— 134 — 



In his third paper on the constitution of camphene, Aschan 1 ) dis- 

 cusses the experiments in oxidation which he has carried out with this 

 hydrocarbon. Camphenes of different origin, (technical c, c. from iso- 

 borneol, c. from Z-borneol, Kahlbaum's c, c. from Siberian pine needle 

 oil, recrystallised technical c, and c. from Greek turpentine oil) gave the 

 same oxidation-products in constant quantitative proportions. The prin- 

 cipal product formed was camphenic acid, in addition to which cam- 

 phenilone, camphenyl glycol, camphenilic acid and acids soluble in water 

 were generated. For purposes of oxidation, 25 g. camphene was dissolved 

 in 5 g. benzene and diluted with a solution of V 2 liter water and 7,5 g. 

 caustic potash. This mixture was slowly oxidised at ordinary temperature 

 with the oxidation-liquid, which consisted of 64 g. permanganate of 

 potassium in 3,2 liters water. 



The results of his experiments in oxidation lead Aschan to the follow- 

 ing conclusion: "camphene represents an ethylenic complex with the 

 double-bond in the ring, or it is of a tricyclic structure, perhaps with 

 one trimethylene-ring, which opens very readily, producing an ethylenic 

 complex of the above character". 



Aschan's fourth paper 2 ) deals with of the stereomeric camphenic acids. 

 m-Camphenic acid (m. p. 135,5 to 136,5°), obtained by oxidising technical 

 camphene, m. p. 42°, was heated in a sealed tube with a mixture of 

 glacial acetic and hydrochloric acids to 180°. From the reaction-product 

 the author isolated, in addition to unattacked acid, a d,l-trans-camphen\c 

 acid (m. p. 122 to 123°) from which he obtained a diamide, m. p. 231 

 to 232°, and a dianilide, m. p. 165°. He also reduced m-a-bromo cam- 

 phenic acid with zinc and glacial acetic-hydrochloric acid, the result being 

 almost equal quantities of cis- and trans-camphenlc acid. Distillation of 

 the cis-camphenic acid under diminished pressure also resulted in the 

 partial conversion of the cis- into the trans-acid. When distilled under 

 ordinary pressure, cis-camphenic acid is decomposed, an acid C 9 Hi 4 2 

 being formed. 



When camphene is oxidised with hydrogen peroxide changes in its 

 molecular structure are hardly to be expected, hence the results obtained 

 by G. G. Henderson and M. M. J. Sutherland 8 ) when oxidising camphene with 

 the reagent in question are of particular interest. The principal reaction- 

 product was a monobasic acid of the formula C9H15CO2H (m. p. 95°), 

 to which the name camphylic acid was given; in addition a solid acid 

 (m. p. about 70°) and a liquid acid, b. p. 153° (20 mm.) were formed. The 

 constitution of camphylic acid could not be determined, but it appears that its 

 nucleus is different from that of camphene. Of neutral oxidation products, 



i) Liebigs Annalen 383 (1911), 39. 



2 ) Ibidem 52. 



3 ) Journ. chem. Soc. 99 (1911), 1539. 



