If more than one functional group co-exist in the same compound, IUPAC directs the following functional group priorities.
Priority
1
Structure
Name
Nomenclature
Drop “e” at the end of alkane and replace with “oic acid“
Example
Propane -> Propanoic acid, octane -> octanoic acid
Name as Substituent
dioic acid (2 carboxylic acid), tricarboxyl acid (3 carboxylic acid).
Example
hexanedioic acid. 2-Hydroxypropane-1,2,3-tricarboxylic acid (citric acid)
2
Drop “e” at the end of alkane and replace it with “oate“
butane -> butanoate, decane -> decanoate
alkoxycarbonyl- e.g. methoxycarbonyl, ethoxycarbonyl, etc…
2-(Methoxycarbonyl)butanoic acid
3
Drop “e” at the end of alkane and replace it with “oyl halide“
pentane -> pentanoyl chloride, butane -> butanoyl bromide
halocarbonyl-
Methyl 4-(chlorocarbonyl)benzoate
4
Drop “e” at the end of alkane and replace it with “amide“
pentane -> pentanamide, hexane -> hexanamide
carbamoyl-
4-carbamoyl-5-methylhexanoic acid
5
Drop “e” at the end of alkane and replace it with “al“
ethane -> ethanal (acetaldehyde), heptane -> heptanal
oxo-
7-oxooctanoic acid
6
Drop “e” at the end of alkane and replace it with “one“
propane -> propanone, pentane -> 2-pentanone
oxo-
5-oxononanoic acid
7
Drop “e” at the end of alkane and replace it with “ol“
hexane -> hexanol, butane -> butanol
hydroxy-
3-hydroxypentanal
8
Drop “e” at the end of alkane and replace it with “amine“
octane -> octan-5-amine, propane -> propan-2-amine
amino-
(S)-2-Aminopentan-1-ol
9
Drop “ane” at the end of alkane and replace it with “ene“
heptane -> heptene
alkenyl – (e.g. ethenyl, propenyl)
1-(3-Butenyl)cyclohexene
10
Drop “ane” at the end of alkane and replace it with “yne“
pentane -> pentyne, octane -> octyne
alkynyl – (e.g. ethynyl, propynyl)
1-ethynylcyclohex-1-ene
N/A
(substituent naming), drop “ane” at the end of alkane and replace it with “oxy” for substituent
(substituent naming), ethane -> ethoxybutane (the shorter chain is the substituent for ether)
alkoxy- (e.g. propanoxy, butanoxy)
(R)-2-ethoxy-propan-1-ol
N/A
N/A
N/A
Drop “ine” at the end of halogen and replace it with “o“
fluorine -> fluoro, chlorine -> chloro, bromine -> bromo, iodine -> iodo. 1-bromopentane
N/A
N/A
N/A
Drop “ane” at the end of alkane and replace it with “yl“
methane -> methyl, ethane -> ethyl. Propylcyclohexane
Notes
For alkene and alkyne priorities,
See Alkene Alkyne Naming Priority Rules for more detail,
- *The priority for alkene and alkyne applies only as a tie breaker if no other higher priority functional group exists.
- *Otherwise, whichever the lowest locant takes priority for locant (carbon number) assignment if no other higher priority functional group exists.
- *”-yne” (alkyne) comes after “-ene” (alkene) for naming based on alphabetical order.
- When the vowel is followed by another vowel, the preceding vowel is dropped.
For example, pent-4-en-2-ol (pent + en + ol), NOT pent-4-ene-2-ol.
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