硝酸异丙酯与Cl原子、 OH和NO3自由基反应的机理及动力学

采用CCSD(T)//M06-2X/6-311++G(d,p)方法, 结合传统过渡态理论, 研究了硝酸异丙酯与Cl原子、 OH及NO₃自由基的反应机理和动力学. 两个反应物单体首先形成氢键复合物, 随后X(X=Cl原子、 OH和NO₃自由基)提取硝酸异丙酯中叔碳的α-H原子或甲基的β-H原子, 室温下, 以X提取α-H原子为主. 反应的主要历程为 Cl原子(OH或NO₃自由基)提取(CH₃)₂CHONO₂的α-H原子, 生成HCl(H₂O或HNO₃)分子和(CH₃)₂CONO₂自由基, 后者分解为丙酮和NO₂. 结果表明, 在200~500 K温度范围内, 随着温度的升高, 丙酮和NO₂的产率降低; 在室温下, 硝酸异丙酯与Cl原子、 OH和NO₃自由基反应的速率常数分别为3.933×10^-11, 1.182×10^-13和7.134×10^-19 cm³·molecule^-1·s^-1. 计算所得硝酸异丙酯与OH自由基反应的动力学数据与实验结论一致.

Mechanism and Kinetics on the Reaction of Isopropyl Nitrate with Cl,OH and NO3 Radicals

The reaction mechanism of （CH₃）₂CHONO₂ with X（X=Cl， OH and NO₃ radical） was studied at M06-2X/ 6-311++G（d，p） level of theory， and the energy of the stationary points was calculated by CCSD（T） method. The kinetics of the reaction was calculated by the conventional transition state theory. The hydrogen bonded complexes are formed firstly by isopropyl nitrate and X radical， and X radical can abstract the α-H or β-H atoms from （CH₃）₂CHONO₂. The α-H abstraction is the main channel， and the main products are （CH₃）₂CO + NO₂ + HCl（H₂O or HNO₃）. The yield of α-H abstraction products decreases as the temperature increases from 200 K to 500 K for IPN + OH reaction. The overall rate constant for the reaction of （CH₃）₂CHONO₂ with Cl atom， OH and NO₃ radical at 300 K is 3.933×10^-11， 1.182×10^-13， and 7.134×10^-19 cm³·molecule^-1·s^-1， respectively. The theoretical kinetics data is in consistent with the previous experimental values for the reaction of OH with isopropyl nitrate.