Chromatographic study of anionic complexes

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 R_f 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 R_f values decrease with the addition of tartrate in the beginning. Then the value increases and finally becomes constant. In case of Cd²⁺ the R_f value decreases by the addition of tartrate. In 60% ethanol the R_f value does not change by small additions of tartrate but decreases with higher concentration of the complexing agent. In case of Cd²⁺ the R_f value becomes zero by increasing the concentration of tartrate.Part I: See Z. analyt. Chem. 159, 332 (1957/58).     

Chromatographic study of metal ammines

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 R_f values. In the case of Cu^II and Ni^II the R_f value decreases, while in the case of Ag^I, Cd^II and Co^II it increases with increasing concentrations of NH₄OH added. With progressive increase in the concentration of NH₄OH the R_f values finally tend to become constant.     

Thin Layer Chromatographic of Metal Ions in Oxalic Acid-Oxalate Systems

Abstract

The adsorption behaviour of 48 metal ions has been studied in Oxalic acid - Oxalate systems using silica gel - G layers. The effect of p_H on R_f values was also investigated. A plot of -log Ksp Vs. R_M and R_f 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.     

Prediction of KSP from Rf Values: Thin Layer Chromatography of 47 Metal Ions on Stannic Arsenate in Aqueous Hydrochloric Acid Systems

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 R_f alongwith the complexation effect of HCl has been investigated. On the basis of R_f values the K_SP 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⁺.     

Chromatographic behaviour of metal ions on tin(IV) and titanium(IV) antimonate papers

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⁺=R_M + 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 R_f, R_i, log R_f and R_M values of metal ions has also been examined in aqueous systems.     

Simultaneous determination of levofloxacin hemihydrate and ambroxol hydrochloride in tablets by thin-layer chromatography combined with densitometry

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 F ₂₅₄ 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 (R _f value of 0.4) and AMB (R _f value of 0.7). The calibration curves for LEV and AMB was found to be linear between 9960–16600 ng/spot (r ² = 0.999) and 600–1000 ng/spot (r ² = 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.     

Chelation Ion Chromatography on DMSO Impregnated Silica Gel-G Layers: Specific Separation of Cd2+, W6+, and Zr4+ from Transitional Metal Ions

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 R_f 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.     

Normalized potential sweep voltammetry: Part III. Elimination of the effect of uncompensated Resistance and the application to heterogeneous kinetics of rapid charge-transfer processes

Uncompensated resistance (R_u) has a distoring effect on normalized potential sweep voltammetry (NPSV) slopes. This provides a simple and effective method to determine R_f^o, 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 I_N of 0.20–0.50 and 0.50–0.80 respectively, the slopes m₁ and m₂ differ significantly when R_f differs form R_f^o. The difference, m₁-m₂, is negative for R_f<R_f^o and positive for R_f>R_f^o. Fine tuning of the potentiostat R_f 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 m_T, 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.     

Action des perfluoroalkylcuivre(I) sur les perfluoroalkylethylenes

A series of new polyfluorinated dienes 3, containing the novel -CFCHCHCF-, pattern has been synthesized (50–70% yields) by reacting perfluoroalkyl iodides with perfluoroalkyl-ethylenes in the presence of copper. The monoalkenes R_fCFCHCH₂CF₂R′_f and the saturated compounds R_fCF₂CH₂CH₂CF₂R′_f were obtained by varying the experimental conditions. The ¹H and ¹⁹F NMR spectra are analysed and the reaction mechanism is discussed.     

Medium effects upon the kinetics of formation of nickel(II) and cobalt(II) pyridine 2-azo-p-dimethylaniline

Summary The kinetics of formation of the Ni^II and Co^II 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 K_f of Ni(PADA)²⁺ to about 50% of the value in water. A concentration of 2.0 mol dm^–3 NaCl doubles k_f 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.     

Chromatographische Enantiomerentrennung,chiroptische Eigenschaften und absolute Chiralität von Pentacyclo [7.4.1.12,7 .01,9 .02,7]pentadeca-3,5,10,12-tetraen-8-on,einem pentacyclischen Cyclopentanonderivat mitC 2-Symmetrie

The title compound1 was resolved into enantiomers by medium-pressure liquid chromatography on microcrystalline triacetylcellulose in ethanol. After four cycles pure enantiomers were obtained ([] _D ²⁰ + 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.

     

UV-Aufschlu? organischer Wasserinhaltsstoffe bei spurenanalytischen Multielement-Anreicherungen, speziell an Chelat-Ionenaustauschern

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     

Calculations of Monomer Conversion and Radical Concentration in Reversible Addition‐Fragmentation Chain Transfer Radical Polymerization

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, k_f, is higher than 10 s⁻¹ or when the cross‐termination rate constant, k_ct, 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.     

Grafting Vinyl Monomers onto Poly(ethylene Terephthalate) (PET). IV. Graft Copolymerization of Methyl Methacrylate onto PET Fibers Using Acetyl Acetonate Complexes of Mn(III), Co(III), and Fe(III)

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, R_p, 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.     

Novel ammonium hexafluoroarsenate salts from reaction of (CF3)2NH,CF3N(OCF3)H,CF3N[OCF(CF3)2]H,CF3NHF and SF5NHF with the strong acid HF/ASF5.

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 R_f¹R_f²NH₂⁺AsF₆^? and R_fNFH₂⁺ AsF₆^? in high yield. [R_f¹=CF₃, R_f²=CF₃, CF₃O, (CF₃)₂CFO; R_f=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 (R_fNFH₂⁺ AsF₆^?) to ～50 torr [CF₃N(OCF₃)H₂⁺AsF₆^?]. ¹⁹F NMR and Raman spectroscopy were used to identify the compounds.     

Solvation numbers and hydration constant for thorium(IV) in ethanol-water medium

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) ₃ ⁴⁺ Formation of thorium monochelate with lawsone (2-hydroxy-1,4-naphthoquinone) eliminates bonding with alcohol molecules. The dissociation constant of the chelating agent_sK_a and the formation contant of the monochelated metal ion_sK _f ^* 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,_sK _f ^* 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 vpK_a is the dissociation constant of the chelating agent LH in the solvent system of ν volume fraction of water and_sK_h is the solution-independent hydration constant of thorium (IV) in the solvent system. Log-values for the constants_sK_h,_sK _f ^* and_sK _a ^* are found to be 7.8±0.02, 11.38±0.04 and ?0.753, respectively.     

Fluorination of perfluoroalkylsulfenyl chlorides,perfluorodialkyl disulfides and perfluorodialkyl sulfides with chlorine monofluoride

In reactions with perfluoroalkylsulfenyl chlorides (R_fSCl; R_f = F₃, C₂F₅, n-C₃F₇, n-C₄F₉) and perfluoroalkyl disulfides (R_fSSR_f′; R_f = R_f′ = CF₃, R_f = CF₃, R_f′ = C₂F₅) at 25°, chlorine monofluoride acts primarily as a chlorinating and fluorinating reagent to give the corresponding perfluoroalkylsulfur chloride tetrafluorides, R_fSF₄Cl, in good yields. However, small amounts of perfluoroalkylsulfur pentafluorides, R_fSF₅, 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.     

Identification of Some Closely Related N-Carbamoyl-3,5-Dimethyl-4-Arylazopyrazoles by TLC

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 R_f value with Hammett substituent constant (σ) is also interpreted.     

5-Keto-Mannose (D-Lyxo-Hexos-5-Ulose) in Aqueous Solution-Isomeric Composition Dominated by α/β D-Fructofuranose Related Structures

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 ¹ C ₄ conformation. Limited spectral information suggests that the remaining isomer 5g (8%) is a hydrated acyclic aldehyde form of 5.     

Ruthenium Tris(pyrazolyl)borate Complexes. Part 20 [1]. Synthesis,Characterization, and Reactivity of Neutral Trispyrazolylborate Ruthenium Vinylidene Complexes

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.