Briefly explain the origin of this rule from a mechanistic perspective. Electrophilic addition of HX occurs to give the most stable carbocation intermediate. Give an equation which clearly illustrates antiMarkovnikov addition. Write the E1 mechanism for this reaction. Briefly explain your choice of mechanism for this reaction.
Acetate ion is a modest base, but iodide is an excellent leaving group.
Therefore, the reaction could occur by the E2 mechanism. These requirements are met, so the reaction could occur by the E1 mechanism. Given a choice, we predict the reaction will occur by the E2 mechanism because this avoids the energetically-expensive step of carbocation formation. However, E2 is slowed in this case because acetate is a modest base. Thus, the reaction might occur by either mechanism.