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

Abstract

The FeCl4(-) ion, heterogenized on a Dowex ion exchange resin, catalyzes the aerobic photodecomposition of neat CH2Cl2. Phosgene production was used to characterize the extent of decomposition, although it appears to be a secondary product from the decomposition of chloroform, which is suggested to arise from the reaction of dichloromethanol with hydrogen chloride. The yield of CHCl3 increases when the production of phosgene is suppressed by water or acetonitrile. CuCl4(2-), likewise heterogenized on Dowex, is photocatalytically inactive.

Photocatalysis of ethanol oxidation by tetrachloroferrate(III) supported on Dowex 2‐X8

“…The data are consistent with a photooxidation process involving a hydroperoxide, as has been proposed for the oxidative photodecomposition of dichloromethane catalyzed by FeCl 4 À on Dowex [11] and the oxidative photodecomposition of chloroform by homogeneous FeCl 4 À . [12] As was proposed for those systems, the reaction can be expected to be initiated through photodissociation of a chlorine atom following excitation into a LMCT band.…”

“…[2] With the objective of photooxidizing alcohols using a heterogeneous catalyst that absorbs light in the visible part of the spectrum, we investigated FeCl 4 À heterogenized on a Dowex 2-X8 anion exchange resin. The lowest lying ligand-to-metal charge transfer (LMCT) band in the FeCl 4 À spectrum is centered at approximately 360 nm, [11,12] with a significant tail into the blue. There has been relatively little use of tetrachloroferrate(III) as a photooxidation catalyst, [11] although FeCl 3 , the LMCT band for which is approximately 20 nm further into the UV, [12,13] has been used for this purpose both homogeneously [4,[14][15][16][17] and heterogeneously.…”

“…The lowest lying ligand-to-metal charge transfer (LMCT) band in the FeCl 4 À spectrum is centered at approximately 360 nm, [11,12] with a significant tail into the blue. There has been relatively little use of tetrachloroferrate(III) as a photooxidation catalyst, [11] although FeCl 3 , the LMCT band for which is approximately 20 nm further into the UV, [12,13] has been used for this purpose both homogeneously [4,[14][15][16][17] and heterogeneously. [13] Maldotti et al reported the use of heterogenized tetrachloroferrate (III) to photochemically oxidize or chlorinate cycloalkanes stoichiometrically, the outcome depending on experimental conditions, [18] regenerating FeCl 4 À with hypochlorite ion in a separate process.…”

Photodecomposition of Chloroform Catalyzed by Unmodified MCM‐41 Mesoporous Silica

“…An obvious question from the results obtained is why ordinary silica gel showed no photocatalytic activity while mesoporous silica was even more active than other heterogeneous catalysts for chlorocarbon photodegradation that we have studied . It is unlikely that photophysical differences are responsible for this, as the two types of silica surface should have similar photophysical properties.…”

Photocatalysis of Chloroform Decomposition by Tetrachlorocuprate (II) on Dowex 2‐X8

“…When heterogenized on a Dowex anion exchange resin, loses its ability to catalyze the photodecomposition of CH 2 Cl 2 , possibly because the equilibrium with is unfavorable on the surface of the anion exchange resin. We find, however, that heterogenized does catalyze the photodecomposition of chloroform, which is the subject of this study.…”