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2-Chloro-4-sulfamoylanilide is an organic compound commonly used as a synthetic intermediate, especially in the synthesis of pharmaceuticals, pesticides and dyes.

The general procedure for the synthesis of 4-amino-3-chlorobenzenesulfonamide from crystalline sulfonamide was as follows: 1 mmol of sulfonamide was dissolved in 12 mL of tetrahydrofuran under anhydrous and anaerobic conditions. Subsequently, 2 mmol of N-chlorosuccinimide (NCS) powder was added, and the reaction mixture was stirred at 40 °C for 25 hours. After completion of the reaction, the solvent was evaporated by rotary evaporator. The residue was extracted with 30 mL of ethyl acetate. The organic layer was washed sequentially with 5 mL of saturated potassium carbonate solution and 5 mL of saturated sodium chloride solution. The washed organic layer was dried with anhydrous sodium sulfate, filtered and purified by column chromatography (eluent ratio of dichloromethane: ethyl acetate = 7:1). Finally, 188 mg of the light yellow powdery product 4-amino-3-chlorobenzenesulfonamide was obtained in 95% yield.

[1] Patent: CN107400060, 2017, A. Location in patent: Paragraph 0011; 0029; 0030; 0036; 0037; 0043-0044; 0050-0051
[2] Indian Journal of Chemistry, Section A: Inorganic, Physical, Theoretical & Analytical, 1988, vol. 27, # 12, p. 1028 - 1030