scholarly journals Reaction Mechanisms and Rate Constants of Auto‐Catalytic Urethane Formation and Cleavage Reactions

ChemistryOpen ◽  
2021 ◽  
Author(s):  
Christoph Gertig ◽  
Eric Erdkamp ◽  
Andreas Ernst ◽  
Carl Hemprich ◽  
Leif C. Kröger ◽  
...  
Keyword(s):  
Rate Constants ◽  
Reaction Mechanisms ◽  
Urethane Formation ◽  
Cleavage Reactions

scholarly journals Theoretical investigation of the reaction mechanisms and kinetics of CFCl2CH2O2 and ClO in the atmosphere

RSC Advances ◽  
2020 ◽  
Vol 10 (44) ◽  
pp. 26433-26442
Author(s):  
Yunju Zhang ◽  
Bing He
Keyword(s):  
Theoretical Investigation ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Basis Sets ◽  
Thermal Rate Constants ◽  
Product Distributions ◽  
Kinetics Of

The reaction between CFCl2CH2O2 radicals and ClO was studied using the B3LYP and CCSD(T) methods associated with the 6-311++G(d,p) and cc-pVTZ basis sets, and subsequently RRKM-TST theory was used to predict the thermal rate constants and product distributions.

THE REACTION OF 2,2-DIPHENYL-1-PICRYLHYDRAZYL WITH SECONDARY AMINES

1958 ◽  
Vol 36 (12) ◽  
pp. 1729-1734 ◽  
Author(s):  
J. E. Hazell ◽  
K. E. Russell
Keyword(s):  
Secondary Amine ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Major Product ◽  
The Other ◽  
Secondary Amines ◽  
First Order ◽  
Kinetics Of

The reaction of DPPH (2,2-diphenyl-1-picrylhydrazyl) with N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, diphenylamine, and methylaniline has been studied and has been shown to be primarily a hydrogen abstraction process. Two moles DPPH react with 1–1.15 moles secondary amine to give 1.7–1.8 moles 2,2-diphenyl-1-picrylhydrazine and further products.The reaction between DPPH and N-phenyl-1-naphthylamine is first order with respect to each reactant. The reaction of DPPH with the other amines is retarded by the major product 2,2-diphenyl-1-picrylhydrazine and the kinetics of the over-all reaction are complex. However second-order rate constants and activation energies have been obtained using initial rates of reaction. Possible reaction mechanisms are discussed.

scholarly journals Temperature response of Rubisco kinetics in Arabidopsis thaliana: thermal breakpoints and implications for reaction mechanisms

2018 ◽  
Author(s):  
Ryan A. Boyd ◽  
Amanda P. Cavanagh ◽  
David S. Kubien ◽  
Asaph B. Cousins
Keyword(s):  
Arabidopsis Thaliana ◽  
Reaction Mechanism ◽  
Kinetic Parameters ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Temperature Response ◽  
Concentration Changes ◽  
The Individual ◽  
Temperature Responses ◽  
Individual Rate

ABSTRACTOptimization of Rubisco kinetics could improve photosynthetic efficiency, ultimatly resulting in increased crop yield. However, imprecise knowledge of the reaction mechanism and the individual rate constants limit our ability to optimize the enzyme. Membrane inlet mass spectrometery (MIMS) may offer benefits over traditional methods for determining individual rate constants of the Rubisco reaction mechanism, as it can directly monitor concentration changes in CO2, O2, and their isotopologs during assays. However, a direct comparsion of MIMS to the traditional Radiolabel method of determining Rubisco kinetic parameters has not been made. Here, the temperature responses of Rubisco kinetic parameters from Arabidopsis thaliana were measured using the Radiolabel and MIMS methods. The two methods provided comparable parameters above 25 °C, but temperature responses deviated at low temperature as MIMS derived catalytic rates of carboxylation, oxygenation, and CO2/O2 specificity showed thermal breakpoints. Here we discuss the variability and uncertainty surrounding breakpoints in the Rubisco temperature response and relavance of individual rate constants of the reaction mechanisms to potential breakpoints.

Computational study on the mechanisms and kinetics of the CH2CCl + O2 reaction

2020 ◽  
Vol 98 (8) ◽  
pp. 395-402
Author(s):  
Yunju Zhang ◽  
Bing He ◽  
Yuxi Sun
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Pressure Dependence ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Energy Surface ◽  
Computational Study ◽  
Tddft Calculations ◽  
Temperature And Pressure ◽  
Kinetics Of

The potential energy surface for the CH2CCl + O2 reaction has been investigated by using the CCSD(T)/cc-pVTZ//B3LYP/6-311++G(d,p) method. Two type reaction mechanisms have been located. The H-abstraction of CH2CCl by O2 generates CHCCl + HO2 surmounting a 20.86 kcal/mol barrier. The addition between O2 and CH2CCl proceeds to an intermediate CH2CClO2 (IM1t and IM1c) without a barrier, which can further dissociate or isomerize to various products with the complicated processes. The temperature and pressure dependence rate constants for the CH2CCl + O2 reaction were computed by means of multi-channel RRKM-TST theory. Moreover, TDDFT calculations imply that IM1t, IM1c, IM2, IM4, IM5t, and IM5c will photolyze under the sunlight.

Reactions of lumiflavin with amine radicals

1985 ◽  
Vol 63 (7) ◽  
pp. 1357-1364 ◽  
Author(s):  
Parminder S. Surdhar ◽  
Douglas E. Bader ◽  
David A. Armstrong
Keyword(s):  
Quantum Yield ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Primary Amine ◽  
Pulse Radiolysis ◽  
Ethylene Diamine ◽  
Secondary Amines ◽  
Diamine Tetraacetate ◽  
Effects Of Ph ◽  
Electron Reduction

The amino radicals (•AH) formed by the 60Co radiolysis of N2O-saturated 0,05 M solutions of ethylene diamine tetraacetate (EDTA) at pH 7 and 11.2 and of glycine at pH 11.2 brought about an efficient two-electron reduction of lumiflavin (Fl). The spectra of the products were identical to those formed by photolysis of the same solutions and by reduction of the lumiflavin with •CO2− radicals. The products were reoxidised to flavin by oxygen. The quantum yield for flavin disappearance was 0.52 ± 0.07 and 0.17 ± 0.01 in the presence of EDTA at pH 7 and 11.2 and 0.065 ± 0.008 and 0.17 ± 0.01 for glycine at the same pHs, respectively.The overall two-electron reduction can be explained by the mechanism:[Formula: see text]The rate constants of reaction [4] were found by pulse radiolysis to be 1.8 ± 0.3 × 109 and 1.5 ± 0.3 × 109 M−1s−1 for the radicals of glycine and EDTA at pH 7 and 3.6 ± 0.3 × 108 M s−1 for glycine radicals at pH 11.2. The spectrum of •FlH formed by glycine radicals at pH 7 is similar to that produced by•CO2−, but there was some perturbation, which is apparently due to interaction with the amine.The radicals formed from the secondary amines piperazine and diethylamine at pH 11.8 also effected reversible two-electron reduction. However, the radicals from glycine anhydride and the primary amine ethylamine yielded significant amounts of non-oxidisable products. The reaction mechanisms are discussed and effects of pH are considered.

THE KINETICS OF THE DECOMPOSITION AND SYNTHESIS OF SOME DITHIOCARBAMATES

1962 ◽  
Vol 40 (2) ◽  
pp. 246-255 ◽  
Author(s):  
D. M. Miller ◽  
R. A. Latimer
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Dissociation Constants ◽  
Activation Energies ◽  
Spectral Evidence ◽  
Kinetics Of

Rate constants, activation energies, and dissociation constants were determined in a kinetic study of the synthesis and decomposition of a number of N-substituted dithiocarbamates. These data combined with certain spectral evidence are evaluated and reaction mechanisms suggested.

scholarly journals Properties of methyl acetimidate and its use as a protein-modifying reagent

1981 ◽  
Vol 193 (1) ◽  
pp. 245-249 ◽  
Author(s):  
A J Makoff ◽  
A D B Malcolm
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Effect Of Ph ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The rate of hydrolysis of the imido ester methyl acetimidate and its rate of amidination of denatured aldolase were investigated under different conditions of temperature, pH and ionic strength. Both rate constants increase greatly with temperature, whereas ionic strength has no effect on either. The effect of pH is more complex. Between pH 6.8 and 8.8 the rate of hydrolysis decreases and the rate of amidination increases. These results are discussed in terms of the reaction mechanisms involved.

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