The reaction of acid chlorides and anhydrides with amines both require two equivalents of the amine, but for different reasons. why is this?

explain which one is correct and why?

1) acid chlorides are less reactive than anhydrides, so more amine is needed to speed up the reaction

2) the second equivalence of the amine deprotonates the carboxylic acid generated in the reaction of an amine with an anhydride

3) the second equivalence of the amine deprotonates the amide generated in the reaction of an amine with an anhydride

4) cl− can efficiently deprotonate amides while carboxylate anions are too weak bases for this