The general procedure for synthesizing 2-fluoro-5-bromobenzotrifluoride from 2-fluorobenzotrifluoride was as follows: referring to Example 4, 400 g of concentrated sulfuric acid, 400 g of 2-fluorobenzotrifluoride, 20 g of lithium bromide, 20 g of ferric bromide, 20 g of tetrabutylammonium bromide, and 273.17 g of bromine were added to a 2000 mL three-necked flask, in sequence. The reaction temperature was controlled to be between 35-45°C. Samples were taken after 6 hours of reaction and showed 0.36% of raw material remaining by gas chromatography (GC). The reaction mixture was cooled to below 30 °C, transferred to a 2000 mL dispensing funnel and allowed to stand for 1 h to separate the acid layer. The crude product was transferred to a 2000 mL flask and 1000 g of water was added under stirring and the pH was adjusted to 7 by adding 10% sodium hydroxide solution dropwise to give 550.3 g of 2-fluoro-5-bromobenzotrifluoride crude oil in 92.84% yield. The crude oil was distilled under reduced pressure to obtain 517.18 g of pure product with a yield of 93.98% and a product purity of 95.9%.
