Amide formation from a carboxylic acid derivative and ammonia yields which product?

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Multiple Choice

Amide formation from a carboxylic acid derivative and ammonia yields which product?

The reaction at play is nucleophilic acyl substitution on an activated carboxyl derivative by ammonia. Ammonia donates its lone pair to the carbonyl carbon, the carbonyl pi electrons collapse, and the leaving group from the derivative departs. If the starting derivative is an acid chloride (a common activated form), the leaving group is chloride, so you end up with a primary amide, R–CO–NH2, and the byproduct HCl. That’s why the product is a primary amide after activation, with HCl formed. A secondary amide would require a secondary amine as the nucleophile, not ammonia. An amide anhydride isn’t the direct product of this ammonia substitution, and an ammonium salt of the carboxylic acid reflects protonation, not amide formation.

The reaction at play is nucleophilic acyl substitution on an activated carboxyl derivative by ammonia. Ammonia donates its lone pair to the carbonyl carbon, the carbonyl pi electrons collapse, and the leaving group from the derivative departs. If the starting derivative is an acid chloride (a common activated form), the leaving group is chloride, so you end up with a primary amide, R–CO–NH2, and the byproduct HCl. That’s why the product is a primary amide after activation, with HCl formed.

A secondary amide would require a secondary amine as the nucleophile, not ammonia. An amide anhydride isn’t the direct product of this ammonia substitution, and an ammonium salt of the carboxylic acid reflects protonation, not amide formation.

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