高等学校化学学报

高等学校化学学报

• 研究论文 • 上一篇    下一篇

CH4-nFn(n=1～3)与CH3氢抽提反应微观动力学的理论研究

冯丽霞1, 王文亮1, 李琳1, 王渭娜1, 罗琼1,2, 李前树1,2
   

    1. 陕西师范大学化学与材料科学学院, 西安 710062;
    2. 北京理工大学理学院, 北京 100081
  • 收稿日期:2005-08-25 修回日期:1900-01-01 出版日期:2006-09-10 发布日期:2006-09-10
  • 通讯作者: 王文亮

Micro-dynamics of Hydrogen Abstraction Reaction Between CH4-nFn(n=1—3) and CH3

FENG Li-Xia1, WANG Wen-Liang1, LI Lin1, WANG Wei-Na1, LUO Qiong1,2, LI Qian-Shu1,2
   

    1. School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an 710062, China;
    2. School of Science, Beijing Institute of Technology, Beijing 100081, China
  • Received:2005-08-25 Revised:1900-01-01 Online:2006-09-10 Published:2006-09-10
  • Contact: WANG Wen-Liang

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摘要： 采用量子化学的QCISD(T)/6-311+G(d,p)//BHandHLYP/6-311G(d,p)方法研究了氟代甲烷H4-nFn(n=1~3)与CH3自由基氢抽提反应的微观动力学性质. 并利用Polyrate程序分别计算了3个反应在200~3 000 K范围内的速率常数. 计算结果表明, R1a, R2a和R3三个反应路径的反应能量分别为-12.7, -9.5和11.8 kJ/mol, 相应的能垒依次为67.0, 62.2和67.5 kJ/mol. 在437 K时, kCVT/SCT分别为6.72×10-19, 8.01×10-18和8.82×10-20 cm3/(molecule·s). 计算结果还表明, 在低温段反应的量子隧道效应显著, 在计算温度范围内变分效应对反应速率常数的影响可以忽略.

关键词: H4-nFn(n=1~3), 氢抽提反应, QCISD(T)//BHandHLYP, 速率常数

Abstract: QCISD(T)/6-311+G(d,p)//BHandHLYP/6-311G(d,p) method was employed to reveal the reaction mechanism and to predict the micro-kinetic character of the hydrogen abstraction reactions of H4-nFn(n=1~3) with CH3. The rate constants of the reactions were evaluated by means of the canonical variational transition-state theory(CVT) conjunction with small-curvature tunneling(SCT) correction in the temperature range of 200—3 000 K. In this study, the reaction energies ΔE of R1a, R2a and R3 are -12.7, -9.5 and 11.8 kJ/mol, the potential barriers ΔE≠ were 67.0, 62.2 and 67.5 kJ/mol, respectively. At 437 K, the CVT/SCT rate constants were 6.72×10-19, 8.01×10-18 and 8.82×10-20 cm3/(molecule·s), which were in agreement with the experimental values 3.31×10-19, 1.05×10-18 and 8.33×10-20 cm3/(molecule·s). The results indicate that the tunneling effect was considerable at the lower temperatures, while the variational effect was almost negligible in the entire process.

Key words: H4-nFn(n=1~3), H-abstraction reaction, QCISD(T)//BHandHLYP, Rate constant

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