Mechanistic Studies Employing In Situ Infrared Spectroscopy of Reactions Pertinent to Metal-Catalyzed Carbon Dioxide/Epoxide Coupling Processes

Texas A&M Research Foundation, College Station TX

Investigators

Abstract

This award by the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Prof. Donald J. Darensbourg of Texas A&M University to address the utilization of carbon dioxide in the development of improved synthetic routes for the production of polycarbonates. The current industrial production of these materials is both hazardous and expensive and involves the interfacial polycondensation of phosgene and diols. This research will examine in detail the mechanistic aspects of metal catalyzed carbon dioxide/epoxide coupling reactions employing in situ spectroscopy methods utilizing Fourier-transform infrared attenuated total reflectance (FTIR/ATR) spectroscopy. Selected processes will be investigated both in carbon dioxide swollen organic solvents and in the absence of added solvents where phase behavior is of importance. Experiments are designed to understand the various factors controlling carbon dioxide /epoxide coupling processes involving alicyclic vs aliphatic epoxides with particular emphasis on copolymer vs cyclic carbonate formation. Selected catalyst systems to be examined include those with adjacent nucleophile/epoxide binding sites and those with trans related binding sites (e.g., (salen)Cr(III)Cl). Other studies will explore the development of structural and reactivity models for the industrially prevalent double metal cyanide catalysts (DMC) used in polyether and polycarbonate synthesis. The very important fields of organometallic chemistry, catalyst design, polymer catalysis and characterization provide valuable training for graduate and undergraduate students entering either the academic or industrial work force. Furthermore, these studies heighten students' sensitivities to the roles chemists play in issues of environmental concern. Outreach programs involve high school students in research projects. This research seeks to find new, more environmentally benign ways of producing polycarbonate plastics utilizing carbon dioxide as a synthetic component.