Hydrochloric Acid → 5-oxo-1-phenyl-2,5-dihydro-1H-pyrazole-3-carboxylic acid

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Reaction Steps

Methyl 5-oxo-1-phenyl-2,5-dihydro-1H-pyrazole-3-carboxylate (0.35 g; 1.60 mmol) in 5 ml of 2M NaOH solution was heated at 60° C. for 2 h after which the reaction mixture was made acidic with 1.5 ml of concentrated HCl which caused the product to form a yellow precipitate. Filtering gave 0.18 g of the product. 1H-NMR (400 MHz; d6-DMSO): δ 5.97 (s, 1H), 7.33-7.37 (m, 1H), 7.48-7.52 (m, 2H), 7.74 (m, 2H).

Provenance & Evidence