Carbon atom in organic compounds

For convenience, the carbon atoms in organic compounds are given position numbers. In straight-chain hydrocarbons, the numbering can begin at either end. It makes no difference. In branched hydrocarbons, the numbering begins at the end closest to the branch. 

You learned in Chapter 9 that carbon atoms in organic compounds can be connected by single, double, or triple bonds. A hydrocarbon that has one or more double or triple bonds between carbons is called an unsaturated hydrocarbon. Molecules with single, double, and triple bonds are compared in Figure 18.4. 

Figure 9.1. Carbon atoms in organic compounds bond with each other in straight chains, branched chains, and rings. In addition to single bonds, carbon atoms may be joined by double and even tr bonds. Because of this remarkable bonding diversity, there are literally millions of known organic compounds.

A. Fiirst, E. Pretsch, W. Robien, A comprehensive parameter set for the prediction of the 3c NMR chemical shifts of sp-hybridized carbon atoms in organic compounds, Anal. Chim. Acta 1990, 233, 213. 

The normal valency of carbon atoms in organic compounds is 4, so the valencies of the nodes in the hydrogen-suppressed structural graphs of simple alkanes are limited to the values of... 

Covalent — refers to a chemical bond in which there is an equal/even sharing of bonding electron pairs between atoms. This is typical of the bonding between carbon atoms and between carbon and hydrogen atoms in organic compounds. 

List the pairs of organic functional groups that can be isomeric with each other if the numbers of carbon atoms in their compounds are the same. 

A classic method14 for examining the thermochemical regularity of an organic homologous series is plotting the standard molar enthalpies of formation versus the number of carbon atoms in the compounds. The linear relationship may be expressed as equation 1 where all the enthalpies of formation are in either the gaseous or a condensed phase, a is the slope, ft is the y-intercept and nc is the number of carbon atoms in the compound. 

Different organic functional groups (i.e., methyl, methylene, phenyl, and the hydrogen atoms adjacent to the carbonyl carbon in aldehydes and organic add groups) absorb at different frequencies and thus can be easily identified. Similarly, different 13C environments result in different absorption characteristics. For instance, carbon atoms in aromatic compounds absorb different frequencies than do those in carbonyl groups. 

A major conclusion from analyses of carbon isotopes in organic compounds in chondrites is that 513C values decrease as the number of carbon atoms in the molecule... 

The single bonds between carbon and hydrogen atoms in organic compounds are not highly reactive. However, these compounds do participate in a variety of chemical reactions, one of which is called a substitution reaction. A substitution reaction is a reaction in which one or more atoms replace another atom or group of atoms in a molecule. Another type of reaction involving organic compounds is an addition reaction in which an atom or molecule is added to an unsaturated molecule and increases the saturation of the molecule. 

PREFIXES The prefix of the name for an organic compound describes how the carbon atoms in the compound are arranged. Organic molecules that have names with the prefix cyc/o- contain a ring of carbon atoms. For example, cyclopentane contains five carbon atoms all joined by single bonds in a ring. 

The isotopic distributions of several elements commonly found in organic compounds are shown in Table 13.2. From the isotopic distributions, we see why the M -b 1 peak can be used to determine the number of carbon atoms in a compound It is because the contributions to the M + 1 peak by isotopes of H, O, and the halogens are very small or nonexistent. This formula does not work as well in predicting the number of carbon atoms in a nitrogen-containing compound because the natural abundance of is relatively high. 

Isomerism increases the number of organic compounds. The more carbon atoms in a compound, the more ways of arranging the atoms and the larger number of isomers. 

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