<p> Several ketones in the bicyclo{2.2.1.}heptane system, many of them previously unknown, have been prepared and characterized; these included monoketones, enones and diones. They are listed in Fig. II-1.</p> <p> The conformations of norbornane-2,5-dione (27) and 3,3-dimethyl-norbornane-2,5-dione (26) have been carefully examined by nuclear magnetic resonance spectroscopy. These compounds have been found to exist in two different synchro twist conformations.^76</p> <p> The stereochemistry of base-catalyzed protium-deuterium exchange of the diones 25, 26 and 27 has been examined and has been found to be similar to the stereochemistry of exchange in monoketones previously observed in these systems, viz exo exchange is considerably more rapid than endo exchange.</p> <p> The rates of NaOD-catalyzed protium-deuterium exchange of the ketones, enones and diones have been measured in 60 % dioxane-D2O at 25°. The rate data is shown in Table II-4. Kinetic analysis showed that these rate constants represent the true reactivity of the hydrogen for which the rate of exchange was measured.</p> <p> A study of the 13C chemical shift of highly substituted bicyclo{2.2.1.}heptanes has been undertaken, and also a study of the 13C-H coupling constants of many of these compounds has been made. The results are listed in Tables II-6 and II-8. They suggest that there are no unusual hybridization effects at the enolizable carbon in the diones and enones under study.</p> <p> The rate data, together with some literature data, shows that hybridization effects, torsional effects, conformational effects and strain effects are of minor importance in the exchange reactions. The rate acceleration observed in the dione systems is almost entirely accountable by an inductive effect of the second carbonyl group, with very little homoconjugative participation.</p> <p> The kinetic results suggest that an enol is the intermediate in the enolization reaction, and that the transition state occurs relatively early along the reaction coordinate.</p> / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/20361 |
| Date | 01 1900 |
| Creators | Taillefer, Roland J. |
| Contributors | Werstiuk, N. H., Chemistry |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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