论文部分内容阅读
用二阶微扰和密度泛函理论研究了单重态二甲基亚烷基卡宾与丙酮的环加成反应机理,采用MP2/6-31G*和B3LYP/6-31G*方法计算了势能面上各驻点的构型参数、振动频率和能量.结果表明,反应(1)的b途径是单重态二甲基亚烷基卡宾与丙酮环加成反应的主反应通道.该反应途径由两步组成:(ⅰ)两反应物首先生成了一富能的中间体INT1b,它是一无势垒的放热反应,放出的热量为23.3kJ/mol,(ⅱ)中间体INT1b通过过渡态TS1b异构化为三元环产物P1,其势垒为22.2kJ/mol.该反应途径与其竞争反应的反应速率相差较大,具有很好的选择性.从热力学和动力学的角度综合分析,该反应在1大气压(101325Pa)下,温度为300~800K时进行为宜,如此,反应既有较大的自发趋势和平衡常数,又具有较快的反应速率.
The second order perturbation and density functional theory have been used to study the cycloaddition reaction mechanism of monomethyldi (alkylene) carbene with acetone. The potential energy surface is calculated using MP2 / 6-31G * and B3LYP / 6-31G * methods. The results show that the b pathway of reaction (1) is the main reaction channel of the addition reaction of monometallulydimethylenealkylenecarbin and acetone. The reaction pathway consists of The two-step composition: (i) The two reactants first generate an energy-rich intermediate, INT1b, which is an exothermic reaction without a barrier and releases 23.3 kJ / mol of heat, (ii) the intermediate INT1b passes through the transition state The isomerization of TS1b into a three-membered ring product P1 with a potential barrier of 22.2 kJ / mol shows a good selectivity for its reaction rate with its competitive reaction.From the perspective of thermodynamics and kinetics, The reaction at 1 atmosphere (101325Pa) at a temperature of 300 ~ 800K when appropriate, so that the reaction has both a larger spontaneous tendency and equilibrium constant, but also has a faster reaction rate.