Polycyclic aromatic hydrocarbons mechanism

Dreibelbis, W.G, Ealy, J.A. Porter, W.E. (1982) Industrial hygiene monitoring for evaluation of employee exposure and control measures in coal conversion program at Oak Ridge National Laboratory. In Cooke, M. Dennis, A.J., eds, Polycyclic Aromatic Hydrocarbons Mechanisms, Methods and Metabolism, Proceedings of the Eight International Symposium, Columbus, OH, Battelle Press, pp. 351-361... 

Major unknowns in the mechanism by which a hydrocarbon fuel bums concern the pyrosynthesis reactions that lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and soot and the oxidation chemistry of atoms other than carbon and hydrogen (heteroatoms) in the fuel, particularly nitrogen, sulfur, and halogens. 

FIGURE 7.9 Mechanism of formation of polycyclic aromatic hydrocarbons (PAHs) during combustion. 

Cavalier E, E Rogan (1998) Mechanisms of tumor initiation by polycyclic aromatic hydrocarbons in mammals. Handbook Environ Chem 3J 82-117. 

Sutherland JB, E Rafii, AA Kahn, CE Cerniglia (1995) Mechanisms of polycyclic aromatic hydrocarbon degradation. In Microbial transformation and degradation of toxic organic chemicals (Eds LY Young and CE Cerniglia), pp. 269-306. Wiley-Liss, New York. 

Rabinowitz, J. R., and S. B. Little. 1994. Comparison of Quantum-Mechanical Methods to Compute the Biologically Relevant Reactivities of Cyclopenta-Polycyclic Aromatic-Hydrocarbons. Inti. J. Quant. Chem. 52, 681. 

Hydrocarbon Microbiology biodegradation mechanisms of oil products (gasoline, kerosene, diesel, etc.), pyrolysis, polycyclic aromatic hydrocarbons, chlorinated solvents, and ether fuels refining processes (e.g., oil product microbial desulfurization) and oil production processes (e.g., bacterial corrosion). 

Figure 7. Steric model proposed by Jerina, et al. for the catalytic binding site of cytochrome P-450c (P-448) to account for the stereoselective metabolism of polycyclic aromatic hydrocarbons (48). The boundary should be enlarged in the directions shown to accommodate substrates whose mechanism of stereoselective oxygenation does not fit the steric model originally proposed.

Covalent binding of chemical carcinogens to cellular macromolecules, DNA, RNA and protein, is wel1-accepted to be the first step in the tumor initiation process ( 1, 2). Most carcinogens, including polycyclic aromatic hydrocarbons (PAH), require metabolic activation to produce the ultimate electrophilic species which react with cellular macromolecules. Understanding the mechanisms of activation and the enzymes which catalyze them is critical to elucidating the tumor initiation process. 

Various organic molecules are used as photosensitizers in liquid-phase reactions, for example, anthraquinones, aryl ketones, polycyclic aromatic hydrocarbons, dyes, etc. The following mechanism, as the most probable, was suggested for the initiation by the organic photosensitizer Q with the aromatic ring [204-208] ... 

Cavalieri, E., R. Roth, E. Rogan C. Grandjean, and J. Althoff. 1978. Mechanisms of tumor initiation by polycyclic aromatic hydrocarbons. Pages 273-284 in P.W. Jones and R.I. Freudenthal (eds.). Carcinogenesis — A Comprehensive Survey. Vol. 3. Polynuclear Aromatic Hydrocarbons Second International Symposium on Analysts, Chemistry, and Biology. Raven Press, New York. 

Yan, L.S. 1985. Study of the carcinogenic mechanism for polycyclic aromatic hydrocarbons — extended bay region theory and its quantitative model. Carcinogenesis 6 1-6. 

Several improved stationary phase materials have been synthesized for reversed-phase liquid chromatography. One material is vinyl alcohol copolymer gel. This stationary phase is quite polar and chemically very stable however, it demonstrated a strong retention capacity for polycyclic aromatic hydrocarbons.45 9 Although stable octadecyl- and octyl-bonded silica gels have been synthesized from pure silica gel50,51 and are now commercially available, such an optimization system has not yet been built. Further experiments are required to elucidate the retention mechanism, and to systematize it within the context of instrumentation. 

In the pH range of 5 - 10, H20-catalyzed hydrolysis is the predominant mechanism (see Fig. 10.11, Pathway b), resulting in the formation of the (8R,9R)-dihydrodiol (10.133, Fig. 10.30). Thus, aflatoxin B1 exo-8,9-epoxide is possibly the most reactive oxirane of biological relevance. Such an extreme reactivity is mostly due to the electronic influence of 0(7), as also influenced by stereolectronic factors, i.e., the difference between the exo- and endo-epoxides. The structural and mechanistic analogies with the dihydro-diol epoxides of polycyclic aromatic hydrocarbons (Sect. 10.4.4) are worth noting. 

The extension of direct photooxygenation reactions to polycyclic aromatic hydrocarbons as well as to aryl-substituted carbocyclic and heterocyclic pentadienes is due to the (exclusively preparative) work of Dufraisse and Etienne.5-20-29 Investigations on the mechanisms of these reactions were made by Bowen,2 Livingston,3 and Cherkasov and Vember.30-31... 

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