Oxidations involving silver. I. Kinetics of the anodic oxidation of silver in alkaline electrolytes

1968 ◽  
Vol 46 (22) ◽  
pp. 3437-3442 ◽  
Author(s):  
T. G. Clarke ◽  
N. A. Hampson ◽  
J. B. Lee ◽  
J. R. Morley ◽  
B. Scanlon
Keyword(s):  
Electrochemical Oxidation ◽  
Anodic Oxidation ◽  
Kcal Mole ◽  
Kinetics Of Oxidation ◽  
Ion Concentrations ◽  
Enthalpy Of Activation ◽  
Hydroxyl Ion ◽  
Different Temperatures ◽  
Alkaline Electrolytes ◽  
Kinetics Of

The kinetics of the electrochemical oxidation of silver to Ag2O in NaOH have been studied at different temperatures and hydroxyl ion concentrations. The enthalpy of activation was found to be ~ 5 kcal/mole. The kinetics of oxidation of Ag2O to AgO are discussed.

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.

Vulcanization of Elastomers. 25. Natural Rubber and Synthetic Elastomers with Sulfur and Sulfenamides. I

1960 ◽  
Vol 33 (3) ◽  
pp. 846-856 ◽  
Author(s):  
Walter Scheele ◽  
Horst-Eckart Toussaint ◽  
Yoan-Kun Chai
Keyword(s):  
Reaction Order ◽  
Molar Ratio ◽  
Reactive Intermediate ◽  
Sulfur Concentration ◽  
Kcal Mole ◽  
Experimental Conditions ◽  
Sulfur Vulcanization ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Time Plot

Abstract The sulfur vulcanization of Perbunan N 2818 (acrylonitrile-butadiene) was investigated in the presence of N-cyclohexyl-2-benzothiazolylsulfenamide (CZ) at different temperatures and various concentrations of reactants. The following were found : 1. The decreasing sulfur concentration vs. time plot followed the 0.8th order under all experimental conditions and an activation energy of 28.2 kcal/mole was calculated. 2. When using the cyclohexylammonium salt of MBT as accelerator, sulfur decrease proceeds at the same rate as with CZ. 3. It was concluded from 1 and 2 that even in the presence of CZ, the ammonium salt was the actual accelerator, which forms during the scorch or induction period through reaction of CZ with the rubber. 4. In view of the discrepancy found in the relation of reaction order with respect to time and concentration of reactants, the formation of a reactive intermediate is postulated; the analogy between the kinetics of sulfenamide accelerated sulfur vulcanization, and those accelerated with MBT as well as DPG is pointed out. 5. In connection with 3 the dependence of starting rate as well as rate constant of 0.8th order of the decreasing sulfur concentration on the molar ratio of CZ/S8 and on the sulfur starting concentration is discussed.

scholarly journals Kinetics of Oxidation of Amino Acids by a Newly Synthesized Oxidant, N-Chloropyrazinamide in Aqueous Acetic Acid Medium

2013 ◽  
Vol 16 ◽  
pp. 1-8
Author(s):  
S. Parimala Vaijayanthi ◽  
N. Mathiyalagan
Keyword(s):  
Amino Acids ◽  
Acetic Acid ◽  
Acid Medium ◽  
Activation Parameters ◽  
Aqueous Acetic Acid ◽  
Acetic Acid Medium ◽  
Kinetics Of Oxidation ◽  
Different Temperatures ◽  
Probable Reaction ◽  
Kinetics Of

The kinetics of oxidation of amino acids namely, alanine, glycine, leucine, phenyl alanine and valine by N-chloropyrazinamide (NCPZA) in aqueous acetic acid medium in the presence of hydrochloric acid have been investigated. The observed rate of oxidation is first order in [NCPZA], [H+] and [Clˉ]. The order with respect to [amino acid] is zero. The rate of oxidation increases with increase in the percentage of acetic acid. The reaction rate increases slightly with increase in ionic strength, while retards with addition of pyrazinamide. Arrhenius and thermodynamic activation parameters have been evaluated from Arrhenius plot by studying the reaction at different temperatures. A most probable reaction mechanism has been proposed and an appropriate rate law is deduced toaccount for the observed kinetic data.

Mechanism of Hg(II) Oxidation of D-Galactose in Alkaline Medium

1978 ◽  
Vol 33 (6) ◽  
pp. 657-659 ◽  
Author(s):  
M. P. Singh ◽  
A. K. Singh ◽  
Mandhir Kumar
Keyword(s):  
Alkaline Medium ◽  
Reaction Rate ◽  
Reducing Sugar ◽  
Zero Order ◽  
Ion Concentration ◽  
Kinetics Of Oxidation ◽  
Ion Concentrations ◽  
First Order ◽  
Kinetics Of ◽  
Direct Proportionality

Abstract The present paper deals with the kinetics of oxidation of D-galactose by Nessler's reagent in alkaline medium. The reaction is zero order with respect to Hg(II) and first order with respect to reducing sugar. The direct proportionality of the reaction rate at low hydroxide ion concentrations shows retarding trend at higher concentrations. The reaction rate is inversely proportional to iodide ion concentration. A mechanism has been proposed taking HgI3- as the reacting species

scholarly journals Mechanistic Investigation of Oxidation of Phenylpropanolamine withN-Bromobenzenesulfonamide in Alkaline Medium: A Kinetic Approach

2008 ◽  
Vol 5 (2) ◽  
pp. 331-341
Author(s):  
Ningegowda Prasad ◽  
Kikkeri N. Mohana
Keyword(s):  
Alkaline Medium ◽  
Activation Parameters ◽  
Chloride Ion ◽  
Reaction Scheme ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
Conjugate Acid ◽  
Mechanistic Investigation ◽  
Different Temperatures ◽  
Kinetics Of

The kinetics of oxidation of phenylpropanolamine (PPA) with sodium N-bromobenzenesulfonamide or bromamine-B (BAB) has been investigated in alkaline medium at 308 K. The oxidation reaction obeys the rate law, – d[BAB]/dt = k [BAB] [PPA]x [OH-], where x is less than unity. The variation of ionic strength of the medium, addition of the reduction product, benzenesulfonamide, and chloride ion had no pronounced effect on the reaction rate. Decrease of dielectric permittivity of the medium by increasing the CH3CN content increased the rate. The reaction was studied at different temperatures and the activation parameters have been evaluated from the Arrhenius plot. The stiochiometry of the reaction was found to be 1:1, and the oxidation product of phenylpropanolamine was identified as benzaldehyde and ethylideneamine. The rate decreased in D2O medium and the normal isotope effect k' (H2O) / k' (D2O) is 2.18. Proton inventory studies have been made in H2O - D2O mixtures. Formation and decomposition constant of BAB-PPA complexes in the reaction scheme have been determined. The conjugate acid, C6H5SO2NHBr is assumed to be the reactive species. The proposed mechanism and the derived rate law are consistent with the observed experimental results.

Nuclear magnetic resonance study of proton exchange in the water – 2-propanol system

1970 ◽  
Vol 48 (10) ◽  
pp. 1616-1618 ◽  
Author(s):  
K. C. Tewari ◽  
N. C. Li
Keyword(s):  
Activation Energy ◽  
Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Proton Exchange ◽  
Electron Donors ◽  
Specific Rate ◽  
Kcal Mole ◽  
Magnetic Resonance Study ◽  
Different Temperatures ◽  
Kinetics Of

The specific rate constants for the reaction[Formula: see text]where ROH is 2-propanol, have been determined at four different temperatures. The activation energy has been calculated to be 10.4 kcal/mole. In addition, the effect of the presence of several electron donors on the kinetics of the reaction has been noted.

Vulcanization of Elastomers. 36. Vulcanization of Natural Rubber and Synthetic Rubbers with Sulfur in Absence of Accelerators. II

1964 ◽  
Vol 37 (4) ◽  
pp. 910-926 ◽  
Author(s):  
W. Scheele ◽  
H. Müller ◽  
W. Schulze
Keyword(s):  
Natural Rubber ◽  
Concentration Dependence ◽  
Good Description ◽  
Kcal Mole ◽  
First Order ◽  
Different Temperatures ◽  
In Cis ◽  
Kinetics Of ◽  
Limiting Value ◽  
Homolytic Dissociation

Abstract In continuation of earlier work with natural rubber, the kinetics of sulfur decrease were studied in certain synthetic rubbers for different temperatures and sulfur concentrations. At the same time the formation of polysulfide bound sulfur was studied, using as example the reaction of sulfur with natural rubber and synthetic rubbers. It was found that: 1) When the decrease in sulfur concentration is portrayed by curves which are convex to the time axis (Perbunan), the 0.6th order time-law is fulfilled, (as in the case of natural rubber independent of temperature and concentration. 2) In contrast, the concentration dependence of the rate at which sulfur decreases, both in Perbunan and cis 1,4-polybutadiene, denotes a first-order reaction in agreement with experience with natural rubber. 3) The activation energy of sulfur decrease has the same magnitude for all the elastomers investigated (34 to 36 kcal/mole). 4) The disagreement between the time law and the concentration dependence of the rate of sulfur disappearance encountered in all the experiments with 1,5-polyenes, is interpreted as indicating autocatalysis, which likewise explains the shape of the curves for sulfur disappearance. 5) Sulfur reacts considerably faster in natural rubber and Perbunan than in cis 1,4-polybutadiene; consequently a homolytic dissociation of the S8-ring cannot be rate-determining. 6) Polysulfide sulfur shows, in each case, a maximum with reaction time, and in completely reacted vulcanizates it tends toward a limiting value. An equation was found, which provides a good description of change with time of polysulfide concentration (natural rubber and cis 1,4-polybutadiene). 7) An explanation is given for the appearance of the polysulfide maximum; and how the reaction of sulfur with 1,5-polyenes can be represented, making use of all available results, is discussed.

Transition from internal to external oxidation in indium–silver alloys

1968 ◽  
Vol 46 (8) ◽  
pp. 1187-1196 ◽  
Author(s):  
L. D. Pethe ◽  
H. B. Mathur ◽  
A. B. Biswas
Keyword(s):  
Cross Sections ◽  
Absolute Temperature ◽  
Kcal Mole ◽  
Kinetics Of Oxidation ◽  
External Oxidation ◽  
Parabolic Oxidation ◽  
Parabolic Oxidation Rate ◽  
Straight Lines ◽  
Kinetics Of ◽  
Rate Controlling Step

The kinetics of oxidation of In–Ag alloys of 5,10, and 15 at. % indium have been studied on a vacuum microbalance. The 15 at. % indium alloy oxidizes externally and the 5 at. % alloy internally. A plot of logarithm of the parabolic oxidation rate, kp, versus reciprocal of the absolute temperature for 10 at. % indium alloy gives two intersecting straight lines corresponding to the energies of activation of 23 and 39.6 kcal/mole for the oxidation below and above 600 °C respectively. These are comparable to the energies of activation of 23 kcal/mole for the internal oxidation of 5 at. % indium alloy and 40 kcal/mole for the external oxidation of 15 at. % indium alloy. The rate–controlling step in the external oxidation of 15 at. % indium alloy is the diffusion of indium through the alloy. Photomicrographs of the cross sections of the oxidized foils of these alloys confirm the conclusions derived from the kinetic data.

THE CHEMISTRY OF ETHYLENE OXIDE: II. THE KINETICS OF THE REACTION OF ETHYLENE OXIDE WITH AMINES IN AQUEOUS SOLUTION

1951 ◽  
Vol 29 (7) ◽  
pp. 575-584 ◽  
Author(s):  
A. M. Eastham ◽  
B. deB. Darwent ◽  
P. E. Beaubien
Keyword(s):  
Aqueous Solution ◽  
Ethylene Oxide ◽  
Order Equation ◽  
Basic Catalysis ◽  
Ion Concentrations ◽  
Hydroxyl Ion ◽  
Wide Range ◽  
Dilute Aqueous Solution ◽  
Ph Range ◽  
Kinetics Of

The kinetics of the reaction of ethylene oxide in dilute aqueous solution at 25°C. with di- and tri-ethylamines, aniline, and pyridine have been investigated over a wide range of hydrogen and hydroxyl ion concentrations. The rates for all four amines were found to be very similar and were accurately expressed by the simple second order equation −d oxide/dl = k(oxide)(amine). The results indicate that basic catalysis does not occur and that catalysis by hydrogen or ammonium-type ions, if it occurs at all, is of no significance in the pH range 4–14.

scholarly journals Kinetics and Mechanism of Oxidation of Isoleucine byN-Bromophthalimide in Aqueous Perchloric Acid Medium

2011 ◽  
Vol 8 (4) ◽  
pp. 1728-1733 ◽  
Author(s):  
N. M. I. Alhaji ◽  
S. Sofiya Lawrence Mary
Keyword(s):  
Acid Medium ◽  
Perchloric Acid ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Halide Ions ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Hypobromous Acid ◽  
Different Temperatures ◽  
Kinetics Of

The kinetics of oxidation of isoleucine withN-bromophthalimide has been studied in perchloric acid medium potentiometrically. The reaction is of first order each in [NBP] and [amino acid] and negative fractional order in [H+]. The rate is decreased by the addition of phthalimide. A decrease in the dielectric constant of the medium increases the rate. Addition of halide ions or acrylonitrile has no effect on the kinetics. Similarly, variation of ionic strength of the medium does not affect the reaction rate. The reaction rate has been determined at different temperatures and activation parameters have been calculated. A suitable mechanism involving hypobromous acid as reactive species has been proposed.

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