<p> It has been shown that the hydroxy compounds la-4a possess triplet states which
are substantially shorter-lived than those of their methoxy analogs (lb-4b). In each case
the efficient quenching of the excited carbonyl triplet state has been attributed to
intramolecular phenolic hydrogen abstraction. Evidence for this is found in the detection
of biradical species generated from triplet decay, primary hydrogen-deuterium kinetic
isotope effects and thermodynamic parameters which support both atom transfer
(enthalpy) and high degrees of order (entropy) in the transition state necessary for the
proposed abstraction process. The difference in triplet lifetimes (16 ns to 1135 ns) is due
almost exclusively to varying degrees of difficulty in obtaining a transition state geometry
in which the phenoxy hydrogen is properly lined up for intramolecular hydrogen
abstraction. </p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/19243 |
| Date | 06 1900 |
| Creators | St. Pierre, Michael |
| Contributors | Leigh, William, Chemistry |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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