Enantioselective styrene epoxidation using the Jacobsen catalyst immobilized on functionalized SBA-15

The chiral Jacobsen complex has been immobilized by anchoring oil organofunctionalized SBA-15 Supports. Two types of functionalization agents have been tested: 3-aminopropyltrimethoxysilane and p-aminophenyltrimethoxysilane. The different materials so obtained have been checked as catalysts in the enantioselective styrene epoxidation, several reusing tests being carried Out ill Order to find Out the activity and stability of the heterogeneized systems. The best results were obtained with the catalyst prepared by anchoring oil a SBA-15 Support previously functionalized with aminophenyl groups, Since after three reaction tests this system is still active and enantioselective in the epoxidation reaction while it retains 72% of the Mn(salen) complex contained ill the raw catalyst. A Study of the catalyst stability related with the amount of oxidant and catalyst in the reaction medium is presented. The Jacobsen complex leaching was almost removed by working at both high substrate/oxidant and catalyst/substrate ratios.