Briefly explain your mechanism choice for the previous question. A nucleophilic substitution reaction of this nature will proceed by the S N 2 mechanism in preference to the S N 1 mechanism because the S N 2 mechanism avoids the energtically-expensive carbocation formation step. We consider S N 1 only when S N 2 has been ruled out, or if the conditions obviously favor S N 1. Amines are generally modest or good nucleophiles. Good leaving group .
Iodide ion is an excellent leaving group because it is highly polarizable.
Substitution not occurring at tertiary carbon . In this case, the substitution is occurring at a 1 o carbon. Therefore the reaction will most probably proceed via the S N 2 mechanism. Draw the transition state for the slowest step of this reaction. The S N 2 mechanism is a concerted, one-step mechanism, with only one transition state.