Organic Dyes and Pigments

Abstract

Color, which contributes so much to the beauty of Nature, is essential to the attractiveness and acceptability of most products used by modern society [1]. As long ago as the 25th century BC man colored his surroundings and clothes using a limited range of natural colorants of both animal and vegetable origin. Alizarin (18)1 extracted as the glycoside rubierythric acid from madder, was used by the ancient Egyptians and Persians, the use of indigo (16) obtained from Indigofera dates back to 3000 BC, and Tyrian Purple (6,6′-dibromoindigo), prepared from the sea snail Murex brandaris, has been used since the Roman era. However, the preparation in 1856 of the first synthetic dyestuff, mauveine (12), by Perkin gave birth to the development of many other important sectors of the modern chemical industry. Compared with natural dyestuffs, synthetic colorants are better able to meet the increasingly rigorous technical demands of the present day in terms of stability, fastness, etc. Color can add not only aesthetic appeal, but frequently provides an almost irreplaceable safety feature (traffic lights and signs, drug identification, control systems) [2].