258 



REPORTS ON THE STATE OF SCIENCE. 



was a comparison of its properties with those of dihydrolaurolene and 

 dihydroisolaurolene, with which hydrocarbons it has been supposed by 

 Zelinsky and Lepeschkin ^ to be identical. This comparison has now been 

 completed,^ with results which prove conclusively that neither dihydro- 

 laurolene nor dihydroisolaurolene is identical with 1 : 1-dimethylhexahydro- 

 benzene, as will be seen from the following tabulated summary of their 

 properties ; — 



There is little to be said regarding the constitution of dihydrolaurolene 

 on the present occasion, but it seems most probable that this substance is 

 a mixture of hydrocarbons ; whereas dihydroisolaurolene is proved by the 

 following considerations to be a pentamethylene derivative. 



In 1898 Blanc ^ definitely established the constitution of isolaurolene 

 in the following manner. Accepting his formula for isolauronolic acid (1) 

 as correct, he believed isolaurolene to be represented by formula 2. 



CHj-C(CH,)j CH„ 



I 

 (1) C.CH, =COj + 



CH,-C.C0OH 



-C(CH,), 



I 



C.CH, (2) 



CHj-CH 



That is to say, that during the loss of carbon dioxide no change in the 

 structure of the ring takes place. This was proved by the fact that 

 isolauronolic chloride (3), when treated with zinc methide, gave rise to 

 the same ketone (4) as is produced by the action of acetyl chloride on 

 isolaurolene in presence of aluminium chloride : 



CH2-C(CH,), 



(3) 



C.CH, +Zn(CH3)j\ 



CHj-C 



COCl 



CHj-C(CH3)j 



C.CH. + CHj.COCl-* 



CH,-C(CH3), 



I 

 C.CH, 



II 

 CH,-0 . CO . CH, 



(4) 



CHj-CH 



Blanc further showed that when isolaurolene was oxidised with 

 potassium permanganate there was obtained -y-acetyldimethylbutyric acid 



' Annalen, 1901,319, 303. 



* Crossley and Renouf, J. C -S., 1906, 88, 26 



' Bull. Soc. Chim... 1898 [iu], 19, 699. 



