BDE,pKa(HA+), BDE(HA-) and DGH-(A.) for para-substituted acetophenone semicarbazones 4-RC6H4C(:NNHCONH2)Me were estimated from thermodn. cycles by combining their equilibrium acidities [pKa(HA)] with the appropriate electrode potential data [Eox(HA),Erd(HA) and Eox(A-)]. The results were discussed in terms of the substituent effects.

Key words: SUBSTITUENT EFFECT, SEMICARBAZONE P, OXIDATION-REDUCTION POTENTIAL, FREE RADICALS, DISSOCIATION CONSTANT, THERMODYNAMIC STABILITY, ION-RADICAL (=RADICAL ION)