Oxidation of inositol (INOS) by hexachloroplatinate(IV) complex (HCP) in perchlorate solutions in the presence of palladium(II) catalyst was studied spectrophotometrically. The reaction rate was very slow in the absence of the catalyst. The reaction exhibited a first order dependence on [HCP], and fractional-first order dependences with respect to [INOS], [H+ ] and [Pd(II)]. Increasing ionic strength and dielectric constant was found to increase the oxidation rate. A probable oxidation mechanism has been suggested and the rate-law expression has been derived. Both spectral and kinetic evidences revealed formation of a 1:1 intermediate complex between INOS and Pd(II) prior to the rate-controlling step. The final oxidation product of inositol was identified by both spectral and chemical analyses as the corresponding monoketone derivative, namely inosose. The activation parameters of the second order rate constant were evaluated and discussed

Oxidation kinetics of inositol (INOS) by cerium(IV) has been studied spectrophotometrically in perchlorate medium at fixed ionic strength and temperature. The reaction showed a first order dependence with respect to [Ce(IV)] and less than unit order kinetics in both [H+ ] and [INOS]. Increasing both ionic strength and dielectric constant of the reaction medium increased the oxidation rate. Addition of Ce(III) product had no any significant effect on the oxidation rate. The oxidation product of inositol was identified by both spectroscopic and chemical tools as inosose. A plausible mechanistic scheme for oxidation reaction has been proposed and the rate law associated with the reaction mechanism was derived. The activation parameters of the second order rate constant were calculated and discussed.

The kinetics of oxidation of inositol (INOS) by permanganate ion in both perchloric and sulfuric acids solutions was studied using a spectrophotometric technique at a constant ionic strength of 1.0 mol dm-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 [INOS] were found to be less than unity. The effect of acids concentrations suggests that the reactions were acid-catalyzed with fractionalsecond order kinetics in [H+ ]. 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 inositol were identified by spectral and chemical tools as the corresponding monoketone derivative, namely inosose. Under comparable experimental conditions, the oxidation rate in sulfuric acid was approximately three times higher than that in perchloric acid. Regarding to the second order rate constants of these reactions, the activation parameters have been evaluated and discussed.

Kinetics of oxidation of L-citrulline (Cit) by permanganate ion in both acidic and basic media has been investigated spectrophtometrically at constant ionic strengths and at 25°C. In both media the reactions exhibited first order dependence in [permanganate] and less than unit order dependences in L-citrulline concentration. A fractional-second order dependence with respect to [H+ ] and a fractional-first order dependence with respect to [OH- ] were revealed in acidic and basic media, respectively. Increasing ionic strength in basic medium increased the oxidation rate of L-citrulline, whereas it had a negligible effect on the oxidation rate in acidic medium. The rate-determining step in both media is suggested to involve a oneelectron change, but the stoichiometry (L-citrulline: permanganate) was different, being 5:2 in acidic medium and 1:2 in basic medium. The proposed oxidation mechanisms involve formation of 1:1 intermediate complexes between kinetically active species of both L-citrulline and permanganate ion in pre-equilibrium steps. The final oxidation products of L-citrulline were identified in both acidic and basic media as the corresponding aldehyde (4-(carbamoylamino) butyraldehyde), ammonia and carbon dioxide. The appropriate rate laws are deduced.

Oxidation kinetics of L-citrulline (Cit) by hexachloroplatinate(IV) (HCP) was studied spectrophotometrically in perchloric acid solutions in the presence of ruthenium(III) catalyst at a constant ionic strength of 1.8 mol dm-3 and at 20°C. The reaction rate was very slow in the absence of the catalyst. The reaction showed first order kinetics in both [HCP] and [Ru(III)] and less than unit order with respect to both [Cit] and [H+ ]. Increasing ionic strength and dielectric constant were found to increase the oxidation rate. Both spectral and kinetic evidences revealed formation of an intermediate complex between Lcitrulline and ruthenium(III) 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 of L-citrulline which were identified by both spectroscopic and chemical tools as 4-(carbamoylamino) butyraldehyde, ammonia and carbon dioxide. 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 of the second order rate constant have been evaluated and discussed

The kinetics of permanganate oxidation of Fluorenone Hydrazone (FH) in both perchloric and sulfuric acid solutions was studied spectrophotometrically at a constant ionic strength of 1.5 mol dm-3 and at 20oC. In both acids, the reactions showed a first order dependence with respect to permanganate ion concentration, whereas the orders with respect to fluorenone hydrazone concentration were less than unity. The orders with respect to both perchloric and sulfuric acid concentrations were found to be fractional-second. Variation of either ionic strength or dielectric constant of the medium had no any significant effect on the oxidation rates. The reactions mechanism describing the kinetic data was proposed. In both acids, the main oxidation products of fluorenone hydrazone as confirmed by GC/MS analysis and FT-IR spectroscopy as the corresponding ketone (9H-fluorenone). Under comparable experimental conditions, the oxidation rate of fluorenone hydrazone in perchloric acid was slightly lower than that in sulfuric acid. The activation parameters of the second order rate constants have been evaluated and discussed.

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.