the background for the experiment (=mechanism)

Chemistry
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ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
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 the background for the experiment (=mechanism) 

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**Title: Williamson Ether Synthesis of p-cresol with α-chloroacetic acid**

**Introduction:**
This experiment demonstrates the Williamson ether synthesis using p-cresol and α-chloroacetic acid. The goal is to synthesize an ether and determine its purity and identity through melting point analysis. The expected reaction yield is 75%.

**Procedure:**

1. **Preparation of Reaction Mixture:**
   - Dissolve 4.0 g of KOH pellets in 8 mL of water in a 250-mL round-bottom flask with two ground-glass openings.
   - Add 2.0 grams of p-cresol to the flask. Swirl until homogeneous.
   - Add three boiling stones and attach a reflux condenser.

2. **Reaction Process:**
   - Heat the mixture to a gentle boil.
   - Add 6 mL of 50% aqueous chloroacetic acid dropwise using a separatory funnel.
   - Continue refluxing for 10 minutes after the addition of chloroacetic acid.

3. **Post-Reaction Operations:**
   - Transfer the mixture to a small beaker while warm.
   - Dilute by adding about 10 mL of water, then transfer to a 100-mL beaker.
   - Acidify to pH 2 using concentrated 12 M HCl, monitoring with pH paper.

4. **Purification:**
   - Cool the mixture in an ice bath to precipitate the product.
   - Filter the solid using a Büchner funnel and vacuum filtration.
   - Re-crystallize by dissolving the crude product in 50 mL of water and cooling.

5. **Final Steps:**
   - Collect and vacuum-filter the re-crystallized product.
   - Dry the product before weighing.

**Analysis:**
   - Weigh the dried product to calculate yield.
   - Determine the melting point for product identification.
   - Acquire the ^1H and ^13C-NMR spectra in DMSO-d₆.

**Figure:**
- Depicts the chemical reaction of p-cresol with α-chloroacetic acid, highlighting the transformation through the Williamson ether synthesis. Reactants and products are chemically structured with appropriate reagents indicated for each step.
Transcribed Image Text:**Title: Williamson Ether Synthesis of p-cresol with α-chloroacetic acid** **Introduction:** This experiment demonstrates the Williamson ether synthesis using p-cresol and α-chloroacetic acid. The goal is to synthesize an ether and determine its purity and identity through melting point analysis. The expected reaction yield is 75%. **Procedure:** 1. **Preparation of Reaction Mixture:** - Dissolve 4.0 g of KOH pellets in 8 mL of water in a 250-mL round-bottom flask with two ground-glass openings. - Add 2.0 grams of p-cresol to the flask. Swirl until homogeneous. - Add three boiling stones and attach a reflux condenser. 2. **Reaction Process:** - Heat the mixture to a gentle boil. - Add 6 mL of 50% aqueous chloroacetic acid dropwise using a separatory funnel. - Continue refluxing for 10 minutes after the addition of chloroacetic acid. 3. **Post-Reaction Operations:** - Transfer the mixture to a small beaker while warm. - Dilute by adding about 10 mL of water, then transfer to a 100-mL beaker. - Acidify to pH 2 using concentrated 12 M HCl, monitoring with pH paper. 4. **Purification:** - Cool the mixture in an ice bath to precipitate the product. - Filter the solid using a Büchner funnel and vacuum filtration. - Re-crystallize by dissolving the crude product in 50 mL of water and cooling. 5. **Final Steps:** - Collect and vacuum-filter the re-crystallized product. - Dry the product before weighing. **Analysis:** - Weigh the dried product to calculate yield. - Determine the melting point for product identification. - Acquire the ^1H and ^13C-NMR spectra in DMSO-d₆. **Figure:** - Depicts the chemical reaction of p-cresol with α-chloroacetic acid, highlighting the transformation through the Williamson ether synthesis. Reactants and products are chemically structured with appropriate reagents indicated for each step.
**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 haloalkane or a sul
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 haloalkane or a sul
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