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ALKENES - Coggle Diagram

- - - - How it work
        
        The leaving group leaves on its own, creating a stable carbocation intermediate.
        
        A weak base comes in and plucks a proton H+ from the beta-carbon, and the remaining electrons collapse to form a double bond.
      - Rate Law: Rate = k [substrate]
    - - How it work
        
        It is a concerted, one-step process. Everything happens at the exact same time. The strong base grabs the beta -proton, the electrons shift to form the double bond, and the leaving group gets kicked out all at once.
      - Rate = k [substrate] [base]
    - - The more highly substituted, more stable alkene will be the preferred product.
      - If a base ( NaOH, NaOEt) has a choice, it will usually take the hydrogen from the beta-carbon that has fewer hydrogens to begin with. This results in an alkene with more alkyl groups attached to the double bond.
    - - The less substituted, less stable alkene is formed. ( Bulky, sterically hindered bases like potassium tert-butoxide, t-BuOK)
  - - - Reagents: H2 gas with Lindlar's catalyst
      - Stereochemistry: Syn addition.
    - - Reagents: Sodium (Na) or lithium (Li) metal dissolved in liquid ammonia (NH3) at very low temperatures.
      - Stereochemistry: Anti addition.