Showing papers on "Nickel boride published in 2008"

Swift and Selective Reduction of Nitroaromatics to Aromatic Amines with Ni–Boride–Silica Catalysts System at Low Temperature

Abstract: Various nitroaromatics are successfully reduced to amines with 100% conversion and selectivity in methanol at low temperature (≈5 °C), by using versatile system of 5% Ni–SiO2 catalyst and NaBH4 and in situ generation of Ni boride. The catalytic efficiency of Ni loading (5%, 10% and 15%) with silica or titania as support materials is investigated for reduction of nitrobenzene. The Ni–titania/NaBH4 system recorded lower conversion and selectivity. The IR studies indicate that silica support does not have free –OH group on its surface. Thus the nickel boride is anchored to the silica to facilitate the catalytic process.

Facile reductive dehalogenation of organic halides with nickel boride at ambient temperature

Abstract: The hydrodehalogenation of a series of aryl, alkyl, allyl, and benzyl chlorides, bromides, and iodides has been carried out efficiently using nickel boride in methanol at ambient temperature, leadi...

A novel synthesis of 2-substituted 2H-imidazo[1,5-b]isoquinoline-1,5-diones by in situ desulfurization

Abstract: A novel synthesis of 2-substituted 2H-imidazo[1,5-b]isoquinoline-1,5-diones by reductive desulfurization of a variety of 2-substituted 3-thioxo-2H-imidazo[1,5-b]isoquinoline-1,5-diones is reported with nickel boride in dry methanol at ambient temperature.

Refinement of the crystal structures of scandium nickel boride, Sc2Ni21B6 and zirconium nickel boride, Zr2Ni21B6

Abstract: B6Ni21Sc2, cubic, Fm3m (no. 225), a = 10.5940(3) Å, V = 1189.0 Å, Z = 4, Rgt(F) = 0.018, wRref(F) = 0.041, T = 293 K. B6Ni21Zr2, cubic, Fm3m (no. 225), a = 10.6223(4) Å, V = 1198.6 Å, Z = 4, Rgt(F) = 0.018, wRref(F) = 0.039, T = 293 K. Source of material Samples with stoichiometric compositions were synthesized by arc-melting of mixtures of elements: Zr foil (99.99 %, Alfa, Johnson Matthey), Sc pieces (99.95 %, Ames), Ni foil (99.99 %, Alfa Aesar), and crystalline B powder (99.995 %, Chempur). The obtained reguli were sealed in Ta containers and annealed in evacuated silica tubes at 950 °C for 14 days. Needle-like single crystals were separated from well-crystallized ingots by mechanical fragmentation. The magnetization of polycrystalline sample pieces was measured in a SQUID magnetometer (MPMS XL-7, Quantum Design) in external fields between 20 Oe and 70 kOe and temperatures of 1.8 400 K. Experimental details Refinement of lattice parameters for each compound was performed on 30 reflections by least-squares fitting of powder diffraction data (HUBER G670 Imaging Plate Guinier Camera, CuK21 radiation, ) = 1.54056 Å) with LaB6 as internal standard (a = 4.1569 Å).

Effects of Lead and Boride Inhibitors on the Passivity of Nickel Alloy 600 Surface

Abstract: Corrosion-resistant nickel-based Alloy 600 is susceptible to a lead-induced stress corrosion cracking (PbSCC) in aqueous solutions. The lead species incorporated into the oxide at the alloy surface degraded the passivity, and caused the PbSCC. Effects of lead on the properties of the surface passive films were investigated. The cross sections of the surface films were examined by the transmission electron microscopy and the species present in the films were analyzed with the energy dispersive x-ray spectroscopy and the x-ray photoelectron spectroscopy. In-depth concentration profiles of the species were analyzed by using an ion sputtering technique. The electrochemical impedance spectroscopy technique was used to characterize the electrochemical behaviors. Effectiveness of a nickel boride inhibitor was evaluated. The boride inhibitor altered the properties of the passive film, and significantly reduced the susceptibility to the PbSCC.

7,11-Diaryl-2,4-diazaspiro[5.5]undecane-1,5,9-triones: A New Series of Spiroheterocycles.

Abstract: A novel two step synthesis of 7,11 -diaryl-2,4-diazaspiro[5.5]undecane-1,5,9-triones has been reported based on double Michael addition of 2-thiobarbiturates or N,N'-diaryl-2-thiobarbiturates with dibenzalacetones followed by reductive desulfurization with nickel boride.

Microwave‐Assisted Synthesis of 4‐Quinolylhydrazines Followed by Nickel Boride Reduction: A Convenient Approach to 4‐aminoquinolines and Derivatives.

Abstract: Nickel(II) chloride/sodium borohydride combination was employed for the reduction of 4-hydrazinoquinoline derivatives to the corresponding anilines. This reductive protocol was efficiently applied for the reductive cleavage of monosubstituted hydrazines. We described herein the microwave-assisted synthesis of 4-hydrazinoquinolines, which furnished a high yielding and rapid two-step procedure for the synthesis, under mild conditions, of 4-aminoquinolines as antimalarial precursors.

Performance of NiB inhibitor for PbSCC of alloy 600 in Pb-contaminated water and caustic solutions

Abstract: Nickel-based iron-chromium alloys are used as steam generator (SG) tubing materials in nuclear power plants (NPPs) but experience intergranular stress corrosion cracking (IGSCC) and lead stress corrosion cracking (PbSCC) due to the harsh operating conditions of NPPs. In order to improve the integrity of SGs, many studies have sought suitable inhibitors for IGSCC, while those for PbSCC have been sought to a limited extent. In this study, the performance of nickel boride (NiB) as an inhibitor for PbSCC was evaluated. Nickel boride has been shown to be a good inhibitor for IGSCC of Alloy (or Inconel) 600 in a caustic aqueous solution containing no lead (Pb). No significant SCC was observed to occur in Alloy 600 tested in pure water under the slow strain rate test (SSRT) condition in this study. A mixed mode of IGSCC and TGSCC, however, occurred relatively easily in Alloy 600 tested in pure water containing lead oxide (PbO) at 315 °C. The susceptibility of Alloy 600 to SCC decreased with the addition of NiB, implying that NiB can be used as an inhibitor for PbSCC in Pb-contaminated water.