Formation of amides from acid chlorides and amines
Description: Addition of primary or secondary amines (or ammonia) to acid chlorides results in amides.
Notes: Note that HCl is a byproduct in this reaction, although in practice excess amine is often used that will react with the HCl. (Trivia: this reaction is sometimes referred to as the Schotten-Baumann reaction).
This reaction works because Cl(–) is a better leaving group (i.e. weaker base) than the amine.
Notes: Acid (HCl) is a byproduct of the reactions shown here.
Mechanism: Addition of the amine to the acid chloride (Step 1, arrows A and B) results in a tetrahedral intermediate, which undergoes 1,2-elimination (Step 2, arrows C and D). Finally the nitrogen is deprotonated (Step 3, arrows E and F) to give the neutral amide.
Notes: Although Cl is shown as the base in step 3, the starting amine is a considerably stronger base and will probably be the base here.