scholarly journals Studies on the effect of Aquo-Dioxan Solvent System on the biochemical behaviour of the Substituted Valerates

2020 ◽  
Vol 16 (5) ◽  
pp. 63-71
Author(s):  
SUSHMA KUMARI ◽  
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Hydrolysis Product ◽  
Solvent System ◽  
Simultaneous Increase ◽  
Solute Interaction ◽  
Reaction Media ◽  
Energy Activation

Valerates and Substituted Valerates have been found to be useful for humanbeings as its hydrolysis product i.e. valence acid is used in the society in the form of perfumes flavours platister, vinyl stabilizer and pharmaceuyicals. With a views to study the solvent effect of 1:4 dioxan on the biochemical behivour of the hydrolysis product of a substituted valerate, the kinetic of Alkali catalysed of mothyl iso-valerate was studies in aquodioxan media. Increase observed in free energy activation with simultaneous increase in the value of both the activation H* and S*, it is concluded that in the presence of dioxan with reaction media, the reaction becomes enthaipy dominating and entropy controlled. From the evaluated values of the reaction which comes to be 329.0, it is inferred that Barclay-Butler rule is obeyed by the reaction and there is strong solvent- solute interaction in presence of dioxan the reaction media.

ENTROPY-ENTHALPY COMPENSATION BEHAVIOR REVISITED

2004 ◽  
Vol 03 (04) ◽  
pp. 511-520 ◽  
Author(s):  
WILLIAM R. KIRK
Keyword(s):  
Free Energy ◽  
Statistical Mechanics ◽  
Solvent Effect ◽  
Liquid State ◽  
Compensation Behavior ◽  
Solute Interaction ◽  
Entropically Driven ◽  
Thermodynamic Perturbation

The origin of genuine (not statistically spurious) entropy-enthalpy compensation is investigated within standard liquid state statistical mechanics formalism. We treat two extreme cases of solvent-solute interaction: (1) those in which the changes "internal" to the solute dominate, and (2) those in which the solvent effect is dominant. They are evaluated in different ways, and lead to different predictions for compensation behavior. The first involves a conventional "thermodynamic perturbation" formalism.1,2 The second case leads to an Ornstein–Zernicke-like relationship that predicts predominantly entropically driven changes in free energy of reaction.

scholarly journals Studies on the effect of Dielectric constants of Aquo-DMF Solvent- System of the Solvolysis Products of Nicotinates

2020 ◽  
Vol 16 (5) ◽  
pp. 72-77
Author(s):  
RENU KUMARI ◽  
◽  
R.T. SINGH ◽  
Keyword(s):  
Solvent System ◽  
Dielectric Constants ◽  
Dimethyl Formamide ◽  
Kinetic Temperature ◽  
Methyl Nicotinate ◽  
Increase With Increase ◽  
Solute Interaction ◽  
Simultaneous Decrease ◽  
Reaction Media ◽  
Activated Complex

From the eenhancement observed in G* values with simultaneous decrease in the values of H and S* of the reaction, it is concluded that the organic co-solvent dimethyl formamide (DMF) acts as entropy controller and enthalpy stimulator solvent for alkali catalysed solvolysis of Methyl nicotinate. Form the evaluated values of water molecules associated with the activated complex of the reaction which are found to increase with increase in the temperature of the reaction, it is inferred that the bimolecular mechanistic path is changed to unimolecular in presence of the organic component (DMF) of the reaction media. The numerical value of Iso-Kinetic temperature of the reaction which comes to be nearly 287.5 (below 300) indicates that there is weak but considerable solvent-solute interaction in the aquo-DMF solvent system.

Kinetics of Ion-Pair Effect of Aquation of Bromopentaammine Cobalt(III) Complex in Different Dicarboxylate Media

2011 ◽  
Vol 324 ◽  
pp. 166-169 ◽  
Author(s):  
Farah Zeitouni ◽  
Gehan El-Subruiti ◽  
Ghassan Younes ◽  
Mohammad Amira
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Compensation Effect ◽  
Ion Pairing ◽  
Reaction Rates ◽  
Ion Pair ◽  
Free Energy Of Activation ◽  
Different Types ◽  
Different Temperatures ◽  
Kinetics Of

The rate of aquation of bromopentaammine cobalt(III) ion in the presence of different types of dicarboxylate solutions containing tert-butanol (40% V/V) have been measured spectrophotometrically at different temperatures (30-600°C) in the light of the effects of ion-pairing on reaction rates and mechanism. The thermodynamic and extrathermodynamic parameters of activation have been calculated and discussed in terms of solvent effect on the ion-pair aquation reaction. The free energy of activation ∆Gip* is more or less linearly varied among the studied dicarboxylate ion-pairing ligands indicating the presence of compensation effect between ∆Hip* and ∆Sip*. Comparing the kip values with respect of different buffers at 40% of ter-butanol is introduced.

Thermodynamic studies in solution. Part IV. Solvent effect on the solvolysis of tert-butyl chloride. A new treatment of the experimental data

1979 ◽  
Vol 57 (5) ◽  
pp. 500-502 ◽  
Author(s):  
Joaquim Jose Moura Ramos ◽  
Jacques Reisse ◽  
M. H. Abraham
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Free Energies ◽  
Butyl Chloride ◽  
Activation Free Energy ◽  
Tert Butyl ◽  
New Treatment ◽  
The One ◽  
Activated Complex ◽  
Tert Butyl Chloride

A new treatment of the solvent effect on the solvolysis of tert-butyl chloride is proposed. This treatment is based on activation free energy measurements and on transfer free energy measurements of the reactant (R) on the one hand and of a model (M) of the activated complex (AC) on the other hand. Solute–solvent interaction free energies for the reactant, the activated complex and the model compound are estimated. This estimation involves the calculation of the free energy of cavity formation of these various solutes (R, AC, and M) in all the solvents. These cavity terms, which are a function of the cohesive properties of the solvent and of the surface of the cavity do not reflect the electronic structure of the solute whereas the interaction free energy term does. The method we propose can be described as a new 'experimental' approach for the study of the charge separation in an activated complex.

A reaction density functional theory study of the solvent effect in prototype SN2 reactions in aqueous solution

2019 ◽  
Vol 21 (45) ◽  
pp. 24876-24883 ◽  
Author(s):  
Cheng Cai ◽  
Weiqiang Tang ◽  
Chongzhi Qiao ◽  
Peng Jiang ◽  
Changjie Lu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Density Functional Theory ◽  
Free Energy ◽  
Solvent Effect ◽  
Density Functional ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Sn2 Reactions ◽  
Energy Profiles ◽  
Free Energy Profiles

Reaction density functional theory (RxDFT), combining quantum DFT with classical DFT, has been employed to investigate the solvent effect and free energy profiles of SN2 reactions in aqueous solution.

Kinetic medium effects. III. Solvent effects on A1 and A2 Hydrolyses in water-dimethyl sulphoxide mixtures

1967 ◽  
Vol 20 (9) ◽  
pp. 1815 ◽  
Author(s):  
BG Cox ◽  
PT McTigue
Keyword(s):  
Ethyl Acetate ◽  
Solvent Effect ◽  
Activity Coefficients ◽  
Solvent Effects ◽  
Butyl Acetate ◽  
Solvent System ◽  
Solvent Composition ◽  
Dimethyl Sulphoxide ◽  
Medium Effects ◽  
System Activity

The relative rates of the concurrent A1 and A2 hydrolyses of t-butyl acetate have been measured as a function of solvent composition in water-dimethyl sulphoxide (DMSO) mixtures. A large difference in solvent effect is observed, which correlates well with observed solvent effects on ethyl acetate (A2) and acetal (Al) hydrolyses in the same solvent system. Activity coefficients have been measured for t-butyl acetate, ethyl acetate, and acetal in various water-DMSO mixtures.

Studies on the iodide–triiodide equilibrium

1977 ◽  
Vol 55 (5) ◽  
pp. 792-797 ◽  
Author(s):  
Robert L. Benoit ◽  
Michael F. Wilson ◽  
Sing-Yeung Lam
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Gas Phase ◽  
Formation Enthalpy ◽  
Aprotic Solvents ◽  
Free Energies ◽  
Potentiometric Measurements ◽  
Cast Doubt ◽  
Transfer Parameters ◽  
The Enthalpy Of Formation

The solvent effect on the iodide–triiodide equilibrium has been investigated by means of calorimetric and potentiometric measurements. The aprotic solvents studied were nitromethane, nitrobenzene, sulfolane, acetonitrile, propylene carbonate, acetophenone, dimethylformamide, dimethylsulfoxide, and o-dichlorobenzene. The resulting enthalpy and free energy changes imply that the variations of the enthalpies and free energies of transfer of the iodide and triiodide ions probably are small and that there is an important non-coulombic contribution to these transfer parameters. Values were obtained for the enthalpy of formation of two solid triiodides, which together with values for other triiodides, cast doubt on reported calculated lattice enthalpies of triiodides and formation enthalpy of I3− ion in the gas phase. This latter formation enthalpy is found to be, from our solution data, more negative than −22 kcal mol−1.

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