4-Chlorobenzenesulfonyl chloride → 2-{[(4-Chlorophenyl)sulfonyl]amino}-4,5-dimethoxybenzoic acid

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Reaction Conditions

Reaction Steps

33.71 g (0.32 mol) of sodium carbonate were dissolved in 250 ml of water and heated to 60° C. 25.00 g (0.13 mol) of 2-amino-4,5-dimethoxybenzoic acid were introduced into the solution, and 29.55 g (0.14 mol) of 4-chlorobenzenesulfonyl chloride were added in portions to this solution over the course of 15 min. After the mixture had been cooled, the residue was filtered off with suction and taken up in 1% strength sodium bicarbonate solution and, after filtration, the product was precipitated by adding 1 N hydrochloric acid. 25.90 g (55%) of 2-(4-chlorophenylsulfonylamino)-4,5-dimethoxybenzoic acid of melting point 212-214° C. were obtained. 25.90 g (0.07 mol) of 2-(4-chlorophenylsulfonylamino)-4,5-dimethoxybenzoic acid were suspended in 75 ml of toluene and, after addition of 17.30 g (0.08 mol) of phosphorus pentachloride, the mixture was stirred at 40-45° C. for 2.5 h. It was then concentrated to half the volume in vacuo, and the precipitated product was filtered off with suction and washed with a little toluene. 25.30 g (93%) of 2-(4-chlorophenylsulfonylamino)-4,5-dimethoxybenzoyl chloride, of melting point 175-177° C., were obtained.

Provenance & Evidence