Double Bond Migration Mechanism in Allyl Systems Involving the Hydroxide Ion. 2. Polarizable Continuum Model (PCM)

Isomerization processes of a double bond site in propene and methylthiopropene molecules with the hydroxide ion were studied in the framework of the RHF/6-31+G*, MP2/6-31+G*, and B3LYP/6-31+G* (density functional) ab initio methods. The solvent effect was taken into account using PCM in its IEFPCM and SCIPCM versions. It is shown that to construct a reaction profile for propene rearrangement, it suffices to perform geometry optimization of stationary points within the Born–Onsager model with further refinement of the energy using IEFPCM. The reaction profiles obtained display that the multiple bond migration mechanism involving the hydroxide ion proton is energetically preferable to the two-stage mechanism forming a solvated carbanion for the propene molecule and for the methylthiopropene molecule that forms a much more stable carbanion.