Solvent extraction for cleaning phosphoric acid in fertilizer production

Phosphorites of sedimentary origin utilized in manufacturing of fertilizer contain uranium, thorium and products of their radioactive decay, as well as health-endangering compounds of cadmium, arsenic and fluorides. Some of them may transit into the phosphoric acid, when breaking down the phosphorites with sulphuric, acid, and then into the fertilizer. The purpose of the phosphoric acid cleaning is its decontamination from uranium and thorium as well as the removal of toxic cadmium. The above task can be achieved by solvent extraction. The paper presents the results of the extraction of uranium and cadmium from phosphoric acid using polyalkyl phosphasene and trioctyl amine, respectively. The extraction kinetics, equilibrium distribution of uranium and cadmium within the phases, the effect of extractant concentrations and temperature of the process is also discussed. The technological schemes for cleaning phosphoric acid from uranium and cadmium are given.     

Synthesis of N-benzyloxycarbonyl-N-methylaminoacids from oxazolidine-5-one derivatives

Hydrogenolysis of 3-benzyloxycarbonyloxazolidine-5-one and 3-benzyloxycarbonyl-4-benzyloxazolidine-5-one by Et₃SiH in the presence of F₃.CCO₂H is demonstrated to be a convenient method for preparing substituted N-methylaminoacids. In contrast with catalytic hydrogenation on Pd/C catalyst, the benzyloxycarbonyl is not removed and the methyl is not lost using this method.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 681–683, May, 1992.     

Isotope gas analysis of tritium-labelled organic compounds based on pyrolytical decomposition

Summary A procedure has been developed for the activity measurement of tritium-labelled organic compounds in the gas phase. The organic compounds are pyrolysed in hydrogen carrier gas at 1150° and the decomposition products are swept through a carbon packing in accordance with the principle of the oxygen determination developed byUnterzaucher andBürger. The radioactive gas mixture obtained from the sample is swept by the hydrogen carrier gas flowing continuously through the reactor into a proportional counter tube, after the addition of propanebutane counter gas. By closure of the counter tube at a suitable moment, the radioactive gas is quantitatively trapped in the counter tube. The activity is measured in the limited proportional region. No memory effect occurs. The preparation of the sample requires 12 minutes; the relative standard deviation of analysis is <0.5%.

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Zusammenfassung Ein Verfahren zur Aktivitätsbestimmung bei tritium-markierten organischen Verbindungen in der Gasphase wurde ausgearbeitet. Die organischen Substanzen werden in Wasserstoff als Trägergas bei 1150° pyrolysiert. Die Zersetzungsprodukte werden wie bei der Sauerstoffbestimmung nachUnterzaucher bzw.Bürger über eine Kohleschicht geleitet. Das radioaktive Gas-gemisch aus der Probe gelangt mit dem kontinuierlich strömenden Trägergas in ein Proportionalzählrohr, nachdem Propan-Butan-Zählgas zugesetzt wurde. Man schließt das Zählrohr im richtigen Augenblick, um das radioaktive Gas quantitativ zu erfassen. Die Aktivität wird im Proportionalbereich gemessen. Ein Memory-Effekt tritt nicht auf. Die Vorbereitung der Probe beansprucht 12 Minuten. Die relative Standardabweichung ist kleiner als 0,5%.

     

Synthesis of 3-imino and 3-ylideno derivatives of 4-fluoro-5-polyfluoroalkyl-1,2-dithiolenes

Reactions of 4-fluoro-5-polyfluoroalkyl-1,2-dithiol-3-thiones with hydroxylamine and hydrazines occur with replacement of the thiocarbonyl by imino group affording oximes and hydrazones respectively. N-Alkyl-and N-aryl-3-imino-1,2-dithiolenes formed in reactions of 3-chlorothio-1,2-dithiolium salts with primary alkyl-or arylamines. 3-Chlorothio-1,2-dithiolium salts react with compounds possessing an active methylene group yielding 3-ylideno derivatives of 1,2-dithiolenes.     

Phosphorus-containing Small Rings: X. Phosphorylation of Derivatives of 1-Methyl-2,2-dichlorocyclopropanecarboxylic Acid

Reaction of derivatives of 1-methyl-2,2-dichlorocyclopropanecarboxylic acid with three- and four-coordinate phosphorus acids was studied. It was established that the nucleophilic substitution on the carbonyl carbon atom proceeds without cleavage of the three-membered ring and leads to new types of phosphorus-containing cyclopropanes. The products were found to enhance the germination energy and laboratory germination of cereal, legume, and vegetable seeds.     

Effect of Pyrophosphate Ions on the Mechanism of Discharge–Ionization of Copper in Acid Sulfate Solutions

The acceleration of the electrodeposition and anodic dissolution of copper in acid sulfate solutions, caused by sodium pyrophosphate, is found to be due to a chemical heterogeneous stage, which involves an adsorbed pyrophosphate ion (probably, H₂P₂O₇ ^2–). The assumption about the presence of a surface complex on the surface of copper is substantiated. As follows from adsorption isotherms, obtained for strongly acid (to 2 M H₂SO₄) solutions from anodic Tafel plots, the effect of the acid concentration on the rate of the discharge–ionization of copper is caused by its effect on the surface coverage by the adsorbate. Measurements of the quasi-equilibrium potential of the freshly renewed surface of copper confirm the assumption about the inhibiting of the surface diffusion of adsorbed atoms by adsorbed pyrophosphate.     

EPR spectroscopy and polarography of nitroazoles. 3. Nitropyrazoles

The results of an EPR investigation are presented with polarographs of electrochemical excitation of nitropyrazoles in acetonitrile. It is shown that 3- and 4-nitropyrazoles are excited in two single-electron stages with formation of dianion radicals. Upon excitation, N-alkylnitropyrazoles form stable anion radicals. 1-Nitro- and 1,4-dinitropyrazoles are excited upon splitting off of the NO₂ anion. Excitation potentials of the nitropyrazoles and hyperfine interaction constants for the corresponding ion radicals are given.See [1] for Communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 523–527, April, 1982.     

Plasma-Enhanced Chemical Vapor Deposition of Silicon Carbonitride Films from Volatile Silyl Derivatives of 1,1-Dimethylhydrazine

Silicon carbonitride films were synthesized from new volatile precursors by plasma-enhanced chemical vapor deposition. Based on a detailed study of the morphology of film surfaces, it was found that the layer material was an amorphous matrix with inclusions of nanosized crystals. Calculation of the structure of the crystalline phase from synchrotron X-ray diffraction patterns demonstrated that the entire set of the diffraction peaks detected is indexed by a tetragonal structure with the lattice parameters a = 9.6 Å and c = 6.4 Å. This is consistent with the fact that the carbon 1s and nitrogen 1s core level X-ray photoelectron spectra exhibited only sp ³ bonding, which was expected for superhard carbon nitride phases.     

Tetraphenylbismuth 2,4-Dimethylbenzenesulfonate: Synthesis and Structure

Tetraphenylbismuth 2,4-dimethylbenzenesulfonate was synthesized by reacting pentaphenylbismuth or bromine with diphenylbismuth 2,4-dimethylbenzenesulfonate and its structure was established using X-ray diffraction analysis. The Bi atom has a distorted trigonal bipyramidal coordination. The Bi–C bond lengths are equal to 2.199(4)–2.227(4) Å the Bi–O distance and axial CBiO angle are equal to 2.665(3) Å and 174.2(1)°, respectively.     

Kinetics of Gold Electrodeposition from Cyanide Electrolytes at a Monitored Surface Coverage by Thallium Atoms

A procedure for measuring kinetic parameters of gold electrodeposition in the presence of catalytically active thallium(I) ions while monitoring the coverage of the gold surface by thallium adatoms, , is described. The procedure accounts for the duration of contact between a freshly renewed surface of gold and a thallium-containing solution and assumes that the incorporation rate of thallium adatoms is proportional to and the current density of gold electrodeposition. At = const, kinetic dependences correspond to the Tafel equation. Values of and i ₀ increase with . At = 0.3, 0.6 and i ₀ 3 × 10^–4 A cm^–2, which conforms to values calculated from anodic curves obtained in similar conditions.