Inorganic complexes in volumetric analysis. Part III. Use of ferric fluoride complex in the estimation of iodide

Summary The method for estimation of iodide formulated in the earlier publications of the series bas been modified by the use of sodium fluoride as the complexing agent in the place of oxalate or phosphoric acid. The results obtained are in excellent agreement with the calculated ones and the method has been successfully applied for the estimation of iodide in iodized salt.     

Asymmetric hydrogenation in the presence of bicyclic chiral phosphines

Both enantiomers of trans-2,3-diphenylphosphinomethyl-norbornene-(5), prepared by two independent synthetic routes, were used as ligands in the asymmetric hydrogenation of -acetamidocinnamic acid in the presence of rhodium(I). Small variations in the ligand structure have a remarkable influence on the activity of the catalytic system.

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-2,3----(5), , - (I). .

     

Isolation of ribosomes from cotton seeds

Summary 1. It has been established that the method of precipitation with ethanol in the presence of an increased concentration of Mg²⁺ can be used for the rapid isolation of the ribosome fraction from plant material.2. The optimum conditions for the complete precipitation of the ribosome fraction from a homogenate of cotton seeds have been selected.3. By treating an extract of the seeds with 0.5 M KCl it was possible to reduce the amount of tRNA in a preparation of the total rRNA.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 852–856, November–December, 1977.     

Spot tests for calcium sulphate, lead sulphate, silver, thallium, and formaldehyde based on reactions with selenosulphate

Summary Spot tests have been described for calcium sulphate, lead sulphate, silver, thallium and formaldehyde based on the reaction with selenosulphate. In these reactions either red elemental selenium (CaSO₄, CH₂O) or black metal selenide (PbSO₄ Tl, Ag) is formed. The limits of identification are: 0.2 mg of PbS04 or CaSO₄, 2 g of Ag, 10 g of Tl, 0.2 g of CH₂O.

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Zusammenfassung Für Calciumsulfat, Bleisulfat, Silber, Thallium und Formaldehyd werden Tüpfelproben beschrieben, die auf Umsetzungen mit Selenosulfat beruhen. Hierbei -wird entweder rotes elementares Selen abgeschieden (CaSO₄ CH₂O) oder schwarze Selenide werden gebildet (PbSO₄, Tl, Ag). Die Nachweisgrenzen betragen: 0,2 mg PbSO₄ oder CaSO₄, 2 g Ag, 10 g Tl, 0,2 g CH₂O.

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This paper has been dedicated to Prof. Dr.Fritz Wessely, Vienna, on the occasion of his 70th birthday.     

The potentiometric and amperometric determination of silver with mercaptophenylthiothiadiazolone and mercaptobenzthiazole

Summary The previously described gravimetric determinations of silver were used for the potentiometric and amperometric determinations of silver in the presence of interfering cations. The potentiometric titration of silver with MFTD (MBT) is a simple matter, if enough complexone is present, in both ammoniacal and neutral solutions. The amperometric determination of silver with MFTD (MBT) is carried out in neutral solution, containing complexone, with rotated platinum electrode and mercury-mercuric iodide half-cell, short-circuited through a microammeter. The only interfering elements are mercury, gold, and some of the platinum metals.     

Nouvelle méthode de détermination des taux de réativité des copolymères par résonance magnétique nucléaire: Application aux poly(méthacrylate de méthyle–chlorure de vinylidène)

Constant-composition copolymers of methyl methacrylate and vinylidene chloride produced by radical copolymerization are studied by ¹H-NMR at 60 and 250 MHz. The different methods of the literature for the derivation of reactivity ratios from either the copolymer composition or the sequence average lengths, or even the diad distribution, are applied but lead to rather dispersed results. A new graphical method is proposed, based on the use of peculiar values of the triad distribution functions. It allows us to detect a penultimate effect for the vinylidene chloride-rich region. In the same range, a change in tacticity of the diads and triads on the methylmethacrylate sequences, as compared with homopolymers, is observed; it suggests that the anomaly is caused by the competition of the depropagation reaction.     

A physico-chemical study of iron-chromium-molybdenum catalysts

In the study of the Fe_1–xCr_xMo_1·5O₆ system by X-ray, IR and Mössbauer methods the formation of solid state substitution solutions has been detected, which possess similar catalytic properties in methanol oxidation.

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, , Fe_1–xMo_1·5O₆ , .

     

The theory and practice of polarography in melts

Some of the problems of using solid micro-electrodes in molten salts are discussed. The technique of high-temperature polarography is described and some of the anomalous features of the results are examined.     

Toluene oxidation on LaCoO3, LaFeO3 and LaCrO3 perovskite catalysts. A comparative study

Vapor phase catalytic oxidation of toluene over perovskites viz., LaCoO₃, LaCrO₃ and LaFeO₃ has been studied. The maximum activity was observed at 450°C. The oxidation is first order. The order of catalytic reactivity is LaCoO₃>LaFeO₃>LaCrO₃. The activation energy (E_a) values for LaCoO₃, LaFeO₃ and LaCrO₃ are 13.4, 23.93 and 25.31 kJ/mol, respectively.