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?

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Answer 1 · 2016-02-01T00:32:15

You choose the chain that has more substituents.

Consider the molecule shown below.

Example

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 $C4$ $"C4"$ .

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 $C2$ $"C2"$ and a propyl group at $C4$ $"C4"$ .

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