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.

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.

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>

The effect of surfactants on the acid-base behaviour of methyl red. Part I. A spectrophotometric comparison of the effect of CPB and SDS

1990 ◽  
Vol 55 (6) ◽  
pp. 1491-1499 ◽  
Author(s):  
Jana Jirasová ◽  
Jiří Bílý ◽  
Ludmila Čermáková
Keyword(s):  
Absorption Spectra ◽  
Dissociation Constants ◽  
Methyl Red ◽  
Acid Base ◽  
Absorption Bands ◽  
Gaussian Shape ◽  
The Individual ◽  
Sds Surfactant

The effect of a cationic (CPB) and an anionic (SDS) surfactant on the bands in the absorption spectra of methyl red was studied. The interactions of methyl red with the two surfactants were monitored on the basis of the changes in the absorption curves that were mathematically deconvoluted into Gaussian shape absorption bands. The methyl red dissociation constants were determined in the presence of the two surfactants at sub- and supercritical micelle concentrations. The methyl red conditional dissociation constants changed by ΔpKa = -1.47 for c(CPB) = 5 mmol l-1 and ΔpKa = 0.81 for c(SDS) = 4 mmol l-1. The contributions of the individual forms of methyl red to the interactions with CPB and SDS were discussed.

The use of 2-(2-hydroxyphenylazo)-7-oxo-5,5-dimethyl-4,5,6,7-tetrahydrobenzothiazole as an extractant for Cu(II), Ni(II), Co(II), Pb(II) and Cd(II)

1981 ◽  
Vol 46 (10) ◽  
pp. 2382-2389 ◽  
Author(s):  
Margita Vačková ◽  
Emil Kuchár ◽  
Viera Šuriková
Keyword(s):  
Stability Constants ◽  
Azo Dye ◽  
Dissociation Constants ◽  
Optical Parameters ◽  
Absorption Coefficients ◽  
Acid Base ◽  
Extraction Constants

The heterocyclic azo dye, 2-(2-hydroxy-5-ethylphenylazo)-7-oxo-5,5-dimethyl-4,5,6,7-tetrahydrobenzothiazole (I), was prepared. The acid-base and optical parameters of the azo dye were found spectrophotometrically and the molar absorption coefficients and concentration dissociation constants were determined. The formation of the chelates of compound (I) with Cu(II), Ni(II), Pb(II) and Cd(II) was studied. The molar absorption coefficients and stability constants of the chelates were determined by calculations, graphical and logarithmic analysis, based on data from the A = f(pH) curves. The region of optimal extraction and the extraction constants were found for the chelates of I with Cu(II), Ni(II), Co(II) and Pb(II).

Acid-base properties of Tunisian palygorskite in aqueous medium

2007 ◽  
Vol 43 (7) ◽  
pp. 795-802 ◽  
Author(s):  
N. Frini-Srasra ◽  
A. Kriaa ◽  
E. Srasra
Keyword(s):  
Aqueous Medium ◽  
Acid Base ◽  
Base Properties

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.

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.

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