Halogenoalkanes

• Elimination occurs when a halogenoalkane is heated to high temperatures under alcoholic conditions, resulting in the formation of a carbon-carbon double bond (alkene).
• Elimination reactions can only occur from 2o and 3o (tertiary) halogenoalkanes.
• Ozone depletion occurs when CFCs (chloro-fluoro carbons) break down carbon-halogen bonds, forming free radicals that can catalyze ozone depletion.
• Halogenoalkanes contain polar bonds as the halogens are more electronegative than carbon atoms.
• Nucleophilic substitution is a reaction mechanism where nucleophiles attack halogenoalkanes to produce alcohols or amines.
• The greater the Mr of the halogen in the polar bond, the lower the bond enthalpy, meaning it can be broken more easily.
• Nucleophilic substitution reactions can only occur for 1o (primary) and 2o (secondary) halogenoalkanes.
• halogenoalkanes are polar molecules so can experience dipole-dipole forces and van der Waals forces
• as length of the carbon chain increases in halogenoalkanes the strength of van der waals forces increases
• halogenoalkanes are slightly soluble in water and solubility decreases as the carbon chain increases
• elimination

  • two sigma (single) bonds break and one pi (double) bond forms
  • mixture is heated
  • halogenoalkane + nucleophile --> alkene + water