CX_2(X=F,Cl,Br)与CH_3CHO中C-C键插入和环加成的理论模拟

Quantum Chemical and Topological Study on the C-C Bond Insertion and Cycloaddition Reaction Mechanism of CX_2 (X=F,Cl,Br) with Acetaldehyde

采用密度泛函[DFT]和自然键轨道理论[NBO]及高级电子耦合簇[CCSD(T)]和电子密度拓扑分析[AIM]方法,研究了单重态二卤卡宾CX_2(x=F,Cl,Br)与乙醛CH_3CHO中C-C键的插入反应及其环加成的反应机理.在B3LYP/6-31G(d)水平上优化了各驻点构型,用频率分析和内禀反应坐标法(IRC)对过渡态进行了验证,计算了各物种的CCSD(T)/6-31G(d,p)单点能量.用经Wigner校正的Eyring过渡态理论分别计算了1大气压下主反应通道的热力学与动力学性质,并对反应通道中构型进行了自然键轨道及电子密度拓扑分析.结果表明,CF_2与CH_3CHO反应的主产物是P2_F[CH_3CF-2CHO:插入CH_3CHO中C-C键,反应Ⅰ(2)],而CCI_2及CBr_2与CH_3CHO反应的主产物是P1_cl[Cl_2COCHCH_3:成环反应Ⅱ(1)]及P1 B[Br_2COCHCH_3:成环反应Ⅲ(1)],1大气压下,反应I(2)和Ⅱ(1)及Ⅲ(1)进行的适宜温度范围分别为400～1300 K和400～1000 K.

The C-C bond insertion and cycloaddition reaction mechanism of CX2 with CH3 CHO have been studied by using the B3LYP/6-31G （d） method. The geometries of reactions, transition state and products were completely optimized. All the energy of the species was obtained at the CCSD（T）/6-31G（d, p） level. All the transition state is verified by the vibrational analysis and the internal reaction coordinate （IRC） calculations. The statistical thermodynamics and Eyring transition state theory with Wigner correction are used to study the thermodynamic and kinetic characters of the insertion and cycloaddition reaction at 1.0 Atm. The topological and natural bond orbital characters of complexes are studied. The results show that main product of CF2 ＋ CH3CHO is P2F [CH3CF2CHO： insertion of C-C bond of CH3CHO,reaction I （2）1 and products of P1CIECl2COCHCH3：cycloaddition reaction II （1）-1 and P1Br [Br2COCHCH3 ：cycloaddition reaction III （1）] are obtained being the reactions occurred between CC12 and CH3CHO,also between CBr2 and CH3CHO. The appropriate reaction temperature range is 400 to 1300 K and 400 to 1000 K at 1.0 atm for I （2） ,and II （1）, III （1） respectively.