Experiment 1 Separation of the components of \"Panacetin\" PDF

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Organic Chem Lab 1
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Lab Report 1 Separating the Components of “Panacetin” Heather Grimes Pre-Lab:

In this experiment, the main objectives were to separate the components of Panacetin and identify the unknown component of our sample. This Introduction:

information would then be used to determine if the sample was counterfeit. This was done by using gravity filtration to separate sucrose, followed by a vacuum filtration of the aqueous layer produced in our separatory funnel, which separated the aspirin component. Finally, by

recrystallization and vacuum filtration, we were able to separate our last component, the unknown. Introduction: In this experiment, the main objective was to separate the components of Panacetin in order to Watchdog drug agency Association for Safe Pharmaceuticals (ASP) suspects a company in the United States is tainting its Panacetin drug, which contains aspirin, sucrose, and acetaminophen, with cheaper chemicals that are similar in structure to acetaminophen. Phenacetin or Acetanilide inhibit pain similarly to acetaminophen but can be harmful to the body. Because it can be harmful, it is illegal in the United States. A sample is to be tested to detect these drugs. In order to determine the concentration of the active ingredients, sucrose must be removed from the mixture with DCM Dichloromethane. The other compounds are miscible in DCM and will leave the sucrose in solid state which can be easily filtered off and weighed. Now the aspirin needs to be converted to a salt, which is immiscible in DCM. After the base, Sodium Bicarbonate, is added the solution will separate into two distinct layers that be separated using a separatory funnel. Once separated, HCl can be added to the aspirin, and it will begin to recrystallize. After the aspirin has precipitated it can be filtered from the solution to dry and be weighted. To remove the unknown from the DCM, the DCM is evaporated off using a rotovap which leaves behind the solid unknown. The mystery powder is separated into three, equal piles for further examination. First is the unknown, the second is added to equal part acetanilide, and the final is added to equal part phenacetin. Knowing the melting points of each substance, allows determination of a physical constant in each pile. This can lead to an understanding of the composition of the unknown substance. Results: Recovered Masses: Aspirin – 0.56g Sucrose – 0.45g Unknown – 0.55g

% Composition of Panacetin: Aspirin – (0.56g/1.56g)x100% = 35.9% Sucrose – (0.45g/1.56g)x100% = 28.8% Unknown – (0.55g/1.56g)x100% = 35.3% % Recovery of Each: Aspirin – (0.56g/2.51g)x100% = 22.3% Sucrose – (0.45g/2.51g)x100% = 17.9% Unknown – (0.55g/2.51g)x100% = 21.9% Melting Range: Unknown – 120°C-130°C Unknown + Acetanilide – 75°C-100°C Unknown + Phenacetin – 120°C-125°C Discussion: A sample is to be tested to detect falsification of the Panacetin drug by trying to identify Phenacetin or Acetanilide. In order to determine the concentration of the active ingredients, sucrose must be removed from the mixture with DCM - Dichloromethane. The other compounds are miscible in DCM and will leave the sucrose in solid state which can be easily filtered off and weighed. Now the aspirin needs to be converted to a salt, which is immiscible in DCM. After the base, Sodium Bicarbonate, is added the solution will separate into two distinct layers that be separated using a separatory funnel. Once separated, HCl can be added to the aspirin, and it will begin to recrystallize. After the aspirin has precipitated it can be filtered from the solution to dry and be weighted. To remove the unknown from the DCM, the DCM is evaporated off using a rotovap which leaves behind the solid unknown. The mystery powder is separated into three, equal piles for further examination. First is the unknown, the second is added to equal part acetanilide, and the final is added to equal part phenacetin. Knowing the melting points of each substance, allows determination of a physical constant in each pile. This can lead to an understanding of the composition of the unknown substance. The expected composition of the panacetin is 40% aspirin, 10% sucrose, and 50% unknown (should be acetaminophen). After conducting the lab, my results showed 28.8% sucrose, 35.9% Aspirin, and 35.3% unknown. The sucrose is approximately 18.2% too high and the Aspirin is 4.1% too low. The unknown was 14.5% too low. I believe there may have been errors in my technique that could have led to different values. Some potential errors could also be in the filtration and separatory procedures. During the experiment with the panacetin, 62.1% of substance was recovered. A cause of error could be due to evaporation of some of the

organic solid in the DCM while it was in the rotovap. Another cause of error could be with the aqueous salt; not all the aspirin salt reacted with the HCl which would be filtered off. In addition, some of the aspirin could have been left with the unknown and later evaporated in the DCM. When filtering off the sucrose, some of the other organic compounds did not entirely dissolve in the DCM, causing a higher amount in the sucrose weight and a lower weight for the Aspirin, this affect would change the compositions. Combines, these errors affected the outcome of the compositions of each component, lowering the yield of panacetin. After conducting thorough analysis of the melting points, I have identified the unknown as phenacetine. To arrive at this conclusion, in the final steps of the experiment three piles were made from the unknown after the DCM was evaporated off. The First pile was mixed together, the seond pile was added to acetanilide, and the third pile was added to phenacetin. Each pile was heated up and the melting points were conducted. The melting point of the unknown was found to be approximately 120°C-130°C which correlates to the known melting point of phenacetin and unknown mixture at about 120°C125°C. The melting point of acetanilide and unknown was 75°C-100°C, not close enough to the unknown melting point to be the identified substance. The melting range of pure phenacetin is approximately 134°C and acetanilide is 114°C. When these compounds are mixed with the unknown they are reduced to approximately 92°C and 104°C respectively. The unknowns melting point is discovered to be about 120°C-130°C, which is closer to melting point of pure Phenacetin. This is supported by further comparing the melting point of the Acetanilide and unknown mixture with just the unknown as they are very different ranges, but the Phenacetin/Unknown mixture melting point was almost identical to the Unknown melting point alone. With this information, we can conclude that the unknown is Phenacetin. Based off my results, I can conclude that the suspicions of the ASP were correct and the drug company has been using cheaper materials to make its panacetin. I arrived at this conclusion after comparing the melting points of the unknown and phenacetin, and the unknown and acetanilide. The unknown’s melting point is almost identical to the unknown mixed with phenacetin. We can also conclude that the percent compositions of the materials listed of the panacetin were different. The sucrose was observed to be in higher concentration and the aspirin was found to be a lower concentration. The concentrations were not in the in the acceptable ranges, 8-12% sucrose, 35-45% Aspirin, and 45-55% unknown. There was some obvious error in the values of the experiment, but I am still confident in the substance identified in the mixture. In conclusion, the company has been using cheaper materials and a higher concentration of sucrose in its drug to cut costs and increase profits. After investigating the panacetin, the unknown

compound used was phenactein, which is a toxic substance, therefore, production of this drug should be stopped immediately. They are also altering the recipe to use higher concentration of cheaper, inactive sucrose, and less of the active aspirin. Questions: 1. A. If I did not stir or shake the mixture fully, the solid would not fully dissolve and this would result in having too low % compositions of aspirin and the because the immiscible sucrose would contain some portions of the unknown and aspirin. This would also potentially cause the sucrose composition to be very high. B. If I failed to mix the aqueous and organic layers, the organic layer would not be completely extracted, causing the percent composition of the aspirin to be lower than expected C. If I mistakenly used the HCl instead of the NaHCO3, the aspirin would not deprotonate into a salt and would still be miscible in the DCM Solution. This means it would not be separated out and would cause the composition percentage of the aspirin to yield too high. 2.

A. If I failed to let the product completely dry, the mass of the unknown and the aspirin would be too high due to the additional weight of water being added. This would cause the yields to be too high. B. If I used enough to crystalize phenacetin but my unknown was acetanilide, the melting points would be incorrect and the percent recovery would be would be too low, completely altering the final results of the experiment. C. If I did not fully extract the Aspirin from the DCM solution, there would be too much aspirin in the organic layer of the solution. This would make it impure and the aspirin percent recovery would be lower, causing the unknown percent recovery to be higher....