Solvation enthalpies of the proton in polar and non-polar solvents: Theoretical study

Abstract

In spite of the importance of proton transfer in solution-phase processes, there is still no systematic theoretical study of proton solvation enthalpies. We have investigated the solvation enthalpies of the proton in seven solvents of various polarities (benzene, chloroform, acetone, methanol, ethanol, DMSO, water) using the Integral Equation Formalism Polarized Continuum Model (IEF-PCM). All computations were performed at the B3LYP and BHLYP levels of theory with aug-cc-pVDZ, aug-cc-pVTZ and aug-cc-pVQZ basis sets. Our calculations have shown that the B3LYP and BHLYP functionals provide similar solvation enthalpies. Finally, differences in the solvation enthalpy of the proton values stemming from the various basis sets do not exceed 6 kJ mol -1 , with exception of DMSO and chloroform. Distance between H + and the acceptor atom of the solvent molecule is the shortest in the case of water. It has been also found that the B3LYP distances are slightly longer.

Solvation enthalpies and Gibbs energies of the proton and electron: Influence of solvation models

“…A comparison of the results of the present investigation obtained by using C-PCM to those obtained by employing SMD reveals that C-PCM produces slightly more negative (less positive) solvation enthalpies and Gibbs energies of the electron, and less negative values for the proton. These results are also in accord with those suggested by (Rottmannová et al 2013) and (Škorňa et al 2014), where the IEF-PCM solvation model was used.…”

“…which is embedded in dielectric continuum (Fifen et al 2011;Rottmannová et al 2013;Marković et al 2013;Škorňa et al 2014):…”

“…On the other hand, the results for solvation enthalpies and Gibbs energies of the proton and electron in other solvents are still limited (Fifen et al 2011;Fifen et al 2013;Rottmannová et al 2013;Marković et al 2013;Škorňa et al 2014). In a recent paper, a comprehensive examination of the solvation enthalpies and Gibbs energies of the proton and electron in twenty solvents of different polarities was carried out (Marković et al 2016).…”

Large‐Sized Ammonia Clusters and Solvation Energies of the Proton in Ammonia

“…Several investigations have been performed to determine the solvation energies of the proton in water . Besides, only few authors have been interested in the solvation energies of the proton in other solvents such as methanol, acetonitrile, dimethyl sulfoxide, acetone, benzene, ethanol, and ammonia . Recently, we reported the solvation free energy and the solvation enthalpy of the proton in ammonia and in methanol at a wide range of temperatures .…”

“…[5][6][7][8][9][10][11][12][13][14][15] Besides, only few authors have been interested in the solvation energies of the proton in other solvents such as methanol, acetonitrile, dimethyl sulfoxide, acetone, benzene, ethanol, and ammonia. [4,[16][17][18][19][20][21][22][23] Recently, we reported the solvation free energy and the solvation enthalpy of the proton in ammonia and in methanol at a wide range of temperatures. [24,25] In all these investigations, the commonly used methods were the scheme of Tawa et al [5] and the cluster pair correlation approximation (CPA) of Tissandier et al [6] In the scheme of Tawa et al, [5] few ammonia molecules (~10 ammonia molecules) around the proton are treated quantum mechanically, whereas the remaining ammonia molecules, which are far from the proton, are considered as a dielectric continuum medium.…”