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

Authors

George C. Shields, Bucknell UniversityFollow
Ann Marie Toth
Matthew D. Liptak
Danielle L. Phillips

Publication Date

2001

Description

The complete basis set methods CBS-4, CBS-QB3, and CBS-APNO, and the Gaussian methods G2 and G3 were used to calculate the gas phase energy differences between six different carboxylic acids and their respective anions. Two different continuum methods, SM5.42R and CPCM, were used to calculate the free energy differences of solvation for the acids and their anions. Relative pK_a values were calculated for each acid using one of the acids as a reference point. The CBS-QB3 and CBS-APNO gas phase calculations, combined with the CPCM/HF/6-31+G(d)//HF/6-31G(d) or CPCM/HF/6-31+G(d)//HF/6-31+G(d) continuum solvation calculations on the lowest energy gas phase conformer, and with the conformationally averaged values, give results accurate to ½ pK_a unit. © 2001 American Institute of Physics.

Journal

The Journal of Chemical Physics

Volume

114

First Page

4595

Last Page

4606

Department

Chemistry

Link to Published Version

http://dx.doi.org/10.1063/1.1337862

Recommended Citation

Shields, George C.; Toth, Ann Marie; Liptak, Matthew D.; and Phillips, Danielle L.. "Accurate relative pKa calculations for carboxylic acids using complete basis set and Gaussian-n models combined with continuum solvation methods." The Journal of Chemical Physics (2001) : 4595-4606.