The pressure dependence of benzyl chloride solvolysis in aqueous acetone and aqueous dimethylsulfoxide

1970 ◽  
Vol 48 (16) ◽  
pp. 2494-2499 ◽  
Author(s):  
Digby D. Macdonald ◽  
J. B. Hyne
Keyword(s):  
Transition State ◽  
Benzyl Chloride ◽  
Activation Volume ◽  
Aqueous Acetone ◽  
Solvent Composition ◽  
Pressure Data ◽  
Initial State ◽  
First Order ◽  
Solvent Systems ◽  
Aqueous Dimethylsulfoxide

First-order rate constants for the solvolysis of benzyl chloride in a series of aqueous acetone and aqueous dimethylsulfoxide (DMSO) mixtures at 50.100 °C and at various pressures in the range 1–4083 atm are reported. Volume of activation, calculated from the rate/pressure data, is found to exhibit extremum behavior with varying solvent composition in both solvent systems. The activation volumes are dissected into their initial state and transition state contributions by determining the "instantaneous" volumes of solution of benzyl chloride in the solvent systems. The contributions of both the initial state and the transition state to the behavior of the activation volume as a function of solvent composition are discussed.

Transition state volumes and solvolysis mechanisms

1970 ◽  
Vol 48 (13) ◽  
pp. 2025-2030 ◽  
Author(s):  
MOYRA J. Mackinnon ◽  
A. B. Lateef ◽  
J. B. Hyne
Keyword(s):  
Transition State ◽  
Benzyl Chloride ◽  
Activation Volume ◽  
Solvent Composition ◽  
Binary Solvent ◽  
Partial Molal Volume ◽  
Butyl Chloride ◽  
Molal Volume ◽  
Reaction Type

The transition state partial molal volume behavior, [Formula: see text] as a function of binary solvent composition was obtained for three reactions by dissection of the activation volume, ΔV*, into initial and transition state components: [Formula: see text] The solvolyses of t-butyl chloride, benzyl chloride, and p-chlorobenzyl chloride represented a gradation of reaction type between SN1 and SN2 and the transition state partial molal volume behavior was found to be distinctly different in each case and in agreement with the mechanistic classification of these reactions.

Solvolysis of isopropyl bromide in ethanol–water mixtures. Dissection into initial state and transition state contributions

1976 ◽  
Vol 54 (24) ◽  
pp. 3944-3948 ◽  
Author(s):  
Wiendelt Drenth ◽  
Michael Cocivera
Keyword(s):  
Vapor Pressure ◽  
Transition State ◽  
Thermodynamic Parameters ◽  
Activation Parameters ◽  
Solvent Composition ◽  
Initial State ◽  
Partial Vapor Pressure ◽  
State Variation

Rates were determined for the solvolysis of isopropyl bromide in ethanol–water mixtures (20 to 80% by volume of ethanol) at 50 and 75 °C and the corresponding activation parameters calculated. From the partial vapor pressure of isopropyl bromide over the various solutions at 50 and 75 °C, the variations in its initial state thermodynamic parameters were calculated. Thus, the variation in the activation parameters with solvent composition could be analyzed in terms of initial and transition state contributions. The initial state variation dominates according to a unimolecular as well as to a bimolecular treatment of data.

Partial molal volume behavior of tetraalkylammonium chlorides in aqueous acetone and aqueous dimethylsulfoxide

1970 ◽  
Vol 48 (15) ◽  
pp. 2416-2422 ◽  
Author(s):  
Digby D. Macdonald ◽  
J. B. Hyne
Keyword(s):  
Molecular Weight ◽  
Aqueous Acetone ◽  
Solvent Composition ◽  
Partial Molal Volume ◽  
Volume Data ◽  
Molal Volume ◽  
Partial Molal Volumes ◽  
Molal Volumes ◽  
Aqueous Dimethylsulfoxide ◽  
Linear Expression

The partial molal volumes of a series of tetraalkylammonium chlorides in aqueous acetone and aqueous dimethylsulfoxide at 25.000 °C are reported as a function of solvent composition. It is shown that for each solvent composition the partial molal volume data are better represented by a quadratic in solute molecular weight than by the linear expression previously employed in similar studies. Extrapolation of molecular partial molal volumes to zero cation molecular weight has permitted evaluation of the partial molal volumes of the ions R4N+ and Cl−. The variation of molecular and ionic partial molal volume as a function of solvent composition is discussed.

Solvolysis of Sulphonyl Halides. III. The Hydrolysis of Methane- and Ethanesulphonyl Chlorides in Aqueous Dioxan and Aqueous Acetone

1962 ◽  
Vol 15 (4) ◽  
pp. 668 ◽  
Author(s):  
R Foon ◽  
AN Hambly
Keyword(s):  
Low Temperature ◽  
Strong Evidence ◽  
Rate Constants ◽  
Pure Water ◽  
Aqueous Acetone ◽  
Solvent Composition ◽  
First Order ◽  
Extended Range ◽  
Transition Complex ◽  
Hydrolysis Of

The hydrolyses of methane- and ethanesulphonyl chlorides in aqueous acetone and aqueous dioxan, in the range 0.2-1.0 mole fraction of water, follow an SN2 mechanism. The first-order rate constants at low temperature go through a maximum as the composition of the solvent approaches pure water and there is a marked retardation at other temperatures. There is strong evidence that the nature of the transition complex is changing as the solvent composition is changed. The data arising from the use of an extended range of solvent composition have invalidated earlier discussions of the nature of this reaction.

Enthalpy and entropy of activation for benzyl chloride solvolysis in various alcohol–water solvent mixtures

1968 ◽  
Vol 46 (2) ◽  
pp. 125-129 ◽  
Author(s):  
H. S. Golinkin ◽  
J. B. Hyne
Keyword(s):  
Rate Constants ◽  
Benzyl Chloride ◽  
Solvent Composition ◽  
Solvent Mixtures ◽  
Methyl Ethyl ◽  
First Order ◽  
Water Solvent ◽  
Alcohol Water ◽  
Entropy Of Activation ◽  
Enthalpy And Entropy

The first order rate constants for the solvolysis of benzyl chloride in a series of mixtures of methyl, ethyl, i-propyl, and t-butyl alcohols with water are reported at 40.05 and 60.50 °C. The ΔH* and ΔS* values are calculated using these rate constants and those previously reported at 50.25 °C (1, 2). The dependence of these parameters on solvent composition is discussed.

Kinetic solvent effects on acid-catalyzed hydrolysis of sucrose in aqueous mixtures of some protic, aprotic, and dipolar aprotic solvents

1986 ◽  
Vol 64 (8) ◽  
pp. 1638-1642 ◽  
Author(s):  
Urmila Mandal ◽  
Kaushik Das ◽  
Kiron Kumar Kundu
Keyword(s):  
Transition State ◽  
Optical Rotation ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Initial State ◽  
Composition Profiles ◽  
Acid Catalyzed ◽  
Solvent Systems ◽  
Hydrolysis Of ◽  
Reference Electrolyte

Rate constants of acid-catalyzed hydrolysis of sucrose (S) to D-glucose and L-fructose have been determined at 25 °C by optical rotation measurements in aqueous mixtures of protophobic protic glycerol (GL), protophilic protic urea (UH), aprotic dioxane (D), and dipolar aprotic dimethyl sulphoxide (DMSO). Transfer free energies of the substrate sucrose, [Formula: see text] have also been determined in the solvents from solubility measurements. These values as well as those of H+, as obtained earlier by use of the widely used tetraphenylarsonium tetraphenylboron (TATB) reference electrolyte assumption, yielded transfer free energies of the transition state. The observed log (ks/kw) – composition profiles reveal that the rates increase monotonically in GL–water mixtures, that decrease more or less monotonically in UH– and DMSO–water mixtures, and decrease up to 10 mol% D in D–water mixtures, beyond which the values tend to increase. Examination of [Formula: see text]–composition profiles for the different species in each case indicates that the initial and transition state solvation get more or less compensated and the observed rates are dictated by the increased solvation of H+ in aqueous UH, DMSO, and D co-solvent systems. But in GL–water mixtures the decreased solvation of the transition state compared with the initial state is overcome by the decreased solvation of H+, thus resulting in the gradual enhancement of the rates of the reaction. The observed linearity of the correlative plots of −δ(ΔG≠) [= RT ln (ks/kw)] vs. [Formula: see text] with distinctly different slopes in the two cases also substantiates the relative importance of H+ solvation in dictating the rates of the reaction in these widely different aqueous co-solvents.

Kinetic solvent effects on alkaline decolorization of crystal violet in some aquo-organic solvents

1986 ◽  
Vol 64 (2) ◽  
pp. 300-307 ◽  
Author(s):  
Urmila Mandal ◽  
Sumita Sen ◽  
Kaushik Das ◽  
Kiron Kumar Kundu
Keyword(s):  
Transition State ◽  
Crystal Violet ◽  
Chemical Properties ◽  
Outer Sphere ◽  
Chloride Salt ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Initial State ◽  
Composition Profiles ◽  
Solvent Systems

Rate constants (ks) of alkaline fading of crystal violet (CV+) have been determined at 25 °C by spectrophotometric measurements in aqueous mixtures of some protic, aprotic, and dipolar aprotic cosolvents. Transfer free energies of the substrate (CV+), [Formula: see text], were also determined in some of the solvent systems from solubility measurements of the chloride salt, and by subtracting [Formula: see text] obtained earlier by use of the tetraphenylarsonium tetraphenylboron (TATB) extrathermodynamic assumption. This helped determine transfer free energies of the transition state (X≠), [Formula: see text] values of lyate ion (S−) based on the TATB assumption are already known for all of these solvent systems. The observed log (ks/kw) – composition profiles reveal that the relative solvation of the reacting species rather than the dielectric constant of the solvents dictates the complex variation of the rates of the reaction in these solvent systems. Correlation of [Formula: see text] with [Formula: see text] indicates that the reaction is largely controlled by the relative solvation of S− in most of the cases. But analysis of [Formula: see text] – composition profiles for some of the solvent systems reveals that the non-compensation of the [Formula: see text] contributions of initial-state substrate and of the transition-state complex, which may be considered to be an outer-sphere complex [CV+](S−), is also in accord with what is expected from the relative solvating characteristics of the cosolvents as guided by their respective physico-chemical properties.

Solvent effect on the initial state and transition state of anation of pentaammine-aquachromium(III) ion by thiocyanate

1993 ◽  
Vol 18 (1) ◽  
pp. 110-112 ◽  
Author(s):  
Olga A. ◽  
J�n Benko ◽  
Ol'ga Voll�rov� ◽  
Vladislav Holba
Keyword(s):  
Transition State ◽  
Solvent Effect ◽  
Initial State
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