Kinetics of aquation of the fluoropentaamminecobalt(III) ion

1970 ◽  
Vol 48 (7) ◽  
pp. 1054-1058 ◽  
Author(s):  
T. W. Swaddle ◽  
W. E. Jones
Keyword(s):  
Ionic Strength ◽  
Rate Coefficient ◽  
Hydrogen Ion ◽  
Fluoride Ion ◽  
Kcal Mole ◽  
First Order ◽  
Order Rate ◽  
Relationship Of ◽  
The Relationship ◽  
Kinetics Of

The kinetics of the hydrogen-ion-independent pathway for the replacement of fluoride in aqueous (NH3)5CoF2+ by H2O have been reinvestigated using a specific fluoride-ion electrode, with due regard for the concomitant autocatalytic loss of the ammine ligands. In perchlorate media of ionic strength 0.1 M, the first-order rate coefficient is 1.22 × 10−6 s−1 at 45°, and the kinetics are represented by ΔH* = 24.4 kcal mole−1 and ΔS* = −9 cal deg−1 mole−1 over the range 35–75° at least. The relationship of these data to those for the aquation of other species of the type ML5Xn+ is discussed.

THE KINETICS OF THE FORMATION OF THE MONOSULPHATO COMPLEX OF IRON (III) IN AQUEOUS SOLUTION

1962 ◽  
Vol 40 (9) ◽  
pp. 1836-1845 ◽  
Author(s):  
G. G. Davis ◽  
W. MacF. Smith
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Ionic Strength ◽  
Continuous Flow ◽  
Hydrogen Ions ◽  
Kcal Mole ◽  
Forward Reaction ◽  
First Order ◽  
Kinetics Of Formation ◽  
Kinetics Of

The kinetics of formation of the monosulphato complex of iron (III) has been examined spectrophotometrically using a continuous-flow technique over the range of temperatures 15.6 to 34.5 °C in an aqueous medium of ionic strength 0.5 and a range of concentrations of hydrogen ions 0.05 to 0.30 M. The experimental data may be interpreted on the assumption that the significant reactions are a bimolecular association opposed by a first-order dissociation [Formula: see text] For the forward reaction ΔH≠ is 18.0 kcal mole−1 and ΔS≠ is 19.4 cal mole−1 deg−1.

THE KINETICS OF THE CHELATION OF NICKEL (II) AND 1,10-PHENANTHROLINE

1964 ◽  
Vol 42 (4) ◽  
pp. 934-940 ◽  
Author(s):  
P. F. Barrett ◽  
W. MacF. Smith
Keyword(s):  
Ionic Strength ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Second Order ◽  
Hydrogen Ion ◽  
Kinetic Behavior ◽  
Ion Concentrations ◽  
Order Rate ◽  
Kinetics Of ◽  
Limiting Values

The kinetics of the formation of the bidentate monocomplex of 1,10-phenanthroline and nickel (II) have been examined spectrophotometrically at ionic strength 0.5 over the range of temperatures 8 to 37 °C and over the range of hydrogen ion concentrations 0.01 to 0.30 molar. The kinetic behavior over the range of conditions is consistent with that found at 25 °C by Margerum, Bystroff, and Banks. The limiting values for the second-order rate constant for the reaction at high acidities have been assessed and imply associated values of ΔH≠and ΔS≠ of 9.5 kcal mol−1 and −5.3 e.u. respectively.

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.

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.

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

scholarly journals Compounds of 6, 13-Diamino-6, 13-Dimethyl-1, 4, 8, 11 - Tetraazacyclotetradecane

2021 ◽  
Author(s):  
◽  
Asokamali Siriwardena
Keyword(s):  
Rate Constants ◽  
Magnetic Measurements ◽  
Order Rate Constant ◽  
Acidic Solutions ◽  
First Order ◽  
Order Rate ◽  
Pendant Arm ◽  
Nickel Copper ◽  
13C Nuclear Magnetic Resonance ◽  
Kinetics Of

<p>The reaction of bis-(diaminoethane)nickel(II) chloride, ([Ni(en)2]Cl2 in methanol with formaldehyde and nitroethane in the presence of triethylamine proceeds readily to produce (6, 13-dimethyl-6, 13-dinitro-1, 4, 8, 11-tetraazacyclotetradecane)nickel(II) chloride, [Ni(dini)] - Cl2. Reduction of the nitro groups of this compound by catalytic hydrogenation yields three isomers of the pendant arm macrocyclic complex (6, 13-diamino-6, 13-dimethyl-1, 4, 8, 11-tetraazachyclotetradecane)nickel(II) chloride, designated a-, b- and c-[Ni(diam)]Cl2. These were separated by fractional crystallization. The aisomer was observed to isomerizes slowly in solution to the b- form. A parallel dissociation reaction of the a- isomer was also observed. The demetallation of a- and b- isomers of the diam complex of nickel by reaction with cyanide or concentrated acid at 140 degrees C produces the macrocycle meso-(6, 13-diamino-6, 13-dimethyl-1, 4, 8, 11-tetraazacyclotetra-decane), diam. A variety of hexamine, pentamine and tetramine complexes of diam with nickel(II), copper(II), cobalt(II) and (III), chromium(III), palladium(II), rhodium(III), zinc(II) and cadmium(II) were prepared. Hexamine and tetramine forms of labile metal complexes could be rapidly and reversibly interconverted by altering the pH. The hexamine cobalt(III) cation, [Co(diam)]3+ was by far the most inert of the prepared cobalt(III) complexes, remaining unaffected in hot acidic solutions. In contrast, a single pendant arm of the hexamine [Cr(diam)]3+ cation could be dissociated in acid. (Two possibly triamine complexes of lead were also prepared). These compounds were characterized by elemental analysis, magnetic measurements, electronic, infrared, 1H and 13C nuclear magnetic resonance spectra. The pendant arm protonation constants (log K) of diam and selected complexes of nickel, copper and palladium were calculated from potentiometric titration measurements at 25 degrees C. The log K values for diam at 25 degrees C (I = 0.1 M NaclO4) were 11.15, 9.7, 6.2 and 5.3. Kinetics of the parallel isomerization and dissociation of a-[Ni(dimH2)]4+ in HCl/NaCl solutions were monitored spectrophotometrically at 50 degrees C. The rate of reaction in acidic solutions showed a non-linear dependency on acid concentration. The observed first order rate constant (kobs) for disappearance of a-[Ni(diamH2)]4+ (by isomerization and dissociation) in 2.0 M HCl, 0.1 M NaOH and 2.0 M NaCl were 3.05 x 10-4, 2.0(3) x 10-2 and 5.0 x 10-5 s-1 respectively. The rate of the dissociation component of the reaction of a-[Ni(diamH2)]4+ in 2.0 M HCl at 50 degrees C was 1.82 x 10-7 s-1. Acid bydrolysis kinetics of (Cu[diamH2])(ClO4)4 in hydrochloric acid and perchloric acid at 50 and 70 degrees C were studied spectrophotometrically. The reactions were slow and the observed first order rate constants were to a first approximation independent of the particular acid or its concentration. The observed first order rate constants were 1 x 10-9 and 8 x 10-9 s-1 at 50 and 70 degrees C respectively. Questions about the nature of the reaction being followed have been raised.</p>

scholarly journals Reactivity of Phenol and Aniline towards Quinolinium Chloro Chromate: A Comparative Oxidation Kinetic Study

2015 ◽  
Vol 59 ◽  
pp. 81-92
Author(s):  
Seplapatty Kalimuthu Periyasamy ◽  
H. Satham Hussain ◽  
R. Manikandan
Keyword(s):  
Oxidation Kinetic ◽  
Activation Parameters ◽  
Dipole Interaction ◽  
Reaction Rates ◽  
Hydrogen Ion ◽  
Aqueous Acetic Acid ◽  
Acetic Acid Medium ◽  
First Order ◽  
Different Temperatures ◽  
Kinetics Of

The kinetics of Oxidation of Phenol and aniline by quinolinium Chlorochromate (QCC) in aqueous acetic acid medium leads to the formation of quinone and azobenzene respectively. The reactions are first order with respect to both Phenol and aniline. The reaction is first order with respect to quinolinium chlorochromate (QCC) and is catalyzed by hydrogen ion. The hydrogen-ion dependence has the form: kobs = a+b [H+]. The rate of oxidation decreases with increasing dielectric constant of solvent, indicating the presence of an ion-dipole interaction. The reaction does not induced the polymerization of acrylonitrile. The retardation of the rate by the addition of Mn2+ ions confirms that a two electron transfer process is involved in the reaction. The reaction rates have been determined at different temperatures and the activation parameters have been calculated. From the above observations kinetic results a probable mechanism have been proposed.

Application of Galvanic Zinc-Iron Coating in the Repair of Transport and Technological Machines

2021 ◽  
Vol 1022 ◽  
pp. 181-193
Author(s):  
Dmitry M. Rozhkov ◽  
Evgenia V. Eltoshkina ◽  
Petr I. Ilyin ◽  
Olga A. Svirbutovich
Keyword(s):  
Experimental Studies ◽  
Iron Alloy ◽  
Resource Saving ◽  
Experimental Base ◽  
Optimal Resource ◽  
Iron Coating ◽  
Saving Mode ◽  
Relationship Of ◽  
The Relationship ◽  
Kinetics Of

The article presents the results of experimental studies to determine the relationship between the electrolysis modes and the properties of electroplating coatings for mathematical modeling of the dynamics of the electrolytic process (MDEP), described by a system of ordinary differential equations due to the complex relationship of the kinetics of chemical reactions, hydrodynamics and mass transfer in the electrolyte flow, the kinematics of electrode plates, and the influence of the electric field of the "anode-cathode" pair on all these processes. At the same time, the experimental base was a series of full-scale experiments to restore the seats of the root supports of cylinder blocks with electroplated coatings. The final result of the research is the procedure for constructing an optimal resource-saving mode of electroplating, which is a zinc-iron alloy.

Coherence analysis of a family of weighted star-composed networks

2019 ◽  
Vol 33 (23) ◽  
pp. 1950264
Author(s):  
Meifeng Dai ◽  
Tingting Ju ◽  
Yongbo Hou ◽  
Jianwei Chang ◽  
Yu Sun ◽  
...  
Keyword(s):  
Kronecker Product ◽  
Future Research ◽  
Weight Factor ◽  
Node Number ◽  
Laplacian Eigenvalues ◽  
First Order ◽  
Successive Generations ◽  
Network Consistency ◽  
Relationship Of ◽  
The Relationship

Recently, the study of many kinds of weighted networks has received the attention of researchers in the scientific community. In this paper, first, a class of weighted star-composed networks with a weight factor is introduced. We focus on the network consistency in linear dynamical system for a class of weighted star-composed networks. The network consistency can be characterized as network coherence by using the sum of reciprocals of all nonzero Laplacian eigenvalues, which can be obtained by using the relationship of Laplacian eigenvalues at two successive generations. Remarkably, the Laplacian matrix of the class of weighted star-composed networks can be represented by the Kronecker product, then the properties of the Kronecker product can be used to obtain conveniently the corresponding characteristic roots. In the process of finding the sum of reciprocals of all nonzero Laplacian eigenvalues, the key step is to obtain the relationship of Laplacian eigenvalues at two successive generations. Finally, we obtain the main results of the first- and second-order network coherences. The obtained results show that if the weight factor is 1 then the obtained results in this paper coincide with the previous results on binary networks, otherwise the scalings of the first-order network coherence are related to the node number of attaching copy graph, the weight factor and generation number. Surprisingly, the scalings of the first-order network coherence are independent of the node number of initial graph. Consequently, it will open up new perspectives for future research.

THE REDUCTION OF CYTOCHROMEcBY HYDROQUINONE

1963 ◽  
Vol 41 (1) ◽  
pp. 231-237 ◽  
Author(s):  
G. R. Williams
Keyword(s):  
Reaction Mechanism ◽  
Ionic Strength ◽  
Rate Equation ◽  
Second Order ◽  
Order Rate ◽  
Ferricytochrome C ◽  
Kinetics Of ◽  
Kinetics Of Reduction ◽  
Order Rate Equation

The kinetics of reduction of ferricytochrome c by hydroquinone have been studied. The reaction does not conform to a simple second-order rate equation and it is demonstrated that the deviations are brought about by the presence of p-quinone, one of the products of the reaction. The accelerating effect of p-quinone is explained tentatively on the basis of an involvement of the semi-quinone. The effects on the reaction of pH, ionic strength, and temperature are reported and used to suggest features of the reaction mechanism.

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