Catalysis of the photodecomposition of carbon tetrachloride in ethanol by an Amberlite anion exchange resin

The chloride form of the polystyrene-divinylbenzene anion exchange resin Amberlite IRA-900 was found to catalyze the photodecomposition of carbon tetrachloride in ethanol at wavelengths above 350 nm. With sulfate, bromide, and perchlorate as counterions, the resin was inactive. The major products are acetaldehyde, phosgene, chloroform, and hydrogen chloride. The photoreaction is much slower under 1.0 atm O-2 than under air, while in deoxygenated solutions it is also much slower and produces no phosgene. Much of the observed behavior can be explained by a model in which the poly(styrene-co-divinylbenzene) matrix absorbs light and transfers energy to CCl4, which undergoes photodissociation, assisted by a chloride ion to stabilize the chlorine atom as Cl-2(-). Two major reaction channels for the trichloromethyl radicals produced by photodissociation are proposed, one in which CCl3 abstracts hydrogen from ethanol and the other involving addition of O-2 to form trichloromethylperoxy radicals. (C) 2010 Elsevier Inc. All rights reserved.