Naming of Haloalkanes

Naming of haloalkanes follows the exact same general guidelines that were introduced earlier in this chapter. Just as before, choose the longest chain of uninterrupted carbon atoms as the parent chain. Now however, it is important to give preference to choosing parent chain with the halogen on it. For example, if you are asked about the naming of the following haloalkane, you might have difficulty deciding the parent chain.

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Halogens have higher priority in naming than alkanes. Therefore, we must give preference to halogens in naming of haloalkanes and ensure they are located off the parent chain.

The difficulty in the naming of haloalkanes is choosing the proper parent chain

 

 

 

 

 

 

 

 

 

When halogens are substituents, use the following terms for their nomenclature:

 

Halogen Substituent Name
fluorine fluoro-
chlorine chloro-
bromine bromo-
iodine iodo-

 

Here are a few other haloalkanes with their names indicated.

 

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Example

Name the following haloalkane:

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Answer

1-bromo-5-chloro-4-fluoro-7-iodononane

 

In larger molecules, it is important to make sure that the substituents overall have the lowest numbing possible.

First, we must identify the parent chain, which is the carbon chain going horizontally across the page here. There are 9 carbons in this chain, so we know the prefix will be non-, and because the molecule consists of only carbon, hydrogen, and halogens, the suffix is –ane, so the parent chain is named nonane. Let’s examine the two possibilities for numbering the substituents:

 

29We are then left with 4 substituents coming off the parent chain: a bromo, a fluoro, a chloro, and an iodo. The chain is numbered from left to right to minimize the numbering of the substituents. Therefore, the 4 substituents in order from left to right are 1-bromo, 4-fluoro, 5-chloro, and 7-iodo.

 

This image details the steps of the naming of haloalkanes

 

 

 

Then place the substituents and the parent chain name together, alphabetizing the substituents and the full name of the molecule is 1-bromo-5-chloro-4-fluoro-7-iodononane.