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A Theoretical Study on Reductive Debromination of Polybrominated Diphenyl Ethers
Guizhou Provincial Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment, Guizhou Normal University, Guiyang 550001, China
Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA
Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
* Author to whom correspondence should be addressed.
Received: 24 May 2012; in revised form: 8 July 2012 / Accepted: 18 July 2012 / Published: 24 July 2012
Abstract: Recent progress has been made in the reductive debromination of polybrominated diphenyl ethers (PBDEs) by nanoscale zero-valent iron (nZVI). To better understand the mechanism of this reaction, seven selected BDE congeners and their anions were investigated at the density functional theory (DFT) level using four different methods, including B3LYP/6-31G(d), B3LYP/6-31+G(d), B3LYP/6-31G(d,p) and B3LYP/6-311G(d,p). The cleaved C–Br bonds observed in the equilibrium structures of anionic PBDEs were adopted as the probe of the susceptible debromination position of PBDEs in the presence of nZVI, and the proposed major reaction pathways based on our calculations can satisfactorily conform to the reported experimental results. The debromination preference is theoretically evaluated as meta-Br > ortho-Br > para-Br. In addition, both the calculated frontier orbital energies and adiabatic electronic affinities were found to be highly related to their experimental reductive debromination rate constants. The highest linear regression coefficient was observed in the case using the energy of lowest unoccupied molecular orbital as the molecular descriptor obtained from B3LYP/6-31G(d) (R2 = 0.961, n = 7) or B3LYP/6-31G(d,p) (R2 = 0.961, n = 7). The results clearly showed the evidence of an electron transfer mechanism associated with this reductive debromination reaction.
Keywords: polybrominated diphenyl ethers; reductive debromination; radical anion; density functional theory; electron transfer
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MDPI and ACS Style
Hu, J.-W.; Zhuang, Y.; Luo, J.; Wei, X.-H.; Huang, X.-F. A Theoretical Study on Reductive Debromination of Polybrominated Diphenyl Ethers. Int. J. Mol. Sci. 2012, 13, 9332-9342.
Hu J-W, Zhuang Y, Luo J, Wei X-H, Huang X-F. A Theoretical Study on Reductive Debromination of Polybrominated Diphenyl Ethers. International Journal of Molecular Sciences. 2012; 13(7):9332-9342.
Hu, Ji-Wei; Zhuang, Yuan; Luo, Jin; Wei, Xiong-Hui; Huang, Xian-Fei. 2012. "A Theoretical Study on Reductive Debromination of Polybrominated Diphenyl Ethers." Int. J. Mol. Sci. 13, no. 7: 9332-9342.