Hydrochloric Acid → 4-Hydroxyindole-3-carboxaldehyde

HRID 25332

Reaction equation

HRID 25332 reaction equation
P(Cl)(Cl)(Cl)=O.[OH:6][C:7]1[CH:15]=[CH:14][CH:13]=[C:12]2[C:8]=1[CH:9]=[CH:10][NH:11]2.[OH-].[Na+].Cl.CN(C)[CH:21]=[O:22]>O>[OH:6][C:7]1[CH:15]=[CH:14][CH:13]=[C:12]2[C:8]=1[C:9]([CH:21]=[O:22])=[CH:10][NH:11]2

Participants

7

Reactant 5

HCID 313Hydrochloric AcidHCID 6228Dimethylformamide2×HCID 14798Sodium HydroxideHCID 24813Phosphorus oxychlorideHCID 754211H-indol-4-ol

Product 1

HCID 98152824-Hydroxyindole-3-carboxaldehydeYield 82%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

Phosphorous oxychloride 7.35 ml was added dropwise to dry dimethylformamide 15 ml under cooling in ice-methanol bath and the mixture was stirred for 15 min. Then, a solution of the 4-hydroxyindole 5.0 g in dry dimethylformamide 10 ml was added dropwise to the mixture under cooling in ice and the mixture was stirred for 2 h at room temperature. Water was added under cooling in ice to the mixture, which was made alkaline with a 30% aqueous sodium hydroxide solution and was stirred for 15 min. Then, the mixture was acidified to pH 4 with 5N-HCl and the precipitate was collected by filtration, washed with water and dried to give the titled compound 4.99 g as crude crystalline materials. Yield 82%. Crude crystalline materials are recrystallized from methanol to give yellow crystals m.p. 190-193° C.

Workup

  1. temperatureunder cooling in ice
  2. stirringthe mixture was stirred for 2 h at room temperature
  3. temperatureunder cooling in ice to the mixture, which
  4. stirringwas stirred for 15 min
  5. filtrationthe precipitate was collected by filtration
  6. washwashed with water
  7. customdried

Sources & evidence

ORD record
ord-2970d5c5affd4345a64be8337930ba6f
Source dataset
uspto-grants-2005_02
Patent number
US06858640B2

Linked notes

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