A facile synthesis of new monoazo disperse dyes derived from 4-hydroxyphenylazopyrazole-5-amines: evaluation of microwave assisted dyeing behavior.

Alya M Al-Etaibi, Morsy A El-Apasery, Maher R Ibrahim, Nouria A Al-Awadi

Index: Molecules 17(12) , 13891-909, (2012)

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Abstract

A series of new monoazo disperse dyes containing pyrazolopyrimidine moieties was synthesized by coupling malononitrile or 3-aminocrotononitrile with 4-hydroxy- benzenediazonium 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.