Preparation and characterisation of novel methylsulfanylpyrazolopyrimidines as heterocyclic dyes from ketene dithioacetals

Purpose - This paper aims to synthesize some new heterocyclic disperse azo dyes and their application in dyeing of polyester and polyamide fabrics. Design/methodology/approach - Pyrazolopyrimidine derivatives containing arylazo function by the reaction of 3,5- diaminopyrazole with ketene dithioacetals were prepared. The prepared dyestuffs are established using elemental analysis, IR measurements, H-1-NMR and Mass spectra. Findings - 2,5-diamino-3-ar azo-N-aryl-6-carboxamide-7-methylthio-pyrazolo[1,5-a]pyrimidine have been synthesized by the simple method. The dyed fabrics have a very good (4-5) to excellent (5) results toward washing, perspiration, and rubbing fastness properties. The dyes are superior in terms of preparation and fastness properties. Research limitations/implications - The disperse azo dyes used in this paper were synthesized via a step-wise pathway leading to the new azo dyes. In addition, the variations in substituents and sites of location on the heterocyclic moiety could also be studied. Practical implications - The new azo dye systems based on substituted pyrazolopyrimidine provided a series of azo dyes with improved dyeing properties. The dyes are superior in terms of yield, purity, colour strength, and fastness properties and will lead to valuable achievements for commercial production. Originality/value - The synthesized disperse azo dyes are superior in terms of preparation, yield, purity and fastness properties.