Donor–acceptor and polarity parameters for hydrogen bonding solvents

Abstract

The acceptor parameters E_A′ and C_A′, as well as the unified solvation model solvent polarity parameters S′ have been determined for 18 hydrogen bonding solvents enabling resolution of spectral shifts into specific and non-specific components. Equations are given which permit calculation of the E_A and C_A acceptor parameters for 77 substituted phenols. Alcohols are amphoteric solvents. This study also reports the donor parameters E_B and C_B to permit the calculation of the specific interaction for alcohols reacting as bases. Some of the well-known scales of solvent polarity and hydrogen bond acidity are examined and the claims made for the absence of specific or non-specific contributions in the scales evaluated. The ability of the unified solvation model to correlate a diverse set of solvation parameters shows the advantage of treating specific and non-specific solvation separately.