Phosphorus pentachloride → HCID 131713672, compound

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Reaction Steps

The above acid (22 g, 0.11 mol) is added in portions at 70°-90° C. to a stirred acid mixture prepared by adding 30 ml conc. sulfuric acid to 15 ml of 90% nitric acid. After stirring two hours at 95°, the mixture is poured into 75 g of ice. The collected precipitate is dried to give 23 g, 1-(2,2,2-trifluoroethyl)-3-methyl-4-nitropyrazole-5-carboxylic acid, mp 135°-138° C. This nitro acid (23 g, 0.09 mol) is mixed with 21 g (0.1 mol) of phosphorus pentachloride and heated on a steam bath for 2.5 hr, filtered, and evaporated in vacuo to give 20 g of 1-(2,2,2-trifluoroethyl-3-methyl-4-nitropyrazole-5-carbonyl chloride as an oil. The acid chloride (20 g) in 30 ml of acetone is added dropwise to 130 ml cold concentrated ammonium hydroxide and the mixture is filtered after stirring one hour to give 16 g of 3-methyl-4-nitro-1-(2,2,2-trifluoroethyl)-5-pyrazolecarboxamide, mp 205°-207° C. from ethyl acetate.

Provenance & Evidence