Cyclic Compounds
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Cyclic Compounds

Sometimes the carbon atoms in an alkane will form a complete ring. Such compounds are called cyclic compounds or ring compounds. When this happens, the prefix cyclo- is added to the name.

Thus, the alkane with the six-carbon ring shown here (also shown in example 18 in your workbook) is called cyclohexane.
   CH2 - CH2
   /       \
  CH2       CH2
   \       /
    CH2 - CH2

        cyclohexane

Cyclohexane model.[61mod14.JPG (8753 bytes)]
If groups of atoms are attached to the ring, then the appropriate prefixes are added to the name as shown in the following examples.
Note that it is not necessary to use the number prefix when only one group is attached to the ring. Thus, this compound is called methylcyclohexane.
     CH2 - CH2
    /       \
   CH2       CH-CH3
    \       /
     CH2 - CH2

     methylcyclohexane
However, when two groups are attached, it is necessary to show where they are attached with respect to one another. So, this compound is 1,2-dimethylcyclohexane.
     CH2 - CH2
    /       \
   CH2       CH-CH3
    \       /
     CH2 - CH-CH3

   1,2-dimethylcyclohexane

 

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