CHED 815 |
| Andrew J. Wild and Jerry R. Mohrig. Department of Chemistry, Carleton College, 300 North College St., Northfield, MN 55057 |
| In order to understand the electronic factors influencing the stereochemistry of base-catalyzed 1,2-elimination reactions, we have studied tert-butyl 3-trimethylacetoxythiobutanoate and the analogous ester with KOH in 3:1 EtOH/H2O. The research incorporates the use of 2H NMR and stereospecifically-deuterated substrates to determine the amount of syn elimination. Our previous work suggested that this may be related to the pKa of the leaving group’s conjugate acid. However, tert-butyl 3-acetoxythiobutanoate and the analogous ester gave disproportionate amounts of syn elimination. In order to ascertain if a competing intramolecular pathway accounts for the excess syn elimination for the acetoxy substrates, we synthesized and studied the analogous trimethylacetoxy substrates. We have determined that substantially lower syn elimination occurs with tert-butyl 3-trimethylacetoxythiobutanoate and the analogous ester, suggesting that the intramolecular hypothesis is correct for the acetoxy substrates. Moreover, this study confirms our working hypothesis that the leaving group ability affects the amount of syn 1,2-elimination. |
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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 |