Synthesis of disazo dyes derived from heterocyclic components

In this study, 2-phenylhydrazone-3-ketiminobutyronitrile was synthesised and reacted with hydrazine hydrate and phenylhydrazine to afford the corresponding 5-amino-3-methyl-4-phenylazo-1H-pyrazole and 5-amino-3-methyl-4-phenylazo-1-phenylpyrazole, respectively. Ten novel disazo dyes were then synthesised by diazotisation of 5-amino-3-methyl-4-phenylazo-1H-pyrazole and 5-amino-3-methyl-4-phenylazo-1-phenylpyrazole using nitrosylsulphuric acid, and coupling with 4-hydroxy-6-methyl-2-pyrone, 4-hydroxycoumarin, 3-methyl-1H-pyrazolin-5-one, 3-methyl-1-phenylpyrazolin-5-one and 3-cyano-6-hydroxy-4-methyl-2-pyridone. The dyes were characterised by elemental analysis and spectral methods. The solvatochromic behaviour of these disazo dyes in various solvents was evaluated. Received: 18 May 2005; Accepted: 8 July 2005.