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.

Chlorine isotope effects in the solvolysis of substituted 1-phenylethyl chlorides

1986 ◽  
Vol 64 (6) ◽  
pp. 1201-1205 ◽  
Author(s):  
Duncan J. McLennan ◽  
Allan R. Stein ◽  
Brian Dobson
Keyword(s):  
Transition State ◽  
Theoretical Calculations ◽  
Isotope Effects ◽  
Chloride Ion ◽  
Solvent Composition ◽  
Solvent Mixtures ◽  
Chlorine Isotope ◽  
Water Solvent ◽  
Alcohol Water ◽  
Substituted 1

Kinetic chlorine isotope effects attending the solvolysis of several ring-substituted 1-phenylethyl chlorides in alcohol–water solvent mixtures are reported. The k35/k37 values are insensitive to the identity of ring substituents and to solvent composition. Results are interpreted in terms of an SN1 heterolytic process incorporating a significant amount of internal return. Theoretical calculations suggest that the incipient chloride ion in the transition state may be strongly hydrogen-bonded.

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.

Solubility and Thermoresponsiveness of PMMA in Alcohol-Water Solvent Mixtures

2010 ◽  
Vol 63 (8) ◽  
pp. 1173 ◽  
Author(s):  
Richard Hoogenboom ◽  
C. Remzi Becer ◽  
Carlos Guerrero-Sanchez ◽  
Stephanie Hoeppener ◽  
Ulrich S. Schubert
Keyword(s):  
Methyl Methacrylate ◽  
Pure Water ◽  
Polymer Concentration ◽  
Polymer Processing ◽  
Solution Temperature ◽  
Solvent Mixtures ◽  
Poly Methyl Methacrylate ◽  
Water Solvent ◽  
Alcohol Water ◽  
Hysteresis Behaviour

To reduce the environmental burden of polymer processing, the use of non-toxic solvents is desirable. In this regard, the improved solubility of poly(methyl methacrylate) (PMMA) in ethanol/water solvent mixtures is very appealing. In this contribution, detailed investigations on the solubility of PMMA in alcohol/water solvent mixtures are reported based on turbidimetry measurements. PMMA revealed upper critical solution temperature transitions in pure ethanol and ethanol/water mixtures. However, around 80 wt-% ethanol content a solubility maximum was observed for PMMA as indicated by a decrease in the transition temperature. Moreover, the transition temperatures increased with increasing PMMA molar mass as well as increasing polymer concentration. Careful analysis of both heating and cooling turbidity curves revealed a peculiar hysteresis behaviour with a higher precipitation temperature compared with dissolution with less than 60 wt-% or more than 90 wt-% ethanol in water and a reverse hysteresis behaviour at intermediate ethanol fractions. Finally, the transfer of poly(styrene)-block-poly(methyl methacrylate) block copolymer micelles from the optimal solvent, i.e. aqueous 80 wt-% ethanol, to almost pure water and ethanol is demonstrated.

Effect of pressure on the solvolysis of benzyl chloride in glycerol–water mixtures

1970 ◽  
Vol 48 (13) ◽  
pp. 2021-2024 ◽  
Author(s):  
D. L. Gay ◽  
E. Whalley
Keyword(s):  
Benzyl Chloride ◽  
Constant Pressure ◽  
Solvent Composition ◽  
Constant Volume ◽  
Glycerol Water ◽  
Effect Of Pressure ◽  
Solvent Dependence ◽  
Partial Volumes ◽  
Volume Energy ◽  
Entropy Of Activation

The effect of pressure up to 1.6 kbar on the rate of solvolysis of benzyl chloride in 0 to 75% v/v glycerol–water has been measured at 50 °C. The volume of activation is −10.7 ± ~ 0.4 cm3 mole−1, essentially independent of solvent composition. Therefore, the partial volumes of both benzyl chloride and the transition state depend on solvent composition in the same way. The constant-volume energy and entropy of activation are simple functions of the solvent composition, and resemble the constant-volume parameters in ethanol–water mixtures. It is concluded that constant-volume conditions are probably more appropriate than constant-pressure conditions for discussing the solvent dependence of these solvolyses.

Reversible thermal denaturation of immobilized chymotrypsinogen

1979 ◽  
Vol 44 (10) ◽  
pp. 3090-3101
Author(s):  
Eduard Brynda ◽  
Miroslav Bleha
Keyword(s):  
Rate Constants ◽  
Thermal Denaturation ◽  
Physical Interaction ◽  
Native State ◽  
First Order ◽  
First Order Kinetics ◽  
Activated State ◽  
Equilibrium Data ◽  
Enthalpy And Entropy ◽  
As Effects

The reversible thermal denaturation of chymotrypsinogen A bound to the insoluble poly(2-hydroxyethyl methacrylate) Spheron matrix was investigated by the fluorescence method. The applicability of fluorescence data in the calculation of the thermodynamic parameters of denaturation was tested. Equilibrium data were obtained for immobilized chymotrypsinogen and chymotrypsinogen in solution at various pH in the range 2-6. The binding to Spheron shifts the thermodynamic equlibrium in favour of the denaturated state. An increase in pH above 3 did not affect the denaturation of immobilized chymotrypsinogen. The denaturation is controlled by the first-order kinetics. The rate constants and magnitudes of changes of free energy, enthalpy and entropy were calculated for the transition from the native state into the activated state, and from denaturated state into the activated state. The temperature dependence of the rate constants for the denaturation of immobilized chymotrypsinogen is qualitatively different from for chymotrypsinogen in solution. The results were interpreted as effects of the physical interaction between the denaturated protein and polymeric matrix.

Kinetics of Acid-Catalysed Hydrolysis of Diethylsuccinate in Dioxane-Water Mixtures

1982 ◽  
Vol 37 (4) ◽  
pp. 390-394
Author(s):  
Fayez Y . Khalil ◽  
F. M. Abdel-Halim ◽  
Adel N. Asaad
Keyword(s):  
Dielectric Constant ◽  
Thermodynamic Parameters ◽  
Rate Constants ◽  
Solvent Composition ◽  
Specific Rate ◽  
Molecular Dipole ◽  
First Order ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Activated Complex

Abstract The specific rate constants k1 and k2 of the consecutive first-order acid-catalysed hydrolysis steps of diethylsuccinate in dioxane-water mixtures covering the range 0-95% (w/w) of dioxane are determined at 25-55 °C. As the concentration of dioxane increases, the rate of the reaction decreases to a minimum at about 90% (w/w) dioxane, after which it increases again. The ratio k1/k2 was found to be almost constant at the value 2.0. The activation energies of the reaction are independent of solvent composition. Available electrostatic theories regarding the effect of the dielectric constant on the rate are presented, from which the reaction is shown to be an ion-molecular dipole type of interaction. The thermodynamic parameters and the radii of the activated complex at different solvent compositions are calculated and discussed.

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