3-Chlorobenzenesulphonyl chloride → Sodium 3-chlorobenzene-1-sulfinate

A solution of sodium sulphite (627 mg, 4.98 mmol) and sodium bicarbonate (418 mg, 4.98 mmol) in water (13 mL) was stirred vigorously with 3-chlorobenzenesulfonyl chloride (500 mg, 2.36 mmol) at 0° C. for 30 min then heated at 65° C. for 3 h. After cooling to ambient temperature, the reaction mixture was washed with dichloromethane (2×20 mL) and lyophilized. The resulting white solid was stirred with methanol (10 mL) for 5 min and the insoluble inorganic salts removed by filtration. The filtrate was concentrated in vacuo to approximately 3 mL and an equal volume of diethyl ether added. The precipitated solid containing residual inorganic salts was filtered and set aside. The remaining filtrate was diluted with excess diethyl ether, filtered and the filtered solid dried in vacuo to give sodium 3-chloro-benzenesulfinate (306 mg, 65%) as a white solid: 1H NMR (DMSO-d6, 300 MHz) δ 7.43 (br s, 1H), 7.35-7.39 (m, 1H), 7.32 (d, J=7.2 Hz, 1H), 7.26 (dt, J=7.5, 1.8 Hz, 1H).