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Reaction of a satirically hindered iron(III) porphyrin with peroxyacetic acid: Degradation kinetics

Prakash P. (Department of Chemistry, Adhiyamaan College of Engineering, Hosur, India)
Francisca Mary L.J. (Department of Chemistry, Anna University, Chennai, India)

A kinetic analysis of the reaction between peracetic acid (AcOOH), and tetrakis (pentafluorophenyl) - 21H, 23H-porphine iron(III) chloride Fe(F20TPP)Cl, in acetonitrile showed that the peracetic acid oxidatively destroys Fe(F20TPP)Cl. This is in contrast to an assumption that the oxidative degradation of metalloporphyrins can be prevented by the introduction of electron-withdrawing substituents into the phenyl groups of the porphyrin ligand. A UV-visible spectroscopic study showed a degree of macro cycle destruction of the tetrapyrrole conjucation of the metalloporphyrin. The degradation takes place via oxoperferryl species. The first step of the reaction mechanism is the reversible formation of an adduct ’X’ (k1/k-1) between Fe(F20TPP)Cl and peracetic acid, followed by an irreversible step (k2) for the formation of oxoperferryl species.

Keywords: substituted iron porphyrin, oxidative degradation, peracetic acid, kinetics and mechanism