Reaction kinetics of [BPy] Br and [BMIm] Br under microwave-assisted synthesis

N-methyl imidazole bromide([BPy]Br) and 1-methyl-3-butyl imidazole bromide([BMIm]Br) were synthesized by the respective reactions of pyridine and N-methyl imidazole under microwave radiation in a microwave reactor.Reaction kinetics was determined by AgNO3 titration to obtain the reaction kinetics equation,and the influences of reactants,temperature,and solvent were also investigated.The mechanism of microwave-assisted reactions was proposed.Results showed that the reaction abides by SN2 mechanism,and the global reaction was of the second order.The reaction rate constant was enlarged by 10 times compared to traditional heating methods,and increased with rising temperaturing.The rate constant for synthesis of [BPy]Br in isopropanol was about 5 times larger than in n-heptane.The activation energy was 30.39kJ/mol for synthesis of [BMIm]Br,and 92.17～97.27kJ/mol for synthesis of Br.Microwave radiation could take effect by increasing reaction frequency factors instead of changing the reaction mechanism and activation energy.