Radical Chain Reactions in Foundational Organic Chemistry

In the foundational organic chemistry course radical chain reactions are introduced via the chlorination of alkanes. The mechanism of a chain reaction and its selectivity based on the homolytic C-H bond dissociation energies leading to methyl, primary, secondary, tertiary, allylic, and benzylic alkyl radicals are vital to understanding of material covered later in the course. Radical chain polymerization introduces polystyrene and poly(vinyl chloride) which, due to their everyday use, are more interesting to students than chloroalkanes. The polymerizations further support the importance of radical chain reactions, and the head-to-tail structures of the polymers reinforce the importance of selectivity of radical formation. Radical chain autoxidation of ethers and lipids and inhibition of both polymerization and autoxidation of foods by hindered phenols complete the discussion of radical reactions. The additional time devoted to polymerization and autoxidation is compensated by omitting topics such as radical addition of HBr to alkenes and multistep syntheses.