Rate constants for the reactions of OH radicals with 1,2,4,5-tetramethylbenzene, pentamethylbenzene, 2,4,5-trimethylbenzaldehyde, 2,4,5-trimethylphenol, and 3-methyl-3-hexene-2,5-dione and products of OH + 1,2,4,5-tetramethylbenzene.
Rate constants for the reactions of OH radicals with 1,2,4,5-tetramethylbenzene, pentamethylbenzene, 2,4,5-trimethylbenzaldehyde, 2,4,5-trimethylphenol, and 3-methyl-3-hexene-2,5-dione and products of OH + 1,2,4,5-tetramethylbenzene.
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DOI：
10.1021/jp400323n
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发表时间：
2013-03
期刊：
影响因子：
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通讯作者：
S. M. Aschmann;J. Arey;R. Atkinson
中科院分区：
文献类型：
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作者：
S. M. Aschmann;J. Arey;R. Atkinson
用相对速率法测定了OH自由基与1,2,4,5-四甲基苯、五甲基苯、2,4,5-三甲基苯甲醛、2,4,5-三甲基苯酚和3-甲基-3-己烯-2,5-二酮在298±2 K和大气压力下的反应速率常数。得到的速率常数(以10(-11)cm（3)分子（-1）s（-1）为单位）为：1,2,4,5-四甲基苯，5.55±0.34；五甲基苯，10.3±0.8；2,4,5-三甲基苯甲醛，4.27±0.39；2,4,5-三甲基苯酚，9.75±0.98；3-甲基-3-己烯-2,5-二酮，9.4±1.1。在NO的存在下，OH + 1,2,4,5-四甲基苯反应得到了以下第一代产物：双乙酰、甲基乙二醛、3-甲基-3-己烯-2,5-二酮和2,4,5-三甲基苯甲醛。测定的3-甲基-3-己烯-2,5-二酮和2,4,5-三甲基苯甲醛的摩尔生成率分别为45±9%和3.3±0.7%，其中3-甲基-3-己烯-2,5-二酮的摩尔生成率外推至低NO2浓度下，oh -1,2,4,5-四甲基苯加合物仅与O2反应。双乙酰基似乎是作为第一代和第二代产物形成的，第一代的形成率为9±3%。甲基乙二醛的相对生成率约为3-甲基-3-己烯-2,5-二酮的0.8，表明甲基乙二醛和3-甲基-3-己烯-2,5-二酮是副产物。从OH + 1,2,4,5-四甲基苯中提取h原子估计占整个OH自由基反应的3.7±0.8%。根据目前对OH-芳香加合物+ O2反应机理的了解，观察到的双乙酰的形成表明，OH + 1,2,4,5-四甲基苯发生了OH的ipso加成。
Using a relative rate method, rate constants have been measured for the reactions of OH radicals with 1,2,4,5-tetramethylbenzene, pentamethylbenzene, 2,4,5-trimethylbenzaldehyde, 2,4,5-trimethylphenol and 3-methyl-3-hexene-2,5-dione at 298 ± 2 K and atmospheric pressure of air. The rate constants obtained (in units of 10(-11) cm(3) molecule(-1) s(-1)) were: 1,2,4,5-tetramethylbenzene, 5.55 ± 0.34; pentamethylbenzene, 10.3 ± 0.8; 2,4,5-trimethylbenzaldehyde, 4.27 ± 0.39; 2,4,5-trimethylphenol, 9.75 ± 0.98; and 3-methyl-3-hexene-2,5-dione, 9.4 ± 1.1. The following first-generation products were identified from the OH + 1,2,4,5-tetramethylbenzene reaction in the presence of NO: biacetyl, methylglyoxal, 3-methyl-3-hexene-2,5-dione, and 2,4,5-trimethylbenzaldehyde. The measured molar formation yields for 3-methyl-3-hexene-2,5-dione and 2,4,5-trimethylbenzaldehyde were 45 ± 9% and 3.3 ± 0.7%, with that for 3-methyl-3-hexene-2,5-dione being extrapolated to low NO2 concentrations where the OH-1,2,4,5-tetramethylbenzene adducts react only with O2. Biacetyl appeared to be formed as both a first- and second-generation product, and a first-generation formation yield of 9 ± 3% was derived. The relative formation yield of methylglyoxal was ~0.8 of that for 3-methyl-3-hexene-2,5-dione, indicating that methylglyoxal and 3-methyl-3-hexene-2,5-dione are coproducts. H-atom abstraction from OH + 1,2,4,5-tetramethylbenzene is estimated to account for 3.7 ± 0.8% of the overall OH radical reaction. On the basis of the current understanding of the mechanism of the OH-aromatic adduct + O2 reaction, the observed formation of biacetyl indicates that some ipso addition of OH occurs for OH + 1,2,4,5-tetramethylbenzene.