INVESTIGATION OF ELEMENTARY REACTION PATHS BY EXPERIMENTS AND THEORETICAL CALCULATIONS

1. 我们测定了几种物质在高温下的初阶反应速率常数。在大多数情况下，速率常数与理论计算值符合得很好。然而，在丙醛的情况下，与计算结果相比，实验分解率很高。从计算得到的过渡态结构来看，实验速率常数高的原因是在鞍点处存在激发态，其状态数比平衡值高。结果表明，在连续反应中，二级反应是由第一过渡态的结构和能量决定的。这是化学活化的方法之一。通过这种方法的活化产生一种依赖于母体分子的特殊分子结构。实际上，酯热解生成的羧酸通过竞争路径分解，其分支比与热平衡酸的值不相同。用从头计算很好地解释了这些现象。在研究过程中，证实了基于分子轨道法的理论计算与实验结果吻合较好。这一事实被认为有助于化学动力学领域，即使现在许多实验学家也不相信理论计算的结果。

1. We determined the rate constants of elementary steps of several species at high temperatures. In most cases, the rate constants were in good agreement with the theoretically calculated values. In the case of propynal, however, the experimental decomposition rate was found very high in comparison with the calculation. From the calculated transition-state structure, the high experimental rate constant was explained by the fact that at the saddle point there are excited vibrational modes which give a higher number of state than the equilibrium value.2. It was found that in the consecutive reaction the secondary step was governed by the structure and the energy of the first transition state. This is one of the methods of chemical activation. The activation by this method gives rise to a special molecular structure depending on the parent molecule. In fact, the carboxylic acids produced from the pyrolysis of esters decomposed via competing paths whose branching ratio was not the same as the values of the thermally equilibrated acids. These phenomena were well explained by ab initio calculations.3. In the cause of this investigation it was confirmed that the theoretical calculation based on the molecular orbital method well corresponded to the experimental results. This fact is thought to contribute to the field of the chemical kinetics where even now many experimentalists do not believe, the results of the theoretical calculation.