FORMATION AND DECAY OF FREE CATION-RADICALS IN THE COURSE OF ELECTROOXIDATION OF 1,2-DIHYDROPYRIDINES AND 1,4-DIHYDROPYRIDINES (HANTZSCH ESTERS)

The kinetic parameters and pathways of decay of the cation-radicals fo rmed as primary products in the course of electro-oxidation of the eat ers of 1,2- and l,4-dihydropyridine have been studied by rotating ring -disk electrode (rrde) method in temperature range from +20 degrees C to -30 degrees C. Two ways of the decay of these cation-radicals, ie v ia loss of H+ and via loss of H-. operating simultaneously have been p roved to be possible. Competition between these two ways depends on th e influence of temperature and on electronic effects of the substitute s attached to the dihydropyridine ring. Cation-radicals of 1,2-dihydro pyridine derivatives the sufficiently more stable than those of 1,4-di hydropyridines due to a more extended common pi-electron system of the latter. 1,2-Dihydropyridine derivatives are oxidized more readly (by 200-250 mV) than the corresponding 1,4-dihydropyridines.