Pectate polyelectrolyte ionotropic gels 1. Kinetics and mechanisms of formation of manganate (VI)-pectate intermediate complex during the oxidation of pectate polysaccharide by alkaline peumanganate

The kinetics of formation of the [Pect (MnO42-)-O-VI] intermediate complex formed during the oxidation of pectate polysaccharide by permanganate ions in alkaline solutions at pH greater than or equal to 12 have been measured by a conventional spectrophotometric technique. The reaction showed a first -order dependence on permanganate concentration and a fractional order with respect to the pectate concentration for the complex formation. Kinetic an d spectrophotometric evidence revealed the formation of manganate (VI) tran sient species. The results obtained indicated that the rate of formation is base catalyzed. Thermodynamic parameters were evaluated and a suitable mec hanism consistent with the kinetic results was suggested. (C) 2000 Publishe d by Elsevier Science Ltd. All rights reserved.