Chapter 2 - Evidence for Organic Reaction Mechanisms

Abstract

This chapter addresses experimental and theoretical tools used to gather evidence to support or disprove a reaction mechanism. We therefore start by discussing what physical organic chemistry is using the framework of energetics and the concept of an energy reaction coordinate diagram. In this section, we also explain the difference between kinetic and thermodynamic control in terms of the shape of the energy reaction coordinate diagram. In the second section, we provide an outline of experimental techniques available to researchers interested in studying reaction mechanisms. These techniques are distinguished by whether they provide direct or indirect evidence for or against a particular mechanism. Classic literature examples are chosen to highlight the importance of each technique. Finally, the section concludes with an overview of the 300 problems analyzed in this book wherein we highlight which problems had certain experimental and/or theoretical evidence to support the original authors’ conclusions. The final section of this chapter revisits the Baeyer-Villiger oxidation introduced in Chapter 1 and provides an in-depth mechanistic analysis accounting for all available evidence. Based on this analysis, the mechanism with the strongest evidence and least number of contradictions or other logical issues is selected as the predicted operating mechanism for the Baeyer-Villiger oxidation.