Final answer:
Tertiary amines do not undergo nucleophilic addition with carbonyls due to the lack of a hydrogen atom on the nitrogen, leading to the formation of ammonium salts instead of amides, and the decreased electrophilicity of the carbonyl carbon in carboxylic acids.
Step-by-step explanation:
The reason why tertiary amines do not go through nucleophilic addition with carbonyls is that tertiary amines lack a hydrogen atom connected to the nitrogen, which is necessary to form an intermediate that would go on to become an amide in a typical nucleophilic addition reaction. Instead of undergoing a nucleophilic addition, tertiary amines can engage in an acid-base reaction with carboxylic acids, resulting in the formation of ammonium salts rather than amides. The carbonyl carbon of carboxylic acids is less electrophilic compared to other carbonyl-containing compounds due to resonance stabilization, which further contributes to the decreased reactivity towards nucleophilic addition with tertiary amines.
Tertiary amines do not go through nucleophilic addition with carbonyls because they do not have a hydrogen attached to the nitrogen. Instead, an acid-base reaction occurs where the amine accepts a proton from the carboxylic acid, forming ammonium and carboxylate salts. The absence of a hydrogen on the nitrogen prevents the formation of amides.