Peculiarities of foam glass synthesis from natural silica-containing raw materials

Journal of Thermal Analysis and Calorimetry - The primary source of the power for marine industry comes from large two-stroke low-speed marine diesel engines. The more severe emission regulations...     

Deprotonation of 1,1′-methylenebis[4-tert-butyl-2-(diphenylphosphino)-benzene] and its analogues: synthesis and crystal structure of {5-But-2-[4-But-2-(Ph2P)C6H3(Ph)CH]C6H3P(Ph)K(OEt2)}2

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Synthesis of novel 1,2-dihydropyrrolo[1,2-a]pyrazin-1(2H)-one derivatives

The iodolactonization product obtained from methyl 7-allylpyrrolo[2,3-d]pyrimidine-6-carboxylate was used for the synthesis of novel 1,2-dihydropyrrolo[1,2-a]pyrazin-1(2H)-one derivatives, containing carboxamide- and methylamine-groups on the pyrrole ring of the heterocycle.     

Astolides A and B,antifungal and cytotoxic naphthoquinone-derived polyol macrolactones from Streptomyces hygroscopicus

Two new natural compounds, astolides A,B, were isolated from Streptomyces hygroscopicus collected from the alkaline soil obtained from Saratov region, Russia. The structures were elucidated by interpretation of UV spectroscopic, MS, 1D and 2D NMR data. The relative configurations were determined by analysis of NOESY/ROESY spectra and coupling constants. The isolated compounds were evaluated for their inhibitory activity against bacteria, fungi and yeasts and showed pronounced antifungal activity. Both compounds are noticeably cytotoxic, being active against doxorubicin-resistant human leukemia cell line.     

Dissociation Constant of Acetic Acid in (N,N-Dimethylformamide + Water) Mixtures at the Temperature 298.15 K

In the present work the thermodynamic dissociation constants of acetic acid were determined in (N,N-dimethylformamide (DMF) + water) mixtures over the DMF mole fraction range from 0 to 0.65 at the temperature 298.15 K by the potentiometric titration method. The dissociation constant in pure DMF was obtained by extrapolation and comparative calculation methods. The dependence of the acetic acid dissociation constant on the mixed solvent composition was fitted with linear multiple regression of the solvatochromic parameters of (DMF + water) mixtures at every studied composition.     

Synthesis and structure of half-sandwich SmII and YIII cyclopentadienyl halide complexes with the penta(benzyl)cyclopentadienyl ligand

Russian Chemical Bulletin - The exchange reactions of equimolar amounts of potassium penta(benzyl)cyclopentadienide CpBn5K (CpBn5 = C5(CH2Ph)5) and SmI2(THF)2 or YCl3 afforded the corresponding...     

Large magnetic anisotropy of chromium(III) ions in a bis(ethylenedithio)tetrathiafulvalenium salt of chromium bis(dicarbollide), (ET)<Subscript>2</Subscript>[3,3′-Cr(1,2-C<Subscript>2</Subscript>B<Subscript>9</Subscript>H<Subscript>11</Subscript>)<Subscript>2</Subscript>]

The synthesis of a radical-cation salt based on a derivative of tetrathiafulvalene, (ET)₂[3,3′-Cr(1,2-C₂B₉H₁₁)₂] (ET?=?bis(ethylenedithio)tetrathiafulvalenium), was accomplished by electrochemical anodic oxidation of ET in the presence of (Me₄N)[3,3´-Cr(1,2-C₂B₉H₁₁)₂] in the galvanostatic regime. An electric conductivity σ (293 K)?=?7 × 10^?3 Ohm^?1 cm^?1 with semiconductor activation energy E_a???0.1 eV in the range of 127–300 K was observed. The crystal structure of (ET)₂[3,3′-Cr(1,2-C₂B₉H₁₁)₂] was determined by X-ray diffraction at 173 K, revealing the presence of structural tetramers in radical-cation stacks. The magnetic properties of the complex were investigated in the temperature range 1.8–300 K using magnetometry and EPR, showing that the magnetic structure of (ET)₂[3,3′-Cr(1,2-C₂B₉H₁₁)₂] consists of two independent magnetic subsystems. Cation radicals form a rectangular magnetic lattice in the ab-plane with significant antiferromagnetic exchange interactions. The chromium bis(dicarbollide) anions are characterized by unusually strong positive zero-field splitting of the Cr(III) ions, which was confirmed by ab initio calculations.     

Selenoacetalyzation of 4‐Formylpyrazoles in the Presence of Trimethylchlorosilane

The reaction of 3,5‐dimethyl‐4‐formylpyrazoles, bearing various substituents at N‐1 atom, with propane‐1,3‐diselenol and 2‐hydroxypropane‐1,3‐diselenol in the presence of ТМSCl proceeds without heating to chemoselectively give hitherto unknown 2‐(pyrazol‐4‐yl)‐1,3‐diselenane hydrochlorides in high yields. The latter are easily transformed to the corresponding free bases—2‐(pyrazol‐4‐yl)‐1,3‐diselenanes. The ¹⁵N chemical shifts of the pyrazole ring in 2‐(pyrazol‐4‐yl)‐1,3‐diselenanes obtained by 2D HMBC‐gp (¹⁵N‐¹H) technique are indicative of the N‐2 atom protonation in hydrochlorides.