Etude cinétique du système Cu(II)–adénine

1973 ◽  
Vol 51 (20) ◽  
pp. 3322-3328
Author(s):  
G. Boivin ◽  
M. Zador
Keyword(s):  
Exchange Reaction ◽  
Reaction Rates ◽  
Stopped Flow ◽  
Parallel Reaction ◽  
Kinetics Of Formation ◽  
Protonated Species ◽  
Kinetics Of

The kinetics of formation and dissociation of Cu(II)–adenine complexes have been studied by stopped flow and relaxation methods.Between pH 3.5 and 5 the formation of Cu(II)•aH is too fast to be measured; formation of Cu(II)•(aH)2 has been studied and rate parameters have been determined. At pH < 3 protonated species make an important contribution to measured reaction rates. In basic media two different complexes have been investigated. The exchange reaction with EDTA proceeds by two parallel reaction paths.The mechanism of these reactions is discussed and compared with that proposed for the Cu(II)–adenosine system.La cinétique de la formation et de la dissociation de divers complexes Cu(II)–adénine a été étudiée par les méthodes de la relaxation thermique et du "flux stoppé".

Kinetic and Equilibrium Studies of the Reactions of Cyanide Ion with 1,3,5-Trinitrobenzene, 2,4,6-Trinitroanisole, and 2,4,6-Trinitrotoluene in Isopropanol

1974 ◽  
Vol 52 (1) ◽  
pp. 8-17 ◽  
Author(s):  
Leong Huat Gan ◽  
Albert Richard Norris
Keyword(s):  
Standard Enthalpy ◽  
Equilibrium Constants ◽  
Activation Parameters ◽  
Stopped Flow ◽  
Cyanide Ion ◽  
Equilibrium Studies ◽  
Kinetics Of Formation ◽  
Kinetics Of

Equilibrium constants for the formation of 1:1 cyanide ion σ-complexes with 1,3,5-trinitrobenzene, 2,4,6-trinitroanisole, and 2,4,6-trinitrotoluene have been determined spectrophotometrically over a range of temperatures. Standard enthalpy (ΔH0) and entropy (ΔS0) changes associated with each reaction have been evaluated. The kinetics of formation of the σ-complexes have been investigated by means of a stopped-flow technique and the activation parameters characterizing the formation of each complex have been determined. Evidence is presented which indicates the cyanide ion – 2,4,6-trinitroanisole σ-complex formed in isopropanol contains the cyanide ion bonded exclusively at the C-3 position.

Absolute Light Scattering Calibration of the Stopped-Flow Spectrophotometer with Application to the Kinetics of Formation of Monodispersed Colloidal Hematite

1987 ◽  
Vol 41 (3) ◽  
pp. 402-407 ◽  
Author(s):  
Wan Peter Hsu ◽  
Ramesh C. Patel ◽  
Egon Matijevic
Keyword(s):  
Colloidal Silica ◽  
Temperature Jump ◽  
Scattered Light ◽  
Calibration Method ◽  
Stopped Flow ◽  
Flow Temperature ◽  
Hydrous Oxides ◽  
Solid Iron ◽  
Kinetics Of Formation ◽  
Kinetics Of

A calibration method based on absolute intensities of scattered light from colloidal silica was developed to standardize the stopped-flow temperature jump spectrophotometer (SFTJ). The need for such calibration was exemplified by the study of the temperature effect on the Rayleigh ratio changes during the formation of solid iron (hydrous) oxides.

Kinetics of the Anation Reaction of Nickel(II) and 1,10-Phenanthroline in Ethanol

1972 ◽  
Vol 50 (23) ◽  
pp. 3861-3865 ◽  
Author(s):  
M. L. Sanduja ◽  
W. MacF. Smith
Keyword(s):  
Rate Constant ◽  
Sodium Perchlorate ◽  
Order Rate Constant ◽  
Stopped Flow ◽  
Tetrabutyl Ammonium ◽  
Kinetics Of Formation ◽  
Kinetics Of ◽  
Nickel Perchlorate ◽  
Anation Reaction ◽  
Made In

The kinetics of formation of the monophenanthroline complex of nickel(II) in ethanol has been studied using stopped-flow methods over the temperature range 7 to 35 °C. Tetrabutyl ammonium perchlorale in concentration 0.044 M does not affect the rate appreciably, sodium perchlorate at the same concentration depresses the rate significantly. Most measurements were made in the absence of electrolytes other than nickel perchlorate and a trace of perchloric acid. The second order rate constant is not significantly dependent on the nickel(II) concentration over a four-fold change in value indicating that the concentration of encounter pairs is small relative to the concentration of the free reactants. The rate constant at 25 °C (31 × 103 M−1 s−1)is consistent with a dissociative interchange mechanism and the rate constant for ethanol exchange on nickel. However, the value of ΔH≠ for the overall reaction (15.9 ± 1.0 kcal mol−1) is about 5 kcal mol−1 higher than that reported for ethanol exchange.

Effect of short-chained sodium alkylsulfate micelles on the kinetics of metal complex formation

1981 ◽  
Vol 59 (9) ◽  
pp. 1361-1367 ◽  
Author(s):  
Paul D. I. Fletcher ◽  
Vincent C. Reinsborough
Keyword(s):  
Alkyl Chain ◽  
Binding Constants ◽  
Micelle Formation ◽  
Reaction Rates ◽  
Bidentate Ligand ◽  
Alkyl Chain Length ◽  
Stopped Flow ◽  
Micellar Solutions ◽  
Kinetics Of ◽  
Micelle Surface

The kinetics of the reaction between Niaq2+ and the bidentate ligand pyridine-2-azo-p-dimethylaniline (PADA) have been investigated in micellar solutions of sodium decyl-, octyl-, and hexylsulfates using the stopped-flow technique. The rate of enhancement decreased with decreasing alkyl-chain length and from the Berezin or Robinson model could be quantitatively related to the independently measured binding constants of Ni2+ ion and PADA to the micelle surface. The dramatic effect of micelles upon the reaction rates in different directions of the Ni2+/PADA and the Ni2+/murexide reactions served as sensitive indicators of the cmc even at the very limit of micelle formation which relatively concentrated sodium hexylsulfate solutions represent.

Kinetics of Formation of Vesicles from Lecithin/Sodium Xylenesulfonate Micelles from Stopped-Flow Measurements

Langmuir ◽  
1998 ◽  
Vol 14 (3) ◽  
pp. 590-594 ◽  
Author(s):  
Samuel E. Campbell ◽  
Zhiqiang Zhang ◽  
Stig E. Friberg ◽  
Ramesh Patel
Keyword(s):  
Stopped Flow ◽  
Flow Measurements ◽  
Kinetics Of Formation ◽  
Kinetics Of

Kinetics of the Reaction of Nickel(II) and 2,2′-Bipyridine in Ethanol

1973 ◽  
Vol 51 (23) ◽  
pp. 3975-3977 ◽  
Author(s):  
M. L. Sanduja ◽  
W. MacF. Smith
Keyword(s):  
Kinetic Parameters ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Second Order ◽  
Stopped Flow ◽  
Ligand Specificity ◽  
Temperature Range ◽  
Kinetics Of Formation ◽  
The Difference ◽  
Kinetics Of

The kinetics of formation of the monobipyridine complex of nickel(II) in ethanol has been studied with stopped-flow methods over the temperature range 7 to 35 °C. The value of the second order rate constant kf at 25 °C of 6.6 × 10−3M−1 s1 and the values of ΔH≠ (10.1 ± 1.0 kcal mol−1) and of ΔS≠ (−7.3 ± 3.4 cal deg−1 mol−1) are close to the corresponding values for ethanol exchange on nickel(II) and suggest that the mechanism is dissociative interchange. However the difference in the values of the kinetic parameters of this reaction and those previously reported for the reactions involving the chemically similar phenanthroline imply a degree of ligand specificity for the reactions in ethanol which is considerably larger than is the case for reactions in water and methanol and that a common Id mechanism with monodentate formation being rate controlling is not applicable to both reactions.

The Kinetics of Formation Of Nanocrystalline γ-Ni-Fe During Mechano-Chemical Synthesis

1999 ◽  
Vol 577 ◽  
Author(s):  
P. Knorr ◽  
B.S. Kim ◽  
J.S. Lee
Keyword(s):  
Solid Solution ◽  
Experimental Study ◽  
Chemical Synthesis ◽  
Reaction Rates ◽  
Kinetics Of Formation ◽  
Kinetics Of

ABSTRACTAn experimental study of the kinetics of the three partial processes involved in the mechano-chemical synthesis of nanocrystalline (nc) Ni-Fe is presented. These processes are the reduction of nc NiO, the reduction of nc Fe2O3, and the alloying of Ni and Fe to a γ-Ni-Fe solid solution. Fr the reaction rates of the reduction of nc NiO and nc Fe2O3 activation enthalpies of 82 kJ mol−1 and 47 kJ mol− were obtained. The progress of the overall synthesis was found to follow the sequence ‘NiO red. → Fe2O3 red. → γ-Ni-Fe form.’.

Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone

1979 ◽  
Vol 44 (3) ◽  
pp. 912-917 ◽  
Author(s):  
Vladimír Macháček ◽  
Said A. El-bahai ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrochloric Acid ◽  
Dilute Hydrochloric Acid ◽  
Base Catalysis ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Rate Limiting ◽  
Kinetics Of

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.

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