高等学校化学学报 ›› 2015, Vol. 36 ›› Issue (10): 1954.doi: 10.7503/cjcu20150326

• 物理化学 • 上一篇    下一篇

叔丁氧基自由基引发氢迁移过程的理论研究

李悦, 方德彩()   

  1. 北京师范大学化学学院, 北京 100875
  • 收稿日期:2015-04-22 出版日期:2015-10-10 发布日期:2015-09-14
  • 作者简介:联系人简介: 方德彩, 男, 教授, 博士生导师, 主要从事计算化学研究. E-mail:dcfang@bnu.edu.cn
  • 基金资助:
    国家自然科学基金(批准号: 21373030 )资助

Density Functional Theory Studies on the t-Butoxyl Radical Mediated Hydrogen Atom Transfer Reactions

LI Yue, FANG Decai*()   

  1. College of Chemistry, Beijing Normal University, Beijing 100875, China
  • Received:2015-04-22 Online:2015-10-10 Published:2015-09-14
  • Contact: FANG Decai E-mail:dcfang@bnu.edu.cn
  • Supported by:
    † Supported by the National Natural Science Foundation of China(No.21373030)

摘要:

采用多种密度泛函理论方法(如CAM-B3LYP, M062x和wB97x方法), 并辅以极化连续介质模型对叔丁氧基自由基(tBuO·)与一系列胺类、 烷烃、 醇类和醚类反应物之间氢迁移反应的反应机理进行研究. 计算结果表明, 这类氢迁移反应主要受熵的控制. 通过对液相平动熵和气相平动熵得到的活化自由能数据进行对比, 可以看出, 使用气相平动熵得出的活化自由能明显偏高于实验测量值, 而以液相平动熵计算的反应活化自由能垒与实际结果相近, 3种方法对胺类和烷烃类反应物体系得出的结果更可靠, 对醇类和醚类反应物体系自由能垒则略低.

关键词: 叔丁氧基自由基, 氢迁移过程, 溶液中自由能, 反应速率常数

Abstract:

The reaction mechanisms of hydrogen abstractions from carbon by the t-butoxyl radical were investigated with several density functional theory(DFT) methods, such as CAM-B3LYP, M062x and wB97x. The results show that most of these reactions are dominated more by entropic than by enthalpic factor. The activation free energy barriers were calculated with both gas-phase translational entropy and solution translational entropy, in which those from ideal gas-phase translational entropy(output of Gaussian job) were much higher than the experimental estimations. It has been verified that free-energy barriers of amines and hydrocarbons reactions generated from solution translational entropies are close to the experimental measurements, but all these methods predict a little low free-energy barriers for alcohols and ethers reactions.

Key words: t-Butoxyl radical, Hydrogen abstraction, Free-energy barriers in solution, Rate constant

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