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采用B3LYP、QCISD、MP2方法在6-311+G(d)基组水平上对叠氮酸与氨氰环加成反应进行了详细研究。首先对所有的反应物、过渡态和产物的构型进行了全参数优化,并用频率分析和内禀反应坐标(IRC)方法对过渡态进行确认。以步长为0.1(amu)1/2 bohr的内禀反应坐标方法在B3LYP/6-311+G(d)方法和基组水平上计算了内禀反应坐标s为(-3.00～3.00)(amu)1/2 bohr范围内反应的键长、振动频率、NBO电荷变化情况。根据统计热力学方法和用Wigner校正的Eyring过渡态理论,计算了(200～450)K温度范围内反应热力学函数及速率常数,探讨了温度对反应的影响。结果表明,反应经过过渡态TS生成5-AT的活化能为117.14 kJ/mol(B3LYP)、130.18 kJ/mol(QCISD)和106.24 kJ/mol(MP2),产物的相对能量为-74.24 kJ/mol(B3LYP)、-87.01 kJ/mol(QCISD)和-79.09 kJ/mol(MP2);反应随温度的升高更具有动力学优势,但在热力学上低温下更易于进行,因此,结合热力学和动力学因素,我们认为(300～350)K是该反应的适宜温度。
Addition reaction of azido acid with cyanamide ring has been studied in detail at B3LYP, QCISD and MP2 levels at 6-311 + G (d) basis level. All the reactants, transition states and product configurations were optimized for all parameters. The transition states were confirmed by the frequency analysis and the intrinsic reaction coordinate (IRC) method. The intrinsic reaction coordinate s (-3.00 ~ 3.00) was calculated from the B3LYP / 6-311 + G (d) method and the basis set at the intrinsic reaction coordinate of 0.1 amu 1/2 bohr amu) 1/2 bohr reaction length of the bond, vibration frequency, NBO charge changes. According to the statistical thermodynamic method and the Eyring transition state theory calibrated by Wigner, the reaction thermodynamic functions and rate constants in the temperature range of (200-450) K were calculated and the effect of temperature on the reaction was discussed. The results showed that the activation energies of 5-AT through the transition state TS were 117.14 kJ / mol (B3LYP), 130.18 kJ / mol (QCISD) and 106.24 kJ / mol (MP2) respectively. The relative energy of the product was -74.24 kJ / mol (B3LYP), -87.01 kJ / mol (QCISD) and -79.09 kJ / mol (MP2) respectively. The reaction is more kinetic with increasing temperature, but it is easier to carry out at lower temperatures in thermodynamics. Therefore, We know (300 ~ 350) K is the appropriate temperature for the reaction.