Hydrochloric Acid → 3-Amino-5-nitro-4-phenylbenzoic acid

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Reaction Steps

To a stirred solution of 3,5-dinitro-4-phenylbenzoic acid (135 g) in a mixture of pyridine (625 ml) and water (625 ml), sodium dithionite (235 g) is added in portions during about 30 minutes, keeping the temperature at 12°-15° C by external cooling. After additional stirring at this temperature for about 15 minutes, the resulting solution is acidified by the addition of conc. hydrochloric acid (750 ml), keeping the temperature below 25° C by the addition of ice to the reaction mixture. The mixture is left for about 20 hours, and the resulting precipitate is then collected by filtration, washed with water and dried. After recrystallization from aqueous ethanol, 3-amino-5-nitro-4-phenylbenzoic acid is obtained with a melting point of 247°-249° C (dec.).

Provenance & Evidence