Oxalyl chloride → 2-(2-Chloro-phenyl)-5-trifluoromethyl-2H-pyrazole-3-carbonyl chloride

Participants

Reaction Steps

A sample of crude 1-(2-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazole-5-carboxylic acid (40.8 g, 0.14 mole) was dissolved in methylene chloride (300 mL). The solution was treated with oxalyl chloride (15.7 mL, 0.18 mole), followed by N,N-dimethylformamide (12 drops). Off-gassing began shortly after adding the N,N-dimethylformamide catalyst. The reaction mixture was stirred for about 20 minutes under ambient conditions, then was heated to reflux for a period of 35 minutes. Volatiles were removed by concentrating the reaction mixture on a rotary evaporator at a bath temperature of 55° C. The crude product, approximately 43 g of a light-yellow oil, was used directly in the next step.

Provenance & Evidence