Process for preparing 1-aminoanthraquinone having high purity

Abstract

A process for preparing 1-aminoanthraquinone having high purity, which comprises either 1. hydrogenating 1-nitroanthraquinone in an aqueous medium in the presence of a base using a hydrogenating catalyst, and then oxidizing the hydrogenation product, or 2. hydrogenating crude 1-nitroanthraquinone containing dinitroanthraquinones as impurities or crude 1-aminoanthraquinone containing diaminoanthraquinones as impurities in an aqueous medium in the presence of a base using a hydrogenating catalyst, stopping the hydrogenation at a time when the 1-nitroanthraquinone or 1-aminoanthraquinone has been substantially reduced to 1-aminoanthrahydroquinone but the dinitroanthraquinones or diaminoanthraquinones remain substantially unreduced to diaminoanthrahydroquinones, removing water-insoluble materials from the reaction mixture, and then oxidizing the remaining water-soluble residue.

Dependencies are inferred from the claim text.