Separation and determination of zirconium and hafnium in uranium matrix

Hafnium and zirconium are separated from uranium using an anion exchange resin column. The two elements are then separated from each other using extraction chromatography and determined separately by precipitation as tetramandelate. The determination method was verfied by isotopic cilution technique. The method proved to be selective, quantitative (>99%) and gives an error of <±2%.     

Applications involving oxidation with KBrO3: I. Rapid potentiometric method for manganese alone or in steel and some ores

A rapid and reliable method is developed for the determination of manganese based on oxidation of the divalent cation with a known excess of KBrO₃ to the tetravalent state. The unreacted oxidant as well as Mn(IV) are then reduced with H₂SO₃ to Br^? and Mn(II). The resulting Br^? is titrated with Ag₂SO₄ using silver metal as the indicator electrode. K₂SO₄ is added to increase sensitivity and establish equilibrium in the vicinity of the end point. Fe(III) when present is also reduced with SO₂ to the divalent state, which can be reoxidized with Br₂. The equivalent amount of bromide is again titrated with Ag₂SO₄. The method provides for the simultaneous determination of Mn and Fe and finds application to some ores and steels.     

The use of iodate and periodate with iodide in the potentiometric titration of arsenite,sulfide, and sulfite with mercury (II)

A new potentiometric method is adopted for the accurate microdetermination of arsenite, sulfide and sulfite. The reductant is added to a known excess of standard iodate or periodate properly acidified with sulfuric acid. To the brown solution containing iodine equivalent to the reductant, an excess of standard iodide solution is added followed by titrating unreacted iodide with mercury (II) potentiometrically using the silver amalgam as indicator electrode. The potential breaks which averaged 350 mV per 0.1 ml of 0.05 M titrant were sharp enough for the precise determination of end points, and hence the high accuracy of the present method. In addition, besides simplicity and rapidity the stoichiometry of the reaction between iodate or periodate with the above reductants is still maintained even with the very low concentration.     

Ion-pair extraction of Co(II) by crown ethers from perchlorate medium

The extraction of cobalt(II) by chloroform solutions of the crown ethers (CE) 12C4, I5C5, 18C6, Dbl8C6, Dchl8C6 or Dch24C8 from aqueous perchlorate medium was investigated. Slope analysis of the experimental data suggested that the extraction of Co(II) by these CEs takes place through ion-pair formation, and that the chemical formula of the main extracted species is Co(OH)(+)ClO(-)(4).CE. The magnitudes of the extraction constants are in the sequence 18C6 > Dch18C6 > Dch24C8 > Db18C6 > 15C5 > 12C4, which is discussed in terms of the correspondence between the CE cavity size and the ionic radius of cobalt(II).     

Reactions with heterocyclic amidines,VII: Synthesis of some new pyrazolo[1,5-c]-1,2,4-triazines,pyrazolo[1,5-a]-1,3,5-triazines and pyrazolo[1,5-a]pyrimidines

Diazotised 5-amino-3-methyl-4-phenyloyrazole (1) reacted with active methylene reagents and with -naphthol to yield the pyrazolo[1,5-c)-1,2,4-triazine derivatives2a-e and5. Compound1 reacted with benzoyl isothiocyanate and with phenyl isothiocyanate to yield the corresponding pyrazol-5-ylthiourea derivatives6a, b. 5a was converted into the thiourea derivative8 by the action of acids or alkalies. A synthesis of 2-methyl-3-phenyl-4,5,6,7-tetrahydropyrazolo[1,5-a]-pyrimidin-5-one from the reaction of -phenylacetoactonitrile (3-oxo-2-phenyl-butyric nitrile) and -cyanoethylhydrazine is reported.

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Reaktionen mit heterocyclischen Amidinen, VII: Synthese einiger neuer Pyrazolo[1,5-c]-1,2,4-triazine, Pyrazolo[1,5-a]-1,3,5-triazine und Pyrazolo[1,5-a]pyrimidine

Zusammenfassung Diazotiertes 5-Amino-3-methyl-4-phenylpyrazol (1) reagiert mit einer aktiven Methylenkomponente und -Naphthol zu den Pyrazolo[1,5-c]-1,2,4-triazin-Derivaten2a-e und5. 1 ergibt mit Benzoylisothiocyanat und Phenylisothiocyanat die entsprechenden Pyrazol-5-yl-thioharnstoffe6a, b. 5a wurde mittels Säure oder Base in das Thioharnstoffderivat8 umgewandelt. Es wird über eine Synthese von 2-Methyl-3-phenyl-4,5,6,7-tetrahydropyrazolo[1,5-a]-pyrimidin-5-on aus -Phenylacetoacetonitril (3-Oxo-2-phenyl-butyronitril) und -Cyanoethylhydrazin berichtet.

     

Metal chelates of some transition and non-transition metal ions with Schiff base derived from isatin witho-phenylenediamine

Summary New Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) chelates of the Schiff base derived from isatin witho-phenylenediamine have been synthesized and characterized on the basis of elemental analyses, electronic, IR and¹H NMR spectra, and also by aid of molar conductivity and magnetic moment measurements. It has been found that the Schiff base behaves as ONNO tetradentate dibasic ligand forming chelates with 1:1 (metal:ligand) stoichiometry. Square planar environment is suggested for nickel(II) chelate. All the metal chelates show non-electrolytic behaviour.

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Metallchelate einiger Übergangs- und Nichtübergangsmetallionen mit Isatin-o-Phenylendiamin-Schiff-Basen

Zusammenfassung Es wurden neue Chelate von Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) und Pb(II) mit Schiff-Basen aus Isatin undo-Phenylendiamin hergestellt und mittels Elementaranalysen, Elektronen-, IR- und¹H-NMR-Spektroskopie, sowie durch Messung der molaren Leitfähigkeit und der magnetischen Momente charakterisiert. Es wurde festgestellt, daß sich die Schiff-Base als vierzähniger zweibasischer ONNO-Ligand verhält, wobei 1:1-stöchiometrische Metall:Ligand-Komplexe gebildet werden. Für das Nickel(II)-Chelat wird eine quadratisch-planare Geometrie vorgeschlagen. Alle untersuchten Metallchelate zeigen ein nicht-elektrolytisches Verhalten.

     

Applications involving oxidation with potassium bromate : II. Potentiometric titration of chromium alone or in mixtures

A rapid and reliable determination of chromium was developed based on bromate oxidation of chromium(III) to chromium(VI). The reaction is complete under weakly acidic conditions and with cobalt(II) present as a catalyst. Unreacted bromate and chromium(VI) are then reduced with sulfite to bromide and chromium(III). The bromide is titrated potentiometrically with mercury(I) using a silver amalgam indicator electrode. Iron(III) if present is reduced by sulfite to iron(II) and does not interfere. Some binary and ternary metal mixtures containing chromium can be resolved by the determination of chromium, alone or with another metal, by the above procedure coupled with procedures for further sample portions involving the potentiometric titration of unreacted CyDTA or iodide, or both, with mercury(II).     

Tryptophan analysis simultaneously with other amino acids in gas phase hydrochloric acid hydrolyzates using the Pico-TagTM Work Station

Summary Classical liquid phase hydrolysis of proteins with hydrochloric acid in the presence of tryptamine [3-(2-aminoethyl)indole] has shown that tryptophan can be protected from destruction. An exhaustive study has been made to establish the optimum conditions for protein hydrolysis, in the gas phase using the Pico-Tag^TM Work Station, as a function of time and temperature. The amino acid content, including tryptophan and cyst(e)ine, of standard proteins such as lysozyme, human albumin and -chymotrypsin were determined as phenylthiocarbamyl (PTC) derivatives. On 5 m Hypersil columns (15×4.6 mm) the quantitation of twenty PTC amino acids requires 22 minutes. The reproducibility of the measurements was 5.8% (relative standard deviation) or less.     

A collocation method with cubic B-splines for solving the MRLW equation

The modified regularized long wave (MRLW) equation is solved numerically by collocation method using cubic B-splines finite element. A linear stability analysis of the scheme is shown to be marginally stable. Three invariants of motion are evaluated to determine the conservation properties of the algorithm, also the numerical scheme leads to accurate and efficient results. Moreover, interaction of two and three solitary waves are studied through computer simulation and the development of the Maxwellian initial condition into solitary waves is also shown.     

Synthesis,Characterization, and Pharmacological Evaluation of Some New Pteridine‐Based Heterocycles as Antimicrobial Agents

Considering pteridine as a worthy structure for improving probes of magnificent therapeutic potentials, some new pteridine conjugates were synthesized by aminomethylation of benzopteridinethione with a variety of primary aromatic amines and formaldehyde solution (37%) through the Mannich reaction. The proposed mechanism of formation of the synthesized compounds was discussed, and the structure of the newly synthesized compounds was elucidated on the basis of their IR, ¹H NMR, ¹³C NMR, mass spectral, and elemental analyses. Furthermore, some selected compounds were evaluated in vitro for their antimicrobial activities; the preliminary data stated that the majority of the tested compounds exhibited significant antimicrobial activity. Analogues 22 , 23 , 20 , 19 , 24 , and 15 were found to be the most potent against all the tested microorganisms.