title: Production of hydroxylated polybrominated diphenyl ethers (OH-PBDEs) from bromophenols by manganese dioxide.
abstract: Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are of significant concern because of their enhanced toxicological effects compared to PBDEs. Research to date has attributed the origin of OH-PBDEs to biological metabolism of PBDEs and natural production in the environment. However, it is unclear how OH-PBDEs are formed naturally. In this study, we explored the formation of OH-PBDEs via the oxidative transformation of simple bromophenols (BPs, e.g., 4-BP, 2,4-DBP, and 2,4,6-TBP) by birnessite (δ-MnO2). Results showed that OH-PBDEs were readily produced by δ-MnO2 with BPs as precursors. For example, oxidation of 2,4-DBP by δ-MnO2 yielded 2'-OH-BDE-68 and 2',5'-OH-BDE-25. Other OH-PBDEs, such as 6-OH-BDE-13, 2',5'-OH-BDE-3, 4'-OH-BDE-121, and 2',5'-OH-BDE-69, were detected from the reaction with 4-BP and 2,4,6-TBP. The formation of OH-PBDEs likely resulted from the oxidative coupling of bromophenoxy radicals. Mild acidic conditions enhanced while coexisting cations (e.g., Na(+), Mg(2+), and Ca(2+)) suppressed the transformation. Given the ubiquity of BPs and δ-MnO2, oxidation of BPs by δ-MnO2 and other metal oxides is likely an abiotic route for the formation of OH-PBDEs in the environment.
authors.affiliation: College of Biological and Environmental Engineering, Zhejiang University of Technology , Hangzhou 310032, People's Republic of China.
authors.forename: Kunde
authors.initials: K
authors.lastname: Lin
authors.forename: Chao
authors.initials: C
authors.lastname: Yan
authors.forename: Jay
authors.initials: J
authors.lastname: Gan
mesh_terms: D055768:Halogenated Diphenyl Ethers / Q000737:chemistry*; D006900:Hydroxylation; D007700:Kinetics; D017895:Manganese Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*
chemical_list: D055768:Halogenated Diphenyl Ethers; D017895:Manganese Compounds; D010087:Oxides; C505018:birnessite; C016552:manganese dioxide