Photochemical oxidation of aliphatic aldehydes by uranyl ions

Abstract

The photochemical oxidation of formaldehyde and acetaldehyde by Uranyl percholate in aqueous perchloric acid was studied three monochromatic wavelength, 365 mμ, 405 mμ and 436 mμ. The rate of Uranous ion formation was directly proportional to light intensity and light absorption fraction by the active species. Plots of reciprocal rates versus reciprocal aldehyde concentrations were linear with intercepts on the ordinates indicating complex formation between Uranyl ions and the aldehydes. Hydrogen ions had marked effect on the rates. The results are consistent with the hypothesis that there is complex formation between Uranyl ions and aldehyde and the excitation of the complex (active species) is the primary photochemical process and the excited complex docomposes by an electron transfer process yielding U4+ and substrate radical in a secondary dark reaction. Quantum yield for U4+ production increased with decreasing wavelength of light.