The fundamentally interesting and challenging chemistry associated with carbon dioxide, coupled with its high potential as a source of chemical carbon, provides adequate justification for comprehensive investigations in this area. In our research program we have attempted to establish a clearer mechanistic view of carbon-hydrogen, carbon-carbon, and carbon-oxygen bond forming processes resulting from carbon dioxide insertion into M-H, M-C, and M-O bonds.
Relevant to the latter process our research has addressed the utilization of carbon dioxide in the development of improved synthetic routes for the production of polycarbonates. The hazardous and expensive production process currently in place industrially for these materials involves the interfacial polycondensation of phosgene and diols, accentuates the need for these studies. Although we and others have made significant advances in the synthesis of these useful thermoplastics from carbon dioxide and epoxides much of the fundamental knowledge concerning the reaction kinetics of these processes is lacking, due in part to the practical challenges associated with sampling and analyzing systems at elevated temperatures and pressures. This information is needed for making this process applicable to the synthesis of a variety of copolymers possessing a range of properties and uses. Our studies are examining in detail the mechanistic aspects of metal catalyzed carbon dioxide/epoxide coupling reactions employing in situ spectroscopy methods. For this purpose Fourier-transform infrared attenuated total refluctance (FTIR/ATR) spectroscopy is being utilized. Other related investigations involve the development of structural and reactivity models for the industrially prevalent double metal cyanide catalysts(DMC) used in polyethers and polycarbonate synthesis from epoxides or CO2/epoxides, respectively.
Darensbourg, D. J.; Yeung, A. D.; Wei, S.-H. Base Initiated Depolymerization of Polycarbonates to Epoxide and Carbon Dioxide Co-monomers: A Computational Study. Green Chem. 2013, 15, 1578-1583.
Wu, G.P.; Darensbourg, D. J.; Lu, X.-B. Tandem Metal-Coordination Copolymerization and Organocatalytic Ring-Opening Polymerization via Water To Synthesize Diblock Copolymers of Styrene Oxide/CO2 and Lactide. J. Am. Chem. Soc. 2012, 134, 17739-17745.
Darensbourg, D. J.; Wilson, S. J. What's New with CO2? Recent Advances in its Copolymerization with Oxiranes. Green Chem. 2012, 14, 2665-2671.
Darensbourg, D. J.; Wei, S.-H. Depolymerization of Polycarbonates Derived from Carbon Dioxide and Epoxides to Provide Cyclic Carbonates — A Kinetic Study. Macromolecules 2012, 45, 5916-5922.
Wu, G.-P.; Wei, S.-H.; Ren, W.-M.; Lu, X.-B.; Xu, T.-Q.; Darensbourg, D. J. Perfectly Alternating Copolymerization of CO2 and Epichlorohydrin Using Cobalt(III)-based Catalyst Systems. J. Am. Chem. Soc. 2011, 133, 15191-15199.
Darensbourg, D. J.; Wilson, S. J. The Synthesis of Poly(indene carbonate) from Indene Oxide and Carbon Dioxide — A Polycarbonate with a Rigid Backbone. J. Am. Chem. Soc. 2011, 133, 18610-18613.