The absolute rate constants of the addition of H and D atoms to propylene-d0 and -d6 have been measured by means of the pulse radiolysis-resonance absorption technique over the temperature range of 200–500 K. The rate constants obtained were well expressed by these Arrhenius equations: k(H+C3H6)=(3.00±0.38)exp[−(1612±66)⁄RT], k(H+C3D6)=(2.55±0.57)exp[−(1509±128)⁄RT], k(D+C3H6)=(1.99±0.05)exp[−(1550±15)⁄RT], and k(D+C3D6)=(2.20±0.27)exp[−(1587±67)⁄RT] in units of 10−11 cm3 molecule−1 s−1. The unit of activation energy is cal mol−1. Practically no isotope effects attributable to the difference between C3H6 and C3D6 could be observed. This is similar to the kinetic isotope effects previously observed in the rate constants of the addition of H and D atoms to isotopic ethylenes. The theoretical rate constants of the above reactions have been calculated by the conventional activated complex theory using the potential energy surface drawn by the ab initio method; however, no agreement with regard to the isotope effects could be obtained between experiment and theory because of the difference between C3H6 and C3D6. This also is similar to the isotope effects found in the H+C2H4→C2H5 reaction.
通过脉冲辐射解离-共振吸收技术,在200–500 K的温度范围内测定了H和D原子与
丙烯-d0和-d6的加成反应的绝对速率常数。所得的速率常数可以用以下阿伦尼乌斯方程很好地表示:k(H+
C3H6)=(3.00±0.38)exp[−(1612±66)⁄RT],k(H+C3D6)=(2.55±0.57)exp[−(1509±128)⁄RT],k(D+ )=(1.99±0.05)exp[−(1550±15)⁄RT],和k(D+C3D6)=(2.20±0.27)exp[−(1587±67)⁄RT],单位为10−11 cm3 molecule−1 s−1。活化能的单位是cal mol−1。几乎没有可归因于 和C3D6之间差异的同位素效应被观察到。这与之前在H和D原子与同位素
乙烯加成速率常数中观察到的动能同位素效应相似。上述反应的理论速率常数是通过常规的活化复合物理论,使用从头算方法绘制的势能面计算的;然而,由于 和C3D6之间的差异,实验和理论之间无法就同位素效应达成一致。这也与H+
C2H4→
C2H5反应中发现的同位素效应相似。