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

6. Thermodynamics and Kinetics

Carbocation Stability

Organic Chemistry

6. Thermodynamics and Kinetics

Carbocation Stability

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3:42 minutes

Problem 2b

Textbook Question

Which is more stable: a methyl cation or an ethyl cation? Why?

Verified step by step guidance

Step 1: Understand the concept of carbocation stability. Carbocations are positively charged carbon species, and their stability is influenced by factors such as hyperconjugation, inductive effects, and resonance.

Step 2: Analyze the structure of a methyl cation (CH₃⁺). A methyl cation has no alkyl groups attached to the positively charged carbon, meaning it lacks hyperconjugation and inductive stabilization. It is highly unstable.

Step 3: Analyze the structure of an ethyl cation (CH₃CH₂⁺). The ethyl cation has one alkyl group (a methyl group) attached to the positively charged carbon. This methyl group provides hyperconjugation and inductive effects, which help stabilize the positive charge.

Step 4: Compare the two carbocations. The ethyl cation is more stable than the methyl cation because the methyl group in the ethyl cation donates electron density through hyperconjugation and inductive effects, reducing the electron deficiency of the positively charged carbon.

Step 5: Conclude that the ethyl cation is more stable than the methyl cation due to the stabilizing effects of the attached alkyl group, which are absent in the methyl cation.

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Key Concepts

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

Carbocation Stability

Carbocation stability is influenced by the degree of alkyl substitution. Tertiary carbocations are more stable than secondary, which are more stable than primary, due to hyperconjugation and inductive effects. The presence of alkyl groups can donate electron density to the positively charged carbon, stabilizing the cation.

Hyperconjugation

Hyperconjugation is a stabilizing interaction that occurs when the electrons in a sigma bond (C-H or C-C) interact with an adjacent empty p-orbital of a carbocation. This delocalization of electrons helps to spread out the positive charge, thereby increasing the stability of the carbocation. More alkyl groups lead to more hyperconjugative interactions.

Inductive Effect

The inductive effect refers to the electron-withdrawing or electron-donating effects of substituents through sigma bonds. Alkyl groups are electron-donating, which can help stabilize a positive charge in a carbocation. The more alkyl groups attached to the cation, the greater the inductive stabilization, making the cation more stable.

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