Contribution to the thermodynamics of complexes of alkali metal cations with dibenzo-18-crown-6 in water-nitrobenzene extraction system

1984 ◽  
Vol 49 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Emanuel Makrlík ◽  
Jaroslava Hálová ◽  
Miroslav Kyrš
Keyword(s):  
Alkali Metal ◽  
Alkali Metal Cation ◽  
Alkali Metal Cations ◽  
Complex Species ◽  
Cation Order ◽  
Extraction Constants ◽  
Equilibrium Data ◽  
Individual Extraction Constants ◽  
The Stability ◽  
The Individual

The stability constants for the ML+ complex species, where M+ is an alkali metal cation and L is dibenzo-18-crown-6, in nitrobenzene saturated with water were calculated by employing published equilibrium data. The stability is found to increase in the cation order Li+ < Cs+ < Rb+ < K+ < Na+. For the NaL+, KL+, RbL+, and CsL+ complex cations the individual extraction constants in the water-nitrobenzene system were determined; their values increase in the series Na+ < K+ < Rb+ < Cs+.

scholarly journals Complexation of some univalent organic cations with benzo-18-crown-6 in nitrobenzene saturated with water

2012 ◽  
Vol 10 (5) ◽  
pp. 1495-1499
Author(s):  
Emanuel Makrlík ◽  
Petr Vaňura ◽  
Pavel Selucký
Keyword(s):  
Cationic Complex ◽  
Two Phase ◽  
Complex Species ◽  
Nitrobenzene Phase ◽  
Cation Order ◽  
Activity Measurements ◽  
Extraction Constants ◽  
Univalent Organic Cations ◽  
Phase Water ◽  
The Stability

AbstractFrom extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium C+(aq) + 1·Na+(nb) 1·C+ (nb) + Na+(aq) taking place in the two-phase water-nitrobenzene system (C+ = methylammonium, ethylammonium, propylammonium, ethanolammonium, diethanolammonium, triethanolammonium, cation TRIS+, hydrazinium, hydroxylammonium; 1 = benzo-18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the 1·C+ cationic complex species in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: triethanolammonium +

The extraction of alkali metal picrates by polyurethane foam using crown ether

1981 ◽  
Vol 59 (10) ◽  
pp. 1490-1496 ◽  
Author(s):  
Anjum S. Khan ◽  
W. G. Baldwin ◽  
A. Chow
Keyword(s):  
Crown Ether ◽  
Alkali Metal ◽  
Polyurethane Foam ◽  
Dissociation Constants ◽  
Extraction Constant ◽  
Ion Pair ◽  
Constant Sequence ◽  
Extraction Constants ◽  
The Stability ◽  
Ether Complex

The distribution of alkali metal picrates between water and polyurethane foam was studied in the presence of dicyclohexyl 18-crown-6 (DCHC-6). The extraction constants and dissociation constants for the ion pair (MCrA) in polyurethane foam were determined. The extraction constant sequence of the alkali metal ions with DCHC-6 is K+ > Rb+ > Cs+ > Na+ and mainly depends on the stability of the alkali metal – crown ether complex.

Active surface centres in vanadium pentoxide/alkali metal sulphate heterogeneous catalysts for 2-propanol decomposition

1979 ◽  
Vol 57 (18) ◽  
pp. 2464-2469 ◽  
Author(s):  
David Victor Fikis ◽  
William John Murphy ◽  
Robert Anderson Ross
Keyword(s):  
Alkali Metal ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
Heterogeneous Catalysts ◽  
Catalyst Activity ◽  
Active Surface ◽  
Hydroxyl Groups ◽  
Kinetic Measurements ◽  
The Stability ◽  
The Individual

Infrared spectra of the surfaces of vanadium pentoxide and vanadium pentoxide containing 9.09 mol% caesium and potassium, as sulphates, have been determined after exposure to 2-propanol for various times. Interpretation of the spectra leads to the proposal that the principal source of catalyst activity may be associated with surface hydrogen and hydroxyl groups on V5+ and V4+ sites. The "stability" of the catalysts towards reduction by the alcohol was consistent with the activity series derived from kinetic measurements: V2O5 (pure) < V2O5 (Cs) < V2O5 (K). The degree of sample reduction has also been assessed qualitatively by measurements of the ratio of surface area before to that after reaction and the same catalyst sequence was established. The trend in surface area ratios was similar to that shown by the surface "Tammann" temperatures of vanadium pentoxide and alkali metal sulphates which has been taken to imply that the ease and (or) extent with which the sulphates enter into inter-solid reactions with the oxide in the preparation stage may exert influence on the subsequent reducibility of the individual members of the catalyst series.

Tetrapyrrolic compounds as hosts for binding of halides and alkali metal cations

2009 ◽  
Vol 13 (11) ◽  
pp. 1148-1158 ◽  
Author(s):  
Mikalai M. Kruk ◽  
Aleksander S. Starukhin ◽  
Nugzar Zh. Mamardashvili ◽  
Galina M. Mamardashvili ◽  
Yulia B. Ivanova ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Pyridine Ring ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Cation Binding ◽  
Halide Ions ◽  
Alkali Metal Cations ◽  
Cation Complexation ◽  
Iodide Ions ◽  
Binding Isotherms

In this paper the binding of halides and alkali metal cations with porphyrin hosts is reported. The halide ions are complexed with diprotonated porphyrin macrocycle with high affinity and stable complexes of 1:1 and 1:2 structures with halide ions are formed. Strong (up to 300 times) quenching of the porphyrin fluorescence has been found upon the titration of porphyrin solutions with iodide ions. It was established that both static quenching upon formation of the non-fluorescent complex and dynamic diffusion-controlled quenching took place. It is shown that the halide ions binding isotherms can be linearized with double-logarithmic plots. The alkali metal cations are trapped with mono-meso-arylporphyrins containing a conformationally mobile complexing polyether fragment on the benzene ring with a terminal pyridine ring. The alkali metal cation binding constant depends on the polyether chain length. The five-membered (n = 5) polyether chain provides very high binding selectivity for potassium over lithium or sodium. The potassium complexation constants 3.6 × 105 and 7.2 × 104 M-1 have been obtained for Zn 2+ complex and diprotonated porphyrin, respectively. For signaling of the alkali cation complexation, it is proposed to use the binding between the terminal pyridine ring with either the Lewis acidic site (chelated Zn 2+ ion) or the diprotonated macrocycle core ( H 4 P 2+) acting as salt bridging site.

scholarly journals Bonding in Group 1 Citrate Salts

2014 ◽  
Vol 70 (a1) ◽  
pp. C655-C655
Author(s):  
James Kaduk ◽  
Alagappa Rammohan
Keyword(s):  
Hydrogen Bonds ◽  
Alkali Metal ◽  
Weak Interactions ◽  
Alkali Metal Cation ◽  
Quantitative Measure ◽  
Electrostatic Energy ◽  
Hydroxyl Groups ◽  
Local Environments ◽  
The Stability ◽  
Cation Size

Computational studies of > 15 new crystal structures and the 10 previously-reported structures of alkali metal citrates provide insight into why the atoms are where they are. The metal-citrate bonding is predominantly ionic, with very little covalent character, which decreases as the cation size increases. Bond valence calculations indicate that most cations are crowded, and that the crowding decreases as the cation size increases. Although most oxygen atoms coordinate to the metals, a few do not, and they tend to be the least-negative oxygens. Both the citrate hydroxyl groups and water molecules tend to bridge two cations, and the carboxylate coordination is more varied. The solid state energy differences are dominated by differences in van der Waals and electrostatic energy contributions. In the Li and Na salts, the citrate anion occurs predominantly in a higher-energy "kinked" conformation, rather than the extended lowest-energy conformation observed in salts of the larger cations. Detailed conformational analysis of the citrate anions enables quantification of the conformational energy costs in these solids. Hydrogen bonding is important to the stability of these salts. The Mulliken overlap population in the hydrogen bonds provides a quantitative measure of their strength, and permits identification of long (weak) interactions which are significant in some of these compounds. Patterns in both the local environments of the hydrogen bonds and the more-extended features (graph sets) are noted. Polymorphs and sets of isostructural compounds permit more-detailed analysis of the structures and energetics in these compounds. The order of ionization of the three carboxylic acid groups is in general central/terminal/terminal, but there are two exceptions. While we have concentrated on salts containing a single alkali metal cation (and hydrogen), the structures of NaK2C6H5O7 and NaKHC6H5O7 provide an exciting window on a larger universe of mixed salts.

Trends in field desorption mass spectra of several series of alkali metal cryptates: thermodynamic rationale and analytical implications

1980 ◽  
Vol 58 (7) ◽  
pp. 681-685 ◽  
Author(s):  
Gordon Walter Wood ◽  
Mei-Kuen Au ◽  
Ning Mak ◽  
Pui-Yan Lau
Keyword(s):  
Alkali Metal ◽  
Thermodynamic Parameters ◽  
Mass Spectra ◽  
Goodness Of Fit ◽  
Metal Cations ◽  
Complex Stability ◽  
Field Desorption ◽  
Alkali Metal Cations ◽  
The Stability ◽  
Almost All

Field desorption mass spectra have been recorded for most of the 45 cryptates which may be formed from complexation of [2.2.2]-, [2.2.1]-, and [2.1.1]-cryptand with Li+, Na+, an d K+ ions in combination with the anions Cl−, Br−, I−, OTs−, and BPh4−. The cryptate cation predominated in almost all of the spectra. The stability of the complexes was found not to be simply related to goodness of fit of the cation in the cryptand cavity, but a significant trend in stability in the order BPh4 > 1 > Br > Cl was found. This order of complex stability was shown to be consistent with known thermodynamic parameters. These results are discussed briefly in terms of applications to analysis of alkali metal cations.

scholarly journals The effect of the alkali metal cation on the electrocatalytic oxidation of formate on platinum

RSC Advances ◽  
2014 ◽  
Vol 4 (29) ◽  
pp. 15271-15275 ◽  
Author(s):  
Bruno A. F. Previdello ◽  
Eduardo G. Machado ◽  
Hamilton Varela
Keyword(s):  
Alkali Metal ◽  
Metal Cation ◽  
Electrocatalytic Oxidation ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Alkali Metal Cations ◽  
Non Covalent Interactions ◽  
Electro Oxidation ◽  
Covalent Interactions

Non-covalent interactions between hydrated alkali metal cations and oxygenated species on platinum considerably impact the mechanism of formate electro-oxidation.

scholarly journals Solvent extraction of Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Co2+ and Ni2+ into nitrobenzene using strontium dicarbollylcobaltate and tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate

2008 ◽  
Vol 73 (12) ◽  
pp. 1181-1186 ◽  
Author(s):  
E. Makrlík ◽  
J. Budka ◽  
P. Vaňura ◽  
P. Selucký
Keyword(s):  
Two Phase ◽  
Nitrobenzene Phase ◽  
Tert Butyl ◽  
Cation Order ◽  
Activity Measurements ◽  
Extraction Constants ◽  
Exchange Extraction ◽  
Phase Water ◽  
The Stability ◽  
Water Saturated

The exchange extraction constants corresponding to the general equilibrium M2+(aq) + SrL2+(nb) ? ?ML2+(nb) + Sr2+(aq) occurring in the two- -phase water-nitrobenzene system (M2+ = Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+ , Mn2+, Co2+ or Ni2+; L = tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate; aq = aqueous phase; nb = nitrobenzene phase) were evaluated from extraction experiments and ?-activity measurements. Furthermore, the stability constants of the ML2+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Ba2+ < Mn2+ < Pb2+, Co2+ < Cu2+, Zn2+ < Cd2+, Ni2+ < UO22+ < Ca2+.

Crystal Structures of Titanium(III) Bis(acetylide) Tweezer Complexes with Alkali Metal Cations

1997 ◽  
Vol 62 (9) ◽  
pp. 1446-1456 ◽  
Author(s):  
Jörg Hiller ◽  
Vojtech Varga ◽  
Ulf Thewalt ◽  
Karel Mach
Keyword(s):  
Alkali Metal ◽  
Crystal Structures ◽  
Metal Cation ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Polymer Chains ◽  
Alkali Metal Cations ◽  
Bonding Interaction ◽  
Intermolecular Bonding ◽  
Trimethylsilyl Groups

Crystal structures of the Ti(III) tweezer complexes [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-[Li(THF)2]+ (2a), [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-Na+ (3) and [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-Cs+ (5) have been determined. In all of them the alkali metal cation is placed away from the Ti-Cα1-Cα2 plane at the distance: Li+ 0.511 Å, Na+ 1.023 Å and Cs+ 0.521 Å. The reason for the deviation of Li+ in 2a is the asymmetrical orientation of the THF ligands in the [Li(THF)2]+ cation with respect to the Ti-Cα1-Cα2 plane, which seems to release the steric congestion between the THF ligands and the trimethylsilyl groups. In 3 and 5, the molecules form polymer chains with a weak intermolecular bonding interaction between the cations and one of the C5HMe4 ligands of the neighbouring molecule in a sandwich manner.

Sign in / Sign up

Export Citation Format

Share Document