物理化学学报 >> 2013, Vol. 29 >> Issue (09): 1923-1930.doi: 10.3866/PKU.WHXB201306281

理论与计算化学 上一篇    下一篇

2,4-二氯苯氧乙酸代谢中的水解反应机理

李佳, 徐雯丽, 胡静, 凌敏, 姚建华   

  1. 中国科学院上海有机化学研究所, 上海 200032
  • 收稿日期:2013-02-06 修回日期:2013-06-27 发布日期:2013-08-28
  • 通讯作者: 姚建华 E-mail:yaojh@mail.sioc.ac.cn
  • 基金资助:

    国家自然科学基金项目(21072216);国家科技部“十二五”支撑项目(2011BAE06B05);国家重点基础研究发展规划项目(973)(2010CB126103)资助

Hydrolysis Reaction Mechanismof 2, 4-Dichlorophenoxy Acetic Acid Metabolism

LI Jia, XU Wen-Li, HU Jing, LING Min, YAO Jian-Hua   

  1. Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China
  • Received:2013-02-06 Revised:2013-06-27 Published:2013-08-28
  • Contact: YAO Jian-Hua E-mail:yaojh@mail.sioc.ac.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21072216), Ministry of Science and Technology of China (2011BAE06B05), and National Key Basic Research Program of China (973) (2010CB126103).

摘要:

2,4-二氯苯氧乙酸(2,4-D)是应用广泛的农用除草剂和植物生长素,在它的代谢过程中,涉及多种化学反应. 本文采用密度泛函理论B3LYP方法, 分别研究了它在代谢过程中的三条水解反应途径的机理. 研究结果表明: (I) 2,4-D水解反应有两种模式, C(1)―O键解离的氢转移和C―Cl键解离的氯被取代. (Ⅱ) C―Cl键的解离能垒明显低于C(1)―O键的解离能垒, 即水解速率较快, 反应动力学占优势. 在三条反应途径中, 途径(2)和(3)优先水解C―Cl键, 再水解C(1)―O键. 由于受反应速率的影响, 不同中间体在降解过程中的浓度有明显区别.(III) 对于水解反应,采用导体极化连续模型(CPCM)考虑溶剂化效应,可更合理地阐述水解反应机理.

关键词: 2,4-二氯苯氧乙酸, 密度泛函理论, 反应机理, 势能面, 水解, 溶剂化效应

Abstract:

2,4-Dichlorophenoxy acetic acid (2,4-D) is a herbicide and plant growth regulator that is widely applied inagriculture.Many chemical reactions takeplace inthemetabolismof 2,4-D. Herein, the hydrolysis reaction mechanismin 2,4-D metabolismwill be presented. In this study, a density functional theory approach, B3LYP, was employed toinvestigatethehydrolysis reaction mechanismalong three different paths. The computed results indicate that: (Ⅰ) there are two models of the hydrolysis reaction of 2,4-D. The dissociation mechanismof C(1)―O and C―Cl involve hydrogen transfer and Cl substitution, respectively. (Ⅱ) The energy barrier of C―Cl dissociation was lower and the dissociation showed advantageous dynamics. Two of the reaction paths that initiate the dissociation of C―Cl were primary reactions. The dissociation of C(1)―O was the last step in the primary reactions and had a higher energy barrier. In metabolism, the different intermediates have different concentrations, and this impacts on the reaction rate. (Ⅲ) In addition, it was necessary to consider the solvent effect to investigate the hydrolysis reaction. To characterize the solvent effect, the conductor-like polarizable continuum model (CPCM) was used to simulate the hydrolysis reaction with respect to the bond length and energy barrier.

Key words: 2,4-Dichlorophenoxy aceitc acid, Density functional theory, Reaction mechanism, Potential energy surface, Hydrolysis, Solvent effect

MSC2000: 

  • O642