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).

Spectrophotometric study of the effect of sodium dodecyl sulphate on the acid-base behaviour of 4-(2-pyridylazo)-resorcinol

1991 ◽  
Vol 56 (4) ◽  
pp. 785-795 ◽  
Author(s):  
Jiří Bílý ◽  
Ludmila Čermáková ◽  
Jiří Knapp
Keyword(s):  
Surface Tension ◽  
Critical Micelle Concentration ◽  
Sodium Dodecyl Sulphate ◽  
Azo Dye ◽  
Dissociation Constants ◽  
Sodium Dodecyl ◽  
Spectrophotometric Study ◽  
Acid Base ◽  
Strong Electrolytes ◽  
The Given

The values of the apparent dissociation constants of the azo dye 4-(2-pyridylazo)-resorcinol (PAR) have been found in the presence of sub- and supercritical concentrations of the anionogenic tenside sodium dodecyl sulphate (SDS) and the effects of the strong electrolytes NaCl and NaNO3 were also evaluated. In both electrolytes, the pKan values initially are independent of the SDS concentration and then increase. Spectrophotometric and surface tension measurements were employed to determine the critical micelle concentration (cmc) of SDS alone and in the presence of PAR and the given electrolytes. The determined cmc values were in the range 0.20–3.02 mmol l-1 and dependent on the type and concentration of the particular additive.

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.

Extraction of hafnium by means of some substituted 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-ones

1981 ◽  
Vol 46 (8) ◽  
pp. 1901-1905 ◽  
Author(s):  
Oldřich Navrátil ◽  
Jiří Smola
Keyword(s):  
Ionic Strength ◽  
Aqueous Phase ◽  
Dissociation Constants ◽  
Parent Substance ◽  
Benzoyl Group ◽  
Extraction Constants ◽  
Extraction Parameters ◽  
Substituted 1

Distribution between aqueous phase and benzene or chloroform was studied for 1-phenyl-3-methyl-4-benzoylpyrazol-5-ones with 2-chloro, 4-methoxy, 3-nitro, and 4-nitro substitution in the benzoyl group (ionic strength of the aqueous phase 0.1) and for hafnium in their presence (ionic strength 2.0). The distribution and dissociation constants of the reagents and the extraction constants of their hafnium complexes were determined. Hafnium was found to be extracted as the HfA4 species. The extraction parameters of the derivatives in question do not differ substantially from those of the parent substance.

scholarly journals Optical Properties of Dissolved Organic Matter in Finnish and Estonian Lakes

2003 ◽  
Vol 34 (4) ◽  
pp. 361-386 ◽  
Author(s):  
L. Sipelgas ◽  
H. Arst ◽  
K. Kallio ◽  
A. Erm ◽  
P. Oja ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Natural Waters ◽  
Mean Value ◽  
Published Data ◽  
Optical Parameters ◽  
Exponential Approximation ◽  
Absorption Coefficients ◽  
Specific Absorption ◽  
The Mean

The main objective of the present study is to test various methods for describing the absorption spectra of coloured dissolved organic matter (CDOM) and to determine the numerical values of some optical parameters of CDOM in lakes with diverse water quality. First, the parameters of an exponential model in different spectral intervals were determined. In addition, the suitability of some other models for the approximation of CDOM spectra was estimated. Specific absorption coefficients of CDOM were calculated from the absorption coefficients and dissolved organic carbon (DOC) concentrations. The experimental initial data were differences between spectral attenuation coefficients of filtered and distilled water. Two datasets were used: 1) for 13 Estonian and 7 Finnish lakes (altogether 404 spectra between 350 and 700 nm) measured by the Estonian Marine Institute (EMI); 2) for 10 Finnish lakes (73 spectra) measured by the Finnish Environment Institute (FEI). The spectra of CDOM absorption coefficients (aCDOM) were calculated from experimental data taking into account the correction due to scattering properties of colloids in the filtered water. The total content of CDOM in natural waters of Estonian and Finnish lakes was expressed by means of aCDOM at the wavelength of 380 nm. It varied significantly, from 0.71 to 19.5 m−1, the mean value (of all the investigated lakes) being around 6.6 m−1. Slopes of the exponential approximation varied widely, from 0.006 to 0.03 nm−1. Averaged over all lakes values of slope for the interval 380-500 nm obtained from the EMI dataset are close to those obtained from the FEI dataset: from 0.014 nm−1 (without correction) to 0.016-0.017 nm-1 (with different types of correction). These results are in good correspondence with most published data. Attempts to describe the spectra in the region of 350-700 nm by means of hyperexponential functions (∽ exp(-αλη)) show that: (1) η < 1 (in the case of traditional exponential approximation η = 1); (2) a promising idea is to seek the best fit only for wavelengths λ > λ1, where λ1 will be chosen taking into account the real shape of aCDOM spectra. The mean value of the specific absorption coefficient (a*CDOM) at the wavelength 380 nm obtained in this study (0.44 L mg−1 m−1) is close to the values published in the literature, if we assume that a*CDOM (380) is calculated using the data of dissolved organic matter (DOM). The optically non-active fraction of DOM in our study was high and therefore a*CDOM (380) was considerably higher (1.01 L mg−1 m−1) than a*CDOM (380). The results of the present work could be used in the modeling of underwater light field as well as in the interpretation of radiation measurements and optical remote sensing results.

The extraction of alkali metal picrates by polyurethane foam using crown ether

1981 ◽  
Vol 59 (10) ◽  
pp. 1490-1496 ◽  
Author(s):  
Anjum S. Khan ◽  
W. G. Baldwin ◽  
A. Chow
Keyword(s):  
Crown Ether ◽  
Alkali Metal ◽  
Polyurethane Foam ◽  
Dissociation Constants ◽  
Extraction Constant ◽  
Ion Pair ◽  
Constant Sequence ◽  
Extraction Constants ◽  
The Stability ◽  
Ether Complex

The distribution of alkali metal picrates between water and polyurethane foam was studied in the presence of dicyclohexyl 18-crown-6 (DCHC-6). The extraction constants and dissociation constants for the ion pair (MCrA) in polyurethane foam were determined. The extraction constant sequence of the alkali metal ions with DCHC-6 is K+ > Rb+ > Cs+ > Na+ and mainly depends on the stability of the alkali metal – crown ether complex.

scholarly journals ACID-BASE PROPERTIES OF -UNSATURATED KETONES OBTAINED FROM REACTION OF 5-FORMYL-8-HYDROXYQUINOLINE WITH P-SUBSTITUTED ACETOPHENONES

2019 ◽  
Vol 16 (31) ◽  
pp. 755-764
Author(s):  
Roberto FERNANDEZ-MAESTRE ◽  
Alonso J MARRUGO-GONZÁLEZ
Keyword(s):  
Electron Donor ◽  
Opposite Effect ◽  
Dissociation Constants ◽  
Phenyl Group ◽  
Hydroxyl Group ◽  
Ultraviolet Spectroscopy ◽  
Acid Base ◽  
Unsaturated Ketones ◽  
Ph Values ◽  
Phenyl Fragment

Chalcones (α,β-unsaturated ketones) containing aromatic or heterocyclic radicals are highly reactive, allowing the synthesis of novel organic compounds. In this study, the dissociation constants (pKa) of seven chalcones derived from 8-hydroxyquinoline were determined and the influence on dissociation of substituents in the phenyl group (-CH3, -OCH3, -N(CH3)2, -Cl, -Br, and -NO2) was analysed. pKa values are important because they determine the pH at which ligands are fully deprotonated -when they show their maximum chelating properties- and determine the ligands interactions at different pH values. The chalcones’ pKa’s were calculated by visible ultraviolet spectroscopy in a water-ethanol (1:1) mixture using the Henderson-Hasselbach equation. It was shown that the 8-hydroxyquinolinic fragment has a large electron donor effect on the π system of the chalcones. The introduction of substituents (R) in the phenyl fragment of the chalcones slightly affected the dissociation of the hydroxyl group and the protonation of the nitrogen in the hydroxyquinoline fragment. The acceptor substituents (Cl, Br, NO2) increased the polarity of OH- and its acidity. Nitrogen protonation decreased electron donor properties of this fragment, and deprotonation of the hydroxyl caused the opposite effect. Substituents introduction in the phenyl fragment slightly affected hydroxyl group dissociation and nitrogen protonation.

scholarly journals pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary

2009 ◽  
Vol 6 (8) ◽  
pp. 1539-1561 ◽  
Author(s):  
A. F. Hofmann ◽  
J. J. Middelburg ◽  
K. Soetaert ◽  
F. J. R. Meysman
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Dissociation Constants ◽  
Time Variable ◽  
Scheldt Estuary ◽  
Biogeochemical Processes ◽  
Acid Base ◽  
Ph Profile ◽  
Proton Production ◽  
Co2 Degassing

Abstract. A new pH modelling approach is presented that explicitly quantifies the influence of biogeochemical processes on proton cycling and pH in an aquatic ecosystem, and which accounts for time variable acid-base dissociation constants. As a case study, the method is applied to investigate proton cycling and long-term pH trends in the Scheldt estuary (SW Netherlands, N Belgium). This analysis identifies the dominant biogeochemical processes involved in proton cycling in this heterotrophic, turbid estuary. Furthermore, information on the factors controlling the longitudinal pH profile along the estuary as well as long-term pH changes are obtained. Proton production by nitrification is identified as the principal biological process governing the pH. Its acidifying effect is mainly counteracted by proton consumption due to CO2 degassing. Overall, CO2 degassing generates the largest proton turnover in the whole estuary on a yearly basis. The main driver of long-term changes in the mean estuarine pH over the period 2001 to 2004 is the decreasing freshwater flow, which influences the pH directly via a decreasing supply of dissolved inorganic carbon and alkalinity, and also indirectly, via decreasing ammonia loadings and lower nitrification rates.

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