Abstract Acetylsalicylic acid was prepared using salicylic acid and acetic anhydride. As a result, a white, powdery substance was formed (0. 1931g, percent yield 91. 30%) and was defined by melting point (124. 5 – 134. 5°C) and observation of color change with ferric chloride. Introduction Acetylsalicylic acid (aspirin) is one of the most popular analgesic drugs on the market today. It also acts as an antipyretic and anti-inflammatory drug. Salicylic acid itself was too acidic and irritating to the membranes of the mouth to be taken in its original form, so acetylsalicylic acid was synthesized by a Bayer chemist and sold under the name aspirin.
Procedure See lab notebook. Results and Discussion Mass of Salicylic Acid 0. 2113 g Volume of Acetic Anhydride 0. 480 mL Mass of Acetylsalicylic Acid 0. 1931 g Melting Point of Product 124. 5 – 134. 5°C % Yield 91. 30% Test Tube Observations Control Very light yellow/clear solution Salicylic Acid Deep violet solution Acetylsalicylic Acid Very faint, lavender solution Calculations 0. 2113g x 1mol 138. 1 G SA X1MOL ASA 1MOL SA X180. 2 GASA 1mol ASA =0. 276 g theoretical yield 0. 1931g x 1mol 138. 1 G SA X1MOL ASA 1MOL SA X180.
2 GASA 1mol ASA =0. 252 g actual yield Percent Yield Equation: Actual Yield(g) Theoretical Yield (g)X100 =Percent Yield Actual Percent Yield: 0. 252 g 0. 276 gX100 =91. 30 The experiment yielded a decent amount of acetylsalicylic acid. The initial melting point however was more than 10° lower than the literature melting point. This implies that the substance obtained includes an impurity. During the ferric chloride test, a very faint lavender solution resulted, also confirming that a slight impurity was present.
Some of these impurities could be water (used to rinse the acetylsalicylic acid in the funnel), acetic anhydride, acetic acid or perhaps leftover salicylic acid that was not completely used during the reaction. Suggested improvements include allowing the vacuum to run longer to absorb more of the water used in the filtration stage of the procedure. This would allow a more pure substance.
Conclusion Acetylsalicylic acid was created successfully. The product had a 91. 30% actual percent yield (0. 1931 g) and the melting point range was 124. 5 – 134. 5°C which indicates that some impurity was present. Additionally, by using ferric chloride to test purity, the color results (very faint lavender), confirmed that a slight impurity was present.