Halogenoalkanes

Structure

• Halogenoalkanes are reactive

• Due to difference in polarity of the C-Cl or Br

Nucleophile

• A negatively charged ion or electronegative atom

• Has a lone pair

• Looking for a positive centre

  • e.g. :OH-, :NH3, :-CN

Nucleophilic substitution

• KOH aqueous and cold, :OH acts as a nucleophile → Alcohol

  • Will also produce alkenes in small amounts

• KCN dissolved in ethanol → Nitrile, e.g. pentanenitrile

  • Can be reduced to an amine or hydrolysed to a carboxylic acid

• NH4 dissolved in ethanol in excess and concentrated → Amine

Elimination

• KOH, hot and dissolved in ethanol, :OH acts as a base → Alkene

Depletion of ozone

• Prevents harmful UV rays getting through to Earth

• CFC bad, chlorofluorocarbons were released into the atmosphere

• Cl-Cl bonds were broken down UV rays