物理化学学报 >> 2008, Vol. 24 >> Issue (11): 2053-2058.doi: 10.3866/PKU.WHXB20081120

研究论文 上一篇    下一篇

HCHO+X(X=F、Cl、Br)的反应机理

李晓艳; 曾艳丽; 孟令鹏; 郑世钧   

  1. 河北师范大学化学与材料科学学院, 计算量子化学研究所, 石家庄 050016
  • 收稿日期:2008-05-06 修回日期:2008-07-21 发布日期:2008-11-10
  • 通讯作者: 郑世钧 E-mail:sjzheng@mail.hebtu.edu.cn

Reaction Mechanisms of HCHO+X(X=F, Cl, Br)

LI Xiao-Yan; ZENG Yan-Li; MENG Ling-Peng; ZHENG Shi-Jun   

  1. Institute of Computational Quantum Chemistry, College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050016, P. R. China
  • Received:2008-05-06 Revised:2008-07-21 Published:2008-11-10
  • Contact: ZHENG Shi-Jun E-mail:sjzheng@mail.hebtu.edu.cn

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摘要： 采用CCSD/6-311++G(d,p)//B3LYP/6-311++G(d,p)方法研究了HCHO与卤素原子X(X=F、Cl、Br)的反应机理. 计算结果表明, 卤素原子X(X=F、Cl、Br)主要通过直接提取HCHO中的H原子生成HCO+HX(X=F、Cl、Br). 另外还可以生成稳定的中间体, 中间体再通过卤原子夺氢和氢原子直接解离两个反应通道分别生成HCO+HX(X=F、Cl、Br)和H+XCHO(X=F、Cl、Br). 其中卤原子夺氢通道为主反应通道, HCO和HX(X=F、Cl、Br)为主要的反应产物; 且三个反应的活化能均较低, 说明此类反应很容易进行, 计算结果与实验结果符合很好. 电子密度拓扑分析显示, 在HCHO+X反应通道(b)中出现了T型结构过渡态, 结构过渡态(STS)位于能量过渡态(ETS)之后. 并且按F、Cl、Br的顺序, 结构过渡态出现得越来越晚.

关键词: 大气污染, HCHO, 电子密度拓扑分析, T-型结构过渡态

Abstract: The reactions of HCHO+X (X=F, Cl, Br) were studied at CCSD/6-311++G(d,p)//B3LYP/6-311++G (d,p) level. The computational results show that the reaction channel of halogen atom X (X=F, Cl, Br) which gains H atom of the HCHOto get HCO+HX(X=F, Cl, Br) is the main reaction channel. Except this reaction channel, a stable complex forms firstly, then the complex via two channels to get the products, one is that the halogen atom gains a hydrogen from HCHO to form HCO+HX(X=F, Cl, Br) and the other is that the complex decomposes directly to H and XCHO (X=F, Cl, Br). The first channel is the main channel and the HCO+HX(X=F, Cl, Br) are the main products. Furthermore, because the energy barriers of the three reactions are low, these reactions could occur easily. The topological analysis of electron density shows that there is a T-shape structure transition state (STS) in the channel (b) of HCHO+X reaction, the STS appears later than the energy transition state (ETS). And the STS appears later and later in the sequence of F, Cl, Br.

Key words: Air pollution, HCHO, Topological analysis of electron density, T-shape structure transition state

MSC2000: 

  • O641