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

Previous problemNext problem

Problem 6b

Textbook Question

Identify the more stable carbocation in each pair.
(b)

Verified step by step guidance

Step 1: Analyze the structure of each carbocation. The first carbocation is a tertiary carbocation (the positively charged carbon is attached to three other carbon atoms), while the second carbocation is a secondary carbocation (the positively charged carbon is attached to two other carbon atoms).

Step 2: Recall the concept of carbocation stability. Carbocations are stabilized by the inductive effect and hyperconjugation. Tertiary carbocations are more stable than secondary carbocations because they have more alkyl groups donating electron density to the positively charged carbon.

Step 3: Consider hyperconjugation. The tertiary carbocation has more adjacent C-H bonds that can participate in hyperconjugation, further stabilizing the positive charge.

Step 4: Evaluate the inductive effect. The tertiary carbocation benefits from the electron-donating effects of three alkyl groups, whereas the secondary carbocation only has two alkyl groups contributing to stabilization.

Step 5: Conclude that the tertiary carbocation is more stable than the secondary carbocation based on the combined effects of hyperconjugation and the inductive effect.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Play a video:

Was this helpful?

Key Concepts

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

Carbocation Stability

Carbocations are positively charged carbon species that can vary in stability based on their structure. Stability increases with the degree of substitution; tertiary carbocations (three alkyl groups attached) are more stable than secondary (two alkyl groups) and primary (one alkyl group) due to hyperconjugation and inductive effects from surrounding alkyl groups.

Hyperconjugation

Hyperconjugation is the stabilizing interaction that occurs when the electrons in a sigma bond (usually 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.

Inductive Effect

The inductive effect refers to the electron-withdrawing or electron-donating effects of substituents attached to a carbon chain. Alkyl groups are electron-donating, which can help stabilize a carbocation by dispersing the positive charge through the sigma bonds, making carbocations with more alkyl groups attached more stable.

Watch next

Master Determining Carbocation Stability with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

For each pair of reactions, predict which will happen more quickly. [For (c) and (d), the more substituted carbocation is more stable due to hyperconjugation.]

(c)