Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (09): 1923-1930.doi: 10.3866/PKU.WHXB201306281

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

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).

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