Oxidation of Some Macromolecules. Kinetics and Mechanism of Oxidation of Methyl Cellulose Polysaccharide by Permanganate Ion in Acid Perchlorate Solutions

Abstract

The kinetics of oxidation of methyl cellulose polysaccharide by acidic permanganate at a constant ionic strength of 2.0 mol dm −3 has been investigated, spectrophotometrically. Pseudo-first-order plots showed two distinct stages. The first stage was found to be relatively slow which corresponded to the formation of the substrate radical and Mn 3+ or Mn 4+ species as initial oxidation products, followed by an increase in the reaction rate at longer time periods. The reaction kinetics showed first-order dependence in permanganate and fractional second-order kinetics with respect to methyl cellulose concentration. The hydrogen ion dependence of the reaction rates indicated that the oxidation process is acid catalyzed. The induced polymerization of acrylonitrile indicated the intervention of free-radical mechanism. A kinetic evidence for the formation of 1:2 intermediate complex between the oxidant and the reductant, respectively, was revealed. The activation parameters have been evaluated, and a tentative reaction mechanism consistent with the kinetic results obtained is discussed.

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

“…In view of the forgoing arguments and our interest in the oxidation of polysaccharides by various oxidants in both alkaline and acidic media [27][28][29][30][31][32][33][34] in particular by the alkaline hexacyanoferrate(III) as an oxidant [19][20][21] in a series of investigations in our laboratory, we are prompted to undertake the present investigation of oxidation of methyl ester of pectic acid (pectin) by alkaline [Fe(CN) 6 ] 3− with the aim to verify and rectify the errors in derivation of rate-law expression of this redox reaction, which is reported elsewhere, 26 as well as to elucidate a suitable oxidation mechanism consistent with the kinetic results obtained. Again, this investigation aims to shed some light on the nature of electron-transfer mechanism and transition states in the rate-determining step in comparison to that reported for oxidation of the other polysaccharides by this oxidant in alkaline solutions earlier.…”

Base-Catalyzed Oxidation of Aminotriazole Derivative by Permanganate Ion in Aqueous Alkaline Medium: A Kinetic Study

“…Many investigators [8][9][10][11][12][13][14][15][16][17] have suggested that most of the oxidation reactions by permanganate ion in neutral and alkaline media proceed through intermediate complex formation between the oxidant and substrate. Spectroscopic evidence for such a complex was obtained from the UV-Vis spectra, Fig.…”

Kinetics and mechanistic aspects on electron‐transfer process for permanganate oxidation of poly(ethylene glycol) in aqueous acidic solutions in the presence and absence of Ru(III) catalyst

“…All materials used were of analytical grade. A stock solution of the permanganate ion was prepared, stored, and standardized by the conventional methods described elsewhere . A stock solution of perchloric acid (HClO 4 ) was prepared from BDH‐grade perchloric acid of concentration 70% by weight, specific gravity = 1.66, and molarity = 11.6 in bidistilled water.…”

“…1 Therefore, it is extensively used as a good carrier polymer for drug delivery in medicine industry such as cancer-drug delivery and target diagnostics. 2 The kinetics and mechanisms of oxidation of natural polymers such as polysaccharides by the permanganate ion as a multivalent oxidant in both aqueous acidic 3 and alkaline 4 solutions was the subject of many investigators; a little attention has been paid to the oxidation of synthetic polymers such as poly(vinyl alcohol). 5 Indeed, the oxidation of PEG by the cerium(IV) ion as one-equivalent oxidant has been studied elsewhere.…”