METHOD FOR PRODUCING AMINOBENZOIC ACIDS Russian patent published in 1998 - IPC

FIELD: organic chemistry; production of ortho-, metha- and para-aminobenzoic acids for use as intermediates for synthesis of pharmaceuticals, dyes, antioxidants, developers and other chemicals. SUBSTANCE: aminobenzoic acids are produced by liquid-phase hydrogenation of corresponding precursor nitrobenzoic acids or their alkali salts, in presence of support-borne palladium-containing catalysts, namely: palladium-modified and iron-containing nickel catalyst, or iron-containing palladium catalyst. Nickel catalyst contains 0.07-0.25% and 0.05-0.3% of iron based on weight of support, nickel-to-palladium weight ratio in catalyst is 1:1-0.5. Palladium catalyst contains 0.07-0.6% of palladium and 0,05-0.55% of iron based on weight support. Palladium is applied onto support by adsorption from aqueous solutions of palladium chlorohydroxy complex compounds prepared with alkali metal hydroxide-to-palladium weight ratio of 0.25-0.65:1. High-purity aminobenzoic acids are produced with yield 85-95% of theoretical. EFFECT: higher process output. 4 cl