Assessment of pK(a) Determination for Monocarboxylic Acids with an Accurate Theoretical Composite Method: G4CEP

Author(s)

Silva, Cleuton de Souza ^{[1, 2]} ; Custodio, Rogerio ^[1]

Affiliation

^[1] Univ Estadual Campinas, Inst Quim, BR-13083970 Campinas, SP - Brazil

^[2] Univ Fed Amazonas, Inst Ciencias Exatas & Tecnol, Campus Itacoatiara, BR-69100021 Itacoatiara, Amazonas - Brazil

• Document type: Journal article
• Source: Journal of Physical Chemistry A; v. 123, n. 38, p. 8314-8320, SEP 26 2019.
• Web of Science Citations: 0

Abstract

For 22 monoprotic acids, pK(a) values were calculated using the G4CEP composite theory. The solvation effect was included considering the continuous SMD solvation model; SMD and one explicit water molecule; and SMD, one water molecule, and linear correction with respect to the experimental pK(a) values. The three tests provided mean absolute errors equal to 0.83, 0.51, and 0.30 plc units, respectively, indicating excellent performance of the G4CEP method. Comparison with density functional theory at the B3LYP and BMK levels showed that these results are quickly obtained but with a significant error. The best performance of the functionals was obtained from the combination of SMD, one explicit water molecule, linear regression correction, and basis set including diffuse functions. However, the dispersion of the results with DFT can lead to deviations of up to two pK(a) units, whereas for G4CEP the largest deviations seldom exceed one pK(a) unit. (AU)

• FAPESP's process: 13/08293-7 - CCES - Center for Computational Engineering and Sciences
• Grantee: Munir Salomao Skaf
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 17/11485-6 - Computational and theoretical developments based on ab initio methods and the Density Functional Theory
• Grantee: Rogério Custodio
• Support Opportunities: Regular Research Grants