4.2.2 haloalkanes

• what reagents are required to make a haloalkane from alcohol?

  sodium halide and concentrated sulfuric acid
• what salts are needed to make haloalkanes

  sodium chloride, sodium bromide, sodium iodide
• nucleophile - electron donor pair
• substitution - replacing a halogen atom for another atom or group of atoms
• describe how alcohols are formed from haloalkanes

  in a nucleophilic substitution reaction using sodium hydroxide
• why dont fluroalkanes hydrolyse

  c - f bond enthalpy too high
• name the mechanism of changing haloalkanes into alcohols

  nucleophilic substitution
• What does CLC mean?

  Chlorofluorocarbon
• What 3 properties of CFC mean they are used as aerosols?

  Low reactivity

  High volatility

  Non toxic
• Why is ozone layer beneficial

  Absorbs harmful UV radiation so UV is reduced at earths surface
• What does HFC mean?

  Hydrofluorocarbon
• When a sodium halide is mixed with concentrated sulfyric acid what is formed?

  NaHSO4 and hydrogen halide
• Silver chloride - white precipitate
• Silver bromide - cream precipitate
• Silver iodide - yellow precipitate
• Aqueous silver nitrate added to haloalkane and halide combines with silver ion to form a silver halide precipitate
• Bond enthalpy decreases down group 7
• Weakest bond hydrolyses the fastest
• Haloalkane to alcohol reagent

  Sodium hydroxide

  Heat under reflux
• Alcohol --> haloalkane

  Concentrated sulfuric acid and sodium halide
• Nucleophile always have a lone pair and act as electron pair donators
• Weaker the bond the easier it is to break and the faster the reaction
• C - F bond too strong don't get substituted
• Make sure to have both the charge and lone pair on the oxygen
• Haloalkane --> alcohol

  Potassium hydroxide
• Haloalkane --> alcohol

  Heat under reflux

  Aqueous solution
• Hydrolysis - splitting of a molecule by a reaction with water
• Water is a poor nucleophile but it can react slowly with haloalkanes in a substitution reaction
• Aqueous silver nitrate he's added halo arcanes to form a silver halide precipitate
• Faster the precipitate is formed the faster the substitution reaction occurs and more reactive the haloalkane
• O2 splits into free radical under UV light
• O + O2 --> O3
• Rate of ozone formation = rate of ozone removal
• O3 + UV light --> O2 + O
• $\cdot$NO + O3 --> NO2 + O2

  NO2 + O$\cdot$ --> O2 + $\cdot$NO
• Cl⋅ + O3 --> ClO⋅ + O2

  ClO$\cdot$ + O --> O2 + Cl$\cdot$
• State two sources of nitrogen oxides in the stratosphere

  thunderstorms

  aircrafts
• haloalkanes ---> alcohols is a nucleophilic substitution