The solubility of alkali-metal fluorides in non-aqueous solvents with and without crown ethers, as determined by flame emission spectrometry

The solubilities of LiF, NaF, KF, RbF and CsF in acetonitrile, acetone, tetrahydrofuran, dimethylformamide, benzene and cyclohexane have been determined with and without a crown ether (usually 0.1 M 18-crown-6) present. Flame emission spectrometry was the determination method. Three procedures, selected according to the miscibility of the solvent with water, and the solubility of the fluoride, are described. Samples, standards and blanks were matrix-matched. The precision varied between 1 and 10% RSD. Although extensive drying procedures were applied, moisture present in the solvents and salts had some effect on the results.     

Peaceful pyrolysis-a novel method for the decomposition of metal-perchlorate complexes of organic ligands

Perchlorate complexes of vanadium(IV), iron(III), dysprosium, yttrium, copper(II) and nickel with the organic ligands dimethyl sulphoxide, antipyrine, 4-aminoantipyrine, 4-(2-hydroxynaphthyl)-azoantipyrine, and 4-(2,4-dihydroxyphenyl)azoantipyrine have been prepared and analysed for their metal content after decomposition by a non-explosive pyrolytic technique, viz. heating with ammonium chloride. The results obtained agree with those obtained by the standard methods. This pyrolytic technique is found to be very convenient, rapid and accurate.     

Kinetic studies of solvent extraction of metal complexes—IX. Rate of complex formation of chromium(III) with acetylacetone in aqueous perchlorate solutions and in two polar organic solvents

The rate of complex formation of chromium(III) with acetylacetone in aqueous perchlorate solutions was determined by a solvent extraction method in 4-methyl-2-pentanone and 4-methyl-2-pentanol. The rate of complex formation in the organic solvents was also studied by a spectrophotometric method. On the basis of the results that the rate of complex formation was nearly the same in these three media, a mechanism for the extraction of the metal ions in aqueous perchlorate solutions with acetylacetone into these polar organic solvents was proposed.     

Dimerization of copper(II) decanoate in 1,4-dioxane-water mixed solvents

Complex formation of copper(II) with decanoic acid (HA) has been studied by potentiometric measurement in 1,4-dioxane-water mixtures at a constant ionic concentration of 0.1 mol dm^?3 (Na, H)ClO₄ and at 25°C. The experimental data can be interpreted with the formation of CuA⁺, CuA₂ and Cu₂A₄. The dimerization constant formulated as:

was found to be log K_dim = 3.75, 4.02 and 4.26 for 0.3, 0.4 and 0.5 mole fractions of dioxane, respectively. Absorbances at 373 and 670 nm are interpreted with the aid of the formation constants determined by potentiometry. Solvent effect on the dimerization of the monomeric copper(II) decanoate is discussed on the basis of selective solvation of CuA₂ and Cu₂A₄ with water molecules.     

Formation equilibria of copper(II) complexes with some pyridinols in various solvents

Complexation of copper(II) with two different pyridinols in three solvents has been studied by visible spectrophotometry and flow-microcalorimetry. The influence of the solvent on tautomeric equilibrium of the ligand, on distribution, on stability and on formation enthalpies of the main complex species is discussed.     

The solubility of uranium(IV) hydrous oxide in sodium hydroxide solutions under reducing conditions

The solubility of hydrous UO₂ in sodium hydroxide solutions containing sodium dithionite and/or Zn metal powder as reductants has been measured. The results provide no firm evidence for any amphoteric behavior of U(IV) but do set an upper limit of K ≤ 2 x 10^?23 for the hypothetical reaction:

The results provide no evidence for such a reaction.     

Thallium-205 NMR study of ti(I) macrocyclic complexes in nonaqueous solvents

Thallium-205 and carbon-13 NMR measurements were used to determine, in nonaqueous solvents, the stabilities of thallium(I) complexes with macrocyclic ligands of different structures but very nearly the same cavity sizes. In a given solvent the complexing abilities of the ligand vary in the order DA18C6 > 18C6 > DC18C6 > DB18C6 > DT18C6. In all cases the stabilities of the complexes varied inversely with the Gutmann donicities of the solvents.     

Spectrophotometric determination of saccharin in different materials by a solvent extraction method using Nile Blue as reagent

In a slightly acidic medium (sodium acetate-acetic acid buffer, pH 4) saccharin and Nile Blue form an ion-association compound which is extractable into methyl isobutyl ketone and allows the spectrophotometric determination of saccharin. At 630 nm Beer's law is obeyed over the saccharin concentration range 0.1-3.5 microg/ml in the aqueous phase and the apparent molar absorptivity is 5.8 x 10(4) l.mole(-1).cm(-1). The method shows good selectivity and can be applied to the determination of saccharin in artificial sweeteners, soft drinks and toothpastes.     

Electrochemical reduction of dialkylamide and bis-trimethylsilylamido complexes of chromium(III) and ytterbium in non-aqueous solvents

The electrochemical reductions of (a) Cr[N(SiMe₃)₂]₃, Cr(NPrⁱ₂)₃, Cr(NO)[N(SiMe₃)₂]₃, Cr(NO)(NPrⁱ₂)₃ and Cr(NO)(OBu^t)₂(NPrⁱ₂) in acetonitrile, and (b) Yb[N(siMe₃)₂]₃ in dimethylsulphoxide, have been studied using cyclic voltammetry (platinum bead electrode) and controlled potential coulometry (mercury pool electrode). The results are interpreted in terms of quasi-reversible or irreversible one-electron reduction and possible side-reactions. A number of similar complexes of titanium, vanadium, manganese, iron and cobalt were investigated but electrochemical studies were precluded due to reactions with solvent and/or supporting electrolyte.     

A new method for the trifluoromethylation of aromatics

A new method is discribed for introducing a CF₃-group, by a single-step synthesis, into aromatic compounds. This trifluoromethylation is done by means of a mixture consisting of HF/CCL₄ and the aromatic compound. The reaction is thought to be of a Friedel-Crafts type and limited to aromatics which are not substituted by electron withdrawing groups.     

Phase equilibria for the separation of aromatic and nonaromatic compounds using mixed solvents. Part I. The system n-heptane—toluene—N-methylpyrrolidone/monoethyleneglycol

The solvent combination of N-methylpyrrolidone (NMP) and monoethyleneglycol (MEG) is used in industry for the separation of aromatics and nonaromatics (Arosolvan process).In this paper experimental results obtained for the system n-heptane—toluene—N-methylpyrrolidone/monoethyleneglycol are presented. Liquid—liquid equilibrium compositions were obtained at three different temperatures (50°C, 60°C, 70°C). For each temperature, three different solvent compositions corresponding to weight ratios of NMP/MEG equal to $\text{50}\text{50}$, $\text{62}\text{38}$ and $\text{70}\text{30}$ were considered. The different sets of experimental results obtained are correlated using the NRTL equations.Equilibrium compositions obtained using an industrial solvent mixture (NMP/MEG-$\text{58}\text{42}$) are compared with data based on the use of purified solvents.     

Specific effects of simple organic sulphonate anions on the mercury ion-assisted aquation of chlorocobalt(III) complexes: Deviations from the primary s

Kinetic effects of various 1-1 electrolytes on the CoClL_n² + Hg² reaction (L_n: neutral ligands) were studied with varying concentra     

Study of the complexes of Np(V) with organic ligands by solvent extraction with TTA and 1, 10-phenanthroline

Complex formation constants of Np(V) with 22 organic ligands, 7 hydroxycarboxylic acids, 4 dicarboxylic acids, 4 aminocarboxylic acids, 3 pyridinecarboxylic acids, 8-hydroxyquinoline-5-sulfonic acid, IDA, NTA and EDTA, have been determined in 1M NaClO₄ at 25°C by using the solvent extraction method with TTA and 1, 10-phenanthroline. The factors influencing the stabilities of Np(V) complexes are discussed in connection with the linear structure of NpO₂⁺.     

Electrochemical typing of blood using affinity membranes

Human blood group substance of the ABO system was immobilized in a mebrane matrix. The membrane-bound blood group substance retained its binding ability against the corresponding antibody (agglutinin) in serum. The transmembrane potential changed drastically with the agglutination of the membrane-bound blood group substance. Electrochemical typing of blood was performed with sera, using a pair of membranes with immobilized A- and B-type blood group substances. The blood type was determined by measuring the transmembrane potential across these membranes before and after the agglutination reaction. A possible re-use of the membrane-bound blood group substance by treatment with galactose is discussed.     

Cyanato-copper(II) complexes with organic ligands—XXIV. Diisocyanato-bis(3,5-dimethylpyrazole)copper(II)—the cyanate member of the coligand isomer

The title compound was prepared, and found to be isomeric with the known bis(1-carbamoyl-3,5-dimethylpyrazolato)copper(II). Its IR, far-IR, electronic     

Synthesis and spectral studies on platinum complexes with mono- and bidentate N-donor organic ligands

Platinum(II) complexes of types PtLX₂, PtL₂X₂, PtLX″ and the Pt(IV) complexes PtLXY (where L = mono- or bidentate organic ligand containing nitrogen donor atoms; X = Cl or Br; X′ = oxalate or malonate and Y = Br) have been synthesized and characterized from their elemental analysis, IR and X-ray photoelectron spectral data. The Pt 4f_7/2 binding energies indicate that 1,8-naphthalene-diamine ligand is a better donor of electron density to the metal than other ligands studied here. The Cl 2p_3/2 binding energies in the square planar Pt(II) complexes are observed in the range 198.8 ± 0.8 eV. The ν (PtCl) vibrations (ca 335 and 320 cm^?1) corresponding to two cis-Cl ligands were observed in the IR spectra.The extent of the interaction between cis-dichloro-bis-(theophylline)platinum(II) with calf thymus DNA has beenstudied. The UV difference spectra resulting from aquated Pt^II(theoph)₂-DNA interaction exhibit bands at 282 and 292 nm attributable to the change in the electron distribution of the base moieties induced by binding with platinum and due to the loss of base stacking. Melting profiles for the DNA samples treated with Pt-complex showed decrease in the melting temperature. Binding of the guanine residues of the DNA, involving probably (N7)-0(6) positions to the metal is implied.     

A reaction-rate method for the determination of thiocyanate,based on its inhibitory effect on the iodate-hypophosphite reaction

An automatic spectrophotometric reaction-rate method is described for the determination of thiocyanate in aqueous solutions, based on its inhibitory effect on the iodate-hypophosphite reaction. The time required for the reaction to proceed between two pre-determined levels is measured automatically and related directly to the thiocyanate concentration. The recommended reaction-rate method is fast, simple, sensitive, accurate (to 2%) and precise (1.7%, relative standard deviation). The useful analytical range of concentrations of thiocyanate is 4 × 10^?5 to 5 × 10^?4M. Maximum tolerable amounts of interfering ions are also presented.     

Improvement of the variable volume cell method of simultaneous determination of saturation pressure and liquid molar volume

Rousseaux, P. And Richon, D., 1985. Improvement of the variable volume cell method of simultaneous determination of saturation pressure and liquid molar volume. Fluid Phase Equilibria, 19: 295-301.The optimization study performed for the variable volume cell technique using a piston or a bellows consisted of the following two stages : first, a study of the method used in treating the pressure-volume data to obtain the researched magnitudes values, bubble pressure and saturated liquid phase density, was performed ; secondly, the individual components of the measuring instrument were examined to determine their degree of influence on the final precision of the results.     

Potentiometric investigation of sparingly soluble metal-ligand systems using metal-ion buffers

A novel approach based on metal-ion buffers has been used to determine metal-ligand formation constants for a variety of sparingly soluble systems. It is suggested that the approach will be particularly useful in the study of metal binding by pharmaceuticals.     

A new graphical method based on stoichiometric dilution for the classification of binary complexes with mole ratio 1:1

A simple approach to the treatment of spectrophotometric data obtained by stoichiometric dilution is presented for complexes of the type M(m)B(n) and m/n = 1. The values of m and n are obtained by matching the slope of a straight line with a mathematically predicted value. The method can be applied to moderately strong complexes, the concentration of which can be determined by absorbance measurements, and allows calculation of the formation constant as well.