scholarly journals OXIDATION OF THE ACRYDINE BY PEROXYDECANIC ACID IN VARIOUS ORGANIC SOLVENTS

2020 ◽  
Vol 2020 (60) ◽  
pp. 22-30
Author(s):  
Volodymyr DUTKA ◽  
◽  
Galyna MIDYANA ◽  
Yuriy DUTKA ◽  
Olena PAL’CHIKOVA ◽  
...  
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Molar Volume ◽  
Organic Solvents ◽  
Rate Constants ◽  
Physicochemical Parameters ◽  
Oxidation Process ◽  
Correlation Equation ◽  
Effective Rate ◽  
Correlation Equations

The rate of oxidation reaction of the acrydine with peroxydecanoic acid in various organic solvents was studied. It has been found the effective rate constants (k) and the activation energy (Ea) of studied process. Between the parameters of the transition state ΔН≠ and ΔЅ≠ is some linear relationship, indicating on the presence of the counteraction effect in our series of experiments. The rate of oxidation and activation energy inflation of solvation peroxyacid and acrydine was calculated. The reaction medium affects the rate of oxidation. Correlation equations between the rate constants of the reactions in study and the physicochemical parameters of the solvents were proposed. The correlation equation for effective rate constants and the basic physicochemical parameters of solvents at 318 K has the form: k = –388.8034 + (1662.9800 ± 313.4735)f(n) – (221.2833 ± 70.3626)f(ε) + (0.8092 ± 0.1145)B N = 8; R = 0.9982; S = 3.0727; F = 5.2713. The polarizability, polarization and basicity, of solvent have effect on the oxidation process. The influence of electrophilicity polarization and molar volume on the rate of oxidation of acrydine decay process is negligible. Correlation equations for effective rate constants for other temperatures are similar. The correlation equation for effective energies (Ea) of activation and the basic physicochemical parameters of solvents has the form: Eа = 104.6924 + (50.3320 ± 12.6429)f(ε) + (0.0557 ± 0.0137)B – (0.1201 ± 0.0188)δ2 – (0.5573 ± 0.0782)Vм N = 9; R = 0.9663; S = 2.8058; F = 1.3842. The polarizability, basicity, molar volume and Hildebrand's function of solvent have effect on the energy of activation process. The proposed correlation equations relate the parameters of the transition state of the oxidation process and the physic-chemical parameters of solvents.

The thermal decompositions of carbamates. II. Methyl N-methylcarbamate

1972 ◽  
Vol 25 (7) ◽  
pp. 1453 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Gas Phase ◽  
Rate Constants ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
Phase Reaction ◽  
Methyl Isocyanate ◽  
Gas Phase Reaction ◽  
First Order

Methyl N-methyloarbamate decomposes in the range 370-422� to give methyl isocyanate and methanol. The reaction is first order in carbamate, and the variation of the rate constants with temperature is given by the equation. k = 1012.39 exp(-4806O/RT) (s-l; activation energy in cal mol-l) Rate constants are unaffected by the addition of isobutene or by increase in the surface to volume ratio of the reaction vessel. The addition of alcohols or amines does not reverse the process. The decomposition is considered to be a homogeneous, unimolecular gas-phase reaction, probably proceeding through a four-centred transition state.

Microscopic Interpretation of Arrhenius Parameters

2018 ◽  
Author(s):  
Niels Engholm Henriksen ◽  
Flemming Yssing Hansen
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Transition State Theory ◽  
Average Energy ◽  
Zero Point ◽  
State Theory ◽  
Exponential Factor ◽  
Quantum Tunnelling ◽  
Microscopic Interpretation ◽  
The Difference

This chapter reviews the microscopic interpretation of the pre-exponential factor and the activation energy in rate constant expressions of the Arrhenius form. The pre-exponential factor of apparent unimolecular reactions is, roughly, expected to be of the order of a vibrational frequency, whereas the pre-exponential factor of bimolecular reactions, roughly, is related to the number of collisions per unit time and per unit volume. The activation energy of an elementary reaction can be interpreted as the average energy of the molecules that react minus the average energy of the reactants. Specializing to conventional transition-state theory, the activation energy is related to the classical barrier height of the potential energy surface plus the difference in zero-point energies and average internal energies between the activated complex and the reactants. When quantum tunnelling is included in transition-state theory, the activation energy is reduced, compared to the interpretation given in conventional transition-state theory.

Kinetic Model of the 1,2-Propanediol Oxidation Reaction in the Presence of 3wt%Pd/α-Al2O3 Catalyst

2021 ◽  
Vol 903 ◽  
pp. 143-148
Author(s):  
Svetlana Cornaja ◽  
Svetlana Zhizhkuna ◽  
Jevgenija Vladiko
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Kinetic Model ◽  
Catalytic Oxidation ◽  
Molecular Oxygen ◽  
Oxidation Reaction ◽  
Main Product ◽  
Oxidation Process ◽  
Water Solution ◽  
Reaction Conditions

Supported 3wt%Pd/α-Al₂O₃ catalyst was tested in selective oxidation of 1,2-propanediol by molecular oxygen. It was found that the catalyst is active in an alkaline water solution. Lactic acid was obtained as the main product of the reaction. Influence of different reaction conditions on 1,2-PDO conversion and oxidation process selectivity was studied. Partial kinetic orders of the reaction with respect to 1,2-propanediol, c0(NaOH), p(O2), n(1,2-PDO)/n(Pd)) were determined and an experimental kinetic model of the catalytic oxidation reaction was obtained. Activation energy of the process was calculated and was found to be about 53 ± 5 kJ/mol.

Effect of Medium on Reactivity for Alkaline Hydrolysis of p-Nitrophenyl Acetate and S-p-Nitrophenyl Thioacetate in DMSO-H2O Mixtures of Varying Compositions: Ground State and Transition State Contributions

2021 ◽  
Author(s):  
Ik-Hwan Um ◽  
Seungjae Kim
Keyword(s):  
Transition State ◽  
Alkaline Hydrolysis ◽  
Ground State ◽  
Rate Constants ◽  
Kinetic Data ◽  
Reaction Medium ◽  
Stepwise Mechanism ◽  
Rate Determining Step ◽  
Leaving Group ◽  
Hydrolysis Of

Second-order rate constants (kN) for reactions of p-nitrophenyl acetate (1) and S-p-nitrophenyl thioacetate (2) with OH‒ have been measured spectrophotometrically in DMSO-H2O mixtures of varying compositions at 25.0 ± 0.1 oC. The kN value increases from 11.6 to 32,800 M‒1s‒1 for the reactions of 1 and from 5.90 to 190,000 M‒1s‒1 for those of 2 as the reaction medium changes from H2O to 80 mol % DMSO, indicating that the effect of medium on reactivity is more remarkable for the reactions of 2 than for those of 1. Although 2 possesses a better leaving group than 1, the former is less reactive than the latter by a factor of 2 in H2O. This implies that expulsion of the leaving group is not advanced in the rate-determining transition state (TS), i.e., the reactions of 1 and 2 with OH‒ proceed through a stepwise mechanism, in which expulsion of the leaving group from the addition intermediate occurs after the rate-determining step (RDS). Addition of DMSO to H2O would destabilize OH‒ through electronic repulsion between the anion and the negative-dipole end in DMSO. However, destabilization of OH‒ in the ground state (GS) is not solely responsible for the remarkably enhanced reactivity upon addition of DMSO to the medium. The effect of medium on reactivity has been dissected into the GS and TS contributions through combination of the kinetic data with the transfer enthalpies (ΔΔHtr) from H2O to DMSO-H2O mixtures for OH‒ ion.

scholarly journals Metal Enolates – Enamines – Enol Ethers: How Do Enolate Equivalents Differ in Nucleophilic Reactivity?

Synthesis ◽  
2019 ◽  
Vol 51 (05) ◽  
pp. 1157-1170 ◽  
Author(s):  
Artem Leonov ◽  
Daria Timofeeva ◽  
Armin Ofial ◽  
Herbert Mayr
Keyword(s):  
Rate Constants ◽  
Correlation Equation ◽  
Stopped Flow ◽  
Quinone Methides ◽  
Enol Ethers ◽  
Reactivity Descriptors ◽  
Silyl Enol Ethers ◽  
Nucleophilic Reactivity ◽  
Kinetics Of ◽  
Least Squares Minimization

The kinetics of the reactions of trimethylsilyl enol ethers and enamines (derived from deoxybenzoin, indane-1-one, and α-tetralone) with reference electrophiles (p-quinone methides, benzhydrylium and indolylbenzylium ions) were measured by conventional and stopped-flow photometry in acetonitrile at 20 °C. The resulting second-order rate constants were subjected to a least-squares minimization based on the correlation equation lg k = s N(N + E) for determining the reactivity descriptors N and s N of the silyl enol ethers and enamines. The relative reactivities of structurally analogous silyl enol ethers, enamines, and enolate anions towards carbon-centered electrophiles are determined as 1, 107, and 1014, respectively. A survey of synthetic applications of enolate ions and their synthetic equivalents shows that their behavior can be properly described by their nucleophilicity parameters, which therefore can be used for designing novel synthetic transformations.

scholarly journals Kinetic Analysis of the Effect of Poliovirus Receptor on Viral Uncoating: the Receptor as a Catalyst

2001 ◽  
Vol 75 (11) ◽  
pp. 4984-4989 ◽  
Author(s):  
Simon K. Tsang ◽  
Brian M. McDermott ◽  
Vincent R. Racaniello ◽  
James M. Hogle
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Kinetic Analysis ◽  
Transition State Theory ◽  
State Theory ◽  
Viral Receptor ◽  
Poliovirus Receptor ◽  
Entropic Stabilization ◽  
Entropic Effects

ABSTRACT We examined the role of soluble poliovirus receptor on the transition of native poliovirus (160S or N particle) to an infectious intermediate (135S or A particle). The viral receptor behaves as a classic transition state theory catalyst, facilitating the N-to-A conversion by lowering the activation energy for the process by 50 kcal/mol. In contrast to earlier studies which demonstrated that capsid-binding drugs inhibit thermally mediated N-to-A conversion through entropic stabilization alone, capsid-binding drugs are shown to inhibit receptor-mediated N-to-A conversion through a combination of enthalpic and entropic effects.

scholarly journals The Kinetics of Peroxynitrite on Insulin Nitration Damage

2020 ◽  
Author(s):  
Congxiao Zhang ◽  
Fusheng Sun ◽  
Congjiang Zhang ◽  
Yunjing Luo
Keyword(s):  
Activation Energy ◽  
Biological Activity ◽  
Glucose Metabolism ◽  
Rate Constants ◽  
The Body ◽  
Stopped Flow ◽  
Tyrosine Nitration ◽  
Protein Nitration ◽  
Physiological Conditions ◽  
Kinetics Of

Abstract Background: Insulin is one of the most important versatile hormones that is central to regulating the energy and glucose metabolism in the body. There has been accumulating evidence supporting that diabetes was associated with peroxynitrite and protein nitration, and insulin nitration induced by peroxynitrite affected its biological activity. Methods: In this paper, the kinetics of insulin nitration by peroxynitrite in physiological conditions was studied by the stopped flow technique. Results: We determined the values of the reactive rate constants of peroxynitrite decomposition and peroxynitrite-induced tyrosine nitration in the presence of insulin. The activation energy of peroxynitrite decomposition and 3-nitrotyrosine yield in the presence of insulin is 48.8 kJ·mol−1 and 42.7 kJ·mol−1 respectively. Conclusions: It is inferred that the glutamate residue of insulin accelerated peroxynitrite decomposition and tyrosine nitration by reducing the activation energy of reactions. The results could be beneficial for exploring the molecular mechanism of diabetes and offering a new target for diabetes therapies.

Sign in / Sign up

Export Citation Format

Share Document