Question

Propose a mechanism for the following reaction:

Short answer

The answer is,

Mechanism

Step-by-step solution

Electrophilic addition

The electrophilic addition of the aromatic system involves the formation of a new sigma bond by the breaking of a pi bond in it. The electrophiles are the electron-deficient species. The double bonds in the benzene ring undergo addition to the electrophiles forming the cation system, which will regain aromaticity by removing protons.

Explanation

The mechanism for the given reaction is shown below.

Mechanism

The mechanism involves the electrophilic addition to the benzene ring. The benzene protons are then removed to regain the aromaticity of the ring. This is repeated until all the hydrohen is replaced with the Deuterium atom.