Quick Notes Acid Anhydrides
- Acid anhydrides are made from two carboxylic acids joined together in a condensation reaction.
- Acid anhydrides react in similar ways to acyl chlorides, but they are less reactive, making them safer to use.
- Acid Anhydride + Alcohol → Ester + Carboxylic Acid
Full Notes Acid Anhydrides
Acid anhydrides are made from two carboxylic acid groups joined together.
![functional group acid anhydride](images/A2Organic/organic/organicchemistryacidanhydrides1blank.png)
To form an acid anhydride, a water molecule is lost in a condensation reaction between two carboxylic acids. This is why acid anhydrides are called anhydride – lack of water.
![reaction between carboxylic acids to form acid anhydride and water](images/A2Organic/organic/organicchemistryacidanhydrides2.png)
Reactions of Acid Anhydrides
Acid anhydrides react in a similar way to acyl chlorides, but they are less reactive. Being less reactive is actually very useful because they are far safer (and cheaper) to use in reactions.
![acid anhydride and alcohol to form ester and carboxylic acid](images/A2Organic/organic/organicchemistryacidanhydrides3.png)
Reacting an acid anhydride with an alcohol produces an ester and a carboxylic acid. This is essentially the same reaction as with an acyl chloride (see Acyl Chlorides), but rather than releasing HCl, a carboxylic acid is formed.