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Formation of Organic Acids and Carbonyl Compounds in $\textit{n}$-Butane Oxidation via γ-Ketohydroperoxide Decomposition
Ist Teil von
Angewandte Chemie (International ed.), 2022-07, Vol.61 (42)
Ort / Verlag
United States: Wiley
Erscheinungsjahr
2022
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
A crucial chain-branching step in autoignition is the decomposition of ketohydroperoxides (KHP) to form an oxy radical and OH. Other pathways compete with chain-branching, such as “Korcek” dissociation of γ-KHP to a carbonyl and an acid. Here we characterize the formation of a γ-KHP and its decomposition to formic acid+acetone products from observations of $\textit{n}$-butane oxidation in two complementary experiments. In jet-stirred reactor measurements, KHP is observed above 590 K. The KHP concentration decreases with increasing temperature, whereas formic acid and acetone products increase. Observation of characteristic isotopologs acetone-$d_3$ and formic acid-$d_0$ in the oxidation of CH3CD2CD2CH3 is consistent with a Korcek mechanism. In laser-initiated oxidation experiments of $\textit{n}$-butane, formic acid and acetone are produced on the timescale of KHP removal. Further, modelling the time-resolved production of formic acid provides an estimated upper limit of 2 s–1 for the rate coefficient of KHP decomposition to formic acid+acetone.