HSAB analysis of charge transfer in the gas-phase acid-base equilibria of alkyl-substituted alcohols

A simple model to analyze charge redistribution associated with proton tran sfer (PT) reaction is derived from a classical ion transport model. The mod el is applied to the gas-phase acid-base ecluilibria of alkyl alcohols. Pro ton transfer is simulated as the motion of a charged particle in an applied external potential defined by the chemical environment of the proton, and represented by the difference in proton affinity (PA) of the conjugated bas es RO- and CH3O-; the latter is taken as reference. The electronic chemical potential of transfer accounts for both the amount and direction of charge transfer (CT). The relative acidity for a short series of alkyl alcohols i s determined by the difference in proton affinity (Delta PA = PA(RO-) - PA( CH3O-)) of the conjugated bases. The predicted charge transfer is in agreem ent with the CT pattern obtained from the group hardness and electronegativ ity analysis.