• Functional group: carboxylate group,  \(-COOC-\)
  • General formula: \(C_nH_{2n+1}COOC_mH_{2m+1}\), where n = 0,1,2,… and m = 1,2,3,…


Naming ester

  • Ester is produced by combining alcohol with carboxylic acid.
  • There are two parts to naming an ester.
  • The first part is based on the name of the alcohol.
  • The second part is based on the name of the carboxylic acid.
Example - Ethyl butanoate


Steps in naming an ester

  1. Determine the alkyl group of the alcohol chain based on the structural formula or the molecular formula.
  2. Determine the name of the carboxylic acid part.
  3. Change the term ‘oic’ in carboxylic acid to ‘oate’.


Preparation of ethyl ethanoate in laboratory

  • Mixing ethanoic acid with ethanol by reflux reaction.
  • Reflux is needed because ethanol is a volatile solution.
\(CH_3COOH(aq)+ C_2H_5OH(l) \xrightarrow[]{ H_2SO_4}  CH_3COOC_2H_5(aq)+H_2O(l)\)


Physical properties of ethyl ethanoate

  • A colourless solution at room temperature
  • Nice fruity smell
  • Soluble in water


Esterification reaction

  1. Product: ester
  2. Also known as an esterification reaction.
  3. Catalyst: hydrogen ion
  4. Example of esterification reaction of ethanoic acid with ethanol; 
\(CH_3COOH(aq)+ C_2H_5OH(l) \xrightarrow[]{ H_2SO_4}  CH_3COOC_2H_5(aq)+H_2O(l)\)


Uses of ester

  • Food flavourings
  • Perfumes
  • Solvents
  • Detergent
  • Insect repellent
  • Explosives


Natural sources of ester

Flower or fruit



Benzyl ethanoate


Propyl ethanoate


Pentyl propanoate


Methyl benzoate


Ethyl butanoate


3-methylbutyl ethanoate