A 500 ml. electromagnetically stirred autoclave was charged with 10 g of 1-nitroanthraquinone having a purity of 91.5% and containing 7.0% of 1,5-dinitroanthraquinone, 0.5% of 1,8-dinitroanthroquinone and 1.0% of anthraquinone as impurities, 120 g of a 3% aqueous solution of sodium hydroxide (0.01 mole as sodium hydroxide), 80 g of methanol, and 200 mg of 5% palladium-carbon (2% based on the 1-nitroanthraquinone). The 1-nitroanthraquinone was hydrogenated at a temperature of 50° C. and a pressure of 40 to 30 Kg/cm2.G. In 60 minutes, 0.16 mole of hydrogen was absorbed, whereupon the reaction was stopped. The inside of the autoclave was purged with nitrogen, and 80 g of a 3% aqueous solution of sodium hydroxide was added. Methanol was distilled off at reduced pressure (60 to 70 mmHg abs.) and 40 to 50° C. Then, the reaction mixture was suction-filtered in a stream of nitrogen to remove the catalyst and the diaminoanthraquinones. The filtrate was oxidized with air at 20 to 30° C. for 2 hours with stirring to afford 7.65 g of 1-aminoanthraquinone having a purity of 98% in a yield of 93% of theory.
