Cationic organomagnesium complexes as homogeneous catalysts for the ring-opening polymerization of lactones.

摘要

Polylactones are biodegradable polymers which may be used as alternatives to conventional plastics and have shown promise in novel medical applications. Industrial production of polylactones requires the use of a catalyst. The work described herein is directed toward the development of novel cationic magnesium-based lactone-polymerization catalysts. These cationic species are produced by alkide abstraction from a neutral precursor; a strategy which has seen only preliminary exploration in the context of lactone polymerization.;These catalysts are very active in the polymerization of 6-caprolactone, generating high molecular weight polymers in mere minutes under mild conditions. A preliminary study of polymerization catalysis is also reported.;The target catalyst system features a neutral phosphinimine-derivative ligand structure which was developed and produced specifically for the purpose of lactone polymerization catalysis. Target complexes were obtained by reaction of neutral alkylmagnesium precursors with protonated ligand derivatives. Syntheses and characterization of novel species are described herein.