Benzimidazole

Structural formula
General
Surname	Benzimidazole
other names	1,3-benzodiazole 1 H -1,3-benzimidazole 1 H -Benzo [ d ] imidazole BENZIMIDAZOLE ( INCI )
Molecular formula	C 7 H 6 N 2
Brief description	colorless crystals
External identifiers / databases
CAS number 51-17-2 EC number 200-081-4 ECHA InfoCard 100,000,075 PubChem 5798 ChemSpider 5593 DrugBank DB02962 Wikidata Q415190
properties
Molar mass	118.14 g mol −1
Physical state	firmly
Melting point	171-174 ° C
boiling point	> 360 ° C
solubility	slightly soluble in water (2 g l −1 at 20 ° C) soluble in ethanol
safety instructions
GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
Toxicological data	2910 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Benzimidazole is a heterocyclic organic chemical compound that results from the fusion of benzene and imidazole . Compounds with this basic structure are called benzimidazoles , the most important representative of which in nature is the compound N-ribosyl-dimethylbenzimidazole, which occurs as a ligand for cobalt in vitamin B ₁₂ . But it is also related to purine and adenine , in which benzene is replaced by pyrimidine .

Extraction and presentation

Benzimidazole can be prepared by condensation of o-phenylenediamine with formic acid or the equivalent trimethyl orthoformate .

${\displaystyle \mathrm {C_{6}H_{4}(NH_{2})_{2}+HC(OCH_{3})_{3}\longrightarrow C_{6}H_{4}N(NH)CH+3\ CH_{3}OH} }$

use

Benzimidazole is used as a starting material for the production of derivatives derived therefrom. These are used as drugs (e.g. omeprazole , flubendazole , domperidone ), anthelmintics (ATC P02CA e.g. albendazole ), plastics (e.g. polybenzimidazole ) and dyes (e.g. benzimidazolone ).

They also serve as fungicides (MBC fungicides), the mechanism of action being based on the inhibition of cell division (mitosis) by destroying the building blocks of the spindle apparatus. Since this is only one point of attack in the fungus's metabolism, there is therefore a high risk of resistance. This group includes, among other things, active ingredients with an effect against strawberries and snow mold . They have a healing (curative) but no preventive (protective) effect. Some of these derivatives are:

• Carbendazim (e.g. Harvesan fungicide and seed dressings)
• Thiophanate methyl (e.g. cercobin)
• Fuberidazole (e.g. in seed dressings)
• Benomyl (no longer approved)
• Fenbendazole
• Mebendazole
• Thiabendazole

Carbendazim is the actual active ingredient and thiophanate-methyl and benomyl are converted to carbendazim in the plant. Compounds such as netobimin and febantel, which as such do not contain a benzimidazole structure, but which are formed from the substances in the organism, are referred to as sample zimidazoles .

Individual evidence

1. ↑ Entry on BENZIMIDAZOLE in the CosIng database of the EU Commission, accessed on May 12, 2020.
2. ↑ Entry on benzimidazole. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
3. ↑ ^{a b c d e f} sheet benzimidazole (PDF) at Merck , retrieved on December 27, 2019 .
4. ↑ ^{a b} Entry on benzimidazole in the ChemIDplus database of the United States National Library of Medicine (NLM) .
5. ^ EC Wagner and WH Millett: Benzimidazole In: Organic Syntheses . 19, 1939, p. 12, doi : 10.15227 / orgsyn.019.0012 ; Coll. Vol. 2, 1943, p. 65 ( PDF ).
6. ↑ Antiparasitics (Austrian Agency for Health and Food Safety) ( Memento from April 25, 2014 in the Internet Archive ).