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" From Atkinson (1994).

h Numbers in parentheses from Kramp and Paulson (1998).

" From Atkinson (1994).

h Numbers in parentheses from Kramp and Paulson (1998).

alkyl radical formed in reaction (61) adds 02 and ultimately forms benzaldehyde and smaller amounts of benzyl nitrate, as shown in Fig. 6.12.

The greatest uncertainty in the mechanism is the fate of the stabilized OH-aromatic adduct. It had been assumed that it would react with Oz and ultimately lead to the formation of oxygenated compounds. However, there is also some evidence that the kinetics of the reaction of the adduct with 02 may be sufficiently slow at room temperature that the reaction with N02 may be competitive at the relatively high concentrations of N02 used in laboratory studies of these reactions. The rate constants at room temperature for the reactions with 02 and N02 have been reported to be ~5 X 10"16 and -3x10"" cm3 molecule"1 s"1, respectively (Knispel et al., 1990; Goumri et al., 1991), in which case the removal of the adduct by these two pathways at 1 atm in air would be equal only at the very high N02 concentration of ~3.5 ppm. While these kinetic data suggest that the adduct will react with 02 under atmospheric conditions, in many labora-

CH20N02

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