Diamines are used as monomers to prepare polyamides, polyimides, and polyureas.
[1] In terms of quantities produced, 1,6-diaminohexane (a precursor to Nylon 6-6) is most important, followed by ethylenediamine.
[2] Vicinal diamines (1,2-diamines) are a structural motif in many biological compounds and are used as ligands in coordination chemistry.
[3] Geminal diamines (1,1-diamines) are usually reactive intermediates in transimination reactions and the reduction of amidines, in aqueous conditions they preferentially eliminate the less basic amine to leave an iminium ion.
Xylylenediamines are classified as alkylamines since the amine is not directly attached to an aromatic ring.