Ethylene Glycol → 2-(3-Bromophenyl)-2-methyl-1,3-dioxolane

HRID 2120466Notes

Reaction equation

HRID 2120466 reaction equation
[CH3:1][C:2]([C:4]1[CH:9]=[CH:8][CH:7]=[C:6]([Br:10])[CH:5]=1)=[O:3].[CH2:11](O)[CH2:12][OH:13].C1(C)C=CC(S(O)(=O)=O)=CC=1.O>C1(C)C=CC=CC=1>[CH3:1][C:2]1([C:4]2[CH:5]=[C:6]([Br:10])[CH:7]=[CH:8][CH:9]=2)[O:13][CH2:12][CH2:11][O:3]1

Participants

6

Reactant 4

HCID 174Ethylene GlycolHCID 962WaterHCID 6101p-Toluenesulfonic acidHCID 165023'-Bromoacetophenone

Product 1

HCID 109992182-(3-Bromophenyl)-2-methyl-1,3-dioxolaneYield 85%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

5 g (25 mmol) of 3-bromoacetophenone are dissolved in 40 ml of toluene and then 15 ml of ethylene glycol and 500 mg of para-toluenesulphonic acid are added. The reaction medium is then heated under reflux equipped with a Dean-Stark distillation assembly. After 12 h, the medium is cooled and then treated with water and extracted with dichloromethane. After drying and concentrating, the residue is purified on a silica column in order to obtain the desired 3-(2-methyl-[1,3]dioxolan-2-yl)-1-bromobenzene (Y=85%). This product (4 g, 16.4 mmol) is then dissolved in anhydrous THF and the mixture is cooled to −78° C. 7.2 ml (18 mmol) of a 2.5M solution of butyllithium are then added dropwise. After stirring for 1 hour at the same temperature, 1.9 ml (18 mmol) of dimethylformamide are added. The mixture is maintained at −78° C. for 30 minutes and then brought to room temperature. The reaction medium is then treated with a saturated ammonium chloride solution and extracted with dichloromethane. After purification by chromatography on a silica column (ethyl acetate 10-heptane 90), a colourless oil is obtained (m=3.09 g; Y=98%).

Workup

  1. temperatureThe reaction medium is then heated
  2. temperatureunder reflux
  3. customequipped with a Dean-Stark distillation assembly
  4. temperaturethe medium is cooled
  5. extractionextracted with dichloromethane
  6. customAfter drying
  7. concentrationconcentrating
  8. customthe residue is purified on a silica column in order

Sources & evidence

ORD record
ord-65c66e397458461884508b36b40ce846
Source dataset
uspto-grants-2004_02
Patent number
US06689922B1

Reaction notes

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