Question

Which of the following are used as free radical chain initiators?
THIS QUESTION HAS MULTIPLE CORRECT OPTIONS
A.Benzoyl peroxide
B.di-tert butyl peroxide
C.carbon tetrachloride
D.Benzoquinone

Answer 1

We know that a radical initiator is a species that acts as the reactant of the initiation step of reaction. But it is not a part of the propagation steps of the reaction. They are used in chain growth polymerization reactions.

Complete step by step answer:
Let’s understand the polymerization reaction in detail. The formation of polymers on combining a large number of monomers is termed as polymerization reaction.
The two classification of polymerization reactions are addition or chain growth polymerization and condensation or step growth polymerisation.
Let’s discuss the additional polymerization in detail. In this type of polymerization reaction, joining of two same or different monomers takes place in large scale to form polymers. The monomers are generally alkadiene, alkene and their derivatives. This polymerization results in the increase of chain length or we can say that chain growth occurs through the formation of ionic species or free radicals. However, the most common method of this type of polymerization takes place using free radicals.
Now we understand the free radical mechanism. In this method, a variety of dienes or alkenes are polymerized in presence of a free radical generating initiator which acts as catalyst namely, acetyl peroxide, benzoyl peroxide, tert-butyl peroxide etc. These radicals take part in the initial step of the reaction.
So, both Benzoyl peroxide and di-tert butyl peroxide are used as free radical chain initiators.
Hence, the correct choices are A and B.

Note:
Radical initiators are the chemical species that are capable of producing radical species under mild conditions and promote radical reaction. They consist of weak bonds of small bond dissociation energy.