Cobaltcarbonyl Complexes — Tunable Catalysts for the Carbonylation of Epoxides

Abstract

AbstractPoly(hydroxyalkanoates) establish an important family of thermoplastic materials which can be synthesized from epoxides and CO either directly through a recently discovered, alternating copolymerization reaction or via a lactone intermediate. A mixture of Co(acac)3 and Et3Al is a known but poorly understood catalyst system for the formation of low molecular weight PHB (polyhydroxybutyrate) from propylene oxide and CO. We investigated this catalyst system by online ATR‐IR spectroscopy and found it to produce mixtures of β‐butyrolactone (primary product) and polyester. In contrast to this less selective mixture we present here a new catalyst comprising Co2(CO)8 / R3Al for the highly chemo‐ and regioselective β‐butyrolactone formation from propylene oxide and carbon monoxide.