James W. O'Neil

The activation enthalpy and entropy for the inversion-rotation process in dibenzylmethylamine

Abstract The temperature dependence of the PMR spectrum of the diastereotopic benzyl protons of dibenzylmethylamine has provided the activation parameters for nitrogen inversion. A method is described to account for the substantial variation in T 2 of the benzyl protons resonances as a function of temperature in the intermediate exchange region.

Activation parameters for conformational isomerism in an N-acetylpyrrolidine by total nuclear magnetic resonance line shape analysis and direct thermal stereomutation

Additional experimental evidence supporting total n.m.r. line shape analysis for obtaining activation parameters results from a comparison of rate data derived from the direct equilibration at low temperatures of a conformationally pure rotamer of (I) and rate data from a total n.m.r. line shape analysis at higher temperatures.

Activation parameters for chair–twist equilibration in 3,3,6,6-tetramethyl-1,2,4,5-tetrathian by direct thermal stereomutation and total nuclear magnetic resonance line-shape analysis

Activation parameters (Ea, ΔG‡, ΔH‡, ΔS‡) for the chair–twist process in 3,3,6,6-tetramethyl-1,2,4,5-tetrathian have been obtained from the direct equilibration of the pure twist conformer and from matching experimental n.m.r. spectra with theoretical spectra over an appropriate temperature range.