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

4:40 minutes

Problem 42

Textbook Question

List the following carbocations in decreasing order of their stability.

Verified step by step guidance

Step 1: Analyze the stability of carbocations based on their structure. Carbocation stability is influenced by factors such as hyperconjugation, resonance, and inductive effects. Tertiary carbocations are generally more stable than secondary, which are more stable than primary carbocations.

Step 2: Examine the first structure. The carbocation is tertiary because the positively charged carbon is attached to three other carbons, including a methyl group. This structure benefits from hyperconjugation and inductive effects, making it highly stable.

Step 3: Examine the second structure. The carbocation is primary because the positively charged carbon is attached to only one other carbon. This structure lacks significant stabilizing effects, making it less stable.

Step 4: Examine the third structure. The carbocation is primary, but it is adjacent to a double bond, allowing for resonance stabilization. The positive charge can delocalize over the π-electrons of the double bond, increasing its stability compared to a simple primary carbocation.

Step 5: Examine the fourth structure. The carbocation is tertiary and adjacent to a double bond. This structure benefits from both hyperconjugation and resonance stabilization, making it the most stable among the given carbocations.

Verified video answer for a similar problem:

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

Video duration:

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 are classified based on their degree of substitution: primary, secondary, and tertiary. Tertiary carbocations are the most stable due to hyperconjugation and the inductive effect from surrounding alkyl groups, which help to disperse the positive charge. In contrast, primary carbocations are the least stable, as they have fewer alkyl groups to stabilize the charge.

Hyperconjugation

Hyperconjugation is a stabilizing interaction that occurs when the electrons in a sigma bond (usually C-H or C-C) interact with an adjacent empty p-orbital or a positively charged carbon. This interaction allows for the delocalization of charge, which stabilizes the carbocation. The more alkyl groups attached to the carbocation, the greater the hyperconjugation effect, leading to increased stability.

Inductive Effect

The inductive effect refers to the electron-donating or electron-withdrawing effects transmitted through sigma bonds in a molecule. Alkyl groups are electron-donating, which helps to stabilize a positive charge on a carbocation. The presence of more alkyl substituents increases the overall electron density around the carbocation, enhancing its stability compared to less substituted carbocations.

Watch next

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

Start learning