Question

Why is dark and cold conditions is preferred for chlorination of benzene when the chlorine is in excess quantities while usually the condition in which light is available is preferred? In have an assumption . light makes homolytic cleavage in which chlorine radical is resulted which is not preferred there and in dark condition the catalyst makes its work by breaking the chlorine bond by a heterolytic manner. Is my intuition correct? Or is there any other reason ?.

Answer 1

Yes the reason you have specified is correct. We do not prefer chlorine radicals in the chlorination of benzene hence absence of UV light is prefer i.e dark and cold condition