Download Functional groups Priorities

Functional groups Priorities
By
Dr. Seham ALTERARY
Functional Group Precedence in IUPAC nomenclature
When two or more functional groups are present in a molecule, that group
highest in the table is used as the parent (suffix) in the IUPAC name
and all others are cited as substituents (prefixes).
Function
Group Name
Formula
Prefix
Priority Order
Suffix
Group Type
Group A
Functionl
groups
Named by
Prefix
or
Suffix
1-
Carboxyl
-COOH
carboxy-
-oic acid
2-
Ester
-COOR
R-oxycarbonyl-
-R-oate
3-
Aldehyde
-CHO
Formyl-
-al
4-
Ketone
>C=O
oxo-
-one
5-
Alcohol
-OH
6-
Amines
-NH2
hydroxyAmino-
-ol
-amine
Function
Group Name
Formula
Prefix
Suffix
Priority Order
7-
Alkene
C
8-
Alkyne
C
Substituents
Formula
Prefix
Suffix
9-
Alkyl
R-
Alkyl-
----------
10-
Alkoxy
RO-
Alkoxy-
----------
11-
Halogen
FClBrI-
FluoroChloroBromoIodo-
C
C
---
-ene
---
-yne
Group Type
Group B
Function
al groups
Named by
Suffix
only
Group
Type
Group C
Function
al groups
Named by
Prefix
only
list of important functional groups arranged in decreasing priority
order.
Carboxylic acids
R-COOH
Highest Priority
Priority Order
Least Priority
Acid anhydride
Ester
Acid halide
Amide
Aldehyde
R-COOCO-R
R-COO-R’
R-CO-X
R-CO-NH-R’
R-CHO
Ketones
Alcohols
Amines
Ethers
Alkene
Alkyne
R-CO-R’
Alkyl halide
Alkane
R-X
R-H
R-OH
R-NH2
R-O-R’
>C=C<
>C≡C<
Nomenclature of multifunctional compounds
O
8
1
3
2
7
1
2
4
5
O
6
6-Benzyl-2-octanone
4
3
4-tertbutoxy-1-cyclohexene
Cl
4
3
OH
2
1
4
1
3
3-Benzyl-2-chloro-pent-4-en-1-ol
2
O
4-phenylcyclohexanal
5
O
2
HO
O
3
4
6
1
O
5
4
O
2
3
1
O
5
3-formyl-5-methylbenzoicacid
Methyl-3-oxohexanoate
H
CHO
O
5
O
4
2
OH
3
OH
2- formyl benzoic acid
1
OH
1,3- dihydroxypent-4-yn-2-one
4
O
1
O
3
NH2
2
Ethyl-3-aminobutanoate
H2N
O
3-aminocyclohexenone
NH2
OH
1
4
4
3
2
H 2N
O
3
2
O
5
1
2-Amino-3,3-dimethyl-butanal
3-Amino-2-isopropyl-pentanoic acid