Kinetics of the reactions of hydroxyl radical with benzene and toluene
Kinetics of the reactions of hydroxyl radical with benzene and toluene
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DOI：
10.1021/j150615a025
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发表时间：
1981-07
期刊：
影响因子：
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通讯作者：
F. P. Tully;A. Ravishankara;R. Thompson;J. Nicovich;R. C. Shah;N. M. Kreutter;P. Wine
中科院分区：
文献类型：
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作者：
F. P. Tully;A. Ravishankara;R. Thompson;J. Nicovich;R. C. Shah;N. M. Kreutter;P. Wine
以He、Ar和SF/sub 6/为稀释气体，在213 ≤ T ≤ 1150 K和20 ≤ P ≤ 200 K的温度和压力范围内，测定了羟基自由基与苯和甲苯反应的绝对速率常数。为了帮助阐明反应机理随温度的变化，我们还研究了与氘化苯（C/sub 6/D/sub 6/）和选择性氘化甲苯（C/sub 6/H/sub 5/CD/sub 3/、C/sub 6/D/sub 5/CD/sub 3/和C/sub 6/D/sub 5/CH/sub 3/）的OH反应。三个主要的反应通道，其特征在于动力学。在T小于或等于298 K，亲电加成的OH自由基的芳环是占主导地位的反应途径，在所有系统的研究。在高于500 K的温度下，迅速分解的热化加合物回反应物减少的重要性，另外的通道，并导致双分子反应速率常数值显着低于室温附近测得的。在高温下，环氢提取（苯）和侧链氢提取（甲苯）的途径被证明是占主导地位的。在500 K以上，双分子反应速率常数随温度的升高而单调增加，并实现了甲苯两种夺氢模式的动力学分离。«少
Absolute rate constants for the reactions of the hydroxyl radical with benzene and toluene were measured within the temperature and pressure ranges 213 less than or equal to T less than or equal to 1150 K and 20 less than or equal to P less than or equal to 200 torr by using He, Ar, and SF/sub 6/ as diluent gases. To help elucidate the variations in reaction mechanism with temperature, we also studied OH reactions with deuterated benzene (C/sub 6/D/sub 6/) and with selectively deuterated toluenes (C/sub 6/H/sub 5/CD/sub 3/, C/sub 6/D/sub 5/CD/sub 3/, and C/sub 6/D/sub 5/CH/sub 3/). Three major reaction channels were characterized kinetically. At T less than or equal to 298 K, electrophilic addition of the OH radical to the aromatic ring is the dominant reactive pathway in all systems studied. At temperatures above 500 K, rapid decomposition of the thermalized adduct back to reactants diminishes the importance of the addition channel and leads to bimolecular reaction rate-constant values significantly lower than those measured near room temperature. At elevated temperatures, the ring hydrogen abstraction (for benzene) and side-chain hydrogen abstraction (for toluene) pathways are shown to be predominant. The measured bimolecular rate constants increase monotonically withmore » increases in temperature above 500 K, and kinetic separation of the two hydrogen abstraction modes for toluene is achieved.« less