Regioselectivity in the Semiconductor-Mediated Photooxidation of 1,4-Pentanediol.

摘要

Optimum conditions have been established for the selective semiconductor-photocatalyzed oxidation by long-wavelength ultraviolet light of the primary alcohol functionality in 1,4-pentanediol. On platinized (2%) Titanium dioxide powder suspended in oxygenated aqueous (4 vol %) acetonitrile, the initial rate ratio for oxidation of the primary/secondary alcohol site was >7. Analysis of further oxidation products allowed for mechanistic delineation of the course of the semiconductor-mediated reaction. The selectivity is attributed to the essential role of adsorption, with the critical photoinduced electron transfer occuring at the surface of the irradiated particle. Zr.O2 and Stannic oxide samples were much less active than TiO2 as photocatalysts. The effects of oxygen pressure, metal cocatalyst loading, and water content of acetonitrile are discussed. Keywords: Photoelectrochemistry. Reprints. (AW)