Theoretical correlation of substituent effects on the acidity of benzoic acids in the vapour phase with calculated HOMO eigenvalues

Abstract

Substituent effects on the gas-phase acidity of benzoic acids are shown to have a linear correlation with the substituent effects Δε_x on the HOMO eigenvalue of the corresponding anions. This calculated property also correlates with substituent effects on gas-phase acidity of phenols, and therefore seems to play a role equivalent to that of Hammett σ constants for the solution properties of the same set of substances.