Which of the following statements are TRUE regarding the free radical addition of hydrogen halides t — Reaction Mechanism Chemistry Question

💡 Solution & Explanation

The peroxide effect is unique to $HBr$ because both steps of its propagation chain are exothermic. For $HCl$, the abstraction of H from the strong $H-Cl$ bond by the carbon radical is highly endothermic. For $HI$, the initial attack of the large $I^\cdot$ radical on the alkene is endothermic, and the $I^\cdot$ radicals readily dimerize to $I_2$. Free radical addition does not involve a cyclic halonium ion (which is characteristic of electrophilic addition).