Phosphorus oxychloride → 2-Chlorobenzimidazole

HRID 1886036Notes

Reaction equation

HRID 1886036 reaction equation
O[C:2]1[NH:3][C:4]2[CH:10]=[CH:9][CH:8]=[CH:7][C:5]=2[N:6]=1.P(Cl)(Cl)([Cl:13])=O>>[Cl:13][C:2]1[NH:3][C:4]2[CH:10]=[CH:9][CH:8]=[CH:7][C:5]=2[N:6]=1

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 178517141HCID 178517141, compound

Product 1

HCID 785722-ChlorobenzimidazoleYield 57%

Procedure

According to the procedure D. Harrison, et al., J. Chem. Soc., 2930, 1963, a mixture of 2-hydroxybenzimidazole (40.0 g, 0.298 mol) and phosphoryl chloride (400 mL) was heated under reflux for 3 hours, cooled, and concentrated. The resulting slurry was poured onto ice and the solid (starting material) was removed by filtration. The filtrate was adjusted to pH 6 with 30% aqueous NH3 and the resulting white precipitate was collected by filtration and dried to give 26.1 g (57%) of product m.p. 184°-186° C.

Workup

  1. temperaturewas heated
  2. temperatureunder reflux for 3 hours
  3. temperaturecooled
  4. concentrationconcentrated
  5. additionThe resulting slurry was poured onto ice
  6. customthe solid (starting material) was removed by filtration
  7. filtrationthe resulting white precipitate was collected by filtration
  8. customdried

Sources & evidence

ORD record
ord-e0acec2b19a449f7b8e33deca2ce6ea1
Source dataset
uspto-grants-1992_09
Patent number
US05149700

Reaction notes

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