Computational Studies of Acidities of Some Hyrodxycoumarins

Abstract In this article, various computational approaches were applied to compute proton affinities, gas-phase acidities and aqueous acidities (pKa values) of some hydroxycoumarins. The results indicate that using the thermodynamic cycle involving proton transfer to hydroxide ion is the best method and linear Gibbs free energy relationship could be a trustworthy alternative. This work has improved the previous accuracies obtained and therefore, could be a reliable tool for pKa predictions of other hydroxycoumarins of interest. The pKa value of 5-hydroxycoumarin was predicted using the best approaches equal to 7.9.