RESTRICTED ROTATION INVOLVING THE TETRAHEDRAL CARBON .26. CERTAINTIES AND UNCERTAINTIES INVOLVED IN THE RATES OF EXCHANGE AMONG 3 SITES AS OBTAINED BY TOTAL LINE-SHAPE ANALYSES OF H-1-NMR SPECTRA - CASE OF METHYLENE SIGNALS

Benzyl methylene signals, which split into an AB quartet and a singlet and show temperature dependence, are obtained at various temperatures and are simulated with the use of two independent rates of rotation. Certain limitations of accuracy are found in this method. The uncertainty becomes less if additional data are provided from other sources, but never becomes negligible. Contribution of the slower process is found difficult to detect especially when the population involved in the process are the less.