Concertedness and E2 elimination reactions: prediction of transition state position and reaction rates using two-dimensional reaction surfaces based on quadratic and quartic approximations

Abstract

An analytical expression for the two-dimensional reaction surface appropriate for discussing a concerted reaction has been derived for the quartic approximation to a reaction coordinate, and shown to be consistent with Marcus theory. By analysis of literature data for SN1 solvolyses and carbanion formation we have been able to reproduce the qualitative behavior of eliminations involving tBuBr, iPrBr, and EtBr in EtOH/EtO−, and to predict the rates of these reactions within the uncertainties of the input data. Keywords: concerted reactions, Marcus theory, eliminations, reaction surfaces.