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Direct observation and kinetics of a hydroperoxyalkyl radical (QOOH)
Ist Teil von
Science (American Association for the Advancement of Science), 2015-02, Vol.347 (6222), p.643-646
Ort / Verlag
Washington: American Association for the Advancement of Science
Erscheinungsjahr
2015
Quelle
Science Online科学在线
Beschreibungen/Notizen
Oxidation of organic compounds in combustion and in Earth's troposphere is mediated by reactive species formed by the addition of molecular oxygen (O2) to organic radicals. Among the most crucial and elusive of these intermediates are hydroperoxyalkyl radicals, often denoted "QOOH." These species and their reactions with O2 are responsible for the radical chain branching that sustains autoignition and are implicated in tropospheric autoxidation that can form low-volatility, highly oxygenated organic aerosol precursors. We report direct observation and kinetics measurements of a QOOH intermediate in the oxidation of 1,3-cycloheptadiene, a molecule that offers insight into both resonance-stabilized and nonstabilized radical intermediates. The results establish that resonance stabilization dramatically changes QOOH reactivity and, hence, that oxidation of unsaturated organics can produce exceptionally long-lived QOOH intermediates.