Question 1

Which step is the rate-determining step in the electrophilic aromatic substitution (EAS) mechanism, as shown in the reaction coordinate diagram?

Accepted Answer

Step 1: Formation of the arenium ion (sigma complex)

Question 2

Which of the following substituents is an ortho/para-directing activating group on a benzene ring?

Accepted Answer

$$-$$OCH_3$$

Question 3

Why do halogens, despite being deactivating, direct electrophilic aromatic substitution to the ortho and para positions?

Accepted Answer

They are electron-donating by resonance, increasing electron density at ortho and para positions.

Question 4

Which product is the major product when m-xylene is nitrated with $$HNO_3$$ and $$H_2SO_4$$?

Accepted Answer

The nitro group enters the position para to one methyl and ortho to the other methyl group.

Question 5

Which of the following statements best explains why Friedel–Crafts acylation does not lead to polysubstitution, while Friedel–Crafts alkylation does?

Accepted Answer

The acyl group is electron-withdrawing and deactivates the ring toward further substitution.

Question 6

Which of the following is required for the iodination of benzene to proceed efficiently?

Accepted Answer

A strong oxidizing agent such as $$HNO_3$$

Question 7

A benzene ring with a $$-NO_2$ group and a $$-$$OCH_3$$ group is sulfonated with $$SO_3/H_2SO_4$. Where does the sulfonic acid group (-SO_3H$) most likely enter?

Accepted Answer

Ortho or para to $$-$$OCH_3$$

Question 8

Which of the following best describes the effect of an electron-withdrawing group (EWG) on the reactivity and regioselectivity of electrophilic aromatic substitution?

Accepted Answer

Decreases reactivity and directs substitution to the meta position

Question 9

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

Accepted Answer

Carbocation rearrangements can occur, leading to unexpected products.

Question 10

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

Accepted Answer

It reduces benzene to a non-conjugated 1,4-cyclohexadiene using sodium or lithium in liquid ammonia and alcohol.

Question 11

Which of the following best describes the mechanism of nucleophilic aromatic substitution (S$$_NAr$$)?

Accepted Answer

Addition of a nucleophile to the aromatic ring, followed by elimination of a leaving group

Question 12

Which of the following is true about the Suzuki coupling reaction?

Accepted Answer

It couples an aryl or vinyl halide with a boronic acid or boronate ester using a palladium catalyst.

Question 13

Which of the following is a key feature of the Heck reaction?

Accepted Answer

It forms substituted alkenes by coupling aryl or vinyl halides with alkenes using a palladium catalyst.

Question 14

Which of the following statements about the benzyne mechanism is correct?

Accepted Answer

It involves elimination of a leaving group and a hydrogen to form a highly reactive benzyne intermediate.

Question 15

Which of the following best explains why the ortho and para positions are more reactive toward electrophilic attack in the presence of an electron-donating group?

Accepted Answer

Resonance structures place negative charge density at the ortho and para positions, stabilizing the arenium ion.

Question 16

Which of the following is a correct statement about the effect of multiple substituents on a benzene ring during EAS?

Accepted Answer

The strongest activating group usually dictates the major directing effect.

Question 17

Which of the following is a property of Gilman reagents ($$R_2CuLi$$)?

Accepted Answer

They are less reactive than alkyl lithium reagents and are used for selective coupling reactions.

Question 18

Which of the following best describes the outcome when benzene is treated with excess chlorine under heat and pressure?

Accepted Answer

Multiple chlorines add to the ring after the first difficult addition.

Reactions of Aromatic Compounds: Electrophilic and Nucleophilic Substitution, Coupling, and Addition Mechanisms

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