Sodium Dithionite → 2-Chloro-6,7,8-trifluoro-3-quinolinecarboxylic acid

HRID 344885Notes

Reaction equation

HRID 344885 reaction equation
[Mn]([O-])(=O)(=O)=O.[K+].[Cl:7][C:8]1[NH:9][C:10]2[C:15]([CH2:16][C:17]=1[CH:18]=[O:19])=[CH:14][C:13]([F:20])=[C:12]([F:21])[C:11]=2[F:22].S(S([O-])=O)([O-])=[O:24].[Na+].[Na+]>O.[OH-].[K+]>[Cl:7][C:8]1[C:17]([C:18]([OH:24])=[O:19])=[CH:16][C:15]2[C:10](=[C:11]([F:22])[C:12]([F:21])=[C:13]([F:20])[CH:14]=2)[N:9]=1

Participants

6

Reactant 3

HCID 24489Sodium DithioniteHCID 516875Potassium PermanganateHCID 856115502-Chloro-6,7,8-trifluoro-3-formyl-1,4-dihydroquinoline

Product 1

HCID 543512652-Chloro-6,7,8-trifluoro-3-quinolinecarboxylic acidYield 257.5%

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 14797Potassium HydroxideSolvent

Conditions

Temperature
10 °C

Procedure

A solution of potassium permanganate (69.65 g) in water (730 cc) is added in the course of 1 hour to a stirred suspension, cooled to approximately 10° C., of 2-chloro-6,7,8-trifluoro-3-formyl-1,4-dihydroquinoline (45.7 g) in N potassium hydroxide (585 cc), while the temperature is maintained at between 10° and 14° C. The mixture is left stirring for a further 30 minutes at approximately 10° C. Sodium dithionite (12 g) is added and the mixture is stirred for 10 minutes at a temperature in the region of 10° C., filtered through diatomaceous silica and washed with water (3×400 cc). The filtrate and washings are combined and treated with 35% strength aqueous hydrochloric acid solution (70 cc). The precipitate formed is extracted with ethyl acetate (3×500 cc). The combined organic extracts are dried over magnesium sulphate, filtered and concentrated under reduced pressure (20 kPa) at 50° C. The residue is taken up with a mixture of ethyl ether (100 cc) and isopropyl ether (100 cc), drained and washed with the same mixture (100 cc). 2-Chloro-6,7,8-trifluoro-3-quinolinecarboxylic acid (46.43 g) is obtained in the form of a colorless solid, decomposing at 225°-230° C., which is used without further purification for the subsequent steps.

Workup

  1. temperatureis maintained at between 10° and 14° C
  2. waitThe mixture is left
  3. stirringthe mixture is stirred for 10 minutes at a temperature in the region of 10° C.
  4. filtrationfiltered through diatomaceous silica
  5. washwashed with water (3×400 cc)
  6. additiontreated with 35% strength aqueous hydrochloric acid solution (70 cc)
  7. customThe precipitate formed
  8. extractionis extracted with ethyl acetate (3×500 cc)
  9. dry with materialThe combined organic extracts are dried over magnesium sulphate
  10. filtrationfiltered
  11. concentrationconcentrated under reduced pressure (20 kPa) at 50° C
  12. additionThe residue is taken up with a mixture of ethyl ether (100 cc) and isopropyl ether (100 cc)
  13. washwashed with the same mixture (100 cc)

Sources & evidence

ORD record
ord-5a5b366f0bfe4e89bbcf42730a167c5a
Source dataset
uspto-grants-1991_10
Patent number
US05053509

Reaction notes

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