ON THE PRESSURE DEPENDENCE OF REACTION RATES

1966 ◽  
Vol 44 (18) ◽  
pp. 2193-2203 ◽  
Author(s):  
H. S. Golinkin ◽  
W. G. Laidlaw ◽  
J. B. Hyne
Keyword(s):  
Pressure Dependence ◽  
Benzyl Chloride ◽  
Activation Volume ◽  
Functional Dependence ◽  
Quadratic Function ◽  
Activation Parameters ◽  
Reaction Rates ◽  
General Applicability ◽  
Order Polynomial ◽  
Derivatives Of

The functional dependence of the rate constant for benzyl chloride solvolysis on pressure is investigated with a view to obtaining reliable values of the activation parameters. It is concluded that a second order polynomial is the best description of this system, reproducing the experimental data with a greater degree of precision than the other published functions. A method for determining the precision of the derivatives of the logarithmic rate is presented, and the pressure dependence of the activation volume is demonstrated. Various systems from the literature are analyzed to demonstrate the general applicability of the quadratic function.

Effect of pressure on the rates of hydrolysis of allyl chlorides

1969 ◽  
Vol 47 (8) ◽  
pp. 1369-1373 ◽  
Author(s):  
A. B. Lateef ◽  
J. B. Hyne
Keyword(s):  
Temperature Dependence ◽  
Pressure Dependence ◽  
Activation Volume ◽  
Allyl Chloride ◽  
Activation Parameters ◽  
The Other ◽  
Effect Of Pressure ◽  
Hydrolysis Of

The pressure dependence of the rates of hydrolysis of allyl chloride and α-, β-, and γ-methyl allyl chlorides has been examined. The significance of the activation volumes, ΔV*, and their pressure dependence, dΔV*/dP, is discussed. These activation parameters indicate an SN2 mechanism for allyl and β-methyl allyl chloride and an SN1 or intermediate character mechanism for the other methyl substituted allyl chlorides investigated. The results are compared with the corresponding ΔH* and ΔCP* measurements of Robertson and co-workers. The temperature dependence of the activation volume, dΔV*/dT, for the solvolysis of the parent allyl chloride has been measured and found to be small and negative.

Quasilinearization Methods for Nonlinear Parabolic Equations with Functional Dependence

2002 ◽  
Vol 9 (3) ◽  
pp. 431-448
Author(s):  
A. Bychowska
Keyword(s):  
Cauchy Problem ◽  
Parabolic Equations ◽  
Unknown Function ◽  
Functional Dependence ◽  
Nonlinear Parabolic Equations ◽  
Quasilinearization Method ◽  
Convergence Theorems ◽  
Nonlinear Parabolic ◽  
Quasilinearization Methods ◽  
Derivatives Of

Abstract We consider a Cauchy problem for nonlinear parabolic equations with functional dependence. We prove convergence theorems for a general quasilinearization method in two cases: (i) the Hale functional acting only on the unknown function, (ii) including partial derivatives of the unknown function.

scholarly journals Perborate Oxidation of Substituted 5-Oxoacids in Aqueous Acetic Acid Medium: A Kinetic and Mechanistic Study

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Shree Devi ◽  
B. Muthukumaran ◽  
P. Krishnamoorthy
Keyword(s):  
Acetic Acid ◽  
Acid Medium ◽  
Reaction Rate ◽  
Reaction Medium ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Mechanistic Study ◽  
Aqueous Acetic Acid ◽  
Sodium Perborate ◽  
Acetic Acid Medium

Kinetics and mechanism of oxidation of substituted 5-oxoacids by sodium perborate in aqueous acetic acid medium have been studied. The reaction exhibits first order both in [perborate] and [5-oxoacid] and second order in [H+]. Variation in ionic strength has no effect on the reaction rate, while the reaction rates are enhanced on lowering the dielectric constant of the reaction medium. Electron releasing substituents in the aromatic ring accelerate the reaction rate and electron withdrawing substituents retard the reaction. The order of reactivity among the studied 5-oxoacids is p-methoxy ≫ p-methyl > p-phenyl > –H > p-chloro > p-bromo > m-nitro. The oxidation is faster than H2O2 oxidation. The formation of H2BO3+ is the reactive species of perborate in the acid medium. Activation parameters have been evaluated using Arrhenius and Eyring’s plots. A mechanism consistent with the observed kinetic data has been proposed and discussed. Based on the mechanism a suitable rate law is derived.

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.

Reactions of benzyl methyl substituted-benzyl phosphites with tert-butyl hypochlorite: "balanced TS" validating reactivity/selectivity principle

1998 ◽  
Vol 76 (6) ◽  
pp. 836-842
Author(s):  
Sung Soo Kim ◽  
Yu Zhu ◽  
In Seok Oh ◽  
Chang Gyeong Lim
Keyword(s):  
Benzyl Chloride ◽  
Activation Parameters ◽  
Differential Activation ◽  
Tert Butyl ◽  
Benzyl Chlorides ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Polar Transition ◽  
Isokinetic Relations ◽  
Selectivity Principle

Reactions of a series of several benzyl methyl substituted-benzyl phosphites with tert-butyl hypochlorite were investigated. The reactions produced phosphates, isobutene, alkyl chlorides, and benzyl chlorides via phosphonium chlorides as intermediates. Furthermore, the phosphates bearing a tert-butyl group underwent fragmentation to yield isobutene and another phosphates. Relative rates of formations of substituted benzyl and benzyl chloride (kY/kH) were measured at the temperatures (-20, 0, 20, 40°C). Logarithms of the rates (log kY/kH) were plotted against sigma + and 1/T, respectively. The former gave Hammett correlations to suggest a polar transition state (TS). The latter yielded differential activation parameters (ΔΔ Hdouble daggerY-H and ΔΔ Sdouble daggerY-H ), which indicate isokinetic relations and enthalpy control of rates. The selectivities (kY/kH) decrease with higher temperatures and thereby follow the reactivity/selectivity principle.Key words: phosphites, tert-butyl hypochlorite, Hammett correlations, differential activation terms, reactivity/selectivity principle.

A KINETICS AND MECHANISTIC STUDY OF THE OXIDATION OF L-ARGININE BY QDC IN DMF-WATER MEDIUM

2021 ◽  
pp. 11-12
Author(s):  
Deepika Jain ◽  
Shilpa Rathor
Keyword(s):  
Perchloric Acid ◽  
Reaction Rate ◽  
Main Product ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Mechanistic Study ◽  
Water Medium ◽  
Volume Percentage ◽  
Kinetics Of Oxidation ◽  
Kinetics Of

The present paper describes the kinetics of oxidation of l-Arginine by QDC in the presence of perchloric acid in 30% DMF-H O(v/v) medium at 2 + 40⁰C spectrophotometrically at λ =354nm. The reaction is rst order with respect to [QDC], [H ], and [substrate]. The reaction rate increased with max increasing volume percentage of DMF in reaction mixture. Michaelis- Menten type kinetic was observed with l-Arginine. The reaction rates were studied at different temperature and the activation parameters has been computed. The main product was identied as Cr (III) and 4-Guanidino buteraldehyde.

Kinetics of the Thermal Decomposition of Substituted Cyclic Organic Peroxides in Toluene Solution: Substituent Effects on the Reaction Rates and the Activation Parameters of the Unimolecular Reactions

Heterocycles ◽  
2004 ◽  
Vol 63 (10) ◽  
pp. 2231 ◽  
Author(s):  
Adriana I. Cañizo ◽  
Gladys N. Eyler ◽  
Carmen M. Mateo ◽  
Elida E. Alvarez ◽  
Rosa K. Nesprías
Keyword(s):  
Thermal Decomposition ◽  
Substituent Effects ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Toluene Solution ◽  
Organic Peroxides ◽  
Unimolecular Reactions ◽  
Kinetics Of

Temperature, Dynamics, and Enzyme-Catalyzed Reaction Rates

2020 ◽  
Vol 49 (1) ◽  
pp. 163-180 ◽  
Author(s):  
Vickery L. Arcus ◽  
Adrian J. Mulholland
Keyword(s):  
Molecular Mechanisms ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Rate Theory ◽  
Different Temperatures ◽  
State Ensemble ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions ◽  
Transition State Ensemble ◽  
Rate Limiting

We review the adaptations of enzyme activity to different temperatures. Psychrophilic (cold-adapted) enzymes show significantly different activation parameters (lower activation enthalpies and entropies) from their mesophilic counterparts. Furthermore, there is increasing evidence that the temperature dependence of many enzyme-catalyzed reactions is more complex than is widely believed. Many enzymes show curvature in plots of activity versus temperature that is not accounted for by denaturation or unfolding. This is explained by macromolecular rate theory: A negative activation heat capacity for the rate-limiting chemical step leads directly to predictions of temperature optima; both entropy and enthalpy are temperature dependent. Fluctuations in the transition state ensemble are reduced compared to the ground state. We show how investigations combining experiment with molecular simulation are revealing fundamental details of enzyme thermoadaptation that are relevant for understanding aspects of enzyme evolution. Simulations can calculate relevant thermodynamic properties (such as activation enthalpies, entropies, and heat capacities) and reveal the molecular mechanisms underlying experimentally observed behavior.

scholarly journals Kinetics of saccharose fermentation by Kombucha

2014 ◽  
Vol 20 (3) ◽  
pp. 345-352 ◽  
Author(s):  
Eva Loncar ◽  
Katarina Kanuric ◽  
Radomir Malbasa ◽  
Mirjana Djuric ◽  
Spasenija Milanovic
Keyword(s):  
Empirical Model ◽  
Black Tea ◽  
Reaction Rates ◽  
Yeast Cells ◽  
Inoculum Concentration ◽  
Viable Cells ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Very High

Kinetics of saccharose fermentation by Kombucha is not yet well defined due to lack of knowledge of reaction mechanisms taking place during this process. In this research kinetics of saccharose fermentation by Kombucha was analysed using the suggested empirical model. The data were obtained on 1.5 g L-1 of black tea, with 66.47 g L-1 of saccharose and using 10% (v/v) or 15% (v/v) of Kombucha. Total number of viable cells was as follows: approximately 5x105 of yeast cells per mL of the inoculum and approximately 2x106 of bacteria cells per mL of the inoculum. The samples were analysed after 0, 3, 4, 5, 6, 7 and 10 days. Their pH values and contents of saccharose, glucose, fructose, total acids and ethanol were determined. A saccharose concentration model was defined as sigmoidal function at 22oC and 30oC, and with 10% (v/v) and 15% (v/v) of inoculum quantity. Determination coefficients of the functions were very high (R2>0.99). Reaction rates were calculated as first derivatives of Boltzmann?s functions. No simple correlation between rate of reaction and independent variables (temperature and inoculum concentration) was found. Analysis of empirical model indicated that saccharose fermentation by Kombucha occurred according to very complex kinetics.

Benzyl Chloride Electroreduction on Ag Cathodes in CH3CN in the Presence of Small Amounts of Water: Evidences of Quantitative Effects on Reaction Rates and Mechanism

2013 ◽  
Vol 4 (4) ◽  
pp. 353-357 ◽  
Author(s):  
Ottavio Lugaresi ◽  
Alessandro Minguzzi ◽  
Cristina Locatelli ◽  
Alberto Vertova ◽  
Sandra Rondinini ◽  
...  
Keyword(s):  
Benzyl Chloride ◽  
Reaction Rates
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