Transformation Of Pyrene Research Articles

Photochemical transformation of pyrene vapor deposited on eleven subfractions of a high-carbon coal stack ash

A high-carbon coal stack ash has been separated by particle size and then by composition, into strongly magnetic, weakly magnetic, “nonmagnetic” mineral, heavy carbon and light carbon fractions. Eleven of these fractions have been characterized by bulk iron and carbon analyses and BET surface area determinations. The photochemical transformation of pyrene, deposited from the vapor phase onto these eleven ash fractions, has been studied. Appreciable phototransformation of adsorbed pyrene was observed for only three fractions; in those fractions, the bulk percentage of carbon (0.4–0.7%) and the specific surface area (0.50–0.68 m2/g) were both very low. For all fractions having bulk carbon percentages ≥ 4% and specific surface areas ≥ 2.85 m2/g, no detectable phototransformation of adsorbed pyrene was observed. There was no discernible correlation of photochemical reactivity of adsorbed pyrene with the iron content of the ash fractions. In general, the specific surface area of the fractions increased with increased carbon content; two different forms of carbon having different surface areas were observed.

Oxidations by methyl(trifluoromethyl)dioxirane. 4.1 oxyfunctionalization of aromatic hydrocarbons

By using the title dioxirane ( 1a), naphthalene ( 2), phenanthrene ( 3), and anthracene ( 4) have been converted into anti-naphthalene-1,2;3,4-dioxide ( 2′), phenonthrene-9,10-oxide ( 3′), and anthraquinone ( 4′), respectively, in high yield and under mild conditions. However, the transformation of pyrene ( 5) - an higher homologue of the polycyclic aromatic hydrocarbon series - into the corresponding arene oxide was found to procced much less effectively.

Photochemical transformation of pyrene and benzo[a]pyrene vapor-deposited on eight coal stack ashes

The photochemical decomposition of pyrene and benzo(a)pyrene, as adsorbates deposited from the vapor phase, has been examined on eight coal stack ashes of diverse origin and properties. Similar studies using alumina, silica gel, controlled-porosity glass, and graphite adsorbents also have been performed. Phototransformation of the adsorbates proceeds more slowly on any of the ash substrates than on alumina, silica, or glass surfaces. Those ashes relatively high in carbon and/or iron content are especially effective at suppressing photodegradation of adsorbed pyrene or benzo(a)pyrene. This relationship appears, at least in part, to be associated with the relatively dark colors of those ashes. The apparent acidity of ash surfaces does not appear to be related to the rate of phototransformation of adsorbed polycyclic aromatic hydrocarbons. 40 references, 1 figure, 5 tables.

The effect of nitrogen dioxide on the photochemical and nonphotochemical degradation of pyrene and benzo[a]pyrene adsorbed on coal fly ash

Nitration by NO 2 of pyrene or benzo[a]pyrene adsorbed from the vapor phase onto six coal ashes, alumina, and silica substrates is not observed if the NO 2 is thoroughly purged of nitric acid. Also, the photochemical transformation of pyrene or benzo[a]pyrene adsorbed on these substrates is not detectably influenced by the presence of nitric acid-free NO 2. Photochemical production of nitro derivatives of adsorbed polycyclic aromatic hydrocarbons in the presence of NO 2 does not appear to be a significant process unless appreciable concentrations of nitric acid, or perhaps strong oxidants such as ozone, also are present.

Mutagenicity of the sunlight-exposed sample of pyrene in Salmonella typhimurium TA98.

In addition to chemical and biochemical transformations of PAHs in simulated conditions, it has been reported that PAHs associated with airborne particles are readily photooxidized in real atmosphere. These studies prompted us to investigate a relation between the photodegradation of PAHs in the real atmospheric environment and the resultant mutagenicity of their degradation products. In this paper, the authors describe the transformation of pyrene into directly active mutagen following exposure to sunlight in the real atmosphere and the presence of directly active mutagens in the oxygenated and acidic fractions of the exposed sample of pyrene.