IUPAC name format

IUPAC name format

Cyclic Compound:
S. prefix + P. prefix + word root + P. suffix + S. suffix
Acyclic Compound:
Prefix + word root + P. suffix + S. suffix


1. Rules for selection of Carbon chain (parent chain)

Longest chain rule:  select longest continuous chain of carbon atom

Larger number of side chain:

If two c-chain have equal length (i.e having same number of c-atom), select c-chain which has greater number of side chains.


2.  Rules for numbering C-atom in parent chain

If only one side chain or substituent is present, the numbering of carbon atom is carried out in such a way that the carbon atom which carries substituent on side chain gets the lowest possible number.


If more than one side chain or substituent is present then the numbering of c-atom is carried in such a way that the sum of locant should be lowest. This rule is also known as lowest sum rule.

Note: Locant is the position or location number of side chain or substituent in parent chain.Larger-number-of-side-chain-rule2

If two different substituent are present at equal position from two ends then the substituent which comes first in alphabetical order gets the lowest position number.Larger-number-of-side-chain-rule3