The Extraction of Anionic Beryllium Complexes by Tri-iso-octylamine

1962 ◽  
Vol 15 (3) ◽  
pp. 457 ◽  
Author(s):  
HJ de Bruin ◽  
D Kairaitis ◽  
RB Temple
Keyword(s):  
Aqueous Solution ◽  
Stability Constants ◽  
Complexing Agents ◽  
Conditional Stability ◽  
Tertiary Amines ◽  
Ph Titration ◽  
Anionic Complexes ◽  
The Stability ◽  
Conditional Stability Constants ◽  
Beryllium Complexes

The extraction of beryllium from aqueous solution by long-chain tertiary amines has been observed in the presence of ligands giving rise to anionic complexes. The nature of the oxalate complex extracted by solutions of tri-iso-octylamine in chloroform has been studied in detail and the species formed in the organic phase were shown to have the composition Be(C2O4)2.{NH(i-C8H15)3}2. The complexes formed in aqueous solution between beryllium and several anionic complexing agents have been examined by the method of pH-titration. Conditional stability constants have been obtained for the complexes formed with oxalic, malonic, maleic, succinic, phthalic, and salicylic acids. Differences in their extractabilities can be explained semiquantitatively with the help of the stability constants and the acid association constants of the complexing agents.

Copper complexation by isatin β-thiosemicarbazones in aqueous solution

1981 ◽  
Vol 34 (12) ◽  
pp. 2549 ◽  
Author(s):  
H Stunzi
Keyword(s):  
Aqueous Solution ◽  
Stability Constants ◽  
Antiviral Drug ◽  
Copper Electrode ◽  
Water Soluble ◽  
Conditional Stability ◽  
Cupric Ion ◽  
Copper Complexation ◽  
The Stability

The reactions in aqueous solution between cupric ion and water-soluble derivatives of the antiviral drug methisazone (1-methylisatin β-thiosemicarbazone, mibt) have been investigated. Alkalimetric titrations and n.m.r. experiments showed that 5-sulfonatoisatin β-thiosemicarbazone, sibt (3), its 1-methyl derivative, msibt (4), and also p-sulfonatobenzaldehyde thiosemicarbazone, sbat (5), reduce cupric ion and form copper(I) complexes. Stability constants were obtained from measurements of pH and pCu+ on solutions of copper(II) nitrate and excess ligand (I = 0.15 M KNO3, at 37�). The pCu+ values were obtained with an ORION solid state copper electrode. At pH 6-7.5 and moderate excess of ligand, polymeric complexes with an approximate 1 : 1 copper(1)-to-ligand ratio are formed: CunLn or CunLn+,H with n > 6. Monomeric complexes CuL23- predominate at higher pH and in the presence of a more than twentyfold excess of ligand. The stability constants log β2 are 17.9 for sibt, 18.5 for msibt and 19.8 for sbat. At physiological pH (7.4), the order of stability is msibt > sibt & sbat, with conditional stability constants log β2 = 16.2, 15.7 and 13.4, respectively. Comparison with penicillamine shows that some in vivo complexation of copper(I) by methisazone may be possible. On the other hand, a histidinato-copper(II) complex is formed in the presence of histidine.

Can chelation be important in the antiviral activity of isatin β-thiosemicarbazones?

1982 ◽  
Vol 35 (6) ◽  
pp. 1145 ◽  
Author(s):  
H Stunzi
Keyword(s):  
Stability Constants ◽  
Metal Ion ◽  
Copper Ions ◽  
Conditional Stability ◽  
Biologically Relevant ◽  
Cupric Ion ◽  
The Stability ◽  
Conditional Stability Constants ◽  
Metal Ion Chelation

The stability constants of 5-sulfonatoisatin β-thiosemicarbazone (β-thiosemicarbazonoisatin-5- sulfonate) [sibt,(3)] with Zn2+ and Fe2+ have been determined from slow pH titrations (I 0.15M KNO3, 37�). At pH 7.4, the conditional stability constants for the sibt complexes are logK1' 4.5 (Zn2+), 3.1 (Fe2+) and log β2' 8.9 (Zn2+), 6.5 (Fe2+). The mixed ligand complexes Zn(sibt)L (L = histidine or glycine) have conditional stability constants log β1110' 8.8 and 7.0, respectively, at pH 7.4. Copper(I) complexes of sibt and bishistidinato-copper(II) coexist in mixtures of Cu2+, sibt and histidine. [In solutions of copper ions, sibt (complexes Cu+) and histidine (chelates Cu2+), the response of the Orion cupric-ion-selective electrode is not stoichiometric.] Also studied was 1-methyl-5-sulfonatoisatin β-thiosemicarbazone [msibt,(4)] which behaves like sibt. 5-Sulfonatoisatin β-semicarbazone and p-sulfonatobenzaldehyde thiosemicarbazone (p-thiosemicarbazonomethyl- benzenesulfonate) are weak ligands. Comparison of the stability constants with those of complexes of biologically relevant chelating agents showed that isatin β-thiosemicarbazones are not expected to form stable complexes with zinc and iron in vivo. Bidentate thiosemicarbazones, such as benzaldehyde thiosemicarbazones, form even weaker complexes. Both classes of thiosernicarbazones have a similar activity against vaccinia virus; this activity seems not to depend on metal ion chelation.

Fluorescence Analysis of Cu(II), Pb(II) and Hg(II) Ion Binding to Humic and Fulvic Acids

2016 ◽  
Vol 851 ◽  
pp. 135-140 ◽  
Author(s):  
Vojtěch Enev ◽  
Irena Türkeová ◽  
Jana Szewieczková ◽  
Leos Doskocil ◽  
Martina Klučáková
Keyword(s):  
Humic Substances ◽  
Stability Constants ◽  
Metal Ion ◽  
Fluorescence Analysis ◽  
Fulvic Acids ◽  
Ion Binding ◽  
Conditional Stability ◽  
Metal Ion Binding ◽  
The Stability ◽  
Conditional Stability Constants

Abstract. The aim of this work was to study molecular and quantitative aspects of metal ion binding to humic substances (HS). The object of our study was characterization of two standards of humic substances (Elliott Soil standard HA 1S102H and Elliott Soil standard FA 2S102F). All samples of IHSS standards HS were characterized by elemental analysis (EA), ultraviolet-visible spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR) and steady-state fluorescence spectroscopy. Chemical parameters on the complexation of Cu (II), Pb(II) and Hg(II), including the conditional stability constants and the percentage of fluorophores participating in the complexation, were estimated by the modified Stern–Volmer equation. The stability constants (log Ka) of Me(II)–ESHS complexes range from 3.70 to 5.15 in the order: Hg–ESHA>Cu–ESHA>Pb–ESHA>Cu–ESFA>Pb–ESFA. With respect to the ESHA, ESFA, which showed the smallest contents of O-containing functional groups (e.g. hydroxyl, carbonyl, ester, especially carboxyl groups on the aromatic ring) and the lowest humification degree, the ESFA was characterized by much smaller stability constants. Our findings suggest that soil HS belongs to class of important organic ligands for complexation with heavy metal ions and may significantly affect the chemical forms, mobility, bioavailability and ecotoxicity of heavy metals in the soil environment.

scholarly journals Complexometric determination: Part I - EDTA and complex formation with the Cu2+ ion

2002 ◽  
Vol 56 (7-8) ◽  
pp. 338-345 ◽  
Author(s):  
Milos Rajkovic
Keyword(s):  
Complex Formation ◽  
Metal Ions ◽  
Stability Constants ◽  
Main Reaction ◽  
Complexing Agents ◽  
Wide Field ◽  
Conditional Stability ◽  
Edta Complex ◽  
Equilibrium Reactions ◽  
Conditional Stability Constants

Compounds forming very stable complexes - chelates, have a wide field of application in analytical chemistry. The most famous group of these compounds are complexons. Complexons represent organic polyaminocarbonic acids as for example ethylenediaminetetraacetic acid (EDTA) and its salts. The EDTA molecule has six coordinative sites. It is a hexadentate ligands i.e. it has two binding nitrogen atoms and four oxygen atoms from carboxyl groups and it forms complexes with almost all metal ions. EDTA as a tetraprotonic acid, H4Y disociates through four steps, yielding the ions HsY-, H2Y2-, HY3- and Y4-. Which of the EDTA forms will be encountered in a solution, depends on the pH. Due to the poor solubility of EDTA in pure water, as well as in most organic solvents, the disodium salt of EDTA Na2H2Y-2H2O, under the commercial name complexon III, is utilized for analytical determinations. In water, EDTA forms soluble, stabile chelate complexes with all cations, at the molar ratio 1:1, regardless of the charge of the metal ion. In contrast to other equilibria, which are mainly defined by Le Chatellier's principle, equilibria related to metal-EDTA complex formation are also dependent on the influence of the secondary equilibria of EDTA complex formation. Complexing reactions, which are equilibrium reactions, are simultaneously influenced by the following factors: solution pH and the presence of complexing agents which may also form a stabile complex with metal ions. The secondary reaction influence may be viewed and monitored through conditional stability constants. In the first part of the paper, the reaction of the formation of the Cu2+-ion complex with EDTA is analyzed beginning from the main reaction through various influences of secondary reactions on the complex Cu2+-EDTA: pH effect, complexation effect and hydrolysis effect. The equations are given for conditional stability constants, which include equilibrium reactions under actual conditions.

Studies on the Coordination Reaction of VO2+ and Tannic Acid in the Tannin Extract Desulfurization

2012 ◽  
Vol 239-240 ◽  
pp. 1573-1576
Author(s):  
Zhu Qing Gao ◽  
Xiao Dong Cai ◽  
Kai Cheng Ling
Keyword(s):  
Stability Constants ◽  
Tannic Acid ◽  
Ph Value ◽  
Protonation Constants ◽  
Conditional Stability ◽  
Tannin Extract ◽  
Acid Effect ◽  
Different Temperatures ◽  
The Stability ◽  
Apparent Stability

At different temperatures, the protonation constants of tannic acid and the complex apparent stability constants between tannic acid and VO2+ were determined by using pH potentimetric method. The results showed that the protonation constants and the complex apparent stability constants slightly decreased with the raising temperature. In accordance with the pH value in the tannin extract technology, the conditional stability constants of the complex were calculated on the basis of the acid effect of tannic acid and the hydrolysis effect of VO2+. It was found that pH greatly affected the stability constants of the complex , so pH must be strictly controlled in the tannin extract technology.

Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be2+ ion

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.

Effect of pH, humus concentration and molecular weight on conditional stability constants of cadmium

1988 ◽  
Vol 22 (11) ◽  
pp. 1381-1388 ◽  
Author(s):  
Jan John ◽  
Brit Salbu ◽  
Egil T. Gjessing ◽  
Helge E. Bjørnstad
Keyword(s):  
Molecular Weight ◽  
Stability Constants ◽  
Conditional Stability ◽  
Effect Of Ph ◽  
Conditional Stability Constants

scholarly journals Metal Ion-Binding Properties of the Diphosphate Ester Analogue, Methylphosphonylphosphate, in Aqueous Solution

1999 ◽  
Vol 6 (6) ◽  
pp. 321-328 ◽  
Author(s):  
Bin Song ◽  
Jing Zhao ◽  
Fridrich Gregáň ◽  
Nadja Prónayová ◽  
S. Ali A. Sajadi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Minor Role ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ph Titration ◽  
Role Based ◽  
The Stability ◽  
A Minor ◽  
Complex Stabilities

The stability constants of the 1:1 complexes formed between methylphosphonylphosphate (MePP3-), CH3P(O)2--O-PO32- , and Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+,​ or Cd2+ (M2+) were determined by potentiometric pH titration in aqueous solution (25 C° ; l = 0.1 M, NaNO3 ). Monoprotonated M(H;MePP) complexes play only a minor role. Based on previously established correlations for M2+ -diphosphate monoester complex-stabilities and diphosphate monoester β-group. basicities, it is shown that the M(Mepp)- complexes for Mg2+ and the ions of the second half of the 3d series, including Zn2+ and Cd2+, are on average by about 0.15 log unit more stable than is expected based on the basicity of the terminal phosphate group in MePP3-. In contrast, Ba(Mepp)- and Sr(Mepp)- are slightly less stable, whereas the stability for Ca(Mepp)- is as expected, based on the mentioned correlation. The indicated increased stabilities are explained by an increased basicity of the phosphonyl group compared to that of a phosphoryl one. For the complexes of the alkaline earth ions, especially for Ba2+, it is suggested that outersphere complexation occurs to some extent. However, overall the M(Mepp)- complexes behave rather as expected for a diphosphate monoester ligand.

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