Hydrogen Peroxide → 3-(Difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A 3-neck 250 ml round bottomed flask was fitted with a magnetic stirrer and thermometer. Water (130 g), the product of example 1 (compound of formula IX) (6.50 g) and aqueous sodium hydroxide (8.17 g) were charged to the reactor, and the resulting solution heated to 40-45° C. A 35% hydrogen peroxide solution (39 g) was added over 1 hr, and the mixture then stirred at 40-45° C. for 0.5 hr [83% yield of desired product (compound of formula XI)−quantitative HPLC]. The pH of the reaction mass was adjusted to 2.5 by addition of 36% aqueous hydrochloric acid solution. The resulting precipitate was isolated by filtration and washed with water. Drying (60° C., 10 mbar) gave the desired product (XI) as pale yellow, free-flowing powder [69% yield of desired product−quantitative HPLC].

Provenance & Evidence