Synthesis of 5-(4-arylazo/hetarylazo-phenyl)-2-hetaryl-3,4-dihydroxythiophene derivatives and their application on polyester fibres as disperse dyes

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:calibri;mso-bidi-theme-font:minor-latin;="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">2-(Benzoxazol-2-yl)-3,4-dihydroxy-5-(4-nitrophenyl)thiophene (<b>Va</b>) and 2-(benzimidazol-2-yl)- 3,4-dihydroxy-5-(4-nitrophenyl)thiophene (<b>Vb</b>) were synthesized from S-(4-nitrobenzyl)thioacetic acid (<b>II</b>) by condensation with diethyl oxalate followed by subsequent treatment with 2-aminophenol (<b>IVa</b>) and 1,2-diaminobenzene (<b>IVb</b>) respectively. The compounds <b>Va</b> and <b>Vb</b> were reduced with zinc-acetic acid to corresponding amino derivatives <b>VIa</b> and <b>VIb</b> and the diazo components derived from <b>VIa</b> and <b>VIb</b> were coupled with a variety of coupling components (<b>VIIIa-f</b>) to result 5-(4-arylazo/hetarylazo-phenyl)-2- (benzoxazol-2-yl/benzimidazol-2-yl)-3,4-dihydroxythiophenes (<b>IXa-f</b> and <b>Xa-f</b>). The compounds <b>IXa-f</b> and <b>Xa-f</b> when applied on polyester fibres gave yellow to red shades with poor to good pick-up, moderate light fastness and good sublimation fastness.</span>