The general procedure for synthesizing 3-bromoethylbenzene from 3-ethylaniline is as follows:Reference Example 1 Synthesis of 1-bromo-3-ethylbenzene. To a 50% aqueous sulfuric acid solution (43.6 g) containing 3-ethylaniline (10.0 g, 82.5 mmol), an aqueous sodium nitrite solution (16.5 mL containing 6.83 g, 99.0 mmol) was slowly added dropwise at 0°C, and the dropwise process lasted for 30 minutes. The resulting reaction mixture was continued to be stirred at 0°C for 45 min. Subsequently, the prepared diazonium salt solution was added in batches to a 48% hydrobromic acid solution (82.5 mL) containing copper(I) bromide (12.4 g, 86.6 mmol) while maintaining a mild reflux condition. After addition, the reaction mixture was heated to reflux for 30 minutes. Upon completion of the reaction, the mixture was cooled to room temperature and extracted with ether. The extract was washed sequentially with 1N aqueous sodium hydroxide and saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product obtained was purified by silica gel column chromatography (eluent: hexane/ethyl acetate=20:1) to give 3-bromoethylbenzene (6.13 g, 40% yield) as an oil.1H-NMR (CDCl3) δ: 1.23 (3H, t, J=7.5 Hz), 2.63 (2H, q, J=7.5 Hz), 7.11-7.20 (2H, m). 7.28-7.38 (2H, m).
