Kinetics and mechanism of nucleophilic displacements with heterocycles as leaving groups. Part 23. Studies at the borderlines between reactions proceeding (i) via free carbocations, (ii) via rate-determining formation of ion–molecule pairs, and (iii) via rate-determining nucleophilic attack on ion–molecule pairs

1986 ◽  
Vol 64 (6) ◽  
pp. 1161-1169 ◽  
Author(s):  
Alan R. Katritzky ◽  
Bogumil Brycki
Keyword(s):  
Order Reaction ◽  
Second Order ◽  
Kinetics And Mechanism ◽  
First Order Reaction ◽  
Nucleophilic Attack ◽  
First Order ◽  
Order Rate ◽  
Leaving Groups ◽  
Nucleophilic Trapping

Evidence is presented to demonstrate that at the borderline between first-order reaction via nucleophilic trapping of intimate ion–molecule pairs and first-order reaction via the formation of free carbocations, both mechanisms proceed independently, without merging. Similarly at the borderline between first-order (rate-determining formation) and second-order (rate-determining nucleophilic attack) reactions of intimate ion–molecule pairs, both reactions again proceed independently.

scholarly journals Roles of solution concentration and shear rate in the shear-induced crystallization of P3HT

RSC Advances ◽  
2021 ◽  
Vol 11 (32) ◽  
pp. 19673-19681
Author(s):  
Jiaxin He ◽  
Ying Liu ◽  
Fengquan Liu ◽  
Jianjun Zhou ◽  
Hong Huo
Keyword(s):  
Shear Rate ◽  
Crystallization Kinetics ◽  
Solution Concentration ◽  
Order Reaction ◽  
Second Order ◽  
Crystallization Mechanism ◽  
First Order Reaction ◽  
First Order ◽  
Induced Crystallization

The shear temperature and solution concentration determine the FIP content. Increasing FIPs can accelerate the crystallization kinetics and change the crystallization mechanism from a second-order to a first-order reaction.

Kinetics and Mechanism of Hübnerite (MnWO4) and Ferberite (FeWO4)Crystallization under Hydrothermal Conditions

1984 ◽  
Vol 39 (10) ◽  
pp. 963-965 ◽  
Author(s):  
J. Chr. Buhl ◽  
A. Willgallis
Keyword(s):  
Rate Constants ◽  
Sodium Tungstate ◽  
Order Reaction ◽  
Kinetics And Mechanism ◽  
Mixed Crystals ◽  
First Order Reaction ◽  
Hydrothermal Conditions ◽  
First Order ◽  
Two Temperatures ◽  
Kinetics Of

Abstract The kinetics of the crystallization of hiibnerite (MnWO4) and ferberite (FeWO4) was studied by hydrothermally reacting the metal (II)-chlorides and sodium tungstate in a special autoclave at two temperatures (300 °C. 400 °C) and a pressure of 1 kbar. The rates of crystallization were determined by continual removal of the reactants from the autoclave. At both temperatures, the decrease of tungstate concentration in solution followed at first order reaction. The rate constants of the reactions were calculated and the Jerofejev-equation was used to describe the kinetics. The rate of hiibnerite formation was larger and increased faster with temperature. This should affect the formation of mixed crystals by initiating a shift of the composition towards higher MnWO4/FeWO4 ratios and might well account for a zonation or inhomogeneity of natural wolframites.

Rubber Chemicals from Cyclic Amines. V. Thiocarbamyl Sulfenamide Accelerators Derived from 3-Azabicyclo(3.2.2)Nonane

1971 ◽  
Vol 44 (4) ◽  
pp. 889-897 ◽  
Author(s):  
J. J. D'Amico ◽  
E. Morita
Keyword(s):  
Crosslink Density ◽  
Major Part ◽  
Order Reaction ◽  
Second Order ◽  
Crosslinking Reaction ◽  
Second Order Reaction ◽  
Amino Groups ◽  
First Order ◽  
Cyclic Amines ◽  
Order Rate

Abstract Evaluation of thiocarbamyl sulfenamides (I) prepared from 3-azabicyclo-(3.2.2) nonane and other amines indicates that the curing properties of stocks accelerated by (I) are influenced by the amino groups which constitute the thiocarbamyl and sulfenamide moieties, R and R′, respectively, and also vary with the formulation of the rubber stocks. The fastest cures are obtained when R is pyrrolidinyl or dimethyl and slowest cure when R′ is N-tert-butyl or N-morpholino. The lowest maximum crosslink density is obtained with morpholino- or piperidinothiocarbonyl sulfenamide. In a non-extended SBR black stock the crosslinking reaction generally proceeds as a second order reaction. The major part of the crosslinking reaction of the slower curing stocks proceeds by a fast first order rate followed by a slower first order rate.

Leaching Kinetics of Atrazine and Inorganic Chemicals in Tilled and Orchard Soils

2014 ◽  
Vol 28 (2) ◽  
pp. 231-237 ◽  
Author(s):  
Lech W. Szajdak ◽  
Jerzy Lipiec ◽  
Anna Siczek ◽  
Artur Nosalewicz ◽  
Urszula Majewska
Keyword(s):  
Reaction Rate ◽  
Inorganic Compounds ◽  
Model Performance ◽  
Order Reaction ◽  
First Order Reaction ◽  
Order Kinetic ◽  
Time Data ◽  
First Order ◽  
Concentration Changes ◽  
Reaction Constants

Abstract The aim of this study was to verify first-order kinetic reaction rate model performance in predicting of leaching of atrazine and inorganic compounds (K+1, Fe+3, Mg+2, Mn+2, NH4 +, NO3 - and PO4 -3) from tilled and orchard silty loam soils. This model provided an excellent fit to the experimental concentration changes of the compounds vs. time data during leaching. Calculated values of the first-order reaction rate constants for the changes of all chemicals were from 3.8 to 19.0 times higher in orchard than in tilled soil. Higher first-order reaction constants for orchard than tilled soil correspond with both higher total porosity and contribution of biological pores in the former. The first order reaction constants for the leaching of chemical compounds enables prediction of the actual compound concentration and the interactions between compound and soil as affected by management system. The study demonstrates the effectiveness of simultaneous chemical and physical analyses as a tool for the understanding of leaching in variously managed soils.

The Kinetics of Glucose Decomposition with Sulfate Reduction in the Anaerobic Fluidized Bed Reactor

1993 ◽  
Vol 28 (2) ◽  
pp. 135-144 ◽  
Author(s):  
S. Matsui ◽  
R. Ikemoto Yamamoto ◽  
Y. Tsuchiya ◽  
B. Inanc
Keyword(s):  
Sulfate Reduction ◽  
Fluidized Bed ◽  
Kinetic Equations ◽  
Fluidized Bed Reactor ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Glucose Decomposition ◽  
Reaction Equations ◽  
Kinetics Of

Using a fluidized bed reactor, experiments on glucose decomposition with and without sulfate reduction were conducted. Glucose in the reactor was mainly decomposed into lactate and ethanol. Lactate was mainly decomposed into propionate and acetate, while ethanol was decomposed into propionate, acetate, and hydrogen. Sulfate reduction was not involved in the decomposition of glucose, lactate, and ethanol, but was related to propionate and acetate decomposition. The stepwise reactions were modeled using either a Monod expression or first order reaction kinetics in respect to the reactions. The coefficients of the kinetic equations were determined experimentally. The modified Monod and first order reaction equations were effective at predicting concentrations of glucose, lactate, ethanol, propionate, acetate, and sulfate along the beight of the reactor. With sulfate reduction, propionate was decomposed into acetate, while without sulfate reduction, accumulation of propionate was observed in the reactor. Sulfate reduction accelerated propionate conversion into acetate by decreasing the hydrogen concentration.

Complete monotonicity of entropy production in chemical reaction

1981 ◽  
Vol 46 (2) ◽  
pp. 452-456
Author(s):  
Milan Šolc
Keyword(s):  
Entropy Production ◽  
Equilibrium Constant ◽  
Chemical Reaction ◽  
Relative Entropy ◽  
Order Reaction ◽  
Complete Monotonicity ◽  
First Order Reaction ◽  
First Order ◽  
Completely Monotonic ◽  
Derivatives Of

The successive time derivatives of relative entropy and entropy production for a system with a reversible first-order reaction alternate in sign. It is proved that the relative entropy for reactions with an equilibrium constant smaller than or equal to one is completely monotonic in the whole definition interval, and for reactions with an equilibrium constant larger than one this function is completely monotonic at the beginning of the reaction and near to equilibrium.

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

scholarly journals Determination of exothermic batch reactor specific model parameters

2019 ◽  
Vol 292 ◽  
pp. 01063
Author(s):  
Lubomír Macků
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Specific Model ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
First Order Reaction ◽  
Model Parameters ◽  
Reactor Model ◽  
First Order

An alternative method of determining exothermic reactor model parameters which include first order reaction rate constant is described in this paper. The method is based on known in reactor temperature development and is suitable for processes with changing quality of input substances. This method allows us to evaluate the reaction substances composition change and is also capable of the reaction rate constant (parameters of the Arrhenius equation) determination. Method can be used in exothermic batch or semi- batch reactors running processes based on the first order reaction. An example of such process is given here and the problem is shown on its mathematical model with the help of simulations.

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