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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5:04 minutes

Problem 21a,b

Textbook Question

Give the products, if any, of each of the following reactions:
a. benzonitrile + methyl chloride + AlCl₃
b. phenol + Br₂

Verified step by step guidance

Step 1: For reaction (a), recognize that benzonitrile (C6H5CN) contains a nitrile group (-CN) attached to a benzene ring. The reaction involves methyl chloride (CH3Cl) and aluminum chloride (AlCl3), which is a Lewis acid catalyst. This setup suggests a Friedel-Crafts alkylation reaction. However, the nitrile group is an electron-withdrawing group, which deactivates the benzene ring and makes it less reactive toward electrophilic substitution. Therefore, no reaction occurs in this case.

Step 2: For reaction (b), phenol (C6H5OH) contains a hydroxyl group (-OH) attached to a benzene ring. The hydroxyl group is an electron-donating group, which activates the benzene ring toward electrophilic substitution, especially at the ortho and para positions.

Step 3: Bromine (Br2) is the electrophile in this reaction. In the presence of phenol, bromine reacts readily without the need for a catalyst. The hydroxyl group directs the bromine to the ortho and para positions on the benzene ring.

Step 4: The reaction typically results in the formation of 2-bromophenol (ortho product) and 4-bromophenol (para product). However, under excess bromine, further substitution can occur, leading to the formation of 2,4,6-tribromophenol as the major product.

Step 5: Summarize the outcomes: (a) No reaction occurs due to the deactivating effect of the nitrile group. (b) Phenol reacts with bromine to form brominated products, with 2,4,6-tribromophenol being the major product under excess bromine.

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Key Concepts

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

Friedel-Crafts Alkylation

This is a reaction where an alkyl group is introduced to an aromatic ring using an alkyl halide and a Lewis acid catalyst, such as AlCl3. In the case of benzonitrile and methyl chloride, the AlCl3 activates the methyl chloride, allowing it to react with the aromatic system of benzonitrile, potentially leading to the formation of a methyl-substituted product.

Electrophilic Aromatic Substitution

This is a fundamental mechanism in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. In the reaction of phenol with Br2, the hydroxyl group (–OH) activates the aromatic ring, making it more reactive towards electrophiles like bromine, resulting in brominated phenol products.

Reactivity of Aromatic Compounds

Aromatic compounds exhibit unique reactivity patterns due to their stable resonance structures. The presence of substituents, such as –CN in benzonitrile or –OH in phenol, can influence the reactivity and orientation of further substitutions, affecting the products formed in reactions with electrophiles like methyl chloride or bromine.