Ammonia → 3,5-Dichloro-2-hydroxybenzenesulfonamide

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Reaction Steps

A solution of 26.1 gm (0.1 mole) 3,5-dichloro-2-hydroxybenzenesulfonyl chloride in 400 ml dry tetrahydrofuran was cooled to 0° with an ice bath, and 11 ml (0.5 mole) anhydrous ammonia was added dropwise, with stirring. The rate of addition was sufficiently slow so as to keep the temperature of the reaction medium less than 10°. The mixture was stirred for 1.5 hours at 0° then slowly warmed to room temperature. The solvent was removed in vacuo and the residue was treated with 100 ml H2O. A small amount of insoluble by-product was filtered off and then the aqueous solution was acidified to pH=2.0 with 1 N HCl solution. Filtration of the resulting white precipitate and drying of the precipitate at 50° under vacuum gave 23.6 gm (97%) white solid, m.p. >225°. The infrared spectrum showed strong absorption at 3300, 1540, 1450 and 1320 cm-1, and the nuclear magnetic resonance spectrum showed a broad singlet at 7.2δ, 3 protons, and a doublet of doublets at 7.8δ, 2 protons. These data are consistent with the desired product.

Provenance & Evidence