Environment Research Institute, Shandong University, Binhai Road 72, Jinan 266237, China.
Molecules. 2018 Sep 3;23(9):2240. doi: 10.3390/molecules23092240.
Mechanism and kinetic studies have been carried out to investigate whether one and two water molecules could play a possible catalytic role on the CH₂O + ClO reaction. Density functional theory combined with the coupled cluster theory were employed to explore the potential energy surface and the thermodynamics of this radical-molecule reaction. The reaction proceeded through four different paths without water and eleven paths with water, producing H + HCO(O)Cl, Cl + HC(O)OH, HCOO + HCl, and HCO + HOCl. Results indicate that the formation of HCO + HOCl is predominant both in the water-free and water-involved cases. In the absence of water, all the reaction paths proceed through the formation of a transition state, while for some reactions in the presence of water, the products were directly formed via barrierless hydrogen transfer. The rate constant for the formation of HCO + HOCl without water is 2.6 × 10 cm³ molecule s at 298.15 K. This rate constant is decreased by 9-12 orders of magnitude in the presence of water. The current calculations hence demonstrate that the CH₂O + ClO reaction is impeded by water.
已经进行了机理和动力学研究，以探讨一个和两个水分子是否可以在 CH₂O + ClO 反应中发挥可能的催化作用。采用密度泛函理论结合耦合簇理论来探索这个自由基-分子反应的势能面和热力学。在没有水的情况下，反应经过四条不同的路径，而在有水的情况下，反应经过十一条路径，生成 H + HCO(O)Cl、Cl + HC(O)OH、HCOO + HCl 和 HCO + HOCl。结果表明，在无水和含水两种情况下，HCO + HOCl 的生成都是主要的。在无水的情况下，所有反应路径都通过过渡态进行，而在一些有水的反应中，产物则通过无势垒的氢转移直接生成。在 298.15 K 时，无水条件下 HCO + HOCl 生成的速率常数为 2.6 × 10 cm³ molecule s。在有水的情况下，这个速率常数降低了 9-12 个数量级。因此，目前的计算表明，CH₂O + ClO 反应受到水的阻碍。
