ON RADICAL-ANIONS IN ELUCIDATION OF MECHANISMS OF ORGANIC-REACTIONS

Radical anions have been used to investigate the role of electron tran sfer in nucleophilic reactions and to obtain reduction potentials of s hort-lived radicals. In the first type of investigation the radical an ions have been used to establish the dependence of the rate of electro n transfer from an outer-sphere electron donor to a given substrate, t o establish the stereochemistry of a radical coupling with the substra te, and to find the entropy and enthalpy of activation of electron tra nsfer reactions compared with polar reactions. The potentials of short -lived radicals have been obtained from the competition between coupli ng of a radical with a radical anion and the reduction of the radical by the radical anion. The potentials have been used to rationalize som e reactions such as the occurrence of radicals in certain Grignard rea ctions and the photochemical pinacolization of benzophenone in 2-propa nol.