Sulfuric Acid → 3,4-Difluorophenylboric acid

HRID 486362

Reaction equation

HRID 486362 reaction equation
Br[C:2]1[CH:7]=[CH:6][C:5]([F:8])=[C:4]([F:9])[CH:3]=1.[Mg].[B:11]([O:20]C(C)C)([O:16]C(C)C)[O:12]C(C)C.S(=O)(=O)(O)O>O1CCCC1>[F:9][C:4]1[CH:3]=[C:2]([O:12][B:11]([OH:20])[OH:16])[CH:7]=[CH:6][C:5]=1[F:8]

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 21531Triisopropyl borateHCID 676754-Bromo-1,2-difluorobenzeneHCID 5462224Magnesium

Product 1

HCID 218696723,4-Difluorophenylboric acid

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Conditions

Temperature
-65 °C

Procedure

A Grignard reagent solution prepared from 46.8 g of 1-bromo-3,4-difluorobenzene and 6 g of magnesium in 150 ml of tetrahydrofuran is added dropwise at -65° C. under nitrogen to a solution of 72.8 ml of triisopropyl borate in 200 ml of tetrahydrofuran. The mixture is stirred at -65° C. for 1 hour, warmed to 14°-20° C., treated dropwise with 100 ml of 10 percent (v/v) sulphuric acid, left to stand overnight and the separated salt is filtered off. The aqueous phase of the filtrate is separated and extracted with diethyl ether. The organic phases are combined, washed with sodium chloride solution, dried over sodium sulphate and evaporated. After boiling with hexane the residue gives 22.1 g of colourless 3,4-difluorophenylboric acid m.p. 275°-277.5° C. (sublimed).

Workup

  1. temperaturewarmed to 14°-20° C.
  2. waitleft
  3. waitto stand overnight
  4. filtrationthe separated salt is filtered off
  5. customThe aqueous phase of the filtrate is separated
  6. extractionextracted with diethyl ether
  7. washwashed with sodium chloride solution
  8. dry with materialdried over sodium sulphate
  9. customevaporated

Sources & evidence

ORD record
ord-45bf03eb5ae64496aed4ad0a8ca2a381
Source dataset
uspto-grants-1994_03
Patent number
US05292452

Linked notes

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