Publication Details
Category Text Publication
Reference Category Journals
DOI 10.1063/1.477614
Title (Primary) Quantum chemical analysis of the energy of proton transfer from phenol and chlorophenols to H2O in the gas phase and in aqueous solution
Author Schüürmann, G.
Journal Journal of Chemical Physics
Year 1998
Department OEC; COE
Volume 109
Issue 21
Page From 9523
Page To 9528
Language englisch
Abstract Proton transferenergies of phenol and 14 chlorophenols with H 2 O  as a base are analyzed in the gas phase and in solution using quantum chemical methods at the semiempirical and ab initio level of computation. The effect of aqueous solution was accounted for by applying the density functional theory(DFT) implementation of the conductor-like screening model (COSMO) as well as semiempirical continuum-solvation models. The results reveal substantial and systematic overestimations of the free energies of proton transfer as derived from experimental solution-phase pK a   data. This can be traced back to both deficiencies in the current model parameterization as well as to limitations of the underlying gas-phase quantum chemical models, which is further illustrated by additional complete-basis-set (CBS) calculations for the proton transferreaction with phenol. In contrast, the relative pK a   trend is reflected well by COSMO-DFT calculations with correlation coefficients (adjusted for degrees of freedom) of 0.96. Decomposition of the dissociation energy in aqueous solution into a gas-phase term and a term summarizing the solvation contributions provides new insights into the effect of solvation on proton transferenergies, and yields mechanistic explanations for the observed differences in the gas-phase and solution-phase acidity orders of various subgroups of the compounds
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=8997
Schüürmann, G. (1998):
Quantum chemical analysis of the energy of proton transfer from phenol and chlorophenols to H2O in the gas phase and in aqueous solution
J. Chem. Phys. 109 (21), 9523 - 9528