Accurate pKa Calculations for Carboxylic Acids Using Complete Basis Set and Gaussian-n Models Combined with CPCM Continuum Solvation Methods”

Authors

George C. Shields, Bucknell UniversityFollow
Matthew D. Liptak

Publication Date

2001

Description

Complete Basis Set and Gaussian-n methods were combined with CPCM continuum solvation methods to calculate pK_a values for six carboxylic acids. An experimental value of −264.61 kcal/mol for the free energy of solvation of H⁺, ΔG_s(H⁺), was combined with a value for G_gas(H⁺) of −6.28 kcal/mol to calculate pK_a values with Cycle 1. The Complete Basis Set gas-phase methods used to calculate gas-phase free energies are very accurate, with mean unsigned errors of 0.3 kcal/mol and standard deviations of 0.4 kcal/mol. The CPCM solvation calculations used to calculate condensed-phase free energies are slightly less accurate than the gas-phase models, and the best method has a mean unsigned error and standard deviation of 0.4 and 0.5 kcal/mol, respectively. The use of Cycle 1 and the Complete Basis Set models combined with the CPCM solvation methods yielded pK_a values accurate to less than half a pK_a unit.

Journal

Journal of the American Chemical Society

Volume

123

First Page

7314

Last Page

7319

Department

Chemistry

Link to Published Version

http://dx.doi.org/10.1021/ja010534f

Recommended Citation

Shields, George C. and Liptak, Matthew D.. "Accurate pKa Calculations for Carboxylic Acids Using Complete Basis Set and Gaussian-n Models Combined with CPCM Continuum Solvation Methods”." Journal of the American Chemical Society (2001) : 7314-7319.