Chains of carbon atoms

These consist of a chain of carbon atoms each carrying 0 to 3 hydrogen atoms except for the simplest molecule, methane CH. Each carbon atom is linked to four other atoms which can be either carbon or hydrogen. Their general formula is( 2 ... 

Unlike the forces between ions which are electrostatic and without direction, covalent bonds are directed in space. For a simple molecule or covalently bonded ion made up of typical elements the shape is nearly always decided by the number of bonding electron pairs and the number of lone pairs (pairs of electrons not involved in bonding) around the central metal atom, which arrange themselves so as to be as far apart as possible because of electrostatic repulsion between the electron pairs. Table 2.8 shows the essential shape assumed by simple molecules or ions with one central atom X. Carbon is able to form a great many covalently bonded compounds in which there are chains of carbon atoms linked by single covalent bonds. In each case where the carbon atoms are joined to four other atoms the essential orientation around each carbon atom is tetrahedral. 

With practice writing structural formulas for organic molecules soon becomes rou tine and can be simplified even more For example a chain of carbon atoms can be rep resented by drawing all of the C—C bonds while omitting individual carbons The result mg structural drawings can be simplified still more by stripping away the hydrogens... 

Find the longest continuous chain of carbon atoms and assign a basis name to the compound corresponding to the lUPAC name of the unbranched alkane having the same number of carbons... 

When the aldehyde group is directly attached to a carbon atom of a ring system, the suffix -carbaldehyde is added to the name of the ring system, e.g., 2-naphthalenecarbaldehyde. When the aldehyde group is separated from the ring by a chain of carbon atoms, the compound is named (1) as a derivative of the acyclic system or (2) by conjunctive nomenclature, for example, (1) (2-naphthyl)propionaldehyde or (2) 2-naphthalenepropionaldehyde. 

This is because rubber, like many polymers, is composed of long spaghetti-like chains of carbon atoms, all tangled together as we showed in Chapter 5. In the case of rubber, the chains are also lightly cross-linked, as shown in Fig. 5.10. There are covalent bonds along the carbon chain, and where there are occasional cross-links. These are very stiff, but they contribute very little to the overall modulus because when you load the structure it is the flabby Van der Waals bonds between the chains which stretch, and it is these which determine the modulus. 

Carbynes are a form of carbon with chains of carbon atoms formed from conjugated C(sp )=C(sp ) bonds (polyynes) ... 

Fig. I. Field emission dala from a mounted nanotube. An activated nanotube emits a higher current when heated by the laser than when the laser beam is bloeked (a). When aetivated by exposing the nanotube to oxygen while heating the tip, this behavior is reversed, and the emission current increases dramatically when the laser is blocked. The activated state can also be achieved by laser heating while maintaining a bias voltage of —75 V. Note that the scale of the two plots is different the activated current is always higher than the inactivated current. As discussed in the text, these dala led to the conclusion that the emitting feature is a chain of carbon atoms pulled from a single layer of the nanotube —an atomic wire.

Note that the backbone is a chain of carbon atoms which is very resistant to all forms of attack. 

Strategy First find the longest chain of carbon atoms. That tells you the suffix of the name, given in the far left column of Table 22.1. Then identify the prefix, or prefixes, by choosing the appropriate alkyl group from the right side of Table 22.1. Finally, number the carbon atoms as described above. 

Isobutane is a compound in a class of chemicals called alkanes. Alkanes are chains of carbon atoms where each carbon atom has as many hydrogen atoms attached as possible. This means that all of the bonds between carbon atoms are single bonds (no double bonds). Such a molecule is said to be saturated. 

Organic chemists have found a way to draw complex molecular structures in a very simple way, by not showing the C and H atoms explicitly. A line structure represents a chain of carbon atoms by a zigzag line, where each short line indicates a bond and the end of each line represents a carbon atom. Atoms other than C and H are shown by their symbols. Double bonds are represented by a double line and triple bonds by a triple line. Because carbon almost always forms four bonds in organic compounds, there is no need to show the C—FI bonds explicitly. We just fill in the correct number of hydrogen atoms mentally compare the line structure of 2-chlorobutane, QT3C1TC1CF12C]T3 (3a), with its structural form (3b). Line... 

A line structure (introduced in Section C) represents a chain of carbon atoms as a zigzag line. The end of each short line in the zigzag represents a carbon atom. Because carbon nearly always has a valence of 4 in organic compounds, we do not need to show the C—H bonds. We just fill in the correct number of hydrogen atoms mentally, as we see for methylbutane (6), isoprene (7), and propyne (8). As explained in Section 2.7, a benzene ring is represented by a circle inside a hexagon, and we need to remember that one hydrogen atom is attached to each carbon atom. 

Because the types of carbon-carbon bonds present in the molecule tend to dominate its properties, an aliphatic hydrocarbon is first classified as an alkane, alkene, or alkyne. Then the longest chain of carbon atoms is used to form the root of the name. Other hydrocarbon groups attached to the longest chain are named as side chains. 

A major MOCVD group is that of the alkyls. These are formed by reacting an aliphatic hydrocarbon or an alkyl halide with a metal.[" 1 These hydrocarbons are composed of chains of carbon atoms as shown below 1 1... 

Because of the atoms freedom to rotate about single bonds, a chain of carbon atoms can achieve various positions in space. On one extreme is the zig-zag extended chain and on the other is a coil. Such spatial structures become particularly important in determining properties of very long chained compounds known as polymers (Chapter 5). 

When naming the parent of the componnd, we are looking for the chain of carbon atoms that is going to be the root of onr name. Everything else in the compound is connected to that chain at a specific location, designated by numbers. So we need to know how to choose the parent carbon chain and how to number it correctly. 

Derivatives of aromatic hydrocarbons may have chains of carbon atoms substituted on the aromatic... 

Locate the longest continuous chain of carbon atoms this chain determines the parent name for the alkane. 

The methods referred to above have enabled a number of analogs of ascorbic acid to be isolated. These have been tested for antiscorbutic activity and the simple rule emerges that the five-atom lactone ring containing the enediolic system is essential for activity, and furthermore this lactone ring must be on the right side of the chain of carbon atoms when... 

The compounds of carbon are studied separately in organic chemistry. There are well over 2 million such compounds, because of the ability of carbon to form covalently bonded chains of carbon atoms. However, the study of organic chemistry does not include the chemistry of oxides of carbon or metal carbonates, e.g. calcium carbonate. 

Of these the third one is excluded because it is unfavourable and all the three substituents in it are in the skew position. If the chain of carbon atoms is longer, the number of conformations also increases sharply and according to Bremster the calculations of such compounds also becomes complicated and requires the building up of the dimensional models, a discussion of this is beyond the scope of the present text. 

There are a number of structurally distinct classes of amphipathic molecules, which have various kinds of structures. The simplest amphipathic molecules have a straight chain of carbon atoms, usually 8-18 in number, to which is attached a polar group that may be anionic, cationic, zwitterionic or nonionic. 

Data for the specific rate coefficients for abstraction from CH bonds have been derived from experiments with hydrocarbons with different distributions of primary, secondary, and tertiary CH bonds. A primary CH bond is one on a carbon that is only connected to one other carbon, that is, the end carbon in a chain or a branch of a chain of carbon atoms. A secondary CH bond is one on a carbon atom connected to two others, and a tertiary CH bond is on a carbon atom that is... 

Alkanes (also called normal paraffins or n-paraffins). These constituents are characterized by branched or unbranched chains of carbon atoms with attached hydrogen atoms, and contain no carbon-carbon double bonds (they are saturated). Examples of alkanes are pentane (C5H12) and heptane (C7H16). 

---