— 184 — 



which he gave the name of dihydrocamphoceenic acid amide 1 ). Bouveault - 

 and Blanc 2 ) have demonstrated that this compound is derived from 1,3-iso- 

 propylpentane carboxylic acid. By treating it with bromine and potash liquor 

 this amide was converted by Wallach into the corresponding base, which 

 contains one carbon atom less. This base was converted into the alcohol 

 by treating it with nitrous acid, and the alcohol was oxidised with chromic 

 acid, the result being the ketone l,3-isopropylc?/dopentanone. (m. p. of the 

 semicarbazone 192 to 193°.) Dihydropinolone was prepared synthetically 

 from 1,3-isopropylc^/dopentanone by treating it with bromopropionic ester. 

 The acid which is generated as the product of the reaction, when sub- 

 mitted to dry distillation, yielded a hydrocarbon, the nitrosochloride of 

 which gave rise to a ketone which was reduced to dihydropinolone by 

 Paal's method. This hydrocarbon, of which the formula probably corresponds 

 in the main with that set forth below, was also prepared synthetically from 

 dihydropinolone. Reduction of this ketone yielded dihydropinolol (b. p. 215 

 to 216°; d 19 o 0,8920; n D18 o 1,4569) which, when warmed with chloride of 

 zinc, gave rise to the hydrocarbon which was the object of the experiment 

 (b. p. 171 to 174°; d 22 o 0,812; n D22 o 1,4515). 



CH 3 



I 

 C 



HC/\CH — O 



H 2 cl J CM* 



CH 



I 

 C 



H 3 C CH 3 



Pinol. 



CO 



H 2 (T ]CH 2 



H 2 C CH-CH(CH 3 ) 2 



1, 3-Jsopropylq/cZopentanone. 



CHCOCH 3 



H 2 C 



H 2 C 



CH 2 

 CH-CH(CH 3 ) 2 



Dihydropinolone. 



CH 3 



CH 

 C 



H 2 C / ^CH* 



H 2 C CHCH-(CH 3 ) 2 



Hydrocarbon from 

 1, 3-Isopropylci/cZopentanone. 



According to a communication by W. Bonsdorff 3 ) the calcium salt of 

 pinic acid, when subjected to dry distillation, does not yield the bicyclic 

 ketone which would be expected, but most probably l-^sopropylene-2-keto- 

 pentamethylene. Bonsdorff obtained three fractions, which boiled at 4 mm. 

 between 34 to 50°, 50 to 100° and 100 to 102°. These fractions do not react 

 with semicarbazide-, thio-semicarbazide- or hydroxylamine hydrochlorides, 

 but fraction II, when treated with free semicarbazide yielded a semicarbazonf , 

 m. p. 159 to 161°, from which the ketone was regenerated. This ketone 

 boiled between 69 and 71° (8 mm.), its other constants being as follow: 



x ) Comp. Report October 1906, 138. 



2 ) Comp. Report April 1908, 191. 



3 ) Berl. Berichte 44 (1911), 3208. 



