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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1:17 minutes

Problem 12b

Textbook Question

Practice your electron-pushing skills by drawing a mechanism for the following S_N1 reactions.
(b)

Verified step by step guidance

Step 1: Understand the Sₙ1 reaction mechanism. Sₙ1 stands for 'substitution nucleophilic unimolecular,' which involves two steps: (1) the formation of a carbocation intermediate and (2) the nucleophilic attack on the carbocation.

Step 2: Identify the leaving group in the substrate molecule. The leaving group is typically a halide or another group that can stabilize the negative charge after leaving. Draw the substrate and show the bond breaking between the carbon and the leaving group.

Step 3: Illustrate the formation of the carbocation intermediate. After the leaving group departs, the carbon atom bonded to it becomes positively charged. Ensure you consider the stability of the carbocation (e.g., tertiary carbocations are more stable than secondary or primary).

Step 4: Show the nucleophilic attack. The nucleophile (e.g., water, hydroxide ion, or another electron-rich species) will attack the carbocation, forming a new bond. Use curved arrows to represent the movement of electrons during this step.

Step 5: If applicable, include any proton transfer or rearrangement steps to finalize the product. For example, if the nucleophile is water, a proton may need to be removed to yield the final neutral product. Ensure all charges are balanced and the product is correctly drawn.

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Key Concepts

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

Sₙ1 Mechanism

The Sₙ1 (substitution nucleophilic unimolecular) mechanism involves a two-step process where the rate-determining step is the formation of a carbocation intermediate. In this mechanism, the leaving group departs first, creating a positively charged carbocation, which is then attacked by a nucleophile. This mechanism is favored in tertiary substrates due to their ability to stabilize the carbocation.

Carbocation Stability

Carbocation stability is crucial in Sₙ1 reactions, as more stable carbocations form more readily. Stability increases with the degree of substitution: tertiary > secondary > primary. Factors such as resonance and inductive effects also play a role in stabilizing carbocations, influencing the reaction pathway and rate.

Nucleophiles

Nucleophiles are species that donate an electron pair to form a chemical bond in a reaction. In Sₙ1 reactions, the nucleophile attacks the carbocation after its formation. The strength and nature of the nucleophile can significantly affect the reaction rate and product distribution, with stronger nucleophiles generally leading to faster reactions.

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