Free Radical Substitution
AQA A-Level Chemistry
3.3.2
Alkanes are generally unreactive because of the strong covalent bonds within their molecules, but under the right conditions they can react with halogens to form halogenoalkanes. Building on our understanding of alkanes and halogens, we can now explore how these reactions occur through a free-radical substitution mechanism. This provides an important foundation for understanding the structure, properties and reactions of halogenoalkanes later in the course.
In this topic you will:
- Understand what free radicals are and how they are formed through homolytic fission.
- Explain how alkanes react with halogens through a free-radical substitution mechanism.
- Understand the three stages of the mechanism — initiation, propagation and termination — and how to represent each using equations.
- Construct overall equations for the formation of halogenoalkanes, including further substitution.
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