title: A novel model to predict gas-phase hydroxyl radical oxidation kinetics of polychlorinated compounds.
abstract: In this study, a novel model based on aromatic meta-substituent grouping was presented to predict the second-order rate constants (k) for OH oxidation of PCBs in gas-phase. Since the oxidation kinetics are dependent on the chlorination degree and position, we hypothesized that it may be more accurate for k value prediction if we group PCB congeners based on substitution positions (i.e., ortho (o), meta (m), and para (p)). To test this hypothesis, we examined the correlation of polarizability (α), a quantum chemical based descriptor for k values, with an empirical Hammett constant (σ+) on each substitution position. Our result shows that α is highly linearly correlated to ∑σo,m,p+based on aromatic meta-substituents leading to the grouping based predictive model. With the new model, the calculated k values exhibited an excellent agreement with experimental measurements, and greater predictive power than the quantum chemical based quantitative structure activity relationship (QSAR) model. Further, the relationship of α and ∑σo,m,p+for PCDDs congeners, together with highest occupied molecular orbital (HOMO) distribution, were used to validate the aromatic meta-substituent grouping method. This newly developed model features a combination of good predictability of quantum chemical based QSAR model and simplicity of Hammett relationship, showing a great potential for fast and computational tractable prediction of k values for gas-phase OH oxidation of polychlorinated compounds.
authors.affiliation: Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Luo
authors.affiliation: Grand Water Research Institute-Rabin Desalination Laboratory, Wolfson Faculty of Chemical Engineering, Technion-Israel Institute of Technology, Technion City, Haifa, 32000, Israel.
authors.forename: Zongsu
authors.initials: Z
authors.lastname: Wei
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States.
authors.forename: Richard
authors.initials: R
authors.lastname: Spinney
authors.affiliation: Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China.
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Chai
authors.affiliation: Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China. Electronic address: xiao.53@csu.edu.cn.
authors.forename: Ruiyang
authors.initials: R
authors.lastname: Xiao
mesh_terms: D004785:Environmental Pollutants / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D021281:Quantitative Structure-Activity Relationship
chemical_list: D004785:Environmental Pollutants; D005740:Gases; D017665:Hydroxyl Radical; D011078:Polychlorinated Biphenyls
keywords: Hammett constant; Meta–substituents; Polarizability; Polychlorinated compounds; QSAR; Second–order rate constants