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

26. Amines

Amine Alkylation

Organic Chemistry

26. Amines

Amine Alkylation

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2:46 minutes

Problem 33d

Textbook Question

Rank the amines in each set in order of increasing basicity.
(d)

Verified step by step guidance

Step 1: Analyze the chemical structures provided. The three amines are aniline derivatives, each with a substituent on the benzene ring: (a) aniline (NH₂ group attached to benzene), (b) methyl-substituted aniline (CH₃ group attached to benzene), and (c) nitro-substituted aniline (NO₂ group attached to benzene).

Step 2: Understand the effect of substituents on the basicity of the amine group. Substituents can either donate or withdraw electron density from the benzene ring, which affects the availability of the lone pair on the nitrogen atom for protonation.

Step 3: Evaluate the electron-donating or electron-withdrawing nature of each substituent. The methyl group (CH₃) is an electron-donating group via hyperconjugation and inductive effects, increasing the electron density on the nitrogen atom and enhancing basicity. The nitro group (NO₂) is a strong electron-withdrawing group due to resonance and inductive effects, decreasing the electron density on the nitrogen atom and reducing basicity.

Step 4: Rank the amines based on their substituents' effects. The unsubstituted aniline (NH₂ group only) has intermediate basicity. The methyl-substituted aniline is more basic due to the electron-donating effect of the CH₃ group. The nitro-substituted aniline is the least basic due to the electron-withdrawing effect of the NO₂ group.

Step 5: Final ranking in order of increasing basicity: Nitro-substituted aniline < Unsubstituted aniline < Methyl-substituted aniline.

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Key Concepts

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

Basicity of Amines

Basicity in amines refers to their ability to accept protons (H+) in a chemical reaction. This property is influenced by the availability of the lone pair of electrons on the nitrogen atom, which can bond with protons. Factors such as steric hindrance and the presence of electron-donating or withdrawing groups can significantly affect the basicity of different amines.

Inductive Effect

The inductive effect describes how the presence of electronegative atoms or groups near the amine can influence its basicity. Electron-withdrawing groups decrease basicity by stabilizing the lone pair on nitrogen, making it less available for protonation. Conversely, electron-donating groups enhance basicity by increasing electron density on nitrogen, facilitating proton acceptance.

Steric Hindrance

Steric hindrance refers to the repulsion between atoms due to their physical size, which can impede the approach of protons to the nitrogen atom in amines. In bulky amines, steric hindrance can reduce basicity as the nitrogen's lone pair becomes less accessible for bonding with protons. Understanding steric effects is crucial for ranking amines based on their basicity.

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Textbook Question

Basicity depends on availability of an electron pair to bond a proton. Correlate structural effects in these amines with their basicities.

(a) Explain this order:

Textbook Question

Basicity depends on availability of an electron pair to bond a proton. Correlate structural effects in these amines with their basicities.

(b) Explain:

Textbook Question

Basicity depends on availability of an electron pair to bond a proton. Correlate structural effects in these amines with their basicities.

(c) The pK_b of this compound is −2.3, making it not only a stronger base than a typical aniline, but even stronger than hydroxide ion. Explain its remarkable basicity.

Textbook Question

Within each structure, rank the indicated nitrogens by increasing basicity.

(f)

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Predict the products of the following reactions.

(d)

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