In the presence of peroxide, $\mathrm{HCl}$ and $\mathrm{HI}$ do not give anti-Markownikoff's addition of…

In the presence of peroxide, $\mathrm{HCl}$ and $\mathrm{HI}$ do not give anti-Markownikoff's addition of alkenes because:
  1. One of the steps is endothermic in $\mathrm{HCl}$ and $\mathrm{HI}$
  2. Both $\mathrm{HCl}$ and $\mathrm{HI}$ are strong acids
  3. $\mathrm{HCl}$ is oxidizing and the $\mathrm{HI}$ is reducing
  4. All the steps are exothermic is $\mathrm{HCl}$ and $\mathrm{HI}$

Solution

Anti-Markownikoff addition is possible only in case of $\mathrm{HBr}$ and not in $\mathrm{HCl}$ and $\mathrm{HI}$. In $\mathrm{HBr}$ both the chain initiation and propagation steps are exothermic, while in $\mathrm{HCl}$, first step is exothermic, and second step is endothermic and in HI, no step is exothermic. Hence $\mathrm{HCl}$ and $\mathrm{HI}$ do not undergo anti-Markownikoff's addition.

Asked in: JEE Main 2014 (12 Apr Online)

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