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

1. A Review of General Chemistry

Resonance Structures

Organic Chemistry

1. A Review of General Chemistry

Resonance Structures

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5:07 minutes

Problem 24a

Textbook Question

3-Bromocyclohexene is a secondary halide. It undergoes S_N1 substitution about as fast as most tertiary halides. Use resonance structures to explain this enhanced reactivity.

Verified step by step guidance

Identify the structure of 3-bromocyclohexene, which consists of a cyclohexene ring with a bromine atom attached to the third carbon.

Recognize that the presence of the double bond in the cyclohexene ring allows for resonance stabilization of the carbocation formed during the SN1 reaction.

Draw the resonance structures: When the bromine leaves, a carbocation is formed at the third carbon. The positive charge can be delocalized to the adjacent carbon atoms through resonance with the double bond.

Illustrate the movement of electrons: The pi electrons from the double bond can move to form a new double bond with the carbocation, shifting the positive charge to the other carbon atom in the ring.

Explain that this resonance stabilization of the carbocation intermediate makes the SN1 reaction more favorable, enhancing the reactivity of 3-bromocyclohexene compared to other secondary halides without such stabilization.

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Key Concepts

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

SN1 Reaction Mechanism

The SN1 reaction mechanism involves a two-step process where the leaving group departs first, forming a carbocation intermediate, followed by nucleophilic attack. The rate of SN1 reactions depends on the stability of the carbocation; more stable carbocations lead to faster reactions. This mechanism is common in tertiary halides due to their ability to stabilize positive charges.

Carbocation Stability

Carbocation stability is crucial in determining the rate of SN1 reactions. Stability is enhanced by factors such as hyperconjugation and resonance. Tertiary carbocations are generally more stable than secondary or primary ones due to greater hyperconjugation and inductive effects. In 3-bromocyclohexene, resonance stabilization plays a key role in enhancing carbocation stability.

Resonance Structures

Resonance structures are different Lewis structures for a molecule that depict the delocalization of electrons. In 3-bromocyclohexene, the positive charge on the carbocation can be delocalized over the double bond, creating resonance structures that stabilize the intermediate. This delocalization increases the carbocation's stability, making the SN1 reaction proceed more rapidly, similar to tertiary halides.

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Master The rules you need for resonance: with a bite sized video explanation from Johnny

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3-Bromocyclohexene is a secondary halide. It undergoes SN1 substitution about as fast as most tertiary halides. Use resonance structures to explain this enhanced reactivity.

Key Concepts

SN1 Reaction Mechanism

Carbocation Stability

Resonance Structures

Watch next

3-Bromocyclohexene is a secondary halide. It undergoes S_N1 substitution about as fast as most tertiary halides. Use resonance structures to explain this enhanced reactivity.