Cyclic hydrocarbons unsaturated

Aromaticity is usually described in MO terminology. Cyclic structures that have a particularly stable arrangement of occupied 7t molecular orbitals are called aromatic. A simple expression of the relationship between an MO description of stmcture and aromaticity is known as the Hiickel rule. It is derived from Huckel molecular orbital (HMO) theory and states that planar monocyclic completely conjugated hydrocarbons will be aromatic when the ring contains 4n + 2 n electrons. HMO calculations assign the n-orbital energies of the cyclic unsaturated systems of ring size 3-9 as shown in Fig. 9.1. (See Chapter 1, Section 1.4, p. 31, to review HMO theory.)... 

The structural formulas of ethylene and propylene are shown in Figure 18-12. Cyclic hydrocarbons also can involve double bonds. The structural formula of a cyclic unsaturated hydrocarbon is shown also in Figure 18-12. 

Aromatic hydrocarbons are unsaturated cyclic compounds that are resistant to addition reactions. The aromatic hydrocarbons derive their name from the distinctive odors they exhibited when discovered. Benzene is the most important aromatic compound. Because many other aromatic compounds are derived from benzene, it can be considered the parent of other aromatic compounds. Benzene molecular formula is... 

Antipyretic substance that reduces fever Aromatic Hydrocarbon an unsaturated cyclic hydrocarbon that does not readily undergo additional reaction, benzene and related compounds... 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

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 ligand-exchange method is the most used method in the synthesis of ji-complexes. The examples of such compounds, obtained from metal carbonyls and cyclic unsaturated hydrocarbons, are represented in a classic issue [11], Among these ligand-exchange syntheses, we mention here the transformations (3.119)—(3.121) ... 

Polymeric phosphin-Rh (XV) hydrogenizes several kinds of cyclic unsaturated hydrocarbon selectively, specifying the molecular size (114,153). 

Benzene ring The molecular structure of the cyclic, unsaturated, aromatic hydrocarbon benzene, C6H6 ... 

A special class of cyclic unsaturated hydrocarbons is known as the aromatic hydrocarbons. The simplest of these is benzene (C6H6), which has a planar ring structure, as shown in Fig. 22.11(a). In the localized electron model of the bonding in benzene, resonance structures of the type shown in Fig. 22.11(b) are used to account for the known equivalence of all the carbon-carbon bonds. But as we discussed in Section 14.5, the best description of the benzene molecule assumes that sp2 hybrid orbitals on each carbon are used to form the C—C and C—H a bonds, while the remaining 2p orbital on each carbon is used to form 77 molecular orbitals. The delocalization of these 1r electrons is usually indicated by a circle inside the ring [Fig. 22.11(c)]. 

Aromatic hydrocarbon one of a special class of cyclic unsaturated hydrocarbons, the simplest of which is benzene. (22.3) Arrhenius concept a concept postulating that acids produce hydrogen ions in aqueous solution, whereas bases produce hydroxide ions. (7.1)... 

Jenks et al. studied the effects of conjugation and aromaticity on the sulfoxide bond by means of ab initio computation <1996JOC1275>. They calculated S-O bond dissociation energies (BDEs) and found that, in a formally aromatic system such as thiophene sulfoxide, the SO BDE is decreased by as much as 25kcalmoP relative to the BDE of DMSO. Although the BDE of the formally antiaromatic thiirene sulfoxide increased by about 15 kcal moP the authors concluded, on the basis of calculated geometries and isodesmic reactions with pure hydrocarbons, that cyclic unsaturated sulfoxides are neither significantly aromatic nor antiaromatic. 

Define (a) isomer, (f ) diolefln, (c) cyclic hydrocarbon, (d) unsaturated hydrocarbon, (e) wet gas, (/) parafim base crude, (g) asphalt. 

Hunsdiecker reaction, 341 Hybridization, 17 Hybrid orbital number, 17, 18, 32 Hybrid, resonance, 24 Hydration of cyclohexane derivatives, 191 Hydrazine, 4 Hydride shift, 93 Hydroboration, 95 Hydroboration-oxidation, 258, 270 Hydrocarbons, cyclic, 162 unsaturated, 87 Hydrogenation of alkenes, 57 Hydrogen bond, 22 Hydroperoxides in ethers, 284 Hydroquinone, 430 Hydroxy acids, 344... 

The HF-pentavalent antimony halide reaction is not limited to the methane series but has been applied to longer-chain saturated and unsaturated halogenated hydrocarbons, cyclic olefins, and dienes, and certain of the silica organic derivatives. 

One of a special class of cyclic unsaturated hydrocarbons, the simplest of which is benzene... 

Oxidation of unsaturated and aromatic hydrocarbons in atmospheric and combustion processes results in formation of linear and cyclic unsaturated, oxygenated-hydrocarbon intermediates. The thermochemical parameters, A and Cpj T) for these... 

A special class of cyclic unsaturated hydrocarbons is known as the aromatic hydrocarbons. The simplest of these is benzene which has a planar... 

The size of the K-system chosen has important implication on the structural and functional aspects of metal binding. To explore the size effect calculations were performed on the cation-ir complexes of Li+ and Mg + with the Jt-face of linear and cyclic unsaturated hydrocarbons [45]. In the case of the acyclic Jt-systems, we started with the simplest system, e.g. ethylene followed by buta-1,3-diene, hexa-l,3,5-triene, and octa-1,3,5, 7-tetraene with 2, 3 and 4, conjugated jt units, respectively. These linear systems with two and more number of jt units can have various conformations wherein the jt units can have cis, trans or a combination of both cis and trans orientations. Similarly for cyclic systems cyclobutadiene, benzene, cyclooctateraene, naphthalene, anthracene, phenanthrene and naphthacene have been included. Thus a wide range of sizes for aromatic systems have been covered. 

The ring-opening polymerization of cyclic unsaturated hydrocarbons has been studied extensively(l-4), following the first report by Eleuterio(5 and subsequent discovery of homogeneous catalyst by Natta et al. (6). Typical catalyst is composed of a tungsten or a molybdenum compound and an organometallic compound. 

First of all, we restrict ourselves to C4 +2H4 +2 mono-cyclic, unsaturated hydrocarbon molecules with n = 1 to... 

Cyclic Hydrocarbons Cyclic hydrocarbons are saturated and unsaturated ring structures. These solvents have physical properties similar to those of aUphatics, although they are t5rpically more toxic. Examples of cychc hydrocarbons and their TLVs are cyclohexane (300 ppm) and turpentine (100 ppm). 

As was pointed out in Chapter 5, with reference to the conjugated ligand cyclooctatetraene, and as the structures of the cyClobutenyl nickel complex, 7.IS, and of the rhodium complex 7.18 show, it is not necessary for all the annular carbon atoms of a cyclic unsaturated hydrocarbon ligand to be involved in bonding to a metal. Further examples of this are shown in Figure 41, where in complexes derived from S-, 6- and 7-membered ring systems respectively, only 5 electrons are formally involved in the bonding in each case. 

Group VI. Concentrated sulphuric acid provides a simple test for the diflferentiation inter alia between (a) saturated paraffin and cyclic hydrocarbons and also simple aromatic hydrocarbons and (b) unsaturated hydrocarbons. 

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. 

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