Pear shaped flask

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Preparation of Aspirin (typical A level procedure)

• Pear shaped flask
• Bunsen burner
• Reflux condenser
• Vacuum filtration

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Preparation of Aspirin (typical A level procedure)
1. Weigh out 2g of 2-hydroxybenzoic acid and
place it in a pear shaped flask. (The starting
material is a fluffy irritant white solid.) 2.
Add 4.0cm3 of ethanoic anhydride. (A
colourless liquid with a pungent smell.) 3. The
reaction mixture will get slightly warm so cool
it by swirling the flask under running water.
4. When it is cool, add two anti-bumping
granules. 5. Heat under reflux for 30
minutes. 6. Cool the mixture. 7. Pour into
100cm3 of cold water containing 10cm3 of dilute
sulphuric acid. Stir and allow the resulting
suspension to stand for 15 minutes. 8. Filter
off the crystals that form. Dry and weigh the
product.
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The chemistry used to make aspirin
ethanoic anhydride
2-hydroxybenzoic acid
aspirin
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Preparation of Aspirin (typical A level procedure)
1. Weigh out 2g of 2-hydroxybenzoic acid and
place it in a pear shaped flask. (The starting
material is a fluffy irritant white solid.) How
would you do this for 20kg - 10,000 times the
scale?
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Preparation of Aspirin (typical A level procedure)
1. Weigh out 2g 20kg of 2-hydroxybenzoic acid
and place it in a pear shaped flask. (The
starting material is an irritant fluffy white
solid.)
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Preparation of Aspirin (typical A level procedure)
2. Add 4.0cm3 40 litres of ethanoic
anhydride. (A colourless liquid with a pungent
smell).
Temperature probe
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Preparation of Aspirin (typical A level procedure)
2. Add 4.0cm3 40 litres of ethanoic
anhydride. (A colourless liquid with a pungent
smell).
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Preparation of Aspirin (typical A level procedure)
3. The reaction mixture will get slightly warm so
cool it by swirling the flask under running water.
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Preparation of Aspirin (typical A level procedure)
3. The reaction mixture will get slightly warm so
cool it by swirling the flask under running water.
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Preparation of Aspirin (typical A level procedure)
3. The reaction mixture will get slightly warm so
cool it by swirling the flask under running water.
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Preparation of Aspirin (typical A level procedure)
4. When it is cool, add two anti-bumping
granules. 5. Heat under reflux for 30 minutes.
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Heat under reflux for 30 minutes
140
120
C
100
80
60
40
20
60
90
120
150
180
30
Time in minutes
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Preparation of Aspirin (typical A level procedure)
5. Heat under reflux for 30 minutes.
Condenser
The maximum transfer of heat from the fluid in
the jacket to the reaction mixture is 2 per
minute
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Heat under reflux for 30 minutes
140
120
C
100
80
60
40
20
60
90
120
150
180
30
Time in minutes
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Preparation of Aspirin (typical A level procedure)
6. Cool the mixture. 7. Pour into 100cm3 1000
litres of cold water containing 10cm3 100
litres of dilute sulphuric acid. Stir and allow
the resulting suspension to stand for 15 minutes.
8. Filter off the crystals that form. Dry and
weigh the product.
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Preparation of Aspirin (typical A level procedure)
8. Filter off the crystals that form. Dry and
weigh the product.
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Filter off the crystals that form
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Dry and weigh the product
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