412 Prof. Raphael Meldola on the 



naphthol. I am disposed to believe that all three substances 

 are true azo-compounds and not hydrazones, the change in 

 constitution resulting from the transfer of the H-atom, as 

 suggested by Zincke in one of his earliest papers on this 

 subject *. 



The arguments which tell against the hydrazone formula 

 have already been stated. One other consideration here sug- 

 gests itself. If the group : N . NH . X' were present in the 

 /3-azo-compounds, it might certainly be expected that if X' 

 were made strongly acid by the introduction of N0 2 or other 

 acid radicals, the NH would become a salt- forming group, 

 just as it is in the higher nitro-derivatives of diphenylamine, 

 or in the acid diazoamido-compounds. But this is not 

 the case ; the nitrobenzeneazo-/3-naphthols described by the 

 author (Journ. Chem. Soc, Trans. 1885, pp. 661 & 668) aro 

 quite as insoluble in aqueous alkalies as benzeneazo-/3-naphthol 

 itself. The evidence in favour of such an intramolecular 

 change as is required in the conversion of a hydrazone into 

 an azo-compound has been accumulating since Zincke first 

 put forward the suggestion. Thus Bernthsen found t that, 

 by the action of phenylhydrazine upon acridyl-aldehyde, an 

 azo-compound and not a hydrazone is formed. He suggests 

 that the hydrazone undergoes intramolecular transformation, 

 probably by the formation of an intermediate compound in 

 accordance with the views of Victor Meyer : — 



C 6 H 5 .NiHj-N:CH.C 1 3H 8 N=C 6 H 5 .N:N.CH 2 .C 13 H 8 N + H 2 0. 



' jHOJ H 



It must in future be recognized that the grouping 

 C 6 H 5 .NH.N:C: 



may become transformed into C 6 H 5 . N : N . CH : The con- 

 verse change is now known, through the researches of Japp 

 and KlingemannJ, to take place in many reactions ; e. g. the 

 formation of phenylhydrazonepyruvic acid by the action of 

 diazobenzene salts on ethylic sodiomethacetoacetate. 



The formation of the benzeneazo-naphthols by the action of 

 phenylhydrazine upon the quinones is therefore a reaction 

 which has now fouud a parallel, Benzeneazo-a-naphthol is a 

 true oxyazo-compound and requires no further consideration. 

 The existence of two benzeneazo-/3-naphthols is, as shown by 

 Zincke, due to position isomerism, only the formulae would 



* Ber. 1884, p. 3026. t Ber. 1888, p. 743. 



% Proc. Chem. Soc. Dec. 15, 1887 ; Ber. 1887, pp. 3284 & 3398 ; Journ. 

 Chem. Soc, Trans. 1888, p. 519. Also Victor Meyer, Ber. 1888, p. 11 ; 

 and R. Meyer, Ber. 1888, p. 118. 



