Liang Wei-Che, Luo Pei-Ling, Lee Yuan-Pern
Department of Applied Chemistry and Institute of Molecular Science, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan.
Phys Chem Chem Phys. 2021 May 14;23(18):11082-11090. doi: 10.1039/d1cp00011j. Epub 2021 May 4.
Reactions between Criegee intermediates and hydrogen halides might be significant, particularly in the polluted urban atmosphere, because of their large rate coefficients. Employing a Fourier-transform spectrometer in a step-scan mode or a continuous-scan mode, we recorded infrared spectra of transient species and end products in a flowing mixture of CHI/HCl/N/O irradiated at 308 nm. Five bands near 823.2, 1061.1, 1248.4, 1309.2, and 1359.6 cm were observed and assigned to the gauche-conformer of chloromethyl hydroperoxide (CMHP, CHClOOH). At a later time of the reaction, absorption bands of HO and formyl chloride (CHClO) at 1782.9 cm were observed; these species were likely produced from the secondary reactions of CHClO + O→ CHClO + HO and OH + HCl → HO + Cl according to temporal profiles of CMHP, HO, and CHClO; formation of CHClO + OH via decomposition of internally excited CMHP was predicted by theory and both HCl and O are major species in the system. We investigated also the rate coefficient of the reaction CHOO + HCl on probing CHOO with a continuous-wave infrared quantum-cascade laser absorption system under total pressure 5.2-8.2 torr at 298 K. The rate coefficient k = (4.8 ± 0.4) × 10 cm molecule s, is comparable to the only literature value k = (4.6 ± 1.0) × 10 cm molecule s reported by Foreman et al.
由于其较大的速率系数，克里吉中间体与卤化氢之间的反应可能很重要，特别是在污染的城市大气中。我们使用傅里叶变换光谱仪在步进扫描模式或连续扫描模式下，记录了在308 nm照射的CHI/HCl/N/O流动混合物中瞬态物种和最终产物的红外光谱。在823.2、1061.1、1248.4、1309.2和1359.6 cm附近观察到五个谱带，并将其归属于氯甲基过氧化氢（CMHP，CHClOOH）的gauche-构象体。在反应后期，观察到HO和甲酰氯（CHClO）在1782.9 cm处的吸收带；根据CMHP、HO和CHClO的时间分布，这些物种可能是由CHClO + O→ CHClO + HO和OH + HCl → HO + Cl的二次反应产生的；理论预测通过内部激发的CMHP分解形成CHClO + OH，并且HCl和O都是系统中的主要物种。我们还在298 K、总压力5.2 - 8.2托的条件下，使用连续波红外量子级联激光吸收系统探测CHOO，研究了反应CHOO + HCl的速率系数。速率系数k = (4.8 ± 0.4) × 10 cm³分子⁻¹ s⁻¹，与Foreman等人报道的唯一文献值k = (4.6 ± 1.0) × 10 cm³分子⁻¹ s⁻¹相当。
