• Esters?are compounds with an -COOR functional group and are characterised by their?sweet?and?fruity?smells
• They are prepared from the?condensation?reaction between a?carboxylic acid?and?alcohol?with?concentrated H₂SO₄?as?catalyst
  • This is also called?esterification
• The first part of the ester’s name comes from the alcohol and the second part of the name comes from the carboxylic acid
  • E.g. Propanol and ethanoic acid will give the ester propyl ethanoate

Esters are formed from the condensation reaction between carboxylic acids and alcohols

• Esters can be?hydrolysed?to reform the carboxylic acid and alcohol by either?dilute acid?or?dilute alkali?and?heat
• When an ester is?heated under reflux?with?dilute acid?(eg. sulfuric acid) an equilibrium mixture is established as the reaction is?reversible

Ester hydrolysis by dilute acid is a reversible reaction forming carboxylic acid and alcohol

• However,?heating?the ester?under reflux?with?dilute alkali?(eg. sodium hydroxide) is an?irreversible?reaction as the ester is fully hydrolysed
• This results in the formation of a?sodium?carboxylate?salt which needs further?acidification?to turn into a?carboxylic?acid
  • The sodium carboxylate (-COO-) ion needs to get protonated by an acid (such as HCl) to form the carboxylic acid (-COOH)

Ester hydrolysis by dilute alkali is an irreversible reaction forming a sodium carboxylate salt and alcohol