KINETIC-STUDIES ON THE PYRAMIDAL INVERSION OF OPTICALLY-ACTIVE SELENONIUM IMIDES

Kinetic studies were carried out on the thermal epimerization by pyram idal inversion of optically active (S)(-)(Se)- and propylphenyl)seleno nium-N-toluene-4'-sulphonimides (1). The first-order rate constants fo r the pyramidal inversion of (S)-(-)(Se)-1 and (R)-(+)(Se)-1 were dete rmined and the activation enthalpies and entropies were calculated. A fairly large difference was found in the activation parameters between optically active (S)-(-)(Se)-1 and (R)-(+)(Se)-1, i.e. a large negati ve activation entropy was obtained in the case of (R)-(+)(Se)-1.