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Question
Which compound in the following pair will react faster in SN2 reaction with OH−?
CH3Br or CH3I
Solution
In the SN2 mechanism, the reactivity of halides for the same alkyl group increases in the order. This happens because as the size increases, the halide ion becomes a better leaving group.
R−F << R−Cl < R−Br < R−I
Therefore, CH3I will react faster than CH3Br in SN2 reactions with OH−.
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