DETERMINATION OF pKa AND pKb FROM ELECTRONIC PROPERTIES DERIVED FROM CONCEPTUAL DENSITY FUNCTIONAL THEORY (cDFT)
Author
Muñoz - Espinoza, José
Barriga-González, Germán
Jiménez-Meza, Sergio
Abstract
In the present work we apply a semiempirical method capable of calculating the pka and pkb values of a series of organic acids and bases through their electronic properties. This multilinear model, analogous to the one introduced by Kamlet-Taft, relates acid-base properties such as HBA and HBD to the regional electrophilicity and nucleophilicity derived from cDFT. To test the model, it was applied to a series of mono and dicarboxylic acids, as well as aliphatic/cyclic and heterocyclic amines, showing us that the model is only functional when the series of compounds present similar characteristics such as functional groups. Based on the regionalization of the electrophilicity and nucleophilicity, it can be observed that the acid-base characteristics are not exclusive to limited regions of the molecules, but that these present a bifunctional character that shifts to the relative characteristics of acid and/or base according to the global distribution of the electronic density.