Classification of Dyes by Chemical Structure

Abstract

There are several ways to classify dyes. For example, they may be classified by fiber type, such as dyes for nylon, dyes for cotton, dyes for polyester, and so on. Dyes may also be classified by their method of application to the substrate. Such a classification would include direct dyes, reactive dyes, vat dyes, disperse dyes, azoic dyes, and several more types. These classifications are more suited to a book aimed at the technology of the application of dyes to a substrate rather than one dealing primarily with the synthesis and chemistry of dyes. Griffiths1 has classified dyes on a purely theoretical basis based upon the electronic origins of color. Only four classes are defined, namely: 1. Donor-acceptor chromogens. 2. Cyanine-type chromogens. 3. Polyene chromogens. 4. n → π* chromogens.