Sulfuric Acid → Tert-butyl 3,5-difluorobenzoate

HRID 83886

Reaction equation

HRID 83886 reaction equation
OS(O)(=O)=O.[O-]S([O-])(=O)=O.[Mg+2].[F:12][C:13]1[CH:14]=[C:15]([CH:19]=[C:20]([F:22])[CH:21]=1)[C:16]([OH:18])=[O:17].[CH3:23][C:24](O)([CH3:26])[CH3:25]>C1(C)C=CC=CC=1>[F:12][C:13]1[CH:14]=[C:15]([CH:19]=[C:20]([F:22])[CH:21]=1)[C:16]([O:18][C:24]([CH3:26])([CH3:25])[CH3:23])=[O:17]

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 6386tert-ButanolHCID 24083Sulfuric acid magnesium salt (1:1)HCID 1012653,5-Difluorobenzoic acid

Product 1

HCID 21925017Tert-butyl 3,5-difluorobenzoateYield 78.3%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

Concentrated H2SO4 (1.74 mL, 31.6 mmol) was added to a vigorously stirred suspension of MgSO4 (15.2 g, 126.4 mmol, 4 eq) in toluene (100 mL). The mixture was stirred for 15 minutes, after which 3,5-difluorobenzoic acid (5 g, 31.6 mmol) and t-BuOH (14.9 mL, 158 mmol, 5 eq) were added successively. The mixture was stoppered tightly and stirred at room temperature until the reaction was complete by TLC analysis. The reaction mixture was then quenched with saturated NaHCO3 solution and stirred until all MgSO4 had dissolved. The organic layer was washed with brine, dried over MgSO4 and concentrated to afford the crude product. The residue was purified by chromatography (silica, Hex) to give tert-butyl 3,5-difluorobenzoate (5.3 g, 78%) as a colorless oil.

Workup

  1. stirringstirred at room temperature until the reaction
  2. customThe reaction mixture was then quenched with saturated NaHCO3 solution
  3. stirringstirred until all MgSO4
  4. dissolutionhad dissolved
  5. washThe organic layer was washed with brine
  6. dry with materialdried over MgSO4
  7. concentrationconcentrated
  8. customto afford the crude product
  9. customThe residue was purified by chromatography (silica, Hex)

Sources & evidence

ORD record
ord-dccd3a94003d481a99d6c72313b8234b
Source dataset
uspto-grants-2014_09
Patent number
US08846739B2

Linked notes

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