Iupac nomenclature for organic compounds

IUPAC Rules for Nomenclature:

(i).Root words:

C1 -Meth, C2 -Eth, C3-Prop ,C4-Buta, C5- Penta, C6- Hexa, C7- Hepta,C8- Octa,C9-Nona,C10-Deca

(ii).Primary suffix:

                               Alkane   - C-C-       -ane
                               Alkene     -C=C-       -ene
                             alkyne       -C=_C-      -yne
1.Longest sum rule:
the longest continuous chain of carbon atoms is considered for naming the carbon compound, the prefix in the name of the compound depends on the number of carbons present in the compound.

2.Least Sum Rule:
In numbering the carbon atoms in the parent chain start at the end which  results in the use of lowest number for the substituent carbon atoms.

3.When identical substituent are present on the same carbon atom,the position of the substituent is repeated

4.if the carbon chain contain 2 or more than 2 identical substituent,then di- tri- tetra- words are used to indicate the number of substituents.

5.If the number of different groups are attached to the parent the chain ,then the naming is done in two ways:
(i). according to the IUPAC rules
(ii) the name is given to the compound following the increase in order of complexity of the group

6.when a carbon compound  has carbon chain having the same no.of carbon atoms,they having more number of branches is selected as the parent chain

7 If a carbon chain contains substituents which are at equal distance either from left are right side counting is done in such a way that the least number is given to substituens

8 When the main carbon chain in a carbon compound carries a branch which again contains a substituent,the position of the substituent in the branch is written in the brackets.

IUPAC Rules for naming Poly functional compounds:

A molecule can contain more than one functional group called as polyfunctional group,the functional group which specifies its class is called the principle functionl group the other functional groups are refered to as ' substituents'

Nomenclature Priority for determining the principle functional group.Highest priority at the top.
suffixes for functional groups:
Caboxylic acid     -COOH   (  -oic acid )
sulphonic acid    -SO3H  (sulphonic acid)
Ester                     - COOR ( -alkyl -  oate)
Acid halide           -COX  ( -oyl chloride)
amide                  -CO NH2 ( -amide)
nitrile                  -CN (-nitrile)
aldehyde         -CHO  (-al)
ketone             -CO-   (-one)
alcohol          -OH ( -ol)
amine             - NH2  (-amine)
ethers            -O-  (ether)
alkene          -C=C- (ene)
alkyne         -C=_C-   (-yne)


1.Identify principal functional group.this gives class name of  the structure.

2. Number the longest chain containing the principal functional group from the end closer to it.

3.Write the parent name corresponding to the no.of cabons in the longest chain.

4 Arrange the substituents names with position numbers in alphabetical order.

5.Prefix substituent name with the parent name.

6.The following functional groups are always named as substituents ,their names prefixed with the parent name.
ex:Cl - chloro; Br - bromo ;I -iodo ;F-flouro ;CN - cyano ; R - alkyl, OR - alkoxy ; NH2 -amine;NO2 -nitro  etc..

IUPAC Nomenclature rules with example:

7.Identify double/triple bonds. Number them with the number of the carbon atom at the head of the bond (i.e the carbon atom with the lesser number that it is attached to). For example a double bond between carbon atoms 3 and 4 is numbered as 3-ene. Multiple bonds of one type (double/triple) are named with a prefix (di-, tri-, etc.). If both types of bonds exist, then use "ene" before "yne" e.g. "6 13 diene 19 yne". If all bonds are single, use "ane" without any numbers or prefixes.

8. Arrange everything like in  this way: Group of side chains and secondary functional groups with numbers made in step 3 + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers.
      Wherever it says "with numbers", it is understood that between the word and the numbers, you use the prefix(di-, tri-)

   9. Add punctuation:
         1. Put commas between numbers (2 5 5 becomes 2,5,5)
         2. Put a hyphen between a number and a letter (2 5 5 trimethylhexane becomes 2,5,5-trimethylhexane)
         3. Successive words are merged into one wordform (trimethyl hexane becomes trimethylhexane)
            NOTE: IUPAC uses one-word names throughout. This is why all parts are connected.

Ex:  CH3-CH(OH)-CH2-CH(CH3)-COOH

         5       4             3         2               1

From priority order -COOH  have higher rank ,therefore -COOH is the principal functional group.the structure is named as a carboxylic acid.
Longest chain : 5 carbons
so,parent name = pentanoic acid
Order of substituent 4-hydroxy -2-methyl
therefore,Name of the compound : 4-Hydroxy-2-methyl pentanoic acid.