NMR STUDIES OF CONFORMATIONAL EQUILIBRIA IN SUBSTITUTED ETHANES
Technical rept. no. 47
ILLINOIS UNIV AT URBANA WILLIAM A NOYES LAB
Pagination or Media Count:
Proton and fluorine magnetic resonance spectra were observed in 12 liquid polysubstituted ethanes over temperature ranges of 250 to 450 deg K. In each of these compounds, reorientations about the C-C bond are fast enough to yield high resolution nmr spectra which are averages of the three rotational isomers. The change in the proportions of the isomers with temperature is large enough for the case of some of the isomers for which J sub HF has been reported, to permit a least-squares type analysis of the averaged shifts V and coupling constants J with a high-speed digital computer. The latter evaluates the physical parameters, 3 or 5 depending upon molecular symmetry, which govern the temperature dependence of V and J. These parameters are the values of the spectral quantity in question for each of the rotamers, and the relative energies of the latter.
- Organic Chemistry