BIOMIMETIC OXIDATION OF INDOLE-3-ACETIC-ACID AND RELATED SUBSTRATES WITH HYDROGEN-PEROXIDE CATALYZED BY 5,10,15,20-TETRAKIS '-DICHLORO-3'-SULFONATOPHENYL)PORPHYRINATOIRON(II) HYDRATE IN AQUEOUS-SOLUTION AND AOT REVERSE MICELLES

The reaction of indole-3-acetic acid (IAA) with hydrogen peroxide cata lysed by ro-3'-sulfonatophenyl)porphyrinatoiron(III)hydrate [Cl8TPPS4F e(III)(OH2)(2)] gives indole-3-carbinol (IC) and indole-3-carboxaldehy de (IA) in aqueous buffer solution. The oxidation of IAA with H2O2 in the presence of Cl8TPPS4Fe(III)(OH2)(2) in AOT reverse micelles gives higher yields of IA than in aqueous solution at the same pH. The yield s of different oxidation products in AOT reverse micelles depend on th e pH, the water to surfactant ratio (We) and concentration of Cl8TPPS4 Fe(III)(OH2)(2) in AOT reverse micelles. The oxidation of IC with H2O2 in the presence of Cl8TPPS4Fe(III)(OH2)(2) gives IA, indole-3-carboxy lic acid (ICA), 2-oxo-indole-3-carbinol and 3-methylene oxindole. The oxidation of indole-3-propionic acid and indole-3-butyric acid with H2 O2 in the presence of Cl8TPPS4Fe(III)(OH2)(2) in aqueous buffer soluti on as well as AOT reverse micelles do not give the oxidative decarboxy lation products. The formation of IC may be explained by the hydrogen abstraction from IAA by high valent oxo-iron(IV) radical cations follo wed by decarboxylation and subsequent recombination of either free hyd roxy radical or hydroxyiron(III)porphyrin. The same abstraction and re combination mechanism has been proposed for oxidation of IC to IA and IA to ICA.