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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Detection and Identification of the Keto-Hydroperoxide (HOOCH2OCHO) and Other Intermediates during Low-Temperature Oxidation of Dimethyl Ether
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Detection and Identification of the Keto-Hydroperoxide (HOOCH2OCHO) and Other Intermediates during Low-Temperature Oxidation of Dimethyl Ether

机译：二甲基醚低温氧化过程中酮基过氧化氢（HOOCH2OCHO）和其他中间体的检测与鉴定

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摘要

In this paper we report the detection and identification of the keto-hydroperoxide (hydroperoxymethyl formate, HPMF, HOOCH2OCHO) and other partially oxidized intermediate species arising from the low-temperature (540 K) oxidation of dimethyl ether (DME). These observations were made possible by coupling a jet-stirred reactor with molecular-beam sampling capabilities, operated near atmospheric pressure, to a reflectron time-of-flight mass spectrometer that employs single-photon ionization via tunable synchrotron-generated vacuumultraviolet radiation. On the basis of experimentally observed ionization thresholds and fragmentation appearance energies, interpreted with the aid of ab initio calculations, we have identified HPMF and its conceivable decomposition products HC(O)O(O)CH (formic acid anhydride), HC(O)OOH (performic acid), and HOC(O)OH (carbonic acid). Other intermediates that were detected and identified include HC(O)OCH3 (methyl formate), cycl-CH2-O-CH2-O- (1,3-dioxetane), CH3OOH (methyl hydroperoxide), HC(O)OH (formic acid), and H2O2 (hydrogen peroxide). We show that the theoretical characterization of multiple conformeric structures of some intermediates is required when interpreting the experimentally observed ionization thresholds, and a simple method is presented for estimating the importance of multiple conformers at the estimated temperature (similar to 100 K) of the present molecular beam. We also discuss possible formation pathways of the detected species: for example, supported by potential energy surface calculations, we show that performic acid may be a minor channel of the O-2 + CH2OCH2OOH reaction, resulting from the decomposition of the HOOCH2OCHOOH intermediate, which predominantly leads to the HPMF.
机译：在本文中，我们报告了由二甲醚（DME）的低温（540 K）氧化引起的酮基氢过氧化物（甲酸氢过氧甲酯，HPMF，HOOCH2OCHO）和其他部分氧化的中间物质的检测和鉴定。通过将在大气压力下操作的具有分子束采样功能的搅拌式反应器与通过可调同步加速器产生的真空紫外辐射采用单光子电离的反射式飞行时间质谱仪耦合，可以使这些观察成为可能。根据实验观察到的电离阈值和碎片外观能，并通过从头算算得到解释，我们确定了HPMF及其可能的分解产物HC（O）O（O）CH（甲酸酐），HC（O） OOH（过甲酸）和HOC（O）OH（碳酸）。检测和鉴定的其他中间体包括HC（O）OCH3（甲酸甲酯），环-CH2-O-CH2-O-（1,3-二氧杂环丁烷），CH3OOH（甲基氢过氧化物），HC（O）OH（甲酸）和H2O2（过氧化氢）。我们表明，在解释实验观察到的电离阈值时，需要一些中间体的多重构象结构的理论表征，并提出了一种简单的方法来估算在本分子的估计温度（类似于100 K）下多个构象异构体的重要性。光束。我们还讨论了被检测物种的可能形成途径：例如，在势能面计算的支持下，我们表明，过甲酸可能是O-2 + CH2OCH2OOH反应的次要通道，这是由于HOOCH2OCHOOH中间体的分解所致。主要导致HPMF。

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