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1 Acetaminophen Synthesis from P-Aminophenol Tempe PSH 334 Abstract The primary goal of this experiment was to synthesize acetaminophen by reacting p-aminophenol and acetic anhydride in a laboratory setting using several synthesis methods. The primary steps of the experiment included combining the reactants, heating via reflux, crystallizing and recrystallizing the purified result. A recrystallized acetaminophen sample

2 showed a shorter melting point range, indicating higher purity and a percentage yield indicating the procedure was successful. These findings demonstrate the power of organic synthesis methods, highlight the value of purification procedures, and offer valuable insights into organic chemistry. Introduction An over-the-counter pain medication, our primary goal in this project is to create acetaminophen. This synthesis produces acetaminophen via a chemical interaction between p-aminophenol and acetic anhydride (Shen et al., 2023). In addition to this general objective, we seek to acquire practical knowledge of organic synthesis methods and insight into the underlying principles driving chemical reactions within organic chemistry. In organic chemistry, complex molecules are built from simpler starting elements, accomplished by chemical synthesis (Romeo et al., 2023). Breaking and forming covalent bonds in a series of reactions is a common step in the process, which leads to the synthesis of new and more complex structures (Das & Park, 2023). However, it is essential to note that complex syntheses can include many steps and require a great deal of time and effort, as shown by synthesizing molecules like vitamin B12. A theoretical understanding of chemical reactions and the importance of heat in their progression is crucial to the success of our synthesis. Reflux, a type of controlled heating, will be crucial to the success of this experiment by expediting the reaction. Activation energy is needed because of the delicate balancing act of breaking and establishing reactant bonds. In the following sections of this report, we will go into the essential part of the experiment, explaining in detail how various methods were used to collect data (including recrystallization, melting

3 point analysis, and infrared spectroscopy). This experiment makes predictions of the results of these observations and applying theoretical knowledge in the real world is possible. Experimental Approximately 150 mg of p-aminophenol, but the exact value was 0.156 g was indicated to pour into a 5 ml reaction vial. 0.5 ml of distilled water and 0.3 ml of acetic anhydride was added to the vital as well. A magnetic spin vane was placed in the vial and a condenser was attached to the vial. After conducting the steps, the reaction was heated in an aluminum block until reflux and stirred using a magnetic stirrer. Once dissolved a timer was set for twenty minutes. To isolate the product the vial was removed from the heat and it was cooled by room temperature. Once it was cool, the air condenser was removed. After removing the air condenser forceps were used to remove the spin vane and it was rinsed with three drops of distilled water into the reaction vital. While rinsing the spin vane crystals started to form and the vial was placed in an ice bath for immediate crystals form. . Approximately, after 1-2 minutes the vial was removed and quickly filtered to isolate the product. 0.5 ml of distilled water was used to rinse and wash the crystals on the funnel. For fifteen minutes the crystals were dried with air drawn through a filter paper. After fifteen minutes the crystals were weighed and crushed for the recrystallization process. A small portion was put into a melting point capillary. To continue, the crude product was placed into a test tube and the test tube was placed in a beaker with water in the hotplate. Two ml of methanol and two ml of water were used as the 50:50 equation indicated and was added to the test tube. After being boiled and cooled at room temperature crystals started to form. Test tube was placed into an ice bath for completion of

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4 crystals. A previous step conducted above was completed again, crystals were removed and quickly filtered using a filter paper to purify the product on the funnel. After performing the reaction, isolating the product and purifying the product the last step was to characterize. To characterize the product a melting point range was used. Using three melting point capillary tubes: p-aminophenol, the crude, and the recrystallized product. A small portion of the pure product was used to create the final acetaminophen IR Spectrum. Results In the first equation, the moles of P-aminophenol were determined by dividing the experiment amount conducted in the lab (0.156 g) by the molecular weight ( 109.13 g/mol). In the second equation, the moles of acetic anhydride were determined by the experimental volume (0.3 ml) multiplied by the density value (1.08 g/mol) and then divided by the molecular weight ( 102.09 g/mol). P-aminophenol was identified as the limiting reagent. Moles of para-aminophenol = Weight of para-aminophenol (g) = 0.156 g = 0.00142949 mol Molecular Weight (g/mol) 109.13 (g/mol) Moles of acetic anhydride = Weight of acetic anhydride (g) = (1.08 g/mol x 0.3 ml) = Molecular Weight (g/mol) 102.09 (g/mol) 0.00317367 mol Acetic anhydride density = 1.08 g/ml Limiting Reagent for the Reaction: 0.00142949 mol Once crystallization was conducted, the moles of crude product were calculated by the weight of the experimental value (0.046 g) divided by acetaminophen weight (109.13 g.mol).

5 After recrystallization the pure product was calculated by the moles of pure product which is the experimental value ( 0.008 g ) and divided by the molecular weight of acetaminophen (151.16 g/mol). Moles of crude product = Weight of crude product (g) = 0.046 g = 0.00030431 mol Acetaminophen Weight (g/mol) 151.16 (g/mol) Moles of pure product = Weight of pure product (g) = 0.008 g = 0.00005292 mol Acetaminophen Weight (g/mol) 151.16 (g/mol) The percent yield was conducted by dividing the crude product ( 0.00030431 mol ) by the moles of limiting reagent (0.00142949 mol) then multiplying by 100. Repeat for pure product with pure product value (0.00005292 mol). The percent recovery is divided by the moles of pure product and the crude product and then multiplied by 100. Percent Yield of crude product = Moles of crude product x 100 Moles of Limiting Reagent 0.00030431 mol / 0.00142949 mol x 100 = 21.3% Percent Yield of pure product = Moles of pure product x 100 Moles of Limiting Reagent 0.00005292 mol / 0.00142949 mol x 100 = 3.7 % Percent Recovery = Moles of pure product x 100 = 0.00005292 mol x 100 = 17.4 % Moles of crude product 0.00030431 mol Ir spectrum was created for the pure acetaminophen. A table was created with functional groups and frequencies.

6 Figure 1. Table 1. Vibration frequency (cm -1) Functional Group Specific Bond Vibration 3321.32 cm -1 Amine N-H 3158.04 cm -1 Alcohol O-H 1649 cm -1 Carbonyl with amide C=O 1608 cm -1 Aromatic Benzene Table 2 was created as a second component with melting points for characterization. A Digimelt machine was used to find the melting range of the experimental values. Melting Points Name Started Melting Completely Melt P-aminophenol 159.2 C* 177.2 C*

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7 Discussion This study synthesized acetaminophen by reacting p-aminophenol and acetic anhydride in a chemical process. As illustrated below, acetic anhydride was used to replace a hydroxyl group (-OH) of p-aminophenol with the acetyl group (-COCH3). p-aminophenol + acetic anhydride → acetaminophen + acetic acid We used the reflux method, which entails heating a reaction mixture in the presence of an air condenser to speed up the production of acetaminophen. The efficient progression of the reaction and the prevention of reactant loss due to evaporation depended on the presence of reflux. When p-aminophenol, acetic anhydride, and water were combined, a solution was formed as expected. Thanks to a chemical reaction facilitated by the reflux step, Acetaminophen was produced. We then saw the solution cool, leading to the crystallization of the result. The solid acetaminophen was separated through filtration and recrystallized in a hot methanol-water solution (50:50 by volume) for further purification. Melting point analysis and infrared spectroscopy were used to determine the identity of the component in the purified product. We analyzed the data and determined the melting point distribution of crude and recrystallized acetaminophen samples. The results are consistent with expectations, given that Crude 167.1 C* 168.9 C* Pure 167.3 C* 168.5 C*

8 recrystallization is a standard method for removing impurities from organic molecules. The melting point analysis provided a solid basis for judging the product's purity. In addition, we analyzed the pure acetaminophen sample using infrared spectroscopy to determine the presence of unique functional groups. Acetaminophen's amide functional group was represented as peaks in the spectrum. This finding can confirm the success of the synthesis. The detection of peaks indicative of alcohol, aromatic ring, and carbonyl with amide and amine bonds bolstered our inference regarding the product's chemical makeup. The experiment ran smoothly, but it is essential to recognize the possibility of error. Incomplete reactions or the production of unwanted byproducts are always a possibility in chemical synthesis. We suspect that unreacted p-aminophenol or unintended side reactions contributed to the presence of contaminants in the crude product. Human mistakes, such as wrong measurements or carelessness with the materials, may have also impacted results. When evaluating the overall outcome of the experiment, it is crucial to consider these potential causes of mistakes. The acetaminophen synthesis attempted in this experiment was successful, thanks to a chemical reaction and subsequent purifying procedures. The purity and identification of the material were established using melting point analysis and infrared spectroscopy. The outcomes of the experiment were consistent with the hypotheses. However, it is essential to consider the possibility of error. Insights into organic synthesis methods and the practical application of theoretical knowledge were gained through this hands-on experience. Conclusion

9 In conclusion, this study aimed to determine whether or not acetaminophen could be synthesized from p-aminophenol and acetic anhydride. Crystallization, recrystallization, and reflux were all used in the experiment. Recrystallization of the sample indicated product purity, and the percentage yield was sufficient. This experiment effectively showed how organic synthesis methods can be used in real life. The significance of purifying techniques was stressed, and our knowledge of chemical reactions in organic chemistry was broadened. References

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10 Das, G., & Park, S. Y. (2023). Liquid crystalline elastomer actuators with dynamic covalent bonding: Synthesis, alignment, reprogrammability, and self-healing. Current Opinion in Solid State and Materials Science , 27 (3), 101076. Romero, E. O., Saucedo, A. T., Hernández-Meléndez, J. R., Yang, D., Chakrabarty, S., & Narayan, A. R. (2023). Enabling broader adoption of biocatalysis in organic chemistry. JACS Au , 3 (8), 2073-2085. Shen, L., Dong, J., Wen, B., Wen, X., & Li, J. (2023). Facile Synthesis of Hollow Fe3O4-rGO Nanocomposites for the Electrochemical Detection of Acetaminophen. Nanomaterials , 13 (4), 707