Question 1

Bromination of benzene requires a Lewis acid catalyst while bromination of cyclohexene does not.Explain this difference in reactivity.

Accepted Answer

An alkene is a better nucleophile than benzene,and thus the Br-Br bond does not have to be weakened to form a better electrophile before reaction.

Question 2

Which of the following is not a correct statement about the electrophilic substitution mechanism of benzene?

Accepted Answer

D

Question 3

In the bromination of benzene using Br₂ and FeBr₃,is the intermediate carbocation aromatic? Explain.

Accepted Answer

No,the carbocation is not aromatic since the ring contains an sp³ center.

Question 4

Which of the following is the first step in the mechanism of bromination?

Accepted Answer

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Question 5

Provide a detailed,stepwise mechanism for the reaction of benzene with Br₂ and FeBr₃.Make sure to include the activating reaction between Br₂ and FeBr₃ in your mechanism.

Accepted Answer

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Question 6

What specific electrophile is attacked by benzene when it undergoes nitration?

Accepted Answer

In nitration, benzene attacks the nitronium ion (NO₂⁺), which is the active electrophile generated from the reaction of nitric acid and sulfuric acid.

Question 7

Draw benzyl bromide.

Accepted Answer

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Question 8

Provide the major resonance structures of the intermediate sigma complex in the reaction of benzene with the generic electrophile E⁺.

Accepted Answer

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Question 9

Why does benzene undergo electrophilic substitution rather than electrophilic addition?

Accepted Answer

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Question 10

Name the following compound.

Accepted Answer

The compound contains a hexane chain with a phenyl group attached to the second carbon atom, therefore it is 2-phenylhexane. None of the other options fit this structure.

Question 11

What purpose does FeCl₃ serve in the electrophilic aromatic substitution reaction between chlorine and benzene?

Accepted Answer

FeCl₃ serves as a Lewis acid catalyst by reacting with Cl₂ to generate an electrophile, the chloronium ion (Cl+). This activates the electrophile toward attack by the π electrons in the benzene ring, leading to the electrophilic aromatic substitution reaction.

Question 12

Provide the structure of benzenesulfonic acid.

Accepted Answer

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Question 13

Give the best product for the following reaction.

Accepted Answer

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Question 14

Which of the following is most likely to be the first step in the general mechanism for electrophilic substitution reactions?

Accepted Answer

The first step in the general mechanism for electrophilic substitution reactions is the generation of an electrophile, typically by protonation or coordination with a Lewis acid. In this case, step II shows the generation of an electrophile, which is the protonation of the benzene ring with H+ to form the intermediate carbocation.

Question 15

Which of the following is the electrophile that attacks the aromatic ring during nitration?

Accepted Answer

The electrophile that attacks the aromatic ring during nitration is the nitronium ion (NO2+), which is represented in option D.

Question 16

Which step in the general mechanism for electrophilic aromatic substitution is rate-determining? Explain.

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Question 17

What is the structure of styrene?

Accepted Answer

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...

Question 18

Which of the following is one of the resonance contributors of the intermediate produced in a Friedel-Crafts alkylation of benzene?

Accepted Answer

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Question 19

Provide the structure of dibenzyl ether.

Accepted Answer

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Question 20

Provide the structure of anisole.

Accepted Answer

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Quiz 18: Reactions of Benzene and Substituted Benzenes