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31.
32.
The complex generated from 1/2[Ir(OMe)(cod)]2 and 4,4'-di-tert-butyl-2,2'-bipyridine catalyzes the regioselective borylation of ferrocenes, CpMn(CO)3 and CpMo(CO)3CH3 with a stoichiometric amount of B2pin2. 相似文献
33.
The reagent 5,6-diphenyl-2,3-dihydro(asym)triazine-3-thione produces a green complex with perrhenate in hydrochloric acid medium in presence of stannous chloride. The complex on extraction in chloroform shows a peak at 685 nm. The system obeys Beer's law from 2–10 p.p.m. of rhenium and its molar absorptivity is 1.53-l0-4. It tolerates the presence of a large number of ions, including MoXXX and WXXX. Job's and molar ratio methods suggest that rhenium and the reagent are present in the ratio 1:2 and the isolated complex is of the same composition, i.e. ReO(C25H10N3S)2. 相似文献
34.
Summary The formation of ternary complexes of the MAL3– type [where M = CuII, NiII and ZnII ; A = nitrilotriacetic acid (NTA); L = 1-hydroxy-2-naphthoic acid (1,2 HNA) and 2-hydroxy-1-naphthoic acid (2,1 HNA)] have been studied potentiometrically in 50% v/v aqueous — ethanol (25° and µ = 0.1). Under identical conditions the binary complexes of the 1,2- and 2,1-HNA ligands have also been examined. The values of mixed ligand formation constants KMAL have been found to be lower than KML (first step formation constant of binary complexes) and even less than
(second step formation constant of binary complexes). 相似文献
35.
Swarup Narain Tewari 《Mikrochimica acta》1967,55(4):704-707
Summary A paper Chromatographic technique on salt-buffered papers for separating the alkaloids of opium has been devised. The method has been used for determining the origin of opium samples by studying the pattern of theR
f
values of the alkaloids present and the effect on it produced by the presence of various adulterants.
Zusammenfassung Die chromatographische Trennung der Opiumalkaloide auf gepuffertem Papier wurde beschrieben. Das Verfahren wurde zur Herkunftsbestimmung von Opiumproben auf Grund desR f -Musters der anwesenden Alkaloide benützt. Der Einfluß verschiedener Fälschungszusätze wurde untersucht.
Résumé Mise au point d'une technique de Chromatographie sur papier pour la séparation des alcaloïdes de l'opium, oú les papiers sont imprégnés des sels tampons. Utilisation de la méthode pour déterminer l'origine des échantillons d'opium en étudiant les valeurs duR f des alcaloïdes présents et l'effet produits sur celles-ci par la présence d'adultérants divers.相似文献
36.
Virendra Singh Anita Rampal S. N. Biswas K. Datta 《Letters in Mathematical Physics》1980,4(2):131-134
The solution of a difference equation in the form of an infinite continued fraction is used to obtain a class of exact solutions for the eigenfunctions and eigenvalues of doubly anharmonic oscillators described by potentials of the type (1/2)2x2+(1/4)x4+(1/6)x6, n>0, provided certain constraints on the couplings are satisfied. The class is denumerably infinite but not complete. 相似文献
37.
M. M. Charyulu K. Venugopal Chetty D. G. Phal Veena Sagar SagarD. M. Sagar S. M. Pawar R. Swarup V. V. Ramakrishna V. Venugopal 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(1):153-154
Recovery of americium from nitric acid solutions was studied by co-precipitation as hydroxide with various ions like calcium, ferric, nickel using sodium hydroxide and ammonium hydroxide. Studies were also carried out to recover americium using lanthanum fluoride and bismuth phosphate co-precipitation. All the methods are able to co-precipitate Am quantitatively. However, co-precipitation of Am with optimum concentration iron using ammonia is found to be better from nitric acid solutions containing large concentrations of calcium ions. Approximately 2 g of Am was recovered from 150 litres of solution batch wise using iron. 相似文献
38.
Datta S Kumar K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(1-3):473-477
The isotropic component of Raman band for C=O stretching mode of acetophenone in solution was analyzed by estimating the correlation coefficient with reference to Lorentzian lineshape. In the intermediate region of solute/solvent concentration there is a sharp decrease in the correlation coefficient and there appears to be a transition from non-Lorentzian to Lorentzian lineshape. The vibrational relaxation rates have been estimated from the isotropic component of Raman band in different solvents. The rate is shown to be dependent on several macroscopic as well as microscopic properties of the solute-solvent system and intermolecular interactions. The hydrodynamic and dispersion forces appear to play a major role in determining the vibrational relaxation rate and the broadening of the bands. 相似文献
39.
The stepwise acid dissociation constants for p-benzohydroquinone (QH2) in aqueous media have been explicitly calculated for the first time, with the INDO parametrized SCF –MO method. We have optimized the geometries of QH2, QH?, and Q2? and of the QH2 · 6H2O, QH? · (H3O+) · 5H2O, and Q2? · (H3O+)2 · 4H2O systems that model the solvated species. The presence of the associated water molecules (and hydronium ions) account for the stabilization due to hydrogen bonding as well as for a part of the effect of interaction of these molecules with the respective reaction fields in an aqueous medium. To simulate the first solvation shell in a more complete manner, four more water molecules have been considered to be placed above and below the quinonoid ring and the optimized geometries of the resulting hydrated species, QH2 · 10H2O, QH? · (H3O+) · 9H2O, and QH? · (H3O+) · 8H2O, have been determined. The standard free-energy changes calculated for the dissociation of QH2 into QH? and H+ is 0.0251 Hartree (65.9 kJ mol?1) and that of QH? into Q2? and H+ is 0.0285 Hartree (74.8 kJ mol?1). Experimentally observed dissociation constants for these two steps correspond to free-energy changes of 0.0214 Hartree (56.2 kJ mol?1) and 0.0248 Hartree (65.1 kJ mol?1), respectively. © 1995 John Wiley & Sons, Inc. 相似文献
40.