SYNTHESIS OF ASPIRIN
Aim: To prepare a sample of the common analgesic aspirin from salicylic acid and acetic anhydride, test its purity and examine its (IR), nuclear magnetic resonance (NMR) and mass spectra (MS).
Abstract: The goal of this experiment was to synthesize aspirin. In this experiment aspirin, also known as acetylsalicylic acid was synthesized from salicylic acid and acetic anhydride. In the reaction the hydroxyl group on the benzene ring in salicylic acid reacted with acetic anhydride to form an ester functional group. This method of forming acetylsalicylic acid is an esterification reaction. Since this esterification reaction is not spontaneous, sulfuric acid was used as a catalyst to initiate the reaction. After the reaction was complete some unreacted acetic anhydride and salicylic acid was still present in the solution as well as some sulfuric acid, aspirin, and acetic acid. Crystallization, which uses the principle of solubility, was then used to remove most of the impurities and caused the acetylsalicylic acid to precipitate out of the solution. Next, the product was then purified by adding water which further lowered the solubility of acetylsalicylic acid and dissolved some impurities from the aspirin crystals. The aspirin was then isolated from the solution using a vacuum filtration apparatus. The percent yield of the aspirin product was 81.6%. To purify the aspirin product a recrystallization procedure was performed. Next a test was performed to investigate the purity of the aspirin made compared to recrystallized aspirin, commercially available aspirin and salicylic acid as a control. This was done by adding ferric solution to each of