Novel Carboxymethyl Cellulose Ionotropic Gels

Kinetics and mechanism of decomposition of intermediate complex during oxidation of pectate polysaccharide by potassium permanganate in alkaline solutions

“…Similar reaction mechanisms were observed during the oxidation of alginates 1, 4, poly(vinyl alcohol) 3, 5, carboxymethyl cellulose 20, 21, and starch (A. M. Shaker, private communication) as polymers containing secondary alcoholic groups by this oxidant in strongly alkaline solutions. Leffler and Grunwald 22 have pointed out that many redox reactions show an isokinetic relationship Δ H ≠ = α + β Δ S ≠ .…”

Kinetics and mechanism of the decay of methyl cellulose‐manganate(VI) polysaccharide transient species–novel spectrophotometric kinetic trace of methyl cellulose hypomangate(V) gel intermediate polysaccharide

“…The reaction kinetics were followed by monitoring the decrease in the absorbance at 610 nm, the absorption peak of the green [MC‐Mn VI O] intermediate complex as a function of time. As reported elsewhere4, 10, 11 when the green intermediate builds up to maximum concentration, it commences to decompose and the corresponding absorbance at λ max = 610 nm decreases. Absorbance values and spectral scans were recorded in a Cecil CE 599 automatic scanning spectrophotometer connected to a CE 836 cell and wavelength programmer.…”

“…The blue hypomanganate(V) complex has been detected elsewhere5–9 by stopped‐flow techniques. Shaker10 could detect and for the first time, spectroscopically observable trace for hypomanganate(V) intermediate complex of carboxymethyl cellulose at 700 nm. El‐Khatib11 published before kinetics and mechanism of the oxidation of methyl cellulose via the formation of its manganate(VI) transient species.…”

Spectrophotometric evidence for the formation of short-lived hypomanganate(V) and manganate(VI) transient species during the oxidation of K-carrageenan by alkaline permanganate

“…This fact can be ascribed to the extremely short lifetime owing to fast disproportionation. [1][2][3][4][5] However, Shaker 6,7 and El-Khatib 8 pointed out the rapid formation of Mn V as a short-lived intermediate complex during kinetic studies on the oxidation of some polysaccharides containing secondary hydroxyl groups such as carboxymethyl cellulose and methyl cellulose. Information about the characteristics of these transient species and the mechanism of oxidation is still lacking.…”

“…1 is autocatalyzed by the presence of Mn IV . 1,5 The formation of Mn VI and/or Mn V as short-lived intermediates have been postulated by many investigators during the oxidation of macromolecules [6][7][8][17][18][19][20][21][22] or organic substrates 14,16 by permanganate ion in alkaline solutions. The formation of long-lived hypomanganate(V) is conceivable only with sterically rigid olefines, 4,23 and sulfite ion.…”