Chemistry [[The A2 Practical Exam]] Preparation of Aspirin

[[The preparation of 2-hydroxybenzoic acid]]

1. Set up appartus to heat 30cm3 reaction mixture in a waterbath with the use of a condensor to prevent the loss of product
2. 2g Oil of wintegreen into flask
3. Add 25cm3 of 2 molar sodium hydroxide and antibumping granules
4. Heat over boiling water bath for 30 minutes
5. Pour mixture into beaker surrounded by ice and water
6. Add HCl drop by drop until solution is slightly acidic, stirring at all times
7. Filter product using buchner funnel
8. Wash product with ice water and transfer to weight watch glass
7. Leave to dry over night

[[The preparation of Aspirin]]

1. Use 1g of 2-hydroxybenzoic acid and weigh accuratly
2. Put into pear shaped flask
3. Add 2cm3 ethanoic anhydride and 8 drops of concentrated phosphoric acid. Put condensor on the flask.
4. Warm mixture in hot bath in fume cupboard until all the mixture has disolved and for a further 5 minutes
5. Add 5cm3 of cold water
6. Stand in bath of iced water until ppt is complete - may be necessary to stir vigorously to start ppt process
7. Filter off product using buchner funnel
8. Wash with cold water and transfer to a weighted watch glass
9. Leave to dry over night
10. Weigh product.

[[Recrystallisation]]

1. Dissolve sample in minimum quantity of hot solvent
2. Filter the hot solution using buchner funnel
3. Allow solution to cool slowley
4. Filter cool solution using buchner funnel
5. Wash residue with cold solvent
6. Dry filtrate and Weigh.