Properties of alcohols

• Methanol is used as a high-performance fuel because of its efficient combustion.

  It is also an important chemical feedstock - the staring material in many industrial syntheses.

  it can be converted into polymers, paints, solvents, insulation, adhesives, and many other useful products
• When comparing alcohols with alkanes of the same chain length, the alcohol is less volatile, has higher melting point, and greater water solubility than the alkane.

  The differences become smaller as the chain length increases
• The reasons for the differences between alcohols and alkanes:

  • Alkanes have non-polar bonds because carbon and hydrogen have very similar electronegativity
  • Alkanes = non-polar
  • The intermolecular forces between non-polar molecules are very weak London forces
  • Alcohols have a polar O-H bond because of the difference in negativity between oxygen an hydrogen atoms
  • Alcohols = polar
  • Alcohol intermolecular forces will be very week London forces and much stronger hydrogen bonds between the polar O-H groups
• Due to hydrogen bonding in alcohols, they have a lower volatility than alkanes of the same chain length
• Alcohols are soluble in water because their -OH allows them to form hydrogen bonds with the water molecules.

  Alkanes are insoluble because they are non-polar so cannot form hydrogen bonds with the water.
• In alcohols, as the carbon chain increases in length, the influence of the -OH becomes relatively smaller so the solubility decreases
• In a primary alcohol, the -OH group is attached to a carbon atom that is attached to two hydrogen atoms and one alkyl group. Methanol is an exception because even though the carbon is attached to three hydrogens and no alkyl groups, it is still classified as a primary alcohol
• In a secondary alcohol, the -OH group is attached to a carbon atom that is attached to one hydrogen atom and two alkyl groups
• In a tertiary alcohol, the -OH group is attached to a carbon atom that is attached to three alkyl groups