Gas-phase reaction of hydroxyl radical with hexamethylbenzene.
Gas-phase reaction of hydroxyl radical with hexamethylbenzene.
复制标题
羟基自由基与六甲苯的气相反应。
DOI：
10.1021/jp307568c
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
E. Villenave
中科院分区：
文献类型：
--
作者：
J. Loison;M. Rayez;J. Rayez;A. Gratien;Pranay P. Morajkar;C. Fittschen;E. Villenave
芳香烃是受污染环境空气的重要成分。羟基自由基与六甲苯(HMB)的反应是研究IPSO加成最终导致脱烷基化反应的一个原型系统。我们用放电快流反应器和单光子真空紫外光电离飞行时间质谱仪(10.54 eV)耦合，研究了323~433K之间的OH+HMB和OD+HMB反应。在330K时，氢原子吸收通道为(13.7±4.4)%，在298K时为(11.1±3.6)%，高于常用的结构-反应性关系式。测定了反解离速率常数，发现该速率常数小于其他芳香烃的速率，与密度泛函理论计算符合较好。生成五甲基苯酚(PMP)+CH(3)的脱烷基通道一直被认为是次要通道，在298K时估计低于2%。
Aromatic hydrocarbons are important components of polluted ambient air. The reaction of OH radicals with hexamethylbenzene (HMB) is a prototype system to study ipso addition leading eventually to dealkylation. We have investigated the OH + HMB and OD + HMB reactions between 323 and 433 K using a discharge fast-flow reactor coupled to a time-of-flight mass spectrometer with single-photon VUV photoionization (10.54 eV). The H atom abstraction channel has been found to be equal to (13.7 ± 4.4) % at 330 K leading to (11.1 ± 3.6) % at 298 K, higher than predicted by commonly used structure-reactivity relationships. The back dissociation rate constant has also been measured and has been found to be smaller than the rate of other aromatic hydrocarbons, in good agreement with density functional theoretical calculations. The dealkylation channel, leading to pentamethylphenol (PMP) + CH(3), is always found to be the minor channel, estimated inferior to 2% at 298 K.