Highly polarized enamines.

The spatial structure of various derivatives of ,-diamino--cyano--nitroethylene has been investigated using¹H and¹³C NMR spectroscopy. It was shown that the configuration of the investigated push—pull enamines is determined by the possibility of creating an intramolecular hydrogen bond between NH and NO₂ groups or by steric interactions. A series of 3,5-diamino-5-nitropyrazole derivatives has been synthesized by reacting these amines with hydrazine hydrate.For Part 2, see [1].These compounds may also be considered as derivatives of acrylonitrile.Center for Drug Chemistry, All-Russian Chemical and Pharmaceutical Research Institute (TSKhLS-VNIKhFl), Moscow 119815. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 89–98, January, 1997.     

Highly fluorinated heterocycles. Part XII. Some reactions of the heptafluoro-p-dioxanyl anion.

2$\text{H}$-heptafluoro-$\text{p}$-dioxan has been lithiated using methyl lithium in ether and thence converted to heptafluoro-p-dioxan-2-carboxylic acid (characterised as its anilinium and S-benzylthiouronium salts and methyl ester), 2-(heptafluoro-$\text{p}$-dioxanyl)propan-2-ol [dehydrated to 2-(heptafluoro-$\text{p}$-dioxanyl)propene], heptafluoro-$\text{p}$-dioxanyltrimethylsilane, and heptafluoro-2-iodo-$\text{p}$-dioxan. This last was converted to its Grignard reagent, and to bis(heptafluoro-$\text{p}$-dioxanyl)mercury, and was copper-coupled to trans-1-chloro-2-iodoethylene.Decomposition of heptafluoro-$\text{p}$-dioxanyl-lithium gave hexafluoro-$\text{p}$-dioxene. 2$\text{H}$-heptafluoro-$\text{p}$-dioxan, with KOH and formaldehyde, afforded hexafluoro-$\text{p}$-dioxanylmethanol.     

Highly stable copper/carbon dot nanofluid

Copper/carbon dot nanohybrids (Cu/CD NHs) were prepared via a facile precipitation method through a disproportionation reaction. The surface characterization was performed by various techniques such as XRD, FTIR and TEM. Then, water-based nanofluids composed of Cu/CD NHs at 0.1 and 0.5 mass% were prepared, and their thermo-physical properties including thermal conductivity, viscosity, density and specific heat were evaluated at various temperatures. The water-based Cu/CD nanofluid demonstrated to be a potential heat transfer fluid with a high stability. It was found that the thermal conductivity can be enhanced by increasing the nanoparticle concentration and temperature. Almost 1.25-fold increase in thermal conductivity has been achieved by raising the temperature up to 50 °C and at the concentration of 0.5 mass%. The heat capacity was found to increase with increasing concentration. Moreover, by increasing temperature the density and viscosity of the as-prepared nanofluid decreased, whereas the heat capacity showed an increasing trend.     

Highly enantioselective desymmetrizations of meso-anhydrides

Readily available, low molecular cyclohexane-based organocatalysts promote highly enantioselective desymmetrizations of cyclic meso-anhydrides applying alcohols and benzyl mercaptan as nucleophiles. Both succinic and glutaric anhydrides furnished the corresponding products with up to 96% ee in mostly quantitative yields.     

Highly excited states decay in p-terphenyl crystals. Magnetic field effect investigation

The magnetic field effect on the fluorescence of p-terphenyl crystals was investigated. It is shown that in aromatic crystals an important decay channel of highly excited states is autoionization followed by a triplet exciton creation by collision of the emitted electron.     

Highly Stereoselective Tandem Pummerer Reaction/α-Hydroxy Imine Rearrangement of E.P. β-Sulfinylenamines

Abstract.

The highly stereoselective tandem Pummerer reaction/alpha;-hydroxy imine rearrangement of E.P. α-fluoroalkyl-β-sulfinylenamines affording chiral non-racemic fluoropyruvaldehydes N,S-ketals is described.     

Cover Picture: Highly Stable Molecular Borromean Rings (Chin. J. Chem. 2/2018)

The cover picture shows a series of Cp*Rh‐based molecular Borromean rings (BRs), which consist of three chemically independent rings that are locked in such a way that no two of the three rings are linked with each other. Interestingly, the structure of BRs is very similar to Kong Ming Lock (孔明锁), a kind of Chinese traditional six‐piece burr puzzle. In this work, some of as‐synthesized BRs display high stability in solution. The reason is related to the length ratio of the long‐arm linker and short‐arm linker, where smaller aspect ratios of the metallarectangles promote improved stability of the BRs in solution. Increasing the width of the metallaligand or pyridyl ligand hinders the formation of BRs and leads to unoccupied monomeric rectangles, which were further used as catalysts. More details are discussed in the article by Jin et al. on page 106–111.

     

Highly selective isomerization of N-allylamides and N-allylamines

A highly selective rhodium and ruthenium catalyzed transformation of N-allylamines and N-allylamides to the corresponding 1-propenyl derivatives is described. Strong E-selectivity in the isomerization of allylamines was observed. The first catalytic system containing a transition metal complex for Z-selective isomerization of allylamides is presented. An application of siliceous mesoporous cellular foams for effective removal of the catalyst from the post-reaction mixture is described.     

Highly selective C-H functionalization/halogenation of acetanilide

Highly regioselective C-H functionalization/halogenation of acetanilides to produce ortho-haloacetanilides was catalyzed by Pd(OAc)2 and Cu(OAc) 2 with CuX2 as the halogen source.     

Highly enantioselective hydrogenation of N-phthaloyl enamides

Rh- or Ru-catalyzed highly enantioselective hydrogenation of N-phthaloyl enamides is presented. Electron-rich TangPhos and DuanPhos are found to be effective ligands for Rh-catalyzed hydrogenation of α-aryl enamides and up to 99% ee has been achieved. In contrast, for the hydrogenation of α-alkyl enamide, the Ru-C₃-TunePhos complex is more effective and up to 69% ee can be observed. This work is the first report of the hydrogenation of N-phthaloyl enamides.     

Highly efficient ortho-fluoro-dimeric cinchona-derived phase-transfer catalysts

A series of cinchona alkaloid-derived dimeric quaternary ammonium salts were prepared as chiral phase-transfer catalysts by the introduction of various functional groups on the phenyl ligand. Among them, the 2-F-substituted derivative 21 showed the highest enantioselectivity in the alkylation of the glycine anion equivalent 1 (97 to >99% ee).     

Highly active copper catalysts for steam reforming of methanol. Catalysts derived from Cu/Zn/Al alloys

-Hydrogen transfer from -phenylethyl hydroperoxide (HROOH) to excited anthraquinone, acetophenone and benzophenone occurs only in the polar aprotic acetonitrile. At the same time, the triplet of duroquinone abstracts -hydrogen both in polar and non-polar solvents. The rate constant of the latter reaction decreases with increasing solvent polarity.     

Preparation of Highly Luminescent CdTe/CdS Core/Shell Quantum Dots

A good balance: Oil‐soluble CdTe/CdS core/shell quantum dots (QDs) that emit in the visible and near‐infrared spectral regions with quantum yields up to 92 % (see figure) are prepared by balancing the coordinating capacity and the activation effect of selected surfactants.