Vat dyes containing anthraquinone with fused heter
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Vat dyes containing anthraquinone with fused heterocycic systems:-
A typical example of this type of vat dyes is Indanthrene Yellow 4GK a pyrimidanthrone derivative. This dye, is prepared from 1. 5-diaminoanthraquinone obtained by the dinitration of anthraquinone, separation of 1,5-dinitroanthraquinone. 1, 5-Diaminoanthraquinone is condensed with 2, 5-dichlorobenzoylchloride to for 1-amino-5-(2', 5'-dichloro)-benzamidoanthraquinone which is then converted to the dye having 1, 9-pyrimidinoanthraquinone structure. The reagent used for this conversion is formamide or the mixture of cyanamide, hydrochloric acid and cupric chloride etc. or the free amino group can be first converted to the formyl derivative and subsequently cyclised with ammonia or ammonium salts to get the dye.
