Lab Report 1

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Feb 20, 2024

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Max Barberito 12174194 Separating the Components of Panacetin Introduction Panacetin, an analgesic drug preparation, is commonly made in the US with 200mg aspirin, 250mg acetaminophen, and 50mg of sucrose. However, these ingredients can be tampered with and replaced with similar compounds with similar effects to make for a more profitable product to counterfeiters. Sam Surf, a roving agent who works for the Association for Safe Pharmaceuticals (ASP), purchased some panacetin and discovered some discrepancies on the label and some flaws with the tablet. Because of this, an experiment is being conducted to find out the real ingredients of the panacetin and the composition of the ingredients. This will be done in a multi-stage process to separate each component and find its weight. The experiment will be trying to answer the questions: (1) Is the composition of panacetin as stated on the label correct? (2) What is the identity of the unknown component in panacetin? The panacetin will be mixed with dichloromethane and filtered to separate the sucrose, as it is insoluble in this organic solvent. Then, the filtrate will be extracted with sodium bicarbonate to make two separate layers: an organic one and an aqueous one. The sodium bicarbonate will react with the aspirin to form the salt sodium acetylsalicylate dissolved in water. The unknown will remain in the dichloromethane. These two layers are now separated. Hydrogen chloride is added to the aqueous solution to reform the aspirin, which is then filtered out. The unknown in the dichloromethane is then evaporated to leave only the unknown. Once gathering all of these materials, they will dry and be weighed to solve for the composition. The unknown will be split into fourths then mixed acetanilide in one, phenacetin in another, and the remaining two fourths will be combined. The melting point of these will be tested and recorded to decide what the unknown is made of. Results 1. Component Recovered Mass % Composition % Recovery Aspirin 1.00 g 36.0% 33.3% Sucrose 0.46 g 16.5% 15.3% Unknown 1.32 g 47.5% 44.0% 2. Unknown Unknown+Phenacetin Unknown+Acetinilide Melting Point 84°C-88°C 84°C -87°C 64°C-69°C

Discussion In order to measure and calculate each components composition and make up in the panacetin, they all need to be separated into pure components. The expected composition of panacetin is 40% aspirin, 10% sucrose, and 50% of the unknown. To separate the components, first, one must dissolve most of the panacetin in dichloromethane. The reason for this and the reason for the word “most” is because all of the compounds in panacetin are miscible in dichloromethane except for sucrose, which will be left in its solid state. This solid state is filtered off, dried, and measured. With the addition of sodium bicarbonate to the filtrate, the aspirin will react to form a slat which is now immiscible in dichloromethane. After sodium bicarbonate is added to the solution, two separate layers will form, allowing for a separatory funnel to separate the fluids into different flasks. The aqueous solution containing the aspirin salt will be treated with hydrogen chloride to reform the aspirin and it will begin to recrystallize. Once the aspirin has precipitated, it can be filtered off and weighed. Now, the dichloromethane solution with the unknown in it needs to be separated. The dichloromethane is evaporated off so that the only product left is the unknown. Now all the components are separated. After this part was conducted, the mass fractions came out to be 36.0% aspirin, 16.5% sucrose, and 47.5% unknown. Second, the unknown will be crushed into powder and separated into four equal portions. Two of these portions are combined. The third portion is added to an equal amount of acetanilide. The fourth portion is added to an equal amount of phenacetin. These three samples of powders will be melted to record the melting points of each. The melting points of acetanilide and phenacetin are known due to previous research. The powder sample with a melting point matching that of the pure component closer will reveal the makeup of the unknown. Through comparing the melting points of the powders, phenacetin was the unknown in the sample. The overall percent recovery came out to be 92%, so the amounts recovered and the percent composition of each can be considered accurate. A cause for error could be human error in spilling the samples or inaccurate measurements. Another cause for error could from incorrect stoichiometric amounts of chemicals being added. For example, if not all of the aspirin was reconverted from the salt, the percent recovery would be lower. The most likely reason for error is the combination of components when trying to separate them. This would cause some of the mass of a certain component to be lost and unaccounted for later in the experiment. With a percent recovery of 92%, the percent compositions of each component would not be affected majorly. However, if the percent recovery were lower, the differences in percent compositions could be drastic. Conclusion In conclusion, the Sam was right that the drug companies were putting a toxic chemical, phenacetin, in the panacetin. The make-up of the panacetin did resemble the label, though. The experimental aspirin and sucrose percent compositions were quite close to the percent compositions displayed on the label. Defining the unknown as phenacetin was not too hard, as the melting points of each compound were quite close.

Questions 1. Describe and explain the possible effect on your results of the following experimental errors or variations. In each case, specify the component(s) whose percentage(s) would be too high or too low a. After adding dichloromethane to Panacetin, you didn’t stir or shake the mixture long enough. i. Sucrose’s percentage would be too low b. During the NaHCO3 extraction, you failed to mix the aqueous and organic layers thoroughly i. Both the aspirin and the unknowns would be lower c. You mistakenly extracted the dichloromethane solution with 5% HCl rather than 5% NaHCO3 i. The unknown’s percentage would be much lower 2. Tell how each of the following experimental errors will affect your experimental results (yield, purity, or both) and explain why. a. You failed to dry the product completely. i. This would effect the yield of the products because there would be added weight b. You used enough water to recrystallize phenacetin, but your unknown was acetanilide. i. The yield of the acetanilide will be lower because it has a higher solubility, causing for less precipitate c. When you perform the experiment, you didn’t extract all of the aspirin from the dichloromethane solution. i. This would effect the yield of both the aspirin and the unknown because their weights would be wrong. This would also effect the purity of the unknown because it would be contaminated with aspirin.

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