Aquation of K2 TcBr6 in dilute acid solutions

The photochemical aquation of K₂ TcBr₆ in 2M HRr, 1M HClO₄ and 1M H₂SO₄ has been studied. The absorption spectra of the various Tc(IV) species were measured after the electrophoretic separation. The spectrophotometric changes and the yield of each species as a function of the UV irradiation time were determined. After 25 hours of irradiation of HBr and HClO₄ solutions the main species were the cationic ones (80%) but in H₂SO₄ solution the neutral species reached a yield of 90%. The oxidation of Tc(IV) species to TcO ₄ ^– proceeded more rapidly and extensively in HClO₄ than in HBr and H₂SO₄.     

On Deciding between Space Groups Pnam and Pna21 for the Crystal Structure of Zr3N4

The crystal structure of Zr₃N₄ is shown to crystallize in the centrosymmetric space group Pnam rather than in the noncentrosymmetric space group Pna2₁.     

Contributions on the Properties of Titanates with Ilmenite Structure. IV. The effect of an order-disorder transition on the high temperature electrical conductivity of NiTiO3

NiTiO₃ shows an order-disorder transition from an ordered ilmenite structure to a corundum structure at high temperatures. The transition is followed by a strong increase of the specific electrical conductivity. The conductivity was investigated as a function of temperature and oxygen activity. An order parameter according to common phase transition theories can be used to describe the behaviour of the conductivity in the transition region and vice versa. A model for the defect structure of NiTiO₃ is presented.     

The aquation of hexachlorotechnetate(IV)

The photochemical decomposition of (NH₄)₂TcCl₆ in dilute HCl, HClO₄ and H₂SO₄ solutions has been studied. Electrophoresis and spectrophotometry were used to identify TcCl ₆ ^2? , TcCl₅ (H₂O)^?, cationic and uncharged species and TcO ₄ ^? . The yield of each species as a function of the time of uv irradiation was determined. The TcCl ₆ ^2? , yield decreases to zero after 50 h of irradiation. The TcCl₅(H₂O)^?, cationic and uncharged species and TcO ₄ ^? are formed in different proportions in the three acids. After 120 h of irradiation of the HCl solution the principal Tc species was the cationic one (≈70%) followed by the uncharged species (≈24%). In HClO₄ solution the cationic species (≈70%) was followed by TcO ₄ ^? , but in H₂SO₄ solution the uncharged species amounts to ≈90%.     

Refinement of the crystal structure of (RS)-carnitine hydrochloride

A single crystal of (RS)-carnitine hydrochloride has been obtained, and its crystal structure has been refined by an x-ray structural experiment.Tashkent Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 842–844, November–December, 1991.     

Comprehensive automation of the solid phase extraction gas chromatographic mass spectrometric analysis (SPE-GC/MS) of opioids,cocaine, and metabolites from serum and other matrices

The analysis of opioids, cocaine, and metabolites from blood serum is a routine task in forensic laboratories. Commonly, the employed methods include many manual or partly automated steps like protein precipitation, dilution, solid phase extraction, evaporation, and derivatization preceding a gas chromatography (GC)/mass spectrometry (MS) or liquid chromatography (LC)/MS analysis. In this study, a comprehensively automated method was developed from a validated, partly automated routine method. This was possible by replicating method parameters on the automated system. Only marginal optimization of parameters was necessary. The automation relying on an x-y-z robot after manual protein precipitation includes the solid phase extraction, evaporation of the eluate, derivatization (silylation with N-methyl-N-trimethylsilyltrifluoroacetamide, MSTFA), and injection into a GC/MS. A quantitative analysis of almost 170 authentic serum samples and more than 50 authentic samples of other matrices like urine, different tissues, and heart blood on cocaine, benzoylecgonine, methadone, morphine, codeine, 6-monoacetylmorphine, dihydrocodeine, and 7-aminoflunitrazepam was conducted with both methods proving that the analytical results are equivalent even near the limits of quantification (low ng/ml range). To our best knowledge, this application is the first one reported in the literature employing this sample preparation system.     

Tetrakis(pentafluoroethyl)gallate, [Ga(C2F5)4]−, Ionic Liquids

We synthesized new imidazolium-based tunable aryl alkyl ionic liquids (TAAILs) with the weakly coordinating tetrakis(pentafluoroethyl)gallate anion, [Ga(C₂F₅)₄]⁻. Phenyl and phenyl derivatives (2-Me, 4-OMe, 2,4-F) were combined with varying alkyl chain lengths at the imidazolium core leading to TAAILs, which were investigated with regard to their viscosity, conductivity, and electrochemical window and compared to EMIM and BMIM standard cations. Remarkable low viscosities of 29 cP at 25 °C for [BMIM][Ga(C₂F₅)₄] were achieved. However, the EMIM and BMIM gallates show electrochemical instability, releasing pentafluoroethane at a voltage of 1.5 V. The 2-Me-substituted gallate-TAAILs slowly decompose over several weeks, whereas all other gallate-TAAILs showed no decomposition at all. With electrochemical windows of up to 5.15 V and low viscosities in a range of 66–162 cP, the gallate-TAAILs are promising candidates as electrolytes in electrochemical applications.     

Various carbon dust particles

Nano-sized carbon dusts are suspected of having negative effects on human health. An exact characterization of such particles is necessary to understand possible toxic effects, i.e. in the lung. Observed by transmission electron microscopy (TEM), the carbon dusts are a composite of very small primary particles and larger agglomerates of these. A differentiation of the primary particles and agglomerates according to source is not possible by TEM, however, thermogravimetry investigations in synthetic air atmosphere are helpful. Standardized carbon black and graphite show a single-step oxidation behaviour, whereas ethene soot and diesel soot, for example, show more complex-reaction mechanisms. The results of ethene soot exemplarily demonstrate the oxidation mechanism. In addition to the oxidation reaction to carbon dioxide, a sintering process takes place. To confirm the oxidation mechanism, thermal behaviour of ethene soot has been simulated by kinetic modulation using a three-step reaction mechanism of n-th order. The reaction order indicates a complex mechanism for the first-reaction step. For the second and third-reaction step, a phase boundary mechanism could be suggested.