haloalkanes

• haloalkanes + alcohols: nucleophilic substitution
• difference in electronegativity causes a dipole
• all halogens are more reactive than carbon
• CH3Br (l) + OH- (aq) -> CH3OH (l) +Br- (aq)

  name: nucleophilic substitution

  conditions: heat under reflux

  reagent: hot aqueous sodium hydroxide
• no intermediate stage in nucleophilic reaction as it's too quick
• depletion of the o-zone layer:

  • increased UV rays here means more skin cancer
  • CFCs (chlorofluorocarbons)
• CFCs (chlorofluorocarbons) are a family of organic compounds which have low reactivity, high volatility and are non-toxic.
• radicals catalyse the breakdown of the o zone layer
• formula of the breakdown of the o-zone layer:

  .Cl + O3 --> .ClO + O2

  .ClO + O --> .Cl + O2

  overall: O + O3 --> 2O2
• how many o-zone molecules does one radical destroy?

  100,000 molecules
• nitrogen monoxide released from aircrafts and cars:

  NO + O3 --> NO2 +O2

  NO2 + O --> NO + O2

  overall: O3 + O --> 2O2
• CFCs are still a problem because:

  • high residence time
  • caused by lack of reactivity (inert)/ slow diffusion
  • developing nations still used CFCs