Benzimidazole

Benzimidazole
Names
Preferred IUPAC name
1H-1,3-Benzimidazole
Other names
1H-Benzo[d]imidazole
Identifiers
  • 51-17-2 Y
3D model (JSmol)
Beilstein Reference 109682
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.075
EC Number
  • 200-081-4
Gmelin Reference 3106
KEGG
UNII
CompTox Dashboard (EPA)
SMILES
  • c1ccc2c(c1)[nH]cn2
Properties
C7H6N2
Molar mass 118.14 g·mol−1
Melting point 170 to 172 °C (338 to 342 °F; 443 to 445 K)
Acidity (pKa) 12.8 (for benzimidazole) and 5.6 (for the conjugate acid)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references


Benzimidazole is an organic compound. It has the chemical formula C7H6N2. It is made of a benzene ring that shares a side with an imidazole ring. Like benzene and imidazole, it is an aromatic compound.

Chemicals that have the benzimidazole structure are called benzimidazoles. The chemical benzimidazole has few uses, but many benzimidazoles are used as drugs, plastics and dyes.

Examples and uses

Some examples of benzimidazoles:

  • Angiotensin II receptor blockers such as azilsartan, candesartan, and telmisartan.
  • Anthelmintic agents such as albendazole, ciclobendazole, fenbendazole, flubendazole, mebendazole, oxfendazole, oxibendazole, triclabendazole, and thiabendazole.
  • Antihistamines such as astemizole, bilastine, clemizole, emedastine, mizolastine, and oxatomide.
  • Benzimidazole fungicides such as benomyl, carbendazim, fuberidazole, and thiabendazole.
  • Nitazenes, or Benzimidazole opioids, such as bezitramide, brorphine, clonitazene, etodesnitazene, etonitazene, etonitazepipne, etonitazepyne, isotonitazene, metodesnitazene, and metonitazene.
  • Proton-pump inhibitors such as dexlansoprazole, esomeprazole, ilaprazole, lansoprazole, omeprazole, pantoprazole, rabeprazole, and tenatoprazole.
  • Typical antipsychotics such as benperidol, clopimozide, droperidol, neflumozide, and oxiperomide, and pimozide.
  • Benzimidazole can also be found in abemaciclib, bendamustine, dabigatran, daridorexant, and glasdegib.

When printed circuit boards are manufactured (or made), benzimidazole can be used as an organic solderability preservative. (When that kind of preservative gets used, it can protect copper contacts (for years), until the contact gets soldered.)

References

  1. Walba, Harold; Isensee, Robert W. (1961). "Acidity Constants of Some Arylimidazoles and Their Cations". The Journal of Organic Chemistry. 26 (8): 2789–2791. doi:10.1021/jo01066a039.