rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Dynamic Effects of Alkoxy Radicals
  name:
    name part: Alvi, Scheherzad
    role:
      role term: creator
    role:
      role term: author.
  name:
    name part: Singleton, Daniel
    role:
      role term: thesis advisor.
  name:
    name part: Texas A&M University
    role:
      role term: degree granting institution.
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: txu
    date issued: 2023
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: remote
    extent: 1 online resource.
  abstract: Reaction mechanisms are generally probed by looking at the energetics of observable intermediates and the transition states that have observable effects on rates or selectivity. Mechanisms are complex, however, and there are often many transition states and intermediates hidden from observations. We described here how hidden mechanistic steps can be probed by observing their effect on a later product selectivity. This is possible because molecules that pass through a high energy-barrier retain their excess energy for a short time. It only takes a few dozen femtoseconds to pass into the area of a subsequent intermediate. This is short compared to the picoseconds it takes for energy to dissipate out to the environment. In this way, the intermediates possess excess energy that is neither thermally equilibrated nor initially statistically distributed within the molecule. We have observed this effect in reactions of short-lived alkoxy radical intermediates. Depending on how a methylcyclobutoxy radical is chemically generated, the kinetic isotope effects (KIE) for next C-C bond cleavage step changes. We observed KIE in-turn allows us to read-out the amount of excess energy the alkoxy radical gained during its generation. This provides a new kind of mechanistic probe. In recent years, many new methods have been developed for oxidation of alcohols that have shown alkoxy radicals as the key intermediates. These methodologies often involve steps like electron transfer or electronic excitation that cannot be studied by ordinary mechanistic probes. Herein, the process of energy read-out can be utilized to point out crucial steps and investigate hidden transition states. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/198542
  note: by Scheherzad Alvi.
  note: "Major Subject: Chemistry"
  note: Includes vita.
  note: Doctor of Philosophy Texas A&M University 2022 https://hdl.handle.net/1969.1/198542
  note: Includes bibliographical references.
  note: Text (Dissertation)
  subject:
    topic: Major Chemistry
  subject:
    topic: Reaction mechanisms
  subject:
    topic: Kinetic Isotope Effects
  subject:
    topic: Proton Coupled Electron Transfer
  identifier: https://hdl.handle.net/1969.1/198542
  record info:
    record content source: TXA
    record creation date: 240924
    record change date: 20250326141430.6
    record identifier: in00005621371
    language of cataloging:
      language term: eng