Experiment_7 - Experiment 7 Williamson Ether Synthesis of...

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Experiment 7: Williamson Ether Synthesis of Phenacetin The process of displacement of a halide (RX where X = Cl, Br, I) by an alkoxide anion (RO-) to form an ether is called a Williamson ether synthesis. The principal starting material of this reaction is N-(4-hydroxyphenyl)- acetamide, a compound also known as acetaminophen. It is an analgesic (a medication that reduces or eliminates pain) and antipyretic (a medication that reduces fever) and is found in many over-the-counter drugs. For example, it is the active ingredient of many Tylenol® products. The principal product phenacetin was once the active ingredi- ent of several analgesic and antipyretic Excedrin® medications. Interestingly, phenacetin is converted in the human body to acetaminophen, which is the active agent. The phenol of acetaminophen is a relatively poor nucleophile. However, the presence of the base (potassium carbonate) causes the generation of the conjugate base of aceta- minophen. This new species is called a phenoxide anion, and it serves as a more potent nucleophile than the starting alcohol. The phenoxide anion then displaces iodide via backside attack in a one-step process involving a negatively charged pentavalent interme- diate. The rate of the reaction depends on the concentration of both the phenoxide anion and the iodoethane; so the reaction is described as S N 2 (substitution nucleophilic bimolecular). please regenerate this completed table in part 1 of your notebook reagents Phenol potassium carbonate MEK ethyl iodide ethylated phenol phenacetin formula equiv 1 1.16 1.5 eq 1 MW 151.16 mg/mmol 138.21 mg/mmol 155.97 mg/mmol 179.22 mg/mmol den 1950 mg/mL vol 1.0 mL 0.08 mL (4 drops) mass 100 mg 180 mg 156 mg 118.56 mg mmol. 0.66 mmol
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This note was uploaded on 08/14/2010 for the course BIO 2010 taught by Professor Le during the Summer '10 term at UCSB.

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Experiment_7 - Experiment 7 Williamson Ether Synthesis of...

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