Planar Chromatography of Some 1-Arylpiperazines Behaving as Dopaminergic Ligands

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of fourteen 1-arylpiperazine derivatives has been studied by thin-layer chromatography on both silica...     

Some covering properties in topological and uniform spaces

Recent progress in selection principles theory is discussed and is illustrated mainly by the Hurewicz covering property and its strong version, the Gerlits-Nagy property GN(*). Some results that have not been published elsewhere are given with proofs.     

Viskosimetrische Untersuchung des Systems LiNO3−H2O

Zusammenfassung Die Temperaturabhängigkeit der Viskosität im System LiNO₃–H₂O und im Temperaturbereich 20–70°C wird in der Gleichung =A expB/T=T ₀ zusammengefaßt; aus der so erhaltenen Beziehung werden Rückschlüsse auf die Struktur der Lösungen gezogen.

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Temperature dependence of the viscosity in the system LiNO₃–H₂O is expressed by =A expB/T-T ₀ in the temperature range 20–70°C. Possible relations to structural changes in the solutions are considered.

     

Correlation between Lipophilicity of the Ligands and the Hepatobiliary Properties of the Radiopharmaceuticals: Approach to the Development of New IDA Derivatives

The partition coefficient (log P) for n-octanol/water system was calculated applying PACO program for various theoretically possible mono and dihalogenated IDA derivatives. Some of the synthesized ligands (SOLCOIODIDA, IODIDA and DIIODIDA) were labeled with the technetium-99m. The biodistribution and influence of bilirubin on their biokinetics were investigated in rats. The correlation between partition coefficients of ligands increase (log P) and better hepatobiliary properties of ^99mTc-IDA derivatives was determined. The values of log P increase from 1.16 for SOLCOIODIDA, 3.11 for IODIDA to 3.47 for DIIODIDA. In correlation with these results, biliary excretion decreased for 59% for ^99mTc-SOLCOIODIDA and 11% for ^99mTc-IODIDA and ^99mTc-DIIODIDA under hyperbilirubinemia (3.5 min after injection) and 45%, 11% and 0.38% respectively (15 min after injection). The highest biliary excretion had ^99mTc-DIIODIDA (55.4% for 3.5 min). Considering the correlation between hepatobiliary properties and log P, the evaluation of biological properties for various trifluoromethyl mono and dihalogenated IDA derivatives was performed on the basis of the calculated log P in order to synthetize a new radiopharmaceutical for hepatobiliary scintigraphy.     

Stereochemistry of cyclic ether formation—II : Intramolecular cyclisation of secondary aliphatic alcohols to tetrahydrofuran-type ethers

The mechanism and stereochemistry of δ-C atom functionalisation in the reactions of secondary straight-chain aliphatic alcohols with lead tetraacetate, ceric ammonium nitrate, and heavy metal (Pb⁴⁺, Hg²⁺, Ag⁺) salts (AcO)^?1, O^2?, CO₃^2?-halogen (I₂, Br₂, Cl₂) combinations are discussed. By demonstrating the intermediacy of 5-bromo-2-hexanol, it was confirmed that the dark silver oxidebromine induced cyclisation of 2-hexanol (and alcohols in general) involves (as the other hypohalite reactions) intramolecular 1,5-hydrogen abstraction by alkoxy radicals and formation of δ-bromohydrins. A novel and simple procedure for obtaining tetrahydrofurans from alcohols by way of the hypochlorite reaction, using silver or mercuric salts and chlorine, is described.     

Investigation of changes in catalyst for conversion by means of steam during use in an industrial reactor

A study was made of the changes in the active component of a commercial catalyst for methane reforming by means of steam, as a function of its duration of use and of its position in an industrial reactor. The samples for examination were taken after 3, 8, 9 and 20 months of catalyst use, and from seven different levels in the reformer tube, ranging from the top to the bottom.DTA, TG, IR spectroscopy, X-ray diffraction and surface area determination were used to follow the catalyst changes.

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Zusammenfassung Veränderungen der aktiven Komponente eines kommerziellen Katalysators zur Methanreformierung mittels Wasserdampf wurden in Abhängigkeit von der Betriebsdauer und der Lage im industriellen Reaktor untersucht. Proben für die Untersuchung wurden nach 3-, 8-, 9- und 20-monatiger Betriebsdauer aus 7 verschiedenen Höhen vom Boden bis zum Kopf des Reformer-Rohres entnommen. Veränderungen des Katalysators wurden mittels DTA, TG, IR-Spektroskopie, Röntgendiffraktometrie und Oberflächenmessungen verfolgt.

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Validation of liquid chromatographic method for analysis of lidocaine hydrochloride, dexamethasone acetate, calcium dobesilate, buthylhydroxyanisol and degradation product hydroquinone in suppositories and ointment

In this paper, there was developed a sensitive, precise and accurate reversed-phase liquid chromatographic (RP-HPLC) method and validated for simultaneous determination of lidocaine hydrochloride, dexamethasone acetate (DA) and calcium dobesilate (CD) in suppositories and ointment. Also there was achieved a parallel analysis of buthylhydroxyanisol, as a preservative, and hydroquinone, as a degradation product of calcium dobesilate, present in these dosage forms. The relative standard deviation (RSD) values for all five compounds indicated a good precision and accuracy of the RP-HPLC method. Method is selective, sensitive and reproducible with good recovery values and can be applied in simultaneous determination of all mentioned compounds.     

Investigation of isothermal bulk polymerization ofo-alkyaryl methacrylates by DSC

The kinetics of the AIBN-initiated free radical bulk polymerization of fiveo-alkylphenyl methacrylates was studied by means of DSC in the temperature range 353–373 K, and the enthalpy of polymerization, the overall reaction rate constant and the activation energy were determined. The results were compared with those published recently on correspondingp-alkylaryl methacrylates. All measured reaction rate constants were found to increase with increasing temperature and to decrease with increasingo-alkyl substituent mass and size. It was shown thato-substituents influence the rates of polymerization to a greater extent thanp-substituents. At about 373 K, all differences in rate, most probably resulting from steric hindrance caused by the alkyl groups, disappear in both series, a phenomenon earlier observed for dimethyl phenyl methacrylates.This work was supported by the Ministry of Science of the Republic of Serbia.