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There are some general rules which you should remember when naming organic compounds:

• The longest unbranched chain containing the functional group is the parent molecule, or simply the longest unbranched chain for alkanes. Remember that, the longest chain can go round a bend.
• Indicate the position of the functional group with a number, numbering from the end nearest the functional group.
• Name the branches, and indicate the number of branches.

Example

• Methyl indicates there is one carbon atom in the branch.
• Ethyl indicates there are two carbon atoms in the branch.
• The prefix 'di' indicates there are two branches.
• The prefix 'tri' indicates there are three branches.

Indicate the position of the branches with a number, numbering from the end nearest the functional group.

For more than one branch, the branches are identified in alphabetical order, ignoring any 'di', 'tri', etc, prefixes.

Each branch needs to be numbered individually, even if they are attached to the same carbon atom.

The rule is a comma between numbers, and a dash between numbers and letters.

Branched chain alkanes

The alkanes don't contain a functional group and so the branches are numbered from the end that gives the lowest set of position numbers for the branches.

Use the above rules to see how the names of the alkanes below are built up.