1,2,4-Triazole

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1,2,4-Triazole
Structural formula of 1,2,4-Triazole.svg
1,2,4-Triazole3d.png
Names
Preferred IUPAC name
1H-1,2,4-Triazole
Other names
1,2,4-Triazole pyrrodiazole
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.005.476 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C2H3N3/c1-3-2-5-4-1/h1-2H,(H,3,4,5) Yes check.svgY
    Key: NSPMIYGKQJPBQR-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C2H3N3/c1-3-2-5-4-1/h1-2H,(H,3,4,5)
    Key: NSPMIYGKQJPBQR-UHFFFAOYAZ
  • N1C=NC=N1
Properties
C2H3N3
Molar mass 69.00725
Appearancewhite solid
Density 1.439 g/cm3
Melting point 120 to 121 °C (248 to 250 °F; 393 to 394 K)
Boiling point 260 °C (500 °F; 533 K)
very soluble
Acidity (pKa)10,3
Basicity (pKb)11,8
Hazards
Flash point 140 °C (284 °F; 413 K)
Related compounds
Related compounds
 1,2,3-triazole imidazole
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

1,2,4-Triazole (as ligand in coordination compounds, Htrz abbreviation is sometimes used) 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. 1,2,4-Triazole and its derivatives find use in a wide variety of applications. [1]

Contents

Structure and properties

1,2,4-Triazole is a planar molecule. The C-N and N-N distances fall into a narrow range 136 - 132 picometers, consistent with the aromaticity. [2] Although two tautomers can be envisioned, only one exists practically speaking.

1,2,4-Triazole is amphoteric, being susceptible to both N-protonation and deprotonation in aqueous solution. The pKa of 1,2,4-triazolium (C2N3H4+) is 2.45. The pKa of the neutral molecule is 10.26. [3]

Synthesis and occurrence

Portion of the structure of {[Fe(triazolate)(triazole)2](BF4)}n. Fe(triazolate)3 (FIBCEA01).png
Portion of the structure of {[Fe(triazolate)(triazole)2](BF4)}n.

1,2,4-Triazoles can be prepared using the Einhorn–Brunner reaction or the Pellizzari reaction. Unsubstituted 1,2,4-triazole can be prepared from thiosemicarbazide by acylation with formic acid followed by cyclization of 1-formyl-3-thiosemicarbazide into 1,2,4-triazole-3(5)-thiol; oxidation of the thiol by nitric acid or hydrogen peroxide yields 1,2,4-triazole. [5]

1,2,4-Triazoles are featured in many kinds of drugs. [6] [7] Notable triazoles include the antifungal drugs fluconazole and itraconazole [8] and the plant growth regulator paclobutrazol. [9] Triazolate is a common bridging ligand in coordination chemistry. [10]

The 3,5‑dihydroxy derivative, known as urazole, sees extensive industrial use as a blowing agent. [11]

References

  1. ↑ Potts K. T. (1961). "The Chemistry of 1,2,4-Triazoles". Chemical Reviews . 61 (2): 87–127. doi:10.1021/cr60210a001.
  2. ↑ Jeffrey, G. A.; Ruble, J. R.; Yates, J. H. (1983). "Neutron diffraction at 15 and 120 K and ab initio molecular-orbital studies of the molecular structure of 1,2,4-triazole". Acta Crystallographica Section B: Structural Science. 39 (3): 388–394. Bibcode:1983AcCrB..39..388J. doi:10.1107/S010876818300258X.
  3. ↑ Garratt, Peter J. (1996). "1,2,4-Triazoles". Comprehensive Heterocyclic Chemistry II. pp. 127–163. doi:10.1016/B978-008096518-5.00080-0. ISBN   978-0-08-096518-5.
  4. ↑ Grosjean, Arnaud; Négrier, Philippe; Bordet, Pierre; Etrillard, Céline; Mondieig, Denise; Pechev, Stanislav; Lebraud, Eric; Létard, Jean-François; Guionneau, Philippe (2013). "Crystal Structures and Spin Crossover in the Polymeric Material [Fe(HTRZ)2(TRZ)](BF4) Including Coherent-Domain Size Reduction Effects" (PDF). European Journal of Inorganic Chemistry. 2013 (5–6): 796–802. doi:10.1002/ejic.201201121.
  5. ↑ C. Ainsworth (1960). "1,2,4-Triazole". Organic Syntheses. 40: 99. doi:10.15227/orgsyn.040.0099.
  6. ↑ Keri, Rangappa S.; Patil, Siddappa A.; Budagumpi, Srinivasa; Nagaraja, Bhari Mallanna (2015). "Triazole: A Promising Antitubercular Agent". Chemical Biology & Drug Design. 86 (4): 410–423. doi:10.1111/cbdd.12527. PMID   25643871. S2CID   9313180.
  7. ↑ Kaur, Ramandeep; Ranjan Dwivedi, Ashish; Kumar, Bhupinder; Kumar, Vinod (2016). "Recent Developments on 1,2,4-Triazole Nucleus in Anticancer Compounds: A Review". Anti-Cancer Agents in Medicinal Chemistry. 16 (4): 465–489. doi:10.2174/1871520615666150819121106. PMID   26286663.
  8. ↑ Kathiravan, Muthu K.; Salake, Amol B.; Chothe, Aparna S.; Dudhe, Prashik B.; Watode, Rahul P.; Mukta, Maheshwar S.; Gadhwe, Sandeep (2012). "The biology and chemistry of antifungal agents: A review". Bioorganic & Medicinal Chemistry. 20 (19): 5678–5698. doi:10.1016/j.bmc.2012.04.045. PMID   22902032.
  9. ↑ Tesfahun, Wakjira (January 1, 2018). Yildiz, Fatih (ed.). "A review on: Response of crops to paclobutrazol application". Cogent Food & Agriculture. 4 (1): 1–9. Bibcode:2018CogFA...425169T. doi: 10.1080/23311932.2018.1525169 . S2CID   134517280.
  10. ↑ Haasnoot, Jaap G. (2000). "Mononuclear, oligonuclear and polynuclear metal coordination compounds with 1,2,4-triazole derivatives as ligands". Coordination Chemistry Reviews. 200–202: 131–185. doi:10.1016/S0010-8545(00)00266-6.
  11. ↑ Jensen, James O. (Feb 2003). "Vibrational frequencies and structural determinations of urazole". Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 59 (3): 637–650. doi:10.1016/S1386-1425(02)00210-X.
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