View source for 1,2,4-Triazole

{{chembox
| Watchedfields = changed
| verifiedrevid = 477202680
| ImageFileL1 = Structural formula of 1,2,4-Triazole.svg
| ImageFileR1 = 1%2C2%2C4-Triazole3d.png
| PIN = 1''H''-1,2,4-Triazole
| OtherNames = 1,2,4-Triazole pyrrodiazole
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 46077
| ChemSpiderID = 8900
| InChI = 1/C2H3N3/c1-3-2-5-4-1/h1-2H,(H,3,4,5)
| InChIKey = NSPMIYGKQJPBQR-UHFFFAOYAZ
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 15571
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C2H3N3/c1-3-2-5-4-1/h1-2H,(H,3,4,5)
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = NSPMIYGKQJPBQR-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 288-88-0
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 10MS0Y1RDI
| PubChem = 9257
| SMILES = N1C=NC=N1
}}
| Section2 = {{Chembox Properties
| Formula = C{{sub|2}}H{{sub|3}}N{{sub|3}}
| MolarMass = 69.00725
| Appearance = white solid
| Density = 1.439 g/cm<sup>3</sup>
| MeltingPtC = 120 to 121
| BoilingPtC = 260
| Solubility = very soluble
| pKa = 10,3
| pKb = 11,8
}}
| Section7 = {{Chembox Hazards
| MainHazards =
| FlashPtC = 140
| AutoignitionPtC =
}}
| Section8 = {{Chembox Related
| OtherCompounds = [[1,2,3-triazole]] [[imidazole]]
}}
}}
'''1,2,4-Triazole''' (as ligand in coordination compounds, '''Htrz''' abbreviation is sometimes used) is one of a pair of [[isomer]]ic [[chemical compound]]s with [[molecular formula]] C{{sub|2}}H{{sub|3}}N{{sub|3}}, called [[triazole]]s, 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.<ref>{{cite journal| title =  The Chemistry of 1,2,4-Triazoles.| author = Potts K. T.| journal = [[Chemical Reviews]]| volume = 61| issue = 2| pages = 87–127| year = 1961| doi = 10.1021/cr60210a001}}</ref>
==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.<ref>{{cite journal |doi=10.1107/S010876818300258X|title=Neutron diffraction at 15 and 120 K and ab initio molecular-orbital studies of the molecular structure of 1,2,4-triazole|year=1983|last1=Jeffrey|first1=G. A.|last2=Ruble|first2=J. R.|last3=Yates|first3=J. H.|journal=Acta Crystallographica Section B: Structural Science|volume=39|issue=3|pages=388–394|bibcode=1983AcCrB..39..388J }}</ref>  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 pK<sub>a</sub> of 1,2,4-triazolium (C<sub>2</sub>N<sub>3</sub>H<sub>4</sub><sup>+</sup>) is 2.45.  The pK<sub>a</sub> of the neutral molecule is 10.26.<ref>{{cite book |doi=10.1016/B978-008096518-5.00080-0|chapter=1,2,4-Triazoles|title=Comprehensive Heterocyclic Chemistry II|year=1996|last1=Garratt|first1=Peter J.|pages=127–163|isbn=978-0-08-096518-5}}</ref>
==Synthesis and occurrence==
[[File:Fe(triazolate)3 (FIBCEA01).png|thumb|left|Portion of the structure of {[Fe(triazolate)(triazole)<sub>2</sub>](BF<sub>4</sub>)}<sub>n</sub>.<ref>{{cite journal |doi=10.1002/ejic.201201121|title=Crystal Structures and Spin Crossover in the Polymeric Material [Fe(HTRZ)2(TRZ)](BF4) Including Coherent-Domain Size Reduction Effects|year=2013|last1=Grosjean|first1=Arnaud|last2=Négrier|first2=Philippe|last3=Bordet|first3=Pierre|last4=Etrillard|first4=Céline|last5=Mondieig|first5=Denise|last6=Pechev|first6=Stanislav|last7=Lebraud|first7=Eric|last8=Létard|first8=Jean-François|last9=Guionneau|first9=Philippe|journal=European Journal of Inorganic Chemistry|volume=2013|issue=5–6|pages=796–802|url=https://hal.archives-ouvertes.fr/hal-00794417/file/GrosjeanEJIC2013_Postprint.pdf}}</ref>]]
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.<ref>{{cite journal |doi=10.15227/orgsyn.040.0099|author=C. Ainsworth|title=1,2,4-Triazole|journal=Organic Syntheses|year=1960|volume=40|pages=99}}</ref>
1,2,4-Triazoles are featured in many kinds of drugs.<ref>{{cite journal |doi=10.1111/cbdd.12527|title=Triazole: A Promising Antitubercular Agent|year=2015|last1=Keri|first1=Rangappa S.|last2=Patil|first2=Siddappa A.|last3=Budagumpi|first3=Srinivasa|last4=Nagaraja|first4=Bhari Mallanna|journal=Chemical Biology & Drug Design|volume=86|issue=4|pages=410–423|pmid=25643871|s2cid=9313180 }}</ref><ref>{{cite journal |doi=10.2174/1871520615666150819121106|title=Recent Developments on 1,2,4-Triazole Nucleus in Anticancer Compounds: A Review|year=2016|last1=Kaur|first1=Ramandeep|last2=Ranjan Dwivedi|first2=Ashish|last3=Kumar|first3=Bhupinder|last4=Kumar|first4=Vinod|journal=Anti-Cancer Agents in Medicinal Chemistry|volume=16|issue=4|pages=465–489|pmid=26286663}}</ref> Notable triazoles include the [[antifungal drug]]s [[fluconazole]] and [[itraconazole]]<ref>{{cite journal |doi=10.1016/j.bmc.2012.04.045|title=The biology and chemistry of antifungal agents: A review|year=2012|last1=Kathiravan|first1=Muthu K.|last2=Salake|first2=Amol B.|last3=Chothe|first3=Aparna S.|last4=Dudhe|first4=Prashik B.|last5=Watode|first5=Rahul P.|last6=Mukta|first6=Maheshwar S.|last7=Gadhwe|first7=Sandeep|journal=Bioorganic & Medicinal Chemistry|volume=20|issue=19|pages=5678–5698|pmid=22902032}}</ref> and the [[plant growth regulator]] [[paclobutrazol]].<ref>{{cite journal|title=A review on: Response of crops to paclobutrazol application|first=Wakjira|last=Tesfahun|editor-first=Fatih|editor-last=Yildiz|date=January 1, 2018|journal=Cogent Food & Agriculture|volume=4|issue=1|pages=1–9|doi=10.1080/23311932.2018.1525169|s2cid=134517280|doi-access=free|bibcode=2018CogFA...425169T }}</ref> Triazolate is a common [[bridging ligand]] in coordination chemistry.<ref>{{cite journal |doi=10.1016/S0010-8545(00)00266-6|title=Mononuclear, oligonuclear and polynuclear metal coordination compounds with 1,2,4-triazole derivatives as ligands|year=2000|last1=Haasnoot|first1=Jaap G.|journal=Coordination Chemistry Reviews|volume=200-202|pages=131–185}}</ref>
== References ==
{{Reflist}}
{{DEFAULTSORT:Triazole, 1, 2, 4-}}
[[Category:Triazoles]]