Oxidative imination of sulfur-containing heterocycles

For the first time, the sulfur heteroatom of 4-oxothiazolidines has been iminated with sodium salts of chloroamides of arenesulfonic acids and N-chloroamides of carboxylic acids. The effect of the substituents and the size of the ring on the ability of the ring sulfur atom to undergo oxidative imination was studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 609–612, May, 1979.     

How trimethyl(trifluoromethyl)silane reacts with itself in the presence of naked fluoride--a one-pot synthesis of bis([15]crown-5)cesium 1,1,1,3,5,5,5-heptafluoro-2,4-bis(trifluoromethyl)pentenide

Reactions of trimethyl(trifluoromethyl)silane in the presence of "naked" fluoride proceed up to a temperature of +5 degrees C mainly with formation of [Me3Si(CF3)2]-. A further rise of temperature up to about 20 degrees C gives evidence for the formation of a salt with the 1,1,1,2,3,6,6,6-octafluoro-2,4,4,5,5-pentakis(trifluoromethyl)hexan-3-ide anion. This intermediate decomposes at room temperature into the 1,1,1,3,5,5,5-heptafluoro-2,4-bis(trifluoromethyl)pentenide anion. The bis([15]crown-5)cesium salt, [Cs([15]crown-5)2][(CF3)2CCFC(CF3)2] has been characterized unambiguously as the stable final product of this reaction sequence. Thermal decomposition of this salt opens a convenient nontoxic route to obtain 1,1,3,3-tetrakis(trifluoromethyl)allene, (F3C)2C=C=C(CF3)2.     

New Hybrid Material Based on Multiwalled Carbon Nanotubes Decorated by Rhenium-Tungsten Nanodendrites

Re–W nanoparticles are deposited onto multiwalled carbon nanotubes by the metal organic chemical vapor deposition technique. A mixture of dirhenium decacarbonyl and tungsten hexacarbonyl is used as a precursor. Nanoparticles of hybrid materials are studied by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray phase analysis. It is found that in a wide range of ratios of the precursors (dirhenium decacarbonyl and tungsten hexacarbonyl), the crystalline component is a Re–W phase, and the morphology of the nanoparticles is the same as that of the nanodendrites.     

Reaction of o-phenylenediamine with acetoacetic and α-chloroacetoacetic esters

The reactivities of acetoacetic and -chloroacetoacetic esters in the reaction with o-phenylenediamine are compared. In contrast to the available data, it was established that in polyphosphoric aicd (PPA) acetoacetic ester is converted to 4-methyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one and ethyl 3-(2-aminoanilino)-crotonate, while chloroacetoacetic ester is converted to 2-methylbenzimidazole. At 20 °C chloroacetoacetic ester is converted to ethyl 2-chloro-3-(2-aminoanilino)crotonate. The conversion of this ester to 2-methyl-3-ethoxy-2,3-dihydro-1H-1,5-benzodiazepin-2-one was studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1255–1259, September, 1981.     

The observation of sonic range velocities of normal zone propagation in high current density superconductor

The sonic range velocities of normal zone propagation in high current density superconductor were observed. The experimental results were obtained on samples of 0.16–0.11 mm thickness of a monofilamentary NbTi wire with critical current density J_c about 10⁶ A/cm². The s→n change of the sample sections was recorded after the normal zone stimulation by the magnetic field impulse. The voltage increasing speed reached 1.5×10⁷ V/s, and the normal zone propagation velocity exceeded 5±1 km/s. This high velocity can be caused by the detonation-like propagation of normal phase in superconductor with high current density.     

The signature of the Ricci curvature of left-invariant Riemannian metrics on four-dimensional lie groups. The unimodular case

We obtain a complete classification of all the possible values of the signature of the Ricci curvature of left-invariant Riemannian metrics on four-dimensional unimodular Lie groups.     

Synchrotron,X-Ray,and Electron Microscopic Studies of Catalyst Systems Based on Multiwalled Carbon Nanotubes Modified by Copper Nanoparticles

Physics of the Solid State - The results of the studies of a composite based on multiwalled carbon nanotubes (MWCNTs), onto the outer surface of which nanosized copper particles are deposited by...     

Silver compounds in synthetic chemistry : Part 5: Selective syntheses of trifluoromethylketones, RCOCF3, from trifluoromethylsilver, AgCF3, and corresponding acyl chlorides, RCOCl

Trifluoromethylketones of aromatics, heteroaromatics and olefins are formed selectively from reactions of trifluoromethylsilver and the corresponding carboxylic acid chlorides in moderate to excellent yields. The conditions chosen are dependent on the nature of the acyl chloride. Attempts to prepare alkyl(trifluoromethyl)ketones yielded product mixtures of the corresponding acyl fluorides, trifluoromethyl-, pentafluoroethyl- and n-heptafluoropropyl ketones.     

S-Trifluoromethyl esters of thiocarboxylic acids, RC(O)SCF3

S-Trifluoromethyl esters of different types of thiocarboxylic acids have been prepared in moderate to excellent yields from halide substitution reactions of the corresponding acid chlorides and tetramethylammonium trifluoromethylthiolate. C₆F₅C(O)SCF₃ undergoes a surprising rearrangement on attempted isolation to give 4-CF₃SC₆F₄C(O)F, which was converted into the corresponding acid.