Olefin epoxidation by dioxiranes and percarboxylic acids: an analysis of activation energies calculated by a density functional method

The activity of dioxiranes, R2CO2, and percarboxylic acids, RCO(O-2)H, in o lefin epoxidation reactions can be rationalized by a frontier orbital inter action. Barrier heights of these oxygen transfer reactions, as calculated b y a density functional method, depend linearly on the energy of the olefin HOMO orbital pi (C-C) and of the peroxide LUMO orbital sigma*(O-O). Activat ion barriers can be predicted from linear relationships with the proton aff inity of a dioxirane (as measured by the hydrogen fluoride association ener gy) or the pK(n) value of a percarboxylic acid. Copyright (C) 2001 John Wil ey & Sons, Ltd.