Peroxyacyl nitrates

Sample until color appears probably 10 ml of air 94-99 Reacts with absorbing solution Ozone in fivefold excess peroxyacyl nitrate... 

The pollutants most strongly damaging to human, animal, and sometimes plant health include ozone, fine particulate matter, lead, nitrogen oxides (NO ), sulfur oxides (SOJ, and carbon monoxide. Many other chemicals found in polluted air can cause lesser health impacts (such as eye irritation). VOC compounds comprise the bulk of such chemicals. Formaldehyde is one commonly mentioned pollutant of this sort, as is PAN (peroxyacyl nitrate). Such... 

Photochemical air pollution consists of a complex mixture of gaseous pollutants and aerosols, some of which are photochemically produced. Among the gaseous compounds are the oxidizing species ozone, nitrogen dioxide, and peroxyacyl nitrate ... 

Primary pollutants are those emitted directly to the atmosphere while secondary pollutants are those formed by chemical or photochemical reactions of primary pollutants after they have been admitted to the atmosphere and exposed to sunlight. Unbumed hydrocarbons, NO, particulates, and the oxides of sulfur are examples of primary pollutants. The particulates may be lead oxide from the oxidation of tetraethyllead in automobiles, fly ash, and various types of carbon formation. Peroxyacyl nitrate and ozone are examples of secondary pollutants. 

Mudd, J. B., and W. M. Dugger, Jr. The oxidation of reduced pyridine nucleotides by peroxyacyl nitrates. Arch. Biochem. Biophys. 102 52-58, 1%3. 

Taylor, O. C., and D. C. MacLean. Nitrogen oxides and the peroxyacyl nitrates, pp. E1-E14. In J. S. Jacobson, and A. C. Hill, Eds. Recognition of Air Pollution Injury to Vegetation A Pictoiial Atlas. Pittsburgh Air Pdlutkm Control Association, 1970. 

Photolytic. Major products reported from the photooxidation of butane with nitrogen oxides under atmospheric conditions were acetaldehyde, formaldehyde, and 2-butanone. Minor products included peroxyacyl nitrates and methyl, ethyl and propyl nitrates, carbon monoxide, and carbon dioxide. Biacetyl, tert-butyl nitrate, ethanol, and acetone were reported as trace products (Altshuller, 1983 Bufalini et al, 1971). The amount of sec-butyl nitrate formed was about twice that of n-butyl nitrate. 2-Butanone was the major photooxidation product with a yield of 37% (Evmorfopoulos and Glavas, 1998). Irradiation of butane in the presence of chlorine yielded carbon monoxide, carbon dioxide, hydroperoxides, peroxyacid, and other carbonyl compounds (Hanst and Gay, 1983). Nitrous acid vapor and butane in a smog chamber were irradiated with UV light. Major oxidation products identified included 2-butanone, acetaldehyde, and butanal. Minor products included peroxyacetyl nitrate, methyl nitrate, and unidentified compounds (Cox et al., 1981). 

Photolytic. Major products reported from the photooxidation of 2,3-dimethylbutane with nitrogen oxides are carbon monoxide and acetone. Minor products included formaldehyde, acetaldehyde and peroxyacyl nitrates (Altshuller, 1983). Synthetic air containing gaseous nitrous acid and exposed to artificial sunlight (A. = 300-450 nm) photooxidized 2,3-dimethylbutane into acetone, hexyl nitrate, peroxyacetal nitrate, and a nitro aromatic compound tentatively identified as a propyl nitrate (Cox et al., 1980). 

Peroxyacyl nitrates, see Acetaldehyde, Butane, 2-Bntanone, 2,3-Dimethylbntane Peroxybenzoic acid, see Toluene Peroxynitric acid, see Formaldehyde Peroxypropionyl nitrate, see 2-Methylpentane, Pentane Phenanthrene, see Anthracene, Bis(2-ethylhexyl) phthalate, Naphthalene Phenanthrene-9,10-dione, see Phenanthrene 9,10-Phenanthrenequinone, see Phenanthrene 4-Phenanthroic acid, see Pyrene... 

Grosjean, E., Grosjean, D., and Seinfeld, J.H. Atmospheric chemistry of 1-octene, 1-decene, and cyclohexane gas-phase carbonyl and peroxyacyl nitrate products. Environ. ScL Technol, 30(3) 1038-1047, 1996. 

One of the most important of these reactions occurs between a peroxyl radical and nitrogen dioxide to produce compounds known as peroxyalkyl and peroxyacyl nitrates ... 

PAN is the simplest member of a series of compounds known as peroxyacyl nitrates, having the structure... 

The nomenclature for this homologous series is somewhat confused. The term PANs has been used historically to denote peroxyacyl nitrates, and this terminology continues to be used extensively in the literature, despite the lack of adherence to traditional IUPAC rules of nomenclature. Because the PANs can be considered to be mixed anhydrides of carboxylic acids and nitric acid, another suggestion (Roberts, 1990) has been peroxyacetic nitric anhydride for CH,C(0)00NO2 and peroxy carboxylic nitric anhydrides for the whole class of compounds. Although it does not follow the IUPAC rules, it would be consistent with the widespread use of the name PAN but also reflect the structure more accurately. Table 6.20 shows the structures and commonly used names of some PANs that have been observed in the atmosphere and/or in laboratory studies. 

As seen earlier in this chapter, the oxidation of organics produces a variety of free radicals, some of which can form peroxyacyl nitrates. For example, acetaldehyde is a classic precursor to the PAN through the following reaction sequence ... 

TABLE 6.20 Structures and Commonly Used Names for Some Peroxyacyl Nitrates Found in the Atmosphere and / or in Laboratory Studies... 

For a detailed treatment of peroxyacyl nitrates, see the recent reviews by Gaffney et al., 1989 Roberts, 1990 Altshuller, 1993 and Kleindienst, 1994. 

Grosjean, D., E. L. Williams, II, and E. Grosjean, Peroxyacyl Nitrates at Southern California Mountain Forest Locations, Environ. Sci. TechnoL, 27, 110-121 (1993b). 

Grosjean, D E. Grosjean, and E. L. Williams, Thermal Decomposition of C3-Substituted Peroxyacyl Nitrates, Res. Chem. Interned., 20, 447-461 (1994b). 

The formation and fate of peroxyacyl nitrates, RC(0)00N02, were discussed in Chapter 6.1. These compounds are almost universally measured using gas chromatography with electron capture detection (GC-ECD), although a luminol chemiluminescence detector has also been used in which PAN is thermally decomposed to N02 at the end of the column and the N02 measured (Burkhardt et al., 1988 Blanchard et al., 1990 Gaffney et al., 1998). In polluted atmospheres where the concentrations are higher, FTIR has also been used (Table 11.2). For a summary of methods, see reviews by Gaffney et al. (1989) and Kleindienst (1994). 

In short, a variety of alkyl nitrates are present in air, but at relatively small concentrations compared to the peroxyacyl nitrates and to NO,. 

Gaffney, J. S., N. A. Marley, and E. W. Prestbo, Peroxyacyl Nitrates (PANs) Their Physical and Chemical Properties, in The Handbook of Environmental Chemistry (O. Hutzinger, Ed.), Vol. 4, Part B, pp. 4-38, Springer-Verlag, Berlin, 1989. 

Reaction with NOz to form the peroxyacyl nitrate CFC12C(0)00N02 can also occur. 

Peroxyacyl nitrate (CH3C(0)00N02) PAN Nitrophenol NPHN... 

Substance or subclass Ozone or oxidant Peroxyacyl nitrate Formaldehyde Aerosol particles Eye irritation Plant damage Averaged response... 

The worst irritants in photochemical smogs are peroxyacyl nitrates, PAN. They produce singlet oxygen when they hydrolyze, and this may account for their biological action. Other objectionable components of photochemical smogs include aldehydes, organic hydroperoxides (ROOH), and peroxynitrates. 

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