AB Initio Calculations on Eliminations and Proton Transfers

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With the support of the Organic Dynamics Program, Professor William H. Saunders, Jr., of the Department of Chemistry at the University of Rochester, is carrying out quantum chemical calculations on elimination and proton transfer reactions. Calculations on fluorine-substituted carbanions permit the assessment of the role of negative ion hyperconjugation, and studies of elimination reactions of fluorohydrocarbons address the borderline between E1cb and E2 reaction pathways. Factors governing the orientation and stereochemistry of concerted elimination reactions are examined through consideration of charge distributions, isotope effects, and ion pairing. Particular attention is placed on developing an understanding of the syn-anti dichotomy, wherein cis olefins are produced by anti elimination but trans olefins are produced by syn elimination. Among the superficially simplest chemical reactions are those involving the transfer of a single positively-charged hydrogen atom (a proton) from one place in a molecule to another. Despite the apparent simplicity of such reactions, however, experimental results indicate appreciable complexity. Through the application of calculational techniques and with the support of the Organic Dynamics Program, Professor William H. Saunders, Jr., of the Department of Chemistry at the University of Rochester, is exploring the fundamental aspects of proton transfer reactions. His studies also extend to the analysis of reactions initiated by the loss of a proton, focusing in particular on whether the overall reaction path for such reactions involves simultaneous elimination of an additional group or if such elimination occurs subsequently to the initial proton loss. These issues are central to an extraordinarily wide variety of chemical reactions, and Professor Saunders' studies are leading to a fundamental understanding of the factors controlling them.