Sumiya Yosuke, Nagahata Yutaka, Komatsuzaki Tamiki, Taketsugu Tetsuya, Maeda Satoshi
Graduate School of Chemical Sciences and Engineering, Hokkaido University , Kita 13, Nishi 8, Kita-ku, Sapporo 060-8628, Japan.
Graduate School of Life Science, Hokkaido University , Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan.
J Phys Chem A. 2015 Dec 3;119(48):11641-9. doi: 10.1021/acs.jpca.5b09447. Epub 2015 Nov 23.
The significance of kinetic analysis as a tool for understanding the reactivity and selectivity of organic reactions has recently been recognized. However, conventional simulation approaches that solve rate equations numerically are not amenable to multistep reaction profiles consisting of fast and slow elementary steps. Herein, we present an efficient and robust approach for evaluating the overall rate constants of multistep reactions via the recursive contraction of the rate equations to give the overall rate constants for the products and byproducts. This new method was applied to the Claisen rearrangement of allyl vinyl ether, as well as a substituted allyl vinyl ether. Notably, the profiles of these reactions contained 23 and 84 local minima, and 66 and 278 transition states, respectively. The overall rate constant for the Claisen rearrangement of allyl vinyl ether was consistent with the experimental value. The selectivity of the Claisen rearrangement reaction has also been assessed using a substituted allyl vinyl ether. The results of this study showed that the conformational entropy in these flexible chain molecules had a substantial impact on the overall rate constants. This new method could therefore be used to estimate the overall rate constants of various other organic reactions involving flexible molecules.
动力学分析作为理解有机反应的反应活性和选择性的工具，其重要性最近已得到认可。然而，通过数值求解速率方程的传统模拟方法并不适用于由快速和慢速基元步骤组成的多步反应历程。在此，我们提出了一种有效且稳健的方法，通过将速率方程进行递归收缩以给出产物和副产物的总速率常数，来评估多步反应的总速率常数。这种新方法被应用于烯丙基乙烯基醚以及一种取代烯丙基乙烯基醚的克莱森重排反应。值得注意的是，这些反应的历程分别包含23个和84个局部极小值，以及66个和278个过渡态。烯丙基乙烯基醚克莱森重排反应的总速率常数与实验值一致。还使用一种取代烯丙基乙烯基醚评估了克莱森重排反应的选择性。这项研究的结果表明，这些柔性链分子中的构象熵对总速率常数有重大影响。因此，这种新方法可用于估计涉及柔性分子的各种其他有机反应的总速率常数。
