Naming Organic Molecules
Naming Hydrocarbons:
Hydrocarbons are molecules made from carbon and hydrogen.
H
H
C
H
H
H
Methane
H
H
H
C
C
H
H
Ethane
H
H
H
C
C
C
H
H
H
H
Propane
H
H
H
H
H
H
C
C
C
C
H
H
H
H
Butane
H
Naming Hydrocarbons
Number of Carbons
Name
1
Methane
2
Ethane
3
Propane
4
Butane
5
Pentane
6
Hexane
7
Heptane
8
Octane
9
Nonane
10
Decane
Naming hydrocarbons: 5 Rules
1. Identify the longest continuous carbon chain
(the parent chain), which may or may not be
shown in a straight line, and name the chain.
H3C
CH2
CH2
CH
CH3
pentane
CH3
CH3
CH
CH2
CH3
CH2
CH2
CH3
hexane
2. Number the carbon atoms in the parent chain from
the end of the nearest substituent
(alkyl group).
1
2
H3C
3
CH2
5
4
4
CH2
3
5
CH
CH3
2
1
CH3
CH3
3
4
CH
CH2
4
2
1
3
CH2
5
CH3
6
6
5
CH2
2
CH3
1
3. If only one alkyl group is present, name and locate it
(by number), and attach the number and name to
that of the parent chain.
H3C
CH2
5
4
CH2
3
CH
CH3
2
1
CH3
2-methylpentane
one word
CH3
2
1
3
4
CH
CH2
CH2
CH3
5
CH2
6
CH3
hyphen
3-methylhexane
Alkyl group naming – Change “ane” to “yl” when the
substituent is an alkyl group.
Number of Carbons
Name
Name
1
Methane
Methyl
2
Ethane
Ethyl
3
Propane
Propyl
4
Butane
Butyl
5
Pentane
Pentyl
6
Hexane
Hexyl
7
Heptane
Heptyl
8
Octane
Octyl
9
Nonane
Nonyl
10
Decane
Decyl
4. If two or more of the same kind of alkyl group are
present in a molecule, indicate the number with a
Greek numerical prefix (di, tri, tetra, penta…). In
addition, a number specifying the location of each
identical group must be included. These position
numbers, separated by commas, precede the
numerical prefix. Numbers are separated from by
hyphens.
1
H3C
2
CH
3
CH2
CH3
4
5
CH
CH3
2,4-dimethylpentane
CH3
CH3
1
H3C
2
CH2
3
4
C
3,3-dimethylpentane
CH3
5
CH2
CH3
5. When two kinds of alkyl groups are present on the
same carbon chain, number each group separately, and
list the names of the alkyl groups in alphabetical order.
5
H3C
4
CH2
3
CH
2
CH2
CH3
di, tri… doesn’t count
for alphabetizing…
CH3
3-ethyl-2-methylpentane
CH3
1
H3C
3-ethyl-4,5-dipropyloctane
CH
1
2
CH2
3
CH
4
CH
5
CH
CH2
CH2
CH2
CH3
CH2
CH2
CH3
CH3
6
CH2
7
CH2
8
CH3
Example
1
2
H3C
3
CH
8
4
CH2
7
CH3
6
6
5
CH2
5
CH
CH2
4
CH2
7-methyl
M
3
8
CH
2
CH3
2-methyl
CH3
2,7-dimethyl
7
4-ethyl
E
4-ethyl-2,7-dimethyloctane
CH3
1
Beyond Hydrocarbons:
Other Functional Groups
Functional Groups
A.
Multiple Bonds
Single
Bond
H
H
H
C
C
H
Ethane
H
Double
Bond
H
H
C
H
Triple
Bond
H
C
H
C
C
H
Ethene
“Ethylene”
Ethyne
“Acetylene”
H
B. Halides
H
H
H
C
C
H
H
H
F
H
C
C
H
H
Cl
Ethyl Chloride
Ethyl Fluoride
H
H
H
H
C
C
H
H
Ethyl Bromide
Br
H
H
H
C
C
H
H
Ethyl Iodide
I
C. Alcohols and Ethers
H
H
H
C
C
H
H
OH
H
H
H
C
C
H
H
O
Ethyl Alcohol
Diethyl Ether
“Ethanol”
“Ether”
H
H
C
C
H
H
H
D. Aldehydes and Ketones
H
H
O
C
C
H
Ethanal
“Acetaldehyde”
H
H
H
O
H
C
C
C
H
Dimethyl Ketone
“Acetone”
H
H
E. Carboxylic Acids and Esters
H
H
O
C
C
H
Ethanoic Acid
“Acetic Acid”
OH
H
H
O
C
C
O
H
Ethyl Acetate
H
H
C
C
H
H
H
F. Amines
H
H
H
C
C
H
H
H
NH2
H
H
H
H
H
C
C
N
C
C
H
H
H
H
Diethyl Amine
H
Ethyl Amine
H
H
C
H
C
H
H
H
H
H
H
C
C
N
C
C
H
H
H
H
Triethyl Amine
H
H
G. Amides
H
H
O
C
C
H
“Acetamide”
NH2
H. Thiols and Disulfides
H
H
H
C
C
H
H
Ethanethiol
SH
H
H
H
C
C
H
H
S
S
Diethyl disulfide
H
H
C
C
H
H
H
III.
O
R-Groups are “Generics”
R
Cl
R
R
R
C
OH
Halide
O
OH
O
Carboxylic Acid
R'
Alcohol
R
C
R
Ether
O
N
R'
R"
Ester
Amine
R'
O
R
C
H
O
R
C
R'
O
Aldehyde
R
Ketone
R
C
NH2
R
SH
S
S
Amide
Thiol
R'
Disulfide