Notes on scientific research. 139 



The diketone Ci8H 2 oG 2 from natural selinene referred to above has been further 

 oxidised with alkaline bromine solution by Semmler and Risse 1 ), who obtained from 

 it a tricarboxylic acid Ci 2 Hi 8 G , m. p. 188°, of which the methylester CisH^O* boils 

 between 200 and 205° (8 mm.). The acid being tribasic, it follows that the diketone 

 must contain in the first place a COCH ;r and secondly a CO-group in a ring which 

 undergoes disruption during oxidation, by which both the keto-group and the ChL- 

 group adjacent to the keto-group are oxidised into carboxylic groups. 



Diketomonocarboxylic acid Ci 4 H 22 4 from the regenerated selinene (see above), 

 when oxidised with alkaline bromine-solution yields the same ketomonocarboxylic acid, 

 m.p. 188°. 



Cymene. P. Sabatier and E. Senderens 2 ) have obtained o-, m-, and p-menthane 

 from o-, m-, and j9-cymene by passing the vapours, mixed with hydrogen, over heated 

 nickel. m-Menthane has also been prepared by the reduction of d-sylvestrene, and 

 this preparation showed a greater density (dfo 0,81 16; [«] D + 1,60°) than did the inactive 

 product from m-cymene (d^ 0,7965). 



Alcohols. 



Menthol. H. Rupe 3 ), in a paper on the effect of the constitution upon the 

 rotation of optically active bodies, describes the menthylesters of numerous derivatives 

 of acetylacetic and benzoylacetic acids, as well as of «-benzylcinnamic and dibenzyl- 

 acetic acids. 



By warming menthol with phenylacetic acid in the presence of sulphuric acid 

 J. B. Senderens and J. Aboulenc 4 ) have obtained menthyl-phenylacetate, a colourless 

 liquid, b. p. 205,5° (25 mm.), di 7 o 0,9887. The menthylester of phenylpropionic acid 

 melts at 28,5° and boils at 216° (25 mm.). 



Q/cfohexanol, when heated with benzoic acid or its homologues and sulphuric acid, 

 does not afford the expected ester, but yields c?/c7ohexene instead. But with phenyl- 

 acetic or phenylpropionic acids, in which the acid group is not linked directly to the 

 nucleus, esterification takes place readily. 



Borneol. When preparing camphene from borneol and dilute sulphuric acid, 

 P. Golubeff 5 ) obtained as a by-product bornyl ether, (C 10 H 17 ) 2 O, b.p. 312 to 314° (d^0,960; 

 [«] D — 88,56°; n D24 o 1,494), which, when oxidised with nitric acid, affords camphor. 

 Heated under pressure with hydrochloric acid, it yields camphene hydrochloride. The 

 principal product formed in the reaction was a camphene which showed a great 

 resemblance to the camphene of Siberian pine-needle oil, but which was inactive: 

 m.p. 48 to 49°, b.p. 157 to 160°. 



On a terpene alcohol from pinene hydriodide, see p. 136. 



Aldehydes. 



L. Wolff 6 ) has worked out a method for substituting hydrogen for the oxygen-atom 

 of the ketones and aldehydes. With this object in view he heats the semicarbazones 



*) Berl. Berichte 46 (1913), 599. — 2 ) Compt. rend. 156 (1913), 184. — 3 ) Liebigs Amiahn S9b (\9\3), 87. 

 4 ) Compt. rend. 155 (1912), 1254. — 5 ) Journ. russ. phys. cfiem. Ges. 44 (1912), 1061 ; Oicm. ZentraM. 1913, I. 24. 

 6 ) Liebigs Annalen 394 (1912), 86. 



