title: Base (O.-2, e-, or OH-)-induced autoxygenation of organic substrates: a model chemical system for cytochrome P-450-catalyzed monoxygenation and dehydrogenation by dioxygen.
abstract: When catalytic quantities of superoxide ion (O.-2; or of electrons from electrolysis or of OH-) are introduced into a dry acetonitrile solution that contains excess substrate (RH), ambient air (O2), 1,2-diphenylhydrazine (PhNHNHPh), and iron(II), the substrate is rapidly and efficiently monoxygenated (e.g., triphenylphosphine----triphenylphosphine oxide, benzyl alcohol----benzaldehyde, diphenylsulfoxide----diphenylsulfone) or dehydrogenated (1,4-cyclohexadiene----benzene). The model consists of (i) an O2-activation segment that produces H2O2 from an O.-2-initiated autoxidation of disubstituted hydrazine (a model for reduced flavin), (formula; see text) and (ii) a H2O2-activation segment via the iron(II)-induced formation of ferryl ion (FeO2+), Fe(II) + H2O2----FeO2 + H2O, an effective monoxygenating agent: FeO2+ + RH----Fe(II) + ROH. The combination of i and ii provides a catalytic system for the autoxidation of organic substrates with reaction cycles that are similar to those for cytochrome P-450 monoxygenases.
mesh_terms: D003577:Cytochrome P-450 Enzyme System; D004583:Electrons; D005609:Free Radicals; D006878:Hydroxides; D017665:Hydroxyl Radical; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000494:pharmacology*; D010105:Oxygenases / Q000378:metabolism*; D013481:Superoxides
chemical_list: D005609:Free Radicals; D006878:Hydroxides; D013481:Superoxides; D017665:Hydroxyl Radical; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; D010100:Oxygen