Beyond Science returns with this A Level blog on Branched Alkanes. Learn about how the main carbon chain, also known as the parent chain, and how the position of an alkyl chain along the parent chain is indicated in the compound’s name!
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Branched alkanes contain hydrocarbon side chains bonded to carbon atoms at various
positions along the main chain. The main carbon chain is known as the parent chain and
can be identified by finding the longest continuous chain of carbon atoms. Any chains which
branch off from the parent chain are known as alkyl chains. The length of the alkyl chain
is denoted in a compound’s name by the following prefixes:
| Number of Carbon Atoms in Alkyl Side Chain | Nomenclature of Alkyl Chain |
|---|---|
| 1 | methyl- |
| 2 | ethyl- |
| 3 | propyl- |
| 4 | butyl- |
The position of the alkyl chain along the parent chain is also indicated in the compound’s
name as shown in the examples below. If there is more than one side chain present, they
appear in the compound’s name alphabetically.
| methylpropane | 3-ethylpentane | 3-ethyl-2-methylpentane |
|---|---|---|
 |  |  |
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