Theoretical Study of Salt Effects on Diels-Alder Reaction of Cyclopentadiene With Methyl Vinyl Ketone Using RISM-SCF Theory
Theoretical Study of Salt Effects on Diels-Alder Reaction of Cyclopentadiene With Methyl Vinyl Ketone Using RISM-SCF Theory
复制标题
利用RISM-SCF理论研究盐对环戊二烯与甲基乙烯基酮Diels-Alder反应的影响
DOI：
10.1021/jp4091552
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发表时间：
2013
期刊：
影响因子：
3.3
通讯作者：
F. Hirata
中科院分区：
文献类型：
--
作者：
N. Yoshida;H. Tanaka;F. Hirata
使用参考相互作用位点模型自洽场 (RISM-SCF) 理论研究了盐对环戊二烯与甲基乙烯基酮的 Diels-Alder 反应的影响。通过向水溶剂中添加LiCl来加速反应速率。通过环戊二烯与甲基乙烯基酮配合物的几何优化，找到了内顺式、内反式、外顺式、外反式四种过渡态的结构。内反式结构在水和 LiCl 溶液中显示出最低的能量。 LiCl溶液中反应的活化能垒低于水中的反应活化能垒，与实验结果吻合较好。活化能垒的降低是由于反应物种类的不稳定造成的。 LiCl的盐效应使所有参与反应的物质因疏水效应而变得不稳定；然而，TS复合物中增加的疏水效应通过形成氢键而受到抑制，氢键与反应物甲基乙烯基酮相比更强。
Salt effects on the Diels–Alder reaction of cyclopentadiene with methyl vinyl ketone are investigated using reference interaction site model self-consistent field (RISM-SCF) theory. The rate of the reaction is accelerated by adding LiCl to the water solvent. The structures of four transition states,endo-cis,endo-trans,exo-cis,exo-trans, were found by geometry optimization of the cyclopentadiene and methyl vinyl ketone complexes. Theendo-trans structure shows the lowest energy in both water and LiCl solution. The activation barrier of the reaction in LiCl solution is lower than that in water, and the difference is in good agreement with that from experiments. The decrease in the activation barrier arises from destabilization of the reactant species. The salt effect of LiCl makes all species concerning the reaction unstable by the hydrophobic effect; however, the increased hydrophobic effect in the TS complexes is suppressed by making the hydrogen bond, which is stronger compared with the reactant methyl vinyl ketone.