3-AMINO-4-MERCAPTOBENZOICACID synthesis

Yield:18889-18-4 62.5%

Reaction Conditions:

Stage #1: 4-chloro-3-nitrobenzoatewith sodium sulfide in water; for 7 h;Reflux;
Stage #2: with acetic acid in water; pH=4.5 - 7.5;

Steps:

12.1

(1) 3-amino-4-mercaptobenzoic acid 100g (0.53mol) 4-chloro-3-nitrobenzoic acid was suspended in 400mL water, added as one batch to 300mL aqueous solution in which 300g (1.25mol) sodium sulfide was dissolved, the reaction liquid reacted under stirring and refluxing for 7h, cooled, neutralized with acetic acid to pH7.5, decolorized with active carbon, filtered, acidificated with acetic acid again to pH4.5, a solid was obtained by filtration, washed with water, crystallized with methanol-water to obtain a yellow solid 62.5g (62.5%), mp: 185°C(dec.).

References:

EP2354136,2011,A1 Location in patent:Page/Page column 17