indazole

{{Chembox

| ImageFile_Ref = {{chemboximage|correct|??}}

| ImageFile = Indazole 2D numbered.svg

| ImageSize = 170

| ImageAlt = Skeletal formula with numbering convention

| ImageFileL1 = Indazole 3D ball.png

| ImageAltL1 = Ball-and-stick model

| ImageFileR1 = Indazole 3D spacefill.png

| ImageAltR1 = Space-filling model

| PIN = 1H-Indazole{{cite book |author=International Union of Pure and Applied Chemistry |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=The Royal Society of Chemistry |pages=213 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}

| OtherNames =

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 8866

| InChI = 1/C7H6N2/c1-2-4-7-6(3-1)5-8-9-7/h1-5H,(H,8,9)

| InChIKey = BAXOFTOLAUCFNW-UHFFFAOYAQ

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 86795

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/C7H6N2/c1-2-4-7-6(3-1)5-8-9-7/h1-5H,(H,8,9)

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = BAXOFTOLAUCFNW-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 271-44-3

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 7C4VQE5C03

| PubChem = 9221

| ChEBI_Ref = {{ebicite|correct|EBI}}

| ChEBI = 36670

| SMILES = c2ccc1[nH]ncc1c2

}}

|Section2={{Chembox Properties

| Formula = C₇H₆N₂

| MolarMass = 118.14 g/mol

| Appearance =

| Density =

| MeltingPtC = 147 to 149

| MeltingPt_notes =

| BoilingPtC = 270

| Solubility =

}}

|Section3={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

}}

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Indazole, also called isoindazole, is a heterocyclic aromatic organic compound. This bicyclic compound consists of the fusion of benzene and pyrazole.

Indazole is an amphoteric molecule which can be protonated to an indazolium cation or deprotonated to an indazolate anion. The corresponding pKa values are 1.04 for the equilibrium between indazolium cation and indazole and 13.86 for the equilibrium between indazole and indazolate anion.{{Cite book |last1=Catalan |first1=Javier |title=Advances in Heterocyclic Chemistry Volume 41 |date=1987 |doi=10.1016/s0065-2725(08)60162-2 |volume=41 |pages=187–274 |publisher=Elsevier |last2=Elguero |first2=Jose |chapter=Basicity and Acidity of Azoles |isbn=9780120206414 }}

Indazole derivatives display a broad variety of biological activities.

Indazoles are rare in nature. The alkaloids nigellicine, nigeglanine, and nigellidine are indazoles. Nigellicine was isolated from the widely distributed plant Nigella sativa L. (black cumin). Nigeglanine was isolated from extracts of Nigella glandulifera.

The Davis–Beirut reaction can generate 2H-indazoles.{{cite journal |last1=Zhu |first1=Jie S. |last2=Haddadin |first2=Makhluf J. |last3=Kurth |first3=Mark J. |title=Davis–Beirut Reaction: Diverse Chemistries of Highly Reactive Nitroso Intermediates in Heterocycle Synthesis |journal=Accounts of Chemical Research |date=22 July 2019 |volume=52 |issue=8 |pages=2256–2265 |doi=10.1021/acs.accounts.9b00220|pmid=31328502 |pmc=6702092 }}

Indazole, C₇H₆N₂, was obtained by E. Fischer (Ann. 1883, 221,

p. 280) by heating ortho-hydrazine cinnamic acid,{{cite EB1911 |wstitle=Indazoles |volume=14 |page=371}}

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