Synthesis of Aspirin

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In this experiment, acetylsalicylic acid was synthesized from the acidification of salicylic acid and acetic anhydride. The objective was to convert a specific amount of salicylic acid into the same amount of aspirin that was high in purity. Furthermore, the other objectives were to enable students to conduct the synthesis of aspirin, reinforce skills or recrystallisation and the technique of melting point determination. The amount of each compound should be the same because there is a 1:1 ratio between them. The purity of the synthesized aspirin was measured by determining its melting point and percent yield. Soluble impurities increase the range over which a compound melts and often decreases its overall melting point
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A solvent suitable for this recrystallization process would be a mixture of ethanol and water. The crude product was dissolved in approximately 5ml of ethanol in a 100ml conical flask and heated on a hot plate. To the solution, 30ml of hot distilled water was added in. The solution was then warmed till all solid has dissolved. The solution was allowed to cool. A clean, dry watch glass together with a filter paper was weighed and the weight was recorded. The recrystallised product was obtained by suction filtration using the weighed filter paper. The crystals and filter paper was transferred onto the weighed watch glass and dried in to the oven (100°C) for 15 to 20 minutes. The crystals, filter paper and watch glass are then placed in desiccators for 5 to 10 minutes. The dried crystals, together with the filter paper and watch glass were weighed. The weight was recorded and the weight of dried, recrystallised aspirin was calculated. The expected yield of aspirin was calculated from the amount of salicylic acid used. The percentage yield of dried, recrystallised aspirin was also calculated. The melting point of aspirin was determined.
Mass of salicylic acid
Mass of filter paper and watch glass
Mass of dried, recrystallised aspirin, filter paper and watch glass
Mass of dried, recrystallised aspirin Mass of dried, recrystallized aspirin, filter paper and watch glass Mass of filter paper and watch glass

Percent yield
Number of moles of

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