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Skeletal formula with numbering convention
Ball-and-stick model
Space-filling model
Preferred IUPAC name
3D model (JSmol)
ECHA InfoCard 100.005.436 Edit this at Wikidata
  • InChI=1S/C7H6N2/c1-2-4-7-6(3-1)5-8-9-7/h1-5H,(H,8,9) checkY
  • InChI=1/C7H6N2/c1-2-4-7-6(3-1)5-8-9-7/h1-5H,(H,8,9)
  • c2ccc1[nH]ncc1c2
Molar mass 118.14 g/mol
Melting point 147 to 149 °C (297 to 300 °F; 420 to 422 K)
Boiling point 270 °C (518 °F; 543 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.[2]

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.

Indazole, C7H6N2, was obtained by E. Fischer (Ann. 1883, 221, p. 280) by heating ortho-hydrazine cinnamic acid,[3]

Fischer indazole.png

Some derivatives[edit]

indazole-3-carboxylic acid
Having a carboxylic acid group on carbon 3. Can be further modified to lonidamine.

See also[edit]


  1. ^ International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 213. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
  2. ^ Catalan, Javier; Elguero, Jose (1987), "Basicity and Acidity of Azoles", Advances in Heterocyclic Chemistry Volume 41, Elsevier, pp. 187–274, retrieved 2022-08-30
  3. ^ Chisholm, Hugh, ed. (1911). "Indazoles" . Encyclopædia Britannica. Vol. 14 (11th ed.). Cambridge University Press. p. 371.
  • Synthesis: W. Stadlbauer, in Science of Synthesis 2002, 12, 227, and W. Stadlbauer, in Houben-Weyl, 1994, E8b, 764.
  • Review: A. Schmidt, A. Beutler, B. Snovydovych, Recent Advances in the Chemistry of Indazoles, Eur. J. Org. Chem. 2008, 4073 – 4095.