Fast disproportionation of hexacyanomanganate(III) in acidic solution. Formation of hexacyanomanganate(IV) and kinetics of its decomposition

1986 ◽  
Vol 64 (12) ◽  
pp. 2301-2304 ◽  
Author(s):  
Guillermo López-Cueto ◽  
Carlos Ubide
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Solution ◽  
Activation Parameters ◽  
Rate Law ◽  
First Order ◽  
Experimental Rate ◽  
Parallel Pathways ◽  
Solution Formation ◽  
Kinetics Of

When potassium hexacyanomanganate(III) dissolves in acidic solution it rapidly disproportionates into hexacyanomanganate(IV) and Mn(II). Hexacyanomanganate(IV) then slowly decomposes to yield Mn(II) and (CN)2. Kinetics of the latter reaction has been studied. The reaction is found to be first order with respect to [Formula: see text], H+, and Mn(II) concentrations and the experimental rate law has the form v = kobs[Mn(IV)] = (ka + kb[H+] + kc[Mn(II)])[Mn(IV)]. At 40 °C and ionic strength 2.0, ka, kb, and kc values are (1.78 ± 0.01) × 10−4 s−1, (5.97 ± 0.05) × 10−5 s−1 M−1, and (3.40 ± 0.18) × 10−3 s−1 M−1, respectively. A mechanism with three parallel pathways is proposed, the deduced rate law being similar to the experimental one. Activation parameters, ΔH≠and ΔS≠ for the rate constants ka, kb, and kc are also reported.

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

Kinetics of iron(III) hydrolysis and precipitation in aqueous glycine solutions assessed by voltammetry

2009 ◽  
Vol 74 (10) ◽  
pp. 1531-1542 ◽  
Author(s):  
Vlado Cuculić ◽  
Ivanka Pižeta
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Rate Constants ◽  
Glycine Concentration ◽  
First Order ◽  
Mercury Drop Electrode ◽  
Calculated Rate ◽  
Cathodic Voltammetry ◽  
Kinetics Of ◽  
Voltammetric Measurements

The kinetics of iron(III) hydrolysis and precipitation in aqueous glycine solutions were studied by cathodic voltammetry with a mercury drop electrode. The kinetics was controlled by changing ionic strength (I), pH and glycine concentration. Voltammetric measurements clearly showed formation and dissociation of a soluble Fe(III)–glycine complex, formation of iron(III) hydroxide and its precipitation. The rate constants of iron(III) hydroxide precipitation were assessed. The precipitation is first-order with respect to dissolved inorganic iron(III). The calculated rate constants of iron(III) precipitation varied from 0.18 × 10–5 s–1 (at 0.2 M total glycine, pH 7.30, I = 0.6 mol dm–3) to 2.22 × 10–3 s–1 (at 0.1 M total glycine, pH 7.30, I = 0.2 mol dm–3). At 0.5 M total glycine and I = 0.6 mol dm–3, the iron(III) precipitation was not observed.

Kinetics of oxidation of cis-bis(ethylenediamine)isothiocyanatonitrocobalt(III) ion with peroxodisulphate

1979 ◽  
Vol 44 (12) ◽  
pp. 3588-3594 ◽  
Author(s):  
Vladislav Holba ◽  
Olga Volárová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Oxidation Kinetics ◽  
Reaction Rate ◽  
Salt Effect ◽  
Activation Parameters ◽  
Reaction Products ◽  
Kinetics Of Oxidation ◽  
Thermodynamic Activation Parameters ◽  
Kinetics Of

The oxidation kinetics of cis-bis(ethylenediamine)isothiocyanonitrocobalt(III) ion with peroxodisulphate was investigated in the medium of 0.01 M-HClO4 in dependence on the ionic strength and temperature and the reaction products were identified. Extrapolated values of thermodynamic activation parameters were determined from the temperature dependence of the rate constants extrapolated to zero ionic strength. The distance of the closest approach was estimated for the reacting ions by evaluating the primary salt effect. To elucidate the mechanism, the influence of the cyclic polyether 18-crown-6 on the reaction rate was followed.

Kinetics and mechanism of aminolysis of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones

1992 ◽  
Vol 70 (10) ◽  
pp. 2515-2519 ◽  
Author(s):  
Sharifa S. Alkaabi ◽  
Ahmad S. Shawali
Keyword(s):  
Rate Constants ◽  
Activation Parameters ◽  
Order Conditions ◽  
Kinetics And Mechanism ◽  
Hammett Equation ◽  
Third Order ◽  
First Order ◽  
Different Temperatures ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of the reactions of a series of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones 1 with n-butylamine and piperidine were studied spectrophotometrically in dioxane, ethanol, and cyclohexane under pseudo-first-order conditions and at different temperatures. The relation k1(obs) = k2[amine] + k3[amine]2 was found applicable for all reactions studied in either dioxane or ethanol. However, in cyclohexane the n-butylaminolysis of 1 followed only third-order kinetics k1(obs) = k3[n-BuNH2]2. The kinetics of the reaction of 1 with n-butylamine in the presence of catalytic amounts of triethylamine in dioxane followed the equation: k1(obs)k2 = [n-BuNH2] + k3[n-BuNH2]2[Formula: see text] [Et3N]. The rate constants k2 and k3 correlated well with the Hammett equation and the corresponding activation parameters were determined. The results were interpreted in terms of a mechanism involving solvent- and amine-catalyzed processes.

Kinetics and mechanism of dehydrochlorination of N-aryl-C-ethoxycarbonylformohydrazidoyl chlorides

1986 ◽  
Vol 64 (5) ◽  
pp. 871-875 ◽  
Author(s):  
Ahmad S. Shawali ◽  
Hassan A. Albar
Keyword(s):  
Rate Constants ◽  
Water Solution ◽  
Chloride Ion ◽  
Order Conditions ◽  
Rate Law ◽  
First Order ◽  
Rate Determining Step ◽  
Pseudo First Order ◽  
Reaction Constants ◽  
Kinetics Of

The kinetics of triethylamine (TEA) catalyzed deydrochlorination of a series of N-aryl-C-ethoxycarbonylformohydrazidoyl chlorides 1a–m have been studied under pseudo-first-order conditions in 4:1 (v/v) dioxane–water solution at 30 °C. For all compounds studied, the kinetics followed the rate law: kobs = k2 (TEA). The values of the overall second-order rate constants for the studied compounds were correlated by the equation: log k2 = 0.533σ−-0.218. The results are compatible with a mechanism involving a fast reversible deprotonation step leading to the anion of 1, followed by rate-determining step involving the loss of the chloride ion from the anion. The reaction constants of these two steps were estimated to be 0.845 and −0.312, respectively.

Kinetics and mechanism of the oxidation of proline by periodate

1989 ◽  
Vol 67 (4) ◽  
pp. 634-638 ◽  
Author(s):  
Rosa Pascual ◽  
Miguel A. Herraez ◽  
Emilio Calle.
Keyword(s):  
Amino Acid ◽  
Rate Constants ◽  
Reaction Rate ◽  
Ph Dependence ◽  
Kinetics And Mechanism ◽  
Appreciable Amount ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of proline by periodate has been studied at pH 1.40–8.83 and 30.0 °C. The reaction rate is first order in both periodate and amino acid, and the overall reaction follows second-order kinetics. There was no evidence for the formation of an appreciable amount of intermediate. The reaction rate is highest at pH 4–7 and the oxidation is catalysed by [Formula: see text] ions. The pH dependence of the reaction rate can be explained in terms of reaction of periodate monoanion and the protonated and dipolar forms of the amino acid. The mechanism proposed and the derived rate law are consistent with the observed kinetics. The rate constants obtained from the derived rate law are in agreement with the observed rate constants, thus justifying the rate law and the proposed mechanistic scheme. Keywords: oxidation of proline, oxidation by periodate.

Oxidation kinetics of trans-aqua-bis(ethylenediamine)-isothiocyanatocobalt(III) ion with peroxodisulphate

1979 ◽  
Vol 44 (4) ◽  
pp. 1052-1059 ◽  
Author(s):  
Olga Volárová ◽  
Vladislav Holba
Keyword(s):  
Ionic Strength ◽  
Temperature Dependence ◽  
Rate Constants ◽  
Oxidation Kinetics ◽  
Salt Effect ◽  
Activation Parameters ◽  
Thermodynamic Activation Parameters ◽  
Ionic Reactions ◽  
Kinetics Of

Oxidation kinetics of trans-aqua-bis(ethylenediamine)cobalt(III) ion with peroxodisulphate have been investigated in 0.01M-HClO4 medium within the ionic strength and temperature intervals 0.0411 to 0.4415M and 315.5 to 336.9 K, respectively. From the temperature dependence of the rate constants extrapolated to zero ionic strength the extrapolated values of thermodynamic activation parameters have been calculated. The data obtained by investigation of the primary salt effect have been confronted with relations valid for ionic reactions.

scholarly journals Kinetic Isotope Effects in the Chromium(VI) Oxidation of Bicyclic Alcohols

1999 ◽  
Vol 23 (2) ◽  
pp. 146-147
Author(s):  
J. Hodge Markgraf ◽  
Jordan S. Dubow ◽  
Jessica A. Charland ◽  
Elliott H. Sohn
Keyword(s):  
Rate Constants ◽  
Acidic Solution ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Kinetic Isotope Effects ◽  
Secondary Alcohols ◽  
First Order ◽  
Chromium Vi ◽  
Kinetic Isotope ◽  
Pseudo First Order

Pseudo first-order rate constants are determined for the oxidation of a series of secondary alcohols and their monodeutero analogues by ammonium chromate in aqueous acidic solution at several temperatures; the relative rates and activation parameters are consistent with a cyclic, symmetrical transition state.

The mechanism of the oxidative deamination and decarboxylation of serine and threonine by periodate in acid medium

1985 ◽  
Vol 63 (9) ◽  
pp. 2349-2353 ◽  
Author(s):  
Rosa Pascual ◽  
Miguel A. Herráez
Keyword(s):  
Amino Acid ◽  
Acid Medium ◽  
Rate Constants ◽  
Reaction Rate ◽  
Oxidative Deamination ◽  
Experimental Conditions ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of serine and threonine by periodate have been investigated in acid medium at 10 °C. The reaction rate is first order in both periodate and amino acid, and the overall reaction follows second-order kinetics. The rates decrease with increase in [H+]. A catalytic effect of the buffers was not observed in the oxidation process. An analysis of the dependence of the rate on [H+] reveals that the reactive species under the experimental conditions are periodate monoanion and dianion and the dipolar form of the amino acid. The mechanism proposed and the derived rate law are consistent with the observed kinetics. The rate constants predicted using the derived rate law are in agreement with the observed rate constants, thus justifying this rate law and hence the proposed mechanistic scheme.

scholarly journals Kinetics of hydride transfer between nitrogen heteroaromatic cations

1988 ◽  
Vol 66 (10) ◽  
pp. 2524-2531 ◽  
Author(s):  
John W. Bunting ◽  
Mark A. Luscher
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Hydride Transfer ◽  
First Order ◽  
Order Rate ◽  
Rate Determining Step ◽  
Donor And Acceptor ◽  
Pseudo First Order ◽  
Saturation Effects ◽  
Kinetics Of

The kinetics of the reduction of the 3-cyano-1-methylquinolinium, 4-cyano-2-methylisoquinolinium, and 2-methyl-5-nitro-isoquinolinium cations by 9,10-dihydro-10-methylacridine, and also the reduction of these same three cations as well as the 10-methylacridinium cation by 5,6-dihydro-5-methylphenanthridine, have been investigated in 20% acetonitrile – 80% water, ionic strength 1.0, 25 °C. The reactions of the 2-methyl-5-nitroisoquinolinium cation with both reductants, and also of the 4-cyano-2-methylisoquinolinium cation with 9,10-dihydro-10-methylacridine, display kinetic saturation effects in the pseudo-first-order rate constants as a function of heterocyclic cation concentration. These effects are consistent with the formation of 1:1 association complexes between hydride donor and acceptor prior to the rate-determining step of the reduction. The second-order rate constants for these reactions, and also those for analogous heterocyclic cation reductions by 1,4-dihydronicotinamides, show systematic variations as a function of the hydride donor and acceptor species.

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