Melting Point and Solid Acetaminophen

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Acetaminophen

Abstract: The aim of this experiment is to prepare Acetaminophen (p-acetamidophenol), an amide. Acetaminophen will be created by treating an amine (p-aminophenol) with an acetic anhydride. Color impurities present in the solid acetaminophen will be removed and then the decolorized product will be collected on a Büchner funnel for further purification by crystallization. Purity will then be determined by melting point. Introduction: Acetaminophen is commonly used as an analgesic to reduce pain and fever. In this experiment it is prepared by the reaction of p-aminophenol with acetic anhydride, as illustrated below. Results: Isolation of crude acetaminophen The color of the crude product is dirty brown and the crystals were jagged and distinct. weight p-aminophenol:! water:!! ! ! acetic anhydride:! ! theoretical yield:! ! ! ! ! ! ! ! ! ! ! ! ! ! 1.5278g 4.4mL 1.7mL 2.1173g acetaminophen

actual yield:! ! ! ! ! ! percentage yield crude acetaminophen:! !

1.3403g 63.3%

Decolorization of crude acetaminophen The color is now a very pale brown/pink and the crystals have a shimmery look to them, they are still very distinct crystals. weight sodium dithionite:! ! ! water:!! ! ! ! ! weight of purified acetaminophen:!! ! ! ! 2.0213g 15mL 0.90218g

Yield Calculation and Melting-Point Determination weight crystalized acetaminophen:! ! 0.4042g percentage yield:! ! ! ! ! 42.62% melting point crude !! ! ! ! N/A melting point final product:!! ! ! 166-167ºC Analysis:! After final crystallization the color of the product was a very pale pink, almost white, powder. This color and texture change is quite significant from the original brown colored crystals. The original crude product percentage yield (63.3%) was fair. It is unclear why the yield was fair. All the steps were followed according to the procedure. It can be speculated that the removal of the impurities through the heat process caused a lower yield. However, it is unknown how significant the impurities...
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