Thermodynamics and kinetic investigation of electron transfer reactions of surfactant cobalt(iii) complexes containing diimine ligands with iron(ii) in the presence of liposome vesicles and amphiphilic salt media

RSC Advances ◽  
2014 ◽  
Vol 4 (99) ◽  
pp. 56068-56073 ◽  
Author(s):  
Karuppiah Nagaraj ◽  
Subramanian Sakthinathan ◽  
Sankaralingam Arunachalam
Keyword(s):  
Electron Transfer ◽  
Absorption Spectroscopy ◽  
Order Conditions ◽  
Transfer Reactions ◽  
Kinetic Investigation ◽  
First Order ◽  
Diimine Ligands ◽  
Different Temperatures ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of reductions of surfactant cobalt(iii) complexes by iron(ii) in liposome vesicles (DPPC) and amphiphilic salt ((BMIM)Br) were studied at different temperatures by UV-Vis absorption spectroscopy method under pseudo first order conditions using an excess of the reductant.

Kinetics and mechanism of aminolysis of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones

1992 ◽  
Vol 70 (10) ◽  
pp. 2515-2519 ◽  
Author(s):  
Sharifa S. Alkaabi ◽  
Ahmad S. Shawali
Keyword(s):  
Rate Constants ◽  
Activation Parameters ◽  
Order Conditions ◽  
Kinetics And Mechanism ◽  
Hammett Equation ◽  
Third Order ◽  
First Order ◽  
Different Temperatures ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of the reactions of a series of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones 1 with n-butylamine and piperidine were studied spectrophotometrically in dioxane, ethanol, and cyclohexane under pseudo-first-order conditions and at different temperatures. The relation k1(obs) = k2[amine] + k3[amine]2 was found applicable for all reactions studied in either dioxane or ethanol. However, in cyclohexane the n-butylaminolysis of 1 followed only third-order kinetics k1(obs) = k3[n-BuNH2]2. The kinetics of the reaction of 1 with n-butylamine in the presence of catalytic amounts of triethylamine in dioxane followed the equation: k1(obs)k2 = [n-BuNH2] + k3[n-BuNH2]2[Formula: see text] [Et3N]. The rate constants k2 and k3 correlated well with the Hammett equation and the corresponding activation parameters were determined. The results were interpreted in terms of a mechanism involving solvent- and amine-catalyzed processes.

Electron-Transfer Reactions in Non-Aqueous Media. VI. A Temperature-Dependence Study of the Reduction of cis-[CoCl2(en)2]+ by Iron(II) in Me2SO

1979 ◽  
Vol 32 (10) ◽  
pp. 2275 ◽  
Author(s):  
L Spiccia ◽  
DW Watts
Keyword(s):  
Electron Transfer ◽  
Temperature Dependence ◽  
Transfer Process ◽  
Iron Atom ◽  
Aqueous Media ◽  
Transfer Reactions ◽  
Electron Transfer Process ◽  
First Order ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of the reduction of cis-[CoCl2(en)2] � (en = ethylenediamine) by iron(II) in Me2SO have been studied at four temperatures. The rate law has the form d[CoIII]/dt = kK [COIII][FeII]/(1+K[FII]) The pseudo-first-order rate constants determined at high [Fell] have been resolved into k and K, and their independent temperature dependence has been studied. The results are totally consistent with an inner-sphere electron-transfer process in which the precursor complex contains a double bridge using both the cis-chloro ligands and in which the iron atom is octahedrally coordinated.

Electron-Transfer Reactions in Non-Aqueous Media. V. Solvent Effects in the Reduction of CoN3(NH3)52+ by Iron(II)

1979 ◽  
Vol 32 (10) ◽  
pp. 2139 ◽  
Author(s):  
TJ Westcott ◽  
DW Watts
Keyword(s):  
Electron Transfer ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Transfer Reactions ◽  
Tetrahedral Coordination ◽  
First Order ◽  
Precursor Complex ◽  
Stage Process ◽  
Pseudo First Order ◽  
Reversible Formation

The reduction of CoN3(NH3)52+ by iron(II) is rate-determined by a two-stage process involving the reversible formation of an azide-bridged precursor complex prior to electron transfer in each of the solvents water, Me2SO, aqueous Me2SO and HCONMe2. The activation parameters in H2O and Me2SO, and the trends shown with increasing Me2SO concentrations in aqueous Me2SO, are similar to the properties of the previously studied CoCl(NH3)52+ and CoBr(NH3)52+ systems and contrast with the reduction of COF(NH3)52+. The results are consistent with a bridged precursor complex octahedral at both the iron and cobalt atoms in water but with tetrahedral coordination about the iron in Me2SO. In HCONMe2, as in the reduction of COF(NH3)52+, COCl(NH3)52+ and COBr(NH3)52+, the precursor complex is a significant part of the reacting solutions, and as a result the experimental pseudo-first-order rate constants for the loss of CoIII are not linearly dependent on the concentration of FeII. The initial spectra of the reacting solutions in this system also indicate significant concentrations of the precursor complex.

Kinetische Untersuchung der Chemilumineszenz von 7-Dimethyl-amino-naphthalin-1.2-dicarbonsäurehydrazid in wäßrig alkalischem Wasserstoffperoxid in Gegenwart von Hämin / Kinetic Investigation of the Chemoluminescence of 7-Dimethyl-amino-naphthalin-1,2-dicarbonic-acid-hydrazid in aqueous alcaline H2O2 in Presence of Hemin

1970 ◽  
Vol 25 (5) ◽  
pp. 484-491 ◽  
Author(s):  
Hans-Friedrich Eicke ◽  
Helmut Fiege ◽  
Karl-Dietrich Gundermann
Keyword(s):  
Temporal Change ◽  
Order Conditions ◽  
Stopped Flow ◽  
Kinetic Investigation ◽  
Reaction Step ◽  
Absorption Change ◽  
First Order ◽  
Light Production ◽  
Pseudo First Order ◽  
Primary Oxidation

The chemoluminescence-system: DNH/NaOHaq/H2O2/hemin was investigated with the help of a “stopped-flow-technique”. By use of an optical cut-off-filter the chemoluminescence- (514 nm), and the absorptionband (325 nm) resp. could be separated which proved impossible with luminol. In this way we could follow the temporal change of chemoluminescence and of absorption of DNH: the latter dropped coutinually with progress of the reaction while the chemoluminescence-intensity passed through a maximum before it decreased according to the same rate law (pseudo first order conditions as for DNH) which governs the absorption change of DNH. The oxidation of DNH is rate-determining and of first order as to DNH, H2O2 and (possibly) NaOH (k1 = 1,5·10-3 s-1-1 M-2). The kinetic interpretation of the chemoluminescence-maxima confirmed this result. The light production occurred in a very fast secondary reaction step (k2 ≫ k1) following the oxidation of the hydrazid and with H2O2 participating. Diazochinone is assumed to be a primary oxidation product.

scholarly journals Kinetics of Oxidation of Tryptophan by Sodium Hypochlorite

1981 ◽  
Vol 36 (3) ◽  
pp. 359-361 ◽  
Author(s):  
Thomas Rausch ◽  
Frieder Hofmann ◽  
Willy Hilgenberg
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Sodium Hypochlorite ◽  
Arrhenius Plot ◽  
Ph Dependence ◽  
Order Conditions ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Pseudo First Order ◽  
Kinetics Of

AbstractThe oxidation of tryptophan to 3-indoleacetaldehyde with sodium hypochlorite was investigated with 14C labelled DL-tryptophan. The reaction was performed under pseudo first order conditions. From the pH dependence of the reaction it was concluded that only the unprotonated tryptophan is converted to the aldehyde. The activation energy is 35 ± 2.2 (SE) kJ x mol-1 as derived from the Arrhenius plot. Variing the pH between 8.5 and 11.0 and the temperature in the range from 298 K to 318 K did not alter the selectivity of the reaction as confirmed by TLC of the product (purity ≧ 90%). A possible reaction mechanism is proposed.

scholarly journals Nonenzymatic NADH-Dependent Reduction of Keggin-Type 12-Tungstocobaltate(III) in Aqueous Medium

2011 ◽  
Vol 8 (3) ◽  
pp. 1152-1157
Author(s):  
Prabla Kumari ◽  
Alaka Das ◽  
Dillip Kumar Baral ◽  
A. K. Pattanaik ◽  
P. Mohanty
Keyword(s):  
Electron Transfer ◽  
Transition State ◽  
Aqueous Medium ◽  
Transfer Reaction ◽  
Activation Parameters ◽  
Electron Transfer Reaction ◽  
Transfer Reactions ◽  
Electron Transfer Reactions ◽  
First Order ◽  
Kinetics Of

The kinetics of the electron transfer reaction of NADH with 12-tungstocobaltate(III) has been studied over the range 5.07 ≤ 104[NADH] ≤ 15.22 mol dm-3, 7.0 ≤ pH ≤ 8.0 and 20 ≤ t ≤ 35oC in aqueous medium. The electron transfer reaction showed first-order dependence each in [NADH]Tand [12-tungstocobaltate(III)]T. The products of the reaction were found to be NAD+and 12-tungstocobaltate(II). The activation parameters ΔH#(kJ mol-1) and ΔS#(JK-1mol-1) of the electron transfer reactions were found to be 64.4±1.8 and -48.86±6.0. Negative value of ΔS#is an indicative of an ordered transition state for the electron transfer reaction.

scholarly journals Kinetics of the reduction of 4-amino and 4-cyanopyridinechlorocobaloximes by iron(II)

2006 ◽  
Vol 71 (12) ◽  
pp. 1311-1321 ◽  
Author(s):  
A. Dayalan ◽  
C. Revathi
Keyword(s):  
Nmr Spectroscopy ◽  
Protonation Constant ◽  
Protonated Form ◽  
Order Conditions ◽  
Hydrogen Ion ◽  
Ion Concentrations ◽  
First Order ◽  
Ir And Nmr Spectroscopy ◽  
Pseudo First Order ◽  
Kinetics Of

Cobaloximes such as trans[Co(dmgH) 2(Py-NH2)Cl] and trans- [Co(dmgH) 2(Py-CN)Cl], where, dmgH = dimethylglyoximato anion, Py-NH 2 = 4-aminopyiridne and Py-CN = 4-cyanopyridine, were prepared and characterized by elemental analysis, UV-VIS, IR and NMR spectroscopy. The kinetics of iron(II) reduction of the complexes were studied spectrophotometrically at 300 nm in 2% (v/v) DMSO-H2O medium at 27?0.1?C and I = 0.25 M (LiClO4) at various hydrogen ion concentrations in the range 2.5 x 10-4 to 5.0x10-2 M under pseudo-first-order conditions using an excess of the reductant. The inverse dependence of rate on [H+] suggests an equilibrium between the protonated and unportonated forms of the complexes, the protonated form reacting slower than the unprotonated form. Computation of the data enabled the evaluation of the rate constants for the protonated and unprotonated from of the complexes, leading to an evaluation of the protonation constant for the complexes. .

Kinetics and mechanism of dehydrochlorination of N-aryl-C-ethoxycarbonylformohydrazidoyl chlorides

1986 ◽  
Vol 64 (5) ◽  
pp. 871-875 ◽  
Author(s):  
Ahmad S. Shawali ◽  
Hassan A. Albar
Keyword(s):  
Rate Constants ◽  
Water Solution ◽  
Chloride Ion ◽  
Order Conditions ◽  
Rate Law ◽  
First Order ◽  
Rate Determining Step ◽  
Pseudo First Order ◽  
Reaction Constants ◽  
Kinetics Of

The kinetics of triethylamine (TEA) catalyzed deydrochlorination of a series of N-aryl-C-ethoxycarbonylformohydrazidoyl chlorides 1a–m have been studied under pseudo-first-order conditions in 4:1 (v/v) dioxane–water solution at 30 °C. For all compounds studied, the kinetics followed the rate law: kobs = k2 (TEA). The values of the overall second-order rate constants for the studied compounds were correlated by the equation: log k2 = 0.533σ−-0.218. The results are compatible with a mechanism involving a fast reversible deprotonation step leading to the anion of 1, followed by rate-determining step involving the loss of the chloride ion from the anion. The reaction constants of these two steps were estimated to be 0.845 and −0.312, respectively.

scholarly journals Non enzymatic NADH-dependent reduction of Cis-[Co(en)2(H2O)2]3+ in aqueous medium

2018 ◽  
Vol 6 (2) ◽  
pp. 163
Author(s):  
Bharati Behera ◽  
Jashoda Behera
Keyword(s):  
Electron Transfer ◽  
Aqueous Medium ◽  
Transfer Reaction ◽  
Activation Parameters ◽  
Electron Transfer Reaction ◽  
Transfer Reactions ◽  
Electron Transfer Reactions ◽  
First Order ◽  
Order Dependence ◽  
Kinetics Of

The kinetics of the electron transfer reaction of NADH with Cis-[Co(en)2(H2O)2]3+ has been studied over the range 1.0 ≤ 102 [NADH] ≤ 3.0 mol dm-3, 7.0 ≤ pH ≤ 8.0 and 200C ≤ t ≤ 350C in aqueous medium. The rate of electron transfer reaction was found to be first-order dependence each in [NADH]T and Cis-[Co(en)2(H2O)2]3+T. The products of the reaction were found to be NAD+ and Co(II). The corresponding activation parameters of the electron transfer reactions were found to be as ΔH#=27.55 kJ mol-1 and  ΔS#= -189.35 JK-1mol-1. 

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