Acid Anhydrides
- Formed from the removal of water (H2O) from 2 carboxylic acid molecules
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4936730/35398_682634.png)
- To name, remove ‘acid’ from the parent carboxylic acid name and replace with ‘anhydride’ for the (CO)2O bond system
- e.g. 2 molecules of ethanoic acid ➔ ethanoic anhydride + water
Do you remember the content of A-level Chemistry regarding Acylation of Acyl chloride?
- Acid Anhydride react in a similar way to acyl chlorides with alcohols, phenols, water, ammonia and amines!!
- Less reactive than acyl chlorides
- Useful for some lab preparations where acyl chlorides may be too reactive
Make sure you know all the Nucleophilic Addition-Elimination mechanisms below, they always appear in AS/A-level Chemistry exam! 👩🏫
Reaction of Acid Anhydrides with Water
- Hydrolysis
Acid anhydride + water ➔ 2 carboxylic acids
e.g. ethanoic anhydride + water ➔ 2 ethanoic acid
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4936730/724640_996776.png)
Reaction of Acid Anhydrides with Alcohols
Acid anhydride + alcohol ➔ ester + carboxylic acid
e.g. ethanoic anhydride + methanol ➔ methyl ethanoate + ethanoic acid
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4936730/608713_124439.png)
Reaction of Acid Anhydrides with Ammonia
Acid anhydride + ammonia ➔ primary amide + carboxylic acid
e.g. ethanoic anhydride + NH3 ➔ ethanamide + ethanoic acid
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4936730/499924_668008.jpeg)
Reactions of Acid Anhydrides with Amines
Acid anhydride + amine ➔ N-substituted amide + carboxylic acid
e.g. ethanoic anhydride + methyl amine ➔ N-methylethanamide + ethanoic acid
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4936730/17544_771793.png)
Nucleophilic Addition-Elimination Reaction:
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4936730/817448_957322.png)
This is the end of the topic!
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_60/4936730/22104_468110.gif)
Drafted by Cherry (Chemistry)