Methanol → 1H-Pyrazole-3-carboxylic acid, 4-nitro-, methyl ester

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Reaction Steps

Thionyl chloride (9.2 mL) was added dropwise to a solution of 4-nitro-1H-pyrazole-3-carboxylic acid (19.77 g, 125.9 mmol) in methanol (200 mL) at 0° C. The reaction mixture was stirred at room temperature overnight, and the solvent was evaporated under reduced pressure. Water was added to the residue, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated aqueous sodium hydrogencarbonate solution and saturated brine, dried and concentrated. The obtained crude crystals were washed with diisopropyl ether to give methyl 4-nitro-1H-pyrazole-5-carboxylate (17.8 g, 82%).

Provenance & Evidence