Dj. Darensbourg et Ms. Zimmer, Copolymerization and terpolymerization of CO2 and epoxides using a solublezinc crotonate catalyst precursor, MACROMOLEC, 32(7), 1999, pp. 2137-2140
A soluble catalyst precursor derived from the reaction of zinc bis(trimethy
lsilyl)amide, Zn[N(SiMe3)(2)](2), and crotonic acid has been found to be ex
tremely active toward the copolymerization of cyclohexene oxide and carbon
dioxide with turnover frequencies approaching 35 g/g of Zn/h at 80 degrees
C. This catalyst precursor was also demonstrated to be an efficient terpoly
merization catalyst when propylene oxide or styrene oxide was added to the
cyclohexene oxide/CO2 feed. Extensive characterization of the metal complex
proved difficult, but P-31 NMR studies have shown that only 10% of the ant
icipated epoxide binding sites were available for catalysis. This suggests
that the complex has several structures at its disposal, only one of which
is conducive to copolymerization.