haloalkane - test for haloalkanes

• hydrolysis of haloalkanes uses aq of hot hydroxide ion and provides nucleophile.
• how do you tect for haloalkanes?

  aqueous silver nitrate and ethanol in a warm water bath
• method for the rate of hydrolysis:

  1. add aqueous AgNO3 in ethanol
  2. in a warm water bath (30-70 degrees)
  3. add same amount of haloalkane
  4. precipitate formed
  5. monitor rate of precipitation formation
• the purpose of water:

  water exists in the equilibrium:

  H2O (l) + H2O (l) <--> H3O+ (aq) + OH- (aq)
• purpose of ethanol:

  acts as a common solvent - ensures the haloalkane and silver nitrate solution mix and react
• results:

  Cl2 - white ppt - most time - AgCl

  Br2 - cream ppt - - AgBr

  I2 - yellow ppt - least time - AgI
• general formula:

  R-X + OH- (aq) --> R-OH (l) + X- (aq)
• general ionic formula:

  Ag+ (aq) + X- (aq) --> AgX (s)
• explain the rate: C-F is slowest because the C-F bond is the strongest