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

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.

Preparation of Aspirin (typical A level procedure)

The chemistry used to make aspirin

COH

O

O

COCH3

COH

O

OH

CH3C O

O

C

CH3

O

2-hydroxybenzoic acid

ethanoicanhydride

aspirin

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?

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.)

Preparation of Aspirin (typical A level procedure)

2. Add 4.0cm3 [40 litres] of ethanoic anhydride.(A colourless liquid with a pungent smell).

Temperatureprobe

Preparation of Aspirin (typical A level procedure)

2. Add 4.0cm3 [40 litres] of ethanoic anhydride.(A colourless liquid with a pungent smell).

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.

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.

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.

Preparation of Aspirin (typical A level procedure)

4. When it is cool, add two anti-bumping granules.

5. Heat under reflux for 30 minutes.

Preparation of Aspirin (typical A level procedure)

Heat under reflux for 30 minutes

20

40

60

80

100

120

140

°C

30 60 90 120 150 180Time in minutes

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

Preparation of Aspirin (typical A level procedure)

Heat under reflux for 30 minutes

20

40

60

80

100

120

140

°C

30 60 90 120 150 180Time in minutes

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.

Condenser

8. Filter off the crystals that form. Dry and weigh the product.

Preparation of Aspirin (typical A level procedure)

8. Filter off the crystals that form. Dry and weigh the product.

Preparation of Aspirin (typical A level procedure)

Filter off the crystals that form

Dry and weigh the product