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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >13C, O-18, and D Fractionation Effects in the Reactions of CH3OH Isotopologues with Cl and OH Radicals
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13C, O-18, and D Fractionation Effects in the Reactions of CH3OH Isotopologues with Cl and OH Radicals

机译：CH3OH同位素同Cl和OH自由基反应中的13C，O-18和D分离作用

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摘要

A relative rate experiment is carried out for six isotopologues of methanol and their reactions with OH and Cl radicals. The reaction rates of CH2DOH, CHD2OH, CD3OH, (CH3OH)-C-13, and (CH3OH)-O-18 with Cl and OH radicals are measured by long-path FTIR spectroscopy relative to CH3OH at 298 +/- 2 K and 1013 +/- 10 mbar. The OH source in the reaction chamber is photolysis of ozone to produce O(D-1) in the presence of a large excess of molecular hydrogen: O(D-1) + H-2 -> OH + H. Cl is produced by the photolysis of Cl-2. The FTIR spectra are fitted using a nonlinear least-squares spectral fitting method with measured high-resolution infrared spectra as references. The relative reaction rates defined as alpha = k(light)/k(heavy) are determined to be: k(OH + CH3OH)/k(OH) + (CH3OH)-C-13 = 1.031 +/- 0.020, k(OH) + CH3OH/k(OH) + (CH3OH)-O-18 = 1.017 +/- 0.012, k(OH + CH3OH)/k(OH + CH2DOH) = 1.119 +/- 0.045, k(OH + CH3OH)/k(OH + CHD2OH) = 1.326 +/- 0.021 and k(OH + CH3,OH)/k(OH + CD3OH) = 2.566 +/- 0.042, k(Cl + CH3OH)/k(Cl + 13CH3OH) = 1.055 +/- 0.016, k(Cl + CH3OH/) k(Cl + CH318OH) = 1.025 +/- 0.022, k(Cl + CH3OH)/k(Cl + CH2DOH) = 1. 162 +/- 0.022 and k(Cl + CH3OH)/k(Cl + CHD2OH) = 1.536 +/- 0.060, and k(Cl + CH3OH)/k(Cl + CD3OH) = 3.011 +/- 0.059. The errors represent 2 sigma from the statistical analyses and do not include possible systematic errors. Ground-state potential energy hypersurfaces of the reactions were investigated in quantum chemistry calculations at the CCSD(T) level of theory with an extrapolated basis set. The H-2, C-13, and O-18 kinetic isotope effects of the OH and Cl reactions with CH3OH were further investigated using canonical variational transition state theory with small curvature tunneling and compared to experimental measurements as well as to those observed in CH4 and several other substituted methane species.
机译：对甲醇的六个同位素及其与OH和Cl自由基的反应进行了相对速率实验。 CH2DOH，CHD2OH，CD3OH，（CH3OH）-C-13和（CH3OH）-O-18与Cl和OH自由基的反应速率是通过长波FTIR光谱相对于CH3OH在298 +/- 2 K和1013 +/- 10毫巴反应室中的OH源是在大量过量的分子氢的存在下臭氧的光解以产生O（D-1）：O（D-1）+ H-2-> OH + H. Cl-2的光解。使用非线性最小二乘光谱拟合方法拟合FTIR光谱，并以测量的高分辨率红外光谱作为参考。确定为α= k（轻）/ k（重）的相对反应速率为：k（OH + CH3OH）/ k（OH）+（CH3OH）-C-13 = 1.031 +/- 0.020，k（ OH）+ CH3OH / k（OH）+（CH3OH）-O-18 = 1.017 +/- 0.012，k（​​OH + CH3OH）/ k（OH + CH2DOH）= 1.119 +/- 0.045，k（OH + CH3OH） / k（OH + CHD2OH）= 1.326 +/- 0.021和k（OH + CH3，OH）/ k（OH + CD3OH）= 2.566 +/- 0.042，k（Cl + CH3OH）/ k（Cl + 13CH3OH）= 1.055 +/- 0.016，k（Cl + CH3OH /）k（Cl + CH318OH）= 1.025 +/- 0.022，k（Cl + CH3OH）/ k（Cl + CH2DOH）= 1 162 +/- 0.022和k（ Cl + CH3OH）/ k（Cl + CHD2OH）= 1.536 +/- 0.060，k（Cl + CH3OH）/ k（Cl + CD3OH）= 3.011 +/- 0.059。误差代表统计分析得出的2 sigma，不包括可能的系统误差。反应的基态势能超表面在理论化学的CCSD（T）水平下用外推的基础集进行了量子化学计算。使用具有小曲率隧穿的规范变分过渡态理论进一步研究了OH和Cl与CH3OH反应的H-2，C-13和O-18动力学同位素效应，并将其与实验测量值以及在CH4中观察到的结果进行了比较以及其他几种取代的甲烷。

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