Esters

An ester is a carboxylic acid derivative.
 Naming Ester: Put alcohol part first and then acid.
 Ester commonly used for perfumes or flavourings as they have a fruity smell.
 1) Esterification: Esterification is reaction of an alcohol with carboxylic acid to form
a water. Alcohol warmed with carboxylic acid, with concentrated sulfuric acid- an acid catalyst.
Can use this to test for alcohol- will produce sweet smelling ester. May be able to use other acid
catalysts such as H3PO4.
– If two OH groups, do two esters.
 Making Esters Experiment: Add alcohol and carboxylic acid. Add concentrated sulfuric acid.
Place boiling tube in beaker of hot water. Put sodium carbonate, a base, which removes
carboxylic acid not reacted. Will see oily drops of ester on top of water.

Hydrolysis: Hydrolysis is the breaking of a bond in the presence of water or in aqueous solution.
Esters can be hydrolysed by aqueous acid or alkali…
 2) Acid Hydrolysis: Acid hydrolysis is reverse of esterification. Ester is heated
under reflex with water and catalyst dilute aqueous acid. Forms carboxylic acid and alcohol.
 3) Alkaline Hydrolysis: Aka saponification. Irreversible. Ester heated under
reflux with aqueous hydroxide ions. Forms carboxylate ion and alcohol.
 If aqueous sodium hydroxide is the alkali, salt sodium ethanoate CH3COO-Na+ produced instead
of carboxylate ion.