How do you name alkenes with alcohols?
The basic rules for naming alkenes are the same as those for the nomenclature of alkanes, except that we change the suffix to –ene.
Find the longest continuous chain of carbon atoms that contains the
#"C=C"#double bond. If you have two ties for longest continuous chain and both chains contain a #"C=C"#double bond, then choose the chain with more substituents.
Give the lowest possible number to the
Add substituents and their positions to the name of the alkene as prefixes. Of course, remember to give them the lowest numbers possible and to write them in alphabetical order.
Identify stereoisomers. You can use the cis/trans notation when there is a hydrogen atom on each of the alkene carbons, but it is always safer to use the Cahn-Ingold-Prélog
#E//Z#notation. #E#(entgegen) means the higher priority groups are on opposite sides of the double bond. #Z#(zusammen) means the higher priority groups are on the same side of the double bond.
Functional Groups Have Higher Priority Than Double Bonds
The only groups with lower priority than
The parent chain must contain the alcohol group and go through as many
Let’s apply these rules to the naming of geraniol, a primary component of rose oil that the perfumes industry uses.
Its structure is
We start at the carbon bearing the
We now have an octa-2,6-dien-1-ol (It is acceptable to call this a 2,6-octadien-1-ol, but it is now the preferred practice to put the locating numbers as close as possible to the groups they locate).
In addition, there are methyl groups at
Now we indicate stereochemistry.
We cannot use cis/trans for the
The two higher-priority groups are the
Since they are on opposite sides of the double bond, the configuration is
The full name for geraniol is (2