326 REPORT— 1900. 



The change is not unlike that involved in the transformation of 

 pinacone into pinacoline : 



CMeg.OH CMe,3 



CMe, -> CMe + H,0 



I II 



OH O 



or of pinacolyl alcohol into tetramethylethylene : 



CMe3 CMe., 



+ H,0 



CHMe.OH CMe. 



2 



changes apparently characteristic of complexes which contain several 

 adjacent methyl groups. It is well known, moreover, that in the forma- 

 tion of benzenoid derivatives from hexamethylene compounds the methyl 

 groups usually appear to move to adjacent carbon atoms ; as, for example, 

 in the change of isolauronic acid into paraxylic acid 



/CMe^ 



/ \ 

 CH2 CO -> 



II 



CH., CH CH CH 



\ / \ / 



C.COOH C.COOH 



as well as in numerous similar instances investigated by Baeyer. 



It may be urged that the conditions under which isolauronolic acid is 

 produced from camphor are not such as would be expected to produce 

 deep-seated isomeric change, but such a contention is altogether insufficient 

 to seriously militate against the great probability that it does actually occur 

 ifli this instance. It is easy to cite evidence that isomeric changes of very 

 unexpected character do occur under conditions which would at first sight 

 appear to be insufficient to produce them, such as, for example, the change 

 of c(-dibromocamphor into bromocamphorenic acid when warmed with an 

 alcoholic solution of silver nitrate on the water bath, which certainly 

 involves the absorption of a carbon atom into a ring somewhat in this 

 manner : 



CH CBr 



CH., I CBra 

 CMe., 

 I +H.,0= 



CH, I CO 



I 

 C 



Me 



C.COOH 1 

 Me 



and the change of pinacone into pinacoline does not involve any violent 

 action such as is usually associated with the production of benzene 

 derivatives from cyclomethylene compounds. 



1 Lapworth, Trans. Chem.'Soe., 75, 1138. 



