Synthesis of some novel pyrazolo[5,1-c][1,2,4]triazine derivatives and investigation of their absorption spectra

In this study, 5-amino-4-hetarylazo-3-methyl-1H-pyrazoles were diazotised and coupled with malononitrile and ethyl cyanoacetate to give pyrazolylazo malononitriles and ethyl pyrazolylazo cyanoacetate, respectively. Ten novel pyrazolo[5,1-c][1,2,4]triazine dyes were synthesized by heating of pyrazolylazo malononitriles and ethyl pyrazolylazo cyanoacetate in glacial acetic acid. The dyes were characterized by elemental analysis and spectral methods. The solvatochromic behaviour of these diazo dyes in various solvents was evaluated. Substituent, acid and base effects on the visible absorption maxima of the dyes are also reported.