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Analysis is made of reported results on the kinetics and mechanism of ascorbic acid oxidation with oxygen in the presence of cupric ions. The diversities due to methodological reasons are cleared up. A kinetic study of the mechanism of Cu2+ anaerobic reaction with ascorbic acid (DH2) is carried out. The true kinetic regularities of catalytic ascorbic acid oxidation with oxygen are established at 2.7 6 pH < 4,5 X 6 [Cu2+] d 10-3M, and Wo = K~[CU~+][DH~][O~]~.~/[H+]where ~1 (25OC) = 0.13 f 0.01 M-o.5.sec-1. The activation energy for this reaction is E1 = 22 f 1 kcal/mol. It is found by means of adding Cu+ acceptors (acetonitrile and ally1 alcohol) that the catalytic process is of a chain nature. The Cu+ ion generation at the interaction of the Cu2+ ion with ascorbic acid is the initiation step. The rate of the chain initiation at where K~J (25OC) = (1.8 f 0.3)M-1-sec-1, Ei,l = 31 f 2 kcal/mol. The reaction of the Cu+ ion with 0 2 is involved in a chain propagation, so that the rate of catalytic ascorbic acid oxidation for the system Cu2+-DHz-02 is

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The mechanism of the interaction of Cu+-a,a'-dipyridyl complex (Cu+Lz) with 0 2 in both neutral and acid media was studied by the stopped-flow method. The dependence of the mechanism on the acidity of the medium was established. In an acid medium H+ participated in a direct 0 2 reduction to HOn by interaction with an oxygen adduct L&u+O2 formed without displacement of ligand molecules. In a neutral medium the reaction rate was limited by inner sphere charge transfer from Cu+ to 0 2 to form an oxygen "charge transfer" complex L2CuOt. The latter interacted either with the second ion Cu+L2 or with the free ligand, or else it dissociated, reversibly or irreversibly, to form a radical anion 0;. The bimolecular rate constants of the oxygen "adduct" and "charge transfer" complex formation appeared to be kbi = (1.0 f 0.1) X lo5 and (1.5 f 0.2) X 104M-'-sec-', respectively. The effective termolecular rate constants of 0 2 reduction to H02 in an acid medium (with contribution from H+) and to 0; in a neutral medium (with contribution from a,a'-dipyridyl) were k,,, = 2.7 X lo8 and 107M-2.sec-1. The rate constants of the elementary steps were estimated. The auto-oxidation mechanism of the aquoion and complexes of Cu+ is discussed in terms of the results obtained.