Other Synthetic Dyes

Cationic dyes are occasionally used fur blueing or brightening the hair, frequently in combination with a fluorescent dyes. P. Krais discovered the brightening effect in 1929 by impregnation of rayon with a horsechestnut extract known as esculin, a fluorescent glycoside of 6,7-dihydroxycoumarin. Coumarin derivates are still used for wool and fur hair. 

Synthetic mordants are rarely applied. Reactive dyes for hair or suede and soluble sulfur dyes for suede are chosen only for special purposes. Finally organic 

Colour Index International, 3rd ed., 1999, CD-ROM, Clarinet Systems Ltd. (SDC and AATCC), 1999. 

Freeman, A.T. Peters, Colorants for Non-Textile Application, Elsevier, Amsterdam, 2000. 

Graumann, Handbuch der Gerbereichemie, 3. Band/2.Teil, Springer-Verlag, Wien, 1955. 

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As early as 2500 bce m India indigo was used to dye cloth a deep blue The early Phoenicians discovered that a purple dye of great value Tyrian purple could be extracted from a Mediterranean sea snail The beauty of the color and its scarcity made purple the color of royalty The availability of dyestuffs underwent an abrupt change m 1856 when William Henry Perkin an 18 year old student accidentally discovered a simple way to prepare a deep purple dye which he called mauveme from extracts of coal tar This led to a search for other synthetic dyes and forged a permanent link between industry and chemical research... 

Husain Q (2006) Potential applications of the oxidoreductive enzymes in the decolorization and detoxification of textile and other synthetic dyes from polluted water a review. Crit Rev Biotechnol 26 201-221... 

In the 1970s. decertification of the important luod colors FD C Reds 2 and 4 caused much concern among manufacturers of foud dyes. With the possibility that other synthetic dyes would be banned present, attention was turned to the use of natural dyes as food colorants. Many such dyes had hecn in use for hundreds of years until they were replaced by synthetic dyes. 

Disperse and other synthetic dyes can only be taken up by the hair at elevated temperatures, and for this reason the skins must be chrome-tanned. The shrinking temperature of suede has to be at least 20° C higher then the dyeing temperature. No mordant is required, unlike with oxidation dyes, and killing need be far less intensive, too. In actual fact the operation is more hair cleaning than a killing process. The suede portion is not dyed and can be cleaned very easily with standard washing auxiliaries. 

The era of synthetic dyes is credited to Sir William Henry Perkin, who accidentally synthesized the purple dye mauveine in 1856 (at age 18) while trying to make quinine. Mauveine was an inexpensive substitute for Tyrian purple. Chemists soon developed many other synthetic dyes, and by the late 1800s the dye industry had become one of... 

The process was discovered and patented in 1856 by William Henry Perkin, at a time when the wool and cotton industries were enjoying a trade boom and the demand for colorants threatened to outstrip the supplies of natural dyes, mostly vegetable, then available. Crude benzol from the well-established coal-gas and coal-tar distillation industries was commercially available, as were mineral acids, alkalis, bichromates, saltpetre and other materials. Mauveine followed by other synthetic dyes from Perkin Sons, soon became a success. Other, rival pioneers built factories in the UK and Europe and introduced new dyes, the result of their own research work. 

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