To an aqueous sodium hydroxide solution (400 ml) of 4-bromo-2,3-difluorophenol (T-1) (195.0 g), ethidium bromide (196.2 g), and tetrabutylammonium bromide (TBAB) (24.2 g) was added sodium hydroxide (75.9 g), and the reaction was heated and stirred under nitrogen protection for 6 hr at 80 °C. After completion of the reaction, extraction was carried out with heptane and the organic layer was washed sequentially with water and saturated saline. Subsequently, the organic layer was dried with anhydrous magnesium sulfate and concentrated under reduced pressure to give a black oily substance. The oily substance was purified by distillation to give 1-ethoxy-2,3-difluorobromobenzene (T-2) as a colorless oily liquid (230.0 g, yield: 97%).
