Kinetics of Environmental Averaging, and the Stereochemistry of (CH3)ClGe(C5H7O2)2. A Case of a Second Order Kinetic Process

1975 ◽  
Vol 53 (3) ◽  
pp. 448-454 ◽  
Author(s):  
Ken A. Hersh ◽  
Nick Serpone
Keyword(s):  
Activation Parameters ◽  
Second Order ◽  
Bond Rupture ◽  
Methyl Groups ◽  
Order Kinetic ◽  
Line Broadening ◽  
Ring Proton ◽  
Kinetics Of ◽  
Oxygen Bond ◽  
Proper Orientation

Dynamic n.m.r. studies on the stereochemistry of (CH3)ClGe(C5H7O2)2 (acac = C5H7O2−), indicate that the complex adopts the cis configuration in CDCl3–CCl4 solutions. Kinetics of environmental averaging of the acac ring proton (—CH=) and acac methyl groups between the respective nonequivalent sites in the C1 isomer have been investigated in the temperature range −31.0 to 23.1° by line-broadening techniques. Kinetics of the averaging process are second order in complex concentration. Activation parameters are: Ea = 6.0 ± 0.3 kcal/mol, ΔS≠ = −30 ± 1 e.u., and k25 = 1.6 × 102 M−1 S−1. Rearrangements are viewed as occurring via a germanium–oxygen bond rupture as a first step to yield a five-coordinate intermediate. The rate-determining sequence is thought to involve proper orientation of two five-coordinate species prior to formation of a bis-acac bridged dimer.

scholarly journals KINETICS OF OZONE REACTIONS WITH ADENINE AND CYTOSINE IN AQUEOUS SOLUTIONS

2020 ◽  
Vol 63 (10) ◽  
pp. 17-22
Author(s):  
Aigul A. Maksyutova ◽  
Elvina R. Khaynasova ◽  
Yuriy S. Zimin
Keyword(s):  
Aqueous Solutions ◽  
Rate Constants ◽  
Correlation Coefficients ◽  
Activation Parameters ◽  
Second Order ◽  
Order Kinetic ◽  
Temperature Dependences ◽  
Ozone Reactivity ◽  
Kinetics Of ◽  
Ozone Reactions

The ultraviolet spectroscopy method has been applied to study the kinetics of the ozone reactions with nitrogenous bases (NB), namely adenine and cytosine in aqueous solutions. At the first research stage, the range of NB working concentrations has been determined. It was found that linear dependences between optical densities and concentrations of nitrogenous bases aqueous solutions are quite reliable, with correlation coefficients r ≥ 0.998, are satisfied up to [NB] = 2.3 ∙ 10–4 mol/l. According to the Bouguer-Lambert-Beer law, adenine and cytosine extinction coefficients in aqueous solutions were determined and subsequently used to calculate their residual concentrations. At the next stage, the kinetics of nitrogenous bases ozonized oxidation was studied with equal initial concentrations of the starting substances ([NB]0 = [О3]0). The results revealed that the kinetic consumption curves of the starting reagents are fairly well linearized (r ≥ 0.996) in the second-order reaction equation coordinates. As found with the bubbling installation, 1 mol of the absorbed ozone falls on 1 mol of the used NB. Thus, the reactions of ozone with adenine and cytosine explicitly proceed according to the second-order kinetic laws (the first – according to О3 and the first – according to NB). The rate constants were calculated by the integral reaction equations, the values of which indicate a higher ozone reactivity in relation to nitrogen bases. The temperature dependences of the second-order rate constants was studied ranging 285-309 K, and the activation parameters (pre-exponential factors and activation energies) of the ozone reactions with adenine and cytosine in aqueous solutions were determined.

scholarly journals Kinetics of scandium recovery by TVEX-TBP from the solution formed after the salt chlorinator cake leaching

2020 ◽  
Vol 168 ◽  
pp. 00050
Author(s):  
Vadym Korovin ◽  
Yurii Pohorielov ◽  
Yurii Shestak ◽  
Oleksandr Valiaiev ◽  
Jose Luis Cortina
Keyword(s):  
Chemical Interaction ◽  
Extraction Process ◽  
Second Order ◽  
Order Kinetic ◽  
Order Model ◽  
Elovich Equation ◽  
Diffusion Phase ◽  
Leaching Solution ◽  
Pseudo Second Order ◽  
Kinetics Of

Kinetics of scandium recovery by TVEX containing tributyl phosphate was studied from the clarified leaching solution of salt chlorinator cake. To assess the contribution of each diffusion phase, experimental data were analyzed using a graphic method. To define the contribution of chemical interaction into the scandium extraction process, recovery kinetics was quantitatively described using pseudo-first order, pseudo-second order kinetic models and Elovich equation in linearized form. It was established that recovery kinetics was most accurately described with the pseudo-second-order model.

Kinetics of the hydrolysis of acyl chlorides in pure water

1967 ◽  
Vol 45 (14) ◽  
pp. 1619-1629 ◽  
Author(s):  
A. Queen
Keyword(s):  
Pure Water ◽  
Activation Parameters ◽  
Acyl Chlorides ◽  
Reversible Addition ◽  
Electron Donation ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Chlorine Bond ◽  
Oxygen Bond ◽  
Bimolecular Mechanism

The activation parameters ΔH≠, ΔS≠, and ΔCP≠ for the hydrolyses of a series of alkyl chloroformates and dimethylcarbamyl chloride in water have been determined. The results indicate that, with increasing electron donation to the chlorocarbonyl group, the mechanism changes from bimolecular to unimolecular (SN1) displacement at this position. For isopropyl chloroformate, some concurrent alkyl–oxygen bond fission is also indicated. The bimolecular mechanism involves reversible addition of water to the carbonyl group followed by ionization of the carbon–chlorine bond.

Adsorption Kinetics of Reactive Dyes on Silk with Octyl Butyl Dimethyl Ammonium Bromide as Accelerant

2012 ◽  
Vol 549 ◽  
pp. 278-282 ◽  
Author(s):  
Cheng Chen ◽  
Guang Xian Zhang ◽  
Feng Xiu Zhang ◽  
Hui Zheng
Keyword(s):  
Adsorption Kinetics ◽  
Dye Adsorption ◽  
Reactive Dyes ◽  
Second Order ◽  
Ammonium Bromide ◽  
Order Kinetic ◽  
Dye Uptake ◽  
Dimethyl Ammonium ◽  
Adsorption Rates ◽  
Kinetics Of

With octyl butyl dimethyl ammonium bromide (OBDAB) as accelerant, adsorption kinetics of dyeing silk with three reactive dyes was studied in this paper. As concentration of OBDAB increased, the dye-uptake rate increased. The highest dye-uptake rates of three reactive dyes could reach to 89.40%~98.98% and the concentration of OBDAB was only 6-8g/L. This showed OBDAB was an effective accelerant. Pseudo first- and second-order kinetic models were used to analyze the adsorption kinetic data. The experimental data were found to follow the second-order kinetic model. Meanwhile, the initial dye adsorption rates of reactive red dye B-3BF, reactive yellow dye B-4RFN and reactive orange dye B-2RLN increased as temperature increased, and the activation energy of them were found respectively to be 28.42,13.14,32.90 kJ/mol.The positive values of and obtained indicated that reactive dyes adsorption with OBDAB as accelerant was an endothermic process. The conclusion showed OBDAB was a potential accelerant.

Cleavage of the Sulfur–Sulfur Bond in 2,4-Dinitrophenyl-4-substituted-phenyl Disulfides by trans-[IrCl(CO) (PPh3)2]. A Kinetic Study

1973 ◽  
Vol 51 (22) ◽  
pp. 3790-3794 ◽  
Author(s):  
Chiu T. Lam ◽  
Caesar V. Senoff
Keyword(s):  
Transition State ◽  
Kinetic Study ◽  
Sulfur Atom ◽  
Activation Parameters ◽  
Initial Step ◽  
Second Order ◽  
Nucleophilic Attack ◽  
Kinetics Of ◽  
Sulfur Bond

The kinetics of the reaction between trans-[IrCl(CO)(PPh3)2] and a series of 2,4-dinitrophenyl-4-substituted-phenyl disulfides, YC6H4SSC6H3(NO2)2 (Y = Br, F, H, CH3, or CH3O) have been investigated in toluene between 70 and 90°. These reactions were found to follow simple second order kinetics, rate = k2[IrCl(CO)(PPh3)2][YC6H4SSC6H3(NO2)2]. The rates of reaction were also found to be insensitive to the nature of the para substituent, Y. This fact together with the observed activation parameters, ΔH≠ ~ 17 kcal mol−1 and ΔS≠ ~ − 19 cal mol−1 deg−1, have been interpreted as indicating that the initial step in these reactions involves a nucleophilic attack by the iridium atom at the sulfur atom bonded to the 2,4-dinitrophenyl group, followed by the formation of a three-centered transition state. An overall mechanism for these reactions is presented and discussed.

Kinetik der Reaktion von Papain mit Bromacetamid / Kinetics of the reaction of papain with bromoacetamide

1971 ◽  
Vol 26 (1) ◽  
pp. 43-46 ◽  
Author(s):  
Hans-Gerhard Löffler ◽  
Friedhelm Schneider ◽  
Helmut Wenck
Keyword(s):  
Rate Constants ◽  
Turning Point ◽  
Ph Dependence ◽  
Activation Parameters ◽  
Second Order ◽  
Order Rate ◽  
Ph Range ◽  
Kinetics Of

The pH-dependence of the second order rate constants of the reaction of papain with bromoacetamide in the pH-range 5,5-8,5 is described by a curve with a turning point corresponding to a pK 7,3 ± 0,1 at 25°. This is the pK of a catalytically essential imidazole residue. The activation parameters of the reaction of papain with bromoacetamide were determined. The second order rate constants at pH 7 for the reaction is 200 times greater than for the reaction of bromoacetamide with simple SH-compounds.

Kinetics and mechanism of bromination of styrenes

1967 ◽  
Vol 45 (2) ◽  
pp. 167-173 ◽  
Author(s):  
Keith Yates ◽  
W. V. Wright
Keyword(s):  
Activation Parameters ◽  
Second Order ◽  
Linear Free Energy Relationship ◽  
Reaction Products ◽  
Order Process ◽  
Third Order ◽  
Linear Free Energy ◽  
Reaction Constant ◽  
Relationship Of ◽  
Kinetics Of

The kinetics of bromination of six substituted styrènes (3-fluoro-, 3-chloro-, 3-bromo-, 3,4-dichloro-, 3-nitro-, and 4-nitro-) in anhydrous acetic acid have been investigated at several temperatures. At 25.3 °C the reactions follow the rate expression [Formula: see text]The rate constants for the second order process show a good linear free energy relationship of the log k versus σ type with ρ = − 2.24. (The value obtained at 35.3 °C is − 1.93.) No simple rate-substituent dependence is obtained for the more complex third order process. Activation parameters have been obtained for the second order brominations, the ΔS≠ values being large and negative. Bromination of styrene in the presence of a large excess of acetate or nitrate gives only two products in each case, the α,β-dibromide and the α –acetoxy β-bromide or α -nitrato- β -bromide respectively.The magnitude of the reaction constant ρ, the values of ΔS≠, and the reaction products all support a mechanism involving a highly unsymmetrical bromonium ion intermediate.

scholarly journals Recombination of Poly(Acrylic Acid) Radicals in Acidic Aqueous Solutions: A Pulse Radiolysis Study

2021 ◽  
Vol 11 (21) ◽  
pp. 10142
Author(s):  
Małgorzata Matusiak ◽  
Sławomir Kadłubowski ◽  
Piotr Ulański
Keyword(s):  
Acrylic Acid ◽  
Aqueous Solutions ◽  
Ph Dependence ◽  
Polymer Concentration ◽  
Second Order ◽  
Order Kinetic ◽  
Initial Number ◽  
Linear Charge Density ◽  
Kinetics Of ◽  
Poly Acrylic Acid

Carbon-centered radicals have been randomly generated on the chains of poly(acrylic acid), PAA, the simplest synthetic anionic polyelectrolyte, by pulse-irradiating its dilute, oxygen-free aqueous solutions by 6 MeV electron beam. In some experiments, oligo(acrylic acid), OAA, and propionic acid, PA, were used as PAA models. Recombination kinetics of PAA radicals has been followed by fast spectrophotometry. A strong pH dependence of radical lifetime on pH, and thus on the linear charge density due to deprotonated carboxylate groups, has been confirmed, while a weaker amplitude of pH dependence was observed for OAA and PA. Decay kinetics of PAA radicals in the protonated state, at pH 2, have been studied in some detail. At moderate doses of ionizing radiation, resulting in a moderate average initial number of radicals per chain, ZR0, the decay can be satisfactorily described by a second-order kinetic model, but a somewhat better fit is obtained by using a dispersive kinetics approach. While for a constant polymer concentration the reciprocal half-lives are proportional to the initial radical concentrations, such a data series for different PAA concentrations do not overlap, indicating that the overall radical concentration is not the decisive factor controlling the kinetics. Arranging all data, in the form of second-order rate constants, as a function of the average initial number of radicals per chain allows one to obtain a common dependence. The latter seems to consist of two parts: a horizontal one at low ZR0 and another one of positive slope at higher ZR0. This is interpreted as two kinetic regimes where two distinct reactions dominate, intermolecular and intramolecular recombination, respectively. Comparison of the low ZR0 data with calculations based on the translational diffusion model indicate that the latter is not the rate-controlling process in intermolecular recombination of polymer radicals; segmental diffusion is the more likely candidate.

scholarly journals Potential Biosorbent Derived fromCalligonum polygonoidesfor Removal of Methylene Blue Dye from Aqueous Solution

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Asma Nasrullah ◽  
Hizbullah Khan ◽  
Amir Sada Khan ◽  
Zakaria Man ◽  
Nawshad Muhammad ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Particle Size ◽  
Second Order ◽  
Blue Dye ◽  
Order Kinetic ◽  
Particle Size Analyzer ◽  
Initial Ph ◽  
Pseudo Second Order ◽  
Kinetics Of

The ash ofC. polygonoides(locally called balanza) was collected from Lakki Marwat, Khyber Pakhtunkhwa, Pakistan, and was utilized as biosorbent for methylene blue (MB) removal from aqueous solution. The ash was used as biosorbent without any physical or chemical treatment. The biosorbent was characterized by using various techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The particle size and surface area were measured using particle size analyzer and Brunauer-Emmett-Teller equation (BET), respectively. The SEM and BET results expressed that the adsorbent has porous nature. Effects of various conditions such as initial concentration of methylene blue (MB), initial pH, contact time, dosage of biosorbent, and stirring rate were also investigated for the adsorption process. The rate of the adsorption of MB on biomass sample was fast, and equilibrium has been achieved within 1 hour. The kinetics of MB adsorption on biosorbent was studied by pseudo-first- and pseudo-second-order kinetic models and the pseudo-second-order has better mathematical fit with correlation coefficient value (R2) of 0.999. The study revealed thatC. polygonoidesash proved to be an effective, alternative, inexpensive, and environmentally benign biosorbent for MB removal from aqueous solution.

Kinetics of Monochloramine Decay in Model and Distribution System Waters

2011 ◽  
Vol 183-185 ◽  
pp. 834-838 ◽  
Author(s):  
Shao Gang Liu ◽  
Chen Feng Fan ◽  
Zhi Liang Zhu
Keyword(s):  
Decay Rate ◽  
Distribution System ◽  
Distribution Systems ◽  
Ph Value ◽  
Second Order ◽  
Order Kinetic ◽  
Nitrite Ion ◽  
Experimental Conditions ◽  
Order Kinetic Model ◽  
Kinetics Of

The model of second-order reaction kinetics has been used to stimulate the monochloramine decay in model and distribution system waters by nonlinear fit. Several factors were investigated, including pH, bromide, nitrite concentrations in this system. The results showed that pH value was an important factor on the monochloramine decay rate, especially when pH was below 7.0. Presence of bromide ions had different impact under experimental conditions However, when pH was above 7.60, 0.1 mg/L concentration of bromide affect hardly the decay rate of mononchloramine. The results demonstrated that the second-order kinetic model could fit well the experimental results of monochloramine decay reaction under the conditions of bromide, and nitrite ion. Finally, the work presented here validates and extends this model for use in distribution systems under realistic chloramination conditions.

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