The possible tautomeric forms of arylazo derivatives could be
set out as outlined in Fig. 2.
There are referred to as the CH azo form (A), the NH azo form (B)
and the cyanohydrazone form (C). The presently available data indicate
that the tautomeric structure 2 or 4 is the chelated hydrazone
form (C). It was therefore considered worthwhile preparing arylazo
compounds containing the pyridine ring to evaluate their biological
activities. In this investigation, ten N-arylpicolinohydrazonyl
cyanides 2a–d and N-arylisonicotinohydrazonyl cyanides 4a–f
were prepared by coupling of 2 and/or 4-cyanomethylpyridines 1
and/or 3 with the appropriate diazonium salt in ethanol containing
sodium acetate. The newly prepared dyes were characterized by
elemental analyses, as well as by spectral analysis