Potential tuning and reaction control in the Diels–Alder reaction between cyclopentadiene and methyl acrylate in supercritical carbon dioxide

Abstract

The ratio of endo- to exo-products in the Diels–Alder reaction between cyclopentadiene and methyl acrylate in supercritical carbon dioxide, plotted vs. the density of the medium, was found to go through a maximum at a density higher than the critical density. The effect can be explained in terms of the adjustment of the position of the nearest-neighbour solvent molecules with respect to the transition state. A theoretical discussion is given, which justifies this process being described as ‘potential tuning’.