Oxidation mechanism of aromatic peroxy and bicyclic radicals from OH-toluene reactions.
Oxidation mechanism of aromatic peroxy and bicyclic radicals from OH-toluene reactions.
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DOI：
10.1021/ja0350280
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发表时间：
2003-09
影响因子：
15
通讯作者：
I. Suh;Renyi Zhang;L. Molina;M. Molina
中科院分区：
文献类型：
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作者：
I. Suh;Renyi Zhang;L. Molina;M. Molina
对羟基引发甲苯氧化反应的机理特征进行了理论计算。在大气条件下，由初始OH和随后的O(2)加成到甲苯环上的芳香族过氧基是环合生成双环自由基，而不是与NO反应。双环自由基异构化为更稳定的环氧化物自由基具有明显更高的势垒，因此比O(2)加成生成双环过氧化氢自由基的速度慢。在每个羟基结合部位，只有一条通过双环过氧基的异构化途径可以导致环的裂解。这项研究为定量评估臭氧的光化学生产潜力以及甲苯氧化形成有毒产物和二次有机气溶胶提供了热化学和动力学数据。
Theoretical calculations have been performed to investigate mechanistic features of OH-initiated oxidation reactions of toluene. Aromatic peroxy radicals arising from initial OH and subsequent O(2) additions to the toluene ring are shown to cyclize to form bicyclic radicals rather than undergoing reaction with NO under atmospheric conditions. Isomerization of bicyclic radicals to more stable epoxide radicals possesses significantly higher barriers and, hence, has slower rates than O(2) addition to form bicyclic peroxy radicals. At each OH attachment site, only one isomeric pathway via the bicyclic peroxy radical is accessible to lead to ring cleavage. The study provides thermochemical and kinetic data for quantitative assessment of the photochemical production potential of ozone and formation of toxic products and secondary organic aerosol from toluene oxidation.