5 o SCIENCE PROGRESS 



pinene a formula with a. para linkage, still containing the propyl 

 group. But by 1894 he was led to a different expression as a 

 consequence of studying the oxidation of pinole, C 10 H 16 O, which 

 is obtained by treating with dilute acids the compound called 

 sobrerol in honour of its discoverer Sobrero. 1 This is a glycol 

 formed by exposing pinene to contact with oxygen and water in 

 the presence of sunlight, also by oxidation of pinene by means 

 of mercuric acetate, and among the products of the action of 

 nitrosylchloride on pinene. For pinole Wagner proposed the 

 following constitutional formula : 



CH 2 — CH— CH a 



I 



CMe 2 



\ 



CH = CMe— CH 



By careful oxidation of pinole with permanganate Wagner 

 obtained first a quantitative yield of the glycol C 10 H 10 O(OH) 2 

 which in accordance with his rule indicated the presence of one 

 ethylenic bond in the molecule. Terpenylic acid was found to 

 be the final chief product. 2 



Terpenylic acid, discovered by Hempel in 1875, had already 

 been shown by Schryver 3 to be a lactone of the following 

 structure : 



CH. CH CH 



2 



OC— O— CMe, CO..H 



It may be assumed that the pinole from which terpenylic 

 acid is produced already contains the grouping 



CH 2 CH CH2 



I I I 



C — O — CMe 2 C 



and the question only remains how this is associated with the 



residue CMe and the two hydrogen atoms which have been 



removed. 



1 Compt. Rend. [1 851}, 33, 66. 



3 Ber. [1894], 24, 1644. 



8 Trans. Che?n. Soc. [1893], 1327. 



