ON OUR PRESENT KNOWLEDGE OF AROMATIC DIAZO-COMPOUNDS. 19 f 



and possesses all the properties of a true metallic salt ; it is very soluble, 

 and its solution is an electrolyte. Moreover, the double salt condenses 

 with /3-naphthol and is converted into the yellow s^/'^-diazo-cyanide by the 

 action of alkaline solutions. 



These results show that diazotised /j-anisidine gives rise to the 

 three cyanides demanded by the stereochemical hypothesis 



R.N.CX KN R.N 



N CN.N N.CN 



colourless soluble coloured labile coloured stable 



electrolyte. non-electrolyte. non-electrolyte. 



The opposite view only accounts for the existence of two isomeric 

 cyanides, one having the constitution of a normal diazonium salt, and the 

 other that of a diazo-cyanide of the zsodiazo-series. 



The syn- and awii-diazo-cyanides cannot be regarded as diazonium salts 

 comparable with those of the mineral acids, for on the one hand they are 

 non-electrolytes, dissolving only sparingly in water, and on the other they 

 are distinctly coloured substances, readily soluble in the organic solvents. 



Their colour confirms the assumption that they contain the group 

 N=N, in common with azo-compounds. The criterion of colour must, 

 however, be applied with caution, for the sjjn- and rt?i^j-alkali salts 

 derived from diazotised sulphanilic acid are colourless. 



Attempts made to obtain, in a state of purity, syn- and an^i-diazo- 

 derivatives containing other radicles in the place of cyanogen have not 

 proved successful. 



The diazonium salts or the alkali an^i-diazo-oxides, when treated with 

 the alkali phenylmercaptides, yield diazo-thioethers, which do not 

 condense with /3-naphthol, and are accordingly taken to belong to the 

 anti-series, 



R.N 



N.S.CgHs. 



Only in the case of ^j-chlorobenzenediazothiophenyl ether was an explosive 

 intermediate compound observed which may possibly be a syw- derivative. 

 Phenol-^j-diazo-hydroxide, HOC|;H,N OH, and hydrogen sulphide yield 

 a hydrosulphide, HOCgH^.Nj.SH, H2S, which is possibly an anti-dia,zo- 

 derivative.' 



By treating ^j-nitrobenzenediazonium chloride with hydrogen sul- 

 phide, Bamberger - obtained three products : — (i) a hydrosulphide 

 NOaCoH^NoSH, H2S, or N02CeH4N(SH).NH.SH, which, like the pre- 

 ceding thio-derivatives, does not couple with phenol ; (ii) a very 

 explosive monosulphide (NO C,3H4N.;)2S, condensing with phenols and 

 decomposing in benzene at the ordinary temperature to yield yj-nitro- 

 diphenyl, hydrogen sulphide, and nitrogen ; (iii) a stable disulphide 

 (NO C,3H4N2)2S.2, which slowly couples with the phenols, and is decom- 

 posed by benzene or toluene. The monosulphide is probably a syn-diazo- 

 derivative, whilst the disulphide is considered to be an iso-{anti)-disizo- 

 compound. 



Diazo-anhydrides. — The isomeric alkali diazo-oxides differ in their 

 behaviour towards cold dilute acetic acid, the aw<i-diazo-oxides giving rise 



» Ber., 1895i 28, 32S7, 5 Ber., 1896, 29, 272, 



