Question

What is the substitution reaction? Write the reaction of chlorine with methane?

Answer 1

Substitution reaction or single displacement reaction is a chemical reaction in which one functional group of a chemical compound is replaced by another functional group.

Complete step by step answer:
In this question we have asked about the substitution reaction. As we already mentioned that in substitution reaction, one functional group of a chemical compound is replaced by another functional group.
During the substitution the bond between the ligand and the reactive center is broken, while a new bond is formed between that center and the new species.
There are 2 types of substitution reaction- Nucleophilic substitution reaction and electrophilic substitution reaction.
Nucleophilic substitution is a reaction in which a leaving group is replaced by an electron rich compound. It occurs in two ways: SN1 and SN2.
SN1 reactions are unimolecular in rate of reaction and have a stepwise mechanism, while Sn2 reactions are bimolecular in rate of reaction and have a concerted mechanism.
Electrophilic substitution reactions are reactions in which an electrophile displaces a functional group in a compound, generally, a hydrogen atom.
Electrophilic substitution are of two types: aromatic electrophilic substitution and nucleophilic substitution reaction.
We have also asked to write a chemical reaction of chlorine with methane. The reaction of chlorine with methane occurs in three steps. 1. Initiation, 2. Propagation and 3. Termination.
$C{H_4} + C{l_2} \to {\text{ }}C{H_3}Cl$ (Chloromethane)
$C{H_3}Cl + C{l_2} \to {\text{ }}C{H_2}C{l_2}$ (Dichloromethane)
$C{H_2}C{l_2} + C{l_2} \to {\text{ }}CHC{l_3}$ (Trichloromethane)
$CHC{l_3} + C{l_2} \to {\text{ }}CC{l_4}$ (Tetrachloromethane)

Note:
Chlorination of methane is a chain process. It is initiated by UV radiation or sunlight. UV radiation breaks Cl2 into Cl and Cl free radicals. A chlorine atom has an unpaired electron so it acts as a radical and proceeds the reaction with a free radical mechanism.