Nitrate radical alkenes, 243, Table

TABLE 6.21 Rate Constants for the Reaction of Hydroxyl and Nitrate Radicals and Ozone with Alkenes... 

Nitrate radicals (NO3) are formed by the reaction of O3 and NO2 (Sect. 5.4.2) and play an important role in atmospheric chemistry at nighttime in polluted air. NO3 has an absorption spectrum in the visible region as seen in Sect. (4.2.4) so that daytime concentration is very low since it is easily photodecomposed by sun light. Simultaneously, since the reaction rate constant of NO3 with NO is large, it returns easily to NO2 by NO so that its concentration near NO sources is also very low. NO3 reacts with alkenes and aldehydes to form dinitrates and OH/HO2 radicals at nighttime. Rate constants of fundamental reactions of atmospheric NO3 and related N2O5 are cited in Table 5.6. 

In addition to being oxidized by the hydroxyl radical, alkenes may react with the N03 radical as has been described by several investigators (52, 56, 66). Listed in Table I are some of the organic nitrates that have been predicted to be produced via reaction of OH and N03 with isoprene and pro-pene. Analogous compounds would be expected from other simple alkenes and from terpenes such as a- and (3-pinene. Other possible organic nitrates may be produced via the oxidation of aromatic compounds (53, 54) and the oxidation of carbonaceous aerosols (67). Quantitative determination of these species has not been made in the ambient atmosphere. 

The oxidation of 1-methoxycyclopropanol with iron(IIl) nitrate in methanol in the presence of but-3-en-2-one gives the 6-oxo ester in 30% yield.The mechanism may involve addition of a 2-(methoxycarbonyl)ethyl radical, obtained via iron(III) induced oxidation, to but-3-en-2-one resulting in an a-keto radical. A more effective and practical intermolecular addition of cyclopropanols to alkenes was recently performed in the presence of manganese(III) pyridine-2-carboxylate (Table 4)T 32 -phe reaction may proceed by way of (i) generation of 8-acylalkyl... 

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