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

SN2 Reaction

Organic Chemistry

7. Substitution Reactions

SN2 Reaction

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4:57 minutes

Problem 14c

Textbook Question

Which substitution reaction takes place more rapidly?
c.

Verified step by step guidance

Step 1: Understand the type of substitution reaction involved. Both reactions are nucleophilic substitution reactions, where the nucleophile (CH3O− or CH3S−) attacks the electrophilic carbon in CH3CH2Cl, displacing the leaving group (Cl−).

Step 2: Compare the nucleophiles. CH3O− is an alkoxide ion, while CH3S− is a thiolate ion. Thiolate ions are generally more nucleophilic than alkoxide ions because sulfur is larger and more polarizable than oxygen, making CH3S− a stronger nucleophile.

Step 3: Consider the solvent. The solvent ethanol is protic, meaning it can form hydrogen bonds. Protic solvents tend to stabilize smaller, more basic nucleophiles like CH3O−, reducing their nucleophilicity. Thiolate ions (CH3S−), being less basic and more polarizable, are less affected by protic solvents and retain their high nucleophilicity.

Step 4: Evaluate the leaving group and substrate. CH3CH2Cl is a primary alkyl halide, which is favorable for SN2 reactions. In SN2 reactions, the rate depends on both the nucleophile and the substrate. Since CH3S− is a stronger nucleophile, the reaction with CH3S− will proceed more rapidly.

Step 5: Conclude based on the comparison. The substitution reaction involving CH3CH2Cl + CH3S− in ethanol will take place more rapidly than the reaction involving CH3CH2Cl + CH3O− due to the higher nucleophilicity of CH3S− in a protic solvent.

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Key Concepts

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

Nucleophilicity

Nucleophilicity refers to the ability of a nucleophile to donate an electron pair to an electrophile during a chemical reaction. In this context, CH3O− (methoxide) and CH3S− (thiolate) are both nucleophiles, but their reactivity can differ based on factors such as charge, electronegativity, and solvent effects. Generally, stronger nucleophiles react more rapidly in substitution reactions.

Substitution Reactions

Substitution reactions involve the replacement of one functional group in a molecule with another. In organic chemistry, these reactions can be classified as either nucleophilic substitution (S_N1 or S_N2 mechanisms) depending on the structure of the substrate and the nature of the nucleophile. The rate of these reactions is influenced by the strength of the nucleophile and the leaving group.

Solvent Effects

The choice of solvent can significantly impact the rate of substitution reactions. Polar protic solvents, like ethanol, can stabilize ions and influence the nucleophilicity of the reactants. For example, in a polar protic solvent, nucleophiles may be less reactive due to solvation effects, which can affect the overall reaction rate and mechanism.

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Textbook Question

How will the rate of each of the following S_N2 reactions change if it is carried out in a more polar solvent?

Textbook Question

2-Acetoxycyclohexyl tosylate reacts with acetate ion to form 1,2-cyclohexanediol diacetate. The reaction is stereospecific—that is, the stereoisomers obtained as products depend on the stereoisomer used as a reactant. Recall that because 2-acetoxycyclohexyl tosylate has two asymmetric centers, it has four stereoisomers—two are cis and two are trans. Explain the following observations:

a. Both cis reactants form an optically active trans product, but each cis reactant forms a different trans product.

Textbook Question

c. A trans reactant is more reactive than a cis reactant.

Textbook Question

Which substitution reaction takes place more rapidly?

Textbook Question

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

Textbook Question

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

Textbook Question

Starting with an alkyl halide, how could the following compounds be prepared?

a. 2-methoxybutane