4-Bromobenzaldehyde → (E)-3,4'-dibromostilbene

HRID 440824Notes

Reaction equation

HRID 440824 reaction equation
[Br-].[Br:2][C:3]1[CH:4]=[C:5]([CH:26]=[CH:27][CH:28]=1)[CH2:6][P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.[Br:29][C:30]1[CH:37]=[CH:36][C:33]([CH:34]=O)=[CH:32][CH:31]=1>O1CCCC1>[Br:2][C:3]1[CH:4]=[C:5](/[CH:6]=[CH:34]/[C:33]2[CH:36]=[CH:37][C:30]([Br:29])=[CH:31][CH:32]=2)[CH:26]=[CH:27][CH:28]=1

Participants

4

Reactant 2

HCID 707414-BromobenzaldehydeHCID 19034144[(3-Bromophenyl)methyl](triphenyl)phosphanium bromide

Product 1

HCID 9997242(E)-3,4'-dibromostilbene

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

A solution of 38.0 g of (3-bromo-benzyl)-triphenylphosphonium bromide, known from the literature, in 250 ml of tetrahydrofuran was treated at -10° C. with 8.75 g of potassium tert.-butylate and stirred for 3 minutes. A solution of 14.8 g of 4-bromobenzaldehyde was added dropwise to the yellow-orange suspension within 15 minutes. After stirring for 60 minutes the reaction mixture was concentrated. The residue was treated with ice-water and extracted with ethyl acetate/ether. The organic phases were washed with water and saturated aqueous sodium chloride solution, dried over magnesium sulfate and evaporated. The residue was chromatographed over silica gel with hexane and hexane/ether 99:1 and gave (E)-3,4'-dibromostilbene as colourless crystals, MS: m/z 338 (M+), as well as (Z)-3,4'-dibromostilbene as a colourless oil, MS: m/z 338 (M+).

Workup

  1. stirringAfter stirring for 60 minutes the reaction mixture
  2. concentrationwas concentrated
  3. additionThe residue was treated with ice-water
  4. extractionextracted with ethyl acetate/ether
  5. washThe organic phases were washed with water and saturated aqueous sodium chloride solution
  6. dry with materialdried over magnesium sulfate
  7. customevaporated
  8. customThe residue was chromatographed over silica gel with hexane and hexane/ether 99:1

Sources & evidence

ORD record
ord-43c67419202641e7ac61d74d2678cccb
Source dataset
uspto-grants-1996_05
Patent number
US05521160

Reaction notes

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