176 



REPORT— 1903. 



A systematic investigation of the nitro-bromo-keto- compounds formed 

 by the action of nitric acid on the bromo-^S-naphthols has led to the 

 important discovery that whereas most of these substances are of normal 

 composition — for instance, 



NOaBr 



II 



NO2 Br 



III 



Br 



Br 



IV 



others can only be obtained in association either with acetic acid alone or 

 with water of hydration. Thus : 



NO, Br 

 \/ OH 



NO2 Br 

 Br 



OAC + 2H2O 

 Br 



A similar addition of acetic acid takes place in the case of the keto-bro- 

 mides {infra) but apparently not in the case of the keto-chlorides. These, 

 however, as Zincke's researches show, in a few cases combine with alcohol. 

 Generally speaking, the nitro-bromo-keto- compounds increase in 

 stability as the number of bromine atoms increases, so that, whilst the 

 compound I, for instance, begins to decompose slightly above 0° the 

 compound II is so stable that it may be left exposed during several 

 months in the air at the ordinary temperature without undergoing change. 

 But that structure and not merely the proportion of bromine present 

 in the compound largely determines stability is shown by the fact that, 

 for example, the compounds represented by the formulse 



NO2 Br 



VII 



and VIII 



Br'\..^^\v^Br 

 although rich in bromine rapidly decompose at the ordinary temperature. 



