In case the substituent on the parent chain is complex (i.e., it has branched chain), it is named as a substituted alkyl group by separately numbering the carbon atoms of this substituted alkyl group with the carbon atom attached to the parent chain being counted as 1. The name of such a substituent is always enclosed in brackets to avoid confusion with the numbers of the parent chain.
The prefix iso–and other related common ones are allowed by the IUPAC nomenclature for naming alkyl groups as long as they are not further substituted, whereas the prefixes sec– and tert–are not allowed.
If there are two chains of equal length, then the chain containing more number of side chains is selected.
