Physico-chemical investigation on the complexes of indium(III) with Mercapto-, Hydroxy-, and Amino-substituted propionic acid

1972 ◽  
Vol 25 (5) ◽  
pp. 929 ◽  
Author(s):  
R Sarin ◽  
KN Munshi
Keyword(s):  
Formation Constants ◽  
Alternative Methods ◽  
Potentiometric Studies ◽  
Ph Titration ◽  
Physico Chemical ◽  
Different Temperatures ◽  
Indium 111 ◽  
The Stability ◽  
Titration Technique ◽  
Stepwise Formation

Potentiometric studies have been carried out on the metal complexes of indium(111) with β-mercaptopropionic, β-hydroxypropionic, and β-aminopropionic acid. The Calvin-Bjerrum pH-titration technique, as used by Irving and Rossotti, has been applied to determine the stepwise formation constants of the complexes. The logK values have been computed by alternative methods. Thermodynamic formation constants have been obtained by extrapolation of the values at various ionic concentrations. The values of overall changes in ΔG, ΔH, and ΔS accompanying complex formation have been evaluated at three different temperatures at an ionic strength of 0.lM (NaClO4). The stability constant of the indium(111) complex decreases as the subsituted group changes from SH to OH to NH2.

The polarography of glycine metal complexes and the determination of stepwise formation constants

1961 ◽  
Vol 14 (4) ◽  
pp. 562 ◽  
Author(s):  
DP Mellor ◽  
HA McKenzie
Keyword(s):  
Metal Complexes ◽  
Formation Constants ◽  
Substantial Agreement ◽  
Titration Method ◽  
Ph Titration ◽  
Polarographic Behaviour ◽  
The Stability ◽  
Titration Technique ◽  
Stepwise Formation

The polarography of metal-glycine complexes has been studied with a view to assessing its usefulness in measuring the stability of metal complexes, especially the stepwise formation constants. It is shown that the equation derived by De Ford and Hume (1951) may be transformed in a way that makes possible the calculation of both overall and stepwise stoichiometric constants from experimental data obtained with solutions of constant ionic strength. Problems in the use of maximum suppressors and buffer ions are considered. Stoichiometric stepwise stability constants for the glycine complexes of copper(II) and cadmium(II) have been determined : (i) polarographically and (ii) by the pH- titration method of Irving and Rossotti (1954a, 1954b). The values obtained by the two methods agree reasonably well. Problems of hydrolysis and precipitation arise with t8he lead(II) complexes. The zinc(II) complexes exhibit anomalous polarographic behaviour. The reasons for this behaviour are briefly discussed. Although the polarographic technique is capable of yielding values for step constants in substantial agreement with those obtained by the pH-titration technique, there is evidence that it in not so generally applicable as the latter.

Physicochemical investigation on thiomalate complexes of nickel

1968 ◽  
Vol 21 (3) ◽  
pp. 641 ◽  
Author(s):  
RS Saxena ◽  
KC Gupta ◽  
ML Mittal
Keyword(s):  
Aqueous Medium ◽  
Stability Constants ◽  
Alternative Methods ◽  
Acid System ◽  
Kcal Mole ◽  
Physicochemical Investigation ◽  
Different Temperatures ◽  
The Stability ◽  
Ph Range ◽  
Deep Violet

Potentiometric and conductometric studies of the nickel-thiomalic acid system, in aqueous medium of 0. lM KNO3, reveal the formation of two complexes; one light violet 1 : 1 predominating at pH 6.5-7.5 and another deep violet 1 : 2 in the pH range 8.5-10.0. The stability constants of the complexes formed have been determined by applying Calvin and Melchior's extension of Bjerrum's method at three different temperatures and were further refined by using alternative methods. The logK values (final) for 1 : 1 and 1 : 2 complexes at 20, 25, and 30� have been found to be 7.86, 7.87, 7.96, and 6.24, 6.31, 6.39 respectively. The values of the overall changes in ΔG, ΔH, and ΔS accompanying the reaction have also been evaluated at 25� and found to be -19.31 kcal/mole, -8.77 kcal/mole, and +35.36 cal/deg respectively.

Physico-chemical Characteristics and Oxidative Stability of Date-Pits Oil during Storage at Different Temperatures

2016 ◽  
Vol 12 (4) ◽  
pp. 385-393
Author(s):  
Naima Al-Kharousi ◽  
Mohammed Al-Khusaibi ◽  
Ismail Al-Bulushi ◽  
Nejib Guizani ◽  
Mostafa Waly ◽  
...  
Keyword(s):  
Oxidative Stability ◽  
Value Added ◽  
Stability Index ◽  
Acid Value ◽  
Food Ingredients ◽  
C Storage ◽  
Physico Chemical ◽  
Different Temperatures ◽  
The Stability ◽  
Date Pits

Abstract In this study, oxidative stability of date-pits (i. e. Khalas variety) was investigated during storage as a function of temperature. The stability of date-pits oil was determined by measuring acid value (AV), peroxide value (PV), p-anisidine value (PAV), tocopherol and oxidative stability index. Initial characteristics of oil were assessed by measuring its physico-chemical and melting characteristics, fatty acids composition and aflatoxin. Storage of date-pits caused highest reduction in linoleic acid (C18:2, ω6) followed by oleic acid (C18:1, ω9). AV, PV and PAV of the fresh oil were 1.41 mg KOH/g oil, 3.30 meq/kg oil and 0.60, respectively. These values increased linearly at slower rate in the case of 30 °C storage, while sharp rise was observed after 40 days in cases of 100 and 150 °C storage (p < 0.05). The results of this study indicate that date pits oil had a good oxidative and thermal stability and could thus be used to develop value-added food ingredients.

scholarly journals Conductometric Studies of Thermodynamics of 1,10-Didecyl-1,10-diaza-18-crown-6 Complexes with , , , , , , and Ions in Acetonitrile, Methanol, and Ethanol Solutions

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Mehdi Taghdiri ◽  
Mahmood Payehghadr ◽  
Reza Behjatmanesh-Ardakani ◽  
Sirous Movahhedi ◽  
Farzaneh Nourifard
Keyword(s):  
Formation Constants ◽  
Molar Conductance ◽  
Versus Plot ◽  
Ratio Data ◽  
Different Temperatures ◽  
Enthalpy And Entropy Changes ◽  
Enthalpy And Entropy ◽  
The Stability ◽  
Complexation Reactions ◽  
Cation Size

The complexation reactions between 1,10-didecyl-1,10-diaza-18-crown-6 (DD18C6) and , , , , , and ions were studied conductometrically in acetonitrile, methanol, and ethanol at various temperatures. The formation constants of the resulting 1 : 1 complexes were calculated from the computer fitting of the molar conductance-mole ratio data at different temperatures. In the solvents studied, the stability of the resulting complexes varied in the order acetonitrile ≫ methanol > ethanol. The enthalpy and entropy changes of the complexation reactions were evaluated from the temperature dependence of formation constants. The versus plot of thermodynamic data obtained shows a linear correlation indicating the existence of enthalpy-entropy compensation in the complexation reactions. The ab initio studies calculated at B3LYP/6-31G level of theory indicate that the binding energy of complexes decreases with increasing cation size in the gas phase. The experimental data obtained in the solvents show different trends so that the stability constant of Li+and Mg2+complexes is lower than other alkali and alkaline earth ions, respectively due to the solvation of these small ions in solution.

Stability of Ceftazidime and Heparin in Four Different Types of Peritoneal Dialysis Solutions

2018 ◽  
Vol 38 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Surendra Kandel ◽  
Syed Tabish R. Zaidi ◽  
S. Troy Wanandy ◽  
Long C. Ming ◽  
Ronald L. Castelino ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
High Performance ◽  
Anticoagulant Activity ◽  
Storage Conditions ◽  
Color Changes ◽  
Physico Chemical ◽  
Different Temperatures ◽  
The Stability ◽  
Dialysis Solutions ◽  
Potential Use

Background Intraperitoneal (IP) administration of ceftazidime is recommended for the treatment of peritoneal dialysis-associated peritonitis (PDAP) from Pseudomonas. Patients with PDAP may also need IP heparin to overcome problems with drainage of turbid peritoneal dialysis (PD) fluids and blockage of catheters with fibrin. Physico-chemical stability of ceftazidime and heparin, and biological stability of heparin in many types of PD solutions is unknown. Therefore, we investigated the stability of ceftazidime and heparin in 4 types of PD solutions. Methods A total of 12 PD bags (3 for each type of solution) containing ceftazidime and heparin were prepared and stored at 4°C for 120 hours, and then at 25°C for 6 hours, and finally at 37°C for 12 hours. An aliquot was withdrawn after predefined time points and analyzed for the concentration of ceftazidime and heparin using high-performance liquid-chromatography (HPLC). Samples were assessed for pH, color changes, particle content, and anticoagulant activity of heparin. Results Ceftazidime and heparin retained more than 91% of their initial concentration when stored at 4°C for 120 hours followed by storage at 25°C for 6 hours and then at 37°C for 12 hours. Heparin retained more than 95% of its initial activity throughout the study period. Particle formation was not detected at any time under the storage conditions. The pH and color remained essentially unchanged throughout the study. Conclusions Ceftazidime-heparin admixture retains its stability over long periods of storage at different temperatures, allowing its potential use for PDAP treatment in outpatient and remote settings.

scholarly journals Physico-chemical studies of some aminobenzoic acid hydrazide complexes

2004 ◽  
Vol 69 (4) ◽  
pp. 255-264 ◽  
Author(s):  
Abd El ◽  
Abd El ◽  
Gamel El ◽  
Abd El
Keyword(s):  
Acid Hydrazide ◽  
Conductometric Titration ◽  
Aminobenzoic Acid ◽  
X Ray ◽  
Physico Chemical ◽  
Coordination Process ◽  
Different Temperatures ◽  
Chemical Studies ◽  
The Stability ◽  
Thermal Stability Of

The stability constants and related thermodynamic functions characterizing the formation of divalent Ni, Cu, Zn, Cd and Hg complexes with o- and p-aminobenzoic acid hydrazide were determined potentiometrically at different temperatures. The formations of the complexes are endothermic processes. The formed bonds are mainly electrostatic. Conductometric titration was carried out to determine the stoichiometry and stability of the formed complexes. The structures of complexes were characterized by their IR, 1H-NMR and 13C-NMR spectra, as well as X-ray diffractograms. The coordination process takes place through the carbonyl group and the terminal hydrazinic amino group. The thermal stability of the complexes was followed in the temperature range 20?600 ?C.

scholarly journals Computer Assisted Thermal Complexation Studies of Vanadium with Benzodiazepine Drugs

2019 ◽  
Vol 31 (10) ◽  
pp. 2351-2356
Author(s):  
N. Sharma ◽  
V.K. Vashistha ◽  
U.R. Sharma
Keyword(s):  
Entropy Change ◽  
Ion Concentration ◽  
Computer Assisted ◽  
Ph Titration ◽  
Acid Media ◽  
Hydrogen Ion Concentration ◽  
Different Temperatures ◽  
Gibb’S Free Energy ◽  
Complexation Reactions ◽  
Titration Technique

The complexing tendency of vanadium with nifoxipam and lorazepam were carried out by pH metric titration technique in aqueous acid media at different temperatures (298, 308 and 318 K) and an ionic strength of 0.2 M. The degree of complexation was investigated at different pH values. Potentionmetric measurement of hydrogen ion concentration was also studied with the degree of complex formation. The proton-ligand and metal-ligand stability constants were resolved by modified Calvin-Bjerrum pH titration technique (Irving and Rossitti) using computer programming. The important thermodynamic parameters such as Gibb's free energy change (ΔG), entropy change (ΔS) and enthalpy change (ΔH) for the complexation reactions were calculated. The formation of metal complexes was found to be spontaneous, exothermic and conducive in nature at lower temperatures.

scholarly journals Thermodynamics of the complexation between salicylaldehyde thiosemicarbazone with Cu2+ ion in methanol +1,4-dioxane binary solutions

2014 ◽  
Vol 79 (5) ◽  
pp. 565-578 ◽  
Author(s):  
Rashmidipta Biswas ◽  
Dhiraj Brahman ◽  
Biswajit Sinha
Keyword(s):  
Mixed Solvents ◽  
Formation Constants ◽  
Molar Conductance ◽  
Binary Solvent ◽  
Complexation Reaction ◽  
Solvent Mixtures ◽  
Conductance Data ◽  
Different Temperatures ◽  
Uv Visible ◽  
The Stability

The complexation reaction between salicylaldehyde thiosemicarbazone, abbreviated as STSC, with Cu2+ ion was studied in the binary mixtures of methanol + 1,4-dioxane binary by using UV-Visible spectrophotometric and conductometric methods at different temperatures. The formation constants (Kf) for the 1:1 complex, Cu2+-STSC, were calculated from computer fitting of the absorbance and molar conductance data against various mole ratios (cM:cL or cL:cM) in different binary solvent mixtures. A non-linear correlation was observed for the variation of logKf for the complex against the solvent compositions. Various thermodynamic parameters (?H, ?S and ?G) for the formation of Cu2+-STSC complex were also determined from the temperature dependence of the stability constants (Kf). The results showed that the complexation reaction is affected by the nature and composition of the mixed solvents.

Chelation Reactions of Adenine

1972 ◽  
Vol 27 (6) ◽  
pp. 688-690 ◽  
Author(s):  
Ram Nayan ◽  
Arun K. Dey
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Metal Ions ◽  
Formation Constants ◽  
Ph Titration ◽  
Ionic Concentrations ◽  
Antimitotic Drug ◽  
Titration Technique

Chelation reactions of the antimitotic drug, 6-amino-purine (adenine; abbr. ADN) with the metal ions: Be(II), Al(III), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Pb(II), and UO2(II) have been investigated in aqueous solution at 30° using Bjerrum-Calvin pH titration technique. The formation constants have been determined at various ionic concentrations, and have been extrapolated to zero ionic strength to get the thermodynamic values of the constants.

THE STABILITY OF METALLIC COMPLEXES OF TWO DIMETHYLPHENANTHROLINES

1963 ◽  
Vol 41 (5) ◽  
pp. 1135-1141 ◽  
Author(s):  
D. A. Brisbin ◽  
W. A. E. Mcbryde
Keyword(s):  
Ionic Strength ◽  
Cobalt Complexes ◽  
Formation Constants ◽  
Iron Cobalt ◽  
Cobalt Nickel ◽  
Nickel Copper ◽  
Bivalent Iron ◽  
The Stability ◽  
Partition Method ◽  
Stepwise Formation

The stepwise formation constants for the complexes formed by 5,6-dimethyl- and 4,7-dimethyl-1,10-phenanthroline with bivalent iron, cobalt, nickel, copper, and zinc were determined by a partition method. The measurements were made at 25 °C and in aqueous solutions having an ionic strength maintained at 0.1. The enhanced basicity of the ligands compared to the parent phenanthroline is paralleled by increased stability of the metallic complexes. The abnormally high formation constants of the cobalt complexes suggest oxidation to cobalt (III).

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