Imidazole (ImH) is an organic compound with the formula C3N2H4. It is a white or colorless solid that is soluble in water to produce a slightly alkaline solution. Chemically, it is an aromatic heterocycle, classified as oxadiazoles, and has non-adjacent nitrogen atoms in the meta-substitution.

Many natural products, especially alkaloids, contain imidazole rings. These imidazoles share the 1,3-C3N2 ring but have different substituents. This ring system is present in important biological building blocks such as histidine and the related hormone histamine. Many drugs contain imidazole rings, such as certain antifungal drugs, nitroimidazole series antibiotics, and midazolam, which has a sedative effect. [4][5][6][7][8]

When fused to a pyrimidine ring, it forms a purine, the most ubiquitous nitrogen-containing heterocycle in nature. [9]

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