Kinetic study of formation of nickel (II)-isoquinoline complex in water and nonaqueous solvents

1976 ◽  
Vol 54 (16) ◽  
pp. 2540-2547 ◽  
Author(s):  
Praphulla Kumar Chattopadhyay ◽  
Byron Kratochvil
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Activation Parameters ◽  
Nonaqueous Solvents ◽  
Stopped Flow ◽  
Multidentate Ligands ◽  
Monodentate Ligands

Rate constants and activation parameters for the formation of the monocomplex of nickel(II) with isoquinoline in water, methanol, dimethylsulfoxide, and N,N-dimethylformamide were obtained from measurements by stopped-flow spectrophotometry. The data are compared with previously reported work by other authors for substitution at nickel(II) with related monodentate and multidentate ligands. The results in all solvents except dimethylsulfoxide are consistent with an Id mechanism. In dimethylsulfoxide substitution at nickel(II) proceeds in a similar way for all monodentate ligands but whether the mechanism is Id or D cannot be ascertained.

Kinetic Study of the Oxidation of Alcohols with Quaternary Ammonium Permanganates

1993 ◽  
Vol 58 (8) ◽  
pp. 1777-1781 ◽  
Author(s):  
Robert Šumichrast ◽  
Vladislav Holba
Keyword(s):  
Kinetic Study ◽  
Catalytic Reaction ◽  
Rate Constants ◽  
Quaternary Ammonium ◽  
Iterative Procedure ◽  
Activation Parameters ◽  
Reaction Products ◽  
Thermodynamic Activation Parameters ◽  
Oxidation Of Alcohols ◽  
Kinetics Of

Kinetics of the oxidation of 2-propanol, 1-butanol, and 1-pentanol with tetraalkylammonium permanganates have been investigated as function of temperature. The studied reactions are partly autocatalytic, colloidal manganese dioxide as one of the reaction products has been identified as the autocatalyst.A computerized iterative procedure has been used in order to obtained the rate constants of both non-catalytic and catalytic reaction steps together with the thermodynamic activation parameters.

Mechanism of bromination of a quaternary pyrimidinium cation. Change of rate determining step with acidity

1978 ◽  
Vol 56 (23) ◽  
pp. 2970-2976 ◽  
Author(s):  
Oswald S. Tee ◽  
David C. Thackray ◽  
Charles G. Berks
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Aqueous Media ◽  
Stopped Flow ◽  
Flow Method ◽  
High Acidity ◽  
Rate Determining Step ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of bromination of the 1,2-dihydro-1,3-dimethyl-2-oxopyrimidinium cation (Q+) in aqueous media (pH 0–5) have been studied using the stopped-flow method. At the higher acidities (pH < 2) the results are consistent with rate determining attack by bromine upon the pseudobase (QOH), whereas at low acidities (pH > 4) it appears that pseudobase formation is rate determining. The change occurs because at high acidity the reversal of the pseudobase QOH to the cation is fast relative to bromine attack, whereas at low acidity the converse is true. Results obtained at intermediate acidities (pH 2–4) are consistent with this interpretation.A separate kinetic study of pseudobase formation (and decomposition) yielded rate constants in good agreement with those derived from the bromination study.

scholarly journals Kinetic and High-Pressure Mechanistic Investigation of the Aqua Substitution in the Trans-Aquaoxotetracyano Complexes of Re(V) and Tc(V): Some Implications for Nuclear Medicine

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
J. Mattheus Botha ◽  
Andreas Roodt
Keyword(s):  
High Pressure ◽  
Nuclear Medicine ◽  
Kinetic Study ◽  
Rate Constants ◽  
Formation Rate ◽  
Activation Parameters ◽  
Second Order ◽  
Associative Mechanism ◽  
Mechanistic Investigation

A kinetic study of the aqua substitution in the [TcO(OH2)(CN)4]− complex by different thiourea ligands (TU = thiourea, NMTU = N-methyl thiourea, NNDMTU = N, N′-dimethylthiourea) yielded second-order formation rate constants (25∘C) as follows [NNDMTU, NMTU, TU, respectively]: kf = 11.5 ± 0.1, 11.38 ± 0.04, and 7.4 ± 0.1 M−1s−1, with activation parameters: ΔHkf#:55±2, 42±3, 35±5 kJ mol−1; ΔSkf#:−40±8, −84±11, −110±17 J K−1mol−1. A subsequent high-pressure investigation of the aqua substitution in the [ReO(OH2)(CN)4]− and [TcO(OH2)(CN4)]− complexes by selected entering ligands yielded ΔVkf# values as follows: Re(V): −1.7±0.3(NCS−), −22.1±0.9 (TU) and for Tc(V): −3.5±0.3(NCS−), −14±1 (NNDMTU), and−6.0±0.5 (TU) cm3mol−1, respectively. These results point to an interchange associative mechanism for the negative NCS− as entering group but even a pure associative mechanism for the neutral thiourea ligands.

Kinetic studies of the reactions of 4-nitrobenzofuroxan with cyanide ion and isopropoxide ion in isopropanol

1980 ◽  
Vol 58 (16) ◽  
pp. 1691-1696 ◽  
Author(s):  
Michael E. Moir ◽  
Albert R. Norris
Keyword(s):  
Rate Constants ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Specific Rate ◽  
Stopped Flow ◽  
Cyanide Ion ◽  
Temperature Range ◽  
Flow Reaction

Kinetic studies of the reactions in isopropanol of 4-nitrobenzofuroxan with cyanide ion and isopropoxide ion have been carried out over the temperature range 15.0 to 35.0 °C. For both bases, the first species identifiable using stopped-flow reaction techniques is postulated to be a C-7 σ-complex of 4-nitrobenzofuroxan and base. Specific rate constants and activation parameters for the formation of these σ-complexes are compared to corresponding data relating to the formation of cyanide ion and isopropoxide ion—σ-complexes of 1,3,5-trinitrobenzene in isopropanol.

Kinetic and Mechanistic Study on the Reactions of [Pd(dien)H2O]2+ and [Pt(dien)H2O]2+ with L-Cysteine and S-Methyl-L-cysteine

2005 ◽  
Vol 58 (7) ◽  
pp. 544 ◽  
Author(s):  
Biljana V. Petrović ◽  
Živadin D. Bugarčić
Keyword(s):  
Rate Constants ◽  
Activation Parameters ◽  
Second Order ◽  
Mechanistic Study ◽  
Stopped Flow ◽  
Substitution Reactions ◽  
Order Rate ◽  
Increase With Increase ◽  
Naclo4 Solution ◽  
Entropy Of Activation

The reactions of [Pd(dien)H2O]2+ and [Pt(dien)H2O]2+ (dien = diethylenetriamine or 1,5-diamino-3-azapentane) with l-cysteine and S-methyl-l-cysteine were studied in an aqueous 0.10 M NaClO4 solution using stopped-flow and conventional UV-vis spectrophotometry. The second-order rate constants for the reactions of [Pd(dien)H2O]2+ at pH 1.0 are k1298 = (9.11 ± 0.11) × 102 M−1 s−1 for l-cysteine, and k1298 = (33.79 ± 0.63) × 102 M−1 s−1 for S-methyl-l-cysteine. The second-order rate constants for the reactions of [Pt(dien)H2O]2+ at pH 1.0 with l-cysteine is k1298 = (1.28 ± 0.08) × 10−2 M−1 s−1 and for S-methyl-l-cysteine is k1298 = (3.87 ± 0.02) × 10−2 M−1 s−1. Activation parameters were determined for all reactions, and the negative values of entropy of activation support an associative complex formation mechanism. Substitution reactions were also studied at pH 0.5, 1.0, and 1.5. The rate constants increase with increase in pH. These results are discussed in terms of protolitic equilibrium.

Aromatic substitutions with carbanion nucleophiles. IV. The kinetics and mechanism of the reaction of picryl bromide with diethylmalonate anion

1977 ◽  
Vol 55 (14) ◽  
pp. 2664-2669 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Anna E. Matinopoulos-Scordou
Keyword(s):  
Equilibrium Constant ◽  
Rate Constants ◽  
Activation Parameters ◽  
Solvent System ◽  
Stopped Flow ◽  
Substitution Product ◽  
Picryl Chloride ◽  
Uv Visible ◽  
The Individual ◽  
Mechanism Of The Reaction

The reaction of picryl bromide with sodium diethylmalonate has been studied in benzene–DMSO 7:1 v/v by means of stopped-flow and uv–visible spectrophotometers. A Meisenheimer-like intermediate was detected, decomposing to yield the stable violet anion of the substitution product. The rate constants of the individual steps have been measured and the activation parameters calculated. Comparison with those obtained for picryl chloride support a bimolecular substitution via the 1,1-complex. The reaction with 1,3,5-trinitrobenzene is too fast to be measured in the same solvent system. The equilibrium constant is estimated to be of the order of 104–105.

scholarly journals Kinetics of the Reversible Transformation of 2,3-Dioxogulonic Acid into its Enol as a Function of the pH of the Medium

1978 ◽  
Vol 33 (10) ◽  
pp. 1184-1189
Author(s):  
J. Zuluaga ◽  
P. Martínez
Keyword(s):  
Kinetic Study ◽  
Equilibrium Constant ◽  
Rate Constants ◽  
Disodium Salt ◽  
Stopped Flow ◽  
Free Energies ◽  
Reversible Transformation ◽  
Flow Method ◽  
Kinetic Coefficients ◽  
Kinetics Of

Abstract 2,3-dioxogulonic acid and the disodium salt of its enol were synthesised, isolated and identified both chemically and spectroscopically. A kinetic study was carried out on its equilibrium by means of the “stopped flow” method for rapid processes, and the rate constants for the forward and backward reaction were determined as a function of the pH of the medium. The kinetic coefficients involved, equilibrium constant and Gibbs free energies were also determined.

The Lewis-acidity of square-planar nickel(II) complexes. III. A kinetic study of the effects of substituents on the addition of 1,10-Phenanthroline to Bis(monothioacetylacetonato)nickel(II) and Bis(dithiophosphato)nickel(II) complexes in toluene

1978 ◽  
Vol 31 (7) ◽  
pp. 1439 ◽  
Author(s):  
MU Fayyaz ◽  
MW Grant
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Activation Parameters ◽  
Adduct Formation ◽  
Second Order ◽  
Lewis Acidity ◽  
Order Rate ◽  
Measured Rate ◽  
Square Planar ◽  
Inductive Effects

The second-order rate constants and activation parameters for the addition of 1,10-phenanthroline to bis(dialkyldithiophosphato)nickel(II) complexes and substituted bis(monothioacetylacetonato)-nickel(II) complexes in toluene have been measured. Rate constants are in the range 102-108 1. mol-1 s-1 at 25°C, while ΔH‡ is in the range 10-50 kJ mol-1 and ΔS‡ is in the range from -30 to -110 J mol-1 K-1. The higher rate constants, smaller ΔH‡ and more negative ΔS‡ values are associated with complexes with electron- withdrawing substituents. The results are related to the thermo- dynamics of adduct formation, the inductive effects of the substituents and the pKa of the ligands.

Kinetics and mechanism of oxidation of hydroxylamine by hexachloroiridate(IV) ion in buffer solutions

1993 ◽  
Vol 71 (12) ◽  
pp. 2164-2170 ◽  
Author(s):  
Ms. Rekha ◽  
Aditya Prakash ◽  
Raj N. Mehrotra
Keyword(s):  
Acetic Acid ◽  
Spectral Analysis ◽  
Rate Constants ◽  
Main Product ◽  
Activation Parameters ◽  
Acetate Buffer ◽  
Stopped Flow ◽  
Stoichiometric Ratio ◽  
Buffer Solutions ◽  
Mechanism Of Oxidation

The oxidation of hydroxylammonium ion by [IrCl6]2− ion in acetic acid – acetate buffer solutions, studied by stopped flow, has the stoichiometric ratio Δ[IrCl6]2−/Δ[NH2OH] = 1. The oxidation involves the species [IrCl6]2− and NH3OH+ although spectral analysis of the spent reaction mixture indicates [IrCl5(OH2)]2− to be the main product (almost to the extent of 80%). This anomaly arises because of the aquation of the reduced product [IrCl6]3−. The rate is retarded both by H+ and Cl− ions and the plots of [Formula: see text] against respective concentrations are linear. The proposed mechanism is given by reactions [i]–[v].[Formula: see text]The values of the rate constants at 25 °C are as follows: k1 = 147 dm3 mol−1 s−1 and 102ketKia = 2.8 s−1. The related activation parameters are [Formula: see text], and,[Formula: see text], and [Formula: see text] and [Formula: see text], respectively. The value of Kipd is 2.91 ± 0.03 mol dm−3 and that of Kipa (= 1/Kipd) is 0.344 ± 0.004 dm3 mol−1; both values are almost independent of temperature.

Kinetic Study of the Reaction between Substituted Triphenylmethyl Perchlorates with Pyridines in Nitromethane and 1,2-Dichloroethane Solvents

1975 ◽  
Vol 53 (22) ◽  
pp. 3408-3413 ◽  
Author(s):  
Chang B. Kim ◽  
Kenneth T. Leffek
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Activation Parameters ◽  
Second Order ◽  
Saturation Effect ◽  
Bond Breaking ◽  
Carbonium Ion ◽  
Enthalpy Of Activation ◽  
Substituted Pyridines ◽  
Nitrogen Bond

Second-order rate constants at 25 °C have been measured for the reaction of triphenylmethyl carbonium ion with pyridine and substituted pyridines in nitromethane and 1,2-dichloroethane solvent. The activation parameters are in the range 1 to 3 kcal mol−1 for the enthalpies of activation and −20 to −45 cal mol−1 deg−1 for the entropies of activation. The results are compared to the analogous measurements for Menschutkin reactions and it is concluded that the enthalpy of activation of a Menschutkin reaction results mainly from the bond breaking process and solvation changes associated with it, since the carbon-nitrogen bond making process seems to be entropy controlled.Rate measurements have also been made for 2-methylpyridine reacting with a series of para-substituted triphenylmethyl carbonium ion substrates in 1,2-dichloroethane solvent. A plot of log k2vs ∑σ+ is non-linear and the curvature is interpreted as a saturation effect.

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