Water → 1-(4-Chlorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylic acid

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Reaction Steps

Part C: To a stirred suspension of ethyl 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylate (23.0 gram, 0.07 mol) in methanol (200 ml) is added water (15 ml) and concentrated NaOH (10 ml) and the resulting solution is heated at reflux temperature for 2 hours. The methanol is partly removed by evaporation and the residue is dissolved in a mixture of water and ethyl acetate. Ice, concentrated HCl (20 ml) and ethyl acetate are successively added, the ethyl acetate layer collected, dried over MgSO4, filtered and concentrated in vacuo. The resulting residue is washed with diethyl ether (100 ml) and diisopropyl ether respectively, to give 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylic acid (16.46 gram, 78% yield). Melting point: 177-179° C.

Provenance & Evidence