Question

Benzene reacts with chlorine in presence of light to yield:

• A. chlorobenzene
• B. trichlorobenzene
• C. tetrachlorobenzene
• D. benzenehexachloride

Answer 1

Answer: (D)

benzenehexachloride

In the presence of ultraviolet light (but without a catalyst present), hot benzene will also undergo an addition reaction with chlorine or bromine. The ring delocalisation is permanently broken and a chlorine or bromine atom adds on to each carbon atom.

For example, if you bubble chlorine gas through hot benzene exposed to UV light for an hour, you get $1,2,3,4,5,6$-hexachlorocyclohexane or benzenehexachloride.