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

7. Substitution Reactions

Good Leaving Groups

Organic Chemistry

7. Substitution Reactions

Good Leaving Groups

Previous problemNext problem

1:18 minutes

Problem 24a

Textbook Question

Formation of the carbocation should be fastest for which leaving group?
(a)

Verified step by step guidance

Identify the factors that influence the rate of carbocation formation. The rate of carbocation formation depends on the stability of the carbocation intermediate and the ability of the leaving group to depart. A good leaving group is one that can stabilize the negative charge after leaving.

Examine the leaving groups in the given options. A good leaving group is typically a weak base, as weak bases are more stable on their own. For example, halides like Cl⁻, Br⁻, and I⁻ are common leaving groups, with I⁻ being the best due to its larger size and better charge distribution.

Consider the stability of the carbocation formed after the leaving group departs. Carbocation stability increases in the order: methyl < primary < secondary < tertiary. Additionally, resonance stabilization or inductive effects can further stabilize the carbocation.

Compare the leaving groups in the given options based on their ability to leave and the stability of the resulting carbocation. The leaving group that departs most easily and forms the most stable carbocation will result in the fastest carbocation formation.

Conclude which leaving group leads to the fastest carbocation formation by combining the analysis of leaving group ability and carbocation stability. Ensure to consider both steric and electronic effects in your evaluation.

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 can be formed during various organic reactions. Their stability is influenced by the degree of substitution; tertiary carbocations are more stable than secondary, which are more stable than primary. This stability affects the rate of formation, as more stable carbocations can form more readily, making them crucial in determining the fastest reaction pathway.

Leaving Groups

A leaving group is an atom or group that can depart from the parent molecule during a chemical reaction, taking with it the electrons from the bond. The ability of a leaving group to stabilize the negative charge after departure is key; good leaving groups, such as halides or sulfonates, are typically weak bases. The quality of the leaving group directly impacts the rate of carbocation formation.

Reaction Mechanisms

Understanding reaction mechanisms is essential for predicting how and why reactions occur. In the context of carbocation formation, mechanisms such as SN1 and SN2 illustrate how the leaving group influences the rate of reaction. The SN1 mechanism, which involves the formation of a carbocation intermediate, highlights the importance of both the stability of the carbocation and the nature of the leaving group in determining reaction speed.

Watch next

Master How to use the factors affecting acidity to predict leaving group ability. with a bite sized video explanation from Johnny

Start learning