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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.
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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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