Photodecomposition of Europium(III) Acetate and Formate in Aqueous Solutions

Article abstract of DOI:10.1021/j100318a027

The products obtained in the photodecomposition of europium(III) acetate and formate were determined quantitatively under various pH conditions.The two photoprocesses and the subsquent radical reactions have been found to proceed stoichiometrically with a cyclic redox reaction of the Eu³⁺/Eu²⁺ couple being the key process.In the acetate system, (1) redox reactions of methyl radical with Eu²⁺ and Eu³⁺ aquo ions are supported to occur with formation of methane and methanol, respectively; (2) carboxymethyl radical produced through hydrogen abstraction from acetic acid by the methyl radical probably regenerates acetic acid via the intermediate formed through the radical capture reaction by Eu²⁺ ion, followed by acidolysis reaction.In the formate system, (1) it was confirmed that the photoprocess is followed by a chain reaction in which carboxyl radicals generated in the primary process and hydrogen atoms produced through reduction by illuminated Eu²⁺ ion behave as chain carriers; (2) evolution of carbon dioxide gas is mostly ascribed to the disproportionation of carboxyl radical and the reduction of Eu³⁺ ion by carboxyl radical.In both systems, minor products are formed by redox and disproportionation radical reactions.