Question

Select the statements below that are TRUE.

Select the statements below that are TRUE.

Answer 1

Concepts and reason

This reaction is based on the reactions of benzene and its derivatives. Benzene is an aromatic compound with three alternate single and double bonds. It has two resonating structures.

Benzene ring is an aromatic compound with delocalized pi electrons spread all over the ring. During addition reaction, benzene and its derivatives loses their aromaticity, hence they undergo substitution reactions in preference to addition reactions.

Fundamentals

Due to its aromatic nature, benzene does not undergo electrophilic addition reaction which are typical for alkenes. However it undergoes the electrophilic aromatic substitution in which the electrophile replaces the hydrogen of the benzene ring. In substitution, the hydrogen is replaced by the electrophile, and there is no loss of aromaticity of benzene ring.

(1)

Benzene is an aromatic compound. If electrophiles are added to the double bond, the aromaticity is lost.

Thus, the given statement is not true.

(2)

Benzene has delocalized pi electrons all over the ring. This attracts the electrophiles towards it. Thus electrophiles are substituted on the benzene ring replacing the hydrogen atom. This does not disrupt the aromaticity of the benzene ring.

Thus, the given statement is true.

(3)

The first step of substitution reaction is highly endothermic and have high energy of activation.

Thus, the given statement is not true.

(4)

Benzene is an aromatic compound and is much more stable than dienes and alkenes.

Thus, the given statement is not true.

(5)

When a substituent is added, the conjugated pi bond system breaks in the ring. Thus, the aromaticity of benzene ring is destroyed.

The given statement is true.

(6)

In substitution reaction of benzene, the electrophile interacts with the benzene to form an intermediate cation. The cation is not aromatic .In the next step, the proton is lost, and the aromaticity of benzene is regenerated.

Thus, the given statement is true.

Ans: Part 1

The statement is not true.