m-Chloroperbenzoic acid → 2-(1-Chloro-2,2,2-trifluoroethyl)-2-(trifluoromethyl)-5-hydroxy-1,3-benzodioxole

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Reaction Steps

50 g of 2(1-chloro-2,2,2-trifluoroethyl)-2-(trifluoromethyl)-5-formyl-1,3-benzodioxole were dissolved in 500 ml of methylene chloride, and 53 g of 70% by weight m-chloroperbenzoic acid were added. The reaction mixture was stirred under reflux for 6 hours. It was then cooled and the precipitate formed was filtered off. The filtrate was washed with 5% by weight aqueous sodium hydrogen-sulphite solution and saturated aqueous sodium hydrogen-carbonate solution and concentrated on a rotary evaporator. The remaining residue was dissolved in 300 ml of diethyl ether, and 100 ml of 1 N sodium hydroxide solution were added at room temperature. When the reaction was complete, the phases were separated and the organic phase was washed with saturated aqueous ammonium chloride solution, dried over magnesium sulphate and subjected to fractional distillation under vacuum. The yield was 26 g (=54% of theory) and the boiling point was 95° C. at 0.07 mbar. 19F NMR: -68.6 and -81.6 ppm. 1H NMR: 4.70 ppm.

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