Hydrochloric Acid → Ethyl 2-(3-nitrophenyl)benzimidazole-4-carboxylate

HRID 505913Notes

Reaction equation

HRID 505913 reaction equation
[NH2:1][C:2]1[C:12]([NH2:13])=[CH:11][CH:10]=[CH:9][C:3]=1[C:4]([O:6][CH2:7][CH3:8])=[O:5].[N+:14]([C:17]1[CH:24]=[CH:23][C:20](C=O)=[CH:19][CH:18]=1)([O-:16])=[O:15].Cl.O.[S-2].[Na+].[Na+].[CH3:30]O>O.C([O-])(=O)C.[Cu+2].C([O-])(=O)C.C(O)(=O)C>[N+:14]([C:17]1[CH:18]=[C:19]([C:30]2[NH:1][C:2]3[C:3]([C:4]([O:6][CH2:7][CH3:8])=[O:5])=[CH:9][CH:10]=[CH:11][C:12]=3[N:13]=2)[CH:20]=[CH:23][CH:24]=1)([O-:16])=[O:15]

Participants

9

Reactant 5

HCID 313Hydrochloric AcidHCID 5414-NitrobenzaldehydeHCID 887Methanol2×HCID 11171330Ethyl 2,3-diaminobenzoateHCID 19906495Sodium sulfide monohydrate

Product 1

HCID 178468756Ethyl 2-(3-nitrophenyl)benzimidazole-4-carboxylate

Reagents, catalysts & solvents 3

HCID 8895Cupric acetateCatalystHCID 176Acetic AcidSolventHCID 962WaterSolvent2×

Conditions

Temperature
50 °C

Procedure

4.2 g (23 mmol) of ethyl 2,3-diaminobenzoate and 3.1 ml of concentrated acetic acid were dissolved in 100 ml of methanol. 4.5 g (30 mmol) of 4-nitrobenzaldehyde, dissolved in 150 ml of methanol, were then added dropwise over a period of 30 minutes. 6 g (30 mmol) of copper(II) acetate, dissolved in 150 ml of warm water, were then rapidly added dropwise, and the entire mixture was subsequently refluxed for 20 minutes. The reaction solution was cooled to 50° C. and 8.3 ml of concentrated hydrochloric acid were added. This was followed by careful dropwise addition of a solution of 8.6 g of sodium sulfide hydrate in 100 ml of water, and the entire mixture was stirred for another 15 minutes. The reaction solution was poured into ice-water and the resulting precipitate was filtered off with suction. The filtrate was made alkaline using aqueous sodium bicarbonate solution and extracted repeatedly with ethyl acetate. The ethyl acetate phase was separated off, dried and concentrated under reduced pressure. This gave 6.1 g of the intermediate.

Workup

  1. additionwere then added dropwise over a period of 30 minutes
  2. additionwere then rapidly added dropwise
  3. temperaturethe entire mixture was subsequently refluxed for 20 minutes
  4. filtrationthe resulting precipitate was filtered off with suction
  5. extractionextracted repeatedly with ethyl acetate
  6. customThe ethyl acetate phase was separated off
  7. customdried
  8. concentrationconcentrated under reduced pressure

Sources & evidence

ORD record
ord-51b9fa89093546a19c03d3fc93a99ece
Source dataset
uspto-grants-2010_08
Patent number
US07781596B1

Reaction notes

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