Ring compounds cyclo prefix

The prefix cyclo- appears before the root of the name in ring compounds, except for those involving the benzene ring (Problem 9.9). The benzene compounds form a special category of compounds referred to as aromatic compounds. The opposite of aromatic is aliphatic. Further modifications of the system, such as those when elements other than carbon and hydrogen are involved, will be noted when functional groups are discussed. 

The procedure used to name a cycloalkane by the IUPAC method is very similar to that used for alkanes. Here, the root designates the number of carbons in the ring and the prefix cyclo- is attached to indicate that the compound contains a ring. The rules for numbering the ring carbons are as follows ... 

Most of the chains mentioned with three or more carbons can be bent around and formed into a ring. Such ring compounds are named similarly to the straight chains, except that their name starts with the prefix cyclo. Cyclopropane and cyclohexane are shown in Figure 1.11. 

One of the reasons that such a variety of organic compounds exists is that carbon atoms can form ring structures. An organic compound that contains a hydrocarbon ring is called a cyclic hydrocarbon. To indicate that a hydrocarbon has a ring structure, the prefix cyclo- is used with the hydrocarbon name. Thus, cyclic hydrocarbons that contain only single bonds are called cycloalkanes. 

Alkanes may also form ring systems to make compounds called cycloalkanes. The naming of these compounds is very similar to the branched kanes, except the cyclo- prefix is used on the parent name. In the condensed structurad formula, the ring is often drawn as lines where the intersection of two straight lines indicates a carbon atom, and the hydrogen atoms aren t shown at all. Figure 14-6 shows both the expanded and condensed form of 1,3-dimethyl cyclohexane. 

Step 1 Find tbe root Identify the longest chain or ring in the hydrocarbon. If the hydrocarbon is an alkene or an alkyne, make sure that you include any multiple bonds in the main chain. Remember that the chain does not have to be in a straight line. Count the number of carbon atoms in the main chain to obtain the root. If it is a cyclic compound, add the prefix -cyclo- before the root. 

If there is a ring, it is usually taken as the main chain. Follow the same rules to name cyclic compounds that have branches attached. Include the prefix -cyclo-afterthe names and position numbers of the branches, directly before the root for example, 2-methyl-1-cyclohexene. 

Example 1 You can still use the general formula prefix + root + suffix. In Figure 13.27, there are only single carbon-carbon bonds. There are also five corners (carbon atoms) in the ring, which is the main chain. Since there are no branches, the name of this compound is cyclopentane. Notice the addition of cyclo- to indicate the ring structure. 

Cycloalkanes are a family of organic molecules having C—C single bonds in a ring structure. They are named by adding the prefix cyclo- to the name of the alkane parent compound. 

These are alkanes in which the carbon atoms form a ring. The prefix cyclo- is used in the names of these compounds to indicate their cyclic nature. 

Cyclic alkenes are known compounds. As with cyclic alkanes, the parent name for cyclic alkenes is based on the number of carbon atoms in the ring derived from the analogous linear alkene, but the prefix cyclo is added to the name. The six-carbon cyclic molecule that contains a C=C unit is called cyclohexene (4). Substituents are named in the usual manner, and one carbon of the C=C unit must be Cl. The choice of which C=C carbon becomes Cl is dictated by giving the substituents the lowest number. Compound 5 is a cycloheptene, but the substituents can be numbered 6-ethyl-3,6-dimethyl- or 4-ethyl-4,7-di-methyl. The smaller numbers dictates the priority, which also give the ethyl group the lower number, and 5 is 4-ethyl-4,7-dimethylcycloheptene. Note that the 1-heptene is unnecessary in the name... 

Cyclic compounds that have a ring of carbon atoms, which are not aromatic, are named using the prefix cyclo. For example, cyclobutane is a cyclic alkane with four carbon atoms. The atoms in the ring are numbered so that the smallest numbers indicate the position of substituents. 

If the C atoms in an alkane are bonded in a row with a formula of the form CH3(CH2)mCH3, the compound, called an unbranched alkane, is named according to the number of C atoms present. All are named with a stem name and the suffix -ane. A cyclic (ring) alkane has the general formula (CH2)m and is designated by the prefix cyclo-. 

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