OXIDATION OF PROPENOIDIC PHENOLS CATALYZED BY N,N'-ETHYLENEBIS(SALICYLIDENEIMINATO)COBALT(II) [COSALEN] - REACTIVITY AND SPECTROSCOPIC STUDIES

Three propenoidic phenols, E-methyl ferulate, E-4-hydroxycinnamic acid methyl ester and E-3-chloro-4-hydroxycinnamic acid methyl ester, were oxidized with dioxygen, in the presence of N,N'-ethylenebis(salicylid eneiminato)cobalt(II) [Cosalen]. The yields of conversion to oxidized products depended on the reaction solvent and on the substituents on t he phenyl ring. EPR and electronic investigations suggest that an orga nometallic radical acts as the intermediate active species.