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

8. Elimination Reactions

Cumulative Substitution/Elimination

Organic Chemistry

8. Elimination Reactions

Cumulative Substitution/Elimination

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Problem 68

Textbook Question

Why is the S_N1 reaction shown an inefficient way of synthesizing ethers?

Verified step by step guidance

The SN1 reaction mechanism involves the formation of a carbocation intermediate. In the given reaction, the leaving group is chloride (Cl-) from the cyclohexyl chloride, which forms a cyclohexyl carbocation.

Carbocations are prone to rearrangements, especially if a more stable carbocation can be formed. In this case, the cyclohexyl carbocation is relatively stable, but rearrangements can still occur, leading to side products.

The nucleophile in this reaction is isopropanol (CH3CHOHCH3). In SN1 reactions, the nucleophile attacks the carbocation, forming the ether product. However, the reaction can be inefficient due to competing reactions such as elimination, which can occur under similar conditions.

The SN1 mechanism is generally not preferred for synthesizing ethers because it often leads to a mixture of products due to the possibility of rearrangements and side reactions. This reduces the yield and purity of the desired ether product.

Alternative methods, such as the Williamson ether synthesis, are typically more efficient for synthesizing ethers. This method involves an SN2 reaction, which avoids carbocation intermediates and provides better control over the reaction outcome.

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Key Concepts

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

S_N 1 Reaction Mechanism

The S_N 1 reaction is a nucleophilic substitution mechanism that involves two main steps: the formation of a carbocation intermediate and the subsequent attack of a nucleophile. This reaction is characterized by its unimolecular rate-determining step, meaning the rate depends only on the concentration of the substrate. The stability of the carbocation is crucial, as more stable carbocations lead to faster reactions.

Carbocation Stability

Carbocation stability is a key factor in S_N 1 reactions, as more stable carbocations are formed from tertiary or resonance-stabilized substrates. The efficiency of the S_N 1 reaction in synthesizing ethers is limited because the formation of a stable carbocation can be slow, and if the carbocation is not sufficiently stable, it may lead to rearrangements or side reactions, reducing the yield of the desired ether.

Ethers and Their Synthesis

Ethers are organic compounds characterized by an oxygen atom bonded to two alkyl or aryl groups. The synthesis of ethers typically requires more efficient methods, such as the Williamson ether synthesis, which involves the reaction of an alkoxide ion with a primary alkyl halide. The S_N 1 mechanism is inefficient for ether synthesis because it can lead to a mixture of products, including alcohols and alkenes, rather than a clean ether product.

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Related Practice

Textbook Question

Show how you would prepare cyclopentene from each compound.

a. cyclopentanol

b. cyclopentyl bromide

Textbook Question

Show how this 1° alcohol can be made from the following:

(a) a 1° alkyl bromide

Textbook Question

S_N1 substitution and E1 elimination frequently compete in the same reaction.

a. Propose a mechanism and predict the products for the solvolysis of 2-bromo-2,3,3-trimethylbutane in methanol.

Textbook Question

Suggest a bromoalkane and the conditions necessary to produce the alkenes shown.

(a)

Textbook Question

Of the three possible elimination mechanisms (Figure 12.50), this chapter focused on two of them (E1 and E2). The third possibility occurs in situations like the one below. What makes this mechanism favored under these conditions?

Multiple Choice

Predict the mechanism for the following reactions. Provide the full mechanism and draw the final product.

Multiple Choice

Predict the mechanism for the following reactions. Provide the full mechanism and draw the final product.

Multiple Choice

Predict the mechanism for the following reactions. Provide the full mechanism and draw the final product.

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