Organic chemistry hydrocarbon derivatives

Silicon and carbon command dominant positions in inorganic chemistry (silicates) and organic chemistry (hydrocarbons and their derivatives), respectively. Although they have similar valence electronic configurations, [He]2s22p2 for C and [Ne]3s23p2 for Si, their properties are not similar. The reasons for the difference between the chemistry of the two elements are elaborated below. 

In organic chemistry, hydrocarbons are considered parent compounds, while other organic compounds are considered derivatives. This analogy... 

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... 

The ability of C to catenate (i.e. to form bonds to itself in compounds) is nowhere better illustrated than in the compounds it forms with H. Hydrocarbons occur in great variety in petroleum deposits and elsewhere, and form various homologous series in which the C atoms are linked into chains, branched chains and rings. The study of these compounds and their derivatives forms the subject of organic chemistry and is fully discussed in the many textbooks and treatises on that subject. The matter is further considered on p. 374 in relation to the much smaller ability of other Group 14 elements to form such catenated compounds. Methane, CH4, is the archetype of tetrahedral coordination in molecular compounds some of its properties are listed in Table 8.4 where they are compared with those of the... 

Classical organic chemistry provides a wide variety of potential analytes for electron ionization, the only limitation being that the analyte should be accessible to evaporation or sublimation without significant thermal decomposition. These requirements are usually met by saturated and unsaturated aliphatic and aromatic hydrocarbons and their derivatives such as halides, ethers, acids, esters, amines, amides etc. Heterocycles generally yield useful El spectra, and flavones, steroids, terpenes and comparable compounds can successfully be analyzed by El, too. Therefore, El represents the standard method for such kind of samples. 

INORGANIC CHEMISTRY. A major branch or chemistry that is generally considered to embrace all substances except hydrocarbons and their derivatives, or substances that are not compounds of carbon, with the exception of carbon oxides and carbon disulfide. The chemical compounds, which are based upon chains or rings of carbon atoms, which are termed organic compounds, are studied under the separate heading of organic chemistry. See also Organic Chemistry. 

Derivatives of polycyclic hydrocarbons have played a central role in the development of physical organic chemistry 29°). Polycyclic substrates have been found to be ideal models for numerous quantitative investigatious since their conformations are generally rigid and fixed and since they provide a large variation in structural types. Recent, comprehensive reviews of bridgehead reactivity are available 187> 291f... 

Early work in the area of physical organic chemistry revealed that the bridgehead positions of many polycyclic hydrocarbons are unusually inert to solvolysis and to nucleophilic attack 187>. It is now realized that the solvolytic reactivities of bridgehead derivatives of a variety of polycyclic hydrocarbons vary widely. This is illustrated below for the adamantane family. The reactivities range from 3-homoadamantyl (93), the reactivity of which is nearly the same as that found for typical tertiary acyclic analogues (e.g. f-butyl), to 7-methyl-3-noradamantyl (94) 36 9S>10Si 187 ... 

The nomenclature system outlined in this report follows many customary terpene practices but also conforms to established nomenclature rules and practices. The resulting terpene-like names are much simpler than the strict systematic names formed according to IUPAC rules. Replacement of the currently used common terpene names by the recommended ter-pene-like pseudosystematic names will facilitate ready recognition of the terpene hydrocarbon structures and will aid in integrating terpene chemistry with the entire field of organic chemistry. Extension of the hydrocarbon rules to the naming of functional derivatives will simplify and unify nomenclature within the terpene field. 

Relationships of molecular topology to chemical reactivity of polynuclear benzenoid hydrocarbons are of interest for both theoreticians and experimentalists. Reactivity indices, derived from topological approaches to the chemistry of benzenoid hydrocarbons, have proved useful in such varied fields as mechanistic organic chemistry, biochemistry, carbon science, and environmental science. It is not the aim of this review, however, to give a comprehensive account of reactivity indices of benzenoid hydrocarbons. Instead, the main emphasis is placed on the underlying basic principles of the relationship between topology and reactivity of benzenoid hydrocarbons. 

Nowadays it is very difficult to pinpoint in the classical literatures in organic chemistry the credit of attributing the relative stability of unsaturated hydrocarbon molecules to K(G) [2, 3], On the other hand, long before these quantum-chemical theories were introduced Robinson proposed using a circle inside each benzene ring of an aromatic hydrocarbon molecule to represent the six mobile electrons and also the derived aromatic stability [4], However, his symbol does not reflect any difference in the stability between I and II as,... 

Aluminum chloride is used in the petroleum industries and various aspects of organic chemistry technology. For example, aluminum chloride is a catalyst in the alkylation of paraffins and aromatic hydrocarbons by olefins and also in the formation of complex ketones, aldehydes, and carboxylic acid derivatives. 

Fluorocarbons. Fluorocarbons represent a large class of compounds, which could in principle encompass the known variety of hydrocarbon derivatives. For the extensive literature in this area a number of comprehensive works can be consulted.The focus of much fluorocarbon chemistry is technically organic chemistry and will not be covered here. The more inorganic aspects of carbon-fluorine chemistry such as the chemistry of simple fluorocarbons, oxyfluorides, and their derivatives will be covered. Trends in reactivity can often be generalized from small molecules to compounds with longer fluoroalkyl chains. 

Cyclic compounds played an important role in organic chemistry from its very beginning. Both rings with carbon-only skeletons (cyclic hydrocarbons and their derivatives) and with heteroatom skeletons (an endless diversity of heterocycles) have been known for a long time. The discovery of the cyclic structure of benzene is a landmark in the history of chemistry, and it has been followed by a rapid progress in this branch of science, even in the nineteenth century, when elemental analysis and the chemist s intuition and imagination were the most important research tools. 

Part of the interest in fluorocarbon systems lies in a comparison of the chemistry, and particularly reaction mechanisms, of fluorocarbon derivatives with those of the corresponding hydrocarbon compounds. Indeed, such comparisons pose quite a strenuous test on our theories of organic chemistry. As will be seen, our understanding of the influence of carbon-fluorine bonds on reaction mechanisms has made considerable progress. Nevertheless, it must be emphasised that fluorocarbon derivatives present much more complicated systems than their corresponding hydrocarbon compounds because, in addition to effects arising from different electronegativities, the effect of the lone pairs of electrons of fluorine that are not involved in o-bonds must be taken into consideration. Furthermore, the relative importance of these effects seems to be very dependent on the centre to which the fluorine is attached. 

Because organic chemistry is such a vast subject, we can provide only a brief introduction to it in this book. We will begin with the simplest class of organic compounds, the hydrocarbons, and then show how most other organic compounds can be considered to be derivatives of hydrocarbons. 

The vast majority of organic molecules contain elements in addition to carbon and hydrogen. However, most of these substances can be viewed as hydrocarbon derivatives, molecules that are fundamentally hydrocarbons but that have additional atoms or groups of atoms called functional groups. The common functional groups are listed in Table 22.4. Because each functional group exhibits characteristic chemistry, we will consider the groups separately. 

Of all of the elements of the Periodic Table, only neighboring carbon and boron share the properties of self-bonding (catenation) and the support of electron-delocalized structures based upon these catenated frameworks. Carbon catenation, of course, leads to the immense field of organic chemistry. Boron catenation provides the nido-, arachno-, and /i p/io-boranes, which may be considered as the borane equivalents of aliphatic hydrocarbons, and the discrete families of c/oso-borane derivatives which bear a for nal resemblance to the aromatic hydrocarbons, heterocycles, and metallocenes. Aside from these analogies, boron and carbon chemistries are also important to each other through their extravagant ability to mix m ways not available to other element-pairs. Thus, the conflux of boron and carbon chemistries effectively provides an element-pair for exploitation in a variety of novel ways. 

Metallaboranes mirror the metal hydrocarbyl complexes of organometallic chemistry and offer the promise of a similar rich chemistry.1 Indeed there are a number of strictly isoelectronic borane and hydrocarbon complexes in which a C atom is formally replaced with a B or BH moiety.2 Comparison of the structure and properties of these compound pairs highlights interesting similarities and differences between the organic and inorganic derivatives.3... 

Most organic compounds that show absorption in the visible or in the near-UV region have a linear or cyclic n system as the chromophoric system. Therefore, the results of the previous sections may be used and extended to discuss light absorption of all those compounds that can be derived from linear and cyclic hydrocarbons by including the influence of substituents in an appropriate way. (Cf. Michl, 1984.) A complete theory of substituent effects comprises all areas of organic chemistry. Here, only the fundamental concepts of the influence of inductive and mesomeric substituents will be considered. In order to simplify the discussion, substituent effects will be called inductive if in the HMO model they can be represented by a variation of the Coulomb integral of the substituted n center p. If they are due to an extension of the n system they will be called mesomeric. 

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