Quantitative description of the changes in the acid-base properties of bromocresol green in the presence of submicelle and micelle concentrations of cationic tenside-Septonex

1983 ◽  
Vol 48 (5) ◽  
pp. 1290-1304 ◽  
Author(s):  
Josef Havel ◽  
Irena Burešová-jančářová ◽  
Vlastimil Kubáň
Keyword(s):  
Dissociation Constant ◽  
Equilibrium Constant ◽  
Dissociation Constants ◽  
Quantitative Description ◽  
Polymeric Micelle ◽  
Bromocresol Green ◽  
Acid Base ◽  
Experimental Conditions ◽  
Spectrophotometric Methods ◽  
Base Properties

The effect of cationic surface-active substances - tensides - on the acid-base and optical properties of anionic organic analytical reagents was studied by spectrophotometric methods on the example of bromocresol green with Septonex in the submicelle and micelle tenside concentration regions. The acid-base properties of bromocresol green under the given experimental conditions depend on the concentrations of the tenside and reagent and on the type and concentration of the inert electrolyte. Changes in the conditional dissociation constant of the reagent were quantitatively described by equations that were derived from the relationships for the dissociation constant of the acid-base transition of the reagent LH/L-, the equilibrium constant for formation of the stoichiometric ion-associates between the tenside T+ and the anionic acid-base form of the reagent L- or the anion of the inert electrolyte X- and the equilibrium constant for formation of the polymeric micelle aggregates (T+)n. The experimental values of the conditional dissociation constants for bromocresol green for various tenside or inert electrolyte concentrations are in good agreement with these theoretically derived relationships.

scholarly journals Analysis of acid-base properties of some p-substituted aromatic hydrazones in aqueous perchloric acid by spectrophotometric and semiempirical methods

2014 ◽  
Vol 33 (1) ◽  
pp. 85 ◽  
Author(s):  
Mirjana Stojan Jankulovska ◽  
Ilinka Spirevska
Keyword(s):  
Perchloric Acid ◽  
Dissociation Constants ◽  
Protonated Form ◽  
Heat Of Formation ◽  
Semiempirical Methods ◽  
Acid Base ◽  
Spectrophotometric Methods ◽  
Aqueous Perchloric Acid ◽  
The Stability ◽  
Base Properties

<p>The acid-base properties of some <em>p</em>-substituted aromatic hydrazones were examined in aqueous perchloric acid medim by spectrophotometric methods. The possible site where the proton may take place and the stability of the protonated form was discussed using the values of the total energy, binding energy, heat of formation and proton affinity calculated according to the semiempirical methods AM1 and PM3. Furthermore, the stability of the protonated forms, as well as, the stability of the isomers (<em>E</em> and <em>Z</em>) was discussed. Electronic absorption studies were utilized for determination of the dissociation constants of the protonated form (p<em>K</em><sub>BH</sub><sup>+</sup>), numerically and graphically, at different ionic strength (0.1, 0.25 and 0.5 mol/dm<sup>3</sup>), as well as, thermodynamic dissociation constants.  The influence of the solvent on the appearance of the recorded spectra was compensated by the use of the method of characteristic vector analysis (CVA).</p><p> </p>

Acid-base properties of 1,3-diphenyl-5-(1H-tetrazol-2-yl)formazan and 1,3-diphenyl-5-(2H-1,2,4-triazol-3-yl)formazan

1982 ◽  
Vol 47 (11) ◽  
pp. 2882-2889
Author(s):  
Nadezhda Likhareva ◽  
Ladislav Šůcha ◽  
Miloslav Suchánek
Keyword(s):  
Computer Program ◽  
Dissociation Constants ◽  
Acid Base ◽  
New Compounds ◽  
Base Properties

Two new compounds from the formazan series, viz. 1,3-diphenyl-5-(1H-tetrazol-2-yl)formazan and 1,3-diphenyl-5-(2H-1,2,4-triazol-3-yl)formazan, were prepared, and the dissociation constants and molar absorptivities of all of their acid-base species were determined spectrophotometrically employing the SPEKTFOT computer program.

The Effect of Surfactants on the Acid-Base Behaviour of Methyl Red. Part II. A Spectrophotometric Comparison of the Effect of Triton X-100 and β-Cyclodextrin

1994 ◽  
Vol 59 (2) ◽  
pp. 322-329
Author(s):  
Jana Jirasová ◽  
Jiří Bílý ◽  
Ludmila Čermáková
Keyword(s):  
Dissociation Constant ◽  
Dissociation Constants ◽  
Methyl Red ◽  
Acid Base ◽  
Absorption Bands ◽  
Triton X

The effect of the non-ionogenic surfactant Triton X-100 (TX) and β-cyclodextrin (CD) on the absorption bands of methyl red was examined. The interactions of methyl red with the both substances were studied based on changes in the absorption curves after their resolution into Gaussian bands. The conditional dissociation constants of methyl red were determined at various concentrations of the additives (in the case of TX, both below and above its cmc value). At cTX = 0.06 mol l-1 the change in the conditional dissociation constant of methyl red was ∆pKa = -0.58 and at cCD = 6 mmol l-1 the ∆pKa value was identical.

scholarly journals EXPLORING OF ACID-BASIC PROPERTIES, DEVELOPMENT AND VALIDATION OF THE METHOD OF QUANTITATIVE DETERMINATION OF ORIGINAL PHARMACEUTICAL SUBSTANCE

2019 ◽  
Vol 8 (1) ◽  
pp. 66-71
Author(s):  
G. M. Alekseeva ◽  
V. F. Apraksin ◽  
Yu. E. Generalova
Keyword(s):  
Quantitative Determination ◽  
Active Compound ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Bromocresol Green ◽  
Acid Base ◽  
Indicator Method ◽  
Pharmaceutical Substance ◽  
Basic Properties

Introduction. The object of analysis was a newly synthesized organic substance, a derivative of 4-aminobenzoic acid and malonic ester  – 4,4’-(propandiamido) sodium dibenzoate, which has an antisteatotic effect. For the quantitative determination of pharmaceutical substances, it is preferable to use titrimetric methods of analysis, since they are absolute and allow us to estimate the content of the active compound in the substance without using standard samples. Aim. The objective of this work was to develop and validate a quantitative determination method for 4.4’-(propandiamido) sodium dibenzoate. Materials and methods. The analyzed compound is a salt of a weak dibasic acid, which exhibits basic properties in an aqueous solution; therefore, for its quantitative determination, a direct acid-base titration method (acidimetry) was proposed. The method of quantitative determination of the active compound in the substance 4,4’-(propandiamido) sodium dibenzoate will be used in future studies for routine analysis, therefore a visual (indicator) method for determining the end point of the titration has been chosen. To prove the suitability of the developed method and the possibility of obtaining reliable results of the quantitative content of the active compound in the newly synthesized pharmaceutical substance the used analytical method was validated. Results and discussion. The study of the acid-base properties of the newly synthesized substance was carried out using the method of potentiometric titration, on the basis of which the values of the dissociation constants were calculated. Using spreadsheets, the pKa1 and pKa2 values were calculated using a titration model of a multi-basic acid, the pKa values of which are 7.2 and 5.0. The titration curve that was constructed from the experimental data and the curve constructed from the calculated values of the dissociation constants almost completely overlapped with each other. Based on the data obtained, a 0.1% water-alcohol solution of bromocresol green (blue) with pT=4.6 was selected for titration, the color transition interval of which falls into the titration jump of the analyte. The developed methodology was validated according to the requirements of the XIV edition State Pharmacopoeia of the Russian Federation by the following indicators: specificity, linearity, accuracy, precision (convergence and internal reproducibility), robustness, analytical domain. Conclusion. As a result of the performed studies, the values of acid dissociation constants of the newly synthesized pharmaceutical substance 4,4’-(propandiamido) sodium dibenzoate were determined, and a method for quantitative determination was developed and validated using acidbase titration.

The optical and acid-base properties of chromatographically pure Chromazurol S, Eriochromazurol B and Eriochromcyanine R

1981 ◽  
Vol 46 (2) ◽  
pp. 354-367 ◽  
Author(s):  
Naděžda Pollaková-Mouková ◽  
Dagmar Gotzmannová ◽  
Vlastimil Kubáň ◽  
Lumír Sommer
Keyword(s):  
Aqueous Medium ◽  
Dissociation Constants ◽  
Absorption Coefficients ◽  
Acid Base ◽  
Chromazurol S ◽  
Base Transition ◽  
The Individual ◽  
Mixed Water ◽  
Base Properties

The positons of the absorption maxima and the values of the molar absorption coefficients of all the acid-base forms and the dissociation constants of the individual acid-base transition of chromatographically pure Chromazurol S, Eriochromazurol B and Eriochromcyanine R were found by graphical and numerical interpretation of the absorbance curves measured in aqueous medium and mixed water-ethanol and water-DMF medium. These values were compared with the values given in the literature.

Electrochemical Study of Acid-Base Properties of Some 2,5-Dihydro-1,3,4-thiadiazoles in Aqueous-Ethanolic Solutions

1998 ◽  
Vol 63 (1) ◽  
pp. 31-41
Author(s):  
Maria Turowska ◽  
Grzegorz Mloston ◽  
Pawel Krzyczmonik ◽  
Jacek Raczak ◽  
Jaroslaw Romanski
Keyword(s):  
Ionic Strength ◽  
Dissociation Constants ◽  
Mndo Method ◽  
Electrochemical Study ◽  
Acidic Properties ◽  
Acid Base ◽  
Weak Bases ◽  
Formation Enthalpies ◽  
Protonated Forms ◽  
Base Properties

The dissociation constants Ka for spherically crowded 2'- and 2,5-substituted thiadiazolines and their protonated forms in 45% (v/v) aqueous-ethanolic solutions (ionic strength m = 0.1) were determined using the pH-metric method. All the thiadiazoles are weak bases. Some of them showed also weak acidic properties. The formation enthalpies have been calculated using the MNDO method. On the basis of the obtained results the mechanism of the protonation process is discussed.

Acid-base properties of metals and glasses of Na2O.P2O5-xB2O3 system

1984 ◽  
Vol 49 (10) ◽  
pp. 2355-2362 ◽  
Author(s):  
Juraj Leško ◽  
Marie Dorušková ◽  
Jan Tržil
Keyword(s):  
Boron Oxide ◽  
A Priori ◽  
Optical Basicity ◽  
Galvanic Cell ◽  
Acid Base ◽  
Tetrahedral Configuration ◽  
Relative Basicity ◽  
Base Theory ◽  
Base Properties

Boron oxide in the Na2O.P2O5-x B2O3 system behaves as a Lux base. Its addition to Na2O.P2O5 brings about transformation of a Co(II) indicator from octahedral to tetrahedral configuration, increase in the optical basicity ΛPb(II), increase in the relative basicity of the melt as determined by means of a galvanic cell, and depolymerization reactions releasing PO43- ions. In the Na2O-B2O3 system free of P2O5, boron oxide behaves as a Lux acid. The amphoretic nature of B2O3 is explained in terms of Lux's acid-base theory extended in analogy with the protolysis theory. The theoretical optical basicity values do not indicate the amphoretic behaviour of B2O3 because in this approach boron oxide is a priori regarded as more acidic than Na2O.P2O5.

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