Nomenclature
Alkanes
In Chemistry carbon chains are numbered using the following terms
The prefix denotes the number of carbons while the suffix denotes the type of carbons
# of Carbons
1
2
3
4
5
6
7
8
9
10
Type of Carbons
Single Bonded
Double Bonded
Triple Bonded
Prefix
MethEthPropButPentHexHeptOctNonDec-
When alkanes branch,
1) find the longest continuous chain and use
that root word (followed by -ane for alkanes)
Suffix
-ane
-ene
-yne
7 carbons
(hept-)
Examples
Butane
Propene
Ethyne
2) number the chain so the the substituents
have the lowest possible numbers
1
H
H
H3C
3) with multiple substituents, list alphabetically
with their position along the longest chain
(use di, tri, and tetra for identical branches)
2
CH3
3
4
5
6
7
2,3-dimethylheptane
Alkenes/Alkynes
Most of the rules for naming alkene are the same as alkanes with one key difference
The root word is based on the longest carbon chain WITH THE ALKENE.
Not oct-,
1
2
3
4
5
6
7
8
But sept-
1
7
Note: The alkene was given the lower number,
analogous to the substituents with alkanes.
2
6
5
4
3
5-methyl-3-propylheptene
Remember: List the
substituents in
alphabetical order
Examples
Note: When the molecule has
both an alkene and an alkyne
the alkene will get priority
Cl
5-chlorohex-2-yne
hex-1-en-5-yne
Br
Halogens
Br
Cl
Molecules with halogens (and later, other groups) use the
same numbering system as alkanes and alkenes.
The halogen substituents are named fluoro, chloro, bromo, and iodo.
Cl
Br
Br
F
2-bromo-3-fluoro-4-methylheptane
I
2,3,5-tribromo-6,6-dichloro-4-propyloctane
3-(iodomethyl)pentane
Note: Even though there are two possible
longest carbon chains, the parent one is the
one with more substituents
Remember: The side chains are listed
alphabetically by the prefix(bromo-,
chloro-, propyl-)