Scientific and/other notes on essential oils. 21 



the combined action of sodium and amyl alcohol. Nor do sodium and ethyl alcohol 

 reduce isoamyl-«-dehydrophellandrene, whereas the use of amyl alcohol effects at least 

 a partial reduction. The chemical proof of the presence of the 3 double bonds in the 

 synthetic sesquiterpene was supplied by the hydrogenation by means of hydrogen in 

 the presence of platinum black. This led to the formation of a hydrocarbon, Ci 5 Ho , 

 tetrahydroisoamyl-a-phellandrene, whose boiling point lay between 131 and 133° (14 mm.) 

 and which gave the following constants: d 22o 0.8250; « D — 1°30'; n D20O 1.45562. Its 

 properties are quite in accord with those of hexahydrobisabolene, hexahydrozingiberene, 

 and of hexahydroq/doisoprenemyrcene *). The action of hydrochloric acid on the 

 synthetic sesquiterpene does not lead to the formation of a solid addition-product. 



Besides the above-mentioned sesquiterpene, Roenisch obtained a small quantity of 

 a higher-boiling fraction which apparently contained the alcohol Ci 5 H 26 belonging to 

 the sesquiterpene. This fraction was further investigated by Semmler and Oelsner 2 ). 

 Whereas Roenisch had made his investigations in an absolute benzene solution with 

 the addition of only a small quantity of absolute ether, Semmler and Oelsner succeeded 

 in obtaining a better yield of products containing oxygen by working in an absolute 

 ethereal solution. Strange to say they obtained by this means chiefly a sesquiterpene 

 ketone, Ci 5 H 2 6 0. Under these conditions Grignard's reaction had taken an abnormal 

 course by the addition of the amyl radicle to the double bond, instead of to the 

 oxygenated carbon atom. This ketone, isoamyldihydrocarvone, had a boiling point 

 between 144 and 149° (10 mm.) and the following constants: d 20O 0.9022; « D — 8°; 

 n D20 o 1.47694. Reducing agents, such as sodium and alcohol, produced a monocyclic 

 alcohol, Ci 5 H 28 (boiling point 150 to 155° [10 mm.]; d 20 o 0.8993; « D — 1©. n D20O 1 .47449). 

 The hydrogenation of this alcohol with only one double bond with the help of platinum 

 and hydrogen produced the saturated monocyclic alcohol C15H30O; boiling point 145 

 to 152° (12 mm.); d 20 o 0.8906; « D — 1°; n D20O 1.46855. 



Besides the monocyclic ketone, Semmler and Oelsner obtained a bad yield of a 

 tertiary alcohol, Ci 5 H 26 0, isoamyldihydrocarveol; boiling point 155 to 170° (12 mm.); 

 d 20O 0.9217; « D — 4°; n D20 o 1.4917. A natural monocyclic sesquiterpene alcohol, Ci 5 H 26 0, 

 elemol, had already been isolated from elemi oil by Semmler and Liao 3 ). 



By means of the synthetic experiments mentioned above, Roenisch had proved 

 that monocyclic sesquiterpene products containing oxygen were not to be found in 

 ammoniacum oil, as they all showed a much higher specific gravity than the fractions 

 of this oil. As the possibility still remained that products of the aliphatic series 

 were present in the oil, he hydrogenized with the help of hydrogen and platinum the 

 aliphatic sesquiterpene alcohol, farnesol, in order to obtain comparative data, and 

 obtained hexahydrofarnesol ; boiling point 145 to 155° (15 mm.); d 220 0.8387; « D + 0; 

 n D22 o 1.44525. However, he did not succeed in producing the simply and doubly 

 unsaturated alcohol whose properties might have served for the identification of the 

 compounds found in gum ammoniac oil. 



It is highly probable that in the lower-boiling fractions of the gum ammoniac oil 

 a terpene was present which, however, it was quite impossible to identify. The saponified 

 fractions, boiling between 68 and 120° (11 mm.), contained (Minalool. It was purified 

 over the sodium compound and characterized by its phenylurethane (melting point 

 65°). Apparently, the linalool is present as acetate. Citronellyl acetate also is, as it 

 seems, present in the lowest-boiling fractions. Oxidation by means of bichromate of 



!) Comp. Report October 1913, 34, 136; April 1915, 85. — 2 ) Unpublished paper. — 3 ) Berl. Berkhte 

 49 (1916), 796; Report October 1916, 20. 



