Reactions of radical anions. Part 3.—Disproportionation of benzil radical anion

Abstract

The disproportionation reaction of the benzil radical anion in tetrahydrofuran has been examined by electron spin resonance spectroscopy. The following equilibrium has been studied: [graphic omitted] The radical anion concentration, the total dianion concentration (cis + trans) and the neutral benzil concentration has been determined and the equilibrium constant, K₁=[dianion(cis+ trans)][benzil]/[radical anion]² measured at different temperatures for the gegen ions Li⁺, Na⁺, K⁺, and Cs⁺. As the gegen ion changes from Li⁺ to Cs⁺ the equilibrium constant K₁ increases. Evidence for ion-pair formation is found from the metal splitting in the e.s.r. spectrum.