Williamson ether synthesis of phenacetin. Basai Lab 10 Williamson Ether Synthesis 2022-10-08

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The Williamson ether synthesis is a chemical reaction used to synthesize ethers, which are compounds containing an oxygen atom bonded to two carbon atoms. One of the most well-known examples of this reaction is the synthesis of phenacetin, a pain reliever that was once widely used but has since been discontinued due to its potential side effects.

The Williamson ether synthesis involves the reaction of an alkoxide ion with an alkyl halide, resulting in the formation of an ether. In the case of phenacetin, the starting materials are acetaminophen (analgesic) and ethyl bromide. The reaction is typically carried out in the presence of a base, such as sodium hydroxide, to facilitate the formation of the alkoxide ion.

The reaction begins with the protonation of the acetaminophen molecule, which is facilitated by the presence of the base. This generates the acetaminophen protonated form, which is more reactive than the neutral form. The ethyl bromide then reacts with the acetaminophen protonated form to form the intermediate compound, ethyl acetaminophenium bromide.

The intermediate compound then undergoes deprotonation, resulting in the formation of the ether, phenacetin. The deprotonation step is facilitated by the presence of the base, which acts as a proton acceptor. The reaction can be represented by the following equation:

Acetaminophen + Ethyl bromide + NaOH -> Phenacetin + NaBr

The Williamson ether synthesis is a useful method for synthesizing ethers, and it has been widely applied in the synthesis of various compounds, including pharmaceuticals, fragrances, and dyes. However, the reaction can also produce impurities, and the use of alkyl halides as starting materials can be hazardous due to their potential to form explosive compounds.

In conclusion, the Williamson ether synthesis is a chemical reaction used to synthesize ethers, including phenacetin. While this reaction is useful, it can also produce impurities and the use of alkyl halides as starting materials can be hazardous.

Exp 6a

williamson ether synthesis of phenacetin

This image is from the UIC Organic Chemistry Lab Manual, pg. The percent yield of the reaction was calculated to be This is extremely low, and there are several reasons for this poor result. Overall, the experiment was very insightful and introduced us to the rotary evaporation device. Followed by 1 mL of methanol through the top of the alumina. The best bet as to where some mixture was lost was when the reflux apparatus was in use which means some of the mixture may have boiled into the hempel column which ultimately ends in its loss. Alkyl halides or tosylates react to ethers by forming alkoxy ions. Due to the dangers of iodoethane, 1 mL is measured under the hood and placed into the flask.

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lab report 10

williamson ether synthesis of phenacetin

Taking the liquid from the filtration flask a TLC plate can be completed on the reaction mixture. Acetaminophen consists of hydroxyl group which is more polar than phenacetin consisting of ethoxide group. Lab Manuel For this particular lab, it revolved around ethers. By working in groups of two we were able to complete both methods of synthesis routes. To finally verify the correct compound was found melting point analysis and IR spectroscopy were used. The mechanism of the reaction is as follows: In this lab, a conical vial was first prepared containing methyl ethyl ketone MEK , acetaminophen, K 2 CO 3 , ethyl iodide, and a spin vane. K2CO3 is anhydrous, and the Williamson ether synthesis majorly involves the removal of a proton from an alcohol using an SN2 nucleophilic reaction.

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Basai Lab 10 Williamson Ether Synthesis

williamson ether synthesis of phenacetin

Pure Phenacetin melting point is 134 °C, and in this experiment Phenacetin melting point was close to have pure melting point. Slightly less than half of product was lost from 0. The remaining solvent was then evaporated in a preheated 50 C water bath and gentle air stream until 1 mL was left. After the solvent finishes traveling up the TLC plate, the solvent line is marked. A pencil is used to mark the starting point of the sample then again to mark the ending point of the mobile phase and the spots of the separated sample. The melting point range of crude acetaminophen ranged from 166. There are little to no spectra, tables, or calculations.

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What is the synthesis of phenacetin?

williamson ether synthesis of phenacetin

Phenacetin contains functional groups such as methyl and amide functional groups. Synthesis of Paracetamol Morning Paracetamol is made by reacting 4-aminophenol with ethanoic anhydride more commonly called acetic anhydride. . Therefore, the disappearance of the acetaminophen spot as well as the increased migration of the reaction spot in the third lane would indicate the completion of the reaction. In order create a fast reaction methyl and primary alkyl halides will be favored.

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Expt4 Synthesis of Phenacetin F19(1) (1).docx

williamson ether synthesis of phenacetin

The reaction is displayed below. What are the limitations of Williamson synthesis? Acetaminophen was first made in the 1870's by the reduction of p -nitrophenol with tin in glacial acetic acid but was not used medicinally until decades later. This clearly shows that because of a lower Rf value, pure acetaminophen, is more polar than our reaction mixture. One is for pure acetaminophen, the middle is for the of the reaction mixture with acetaminophen, and the last one is for the pure reaction mixture. The Mel Temp temperature had a range of 134-1370C and the standard documented melting point for Phenacetin is 133-1360C. Conclusion The Williamson Ether synthesis of Phenacetin was successful in producing the Phenacetin.

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Document 48

williamson ether synthesis of phenacetin

There were subsequent elimination and substitution reactions in the second step. Next, potassium carbonate and a boiling stone are added to the flask. When using alkoxide ions good base they will be in favor of an elimination reaction using a secondary alkyl halide. The IR and NMR spectroscopies were overall successful. Once the phenacetin is dissolved it is then removed from heat and cooled to room temperature and finally placed in an ice bath. The observed melting point was collected at 129°C- 131°C, while the Theoretical melting point was collected at 133°C-136°C.


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Free Essay: Williamson Ether Synthesis of Phenacetin

williamson ether synthesis of phenacetin

Once dissolved, the flask is cooled to room temperature and put on ice to induce recrystallization. Introduction The pharmaceutical industry is one of the largest employers of chemists, involving a large amount of organic synthesis in the development of new drugs. All of these peaks present are indicators that the correct product has formed and further proves our success. Williamson Ether Synthesis 2 Introduction The objective of this lab was to prepare phenacetin through Williamson ether synthesis that utilizes acetaminophen, potassium carbonate, iodoethane, and 2-butanone as the starting components. However, Williamson ether synthesis process requires a strong base such as sodium hydride or sodium metal.

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Williamson Ether Synthesis

williamson ether synthesis of phenacetin

The beaker is covered with a watch glass and solvent travels up the stationary phase. If you remove the strong base, the alcohol is not nucleophilic enough to move onto the next step. This wavenumber should fall within a certain range of a particular functional group which can be used to identify the presence of that functional group. What role does the sodium acetate play in the synthesis of the amide functional group of phenacetin? The acylation of amines with carboxylic acid chlorides leads to the production of one equivalent acid, which will form a salt with unreacted amine and diminish the yield. Enflurane was introduced in the mid-1970s and was eventually replaced by isoflurane. Also, because of the solubility of the solid in the recrystallization solvent, even at low temperatures, any unnecessary prolonged contact with recrystallization solvent, especially if the solvent is not ice-cold will result in loss of product.

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Lab 7 Williamson Ether Synthesis of childhealthpolicy.vumc.org

williamson ether synthesis of phenacetin

What was ether used for? If the solid is dissolved below the boiling point of the solution, too much solvent will be needed, resulting in a poor yield. The second TLC plate had similar values of 0 for pure acetaminophen and 0 of the reaction mixture. An substitution takes place, and this mechanism is depicted in figure 2 below. There were various human errors involved in this lab. The flask is swirled in between additions to mix the organic layer with Na 2 SO 4. Run the TLC again and calculate values.

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Laboratory 10 Williamson Ether Synthesis Preparation of Phenacetin from Acetaminophen (1)

williamson ether synthesis of phenacetin

IR and 1H NMR spectroscopy of acetaminophen. The reflux apparatus is best utilized in order to prevent the solvent or reactant used in the lab to evaporate out or lost. Sodium sulfate is added until there is no new clumping. In this experiment, 1 g of Phenacetin is collected. The drying tube was assembled by adding anhydrous CaCl 2 a drying agent to the device and then plugging both ends with cotton. Because phenacetin has an ether group which is less polar than the alcohol group of the starting acetaminophen, the reaction spot was expected to show a higher Rf value if the reaction was proceeding correctly.

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