A quantitative interpretation of phase effects in anaesthesia

Abstract

The anaesthetic potencies of 45 halogenated hydrocarbons have been fitted to a simple phase distribution model. The model approximates the activity coefficient at infinite dilution as a function of the dominant intermolecular interactions in the given phase. For a series of halogenated hydrocarbons, this function reduces to an empiric balance between the compounds' van der Waal and hydrogen bond donor properties. The strength of the hydrogen bond interaction of CHF3 with the anaesthetic phase is estimated to be 1.5 ± 0.2 kcal, assuming a 1:1 interaction. This is in agreement with theoretical and observed estimates of weak CH … O bonding. It is suggested that theoretical estimates of hydrogen bond donor and acceptor properties in compounds may have a general role to play in evaluating nonspecific biological processes.