Photocatalytic Degradation of Dichloromethane by Chlorocuprate(II) Ions

Abstract

Near UV irradiation of aerated solutions of (Et 4N) 2[CuCl 4] in dichloromethane causes the decomposition of CH 2Cl 2, as evidenced by the buildup of HCl, C 2H 2Cl 4, and peroxides. A net reduction to [CuCl 2] (-) occurs in the early stages, but is later reversed. In CH 2Cl 2, [CuCl 4] (2-) is in equilibrium with [Cu 2Cl 6] (2-), and only the latter species is photoactive. The decomposition is initiated by the photodissociation of chlorine atoms, which propagate to peroxy radicals, CHCl 2OO. Experimental evidence, including a linear dependence of the decomposition rate on the incident light intensity and on the fraction of light absorbed by [Cu 2Cl 6] (2-), is consistent with a mechanism in which CHCl 2OO is reduced by electron transfer from [CuCl 2] (-), following which protonation yields CHCl 2OOH. The hydroperoxide accumulates during irradiation and it too can reoxidize [CuCl 2] (-). 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 [Cu 2Cl 6] (2-).

Photodecomposition of dichloromethane catalyzed by tetrachloroferrate(iii) supported on a Dowex anion exchange resin

“…Another hydrogen abstraction reaction may take place, 16,19,20 leading to dichloromethyl hydroperoxide:…”

Mechanistic Insights into the One‐Pot Synthesis of Propargylamines from Terminal Alkynes and Amines in Chlorinated Solvents Catalyzed by Gold Compounds and Nanoparticles

“…[15] The heterolytic thermal or photocatalytic degradation of CH 2 Cl 2 to HCl and CO under aerobic conditions has been described for heterogeneous catalysts and chlorocuprate ions. [16] The CÀCl bond activation described here represents an elegant example of the activation of CH 2 Cl 2 , which generates and transfers the methylene fragment catalytically (typically 5 mol % catalyst and amounts as low as 1 mol % for longer reaction times) under mild reaction conditions (50 8C). Au III complexes and Ag I salts have proven to be effective in similar C À Cl bond activations, [17] but details of these findings were never published.…”

Near-UV photolysis of μ-dibromotetrabromo- dipalladate(II) in chloroform

“…Halogen radicals may also be formed through photodissociation of a halometallate complex, which frequently may be achieved with near-UV or visible light [20,21]. Chlorine atoms photodissociated from a chlorometallate may cause the same kinds of reactions promoted by the direct photolysis of chloroform, and in addition, may catalyze the photodecomposition of chloroform by means of longer wavelength light than that required for direct photodegradation [20][21][22].…”

“…Chlorine atoms photodissociated from a chlorometallate may cause the same kinds of reactions promoted by the direct photolysis of chloroform, and in addition, may catalyze the photodecomposition of chloroform by means of longer wavelength light than that required for direct photodegradation [20][21][22].…”