5071-61-4

5932-30-9

5071-61-4

General procedure for the synthesis of 5-phenyl-1H-pyrazole-3-carboxylic acid from ethyl 5-phenylpyrazole-3-carboxylate: to a solution of ethyl 5-phenylpyrazole-3-carboxylate (3.4 g, 15.9 mmol) in methanol (40 mL) was added an aqueous sodium hydroxide solution (140 mL, 4 M). The reaction mixture was stirred at room temperature for 2 hours. The reaction mixture was concentrated under reduced pressure to remove methanol. The aqueous phase was acidified to pH=3 with aqueous hydrochloric acid (1M) and extracted with ethyl acetate. The organic phase was dried with anhydrous sodium sulfate, filtered and concentrated to give the crude product. The crude product was purified by silica gel column chromatography, and the target compound 5-phenyl-1H-pyrazole-3-carboxylic acid (2.4 g, 80.4% yield) was obtained after elution. Mass spectrum (ESI) m/z: 189.1 [M+H]+.