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21.
S. M. Sawant 《Journal of Radioanalytical and Nuclear Chemistry》2001,249(3):613-616
Solvent extraction of uranium(VI) from aqueous solutions of ammoniumthiocyanate has been investigated in the presence of dibenzo-18-crown-6. Uranium(VI)was quantitatively extracted from 1.0M ammonium thiocyanate using 0.01M dibenzo-18-crown-6in nitrobenzene. Back extraction of U(VI) was quantitative with various strippingagents. Separation of U(VI) from other elements was achieved from binary aswell as multicomponent mixtures. Uranium was determined in monazite sand andsyenite rock samples. The method is very simple, rapid and highly reproducible(approximately ±2%). 相似文献
22.
A solution of n-octylaniline in chloroform extracts rhenium selectively from 0.12–0.16 M nitric acid medium. Rhenium from the organic phase is backstripped with 5% aqueous ammonia solution and estimated spectrophotometrically with 5-chloro-2-hydroxythiobenzhydrazide (5-Cl-2-OHTBH). 5-Cl-2-OHTBH forms a blue complex with rhenium on heating in the acidity range 0.40–3.5 M HCl. The complex is extracted into chloroform and its absorbance is measured at 580 nm. The complex is stable for more than 12 h with a molar extinction coefficient of 9.0 × 103l mole−1 cm−1 and a Sandell sensitivity of 0.019 μg cm2. 相似文献
23.
The stability constants of the fluoride complexes of cerium(IV) in 1 M (HClO(4), NaClO(4)) medium have been measured potentiometrically using a fluoride ion-selective electrode. Quantitative oxidation of cerium to its tetravalent state and its stabilisation in the perchlorate medium were accomplished by oxidation with AgO followed by quick addition of a known amount of fluoride ion. This procedure ensures stability of the oxidation state and prevents hydrolysis and polymerisation of Ce(IV). Logarithms of the average values of beta(1), beta(2), beta(3) and beta(4) were estimated to be 7.57+/-0.04, 14.50+/-0.03, 20.13+/-0.37 and 24.14+/-0.10 respectively. 相似文献
24.
R. M. Sawant N. K. Chaudhuri G. H. Rizvi S. K. Patil 《Journal of Radioanalytical and Nuclear Chemistry》1985,91(1):41-58
Complex formation between actinide(VI) and fluoride ions in aqueous solutions has been investigated using a fluoride ion selective electrode (F-ISE). As fairly high acidity was used to suppress hydrolysis of the actinide(VI) ions, significant liquid junction potentials (Ej) existed in the systems. An iterative procedure was developed for computing free hydrogen ion concentration [H+], as it could not be measured directly, using data obtained with F-ISE. Ej values were estimated from known [H+] and the stability constants of fluoride complexes of actinide(VI) ions were calculated following KING and GALLAGHER's method using a computer program. The stability constants were found to follow the order U(VI)>Np(VI)>Pu(VI). 相似文献
25.
The replacement of liquid acid catalyst by solid acids for the Friedel‐Crafts reaction of aromatic alkylation is a challenging task. Mixed oxide possessing spinel structures were found to catalyze the Friedel‐Craft benzylation of arenes. It was found that the reaction was very fast at 80 °C, hence the reaction was studied with respect to more substrate. The significant point was even at this temperature monobenzylation, with the para isomer predominating, was achieved. Mixed oxides were prepared by co‐precipitation method and were characterized by XRD technique. 相似文献
26.
Dess-Martin periodinane (DMP) mediated efficient synthesis of thioesters from the corresponding aldehydes under mild conditions is described. 相似文献
27.
Sawant Jyoti D. Patil Kranti K. Gokavi Gavisiddappa S. 《Transition Metal Chemistry》2019,44(2):153-159
Transition Metal Chemistry - Oxidation of paracetamol by the Anderson-type hexamolybdocobaltate(III) anion [H6CoIIIMo6O24]3− was investigated at pH values of 1 and 2 in aqueous medium. The... 相似文献
28.
29.
The total syntheses of the two aryl C-glycoside natural products diospongins A and B are described. The key reactions involved stereoselective reductions of the appropriate oxocarbenium cations that were derived from a common delta-lactone intermediate. 相似文献
30.
M. Hasan T. B. Pawar A. B. Sawant 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(3):429-433
The densities and viscosities of tetra-n-alkylammonium bromides, R4NBr (R=CH3 to C4H9), NaBPh4 and NaBr have been measured in 0, 10, 30, 50, 70, 90, and 100 wt % ethanol + water at 303.15 K. From the densities, apparent and limiting partial molar volumes of the electrolytes and ions in these mixture have been evaluated. The viscosity data have been analyzed with the help of Jones-Dole equation and the viscosity B-coefficients have been determined. The viscosity B-coefficients are further split up in to their ionic contributions. 相似文献