The OH-radical-initiated oxidation of 3-methyl-3-penten-2-one and 4-methyl-3-penten-2-one was investigated in two atmospheric simulation chambers at 298±3 K and 990±15 mbar using long-path FTIR spectroscopy. The rate coefficients of the reactions of 3-methyl-3-penten-2-one and 4-methyl-3-penten-2-one with OH radicals were determined to be $(\mathrm{6.5}\pm \mathrm{1.2})\times {\mathrm{10}}^{-\mathrm{11}}$ and $(\mathrm{8.1}\pm \mathrm{1.3})\times {\mathrm{10}}^{-\mathrm{11}}$ ${\mathrm{cm}}^{\mathrm{3}}{\mathrm{molecule}}^{-\mathrm{1}}{\mathrm{s}}^{-\mathrm{1}}$, respectively. To enlarge the kinetics data pool the rate coefficients of the target species with Cl atoms were determined to be $(\mathrm{2.8}\pm \mathrm{0.4})\times {\mathrm{10}}^{-\mathrm{10}}$ and $(\mathrm{3.1}\pm \mathrm{0.4})\times {\mathrm{10}}^{-\mathrm{10}}$ ${\mathrm{cm}}^{\mathrm{3}}{\mathrm{molecule}}^{-\mathrm{1}}{\mathrm{s}}^{-\mathrm{1}}$, respectively. The mechanistic investigation of the OH-initiated oxidation focuses on the RO₂+NO reaction. The quantified products were acetoin, acetaldehyde, biacetyl, CO₂ and peroxyacetyl nitrate (PAN) for the reaction of 3-methyl-3-penten-2-one with OH radicals and acetone, methyl glyoxal, 2-hydroxy-2-methylpropanal, CO₂ and peroxyacetyl nitrate (PAN) for the reaction of 4-methyl-3-penten-2-one with OH, respectively. Based on the calculated product yields an upper limit of 0.15 was determined for the yield of RONO₂ derived from the OH reaction of 4-methyl-3-penten-2-one. By contrast, no RONO₂ formation was observed for the OH reaction of 3-methyl-3-penten-2-one. Additionally, a simple model is presented to correct product yields for secondary processes.

中文翻译：

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α,β-不饱和酮的大气氧化：OH自由基反应的动力学和机理

3-methyl-3-penten-2-one 和 4-methyl-3-penten-2-one 在298±3  K 和990±15  mbar 的两个大气模拟室中使用长-path FTIR 光谱。3-甲基-3-戊烯-2-酮和4-甲基-3-戊烯-2-酮与OH自由基反应的速率系数确定为$(\mathrm{6.5}\pm \mathrm{1.2})\times {\mathrm{10}}^{——\mathrm{11}}$ 和 $(\mathrm{8.1}\pm \mathrm{1.3})\times {\mathrm{10}}^{——\mathrm{11}}$ ${\mathrm{厘米}}^{\mathrm{3}}{\mathrm{分子}}^{——\mathrm{1}}{\mathrm{秒}}^{——\mathrm{1}}$， 分别。为了扩大动力学数据池，具有 Cl 原子的目标物种的速率系数被确定为$(\mathrm{2.8}\pm \mathrm{0.4})\times {\mathrm{10}}^{——\mathrm{10}}$ 和 $(\mathrm{3.1}\pm \mathrm{0.4})\times {\mathrm{10}}^{——\mathrm{10}}$ ${\mathrm{厘米}}^{\mathrm{3}}{\mathrm{分子}}^{——\mathrm{1}}{\mathrm{秒}}^{——\mathrm{1}}$， 分别。OH 引发氧化的机理研究集中在RO ₂ +NO反应上。量化产物为乙偶姻，乙醛，联乙酰，CO ₂和硝酸过氧化乙酰（PAN）为的反应3-甲基-3-戊烯-2-酮与OH自由基和丙酮，甲基乙二醛，2-羟基-2-甲基丙醛，CO ₂和过氧乙酰硝酸酯 (PAN) 分别用于 4-methyl-3-penten-2-one 与 OH 的反应。基于计算的产物产率，确定了衍生自 4-甲基-3-戊烯-2-酮的 OH 反应的RONO ₂产率的上限为 0.15 。相比之下，没有RONO ₂观察到 3-methyl-3-penten-2-one 的 OH 反应形成。此外，还提供了一个简单的模型来校正二次加工的产品产量。