Institute of Atomic and Molecular Sciences, Academia Sinica, PO-Box 23-166, Taipei, 10617, Taiwan.
Phys Chem Chem Phys. 2018 Aug 1;20(30):20217-20227. doi: 10.1039/c8cp02064g.
Criegee intermediates (CIs), formed in the reactions of unsaturated hydrocarbons with ozone, are very reactive carbonyl oxides and have recently been suggested as important oxidants in the atmosphere. In this work, we studied the substituent effect on the water monomer and dimer reaction with CIs which include up to three carbon atoms at the QCISD(T)/CBS//B3LYP/6-311+G(2d,2p) level. Our calculation showed that for saturated CIs with a hydrogen atom on the same side as the terminal oxygen atom, the reaction with water vapor would likely dominate the removal processes of these CIs in the atmosphere. On the other hand, for unsaturated CIs, the reactivity toward water vapor decreases compared to the saturated species allowing them to survive in humid atmospheric environments. We also evaluated the kinetic isotope effect in the reaction between CI and water vapor by performing calculations with deuterated water. We found that tunneling is not important and the kinetic isotope effect mainly comes from the difference in the zero point energy between water and deuterated water.
Criegee 中间体（CIs）是在不饱和烃与臭氧反应中形成的非常活泼的羰基氧化物，最近被认为是大气中重要的氧化剂。在这项工作中，我们研究了取代基对包括最多三个碳原子的 CIs 与水单体和二聚体反应的影响，这是在 QCISD(T)/CBS//B3LYP/6-311+G(2d,2p)水平上进行的。我们的计算表明，对于在同一侧末端氧原子上有氢原子的饱和 CIs，与水蒸气的反应可能主导这些 CIs 在大气中的去除过程。另一方面，对于不饱和 CIs，与水蒸气的反应活性与饱和物种相比降低，从而使它们能够在潮湿的大气环境中存活。我们还通过用重水进行计算评估了 CI 与水蒸气之间反应的动力学同位素效应。我们发现隧道效应不重要，动力学同位素效应主要来自于水和重水之间零点能的差异。
