Reaction #792151

Reaction equation

N,N-dimethylformamide

1-phenyl-3-(trifluoromethyl)pyrazole-5-carboxylic acid

product

1-Phenyl-3-(trifluoromethyl)-1H-pyrazole-5-carboxylic acid

oxalyl chloride

→

1-Phenyl-3-(trifluoromethyl)-1H-pyrazole-5-carbonyl chloride

Solvents

methylene chloride

Conditions

Workup

1. 1
   Temperaturewas heated
2. 2
   Temperatureto reflux for a period of 35 minutes
3. 3
   OtherVolatiles were removed
4. 4
   Otheron a rotary evaporator at a bath temperature of 55° C

Procedure

A sample of crude 1-phenyl-3-(trifluoromethyl)pyrazole-5-carboxylic acid (i.e. the product of Step B) (4.13 g, 16.1 mmol) was dissolved in methylene chloride (45 mL). The solution was treated with oxalyl chloride (1.80 mL, 20.6 mmol), followed by N,N-dimethylformamide (0.010 mL, 0.13 mmol). Off-gassing began shortly after adding the N,N-dimethylformamide catalyst. The reaction mixture was stirred for ˜20 minutes under ambient conditions, then was heated to reflux for a period of 35 minutes. Volatiles were removed by stripping the reaction mixture on a rotary evaporator at a bath temperature of 55° C. The product consisted of 4.43 g of a light-yellow oil. The only impurity observed by 1H NMR was N,N-dimethylformamide.

Source