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4. The carbon atoms are numbered in the longest Carbon chain in such a way
that the carbon with the branch (substituent) has the lowest number.

5. When there aremore than one type of branches (e.g.-Ethyl, Methyl, etc.) the
branches (substituents)are written in alphabetical order.

6. To write the name of the branched structure-
We have to write the position of the branch (substituent), followed by the
name of the branch and then the parent hydrocarbon.

The following rules are further used -
A dash connects the number locations to the hydrocarbon name.

1. Prefixes are added to the branch name when more than 1 of the same type of
branch is present. The first few prefixes for these are:

2 3 4 5 6 7 8

di tri tetra pent hex hept oct

2. When different types of branches are present, list them in alphabetical order,
excluding numbering prefix (e.g. ethyl precedes dimethyl).
3. When branched hydrocarbons contain multiple bonds, the chain is numbered
relative to the locations of the multiple bond.

NOTE- Hydrocarbons having 1, 2 or 3 number of carbon atoms, do not form
branched structures & hence do not have isomers.

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