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1.
The thermodynamic functions of complex formation of benzo-15-crown-5 ether (B15C5) and sodium cation (Na+) in the mixtures of propan-1-ol (PrOH) with water at 298.15 K have been calculated from experimental measurements. The equilibrium constants of B15C5/Na+ complex formation have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured by a calorimetric method. The complexes are enthalpy stabilized but entropy destabilized in the PrOH–H2O mixtures. The effects of preferential solvation of B15C5 by molecules of the organic solvent, solvation of the sodium cation, as well as the acid-base properties of propan-1-ol–water mixtures on the complex formation processes are discussed. 相似文献
2.
Małgorzata Jóźwiak 《Journal of Thermal Analysis and Calorimetry》2010,101(3):1039-1045
The enthalpies of solution of cyclic ethers: 1,4-dioxane, 12-crown-4 (12C4), and 18-crown-6 (18C6) in water–acetone mixtures
have been measured within the whole mole fraction range at 298.15 K. Based on the obtained data, the effect of base–acid properties
of water–acetone mixtures on the solution enthalpy of cyclic ethers in this mixed solvent has been analyzed. The strong dependence
of the enthalpy of solution (solvation) of cyclic ethers on basic properties of mixed solvent has been observed. The effects
of carbonyl atom replacement in acetone (ACN) molecule by sulfur atom (DMSO molecule) and base–acid properties of mixed solvent
on the solvation process of cyclic ethers have been analyzed. 相似文献
3.
Enthalpies of dissolution of benzo-15-crown-5 ether (B15C5) in mixtures of acetonitrile with water and in solutions of NaI and NaBPh4 (I=0.05 mol dm–3) in these mixtures were measured at 298.15 K. From the obtained results and appropriate literature data, the thermodynamic functions of B15C5/Na+ complex formation in acetonitrile-water mixtures were determined. The enthalpies of transfer of the complex B15C5/Na+ from pure acetonitrile to the examined mixtures were calculated and are discussed. 相似文献
4.
Małgorzata Jóźwiak 《Journal of Thermal Analysis and Calorimetry》2008,93(3):701-705
Enthalpies of solution of 1,4-dioxane, 12-crown-4 ether (12C4), 15-crown-5 ether (15C5) and 18-crown-6 (18C6) have been analyzed
from the point of view of preferential solvation of these cyclic ethers (crown ethers) by a molecule of acetone or dimethylsufoxide
in the mixtures of water with acetone or dimethylsulfoxide. It has been observed that the carbonyl carbon atom replacement
in acetone molecule by sulfur atom brings about completely different behavior of molecules of these solvents in relation to
cyclic ethers dissolved in mixed solvents. Crown ethers are preferentially solvated by acetone (ACN) molecules, which is not
observed in the case of dimethylsulfoxide (DMSO). 相似文献
5.
Małgorzata Jóźwiak 《Journal of solution chemistry》2002,31(7):589-599
Enthalpies of solution of 15-crown-5 ether in the acetonitrile–water–sodium iodide system have been measured at 25°C. The equilibrium constants of complex formation of 15C5 with sodium iodide have been determined by molar conductance at various mole ratios 15C5 to sodium iodide in mixtures of water with acetonitrile at 25°C. The thermodynamic functions for complexation of the crown ether with Na+ were calculated. From the result, the standard Gibbs energies of complex formation as a function of the normalized Lewis acidity parameters E
N
T and enthalpy of solvation of 15C5 in the mixtures of water with acetonitrile have been analyzed. The enthalpies of transfer of the 15C5 complex with sodium iodide from pure acetonitrile to the mixtures studied were calculated and discussed. 相似文献
6.
Małgorzata Jóźwiak 《Journal of solution chemistry》2003,32(12):1019-1031
The equilibrium constants of complex formation of benzo-15-crown-5 ether with sodium ion have been determined by molar conductance at various molar ratios of benzo- 15-crown-5 ether and sodium iodide in mixtures of water with acetonitrile at 298.15 K. The thermodynamic quantities of complex formation of benzo-15-crown-5 ether with sodium cation are calculated. The enthalpy of solvation of benzo-15-crown-5 ether and sodium ion complex is discussed together with solvation enthalpies of the cation and ligand. The contribution of the benzene ring to the thermodynamic properties of complex formation and to the enthalpy of solvation of the crown ether/ Na+ complex in the mixtures of water with acetonitrile are analyzed and discussed. 相似文献
7.
Abdolraouf Samadi-Maybodi S. Masoomeh Pourali Mohsen Tafazzoli 《Journal of solution chemistry》2009,38(2):159-169
27Al NMR spectroscopy is a powerful tool for the study of coordination and solvation in both aqueous and nonaqueous solutions.
In this study, the complexes coexisting upon dissolution of AlCl3 in acidic acetone + methanol solutions are shown to consist essentially of mixed hexacoordinated species of the general formula
[Al(CH3OH)6−n
(CH3COCH3)
n
]3+ (n=1,2 and 3), all exhibiting distinctly different 27Al shielding effects. The relative populations of the various mixed species are found to be highly dependent upon the acetone:methanol
mole ratio that in the more acetone-rich mixtures with aluminum become appreciably coordinated by acetone. The results demonstrate
that the key factor for the formation of acetone-containing species in acidic methanolic solutions is having the CH3COCH3:CH3OH mole ratio at 3:1. 相似文献
8.
Zaitseva I. S. Grigor'eva N. Yu. El'tsov S. V. Bondarev N. V. 《Russian Journal of General Chemistry》2001,71(4):505-511
Stability constants of Na+ complexes with 18-crown-6-ether and thermodynamic characteristics of the complex formation in water and mixed water-dioxane solvents (0.2, 0.4, 0.6, and 0.8 wt. fraction of dioxane, 283-318 K) were determined by the method of EMF of galvanic circuits without transfer. Comparative thermodynamic analysis of the complex 18-crown-6Na+ formation reactions in water-dioxane, water-acetonitrile, water-acetone, water-methanol, and water-2-propanol mixtures was carried out. Contributions of the Gibbs energies of transfer (G
t) of 18-crown-6Na+, Na+, and the ligand to the increase in the stability of the complexes on replacement of water by mixed water-dioxane solvents were estimated. It was shown that the increase in the stability of sodium crown ether complexes primarily depends on solvation of the complex cation and desolvation of the central cation. Changes in the conformational Gibbs energy of the ligand and quantitative parameters of selective solvation of the reagents were estimated. 相似文献
9.
The enthalpies of solution of benzo-15-crown-5 ether in methanol–water mixtures and methanol–water–sodium iodide systems have
been measured at 298.15 K. The values of standard enthalpies of solution of benzo-15-crown-5 ether are positive in the mixtures
of water and methanol within the whole range of mixture composition. The equilibrium constants of complex formation of benzo-15-crown-5
ether with the sodium cation have been determined by conductivity measurements at 298.15 K. The thermodynamic functions of
the formation of these complexes have been calculated. The Gibbs energy of complex formation depends on the base–acid properties
of methanol–water mixture. 相似文献
10.
The enthalpies of solution of sodium iodide in methanol, ethanol and acetone and in mixtures of methanol and ethanol with water were measured over wide ranges of electrolyte concentration and temperature. Standard enthalpies of solution, transfer enthalpies of NaI from alcohols to alcohol-water mixtures, and temperature coefficients of enthalpies of solution have been calculated. Thermodyanmic characteristics of solution and solvation of the Na+ and I– ions in acetone and ethanol were determined at 243–298 K. It is noted that at lower temperatures the disruption of solvent structure by ions is a local effect. The presence of negative solvation of the Na+ and I– ions in alcohol-water mixtures at lower temperatures is demonstrated. 相似文献
11.
Quantum chemical modeling of Li+ ion transfer from the solvation shell of γ-butyrolactone (GBL) as the solvent to the cavity of 15-crown-5 (15C5) macrocyclic
ligand was carried out. Calculations were performed using the PBE nonempirical density functional and an extended basis for
the SBK pseudopotential. The solvation energy was included in the framework of the polarizable continuum model. The calculated
geometric parameters of GBL and 15C5 molecules are in good agreement with experimental X-ray data. The energies and structures
of the Li(GBL)
n
+ (n = 1–5) complexes and Li(GBL)
m
(15C5)+ (m = 0–3) mixed complexes were calculated. The binding energy of the fifth GBL molecule is low; therefore, the Li+ ion is mainly surrounded by four GBL molecules. The formation of mixed complexes by consecutive displacement of GBL molecules
from the solvation shell of the lithium ion leads to structures with the coordination number 5. The equilibrium constants
of these processes were used to determine the dependence of the composition of the solvation complexes on the concentration
of 15C5 in the system. The concentrations of the Li(15C5)+ and Li(GBL)(15C5)+ complexes appeared to be comparable. The revealed structural features of the Li+ solvation complexes in the GBL-15C5 system were used to analyze the operating efficiency of lithium power sources. 相似文献
12.
V. Thiagarajan V.K. Indirapriyadharshini P. Ramamurthy 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):309-313
23Na NMR measurements were employed to monitor the stability of Na+ ion complexes with 18-crown-6 (18C6), dicycloxyl-18-crown-6 (DC18C6), dibenzo-18-crown-6 (DB18C6), 15-crown-5 (15C5) and benzo-15-crown-5 (B15C5) in binary acetonitrile–dimethylformamide mixtures of varying composition. In all cases, the variation of 23Na chemical shift with [crown]/[Na+] mole ratios indicated the formation of 1:1 complexes. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data to an equation which relates the observed chemical shifts to the formation constants. It was found that, in pure acetonitrile, the stabilities of the resulting 1:1 complexes vary in the order 15C5>DC18C6>B15C5>18C6>DB18C6, while in pure dimethylformamide the stability order is DC18C6>18C6>15C5>B15C5>DB18C6. The observed changes in the stability order could be related to the specific interactions between some crown ethers and acetonitrile. It was found that, in the case of all complexes, an increase in the percentage of dimethylformamide in the solvent mixtures would significantly decrease the stability of the complexes. 相似文献
13.
I. A. Kuz’mina V. A. Sharnin A. N. Golikov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(6):946-949
The influence of the composition of acetonitrile-dimethylsulfoxide solvents on the stability of silver(I) complexes with 18-crown-6
ether was studied potentiometrically. An increase in the concentration of dimethylsulfoxide decreased the stability of the
coordination compound. It was shown on the basis of the thermodynamic characteristics of solvation of the reagents that a
determining factor of complex formation equilibrium shifts was the solvation effect of the Ag+ ion. An equation was suggested for predicting the stability of silver(I) coordination compounds with crown ethers and pyridine-type
ligands in binary mixtures of aprotic solvents from changes in the solvation state of the central ion. 相似文献
14.
Mirosław S. Gruszkiewicz Donald A. Palmer Ronald D. Springer Peiming Wang Andrzej Anderko 《Journal of solution chemistry》2007,36(6):723-765
A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing
the Na+, K+, Mg2+, Ca2+, Cl− and NO3− ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework
has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 °C
and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination
of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 °C. The measurements
have been performed using Oak Ridge National Laboratory’s (ORNL) previously designed gravimetric isopiestic apparatus, which
can also detect solid phase precipitation. In addition to various Na–K–Mg–Ca–Cl–NO3 systems, results are reported for LiCl solutions. Water activities are reported for mixtures with a fixed ratio of salts
as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two
fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence
of solid–liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data
for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor–liquid and solid–liquid
equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems. 相似文献
15.
H. N. Altshuler L. P. Abramova N. V. Malyshenko G. Yu. Shkurenko E. V. Ostapova 《Russian Chemical Bulletin》2005,54(8):1978-1981
The ion-exchange equilibrium in network polymers obtained from cis-2,8,14,20-tetraphenyl-4,6,10,12,16,18,22,24-octahydroxycalix[4]arene by template synthesis on cations Na+, K+, and Ba2+ as matrices was studied. The selectivity coefficients of ion exchanges Ba2+-H+, Na+-H+, K+-H+, Na+-K+, and Na+-NH4
+ were determined. The template synthesis enhanced the affinity of the polymers to matrix-forming cations by 6–8 kJ mol−1.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1919–1922, August, 2005. 相似文献
16.
Małgorzata Jóźwiak 《Journal of solution chemistry》2004,33(9):1073-1084
The equilibrium constants of complex formation of 15-crown-5 and benzo-15-crown-5 ethers with the sodium cation have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured by a calorimetric method at 298.15 K. The thermodynamic functions of complex formation of 15-crown-5 and benzo-15-crown-5 ethers with the sodium cation in the mixtures of water with hexamethylphosportriamide at 298.15 K have been calculated. The extent of complex formation in this mixed solvent depends on the enthalpic effect. In water–hexamethylp- hosportriamide mixtures with medium and low water content, the complex of crown ethers with the sodium cation is not formed because of the strong solvation of sodium cation and crown ethers molecules; this implies that the entropy of complex formation is more negative than the enthalpy of complex formation. 相似文献
17.
Extraction of microamounts of cesium by nitrobenzene solutions of sodium dicarbollylcobaltate (Na+B−), potassium dicarbollylcobaltate (K+B−) and rubidium dicarbollylcobaltate (Rb+B−) in the presence of polypropylene glycol PPG 425 (L) has been investigated. The equilibrium data have been explained assuming
that the complex species ML+ (M+ = Na+, K+, Rb+, Cs+; L = PPG 425) are present in the organic phase. The stability constants of the cationic complex species ML+ (M+ = Na+, K+, Rb+) in nitrobenzene saturated with water have been determined; they were found to increase in the series of Rb+ < K+ < Na+. 相似文献
18.
Proton NMR was used to study the complexation reaction of Li+ and Na+ ions with 15-Crown-5 (15C5) in a number of binary acetonitrile (AN)-nitrobenzene (NB) mixtures at different temperatures. In all cases, the exchange between free and complexed 15C5 was fast on the NMR timescale and only a single population average 1H signal was observed. The formation constants of the resulting 1:1 complexes in different solvent mixtures were determined by computer fitting of the chemical shift mole ratio data. There is an inverse relationship between the complex stability and the amount of AN in the solvent mixtures. The enthalpy and entropy values for the complexation reaction were evaluated from the temperature dependence of the formation constants. In all the solvent mixtures studied, the resulting complex is enthalpy stabilized but entropy destabilized. Finally, the experimental results were compared with theoretical ones that were obtained from molecular modeling methods. Based on our results, it is most probable that Li+-15C5 in solvent stays in a rather nesting complex form with greater LogKf values, but Na+-15C5 forms a complete perching complex form with lower LogKf values. 相似文献
19.
Ma?gorzata Jó?wiak 《Thermochimica Acta》2004,417(1):27-30
Enthalpy of solution of crown ethers (15-crown-5 and benzo-15-crown-5) in water-acetone mixtures have been measured within the whole range of mole fraction at 298.15 K. The obtained data have been compared with those of the solution enthalpy of both crown ethers in the mixtures of water with dimethyl sulfoxide. The replacement of SO group with CO in the molecule of the organic solvent brings about an increase in the exothermic effect of the solution of 15-crown-5 and benzo-15-crown-5 ethers, especially in the mixtures with a medium water content. The observed effect is connected with the preferential solvation of the molecules of both crown ethers by acetone molecules in the water-acetone mixtures. The process of preferential solvation of 15-crown-5 and benzo-15-crown-5 ethers does not take place in the water-dimethyl sulfoxide mixture. 相似文献
20.
Usacheva T. R. Lendencov S. F. Sharmin V. A. 《Journal of Thermal Analysis and Calorimetry》2002,70(1):209-216
The thermodynamic parameters (DrG0, Dr
H
0, TDr
S
0) of the reaction of [Ag18C6]+ complex formation were obtained for a wide range of H2O-DMSO mixtures from the calorimetric data at 298.15 K. The relation between the thermodynamic parameters of complex formation
and solvation of each reagent was investigated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献