Solvent Effects in the Regio- and Diastereoselective Epoxidations of Acyclic Allylic Alcohols by Dimethyldioxirane:  Hydrogen Bonding as Evidence for a Dipolar Transition State

1996 ◽  
Vol 61 (10) ◽  
pp. 3506-3510 ◽  
Author(s):  
Waldemar Adam ◽  
Alexander K. Smerz
Keyword(s):  
Hydrogen Bonding ◽  
Transition State ◽  
Solvent Effects ◽  
Allylic Alcohols

A quantitative analysis of solvent effects on reaction constant

1980 ◽  
Vol 33 (6) ◽  
pp. 1175 ◽  
Author(s):  
B Poh
Keyword(s):  
Dielectric Constant ◽  
Hydrogen Bonding ◽  
Quantitative Analysis ◽  
Transition State ◽  
Organic Acids ◽  
Carboxylic Acids ◽  
Solvent Effects ◽  
Effective Dielectric Constant ◽  
Reaction Constant

Solvent effects on reaction constant ρ for the dissociation equilibria of several series of organic acids are analysed in terms of three factors, namely, (i) variation in the effective dielectric constant, (ii) variation in the hydrogen-bonding ability of solvents, and (iii) variation in the conformation of the acids. A fourth factor, variation in the charge developed in the transition state of the reaction, is included in the analysis of ρ for reactions between diazodiphenylmethane and several series of carboxylic acids. It is shown that the ρ values for the dissociation equilibria of series of acids in other solvents can be calculated from their ρ values in water.

THE INHIBITED AUTOXIDATION OF STYREN: PART IV. SOLVENT EFFECTS

1964 ◽  
Vol 42 (5) ◽  
pp. 1044-1056 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Hydrogen Bonding ◽  
Transition State ◽  
Solvent Effects ◽  
Dielectric Constants ◽  
Hydroxyl Group ◽  
Phenolic Antioxidants ◽  
Oxidation Reactions ◽  
Effect Of Solvents ◽  
Hydrogen Bonding Interactions ◽  
Influence Of Solvents

The influence of solvents on the rate of the uninhibited oxidation of styrene can be roughly correlated with the dielectric constants of the solvents. It is suggested that the propagation reaction involves a dipolar transition state and that the magnitude of the solvent effects might be used to identify dipolar transition states in other oxidation reactions. The effect of solvents on the rate of oxidation of styrene inhibited by phenolic antioxidants is attributed to hydrogen bonding interactions between the phenolic hydroxyl group and the solvent. The magnitude of these interactions depends on the acidity of the phenol and on the degree of steric protection afforded the hydroxyl group by ortho-alkyl substituents.

On the Calculation of Transition State Activity Coefficient and Solvent Effects on Chemical Reactions

1998 ◽  
Vol 63 (12) ◽  
pp. 1969-1976 ◽  
Author(s):  
Alvaro Domínguez ◽  
Rafael Jimenez ◽  
Pilar López-Cornejo ◽  
Pilar Pérez ◽  
Francisco Sánchez
Keyword(s):  
Activity Coefficient ◽  
Transition State ◽  
Chemical Reactions ◽  
Solvent Effects ◽  
Transition State Theory ◽  
Reaction Medium ◽  
State Theory ◽  
Precursor Complex ◽  
State Activity ◽  
Classical Transition

Solvent effects, when the classical transition state theory (TST) holds, can be interpreted following the Brønsted equation. However, when calculating the activity coefficient of the transition state, γ# it is important to take into account that this coefficient is different from that of the precursor complex, γPC. The activity coefficient of the latter is, in fact, that calculated in classical treatments of salt and solvent effects. In this paper it is shown how the quotients γ#/γPC change when the reaction medium changes. Therefore, the conclusions taken on the basis of classical treatments may be erroneous.

THE ALKALINE CLEAVAGE OF o-NITROBENZYLTRIMETHYLSILANE SOLVENT EFFECTS IN THE DIOXANE–WATER SYSTEM

1963 ◽  
Vol 41 (6) ◽  
pp. 1525-1530 ◽  
Author(s):  
H. R. Allcock
Keyword(s):  
Transition State ◽  
Solvent Effects ◽  
Water System ◽  
Solvent Polarity ◽  
High Water ◽  
Aqueous Dioxane ◽  
Alkaline Cleavage ◽  
Rate Of Reaction ◽  
Kinetics Of

The kinetics of alkaline cleavage of o-nitrobenzyltrimethylsilane were examined in aqueous dioxane media. At high water concentrations, increases in solvent polarity retard the cleavage, as required by a mechanism involving charge dispersion in the transition state. At high dioxane concentrations, solvent polarity increases are accompanied by increases in the rate of reaction, a result which may reflect association between the solvent components.

STRUCTURAL AND SOLVENT EFFECTS ON THE n → π*(′U ← ′A) TRANSITIONS IN ALIPHATIC CARBONYL DERIVATIVES: EVIDENCE FOR HYPERCONJUGATION IN THE ELECTRONICALLY EXCITED STATES OF MOLECULES

1960 ◽  
Vol 38 (12) ◽  
pp. 2508-2513 ◽  
Author(s):  
C. N. R. Rao ◽  
G. K. Goldman ◽  
A. Balasubramanian
Keyword(s):  
Hydrogen Bonding ◽  
Carbonyl Group ◽  
Excited States ◽  
Solvent Effects ◽  
Electronically Excited States ◽  
Carbonyl Derivatives ◽  
Alkyl Groups ◽  
Electronically Excited

The n → π* transition of the carbonyl group has been studied in solvents of varying degree of polarity and hydrogen-bonding ability, in a number of aliphatic carbonyl derivatives. Evidence for hyperconjugation of the alkyl groups in the electronically excited states of molecules has been presented.

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