物理化学学报 >> 2004, Vol. 20 >> Issue (03): 228-232.doi: 10.3866/PKU.WHXB20040302

研究论文 上一篇    下一篇

CH3+HNCO反应机理的理论研究

李来才;钱一鸣;朱元强;田安民   

  1. 四川师范大学化学系,成都 610066; 四川大学化学学院,成都 610064
  • 收稿日期:2003-07-10 修回日期:2003-10-19 发布日期:2004-03-15
  • 通讯作者: 李来才 E-mail:liline33@sohu.com

Theoretical Study on the Reaction Mechanism of the CH3 Radical with HNCO

Li Lai-Cai;Qian Yi-Ming;Zhu Yuan-Qiang;Tian An-Min   

  1. Department of Chemistry, Sichuan Normal University, Chengdu 610066;Department of Chemistry, Sichuan University, Chengdu 610064
  • Received:2003-07-10 Revised:2003-10-19 Published:2004-03-15
  • Contact: Li Lai-Cai E-mail:liline33@sohu.com

摘要: 在6-311++G**基组水平上,采用UMP2方法对自由基CH3与HNCO反应机理进行了研究,全参数优化了反应通道上各驻点的几何构型.结果表明, 自由基CH3与HNCO分子间反应有三条反应通道,第一为CH3与HNCO分子间经过生成一个稳定化能为4.56 kJ•mol-1的含氢键的分子复合物M后,经过渡态TS生成另一个产物复合物M′,然后分解为甲烷和NCO自由基;第二是CH3与HNCO分子间通过生成稳定反式中间体trans-int,其经过渡态trans-ts分解成产物CH3NH和CO;第三是CH3与HNCO分子间通过生成稳定顺式中间体cis-int,其经过渡态cis-ts分解成产物CH3NH和CO.比较三条反应通道的反应活化能,表明CH3与HNCO反应较易生成CH4+NCO.

关键词: 异氰酸, 自由基反应, 从头算方法, 氢键复合物

Abstract: Ab initio UMP2 method was used to study the reaction mechanism of CH3 radical with HNCO. The geometric configurations of reactants, products, intermediates and transition states were optimized at UMP2(full)/6-311++G** level. The results show that the reaction of CH3 radical with HNCO has three pathways: (1) CH3 radical reacts with HNCO to form a hydrogen-bond complex M of which the relative stable energy is 4.56 kJ•mol-1,and then forms another complex M′through a transition state TS, and breaks down into CH4 and NCO radical in the end. (2) CH3 radical reacts with HNCO to form a stable trans- intermediate (trans-int), then through a transition state (trans-ts) breaks down into CH3NH and CO. (3) CH3 radical reacts with HNCO to form a stable cis-intermediate (cis-int), and then through a transition state(cis-ts) breaks down into CH3NH and CO. Comparing the activation energy of the three pathways, we can draw a conclusion that the pathway of forming CH4 and NCO radical is more feasible.

Key words: HNCO, Radical reaction, Ab initio UMP2 method, Hydrogen-bond complex