35.1.2—Formation of polyamides

A diamine and a dicarboxylic acid (or dioyl chloride) can condense to form a polyamide. Aminocarboxylic acids and amino acids can also self-condense when each molecule supplies both groups.

Each amide link forms between –NH₂ and –COOH/–COCl, releasing water or HCl. Two functional groups on each linking unit allow chains to continue.

Hexane-1,6-diamine plus hexanedioic acid gives a nylon-like chain containing –NH(CH₂)₆NHCO(CH₂)₄CO– repeats.

A mixture of a monoamine and monoacid makes a small amide, not a high polymer; chain growth requires bifunctionality.