Polycyclic, polynuclear aromatic structures

Polycyclic aromatic hydrocarbons (PAHs, sometimes also called polynuclear aromatics, PNA) are a hazardous class of widespread pollutants. The parent structures of the common PAHs are shown in Fig. 4 and the alkylated homologs are generally minor in combustion emissions. PAHs are produced by all natural combustion processes (e.g., wild fires) and from anthropogenic activity such as fossil fuels combustion, biomass burning, chemical manufacturing, petroleum refining, metallurgical processes, coal utilization, tar production, etc. [6,9,15,18, 20,24,131-139]. 

Three studies on radical cations discuss the characterization of polynuclear aromatic radical cation salts as organic metals (8), the reactions of cation radicals with neutral radicals (9), and the magnetic-electrical properties of perfluoroaromatic radical-cation salts (10). Chapters on polynuclear aromatic compounds in nonvolatile petroleum products (II) and in coal-based materials (12) present reviews of the subject and new findings. The remaining chapters in this book discuss the thermal conversion of polynuclear aromatic compounds to carbon (13), the nitration of pyrene by mixtures of N02 and N204 (14), the spectra, structures, and chromatographic retention times of large polycyclic aromatic hydrocarbons (15), the desulfurization of polynuclear thiophenes correlated with tt electron densities (16) and simple theoretical methods to predict and correlate polynuclear benzenoid aromatic hydrocarbon reactivities (IT). 

L.V. Szentpaly Theoretical model of activation of carcinogenic polycyclic benzenoid aromatic hydrocarbons. Possible new classes of carcinogenic aromatic hydrocarbons J. Molecul. Structure (Theochem) 148 (1986) 141-152 Structure-property relationships in polycyclic aromatics Symposium on Chem. Polynuclear Aromatic Hydrocarbons, Am. Chem. Soc. (1986) 849-855. 

Indisputably, the most significant contributions to polycyclic aromatic hydrocarbons originated with Clar at the beginning of this decade. His efforts were published in the journal series Polynuclear Aromatic Hydrocarbons and/or Aromatic Hydrocarbons [27] as well as in an excellent two volume series, Polycyclic Hydrocarbons, [la] which provided a comprehensive look at hydrocarbon diversity. Not only did he and his coworkers produce an exceeding number of new carbon-rich structures, but his adaptation and development of new synthetic methodologies allowed confirmation of structure as well as improved yields to provide sufficient quantities for physical property studies. Clar and coworkers continued their work well into the latter parts of the 20th century. His early work focused on benzo-, naphtho-, and anthraceno-derivatives of anthracene and phenanthrene [la]. 

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