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

Abstract

The kinetics of decomposition of an [Pect·Mn VI O 4 2− ] intermediate complex have been investigated spectrophotometrically at various temperatures of 15-30 • C and a constant ionic strength of 0.1 mol dm −3 . The decomposition reaction was found to be first-order in the intermediate concentration. The results showed that the rate of reaction was basecatalyzed. The kinetic parameters have been evaluated and found to be S = = −190.06 ± 9.84 J mol −1 K −1 , H = = 19.75 ± 0.57 kJ mol −1 , and G = = 76.39 ± 3.50 kJ mol −1 , respectively. A reaction mechanism consistent with the results 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

“…Therefore, all present experimental runs were performed under the conditions of [PEC] 0 < 10 −2 mol dm −3 . Similar behavior was observed in some redox reactions involving pectin polysaccharide as a reducing agent …”

“…The reaction time curves were found to be of complex nature where the plots of ln (absorbance) against time gave straight lines up to 65‐70% of reaction completion, then it deviates from linearity at longer time periods (Figure ). This deviation may be attributed to the interference of one of the oxidation products or to the salt effect …”

Kinetic Investigation of the Autocatalytic Reaction between Potassium Permanganate and Hydrogen Peroxide with Soft-modeling Methods

“…(5) and (6). From these mechanisms, we can clearly see that the formation of Mn(II) plays the key role in increasing the rate of Mn(VII).…”

“…Once the formation of Mn(II) is blocked, the rate of Mn(VII) will decrease as shown in Eq. (6). In the following sections, some abnormal phenomena in the reaction that have been observed are explained under various conditions.…”

“…[1][2][3] Nevertheless, permanganate oxidation requires complex and multi-step processes. After the successful observation of its autocatalytic characteristics in the 19th century, 4 many researchers have focused on its kinetic processes and tried to make out the mechanisms in permanganate reacting with different organic or inorganic reagents, [5][6][7] especially with the environmental contaminations 8,9 and some biological molecules. 10,11 During the reaction processes, manganese with different valence states were produced, which were regarded as various intermediates and were influenced by different pH values, temperatures, reagent concentrations, etc.…”