Santosh K. Upadhyay

Kinetics and mechanism of the ruthenium(III) catalysed oxidation of reducing sugars by chloramine-T in alkaline medium

The kinetics of the ruthenium(III) catalysed oxidation of reducing sugars, viz. arabinose, xylose, galactose, glucose, fructose, lactose and maltose by chloramine-T have been studied in alkaline medium. The reactions exhibit a first order rate dependence with respect to: [substrate], [chloramine-T] and [OH−]. The rate is proportional to {k′ + k″[RuIII]}, where k′ and k″ are rate constants for uncatalysed and catalysed path respectively. A suitable mechanism, consistent with the kinetic data, is proposed and discussed.

Inhibition of TX‐100 on the Rate of Hexacyanoferrate(III) Oxidation of Reducing Sugars: A Kinetic Study

An inhibition effect of nonionic micelles (polyoxyethylene (10) octyl phenol, commonly known as TX‐100) on the rate of oxidation of the reducing sugars, fructose, glucose, and maltose by alkaline hexacyanoferrate(III) has been observed. The kinetic data support a 1:1 association/binding between substrate and micelles. The binding constant and free energy transfer from water to micelle have been determined.

Kinetics and mechanism of palladium(II) catalysed oxidation of amines and aminoalcohols by N-bromosuccinimide in perchloric acid

SummaryThe kinetics of oxidation of amines (EtNH2, Et2NH, Et3N) and aminoalcohols [H2NCH2CH2OH, H2N(CH2)3OH, (CH2CH2OH)2NH, (CH2CH2OH)3N] by N-bromosuccinimide (NBS) have been studied in aqueous HClO4 with PdCl2 as catalyst, and in the presence of Hg(OAc)2 to ensure oxidation by pure NBS. The order of reaction with respect to NBS was unity, however, an increase in [NBS]0 resulted in a decrease in the rate constant. The rate was directly proportional to [PdII] for the aminoalcohols while for EtNH2 the rate was proportional to k + k″[PdII] (where k and k″ are rate constants for the uncatalysed and catalysed paths, respectively). Retarding effects for HClO4, succinimide, Cl− and AcOH on the rate of oxidation were observed. The kinetic data support the formation of [PdII-A] and [PdII-(A)2] complexes (where A represents amine or aminoalcohol). A mechanism, consistent with the observed kinetic data, is proposed.

Kinetics and mechanism of the ruthenium(III)-catalyzed oxidation of hydroxy-acids byN-bromosuccinimide

SummaryThe kinetics of the RuIII-catalyzed oxidation of the hydroxy acids; lactic, tartaric, malic and citric acids byN-bromosuccinimide in HClO4 and in the presence of Hg(OAc)2 have been studied. The reactions exhibit a first order rate dependence with respect to the oxidant and zeroth order rate dependence with respect to substrate. The rate is retarded by [H+], accelerated at law RuIII concentrations but independent of [RuIII] at higher RuIII concentrations. A mechanism consistent with the observed kinetic data is proposed.

Kinetics and mechanism of the ruthenium(III)-catalysed oxidation of aminoalcohols by alkaline hexacyanoferrate(III)

SummaryThe kinetics of the ruthenium(III)-catalysed oxidation of aminoalcoholsviz. 2-aminoethanol and 3-aminopropanol by alkaline hexacyanoferrate(III) has been studied spectrophotometrically. The reactions are rapid initially, then follow a second order rate dependence with respect to each of the catalyst and the oxidant. The second order rate dependence with respect to ruthenium(III) was observed for the first time. The order in [Aminoalcohol] and [OH−] is unity in each case. A suitable mechanism, consistent with the observed kinetic data is postulated.

Interaction of Polyacrylamide with Conventional Anionic and Gemini Anionic Surfactants

The interaction of polyacrylamide (PAM) with conventional anionic (sodium lauryl sulphate, NaLS) and gemini anionic (sodium salt of bis(1-dodecenyl succinimic acid), represented as NaBDS) surfactants has been studied in alkaline medium by electrical conductance and surface-tension measurements at 350C in order to compare the behavior of two surfactants toward the polymer. The surface parameters and thermodynamic parameters have been evaluated and compared. The results indicate more readily interaction of anionic gemini surfactant with the polymer (PAM).

Interaction of Quercus Infectoria Natural Dye with Cationic and Anionic Surfactants: Adsorption/Micellization of Dye

The interaction of Indian natural dye, that is, Himalaya (Quercus infectoria) with cationic surfactant (cetyl trimethyl ammonium bromide) and anionic surfactant (sodium lauryl sulphate) has been studied. The spectrophotometric data showed an interaction between the natural dye and surfactants. Critical micelle concentration (CMC) of the surfactants, determined by measurement of specific conductance and surface tension methods, was found to be increase in case of anionic surfactant while that was found to decrease in case of cationic surfactant. Thermodynamic and surface parameters showed domination of micellization of dye in case of cetyl trimethyl ammonium bromide and domination of adsorption of dye in case of sodium lauryl sulphate.

Hydrotropic Enhancement of Rate of Ninhydrin‐α‐Amino Acid Reaction: A Kinetic Study

The kinetics of ninhydrin‐α‐amino acid (alanine, phenylalanine, and valine) reaction have been studied in the absence and in the presence of a common hydrotrope, sodiumbenzoate. A strong enhancement in the rate of reaction has been observed in the presence of the hydrotrope above its minimal hydrotrope concentration (MHC). The order of reaction in ninhydrin was always found to be unity while that in amino acid decreases from unity to zero at higher [Aminoacid]. A mechanism consistent with kinetic data and involving the formation of a mixed aggregation assemblies between amino acid and hydrotrope has been proposed.

PALLADIUM(II) INHIBITION DURING CERIUM(IV) OXIDATION OF ALDOSES : A KINETIC STUDY

SummaryThe kinetics of oxidation of aldoses, namely xylose, arabinose, galactose and glucose, by CeIV have been studied in HClO4 + H2SO4 medium and in the presence of PdII. The reactions exhibit a first order rate dependence with respect to oxidant. The rate is inversely dependent on the [HSOinf4sup−]∶[H+] ratio. The order of reaction with respect to aldose decreases at higher [aldose]. Due to the formation of a complex between CeIV and PdII, a retarding effect of [PdII] on the rate of disappearance of [CeIV] has been observed. A mechanism consistent with the observed kinetic data is proposed.

Oxidation of lysine by ferricyanide in presence of osmium(VIII)

Osmium(VIII) catalysed oxidation of lysine by ferricyanide in excess ferrocyanide shows a complex kinetics. The order in lysine falls, from 1 to 0 while that in ferricyanide increases from 0 to 2 with large increase in lysine concentration. The rates were directly proportional to [Os(VIII)] and {Const.+[Fe(CN)64]}. A suitable mechanism is proposed and discussed.ZusammenfassungDie von Os(VIII) katalysierte Oxidation von Lysin mit Ferricyanid in überschüssigem Ferrocyanid zeigt eine komplexe Kinetik. Bei starker Steigerung der Lysinkonzentration fällt die Ordnung bezüglich Lysin von 1 auf 0, während bezüglich Ferricyanid eine Erhöhung, von 0 auf 2 festzustellen ist. Die Geschwindigkeitskonstanten waren direkt proportional zu [Os(VII)] und {Const.+[Fe(CN)64]}. Es wird ein möglicher Mechanismus vorgeschlagen und diskutiert.