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化学学报
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化学学报 ›› 2009, Vol. 67 ›› Issue (17): 1987-1994. 上一篇    下一篇

研究论文

CH2SH与NO2双自由基反应机理的理论研究

辛景凡a 王文亮*,a 王渭娜a 张 越a 吕 剑b

  

  1. (a陕西省大分子科学重点实验室 陕西师范大学化学与材料科学学院 西安 710062)
    (b西安近代化学研究所 西安 710065)

  • 投稿日期:2008-10-09 修回日期:2009-03-02 发布日期:2009-09-14
  • 通讯作者: 王文亮

Theoretical Study on the Biradical Reaction Mechanism of CH2SH with NO2

Xin, Jingfana Wang, Wenliang*,a Wang, Weinaa Zhang, Yuea Lü, Jianb

  

  1. (a Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi’an 710062)
    (b Xi’an Modern Chemistry Research Institute, Xi’an 710065)
  • Received:2008-10-09 Revised:2009-03-02 Published:2009-09-14
  • Contact: WANG Wen-Liang

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在B3LYP/6-311＋＋G(2df,p)水平上优化了标题反应驻点物种的几何构型, 并在相同水平上通过频率计算和内禀反应坐标(IRC)分析对过渡态结构及连接性进行了验证. 采用双水平计算方法HL//B3LYP/6-311＋＋G(2df,p)对所有驻点及部分选择点进行了单点能校正, 构建了CH2SH＋NO2反应体系的单重态反应势能剖面. 研究结果表明, CH2SH与NO2反应体系存在4条主要反应通道, 两个自由基中的C与N首先进行单重态耦合, 形成稳定的中间体HSCH2NO2 (a). 中间体a经过C—N键断裂和H(1)—O(2)形成过程生成主要产物P1 (CH2S＋trans-HONO), 此过程需克服124.1 kJ•mol－1的能垒. 中间体a也可以经过C—N键断裂及C—O键形成转化为中间体HSCH2ONO (b), 此过程的能垒高达238.34 kJ•mol－1. b再经过一系列的重排异构转化得到产物P2 (CH2S＋cis-HONO), P3 (CH2S＋HNO2)和P4 (SCH2OH＋NO). 所有通道均为放热反应, 反应能分别为－150.37, －148.53, －114.42和－131.56 kJ•mol－1. 标题反应主通道R→a→TSa/P1→P1的表观活化能为－91.82 kJ•mol－1, 此通道在200～3000 K温度区间内表观反应速率常数三参数表达式为kCVT/SCT＝8.3×10－40T4.4 exp(12789.3/T) cm3•molecule－1•s－1.

关键词: CH2SH, NO2, 密度泛函理论, 反应机理, 速率常数

The mechanism for the reaction CH2SH with NO2 was investigated at the HL//B3LYP/6-311＋＋G(2df,p) level on single potential energy surface. All stationary points involved in the title reaction were calculated at the B3LYP/6-311＋＋G(2df,p) level. Frequency calculation and intrinsic reaction coordinate (IRC) analysis at the same level were applied to validation of the connection of transition states. The results show that CH2SH＋NO2 system has four dominating reaction channels. Firstly, CH2SH and NO2 take the carbon-to-nitrogen approach forming an adduct HSCH2NO2 (a), followed by C—N bond rupture along with H(1)—O(2) bond formation leading to the major product P1 (CH2S＋trans-HONO). This process with a barrier height of 124.1 kJ•mol－1. HSCH2NO2 (a) can undergo the C—O bond formation along with C—N bond rupture to HSCH2ONO (b), and the barrier height is exceedingly high, 238.34 kJ•mol－1. b will take subsequent conversion and dissociation to products P2 (CH2S＋cis-HONO), P3 (CH2S＋HNO2) and P4 (SCH2OH＋NO). All the channels are exothermic reactions and the reaction energy of generation is －150.37, －148.53, －114.42 and －131.56 kJ•mol－1, respectively. The channel R→a→TSa/P1→P1 is the major channel for the reaction of CH2SH with NO2. Apparent activation energy for the major channel is －91.82 kJ•mol－1. The fitted three-parameter expression for the major channel (R→a→TSa/P1→P1) is kCVT/SCT＝8.3×10－40T4.4exp(12789.3/T) in the temperature range of 200～3000 K, in which k takes unit of cm3•molecule－1•s－1.

Key words: CH2SH, NO2, density functional theory (DFT), reaction mechanism, rate constant

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