Selective photooxidation of diols with silica bound image

The decatungstate anion image has been heterogenized on silica previously functionalized with different ammonium cations covalently bound to the surface of the solid support. These materials are investigated as photocatalysts for the oxygen-assisted oxidation of 1,3-butanediol and 1,4-pentanediol. Product distribution and adsorption experiments indicate that the polarity of the environment surrounding the photoactive anion plays a crucial role in controlling the adsorption of diols on the surface and, consequently, their reaction with the photoexcited decatungstate. Proper reaction conditions are found for obtaining more than 90% of 4-hydroxy-2-butanone from 1,3-butanediol and for stopping the oxidation of 1,4-pentanediol to 4-hydroxypentanal with good yield. The employed photocatalysts present a very good stability in repeated experiments.