title: Kinetics and mechanism of the Co(II)-assisted oxidation of L-ascorbic acid by dioxygen and nitrite in aqueous solution.
abstract: A detailed study of the oxidation of L-ascorbic acid by dioxygen and nitrite in water at pH 5.8 and 7.0, catalyzed by the octasulfophenyltetrapyrazinoporphyrazine complex of cobalt(II), was carried out using conventional spectrophotometric, low-temperature and high-pressure stopped-flow techniques. The Co(II) complex activates L-ascorbic acid through an intramolecular one-electron oxidation step that involves the reduction of the octasulfophenyltetrapyrazinoporphyrazine. The reaction rate strongly depends on pH due to the different redox behaviour of the L-ascorbic acid/ascorbate species present in solution. Kinetic parameters for the different reaction steps of the catalytic process were determined. The final product of the reaction between L-ascorbic acid and nitrite was found to be nitrous oxide.
authors.affiliation: Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nürenberg, Egerlandstrasse 1, 91058, Erlangen, Germany.
authors.forename: Elena A
authors.initials: EA
authors.lastname: Vlasova
authors.forename: Natalya
authors.initials: N
authors.lastname: Hessenauer-Ilicheva
authors.forename: Denis S
authors.initials: DS
authors.lastname: Salnikov
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Kudrik
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Makarov
authors.forename: Rudi
authors.initials: R
authors.lastname: van Eldik
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009573:Nitrites / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D009573:Nitrites; D009942:Organometallic Compounds; D014867:Water; D003035:Cobalt; D001205:Ascorbic Acid; D010100:Oxygen