Benzimidazole

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Names
Preferred IUPAC name

1H-1,3-Benzimidazole

Other names

1H-Benzo[d]imidazole

Identifiers

CAS Number

* 51-17-2 Y

3D model (JSmol)

* Interactive image

Beilstein Reference

| 109682
ChEBI |

* CHEBI:41275 Y

ChEMBL |

* ChEMBL306226 Y

ChemSpider |

* 5593 Y

DrugBank |

* DB02962

EC Number |

* 200-081-4

Gmelin Reference

| 3106
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

* c1ccc2c(c1)[nH]cn2

Properties

Chemical formula

| C7H6N2
Molar mass | 118.139 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]
Hazards
Safety data sheet | External MSDS
GHS pictograms |
GHS Signal word | Warning

GHS hazard statements

| H302, H315, H319, H335

GHS precautionary statements

| P261, P264, P270, P271, P280, P301+312, P302+352, P304+340, P305+351+338, P312, P321, P330, P332+313, P337+313, P362, P403+233, P405, P501

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Y verify (what is YN ?)
Infobox references

Tracking categories (test):

* SizeSet
* PairSizeSet

Benzimidazole is a heterocyclic aromatic organic compound. This bicyclic compound may be viewed as fused rings of the aromatic compounds benzene and imidazole. It is a white solid that appears in form of tabular crystals.[2]

## Contents

* 1 Preparation
* 2 Reactions
* 3 Applications
* 4 See also
* 5 References
* 6 Further reading

## Preparation

Benzimidazole is produced by condensation of o-phenylenediamine with formic acid,[3]

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

2-Substituted derivatives are obtained when the condensation is conducted with aldehydes in place of formic acid, followed by oxidation.[4]

## Reactions

Benzimidazole is a base:

C6H4N(NH)CH + H+ → [C6H4(NH)2CH]+

It can also be deprotonated with stronger bases:

C6H4N(NH)CH + LiH → Li [C6H4N2CH] + H2

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.[5]

N,N'-Dialkylbenzimidazolium salts are precursors to certain N-heterocyclic carbenes.[6][7]

## Applications

Benomyl is a fungicide with a benzimidazole core

Benzimidazole derivatives are among the most frequently used ring systems for small molecule drugs listed by the United States Food and Drug Administration.[8] Many pharmaceutical agents belong to the benzimidazole class of compounds. For example:

* 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.
* 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.
* Other notable pharmaceutical agents which contain a benzimidazole group include abemaciclib, bendamustine, dabigatran, daridorexant, and glasdegib.

In printed circuit board manufacturing, benzimidazole can be used as an organic solderability preservative.[citation needed]

Several dyes are derived from benzimidazoles.[9]

## See also

* Benzimidazoline
* Polybenzimidazole, a high performance fiber

## 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.
2. ↑ "Benzimidazole | CAMEO Chemicals | NOAA". https://cameochemicals.noaa.gov/chemical/19860#:~:text=white,crystals.
3. ↑ E. C. Wagner, W. H. Millett (1939). "Benzimidazole". Organic Syntheses 19: 12. doi:10.15227/orgsyn.019.0012.
4. ↑ Robert A. Smiley "Phenylene- and Toluenediamines" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_405
5. ↑ H. A. Barker; R. D. Smyth; H. Weissbach; J. I. Toohey; J. N. Ladd; 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. doi:10.1016/S0021-9258(18)69550-X. PMID 13796809.
6. ↑ R. Jackstell; A. Frisch; M. Beller; D. Rottger; M. Malaun; 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.
7. ↑ H. V. Huynh; J. H. H. Ho; T. C. Neo; 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.
8. ↑ Taylor, R. D.; MacCoss, M.; Lawson, A. D. G. J Med Chem 2014, 57, 5845.>
9. ↑ Horst Berneth "Methine Dyes and Pigments" in Ullmann's Encyclopedia of Industrial Chemistry, 2008, Wiley-VCH, Weinheim. doi: 10.1002/14356007.a16_487.pub2

## Further reading

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

* v
* t
* e

Antiparasitics – Anthelmintics (P02) and Endectocides (QP54)

Antiplatyhelmintic agents|

| Antitrematodals
(schistosomicides)|

| Binds tubulin|

* benzimidazole
* Triclabendazole#

|

AI|

* phosphonic acid
* Metrifonate‡

Other/unknown|

* quinoline
* Praziquantel#
* Oxamniquine#
* phenol
* Bithionol
* thiazole
* Niridazole
* arylsulfonate
* Stibophen

Anticestodals
(taeniacides)|

| Binds tubulin|

* benzimidazole
* Albendazole#

|

Other/unknown|

* quinoline
* Praziquantel#
* salicylanilide
* Niclosamide#
* aminoacridine
* Quinacrine
* butyrophenone
* Desaspidin
* chlorophenol
* Dichlorophen

Antinematodal agents
(including
macrofilaricides)|

| Binds tubulin|

* benzimidazole
* Mebendazole#
* Albendazole#
* Tiabendazole
* Fenbendazole
* Ciclobendazole
* Flubendazole

|

Glutamate-gated chloride channel, GABA receptor|

* avermectins
* Abamectin
* Doramectin
* Emamectin
* Ivermectin#
* Selamectin
* milbemycins
* Moxidectin
* Milbemycin oxime

NMDA|

* tetrahydropyrimidine
* Pyrantel#
* pyrantel pamoate
* Oxantel
* Morantel
* Carbantel
* Febantel (aka felsantel)

Other/unknown|

* piperazine
* Piperazine
* Diethylcarbamazine#
* thiazole
* Levamisole#
* quinolinium
* Pyrvinium
* benzylammonium
* Bephenium
* naphthalenesulfonate
* Suramin#
* Tribendimidine

* #WHO-EM
* ‡Withdrawn from market
* Clinical trials:
* †Phase III
* §Never to phase III

* v
* t
* e

Antiparasitics – antiprotozoal agents – Excavata antiparasitics (P01)

Discicristata|

| Trypanosomiasis|

* African trypanosomiasis: ornithine]] (Eflornithine#)
* arsenical (Melarsoprol#)
* benzamidine (Pentamidine#)
* naphthalenesulfonate (Suramin#)

* nitroimidazole (Fexinidazole†)

Chagas disease: nitroimidazole]] (Benznidazole#)

* nitrofuran (Nifurtimox#)

|

Leishmaniasis|

* macrolide (Amphotericin B#)

Pentavalent antimonials (Meglumine antimoniate#, Sodium stibogluconate)

* benzamidine (Pentamidine#)
* phosphorylcholine (Miltefosine)
* neomycin (Paromomycin)

PAM|

* macrolide (Amphotericin B)

Trichozoa|

| Giardiasis|

* nitroimidazole (Metronidazole#, Tinidazole)
* benzimidazole (Albendazole)

* thiazolide (Nitazoxanide)
* nitrofuran (Furazolidone)

* aminoacridine (Quinacrine)

|

Trichomoniasis|

* nitroimidazole (Carnidazole, Metronidazole#, Tinidazole)

Dientamoebiasis|

* nitroimidazole (Metronidazole
* Secnidazole)

* oxyquinoline (Iodoquinol)
* tetracycline (Doxycycline)
* neomycin (Paromomycin)

* #WHO-EM
* ‡Withdrawn from market
* Clinical trials:
* †Phase III
* §Never to phase III

* v
* t
* e

Antifungals (D01 and J02)

Wall/
membrane|

| Ergosterol
inhibitors|

| Azoles (lanosterol 14α-
demethylase inhibitors)|

| Imidazoles|

* Topical: bifonazole‡
* butoconazole
* chlormidazole‡
* clotrimazole#
* croconazole‡
* eberconazole
* econazole
* fenticonazole‡
* flutrimazole
* isoconazole
* ketoconazole
* luliconazole
* miconazole#
* neticonazole‡
* omoconazole‡
* oxiconazole
* sertaconazole
* sulconazole
* tioconazole

* Systemic: ketoconazole

|

Triazoles|

* Topical: efinaconazole
* fluconazole#
* terconazole

* Systemic: fluconazole#
* hexaconazole‡
* fosfluconazole
* isavuconazole
* itraconazole
* posaconazole
* voriconazole

* Unknown: albaconazole‡
* ravuconazole†

Thiazoles|

* Topical: abafungin‡

Polyene antimycotics
(ergosterol binding)|

* Topical: hamycin‡
* natamycin
* nystatin#
Systemic: amphotericin B#, hamycin‡

Squalene monooxygenase
inhibitors|

| Allylamines|

* Topical: naftifine
* terbinafine
Systemic: terbinafine

|

Benzylamines|

* Topical: butenafine

Others|

* Topical: amorolfine

β-glucan synthase
inhibitors|

* Systemic: echinocandins (anidulafungin
* biafungin
* caspofungin
* cilofungin
* micafungin)

Intracellular|

| Pyrimidine analogues/
thymidylate synthase inhibitors|

* Systemic: flucytosine#

|

Mitotic inhibitors|

* Systemic: griseofulvin#

Aminoacyl tRNA synthetase inhibitors|

* Topical: tavaborole

Others|

* bromochlorosalicylanilide
* chlorophetanol
* chlorphenesin
* ciclopirox
* crystal violet
* dimazole
* ethylparaben
* haloprogin‡
* polynoxylin
* potassium iodide#
* salicylic acid
* selenium disulfide#
* sodium thiosulfate#
* sulbentine
* taurolidine
* ticlatone
* tolciclate
* tolnaftate
* tribromometacresol
* undecylenic acid
* Whitfield's ointment#

* citronella oil
* lemon grass
* lemon myrtle
* orange oil
* patchouli
* tea tree oil
* PCP: atovaquone
* dapsone
* pentamidine

* #WHO-EM
* ‡Withdrawn from market
* Clinical trials:
* †Phase III
* §Never to phase III

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Original source: https://en.wikipedia.org/wiki/Benzimidazole. Read more

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Retrieved from "https://handwiki.org/wiki/index.php?title=Chemistry:Benzimidazole&oldid=2778973"
*[CID]: Compound ID
*[H302]: Harmful if swallowed
*[H315]: Causes skin irritation
*[H319]: Causes serious eye irritation
*[H335]: May cause respiratory irritation
*[P261]: Avoid breathing dust/fume/gas/mist/vapours/spray
*[P264]: Wash … thoroughly after handling
*[P270]: Do not eat, drink or smoke when using this product
*[P271]: Use only outdoors or in a well-ventilated area
*[P280]: Wear protective gloves/protective clothing/eye protection/face protection
*[P301+312]: IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell
*[P302+352]: IF ON SKIN: Wash with soap and water
*[P304+340]: IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing
*[P305+351+338]: IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do – continue rinsing
*[P312]: Call a POISON CENTER or doctor/physician if you feel unwell
*[P321]: Specific treatment (see … on this label)
*[P330]: Rinse mouth
*[P332+313]: If skin irritation occurs: Get medical advice/attention
*[P337+313]: Get medical advice/attention
*[P362]: Take off contaminated clothing and wash before reuse
*[P403+233]: Store in a well ventilated place. Keep container tightly closed
*[P405]: Store locked up
*[P501]: Dispose of contents/container to …
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