Panacetin purportedly includes sucrose, aspirin, and acetaminophen. However, the accuracy of Panacetin’s contents has been called into question by the Association for Safe Pharmaceuticals. Therefore, the lab must discover the accuracy of the ingredients listed on Panacetin’s label. The unknown in this experiment is presumed to be something similar to acetaminophen, such as acetanilide or phenacetin. Recrystallization and melting point temperature were used to help identify the unknown in Panacetin.
Recrystallization removes impurities as a substance goes through physical transformations from a solid to a liquid and back to a solid. As the solid reforms as a crystalline structure, it does so without incorporate any impurities that may have been present in the initial substance. Pure substances have specific melting points that can assist in identification. However, if the substance is not pure, the melting point will be lower than expected. The substance will also have a wider melting point range. To separate the sucrose the lab needed to use ~2.
95 grams of Panacetin and 50 mL of dichloromethane. This mixture was then used extract the sucrose via gravity filtration. To separate the aspirin, the lab used two separate portions of sodium bicarbonate. Two different liquid layers formed, one with an aqueous solution and the other with the organic dichloromethane. The aqueous solution was then separated into one container and the dichloromethane solution into another. The lab then added HCl to the aqueous solution until it was acidic, reaching a pH ? 2.
The aqueous solution was then cooled and the aspirin precipitate was separated. To isolate the unknown, the lab heated the dichloromethane solution to evaporate the solvent until only the unknown remained. It was then heated to remove moisture and weighed. Chemical Reactions Procedure: The procedure in the lab text 1was followed. However, beakers were used instead of flasks in separating the dichloromethane mixture. Furthermore, the separation of aspirin needed to be done twice due to miscommunication in regard to the isolation process for separating the aqueous and organic layers.