ON THE CONSTITUTION OF CAMPHOR. 301 



The a-mono-halogen derivatives, such as a-monobromocamphor, on 

 treatment with oxidising agent are converted into camphoric acid 



/CHBr /COOH 



^CO ^COOH 



The a- di- derivatives are only oxidised with great difficulty, and on 

 treatment with alkalis are usually converted into the a-j^oio-derivatives. 

 Thus when a-bromocamphor is chlorinated it yields a mixture of two stei'eo- 

 isomeric bromochlorocamphors, both of which are converted into a-chloro- 

 camphor on treatment with alkali, so that both halogen atoms must be 

 attached to the same carbon atom ' 



/CHBr /CClBr /CHCl 



C.H.y I -^ C«H, / I -> C«H, / I 



^co \co ^co 



a-Bromocainphor. ao-Bromochlorocamphor. a-Chlorocamphor. 



Again the a-monohalogen derivatives when heated with nitric acid 

 are converted into nitroderivatives, which yield a-nitrocamphor on treat- 

 ment with alkali ; nitrocamphor when heated with acids is converted into 

 the oxime of camphoric anhydride. Moreover the a-nitrocamphors exist 

 in tautomeric forms, characteristic of nitrocompounds containing the 

 group >CH.N02.2 



,CHBr .CBr.NO, ^CH.NO 



2 



--CO ^co ^co 



/O : N.OH 



^co/ 



(ii) Camjjhor yields Alkylidene Derivatives on Treattnent with Alde- 

 hydes. — When camphor is acted on by, for example, benzaldehyde, in 

 presence of sodium, condensation occurs, and a benzylidene camphor is 

 iinally obtained. Its constitution must be expressed by the formula 



.C : CH Ph 



^CO 



as only ketones containing the group — CH2.CO — are known to react in 

 this way. 



(iii) Cam2ohor is capable of takitig part in the Claisen Reaction. — The 

 Claisen condensation, which is capable of application among saturated 

 ketones only to those containing the group — CH2 . CO — , is applicable to 

 camphor under certain conditions, and isonitro-, and hydroxy-methylene 

 camphor, &c. are readily obtained. These can only be expressed by the 

 formulae 



/C : N.OH /C : CH.OH 



C8H,4< I and C^H, / | 



\co \co 



' Lowry, Tram. Chem. SoctZ, 5G9. 

 - Ibid., 73, 986. 



