Why Are Anhydrides More Reactive Than Amides?

Amides are the most stable, and the least reactive, because nitrogen is an effective donor of electrons to the carbonyl group. Anhydrides and esters are somewhat less stable, because oxygen is more electronegative than nitrogen and is a less effective donor of electrons.

Why are anhydrides so reactive?

Acid anhydrides are a source of reactive acyl groups, and their reactions and uses resemble those of acyl halides. Acid anhydrides tend to be less electrophilic than acyl chlorides, and only one acyl group is transferred per molecule of acid anhydride, which leads to a lower atom efficiency.

Why are amides the least reactive?

Amides are less reactive than are esters due to the fact that nitrogen is more willing to donate its electrons than is oxygen. As a result, the partial positive character of the carbonyl carbon is smaller in amides than in esters, making this system less electrophilic.