Molecular modelling studies on the reactions of fluoroalkenes with sulfur trioxide

Abstract

The structures, molecular energies and electronic properties of a series of substituted fluoroalkenes and the corresponding alkane sultones, derived from the addition of sulfur trioxide to the double bond, have been explored using a combination of molecular modelling and theoretical calculations. Both the calculated charge distributions at carbon and the calculated enthalpies of the addition process show a good correlation with the observed selectivity of electrophilic attack by the sulfur atom of sulfur trioxide, especially for unsymmetrical alkenes where there are two possible sites of addition. Mechanistically, the reactions of ethene and tetrafluoroethene with sulfur trioxide proceed via formation of stable π-complexes to give a transition state in the former case which is predicted to have a comparable energy to that found experimentally for the related reaction of octadec-1-ene.