11 Reaction mechanisms
Part (i) Radical and radical ion reactions
Abstract
This chapter provides an overview of the 2004 literature pertaining to the mechanism and kinetics of reactions involving neutral radicals and radical ions in solution. This overview begins by highlighting significant contributions to our understanding of fundamental classes of reactions: substitution, addition, and fragmentation. Afterwards, rearrangement reactions, which are intramolecular variants of these fundamental classes, are examined. With regard to a specific subclass of substitution reactions, Evans and Polanyi provided a foundation for understanding structure–reactivity relationships in hydrogen atom abstraction processes in 1938. Hence, it is particularly noteworthy that in 2004, a great deal of research effort was still directed towards improving our understanding of this fundamental class of radical reactions. There are many reasons for this continued interest: radical reactions are important in biological systems, and a number of fundamental processes (e.g., enzyme-catalyzed oxidations,