Ammonium Hydroxide → 5,6-Difluoro-2-bromonaphthalene

HRID 2182113Notes

Reaction equation

HRID 2182113 reaction equation
[Br:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[C:8](F)([F:12])[C:7](F)([F:14])[CH:6]=[CH:5]2.[NH4+].[Cl-].[NH4+].[OH-]>[Zn].C1COCC1>[Br:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[C:8]([F:12])=[C:7]([F:14])[CH:6]=[CH:5]2

Participants

6

Reactant 3

HCID 14923Ammonium HydroxideHCID 25517Ammonium ChlorideHCID 224834376-Bromo-1,1,2,2-tetrafluoro-1,2-dihydronaphthalene

Product 1

HCID 114138325,6-Difluoro-2-bromonaphthaleneYield 83.3%

Reagents, catalysts & solvents 2

HCID 23994ZincCatalystHCID 8028TetrahydrofuranSolvent

Procedure

Zinc (7.18 g, 110 mmol) was added in two portions (4.74 g and 2.44 g) to a stirred mixture of 20.1 g (71.4 mmol) of 6-bromo-1,1,2,2-tetrafluoro-1,2-dihydronaphthalene, 45 ml of THF, 20.1 g of NH4Cl, and 90 ml of NH4OH that was cooled in an ice bath. The mixture was allowed to warm slowly to room temperature. After 5 hours reaction time, the zinc was removed by filtration. The phases were separated, and the aqueous layer was extracted three times with hexanes. The combined organic phase was washed twice with brine and dried over MgSO4. The MgSO4 was filtered off, and the solvent was removed under vacuum. Crude 6-bromo-1,2-difluoronaphthalene (16.7 g) containing 15% impurities (estimated) remained. The estimated yield of the crude 6-bromo-1,2-difluoronaphthalene was 86%. The crude yellow solid was sublimed at 70-80° C. Off-white needles (14.5 g, 59.5 mmol, 83% yield) were collected.

Workup

  1. temperaturewas cooled in an ice bath
  2. customAfter 5 hours reaction time
  3. customthe zinc was removed by filtration
  4. customThe phases were separated
  5. extractionthe aqueous layer was extracted three times with hexanes
  6. washThe combined organic phase was washed twice with brine
  7. dry with materialdried over MgSO4
  8. filtrationThe MgSO4 was filtered off
  9. customthe solvent was removed under vacuum
  10. additionCrude 6-bromo-1,2-difluoronaphthalene (16.7 g) containing 15% impurities (estimated)
  11. customwas sublimed at 70-80° C

Sources & evidence

ORD record
ord-bc67efd9539545adb37e99ba7614ac42
Source dataset
uspto-grants-2005_05
Patent number
US06894200B2

Reaction notes

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