Diamine

A diamine is an organic compound with 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. Vicinal diamines (1,2-diamines) are a structural motif in many biological compounds and are used as ligands in coordination chemistry.

Aliphatic diamines

Linear

• 2 carbons: ethylenediamine (1,2-diaminoethane). Related derivatives include the N-alkylated compounds, 1,1-dimethylethylenediamine, 1,2-dimethylethylenediamine, 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

Derivatives of ethylenediamine are prominent:

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

Cyclic

• 1,4-Diazacycloheptane

• 
  Ethylenediamine
• 
  Cadaverine
• 
  PPD (para-phenylenediamine)
• 
  1,4-Diazacycloheptane

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:

• 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

External links

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