CHED 859 |
| Nicholas D. Penner and Jerry R. Mohrig. Department of Chemistry, Carleton College, 1 North College St., Northfield, MN 55057 |
| In a continuing effort to understand the stereochemistry and mechanisms of elimination reactions, we have studied the rates of tert-butyl 3-(3-trifluoromethylphenoxy)thiobutanoate and the analogous ethyl ketone with NaOH in 5:1 EtOH/H2O. Our earlier rate studies in a 3:1 EtOH/H2O solvent showed kketone/kthioester ≈ 4 in spite of the 1000-fold difference in their acidities—indicating that the elimination takes place near the E1-cB interface. The ethyl ketone is too insoluble in the 3:1 mixture to conduct stereochemical studies, so 5:1 EtOH/H2O was used. Due to this, it was necessary to obtain kinetic data in 5:1 EtOH/H2O, to ensure that the solvent change did not substantially affect the reaction pathway. We have determined that the rate constant for the thioester is only slightly larger in 5:1 EtOH/H2O, suggesting there is little mechanistic difference. Data from the elimination of the ketone substrate will also be presented. |
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Undergraduate Research Poster Session: Organic Chemistry
2:00 PM-4:00 PM, Monday, March 29, 2004 Anaheim Convention Center -- Hall A, Poster
Division of Chemical Education |