Electron spin resonance studies. Part X. An investigation of some aliphatic semidione and protonated semidione radicals

Abstract

Semidione radicals or their protonated derivatives, depending on the pH, are formed by the one-electron reduction of α-diketones by certain organic radicals and by the one-electron oxidation of the related acyloins by the hydroxyl radical. The mechanism of the reduction and the conformations of the radicals are discussed. The e.s.r. spectra observed during the reduction of biacetyl show pH-dependent alternating line-widths which are interpreted in terms of acid-catalysed interconversion of the tautomeric protonated trans semidiones.