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5-Nitroimidazole is an organic compound with the formula O2NC3H2N2H. The nitro group at position 5 on the imidazole ring is the most common positional isomer. The term nitroimidazole also refers to a class of antibiotics that share similar chemical structures.[2]

IUPAC name
3D model (JSmol)
Molar mass 113.07 g/mol
Melting point 303 °C (577 °F; 576 K) (decomposes)
Main hazards Xn
R-phrases (outdated) R20/21/22 R36/37/38
S-phrases (outdated) S26 S36/37
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references


Imidazole reacts with a mixture of nitric acid to give 5-nitroimidazole:

C3H3N2H + HNO3 → O2NC3H2N2H + H2O

Under conventional conditions for nitration, the reaction is conducted in the presence of sulfuric acid.

Nitroimidazole antibioticsEdit

Position numbers on the ring

From the chemistry perspective, nitroimidazole antibiotics can be classified according to the location of the nitro functional group. 4- and 5-nitroimidazole are equivalent from the perspective of drugs since these tautomers readily interconvert. Drugs of the 5-nitro variety include metronidazole, tinidazole, nimorazole, dimetridazole, 6-Amino PA824, ornidazole, megazol, and azanidazole. Drugs based on 2-nitromidazoles include benznidazole.

Nitroimidazole antibiotics have been used to combat anaerobic bacterial and parasitic infections.[3] Perhaps the most common example is metronidazole. Other heterocycles such as nitrothiazoles (thiazole) are also used for this purpose. Nitroheterocycles may be reductively activated in hypoxic cells, and then undergo redox recycling or decompose to toxic products.[4]

Three nitroimidazoles: metronidazole, tinidazole, and nimorazole


  1. ^ 4-Nitroimidazole at Sigma-Aldrich
  2. ^ Edwards, David I. "Nitroimidazole drugs - action and resistance mechanisms. I. Mechanism of action" Journal of Antimicrobial Chemotherapy 1993, volume 31, pp. 9-20. doi:10.1093/jac/31.1.9.
  3. ^ Mital A (2009). "Synthetic Nitroimidazoles: Biological Activities and Mutagenicity Relationships". Sci Pharm. 77 (3): 497–520. doi:10.3797/scipharm.0907-14. 
  4. ^ Juchau, MR (1989). "Bioactivation in chemical teratogenesis". Annu. Rev. Pharmacol. Toxicol. 29: 165–167. doi:10.1146/ PMID 2658769.