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1.
Densities, ρ, viscosities, η, and refractive indices, nD, of glycine (Gly) (0.1 — 0.5 M) in aqueous 1,2‐ethanediol (1,2‐EtD), 1,2‐propanediol (1,2‐PrD), and 1,3‐butanediol (1,3‐BuD) (30% v/v) were measured at 298, 303, 308, and 313 K. Experimental values of ρ and η were used to calculate partial molar volumes, ?0v, partial molar volumes of transfer of Gly from water to aqueous diol solutions, ?0v(tr), Falkenhagen and Jones ‐Dole coefficients, A and B, respectively, free energies of activation of viscous flow, Δμ0*1 and Δμ0*2, per mole of solvent and solute, respectively, enthalpies, ΔH* and entropies, ΔS* of activation of viscous flow. Large positive values of ?0v, and an increasing value of Sv*, for all the three mixtures at each temperature suggest the presence of strong solute‐solvent interaction, and this interaction decreases as the size of alkyl moiety increases from 1,2‐EtD to 1,3‐BuD. Positive ?0v(tr) values tend to decrease with increasing the number of CH2 group, thereby indicating that the electrostriction effect in diols follows the sequence; 1,2‐EtD > 1,2‐PrD > 1,3‐BuD. Small A values, with large values of B, are indicative of weak solute‐solute and strong solute‐solvent interactions that operate in the present systems, and that the magnitudes of B are in the sequence: 1,2‐EtD > 1,2‐PrD > 1,3‐BuD and, thus, the sequence represents the strength of interaction between Gly and diol molecules. Moreover, positive SB/ST values suggest the structure‐breaking nature of Gly in diol + water mixtures. The observed values of Δμ0*2 fall in the sequence: 1,2‐EtD > 1,2‐PrD > 1,3‐BuD which, like ?0v and Sv*, reinforce that Gly‐diol interaction decreases with subsequent addition of CH2 group in diols. The trends in the variation of ΔH* and ΔS* with Gly concentration also reveal the presence of significant solute‐solvent interaction in all three systems. An almost linear increase in RD with an increasing amount of Gly reveals that Gly tends to increase the polarizability of the aqueous‐diol molecules under study. The variation of all these parameters with concentration of Gly and with temperature suggests the presence of strong solute‐solvent interaction, which decreases as the size of alkyl moiety in diols increases from 1,2‐EtD to 1,3‐BuD. 相似文献
2.
A. Ali P. Bidhuri 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(10):1668-1676
Apparent molar volumes, V ? for glycine (Gly) and glycylglycine (Gly-Gly) in aqueous D(+)-glucose and sucrose solutions have been determined from solution density, ρ measurements at 298.15, 303.15, 308.15, and 313.15 K as a function of the concentration of solutes (Gly and Gly-Gly). The standard partial molar volume, V ? 0 , transfer volume, ΔV ?(tr) 0 , for Gly and Gly-Gly from water to aqueous carbohydrate solutions, partial molar expansibility, E ? 0 , and hydration number, n H of solute have been calculated. The viscosity data have been analyzed by means of Jones-Dole equation to obtain A- and B-coefficients, free energy of activation of viscous flow per mole of solvent, Δμ 1 0# , and solute, Δμ 2 0# , enthalpy, ΔH 0#, and entropy of activation, ΔS 0# of viscous flow were evaluated. The behavior of these parameters has been interpreted in terms of solute-solute and solute-solvent interactions. 相似文献
3.
Gehan M. El-Subruiti Ghassan O. Younes Farah S. Zeitouni Mohamed F. Amira 《国际化学动力学杂志》2008,40(7):416-422
Kinetic studies of solvent structure effects and solute–solvent interactions on the solvolysis of [Co(NH3)5Cl]2+ complex ion have been investigated spectrophotometrically in binary aqueous mixtures. Three cosolvents were used (acetonitrile, dimethylsulfoxide, and urea) over a wide range of temperatures. Nonlinear plots were found for log(rate constant) against the reciprocal of the relative permitivity of the medium. The enthalpy and entropy of activation (ΔH# and ΔS#) exhibited extrema in the same composition region where the physical properties indicate sharp changes in the structure of the solvent, confirming that the solvent structure is an important factor in determining the solvolytic reactivity. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 416–422, 2008 相似文献
4.
Densities, ρ, viscosities, η, and refractive indices, n D, of glycine (Gly), DL-alanine (Ala), DL-valine (Val) (0.05, 0.10, 0.15, 0.20, 0.25 mol kg?1), and L-leucine (Leu) (0.02, 0.05, 0.10 mol kg?1) in water and in 0.20 mol kg?1 aqueous tetrapropylammonium bromide (TPAB) have been measured at 298.15, 303.15, 308.15, and 313.15 K. The density data have been utilized to calculate apparent molar volumes, ?v, partial molar volumes at infinite dilution, ?v°, and partial molar volumes of transfer, ? v°(tr) of amino acids. The viscosity data have been analyzed by means of Jones-Dole equation to obtain Falkenhagen coefficient, A, and Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δµ1°*, and solute, Δµ2°*, and enthalpy, ΔH*, and entropy of activation, ΔS*, of viscous flow. The refractive index data have been used to calculate molar refractivity, R D, of amino acids in aqueous tetrapropylammonium bromide solutions. It has been observed that ?v°, B-coefficient and Δµ2°* vary linearly with increasing number of carbon atoms in the alkyl chain of amino acids, and they were split to get contributions from the zwitterionic end groups (NH3 +, COO-) and methylene group (CH2) of the amino acids. The behavior of these parameters has been used to investigate the solute-solute and solute-solvent interactions as well as the effect of tetrapropylammonium cation (C3H7)4N+ on these interactions. 相似文献
5.
Timais Janz Manuel Güterbock Fabian Müller Dr. Martin Quick Dr. Ilya N. Ioffe Dr. Florian A. Bischoff Dr. Sergey A. Kovalenko 《Chemphyschem》2020,21(7):610-615
The solvent Stark effect on the spectral shifts of anthracene is studied with temperature-dependent solvatochromic measurements. The Stark contribution ΔvStark to the absorption shift Δvp in polar solvents is measured to be ΔvStark=(53±35) cm−1, in reasonable agreement with dielectric continuum theory estimate of 28 cm−1, whereas the major shift Δvp∼300 cm−1 presumably originates from the solute quadrupole. We pay attention to the accurate correction of Δvp for the nonpolar contribution that is crucial when the shifts are modest in magnitude. 相似文献
6.
《Physics and Chemistry of Liquids》2012,50(6):785-801
The apparent molar volume (?V), viscosity B-coefficient and molar refraction (RM) have been determined of L-valine in aqueous solution of LiCl, NaCl and KCl at 298 K, 303 K and 308 K from density (ρ), viscosity (η) and refractive index (nD) measurements, respectively. The limiting apparent molar volumes (?V0) and experimental slopes (SV*) derived from the Masson equation have been interpreted in terms of solute–solvent and solute–solute interactions, respectively. The viscosity data were analysed using the Jones–Dole equation and the derived parameter B has also been interpreted in terms of solute–solvent interactions in the solutions. Molar refraction (RM) has been calculated using the Lorentz–Lorenz equation. 相似文献
7.
《国际化学动力学杂志》2017,49(8):622-632
Synthesis and kinetics of potassium periodate(KIO4)/NaNO2/KHSO4)‐initiated nitration of aromatic compounds have been studied in aqueous acetonitrile medium. Synthesis of nitroaromatic compounds is achieved under conventional and solvent‐free microwave conditions. Reaction times in microwave‐assisted reaction are comparatively less than in conventional reaction. The reaction kinetics for the nitration of phenols in aqueous bisulfate and acetonitrile medium indicated first‐order dependence on [phenol], [NaNO2], and [KIO4]. An increase in [KHSO4] accelerated the rate of nitration under otherwise similar conditions. The rate of nitration increased in the solvent of high dielectric media (solvents with high dielectric constant (D )). Observed results were in accordance with Amis and Kirkwood plots [log k ′ vs. (1/D ) and [(D − 1)/(2D + 1)]. These observations probably indicate the participation of anionic species and molecular or (dipolar) species in the rate‐determining step. In addition, the plots of (log k ′) versus volume% of organic solvent were also linear, which probably indicate the importance of both electrostatic and nonelectrostatic forces, solvent–solute interactions during nitration of phenols. Reaction rates accelerated with the introduction of electron‐donating groups and retarded with electron‐withdrawing groups, but results could not be quantitatively correlated with Hammett's equation and depicted deviations from linearity. These deviations could probably be attributed to cumulative effects arising inductive, resonance, and steric effects. Leffler's plot (ΔH # vs. ΔS #) was found linear indicating the compensation (cumulative) effect of both enthalpy and entropy parameters in controlling the mechanism of nitration. 相似文献
8.
The kinetics of alkaline hydrolysis of 2‐chloro‐3,5‐dinitrobenzotrifluoride 1 and 1‐chloro‐2,4‐dinitrobenzene 2 were studied in various acetonitrile–water (AN–H2O) mixtures (10–90% w/w) at different temperatures. Thermodynamic parameters ΔH# and ΔS# show great variation, whereas ΔG# appears to vary little with the solvent composition presumably due to compensating variations. The results are discussed in terms of the solvent parameters such as preferential solvation, dielectric constant, polarity/polarizability, and hydrogen bond donor and acceptor parameters. It has been found that the factors controlling the reaction rates are the desolvation of OH?, the solvophobicity of the medium, and free water molecules in rich AN mixed solvent. The data showed that the solvatochromic parameters of (AN–H2O) mixed solvent are destroyed in the presence of excess OH?. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 453–463, 2010 相似文献
9.
Ibrahim Shehatta 《Helvetica chimica acta》2002,85(7):2125-2137
Dissociation constants (pKa) of trazodone hydrochloride (TZD⋅HCl) in EtOH/H2O media containing 0, 10, 20, 30, 40, 50, 60, 70, and 80% (v/v) EtOH at 288.15, 298.15, 308.15, and 318.15 K were determined by potentiometric techniques. At any temperature, pKa decreased as the solvent was enriched with EtOH. The dissociation and transfer thermodynamic parameters were calculated, and the results showed that a non‐spontaneous free‐energy change (ΔdissGo>0) and unfavorable enthalpy (ΔdissHo>0) and entropy (ΔdissSo<0) changes occurred on dissociation of trazodone hydrochloride. The free‐energy change or pKa varied nonlinearly with the reciprocal dielectric constant, indicating the inadequacy of the electrostatic approach. The dissociation equilibria are discussed on the basis of the standard thermodynamics of transfer, solvent basicity, and solute‐solvent interactions. The values of ΔtransGo and ΔtransHo increased negatively with increasing EtOH content, revealing a favorable transfer of trazodone hydrochloride from H2O to EtOH/H2O mixtures and preferential solvation of H+ and trazodone (TZD). Also, ΔtransSo values were negative and reached a minimum, in the H2O‐rich zone that has frequently been related to the initial promotion and subsequent collapse of the lattice structure of water. The pKa or ΔdissGo values correlated well with the Dimroth‐Reichardt polarity parameter ET(30), indicating that the physicochemical properties of the solute in binary H2O/organic solvent mixtures are better correlated with a microscopic parameter than the macroscopic one. Also, it is suggested that preferential solvation plays a significant role in influencing the solvent dependence of dissociation of trazodone hydrochloride. The solute‐solvent interactions were clarified on the basis of the linear free‐energy relationships of Kamlet and Taft. The best multiparametric fit to the Kamlet‐Taft equation was evaluated for each thermodynamic parameter. Therefore, these parameters in any EtOH/H2O mixture up to 80% were accurately derived by means of the obtained equations. 相似文献
10.
Density, viscosity, and refractive index, for glycine, DL-alanine, L-serine and DL-valine have been determined in aqueous solution of 0.05 mol/kg caffeine as a function of amino acid (AA) concentration at 25, 30, 35, and 40 ℃ The density data have been used to compute apparent molar volume. The partial molar volume (limiting apparent molar volume) was obtained by applying the Masson's equation. The viscosity data have been analyzed by means of Jones-Dole equation. The values of Falkenhagen coefficient and Jones-Dole coefficient thus obtained are used to interpret the solute-solute and solute-solvent interactions, respectively. Hydration number was also computed. The transition-state theory was applied to obtain the activation parameters of viscous flow, i.e., free energy of activation per mole of solvent, and solute. The enthalpy and entropy of activation of viscous flow were computed for the system. Refractive index was used to calculate molar refractivity of the mixtures. The results have been interpreted in the light of various interactions occurring between the components of the mixtures under applied experimental conditions. 相似文献
11.
Kinetics of the addition reaction of triphenylphosphine to para‐benzoquinone in 1,2‐dichloroethane as solvent was studied. Initial rate method was used to determine the order of the reaction with respect to the reactants. Pseudo‐first‐order method was also used to calculate the rate constant. This reaction was monitored by UV‐vis spectrophotometry at 520 nm by variable time method. On the basis of the obtained results, the Arrhenius equation of this reaction was obtained: The activation parameters, Ea, ΔH#, ΔG#, and ΔS# at 300 K were 5.701, 6.294, 19.958 kcal mol?1 and ?45.853 cal mol?1 K?1, respectively. This reaction is first and second order with respect to triphenylphosphine and para‐benzoquinone, respectively. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:472–479, 2004 相似文献
12.
Davood Nori‐Shargh Abolfazl Soofi Nasrin Saroogh Farahani Farzad Deyhimi 《国际化学动力学杂志》2005,37(7):427-433
This work reports the results of a kinetic and mechanistic investigations of the addition reaction of triphenylphosphine to para‐naphtoquinone in 1,2‐dichloromethane as solvent. The order of reaction with respect to the reactants was determined using initial rate method, and the rate constant was obtained on the basis of pseudo‐first‐order method. Variable time method using Uv–Vis spectrophotometry (at 400 nm) was utilized for monitoring this addition reaction, for which the following Arrhenius equation was obtained: The resulting activation parameters Ea, ΔH#, ΔG#, and ΔS# at 300 K were 13.63, 14.42, 18.75 kcal mol?1, and ?14.54 cal mol?1K?1, respectively. The results suggest that the reaction is first order with respect to both triphenylphosphine and para‐naphthoquinone. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 427–433, 2005 相似文献
13.
Davood Nori‐Shargh Bita Soltani Nasrin Saroogh‐Farahani Farzad Deyhimi 《国际化学动力学杂志》2006,38(2):144-151
The kinetics of the addition reaction of aniline to ethyl propiolate in dimethylsulfoxide (DMSO) as solvent was studied. Initial rate method was used to determine the order of the reaction with respect to the reactants, and pseudo‐first‐order method was used to calculate the rate constant. This reaction was monitored by UV–Vis spectrophotometer at 399 nm by the variable time method. On the basis of the experimental results, the Arrhenius equation for this reaction was obtained as log k = 6.07 ‐ (12.96/2.303 RT). The activation parameters, Ea, ΔH#, ΔG#, and ΔS# at 300 K were 12.96, 13.55, 23.31 kcal mol?1 and ?32.76 cal mol?1 K?1, respectively. The results revealed a first‐order reaction with respect to both aniline and ethyl propiolate. In addition, based on the experimental results and using also density functional theory (DFT) at B3LYP/6‐31G* level, a mechanism for this reaction was proposed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 144–151, 2006 相似文献
14.
The viscosities, η, and refractive indices, n, of pure dimethylsulphoxide (DMSO), benzene, toluene, o‐xylene, m‐xylene, p‐xylene and mesitylene, and those of their 54 binary mixtures, with DMSO as common component, covering the whole composition range have been measured at 298.15, 303.15, 308.15, 313.15, and 318.15 K. From the experimental data, the deviations in viscosity, Δη and deviations in molar refraction, ΔRm have been calculated. The variation of these parameters with composition and temperature of the mixtures have been discussed in terms of molecular interaction in these mixtures. The effect of the number and position of the methyl groups in these aromatic hydrocarbons on molecular interactions in these mixtures has also been discussed. The free energies, ΔG*, enthalpies, ΔH* and entropies, ΔS* of activation of viscous flow have also been obtained by using Eyring viscosity equation. The ΔH* values were found independent of temperature. The dependence of these thermodynamic parameters on composition of the mixtures has been discussed. Further, the viscosities and refractive indices of these binary mixtures were calculated theoretically from pure component data by using various empirical and semi‐empirical relations and the results were compared with the experimental findings. 相似文献
15.
Sudhakar S. Dhondge Chandrashekhar P. Pandhurnekar Dilip V. Parwate 《The Journal of chemical thermodynamics》2009,41(5):577-585
Experimental results of density (ρ), speed of sound (u), and refractive index (nD) have been obtained for aqueous solutions of ethylene glycol monomethyl ether (EGMME), ethylene glycol monoethyl ether (EGMEE), diethylene glycol monomethyl ether (DEGMME), and diethylene glycol monoethyl ether (DEGMEE) over the entire concentration range at T = 298.15 K. From these measurements, the derived parameters, apparent molar volume of solute (?V), excess molar volume (VE), isentropic compressibility of solution (βS), apparent molar isentropic compressibility of solute (?KS), deviation in isentropic compressibility (ΔβS), molar refraction [R]1,2 and deviation in refractive index of solution (ΔnD) have been calculated. The Redlich–Kister equation has been fitted to the calculated values of VE, ΔβS and ΔnD for the solution. The results obtained are interpreted in terms of hydrogen bonding and various interactions among solute and solvent molecules. 相似文献
16.
Gehan M. El‐Subruiti Ghassan O. Younes Farah S. Zeitouni Mohamed F. Amira 《国际化学动力学杂志》2004,36(9):494-499
The kinetics of aquation of bromopentaamine cobalt(III) complex have been investigated spectrophotometrically in aqueous‐organic solvent media using acetonitrile, urea, and dimethyl sulfoxide as co‐solvents at 45 ≤ T (°C) ≤ 65. The logarithms of rate constant of the aquation reaction vary nonlinearly with the reciprocal of the dielectric constant for all cosolvent mixtures, indicating a specific solute–solvent interaction. Also, the rate constants are correlated with the total number of moles of water and the organic solvents. However, the solvent effects on the solvation components of the enthalpy of activation, ΔH?, and the entropy of activation, ΔS?, have been studied. Analysis of the solvent effect confirmed a common Id mechanism for the aquation of the cobalt(III) complex. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:494–499, 2004 相似文献
17.
The kinetics of SN2 reaction between phenacyl bromide and various amines in 12 different solvents were studied. Solvent effects on the rate of this reaction and free energy of activation, ΔG# , were interpreted by applying the Abraham-Kam-let-Taft (AKT) equation. UK solvent polarity (π1*), solvent hydrogen-bond basicity (β1) and Hildebrand cohesive density energy (δH2) are those parameters which increase the rate constant and decrease ΔG# , while solvent hydrogen-bond acidity (α1) will have the compensatory effect. A comparison among obtained values of second rate constants, k2, for different amines in a given solvent indicates that the amine reactivities are highly dependent on their structures. The consequent decrease of the rate constant for different amines in any given solvent was found to be: primary > secondary> tertiary. This order results from steric effects of amines. 相似文献
18.
The aerial oxidation kinetics of hydroquinone in a freshly prepared developer solution at different temperatures and pHs has been studied. The activation parameters, Ea, ΔG# , ΔS# , ΔH# and enthalpy of formation of activated complex, ΔHfo(X# ), are determined. The large negative value of free energy of activation ΔG# proves that hydroquinone extremely tends to be oxidized by air at optimum temperature (20℃) and optimum pH (10.5) and converts to the activated complex semiquinone. It was also found that if the pH of the developer solution is increased from 9.3 to 10.5 the reaction rate will increase by a factor of 2. 相似文献
19.
Kinetics of the substitution reaction of solvent molecule in uranyl(VI) Schiff base complexes by tri‐n‐butylposphine as the entering nucleophile in acetonitrile at 10–40°C was studied spectrophotometrically. The second‐order rate constants for the substitution reaction of the solvent molecule were found to be (8.8 ± 0.5) × 10?3, (5.3 ± 0.2) × 10?3, (7.5 ± 0.3) × 10?3, (6.1 ± 0.3) × 10?3, (13.5 ± 1.6) × 10?3, (13.2 ± 0.9) × 10?3, (52.9 ± 0.2) × 10?3, and (88.1 ± 0.6) × 10?3 M?1 s?1 at 40°C for [UO2(Schiff base)(CH3CN)], where Schiff base = L1–L8, respectively. In a temperature dependence study, the activation parameters ΔH# and ΔS# for the reaction of uranyl complexes with PBu3 were determined. From the linear rate dependence on the concentration of PBu3, the span of k2 values and the large negative values of the activation entropy, an associative (A) mechanism is deduced for the solvent substitution. By comparing the second‐order rate constants k2, it was concluded that the steric and the electronic properties of the complexes were important for the rate of the reactions. 相似文献
20.
《Fluid Phase Equilibria》1999,157(2):317-342
Kinematic viscosities (ν) of the ternary ethane-1,2-diol (1)+2-methoxyethanol (2)+water (3) solvent system have been measured for 36 ternary mixtures covering the whole miscibility range expressed by the condition 0<X1,X2,X3<1, at 19 temperatures in the range −10≤t (°C)≤80. The measured values have been used to test some empirical equations of the type ν=ν(t) and ν=ν(Xi), in order to provide for useful interpolation procedures to obtain calculated values in correspondence to the experimental data gaps. From the experimental data, the excess kinematic viscosities (νE) have been calculated. Sign and magnitude of these quantities have been discussed in terms of type and nature of specific intermolecular interactions. Furthermore, derived quantities such as thermodynamic parameters of the viscous flow (ΔG*, ΔH* and ΔS*), have been analysed on the basis of the Eyring's model. All the investigated excess mixing properties indicate the probable absence of stable three-component adducts in this ternary solvent system. 相似文献