Other Aminoanthraquinone Pigments

As a class, these pigments include 1-aminoanthraquinone compounds which bear free amino groups, and also derivatives in which the primary amino group is substituted by an aryl or a heteroaryl moiety. Only very few representatives are industrially important. 

Formation of C—C links in the anthraquinone molecule, especially substitutions with aryl moieties, proceed via copper-catalyzed nucleophilic exchange of halogenated anthraquinone compounds. These methods include dimerization of 1 -aminoanthraquinone. 

Pigment Red 177, a red pigment which is listed in the Colour Index under Constitution No. 65300, has the chemical structure of 4,4 -diamino-1,1 -dianthra-quinonyl (84) [6]  

Simultaneously with Hansa Yellow G, compound 84 was first described as early as 1909 by Farbenfabriken Bayer. Its preparation starts from l-amino-4-bro-moanthraquinone-2-sulfonic acid (bromamine acid) 85. Dimerization is achieved through the Ullmann reaction, i.e., treatment with fine-grain copper powder in dilute sulfuric acid at 75°C. The separated intermediate, the disodium salt of 4,4 -diamino-l,l -dianthraquinonyl-3,3 -disulfonic acid 86, is heated to 135 to 140°C in the presence of 80% sulfuric acid in order to cleave the sulfonic acid groups [7]  

The result is a bluish red pigment, the only one among the commercial products which possesses free amino groups. 

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P.R.264 provides bluish red shades, which are similar to those of P.R.177, an aminoanthraquinone pigment. The fastness properties are similar to the other types of the DPP pigment class. The commercially available grade is distinguished... 

Other anthraquinone/azo pigments are obtained by coupling 1-aminoanthraquinone derivatives onto bis-quinazolinone methanes with the following chemical structure 82 ... 

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