Question 1

Which of the following best describes the role of a Lewis acid such as FeCl$$_3 in $$the halogenation of benzene?

Accepted Answer

It polarizes the halogen molecule, generating a more powerful electrophile.

Question 2

During the nitration of benzene, which species acts as the electrophile?

Accepted Answer

NO$$_2^+$$

Question 3

What is the major product when toluene (methylbenzene) is treated with Br$$_2$$ and FeBr$$_3$$?

Accepted Answer

Ortho-bromotoluene

Question 4

Which of the following statements about the mechanism of electrophilic aromatic substitution is correct?

Accepted Answer

Arenium ion formation involves the addition of the electrophile to the aromatic ring, temporarily disrupting aromaticity.

Question 5

Why is Friedel–Crafts alkylation not effective with vinyl or aryl halides?

Accepted Answer

Vinyl and aryl carbocations are not sufficiently stable to form under reaction conditions.

Question 6

Which of the following groups is a strong activator and ortho/para director in electrophilic aromatic substitution?

Accepted Answer

$$-NH_2$

Question 7

A benzene ring with a nitro group undergoes bromination. Where does the bromine predominantly add?

Accepted Answer

Meta to the nitro group

Question 8

Which of the following is a limitation of Friedel–Crafts alkylation reactions?

Accepted Answer

They cannot be performed on rings with strong electron-withdrawing groups.

Question 9

What is the purpose of using fuming sulfuric acid in the sulfonation of benzene?

Accepted Answer

To generate a more powerful electrophile, SO$$_3$$

Question 10

Which of the following best explains why halogens are ortho/para directors but deactivating in electrophilic aromatic substitution?

Accepted Answer

Their inductive withdrawal outweighs their resonance donation, but resonance still stabilizes ortho/para intermediates.

Question 11

A student wants to synthesize m-bromonitrobenzene from benzene. Which sequence of reactions is most appropriate?

Accepted Answer

Nitration, then bromination

Question 12

Which of the following statements about the Clemmensen reduction is correct?

Accepted Answer

It reduces aryl ketones to alkylbenzenes using Zn(Hg) and HCl.

Question 13

Which of the following is required for a nucleophilic aromatic substitution (SNAr) to occur?

Accepted Answer

A strong electron-withdrawing group ortho or para to the leaving group

Question 14

Which of the following best describes the intermediate formed during the nitration of benzene?

Accepted Answer

A sigma complex (arenium ion)

Question 15

Why is the para product generally favored over the ortho product in the nitration of anisole?

Accepted Answer

The para position is less sterically hindered.

Question 16

Which of the following is a correct statement about the use of blocking groups in aromatic synthesis?

Accepted Answer

Blocking groups are used to temporarily prevent substitution at certain positions.

Question 17

A benzene ring with a methyl group and a nitro group is nitrated. Where will the new nitro group most likely be introduced?

Accepted Answer

Meta to the nitro group

Question 18

Which of the following is a reason why polyalkylation is a problem in Friedel–Crafts alkylation?

Accepted Answer

Alkyl groups activate the ring toward further alkylation.

Question 19

Which of the following best explains why the acylation of benzene does not result in polyacylation?

Accepted Answer

The acyl group deactivates the ring toward further electrophilic substitution.

Question 20

Which of the following is the correct order of reactivity toward electrophilic aromatic substitution (from most to least reactive)?

Accepted Answer

Toluene \u003e Benzene \u003e Nitrobenzene

Reactions of Aromatic Compounds: Electrophilic Aromatic Substitution and Substituent Effects

Study Guide - Practice Questions