Ethyl Bromide → 1,4-Dipropionylbenzene

HRID 1199963Notes

Reaction equation

HRID 1199963 reaction equation
[Mg].Br[CH2:3][CH3:4].[CH:5](=[O:14])[C:6]1[CH:13]=[CH:12][C:9]([CH:10]=[O:11])=[CH:8][CH:7]=1.[Cl-].[NH4+].S([O-])([O-])(=O)=O.[Mg+2].[Cr](O)(O)(=O)=O.[CH2:28]1COC[CH2:29]1>BrCC.C(O)(=O)C.CC(C)=O.CCOCC.O.C(O)C>[C:10]([C:9]1[CH:12]=[CH:13][C:6]([C:5](=[O:14])[CH2:3][CH3:4])=[CH:7][CH:8]=1)(=[O:11])[CH2:28][CH3:29]

Participants

14

Reactant 7

HCID 6332Ethyl BromideHCID 8028Tetrahydrofuran5×HCID 12173TerephthalaldehydeHCID 24083Sulfuric acid magnesium salt (1:1)HCID 24425Chromic AcidHCID 25517Ammonium Chloride2×HCID 5462224Magnesium2×

Product 1

HCID 146236711,4-Dipropionylbenzene

Reagents, catalysts & solvents 6

HCID 6332Ethyl BromideCatalystHCID 176Acetic AcidSolventHCID 180AcetoneSolventHCID 702EthanolSolventHCID 962WaterSolventHCID 3283Diethyl EtherSolvent

Procedure

To initiate reaction several magnesium turnings and one drop of bromoethane were added to a mixture of magnesium powder (7.5 g) in a dry tetrahydrofuran, THF, (20 ml). Steady reflux was maintained by the portionwise addition of a solution of bromoethane (23 ml) in dry THF (50 ml). The solution was stirred under reflux for one hour, treated with a saturated solution of terephthalaldehyde (13.4 g) in THF, the resultant mixture was diluted with THF (100 ml) and stirred under reflux for 1/2 hour. The reaction mixture was allowed to cool to room temperature and was treated with saturated aqueous ammonium chloride (5 ml), ammonium chloride powder (2 g) and magnesium sulphate. The resultant mixture was stirred for one hour and filtered. The yellow filtrate was evaporated to dryness to yield a solid which was dissolved in a hot mixture of glacial acetic acid and acetone (1:1) and was added portionwise to aqueous chromic acid (1.67M, 150 ml). The solution was allowed to stand at room temperature for 2 days, and was then treated with ethanol (10 ml) and stirred for 1/2 hour. Water (200 ml) was added and the mixture was extracted with ethyl acetate. The combined ethyl acetate extracts were washed successively with water, dilute aqueous sodium bicarbonate, water and saturated aqueous ammonium chloride, dried (magnesium sulphate) and evaporated to dryness to afford a grey-green oil. Trituration with diethyletherpetroleum ether (b.p. 40°-60° C.) afforded a solid, which was eluted from a silica column with dichloromethane to afford as white crystals 1,4-dipropionylbenzene (2.4 g) m.p. 98°-101° C.

Workup

  1. temperatureSteady reflux
  2. temperatureunder reflux for one hour
  3. stirringstirred
  4. temperatureunder reflux for 1/2 hour
  5. filtrationfiltered
  6. customThe yellow filtrate was evaporated to dryness
  7. customto yield a solid which
  8. stirringstirred for 1/2 hour
  9. extractionthe mixture was extracted with ethyl acetate
  10. washThe combined ethyl acetate extracts were washed successively with water, dilute aqueous sodium bicarbonate, water and saturated aqueous ammonium chloride
  11. dry with materialdried (magnesium sulphate)
  12. customevaporated to dryness
  13. customto afford a grey-green oil
  14. washwas eluted from a silica column with dichloromethane

Sources & evidence

ORD record
ord-7638adba58e9446d96223f41a3f7e24d
Source dataset
uspto-grants-1990_02
Patent number
US04904664

Reaction notes

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