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.     

Studies on the conversions of diols and cyclic ethers—49: Stereochemistry of cyclodehydration of 1,4-diols on the action of brönsted and lewis acids: a comprehensive study

The stereochemistry of the cyclodehydration of (±)- and meso-2,5-hexanediol on the action of various dehydrating agents was investigated. The earlier assumed and confirmed intramolecular S_N2 mechanism for acid-catalysed ring-closure was found to hold in most cases. Various extents of racemisation can be observed on the action of certain Lewis acids, and the solvents concentrated H₂SO₄ and HMPT (hexamethyl phosporic acid triamide) under previously unexamined reaction conditions.     

Relationships for determining the rate constant of the polymerization growth reaction by means of the emulsion polymerization method

Some simple equations for the emulsion polymerization system were derived on the basis of the Smith-Ewart theory. These are used in calculating the molar monomer concentration and rate of polymerization in units of moles per liter per second for the zero-order region with respect to the monomer as well as in calculating the rate constant of the growth reaction.     

Microdynamics of solid anilinium chloride

Intraionic C₃ reorientation of the anilinium NH⁺₃ group was evidenced by measurements of the temperature dependence of the proton spin—lattice relaxation time, by rotating frame experiments and cw NMR data. Analysis of the results yielded a rotor hindering potential E = 33.6 kJ/mole and τ_o = 4 × 10⁻¹³ s.     

Freie Elektronenpaare in lokalisierten CNDO/2-Wellenfunktionen der Stickstoffverbindungen

The method for constructing hybrid orbitals described earlier is now used for the analysis of CNDO/2 wave functions of molecules containing nitrogen atoms in order to get information on the type of hybridization of nitrogen lone pair orbitals in various compounds.     

Mechanism of hydrogenolysis and isomerization of oxacyloalkanes on metals, V. Selectivities of metal catalysts in ring-opening reactions of oxiranes

The deoxygenation of methyloxirane to propene and its isomerization to oxo compounds on a Ni/SiO₂ catalyst were studied in a pulse microreactor, in the presence of H₂ as carrier gas, at 473 K. It was found that the deoxigenation leads to the creation of new types of active centers (Lewis acid site-basic site), which cause a change in the direction of ring opening. The differences in regioselectivity observed between Ni and Cu, and Pt and Pd, can be explained by the different affinities of the metals for oxygen. This finding can be generalized to other oxygen-containing compounds.

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=qa Ni/SiO₂ 473 . , - - , . Ni Cu, Pt Pd . .

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Part IV: J. Catal. (to be published)     

Temperature effects in the oxidation of aliphatic ketones by solutions of thallic sulfate

The oxidation of aliphatic ketones by thallium(III) sulfate in aqueous medium has been studied from the point of view of the temperature effect and the enthalpy-entropy relationship. It has been found that the isokinetic relationship is fulfilled in this case.

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(III) - . , .

     

Analytische Aspekte der Oxydation organischer Stickstoffverbindungen mit Chromsäure. II

Zusammenfassung Eine Halbmikromethode zur Bestimmung der an Kohlenstoff oder Sauerstoff gebundenen Nitro- und Nitrosogruppen in organischen Verbindungen wurde ausgearbeitet. Die Methode beruht auf dem oxydativen Aufschluß der Substanz mit einem Chromsäure—Schwefelsäure-Gemisch, wobei die Nitro- und Nitrosogruppen quantitativ in Salpetersäure übergehen. Diese wird mit Devarda-Legierung in alkalischem Medium zu Ammoniak reduziert, das dann im Stickstoffstrom abdestilliert und acidimetrisch titriert wird.

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Summary A semimicro method for determining nitro- and nitroso groups attached to carbon or oxygen in organic compounds has been worked out. The method is based on the oxidative decomposition of the sample with a chromic acid-sulfuric acid mixture, the nitro and the nitroso groups being quantitatively transformed into nitric acid. The latter is reduced to ammonia by means of Devarda alloy in alkaline medium, and is then distilled off in a stream of nitrogen and titrated with a standard acid solution.

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Résumé On a mis au point une méthode à l'échelle semimicro pour le dosage dans les substances organiques de groupes nitro et nitroso liés au carbone ou à l'oxygène. La méthode repose sur l'attaque oxydante de la substance par un mélange acide chromique-acide sulfurique, ce qui transforme quantitativement les groupes nitro et nitroso en acide nitrique. Au moyen de l'alliage de Devarda en milieu alcalin, on réduit celui-ci en ammoniac que l'on chasse par distillation dans un courant d'azote et que l'on titre par acidimétrie.

     

Glycoprotein synthesis as a function of epithelial cell arrangement: biosynthesis and release of glycoproteins by human breast and prostate cells in organ culture.

We demonstrate that a technique is available to investigate glycoprotein synthesis in organ cultures of human breast and prostate surgical specimens where the 3-dimensional epithelial cell arrangement remains intact. Malignant breast and prostate epithelium maintained their capacity to synthesize glycoproteins for at least 3 days as followed by the incorporation of [3H]glucosamine into macromolecules. Over 70% of incorporation was by malignant cells as judged by autoradiography. Labeled glycoproteins were released into glandular lumina and consequently into the culture fluid. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed predominantly one group of macrmolecules released with an apparent molecular weight of 48,000 +/- 6,000 daltons. This glycoprotein was found in all of the breast specimens studied, which included 1 medullary, 1 infiltrating lobular, and 8 infiltrating duct carcinomas. The pattern was independent of the availability of estrogen receptors. A similar glycoprotein was also observed in the culture media from a Grade I and a Grade II well-differentiated infiltrating prostate carcinoma. Incorporation was below the level of detection in 4 of 6 cases of benign prostatic hyperplasia. A more complex pattern of labeled glycoproteins was found in the media of a Grade II and a Grade III poorly-differentiated prostate carcinoma. The established human mammary carcinoma cell line MCF-7 synthesized and released a similar 48,000 molecular weight glycoprotein but additional components with larger molecular weights were also released. An intriguing interpretation that 3-dimensional tissue integrity restricts some glycoprotein synthesis is discussed. Cells grown in 2-dimensional monolayers could escape from such a topographic restriction and express additional families of glycoproteins.