Benzoic Acid → Benzoic acid, 3-(chlorosulfonyl)-

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Reaction Conditions

Reaction Steps

Benzoic acid (250 g, 2.05 mol) was placed in a 1-L round-bottom flask, and chlorosulfonic acid (1 L, 1760 g, 15.1 mol) was added. The mixture was heated with stirring at 120-125° C. for 2 h, allowed to cool to 40-50° C., and added dropwise to an excess of crushed ice. The precipitated product was collected by filtration and dissolved in 1 L of ethyl acetate; then the aqueous layer that formed was separated, and the organic layer was washed with 100 mL of water, dried over sodium sulfate, and concentrated by evaporation to near dryness. After trituration with 300 mL of hexane, the product was collected by filtration, washed on the filter with 200 mL of hexane, and dried in air to give 384.1 g (85%) of 3-chlorosulfonylbenzoic acid, mp 134-135° C. (lit. mp 134-135° C.); 1H NMR (400 MHz, in CDCl3 w/TMS, ppm) 11.43 (broad s, CO2H), 7.81 (t, J=8.0 Hz, H-5), 8.32 and 8.50 (2d, J=8.0 Hz, H-4 and H-6), 8.79 (t, J=1.6 Hz, H-2); {1H}13C NMR (100 MHz, in CDCl3 w/TMS, ppm) 170.00 (C═O), 145.06 (C-3), 136.71 (C-6), 131.92 (C-4), 131.31 (C-1), 130.63 (C-5), 128.91 (C-2). Preparation of 3-Mercaptobenzoic Acid

Provenance & Evidence