Medium effects on protonation equilibria in ethylene glycol for some t-butyl-substituted phenols and nitro-substituted amines

Abstract

The free energies of transfer at 25 °C from water to ethylene glycol (EG) for some neutral indicator acids (HA), viz. some t-butyl-substituted phenols and nitro-substituted amines have been determined by use of solubility and partition measurements. Utilizing these data and the known values of the acid dissociation constants, (K_a)_HA, of these acids in water and EG and also the free energy of transfer of a proton, ΔG_t°(H⁺), from water to EG at 25 °C estimated previously, the corresponding free energies of transfer for the anions of these acids, ΔG_t°(A^–), have been determined. An attempt has been made to explain the relative magnitudes of these transfer quantities in terms of the relative structure and charge distribution of these acids and their anions and their possible interaction with water and EG.