邻亚甲基苯醌与丙烯Diels-Alder反应的密度泛函理论研究

A DFT Characterization of the Mechanism for the Cycloaddition Reaction between o-Quinone Methides and Propylene

采用量子化学密度泛函理论(DFT)在(U)B3LYP/6-31G*水平上对邻亚甲基苯醌与丙烯的Diels-Alder反应进行了理论研究,利用能量梯度法对反应途径上各驻点的构型进行了全优化,对过渡态进行了振动分析确认.对其可能的4个反应通道进行了研究,4个反应通道的活化能垒的顺序是XR<NR<NM<XM.其中ortho型反应通道优于meta型反应通道,这表明该反应具有较强的ortho区域选择性.计算结果表明,溶剂效应能够降低反应活化能垒的高度,同时增加了反应过程中键形成的不协同性.

Four possible Diels-Alder reaction channels between o-quinone methides and propylene have been studied by means of Density Functional Theory （DFI＇） at the （U）B3LYP/6 -31 G ＊ theory level. The activation barriers of the four channels take a quantitative sequence of XR 〈 NR 〈 NM 〈 XM. On the basis of frontier molecule orbit and comparison of the activation energies for different reaction pathways, the ortho attack modes present transition structures more stable than the meta ones. The calculations show that the effect of solvent decreases the activation energy and increases the asynchronicity.