Bond energy additivity and bond interactions in fluoro-halogenated hydrocarbons

Abstract

Heats of formation of fluorocarbons and fluorohalogenated hydrocarbons are re-evaluated in view of recent revisions of the standard heats of formation of aqueous hydrofluoric acid and gaseous carbon tetrafluoride. The re-evaluated data are examined according to the bond additivity and bond interaction scheme of Allen. There is a satisfactory correlation in respect of halogen-substituted methanes and fluorocarbons, but the correlation is less successful for halogenated ethanes. It is suggested that steric repulsion effects between halogen atoms attached across the central C–C bond are significant.