Direct oxidation of benzene by electron transfer in a multi-functionalized chelate resin system

Abstract

A polystyrene-based chelate resin, functionalized by tridentate iminodiacetate (ida) moieties, can easily immobilize various components by ion exchange or co-ordination. A multi-functionalized chelate resin immobilized with both ultrafine platinum particles and Fe^II ions has been prepared successfully by co-ordinating Fe^II ions to ida moieties after supporting ultrafine platinum particles. Electron transfer from the Fe^II ions to oxygen produced Fe^III ions and activated oxygen in the system, while the Fe^III ions were reduced again to Fe^II ions by molecular hydrogen via the platinum particles. The activation of oxygen molecules and/or a C–H bond of benzene are essential to the direct oxidation of benzene. Thus, benzene has been oxidized directly by activated oxygen to produce p-benzoquinone as the main product, indicating that the multi-functionalized chelate resin works like a dioxygenase enzyme. The oxidizing species for benzene was concluded to be the Fe^II–dioxo complex, the co-ordinating oxygen of which is activated.