Diamine

A diamine is an amine with exactly two amino groups. Diamines are used as monomers to prepare polyamides, polyimides and polyureas. In terms of quantities produced, 1,6-diaminohexane, a precursor to Nylon 6-6, is most important, followed by ethylenediamine.^[1] Vicinal diamines (1,2-diamines) are a structural motif in many biological compounds and are used as ligands in organometallic chemistry ^[2]

Aliphatic diamines

Linear aliphatic diamines

• 2 carbons: ethylenediamine (1,2-diaminoethane). Related derivatives include the N-alkylated compounds ethambutol and TMEDA.
• 3 carbons: 1,3-diaminopropane (propane-1,3-diamine)
• 4 carbons: putrescine (butane-1,4-diamine)
• 5 carbons: cadaverine (pentane-1,5-diamine)
• 6 carbons: hexamethylenediamine (hexane-1,6-diamine)

Branched aliphatic diamines

Derivatives of ethylenediamine are prominent:

• 1,2-diaminopropane, which is chiral.
• diphenylethylenediamine, which is C₂-symmetric.
• diaminocyclohexane, which is C₂-symmetric.

Xylylenediamines

Xylylenediamines are classified as alkylamines since the amine is not directly attached to an aromatic ring.

• o-xylylenediamine or OXD
• m-xylylenediamine or MXD
• p-xylylenediamine or PXD

Aromatic diamines

Three phenylenediamines are known:^[3]

• o-phenylenediamine or OPD
• m-phenylenediamine or MPD
• p-phenylenediamine or PPD. 2,5-Diaminotoluene is related to PPD but contains a methyl group on the ring.

Various N-methylated derivatives of the phenylenediamines are known:

• dimethyl-4-phenylenediamine, a reagent.
• N,N'-di-2-butyl-1,4-phenylenediamine, an antioxidant.

Examples with two aromatic rings include derivatives of biphenyl and naphthalene:

• 4,4'-diaminobiphenyl
• 1,8-diaminonaphthalene

• 

  Ethylenediamine

• 

  Cadaverine

• 

  PPD (para-phenylenediamine)

References

1. Karsten Eller, Erhard Henkes, Roland Rossbacher, Hartmut Höke "Amines, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry, 2005 Wiley-VCH Verlag, Weinheim. doi:10.1002/14356007.a02_001
2. Lucet, D., Le Gall, T. and Mioskowski, C. (1998), The Chemistry of Vicinal Diamines. Angew. Chem. Int. Ed., 37: 2580–2627. doi: 10.1002/(SICI)1521-3773(19981016)37:19<2580::AID-ANIE2580>3.0.CO;2-L
3. Robert A. Smiley "Phenylene- and Toluenediamines" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_405

External links

• Diamines at the US National Library of Medicine Medical Subject Headings (MeSH)
• Synthesis of diamines