Organic mechanisms

• What is the focus of the AQA A Level Chemistry study material?

  Organic Mechanisms
• What are the two types of fission in reaction mechanisms?

  • Homolytic fission
  • Heterolytic fission
• What occurs during homolytic fission?

  Each atom takes an electron to form radicals
• What happens during heterolytic fission?

  The more electronegative atom takes both electrons
• What is a nucleophile?

  • An electron-rich species
  • Donates a pair of electrons
• What does the term 'nucleophile' mean?

  'Nucleus/positive charge loving'
• What is an electrophile?

  • An electron-deficient species
  • Accepts a pair of electrons
• What does the term 'electrophile' mean?

  'Electron/negative charge loving'
• What are the types of organic reactions?

  • Addition reaction
  • Substitution reaction
  • Elimination reaction
  • Hydrolysis reaction
  • Condensation reaction
• What is an addition reaction?

  Two molecules combine to form a single product
• What is a substitution reaction?

  Replacing an atom or group of atoms
• What is an elimination reaction?

  A small molecule is removed from an organic molecule
• What is a hydrolysis reaction?

  A compound is broken down by water
• What is a condensation reaction?

  Two organic molecules join and eliminate small molecules
• What defines an oxidation reaction?

  Oxygen is added or electrons are removed
• What defines a reduction reaction?

  Oxygen is removed or electrons are added
• What do curly arrows represent in organic reaction mechanisms?

  • Movement of electron pairs
  • Start at a bond or lone pair
  • Point to the electron acceptor
• What should you include in your mechanisms to gain marks?

  Dipoles
• What is a free radical?

  • A species with unpaired electrons
  • Involved in free radical reactions
• What is the first step in a free radical reaction?

  Initiation involves breaking a covalent bond
• What occurs during the propagation step of a free radical reaction?

  Free radicals attack reactant molecules to form more radicals
• What happens in the termination step of a free radical reaction?

  Two free radicals react to form a product
• What is the mechanism of nucleophilic substitution?

  • Nucleophile attacks a carbon atom
  • Partial positive charge on carbon
  • Atom with partial negative charge is replaced
• Why do halogenoalkanes undergo nucleophilic substitution reactions?

  Due to the polar C-X bond
• What is the role of hydroxide ions in nucleophilic substitution?

  They act as better nucleophiles
• What happens in an elimination reaction involving halogenoalkanes?

  A small molecule is removed, forming an alkene
• What is the result of heating halogenoalkanes with ethanolic sodium hydroxide?

  The C-X bond breaks heterolytically
• What is the significance of the C=C double bond in alkenes?

  It is an electron-rich area that reacts readily
• What is the atom economy of electrophilic addition reactions?

  100% atom economy
• What determines the major product in electrophilic addition with asymmetrical alkenes?

  The stability of the carbocation intermediate
• How does the stability of carbocations rank?

  Tertiary > secondary > primary
• What is the major product formed from a secondary carbocation?

  It is more stable than a primary carbocation