Cyclic Compounds 2 - Cycloalkenes

This section deals with cyclic compounds that have double bonds.
This makes the numbering easier since the numbering MUST start with 1 and 2 ACROSS the double bond.
Try numbering opposite to the examples provided to check.

Example 1

cyclohexene
The -ene in the name indicates the double bond.
No numbering required, since no other atoms, other than the hydrogens are present.
The molecular formula is: C6H10
Draw the molecule out to count the individual atoms.
Example 2

4-chlorocyclohexene
The numbering MUST start and cover the double bond.
Hence the chlorine is at carbon 4.
The molecular formula is: C6H9Cl

Example 3

3-bromo-5-chlorocyclopentene
After numbering the double bond, the bromine was given preference over the chlorine due to alphebetical reasons. (either could be at 3, if you numbered the double bond the other way.)

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