Hydroxyl radical reactions in the gas phase. Products and pathways for the reaction of hydroxyl with toluene

A smog chamber and modeling study of the gas phase NOx–air photooxidation of toluene and the cresols

“…Table I1 lists the experimental and calculated (using model A) yields of the major products monitored, and gives the maximum calculated yields of major products predicted by the model which were not experimentally monitored. Among the products monitored, the major discrepancy appears to be that the observed nitrotoluene yields are higher by a factor of -10 than those calculated, despite the fact that the calculations generally fit the cresol data and used the experimentally determined ratio ( k 4 2 / k 4 3 ) for cresol versus nitrotoluene formation obtained by Kenley et al [19]. In addition, the predicted formaldehyde yields are slightly low, relative to the experimental data.…”

“…This reaction proceeds via two pathways: H atom abstraction from the substituent methyl group [reaction (35)], and OH radical addition to the ring [reaction (41)] [8,9,12,15,17,19,20,28- Experimental data; (-, ---) calculated. (40)], as has been discussed previously [8,9,19,20,. The reasonably good fits of the model calculations to the experimental benzaldehyde yields (see Table 11) indicate that our data are consistent with the reported ratios [9, 15,19,20] for OH abstraction versus addition to the aromatic ring.…”

“…(40)], as has been discussed previously [8,9,19,20,. The reasonably good fits of the model calculations to the experimental benzaldehyde yields (see Table 11) indicate that our data are consistent with the reported ratios [9, 15,19,20] for OH abstraction versus addition to the aromatic ring.…”

“…The general reactions listed in Appendix B were applied to both the toluene-NO,-air and the o-cresol-NO,-air mechanisms, and are intended to be applicable to the NO,-air photooxidations of all substituted benzenes (see notes [14][15][16][17][18][19]26, and 27 of Appendix A and the discussion below). A number of possible alternative mechanisms, discussed below, were examined, and the appendices list all reactions considered, including those that were subsequently found to give unacceptable fits to the data.…”

“…In recent years laboratory studies have shown that under atmospheric conditions the major initial reaction of the aromatics is with the hydroxyl radical [9-201, and data are now available concerning both the overall OH radical rate constants [9-181 and the relative amounts of OH radical addition and H atom abstraction [9,15,16,19,20] for many of these compounds. Additionally, the reactions of ozone with the aromatic hydrocarbons, leading to the production of a-dicarbonyls [21], have been shown to be negligible under atmospheric conditions [21-241. Several product studies of irradiated NO,-aromatic-air systems (mainly of the NO,-toluene-air) have been carried out 125-341, although quantitative measurements of a large variety of products and of the reactants under carefully controlled experimental conditions have not yet been made available.…”