The Kharasch (peroxide) effect causes the anti-Markovnikov addition of hydrogen halides to unsymmetr — Hydrocarbons Chemistry Question
Question
The Kharasch (peroxide) effect causes the anti-Markovnikov addition of hydrogen halides to unsymmetrical alkenes. Which hydrogen halide is the ONLY one to exhibit this effect?
Answer: A
💡 Solution & Explanation
The free-radical chain mechanism requires both propagation steps to be exothermic. For $HCl$, the H-abstraction step is endothermic. For $HI$, the radical addition step is endothermic. Only $HBr$ has two exothermic propagation steps.
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