Water → 4-Chloro-3-(4-chloro-2-fluoro-5-hydroxyphenyl)-1-methyl-5-trifluoromethyl-1H-pyrazole

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Reaction Steps

1.39 g of 4-chloro-3-(4-chloro-2-fluoro-5-methoxyphenyl)-1-methyl-5-(trifluoromethyl)-1H-pyrazole was dissolved in 80 ml of anhydrous methylene chloride and then cooled with a dry ice/acetone bath and 0.14 ml of boron tribromide added. After allowing to warm to room temperature, the mixture was treated with an additional 0.28 ml of boron tribromide. Added was an additional 1.0 ml of boron tribromide and stirred at room temperature for 6 hours. After stirring, 30-50 ml of ice cooled water was added and the mixture stirred for 10 minutes. The organic phase was extracted with water, dried with anhydrous magnesium sulfate, filtered and concentrated to give 1.28 g of 4-chloro-3-(4-chloro-2-fluoro-5-hydroxyphenyl)-1-methyl-5-(trifluoromethyl)-1H-pyrazole, m.p. 123.0°-126.0° C.

Provenance & Evidence