Hydrocarbons, hydrocarbon arenes

Carbon atoms can also form cyclic compounds. Aromatic hydrocarbons (arenes), of which benzene is the parent, consist of a cyclic arrangement of formally unsaturated carbons, which, however, give a stabilized (in contrast to their hypothetical cyclopolyenes), delocalized system. 

Another name for aromatic hydrocarbons is arenes Arenes have properties that are much different from alkanes alkenes and alkynes The most important aromatic hydrocarbon... 

Benzene is the parent of a class of hydrocarbons called arenes, or aro matic hydrocarbons... 

Together with glutathione conjugation, hydration is a major pathway in the inactivation and detoxification of arene oxides. Exceptions to this rule will be treated when discussing polycyclic aromatic hydrocarbons. Arene oxides are good substrates for microsomal EH, as evidenced in Table 10.1, where hydration of selected arene oxides, alkene oxides, and cy-cloalkene oxides by purified rat liver epoxide hydrolase is compared. The hy- ... 

Aromatic hydrocarbons (or arenes) are a subset of the larger set of hydrocarbons and the simplest of these Is benzene. It is a colourless liquid and has a molecular formula of C H. The molecular formula shows that benzene Is deficient in hydrogen atoms and suggests that It Is an unsaturated hydrocarbon. 

The Heck reaction is a C-C coupling reaction where an unsaturated hydrocarbon or arene halide/triflate/sulfonate reacts with an alkene in presence of a base and Pd(0) catalyst so as to form a substituted alkene. Kaufmann et al. showed that the Heck reaction carried out in presence of ILs such as tetra-alkyl ammonium and phosphonium salts without the phosphine ligands, resulted in high yields of product. They attributed the activity to the stabilizing effect of ammonium and phosphonium salts on Pd(0) species. Carmichael et al. used ionic liquids containing either A,A -dialkylimidazolium and A-alkylpyridinium cations with anions such as halide, hexafluorophosphate or tetrafiuoroborate to carry out reactions of aryl halide and benzoic anhydride with ethyl and butyl acrylates in presence of Pd catalyst. An example of iodobenzene reacting with ethyl acrylate to give trans-et vy cinnamate is shown in Scheme 14. 

The generic name of monocyclic and polycyclic aromatic hydrocarbons is arene . 

The so-called aromatic hydrocarbons, or arenes, are cyclic unsaturated compounds that have such strikingly different chemical properties from conjugated alkenes (polyenes) that it is convenient to consider them as a separate class of hydrocarbon. The simplest member is benzene, C6H6, which frequently is represented as a cyclic conjugated molecule of three single and three double carbon-carbon bonds. Actually, all the carbon-carbon bonds are equivalent (see Chapter 1) but it is convenient to represent the structure in the manner shown ... 

The pleasant odors of the derivatives of many arenes is the origin of the name aromatic hydrocarbons. The arenes themselves generally are quite toxic some are carcinogenic and inhalation of their vapors should be avoided. The volatile arenes are highly flammable and burn with a luminous sooty flame, in contrast to alkanes and alkenes, which usually burn with a bluish flame leaving little carbon residue. 

The synthesis of aromatic hydrocarbons (arenes) is for convenience organised under the following five headings. 

Bis(tj6-arene) complexes, with chromium hydrocarbon-substituted arenes, 5, 338 with peripheral heteroatoms, 5, 340 with ring integral heteroatoms, 5, 339 theoretical considerations, 5, 338 Bis(l,2-arenedithiolato) compounds, in mono-Cp Ti(IV) complexes, 4, 503-504... 

Hydrocarbon bridging ligands in dinuclear Ru complexes rj3-enyl ligands, 6, 698 hydrocarbon rj6-arene ligands, 6, 709 hydrocarbon rj4-diene ligands, 6, 700 hydrocarbon rj5-dienyl ligands, 6, 704 cr-bonded ligands, 6, 693... 

Klarner et al. undertook detailed studies of the host/guest relationships between molecular tweezers formed from condensed hydrocarbon arenes and symmetrically and asymmetrically dendryl-substituted viologens - with a 4,4 -bi-pyridinium core acting as -electron acceptor and a Frechet-type dendron as 71-electron donor (Fig. 6.23). The strong fluorescence of the 1,3-dimethylenoxyben-zene units of the Frechet dendron is quenched as a result of the donor/acceptor interaction. Accordingly, in dichloromethane solution the 4,4 -bipyridinium core... 

Much as benzene and phenyl are the simplest aromatic hydrocarbon or arene and aryl group respectively, methane and methyl are the simplest aliphatic hydrocarbon or alkane and alkyl group respectively. The resonance energy of the various halobenzenes may be identified as the negative of the exothermicity of reaction 34. 

Benzene (CeH ) is the simplest aromatic hydrocarbon (or arene). Since its isolation by Michael Faraday from the oily residue remaining in the illuminating gas lines in London in 1825, it has been recognized as an unusual compound. Based on the calculation introduced in Section 10.2, benzene has four degrees of unsaturation, making it a highly unsaturated hydrocarbon. But, whereas unsaturated hydrocarbons such as alkenes, alkynes, and dienes readily undergo addition reactions, benzene does not. For example, bromine adds to ethylene to form a dibromide, but benzene is inert under similar conditions. 

Relatively few arene dioxides and trioxides have been reported from PAHs. Arene dioxides in the naphthalene 152, 154, 155 and anthracene 157 series have been formed in good yield by direct epoxidation of the parent hydrocarbon. These arene dioxides 152, 154, 155, and 157 were formed by MCPBA epoxidation... 

Another carcinogenic polycyclic aromatic hydrocarbon, 7,l2-dimethylben/.lajanthracene. also forms covalent adducts with nucleic acids (RNA)."" The ultimate carcinogenic reactive species apparently is the S.6-oxidc that results from epoxidation of the 5,6-double bond in this aromatic hydrocarbon. The arene oxide intermediate binds covalently to guanosinc residues of RNA to yield the two adducts. 

Aromatic hydrocarbons (arenes) unsaturated compounds hexagonal ring structure single and multiple fused rings... 

Britt, PR, A.C. Buchanan iii, and C.V. Owens Jr Eormation of nitrogen containing polycyclic aromatic hydrocarbons (aza-arenes) from the pyrolysis of Amadori componnds 55th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 55, Paper No. 46, 2001, p. 48. 

Grimmer, G., K.W. Naujack, and G. Dettbarn Gas chromatographic determination of polycyclic aromatic hydrocarbons, aza-arenes, aromatic amines in the particle and vapor phase of mainstream and sidestream smoke of cigarettes Intemat. Exptl. Toxicol. Symp. on Passive Smoking, Essen ERG (1986) pp. 1-19 Toxicol. Lett. 35 (1987) 117-124. 

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