Iodine → 2-Bromo-4-fluorotoluene

HRID 1703409Notes

Reaction equation

HRID 1703409 reaction equation
[Br:1]Br.[F:3][C:4]1[CH:9]=[CH:8][C:7]([CH3:10])=[CH:6][CH:5]=1.II.O>C(O)(=O)C.[Fe]>[Br:1][C:8]1[CH:9]=[C:4]([F:3])[CH:5]=[CH:6][C:7]=1[CH3:10].[Br:1][C:5]1[CH:6]=[C:7]([CH3:10])[CH:8]=[CH:9][C:4]=1[F:3]

Participants

8

Reactant 4

HCID 807IodineHCID 962Water2×HCID 9603p-FluorotolueneHCID 24408Bromine

Product 2

HCID 740162-Bromo-4-fluorotolueneHCID 967453-Bromo-4-fluorotoluene

Reagents, catalysts & solvents 2

HCID 23925IronCatalystHCID 176Acetic AcidSolvent2×

Procedure

A solution of 160 g of bromine in 60 ml of glacial acetic acid was added, in the course of 3 hours, to a solution of 110 g of 4-fluorotoluene in 40 ml of glacial acetic acid, to which 1.1 g of iron powder and 1.1 g of iodine had been added. The initially exothermic reaction was kept at 25° C. to 27° C., first by cooling with water and then with warm water. The mixture was subsequently stirred at the above temperature for 8 hours, the glacial acetic acid and unreacted 4-fluorotoluene were then distilled off under normal pressure up to a temperature of 120° C. and a mixture consisting of 3-bromo-4-fluorotoluene (62%), 2-bromo-4-fluorotoluene (32%) and dibromo-4-fluorotoluene (5%) was subsequently distilled off under 20 mbars and between 65° C. and 85° C. 34 g of residue remained. The monobrominated isomers were separated by distillation on a column. 12.7 g of 2-bromo-4-fluorotoluene (boiling point: 176°-8° C. (normal pressure), nD20 : 1.5260) and 24.5 g of 3-bromo-4-fluorotoluene (boiling point: 184°-5° C., (normal pressure), nD20 : 1.5303) were obtained.

Workup

  1. additionhad been added
  2. customThe initially exothermic reaction
  3. customwas kept at 25° C. to 27° C.
  4. distillationthe glacial acetic acid and unreacted 4-fluorotoluene were then distilled off under normal pressure up to a temperature of 120° C.
  5. distillationwas subsequently distilled off under 20 mbars and between 65° C. and 85° C
  6. customThe monobrominated isomers were separated by distillation on a column

Sources & evidence

ORD record
ord-c9fe7d6adbad4001a7be514025a4334d
Source dataset
uspto-grants-1982_09
Patent number
US04351974

Reaction notes

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