Measuring and Analyzing Binding Kinetics of Coupled Folding and Binding Reactions Under Pseudo-First-Order Conditions

Author(s):  
Kristine Steen Jensen
1992 ◽  
Vol 70 (10) ◽  
pp. 2515-2519 ◽  
Author(s):  
Sharifa S. Alkaabi ◽  
Ahmad S. Shawali

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.


1981 ◽  
Vol 36 (3) ◽  
pp. 359-361 ◽  
Author(s):  
Thomas Rausch ◽  
Frieder Hofmann ◽  
Willy Hilgenberg

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.


2006 ◽  
Vol 71 (12) ◽  
pp. 1311-1321 ◽  
Author(s):  
A. Dayalan ◽  
C. Revathi

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. .


1986 ◽  
Vol 64 (5) ◽  
pp. 871-875 ◽  
Author(s):  
Ahmad S. Shawali ◽  
Hassan A. Albar

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.


RSC Advances ◽  
2014 ◽  
Vol 4 (99) ◽  
pp. 56068-56073 ◽  
Author(s):  
Karuppiah Nagaraj ◽  
Subramanian Sakthinathan ◽  
Sankaralingam Arunachalam

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.


2002 ◽  
Vol 67 (12) ◽  
pp. 803-808 ◽  
Author(s):  
Fatima Jeyanthi ◽  
G. Vijayakiiinarand ◽  
K.P. Elango

The kinetics of the oxidation of benzaldehyde and para-substituted benzaldehydes by quinolinium chlorochromate in water-dimethylformamide mixtures has been studied under pseudo-first-order conditions at 25?0.2?C. The operation of non-specific and specific solvent-solute interactions was explored by correlating the rate data with solvent parameters through a correlation analysis technique. Both electron-releasing and electron-withdrawing substitutents enhance the rate of oxidation and the Hammett plot shows a break in the reactivity order indicating the applicability of a dual mechanism.


2018 ◽  
Vol 6 (2) ◽  
pp. 71-75
Author(s):  
Larry H Kolopajlo ◽  
Shelby Coleman

The kinetics of the ligand exchange reaction between 2,2’-bipyridine (bipy) and NiNTA- was studied over the pH range 4.7 to 7.5 at 25.0 0C and an ionic strength of 0.10 M by following the formation of Ni(bipy)3 product at 307 nm. All reactions were run under pseudo-first order conditions with a [bipy]/[NiNTA-] ratio of at least 20. The reaction is first-order with respect to each of NiNTA- and to bipy. The reaction is also accelerated by hydrogen ion. The rate constant for the hydrogen ion unassisted addition of bipy to NiNTA- is 0.671 M-1 s-1. The reaction is also first-order in hydrogen ion with a rate constant for the hydrogen ion assisted addition of bipy to NiNTA- is 9.45 x 104 M-2 s-1. A dissociative type mechanism accelerated by hydrogen ion is proposed. The work has significance by showing that NiEDDA and NiNTA, both aminopolyacrboxylate complexes react by the same mechanism.


2007 ◽  
Vol 72 (2) ◽  
pp. 89-100 ◽  
Author(s):  
Milutin Milosavljevic ◽  
Aleksandar Marinkovic ◽  
Boban Cekovic ◽  
Slavica Razic

The reaction kinetics of the synthesis of sodium ethyl xanthogeneacetate from potassium ethylxanthogenate and sodium chloroacetate in distilled water as the reaction medium at 25, 30, 35 and 40?C, were investigated. The obtained reaction mixture was a complex system which demanded the use of two methods for the kinetic measurements. The reaction was followed using the conductrometric and UV/Vis spectrophotometric method with equimolar initial concentrations of the reactants and under pseudo-first order conditions with respect to one of the reactants. The rate constants of the pseudo-first order and second order reactions were calculated from the data. On the basis of the reaction constants, the activation parameters were calculated and are discussed. .


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohamed S. Yahia ◽  
Ahmed S. Elzaref ◽  
Magdy B. Awad ◽  
Ahmed M. Tony ◽  
Ahmed S. Elfeky

Abstract Commercial Granulated Active Carbon (GAC) has been modified using 10 Gy dose Gamma irradiation (GAC10 Gy) for increasing its ability of air purification. Both, the raw and treated samples were applied for removing Chlorpyrifos pesticide (CPF) from ambient midair. Physicochemical properties of the two materials were characterized by Fourier Transform Infrared (FT-IR) and Raman spectroscopy. The phase formation and microstructure were monitored using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), supported with Energy-Dispersive X-ray (EDX). The Surface area measurement was detected using BET particle size prosometry. Obtained outcomes showed that, the maximum adsorption capacity, given by Langmuir equations, was greatly increased from 172.712 to 272.480 mg/g for GAC and GAC10 Gy, respectively, with high selectivity. The overall removal efficiency of GAC10 Gy was notably comparable to that of the original GAC-sorbent. The present study indicated that, gamma irradiation could be a promising technique for treating GAC and turned it more active in eliminating the pesticides pollutants from surrounding air. The data of equilibrium has been analyzed by Langmuir and Freundlich models, that were considerably better suited for the investigated materials than other models. The process kinetics of CPF adsorbed onto both tested carbon versions were found to obey the pseudo first order at all concentrations with an exception at 70 mg/l using GAC, where, the spontaneous exothermic adsorption of Chlorpyrifos is a strong function for the pseudo-first order (PFO) and pseudo second order (PSO) kinetics.


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