Example 4: 3.0 g (0.054 mol) of iron powder was added to 250 g (1.77 mol) of 4-fluoronitrobenzene and the mixture was heated to 140 °C. Over a period of 9 hours, 450 g (2.81 mol) of bromine was slowly added dropwise and supplemented with 15 g (0.27 mol) of iron powder in batches. After the dropwise addition was completed, stirring of the reaction mixture was continued for 6 hours. After completion of the reaction, the mixture was filtered and the filtrate was dissolved in 530 g of hot hexane. After cooling the solution, 220 g of 3-bromo-4-fluoronitrobenzene crystals precipitated in a yield of 55.8% of the theoretical value, with the product having a melting point of 55.5°C-56.5°C and a purity of 99.0%.
