Atmospheric Photochemical Oxidation of 1-Octene: OH, O_3, and O(^3P) Reactions

Abstract

The photooxidation chemistry of 1-octene is examined in detail. Formation of OH from the O_3 reaction was examined with the use of methylcyclohexane as an OH radical tracer. The O_3,-1-octene reaction is found to produce, apparently directly, significant quantities of OH, 0.45 ± 0.2 on a per molecule of reacted 1-octene basis. Almost 100% of the reacted 1-octene could be accounted for as 80 ± 10% heptanal, 10 ± 6% thermally stabilized Criegee biradical, and ~ 1 % hexane. The OH-1-octene reaction was found to produce only 15 ± 5% heptanal. The remainder is assumed to result in the formation of alkyl nitrates, and possibly multisubstituted products. A separate experiment examining the O(^3P)-1-octene reaction showed that the sum of hexyloxirane and octanal accounted for ~75% of the reacted 1-octene. A photochemical model was developed for 1-octene oxidation and compared favorably with smog chamber results from NO-NO_2-1-octene experiments, predicting ozone maxima within ±25%.