Compound Carbon Chemistry

The creation of carbon, like that of the other elements, is part of the history of the universe. All but the lightest of the natural elements were created in the cores of stars at extreme temperatures. In this process, called nucleosynthesis, protons are smashed together to form nuclei with more and more protons (heavier and heavier elements). Carbon was formed by collisions of three helium nuclei, each 

Some elements have several different forms. In the case of carbon, charcoal was the only recognized form until early in the nineteenth century. The name carbon actually comes from the Eatin word carbo, meaning charcoal. In 1812, Sir Humphry Davy used sunlight to set a diamond on fire. This demonstration, combined with his scientific explanation, proved that diamonds were made of pure carbon. Around the same time, Davy also showed that coal was another form of carbon. Graphite, which is the lead in pencils, is 

Although humans have used, recognized, and studied carbon for centuries, modern scientists are still learning new things about this element. In 1985, a group of researchers at Rice University in Houston, Texas, discovered still another form of carbon, which was named fullerene. Fullerene consists of multiple carbon atoms joined together in spherical or tubelike shapes. Fullerenes are discussed in more detail in Chapter 9. 

The physical properties of a substance are those attributes that can be observed without any chemical changes. Examples of physical 

Chemical series A group of elements that has certain properties in common Nonmetal 

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One of the cornerstones of the chemistry of carbon compounds (organic chemistry) is Kekule s concept, proposed in 1858, of the tetra-valence of carbon. It was independently proposed in the same year by Couper who, however, got little recognition (vide infra). Kekule realized that carbon can bind at the same time to not more than four other atoms or groups. It can, however, at the same time use one or more of its valences to form bonds to another carbon atom. In this way carbon can form chains or rings, as well as multiple-bonded compounds. 

By the mid-1800s, the new science of chemistry was developing rapidly and chemists had begun to probe the forces holding compounds together. In 1858, August Kekule and Archibald Couper independently proposed that, in all its compounds, carbon is tetravalent—it always forms four bonds when it joins other elements to form stable compounds. Furthermore, said Kekule, carbon atoms can bond to one another to form extended chains of linked atoms. 

Although Kekule and Couper were correct in describing the tetravalent nature of carbon, chemistry was still viewed in a two-dimensional way until 1874. In that year, Jacobus van t Hoff and Joseph Le Bel added a third dimension to our ideas about organic compounds when they proposed that the four bonds of carbon are not oriented randomly but have specific spatial directions. Van t Hoff went even further and suggested that the four atoms to... 

Where do we find the enormous quantities of carbon and carbon compounds needed to feed this giant industry Let s begin our study of carbon chemistry by taking a look at the chief sources of carbon and carbon compounds. 

The seminal studies on these complex compounds were conducted by Alfred Werner in an intensive period of work at the turn of the century. A typical example of the problems that Werner addressed lies in the various compounds which can be obtained containing cobalt, ammonia and chlorine. Stable and chemically distinct materials with formulations Co(NH3) Cl3 (n = 4,5 or 6) can be isolated. The concepts of valency and three-dimensional structure in carbon chemistry were being developed at that time, but it was apparent that the same rules could not apply to... 

Despite the increasing interest in understanding the phenomena of bonding in silicon compounds, there are, until now, no well established and commonly accepted theories. Silicon compounds are mainly discussed in terms of carbon chemistry. Thus, specific properties of silicon compounds are usually compared with those of the corresponding carbon homologues. In this report some important features of silicon compounds are developed by means of ab initio calculations. From this a set of basic rules will be presented by which more complex phenomena can be explained in turn. 

In the right part of the Table hydrides having covalent characteristics are observed. For the elements of the last groups several covalent hydrogen compounds are known numerous compounds are given by B, C, Si, Ge, N, P, O, S, Se. In the usual ambient conditions, as it is well-known, the carbon chemistry is especially rich of hydrides (that is of several series of hydrocarbons). In this class of compounds more or less complex molecules and structures are found the catenation (chainforming) tendency is a characteristic shown by several elements in this portion of the Periodic Table. 

Hexacoordinate phosphorus compounds are also considered as transition states in nucleophilic diplacements of phosphoranes in a manner similar to an 2 displacement in carbon chemistry (see Scheme 38) (72MI11704, 73AG(E)9l>. 

IV. RADICAL IONS OF >C=C< CONTAINING COMPOUNDS A. Chemistry of Radical Cations Derived from Carbon-Carbon Double Bonds... 

All organisms are composed of compounds which contain carbon. Why do you think carbon chemistry is often called organic chemistry ... 

Compounds containing a skeleton of cumulated P-P bonds have been rare until recently, as they are in general highly reactive. This means that they can easily be oxidized and have a strong tendency to disproportionate. Nevertheless, considerable progress has been achieved in this field lately. Thereby a significant analogy of phosphorus- to carbon-chemistry became apparent with respect to structural features. 

What is interesting, however, is some of the chemistry that is not present. For example, the petrochemical industry does not have a basic feedstock in the five-carbon area and thus we see few products derived from or based on five-carbon chemistry. Optical active compounds are also missing from the petrochemical-derived product list. For example, lactic acid is now made exclusively from glucose, with the reason being that the fermentation route provides stereochemical purity that is difficult to achieve from petrochemical building blocks. 

The structure of silyl cyanides was a matter of dispute for many years. Emeleus, Maddock and Reid (1941) prepared silyl cyanide by the reaction of SiH3I with solid AgCN. The normal cyanide structure was written for this product without comment. However, on the basis of analogy with carbon chemistry, MacDiarmid (1956) suggested that the compound should be formulated as an isocyanide, H3SiNC. The problem Was finally resolved by careful infrared and microwave spectral studies which showed that the normal cyanide, H3SiCN, is correct (Linton and Nixon, 1958 a Mutter and Bracken, 1960 Sheridan and Turner, 1960). 

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