Tailoring the Window Sizes to Control the Local Concentration and Activity of (salen)Co Catalysts in Plugged Nanochannels of SBA-15 Materials...

摘要

The exploitation of micro-channel reactors for rapid, facile organic synthesis is a subject of intense investigation. Among these, chiral (salen)metal complexes catalyze many asymmetric transformations of the hydrolysis of terminal epoxides through hydrolytic kinetic resolution (HKR) into single enantiomers. Attempts to increase the local concentration of these metal complexes by some type of confinement have led to the development of "ship-in-a-bottle synthesis" of metal compounds in which catalyst precursors are diffused into the micropore structure of zeolites. The resulting catalysts display the beneficial properties of homogeneous catalysts, namely high selectivity and activity, and of heterogeneous catalysts through facile recovery and reuse. However, the main challenge of host-guest catalysis is the decrease in activity owing to the limits of mass transfer relating to the small window sizes (Figure 1).