In the chemical nomenclature, the IUPAC nomenclature of organic chemistry is the systematic method for naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It was first published in the book named Nomenclature of Organic Chemistry. There also exists an IUPAC nomenclature of inorganic chemistry since every organic compound also has a name for creation of an unambiguous structural formula.
Except to give an unambiguous and the absolute definition of a compound, the official IUPAC nomenclature is not always used. Trivial or common name can be used too.
RULES FOR IUPAC SYSTEM OF NOMENCLATURE
1) The longest chain rule
The parent hydrocarbon is the longest continuous chain of carbon atoms. The compound thus named is a derivative of the parent hydrocarbon.
2) The lowest number rule
The parent carbon chain is numbered as beginning from either end so that other side chain or substituents that are linked to the parent carbon chain gets indicated by the lowest possible number. IUPAC names for alkanes get assigned by adding the suffix “-ane” to the root name of the parent hydrocarbon. Side chains and substituent are indicated by their names.
3) Suitable prefix
In case of two or more identical substituent, a prefix di for two, tri for three is placed before the name of the very compound.
4) Alphabetical order
In case of a compound having more than one type of substituent, then the name of the substituent is written in an alphabetical order.
Cyclic alkanes are the ones that are named by adding a prefix ‘cyclo’ before the corresponding alkane’s name.
6) The parent functional group is identified and given highest order of precedence.
The final name should be something like:
#,#-di<side chain>-#-<secondary functional group>-#-<side chain>-#,#,#-tri<secondary functional group><parent chain prefix><If all bonds are single bonds, use “ane”>-#,#-di<double bonds>-#-<triple bonds>-#-<primary functional group>
Here, # denotes number.
These are the groups that provide centres of the chemical reactivity in the molecules. The property of any organic compounds is heavily dependent on the functional group. Compounds having same functional groups inherit similar properties owing to their belonging to the same group, the reason for their reactivity.
In a homologous series, each and every member has the same functional group. Therefore, to study the organic chemistry, we have to study the properties of the functional group. These properties would be present in each and every other compound of the same functional group.