Formic Acid → 1,6-Dimethyl-1H-benzimidazole

HRID 1110816Notes

Reaction equation

HRID 1110816 reaction equation
[NH2:1][C:2]1[CH:7]=[CH:6][C:5]([CH3:8])=[CH:4][C:3]=1[NH:9][CH3:10].Cl.[CH:12](O)=O>>[CH3:10][N:9]1[C:3]2[CH:4]=[C:5]([CH3:8])[CH:6]=[CH:7][C:2]=2[N:1]=[CH:12]1

Participants

4

Reactant 3

HCID 284Formic AcidHCID 313Hydrochloric AcidHCID 9989323N1,5-Dimethylbenzene-1,2-diamine

Product 1

HCID 148567901,6-Dimethyl-1H-benzimidazoleYield 57%

Procedure

A mixture of 6.60 g of 1-amino-4-methyl-2-(N-methylamino)benzene and a solution of 3.5 ml of formic acid in 50 ml of a 4N HCl was stirred at 100° C. for 3.5 hours. The reaction solution was concentrated under reduced pressure and water was added to the residue. After washing with ethyl acetate, the aqueous phase was rendered alkaline with aqueous potassium carbonate followed by extraction with chloroform. The chloroform layer was washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography (40 g). Elution with ethyl acetate followed by recyrstallization from ethyl acetate-hexane gave 4.01 g (57%) of 1,6-dimethylbenzimidazole.

Workup

  1. concentrationThe reaction solution was concentrated under reduced pressure and water
  2. additionwas added to the residue
  3. washAfter washing with ethyl acetate
  4. extractionfollowed by extraction with chloroform
  5. washThe chloroform layer was washed with saturated sodium chloride solution
  6. dry with materialdried over anhydrous magnesium sulfate
  7. concentrationconcentrated under reduced pressure
  8. washElution with ethyl acetate

Sources & evidence

ORD record
ord-b01ce20c7c5c43329c7c5374c573aab5
Source dataset
uspto-grants-1990_12
Patent number
US04977175

Reaction notes

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