1,2,3-Triazole

1,2,3-Triazole
Names
	IUPAC name 1H-1,2,3-triazole
	Other names 1,2,3-triazole
Identifiers
CAS Number	288-36-8 ;
3D model (JSmol)	Interactive image; Interactive image;
ChEBI	CHEBI:35566 ;
ChemSpider	60839 ;
ECHA InfoCard	100.128.405
CompTox Dashboard (EPA)	DTXSID30870495 ;
	InChI InChI=1S/C2H3N3/c1-2-4-5-3-1/h1-2H,(H,3,4,5) Key: QWENRTYMTSOGBR-UHFFFAOYSA-N ; InChI=1/C2H3N3/c1-2-4-5-3-1/h1-2H,(H,3,4,5) Key: QWENRTYMTSOGBR-UHFFFAOYAF;
	SMILES C1=CN=NN1; c1cnn[nH]1;
Properties
Chemical formula	C2H3N3
Molar mass	69.0654
Appearance	colorless liquid
Density	1.192
Melting point	23 to 25 °C (73 to 77 °F; 296 to 298 K)
Boiling point	203 °C (397 °F; 476 K)
Solubility in water	very soluble
Acidity (pKa)	9.4
Basicity (pKb)	1.2
Related compounds
Related compounds	1,2,4-triazole imidazole
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

1,2,3-Triazole is one of a pair of isomeric chemical compounds with molecular formula C₂H₃N₃, called triazoles, which have a five-membered ring of two carbon atoms and three nitrogen atoms. 1,2,3-Triazole is a basic aromatic heterocycle.^[1]

Substituted 1,2,3-triazoles can be produced using the azide alkyne Huisgen cycloaddition in which an azide and an alkyne undergo a 1,3-dipolar cycloaddition reaction.

It is a surprisingly stable structure compared to other organic compounds with three adjacent nitrogen atoms. However, flash vacuum pyrolysis at 500 °C leads to loss of molecular nitrogen (N₂) leaving a three-member aziridine ring. Certain triazoles are relatively easy to cleave due to ring–chain tautomerism. One manifestation is found in the Dimroth rearrangement.

1,2,3-Triazole finds use in research as a bioisostere in medicinal chemistry^[2] building block for more complex chemical compounds, including pharmaceutical drugs such as mubritinib and tazobactam.

The 2H-1,2,3-triazole tautomer is the major form in aqueous solution.^[3]

References

^ Gilchrist, T.L. (1987). Heterocyclic chemistry. Prentice Hall Press. ISBN 0-582-01421-2.
^ Bonandi, E.; Christodoulou, M. S.; Fumagalli, G.; Perdicchia, D.; Rastelli, G.; Passarella, D. (2017). "The 1,2,3-triazole ring as a bioisostere in medicinal chemistry". Drug Discov Today. 22 (10): 1572–1581. doi:10.1016/j.drudis.2017.05.014. PMID 28676407.
^ Albert, Adrien; Taylor, Peter J. (1989). "The tautomerism of 1,2,3-triazole in aqueous solution". Journal of the Chemical Society, Perkin Transactions 2 (11): 1903–1905. doi:10.1039/P29890001903.

[1] Gilchrist, T.L. (1987). Heterocyclic chemistry. Prentice Hall Press. ISBN 0-582-01421-2.

[2] Bonandi, E.; Christodoulou, M. S.; Fumagalli, G.; Perdicchia, D.; Rastelli, G.; Passarella, D. (2017). "The 1,2,3-triazole ring as a bioisostere in medicinal chemistry". Drug Discov Today. 22 (10): 1572–1581. doi:10.1016/j.drudis.2017.05.014. PMID 28676407.

[3] Albert, Adrien; Taylor, Peter J. (1989). "The tautomerism of 1,2,3-triazole in aqueous solution". Journal of the Chemical Society, Perkin Transactions 2 (11): 1903–1905. doi:10.1039/P29890001903.

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