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

From 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 +

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

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+.

Stability of the barium-benzo-15-crown-5 complex in nitrobenzene saturated with water

From extraction experiments and ?-activity measurements, the exchange extraction constant corresponding to the equilibrium Ba2+(aq) + SrL2 2+(nb) _ BaL 2 2+(nb) + Sr2+(aq) occurring in the two-phase water-nitrobenzene system (L = benzo-15-crown-5; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K ex (Ba2+, SrL22+) = 0.3 ? 0.1. Furthermore, the stability constant of the benzo-15-crown-5-barium complex in nitrobenzene saturated with water was calculated for the temperature of 25 ?C: log ?nb (BaL2 2+) = 13.3?0.1.

Extraction of calcium from water into nitrobenzene using strontium dicarbollylcobaltate in the presence of 18-crown-6

From extraction experiments and g-activity measurements, the extraction constant corresponding to the equilibrium Ca 2+ (aq)+ SrL 2+ (nb) === CaL 2+ (nb) + Sr 2+ (aq) taking place in the two-phase water-nitrobenzene system(L= 18-crown-6, aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex(Ca 2+, SrL 2+) = -1.9 ?0.1. Furthermore, the stability constant of the calcium - 18-crown-6 complex in nitrobenzene saturated with water was calculated for the temperature of 25?C: log bnb (CaL 2+)=10.1?0.1.

Extraction of 133Ba with Bis[undecahydro-7,8-dicarbaundecaborato(2-)]cobaltate(1-) in the Presence of Dibenzo-18-crown-6

Extraction of barium with the nitrobenzene solution of bis[undecahydro-7,8-dicarbaundecaborato(2-)]cobaltate(1-) in the presence of dibenzo-18-crown-6 (DB18C6, L) has been investigated. The equilibrium data and typical maxima in the dependences of the Ba distribution ratios on the analytical concentration of DB18C6 in the system can be explained assuming that the species Ba2+, BaL2+, BaL22+, BaHL3+ and BaHL23+ to be extracted into the nitrobenzene phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.

The Extraction Transfer of H+-18-Crown-6 Species across the Water-Nitrobenzene Phase Boundary in the Extraction of Aqueous Solutions of Perchloric Acid by Nitrobenzene in the Presence of 18-Crown-6

A study was made of the extraction of perchloric acid in water-nitrobenzene-18-crown-6 (hereafter L) systems. The experimental data was interpreted on the basis of the assumption that the extraction occurs according the equations H+aq + ClO4,aq- ↔ H+org + ClO4,org- and H+aq + Laq + ClO4,aq- ↔ HL+org + ClO4,org-. Crown is also protonated in the aqueous phase according to the equation H+aq + Laq ↔ HL+aq. The values of the corresponding extraction constants, the protonation constants of 18-crown-6 in nitrobenzene and water and the individual extraction constants of the HL+ species in the water-nitrobenzene system were determined, along with the magnitude of the molar free enthalpy for the transfer of these species across the given phase boundary.

Extraction of Alkali Metal and Ammonium Dipicrylaminates into Nitrobenzene in the Presence of Some Acyclic Polyethers

The effect of the presence of six different acyclic polyethers (2-glym, 3-glym, 4-glym, PEG 200, PEG 300 and PEG 400), denoted by L, on the distribution of alkali metal dipicrylaminates and ammonium dipicrylaminate (MA) between the aqueous and nitrobenzene phases has been studied. The two-phase system can be quantitatively described by the following five chemical equilibria: Ma+ + Aa- + L0 ↔ MLa+ + Aa-,Ma+ + Aa- ↔ M0+ + A0-, MLA0 ↔ ML0+ + A0-, MA0 ↔ M0+ + A0-, La ↔ L0, for which the respective equilibrium constants Kex(ML+, A-), Kex(M+, A-), Kd0(MLA), Kd0(MA) and KD were determined. The values of Kex(ML+,A-) increase with the increasing crystallographic radius of the M+ ion and with the number of oxyethylene units in the molecule of the ligand, L, in the series 2-glym < 3-glym < 4-glym < PEG 200 < PEG 300 < PEG 400. In addition, it has been demonstrated that the stability of the ML0+ species in the nitrobenzene phase has a maximum value for M+ = Na+ for all the studied ligands. The presence of the polyethers is detrimental to the separation of Cs+ from the other cations, but improves the separation of Na+ from Li+. The extraction selectivities for the K+/NH4+, K+/Li+ and NH4+/Li+ pairs was not significantly affected by the presence of the ligands, except for 2-glym.

Ionic product of water in the nitrobenzene phase of the two-phase water-nitrobenzene extraction system

General relations among thermodynamic parameters, which characterize the transfer of the ions H+ and OH- from the aqueous into nitrobenzene phase of the two-phase water-nitrobenzene extraction system and dissociation equilibria of H2O in both phases of this system, have been derived. Further, using the known parameters ionic product of water in nitrobenzene saturated with water has been evaluated for a temperature of 25°C: PnbH2O = 10-29.2 mol2 dm-6.

Contribution to the thermodynamics of bromophenol blue in the two-phase water-nitrobenzene extraction system

General relations among thermodynamic parameters characterizing dissociation equilibria with species H2A, HA- and A2- (H2A is a symbol for an electroneutral undissociated acid) in a two-phase extraction system have been derived. From the extraction measurements, the equilibrium distribution constant of electroneutral bromophenol blue between the nitrobenzene phase and the aqueous one has been determined: log KD(H2A) = 3.60 ± 0.01. By using this value and further known constants and applying the mentioned relations the following values of dissociation constants of bromophenol blue in nitrobenzene saturated with water have been calculated for a temperature of 25 °C: pKaorg(H2A) = -log Kaorg(H2A) = 10.1 and pKaorg(HA-) = -log Kaorg(HA-) = 14.5.