535-87-5

99-34-3

535-87-5

General procedure for the synthesis of 3,5-diaminobenzoic acid from 3,5-dinitrobenzoic acid: 3,5-dinitrobenzoic acid (51 g, 0.24 mol) and 300 mL of water were added to a 1 L stainless steel high-pressure reactor and stirred thoroughly until homogeneous. Subsequently, the pH of the reaction system was adjusted to 7-8 using an aqueous sodium hydroxide solution with a mass percent concentration of 20%. 0.25 g of Ni-Yb-Al triple-acting catalyst was added followed by three nitrogen substitutions to remove air. The hydrogen pressure was controlled at 0.2 MPa and the reaction temperature was maintained at 25-30 °C until the reaction pressure decreased significantly, indicating the completion of the reaction. Upon completion of the reaction, the catalyst was recovered by filtration. The filtrate was adjusted to pH 3 with concentrated hydrochloric acid to precipitate the target product 3,5-diaminobenzoic acid. The solid product was collected by filtration, washed with water and finally dried under vacuum to give 36.5 g of 3,5-diaminobenzoic acid in 98.8% yield and 98.9% HPLC purity. The retention time of the product was consistent with the standard control.