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

吡唑衍生物与碘甲烷反应的密度泛函理论研究

沈福刚, 段文勇, 孙宏伟, 陈兰, 陈沛全, 赖城明, 李正名   

  1. 南开大学化学学院, 天津 300071
  • 收稿日期:2005-09-28 修回日期:1900-01-01 出版日期:2006-11-10 发布日期:2006-11-10
  • 通讯作者: 孙宏伟

Density Functional Theory Study on the Reactions of Pyrazole Derivatives with CH3I

SHEN Fu-Gang, DUAN Wen-Yong, SUN Hong-Wei, CHEN Lan, CHEN Pei-Quan, LAI Cheng-Ming, LI Zheng-Ming   

  1. College of Chemistry, Nankai University, Tianjin 300071, China
  • Received:2005-09-28 Revised:1900-01-01 Online:2006-11-10 Published:2006-11-10

PDF (PC)

摘要： 采用密度泛函方法对3-甲硫基-4-氰基-5-氨基吡唑与碘甲烷反应的机理进行了研究. 提出了两种可能的反应途径: 反应途径Ⅰ为反应物先脱去吡唑上的质子, 生成阴离子中间物, 然后碘甲烷分别进攻中间物吡唑环上的2个氮原子, 生成两种异构产物; 反应途径Ⅱ为反应物通过分子间氢转移存在两种异构体, 碘甲烷直接进攻每个异构反应物吡唑上的氮原子, 形成中间物, 然后脱去碘化氢, 生成产物. 计算结果表明, 途径Ⅱ应为主要反应途径. 还找出了两种异构产物间甲基迁移反应的过渡态, 得出该反应的活化能为278.5 kJ/mol, 在常温下甲基迁移反应不容易进行.

关键词: 密度泛函理论, 过渡态, 吡唑衍生物, 反应途径

Abstract: Density functional(B3LYP) calculations, using the 6-31G* and LANL2DZdp ECP Polarization basis sets, were employed to study the reaction pathway involving 3-methylthio-4-cyano-pyrazole and iodomethane. According to the structure of pyrazole derivatives, two possible reaction pathways were examined. Pathway Ⅰ proceeded associated with the dehydrogenation of the reactants and the attack of CH3I on both nitrogen atoms of pyrazole. Pathway Ⅱ was as follows: first, due to the hydrogen transfer of the reactants, two isomers are formed; then CH3I attacks on nitrogen atom of the isomers to form intermediates; finally the intermediates dehydroiodinate to form two products. The results from the calculation suggest that pathway Ⅱ is the dominant reaction channel.

Key words: Density functional theory, Transition state, Pyrazole derivatives, Reaction pathway

中图分类号: 

TrendMD: