Riccardo Bini

A rationalization of the solvent effect on the Diels–Alder reaction in ionic liquids using multiparameter linear solvation energy relationships

The Diels-Alder reaction between cyclopentadiene and three dienophiles (acrolein, methyl acrylate and acrylonitrile) having different hydrogen bond acceptor abilities has been carried out in several ionic liquids and molecular solvents in order to obtain information about the factors affecting reactivity and selectivity. The solvent effects on these reactions are examined using multiparameter linear solvation energy relationships. The collected data provide evidence that the solvent effects are a function of both the solvent and the solute. For a solvent effect to be seen, the solute must have a complimentary character; selectivities and rates are determined by the solvent hydrogen bond donation ability (alpha) in the reactions of acrolein and methyl acrylate, but not of acrylonitrile.

Effect of ionic liquids on the Menschutkin reaction: an experimental and theoretical study.

The effect of ionic liquids (ILs) on the Menschutkin reaction between N-methylimidazole and benzyl halides has been investigated. Hammett correlations have been used to obtain information on the reaction mechanism of benzyl chlorides in ionic and molecular solvents. The solvent effects on this reaction have been examined using both multiparameter linear solvation energy relationships and theoretical calculations. These latter have been performed using a supermolecular approach, i.e., the IL is represented by an explicit ionic pair, IP. Two possible different reaction pathways have been obtained changing the position of the IL-IP with respect to the reagents. It is hypothesized that inside the IL the Menschutkin reaction of benzyl chloride with N-methylimidazole can follow different reaction pathways by considering the influence of dynamic heterogeneity in ionic media on the time scale of the lifetime of a transition state.