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 Studies of the Reactions of Cyanide Ion and 1,3,5-Trinitrobenzene in Ethanol, n-Propanol, Isopropanol, and t-Butanol at 25.0 °C

1974 ◽  
Vol 52 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Leong Huat Gan ◽  
Albert Richard Norris
Keyword(s):  
Rate Constants ◽  
Kinetic Studies ◽  
Specific Rate ◽  
Cyanide Ion ◽  
Solvent Parameter ◽  
Kinetics Of

The specific rate constants for the formation of the 1:1 1,3,5-trinitrobenzene – cyanide ion σ-complex in ethanol, n-propanol, isopropanol, and t-butanol are 442 ± 14,932 ± 30, 2.45 ± 0.10 × 103 and 1.06 ± 0.05 × 105 M−1 s−1, respectively. A plot of log kvs. Dimroth's solvent parameter Et is linear with slope −0.25. The kinetics of the reactions of cyanide ion and 1,3,5-trinitrobenzene in ethanol and n-propanol are complicated by alcoholysis of cyanide ion which yields the corresponding alkoxide ion and the 1:1 1,3,5-trinitrobenzene–alkoxide ion σ-complex.

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.

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.

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.

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.

Homogeneous Hydrogenation of Unsaturated Carboxylic Acids Using Chlororhodate(I) Complexes and Rhodium(I) Diethylsulfide Complexes

1975 ◽  
Vol 53 (6) ◽  
pp. 797-804 ◽  
Author(s):  
Brian R. James ◽  
Flora T. T. Ng
Keyword(s):  
Carboxylic Acids ◽  
Rate Constants ◽  
Maleic Acid ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Homogeneous Hydrogenation ◽  
Chloride Solutions ◽  
Rate Determining Step ◽  
Square Planar ◽  
Unsaturated Carboxylic Acids

N,N-Dimethylacetamide solutions of the cyclooctene complex [Rh(C8H14)2Cl]2, in the presence of excess chloride or diethylsulfide, are effective for the homogeneous hydrogénation of unsaturated carboxylic acids at ca. 80 °C and 1 atm H2. Kinetic studies on the hydrogenation of maleic acid are consistent with a rate determining step involving oxidative addition of H2 to square planar rhodium(I) olefin species. Rate constants and activation parameters agree with those determined previously from similar studies using corresponding rhodium(III) complexes and give confirmation that rhodium(I) catalysts are involved in the rhodium(III) systems. Discussion of the systems is limited by the somewhat uncertain nature of the catalysts; however, chlororhodate(I) species are involved in the chloride solutions, and bis(diethylsulfide) complexes appear likely in the sulfide systems.

scholarly journals Kinetic studies on the oxidation of nitrite by horseradish peroxidase and lactoperoxidase.

1999 ◽  
Vol 46 (4) ◽  
pp. 919-927 ◽  
Author(s):  
L Gebicka
Keyword(s):  
Horseradish Peroxidase ◽  
Nitrogen Dioxide ◽  
Rate Constants ◽  
Kinetic Studies ◽  
The Other ◽  
Stopped Flow ◽  
Nitrite Concentration ◽  
Flow Measurements ◽  
Activity Measurements ◽  
Compound Ii

The reaction of nitrite (NO2-) with horseradish peroxidase and lactoperoxidase was studied. Sequential mixing stopped-flow measurements gave the following values for the rate constants of the reaction of nitrite with compounds II (oxoferryl heme intermediates) of horseradish peroxidase and lactoperoxidase at pH 7.0, 13.3 +/- 0.07 mol(-1) dm3 s(-1) and 3.5 +/- 0.05 x 10(4) mol(-1) dm3 s(-1), respectively. Nitrite, at neutral pH, influenced measurements of activity of lactoperoxidase with typical substrates like 2,2'-azino-bis[ethyl-benzothiazoline-(6)-sulphonic acid] (ABTS), guaiacol or thiocyanate (SCN-). The rate of ABTS and guaiacol oxidation increased linearly with nitrite concentration up to 2.5-5 mmol dm(-3). On the other hand, two-electron SCN- oxidation was inhibited in the presence of nitrite. Thus, nitrite competed with the investigated substrates of lactoperoxidase. The intermediate, most probably nitrogen dioxide (*NO2), reacted more rapidly with ABTS or guaiacol than did lactoperoxidase compound II. It did not, however, effectively oxidize SCN- to OSCN-. NO2- did not influence the activity measurements of horseradish peroxidase by ABTS or guaiacol method.

Kinetic studies of ring closures in platinum(II) chelates. Rate constants and activation parameters for chelation of platinum(II) by bis(2-aminoethyl) sulfide in aqueous solution

1979 ◽  
Vol 18 (6) ◽  
pp. 1451-1454 ◽  
Author(s):  
G. Albertin ◽  
E. Bordignon ◽  
A. A. Orio ◽  
B. Pavoni ◽  
Harry B. Gray
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Activation Parameters ◽  
Kinetic Studies
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