[Cl:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([Cl:8])[C:3]=1[OH:9].[Br:10]Br.S([O-])([O-])=O.[Na+].[Na+]>C(#N)C>[Br:10][C:6]1[CH:7]=[C:2]([Cl:1])[C:3]([OH:9])=[C:4]([Cl:8])[CH:5]=1A stirred solution of 2,6-dichlorophenol (20 g, 123.4 mmol) in acetonitrile (200 mL) was cooled to 0° C. and bromine (23.7 g) in acetonitrile (50 mL) was added dropwise. The red solution was stirred at 0° C. for 2 h and a saturated aqueous solution of sodium sulphite was added until the red color disappeared. The phases were separated and the aqueous phase was extracted three times with ethyl acetate. Concentration of the combined organic phases gave a yellow oil, which was purified on a silica gel column (heptane/ethyl acetate, 10:1) to give 17.8 g of 4-bromo-2,6-dichlorophenol as a white solid. Yield: 60%; 1H NMR (400 MHz, CDCl3): δ 7.42 (s, 2H), 5.9 (br s, 1H) ppm.
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