Peroxyacylnitrates PANs

Phlogiston a material once thought to be an element responsible for combustion Phospholipid lipid containing phosphorus derived from phosphoric acid Photochemical Oxidants air pollutants produced when hydrocarbons, nitrogen oxides, and other chemicals react under the influence of sunlight, for example, ozone, peroxyacylnitrates (PAN)... 

Carbon monoxide is oxidized in the troposphere ((133) and (134)). With a high concentration of nitric oxide in the troposphere, reactions (135) and (136) take place. This sequence is a formation of ozone catalyzed by nitric oxide. If the nitric oxide concentration is too low, the perhydryl radicals decompose ozone to form hydroxyl radicals (136). Ozone and peroxyacylnitrates PAN are the major toxins of smog. Peroxyacylnitrates are formed from aldehydes in a reaction catalyzed by nitric oxide. 

Peroxyacylnitrate (PAN) is one of the components of smog. It is a compound of C, H, N, and O. Determine the percent composition of oxygen and the empirical formula from the following percent composition by mass 19.8 percent C, 2.50 percent H, 11.6 percent... 

Photochemical oxidants are atmospheric pollutants produced by a series of reactions between hydrocarbons and oxides of nitrogen in the presence of sunlight. The recognized photochemical oxidants that have been measured in ambient air are ozone, the peroxyacylnitrates (mostly as PAN), and hydrogen peroxide. ... 

The peroxyacylnitrates were first identified in % as the primary cause of the undersurface glazing and bronzing on some broadleaved plants. PAN has since been implicated in numerous pollution episodes in southern California. Its importance in other metropolitan and rural areas in the United States and throughout the world is uncertain, although symptoms have been reported elsewhere. The reason is that oxidant concentrations in other parts of the world are much lower than those reported in California, and monitoring networks have not looked for PAN or its homologues. The report by Penkett et al. was the first to come from Europe. 

The peroxyacylnitrates are the most phytotoxic of the known photochemical oxidants. The toxicity of the known homologues is inversely correlated with molecular weight. PAN is the best known and has been studied most, because of its usual presence in photochemical atmospheres. 

Chemical Basis of Toxicity The toxicity of the peroxyacylnitrates to plants can be the result of several different processes. Any chemical explanation of the toxicity will have to explain the increasing toxicity of the series PAN, PPN, PBN, and PBzN. Three hypotheses have been tested the more toxic homologues are more readily taken up by the... 

These properties may account for their biological behaviour. Peroxyacylnitrates — mainly represented by peroxyacetylnitrate, indicated as PAN — originate in the atmosphere over towns and industrial areas, through a mechanism not fully clarified, from olefins, and other hydrocarbons (car exhausts, fuel from car tank evaporation, gas formed in the refineries of crude oil) under photochemical conditions by NOx in the presence of O2 (Stephen, 1969). 

Data have also been obtained for various other peroxyacylnitrate species formed from a number of different VOCs. Structure-reactivity relationships for the thermal stability of PAN type species have been established which provide the needed information for assessing the transport of NOy in this form, and also the relationships required in order to estimate the relative rates of the reactions of RO2 with NO (leading to ozone production) and NO2 (leading to the PAN reservoirs) have been established. Although the peroxyacylnitrates are the most stable, other peroxynitrates could also be significant reservoirs for NOx in the coldest regions of the troposphere. 

Yes, it is very bad for the respiratory system. It is generated on hot sunny summer days when the sunlight acts on mixtures of hydrocarbons and nitrogen oxides emitted from car exhausts to form peroxyacylnitrates (or PANs, with general formula RCOOONO2 with R = alkyl). These are the compounds which typically make your eyes water on a hot summer s day in city streets. Ozone is formed from them when they decompose. 

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