In a 5L four-necked flask, add 210g of 3-acetyl-5-chloro-2-(benzylmercapto)thiophene and 1500g of acetonitrile, stir, add 320g of glacial acetic acid and 200g of water, control the temperature between 0-15℃, add 241.6g of trichloroisocyanuric acid in batches, complete the addition in about 30min, keep the reaction at 0-15℃, and monitor the reaction by TLC until the starting material disappears. The solvent was removed by concentration under reduced pressure in a water bath at 35–45°C. 1500 g of a 25% ethyl acetate-petroleum ether solution was added, stirred, filtered, and the filtrate was evaporated to dryness under reduced pressure to obtain 182.7 g of a pale yellow oily substance, which was 3-acetyl-5-chloro-2-thiophene sulfonyl chloride. The sulfonyl chloride was diluted with 105 g of ethyl acetate, and the solution was added dropwise to 420 g of ammonia water while maintaining the temperature at 0–15°C. The mixture was stirred until the sulfonyl chloride disappeared, then cooled to approximately 0°C and stirred to allow crystals to precipitate for 1 hour. The solution was filtered, washed with a small amount of water, and the resulting solid was dried at 40°C to obtain 162.4 g of a white, near-white 3-acetyl-5-chlorothiophene-2-sulfonamide, with a yield of 91.2%. The HPLC purity was greater than 99%.
