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Quantum chemical study of the autoxidation of ascorbate
Author(s) -
Herrmann Nils,
Heinz Norah,
Dolg Michael,
Cao Xiaoyan
Publication year - 2016
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.24408
Subject(s) - autoxidation , chemistry , ascorbic acid , ab initio , density functional theory , gibbs free energy , quantum chemical , redox , computational chemistry , hybrid functional , thermodynamics , molecule , inorganic chemistry , organic chemistry , physics , food science
Reactions involved in the autoxidation of ascorbate have been investigated with quantum chemical first‐principles and ab initio methods. Reaction energies and Gibbs energies of the reactions were calculated at the density functional theory level applying the gradient‐corrected BP86 and the hybrid B3LYP functionals together with def2‐TZVP basis sets. Results of single‐point CC2, CCSD, and CCSD(T) calculations were used for calibration of the density functional theory data and show excellent agreement with the B3LYP values. Based on the Gibbs energy ascorbic acid AscH 2 is found to be the energetically lowest species in aqueous solution, whereas the monoanion ascorbate AscH−is the most abundant one near pH = 7. Asc2 −was found to be the preferred reducing agent for autoxidation and oxidation processes. The results also support a metal‐catalyzed synthesis of the reactive oxygen species H 2 O 2 according to a redox cycling mechanism proposed in literature. © 2016 Wiley Periodicals, Inc.