Synthesis of Some New 5-Arylazothiazole Derivatives as Disperse Dyes for Dyeing Polyester Fibers

A series of 5-arylazo-2-(arylidenehydrazino)-2-thiazolin-4-one dyes 3 and 4 was prepared by cyclocondensation of hydrazonoyl bromides 2 with various thiosemicarbazone derivatives 1. While the synthesis of 3-amino-N-(5-arylazo-2-thiazolyl)-thieno[2,3-b]pyridine-2-carboxamide dyes 8 was achieved by the reaction of 2-(N-chloroacetyl)-5-arylazo-thiazole derivatives 5 with 4,6-dimethyl-2-mercaptonicotinonitrile followed by heterocyclization of the obtained sulfide derivatives 7 in a solution of ethanol containing sodium ethoxide. These dyes were applied as disperse dyes for dyeing polyester fibers and their characteristics and fastness properties have been measured. The dyed fibers exhibit very good to excellent washing, perspiration and sublimation fastness properties, with little variation in good to excellent rubbing and light fastness.