Direct iodination of alkanes using and UV light is practically ineffective under standard laboratory conditions. Which of the following precisely explains the thermodynamic hurdle of this reaction and

Question

Direct iodination of alkanes using $I_2$ and UV light is practically ineffective under standard laboratory conditions. Which of the following precisely explains the thermodynamic hurdle of this reaction and the necessary modification required to drive it forward?

Prashant Kotian · Accepted Answer

Correct answer: B. In free-radical halogenation, the thermodynamic feasibility depends on the propagation steps. For iodination, the abstraction of a hydrogen atom by the iodine radical is strongly endothermic ( kcal/mol), making the overall reaction highly reversible and slow. Consequently, the backward reaction (reduction of alkyl iodide by ) dominates. To force the reaction forward, must be removed from the system. This is achieved by adding a strong oxidizing agent like or , which oxidizes back to ().

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