Baeyer-Villiger Oxidation of Cyclic Ketones by Using Tin-Silica Pillared Catalysts

The Baeyer–Villiger oxidation is an important transformation of ketones into esters and particularly for cyclic ketones to lactones. We report here preparation and catalytic activity of layered Sn–silicate catalysts and mesoporous ordered silica catalysts in this reaction. Sn was introduced by using so-called tin–silica pillaring or by impregnation with a mixture of tetraethylorthosilicate and tin(IV) alkoxide. The prepared catalysts were characterized by XRD, N2 physisorption, SEM, UV/Vis, and inductively coupled plasma optical emission spectroscopy (ICP-OES) techniques and the catalysts were studied in the Baeyer–Villiger oxidation of cyclopentanone, norcamphor, and 2-adamantanone with aqueous hydrogen peroxide. Norcamphor and 2-adamantanone were oxidized easily with selectivity up to 99 %. Sn-MS and IPC-1-SnPI materials exhibited the highest conversions (e.g., norcamphor: Sn-MS 37 %, IPC-1-SnPI 36 % after 8 h vs. Sn-MCM-41 22 %). On the other hand, oxidation of cyclopentanone suffered from product hydrolysis to the corresponding 4-hydroxybutanoic acid.