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

8. Elimination Reactions

SN1 SN2 E1 E2 Chart (Big Daddy Flowchart)

Organic Chemistry

8. Elimination Reactions

SN1 SN2 E1 E2 Chart (Big Daddy Flowchart)

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Problem 90c

Textbook Question

Identify whether each of the following reactions proceed by an S_N1, S_N2, E1, or E2 mechanism.
(c)

Verified step by step guidance

Analyze the substrate: The substrate is a benzylic sulfonate ester, which is a good leaving group. The benzylic position is stabilized by resonance, making it favorable for substitution reactions.

Examine the nucleophile: KCN (potassium cyanide) is a strong nucleophile. Strong nucleophiles typically favor SN2 mechanisms over SN1 mechanisms.

Consider the solvent: DMSO (dimethyl sulfoxide) is a polar aprotic solvent. Polar aprotic solvents stabilize the transition state of SN2 reactions and do not stabilize carbocations, making SN2 more likely than SN1.

Evaluate steric hindrance: The benzylic position is relatively unhindered, which is ideal for an SN2 reaction since SN2 requires a backside attack by the nucleophile.

Rule out elimination mechanisms: There is no strong base present, and the reaction conditions (strong nucleophile and polar aprotic solvent) are more suited for substitution rather than elimination. Therefore, E1 and E2 mechanisms are unlikely.

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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 can occur via two primary mechanisms: S_N1 and S_N2. S_N1 reactions involve a two-step process where the leaving group departs first, forming a carbocation intermediate, followed by nucleophilic attack. In contrast, S_N2 reactions are single-step processes where the nucleophile attacks the substrate simultaneously as the leaving group departs, leading to a concerted mechanism.

Elimination Reactions

Elimination reactions can also occur through two mechanisms: E1 and E2. E1 reactions involve the formation of a carbocation intermediate after the leaving group departs, followed by deprotonation to form a double bond. E2 reactions are concerted, where the base abstracts a proton while the leaving group departs, resulting in the formation of a double bond in a single step.

Factors Influencing Mechanism Choice

The choice between S_N1, S_N2, E1, and E2 mechanisms depends on several factors, including the structure of the substrate (primary, secondary, or tertiary), the strength and concentration of the nucleophile or base, and the solvent used. Polar protic solvents favor S_N1 and E1 mechanisms by stabilizing carbocations, while polar aprotic solvents favor S_N2 and E2 mechanisms by enhancing nucleophilicity.

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Related Practice

Textbook Question

Predict the product of the following reactions.

(e)

Textbook Question

For which of the following reactions would you expect elimination to be more favored than substitution?

(e)

Textbook Question

For each pair, choose the haloalkane that would react most quickly in an S_N1 or E1 reaction.

(a)

Textbook Question

Predict the product(s) that would result when the following molecules are allowed to react under the following conditions: (v) H₂O; (vi) NaOH, H₂O. If there is no reaction, write 'no reaction.'

(f)

Textbook Question

Identify whether each of the following reactions proceed by an S_N1, S_N2, E1, or E2 mechanism.

(b)

Textbook Question

For which of the following reactions would you expect elimination to be more favored than substitution?

(a)

Textbook Question

For which of the following reactions would you expect elimination to be more favored than substitution?

(d)

Textbook Question

When the following compound undergoes solvolysis in ethanol, three products are obtained. Propose a mechanism to account for the formation of these products.

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Identify whether each of the following reactions proceed by an SN1, SN2, E1, or E2 mechanism.(c)

Key Concepts

Nucleophilic Substitution Mechanisms

Elimination Reactions

Factors Influencing Mechanism Choice

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Identify whether each of the following reactions proceed by an S_N1, S_N2, E1, or E2 mechanism.
(c)