— 181 — 



oil a solid dihydrochloride, m. p. 69 to 70°, from which, by splitting off 

 hydrochloric acid by means of sodium acetate and glacial acetic acid, 

 they obtained an active hydrocarbon which differed in its properties from 

 the original caryophyllene. Other subsequent investigators of caryo- 

 phyllene have never again prepared caryophyllene dihydrochloride, from 

 which it might be inferred that the body was difficult to obtain. But 

 this is by no means the case. The dihydrochloride can be obtained with 

 at least as much ease as can other hydrochlorides, and is especially dis- 

 tinguished by its exceptional powers of crystallisation; a property which 

 renders it particularly suitable for the detection of caryophyllene in 

 essential oils. 



The caryophyllene which we employed in our experiments was deriv- 

 ed from oil of clove-stems, and possessed the following constants: 

 b. p. 259 to 261°, d 15 o 0,9064, a D — 7° 45', [a] D — 8,55°, n D20O 1,50003. We 

 prepared the hydrochloride by passing hydrochloric acid into a well- 

 cooled ethereal solution of the hydrocarbon. After being saturated, the 

 product of reaction was left standing for a day, after which the ether 

 was evaporated. The residue, when stirred with alcohol in a freezing 

 mixture, solidified immediately. The dihydrochloride, which was obtained 

 in the form of fine needles by recrystallisation from methyl alcohol, had 

 a m. p. of 68 to 70°, agreeing in this respect with the data of Schreiner 

 and Kremers. It was optically active, the lasvorotatory caryophyllene 

 yielding a dextrorotatory hydrochloride, |>] D + 49,34° in a 13,68°/o ethereal 

 solution. 



The hydrocarbon which was obtained by splitting off hydrochloric 

 acid by means of sodium ethylate possessed the following properties: 

 b. p. 257 to 259° (738 mm.), d 15 o 0,9191, d 20 o 0,9157, « D — 35°37', n D20O 1,49586, 

 mol. refr. found 65,04, calculated for Ci 5 H 2 4 /f 64,45. 



According to the molecular refraction the body is a tricyclical, simple 

 unsaturated hydrocarbon, hence it follows that during the splitting-off of 

 hydrochloric acid (which takes place with change of rotation) one mole- 

 cule of hydrochloric acid is eliminated with the formation of a ring. The 

 hydrocarbon absorbs two atoms of bromine. The action of hydrochloric 

 acid does not result in the reconstitution of caryophyllene dihydrochloride, 

 nor in the formation of a nitrosite or nitrosate. Schreiner and Kremers 

 also have observed the last-mentioned facts. Neither is the hydrocarbon 

 identical with clovene, the inactive tricyclical sesquiterpene which results 

 from caryophyllene alcohol by elimination of water. 



In order to facilitate comparison we set forth below the constants of 

 the hydrocarbons in tabular form. 



The liquid hydrochlorides which were formed under the influence of 

 hydrochloric acid have not been further investigated. An effort was made, 

 indeed, to purify them by distillation in vacuo (5 to 6 mm.), but this was 

 abortive, as they decomposed, eliminating hydrochloric acid. It may 



