Electrophilic Aromatic Substitution

What is the main reason aromatic systems prefer substitution over addition reactions?

• Aromatic systems are less stable than aliphatic systems.

• Aromatic systems have no pi bonds.

• Aromatic systems aim to maintain their stability.

• Aromatic systems do not interact with electrophiles.

In electrophilic aromatic substitution, what is the intermediate formed after the electrophile attaches to the benzene ring?

• Carbanion

• Radical ion

• Arenium ion

• Carbocation

How is aromaticity restored in the benzene ring during electrophilic aromatic substitution?

• By removing all pi bonds.

• By adding a halide ion.

• By adding a new electrophile.

• By forming a new pi bond after proton extraction.

Which of the following is NOT a characteristic of the arenium ion intermediate?

• It has delocalized positive charge.

• It is sp3 hybridized.

• It is a stable intermediate.

• It has high electron density.

Why is the first step of electrophilic aromatic substitution considered the rate-determining step?

• It involves the formation of a stable intermediate.

• It is an exothermic process.

• It involves breaking aromaticity, which is energetically unfavorable.

• It is the fastest step in the reaction.

What is the role of a Lewis acid catalyst in halogenation of benzene?

• To provide additional electrons.

• To consume the reactants.

• To increase the temperature of the reaction.

• To lower the activation energy of the reaction.

What is the main reason benzene does not react directly with bromine without a catalyst?

• Bromine is not reactive enough.

• Breaking aromaticity is too energetically unfavorable.

• Benzene lacks pi bonds.

• Benzene is too reactive.

In the halogenation of benzene, what is the function of the catalytic complex formed with iron tribromide?

• It prevents the reaction from occurring.

• It increases the energy of the reaction.

• It neutralizes the bromine atom.

• It stabilizes the benzene ring.

What happens to the bromine atom in the catalytic complex during the halogenation of benzene?

• It gains a formal negative charge.

• It loses its lone pairs.

• It becomes a radical.

• It gains a formal positive charge.

What is the byproduct formed during the bromination of benzene?

• HCl

• HBr

• H2O

• Br2