4.2 Nomenclature of Alkanes

What are the first 3 steps to naming organic molecules?

(more steps coming; these are the 4 base ones.)

Step 1: Identify the parent chain

Step 2: identify any side chains

Step 3: Assign a numerical number to each carbon in the parent chain beginning with the side closest to the side chains.

What is the fourth step to naming organic molecules

Step 4: Name the molecule by putting the location of the side chains, followed by a hyphen, before the name of the side chains and then the name of the parent chain.

• ex) 2,4-dimethylheptane

2 and 4 are the locations of both methyl side chains

• If there are different side chains, you name them in alphabetical order.

"Heptane" is the name of the parent chain because in this scenario the parent chain has 7 carbons.

How do we name side chains (branched organic molecules)

When CH₄, methane, binds to the parent chain, it must lose a carbon to form a carbon-carbon bond, therefor it is no longer capable of being called methane, so we label it as methyl instead to indicate it is a single-carbon side chain.

• This applies for all prefixes for ethane → ethyl, propane → propyl….

How to name Alkyl Halides

More details in notes, but these are essentially when a bromine, fluorine, iodine, or chlorine binds to the parent chain.

When this occurs, their name changes from the name of the halogen to a functional group name.

• Bromine → Bromo

• Iodine → Iodo

• Chlorine → Chloro

• Fluorine → Fluoro