Final answer:
Hexamethylenediamine and adipic acid react to form the polyamide nylon 66 through a condensation reaction, which also eliminates water molecules.
Step-by-step explanation:
Hexamethylenediamine and adipic acid undergo a condensation reaction to create a type of polyamide known as nylon 66. During this reaction, each hexamethylenediamine molecule, which has two amino groups, reacts with adipic acid, a diacid with two carboxyl groups, leading to the elimination of water molecules. This process forms amide bonds, resulting in a long, repeating polyamide chain characteristic of nylon 66.
The reaction process is similar to amidation, where an amide is formed from a carboxylic acid and an amine, with water being the byproduct. This specific type of polymerization yields two molecules of water per repeat unit, corresponding to the two amide groups formed, hence the name nylon 6,6, which indicates the number of carbon atoms in the diamine and diacid monomers, respectively.