title: Catalytic activity of ruthenium(III) on the oxidation of an anticholinergic drug-atropine sulfate monohydrate by copper(III) periodate complex in aqueous alkaline medium - decarboxylation and free radical mechanism.
abstract: Atropine sulfate monohydrate (ASM) is an anticholinergic drug, having a wide spectrum of activity. Hence, the kinetics of oxidation of ASM by diperiodatocuperate (DPC) in the presence of micro (10-6) amounts of Ru(III) catalyst has been investigated spectrophotometrically in aqueous alkaline medium at I = 0.50 mol dm-3. The reaction between DPC and ASM exhibits 1:2 stoichiometry (ASM:DPC) i. e., one mole of ASM require two moles of DPC to give products. The main oxidation products were confirmed by spectral studies. The reaction is first order with respect to [DPC] and [Ru(III)], while the order with respect to [ASM] and [OH-] was less than unity. The rates decreased with increase in periodate concentration. The reaction rates revealed that Ru(III) catalyzed reaction was about seven-fold faster than the uncatalyzed reaction. The catalytic constant (KC) was also determined at different temperatures. A plausible mechanism is proposed. The activation parameters with respect to slow step of the mechanism were calculated and the thermodynamic quantities were also determined. Kinetic experiments suggest that [Cu(H2IO6)(H2O)2] is the reactive Cu(III) species and [Ru(H2O)5OH]2+ is the reactive Ru(III) species.
authors.forename: Kirthi S
authors.initials: KS
authors.lastname: Byadagi
authors.forename: Sharanappa T
authors.initials: ST
authors.lastname: Nandibewoor
authors.forename: Shivamurti A
authors.initials: SA
authors.lastname: Chimatadar
mesh_terms: D000468:Alkalies / Q000737:chemistry; D001285:Atropine / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003653:Decarboxylation; D005609:Free Radicals / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D018727:Muscarinic Antagonists / Q000737:chemistry*; D010084:Oxidation-Reduction; D010504:Periodic Acid / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D000468:Alkalies; D005609:Free Radicals; D018727:Muscarinic Antagonists; D014867:Water; D010504:Periodic Acid; D003300:Copper; D001285:Atropine; D012428:Ruthenium