Nucleophilic substitution Haloalkanes ammonia cyanide ions

• What is the role of ammonia in nucleophilic substitution?

  Ammonia acts as a nucleophile
• What happens to the nitrogen atom in ammonia during the reaction?

  The nitrogen donates a lone pair of electrons
• What occurs after the nitrogen atom donates its lone pair of electrons?

  The bond between carbon and bromine breaks
• What is produced at the end of stage one of the reaction with ammonia?

  A positively charged nitrogen atom
• What does a second molecule of ammonia do in the reaction?

  It removes an H+ ion from nitrogen
• What is the product formed from the reaction of ammonia with one bromopropane?

  One Amino propane
• What is formed alongside one Amino propane?

  The ammonium ion NH4+
• What do the ammonium ion and bromide ion form?

  Ammonium bromide
• How is the reaction between Halo alkanes and ammonia carried out?

  By warming in concentrated ammonia solution
• Why is the reaction carried out in a sealed tube?

  To increase pressure and prevent gas escape
• Why is excess ammonia used in the reaction?

  To increase likelihood of reaction with Halo alkane
• What is the role of the cyanide ion in nucleophilic substitution?

  Cyanide ion acts as a nucleophile
• What is the reaction mixture for cyanide ion and Halo alkanes?

  Halo alkane with ethanol and potassium cyanide
• What is the significance of the reaction with cyanide ions?

  It allows increasing the length of carbon chain
• What happens to the carbon atom in the cyanide ion during the reaction?

  The lone pair forms a covalent bond with carbon
• What is produced at the end of the cyanide ion reaction?

  A nitrile molecule and bromide ion
• What are the stages of nucleophilic substitution with ammonia?

  1. Ammonia acts as a nucleophile.
  2. Nitrogen donates a lone pair to carbon.
  3. Carbon-bromine bond breaks.
  4. A positively charged nitrogen is formed.
  5. A second ammonia removes H+ from nitrogen.
  6. One Amino propane and ammonium ion are produced.
• What are the stages of nucleophilic substitution with cyanide ions?

  1. Cyanide ion acts as a nucleophile.
  2. Lone pair on cyanide forms a bond with carbon.
  3. Carbon-bromine bond breaks.
  4. A nitrile molecule and bromide ion are produced.
• What conditions are necessary for the reactions of Halo alkanes with ammonia and cyanide ions?

  • Warm Halo alkane with concentrated ammonia in ethanol
  • Mix Halo alkane with ethanol and potassium cyanide, heat under reflux
• What are the differences in requirements for AQA and Ed XL specifications regarding nucleophilic substitution?

  • AQA: Describe mechanisms for ammonia and cyanide.
  • Ed XL: Describe mechanism for ammonia only.