Synthesis
General procedure for the synthesis of 3-bromo-4-iodotoluene from 2-bromo-4-methylaniline: 2-bromo-4-methylaniline (5 g, 29 mmol) was dissolved in acetonitrile (80 mL), and an aqueous hydrochloric acid solution prepared from concentrated hydrochloric acid (15 mL) and water (50 mL) was added. The reaction mixture was cooled to 0 °C and a solution of sodium nitrite (2.4 g, 34.87 mmol) in water (50 mL) was added slowly. After addition, the reaction temperature was kept below 5°C for 30 min. Subsequently, a solution of potassium iodide (7.23 g, 43.59 mmol) in water (50 mL) was added. After addition, the reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the mixture was poured into water (300 mL) and extracted with dichloromethane. The organic phases were combined and dried over anhydrous magnesium sulfate. The solvent was removed by concentration under reduced pressure to give a brown oil, which was purified by distillation to give the light yellow target product 3-bromo-4-iodotoluene.
References
[1] Tetrahedron Letters, 2012, vol. 53, # 39, p. 5248 - 5252
[2] Angewandte Chemie - International Edition, 2007, vol. 46, # 25, p. 4744 - 4747
[3] Chemistry - A European Journal, 2016, vol. 22, # 6, p. 1941 - 1943
[4] Justus Liebigs Annalen der Chemie, 1873, vol. 168, p. 153
[5] Justus Liebigs Annalen der Chemie, 1878, vol. 192, p. 202
