Reaction #792176

Reaction equation

sodium hydroxide

Water

ethyl 1-(3-chloro-2-pyridinyl)-3-(2,2,2-trifluoroethoxy)-1H-pyrazole-5-carboxylate

water

→

title compound

1-(3-Chloro-2-pyridinyl)-3-(2,2,2-trifluoroethoxy)-1H-pyrazole-5-carboxylic acid

Solvents

methanol

Conditions

Workup

1. 1
   Extractionthe reaction mixture was extracted with ethyl ether, which
2. 2
   Extractionextracted with ethyl acetate (50 mL)
3. 3
   ExtractionThe ethyl acetate extract
4. 4
   Washwhich was washed with water (20 mL) and brine (20 mL)
5. 5
   Dryingdried over magnesium sulfate
6. 6
   Concentrationconcentrated

Procedure

To a stirred solution of ethyl 1-(3-chloro-2-pyridinyl)-3-(2,2,2-trifluoroethoxy)-1H-pyrazole-5-carboxylate (i.e. product of Step B) (0.92 g, 2.8 mmol) in methanol (15 mL) was added water (5 mL), which caused the reaction mixture to become cloudy. An aqueous solution of sodium hydroxide (50%, 1.5 g, 19.2 mmol) was added dropwise, and the reaction mixture was stirred at room temperature for 30 minutes, during which time the reaction mixture became again clear. Water (20 mL) was added and the reaction mixture was extracted with ethyl ether, which was discarded. The aqueous phase was acidified to pH 2 using concentrated hydrochloric acid and then extracted with ethyl acetate (50 mL). The ethyl acetate extract, which was washed with water (20 mL) and brine (20 mL), dried over magnesium sulfate and concentrated to give the title compound, isolated as a white solid (0.8 g).

Source