1-Nitropyrene nitration

Nitropyrene was the sole product formed from the gas-phase reaction of pyrene with OH radicals in a NOx atmosphere (Arey et al, 1986). Pyrene adsorbed on glass fiber filters reacted rapidly with N2O5 to form 1-nitropyrene. When pyrene was exposed to nitrogen dioxide, no reaction occurred. However, in the presence of nitric acid, nitrated compounds were produced (Yokley et al, 1985). Ozonation of water containing pyrene (10-200 pg/L) yielded short-chain aliphatic compounds as the major products (Corless et al, 1990). A monochlorinated pyrene was the major product formed during the chlorination of pyrene in aqueous solutions. At pH 4, the reported half-lives at chlorine concentrations of 0.6 and 10 mg/L were 8.8 and <0.2 h, respectively (Mori et al, 1991). 

The generality of this reaction of N02 with particle-associated PAHs was demonstrated when, under similar laboratory conditions, perylene (a weak promutagen) was converted to 3-nitroperylene, and pyrene (a nonmutagen), at a slower rate, to 1-nitropyrene both nitro-PAHs are direct-acting frameshift mutagens. In a similar experiment, chrysene was not nitrated this is consistent with its low reactivity in the Nielsen reactivity scale (Table 10.30). 

In the mid-1980s, the discovery of significant amounts of 2-nitropyrene in ambient particulate matter collected in a rural region of Denmark by Nielsen and co-workers (1984) and 2-nitrofluoranthene in southern California by Pitts and colleagues (1985b) provided unique initial evidence for the possible formation of nitroarenes by reactions of precursor PAHs in ambient air. Thus, these compounds are not electrophilic nitration products of their parent PAHs and are generally not observed in combustion sources such as diesel soot see, for example, Table 10.34 and the report of Ciccioli and co-workers on the detection of emissions of 2-nitrofluoranthene and 2-nitropyrene solely from a very minor Italian industrial source (see Ciccioli et al., 1993, 1995, 1996, and references therein). 

Yamazaki H et al., Bioactivation of diesel exhaust particle extracts and their major nitrated polycychc aromatic hydrocarbon components, 1 -nitropyrene and dinitropyrenes, by human cytochromes P450 1 Al, 1A2, and 1B1, Mutat. Res., 472, 129, 2000. 

Detection of nitrated PAHs (NPAHs) is possible using ECD and can be made more sensitive by preparing the fluorinated derivatives of NPAHs with heptafluorobutyric anhydride (HFBA). The fine fraction (<0.5 /rm) of urban air particulate matter in Saitama, Japan contained about ten times the amount of NPAHs as the course fraction with levels as high as 111 pg m for 1-nitropyrene and 18 pg m for 1-nitronaphthalene. 

Headspace Effects and Stoichiometry. In the earlier accounts of pyrene nitration by N(IV), NO was a prominent reaction product, and each N204 ultimately yeilded IV3 nitropyrenes (7, 9). Our work found substantial effects of NO on reaction rate, as just discussed, and also effects of headspace on nitropyrene yields, as estimated spectrophotometrically. Specifically, we found in the runs with [Py] [N(IV)] that with a large headspace the 1-nitropyrene/N204 ratio ranged from 0.9 to 1.3 however, with a small head-space, this ratio approached and in some cases exceeded 2.0. 

Accordingly, a study of the stoichiometry of pyrene nitration by N(IV) in methylene chloride was conducted by using gas chromatography for analysis. The results are summarized as follows Starting with 79.1 (xmol of pyrene and 7.6 xmol of N(IV) led to a mass balance of 97.5% and a 1-nitropyrene/ N204 ratio of 2.4 starting with 109.8 xmol of pyrene and 15.1 (xmol of N(IV) led to a mass balance of 94.3% and a 1-nitropyrene/N204 ratio of 1.8. 

Combustion emissions from both motor vehicles and stationary sources contain a complex mixture of organic compounds. Chemical characterization of these organics shows that they contain carcinogenic polycyclic aromatic hydrocarbons (PAH), such as benzo(a)pyrene. Recently, chemical characterization studies of motor-vehicle emissions have identified the presence of methylated PAHs (e.g., methylphenanthrenes) (1), nitrated PAHs (e.g., nitropyrene) (2), oxidized PAHs (e.g., 4 oxapyrene-5-one)... 

The highest nitration rates are observed for pyrene, which in the presence of 8 is quantitatively transformed into 1-nitropyrene within 9 min in a dinitrogen atmosphere ([ArH]o=0.092 M. a NaN02 ArH molar ratio is 4 1). When the catalyst is absent, no nitration occurs for at least 4 h. The ability of 8 and 9 to transfer protons from an aqueous phase to benzene was also reported. 

Nitrated polycyclic aromatic hydrocarbons, such as 1-nitropyrene, 1-nitrosopyr-ene and 1,3-dinitropyrene, have been measured in car exhaust deposits by HPLC with chemiluminescence detection after on-line EC reduction (PGEs, —1.6 V vs Pd)." LoDs of fmol on-column were claimed. 

Uncombusted PAH from diesel fuels can react with oxides of nitrogen in the exhaust to form nitrated PAH. Some of them, for example, 1-nitropyrene and dinitropyrenes, have been shown to be potent mutagens in Ames assays [64]. Due to this environmental health concern, nitrated PAHs have been studied by various GG and MS techniques [66,67], Oxygenated PAHs found in diesel particulates include polycyclic ketones and quinones, carboxaldehydes, and hydroxy-PAH [68],... 

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