Notes
Slide Show
Outline
1
Chapter 7
  • Alkenes: Reactions and Synthesis
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Goals
  • After this chapter, you should be able to:
    • Show various elimination preparations for alkenes
    • Give products for various addition reaction of:
      • Halogens
      • Water
      • Carbene
      • Hydrogen
    • Give products for reaction of alkene:
      • Cleavage
      • Radical polymerization
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Introduction
  • Alkene are important because they can be used to synthesize
    • Alcohols   ROH
    • Alkanes
    • Diols          HOC-COH
    • Carbonyl compounds C=O
    • Cyclo compounds
    • Halides        R-X  where X=Cl, Br
    • Dihalides     X-C-C-X
    • Halohydrins  HO-C-C-X
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Alkene Synthesis
  • Elimination Reactions
    • Halogens with base





    • Alcohols with acid
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Alkene: Addition of Halogens
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Alkene: Addition of Halogens
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The Bromonium Ion Intermediate
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Halohydrin Formation
  • If another nucleophile is present, the bromonium ion can be intercepted.
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Halohydrin Formation
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Addition of Water to Alkenes
  • Acid catalyzed addition - H3PO4 and heat
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Addition of Water to Alkenes
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Oxymercuration – Demurcuration
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Oxymercuration – Demurcuration
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Hydroboration - Oxidation
  • Gives anti-Markovnikov addition of -OH
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Carbene Addition
  • Carbenes are extremely reactive and can add to a double bond forming cyclopropane
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Carbene Formation
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Carbenoids: For Non-halogenated
Cyclopropanes
  • The reagent is a metal-complex prepared by addition of CH2I2 and Zn(Cu) alloy in ether solvent.
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Carbene Addition
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Reduction of Alkenes
  • Catalytic addition of hydrogen (H2)
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Oxidation of Alkenes –
Diol formation
  • Hydroxylation
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Ozonolysis–Double bond Cleavage
Di-aldehyde formation
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Double Bond Oxidation–
(Poor to moderate  yield)
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1,2 Diol Cleavage
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The polymerization process of Addition or Chain-Reaction Polymerization consists of three steps:
  • Initiation – Typically benzoyl peroxide




  • Propagation – Free radical propagate through double bonds
  • Termination – Radicals collide.
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Addition Polymerization
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Addition Polymerization
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Addition Polymerization
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Cationic Polymerization –
Acid Catalyzed Polymerization
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Polystyrene through acid catalyzed polymerization.
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Give Products for the following
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