Phosphorus tribromide → 1-Bromo-6,6-dimethylhept-2-en-4-yne

HRID 851162Notes

Reaction equation

HRID 851162 reaction equation
P(Br)(Br)[Br:2].[CH3:5][C:6]([CH3:14])([CH3:13])[C:7]#[C:8][CH:9](O)[CH:10]=[CH2:11]>Br>[Br:2][CH2:11][CH:10]=[CH:9][C:8]#[C:7][C:6]([CH3:14])([CH3:13])[CH3:5]

Participants

4

Reactant 2

HCID 24614Phosphorus tribromideHCID 109755616,6-dimethylhept-1-en-4-yn-3-ol

Product 1

HCID 454895941-Bromo-6,6-dimethylhept-2-en-4-yne

Reagents, catalysts & solvents 1

HCID 260Hydrogen BromideSolvent

Procedure

50 ml 48% HBr and 10 g PBr3 are stirred to homogeneity at 40°. An alcoholic solution of 13.5 g of 6,6-dimethyl-hept-1-en-4-yn-3-ol is then added dropwise at 10° and the resulting mixture stirred at room temperature for 11/2 hours. The reaction mixture is poured onto ice-water and repeatedly extracted with hexane. The organic phase is separated, washed repeatedly with aqueous NaCl, dried and concentrated on a rotary evaporator. NMR spectroscopy reveals that the resulting oily reaction product comprises a 3:1 mixture of trans- and cis-1-bromo-6,6-dimethyl-hept-2-en-4-yne which is employed directly in further alkylation.

Workup

  1. additionThe reaction mixture is poured onto ice-water
  2. extractionrepeatedly extracted with hexane
  3. customThe organic phase is separated
  4. washwashed repeatedly with aqueous NaCl
  5. customdried
  6. concentrationconcentrated on a rotary evaporator
  7. additiona 3:1 mixture of trans- and cis-1-bromo-6,6-dimethyl-hept-2-en-4-yne which

Sources & evidence

ORD record
ord-1edd2eeef4db4cc8bcc7d985ae6da391
Source dataset
uspto-grants-1983_05
Patent number
US04382951

Reaction notes

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