Carnegie Mellon, University, Pittsburgh, Pennsylvania, USA.
J Phys Chem A. 2011 Jan 20;115(2):161-6. doi: 10.1021/jp108773d. Epub 2010 Dec 16.
We present measurements of the pressure dependence of stabilized Criegee intermediate (SCI) formation utilizing a hexafluoroacetone scavenger. SCI yields in the ozonolysis of 2,3-dimethyl-2-butene (TME) were measured in a high pressure flow reactor within a range of 50-710 Torr. Within this pressure range, SCI yields increase linearly with pressure. A zero pressure intercept of about 15% indicates that a significant fraction of CI are formed below the barrier to isomerization. By comparison of our results of the pressure dependence of SCI formation and both prompt and long-time OH yields, our results indicate that OH formation from ozonolysis proceeds via at least two intermediates, the SCI and presumably a vinylhydroperoxide (VHP).
我们利用六氟丙酮清除剂对稳定的 Criegee 中间体 (SCI) 形成的压力依赖性进行了测量。在 50-710 托的范围内，在高压流动反应器中测量了臭氧分解 2,3-二甲基-2-丁烯 (TME) 时的 SCI 产率。在这个压力范围内，SCI 产率随压力线性增加。零压力截距约为 15%，表明相当一部分 CI 是在异构化势垒以下形成的。通过比较 SCI 形成的压力依赖性以及瞬态和长时间 OH 产率的结果，我们的结果表明，臭氧分解生成 OH 的过程至少涉及两种中间体，即 SCI 和可能的乙烯基过氧化物 (VHP)。
