N-甲基咪唑季铵化反应动力学研究

A kinetic study of quaternization of N-methyl imidazole

在50℃下,以异丙醇为反应溶剂,研究了N-甲基咪唑与卤代烷的反应动力学,得到反应总级数为二级,分反应级数各为一级;测得N-甲基咪唑与溴丁烷在50℃、55℃和60℃时的反应速率常数分别为0.092 4 L.mol-1.h-1、0.169 2 L.mol-1.h-1和0.322 8 L.mol-1.h-1,进而计算出反应的活化能为2.18×105J.mol-1;同时,测得N-甲基咪唑与溴乙烷、溴丁烷的反应速率常数分别为0.292 6 L.mol-1.h-1和0.169 2 L.mol-1.h-1,说明溴乙烷与N-甲基咪唑的季铵化较溴丁烷易于进行。

A study on the kinetics of quatemization of N - methyl imidazole with butyl bromide was carried out at 50℃ in isopropyl alcohol as solvent. The results showed that the overall reaction was of the second - order and the order of reaction for N - methyl imidazole and butyl bromide was first - order for each. The reaction rate constant at 50℃, 55℃ and 60℃ was 0.092 4 L· mol^- 1· h^-1, 0.169 2 L· mol^- 1·h^- 1 and 0.322 8 L·mol^- 1·h^-1, respectively. The activation energy of the quatemization between N- methyl imidazole and butyl bromide was 2.18 × 10^5 J·mol^-1. Further, the rate constant for the reaction between ethyl bromide and N - methyl imidazole obtained as 0.292 6 L·mol^- 1· h^- l, which indicates that the quatemization of ethyl bromide is easier than that of butyl bromide.