Hydrogen Peroxide → 5-Chloro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

In a 500 ml flask, 6.0 g (31 mmol) of 5-chloro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carbaldehyde were added to 30 ml of toluene. A solution of 2.4 g (62 mmol) of sodium hydroxide in 6 ml of water was added to the reaction mixture, followed by 103 ml of a 30% solution of hydrogen peroxide in water, whilst keeping the temperature below 37° C. After the end of the addition, the reaction mixture was stirred at 50° C. for 7 hours. Once the reaction mixture was back to room temperature, the two phases were separated and the organic phase was extracted with 100 ml of water. The combined aqueous phases were acidified to pH 2 with aqueous hydrochloric acid. The resulting white precipitate was filtered, washed with 2*20 ml of water, and dried to yield 3.2 g of 5-chloro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid as a white solid.

Provenance & Evidence