Kelly, Kelmara K. (2009-05). Novel Isotope Effects and Organic Reaction Mechanisms. Doctoral Dissertation. Thesis uri icon

abstract

  • A variety of organic reactions provide experimental observations that are not explained by current models of reactivity and selectivity. This dissertation describes a combination of experimental and theoretical studies of such reactions. In the ene reaction of singlet oxygen with tetramethylene, it is found that standard statistical rate theories fail to account for the observed kinetic isotope effects, particularly with regard to their broad temperature independence. Dynamics trajectories are found to account for the observed isotope effects. In the dimerization of cyclopentadiene, novel "dynamic" isotope effects are observed on the 13C distribution in the product, and a method for the prediction of these isotope effects is developed here. In the cycloaddition of diazomethane with dimethylfulvene, it is found that the current model of the mechanism as a [6 + 4] cycloaddition is incorrect, and a new mechanism is proposed. Isotope effects have been measured for the recently reported unusual "on water" quadricyclane cycloadditions, and the implications of these observations toward the mechanism are discussed.
  • A variety of organic reactions provide experimental observations that are not
    explained by current models of reactivity and selectivity. This dissertation describes a
    combination of experimental and theoretical studies of such reactions. In the ene
    reaction of singlet oxygen with tetramethylene, it is found that standard statistical rate
    theories fail to account for the observed kinetic isotope effects, particularly with regard
    to their broad temperature independence. Dynamics trajectories are found to account for
    the observed isotope effects. In the dimerization of cyclopentadiene, novel "dynamic"
    isotope effects are observed on the 13C distribution in the product, and a method for the
    prediction of these isotope effects is developed here. In the cycloaddition of
    diazomethane with dimethylfulvene, it is found that the current model of the mechanism
    as a [6 + 4] cycloaddition is incorrect, and a new mechanism is proposed. Isotope
    effects have been measured for the recently reported unusual "on water" quadricyclane
    cycloadditions, and the implications of these observations toward the mechanism are
    discussed.

publication date

  • May 2009