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31.
Ashok K. Singh Alka Srivastava Ashutosh Kumar Bharat Singh 《Transition Metal Chemistry》1993,18(4):427-430
Summary The kinetics of iridium(III)-catalysed oxidation of 1,2-ethanediol and 1,4-butanediol by N-bromoacetamide (NBA) in HClO4 in the presence of [Hg(OAc)2] as a scavenger for Br– have been investigated. The reactions are zero-order with respect to both diols, and first-order in NBA at low NBA concentrations, tending to zero order at high concentrations. The order in IrIII decreases from unity to zero at high iridium(III) concentrations. A positive effect on the oxidation rate is observed for [H+] and [HgII] whereas a negative effect is observed for acetamide and [Cl–]. Ionic strength does not influence the oxidation rate. (H2OBr)+ is postulated as the oxidizing species. A mechanism consistent with the observed kinetic data is proposed. 相似文献
32.
R. Garg V. K. Garg I. Czakó-Nagy S. Nagy E. Kuzmann A. Vértes 《Journal of Radioanalytical and Nuclear Chemistry》1994,186(6):455-462
Mössbauer spectroscopy and X-ray diffractometry have been used to study Sm–Fe mixed oxides (with different SmFe atomic ratios) annealed at 550, 850, 1000 and 1250 °C. The room temperature Mössbauer spectra can be interpreted in terms of one, two or three sextets and in some cases by an additional doublet depending on the composition and the heat treatment. The sextets have been associated with SmFeO3 perovskite, Sm3Fe5O12 garnet and -Fe2O3 hematite. These results are in agreement with those of X-ray diffractometric measurements, which give a clear, evidence of the presence of these phases. 相似文献
33.
D. L. Samudralwar R. B. Lanjewar A. N. Garg 《Journal of Radioanalytical and Nuclear Chemistry》1987,119(3):211-221
A radiochemical solvent extraction method has been developed for the micro determination of Mo/VI/ using99Mo tracer. It involves removal of99mTc by ethyl methyl ketone /EMK/ and extraction of Mo with tri-n-butyl phosphate /TBP/ from 5M HCl. Different parameters affecting the extraction such as pH dependence, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 2 g of Mo. 相似文献
34.
A series of fifteen complexes of the type [Fe(RRNCS2)3] with symmetric (R=R=n- C6H13, n-C8H17, CH2–CH=;CH2, C6H5, C6H11 and C6H5CH2), unsymmetric (R = CH3; R = n-C4H9, C6H11, C6H5 and R = C2H5; R = n-C4H9, C6H11, C6H5 and i-C3H7) and ring substituents (RNR=pyrrolidyl and piperidyl) have been synthesized and their magnetic moments and Mössbauer spectra recorded from room temperature (RT) to liquid nitrogen temperature (LNT). Room temperature Mössbauer spectra of all the complexes exhibit an asymmetric doublet, which could be resolved into two doublets, each corresponding to low and high spin states in equilibrium. The crystal structure of tris(N, N-diallyldithiocarbamato)iron(III) shows it to be monoclinic with trigonally distorted octahedral geometry and space group C2/c. Fe–S stretching vibrations in the far i.r. region also show equilibria, HS LS. Depending on the nature of the alkyl group substituent, variable temperature magnetic moment and Mössbauer spectral studies, all the complexes may be divided into three groups; high spin complexes exhibiting spin-crossover (6A1g 2T2g), high spin complexes exhibiting spin transition (6A1g 4T1g) and intermediate spin complexes showing spin transition (4A1g 2T2g). On the basis of areas of the two doublets corresponding to high and low spin states, their percent contributions were calculated. Furthermore, magnetic moments of the equilibrium mixture calculated on the basis of respective areas compare well with the experimentally determined eff values. EQ values for both high and low spin states show linear decrease with increasing temperature. 相似文献
35.
Different molar reactions of Fe(OPr1)3, and FeCl3 with benzothiazolines having an NSH donor system. derived by the condensation ofo-aminothiophenol with heterocyclic aldehydes. viz. pyridine-2-aldehyde. furfuraldehyde and thiophene-2-aldehyde. lead to the
formation of [Fe.Pr1(NS)2]2, [Fc(NS)3] and [Fe(NS)2Cl| type of complexes. The resulting derivatives have been characterized by elemental analysis, conductivity measurements,
molecular weight determinations and magnetic studies. IR, electronic, M?ssbauer and ESR spectral data have been used to deduce
the structures of the resulting derivatives. 相似文献
36.
A new solid analytical reagent is reported for the detection and semiquantitative determination of traces of fluoride. A blue (λmax 590 nm) trypan blue dye is liberated from an insoluble zirconium-trypan blue complex by the action of fluoride in dilute acetic acid medium. The detection limit is 0.8 ppm and the range of semiquantitative determination is 0.8 to 8 ppm. The method is simple and can be conveniently used for field detection of fluoride in polluted waters. 相似文献
37.
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39.
Complexes of CoII with N,N-bis-(3-carboxy-1-oxopropanyl)-1,2-ethylenediamine(L1), N,N-bis-(3-carboxy-1-oxopropanyl)-1,2-phenylenediamine(L2), N,N-bis-(2-carboxy-1-oxophenelenyl)-1,2-phenylenediamine(L3) and N,N-bis-(3-carboxy-1-oxoprop-2-enyl)-1,2-phenylenediamine(L4) have been prepared and characterized by elemental analysis, vibrational spectra, magnetic susceptibility measurements, electronic spectra and thermal studies. Stability constants of the complexes have been evaluated potentiometrically. Vibrational spectra indicate coordination of amide and carboxylate oxygens of the ligands along with two water molecules giving a MO6 weak field octahedral chromophore. Electronic spectra support octahedral geometry around CoII. The [Co(L1)-(H2O)2] · 2H2O complex has the maximum activation energy and [Co(L3)(H2O)2] complex has the minimum activation energy. The order of stability constants of the CoII complexes with various ligands is due to their -donor abilities. 相似文献
40.
Vineet Aniya Alka Kumari Rupesh Reddy B. Satyavathi 《Journal of solution chemistry》2017,46(6):1177-1201
2-Methylpropan-2-ol, an important fine chemical, may be dehydrated during extractive distillation with glycols as entrainer. Experimental isobaric phase equilibrium studies were carried out on binary mixtures of 2-methylpropan-2-ol with ethane-1,2-diol, as an entrainer, at the local atmospheric pressure of 94.99 kPa and at sub-atmospheric pressures of 19.99, 39.99, 59.99, 78.79 kPa using a Sweitoslawski-type ebulliometer. The Wilson and NRTL activity coefficient models were used to correlate the experimental results and the binary interaction parameters were obtained using the Generalized Reduced Gradient optimization technique. UNIFAC was also used to predict the deviations in bubble temperatures. Moreover, the variation in density, refractive index values and other derived properties (excess molar volumes, partial molar volumes and deviations in molar refractivity) were explored at 303.15, 313.15, 323.15 and 333.15 K to understand the shift of equilibrium with the variation in the mixture composition for the conformational state of the molecules. The Redlich–Kister polynomial equation was used to correlate the excess molar volumes and deviations from molar refractivity. Different theoretical mixing rules (Lorentz–Lorenz, Wiener, Heller, Gladstone–Dale and Arago–Biot) are investigated and reported in terms of average percentage deviation. Furthermore, the Prigogine–Flory–Patterson theory was used to predict the trend of the dependence of excess molar volumes on composition for the present system. 相似文献