Carbonyl Oxide Stabilization from Trans Alkene and Terpene Ozonolysis

Abstract

The pressure dependence of carbonyl oxide (Criegee intermediate) stabilization can be measured via H 2 SO 4 detection using chemical ionization mass spectrometry. By selectively scavenging OH radicals in a flow reactor containing an alkene, O 3 , and SO 2 , we measure an H 2 SO 4 ratio related to the Criegee intermediate stabilization, and by performing experiments at multiple pressures, we constrain the pressure dependence of the stabilization. Here, we present results from a set of monoterpenes as well as isoprene, along with previously published results from tetramethylethylene and a sequence of symmetrical trans alkenes. We are able to reproduce the observations with a physically sensible set of parameters related to standard pressure falloff functions, providing both a consistent picture of the reaction dynamics and a method to describe the pressure stabilization following ozonolysis of all alkenes under a wide range of atmospheric conditions.

Collection on the Spectroscopy, Structure, and Reactivity of Stabilized Criegee Intermediates

“…This in situ production of sCIs involves UV photolysis of an organic diiodide compound in the presence of O 2 and can generate sufficient densities for spectroscopic or kinetic studies. As is noted above, very different chemistry leads to the natural formation of sCIs in the Earth’s atmosphere; the alkene ozonolysis reactions mostly responsible are now also accessible to detailed laboratory and computational investigation. − However, previously unexpected routes to sCIs involving reactions of peroxy radicals have also recently been proposed. , …”