反应详情

To 400 ml of a 1N sodium hydroxide aqueous solution, was added dropwise 67.5 g of a solution (10% molar) of 3-(difluoromethyl)-5-fluoro-1-methyl-1H-pyrazole-4-carbonyl fluoride in tetrahydrothiophene 1,1-dioxide. The temperature was kept below 20° C. during the addition. After 2 hours of stirring at room temperature, the reaction mixture was carefully acidified to pH 2 with concentrated aqueous hydrochloric acid. The resulting white precipitate was filtered, washed with water, and dried to yield 6 g of 5-fluoro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid as a white solid.

1. additionThe temperature was kept below 20° C. during the addition
2. filtrationThe resulting white precipitate was filtered
3. washwashed with water
4. customdried