Question

Write a balanced chemical equation for the substitution reaction of Cl2 with benzene to make para-dichlorobenzene in the presence of FeCl3 as a catalyst.

Answer 1

Balanced equation for the formation of para-dichlorobenzene from benzene in presence of catalytic FeCl3 and Cl2 can be shown as follows:

It is a two step reaction. In first step one molecule of Cl2 reacts with benzene to form chlorobenzene and HCl molecule. FeCl3 acts as catalysts by incresing reactivity of Cl2. In second step chlorobenzene further undergoes chlorination at para position by reacting with another molecule of Cl2 to give para-dichlorobenzene and forming one more molecule of HCl.