The heterolytic cleavage of the bond is the rate-determining step in reactions. Which parameter fund — Haloalkanes and Haloarenes Chemistry Question

💡 Solution & Explanation

Although the $C-F$ bond is the most polar due to the high electronegativity of fluorine, alkyl fluorides are the least reactive towards nucleophilic substitution. This is because the reaction rate is ultimately governed by the activation energy required to break the $C-X$ bond. The bond dissociation enthalpy sharply decreases down the halogen group ($C-F > C-Cl > C-Br > C-I$) due to increasing atomic size and poor orbital overlap. Thus, the weakest bond ($C-I$) breaks most easily, making iodides the most reactive.