GAS-PHASE REACTION OF OZONE WITH 2-METHYL-2-BUTENE - DICARBONYL FORMATION FROM CRIEGEE BIRADICALS

Carbonyl products have been isolated and identified in the reaction of ozone with 2-methyl-2-butene in the dark under simulated atmospheric conditions. These carbonyls include acetone, acetaldehyde, methylglyoxal, and formaldehyde (major), hydroxyacetone and glyoxal (minor), and hydroxyacetaldehyde and 3-hydroxy-4-methyl-2-butanone (tentative). The product distribution is consistent with intramolecular H-atom abstraction and other rearrangement, pathways of the substituted Criegee biradicals, R1R2ĊOȮ (R1 = CH3, R2 = H and CH3). Carbonyls product analysis also indicates a substantial contribution of OH-olefin pathways in the ozone–olefin reaction in the dark and, conversely, of ozone–olefin pathways in the OH–olefin reaction (sunlight-irradiated olefin–NO mixtures). Current computer kinetic air quality models of olefin atmospheric chemistry should be updated to account for the reaction pathways of substituted Criegee biradicals. © 1990, American Chemical Society. All rights reserved.