Kinetics of Ion-Pair Effect of Aquation of Bromopentaammine Cobalt(III) Complex in Different Dicarboxylate Media

2011 ◽  
Vol 324 ◽  
pp. 166-169 ◽  
Author(s):  
Farah Zeitouni ◽  
Gehan El-Subruiti ◽  
Ghassan Younes ◽  
Mohammad Amira
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Compensation Effect ◽  
Ion Pairing ◽  
Reaction Rates ◽  
Ion Pair ◽  
Free Energy Of Activation ◽  
Different Types ◽  
Different Temperatures ◽  
Kinetics Of

The rate of aquation of bromopentaammine cobalt(III) ion in the presence of different types of dicarboxylate solutions containing tert-butanol (40% V/V) have been measured spectrophotometrically at different temperatures (30-600°C) in the light of the effects of ion-pairing on reaction rates and mechanism. The thermodynamic and extrathermodynamic parameters of activation have been calculated and discussed in terms of solvent effect on the ion-pair aquation reaction. The free energy of activation ∆Gip* is more or less linearly varied among the studied dicarboxylate ion-pairing ligands indicating the presence of compensation effect between ∆Hip* and ∆Sip*. Comparing the kip values with respect of different buffers at 40% of ter-butanol is introduced.

scholarly journals Reactivity of Phenol and Aniline towards Quinolinium Chloro Chromate: A Comparative Oxidation Kinetic Study

2015 ◽  
Vol 59 ◽  
pp. 81-92
Author(s):  
Seplapatty Kalimuthu Periyasamy ◽  
H. Satham Hussain ◽  
R. Manikandan
Keyword(s):  
Oxidation Kinetic ◽  
Activation Parameters ◽  
Dipole Interaction ◽  
Reaction Rates ◽  
Hydrogen Ion ◽  
Aqueous Acetic Acid ◽  
Acetic Acid Medium ◽  
First Order ◽  
Different Temperatures ◽  
Kinetics Of

The kinetics of Oxidation of Phenol and aniline by quinolinium Chlorochromate (QCC) in aqueous acetic acid medium leads to the formation of quinone and azobenzene respectively. The reactions are first order with respect to both Phenol and aniline. The reaction is first order with respect to quinolinium chlorochromate (QCC) and is catalyzed by hydrogen ion. The hydrogen-ion dependence has the form: kobs = a+b [H+]. The rate of oxidation decreases with increasing dielectric constant of solvent, indicating the presence of an ion-dipole interaction. The reaction does not induced the polymerization of acrylonitrile. The retardation of the rate by the addition of Mn2+ ions confirms that a two electron transfer process is involved in the reaction. The reaction rates have been determined at different temperatures and the activation parameters have been calculated. From the above observations kinetic results a probable mechanism have been proposed.

scholarly journals Effect of excess free energy of solvents on the oxidation of methionine by quinolinium fluorochromate: A kinetic study

2008 ◽  
Vol 73 (7) ◽  
pp. 735-744 ◽  
Author(s):  
D.S. Bhuvaneshwari ◽  
K.P. Elango
Keyword(s):  
Free Energy ◽  
Excess Free Energy ◽  
Activation Parameters ◽  
Chloroacetic Acid ◽  
Reaction Rates ◽  
Solvent Mixtures ◽  
Free Energy Function ◽  
Different Temperatures ◽  
Oxidation Of Methionine ◽  
Quinolinium Fluorochromate

The oxidation of methionine by quinolinium fluorochromate (QFC) was studied in the presence of chloroacetic acid, in water/organic solvent mixtures of varying excess molar free energy function. The reaction is first order with respect to both QFC and acid. The reaction rates were determined at different temperatures and the activation parameters computed. The rate data was correlated with different solvent parameters using linear multiple regression analysis. From the results, information on the solvent-reactants and the solvent-transition state interactions was obtained. .

scholarly journals Enzymatic Kinetic Issues and Controversies Surrounding Gibbs Free Energy of Activation and Arrhenius Activation Energy

2020 ◽  
pp. 1-13
Author(s):  
Ikechukwu I. Udema ◽  
Abraham Olalere Onigbinde
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Theoretical Research ◽  
Energy Of Activation ◽  
Arrhenius Activation Energy ◽  
Free Energy Of Activation ◽  
Different Temperatures ◽  
The Difference

Background: The equation of the difference between reverse and forward Gibbs free energy of activation (ΔΔGES#) reflects Michaelis-Menten constant (KM) in both directions; this may not be applicable to all enzymes even if the reverse reaction is speculatively Michaelian. Arrhenius activation energy, Ea and (Ea - ΔGES#)/RT) are considered = ΔGES# and KM respectively. The equations are considered unlikely. Objectives: The objectives of this research are: 1) To derive what is considered as an appropriate equation for the determination of the difference in ΔGES# between the reverse and forward directions, 2) calculate the difference between the reverse and total forward ΔGES#, and 3) show reasons why Ea ≠ ΔGES#  in all cases. Methods: A major theoretical research and experimentation using Bernfeld method. Results and Discussion: A dimensionless equilibrium constant KES is given. Expectedly, the rate constants were higher at higher temperatures and the free energy of activation with salt was < the Arrhenius activation energy, Ea; ΔΔGES#ranges between 67 - 68 kJ/mol. Conclusion: The equations for the calculation of the difference in free energy of activation (ΔΔGES#) between the forward and reverse directions and a dimensionless equilibrium constant for the formation of enzyme-substrate (ES) were derivable. The large positive value of the ΔΔGES# shows that the forward reaction is not substantially spontaneous; this is due perhaps, to the nature of substrate. The equality of Arrhenius activation energy (Ea) and ΔGES# may not be ruled out completely but it must not always be the case; the presence of additive like salt can increase the magnitude of Ea well above the values of the ΔGES#. A dimensionless equilibrium constant for the net yield of ES seems to be a better alternative than KM. The Ea unlike ΔGES#  requires at least two different temperatures for its calculation.

Kinetics and mechanism of oxidation of nickel(II) tetraazamacrocycles by the peroxydisulphate anion in aqueous and binary aqueous mixtures

1992 ◽  
Vol 70 (11) ◽  
pp. 2785-2791 ◽  
Author(s):  
Robert I. Haines ◽  
Sandra J. Northcott
Keyword(s):  
Rate Constants ◽  
Metal Ion ◽  
Ion Pairing ◽  
Ion Pair ◽  
Aqueous Mixtures ◽  
Kinetics Of Oxidation ◽  
Steric Factors ◽  
Temperature Dependences ◽  
Mechanism Of Oxidation ◽  
Kinetics Of

The kinetics of oxidation of several nickel(II) tetraazamacrocycles by the peroxydisulphate anion have been studied in water and in binary aqueous mixtures. The reactions proceed via an ion-pairing pre-equilibrium, followed by metal ion-assisted peroxy-bond fissure within the ion-pair solvent shell. The derived rate law is[Formula: see text]Ion-pairing constants have been determined and have been found to be little influenced by steric factors, but do depend on solvent composition. Rate constants have been extracted using the rate expression and activation energies have been estimated from temperature dependences.

scholarly journals Synthesis of new series of Pyrazoline, and study their Kinetics and Reaction Mechanism

2019 ◽  
Vol 7 (2) ◽  
pp. 5-13
Author(s):  
Kosrat N. Kaka ◽  
Salam G. Taher ◽  
Wali M. Hamad ◽  
Aram H. Ibrahim
Keyword(s):  
Free Energy ◽  
Reaction Mechanism ◽  
Thermodynamic Parameters ◽  
Compensation Effect ◽  
New Products ◽  
Order Reaction ◽  
Membered Ring ◽  
Free Energies ◽  
First Order ◽  
Kinetics Of

A new series of novel pyrazoline compounds were synthesized by addition of thiosemicarbazide to the 2,6-dibenzylidenecyclohexanone (Chalcone) and its para substituted derivatives. This study was conducted for four purposes. Firstly, a series of five membered ring pyrazoline compounds were synthesized and the structure of all new products obtained are supported by spectral data (1H-NMR, 13CNMR, IR and UV-Vis.), and the effect of substituents were studied. Secondly, the reaction kinetics of the new synthesized compounds were studied to investigate the reaction mechanism pathway and order of the reaction; it was found that, the reaction undergoes via Claisen route of mechanism with first-order reaction. Thirdly, the thermodynamics of the reaction were studied, the rate of the reaction, Arrhenius parameters (A), and thermodynamic parameters for activation includes (free energies (Ea), entropies (ΔS#), and Gibbs free energy (ΔG#) were estimated. Finally, the compensation effect was also studied, and found the same pathway for all of the synthesized pyrazoline compounds.

Acid dependence and ion pairing in the anation reactions yielding iron(III) monosulfate

1970 ◽  
Vol 48 (19) ◽  
pp. 3100-3103 ◽  
Author(s):  
F. L. Baker ◽  
W. MacF. Smith
Keyword(s):  
Rate Constant ◽  
Ion Pairing ◽  
Ion Pair ◽  
Pair Formation ◽  
Association Constants ◽  
Stopped Flow ◽  
Ion Pair Formation ◽  
Significant Dependence ◽  
Kinetics Of ◽  
Acid Dependence

Stopped-flow studies of the kinetics of the a nation reaction yielding iron(III) monosulfate indicate a significant dependence of rate constant on acidity and also a dependence on iron concentrations. This is consistent with association constants for outer ion pair formation between the reactants which have about three times the Fuoss values.

Kinetics of Oxidation of Benzaldehydes by Quinolinium Dichromate

2003 ◽  
Vol 58 (12) ◽  
pp. 1201-1205 ◽  
Author(s):  
Hesham A. A. Medien
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Water Medium ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Different Temperatures ◽  
Acetic Acid Water ◽  
Kinetics Of

Quinolinium dichromate (QDC) in sulfuric acid oxidizes benzaldehydes to the corresponding acids in a 50% (v/v) acetic acid-water medium. The reaction is first order each in [QDC], [substrate] and [H+]. The reaction rates have been determined at different temperatures and the activation parameters calculated. The rate decreases with an increase in the water content of the medium. The effects of substituents have been studied. A suitable mechanism is proposed.

Modelling Size-Selected Growth of Nanodots by Using Reaction Kinetic Approach

2006 ◽  
Vol 959 ◽  
Author(s):  
Kirsi Nevalainen ◽  
Marko Rusanen ◽  
Ismo T. Koponen
Keyword(s):  
Free Energy ◽  
Size Distribution ◽  
Metastable State ◽  
Continuum Model ◽  
Reaction Kinetic ◽  
Reaction Rates ◽  
Size Selection ◽  
Size Dependent ◽  
Kinetics Of ◽  
Selection Of

ABSTRACTThe size selection of nanodots during the growth is modelled by using the reaction kinetic model with reaction rates for dot size dependent attachment and detachment processes, related to the free energy of dots. Long-lived metastable state is found near the minimum of free energy, but the kinetics of the growth causes the peak to overshoot the location of minimum of the energy. The size distribution of dots is shown to be nearly Gaussian with minor skewness originated from kinetics. However, it is argued that this skewness is inherently related to the effect of overshooting, and thus to the formation of the long lived metastable state with size selected nanodots. Based on RKM, a simple continuum model is derived to describe the size selection and narrowing of the size distribution.

scholarly journals Kinetics and Mechanism of Oxidation of Aromatic Aldehydes by Imidazolium Dichromate in Aqueous Acetic Acid Medium

2009 ◽  
Vol 6 (s1) ◽  
pp. 522-528 ◽  
Author(s):  
S. Sheik Mansoor ◽  
S. Syed Shafi
Keyword(s):  
Acetic Acid ◽  
Acid Medium ◽  
Activation Parameters ◽  
Aromatic Aldehydes ◽  
Reaction Rates ◽  
Aqueous Acetic Acid ◽  
Acetic Acid Medium ◽  
Kinetics Of Oxidation ◽  
Different Temperatures ◽  
Kinetics Of

The kinetics of oxidation of benzaldehyde (BA) andpara-substituted benzaldehydes by imidazolium dichromate (IDC) has been studied in aqueous acetic acid medium in the presence of perchloric acid. The reaction is first order each in [IDC], [Substrate] and [H+]. The reaction rates have been determined at different temperatures and the activation parameters calculated. Electron withdrawing substituents are found to increase the reaction and electron releasing substituents are found to retard the rate of the reaction and the rate data obey the Hammett relationship. The products of the oxidation are the corresponding acids. The rate decreases with the increase in the water content of the medium. A suitable mechanism is proposed.

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