反应详情

N-Methyl-3-difluoromethyl-5-trifluoromethyl-4-pyrazolecarboxylic acid ethyl ester (0.5 g, 1.84 mmol) in ethanol (3 ml) was admixed gradually with an 8N aqueous sodium hydroxide solution (0.7 ml) and stirred at room temperature for 3 h. The solvent was removed by rotary evaporation; the residue was taken up in water (10 ml) and extracted with diethyl ether (10 ml). Acidification to pH 1 with 1M HCl was followed by extraction with ethyl acetate (3×10 ml). The combined organic phases were dried over sodium sulphate and filtered, and the solvent was removed by rotary evaporation. N-Methyl-3-difluoromethyl-5-trifluoromethyl-4-pyrazolecarboxylic acid (0.44 g, 1.80 mmol, 98%) was isolated as a yellowish solid.

1. customThe solvent was removed by rotary evaporation
2. extractionextracted with diethyl ether (10 ml)
3. extractionAcidification to pH 1 with 1M HCl was followed by extraction with ethyl acetate (3×10 ml)
4. dry with materialThe combined organic phases were dried over sodium sulphate
5. filtrationfiltered
6. customthe solvent was removed by rotary evaporation