Preparation of clay-supported Sn catalysts and application to Baeyer-Villiger oxidation

Clay-intercalated Sn catalysts were prepared by a conventional cation-exchange method and used for the Baeyer-Villiger oxidation of various ketones with hydrogen peroxide as an oxidant. The intercalation of monomeric Sn species into the clay interlayer was monitored by solid-state Li-7 MAS NMR. Solid-state Sn-119 MAS NMR and Sn K-edge XAFS analysis revealed that an isolated Sn species, such as [Sn-IV(OH)(x)(H2O)(5-x)]((4-x)+) (x = 0 3), was formed in the clay interlayers. Our clay-intercalated Sn catalysts showed extremely high performance in Bayer-Villiger oxidation and were also reusable without any significant loss of activity or selectivity.