Question

Explain the free radical substitution of alkane?

Answer 1

Alkanes are a group of chemicals that have single covalent connections between carbon and hydrogen atoms. This category of chemicals is made up of solitary covalent connections between carbon and hydrogen atoms. A similar series with the chemical formula ${{C}_{n}}{{H}_{2n+2}}$ is also included.
Alkanes are the most basic class of compounds. They are made up entirely of carbon and hydrogen. Each carbon atom has four bonds, whereas each hydrogen atom has one.

Complete answer:
Atoms or groups of atoms with a single unpaired electron are known as free radicals. These radicals are involved in a free radical substitution reaction. When a bond fractures equally, each atom receives one of the two electrons, resulting in the formation of free radicals. Homolytic fission is the name given to this process. The symbol is written with a dot added to represent the unpaired electron to denote that a species (either an atom or a collection of atoms) is a free radical.
Because free radicals are extremely reactive, they may be used to convert alkanes to halogenoalkanes. This may be broken down into three simple steps: Propagation, Initiation, and Termination
Let's look at a reaction that can happen in the environment between chlorine and methane ($CH_4$).
Initiation.
$C{{l}_{2}}\to 2C{{l}^{.}}$
UV radiation breaks down a chlorine molecule, causing homolytic fission (electrons from the disrupted covalent link travel to each of the two atoms, resulting in free radicals- a species with an unpaired electron= reactive).
Propagation.
These free radicals will then react with other molecules in the environment, such as methane.
$C{{l}^{.}}+C{{H}_{4}}\to HCl+C{{H}_{3}}^{.}$
The free radical donates its lone electron to create a new covalent connection with Hydrogen, splitting the C-H bond in Methane and forming a new radical (a methyl radical) that will continue to react.
$C{{H}_{3}}^{.}+C{{l}_{2}}\to C{{H}_{3}}Cl+C{{l}^{.}}$
Chloromethane, a halogenalkane, can be formed in this process.
Termination.
When two radicals react together, a new molecule is formed that will not react further. This can also be used to create the desired item.
$C{{H}_{3}}^{.}+C{{l}^{.}}\to C{{H}_{3}}Cl$
Chloromethane was also created.
In this example, create a new alkane:
$C{{H}_{3}}^{.}+C{{H}_{3}}^{.}\to {{C}_{2}}{{H}_{6}}$
Which is the source of ethane

Note:
Homolysis produces a free radical in the initial stage, known as initiation. Heat and UV light can cause homolysis, but radical initiators such organic peroxides and azo chemicals can also cause it. UV light is used to split one diatomic species into two free radicals. Termination is the ultimate phase, which involves the radical recombining with another radical species. The stages where additional radicals are generated and subsequently react are collectively termed as propagation if the reaction is not halted and the radical group(s) continue to react. This is due to the creation of a new radical capable of participating in secondary reactions.