QM/MM/MC Simulations for the Elucidation of Ionic Liquid Solvent Effects upon Organic Reactions

Abstract

The research in this dissertation is focused on elucidating and understanding ionic liquid solvent effects on classical organic reactions. Ionic liquids are an exciting class of solvents that have attracted the attention of a growing number of scientists as a reaction medium for an assortment of chemical reactions over the last ten years. The increase in interest is due in part to the classification of ionic liquids as “green”, but more so for their complex reaction environment. Ionic liquids are molten salts, therefore the microenvironment is completely different than that of molecular solvents. Ionic liquids are complex solvent systems capable of many types of intermolecular interactions. Proper description of the physico-chemical properties aspects of solute-solvent interactions is vital to understanding the solvent effects on chemical processes, and reaction rates. Three organic reactions were chosen to investigate the complex behavior of the ionic liquid environment: (1) the base catalyzed β-elimination, (2) the nucleophilic aromatic substitution reaction, and (3) a heterocyclic rearrangement reaction called the Boulton-Katrizky rearrangement. These specific reactions were chosen to elucidate the experimentally observed ionic liquid behavior, e.g., increased favorable electrostatic interactions, increased stabilization through π-π interactions, and an increase in hydrogen bond donor and acceptor capabilities. The empirical effects of ionic liquids on many organic systems have been reportedly, however a theoretical examination of the unique reaction environment and ionic liquid effects is still in its infancy. It is hoped the research iii in this dissertation will shed light on the microscopic details of how ionic liquids operate upon and affect chemical reactions.