— 197 — 



liquor it renders back 50°/o of diketonic ester, while 40°/o of the body is 

 further split up into /?, /?-di methyl glutaric acid. According to Blanc and 

 Thorpe such a conversion is hardly consistent with the formula of an ester 

 which has been methylated in a carbon atom. Hence Komppa was mistaken 

 when he assumed that by further reduction and hydrolysis he had obtained 

 camphoric acid from this body. 



In the discussion following the paper (which was read before the 

 Chemical Society in London), Pickles asked whether the methoxyl-deter- 

 mination of the body melting at 85 to 88° had been carried out, and 

 suggested the possibility that, accepting Komppa's formula, the methyl 

 group of the carbon atom next to the carboxymethyl group might have 

 wandered further off in the course of the subsequent treatment, before the 

 body had been identified as the O-methylated ester. To this, Thorpe 

 replied that in view of the readiness with which diketo-apocamphoric 

 acid ester had been formed again under treatment with cold alkalies, 

 Blanc and himself were of opinion that the repetition of Komppa's reduc- 

 tion with sodium-amalgam in alkaline solution served no purpose. 



Natural camphor is strongly dextrorotatory, but the synthetic product 

 is usually either inactive or only faintly active. Darmois l ) has found that 

 the rotation of several commercial samples ranged from — 2° to 7° (from 

 French turpentine oil) to +5° (from American oil). But it is also possible, 

 by the Hesse-Houben method 2 ), to prepare an active synthetic camphor 

 containing, according to Hesse, only traces of isoborneol. Darmois, in 

 his attempts to obtain synthetic camphor of the highest possible activity, 

 took as his starting point pinene hydrobromide instead of pinene hydro- 

 chloride. He prepared the former from the strongly dextrorotatory pinene 

 of Aleppo fir oil (Mj +50,5°), converting it into borneol by the familiar 

 method. In crystallising this substance from light petroleum several highly 

 active constituents were obtained, especially when the crude alcohol was 

 fractionated by steam distillation. The following table shows the variations 

 in the rotation: — 



I II III 



Crystal fraction 

 First fraction obtained ( 5 /e of the borneol) + 4,4° +2,5° —2,5° 

 Last „ „ C/e „ „ „ ) +10,3° +5,7° -2,5° 



The borneol was therefore not homogeneous, but a mixture of a dextrorotatory 

 body with a more readily volatilising and soluble part, and it therefore 

 behaved like a mixture of d-borneol and 1-isoborneol. Oxidation with 

 chromic or nitric acid gave rise to a highly active d-camphor, of which 

 the index of rotation, [«]j about +49°, pointed to a content of about 7°/o 



: ) Compt. rend. 150 (1910), 925. 



2 ) Comp. Report October 1906, 112, 113. 



