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采用密度泛函理论在B3LYP/6-31G(d)水平上研究了卡宾CH2及二溴卡宾CBr2与乙醛CH3CHO中C—H键的插入反应机理,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)及CCSD(T)/6-31G(d,p)单点能量.结果表明,CH2与CH3CHO插入反应主产物为丙醛(HP1),而CBr2与CH3CHO插入反应的两条主反应通道都在单重态势能面中,单重态CBr2既可以发生与Cα—H键的插入反应Ⅰ(1),也可以发生与Cβ—H键插入的反应Ⅱ(1).用经Wigner校正的Eyring过渡态理论分别计算了反应Ⅰ(1)及Ⅱ(1)在100～2200K温度范围内的热力学与动力学性质.在101325Pa下,反应Ⅰ(1)及Ⅱ(1)进行的适宜温度范围分别为250～1750及250～1600K.在250～1000K的温度范围内,反应Ⅰ(1)与其竞争反应Ⅱ(1)的反应速率及平衡转化率差别很大,具有很好的选择性,更有利于二溴卡宾插入乙醛Cα—H键生成产物P1的反应Ⅰ(1)的发生,而在1000～1600K范围内,反应没有明显的选择优势.
The mechanism of C-H bond insertion between carbenoxime CH2 and dibromocarbene CBr2 and acetaldehyde CH3CHO was investigated at B3LYP / 6-31G (d) level using density functional theory. The frequency response and intrinsic coordinate reaction (IRC ) And the single point energy of CCSD (T) / 6-31G (d) and CCSD (T) / 6-31G (d, p) of each species were calculated.The results showed that the insertion of CH2 and CH3CHO The main product is propionaldehyde (HP1), and the two main reaction channels of CBr2 and CH3CHO insertion reaction are in the singlet state potential surface. The singlet CBr2 can undergo insertion reaction with Cα-H bond Ⅰ (1) The reaction Ⅱ (1) with Cβ-H bond can occur.The thermodynamic and kinetic properties of the reactions Ⅰ (1) and Ⅱ (1) in the temperature range of 100 ~ 2200K were calculated by the Wigner-corrected Eyring transition state theory The optimum temperature range of reaction Ⅰ (1) and Ⅱ (1) is 10 ~ 25kPa at temperature of 250 ~ 1750 and 250 ~ 1600k, respectively. The reaction Ⅰ (1) ) Reaction rate and the equilibrium conversion rate vary greatly, with good selectivity, more conducive to the dibromocarbene inserted acetaldehyde Cα-H bond to generate the product P1 reaction Ⅰ (1) of the occurrence, and in 10 00 ~ 1600K range, the reaction has no obvious advantage of choice.