Triazenes are

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

s that contain the functional group −N(R)−N=N− (where R is H,

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...

aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromaticity, aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar ...

). Some anti-cancer medications and dyes are triazenes. Formally, triazenes are related to the unstable

triazene Triazene is an unsaturated inorganic compound having the chemical formula N3 H3. It has one double bond and is the second-simplest member of the azene class of hydronitrogen compounds, after diimide. Triazenes are a class of organic compoun ...

, H₂N−N=NH. The relationship is more theoretical than practical.

Production

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Triazenes are prepared from the ''N''-coupling reaction between diazonium salts and primary or secondary

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen Hydrogen is the chemical element wi ...

s. Symmetrical triazenes, for example 1,3-diphenyltriazene (PhN=N−NHPh), are prepared by the partial

diazotization Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General propert ...

of aromatic

primary amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starti ...

in this example, and the subsequent coupling reaction in the presence of

sodium acetate Sodium acetate, CH3COONa, also abbreviated Na O Ac, is the sodium salt of acetic acid. This colorless deliquescent salt has a wide range of uses. Applications Biotechnological Sodium acetate is used as the carbon source for culturing bacteria ...

. Asymmetrical triazenes, for example (phenyldiazenyl)pyrrolidine (PhN=N−NC₄H₈), are prepared from the ''N''-coupling reaction between diazonium salts and

secondary amines In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...

in presence of sodium carbonate or sodium bicarbonate. Bis-triazene carrying analogues of Tröger's base have been obtained similarly. : Azo N coupling

Tautomerism

Triazenes derived from primary amines engage in

tautomerism Tautomers () are structural isomers (constitutional isomers) of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hyd ...

. In the case of 1,3-diphenyltriazine, the tautomers are identical.

Reactions and applications

An important reaction of triazenes is their conversion 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 Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General properti ...

that reacted with sodium sulfide to give the corresponding

thiophenol Thiophenol is an organosulfur compound with the formula C6H5SH, sometimes abbreviated as PhSH. This foul-smelling colorless liquid is the simplest aromatic thiol. The chemical structures of thiophenol and its derivatives are analogous to phen ...

s. A strategy for the protection and deprotection of sensitive

secondary amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...

s 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

coumarin Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered h ...

References

{{reflist, 30em Functional groups