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

19. Reactions of Aromatics: EAS and Beyond

Diazo Replacement Reactions

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

Diazo Replacement Reactions

Previous problemNext problem

Problem 33

Textbook Question

In the mechanism for electrophilic aromatic substitution with a diazonium ion as the electrophile, why does nucleophilic attack occur on the terminal nitrogen of the diazonium ion rather than on the nitrogen that has the formal positive charge?

Verified step by step guidance

Understand the structure of the diazonium ion: A diazonium ion has the general structure R-N≡N⁺, where the nitrogen with the formal positive charge is directly bonded to the aromatic ring (R), and the terminal nitrogen is triple-bonded to it.

Recognize the electrophilic nature of the diazonium ion: The diazonium ion is an electrophile because the positive charge on the nitrogen makes the molecule electron-deficient, and it seeks electrons from a nucleophile (in this case, the aromatic ring).

Analyze the electron density distribution: The triple bond between the two nitrogens in the diazonium ion is highly polarized. The terminal nitrogen is more electron-deficient because it is directly bonded to the positively charged nitrogen, which pulls electron density away from it. This makes the terminal nitrogen the most electrophilic site.

Consider steric and electronic factors: The nitrogen with the formal positive charge is directly bonded to the aromatic ring, which creates steric hindrance and reduces its accessibility for nucleophilic attack. Additionally, the terminal nitrogen is more accessible for the nucleophile.

Conclude why the terminal nitrogen is attacked: The nucleophilic aromatic ring attacks the terminal nitrogen because it is the most electrophilic site due to electron deficiency and is sterically more accessible compared to the nitrogen with the formal positive charge.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Play a video:

Was this helpful?

Key Concepts

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

Electrophilic Aromatic Substitution (EAS)

Electrophilic Aromatic Substitution is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. This process involves the formation of a sigma complex, where the aromaticity of the ring is temporarily lost. Understanding EAS is crucial for analyzing how different electrophiles, such as diazonium ions, interact with aromatic compounds.

Diazonium Ion Structure

Diazonium ions are a class of electrophiles characterized by a positively charged nitrogen atom bonded to a nitrogen double bond (N≡N). The terminal nitrogen, which is not positively charged, is more nucleophilic due to its ability to donate electrons. Recognizing the structure and reactivity of diazonium ions helps explain why nucleophilic attack occurs preferentially at the terminal nitrogen.

Nucleophilicity and Electrophilicity

Nucleophilicity refers to the ability of a species to donate an electron pair, while electrophilicity is the ability to accept an electron pair. In the context of the diazonium ion, the terminal nitrogen is more nucleophilic than the positively charged nitrogen, making it a more favorable site for nucleophilic attack. Understanding these concepts is essential for predicting the outcomes of reactions involving electrophiles and nucleophiles.

Watch next

Master Replacement Reactions with a bite sized video explanation from Johnny

Start learning