The atmospheric oxidation mechanism of acetophenone initiated by the hydroxyl radicals
The atmospheric oxidation mechanism of acetophenone initiated by the hydroxyl radicals
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DOI：
10.1016/j.atmosenv.2023.119905
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发表时间：
2023-09
影响因子：
5
通讯作者：
Beiran Yang;Aobo Liang;Liming Wang
中科院分区：
文献类型：
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作者：
Beiran Yang;Aobo Liang;Liming Wang
苯乙酮 (C8H8O, AP) 是一种常见的室内空气成分，但没有关于其大气氧化的信息。本文利用量子化学和化学动力学计算研究了 AP 在气相中的大气氧化机制，该机制是由其与 OH 自由基的反应引发的。该反应主要通过芳香环上的 OH 加成开始，预测的速率系数表明在大气中的寿命约为 8 天。加成形成加合物 AP-i-OH (Ri)（i = 1, 2, 3, 4，芳环上的位置）。加合物Ri会与O2反应或发生单分子分解。加合物R1与O2反应相当缓慢，有效速率系数<10−20cm3molecule−1s−1，并且会交替分解为苯酚和乙酰基。 R2、R3 和 R4 在与 O2 反应中的主要命运是通过直接夺取氢原子，形成羟基苯乙酮，并且只有 R3 会像烷基苯的氧化一样形成一小部分双环自由基。 AP氧化的主要产物包括苯酚和羟基苯乙酮的三种异构体，表明OH对AP的氧化可减少其对人体的不良影响。
Acetophenone (C8H8O, AP) is a common indoor air component but with no information on its atmospheric oxidation. The atmospheric oxidation mechanism of AP in gas phase, initiated by its reaction with the OH radical, is investigated here using quantum chemistry and chemical kinetics calculations. The reaction starts mainly by OH additions to the aromatic ring, and the predicted rate coefficient suggests a lifetime of ∼8 days in the atmosphere. The additions form adducts AP-i-OH (Ri) (i = 1, 2, 3, 4, the position on the aromatic ring). The adducts Ri would react with O2or undergo unimolecular decompositions. The adduct R1 reacts with O2rather slowly with an effective rate coefficients of <10−20cm3molecule−1s−1, and it would alternatively decompose to phenol and acetyl radical. The dominate fate of R2, R3, and R4 in their reaction with O2proceeds via direct hydrogen-atom abstraction, forming hydroxyacetophenones, and only R3 would have a fraction of bicyclic radical formation as in oxidation of alkyl benzenes. The main products from oxidation of AP include phenol and three isomers of hydroxyacetophenones, suggesting that oxidation of AP by OH would reduce its unpleasant effect to human beings.