Bradley University, Mund-Lagowski Department of Chemistry and Biochemistry, Peoria, IL 61606
Quantum chemical modeling of ions in solution can be challenging, as solvent models often produce inaccurate ΔGsolv values. In the interest of choosing a solvation model for use in modeling an organic reaction with anionic intermediates, pKa and ΔG*solv values of selected organic molecules were calculated and compared to experimental values, to gauge accuracy of the solvation models. The pKa and ΔG*solv of acetic acid, benzoic acid, ethanol, and methanol were calculated in water and methanol using density functional theory calculations and various continuum solvation models. The SM8 model was found to be most accurate in the calculation of pKa and ΔG*solv in water with a mean absolute deviation of 5.0 pKa units and 2.1 kcal/mol. Results for the pKa in methanol were closer to experimental results, with a mean absolute deviation of 1.6 pKa units.
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