Pericyclic Transition Structures

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In this project in the Organic Dynamics Program, Professor Henry J. Shine will study "Pericyclic Transition Structures" in the Chemistry Department at Texas Tech University. Professor Shine is collaborating with Professor William H. Saunders in the Chemistry Department at the University of Rochester. In this study heavy atom kinetic isotope effects with specifically labelled substrates are being measured and bond order modeling calculations are being carried out in order to define the transition structures of reactions that are known to be pericyclic. Heavy atom (carbon, nitrogen, and, oxygen) kinetic isotope effects (KIE) and bond order modeling calculations are being made in order to define the transition structures of several pericyclic reactions. Reactions being studied are the aromatic Claisen rearrangement (allyl phenyl ether), the benzidine rearrangement (hydrazobenzene), and the aliphatic Claisen rearrangement (allyl vinyl ether and two of its derivatives). The objective in the aromatic Claisen rearrangement and in the benzidine rearrangement is to use them to probe along the reaction coordinate for coupled motion of carbon atoms not directly involved in bond breaking and making. In the aliphatic Claisen rearrangements the objective is to define their transition structures and synchronicities, over which controversy has arisen from theoretical treatments. Modeling calculations will be made to fit KIE to bond orders and, hence, to optimized transition structures.