Aromatic hydrocarbons structure

McCarthy, J.F., Jimenez, B.D., Barbee, T. (1985) Effect of dissolved humic material on accumulation of polycyclic aromatic hydrocarbons structure-activity relationships. Aqua. Toxicol. 7, 15-24. 

Sovadinova, I., Blaha, L., Janosek, J., Hilscherova, K., Giesy, J.P., Jones, P.D. and Holoubek, I. (2006) Cytotoxicity and aryl hydrocarbon receptor-mediated activity of N-heterocydic polycyclic aromatic hydrocarbons structure-activity relationships. Environmental Toxicology and Chemistry, 25, 1291-1297. 

Sander, L.C. and Wise, S.A., Polycyclic Aromatic Hydrocarbon Structure Index, Natl. Inst. Stand. Technol. Spec. Publ. 922. U.S. Government Printing Office, Washington, 1997. 

The reference values used to calculate C were Et, 37 r/, 1. The equilibrium constant decreases with increasing solvent polarity and decreases with increasing metallic ion size. It also seems to decrease with increasing aromatic hydrocarbon size, but the descriptor ric is ineffective. In view of the different temperatures and methods of determination of the Ke values, the goodness of fit is satisfactory. More variation in aromatic hydrocarbon structure is needed to determine its effect on K.. 

Because of this wealth of data, a two-dimensional solution, employing only zones of reflections and corresponding projections of the structure, is often used. Many of the aromatic hydrocarbon structures, with their planar or nearly planar molecules, have been solved in this way. With... 

Sovadinova I, Blaha L, Janosek J, Hilscherova K, Giesy JP, Jones PD, et al. Cytotoxicity and aryl hydrocarbon receptor-mediated activity of w-heterocyclic polycyclic aromatic hydrocarbons Structure-activity relationships. Environ Toxicol Chem 2006 25 1291-7. 

Palit, 1954), didodecyldimethylammonium halides, and di(2-ethylhexyl)ammo-nium halides. Since many POE nonionics are soluble in aliphatic and aromatic hydrocarbons, structural limitations on the use of these materials for this purpose are not as restrictive as in the case of ionics. Polyanionic soaps made by copolymerization of maleic anhydride and dodecyl (or octadecyl) vinyl ether followed by treatment with morpholine have been used to solubilize water into nonaqueous solvents (Ito, 1964). 

The substances for which this phenomenon has been observed are invariably polycyclic aromatic hydrocarbon structures. No exciplex formation has been reported in the literature to involve drug molecules, but this remains a possibility in concentrated solution or perhaps in solid-state mixtures. The consequences of exciplex formation are a radiative or nonradiative return to the ground state without chemical change, or electron transfer leading to chemical reaction of the drug, the quencher, or both. Many photoaddition processes are postulated to proceed via exciplex formation with the quencher molecule becoming chemically bound. 

Cancer was first identified in the late eighteenth century, after observation of its incidence in patients who were chimney sweepers in the UK, which established the interrelation between chemicals and the disease (exposure to soot, coal tars and benzene). Later, the carcinogenic potency of tar was shown to be related to its polynuclear aromatic hydrocarbon structure. 

Sander LC, Wise SA. Polycyclic aromatic hydrocarbon structure index, Natl Inst Stand Tech Spec Publ 922. Washington, DC U.S. Government Printing Office 1997. 

The biological properties of dioxin include an ability to bind to a protein known as the AH (aromatic hydrocarbon) receptor Dioxin IS not a hydrocarbon but it shares a certain structural property with aromatic hydrocarbons Try constructing molecular models of dioxin and anthracene to see these similarities... 

Fig. 12. A, Schematic representation of parallel arrays of polynuclear aromatic hydrocarbon molecules in a mesophase sphere. B, a) isolated mesophasc spheres in an isotropic fluid pitch matrix b) coalescence of mesophase c) structure of semi-coke after phase inversion and solidification.

Mochida, I., Shimizu, K.., Korai, Y., Otsuka, H. and Fujiyama, S., Structure and carbonization properties of pitches produced catalytically from aromatic hydrocarbons with HF/BFj, Carbon, 1988, 26(6), 843 852. 

Radical cations can be derived from aromatic hydrocarbons or alkenes by one-electron oxidation. Antimony trichloride and pentachloride are among the chemical oxidants that have been used. Photodissociation or y-radiation can generate radical cations from aromatic hydrocarbons. Most radical cations derived from hydrocarbons have limited stability, but EPR spectral parameters have permitted structural characterization. The radical cations can be generated electrochemically, and some oxidation potentials are included in Table 12.1. The potentials correlate with the HOMO levels of the hydrocarbons. The higher the HOMO, the more easily oxidized is the hydrocarbon. 

In general, the most stable resonance structure for a polycyclic aromatic hydrocarbon is the one with the greatest number of rings that correspond to Kekule formulations of benzene. Naphthalene provides a fairly typical exanple ... 

It is convenient to divide aromatic hydrocarbons into two groups (I) benzene derivatives, and (2) polynuclear aromatics containing multiring structures. 

Benzene derivatives. Tbe nomenclature is a combination of the lUPAC system and traditional names. Many of the derivatives are named by the substituent group appearing as the prefbt. These may be considered a subclass of the aliphatic-aromatic hydrocarbon family, which contains both aliphatic and aromatic units in its structures. Thus, alkylbenzenes are made up of a benzene ring and alkane units alkenylbenzenes are Composed of a benzene ring and alkene units and alkynylbenzenes comprise a benzene ring and alkyne units. Examples of alkylbenzenes include... 

Polynuclear aromatic hydrocarbons. These consist of a variety of complex structures made up of aromatic rings alone, or combinations of aliphatic rings, aromatic rings, and aliphatic chains, etc. One such class of compounds is biphenyl and its derivatives, in which two benzene rings are connected by a single C — C linkage. The structural formula of biphenyl (or phenylbenzene) is... 

Although many of the aromatic compounds based on benzene have pleasant odors, they are usually toxic, and some are carcinogenic. Volatile aromatic hydrocarbons are highly flammable and burn with a luminous, sooty flame. The effects of molecular size (in simple arenes as well as in substituted aromatics) and of molecular symmetry (e.g., xylene isomers) are noticeable in physical properties [48, p. 212 49, p. 375 50, p. 41]. Since the hybrid bonds of benzene rings are as stable as the single bonds in alkanes, aromatic compounds can participate in chemical reactions without disrupting the ring structure. 

Binuclear aromatic hydrocarbons are found in heavier fractions than naphtha. Trinuclear and polynuclear aromatic hydrocarbons, in combination with heterocyclic compounds, are major constituents of heavy crudes and crude residues. Asphaltenes are a complex mixture of aromatic and heterocyclic compounds. The nature and structure of some of these compounds have been investigated. The following are representative examples of some aromatic compounds found in crude oils ... 

Problem 13.11 Propose a structure for an aromatic hydrocarbon, CnH16, that has the following... 

---