# If in the given structure of a compound there are two chains with an equal number of carbon atoms how do you understand which is the parent chain?

Feb 1, 2016

You choose the chain that has more substituents.

#### Explanation:

Consider the molecule shown below.

If you count from the left hand end and go up, there are 8 carbons in the chain.

The chain will have an isobutyl group at $\text{C4}$.

If you count from the left hand end and go straight across, there are 8 carbons in the chain.

The chain will have a methyl group at $\text{C2}$ and a propyl group at $\text{C4}$.

The second choice has more substituents, so it becomes the parent chain for naming purposes.