Enthalpies of transfer for conjugate-base anions of weak acids in acetonitrile–methanol mixtures. An approach to molecular thermodynamics of ionization for weak acids in the aqueous phase

Abstract

A group-dependent correlation is observed between the Gibbs energies of ionization for weak acids in the aqueous phase, ΔG₀, and the specific interaction enthalpies for the conjugate-base anions of weak acids and for uncharged amines, Δ_tH_SI(AN → MeOH). A group-independent correlation is observed between the entropies of ionization for weak acids in the aqueous phase, ΔS_o, and the specific interaction enthalpies for the conjugate bases. The weak acid ionization in the aqueous phases is rationalized thermodynamically by the low endoergicity of ionization and entropy-controlled substituent effects.