Instantaneous bond dissociation energies in hydrocarbons

Abstract

An attempt is made to derive instantaneous bond dissociation energies of hydrocarbons from experimentally determined bond dissociation energies taking into account energy changes involved in rehybridisation during dissociation. Heats of atomisation and strain energies obtained from the values so calculated, corrected by structure factors in branched hydrocarbons and by 1,4-gauche interactions, agree well with experimental values and lead to a heat of formation of ‘valence state’ carbon of about 39 kcal. mole^–1. The structure factors may be related to barriers to internal rotation. Heats of formation and resonance energies of some free radicals are also derived.