MECHANISMS AND SUCH

• RADICAL SUBSTITUTION

  3 stages

  • initiation
  • propagation
  • termination
• RADICAL SUBSTITUTION


  Involvement of RADICALS - a species with an unpaired electron
• RADICAL SUBSTITUTION


  Homolytic fission - even splitting of the covalent bond, each atom receives one electron from the bonding pair
• RADICAL SUBSTITUTION


  Reaction - Alkane + halogen -> haloalkane + hydrogen halide

  Conditions - UV light, to overcome activation energy
• RADICAL SUBSTITUTION

  Involvement in break down of ozone
• ELECTROPHILIC ADDITON


  Reaction - Alkene + hydrogen -> alkane

  Conditions - 150 C and a Ni catalyst
• ELECTROPHILIC ADDITION


  Reaction - Alkene + halogen -> di-haloalkane

  Conditions - RTP
• ELECTROPHILIC ADDITION


  Conditions - RTP

  Reaction - Alkene + hydrogen halide -> haloalkane
• ELECTROPHILIC ADDITION

  Reaction - Alkene + water -> alcohol

  Conditions - Steam (water) and H3PO4 catalyst
• ELECTROPHILIC ADDITION


  Electrophile - electron pair acceptor, attracted to an electron dense centre
• ELECTROPHILIC ADDITION

  3 steps - drawn mechanism
• NUCLEOPHILIC SUBSTITUTION


  Reaction - haloalkane + water -> alcohol + hydrogen halide

  or haloalkane + metal hydroxide -> alcohol + salt

  Conditions - Under reflux and an aqueous solution of OH- ions
• HETEROLYTIC FISSION

  Nucleophilic substitution and electrophilic addition
• NUCLEOPHILIC SUBSTITUTION


  Nucleophile - an electron pair donor, has a lone pair of electrons that are attracted to an electron deficient centre
• ELIMINATION OF WATER - DEHYDRATION


  Reaction - alcohol -> alkene + water

  Conditions - reflux, concentrated H2SO4 catalyst
• NUCLEOPHILIC SUBSTITUTION


  Back and forth between alcohols and haloalkanes
• NUCLEOPHILIC SUBSTITUTION


  Reaction - alcohol + hydrogen halide -> haloalkane + water

  Conditions - under reflux
• ESTERIFICATION - CONDENSATION


  Reaction - alcohol + carboxylic acid -> ester + water

  Conditions - reflux, conc. H2SO4 catalyst
• Electrophilic substitution


  • benzene substitutions
  • phenol substitutions
• heterolytic fission

  uneven splitting of the bond - anion and cation formed
• electrophilic substitution

  electrophile - an atom attracted to an electron dense centre to ACCEPT a pair of electrons (to form a new covalent bond)
• Electrophilic substitution - chlorination

  Overall: Cl2 + C6H6 -> C6H5Cl + HCl

  Catalyst: AlCl3
• electron deficient species can be electrophiles
• nucleophiles are negatively charged or have lone pairs on non-metals
• Electrophilic substitution - bromination


  Overall: Br2 + C6H6 -> C6H5Br + HBr

  Catalyst: FeBr3
• Electrophilic substitution - alkylation


  Overall: RCl + C6H6 -> C6H5R + HCl

  Catalyst: AlCl3