Chemistry Olympiad Training Program
Sec 4/2010
PRACTICAL: HYDROLYSIS OF METHYL SALICYLATE
Name:
AIM
To hydrolyse a sample of methyl salicylate under basic conditions and then synthesise
salicylic acid through the addition of concentrated hydrochloric acid. The salicylic acid is to
be recovered by recrystalllisation.
methyl salicylate
salicylic acid
TECHNIQUES TO BE USED

Refluxing

Recrystallisation

Gravity filtration
BACKGROUND
Esters can be hydrolysed by water under basic or acidic conditions. In basic conditions, the
products of hydrolysis include an alcohol and an organic salt. This salt can be converted to
its corresponding carboxylic acid through acidification.
1
SAFETY CONSIDERATIONS
Care should be taken when handling concentrated hydrochloric acid as it is very corrosive.
Please call your tutor or lab demonstrator before handling the acid. It should also remain in
the fumehood.
Appropriate care should be ensured whenever operating a heating implement such as the
hot plate. Handle all hot glassware carefully by using the oven mitts provided.
PROCEDURE
Reflux of reaction mixture (In groups of four)
1.
2.
3.
4.
Add 3.0 cm3 of methyl salicylate into the 250 cm3 round-bottom flask.
Measure 30 cm3 of 2 mol dm-3 sodium hydroxide and add it to the same round-bottom
flask.
Reflux the mixture until a clear homogeneous solution is obtained.
Allow the solution to cool before transferring the contents into two conical flasks in
equal proportion, one for each pair in the group.
Recrystallization of salicylic acid (In pairs)
5.
6.
7.
8.
Add concentrated hydrochloric acid to the solution until it is completely acidified.
Boil the resulting mixture, adding distilled water until all the precipitate dissolves to give
a clear homogeneous solution.
Allow the solution to cool and crystallize the salicylic acid.
Separate the crystals from the solution by suction filtration.
2
Results, Observations and Calculations
Record all your observations throughout the progress of your experiment.
Given the following information, calculate the percentage yield of salicylic acid obtained in
the experiment.
Mass of pure salicylic acid collected = 2.74 g
Density of methyl salicylate
= 1.17 g dm-3
Mr of methyl salicylate
= 152.1 g mol-1
3