Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, CA 94551-0969, USA.
Phys Chem Chem Phys. 2013 Jul 14;15(26):10753-60. doi: 10.1039/c3cp51185e. Epub 2013 May 21.
Hydrocarbon autoignition has long been an area of intense fundamental chemical interest, and is a key technological process for emerging clean and efficient combustion strategies. Carbon-centered radicals containing an -OOH group, commonly denoted ˙QOOH radicals, are produced by isomerization of the alkylperoxy radicals that are formed in the first stages of oxidation. These ˙QOOH radicals are among the most critical species for modeling autoignition, as their reactions with O2 are responsible for chain branching below 1000 K. Despite their importance, no ˙QOOH radicals have ever been observed by any means, and only computational and indirect experimental evidence has been available on their reactivity. Here, we directly produce a ˙QOOH radical, 2-hydroperoxy-2-methylprop-1-yl, and experimentally determine rate coefficients for its unimolecular decomposition and its association reaction with O2. The results are supported by high-level theoretical kinetics calculations. Our experimental strategy opens up a new avenue to study the chemistry of ˙QOOH radicals in isolation.
碳氢化合物的自动点火一直是基础化学领域的一个热点，也是新兴清洁高效燃烧策略的关键技术过程。含有-OOH 基团的碳中心自由基，通常表示为˙QOOH 自由基，是在氧化的最初阶段形成的过烷基自由基异构化产生的。这些˙QOOH 自由基是自动点火模型中最重要的物种之一，因为它们与 O2 的反应负责在 1000 K 以下的链分支。尽管它们很重要，但到目前为止，还没有任何方法可以观察到任何˙QOOH 自由基，而且只有关于它们反应性的计算和间接实验证据。在这里，我们直接生成了一个˙QOOH 自由基，2-过氧-2-甲基丙-1-基，并通过实验确定了其单分子分解和与 O2 缔合反应的速率系数。结果得到了高水平理论动力学计算的支持。我们的实验策略为研究 ˙QOOH 自由基的化学性质开辟了一条新途径。
