氯取代基对经典Diels-Alder反应影响的密度泛函研究

DFT study on the effects of chlorine substituent on the classical Diels-Alder reaction

使用密度泛函理论研究了氯取代基对经典Diels-Alder反应势能曲线的影响.结果表明:在氯取代基存在时,乙烯与1,3-丁二烯的Diels-Alder反应中各个稳定点的关键键长一定程度上变短;反应中氯取代基降低了乙烯的LUMO能量,反应能垒有所降低,反应过程中各个稳定点的相对吉普斯自由能降低;顺式-1,3-丁二烯更容易反应,该反应的协同机理能量上比双自由基分步机理更加有利.

The effects of chlorine group on the typical Diels-Alder reaction were investigated with density functional theory.The results indicated that the dominant bond lengths of the stationary poins of Diels-Alder reaction of ethylene and 1,3-butadiene are shorter than the unsubstituted one when the chlorine group was used;the lowest unoccupied orbital energy of ethylene was lowered by the chlorine group,which makes the Gibbs free energy of each stationary point and the activation barrier reduced;because activation barriers of concerted additions were higher,concerted additions of the substituted ethylene may occur more easily to the cis-1,3-butadiene.