Synthesis of novel tetrasubstituted thiophenes based dye using sodium a-cyanoketene dithiolates as starting materials

Abstract

Purpose – The study aims to synthesise new thiophene-based dyes by an efficient method using sodium a-cyanoketene dithiolates as starting components for synthesis of tetra-substituted thiophenes, which act as a coupler for the synthesised dye. The synthesised dyes are applied for printing polyamide and polyester fabrics using the screen printing technique. Design/methodology/approach – Treatment of 1 with carbon disulfide in alkaline medium forming disodium salt 2, which act as starting point for heterocyclisation to prepare these dye stuff 7. Sodium a-cyanoketene dithiolates 2 react with two moles of phenacyl bromide derivatives, forming alkylsulfanylthiophenes which react with the diazonium salt, forming the target dyestuff. These prepared dyes are used to print polyamide and polyester fabrics by using a synthetic thickener in the printing paste using screen-printing techniques. Findings – The structure of synthesised dyes were established and confirmed for the reaction products on the basis of their elemental analysis and spectral data (IR and 1H-NMR). The suitability of the prepared dyestuffs for screen printing on polyamide and polyester fabrics has been investigated. The prints obtained from dyes possess high colour strength as well as excellent overall fastness properties. Research limitations/implications – The diazo coupling reaction of the starting tetra-substituted thiophene 5 with diazotised aromatic amines resulted in the formation of the corresponding dye. The synthesised dyes were utilised in preparing a paste for polyester and polyamide fabric printing. In addition, both of the variations of the substituents on the synthesised dyes and the fastness properties were also studied. Practical implications – The synthesised dyes are superior in terms of yield, purity, colour strength and fastness properties, which lead to valuable achievements for commercial production. Social implications – The synthesised dyes are superior for application in fabrics. Originality/value – The synthesis for novel thiophene-based dye stuff for application in printing properties on polyester and polyamide fabrics and study their fastness properties.