title: Chemical conversion pathways and kinetic modeling for the OH-initiated reaction of triclosan in gas-phase.
abstract: As a widely used antimicrobial additive in daily consumption, attention has been paid to the degradation and conversion of triclosan for a long time. The quantum chemistry calculation and the canonical variational transition state theory are employed to investigate the mechanism and kinetic property. Besides addition and abstraction, oxidation pathways and further conversion pathways are also considered. The OH radicals could degrade triclosan to phenols, aldehydes, and other easily degradable substances. The conversion mechanisms of triclosan to the polychlorinated dibenzopdioxin and furan (PCDD/Fs) and polychlorinated biphenyls (PCBs) are clearly illustrated and the toxicity would be strengthened in such pathways. Single radical and diradical pathways are compared to study the conversion mechanism of dichlorodibenzo dioxin (DCDD). Furthermore, thermochemistry is discussed in detail. Kinetic property is calculated and the consequent ratio of k add/k total and k abs/k total at 298.15 K are 0.955 and 0.045, respectively. Thus, the OH radical addition reactions are predominant, the substitute position of OH radical on triclosan is very important to generate PCDD and furan, and biradical is also a vital intermediate to produce dioxin.
authors: Environment Research Institute, Shandong University, Jinan 250100, China. zxue_117@126.com.
authors: Xue
authors: X
authors: Zhang
authors: Environment Research Institute, Shandong University, Jinan 250100, China. sdzhangcx@163.com.|Department of Resource and Environment, Binzhou University, Binzhou 256600, China. sdzhangcx@163.com.
authors: Chenxi
authors: C
authors: Zhang
authors: Environment Research Institute, Shandong University, Jinan 250100, China. sxmwch@sdu.edu.cn.
authors: Xiaomin
authors: X
authors: Sun
authors: Environment Research Institute, Shandong University, Jinan 250100, China. lingyan_k@163.com.
authors: Lingyan
authors: L
authors: Kang
authors: Environment Research Institute, Shandong University, Jinan 250100, China. zhaoyan08319@126.com.|School of Life Sciences, Qufu Normal University, Qufu 273165, China. zhaoyan08319@126.com.
authors: Yan
authors: Y
authors: Zhao
mesh_terms: D004147:Dioxins / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D011078:Polychlorinated Biphenyls / Q000737:chemistry; D014260:Triclosan / Q000737:chemistry*
chemical_list: D004147:Dioxins; D017665:Hydroxyl Radical; D014260:Triclosan; C503656:dichlorodibenzo-p-dioxin; D011078:Polychlorinated Biphenyls