Preparation of novel ionic liquids and their applications in brominating reaction

Abstract

Novel acidic ionic liquids, 1-(ω-sulfonicacid)propyl-3- methylimidazolium bromide ([HSO3pmim]Br)and 1-(ω-sulfonicacid)butyl-3- methylimidazolium bromide ([HSO3bmim]Br), were prepared and used as brominating agents, catalysts and solvents in the synthesis of 1,7-dibromoheptane, respectively. 1,7-dibromoheptan with a yield of 95% was obtained at 100 °C for 2 h by simple phase separation. The acidic ionic liquid [HSO3pmim]Br was recycled for 5 times and the yield of 1,7-dibromoheptane did not decrease remarkably, which indicates that catalysts still maintain good selectivity and activity after recycling. The structure of the acidic ionic liquid [HSO3pmim]Br was characterized with IR, and it was found that [HSO3pmim]Br had stronger acidity than other ionic liquid.