Explain the addition and substitution reaction with the help of examples. `C_2H_6` undergoes substitution reaction but not addition reaction. Why?

Explanation

• addition reaction in presence of catalyst to give saturated hydrocarbons.
Example: Hydrogenation of vegetable oil.

• Substitution reaction: In the presence of sunlight other group of atoms can replace hydrogen atoms one by one from carbon compounds.
Example: In the presence of sunlight, Chlorine replaces hydrogen atoms one by one from methane.
`CH_4 + Cl_2 overset("Sunugnt")(rarr) CH_3 CI + HCI`
• `C_2H_6` does not undergo substitution reaction because it is saturated hydrocarbon. In `C_2H_6` there will be single bond between carbon atoms. This is not an unsaturated compound. No hydrogen atoms can be added but hydrogen atoms can be substituted.