Computational Studies of the Dehalogenation of Aromatics

Abstract

The chemical properties affecting dehalogenation reactions occurring by homolytic bond cleavage and hydride transfer are investigated for halogenated aromatics. Gas phase bond dissociation enthalpies and standard enthalpies of formation, aqueous bond dissociation free energies and Gibbs free energies of formation, aqueous Gibbs free energies of dehalogenation, and aqueous two-electron reduction potentials are predicted for benzene and the 36 (poly)fluoro-, (poly)chloro-, and (poly)bromo- benzenes using a validated density functional protocol combined with continuum solvation calculations when appropriate. The nucleophilic aromatic substitution reactions of halogenated aromatics in aqueous solution are investigated, as is the binding of halogenated aromatics to model complexes simulating a rough Rh/Al₂O₃ catalyst. A computational methodology is presented that could be used to extend these studies to highly condensed aromatic systems.