4.2.2 haloalkanes

electron pair donator e.g. OH-, NH3,

depends on strength of C - X bond the weaker, the lower the bond enthalpy, the easier to break and the faster the reaction

haloalkane > alcohol reagent: potassium or sodium hydroxide conditions: in aqueous solution, heat under reflux

halide combines with silver ion to form a silver halide precipitate precipitate only forms when halide ion has left the haloalkane and so the rate of formation of precipitate can be used to compare reactivity of different haloalkanes yellow - AgI cream - AgBr white - AgCl (s)

developed for use in aerosols, air conditioning etc low reactivity, volatility and non-toxicity detrimental effect on ozone layer

Uv light causes O2 molecule to split to free radicals O2 + UV > O + P free radicals hit another O2 molecule, forming ozone O + O2 > O3 filter out harmful UV and allow life to survive on earth - UV light increases risk of skin cancer + crop mutation

O3 + UV light > O2 + O rate of formation = rate of removal

catalyse decomposition of ozone due to these reactions as they are regenerated (provide alternative route with lower activation energy) Cl* + O3 > ClO* + O2 ClO* + O* > O2 + Cl* overall: O3 + O* > 2O2