Evaluation of solvent effects on the dissociation of aliphatic carboxylic acids in aqueous N,N-dimethylformamide mixtures according to the scaled particle theory

The standard Gibbs energies of transfer, ΔG t ° from water to water-N,N-dimethylformamide mixtures for the dissociation process of several organic acids (formic, acetic, propionic, n-butyric, isobutyric, n-valeric, isovaleric, 2-methylbutyric and trimethylacetic acids) obtained from the pK a * values are discussed in terms of the extended Scaled Particle Theory from quantum mechanical calculations in order to estimate the cavity and electrostatic contributions. The residual energy term was correlated with the hydrogen bond acceptor density and the Kamlet-Taft β parameters. The main contribution to ΔG t ° was due to dipolar and specific interactions