Co-Salen Complexes

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Technology  hristopher W. Jones, Michael J. Holbach, Marcus Weck, and Xiaolai Zheng from the School of Chemistry and Biochemistry at Georgia Tech have synthesized a novel polymer-supported salen ligand that is recyclable and reusable. The polymers, poly(norbornene) and poly(styrene), can be metallated with cobalt to yield a co-salen complex that is as active and effective as its non-supported analogous. The complex can also be reused with almost identical reactivity and enantioselectivity, given proper procedure of isolation and reactivation. The polymeric cobalt complexes were successfully used as supported catalysts for hydrolytic kinetic resolution (HKR) of epoxides as well as asymmetric epoxidation of olefins. The complexes showed catalytic activity and selectivity comparative to that of the original Jacobsen catalysts. Cobalt-based copolymers were found to be more active and selective than their homopolymer analogues. The catalysts demonstrated possibility of easy metal removal from the product as the catalysts were easily removed from the reaction mixtures and with proper recycling, the catalyst retained activity and selectivity for further use.  Advantages Recyclability Retention of activity and selectivity Ease of separation from reaction product Cost-effective solution