Potassium Carbonate → 5-(4-Fluorophenylthio)-1-methyl-3-trifluoromethylpyrazole-4-carboxylic acid

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Reaction Steps

A mixture of 5-chloro-1-methyl-3-trifluoromethylpyrazole-4-carboxylic acid (2.0 g), 4-fluorothiophenol (1.66 g) and anhydrous potassium carbonate (3.26 g) was heated under reflux in acetonitrile with stirring for 4 hours. After filtration the filtrate was evaporated, acidified with dilute hydrochloric acid and extracted with ethyl acetate. The combined extract was dried (anydrous magnesium sulphate), filtered and evaporated in vacuo. Recrystallisation from ether/hexane gave 5-(4-fluorophenylthio)-1-methyl-3-trifluoromethylpyrazole-4-carboxylic acid (0.98 g) m.p. 190°-193.7° C. as a white solid.

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