烷基咪唑离子液体与甲苯相互作用的理论研究

在密度泛函理论中的B3LYP/6-31G（d,p）水平上研究了1-乙基-3-甲基咪唑四氟硼酸盐（[EMIM][BF4]）离子液体与甲苯相互作用的微观机制.研究结果表明,[EMIM]＋和[BF4]-离子对有两种稳定的构型,存在强的氢键及静电作用,[BF4]-离子靠近咪唑环2位H的构型比[BF4]-离子靠近咪唑环4、5位H处的构型稳定.甲苯与这两种构型的[EMIM][BF4]离子对形成π配位作用的分子复合物,咪唑环2位H对甲苯的吸附作用比咪唑环4、5位H对甲苯的吸附作用强,2位H表现出更高的活性.离子液体的存在能有效地降低甲苯的前线轨道能级差,表明甲苯在离子液体环境中更易发生催化反应.

A Theoretical Study on the Interaction Between Alkylimidazolium Ionic Liquids and Methylbenzene

The microcosmic interaction of the alkylimidazolium ionic liquids and methylbenzene was studied by the density functional theory at the B3LYP/6-31G（d,p） level.The results indicate that in the ~ and _ion Pair,there are two stable configurations with strong hydrogen bonds and electrostatic interaction.The configuration which _ion is close to 2-position H is more stable than the configuration which _ion is close to 4 and 5-position H.The interactions of the methylbenzene molecule with the ／／ ion Pair leads to the formation of π-complexes.The adsorption properties of 2-position H for methylbenzene are much stronger than those of 4 and 5-position H.The 2-position H shows the higher active.The ionic liquids can lower the energy gaps of frontier molecular orbital of methylbenzene,indicating that in ionic liquids the catalytic reaction of methylbenzene more easily proceeds.