636-76-0

4025-64-3

636-76-0

General procedure for the synthesis of 3-sulfobenzoic acid from 3-chlorosulfonylbenzoic acid: 25 g of 3-(chlorosulfonyl)benzoic acid (commercially available, Aldrich) was added in batches to 250 mL of 25% ammonium hydroxide solution under ice bath conditions. The reaction mixture was stirred at room temperature for 15 hours. Upon completion of the reaction, the solvent was concentrated by distillation under reduced pressure to about 50 mL. Subsequently, the mixture was acidified with concentrated hydrochloric acid to pH < 2. The precipitated white solid was collected by filtration and dried with a vacuum desiccator to afford 22 g (96% yield) of 3-sulfobenzoic acid. The product was characterized as follows: 1H NMR (DMSO-d6) δ 13.44 (br s, 1H), 8.38 (s, 1H), 8.14 (d, J = 7.5 Hz, 1H), 8.04 (d, J = 7.9 Hz, 1H), 7.72 (t, J = 7.9 Hz, 1H), 7.49 (s, 2H); HPLC (max plot) 97%; Rt 0.68 min; LC/MS (ES-): 199.8.