Kinetics and mechanism of permanganate oxidation of pectin polysaccharide in acid perchlorate media

Autor:	Khalid S. Khairou, Refat M. Hassan, M. I. Abdel-Hamid
Rok vydání:	2003
Předmět:	Reaction mechanism food.ingredient Aqueous solution Polymers and Plastics Pectin Organic Chemistry Permanganate Inorganic chemistry Kinetics General Physics and Astronomy chemistry.chemical_compound Perchlorate food chemistry Ionic strength Materials Chemistry Perchloric acid
Zdroj:	European Polymer Journal. 39:381-387
ISSN:	0014-3057
DOI:	10.1016/s0014-3057(02)00217-3
Popis:	The kinetics of oxidation of pectin polysaccharide as a natural polymer by permanganate ion in aqueous perchloric acid at a constant ionic strength of 2.0 mol dm −3 has been investigated spectrophotometrically. The reaction time curves showed two distinct stages, the initial stage was relatively slow, followed by an increase in the rate of oxidation at longer times. The results of the initial rates reveal first-order kinetics in permanganate ion and fractional-order with respect to pectin concentration. Kinetic evidence for the formation of an intermediate complex between the polysaccharide and the oxidant is presented. The results obtained at various hydrogen ion concentrations showed that the reaction is acid catalyzed. The added salts lead to the prediction that Mn 4+ and/or Mn 3+ play an important role in the autoaccleration period kinetics. A tentative reaction mechanism consistent with the kinetic results is discussed.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::fccb209cda2d5cceb474d64bc0d30038 https://doi.org/10.1016/s0014-3057(02)00217-3 Zobrazit plný text záznamu Full Text from ScienceDirect