Question 1

Which statement best explains why Friedel-Crafts alkylation reactions are inefficient on benzene rings with strong deactivating groups?

Accepted Answer

Deactivating groups lower the electron density of the ring, making it less reactive toward electrophiles.

Question 2

In nucleophilic aromatic substitution, which arrangement of substituents most favors the reaction?

Accepted Answer

Electron-withdrawing groups ortho and/or para to the leaving group.

Question 3

Given a benzene ring with both $$\mathrm{SO_3H}$$ and $$\mathrm{$$OCH_3$$}$$ substituents, which group will dominate the directing effect in an EAS reaction?

Accepted Answer

$$\mathrm{$$OCH_3$$} ($$ortho/para-directing, strong activator)

Question 4

A benzene ring has both $$\mathrm{NO_2$}$$ and $$\mathrm{NaO}$$ substituents. If bromination occurs, which position will bromine most likely add to?

Accepted Answer

Meta to $$\mathrm{NO_2$}$$

Question 5

Why do alkyl groups lose to resonance contributors in directing effects during EAS reactions?

Accepted Answer

Resonance contributors stabilize the intermediate more effectively than alkyl groups.

Question 6

Which of the following is the correct order of directing strength for EAS: $$\mathrm{NO_2$}$$, $$\mathrm{$$OCH_3$$}$$, alkyl?

Accepted Answer

$$\mathrm{$$OCH_3$$}$$ \u003e alkyl \u003e $$\mathrm{NO_2$}$$

Question 7

A benzene ring with $$\mathrm{$$OCH_3$$}$$ and $$\mathrm{NO_2$}$$ substituents undergoes bromination. Which group determines the major product's position?

Accepted Answer

$$\mathrm{$$OCH_3$$} ($$ortho/para-directing)

Question 8

Which mechanism best describes nucleophilic aromatic substitution on a ring with an electron-withdrawing group ortho to the leaving group?

Accepted Answer

Addition-elimination via a Meisenheimer complex.

Question 9

In an EAS reaction, what is the major product when a benzene ring has both a resonance donor and a resonance withdrawer?

Accepted Answer

The product directed by the resonance donor.

Question 10

Which of the following best describes the kinetic product in EAS reactions?

Accepted Answer

The product formed from the lowest energy transition state.

Question 11

A benzene ring with $$\mathrm{Br}$$ and $$\mathrm{$$OCH_3$$}$$ substituents undergoes nitration. Which position will the nitro group most likely add to?

Accepted Answer

Para to $$\mathrm{$$OCH_3$$}$$

Question 12

Which group is most likely to direct an incoming electrophile to the meta position on a benzene ring?

Accepted Answer

$$\mathrm{NO_2$}$$

Question 13

Why does the presence of electron-withdrawing groups ortho or para to the leaving group favor nucleophilic aromatic substitution?

Accepted Answer

They stabilize the negative charge in the intermediate via resonance.

Question 14

A benzene ring with $$\mathrm{CH_3$}$$ and $$\mathrm{NO_2$}$$ substituents undergoes acylation. Which group will dominate the directing effect?

Accepted Answer

$$\mathrm{NO_2$} ($$meta-directing, strong deactivator)

Question 15

Which of the following is NOT a plausible reason for the dominance of resonance donors over alkyl groups in EAS directing effects?

Accepted Answer

Alkyl groups are meta-directing.

Question 16

In a scenario where two substituents direct to different positions, which rule generally determines the major product?

Accepted Answer

The stronger activating group wins.

Question 17

Which of the following best describes the effect of a resonance withdrawer on EAS?

Accepted Answer

It directs incoming electrophiles to the meta position.

Question 18

A benzene ring with $$\mathrm{$$OCH_3$$}$$ and $$\mathrm{Br}$$ substituents undergoes Friedel-Crafts acylation. Which group will dominate the directing effect?

Accepted Answer

$$\mathrm{$$OCH_3$$} ($$ortho/para-directing, strong activator)

Question 19

Which of the following is a real-world application of nucleophilic aromatic substitution?

Accepted Answer

Synthesis of pharmaceuticals containing aryl amines.

Efficiency and Directing Effects in Electrophilic Aromatic Substitution (EAS)

Guida di studio - Domande di pratica

Study guide - Flashcard