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

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Tautomers of Dicarbonyl Compounds

Organic Chemistry

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Tautomers of Dicarbonyl Compounds

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14:05 minutes

Problem 66b

Textbook Question

Rank these compounds in order of increasing enol content. In each case, draw the most stable enol.

Verified step by step guidance

Step 1: Understand the concept of enol content. Enol content refers to the proportion of a compound that exists in the enol form (a structure with a hydroxyl group directly attached to a double-bonded carbon). The stability of the enol form is influenced by factors such as hydrogen bonding, conjugation, and steric effects.

Step 2: Analyze compound E. Compound E has two ketone groups. The enol form can be stabilized by intramolecular hydrogen bonding between the hydroxyl group and the adjacent ketone oxygen. Draw the most stable enol form by converting one of the ketone groups into an enol.

Step 3: Analyze compound F. Compound F has a conjugated double bond adjacent to one of the ketone groups. The enol form can be stabilized by resonance between the hydroxyl group and the conjugated system. Draw the most stable enol form by converting the ketone group adjacent to the double bond into an enol.

Step 4: Analyze compound G. Compound G has two ketone groups and additional steric hindrance due to the methyl groups. The steric hindrance reduces the stability of the enol form. Draw the most stable enol form by converting one of the ketone groups into an enol, considering steric effects.

Step 5: Analyze compound H. Compound H has two ketone groups in a conjugated cyclic system. The enol form can be highly stabilized by resonance within the conjugated system. Draw the most stable enol form by converting one of the ketone groups into an enol, ensuring resonance stabilization. Rank the compounds in order of increasing enol content based on the stability of their enol forms.

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Key Concepts

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

Enol Tautomerism

Enol tautomerism is a chemical equilibrium between a keto form (a carbonyl compound) and its corresponding enol form (an alcohol with a double bond). The stability of each form depends on factors such as sterics, electronics, and hydrogen bonding. Understanding this concept is crucial for predicting the relative amounts of enol and keto forms in a compound.

Stability of Enols

The stability of enols can be influenced by factors such as substitution patterns, resonance, and steric hindrance. Enols that can participate in intramolecular hydrogen bonding or have electron-withdrawing groups nearby tend to be more stable. Recognizing these factors helps in ranking compounds based on their enol content.

Keto-Enol Equilibrium

Keto-enol equilibrium refers to the dynamic balance between the keto and enol forms of a compound. The position of this equilibrium can be affected by temperature, solvent, and the presence of catalysts. Understanding this equilibrium is essential for determining which compounds will have higher enol content and for drawing the most stable enol structures.

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