| Abstract |
New decatungstate W10O324-catalysts supported on SiO2 or Al2O3 were prepared. The aim of this study is to characterize the photocatalytic properties of (n-Bu4N)4W10O32/Al2O3 and (n-Bu4N)4W10O32/SiO2 in the oxidation of benzyl-alcohols in the presence of molecular oxygen. To this purpose we initially utilized 1-phenyl-ethanol as representative aryl alcohol, to examine the activity of the catalysts. The catalysts were stable under photoirradiation conditions, retained their activity in repeated catalytic cycles, while acetonitrile and acetone were found to be the most appropriate solvents for high catalytic action. The results, are indicative of a Hydrogen Atom Transfer (HAT) process in the rate determining step, as the major mechanistic pathway for the photooxidation of aryl alcohols, while to a lesser extent Electron Transfer (ET) process is also contributing. The materials described on this study, were shown to be effective catalysts for the oxidation of a series of primary and secondary benzyl alcohols, with molecular oxygen. Our experiments demonstrated that up to 100% conversions can be achieved in chemoselective manner, thus providing rapid access to a variety of aryl ketones. Compared to the homogeneous catalytic processes, the catalysts described in this work offer the advantages of simple recovery from the treated solution, stable activity in subsequent catalytic cycles, and a very low input of metals into the treated solutions.
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Εφαρμογή νέων υλικών W10O324-/SiO2 και W10O324-/Al2O3 στην ετερογενή καταλυτική φωτοξείδωση βενζυλο αλκοολών
