氟代次甲基与氧气的反应机理研究

在B3LYP/6-311G(d,p)水平上研究了CF自由基与O2反应的微观机理.对反应势能面上的各反应物、过渡态、中间体和产物的几何结构进行了全参数优化,且在QCISD/6-311G(d,p)水平上计算了它们的能量.研究发现CF+O2反应在高温过程中重要,有3个产物通道,即F+CO2、FCO+O和FO+CO,其中最有竞争力的通道为F+CO2,其次为FCO+O通道,FO+CO通道可能难发生.与CH+O2反应比较发现两者有相似的地方,如第一步都是CX(X=H或F)自由基进攻O2分子中的一个氧原子形成链状过氧化物XCOO.两反应机理也存在很多不同之处,如HCO+O和FCO+O通道的形成过程有很大的不同;两反应速率也相差较大.CH+O2反应快,CF+O2反应慢.

Study on the reaction mechanism of the CF radical with O2

The mechanism of the reaction of the CF radical with O2 was studied theoretically at the B3LYP/6-311G（d,p） level.All structures of reactants,intermediates,transition states and products were optimized.The QCISD/6-311G（d,p） single point calculations were performed using the B3LYP/6-311G（d,p） optimized geometries to accurately determine the energetics.The title reaction was found to be important in a high temperature process.Three product channels,F ＋ CO2,FCO ＋ O and FO ＋ CO,have been found.The most competitive channel was F ＋ CO2,the second competitive one was FCO ＋ O.The formation of FO ＋ CO was probably difficult.In comparison with the reaction of CH ＋ O2,there were some similarities between the two reactions.For instance,the first steps of the both reactions were the attacks of CX（X = H or F） radical on one oxygen atom of the oxygen molecule,forming the chain-like peroxide XCOO.There were also some discrepancies between them.The formation processes of HCO＋O and FCO＋O were different;their reaction rates were different as well,the CH＋O2 reaction was faster than CF＋O2.