IUPAC Nomenclature of Organic Chemistry - Order of Precedence of Groups

Order of Precedence of Groups

When compounds contain more than one functional group, the order of precedence determines which groups are named with prefix or suffix forms. The highest precedence group takes the suffix, with all others taking the prefix form. However, double and triple bonds only take suffix form (-en and -yn) and are used with other suffixes.

Prefixed substituents are ordered alphabetically (excluding any modifiers such as di-, tri-, etc.), e.g. chlorofluoromethane, not fluorochloromethane. If there are multiple functional groups of the same type, either prefixed or suffixed, the position numbers are ordered numerically (thus ethane-1,2-diol, not ethane-2,1-diol.) The N position indicator for amines and amides comes before "1", e.g. CH3CH(CH3)CH2NH(CH3) is N,2-dimethylpropanamine.

Priority Functional group Formula Prefix Suffix
1 Cations
e.g. Ammonium
NH4+		 -onio-
ammonio-		 -onium
-ammonium
2 Carboxylic acids
Carbothioic S-acids
Carboselenoic Se-acids
Sulfonic acids
Sulfinic acids
 –COOH
–COSH
–COSeH
–SO3H
–SO2H		 carboxy-
sulfanylcarbonyl-
selanylcarbonyl-
sulfo-
sulfino-		 -oic acid*
-thioic S-acid*
-selenoic Se-acid*
-sulfonic acid
-sulfinic acid
3 Carboxylic acid derivatives
Esters
Acyl halides
Amides
Imides
Amidines
–COOR
–COX
–CONH2
–CON=C<
–C(=NH)NH2
R-oxycarbonyl-
halocarbonyl-
carbamoyl-
-imido-
amidino-
-R-oate
-oyl halide*
-amide*
-imide*
-amidine*
4 Nitriles
Isocyanides		 –CN
–NC		 cyano-
isocyano-		 -nitrile*
isocyanide
5 Aldehydes
Thioaldehydes		 –CHO
–CHS		 formyl-
thioformyl-		 -al*
-thial*
6 Ketones
Thiones
Selones
Tellones
 =O
=S
=Se
=Te		 oxo-
sulfanylidene-
selanylidene-
tellanylidene-		 -one
-thione
-selone
-tellone
7 Alcohols
Thiols
Selenols
Tellurols
 –OH
–SH
–SeH
–TeH		 hydroxy-
sulfanyl-
selanyl-
tellanyl-		 -ol
-thiol
-selenol
-tellurol
8 Hydroperoxides
Peroxols
Thioperoxols (Sulfenic acid)
Dithioperoxols
-OOH
-SOH
-SSH
hydroperoxy-
hydroxysulfanyl-
disulfanyl-
-peroxol
-SO-thioperoxol
-dithioperoxol
9 Amines
Imines
Hydrazines		 –NH2
=NH
–NHNH2		 amino-
imino-
hydrazino-		 -amine
-imine
-hydrazine
10 Ethers
Thioethers
Selenoethers		 –O–
–S–
–Se–		 -oxy-
-thio-
-seleno-
11 Peroxides
Disulfides		 –OO–
–SS–		 -peroxy-
-disulfanyl-

Read more about this topic:  IUPAC Nomenclature Of Organic Chemistry

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