Notes on scientific research. 103 



so many different melting-point values (118 to 135 ) 1 ), for the so-called camphene 

 hydrochloride. 



The identification and quantitative estimation of the camphene hydrochloride may 

 be based upon its behaviour, in the cold, towards seminormal alcoholic lye. The 

 chloride can easily be titrated with this lye. By means of a simple mode of titration 

 the authors investigated the transformation of the camphene hydrochloride into iso- 

 borneol, and they observed that this transformation is never completed and that a state 

 of equilibrium is established between isobornyl chloride and camphene hydrochloride, 

 and possibly also pinene hydrochloride. As a matter of fact isobornyl chloride changes 

 when heated for a short time partly into camphene hydrochloride. These two bodies 

 behave, therefore, like tautomeric compounds. The transition of the camphor series 

 into the camphene series may be traced back to the same cause. These transformations 

 are probably true intramolecular displacements of the atoms, that is to say, there is 

 a direct change of place between the alkyl radicle and the halogen atom. 



As regards the fact that the camphene obtained from active or inactive borneol, 

 and the isoborneol from camphene are always inactive, the authors suggest the following 

 supposition. In addition to the main reaction isoborneol ±^: camphene hydrate ^"^ 

 camphene, there is a subsidiary reversible reaction, i. e., the formation of tricyclene 

 from camphene hydrate, and the racemisation of the camphene and of the isoborneol 

 takes place indirectly, via tricyclene. This hypothesis would also account for the 

 easy racemisation of the camphene by acids, as well as for the occurrence in camphene 

 of small quantities (about 0.4 per cent.) of tricyclene (obtained from isoborneol). The 

 transformations taking place in the absence of acids must, On the other hand, lead 

 to optically-active preparations, since in this case the reversible secondary reaction 

 of the tricyclene-formation would be absent. Thus Lafont 2 ) obtained from camphene 

 optically-active isoborneol, and the experiments of Ipatiev 3 ) justify the expectation of 

 the preparation of an optically-active camphene from isoborneol. 



Bornylene. — Since it had not been possible in cases of direct scission of bornyl 

 derivatives altogether to avoid the Wagner 4 ) transformation and to obtain bornylene 

 free of camphene and other by-products, L. Ruzicka 5 ) has worked out a process by 

 means of which he obtains, with the help of bornyl trimethylammonium hydroxide, 

 pure bornylene (m. p. Ill to 112°; uncorr., in non-recrystallised crude products). 



The bornyl trimethylammoniumiodide (m. p. 245°, uncorr.) prepared after Leuckart 6 ) 

 and Forster 7 ), was by treatment with silver oxide converted into the hydroxide and 

 further, by distillation in a high vacuum (one C— CH 



eighth mm.), at least partially into bornylene 

 (m. p. Ill to 112°). By means of methyl 

 iodide an isobornyltrimethylammonium iodide 

 (m. p. 278 to 279°, with decomposition) could c 



be prepared from the by-products of this 

 reaction. The author presumes that we have CH 



here to deal with an Ordinary borneol-iso- Bornyltrimethylammoniumhydroxide. 



borneol isomerism, and that the iodide, from which he started, already represented 

 a mixture of stereo-isomerides, corresponding to the bornylamine of Forster 8 ). 



C(CH 3 ) 2 



CH.N(CH 3 ) 3 -OH 

 CH 2 



: ) Gildemeister and Hoffmann, The Volatile Oils, 2 nd ed., vol. I, p. 304, record melting points between 

 142 and 164 o. _ *) Ann. chim. [6] 15 (1888), 151, 172. — *)'Berl. Berichte 45 (1912), 3211. — 4 ) Cf. Report 

 1919, 115. — B ) Helvet. chim. acta 3 (1920), 748. — 8 ) Liebig's Annalen 269 (1892), 347. — 7 ) Journ. chetm. 

 Soc. 75 (1899), 945. — 8 ) Journ. chem. Soc. 77 (1900), 1152. 



