title: New insight into the formation mechanism of PCDD/Fs from 2-chlorophenol precursor.
abstract: Chlorophenols are known as precursors of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The widely accepted formation mechanism of PCDD/Fs always assumes chlorophenoxy radicals as key and important intermediates. Based on the results of density functional theory calculations, the present work reports new insight into the formation mechanism of PCDD/Fs from chlorophenol precursors. Using 2-chlorophenol as a model compound of chlorophenols, we find that apart from the chlorinated phenoxy radical, the chlorinated phenyl radical and the chlorinated α-ketocarbene also have great potential for PCDD/F formation, which has scarcely been considered in previous literature. The calculations on the self- and cross-coupling reactions of the chlorophenoxy radical, the chlorinated phenyl radical and the chlorinated α-ketocarbene show that the formations of 1-MCDD, 1,6-DCDD, 4,6-DCDF, and 4-MCDF are both thermodynamically and kinetically favorable. In particular, some pathways involving the chlorinated phenyl radicals and the chlorinated α-ketocarbene are even energetically more favorable than those involving the chlorophenoxy radical. The calculated results may improve our understanding for the formation mechanism of PCDD/Fs from chlorophenol precursors and be informative to environmental scientists.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, Shandong University , Jinan, 250100, PR China.
authors.forename: Wenxiao
authors.initials: W
authors.lastname: Pan
authors.forename: Dongju
authors.initials: D
authors.lastname: Zhang
authors.forename: Zhe
authors.initials: Z
authors.lastname: Han
authors.forename: Jinhua
authors.initials: J
authors.lastname: Zhan
authors.forename: Chengbu
authors.initials: C
authors.lastname: Liu
mesh_terms: D001572:Benzofurans / Q000737:chemistry*; D002733:Chlorophenols / Q000737:chemistry*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*
chemical_list: D001572:Benzofurans; D002733:Chlorophenols; D000072317:Polychlorinated Dibenzodioxins; D011108:Polymers; C016068:polychlorodibenzofuran; C030683:2-chlorophenol