Synthesis of Disperse Dyes from Pyridone and Resorcinol Coupled to Diazotized 2-Amino-4-chloro-5-formylthiazole and Application to Polyester

The aim of this study was to synthesize disperse dyes in the derivative of 2-amino-4-chloro-5-formylthiazole by conventional diazotization and couplings with pyridone and resorcinol. The dyes were characterized by visible absorption spectroscopy, IR spectral studies, and 1H and 13C NMR. The pyridone and resorcinol substituted dyes exhausted well with good depth on 100% polyester fabrics with a shade of brown and purple colours, respectively. The heteroatom and the intrinsic conjugation in the thiazole structure results in high bathochromic shifts and lead to brightness of shades. The dyed fabrics showed very good to excellent wash fastness and moderate to good light and perspiration fastness properties. 1. Introduction Textile dyes such as indigo can be derived from natural sources, while others such as disperse dyes which are meant for specific applications are obtained by synthesis. The dyes are classified according to their chemical constitution or method of application [1]. According to the colour index [2], disperse dye is a class of sparingly water soluble dyes originally introduced for dyeing cellulose acetate and usually applied from fine aqueous dispersion. Disperse dyes have also been defined as sparingly water soluble, nonionic dyes applied to hydrophobic fibres from aqueous dispersions [3]. Disperse dyes are classified as either nitroarylamine, azo, or anthraquinone. Almost all contain amino (NH2) or substituted amino groups but do not contain solubilizing groups such as sulphonic acid (SO3H) groups. The most dominant group of disperse dyes is the azo disperse dyes which account for over 70% of all disperse dyes manufactured. Disperse dyes, though originally developed to dye cellulose acetate, are now usefully applied to other hydrophobic fibres such as polyester [4]. Although more hydrophobic than cellulose acetate, polyester is more readily dyeable by some of the dyes developed for acetate using different techniques of dyeing at high temperature or in the presence of swelling agents or carriers [5]. This study focused on synthesis of disperse dyes in the derivative of 2-amino-4-chloro-5-formylthiazole by conventional diazotization and couplings with pyridone and resorcinol. The 2-amino-4-chloro-5-formylthiazole provides the base heterocyclic diazo component [6–9]. Pyridone derivatives are relatively recent heterocyclic intermediates for the preparation of azo dyes because azo pyridone dyes produce bright hues and are suitable for dyeing polyester fabrics. Although synthesis and condensation of the formyl group in the derivatives of