SCH4U: Preparation of Esters Lab
Introduction:
Esters are responsible for the “fruity” odours and flavours of many naturally occurring products.
Chemists can reproduce these odours or flavours in the lab by mixing the right alcohol and carboxylic
acid together; thus, producing “artificial” or “synthetic” versions of these naturally occurring compounds.
In this lab activity you will create a number of different esters and attempt to identify the odour of each
ester created.
Materials:
Alcohols
A. Methanol
B. Ethanol
C. 1-propanol
D. 2-propanol
E. Isobutyl
F. Isopentyl
G. Isoamyl
H. 1-octanol
Acids
W. Salicylic acid
X. Acetic acid (ethanoic)
Procedure:
1)
Set up a 400mL beaker, half full with water, on a hot plate to act as a hot bath (75o-80oC) (Do
not allow water to boil).
2)
Obtain two clean test tubes. Into one test tube add approximately 1mL of the desired alcohol;
into the second test tube add approximately 1mL of the desired carboxylic acid. Carefully, waft
the vapours of each tube towards your nose and record the odour of each reactant.
3)
Mix the contents of the two test tubes together. Using a dropper add 5 drops of concentrated
sulphuric acid to the mixture. Carefully, mix the solution.
4)
Place the test tube containing the reactants into the hot bath for about 5 minutes. Do not let the
water or the contents of the test tube boil.
5)
Remove the test tube from the water bath and carefully waft the vapours towards your nose. If
6)
7)
8)
you have trouble detecting the odour of the ester follow the next step.
Add approximately 20mL of warm water to a 250mL beaker. Pour the contents of your test tube
into the beaker containing warm water.* Carefully, waft the vapours towards your nose and
smell the odour emanating from the beaker.
Name the ester and describe its odour.
Discard the contents of your beaker into the organic waste jar.
** Why would putting the ester reaction mixture in water help us smell the ester?
Observations
Ester #1
Alcohol
Carboxylic Acid
Ester
Odour
Using structural formula, show the reaction that occurred:
Ester #2
Alcohol
Carboxylic Acid
Ester
Odour
Using structural formula, show the reaction that occurred:
Ester #3
Alcohol
Carboxylic Acid
Ester
Odour
Using structural formula, show the reaction that occurred:
Ester #4
Alcohol
Carboxylic Acid
Ester
Odour
Using structural formula, show the reaction that occurred:
Ester #5
Alcohol
Carboxylic Acid
Odour
Using structural formula, show the reaction that occurred:
Ester
Teacher Key
Alcohol
Acid
Ester produced
Smell
Methanol
Butanoic acid
Methyl butanoate
Pineapple
Methanol
Benzoic acid
Methyl benzoate
Marzipan
Methanol
Salicylic acid
Methyl salicylate
Wintergreen
Ethanol
Methanoic acid
Ethyl methanoate
Raspberry/rum
Ethanol
Ethanoic acid
Ethyl ethanoate
Pear drops/nail-varnish
remover
Ethanol
Butanoic acid
Ethyl butanoate
Pineapple
Propan-1-ol
Ethanoic acid
Propyl ethanoate
Pear
Pentan-1-ol
Ethanoic acid
Pentyl ethanoate
Banana
Pentan-1-ol
Butanoic acid
Pentyl butanoate
Apricot/pear
Pentan-1-ol
Pentanoic acid
Pentyl pentanoate
(Pine)apple
3-methylbutan-1-ol
Ethanoic acid
(isoamyl alcohol)
3-methylbutyl ethanoate Banana/bee alarm pheromone
Octan-1-ol
Ethanoic acid
Octyl ethanoate
Orange
Phenylmethanol
(benzyl alcohol)
Ethanoic acid
Benzyl ethanoate
Peach