Hydrochloric Acid → 1-Ethyl-3-(pentafluoroethyl)-4-(trifluoromethyl)-1H-pyrazole-5-carboxylic acid

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Reaction Steps

0.23 g (0.72 mmol) of methyl 3-(pentafluoroethyl)-4-(trifluoromethyl)-1H-pyrazole-5-carboxylate and 0.3 g (2.2 mmol) of potassium carbonate are suspended in 7.0 ml of acetone and admixed with 0.12 ml of iodoethane (1.4 mmol). The reaction mixture is stirred overnight at room temperature. 1.1 ml (2.2 mmol) of 2N sodium hydroxide solution are added to the suspension. The solution is then stirred overnight at room temperature. The reaction mixture is diluted with water and adjusted to pH 2-3 with 1M hydrochloric acid. The aqueous reaction solution is extracted three times with ethyl acetate. The combined organic phases are dried over magnesium sulphate, filtered and concentrated by evaporation under reduced pressure on a rotary evaporator. This gives 0.22 g of 1-ethyl-3-(pentafluoroethyl)-4-(trifluoromethyl)-1H-pyrazole-5-carboxylic acid (91%) as a colourless solid.

Provenance & Evidence