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 B. 12 [2 ]
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. [3 ] [4 ]
Preparation [ edit ]
Benzimidazole is commercially available. The usual synthesis involves condensation of
o-phenylenediamine with formic acid, or the equivalent [5 ] trimethyl orthoformate:
6H 4(NH 2) 2 + HC(OCH 3) 3 → C 6H 4N(NH)CH + 3 CH 3OH
By altering the carboxylic acid used, this method is generally able to afford 2-substituted benzimidazoles.
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. [5 ]
See also [ edit ]
References [ edit ]
^ Walba, H. & Isensee, R. W. Acidity constants of some arylimidazoles and their cations. J. Org. Chem. 26, 2789-2791 (1961).
^ 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.
^ 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.
^ 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.
^ a b E. C. Wagner and W. H. Millett (1943), "Benzimidazole", Org. Synth. ; Coll. Vol. 2: 65 .
Further reading [ edit ]
Grimmett, M. R. (1997). Imidazole and benzimidazole synthesis. Boston: Academic Press. ISBN 0-12-303190-7.