Laboratory Report
Organic chemistry practical course (OCP1)
HS 07/08
30.10.2007
Lorenz Schwarzer
D-Biol
Assistant: Zhu Liang
Synthesis of Oil of wintergreen
(Methyl salicylate)
O
O
CH3
OH
Method
Acid-catalyzed esterification of carboxylic acid:
Esterification of salicylic acid with methanol to methyl salicylate, catalyzed by sulfuric
acid.
Reaction equation
O
O
O
OH
OH
H+
+
CH3
OH
salicylic acid
CH3
OH
methanol
methyl salicylate
Mechanism
H
O
O
H
OH
O
H
H
OH
O
OH
H
OH
OH
H
H
O
H
H
O
O
O
O
O
H
O
O
H
OH
OH
2
OH
Physical properties of the substances
Salicylic acid
O
OH
Molar weight
Density
Melting point
Boiling point
R-Phrases
138,12 g/mol
1,44 g/ml
158-161
°C
°C
R22 Harmful if swallowed,
R37/38 Irritating to respiratory system
and skin
R41 Risk of serious damage to the
eyes.
S26 In case of contact with eyes rinse
and seek medical advice.
S39 Wear eye/face protection
OH
S-Phrases
Methanol
Molar weight
Density
Melting point
Boiling point
R-Phrases
OH
R11
R23
R25
S2
S7
S16
CH3
S-Phrases
S24
32,04 g/mol
0.79 g/ml
°C
64,4-64,8
°C
Highly flammable.
Toxic by inhalation.
Toxic if swallowed.
Keep out of the reach of children.
Keep container tightly closed
Keep away from sources of
ignition.
Avoid contact with skin.
Sulfuric acid (H2SO4)
HO
O
Molar weight
Density
Melting point
Boiling point
R-Phrases
S-Phrases
98,07 g/mol
1.84 g/ml
10
°C
338
°C
R35 Causes severe burns
S1/2 Keep locked up and out of the
reach of children
S26 In case of contact with eyes, rinse
immediately with plenty of water
and seek medical advice.
S30 Never add water to this product
S45 In case of accident or if you feel
unwell, seek medical advice
immediately
S
O
OH
3
Methylene chloride
Molar weight
Density
Melting point
Boiling point
R-Phrases
Cl
H
Cl
R20
R40
H
S-Phrases
S24
84,93
1.33
40-41
Harmful by inhalation.
Limited evidence of a
carcinogenic effect.
Avoid contact with skin.
g/mol
g/ml
°C
°C
Methyl salicylate
Molar weight
Density
Melting point
Boiling point
R-Phrases
O
O
R22
R36
S24
S26
CH3
OH
S-Phrases
152,14 g/mol
1,18 g/ml
-8
°C
222
°C
Harmful if swallowed,
Irritating to eyes
Avoid contact with skin.
In case of contact with eyes rinse
and seek medical advice.
Educts
Substance
Salicylic acid
Methanol
Sulfuric acid
Amount
Molar amount
g
4.73
~14
9.2
mol
0.0342
~0.437
0.0938
Volume
ml
~18
5
Experimental accomplishment
1. Salicylic acid and methanol were put a 100ml round bottom flask. With heating
and swirling, the salicylic acid was dissolved. Sulfuric acid was added
dropwise – some white precipitate was visible. A boiling chip was added and
the mixture was boiled at 60°C for 1h under reflux.
2. The solution was cooled to room temperature, transferred to a separatory
funnel and 15ml methylene chloride and 10ml distilled water was added (the
solution was smelling already). The lower layer (methylene chloride) was
saved. This step was repeated one time.
3. The methylen chloride layer was washed with 15ml distilled water, the
aqueous layer was discarded.
4. The organic layer was washed with NaHCO3.
5. The methylen chloride and the remaining water were separated by distillation
(small distill apparatus).
6. The product was weighted and the refractive index and the infrared spectrum
were measured.
4
Experimental setup
Reflux condenser
Thermometer
Oilbath
67
4 5
8
3
11
9
21
4 5
3
2
1
67
8
9
1
0
Heating apparatus
Separation funnel
Thermometer
Condenser
Oilbath
67
45
8
3
11 9
21
4 5
3
2
1
67
8
9
1
0
Distillation Apparatus
5
Results
Yield:
Amount of salicylic acid:
Amount of the product:
Yield:
4.73 g
3.93 g
83 %
Refractive index: Token:
Methyl salicylate (lit.):
1.528
1.535-1.538
IR-Spectrum-bands [cm-1]
O-H stretch (alcohols)
O-H stretch (carboxylic acids)
C=O stretch (esters)
3200-3500
2500-3600
1735-1750
With the aid of the comparisons of the token IR-spectrum with the reference
spectrum, the product can be identified as methyl salicylate.
The token refractive index confirms this result.
IR-Spectrum of the Product
6
Reference IR-spectrum of methyl salicylate (red: IR of the Product)
Literature



http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_index.cgi?lang=eng
http://en.wikipedia.org
http://www.discoverygate.com
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