Oxygen-containing compounds hydroxyl radical reaction

TABLE 6.26 Rate Constants for the Reaction of Hydroxyl Radicals with Oxygen-Containing Compounds at Ambient Temperatures"... 

A free radical is an atom, molecule, or compound that contains one or more unpaired electrons. Common radicals include the hydrogen atom and most transition metal ions, as well as oxygen, which is a biradical since its outer two electrons have parallel spins and, therefore, are unpaired. The first reported free radical reaction was presumably by Fenton (F7), although free radicals were not known to exist at the time. The classic mechanism (Fenton reaction) with ferrous iron (as well as various other transition metal ions) predicts that hydrogen peroxide is reduced at the iron center with generation of the hydroxyl free radical (FIO). 

In this schematic reaction equation, R is the fraction of an organic compound, which contains no heteroatom and needs one atom of oxygen to be transformed to fully oxidized elements. (Actual values of m and n depend on the elemental composition of R to be oxidized.) This reaction competes with the side reaction of hydroxyl radical discharge (direct or indirect through formation of H202 as intermediate) to 02 (Eq. 82) without any... 

Reactions of hydroxyl radicals with polyfimctional group oxygen-containing organic compounds,... 

As exemplified by the stmctural formulas of a-pinene, P-pinene, A -carene, isoprene, and limonene, shown in Figure 16.1, terpenes contain alkenyl (olefinic) bonds, in some cases two or more per molecule. Because of these and other structural features, terpenes are among the most reactive compounds in the atmosphere. The reaction of terpenes with hydroxyl radical is very rapid, and terpenes also react with other oxidizing agents in the atmosphere, particularly ozone, O3. Turpentine, a mixture of terpenes, has been widely used in paint because it reacts with atmospheric oxygen to form a peroxide, then a hard resin. It is likely that compounds such as a-pinene and isoprene undergo similar reactions in the atmos-... 

Kerr, J.A., and D.W. Stocker (1986a), Kinetics of the reactions of hydroxyl radicals with alkyl nitrates and with some oxygen-containing organic compounds studied under simulated atmospheric conditions, J. Atmos. Chem., 4, 253—262. 

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