膦酸根型水溶性膦配体的质子离解和紫外光谱特性

随着两相催化研究的深入 ,各种水溶性配体 ,特别是水溶性膦配体的种类和合成方法日益多样化[1 ] ,含磷酸根的膦配体是其中一类重要的水溶性膦配体[2 ,3] ,微溶于水 ,其膦酸钠、钾盐具有良好的水溶性 ,因此膦酸根中质子离解对配体和金属配合物的存在形式[4,5] 、水溶性和金属配合物的回收使用都会有较大的影响。我们曾报道以乙烯利为起始原料合成氨乙基膦酸及其衍生物的简便方法[6] ,并利用Ｍａｎｎｉｃｈ型反应引入二苯基膦甲基配位络合基团 ,制备其相应的水溶性钠盐[7] 。本文报道二苯基膦甲基、醚键和羟基的引入对上述水溶性配体中膦酸根…     

Chromatographic and potentiometric determination of dissociation constants of weakly basic Aroma compounds

Summary Reversed-phase liquid chromatography on two stationary phases—octadecylbonded silica Partisil ODS-3 and polystyrene-divinylbenzene resin PRP-1—and potentiometric titration in the water/methanol mobile phase were investigated in order to determine the dissociation constants of three weakly basic aroma compounds, namely trimethyl pyrazine, 2,4-dimethyl thiazole and methyl anthranilate. The data obtained from both methods are quite consistent and compare favourably to values found in the literature.     

Determination of dissociation constants for some pyrogallol azo derivatives and stability constants of their complexes with rare-earth metals

The dissociation constants of some haloazo derivatives of pyrogallol and the stability constants of their complexes with rare-earth metals (La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) are determined by potentiometric titration in aqueous ethanol (3: 7). A correlation between the dissociation constants of the reagents and the stability constants of their complexes is found.     

Correlation between the rates of benzylidene condensation of R-tetrazol-1-ylphenylamines and their dissociation constants

Benzylidene condensation of R-tetrazol-1-ylphenylamines with 4-fluorobenzaldehyde was studied. The correlation between the logarithm of the rate constant of the condensation of 4-fluorobenzaldehyde with R-tetrazol-1-ylphenylamines and their pK _BH+ values was found. The reaction constant ρ in the Hammett equation was determined.     

Structure of the CCl3CCl=NCH2C6H5 molecule and reorientations of its CCl3 group, according to ab initio calculations

The optimal geometry of the isolated CCl₃CCl=NCH₂C₆H₅ molecule and the intramolecular barrier to reorientations of its trichloromethyl group are calculated by the RHF/6-31G* and B3LYP/6-31G* methods. The barrier found (14.1 kJ mol^?1) is compared to that determined previously by ³⁵Cl NQR for a crystal of this compound, which allows estimation of the contribution of intermolecular interactions to braking of this motion of the CCl₃ group. The structural features of the molecule of this compound are consistently manifested in quantum-chemical calculations and NQR spectra.     

Potentiometric determination of the dissociation constants of an asymmetric sorbent containing l-proline, and the stability constants of its Cu(II) complexes

The dissociation constants of the carboxyl groups (pK(a1) = 2.2, n = 1.8) and amino groups (pK(a2) = 9.5, n(2) = 1.6) of a sorbent prepared by reacting l-proline with a cross-linked chloromethylated styrene polymer have been determined by potentiometric titration. The potentiometrically measured stability constants of the Cu(II) complexes of the resin (logbeta(1) = 6.9 and log beta(2) = 12.4) were found to be close to the values for the Cu(II) complexes of N-benzyl-l-proline. For complexed resins of alpha-amino-acid type the pH-values of decomplexation do not appear to be directly correlated with the stability constants.     

Ion exchangers containing phosphorus in their functional group

Summary Uranium or thorium separations from a number of various ions were studied by means of cation exchangers containing phosphorus in their functional group. These ion exchangers adsorb selectively only UO₂ ²⁺ or Th⁴⁺ ions from the mixture studied in a medium of >0.4 N nitric or hydrochloric acid. Several di- and trivalent cations are not sorbed under these conditions. In the absence of UO₂ ²⁺ and Th⁴⁺ ions, Me²⁺ may be more easily separated quantitatively from Me³⁺ in 0.2 N nitric or hydrochloric acid than with cation exchangers containing the -SO₃H group.

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Zusammenfassung Die quantitative Trennung von UO₂ ²⁺ oder Th⁴⁺ von einer Reihe anderer Ionen wurde mit Hilfe phosphorhaltiger Kationenaustauscher untersucht. Diese Ionenaustauscher sorbieren selektiv nur UO₂ ²⁺ oder Th⁴⁺-Ionen aus einem Medium von >0,4 N HNO₃ oder HCl. Eine Reihe verschiedener zwei- und dreiwertiger Kationen wird unter diesen Bedingungen nicht sortiert. Bei Abwesenheit von UO₂ ²⁺- und Th⁴⁺-Ionen kann man Me²⁺ in 0,2 N HNO₃- oder HCl-Lösung quantitativ von Me³⁺ trennen, und zwar leichter als mit -SO₃H-haltigen Austauschern.