Elimination reaction of haloalkane

• What type of reaction is described between haloalkanes and hydroxide ions?

  Elimination reaction
• What do hydroxide ions act as in the elimination reaction?

  They act as a base
• What is formed when haloalkanes react with aqueous hydroxide ions?

  An alcohol
• What is the role of hydroxide ions in nucleophilic substitution?

  They act as a nucleophile
• What is the solvent used in the elimination reaction with haloalkanes?

  Ethanol
• What happens to the hydroxide ion in the absence of water?

  It acts as a base
• What must be true about the hydrogen and bromine in the elimination reaction?

  They must be on adjacent carbon atoms
• What are the products of the elimination reaction with 2-bromopropane?

  Propene, potassium bromide, and water
• What is the first step in the mechanism of the elimination reaction?

  A lone pair on oxygen forms a bond to hydrogen
• What happens to the electron pair between hydrogen and carbon during the reaction?

  It forms part of the double bond in the alkene
• What type of fission occurs when the carbon-bromine bond breaks?

  Heterolytic fission
• What does the hydroxide ion remove from the haloalkane?

  A hydrogen ion (proton)
• How does the hydroxide ion act as a base in the elimination reaction?

  By accepting a proton from the haloalkane
• What is the mechanism for the elimination reaction between haloalkanes and hydroxide ions?

  1. Hydroxide ion forms a bond with hydrogen.
  2. Electron pair between hydrogen and carbon moves down.
  3. Electron pair between carbon and bromine moves to bromine.
  4. Bromide ion is formed as the leaving group.
  5. Products: alkene, water, and potassium bromide.
• What are the conditions required for the elimination reaction of haloalkanes?

  • Use potassium hydroxide in ethanol
  • Heat the reaction under reflux
  • Ensure no water is present