Photocatalytic Degradation of Dichloromethane by Chlorocuprate(II) Ions

Near UV irradiation of aerated solutions of (Et4N)2[CuCl4] in dichloromethane causes the decomposition of CH2Cl2, as evidenced by the buildup of HCl, C2H2Cl4, and peroxides. A net reduction to [CuCl2]− occurs in the early stages, but is later reversed. In CH2Cl2, [CuCl4]2− is in equilibrium with [Cu...

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Veröffentlicht in:Inorganic chemistry 2008-08, Vol.47 (15), p.7029-7034
Hauptverfasser: Doyle, Kevin J, Tran, Huy, Baldoni-Olivencia, Miguel, Karabulut, Merve, Hoggard, Patrick E
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Sprache:eng
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Zusammenfassung:Near UV irradiation of aerated solutions of (Et4N)2[CuCl4] in dichloromethane causes the decomposition of CH2Cl2, as evidenced by the buildup of HCl, C2H2Cl4, and peroxides. A net reduction to [CuCl2]− occurs in the early stages, but is later reversed. In CH2Cl2, [CuCl4]2− is in equilibrium with [Cu2Cl6]2−, and only the latter species is photoactive. The decomposition is initiated by the photodissociation of chlorine atoms, which propagate to peroxy radicals, CHCl2OO. Experimental evidence, including a linear dependence of the decomposition rate on the incident light intensity and on the fraction of light absorbed by [Cu2Cl6]2−, is consistent with a mechanism in which CHCl2OO is reduced by electron transfer from [CuCl2]−, following which protonation yields CHCl2OOH. The hydroperoxide accumulates during irradiation and it too can reoxidize [CuCl2]−. The quantum yield for HCl production at the outset of irradiation at 313 nm is 1.3 mol/einstein, based on the fraction of light absorbed by [Cu2Cl6]2−.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic800684v