Why chlorination of methane is not possible in dark?
Answer»
Chlorination of methane is a free radical substitution reaction.
Before chlorine reacts with methane, the Cl-Cl single bond must break to form free radicals and this can only be done in the presence of ultraviolet light.
In dark, chlorine free radicals formation is not possible and so chlorination of methane is not possible in dark.
The ultraviolet light is a source of energy and it being used to break of Cl-Cl and produce Cl free radical Free radical’s which can attack methane. in dark this is not possible.