Nitrate radical cresol reactions

Cresols degrade rapidly in air. Removal during the day is dominated by the reaction with hydroxyl radical (HO-), while nighttime removal is probably dominated by the nitrate radical. Reaction with other oxidants in air (e.g., ozone) will be much slower than reactions with hydroxyl or nitrate radical (Atkinson and Carter 1984). 

Carter, W.P.L., Winer, A.M., Pitts, Jr., J.N. (1981) Major atmospheric sink for phenol and the cresols. Reaction with the nitrate radical. Environ. Sci. Technol. 15, 829-831. 

Chemical/Physical. Products identified from the reaction of toluene with nitric oxide and OH radicals include benzaldehyde, benzyl alcohol, 3-nitrotoluene, p-methylbenzoquinone, and o, m, and p-cresol (Kenley et ah, 1978). Gaseous toluene reacted with nitrate radicals in purified air forming the following products benzaldehyde, benzyl alcohol, benzyl nitrate, and 2-, 3-, and 4-nitro-toluene (Chiodini et al., 1993). Under atmospheric conditions, the gas-phase reaction with OH radicals and nitrogen oxides resulted in the formation of benzaldehyde, benzyl nitrate, 3-nitrotoluene, and o-, m-, and p-cresol (Finlayson-Pitts and Pitts, 1986 Atkinson, 1990). 

In addition to degradation by hydroxyl and nitrate radicals, all three cresol molecules absorb small amounts of W light with wavelengths above 290 nm (Sadtler Index 1960a, 1960b, 1966). Therefore, direct photolysis is also possible however, the photolysis rate is probably slow compared to the reaction with atmospheric radicals. 

As seen in Table 6.1, the reactions of the nitrate radical with the simple aromatic hydrocarbons are generally too slow to be important in the tropospheric decay of the organic. However, one of the products of the aromatic reactions, the cresols, reacts quite rapidly with NO,. o-Cresol, for example, reacts with N03 with a room temperature rate constant of 1.4 X 10 " cm3 molecule-1 s-1, giving a lifetime for the cresol of only 1 min at 50 ppt N03. This rapid reaction is effectively an overall hydrogen abstraction from the pheno-... 

Nitrated hydroxyaromatics may enter into the atmosphere from both primary and secondary sources. The formation of nitrophenols and nitrocresols in die combustion processes of motor vehicles has been reported by Tremp et al. (1993). Others primary sources may be combustion of coal, wood, manufacture of phenol-formaldehyde resins, pharmaceuticals disinfectants, dyes and explosives (Harrison et al., 2005). Studies in our and other laboratories have shown that an additional important source of diese compounds in the atmosphere could be the gas-phase OH-radical initiated photooxidation of aromatic hydrocarbons such as benzene, toluene, phenol, cresols and dihydroxybenzenes in the presence of NOx during the daytime as well as the reaction of NO3 radicals widi these aromatics during the night time (Atkinson et al., 1992 Olariu et al., 2002). Once released or... 

Reaction rates in the presence of oxygen and nitric oxides [82], in the presence of hydroxyl radicals [89] or in the presence of mixtures of nitric oxides of varying composition [90] have been compared for various aromatics, m-xylene and trimethyl benzenes react substantially faster than the other xylenes, toluene, and in particular benzene. In the presence of nitric oxides, the following products are formed from aromatics with side chains particularly from toluene methyl glyoxal, dimethyl glyoxal, and biacetyl [83,84], larger quantities of m-nitrotoluene, 2-methyl-4-nitro-phenol, 2-methyl-4,6-dinitrophenol, benzaldehyde, benzyl nitrate, o-cresol, and p-nitrophenol [91-93]. 

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