Cas Number


Other Names


glyoxaline (archaic)


The formula



Imidazole is an organic compound. 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.

Physical and Chemical Properties
Appearance white or pale yellow solid
Molar mass 68.077 g/mol
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) [1]
UV-vis (λmax) 206 nm

1. Imidazole has been used extensively as a corrosion inhibitor on certain transition metals, such as copper. Preventing copper corrosion is important, especially in aqueous systems, where the conductivity of the copper decreases due to corrosion. Imidazoles can also be used as organic structure directing agents to synthesize zeollites.

2. Many compounds of industrial and technological importance contain imidazole derivatives. The thermostable polybenzimidazole (PBI) contains imidazole fused to a benzene ring and linked to a benzene, and acts as a fire retardant. Imidazole can also be found in various compounds that are used for photography and electronics.