Imidazole
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| Names | |||
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IUPAC name
1H-Imidazole
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| Other names
1,3-diazole
glyoxaline (archaic) 1,3-diazacyclopenta-2,4-diene |
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| Identifiers | |||
288-32-4 
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| 3D model (Jmol) | Interactive image | ||
| ChEBI |
CHEBI:16069
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| ChEMBL |
ChEMBL540
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| ChemSpider |
773
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| ECHA InfoCard | 100.005.473 | ||
| EC Number | 206-019-2 | ||
| KEGG |
C01589
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| PubChem | 795 | ||
| RTECS number | NI3325000 | ||
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| Properties | |||
| 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) | ||
| Soluble | |||
| Acidity (pKa) | 14.5 (for imidazole) and 7.05 (for the conjugate acid) | ||
| UV-vis (λmax) | 280 nm | ||
| Structure | |||
| monoclinic | |||
| planar 5-membered ring | |||
| 3.61 D | |||
| Hazards | |||
| Main hazards | Corrosive | ||
| Safety data sheet | External MSDS | ||
| R-phrases | R20 R22 R34 R41 | ||
| S-phrases | S26 S36 S37 S39 S45 | ||
| Flash point | 146 °C (295 °F; 419 K) | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is  ?) |
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| Infobox references | |||
Imidazole 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 having non-adjacent nitrogen atoms.
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.
When fused to a pyrimidine ring, it forms purine, which is the most widely occurring nitrogen-containing heterocycle in nature.
The name "imidazole" was coined in 1887 by the German chemist Arthur Rudolf Hantzsch (1857–1935).
Imidazole is a planar 5-membered ring. It exists in two equivalent tautomeric forms, because the positive charge can be located on either of the two nitrogen atoms. Imidazole is a highly polar compound, as evidenced by its electric dipole moment of 3.67 D. It is highly soluble in water. The compound is classified as aromatic due to the presence of a sextet of π-electrons, consisting of a pair of electrons from the protonated nitrogen atom and one from each of the remaining four atoms of the ring. Some resonance structures of imidazole are shown below:
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Wikipedia