title: Kinetics and mechanism of oxidation of chondroitin-4-sulfate polysaccharide by chromic acid in aqueous perchlorate solutions.
abstract: The kinetics of chromic acid oxidation of chondroitin-4-sulfate polysaccharide as sulfated carbohydrates at a constant ionic strength of 4.0 mol dm(-3) has been investigated, spectrophotometrically. The reaction kinetics showed a first-order dependence in chromic acid and fractional-first-order kinetics with respect to the chondroitin-4-sulfate concentration. The influence of [H(+)] on the reaction rates showed that the oxidation process is acid-catalyzed. Added Mn(2+) ions indicated the formation of Cr(IV) as intermediate species. A kinetic evidence for formation of 1:1 intermediate complex was revealed. The kinetic parameters have been evaluated and a tentative reaction mechanism in good consistent with the kinetic results obtained is discussed.
authors: Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt. rmhassan2002@yahoo.com
authors: Refat
authors: R
authors: Hassan
authors: Samia
authors: S
authors: Ibrahim
authors: Abdel Rahman
authors: AR
authors: Dahy
authors: Ishaq
authors: I
authors: Zaafarany
authors: Fahd
authors: F
authors: Tirkistani
authors: Hideo
authors: H
authors: Takagi
mesh_terms: D002809:Chondroitin Sulfates / Q000737:chemistry*; D002840:Chromates / Q000737:chemistry*; D007700:Kinetics; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D010472:Perchlorates / Q000737:chemistry*; D058105:Polymerization; D011522:Protons; D012996:Solutions; D014867:Water / Q000737:chemistry*
chemical_list: D002840:Chromates; D010472:Perchlorates; D011522:Protons; D012996:Solutions; D014867:Water; D002809:Chondroitin Sulfates; C034944:chromic acid; C494474:perchlorate