In the presence of peroxide, HCl and HI do not give anti-Markownikoff's addition of alkenes because:
In the presence of peroxide, HCl and HI do not give anti-Markownikoff's addition of alkenes because:
One of the steps is endothermic in $\mathrm{HCl}$ and HI
Both HCl and HI are strong acids
$\mathrm{HCl}$ is oxidizing and the $\mathrm{HI}$ is reducing
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 HCl, first step is exothermic, and second step is endothermic and in HI, no step is exothermic. Hence HCl and HI do not undergo antiMarkownikoff's addition.