Organic reactions are systematically examined experimentally and theoretically to
determine the role dynamics plays in the outcome of the reaction. It is shown that
trajectory studies are of vital importance in understanding reactions influenced by
dynamical motion. This dissertation discusses how a combination of kinetic isotope
effects, theoretical calculations, and quasiclassical dynamics trajectories aid in the
understanding of the solvolysis of p-tolyldiazonium cation in water, the cycloadditions
of cyclopentadiene with diphenylketene and dichloroketene, and the cycloaddition of 2-
methyl-2-butene with dichloroketene.
In the solvolysis of p-tolyldiazonium cation, significant 13C kinetic isotope effects
are qualitatively consistent with a transition state leading to formation of an aryl cation,
but on a quantitative basis, the isotope effects are not adequately accounted for by simple
SN1 heterolysis to the aryl cation. The best predictions of the 13C isotope effects for the
heterolytic process arise from transition structures solvated by clusters of water
molecules. Dynamic trajectories starting from these transition structures afford products very slowly. The nucleophilic displacement process for aryldiazonium ions in water is
determined to be at the boundary of the SN2Ar and SN1 mechanisms.
The reaction of cyclopentadiene with diphenylketene affords both [4 + 2] and [2 +
2] cycloadducts directly. This is surprising. There is only one low-energy transition
structure for adduct formation. Investigation of this reaction indicates that quasiclassical
trajectories started from a single transition structure afford both [4 + 2] and [2 + 2]
products. Overall, an understanding of the products, rates, selectivities, isotope effects,
and mechanism in these reactions requires the explicit consideration of dynamic
trajectories.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4877 |
| Date | 25 April 2007 |
| Creators | Ussing, Bryson Richard |
| Contributors | Singleton, Daniel A |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 3300124 bytes, electronic, application/pdf, born digital |
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