Expanded scope in ethylene-alkyne cross-metathesis: coordinating heteroatom functionality at the propargylic position

The Grubbs 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene-substituted ruthenium complex 1 catalyzed ethylene-alkyne cross-metathesis and was shown to tolerate free hydroxyl groups and coordinating functionality at the propargylic and homopropargylic positions. Hindered and enantiomerically enriched 1-substituted alkynes also react efficiently under the reported conditions.     

Benzindoles. 23. 2-formyl- and 3-formyl-4,5-benzindoles

It is shown that, in addition to the usually formed 3-formyl-4,5-benzindole, 2-formyl-4,5-benzindole can be obtained via the Vilsmeier reaction. The IR, PMR, and UV spectra of the 2- and 3-formyl isomers are compared, and their possible conformations are discussed.See [1] for Communication 22.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 343–345, March, 1984.     

Preparation,and infrared and thermal properties of six adducts of tetrakis-(8-hydroxyquinolinato)thorium(IV)

Six adducts of the tctrakis(8-hydroxyquinolinato) complex of thorium(IV) with 8-hydroxyquinoline, pyridine, urea, dimethylsulphoxide, dimethylformamide and 1,10-phenanthroline were prepared and characterized, the infrared bands for the room-temperature forms are given and their particular thermal properties are reported. The thermal analyses were performed mostly in the presence of air, but in some cases an argon atmosphere was used for comparison. The adducts were lost from the principal complex at temperatures varying between 110 and 290°. Intermediate oxygenated complexes were formed in each case at about 400°. The thermal data suggest the standardization of a procedure for the formation of Th(C₉H₆NO)₄.

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Zusammenfassung Sechs Addukte des Tetrakis(8-hydroxyquinolinato)-Komplexes von Thorium(IV) mit 8-Hydroxyquinolin, Pyridin, Harnstoff, Dimethylsulphoxid, Dimethylformamid und 1,10-Phenanthrolin wurden dargestellt und charakterisiert. Infrarotbanden und spezielle thermische Eigenschaften der Raumtemperatur-Formen sind angegeben. Die thermischen Analysen wurden meist in Luft ausgeführt, in einigen Fällen zu Vergleichszwecken aber auch in Argonatmosphäre. Die Addukte wurden vom Komplex bei Temperaturen zwischen 110 und 290 °C abgegeben. Intermediäre oxydierte Komplexe wurden in jedem Fall bei etwa 400 °C gebildet. Die thermischen Daten ermöglichen die Standardisierung eines Verfahrens zur Darstellung von Th(C₉H₆NO)₄.

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-(8- ) (IV) 8- , , , - , 1,10-. - , . , , . 110–290°. 400° . Th(C₉H₆NO)₄.

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We are grateful to the Bangladesh University Grants Commission for a Fellowship Grant to AR.     

The use of sample additives in flame emission spectrometry

New kinds of sample additives were investigated to increase the efficiencies of desolvation and atomization in flame spectrometry. Hydrazine and nigrosin were chosen as chemical and dye additives, respectively; an enhancement in the flame-emission signal was obtained in both cases. With nigrosin, it was possible to eliminate completely the interference of phosphate on a calcium emission signal. The increase in the signal for both additives was believed initially to be due to the more rapid evaporation of droplets in the sample aerosol. Further evidence, however, suggested that enhanced vaporization is responsible for the observed signal increase. It is suggested that similar sample additives might be useful also in inductively-coupled plasma emission spectrometry.     

Analysis of Azithromycin in Human Plasma by LC–MS–MS

A simple sensitive and selective liquid chromatographic–tandem mass spectrometric method was developed and validated for the quantification of azithromycin in human plasma. Roxithromycin was used as the internal standard. The chromatographic separation was performed on a SunFire C18, 50 mm × 2.1, 3.5 μm column at 30 °C with mobile phase consisted of 1.54 g ammonium acetate, 250 mL water, 570 mL acetonitrile, 180 mL methanol and 0.6 mL glacial acetic acid. Flow rate was 0.2 mL min⁻¹. The work-up procedure involved a liquid–liquid extraction of the compounds. Mass spectrometric data were acquired in single ion monitoring. MRM mode of the ions 749.58 > 591.6 and 837.64 > 158.2 for azithromycin and roxithromycin, respectively. The method was validated in the concentration range of 2–1,000 ng mL⁻¹. Absolute recovery of azithromycin was 81.97%. Retention time for azithromycin was 0.9 and 1.1 min for roxithromycin. The run time was 2 min. This method was found suitable to analyse human plasma samples for application in pharmacokinetic, pharmacodynamic, bioavailability/bioequivalance studies.

     

A study of solar erythema radiation doses

Abstract —Using semi-empirical analytic formulas for the transmitted and scattered ultraviolet spectral irradiance at the ground (Green, A. E. S., T. Sawada and E. P. Shettle, Photochem. Photobiol. 19 , 251–259, 1974), we calculate erythema dose rates and daily erythema doses. Results are illustrated graphically, and for the purpose of photobiological applications are given in terms of approximate analytic forms, with parameters presented in tabular form. The relative erythema data assembled by W. W. Coblentz and R. Stair (U.S. Bureau of Standards J. Res. 12 , 13–14, 1934), as fit by an analytic form, is taken as a standard spectrum in our calculations. Other forms of erythema spectra are also compared.     

Phosphorylthioacetamides in the synthesis of annulated quinoxalines

Diethoxyphosphorylthioacetamide in the reaction with 2,3-dichloroquinoxaline acted as a thionating reagent, giving diethoxyphosphorylacetonitrile and 2-chloro-3-[(3-chloro-2-quinoxalinyl)thio]quinoxaline. Reactions of phosphorylthioacetamides with N-methylquinoxalinium iodide in alcohol media in the presence of a base proceeded stereoselectively to afford cis-3-phosphoryl-1,3,3a,4,9,9a-hexahydro-2H-pyrrolo[2,3-b]quinoxaline-2-thiones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1010–1013, May, 2007.     

Determination of trace inpurities high-purity aluminum oxide by inductively-coupled plasma atomic emission-spectrometry

Trace impurities (Ca, Cu, Fe, Mg, Mn, Na and Si) in 99.99% aluminum oxide were determined by inductively-coupled plasma atomic emission spectrometry (i.c.p./a.e.s.). The sample was fused with lithium carbonate/boric acid to determine Ca, Cu, Mg, Mn, Na and Si or dissolved in phosphoric/sulphuric acids to determine iron. Matrix effects on the calibration graphs for each element were studied: for accurate determinations, calibration solutions must contain lithium and boric acid (or aluminium and phosphoric and sulphuric acids for iron).     

Plasma polymerization. V. A systematic investigation of the inductively coupled RF plasma polymerization of the isomeric tetrafluorobenzenes

A systematic investigation has been made of the composition, gross structural features, and rates of deposition of plasma polymer films produced from the excitation of inductively coupled RF plasmas in the isomeric tetrafluorobenzenes. ESCA data reveal that the dominant reaction involves rearrangement such that under a wide variety of experimental conditions the composition of the crosslinked products remains essentially the same as that of the starting material. Small differences in rates of deposition are observed for the different isomers, and theoretical SCF MO studies at the MNDO level provides a basis for discussion of the experimental data.     

Solvent composition effects in column and thin layer chromatography of aromatic nitro compounds on alumina

Summary The relationship between R _M and the concentration of the polar solvent in the moving phase was investigated for a number of aromatic nitro compounds with additional polar groups (amino, methoxy, carbomethoxy, aldehyde). TLC data were correlated with analogous column chromatography results. Linear R _M (logk') vs. logX _S relationships obtained for both techniques are interpreted in terms of a molecular model of adsorption.