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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4:20 minutes

Problem 51a

Textbook Question

For each set of reactive intermediates, rank them in order of reactivity (1 = most reactive).
(a)

Verified step by step guidance

Step 1: Understand the concept of reactive intermediates. Reactive intermediates are short-lived, high-energy species formed during chemical reactions. Common types include carbocations, carbanions, free radicals, and carbenes. Their reactivity depends on factors such as stability, electronic structure, and the ability to participate in reactions.

Step 2: Identify the reactive intermediates provided in the problem. For example, if the intermediates are carbocations, consider their stability based on the number of alkyl groups attached to the positively charged carbon (tertiary > secondary > primary > methyl). If they are free radicals, analyze their stability similarly.

Step 3: Apply the concept of stabilization factors. For carbocations, hyperconjugation and resonance stabilize the intermediate. For carbanions, electron-withdrawing groups stabilize the negative charge. For free radicals, resonance and hyperconjugation also play a role. Rank the intermediates based on these stabilization factors.

Step 4: Consider steric effects and electronic effects. Steric hindrance can reduce reactivity, while electronic effects such as inductive effects can either stabilize or destabilize the intermediate. Use these considerations to refine the ranking.

Step 5: Rank the intermediates in order of reactivity (1 = most reactive). The most reactive intermediate is typically the least stable, as it is more eager to participate in a reaction to achieve stability. Ensure the ranking aligns with the principles discussed in the previous steps.

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Key Concepts

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

Reactive Intermediates

Reactive intermediates are transient species that form during the course of a chemical reaction. They include carbocations, carbanions, and free radicals, each possessing unique stability and reactivity characteristics. Understanding the nature of these intermediates is crucial, as their stability directly influences the rate and pathway of the reaction.

Stability of Intermediates

The stability of reactive intermediates is determined by factors such as hybridization, resonance, and inductive effects. For example, tertiary carbocations are more stable than primary ones due to greater hyperconjugation and inductive effects from surrounding alkyl groups. This stability hierarchy is essential for predicting the reactivity of different intermediates.

Reactivity Trends

Reactivity trends in organic chemistry often follow the principle that less stable intermediates are more reactive. For instance, free radicals are generally more reactive than stable carbocations due to their incomplete octet. Recognizing these trends allows chemists to rank intermediates based on their likelihood to participate in subsequent reactions.

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