404 Prof. Raphael Meldola on the 



With respect to the azo-derivatives of the /3-series, with 

 which I propose to deal in the present paper, the most striking 

 feature is the greater stability and the insolubility in aqueous 

 alkalies of the azo-/3-naphthol compounds, a character to which 

 attention was first directed by Liebermann * as the result of 

 an observation made by Pfaff. So also the corresponding /3- 

 naphthylamine azo-derivatives differ from the a-compounds 

 in many particulars. The latter are distinctly basic and, as 

 previously stated, are capable of being diazotized, these 

 properties pointing to the presence of the NH 2 -group in the 

 compounds in question. The ^-derivatives, on the other hand, 

 are less basic ; they form salts only with great difficulty f and 

 are diazotized with much less facility than the a- compounds J. 

 There are other points of difference between the two series to 

 which attention may also be directed. Thus the a-naphthol 

 azo- compounds are readily alkylated §, while the corresponding 

 /3-naphthol derivatives can only be imperfectly alkylated || ; 

 the former can also be easily acetylated, while the latter require 

 prolonged boiling with acetic anhydride and anhydrous sodium 

 acetate If. 



The first attempts to write the formulae of the azo-compounds 

 of the /3-series on a different type to those of the a-series were 

 made by Liebermann"*"*, the author ft, and Zincke and Binde- 

 wald J J. It is proposed now to consider briefly these different 

 formulas. The insolubility in alkalies of benzene-azo-/3-naphthol 

 led Liebermann to the conclusion that this and analogous 

 compounds no longer contained hydroxyl, and he suggested a 

 formula which may be generalized as follows : — 



7 NH(«) X 

 ^H 6X()(/3)/ N.X 



[In this and succeeding formulas X may stand for any 

 aromatic radical. The position of the azo-group (or its 

 representative) is in these compounds known to be in the ct- 

 ortho-position with respect to the other substituent.] 



* Ber. 1883, p. 2858. 



+ Zincke and Kathgen, Ber. 1886, p. 2482 ; Zincke and Lawson, Ber. 

 1887, p. 2896. 



t Meldola, Journ. Chem. Soc, Trans. 1884, p. 117 ; Nietzki and Goll, 

 Ber. 1886, p. 1281 ; Zincke and Lawson, Ber. 1887, p. 2896. 

 § Zincke and Bindewald, Ber. 1884, p. 3026. 

 II Weinberg, Ber. 1887, p. 3171. 



% Meldola and East, Journ. Chem. Soc, Trans. 1888, p. 460. 

 ** Ber. 1883, p. 2858. 

 tt Journ. Chem. Soc, Trans. 1884, p. 117. 

 U Ber. 1884, p. 3026. 



