Accurate relative pKa calculations for carboxylic acids using complete basis set and Gaussian-n models combined with continuum solvation methods

Abstract

The gas phase energy differences between six different carboxylic acids and their respective anions were calculated by the complete basis set methods and Gaussian methods. Continuum methods were also used for the calculation of the free energy differences of solvations for the acids and their anions. One of the acids was taken as a reference point and relative pKa values were calculated. The most accurate values were obtained when both the gas phase and solvation calculations were performed on the lowest energy gas phase conformers of each acid.