Study of synthesis of local anesthetics para aminobenzoic acid

Amino acid was synthesized by reduction technology with the nitro benzoic acid and sodium sulfide as raw material. After heating,cooling,filtering,heavy crystallization steps,the products were characterized by melting point measurement method. The dosage of reductant,dissolve of dosage,reaction time,reaction temperature,crystallization solution pH value were investigated on its yield.The results show that: When the p-nitrobenzoic acid and molar ratio of sodium sulfide was 1∶2.0,the p-nitrobenzoic acid and molar ratio of sodium bicarbonate was 1∶3.0,reaction temperature 60℃,reaction time 60min,the crystallization solution pH=5,yield of the amino acid was higher.