- Photoreductive debromination of decabromodiphenyl ether by pyruvate
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Polybrominated diphenyl ethers (PBDEs) have aroused highly environmental concerns because of their toxicity and ubiquitousness in the biological and environmental system. Here, we report that decabromodiphenyl ether (BDE209) undergoes efficient reductive debromination reaction by pyruvate under UV irradiation (>360 nm). The photoreductive degradation kinetics of BDE209 has been further investigated under different reaction conditions. The debromination reactions occur in a stepwise process, producing a series of lower brominated congeners. The debromination shows unconspicuous position-selective property. The possible photoreductive mechanism has been proposed by UV-vis and kinetic isotope effect (KIE). This study not only provides a potential application of removal of PBDEs contaminations but also provides some information for the fate of PBDEs in environment.
- Jiang, Zhaowu,Linghu, Wensheng,Li, Yimin,Sun, Chunyan
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- Photochemical decomposition of 15 polybrominated diphenyl ether congeners in methanol/water
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The photochemical degradation of polybrominated diphenyl ethers (PBDE) with different degrees of bromination was studied. The photochemical degradation of 15 individual PBDE substituted with 4-10 bromine atoms was studied in methanol/water (8:2) by UV light in the sunlight region. Nine of these were also studied in pure methanol, and four of the nine PBDE were studied in tetrahydrofuran (THF). The reaction rate was dependent on the solvent in such a way that the reaction rate in a methanol/watersolution was consistently ～ 1.7 times lower than in pure methanol and 2-3 times lower than in THF. The quantum yields in the methanol/water solution ranged from 0.1 to 0.3. Photolysis of BDE-209 in methanol/water (80:20) produced decomposition products of lower PBDE and polybrominated dibenzofurans. Photolysis of decaBDE in methanol/water, pure methanol, THF, and water containing dissolved humanic substances gave rise to an almost identical set of products, although in the latter experiment, a higher proportion of pentaBDF was observed.
- Eriksson, Johan,Green, Nicholas,Marsh, Goeran,Bergman, Ake
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- Rapid, photocatalytic, and deep debromination of polybrominated diphenyl ethers on Pd-TiO2: Intermediates and pathways
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Titanium dioxide with surface-loaded palladium (Pd-TiO2) was able to easily remove all ten bromine atoms from decabromodiphenyl ether (BDE209) within 1 h under the irradiation of sunlight or an artificial light source. By contrast, fewer than three bromine atoms were eliminated on the pristine TiO2 even with prolonged irradiation (5 h). During the photocatalytic debromination, moreover, the formed BDE intermediates exhibited a significant difference between the Pd-TiO2 and pristine TiO 2 systems, and much less position selectivity for the debromination on Pd-TiO2 was observed than that on the pristine TiO2 surface. For another polybrominated diphenyl ether (BDE15), pristine TiO 2 was incapable of its photocatalytic reduction, whereas the loading of Pd enabled its debromination to diphenyl ether within 20 min. In addition, an evident induction period appeared in the photocatalytic debromination of BDE15 on Pd-TiO2. The experiments imply that the Pd-cocatalyzed effect changes significantly the photocatalytic reductive debromination pathways.
- Li, Lina,Chang, Wei,Wang, Ying,Ji, Hongwei,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
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supporting information
p. 11163 - 11170,8
(2015/02/02)
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- PREPARATION OF DECAHALODIPHENYL OXIDE
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This invention provides a process of preparing reaction-derived decahalodiphenyl oxide of high purity. The process comprises cofeeding separate feeds of (a) diphenyl oxide and/or partially brominated diphenyl oxide and (b) bromine chloride, bromine chloride and bromine, or bromine chloride and chlorine to a refluxing reaction mixture comprising bromine and at least one Lewis acid bromination catalyst so that high purity decahalodiphenyl oxide is formed.
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Page/Page column 12
(2008/06/13)
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- PREPARATION OF HIGH ASSAY DECABROMODIPHENYL OXIDE
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Process technology for producing very pure reaction-derived decabromodiphenyl oxide is described. Diphenyl oxide or partially brominated diphenyl oxide or a mixture of either or both of these is fed substantially continuously over a period of about 2 to about 12 hours into a reactor containing an excess of refluxing bromine containing Lewis acid bromination catalyst, and substantially concurrently reducing the content of hydrogen bromide present in the reactor whereby a decabromodiphenyl oxide product having a purity of over 99%, preferably 99.5% or more, is formed in the reactor.
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Page/Page column 8-9
(2008/06/13)
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