George Lynn Cross Research Professor
B.S., 1969, Stony Brook University, New York
Ph.D., 1972, University of Texas, Austin
Postdoc, 1972-1973, Brandeis University, Waltham, Massachusetts
organic, inorganic and organometallic chemistry, development of new organic reactions, transition metal catalysts, computational reaction modeling, chemicals and fuels from renewable resources
Catalytic Deoxygenation of Renewable Alcohols and Polyols to Chemicals and Fuels
The most abundant of renewable resources, e.g. cellulose and plant oils, are highly oxygenated, so their conversion to useful chemicals or fuels often requires partial/complete oxygen removal/replacement. Our overall objective is to develop new catalytic reactions for the removal/refunctionalization of alcohols and polyols to produce value-added products. Our recent work has lead to: 1. new catalysts and reagents for deoxydehydration of glycols (DODH, Scheme) with oxo-rhenium (O=ReL) and cheaper oxo-vanadium (O=VL) catalysts; 2. novel Re- catalyzed reductive coupling (RC) reactions of activated alcohols via free-radicals; 3. efficient Re-promoted radical additions of alcohols to alkenes; and 4. insights into the mechanism of these reactions through experimental and DFT computational modeling of the reaction pathways. We are now seeking to: 1. design and prepare new earth-abundant TM compounds to facilitate the above deoxygenation reactions; 2. develop new more general reductive C-C bond-forming reactions; 3. to establish catalyst structure/reactivity relationships and reaction mechanisms that identify key intermediates and transition states through a combined experimental and computational molecular modeling approach.
Activation and Conversion of Nitrous Oxide to Benign or Useful Products (with I. Sharma, Y. Shao)
Nitrous oxide (N2O) is an important and potent greenhouse gas, emitted predominantly and increasingly by biological sources and from diesel vehicle exhaust. Although N2O is thermodynamically unstable relative to its constituents, N2 + O2, and is a potentially strong oxidant, its uncatalyzed reactions are hampered by high activation barriers. The ability of transition metal compounds to promote reactions of N2O has been shown, e.g. the multi-copper enzyme N2O-reductase, but the diversity and generality of N2O reactions, catalyst structure-activity relationships, and mechanistic understanding are all largely lacking. To address these knowledge gaps, our goal is to investigate the selective functionalization of molecules by N2O, incorporating either or both of its atoms into high value reaction products, including alkenes, alcohols and heterocycles used in polymers, petrochemicals and pharmaceuticals. More specifically, we seek to identify the essential chemical features of transition metal compounds that can bind and activate nitrous oxide to enable its capture and catalytic conversion to value- added chemicals. Through a combined DFT computational and experimental approach we are now exploring the potential for: 1. catalytic oxidation of saturated hydrocarbons by N2O to produce alcohols and alkenes; 2. N2O cycloaddition reactions with unsaturated hydrocarbons for the synthesis of valuable heterocycles and diazo ketones; and 3. N2O reactions with dipolar reagents and catalysts.
Awards & Honors
George Lynn Cross Research Professor, 1993, University of Oklahoma
Regents' Award for Superior Teaching, 1990, University of Oklahoma
Regents' Award for Superior Research & Creative Activity/Scholarly Activity, 1989, University of Oklahoma