Imidazole

Imidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is a diazole and one of the fundamental units of the vast class of histidine and histamine.

Structure and properties

Imidazole is a 5-membered planar ring, which is soluble in water and forms a tautomeric equilibrium. That is, the compound can be represented by two tautomeric chemical structures, the aromatic one being more stable than the open-chain form.

Preparation

Imidazole can be synthesized by numerous methods besides the Debus method. Many of these syntheses can also be applied to different substituted imidazoles.

Applications

Imidazole is incorporated into many important biological molecules. The most pervasive is the amino acid histidine, which has an imidazole side-chain. Many drugs contain an imidazole ring, such as certain antifungal drugs, the nitroimidazole series of antibiotics, and the sedative midazolam.

Safety

Imidazole is amphoteric, that is, it can function as both an acid and as a base. As an acid, the pKa of imidazole is 14.05, making it less acidic than carboxylic acids, phenols, and imides, but slightly more acidic than alcohols.

See also

• Pyrazole
• Pyrrole
• Oxazole
• Thiazole

References

• Resonance structures of imidazole
  Resonance structures of imidazole
• Imidazole synthesis from glyoxal, aldehyde, and ammonia
  Imidazole synthesis from glyoxal, aldehyde, and ammonia
• One-bond method for imidazole synthesis
  One-bond method for imidazole synthesis
• Two-bond method for imidazole synthesis
  Two-bond method for imidazole synthesis
• 
  (1,2)(3,4) formation of imidazole
• Debus-Radziszewski imidazole synthesis
  Debus-Radziszewski imidazole synthesis
• Imidazole synthesis from vinyltetrazole
  Imidazole synthesis from vinyltetrazole
• Imidazolium salt
  Imidazolium salt