Halogenoalkanes

• What is a halogenoalkane?

  Halogenoalkane is a compound containing a halogen atom bonded to an alkane chain.
• Are halogenoalkanes soluble in water?

  Insoluble

  C-H bonds are non-polar
• Do halogenoalkanes have polar bonds?

  Yes polar as halogen has a higher electronegativity than C

  (Halogen is negative Carbon is positive)
• Which intermolecular forces do halogenoalkanes have?

  Permanent dipole-dipole and van der Waals forces of attraction
• When do halogenoalkanes have higher boiling points?

  • Increase Carbon chain length
  • Halogen further down group 7
• How would the mass of a halogenoalkane compare with the mass of an alkane of the same chain length?

  Halogenoalkane = Greater mass

  As the mass of halogen > mass of H
• What factor is the most important factor in determining their reactivity?

  Carbon-halogen bond enthalpy
• Order of reactivity of halogenoalkanes?

  Reactivity increases down the group
• What is a nucleophile?

  A negatively charged ion with a lone pair of electrons

  It can be donated to an electron deficient atom
• What is nucleophilic substitution?

  A reaction where a nucleophile donates a lone pair of electrons to C+ atom

  The negative atom leaves the molecule (replaced by nucleophile)
• Draw the mechanism for the reaction of bromoethane with NH3

  :

  
• Draw the mechanism for the reaction of bromoethane with NaOH in ethanol

  :

  
• What are CFCs?

  Chlorine-Fluoro-carbons

  • Halogenoalkanes containing C F CL and no (H)
• What are the problems with CFSs?

  • Unreactive under normal conditions
  • But they catalyse the breakdown of ozone in the atmosphere via free radical substitution
• What are the conditions needed for the elimination reaction of halogenoalkanes?

  NaOH or KOH dissolved in ethanol

  Heated
• What is formed in the elimination reaction of halogenoalkanes?

  • Alkene
  • Water
  • Halogen ion
• Give 3 nucleophiles?

  :NH3

  :OH-

  :CN-