Alizarin Commercial synthesis

Levinstein, deeply moved by Caro s endorsement of his actions, supported Caro s decision to give up his leading role at BASF that had stretched back over two decades and witnessed some of the greatest chemical inventions of that period. One of them, the commercial synthesis of alizarin, had in 1869-70 brought BASF into... 

Technical Observations Alizarin was the first naturally occurring coloring matter which was successfully prepared synthetically on a commercial scale. This synthesis was a triumph for the then young coal-tar dye industry, and for a long time alizarin was its most important product. The world production of alizarin (as 100 per cent material) was about 2,800,000 kilograms yearly, of which the Badische A.S.F. supplied 2,000,000 kilograms. In more recent times, the consumption of alizarin has been greatly reduced as a result of the competition of more easily applied red dyes of the azo series, especially some of the equally fast naphthol AS combinations. 

In this synthesis it is interesting that it is the mono-sulphonic acid of anthraquinone and not the di-sulphonic acid which is the intermediate product. Other syntheses have been used commercially. Anthraquinone may be converted into alizarin without sulphonation by treating it with a mixture of sodium hydroxide, potassium hydroxide and sodium chlorate and heating to 200°. Also electrolytically by passing a current through a mixture of anthraquinone and fused potassium hydroxide. 

Industrial Importance.—The synthesis of alizarin by Graebe and Liebermann was the first case of a common natural dye being prepared in the laboratory. As the synthesis starts with anthracene, a substance obtained in good yields from coal tar, it affords at once a cheap commercial source for the synthetic preparation of a natural product. Hardly any synthesis that has been worked out in the laboratory has had such an immediate effect upon industry as this one, and in addition to this it exerted a strong influence upon similar syntheses of other dyes. In 1868 Turkey red was a very common and valuable dye and the growth of the madder plant, in France especially, was an important industry. In their original paper Graebe and Liebermann make this statement ... 

Perkin s dye synthesis was the beginning of the coal-tar dyestuffs industry. He later developed and manufactured magenta (violet dye) and alizarin (a red dye). The rapid acceptance of these dyes by fabric manufacturers was demonstrated by the fact that annual alizarin production reached 220 tons per year by 1871. At age 37 and a wealthy man, Perkin sold his commercial holdings and devoted the rest of his life to pure chemical research. 

Advances were made in all three directions. The first substantive (or Direct) cotton dye Congo Red (i.e. with which a mordant was not needed) appeared in 1884 (Bottiger) followed by Primuline (A. G. Green, 1887). Alizarin was produced artificially as early as 1869 and production of the natural product gradually declined. The synthesis of indigo by a route which was economically viable proved very difficult. Baeyer determined the structure in 1883 and a commercially successful process appeared in 1897, followed by the phenygly-cine/sodamine process of 1901. 

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