Heterogenization of Homogeneous Systems

The quest for separation and recycling has always been a key issue in homogeneous catalysis in general. This is why methods have been devised to anchor the 

The use of commercial polymers to immobihze homogeneous catalytic species dates back to the early 1970s. Initial supports were in most cases commercial ion 

Using cyclohexene as a model substrate and TBHP as the oxidant, Cu, Mn, Fe, Ru and Ti have all been shown to be catalytically active when supported on FBI. PBI.Cu, PBI.Mn and PBFFe are all potentially useful allylic oxidation catalysts PBI.Ru offers an opportunity in dihydroxylation, and perhaps not surprisingly, PBI.Ti shows significant selectivity towards epoxidation.  

Attempts to switch to more appealing oxidants, such as hydrogen peroxide, by immobilizing simple tungstate anions on poly(methacrylate)-based aminophospho-rilated resins to carry out epoxidation were only moderately successful because of significant metal leaching into solution with consequent loss of activity.  

Methyltrioxorhenium (MTO) has perhaps been the most successful homogeneous catalyst for the epoxidation of simple olefins with hydrogen peroxide, however, attempts to modify the catalyst to achieve enantioselective epoxidation or anchoring to a solid support have met with only moderate success, probably because 

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