Hydrogen Peroxide → 3-Bromo-2-fluorophenol

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Reaction Steps

125 ml of a 35% strength aqueous solution of hydrogen peroxide are added dropwise at room temperature to the crude 2-bromo-1-fluorophenylboronic acid (80 g) dissolved in 300 ml of tert-butyl methyl ether; during this addition, the temperature rises to 55° C. When the addition is complete, the mixture is refluxed for a further 2 hours. After the mixture has been cooled, 100 ml of water are added, and the organic phase is extracted by shaking twice with saturated sodium sulfite solution. After the solvent has been removed by distillation under reduced pressure, vacuum distillation (90° C.; 4 mbar) gives 54 g of 3-bromo-2-fluorophenol as an oil which soon crystallizes. 1H-NMR (CDCl3): 6.9-7.1 (m; 3H); 5.1 (br; 1H), 19F-NMR (CDCl3): −135 ppm.

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