Thionyl Chloride → 1-(Chloromethyl)-1H-benzotriazole

Participants

Reaction Steps

1-Chloromethyl benzotriazole was prepared using the procedure outlined in JACS 74, 3869 (1952). Solid 1-hydroxymethyl benzotriazole (45.0 parts) was stirred mechanically and thionyl chloride (130 parts) was added dropwise at a fairly rapid rate so that the slurry could be agitated while immersed in an ice bath. A nitrogen sweep was employed so that the gasses evolved could be bubbled through a dilute sodium hydroxide solution. After all of the thionyl chloride had been added, the mixture was allowed to warm to room temperature. The mixture was heated to 40° C. and gas evolution became vigorous and the caked-up solid dissolved to yield a clear, pale yellow solution. The mixture was warmed to 65° C. where it was held for 60 minutes. Excess thionyl chloride was distilled off slowly and when distillation ceased, the mixture was cooled to 35°-40° C. and 100 parts of methanol was added to scavenge any residual thionyl chloride. The solution was warmed to reflux and the precipitated solid was broken up with a stirring rod. After 15 minutes at reflux the solution was cooled in an ice bath for 30 minutes and the pale brown solid was filtered and dried in a vacuum oven. The yield of 1-chloromethyl benzotriazole was 41.6 parts (82.9% yield), m.p. 137°-139° C., literature 136°-8° C.

Provenance & Evidence