecule of bromine, forming a dibromide, C 10 H 14 O 2 Br 2 , 
which crystallizes from ethyl acetate, melts at 97 to 99, and is 
levorotatory, [a\ D = 67.05. 

L-d-Carvenolide is prepared as above described from levo-carv- 
one ; it melts at 41 to 42, and is dextrorotatory, [a]^= + 
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 10 H 16 O 3 . These acids are formed by heating 
the carvenolides with a large excess of a solution of sodium rneth- 
ylate, for eight or nine hours, on the water-bath. D-d-Carvenolic 
acid is produced from D-1-carvenolide, which is obtained from 
dextro-carvone ; it melts at 133, and has the specific rotatory 
power, [a\ D = -f 178.7. L-1-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 BICHLORIDE. 183 

the corresponding carvenolides, and in a glacial acetic acid solu- 
tion they add bromine. 

When D-d-car venolic acid is fused with potash, it gives rise to 
some volatile, liquid acids, together with a solid acid, C 7 H 10 O 2 ; this 
is volatile with steam, melts at 130 to 131, and is levorota- 
tory, [a] D = 2.04. It is an unsaturated compound, and adds 
bromine, forming a dibromide, C 7 H 10 O 2 Br 2 , which melts at 150. 

Carvenolic acid is oxidized by chromic acid or nitric acid, yield- 
ing in each case the same monobasic acid, C 7 H 10 O 4 , which melts 
at 201 to 202. 

Carvone tetrabromide ? C, H 14 OBr 4 , is obtained by the careful 
addition of 6.6 cc. of bromine to a cold solution of ten cc. of 
dextro- or levo-carvone in ten cc. 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 /9-tetrabromide is recry stall ized 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 1 ). 

Inactive /9-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 /9-Carvone pentabromide, C 10 H 13 Br 5 O, is obtained by treat- 
ing a- or /3-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 to 126. The active 
/9-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 zinc dust and glacial acetic acid in the cold (Wallach 2 ). 

Carvone dichloride, 3 C 10 H 14 C1 2 , is formed by the action of phos- 
phorus pentachloride on carvone ; it is an oil, having the specific 

1 Wallach, Ann. Chem., 286, 119. 

2 Wallach, Ann. Chem., 219, 390; 286, 120. 
sKlages and Kraith, Ber., 32, 2550. 



184 THE TEKPENES. 

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 
carvone by adding the latter to phosphorus pentachloride or pen- 
tabromide covered with a layer of petroleum ether. 

When carvone is reduced with alcohol and sodium, one double 
linkage in the molecule becomes single by the addition of hydro- 
gen, and an alcohol, dihydrocarveol, 1 C 10 H 17 OH, results : 

C 10 H U + 4H=,C ]0 H 17 OH. 

In a similar manner, dihydrocarvylamine, 2 C 10 H 17 NH 2 , corre- 
sponding to dihydrocarveol, and not the base, C 10 H 15 NH 2 , is 
formed by treating carvone with ammonium formate (Leuck- 
hart). 

Goldschmidt and Kisser 3 obtained a hydrazone by the action of 
phenylhydrazine on carvone; according to Baeyer, 4 it melts at 
123 to 124. 

CABVOXIME AND ITS DERIVATIVES. 

Carvoxime, C 10 H 14 . NOH, was first prepared by Goldschmidt 5 by 
the action of hydroxylamine on dextrorotatory carvone. Tilden 6 
had previously obtained a compound, C 10 H 14 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 7 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- 

1 Wallach, Ann. Chem., 275, 110; compare Leuckart, Ber., 20, 114, and 
Lampe, Inaug. Diss. Gb'ttingen, 1889. 

* Wallach, Ann. Chem., 275, 119; Leuckart and Bach, Ber., 20, 105; 
Lampe, Inaug. Diss. Gottingen, 18S9. 

8 Goldschmidt and Kisser, Ber., 20, 2071. 

Baeyer, Ber., 27, 811. 

s Goldschmidt, Ber., 17, 1577. 

e Tilden, Jahresb. Chem., 1877, 429. 

7 Wallach, Ann. Chem., 245, 256 and 268; 246, 226; 270, 171. 



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 /3-limonene nitroso- 
chlorides are identical. 

3. Optically inactive carvoxime (m. p. 93) is obtained by the 
elimination of hydrochloric acid from a- and /3-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 10 H 14 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 
Meniha crispa. 

Wallach l 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 j 

> Wallach, Ann. Chem., 275, 118; 277, 133. 



186 



THE TEKPENES. 



W 

.J 
- 

H 




OPTICALLY ACTIVE CARVOXIME. 



187 




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 
/9-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-product 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. 1 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 10 H 17 NH 2 , is formed ; this is the same base that is 
obtained by the treatment of carvone with ammonium formate by 
Leuckart's method (Wallach 2 ). 

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 3 ). The 
formation of this amine is probably preceded by a conversion of 

1 Goldschmidt, Ber., 17, 1577 and 2072; 18, 1729. 

2 Wallach, Ann. Chem., 275, 119. 
3 Wallach, Ann. Chem., 279, 369. 



OPTICALLY ACTIVE CARVOXIME. 189 

carvoxime into cymylhydroxylamine, which is analogous to the 
transformation of carvone into carvacrol : 



1 ' NH OH 





C 3 H T 
Carvacrol. Carvoxime. Cymylhydroxylamine. 

The investigations of Friedlander l and Gattermann 2 have 
shown that the aromatic hydroxylamines are instantly converted 
into the isomeric para-am ido-phenols. In an analogous manner 
cymylhydroxylamine must be converted into para-amidothymol : 





C.H, C 3 H 7 

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 J 1 - 
terpen-8-ol, we ascribe to carvone the formula, 

EL 



H 



H 



then we must consider that the transformations into carvacrol 
and p-ainidothymol are accompanied by transpositions of the 
double linkage. 

1 Friedlander, Ber., 26, 177; 27, 192. 

2 Gattermann, 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, 1 
or when carvoxime is heated with concentrated aqueous potash at 
230 to 240 . 2 In both cases carvacrylamine, C 10 H 13 NH 2 , is 
produced, probably by the reduction of the primarily formed 
cymylhydroxylamine : 





Inactive carvoxime, C 10 H 14 -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. 3 It is further formed as a by-product, together with 
carvacrol and hydroxylamine, when isocarvoxime (m. p. 142) is 
boiled with dilute sulphuric acid. 4 It is more sparingly soluble 
in all solvents than the active carvoximes, and possesses the same 
molecular weight as these. 3 It melts at 93. Its chemical be- 
havior is the same as that of active carvoxime. 

According to investigations of Roozeboom 5 on the solidifying 
points of mixtures of d- and 1-carvoxime, inactive carvoxime 
is not a racemic compound, but is a pseudo-racemic mixed 
crystal. 

Isocarvoxime, C 10 H H NOH, was prepared by Goldschmidt 4 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, 

iWallach, Ann. Chem., 275, 118. 

Wallach, Ann. Chem., 279, 369. 

'Wallach, Ann. Chem., 246, 227. 

Goldschmidt, Ber., 20, 2071. 

5 Roozeboom, Proc. K. Akad. Wetensch. Amsterdam, 1899, 2, 160. 



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 1 ). 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-isocarvoxime, C 10 H 14 NO - CO NHC 6 H 5 , which melts at 
150 . 2 

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 3 ). 

Benzoylcarvoxime, C 10 H 14 NOCOC 6 H 5 , 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, 4 
prepared from the active compounds, melts at 105 to 106. 
Carvoxime is regenerated by treating benzoyl carvoxime with 
sodium alcoholate (Goldschmidt 5 ). 

Carbanilidocarvoxime, C 6 H 5 NH-CO-ONC 10 H 14 , is the addition- 
product of dextro-carvoxime and phenylisocyanate ; when recrys- 
tallized from benzene it forms splendid, brilliant prisms, which 
melt at 130 (Goldschmidt 2 ). 

Hydrochlorocarvoxime, C 10 H, 5 C1NOH, is obtained when a solu- 
tion of carvoxime in methyl alcohol is saturated with hydrogen 
chloride (Goldschmidt 6 ). It may also be prepared by treating 
hydrochlorocarvone with hydroxylamine (Goldschmidt and 
Kisser 6 ), or by passing hydrochloric acid gas through an alco- 
holic solution of - or /9-limonene nitrosochloride (Wallach 7 ) ; 
compare Baeyer. 1 The optically active modifications crystallize 
from petroleum ether in transparent, lustrous prisms or tablets, 
which melt at 135 ; 7 Baeyer 1 found the decomposition point 
(171) to be characteristic for this compound. 

1 Baeyer, Ber., 29, 3. 

2 Goldschmidt, Ber., 22, 3104. 
'Wallach and Neumann, Ber., 28, 1160. 
'Wallach, Ann. Chem., 252, 149. 
BGoldschmidt, Ber., 18, 1732. 
^Goldschmidt and Kisser, Ber., 20, 488. 
7 Wallach, Ann. Chem., 210, 178. 



192 THE TERPEXES. 

Racemic 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, 3 inactive hydrochlorocarvoxime is also formed 
when isocarvoxime, 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 10 H 15 C1 NOCOC 6 H 5 , 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 10 H 15 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 2 ). Accord- 
ing to Baeyer, 3 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, 4 C, H 15 (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 

1 Goldschmidt, Ber., 18, 2222; compare Wallach and Macheleidt, Ann. 
Chem., 270, 179. 

"Goldschmidt and Kisser, Ber., 20, 2071. 

3 Baeyer, Ber., 29, 3. 

<C. Harries, Ber., 31, 1810; Harries and Mayrhofer, Ber., 32, 1345; see 
Wallach and Schrader, Ann. Chem., 279, 366. 



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 10 H 14 (NOH) 2 , 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 10 H 16 N 2 O 2 , melting at 153 to 155, is 
obtained from the mother-liquors of the dioxime. 

The diketone, C 10 H 14 O 2 , results by boiling the dioxime with 
dilute sulphuric acid ; it crystallizes in large prisms, and melts at 
194. This compound 1 (l-methyl-4-propenyl-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, 

C 10 H M = N NHCO-NHj, 

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 2 ). 

Carvone semioxamazone,* C 10 H 14 = N C 2 O 2 N 2 H 3 , crystallizes 
in aggregates of white needles, and melts at 187 to 188. 

Benzylidene carvone, 4 C 10 H 12 O = CH-C 6 H 5 . Benzaldehyde con- 
denses with carvone in the presence of sodium methylate, form- 
ing a solid product, which does not cystallize well. 

Sodium carvonedihydrodisulphonate, 5 C 10 H ]4 O Na 2 H 2 S 2 O 6 , 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. f* 8 *!^ 

Carvone does not yield a normal compound with acid sodium 
sulphite. 

1 Harries, Ber., S4, 2105. 
2Baeyer, Ber., 27, 811 and 1923; 28, 640. 
"Kerp and Unger, Ber., 30, 585. 
*Wallach, Ber., 29, 1595; Ann. Chem., 505, 274. 
H. Labbe, Bull. Soc. Chim., 23, 1900 (III.), 280. 
13 



194 THE TERPENES. 

Carvone combines with aceto-acetic ester and hydrochloric acid, 
forming a compound, 1 C 16 H 25 C1O 4 , melting at 146. 

Oxymethylene carvone, C 10 H 12 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 2 ). 



Reduction Products of Carvone. 

When carvone is reduced by means of zinc dust and acetic acid, 
zinc and sodium hydroxide, or alcohol and metallic sodium, dihy- 
drocarvone, C 10 H 16 O, is formed, together with a crystalline com- 
pound, C 20 H 30 O 2 , which was at first regarded as a pinacone, 3 

C 10 H 14 (OH)-(HO)C 10 H U . 

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 /3-modifications, 
and three ^-modifications ; only the a-modifications result by the 
direct reduction of carvone. 

a-Dicarvelones, C 20 H 30 O 2 . These compounds L 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 cc. 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. 

1 Goldschmidt and Kisser, Ber., 20, 489. 
zWallach, Ber., 28, 32. 

3 Wallach and Schrader, Ann. Chem., 279, 379. 

* Wallach, Ann. Chem., 305, 223; compare Harries and Kaiser, Ber., 31, 
1807. 



f-DICABVELONES. 195 

a-Dicarvelone crystallizes in splendid, rhombic crystals, and the 
two active modifications melt at 1 48 to 149 . D-a-1-Dicar velone, 
prepared from dextro-carvone, is levorotatory, [a]^ = 73.92, 
and L-a-d-dicarvelone from levo-carvone is dextrorotatory, [a]^ 
= + 73.28. A racemic, inactive a-dicarvelone is obtained by 
crystallizing together molecular quantities of D-a-1- 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 20 H 30 (N 2 HC 6 H 5 ) 2 ; the hydrazones of the 
active modifications melt and decompose at 215, and the inactive 
hydrazone decomposes at about 200. 

a-Dicarvelonoxime, C 20 H 30 (NOH) 2 , 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 20 H 30 O 2 -2HBr. a-Dicarvelone 
contains two ethylene linkages, and unites with two molecules of 
hydrogen bromide. The D-a-1-dicarvelone dihydrobromide sepa- 
rates from alcohol in white crystals, and melts at 165. 

/9-Dicarvelones, C 20 H 30 O 2 . 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 ft-dicarvelone. 
D-a-1-Dicarvelone dihydrobromide yields a dextrorotatory /9-modi- 
fication, [a]^ = -f 79.18, and L-a-d-dicarveloue gives rise 
to L-/3-l-dicarvelone, [a]^ = 82.66 ; both active modifica- 
tions crystallize well, and melt at 207. By the union of 
D-/9-d- and L-/9-l-dicar velone, an inactive derivative is produced, 
which melts at 168. The /3-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. 

T'-Dicarvelones, C 20 H 30 O 2 . These compounds are prepared by 
adding the a- or /9-dicarvelones, in small portions at a time, 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-f-1-Dicarvelone, 
prepared from D-a-1- or D-/9-d-dicarvelone, is levorotatory, 
[a]j= 213.4 and 201.8, respectively; L-^-d-di car ve- 
lone is dextrorotatory, [a]^ = -f 236.8. Both active modi- 
fications melt at 126, and the inactive ^-derivative melts at 
112. 



196 THE TERPENES. 

The f-dicarvelones differ from the corresponding a- and j$- 
compounds in that they do not form phenylhydrazones. 

Dieucarvelone, C 20 H 30 O 2 . 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^Oj, 
dieucarvelone, melting at 172, has been isolated and studied; 
the same compound is likewise produced in the reduction of eu- 
carvone, C 10 H U O, with sodium hydroxide and zinc. 

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 20 H 30 O 2 , 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 f- 
dicarvelone, melting at 112. 

The behavior of carvone towards potassium permanganate has 
been studied by Best, 1 and by Wallach, 2 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 oxyterpenylic add, C 8 H 12 O 5 , melting at 192.5 ; when this 
acid is distilled under diminished pressure, it loses water and 
yields a neutral compound, C g H 10 O 4 (diladone), melting at 129. 
According to Best, oxyterpenylic acid is reduced by hydriodic 
acid to terpenylic acid, melting at 55 to 56. According to 
Schryver, 3 terpenylic acid has the constitution of a lactone of 
diaterpenylic acid: 

(CH S ) 2 C O (CH 3 ),COH 

HOCO CH S CH CH 2 CO HOCO CH 2 CH CH 2 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. 4 ) 

'O. Best, Ber., 27, 1218 and 3333. 
2 Wallach, Ann. Chem., 275, 155; Ber., 27, 1496. 

Schryver, Journ. Chem. Soc., 63, 1327; Mahla and Tiemann, Ber., 29, 
928. 

<Tiemann and Semmler, Ber., 28, 2141. 



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. 



Compounds of the Caryone 
Series. 


Prepared from 


Observer. 


Dextro-car- 
vone or levo- 
limonene [a]/) 


Levo-carvone 
or dextro- 
limonene [o] z) _ 


Carvone, 


-(-62.00 


62.00 


A. Beyer, Arch. Pharm., 

ggl, 283. 


Carvone hydrogen sul- 
phide, 


+ 5.53 


5.55 


A. Beyer, Arch. Pharm., 
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- 
voxime, 


10.58 


+ 9.92 


Macheleidt, Ann. Chem., 
270, 179. 



2. CARVEOL METHYL ETHER, C 10 H 15 OCH 3 . 

When carvone, C 10 H 14 O, is reduced in an alcoholic solution 
with sodium, dihydrocarveol, C, H 17 OH, is formed. An alcohol, 
C 10 H 15 OH, corresponding to carvone is not at present known, 
although the methyl ether of carveol, C 10 H 15 OCH 3 , 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 10 H 14 BrOCH 3 ; 
it is volatile with steam, boils at 137to 140 under 14 mm. 
pressure, has the specific gravity of 1.251 and the coefficient of 
refraction, n_p = 1.51963, at 18 (Wallach 1 ). 

If a solution of forty-two grams of this compound, C 10 H 14 BrO- 
CH 3 , in two hundred cc. 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 n^ = 1.47586 at 
18, from which a molecular refraction is calculated that indicates 
the presence of two double linkages in the molecule. The ether 

iWallach, 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. 




H,C CH, 
Terpineol (solid). 





Terpineol dibromide. 



CBr 

H 3 C CH, 

1, 2, 8-Tribromoterpane. 





H,C CH, 

Carveol methyl ether. 



3. EUCARVONE, C 10 H 14 O. 

According to Baeyer, 2 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. 



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 10 H 14 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, 1 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 cc. of hot water. 
A concentrated solution of fifty grams of sodium 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- 

i Wallach, 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 methyl 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, 1 C 10 H 14 = N-NH-CO-NH 2 , crystal- 
lizes in concentric aggregates of prisms, and melts at 183 to 
185. 

Condensation-products of eucarvone and benzaldehyde. 2 Benzyli- 
dene eucarvone, C 6 H 5 CH = C 10 H 12 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 24 H 24 O 2 , 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, 3 C 20 H 30 O 2 , is formed in the reduction of eucarvone 
with sodium hydroxide and zinc; it melts at 172. (See under 
carvone.) 

Eucarvone yields dihydroeucarveol, C 10 H 17 OH, when it is re- 
duced in alcoholic solution with sodium. 1 

Unsymmetrical or <7em 4 -di methyl succinic acid is formed, to- 
gether with a considerable quantity of acetic acid, by the oxida- 
tion of eucarvone with a permanganate solution (Baeyer 5 ). 

An alcohol, C 10 H 15 OH, corresponding to eucarvone is not 
known. 



r, Ber., 27, 1922. 
*Wallach, Ber., 29, 1600; Ann. Chem., 805, 242. 
'Wallach, Ann. Chem., 305, 242. 
Baeyer, Ber., 81, 2067. 
s Baeyer, Ber., 29, 3. 



PINOCARVOXIME. 201 

4. PINOCARVONE, C 10 H 14 O. 

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 1 has changed its 
name to pinocarvone. The corresponding alcohol, C 10 H ]5 OH, was 
called " isocarveol" but is now designated as pinoearveol. 

When pinylamine nitrate is heated with a solution of sodium 
nitrite, an alcohol, C 10 H 15 OH (pinoearveol), is produced ; the latter 
yields pinocarvone by oxidation with chromic acid (Wallach 2 ). 

A solution often grams of pinoearveol 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 pinoearveol 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 10 H 14 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. 

1 Wallach, Ann. Chem., 800, 286. 

* Wallach, Ann. Chem., 277, 150; 279, 387. 



202 THE TERPENES. 

Pinocarvone semicarbazone, 1 C 10 H 14 = N-NH-CO-NH 2 , is spar- 
ingly soluble, and does not crystallize well. It separates from 
aqueous methyl alcohol in slightly yellowish crystals, and melts at 
204. 

5. PINOCARVEOL, C 10 H 15 OH. 

Pinylamine, C 10 H 15 NH 2 , obtained by the reduction of nitroso- 
pinene, may be converted into a secondary alcohol, C 10 H 15 OH, 
which is called pinocarveol because of its relation to pinocarvone. 

Pinocarveol is prepared according to the following method 
(Wallach 2 ). 

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, 10 H 15 OH. 

According to Genvresse, 3 a terpene alcohol, C 10 H 15 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 10 H 15 O-COCH 3 , has an odor recalling that of 
lavender, and boils at 150 under 40 mm. pressure. 

1 Wallach, Ann. Chem., 800, 286. 

2 Wallach, Ann. Chem., 277, 149; 800, 286. 
"P. Genvresse, Compt. rend., 130, 918. 



LIMONENOL. 203 

7. PINENONE, C 10 H 14 O. 

Pinenone 1 is the ketone corresponding to pinenol, C 10 H 16 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, [] 1) = 21.12. Its refractive index is n D = 1.5002, 
giving the molecular refraction 44.33 ; the calculated 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 10 H 14 :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, [aj^, = 22.3. 

The dibromide, C 10 H 14 (NOH) Br 2 , melts at 152. The phenyl 
carbimide, C 10 H 14 -NO-CO-NHC 6 H 5 , crystallizes in needles, and 
melts at 135. The benzoyl and butyryl derivatives melt at 105 
and 74, respectively. 

Pinenone semicarbazone, C 10 H 14 =N NH- CO- NH 2 , melts at 
82. 

8. LIMONENOL, C 10 H ]5 OH. 

This alcohol 2 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, n /) =1.497, and a rotatory power, [] J) =-|-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 10 H 14 O. 

>P. Genvresse, Compt. rend., ISO, 918. 
2 P. Genvresse, Compt. rend., 132, 414. 



204 THE TERPENES. 

9. LIMONENONE, C 10 H 14 O. 

Limonenone 1 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, n^, = 1.487, and the 
specific rotatory power [a] J) = + 16 4'. Its molecule contains 
two double linkings. 

Limonenonoxime, C 10 H 14 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] i) = 39 42', and their benzoyl 
derivatives (m. p. 95), and phenylcarbimides (m. p. 133) agree 
in properties. 

10. SABINOL, C 10 H 15 OH. 

The chemists of Schimmel & Co. 2 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 10 H 17 OH, but more recent investigations of Fromm 3 and 
Semmler 4 indicate that its formula is C 10 H 15 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. 

*P. Genvresse, Compt. rend., 182, 414. 

1 Schimmel & Co., Semi-Annual Report, Oct., 1895, 44. 

3 E. Fromm, Ber., 31, 2025. 

F. Semmler, Ber., 33, 1455. 









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, fj. D = 1.488, and a mo- 
lecular refraction, M = 46.5. 

Sabinol absorbs bromine, iodine, and hydrogen chloride forming 
oily addition-products. 

Semmler 1 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 10 H 14 O, on oxidation. 

It is converted into thujone (tanacetone) by distillation with 
zinc dust, and, when boiled with absolute alcohol and a few drops 
of sulphuric acid, it gives rise to cymene. 

Sabinol acetate, C 10 H 15 O-COCH 3 , boils at 222 to 224. 

Sabinyl glycerol, C 10 H 15 (OH) 3 , results on the oxidation of sabinol 
with aqueous potassium permanganate at ; it crystallizes from 
water, and melts at 152 to 153. Upon warming with water 
containing a trace of acid, it is converted into cuminyl alcohol, 
C ]0 H 13 OH. 

When further oxidized with permanganate, sabinol forms tan- 
acetogendicarboxylic acid, C 9 H 14 O 4 . 

On reduction with sodium and amyl alcohol, sabinol yields 
thujyl alcohol, C 10 H 17 OH, which is readily oxidized to thujone. 

1 Semmler, Ber., 34, 708. 



B. SUBSTANCES CONTAINING ONE ETHYLENE LINK- 
AGE. KETONES, C 10 H 16 0, ALCOHOLS, C 10 H 17 OH, 
AND OXIDES, C 10 H 16 O. 

1. DIHYDROCARVONE, C 10 H 16 O. 

Dihydrocarvone is a ketone which has not yet been observed 
in nature. It was obtained almost simultaneously by Wallach and 
Kerkhoff, 1 and by Baeyer 2 through the oxidation of dihydrocar- 
veol, C W H 17 OH, with chromic anhydride. Wallach and Schrader 8 
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 zinc dust and acetic acid. 

Dihydrocarvone is prepared from dihydrocarveol l 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 cc. 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 cc. 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. 

1 Wallach and Kerkhoff, Ann. Chem., 275, 114. 

2 Baeyer, Ber., 26, 823. 

>Wallach 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. 1 

PROPERTIES. 2 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 (Baeyer 3 ). The same transformation re- 
sults by boiling dihydrocarvone with dilute sulphuric acid (Wal- 
lach 4 ), or with formic acid. 5 Carvenone is also formed when a 
solution of dihydrocarvone in petroleum ether is saturated with 
hydrogen bromide ; 6 a small quantity of a bromine derivative is 
formed during this reaction, and it may be completely converted 
into carvenone on treatment with zinc 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 10 H 18 (OH) 2 , 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 7 ). 

Bromine reacts with dihydrocarvone hydrobromide, forming 
dihydrocarvone dibromide (Baeyer). 

1 Harries, Ber., 84, 1924. 

2 Kondakoff and Lutschinin, Journ. pr. Chem., 60 (II), 257. 
a Baeyer, Ber., 27, 1921. 
* Wallach, Ann. Chem., 279, 388. 

5 Klages, Ber., 82, 1516; compare Kondakoff and Lutschinin, Journ. pr. 
Chem., 60 (II), 257. 

6 Kondakoff and Gorbunoff, Journ. pr. Chem., 56, 248. 
7 Baeyer, Ber., 28, 1589. 



208 THE TERPENES. 

Dihydrocarvone hydrochloride, 1 C 10 H 16 O-HC1, 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, n 7) = 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 10 H 15 C1, 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, n^= 1.51622, at 
18. It is possibly identical with the chloride obtained by a 
similar treatment of carvenone. 

Dihydrocarvone dibromide, C 10 H 15 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 3 ). 

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 cc. 
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 4 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- 
com pound. 

'Kondakoff and Gorbunoff, Journ. pr. Chem., 56, 248. 
*Klages and Kraith, Ber., 32, 2550. 
s Wallach, Ann. Chem., 286, 127. 
* Baeyer, 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, 1 C 10 H 16 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. 1.23) ; 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 oxycarone, 
C 10 H 16 O 2 . When it is recrystallized from methyl alcohol, a small 
quantity of an isomeric compound, melting at 136 to 138, 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 10 H 16 (OH) 2 O, melting at 78 to 80. 

Dihydrocarvone tribromide, C 10 H 15 OBr 3 , 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 2 ). 

Dihydrocarvone dichloride, C 10 H 15 C1O-HC1, 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 3 ). 

Dihydrocarvoxime, C 10 H 16 NOH, was prepared by Wallach and 
Kerkhoff. 4 A warm solution of six grams of hydroxylamine 
hydrochloride in six cc. of water is added to the warm solution of 
six cc. of dihydrocarvone in twenty-five cc. 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, 5 which separates in more difficultly soluble needles, 
is always formed, together with the oxime crystallizing in prisms. 

1 Baeyer and Baumgartel, Ber., 31, 3208. 

2 Wallach, Ann. Chem., 286, 127. 
sfiaeyer, Ber., 28, 1589. 

4 Wallach and Kerkhoff, Ann. Chein., 275, 116. 
5 Wallach, 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 115toll6 

Dihydrocarvoxime hydrobromide, C 10 H 17 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 1 ) ; according to Baeyer, 2 it melts at 118 
to 120. 

According to Wallach, 1 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 : 

C 10 H 17 Br-NOH = H 2 O + C 10 H 13 NH 2 -HBr. 

An oxime, which Baeyer 2 at first called l< 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- 
phuric 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, 1 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, 3 
which he had previously prepared. 

1 Wallach, Ann. Chem., 279, 381. 

2 Baeyer, Ber., 27, 1921. 

s Wallach, Ann. Chem., 277, 126. 



DIHYDROCAKVEOLACETIC ACID. 211 



Semicarbazone of dihydrocarvone, C 10 H 16 = N NH CONH 2 , 
melts atl89tol91. The melting point is not sharp (Wallach 1 ). 

Benzylidene dihydrocarvone, 2 C 10 H 14 O = CH C 6 H 5 , 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, 2 C 10 H 16 (OH) CH 2 C 6 H 5 , 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 17 H 22 , which boils at 
166 to 169 under 10 mm. pressure. 

Oxydihydrocarvone, 3 C 10 H 15 (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 oxime 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 diacdyl derivative, 
melting at 107. Dilute sulphuric acid converts the oxime into 
inactive carvone, while concentrated acid gives rise to amido- 
thymol. 

Dihydrocarveolacetic acid, 4 C 10 H 16 (OH) CH 2 - 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 n^ = 1.47664 at 20. 

The oxymethylene derivative of dihydrocarvone, C 10 H 14 O = 
CHOH, is an oil, boiling at about 115 at 15 mm. pressure 
(Wallach 5 ). 

Dihydrocarvone is converted into a diketone, C 9 H 14 O 2 , on oxi- 
dation with chromic anhydride ; it boils at 152 to 160 under a 
pressure of 22 mm. Its dioxime 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 6 ). This diketone corresponds to the ketone-alcohol, 
C 9 H 16 O 2 , which is obtained by oxidation of dihydrocarveol. 

1 Wallach, Ber., 28, 1955. 
Wallach, Ann. Chem., 805, 268. 
s Wallach, Ann. Chem., 29 1, 342. 
* Wallach, Ann. Chem., 314, 147. 
sWallach, Ber., 28, 33. 
Tiemann and Semmler, Ber., 28, 2141. 



212 THE TEKPENES. 

Wallach and Scharpenack x oxidized dihydrocarvone with dilute 
permanganate solution, and obtained the following products. 

1. A ketone-glycol, C 10 H 16 O(OH) 2 , 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 ]0 H 14 O?), boiling at 220. 

2. A diketone, C 9 H 14 O 2 , 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. Oxalic acid, and an add melting at 203 to 204. 

The reduction of carvone with zinc dust and sodium hydroxide 
yields as a by-product, dicarvelone, C^H^Oj (see under carvone). 

It should also be recalled that the ketone* C 10 H 16 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 10 H 17 OH. 

Leuckart 3 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 4 led to the re- 
sult that it is not carveol, C 10 H 15 OH, as Leuckart had believed, 
but that it has the constitution, C 10 H 17 OH, and must therefore be 
regarded as dihydrocarveol. Lampe's observations have since 
been confirmed by the researches of Wallach, Kruse, and Kerkhoff. 5 

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. 

1 Wallach and Scharpenack, Ber., 28, 2704. 

Wallach, Ann. Chcm., SOO, 291; SIS, 345. 

3Leuckart, Ber., 20, 114. 

4 Lampe, Inaug. Diss. Gottingen, 1889. 

Wallach, Kruse and Kerkhoff, Ann. Chem., 275, 110. 



METHYL DIHYDROCARVYLXANTHATE. 213 

The formation of dihydrocarveol from dihydrocarvylamine is 
mentioned below. 

PEOPERTIES. 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, n^ = 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, 1 when an 
aqueous solution of equal molecular proportions of dihydrocarvyl- 
amine hydrochloride and sodium nitrite is heated. 

Dihydrocarvyl phenylurethane, 



V>r TT 

-"-'lO-H-lT 

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, 2 C 10 H 17 O-CS 2 -CH 3 , 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. 

iWallach, Ann. Chem., 275, 128. 
*L. Tschtlgaefl, Ber., S3, 735. 



214 THE TERPENES. 

Dihydrocarvyl acetate, C 10 H 17 OCOCH 3 , 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 tetrahydrocarvyl 
acetate by reduction with zinc dust and glacial acetic acid ; the 
latter is converted into tetrahydrocarveol, C 10 H 19 OH, by hydrol- 
ysis (Baeyer 1 ). 

Dihydrocarveol hydrobromide, C 10 H 17 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 1 5 mm. ; this acetate may be converted by hydrolysis 
into a glycol, C 10 H 18 (OH) 2 , 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 2 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 10 H 16 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 10 H 16 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 10 H 16 NOH-j- 
H 2 O, one of which melts at 111 to 112, and the other at 164 
to 165. 

Tiemann and Semmler 3 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 9 H 16 O 2 , 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 7 H 13 O COOH, which melted at 1 53 . When heated with bromine 

1 Baeyer, Ber., 26, 821. 

2Wallach, Ann. Chem., 275, 155; 277, 151; 279, 386. 

"Tiemann and Semmler, Ber., 28, 2141. 






DIHYDEOCAKVEOL 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 Willstatter 
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 : 





Trioxyhexahydrocymene 
from dihydrocarveol. 



Methyl-1 -ethyl-on-4- 

cyclohexanol-6 
(m. p. 58 to 59). 




;OOH 

Methyl-l -cyclohexanol-6- 

methyl-acid-4 (m. p. 

153). 




;OOH 

m-Oxy-p-toluic acid. 



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 : 



J? 

2 C CHOH 

r n r 

[2 V 



r/\, 



H,C CH 2 

Dihydrocarveol. 





H 3 C CH 2 
Limonene. 



216 THE TEKPENES. 

These formulas, which are the natural consequence of the 
formula of terpineol founded on the researches carried on by 
Wallach, 1 and, directly following him, by Tiemann and Semmler, 2 
had been presented by G. Wagner 3 one year previous to their 
publication by Tiemann and Semmler. 

3. CARVENONE, C 10 H 16 O. 

Crystallized terpineol (melting point 35) yields a trivalent 
alcohol, C 10 H 17 (OH) 3 , 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 10 H 16 O 
(Wallach 4 ): 

C 10 H 17 (OH) 3 -3H 2 = C 10 H 14 , 
C 10 H 17 (OH) 3 - 2H 2 = C 10 H 16 0. 

Wallach supposed that a monovalent, unsaturated alcohol, 
C 10 H 15 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 10 H 16 O, was subsequently obtained by 
Baeyer, 5 who gave to it the provisional name " carveol." After 
further examination Wallach 6 called it carvenone. 

Carvenone also results when dihydrocarvone is treated with cold, 
concentrated sulphuric acid, and the resulting solution is precipitated 
with ice (Baeyer 5 ) ; or, when dihydrocarvone is boiled with dilute 
sulphuric acid (Wallach 6 ). 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 5 ). 

According to Klages, 7 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 

i Wallach, Ber., 28, 1773. 

aTiemann and Semmler, Ber., 28, 1778. 

sG. Wagner, Ber., 27, 1653 and 2270. 

<Wallach, Ann. Chem., 277, 110 and 122. 

sBaeyer, Ber., 27, 1917. 

eWallach, Ann. Chem., 286, 129. 

7 A. Klages, Ber., 82, 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 1 ). 

According to Bredt, 1 carvenone may be separated from the 
more volatile constituent of " camphrene " 2 (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, n^ = 1.48197. 

Wallach 3 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 n^ = 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. It is converted into carvacrol by boil- 
ing with ferric chloride (Wallach). 

Carvenonoxime,C 10 H 16 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 10 H 20 N 2 O 2 , melting at 162 to 163, is formed, 
together with carvenonoxime, if an excess of hydroxylamine 
hydrochloride be allowed to react with carvenone. 

Carveuone unites with four atoms of hydrogen when it is re- 
duced with sodium and alcohol, and forms tetrahydrocarveol, 
C 10 H ]9 OH (Wallach). This secondary alcohol is identical with 
Baeyer' s carvomenthol, and is an isomeride of position of menthol. 

Carvenone semicarbazone, C 10 H 16 = N NH CO NH 2 , crystal- 
lizes in spindles or six-sided leaflets, melting at 202 to 205 
(Baeyer 4 ). 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 
/3-semicarbazone, melting at 153 to 154. 

Nitrosocarvenone, C 10 H 15 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 

1 Bredt, Rochussen and Monheim, Ann. Chem., S14, 369. 
2 Armstrong and Kipping, Journ. Chem. Soc., 63, 77. 
3 Wallach, Ber., 28, 1955. 
< Baeyer, 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 ; it is purified by precipitating its solution 
in chloroform with methyl alcohol. It melts with decomposition 
at 133, and is to be regarded as a bisnitroso-compound (Baeyer 1 ). 
Condensation-product of carvenone and benzaldehyde. 2 When 
dry hydrogen chloride is passed into a well cooled mixture of two 
molecular proportions of benzaldehyde and one of carvenone, the 
compound, C 24 H 2g O 2 HC1, 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 24 H 26 O 2 , results; it crystallizes from hot methyl alcohol, and 
melts at 170 to 171. 

Oxidation Products of Carvenone. 5 

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-o^-methyl-a-isopropyl adipic acid, C 10 H 18 O 5 , 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 10 H 16 O 4 , melting at about 100. 

2. 2 : 6-Dimethyl-heptan-5-onoic acid, C 9 H 16 O 3 , 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 10 H 18 O 5 . It is a ketonic acid and yields an oxime, C 9 H 16 O 2 (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 9 H 16 O 3 . 

In consideration of these oxidation products, Tiemann and 
Semmler suggest the following formula for carvenone : 







H 3 C 

i Baeyer, Ber., 28, 646. 
2 Wallach, Ann, Chem., 305, 270. 
'Tiemann and Semmler, Ber., 81, 2889. 



CARONE. 219 

It should further be mentioned that Marsh and Hartridge 1 
have described a compound, C, H 16 O, under the name "carvenol "; l 
they prepared it by the action of concentrated sulphuric acid on 
chlorocamphene, C 10 H 16 C1 2 (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 10 H 19 OH, " carvanol," which 
is converted into the ketone, C 10 H 18 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. CAEONE, C 10 H 16 O. 

Carone, like its isomeride carvenone, was obtained by Baeyer 2 
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, a D = 
+ 173.8; levo-carvone yields levo-carone, a JD = 169.5 
(Briihl 3 ). 

It does not combine with acid sodium sulphite ; it is converted 
into carvenone and certain condensation-products by continued 

'March 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. 

"Baeyer, Ber., 27, 1915. 

3Bruhl, 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 caroue, 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 10 H 16 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 2 ). 

The semiearbazones 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 semiearbazones de- 
compose at once into semicarbazide and carone on boiling with 
dilute sulphuric acid. 

Bisnitrosocarone, (C 10 H 15 O) 2 N 2 O 2 , 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 caroue 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- 

1 Baeyer, Ber., 29, 3. 

* Baeyer, Ber., 27, 3485; 28, 640. 



OXYCARONE. 221 

uble in chloroform, and melts with decomposition at 145 
(Baeyer J ). 

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 2 
obtained caronbisnitrosylic acid, C 10 H 15 O-N 2 O 2 -H, together with 
dihydrocarvone dibromide or dichloride. 

The oxymethylene compound of tetrahydrocarvone 2 is formed in- 
stead of the oxymethylene derivative of carone, when carone is 
treated with amyl formate in an ethereal solution. 

Oxycarone, 3 C 10 H 16 O 2 , is produced when one molecule of 1 : 8- 
oxybrornotetrahydrocarvone, C 10 H 16 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 oxime 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 10 H 16 (OH) 2 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 toal:2: 8-trioxyterpane, C 10 H 20 O 3 , 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 
Tcetone of homoterpenylic acid (a keto-lactone), C 10 H 16 O 3 , melting at 
48 to 49. (Compare with the keto-lactone obtained from ter- 
pineol.) 

1 Baeyer, Ber., 28, 641. 
Baeyer, Ber., 28, 1589. 
Baeyer and Baumgartel, Ber., 31, 3208. 



222 THE TERPENES, 



Oxidation of Carone. 1 

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 tis- and rans-modifications ; the latter acid is 
termed caronio acid or ^em-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 adds, 

OH, ,CH COOH 

CH, C \CH COOH 

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 cts-acid in crystals, while the 
trans-acid is separated by conversion into its ammonium salt. 

Cis-caronic acid, C 7 H 10 O 4 , 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 7 H 10 O 4 , 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 cts-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, /CH CO CH CH, 

CH S X3H 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. 

1 Baeyer and Ipatieff, Ber., 29, 2796 ; Baeyer and Villiger, Ber., SI, 1401 ; 
Perkin and Thorpe, Proc. Chem. Soc., 1898, 107 ; Baeyer and Villiger, Ber., 
SI, 2067. 



NITEOSODIHYDROEUCARVONE. 223 



5. DIHYDROEUCARVONE, C 10 H 16 O. 

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 1 ). It is unstable towards 
permanganate, and yields an oily oxime, which forms a very 
characteristic, crystalline hydriodide. 

Dihydroeucarvoxime hydriodide, C 10 H 17 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 10 H 17 NH 2 ; but on 
reduction with zinc dust and alcoholic hydrochloric acid, it is con- 
verted into tetrahydroeucarvone, 2 C 10 H 18 O. 

Dihydroeucarvone semicarbazone, C 10 H, 6 =N-NH-CO-NH 2 , crys- 
tallizes in thin plates ; it is readily soluble in alcohol, and melts 
at 189 to 191. 

Nitrosodihydroeucarvone, C 10 H 15 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. 3 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 10 H 15 O) 2 N 2 O 2 . 

According to Baeyer, 2 dihydroeucarvone is a methyl-^em-di- 
methylcycloheptenone, and, when oxidized with a saturated solu- 
tion of potassium permanganate, it gives rise to unsymmetrical or 
^em-dimethylsuccinic acid. Baeyer regards this as evidence of the 
presence of the ^ewt-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 10 H 15 C1, is formed, which boils at 92 to 93 under 
18 mm. pressure, and has a sp. gr. 1.02 and refractive index, 
no = 1.51250, at 18. 

1 Baeyer, Ber., 27, 1922. 

2 Baeyer and Villiger, Ber., 81, 2067. 
a Baeyer, Ber., 27, 1923; W 646. 



224 THE TEKPENES. 

6. DIHYDROEUCARVEOL, C 10 H 17 OH. 

Dihydroeucarveol is formed when eucarvone, C 10 H U O, or dihy- 
droeucarvone, C 10 H 16 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. 1 

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, 2 C 10 H 17 O COCH 3 , boils at 223 to 
224, and has a sp. gr. 0.951 and a refractive index, n^ = 1.46315, 
at 20. 

Dihydroeucarvyl chloride, 2 C 10 H 17 C1, 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, 3 C 10 H 16 , is produced ; this terpene boils at 161 to 165, and 
yields acetic, oxalic and ^em-dimethylsuccinic acids on oxidation 
with permanganate.,*^ 



7. THUJONE (TANACETONE), C 10 H 16 O. 

The investigations of Schweizer 4 and of Jahns 5 determined 
that thuja oil contains a ketone, C ]0 H 16 O. Wallach 6 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 10 H 16 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 7 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 

i Baeyer, Ber., 27, 1922. 

2 Klages and Kraith, Ber., S2, 2550. 

Baeyer and Villiger, Ber., 31, 2067. 

4 Schweizer, Ann. Chera., 52, 398. 

s Jahns, Arch. Pharm. (1883), 221, 748. 

Wallach, Ann. Chem., 272, 109. 

'Semmler, Ber., 25, 3343. 



THUJONE. 225 

Bruylants, 1 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 2 to a constituent 
of the oil of absinth ; he also regarded it as identical with salviol, 
a compound found by Muir and Sigiura 3 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 4 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 5 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 6 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 cc. of a saturated solution of acid sodium 
sulphite, seventy-five cc. of water and three hundred cc. 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 

1 Bruylants, Ber., 11, 450. 

2 Beilstein and Kupfer, Ann. Chem., 110, 290. 
3Muir and Sigiura, Jahresb. Chem., 1819, 980. 
* Wallach, Ann. Chem., 275, 179; 279, 383. 

& Semmler, Ber., 27, 897. 
sWallach, 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, n^ = 1.4495, at 20 (Semmler 1 ). Wallach 2 found similar 
constants. According to Semmler, 3 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 4 ). 

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 10 H 13 OBr 3 , is prepared when five cc. of 
bromine are added in one portion to a solution of five grams of 
thujone in thirty cc. of petroleum ether, contained in a 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 5 ). 

When thujone tribromide is treated with a solution of sodium 
in'methyl 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 5 ) : 

C 10 H 13 OBr 3 -f 2NaOCH 3 = 2NaBr + CH 3 OH + Cw 



1 Semmler, Ber., 25, 3343. 

2 Wallach, Ber., 28, 1955. 

3 Semmler, Ber., 27, 897. 

Wallach, Ann. Chem., 275, 197; 286, 109; see Semmler, Ber., 33, 2454. 
5 Wallach, 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 : 





Methoxy-bromocarvacrol. 



This phenol separates from methyl alcohol in colorless crystals, 
and melts at 156 to 157 ; it forms an acetyl compound, melting 
at 63 to 64, and a methyl ether, melting at 42 to 43 (Wallach 1 ). 

The action of sodium and ethyl alcohol converts thujone tri- 
bromide into an ethoxyl-compound, C 10 H n Br(OH)(OC 2 H 5 ), 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 10 H 17 OH, is formed when thujone is reduced 
with sodium and alcohol. 

An amine, C 10 H 17 NH 2 , 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, 2 C 10 H 16 (OH)-CH 2 COOH, is produced by the 
action of zinc 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 10 H 16 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 

1 Wallach, Ann. Chem, 275, 197; 286, 109. 

2 Wallach, Ann. Chem., 314, 147. 



228 THE TERPENES. 

not identical. Wallach, 1 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 1 ). 

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 1 ). 

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 2 ) ; the same amine is also obtained in a 
similar manner from carvoxime (see page 190). 




Carvacrylamine. 

Thujone semicarbazone, C 10 H 16 =N-NH-CO-NH 2 , forms acute 
prisms, and melts at 171 to 172 (Baeyer 3 ). 

According to Rimini, 4 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- 

1 Wallach, Ann. Chem., 277, 159; 286, 94. 

2 Semmler, Ber., 25, 3352. 
s Baeyer, Ber., 27, 1923. 

*E. Rimini, Gazz. Chim., SO [I], 600. 



/J-THTJJAKETONIC 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 10 H 14 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 1 ). 

The behavior of thujone and tanacetone towards potassium per- 
manganate and towards bromine and sodium hydroxide has been 
carefully studied by Wallach 2 and by Semmler 3 ; 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 /9-Thujaketonic acids (tanacetoketocarboxylic acids), 

xCOCH, 
12 \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, 4 C 10 H 16 O 3 , 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-tanacetogendicarboxylic 
acid, C 9 H 14 O 4 , which melts at 141 to 142. 

/9-Thujaketonic acid 4 (3-metho-ethyl-2-heptene-6-onoic acid), C 10 - 
H lg O 3 , is produced generally in larger quantities than the a-acid ; 

1 Wallach, Ber., 28, 33. 

Wallach, Ann. Chem., 272, 111; 275, 164. 

aSemmler, Ber., 25, 3346 and 3613. 

Wallach, Ber., 30, 423; Tiemann and Semmler, Ber., 80, 429. 



230 THE TEBPENES. 

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 10 H 15 O 3 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 9 H 16 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 3 . Wallach regards the 
/3-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. 

ft - Tanacet ogendicarb oxy lie acid ( 3 -metho-ethyl-2 -hexene-dioic 
acid), C 9 H 14 O 4 , results by the action of alkaline hypobromite on 
/9-thujaketonic (/9-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 9 H U O 4 , 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 9 H 12 O 3 , 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 add, 



CH 2 CH-CH(CH a ) 2 
COOHCOOH 



whilst by the distillation with soda-lime it is changed into tana- 
cetophorone, C g H 12 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, n^, = 1.4817, at 20. By the oxidation of tanaceto- 
phorone with potassium permanganate, a solid lactone, C 7 H 12 O 3 , 
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 g H 14 O 2 , 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 



METHYL HEPTYLENE KETONE. 231 

23 mm., has the specific gravity 0.9402 at 20, and the refractive 
index, n^, = 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 7 H 12 O 3 , 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 /3-tanacetogendicarboxylic acid with potassium 
permanganate. It yields a sparingly soluble silver salt, and an 
oxime, 1 melting at 88 to 89. This acid is identical with ^-di- 
methyl laevulinic acid prepared by Fittig and Silberstein. 2 

2-Methyl-5-isopropylpyrroline, C 8 H 12 NH, is produced by heat- 
ing the diketone, C 8 H 14 O 2 , with alcoholic ammonia in sealed tubes 
at 180, for two hours ; it has the specific gravity 0.9051 at 20, 
the refractive index, n D = 1.4988, and the molecular refraction, 
M = 39.86. 

a- and ^-Thujaketoximic acids (tanacetoketoximic acids), 

,C(NOH) CH, 
C ' H '<COOH 

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 /9-acid melts 
at 104 to 106. The formation of these acids indicates that the 
a- and /3-thujaketonic acids contain a ketone group. The -ke- 
toximic acid yields a hydrochloride, C 10 H 16 O 2 -NOH-HC1, melting 
at 128 to 129, and a hydrobromide, C 10 H 16 O 2 NOH-HBr, which 
melts at 176 to 177. 

Methyl heptylene ketone, C 7 H 13 -CO CH 3 , 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 /3-acid during the distillation. 

It 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, C 9 H 14 , when heated with zinc chloride 
(Wallach). It forms a semicarbazone, 3 which melts at 143. Its 
benzylidene derivative, 5 C 9 H ]4 O = CH-C 6 H 6 , crystallizes in white 
needles, and melts at 170. 

tTiemann and Semmler, Ber., 31, 2311. 

"Fittig and Silberstein, Ann. Chem., 283, 269; Fittig and Wolff, Ann. 
Chem., 288, 176. 

s Wallach, Ber., SO, 423. 



232 THE TERPENE8. 

Tiemann and Semmler 1 describe a compound, C 9 H 16 O, under 
the name tanacetoketone (thujaketone, or 2-methyl-3-metheneheptane- 
6-one) ; they obtain it by the elimination of carbon dioxide from 
/9-tanacetoketonic (thujaketonic) acid, and represent its constitu- 
tion by the formula, 

CH 2 = C(C,H 7 /j) CH 2 CH 2 CO CH 3 . 

It is probably identical with Wallach's methyl heptylene ketone. 

Thujaketoxime (methyl heptylene ketoxime), 2 C 9 H 16 NOH, is 
derived from methyl heptylene ketone, and boils at 118 to 120 
under 15 mm. On reduction, it yields a base, C 9 H 17 NH 2 , 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 9 H 13 NH 2 , 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 7 H 13 -CH(OH)-CH 3 , 
boiling at 185 to 187; it has an odor recalling that of linalool ; 
its specific gravity is 0.848 and specific refractive power, n^ = 
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 9 H 18 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, n^, = 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 SX 

. >CH.C(CH,)=CH-CH 2 CO-CH, 
CH 3 / 

Methyl heptylene ketone. 
CH, V 

^>CH.C(CH,)=CH-CH 2 CH(OH) CH, 

Methyl heptylene carbinol. 



>vyj_i. V/V > ^- LI S) CH 2 CHj CH CHj 

'H 3 / j Q | 

Dimethyl isopropyl butylene oxide. 



1 Tiemann and Semmler, Ber., 30, 429. 
"Wallach, Ann. Chem., 309, 1. 



TANACETOGEN DIOXIDE. 233 

Tiemann and Semmler 1 regard them as having a somewhat 
different constitution. 

According to Wallach, 2 when the alcohol, C 9 H 17 OH, obtained 
by the reduction of methyl heptylene ketone, is oxidized with 
potassium permanganate, a glycerol, C 9 H 17 (OH) 3 , 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 9 H 16 O, which has an odor recalling that of pinole, and 
boils at 160 to 165; its bromine derivative, C g H 15 BrO, crystal- 
lizes from alcohol in white needles, and melts at 124.5. 

According to Tiemann and Semmler, 3 when tanacetoketone 
(thujaketone or methyl heptylene ketone) is oxidized with potas- 
sium permanganate, it yields a small quantity of ^-((w)-dimethyl 
laevulinic methyl ketone ; the chief product, however, is the keto- 
glycol, 2-methyl-3-methyl-ol-heptan-6-one-3-ol, C 9 H 16 O(OH) 2 . 

Tanacetogen dioxide, C 9 H 16 O 2 , 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 10 H 16 O 4 , 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 cc. of a four 
per cent, solution of sodium hydroxide. Any unchanged oil is 
then removed by shaking with ether, the aqueous solution is con- 
centrated and acidified with dilute sulphuric acid ; the acid, 
C 10 H 16 O 4 , 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 

i Tiemann and Semmler, Ber., 28, 2136. 

Wallach, Ber., 30, 423. 

3 Tiemann and Semmler, Ber., SO, 429. 



234 THE TEEPENES. 

liberated and tanacetogenic acid, C 9 H 13 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 l considers it as having 
a diagonal linkage, and proposes the following formula : 



n 

HC CO 



C S H T 
Thujone. 

Wallach 2 gives numerous reasons for not accepting this con- 
stitutional formula. 

Semmler 3 has more recently proposed the following formula 
for thujone : 




8. THUJYL ALCOHOL (TANACETYL ALCOHOL), C 10 H 17 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, n^ = 1.4635, at 
20. It behaves as a saturated compound (Semmler 4 ). 

Semmler, Ber., 27, 898. 

2 Wallach, Ann. Chem., 286, 116. 

3 Semmler, Ber., 33, 275 and 2454. 

Semmler, 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 10 H 17 C1, 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 10 H 16 , 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 10 H 16 O. 

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 1 ). 

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, n^, = 1.48217 at 20 ; it im- 
mediately reduces a cold solution of potassium permanganate, 
thus indicating that it is an unsaturated compound. 

Isothujolacetic acid, 2 C 10 H 16 (OH) CH 2 COOH, melts at 168 to 
170. 

Isothnjonoxime, C 10 H 16 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 1 ). 

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*). 

i Wallach, Ann. Chem., 286, 101. 
* Wallach, Ann. Chem., 314, 147. 
sWallach, Ber., 28, 1955. 



236 THE TERPENES. 

Dihydroisothujol or thnjamenthol, C 10 H 19 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, n^, = 
1.46306, at 20 ; it is not identical with menthol or tetrahydro- 
carveol (carvomenthol) (Wallach 1 ). 

Thujamenthone, C 10 H 18 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 10 H 16 O 3 , 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 semioarbazone melts at 
193, and its oxime at 153. 

Sodium hypobromite converts isothujaketonic acid into iso- 
propyl succinic acid and bromoform (Wallach 2 ). 

When isothujaketonic acid is distilled under atmospheric 
pressure, it is converted into the keto-lactone, C 10 H I6 O 3 , which 
melts at 43 ; its oxime melts at 155. The same keto-lactone is 
also formed on oxidizing thujamenthone with chromic acid. On 
further oxidation, this keto-lactone yields /9-isopropyl laevulinic 
acid (Semmler 3 ). 

10. CARVOTANACETONE, C 10 H 16 O. 

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 4 ). 
Wallach's 5 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 6 ). 

1 Wallach, Ann. Chem., 286, 101. 

2 Wallach, Ber., 30, 423. 

3 Semmler, Ber., 83, 275. 
* Semmler, Ber., 27, 895. 

s Wallach, Ann. Chem., 275, 183; 279, 385. 
e Semmler, 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, n^= 1.4835, at 
17 (Semmler 2 ). Wallach 1 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 10 H 19 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 l researches fully establish Semmler's view. 

Carvotanacetone unites with hydrogen sulphide in ammoniacal 
solution ; 2 the product melts at about 95. 

Carvotanacetoxime, C 10 H 16 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 1 ). 

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 3 ). 

According to Harries, the oxaminoxime of Carvotanacetone 
sinters at 155 and melts at 162; it was not obtained quite 
pure, hence Harries 4 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 2 concludes that Carvotanacetone 
is an or^Ao-terpene ketone, and that the pseudo-ketone corre- 
sponding to it is found in terpenone, 5 C 10 H ]6 O (obtained from 
tetrahydrocarvone). 

11. PULEGONE, C 10 H 16 O. 

The ethereal oils of Mentha pulegium and Hedeoma pidegioides 
Persoon, which are sold under the name of pennyroyal oil, contain a 

i Wallach, Ber., 28, 1955. 

*Semmler, Ber., 27, 895; S3, 2454. 

Baeyer, Ber., 27, 1923; see Harries, Ber., 34, 1924. 

4 Harries, Ber., S4, 1924. 

5 Baeyer and Oehler, Ber., 29, 35. 



238 THE TERPENES. 

ketone, C 10 H 16 O, as their chief constituent ; this ketone was sub- 
jected to a detailed investigation by Beckmann and Pleissner. 1 
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 1 is dextrorotatory, \a\ D = -f- 22.89 ; its specific 
gravity is 0.9323 and refractive index, n^, = 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 2 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 3 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 cc. to sixty cc. of alcohol. 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 10 H 16 O HC1, 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 

Beckmann and Pleissner, Ann. Chem., 262, 1 ; compare Kane, Ann. Chem., 
32, 286 (1839); Butlerow, Jahresb. Chem., 1854, 595; Kremer's Ana- 
lysis of the volatile oil of Hedeoma pulegoides, Cincinnati, 1887. 

"Wallach, Ber., 28, 1955. 

3 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 1 ). 

Pulegone hydrobromide, C 10 H 16 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] 1) = 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 7 H 12 O 
(Harries 2 ). 

Hydrobromopulegonoxime, C 10 H 17 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 10 H 18 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 3 
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 

i Baeyer and Henrich, Ber., 28, 652. 

Harries and Roeder, Ber., 32, 3357. 

'Beckmann, German patent, No. 42458; Ber., 22, 912. 



240 THE TEEPENES. 

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. 

Pulegonoxime, C 10 H 16 NOH. Although Beckmann and Pleiss- 
ner obtained only the " hydrated oxime " from pulegone, Barbier l 
has described a normal pulegonoxime, C 10 H 16 NOH, as an oil, 
which boils at 170 under 48 mm. pressure. "VVallach 2 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 10 H iy NH 2 , results by reducing an alcoholic solu- 
tion of pulegonoxime with sodium (Wallach *). 



BECKMANN AND PLEISSNER'S "HYDRATED PULEGON- 
OXIME," C 10 H 19 NO 2 , 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, [] i) = 83.44. 
Molecular weight determinations indicate that it has the simple 
molecular formula, C 10 H 19 NO 2 . 

'Barbier, Compt. rend., 114, 126; Ber., 25, 110, Ref. 
2 Wallach, Ann. Chem., 277, 160. 
3 Wallach, Ann. Chem., 289, 337. 



PULEGONAMINE. 



241 



The hydrochloride, C 10 H 19 NO 2 -HC1, 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 l crystals, melts at 117 to 118, and is levorotatory, 
\OL\J) 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 10 H 18 O NO 

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 10 H 18 O - NO COCH 3 , melts at 149. 

According to more recent researches of Harries, 2 Beckmann and 
Pleissner's " hydrated pulegonoxime " should be called pulegone 
hydroxylamine; its constitution is expressed by the following 
formula : 



COC 6 H 5 , is prepared by treating 




NH-OH 



Oxidation converts it into nitrosomenthone (m. p. 35) and nitro- 
menthone (m. p. 80). 

Pulegone hydroxylamine forms an oxalate, 3 (C 10 H 19 O 2 N)C 2 O 4 H 2 , 
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, 3 but is ex- 
ceedingly unstable. 

Pulegone hydroxylamine also reacts with hydriodic acid, giving 
rise to 8-amidomenthone. 

Pulegonamine, C 10 H 19 ON, is formed when " Pleissner's oxime " 
is warmed with hydriodic acid and red phosphorus. 



, Ann. Chem., 262, 9. 

2 Harries and Roeder, Ber., SI, 1809. 

3 Harries and Roeder, Ber., 82, 3357. 

16 



242 THE TERPENES. 

Pulegone semicarbazone, 1 C 10 H 16 = N NH-CO-NH 2 , 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 10 H 15 O) 2 N 2 O 2 . According to Baeyer and 
Henrich, 1 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 cc. 
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 2 regards this compound as a bis- 
nitroso-derivative, but it differs from members of this class in 
that it yields an oxime in addition to a bisnitrosylic add; this fea- 
ture is explained by the fact that the bisnitroso-group NO 2 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, 2 C 10 H 15 NO 2 , is prepared by the action of 
caustic soda on bisnitrosopulegone ; it crystallizes in yellow 
needles, and decomposes at 122 to 127. 

Pulegondioxime hydrate, 2 C 10 H lg N 2 O 3 , is formed by the action of 
hydroxylamine on isonitrosopulegone. 

Pulegonbisnitrosylic acid, 2 C 10 H 16 N 2 O 3 , 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, 2 C 10 H 15 C1O, which crystallizes in long needles 
and melts at 124 to 125, and diisonitroso-methyl-cydohexanone, 
C 7 H 1(J N 2 O 3 , 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 3 H 6 -group from the 
pulegone molecule. Its diacetate melts at 125 to 130. The 
diisonitroso-derivative yields the anhydride of triisonitroso-methyl- 
cydohexafione, C 7 H 9 N 3 O 2 , by the action of hydroxylamine ; it melts 
at 128 to 129, and yields an acetate, melting at 139 to 140. 

Benzylidene pulegone, 3 C 10 H U O = CH C 6 H_, is formed by the 
condensation of pulegone and benzaldehyde with sodium ethylate ; 

i Baeyer and Henrich, Ber., 28, 652. 
* Baeyer and Prentice, Ber., 29, 1078. 
sWallach, 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 10 H 16 (OH)- 
CH 2 C 6 H 5 . 

Pulegenacetone, 1 C^H^O, is formed by warming a mixture of 
pulegone, ethyl acetoacetate, and glacial acetic acid with fused 
zinc 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-J 2(4:8) -terpadiene, 2 C 10 H 15 C1, 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 n D = 1.49928. 
With an excess of bromine, it yields a tetrabromide, C 10 H n ClBr 4 . 
Formic acid converts the chloroterpadiene into methyl cyclohex- 
anone. 

Bispulegone, 3 C 20 H 34 O 2 , 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, meuthone and menthol are also formed. 

Oxidation of pulegone. Pulegone yields acetone and optically 
dextrorotatory ^-methyl adipie add, C 7 H 12 O 4 (m. p. 84.5), on 
oxidation with potassium permanganate. 

/9-Methyl adipie acid is converted into a lactonic add, CjH^O^ 
by oxidation ; when the calcium salt of /3-methyl adipie acid is 
distilled with soda-lime, it yields a ketone, C 6 H 10 O, fi-methyl 
ketopentamethylene. According to Semmler, 4 these reactions indi- 
cate that /3-methyl adipie acid has the following constitution : 



HOOC CH 8 CH 2 CH(CH 3 ) CHj COOH 

/3-Methyl adipie acid. 
^* %^ 
CO CH, CH 2 C(CH S ) CH 2 COOH H,C CH CH, 
O Cl 



y-Valerolactone-y-acetic acid. /? -Methyl ketopentamethylene. 



ier, Compt. rend., 127, 870. 
*Klages, Ber., 32, 2564. 
'Harries and Roeder, Ber., 82, 3357. 
*Seminler, Ber., 25, 3515; 26, 774. 



244 THE TERPENES. 

Semmler derives the following constitutional formula of pule- 
gone from these transformations : 




Pulegone. 

This formula has further been proved by Wallach. 1 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 S C CH, 
Pulegone. Methyl cyclohexanone. Acetone. 

The formyl derivative of cycloheptylenamine (hexahydro- 
meta-toluidine), C 7 H 13 NH 2 , is formed in an analogous manner, 
when pulegone is boiled with ammonium formate. 

Methyl cyclohexanone, 1 C 7 H 12 O, is obtained from pulegone as 
above mentioned. It is also formed during the action of concen- 
trated sulphuric acid on pulegone, 2 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. 3 

It boils at 169, has the specific gravity 0.915 at 21, and the 
refractive index, n D = 1.4456, at the same temperature; M= 

i Wallach, Ann. Chem., 289, 337. 
2 Harries and Roeder, Ber., 32, 3357. 
3Zelinsky, Ber., 30, 1532. 



METHYL PTJLEGENATE. 



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 cydohexanol (meta-oxyhexahydrotoluene), C 7 H 13 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. 1 

PULEGENIC ACID, CLH lfi (X. 

ID it) 2. 

Pulegone forms a liquid dibromide, which yields pulegenic acid 
when it is heated with a solution of sodium methylate : 



C 10 H 16 OBr 2 



= 2HBr + C 10 H 16 O 2 . 



This acid boils without decomposition at 150 to 155 under a 
pressure of 13 mm.; when distilled at atmospheric pressure, it 
decomposes into carbonic anhydride and a hydrocarbon, C 9 H 16 . 
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 2 ). 

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, n D = 
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, 3 C 10 H 15 O 2 CH 3 , boils at 89 to 90 (10 mm.), 
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 

1 Wallach, Ann. Chem., 289, 337; 309, 1; 312, 171; S14, 147; Ber., 
29, 1595; 29, 2955; Klages, Ber., 32, 2564; Harries and Roeder, Ber., 
32, 3357; methyl hexanone prepared from (3 -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., SlJt, 
168; Harries, Ber., 34, 300; Bouveault and Tetry, Bull. Soc. Chim., 
1901 [III], 25, 441. 

2 Wallach, Ann. Chem., 289, 337. 
'Wallach, Ann. Chem., 300, 259. 



246 THE TERPENES. 

alcohol and ethereal salt by distillation with steam, the lactone, 
C 10 H 16 O 2 , is precipitated; it boils at 125 to 127 (15 mm.). 
The acid, C 10 H 16 O 2 , 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 10 H 14 O 2 , which melts at 44 to 
45, and boils at 265 to 268. An oxy-acid, C 10 H 16 O 3 , is pro- 
duced on hydrolyzing the lactone with aqueous alkali ; it melts at 
95, and forms a silver salt. 

An oxy-lactone, C 10 H 16 O 3 , 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 9 H 16 O, is produced when the oxy-lactone, C 10 H 16 O 3 , 
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, n^ = 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 10 H 16 O. 

When methyl cyclohexanone, C 7 H 12 O, and acetone are con- 
densed by means of alcoholic sodium methylate, a ketone, 1 C 10 - 
H 16 O, 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 or^o-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 

iWallach, Ber., 29, 1595 and 2955; Ann. Chem., 300, 268. 



ISOPULEGOL, AND ISOPULEGONE. 247 

index, n^ = 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 10 H 14 O = 
CH-C 6 H 5 , 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 10 H 17 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, n^ = 1.4792. 
When treated with phosphoric anhydride, it yields a terpene, 
C 10 H ]6 , boiling at 173 to 1,75. 

Wallach 1 suggests the following formula for synthetical pulegone: 







/\ ^ CH ' 
H,C CH-CT 

H I L X CH S 
\ / 

CH 2 
Ortho-isopulegone. 

12. ISOPULEGOL, C 10 H 17 OH, and ISOPULEGONE, C 10 H 16 O. 

An alcohol, C 10 H 17 OH, corresponding with natural pulegone,. 
has not yet been obtained free from menthol by the reduction 
of pulegone. An alcohol, C 10 H,.OH, isopulegol, is, however, 
produced from citronellal, C 10 H 16 O, an aliphatic terpene alde- 
hyde. 

It results in the form of its acetate by heating citronellal with 
an equal weight of acetic anhydride in an autoclave at 180 to- 

1 Wallach, Ann. Chem., SOO, 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 1 ). 

According to Barbier, 2 when citronellal is agitated with ten 
parts of five per cent, sulphuric acid for twelve hours, isopulegol 
is formed, together with menthoglycol, C 10 H 18 (OH) 2 ; the latter 
compound is also obtained from isopulegol. 

According to Tiemann, 3 commercial citronellal contains some 
isopulegol, together with other compounds ; its presence in the 
mixture may be recognized by its conversion into isopulegone 
upon oxidation. 

PROPERTIES. Isopulegol has an odor like menthol, boils at 
91 under a pressure of 13 mm., and has the rotatory power, 
[]/> = 2.65. Its specific gravity is 0.9154 at 17.5, the re- 
fractive index, n^ = 1.47292, and the molecular refraction, M = 
47.20. 

Menthoglycol 2 (menthandiol-3, 8), C 10 H 18 (OH) 2 , is a compound 
closely related to isopulegol. It is formea, together with some 
isopulegol and a compound, C 20 H 34 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 10 H 18 C1-O-COCH S , boiling at 124 to 
125 (10 mm.). This glycol may also be obtained directly from 
isopulegol. 

Isopulegone, C 10 H 16 O, is formed by the oxidation of isopulegol 
with an acetic acid solution of chromic anhydride ; 4 the product 
seems to consist of a mixture of two stereo-isomeric modifications, 
which are designated as a- and /5-isopulegone. 5 

According to Tiemann, the mixture of a- and /9-isopulegone, 
obtained by the oxidation of isopulegol, boils at 90 (12 
mm.), has the specific gravity 0.9213, the index of refraction, 
n^, = 1 .4690, the molecular refraction, M = 45.98, and the specific 
rotatory power, []^= -f 10 15', in a one decimeter tube. On 
treating with boiling dilute sulphuric acid and alcohol or with 

1 Tiemann and Schmidt, Ber., 29, 903. 

2 Barbier and Leser, Compt. rend., 12%, 1308. 

Tiemann, Ber., 82, 825. 

'Tiemann and Schmidt, Ber., 29, 903; SO, 22; Tiemann, Ber., 82, 825. 

5 Harries and Roeder, Ber., 32, 3357. 



/?-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 2 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, [a]^= 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 10 H 16 NOH, is formed, together with the ft- 
derivative, by the action of hydroxylamine on isopulegone. It 
melts at 120 to 121, and is volatile with steam. 

/3-Isopulegonoxime, C 10 H 16 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 ^-oximes. 

a-Isopulegone semicarbazone, C 10 H 16 = N-NH-CO-NH 2 , 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. 

^-Isopulegone semicarbazone, C 10 H 16 = N NH CO NH 2 , melts 
at 183 (Harries). According to Tiemann, it melts at 180, and 
is sparingly soluble in ether. 

A mixture of the a- and /9-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 /3-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 




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, 


99tol01(12mm.) 


90 (12mm.). 


94 to 95 (14mm.). 


Acid sodium sul- 
phite, 


forms a crystalline 
derivative. 


does not yield a 
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 (14mm.). 


yields isopulegol, 
b. p. 91 (13 mm.) 


yields synthetical 
pulegol, b. p. 103 
to 104 (15 mm.). 


Oximes, 


normal oxime, C 10 - 
H 16 NOH, m. p. 
118 to 119. 
pulegone hydroxy- 
lamine, C ]0 H, 9 - 
NO 2 , m. p. 157. 


a-derivative, C 10 H 16 - 
NOH, m. p. 121. 
/3-derivative, C 10 Hj 6 - 
NOH, m. p. 143. 
mixture (?), m. p. 
134. 


liquid, b. p. 145 
(15 mm.). 


Semicarbazones, 


m. p. 172. 


a-derivative, m. p. 
171 to 172. 
/3-derivative, m. p. 
180 
mixture (a- and/?-), 
m. p. 173 to 174. 


exists in two modifi- 
cations ; m. p. 70 
to 85, and 144. 



13. MENTHENONE, C 10 H 16 O. 

A ketone, C 10 H 16 O, was obtained by Urban and Kremers 1 by 
boiling nitrosomenthene (m. p. 65 to 67) with dilute hydro- 
chloric acid (1 : 1), and in the year 1899 Wallach 2 gave it the 
name menthenone. 

1 Urban and Kremers, Amer. Chem. Journ., 16, 401. 
2 Wallach, Ann. Chem., 305, 272. 



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 1 ). 

According to Wallach, menthenone boils at 95 to 97 under 
12 mm. pressure, has the refractive index, n^, = 1.4733, at 20, 
the molecular refraction, M = 46.42, and the specific gravity 
0.919 at 20. 

Menthenone hydrogen sulphide, 1 C 10 H 16 O 2H 2 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 10 H 15 O NO, is prepared according to 
Baeyer's method for the preparation of bisnitrosopulegone ; it 
melts at 115 to 115.5. 

Menthenone phenylhydrazone, C 10 H 16 = N NHC g H 5 , 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 10 H 17 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 10 H 12 O ( = CH-C 6 H 5 ) 2 , 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 zinc dust and glacial acetic acid it 
gives rise to the corresponding alcohol, C 24 H 26 O, which forms 
colorless crystals, and melts at 72 to 75 (Wallach). 

14. ISOCAMPHOR, C 10 H 16 O. 

When camphoroxime, in glacial acetic acid solution, is 
treated with nitrous acid (sodium nitrite), it yields a compound, 
C 10 H 16 N 2 O 2 , which Angeli and Rimini 2 call pernitrosocamphor 
and which Tiemann 3 terms camphenylnitramine ; it melts at 43. 
Pernitrosocamphor is attacked by cold concentrated sulphuric 
acid with evolution of nitric oxide and formation of a ketone, 

1 Richtmann and Kremers, Amer. Chem. Journ., 18, 771. 
*Angeli and Rimini, Ber., 28, 1077 and 1127; Gazz. China., 26 [II], 29, 
34, 45, 228, 502 and 517; 28 [I], 11. 
s Tiemann, Ber., 28, 1079; 29, 2807. 



252 THE TERPENES. 

C 10 H 16 O, isocamphor. This ketone should possibly be classified 
with the ketodihydrocymenes. 

Isocamphor is also formed by treating isopernitrosofenchone, 
C 10 H 16 N 2 O 2 , with concentrated sulphuric acid. 

Isocamphor 1 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, 1 C 10 H 16 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 10 H 16 = N-NH CO NH 2 , melts at 
215. 

Isocamphor bisnitrosochloride, (C 10 H 16 O) 2 (NOC1) 2 , 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. 

Tetrab.ydroisocam.phor, 1 C 10 H 19 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- 
ylur ethane, which forms colorless crystals and melts at 155. 

Dihydroisocamphor, C 10 H 18 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 10 H U O = 
CH'C 6 H 5 , is formed ; it crystallizes from alcohol in small, white 
needles, melting at 217. The formation of this compound indi- 
cates that dihydroisocamphor contains the group CO CH 2 . 

When isocamphor is oxidized with an alkaline solution of 
potassium permanganate, it yields a-isopropyl glutaric acid, 
C 8 H 14 O 4 , which crystallizes in white needles and melts at 96 ; it 
has been synthetically prepared by W. H. Perkin. 3 It forms an 

Compare M. Spica, Gaz. Chim. Ital., 31 [II], 286. 

* Rimini, Gazzetta (1900), SO, 59<J. 

3 W. H. Perkin, jun., Journ. Chem. Soc., 69, 1495. 



J 6 -MENTHENE-2-ONE. 253 

anhydride, C 8 H 12 O 3 , which crystallizes in long needles, and melts 
at 60. It is converted into suctinic add by oxidation with 
chromic acid, and also gives rise to an anilide, melting at 160. 

It may further be mentioned that a ketone, 1 C 10 H 16 O, isomeric 
with camphor, is formed by the dry distillation of 3-methyl-Q-iso- 
propyl-dP-cyclohexenone carboxylic add, C 10 H 15 OCOOH ; it is an 
oil, having a camphor-like odor, and boils at 217 to 219. Its 
oxime forms beautiful, monoclinic crystals. 

/?-Isocamphor, C 10 H 15 OH, is an unsaturated alcohol which 
Duden 2 obtained by the action of nitrous acid on camphenamine, 
C 10 H I5 NH 2 ; it sublimes in long needles having the odor and 
appearance of camphor, and melts at 102. It has the specific 
rotatory power, [a] = -f 17.65, in methyl alcohol. Its phenyl- 
urethane crystallizes from petroleum in long needles and melts at 
112. 

15. PINOLONE, C 10 H 16 O, and PINOLOL, C 10 H 17 OH. 

Wallach 3 obtained the ketone, pinolone, by treating isopinole 
dibromide, C 10 H 16 OBr 2 , 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, n^ = 1.46603, at 20. 

Pinolonoxime, C 10 H 16 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 10 H 16 = N-NH-CO-NH 2 , melts at 158. 

Pinolol, C 10 H 17 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, n^ = 1.47292, at 20. 

16. J 6 -MENTHENE-2-ONE, C 10 H 16 O. 

According to Harries, 4 when hydrobromocarvone is reduced in 
methyl alcoholic solution with zinc dust, about one-quarter of the 
product consists of carvone and the remainder is a ketone, C 10 H 16 O, 
called J 6 -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] I) = -f 49.5, in 
a 10 cm. tube. 

1 J. A. Callenbach, Ber., SO, 639. 

2 Duden and Macintyro, Ann. Chem., 813, 59. 

a Wallach, Ann. Chem., 306, 275; 281, 154; Ber., 28, 2710. 

* Harries, 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 10 H 16 O H 2 S, crystallizes 
in lustrous needles and melts at 222 to 225. 

The oxaminoxime, C 10 H 16 (NOH)(NH 2 OH), 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 by a current 
of air, it gives rise to a dioxime, C, H 16 (NOH) 2 , which crystallizes in 
colorless prisms and melts with decomposition at 194 to 196. 

When 2/ 6 -menthene-2-one is reduced with zinc dust and alco- 
holic sodium hydroxide, it yields dextro-carvomenthone. When re- 
duced with aluminium amalgam, it gives a dimolecular compound, 
C 20 H 34 O 2 ; the latter yields a phenylhydrazone, melting at 260. 

The ketone unites slowly with hydrobromic acid, forming a 
yellow oil. 

17. TERPINEOL, C 10 H 17 OH. 

The name terpineol was formerly used to designate a substance 
which to-day is recognized as a mixture of isomeric alcohols, 
C 10 H 17 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 : 

QujHie < j C 10 H 1T OH < m C 10 H 18 (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, 2 " 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 ajlowed to stand for twelve hours. 

Tilden 3 first obtained " terpineol " from terpine hydrate, and 
Wallach 4 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 

1 Deville, Ann. Chem., 71, 351. 

2 Flawitzky, Ber., 12, 2354. 

'Tilden, Journ. Chem. Soc., 1878, 247; 1879, 287; Ber., 12, 848; Jahreab. 
Chem., 1878, 1132. 

<Wallach, 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 l 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," 2 although for some time it was impossible to isolate 
the solid compound from the liquid product. 

If terpine be given the formula : 




H 3 C CH 3 , 
Terpine. 



it will be seen that three isomeric, unsaturated alcohols, C 10 H 17 OH, 
may be derived from it, thus : 





H S C CH S 

A 3 -Terpen-l-ol. 




H 3 C CH 3 

A*< 8 >-Terpen-l-ol. 



'Bouchardat 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 TEEPENES. 

By totally different methods, Wallach and Baeyer came to the 
same conclusion, that solid terpineol (m. p. 35) should be 
considered as a J^terpen-^ol, expressed by formula la. This 
formula, however, is hardly conformable to the results of experi- 
ments which have more recently been published by Wallach, 1 and 
by Tiemann and Semmler ; 2 according to their researches it ap- 
pears possible, and even probable, that terpine should be repre- 
sented by the formula : 




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 : 





A 8 < 9 >-Terpen-l-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 la. This formula was first proposed 
by G. Wagner. 3 

'Wallach, Ber., 28, 1773. 

2 Tiemann and Semmler, Ber., 28, 1778. 

G. Wagner, Ber., 27, 1652. 



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 J 4(8) -terpen-l-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. 1 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, 2 
erigeron, kesso, 3 kuromoji, 4 and marjoram 5 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. 6 

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). 

1 Schimmel & Co., Semi-Annual Report, April and May, 1901, 75. 

2 Weber, Ann. Chem., 238, 98. 

3 Bertram and Gildemeister, Arch. Pharm., 228, 483. 
<Kwasnick, Ber., 24, 81. 

sBiltz, Ber., 32, 995. 

6 Schimmel & Co., Semi-Annual Report, Oct., 1897, 11. 

17 



258 THE TERRENES. 



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 alcohol 
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 1 ). 

It is worthy of notice that inactive, solid terpineol occurs in 
the form of its acetate in cajuput oil (Voiry 2 ). The chemists of 
Schimmel & Co. 3 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 4 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 "tei*pineol" identical with 
that formed from pinene (Stephan 5 ). 

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, n^ = 1.48132 at 20 (Schimmel & Co. 3 ). 

According to Tiemann and Schmidt, 6 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 7 ; 

1 Bouchardat and Lafont, Compt. rend., 102, 1555. 

2 Voiry, Compt. rend., 106, 1538. 

3 Schimmel & Co., Semi-Annual Report, April and May, 1901, 76. 

4 Kremers, Pharm. Rundschau, 13, 137. 

S K. Stephan, Journ. pr. Chem., 60 [II], 244. 

6 Tiemann and Schmidt, Ber., 28, 1781. 

7 Wallach and Kerkhoff, Ann. Chem., 275, 103. 



TERPINYL METHYL ETHER. 259 

their researches were carried out in the same direction as previous 
investigations of Wallach l 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 2 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, 3 C 10 H 17 O'COCH 3 , 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, 

<$ 

\>C, 



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 4 ). 

Wallach 1 had previously obtained this urethane from liquid 
" terpineol." 

Terpinyl methyl ether, C 10 H 17 OCH 3 , 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 

i Wallach, Ann. Chem., 230, 268; 239, 20. 
'Wallach, Ann. Chem., 291, 342. 

aSchimmel & Co., Semi-Annual Report, Oct., 1897, 64. 
* Wallach 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 x ). It combines with hydriodic acid in a glacial 
acetic acid solution to form a hydriodide, which yields the methyl 
ether of tertiary menthol by reduction with acetic acid and zinc 
dust. 




Tertiary menthyl methyl ether. 



Terpineol dibromide, C 10 H, 7 OH Br 2 , 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 10 H 17 O'OH, is formed, together with a small quantity of pinole; 
large quantities of pinole, C 10 H 16 O, are obtained, together with a 
small amount of cymene, when terpineol dibromide is heated 
with sodium alcoholate (Wallach 2 ). 

Baeyer 3 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, , 8 (?})-tri- 
bromoterpane, C 10 H 17 Br 3 , is produced ; this is a liquid, which, on 
bromination in an acetic acid solution, is converted into dipentene 
tetrabromide. 

According to Wallach, 4 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, 

i Baeyer, Ber., 26; 2560 ; 26, 826. 
* Wallach, Ann. Chem., 277, 113. 
s Baeyer, Ber., 27, 440. 
'Wallach, Ann. Chem., 281, 140. 



TEEPINEOL XITROSOCHLOEIDE. 



261 



C 10 H 14 BrOCH 3 , which is obtained by treating limonene tetra- 
bromide with sodium methylate. Carveol methyl ether yields in- 
active carvone by oxidation with chromic anhydride. 

The following formulas illustrate the transformation of solid 
terpineol into carvone : 





Terpineol (A'-terpen-4-ol ). 



3^7 

Terpineol dibromide. 



H(OCH 3 ) 




1,[2, 4-Tribromoterpane. 




Carveol methyl ether. 



The development of those formulas which indicate that terpineol 
should be regarded as a J^terpen-S-ol is given on page 198. 

Terpineol nitrosochloride, C 10 H 17 (OH) NOC1, 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 cc. 
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 1 ). 

It is a comparatively stable compound and may be recrystal- 
lized from methyl alcohol or ethyl acetate, melting at 102 to 103. 

J Wallach, Ann. Chem., 277, 121. 



262 THE TERPENES. 

When hydrogen chloride is eliminated from terpineol nitroso- 
chloride, oxydihydrocarvoxime, 1 C 10 H 15 (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 
^-position (Wallach 2 ). 

Terpineol nitrosate, C 10 H 17 (OH) N 2 O 4 , was prepared by Wal- 
lach, 3 but has not been carefully studied. 

Terpineol nitrolpiperidide, 4 C 10 H, 7 (OH) NO NC 5 H 10 , is prepared 
by the interaction of the nitrosochloride with piperidine. It crys- 
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 10 H 17 (OH) NO NHC 6 H 5 , 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 10 H 20 O 3 , which 
must be regarded as methyl isopropyl trioxyhexahydrobenzene, 
or, according to Baeyer, trioxyterpane. By further action of per- 
manganate, trioxyterpane loses four atoms of hydrogen, and forms 
the keto-lactone, C 10 H 16 O 3 , 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 8 ). 

Trioxyhexahydrocymene [1,2, 8 -trioxyterpane or 1, 2, 8-trioxy- 
menthane] , C 10 H 20 O 3 . 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 

JWallach, Ann. Chem., 291, 342. 
"Wallach, Ber., 28, 1773. 
Wallach, Ann. Chem., 277,. 121. 
*Wallach, Ann. Chem., 281, 140. 
s Wallach, Ann. Chem., 27,5, 150. 



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 1 ), 

CioH 2 oO 3 3H 2 O = C 10 H U . 

Under suitable conditions it may part with but two molecules 
of water, yielding carvenone, C 10 H 16 O : 

CioH 2 oO 3 2H 2 O = C 10 H 16 O. 

According to Ginzberg, 1 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 10 H 16 (OH) 2 , 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 10 H 20 O 4 , which is 
isomeric with limonetriol, and melts at 168.5 to 169.5. The 
glycol is regarded as a A^^-menthene-l : 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 2 ). 

Keto-lactone, 3 C 10 H 16 O 3 , is quantitatively formed by oxidizing 
trioxyterpane, C 10 H 20 O 3 , 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. 

1 Wallach, Ann. Chem., 277, 110 and 122. 

2 A. Ginzberg, Ber., 29, 1198. 

Wallach, 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 cc. 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 
crystallization ; 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 10 H 16 O 3 , 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 1() H 18 O 4 , by the 
action of potassium hydroxide ; therefore, Wallach 1 assumes that 
it is a keto-lactone. Wallach 2 further determined that it is readily 
converted into acetic acid and terpeuylic acid by oxidation with 
permanganate. 

Tiemann and Semmler 3 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 l -eihyl-3-heptanon-6- 
olide-1-3 1 . Tiemann and Schmidt 4 confirmed these results ; they 
also showed that the keto-lactone, C 10 H 16 O 3 , is formed, together 
with terpenylic acid, by the oxidation of terpineol and of trioxy- 
ihexahydrocymene with a mixture of chromic and glacial acetic 
acids. 

According to Mahla and Tiemann, 5 oxidation with chromic and 
sulphuric acids converts methoethylheptanonolide (keto-lactone) 
into terpenylic acid, 6 C 8 H 12 O 4 , while oxidation with nitric acid 
gives rise to terebic acid, C 7 H 10 O 4 . 

According to Tiemann, 7 the keto-lactone melts at 64, and its 
oxime, C 10 H 16 O 2 (NOH) (see above), crystallizes in rhombs, and 

Wallach, Ber., 28, 1773. 

2 Wallach, Ann. Chem., 277, 118. 

sTiemann and Semmler, Ber., 28, 1778. 

* Tiemann and R. Schmidt, Ber., 28, 1781. 

sMahla and Tiemann, Ber., 29, 2621. 

sMahla and Tiemann, Ber., 29, 928. 

T Tiemann, Ber., 29, 2616. 



KETO-LACTOXE. 



265 



melts at 79 to 80; when heated with concentrated sulphuric 
acid at 100, the oxime is converted into acetic acid and a base, 
mdhyl--aminoethyl-3- j pentolide, C g H 13 O 2 NH 2 . 

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 J and supported by Schry ver, 2 
we may formulate the oxidation of terpineol in the following 
manner : 





OOH 



H 3 C CH 3 
Intermediary product. 




\> 

H S C CH, 
Terpenylic acid. 



Trioxyhexahydrocymene. 
H 



H 2 (J COO 
H '\/ H > 



H 



H 3 C CH S 

Keto-lactone, C 10 H 16 O 3 

(Methyl-^-ethyl-S- 
heptanon-G-olide-1-3 1 ). 



1 Wallach, Ann. Chem., 259, 322. 
*Schryver, Journ. Chem. Soc., 1893, 1327. 



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. 1 

Semmler 2 obtained an active terpineol, C 10 H 17 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 3 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, [] 1) = 
-f 88. 

The fraction boiling at 150 to 164 at 14 mm. pressure of 
Ceylon cardamom oil contains a terpineol, 4 melting at 35 to 37; 
it is dextrorotatory, [a]^ = 8331', at 21. It yields a terpinyl 
phenylur ethane, melting at 112 to 113, which is optically ac- 
tive, \OL\D = + 3358', 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 5 ; it 
boils at 217 to 218, melts at 35, and is dextrorotatory, 
[a] D = + 7918', at 22. It yields a terpinyl phenylurethane 
(m. p. 112), and a nitrolpiperidide (m. p. 151). 

Godlewsky 6 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] /) = 9528', in an alcoholic solution. Oxidation with a 
one per cent, solution of permanganate converts it into trioxymen- 
thane (menthanetriol or trioxyhexahydrocymene'), C 10 H 20 O 3 ; when 
this compound is oxidized with chromic acid, the keto-lactone 
(methoethylheptanonolide), C 10 H ]6 O 3 , is formed, which' differs by its 
optical activity, [#]/> = + 55.3 , in alcoholic solution, and a con- 
siderably lower melting point (45 to 46), from the keto-lactoue, 

'For optically active terpineol prepared by action of alcohol and nitrous 
acid on dextro- or levo-pinene, see P. Genvresse, Compt. rend., 132, 637. 
* Semmler, Ber., 28, 2189. 

3 Bouchardat and Tardy, Compt. rend., 121, 1417. 
*Schimmel & Co., Semi- Annual Report, Oct., 1897, 11. 
sSchimmel & Co., Semi-Annual Report, April, 1897, 27. 
sj. Godlewsky, J. Russ. Chem. Soc., 31, 203; Chem. Centr., .7899 [I], 1241. 



OPTICALLY ACTIVE TERPINEOLS. 267 

C 10 H 16 O 3 , 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 10 H 16 O 3 , melting at 48 to 49 \ which Baeyer 1 obtained from 
levorotatory trioxyterpane (m. p. 97 to 98), prepared indirectly 
from optically active 1 : 8-oxybromotetrahydrocarvone, C 10 H 16 BrO- 
(OH). 

In the oxidation of the above-mentioned levo-terpineol, optic- 
ally active terpenylic acid is also produced. 

According to Stephan, 2 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 1-linalool into d-terpineol, and d-lina- 
lool into 1-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. 3 

According to Biltz, 4 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 10 H 20 O 3 , and the keto-lactone, C 10 H 16 O 3 . 

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. 

iBaeyer and Baumgaertel, Ber., 31, 3208. 
2K. Stephan, Journ. pr. Chem., 58 [II], 109. 

3 Ertschikowsky, Journ. d. russ. phys.-chem. Ges., 28, 132; Abs. Bull. Soc. 
Chim., 16 [III], 1584. 
*W. Biltz, Ber., 32, 995. 



268 



THE TERPENES. 



O> h-i 

a Pi 



M 
W 

ft 

W 
fe 
W 
f* 


EH 




n 





iC 

CO 

PL! 




lo. Jo 15 



KcJ 



A 




ISOMERIC TERPINEOL. 269 

18. ISOMEEIO TERPINEOL, C 10 H 17 OH, MELTING AT 69 TO 
70. (J 4 < 8) -TERPEN-1-OL.) 

When the tribromoterpane (m. p. 110), which Wallach ob- 
tained by brominating dipentene dihydrobromide, is reduced with 
zinc dust and acetic acid, it yields the acetate of an isomeric ter- 
penol (terpineol) ; this is converted, on hydrolysis, into a crystal- 
line alcohol, melting at 69 to 70, which is to be regarded as 
a J 4(8) -terpen-l-ol (Baeyer 1 ). 

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 (a portion of the acetic acid 
solidifies at this temperature) and is treated carefully and with 
constant shaking with thirty grams of zinc 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. 

J 4(8) -Terpen-l-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, 2 J 4(8) -terpen-l-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 J 4(8) -terpen-l-ol 
acetate may be readily obtained. 

Liquid " terpineol " prepared by Schimmel & Co. does not 
contain J 4(8) -terpen-l-ol. 

When terpenol acetate is dropped into boiling quinoline, ter- 
pinolene distills over. 2 

J 4(8) -Terpen-l-ol and its acetate readily give dipentene dihydro- 
bromide when treated with a glacial acetic acid solution of hy- 
drogen bromide. 

i Baeyer, Ber., 21, 443. 
2 Baeyer, Ber., 27, 815. 



270 THE TERPENES. 

Terpenol dibromide, 1 C 1() H 17 OH-Br 2 (4, 8-dibromoterpen-l-ol), 
results by the addition of the theoretical quantity of bromine to 
the alcoholic ethereal solution of terpeuol ; it crystallizes in long 
needles and melts at 114 to 115. 

Terpenol acetate dibromide, 1 C 10 H 17 (OCOCH 3 )-Br 2 , 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 J 4 W-terpen-l-ol acetate, C 10 H 17 (OCOCH 3 > 
NOC1. This very characteristic compound is prepared according 
to the directions given by Thiele 2 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 1 ). 

J 4(8) -Terpen-l-ol also gives a blue nitrosochloride, but it has 
not been thoroughly examined. 

Nitrosobromide of J 4 W-terpenol acetate, C 10 H 17 (OCOCH 3 )-NOBr, 
crystallizes in blue needles, and melts at 81 to 82. According 
to Baeyer and Blau, 3 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 hydrobromic acid salt of a 
base results, which contains a hydroxylamine group. The con- 
stitution of this salt is expressed by the empirical formula, 
C 10 H 17 Br 2 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 10 H 16 Br NHOH, is formed. It melts at 100 to 102. 
Nitrous acid changes it into a nitroso-compound, melting at 138 
to 139. 

i Baeyer, Ber., 27, 443. 
* Thiele, Ber., 27, 455. 
Baeyer and Blan, Ber., 28, 2289. 



ISOMERIC TERPINEOL. 271 

It is mentioned on page 93 that when l-bromo-J 4(8) -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- 
J 4(8) -terpene and of J 4(8) -terpenol acetate yield the same product, 
C 10 H ir Br 2 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 3 C CH 3 

A*(8>-Terpen-l-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- 



272 



THE TERPENES. 



terpane (m. p. 110). The following formulas illustrate these re 
lations : 



)H 
H,<J CH 2 

H,C CH, 




A<(8)-Terpen-l-ol. 




H 2 

Br 
CH 
H 3 C CH 3 
Dipentene dihydrobromide. 




1, 4, 8-Tribromoterpane. 
(m. p. 110). 




H 3 C CH 3 

Terpinolene. 



H 2 c CH 

HC CH 



CBr 
H 3 C CH, 

Terpinolene di- 
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 
1, 4, 8-trioxyterpane, C 10 H 20 O 3 , is obtained, when J 4(8) -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 1 ). 

19. ISOMERIC TERPINEOL, C 10 H 17 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, 2 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 long 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, n^ = 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. 

Baeyer and Blau, Ber., 28, 2289. * 

2 Schimmel & Co., Semi- Annual Report, April-May, 1901, 75. 

18 



274 THE TERPENES. 

The phenylur ethane, C^H^C^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 nitrosochlor ide, C 10 H 17 OH NOC1, 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 9 H 16 O 2 . 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 9 H lt .O 2 , is formed ; under 
similar conditions terpineol, m. p. 35, gives rise to the keto-lac- 
tone, C 10 H 16 O 3 . This oxy-ketone boils at 140 to 145 under 
19 mm. pressure, has the sp. gr. 1.023 at 20 and the refractive 
index, n^ = 1.47548, at 20. Its semimrbazone 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 g H 14 O 3 ; 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 : 




H 3 C CH 2 

A80)-Terpen-l-ol. 

20. PINOLE, C 10 H 16 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, 1 and named pinole. 

iWallach 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 l 
showed that pinole is produced when the crystalline compound, 
C 10 H 18 O 2 , obtained by Sobrero 2 by exposing oil of turpentine to 
the action of moist oxygen in the sunlight, is distilled with dilute 
sulphuric acid. In the meantime, Wallach 3 prepared pinole 
hydrate, 

H 



by the addition of the elements of water to pinole, and proved 
the identity of this hydrate with the crystalline substance, 
C 10 H 18 O 2 , which was first observed by Sobrero. 

Pinole may also be regenerated from pinole dibromide, 
C 10 H 16 O Br 2 , by boiling with alcoholic potash, 4 or by heating a 
benzene solution of the dibromide with sodium wire. 3 Accord- 
ing to Wallach, 5 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 5 ). 

i Armstrong, Chem. Ztg., 1890, 838; Journ. Chem. Soc., 1891, I., 311; 
Ber., 2Jt, 763, Ref . ; Armstrong and Pope, Journ. Chem. Soc., 1891, I., 315; 
Ber., 24, 764c. 

"Sobrero, Ann. Chem., 80, 108. 

aWallach, Ann. Chem., 259, 309. 

* Wallach and Otto, Ann. Chem., 253, 249. 

s Wallach, 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 . 1 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 : 

Ci H 16 O H 2 O = C 10 Hi 4 . 

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 

It has been mentioned that this compound was obtained by So- 
brero 2 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 a crystalline product after evaporation of the ether,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 3 ). 

According to Wagner, 4 pinole hydrate is to be regarded as a 
cis-compound. 

1 Wallach, Ann. Chem., 281, 148. 
*Sobrero, Ann. Chem., 80, 108. 
"Wallach, Ann. Chem., 259, 313. 
* Wagner 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 1 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 recry stall ized unchanged from boiling acetic anhydride ; 
on the other hand, Ginzberg 3 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, 2 pinole hydrate is to be classified as an 
unsaturated f-glycol ; this view is in harmony with the fact that, 
when oxidized with potassium permanganate, it yields a tetra- 
hydric alcohol, cis-trans-sobrery trite (menthane-1, 2, 6, 8-tetrot)* 
C lo H. 20 O i . Accordingly, pinole hydrate (sobrerol) is termed J 6 - 
menthene-2, 8-diol, or J l -menthene-6, 8-diol. 3 

Cis-trans-sobrerytrite, C 10 H 20 O 4 , is very hygroscopic, and readily 
forms the hydrate, C, H 20 O 4 -f 2H 2 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 4 obtained oxydihydrocarvone, C 10 H 15 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 1 obtained terpenylic acid, oxalic acid and carbon 
dioxide. 

Cis-pinole hydrate dibromide 4 (1, 6, 2, 8 dibromodioxyhexahy- 
drocymene), C 10 H 16 Br 2 (OH) 2 , is formed by the addition of a solu- 
tion of bromine in chloroform to a solution of pinole hydrate in 

' Wallach, Ann. Chem., 259, 313. 

2 Wagner, Ber., 27, 1648; Ber., 32, 2069. 

sGinzberg, Ber., 29, 1195. 

'Wallach, 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 10 H 162' 

Cis-pinole dibromide, 1 C IO H 16 O-Br 2 , 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 2 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. 3 A far more important 
result was obtained by Wallach 3 by the reduction of the 
dibromide with zinc dust and glacial acetic acid in the cold ; 
under these conditions, crystalline terpiueol (m. p. 35) is 
formed. 

Hydrobromopinole dibromide, C 10 H 17 OBr 3 . According to Wal- 
lach, 2 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. 

1 Wallach and Otto, Ann. Chem., 253, 253. 
'Wallach, Ann. Chem., 268, 224. 
3 Wallach, Ann. Chem., 28 1, 148. 



CIS-TRANS-PINOLE GLYCOL,. 279 

On reduction, the tribromide yields an unsaturated ketone, pino- 
lone, C 10 H 16 O, which has an odor resembling that of amyl acetate 
(Wallach l ). When a solution of this tribromide in glacial acetic 
acid is digested with silver acetate , a compound, C 12 H 20 Br 2 O 3 , 
is obtained; it crystallizes from methyl alcohol, and melts at 
118 to 120 (Wallach 1 ). 

Isopinole dibromide, 2 C 10 H 16 O-Br 2 , 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 uusaturated 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 10 H 16 O Br 4 , which melts at 132. 

On reducing isopinole dibromide with zinc and glacial acetic 
acid, the ketone, pinolone, C 10 H 16 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 IO H 16 O(OH) 2 , 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 Friistuck 3 ). 

It may also be obtained by the hydrolysis of c?s-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 1() H 16 O(OH) 2 . According to Wagner, 4 
pinole is oxidized by a very dilute solution of potassium perman- 
ganate to a glycol, isomeric with that obtained from pinole dibro- 

i Wallach, Ber., 28, 2708. 

*Wallach, Ann. Chem., 306, 267. 

Wallach and Frustiick, Ann. Chem., 268, 223. 

* Wagner, Ber., 27, 1644; Wagner and Slawinski, Ber., 32, 2067. 



280 THE TEKPENES. 

raide. It appears to be a dimorphous compound, crystallizing 
from ether and ethyl 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 inm.) ; after standing during a long time (Wagner 
reports two years), it solidifies, and melts at 37 to 38. (Com- 
pare with Wallach. 1 ) 

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-frans-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 10 H Tfi O(OCOCH 3 ) 2 , is produced by 
the treatment of pinole dibromide with silver or lead acetate 
(Wallach 2 ). 

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. 3 

Cis-pinole glycol dipropionate, 2 C 10 H 16 O(OCOC 2 H 5 ) 2 , 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, 4 C 10 H 16 O (OC 2 H 5 ) 2 , 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 5 (cis-pinole oxide), C 10 H 16 O 2 , is 
produced by the action of sodium methylate on the dibromide of 

i Wallach, Ber., 28, 2708. 

zWallach, Ann. Chem., 259, 311; 268, 222. 

aWallach, Ann. Chem., 281, 149. 

* Wallach and Otto, Ann. Chem., 253, 260. 

s Wallach and Guericke, Ann. Chem., 291, 342. 



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, njr, = 1.4588, at 20. It is a 
saturated compound, and hydrolysis converts it into cz's-pinole 
glycol (m. p. 124) ; it is, therefore, a true anhydride of the latter 
compound. 

OtVpinole glycol anhydride is also described by Wagner l 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. 2 

Cis-pinole glycol- 1-chlorhydrin, 2 C 10 H 16 OC1(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 converts this chlorhydrin into a chloroketone, C 10 H 15 - 
C1O.J, 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 10 H 16 OC1(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] Z) = -f 88 23'; that obtained from dextro-pinene 
melts at the same temperature, but is levorotatory, [a] D = 
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 c?'s-pinole glycol (m. p. 
123 to 124). 

i Wagner and Slawinski, Ber., 32, 2065. 

2 A. 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 10 H ]8 O 3 . This compound melts 
at 73 to 74.5, is dextrorotatory, [] z > = +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-l, 2-dichlor-6, 8-diol, C 10 H 18 O 2 C1 2 , 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 monochloVhydrin (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 zinc dust and alcohol, 
it yields limonene (?) and pinole hydrate (m. p. 129 to 129.5). 

Cis-sobrerytrite (menthane-1, 2, 6, 8-tetrol), C 10 H 20 O 4 , 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 m-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-derivaiive easily forms a hydrate, 
C 10 H 20 O 4 -f 2H 2 O, while the cis-modification does not. 

Nopinole glycol, C 10 H I8 O 3 , a product of the action of hypochlo- 
rous acid on piuene, 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 ISOXITROSOCHLORIDE. 283 

oil. Oxidation converts it into formic acid and a non-volatile, 
syrupy acid, no acetic or terpenylic acid being produced. 

Pinole bisnitrosochloride, 1 (C 10 H 16 O) 2 N 2 O 2 C1 2 , is formed when six 
cc. 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 cc. 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 10 H 16 NOC1, which dissolves in chloro- 
form forming a blue colored solution. The same 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, 2 C 10 H 16 O NOC1, is produced, as above 
mentioned, by the slow spontaneous change of the dimolecular 
compound. 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, /9-naphthylamine, etc.), forming nitrolamines which are 
identical with those obtained from pinole bisnitrosochloride (see 
below). 

i Wallach and Otto, Ann. Chem., 253, 260; Wallach and Sieverts, Ann. 
Chem., 306, 278. 

2 Wallach 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 , 



x 
Cl H <OCH 3 

forms well defined crystals, and melts at 138. 
Ethoxyl-derivative, 



crystallizes in prisms, and melts at 100. 

Benzoyl chloride reacts with the pinole nitrosochlorides forming 
6enzoi//-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. 1 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 6is-nitrosochlorides are converted into 
nitrolamines, since, according to the observations so far reported, 
the nitrolamines are always monomolecular compounds (Wallach 2 ). 

Pinole nitrolamine, C 10 H 16 O NO-NH 2 , 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 10 H, 8 N 2 O 2 HC1, which crys- 
tallizes well from water or dilute alcohol. 

Pinole nitrolpiperidide, C 10 H 16 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. 

i Wallach and Otto, Ann. Chem., 253, 260. 
* Wallach and Sieverts, Ann. Chem., 306, 281. 



EUDESMOLE. 285 

The hydrochloric! e is precipitated from an ethereal solution of 
the base, and is very readily soluble in water. 

Pinole nitrolbenzylamine, C 10 H 16 O-NO NHCH 2 C 6 H 5 , 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 10 H 16 O NO NHC 6 H 5 , 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- /3-naphthylamide, C 10 H 16 O NO NHC 10 H r 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, 1 the first product of the oxidation of 
pinole with a one per cent, solution of potassium permanganate at 
about is cis-trans-p'mo\e 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 2 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 in H lfi O. 



10 16 



A compound, C 10 H 16 O, which apparently contains neither a 
hydroxyl- nor a ketone group, was discovered by Smith 3 in the 
oil of Eucalyptus piperita. Although a very complete investiga- 
tion of this compound has not yet been made, it seems probable 

1 Wagner, Ber., 27, 1645. 

2 Wallach and Otto, Ann. Chem., 253, 256; Wallach, Ann. Chem., 259, 
317; Ber., 28, 2708. 

3 Baker and Smith, Journ. and Proc. of the Royal Soc. of N. S. 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 Eucalyptus pip- 
erita, goniocalyx, camphora, smithii, macrorrhyncha, stricta and 
elceophora. 

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. It is an unsaturated compound. 

Eudesmole dibromide, C 10 H 16 O Br 2 , 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 in a crystalline condition. It 
melts at 55 to 56. 

Dinitroeudesmole, C 10 H 14 (NO 2 ) 2 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. 



C. SUBSTANCES WITHOUT AN ETHYLENE LINKAGE. 

(KETONES, C 10 H 18 0, ALCOHOLS, C 10 H 19 OH, AND 
C 10 H 18 (OH) 2 , OXIDES, C 10 H 18 0, etc.). 

1. TETRAHYDROCARVONE (CARVOMENTHONE), C 10 H 18 O. 
Tetrahydrocarvone has the constitutional formula : 




H 3 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. 1 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 10 H 19 OH. It should 
be mentioned here that tetrahydrocarveol may be obtained by three 
different methods : from solid terpineol (m. p. 35) (Wallach), from 
carvotanacetone (Semmler, Wallach), and from carvone (Baeyer). 

Terpineol. Thujone. Carvone. 

CiofrOH C 10 H 16 O C 10 H U O 



Trioxyhexahydrocymene, Carvotanacetone, Dihydrocarveol, 

C 10 H 16 O C 10 H 17 OH 



Carvenone, Dihydrocarveol acetate hydriodide, 

C 10 H 16 H C 10 H 17 (OCOCH 3 )HI 

*5^ I ^J&- 

Tetrahydrocarveol ( Carvomenthol ) , 
C 10 H 19 OH 



Tetrahyd rocarvone, 
C 10 H 18 0. 

i Wallach and Herbig, Ann. Chem., 287, 371. 

287 



288 THE TERPEXES. 

Only inactive tetrahydrocarvone can be prepared from terpi- 
neol and car votan acetone, but the method proposed by Baeyer by 
means of carvone renders possible the formation of optically ac- 
tive modifications. 1 

In order to prepare it, Baeyer 2 oxidizes tetrahydrocarveol with 
Beckmann's chromic acid mixture, whilst Wallach 3 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 4 
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, n /) = 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, 5 when tetrahydrocarvone is 
gently oxidized at 40 with potassium permanganate, 5-isopropyl- 
heptan 2-onic acid (m. p. 40) is formed : 

CH 3 CO CH 2 CH 2 CH CH 2 COOH. 



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, 6 
C 20 H 34 N 2 O 4 , 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 10 - 
H ]8 N 2 O 3 , and a chlorinated ketone, C 10 H J7 C1O ; the bisnitrosylic 
acid crystallizes in leaflets and melts at 82 ; its oxime is also 
formed in the same reaction and melts at 75 to 77. 

1 Baeyer, Ber., 28, 1586. 

2 Baeyer, Ber., 26, 822. 
sWallach, Ann. Chem., 277, 133. 
'Wallach, Ber., 28, 1955. 
6 Baeyer and Oehler, Ber., 29, 27. 
eBaeyer, Ber., 28, 1588; 29, 33. 



a-ISOTETRAHYDROCARVOXIME. 289 

When the chlorinated ketone, C 1() H 17 C1O, above mentioned, is 
treated with sodium acetate and acetic acid for the elimination of 
hydrochloric acid, a ketone, C 10 H 16 O, is produced, which is called 
terpenone. 

Terpenone, 1 C 10 H 16 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 
alcohol in prisms or needles containing water of crystallization, 
and melts at 222 to 223. 

According to Semmler, 2 when terpenone, C 10 H 16 O, is oxidized 
with potassium permanganate, it yields a liquid acid, C 9 H 16 O 4 , 
which on further oxidation forms isopropyl succinic acid (m. p. 
112). From its behavior towards oxidizing agents, Semmler 
regards terpenoue as the ^seudo-ketone corresponding to carvotan- 
acetone ; the latter is regarded as an or^o-ketone. 

Tetrahydrocarvoxime, C 10 H 18 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 add, C 10 H 21 O 2 N, 
which separates from water in small crystals, melting at 201 to 
202; nitrous acid converts it into decenoic add, C 10 H 18 O 2 , which 
boils at 257 to 260, has a sp. gr. 0.936, the refractive index, n^ = 
1.4554, at 20, and a molecular refraction, M = 49.21 (Wallach 3 ). 

tt-Isotetrahydrocarvoxime, C lft H 19 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, 

JBaeyer and Oehler, Ber., 29, 35. 
2 Semmler, Ber., 33, 2459. 
sWallach, 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 w-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 /3-isoxime by heating above its melting point (to 
about 100 to 110). 

/9-Isotetrahydrocarvoxime, C JO H 19 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. 

tVA.mido-2-hexahydrocymene(tetrahydrocarvylamine),C 10 H 19 NH 2 , 
is formed when tetrahydrocarvoxime is reduced with sodium and 
alcohol. 

-Semicarbazone l and /3-semicarbazone 2 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 3 ); according to Baeyer, 4 it melts at 
194 to 195. 

Oxymethylene tetrahydrocarvone, C 10 H ]6 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 4 ). 

Condensation-product of tetrahydrocarvone and benzaldehyde, 5 
C 24 H 2g O 2 . 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. 

i Wallach, Ann. Chem., 286, 107. 

"Wallach, Ber., 28, 1955. 

Wallach and Herbig, Ann. Chem., 287, 371. 

*Baeyer, Ber., 28, 1586. 

5 Wallach, Ann. Chem., 305, 266. 



TETRAHYDROCARVEOL. 



291 



It is formed according to the equation : 



C 10 H 18 + 2C 6 H 5 CHO = H 2 + C 24 H 28 O 2 . 

It does not unite with the elements of hydrogen chloride ; on 
reduction, it seems to combine with two atoms of hydrogen. 

1, 8-Oxybromotetrahydrocarvone, 1 C 10 H 16 Br(OH)O, is produced 
in the form of its sodium salt when Wallach's dihydrocarvone 
dibromide (1, 8-dibromotetrahydrocarvone), C 10 H 15 BrOHBr, 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 10 H 16 O 2 is formed by treating 
oxybromotetrahydrocarvone with methyl alcoholic potash, 

The ketone, C 10 H 18 O, described by Marsh and Hartridge 2 
under the name earvanone, is probably identical with tetrahydro- 
carvone. 

For the action of Caro's reagent upon tetrahydrocarvone, refer- 
ence must be made to the original publication. 3 

2. TETRAHYDROCARVEOL (CARVOMENTHOL), C 10 H 19 OH. 

Tetrahydrocarveol was first described by Baeyer, 4 and shortly 
afterward by Wallach. 5 Baeyer obtained it from dihydrocarveol, 
the alcohol 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 zinc 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. 6 

i Baeyer and Baumgartel, Ber., 31, 3208. 

2 Marsh and Hartridge, Journ. Chem. Soc., 73, 857. 

a Baeyer and Villiger, Ber., 32, 3625. 

* Baeyer, Ber., 26, 822. 

sWallach, Ann. Chem., 277, 130. 

6 Baeyer, Ber., 26, 2558. 



292 THE TERPENES. 

Wallacli's method of preparation of tetrahydrocarveol is more 
convenient. He employs carvenone, C 10 H 16 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 1 in the reduction of carvo- 
tanacetone, C 10 H 16 O, with alcohol and sodium is identical with 
tetrahydrocarveol. This compound, designated by Semmler as 
tetmhydrocarvotanacetone, boils at 219 to 220, has the sp. gr. 
0.9014, and refractive index, n^ = 1.4685. (Compare with Wal- 
lach. 2 ) 

Optically active tetrahydrocarveol is also formed in the reduc- 
tion of phellandrene nitrosite with sodium and alcohol 3 (see tetra- 
hydrocarvone). 

Wallach 4 prepares pure tetrahydrocarveol by reduction of pure 
tetrahydrocarvoue with sodium and alcohol ; it boils at 220, has 
the specific gravity of 0.900 and refractive power, n^, = 1.46246, 
at 23. 

The odor of tetrahydrocarveol is very similar to that of terpin- 
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 an hydride con verts it into tetrahydrocarvone. 

Carvomenthene, C 10 H 18 , 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 10 H 19 Br, ob- 
tained by the action of warm, concentrated hydrobromic acid on 
tetrahydrocarveol, is heated with quinoline (Baeyer, and Konda- 
kotf and Lutschinin). 

Tetrahydrocarvyl phenylurethane, C 10 H 19 OCONHC 6 H 5 , 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 

'Semmler, Ber., 27, 895. 

2 Wallach, Ber., 28, 1955. 

3 Wallach and Herbig, Ann. Chem., 287, 371. 

''Wallach, Ann. Chem., 277, 130; Kondakoff and Lutschinin, Journ. pr. 
Chem., 60 [II.], 257. 



TETRA HYDROEUCARVONE. 



293 



melts at 74 to 75. It dissolves very readily in alcohol and 
ether (Wallach 1 ). 

Tetrahydrocarvyl acetate (carvomenthyl acetate 2 ), C 10 H 19 OCO- 
CH 3 , 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, [^1]^= + 4 7'. 

Tetrahydrocarvyl chloride, 2 C 10 H 19 C1, is a colorless liquid hav- 
ing the odor of menthyl 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, n^, = 1.46534, 
at 21, and a molecular refraction, M = 50.48. 

Tetrahydrocarvyl bromide, 2 C 10 H 19 Br, is colorless, boils at 95 
to 99 (10 mm.), has a specific gravity 1.1870 at 21, a refrac- 
tive index, n^ = 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 10 H 22 O 3 , which crystallizes in 
slender needles, and melts at 101 to 102. 

"Carvanol," 3 C 10 H 20 O, a compound obtained by the reduction 
of " carvenol" C 10 H 16 O, is probably identical with tetrahydrocar- 
veol ; on oxidation " carvanol " is converted into " carvanone " 
(tetrahydrocarvone), C 10 H 18 O. 



3. 



C 10 H 18 0. 



TETRAHYDROEUCARVONE, 

When dihydroeucarvoxime hydriodide, C 10 H 16 NOH-HI, is re- 
duced with zinc dust and an alcoholic solution of hydrogen chloride 
at 0, it is converted into the ketone, tetrahydroeucarvone. 4 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 10 H ]g NOH. 



Its semicarbazone, C 1() H 1S = N-NH>CONH 2 , 
ethyl acetate in fine needles, melts at 191, 
soluble in ether and ethyl acetate. 



crystallizes from 
and is sparingly 



1 Wallach, Ann. Chem., 277, 130. 

*Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257. 
3 Marsh and Hartridge, Journ. Chem. Soc., 73, 857. 
<Baeyer and Villiger, Ber., 31, 2067. 



294 THE TERPEXES. 

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 10 H 18 O 3 ; this acid is purified by regenera- 
tion from its semicarbazone. It is a liquid acid, and is probably 
a methyl ketone. Its semicarbazone, C 10 H 18 O 2 = N-NH-COvNH 2 , 
is sparingly soluble, but crystallizes from warm ethyl acetate in 
long needles, melting at 191. Its oxime, C 10 H 18 O 2 = NOH, 
crystallizes in transparent prisms, which melt at 101 to 102. 

Gem-dimethyl adipic acid, C 8 H U O 4 , 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 ^em-dimethyl succinic 
acids. 

4. THUJAMENTHONE, C 10 H 18 O. 

On heating thujone at 280, it is converted into carvotanace- 
tone ; this differs from isothujone, and yields carvomeuthol (tetra- 
hydrocarveol) by reduction. When thujone is treated with dilute 
sulphuric acid, it is converted into isothujone ; on reduction, this 
compound forms an alcohol, C 10 H 19 OH, thujamenthol (dihydro- 
isothujol), which can be very readily distinguished from tetrahy- 
drocarveol (Wallach 1 ). 

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, 
n^, = 1.44708, at 20. It is optically inactive, and is stable 
towards a cold solution of potassium permanganate (Wallach). 

Thujamenthonoxime, C ]0 H lg NOH, crystallizes from dilute methyl 
alcohol in transparent prisms, and melts at 95 to 96. 

Isothujamenthonoxime, C 10 H 19 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 10 H 18 = N"-XH'CONH 2 , melts 
at 179. It is slowly reconverted into thujamenthone by boiling 
with dilute sulphuric acid. 

1 Wallach, Ber., 28, 1955; Ann. Chera., 286, 104. 



MENTHONE. 295 

Oxidation of thujamenthone. 1 When thujamenthone is carefully 
oxidized with potassium permanganate, it yields the ketonic acid, 
C 10 H 18 O 3 , which boils at 273, being converted into the keto-lac- 
tone, C 10 H 16 O 3 . The semiearbazone of the ketonic acid melts at 
174.5. A solution of sodium hypobromite changes the ketonic 
acid into a dibasic acid, C 9 H I6 O 4 , melting at 134.5. 

The keto-lactone, C 10 H 16 O 3 , is produced on oxidizing thujamen- 
thone with chromic acid; it melts at 41, and yields an oxime, 
melting at 156 (Wallach). 

According to Semmler, the above-mentioned ketonic acid boils 
at 273, being converted into the preceding keto-lactone, C 10 H 16 O 3 , 
melting at 43; the oxime melts at 155. On oxidation, the 
keto-lactone gives rise to ft-isopropyl laevulinic add. 

5. THUJAMENTHOL, C 10 H 19 OH. 

Thujamenthol or dihydroisothujol is obtained by reducing 
isothujone with sodium and alcohol. 2 It is a viscous liquid, hav- 
ing an odor resembling that of terpineol. It boils at 211 to 
213, has a sp. gr. of 0.895 and a refractive index, i\ D = 1.46345, 
at 22. It yields thujamenthone by oxidation with chromic acid 
(Wallach 2 ). 

6. MENTHONE, C 10 H 18 O. 

Menthone has the constitutional formula : 




H,C CH, 



It occurs, together with menthol, esters of menthol, menthene 
and limonene, in peppermint oil. 3 According to Power and 
Kleber, 3 the amount of menthoue in American oil of peppermint 
reaches 12.3 per cent. Andres and Andrejew 4 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 

i Wallach, Ber., 30, 423; Semmler, Ber., S3, 275. 

2 Wallach, Ber., 28, 1955. 

3 Schimmel & 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, 1 who heated menthol with potassium chro- 
mate and sulphuric acid in a sealed tube at 120 for ten hours. 
Later, Atkinson and Yoshida 2 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 3 have led to a 
very simple method for the preparation of menthone, and have 
further shown that its optical behavior is quite unusual. Men- 
thoue 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 remove 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. 

"Moriya, Journ. Chem. Soc., 1881, 77; Jahresb. Chem., 1881, 629. 
2 Atkinson and Yoshida, Journ. Chem. Soc., 1882, 50; Jahresb. Chem., 
1882, 775. 

3 Beckmann, Ann. Chem., 250, 322; 289, 362. 



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 1 ). 

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\ D = - 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, []^= 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-meuthone does not differ from the levo-modifica- 
tion in odor, boiling point, etc. Various preparations showed 
the specific rotatory powers : [] D = + 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- 

i Wallach, 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. 1 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 10 H 19 - 
NH 2 , together with some of the levorotatory isomeride. 2 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 monoehloride, C 10 H 17 C1, and a dichloride, C 10 H 18 C1 2 , 
are obtained. The monoehloride boils at 205 to 208, has the 
specific gravity at 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 (Berkenheim 3 ). 

According to Jiinger and Klages, 4 chlorotetrahydrocymene, 
C 10 H 17 C1, is obtained by the action of phosphoric chloride on 
menthone ; by successive treatment with bromine and quinoline 
it is converted into chlorodihydrocymene, C 1Q H 15 C1, 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 : 



HC CH 

y- 

C 3 H T 
3-Chlorocymene. 

'Beckmann, German patent, No. 42,458; Ber., 21, 321, Ref.; Ber., 22, 912. 
*Wallach, Ber., 24, 3992; 25, 3313; Wallach and Kuthe, Ann. Chem., 276, 
296. 

3 Berkenheim, Ber., 25, 693. 
'Jiinger and Klages, Ber., 29, 314. 



/3-METHYL ADIPIC ACID. 



299 



Dibromomenthone, 1 C 10 H 16 Br 2 O, is produced by adding two molec- 
ular proportions of bromine to I- or c?-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 10 H 16 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, 2 
C 10 H 8 OBr 6 ; the latter melts and decomposes at 148 to 149. 

/3-Methyl adipic acid, C 7 H 12 O 4 , is formed by the oxidation of 
menthone with potassium permanganate (Manasse and Rupe 3 ); 
it is also obtained, together with the so-called oxymenthylic acid, 
C 10 H 18 O 3 , 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 /9-methyl adipic acid 
from menthone by means of the following formulas : 




H,C CH 3 

Menthone. 



CH 2 
HG' COOH 



OH 

H 3 C CH g 
Oxymenthylic 
acid, the interme- 
diate ketonic acid. 



CH 3 

CH 

H 2 (J CH, 
H 2 C COOH 

COOH 

/?-Methyl adipic 
acid. 



'Beckmann and Eichelberg, Ber., 29, 418. 
"Baeyer and Seuffert, Ber., 34, 40. 
3Manasse and Rupe, Ber., 27, 1820. 



300 THE TEKPENES. 

Oxymenthylic acid is also formed by oxidizing menthone with 
chromic acid. 1 

When menthone is oxidized with Caro's reagent (potassium 
persulphate and concentrated sulphuric acid), it forms the corre- 
sponding e-lactone, 2 C 10 H 18 O 2 ; 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 10 H 18 NOH, is prepared by the following 
method (Beckmann 3 ). 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, 4 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 : 

\a\ D = - 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, []j,= 
61.16. This salt is converted into the levo-oxime by the action 
of sodium hydroxide. 

i Beckmann and Mehrlander, Ann. Chem., 289, 367. 
2Baeyer and Villiger, Ber., 32, 3625. 
3 Beckmann, Ann. Chem., 250, 329. 
'Wallach, Ann. Chem., 277, 157. 



ISO-LEVO-MENTHONOXIME. 301 

Dextro-menthonoxime, C 10 H 18 NOH, is prepared in the same 
manner as the levo-oxime ; it is an oil having a slight levoro- 
tatory power: [XU = 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 10 H 19 NH 2 , results by the reduction of 
levo-menthonoxime with alcohol and sodium. 

Several substances derived from levo-menthonoxime have been 
prepared by Wallach j 1 they are of special interest since they 
manifestly stand in a close relation to the olefinic members of the 
terpene series. 

Iso-levo-menthonoxime, 1 C 10 H lg 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. 2 ) 

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 levo-menthonoxime is 
dissolved in chloroform and treated with phosphorus pentachlo- 
ride, and the product is then mixed with water, iso-1-menthonox- 

i Wallach, Ann. Chem., 278, 302; 277, 154. 

*Mehrlander, Inaug. Diss. Breslau, 1887; Beckmann and Mehrlander, 
Ann. Chem., 289, 367. 



302 THE TERPENES. 

irne 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 20 H 3 _C1N 2 , 
is obtained. This amine crystallizes in well denned prisms, and 
melts at 59 to 60; it is levorotatory, [a\ D = 186.35, and 
yields stable salts as C 20 H 35 C1N 2 -2HC1. 

Phosphoric chloride converts dextro-menthonoxime into an iso- 
meric compound) melting at 88; an oily product results, together 
with the solid substance (Beckmann and Mehrlander *). 

Menthonitrile, ,C 9 H 17 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-1-menthonoxime. Thirty grams of the latter are dis- 
solved in eighty cc. 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-1-menthonoxime, and 
then, at a higher temperature, it is decomposed into menthonitrile 
and hydrochoric acid : 

I. 2C 10 H 18 NC1 = HC1 + C 20 H 35 C1N 2 ; 
II. CnHsBClN, = HC1 + 2C 9 H 17 CN. 

It can, therefore, be prepared from the pure base, C 20 H 35 C1N 2 . 
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, n^ = 1.44406, 
at 20. 

Menthonitrile differs from iso-1-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, 2 C 9 H 17 CONH 2 , 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, 2 C 9 H 17 COOH, results by the pro- 
longed action of alcoholic potash on the nitrile or acid amide ; it 

1 Beckmann and Mehrlander, Ann. Chem., 289, 367. 
zWallach, Ann. Chem., 296, 120. 




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 n D = 1.45109 at 20 ; it forms a sparingly 
soluble silver salt. Oxidation with permanganate yields /3-methyl 
adipic acid. 

Aminodecoic acid, 1 C 10 H 21 O 2 N, is prepared from menthoue 
isoxime ; it separates from water in well formed crystals, melting 
at 194 to 195. Nitrous acid converts it into decenoic acid, 
C ]0 H 18 O 2 , 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 10 H 19 NH 2 , and oxyhydro- 
menthonylamine, C 10 H 20 (OH)NH 2 ; the former is an aliphatic 
isomeride of menthylamine. If menthonylamine be treated with 
nitrous acid, an alcohol, menthocitronellol, C 1() H 19 OH, is formed ; 
when this alcohol is oxidized with chromic acid, an aldehyde, 
menthocitronellal, C 10 H lg O, is obtained. Dimethyl octylene fflycol, 
C 10 H 20 (OH) 2 , 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 10 H 20 O 2 , 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, n^= 1.4373. Its amide crystal- 
lizes from water and melts at 108 to 109 (Wallach). 

Menthone semicarbazones, C 10 H 18 = N-NB>CONH 2 . The de- 
rivative obtained from dextro-menthone melts at 172, and has 
the specific rotatory power, []^= 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]j,,= 3.67, under same condition as above. A 
mixture of the two modifications melts at 175 (Beckmann 2 ). 
According to Wallach, 3 menthone yields a semicarbazone, melting 
at 184. Rimini 3 has also obtained a semicarbazone from perni- 
trosomenthone, which melts at 192 to 193. 

Menthone semioxamazone, 4 C IO H 18 = N-C 2 O 2 N 2 H 3 , crystallizes 
from alcohol in wh te needles, and melts at 177. 

iWallach, Ann. Chem., 312, 171. 
*i*eckmann, Ann. Chem., 289, 362. 

s Wallach, Ber., 28, 1955; compare Rimini, Gazz. Chim., 30 [I.], 600; 
Beckmann, Ann. Chem., 289, 366. 
*Kerp and Unger, Ber., 30, 585. 



304 THE TERPENES. 

Pernitrosomentlione, 1 C 10 H 18 N 2 O 2 , 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 10 H 17 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, amyl 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 2 ). 

It may also be prepared in a yield of forty per cent, if acetyl 
chloride be used in place of hydrochloric acid (Baeyer 2 ). 

Bisnitrosomenthone reacts with alcoholic hydrochloric acid 
forming menihobisnitrosylic 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 10 H lfi O, which is apparently identical with menthenone, 
obtained by Kremers from nitrosomenthene (Baeyer 3 ). 

Menthoximic acid, C ]0 H 18 O 2 = NOH, is formed together with bis- 
nitrosomenthone, and is identical with the oxime of oxymenthylic 
acid, prepared by Beckmann and Mehrliinder 4 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, menthoximic 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 

1 Rimini, Gazz. Chim., 26 [II.], 502; 30 [I.], 600. 

2 Baeyer and Manasse, Ber., 27, 1912. 
= Baeyer, Ber., 28, 1586. 

Beckmann and Mehrlander, Ann. Chem., 289, 367. 






NITROMENTHONE. 305 

elements of water and is converted into menthoximic acid (di- 
methyl-(2, 6)-oximido-3-octanic acid) : 




+H 2 



H,C CH S HjC CH S 

Nitrosomenthone. Menthoximic acid. 





According to Oehler, 1 menthoximic acid melts at 103 ; according 
to Baeyer and Manasse, it melts at 98.5. 
Oxymethylene menthone, 

xC=CH(OH) 



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 2 ). 

Nitromenthone, C 10 H 17 O(NO 2 ), 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 U) H 17 - 
ONH 2 , which boils at 235 to 237; it forms amidomenthonoxime 

1 Baeyer and Oehler, Ber., 29, 27. 

2 Claisen, Ann. Chem., 281, 394. 

20 



306 THE TEKPENES. 

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 10 H 19 NO 4 , is formed by the action of sodium ethylate 
on nitromenthone ; it boils at 190 to 195 under 13 mm. pres- 
sure (Konowaloff 1 ). 

Benzylidene menthone, 3 C 10 H 16 O = CH-C 6 H 5 , 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 16 O = C 7 H 6 )'HC1, 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, 2 benzylidene menthone is formed by the 
action of benzaldehyde on sodium menthylate; it boils at 195 to 
196 (15 mm.), has the rotatory power, [0^= + 22.8 to + 
24.3, and forms the hydrobromide, melting at 115. 

Benzylidene menthonoxime, C 10 H 16 (NOH) = CH-C 6 H 5 , 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^NHj, which boils at 200 to 205 under 
10 mm. pressure. 

Benzyl menthol, 3 C 10 H 18 (OH>CH 2 -C 6 H 5 , 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 

i Konowaloff, Compt. rend., 121, 652; Ber., 31, 1478. 
"Marline, Compt. rend., 138, 41. 

sWallach, Ann. Chem., 305, 261; Ber., 29, 1595; compare Martine, Compt. 
rend., 133, 41. 



MENTHONE DICARBOXYLIC ACID. 307 

have the same composition, C, 7 H 25 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 17 H 24 , boiling at 
153 to 155 (10 mm.). 

Benzyl menthone, C 17 H 24 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 menthy famine. 

Menthone pinacone, 1 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. 2 

Menthone carboxylic acid, C 10 H 17 OCOOH, 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 10 H 16 O(NOH), and an ortho-dilcetone, C 10 H 16 O 2 , 
are formed ; the former is an oil, is soluble in alkalis, and yields 
menthone amine, C 10 H 17 ONH 2 , on reduction with zinc dust and 
acetic acid ; the ortho-diketone is a reddish oil, insoluble in alkalis. 

Menthone dicarboxylic acid, C, H 16 O(COOH) 2 , melts and decom- 
poses at 140 to 141. 

It should be mentioned that Flatau and Labb6 3 separated a 
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 10 H 18 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, 

JBeckmann, Journ. pr. Chem., 55 [II.], 14. 

2Qddo, Gazz. Chim., 27 [II.], 97. 

iFlatau and Labb6, Bull. Soc. Chim., 19 [III.], 788; compare Schimmel & 
Co., Semi-Annual Report, Oct., J898, 52. 

<Kondakoff, Journ. pr. Chem., 54 [II.], 433; Kondakoff and Bachtsch^eff, 
Journ. pr. Chem., 63 [II.], 49. 



308 THE TERPENES. 

the optical rotation, \_a\ D = 166', the index of refraction, 
n_o = 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 10 H 19 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, 
n /) = 1.45869, at 32; its benzoate melts at 82. When this 
menthol is treated with phosphoric oxide, it is converted into a 
menthene, C 10 H 18 , which boils at 166.5 to 168.5 (785 mm.), has 
the sp. gr. 0.8112 at 19, n^ = 1.45109, and [a~\ D = 1346'. 

Theisomeric, liquid menthol boils at 106.5 to 109 (18 mm.), 
has the sp. gr. 0.9041 at 21.6, n^ = 1.461793, and [a] D = 
-}- 2630'; it yields a levorotatory menthene. 

Neither of these isomeric menthols appears to be identical with 
the natural menthol. 

Sym-menthone 1 (1 , 3 -methyl isopropyl cyclohexanone-5), C 10 H 18 O, is 
formed by oxidizing s?/m-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, n^ = 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 10 H 19 OH. 

Menthol, 2 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 10 H 18 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 2() H 38 O 2 , is formed, together with menthol. 3 Levo- 
and dextro-menthone yield by both methods a strongly levoro- 
tatory mixture of menthols. From this mixture the natural 

1 Knoevenaugel and Wiedermann, Ann. Chem., 297, 169. 

'Oppenheim, 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. 

3 Beckmann, Journ. pr. Chem., 55 [II.], 14. 



MENTHOL. 309 

levo-menthol (m. p. 43), and a dextrorotatory isomenthol (m. p. 
78 to 81, [a] D = + 2) may be separated. 

Menthol and menthone 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 1 ). 

Menthol is also formed in the reduction of pulegone, 2 C 10 H 16 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 3 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, [a]^ = 59 6'. 

Chromic acid converts menthol into menthone. Phosphoric 
anhydride, zinc chloride, potassium bisulphate, etc., dehydrate it, 
forming menthene, C 10 H 18 ; this hydrocarbon is more readily pre- 
pared by distilling menthyl chloride with quinoline. According 
to Beckmann, 5 menthene also results by the action of concentrated 
sulphuric acid on menthol, whilst Wagner 6 finds that this reaction 
gives rise to a polymeric product, C 20 H 36 , together with cymene 
sulphonic acid and hexahydrocymene (menthane), C 10 H 20 . The 
transformation of menthol into cymene may be effected by heating 
with anhydrous copper sulphate at 250 to 280 (Briihl 7 ). Hexa- 
hydrocymene (" menthonaphthene "), C 10 H 20 , is produced by heating 
menthol with hydriodic acid and red phosphorus at 200 ; it boils 
at 169 to 170.5 (Berkenheim 8 ). 

Potassium permanganate oxidizes menthol, forming oxymen- 
thylic (ketomenthylic) acid, C 10 H lg O 3 , carbonic, formic, propionic 

'Beckmann, German Patent, No. 42,458; Ber., 22, 912. 
2 Beckmann and Pleissner, Ann. Chem., 262, 1. 
3 Bruhl, Ber., 21, 457. 

*Luginin, Ann. Chim. Phys. [5], 23, 387. 
5 Beckmann, Ann. Chem., 250, 358. 

6G. Wagner, Ber., 27, 1637; St. Tolloczko, Chem. Centr., 1895 [I.], 543; 
189S [I.], 105. 

7 Briihl, Ber., 24, 3374. 

s Berkenheim, Ber., 25, 686. 



310 THE TERPENES. 

and butyric acids, together with the dibasic /3-methyl adipic acid 
(Arth's l /3-pimelic acid), C 7 H 12 O 4 . 

Oxymenthylic acid (2, 6 -dimethyl octan-3-onoic acid), C 10 H 18 O 3 , 
is a thick liquid, sparingly soluble in water, and boils at 280 at 
ordinary pressure, or at 173 to 175 (15 ram.); with alkalis it 
forms crystalline salts which are readily soluble, whilst its silver 
salt is sparingly soluble. Its semicarbazone 2 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 2 
(isobutyryl methyl ketopentamethylene), C 10 H 16 O 2 ; 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 3 (m. 
p. 96.5), by treating with hydroxylamine. 

/3-Methyl adipic acid 4 (Arth's fi-pimelic acid), C 7 H 12 O 4 , melts at 
88.5 to 89. Mehrlander described it as normal propyl succinic 
acid, but Arth 5 proved the error of this statement. According 
to Semmler, 6 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 nien- 
thone. 

The sodium salt 7 of 1-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 mariner, melts at 39. 

Methylenic acetal of menthol 8 (dimentholic formal or dimenthyl- 
methylal), CH 2 (OC 10 H 19 ) 2 , 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 indiiferent to boiling acids and alkalis. 

!Arth, Ann. Chim. Phys., 7 [6], 440. 

*Baeyer and Oehler, Ber., 29, 27. 

3 Beckmann and Mehrlander, Ann. Chem., 289, 367. 

4 Manasse and Rupe, Ber., 27, 1818. 

s Arth, Ber., 21, 645, Ref. 

s Semmler, Ber., 25, 3515; 26, 774. 

7 Beckmann, Journ. pr. Chem., 55 [II.], 14. 

sBrochet, Compt. rend.', 128, 612; Wedekind, Ber., 34, 813. 



MENTHYL BENZOYL ESTER. 311 

Chloromethyl menthyl oxide, 1 C 10 H 19 OCH 2 C1, 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, [a] /) = 
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 21 H 40 O 2 . 

Menthyl acetoacetate, 2 C 14 H 25 O 2 , 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, [] D 56.6. 
Its phenylhydrazone melts at 81 to 83. 

Menthyl ethyl ether, C 10 H 19 OC 2 H 5 , 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, n^ = 1.44347, at 17.1 (Briihl 3 ). 

Menschutkin 4 investigated the speed of the ester formation of 
menthol and from his results determined that it is a secondary 
alcohol. 

Menthyl acetate, C 10 H 19 OCOCH 3 , is a thick, strongly refractive 
liquid, which boils at 224 and is levorotatory, []= 114. 
(Compare with Power and Kleber 6 ). 

Menthyl butyrate, C 10 H 19 OCOC 3 H 7 , boils at 230 to 240 and 
has the rotatory power, []/> = 88 8'. 

The following esters were prepared by Arth. 5 

Menthyl succinoxyl ester, C 10 H 19 O-CO-CH 2 -CH 2 -COOH, melts 
at 62, and has the specific rotatory power, [a] Z) = 59.63. 

Menthyl succinyl ester, C 2 H 4 (COOC 10 H, 9 ) 2 , 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] D = 81.52. 

Menthyl benzoyl ester, 7 C 6 H.COOC 10 H I9 , crystallizes in triclinic 
crystals, melts at 54, and has the rotatory power, [] /) = 
-90.92. 

iWedekind, German Patent, No. 119,008; Ber., 34, 813. 
*Cohn, Monatsh., 21, 200. 
sBrtihl, Ber., 24, 3375 and 3703. 
4 Menschutkin, Journ. Russ. Chem. Soc., IS, 569. 
s Arth, Ann. Chim. Phys. [6], 7, 433 to 499; Ber., 19, 436, Ref. 
sPower 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 6 H 4 -C(>OC 10 H 19 , melts at 

110, and has the specific rotatory power, [a] D = 105.55. 
Its magnesium salt is almost insoluble in water. 

Menthyl phthalyl ester, C 6 H 4 (COOC 10 H 19 ) 2 , separates from ether 
in triclinic crystals, and melts at 133. [a]^> = 94.72. 

Menthyl carbonate, CO(OC 10 H 19 ) 2 , 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 carbonyl 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 10 H 19 OCONH 2 , 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, [] /) = 
85.11. It combines with benzaldehyde, forming benzylidene 
menthyl carbamate; this compound melts at 143. 

Menthyl phenylcarbamate, C 10 H 19 O-CONHC 6 H 5 , is formed by 
the combination of phenylcarbimide with menthol ; it separates 
from alcohol in silky needles, melting at 111 (Leuckart 2 ). 

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, 4 C^H^OCS-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 10 H 19 O'CS'SCu, 
by heating. 

Methyl menthylxanthate, 4 O^H^OCS-SCHg, is formed when a 
solution of menthol in dry toluene is successively treated with 
sodium, carbon bisulphide, and methyl iodide; it melts at 39. 

1 Erdmann, Journ. pr. Chem., 56 [II.], 1. 
'Leuckart, Ber., 20, 115. 
'Beckmann, Journ. pr. Chem., 55 [II.], 14. 
*Bamberger and Lodter, Ber., 28, 213. 



MENTHYL CHLORIDE. 313 

When submitted to distillation, it yields methyl mercaptan and a 
menthene, C 10 H lg , of a high specific rotatory power, \a\ D = 114.77 
to 116.06. 

Menthyl dixanthate, 1 (C 10 H 19 O) 2 C 2 S 4 , is formed by the conden- 
sation of sodium menthylxanthate with iodine ; it forms yellow 
crystals. When distilled it gives a menthene, having the rotatory 
power, [a] D = 111.56. 

A number of the fatty acid esters of menthol have been pre- 
pared, and investigated by Tschugaeff. 2 

Menthyl chloride, C 10 H 19 C1, 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 3 ), C 10 H 19 C1, 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 zinc 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, 4 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 20 H 38 , 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, [a] /) = 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 menthyl 
chloride, as well as by the action of sodium on an ethereal solu- 
tion of menthyl iodide, indicates that the crude halogen esters of 

i TscMgaeff , Ber., 32, 3332. 

'Tschugaeff, Ber., 31, 364. 

aWaller, 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. 

'Kursanoff, Journ. Russ. Phys. Chem. Soc., 33, 289. 



314 THE TERPENES. 

menthol contain some secondary compounds, together with deriv- 
atives of tertiary menthol (Kursanoff). 

When 1-menthyl chloride is treated with zinc ethyl, it gives 
rise to ethyl menthane, C 10 H 19 .C 2 H 5 ; the latter boils at 209 to 
210 at 730 mm. pressure, has the sp. gr. 0.8275 at 0/0, and 
the specific rotation, [0;]^= 12 15'. 

Menthyl bromide (menthene hydrobromide 1 ), C 10 H 19 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 2 ), C 10 H, 9 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 3 C CH S 
Menthol. 

It has already been mentioned that when d- or 1-menthone is 
reduced with sodium, the corresponding d- and 1-menthols are not 
obtained, but rather a strongly levorotatory mixture of menthols 
is formed, from which the ordinary 1-menthol (m. p. 43, []/> 
= 49.3), and a dextrorotatory isomenthol may be separated. 

Isomenthol 3 is separated from the mixture by converting the 
menthols into their benzoyl esters; menthyl benzoate is a solid 
(m. p. 54), while isomenthyl 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] D = + 2.03. On oxidation with chromic 

'Kondakoff, Ber., 28, 1618. 

2 Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257; Berkenheim, 
Ber., 25, 696. 

3 Beckmann, Journ. pr. Chem., 55, 14. 



CIS-SYMMETRICAL MENTHOL. 315 

acid, isomenthol yields a dextro-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' 1 found that the best samples of oil from Barosma 
betulina and B. serratifolia contain about ten per cent, of hydro- 
carbons, C 10 H 16 (d-limonene and dipentene), sixty per cent, of 
ketomenthone, C 10 H 18 O (see under menthone), and five per cent, 
of diosphenol. 

Diosphenol, C 10 H lg O 2 or C 10 H 16 O 2 , is an inactive, phenolic alde- 
hyde, and melts at 82. On reduction with hydriodic acid and 
phosphorus at 210, it yields a hydrocarbon, C IO H 20 , 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 10 H 20 O 2 , and a stereomeric, liquid 
glycol, C 10 H w O a . 

The inactive menthol, C 10 H 19 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, n^ = 1.464456. It yields an inactive iodide, 
C 10 H 19 I, which boils at 126.5 (17 mm.). When this iodide is 
treated with alcoholic potash, an active menthene, C 10 H lg , results, 
which boils at 168 to 169, has the sp. gr. 0.8158 at 19.8, 
n D = 1.45909, and [a~\ D = 37'. 

The crystalline glycol, C, H 20 O 2 , 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 10 H 19 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 10 H 20 O 2 , is stereomeric with the crystalline 
glycol ; it boils at 141.5 to 145 (13 mm.), has the sp. gr. 0.995 
at 21.6, andnp= 1.47877. 

In conclusion, two alcohols, C 10 H 19 OH, isomeric with menthol, 
but synthetically prepared, should be mentioned. 

Cis-symmetrical menthol (cis-1, 3-methyl isopropyl cyclohexanol- 
5), C 10 H 19 OH, is an alcohol, isomeric with natural menthol, which 
Knoevenagel ? prepared synthetically by the action of hydriodic 
acid, zinc dust and glacial acetic acid on raws-hexahydro-l, 3, 5- 
carvacrol, C 1(J H 17 OH. It boils at 226 to 227 (760 mm.), has 
a specific gravity 0.9020 and refractive index, n^ = 1.46454, at 

Kondakoff and Bachtsche"eff, Journ. pr. Chem., 63 [II.], 49. 
2 Knoevenagel and Weidermann, Ann. Chem., 297, 169. 



316 THE TEEPENES. 

13.6, and a molecular refraction, M = 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 phenylur ethane crystallizes from 
a mixture of alcohol and petroleum ether, and melts at 88. The 
chloride, bromide and iodide are liquids. 

An alcohol, 1 C IO H 19 OH, isomeric with, and having the same 
structure as, natural 1-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 18 , boiling at 165 to 167. 

8. TERTIARY CARVOMENTHOL, C 10 H 19 OH. 

Tertiary carvomenthyl iodide, C 10 H 19 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 10 H 19 I, be dissolved 
in acetic acid, and decomposed with silver acetate, it is partially 
reverted into carvomentheue, while the remaining portion is con- 
verted into the acetate of tertiary carvomenthol (Baeyer 2 ). 



H 3 C CH 
H,C CH Z 



C 3 H 7 

Carvomenthene. Tertiary carvomenthyl Tertiary carvomenthyl 

iodide. acetate. 

Tertiary carvomenthol is obtained by the hydrolysis of its 
acetate. It 3 is also produced by treating carvomenthyl chloride 
or bromide with moist silver oxide ; a small quantity of the com- 
pound, C 10 H 22 O 3 (m. p. 101 to 102), is formed at the same time. 

] S. H. Baer, Inaug. Diss., Leipzig, 1898; Schimmel & Co., Semi- Annual 
Keport, Oct., 1898, 49. 
zBaeyer, Ber., 26, 2270. 
3 Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257. 





TERTIARY MENTHYL, METHYL ETHER. 



317 



Tertiary carvomenthol has 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 ; l 
this is a heavy oil, which yields carvomenthene, boiling at 174.5, 
when distilled with quinoline. 



9. TERTIARY MENTHOL, C 10 H 19 OH. 

Tertiary menthyl 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 2 ). 






Menthene. 



Tertiary menthyl 
iodide. 



C S H T 

Tertiary menthyl 
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. 1 

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. 3 

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 10 H ]9 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 10 H lfl OCH 3 , is obtained, together 
with a monomethyl terpine, by the following method. 

'Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257. 

2 Baeyer, Ber., 26, 2270. 

sMasson and Reychler, Ber., 29, 1843. 



318 THE TEEPENES. 

The methyl ether of crystallized terpineol (ru. 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 10 H I8 (OCH 3 )OCOCH 3 , is also formed by the re- 
placement of the iodine atom in the above-mentioned hydriodide 
with the acetyl group. This acetate yields monomethyl terpine 
by boiling with sodium hydroxide. The terpine is separated 
from meuthyl 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 1 ). 

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. 2 ) 

10. TERPINE, C 10 H 18 (OH) 2 . 

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 2 CH 2 

H 2 C in 2 and 

UC1 




II S C CH 3 
Dipentene dihydrochlorid*. 

i Baeyer, Ber., 26, 2560. 

sKondakoff, Ber., 28, 1618; Journ. pr. Chem., 60 [II.], 257. 



TEANS-TEKPINE. 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 : 

HOOC CH CH 2 CO 



CH CH 2 CC 

4- -i 



H 3 C CH S 

Moreover, the oxidation of terpine 1 with chromic anhydride 
yields the keto-lactone, C 10 H 16 O 3 , 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 ; the two compounds would then be represented by the for- 
mulas : 





and 



H 3 C CH 3 
Dipentene dihydrochloride. 

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 2 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 2 ). 

'Tiemann and Schmidt, Ber., 28, 1781. 
2 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 1 ). 

While many terpenes yield traus-dipentene dihydrochloride and 
dihydrobromide 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 10 H 18 (OH) 2 -f- H 2 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 2 do not re- 
gard terpine hydrate as a terpine containing water of crystalliza- 
tion, but rather as an aliphatic alcohol. 

Terpine hydrate, C 1() H 18 (OH) 2 + H 2 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 W r iggers 3 and Deville, 4 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, 5 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, 6 whose method was employed by Wal- 
lach, 7 a mixture of eight parts of turpentine oil, two parts of alco- 

1 Baeyer, Ber., 26, 2865. 

2 Tiemann and Schmidt, Ber., 28, 1781. 
3 Wiggers, Ann. Chem., 57, 247. 

* Deville, Ann. Chem., 71, 348. 
s Tilden, Jahresb. Chem., 1878, 638. 
sHempel, Ann. Chem., 180, 73. 
'Wallach, Ann. Chem., 227, 284. 



TEEPINE - HYDEATE. 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. 1 

Terpine hydrate is also formed when dipentene dihydrochloride 
is treated with aqueous alcohol, 2 or when limonene hydrochloride 
is mixed with water and allowed to stand for some time. 3 It re- 
sults if terpineol be shaken with dilute acid for a considerable time. 

It crystallizes from alcohol in transparent, well defined, mono- 
clinic 4 prisms, and dissolves in 200 parts of cold, and twenty-two 
parts of boiling water; 5 14.49 parts of terpine hydrate dissolve 
in 100 parts of eighty-five per cent, alcohol 4 ; it is insoluble in 
ligroine. Contrary to the earlier publications, Wallach 6 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 10 H 18 (OH) 2 , 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 
believe*! that a homogeneous substance resulted by heating terpine 
hydrate with dilute acids; Tilden 7 recognized, however, that an 
oxidized compound, C 10 H 18 O, was formed, together with, terpenes, 

i Wallach, Ann. Chem., 227, 284. 

*Flawitzky, Ber., 12, 2358. 

aWallach and Kremers, Ann. Chem., 270, 188. 

'Deville, Ann. Chem., 71, 348. 

sBlanchet and Sell, Ann. Chem., 6, 268. 

a Wallach, Ann. Chem., 230, 247. 

i Tilden, Jahresb. Chem., Jf878, 639. 

21 



322 THE TEKPENES. 

C 10 H lg . 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, 1 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-acdyl ester of terpine, C 10 H 19 O(C 2 H 3 O 2 ), was obtained by 
Oppenheim 2 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 10 H 20 , 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 3 ). 

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 4 ). 

i Wallach, 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. 

2 Oppenheim, Ann. Chem., 129, 157. 

s Schtschukarew, Ber., 23, 433, Ref. 

* Hempel, Ann. Chem., 180, 71. 



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 1 ). 

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 10 H 16 O 3 , 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 10 H 18 (OH) 2 . 

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 10 H 18 O. 

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, 2 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 10 H 18 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 3 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, 4 in eucalyptus oil by Jahns 5 and by Wallach and Gilde- 
meister, 6 in oil of sage, laurel leaf oil and laurel berry oil by 
Wallach. 7 It also occurs in the oil of cheken-leaves, galangal 

Tiemann and Schmidt, Ber., 28, 1781. 
2 Wallach and Brass, Ann. Chem., 225, 291. 
a Wallach, Ann. Chem., 225, 315. 
'Weber, Ann. Chem., 238, 90. 
sjahns, Ber., 17, 2941. 

b Wallach and Gildemeister, Ann. Chem., 246, 278; compare Arch. Phann., 
1885, 52. 

i Wallach, 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, etc. 

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, 2 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 3 ). 
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 Eucalyptus 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 4 boils at 176, has 
a sp. gr. 0.930 at 15, and a refractive index, n^ = 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, n c = 1.45590. 5 

It combines with concentrated phosphoric acid, forming the 
compound, C 10 H 18 OH 3 PO 4 , which may also be employed for the 
preparation of pure cineole from eucalyptus oil. 6 It also forms 
addition-products with a- and /3-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. 

1 Wallach, Ann. Chem., 239, 20; 275, 106. 

2 Bouchardat and Voiry, Compt. rend., 10 6, 663. 
'Wallach and Brass, Ann. Chem., 225, 291. 

4 Schimmel & Co., Semi-Ann ual Report, April, 1895, 34. 
sWallach and Pulfrich, Ann. Chem., 2^5, 195. 
6 Scammel, German patent, No. 80,118. 



CINEOLE HYDROBKOMIDE. 325 

Cineole is generally regarded as an anhydride of terpine : 





H 8 C CH S H 3 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 1 ). 

Cineole hydrocbloride, (C 10 H 18 O) 2 'HC1 (?), 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 Bitter f 
according to these chemists, the hydrochloride has the formula, 
C 10 H 18 OHC1. 

Cineole hydrobromide, C 10 H 18 (OH)Br, was obtained in an im- 
pure condition by Hell and Hitter ; 4 it was also prepared by Wal- 
lach and Brass. 

In order to prepare it, cineole is dissolved in petroleum ether, 

i Wallach, Ann. Chem., 239, 22. 
Volkel, Ann. Chem., 87, 315. 
Hell and Ritter, Ber., 17, 1977. 
'Hell 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 at56to57. 
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 10 H 18 OBr 2 , 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 10 H 18 OI 2 , 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, 1 C 10 H 18 O'C 4 I 4 NH, is well 
adapted for the rapid detection and isolation of cineole in vola- 
tile oils. A small quantity of iodol, C 4 I 4 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 10 H 16 O 6 . 

Cineole is oxidized by potassium permanganate, yielding cine- 
olic acid, oxalic acid, acetic acid and carbonic acid (Wallach and 
Gildemeister 2 ). 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. 

^irschsohn, Pharm. Zeitschr. f. Russl., 32, 49 and 67; Bertram and 
Walbaum, Archiv. d. Pharm., 235, 178. 

2 Wallach and Gildemeister, Ann. Chem., 246, 265. 



ETHYL HYDROGEN CINEOLATE. 327 

One hundred cc. 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 oflP, 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 1 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 alcohol and ether, more spar- 
ingly in chloroform. By means of its strychnine salt it is resolved 
into the optically active cineolic acids. 1 

The following compounds are derivatives of racemic cineolic 
acid. 

Calcium cineolate, C 10 H 14 O 5 Ca + 4H 2 O, 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, 2 C g H 14 O(COOCH 3 ) 2 , is obtained by satu- 
rating a methyl alcoholic solution of cineolic acid with hydro- 
chloric acid gas. It melts at 31. 

Ethyl cineolic ester, C 8 H 14 O(COOC 2 H 5 ) 2 , 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, 3 

)H 

C a H 6 

i According to Rupe and Ronus (Ber., S3, 3544), pure, inactive cineolic 
acid melts at 204 to 206. 

zWallach, Ann. Chem., 258, 319. 
3Rupe, Ber., 33, 1133. 



328 THE TERPENES. 

crystallizes from dilute alcohol in slender needles, and melts at 
99 to 100. 

Oineolic anhydride, 1 C 10 H 14 O 4 , 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 1 ). 

Cineolic piperidide, 

/CONC 6 H 10 

C - H "<COOH 

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 8 H u O*- 
CONC 5 H 10 . 

Cineolic allylamide, 

/CONHC 3 H 5 
C 8 H M 0< 

XX)OH 

is sparingly soluble in ether, crystallizes from a mixture of methyl 
alcohol and ether, and melts at 126. 
Cineolic dietliylamide, 

,CON(C,H 5 ) S 



*\j\ji 

C ' H "<x 



)OH 

melts at 162 to 163. 
Cineolic anilide, 

.CONHCgHs 

:OOH 

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. 

1 Wallach and Elkeles, Ann. Chem., 271, 21. 



CINEOLIC PHENYLHYDRAZIDE. 



329 



Cineolic para-toluidide, 

/CONHC 8 H 4 CH, 

C ' H "<COOH 

separates from a mixture of ether and methyl alcohol in well 
defined crystals, melting at 125 to 126. 
Cineolic phenylhydrazide, 

C 8 H M 0/ 

X COOH 

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 10 H 14 4 = CO 4- C0 2 + C 8 H U 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 : 

H, 



COOH 
COOH 






CH S 

Oxide (hypothetical). 



H S C CH, 

Cineolic anhydride. 



CH S 

^>C=CH CK, CH, CO CH, 
CHs 



Methyl hexylene ketone. 



'For more recent formulas of cineole and cineolic acid, see Wallacb, 
Ann. Chem., 291, 350. 



330 THE TERPENES. 

Methyl hexylene ketone (methyl heptenone), C 8 H U O, is a liquid, 
having an agreeable odor like that of amyl acetate ; it boils at 
173 to 174, has a refractive power, n c = 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, n^ = 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 1 melts at 136 to 138. 

Meta-dihydroxylene, C 8 H 12 , 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 : 





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 2 must be consulted. 

An unsaturated alcohol, 3 methyl heptenol (methyl hexylene car- 
binot), C 8 H 15 OH, is formed, when methyl hexylene ketone is re- 

'Tiemann and Kriiger, Ber., 28, 2124. 

2L6ser, 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 Le"ser, Bull. Soc. Chim., 17 [III.], 748; Barbier, Compt. rend., 
128, 110; Verley, Bull. Soc. Chim., 17 [III.], 175; Tiemann, Ber., 31, 2989; 
32, 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 g H 16 O. This reaction is quite 
analogous to that by which the homologous alcohol, C 9 H 17 OH, 
obtained from methyl heptylene ketone, is converted into an 
isomeric oxide, C 9 H 18 O (see thujone). 

Methyl hexylene oxide, C 8 H O, boils at 127 to 129, has a 
specific gravity of 0.850 and index of refraction, n^ = 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 1 obtained from f-pentylene glycol. 

CH S CH CH, 
CH S -CH(OH) CH a -CH,-CH,(OH)=H,O+ O/ 

CH, CH, 

y-Pentylene glycol. y-Pentylene oxide. 



=CH CH, CH, CH(OH) CH 3 = 

CH 

CH, CH CH, 

Methyl hexylene carbinol. Methyl hexylene oxide. 

Wallach and Elkeles also prepared methyl hexylene ketone by 
the distillation of cineolic amides : 

/CONHR 

C 8 H 14 0< ^RNHj-fCO+COj+CgHnO. 

\COOH 

When cineolic acid is submitted to dry distillation, it is par- 
tially converted into its anhydride, and partially into a liquid 
monobasic acid, C 9 H 16 O 3 (b. p. 135 under 11 mm.), together with 
some methyl hexylene ketone : 2 C 10 H 16 O 5 = CO a + C 9 H 16 O S . 

Wallach and Elkeles have described the methyl ester of this 
monobasic acid, C 9 H 16 O 3 ; 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. 

i Perkin and Freer, Ber., 19, 2568; compare Lipp, Ber., 18, 3285; 19, 2843. 
Wallach, Ann. Chem., 246, 274; 258, 321; 271, 26; Rupe, Ber., 55, 1129. 



332 THE TERPENES. 

According to Rupe, 1 when cineolic acid is heated with water at 
160 for three hours, it yields a mixture of two isomeric acids, 
C 9 H 16 O 3 ; one of these acids is termed a-cinenic acid, and the other 
is called methoethylol-5-hexene-2-acid-6. 

a-Cinenic acid, C 9 H 16 O 3 , is stable towards potassium permanga- 
nate, is not acted upon by bromine, does not react with phenyl- 
hydrazine, hydroxylamlne, 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-S-chloro-a-methoethylol-5-hexoate, C 8 H 15 C1(OH)'COOC 2 H 5 , 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 d-bromo-a-oxyisopropyl hexe- 
noic acid, C 8 H 15 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 8 H 15 (OH) 2 'COOH. 
Cinogenic acid (^-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. 

/9-Cinenic acid, C 9 H 16 ) 3 , 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, n^ = 1.4486, and forms a characteristic 
calcium salt, which crystallizes from water in needles ; the corre- 
sponding salt of a-cinenic acid is amorphous. /3-Cinenic acid may 
be converted into cinogenic acid in the same manner as the a-acid. 

Methoethylol- 5 -hexene-2 -acid- 6 (a-oxy isopropyl- J Y -hexenoic acid) , 
C 9 H 16 O 3 , is isomeric with the cinenic acids and is formed together 
with a-cinenic acid by the action of water on cineolic acid. 

iRupe, Cliem. 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 /9-oxy-acid, and when distilled under atmospheric pres- 
sure, it loses one molecule of water, yielding a-iso-propylidene- 
dv-hexenoic add (methoethene-5-hexene-2-acld-6\ C 9 H 14 O 2 ; 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 add, C^H^OgN,^ 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 dextro- 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 10 H 16 O 5 + H 2 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\ D 
= + 18.56 and 19.10. The racemic acid melts 2 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. 

iRupe and Ronus, Ber., 33, 3541. 

* According to Wallach and Gildemeister, the inactive acid melts at 196" 
to 197. 



334 THE TERPENES. 

d-Cineolic anhydride, C 10 H 14 O 4 , 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\ D = + 45.37, at 20 in a benzene solution. 

13. TERPAN-1, 4, 8-TEIOL, C 10 H ir (OH) s . 

This compound has already been mentioned as an oxidation 
product of Baeyer's J 4(8) terpen-l-ol (see page 273). Its con- 
stitution may be regarded as proved by its transformation into 
tribromoterpane, melting at 110. 

14. TRIOXYHEXAHYDROCYMENE, C 10 H 17 (OH) 3 . 

This substance melts at 121 to 122. (Compare under ter- 
pineol, page 262.) 

15. PINOLE HYDRATE, C 10 H 17 OOH. 

This compound is described under pinole ; see page 276. 

16. LIMONETROL, C 10 H 16 (OH) 4 . 

Limonetrol is prepared by the following method suggested by 
G. Wagner. 1 

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 10 H 16 O(OH) 2 . 
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. 

iQ. Wagner, Ber., 23, 2315. 



KETO- AND OXY-HYDROCYMENES ; TABLE OF. 



335 



M 
O 



M 
W 

IS 




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 ) 

1. PINYLAMINE, C 10 H 15 NH 2 . 

Pinylamine is formed by the reduction of nitrosopinene, the 
compound obtained by the action of alcoholic potash on pinene 
nitrosochloride : 

C 10 H 15 NO + 4H = H 2 + C 10 H 15 NH 2 . 

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 zinc 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 2 ). 

The free base is produced by treating pinylamine nitrate with 
sodium hydroxide ; it is dried over potash, and distilled in vacuum. 

i A 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. 

2 Wallach and Lorentz, Ann. Chem., 268, 197; compare Ann. Chem., 258, 
346, and Ber., 24, 1549. 

336 



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 borueol. 
Its specific gravity at 17 is 0.943. Pinylamine is an unsaturated 
compound. 

Pinylamine hydrochloride, C 10 H ]5 NH 2 -HC1, 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 ]0 H 16 O ; this oxygenated com- 
pound yields an oxime when treated with hydroxylamine. The 
decomposition of pinylamine hydrochloride is represented by the 
equation : C 10 H 15 NH 2 -HC1 = NH 4 C1 + C 10 H 14 . 

Pinylamine platinochloride, (C 10 H 17 N-HCl) 2 PtCl 4 , is sparingly 
soluble in water, but freely in alcohol ; it decomposes without 
melting when heated above 200. 

Pinylamine nitrate, C 10 H 15 NH 2 -HNO 3 , is difficultly soluble in 
water. It crystallizes from dilute alcohol in long, colorless 
needles. 

Pinylamine sulphate, (C 10 H 15 NH 2 ) 2 -H 2 SO 4 , forms small needles, 
and decomposes above 200 without melting. 

Pinylamine thiocyanate, C 10 H 1S NH 2 -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 10 H 15 NH 2 ) 2 H 2 C 2 O 4 , 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 10 H 15 NH-COCH 3 , 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 10 H 15 NH-COC 6 H 5 , 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 10 H 15 NH-CO-NH 2 , is produced by treating 
pinylamine hydrochloride with potassium cyanate ; it crystallizes 
in long, colorless needles, and melts at 156. 

Benzylidene pinylamine, C 10 H 15 N= CH-C 6 H 5 , 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 10 H 15 N = CH'C 4 H 3 O, 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 10 H ]5 N = CH-C 6 H 4 OH, forms 
lustrous, yellow crystals, and melts at 108 to 109. 

The halogen alkyls react vigorously with pinylamine. 

Pinocarveol, 1 C 10 H 15 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 : 




H,C CH, 
2. AMIDOTEREBENTENE, C 10 H 15 NH 2 . 

Pesci and Betelli 2 also converted pinene into an amine, 
C 10 H 15 NH 2 , which is isomeric with pinylamine. It is obtained 
from nitroterebenteue. 

'Wallach, Ann. Chem., 277, 149; Wallach and Smythe, Ann. Chem., 300, 
286. 

"Pesci and Betelli, Gazz. Chim., 16, 337; Jahresb. Chem., 1886, 613. 



PINENE PHTHALAMIC ACID. 339 

Nitroterebentene, C 10 H 15 NO 2 , is obtained by treating French or 
American l 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 2 ). 

It is a yellow liquid, having an odor of peppermint, and is 
readily decomposed on heating. 

Amidoterebentene is prepared by reducing nitroterebentene with 
zinc 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 under*a 
pressure of 9 mm. (Pesci and Betelli). 

Amidoterebentene hydrochloride, C 10 H 15 NH 2 - HC1, obtained from 
either levo- or dextro-pinene, is optically levorotatory, 1 [a] D = 
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, 

co 



prepared by Pesci 3 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, 

/COOH 
C 6 H/ 

X CONHC 10 H 15 

results by decomposing its potassium salt with hydrochloric acid. 

1 Pesci, Gazz. Chim., 18, 219; Jahresb. Chem., 1888, 899. 

2 Pesci and Betelli, Gazz. Chim., 16, 337; Jahresb. Chem., 1886, 613. 

3 Pesci, Gazz. Chim., 21 (I.), 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 10 H 15 N(CH 3 ) 3 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. BORNYL AMINES, C 10 H 17 NH 2 . 

Bornylamine was discovered by Leuckart and Bach, 1 who ob- 
tained it by the treatment of camphor with ammonium formate, 
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. 2 

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 [] /) = 18 35' 41" 
(Leuckart and Bach). 

Bornylamine hydrochloride, C 10 H 17 NH 2 -HC1, is precipitated in 
the form of small, white needles when hydrogen chloride is passed 
into an ethereal solution of bornylamine. When the hydrochloride 

'Leuckart and Bach, Ber., 20, 104. 

"Wallach 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 10 H 17 NH 2 -HC1 ) 2 PtCl 4 , dissolves readily in 
hot water and alcohol, and forms golden-yellow scales. 

Bornylamine hydrobromide, 1 C 10 H, 7 NH 2 -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, 2 C 10 H 17 NH 2 -H 2 SO 4 , 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 10 H 17 NH 2 -C 4 H g O 4 + H 2 O, is easily solu- 
ble in water, almost insoluble in cold alcohol, and crystallizes 
from hot alcohol in needles. 

Bornylamine picrate, 1 C 10 H 17 NH 2 -C 6 H 2 (NO 2 ) 3 OH, forms golden- 
yellow needles, which are almost insoluble in ether. 

Bornylamine is very readily converted into the carbylamine de- 
rivative. 2 

When bornylamine or its formyl compound is heated at 200 
to 210 with acetic anhydride, it is decomposed into camphene, 
CLH,,, and ammonia : l 

10 I u- 



Formyl bornylamine, 2 C, H 17 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, 2 C 10 H ]7 NH-COCH 3 , 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 alcohol. It forms leaflets, melting at 1 41 , 
and is nearly insoluble in ligroine. 

Benzoyl bornylamine, C 10 H 17 NH>COC 6 H 5 , is prepared like the 
preceding compound, and is similar to it in appearance and solu- 
bility. It melts at 131. 

iWallach and Griepenkerl, Ann. Cliem., 26'J, 347. 
zLeuckart and Bach, Ber., 20, 104. 



342 THE TERPENES. 

Bornylcarbamide, 1 C 10 H 17 NH>C(>NH 2 , 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 bornylcarbamide, 1 C 10 H 17 NH-CO-NHCH 3 , results by 
mixing the ethereal solutions of methyl isocyanate and bornyl- 
amine. It melts at 200. 

Phenyl bornylcarbamide, 1 C 10 H 17 NH-CONHC 6 H 5 , separates in 
the form of silvery leaflets when pheuyl isocyauate is added to an 
ethereal solution of bornylamine. It melts and decomposes at 
248. 

Bornyl phenylthiocarbamide, 1 C 10 H 17 NH>CS-NHC 6 H 5 , 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, 2 CS(NHC ]0 H 17 ) 2 , 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, 2 the alkyl 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 10 H 17 NH-CH 2 C 6 H 5 , 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 methyl iodide, forming a meth- 
iodide, which crystallizes from hot alcohol in thin needles, and is 
very difficultly soluble in hot water. 

Benzylidene bornylamine, 2 C IO H 17 N = CHC 6 H 5 , is an oil ; its 
hydrochloride, which crystallizes in small needles, and its platino- 
chloride have been analyzed. 

I^The other condensation-products of bornylamine with aldehydes 
are liquids. 

Bornylamine is very stable towards fuming nitric acid (Wal- 
lach and Griepenkerl 2 ). 

iLeuckart and Bach, Ber., 20, 104. 

2 Wallach 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 10 H 16 O or C 10 H 18 O. A compound having the same 
melting point has also been observed by Lampe 1 in the decompo- 
sition of bornylamine nitrite. 

Dibornylamine, (C ]0 H 17 ) 2 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 2 ). 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 crystallizes from alcohol in lustrous plates, melting at 
43 to 44." 

Dibornylamine hydrochloride, C 20 H 35 N-HC1, 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-HNOg, is sparingly soluble in 
water ; it is well adapted for the separation of dibornylamine 
from bornylamine. 

A compound, C 2 H 35 N'HBr*Br 2 , 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 20 H 3< .N'HNO 2 , 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, 3 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 10 H 17 NH 2 . One of these melts at 163, is 
dextrorotatory, [a] D = + 45.5, and is termed bornylamine, whilst 
the other melts at 180, is levorotatory, [a\ D = 31.3, and is 

1 Lampe, Inaug. Diss., GSttingen, 1889, 41. 

2 Wallach and Griepenkerl, Ann. Chem., 269, 347. 

sMartin 0. Forster, Journ. Chem. Soc., 73, 386; 75, 934 and 1149. 



344 THE TERPENES. 

called neobornylamine. (Leuckart and Bach's " bornylamine " 
melts at 159 to 160, and is levorotatory, [] /) = 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 amyl alcohol, are treated in a reflux apparatus with seventy- 
five grams of sodium ; the process requires about four hours, after 
which 100 cc. 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- 
amiue. 

Bornylamine, C 10 H 17 NH 2 , 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 10 H 17 NH 2 , 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- 



DERIVATIVES OF BORNYLAMINE ; TABLE OF. 



345 



ing on the optical activity of certain derivatives of bornylamine," 
the original publications l must be consulted. 



o? 

CO 10 

I-H CO 

I o 
o CO 

OJ r-H 
O 



I- 
CO 



O O 

* co 



o o 

T*H OO 

CO "t 1 



a a a a a 



I oooo 



a a a a 



a .s a a a 



a a 
a a 



i si (i 



a .s 



a a a 



a 



.2 s > 



- 'a 



a .r 1 

PH S 



i Martin 0. Forster, Journ. Chem. Soc., 75, 934 and 1149. 



346 THE TEKPENES. 



4. CAMPHYLAMINES, C 9 H 15 CH,NH 2 . 

a-Camphylamine is produced by the reduction of the nitrile of 
-campholenic acid (caraphoroxime anhydride) : 

C 9 H I5 CN4-4H=C 9 H 15 CH !! NH 2 . 

The reduction may be accomplished by zinc and alcoholic hy- 
drochloric acid (Goldschmidt and Koreif 1 ), or by sodium and 
alcohol (Goldschmidt 2 ). Goldschmidt and Schulhof, 3 who made 
a special study of camphylamine, employed the last-mentioned 
method for its preparation. 

a-Camphylamine 4 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, [#].= +6. 

a-Camphylamine hydrochloride, 1 C 10 H 19 N-HC1, forms colorless, 
thin, orthorhombic plates ; it is readily soluble. 

a-Camphylamine platinochloride, 3 (C 10 H 19 N) 2 H 2 PtCl 6 , crystallizes 
in brilliant, yellow leaflets, which decompose without melting when 
heated above 200. The mercuriochloride 2 forms lustrous, ortho- 
rhombic plates. 

Acid a-camphylamine oxalate, C 10 H 19 N < C 2 O 4 H 2 +^H 2 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 10 H 19 N) 2 H 2 SO 4 -f H 2 O, crystallizes 
in orthorhombic prisms, which are readily soluble. It cannot be 
recrystallized from hot water without decomposition. 

a-Camphylamine dichromate, (C 10 H 19 N) 2 H 2 Cr 2 O 7 , is precipitated 
from a solution of camphylamiue hydrochloride by potassium 
dichromate. 

a-Camphylamine picrate forms slender, yellow needles, and melts 
with decomposition at 194. 

Benzoyl a-camphylamine, C 10 H, 7 NH-COC 6 H 5 , 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, 

'Goldschmidt and Koreff, Ber., 18, 1632. 
zGoldschmidt, Ber., 18, 3297. 
"Goldschmidt and Schulhof, Ber., 19, 708. 
'Tiemann, Ber., 29, 3006. 



FENCHYLAMINE. 347 

and crystallized from ligroine. It separates in colorless prisms, 
melting at 75 to 77. 

a-Camphyl phenylthiocarbamide, C 10 H 17 NH-CS-NHC 6 H 5 , is pre- 
pared by the action of phenylthiocarbimide on an ethereal solution 
of the base ; it is crystallized from ligroine, and recry stall i zed 
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, 1 C 10 H 17 NITCS-SNH 3 -- 
C 10 H 17 , is obtained by the action of carbon bisulphide on cam- 
phylamine. 

a-Camphyl thiocarbimide 2 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 reaction. 

/9-Campliylamine, 2 C 10 H 17 NH 2 , is produced by the reduction of 
/3-campholenonitrile, C 9 H 15 CN, in alcoholic solution with sodium. 
It is optically inactive, and boils at 196 to 198. 

5. FENCHYLAMINE, C 10 H 17 NH 2 . 

Wallach 3 obtained this compound by treating fenchone with 
ammonium formate, and also by reducing fenchonoxime with 
sodium and alcohol. 4 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. 5 

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 feuchylamine (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 

iQoldschmidt and Schulhof, Ber., 19, 708. 

"Tiemann, Ber., 80, 242. 

sWallach, Ann. Chem., 263, 140. 

Wallach, Ann. Chem., 272, 105. 

Wallach, Griepenkerl and Luhrig, 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, 1 
twenty-five grams of sodium are added rather rapidly to a so- 
lution of twenty -one grams of the oxime in 100 cc. 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. 2 

Fenchylamine hydrochloride, C 10 H 17 NH 2 'HC1, dissolves in water 
and alcohol, and by slow crystallization is obtained in transparent 
prisms. It is readily soluble in ether. 

The platinochloride, (C 10 H 17 NH 2 ) 2 H 2 PtCl g , 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 10 H 17 NH 2 'HNO 2 , 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, 3 C 10 H 17 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. 

Wallach, Ann. Chem., 272, 105. 

*Wallach Griepenkerl and Luhrig, Ann. Chem., 269, 358. 

sWallach, Ann. Chem., 263, 140. 



METHYL FENCHYLAMINE. 349 

Acetyl fenchylamine, 1 C 10 H 17 NH-COCH 3 , 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, 2 C 10 H 17 NH-COC 2 H 5 , melts at 123. 

Butyryl fenchylamine, 2 C 10 H 17 NH-COC 3 H 7 , melts at 77.5. 

Benzoyl fenchylamine, 1 C 10 H 17 NH-COC 6 H 5 , 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 
alcohol, and the benzoyl compound is precipitated with dilute 
sodium hydroxide, free benzoic acid being thus removed. It 
melts at 133 to 135. 

Difenchyloxamide, 1 (CONHC 10 H 17 ) 2 , 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. 

Fenchylcarbamide, 1 C 10 H 17 NH-CONH 2 , 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, 1 C 10 H 17 NH-CS-NHC 6 H 5 , 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 . 3 

Difenchylthiocarbamide, 1 CS(NHC 1() H 17 ) 2 , 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 10 H 17 NHCH 3 . 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 

'Wallach, Griepenkerl and Liihrig, Ann. Chem., 269, 358. 
2 Wallach and Binz, Ann. Chem., 276, 317; compare Zeitschr. fiir physik. 
Chem., 12, 723. 

aWallach, 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, v\ D = 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 fenchylamiue hydrochloride is easily soluble (method 
of separation of fenchylamine and methyl fenchylamine). 

Nitroso-methyl fenchylamine, 

/CH S 



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, 1 C 10 H 17 NH-CH 2 C 6 H 5 , 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 hydrochloride and platinochloride form well defined crystals. 

Nitroso-benzyl fenchylamine, 

C 10 H 17 N/ N J 

crystallizes from alcohol or ether in prisms, and melts at 93. 

Benzylidene fenchylamine, 1 C 10 H 17 N = CHC 6 H 5 , 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 combining equal amounts of the levo- and dextro-rotatory 
modifications. 2 

The hydrochloride of the benzylidene derivative is hygroscopic, 
and readily decomposes with formation of benzaldehyde. 

iWallach, Griepenkerl and Liihrig, Ann. Chem., 269, 358. 
"Wallach, Ann. Chem., 272, 105. 



FENCHOLENAMINE. 



351 



Ortho-oxybenzylidene fenchylamine, 1 C 10 H 17 N = CHC 6 H 4 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, 2 C.JEL.N = CHCLH.OH, is 

, 1U 17 64' 

prepared in an analogous manner to the preceding compound by 
condensing p-oxybenzaldehyde with fenchylamine ; it melts at 175. 

Ortho-methoxybenzylidene fenchylamine, 2 C 10 H 17 N = CHC 6 H 4 O- 
CH 3 , 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, CjgH^NO.j, 
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 2 ). 





Melting Point. 


W* 


Wg 


Fenchonoxime 


165 


+52.44 


+ 87.40 






24 89 


38 00 


Formyl fenchylamine 


(114) 


36.56 


66.04 


Acetyl fenchylamine . 


99 


46.62 


90.73 


Propionyl fenchylamine 


123 


53.16 


110.88 


Butyryl f enchy lami ne 


77.5 


53.11 


118.19 


Benzylidene fenchylamine 


42 


+73.14 


+ 175.90 


o-Oxybenzylidene fenchylamine 


94 


+66.59 


+170.77 


-Oxybenzylidene fenchylamine 


175 


+72.00 


+ 184.65 


o-methoxybenzylidene fenchylamine. .. 
p-methoxybenzylidene fenchylamine... 


56 
55 


+59.20 
+78.05 


+ 160.09 
+211.07 



6. FENCHOLENAMINE, C 9 H 15 CH 2 NH 2 . 

A base of the composition, C, H 17 NH 2 , which bears the same 
relation to camphylamine as fenchylamine to bornylamine, was 
obtained by Wallach 3 by the reduction of fenchonoxime anhydride 
(ec-feucholenonitrile), C 9 H 15 CN. This amine was carefully studied 
by Wallach and Jenkel, 4 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 

"Wallach, Griepenkerl and Liihrig, Ann. Chem., 269, 358. 
'Wallach and Binz, Ann. Chem., 276, 317; compare Zeitschr. ftir physik. 
Chem., 12, 723. 

aWallach, Ann. Chem., 263, 138. 

Wallach 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 is then poured into 
water. After acidulating with sulphuric acid, the undecom posed 
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 10 H 21 NO, is obtained (see below). 

Fencholenamine boils at 205 under atmospheric pressure ; it 
readily absorbs carbonic an hydride, and is an unsaturated compound. 

Fencholenamine nitrate, C 1() H 17 NH 2 'HNO 3 , 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 10 H 19 N) 2 'H 2 SO 4 , 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 18 C1NH 2 -HC1, 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 10 H 17 NH-COCH 3 , 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 ln H 17 NHCOC 6 H 5 , 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 fencholenyl alcohol. 

The above-mentioned base, C 10 H 21 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 9 H 17 CH 2 NH 2 . 

Campholamine is prepared by reducing campholonitrile, 1 
C 9 H 17 CN, with sodium in alcoholic solution. (Campholic acid, 
C 9 H 17 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 2 ). 

Campholamine hydrochloride, C 10 H 21 N-HC1, is insoluble in ether, 
and crystallizes from water in silvery laminae. The platino- 
chloride separates from alcohol in yellow plates. 

Campholamine nitrate, C 10 H 21 N-HNO 3 , 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 10 H 19 NH-COC 6 H 5 , 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 10 H 19 NH-CS-NHC 6 H 5 , 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 10 H 19 OH, and a hydro- 
carbon, C 10 H 18 , are formed. Errera 2 terms this hydrocarbon, 
campholene. 

i Errera, Gazz. Chim., 22, I., 205; Ber., 25, 466, Ref. 
'Errera, 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 10 H 15 NH 2 , CONTAINING TWO ETHYLENE 

LINKAGES. 

1. CARVYLAMINES, C 10 H 15 NH 2 . 

By the reduction of carvoxime, C 10 H 14 NOH, with sodium 
amalgam and acetic acid, Goldschmidt 1 obtained a base Avhich he 
called earvylamine, C 10 H 15 NH 2 . The existence of this compound 
was subsequently questioned by Wallach, 2 since he obtained dihy- 
drocarvylamine, C 10 H 17 NH 2 , by reducing carvoxime with sodium 
and alcohol ; Wallach also found dihydrocarvylamine, C 10 H 17 NH 2 , 
to be identical with the base, prepared by Leuckart and Bach 3 
and by Lampe 4 on the treatment of carvone with ammonium 
formate, which had previously been called " carvylamine," 
C 10 H 15 NH 2 . 

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 5 has sufficiently proved the existence of his carvyl- 
amine, C 10 H 15 NH 2 , and has shown it to be quite different from 
dihydrocarvylamine. 

According to Goldschmidt, 5 when an alcoholic solution of dextro- 
carvoxime is reduced with sodium amalgam, or zinc dust, and 
acetic acid, two optically active, isomeric bases are formed, which 
are designated as a-d- and p'-d-carvylamine, C 10 H 15 NH 2 . Levo-car- 
voxime likewise gives rise to two bases a-1- and /9-1-carvylamine, 
whose derivatives have the same melting point, solubility, etc., 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 /9-carvylamines, have been separated 
in the form of their benzoyl derivatives, so that altogether six 
isomeric benzoyl carvylamines have been isolated. 

iH. Goldschmidt, Ber., 19, 3232; 20, 486; 26, 2084. 

2 Wallach, Ann. Chem., 275, 120. 

3 Leuckart and Bach, Ber., 20, 105. 
*Lampe, Inaug. Diss., Gottingen, 1889. 

s Goldschmidt and Fischer, Ber., 30, 2069. 

354 



/3-D-CARVYL PHENYLCARBAMIDE. 355 

The reduction of carvoxime is accomplished as follows. An 
alcoholic solution of d-carvoxime is heated with zinc 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 zinc 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 
/9-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 hydro-chloride, C 10 H 15 NH 2 -HC1, crytallizes from 
absolute alcohol in fine needles, melts with decomposition at 180, 
and is readily soluble in water. 

a-d-Carvyl phenylcarbamide, C 10 H 15 NH-CONHC 6 H 6 , can not be 
obtained entirely free of the /9-derivative ; it is crystalline, and 
melts at 187 to 191. 

Benzoyl-a-d-carvylamine, C^H^NH-COCgH,, is produced by 
treating an aqueous solution of the a-d-nitrate with alkali and 
benzoyl chloride ; it usually contains some of the ^-derivative as 
an impurity, but after repeated crystallization from methyl alco- 
hol, it is freed from most of the /3-compound. It crystallizes 
from methyl alcohol in long, white needles, and melts at 169 ; 
it is levorotatory, [a] D = 91.9. 

a-d-Carvyl carbamide, C 10 H 15 NH-CONH 2 , 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 1 87. 

The /3-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. 

/3-d-Carvyl phenylcarbamide, C 10 H 15 NH-CONHC g H 5 , crystallizes 
in small, white needles, and melts at 138. 



356 THE TERPENES. 

Benzoyl-/3-d-carvylamine, C 10 H 15 NH'COC 6 H 5 , is prepared from 
the /3-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] I ,= + 176.6. 

When 1-carvoxime is reduced in alcoholic solution with zinc 
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-1-carvylamine, C 10 H 15 NH-COC 6 H 5 , crystallizes from 
methyl alcohol in long, white needles, melts at 169, and is dex- 
trorotatory, [d] D = +92.6. 

Benzoyl-/3-l-carvylamine, C 10 H 15 NH-COC 6 H 5 , crystallizes from 
methyl alcohol, melts at 103, and is levorotatory, [a] Z) = 
- 175.4. 

Racemic benzoyl-a-carvylamine, (C 10 H 15 NH>COC 6 H 5 ) 2 , is ob- 
tained by crystallizing together equal weights of the a-d- and a-1- 
derivatives from methyl alcohol ; it forms fine, white needles, and 
melts at 141. 

Racemic benzoyl-/9-carvylamine, (C 10 H 15 NH-COC 6 H 5 ) 2 , is pro- 
duced from the two /^-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 10 H 17 NH 2 , CONTAINING ONE ETHYLENE 

LINKAGE. 

1. DIHYDROCARVYLAMINE, C 10 H 17 NH 2 . 

By the treatment of carvone with ammonium formate, Leuckart 
and Bach, 1 and Lampe 2 obtained a base which they called " carvyl- 
amine," C ]0 H 15 NH 2 . Wallach 3 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 10 H 15 NH 2 , but that it 
had the constitution, C 10 H 17 NH 2 , dihydrocarvylamine. Wallach has 

' Leuckart and Bach, Ber., 20, 105. 

2 Lampe, Inaug. Diss., Gottingen, 1889. 

3 Wallach, Ann. Chem., 275, 120; Ber., 24, 3984. 



DIHYDROCARVYLAMINE HYDEOCHLORIDE. 357 

also regarded dihydrocarvylamine as chemically identical with 
Goldschmidt's carvylamine, C 10 H 15 NH 2 , but more recent publi- 
cations l 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 2 ). 

In order to prepare the base by the reduction of carvoxime, 2 
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, n^ = 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 10 H 17 NH 2 -HC1, 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 : 



C 10 H 1T NH 2 HCl = NH i C14-C, H ul ; 
CioH 16 = H, + C 10 H U . 

1 Goldschmidt and Fischer, Ber., 80, 2069. 

2 Wallach, Ann. Chem., 275, 120; Ber., 24, 3984. 



358 THE TERPENES. 

Dihydrocarvylamine sulphate crystallizes in characteristic, lus- 
trous leaflets, and is sparingly soluble. The oxalate 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 17 NHCOCH 3 , 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 10 H 17 NH'COC 6 H 5 , crystallizes 
from methyl alcohol in needles, and melts at 181 to 182. 

Dihydrocarvyl phenylcarbamide, C 10 H 17 NH-CO-NHC 6 H 5 , melts 
at 191. 

Dihydrocarvyl phenylthiocarbamide, C 10 H 17 NH-CS-NHC 6 H 5 , 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, 1 C 10 H 16 (NH 2 ) 2 , 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 auriehloride crystallizes in long needles. 
The oxalate melts at 135 to 140, the dibenzoyl derivative at 
275 to 276, the diphenykarbamide at 214 to 216, and the 
diphenylthiocarbamide at 179 to 180. 

On the dry distillation of dihydrocarvyldiamine, a hydro- 
carbon, C 10 H 14 , isomeric with cymene, is formed ; it is an unsatu- 
rated compound, and boils at 170 to 175. 

2. CARYLAMINE, C 10 H 17 NH 2 . 

Carylamine is formed when one part of the oily caronoxime, 
C 10 H 16 NOH, is dissolved in twenty-one parts of alcohol and re- 
duced with three parts of sodium (Baeyer 2 ). 

'Harries and Mayrhofer, Ber., 82, 1345. 
* Bayer, Ber., 27, 3486. 



DTHYDROEUCAEVYLAMINE. 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 ]0 H 17 NH 2 -HC1, is obtained by sat- 
urating an ethereal solution of the base with hydrochloric acid 
gas. On evaporation of the ther, 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 vestrylamine hydrochloride. The aqueous solution of 
carylamine hydrochloride gives no precipitate with platinic 
chloride. 

Benzoyl carylamine, C 10 H 17 NH>COC 6 H 5 , is prepared by Schot- 
ten-Baumann's method, and crystallizes from ethyl acetate in 
large, flat prisms, which melt at 123. 

Caryl phenylthiocarbamide, C 10 H 17 NH-CS-NHC 6 H 5 , melts at 
145 to 146. 

3. VESTRYLAMINE, C 10 H, 7 NH 2 . 

Carylamiue is readily transformed into the isomeric, unsaturated 
vestrylamine l by saturating an alcoholic solution of carylamiue 
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 
crystals 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 10 H 1T NH 2 -HC1 = C 10 H 16 + NH.C1. 

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 10 H 17 NH 2 . 

Dihydroeucarvylamine was obtained by Baeyer 2 in the reduc- 
tion of eucarvoxime and of dihydroeucarvoxime hydriodide with 

i Bayer, Ber., 27, 3486. 

"Bayer, 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. 1 

Dihydroeucarvylamine hydrochloride is crystalline and rather 
sparingly soluble. The platinochloride is also crystalline and 
difficultly soluble. 

Benzoyl dihydroeucarvylamine, C 10 H 17 NH-COC 6 H 5 , 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, 1 C 10 H 17 NH-CO-NHC fi H 5 , 
melts at 142, and the phenylthiocarbamide, C 10 H 17 NH-CS-NH- 
C 6 H 5 , crystallizes from methyl alcohol in transparent plates, and 
melts at 120 to 121. 

5. THUJYLAMINE (TANACETYLAMINE), C 10 H 17 NH 2 . 

Tanacetylarnine, C 10 H 17 NH 2 , is formed when ten parts of 
tanacetoxime (m. p. 51.5) are reduced with twenty-five parts of 
sodium and fifty parts of alcohol (Semmler 2 ). The same base, 
designated by Wallach as thujylamine, is obtained by reducing 
thujonoxime (m. p. 54) with alcohol and sodium (Wallach 3 ). 

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, n^ = 1.462, at 0. 

According to Wallach, it boils at 195, has a specific gravity 
of 0.8735 and refractive index, n^ = 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 10 H 16 , 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, n^, = 1.476, at 20 (Semmler). According to Tschugaeff, 4 
the dry distillation of thujylamine hydrochloride gives isothujene 
and not thujene. It contains two ethylene linkages. 

1 Wallach, Ann. Chem., 305, 223. 
Semmler, Ber., 25, 3345. 
Wallach, Ann. Chem., 286, 96. 
* Tschugaeff, Ber., 34, 2270. 



ISOMERIC THUJYLAMINE. 361 

Thujyl phenylcarbamide, C 10 H 1? NH CO NHC 6 H 5 , results by 
the interaction of thujylamine and phenylcarbimide ; it crystal- 
lizes in prisms, and melts at 120 (Wallach). 

Dimethylthujylamine, 1 C 10 H ]7 N(CH 3 ) 2 , 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 
[]^= -f 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, 1 C 10 H 17 N(CH 3 ) 3 T, 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, [a]^= +42.61, and is only sparingly 
soluble in cold water. 

Thujyl trimethyl ammonium hydroxide, 1 C 10 H 17 N(CH 3 ) 3 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 10 H 16 (b. p. 151 to 153, sp. 
gr. 0.8263 at 20/4, Dj) = 1.45022 at 20, and [] jD =- 
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 10 H 17 NH 2 , 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 10 H ir NH 2 , which boils 
at 193, and at 20 has the specific gravity 0.875 and refractive 
index, n^, = 1.46256 (Wallach 2 ). 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. 

iTschugaeff, Ber., 3 4, 2276. 
iWallach, Ann. Chem., 286, 96. 



362 THE TERPENES. 

Wallach l 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 10 H 16 ; this hydrocarbon boils at 172 to 175, has the specific 
gravity 0.840 and refractive index, n^ = 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 10 H 17 NH 2 . 

Isothujylamine is produced when isothujonoxime (m. p. 119 to 
120) is reduced with sodium and alcohol (Wallach 2 ). 

It boils at 200 to 201, has a specific gravity of 0.865 and a 
refractive index, n^ = 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, n^, = 
1.47145, at 22. 

Isothujylcarbamide, C 10 H 17 NH < CO-NH 2 , is prepared by the in- 
teraction of isothujylamine hydrochloride and potassium isocya- 
nate ; it melts at 158 to 159. 

Isothujyl phenylcarbamide, C 10 H 17 NH-CO'NHC 6 H 5 , forms small 
needles, which are readily soluble in alcohol, and melt at 178. 

Isothujyl phenylthiocarbamide, C 10 H 17 NH-CS-NHC 6 H 5 , crystal- 
lizes in needles, dissolves sparingly in methyl alcohol, and melts 
at 152 to 153. 

7. PULEGYLAMINE, C 10 H 17 NH 2 . 

Pulegylamine is obtained by reducing the normal pulegonoxime, 
C ]0 H 16 NOH, in an alcoholic solution with sodium. It is a crys- 
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. 

iWallach, Ann. Chem., 272, 109. 
*Wallach, Ann. Chem., 286, 97. 



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 1 ). 

Beckmann and Pleissner 2 obtained a base, C 10 H 19 ON, which 
they termed pulegonamine, by the action of hydriodic acid on the 
u hydrated pulegonoxime," C 10 H 19 NO 2 . 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 10 H 19 NOHC1, demands. 

Pulegonamine phenylthiocarbamide, 

,NC 10 H 18 

\NHC.H 6 

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 10 H 18 ON-COC 6 H 5 , 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. 

Methyl pulegonamine, C 10 H 18 ON-CH 3 , is produced by boiling 
pulegonamine with methyl iodide and decomposing the reaction- 
product with potash ; it is a light yellow oil, having a penetrating, 

i Wallach, Ann. Chem., 289, 347. 

2 Beckmann and Pleissner, Ann. Chem., 262, 13. 



364 



THE TERPENES. 



fish-like smell. Its platinochhride, (C n H 22 NOCl) 2 PtCl 4 , 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 10 H 19 NH 2 , WITHOUT AN ETHYLENE LINKAGE. 

1. CARVOMENTHYLAMINE (TETRAHYDEOCARVYLAMINE), 

C 19 H 19 NH 2 . 

(Amido-2-hexahydrocymene.') 

When the oxime of tetrahydrocarvoue (carvomenthone), 
C 10 H 18 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 l regards this compound as 
having the constitution of an amido-2-hexahydrocymene ; it may 
be designated as carvomenthylamine or tetrahydrocarvylamine : 




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 2 ). 

1 Wallach, Ann. Chem., 277, 137. 

"Wallach and Herbig, Ann. Chem., 287, 371. 



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. 

Carvomentliylamine hydrochloride, C 10 H 19 NH 2 HC1, 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 10 H 19 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 10 H 19 NHCOCH 3 , 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 10 H 19 NH-CS'NHC 6 H 5 , 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 10 H 19 NH-CONH 2 , 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 203. 

Carvomenthyl phenylcarbamide, 1 C 10 H 19 NH-CO-NHC 6 H 5 . The 
inactive modification melts at 145 to 150, and the active de- 
rivatives at 185 to 186. 

Optically active carvomenthol 1 is formed when the salts of op- 
tically active carvomenthylamine are treated with a solution of 
sodium nitrite. 

2. MENTHYLAMINE, C 10 H ]g NH 2 . 

Menthylamine was first prepared by Moriya 2 by the reduction 
of a nitre-compound, obtained by the action of strong nitric acid 

JWallach and Herbig, Ann. Chem., 287, 371. 
* Moriya, Journ. Chem. Soc., 1881, 77. 



366 THE TERPENES. 

on menthol, with tin and sulphuric acid; the properties of this 
amine were very incompletely described. Andres and Andreef l 
subsequently showed that a base having a strong levorotatory 
power was formed by reducing levo-menthonoxime with sodium 
and alcohol. Wallach and Kuthe 2 then obtained the same re- 
sults, although Wallach 3 had previously shown that a base, 
C 10 H 19 NH 2 , 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 2 , and a third asym- 
metric carbon atom is introduced, as shown by the formulas in 
which the asymmetric atoms are represented by heavy type : 





C 3 H T C 8 H 7 

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 : 
(- -)C 10 H 18 and (-, -)C 10 H 18 :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 : 

( ) > )Qo H 19 NH 2 5 

or, the third asymmetric atom may act in the opposite direction 

'Andres and Andreef, Ber., 25, 618; 24, 560, Ref. 

2 Wallach and Kuthe, Ann. Chem., 276, 296; compare Ber., 25, 3313. 

s Wallach, Ber., 2J h 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 : 

(-, -, +)C 10 H 1 ,NH J . 

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, 1 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, 1-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 1-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 ds- and rans-isomerism ; 
1-menthylamine and 1-menthol are to be regarded as trans-com- 
pounds, and the dextro-isomers as cts-derivatives. The following 
formulas will illustrate this. 

PH, 

R 




H 2 C 2 

H 2 C CH-NH, 



H C 3 H 7 H 7 ( H 

Trans-(Z)-Menthylamine. C r is-(d)-Menthylamine. 

If, in the above formulas, the NH 2 group be replaced by the 
(OH) group, the corresponding menthols result, and* it will be 
Negoworoff , Ber., 25, 162e.; compare Ber., 25, 620. 



368 THE TERPEXES. 

observed that menthene can be formed more readily by the elimi- 
nation of water from cis- menthol than from rans-menthol. 

(a) l-(TRANS-) MENTHYLAMINE. 

1-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 amiue 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, n^ = 1.46058, at 20; [a]^ = - 38.07. 

1-Menthylamine hydrochloride, C 10 H 19 NH 2 - HC1, 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 10 H 19 NH 2 - HBr, is more spar- 
ingly soluble in water than the hydrochloride, and crystallizes 
from water in needles. The hydriodide is more difficultly soluble 
than the hydrobromide. 

1-Menthylamine nitrite, C 10 H 19 NH 2 ' HNO 2 , is prepared from 
molecular proportions of the hydrochloride of the base and sodium 
nitrite ; on heating, it is converted into menthol, 

C 10 H 19 NH 2 -HN0 2 = C 10 H 19 OH + H 2 O + N 2 . 

1-Formyl menthylamine, C 10 H 19 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 10 H 19 NH-COCH 3 , is obtained by the 
addition of the theoretical quantity of acetic anhydride to a solu- 
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. 




L-MENTHYL TRIMETHYL AMMONIUM IODIDE. 369 

1-Propionyl menthylamine, C 10 H 19 NH-COC 2 H 5 , 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 10 H 19 NH-COC 3 H 7 , 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 10 H 19 -NH-CONH 2 , is obtained as an oil by 
the action of potassium isocyanate on 1-methylamine hydrochloride ; 
it solidifies after standing some time, and melts at 134 to 136. 

1-Menthyl phenylcarbamide, C 10 H 19 NH-CONHC 6 H 5 , results by 
the action of carbanile on the free base ; it crystallizes from alcohol, 
and melts at 140 to 141. 

1-Menthyl phenylthiocarbamide, C 10 H 19 NH-CS-NHC 6 H 5 , 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 10 H 19 N==CHC 6 H 5 , is obtained by 
the action of benzaldehyde on menthylamine in a methyl alcoholic 
solution; it is crystallized from methyl alcohol, and melts at 69 
to 70. 

1-Ortho-oxybenzylidene menthylamine, C 10 H 19 N = CH'C 6 H 4 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 10 H 19 N(NO) CH 3 , is a yellow oil, 
boiling at 145 to 146 under 18 to 20 mm. pressure. 

1-Menthyl ethylnitrosamine, C 10 H 19 N(NO)- C 2 H 5 , crystallizes from 
dilute methyl alcohol in colorless needles, melts at 52 to 53, 
and boils at 155 to 1-56 (22 mm.). 

1-Menthyl propylnitrosamine, C 10 H 19 N(NO)C 3 H 7 , boils at 159 
to 161 (20 mm.). 

1-Menthyl isobutylnitrosamine, C 10 H 19 N(NO)C 4 H 9 , crystallizes in 
white needles, melts at 52 to 53, and boils at 160 to 161. 

1-Menthyl trimethyl ammonium iodide, -C IO H 19 N(CH 3 ) S I, crystal- 
lizes from water in large, colorless crystals, and melts at 190. 

24 

I 



370 THE TERPENES. 

Its alcoholic solution absorbs one molecule of iodine, forming a 
triiodide, C 10 H I9 N(CH 3 ) 3 I 3 , melting at 117 to 118. 

1-Menthyl trimethyl ammonium hydroxide, C 10 H 19 N(CH 3 ) 3 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 10 H, 8 ; the latter boils at 170 to 
171, has the specific rotatory power, [a]^ = -f 89.307, and 
does not yield a uitrosochloride. 

(6) 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 1- and 
d-menthylamines is obtained. d-Forrnyl menthylamine is char- 
acterized by its great power of crystallization, and is more spar- 
ingly soluble than the isomeric 1-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-formyl 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, 1-formyl menthyl- 
amine and menthol are formed by the action of ammonium for- 
mate on levo-menthone ; the presence of the 1-base may be proved 
by its transformation into 1-menthylamine hydrochloride, which is 
insoluble in ether. 

Larger quantities of the d-base may be conveniently prepared 
by the following method. 1 In a 250 cc. round-bottom flask hav- 
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 

'Wallach and Werner, Ann. Chem., 300, 283. 




D-BUTYRYL MENTHYLAMIXE. 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 crystalliza- 
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 
1-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, n^, = 1.45940, and the specific rota- 
tory power, [] Z) = -f 14.71 ; in other properties the two men- 
thylamines are similar, but their derivatives diifer very decidedly 
in melting point, solubility, etc. 

d-Menthylamine hydrochloride, C 10 H 19 NH,-HC1, 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 10 H )9 NH 2 -HBr, is sparingly sol- 
uble in ether, and crystallizes from water in fine, small needles, 
which melt at 225. 

d-Menthylamine hydriodide, C 10 H 19 NH 2 'HI, is slightly soluble in 
water and ether, and melts at 270 with decomposition. 

d-Formyl menthylamine, C 10 H 19 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 methyl 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 10 H ]g NH-COCH 3 , is obtained in the 
same manner as the corresponding 1-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 10 H 19 NH COC 2 H 5 , melts at 151. 

d-Butyryl menthylamine, C 10 H 19 NH COC 3 H 7 , melts at 105 to 
106, dissolves readily in methyl alcohol, sparingly in ethyl ace- 
tate, and very difficultly in ether and ligroine. 



372 THE TERPENES. 

d-Menthyl carbamide, C 10 H, 9 * NH CONH 2 , crystallizes from 
dilute alcohol, and melts 155 to 156. 

d-Menthyl phenylcarbamide, C 10 H 19 NH-CONHC 6 H 5 , crystallizes 
from alcohol in fine needles, and melts at 177 to 178. 

d-Menthyl phenylthiocarbamide, C 10 H 19 NH-CS NHC 6 H 5 , is pre- 
pared like the 1-derivative ; it separates from methyl alcohol in 
small crystals, having a diamond-like luster, and melts at 178 
to 179. 

d-Menthyl allylthiocarbamide, C 10 H 19 NH-CS-NHC 3 H 5 , 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-Menthyl trimethyl ammonium iodide, C 10 H 19 N(CH 3 ) 3 I, crys- 
tallizes from hot water, and melts at 160 to 161. 

d-Manthyl trimethyl ammonium hydroxide, C, H 19 N(CH 3 ) 3 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 19 N = CHC g H 5 , 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 10 H 19 N = CHC 6 H 4 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 
jV]^ = -(- 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 1-menthone semicarbazone. 

1-Menthylamine is not converted into d-menthylamine at high 
temperatures, and the derivatives of the levo-base can not be 
transformed into those of the dextrorotatory amine. 

An investigation regarding the optical behavior of 1- and 
d-menthylamines, and of their salts and derivatives has been 



carried out by Wallach and Binz. 1 The following table presents 
the most important values obtained for the specific and molecular 
rotatory powers of these compounds. 





Solvent. 


[]/>. 


WD. 


/-Meat h vlamine 




38 07 


58 90 


hydrochloride 


Water 


35 66 


68 15 


hydrobromide 


it 


29.32 


69 04 


hydriodide 





24 72 


69 77 










d-Menthylamine 




+14.71 


+22 76 


h vdrochloride 


Water 


+17.24 


+32 94 


hydrobromide 





+13.83 


+32 56 


hydriodide 





+ 11.79 


+33 28 


hydrochloride 


Ether 


+ 8 34 


+15 94 


hydrobrornide 


ii 


+ 5.26 


+12.38 














83 37 


152 27 


i-Acetyl 




81.81 


160.84 


2-Propionyl 




76.53 


161.15 


Z-Butyryl 




72.10 


161.90 


d-Formyl 


Chloroform 


+54.03 


+98.68 


d-A cety 1 




+50.57 


+99.42 


cf-Propionyl 




+45.14 


+95.05 


d-Butyryl 




+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 10 H 19 NH 2 . 



According to Baeyer, 2 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. 




C 3 H 7 
Tertiary carvomenthylamine. 

1 Wallach arid Binz, Ann. Chem., 276, 317; compare Zeitschr. fUr physik. 
Chem., 12, 723. 

2 Baeyer, 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, n H 1Q NH 9 . 

iu i y J 

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, 1 this amine has the consti- 
tution : 




Tertiary menthylamine hydrochloride, C 10 H 19 NH 2 'HC1, 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, C 10 H 15 NH 2 . 

The so-called nitrophellandrene, C 10 H 15 NO 2 , obtained by Pesci 
by the action of ammonia on phellandrene nitrosite, may be con- 
verted into amidophellandrene by the following method (Pesci 2 ). 

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 

1 Baeyer, Ber., 26, 2270 and 2562. 

2 Pesci, Gazz. Chim., 16, L, 228; Jahresb. Chem., 1884, 547. 



DIAMIDOPHELLANDRENE. 375 

of zinc 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 10 H 15 NH 2 ) 2 -H 2 SO 4 , is rather spar- 
ingly soluble in cold water. The hydrochloride is crystalline, 
and easily soluble in alcohol and water. The platinochloride, 
(C 10 H 15 NH 2 -HCl) 2 PtCl 4 , 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 10 H 15 NO 2 , 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 10 H 16 (NH 2 ) 2 . 

A diamine, C 10 H 16 (NH 2 ) 2 , was obtained by Pesci 1 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 zinc 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- 

> Pesci, Gazz. Chim., 16, I., 229; Jahresb. Chem., 1885, 698. 



376 



THE TERPENES. 



composition. It is readily soluble in water and alcohol, more 
sparingly in ether, chloroform and ligroine. 

The hydrochloride is crystalline but hygroscopic ; it yields a 
platinochloride, C 10 H 16 (NH 2 ) 2 '2HCl-PtCl 4 , which crystallizes in 
monoclinic prisms. 

The sulphate, acetate, nitrate and tartrate of phellaudrene dia- 
mine are hygroscopic. 



OLEFINIC MEMBERS OF THE TERPENE SERIES. 

A. HYDROCARBONS. 

1. MYRCENE, C 10 H 16 . 

Bay oil contains eugenol, methyl eugenol, chavicol, methyl 
chavicol, geranial and two hydrocarbons, C JO H 16 . Mittmann * 
regarded these hydrocarbons as pinene and another terpene, prob- 
ably dipentene ; Power and Kleber, 2 however, proved that bay 
oil contains levorotatory phellandrene and a hydrocarbon, C 10 H 16 , 
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. 3 

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, n^ = 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 4 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 10 H 17 OH. The presence of linalool is proved 

i Mittmann, Arch. Pharm., 1889, 529. 

zpharm. Rund., New York, 1895, No. 13; Semi- Annual Report, Schim- 
mel & Co., April, 1895, 11. 

Tower and Kleber, Pharm. Review, 1896. 
'German Patent, No. 80,711. 

377 



378 THE TERPENES. 

by its conversion into the aldehyde geranial (citral), C 10 H 16 O, by 
careful oxidation, and by the characterization of the latter com- 
pound in the formation of the crystalline geranial-/?-naphthocin- 
chonic acid (see geranial, page 399). Since myrcene may be con- 
verted into linalool, C 10 H 17 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, l however, the alcohol, C 10 H 17 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 10 H 17 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 10 H 17 OOCCH 3 , 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 10 H 16 O (not geranial), boiling 
at 110 (10 mm.). This aldehyde forms an oxime, C 10 H 16 '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 3 . 

>C=CH CH, CH=C CH=CH 2 . 
CH/ | 

CH 3 
Myrcene. 

CH 3 , 

>C=CH CH 2 CH a C(OH) CH=CH 2 . 
CH/ ! 

CH 3 
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). 

!P. Barbier, Compt. rend., 132, 1048. 



ANHYDROGERANIOL. 379 

Dihydromyrcene, 1 C 10 H 18 , 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, n^ = 1.4501. On oxi- 
dation with permanganate, it yields laevulinic acid and a keto- 
gfycol, C 8 H 16 O 3 , which, on oxidation with chromic acid, gives rise 
to a diketone, C 7 H 12 O 2 . 

Cyclodihydromyrcene, 1 C 10 H 18 , 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, 
n^, = 1.462. It unites with bromine, forming a dibromide (sp. gr. 
1.524), and when oxidized it yields a ketonic acid, C 10 H 18 O 3 . 

It should also be mentioned that the chemists of Schimmel & 
Co. 2 have isolated a hydrocarbon, C 10 H 16 , 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, n^, = 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 10 H 16 . 

Anhydrogeraniol was the first known representative of the class 
of olefinic terpenes. It is formed by heating geraniol, C 10 H 17 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 10 H 16 ; it has a peculiar 
smell, a specific gravity 0.8232 and refractive power, n^ = 1.4835, 
at 20. It yields a hydrocarbon, C 10 H 22 , by reduction, and unites 
with bromine, forming the compound, C 10 H 16 Br 6 (Semmler 3 ). 

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, 3 Semmler mentions that 
similar olefinic terpenes are obtained from linalool and coriandrol 
by treatment with acid potassium sulphate as above described. 

i Semmler, Ber., 34, 3122. 

2Schimmel & Co., Semi-Annual Report, April-May, 1901, 12. 

Semmler, Ber., 24, 682. 



380 THE TERPENES. 

3. OLEFINIO TERPENES IN OIL OF HOPS AND OIL OF 
ORIGANUM. 

Investigations of Chapman l on the oil of hops, and of Gilde- 
meister 2 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 10 H 18 . 

Linalolene is obtained by reducing linalool with sodium and 
alcohol, or better by heating equal weights of linalool and zinc 
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, n^, = 1.455, at 20 
(Semmler 3 ). 

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, n^, = 
1.4602, at 17. Semmler considers this isomeride as a hydro- 
benzene derivative, and calls it cyclolinalolene. 

5. HYDROCARBON, C 10 H 18 , OBTAINED FROM MENTHONYL- 

AMINE. 

When menthonylamine is treated with nitrous acid in the prep- 
aration of menthocitronellol, C 10 H 19 OH, a by-product is formed 
which contains a hydrocarbon, C 10 H ]8 . It boils at 153 to 156, 
has the specific gravity of 0.7545 at 15, and a refractive power, 
n^= 1.4345 (Wallach 4 ). 

1 Chapman, Jour. Chem. Soc., 1894, 1, 54; Ber., 28, 303, Ref. 
'Gildemeister, Arch. Pharm., 233, 182. 
3 Semmler, Ber., 27, 2520. 
'Wallach, Ann. Chem., 278, 317. 



LINALOOL. 381 

B. OXYGENATED COMPOUNDS. 

(a) ALCOHOLS. 
1. LINALOOL, C 10 H 17 OH. 

Morin 1 showed that the oil of linaloe contains an alcohol, 
C 10 H 17 OH, which Semmler 2 in the year 1891 identified as an 
aliphatic terpene alcohol ; he called it linalool. In the following 
year Barbier 3 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. 4 

Linalool is very widely distributed in nature. Simultaneous 
with Semmler and Tiemann, 5 Bertram and Walbaum 6 found 
linalool and linaloyl acetate in the oil of bergamot. The alcohols, 
C 10 H 17 OH, which Semmler and Tiemann s called " aurantiol " and 
" 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 6 ). In a subsequent publication, Tiemann and Semm- 
ler 7 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 liualool. 
According to Reychler, linalool is also found in oil of ylang- 
ylang 8 and in oil of cananga 9 ; according to Gildemeister, 10 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 sdarea L.). 

1-Linalool, partly free, partly as ester, forms a constituent of 
Palermo lemon oil, spike oil, thyme oil, 11 Russian spearmint oil, 
German 12 and French 13 basilicum oil, and sassafras leaf oil. 

'Morin, Ann. Chim.,Phys. [5], 25, 427. 

* Semmler, Ber., 24, 207. 

a Barbier, Compt. rend., 114, 674; Ber., 25, 463, Ref. 

*Barbier and Bouveault, Compt. rend., 121, 168. 

5 Semmler and Tiemann, Ber., 25, 1180. 

6 Bertram and Walbaum, Journ. pr. Chem. [2], 45, 590. 

'Tiemann and Semmler, Ber., 26, 2708. 

sReychler, Bull. Soc. Chim. [3], 11, 407 and 576; Ber., 27, 751, Ref.; 
28, 151, Ref. 

9Reychler, Bull. Soc. Chim. [3], 11, 1045. 
'0 Gildemeister, Arch. Pharm., 233, 174. 

"Labbe, Bull. Soc. Chim., 19 [III.], 1009; Schimmel & Co., Semi-Annual 
Report, Oct., 1894, 57. 

^Bertram and Walbaum, Arch. Pharm., 235, 176. 
13 Dupont and Guerlain, Compt. rend., 124, 3 0- 



382 



THE TEEPENES. 



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. These variations are 
rendered apparent by the following table. 



LINALOOL OBTAINED FROM, 





Lavender 
Oil 
(Bertram 
and 
Walbaum). 1 


Bergamot 
Oil 
(Bertram 
and 
Walbaum). 1 


Lin aloe 
Oil 
(Bertram 
and 
Walbaum). 1 


Linaloe 
Oil 
(Semmler). 8 


Oil 

of Limes 
(Gilde- 
meister). 3 


Oil of 
Origanum 
(Gilde- 
meister).* 


Boiling point. 

Specific gravity. 

Refractive 
index, n/>. 
Angle of rotation 
(100mm.). 


197 to 
199 

0.87 25 at 
15 
1.4640 at 
20 
i f) 0f ?v 


197 to 
199 

0.8720 at 
15 
1.4629 at 
18 

1 CO 


197 to 
200 

0.8770 at 
15 
1.4630 at 
20 

00 


195 to 
199 

0.8702 at 
20 
1.4695 at 
20 


198 to 
199 
under 
760 mm. 
0.870 at 
15 
1.4668 at 
20 
1737' 
at 15 


197. 8 to 
199 
under 
752mm. 
0.8704 at 
15 
1.4633 at 
20 
1556' 
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 10 H 16 O, which is characterized by its 
transformation into cymene, and by the formation of the crystal- 
line geranial (citral)-/3-naphthocinchonic acid, melting at 198 to 
199. 

All alcohols of the formula, C 10 H 17 OH, having the properties 
given in the above table, are termed linalool if they are optically 



'Bertram and Walbaum, Journ. pr. Chem. [2], 
*Semmler, Ber., 24, 207. 
'Gildemeister, Arch. Pharm., 233, 174. 



590. 



LIN ALGOL. 383 

levorotatory, and yield geranial on oxidation. If this definition 
of linalool be accepted, then an optically dextrorotatory alcohol, 
which Seramler l called " coriandrol" must be designated as dex- 
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, n^, = 1.4652, at 20, 
and is converted into geranial by oxidation ; its optical rotation 
is reported as [a\ D = + 13 19' and + 15 I/. 

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 2 
represent the transformation of linalool into geraniol by the fol- 
lowing formulas : 

CH, C =CH CH 2 CH 2 C (OH) CH = CH 2 
CHj CHj 

Linalool (dimethyl-2-6-octadiene-2-7-ol-6 ). 

CH S C = CH CH, CH 2 C = CH CH S OH. 

CH, CH S 

Geraniol (dimethyl-2-6-octadiene-2-6-ol-8). 

According to more recent investigations by Barbier, 3 this for- 
mula for linalool represents the constitution of myrcenol, and 

' Semmler, Ber., 24, 206; compare Kawalier, Jahresb. Chem., 1852, 624, 
and Grosser, Ber., 14, 2485. 

2 Tiemann and Semmler, Ber., 28, 2126. 
>Barbier, 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 : 



CH 3 C=CH CH,CH 2 -C=CH CH,OH. 

CH 3 CH 3 

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 10 H 18 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, 1 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 sodium 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. 2 Another method of preparing inactive linalool consists in 
treating geraniol with hydrochloric acid, and saponifying the re- 
sultant, isomeric chlorides, C 10 H 17 C1, with alcoholic potash ; some 
geraniol is regenerated, and about fifty per cent, of inactive 
linalool is obtained (Tiemann 3 ). According to Stephan, 4 a third 
method of converting geraniol into inactive linalool consists in 

'Tiemann and Kriiger, Ber., 29, 901; Tiemann, Ber., 81, 837. 
zSchimmel & Co., Semi-Annual Report, April, 1898, 27. 
sTiemann, Ber., 31, 832. 
Stephan, 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 l ; 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 zinc dust at 220 or 230, 
it is converted into linalolene, C 10 H 18 (Semmler). By the action 
of hydrochloric acid on linalool, water is eliminated, and a mixture 
of liquid chlorides, C 10 H 18 C1 2 , results; they decompose when dis- 
tilled in vacuum (Bertram and Walbaum). 

According to Barbier, 2 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 10 H 16 , 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 3 ). 

When 1-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 3 ). 

Hydrogen peroxide converts linalool into a crystalline com- 
pound, melting at 110 to 111; this substance has been shown to 

iSchimmel & Co., Semi- Annual Report, Oct., 1896, 85; compare with 
Charabot, Bull. Soc. Chim., 21, 549. 

* Barbier and Bouveault, Bull. Soc. Chim., 15 [III.], 594. 
3 Stephan, Journ. pr. Chern., 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. 1 

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, etc. 

Tiemann and Semmler 2 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,) Z = CH CH, CH 2 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 10 H 17 C1 and C 10 H 17 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 10 H 16 O, carbonic anhydride, acetic acid and a gelatinous acid, 
having the constitution C g H 10 O 4 (Grosser 3 ). 

Linaloyl acetate, C 10 H 17 OCOCH 3 , 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 4 ). 

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 terpeues 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 

'Tiemann and Semmler, Ber., 28, 2137. 
^Tiemann and Semmler, Ber., 28, 2126. 
sGrosser, Ber., lit, 2494 and 2497. 

4 Power and Kleber, Pharm. Rundsch, 1895, No. 13; A. Hesse, Journ. pr. 
Chem., 64 [II.], 245. 



GERANIOL. 387 

specific gravity 0.912 at 15 ; [] = - 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-Jinaloyl 
acetate is obtained ; this yields dextro-linalool when saponified 
(Gildemeister *). 

Linaloyl propionate, C 10 H 17 OCOC 2 H 5 , 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 10 H 17 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. 2 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 for a long time ; the resultant alco- 
hol, having a rose-like odor, was thought to be different from 
geraniol, and was called " licarhodol." Bouchardat 3 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 4 by the isolation of the cal- 
cium chloride compound of geraniol from Barbier's licarhodol. 

"Gildemeister, 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. 

* Barbier, Compt. . rend., 116, 1200; Ber., 16, 490, Ref. 

sBouchardat, Compt. rend., 116, 1253; compare Barbier, Compt. rend., 
Ill, 122. 

* Bertram and Gildemeister, Journ. pr. Chem. [2], 49, 185; compare 
Stephan, Journ. pr. Chem. [2], 58, 109; Schimmel & Co., Semi-Annual Re- 
port, April, 1898, 33. 



388 THE TERPENES. 

Tiemann and Semmler 1 also confirmed Bouchardat's view, and 
Barbier and Bouveault 2 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 3 and, more recently, by 
those of Semmler. 4 It has also been found in pelargonium oil 
(African geranium oil) by Gintl, 5 and in the oil of citronella by 
Schimmel & Co. 6 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, 7 the oil from the fresh 
leaves and branchlets of Eucalyptus macarthuri contain sixty 
per cent, of geranyl acetate, 10.64 per cent, of free geraniol, 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 8 ). 

In an investigation of the oil of rose, Eckart 9 discovered an 
alcohol, C 10 H 18 O, to which he gave the name " rhodinol" Mark- 
ownikoff and Reformatzky 10 examined rose oil and came to the 
conclusion that it contained an alcohol, C 10 H 20 O, which they 
called "roseol " Barbier u rejected this conclusion, and confirmed 
Eckart's observations. Tiemann and Semmler 1 further de- 
termined that u rhodinal," C 10 H 16 O, which is obtained by the 
oxidation of Eckart's "rhodinol," C 10 H 18 O, is identical with 
garanial, C 10 H 16 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 12 and the ethereal 

1 Tiemann and Semmler, Ber., 26, 2708. 

^Barbier and Bouveault, Compt. rend., 121, 168. 

sjacobsen, Ann. Chem., 157, 232. 

4 Semmler, Ber., 23, 1098. 

5 Gintl, Jahresb. Chem., 1879, 941. 

6 Semi- Annual Report of Schimmel & Co., Oct., ^8.9.?, and German Patent, 
No. 76,435; Ber., 27, 953, Ref.; compare Journ. pr. Chem. [2], 49, 191, and 
Dodge, Amer. Chem. Journ., 18S9, 456; Ber., 23, 175, Ref. 

7 H. G. Smith, Chem. News, 83, 5. 

^Bertram and Gildemeister, Journ. pr. Chem. [2], 49, 185; Gildemeister 
and Stephan, Arch. Pharm., 234, 321. 

"Eckart, Arch. Pharm., 229, 355. 

lu Markownikoff and Reformatzky, Journ. pr. Chem. [2], 48, 293; Ber., 
27, 625, Ref. 

"Barbier, Compt. rend., 117, 177 and 1092. 

i 2 Dupont and Guerbain, Compt. rend., 123, 700. 



GERANIOL. 389 

oils of the genus Pelargonium contain geraniol, C 10 H 18 O, together 
with considerable quantities of another alcohol, citronellol, C 10 H 20 O. 
The terpene alcohol " reiiniol" prepared by A. Hesse * from 
Reunion geranium oil by means of its camphoric acid ester, has 
been shown to be a mixture 2 of geraniol, C 10 H 18 O, and citronellol, 

C 10 H 20- 

Erdmann and Huth 3 suggested that the name "rhodinol" be 
substituted for that of geraniol ; this suggestion, however, can not 
be accepted. 

Barbier and Bouveault 4 obtained an alcohol from the volatile 
oil of Andropogon sohoenanthus ; they considered it an individual 
chemical compound, and called it " lemonol" Bertram and Gil- 
demeister 5 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, 6 chemists of Schim- 
mel & Co., Leipzig, have practically proved that geraniol, C 10 H 18 O, 
is identical with " lemonol " (Barbier and Bouveault), and with 
" rhodinol " (Erdmann and Huth, and Poleck) ; citronellol, 
C 10 H 20 O (Tiemann and Schmidt) is identical with " rhodinol " 
of Barbier and Bouveault and with " runiol " (Hesse, Naschold) ; 
Eckart's " rhodinol " is a mixture of geraniol and citrouellol, 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. 

>A. Hesse, Journ. pr. Chem., 50 [II.], 474; 53 [II.], 23; Wallach and 
Naschold, Naschold's Inaug. Diss., Gb'ttingen, 1896. 

*Schimmel & Co., Semi- Annual Report, April, 1895, 37 and 63; Tieraann 
and Schmidt, Ber., 29, 903. 

"Erdmann and Huth, Journ. pr. Chem., 53 [II], 42; 56 [II], 1; Poleck, 
Ber., 31, 29; Journ. pr. Chem., 56 [II.], 515; Bertram and Gildemeister, 
Journ. pr. Chem., 56 [II.], 506. 

Barbier and Bouveault, Compt. rend., 118, 1154 and 1208; 119, 281 
and 334; 122, 393; Bull. Soc. China., 15 [III.], 594; Barbier, Compt. rend., 
126, 1423; Tiemann, Ber., 31, 2989; Barbier, Bull. Soc. Chim., 21 [II.], 635. 

s Bertram and Gildemeister, Journ. pr. Chem., 53 [II.], 225; Schimmel 
& Co., Semi- Annual Report, April, 1898, 33. 

eSchimmel & Co., Semi- Annual Report, April, 1896, .37; Oct., 1S96, 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 l that geraniol combines with calcium chloride. Ac- 
cording to Bertram and Gildemeister, 2 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 3 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 r\ D = 1 .4766 
to 1.4786. The specific gravity of geraniol increases rapidly when 
it is allowed to stand in the air (Tiemann and Semmler 4 ). 

Jacobsen, Ann. Chem., 157, 232. 

Semi- Annual Report of Schimmel & Co., 1895, 38. 

sTiemann and Kriiger, Ber., 29, 901; Haller, Compt. rend., 122, 865; 
Erdmann, Journ. pr. Chem., 56 [II.], 17; Flatau and Labbe", Compt. rend., 
126, 1725; Bull. Soc. 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 10 H 17 C1, 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, 1 when geraniol is saturated with hy- 
drogen chloride, the compound, C 10 H 18 C1 2 , is formed ; when this 
substance is boiled with water, it yields a product intermediate be- 
tween C 10 H 18 C1 2 and C 10 H 18 O. 

Isomeric chlorides, C 10 H 17 C1, are probably produced by the 
action of hydrogen chloride on geraniol ; they are converted into 
geraniol and linalool by the action of alcoholic potash. 2 

Geranyl bromide dihydrobromide, 3 C 10 H 17 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 10 H 18 (OH) 2 . 

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. 4 

On heating geraniol with water in an autoclave at 240 to 
250, it is decomposed into hydrocarbons (dipentene). 3 

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. 5 

Formic acid acts on geraniol at 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. 6 

'Reychler, Bull. Soc. Chem., 15 [III.], 364; Barbier and Bouveault, 
Bull. Soc. Chim., 15 [III.], 594. 

sTiemann, Ber., 31, 808. 

3 Naschold, Inaug. Diss., Gottingen, .7896. 

'Bouchardat, Compt. rend., 116, 1253; Stephan, Journ. pr. Chem., 58 
[II.], 111. 

5 Stephan, Journ. pr. Chem., 60 [II.], 244. 

eTiemann 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. 1 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, 2 when " lemonol " (geraniol) is heated with 
a concentrated, alcoholic solution of potash at 150 for eight 
hours, it yields a tertiary alcohol, C 9 H, 8 O, dimethyl heptenol. 
According to Tiemann, 3 however, this reaction gives rise to methyl 
heptenol (methyl hexylene carbinol), C g H I6 O. On similar treat- 
ment, linalool is hardly altered. 

On oxidation of geraniol with chromic acid, geranial, C 10 H 16 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 4 
derive the formula for geraniol : 

CH 3 = CH CH 2 CH 2 C = CH CH 2 OH. 

CH 3 CH 3 

Dimethyl-2, 6-octadiene-2, 6-ol-8. 

Geranyl acetate, C ln H, 7 OCOCH 3 , is found, together with gera- 
niol, in certain ethereal oils, and may be prepared by boiling gera- 

> Bertram and Walbaum (Gildemeister), Journ. pr. Chem., 49 [ILL 185; 
53, 236. 

zBarbier, Compt. rend., 126, 1423. 

sTiemann, Ber., 31, 2991; Schimmel & Co., Semi- Annual Report, Oct., 
1898, 61. 

'Tiemann 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 0.91 74 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. 

G-eranyl diphenylurethane, 1 (C 6 H 5 ) 2 N-CO-OC 10 H J7 , is a compound 
well adapted for the characterization of geraniol ; it crystallizes 
from eighty per cent, alcohol in long, silky needles, melting at 
82.2. It forma a tdrabramide, which melts at 129 to 132. 

Geranyl hydrogen phthalate, C IO H 17 O-CO-C 6 H 4 -COOH, may be 
used for the isolation and preparation of pure geraniol. It was 
obtained by Erdmann 2 as a colorless oil by heating " rhodinol " 
with finely powdered phthalic anhydride on the water-bath. 
According to Flatau and Labbe", 3 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 10 H 17 Br 4 O-CO-C 6 H 4 -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 10 H, 9 OH. 

As has already been mentioned under menthone, menthonitrile, 
on reduction, yields two bases, menthonylamine, C 10 H 19 NH 2 , and 
oxyhydromenthonylamine, C, H 20 (OH)NH 2 . 

i Erdmann, Journ. pr. Chem., 53 [II.], 42; 56 [II.], 28. 
*H. Erdmann and Huth, Journ. pr. Chem., 56 [II.], 17; see Erdniaiin, 
Ber., 31, 356. 

s Flatau and Labbg, Compt. rend., 126, 1725. 



394 THE TEKPENES. 

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 10 H 19 OH, together 
with its nitrous acid ester, and small quantities of a hydrocarbon, 
C 10 H 18 (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, n^ = 1.44809, at 20 ; it is feebly 
dextrorotatory, []# = + 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 10 H 18 O ; it is, therefore, a 
primary alcohol (Wallach 1 ). 

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 10 H 20 - 
(OH) 2 , is formed by the action of nitrous acid on oxyhydromen- 
thonylamine, C 10 H 20 (OH)NH 2 ; it boils at 153 to 156 (19 mm.), 
and is converted into menthocitronellol by the action of dilute 
sulphuric acid (Wallach 2 ). 

4. CITRONELLOL, C 10 H 19 OH. 

It has already been mentioned that mixtures of geraniol and an 
alcohol, C 10 H, O, have been described under the names of " rho- 
dinol," 3 " reuniol," 4 and " roseol." 5 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 10 H 2(J O, the terms "rhodinol" and "re'uniol " were applied to 
the latter compound. Owing to the close relation which this 
alcohol bears to citronellal, being prepared from the latter com- 

' Wallach, Ann. Chem., 278, 315; 296, 129. 
* Wallach, Ann. Chem., 296, 120. 

3 Eckart, Archiv. d. Pharm., 229, 355; Barbier and Bouveault, Compt. 
rend., 119, 281 and 334; 122, 529. 

*A. Hesse, Journ. pr. Chem., 50 [II.], 472. 
5 Markownikow, Journ. pr. Chem., ^8 [II.], 293. 



CITRONELLOL. 395 

pound by reduction, Tiemann and Schmidt l 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 2 obtained pure 1-citronellol by heating a mixture of 
this alcohol 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 geranyl 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 Labbe" 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. 3 When obtained by this method, it boils at 117 to 
118 under 17 mm. pressure, has the specific rotatory power, 
\a\ D = + 4, the sp. gr. 0.8565 and the refactive index, n^ = 
1.45659 (Tiemann and Semmler). 

According to Wallach, citronellol ("runiol") boils at 114 to 
115 (12 to 13 mm.), has the sp. gr. 0.856 at 22, n 1) = 1.45609 
at 22, and [] Z) = - 1 40 X . 

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, 

'Tiemann and Schmidt, Ber., 29, 921. 
2 leasehold, Inaug. Diss., Gottingen, 1896. 

a Dodge, Amer. Chem. Journ., 11, 463; Tiemann and Schmidt, Ber., 
29, 906. 



396 THE TERPENES. 

boils at 144 to 146 (10 ram.), 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 10 H 18 O, to citronellol, C 10 H 20 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, etc. 

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 /2-methyl 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 /3-methyl adipic acid crys- 
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 3V 

>C=CH CH 2 CH 2 CH C J i 2 CH 2 OH. 

CH/ AH. 

The fatty acid esters of citronellol may be readily formed by 
treating the alcohol with the corresponding acid anhydrides. 

Citronellol acetate, C 10 H 19 OCOCH 3 , is a colorless liquid, Having 
a pleasant odor somewhat similar to that of bergamot oil ; it boils 
atll9tol21 (15 mm.), has the rotatory power, [a] ^ = + 2 37', 
the sp. gr. 0.8928, and refractive index, n^ = 1.4456, at 17.5. 

CitroneUol formate boils at 97 to 100 (10 mm.). 

Citronellol hydrogen phthalate, 1 C 10 H 19 O-CO-C 6 H 4 COOH, is 
formed by heating the free alcohol 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 10 H 16 O. 

In the year 1888, the chemists of Schimmel & Co., Leipzig, 
determined that lemon oil contains about six to eight per cent, of 

'H. Erdmann, Journ. pr. Chem., 56 [II.], 1; Flatau and Labb6, Compt. 
rend., 126, 1725. 



GERANIAL,. 397 

an aldehyde, C 10 H 16 O, and that the characteristic odor of oil of 
lemon is due to this aldehyde, which was termed citral. 1 

Semmler 2 had also obtained an aldehyde, C 10 H 16 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 this compound. 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. 

Geranial has been found in bay oil (Power and Kleber 3 ), in 
citronella fruit oil, in cedro oil, in eucalyptus oils of JSackhousia 
dtriodora and Eucalyptus staigeriana, in lemongrass oil, Japanese 
pepper oil of Xanihoxylum 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 4 ). 

Fifteen grams of geraniol are added, all at once, to a solution 
often 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. 

PROPERTIES. 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 5 ). 
It has the characteristic properties of an aldehyde, reducing a sil- 
ver solution, and coloring a fuchsine-sulphurous acid solution. 

l For the history of citral, compare Tiemann, Ber., 31, 3278. 

zSemmler, Ber., 23, 2965; 24, 201. 

3 Power and Kleber, Pharm. Rundsch., 1895, No. 13. 

'See also Tiemann, Ber., 81, 3311. 

5 Tiemann 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 l by the distillation of a mixture 
of the calcium salts of formic and geranic acids. 

Geranial forms a liquid, additive compound with four atoms of 
bromine. It is very sensitive towards acids. According to 
Semmler, 2 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 3 also decompose geranial ; when treated with caustic soda, 
it suffers a partial decomposition into methyl heptenone, C 8 H 14 O, 
acetaldehyde, and resinous substances. Geranial is converted into 
the corresponding primary alcohol, geraniol, on reduction. 4 

The behavior of geranial towards sodium bisulphite has been 
studied by Tiemann and Semmler. 5 The normal additive com- 
pound of geranial and sodium bisulphite, C 9 H 15 -CH(OH)-SO 3 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 9 H 17 (SO 3 Na) 2 ' 
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 labile disulphonic 
derivative in solution, and then to decompose it with alkali. 
Sodium geranial hydrosulphonate results on shaking the labile di- 

i Tiemann, Ber., 31, 827. 

Semmler, Ber., 23, 2965; 2%, 201; Tiemann, Ber., 32, 107. 

aVerley, Bull. Soc. Chim., 17 [III.], 175; Tiemann, Ber., 32, 107. 

* Tiemann, Ber., 31, 828. 

sTiemann 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 1 in the case of acrolein, and 
by Heusler 2 and by Tiemann 3 regarding cinnamic aldehyde. 

Geranial- (citral-) /9-naphthocincnonic acid, C^H^NC^. This de- 
rivative of geranial, first prepared by Doebner, 4 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 /3-naph- 
thylamine, yielding alkyl-/9-naphthocinchonic acids ; the geranial 
derivative is obtained according to the equation : 

C 9 H 15 CHO + CH 3 COCOOH + C r 

A 



V 1 

COOH. 

It is prepared by boiling an alcoholic solution of twenty 
grams of geranial, twelve grams of pyroracemic acid and twenty 
grams of /9-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 . 5 The hydrochloride of geranial- 
/9-naphthocinchonic acid crystallizes from alcohol in orange-yellow 
needles. 

Geranyl phenylhydrazone, C 10 H 16 N 2 HC 6 H 5 , is an oil, which de- 
composes when distilled in a vacuum (Tiemann and Semmler). 

The anilide, C 10 H 16 = NC 6 H 5 , is formed by heating geranial 
and aniline at 150; it is a yellow liquid, boiling at 200 under 
a pressure of 20 mm. 

' Miiller, Ber., 6, 1441. 

* Heusler, Ber., 2-' t , 1805. 

sTiemann, Ber., 31, 3297. 

'Doebner, Ber., 27, 352 and 2020; 31, 1888 and 3195; compare also 
Ber., 31, 3331; 32, 115. 

sThe melting point is frequently reported at 200 or slightly above thig 
point. 



400 THE TEKPENES. 

Dry ammonia also reacts with geranial, yielding an oil which 
can not be distilled without decomposition in a vacuum. 

Geranialoxime, C 10 H lg 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, n^ = 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 10 H 16 = N NHCONH 2 . A number 
of isomeric semicarbazones appear to have been obtained from 
geranial by different investigators. Wallach l mentions two such 
derivatives, melting at 150 and 160; Tiemann and Semmler 2 
describe a semicarbazone, melting at 130 to 135. Barbier and 
Bouveault 3 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 alco- 
hol. The fraction of the same oil, boiling at 110 to 112 (10mm.), 
gives three isomeric derivatives, melting at 171, 160 and 135, 
respectively. 

According to more recent investigations by Tiemann, 4 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, 5 ordinary geranial 
consists of two geometrical isomerides termed geranial a and gera- 
nial b. 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 

1 Wallach, Ber., 28, 1957. 

2 Tiemann and Semmler, Ber., 28, 2133. 

3 Barbier and Bouveault, Compt. rend., 121, 1159. 
* Tiemann, Ber., 32, 115; 31, 3324. 
sTieraann, Ber., 32, 115; 33, 877. 



GERANIC ACID. 401 

refractive index, n^, = 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 cyanoacetic add, 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 n^ = 1.49001, 
at 19. Its oxime boils at 136 to 138 (11 mm.), its semicarba- 
zone melts at 171, and its fi-naphthocinchonic acid melts at 
200. 

G-eranionitrile, C 9 H 15 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 1 10 
under 10 mm. pressure, has the specific gravity 0.8709 and the 
refractive index, n^ = 1.4759, at 20 (Tiemann and Semmler). 

Geranic acid, C 9 H 15 COOH, is prepared by warming geranial 
with moist silver oxide (Semmler 1 ). It may be more conveniently 
obtained by boiling geranionitrile with alcoholic potash until am- 
monia is no longer eliminated (Tiemann and Semmler 2 ). 

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, n^ = 1.4797, at 20. 

A partial synthesis 3 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 10 H 17 O 2 OC 2 H 5 . When this compound is boiled with acetic 
acid and some zinc chloride, the ethyl ester of geranic acid is 
formed ; or, if the acid, C 10 H 17 O 2 OH, corresponding to the com- 
pound, C 10 H 17 O 2 OC 2 H 5 , is boiled with acetic anhydride, it is con- 
verted into geranic acid. 

Geranic acid is converted into citronellic acid, C 10 H 18 O 2 , when 
it is reduced with sodium and amyl alcohol. 

Semmler, Ber., 23, 2965; 24, 201. 
2 Tiemann and Semmler, Ber., 26, 2708; 28, 2137. 

sBarbier and Bouveault, Compt. rend., 122, 393; compare Tiemann, Ber., 
S3, 559. 

26 



402 THE TEEPENES. 

Geraniolene, C 9 H 16 . 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, n^ = 1.4368, at 20. 
It forms a liquid tetrabromide, C 9 H 16 Br 4 . 

Geranic acid, geraniolene, and other compounds of the geranial 
series may be very readily converted into a mixture of two isomeric 
cyclic 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 /?, /3-dimethyl 
adipic acid, while those of the /9-series may be referred back to 
geronic acid and a, a-dimethyl adipic acid. 1 

a- and /?-Cyclo -geranic acids, 1 C 9 H 15 COOH. When geranic 
acid is shaken with sixty-five to seventy per cent, sulphuric acid 
at 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 /9-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 /9-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 di bromide which 
melts at 121. Oxidation with potassium permanganate con- 
verts the a-acid into dioxydihydrocyclogeranic acid, C 9 H 15 (OH) 2 .- 
COOH, melting at 198 to 200, and keto-oxydihydrocydogeranic 

ir Tieniann 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- AND /3-CYCLO-GEEANIONITEILES. 403 

acid, C 10 H 16 O 4 , 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 8 H 15 O COOH, is formed j 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-{3, ft,-dimethyl adipic acid, 

/COOK 
C 8 H U 0/ 

X COOC 2 H 5 ; 

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 /?, f-unsaturated acid, and that it may be termed methyl-1- 
dimethyl-5-cyclohexene-l-methyl-acid-6. 

/3-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 {3-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 /?-cyclo-geranic acid into an oxy-acid, C 10 H 16 O 3 , 
which melts with decomposition at 186, a ketonic acid, C 9 H ]2 O 3 , 
which melts at 189 and yields a semicarbazone melting at 240, 
and, as chief product, a, ct-dimethyl glutaric acid. 

a- and /9-Oyclo-geranionitriles, 1 C 9 H 15 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 /9-cyclo-acids and 
their derivatives. The mixture of the two nitriles boils at 87 to 

iTiemann and Semmler, Ber., 26, 2725; Tiemann and Schmidt, Ber., 
31, 881; Tiemann, Ber., 33, 3705; compare Barbier and Bouveault, Bull. 
Soc. Chim., 15 [III.], 1002. 



404 THE TERPENES. 

88 (11 mm.), has the sp. gr. 0.9208 and the refractive index, 
Dp = 1.4734, at 20. It forms an amidoxime, melting at 165, 
whilst the corresponding compound of the aliphatic geranionitrile 
is a liquid. 

a- and /3-Cyclo-geraniolenes, C 9 H, 6 , 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, n^ = 1.4434, at 22. 

Oxidation with permanganate converts this mixture of a- and 
/9-cyclo-geraniolenes into isogeronic acid, C 8 H 16 O.COOH, which 
gives a semicarbazone melting at 198 and insoluble in ethyl ace- 
tate, and geronic acid, C 8 H 15 O.COOH, which yields a semicar- 
bazone melting at 164 and readily soluble in ethyl acetate ; geronic 
acid 1 is an open-chain compound and is also a product of the oxi- 
dation of ionone with permanganate. 

a- and /?-Cyclo-geranials, 2 C 10 H, 6 O. 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 into cymene. 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 /3-cyclo-derivatives) ; when 
the latter is hydrolyzed with potash, a mixture of a- and /3-cyclo- 
geranial is formed, of which only the /9-compound has so far been 
obtained in a pure condition. 

/?-Cyclo-geranial is a colorless oil, having the odor of carvone ; 
it boils at 88 to 91 (10 mm.) or 95 to 100 (15mm.), has the 
sp. gr. 0.959 at 15 and 0.957 at 20, and the refractive index, 
U D = 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 /9-cyclo-geranial. 

/3-Cyclo-geranial forms an additive compound, C U H 21 O 2 N 3 , with 
semicarbazide, which crystallizes from a mixture of ethyl acetate 
and benzene in needles, and melts with decomposition at 250. 

iTiemann, Ber., SI, 808. 

Tiemann, Ber., 33, 3719; Schmidt, Ber., 34, 2451. 



GERANIALIDENE BIS ACETYL ACETONE. 405 

When /?-cyclo-geranial is condensed with acetone, ft-ionone is 
formed. 

/?-Cyclo-geranial is readily oxidized into /3-cyclo-geranic acid on 
exposure to the air. On oxidation with potassium permanganate, 
/3-cyclo-geranial yields /3-cyclo-geranic acid and oxidation products 
of this acid, together with geronic acid, C 9 H 16 O 3 , the methyl 
ketonic acid corresponding to a, a-dimethyl adipic acid. 

Geranialidene cyanoacetic acid, 1 C 9 H 15 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. 

Q-eranialidene bisacetylacetone 2 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. 

Labb6 3 mentions a polymeride of geranial, (C 10 H 16 O) x , which 
results by the action of alcoholic potash on geranial. It melts at 
81 to 82. 

It should be mentioned that, according to Stiehl, 4 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 8 H 14 O, is formed (Tiemann and Semmler 5 ). This ketone is 
identical with the compound previously prepared by Wallach by 
the distillation of cineolic anhydride. The identity of these two 

'Tiemann, Ber., SI, 3324; 33, 877 and 3720; Verley, Bull. Soc. China., 
21 [III.], 413 and 414. 

K. Wedemeyer, Inaug. Diss., Heidelberg, 1897. 
Labb6, Bull. Soc. Chim., 21, 407. 
*W. Stiehl, Journ. pr. (_'l:ein., Jtf, 51. 
s Tiemann and Semmler, Ber., 26, 2708. 



406 THE TERPENES. 

ketones, C g H 14 O, has been determined by Tiemann and Semmler 
by the formation of tribromo-methyl hexylene carbinol (tribromo- 
heptanonol), C 8 H 12 Br 3 OOH ; 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 8 H 14 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 8 H 15 OH, results, together 
with geranic acid and methyl hexylene ketone, in the hydrolysis 
of geranionitrile. 

It should be especially noted that methyl heptenone, C 8 H 14 O, 
occurs, together with geraniol and geranial, in many ethereal 
oils. Its constitution has been explained by Tiemann and 
Semmler's 1 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 9 H 15 (OH) 2 COOH, is obtained 
which gives methyl hexylene ketone on distillation (Tiemann 
and Semmler). According to Barbier and Bouveault, 2 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 9 H 15 (OH) 2 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 3 first prepared geranialoxime, and con- 
verted it into geranionitrile and then into geranic acid. Geranic 
acid was previously described by Eckart 4 under the name " rho- 
dinolic acid." 

From the results of their experiments, Tiemann and Semmler l 

1 Tiemann and Semmler, Ber., 28, 2126. 

'Barbier and Bouveault, Compt. rend., 118, 1050; 122, 393. 

3 Barbier, Compt. rend., 116, 883. 

*Eckart, Arch. Pharm., 229, 355. 



CC-IONONE. 407 

regard the following formulas as expressing the true constitution 
of geranial and its derivatives : 

CH S C=CH CH a CH, C=CH CHO, 

CH 8 CH S 

Geranial (citral) (dimethyl-2, 6-octadiene-2, 6-al-8). 

CH, C=CH CHj CH 2 C=CH COOH 

CH 3 CH S 

Geranic acid (dimethyl-2, 6-octadiene-2, 6-acid-8). 

CH S C=CH CH 2 CH a CO CH 3 

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, 1 C 13 H 20 O ; 
its constitution is represented by the formula, 

CH 3 C=CH CH 2 CH, C==CH CH=CH CO CH,. 
CH S CHj 

Pseudoionone, C 13 H 20 O, boils at 143 to 145 under a pressure of 
12 mm., has the specific gravity 0.9044, and the refractive power, 
np = 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 {3-ionone. This mixture was at first thought to be 
an individual chemical compound and was called ionone, 1 C 13 H 20 O. 
It boils at 126 to 128 (12 mm.), has the sp. gr. 0.9351 and the 
refractive index, n^ = 1.507, at 20. 

a-Ionone, 2 C 13 H 20 O, is prepared from a mixture of the a- and 
/3-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, n^, = 1.4980. Its oxime crystallizes from petro- 
leum and melts at 89 to 90, while the oxime of /3-iouone is a 
liquid, hence a separation of the two ketones is rendered possible. 
The semicarbazone dissolves more readily than the /9-derivative in 
petroleum, and melts at 107 to 108. Other characteristic de- 
rivatives have been prepared. 

iTiemann and Kriiger, Ber., 26, 3691. 

"Tiemann, Ber., 31, 808 and 867; 83, 3704 and 3726; compare Lemme, 
Chem. Centrl., 1900 [I.], 576. 



408 THE TERPENES. 

/9-Ionone, C 13 H 20 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, iij, = 1.521. Its oxime is an oil, and its 
semicarbazone melts at 148 to 149. 

Oxidation with permanganate converts a-ionone into isogeronic 
acid, C 9 H 16 O 3 , and oxidation products of the latter, while /?-ionone 
gives rise to geronic acid and its oxidation products. The con- 
stitutional formulas of the two ketones are : 



CH CH. CH, 

3 



H.C C< H.C C CH = CH CO CH, 

\CH = CH-CO-CH 3 

H,C /X C-CH 8 H,C C-CH, 

CH, 
H 

a-Ionone. /?-Ionone. 

Commercial ionone has the characteristic odor of violets, and 
for this reason it is of considerable practical importance. 1 

Irone, 1 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, n^ = 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., 21 [III.], 419 and 423. 

Barbier, Bull. Soc. Chim., 21 [III.], 635. 

Corie, C. and D., 54, 650. 

Doebner, Ber., 81, 3195. 

Flatau, Bull. Soc. Chim., 21 [III.], 158. 

Flatau and Labbg, Bull. Soc. Chim., 19 [III.], 1012. 

Ipatieff, Ber., 34, 594. 

Labbg, Bull. Soc. Chim., 21 [III.], 77, 407 and 1026. 

Semmler, Ber., 81, 3001. 

Stiehl, Journ. pr. Chem., 58, 51. 



and Kriiger, Ber., 26, 2675; 28, 1754; Barbier and Bouveault, 
Bull. Soc. Chim., 15 [III.], 1002; Tiemann, Ber., SI, 808, 867, 1736, 2313, 
and 3324; 32, 115; 33, 877, 3704 and 3726; Ziegler, Journ. pr. Chem., 57 
[II.], 493. 



CITRONELLAL. 409 

Tiemann, Ber., 31, 2313, 3278, 3297 and 3324 ; 38, 107, 250, 
812, 827 and 830. 

Verley, Bull. Soc. Chim., 21 [III.], 408, 413 and 414. 
Ziegler, Journ. pr. Chem., 57 [II.] , 493. 

2. MENTHOCITRONELLAL, C 10 H 18 O. 

This aldehyde, 1 previously termed menthonyl 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, n^, = 
1.43903, at 20. 

Menthocitronellal-/9-naphthocinchonic acid is formed by the con- 
densation of the aldehyde with /9-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. CITRONELLAL, C 10 H 18 O. 

This compound was formerly called " citronettone " ; 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, 2 Wright, 3 
Kremers, 4 and Dodge. 5 It has been found by Schimmel & Co. in 
the oils of Eucalyptus maculata and Eucalyptus maculata var. 
citriodora, and, according to Dobner, 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. 

iWallach, Ann. Chem., 278, 313; 296, 120. 

^Gladstone, Journ. Chem. Soc., 1872, 7. 

aWright, Journ. Chem. Soc., 1875, 1. 

'Kremera, Proc. Amer. Pharm. Assoc., 1887; Amer. Chem. Journ., 14, 
203 ; Ber., 25, 644, Ref. 

5 Dodge, Amer. Chem. Journ., 11, 456; IS, 553; Ber., 23, 175, Ref.; 24, 
90, Ref. 



410 THE TEBPENES. 

Citronellal may also be prepared by the oxidation of citronellol 
with chromic acid ; the yield, however, is small. 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 
[a]^ = -f- 8.18, and by Tiemann and Schmidt, 1 [0]^= + 
1230'. 

Pure citronellal is very unstable ; when allowed to stand for 
several months, it is almost entirely converted into isopulegol ; 2 
the same isomeric change is effected much more rapidly by the 
action of acids. 8 When citronellal is treated with alkalis, it is 
completely resinified. 

When it is reduced in alcoholic solution with glacial acetic acid 
and sodium amalgam, it yields citronellol, C 10 H 19 OH (Dodge, 
Tiemann and Schmidt). 

On oxidizing citronellal with silver oxide, citronellic acid, 
C 10 H 18 O 2 , is obtained (Semmler). Oxidation with potassium per- 
manganate, followed by chromic and sulphuric acids, converts 
citronellal, like citronellol and citronellic acid, into acetone and 
/9-methyl adipic acid. The aldehyde is, therefore, to be regarded 
as dimethyl-2, 6-octene-2-al-8 (Tiemann and Schmidt): 

CH, C=CH CH, CH 2 CH CH, CHO. 
CH S CH 3 

It unites with two atoms of bromine, forming a liquid additive 
product (Dodge, Semmler). 

According to Barbier, 4 menthoglycol, C 10 H 18 (OH) 2 , is formed by 
agitating citronellal with dilute sulphuric acid. 

The normal addition-product of citronellal and sodium bisul- 
phite, 5 C 10 H 18 O'NaHSO 3 , 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 add are also described. 5 

1 Tiemann and Schmidt, Ber., 29, 905. 

*Labbe, Bull. Soc. Chim., 21 [III.], 1023; compare Tiemann, Ber., 
32, 825. 

"Tiemann and Schmidt, Ber., 29, 913; 80, 22. 
*Barbier and Leser, Compt. rend., 124, 1308. 
sTiemann, Ber., 31, 3297. 



CITRONELLAL-/3-NAPHTHOCINCHONIC ACID. 411 

Citronellylidene cyanoacetic acid, 1 C U H 18 (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, 2 C 10 H 18 (OCH 3 ) 2 , 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. It is a 
monobasic acid, forms crystalline salts, and has the formula 
(Dodge) : 



Ll f VJ. -L V7 -7 J 

H <X 

C it ronellal ^ 5 -naphtho cinchonic acid , 



C=CH 
COOH 

was discovered by Dobner. 

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 /9-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-/9-naphthyl quinoline ; this 
amine crystallizes from dilute alcohol or petroleum ether in bright 
needles, which melt at 53. 

iTiemann, Ber., 32, 824. 

"Harries, Ber., 33, 857; 34, 1498 and 2981. 



412 THE TERPENES. 

Citronellaloxime, 1 C 10 H 18 NOH, was obtained by Kremers, and 
subsequently by Semmler, 1 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, n^ = 1.4763, at 20. 

Citronellonitrile, 1 C 9 H 17 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, n^ = 1.4545, 
at 20; the molecular refraction is 47.43. 

Oitronellic acid, C 9 H 17 COOH, was prepared by Dodge, 2 Semm- 
ler, 3 and Kremers 4 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 5 ). It 
boils at 143.5 (10 mm.) and at 257 under atmospheric pres- 
sure ; its specific gravity is 0.9308 and the refractive power, 
n^ = 1.4545, at 20. The molecule of citronellic acid appears to 
contain one double linkage. 

Citronellic acid is further obtained from geranic acid, 
C 9 H 15 COOH, by reduction with sodium and amyl alcohol. 6 

A small amount of citronellal is formed by strongly heating a 
mixture of calcium citronellate and formate. 6 

Citronellamide, 6 C 9 H 17 CONH 2 , 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 9 H 17 (OH) 2 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 7 H 12 O 4 (Semmler' s citronellapimelic'acid). 

Citronellal semicarbazone, 7 C 10 H 18 = N NHCONH 2 , 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. 

1 Semmler, Ber., 26, 2254; compare Tiemann and Kriiger, Ber., 29, 926; 
Tiemann and Schmidt, Ber., 30, 33. 

"Dodge, Amer. Chem. Journ., 11, 456; 12, 553. 

3 Semmler, Ber., 24, 208. 

* Kremers, Amer. Chem. Journ., H, 203. 

5 Semmler, Ber., 26, 2254 ; compare Tiemann and Schmidt, Ber., SO, 33; 
Barbier and Bouveault, Compt. rend., 122, 673, 737, 795 and 842. 

eTiemann, Ber., 31, 2899. 

'Tiemann and Schmidt, Ber., 30, 34; 31, 3307; compare Barbier and 
Bouveault, Compt. rend., 122, 737. 



OXYHYDKOMENTHONYLAMINE. 413 

C. AMINES. 

1. MENTHONYLAMINE, C 10 H 19 NH 2 . 

According to Wallach, 1 menthonylamine, C 10 H 19 NH 2 , is formed, 
together with oxyhydromenthonylamine, C 10 H 20 (OH)NH 2 , 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, n^ = 1.4500. It is feebly 
dextrorotatory. 

Menthonylamine hydrochloride, C 10 H 19 NH 2 'HC1, is a crystalline 
salt, stable in the air, and forms a sparingly soluble platinochloride. 

The add 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, 

CONHC 10 H 19 

CONHC 10 H 19 

is very soluble in alcohol, and melts at 82 to 83. 

Menthocitronellol (menthonyl alcohol) and a hydrocarbon, 
C 10 H 18 , are produced on treating menthonylamine oxalate with 
sodium nitrite. 

Oxyhydromenthonylamine, C 10 H 20 (OH)NH 2 , 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 10 H 20 (OH) 2 '; it is non-volatile with steam, and 
boils at 153 to 156 under 19 mm. pressure. 

i Wallach, Ann. Chem., 278, 313; 296, 120. 



SESQUITERPENES AND POLYTERPENES. 

SESQUITERPENES, C 15 H 24 , AND SESQUITERPENE 
ALCOHOLS, C 15 H 25 OH. 

1. CADINENE, C 15 H 24 . 

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 l 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, 2 
Schmidt, 3 Oglialoro, 4 Soubeiran and Capitaine 6 have shown that 
cadinene occurs in the oil of cubeb. Wallach 2 also proved that it 
occurs in patchouly oil, galbanum oil and oil of savin ; Wallach 
and Rheindorf 6 subsequently discovered it in the oil of paracoto 
bark, and Wallach and Walker 7 detected it as a constituent of oil 
of olibanum. Bertram and Gildemeister 8 found cadinene in the 
oil of betel leaves and in camphor oil ; Bertram and Walbaum 9 
recognized it in pine needle oil from Pioea exoelsa and Pinus 
montana, and in the German oil of Pinus silvestris. Schimmel & 

'Wallach, Ann. Chem., 271, 297; compare Troeger and Feldmann, Arch. 
Pharm., 236, 692. 

* Wallach, Ann. Chem., 238, 78. 

'Schmidt, Arch. Pharm. [2], 141, 1. 

Oglialoro, Gazz. Chim., 5, 467. 

*Soubeiran and Capitaine, Journ. Pharm., 26, 75; Pharm. Centr., 1840, 
177. 

Wallach and Rheindorf, Ann. Chem., 271, 303. 

Wallach and Walker, Ann. Chem., 271, 295. 

8 Bertram and Gildemeister, Journ. pr. Chem., N.F., 39, 349. 

9 Bertram 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, 1 in oil of asafetida, and, according to Rey- 
chler, 2 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 
Oleum 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 3 ). 

PROPERTIES. 4 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, [8]^= 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 

'Semmler, Arch. Pharm., 229, 17. 

Reychler, Bull. Soc. Chim. [3], 11, 576; Ber., 28, 151, Ref. 
aWallach, 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 15 H 24 2HC1, was first obtained by 
Soubeiran and Capitaine, subsequently by Schmidt, and Oglialoro, 
from the oil of cubeb. According to Wallach, 1 it is most con- 
veniently prepared from Oleum 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 2 ). 

Cadinene dihydrochloride melts at 117 to 118, and has the 
specific rotatory power, \OL\ D = 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, n^ = 1.47439 (Wallach and Walker 3 ). 

Cadinene dihydrobromide, C 15 H 24 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] D = -36.13 (Wallach). 

Cadinene dihydriodide, C 15 H 24 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, 4 C^H^ NOC1, is obtained when a so- 

1 Wallach, Ann. Chem., 238, 82; compare Cathelineau and Hauser, Bull. 
Soc. Chim., 25 [III.], 247 and 931. 
zHintze, Ann. Chem., 238, 82. 
aWallach and Walker, Ann. Chem., 271, 295. 
4 Schreiner 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, 1 C 15 H 24 -N 2 O 4 , 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 15 H 24 . 

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 2 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, n D = 1.50094. It is 
optically active (Wallach). 

According to Schreiner and Kremers, 3 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, 
n^ = 1.49976, at 20, and the specific rotatory power, []/> = 
8.959 at 20. The physical constants have also been deter- 
mined by Erdmann, 4 and by Kremers. 5 

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 ]5 H 24 -2HC1. According to Kre- 
mers, 3 it appears that this compound may be obtained in a crys- 

1 Schreiner and Kremers, Pharm. Arch., 2, 273. 

2 Wallach and Walker, Ann. Chem., 27 1, 285. 
'Schreiner and Kremers, Pharm. Arch., 2, 282. 
Erdmann, Journ. pr. Chem., 56 [II.], 146. 

5 Kremers, Pharm. Arch., 1, 211. 
27 



418 THE TEEPENES. 

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] D = 35.39 ; it is perhaps identical with clov&ne. 

Caryophyllene bisnitrosochloride, (C 15 H 24 ) 2 -N 2 O 2 C1 2 , 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 ft-ben- 
zylnitrolamine ; the ^-compound melts at 167 and is sparingly 
soluble in alcohol, while the /2-modification melts at 128 and is 
readily soluble (Schreiner and Kremers 1 ). 

Caryophyllene nitrosite, 1 C 15 H 24 -N 2 O 3 , 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, [#]# = + 103, in a 1.6 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 fi-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 ]5 H 24 ) 2 '(N 2 O 3 ) 2 , results 
on heating the alcoholic solution of the nitrosite ; it forms color- 
less crystals, and melts at 53 to 56. 

Caryophyllene nitrosate, C 15 H 24 N 2 O 4 , is readily prepared by 

1 Schreiner and Kremers, Pharm. Arch., 1, 209 ; 2, 273. 



CAEYOPHYLLENE 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 16 H 24 N 2 O 4 ) 2 . 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 
14 \NH ' CH 2 C 6 H 5 . 

The a- and /^-modifications are obtained from the bisnitrosochlo- 
ride and benzylamine ; the a- melts at 167, and the /9-nitrolamine 
at 128. The nitrolamine prepared from the nitrosate and benzyl- 
amine is identical with the /9-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. 

Caryophyllene nitrolpiperidide, 1 

!4 \NC S H 10 

results by treatment of the nitrosate with piperidine ; it separates 
from alcohol in transparent crystals, melting at 141 to 143. 

Caryophyllene alcohol, C 15 H 25 OH, is obtained according to the 
method of preparation of terpene alcohols proposed by Bertram, 8 
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 

1 Wallach and Tuttle, Ann. Chem., 279, 391; compare Kremers, Schreiner 
and James, Pharm. Arch., 1, 209. 

2 Bertram, German Patent, No. 80,711. 



420 THE TEEPENES. 

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 to 
289, sublimes in lustrous needles, and may be recrystallized 
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 phenylur ethane, C 15 H 25 O CO NHC 6 H 5 , is pro- 
duced by the action of carbanile on the alcohol. It crystallizes 
from a mixture of alcohol and ether in needles, and melts at 
136 to 137 (VVallach and Tuttle 1 ). 

Caryophyllene acetate, C 15 H 25 OCOCH 3 , may be prepared by 
heating the iodide, C 15 H 25 I, with sodium acetate and glacial acetic 
acid. The product partially solidifies and is recrystallized from 
methyl alcohol (Wallach and Tuttle J ). 

Caryophyllene chloride, 2 C 15 H 25 C1, 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, 2 C 15 H 25 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 15 H 25 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. 

1 Wallach and Tuttle, Ann. Chem., 279, 391. 
"Wallach and Walker, Ann. Chem., 271, 285. 



HUMULENE. 421 

A hydrocarbon, C 30 H 50 , 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 15 H 25 ONO 2 , is produced by dissolving 
caryophyllene 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. 

It 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 15 H 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, n^ = 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 15 H M . 

The ethereal oil of hops contains a terpene, C 10 H 16 , which pos- 
sibly belongs to the series of olefinic terpenes, a hydrocarbon, 
C 10 H 18 , an oxidized compound which resembles geraniol, and, as 

i Wallach and Walker, Ann. Chem., 271, 294 and 298. 



422 THE TEKPENES. 

the chief constituent, a sesquiterpene which boils at 166 to 171 
under a pressure of 60 mm.; this sesquiterpene is called humulene 
(Chapman 1 ). 

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 15 H 24 NOC1, is a white, crystalline 
substance, which melts and decomposes at 164 to 165. 

Humulene nitrosate, C 15 H M -N a O 4 , melts at 162 to 163. 

Humulene nitrolpiperidide, 

/NO 

NC 6 H 10 

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 

NH-CH S C,H 5 

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 15 H 24 N 2 O 3 . Nitrous acid reacts with 
humulene forming two compounds, one of which is probably a 
true nitroso-, the other an isonitroso- or bisnitroso-derivaiive. 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, 2 the principal fraction 

1 Chapman, Journ. Chem. Soc., 1895 (1), 54 and 780; Ber., 28, 303 and 
920, Ref. ; compare Kremers, Pharm. Arch., 1, 209. 

* Fichter and Katz, Ber., 82, 3183. 



CEDRENE AND CEDROL. 423 

obtained from this oil boils at 132 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]^ = 1048' at 22 ; its 
vapor density corresponds with that of a compound, C 15 H 24 . It 
yields a nitrosochloride, C 15 H 24 'NOC1, 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"), 

C 15 H 25 OH. 

The ethereal oil of cedar wood consists almost entirely of a 
liquid sesquiterpene, C 15 H 24 , and a solid compound, C 15 H 25 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 1 ). 

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, \_a~\j, = - 47 54' (Rousset 2 ). 

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 12 H, 8 O 3 , 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 ]5 H 25 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 3 ). 
It crystallizes from dilute methyl alcohol in colorless needles, and, 
after repeated crystallizations, it softens at about 78, and melts 
at 85 to 86. 4 It is optically active. 

i Wallach, Ann. Chem., 271, 299. 
"Rousset, Bull. Soc. Chim., lit [III.], 486. 
s Walter, Ann. Chem., 39, 247; 48, 35. 

*Schimmel & Co., Semi- Annual Report, Oct., 1897, 14; compare Rousaet, 
Bull. Soc. Chim., 17 [III.], 485; Chapman and Burgess, Chem. News, 74, 95. 



424 THE TERPENE6. 

Walter observed that, when " cedar camphor " is heated with 
phosphoric anhydride, it is decomposed into water and a sesqui- 
terpene, C 15 H 24 , 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 15 H 25 O - 
COCH 3 , 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 15 H 24 , thus obtained boils at 
262 to 263, and is levorotatory, [a\ D = 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 15 H 24 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 crys- 
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 15 H 25 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 CAMPHOE, C 16 H 25 OH. 

The oil of cubeb, prepared from old cubebs, contains the sesquiter- 
pene cadinene, and a sesquiterpene alcohol, C 15 H 25 OH ; this alcohol 
has been the subject of investigations by Blanchet and Sell, 1 Wink- 
ler, 2 Schaer and Wyss, 3 and Schmidt. 4 Cubeb camphor separates 
from a mixture of ether and alcohol in large, odorless, rhombic crys- 
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. 

i Blanchet and Sell, Ann. Chem., 6, 294. 

"Winkler, Ann. Chem., 8, 203. 

3 Schaer and Wyss, Jahresb. Chem., 1875, 497. 

'Schmidt, Zeitschr. fur Chem., 1870, 190; Ber., 10, 189. 



PATCHOULY ALCOHOL AND PATCHOULENE. 425 

7. LEDUM CAMPHOR, C 15 H 25 OH, AND LEDENE, C 15 H 24 . 

Ledum camphor l occurs in the oil of Labrador tea, obtained 
from the leaves of Ledum 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, [].= + 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 15 H 24 , which 
is an oil boiling at 255. 

The chloride, C 15 H 25 C1, 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 2 ). 

8. PATCHOULY ALCOHOL, C^H^OH, AND PATCHOULENE, 

C.H,. 

The oil of patchouly contains liquid substances, together with a 
solid compound which was investigated by Gal, 3 and Montgolfier, 4 
and named "patchouly camphor." More recently, Wallach and 
Tuttle 5 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. 

It has long been known that patchouly alcohol can be decom- 
posed by the action of acetic anhydride into water and a sesqui- 
terpene, C 15 H 24 . According to Wallach and Tuttle, the same 
hydrocarbon, patchoulene, 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 apparently contains one 
ethylene linkage. 



, 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. 

2 Hjelt, Ber., 28, 3087. 

Gal, Zeitschr. fur Chem., 1869, 220. 

<Montgolfier, Bull. Soc. Chim., 28, 414. 

5 Wallach and Tuttle, Ann. Chem., 279, 394. 



426 THE TERPENES. 



9. GUAIOL, C^ 

The sesquiterpene alcohol obtained by Schimmel & Co. 1 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 fe called guaiol or champacol 
according to its source, has been investigated by Wallach and 
Tuttle. 2 

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^. 

East Indian sandalwood oil consists chiefly of a mixture of two 
sesquiterpene alcohols, C^H^OH, which are called a- and ^9-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, 3 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, [01]^= 1.2. Its acetate boils at 
308 to 310. 

/9-Santalol, C 15 H 25 OH, resembles its isomeride, boils at 309 to 
310, has the sp. gr- 0.9868 at 0, and [a\ D = 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. 

sGuerbet, Compt. rend., 130, 417 and 1324; Soden and Muller, 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 43. 



SANTALIC ACID. 427 

with dehydrating agents, are converted into two isomeric sesqui- 
terpenes, a- and fi-isosantalene, C 15 H 24 . These compounds are 
colorless liquids, having an odor of turpentine ; the a-isosantalene 
boils at 255 to 256, and has [o]^ = + 0.2, while the /3-deriv- 
ative boils at 259 to 260, and has [a\ D = + 6.1. 

a-Santalene, C 15 H 24 , boils at 252 to 252.5, has the sp.gr. 
0.9134 at 0, and [] jD = 13.98. When heated in a closed 
tube with glacial acetic acid at 180 to 190, it forms an acetate, 
C 15 H 24 C 2 H 4 O 2 , boiling at 164 to 165 (14 mm.). When dis- 
solved in ether and treated with dry hydrogen chloride, it forms 
a dihydrochloride, C 15 H 24 2HC1, which decomposes on distillation 
in vacuum ; its specific rotatory power is [a]^ = + 6. 

a-Santalene forms a nitrosochloride, C 15 H 24 NOC1, 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. 

/9-Santalene, C 15 H 24 , boils at 261 to 262, has the sp. gr. 
0.9139 at 0, and the rotatory power, [a] D = 28.55. Its 
acetate, C 15 H 24 C 2 H 4 O 2 , boils at 167 to 168 (14 mm.); its dihy- 
drochloride, C 15 H 24 2HC1, is decomposed on distillation, and has 
the rotatory power []/> = + 8. 

^-Santalene yields a mixture of two nitrosochlorides, C 16 H M '- 
NOC1, 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 (/9-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 1 ). 

Santalal, C ]5 H 24 O. This substance has the properties of an 
aldehyde, and boils at 180 (14mm.); 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 15 H 24 O 2 , is a liquid, boiling at 210 to 212 
under 20 mm. pressure. 

1 Guerbet, Compt. rend., ISO, 417; compare Chapoteant, Bull. Soc. Chim., 
37 [II.], 303; Chapman and Burgess, Proc. Chcm. Soc., 1896, 140; Chap- 
man, Journ. Chem. Soc., 79, 134. 



428 THE TERPENES. 

Teresantalic acid, C 10 H 14 O 2 , 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 15 H 25 OH, is obtained. It is a colorless, viscous liquid, 
having a famt 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 []/>= + 27. When heated with phthalic anhy- 
dride at 110, it loses water and yields a sesquiterpene. 1 It is 
possible that amyrol, like santalol, may consist of two similar 
alcohols, having different rotatory powers. 

In a more recent publication, Soden 2 states that a-santalol is 
probably a sesquiterpene alcohol having the formula, CjjH^OH, 
and not C 15 H 25 OH ; it forms the chief constituent of " santalol " 
and East Indian sandalwood oil. /9-Santalol may also have the 
formula C 15 H 23 OH. 

11. GALIPOL, C 15 H 25 OH, AND GALIPENE, C 15 H 24 . 

According to investigations by Beckurts and Troeger, 3 the 
oil of angostura bark contains about fourteen per cent, of a sesqui- 
terpene alcohol, C 15 H 2 ,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 15 H 24 , 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 15 H 25 OH, AND CAPARRAPENE, C 15 H 24 . 

The acid-free oil obtained from the essential oil of caparrapi con- 
tains a sesquiterpene alcohol, caparrapiol, 4 which boils at 260 
(757 mm.); it has the specific gravity 0.9146, the refractive index, 
n ? = 1.4843, and the rotatory power, [a\ D = 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, 

' Soden, 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. 

"Beckurts and Troeger, Arch. Pharm., 235, 518 and 634; 236, 392; com- 
pare Beckurts and Nehring, Arch. Pharm., 229, 612; Herzog, Arch. Pharm., 
143, 146. 

'Tapia, Bull. Soc. Chim., 19 [III.], 638. 



ZINGIBERENE NITEOSITE. 429 

the refractive index, n^ = 1.4953, and a rotatory power, [a]^ = 
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 15 H 26 O 3 , which crystallizes in white needles, melts 
at 84.5, and has the specific rotatory power, [a\ D + 3. It is 
sparingly soluble in cold water, soluble in hot water, and readily 
soluble in alcohol. Its calcium salt, Ca(C 15 H 25 O 3 ) 2 -f 5H 2 O, crys- 
tallizes in needles, melting at 250 ; the silver, sodium, and am- 
monium salts are crystalline. 

13. ZINGUBERENE, C 15 H 24 . 

The sesquiterpene, C 15 H 24 , which is the chief constituent of the 
oil of ginger, has been studied by Soden * and by Schreiner and 
Kremers. 2 

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, n D = 1.49399, 
at 20, and the specific rotatory power, [a] D = 69 to 73.38 
(100 mm. tube). 

Zingiberene dihydrochloride, 2 C 15 H 24 - 2HC1, 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, 3 C 15 H 24 'NOC1, 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. 

Zingiberene nitrosite, 3 C 15 H 24 *N 2 O 3 , 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. 

JH. von Soden and Rojahn, Pharm. Zeit., Ij5, 414. 
*Schreiner and Kremers, Pharm. Arch., 4, 141 and 161. 
'Schreiner and Kremers, Pharm. Arch., If, 161. 



430 THE TERPENES. 

Zingiberene nitrosate, C 15 H 24 'N 2 O 4 , 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 15 H 24 , FROM THE OIL OF 

CITRONELLA. 

According to Schimmel & Co., 1 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, n^ = 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 2 suggested a classification of 
the sesquiterpenes according to which these hydrocarbons, C 16 H M , 
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 III. Dicyclic sesquiterpenes having two double linkages. 
This class embraces most of the sesquiterpenes, including cadinene, 
caryophyllene and probably humulene. 

i Schimmel & Co., Semi-Annual Report, Oct., 1899, 23. 
*Schreiner and Kremers, Pharm. Arch., 4> 141. 



METATEREBENTENE. 431 

Group IV. Tricyclic sesquiterpenes having one double linkage. 
Clovene belongs to this group. 

Group V. 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., IV. 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, 1 and in the polymerization- 
products of valeryleue, 2 C 5 H g . Many ethereal oils also contain 
sesquiterpenes of an unknown nature. 

DITERPENES, C 20 H 32 . 

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 s or phosphoric anhydride 4 on oil of turpentine, and also by 
heating turpentine oil with benzoic acid, 5 and by the distillation 
of colophonium. 6 It is an oily, viscid liquid, 4 boils at 318 to 
320, and unites with hydrogen chloride, producing a very un- 
stable compound. 

Metaterebentene 7 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. 

ifiouchardat, Bull. Soc. Chim., 24, 108; compare Himly, Ann. Chem., 27, 
40; Williams, Jahresb. Chem., 1860, 495. 

'Bouchardat, Bull. Soc. Chim., 33, 24; Reboul, Ann. Chem., US, 373. 

"Deville, Ann. Chem., 37, 192. 

Seville, Ann. Chem., 71, 350. 

sBouchardat and Lafont, Compt. rend., 113, 551; Ber., 1891, 904, Rcf. 

6 Riban, Ann. Chim. Phys. [5], 6, 40; Armstrong and Tilden, Ber., 1879, 
1755. 

'Berthelot, Ann. Chim. Phys. [3], 39, 119. 



432 THE TERPENES. 

Dicinene 1 is obtained by the action of phosphoric anhydride on 
wormseed oil ; it boils at 328 to 333. 

Diterpilene 2 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 20 H 32 -HC1. 

Paracajeputene 3 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 4 is obtained by heating terpine hydrate with phos- 
phoric anhydride or hydriodic acid ; it is a 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-reain 
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 5 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, 
ft-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- 



and Stiircke, Ber., 1894, 1973. 

zLafont, 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. 

"Schmidt, Jahresb. Chem., 1860, 481. 

*Berkenheim, Ber., 1892, 686. 

sVesterberg, Ber., 20, 1242; 23, 3186; 24, 3834 and 3836. 



TRITERPENES. 433 

lization from petroleum ether or benzene. Pure a- and /9-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] D = + 91.59. 

/9-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\ D = + 99.81. 

The acetates of a- and /9-amyrin have already been men- 
tioned. 

Both a- and /9-amyrin are apparently secondary alcohols. 
When oxidized with chromic acid, they yield the corresponding 
ketones (or, possibly, aldehydes), a- and j3-amyrone, which, on treat- 
ment with hydroxylamine, are readily converted into oximes, 



en a- or /9-amyrin is dissolved in petroleum ether and 
treated with phosphorus pentachloride, a- or fi-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 /9-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^C^OCOCHg) ; this is converted into oxy-a-amyrin, 
C 30 H 47 O(OH), by hydrolysis. The analogous compound of the 
/9-series has not been isolated in a condition of purity (Vester- 
berg 1 ). 

The properties of a- and /9-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. These colors 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. 

JVesterberg, Ber., 24, 3836. 

28 



434 



THE TERPENES. 



According to O. Hesse/ /3-amyrin occurs as the palmitic acid 
ester in the wax obtained from Trujillo coca and Java coca. 

Palmityl-/9-amyrin, C 46 H 80 O 2 , melts at 75, and has the specific 
rotatory power, [a]^ = + 54.5. 





o-Series. 


/3-Series. 


Amyrin, CjoH^OH. 


Melting point, 181 to 


Melting point, 193 to 




181.5; slender needles ; 


194; slender needles; 




one part of a-amyrin 


one part of /3-amyrin 




dissolves in 21.36 parts 


dissolves in 36.44 parts 




of 98.3 per cent, alcohol 


of 98. 3 per cent, alcohol 




at 19 to 19.5. 


at 19 to 19.5. 


Amyrin acetate, 


[a] B =+91.6. 
Melting point, 221; 
large plates. 


Melting point, 236; 
long prisms. 




[a] w = + 77.0. 


[a]0 = -f- 78.6. 


Amyrin benzoate, 


Melting point, 192; 


Melting point, 230; 


C TO H 49 OCOC 6 H 5 . 


needles or flat prisms. 


leaflets. 


Bromoamyrin, 


Melting point, 177 to 


Melting point, 182 to 


CjoH.gBrOH. 


178; slender needles. 


186 (?); gelatinous. 


Bromoamyrin acetate, 


Melting point, 268; tab- 


Melting point, 238; 


C 80 H 48 BrOCOCH s . 
Amyrilene, CsgH^, pre- 


lets or flat prisms. 
Melting point, 135; very 


prisms. 
Melting point, 175 to 


pared by means of phos- 
phorus pentachloride. 


sparingly soluble in al- 
cohol; crystallizes from 
ether in splendid, thick, 


1 78 ; crystallizes from 
benzene in long, slender, 
rhombic prisms. 




rhombic prisms, and 


a :b:c = 0.91655:1 : 




sometimes separates in 


0.54032. 




sphenoidal hemihedral 


[a] = -1-111. 3. 




crystals. 






Axial ratio, 






a : 6 : c = 0.66733 : 1 : 






0.40489. 




Levo-a-amyrilene, 


Melting point, 193 to 




C 30 H 48 , prepared by 


194 ; sparingly soluble 




means of phosphoric 


in ether, more readily 




oxide. 


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: 6 :c = 0. 789:1:0.505. 






[a] D = 104.9. 





'Hesse, Ann. Chem., 271, 216. 



TETRATEREBENTENE HYDROCHLORIDE. 



435 



a-Series. 



0-Series. 



Amyrone, CjoH^O. 



Amyronoxime, 



Oxyamyrin, 
C 80 H 17 0(OH)+2H 3 0. 



Oxyamyrin acetate, 



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, 233 to 
234 ; needles, readily 
soluble in hot benzene, 
sparingly in alcohol 
and ether, insoluble in 
petroleum ether and pot- 
ash. 

Melting point, 207 to 
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] D = + 108.6. 

Melting point, 278 ; 
crystallizes from ben- 
zene in six-sided plates, 
which belong to the 
sphenoidal - hemihedral 
division of the ortho- 
rhombic system. 



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. 



Melting point, 262 to 
263 ; leaflets, insoluble 
in alcohol, sparingly 
soluble in ligroine and 
ether, quite readily in 
hot benzene. 



Melting point, 240 (?). 



TETRATERPENES, C^. 

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 1 ). It is 
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 10 H 16 , when it is distilled. 

Tetraterebentene hydrocbloride,C 40 H 64 .HCl,is formed when hydro- 
chloric acid gas is led over pulverized tetraterebentene. The dihy- 
drochloride, C 40 H 64 '2HC1, 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 1 ). 

1 Riban, Ann. Chim. Phys. [5], 6, 40. 



INDEX. 



Absinthol = Thujone, 225 

Acetaldehyde, 398 

Acetic acid, 71, 129, 158, 200, 224, 264, 265, 

277 

Acetone, 218, 243, 392, 406 
Acetoxylene, 158 

oxime, 158 
Acetyl bornylamine, 341 

carvomenthylamine, 358, 865 
dihydrocarvylamine, 358 
o-Acetyl-jS, /3-dimethyladipic acid, 403 
hydrogen ethyl ester, 403 

semicarbazone, 403 
Acetyl fencholenamine, 352 
fenchylamine, 349 
menthonylamine, 413 
d- Acetyl menthylamine, 371 
I- Acetyl menthylamine, 368 
Acetyl neobornylamine, 345 

pinylamine, 337 
Acid, CrHioOs, 183 

dibromide, 183 
, 47 
s, 196 

CsHuOj, 214 
C 9 Hi 6 O4, 289 
CioHi 6 O2, 246 

amide of, 246 
CioHieO*, 233 
CioHisOs, 401 
CioHuOi, 264, 406 
CioHisOsN, 64 
CioHiO4N, 306 
s, 423 
s, 429 

calcium salt of, 429 
Acid a-camphylamine oxalate, 346 
Acrolein, 399 

Addition-product of cineole and iodol, 326 
Alcohol CioHwOH, 316 
Aldehyde, CioHisO, from camphene gly- 

col, 151 

from myrcenol, 378 
oxime of, 378 
semicarbazone of, 378 
Allolemonal, 405 
Amidocamphene, 66 
camphor, 152 

2-hexahydrocymene = Carvomenthyl- 
amine, 290, 364 
menthol, 306 
menthone, 241, 305 
menthonoxime, 306 

hydrochloride, 306 
phellandrene, 111, 374 
hydrochloride, 375 
mercuriochloride, 375 
platinochloride, 375 
sulphate, 375 



437 



Amidoterebentene, 338 

hydrochloride, 339 
oxalate, 339 
platinochloride, 339 
sulphate, 339 

p-Amidothymol, 188, 189, 211 
Amine, CgHisN^, 232 

derivatives of, 232 
C 9 HnNH2, 232 

carbamide of, 232 
CioHnNHs, 115 

derivatives of, 115 
CioHiaON, 181 
CioH] 5 O.NH 2 , 115 
CioHziON, 352 
CioHieBr.NHOH, 270 

nitroso-derivative of, 270 
CioHnBrz.NHOH, hydrobromide, 

270, 271 
C2oH35ClN 2 , 302 

hydrochloride, 302 
Aminodecoic acid, 289, 308 
Ammonium a-fencholenate, 164 
a-Amyrilene, 433 
/3-Amyrilene, 433 
/-a-Amyrilene, 433 
Amyrin, 432 

derivatives, table of, 434 
o-Amyrin, 433 
acetate, 432 
benzoate, 434 
^-Amyrin, 433 
acetate, 432 
benzoate, 434 
palmitate, 434 
Amyrol, 428 
a-Amyrone, 433 
/3-Amyrone, 433 
o- and j8-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 Pleissner's " hydrated 
pulegonoxime," CioHi9NO2, and its 
derivatives, 240 

Beckmann's reagent, 113 

Benzoyl bornylamine, 341 
campholamine, 353 



438 



INDEX. 



Benzoyl a-camphylamine, 346 

carvoxime, 191 
i-Benzoyl-a- carvylamine, 356 

/3-carvylamine, 356 
Benzoyl-a-d-carvylamine, 355 

o-1-carvylamme, 356 

0-d-carvylamine, 356 

p-1-carvylamine, 356 

carylamine, 359 

dihydrocarvylamine, 358 

dihydroeucarvylamine, 360 

dipentene nitrosochloride, 96 

fencholenamine, 352 

fenchylamine, 349 

hydrochlorpcarvoxime, 192 

limonene nitrosochloride, 76 

menthylamine, tertiary, 374 

neobornylamine, 345 

pinylamine, 338 

pulegonamine, 363 
Benzyl bornylamine, 342 
hydrochloride, 342 
methiodide, 342 
platinochloride, 342 

dihydrocarveol, 211 

fenchylamine, 350 

hydrochloride, 350 
mtroso-deriv_ative of, 350 
platinochloride, 350 
Benzylidene bornylamine, 342 
hydrochloride, 342 
platinochloride, 342 

carvone, 193 

dihydrocarvone, 211 

dihydrocarvoxime, 211 

dihydroisocamphor, 252 

eucarvone, 200 

feuchylamine, 350 

hydrochloride, 350 

menthone, 306 

hydrobromide, 306 
hydrochloride, 306 

menthonoxime, 306 

menthylamine, 306 
<i-Benzylidene menthylamine, 372 
/-Benzylidene menthylamine, 369 
Benzylidene menthyl carbamate, 312 

nppinone, 54 

pinylamine, 338 

pulegone, 342 
Benzyl menthol, 306 

menthone, 307 

menthonoxime, 307 

menthylamine, 307 

pulegol, 243 

Bismtroso-4-bromotetrahydrocarvone, 208 
Bisnitrosocarvone, 209, 220 

menthone, 304 

pulegone, 342 

pulegonoxime, 342 

tetranydrocarvone, 288 
Bispulegone, 243 
Borneo-camphor, 142 
Borneol, 141 

bromal derivative of, 144 

chloral derivative of, 144 

derivatives, table of, 149 
Bornyl acetate, 143 
Bornylamine, 135, 340, 343, S44 



Bornylamine, acetyl derivative of, 341 

acid sulphate, 341 

benzoyl 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 
Bornyl butyrate, 143 

carbamide. 342 

methyl derivative of, 342 
phenyl derivative of, 342 

chloride, 144 
Bornylene, 121 

oxidation of, 121 
Bornyl esters, table of, 143 

ethyl ether, 144 

formate, 143 

iodide, 40, 145 

methylcarbamide, 342 

methylene ether, 144 

methyl ether, 143 

phenylcarbamide, 342 

phenylthiocarbamide, 342 

phenylurethane, 144 

prppionate, 143 

thiocarbamide, 342 

valerate, 143 

xanthic acid, 144 
Brominated lactone, 164, 166 
Broinoamyrin, 433, 434 

acetate, 433, 494 
Bromocamphene, 62 
2-Bromocymene, 184 
Brompfenchone, 159 

nitrocamphane, 66, 123 
& - Bromo-a-oxyisopropyl hexenoic acid, 

332 
Brompp_ernitrosocamphor, 153 

pinic acid, 56 
l-Bromo-A 4 < 8 )-terpene, 93, 271 

nitrosobromide, 93, 271 

A (8)-terpene, 93 

nitrosobromide, 93 
Bromotetrahydrocumic acid, 53 
Butyryl fenchylamine, 349 
d-Butyryl menthylamine, 371 
Z-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 
Camphane = Dihydrocamphene, 123 
Camphenamine, 253 
Camphene, 56, 341 

alcoholate, 65 

aldehyde, 60, 65 



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 

hydriodide, 61 

hydrobromide, 61 

hydrochloride, 61 

nitrates, 65 

nitronitrosite, 60 

nitrosite, 60 

oxidation of, 63 

o-Camphene phosphorous acid, 59 
/3-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 
Camphenilone, 61, 64 

alcohol, 64 

alcohol, chloride of, 64 

oxime, 64 

semicarbazone, 64 
Camphenol = Carvenone, 62 
Z-Camphenol = Borneol, 142 
Camphenone, 152 

dibromide, 153 

hydrobromide, 153 

monobromo-derivative of, 153 

oxime, 153 

pernitroso-derivative of, 153 

dibromide = Dibromoperni- 

trosocamphenone, 153 
Camphenylnitramine, 251 
Camphenylpne = Camphenilone, 61, 64 
Camphocenic acid, 64 
Camphocenic nitrile, 64 
Camphoceonic acid, 64 
Camphoic acid, 63 
Camphol alcohol, 152 
Campholamide, 141 
Campholamine, 141, 353 

benzoyl derivative of, 353 

hydrochloride, 152, 353 

nitrate, 353 

platinochloride, 353 
a-Campholenamide, 136 
/3-Campholenamide, 139 
o-Campholenamidoxime, 136 
Campholene, 137, 140, 353 
o-Campholenic acid, 136 
0-Campholenic acid. 139 
a-Campholenic amide, 136 
0-Campholenic amide, 139 
a-Campholenonitrile, 135, 346 
/3-Camphplenonitrile, 139, 347 
Campholic acid, 141, 353 
Campholic amide, 141 
Camphol, instable = Isoborneol, 146 
Campholonic acid, 139 
Campholonitrile, 141, 353 
Camphol, stable = Borneol, 146 
Campholyl phenylthiocarbamide, 353 
Camphopyric acids, 64, 69, 71 
Camphopyric anhydride, 63, 64, 69, 71 
Camphor, 133 



Camphor, artificial = Pinene hydrochlor- 
ide, 38 

condensation-products of, 141 

derivatives, optical properties of, 150 
Camphor dioxime, 135 
Camphor, oxidation of, 134 

liquid, 83 

Camphoric acid, 64, 134 
Camphoronic acid, 134 
Camphproxime ; 135 

action of nitrous acid on, 135 

anhydride = a-Campholenonitrile,1^5, 
346 

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 
Camphydrene = Dihydrocamphene, 39, 

iZo 

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 
Caoutchin, 85 

hydrate = Terpineol, 258 
Caoutchouc, 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, 29S 
Carvanone = Tetrahydrocarvone, 219, 291, 

293 

Carvene = d-Limonene, 71, 72 
Carvenol = Carvenone, 62, 219, 293 
JM-Carvenolic acid, 182 



440 



INDEX. 



i-J-Carvenolic acid, 182 
Carvenolic acid, inactive, 182 
Carveuolic acids, 182 

dibrornides of, 183 

monobasic acid, C 7 H 10 O 4 , from, 

183 
Carvenolides, 182 

dibromides of, 182 
Carvenone, 62, 134, 207, 216 

benzylidene derivative of, 218 
uitroso-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 
dihydrobroinide, 104 
dihydrochloride, 104 
ortho-, 104 
pseudo-, 104 
Carvol = Carvone, 178 
Carvomenthene, 124, 292 
hydrobromide, 125 
hydrochloride, 125 
Carvomenthol = Tetrahydrocarveol, 291, 

365 

tertiary, 293, 316 
Carvomenthone=Tetrahydrocarvone,238, 

254, 287 

Carvomenthyl acetate, 293 
Carvomenthylamine = Tetrahydrocavyl- 

amine, 111, 290, 364 
acetyl derivative of, 365 
formyl derivative of, 365 
hydrochloride, 365 
platinochloride, 365 
tertiary, 373 

benzoyl derivative of, 374 
chloroaurate, 374 
hydrochloride, 374 
platinochloride, 374 
Carvomenthyl bromide, 293 

tertiary, 317 
carbamide, 365 
chloride, 293 
iodide, tertiary, 316 
phenylcarbamide, 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 

peutabromides, 183 
phenylhydrazone, 184 
reduction products of, 194 
semicarbazones, 193 
semioxamazone, 193 



Carvone sodiumjdihydrodisulphonate, 193 
semicarbagone, 193 

tetrabromides, 183 

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 

carbanilido-, 191 

derivatives of, 184 

hydrobromide, 192 

hydrochloride, 191 

beuzoyl derivatives of, 192 
Carvoxime, inactive, 190 

iso- 190 
Carvylamines, 354, 355, 356 

derivatives 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 

benzylanrines, 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, CioHuCl, 208, 223 
a-Chlorocamphene, 62 
hydrochloride, 62 
sulphonic chloride, 62 
Chlorocamphydrene, 39 
3-Chlorocymene, 298 
2-Chlorocymene, 184 
Chlorodihydrocymene, 298 

fenchene, 159 

Ehosphoric acid, 158 
one hydrochlorides, 158 
ketones, 281, 288 



INDEX. 



441 






Chloromethyl menthyloxide, 311 
2-Chloropulegone, 242 
3-Chloro-A 2 <* : 8)-terpadiene, 243 

tetrabromide, 243 
Chlorotetrahydrocymene, 298 
Cholesterine reagent, 433 
Cinene, 85 
Cinenic acids, 332 

derivatives of, 332 
Cineole, 323 

addition-product with iodol, 324, 

326 

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 
anihde, 328 
diethylamide, 328 
ethyl ester, 327 
methyl ester, 327 
para-toluidide, 329 
phenylhydrazide, 329 
piperidide, 328 

silver salt of, 328 
Cinnamic aldehyde, 399 
Cinogeuic acid, 332 
Citral = Geranial, 396 
a = Geranial a, 400 
b = Geranial b t 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 
/3-naphthocinchonic acid, 411 

hydrochloride, 411 
/3-naphthyl quinoline, 41 1 
normal sodium bisulphite, 410 
oxidation of, 410 
oxime, 412 
phosphoric acid, 411 
semicarbazone, 412 
sulphonic acids, 410 
Citronellainide, 412 
Citronella pimelic acid, 412 
Citronellic acid, 401, 410, 412 

dioxy-, 412 

Citronellol, 389, 394, 410 
acetate, 396 
chlorinated phosphoric acid ester, 395 



Citronellol diphenylurethane, 396 

formate, 396 

hydrogen phthalate, 395, 396 

oxidation of, 396 
Citronellone = Citronellal, 409 
Citronellonitrile, 412 
Citronellylidene cyanoacetic acid, 411 
Clovene, 417, 418, 421 
Coca wax, 434 
Colophene, 431 

hydrochloride, 431 
Colophouium, 35, 87 
Compound, CsHgCl.OH, 33 

C7HioOiN2, 111 

CioHieO or CioHisO, 343 

CioHieOa, 159 

CioHisBr, 159 

CioHzsOs, 293 

CioHisCb, 391 

CioHsOBre, 299 

CioHi 6 N 2 O2, 193 

CioH 2 oN 2 O2, 217 

CioHuBr(OCHs), 197 

CioHisO.HsPO*, 324 

CioHnO2.OC2H 5 , 401 

CioHi 6 .2CrO2Cl2, 65 

CuHisO, 41 

CuHioNOsCl, 98 

CnHnNO, 169 

CizH22NO2Cl, 98 

Ci2H 2 oBrOs, 279 

CieHjsCIO*, 194 

CaoHaiO, 248 

CaoHsiOa, 254 

CaoHasN.HBr.Bn, 343 

C2iH24O2, 200 

Ca4HaO2, 218 
Condensation-product, CnHisO, 83, 

98 
Ci6H 27 NO2, 351 

C24H28O2, 290 

of eucarvone and benzaldehyde, 

200 

Copal resin, 35, 87 
Coriandrol = Dextro-linalool, 383 
m-Cresol, 246 
Cubeb camphor, 424 
Cubebene, 424 
Cumic acid, 122 
Cuminaldehyde. 122 
Cuminyl 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, JflS, 404 
Cycloheptylenamine, formyl derivative 

of. 244 

Cyclolinalolene, 380, 130 
Cymene, 85, 160, 398 
Cymylhydroxylamine, 189, 190 



442 



INDEX. 



Decenoic acid = Menthonenic acid, 28, 

&O QAQ 
OUZ, O\JO 

Decoic acid. 303 

.amide, 303 
Dextro-linalool, 383 

menthone, 315 

Dextrorotatory menthone, 297 
Diacetate of glycol, CioHi8(OH)2, 391 
Diamidophellandrene, 375 
hydrochloride, 376 
platinochloride, 376 
salts of, 376 
Diamine, 306 

hydrochloride, 306 
Diaterpenylic acid, 196 
Diaterpeuylic lactone = Terpenylic acid 

196 

Diazo-camphor, 152 
Dibasic acid^ CgHieCU, 295 
Dibenzoyl 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-l-ol, 270 

acetate, 93, 270 

1, 8-Dibromotetrahydrocarvone, 221 
Dicarboxylic acid, CiiHisO*, 169 
Dicarvelones, 194, 195, 212 
dihydrobromides, 195 
oximes, 195 

acetyl derivatives of, 195 
phenylhydrazones, 195 
Dichloride from fenchyl alcohol, 173 
o-Dichlorocamphene, 62 
Dichlorocarvone, 183 
Dichlprodipentene, 91 
dibromide, 91 
dihydrochloride, 91 
hydrochloride, 90 
nitrolanilide, 91 

piperidide, 91 
nitrosochloride, 91 
Dichlorotetrahydrocarvone, 221 
Dicinene, 432 

Diethyl hexamethylene, 132 
alcohol, 132 
iodide, 132 
ketone, 132 

Dieucarvelone, 196, 200 
isomeride of, 196 
oxime, 196 

phenylhydrazone, 196 
Difenchone, 170 
Difenchyloxamide, 349 
thiocarbamide, 349 



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 
hydrobromide, 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, 857 
oxalate, 358 
sulphate, 358 
Dihydrocarvyldiamine, 358 

derivatives of, 358 

Dihydrocarvyl methyl xanthate, 213 
phenylcarbamide, 358 
phenylthiocarbamide, 358 
phenylurethane, 213 
Dihydrochlorodipentenes, 89 

dichloride, 91 

Dihydrocuminyl alcohol, 122 
Dihydrocumic acid, 54 
Mhydrocymene, 22, 27 
Mhydrodicamphene, 123 
Dihydroencarveol, 200, 223, 2% 
acetate, 224 
chloride, 224 
Dihydroeucarvone, 223 

nitroso-derivative of, 223 
oxidation of, 223 
semicarbazone, 223 
)ihydroeucarvoxime, 223 

hydriodide, 22S, 293, 359 
Dihydroeucarvylamine, 223, 359 
benzoyl derivative of, 360 
hydrochloride, 360 
platinochloride, 360 
Dihydroeucarvyl phenylcarbamide, 360 

thiocarbamide, 360 
ihydrofencholene, 164 
ihydrofencholenamide, 167 
ihydrofencholenic acid, 167 
Mhydrofencholenic lactam = ft- Isofen- 
ehonoxime, 168 




INDEX. 



443 



Dihydrofencholenonitrile, 167 
Dihydroisocamphor, 252 

acid sodium sulphite, 252 

benzylidene derivative of, 252 

semicarbazone, 252 
Dihydroisothujol = Thujamenthol, 236, 

96 
Dihydromyrcene, 379 

cyclo-, 379 

diketone from, 379 

keto-glycol from, 379 
Dihydropseudocumene, 231 
Dihydroxylene, meta-, 330 
Diisonitroso-methyl-cyclohexanone, 242 

diacetate, 242 
Diisoprene, 85 
Diketone, CH U O 2 , 211, 212 
dioxime of, 211, 212 
semicarbazone of, 212 

CioHuCb, 193 
1, 3-Diketone, CioHi 6 O2, 310 

dioxime of, 310 
Dimentholic formal, 310 
Dimenthyl, crystalline, 313 

liquid, 313 

methylal 310 

0, a-Dimethyl adipic acid, 402 
/3, /3-Dimethyl adipic acid, 402 
gem-Dimethyl adipic acid, 294 

1, 2, 4-Dimethyl ethyl benzene, 120 
Dimethyl fenchylamine hydriodide, 349 
a, a-Dimethyl glutaric acid, 403 

2, 6-Dimethyl heptan-5-onic acid, 218 

oxhne, 218 
Dimethyl heptenol 392 

isopropyl butylene oxide, 232 
S-Dimethyl laevulinic acid, 231 
w-Dimethyl laevulinic acid, 231 

oxime, 231 
3- or w-Dimethyl laevulinic methyl ketone, 

230, 233 
oxime, 231 

Dimethyl malonic acid, 158, 163, 294 
2, 6- octadiene-2, 6 - acid-8 = Geranic 

acid, 407 

2, 7-ol-6 = Linalool, 383 
2, 6-al-8 = Geranial, 407 
2, 6-ol-8 = Geraniol, 383, 392 
2, 6-Dimethyl octane-2, 8-ol, 394, 413 

3-onoic acid. 310 
Dimethyl-2, 6-octene-2-al-8 = Citronellal, 

410 

ol-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 
tricarballoylformic acid, 55 
tricarballylic acid, 51, 55, 64, 158 
gem - Dimethvl trimethylene - 1, 2-dicar- 

boxylic acid, 222 
Dinitroeudesmole, 286 
Diosphenol, 315 



Dioxime, C9Hu(NOH)2, 211 

CioHu(NOH) 2 , 193 
Dioxycamphoceanic acid, 64 
Dioxycitronellic acid, 412 
a-Dioxydihydrocampholenic acid, 136, 138 
/3-Dioxydihydrocampholenic acid, 139 
Dioxydihydrocyclogeranic acid, 402 
Dipentene, 85^ 213, 358, 377 

derivatives, table of, 100 

dichloride, 91 

dihydriodides, 94 

dihydrobromides, 91 

dihydrochlprides, 89 

hydrochloride, 89 

nitrolamines, 96 
a-Dipentene nitrolanilide, 96 

nitrosp-derivative of, 97 
0-Dipentene nitrolanilide, 97 

nitrosp-derivative of, 97 
Dipentene nitrolbenzylamine, 97 

nitrolpiperidide, 96 
0-Dipentene nitrolpiperidide, 96 
Dipentene nitrosochforides, 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 

5-chloro-<*-methoethylol-5-hexoate,332 

cineolic ester, 327 

hydrogen cineolate, 327 

isobornyl 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 

dmydrobromide, 120 



Fenchelene, 120 
Fenchene, 66, 171 
ZM-Fenchene, 67 
Z>-Z-Fenchene, 67 
jW-Fenchene, 67 
2i-/-Fenchene, 67 



444 



INDEX. 



Fenchene alcoholate, 68 

dibromide, 68 

hydriodide, 68 

hydrobromide, 68 

hydrochloride, 68 

oxidation products of, 68 
Fenchenole, 177 

hydrobromide, 177 
Fenchimine, 16_6 

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 
/3-Fencholenamide, 165 
Fencholene alcohol = Fencholenyl alco- 
hol, 176, 352 
Fencholenamine, 162, 163, S51 

acetyl derivative of, 352 

benzoyl derivative of, 352 

nitrate, 352 

oxalate, 352 

sulphate, 352 

Fencholenfurfuramide, 352 
a-Fencholenic acid, 159, 163, 166 

amide = a-Isofeuchonoxime, 162 
hydrobromide, 164 
hydrochloride, 164 
salts of, 164 
sodium salt of, 164 
/3-Fencholenic acid, 165 
/3-Fencholenic acid hydrobromide, 166 
salts of, 166 
sodium salt of, 166 
a-Fencholenonitrile, 161, 165, 351 
p-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 
Fenchyl alcohol, 170 
D-Z-Fenchyl alcohol, 67, 171 
Z-d-Fenchyl alcohol, 67, 171 
Fenchyl 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 

fenchylcarbauiate, 348 

formyl derivative of, 347, 348 

hydriodide, 348 

hydrochloride, 348 

o-methoxybenzylidene derivative of 
351 

_p-methoxybenzylidene derivative of, 
351 

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-Fenchjl chloride, 173 
ZM- Fenchyl chloride, 173 
Fenchyl chloride, secondary, 173 
tertiary, 67, 172 

formate, 171 

hydrogen phthalate, 172 

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 bornylaminCj 341 

carvomenthylamine, 365 

dihydrocarvylamine, 357 
d-Formyl menthylamine, 371 
- Formyl menthylamine, 368 

neobornylamine, 345 
Furfuro-pinylamine, 338 

-fencholenamine, 352 

G 

Galipene, 428 

hydrobromide, 428 
Galipol, 428 
Geranial, 377, 396, 405 _ 

acid sodium sulphite, 397 

anilide, 399 

-(citral-) a, 400 

a, semicarbazone, 400 
6,401 

b, naphthocinchonic acid, 401 
6, oxime, 401 

6, semicarbazoue, 401 
dihydrosulphonic acid derivatives,398 
Geranialidene bisacetylacetone, 405 
cyanoacetic acid, 404, 405 



INDEX. 



445 



6-Geranialidene cyanoacetic acid, 405 
Geranial-P-napthocinchonic acid, 399 

hydrochloride, 399 
Geranial, oxidation of, 405, 406 
oxime, 400 

phenylhydrazone, 399 
potymeride of, 405 
semicarbazones, 400 
sodium bisulphite, normal, 398 
hydrosulphonate, 398 
tetrabromide, 398 
Geranic acid, 401 

o- and /3-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, S91, 395 
diphenylurethane, 393 
tetrabromide, 393 
hydrogen phthalate, 390, S93 
silver salt of, 393 
tetrabromide, 393 
succinate, 390 
iodide, 391 

phenylhydrazone, 399 
Geronic acid, 402, 404, 405, 408 

semicarbazone, 404 
Glycerol, C 9 Hn(OH)3, 233 
Glycol, C 5 H 8 Br2(OH)2, 32 
CioHi 6 (OH) 2 , 263 
diacetate, 263 
CioHi8(OH) 2 , 207, 214, 220, 391 

diacetate, 214, 391 
CioHzoCh, crystalline, 315 

liquid, 315 
Gonorol, 426 
Guaiol, 426 

acetate, 426 
Guttapercha, distillation of, 31 



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 

Homocainphoric acid, 133 

Homolimonene, 211 

Homoterpenoylformic acid, 54 
oxime of, 55 

Honioterpenylic acid, 54, 55 

Humulene, 421 

bisnitrosite, 422 
isonitrosite, 422 
nitrolamines, 4^2, 423 
nitrolbenzylamine, 422, 423 
hydrochloride, 422 



Humulene nitrolpiperidide, 422, 
hydrochloride, 422 
platinochloride, 422 
nitrosate, 422, 423 
nitrosite, 422, 423 
nitrosocnloride, 422, 423 
Hydrated pulegonoxime = Pulegone hy- 

droxylamine, 239, 240 
acetyl derivative of, 241 
benzoyl derivative of, 241 
hydrochloride, 241 
oxalate, 241 
Hydrazocamphene, 65 
Hydriododihydroeucarvoxime, 223, 293, 

359 

Hydriodofenchonoxime anhydride, 162 
Hydro-aromatic acids, behavior of, 215 
Hydrpbromocarvone, 180, 198 
dibromide, 181 
keto-amine of, 181 
phenylhydrazone, 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, CeHie, 245 

nitrosochloride of, 245 
CioHu, 358 
CioHie, 379 
CioHis, 130, 380 
CioH 2 o, 131, 3l5 
CioHsa, 379 
CisHzs, 416 
CnH22, 211 
CsoHso, 421 
Hydrocarbons, CioHis, 123 

CioH20, 130 

Hydrochlorocarvone, 180 
phenvlhydrazone, 180 
Hydrochlorocarvoxime, 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 
HydrochlorpHmonene, 80 
nitrolamines, 82 
anilide, 82 
benzylamine, 82 
nitrosate, 81 
nitrosochloride, 81 
Hydrochloronitrosodipentene ethyl ether, 



446 



INDEX. 



Hydrochloronitrosodipentene methyl 

ether, 98 

Hydrochloropulegone, 239 
Hydrocyanic acid, 158 
Hydroxycamphene, 66 
Hydroxycamphoronic acid, 51 
Hydrpxylammocarvoxime, 192 

dibenzoyl derivative of, 192 

diphenylcarbamide, 193 

diphenylthiocarbamide, 193 

picrate, 192 



Inactive carvoxime, 96, 190 

menthol, 312, 315 

pulegone, 239 

Instable camphol = Isoborneol, 146 
lonone, commercial, 407 
o-Ionone, 407 

oxime, 407 

semicarbazone, 407 
/S-Ionone, 405, 408 

oxime, 408 

semicarbazone, 408 
Irone, 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 /3-methyl valeric acid = Oxy- 

menthyhc acid, 129, 310 
Isocamphenilanic acid, 65 
Isocamphenol, 171 
Isocamphenone, 153 

oxime, 153 
Isocamphol, 58, 146 
Isocamphopyric acid, 63 
Isocamphor, 166, 251 

bisnitrosochloride, 252 

dihydro-, 252 

oxime, 166, 252 

semicarbazone, 166, 252 

tetrahydro-, 252 
fl-Isocamphor, 253 

phenylurethane, 253 
Isocamphoranic acid, 52 
Isocarnphorenic acid, 52 
Isocamphorone, 139 
Isocamphoronic acid, 51, 55, 158 
Isocamphoroxime = a-Campholenamide, 

136 
Isocarveol = Pinocarveol, 201, 202 



Isocarvone = Pinocarvone, 201 
Isocarvoxime, 190 

benzoyl derivative of, 191 
carbanilido-, 191 
Isocedrol, 424 

benzoate, 424 
Isodihvdrocamphene, 124 
Isofencholenyl alcohol, 163, 176 
a-Isofenchonoxime, 162 
/3-Isqfenchonoxime = Dihydrofencholenic 

acid lactam, 163 
0-Isofenchonoxime, salts of, 163 
Isofenchyl alcohol, 68, 174 
acetate, 174 

derivatives, table of, 175 
formate, 175 
hydrogen phthalate, 175 
ketone from, 175 

alcohol from, 175 
oxime, 175 
phenylurethane, 175 
Isogeronic acid, 402, 403, 404, 408 

semicarbazone, 403, 404 
Isoketocamphoric acid, 51 
Isomenthol, 309, 314 
Iso-^-menthonoxime, 301 
Isomenthyl benzoate, 314 
Isomeric terpineol, m. p. 69 to 70 = 

A*(8)-Terpen-l-ol, 269 
m. p. 32 to 33 = A8(9).Terpen- 

l-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 
tetrabromide, 32 
a-Isopropyl glutaric acid, 252 
anhydride, 253 
anilide, 253 
5-Isopropyl heptan-2-onic acid, 288 

oxime, 288 

a-Isopropylidene-AY-hexenoic acid, 333 
j3-Isopropyl laevulinic acid, 236, 295 
Isopropyl succinic acid, 236, 237, 288, 

289 
Isopulegol, 247, 410 

acetate, 247 
Isopulegone, 247, 248 
a-Isopulegone, 249 
/s-Isopulegone, 248 



INDEX. 



447 



Isopulegone derivatives, table of, 250 

semicarbazones, 249 
Isopulegonoximes, 249 
Isosantalenes, 427 
Isoterebentene, 85 
a-Isotetrahydrocarvoxime, 289 
0-Isotetrahydrocaryoxime, 290 
Isothujaketonic acid, 236 
oxime, 236 
semicarbazpne, 236 
Isothujamenthonoxime, 294 
Isothujene, 119, 360 
Isothujolacetic acid, 235 
Isothujonej 157, 235 

oxidation of, 236 

oxime, 228, 285 

semicarbazones, 235 
Isothujylamine, 362 

hydrochloride, 362 

nitrate, 362 
Isothujyl carbamide, 362 

phenylcarbamide, 362 

phenylthiocarbamide, 362 
Isovaleric acid, 392 

E 

Keto-ainine, 181 

derivatives of, 181 
Ketodihydrocymenes, 22 
Ketohexahydrocymene, 19, 24 
-Keto-isocamphoronic acid, 55 
Keto-lactone, OioHieOs, = Methoethylhep- 

tanonolide, 263 
oxime, 264 
semicarbazone, 264 
= Methyl ketone of homoter- 

penylic acid, 221, 267 
CioHisOs, 48, 49, 52, 295 

oxime, 295 
Ketomenthone, 307 

oxime, 308 
Ketone, CioHuO, 212 

CioHieO, 155, 212, 253 

oxime, 253 
Ketone alcohol, CioHieOa, 47 

oxime, 47 
CioHnO.OH, 129 
acetate, 207 
oxime, 129 
phenylurethane, 129 
Ketone glycol, 212 

semicarbazone, 212 
Ketonic acid, CsHi^Os, 71 

derivatives of, 71 
C 9 Hi2O3, 403 

semicarbazone, 403 
CioHisOs, 294, 295 
oxime, 294 

semicarbazone, 294, 295 
Keto-oxydihydrocyclogeranic acid, 
402 

semicarbazone, 402 
Ketopentamethylenes, 133 
pinic acid, 39 

hydrazone, 39 
oxime, 39 

Ketotetrahydrocymenes, 20 
Keto-terpine, 209 



L 

Lactone, CrE^Os, 230 

CioHi 6 O2, 169, 246 
e-Lactone, CioHisOz, 300 

derivatives of, 300 
Lactonic acid, C7HioOt, 243 

CioHieOi, 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 
Z-Licarhodol, 405 

Liebermann's cholesterine reagent, 433 
Limonene, 71, 213 

chlpro-derivative of, 80 

derivatives, optical properties of, 85, 
86 

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 

nitrosochlorides, 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 

cyclo-, 380 
Linalool, 377, 381 

dextro- = Coriandrol, 383 

oxidation of, 386 

properties, table of, 382 

sodium salt of, 384 
Linalyl acetate, 386 

butyrate, 387 
d-Linalyl chloride, 386 
Linalyl chlorides, 385 
d-Linalyl iodide, 386 
Linalyl propionate. 387 

sodium phthalate, 384 

valerianate, 387 

M 

Masspyene, 34 
Matricaria camphor, 133 
Mentha camphor, 308 
Menthadienes, 24 
Meuthandiol-3, 8, 248 



448 



INDEX. 



Meuthane = Hexahydrocymene, 24, 130, 

131 

cis-Menthane-1, 2-dichlor-6, 8-diol, 40, 282 
Menthane, meta-, 131 . 
Menthan-2-ol = Carvomenthol, 291 

3-ol = 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(9)-Menthene-l, 2-diol, 263 

diacetate, 263 

A'-Menthene-e.S-diol = Pinole hydrate, 277 
A 6 -Menthene-2,8-diol = Pinole hydrate, 277 
Menthene glycol, 129, 323 
diacetate, 129 
monoacetate, 129 
terpene, CioHie, from, 129 
Menthene hydriodide, 314 

hydrobromide, 314 

hydrochloride, 313 

meta-, 130 

nitrolbenzylamine, 128 

nitrosate, 128 

nitrosochloride, 128 
A 6 -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 
Menthobisnitrosyhc acid, 304 
Menthocitronellal, 303, 409 

/3-naphthocinchonic 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, CioHttCl, 298 



Menthone, chloro-derivative, 

298 
dextro-, 315 
dextrorotatory, 297 
dibromo-derivative of, 299 
dicarboxylic acid, 307 
inactive, 297 
levorotatory, 297 
Menthonenic acid = Decenoic acid, 289 

302, 303 
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 
-Menthonoxime, 300 
d-Menthonoxime hydrochloride, 301 
Z-Menthonoxime hydrochloride, 300 
Menthonyl acetate, 394 

alcohol = Menthocitronellol, 393, 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 
p_latinochloride, 413 
Menthoximic acid, 304, 310 
Menthyl acetate, 311 
acetoacetate, 311 

phenylhydrazone, 311 
d-Menthyl allylthiocarbamide, 372 
d- (cis-) Menthylamine, 370 
I- (trans-) Menthylamine, 301, 368 
d- (cis-) Menthylamine, acetyl derivative 

of, 371 

benzylidene derivative of, 372 
butyryl derivative of, 371 
formyl derivative of, 370, 371 
hydriodide, 371 
hydrobromide, 371 
hydrochloride, 371 
o-oxjrbenzylidene derivative of, 372 
propionyl derivative of, 371 
I- (trans-) Menthylamine, acetyl deriva- 
tive of, 368 

benzylidene derivative of, 369 
butyryl derivative of, 369 
formyl derivative of, 368, 370 
hydriodide, 368 
hydrobromide, 368 
hydrochloride, 368 
nitrite, 368 

o-oxybenzylidene derivative of, 369 
propionyl derivative of, 369 
Menthylamines, 298, 365 

and derivatives, optical properties of, 
373 



INDEX. 



449 



Menthylamine, tertiary, 374 

benzoyl derivative of, 374 
chloroaurate, 374 
hydrochloride, 374 
platinochloride, 374 
Menthyl benzoyl ester, 311, 314 
bromide, 314 

tertiary, 317 
butyrate, 311 
carbamate, 312 

benzylidene derivative of, 312 
d-Menthyl carbamide, 372 
/-Menthyl carbamide, 369 
Menthyl carbonate, 312 
chloride, 313 
dixanthate, 127, 313 
ethyl ether, 311 

/-Menthyl ethyl nitrosamine, 369 
Menthyl iodide, 314, 315 
inactive, 315 
tertiary, 317 

/-Menthyl isobutyl nitrosamine, 369 
Menthyl methyl ether, tertiary, 317 
/-Menthyl methyl nitrosamine, 369 
Menthyl methyl xanthate, 312 

phenyl carbamate, 312 
d-Menthyl phenyl carbamide, 372 
/-Menthyl phenyl carbamide, 369 
d-Menthyl phenyl thiocarbamide, 372 
/-Menthyl phenyl thiocarbamide, 369 
Menthyl phenyl thiocarbamide, tertiary, 

374 

phenylurethane, 312 
phthaloxyl ester, 312 
phthalyl ester, 312 
/-Menthyl propyl nitrosamine, 369 
stearate, 310 
succinoxyl ester, 311 
succinyl ester, 311 

d-Menthyl trimethyl ammonium hydrox- 
ide, 372 

/-Menthyl trimethyl ammonium hydrox- 
ide, 370 
d-Menthyl trimethyl ammonium iodide, 

372 
/-Menthyl trimethyl ammonium iodide, 

369 
/-Menthyl trimethyl ammonium triiodide, 

370 

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-Methyl isopropyl cy- 

clohexene, 130 
oxyhexahydrotoluene, 245 
oxy-para-toluic acid, 215 
terebentene, 431 

Methoethene-5-hexene-2-acid-6, 333 
Methoethylheptanonolide, 52, 263, 266, 

323 

3-Metho-ethyl-2-hexene-dioic acid, 230 
Methoethylol-5-hexene-2-acid-6 = -Oxy- 

isopropyl-AY-hexenoic acid, 332 
Methoxybromocarvacrol, 227 

29 



Methoxybromocarvacrol acetyl ester 227 

methyl ether 227 

o-Methoxybenzylidene fenchylamine, 351 
p-Methoxybenzylidene fenchylamine, 351 
Methyl adipic acid, 129 
/3-Methyl adipic acid, 243, 299, 303, 310, 

Methyl amine, 364 

2-aminoethyl-3-pentolide, 265 
bornyl carbamide, 342 
bornyl ether, 143 
chavicol, 377 
cineolic ester, 327 
cyclohexanol, 245 
l-cyclohexanol-6-methyl-acid-4, 215 
cyclohexanone, 239, 244 
oxime, 245 
semicarbazone, 245 
dihydrocarveol xanthate, 213 
dihydrocarvyl xanthate, 74 
l-dimethyl-5-cyclohexene-l-methyl- 

acid-6, 403 
Methylene bornyl ether, 144 

isobornyl ether, 148 
Methylenic acetal of borneol = Diborne- 

olic formal, 146 
of menthol = Dimentholic 

formal, 310 
Methyl^-ethyl-S-heptanon-e-olid-l, 3 1 , 48, 

49, 52, 263, 264, 266 
oxime, 264 

3-Methyl-ethyl-2-heptene-6-onoic acid, 229 
Methyl-l-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 
o-Methyl glutaric acid, 218 
Methyl-2-heptene-2-on-6, 407 
heptenol, 330, 392 

oxide, 331 
heptenone = Methyl hexylene ketone, 

330, 398, 405 

heptenoncarboxylic acid, 406 
2-Methyl heptone-3, 6-dione, 230 

oxime, 231 

Methyl heptylene carbinol, 177, 232 
ketone, 231 

benzylidene derivative of, 231 
oxime, 232 
semicarbazone, 231 
3-Methyl hexan-3-onoic acid, 231 
Methyl hexenone, 244 

hexylene carbinol, 177, 330, 392, 406 
ketone, 329, 330, 405 

derivatives of, 330 
oxide, 331 
isobornyl ether, 148 
cis-1, 3-Methyl isopropyl cyclohexanol-5, 

315 

hexanone-5, 308 
hexane, 130 
hexene, 131 
3-Methyl isopropyl-A 2 -cyclohexenone car- 

boxylic acid, i>.">3 
Methyl isopropyl hexahydrofluorene, 307 



450 



INDEX. 



3-Methyl - 6 - isopropyl-A 2 -keto-K-hexene, 

316 

2-Methyl isopropyl pyrroline, 231 
Methyl isopropyl trioxyhexahydroben- 

zene = Trioxyterpane, 262 
ketone of homoterpenylic acid, 221, 

267 

/3-Methyl ketopentamethylene, 243 
Methyl menthylxanthate, 312 

mercaptan, 313 

2-Methyl-3-menthene heptane-6-one, 232 
2-Methyl - 3 - methyl-ol-heptan-6-one-3-ol, 

233 
1 - Methyl-4-propenyl - dihydroresorcinol, 

193 

Methyl pulegenate, 245 
pulegonamine, 363 

Flatinochloride, 364 
pyrrolidine, 31 
Methyl terpine, 318 
acetate, 318 
Monobasic acid, CgHieO, 331 

methyl ester, 331 
Monobromocamphene, 62 
camphenone, 153 
dipentene 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 

N 

Naphthenes, 132 
Neobornylamine, 344 

acetyl derivative of, 345 

benzoyl derivative of, 345 

derivatives, table of, 345 

formyl derivative of, 345 

hydrochloride, 344, 345 

platinochloride, 345 

picrate, 345 
Neobornyl carbamide, 345 

phenylcarbamide, 345 
Nerolol = Linalool, 381 
Ngai camphor, 142 
Ngai fn, 150 
Nitrocamphane, 123 
Nitrocamphene, 66 
Nitrofenchone, 158 
Nitromenthone, 241, S05 
Nitrophellandrene, 111, 374 
Nitroxylene, meta-, 330 
Nitrosobenzyl fenchylamine, 350 
Nitrosocarvenone, 217 
Nitrosodihydroeucarvone, 223 
Nitrosodipentene = Inactive carvoxime, 
96, 190 

a-nitrolanilide, 97 

0-nitrolanilide, 97 
Nitrosolimonene nitrolanilides, 79 
Nitrosomenthene, 129, 251 
Nitrosomenthenone, 251 
Nitrosomenthone, 241 



Nitrosomethyl fenchylamine, 350 
Nitrosopinene, 43, 154, 202, 336 

dibromide, 155 
Nitrosopulegone, 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 acid, 47, 56 
aldehyde, 56 

semicarbazone, 56 
silver salt of, 56 



Ocimene, 379 

Oil of absinth = Oil of wormwood, 87, 
108, 225, 415 

andropogon, 108 

schoenanthus, 389 

angelica, 108 

angostura bark, 415, 428 

anise, star, 35, 108 

artemisia (Artemisia barrelieri), 225 

asafetida, 415 

balm, 397 

basil, sweet = Oil of basilicum, 34, 
35, 324, 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, 315 
serratifolia, 315 

cade, 414, 415 

cajuput, 35, 258, 323, 432 

camphor, 35, 57, 87, 108, 257, 324, 414 

Canadian pine, 142 

cananga, Java, 381 

Canella alba, 35, 324, 417 

caparrapi, 428 

caraway, 71, 178, 185, 219 

cardamom, 87, 112, 257, 266, 324 

Carlina acaulis, 430 

cedar wood, 423 

cedro, 397 

celery seed, 71 

champaca wood, 426 

cheken-leaves, 35, 323 

chenopodium = Oil of wormseed, 
American, 87, 432 

cinnamon, 108, 324 

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 alba, 34, 72 

copaiba balsam, 417 



INDEX. 



451 



Oil of coriander, 35, 383 

coto bark, para = Oil of paracoto 

bark, 414 
cubeb, 87, 414, 424 
curcuma, 108 
dill, 71, 108, 178 
elderberry, 35, 415 
elemi, 108 
erigeron, 71, 257 

canadensis, 258 
eucalyptus, 323, 324 

amygdalina, 108 

backnousia citriodora, 397 

camphora, 286 

eloeophora, 286 

globulus, 34, 170, 266, 324 

goniocalyx, 286 

macarthuri, 388 

inacrorrhyucha, 386 

maculata, 409 

var. citriodora, 388, 409 

piperita, 285, 286 

smithii, 286 

stricta, 286 

staigeriana, 397 
European pennyroyal (Mentha pule- 

giuin), 237 

fennel, 35, 87, 155, 156 
feverfew, 133 

fleabane = Oil of erigeron, 71, 257 
frankincense = Oil of olibanum, 34, 

87, 108, 414; 
galangel, 323 
galbanum, 35, 414 

geranium, African = Oil of pelargo- 
nium, 388, 394, 395 

Bourbon, 307 

Indian = Oil of palmarosa, 388, 
394, 395 

rose = Oil of pelargonium, 388, 
394. 395 

Turkish = Oil of palmarosa, 388, 

394, 395 

ginger, 57, 108, 429 
golden rod, 87, 108, 142, 415 
guaiac wood, 426 
hemlock needle, 34, 57, 142 
hops, 380, 421 
iva, 324 

juniper berries, 34, 415 
kesso = Oil of valerian root, Jap- 
anese, 35, 57, 257 
kesso-root, 35, 87 
kuromoji, 71, 87, 178, 257 
Labrador tea, 425 
laurel berries, 34, 323 

leaves, 34, 323 

lavender, 35, 324, 381, 382, 387, 388 
lavender, spike = Oil of spike, 35, 57, 

142, 324, 381, 388 
ledum palustre = Oil of Labrador 

tea, 425 
lemon, 34, 57, 71, 108, 381, 396, 409 

grass, 388, 397, 405 
Levant wormseed, 323, 324 
limes = Oil of limetta leaf, 87, 381, 

382 397 

limetta leaf, 87, 381, 382, 397 
linaloe, 381, 382, 388 



Oiloflovage, 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 = Oil of European pen- 
nyroyal, 237 

myrcia = Oil of bay, 35, 108, 377, 397 
myrtle, 35, 87, 324 
neroli = Oil of orange flowers, 381, 

388 

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, 35 
patchouly, 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 montana, 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 
rosemary, 35, 57, 142 323 
sage, salvia oflicinalis, 34, 142, 224, 

323, 381 

sclarea, 142, 224, 323, 381 
salviol = Oil of sage, 224, 323 
sandalwood, East Indian, 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 
star anise = Oil of anise, star, 35, 

108 

sweet marjoram, 112, 257, 267 
tansy, 35, 224, 225 
thuja, 35, 155, 156, 224, 236, 237 
thyme, 35, 87, 142, 381 
turpentine, American, 34, 57, 320,431, 

432 

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 

terpeue in the oil of hops, 330 
origanum, 380 

terpenes, 28, 377 
Olibanum, 35 
Olibene. 34 
Ortho-diketone, CioHi 6 02, 309 

isopulegol, 247 

isopulegone, 246 

terpenes, 84, 120 

Oxalic acid, 158, 212, 222, 224, 277, 392 
Oxide, C 9 Hi6O2, 233 

C9HieO2, bromide of, 233 
Oxy-acid, CsHuOs, 274 
Oxy-acid, CioHieOs, 403 

o-amyrin, 433 

o-amyrin acetate, 433 
o-Oxy-benzylidene fenchylamine, 351 
p-Oxy-benzylidene fenchylamine, 351 
o-Oxy-benzylidene d-menthylamine, 372 

Z-menthylarnine, 369 

pinylamine, 338 
1-8-Oxybromotetrahydrocarvone, 209, 221, 

267, 291 

Oxycamphene = Carvenone, 62 
Oxy-camphenilanic 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 

Os ydihydrofencholenonitrile, 167 
a-Oxydimethyltricarballylic acid, 55 

lactone, 55 
D-d-Oxyfenchenic acid, 70 

acetyl derivative of, 70 
D-J-Oxyfenchenic acid, 69 
ZM-Oxyfenchenic acid, acetyl derivative 

of, 69 

Z-d-Oxyfenchenic acid, 70 
Oxyfenchenic acid, racemic, 70 
Oxygenated compound, CioHieO, 337 
Oxy-2-hexahydro-p-cymene, 237 
homopinic acid, 55 
hydromenthonylamine, 303, 393, 413 
isocamphoronic acid, 52 
o-Oxy-isocamphoronic acid lactone, 55 
a-Oxy-isopropyl-AT-hexenoic acid, 332 
Oxy-ketone, 274 

semicarbazone, 274 
menthylic acid, 129, 299, 810 
derivatives of, 310 
oxime, 804, 310 
methylene camphor, 140 
methylene carvone, 194 
methylene menthone, 305 

derivatives of, 305 
Oxymethylene tetrahydrocarvone, 221, 

290 

thujone, 229 
a-Oxy-a 1 -methyl-a-isopropyl-adipic acid^ 

218 

Oxy-oxime, CioHi3(OH)NOH, 181 
8-Oxy-o-oxyisopropyl hexenoic acid, 332 
Oxypinic acid, 56 
Oxyterpenylic acid, 84, 196 

dilactone, 84, 196 
Oxytetrahydrocarvone, 214, 220 
semicarbazone, 214 
cymenes, 20, 21 
Oxytrimethylsuccinic acid, 52 



Palmityl-j3-amyrin, 434 
Paracajeputene, 432 
Parapulegone, 246 
Paratoluic acid, 215, 274 
Paraxylic acid, 158 
Patchoulene, 425 
Patchouly alcohol, 425 

camphor, 425 
y-Pentylene glycol, 331 

oxide, 331 



INDEX. 



453 



Peppermint camphor, 308 
Pernitrosocamphenone, 153 

dibromide = Dibromopernitroso- 

camphor, 153 

Pernitrosocamphor, 153, 251 
fenchone, 166 
inenthone, 304 
thujone, 228 
Phellandrene, 108, 377 
diamine, 110, 375 
dibromide, 109 
nitrosite, 109, 364, 375 
Phenyl bornylcarbamide, 342 

dihydrocarvylurethane, 213 
Phenylurethane, CnlfeOsN, 129 
Picean-ring, 56 
Pimelic acid, 230 
/3-Pimelic acid, 310 
Pinacone, C2oHs4O2, 170 
Pinacpline, 329 
Pinarin, 56 
Pinene, 34 

action of hypochlorous acid on, 40 

of nitrous acid on 2 41, 202 
formaldehyde derivative of, 41 
acetate, 41 
benzoate, 41 
dihydrobromide, 41 
dihydrochloride, 41 
behavior towards bromine, 44 
dibromide, liquid, 45 

solid, 45 
dichloride, 46 
glycol, 46, 152 
hydriodide, 40 
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 
phthalamic acid, 339 
picrate, 38 
Pinenol, 202 
acetate, 202 
dibromide, 202 
Pinenone, 203 

dibromide, 203 
semicarbazone, 203 
Pinenonoxime, 203 

benzoyl derivative of, 203 
butyryl derivative of, 203 
dibromide, 203 
phenylcarbimide, 203 
Pine wood, 35, 87,99 
Pinic acid, 53, 56 
Pinocampholenamide, 155 
Pinocampholenic acids, 50, 155 
Pinocampholenonitrile, 154 
Pinocampheol, 155 
Pinocamphone, 154 
oxime, 154 
semicarbazone, 155 



Pinocamphonitrile, 154 
Pinocamphylamine, 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 
i-Pinodihydrocampholenolactone, 50 
Pinole, 42, 47, 260, 274 
bisnitrosochloride, 283 

beuzoyl derivative of, 284 
ethoxyl derivative of, 284 
methoxyl derivative of, 284 
cis-Pinole dibromide, 278 
Pinole glycols, 334 
cis-Pinole glycol, 279 
cis-trans-Pmple glycol, 279 
d-cis-trans-Pinole glycol, 280, 282 
cis-Pinole glycol, 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 
nitrolainine, 284 

hydrochloride, 284 
amines, 284 
anilide, 285 
benzylamine, 285 
/3-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 

amiue from, 253 

carbamide of, 253 
semicarbazone, 253 
Pinonic acids, 48, 49, 53 

derivatives of, 48, 49 
keto-lactories from, 48, 49 
oximes of, 48, 49, 53 
phenylhydrazones of, 53 
semicarbazones of, 48, 49 
Pinononic acid, 47 
oxime, 47 
Pinoylformic acid, 54 

derivative of, 54 
phenylhydrazone, 54 
Pinylamme, 154, 202, 336 
acetyl derivative of, 337 
benzoyl derivative of, 338 



454 



IXDEX. 



Pinylamine, benzylidene derivative of, 338 
furfur o-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 
Pinylcarbamide, 338 
Polyterpenes, 17, 414, 431, 432 
Propionyl feuchylamine, 349 
d- Propionyl menthylamine, 371 
/-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, 363 

benzoyl 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, CioHiaNCh, hydrated 
(Beckmann and Pleissner's oxime) 
= Pulegone hydroxylamine, 240 
hydrated, acetyl derivative of, 241 
benzoyl derivative of, 241 
hydrochloride, 241 
CioHieNOH, normal, 240 

hydrobromide, 239 
Pulegylaniine, 240, 362 
hydrochloride, 363 
oxalate, 362 



Pulegyl carbamine, 363 

phenylcarbamide, 363 
Pyruvic acid, 237 

Q 

Quinone from thujone tribromide, 227 



Racemic-a-carvylamine, 356 

/3-carvylamine, 356 
Reduction products of carvone, 194 
RSuniol, 389, 394, 395 
Rhodinal =Geranial. 388 
Rhodinol = Geraniol, 388, 389, 394 
Rhodinolic acid = Geranic acid, 406 
Roseol, 388, 389, 394 

S 

Sabinene, 121 

dibromide, 121 

glycol, 121 

ketone, 122 

semicarbazone, 122 
Sabinenic acid, 122 
Sabinol, 204 

acetate, 204, 205 

addition-products of, 205 
Sabinyl glycerol, 205 
Sal viol = Thujone, 225 
Santalal, 427 

semicarbazone, 427 
a-Santalene, 427 

acetate, 427 

dihydrochlpride, 427 

nitrolpiperidide, 427 

nitrosocnloride, 427 
/3-Santalene, 427 

acetate, 427 

dihydrochloride, 427 

nitrolpiperidides, 427 

nitrosochlorides, 427 
Santalic acid, 427 
a-Santalol, 426, 428 

acetate, 426 
/3-Santalol, 426, 428 

acetate, 426 
Sesquiterpene alcohol, 427 

alcohols, 414 
Sesquiterpenes, 17, 4H 

classification of, 430 
Silver cineolate, 327 

a-fencholenate. 164 
Sobrerol = Pinole hydrate, 276 
Sobrerone = Pinole, 276 
cis-Sobrerytrite (menthane-1, 2, 6, 8-tetrol) 

= cis-Sobrerythritpl, 40, 282 
cis-trans-Sobrerythrite (menthane-1,2,6,8- 
tetrol) = cis - trans - Sobrerythritol, 
277 

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 
Synthetical isoborneol = Fenchylalcohol, 

171 

pulegol, 247 

pulegone = Ortho-iso(?)-pulegone, 246 
benzylidene derivative of, 247 
compound, CisHsoO, from, 247 
derivatives, table of, 250 
semicarbazone, 247 
terpene, 120, 247 



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 /3-amyrin and 
derivatives, 434 

Properties of bornyl esters, 143 

Properties of linalool from different 
oils, 382 

Pulegone, isopulegone, synthetical 
or ortho-isopulegone and deriva- 
tives, 250 

Eelation of terpineol (m. p. 35) to 
other terpene derivatives, 268 

Rotatory powers of the limonene de- 
rivatives, 86 

Specific and molecular rotatory 
p_owers of fenchylamine and deriva- 
tives, 351 

Specific and molecular rotatory pow- 
ers of d- and Z-menthylamines and 
derivaties, 373 

Specific rotatory powers of carvone 
and its derivatives, 197 

Transformations in the terpene series, 
122 

Transformations of the keto- and oxy- 

hydrocymenes, 335 
Tanacetene = Thujene, 118, 360 



o-Tanacetogendicarboxylic acid, 205, 229, 

230 

anhydride, 230 

0-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 
Terpadienes, 23 
Terpane = Cineole, 324 

= Hexahydrocymene, 23, 130 
Terpanes, 130 
Terpan-2-ol = Carvomenthol, 291 

3-ol = Menthol, 308 
Terpanols, 23 
Terpan-2-one = Carvomenthone, 287 

-3-one = Menthone, 295 
Terpanones, 23 

Terpan-1, 4, 8-triol = Trioxyterpane, 334 
A 1 -Terpene = Carvomenthene, 124 
A 3 -Terpene = Menthene, 126 
Terpene from the resin of Indian hemp, 

119 

hydrochloride of, 119 
Terpenes proper, 17, 34 

transformations of, 122 
A 1 -Terpen-8-ol, 189, 256 
A 1 -Terpen-4-ol, 256, 261 
A8< 9 >-Terpen-l-ol, 256, 273 

derivatives of, 274 
A*(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-Terpine, 320 
trans-Terpine, 319 
Terpine acetate, 322 

hydrate, 254, 320, 432 
oxidation of, 322, 323 

mono-acetyl ester, 322 
methyl-, 318 

acetate of, 318 

oxidation of, 319 
Terpinene, 112, 213, 357 

benzoyl isonitrosite, 116 

dibromide, 114 

nitrolamine, 117 



INDEX. 



Terpinene nitrolamine, dibenzoyl deriva- 
tive of, 117 
nitrolamines, 116 
amylamine, 118 
benzylainine, 118 
diethylamine, 118 
dimethylamine, 117 
ethylamine, 118 

nitroso-derivative of, 118 
methylamine, 117 
piperidide, 118 
nitrosite, 114 
oxide oxirqe, 115 

isomeride of, 115 
Terpineol, 254 

isomeric, m.p. 32 to 33, 273 

nitrolpiperidide, 274 

nitrosochloride, 274 

phenylurethane, 274 

isomeric, m.p. 69 to 70 = A^W.Ter- 

pen-l-ol, 269 
" Terpineol," liquid, 254, 257, 258 

dibromide, 257 
Terpineols, 254 266, 267 
Terpineol, solid, m.p. 35, 255, 258 
dibromide, 198, 260 
keto-lactpne from, 263 
nitrolamines, 262 
anilide, 262 
piperidide, 262, 266 
nitrosate, 262 
nitrosochloride, 261, 266 
oxidation of, 262 
relation to other terpene 

derivatives, table of, 268 
Terpines, 319 
Terpinolene, 105 
dibromide, 107 
tetrabromide, 107 
Terpinyl acetate, 259 
formate, 258, 259, 266 
methyl ether, 259 
phenylurethane, 259, 266 
Tertiary carvoinenthol, 316 
carvomenthylamine, 373 

derivatives of, 374 
carvomenthyl bromide, S17, 373 
carvomenthyl iodide, 816. 373 
menthol, 317 
menthylamine, 374 

derivatives of, 374 
menthyl acetate, 317 
bromide, 317, 374 
iodide, 317,