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

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9:08 minutes

Problem 1

Textbook Question

Rank the following anions based on their stability as potential leaving groups. Explain your reasoning (1 = most stable ; 5 = least stable).

Verified step by step guidance

Identify the anions provided in the problem. Common leaving groups include halides (e.g., Cl⁻, Br⁻, I⁻), hydroxide (OH⁻), and others. Stability as a leaving group is often related to the ability of the anion to stabilize negative charge.

Recall the general trend for leaving group stability: the better the leaving group, the more stable the anion. Stability is influenced by factors such as electronegativity, size, resonance stabilization, and inductive effects.

Compare the electronegativity of the atoms in the anions. More electronegative atoms stabilize negative charge better, making the anion a better leaving group. For example, I⁻ is more stable than Cl⁻ because iodine is larger and can better disperse the negative charge.

Consider resonance effects. Anions that can delocalize their negative charge through resonance are more stable. For example, a carboxylate ion (RCOO⁻) is more stable than a hydroxide ion (OH⁻) due to resonance stabilization.

Evaluate inductive effects. Electronegative atoms or groups near the negative charge can stabilize the anion through electron withdrawal. For example, trifluoromethanesulfonate (CF₃SO₃⁻) is highly stable due to the strong electron-withdrawing effect of the fluorine atoms.

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Key Concepts

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

Leaving Group Ability

Leaving group ability refers to the tendency of an atom or group of atoms to depart from a molecule during a chemical reaction. A good leaving group is typically stable after departure, often being a weak base. Common examples include halides and sulfonate groups, which can stabilize the negative charge effectively, making them favorable in nucleophilic substitution reactions.

Anion Stability

Anion stability is influenced by several factors, including electronegativity, resonance, and the size of the atom bearing the negative charge. Generally, larger anions can better stabilize negative charges due to their ability to spread out the charge over a larger volume. Additionally, resonance can delocalize the negative charge, further enhancing stability.

Electronegativity and Charge Distribution

Electronegativity is the tendency of an atom to attract electrons towards itself. In the context of anions, more electronegative atoms can stabilize negative charges more effectively. When ranking anions, those with higher electronegativity may be less stable as leaving groups compared to those that can distribute the charge more evenly or are less electronegative, thus influencing their overall stability.

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