Hydrochloric Acid → 2,3-Dichlorobenzene-1-sulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 70.0 g of 2,3-dichloroaniline in 51 mL of acetic acid was added 180 mL of concentrated hydrochloric acid portionwise. External cooling was used to maintain the temperature below 50° C. To this thick mixture at -5° C. was added a solution of 37.0 g of sodium nitrite in 80 mL of water dropwise at a rate that maintained the temperature below 50° C. After the addition was complete, the cloudy mixture was stirred at 0° C. for 10 minutes, and was then poured slowly into a suspension of 500 mL of acetic acid, 150 mL of sulfur dioxide and 10 g of cupric chloride dihydrate at 10°-20° C. Moderate gas evolution with excessive foaming occurred, but subsided after approximately ten minutes. This light brown mixture was stirred at ambient temperature for 1-1.5 hours and was then poured into 2 L of ice water with stirring. The resultant light brown precipitate was filtered, washed twice with 200 mL portions of water, and dried to yield 110 g of 2,3-dichlorobenzenesulfonyl chloride as a light brown solid, m.p. 56°-58° C., which was used without further purification; IR (nujol): 1375, 1175 cm-1.

Provenance & Evidence