Formic Acid → 4-Bromo-1H-benzimidazole

Reaction equation

[Br:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([NH2:8])[C:3]=1[NH2:9].[CH:10](O)=O>>[Br:1][C:2]1[C:3]2[N:9]=[CH:10][NH:8][C:4]=2[CH:5]=[CH:6][CH:7]=1

Participants

Reactant 2

HCID 284Formic Acid

HCID 124898393-Bromobenzene-1,2-diamine

Product 1

HCID 112525844-Bromo-1H-benzimidazoleYield 95%

Procedure

A mixture of 3-bromobenzene-1,2-diamine (1.5 g, 8 mmol) in formic acid (10 mL) was heated at reflux for 2 h. The reaction mixture was concentrated in vacuo. To the residue was added a satd. aq. solution of NaHCO3 and mixture was extracted with EtOAc. The combined extracts was dried (MgSO4), filtered, and evaporated in vacuo to afford 4-bromo-1H-benzo[d]imidazole as a gray solid (1.5 g, 95%). MS (ESI): m/z=197 [M+1]+.

Workup

temperaturewas heated
temperatureat reflux for 2 h
concentrationThe reaction mixture was concentrated in vacuo
additionTo the residue was added a satd
extractionaq. solution of NaHCO3 and mixture was extracted with EtOAc
dry with materialThe combined extracts was dried (MgSO4)
filtrationfiltered
customevaporated in vacuo

Sources & evidence

ORD record: ord-77048661ffa64f14b2bd1fd072aa6b18
Source dataset: uspto-grants-2014_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08637537B2

Reaction notes

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