Hydrogen Bromide → 3-Bromo-5-iodophenol

1-Bromo-3-iodo-5-methoxy-benzene (6.29 g, 20.1 mmol) was suspended in a solution of hydrogen bromide in acetic acid (33%, 150 mL). Tetrabutylammonium bromide (0.5 g, 1.55 mmol) was added and the mixture was heated to reflux under vigorous stirring for 2 d. After cooling to room temperature the mixture was extracted with methylene chloride (3×100 mL). The combined organic layers were washed with water (50 mL), dried (MgSO4) and concentrated to give the crude product which was purified by flash chromatography on silica gel (300 g, AcOEt/heptane 1:9). 3-Bromo-5-iodo-phenol (21.2 g, 96%) was obtained as pale brown solid.