Cycloaddition reactions electrochemical studies

A number of alkene radical cations have been generated in matrices at low temperature and have also been studied by ESR, CIDNP, and electrochemical methods. However, until recently very little absolute kinetic data have been available for the reactions of these important reactive intermediates in solution under conditions comparable to those used in mechanistic or synthetic studies. In a few cases, competitive kinetic techniques have been used to estimate rates for nucleophilic additions or radical cation/alkene cycloaddition reactions. In addition, pulse radiolysis has been used to provide rate constants for some of the radical cation chemistry relevant to the pho-topolymerization of styrenes. More recently, wc and others have used laser flash photolysis to generate and characterize a variety of alkene radical cations. This method has been extensively applied to the study of other reactive intermediates such as radicals, carbenes, and carbenium ions and is particularly well-suited for kinetic measurements of species that have lifetimes in the tens of nanoseconds range and up and that have at least moderate extinction coeffleients in the UV-visible region. 

Addition reactions, electron transfer reactions, and reactions involving the opening of the fullerene cage (chemical surgery) have been thoroughly studied on fullerenes. Other reactions such as nucleophilic additions, cycloaddition reactions, free-radical additions, halogenations, hydroxylation, redox reactions, and metal transition complexations have been reported for Cgo as well. Furthermore, fullerenes are easily reduced by electron-rich chemical reagents as well as electrochemically. Their oxidation, however, is considerably more difficult to achieve [17]. Thus, electrochemical measurements showed the formation from the monoanion to the hexaanion [18]. 

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