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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4:45 minutes

Problem 112

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.

Verified step by step guidance

Identify the structure of 15-crown-5, which consists of a cyclic ether with five ethylene oxide units. This means it has five oxygen atoms and a total of 15 atoms in the ring.

To synthesize 15-crown-5, start with ethylene glycol as the base unit. Ethylene glycol can be converted into ethylene oxide, which is a key building block for crown ethers.

Use a Williamson ether synthesis to link the ethylene oxide units. This involves deprotonating the hydroxyl group of ethylene glycol to form an alkoxide ion, which can then attack an ethylene oxide molecule to form an ether linkage.

Repeat the ether formation process to build the chain of ethylene oxide units. This step is crucial to form the linear precursor that will eventually be cyclized into the crown ether.

Finally, cyclize the linear polyether chain to form the cyclic structure of 15-crown-5. This can be achieved by using a suitable base to deprotonate the terminal hydroxyl group, allowing it to attack the other end of the chain and close the ring.

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Key Concepts

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

Crown Ethers

Crown ethers are cyclic compounds that contain multiple ether groups, which can selectively bind cations due to their unique size and shape. The number in their name indicates the number of atoms in the ring, and their ability to form complexes with metal ions enhances solubility and reactivity in organic reactions, particularly in S_N2 mechanisms.

S_N2 Reactions

S_N2 (substitution nucleophilic bimolecular) reactions involve a nucleophile attacking an electrophile, resulting in the simultaneous displacement of a leaving group. This mechanism is characterized by a single concerted step, where the reaction rate depends on the concentration of both the nucleophile and the substrate, making it sensitive to steric hindrance.

Synthetic Pathways

Synthetic pathways refer to the series of chemical reactions and transformations used to construct a target molecule from simpler precursors. Understanding the functional groups, reaction conditions, and mechanisms involved is crucial for designing efficient syntheses, such as that of 15-crown-5, which may involve alkylation and etherification reactions.

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Related Practice

Textbook Question

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

(b)

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)

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

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

(a)

Textbook Question

Provide the reagents necessary to carry out the following synthesis. What is the purpose of steps (a) and (e)?

Textbook Question

How could you synthesize isopropyl propyl ether, using isopropyl alcohol as the only carbon-containing reagent?

Textbook Question

Draw the product of each of the following reactions:

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In Chapter 12, we learned that crown ethers were used to increase the rate of SN2 reactions (Assessment 12.80). Suggest a synthesis of 15-crown-5 using the reactions learned here in Chapter 13.

Key Concepts

Crown Ethers

S_N2 Reactions

Synthetic Pathways

Watch next

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.