The Solvent Effects on Kinetics and Mechanism of Zinc or Cadmium Halide Catalyzed Reactions of Hydrosilanes with Hydroxylic Reagents

2004 ◽  
Vol 69 (12) ◽  
pp. 2281-2296 ◽  
Author(s):  
Jerzy J. Chruściel
Keyword(s):  
Dielectric Constant ◽  
Solvent Effects ◽  
Kinetic Method ◽  
Kinetic Studies ◽  
Reaction Rates ◽  
Nucleophilic Catalysis ◽  
Effect Of Solvent ◽  
Cadmium Bromide ◽  
Catalyzed Reactions

The effect of solvent composition on reaction rates was studied by a kinetic method for reactions of Et3SiH with Ph2Si(OH)2 in the presence of ZnCl2 in a mixture of DMF and THF or Et3SiH with PhCOOH and cadmium bromide CdBr2 in DMF-1,4-dioxane and DMF-THF. A decrease in reaction rates with decreasing polarity of the medium (and its dielectric constant) has been observed. The kinetic order of dehydrocoupling reaction with respect to DMF was determined from kinetic studies. The constants of nucleophilic catalysis with DMF (λ) were found. The role of DMF in the mechanism of dehydrocoupling of hydrosilanes with hydroxylic reagents in the presence of ZnX2 and CdX2 halides (X = Cl, Br, I) is discussed.

scholarly journals A kinetic method for the study of solvent environments of thiol groups in proteins involving the use of a pair of isomeric reactivity probes and a differential solvent effect. Investigation of the active centre of ficin by using 2,2'- and 4,4'- dipyridyl disulphides as reactivity probes

1980 ◽  
Vol 185 (1) ◽  
pp. 217-222 ◽  
Author(s):  
J P G Malthouse ◽  
K Brocklehurst
Keyword(s):  
Dielectric Constant ◽  
Physicochemical Properties ◽  
Solvent Effect ◽  
Rate Constants ◽  
Kinetic Method ◽  
Thiol Group ◽  
Analogous Reaction ◽  
Thiol Groups ◽  
Active Centre ◽  
Effect Of Solvent

1. Whereas the second-order rate constants for the reaction of the thiolate ion of 2-mercaptoethanol with 4,4'-dipyridyl disulphide (k4PDS) and with 5,5'-dithiobis-2-nitrobenzoate dianion increase with decreasing dielectric constant of the solvent, or remain unchanged, the rate constant for the analogous reaction with 2,2'-dipyridyl disulphide (k2PDS) decreases. This anomalous solvent effect and other unusual physicochemical properties of 2,2'-dipyridyl disulphide are discussed. 2. The differential effect of solvent on the reactions of thiolate ion with the 2,2'- and 4,4'-dipyridyl disulphides is shown to provide a method of characterizing solvent environments of thiol groups in proteins by a reactivity-probe method that should not suffer from the usual drawback associated with the existence of steric or binding effects of unknown magnitude. Application of the method to ficin (EC 3.4.22.3) suggests that its active-centre thiol group resides in a relatively hydrophobic environment. 3. The pH-k profile for the reaction of ficin with 4,4'-dipyridyl disulphide is reported.

scholarly journals Universal kinetic solvent effects in acid-catalyzed reactions of biomass-derived oxygenates

2018 ◽  
Vol 11 (3) ◽  
pp. 617-628 ◽  
Author(s):  
Theodore W. Walker ◽  
Alex K. Chew ◽  
Huixiang Li ◽  
Benginur Demir ◽  
Z. Conrad Zhang ◽  
...  
Keyword(s):  
Organic Solvent ◽  
Solvent Effects ◽  
Biomass Conversion ◽  
Molecular Simulations ◽  
Reaction Rates ◽  
Acid Catalyzed ◽  
Catalyzed Reactions

Experiments and molecular simulations are combined to understand organic solvent effects, enabling prediction of acid-catalyzed reaction rates for biomass conversion.

SULPHONIUM SALT SOLVOLYSIS: PART IV. SOLVENT EFFECTS

1963 ◽  
Vol 41 (7) ◽  
pp. 1679-1685 ◽  
Author(s):  
J. B. Hyne ◽  
J. H. Jensen
Keyword(s):  
Dielectric Constant ◽  
Ethylene Glycol ◽  
Binary Mixtures ◽  
Solvent Effects ◽  
Solvent Composition ◽  
Activation Process

The variation of rate of solvolysis of dimethyl-t-butyl sulphonium iodide as a function of solvent composition is reported for various binary mixtures of water with ethanol, N,N-dimethylformamide, N-methylformamide, dioxane, and ethylene glycol. The inadequacy of solvent bulk dielectric constant as a correlating parameter is demonstrated and solvent Y and Z parameters are compared in this respect. The importance of the specific microscopic role of the solvent in the activation process is demonstrated and a possible important nucleophilic role for the amides suggested. Deviations in dioxane and ethylene glycol systems are discussed.

Kinetic Solvent Effects in Organic Reactions

2017 ◽  
Author(s):  
Belinda Slakman ◽  
Richard West
Keyword(s):  
Solvent Effect ◽  
Reaction Kinetics ◽  
Computational Methods ◽  
High Throughput ◽  
Kinetic Modeling ◽  
Solvent Effects ◽  
Reaction Rates ◽  
Prior Work ◽  
Solvent Phase ◽  
High Throughput Manner

<div> <div> <div> <p>This article reviews prior work studying reaction kinetics in solution, with the goal of using this information to improve detailed kinetic modeling in the solvent phase. Both experimental and computational methods for calculating reaction rates in liquids are reviewed. Previous studies, which used such methods to determine solvent effects, are then analyzed based on reaction family. Many of these studies correlate kinetic solvent effect with one or more solvent parameters or properties of reacting species, but it is not always possible, and investigations are usually done on too few reactions and solvents to truly generalize. From these studies, we present suggestions on how best to use data to generalize solvent effects for many different reaction types in a high throughput manner. </p> </div> </div> </div>

Can the Lewis basicity of an isolated solvent molecule be used for characterizing solvent effects?

2020 ◽  
Vol 16 ◽  
Author(s):  
Jean-François Gal ◽  
Pierre-Charles Maria
Keyword(s):  
Solvent Effects ◽  
Molecular Level ◽  
Solvent Molecule ◽  
Lewis Base ◽  
Bulk Liquid ◽  
Donor Number ◽  
Special Focus ◽  
Solution Processes ◽  
Inert Solvent

Background: The ubiquitous Lewis acid/base interactions are important in solution processes. Analytical chemistry may benefit of a better understanding of the role of Lewis basicity, at the molecular level or acting through a bulk solvent effect. Objective: To clearly delineate (i) the basicity at a molecular level, hereafter referred as solute basicity, and (ii) the solvent basicity, which is a bulk-liquid property. Method: The literature that relates Lewis basicity scales and solvent effects is analyzed. A special focus is placed on two extensive scales, the Donor Number, DN, and the BF3 affinity scale, BF3A, which were obtained by calorimetric measurement on molecules as solutes diluted in a quasi-inert solvent, and therefore define a molecular Lewis basicity. We discuss the validity of these solute scales when regarded as solvent scales, in particular when the basicity of strongly associated liquids is discussed. Results: We demonstrate the drawbacks of confusing the Lewis basicity of a solvent molecule, isolated as solute, and that of the bulk liquid solvent itself. Conclusion: Consequently, we recommend a reasoned use of the concept of Lewis basicity taking clearly into account the specificity of the process for which a Lewis basicity effect may be invoked. In particular, the action of the Lewis base, either as an isolated entity, or as a bulk liquid, must be distinguished.

Role of Lys-226 in the Catalytic Mechanism ofBacillus StearothermophilusSerine HydroxymethyltransferaseCrystal Structure and Kinetic Studies†,‡

Biochemistry ◽  
2005 ◽  
Vol 44 (18) ◽  
pp. 6929-6937 ◽  
Author(s):  
Siddegowda Bhavani ◽  
V. Trivedi ◽  
V. R. Jala ◽  
H. S. Subramanya ◽  
Purnima Kaul ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Kinetic Studies

Probing the Role of Tyr 64 ofTreponema denticolaCystalysin by Site-Directed Mutagenesis and Kinetic Studies†

Biochemistry ◽  
2005 ◽  
Vol 44 (42) ◽  
pp. 13970-13980 ◽  
Author(s):  
Barbara Cellini ◽  
Mariarita Bertoldi ◽  
Riccardo Montioli ◽  
Carla Borri Voltattorni
Keyword(s):  
Kinetic Studies ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis

scholarly journals The comparative study of linear solvatation energy relationship for the reactivity of pyridine carboxylic acids with diazodiphenylmethane in protic and aprotic solvents

2012 ◽  
Vol 77 (10) ◽  
pp. 1311-1338 ◽  
Author(s):  
Sasa Drmanic ◽  
Jasmina Nikolic ◽  
Aleksandar Marinkovic ◽  
Bratislav Jovanovic
Keyword(s):  
Solvent Effects ◽  
Kinetic Data ◽  
Aprotic Solvent ◽  
Isonicotinic Acid ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Reaction Rates ◽  
Aprotic Solvents ◽  
Pyridine Carboxylic ◽  
The Comparative Study

Protic and aprotic solvent effects on the reactivity of picolinic, nicotinic and isonicotinic acid, as well as of some substituted nicotinic acids with diazodiphenylmethane (DDM) were investigated. In order to explain the kinetic results through solvent effects, the second-order rate constants for the reaction of the examined acids with DDM were correlated using the Kamlet-Taft solvatochromic equation. The correlations of the kinetic data were carried out by means of the multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and the transition state. The signs of the equation coefficients support the already known reaction mechanism. The solvatation models for all the investigated acids are suggested and related to their specific structure.

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