Product Branching Fractions and Kinetic Isotope Effects for the Reactions of OH and OD Radicals with CH3SH and CH3SD
Product Branching Fractions and Kinetic Isotope Effects for the Reactions of OH and OD Radicals with CH3SH and CH3SD
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OH 和 OD 自由基与 CH3SH 和 CH3SD 反应的产物支化分数和动力学同位素效应
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
D. Setser
中科院分区：
文献类型：
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作者：
N. Butkovskaya;D. Setser
由H_2O、HDO和D_2O产物的红外荧光光谱确定了OH和OD自由基与CH_3SH和CH_3SD反应的产物支化分数和动力学同位素效应。通过观察来自放电流反应器的发射的傅里叶变换光谱仪获得光谱。在OD + CH_3SD（或OD + CH_3SH）反应中，从甲基上抽氢占总反应速率的（11 ± 4）%;在OH + CH_3SH（或OH + CH_3SD）反应中，从甲基上抽氢占总反应速率的（24 ± 8）%。主要的产物通道涉及与分子硫端的相互作用。OD和OH反应的支化分数的差异是由于加成-消除通道的大的逆次级动力学同位素效应，其通过氢原子从加合物中的硫原子转移到氧原子而发生。消除通道的过渡态模型进行了讨论，表明实验确定的次级动力学同位素效应的消除通道。
Product branching fractions and kinetic isotope effects for the reactions of OH and OD radicals with CH3SH and CH3SD were determined from the infrared chemiluminescent spectra of the H2O, HDO and D2O products. The spectra were acquired by a Fourier transform spectrometer that viewed the emission from a discharge flow reactor. Abstraction of H atom from the methyl group accounts for (11 ± 4)% of the total reaction rate from the OD + CH3SD (or OD + CH3SH) reaction and for (24 ± 8)% from the OH + CH3SH (or OH + CH3SD) reaction. The major product channel involves interaction with the sulfur end of the molecule. The difference in branching fractions for OD and OH reactions is due to the large inverse secondary kinetic-isotope effect for the addition−elimination channel, which occurs by transfer of the hydrogen atom from the sulfur atom to the oxygen atom in the adduct. Transition state models for the elimination channel are discussed to show that the experimentally determined secondary kinetic isotope effect f...