Water → 3-(5-Nitrofuran-2-yl)-1-phenyl-1H-pyrazole-4-carboxylic acid

Participants

Reaction Steps

Add 36 g of 98% nitrosylsulfuric acid (under cooling with ice) dropwise to a suspension of 50 g 3-(5-nitro-2-furyl)-1-phenylpyrazole-4-carboxamide in 830 ml of 89% orthophosphoric acid, whereupon the temperature rises from 0° C to 35° C. Stir the resulting reaction mixture for 18 hours at room temperature and pour the produced solution onto 5 kg of ice and water. Separate the formed precipitate and wash it with water until it is no longer acid to obtain a 98% yield of 3-(5-nitro-2-furyl)-1-phenylpyrazole-4-carboxylic acid [m.p. 264° to 265.5° C (with decomposition) from dioxane].

Provenance & Evidence