大学化学 >> 2022, Vol. 37 >> Issue (7): 2108001.doi: 10.3866/PKU.DXHX202108001

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乙基溴化镁与二异丙基酮反应的计算化学研究

黄职钱, 杨一莹, 马玉臣(), 张冬菊()   

  • 收稿日期:2021-08-01 录用日期:2021-09-07 发布日期:2021-10-25
  • 通讯作者: 马玉臣,张冬菊 E-mail:myc@sdu.edu.cn;zhangdj@sdu.edu.cn
  • 作者简介:张冬菊, Email: zhangdj@sdu.edu.cn
    马玉臣, Email: myc@sdu.edu.cn
  • 基金资助:
    国家自然科学基金面上项目(21773139);国家自然科学基金面上项目(21833004);山东省自然科学基金青年基金项目(ZR2020QB077)

Computational Chemistry on Reactions of Ethylmagnesium Bromide with Diisopropyl Ketone

Zhiqian Huang, Yiying Yang, Yuchen Ma(), Dongju Zhang()   

  • Received:2021-08-01 Accepted:2021-09-07 Published:2021-10-25
  • Contact: Yuchen Ma,Dongju Zhang E-mail:myc@sdu.edu.cn;zhangdj@sdu.edu.cn

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摘要：

格氏试剂与羰基化合物的亲核加成反应是构建C-C键的经典反应，该反应通常伴生的副反应主要包括羰基化合物的还原反应、烯醇化反应等。以乙基溴化镁(EtMgBr)与二异丙基酮(CO(iPr)2)的反应为例，通过量子化学计算研究了格氏试剂与羰基化合物的亲核加成反应、还原反应和烯醇化反应。结果表明，通过Schlenk平衡形成的二乙基镁(MgEt2)比EtMgBr更容易与CO(iPr)2反应，与教科书中定性描述的反应机理明显不同；乙醚溶剂对反应性能有重要影响，特别是更有利于亲核加成反应；计算的三个反应的能垒差可以合理解释实验所观察的主产物与副产物的产率比。

关键词: 格氏试剂, 羰基化合物, 亲核加成, 还原, 烯醇化

Abstract:

The nucleophilic addition of Grignard reagents with carbonyl compounds is a classical reaction to construct C-C bonds, which is frequently accompanied by side-reactions, mainly including the enolization and reduction of carbonyl compounds. To explore the molecular mechanism of these three reactions, quantum chemical calculations were performed on the reaction of ethylmagnesium bromide (EtMgBr) with diisopropyl ketone (CO(iPr)2), a prototypical reaction of Grignard reagents with carbonyl compounds. It is found that diethyl magnesium (MgEt2) obtained from the Schlenk equilibrium of EtMgBr, is more active toward CO(iPr)2 than EtMgBr, which is generally described as the virtual active species in the textbook. The diethylether is shown to play a substantial role in the reactivity, especially in favor of nucleophilic addition reaction. The calculated energy barriers of the three reactions can rationalized the experimentally observed main product to by-products yield ratio.

Key words: Grignard reagents, Carbonyl compounds, Nucleophilic addition, Reduction, Enolization