Imidazole

Imidazole
Names
	Preferred IUPAC name 1H-Imidazole
	Other names 1,3-Diazole; Glyoxaline (archaic)
Identifiers
CAS Number	288-32-4 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	103853
ChEBI	CHEBI:16069 ;
ChEMBL	ChEMBL540 ;
ChemSpider	773 ;
DrugBank	DB03366;
ECHA InfoCard	100.005.473
EC Number	206-019-2;
Gmelin Reference	1417
KEGG	C01589 ;
PubChem CID	795;
RTECS number	NI3325000;
UNII	7GBN705NH1 ;
UN number	3263
CompTox Dashboard (EPA)	DTXSID2029616 ;
	InChI InChI=1S/C3H4N2/c1-2-5-3-4-1/h1-3H,(H,4,5) Key: RAXXELZNTBOGNW-UHFFFAOYSA-N ; InChI=1/C3H4N2/c1-2-5-3-4-1/h1-3H,(H,4,5);
	SMILES c1cnc[nH]1;
Properties
Chemical formula	C3H4N2
Molar mass	68.077 g/mol
Appearance	White or pale yellow solid
Density	1.23 g/cm3, solid
Melting point	89 to 91 °C (192 to 196 °F; 362 to 364 K)
Boiling point	256 °C (493 °F; 529 K)
Solubility in water	633 g/L
Acidity (pKa)	6.95 (for the conjugate acid)
UV-vis (λmax)	206 nm
Structure
Crystal structure	Monoclinic
Coordination geometry	Planar 5-membered ring
Dipole moment	3.61 D
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Corrosive
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H314, H360D
Precautionary statements	P263, P270, P280, P301+P310, P305+P351+P338, P308+P313
Flash point	146 °C (295 °F; 419 K)
Safety data sheet (SDS)	External MSDS
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Imidazole (ImH) is an organic compound with the formula C₃N₂H₄. It is a white or colourless solid that is soluble in water, producing a mildly alkaline solution. In chemistry, it is an aromatic heterocycle, classified as a diazole, and has non-adjacent nitrogen atoms in meta-substitution.

Many natural products, especially alkaloids, contain the imidazole ring. These imidazoles share the 1,3-C₃N₂ ring but feature varied substituents. This ring system is present in important biological building blocks, such as histidine and the related hormone histamine. Many drugs contain an imidazole ring, such as certain antifungal drugs, the nitroimidazole series of antibiotics, and the sedative midazolam.^[5]^[6]^[7]^[8]^[9]

When fused to a pyrimidine ring, it forms a purine, which is the most widely occurring nitrogen-containing heterocycle in nature.^[10]

The name "imidazole" was coined in 1887 by the German chemist Arthur Rudolf Hantzsch (1857–1935).^[11]

^ "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 140. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
^ Walba, H.; Isensee, R. W. (1961). "Acidity constants of some arylimidazoles and their cations". J. Org. Chem. 26 (8): 2789–2791. doi:10.1021/jo01066a039.
^ "Imidazole". molekula.com. Molekula Group. Archived from the original on 2018-10-19. Retrieved 2018-10-19.
^ "Imidazole". pubchem.ncbi.nlm.nih.gov. Archived from the original on 10 May 2023. Retrieved 17 February 2024.
^ Karitzky, A. R.; Rees, C.W.R.; Scriven, E.F.V. (1984). Comprehensive Heterocyclic Chemistry. Vol. 5. pp. 469–498. ISBN 978-0-08-042072-1.
^ Grimmett, M. Ross (1997). Imidazole and Benzimidazole Synthesis. Academic Press. ISBN 978-0-08-053445-9.
^ Brown, E. G. (1998). Ring Nitrogen and Key Biomolecules. Kluwer Academic Press. ISBN 978-94-011-4906-8.
^ Pozharskii, A. F.; et al. (1997). Heterocycles in Life and Society. John Wiley & Sons. ISBN 978-0-471-96033-1.
^ Gilchrist, T. L. (1985). Heterocyclic Chemistry. Bath Press. ISBN 978-0-582-01421-3.
^ Rosemeyer, H. (2004). "The Chemodiversity of Purine as a Constituent of Natural Products". Chemistry & Biodiversity. 1 (3): 361–401. doi:10.1002/cbdv.200490033. PMID 17191854. S2CID 12416667.
^ Hantzsch, A. and Weber, J. H. (1887) "Ueber Verbindungen des Thiazols (Pyridins der Thiophenreihe)" Archived 2020-05-30 at the Wayback Machine (On compounds of thiazole (pyridines of the thiophene series), Berichte der deutschen chemischen Gesellschaft, 20 : 3118–3132, see p. 3119. See also: Hantzsch, A. (1888) "Allegemeine Bemerkungen über Azole" Archived 2020-05-30 at the Wayback Machine (General observations about azoles), Annalen der Chemie, 249 : 1–6. Hantzsch proposed a reform of the nomenclature of azole compounds, including a proposal to call the heterocyclic ring C₃H₃(NH)N "imidazole" ; see pp. 2 and 4.

[iupac2013-1] "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 140. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.

[2] Walba, H.; Isensee, R. W. (1961). "Acidity constants of some arylimidazoles and their cations". J. Org. Chem. 26 (8): 2789–2791. doi:10.1021/jo01066a039.

[3] "Imidazole". molekula.com. Molekula Group. Archived from the original on 2018-10-19. Retrieved 2018-10-19.

[4] "Imidazole". pubchem.ncbi.nlm.nih.gov. Archived from the original on 10 May 2023. Retrieved 17 February 2024.

[5] Karitzky, A. R.; Rees, C.W.R.; Scriven, E.F.V. (1984). Comprehensive Heterocyclic Chemistry. Vol. 5. pp. 469–498. ISBN 978-0-08-042072-1.

[6] Grimmett, M. Ross (1997). Imidazole and Benzimidazole Synthesis. Academic Press. ISBN 978-0-08-053445-9.

[7] Brown, E. G. (1998). Ring Nitrogen and Key Biomolecules. Kluwer Academic Press. ISBN 978-94-011-4906-8.

[8] Pozharskii, A. F.; et al. (1997). Heterocycles in Life and Society. John Wiley & Sons. ISBN 978-0-471-96033-1.

[9] Gilchrist, T. L. (1985). Heterocyclic Chemistry. Bath Press. ISBN 978-0-582-01421-3.

[10] Rosemeyer, H. (2004). "The Chemodiversity of Purine as a Constituent of Natural Products". Chemistry & Biodiversity. 1 (3): 361–401. doi:10.1002/cbdv.200490033. PMID 17191854. S2CID 12416667.

[11] Hantzsch, A. and Weber, J. H. (1887) "Ueber Verbindungen des Thiazols (Pyridins der Thiophenreihe)" Archived 2020-05-30 at the Wayback Machine (On compounds of thiazole (pyridines of the thiophene series), Berichte der deutschen chemischen Gesellschaft, 20 : 3118–3132, see p. 3119. See also: Hantzsch, A. (1888) "Allegemeine Bemerkungen über Azole" Archived 2020-05-30 at the Wayback Machine (General observations about azoles), Annalen der Chemie, 249 : 1–6. Hantzsch proposed a reform of the nomenclature of azole compounds, including a proposal to call the heterocyclic ring C₃H₃(NH)N "imidazole" ; see pp. 2 and 4.

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