A facile synthesis of new monoazo disperse dyes derived from 4-hydroxyphenylazopyrazole-5-Amines: Evaluation of microwave assisted dyeing behavior

Abstract

A series of new monoazo disperse dyes containing pyrazolopyrimidine moieties was synthesized by coupling malononitrile or 3-Aminocrotononitrile with 4-hydroxybenzenediazonium chloride. Treatment of the resulting products with hydrazine hydrate yields the corresponding 4-Arylazoaminopyrazoles, which then react with either 2,4-pentanedione and enaminonitriles or aryl-substituted enaminoketones to give the target pyrazolopyrimidine monoazo disperse dyes. Structural assignments of the dyes were made using both NMR spectroscopic and X-ray crystallographic methods. A high temperature dyeing method, by microwave irradiation, was employed with polyester fabrics. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing and perspiration fastness levels. © 2012 by the authors.