ORGN 43 |
| Physical-organic chemistry has had a long connection with carbocations. Solvolysis kinetics was a key method for their study. In the 60's, it became possible to prepare stable solutions of some carbocations and to obtain their NMR spectra. Rapid degenerate rearrangements produced line-broadening which, through computer simulation, yielded rate constants and barriers. With extremely rapid rates, sharp averaged peaks are obtained. Isotopes perturb these systems, breaking the degeneracy and induce splittings which yield equilibrium isotope effects. When there is no barrier and a single bridged ion, as in the case of norbornyl cation (called nonclassical by Winstein), there is no splitting. Theoretical calculations have been applied to many questions concerning carbocations. Theory and experiment yield complementary information. Theory is not limited to predicting structures and energies, but can also calculate chemical shifts and spin coupling constants. Equilibrium isotope effects can be predicted to compare with experimental results. |
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James Flack Norris Award in Physical Organic Chemistry
1:00 PM-5:00 PM, Sunday, 13 March 2005 Convention Center -- Ballroom 20 C-D, Oral
Division of Organic Chemistry |