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1.
The formation of neutral mixed complexes of the MXmSp type (where M is a metal ion with m+ charge, X the inorganic anion, and S the sulfur-containing extractant) allows a selective extraction of various elements. The extraction of many metals from mineral acid solutions or from halide-sulfuric acid mixtures by 0.05 M O-isopropyl-N-ethylthiocarbamate(IPETC) solution in chloroform has been studied. (IPETC) possesses very high selectivity for silver and mercury ions in extractions from HNO3, H2)SO4, HClO4 and HCl solutions. In addition to silver and mercury, Cu, Au, Tl and Se are readily extracted from solutions containing bromide. From iodide solutions, copper, gold and thallium ions may be selectively extracted because silver and mercury cannot be extracted at concentrations of iodide above 0.1 M.(IPETC extracts metals as mixed complexes, containing the halide and apparently the extractant in the molecular form.  相似文献   

2.
The effect of Cl?, Br?, I?, ClO4?, NO3?, HSO4?, HCrO4? and H2PO4? on the of Al in 2 M HCl is studied by the thermometric method. Three sets of experiments are carried out, which allow the variation of the concentration of the various species in a programmed manner. Dissolution promotion is noted in solutions to which HCl, HBr and H2CrO4 are added. The way of action of each of these anions is discussed. Additions of HI, HClO4, H2SO4 and H3PO4, on the other hand, first retard and later enhance the dissolution of Al in 2 M HCl, as their concentration in solution is increased. This is related to anion adsorption, which is counterbalanced by increase in acidity. HNO3 differs from the other tested acids in causing only dissolution retardation. Experiments in which LaCl3 is added to the test solution indicate that the NO3? is adsorbed as such on Al2O3. The ability of the various anions to retard the dissolution of Al in 2 M HCl decreases in the succession: NO3? (strong)>I?>HSO4?>H2PO4?>Br?, ClO4? (weak)  相似文献   

3.
From the reactions between M2(TiPB)4 compounds and meta and para-vinylbenzoic acids (2 equiv.) in toluene at room temperature the compounds trans-M2(TiPB)2L2, where L = m-vinylbenzoate 1A (M = Mo) and 1B (M = W) and TiPB = 2,4,6-triisopropylbenzoate, and where L = p-vinylbenzoate 2A (M = Mo) and 2B (M = W) have been isolated. Compounds 1A and 2A have been shown to undergo Heck carbon–carbon coupling reactions with phenyliodide to produce trans-Mo2(TiPB)2(O2CC6H4-m-CHCH–C6H5)2, 3A and trans-Mo2(TiPB)2(O2CC6H4-p-CHCH–C6H5)2, 4A. The molybdenum compounds 1A and 2A have been structurally characterized by single crystal X-ray crystallography. All the new compounds have been characterized by 1H NMR, IR, UV-visible absorption and emission spectroscopy, high resolution MALDI-TOF MS, fs- and ns-transient absorption spectroscopy and fs-time-resolved IR spectroscopy. Electronic structure calculations employing density functional theory, DFT, and time-dependent DFT have been employed to aid in the interpretation of spectral data. All compounds show intense absorptions in the visible region corresponding to M2δ to Lπ* charge transfer transitions. The lifetimes of the 1MLCT state fall in the range of 1–10 ps and for the molybdenum complexes the T1 states are 3δδ* with lifetimes ∼50 μs while for the tungsten complexes the T1 are 3MLCT with lifetimes in the range of 3–10 ns.  相似文献   

4.
Methods for determining chromium in high-alloy steels based on potentiometric titration after oxidation of chromium(III) to chromium(VI) with peroxodisulphate were studied using different dissolution procedures, viz., dissolution in HClHNO3 and fuming with H2SO4H3PO4, dissolution in HClHNO3 and fuming with HClO4, dissolution in HClHNO3HF in a microwave oven, fusion in sodium peroxide in a zirconium crucible and dissolution in dilute H2SO4 and oxidation with H2O2. A back-titration was used with dichromate after addition of solid ammonium iron (II) sulphate.The dissolution procedures were tested on 24 certified reference materials (0.01–3.3% C, 10–325% Cr). All procedures except the second gave good results for samples with ? 0.8% C. For samples with ? 0.8% C, the third and fourth procedures gave significantly higher values and better precisions, and gave the best results for all samples. The relative standard deviations were, with few exceptions, below 0.2%.  相似文献   

5.
The chemical and electrochemical properties of technetium metal were studied in 1–6 M HX and in 1 M NaX (pH 1 and 2.5), X = Cl, NO3. The chemical dissolution rates of Tc metal were higher in HNO3 than in HCl (i.e. 8.63 × 10?5 mol cm?2 h?1 in 6 M HNO3 versus 2.05 × 10?9 mol cm?2 h?1 in 6 M HCl). The electrochemical dissolution rates in HNO3 and HCl were similar and mainly depended on the electrochemical potential and the acid concentration. The optimum dissolution of Tc metal was obtained in 1 M HNO3 at 1 V/AgAgCl (1.70 × 10?3 mol cm?2 h?1). The dissolution potentials of Tc metal in nitric acid were in the range of 0.596–0.832 V/AgAgCl. Comparison of Tc behavior with Mo and Ru indicated that in HNO3, the dissolution rate followed the order: Mo > Tc > Ru, and for dissolution potential the order: E diss(Ru) > E diss(Tc) > E diss(Mo). The corrosion products of Tc metal were analyzed in HCl solution by UV–Visible spectroscopy and showed the presence of TcO4 ?. The surface of the electrode was characterized by microscopic techniques; it indicated that Tc metal preferentially corroded at the scratches formed during the polishing and no oxide layer was observed.  相似文献   

6.
1,2,3,4-Tetrazine 1,3-dioxides annulated with 1,2,3-triazoles and 1,2,3-triazole 1-oxides have been synthesized by the reaction of 4-amino-5-(tert-butyl-NNO-azoxy)-2-R-2H-1,2,3-triazoles (R=Me, i-Pr, t-Bu) and their 1-oxides (R=H, Me, Et, i-Pr) with the HNO3/H2SO4/Ac2O system. Their thermal stability, spectroscopic, and X-ray properties have been studied.  相似文献   

7.
The title method was successfully used for collecting239,249Pu from 200 litres of seawater by coprecipitation with 16 g FeSO4·7H2O under redcing conditions witout filtering. The plutonium is leached by concentrate HNO3+HCl from the coprecipitate and the solid particles. The precipitate is heated at 400°C and digested in aqua regia. Na2SO3 and NaNO2 have been applied to obtain the Pu4+ valence state in 0.5–1N HNO3 for different samples. Plutonium and thorium are coadsorbed on anionic resin from 8N HNO3. The column is eluted with 8N HNO3 containing fresh NaNO2 to keep the Pu4+ state for uranium decontaination. The system of the column is changed from 8N HNO3 to concentrated HCl with 50 ml concentrated HCl containing a few milligrams of NaNO2. Furtheer decontaimination of torium was achieved by elution with concentrated HCl instead of 9N HCl. The plutonium is successfully stripped by H2O, NaOH, 2N HNO3 and 0.5N HNO3 containign 0.01M NaNO3. The chemica yield of plutonium for a 2001 seawate sample is 60–80%. The resolution of the electroplated thin source is very good.  相似文献   

8.
Preparation und Characterization of Phthalocyanine-π-Cation-Radicals of H+, Mg2+, and Cu2+ The preparation of phthalocyanine-π-cation-radicals (Pc(?1)) of H+, Mg2+, Cu2+ is described. MgClPc(?1) and Cu(NO3)Pc(?1) · HNO3 are isolated as stoichiometrically pure, stable redbrown solids. Contrary to the phthalocyanines(?2) (Pc(?2)) these are very soluble with redviolet colour in organic solvents in the presence of R? COOH (R ? H, CF3, CCl3). The electronic absorption absorption spectra (UV-VIS) are remarkably solvent-dependent. This solvent effect is due to a reversible radical association. Monomeric radical species exist in nonpolar (CH2Cl2), dimeric in polar solvents (CH3NO2, C2H5OH). The UV-VIS, infrared (IR), and resonance-raman (RR) spectra of MgClPc(?1) and Cu(NO3)Pc(?1) · HNO3 are discussed and compared with the analogoues spectra of MgPc(?2) · 2 H2O and MgPc(?2) · HCl. Although there are only minor differences in the chemical composition and the electronic structure the spectroscopic data vary significantly for every complex. Especially the IR spectrum is suitable for a quick demonstration of the π-cation-radicals. The diagnostic bands are at ca. 1350 and 1450 cm?1.  相似文献   

9.
The heat of immersion in water was measured at 25°C for three iron(III) oxides using a twin-type microcalorimeter. One of the samples was commercial α-Fe2O3 (sample C) and the other two (samples M and F) were prepared by calcining magnetite and iron(III) hydroxide in air at various temperatures, Tp, from 300 to 700°C. The samples were evacuated at outgassing temperature, To, between room temperature and 500°C at a pressure of 1 × 10?2?2.7 × 10?2N m?2 for 6 h. The heat of immersion, hi(J m?2), of samples C and M increased with an increase in To and showed the maximum hi at To =400°C, while sample F did not show the maximum up to To =500°C. The systematic correlation was not observed between hi and Tp of sample F. The heat of reproduction of the surface hydroxyl group on sample F was approximately estimated as 6.6 × 104 J mole?1 H2O.  相似文献   

10.
A technique was developed for the dissolution of Al-Fe materials containing difficult to dissolve Al2O3. The developed procedure uses HCl and HNO3 for initial sample attack followed by digestion with a mixture of H3PO4 and H2SO4 at 200?°C. This procedure was employe to dissolve Al-Fe material samples before the determination of Al and Fe. Minor and trace elements (B, Cr, Cu, Mo, Si, Zr) were determined after dissolution in HCl and HNO3. Results of a round robin study verified the procedure accuracy. The developed methods have the required accuracy and precision to be used as a quality control procedure for Al-Fe materials analysis.  相似文献   

11.
The synthesis, structures, and magnetochemical data for the heterospin chain polymer complexes Cu(hfac)2LAll and Cu(hfac)2LBu·0.5Solv, where hfac is the hexafluoroacetylacetonate anion, LAll and LBu are 2-(1-allyl-1H-pyrazol-4-yl)- and 2-(1-butyl-1H-pyrazol-4-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyls, respectively, Solv is isopropylbenzene or tert-butylbenzene, were described. These polycrystalline solids were found to exhibit similar magnetic anomalies. Thus, the effective magnetic moment first decreases and then increases with temperature, resulting in the specific minimum in the curve μeff(T). The study of the magneto-structural correlations showed that the appearance of the minimum is attributed to different factors. For Cu(hfac)2LAll, this is the phase transition accompanied by the structural rearrangement of the exchange cluster >N—·O—CuII—O·—N<, which leads to a change in the energy of the exchange interaction between the unpaired electrons of the paramagnetic centers. By contrast, for Cu(hfac)2LBu·0.5PriPh and Cu(hfac)2LBu·0.5ButPh, the appearance of the minimum is a consequence of the coexistence of exchange interaction energies with opposite signs, while the structure of the solid phase remains unchanged.  相似文献   

12.
Phosphane, Phosphite, Phosphido, Complexes of Vanadium(V) Complex formation of tert-butylimidovanadium(V)trichloride ( 1 ) with phosphanes und phosphites has been studied. Syntheses of phosphidovanadium(V) compounds tC4H9N?VCp(NHtC4H9)[P(SiMe3)2] and tC4H9N?VCp(NiProp2)(PR2) (R?SiMe3, Ph) are described starting from the corresponding chlorovanadium(V) complexes. The reaction of 1 with silver hexafluorophosphate yields a bis(fluoro)phosphidovanadium(IV complex [(μ-PF2)2V2Cl2)(NtC4H9)2]; as primary intermediate product of the unknown redox reaction a cationic vanadium(V) complex [tC4H9N?VCl2 · PPh3]+PF6? has been isolated. 1 reacts with an excess of diisopropylamine forming tC4H9N?V(NiProp2)Cl2 ( 16 ); in addition the following diisopropylamido-tert-butylimidovanadium(V) compounds tC4H9N?VCp(NiProp2)Cl ( 3 ) and tC4H9N?V(NiProp2)X2 (X?CH2CMe3, OtC4H9, CH3COO) has been prepared. All compounds obtained are characterized by 1H, 51V, 31P NMR spectroscopy. The X-ray diffraction analysis of 16 and 3 indicate a planar coordination sphere of the amido nitrogen atom.  相似文献   

13.
The reactions of RCo(BDM1,3pn)(H2O) with light, heat, acids, electrophiles and nucleophiles were studied. (HBDM1,3pn is a mononegative, tetradentate dioxime-diimine ligand formed by condensing 2,3-butanedionemonoxime with 1,3-propanediamine in a 2/1 molar ratio; R = CH3, C2H5, n-C3H7, n-C4H9, and C6H3CH2-) Pyrolysis and photolysis of the alkyl complexes result in a cobalt(II) complex (anaerobic conditions) along with alkenes and alkanes. The major organic products from solid state pyrolysis at 200°C or photolysis in water are CH4 (R = CH3), C2H4 (R = C2H5), C3H6 (R = n-C3H7), C4H8 (R = n-C4H9) and (C6H5CH2)2 (R = C6H5CH2). No alkyl—cobalt bond cleavage occurs with acids or bases in most cases. Two exceptions are the reactions with 3 M HNO3 at 25°C and with 1 M NaOH at 52°C. Electrophiles like I2 cleave the alkyl—cobalt bond forming RI and CoIII (BDM1,3pn)I2. Nucleophilic reagents (N-) displace the H2O trans to the alkyl group to form RCo(BDM1,3pn)(N), but do not dealkylate the alkyl complex under the reaction conditions studied.  相似文献   

14.
A technique was developed for the dissolution of Al-Fe materials containing difficult to dissolve Al2O3. The developed procedure uses HCl and HNO3 for initial sample attack followed by digestion with a mixture of H3PO4 and H2SO4 at 200 °C. This procedure was employe to dissolve Al-Fe material samples before the determination of Al and Fe. Minor and trace elements (B, Cr, Cu, Mo, Si, Zr) were determined after dissolution in HCl and HNO3. Results of a round robin study verified the procedure accuracy. The developed methods have the required accuracy and precision to be used as a quality control procedure for Al-Fe materials analysis. Received: 9 February 1998 / Revised: 1 April 1998 / Accepted: 4 April 1998  相似文献   

15.
Collinear collisions on the H3+ potential energy surface for different mass combinations m, M, m are investigated by means of classical trajectory computations. Both, the probability for reaction, Pt, and for complex formation, Pe, depend periodically on the mass parameter (1 + 2m/M)12. This can easily be understood in terms of vibrational excitation of the symmetric and asymmetric modes of the reaction complex. If the collinear constraint is lifted, none of these features survive.  相似文献   

16.
Different methods for the determination of several metals in soils by flame atomic absorption spectrometry (FAAS) were investigated. Different procedures for total dissolution of soil: I – HF+HClO4, H3BO3, HCl digestion (conventional heating), II – HF+HClO4, H3BO3 digestion followed by fusion with LiBO2 (conventional heating) and III – HF+HCl+HNO3, H3BO3 digestion (microwave heating), as well as a leaching procedure with HNO3+HClO4, HCl were tested and compared. For quality assessment, the certified reference material S-1 soil was used. For most of the investigated metals, the best accuracy and precision were achieved when the procedure I or III were used. The developed procedure was applied to the analysis of soil samples from crude oil refinery and dump of petroleum origin wastes regions.  相似文献   

17.
《Polyhedron》1987,6(6):1375-1381
N-nitroso-N-alkylhydroxylamines have been prepared by hydrolysis of the mixture obtained by reaction of nitric oxide with Grignard reagents, and stabilized as their copper(II) or iron(III) complexes, Cu(RN2O2)2 and Fe(RN2O2)3, where R is, for example, Me, Et, Pri, Buiso, Ph, n-C8H17 or n-C12H25. The complexes have been characterized by analytical, magnetic and spectroscopic measurements. By single-crystal X-ray methods Cu(PriN2O2)2 has been found to be trans-planar and Fe(PrnN2O2)3 has a facial octahedral structure; in each complex the NO bond lengths are equal with no significant variation between the copper and iron complexes.  相似文献   

18.
Abstract

The aim of this study was to assess the performance of selected destruction methods for the determination of heavy metals (Cd, Cu, Pb and Zn) in woodlouse (Oniscus asellus). A vigorous total analysis involving microwave destruction with HF, HCl and HNO3 (method 1) was used as a reference method. Consistently low values for the dry ashing method may indicate incomplete dissolution of the elements and/or losses through volatilisation. Method 3 (concentrated HNO3) that frequently is used in literature, produced erroneous values for Cd, Cu and Pb. Results were consistent with the microwave digestion, provided H2O2 was used during digestion (method 4, HNO3/H2O2). Method 5 (HNO3/HCIO4, one destruction step) yielded low recoveries when only one destruction step was applied. Applying two destruction steps (method 6) resulted in values consistent with the microwave method, but was at the expense of reproducibility and rendered the method more lengthy and laborious. Because of the very good performance combined with speed and simplicity, destruction with HNO3/H2O2 (method 4) emerged as the most convenient method.  相似文献   

19.
The ring-opening Si-fluorination of a variety of azasilole derivatives cyclo-1-(iPr2Si)−4-X−C6H3−2-CH2NR ( 4 : R=2,6-iPr2C6H3, X=H; 4 a : R=2,4,6-Me3C6H2, X=H; 9 : R=2,6-iPr2C6H3, X=tBuMe2SiO; 10 : R=2,6-iPr2C6H3, X=OH; 13 : R=2,6-iPr2C6H3, X=HCCCH2O; 22 : R=2,6-iPr2C6H3, X=tBuMe2SiCH2O) with different 19F-fluoride sources was studied, optimized and the experience gained was used in a translational approach to create a straightforward 18F-labelling protocol for the azasilole derivatives [18F] 6 and [18F] 14 . The latter constitutes a potential clickable CycloSiFA prosthetic group which might be used in PET tracer development using Cu-catalysed triazole formation. Based on our findings, CycloSiFA has the potential to become a new entry into non-canonical labelling methodologies for radioactive PET tracer development.  相似文献   

20.
Dissolution of zinc and nickel ferrites were previously found2,3 to conform to the equations: $$\frac{{dx}}{{dt}} = ks_0 \left( {1 - x} \right)^3 K = \frac{1}{t}\left[ {\frac{1}{{\left( {1 - x} \right)^2 }} - 1} \right]$$ x-solubility (%),t=time (min),s 0=initial specific surface (m 2·g?1),k-rate constant independent of specific surface,K=apparent rate constant dependent on specific surface (min?1). The aim of this work was to check the applicability of these equations to the dissolution of nickel—zinc ferrites. The experimental results obtained for 3 mixed ferrites (Ni0.3Zn0.7Fe2O4, Ni0.5Zn0.5Fe2O4, Ni0.7Zn0.3Fe2O4) revealed that kinetics of their dissolution in HCl, HNO3 and their mixtures also conform to the equations stated above.  相似文献   

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