Sodium Hydroxide → N-tert-Butyl-3,5-di(difluoromethyl)-4-pyrazolecarboxylic acid
Reaction equation
C([O:3][C:4]([C:6]1[C:7]([CH:18]([F:20])[F:19])=[N:8][N:9]([C:14]([CH3:17])([CH3:16])[CH3:15])[C:10]=1[CH:11]([F:13])[F:12])=[O:5])C.[OH-].[Na+]>C(O)C>[C:14]([N:9]1[C:10]([CH:11]([F:12])[F:13])=[C:6]([C:4]([OH:5])=[O:3])[C:7]([CH:18]([F:20])[F:19])=[N:8]1)([CH3:17])([CH3:15])[CH3:16]Participants
4
Procedure
N-tert-Butyl-3,5-di(difluoromethyl)-4-pyrazolecarboxylic acid ethyl ester (3.40 g, 11.5 mmol) in ethanol (23 ml) was admixed gradually with an 8N aqueous sodium hydroxide solution (4.3 ml) and stirred at room temperature for 3 h. The solvent was removed by rotary evaporation; the residue was taken up in water (40 ml) and extracted with diethyl ether (20 ml). Acidification to pH 1 with 6M HCl was followed by extraction with ethyl acetate (3×30 ml). The combined organic phases were dried over sodium sulphate and filtered, and the solvent was removed by rotary evaporation. N-tert-Butyl-3,5-di(difluoromethyl)-4-pyrazolecarboxylic acid (3.0 g, 11.2 mmol, 97%) was isolated as a pale reddish solid.