The effect of electron-pair donor solvents on methylene reactivity

The effect of electron pair donor solvents on methylene reactivity has been theoretically studied by means of abinitio methods, using the split valence 3-21G basis set. The calculations have been done on the well-known methylene addition to ethylene, taking one water molecule in order to represent the donor solvent. We have shown that the process takes place via the formation of a reversible complex between water and methylene, the formation of this complex permitting to explain the experimentally observed decrease of methylene's electrophilicity. The analysis of the variation of the electronic charge density and of the solvation parameters along the reaction coordinate have also allowed to interpret the reaction in terms of the transfer of an electrophile (methylene) from a nucleophile (water) to another nucleophile (ethylene).