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

Substitution Comparison

Organic Chemistry

7. Substitution Reactions

Substitution Comparison

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1:03 minutes

Problem 30b

Textbook Question

Suggest a mechanism for the following substitution reactions.
(b)

Verified step by step guidance

Identify the type of substitution reaction: Determine whether the reaction is likely to proceed via an SN1 or SN2 mechanism. This depends on factors such as the structure of the substrate (primary, secondary, or tertiary carbon), the strength of the nucleophile, and the solvent used.

Analyze the substrate: If the carbon attached to the leaving group is tertiary or secondary, the reaction may proceed via an SN1 mechanism. If it is primary or methyl, it is more likely to proceed via an SN2 mechanism.

Examine the nucleophile and solvent: A strong nucleophile in a polar aprotic solvent favors an SN2 mechanism, while a weak nucleophile in a polar protic solvent favors an SN1 mechanism.

Propose the mechanism: For an SN1 reaction, the first step involves the departure of the leaving group to form a carbocation intermediate. The nucleophile then attacks the carbocation to form the product. For an SN2 reaction, the nucleophile attacks the substrate in a single concerted step, displacing the leaving group.

Draw the mechanism: Use curved arrows to show the movement of electrons. For SN1, show the formation of the carbocation intermediate and the subsequent attack by the nucleophile. For SN2, show the backside attack of the nucleophile and the simultaneous departure of the leaving group.

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Key Concepts

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

Nucleophilic Substitution Mechanisms

Nucleophilic substitution reactions involve the replacement of a leaving group in a molecule by a nucleophile. The two primary mechanisms are SN1 and SN2. SN1 is a two-step process where the leaving group departs first, forming a carbocation intermediate, followed by nucleophilic attack. In contrast, SN2 is a one-step process where the nucleophile attacks the substrate simultaneously as the leaving group departs, leading to a concerted reaction.

Leaving Groups

A leaving group is an atom or group that can depart from the parent molecule during a substitution reaction. Good leaving groups are typically stable after departure, such as halides (Cl, Br, I) or sulfonate groups (like tosylate). The ability of a leaving group to stabilize its negative charge or form a stable molecule is crucial for the reaction's feasibility and rate.

Nucleophiles

Nucleophiles are species that donate an electron pair to form a new bond during a substitution reaction. They can be negatively charged ions (like OH⁻ or CN⁻) or neutral molecules with lone pairs (like water or ammonia). The strength and reactivity of a nucleophile depend on its charge, electronegativity, and steric hindrance, influencing the mechanism and outcome of the substitution reaction.

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