Computational studies on the gas phase reaction of methylenimine (CH2NH) with water molecules
Computational studies on the gas phase reaction of methylenimine (CH2NH) with water molecules
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DOI：
10.1038/s41598-020-67515-3
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发表时间：
2020-07-03
影响因子：
4.6
通讯作者：
Ali, Mohamad Akbar
中科院分区：
文献类型：
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作者：
Ali, Mohamad Akbar
本文采用量子化学方法和化学动力学模型来回答亚甲亚胺（CH2NH）气相水化反应是否能生成甲醛（CH2O）和氨（NH3）的问题。采用CCSD(T)/ /M06-2X/6-311++G（3d,3pd）水平计算了CH2NH + H2O -> CH2O ->+NH3和CH2NH + 2H(2)O -> CH2O ->+NH3 + H2O反应的势能面（PESs）。采用变分跃迁态理论（VTST）、微正则变分跃迁态理论（mu VTST）和Rice-Ramsperger-Kassel-Marcus/master方程（RRKM/ME）模拟计算温度和压力相关的速率常数。沿反应路径形成弱结合络合物（CH2NH中心点中心点中心点中心点H2O）的PES采用VTST和mu VTST进行定位，而沿紧过渡态的PES采用小曲率隧穿（SCT）方法进行表征。结果表明，CH2NH + H2O ->的形成与压力和温度有关。计算得到的CH2NH -> H2O的大气寿命（约为8分钟）太短，无法与其他大气物质发生二次双分子反应。我们的研究结果表明，ch2o和nh -3的形成可能发生在生物质燃烧的燃烧过程中，但在大气条件下，ch2o和nh -3的形成速度可以忽略不计。当第二个水分子加入到反应中，结果表明ch2o和nh -3的生成速率仍然可以忽略不计。
In this work, we used quantum chemical methods and chemical kinetic models to answer the question of whether or not formaldehyde (CH2O) and ammonia-(NH3) can be produced from gas phase hydration of methylenimine (CH2NH). The potential energy surfaces (PESs) of C H2NH + H2O -> CH2O ->+NH3 and CH2NH + 2H(2)O -> CH2O ->+NH3 + H2O reactions were computed using CCSD(T)/6-311++G(3d,3pd)//M06-2X/6-311++G(3d,3pd) level. The temperature-and pressure-dependent rate constants were calculated using variational transition state theory (VTST), microcanonical variational transition state theory (mu VTST) and Rice-Ramsperger-Kassel-Marcus/master equation (RRKM/ME) simulations. The PES along the reaction path forming a weakly bound complex (CH2NH center dot center dot center dot H2O) was located using VTST and mu VTST, however, the PES along the tight transition state was characterized by VTST with small curvature tunneling (SCT) approach. The results show that the formation of CH2NH + H2O -> CH2NH -> H2O is pressure -and temperature-dependent. The calculated atmospheric lifetimes of CH2NH -> H2O (similar to 8 min) are too short to undergo secondary bimolecular reactions with other atmospheric species. Our results suggest that the formation of C H2O and N H-3 likely to occur in the combustion of biomass burning but the rate of formation C H2O and N H-3 is predicted to be negligible under atmospheric conditions. When a second water molecule is added to the reaction, the results suggest that the rates of formation of C H2O and N H-3 remain negligible.