Alkaline Hexacyanoferrate Research Articles

Synthesis of keto-biomacromolecule derivatives by oxidation of carboxymethyl cellulose using alkaline hexacyanoferrate (III) for alternative applications in biotechnology

The oxidation kinetics of polysaccharides involving carboxymethyl cellulose (CMC) by several oxidizing agent have been investigated in more detail with shedding some light on the synthesis of their respective keto-derivatives as oxidation precursor products. However, the literature survey indicated that no reports have appeared on the oxidation kinetics of CMC or the synthesis of keto-CMC using hexacyanoferrate (III) ion. Therefore, a lack of information on the transfer of electron process in the rate-determining stage as well as the nature of such keto-derivatives obtained as a result of polysaccharides oxidation using various oxidants in aqueous solutions.Accordingly, the present study presents synthesis of diketo CMC as a biomacromolecule derivative using potassium ferricyanide in alkaline media. The experimental results revealed the formation of either monoketo or diketo-derivatives of CMC based on initial molar ratio between the two reactants. The formation of such keto derivatives was confirmed by the reaction of the oxidation products with both 2,4-dinitrophenyl hydrazine and hydroxyl amine as well as FTIR spectra. The reaction kinetics of oxidation showed unity order in [Fe(CN)63−] and fractional first-orders with respect to both [CMC] and [OH−].The obedience of the reaction behavior to the Michael-Menten kinetics was indicative to the formation of 1:1 intermediate complex prior to the rate-determining step as a pathway route for oxidation.

Degradation of Ampicillin and Flucloxacillin Antibiotics via Oxidation by Alkaline Hexacyanoferrate(III): Kinetics and Mechanistic Aspects

The kinetics and mechanistic aspects of the oxidation of two beta-lactam antibiotics (A), ampicillin and flucloxacillin, by alkaline hexacyanoferrate(III) (HCF(III)) were examined using spectrophot...

A promising methyl ester of pectic acid polysaccharide in biomedicine and pharmaceutics applications: Oxidation of methyl ester of pectic acid by alkaline hexacyanoferrate(III). A kinetic and mechanistic orientation

AbstractThe oxidation of methyl ester of pectic acid (pectin) (PEC) by a hexacyanoferrate(III) ion at a constant ionic strength of 0.1 mol dm−3 has been investigated spectrophotometrically. The oxidation rates were found to increase with increasing the alkali concentration, indicating that the nature of reaction was base catalyzed. The agreement of [pectin] dependence of the rate constants to the Michaelis‐Menten kinetics proves the formation of 1:1 intermediate complex prior to the rate‐determining step. The deviation of the pseudo–first‐order curves from linearity after 65‐70% of reaction completion indicates the interference of some oxidation products during the reaction progression. The oxidation process was proceeding via a free‐radical intervention mechanism. The activation parameters have been evaluated, and a suitable reaction mechanism is suggested and discussed.

Base-catalyzed oxidation of sulfated kappa‑carrageenan by alkaline hexacyanoferrate(III): A mechanistic approach of electron-transfer process

The oxidation of kappa‑carrageenan (KCAR) as sulfated anionic polyelectrolyte by alkaline hexacyanoferrate(III) has been investigated spectrophotometrically. Pseudo-first-order plots showed complex kinetics where slightly upward curvatures at the initial absorbance changes were appeared, followed by linearity portions for about two-half-lives of reaction completion, and then it deviates from linearity at longer time periods. The oxidation process was found to be of base-catalyzed and free-radical intervention nature. Formation of 1:1 intermediate complex was revealed kinetically. Addition of [Fe(CN)6]4− to the reaction mixtures was found to inhibit the reaction rates. The activation parameters have been evaluated and a tentative reaction mechanism consistent with the kinetic results is suggested and discussed.

A Study of the Kinetics and Mechanism of Oxidation of Fluorene by Alkaline Hexacyanoferrate(III)

Kinetics of hexacyanoferrate (III) (HCF) oxidation of fluorene (Fl) in organic alkaline medium has been studied by spectrophotometric technique at a constant ionic strength of 0.15 mol dm-3 and at a temperature of 25°C. The reaction showed a first order kinetics with respect to [HCF] and fractional-first order dependences on both [Fl] and [OH-]. The oxidation rate was increased with the increase in the ionic strength of the reaction medium. The oxidation mechanism was suggested which involves formation of a 1:1 intermediate complex between fluorene and HCF species in a pre-equilibrium step. The final oxidation product of fluorene was identified by spectroscopic and chemical tools as 9H-fluorenone. The appropriate rate law expression was deduced and the reaction constants involved in the mechanism were evaluated. The activation parameters of the rate constant of the slow step along with the thermodynamic quantities of the equilibrium constants were evaluated and discussed.

A Mechanistic Approach to the Influence of Surfactants on the Oxidation of Ethyl Mercaptan and its Dimer Ethyl Mercaptan Disulfide by Hexacyanoferrate(III) Ions in Aqueous Medium

Abstract In this paper we report on the rate of oxidation of ethyl mercaptan and its dimer ethyl mercaptan disulfide by alkaline hexacyanoferrate(III) along with its mechanistic pathway, spectrophotometrically. The influence of different experimental parameters, such as change in concentration of EtSH, HCF, OH− and reaction temperature was studdie. It was observed that the order of reaction decreases in [EtSH] or [OH−] from first order to higher concentration, but it certainly did not tend towards zero order. The effect of surfactants on the rate of reaction was observed at the critical micelle concentration (CMC) of the surfactant and reported to be below the CMC. The investigators, thus, concluded that the added products have an insignificant effect on the reaction rate. Further, the activation parameters were evaluated which lend support to the proposed mechanism. The thermodynamic quantities were also determined and the binding parameters have also been evaluated using the Menger and Portnoy model.

Effect of Silver(I) Catalyst on the Oxidation of L-asparagine by Alkaline Hexacyanoferrate(III): A Kinetic and Mechanistic Approach

The kinetics of oxidation of L-asparagine (Asn) by hexacyanoferrate(III) (HCF) has been investigated in alkaline medium in the absence and presence of silver(I) catalyst at a constant ionic strength of 0.5 mol dm−3 and at 20°C. The progress of both uncatalyzed and silver(I)-catalyzed oxidations was followed spectrophotometrically. Both reactions showed a first order dependence with respect to [HCF], whereas the orders with respect to [Asn] and [OH−] were less than unity. The catalyzed reaction exhibited a first order dependence in [AgI]. Increasing both ionic strength and dielectric constant of the reaction medium increased the rate of uncatalyzed reaction and did not affect significantly the rate of catalyzed reaction. Addition of the reaction product, HCF(II) to the reaction mixture had no affect on the rate. Appropriate reaction mechanisms for both uncatalyzed and catalyzed oxidations explaining all of the observed kinetic results has been proposed. The catalyzed reaction has been shown to proceed via formation of a silver(I)-asparagine intermediate complex, which reacted with the oxidant by an inner-sphere mechanism leading to decomposition of the complex in the rate-determining step to yield the final oxidation products which were identified as α-formyl acetamide, ammonia, and carbon dioxide. The rate law expressions associated with the reaction mechanisms were derived.

Kinetic and Mechanism of Oxidation of Methylaminopyrazole Formamidine by Alkaline Hexacyanoferrate(III) and the Effect of Divalent Transition Metal Ions

In aqueous alkaline medium, the kinetics of oxidation of methylaminopyrazole formamidine (MAPF) by hexacyanoferrate(III) (HCF)has been studied spectrophotometrically under the conditions, MAPF >> HCF at a constant ionic strength of 0.1 mol dm-3 and at 25°C. The reaction showed first order dependence on [HCF] while it exhibited fractional-first order kinetics with respect to [MAPF] and [OH-]. The oxidation rate increased with increasing ionic strength and dielectric constant of the reaction medium. Addition of small amounts of some divalent transition metal ions accelerates the oxidation rate and the order of catalytic efficiency was: Cu(II) > Ni(II) > Zn(II) > Co(II) > Cd(II). The suggested mechanism involves formation of a 1: 1 intermediate complex between HCF and the deprotonated MAPF species in a pre-equilibrium step. The final oxidation products were identified as methylaminopyrazole, dimethylamine and carbon dioxide. The appropriate rate law was deduced. The reaction constants involved in the mechanism were evaluated. The activation and thermodynamic parameters were determined and discussed.

Investigation of electron-transfer reaction between alkaline hexacyanoferrate(III) and ranitidine hydrochloride – a histamine H2 receptor antagonist, in the presence of homogenous ruthenium(III) catalyst

The ruthenium(III)-catalyzed electron-transfer reaction between hexacyanoferrate(III) and ranitidine hydrochloride is studied in alkaline medium at 25°C and at an ionic strength of 1.10 mol/dm3. The reaction stoichiometry is established and is found to be 1:4, that is, for the oxidation of one mole of ranitidine, four moles of hexacyanoferrate(III) are consumed. The reaction products were characterized by spectral studies such as IR, GC-MS, 1H-NMR and 13C-NMR. The reaction rate shows a less than unit order in substrate and alkali and a first-order dependence in oxidant, [Fe(CN)6]3− and the catalyst, ruthenium(III) concentrations. The active species of ruthenium(III), [Ru(H2O)5OH]2+, forms an intermediate complex with the substrate. The attack of complex by hexacyanoferrate(III) in the rate determining step produces a radical cation, which is further oxidized in the subsequent step to form the oxidation product. The effect of the reaction environment on the rate constant upon adding varying concentrations of KNO3 and t-butanol was studied. The initially added products did not have any significant effect on the reaction rate. A plausible mechanism is proposed based on the experimental results. The effect of varying temperature on the reaction rate was also studied. The activation parameters for the slow step and the thermodynamic quantities for the equilibrium steps were evaluated.The mechanism of title reaction has been studied and one mole of ranitidine consumes four moles of [Fe(CN)6]3−, as shown in the following equation:

Kinetics and Mechanism of Electron Transfer Reaction: Osmium (VIII) and Ruthenium (III) Catalyzed Oxidation of Sulfanilic Acid by Alkaline Hexacyanoferrate (III)

Kinetics and Mechanism of Electron Transfer Reaction: Osmium (VIII) and Ruthenium (III) Catalyzed Oxidation of Sulfanilic Acid by Alkaline Hexacyanoferrate (III)

Kinetics and Mechanistic Study of Oxidation of Ethyl Vanillin by Alkaline Hexacyanoferrate(III)

Kinetics and Mechanistic Study of Oxidation of Ethyl Vanillin by Alkaline Hexacyanoferrate(III)

Base-catalyzed oxidation of some anionic polyelectrolytes: Kinetic and mechanistic aspects to electron-transfer process into hexacyanoferrate(III) oxidation of alginate polysaccharide in alkaline media

The kinetics and mechanism of oxidation of alginate polysaccharide (Alg) by alkaline hexacyanoferrate(III) in basic solutions at a constant ionic strength of 1.0moldm−3 have been investigated spectrophotometrically. The experimental results showed complex kinetics, where the reaction time curves of the pseudo first-order plots were found to be of sigmoidal S-shape nature. The initial parts of the plots were relatively fast, followed by slow-linear portions after short time periods. The oxidation rates were increased with increasing the alkali concentration indicating that the oxidation is base-catalyzed. A kinetic evidence for formation of 1:1 intermediate complexes was revealed. The activation parameters have been evaluated and a tentative reaction mechanism consistent with the kinetic results is suggested and discussed.

Kinetics and mechanism of iridium(III) catalysed oxidation of DL-methionine by alkaline hexacyanoferrate(III)

Kinetics and mechanism of iridium(III) catalysed oxidation of DL-methionine by alkaline hexacyanoferrate(III)

Kinetics and Mechanism of Oxidation of D-Penicillamine by Potassium Hexacyanoferrate(III) Ions in Aqueous Solution in the Presence of Sodium Dodecyl Sulphate and Cetyltrimethylammonium Bromide

The effect of cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulphate (SDS) on the rate of oxidation of D-penicillamine by alkaline hexacyanoferrate(III) has been studied by spectrophotometrically at different temperatures. The effect of CTAB and SDS on the rate of reaction has been observed at even below the critical micelle concentration (CMC) of the surfactants, indicating binding of the substrate with the surfactants. On the basis of the kinetic results, the mechanism of the reaction has been proposed. The kinetic data have been rationalized in terms of Manger and Portnoy's model for micellar inhibition and binding parameters (viz. binding constants, partition coefficient, free energy transfer from water to micelle, etc.); activation parameters have also been evaluated.

Mechanistic studies of ruthenium(III)-catalyzed oxidation of DL-methionine by hexacyanoferrate(III) in an alkaline medium

The kinetics and mechanism of ruthenium(III) catalyzed oxidation of dl-methionine by alkaline hexacyanoferrate(III) (HCF(III)) in an alkaline medium were studied spectrophotometrically at 30±0.1°C. The reaction was first-order-dependent each on [HCF(III)] and [ruthenium(III)] and fractional-order-dependent on [alkali]. The rate of the reaction was found to be decreased with the increase in [methionine]. The main product of oxidation was methionine sulfone nitrile (3-(methylsulfonyl)propanenitrile) and it was identified and confirmed by FT-IR and mass spectral studies. Further, no effect of added reaction product was observed. A plausible mechanism was proposed involving complexation between methionine and ruthenium(III) species, [Ru(H2O)5OH]2+. Thermodynamic parameters for the reaction, E a and Δ S #, were computed using linear least squares method and are found to be 65.83±1.03 kJ/mol and−249.58±3.35 J/K mol, respectively.

Mechanism of the Osmium(Viii)-Catalysed Oxidation of Fursemide by Alkaline Hexacyanoferrate(Iii) and Analysis of Fursemide by a Kinetic and Catalytic Method

The kinetics of the title reaction showed first-order behaviour both in hexacyanoferrate(III) and osmium(VIII) and fractional order each in fursemide and alkali concentrations. The added product, [Fe(CN)6]4-, retarded the rate of reaction. The active species of osmium(VIII) in alkali appears to be [OsO5(OH)]3-. A mechanism involving a complex formed between osmium(VIII) and fursemide, followed by its oxidation with hexacyanoferrate(III) in a rate-determining step is proposed. A rate law for the mechanism was derived and verified. The formation constant, K2 for [OsO5(OH)]3-, K3 for the complex, and the rate constant of the slow step, k, were evaluated. The activation parameters Ea, Δ H#, Δ S#, Δ G# and log A were calculated as 55.2 ± 2kJ mol−1, 52.7 ± 2 kJ mol−1, - 52.0 ± 2 JK−1 mol−1, 69.8 ± 2.5 kJ mol−1 and 6.5 ± 0.1 respectively. Fursemide is used in the pharmacotherapy for various diseases and it is also considered as a doping agent in sports. A simple and specific procedure for its analysis was developed being based on its oxidation by alkaline hexacyanoferrate(III) in the presence of trace amount of osmium(VIII) catalyst. Three different methods have been recommended, namely, the rate constant method, fixed time method and fixed change in optical density method. of these, the latter two were found to be fast, simple, and accurate. from these methods, fursemide could be analysed from a few micrograms to milligrams per cm3. The interference by binders of tablets, and other possible substances like proteins and amino acids, have also been studied.

Hexacyanoferrate(III) oxidation of arsenic and its subsequent removal from the spent reaction mixture

Inorganic arsenic is the most toxic form and has been classified in group 1 as carcinogenic to humans which induces lung, urinary bladder and primary skin cancer. Worldwide concern over its presence in water bodies have prompted much research and policy development focusing on the removal of this chronic human carcinogen. It has been observed that the ash of Unio ( Lamellidens marginalis – the fresh water mussel) can be used successfully for the removal of arsenic(V) from the aqueous solutions at low pH (∼9.0). Initially the kinetics of oxidation of arsenic(III) by alkaline hexacyanoferrate(III), both with and without adding iridium(III) chloride was studied. Subsequently after complete removal of ferrocyanide, the removal of arsenic(V) produced in the spent reaction mixture was taken up. Out of the five ashes obtained from different sources, the ash of Unio was found to be the best which results in decreasing arsenic(V) concentration from 1000 ppb to >10 ppb, TDS from 16.9 ppt to 8.5 ppt and conductivity from 33.8 mS to 17.1 mS. Kinetic results show the possibility of graphical separation of the reaction proceeding in the absence of iridium(III) from that proceeding in the presence of iridium(III) chloride.

Alcohol oxidation catalysed by Ru(VI) in the presence of alkaline hexacyanoferrate(III)

AbstractThe oxidation of sodium lactate, 2‐methyl‐2,4‐pentanediol, 2,4‐butanediol, 2‐butanol and 2‐propanol upon treatment with alkaline hexacyanoferrate(III) using a Ru(VI) catalyst is highly effective for the oxidation of alcohols by ${\rm Fe}({\rm CN})_{6}^{3{-} }$. The reaction mechanism proposed involves the oxidation of the alcohol by the catalyst, a process that occurs through the formation of a substrate‐catalyst complex. The decomposition of this complex yields Ru(IV) and a carbocation (owing to a hydride transfer from the α‐CH bond of the alcohol to the oxoligand of ruthenium). The role of the co‐oxidant, hexacyanoferrate(III), is to regenerate the catalyst. In the oxidation reactions, the rate constants for complex decomposition and catalyst regeneration have been determined and a comparative study of the structure versus reactivity has been carried out. Copyright © 2010 John Wiley & Sons, Ltd.

Kinetics, mechanism and thermodynamic studies of rhodium(III) catalysed oxidation of alanine by alkaline hexacyanoferrate(III)

The kinetics and mechanism of rhodium(III) catalysed oxidation of alanine in alkaline solution of hexacyanoferrate(III) have been studied. The kinetic data shows zero order dependence on each hexacyanoferrate(III) and sodium hydroxide whereas first order dependence each on alanine and Rh III . Negligible effect of ionic strength of the medium has been reported. A suitable mechanism consistant with the observed kinetics has been suggested.

Oxidation of cyclic ketones by alkaline hexacyanoferrate(III) catalyzed by rhodium(III)

The kinetics of the reaction between cyclopentanone and cyclohexanone with hexacyanoferrate(III) ion catalyzed by rhodium(III) chloride in alkaline medium has been investigated at four temperatures. The data show that the reaction follows first order kinetics with respect to hydroxide ion and cyclic ketone concentrations while the rate shows direct proportionality with respect to low concentrations of hexacyanoferrate(III) ion, which tends to become zeroth order at higher [oxidant]. Increase in rhodium(III) chloride concentrations increases the rate in the beginning but after reaching to a maximum further increase in catalyst concentration retards the rate, thus showing a peculiar nature. In both cases, decrease in rate after a fixed maximum is attributed to a particular pH of the medium below which un-reactive species of catalyst retards the velocity. Change in pH of the medium shows that decreasing pH decreases the rate with breaks at specific points. Increase in ionic strength of the medium has a positive effect, while increase in hexacyanoferrate(II) decreases the reaction velocity. Various thermodynamic parameters were calculated.