Influence of Hydrophilicity on the Snβ-Catalyzed Baeyer-Villiger Oxidation of Cyclohexanone with Aqueous Hydrogen Peroxide

Sn beta zeolites are amongst the most effective heterogeneous catalysts for the Baeyer-Villiger (BV) oxidation of ketones with aqueous hydrogen peroxide (H2O2). The high selectivity is rooted in the activation of the carbonyl substrate through interaction with the isolated Sn-IV sites. However, these sites are also accessible to other molecules in the reaction mixture (in particular the co-solvent and product). In this contribution, we report the impact of competitive adsorption on the Sn beta-catalyzed BV oxidation of cyclohexanone with aqueous H2O2. We furthermore prepared a series of Sn Chi zeolites with varying amounts of framework silanols and quantified their hydrophilicities with water adsorption and IR experiments. By correlating the results with catalytic data, we show that Sn beta zeolites with an intermediate hydrophilicity achieve the highest activity. Our adaptable post-synthetic synthesis allows us to tune the material synthesis, resulting in enhanced activity compared with conventional hydrothermal Sn beta.