RELATIONSHIP BETWEEN BOND-DISSOCIATION ENERGIES AND ACTIVATION-ENERGIES FOR BOND SCISSION REACTIONS

Bond dissociation energies are frequently derived from values of the h igh pressure activation energy for bond scission reactions. The value derived depends on the transition state structure chosen for the react ion. We consider several models of the transition state and show that the variation in derived BDE values can be quite substantial, 3 to 6 k cal/mol at the high temperatures of pyrolysis kinetics. Application of the restricted Gorin model of the transition state results in BDE val ues in good agreement with current thermochemistry, while the other mo dels tested result in lower to much lower values. (C) 1994 John Wiley and Sons, Inc.