Synthesis of Aspirin
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In this experiment, the Oil of Wintergreen is put into an Erlenmeyer flask containing sodium hydroxide to create sodium salicylate. The solution is then refluxed which means that the solution will be boiled in a base, then condensed in a condenser. This replaces the carbon on the ester at carbon 1, with an oxygen atom which will have an ionic bond with a sodium anion. This yields sodium salicylate which will be acidified in methanol (CH3OH) which will remove the sodium bonded to the oxygen, and switch it to a hydrogen atom bonded to the oxygen, making an alcohol group. This new product is salicylic acid. Acetic anhydride is added to the salicylic acid to add an acetyl group to carbon 2 which will create acetylsalicylic acid (aspirin). Experimental Procedure: See Attached Papers
Chemicals used in Experiment
Chemical:Amount Used (mL)
Oil of Wintergreen4.3
The oil of Wintergreen is clear until the sodium hydroxide (NaOH) is added. The solution then gets foggy/cloudy and white snowlike precipitate is floating within the solution. Heat is added along with a stir bar. The stir bar starts stirring at minute 7. It begins to dissolve the white powder as it spins. At minute 26 the solution becomes clear with barely any flakes left. Sulfuric acid is then added and white flakes are formed. More acid is added until the pH paper turns red. The round bottom is filled with white precipitate. The precipitate is put onto a hirsh funnel that uses vacuum filtration to isolate the precipitate.
The product is then added to a beaker with D.I water and heated. It’s put through the hirsh funnel . 3.68 grams of salicylic acid is recovered. The melting point is tested to compare to a perfect sample. The melting point is 146C0. The product is dried and added to a beaker with D.I. water and 10mL of acetic anhydride and 20 drops of concentrated sulfuric acid. This product is chilled to produce crystals. Its then filtered using a hirsh filter using vacuum filtration. Recrystallized and filtered one last time. The product is now acetylsalicylic acid (aspirin).
Calculations and Yield Data: See attached Papers
The purpose of the experiment was to make acetylsalicylic acid (aspirin) from methyl salicylate (oil of wintergreen). The amount of acetylsalicylic acid recovered was 1.7 grams. The percent yield is 104.94% of what the theoretical yield was. This can be calculated using the yields from Oil of wintergreen (methyl salicylate) to salicylic acid, which was 98.66%. Also by using the yield from the salicylic acid to the acetylsalicylic acid (aspirin) which was 106.25%. Sources of error are that during transfer of our product from filter paper to a watch glass, some product was dropped and not all of it was recoverable. Another source of error is that while transferring product from the filter paper to either a watch glass, or beaker, or round bottom, product stuck to the filter paper and not all of the product was able to be recovered.