Base-catalyzed oxidation: Kinetics and mechanism of hexacyanoferrate (III) oxidation of methyl cellulose polysaccharide in alkaline solutions

The kinetics of oxidation of methyl cellulose polysaccharide as a natural polymer by alkaline potassium ferricyanide at a constant ionic strength of 1.0 mol dm−3 have been studied, spectrophotometrically. The experimental results showed complex kinetics where the pseudo first-order plots were found to be straight lines up to 60% of reaction completion, and then deviated from linearity. A first-order dependence in Fe(CN)63− and fractional first-order kinetics with respect to the methyl cellulose concentration was observed. The oxidation reaction was found to be base catalyzed. Again, addition of Fe(CN)64− product to the reaction mixture leads to a remarkable retardation of the oxidation rates. A kinetic evidence for the formation of 1:1 intermediate complex was revealed. The activation parameters have been evaluated and a tentative reaction mechanism in good consistency with the kinetic results is discussed.

The kinetics of oxidation of methyl cellulose polysaccharide as a natural polymer by alkaline potassium ferricyanide has been studied, spectrophotometrically. A kinetic evidence for the formation of 1:1 intermediate complex was revealed. The activation parameters have been evaluated and a tentative reaction mechanism is discussed.Figure optionsDownload high-quality image (117 K)Download as PowerPoint slideHighlights
► A kinetic study of the oxidation of some natural polymeric compounds such as methyl cellulose polysaccharides by alkaline ferricyanide (III).
► A novel synthesis of diketo-derivatives of methyl cellulose by an oxidation method.
► Examining the behavior of polysaccharides containing alcoholic groups in aqueous alkaline solutions.
► Elucidation of reaction mechanism for the oxidation process of the cited work.