GB1462020A - Preparation of 1-aminoathraquinone - Google Patents

Abstract

1462020 Preparation of 1-Aminoanthraquinone by auto-reduction MITSUI TOATSU CHEMICALS Inc 1 April 1975 [2 April 1974 5 April 1974 13 Sept 1974] 13270/75 Heading C4P A process for the preparation of 1-aminoanthraquinone (I) from 5-nitro-1, 4, 4a, 9a-tetrahydroanthraquinone (II). comprises either: (a) catalytically hydrogenating compound (II) in a polar organic solvent in the presence of a hydrogenation catalyst and adding a base to the reaction system during or after completion of the hydrogenation reaction and optionally oxidizing the resultant reaction product with air or other oxidizing agent; or (b) catalytically hydrogenating compound (II) in an aqueous reaction medium in the presence of a hydrogenation catalyst and a base, and oxidizing the resultant reaction product with air or other oxidizing agent. Characteristic of the process is the fact that the hydrogen released from the tetrahydroanthraquinone nucleus (II) by the action of the base is effectively consumed for reducing the nitro group i.e. in an auto-oxidation and reduction reaction. The polar organic solvent may be chosen from e.g. #-hydroxyethyl methylether, #-hydroxydiethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether, and methoxybutanol. Palladium on carbon is a preferred hydrogenation catalyst, and air is a preferred oxidizing agent. The intermediates: 5-hydroxylamino-1, 4, 4a, 9a tetrahydroanthraquinone (Ex. 1.), 5-amino-1, 4, 4a, 9a tetrahydroanthraquinone (Ex. 2.) and 5-nitro-1, 4, 4a, 9a tetrahydroanthraquinone (Ex. 4, 13) were isolated and identified.