Original scientific paper

Theoretical and Experimental Approach for the Study of 2,4-Dichlorophenoxyacetic acid Photodegradation: C-O versus C-Cl Bond Dissociation Energies in the Gas Phase and Aqueous Medium

Jean-Jacques Aaron ; ITODYS, Université Paris Diderot (Paris 7), CNRS UMR 7086, Bâtiment Lavoisier, 15 rue Jean de Baïf, 75205 Paris Cedex 13, France; Université Paris-Est Marne la Vallée, Laboratoire G2I, 5 boulevard Descartes, Champs-sur-Marne, 77454 Marne-la -Vallée Cedex
Sandrine Irace Guigand ; ITODYS, Université Paris Diderot (Paris 7), CNRS UMR 7086, Bâtiment Lavoisier, 15 rue Jean de Baïf, 75205 Paris Cedex 13, France
Ljupco Pejov ; Institute of Chemistry, Faculty of Sciences and Mathematics, Ss Cyril and Methodius University, Arhimedova 5, PO Box 162, 1000 Skopje, Republic of Macedonia
Snežana Efremova-Aaron ; Department of Medical and Experimental Biochemistry, Faculty of Medicine, Ss Cyril and Methodius University, 50 Divizja 6, 1000 Skopje, Republic of Macedonia
Zoran Zdravkovski orcid.org/0000-0002-3644-8996 ; Institute of Chemistry, Faculty of Sciences and Mathematics, Ss Cyril and Methodius University, Arhimedova 5, PO Box 162, 1000 Skopje, Republic of Macedonia

Abstract

A theoretical, gradient-corrected Hartree-Fock-density functional theory (HF-DFT) approach was applied to the determination of the bond dissociation energy (BDE) for the photodegradation
processes of the 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide in the gas phase and in aqueous medium. According to the results of these calculations, the phenoxy C−O homolytic BDE value was found to be approximately two times lower than the corresponding C−Cl (2) and C−Cl (4) BDE ones, in both gas phase and under continuous solvation by water. An experimental study of the 2,4-D photodegradation reaction kinetics and photoproducts was also performed in water. At lower concentration, the formation of
only two photoproducts (2-Cl- and 4-Cl-phenoxyacetic acid) was observed, whereas at higher concentration, three photoproducts were formed, with 2,4-dichlorophenol as the third one. These photoproducts appeared competitively within about 40–80 min, and were eventually photodecomposed. The experimental
data are in good agreement with the results of our HF-DFT calculations.

Keywords

2,4-D herbicide; photodegradation; Hartree-Fock-density functional theory (HF-DFT) approach; bond dissociation energy processes

Hrčak ID:

56020

URI

https://hrcak.srce.hr/56020

Publication date:

15.7.2010.

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