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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5:12 minutes

Problem 54c

Textbook Question

Predict the major products of bromination of the following compounds, using Br2 and FeBr3 in the dark.
(c)

Verified step by step guidance

Step 1: Analyze the structure of the compound. The molecule contains two aromatic rings connected by a ketone group (C=O). Each aromatic ring has a methoxy group (-OCH3) attached. The methoxy group is an electron-donating group, which activates the aromatic ring towards electrophilic substitution reactions, such as bromination.

Step 2: Understand the reaction conditions. Bromination using Br2 and FeBr3 in the dark is an electrophilic aromatic substitution reaction. FeBr3 acts as a Lewis acid catalyst, facilitating the generation of the bromonium ion (Br+), which is the electrophile in this reaction.

Step 3: Determine the directing effects of substituents. The methoxy group (-OCH3) is an ortho/para-directing group due to its electron-donating nature. This means bromination will preferentially occur at the ortho and para positions relative to the methoxy group on each aromatic ring.

Step 4: Predict the major products. Bromination will occur at the most activated positions on the aromatic rings. For the ring with the methoxy group, the ortho and para positions relative to the -OCH3 group are the most reactive. Since both rings have methoxy groups, bromination can occur at these positions on both rings.

Step 5: Consider steric hindrance and regioselectivity. The para position relative to the methoxy group is less sterically hindered compared to the ortho positions. Therefore, bromination is more likely to occur at the para position on each aromatic ring, leading to the major products being para-brominated derivatives of the original compound.

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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. In this process, the aromatic system donates electrons to the electrophile, forming a sigma complex, which then loses a proton to restore aromaticity. Understanding EAS is crucial for predicting the products of bromination, as it involves the interaction of the aromatic compound with bromine in the presence of a catalyst.

Activating and Deactivating Groups

In EAS reactions, substituents on the aromatic ring can either activate or deactivate the ring towards further substitution. Activating groups, such as -OCH3, increase the electron density of the ring, making it more reactive towards electrophiles. Conversely, deactivating groups, like -COOH, withdraw electron density and make the ring less reactive. Recognizing the nature of substituents is essential for predicting the position and rate of bromination in the given compound.

Regioselectivity in Bromination

Regioselectivity refers to the preference of a chemical reaction to occur at one location over others in a molecule. In the case of bromination of aromatic compounds, the presence of activating or deactivating groups influences where the bromine will add to the ring. For the compound shown, the methoxy groups will direct bromination to the ortho and para positions relative to themselves, which is critical for predicting the major products of the reaction.

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For each of the statements in Column I, choose a substituent from Column II that fits the description for the compound on the right:

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Predict the site(s) of electrophilic attack on these compounds.

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Predict the major products of bromination of the following compounds, using Br₂ and FeBr₃ in the dark.

(a)

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Predict the major products of bromination of the following compounds, using Br₂ and FeBr₃ in the dark.

(b)

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Predict the major products formed when benzene reacts (just once) with the following reagents.

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Biphenyl is two benzene rings joined by a single bond. The site of substitution for a biphenyl is determined by (1) which phenyl ring is more activated (or less deactivated), and (2) which position on that ring is most reactive, using the fact that a phenyl substituent is activating and ortho, para-directing.

a. Use resonance forms of a sigma complex to show why a phenyl substituent should be ortho, para-directing.

(i)

Textbook Question

b. Predict the mononitration products of the following compounds

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b. Predict the mononitration products of the following compounds

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