17.1    Introduction to Alcohols

What are alcohols?

• Alcohols are compounds in which one or more hydrogen atoms in an alkane have been replaced by an -OH group

• Alcohols can be classified as primary, secondary or tertiary depending on the number of alkyl groups(R groups) attached to the carbon atom holding the -OH group.

• Some examples of alcohols:

Physical properties of alcohols

• i) Alcohols are soluble in water because they can form hydrogen bonds with water  molecules.ii)However, the solubility decreases as the number of carbon atoms This is because the presence of long hydrocarbon tail disrupts the effectiveness of  hydrogen bonding.

• 1. Alcohols have higher boiling points than the alkanes with similar Mr due to the presence of intermolecular hydrogen bonding in addition of van der Waals’ forces of attraction.
  2. The boiling point increases as the number of carbon atoms increases. This is because there are more electrons, hence more temporary dipoles can be set More energy is required to overcome these forces.