The effect of ruthenium(III) catalyst on the kinetics of oxidation of atropine drug (ATR) by chromic acid in perchlorate solutions was studied spectrophotometrically at a fixed ionic strength of 1.0 mol dm-3 and at 25°C. Both uncatalyzed and Ru(III)-catalyzed oxidation reactions showed a first order dependence in [Cr(VI)], and less than unit order dependences with respect to both [ATR] and [H+]. The reaction was first order in [Ru(III)]. The effects of both ionic strength and dielectric constant of the reactions medium were investigated. Addition of Mn(II) was found to decrease the oxidation rate. The rate of Ru(III)-catalyzed oxidation of atropine was found to be about 10-fold higher than that of the uncatalyzed reaction. In both cases, the main oxidation products of atropine were identified as tropine, benzaldehyde, methanol, and carbon dioxide. Plausible mechanisms for both uncatalyzed and Ru(III)- catalyzed oxidations were proposed and the rate-law expressions associated with these mechanisms were derived. The activation parameters related to the second order rate constants were evaluated and discussed.

The kinetics of oxidations of atropine (ATR) by permanganate ion in both perchloric and sulfuric acid solutions was studied using spectrophotometric technique at a constant ionic strength of 1.2 moldm-3 and at 25°C. In both acids, the reactions showed a first order dependence with respect to [permanganate], whereas the orders with respect to [ATR] and [H+ ] were found to be less than unity. The effect of acid concentration suggests that the reactions were acid-catalyzed. Variation of either ionic strength or dielectric constant of the medium had no effect significantly on the oxidation rates. The reactions mechanism adequately describing the kinetic results was proposed. In both acids, the main oxidation products of atropine were identified by spectral and chemical analyses as tropine and phenylmalonic acid. Under comparable experimental conditions, the oxidation rate of atropine in sulfuric acid was approximately three times higher than that in perchloric acid. The reactions constants involved in the different steps of the reactions mechanism have been evaluated. With admiration to the rate-limiting step of these reactions, the activation parameters have been evaluated and discussed.

The kinetics of oxidation of atropine drug (ATR) by cerium(IV) in aqueous perchlorate solutions in the presence of silver(I) catalyst has been studied spectrophotometrically at a constant ionic strength and temperature. The reaction showed first order dependence with respect to each [Ce(IV)] and [Ag(I)], and less than unit order kinetics with respect to [ATR]. The reaction exhibited negative fractional-first order kinetics with respect to [H+ ]. Increasing ionic strength and dielectric constant of the medium increased the reaction rate. In the present work, the kinetically active species of cerium(IV) was found to be Ce(OH)3+. Addition of Ce(III) product had no significant effect on the oxidation rate. The oxidation products of atropine were identified by spectral and chemical analyses as tropine, benzaldehyde, methanol and carbon dioxide. A plausible mechanistic scheme for the catalyzed oxidation was proposed. The activation parameters of the second order rate constant were calculated and the rate law associated with the reaction mechanism was derived.

The influence of silver(I) catalyst on the oxidation of L-glutamine (Gln) by cerium(IV) in perchlorate solutions was studied spectrophotometrically. The study was carried out at a constant ionic strength of 1.0 mod dm-3 and a temperature of 25o C. In both uncatalyzed and Ag(I)-catalyzed paths, the reactions exhibited first order kinetics with respect to [Ce(IV)] and [Ag(I)], and less than unit order with respect to [Gln]. The reactions exhibited negative fractional-first order kinetics with respect to [H+]. Increasing both ionic strength and dielectric constant increased the oxidation rates. Addition of cerium(III) ion as a reaction product did not affect the rates. The rate of Ag(I)-catalyzed oxidation was found to be about seven times higher than that of uncatalyzed one. Ce(OH)3+ was suggested to be the kinetically active species of cerium(IV) under the experimental conditions. Probable mechanistic schemes for both uncatalysed and catalysed reactions are proposed. In both paths, the final oxidation products of L-glutamine are identified as formyl propanamide, ammonium ion, and carbon dioxide. The rate-law expressions consistent with the reactions mechanisms are derived. The activation parameters are evaluated and discussed.

The oxidation kinetics of fluorene (Fl) and its halogenated derivatives, namely, 2,7-dichlorofluorene (Fl-Cl), 2,7- dibromofluorene (Fl-Br) and 2,7-diiodofluorene (Fl-I), using potassium permanganate in alkaline medium has been studied spectrophotometrically at a constant ionic strength of 0.1 mol dm-3 and at 25°C. A first order kinetics has been observed in these reactions with respect to [permanganate]. Fractional-first order dependences of the reactions on the [reductants] and [alkali] were revealed. No significant effect on the reaction rates by increasing ionic strength was recorded. Intervention of free radicals was observed in the reactions. The reactions mechanism describing the kinetic results has been proposed which involves formation of 1:1 intermediate complexes between fluorene derivatives and the active species of permanganate. The final reactions products were identified by GC/MS and FT-IR analyses in all cases as the corresponding ketones (9Hfluorenone derivatives). Under comparable experimental conditions, the order of the oxidation rate of fluorine derivatives was: Fl > Fl-I > Fl-Br > Fl-Cl. The reactions constants involved in the different steps of the reactions mechanism have been evaluated. With admiration to rate-limiting step of these reactions, the activation parameters were recorded and discussed

The kinetics of oxidation of L-glutamine (Gln) by permanganate ion has been investigated in alkaline medium at a constant ionic strength of 0.2 mol dm-3 and at 25o C using spectrophotometric technique. A first order kinetics with respect to [permanganate] and less than unit order dependences on [Gln] and [OH- ] were revealed. No pronounced effect on the reaction rate by increasing either ionic strength or solvent polarity of the medium was recorded. Intervention of free radicals was observed in the reaction. The reaction mechanism describing the kinetic results was suggested. The final oxidation products of L-glutamine were identified as formyl propanamide, ammonia and carbon dioxide. The rate-law expression for the oxidation reaction was deduced and the reaction constants have been evaluated. The activation parameters associated with the rate-limiting step of the reaction, along with the thermodynamic quantities of the equilibrium constants have been calculated and discussed

Oxidations of two aliphatic α-amino acids (AA), namely, leucine and isoleucine by hexachloroplatinate (IV) as an anticancer platinum (IV) complex has been studied using a spectrophotometric technique in perchlorate solutions in the presence of palladium (II) catalyst at a constant ionic strength of 1.0 mol dm-3 and at 25°C. The reactions did not proceed in the absence of the catalyst. The reactions of both amino acids showed a first order dependence on both [PtIV] and [PdII], and less than unit order dependences with respect to both [AA] and [H+ ]. Increasing ionic strength and dielectric constant of the reactions medium increased the rates of the reactions. A probable oxidations mechanism has been suggested and the rate law expression has been derived. Both spectral and kinetic evidences revealed formation of 1:1 intermediate complexes between AA and PdII before the rate-controlling step. The oxidation products of the investigated amino acids were identified as the corresponding aldehyde, ammonium ion and carbon dioxide. The activation parameters of the second order rate constants were evaluated and discussed

The kinetics of oxidations of two aliphatic α-amino acids (AA), namely, alanine and valine by platinum (IV) has been investigated spectrophotometrically in perchloric and sulfuric acids solutions in the presence of silver (I) catalyst at a constant ionic strength of 1.0 mol dm-3 and at 25°C. The reactions were very slow to be measured in the absence of the catalyst. The reactions in both acids showed a first order dependence on both [PtIV] and [AgI ], and less than unit order dependences with respect to both [AA] and [H+ ]. Increasing ionic strength was found to decrease the oxidation rates. Under comparable experimental conditions, the oxidation rates of alanine and valine in perchloric acid solutions were found to be about five times higher than those obtained in sulfuric acid solutions and the oxidation rates of alanine in both acids were found to be higher than those recorded with respect to valine. A plausible oxidations mechanism has been proposed and the rate law expression has been derived. Both spectral and kinetic evidences revealed formation of 1:1 intermediate complexes between AA and AgI in both acids before the rate-controlling step. Then the formed complexes react with the oxidant (PtIV) by an inner-sphere mechanism to give rise to the oxidation products of the amino acids which were identified as the corresponding aldehyde, ammonium ion and carbon dioxide. The activation parameters of the second order rate constants were evaluated and discussed.

The kinetics of oxidations of α-aminobutyric acid (ABA) by platinum(IV) has been investigated spectrophotometrically in perchloric and sulfuric acids solutions in the presence of silver(I) catalyst at a constant ionic strength of 1.0 mol dm-3 and at 25o C. The reactions were very slow to be measured in the absence of the catalyst. The reactions in both acids showed a first order dependence on [PtIV] and less than unit order dependences with respect to [ABA], [H+] and [AgI ]. Increasing ionic strength and dielectric constant was found to decrease the oxidation rates. Under comparable experimental conditions, the oxidation rate of α-aminobutyric acid in perchloric acid solutions was approximately found to be twice that recorded in sulfuric acid solutions. A plausible oxidations mechanism has been proposed and the rate law expression has been derived. Both spectral and kinetic evidences revealed formation of 1:1 intermediate complexes between ABA and AgI in both acids before the rate-controlling step. Then the formed complexes react with the oxidant (PtIV) by an inner-sphere mechanism to give rise to the oxidation products of ABA which were identified as the corresponding aldehyde (propionaldehyde), ammonium ion and carbon dioxide. The activation parameters of the second order rate constants were evaluated and discussed

The kinetics of oxidation of vanillin (VAN) by hexachloroplatinate(IV) has been investigated in perchloric acid solutions in the presence of ruthenium(III) catalyst at a constant ionic strength of 1.0 mol dm-3 and at 25°C. The progress of the reaction was followed spectrophotometrically. The reaction was not proceeding in the absence of the catalyst. The reaction exhibited first order kinetics with respect to both [HCP] and [Ru(III)] and less than unit order with respect to both [VAN] and [H+ ]. Increasing ionic strength and dielectric constant were found to increase the oxidation rate. The reaction mechanism adequately describing the kinetic results has been proposed. Both spectral and kinetic evidences revealed formation of an intermediate complex between vanillin substrate and ruthenium(III) catalyst prior to the rate-determining step. The complex reacts with the oxidant (HCP) by an inner-sphere mechanism leading to decomposition of the complex in the rate-determining step to give rise to the final oxidation products which were identified by both spectral and chemical analyses as vanillic acid and tetrachloroplatinate(II). The rate law expression for the catalyzed reaction was deduced. The reaction constants involved in the different steps of the reaction mechanism have been evaluated. The activation parameters associated with the rate-limiting step of the reaction, along with the thermodynamic quantities of the equilibrium constant have been evaluated and discussed.