Hydroxyanthraquinone pigments

A further series of hydroxyanthraquinones were isolated by Raistrick at the same time from Helminthosporium species. These organisms are found on cereals and grasses. When Helminthosporium gramineum, the causative organisms of a leaf stripe disease of barley, was grown on a Czapek-Dox medium it imparted a deep-red colour to the medium. Under some conditions the underside of the mycelial mat was partially covered with dark-red needle-shaped crystals. The main constituent was a trihydroxyanthraquinone, helminthosporin (7.8). Its structure was 

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The class of hydroxyanthraquinone pigments comprises two different groups of compounds metal complexes of hydroxyanthraquinones on the one hand and metal salts of hydroxyanthraquinone sulfonic acids on the other hand. Some of the products are metal chelates. 

This chapter classifies polycyclic pigments by chemical constitution. The resulting classes include aminoanthraquinones, hydroxyanthraquinones, heterocyclic and polycarbocyclic anthraquinone pigments. 

Benzoylation of l-amino-4-hydroxyanthraquinone affords a bluish red pigment, which is known as Pigment Red 89,60745 ... 

Both groups have lost most of their commercial importance as pigments. There is one derivative of hydroxyanthraquinone sulfonic acid which is used to some extent. This is the reddish violet Pigment Violet 5 1,58055 1, which has the basic structure 89 ... 

Metal complexes of hydroxyanthraquinones are now only of historical interest in the dyestuffs and pigments field. Despite the very attractive shades and extremely good fastness properties of dyeings produced on cotton using the mordant technique with dyes of this type, they have been... 

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