Benzimidazole is a heterocyclic aromatic
organic compoundAn organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered inorganic...
. This bicyclic compound consists of the fusion of
benzeneBenzene, or benzol, is an organic chemical compound with the molecular formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colorless and highly flammable liquid with a sweet smell and a relatively high melting point...
and
imidazoleImidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is classified as an alkaloid. Imidazole refers to the parent compound whereas imidazoles are a class of heterocycles with similar ring structure but varying substituents...
. The most prominent benzimidazole compound in nature is
N-ribosyl-dimethylbenzimidazole, which serves as an axial ligand for
cobaltCobalt is a hard, lustrous, gray metal, a chemical element with symbol Co and atomic number 27. Although cobalt-based colors and pigments have been used since ancient times for making jewelry and paints, and miners have long used the name kobold ore for some minerals, the free metallic cobalt was...
in
vitamin B12Cyanocobalamin is an especially common vitamer of the B-12 vitamin family. It is the most famous vitamer of the family, because it is chemically the most air-stable, and it is the easiest to crystallize and therefore easiest to purify after it is produced by bacterial fermentation. The cyanide is...
.
Benzimidazole, in an extension of the well-elaborated
imidazoleImidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is classified as an alkaloid. Imidazole refers to the parent compound whereas imidazoles are a class of heterocycles with similar ring structure but varying substituents...
system, has been used as carbon skeletons for N-heterocyclic carbenes.
Benzimidazole is a heterocyclic aromatic
organic compoundAn organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered inorganic...
. This bicyclic compound consists of the fusion of
benzeneBenzene, or benzol, is an organic chemical compound with the molecular formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colorless and highly flammable liquid with a sweet smell and a relatively high melting point...
and
imidazoleImidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is classified as an alkaloid. Imidazole refers to the parent compound whereas imidazoles are a class of heterocycles with similar ring structure but varying substituents...
. The most prominent benzimidazole compound in nature is
N-ribosyl-dimethylbenzimidazole, which serves as an axial ligand for
cobaltCobalt is a hard, lustrous, gray metal, a chemical element with symbol Co and atomic number 27. Although cobalt-based colors and pigments have been used since ancient times for making jewelry and paints, and miners have long used the name kobold ore for some minerals, the free metallic cobalt was...
in
vitamin B12Cyanocobalamin is an especially common vitamer of the B-12 vitamin family. It is the most famous vitamer of the family, because it is chemically the most air-stable, and it is the easiest to crystallize and therefore easiest to purify after it is produced by bacterial fermentation. The cyanide is...
.
Benzimidazole, in an extension of the well-elaborated
imidazoleImidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is classified as an alkaloid. Imidazole refers to the parent compound whereas imidazoles are a class of heterocycles with similar ring structure but varying substituents...
system, has been used as carbon skeletons for N-heterocyclic carbenes. The NHCs are usually used as
ligandIn chemistry, a ligand is either an atom, ion, or molecule that binds to a central metal-atom to produce a coordination complex. The bonding between the metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The metal-ligand bonding ranges from covalent...
s for transition metal complexes. They are often prepared by deprotonating an N,N'-disubstituted benzimidazolium salt at the 2-position with a base.
Preparation
Benzimidazole is commercially available. The usual synthesis involves condensation of
o-phenylenediamineo-Phenylenediamine is a chemical compound with the formula C6H42. This aromatic diamine is an important precursor to many heterocyclic compounds...
with
formic acidFormic acid is the simplest carboxylic acid. Its formula is HCOOH or CH2O2. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings.In nature, it is found in the stings and bites of many insects of the order...
, or the equivalent
trimethyl orthoformateOrthoformic acid is a hypothetical compound with the formula HC3. In this molecule, the central carbon is bound to one hydrogen and three hydroxyl groups. The compound cannot be isolated in substance as it would decompose into water and formic acid.While the free acid does not exist, its...
:
- C6H4(NH2)2 + HC(OCH3)3 → C6H4N(NH)CH + 3 CH3OH
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with formula CH3OH . It is toxic: drinking 10 ml will cause blindness, and as little as 100 ml will cause death...
By altering the carboxylic acid used, this method is generally able to afford 2-substituted benzimidazoles.
See also
- Benzimidazoline
Benzimidazolines are a family of heterocyclic compounds, based on a benzene ring fused with an imidazoline. The parent compound has the chemical formula C
7H
8N
2.- Benzimidazolines in dihydrogen storage :...
- Albendazole
Albendazole, marketed as Albenza, Eskazole, and Zentel, is a member of the benzimidazole compounds used as a drug indicated for the treatment of a variety of worm infestations. Although this use is widespread in the United States, the U.S. Food and Drug Administration has not approved albendazole...
, a common use anthelminticAnthelmintics or antihelminthics are drugs that expel parasitic worms from the body, by either stunning or killing them. They may also be called vermifuges or vermicides .-Pharmaceutical classes:...
.
- Indole
Indole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. Indole is a popular component of fragrances and the precursor to many pharmaceuticals. Compounds that contain an...
, an analog with CH in place of nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
in position 3.
- Purine
A purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines, including substituted purines and their tautomers, are the most widely distributed kind of nitrogen-containing heterocycle in nature....
, an analog with two additional nitrogen atomThe atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s in the six-membered ring.
- Simple aromatic ring
Simple aromatic rings, also known as simple arenes or simple aromatics, are aromatic organic compounds that consist only of a conjugated planar ring system with delocalized pi electron clouds. Many simple aromatic rings have trivial names. They are usually found as substructures of more complex...
s
- Triclabendazole
Triclabendazole is a member of the Benzimidazole family of anthelmintics...
, most common drug against liver flukeLiver flukes are a polyphyletic group of trematodes .Adults of liver flukes are localized in the liver of various mammals, including humans. These flatworms can occur in bile ducts, gallbladder, and liver parenchyma. They feed on blood...
s
- polybenzimidazole, a high performance fiber