A promising methyl ester of pectic acid polysaccharide in biomedicine and pharmaceutics applications: Oxidation of methyl ester of pectic acid by alkaline hexacyanoferrate(III). A kinetic and mechanistic orientation

The oxidation of methyl ester of pectic acid (pectin) (PEC) by a hexacyanoferrate(III) ion at a constant ionic strength of 0.1 mol dm⁻³ has been investigated spectrophotometrically. The oxidation rates were found to increase with increasing the alkali concentration, indicating that the nature of reaction was base catalyzed. The agreement of [pectin] dependence of the rate constants to the Michaelis-Menten kinetics proves the formation of 1:1 intermediate complex prior to the rate-determining step. The deviation of the pseudo–first-order curves from linearity after 65-70% of reaction completion indicates the interference of some oxidation products during the reaction progression. The oxidation process was proceeding via a free-radical intervention mechanism. The activation parameters have been evaluated, and a suitable reaction mechanism is suggested and discussed.