7.3.2 Esters

Question 1

Naming Esters

Answer 1

Question 2

Uses of Esters

Answer 2

• Fragrances (fruity smell)
• Flavourings
• Plasticisers (increase flexibility of polymers, penetrates layers between polymer chains, reduces polar bonds by increasing distance between them, allowing chains to slide over each other)
• Solvents (cheap, low volatility, low toxicity)

Question 3

What esters are naturally occurring?

Answer 3

• Triglycerides in animal fat and olive oil
• 1 glycerol molecule and 3 fatty acids

Question 4

How can esters be used to test for alcohols?

Answer 4

• Unknown substance warmed with carboxylic acid in presence of concentrated sulphuric acid
• Excess acid neutralised by adding warm aqueous sodium carbonate
• Pungent vinegary smell should go away
• If remaining mixture has sweet smell, it is an ester, proving presence of an alcohol
• Warm solution causes ester to evaporate so sweet smell is easily detected