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Unexpected Superoxide Dismutase Antioxidant Activity of Ferric Chloride in Acetonitrile

From National Research Council Canada

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DOIResolve DOI: https://doi.org/10.1021/jo034908u
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Affiliation
  1. National Research Council of Canada
FormatText, Article
Subjectcatalysis; free radicals; oxidation; reaction kinetics; chain reactions; organic compounds; 4 cymene; acetonitrile; antioxidant; azobis(isobutyronitrile); copper chloride; ferric chloride; hydrogen peroxide; hydroperoxyl radical; radical; superoxide dismutase; terpinene; unclassified drug; antioxidant activity; autooxidation; catalysis; chemical reaction kinetics; peroxidation; reaction analysis; steady state; temperature; acetonitriles; antioxidants; ferric compounds; kinetics; oxidation-reduction; superoxide dismutase
Abstract
The azobis(isobutyronitrile)-initiated autoxidation of γ-terpinene in acetonitrile at 50 °C yields onlyp-cymene and hydrogen peroxide (1:1) in a chain reaction carried by the hydroperoxyl radical, HOO. (Foti, M. C.; Ingold, K. U. J. Agric. Food Chem. 2003, 51, 2758-2765). This reaction is retarded by very low (μM) concentrations of FeCl3 and CuCl 2. The kinetics of the FeCl3-inhibited autoxidation are consistent with chain-termination via the following: Fe3+ + HOO . ⇄ [FeIV-OOH]3+ and [Fe IV-OOH]3+ + HOO. → Fe3+ + H2O2 + O2. Thus, FeCl3 in acetonitrile can be regarded as a very effective (and very simple) superoxide dismutase. The kinetics of the CuCl2-inhibited autoxidation indicate that chain transfer occurs and becomes more and more important as the reaction proceeds, i.e., the inhibition is replaced by autocatalysis. These kinetics are consistent with-reduction of Cu2+ to Cu+ by HOO . and then the reoxidation of Cu+ to Cu2+ by both HOO. and the H2O2 product. The latter reaction yields HO. radicals which continue the chain.
Publication date
PublisherAmerican Chemical Society
In
  • Journal of Organic Chemistry 68, no. 23: 9162–9165.
LanguageEnglish
Peer reviewedYes
NPARC number21276743
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Record identifier3cc8ce46-8af0-4805-8680-ddade1c73fce
Record created2015-10-13
Record modified2020-06-02
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