Haloalkanes

• What is the trend in boiling points of haloalkanes as you move down the group?

  Boiling points increase down the group.
• What governs the boiling points of haloalkanes?

  The strength of intermolecular forces governs the boiling points.
• How do intermolecular forces affect boiling points?

  Stronger intermolecular forces result in higher boiling points.
• What happens to the number of electrons as you move down group 7?

  The number of electrons increases down group 7.
• What is the effect of more electrons on van der Waals forces?

  More electrons mean more van der Waals forces between molecules.
• What is the relationship between energy and boiling points in haloalkanes?

  More energy is needed for higher boiling points due to stronger forces.
• Which element is the most electronegative?

  Fluorine is the most electronegative.
• What does high electronegativity indicate about an atom?

  High electronegativity means the atom attracts more electrons.
• What does low electronegativity indicate about an atom?

  Low electronegativity means the atom gives away electrons.
• What scale measures electronegativity of each element?

  The Pauling scale measures electronegativity.
• What is the typical electronegativity range for most metals?

  Most metals have electronegativity < 1.5.
• What is the typical electronegativity range for most nonmetals?

  Most nonmetals have electronegativity > 2.0.
• Why are haloalkanes reactive?

  The difference in electronegativity between δ+ and δ- makes haloalkanes reactive.
• What is a nucleophile?

  A nucleophile is an electron pair donor to somewhere without enough electrons.
• What is nucleophilic substitution?

  Nucleophilic substitution is a reaction where a nucleophile reacts with a polar molecule, removing a functional group and taking its place.
• What do curly arrows denote in nucleophilic substitution reactions?

  Curly arrows denote the movement of a pair of electrons.
• What are the conditions for the reaction of haloalkanes with OH ions?

  • Warm aqueous sodium hydroxide
  • Carried out under reflux
• What is the overall reaction when haloalkanes react with sodium hydroxide?

  • Haloalkane (R-X) + NaOH → Alcohol (R-OH) + NaX
• What is the process called when a nucleophile replaces a halogen in a haloalkane?

  Nucleophilic substitution
• In the reaction with OH⁻ ions, what does the nucleophile attack?

  The 6+ carbon
• What happens to the halogen-carbon bond during nucleophilic substitution with OH⁻ ions?

  The bond breaks and both electrons move to the halogen
• What is formed when a new bond is created between OH⁻ and carbon?

  A new compound is formed
• What are the conditions for the reaction with cyanide ions?

  • Warm ethanolic potassium cyanide
  • Carried out under reflux
• What is formed when cyanide ions react with haloalkanes?

  A nitrile
• In the reaction with CN⁻ ions, what does the nucleophile attack?

  The δ+ carbon
• What happens to the carbon chain when CN⁻ replaces the halogen?

  The carbon chain increases by 1
• What are the conditions for the reaction with ammonia?

  • Heat with ethanolic ammonia
  • Must have excess ammonia
• What is produced when haloalkanes react with ammonia?

  Amines
• What is the trend in reactivity of haloalkanes as you go down the group?

  They become more reactive
• What determines the reactivity of haloalkanes?

  Bond strength/bond enthalpy
• Which haloalkane has the lowest bond enthalpy?

  1. I
• Why are reactions with C-I more reactive?

  Because C-I has the lowest bond enthalpy