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Amino acid oxidation is fascinating because different oxidants produce diverse compounds. No research has examined how metal catalysts affect amino acid oxidation by diperiodatocuprate (III) (DPC) in micellar environments. This research is crucial to understanding amino acids in redox processes and identifying active species of Ru(III) and DPC. The study will evaluate how cationic surfactant affects Ru(III)‐facilitated L‐phenylalanine (L‐Pheala) oxidation utilizing DPC in an alkaline medium. The reaction's advancement has been assessed employing the pseudo‐first‐order condition as a gauge for [OH−], [DPC], ionic strength, [L‐Pheala], [Ru(III)], [IO4−], [Surfactant], and temperature. L‐Pheala and DPC interact stoichiometrically in a ratio of 1:4. Across the spectrum of concentrations examined, the reported reaction reflects less than unit order kinematics in relation to both [L‐Pheala] (0.61 in the aqueous medium and 0.58 in the CPC micellar medium) and [OH−] (0.47 in the aqueous medium and 0.51 in the CPC micellar medium), first‐order reliance on the [DPC] and [Ru(III)], and negative fractional‐order for [IO4−] (−0.54 in the aqueous medium and −0.56 in the CPC micellar medium). A zero salt effect is suggested by the observed constancy in oxidation rate with the inclusion of electrolytes. The oxidation rate is significantly enhanced by Ru(III) solution (as a catalyst) at ppm concentration. Cetylpyridinium chloride (CPC) micellar media facilitate an additional enhancement (four times) in the rate of the reaction. CPC thus exhibits an excellent compatibility with Ru(III) for the L‐Pheala oxidation using (DPC). [ABSTRACT FROM AUTHOR]

The study investigates the kinetics associated with the oxidation of D-Mannitol (D-Mann) by diperiodatocuprate(III) (DPC) in an aqueous alkaline medium using spectrophotometric method. Reaction medium’s ionic strength was maintained constant at 0.60 mol dm-3. First-order kinetics in [DPC] and less than unit order for [D-Mann] and [alkali] were observed in the reaction. It was of the negative fractional order in [periodate]. It was determined that the reaction of substrate D-Mann with DPC in an alkaline medium shows 1(D-Mann):4(DPC) stoichiometry. Ionic strength of the medium had no effect on the rate of reaction and same was the observation with dielectric constant. The products of reaction were identified by FTIR and confirmed by LC-ESI-MS spectral data. The reaction constants for each step of the mechanism were determined. For the slow step of reaction mechanism, activation parameters were calculated and discussed. Further, thermodynamic quantities for the reactions were also estimated. Based on the literature survey, DPC was chosen for the current study. DPC was prepared by the reported methods as cited in the manuscript. Stable reaction mixtures were prepared in two different reagent bottles and maintained at a desired temperature using a water bath. The reaction between the oxidant DPC and substrate D-Mannitol was spectrophotometrically analyzed by a UV-Vis spectrophotometer. With the help of data obtained, graphs were plotted to obtain kobs for different variations, and the mechanism was synthesized. A rate law for the reaction under investigation was proposed based on the results and mechanism. [ABSTRACT FROM AUTHOR]

The kinetic experiments on ruthenium(III) catalyzed oxidation of caffeine [CAF] with diperiodatocuprate(III) (DPC) [Cu(H2IO6)(H3IO6)]3− and [Ru(H2O)5(OH)]2+ was observed in an aqueous potassium hydroxide having an ionic strength of 0.8 mol dm−3 at 298 K, with and without the catalyst Ru(III). The reaction between caffeine and DPC in aqueous potassium hydroxide solution proceeds in the stoichiometric proportion of 1 : 4. Using a spot test, the oxidation products were separated and identified using LC-MS. The added periodate was seen to decrease the reaction rate. The impact of ionic strength, included resultant products, and the dielectric constant was investigated and activation parameters were evaluated. [ABSTRACT FROM AUTHOR]

A comparative study of uncatalysed and ruthenium(III) catalyzed oxidation of procainamide(PAH) was carried out spectrophotometrically using diperiodatocuprate(III) in aqueous alkali. Stoichiometry observed was 1:2 (PAH: DPC). The reaction was of first order in both catalyzed and uncatalyzed cases, with respect to [DPC] & [Ru(III)], less than unit order in [PAH] and [alkali]. Negative fraction in [periodate]. Other kinetic parameters viz., ionic strength, dielectric constant, temperature effect and intervention of free radical were also studied. The main oxidation products were characterized by different techniques. The activation parameters with respect to slow step of the mechanism, also the thermodynamic quantities were determined. [ABSTRACT FROM AUTHOR]

Autocatalysed oxidation of important amino acid, L-Citrulline(L-Cit) by coordination complex, diperiodatocuprate(III) in aqueous alkaline medium at a constant ionic strength of 0.05 mol dm−3 was studied spectrophotometrically. Autocatalysis was observed by one of the products formed, i.e., Cu (II). 1:4 stoichiometry (L-Cit:DPC) exhibited between the reaction of L-Cit and DPC in aqueous alkaline medium. The path is of first-order in [DPC], less than unit order in [L-Cit] and independent in [OH-]. Periodate has a retarding effect on the rate of reaction. Ionic strength has a negligible effect on the reaction rate. The main reaction products were identified by spot tests and spectroscopic analysis. A composite mechanism involving uncatalysed and an autocatalysed reaction path (via free radical) was proposed. The activation parameters for the slow step of the mechanism and also the thermodynamic quantities for different steps of the mechanism were determined and discussed. SYNOPSIS The oxidation of L-Citrulline by diperiodatocuprate(III) complex has been studied. Autocatalysis was observed by one of the products formed, i.e., Cu (II). 1:4 stoichiometry (L-Cit:DPC) exhibited between the reaction of L-Cit and DPC. A composite mechanism involving uncatalysed and an autocatalysed reaction path (via free radical) was proposed. [ABSTRACT FROM AUTHOR]

The kinetics of the oxidation of ruthenium(III) (Ru(III)) catalyzed oxidation of dimedone (DM) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.05 mol dm–3 was studied spectrophotometrically. The reaction between dimedone and DPC in alkaline medium in presence of [Ru(III)] exhibits 2 : 4 stoichiometry (DM : DPC). The reaction seems to proceed by two different mechanisms. At higher concentrations of alkali, the reaction exhibits first, less than unity, first and zero order dependence of the rate on [DPC], [DM] [Ru(III)] and [alkali], respectively, while at lower concentrations of alkali, all the orders are the same except for [OH–], the order of [OH–] is negative and less than unity. The OH− had retarding effect at lower alkali and added periodate had no effect on the rate of the reaction in both the cases of [OH–], while rate was independent of ionic strength and dielectric constant. Intervention of free radicals was observed in the reaction. The oxidation reaction in alkaline medium has been shown to proceed via a Ru(III)–DM complex, which reacts with diperiodatocuprate(III) species to decompose in a rate determining step followed by other fast steps to give the products. The main product was identified by IR, GC-MS, and LC-MS spectroscopy. Probable mechanism was proposed and discussed. The activation parameters for slow step of the mechanism were computed, discussed and thermodynamic quantities were also calculated. The active species of catalyst and oxidant have been identified. [ABSTRACT FROM AUTHOR]

The synthesis and characteristic of some super normal metal complexes in highest oxidation states are described. The chemiluminescence (CL) reaction mechanism with the complexes as oxidant and enhancing and inhibition effect are discussed. The latest developments and analytical applications of the CL detection in flow injection (FI), high performance liquid chromatography (HPLC) and high performance capillary electrophoresis (HPCE) analysis are reviewed. [ABSTRACT FROM AUTHOR]

Illuminating the complex reactions of molecules in aqueous solution is one of the most important tasks of experimental studies of reaction dynamics. The oxidant diperiodatocuprate(III) (DPC) was used for the oxidation of acebutolol (ACBT) in aqueous alkaline medium, at an ionic strength of 0.30 mol·dm. The stoichiometry was found to be 1:2 ([ACBT]:[DPC]). The order of the reaction with respect to [DPC] was unity when [DPC] << [ACBT], while the orders with respect to [ACBT] and [OH] were less than unity, whereas it was negative less than unity in [ $$ {\text{IO}}_{ 4}^{ - } $$ ] over the concentration range studied. The final products of oxidation were identified by GC-MS analysis. Based on the experimental observations, a plausible mechanism is proposed. The reaction constants involved in the different steps of the reaction mechanism were calculated. The activation parameters and the thermodynamic quantities were determined and discussed. Active species of diperiodatocuprate(III) was found to be monoperiodatocuprate(III), i.e. [Cu(HIO)(HO)]. An understanding of the mechanism allows the chemistry to be interpreted, understood and predicted. [ABSTRACT FROM AUTHOR]

The kinetics of oxidation of piperazine by the copper complex, diperiodatocuprate(III) in alkaline medium was studied at 298 K, at an ionic strength of 2.0 x 10 mol dm . The reaction between piperazine and diperiodatocuprate(III) in aqueous alkaline medium exhibited 1:2 stoichiometry. The oxidation products were identified by UV-Visible, GC-MS and IR spectral studies. In the present study we have obtained different kinetic observations. The reaction exhibited unit order in case of diperiodatocuprate(III), while less than unit order with respect to piperazine. The addition of alkali and periodate retarded the rate of reaction. The effects of added products, ionic strength and dielectric constant on the rate of the reaction were also studied. The active species of diperiodatocuprate(III) in alkaline media is [Cu(OH) (H IO)] . The activation parameters with respect to the rate determining step and the thermodynamic quantities with respect to the equilibrium steps were evaluated and discussed. The plausible mechanism consistent with the experimental results was proposed and discussed in detail. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Spectrophotometric kinetic technique has been used to study the oxidation of losartan by diperiodatocuprate(III) (DPC) in the presence and absence of ruthenium(III) catalyst in aqueous alkaline medium at constant ionic strength of 0.90 mol dm. The stoichiometry of the reaction was found to be 1:2 in both catalyzed and uncatalyzed reactions, i.e., one mole of losartan requires two moles of DPC. The reaction products were identified and characterized by IR, GC-MS, and NMR spectral studies. The reaction shows first-order dependence on [DPC] and [ruthenium(III)] and apparently less than unit order in both losartan and alkali concentrations. The effects of added products, ionic strength, periodate, and dielectric constant on the rate of reaction have been studied. The rate of the reaction increased with increasing [alkali] and decreased with increasing [periodate] in both the cases. The reaction rates revealed that Ru(III) catalyzed reaction was about sevenfold faster than the uncatalyzed reaction. Based on experimental results suitable mechanisms are proposed. The proposed mechanisms and the derived rate law are in concurrence with the observed kinetics. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed, and thermodynamic quantities were also determined. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Captopril is a sulfur containing drug which inhibits angiotensin-converting enzyme. Its kinetics of oxidation were studied spectrophotometrically using diperiodatocuprate(III) in aqueous alkali. Major oxidative product of captopril was identified as captopril disulfide along with trace amount of the hydrolyzed product, l-proline. Kinetics of oxidation was found to be first order each in [oxidant] and [reductant]. Rate of reaction was decreased by increasing [OH], whereas added periodate retarded the rate. Other kinetic parameters viz., ionic strength, dielectric constant, temperature effect, and intervention of free radical were also studied. Activation parameters like E, Δ H, Δ S, Δ G, and log A were calculated. A suitable mechanism was proposed. Rate law for proposed mechanism was derived and verified. Reaction constants involved in various steps of mechanism were evaluated and used to regenerate first-order experimental rate constants at various experimental conditions. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Rhodium(III)Chloride catalyzed oxidation of some aromatic ketones by Diperiodatocuprate(III) (DPC) in aqueous alkaline medium has been studied spectrophotometrically at 414nm. The order in [DPC] is zero and one each in [Rh(III)] and [ketone]. No salt effect and [OH-] effect have been found on the rate of oxidation. The stoichiometric studies reveal that one mole of substrate consumes two moles of DPC giving the corresponding carboxylic acid as the reaction product. A direct reaction between Rh(III) and substrate to give product has been proposed. [ABSTRACT FROM AUTHOR]

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 thermodyna-mic 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. [ABSTRACT FROM AUTHOR]

Rhodium(III)Chloride catalyzed oxidation of some aromatic ketones by Diperiodatocuprate(III) (DPC) in aqueous alkaline medium has been studied spectrophotometrically at 414nm. The order in [DPC] is zero and one each in [Rh(III)] and [ketone]. No salt effect and [OH-] effect have been found on the rate of oxidation. The stoichiometric studies reveal that one mole of substrate consumes two moles of DPC giving the corresponding carboxylic acid as the reaction product. A direct reaction between Rh(III) and substrate to give product has been proposed. [ABSTRACT FROM AUTHOR]

The kinetics of ruthenium(III) catalyzed oxidation of atenolol by diperiodatocuprate(III) in aqueous alkaline medium at a constant ionic strength of I = 0.10 M has been studied spectrophotometrically at 27°C. The reaction between diperiodatocuprate(III) and atenolol in alkaline medium in presence of ruthenium(III) exhibits 2: 1 stoichiometry (atenolol: diperiodatocuprate(III)). The main products were identified by spot test, IR, NMR, and LC-MS. The reaction is of first order in DPC concentrations and has less than unit order in both ATN and alkali concentrations. The order in ruthenium(III) was unity. Intervention of free radicals was observed in the reaction. Increase in periodate concentration decreases the rate. The oxidation reaction in alkaline medium has been shown to proceed via a ruthenium(III)-atenolol complex, which reacts with monoperiodatocuprate(III) in a rate determining step followed by other fast steps to give the products. Probable mechanism is proposed and discussed. The activation parameters with respect to the slow step of the mechanism and thermodynamic quantities were determined and discussed. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation of 6-aminopenicillanic acid (6-APA) by diperiodatocuprate(III) (DPC) has been investigated both in the absence and presence of a ruthenium(III) catalyst in aqueous alkaline medium, at a constant ionic strength of 0.20moldm−3, spectrophotometrically. The stiochiometry was the same in both cases, i.e. [6-APA]/[DPC]=1:2. In both the catalyzed and uncatalyzed reactions, the order of the reaction with respect to [DPC] was unity, while the order with respect to [6-APA] was <1 over the concentration range studied. The rate increased with an increase in [OH−] and decreased with an increase in [] in both cases. The order with respect to [Ru(III)] was unity. The oxidation products were identified by spectral analysis and suitable mechanisms were proposed. The reaction constants involved in the different steps of the reaction mechanisms were calculated for both cases. The catalytic constant (KC ) was also calculated for the catalyzed reaction at different temperatures. The activation parameters with respect to the slow step of the mechanism and also the thermodynamic quantities were determined. Kinetic experiments suggest that [Cu(H2IO6)(H2O)2] is the reactive copper(III) species and [Ru(H2O)5OH]2+ is the reactive Ru(III) species. [Copyright &y& Elsevier]

The kinetics of the oxidation of ruthenium(III)-catalyzed oxidation of pentoxifylline (PTX) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.30 mol dm was studied spectrophotometrically. The reaction between PTX and DPC in alkaline medium in the presence of Ru(III) exhibits 1:2 stoichiometry (PTX:DPC). The reaction was of first order in DPC, less than the unit order in [PTX] and [OH] and negative fractional order in [IO]. The order in [Ru(III)] was unity. Intervention of free radicals was observed in the reaction. The main products were identified by TLC and spectral studies including LC-MS. The oxidation reaction in alkaline medium has been shown to proceed via a Ru(III)-PTX complex, which reacts with monoperiodatocuprate(III) to decompose in a rate determining step followed by a fast step to give the products. The reaction constants involved in different steps of the mechanism were calculated. The activation parameters with respect to the slow step of the mechanism were computed and discussed, and thermodynamic quantities were also determined. The active species of catalyst and oxidant have been identified. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The kinetics of oxidation of 6-mercaptopurine (6-MP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.01 mol/dm3 was studied spectrophotometrically. The reaction between DPC and 6-MP in an alkaline medium exhibits 1:4 stoichiometry (6-MP:DPC). The reaction is of first order in [DPC] and has less than unit order in both [6-MP] and [alkali]. However, the order of [6-MP] and [alkali] changes from first order to zero order as their concentration increases. Intervention of free radicals was observed in the reaction. An increase in periodate concentration decreases the rate. The oxidation reaction in an alkaline medium has been shown to proceed via a monoperiodatocuprate(III)-6-MP complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main oxidative products were identified by spot test, IR, GC-MS and HPLC studies. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to a slow step of the mechanism are computed and discussed, and thermodynamic quantities are also determined. [image omitted] [ABSTRACT FROM AUTHOR]

The kinetics of oxidation of the L-alanine (L-ala) by diperiodatocuprate(III) (DPC) was carried both in the absence and presence of osmium(VIII) catalyst in alkaline medium at constant ionic strength of 0.01 mol dm-3 spectrophotometrically. The involvement of free radicals was observed in both the reactions. The oxidation products in both the cases were acetaldehyde and Cu(II), identified by spot test and spectroscopic studies. The stoichiometry is the same in both cases; that is, [L-ala]:[DPC] = 1:2. The reaction was first order in [DPC] and has negative fractional order in [OH-] in both the catalyzed and uncatalyzed cases. The order in [osmium(VIII)] was unity. A mechanism involving the formation of a complex between L-ala and DPC in case of uncatalyzed reaction and a mechanism involving the formation of a complex between L-alanine and osmium(VIII) in case of catalyzed reaction were proposed. The reaction constants involved in the different steps of the mechanisms were calculated for both reactions. The catalytic constant (Kc) was also calculated for catalyzed reaction at different temperatures. The activation parameters with respect to slow step of the mechanisms were computed and discussed for both the cases. The thermodynamic quantities were also determined for uncatalyzed and catalyzed reactions. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation of a hemorheologic drug, Pentoxifylline (PTX) by diperiodatocuprate(III) (DPC) has been investigated both in the absence and presence of Osmium(VIII) catalyst in aqueous alkaline medium at a constant ionic strength of 0.30moldm−3 spectrophotometrically. The stoichiometry was same in both the cases, i.e., [PTX]/[DPC]=1:2. In both catalyzed and uncatalyzed reactions, the order of the reaction with respect to [DPC] was unity while the order with respect to [PTX] was <1 over the concentration range studied. The rate increased with an increase in [OH−] and decreased with an increase in in both the cases. The order with respect to [Os(VIII)] was unity. The reaction rates revealed that Os(VIII) catalyzed reaction was about sixfold faster than the uncatalyzed reaction. The reaction products were identified by TLC and spectral studies including LC–MS. Suitable mechanisms were proposed. The reaction constants involved in different steps of the reaction mechanisms were calculated for both cases. The catalytic constant (K C) was also calculated for catalyzed reaction at different temperatures. The activation parameters with respect to slow step of the mechanism and also the thermodynamic quantities were determined. Kinetic experiments suggest that [Cu(H2IO6)(H2O)2] is the reactive copper(III) species and [OsO4(OH)2]2− is the reactive Os(VIII) species. [ABSTRACT FROM AUTHOR]

Oxidation of the amino acid l-phenylalanine by diperiodatocuprate(III) in alkaline medium at constant ionic strength of 0.25 mol dm was studied spectrophotometrically at different temperatures (298-313 K). The reaction between diperiodatocuprate(III) and l-phenylalanine in alkaline medium exhibits 1:2 stoichiometry. Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidence, a mechanism involving monoperiodatocuprate(III) as the reactive oxidant species has been proposed, proceeding through the formation of a complex and reaction of the intermediate of l-phenylalanine with monoperiodatocuprate(III) to give the products. The products were identified by spot test, infrared (IR), and gas chromatography-mass spectrometry (GC-MS). The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to the slow step of the mechanism were computed and are discussed. The thermodynamic quantities were determined for different equilibrium steps. The isokinetic temperature was also calculated and found to be 331 K. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: The kinetics of oxidation of a non-steroidal analgesic drug, aspirin (ASP) by diperiodatocuprate(III)(DPC) in the presence and absence of osmium(VIII) have been investigated at 298K in alkaline medium at a constant ionic strength of 0.10moldm−3 spectrophotometrically. The reaction showed a first-order in [DPC] and less than unit order in [ASP] and [alkali] for both the osmium(VIII) catalysed and uncatalysed reactions. The order with respect to Os(VIII) concentration was unity. The effects of added products, ionic strength, periodate and dielectric constant have been studied. The stoichiometry of the reaction was found to be 1:4 (ASP:DPC) for both the cases. The main oxidation product of aspirin was identified by spot test, IR, NMR and GC–MS. The reaction constants involved in the different steps of the mechanisms were calculated for both reactions. Activation parameters with respect to slow step of the mechanisms were computed and discussed for both the cases. The thermodynamic quantities were also determined for both reactions. The catalytic constant (K C) was also calculated for catalysed reaction at different temperatures and the corresponding activation parameters were determined. [Copyright &y& Elsevier]

Abstract: The kinetics of oxidation of atenolol (ATN) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10moldm−3 was studied spectrophotometrically. The reaction between DPC and ATN in alkaline medium exhibits 1:2 stoichiometry (ATN:DPC). The reaction is of first order in [DPC] and has less than unit order in both [ATN] and [alkali]. However, the order in [ATN] and [alkali] changes from first order to zero order as their concentration increase. Intervention of free radicals was observed in the reaction. Increase in periodate concentration decreases the rate. The oxidation reaction in alkaline medium has been shown to proceed via a monoperiodatocuprate(III)–ATN complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main oxidative products were identified by spot test, IR, NMR and LC–ESI-MS studies. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed, and thermodynamic quantities are also determined. [Copyright &y& Elsevier]

Abstract: The oxidation of dl-ornithine monohydrochloride (OMH) by diperiodatocuprate(III) (DPC) has been investigated both in the absence and presence of ruthenium(III) catalyst in aqueous alkaline medium at a constant ionic strength of 0.20moldm−3 spectrophotometrically. The stiochiometry was same in both the cases, i.e., [OMH]/[DPC]=1:4. In both the catalyzed and uncatalyzed reactions, the order of the reaction with respect to [DPC] was unity while the order with respect to [OMH] was <1 over the concentration range studied. The rate increased with an increase in [OH−] and decreased with an increase in [IO4 −] in both cases. The order with respect to [Ru(III)] was unity. The reaction rates revealed that Ru(III) catalyzed reaction was about eight-fold faster than the uncatalyzed reaction. The oxidation products were identified by spectral analysis. Suitable mechanisms were proposed. The reaction constants involved in the different steps of the reaction mechanisms were calculated for both cases. The catalytic constant (K C) was also calculated for catalyzed reaction at different temperatures. The activation parameters with respect to slow step of the mechanism and also the thermodynamic quantities were determined. Kinetic experiments suggest that [Cu(H2IO6)(H2O)2] is the reactive copper(III) species and [Ru(H2O)5OH]2+ is the reactive Ru(III) species. [Copyright &y& Elsevier]

Abstract: Oxidation of penicillin derivative, ampicillin (AMP) by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of 0.01-moldm−3 was studied spectrophotometrically. The reaction between DPC and ampicillin in alkaline medium exhibits 1:4 stoichiometry (ampicillin:DPC). Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidences, a mechanism involving the protonated form of DPC as the reactive oxidant species has been proposed. The oxidation reaction in alkaline medium has been shown to proceed via a DPC–AMP complex, which decomposes slowly in a rate determining step to yield phenyl glycine (PG) and free radical species of 6-aminopenicillanic acid (6-APA), followed by other fast steps to give the products. The two major products were characterized by IR, NMR, LC–MS and Spot test. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed and thermodynamic quantities were also determined. [Copyright &y& Elsevier]

The kinetics of osmium(VIII) and ruthenium(III) catalysed oxidation of l-lysine ( l-lys) by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of 0.15 mol dm−3 was studied spectrophotometrically. The reaction between l-lys and DPC in alkaline medium exhibits 1:2 stoichiometry in both catalysed reaction ( l-lys: DPC). The reaction is first order in [DPC] and has less than unit order both in [ l-lys] and [alkali]. Increase in periodate concentration decreases the rate. Intervention of free radicals was observed in the reaction. The main products were identified by spot test, IR and GC-MS studies. Probable mechanisms are proposed and discussed. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to the slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined. It has been observed that the catalytic efficiency for the present reaction is in the order of Os(VIII) > Ru(III). The active species of catalyst and oxidant have been identified. The kinetic and mechanistic investigations of the reaction between DPC and l-lysine has been studied in presence of microamounts of ruthenium(III) and osmium(VIII) in alkaline medium. The monoperiodatoargentate(III), [Ru(H2O)5OH]2+ and [OsO4(OH)2]2− are considered as the active species of oxidant, DPC, ruthenium(III) and osmium(VIII) respectively. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The kinetics of oxidation of 3-amino-1-propanol (3-AP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium have been studied by spectrophotometry in the temperature range 298.2 K-313.2 K. The reaction was found to be pseudo-first order with respect to DPC and 1> [DPC]0), the observed rate constant kobs changed differently under different concentration of [OH-]. At low [OH-], kobs decreased with increase in [OH-], but at higher [OH-], kobs increase with increase in [OH-], and periodate had a retarding effect on the reaction rate. There is a weak negative salt effect. The main products were identified by spot tests. Based on the experimental results, a probable reaction mechanism of oxidation is proposed. The rate equation derived from the mechanism can explain all the experimental phenomena. The activation parameters, along with the rate constants of the rate-determining step, were determined. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation of a neuroleptic drug gabapentin (GP) by a new oxidant diperiodatocuprate(III) (DPC) has been studied in an aqueous alkaline medium. A minute amount (10−7 moldm−3) of ruthenium(III) is sufficient to catalyse the reaction. The reaction is first order in [DPC] in the presence of ruthenium(III). The order in [GP] is less than unity, whereas that in [Ru(III)] is unity. Increase in [OH−] accelerates the reaction rate. A plausible mechanism involving the active species of oxidant and catalyst is proposed. The reaction constants in the mechanism have been evaluated. [Copyright &y& Elsevier]