Application of a dioxo-molybdenum(VI) complex anchored on TiO2 for the photochemical oxidative decomposition of 1-chloro-4-ethylbenzene under O2

The catalytic activity of dioxo-molybdenum(VI)-dichloro[4,4′-dicarboxylato-2,2′-bipyridine] covalently anchored through the carboxylate function to the surface of TiO2 has been tested for the oxidative degradation of 1-chloro-4-ethylbenzene in MeCN solution under argon and UV irradiation (λ = 254 nm). After 4–5 h of photochemical reaction, the Mo complex was reoxidized in the presence of O2 in the dark, and then the reaction was continued under argon. The reaction proceeds by the intermediate formation of 4′-chloroacetophenone that undergoes further decomposition to chlorobenzene, plus small amounts of oxygen-containing organochlorine compounds, CO2 and H2O. Similar results were obtained for the decomposition of 4′-chloroacetophenone under the same conditions, which also gave chlorobenzene as one of the main products. The ratio of [final product]/[Mo complex] increases during the decomposition of 1-chloro-4-ethylbenzene (up to 350–400% for 30–35 h of reaction), which provides evidence of a catalytic process. The probable photochemical reactions are discussed.