- i6 5 - 



Hydrocarbons, 



a -Pin en e. It might be assumed that by eliminating water and 

 carbon dioxide gas from nopinol-acetic acid it would be just as feasible 

 to obtain a-pinene as /3-pinene. Up to the present, however, Wallach x ) 

 had only succeeded in carrying out the synthesis of /?- pinene, but 

 now, by the application of special experimental conditions, this in- 

 vestigator has also been able to obtain lsevo-rotatory a-pinene 2 ). 

 1 20 g. nopinol acetic acid, m. p. 84 to 85 , were subjected to slow 

 distillation by a hydrogen current in portions of 30 g. each, the 

 receivers being changed whenever the temperature of the vapour 

 emitted exceeded 165 . The resultant hydrocarbon was then fract- 

 ionated over sodium. All fractions gave on all oxidation by means 

 of 1 per cent, permanganate, nopinic acid, (m. p. 126 to 127 ), as 

 well as /?-pinene glycol and a keto-acid, m. p. 68 to 99 , (Md — 

 93,2° in a 7, 16 per cent, chloroform solution; semicarbazone, m. p. 205 ; 

 oxime, m. p. 127 to 12 8°). This acid proved to be identical with 

 the 1-pinonic acid prepared by Gildemeister and Kohler 3 ) as well as 

 by Barbier and Grignard 4 ). Mixed with equal parts of d-pinonic acid it 

 also yielded the well-known inactive pinonic-acid, m. p. 103 to 104 . 

 This proves that, besides /?-pinene, 1- a-pinene is also formed from 

 nopinol acetic acid. Attempts to separate the a-pinene in the form of 

 the nitroso-chloride were unsuccessful. In this case also, it was shown 

 that in the case of pinene - fractions of high activity the absence of 

 the nitroso-chloride reaction is no proof of the absence of a-pinene 5 ). 



The research as to the oxidation of active pinene into the active 

 pinonic acids, which has been stimulated by the occurrence of 1-pino- 

 camphone in oil of hyssop 6 ), has led us to endeavour to elucidate 

 the hitherto unsolved questions why the yield of nitroso-chloride from 

 pinene-fractions of high activity is so small, and why the crystallised 

 pinene nitrosochloride has hitherto been obtained in an inactive form 

 only 7 ). These questions are of high importance, especially in the 

 examination of turpentine oils and of essential oils which have been 

 adulterated with turpentine. 



*) Liebig's Annalen 363 (1908) 9; Report November 1908, 172. 



2 ) Liebig's Annalen 368 (1909), 1. 



3 ) "Wallach Jubilee-pub 1. 1909; Report April 1908, 59; April 1909, 120. 



4 ) Compt. rend. 147 (1908), 597; Report April 1909, 120. 



5 ) Comp. Gildemeister and Kohler, Wallach Jubilee public. 1909; also see below. 



6 ) Comp. Report April 1908, 58; April 1909, 120; also compare below, and 

 p. 68 of the present Report. 



7 ) This investigation forms part of E. Gildemeister's and H. Kohler's contribution 

 to the Wallach Jub. publication, p. 414: Uber das Vorkommen von /?-Pinen und 

 1-Pinocamphon im Ysopol und einige Beobachtungen uber Isomerien in der Pinen- 

 reihe. (Vandenhoek & Ruprecht, Gottingen, 1909). 



