Hydrochloric Acid → 4-Bromo-2-chlorobenzenesulfonyl chloride

Participants

Reaction Steps

A stirred solution of 4-bromo-2-chloroaniline (3.99 g) in acetic acid (90 ml) at 15° C. is treated with concentrated hydrochloric acid (22 ml), followed by a solution of sodium nitrite (1.29 g) in water (4.5 ml) at 10° C. After 30 min, the mixture is added to a stirred solution of sulfur dioxide (32 g) and copper II chloride (1.3 g) in acetic acid (128 ml) and water (6.4 ml), also at 10° C. After stirring for a further 16 hours, the mixture is diluted with ice-cold water (500 ml) and extracted with ethyl acetate (4×100 ml). The combined extracts are washed successively with water (4×100 ml) and then brine, dried over magnesium sulfate, filtered and evaporated to give crude 2-chloro-4-bromobenzenesulfonyl chloride.

Provenance & Evidence