Silica immobilized salicylaldimine Cu(II) and Co(II) complexes as catalysts in cyclohexene oxidation: A comparative study of support effects

Unsubstituted and tertiary-butyl substituted salicylaldimine complexes of Cu(II) and Co(II) immobilized on silica supports (MCM-41, SBA-15 and Davisil 710) were tested as catalysts for cyclohexene oxidation using hydrogen peroxide as an oxidant under an oxygen atmosphere. The effect of the nature of the salicylaldimine ligand and the type of support were investigated. Allylic species were isolated as the major products with cyclohexene–epoxide produced as a by-product in only some instances. Product selectivity was found to be greatly influenced by the nature of the support material.

Graphical abstractSalicylaldimine complexes of Cu(II) and Co(II) immobilized on mesoporous silica were found to be active catalysts in the liquid phase oxidation of cyclohexene. All catalysts show high selectivity to allylic oxidation products with 2-cyclohexen-1-ol and 2-cyclohexen-1-one being produced in large amounts.Figure optionsDownload full-size imageDownload as PowerPoint slide