Formic Acid → 7-Bromo-5-nitro-1H-benzimidazole

HRID 1622459Notes

Reaction equation

HRID 1622459 reaction equation
[Br:1][C:2]1[CH:7]=[C:6]([N+:8]([O-:10])=[O:9])[CH:5]=[C:4]([NH2:11])[C:3]=1[NH2:12].[CH:13](O)=O>C1(C)C=CC=CC=1>[Br:1][C:2]1[C:3]2[N:12]=[CH:13][NH:11][C:4]=2[CH:5]=[C:6]([N+:8]([O-:10])=[O:9])[CH:7]=1

Participants

4

Reactant 2

HCID 284Formic AcidHCID 203480123-Bromo-5-nitrobenzene-1,2-diamine

Product 1

HCID 532566897-Bromo-5-nitro-1H-benzimidazoleYield 96.2%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

To a 100 mL round bottomed flask was added 3-bromo-5-nitrobenzene-1,2-diamine (5 g, 21.55 mmol) and formic acid (3.25 mL, 86 mmol) in Toluene (10 mL). The solution was heated to reflux overnight. The product precipitated and was triturated with toluene, diluted with water and adjusted to ph 9 with 6N NaOH. The solid was filtered, washed with water and placed in a vacuum oven overnight to yield 4-bromo-6-nitro-1H-benzo[d]imidazole (5.02 g, 20.74 mmol, 96% yield) as a brown solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.16 (s, 1H) 8.29 (d, J=2.02 Hz, 1H) 8.51 (d, J=2.02 Hz, 1H) 8.66 (s, 1H); LC/MS: MS (ES+) m/e 243 [M+H]+.

Workup

  1. temperatureThe solution was heated
  2. temperatureto reflux overnight
  3. customThe product precipitated
  4. customwas triturated with toluene
  5. additiondiluted with water and adjusted to ph 9 with 6N NaOH
  6. filtrationThe solid was filtered
  7. washwashed with water
  8. customplaced in a vacuum oven overnight

Sources & evidence

ORD record
ord-d940db27c1db4e6cbcb8c0bfcece20e1
Source dataset
uspto-grants-2014_07
Patent number
US08778937B2

Reaction notes

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