Preparation and Recrystallisation of Aspirin

            
             In this experiment, we conduct the synthesis of aspirin, reinforce the skills of recrystallization and the technique of melting point determination. The procedure goes as follows: Weigh 2.4g of salicylic acid in a conical flask. Then add 6mL of acetic anhydride to the acid. Add 3-4 drops of conc. sulfuric acid and swirl. Heat the mixture in water bath for 10mins. Add a drop of distilled water to decompose the excess acetic anhydride. Add 40mL of cold water. Stir and collect the crude product by suction filtration. .
             Since the crude product is impure, recrystallization is required. Dissolve the crude product in 5mL of ethanol in a conical flask. Further add in 30mL of hot distilled water. Warm until all of the solid dissolves in the solution completely. Allow it to cool. Using the weighed filter paper, obtain the recrystallized product by suction filtration. Transfer the crystals and filter paper onto the weighed watch glass. Dry them in the oven (100°C) for 15mins. Once done, desiccate it for 5mins. Weigh everything and record this weight. The weight is 35.9845g. The weight of the dried, recrystallized aspirin is 1.0071g. The expected yield of aspirin is 3.132g. The percentage yield is 32.2%.
             2. Introduction .
             1. The History of Aspirin.
             Also known as acetylsalicylic acid, was founded nearly in the 1800s. Before the time of Columbus, the Native Americans drank teas made from the bark of the willow to reduce fever. In the early 1800s, the active ingredient in the willow bark was isolated and identified as salicylic acid. After a while, this acid was being synthesised in the laboratory. Acetylsalicylic acid was first discovered by Arthur Eichengruen, Felix Hoffman's supervisor, in the early 1930s. Hoffman was a chemist, working for the Bayer Laboratories in Germany. For many years, it was assumed that it was Hoffman who discovered this acid. But Eichengruen's name was removed due to the fact that he was a Jew and at that very time Nazi Party came to power in Germany.