Product yields of stabilized Criegee intermediates in the ozonolysis reactions of cis-2-butene, 2-methyl-2-butene, cyclopentene, and cyclohexene

Cavity ring-down spectroscopy (CRDS) was utilized in combination with chemical titration with sulfur dioxide (SO₂) to quantify stabilized Criegee intermediates (sCIs) produced at low pressures (4–20 Torr) in ozonolysis reactions of cis-2-butene, 2-methyl-2-butene, cyclopentene, and cyclohexene. The yield of stabilized sCI, acetaldehyde oxide (CH₃CHOO), from cis-2-butene ozonolysis decreased with decreasing pressure and reached to 0.05±0.04 at the zero-pressure limit. The nonsymmetric alkene 2- methyl-2-butene produced two stabilized sCIs, CH₃CHOO and acetone oxide ((CH₃)₂COO), and their total yield decreased with decreasing pressure and reached 0.01±0.03 at the zero-pressure limit. For cyclopentene and cyclohexene, the sCI yields were essentially constant near zero, as expected of endocyclic alkenes. The nascent yields of sCI of various alkenes are compared.