Esters
5 marks · EasyEsters are made by reacting an alcohol with a carboxylic acid in the presence of an acid catalyst. They are used as flavourings and perfumes.
Name the products when methanol reacts with ethanoic acid under suitable conditions.
Draw the fully displayed structural formula of the ester formed in part (a).
Give one common use of esters.
Esters have a sweet smell. State whether this property makes them suitable for use as solvents, perfumes, or both. Explain your answer.
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(a) methyl ethanoate and water
(b) Fully displayed structural formula of methyl ethanoate: CH3COOCH3 drawn with all bonds shown. · must show all atoms and bonds shown, correct connectivity for methyl ethanoate
(c) Used as a flavouring OR perfume
(d) Both – esters are used as solvents and in perfumes because their sweet smell makes them suitable for perfumes, and some are volatile liquids used as solvents. · must show mention perfumes (smell), mention solvents (volatility)
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Marking points
B1 (a) · 1 mark · Correctly names methyl ethanoate and water as the products
B2 (b) · 1 mark · Correctly draws the structure of methyl ethanoate
B3 (b) · 1 mark · All atoms and all bonds shown
B4 (c) · 1 mark · States a common use of esters (e.g. flavouring, perfume)
B5 (d) · 1 mark · Mentions both solvents and perfumes OR explains the sweet smell for perfumes/volatility for solvents
Worked solution
(a) The products are methyl ethanoate and water.
(b) The fully displayed formula is as below.
The drawing should show all atoms and bonds:
H H | | H—C—C—O—C—H | | | H O H || O
(c) Common use: "Esters are used as food flavourings or perfumes."
(d) Suitable for both perfumes and solvents. Perfume: because of their sweet smell. Some esters are volatile and can be used as solvents.