Why is SN2 mechanism chosen rather than SN1 in the preparation of primary alkyl halides?
In the preparation of primary alkyl halides, you usually create something more labile toward nucleophilic substitution than the halide itself. SN1 is not a possible reaction pathway for the synthesis of a primary alkyl halide because primary carbocations are incredibly unstable … they aren’t formed. SN2 mechanisms proceed without an intermediate carbocation, which makes SN2 the predominant mechanism.
