Aerobic oxidations of α-pinene over cobalt-substituted polyoxometalate supported on amino-modified mesoporous silicates

Abstract Co-containing polyoxometalate [Bu 4 N] 4 H[PW 11 Co(H 2 O)O 39 ] (Co-POM) was supported on various NH 2 -modified mesoporous silicate matrixes (SBA-15, MCF, and SiO 2 -xerogel). The catalysts were characterized by elemental analysis, N 2 adsorption, DRS–UV, and FTIR spectroscopy. α -Pinene autoxidation and its co-oxidation with isobutyraldehyde (IBA) over the supported Co-POM catalysts have been studied and compared with the corresponding processes in the presence of the homogeneous Co-POM. The autoxidation process affords allylic oxidation products, the selectivity to verbenol/verbenone decreases with alkene conversion and attains 70% at 20% conversion and 40% at 46% conversion. The catalysts can be used repeatedly without loss of the activity and selectivity during several catalytic cycles. Co-oxidation of α -pinene and IBA produces selectively α -pinene epoxide with up to 94% selectivity at 96% alkene conversion. The catalysts can be regenerated by evacuation.