Max A. Weaver

Heterocyclic diazo components

Abstract Dyes with heterocyclic diazo components have received much attention because of their high tinctorial power and excellent brightness. Historically, dyes prepared from 2-aminobenzothiazoles and 2-aminothiazoles have played a significant role in disperse dye technology. More recently, dyes prepared from various heterocyclic amines including 2-amino-1,3,4-thiadiazoles, 5-amino-1,2,4-thiadiazoles, 5-amino-isothiazoles, 2-aminoimidazoles, 2-aminothiophenes, 3-amino-2,1-benzisothiazoles, and 5-aminopyrazoles have been evaluated as disperse dyes. Some of these dyes offer excellent brightness of shade and are commercially competitive with more expensive anthraquinone dyes. Heterocyclic diazo components have now been used to prepare acid dyes for polyamide carpet fibres, and some of these acid dyes have been shown to have excellent levelling properties. In some cases, new preparative chemistry has been developed for synthesis of the older as well as the newer heterocyclic diazo components.