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In a paragraph Outline a mechanism for the formation of the ether

In a paragraph Outline a mechanism for the formation of the ether

Chemistry
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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In a paragraph 

Outline a mechanism for the formation of the ether 

Discuss key techniques used in the synthesis briefly

**Introduction** Ethers can be produced from two alcohols. However, unless you want to have symmetrical ethers (i.e., diethyl ether derived from ethanol), ether synthesis from different alcohols in the same reaction mixture will produce a variety of products. To produce an unsymmetrical ether (i.e., tert-butyl methyl ether, MTBE), one component must be an alkyl halide, and the other component is an alkoxide (or phenoxide) ion. The alkoxide ion can be any alkoxide but the alkyl halide is usually going to be a primary or methyl halide since the reaction usually follows an Sₙ2 mechanism. The reason for this is that a primary halide would have less chance of undergoing elimination, hence you can end with the product you want. In this experiment, p-cresol and chloroacetic acid will be used. The phenol can easily be converted into the phenoxide ion. This procedure is typical for reactions used to produce asymmetrical ethers. The Williamson ether synthesis is one of several organic chemistry reactions referred to as “Named Reactions”, which employ the name of the scientist who developed it. Many of the reactions used in organic chemistry are described as being named reactions. The Fischer Esterification reaction was a “named reaction”, referring to Emil Fischer who discovered and popularized it as a method to produce esters. Likewise, the Grignard Reaction was similarly named after its discoverer. In today's experiment, the Williamson ether synthesis is another named reaction, developed by Dr. Alexander W. Williamson who was a professor at University College in London in the latter part of the 1800's. This reaction has been around for a long time and has been used successfully to synthesize many different ethers. For this reaction to occur at a high yield, the alcohol portion can be either 1°, 2°, or 3°, which can then be converted into an alkoxide nucleophile using basic conditions (i.e., NaOH can be used as the base). The alkoxide ion then reacts via an Sₙ2 mechanism with a primary alkyl halide (in the current experiment chloroacetic acid will be used which also cannot undergo elimination). For example, if the alkyl halide was either 2° or 3°, an E2 elimination reaction would likely take place instead of substitution. The simplest way to synthesize an ether is to have an alkoxide react with a primary haloalk
Transcribed Image Text:**Introduction** Ethers can be produced from two alcohols. However, unless you want to have symmetrical ethers (i.e., diethyl ether derived from ethanol), ether synthesis from different alcohols in the same reaction mixture will produce a variety of products. To produce an unsymmetrical ether (i.e., tert-butyl methyl ether, MTBE), one component must be an alkyl halide, and the other component is an alkoxide (or phenoxide) ion. The alkoxide ion can be any alkoxide but the alkyl halide is usually going to be a primary or methyl halide since the reaction usually follows an Sₙ2 mechanism. The reason for this is that a primary halide would have less chance of undergoing elimination, hence you can end with the product you want. In this experiment, p-cresol and chloroacetic acid will be used. The phenol can easily be converted into the phenoxide ion. This procedure is typical for reactions used to produce asymmetrical ethers. The Williamson ether synthesis is one of several organic chemistry reactions referred to as “Named Reactions”, which employ the name of the scientist who developed it. Many of the reactions used in organic chemistry are described as being named reactions. The Fischer Esterification reaction was a “named reaction”, referring to Emil Fischer who discovered and popularized it as a method to produce esters. Likewise, the Grignard Reaction was similarly named after its discoverer. In today's experiment, the Williamson ether synthesis is another named reaction, developed by Dr. Alexander W. Williamson who was a professor at University College in London in the latter part of the 1800's. This reaction has been around for a long time and has been used successfully to synthesize many different ethers. For this reaction to occur at a high yield, the alcohol portion can be either 1°, 2°, or 3°, which can then be converted into an alkoxide nucleophile using basic conditions (i.e., NaOH can be used as the base). The alkoxide ion then reacts via an Sₙ2 mechanism with a primary alkyl halide (in the current experiment chloroacetic acid will be used which also cannot undergo elimination). For example, if the alkyl halide was either 2° or 3°, an E2 elimination reaction would likely take place instead of substitution. The simplest way to synthesize an ether is to have an alkoxide react with a primary haloalk
**Title: Williamson Ether Synthesis: Reaction of *p*-Cresol with α-Chloroacetic Acid** **Introduction** We will carry out the reaction shown above to illustrate the Williamson ether synthesis and to identify (if different isomeric cresols were used) by the melting point of the product. The reaction has a 75% yield. **Procedure** 1. **Preparation** - Dissolve 4.0 g of KOH pellets (note: NaOH cannot be used) in 8 mL of water within a 250-mL round-bottom flask. - Use a flask with two ground-glass openings, one for the condenser unit and the other for the separatory funnel. 2. **Mixing Reactants** - Add 2.0 grams of *p*-cresol to the flask in the hood. - Swirl until the solution is homogeneous. - Add three boiling stones, and fit the flask with a reflux condenser. Heat to a gentle boil. 3. **Addition of Chloroacetic Acid** - Once boiling, add 6 mL of a 50% aqueous chloroacetic acid solution dropwise using a separatory funnel. - Continue refluxing for another 10 minutes after the addition. 4. **Post-reaction Processing** - Transfer the solution to a small beaker while hot to prevent solid formation inside the flask. - Add about 10 mL of water, pour into a 100-mL beaker. Cool to room temperature. - Acidify with concentrated 12 M HCl until the pH is acidic (pH=2). 5. **Isolation of Product** - Ensure potassium salt does not isolate. Use ice baths to solidify the product. - After 15 min on ice, filter and collect using a Büchner funnel setup. - Recrystallize by adding the entire crude product to boiling water. Use less than 50 mL of water. 6. **Final Steps** - Collect and dry the re-crystallized product using vacuum filtration. - Weigh, measure the melting point, and prepare the product for NMR spectrum analysis. **Figure Description** - The diagram illustrates the reaction between *p*-cresol and α-chloroacetic acid, showing reagents and conditions. - The first step involves *p*-cresol and KOH
Transcribed Image Text:**Title: Williamson Ether Synthesis: Reaction of *p*-Cresol with α-Chloroacetic Acid** **Introduction** We will carry out the reaction shown above to illustrate the Williamson ether synthesis and to identify (if different isomeric cresols were used) by the melting point of the product. The reaction has a 75% yield. **Procedure** 1. **Preparation** - Dissolve 4.0 g of KOH pellets (note: NaOH cannot be used) in 8 mL of water within a 250-mL round-bottom flask. - Use a flask with two ground-glass openings, one for the condenser unit and the other for the separatory funnel. 2. **Mixing Reactants** - Add 2.0 grams of *p*-cresol to the flask in the hood. - Swirl until the solution is homogeneous. - Add three boiling stones, and fit the flask with a reflux condenser. Heat to a gentle boil. 3. **Addition of Chloroacetic Acid** - Once boiling, add 6 mL of a 50% aqueous chloroacetic acid solution dropwise using a separatory funnel. - Continue refluxing for another 10 minutes after the addition. 4. **Post-reaction Processing** - Transfer the solution to a small beaker while hot to prevent solid formation inside the flask. - Add about 10 mL of water, pour into a 100-mL beaker. Cool to room temperature. - Acidify with concentrated 12 M HCl until the pH is acidic (pH=2). 5. **Isolation of Product** - Ensure potassium salt does not isolate. Use ice baths to solidify the product. - After 15 min on ice, filter and collect using a Büchner funnel setup. - Recrystallize by adding the entire crude product to boiling water. Use less than 50 mL of water. 6. **Final Steps** - Collect and dry the re-crystallized product using vacuum filtration. - Weigh, measure the melting point, and prepare the product for NMR spectrum analysis. **Figure Description** - The diagram illustrates the reaction between *p*-cresol and α-chloroacetic acid, showing reagents and conditions. - The first step involves *p*-cresol and KOH
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