Atmospheric Gas Phase Chemistry of CH2鈺怤H and HNC. A First-Principles Approach

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• 作者：Arne Joakim C. Bunkan ; Yizhen Tang ; Stig R. Sellev氓g ; Claus J. Nielsen
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：July 17, 2014
• 年：2014
• 卷：118
• 期：28
• 页码：5279-5288
• 全文大小：496K
• ISSN：1520-5215

文摘

Quantum chemical methods were used to investigate the OH initiated atmospheric degradation of methanimine, CH₂鈺怤H, the major primary product in the atmospheric photo-oxidation of methylamine, CH₃NH₂. Energies of stationary points on potential energy surfaces of reaction were calculated using multireference perturbation theory and coupled cluster theory. The results show that hydrogen abstraction dominates over the addition route in the CH₂鈺怤H + OH reaction, and that the major primary product is HCN, while HNC and CHONH₂ are minor primary products. HNC is found to react with OH exclusively via addition to the carbon atom followed by O鈥揌 scission leading to HNCO; N₂O is not a product in the atmospheric photo-oxidation of HNC. Additional G4 calculations of the CH₂鈺怤H + O₃ reaction show that this is too slow to be of importance at atmospheric conditions. Rate coefficients for the CH₂鈺怤H + OH and HNC + OH reactions were calculated as a function of temperature and pressure using a master equation model based on the coupled cluster theory results. The rate coefficients for OH reaction with CH₂鈺怤H and HNC at 1000 mbar and room temperature are calculated to be 3.0 脳 10^鈥?2 and 1.3 脳 10^鈥?1 cm³ molecule^鈥? s^鈥?, respectively. The atmospheric fate of CH₂鈺怤H is discussed and a gas phase photo-oxidation mechanism is presented.