Mechanistic Studies of Organic Reactivity

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Professor Jeehiun Katherine Lee of the Department of Chemistry at Rutgers University will utilize funding provided by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division to explore organic reactivity and mechanism. One major focus will be on the complementary polarities of reactants in chemical reactions. This is commonly referred to as nucleophilicity ("seeking nuclei") or electrophilicity ("seeking electrons"). The nucleophilicity and electrophilicity of diverse reactants will be examined in the gas phase, with the ultimate goal of creating a scale to better understand fundamental reactivity. A second focus will be on reactions catalyzed by N-heterocyclic carbenes (NHCs). NHCs are novel organic substances, which have been shown to act as catalysts for a broad range of important synthetic reactions. Mechanisms for these reactions are poorly understood. In both aims, chemical reactions will be studied through a combination of computational models and experiments. Experimental studies are carried out in the gas phase, using a mass spectrometer. The absence of solvent allows for inherent reactivity to be revealed. This project has the potential to establish reactivity patterns for a wide range of organic species and improve the utility of NHCs as catalysts in chemical synthesis. Improved synthetic methods in turn impact many areas of chemistry, including making pharmaceuticals and other useful chemicals. These fundamental mechanistic studies also provide educational opportunities for both undergraduate and graduate scientists. The project provides mentoring and training for groups underrepresented in science as well.Gas phase experimental (mass spectrometric) and computational (quantum mechanical) methods are used to interrogate the properties and reactivities of species of organochemical significance. Specifically, a number of hypotheses centered on nucleophilicity, electrophilicity, reactivity, and catalysis will be tested. One objective is the development of a gas-phase scale for nucleophilicity and electrophilicity of substrates (including N-heterocyclic carbenes (NHCs)); the second objective is to gain insight into the mechanism by which NHCs catalyze synthetically important reactions. These studies will ultimately aid in the development of processes involving hydrogen activation, organocatalysis and synthesis. The work will have societal impact in terms of the education of undergraduate and graduate students, including students from underrepresented groups, and publication of research that increases fundamental chemical understanding.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.