Epoxides

• Epoxides


  Three membered-cyclic ether, also called oxirane
• Epoxides


  • Valuable synthetic intermediates used for converting alkenes to a variety of other functional groups
• Conversion of alkene to epoxide

  Reaction with peroxyacid, RCOOOH
• Peroxyacid


  Carboxylic acid that has an extra oxygen atom in a -O-O- (peroxy) linkage
• Epoxide nomenclature (common name)


  Formed by adding "oxide" to the name of the alkene that is oxidised
• Epoxide nomenclature (systematic)


  Named as derivatives of the parent compound, ethylene oxide, using "oxirane" as the systematic name for ethylene oxide
• Epoxide synthesis (from alkenes)

  Reaction with peroxyacids, RCOOOH
• Epoxide synthesis (from halohydrins)


  1. Base promoted cyclization of halohydrins

  2. Intramolecular SN2 attack of internal alkoxide on carbon bearing halogen leaving group
• Halohydrin


  Molecule with halogen bonded to the β-carbon bearing an -OH group
• Halohydrin preparation


  Reaction of alkene with halogen in presence of water
• Other cyclic ethers


  • Oxetanes
  • Furans (oxolanes)
  • Pyrans (Oxanes)
• Epoxide reacts with Grignard reagent

  Produces alcohol bearing two more carbons than the parent Grignard molecule
• First test for epoxides: Stereochemistry to alcohols