Rate of chair-to-chair interconversion of cyclohexane-d12 in its neat plastic crystalline phase

Abstract

The exchange rate of axial and equatorial deuterons by ring interconversion in neat plastic crystalline cyclohexane-d 12 has been measured directly for the first time. The rate constant k and the associated free energy of activation ΔG for this process at the NMR coalescence temperature (222 K, in a 7.04-T static magnetic field) was determined and compared with existing liquid-state and gas-phase values. The NMR technique which allows the measurements to be made is a deuterium Bloch decay experiment with magic angle spinning (MAS)