Summary The diffusion of tartrate complexes of Cu2+, Co2+, Ni2+ and Cd2+ through filter paper strips has been examined using 50% and 60% ethanol as solvents. The Rf values are higher when 50% ethanol is used. When 50% ethanol is used, it is noted in the case of Cu2+, Co2+ and Ni2+ that the Rf values decrease with the addition of tartrate in the beginning. Then the value increases and finally becomes constant. In case of Cd2+ the Rf value decreases by the addition of tartrate. In 60% ethanol the Rf value does not change by small additions of tartrate but decreases with higher concentration of the complexing agent. In case of Cd2+ the Rf value becomes zero by increasing the concentration of tartrate.Part I: See Z. analyt. Chem. 159, 332 (1957/58). 相似文献
Summary The movement of metal ammines through filter paper strips has been studied. Mixtures of solutions of the metal salts with NH4Cl and NH4OH were prepared and spotted on strips. 50% ethanol was used as the solvent. It was noted that excess of NH4Cl when present, gave better chromatograms. Increase of NH3 concentration resulted in a change of Rf values. In the case of CuII and NiII the Rf value decreases, while in the case of AgI, CdII and CoII it increases with increasing concentrations of NH4OH added. With progressive increase in the concentration of NH4OH the Rf values finally tend to become constant. 相似文献
Abstract The adsorption behaviour of 48 metal ions has been studied in Oxalic acid - Oxalate systems using silica gel - G layers. The effect of pH on Rf values was also investigated. A plot of -log Ksp Vs. RM and Rf shows the dramatic behaviour of Hg2+ ion in 0.1 M Potassium Oxalate + 0.1 M Ammonium Oxalate (1:1) system. A number of interesting separations have been achieved e.g., Fe3+ - Ti4+ zr4+ - Ti4+, ce4+ - La3+, zr4+ - Th4+, Te4+ - Se4+ and Zr4+ - Y3+ - La3+. Ti4+ and Nb5+ were separated from a mixture of number of ions. 相似文献
Abstract The adsorption behaviour of 47 metal ions has been studied in aqueous HCl systems using stannic ersenate layers. The effect of solvent pH on Rf alongwith the complexation effect of HCl has been investigated. On the basis of Rf values the KSP of some metel arsenates have been predicted. HCl has been utilized to resolve some binary and ternary mixtures such as Be2+ - Mg2+, Zr4+ - La3+, Th4+ - Ce4+, Th4+ - UO2+2, Cr3+ - Mo6+ or W6+, Sb3+ - Bi3+ - Cd2+ and Ag+ - Cu2+ - Cd2+. 相似文献
Summary The chromatographic behaviour of 49 metal ions has been studied on papers impregnated with Sn(IV) and Ti(IV) antimonates in aqueous HNO3 and mixed solvent systems containing dimethyl sulphoxide. Numerous separations have been achieved and the Alberti equation, for Sn(IV) and Ti(IV) antimonate papers, in the modified form: –nloga K+=RM + constant (a K+=activity of K+), has been verified. The effect of the concentration of impregnating reagents on these papers has been determined and compared with other papers. The effect of pH on Rf, Ri, log Rf and RM values of metal ions has also been examined in aqueous systems. 相似文献
This paper describes the application of thin-layer chromatography (TLC) combined with densitometry to simultaneous determination of levofloxacin hemihydrate (LEV) and ambroxol hydrochloride (AMB) in bulk and tablets. The separation was achieved on aluminum sheet of silica gel 60 F254 using chloroform: methanol: toluene: ammonia (10: 6: 3: 0.8 v/v/v/v) as mobile phase. Quantification was carried out densitometrically
at 245 nm. This system was found to give compact spots for LEV (Rf value of 0.4) and AMB (Rf value of 0.7). The calibration curves for LEV and AMB was found to be linear between 9960–16600 ng/spot (r2 = 0.999) and 600–1000 ng/spot (r2 = 0.999), respectively. The mean percentage recoveries from tablets for LEV and AMB were 99.45% and 99.58%, respectively.
The TLC-densitometry method has many advantages, such as simplicity, reasonable sensitivity, rapidity, and low cost, and it
can be successfully used in routine analysis of both these drugs in tablet formulations. 相似文献
Abstract Chelation ion chromatography of metal ions on DMSO impregnated silica gel-G layers in ether; DMSO: 1M HNO3 (1:1); n-butanol: acetone: HNO3 (6:6:1) and di-isopropyl ether: DMSO: THF systems having varying compositions, was performed. The zero Rf for a number of cations is explained in terms of precipitation and strong adsorption. It was possible to separate Cd2+, W6+, Zr4+, Zn2+ and VO2+ from numerous metal ions. A number of analytically important binary and ternary separations were also achieved and were found useful in synthetic alloy analysis. 相似文献
Uncompensated resistance (Ru) has a distoring effect on normalized potential sweep voltammetry (NPSV) slopes. This provides a simple and effective method to determine Rfo, the value of the potentiostat feedback resistance necessary for full compensation. If the NPSV range is divided into overlapping segment, 1 and 2, corresponding to IN of 0.20–0.50 and 0.50–0.80 respectively, the slopes m1 and m2 differ significantly when Rf differs form Rfo. The difference, m1-m2, is negative for Rf<Rfo and positive for Rf>Rfo. Fine tuning of the potentiostat Rf setting so that the average value of the difference is the theoretical value can be accomplished in a minimum of time. Under these conditions, m1 and m2, as well as mT, the slope of the entire correlation have very nearly the same values. Linear equations were derived from theoretical data which allow heterogeneous rate constants to be obtained directly from NPSV slopes. The precision in the NPSV slopes was observed to be of the order of ±0.002 which implies that the method should give reliable rate constants as great as 10cm s? at a voltage sweep rate of 100V s?1. The method is demonstrated using the reduction of benzonitrile and perylene in N,N-dimethylformamide and acetonitrile as examples. 相似文献
A series of new polyfluorinated dienes 3, containing the novel -CFCHCHCF-, pattern has been synthesized (50–70% yields) by reacting perfluoroalkyl iodides with perfluoroalkyl-ethylenes in the presence of copper. The monoalkenes RfCFCHCH2CF2R′f and the saturated compounds RfCF2CH2CH2CF2R′f were obtained by varying the experimental conditions. The 1H and 19F NMR spectra are analysed and the reaction mechanism is discussed. 相似文献
Summary The kinetics of formation of the NiII and CoII complexes of pyridine 2-azo-p-dimethylaniline have been studied in aqueous ethylene glycol, aqueous glycerol and in moderate (up to 2.5 mol dm–3) concentrations of NaCl at 298.2K.Mole fractions of 0.24 and 0.12 respectively for ethylene glycol and glycerol effect a lowering of the formation rate constant Kf of Ni(PADA)2+ to about 50% of the value in water. A concentration of 2.0 mol dm–3 NaCl doubles kf for both the Ni and Co complexes. These findings are discussed within the framework of the dissociative interchange mechanism; the possible effects upon each step of the mechanistic pathway are considered. 相似文献
The title compound1 was resolved into enantiomers by medium-pressure liquid chromatography on microcrystalline triacetylcellulose in ethanol. After four cycles pure enantiomers were obtained ([]
D20
+ and — 330°, resp., in ethanol) and their circular dichroism spectra recorded. From optical comparison with structurally related thujane derivatives and by applying the octant rule, for (—)-1 the chirality (7R, 9R) was deduced. 相似文献
Zusammenfassung Der Einfluß organischer Wasserinhaltsstoffe (z. B. Huminsäure, Ligninsulfonsäure, Acetat, Citrat, EDTE) auf analytische Multielement-Anreicherungen (Cu2+, Fe3+, Mn2+, Pb2+ und Zn2+) an einem Chelat-Ionenaustauscher (Cellulose-Hyphan) wird beschrieben. Erwartungsgemäß verursacht der starke Chelatbildner EDTE erhebliche Störungen. Bereits mg/l-Konzentrationen an EDTE senken die analytische Spurenwiederfindung auf 0 (Pb2+) bis 50% (Mn2+). Durch eine oxidierende UV-Photolyse (Hg-Niederdruck-Strahler, 70 W, 1 h bei 45° C) lassen sich die störenden Wasserinhaltsstoffe (<200 mg/l) einfach und schnell aufschließen. Der UV-Aufschluß wird in seiner Abhängigkeit von Zeit, Oxidationsmittel (H2O2) sowie von organischen bzw. anorganischen Matrices (Ethanol bzw. NaCl) untersucht. Er zeichnet sich im Spurenbereich (je 20 g/l Cd2+, Cu2+, Fe3+, Mn2+, Ni2+, Pb2+, Zn2+) durch gute Reproduzierbarkeit und niedrige Blindwerte (z. B. Fe, Zn<1 g/l) aus. Die Elemente werden mit der Flammen-AAS bestimmt.
UV-photolysis of dissolved organic matter as sample pretreatment for the analytical multielement-enrichment, especially on chelating ion-exchangers
Summary The influence of water-dissolved organic matter (e.g. humic acid, lignin sulphonic acid, acetate, citrate, EDTE) on the analytical multielement-enrichment (e.g. Cu2+, Fe3+, Mn2+, Pb2+, Zn2+) on a chelating ion-exchanger (Cellulose-Hyphan) is described. As expected, the strong chelating agent EDTE causes large interferences. Thus, mg/l-concentrations of EDTE lower the analytical recovery rate to values between 0 (Pb2+) and 50% (Mn2+). In a fast and simple manner, the interfering organic matters in waters (<200 mg/l) can be eliminated by an oxidizing UV-irradiation (Hg-low-pressure lamp, 70 W, 1 h at 45° C). This UV-photolysis is investigated as function of the time, the oxidant (H2O2) and organic resp. inorganic matrices (ethanol resp. NaCl). At the trace level (20 g/l Cd2+, Cu2+, Fe3+, Mn2+, Ni2+, Pb2+, Zn2+, each) it shows a good reproducibility and low blank values (e.g. Fe, Zn<1 g/l). The elements are determined by flame-AAS.
Herrn Prof. Dr. H. Weisz zum 60. Geburtstag gewidmet 相似文献
Simple expressions are derived for the development of monomer conversion, as well as propagating radical, adduct radical, dormant chain, and dead chain concentrations in reverse addition‐fragmentation transfer polymerization (RAFT). The relations for the profiles of propagating radical concentration and conversion versus time are derived and depend on group parameters of rate constants and chemical recipe. The analytical equations are verified against numerical solutions of the mass‐balance differential equations. This derivation involves the steady‐state hypothesis for radical and RAFT agent concentrations. The errors introduced by these assumptions are negligible when the fragmentation rate constant, kf, is higher than 10 s−1 or when the cross‐termination rate constant, kct, is higher than 105 L · mol−1 s−1.
Calculated concentration profiles (points: numerical, lines: analytical) of propagating radical R, adduct radical A, dormant T, and dead D (= P + P′) chains. 相似文献
The graft copolymerization of methyl methacrylate onto poly-(ethylene terephthalate) using metal complexes of Mn3+, Co3+, and Fe3+ as initiators was studied. The rate of polymerization, Rp, increased with increasing complex concentrations. The rate of polymerization was also studied by varying monomer concentrations. Increasing monomer concentrations, the rate of polymerization increases significantly. The graft yield increases with increasing temperature within the range 60–75°C. The graft yield is medium dependent. A suitable kinetic scheme has been pictured and rate equations have been derived. 相似文献
Reactions of the fluorinated amines (CF3)2NH, CF3N(OCF3)H, CF3N[OCF(CF3)2]H, CF3NHF and SF5NHF with the strong acid HF/AsF5 form the corresponding ammonium salts Rf1Rf2NH2+AsF6? and RfNFH2+ AsF6? in high yield. [Rf1=CF3, Rf2=CF3, CF3O, (CF3)2CFO; Rf=CF3, SF5] The colorless crystalline solids are stable for prolonged periods at 22°C in sealed FEP containers. They have dissociation pressures at 22°C ranging from ~5 torr (RfNFH2+ AsF6?) to ~50 torr [CF3N(OCF3)H2+AsF6?]. 19F NMR and Raman spectroscopy were used to identify the compounds. 相似文献
The solvation number and hydration constant of Th4+ in ethanol-water medium were determined at 25°C using UV-spectral and electrochemical measurements. A solvate formation equilibrium is demonstrated and characterized. Three molecules of ethanol (S) can bond to the metal cation with strengths comparable to that for H2O to form ThS3(H2O)34+ Formation of thorium monochelate with lawsone (2-hydroxy-1,4-naphthoquinone) eliminates bonding with alcohol molecules. The dissociation constant of the chelating agentsKa and the formation contant of the monochelated metal ionsKf* that are essentially independent of the solution composition are evaluated. Hydration titrations involving thorium-lawsone monochelate are performed and the data obtained from the changes of pH with solvent composition are analyzed. The solution independent constant,sKf* for thorium-lawsone complex formation in mixed aqueous ethanol is given by $$log_s K_f * = vpK_a + log_s K_h - log[LH] - vpH + 3logv$$ where vpKa is the dissociation constant of the chelating agent LH in the solvent system of ν volume fraction of water andsKh is the solution-independent hydration constant of thorium (IV) in the solvent system. Log-values for the constantssKh,sKf* andsKa* are found to be 7.8±0.02, 11.38±0.04 and ?0.753, respectively. 相似文献
In reactions with perfluoroalkylsulfenyl chlorides (RfSCl; Rf = F3, C2F5, n-C3F7, n-C4F9) and perfluoroalkyl disulfides (RfSSRf′; Rf = Rf′ = CF3, Rf = CF3, Rf′ = C2F5) at 25°, chlorine monofluoride acts primarily as a chlorinating and fluorinating reagent to give the corresponding perfluoroalkylsulfur chloride tetrafluorides, RfSF4Cl, in good yields. However, small amounts of perfluoroalkylsulfur pentafluorides, RfSF5, are also obtained. A mixture of the cis and trans isomers of bis(trifluoromethyl)sulfur tetrafluoride and of trifluoromethyl pentafluoroethylsulfur tetrafluoride has been formed by the reaction of the corresponding bis(perfluoroalkyl) sulfides and chlorine monofluoride. The new perfluoroalkylsulfur chloride tetrafluorides are colorless, unpleasant smelling liquids. The infrared, mass and 19F NMR spectral data, as well as thermodynamic and elementary analysis data, are given for the new compounds. 相似文献
Abstract Duet to the key role of arylazopyrazoles in biochemical sciences, interest has sprung up to achieve their resolution and identification by thin layer chromatographic technique. Present communication describes the resolution of some N-carbamoyl-3, 5-dimethyl-4-arylazopyrazoles on silica gel-G plates impregnated with various surfactants viz., 1% acetoacetanilide, 1% tritonX-100 and 1% tetrabutylammounium bromide. A correlation of Rf value with Hammett substituent constant (σ) is also interpreted. 相似文献
Abstract Selective C-6 hydroxyl triphenylmethylation of methyl 2,3-O-isopropylidene-α-D-mannofuranose (1), followed by C-5 hydroxyl oxidation and sequential removal of protecting groups in aqueous acid, yielded D-lyxo-hexos-5-ulose (5-keto-mannose, 5) as a mixture of isomeric forms. The isomeric mixture of 5 in D2O solution was carefully examined using 1H and 13C NMR techniques and structural assignments were made for seven isomers. The most prevalent form of 5 observed was the ketofuranose isomer 2S, 5R-D-lyxo-hexo-5,2-furanos-5-ulose 1-hydrate (5a, 52%), with its 2S, 5S-ketofuranose anomer (5b) being the next most abundant (14%). Also identified in the mixture were the α and β-hexofuranos-5-uloses 5c (6%) and 5d (< 2%), the pyranose structure 1R,5R-lyxo-hexopyranos-5-ulose 5e (10%), and the anhydro isomer 1R,5R-1,6-anhydro-D-lyxo-hexopyranos-5-ulose (5f, 5%), present in 1C4 conformation. Limited spectral information suggests that the remaining isomer 5g (8%) is a hydrated acyclic aldehyde form of 5. 相似文献
Summary. The reaction of RuTp(COD)Cl (1) with PPh2Pri and terminal alkynes HCCR (R=C6H5, C4H3S, C6H4OMe, Fc, C6H4–Fc, C6H9) affords the neutral vinylidene complexes RuTp(PPh2Pri) (Cl)(=C=CHR) (2a–2f) in high yields. These complexes do not react with MeOH to give methoxy carbene complexes of the type RuTp(PPh2Pri)(Cl)(=C(OMe)CH2R), but react with oxygen to yield the CO complex RuTp(PPh2R)(Cl)(CO) (3). The structures of 2b, 2f, and 3 have been determined by X-ray crystallography. 相似文献