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

3. Acids and Bases

Reaction Mechanism

Organic Chemistry

3. Acids and Bases

Reaction Mechanism

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Problem 4c

Textbook Question

Based on the analysis you used in Assessment 17.3, which carbonyl would you expect to react most quickly with a nucleophile?
(c)

Verified step by step guidance

Analyze the two carbonyl compounds provided in the image. The first compound has an alkene group adjacent to the carbonyl, while the second compound has an alkyl group adjacent to the carbonyl.

Understand the concept of electronic effects. The alkene group in the first compound can exert a conjugative effect (resonance) with the carbonyl group, stabilizing the partial positive charge on the carbonyl carbon. This makes the carbonyl less electrophilic and less reactive toward nucleophiles.

Compare steric effects. The alkyl group in the second compound is bulkier than the alkene group in the first compound, which can hinder nucleophilic attack due to steric hindrance. However, steric effects are secondary to electronic effects in this case.

Determine the reactivity of the carbonyl groups. The carbonyl in the second compound is more electrophilic because it lacks the conjugative stabilization present in the first compound. This makes it more reactive toward nucleophiles.

Conclude that the carbonyl in the second compound (with the alkyl group) would react more quickly with a nucleophile compared to the carbonyl in the first compound (with the alkene group).

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Key Concepts

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

Nucleophilic Addition to Carbonyls

Nucleophilic addition is a fundamental reaction in organic chemistry where a nucleophile attacks the electrophilic carbon of a carbonyl group (C=O). The reactivity of carbonyl compounds varies based on the substituents attached to the carbonyl carbon, influencing the electron density and steric hindrance. Understanding this concept is crucial for predicting which carbonyl compound will react more quickly with a nucleophile.

Electrophilicity of Carbonyls

The electrophilicity of a carbonyl carbon is determined by the partial positive charge it carries due to the electronegativity of the oxygen atom. Factors such as resonance and inductive effects from substituents can either stabilize or destabilize this positive charge, affecting the carbonyl's reactivity. A more electrophilic carbonyl will react faster with nucleophiles, making this concept essential for analyzing the question.

Steric Hindrance

Steric hindrance refers to the repulsion between atoms that occurs when they are brought close together, which can impede reactions. In the context of carbonyl compounds, bulky groups near the carbonyl can hinder the approach of nucleophiles, slowing down the reaction. Evaluating the steric environment around the carbonyl is vital for determining which compound will react more quickly with a nucleophile.

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Related Practice

Textbook Question

Provide a reasonable arrow-pushing mechanism for the following Lewis acid–Lewis base reactions.

(a)

Textbook Question

Provide an arrow-pushing mechanism for the following hypothetical base half-reactions.

(b)

Textbook Question

BCl₃ has an empty p orbital, so it is a strong Lewis acid. Would you expect an amide to react with BCl₃ at nitrogen or oxygen?

Textbook Question

In each case, circle the stronger nucleophile.

(b)

Textbook Question

Classify the following nucleophiles as strong, weak, or intermediate. Would you expect each to add to a carbonyl directly or wait for a carbocation to form?

Textbook Question

Would you expect a ketone or an ester to be more reactive with a strong nucleophile? Justify your answer.

Textbook Question

Rank the reactivity of the following carbonyls with nucleophiles, from least reactive to most reactive.

Textbook Question

The following reaction steps are shown using conventional electron pushing. (a) Draw the second product whose formation would have been rationalized with this same arrow.

(a)

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Based on the analysis you used in Assessment 17.3, which carbonyl would you expect to react most quickly with a nucleophile?(c)

Key Concepts

Nucleophilic Addition to Carbonyls

Electrophilicity of Carbonyls

Steric Hindrance

Watch next

Based on the analysis you used in Assessment 17.3, which carbonyl would you expect to react most quickly with a nucleophile?
(c)