Oxidation isoprene product distribution

Product distributions resulting from the OH radical induced oxidation of the following hydrocarbons have been determined 2-methyl-propane, 2,3-dimethyl-butane, 2-methyl-butane, n-pentane, cyclohexane, methySubstituted 1-butenes, isoprene, toluene. Whenever possible, branching ratios for the self-reactions of alkylperoxy radicals and decomposition rate coefficients for alkoxyl radicals were derived. 

Of the atmospheric chemistry of the biogenic hydrocarbons, by far the most is known about isoprene. Whereas rate constants of many other biogenic hydrocarbons with OH, O3, and NO, have been measured, comparatively little is known about the distribution of products. Hatakeyama et al. (1989, 1991) and Arey et al. (1990) have measured some of the products of the a-pinene-O, reaction, including pinonaldehyde, norpinonaldehyde, formaldehyde, CO, and COj. Considerable work remains to be done in elucidating the atmospheric oxidation mechanisms of biogenic hydrocarbons. 

Ketones are emitted directly to the atmosphere, and their sources were discussed in detail in chapter I. In the U.K. acetone and butanone comprise about 1% and 5%, respectively, of the total anthropogenic emissions of oxygenated compounds, and 1.6% and 1.1%, respectively, of the total anthropogenic emissions of nonmethane volatile organic compounds. Ketone emissions from solvents (both industrial and personal) are substantial emissions from both gasoline- and diesel-fueled vehicles also contribute. Ketones are also formed extensively in the atmosphere in the oxidation of other compounds. Acetone, for example is formed in the OH-initiated oxidation of propane, iio-butane, iso-pentane, and neopentane and from a number of higher hydrocarbons. It is also formed in the oxidation of terpenes. The distribution, sources, and sinks of acetone in the atmosphere have been analyzed by Simpson et al. (1994). Methyl vinyl ketone is an important first generation product in the OH-initiated oxidation of isoprene. 

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