Aspirin – Part I II & III: Synthesis, Quantitative & Qualitative Analysis March 30, 2011 Matt Smith Bradley LaBoon Introduction: Aspirin holds a history that dates back to the days of Hippocrates, where he left medical records of using powder from the willow bark to ease headaches, pains and fevers. According to Nick Henderson, Executive Director of the Aspirin Foundation (2009), it was not for years until the salicin within this willow bark was found to be the ingredient to ease such pain. Many scientists extracted this salicin over the years until it was titled the name salicylic acid, in its pure form. It wasn’t until 1900 that aspirin was marketed by Felix Hoffmann who, at the time, worked for Bayer. At first, aspirin was sold as a powder, where as in 1915, the marketed drug switched to a tablet (p.12). This drug has become a valued medical innovation with the help of the salicylic acid ingredient. Aspirin has been found to treat more than just pain. According to Tash Hughes, of Word Constructions, the drug has been proven to reduce swelling/inflammation, reduce the severity of a heat attack, aid recovery after cardiovascular surgery, and even treatment of several rheumatoid diseases (p.23). Many more uses are tested daily for success, as the salicylic acid within the drug proves to aid in more than just headache relief. Due to the fact, however, that aspirin is considered an analgesic, there are possible stomach upsets, and very slight kidney problems. Despite these side effects, aspirin proves to work wonders in the medical field.
Purpose: The purpose of this experiment was to first complete an esterification reaction with salicylic acid and acetic anhydride to produce acetylsalicylic acid in order to observe the purity of an aspirin sample. Several samples will be produced using varied ingredients in order to examine the purity of each, noting how each differs from the commercially produced aspirin samples. From here, several samples of given aspirin will react with an iron (III) chloride solution to determine the purity of the ‘raw’ and re-crystallized experimental samples produced in the previous step. The two commercial aspirin samples will also be observed for purity and the results will be compared to each other.
Method/Procedure: In Part I of the experiment, salicylic acid and acetic anhydride were reacted to produce acetylsalicylic acid, or in other words, aspirin:
To begin this, a 6-gram sample of salicylic acid was recorded and combined with 12 mL of acetic anhydride along with a few drops of sulfuric acid. The reagents were mixed thoroughly and placed in a hot water bath for a time for 20 minutes. From here, the heated reaction solution was allowed to cool to room temperature, and 50 mL of distilled water was added to form crystals before going in an ice bath. The solution then underwent a vacuum filtration in order to separate the formed crystals from the liquid. The crystals were let to dry and ground up before half were placed into a vile labeled ‘raw.’ This is when recrystallization occurs in order to improve the purity of the aspirin sample. The rest of the raw crystals were then dissolved with small amounts of ethanol and then placed in the hot water bath again. Here, the dissolved crystals run through the same crystallization procedure as before. However, this process is not rushed, as a good recrystallization takes time to produce a high quality product. Once finished, these crystals are placed into a vile labeled ‘pure.’ In Part II, a series of three tests were taken to provide information about the presence of impurities. The samples synthesized in Part I, were likely to contain small amounts of impurities, including less in the recrystallized sample. To test other samples, a TLC analysis was taken. Marks were made along the top and bottom of the TLC plate along with 5 marks on the bottom for each of the 5 samples (salicylic acid, new commercial aspirin, old aspirin, raw aspirin, & recrystallized aspirin). A few crystals of salicylic acid were placed on a watch glass along with
