【作者】 宋贵彩；

【导师】 潘秀梅；

【作者基本信息】 东北师范大学 ， 物理化学， 2011， 硕士

【摘要】 氢氟醚（HFEs）已被作为全氯氟烷（CFCs）的第三代替代物在诸多工业领域得到广泛应用。然而,有些氢氟醚可能存在造成温室效应的潜力,因此,为了更好地了解氢氟醚对大气环境的影响,确定它们在同温层中的寿命是必要的。深入研究氢氟醚在大气中的反应机理及其动力学行为,揭示它们的大气寿命及其对环境潜在的影响,对控制环境污染方面有着重要意义。本论文利用量子化学理论,分别对三种氢氟醚（CH₂FCF₂OCHF₂, CH₂FOCH₂F,CF₃CH₂OCH₃）与活泼OH自由基反应在反应势能面及反应动力学性质计算两个方面进行了研究。这些反应为: CH₂FCF₂OCHF₂ + OH→products CH₂FOCH₂F + OH→products CF₃CH₂OCH₃ + OH→products本论文的主要内容概括如下:1. CH₂FCF₂OCHF₂/CH₂FOCH₂F与OH自由基反应的反应机制及动力学性质研究。在B3LYP/6-311G（d,p）,BH&H-LYP/6-311G（d,p）和MP2（full）/6-311G（d,p）水平下,研究了两反应相关势能面信息（各稳定点的几何构型、振动频率和单点能等）,反应焓和反应吉布斯自由能等热力学性质及反应速率常数和分支比等动力学性质。并利用同构反应,理论上估算了CH₂FCF₂OCHF₂, CHFCF₂OCHF₂, CH₂FCF₂OCF₂, CH₂FOCH₂F和CHFOCH₂F自由基的标准生成焓。结合小曲率隧道效应校正的正则变分过渡态速率常数（CVT/SCT）与相应的可利用的文献值相吻合。220-2000K温度范围内的速率常数计算结果表明,两反应体系的速率常数都是正温度效应。两个反应速率的三参数Arrheniun表达式分别为(单位:cm³ molecule^-1 s^-1): k₁ = 1.62×10^-20 T^2.75 exp（-1011/T）; k₂ = 3.40×10^-21 T^3.04 exp（-384/T）。2. CF₃CH₂OCH₃与OH自由基反应的反应机制及热力学性质研究。在MP2/6-311G（d,p）和BH&H-LYP/6-311G（d,p）水平下,研究了各稳定点的几何构型、振动频率及基于结构信息在BMC-CCSD和BMC-QCISD水平下的稳定点的单点能校正。另外,在相同计算水平下计算了反应体系的反应焓和反应吉布斯自由能,在BMC-CCSD//MP2/6-311G（d,p）水平下计算了CF₃CH₂OCH₃,CF₃CHOCH₃和CF₃CH₂OCH₂)的标准生成焓等热力学性质。更多还原

【Abstract】 Hydrofluoroethers （HFEs） have been the third generation alternatuvel compounds to CFCs and are used in various industrial applications. However, they may be evaluated as possible greenhouse gases because of absorption in the terrestrial infrared radiation. So assessing its atmospheric chemistry and environmental impact is necessary by determining its atmospheric lifetime. Detailed investigations on the reaction mechanisms and kinetics of HFEs are very important to control atmospheric pollutions.By the quantum chemistry theory, the mechanisms and dynamics studies of reactions of CH₂FCF₂OCHF₂/ CH₂FOCH₂F/CF₃CH₂OCH₃ + OH have been carried out theoretically. These reactions are described as: CH₂FCF₂OCHF₂ + OH→products CH₂FOCH₂F + OH→products CF₃CH₂OCH₃ + OH→productsThe important and valuable results in this work are summarized as follows:1. Theoretical Studies on the Mechanisms and Dynamics of OH Radicals with CH₂FCF₂OCHF₂ and CH₂FOCH₂F. The geometries, frequencies of all the stationary points were carried out at the B3LYP/6-311G（d,p）, BH&H-LYP/6-311G（d,p） and MP2（full）/6-311G（d,p） levels. In this work we studied the potential energy surface information（including optimized geometries, harmonic vibrational frequencies and the single-point energy calculations of the stationary points）, the reaction enthalpies (ΔH _r,298⁰ ) and reaction gibbs free energiesΔG_r,298⁰ . Also, the heoretical prediction of the rate constants, the temperature dependence of branching ratios are provided. Moreover, standard enthalpies of formation of CH₂FCF₂OCHF₂,CHFCF₂OCHF₂,CH₂FCF₂OCF₂,CH₂FOCH₂F和CHFOCH₂F radical are estimated theoretically using group-balanced isodesmic reactions. The rate constants calculated by canonical variational transition state theory with small-curvature tunneling （CVT/SCT） correction are consistent with the available experimental values. The result of rate constant calculations in over the temperature range of 220-2000K show that the rate constants of two reactions have positive temperature dependence. The three-parameter Arrhenius expressions are as follows (in units of cm3 molecule^-1 s^-1): k₁ = 1.62×10^-20 T^2.75 exp（^-1011/T）; k₂ = 3.40×10^-（21） T^3.04 exp（-384/T）。2. Theoretical Studies on the Potential Energy Surfaces and Thermodynamics of CF₃CH₂OCH₃ with Radicals. The geometries, frequencies of all the stationary points were carried out at the MP2/6-311G（d,p） and BH&H-LYP/6-311G（d,p） levels. The single-point energy calculations for the stationary points were carried out at BMC-CCSD andBMC-QCISD level by using the MP2/6-311G（d,p） and BH&H-LYP/6-311G（d,p） optimized geometries. Moreover, the reaction enthalpies (ΔH _r,298⁰ ), reaction gibbs free energiesΔG_r,298⁰ , and standard enthalpies of formation of CF₃CH₂OCH₃, CF₃CHOCH₃ and CF₃CH₂OCH₂ estimated theoretically using group-balanced isodesmic reactions carried out at several different levels.更多还原