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

Octahedral cobalt(III) complexes of the chloropentanimine type. XXX. The thallium(III)-induced aquation of some cis-Halogeno(amine)bis(ethylenediamine)cobalt(III) cations in aqueous solution

1973 ◽  
Vol 26 (6) ◽  
pp. 1235 ◽  
Author(s):  
SC Chan ◽  
SF Chan
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Activation Parameters ◽  
Second Order ◽  
Alternative Possibility ◽  
Order Rate ◽  
Leaving Group ◽  
Activated Complex

The second-order rate constants for the thallium(III)-induced aquation of cis-[Co(en)2(RNH2)Cl]2+ cations, where R is H, Me, Et, Prn, and Pri, have been measured in aqueous solution over a range of temperatures, and the activation parameters calculated. The kinetic results are discussed in terms of a rapid pre-equilibrium formation of an activated complex Co-Cl-Tl, followed by a simple rate-determining aquation in which TlCl2+ acts as the leaving group, although the alternative possibility of a rate-determining attack by Tl3+ cannot be excluded. In the case of R = H, the investigations have been extended to the corresponding bromo cation which reacts some 50 times faster than its chloro analogue.

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.

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 Removal of Cr(VI) from Aqueous Solution Using Modified Pomegranate Peel : Equilibrium and Kinetic Studies

2009 ◽  
Vol 6 (s1) ◽  
pp. S129-S142 ◽  
Author(s):  
Tariq S. Najim ◽  
Suhad A. Yassin
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Kinetic Studies ◽  
Intraparticle Diffusion ◽  
Second Order ◽  
Diffusion Kinetic ◽  
Adsorbent Dosage ◽  
Pseudo Second Order ◽  
Time Required ◽  
System Variables

The present investigation deals with the utilization of modified pomegrenate peel (MPGP) and formaldehyde modified pomegrenate peel (FMPGP) as adsorbents for the removal of chromium Cr(VI) from aqueous solution. A series of experiments were conducted in a batch system to evaluate the effect of system variables. The effect of pH, initial Cr(VI) concentration, contact time, adsorbent dosage and temperature were considered. The optimal pH values of Cr(VI) removal by MPGP and FMPGP were 2.0 and 3.0 respectively. The time required for equilibrium was found to be about 100 minutes. The initial Cr(VI) concentration and adsorbent dosage was found to have large effect on the adsorption of Cr(VI). The maximum uptake capacities were 13.01 and 22.28 mg of Cr(VI) per gram of MPGP and FMPGP respectively. Adsorption kinetic data were tested using pseudo-first order, pseudo-second order, Elovich and intra-particle diffusion models. Kinetic studies showed that the adsorption followed a pseudo second order reaction due to the high correlation coefficient and the agreement between the experimental and calculated values of qe.The adsorption may follow intraparticle diffusion as well, due to the highest values of rate constants for the surface adsorption and intraparticle diffusion kinetic models, the higher values of rate constants are related to an improved bonding between Cr(VI) ions and adsorbent particle.The Dubinin-radushkevich, Freundlich and Tempkin models were the closest fit for the equilibrium data of MPGP and FMPGP.

Free radical mechanisms for the oxidation of 2,3-dihydroxy-2-propenal (triose reductone) by hexacyanoferrate(III)

1985 ◽  
Vol 63 (5) ◽  
pp. 1005-1008 ◽  
Author(s):  
Yasuo Abe ◽  
Takaaki Dohmaru ◽  
Hideo Horii ◽  
Setsuo Taniguchi
Keyword(s):  
Free Radical ◽  
Ionic Strength ◽  
Rate Constants ◽  
Sodium Perchlorate ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Second Order ◽  
Probable Mechanism ◽  
Acidic Media ◽  
The Media

Kinetic studies of the oxidation of 2,3-dihydroxy-2-propenal (triose reductone, RH2) by hexacyanoferrate(III), [Fe(CN)6]3−, were carried out in acidic media ([H+] = 0.02–0.1 M (1 M = 1 mol dm−3)) at various temperatures (10–30° C). The ionic strength of the media (I = 0.04–0.4 M) was adjusted using sodium perchlorate. The second-order rate constants in M−1 s−1 are (0.86 ± 0.06) – (2.83 ± 0.14) for the reactions of hexacyanoferrate(III) with RH2, and [(4.16 ± 0.03) − (12.4 ± 0.2)] × 103 for those with RH− ion. Activation parameters for the oxidation have been reported and compared with those of the oxidation of triose reductone with peroxodisulfate ion. A probable mechanism is proposed for the reaction.

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