Acetic Acid → 4-Bromo-3-fluorobenzylidene diacetate

HRID 346262Notes

Reaction equation

HRID 346262 reaction equation
[C:1]([O:4][C:5](=[O:7])[CH3:6])(=[O:3])[CH3:2].[Br:8][C:9]1[CH:14]=[CH:13]C(C)=[CH:11][C:10]=1[F:16].S(=O)(=O)(O)O.[C:22](O)(=[O:24])[CH3:23]>[O-2].[O-2].[O-2].[Cr+6]>[C:1]([O:4][CH:5]([O:7][C:22](=[O:24])[CH3:23])[C:6]1[CH:13]=[CH:14][C:9]([Br:8])=[C:10]([F:16])[CH:11]=1)(=[O:3])[CH3:2]

Participants

6

Reactant 4

HCID 176Acetic AcidHCID 1118Sulfuric AcidHCID 7918Acetic AnhydrideHCID 5732804-Bromo-3-fluorotoluene

Product 1

HCID 536330654-Bromo-3-fluorobenzylidene diacetate

Reagents, catalysts & solvents 1

HCID 10219390chromium (VI) trioxideCatalyst

Procedure

A mixture of acetic acid (108 ml), acetic anhydride (0.58 ml) and 4-bromo-3-fluorotoluene (20 g) was cooled to -10° when concentrated sulphuric acid (22.5 mls) was added dropwise, such that the temperature did not exceed -5°. When the addition was complete, chromium trioxide (31.3 g) was added portionwise at such a rate that the temperature did not exceed 5°. The resulting mixture was stirred for 30 minutes and then poured onto ice (300 g). The reaction mixture was then extracted with diethyl ether and the combined ethereal extracts were washed with 2M sodium hydroxide and brine before drying over anhydrous magnesium sulphate and evaporation in vacuo. Recrystallisation from hexane gave 4-bromo-3-fluorobenzylidene diacetate (15 g).

Workup

  1. additionwas added dropwise, such that the temperature
  2. customdid not exceed -5°
  3. additionWhen the addition
  4. customdid not exceed 5°
  5. additionpoured onto ice (300 g)
  6. extractionThe reaction mixture was then extracted with diethyl ether
  7. washthe combined ethereal extracts were washed with 2M sodium hydroxide and brine
  8. dry with materialbefore drying over anhydrous magnesium sulphate and evaporation in vacuo
  9. customRecrystallisation from hexane

Sources & evidence

ORD record
ord-dd49d6d3d1fb40b4aa57fb8efb03ef0e
Source dataset
uspto-grants-1991_10
Patent number
US05061726

Reaction notes

Loading…