Notes on scientific research. 137 



probably identical with /?-phellandrene (zJ lCn,2 -menthadiene). The authors believe that 

 intramolecular rearrangements have occurred during the formation of the zl'-menthene 

 dibromide, or during the process of the splitting-off of bromine from that dibromide. 

 Theoretically the formation of «- or /3-phellandrene is to be expected. 



Sesquiterpene (?) from a-hederagenin. From rc-hederin, a glucoside found in 

 ivy-leaves, and insoluble in water, A. W. van der Haar 1 ) has obtained, by hydrolysis 

 with dilute sulphuric acid, arabinose and a methyl-pentose as well as «-hederagenin. 

 Upon distillation in a current of hydrogen, «-hederagenin yields an oil which volatilises 

 with steam; b. p. 245 to 255°, n D130 1,5303. Determination of the molecular weight and 

 combustion showed the substance to possess the composition of a sesquiterpene Cir.hW 



Selinene. In our Report of April 1910, p. 32, we described the isolation of a 

 sesquiterpene from celery oil, to which we gave the name of selinene and from which 

 we obtained a dihydrochloride from which it was possible to recover the sesquiterpene. 

 Afterwards F. W. Semmler and F. Risse-) took up the study of selinene and discovered 

 that in the preparation of selinene dihydrochloride it is of advantage to pass into the 

 essential solution of the sesquiterpene a mixture of one part hydrochloric acid gas and 

 three parts of air, better yields being obtained by this method than from the introduction 

 of pure hydrochloric acid gas. The authors did not regenerate the selinene from the 

 dihydrochloride with sodium ethylate, as we did, but with saturated methyl alcoholic 

 potash liquor. They first allowed the hydrochloride to stand for a few hours with this 

 liquor at room-temperature, after which they gradually raised the temperature, finally 

 heating the mixture on the water-bath. By this method they obtained a sesquiterpene 

 with the following constants: b. p. 128 to 132° (11mm.), d 20 o 0,9190, « D + 61°36', 

 n D 1,50920. These values are in agreement with the constants of the sesquiterpene 

 which was obtained by us, but the rotation is higher. Hence Semmler and Risse are 

 of opinion that it is not impossible that in our case the rotation was depressed through 

 the presence of a second sesquiterpene and that, on the other hand, the mild reagent 

 used by them did not perceptibly change the hydrocarbon. When selinene dihydro- 

 chloride is reduced with sodium and alcohol it yields tetrahydroselinene. A simpler 

 method of arriving at the same hydrocarbon is to reduce selinene with platinum and 

 hydrogen. The tetrahydroselinene obtained by this method boils at 126 to 128° (10,5 mm.): 

 d 20 o 0,8881, « D -f- 7°, n D 1,48259. By treating selinene dihydrochloride with milk of lime 

 the authors obtained a bicyclic, simply unsaturated alcohol Ci 5 H 26 which they call 

 selinenol: b. p. 155 to 163° (19 mm.), d 20 o 0,9627, « D + 52°36', n D 1,50895. In addition 

 there were formed selinene and, apparently, a glycol Ci 5 H 2S 2 . When reduced with 

 platinum and hydrogen selinenol is converted into dihydroselinenol, m. p. 86 to 87°. 

 The authors recommend the preparation of dihydroselinenol for the purpose of detecting 

 the presence of selinene. 



Semmler and Risse 3 ) also describe the products obtained by them in oxidising 

 selinene with ozone. From natural selinene they obtained as a neutral oxidation- 

 product a diketone Ci 3 H 2 o0 2 , which, when separated from the disemicarbazone (m. p. 22S°), 

 boils between 178 and 180° (11mm.): d 20O 1,0566, « D + 15°, n D 1,4994. When the 

 formula of the diketone is compared with that of selinene it is clear that two carbon 

 atoms must have been split off which are attached to the residual carbon nucleus, Ci S , 

 either in a side-chain or semicyclically. Furthermore, the diketone being completely 



!) Arch, der Pharm. 250 (1912), 434. — 2 ) Berl. Berichte 45 (1912), 3301. — s ) Ibidem 3725. 



