Here is an example of an alkene.
Notice the carbon chain in RED, and that there is a DOUBLE BOND between two of the carbons.
We say that the DOUBLE BOND is at carbon 2.
TWO chlorine atoms are added in as well.
5,5-dichloro-pent-2-ene
How do you name ALKENE compounds?
The method is similar as in naming alkanes, but you must indicate the POSITION of the DOUBLE BOND.
Step 1
Then the road is 5 carbons long.
Now 5 carbons = pent
Notice that the numbering starts closer to where the double is, and not from where the chlorine is located.
Step 2
The DOUBLE BOND is at carbon number 2.
Hence we say 2-ene.
We combine pent and 2-ene.
Hence the road name is pent-2-ene.
Step 3
Now the chlorine atoms are found at carbon 5 and 5
We call it 5,5-dichloro
(di means 2 atoms)
We combine all the words into one big word!
Hence the name is:
5,5-dichloro-pent-2-ene
4-bromo-1-choro-but-1-ene
"Main road" is but-1-ene
Notice that the numbering starts from the side closer to the double bond.
There is a 4-bromo and a 1-chloro.
These are written in alphabetical order.