Entropy–Energy Balance in Base Catalyzed Keto-Enol Interconversion: A Joint Theoretical and Experimental Investigation

The mechanism of base catalyzed keto-enol interconversion of aqueous 2-phenylacetylthiophene has been investigated by a joint application of experimental and computational approaches. Primarily we have focused our attention on the water-enolate proton transfer representing the rate determining step of the reaction. Computational results, in good agreement with experimental data demonstrate the crucial role exerted by the solvent. In particular, beyond the bulk catalytic effect an explicit assistance of solvent molecules allows the reaction to increase its efficiency. A combination on Molecular Dynamics simulations and Perturbed Matrix Method calculations also highlight the subtle balance between energetic and entropic effects which characterize the mechanistic scenario.