Question

What are the products when ethane reacts with chlorine in the presence of sunlight?

Answer 1

Ethane will undergo substitution reaction. Usually one hydrogen atom will be replaced by one chlorine atom. (I use the word usually since more than one atom can be replaced, but less likely.) However, this reaction needs light, and it will not occur in the dark. First, Cl-Cl bond will be broken symmetrically. Each chlorine atom will get one electron from two former bonding electron. Species like this one (with single unpaired electron) are called radicals. Formation of radicals in this step is called initiation, and light is needed in this step. Then chlorine radical will abstract one hydrogen atom from ethane along with one electron from C-H bond, leaving ethyl radical. This step is called propagation, generation of new radicals from old radicals. Finally, chlorine radical and ethyl radical will couple will each other to form chloroethane. This last step is known as termination. Two major compounds are formed, chloroethane and hydrogen chloride (during propagation). C2H6 + Cl2 → C2H5Cl + HCl (ethane) (chloroethane) C2H5Cl + Cl2 → C2H4Cl2 + HCl (chloroethane) (dichloroethane) C2H4Cl2 + Cl2 → C2H3Cl3 + HCl (dichloroethane) (trichloroethane) C2H3Cl3 + Cl2 → C2H2Cl4 + HCl (trichloroethane) (tetrachloroethane) C2H2Cl4 + Cl2 → C2HCl5 + HCl (tetrachloroethane) (pentachloroethane) C2HCl5 + Cl2 → C2Cl6 + HCl (pentachloroethane) (hexachloroethane)