Synthesis
The general procedure for the synthesis of 3-iodobiphenyl from 3-aminobiphenyl is as follows: 775 ml of concentrated hydrochloric acid is added to a 10 liter reactor. Subsequently, 775 ml of water and 775 g of ice were added and 125 g (0.740 mol) of m-aminobiphenyl was suspended therein. Under the condition of keeping the reaction temperature below 0°C, 750 ml of an aqueous solution containing 56.3 g (0.816 mol) of sodium nitrite was slowly added dropwise over a period of 30 minutes and stirring was continued at this temperature for 50 minutes. To the resulting aqueous diazonium salt solution, maintained at a temperature below 0°C, 1250 ml of an aqueous solution containing 185 g (1.12 mol) of potassium iodide was slowly added dropwise over a period of 1 hour. After the dropwise addition was completed, stirring was continued at this temperature for 1 hour, followed by stirring at room temperature for 2 hours. After completion of the reaction, the reaction mixture was extracted with ethyl acetate. The organic layer was washed with water and dried with magnesium sulfate, followed by removal of the solvent by distillation to give the crude product. Another batch of the same scale reaction was carried out. The crude products obtained from the two batches were combined and purified by silica gel column chromatography using hexane as eluent, resulting in 297 g of m-iodobiphenyl (71.7% yield for the two batches combined).
References
[1] Organic Letters, 2014, vol. 16, # 6, p. 1594 - 1597
[2] Patent: EP666298, 1995, A2
[3] Journal of the Chemical Society, 1931, p. 1111,1112
[4] Journal of the American Chemical Society, 1946, vol. 68, p. 1663
[5] Bulletin of the Chemical Society of Japan, 1975, vol. 48, p. 1868 - 1874
