Biomimetic oxidation of ibuprofen with hydrogen peroxide catalysed by horseradish peroxidase (HRP) and 5,10,15,20- tetrakis-(2′,6′-dichloro-3′-sulphonatophenyl)porphyrinatoiron(III) and manganese(III) hydrates in AOT reverse micelles

Abstract

The oxidation of ibuprofen with H2O2 catalysed by Horseradish peroxidase (HRP), Cl8TPPS4Fe(III)(OH2)2 and Cl8TPPS4Mn(III)(OH2)2 in AOT reverse micelles gives 2-(4′-isobutyl-phenyl)ethanol (5 ) and p-isobutyl acetophenone (6) in moderate yields. The reaction of ibuprofen (2) with H2O2 catalysed by HRP form carbon radicals by the oxidative decarboxylation, which on reaction with molecular oxygen to form hydroperoxy intermediate, responsible for the formation of the products 5 and 6. The yields of different oxidation products depend on the pH, the water to surfactant ratio (Wo), concentration of Cl8TPPS4Fe(III)(OH2)2 and Cl8TPPS4Mn(III)(OH2)2 and amount of molecular oxygen present in AOT reverse micelles. The formation of 2-(4′-isobutyl phenyl)ethanol (5) may be explained by the hydrogen abstraction from ibuprofen by high valent oxo-manganese(IV) radical cation, followed by decarboxylation and subsequent recombination of either free hydroxy radical or hydroxy iron(III)/manganese(III) porphyrins. The over-oxidation of 5 with high valent oxo-manganese, Mn(IV)radical cation intermediate form 6 in AOT reverse micelles by abstraction and recombination mechanism.