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Question
What is the role of benzoyl peroxide in addition polymerisation of alkenes? Explain its mode of action with the help of an example.
Solution
Role of benzoyl peroxide is to generate free radicals. A variety of alkenes or dienes and their derivatives are polymerised in the presence of a free radical generating initiator (catalyst) like benzoyl peroxide, acetyl peroxide, tert-butyl peroxide, etc. For example, the polymerisation of ethene to polythene consists of heating or exposing to light a mixture of ethane with a small amount of benzoyl peroxide initiator. The process starts with the addition of phenyl free radical formed by the peroxide to the ethane double bond thus generating a new and larger free radical. This step is called chain initiating step.
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