Effect of solvation on reaction rate
Generally speaking. Both the substrate and the product form a solvate more or less in solution. When these solvates form an unstable intermediate compound with any of the reaction molecules to lower the activation energy, the reaction rate can be increased. If the solvent molecule forms a relatively stable compound with the substrate, it is generally possible to increase the activation energy and slow down the reaction rate. If the energy after solvation of the activated complex is reduced, thereby reducing the activation energy, the reaction rate is increased.