Kinetics of oxidation of L-proline by hexacyanoferrate(III) catalyzed by osmium(VIII) in alkaline medium was studied at 30°C. A mechanism involving free radical path was proposed. Rate law of the reaction was derived asThe rate constant k and equilibrium constants K 1 and K 2 were evaluated as 3.79 × 10 3 dm 3 mol -1 s -1 , 0.52 dm 3 mol -1 , and 3.78 × 10 3 dm 3 mol -1 , respectively. The main reactive species of the catalyst appears to be OsO 5 (OH) 3-. The oxidative product of L-proline was identified as L-glutamic acid which is different from the earlier reports. The literature reveals that 4-amino butyric acid, 4-amino butaraldehyde and keto acids were the oxidative products. Activation parameters were evaluated as E a ) 33.5 ( 2 kJ mol -1 , ∆H q ) 31.0 ( 0.2 kJ mol -1 , ∆S q ) -24 ( 1.5 J K -1 mol -1 , ∆G q ) 38.0 ( 2 kJ mol -1 .
The kinetics of oxidation of As III by Fe(CN) 6 3) has been studied spectrophotometrically in 60% AcOH-H 2 O containing 4.0 mol dm )3 HCl. The oxidation is made possible by the difference in redox potentials. The reaction is first order each in [Fe(CN) 63) ] and [As III ]. Amongst the initially added products, Fe(CN) 6 4) retards the reaction and As V does not. Increasing the acid concentration at constant chloride concentration accelerates the reaction. At constant acidity increasing chloride concentration increases the reaction rate, which reaches a maximum and then decreases. H 2 Fe(CN) 6 ) , is the active species of Fe(CN) 6 3) , while AsCl 5 2) in an ascending portion and AsCl 2 + in a descending portion are considered to be the active species of As III . A suitable reaction mechanism is proposed and the reaction constants of the different steps involved have been evaluated.
The kinetics of oxidation of antihypertensive drug, atenolol by diperiodatoargentate(III) (DPA) in a wide range of alkali has been studied spectrophotometrically. In a lower range of [OH 7 ], the periodate had a retarding effect whereas at higher range of [OH 7 ] the rate of reaction was accelerated. In the higher range of [OH 7 ], the periodate had no effect whereas at lower range of [OH 7 ], periodate and product, [Ag(I)] retarded the rate of the reaction. In the entire range of [OH 7 ], the reaction was unit order in [DPA] and fractional order in [ATN]. Mechanisms consistent with the observed kinetic data for both lower and higher ranges of [OH 7 ] were proposed and discussed. The active species of [Ag(III)] was found to be mono periodatoargentate(III) in lower range of [OH 7 ] and dihydroxymonodiperiodatoargentate(III) in the higher range of [OH 7 ]. The hydrolyzed species of atenolol was found to be the active form of atenolol. Mechanisms for both higher and lower range of [OH 7 ] have been proposed. A composite rate law has been derived and verified for different experimental conditions.
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