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File:Benzimidazole chemical structure.png
style="background: #F8EABA; text-align: center;" colspan="2" | Identifiers
CAS number 51-17-2 YesY
PubChem 5798
ChemSpider 5593
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InChI Script error: No such module "collapsible list".
style="background: #F8EABA; text-align: center;" colspan="2" | Properties
Molecular formula C7H6N2
Molar mass 118.14 g mol−1
Melting point

170–172 °C

style="background: #F8EABA; text-align: center;" colspan="2" | Hazards
MSDS External MSDS
EU classification Harmful (Xn)
R-phrases R20 R21 R22 R36 R37 R38
S-phrases S26 S36
 YesY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Benzimidazole is a heterocyclic aromatic organic compound. This bicyclic compound consists of the fusion of benzene and imidazole. The most prominent benzimidazole compound in nature is N-ribosyl-dimethylbenzimidazole, which serves as an axial ligand for cobalt in vitamin B12.[1]

Benzimidazole, in an extension of the well-elaborated imidazole system, has been used as carbon skeletons for N-heterocyclic carbenes. The NHCs are usually used as ligands for transition metal complexes. They are often prepared by deprotonating an N,N'-disubstituted benzimidazolium salt at the 2-position with a base.[2][3]


Benzimidazole is commercially available. The usual synthesis involves condensation of o-phenylenediamine with formic acid,[4] or the equivalent trimethyl orthoformate:

C6H4(NH2)2 + HC(OCH3)3 → C6H4N(NH)CH + 3 CH3OH

By altering the carboxylic acid used, this method is generally able to afford 2-substituted benzimidazoles.[4] Benzimidazole also has fungicidal properties. It acts by binding to the fungal microtubules and stopping hyphal growth. It also binds to the spindle microtubules and blocks nuclear division.

See also


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Further reading

  • Grimmett, M. R. (1997). Imidazole and benzimidazole synthesis. Boston: Academic Press. ISBN 0-12-303190-7. 

cs:Benzimidazoly de:Benzimidazol es:Benzimidazol ja:ベンゾイミダゾール pl:Benzimidazol pt:Benzimidazol ru:Бензимидазол th:เบนซิมิดาโซล

  1. H. A. Barker, R. D. Smyth, H. Weissbach, J. I. Toohey, J. N. Ladd, and B. E. Volcani (February 1, 1960). "Isolation and Properties of Crystalline Cobamide Coenzymes Containing Benzimidazole or 5,6-Dimethylbenzimidazole". Journal of Biological Chemistry. 235 (2): 480–488. PMID 13796809. 
  2. R. Jackstell, A. Frisch, M. Beller, D. Rottger, M. Malaun and B. Bildstein (2002). "Efficient telomerization of 1,3-butadiene with alcohols in the presence of in situ generated palladium(0)carbene complexes". Journal of Molecular Catalysis A: Chemical. 185 (1-2): 105–112. doi:10.1016/S1381-1169(02)00068-7. 
  3. H. V. Huynh, J. H. H. Ho, T. C. Neo and L. L. Koh (2005). "Solvent-controlled selective synthesis of a trans-configured benzimidazoline-2-ylidene palladium(II) complex and investigations of its Heck-type catalytic activity". Journal of Organometallic Chemistry. 690 (16): 3854–3860. doi:10.1016/j.jorganchem.2005.04.053. 
  4. 4.0 4.1 E. C. Wagner and W. H. Millett (1943), "Benzimidazole", Org. Synth. ; Coll. Vol., 2: 65  Missing or empty |title= (help)