Solvent as Catalyst: Computational Studies of Organic Reactions in Solution

Quantum and statistical mechanics are being used to study the origin of solvent effects on the rates of organic reactions. Typically, a reaction path is obtained from ab initio molecular orbital calculations in the gas phase. The effects of solvation are then determined for this pathway with free-energy perturbation calculations using Monte Carlo simulations in several solvents. The latter calculations feature a classical description of the intermolecular interactions with partial charges for the reacting system determined from the quantum mechanical wavefunctions. Application to a variety of reactions including substitutions, additions, and pericyclic reactions has revealed insightful details on variations in solvation along the reaction paths. Such information is valuable for the rational design of catalysts.