Gallic acid: thermodynamics of the homolytic and heterolytic phenolic O—H bonds splitting-off
Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, Slovak Republic
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Abstract: The DFT study of primary antioxidant action of gallic acid and its carboxylic anion is presented in the gas-phase, benzene and water. Corresponding reaction enthalpies for three possible mechanisms was calculated using B3LYP/6-311++G** method. Bond dissociation enthalpy (BDE) and proton dissociation enthalpy (PDE) of 4-OH group was found to be the lowest in gas-phase as well as in both solvents approximated by IEF-PCM model. Ionization potentials (IPs) were higher than BDEs in all cases. Deprotonation of carboxylic group result in increased antioxidant potency as drop in BDE and IPs was indicated in all environments.
Keywords: hydrogen atom transfer, sequential proton-loss electron-transfer, deprotonation, bond dissociation enthalpy, proton affinity
Full paper in Portable Document Format: acs_0251.pdf
Acta Chimica Slovaca, Vol. 9, No. 2, 2016, pp. 114—123, DOI: 10.1515/acs-2016-0020