REACTIONS OF ALKENES INCLUDING BIOGENICS

FIGURE 6.1 Possible fates of the 2-hexoxy and 3-hexoxy free radicals (adapted from Eberhard et al 1995). 

It should be noted that some alkoxy radicals derived from oxygenated compounds may have some unique chemistry in addition to these reactions. For example, Tuazon et al. (1998b) have shown that alkoxy radicals derived from OH + acetate reactions, i.e., R C(0)0CH(0 )R2 rearrange and decompose to RCO and the acid RC(0)0H. 

In summary, alkyl radicals, R, are all converted to alkylperoxy radicals, R02, in the troposphere. R02 reacts with NO, except in very remote regions where the concentration of NO is of the order of 40 ppt or less. The reaction converts NO to N02 and hence acts as a source of O-, via the N02 photolysis. For the larger alkylperoxy radicals, a substantial portion of the R02 + NO reaction also gives the stable alkyl nitrate, 

As discussed in more detail in Section J.2.b, in remote regions where the NO concentrations are very low, reactions of R02 with other peroxy radicals such 

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The reaction of ozone with alkenes produces OH and other radicals. Work in LACTOZ has provided quantitative data for the yield of OH for a variety of alkenes, including biogenic hydrocarbons. Yields of around 50 % were obtained for the reaction of ozone with typical alkenes, making this a source of atmospheric free radicals, which is especially significant at night-time when photolytic sources are absent. 

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