Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

12. Alcohols, Ethers, Epoxides and Thiols

Williamson Ether Synthesis

Organic Chemistry

12. Alcohols, Ethers, Epoxides and Thiols

Williamson Ether Synthesis

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Problem 67a

Textbook Question

Two different Williamson ether syntheses can be used to make the compound in (a). Show them. The compound in (b), however, can only be made one way. Show it and explain why a second Williamson ether synthesis is not possible.
(a)

Verified step by step guidance

Step 1: Understand the Williamson ether synthesis, which involves the reaction of an alkoxide ion with a primary alkyl halide to form an ether. The alkoxide ion is typically generated from an alcohol by deprotonation.

Step 2: Analyze the compound in image (a). It is an ether with two distinct alkyl groups attached to the oxygen atom: a cyclopentyl group and a 2-(N-methylpyrrole)ethyl group.

Step 3: Identify the two possible Williamson ether synthesis routes for the compound in (a). Route 1: Use cyclopentanol to form the cyclopentoxide ion, and react it with 2-(N-methylpyrrole)ethyl bromide. Route 2: Use 2-(N-methylpyrrole)ethanol to form the 2-(N-methylpyrrole)ethoxide ion, and react it with cyclopentyl bromide.

Step 4: Consider the compound in (b) (not shown here). Williamson ether synthesis requires a primary alkyl halide. If the compound in (b) has a secondary or tertiary alkyl halide, it may not be suitable for the synthesis due to steric hindrance or elimination reactions.

Step 5: Explain why a second Williamson ether synthesis is not possible for compound (b). If the alkyl halide is secondary or tertiary, the reaction may favor elimination over substitution, making the synthesis of the ether difficult or impossible.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Williamson Ether Synthesis

Williamson ether synthesis is a method for producing ethers through the reaction of an alkoxide ion with a primary alkyl halide. This reaction typically involves an SN2 mechanism, where the nucleophile attacks the electrophile, leading to the formation of the ether. Understanding this process is crucial for determining the different pathways to synthesize a given ether compound.

SN2 Mechanism

The SN2 mechanism is a type of nucleophilic substitution reaction characterized by a single concerted step where the nucleophile attacks the electrophile, displacing a leaving group. This mechanism is favored by primary substrates due to less steric hindrance, making it essential to recognize when analyzing the feasibility of different synthetic routes in ether formation.

Steric Hindrance

Steric hindrance refers to the prevention of reactions due to the spatial arrangement of atoms within a molecule. In the context of Williamson ether synthesis, secondary and tertiary alkyl halides are less reactive in SN2 reactions because their bulky groups hinder the approach of the nucleophile. This concept is vital for understanding why certain ethers can only be synthesized through specific pathways.

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Related Practice

Textbook Question

Predict the product of the following reactions. [Two of them are Williamson ether syntheses. Why isn't the other?].

(a)

Textbook Question

Identify the alkene and alcohol partners that could be used to make the following ethers.

(a)

Textbook Question

Predict the product of the following reactions. [Two of them are Williamson ether syntheses. Why isn't the other?].

(c)

Textbook Question

Suggest a phenoxide and an alkyl halide to make the following aryl alkyl ethers.

(b)

Textbook Question

In contrast to Assessment 13.102, only one combination of haloalkane and alkoxide can be used in the Williamson ether synthesis to make the ether shown. Identify the combination and explain why it is the only combination that works.

Textbook Question

Predict the product of the following reactions. [Two of them are Williamson ether syntheses. Why isn't the other?].

(b)

Textbook Question

In Chapter 12, we learned that crown ethers were used to increase the rate of S_N2 reactions (Assessment 12.80). Suggest a synthesis of 15-crown-5 using the reactions learned here in Chapter 13.

Textbook Question

Suggest a phenoxide and an alkyl halide to make the following aryl alkyl ethers.

(a)

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