Question

What is the role of Benzoyl peroxide in addition to polymerisation of alkenes? Explain its mode of action with the help of an example.

Answer 1

Hint: Benzoyl peroxide is a chemical with the molecular formula as $${({C_6}{H_5} - C\left( { = O} \right)O - )_2}$$ . In the structure of benzoyl peroxide, we can say that two benzoyl groups are connected with a peroxide $( - O - O - )$ bond. Polymerisation of alkenes consists of three steps which we will discuss in detail and benzoyl peroxide plays its role as a chain reaction initiator in this polymerisation reaction.

Complete answer:
We know that addition polymerisation is a process of formation of a polymer in which no small compound or molecule is released. This process is a chain reaction in which there are three steps such as: chain initiation, chain propagation and chain termination.
Benzoyl peroxide is a chemical with the molecular formula as $${({C_6}{H_5} - C\left( { = O} \right)O - )_2}$$ . In the structure of benzoyl peroxide, we can say that two benzoyl groups are connected with a peroxide $( - O - O - )$ bond.
So, benzoyl peroxide plays an important role in addition to the polymerisation reaction and acts as a chain initiator to start the polymerisation reaction. Therefore it plays a role in the first step of the reaction.
Now, we will take the example of ethane and in addition polymerisation of ethane, we get a polymer known as polythene.
First step is chain initiation which is done by benzoyl peroxide as follow:

Therefore, as we can see in the above reaction, benzoyl peroxide initiates the polymerisation reaction by generating free radicals. So, it acts as a chain initiator.

Note:
Other than a chain initiator, benzoyl peroxide is a powerful bleaching agent. It can also be used to treat acne. Despite these applications and importance, its concentrated version is potentially explosive. It has carcinogenic potential and has some side effects too. It can cause skin irritation and it is toxic in nature.