Kinetics of Oxidation of Ferrocyanide by lodate Ion

1974 ◽  
Vol 52 (11) ◽  
pp. 2001-2004 ◽  
Author(s):  
Y. Sulfab ◽  
Hamid A. Elfaki
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Formation Constant ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
Ph Range ◽  
Kinetics Of ◽  
Rate Determining Steps

In the presence of vast excess of ferrocyanide, over the pH range 1.76–2.65, the reaction between iodate and ferrocyanide ions follows the rate law[Formula: see text]where ka and kb have values of 1.97 × 103 M−2 min−1 and 4.08 × 105 M−3 min−1, respectively, at an ionic strength of 1.18 M and a temperature of 25.0 ± 0.1 °C. K1 is the formation constant of monoprotonated ferrocyanide. The "overall activation energy" of the reaction was found to be 15.8 kcal/mol. Rate-determining steps consistent with the kinetics have been proposed.

Kinetics of oxidation of thiocyanate by aqueous iodine

1973 ◽  
Vol 26 (9) ◽  
pp. 1863 ◽  
Author(s):  
GT Briot ◽  
RH Smith
Keyword(s):  
Rate Constants ◽  
Activation Energies ◽  
Stopped Flow ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
General Base ◽  
Present Rate ◽  
Rapid Equilibrium ◽  
Ph Range ◽  
Kinetics Of

The kinetics of oxidation of thiocyanate to sulphate by aqueous iodine in the pH range 9.2-12.5 have been studied using a spectrophotometric stopped flow technique. The reaction is general base-catalysed, having the rate law ��������������������� -d[I2]a/dt = ([SCN-][I3-]/[I-]2)Σ kB[B] where [I2]a is the total analytical concentration of iodine, [B] is the concentration of base, and where the summation is taken over all bases present. Rate constants, kB, and activation energies have been measured for the bases, OH-, PO43- and CO32-. ��� A mechanism involving the initial steps ����������������� I2+SCN- ↔ ISCN+I- �����������������(rapid equilibrium) ������������� ISCN+H2O+B → HOSCN+I- + HB+ �����������(rate determining) followed by rapid reactions of HOSCN with itself or with iodine is proposed.

Kinetics of oxidation of nitrite by hypochlorite ions in aqueous basic solution

1976 ◽  
Vol 54 (21) ◽  
pp. 3401-3406 ◽  
Author(s):  
J. M. Cachaza ◽  
J. Casado ◽  
A. Castro ◽  
M. A. López Quintela
Keyword(s):  
Ionic Strength ◽  
Initial Step ◽  
Activation Energies ◽  
The Other ◽  
Basic Solution ◽  
Unimolecular Decomposition ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
Kinetics Of

The kinetics of oxidation of nitrite to nitrate by hypochlorite ions in aqueous basic solution [Formula: see text] have been studied using a dynamic spectrophotometric technique. The rate law is[Formula: see text]At 298.0 K and ionic strength 0.40 M, d = (3.4 ± 0.2) × 10−8 mol l−1 s−1 and e = (2.8 ± 0.2) × 10−6 s−1. The associated activation energies are 56 ± 3 and 61 ± 3 kJ mol−1 respectively. A mechanism is proposed involving the reversible initial step:[Formula: see text]with the NO2Cl undergoing two parallel subsequent reactions, one a unimolecular decomposition and the other an attack by NO2− on NO2Cl.

Kinetics of oxidation of nitrite by aqueous bromine

1973 ◽  
Vol 26 (9) ◽  
pp. 1847 ◽  
Author(s):  
JN Pendlebury ◽  
RH Smith
Keyword(s):  
Perchloric Acid ◽  
Acetate Buffer ◽  
Stopped Flow ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
Rate Laws ◽  
Temperature Dependences ◽  
Ph Range ◽  
Kinetics Of

The kinetics of oxidation of nitrite to nitrate by aqueous bromine have been investigated using a spectrophotometric stopped flow technique. In the pH range 4.2-5.8 (acetate buffer) the rate law is: - d[Br21,/dt = [Br21[N02 -I2 (a + b/[Br-1) (where [Br,], = [Br2]+[Br,-1) with a = (4.61-0-1) x lo4 l2 m01-~ s-l and b = (3.3 1-0.1) x lo4 1. mol-l s-l at 298.2 K and with the temperature dependences, - R d(lna)/d(l/T) = (46k 4) kJ mol-l and - R d(ln b)/d(l/T) = (45 k 2) kJ mol-'. In the pH range 0.8-2.5 (perchloric acid) the rate law is : - d[Br2],/dt = [HN0212[Br21 (w + v/[Br-l)/(l+ z[H+ItBr,l,) with w = (5.9+0.2)x lo4 l2 m01-~ s-l, v = (3.41-0.1)~ lo4 1, mol-l s-I, and z = (1.90i 0.06) x lo7 l2 mol-2 at 298.2 K. In addition: - R d ln(w/z)/d(l/T) = (31 1 4 ) kJ mol-I and - R d ln(v/z)/d(l/T) = (46 f 4) kJ mol-l In the pH range 2.8-3.3 (chloroacetate buffer) a combination of these two rate laws adequately describes the kinetic results. These rate laws have been interpreted in terms of two reversible initial reactions: 6) NO2- +Br2 + N02Br +Br- (followed by attack on N02Br by NO2-) (ii) NO2-+NO2- (or HNOJ + N204'- (or HN204-) (followed by attack by Br2 upon N204'- or HNZO4- or upon N203 formed from HN204-).

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.

A Study of Substituent Effect on the Oxidative Strengths of N-Chloroarenesulphonamides: Kinetics of Oxidation of Leucine and Isoleucine in Aqueous Acid Medium

2004 ◽  
Vol 59 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Mahesha Shetty ◽  
B. Thimme Gowda
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ionic Strength ◽  
Acid Medium ◽  
Benzene Ring ◽  
Thermodynamic Data ◽  
Substituent Effect ◽  
Kinetics Of Oxidation ◽  
Aqueous Acid ◽  
Kinetics Of

Abstract To study the variation of oxidative strengths of N-chloro-arenesulphonamides with substitution in the benzene ring, six mono- and five di-substituted N-chloro-arenesulphonamides are employed as oxidants for studying the kinetics of oxidation of two neutral amino acids, L-leucine and Lisoleucine in aqueous acid medium. The N-chloro-arenesulphonamides studied are of the constitution: ArSO2NaNCl·H2O (where Ar = C6H5, 4-CH3C6H4, 4-C2H5C6H4, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 2,3-(CH3)2C6H3, 2,4-(CH3)2C6H3, 2-CH3-4-ClC6H3, 2,4-Cl2C6H3, and 3,4-Cl2C6H3). The reactions show second order kinetics in [oxidant], fractional order in [amino acid] and inverse dependence on [H+]. Addition of the reduced product of the oxidants or variation in ionic strength of the medium has no significant effect on the rates of oxidations. A two-pathway mechanism is considered to explain the experimental results. Effective oxidizing species of the oxidants is Cl+ in different forms. Therefore the oxidising strengths of N-chloro-arenesulphonamides depend on the ease with which Cl+ is released from them. The study reveals that the introduction of substituent in the benzene ring of the oxidant affects both the kinetic and thermodynamic data for the oxidations The electron releasing groups such as CH3 generally inhibit the rates, while electron-withdrawing groups such as Cl enhance this ability, as the electron withdrawing groups ease the release of Cl+ from the reagents and hence increase the oxidising strengths. The on Ea and logA and validity of the Hammett and isokinetic relationships for the oxidations are also analysed.

Kinetics of the addition of acids to olefins with and without boron fluoride catalysis

1967 ◽  
Vol 45 (1) ◽  
pp. 11-16 ◽  
Author(s):  
G. A. Latrèmouille ◽  
A. M. Eastham
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Apparent Activation Energy ◽  
Trifluoroacetic Acid ◽  
Similar Rate ◽  
Ethylene Dichloride ◽  
Kcal Mole ◽  
Rate Law ◽  
Boron Fluoride ◽  
Kinetics Of

Isobutene reacts readily with excess trifluoroacetic acid in ethylene dichloride solution at ordinary temperatures to give t-butyl trifluoroacetate. The rate of the reaction is given, within the range of the experiments, by the expression d[ester]/dt = k[acid]2[olefin], and the apparent activation energy is about 6 kcal/mole. The rate of addition is markedly dependent on the strength of the reacting acid and is drastically reduced in the presence of mildly basic materials, such as dioxane. The boron fluoride catalyzed addition of acetic acid to 2-butene can be considered to follow a similar rate law, i.e. d[ester]/dt = k[acid·BF3]2[olefin], but only if some assumptions are made about the position of the equilibrium [Formula: see text]since only the 1:1 complex is reactive.

scholarly journals A study of the oxidation of butan-1-ol and propan-2-ol by nicotinamide-adenine dinucleotide catalysed by yeast alcohol dehydrogenase.

1975 ◽  
Vol 147 (3) ◽  
pp. 541-547 ◽  
Author(s):  
C J Dickenson ◽  
F M Dickinson
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ternary Complexes ◽  
Kinetics Of Oxidation ◽  
Yeast Alcohol Dehydrogenase ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Ph Range ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Flow Experiments

1. The kinetics of oxidation of butan-1-ol and propan-2-ol by NAD+, catalysed by yeast alcohol dehydrogenase, were studied at 25 degrees C from pH 5.5 to 10, and at pH 7.05 from 14 degrees to 44 degrees C, 2. Under all conditions studied the results are consistent with a mechanism whereby some dissociation of coenzyme from the active enzyme-NAD+-alcohol ternary complexes occurs, and the mechanism is therefore not strictly compulsory order. 3. A primary 2H isotopic effect on the maximum rates of oxidation of [1-2H2]butan-1-ol and [2H7]propan-2-ol was found at 25 degrees C over the pH range 5.5-10. Further, in stopped-flow experiments at pH 7.05 and 25 degrees C, there was no transient formation of NADH in the oxidation of butan-1-ol and propan-2-ol. The principal rate-limiting step in the oxidation of dependence on pH of the maximum rates of oxidation of butan-1-ol and propan-2-ol is consisten with the possibility that histidine and cysteine residues may affect or control catalysis.

KINETICS OF THE OXIDATION OF URANIUM (IV) BY IRON (III) IN AQUEOUS SOLUTIONS OF PERCHLORIC ACID

1955 ◽  
Vol 33 (12) ◽  
pp. 1780-1791 ◽  
Author(s):  
R. H. Betts
Keyword(s):  
Electron Transfer ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Perchloric Acid ◽  
Rate Constants ◽  
Kcal Mole ◽  
Kinetics Of Oxidation ◽  
Temperature Coefficients ◽  
Kinetics Of ◽  
Rate Controlling Step

The kinetics of oxidation of uranium (IV) by iron (III) in aqueous solutions of perchloric acid have been investigated at four temperatures between 3.1 °C. and 24.8 °C. The reaction was followed by measurement of the amount of ferrous ion formed. For the conditions (H+) = 0.1–1.0 M, ionic strength = 1.02, (FeIII) = 10−4–10−5 M, and (UIV) = 10−4–10−5 M, the observed rate law is d(Fe2+)/dt = −2d(UIV)/dt[Formula: see text]K1 and K2 are the first hydrolysis constants for Fe3+ and U4+, respectively, and K′ and K″ are pseudo rate constants. At 24.8 °C., K′ = 2.98 sec.−1, and K″ = 10.6 mole liter−1 sec−1. The corresponding temperature coefficients are ΔH′ = 22.5 kcal./mole and ΔH″ = 24.2 kcal./mole. The kinetics of the process are consistent with a mechanism which involves, as a rate-controlling step, electron transfer between hydrolyzed ions.

Kinetics and mechanism of disproportionation and ferricyanide oxidation of the 10-methylacridinium cation in aqueous base

1984 ◽  
Vol 62 (4) ◽  
pp. 729-735 ◽  
Author(s):  
John W. Bunting ◽  
Glenn M. Kauffman
Keyword(s):  
Ionic Strength ◽  
Second Order ◽  
Kinetics And Mechanism ◽  
Oxidation Pathway ◽  
First Order ◽  
Aqueous Base ◽  
Ph Range ◽  
Rate Profile ◽  
Kinetics Of ◽  
Major Oxidation

The kinetics of disproportionation and ferricyanide ion oxidation of the 10-methylacridinium cation have been measured spectrophotometrically over the pH range 9–14 in.20% CH3CN – 80% H2O (v/v) and ionic strength 1.0 at 25 °C. Disproportionation is kinetically second-order in total acridine species. The pH–rate profile is consistent with the rate-determining reaction of one acridinium cation with the pseudobase alkoxide anion derived from a second acridinium cation. Ferricyanide ion oxidation is kinetically first-order in each of ferricyanide ion and total acridine species. The pH–rate profile requires three distinct pathways for the ferricyanide ion oxidation of the 10-methylacridinium cation. For pH < 9.7, rate-determining attack of ferricyanide ion on the neutral pseudobase predominates, while for pH > 12.8 the predominant oxidation pathway involves reaction of ferricyanide ion with the pseudobase alkoxide ion. Between pH 9.7 and 12.8, the major oxidation pathway involves initial disproportionation of the acridinium cation followed by ferricyanide ion oxidation of the 9,10-dihydro-10-methylacridine product. This latter route accounts for a maximum of 69% of the total ferricyanide ion oxidation at pH 11.1.

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