— 102 — 



venone, yields «-terpinene. We do not propose here to enter into the 

 question of the subsidiary reactions which also occur with menthenone, 

 and which indicate the improbability of the hydrocarbon being a uniform 

 product. Our purpose was on the one hand to find out the behaviour 

 of the ketone towards phosphorus pentachloride and, on the other, to 

 utilise the resulting compounds in order to obtain further corroboration 

 of the accuracy of our view as to the constitution of zl ^menthenone. 



Decomposition of the ketone: We succeeded in decomposing 

 the ketone by carefully oxidising it with permanganate. For this purpose 

 we mixed 150 g. ketone with 312 g. permanganate of potassium and 50 g. 

 potash, together with 10 kilos ice and 10 kilos water, in a shaking-machine. 

 No appreciable quantities of unattacked ketone passed over when the 

 mixture was subjected to distillation with steam. As no neutral product 

 of oxidation could be isolated from the concentrated liquors, we treated 

 the latter at a low temperature with dilute sulphuric acid, driving-off the 

 volatile acids with steam. These acids consisted partly of small quantities 

 of fatty acids (identified as such by the odour), and principally of formic 

 acid. We did not trouble to isolate the last-named, contenting ourselves 

 with identifying it by its- decomposing action upon salts of silver. 



The non-volatile acids were absorbed with ether (the approximate 

 quantity of acid present being ascertained by titration), and shaken up 

 several times each with a quantity of soda insufficient to produce saturation. 

 The first two soda-extracts contained the stronger acids, while the weaker 

 acids were found in the last two. 



The acids recovered from the first two extracts were directly con- 

 verted into their copper salts, the greater part of which readily dissolved 

 in water. The acid, having been eliminated from the solution of copper 

 salt by acidulation, solidified completely in the course of a few days. 

 Recrystallised from water or light petroleum it melted at 143°, the yield 

 being 45 g. 



I. 0,1836 g. subst: 0,3683 g. C0 2 , 0,1386 g. H 2 0. 

 II. 0,1690 g. subst: 0,3396 g. C0 2 , 0,1304 g. H 2 0. 



Found Calc. for Ci H 18 O 5 



I. II. 



C 54,70°/o 54,80°/o 55,04°/o 



H 8,39°/o 8,57°/o 8,25%. 



By titrating with semi-normal potash liquor we discovered the acid to 

 be dibasic. The fifth oxygen-atom is linked in the hydroxyl form. When 

 heated above its melting-point the acid readily splits off water, a lactonic 

 acid being formed. In order to ascertain the nature of this acid, which we 

 identified as an as yet unknown a-hydroxy-a-methyl-«'-isopropyladipic acid 

 (methyl-2-heptanol-6-dicarboxylic-3,6-acid), we oxidised it with chromic acid 



