Pressure Stabilization of Criegee Intermediates Formed from Symmetric trans-Alkene Ozonolysis.

We explore the pressure dependence of a stabilized Criegee Intermediate (sCI) formation from a sequence of trans-alkene ozonolysis reactions. To study the effect of carbon chain length on the stabilization, we select five symmetric trans-alkenes ranging from trans-2-butene (C) through trans-7-tetradecene (C). We measure the pressure falloff curves for each alkene from 50 to 900 Torr in a flow reactor using conversion of SO to HSO with and without an OH scavenger, and subsequent detection of HSO with a nitrate chemical ionization mass spectrometer to constrain sCI yields.

Pressure-Dependent Criegee Intermediate Stabilization from Alkene Ozonolysis.

We explored the pressure dependence of acetone oxide (stabilized Criegee Intermediate, sCI) formation from 2,3-dimethyl-2-butene ozonolysis between 50 and 900 Torr using a new, highly accurate technique. We exploited the ability of the sCI to oxidize SO2 to H2SO4, which we measured with a chemical ionization mass spectrometer. We produced the Criegee intermediates (CI) in a high-pressure flow reactor via ozonolysis of 2,3-dimethyl-2-butene (tetramethyl ethylene, TME) and measured the relative H2SO4 concentrations with and without an added OH scavenger.