Synthesis of azo disperse dyes with 2-amino-5-phenyl-1,3,4-thiadiazole moiety for dyeing polyester fibre

185-188<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:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">2-Amino-5-phenyl-1,3,4-thiadiazole(II), prepared by condensing benzoic acid (I) and thiosemicarbazide, was treated with salicylaldehyde to give 2-(6'-hydroxy Schiff’s base-1'-yl)-5-phenyl-1,3,4-thiadiazole (III). Various aryl arnines (IVa-t) were diazotised and coupled with the compound III to give 2-(6'-hydroxy Schiff’s base-5'-arylazo-1'-yl)-5-phenyl-1,3,4-thiadiazoles (Va-t). All the compounds, when applied on polyester fibre as 2% shade, showed moderate to good light fastness and good to excellent fastness to washing, perspiration, rubbing and sublimation.