Ethanol → 1-(4-Methylphenyl)-3-oxo-2,3-dihydro-1H-pyrazole-4-carboxylic acid

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Reaction Steps

The ester prepared in (b) above (245 mg, 0.99 mmol) in 2.5N sodium hydroxide (5 ml) and ethanol (1 ml) was stirred at reflux under nitrogen for 0.75 hours. and then allowed to cool. The solution was washed with ethylacetate and then acidified to pH 1.5 (5 N HCl), whereupon the title compound precipitated out, was filtered and was washed with water. Drying in vacuum gave (183 mg). νmax (Nujol) 1655, 1580, 1525, 1325, 1140, 100, cm-1. δ(CD3OD+Drop D6DMSO) 2.38 (3H,s, p-CH3), 7.50 (4H, ABq, J9 Hz, aryl protons) 8.55 (1H,s,C3 pyrazole proton). Found:M+, 2.8.0696; C11H10N2O3 requires M,218.0691.

Provenance & Evidence