Triazenes

Triazenes are organic compounds that contain the functional group R1−N=N−NR2R3, where the R are each any of various types of substituent groups. Some anti-cancer medications and dyes are triazenes. Formally, the triazenes are related to the unstable chemical triazene, H2N−N=NH.

Production
Triazenes are prepared from the N-coupling reaction between diazonium salts and primary or secondary amines. The coupling reactions are typically mild, using a base such as sodium acetate, sodium carbonate, or sodium bicarbonate.

The diazonium reagents are themselves available starting from amines. For symmetrical triazenes derived from primary amines, partial diazotization gives a mixture of the original amine and its diazo derivative that then couple with each other. For example, 1,3-diphenyltriazene (PhN=N−NHPh) can be made from aniline in a one-pot reaction. For asymmetrical triazenes, for example (phenyldiazenyl)pyrrolidine (PhN=N−NC4H8), the diazonium salt must be pre-made.
 * Azo N coupling.jpg

Analogues of Tröger's base containing a symmetric pair of asymmetric triazene side-chains have been obtained similarly.


 * Bis-triazene.jpg

Reactions and applications
Triazenes derived from primary amines engage in tautomerism. In the case of symmetric triazenes, the tautomers are identical.
 * [[Image:triazen.png|300px|Tautomerism of triazenes derived from primary amines]]

Triazenes can be converted to diazonium salts.

Triazenes decompose in the presence of protonating or alkylating agents into quaternary amines and diazonium salts; as such triazenes have been used as an in situ source of diazonium that reacted with sodium sulfide to give the corresponding thiophenols. A strategy for the protection and deprotection of sensitive secondary amines is based on this principle.

Polymeric triazenes are applied as conductive and absorbent materials. Triazenes have been used in the synthesis of cinnoline, functionalized lactams, and coumarins.