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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Problem 28g

Textbook Question

For each solvent, indicate the most likely substitution reaction to take place.
(g)

Verified step by step guidance

Analyze the structure provided: The molecule shown is isopropanol (2-propanol), which contains a secondary alcohol group (-OH) attached to a secondary carbon.

Understand the substitution reaction types: Substitution reactions can occur via two main mechanisms: SN1 (unimolecular nucleophilic substitution) and SN2 (bimolecular nucleophilic substitution). The choice of mechanism depends on factors such as the solvent, the structure of the substrate, and the nucleophile.

Consider the solvent's role: Polar protic solvents (e.g., water, alcohols) favor the SN1 mechanism because they stabilize the carbocation intermediate formed during the reaction. Polar aprotic solvents (e.g., acetone, DMSO) favor the SN2 mechanism because they do not stabilize carbocations but enhance the nucleophile's reactivity.

Evaluate the substrate: Isopropanol has a secondary carbon, which can form a relatively stable carbocation. This makes it more likely to undergo an SN1 reaction in polar protic solvents. However, in polar aprotic solvents, the reaction may proceed via the SN2 mechanism due to the increased nucleophilic attack.

Determine the most likely substitution reaction: If the solvent is polar protic (e.g., water or alcohol), the reaction is likely to proceed via the SN1 mechanism. If the solvent is polar aprotic (e.g., acetone or DMSO), the reaction is likely to proceed via the SN2 mechanism.

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Key Concepts

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

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions involve the replacement of a leaving group in a molecule by a nucleophile. These reactions can occur via two main mechanisms: SN1, which is unimolecular and involves a carbocation intermediate, and SN2, which is bimolecular and involves a direct attack by the nucleophile. The choice of mechanism often depends on the structure of the substrate and the nature of the solvent.

Solvent Effects on Reaction Mechanisms

The choice of solvent can significantly influence the rate and mechanism of nucleophilic substitution reactions. Polar protic solvents stabilize carbocations and can favor SN1 reactions, while polar aprotic solvents enhance the nucleophilicity of the nucleophile, promoting SN2 reactions. Understanding the solvent's properties is crucial for predicting the outcome of substitution reactions.

Leaving Groups

Leaving groups are atoms or groups that can depart from the parent molecule during a substitution reaction. Good leaving groups, such as halides or sulfonate esters, stabilize the negative charge after leaving, facilitating the reaction. The ability of a leaving group to depart is a key factor in determining the feasibility and mechanism of the substitution reaction.

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