Predicting gaseous reaction rates of short chain chlorinated paraffins with ·OH: overcoming the difficulty in experimental determination.
Short chain chlorinated paraffins (SCCPs) are under evaluation for inclusion in the Stockholm Convention on persistent organic pollutants. However, information on their reaction rate constants with gaseous ·OH (kOH) is unavailable, limiting the evaluation of their persistence in the atmosphere. Experimental determination of kOH is confined by the unavailability of authentic chemical standards for some SCCP congeners. In this study, we evaluated and selected density functional theory (DFT) methods to predict kOH of SCCPs, by comparing the experimental kOH values of six polychlorinated alkanes (PCAs) with those calculated by the different theoretical methods. We found that the M06-2X/6-311+G(3df,2pd)//B3LYP/6-311 +G(d,p) method is time-effective and can be used to predict kOH of PCAs. Moreover, based on the calculated kOH of nine SCCPs and available experimental kOH values of 22 PCAs with low carbon chain, a quantitative structure-activity relationship (QSAR) model was developed. The molecular structural characteristics determining the ·OH reaction rate were discussed. logkOH was found to negatively correlate with the percentage of chlorine substitutions (Cl%). The DFT calculation method and the QSAR model are important alternatives to the conventional experimental determination of kOH for SCCPs, and are prospective in predicting their persistence in the atmosphere.
Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology , Dalian 116024, China.
Chao
C
Li
Hong-Bin
HB
Xie
Jingwen
J
Chen
Xianhai
X
Yang
Yifei
Y
Zhang
Xianliang
X
Qiao
D000393:Air Pollutants / Q000737:chemistry*; D001272:Atmosphere / Q000737:chemistry; D002713:Chlorine / Q000737:chemistry; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry; D010232:Paraffin / Q000737:chemistry*; D011446:Prospective Studies; D021281:Quantitative Structure-Activity Relationship
D000393:Air Pollutants; D006843:Hydrocarbons, Chlorinated; D017665:Hydroxyl Radical; D002713:Chlorine; D010232:Paraffin