Chemistry aromatic hydrocarbons

Hydrocarbons are divided into two mam classes aliphatic and aromatic This classifi cation dates from the nineteenth century when organic chemistry was devoted almost entirely to the study of materials from natural sources and terms were coined that reflected a substance s origin Two sources were fats and oils and the word aliphatic was derived from the Greek word aleiphar meaning ( fat ) Aromatic hydrocarbons irre spective of their own odor were typically obtained by chemical treatment of pleasant smelling plant extracts... 

In general, peroxomonosulfates have fewer uses in organic chemistry than peroxodisulfates. However, the triple salt is used for oxidizing ketones (qv) to dioxiranes (7) (71,72), which in turn are useful oxidants in organic chemistry. Acetone in water is oxidized by triple salt to dimethyldioxirane, which in turn oxidizes alkenes to epoxides, polycycHc aromatic hydrocarbons to oxides and diones, amines to nitro compounds, sulfides to sulfoxides, phosphines to phosphine oxides, and alkanes to alcohols or carbonyl compounds. 

Epoxides are often encountered in nature, both as intermediates in key biosynthetic pathways and as secondary metabolites. The selective epoxidation of squa-lene, resulting in 2,3-squalene oxide, for example, is the prelude to the remarkable olefin oligomerization cascade that creates the steroid nucleus [7]. Tetrahydrodiols, the ultimate products of metabolism of polycyclic aromatic hydrocarbons, bind to the nucleic acids of mammalian cells and are implicated in carcinogenesis [8], In organic synthesis, epoxides are invaluable building blocks for introduction of diverse functionality into the hydrocarbon backbone in a 1,2-fashion. It is therefore not surprising that chemistry of epoxides has received much attention [9]. 

Harvey R. G. Polycyclic Aromatic Hydrocarbons Chemistry and Carcinogenesis, Cambridge University Press, Cambridge, 1991. 

Explicit mechanisms attempt to include all nonmethane hydrocarbons believed present in the system with an explicit representation of their known chemical reactions. Atmospheric simulation experiments with controlled NMHC concentrations can be used to develop explicit mechanisms. Examples of these are Leone and Seinfeld (164), Hough (165) and Atkinson et al (169). Rate constants for homogeneous (gas-phase) reactions and photolytic processes are fairly well established for many NMHC. Most of the lower alkanes and alkenes have been extensively studied, and the reactions of the higher family members, although little studied, should be comparable to the lower members of the family. Terpenes and aromatic hydrocarbons, on the other hand, are still inadequately understood, in spite of considerable experimental effort. Parameterization of NMHC chemistry results when NMHC s known to be present in the atmosphere are not explicitly incorporated into the mechanism, but rather are assigned to augment the concentration of NMHC s of similar chemical nature which the... 

Wall Loss of Oxidation Products. It is known that some classes of hydrocarbons (the higher terpenes, for instance) are prolific aerosol formers when subjected to atmospheric oxidation. Other classes, aromatic hydrocarbons for instance, although they do not form large amounts of suspended aerosol, have been shown to lose (at least under some conditions) large amounts of oxidation products to the reaction vessel walls. The fate of these oxidation products in the open atmosphere remains open to question, as does the extent to which they continue to participate in gas-phase chemistry (187). 

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. 

Standardization. Standardization in analytical chemistry, in which standards are used to relate the instrument signal to compound concentration, is the critical function for determining the relative concentrations of species In a wide variety of matrices. Environmental Standard Reference Materials (SRM s) have been developed for various polynuclear aromatic hydrocarbons (PAH s). Information on SRM s can be obtained from the Office of Standard Reference Materials, National Bureau of Standards, Gaithersburg, MD 20899. Summarized in Table VII, these SRM s range from "pure compounds" in aqueous and organic solvents to "natural" matrices such as shale oil and urban and diesel particulate materials. 

De Voogt, R (1996). Ecotoxicology of chlorinated aromatic hydrocarbons. In Chlorinated Organic Micropollutants, No 6 in series Issues in Environmental Science and Technology. R.E. Hester and R.M. Harrison (Eds.) Royal Society of Chemistry 89-112. 

Sander and wise have proposed a test method to determine the bonding chemistry used to prepare octadecylsiloxane column packings based on the relative retention of three polycyclic aromatic hydrocarbons, benzo[a]pyrene (BaP), phenanthro-phenanthrene (PhPh), and l,2 3,4 5,6 7,8-tetrabenzonaphthalene (TBN) eluted with the mobile phase acetonitrile-water (85 15) [52,67,199,210]. On monomeric phases the test solutes elute in the... 

In connection with the chemistry of the reactive transient species, nitrene, the chemistry of azepines is well documented u. Also, the chemistry of oxepins has been widely developed due to the recent interest in the valence isomerization between benzene oxide and oxepin and in the metabolism of aromatic hydrocarbons 2). In sharp contrast to these two heteropins, the chemistry of thiepins still remains an unexplored field because of the pronounced thermal instability of the thiepin ring due to ready sulfur extrusion. Although several thiepin derivatives annelated with aromatic ring(s) have been synthesized, the parent thiepin has never been characterized even as a transient species3). 

This chemistry becomes synthetically useful when one of the isomeric palladium intermediates can react with a neighboring substituent and the other isomer cannot. Thus, we have taken advantage of this effect to synthesize a range of polycyclic aromatic hydrocarbons by Pd migration and subsequent arylation (Scheme 24).21 This provides a unique way to form new carbon-carbon bonds in a location remote from the original functionality. 

Although the correlation between structural properties of aromatic hydrocarbons and their carcinogenic properties proved to be much more complicated than was hoped, this type of calculation opened the door to the application of quantum chemistry to biological systems. The calculations are applied not only to cancer-related problems, but also to the study of amino acids, peptides, nucleotides, and other than anti-cancer therapeutic agents. 

LaVoie, E. Tulley, L. Bedenko, V. Hoffmann, D. In "Polynuclear Aromatic Hydrocarbons Chemistry and Biological Effects" Bjorseth, A. Dennis, A.J., Eds. Battelle Columbus, Ohio, 1979 p. 1041. 

Newman, M.S. In "Polynuclear Aromatic Hydrocarbons Chemistry, Metabolism and Carcinogenesis" Freudenthal, R. Jones, P.W., Eds. Raven Press New York, 1976, pp. 203-7. 

M. LeBreton, P. R. in "Proceedings of the Ninth International Symposium on Polynuclear Aromatic Hydrocarbons, Polynuclear Aromatic Hydrocarbons Chemistry, Characterization and... 

Cavalieri, E. Rogan, E. In "Polynuclear Aromatic Hydrocarbons Physical and Biological Chemistry" Cooke, M. Dennis, A.J. Fisher, G.L., Eds. Battelle Press Columbus, Ohio, 1982 pp. 145-155. 

In "Polynuclear Aromatic Hydrocarbons. Third International Symposium on Chemistry and Biology—Carcinogenesis and Mutagenesis" Ann Arbor Science Publishers Ann Arbor, Mich.,... 

Cramer J (1973) Model of the circulation of DDT on Earth. Atmospheric Environment 7 241-256 Cziudaj G (2005) Die Rolle der Ozeane bei der globalen Verteilung von organischen Schadstoffen PCB als Modellsubstanzen. PhD thesis, Christian Albrechts University Kiel Dachs J, Bayona JM, Fowler SW, Miquel J, Albaiges J (1996) Vertical fluxes of polycyclic aromatic hydrocarbons and organochlorine compounds in the western Alboran Sea (southwestern Mediterranean). Marine Chemistry 52 75-86... 

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