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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3:54 minutes

Problem 30a

Textbook Question

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

Verified step by step guidance

Step 1: Identify the type of substitution reaction. Determine whether the reaction follows an SN1 (unimolecular nucleophilic substitution) or SN2 (bimolecular nucleophilic substitution) mechanism based on the substrate, nucleophile, and solvent conditions.

Step 2: Analyze the substrate structure. If the substrate is tertiary or stabilized by resonance, it likely undergoes an SN1 mechanism. If the substrate is primary or secondary and sterically accessible, it likely undergoes an SN2 mechanism.

Step 3: Consider the nucleophile. A strong nucleophile typically favors an SN2 mechanism, while a weak nucleophile often supports an SN1 mechanism. Evaluate the nucleophile's charge, electronegativity, and steric hindrance.

Step 4: Examine the solvent. Polar protic solvents (e.g., water, alcohols) stabilize carbocations and favor SN1 reactions, while polar aprotic solvents (e.g., acetone, DMSO) enhance nucleophilic attack and favor SN2 reactions.

Step 5: Write the detailed mechanism. For SN1, show the formation of the carbocation intermediate followed by nucleophilic attack. For SN2, depict the concerted one-step process where the nucleophile attacks the substrate and the leaving group departs simultaneously.

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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, while SN2 is a one-step process where the nucleophile attacks the substrate simultaneously as the leaving group departs.

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 weak bases, as they can stabilize the negative charge after leaving. Common examples include halides (like Cl⁻, Br⁻) and sulfonate groups (like TsO⁻). The ability of a leaving group to depart influences the reaction mechanism and rate.

Nucleophiles

Nucleophiles are species that donate an electron pair to form a chemical bond in a reaction. They are typically negatively charged or neutral molecules with lone pairs of electrons. The strength and reactivity of a nucleophile can significantly affect the rate and outcome of substitution reactions, with stronger nucleophiles favoring SN2 mechanisms and weaker ones often participating in SN1 reactions.

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