triazenes
{{Short description|Organic compounds with a diazoamino group}}
image:Dacarbazine.svg is a triazene used in the treatment of melanoma and Hodgkin's lymphoma.{{cite web|title=Dacarbazine|url=https://www.drugs.com/monograph/dacarbazine.html|publisher=The American Society of Health-System Pharmacists|access-date=8 December 2016|url-status=live|archive-url=https://web.archive.org/web/20170911072711/https://www.drugs.com/monograph/dacarbazine.html|archive-date=11 September 2017}}]]
Image:Triacsin c.png 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.{{Cite journal |last=Suleymanov |first=Abdusalom A. |last2=Severin |first2=Kay |date=2021-03-22 |title=Vinyl and Alkynyl Triazenes: Synthesis, Reactivity, and Applications |url=https://onlinelibrary.wiley.com/doi/10.1002/anie.202011031 |journal=Angewandte Chemie International Edition |language=en |volume=60 |issue=13 |pages=6879–6889 |doi=10.1002/anie.202011031 |issn=1433-7851}} Some medications and dyes are triazenes.{{Ullmann|first=Horst|last=Berneth|title=Methine Dyes and Pigments|year=2008|doi= 10.1002/14356007.a16_487.pub2}} 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.{{cite journal|title=Synthesis of Symmetrical trans-Stilbenes by a Double Heck Reaction of (Arylazo)amines with Vinyltriethoxysilane: trans-4,4′-Dibromostilbene|first1=Saumitra|last1=Sengupta|first2=Subir K.|last2=Sadhukhan|journal=Organic Syntheses|year=2002|volume=79|page= 52|doi=10.15227/orgsyn.079.0052}} 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.{{cite journal|last1=Kazem-Rostami|first1=M.|last2=Khazaei|first2=A.|last3=Moosavi-Zare|first3=A. R.|last4=Bayat|first4=M.|last5=Saednia|first5=S.|year=2012|title=Novel One-Pot Synthesis of Thiophenols from Related Triazenes under Mild Conditions|journal=Synlett|volume=23|issue=13|pages=1893–1896|doi=10.1055/s-0032-1316557|s2cid=196805424 }}{{cite journal|author=Hartman, W. W.; Dickey, J. B.|year=1934|title=Diazoaminobenzene|journal=Organic Syntheses|volume=14|pages=24|doi=10.15227/orgsyn.014.0024}} For asymmetrical triazenes, for example (phenyldiazenyl)pyrrolidine (PhN=N−NC4H8), the phenyldiazonium salt must be pre-made.
Analogues of Tröger's base containing a symmetric pair of asymmetric triazene side-chains have been obtained similarly.{{Cite journal|last=Kazemostami|first=Masoud|date=2017|title=Facile preparation of Ʌ-shaped building blocks: Hünlich-base derivatization|journal=Synlett|volume=28|pages=1641–1645|doi=10.1055/s-0036-1588180|s2cid=99294625}}
Reactions and applications
Triazenes derived from primary amines engage in tautomerism. In the case of symmetric triazenes, the tautomers are identical.
Triazenes can be converted to diazonium salts.{{cite journal|last1=Kimball|first1=D. B.|last2=Haley|first2=M. M.|year=2002|title=Triazenes: A Versatile Tool in Organic Synthesis|journal=Angewandte Chemie International Edition|volume=41|issue=18|pages=3338–51|doi=10.1002/1521-3773(20020916)41:18<3338::AID-ANIE3338>3.0.CO;2-7|pmid=12298030}}
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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.{{Cite journal|last1=Lazny|first1=R.|last2=Poplawski|first2=J.|last3=Köbberling|first3=J.|last4=Enders|first4=D.|last5=Bräse|first5=S.|date=1999|title=Triazenes: A Useful Protecting Strategy for Sensitive Secondary Amines|journal=Synlett|volume=1999|issue=8|pages=1304–1306|doi=10.1055/s-1999-2803}}
Polymeric triazenes are applied as conductive and absorbent materials.{{Cite journal|first1=A.|last1=Khazaei|first2=A.|last2=Zare|first3=A. R.|last3=Moosavi-Zare|first4=M.|last4=Sadeghpour|first5=A.|last5=Afkhami|date=2013|title=Synthesis, characterization, and application of a triazene-based polysulfone as a dye adsorbent|journal=Journal of Applied Polymer Science|volume=129|issue=6|pages=3439–3446|doi=10.1002/app.39069}} Triazenes have been used in the synthesis of cinnoline, functionalized lactams, and coumarins.