Quantivalence of Oxygen. 405 



The formula proposed about the same time by the author 

 for the /3-naphthylamine azo-derivatives was analogous to 

 Liebermann's, and was based on the assumption that the com- 

 pounds in question no longer contained the NH 2 -group, 

 because it was thought at the time that they were non-basic 

 and could not be diazotized. The formula was written : — 



The observations which led Zincke to propose a modification 

 of the above formula are as follows : — By the action of phe- 

 nvlhydrazine on a-naphthaquinone a substance is obtained 

 which is identical with that obtained by the action of diazo- 

 benzene salts on a-naphthol. According to its mode of for- 

 mation this substance may be either benzeneazo-a-naphthol 

 (I.) or a-naphthaquinone-hydrazone (II.) *". 



/OH(a) ,0 (a) 



CloH6 ^ 2 .C 6 H 5W CloH6 ^.NH.C 6 H 5 .. W 



I. II. 



The last formula may, of course, be written on the ketone 

 type of the quinone : — 



/O 



\N.NH.C 6 H 5 



AVhich is the true formula of the compound in question does 

 not appear to be decided by Zincke. In his first paper he 

 suggests that the hydrazone is first formed and that this 

 becomes transformed into the azo-compound by intramolecular 

 change ; but in his latest communication on this subject + he 

 appears to suggest that the substance may be capable of existing 

 in both forms. With regard to the hydrazone of /3-naphtha- 

 quinone, it has been found that this compound is isomeric 

 and not identical with benzeneazo-/3-naphthol. Nevertheless 

 Zincke regards both compounds as hydrazones, the isomerism 

 being considered as the result of position only : — ■ 



6x N.NH.C 6 H 5 ...(/3) 6 \) (0) 



Hydrazone. Azo-compound. 



* This is the nomenclature recently proposed by E. Fischer, Ber. 1888, 

 p. 964 

 t Ber. 1888, p. 2202, note. 



