Synthesis of positively charged lipids containing a 1,3-oxathiolane cycle

Positively charged lipids of the 1,3-oxathiolane series were synthesized by interaction of 2-pentadecyl-5-tosyloxymethyl- or -5-iodomethyl-1,3-oxathiolane with 2-(N,N-dimcthyl-amino)ethanol.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2347–2349, September, 1996.     

Biamperometric neutralisation titrations in non-aqueous solvents applying tin electrode pair for the end-point detection

Summary Tertiary amines and salts of organic acids in acetic anhydride with 5% of acetic acid were titrated applying a biamperometric indicating system consisting of a polarised or unpolarised pair of tin electrodes by means of 0.1 N perchloric acid in glacial acetic acid. Amounts of 15.4–29.8 mg were analysed with average deviations of <0.6%, the results obtained being in a good agreement with those of potentiometry. The biamperometric end-point detection using an indicating system of polarised pair of tin electrodes can be applied for coulometric determinations of these bases with satisfying accuracy. By means of anodic generation of hydrogen ions in the presence of hydroquinone amounts of 0.5–1.0 mg were titrated with average deviations of < 1.3%. The results obtained were compared with those obtained of catalytic thermometric and photometric titrations.

---

Biamperometrische Neutralisationstitrationen in nichtwärigen Lösungsmitteln unter Anwendung eines Zinn-Elektrodenpaares als Indicatorsystem

Zusammenfassung Tertiäre Amine und Salze organischer Säuren werden in Acetanhydrid mit 5% Essigsäure durch Titration mit einer 0,1 N Lösung von Perchlorsäure in Essigsäure bestimmt. Das verwendete biamperometrische Indicatorsystem besteht aus einem Paar polarisierter oder nichtpolarisierter Zinnelektroden. Mengen von 15,4–29,8 mg wurden mit einer mittleren Abweichung von <0,6% analysiert. Die Ergebnisse stimmen gut mit denen von potentiometrischen Titrationen überein. Die biamperometrische Endpunkttechnik mit polarisierten Zinnelektroden kann für coulometrische Bestimmungen dieser Basen mit zufriedenstellender Genauigkeit benutzt werden. Durch anodische Erzeugung von Wasserstoffionen in Gegenwart von Hydrochinon wurden Mengen von 0,5–1,0 mg mit einer mittleren Abweichung von < 1,3% titriert. Die Ergebnisse wurden mit denen von katalytisch-thermometrischen und photometrischen Titrationen verglichen.

     

Reagents for new heteroannelation reactions III. 2-(Methylthio)-2-thiazoline

Summary A variety of partly novel tri- and tetracyclic hetero systems were obtained by reaction of heteroaromatic 2-aminoesters with 2-(methylthio)-2-thiazoline, yielding double-annelation of a thiazolo[2,3-b]pyrimido moiety in a one-pot process.On leave from University of Chittagong, Bangladesh     

19F and 1H NMR spectra of halocarbons

19F NMR chemical shifts and coupling constants are reported for 215 compounds. For 77 of these compounds, 1H NMR spectral data are also given. Long-range couplings, including 8J(F,F) and 5J(F,H), are reported. The complexity of halocarbon spectra owing to the presence of rotational isomers, asymmetric centers, long-range couplings, and chlorine isotope effects are illustrated, and the methods used for analyzing such complex spectra are briefly discussed.     

Zwei neue Metatitanate mit fünffach koordiniertem Titan: CsNaTiO3 und RbNaTiO3

Two New Metatitanates with Five-coordinated Titanium: CsNaTiO₃ and RbNaTiO₃ [1] The new oxides CsNaTiO₃ (I) and RbNaTiO₃ (II) are obtained by heating well grounded mixtures of the binary oxides in Ni-tubes as colourless platelike crystals. I: CsO_0.56, NaO_0.48 and TiO₂, Cs:Na:Ti = 1.1:1.1:1.0; 600°C, 61 d as well as CsO_0.97, NaO_0.48 and Ti₂O₃, Cs:Na:Ti = 1.5:3.0:1.0; 760°C, 27 d. II: RbO_0.52, NaO_0.48 and TiO₂, Rb:Na:Ti = 1.1:1.1:1.0; 750°C, 14 d as well as RbO_0.98, NaO_0.48 and Ti₂O₃, Rb:Na:Ti = 1.5:3.1:1.0; 760°C, 27 d. CsNaTiO₃ (orthorhombic, Cmcm) is nearly isostructural with KNaTiO₃ [2]; a = 601.4(1) pm, b = 1 120.3(1) pm, c = 563.4(1) pm (Guinier-Simon-Data, Z = 4). RbNaTiO₃ (monoclinic, C2/c) is isostructural with KNaTiO₃; a = 590.3(1) pm, b = 1 098.4(1) pm, c = 555.1(0) pm, β = 92.15° (Guinier-Simon-Data, Z = 4). Both structures are determined by using four-circle diffractometer data (CsNaTiO₃: Siemens AED2, 2 896I_o(hkl), MoKα , R = 2.4%, R_w = 2.3%; RbNaTiO₃: Philips PW 1 100, 2 743I_o(hkl), AgKα , R = 9.9%, R_w = 8.9%; additional data see text). The Madelung Part of Lattice Energy (MAPLE), Effective Coordination Numbers (ECoN), Mean Fictive Ionic Radii (MEFIR) and the Charge Distribution in Solids are calculated and discussed.     

对甲基苯乙炔基铁硫配合物(μ-p-CH_3C_6H_4C≡CS)(μ-RS)Fe_2(CO)_6的合成、结构及构象

通过对甲基苯乙炔基溴化镁断裂μ-S_2Fe_2(CO)_6的S—S键可得“开式”中间体(μ-p-CH_3C_6H_4C≡CS)(μ-BrMgS)Fe_2(CO)_6。该中间体与有机卤化物作用生成了11种通式为(μ-p-CH_3C_6H_4C≡CS)(μ-RS)Fe_2(CO)_6的“开式”铁硫原子簇配合物。还确定了某些配合物可能的构象体及其含量比。     

On the loss of cadmium, antimony and silver during dry ashing of biological material

Summary The loss of cadmium, antimony and silver during dry ashing of marine weeds, mussels and shrimps was studied with the aid of radioactive tracers. Except for antimony all biological material was labelled by uptake of the radioactive tracers by the organisms while still alive. At an ashing temperature of 500° C and below no significant loss by volatilization of these elements occurs. The results obtained at higher temperatures with cadmium show that the behaviour of this element may depend on the composition of the organic material. Retention on the wall of quartz crucibles did not cause serious losses.

---

Über den Verlust an Cadmium, Antimon und Silber bei der Trockenveraschung von biologischem Material

Zusammenfassung Mit Hilfe radioaktiver Tracer wurden die Verluste an Cadmium, Antimon und Silber bei der Trockenveraschung von Seetang, Muscheln und Krabben untersucht. Mit Ausnahme von Antimon wurden alle Materialien mit den Tracern durch Aufnahme im lebenden Zustand markiert. Bei Veraschungstemperaturen von 500° C und darunter konnten keine signifikanten Verluste durch Verflüchtigung der Elemente festgestellt werden. Das Verhalten von Cadmium bei höheren Temperaturen kann von der Zusammensetzung des organischen Materials abhängen. Verluste durch Haften an der Wand des Quarztiegels waren unbedeutend.

     

Phenolic Compounds of Plants of the Scutellaria L. Genus. Distribution, Structure, and Properties

Information on flavones, flavanones, flavanonols, flavonols, chalcones, isoflavones, biflavonoids, lignoflavonoids, and lignane glycosides and stilbenes isolated from plants of the Scutellaria L. genus was systematized and reviewed. A list of 208 phenolic compounds was given according to flavonoid type with an indication of the plant sources, structures, and physicochemical properties and citations of the original articles.     

Shape of the proton potential in an intramolecular hydrogen-bonded system. Part II

The crystals of 5,5′-dibromo-3-diethylaminomethyl-2,2′-biphenol N-oxide were studied by X-ray and FT-IR spectroscopy. Within this molecule two short OHO intramolecular hydrogen bonds are formed. The NO?H⁺?O⁻ bond between the OH and the N-oxide groups is very strong, of 2.419(7) Å between the oxygen atoms. The proton potential of this hydrogen bond is flat, broad and has probably no barrier—consequently it could not be located from X-ray diffraction data. The other hydrogen bond formed between two hydroxyl groups appears asymmetrical from FT-IR spectra, and shows also relatively limited proton polarizability. The molecular conformation is non-planar, due to strong overcrowding effect between the oxygen atoms involved in the hydrogen bonds.     

Macrocycle opening in formyl derivatives of benzocrown ethers under the action of methylamine

A new method for synthesizing nitrogen-containing podands by nucleophilic regioselective cleavage of the macrocycle in formyl derivatives of benzocrown ethers by heating with methylamine and methylammonium chloride has been developed. This reaction is the first example of crown ether opening by a nitrogen-containing nucleophile.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 950–953, May, 1995.