A polymer imidazole salt as phase-transfer catalyst in halex fluorination irradiated by microwave

A new imidazole polymer salt was synthesized in order to develop a high efficiency phase-transfer catalyst for multi-phase reactions. The polymer salt was prepared easily by co-polymerization of 1-1′-(1,4-butamethylene)bis(imidazole) and 1,2-dibromoethane, and has the properties of excellent chemical and thermal stability and high ionic conductivity. It was applied as phase-transfer catalyst in the fluorination of chloronitrobenzenes under the irradiation of microwave and gave excellent yields of corresponding fluoronitrobenzenes. In addition, the enhanced mechanism of microwave was studied and found “non-thermal” effect was a great factor.

Graphical abstractA new imidazole polymer salt was synthesized in order to develop a high efficiency phase-transfer catalyst for multi-phase reactions. The polymer salt was prepared easily by co-polymerization of 1-1′-(1,4-butamethylene)bis(imidazole) and 1,2-dibromoethane, and has the properties of excellent chemical and thermal stability and high ionic conductivity. It was applied as phase-transfer catalyst in the fluorination of chloronitrobenzene derivatives under the irradiation of microwave and gave excellent yields of corresponding fluoronitrobenzene derivatives. The yields of products under the optimum reaction conditions were in the range of 70.2–94.2%, and the reaction time can be shortened more or less when compared with conventional heating. The catalytic effect is better than other kind of polymer phase transfer catalysts. In addition, “non-thermal effect” of microwave was found in fluorination through comparing macroscopic kinetics between conventional heating and microwave heating.Figure optionsDownload full-size imageDownload as PowerPoint slide