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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6:06 minutes

Problem 14f

Textbook Question

Predict the major products of the following substitutions.
f.

Verified step by step guidance

Identify the type of substitution reaction: The presence of KF (potassium fluoride) and 18-crown-6 suggests that this is a nucleophilic substitution reaction. The 18-crown-6 ether acts as a phase-transfer catalyst, solubilizing the potassium ion and leaving fluoride (F⁻) as a free nucleophile in the organic solvent (CH₃CN).

Analyze the substrate: 1-chloropentane is a primary alkyl halide. Primary alkyl halides typically undergo SN2 (bimolecular nucleophilic substitution) reactions because the steric hindrance around the carbon attached to the leaving group is minimal.

Determine the nucleophile and leaving group: The nucleophile is fluoride (F⁻), and the leaving group is chloride (Cl⁻). In an SN2 reaction, the nucleophile attacks the carbon attached to the leaving group from the opposite side, leading to an inversion of configuration at the carbon center.

Write the reaction mechanism: The fluoride ion (F⁻) attacks the carbon bonded to the chlorine atom in a single concerted step, displacing the chloride ion (Cl⁻) and forming a new C-F bond. This results in the substitution of the chlorine atom with a fluorine atom.

Predict the major product: The major product of this reaction will be 1-fluoropentane, as the fluoride ion replaces the chlorine atom in the primary alkyl halide through 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 with a nucleophile. In this context, 1-chloropentane serves as the substrate, where the chlorine atom is the leaving group. Understanding the mechanism (either SN1 or SN2) is crucial for predicting the products, as it influences the reaction pathway and the stereochemistry of the resulting compounds.

Crown Ethers

Crown ethers, such as 18-crown-6, are cyclic compounds that can selectively bind cations, enhancing the solubility of ionic species in nonpolar solvents. In this reaction, 18-crown-6 facilitates the nucleophilicity of the fluoride ion (from KF) by stabilizing it in the solvent (CH3CN), which can lead to a more favorable substitution reaction with 1-chloropentane.

Solvent Effects on Reaction Mechanisms

The choice of solvent can significantly influence the mechanism and outcome of nucleophilic substitution reactions. In this case, CH3CN (acetonitrile) is a polar aprotic solvent that enhances the nucleophilicity of fluoride ions, promoting an SN2 mechanism. Understanding how solvents affect reaction rates and mechanisms is essential for predicting the major products of the reaction.

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What nucleophiles would form the following compounds as a result of reacting with 1-iodobutane?

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What nucleophiles would form the following compounds as a result of reacting with 1-iodobutane?

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Aldolase shows no activity if it is incubated with iodoacetic acid before fructose-1,6-bisphosphate is added to the reaction mixture. What causes this loss of activity?

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Predict the major products of the following substitutions.

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Chlorocyclohexane reacts with sodium cyanide (NaCN) in ethanol to give cyanocyclohexane. The rate of formation of cyanocyclohexane increases when a small amount of sodium iodide is added to the solution. Explain this acceleration in the rate.

Textbook Question

Draw perspective structures or Fischer projections for the substitution products of the following reactions.

(b)

Textbook Question

a. Optically active 2-bromobutane undergoes racemization on treatment with a solution of KBr. Give a mechanism for this racemization.

b. In contrast, optically active butan-2-ol does not racemize on treatment with a solution of KOH. Explain why a reaction like that in part (a) does not occur.

Textbook Question

For each reaction, give the expected substitution product, and predict whether the mechanism will be predominantly first order (SN1) or second order (SN2).

c. 1-iodo-1-methylcyclohexane + ethanol

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Predict the major products of the following substitutions.f.

Key Concepts

Nucleophilic Substitution Reactions

Crown Ethers

Solvent Effects on Reaction Mechanisms

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Predict the major products of the following substitutions.
f.