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

Enolate

Organic Chemistry

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Enolate

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1:36 minutes

Problem 3d

Textbook Question

Give the important resonance forms for the possible enolate ions of the following:
(d)

Verified step by step guidance

Identify the alpha hydrogens in the molecule. Alpha hydrogens are the hydrogens attached to the carbon atoms adjacent to the carbonyl group. In this case, the alpha carbons are the ones directly connected to the carbonyl carbon.

Determine the possible enolate ions that can form by deprotonating the alpha hydrogens. Deprotonation leads to the formation of a carbanion at the alpha carbon, which is stabilized by resonance with the carbonyl group.

Draw the resonance structures for each enolate ion. The negative charge on the alpha carbon can delocalize onto the oxygen atom of the carbonyl group, forming a resonance structure where the oxygen has a negative charge and the alpha carbon has a double bond with the carbonyl carbon.

Consider the stereochemistry and structure of the molecule. The molecule has two distinct alpha carbons (one on the cyclopentane ring and one on the ethyl group). Each alpha carbon can form its own enolate ion, and each enolate ion will have its own set of resonance structures.

Ensure that all resonance structures obey the rules of resonance, such as maintaining the octet rule for all atoms involved and properly delocalizing the electrons. Label the resonance structures to show the movement of electrons and the stabilization of the enolate ion.

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Key Concepts

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

Enolate Ions

Enolate ions are reactive intermediates formed from the deprotonation of a carbonyl compound, typically a ketone or aldehyde. They contain a negatively charged carbon atom adjacent to a carbonyl group, which allows for resonance stabilization. This resonance can lead to different structural forms, influencing the reactivity and stability of the enolate in various organic reactions.

Resonance Structures

Resonance structures are different Lewis structures for the same molecule that depict the delocalization of electrons. In the case of enolate ions, resonance allows the negative charge to be shared between the carbon atom and the oxygen atom of the carbonyl group. This delocalization stabilizes the enolate ion and is crucial for understanding its reactivity in nucleophilic addition and other reactions.

Carbonyl Compounds

Carbonyl compounds, characterized by the presence of a carbon-oxygen double bond (C=O), include aldehydes, ketones, and carboxylic acids. They are key substrates in organic chemistry, particularly in reactions involving enolate ions. Understanding the structure and reactivity of carbonyl compounds is essential for predicting the behavior of enolates and their resonance forms in various chemical transformations.

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Related Practice

Textbook Question

Show the resonance forms for the enolate ions that result when the following compounds are treated with a strong base.

(d) nitroacetone

Textbook Question

For each molecule shown below,

1. indicate the most acidic hydrogens.

2. draw the important resonance contributors of the anion that results from removal of the most acidic hydrogen.

(g)

Textbook Question

For each molecule shown below,

1. indicate the most acidic hydrogens.

2. draw the important resonance contributors of the anion that results from removal of the most acidic hydrogen.

(h)

Textbook Question

Give the important resonance forms for the possible enolate ions of the following:

Textbook Question

Give the important resonance forms for the possible enolate ions of the following:

(e)

Textbook Question

Give the important resonance forms for the possible enolate ions of the following:

(f)

Textbook Question

Show the resonance forms for the enolate ions that result when the following compounds are treated with a strong base.

(a) ethyl acetoacetate

(b) pentane-2,4-dione

Textbook Question

When cis-2,4-dimethylcyclohexanone is dissolved in aqueous ethanol containing a trace of NaOH, a mixture of cis and trans isomers results. Propose a mechanism for this isomerization.

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Give the important resonance forms for the possible enolate ions of the following:(d)

Key Concepts

Enolate Ions

Resonance Structures

Carbonyl Compounds

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Give the important resonance forms for the possible enolate ions of the following:
(d)