2,4-Dimethylpyridine → 5-Bromo-2,4-dimethylpyridine

HRID 1084328Notes

Reaction equation

HRID 1084328 reaction equation
OS(O)(=O)=O.O=S(=O)=O.[CH3:10][C:11]1[CH:16]=[C:15]([CH3:17])[CH:14]=[CH:13][N:12]=1.[Br:18]Br.C([O-])([O-])=O.[Na+].[Na+]>>[Br:18][C:14]1[C:15]([CH3:17])=[CH:16][C:11]([CH3:10])=[N:12][CH:13]=1.[Br:18][C:16]1[C:11]([CH3:10])=[N:12][CH:13]=[CH:14][C:15]=1[CH3:17]

Participants

6

Reactant 4

HCID 79362,4-DimethylpyridineHCID 10340Sodium CarbonateHCID 24408BromineHCID 24681Fuming sulfuric acid

Product 2

HCID 134111005-Bromo-2,4-dimethylpyridineHCID 140030643-Bromo-2,4-dimethylpyridine

Procedure

150 ml of 65% strength oleum are added dropwise to 28.9 ml of 2,4-dimethylpyridine, while cooling with ice and stirring, such that the temperature does not rise above 35° C. When the solution has become homogeneous, 6.42 ml of bromine are slowly added dropwise, with stirring. The mixture is stirred at 80° C. for 31/2 hours. After cooling, it is carefully added dropwise to 1 kg of ice, neutralized with solid Na2CO3 and extracted 3 times with 300 ml of ether each time. The organic layer is separated off and dried over magnesium sulfate. After removal of the solvent by distillation in vacuo, 34.6 g of a pale yellow oil consisting of the isomers 5-bromo-2,4-dimethylpyridine and 3-bromo-2,4-dimethylpyridine are obtained. The isomers are separated by column chromatography on silicon dioxide gel to give 10 g of 5-bromo-2,4-dimethylpyridine as a colorless liquid (13.0 g of 3-bromo-2,4-dimethylpyridine).

Workup

  1. temperaturewhile cooling with ice
  2. customdoes not rise above 35° C
  3. stirringwith stirring
  4. stirringThe mixture is stirred at 80° C. for 31/2 hours
  5. temperatureAfter cooling
  6. extractionextracted 3 times with 300 ml of ether each time
  7. customThe organic layer is separated off
  8. dry with materialdried over magnesium sulfate
  9. customAfter removal of the solvent
  10. distillationby distillation in vacuo, 34.6 g of a pale yellow oil
  11. customare obtained
  12. customThe isomers are separated by column chromatography on silicon dioxide gel

Sources & evidence

ORD record
ord-1b250b7748c64548840c6339ce197675
Source dataset
uspto-grants-1991_04
Patent number
US05004748

Reaction notes

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