1,2,3-Triazole
Names
Preferred IUPAC name
1H-1,2,3-Triazole
Other names
1,2,3-Triazole
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.128.405
EC Number
  • 608-262-3
UNII
  • InChI=1S/C2H3N3/c1-2-4-5-3-1/h1-2H,(H,3,4,5) checkY
    Key: QWENRTYMTSOGBR-UHFFFAOYSA-N checkY
  • InChI=1/C2H3N3/c1-2-4-5-3-1/h1-2H,(H,3,4,5)
    Key: QWENRTYMTSOGBR-UHFFFAOYAF
  • C1=CN=NN1
  • c1cnn[nH]1
Properties
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)
very soluble
Acidity (pKa) 9.4[1]
Basicity (pKb) 1.2[1]
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
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).
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Infobox references

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.[2]

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. Under thermal conditions, regioselectivity is substrate dependent. Selectivity can be increased with metal catalysts, which have the added benefit of reacting without excessive or extensive heating. Copper catalyzed cycloadditions favor 1,4-disubstituted triazoles, Ruthenium catalyzed cycloaddition favor 1,5-disubstituted triazoles. This chemistry was expanded by Zhu et al. in 2018 wherein they report a two-step sequence from a terminal alkyne to 4-cyano 1,5-disubstituted triazoles. [3]

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[4] 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.[5]

References

  1. 1 2 "1,2,3-triazole - an overview". Comprehensive Heterocyclic Chemistry. 1984.
  2. ↑ Gilchrist, T.L. (1987). Heterocyclic chemistry. Prentice Hall Press. ISBN 0-582-01421-2.
  3. ↑ Liu, P.; Clark, R.; Zhu, L. (2018). "Synthesis of 1‑Cyanoalkynes and Their Ruthenium(II)-Catalyzed Cycloaddition with Organic Azides to Afford 4‑Cyano-1,2,3-triazoles". J. Org. Chem. 83 (9): 5092–5103. doi:10.1021/acs.joc.8b00424. PMID 29630830.
  4. ↑ 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. hdl:11380/1153568. PMID 28676407.
  5. ↑ 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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