Topic: Dyes, Industry, and Science

[chenhongxia]

Dyestuffs were central to the first Industrial Revolution, from the late eighteenth century, based on the production of and trade in textiles. This encouraged chemists to investigate the composition of natural dyes. They extracted the colorant in madder and gave it the scientific name alizarin. Dyes also played a prominent role in the second Industrial Revolution, commencing around 1870, when the quest for synthetic colorants led to the development of science-based industry.
The first of the modern synthetic dyes was invented in London in 1856 by the chemist William Henry Perkin when he was still a teenager. His product was first sold as Tyrian purple, but from 1859 on it was known as mauve, from the French word for the mallow flower. It was made from coal tar, the waste product of the coal gasification process. The coal-tar product benzene was converted in three steps to the dye. Perkin's teacher was the German chemist August Wilhelm Hofmann, who began research to identify the chemical constituents of the new coal-tar or "aniline" dyes. Chemistry in Germany was highly developed at this time, and many Germans journeyed to England to work in the new synthetic dye industry. Starting in the mid-1860s, they returned home, armed with the latest science and technology. The industry soon moved to Germany and Switzerland.
Particularly significant was the production of artificial alizarin red (in 1869), mainly in Germany, and indigo (1897), only in Germany. These synthetic products destroyed the trading monopolies in natural dyes by displacing the large-scale cultivation of madder and indigo. The other new dyes had no analogs in nature. In 1875 the dye chemist Otto N. Witt proposed a theory of color and constitution that is still used to explain how certain arrangements of atoms, called chromophores, give rise to color. Other groups called auxochromes enable the bonding to fiber and modify the color.
The development of the synthetic dye industry led to the emergence of classical organic chemistry. Its application in industry was rapid. From the end of the nineteenth century the intermediates employed in the manufacture of synthetic dyes were used to make pharmaceutical products such as aspiri Some synthetic dyes exhibited bactericidal properties; they were called medicinal dyes. Sulfonamides, drugs introduced in the 1930s, are based on research into dyestuffs and their intermediates. Less fast dyes have made color photography possible. Indigo is not fast to light and washing, and soon gives a faded effect. Since the 1960s that property has been used to advantage in fashionable denims.
The modern U.S. chemical industry emerged in 1915, when supplies of dyes were cut off by Germany, which required dyes and their intermediates for military purposes, including the manufacture of explosives, and also by the British blockade on German shipping. From the 1970s the by then mature industry declined in Europe and the United States, in part because of environmental difficulties facing dye manufacturers, such as the pollution of surface waters.