Electron spin resonance studies of reduction by solvated electrons in liquid ammonia. Part II. Pyridines

Abstract

The reductions of a series of ring-substituted pyridines by solvated electrons in liquid ammonia have been examined using the rapid-mixing e.s.r. cell described in Part I. In most cases a spectrum corresponding to the monomeric radical-anion is found but pyridine-2,5-, pyridine-2,6-, and pyridine-3,5-dicarboxylic acids produce spectra indicating the presence of an additional proton which is probably attached to the hetero-atom. Prior addition of an acid (ethanol) to the medium results in the conversion of C₅H₅N^–· to C₅H₅NH·. A series of complementary e.s.r. studies using a ‘static’ technique indicates that relatively rapid dimerisation of the monomer radical occurs to give (ultimately) the corresponding bipyridyl radical-anion. Simple Hückel and McLachlan calculations have been performed on all the radicals.