25g (132.3mmol, 1.0eq) of 2-fluoro-4-bromotoluene, 521mg (3.2mmol, 0.024eq) of AIBN, 1.6g (6.5mmol, 0.049eq) of Co(OAc)2·4H2O, and 449mg (4.4mmol, 0.033eq) of NaBr were dissolved in 250mL (10V) of HOAc. The mixture was stirred until completely dissolved and set aside. The temperature of the external bath of the reaction coil was raised to 130℃, and the pressure of the coil was adjusted to 1.2MPa with oxygen. Then the feed was started. The residence time of the system was 1.5h, and the oxygen content was 3-5eq.
The system was directly pumped into 375 mL of purified water. The pH of the system was adjusted to 12–14 with NaOH solid. The aqueous phase was extracted twice with 125 mL MTBE. The pH of the aqueous phase was then adjusted to 1 with concentrated HCl, resulting in the precipitation of a large amount of solid. Filtration yielded 25.5 g of the target product, with a yield of 88%. ¹H-NMR (CDCl₃) δ: 7.38–7.42 (m, 2H), 7.89 (t, 1H, J = 7.88).
