Grignard Reagents in Solution: Theoretical Study of the Equilibria and the Reaction with a Carbonyl Compound in Diethyl Ether Solvent
Grignard Reagents in Solution: Theoretical Study of the Equilibria and the Reaction with a Carbonyl Compound in Diethyl Ether Solvent
复制标题
溶液中的格氏试剂：二乙醚溶剂中平衡及与羰基化合物反应的理论研究
DOI：
10.1021/jp9009788
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发表时间：
2009
影响因子：
2.9
通讯作者：
S. Kato
中科院分区：
文献类型：
--
作者：
T. Mori;S. Kato
本文从理论上研究了格氏试剂CH_3MgCl和CH_3MgBr在乙醚（Et_2O）溶剂中的平衡以及它们与丙酮的反应。为了描述Et 2 O溶剂中的平衡和反应，我们采用参考相互作用位点模型自洽场方法和二阶Møller-Plesset微扰（RISM-MP2）自由能梯度方法。由于溶剂分子强烈协调的Grignard试剂，我们构建了一个集群模型，包括几个Et 2 O分子的量子力学区域和嵌入到本体溶剂。我们建议，而不是传统上接受的环状二聚体，线性形式的二聚体是稳定的单体对，并参与平衡。对于与丙酮的反应，两个重要的反应路径（即，单体和线性二聚体路径）。结果表明，Grignard试剂与丙酮的反应是通过线性二聚反应途径进行的，单体反应的势垒高度远高于线性二聚反应的势垒高度，并考察了反应过程中溶剂化结构的变化.根据自由能的计算结果，讨论了格氏试剂与脂肪酮在Et_2O溶剂中的反应机理。
The equilibria of Grignard reagents, CH3MgCl and CH3MgBr, in diethyl ether (Et2O) solvent as well as the reaction of the reagents with acetone are studied theoretically. To describe the equilibria and reactions in Et2O solvent, we employ the reference interaction site model self-consistent field method with the second-order Møller−Plesset perturbation (RISM-MP2) free energy gradient method. Since the solvent molecules strongly coordinate to the Grignard reagents, we construct a cluster model by including several Et2O molecules into the quantum mechanical region and embed it into the bulk solvent. We propose that, instead of the traditionally accepted cyclic dimer, the linear form of dimer is as stable as the monomer pair and participates in the equilibria. For the reaction with acetone, two important reaction paths (i.e., monomeric and linear dimeric paths) are studied. It is found that the barrier height for the monomeric path is much higher than that for the linear dimeric path, indicating that the reaction of the Grignard reagent with acetone proceeds through the linear dimeric reaction path. The change of solvation structure during the reaction is examined. On the basis of the calculated free energy profiles, the entire reaction mechanisms of the Grignard reagents with aliphatic ketones in Et2O solvent are discussed.