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1.
Sachiko Sakura 《Journal of Electroanalytical Chemistry》1977,80(2):315-324
Polarographic reductions of various metal ions such as the silver, cupric, zinc, cobaltous, nickel, ferric, ferrous ions and hydrogen ion in hexamethylphosphoramide (HMPA), have been investigated in the supporting electrolytes with various perchlorates. The reduction of most of these ions is strongly influenced by the cation of the supporting electrolyte. In the presence of the tetraethylammonium ion, when the size of the cation of the supporting electrolyte is small and easily adsorbed on the negatively charged electrode surface, the reductions of metal ions are controlled by some preceding processes and are naturally irreversible. The rate of reduction becomes more rapid with the increase of the size of the cation. Thus, in Hex4NClO4 or LiClO solutions, the reduction of these various metal ions takes place almost totally under diffusion control, although the waves of most of metal ions show a maximum. These effects of the cation of the supporting electrolytes on reduction can be explained as a phenomenon occurring on the electrode surface. This phenomenon has been reported in previous papers [1] on the reductions of the alkali and alkaline earth metal ions. The difference in the electrocapillary curves in these solutions is rarely shown at the potential around the electrocapillary maximum, but it is very obviously shown at more negative potential. The difference in the effect of the size of the cation of the supporting electrolyte on reduction of metal ion coincides well with the difference in the electrocapillary curves in these solutions: the effect of the size of the supporting electrolyte cation on the polarographic reduction is rarely shown at the potential around the electrocapillary maximum, but it is very obviously shown at more negative potential; therefore this effect is due to the electrode double-layer difference. 相似文献
2.
Shoichi Katsuta Takuya Ishitani Mika Suzuki Yuki Ishii Yoshihiro Kudo Yasuyuki Takeda 《Journal of solution chemistry》2004,33(5):437-451
The 1:1 ion-pair formation constants (K
IP) of tetraalkylammonium (Me4N+, Et4N+, Pr4N+, Bu4N+, and Bu3MeN+) picrates in water were determined by capillary electrophoresis at 25°C. The ion-pair extraction constants (K
ex,ip) of the picrates from water to m-xylene were determined by a batch-extraction method at 25°C, and the distribution constants (K
D) of the neutral ion-pairs were calculated from the relationship K
D = Kex,ip/K
IP. The tetraalkylammonium ion having more methylene groups generally forms a slightly more stable ion-pair with the picrate ion in water, which is attributed to the lower hydration of the cation. For Me4N+, Et4N+, Pr4N+, and Bu4N+, the distribution of the ion pair into m-xylene increases in that order, and a linear relationship was found between log K
D and the number of methylene groups in the cation. This is consistently explained by the regular solution theory. It was also revealed that the ion pairs have a strong specific interaction with water. The ion pair of Bu3MeN+ has a higher distribution constant than that expected from the relationship between log K
D and the number of methylene groups for the symmetrical tetraalkylammonium ions. The cation dependence of the ion pair extractability is mostly governed by that of the distribution of the ion pair. 相似文献
3.
E. V. Stenina L. N. Sviridova B. B. Damaskin 《Russian Journal of Electrochemistry》2008,44(7):772-778
The electrochemical behavior of cryptand[2.2.2] (Cry) is studied on a mercury electrode in aqueous solutions of tetraalkylammonium tetrafluoroborates (Me4N+, Et4N+, and Bu4N+). Cryptand [2.2.2] is shown to exhibit high surface activity in Me4 NBF4 nd Et4NBF4 solutions. Based on the model of two parallel capacitors supplemented by the Frumkin adsorption isotherm, the adsorption parameters of Cry by the background of Me4BNF4 were calculated using the regression analysis methods. The calculated dependences of the differential capacitance on the potential adequately agree with experimental curves. The adsorption characteristics of Cry in the studied solutions are compared with those in MgSO4 solutions. By the background of Bu4NBF4, Cry molecules and Bu4N+ cations exhibit very close surface activity and form a mixed adsorption layer. 相似文献
4.
V. P. Korolev O. A. Antonova N. L. Smirnova A. V. Kustov 《Journal of Thermal Analysis and Calorimetry》2011,103(1):347-354
The enthalpies of solution of tetraethyl- and tetra-n-hexylammonium bromides have been measured in mixtures of formamide with ethylene glycol at 298.15 and 313.15 K in the whole mole fraction range by the calorimetric method. The standard enthalpies of solution in binary mixtures have been calculated with Redlich–Rosenfeld–Meyer type equation. The enthalpy and heat capacity parameters of pair interaction of organic electrolytes with EG in FA and with FA in EG have been computed and discussed. The enthalpy interaction parameters of single ions with EG in FA medium have been evaluated and compared with those for ion–water and ion–MeOH interaction in FA. The standard heat capacities of solution have been evaluated. The excess enthalpies of solution, Δsol H E, of Et4NBr, Bu4NBr, and Hex4NBr have been determined. The Δsol H E values are positive for Et4NBr and negative for Bu4NBr and Hex4NBr and become more negative from Bu4NBr to Hex4NBr. 相似文献
5.
The viscosities of solutions of tetrapropylammonium bromide (Pr4NBr), tetrabutylammonium bromide (Bu4NBr), tetrapentylammonium bromide (Pen4NBr), tetrahexylammonium bromide (Hex4NBr), tetraheptylammonium bromide (Hep4NBr), tetraoctylammonium bromide (Oct4NBr), tetrabutylammonium tetraphenylborate (Bu4NBPh4), sodium tetraphenylborate (NaBPh4), and potassium tetraphenylborate (KBPh4) in N,N-dimethylacetamide are reported at 25°C. The viscosity data havebeen analyzed by the Jones-Dole equation for associated electrolytes to evaluate the viscosity B coefficients of the electrolytes. These data have also been analyzed by the transition-state theory to obtain the contribution of the solutes to the free energy of activation for viscous flow of the solution. The ionic contribution to the viscosity B coefficient and the free energy of activation for viscous flow have been estimated using of the reference electrolyte Bu4NBPh4. The bromide, tetraphenylborate, and tetraalkylammonium ions are found to be weakly solvated in N,N-dimethylacetamide, whereas significant solvation has been detected for sodium and potassium ions. The viscosity of the solvent is greatly modified by the presence of all the ions investigated here with the exception of the bromide ion. 相似文献
6.
Shoichi Katsuta Hirokazu Wakabayashi Mariko Tamaru Yoshihiro Kudo Yasuyuki Takeda 《Journal of solution chemistry》2007,36(4):531-547
Equilibria concerning picrates of tetraalkylammonium ions (Me4N+, Et4N+, Pr4N+, Bu4N+, Bu3MeN+) in a dichloromethane−water system have been investigated at 25 ∘C. The 1:1 ion-pair formation constants (K
IP,o
o) in dichloromethane at infinite dilution were conductometrically determined. The distribution constants (K
D
o) of the ion pairs and the free cations between the solvents were determined by a batch-extraction method. The K
IP,o
o value varies in the cation sequence, Bu4N+ ≈ Pr4N+ ≈ Et4N+ < Bu3MeN+ < < Me4N+; this trend is explained by the electrostatic cation−anion interaction taking into account the structures of the ion pairs
determined by density functional theory calculations. For the ion pairs of the symmetric R4N+ cations, there is a linear positive relationship between log10
K
D
o and the number of methylene groups in the cation (N
CH
2). The ion pair of asymmetric Bu3MeN+ has a higher distribution constant than that expected from the above log10
K
D
o
versus
N
CH
2 relationship. These cation dependencies of log10
K
D
o for the ion pairs are explained theoretically by using the Hildebrand-Scatchard equation. For all the cations, the log10
K
D
o value of the free cation increases linearly with N
CH
2; the variation of log10
K
D
o is discussed by decomposing the distribution constant into the Born-type electrostatic contribution and the non-Born one,
and attributed to the latter that is governed by the differences in the molar volumes of the cations. The cation dependencies
of the ion-pair extractability and ion pairing in water are also discussed.
An erratum to this article can be found at 相似文献
7.
The freezing points, conductivities, and densities of NaI, KI, CsI, Bu4NCl, Bu4NBr, Bu4NI, Et4NBr, and Pr4NBr (where Et = ethyl, Pr = propyl, and Bu =n-butyl) in ethylene carbonate have been measured. Osmotic and activity coefficients were calculated from the results. All of the salts studied are strong electrolytes. The trends in the osmotic coefficients of the alkali metal iodides are NaI>KI>CsI, showing that Na+ is more solvated by ethylene carbonate than Cs+. For the tetraalkylammonium halides, the order of osmotic coefficients are Et4NBrPr4NBrBu4NCl>Bu4NBr>Bu4NI. This is the same order as observed in two other high-dielectric-constant solvents, water andN-methylacetamide. The results indicate that the smaller anions are more solvated than the larger anions in ethylene carbonate in contrast to the usual behavior of dipolar aprotic (basic) solvents, such as dimethyl sulfoxide. 相似文献
8.
The resol polycondensation ofC-phenylcalix[4]resorcinarene with formaldehyde affords a corss-linked polymer possessing ion-exchange ability. The ion-exchange
capacity of the polymer with respect to NH4
+, Me4N+, Et4N+, Bu4N+, and K+ cations was determined. The equilibrium in the systemsC-phenylcalix[4]resorcinarene-based polymer—binary or ternary aqueous solutions of electrolytes was studied by potentiometric
titration and quantumchemical MNDO/PM3 calculation
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1475–1477, August, 2000. 相似文献
9.
Rate constants and activation parameters for the isotopic exchange reactions between (PhO)2PSCl and M36Cl (M = Me4N+, Et4N+, n-Bu4N+, Et3HN+, EtH3N+, Li+) in acetonitrile were measured in order to find the effect of the cation nature onthe kinetics of the reaction. The rate constants measured for a range of concentrations of Et3HN36Cl, EtH3N36Cl, and Li36Cl were analyzed using the Acree equation. The equivalent conductance of LiCl in acetonitrile was determined. The nature of the cation has no effect on the mechanism of the reaction. The cation changes only the experimental rate constant proportionally to the dissociation degree of the salt. Smaller values of the rate constant and smaller activation parameters ΔH? and ΔS? for the reaction with Li36Cl indicate the existenceof the intermolecular interaction between lithium ions and O,O-diphenylphosphorochloridothionate. 相似文献
10.
Conductance data are reported for Ph4AsPic, Ph4PPic, Ph4SbPic, Hex4NPic, Bu4PPic, Et4NSbCl6 in propylene carbonate at 25°C in the concentration range 1×10–4 to 15×10–4 M. The data were analyzed by the Justice modification of the Fuoss-Hsia equation and all salts studied were found to be associated and to form solvent separated ion pairs. Application of the Barthel-Bjerrum model of ion association permitted calculation of the non coulombic portion of the potentials of mean force, W±. Ionic limiting equivalent conductances of six ions were calculated using known values of R4N+, and Pic– ions. Walden products of ions in propylene carbonate were examined in the light of modern ion mobility theories, including Boyd-Zwanzig, Hubbard-Onsager, and Hubbard-Kayser models of ion solvent interactions. 相似文献
11.
V. P. Korolev O. A. Antonova N. L. Smirnova A. V. Kustov 《Journal of Thermal Analysis and Calorimetry》2011,103(1):401-407
The enthalpies of solution of tetraethyl- and tetra-n-hexylammonium bromides have been measured in mixtures of formamide with ethylene glycol at 298.15 and 313.15 K in the whole
mole fraction range by the calorimetric method. The standard enthalpies of solution in binary mixtures have been calculated
with Redlich–Rosenfeld–Meyer type equation. The enthalpy and heat capacity parameters of pair interaction of organic electrolytes
with EG in FA and with FA in EG have been computed and discussed. The enthalpy interaction parameters of single ions with
EG in FA medium have been evaluated and compared with those for ion–water and ion–MeOH interaction in FA. The standard heat
capacities of solution have been evaluated. The excess enthalpies of solution, Δsol
H
E, of Et4NBr, Bu4NBr, and Hex4NBr have been determined. The Δsol
H
E values are positive for Et4NBr and negative for Bu4NBr and Hex4NBr and become more negative from Bu4NBr to Hex4NBr. 相似文献
12.
Protonation constants of carbonate were determined in tetramethylammonium chloride (Me4NClaq 0.1 ≤ I/mol kg−1 ≤ 4) and tetraethylammonium iodide (Et4NIaq 0.1 ≤ I/mol kg−1 ≤ 1) by potentiometric ([H+]-glass electrode) measurements. Dependence of protonation constants on ionic strength was taken into account by modified specific ion interaction theory (SIT) and by Pitzer models. Literature data on the protonation of carbonate in NaClaq (0.1 ≤ I/mol kg−1 ≤ 6) were also critically analysed. Both protonation constants of carbonate follow the trend Et4NI > Me4NCl > NaCl. An ion pair formation model designed to take into account the different protonation behaviours of carbonate in different supporting electrolytes was also evaluated. 相似文献
13.
J. Barthel L. Iberl J. Rossmaier H. J. Gores B. Kaukal 《Journal of solution chemistry》1990,19(4):321-337
Conductance data for perchlorates of Li+, K+, Me4N+, Et4N+, Pr4N+, Bu4N+, iodides of K+, Me4N+, i-Am3BuN+, and tetraphenylborates of Na+, Bu4N+ and i-Am3BuN+ in acetonitrile solution in the temperature range −40° to 35°C are reported. Λ° (limiting molar conductance) and KA (association constant) are evaluated for several temperatures using a conductance equation based on the chemical model of
electrolyte solutions including short range forces. Limiting molar ion conductances, λ
ΰ
i
, at −35°, −25°, −15°, −5°, 5°, 15° and 25°C are evaluated from temperature dependent limiting transference numbers. Enthalpies
and entropies of association, obtained from the temperature dependence of the association constants, are also presented.
Dedicated to the memory of Professor Raymond M. Fuoss. 相似文献
14.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1982,38(11):1195-1201
The Raman spectra of six selectively deuterated Me4N+ ions in the methyl stretching regions are reported and the Fermi resonance multiplets caused by interactions with methyl bending overtones are discussed. For the rather simple cases of a single CH3 group in the d9 ion and a single CD3 group in Me4N+-d3 three independent methods for the evaluation of the unperturbed symmetric stretching frequency from the observed Fermi resonance triplet are compared, and the matrix elements W12 and W13, describing this interaction, are determined from the perturbed frequencies and intensities. It is shown that a simple procedure, which determines ν0s from the centre of gravity of an observed Fermi resonance multiplet, can also be applied to more complex cases, e.g. the polarized multiplets of the isotopically pure ions Me4N+ and Me4N+-d12. The origin of the complex Fermi resonance pattern in the latter species is discussed in relation to the increased complexity in the methyl bending region, that has been previously analysed. 相似文献
15.
R. A. Bartlett X. Feng M. M. Olmstead P. P. Power 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):245-248
Abstract The structures of several solvated lithium diorganophosphides are described. These may take a variety of structures including chain-like polymers with alternating Li+ and PR2 ? groups, dimeric species with PR2 ? groups bridging two Li+ ions or mononuclear species having terminal ?PR2 groups which have pyramidal geometries at phosphorus. The Li+ ions in all structures are solvated by either THF or Et2O bases. Separation of the Li+ can be effected using 12-crown-4 to coordinate Li+ as [Li(12-crown-4)2]+ affording free [PR2]? counterions. An extension of these techniques has led to the synthesis of the first compounds which have B-P double bonds. These are the compounds [Li(Et2O)2PRBMes2] and [Li(12-crown-4)2][PRBMes2](R=Ph, C6H11,Mes) which have B-P bond lengths of 1.82 – 1.83Å. 相似文献
16.
The effect of the supporting electrolytes tetraethylammonium p-toluenesulfonate, methanesulfonate and trifluoromethanesulfonate on the polarographic reduction of alkali metal ions in N,N-dimethylformamide and acetonitrile has been investigated. In tetraethylammonium trifluoromethanesulfonate supporting electrolyte, the polarographic reductions of alkali metal ions are almost the same as those in perchlorate in both solvents. In tetraethylammonium p-toluenesulfonate and methanesulfonate, the half-wave potentials shift to more negative potentials, especially in acetonitrile. These shifts can be explained in terms of ion-pair formation between the alkali metal ion and the supporting electrolyte anion. 相似文献
17.
A possibility of obtaining fluorine-containing N-phenylphenylglycine derivatives at yields of up to 85% via the electrochemical carboxylation of corresponding benzalanilines was shown. The influence of imine's electron structure, the nature of supporting electrolyte and cathodic material on such processes is examined. It was found, that increasing electron accepting ability of the substituents in benzylidene and aniline fragments of the imine molecule lead to decrease of amino acid yields. The dependence of the N-phenyl-p-fluorophenylglycine yield on the cathode material (Zn, GC, Cu, Ag, Pt) and on the nature of the supporting electrolytes (Bu4NBr, Et4NBr, Et4NClO4, PhCH2Me3NClO4, LiBF4, LiClO4, NaBF4 and KBF4) was investigated. The highest amino acid yields were obtained at cathodes (GC and Zn) that do not exhibit specific adsorption of fluorine-containing imines, as well as in the presence of background salts (Alk4NBr) whose cations do not show tendency to strong ion pairing with anion radicals formed by the electrochemical activation of the imines. 相似文献
18.
A. Sobkowska 《Journal of Radioanalytical and Nuclear Chemistry》1983,78(1):43-51
The results of a study on the polarographic behaviour of TBP and its influence on the determination of uranyl ions is presented. The half-wave potential of the adsorption wave of TBP depends on the concentration of TBP, type of supporting elec trolyte and its concentration. In the presence of TBP the polarographic wave of U(VI) ion is changed. Below 7·10?5 M TBP the polarographic wave of U(VI) is not affected, between 7·10?5 and 2·10?4 M TBP the shape, height and half-wave potential of U(VI) waves are changed and above 2·10?4 M, up to saturated solution of TBP, the waves of U(VI) do, not change further. The bes supporting electrolytes for the determination of U(VI) are KNO3 or NaClO4 in concentrations of 0.1 to 0.5 M, pH 1–2 and TBP concentrations from 3·10?4 to 1.2·10?3 M. 相似文献
19.
Perraud O Robert V Martinez A Dutasta JP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(15):4177-4182
The heteroditopic hemicryptophane 1 , which bears a tripodal anion binding site and a cation recognition site in the molecular cavity, proved to be an efficient ion‐pair receptor. The hemicryptophane host binds anions selectively depending on shape and hydrogen‐bond‐accepting ability. It forms an inclusion complex with the Me4N+ ion, which can simultaneously bind anionic species to provide anion@[ 1? Me4N+] complexes. The increased affinity of [ 1? Me4N+] for anionic species is attributed to a strong cooperative effect that arises from the properly positioned binding sites in the hemicryptophane cavity, thus allowing the formation of the contact ion pair. Density functional theory calculations were performed to analyze the Coulomb interactions of the ion pairs, which compete with the ion‐dipole ones, that originate in the ion–hemicryptophane contacts. 相似文献
20.
Yizhak Marcus 《Journal of solution chemistry》2008,37(8):1071-1098
Property data for tetraalkylammonium cations, [H(CH2)
n
]4N+, are reviewed. They pertain to the isolated cations and their transfer from the gas phase into aqueous solutions. Various
properties of these cations in aqueous and non-aqueous solutions and data for their transfer between these are also reviewed.
Emphasis is placed on the dependence of data on the length n of the alkyl chains rather than on the absolute values. Most of the data are available only for the first four members of
the series.
The properties of the isolated ions increase linearly with the chain length. Molar enthalpies of formation of the gaseous
and aqueous cations, and absolute standard molar enthalpies of hydration, are derived. Standard molar entropies of dissolution
of several salts in water are obtained from their solubilities and enthalpies of solution. The molar entropies of the crystalline
iodides of the first four members of the series then give the standard partial molar entropies of the aqueous cations and
their molar entropies of hydration.
The standard partial molar volumes in aqueous and non-aqueous solutions are quite linear with n and in non-aqueous solutions the molar volume hardly depends on the nature of the solvent. On transfer from water to non-aqueous
solvents the volume of Me4N+ suffers some shrinkage, that of Et4N+ appears to be unaffected, but from Pr4N+ onwards an increasing expansion takes place. This unexpected result is tentatively explained by hydrophobic intra-molecular
association of pairs of alkyl chains in aqueous solutions, resulting in a tightening of the structure. The transfer of the
R4N+ cations from water into non-aqueous solvents is governed by a large positive entropy change, outweighing the smaller positive
enthalpy change.
The transport properties of the aqueous R4N+ cations are non-linear with n. A major impediment to movement is thus the sticking of the water molecules to the ice-like hydrophobic hydration sheaths
of the larger cations. The number of water molecules affected by the hydrophobic cations is open to widely differing estimates
resulting from various approaches, and constitute an open issue. 相似文献