5-Phenyl-1H-pyrazole-3-carboxylic acid

56426-35-8

1134-49-2

To a mixed solution of methyl 5-phenylpyrazole-3-carboxylate (6.02 g, 29.8 mmol) in THF with H2O (3:1, 140 mL) was added LiOH (3.42 g, 142.8 mmol) and the reaction mixture was stirred overnight at room temperature. After completion of the reaction, the mixture was poured into 2N HCl solution (150 mL) and extracted with ethyl acetate. The organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give 3-phenyl-1H-pyrazole-5-carboxylic acid (3.2 g, 57.1% yield). The product was confirmed by mass spectrometry (EI) with molecular formula C10H8N2O2, m/z: 189.26 (MH+).