Reactions of aminoarylazopyrazoles with active methylene compounds. Part 1: Synthesis of 7‐amino‐3‐arylazo‐6‐cyano‐2‐methylpyrazolo[5,1‐c][1,2,4]triazines

Abstract

In this study, 2‐arylhydrazone‐3‐ketiminobutyronitriles were synthesised and reacted with hydrazine hydrate to afford 5‐amino‐4‐arylazo‐3‐methyl‐1H‐pyrazoles. These compounds were then diazotised and coupled with malononitrile to give pyrazolylazomalononitriles. Thirteen novel pyrazolo[5,1‐c][1,2,4]triazine dyes were synthesised by heating pyrazolylazomalononitriles in glacial acetic acid and characterised by elemental analysis and spectral methods. The effect of varying pH and solvent upon the absorption ability of the dyes substituted with electron‐withdrawing and electron‐donating groups at their o‐, m‐ and p‐position was examined in detail.