Max Planck Institute for Chemistry, Mainz, Germany.
Phys Chem Chem Phys. 2012 Nov 14;14(42):14682-95. doi: 10.1039/c2cp42300f. Epub 2012 Oct 2.
The reaction of Criegee intermediates (CI) with NO and RO(2) radicals is studied for the first time by theoretical methodologies; additionally, the reaction of CI with SO(2) molecules is re-examined. The reaction of CI with NO was found to be slow, with a distinct energy barrier. Their reaction with RO(2) radicals proceeds by the formation of a pre-reactive complex followed by addition of the RO(2) radical on the CI carbon over a submerged barrier, leading to a larger peroxy radical and opening the possibility for oligomer formation in agreement with experiment. The impact of singlet biradicals on the reaction of CI with SO(2) is examined, finding a different reaction mechanism compared to earlier work. For larger CI, the reaction with SO(2) at atmospheric pressures mainly yields thermalized sulfur-bearing secondary ozonides. The fate of the CI in the atmosphere is examined in detail, based on observed concentration of a multitude of coreactants in the atmosphere, and estimated rate coefficients available from literature data. The impact of SCI on tropospheric chemistry is discussed.
首次通过理论方法研究了 Criegee 中间体 (CI) 与 NO 和 RO(2)自由基的反应；此外，还重新检查了 CI 与 SO(2)分子的反应。发现 CI 与 NO 的反应缓慢，存在明显的能量障碍。它们与 RO(2)自由基的反应通过形成预反应络合物进行，然后 RO(2)自由基在 CI 碳上越过淹没的势垒加成，导致更大的过氧自由基，并为寡聚物形成开辟了可能性，这与实验结果一致。 singlet biradicals 对 CI 与 SO(2)反应的影响进行了检查，与早期的工作相比，发现了不同的反应机制。对于较大的 CI，在大气压力下与 SO(2)的反应主要产生热解含硫的二次臭氧化物。根据大气中多种反应物的观测浓度以及从文献数据中估算得到的可用速率系数，详细研究了 CI 在大气中的命运。讨论了 SCI 对对流层化学的影响。
