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

Electron Withdrawing Groups

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

Electron Withdrawing Groups

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5:43 minutes

Problem 25e,f

Textbook Question

What is the major product(s) of each of the following reactions?
e. nitration of p-methoxybenzaldehyde
f. nitration of p-tert-butylmethylbenzene

Verified step by step guidance

Step 1: Understand the reaction type. Nitration is an electrophilic aromatic substitution reaction where a nitro group (-NO₂) is introduced to the aromatic ring. The reaction typically involves a mixture of concentrated nitric acid (HNO₃) and sulfuric acid (H₂SO₄) as the nitrating agent.

Step 2: Analyze the substituents on the aromatic ring for each compound. For p-methoxybenzaldehyde, the substituents are a methoxy group (-OCH₃) and an aldehyde group (-CHO). For p-tert-butylmethylbenzene, the substituents are a tert-butyl group (-C(CH₃)₃) and a methyl group (-CH₃).

Step 3: Determine the directing effects of the substituents. The methoxy group (-OCH₃) is an electron-donating group and an ortho/para-director, while the aldehyde group (-CHO) is an electron-withdrawing group and a meta-director. In p-tert-butylmethylbenzene, both the tert-butyl group and the methyl group are electron-donating and ortho/para-directors.

Step 4: Predict the major product for p-methoxybenzaldehyde. The methoxy group is a stronger activator than the aldehyde group, so it will dominate the directing effects. The nitro group will preferentially add to the ortho or para position relative to the methoxy group. However, the para position is already occupied by the aldehyde group, so the nitro group will add to the ortho position relative to the methoxy group.

Step 5: Predict the major product for p-tert-butylmethylbenzene. Both substituents are ortho/para-directors, but steric hindrance plays a role. The nitro group will preferentially add to the position that is para to the tert-butyl group, as this position is less sterically hindered compared to the ortho positions.

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Key Concepts

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

Electrophilic Aromatic Substitution

Electrophilic aromatic substitution (EAS) is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. This process is crucial for understanding how substituents on the ring influence the reactivity and orientation of further substitutions. The nature of the substituents, whether they are electron-donating or electron-withdrawing, significantly affects the position where the electrophile will attack.

Nitration Reaction

Nitration is a specific type of electrophilic aromatic substitution where a nitro group (NO2) is introduced into an aromatic compound. This reaction typically involves the use of a nitrating mixture, such as concentrated nitric acid and sulfuric acid, which generates the nitronium ion (NO2+), the active electrophile. The position of nitration is influenced by existing substituents on the aromatic ring, which can direct the electrophile to ortho, meta, or para positions.

Substituent Effects on Aromatic Compounds

Substituent effects refer to how different groups attached to an aromatic ring can influence the reactivity and orientation of electrophilic substitutions. Electron-donating groups, like methoxy (-OCH3), activate the ring and direct incoming electrophiles to the ortho and para positions, while electron-withdrawing groups, like carbonyls, can deactivate the ring and direct electrophiles to the meta position. Understanding these effects is essential for predicting the major products of nitration reactions.

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