Acetic Acid → 5,6-difluoro-1H-benzimidazole-2-thiol

HRID 1709765Notes

Reaction equation

HRID 1709765 reaction equation
Cl.Cl.[F:3][C:4]1[C:9]([F:10])=[CH:8][C:7]([NH2:11])=[C:6]([NH2:12])[CH:5]=1.[OH-].[K+].CCO[C:18]([S-])=[S:19].[K+].C(O)(=O)C>C(O)(C)C.O>[F:3][C:4]1[C:9]([F:10])=[CH:8][C:7]2[N:11]=[C:18]([SH:19])[NH:12][C:6]=2[CH:5]=1

Participants

7

Reactant 4

HCID 176Acetic AcidHCID 14797Potassium HydroxideHCID 2735045Potassium ethylxanthateHCID 230365074,5-Difluoro-o-phenylenediamine dihydrochloride

Product 1

HCID 106791065,6-difluoro-1H-benzimidazole-2-thiol

Reagents, catalysts & solvents 2

HCID 962WaterSolvent2×HCID 3776IsopropanolSolvent

Procedure

40.7 g of 4,5-difluoro-o-phenylenediamine dihydrochloride were suspended in 655 ml of isopropanol. A solution of 22.5 g of potassium hydroxide in 250 ml of water was added dropwise thereto while stirring and the mixture was treated with 39.7 g of potassium ethyl xanthogenate, whereupon the solution was boiled at reflux overnight, then diluted with 300 ml of water and made neutral with glacial acetic acid. The resulting suspension was stirred at 60°-70° for an additional hour. The isopropanol was largely removed from the mixture in a vacuum. After the addition of 1 liter of water, the solid was filtered off washed with water and then dissolved in ether. The solution was then extracted with 1.2 liters of water, treated with active charcoal, dried and evaporated in a vacuum. The residue was suspended in petroleum etber (low boiling) and filtered off. There was obtained 5,6-difluoro-2-benzimidazolethiol of melting point above 300°.

Workup

  1. temperatureat reflux overnight
  2. stirringThe resulting suspension was stirred at 60°-70° for an additional hour
  3. customThe isopropanol was largely removed from the mixture in a vacuum
  4. additionAfter the addition of 1 liter of water
  5. filtrationthe solid was filtered off
  6. washwashed with water
  7. dissolutiondissolved in ether
  8. extractionThe solution was then extracted with 1.2 liters of water
  9. additiontreated with active charcoal
  10. customdried
  11. customevaporated in a vacuum
  12. filtrationfiltered off

Sources & evidence

ORD record
ord-9e628bdfb86d491f967d2a432944cce0
Source dataset
uspto-grants-1990_08
Patent number
US04950677

Reaction notes

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