Allen Hannah M, Crounse John D, Bates Kelvin H, Teng Alexander Paichung, Krawiec-Thayer Mitchell P, Rivera-Rios Jean C, Keutsch Frank N, St Clair Jason M, Hanisco Thomas F, Møller Kristian H, Kjaergaard Henrik G, Wennberg Paul O
Department of Chemistry , University of Wisconsin Madison , Madison , Wisconsin 53706 , United States.
Paulson School of Engineering and Applied Sciences and Department of Chemistry and Chemical Biology , Harvard University , Cambridge , Massachusetts 02138 , United States.
J Phys Chem A. 2018 Aug 2;122(30):6292-6302. doi: 10.1021/acs.jpca.8b04577. Epub 2018 Jul 24.
Hydroxymethyl hydroperoxide (HMHP), formed in the reaction of the C Criegee intermediate with water, is among the most abundant organic peroxides in the atmosphere. Although reaction with OH is thought to represent one of the most important atmospheric removal processes for HMHP, this reaction has been largely unstudied in the laboratory. Here, we present measurements of the kinetics and products formed in the reaction of HMHP with OH. HMHP was oxidized by OH in an environmental chamber; the decay of the hydroperoxide and the formation of formic acid and formaldehyde were monitored over time using CFO chemical ionization mass spectrometry (CIMS) and laser-induced fluorescence (LIF). The loss of HMHP by reaction with OH is measured relative to the loss of 1,2-butanediol [ k = (27.0 ± 5.6) × 10 cm molecules]. We find that HMHP reacts with OH at 295 K with a rate coefficient of (7.1 ± 1.5) × 10 cm molecules, with the formic acid to formaldehyde yield in a ratio of 0.88 ± 0.21 and independent of NO concentration (3 × 10 - 1.5 × 10 molecules cm). We suggest that, exclusively, abstraction of the methyl hydrogen of HMHP results in formic acid, while abstraction of the hydroperoxy hydrogen results in formaldehyde. We further evaluate the relative importance of HMHP sinks and use global simulations from GEOS-Chem to estimate that HMHP oxidation by OH contributes 1.7 Tg yr (1-3%) of global annual formic acid production.
在Criegee中间体与水的反应中形成的羟甲基过氧化氢（HMHP）是大气中最丰富的有机过氧化物之一。尽管与OH的反应被认为是HMHP最重要的大气去除过程之一，但该反应在实验室中基本上未被研究。在这里，我们展示了HMHP与OH反应的动力学和产物的测量结果。HMHP在环境舱中被OH氧化；使用化学电离飞行时间质谱（CIMS）和激光诱导荧光（LIF）随时间监测过氧化物的衰减以及甲酸和甲醛的形成。相对于1,2 - 丁二醇的损失测量了HMHP与OH反应的损失 [k = (27.0 ± 5.6) × 10 cm³分子⁻¹ s⁻¹]。我们发现，HMHP在295 K下与OH反应的速率系数为(7.1 ± 1.5) × 10⁻¹¹ cm³分子⁻¹ s⁻¹，甲酸与甲醛的产率比为0.88 ± 0.21，且与NO浓度（3 × 10¹¹ - 1.5 × 10¹²分子 cm⁻³）无关。我们认为，仅HMHP的甲基氢的夺取会产生甲酸，而过氧氢的夺取会产生甲醛。我们进一步评估了HMHP汇的相对重要性，并使用GEOS - Chem的全球模拟来估计，OH对HMHP的氧化贡献了全球每年甲酸产量的1.7 Tg yr⁻¹（1 - 3%）。
