So far, we’ve discussed carboxylic acids and the reaction leading to the formation of derivatives. While we do know what these derivatives are, there is a special set of rules when it comes to naming carboxylic acid derivatives. In this article, we’ll try to keep it as understandable as possible so you won’t get too overwhelmed.
Naming carboxylic acids is quite easy, especially for acyl halides and nitriles. Other derivatives require a little bit more practice but it’s nothing that you couldn't handle!
I. Amides
Amides are functional groups with an acyl group bonded to nitrogen. Its general formula is R(C=O)NR’R”. In this formula, we acknowledge that R can be a hydrocarbon chain, hydrogen, or other functional group.
Here’s a summary of how naming rules should apply for amides:
II. Esters
Esters have a general formula of RCOOR’. It’s characterized by a double bond between oxygen and carbon bonded to another oxygen in a single bond followed by an alkyl or aryl group. It is formed through the reaction of acid and alcohol.
These compounds are named with the alkyl group starting from the carbonyl and an -oate suffix.
Here’s how to do it:
First, select the oxygen that connects the carbonyl and the chain without a carbonyl.
2. Count the number of carbons beginning from the oxygen in step 1.
3. Name the ester using this format: [Alkyl away from the carbonyl] [Alkane with the carbonyl]
[octyl] [ethane]
4. Change the suffix from -e to -oate.
[octyl] [ethanoate]
III. Anhydrides
Anhydrides form when two carboxylic acids merge and lose water in the process. In naming anhydrides, we have to be wary about the compound we want to name since these can be symmetrical or unsymmetrical
Symmetrical
Naming symmetrical anhydrides is quite easy. We remove “acid” from the parent compound and replace it with “anhydride”
Let’s try naming this anhydride:
This chain has two 4-carbon chains on either side. We name this as butyric anhydride.
Here are a few examples:
Unsymmetrical
For unsymmetrical anhydrides, we name each carboxylic acid separately and arrange the names alphabetically followed by the word “anhydride.”
For this, we have a 3-carbon chain on one side and a 2-carbon chain on the other. Therefore, we can name this ethanoic propanoic anhydride.
IV. Conclusion
Naming other carboxylic acid derivatives can be simplified in this table:
V. Practice Questions
Sample Practice Question 1
Which of the following compounds is incorrectly named?
A)
B)
C)
D)
Ans. D
Sample Practice Question 2
Name the compound:
A) 3-Methylbenzamide
B) 4-Methylbenzamide
C) 3-Ethylbenzamide
D) 4-Ethylbenzamide
Ans. B
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