Question

What is the first step in the general mechanism for electrophilic aromatic substitution? a. Protonation of the aromatic ring b. Deprotonation of the aromatic ring c. Addition of the electrophile to the aromatic ring d. Loss of the electrophile from the aromatic ring.

Answer 1

Answer:

c. Addition of the electrophile to the aromatic ring

Explanation:

The first step of the mechanism for electrophilic aromatic substitution is an addition, in which the electrophilic compound reacts with an electron pair of the aromatic system. This step generally needs to be catalyzed with a Lewis acid. This addition leads to the formation of a cyclohexadienyl carbocation. This carbocation is unstable, due to the presence of the load on the molecule and the loss of aromaticity. This is partly offset by the relocation of the positive resonance charge.

Answer 2

Answer:

c. Addition of the electrophile to the aromatic ring

Explanation:

The electrophilic aromatic substitution mechanism can be denoted as follows:

• The first step is the attack (addition) of the eletrophile to the aromatic ring, forming an aryl ring.

• The second step is the replacement of H by the electrophile (deprotonation), restoring the aromatic ring.