Question 1

Which of the following is NOT a requirement for aromaticity according to Hückel’s rule?

Accepted Answer

The molecule must have 4 π-electrons.

Question 2

What is the rate-determining step in the mechanism of electrophilic aromatic substitution (SEAr)?

Accepted Answer

Attack of the electrophile (E+) on the π-electron system of the aromatic ring.

Question 3

Which reagent is required for the bromination of benzene in an electrophilic aromatic substitution reaction?

Accepted Answer

FeBr3

Question 4

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

Accepted Answer

Nitronium ion $$\mathrm{NO_2$^+}$$

Question 5

Which of the following statements about Friedel-Crafts alkylation is TRUE?

Accepted Answer

Methyl, ethyl, allyl, and benzyl halides do not rearrange during Friedel-Crafts alkylation.

Question 6

Why do tertiary carbocation intermediates form faster than secondary ones during SEAr reactions?

Accepted Answer

Tertiary carbocations are more stable due to greater alkyl group electron donation.

Question 7

Which substituent is meta-directing and strongly deactivating in electrophilic aromatic substitution?

Accepted Answer

Nitro group ($$\mathrm{NO_2$})$$

Question 8

In the bromination of nitrobenzene, why is the meta product formed in higher yield than the ortho and para products?

Accepted Answer

The meta carbocation intermediate avoids destabilization from adjacent positive charges.

Question 9

Which of the following is a limitation of Friedel-Crafts alkylation?

Accepted Answer

Primary alkyl halides often lead to rearranged products.

Question 10

What is the main difference between the addition-elimination and elimination-addition mechanisms in nucleophilic aromatic substitution (SNAr)?

Accepted Answer

Addition-elimination requires electron-withdrawing groups, elimination-addition does not.

Question 11

Which group stabilizes the Meisenheimer complex most effectively in SNAr reactions?

Accepted Answer

Fluorine ($$\mathrm{F})$$

Question 12

What is the product of the reaction between chlorobenzene and sodium amide ($$\mathrm{$$NaNH_2$$}) in $$liquid ammonia?

Accepted Answer

Aniline ($$\mathrm{C_6H_5NH_2})$$

Question 13

Which of the following statements about aryl halides is correct?

Accepted Answer

Aryl halides require drastic conditions for nucleophilic substitution.

Question 14

Which factor determines the regioselectivity when electronic effects are similar in aromatic substitution?

Accepted Answer

Steric effects

Question 15

What is the effect of a methyl group on the rate and orientation of nitration in toluene?

Accepted Answer

Activates the ring and ortho/para-directs substitution.

Question 16

Which of the following is TRUE about the Friedel-Crafts acylation mechanism?

Accepted Answer

The acylium ion is stabilized by resonance and does not rearrange.

Question 17

In the synthesis of disubstituted aromatic compounds, why is the order of introduction of substituents important?

Accepted Answer

Because the first substituent determines the orientation of the second substitution.

Question 18

Which of the following is NOT a main example of electrophilic aromatic substitution (SEAr) reactions?

Accepted Answer

Hydrogenation

Question 19

What is the effect of the trifluoromethyl group ($$\mathrm{CF_3$}) on $$the rate and orientation of nitration in benzene?

Accepted Answer

Deactivates the ring and meta-directs substitution.

Reactions of Aromatic Compounds: Electrophilic and Nucleophilic Substitution

Study Guide - Practice Questions