Benzimidazole

Benzimidazole

Names
Preferred IUPAC name 1H-Benzimidazole
Other names 1H-Benzo[d]imidazole
Identifiers
CAS Number	51-17-2 Y
3D model (Jmol)	Interactive image Interactive image
ChEBI	CHEBI:41275 Y
ChemSpider	5593 Y
ECHA InfoCard	100.000.075
KEGG	C02009 Y
PubChem CID	5798
UNII	E24GX49LD8 Y
InChI InChI=1S/C7H6N2/c1-2-4-7-6(3-1)8-5-9-7/h1-5H,(H,8,9) Y Key: HYZJCKYKOHLVJF-UHFFFAOYSA-N Y InChI=1/C7H6N2/c1-2-4-7-6(3-1)8-5-9-7/h1-5H,(H,8,9) Key: HYZJCKYKOHLVJF-UHFFFAOYAX
SMILES n2c1ccccc1nc2 c1ccc2c(c1)[nH]cn2
Properties
Chemical formula	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)
Hazards
Safety data sheet	External MSDS
EU classification (DSD)	Harmful (Xn)
R-phrases	R20 R21 R22 R36 R37 R38
S-phrases	S26 S36
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

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

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.

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.

Benzimidazoles are often bioactive. Many anthelmintic drugs (albendazole, mebendazole, triclabendazole etc.) 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.

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The benzimidazole opioid family includes a number of strong agents e.g. etonitazene, whose article discusses the family in some depth.

In printed circuit board manufacturing, benzimidazole can be used as a organic solderability preservative.