Ethylene → 6-Bromo-2-tetralone

HRID 2289225Notes

Reaction equation

HRID 2289225 reaction equation
[CH2:1]=[CH2:2].[Br:3][C:4]1[CH:9]=[CH:8][C:7]([CH2:10][C:11](Cl)=[O:12])=[CH:6][CH:5]=1.[Cl-].[Al+3].[Cl-].[Cl-]>C(Cl)Cl>[Br:3][C:4]1[CH:9]=[C:8]2[C:7](=[CH:6][CH:5]=1)[CH2:10][C:11](=[O:12])[CH2:2][CH2:1]2

Participants

5

Reactant 3

HCID 6325Ethylene3×HCID 181552Benzeneacetyl chloride, 4-bromo-2×HCID 6451240Aluminum(III) Chloride

Product 1

HCID 27335536-Bromo-2-tetralone

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Conditions

Temperature
-10 °C

Procedure

To a two-litre round bottom flask equipped with a gas inlet tube connected to an external tank of ethylene, an add ition funnel containing a solution of the crude 4-bromophenylacetyl chloride described above in methylene chloride (75 ml), a thermometer, a gas inlet adapter connected to a bubbler and a positive nitrogen flow, and a heavy-duty magnetic stirrer was added dry methylene chloride (1000 ml) and aluminium chloride (56 g, 0.42 mole). The stirred suspension was cooled to -10° C. using an ice/salt bath, and ethylene was introduced through the gas inlet tube, which was positioned just above the vortex. Dropwise addition of the phenylacetyl chloride solution was started at a moderate rate, and adjusted periodically so that the reaction temperature stayed below 0° C. Ethylene flow was continued for 30 minutes after addition of the acid chloride solution was complete, and then reaction mixture was poured over 2000 ml of ice, stirred vigorously for a few minutes, and left to sit until the ice melted. The methylene chloride layer was separated and the aqueous layer was extracted three times with methylene chloride (100 ml each). Combined methylene chloride layers were filtered through a short silica gel plug and then evaporated under reduced pressure to leave an amber-colored oil, which was purified using silica gel column chromatrography, eluting with ethyl acetate:hexane (35:65) to give 6-bromo-2-tetralone as an amber crystalline solid. (25 g, 95%).

Workup

  1. customTo a two-litre round bottom flask equipped with a gas inlet tube
  2. additionan add ition funnel
  3. customstayed below 0° C
  4. customreaction mixture
  5. waitleft
  6. customThe methylene chloride layer was separated
  7. extractionthe aqueous layer was extracted three times with methylene chloride (100 ml each)
  8. filtrationCombined methylene chloride layers were filtered through a short silica gel plug
  9. customevaporated under reduced pressure
  10. customto leave an amber-colored oil, which
  11. customwas purified
  12. washeluting with ethyl acetate:hexane (35:65)

Sources & evidence

ORD record
ord-c9763e7ba74a4a05a75c425b2f1bb58e
Source dataset
uspto-grants-2000_07
Patent number
US06090941

Reaction notes

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