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

7. Substitution Reactions

SN1 Reaction

Organic Chemistry

7. Substitution Reactions

SN1 Reaction

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3:44 minutes

Problem 56d

Textbook Question

Often, compounds can be synthesized by more than one method. Show how this 3° alcohol can be made from the following:

(d) a 3° alkyl bromide

Verified step by step guidance

Step 1: Identify the target molecule, which is a tertiary alcohol. The structure provided shows a cyclopentyl group attached to a tertiary carbon that is bonded to an OH group.

Step 2: Recognize that tertiary alcohols can be synthesized via nucleophilic substitution reactions, where a tertiary alkyl halide reacts with a nucleophile such as hydroxide (OH⁻). In this case, the tertiary alkyl bromide will serve as the starting material.

Step 3: Determine the structure of the tertiary alkyl bromide. Replace the OH group in the target molecule with a bromine atom to form the tertiary alkyl bromide. This gives a compound where the bromine is attached to the same tertiary carbon.

Step 4: Plan the reaction. Use a strong nucleophile, such as aqueous NaOH or KOH, to perform an SN1 reaction. The tertiary alkyl bromide undergoes ionization to form a carbocation intermediate, which is then attacked by the hydroxide ion to form the tertiary alcohol.

Step 5: Consider reaction conditions. Since tertiary alkyl halides favor SN1 mechanisms, use polar protic solvents (e.g., water or alcohol) to stabilize the carbocation intermediate and facilitate the substitution reaction.

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Key Concepts

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

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile replaces a leaving group in a molecule. In the case of synthesizing a 3° alcohol from a 3° alkyl bromide, the bromine atom acts as the leaving group, allowing a nucleophile, such as water or an alcohol, to attack the carbon atom, resulting in the formation of the alcohol.

Reactivity of Alkyl Halides

Alkyl halides, such as 3° alkyl bromides, are reactive compounds due to the polar C-X bond, where X is a halogen. The tertiary carbon is more stable and less sterically hindered for nucleophilic attack compared to primary or secondary alkyl halides, making them suitable substrates for nucleophilic substitution reactions that yield alcohols.

Mechanism of SN1 Reactions

The SN1 mechanism involves two steps: the formation of a carbocation intermediate after the leaving group departs, followed by the nucleophile attacking the carbocation. This mechanism is particularly relevant for 3° alkyl halides, as the stability of the carbocation allows for a more favorable reaction pathway, ultimately leading to the formation of the desired 3° alcohol.

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Related Practice

Textbook Question

Propose a mechanism involving a hydride shift or an alkyl shift for each solvolysis reaction. Explain how each rearrangement forms a more stable intermediate.

Hint: Most rearrangements convert 2° (or incipient 1°) carbocations to 3° or resonance-stabilized carbocations.

(c)

Textbook Question

Choose the member of each pair that will react faster by the SN1 mechanism.

c. n-propyl bromide or allyl bromide

d. 1-bromo-2,2-dimethylpropane or 2-bromopropane

Textbook Question

Predict the compound in each pair that will undergo solvolysis (in aqueous ethanol) more rapidly.

(c)

(d)

Textbook Question

Allylic halides have the structure

a. Show how the first-order ionization of an allylic halide leads to a resonance-stabilized cation.

Textbook Question

Give the substitution products expected from solvolysis of each compound by heating in ethanol.

(c)

(d)

Textbook Question

Propose a mechanism for the reaction of benzyl bromide with ethanol to give benzyl ethyl ether.

Textbook Question

Propose a mechanism involving a hydride shift or an alkyl shift for each solvolysis reaction. Explain how each rearrangement forms a more stable intermediate.

Hint: Most rearrangements convert 2° (or incipient 1°) carbocations to 3° or resonance-stabilized carbocations.

(d)

Textbook Question

Predict the products of the following S_N2 reactions.

(c)

(d)

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