Triazenes

File:Dacarbazine.svg

Dacarbazine is a triazene used in the treatment of melanoma and Hodgkin's lymphoma.

File:Triacsin c.png

Triacsin C is a triazene made by certain bacteria species.

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 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 phenyldiazonium salt must be pre-made.

Azo N-coupling

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

Bis-triazene analogue of Tröger's base

Reactions and applications

Triazenes derived from primary amines engage in tautomerism. In the case of symmetric triazenes, the tautomers are identical.

Tautomerism of triazenes derived from primary amines

Triazenes can be converted to diazonium salts.

File:Triazene 1.tif

Triazenes used in the synthesis of thiophenols

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.