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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Reactivity of the CF_3CFHO Radical: Thermal Decomposition and Reaction with O_2
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Reactivity of the CF_3CFHO Radical: Thermal Decomposition and Reaction with O_2

机译：CF_3CFHO自由基的反应活性：热分解和与O_2的反应

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The kinetics of CF_3CFHO radical reactions was studied at 20 and 35 Torr and from 259 to 297 K by flash photolysis with time-resolved mass spectrometry. The CF_3CFHO_2 radical was generated by flash photolysis of Cl_2 in the presence of CF_3CFH_2 and O_2, and CF_3CFHO was formed by the reaction of CF_3CFHO_2 with Cl and by the peroxy radical self-reaction. The rate coefficient ratio for (1) CF_3CFHO + O_2 → CF_3C(O)F + HO_2 and (2) CF_3CFHO HC(O)F + CF_3 was determined by observing the formation of HC(O)F as a function of the partial pressure of O_2. At 20 Torr, k_1/k_2 = (2.4 ± 0.8) * 10~(-25) e~((4248±550)/T) cm~3 molecule~(-1), and at 35 Torr, k_1/k_2 = (9.1 ± 3.3) * 10~(-26) e~((4370±500)/T) cm~3 molecule~(-1). Ab initio molecular orbital calculations for optimized geometries, vibrational frequencies, and total energies of CF_3CFHO, the reaction products, and the C-C bond-breaking transition state were made. Energies were calculated by the G2 and G2(MP2) methods. An RRKM model for reaction 2 was based on geometries and energies from the ab initio calculations. RRKM calculated values of k_2 were combined with the experimentally determined k_1/k_2 to estimate k1. Comparisons were made with estimates made with two other RRKM models (Schneider, W. F.; Wallington, T. J.; Barker, J. R.; Stahlberg, E. A. Ber. Bunsen-Ges. Phys. Chem. 1998, 102, 1850; Somnitz, H.; Zellner, R. Phys. Chem. Chem. Phys. 2001, 3, 2352). The ab initio calculations predict the 298 K enthalpy of formation of CF_3CFHO to be -203.0 kcal mol~(-1) (G2MP2) and -203.4 kcal mol~(-1) (G2).
机译：CF_3CFHO自由基反应的动力学是在20和35 Torr以及从259至297 K的条件下通过快速光解和时间分辨质谱法研究的。 CF_3CFHO_2和O_2的存在下，Cl_2的快速光解产生了CF_3CFHO_2自由基，CF_3CFHO_2与Cl的反应以及过氧自由基的自反应形成了CF_3CFHO。通过观察HC（O）F的形成与分压的关系来确定（1）CF_3CFHO + O_2→CF_3C（O）F + HO_2和（2）CF_3CFHO HC（O）F + CF_3的速率系数比的O_2。在20托时，k_1 / k_2 =（2.4±0.8）* 10〜（-25）e〜（（4248±550）/ T）cm〜3分子〜（-1），在35托时，k_1 / k_2 = （9.1±3.3）* 10〜（-26）e〜（（4370±500）/ T）cm〜3分子〜（-1）。从头算分子轨道计算优化了CF_3CFHO的几何形状，振动频率和总能量，反应产物以及C-C键断裂的过渡态。通过G2和G2（MP2）方法计算能量。反应2的RRKM模型基于从头算的几何形状和能量。将k_2的RRKM计算值与实验确定的k_1 / k_2相结合，以估计k1。比较并与其他两种RRKM模型（Schneider，WF; Wallington，TJ; Barker，JR; Stahlberg，EA Ber.Bunsen-Ges.Phys.Chem.1998，102，1850; Somnitz，H .; Zellner， R.Phys.Chem.Chem.Phys.2001，3，2352）。从头算可以预测CF_3CFHO形成的298 K焓为-203.0 kcal mol〜（-1）（G2MP2）和-203.4 kcal mol〜（-1）（G2）。

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