Benzimidazole


Benzimidazole is a heterocyclic aromatic organic compound. This bicyclic compound consists of the fusion of benzene and imidazole. It is a colorless solid.

Preparation

Benzimidazole is produced by condensation of o-phenylenediamine with formic acid, or the equivalent trimethyl orthoformate:
2-substituted derivatives are obtained when the condensation is conducted with aldehydes in place of formic acid, followed by oxidation. This method afford 2-substituted benzimidazoles.

Reactions

Benzimidazole is a base:
It can also be deprotonated with stronger bases:
The imine can be alkylated and also serves as a ligand in coordination chemistry. The most prominent benzimidazole complex features N-ribosyl-dimethylbenzimidazole as found in vitamin B12.
N,N'-Dialkylbenzimidazolium salts are precursors to certain N-heterocyclic carbenes.

Applications

Benzimidazoles are often bioactive. Many anthelmintic drugs belong to the benzimidazole class of compounds. Benzimidazole fungicides are commercialized. They act by binding to the fungal microtubules and stopping hyphal growth. It also binds to the spindle microtubules and blocks nuclear division.
with a benzimidazole core
The proton-pump inhibitors omeprazole, lansoprazole, pantoprazole, rabeprazole, and tenatoprazole all contain a benzimidazole group. Other pharmaceutical drugs which contain a benzimidazole group include etonitazene, galeterone, mavatrep, and dovitinib. Benzimidazole derivatives are among the top frequently used ring systems for small molecule drugs listed by the US FDA.
In printed circuit board manufacturing, benzimidazole can be used as an organic solderability preservative.
Several dyes are derived from benzimidazoles.