What reaction does "acidification followed by heat" give? (AAMC 5 #119)

[sc4s2cg]

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The question asks how to reverse a specific reaction (acid anhydride in water, but instead of water being the nucleophile OH- is), and the answer was acidification followed by heat. The answer section shows the mechanism, but doesn't say where heat comes in..so I'm wondering whether this is a common reaction?

 

[CodeRedDew]

The heat is just used to help bring the reaction to equilibrium. The reason why acidification should come first is because the carboxylic acid needs to be protonated, otherwise there is too much electron density around the carboxylic acid's carbonyl for it to act as an electrophile.

 

[sc4s2cg]

One of the other options was "just acidification". Why would this be incorrect?

 

[CodeRedDew]

Because the activation energy of the reaction is a bit too high; therefore, heat is needed to add that extra "umph" to the molecules so that the reaction can reach completion.


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